whole cement process

about us: cement manufacturer & suppliers in india - wonder cement ltd

Wonder Cement is a cutting-edge cement manufacturing company with an ambition to establish itself as a leading player in the industry. Enriched with the heritage of R.K. Marble, a leading name in the marble industry, our corporate culture is built on the values of quality, trust and transparency. An emphasis on technological superiority enables us to differentiate our offering through impeccable quality and effective communication. With an extensive network of dealers & retailers, we own a position in the premium segment of the market.

The state of the art manufacturing unit was established in technical collaboration with ThyssenKrupp and Pfeiffer Ltd. of Germany, the world leaders in cement technology, to produce cement at par with international standards. Special effort was taken to ensure that the plant upholds the latest environmental norms and with the help of a reverse air bag house, ESP, and a number of nuisance bag filters, the plant remains clean & dust free.

Together with the grinding units in Dhule (Maharashtra), Bhadnawar (Madhya Pradesh), and the recently commissioned grinding unit in Jhajjar (Haryana), our total installed capacity now stands at 13MTPA. We are also planning to further expand our manufacturing capacity with the introduction of a fourth line at the Nimbahera Integrated Manufacturing Unit.

Wonder Cement came into being with a dream to build a better place for the youth, their families and the nation at large. Not only did we dream of being one of India's top cement manufacturer, but transformed this dream into a reality by setting up one of the first fully-automated plants in India. We have invested in state-of-the-art German technology and were one of the first to introduce new standards of quality control.

Cement is the foundation upon which we construct our lives, our homes, our schools, our roads and our societies. Our structures will not only serve the generations of tomorrow, but will also carry our legacy as they stand the test of time.

We have come a long way and have always strived to blur the thin line between dreams and realities. Today, Wonder cement's parent company, R K Marble, is a thriving brand in India. Since dreams and possibilities arise with every new beginning, Wonder Cement's promise to you is Ek Perfect Shuruaat.

I would like to extend my gratitude to all employees, customers, suppliers, financial institutions, advisors and other stakeholders, for their dedication and undying support. Our central focus is and will always be to create value for our stakeholders. As long as we are committed to providing best quality of product and services, I am sure we will continue to be India's most respected cement producing company.

The journey of Mr. Ashok Patni, chairman emeritus of R.K. Group, is a narration of deep values, ambition and success. From his native place in Kishangarh, with the legacy of a family-run wholesale business in grains, his quest began with a dream for a larger canvas.

Mr. Patni set up R.K. Marble in May 1989 with a clear vision and objective to establish the nascent company as a major player in the national and international market. Today, the company employs the latest mining technology, has expanded production abroad and holds the title of the largest marble producer from the Guinness Book of World Records.

Currently he serves a pivotal role in the diversified business of cement, where he has imprinted his trademark of honesty, integrity, transparency and quality. Under his leadership, Wonder Cement has already acquired the distinction of being the best quality cement in the country, certified and buttressed by numerous independent agencies, dealers and end-users.

For Mr. Patni, work is a passion - a hobby practiced and pursued from his early calls at the factory. He has a profound love for nature and is highly passionate about development of greenery and plantation. His strong commitment to society has been the driving force behind the extensive welfare and social programs undertaken by the company, which go above and beyond the mandatory corporate social responsibility.

His determination, his leadership and his compassion are qualities that make Mr. Ashok Patni a true visionary. In the years to come, his influence will be of paramount importance to the success of the company as he continues to build the dream that began his career.

Always keen on adding value to his family business, Mr. Vimal Patni took charge to diversify into production of cement. He gave a resounding start to his maiden venture by creating a brand associated with the company's philosophy of quality, trust and transparency. Mr. Patni, now in his late 40's, exudes full confidence about the company's future based on the pace of growth in expanding its capacities. Shortly after winning a government bid for the mining of limestone in Nimbahera, Mr. Patni began a consulting process with some of the foremost and acknowledged leaders in the cement industry, also consulting Ernst & Young before finalizing the factory blueprint. He worked overtime from the foundation of the factory until the point of production, resulting into creation of the huge infrastructure spread over 1050 hectare (mines and factory) in an industry record for any greenfield plant. A go-getter, he learned the nuances of the cement trade in a very short span and is now at the helm of every activity.

The creation of additional jobs for the youths had always been his motto and the present endeavor is geared to fulfilling that objective. Mr. Patni has sought to imbibe the best corporate practices at the factory - promoting a clean and green environment and fostering a work culture comparable to the best in the industry. While he cherishes traveling and exploring various countries, he finds greater peace and satisfaction by giving back to our own society through thoughtful philanthropic activities.

Always keen on adding value to his family business, Mr. Vimal Patni took charge to diversify into production of cement. He gave a resounding start to his maiden venture by creating a brand associated with the company's philosophy of quality, trust and transparency. Mr. Patni, now in his late 40's, exudes full confidence about the company's future based on the pace of growth in expanding its capacities. Shortly after winning a government bid for the mining of limestone in Nimbahera, Mr. Patni began a consulting process with some of the foremost and acknowledged leaders in the cement industry, also consulting Ernst & Young before finalizing the factory blueprint. He worked overtime from the foundation of the factory until the point of production, resulting into creation of the huge infrastructure spread over 1050 hectare (mines and factory) in an industry record for any greenfield plant. A go-getter, he learned the nuances of the cement trade in a very short span and is now at the helm of every activity.

The creation of additional jobs for the youths had always been his motto and the present endeavor is geared to fulfilling that objective. Mr. Patni has sought to imbibe the best corporate practices at the factory - promoting a clean and green environment and fostering a work culture comparable to the best in the industry. While he cherishes traveling and exploring various countries, he finds greater peace and satisfaction by giving back to our own society through thoughtful philanthropic activities.

After successfully completing his graduation in Economics & Management from the Cardiff University, UK, he joined the accounting firm, Price Waterhouse Cooper, where he learnt and built for himself a foundation of good corporate governance. Mr. Vikas Patni always had an inclination of joining the family business and taking it forward to new heights. When he did, he brought about a directional change by shifting R.K. Marble's policy of only processing marble from it's own mines to importing of marble, thus becoming one of the largest suppliers of imported marble in India. He was instrumental in creating a footprint for the company in Turkey by acquiring mines and establishing R.K. Marble on firm footing in international markets.

He firmly believes in honesty and hard work, an integral part of the continued success of the R.K. Group. He foresees Wonder Cement as a leading cement company based on the growth momentum it has achieved in a brief span of three years. His international exposure combined with his ethics of corporate governance will provide fresh insight on attaining the highest standards in the cement business. He is an avid traveller and loves exploring exotic locations in particular, whenever he finds time from work.

Octogenarian, Mr. Ali, has set up 21 large projects during his chequered career spanning nearly six decades. He exudes a passion to build projects and share his knowledge with others. He has been associated with formulating, planning, implementation and commissioning of projects with Hindustan Zinc Limited and Binani Industries Limited. He is a fatherly figure in the cement industry as persons who worked under him as supervisors are today CEOs of large conglomerates supplying capital goods and services to the cement industry.

What had started with a simple official visit by senior members of Wonder Cement to his residence in 2009 for enlisting his support for the company has now cemented into strong ties between him and the promoters in pushing Wonder Cement on a high growth trajectory. His presence on the board gave Wonder Cement immediate trust amongst suppliers and vendors in gaining the best of the terms of supply. Mr. Ibrahim Ali has an abiding interest in creating a futuristic cement plant for the company that integrates best available technology of the world with the company's overriding concern for good corporate governance.

Mr. Ali has a deep religious bent of mind that has taken him on pilgrimages to places of worships of all faiths and religion. A globetrotter as well, Mr. Ali has travelled to different destinations from highly urban centres to the lap of pristine nature.

Octogenarian, Mr. Ali, has set up 21 large projects during his chequered career spanning nearly six decades. He exudes a passion to build projects and share his knowledge with others. He has been associated with formulating, planning, implementation and commissioning of projects with Hindustan Zinc Limited and Binani Industries Limited. He is a fatherly figure in the cement industry as persons who worked under him as supervisors are today CEOs of large conglomerates supplying capital goods and services to the cement industry.

What had started with a simple official visit by senior members of Wonder Cement to his residence in 2009 for enlisting his support for the company has now cemented into strong ties between him and the promoters in pushing Wonder Cement on a high growth trajectory. His presence on the board gave Wonder Cement immediate trust amongst suppliers and vendors in gaining the best of the terms of supply. Mr. Ibrahim Ali has an abiding interest in creating a futuristic cement plant for the company that integrates best available technology of the world with the company's overriding concern for good corporate governance.

Mr. Ali has a deep religious bent of mind that has taken him on pilgrimages to places of worships of all faiths and religion. A globetrotter as well, Mr. Ali has travelled to different destinations from highly urban centres to the lap of pristine nature.

Mr. Kiran Patil possesses over three decades of diversified experience in the cement industry. His expertise and leadership roles are not only limited to India but also the Philippines and Vietnam. An acclaimed industry stalwart, Mr. Patil has played a pivotal role in manufacturing functions including operations, maintenance, and projects. He is a Mechanical Engineer and holds a degree in MBA (Finance). He jumpstarted his career in the cement industry and has worked with many prestigious organizations. Today, with a clear perspective of the cement business, Mr. Patil has powerful control over cost optimizing plant assets. Over the last few decades, he has developed an extensive network with stakeholders and is most renowned for his Technology-Driven approach and Project Management skills.

Apart from his work, Mr. Patil is an avid reader and enjoys traveling to places with abundant greenery and natural resources. His people-centric approach and eye for detail ensuring the safety and well-being of his team is what sets him apart in his management style and makes him a distinctive leader.

Mr. Vivek Patni inherits the glorious business legacy from his renowned family members belonging to the house of Patnis. He is the eldest son of Mr. Vimal Patni and his ambitions for the company are no less illustrious than his father's. After completing his schooling in Udaipur, he traveled to the UK for higher studies. Upon returning to India, he earned a further degree in commerce in preparation for his upcoming plunge in the highly competitive cement industry.

Now in his early 20s, Vivek evinces keen interest in all the corporate affairs of the company and plays a pivotal part in all the key policy making decisions. A keen observer with an analytical mind, he spearheads the branding, communications, and marketing, which he has identified as a thrust area for the company. He received the Shaan e Rajasthan by Zee Media and the Emerging Leader award at World Today Business Conclave IUA-The New Superpower by URS Asia One, at Abu Dhabi for his outstanding contribution in taking the company to new heights.

He is an avid sports enthusiast with a special inclination for cricket and always stands at the forefront in Wonder Cement's sports building initiatives. His passion and dedication will prove as guiding forces in achieving his aspiration to make Wonder Cement into a leading global brand.

Mr. Vivek Patni inherits the glorious business legacy from his renowned family members belonging to the house of Patnis. He is the eldest son of Mr. Vimal Patni and his ambitions for the company are no less illustrious than his father's. After completing his schooling in Udaipur, he traveled to the UK for higher studies. Upon returning to India, he earned a further degree in commerce in preparation for his upcoming plunge in the highly competitive cement industry.

Now in his early 20s, Vivek evinces keen interest in all the corporate affairs of the company and plays a pivotal part in all the key policy making decisions. A keen observer with an analytical mind, he spearheads the branding, communications, and marketing, which he has identified as a thrust area for the company. He received the Shaan e Rajasthan by Zee Media and the Emerging Leader award at World Today Business Conclave IUA-The New Superpower by URS Asia One, at Abu Dhabi for his outstanding contribution in taking the company to new heights.

He is an avid sports enthusiast with a special inclination for cricket and always stands at the forefront in Wonder Cement's sports building initiatives. His passion and dedication will prove as guiding forces in achieving his aspiration to make Wonder Cement into a leading global brand.

Widely reputed for innovative solutions and breakthrough results across his career, Mr. Sanjay Joshi has, for over two decades, proved himself to be an inspiring leader in every organisation hes been a part of. A Chemical Technologist from UDCT, Mr. Joshi is also an alumnus of IIM-Calcutta.

A firm believer in leading by example, Mr. Joshi has consistently driven initiatives that have raised the bar of efficacy & accountability, beating the odds against rising costs. In his previous associations be it at Everest Industries Ltd, where he was business head or at Asian Paints, where he functioned as a senior marketing leader over 12 years; he single-handedly drove the fastest growing and most profitable business segments. He specially enjoys creating structure and alignment in new and unexplored areas.

Mr. Parmanand Patidar has been deeply involved with the R. K. Group since its early days in 1991, having been instrumental in expanding the production of marbles as well as in the establishment of the cement business. His more than 20 years of association with the group comes from his passion for building the necessary structure needed for running general administration and creating a team that can deliver.

In R K Marble, he had pioneered mining operations hand in hand with Patni Brothers, whether it be in Morwad or Majoli or Banswara. He was also vested with the responsibility of liaisoning with different stakeholders - a task which he had performed with great finesse and accuracy. Smooth running of the administration being the essence of his working style, he insists always in solving problems, even intricate ones.

Mr. Patidar exhibits a unique blend of desire and drive in completing a project. Now in his early fifties, has the satisfaction of seeing Wonder Cement having achieved a growth faster than it was expected. His expertise lies in matters related to leasing, land acquisition, solving legal matters and even local disputes. He is the trouble shooter of the Group.

Mr. Patidar is a man in a hurry, always imbued with a spirit of work, done perfectly and handed over to the team. He then earnestly looks forward to a new project. It gives him immense pleasure and satisfaction in the execution of any new project-its various challenges and crafting a strategy to overcome them. For him work never stops but whenever he can take out time, he likes to use it to spend most it with his family and explore new places around the world.

Mr. Parmanand Patidar has been deeply involved with the R. K. Group since its early days in 1991, having been instrumental in expanding the production of marbles as well as in the establishment of the cement business. His more than 20 years of association with the group comes from his passion for building the necessary structure needed for running general administration and creating a team that can deliver.

In R K Marble, he had pioneered mining operations hand in hand with Patni Brothers, whether it be in Morwad or Majoli or Banswara. He was also vested with the responsibility of liaisoning with different stakeholders - a task which he had performed with great finesse and accuracy. Smooth running of the administration being the essence of his working style, he insists always in solving problems, even intricate ones.

Mr. Patidar exhibits a unique blend of desire and drive in completing a project. Now in his early fifties, has the satisfaction of seeing Wonder Cement having achieved a growth faster than it was expected. His expertise lies in matters related to leasing, land acquisition, solving legal matters and even local disputes. He is the trouble shooter of the Group.

Mr. Patidar is a man in a hurry, always imbued with a spirit of work, done perfectly and handed over to the team. He then earnestly looks forward to a new project. It gives him immense pleasure and satisfaction in the execution of any new project-its various challenges and crafting a strategy to overcome them. For him work never stops but whenever he can take out time, he likes to use it to spend most it with his family and explore new places around the world.

Mr. Joshi carries with him the comprehensive strength of his three decade experience as a technical head across the cement industry in India, leading the way in that domain with companies like JK Cement, Aditya Birla Group (Cement Division) and Vikram Cement.

Mr. Joshi has been associated with Wonder Cement since its inception, overseeing the overall functions of the plant - planning, monitoring, coordinating and organizing unit operations. Evidence of his technical capabilities is evident in the record time in which he set up Wonder Cement's Line-one greenfield plant. He now handles the dual responsibility of looking after Line-one as well as the expansion of Line-two. Mr. Joshi has been a strategist since schooldays, which is also reflected in his passion for playing chess. At Wonder Cement, he visualizes a three-fold increase in the plant capacity by various technical enhancements to attain a majority market share in key markets.

Well respected in the cement industry, Mr. Wadhwas association with the industry dates back to the early 80's when the sector was in its nascent stages. He continues to be a leader in the industry with his role as the President & Business Head (North) at Wonder Cement. He has served as Sr. Vice-President Marketing at Shree Cement and also in a similar capacity at Binani Cement . He has also been associated with JK Lakshmi Cement as Advisor (Marketing). Driven by a passion for building a team of professionals, equipped to face the challenges posed by competitive peers in the industry , building and nurturing a brand has always been a challenge taken head-on by him through a focused mind and perception.

Today, he strategizes the company's sales and distribution strategy and positioning in the fast growing North India market. With his hold and goodwill in the industry, along with his strong rapport with the dealers, his role is to embark and strengthen Wonder Cements footprint in the North India market.

Well respected in the cement industry, Mr. Wadhwas association with the industry dates back to the early 80's when the sector was in its nascent stages. He continues to be a leader in the industry with his role as the President & Business Head (North) at Wonder Cement. He has served as Sr. Vice-President Marketing at Shree Cement and also in a similar capacity at Binani Cement . He has also been associated with JK Lakshmi Cement as Advisor (Marketing). Driven by a passion for building a team of professionals, equipped to face the challenges posed by competitive peers in the industry , building and nurturing a brand has always been a challenge taken head-on by him through a focused mind and perception.

Today, he strategizes the company's sales and distribution strategy and positioning in the fast growing North India market. With his hold and goodwill in the industry, along with his strong rapport with the dealers, his role is to embark and strengthen Wonder Cements footprint in the North India market.

Being one of the youngest CA in the country at the time, Mr Sailesh Mohta had to wait 6 months to get his CA Membership. That did not stop him from scaling to the heights he has reached today. With over 30 years of experience in the cement industry, his experience is not only immensely valuable but also insightful. Not only does he come with a strong academic background, extensive management experience but he also strongly believes in team work.

Prior to this, Mr. Mohta was the Head of Marketing of a leading cement brand, and had a fruitful stint. He's persistent, believes in bringing out the best in others and is extremely sharp and focused.

He's also a family man. His family comprises of his wife, and two children. In his leisure time he enjoys maintaining an active lifestyle and enjoys hitting the gym, swimming and other activities. He believes in living a balanced life, and truly brings a level of sportsmanship to his work, that defines his entrepreneurial skills.

Mr. Ravindra Singh Mohnot is a leading practicing Chartered Accountant with expertise in almost all the sectors of financial and management services. Associated with R.K. Group since its inception in 1989, in 2010, R.K. Group approached Mr. Mohnot with the challenge of venturing into the cement industry - a completely unknown and unchartered territory for the Patni brothers. Being a part of their think tank played an important role in the successful installation of the plant in a record time and the unique successful branding in a short span. Today, the Nimbahera Greenfield cement plant has a capacity of 6.75 million tons per annum and its growth in such a short span of time is testament to Mr. Mohnot's vision and guidance.

Mr. Mohnot is also the partner of R Mohnot & Co., the sole firm in Rajasthan that specializes in operations such as establishing new ventures, raising finances, advising on financial structure and tendering legal advice. His personal expertise includes joint venture agreements, shareholder agreements, feasibility studies and market surveys.

Mr. Mohnot, now in his late fifties, incorporated R K Marble in 1989, arranged the funding needs for its various business activities from banks and financial institutions. His vision of corporatizing marble industry as a whole and R K Marble in particular bore fruition when the company earned a place in Guinness book of world records as the highest producing marble industry in the world.

Mr. Ravindra Singh Mohnot is a leading practicing Chartered Accountant with expertise in almost all the sectors of financial and management services. Associated with R.K. Group since its inception in 1989, in 2010, R.K. Group approached Mr. Mohnot with the challenge of venturing into the cement industry - a completely unknown and unchartered territory for the Patni brothers. Being a part of their think tank played an important role in the successful installation of the plant in a record time and the unique successful branding in a short span. Today, the Nimbahera Greenfield cement plant has a capacity of 6.75 million tons per annum and its growth in such a short span of time is testament to Mr. Mohnot's vision and guidance.

Mr. Mohnot is also the partner of R Mohnot & Co., the sole firm in Rajasthan that specializes in operations such as establishing new ventures, raising finances, advising on financial structure and tendering legal advice. His personal expertise includes joint venture agreements, shareholder agreements, feasibility studies and market surveys.

Mr. Mohnot, now in his late fifties, incorporated R K Marble in 1989, arranged the funding needs for its various business activities from banks and financial institutions. His vision of corporatizing marble industry as a whole and R K Marble in particular bore fruition when the company earned a place in Guinness book of world records as the highest producing marble industry in the world.

Mr. Tarun Chauhan is a man of many talents, having lead a career spanning from cricketer to advertising professional. At the young age of 18, Tarun Singh Chauhan showed remarkable self assurance on the cricketing field, but he was someone with a marked difference - trading the bat and ball for a career in advertising.

After associating with some of the world's best agencies, he was nominated as President of Lowe after being with the company for nearly 10 years. However, Chauhan thought the job was getting too comfortable and less challenging, so from a senior manager in JWT in the late 1990's, he returned to JWT as Managing Partner. Recently, with the launch of TSC Consulting, he aims to build a reservoir of the best management talent that will help companies, brands and Governments win.

As an advisor to Wonder Cement, his main focus is on making Wonder Cement the most preferred brand in the cement category. He is meticulously involved in the process of building the brand Wonder Cement and wants to leave no stone unturned to achieve his vision of making Wonder Cement one of the most respected brands in the country.

For a man who has worn many hats and is always pressed for time, he still religiously and regularly makes way for following his hobbies and doing what the heart wants. He is fond of growing his own food, spending time at his country home harvesting paddy, running a dairy, breeding goats, and working with and riding on his pet horses.

RK Marble is the worlds largest marble producing company which has built a legacy of unmatched quality since 1989, and is today recognised across the globe as a leading processor/producer of exquisite marble.

Through the use of state-of-the-art cutting edge technology, we consistently bring the largest volumes of the finest marble to the world. Catering to the needs of each and every individual, we deliver a wide spectrum of products, backed by a plethora of services at price points accessible by every buyer.

Wonder Home Finance Ltd. is a NHB-registered housing finance company based out of Rajasthan. It was incorporated with a view to provide finance through home loans and business MSME loans, keeping in mind the Pradhan Mantri Awas Yojana (PMAY) to provide finance to lower and middle-class segment of the society in semi-urban and rural areas.

At Wonder Home Finance, we aim to deliver the highest quality products & services to our customers through proven professionals, best-in-class technology and customer friendly processes. We act transparently, ensuring that our customers have all the information they need for each decision they make and we aim to celebrate this important journey with our customers by hand holding them every step of the way, while keeping things absolutely simple.

Please be advised that we do not take direct online orders for our products and services and never compel consumers to pay in advance via UPI or any other electronic payment mode, whether through net banking or otherwise on any web link. Only authorized dealers are allowed to offer our products. Customers can contact our local dealers/authorised retailers or authorized sales representatives for more information and purchases. For further assistance please contact our toll-free number 1800313131.

cement industry - an overview | sciencedirect topics

The cement industry is the most important consumer of rubber waste. It uses 236,000 t of scrap tires (26 MJ/kg calorific heat) and 290,000 t of industrial waste (plastic waste, paper, textiles, etc., 22 MJ/kg caloric heat) (VDZ, 1999). Table VI.5.21 shows a comparison of components of traditional fuels and scrap tires.

In 1999, scrap tires supplied about 6% of the total fuels required (VDZ, 1999). They are fed in whole to the primary entering point of rotary kilns. If sufficient air is provided, complete combustion is achieved without increasing emissions. Sulfur dioxide is absorbed in clinker.

The cost of treatment amounts to about 100/t rubber waste. For imported coal, the cost is about 80/t. Therefore, the cement industry charges about 80130/t scrap tire to compensate for the difference (Bilhard, 1997).

The cement industry is one of the main industries necessary for sustainable development. It can be considered the backbone for development. The main pollution source generated from cement industry is the solid waste called cement by-pass dust, which is collected from the bottom of the dust filter. It represents a major pollution problem in Egypt where around 2.4 million tons per year of cement dust is diffused into the atmosphere causing air pollution problems because of its size (1-10 microns) and alkalinity (pH 11.5).

Cement by-pass dust is naturally alkaline with a high pH value and represents a major pollution problem. The safe disposal of cement dust costs a lot of money and still pollutes the environment. The chemical analysis for the by-pass dust is shown in Table 13.7.

Because of the high alkalinity of the cement by-pass dust, it can be used in the treatment of the municipal sewage sludge, which is considered another environmental problem in developing countries since it contains parasites such as Ascaris and heavy metals from industrial waste in the city. Although sludge has a very high nutritional value for land reclamation, it might contaminate the land. The safe disposal of sludge costs a lot of money and direct application of sludge for land reclamation has a lot of negative environmental impacts and is very hazardous to health.

Mixing the hazardous waste of cement by-pass dust with the environmentally unsafe sewage sludge will produce a good quality fertilizer. Cement by-pass dust will enhance the fermentation process of the organic waste and kill all microbes and parasites. The high alkalinity cement bypass dust fixes the heavy metals present in the product and converts them into insoluble metal hydroxide. Hence preventing metal release in the leachate. Agricultural wastes must be added to the mix to adjust the carbon to nitrogen ratio as well as the pH value for better composting (El Haggar 2000). The produced fertilizer from composting is safe for land reclamation and free from any parasites or microbes that might exist in raw sludge.

The U.S. cement industry consists of 39 companies that operate 118 cement plants in 38 states. While its production levels have grown since 1985, the industry's energy intensity declined by 35% between 1985 and 2000 (Figure 10).

The cement manufacturing process involves three components: the mining and preparation of inputs; the chemical reactions that produce clinker; and the grinding of clinker with other additives to produce cement. The feed for older kilns is a slurry of inputs, the wet kiln process, while large new plants mix dry materials for introduction to the kiln. Energy use varies with the process and characteristics of the plant, but in general about 90% of the energy use, and all of the fuel use, occurs in the manufacture of clinker in the kiln. The chemical process that converts limestone to lime, produces roughly the same amount of carbon dioxide gas as that generated by the energy used in its production for coal-fired kilns. Technologies that allow production of cement with a lower per-ton share of clinker thus yield multiple benefits.

Upgrading a kiln from wet to dry, and from a long dry kiln to a preheater, precalciner kiln results in major energy efficiency gains but for a price that requires a payback period of at least ten years. Worrell et al. (2004) conclude that these upgrades are attractive only when an old kiln needs to be replaced. More incremental upgrades could yield commercially attractive benefits including advanced control systems, combustion improvements, indirect firing, and optimization of components such as the heat shell. While opportunities vary with specific plants, the combination of these activities appears to yield an improvement in energy use on the order of 10%. Recovering heat from the cooling stage also yields substantial savings. If the heat is used for power generation, it can save up to half of the electricity used in the clinker process. However, taking full advantage of the heat recovery savings may require other major upgrades (National Academies, 2009).

Changing the chemistry of cement to reduce the need for calcination can decrease the high share of clinker that characterizes U.S. production. Options for blended cements include fly ash and steel slag. Fly ash may be particularly promising as it is a coal combustion byproduct that can be reused in many different contexts, such as construction and pavement. Worrell et al. (2004) identify potential energy savings of up to 20% from deployment of blended cement technologies, and larger carbon dioxide emission reductions. Advanced technologies with potential to further improve energy efficiency and emissions include carbon capture and storage technology, fluidized bed kilns, advanced comminution technologies, and the substitution of mineral polymers for clinker (Worrell et al., 2004; Battelle, 2002).

In the cement industry, coal quality is very important as it affects both the quality of the cement and the operation of the plant. The Indian cement industry uses coal because of its abundant availability and shortage of oil and natural gas. Today the Indian cement industry has to use coal of high ash content with varying characteristics. To resolve this problem, the role of coal on cement making and possible improvements in coal quality and consistency have been explored (Kumar, 1994).

The cement industry is the third largest user of coal after the steel and power industries and it consumes more than 5% of total coal produced in India. This coal requirement will go up further with the rapid expansion of the cement industry (for infrastructure projects). Coal is the principal source of fuel for cement kilns. Its consumption per ton of clinker largely depends on the quality and also on how effectively the cement process technology is being used. Coal consumption varies from 0.2 to 0.3 tons for every ton of clinker. It is known that the indigenous cement plants are consuming at least 20%30% more energy than those of similar plants in other countries. Technology obsolescence has been one of the major reasons accounting for the industrys poor performance. The high moisture and ash content of coal make it difficult for the cement units to maintain the quality and quantity of output. Even today, a good part of the installed capacity is linked to the uneconomical wet process. Both the pace of modernisation and the introduction of the latest precalciner technology have to be prioritised and implemented to make this industry competitive.

Coal in the cement industry is used both as a fuel and as a material in the process of cement manufacture. Therefore, both the supply of proper quality of coal and its effective utilisation are a must in the industry. Deteriorating and inconsistent quality of coal supply in terms of high ash and moisture and low HGI can create the following problems according to a study conducted by National Council for Cement and Building Materials (NCB) (Wheelock and Markuszewski, 1984):

It has been observed from different studies on the clinkerraw-coal interrelationship in some Indian cement plants that an ash content of up to 28%30% can be tolerated for burning Indian raw materials, without appreciably affecting kiln operations and clinker quality. However, in the precalciner system, where available, lower-grade coal (up to 40% ash) can be used for partial calcinations.

The present supply of coal to cement plants usually exceeds the desired limit of 27% ash content. It is not possible to maintain the quality of coal as the superior-quality Indian coal has been almost exhausted and a high degree of mechanisation has been adopted, especially in surface mining. Consistent quality can be ensured only through beneficiation.

One of the applications in the cement industry is as raw material for Portland clinker. Portland clinker is manufactured by cindering a homogeneous mixture of ground lime stone and claylike materials. Fly ash can be used as a substitute for these claylike materials because it has practically the same chemical composition.

An other application of fly ash in cement is as raw material for Portland Fly Ash Cement. The cement industry manufactures class A Portland Fly Ash Cement which has the same characteristic properties as normal class A Portland Cement. This is achieved by using a finer ground, high quality Portland clinker and adding approximately 25% high quality fly ash.

In this and the next section, we will describe waste energy potential in the glass and cement industries, both of which are highly energy intensive. Significant amounts of WH are available at such enterprises. The main problem with attempting to capture these waste heat quantities is the lack of consumers of secondary thermal energy resources at the facilities themselves. Therefore, the waste heat can only be effectively utilized for heating purposes by being transferred to the ultimate end users, which can include city district heating systems. However, if that waste heat is converted into electricity at the plant site, then the electricity can be delivered to distant end users via transmission lines.

Some data on worldwide cement production will set the framework for this discussion. Of all the energy expended in the non-metallic mineral sector (9% of total global energy use), manufacture of cement accounts for 7080%. The weighted average among cement-producing countries for specific energy consumption comes to 4.4GJ per tonne of product. China produces nearly one-half of all cement in the world. With so much energy being expended, there is a comparable high potential for energy savings: 2.5 to 3EJ per year may be saved (2833% of all energy consumed in this sector) by various means, including waste energy recovery. Such savings in primary energy would have corresponding reductions in greenhouse gas emissions, particularly CO2 [21].

The process of producing cement and its follow-on product concrete are shown schematically in Fig.9.22 [22]. The raw material, mainly limestone, is crushed in ball mills, passed through an electrostatic precipitator, stored, preheated, and reacted in a high-temperature rotary kiln which yields clinker. To make cement, the clinker must first be cooled. Prior to being crushed in the cement mill, the gypsum produced in the kiln is separated from the main product stream. The output from the cement mill may be blended with other constituents to meet certain specifications depending on the end use. The packaged product is then shipped to the consumers. Electricity is one of the main energy inputs; worldwide, the electricity intensity of cement production is about 91kWh per tonne of cement. An international goal has been established to reduce this to 87kWh/t by 2030 [23].

The main energy consumption (in 109kJ) are for: raw grinding=8.346 (1.88%), kiln heating (fuel combustion)=410.464 (92.68%), and finish milling=24.057 (5.43%) [22]. Although the firing of the kiln consumes the bulk of the energy, there are other places along the production line where waste energy can be recovered. Figure9.23 [24] focuses on the preheater, kiln, and clinker cooler, showing the primary waste heat sources (WHR-I and WHR-II); secondary waste heat may be recovered at the shells of the preheater and the kiln. The primary ones are suitable for power generation while the secondary ones may be appropriate for direct heat applications using hot water [26]. The most commonly used WHR power technologies are steam Rankine cycle with various enhancements and ORC (shown in Fig.9.23), including Kalina, and supercritical CO2 Brayton cycles.

One of the first commercial waste heat power generation plants using ORC technology was implemented by Turboden using the exhaust gas from a cupola furnace in Torbole, Italy [27]. Around the same time, another plant came on-line at Heidelberg Cement in Lengfurt, Germany (1998) by Ormat Technologies.

Figure 9.24 shows the heat balance for a dry ement kiln for the following conditions: exhaust temperature=290390C; cooler exit temperature=250350C. Approximately 35% of the total energy involved can be used for drying the product and for WHR power generation.

Table9.3 provides some information for selected examples of the recovery of waste heat from cement production facilities [21]. The Ait-Baha plant is shown in Fig.9.25 [30]. This plant began with an annual production capacity of 2.2 million tonnes of cement, but currently puts out about 3.6 million tonnes of clinker and 4.9 million tonnes of cement [29].

Mercury is emitted from a variety of anthropogenic and natural sources. Main anthropogenic sources include coal combustion, the cement industry, chlorine manufacturing plants, and waste incineration. Source strengths will vary within each category depending on the mercury content in the raw material and theextent to which control techniques have been employed. Natural sources include volcanoes and diffuse emissions frommercury-containing mineralizations. Different emission sources emit different fractions of mercury species (see Speciation below). The global anthropogenic emissions of mercury have been estimated to be 1900 t, with Asia contributing more than 50% and Europe and North America less than 25% each.

Natural emissions and reemissions are exceedingly difficult to quantify. Emissions from natural surfaces (soils and water) may also originate from previously deposited anthropogenic mercury as well as from natural sources. The variability in time and with geographical location is also considerable. Most estimates suggest that the natural emissions are of the same order of magnitude as the anthropogenic emissions.

Instant chilling process is a physical method, which modifies the properties of steel-making slag for utilization in the cement industry (Montgomery and Wang, 1991, 1992). It is done in four stages. The first is air cooling where the molten slag is placed on shallow plates to a bed thickness of approximately 100 mm and air cooled for 4 minutes. This is followed by an initial water cooling cycle during which the slag bed is continuously water sprayed for about 20 minutes to produce an end temperature of 500 C. After water cooling the slag is loaded into slag carts and transported to a spraying station for further spraying for 4 minutes to reach an end temperature of 200 C. Finally, the slag is placed in a water pool and cooled to around 60 C to complete the process and it is sent for magnetic screening to separate the iron fraction. The slag is treated in a batch process with a total treatment time of 1.5 to 2.5 hours. This is an environmentally friendly process, producing slag of particle size 30-50 m with <4 % free lime content. Magnesium oxide occurs as mixed crystals in the solid solution phase. The composition is not deleterious to the volume stability (Montgomery and Wang, 1991, 1992). Considerable benefits have been reported from the use of instant chilled slag as coarse aggregates in concrete. They include increased strength of the concrete, an increase in the modulus of elasticity, a reduction in the brittleness and an increase in the fracture toughness (Montgomery and Wang, 1991, 1992).

The paper mill and pulp industry produces enormous quantities of paper and pulp products each year. It is the sixth largest polluting industry after the oil, cement, leather, textile, and steel industries, and many environmental contaminants are associated with the discharge of paper and pulp mill sludge (Ali and Sreekrishnan, 2001). About 6094% of organic content is available in paper mill sludge, which has the potential for use as a soil amendment in disturbed lands (Marko and Polonca, 2012). Sludge rich in organic matter is generated in high content in the paper and pulp industries. Although paper and pulp mill sludge is rich in organic matter, it contains less N and P than biosolids and compost (Park etal., 2011). Hence, paper mill sludge often needs additional nutrient input to be used in mine spoil rehabilitation (Park etal., 2011). Paper and pulp mill sludge is managed through its use in landfills and as landfill capping materials, in land spreading, composting, land reclamation, and in employment in brick, light aggregate, and cement production (Marko and Polonca, 2012).

cement making process

Portland cement is the basic ingredient of concrete. Concrete is formed when portland cement creates a paste with water that binds with sand and rock to harden.Cement is manufactured through a closely controlled chemical combination of calcium, silicon, aluminum, iron and other ingredients.

Most of the raw materials, like limestone, clay, iron ores, and coal, should be crushed before their pre-homogenization. Limestone is the primary material in this line, and due to its large particle size and high hardness, its good crushing plays an important role in the whole line. Special stacking and reclaiming technology has been used in the pre-homogenizing process so that raw materials can be better primarily homogenized.

Since the raw meal grinding work takes up more than 30% labor force in the whole dry process cement production line, it is quite important to choose appropriate grinding equipment and technological process so that high-quality products can be obtained.

The preheater is used to preheat as well as decompose raw meal. So the length of the rotary kiln is effectively shortened. And the raw meal can fully exchange heat with the hot gases from the kiln. Because of its rapid and high-efficiency heat transfer, the production efficiency and heat consumption of this production line are greatly improved.

After its preheating and pre-decomposing, the raw meal will be calcined in the rotary kiln, where the generated carbonate will be further decomposed. Meanwhile, a series of solid phase reactions will take place.

About 80% limestone and 20% clay are ground in ball mills with water, producing very fine, thin, paste called slurry. The chemical composition of the slurry is very carefully controlled by adjusting the relative amount of limestone and clay being used.

The slurry slowly moves down the kiln and is dried and heated until it reaches a temperature of almost 1500 degrees Celsius producing "clinker". This temperature completely changes the limestone and clay to produce new minerals which have the property of reacting with water to form a cementations binder. The hot clinker is used to preheat the air for burning the coal, and the cooled clinker is stored ready for use.

The clinker is finely ground with about 5% gypsum in another ball mill, producing cement. (The gypsum regulates the early setting characteristic of cement). The finished cement is stored in silos then carted to our wharf or packing plant facilities.

The mills for grinding the raw materials are 2.4m in diameter and 11.0m long and are driven by 720kw (1000HP) electric motors producing 45t/h of slurry. The cement is ground in two mills: one 2.4m x 11.0m long producing 18t/h of cement; the other 3.8m x 11.4m, powered by 2300kw (3000 HP) electric motor and producing 60 t/h of cement. The kilns are either 98m or 110m long, and produce up to 25 t/h of clinker.

Project Overview Project company: Xinxiang Huaxin Power Group Co., LTD Project address: NO. 184, Baoshan Road, Fengquan District, Xinxiang City Main engine: 3.213 m three-cabin clinker ball mill Production capacity: unknown...

Project Overview Project company: Deng Electric Group Cement Co., Ltd Project address: Zhongyue Street, Dengfeng, Zhenghzou City, Henan Province Contracting mode: general contractingturnkey project Main engine:GRMR53.41 raw material vertical roller...

cement euipment overview | cement making machines | cement plant

How much do you know the cement equipment? Cement equipment refers to the cement making machines that are applied to the cement manufacturing plant. Before learning the cement equipment, we learn the process of cement manufacturing process first.

In general, we can divide the cement production line into three main steps: raw material preparation of cement, clinker production, and finished cement. Each step has some cement manufacturing machines, such as raw mill, cement crusher, cement mill, cement kiln, cement cooler, cement dryer, cement silo, packing machine, etc.

As we all know, the first step of the cement production line is raw material preparation. Cement crusher is the main equipment of this step. The raw materials are fed into cement crusher by vibratory feeder; the breaking material is transported by the belt conveyor to the impact crusher for further crusher.

There are various types of cement crusher on the market, including jaw crusher, cone crusher, hammer crusher, impact crusher, and etc. AGICO Cement can provide all types of cement crusher. Our cement crusher can fully crush the raw material, reduce feed size into the mill, and increase the reaction of raw material in the following cement manufacturing process, reduce the energy consumption of the whole cement production line.

Cement mill is another necessary cement equipment of the cement plant. After raw material crushing, cement mill plays vital role in the further cement manufacturing process. Cement ball mill, vertical cement mill, and cement roller press are common types of cement grinding plant.

Cement mill has two functions of the cement production line. Firstly, cement mill is used to grind the crushed material into fine size before clinker production. A cement mill is also applied for grinding clinker into finished cement. The cement clinker grinding is the last step of the cement manufacturing process, in this step, cement mill grinds cement clinker, gelatinizing agent and other materials into the required size, which can meet the requirement of cement.

AGICO Cement adopts the advanced internal selection and special compartment device, add the activation device. The grinding tail has a special discharge grate plate, which greatly reduces the size of the grinding media of the grinding bin, greatly improves the grinding efficiency, and achieves the goal of high output and low energy.

Cement kiln is used to make cement clinker, and it is the core equipment of cement production line; usually, apply for dry method cement production. There are two main kinds of cement kiln to manufacture cement clinker. One is the cement rotary kiln, and it is horizontal and can rotate. Rotary kiln is widely applied to the cement clinker production. Another one is vertical and fixed kiln, so it is called as a vertical kiln.

AGICO Cement can manufacture cement rotary kiln with advantages of convenient and reliable operation, stable thermal regulation, and high operation rate. Compared to other rotary kilns on the market, our rotary kiln increase operation rate by 10%, production capacity by 5%-10%, widely apply for cement production line of different countries.

Clinker cooler and dryer are two necessary parts of cement clinker production. The dryer produced by AGICO can apply for various raw materials and easy to adjust. During the operation, the dryer supplies heat stably, ensures the drying quality and cement quality. The cement cooler is also used for clinker production. Using blower blowing cold air, quench the cement clinker that laid on the grate plate, decrease the temperature of clinker from 1200 to 100 and below, the cooling exhaust gas enters into the kiln as secondary air.

In fact, every cement plant requires different cement equipment. Except for the cement equipment we mentioned above, there are many other cement making machines applied for the cement plant. In the real application, as a professional EPC cement plant project provider, AGICO Cement always provides a solution according to clients needs, such as mini cement plant, VSK cement plant. We also provide single cement equipment with high quality and competitive price, welcome to contact!

cement manufacturing - components of a cement plant

This page and the linked pages below summarize the cement manufacturing process from the perspective of the individual components of a cement plant - the kiln, the cement mill etc..For information on materials, including reactions in the kiln, see the ' Clinker ' pages. For a more detailed account of the cement production process, see the Understanding Cement book.

Cement is typically made from limestone and clay or shale. These raw materials are extracted from the quarry crushed to a very fine powder and then blended in the correct proportions.This blended raw material is called the 'raw feed' or 'kiln feed' and is heated in a rotary kiln where it reaches a temperature of about 1400 C to 1500 C. In its simplest form, the rotary kiln is a tube up to 200 metres long and perhaps 6 metres in diameter, with a long flame at one end. The raw feed enters the kiln at the cool end and gradually passes down to the hot end, then falls out of the kiln and cools down.The material formed in the kiln is described as 'clinker' and is typically composed of rounded nodules between 1mm and 25mm across.After cooling, the clinker may be stored temporarily in a clinker store, or it may pass directly to the cement mill.The cement mill grinds the clinker to a fine powder. A small amount of gypsum - a form of calcium sulfate - is normally ground up with the clinker. The gypsum controls the setting properties of the cement when water is added.

Articles like this one can provide a lot of useful material. However, reading an article or two is perhaps not the best way to get a clear picture of a complex process like cement production. To get a more complete and integrated understanding of how cement is made, do have a look at the Understanding Cement book or ebook. This easy-to-read and concise book also contains much more detail on concrete chemistry and deleterious processes in concrete compared with the website.

Almost everyone interested in cement is also concerned to at least some degree with concrete strength. This ebook describes ten cement-related characteristics of concrete that can potentially cause strengths to be lower than expected. Get the ebook FREE when you sign up to CEMBYTES, our Understanding Cement Newsletter - just click on the ebook image above.

portland cement manufacturing process in cement plant | agico

The history of cement can be traced back to a mixture of lime and volcanic ash used by the ancient Romans in their building works, while at that time, this technology was not widely used around the world. In 1796, the British used the ancient Roman technology to produce a kind of brown cement from marls, which was named Roman cement because of its similar appearance to the ancient Roman cement and was widely used in buildings because of its good properties. In 1824, Joseph Aspdin, an English man, invented the Portland cement by calcining limestone and clay. Because it had a similar color to the natural stone in island Portland, the cement was named Portland and got a patent. Nowadays, with the improvement of people living standard, our requirements for construction projects are increasing. Portland cement has become the most commonly used construction material in our cities. With the continuous research and improvement of Portland cement, a batch of cement suitable for various special construction projects has gradually appeared in our field of vision. So far, there are more than 100 varieties of cement have been developed around the world.

In the above content, we mentioned that we have developed more than 100 varieties of cement. In addition to the ordinary Portland cement, there are many other types of special cement, such as white cement, colored cement, rapid hardening cement, low heat cement, etc. They are produced by adding different materials in the process of clinker grinding, such as blast furnace slag and fly ash.

White Cement: this kind of cement is also called white Portland cement that famous for its white appearance. It is totally free from oxides of iron, manganese and thorium. The white cement is generally used as decorative materials for various buildings, such as sculpture, floor finishes, etc.

Colored Cement: the colored cement is manufactured by mixing the pigment with the ordinary Portland cement. Its production mainly adopts the staining method and calcination method, the latter of which has a durable color but a high production cost. This cement is widely used in the surface coating of floor, wall and various buildings.

Rapid Hardening Cement: the characteristic of the rapid hardening cement is that it can reach the maximum strength within three days. It is produced by adding more limestone than that of the ordinary Portland cement, and its grinding granularity is also finer so that increasing the speed of the hydration of cement particles. This cement is suitable for emergency repair engineering, low-temperature construction and the production of high-grade concrete precast parts.

Low Heat Cement: low heat Portland cement is a kind of cement containing a large amount of dicalcium silicate and a little tricalcium aluminate. It releases very little heat in the hydration process and has incomparable advantages of high strength in the later solidification period, high durability and corrosion resistance. It is often used in airports, dams and other large concrete structures.

The ordinary Portland cement is also known as silicate cement. At the beginning of the article, we said that Portland cement is so called because the color of concrete made from it is similar to that of natural rocks on the British island of Portland. The raw materials for Portland cement are mainly composed of three components: calcium oxide, silicon dioxide and alumina, which account for 60%, 20% and 10% of the total components respectively. The calcium oxide comes from limestone, while silica and alumina come from shale, clay and bauxite. In addition, most of the raw materials contain iron oxide, magnesia, calcium sulfate, etc.

Lime: lime accounts for more than half of the cement ingredients. A sufficient amount of lime is the basis of producing enough silicate and calcium aluminate needed for cement. However, an excessive amount of lime will make cement not firm.

Alumina & Iron Oxide: alumina makes cement has the characteristic of fast solidification, and it reduces the temperature of clinker, accounting for 1/15 of cement ingredients. Iron oxides are the basis for the formation of tricalcium alumino-ferrite, which improves the hardness and strength of cement.

Magnesia & Calcium Sulfate: magnesium oxide exists in cement with very weak content. Once the content exceeds the upper limit, it will affect the performance of cement. The calcium sulfate is mainly from gypsum and has an effect of slowing down the solidification speed. In cement plant, gypsum is usually added in the clinker grinding process.

Type I: type I cement is the ordinary Portland cement. Its early cement strength performance is good, widely used in railway construction, bridge construction, military and general building construction, accounting for about 90 % of cement usage.

Type II: type II cement has the characteristic of moderate sulfate resistance. It produces less hydration heat, but its initial strength is slower than that of the type I cement. The type II cement is suitable for the construction of bridge piers and large dams.

Type III: type III cement has a high early strength. It can reach the strength of ordinary cement after 28 days in 3 to 5 days, so all kinds of projects that need to be completed in a short time will use this kind of cement, such as military construction, road laying and underwater engineering.

Type IV: the hydration heat during the hardening process of type IV cement is only about 70% of the ordinary cement, and its hydration heat development rate is kept within a very low limit, which can reduce the probability of concrete collapse. It is suitable for the construction of mega-projects.

Raw materials preparation: after materials are quarried, they need to undergo crushing, blending, grinding and storage four processes to finish the raw materials preparation before they are sent into the rotary kiln. In the first step, raw materials are sent into the crushing equipment in order to get an appropriate size, and mixed with each other to meet the requirements of clinker ingredients. Then we need to use the grinding mill to further pulverize them as long as they reach the qualified fineness that can be sent into the rotary kiln. After that, they will be stored in the silo waiting for further processing.

Clinker Calcination: clinker calcination is the most important stage during the whole Portland cement manufacturing process. It can be classified into the dry method and the wet method. The biggest difference is that in the dry method, raw mix is existing in the form of fine powder. While in the wet method, the raw mix is combined with water to form slurry before being sent into the rotary kiln. Anyway, they all need to be heated at a high temperature in the rotary kiln to produce chemical reactions with each other and finally forming clinker. After sintering, the clinker will have a high temperature. They will cool down at the end of the kiln firstly and then enter the cooler placed behind the rotary kiln for further cooling. When clinker drops to indoor temperature, it will go to the next step.

Cement Grinding: cement grinding is the final stage in Portland cement manufacturing. In this step, clinker will be ground in grinding mill to reach the qualified fineness of cement product. During the grinding, we usually add gypsum, fly ash and other raw materials into the cement to realize the different usage of cement. After all the above processes are completed, the cement will be packaged and sent to its destination.

AGICO is one of the leading cement plant and cement equipment suppliers in China. We provide high-quality rotary kiln, crushing mills, grinding mills, dust collector, etc. We also offer cement plant design service, equipment installation and commissioning service and after-sales service. If you are interested in our products, please feel free to contact us!

AGICO Group is an integrative enterprise group. It is a Chinese company that specialized in manufacturing and exporting cement plants and cement equipment, providing the turnkey project from project design, equipment installation and equipment commissioning to equipment maintenance.

cement production - an overview | sciencedirect topics

Cement production has undergone tremendous developments since its beginnings some 2,000years ago. While the use of cement in concrete has a very long history (Malinowsky, 1991), the industrial production of cements started in the middle of the 19 th century, first with shaft kilns, which were later replaced by rotary kilns as standard equipment worldwide. Today s annual global cement production has reached 2.8 billion tonnes, and is expected to increase to some 4 billion tonnes per year in 2050 (Schneider et al., 2011). Major growth is foreseen in countries such as China and India as well as in regions like the Middle East and Northern Africa. At the same time, the cement industry is facing challenges such as cost increases in energy supply (Lund, 2007), requirements to reduce CO2 emissions, and the supply of raw materials in sufficient qualities and amounts (WBCSD, 2008).

In this chapter, the environmental impact of cement production will be described. The chapter will first focus on the most common cementitious product: ordinary Portland cement (OPC) and will then evaluate the main perspective in terms of reduction of cement production s environmental impacts. To do so, we will describe the improvement perspective in the cement sector as well as the alternative products that could, at least partially, replace OPC.

Cement production is a thermal energy intensive process, which requires heating solid particles up to 1450C and cooling it down. The process generates hot and CO2 rich exhaust streams. Fin order to study energy efficiency of the process, authors like Mujumdar et al. (2006, 2007) developed detail models of process units, while others highlighted energy and exergy performances of plants (Kolip et al 2010). Some authors have studied the integration of cogeneration units in cement industry as an option of waste heat recovery (Wang et al 2008). The previously mentioned studies are considering, in detail, thermodynamic performances, but they are not investigating the heat integration inside the process. Some other authors, such as Murray et al (2008), Kaantee (2004), Mokrzycki (2003) have focused their analysis in the use of alternative/waste fuels, but they did not show the impact and the potential of these fuels on the heat integration between streams.

This paper explores the use of process integration techniques to improve the energy efficiency of cement plants, focusing on the dry route cement production and the integration of alternative fuels. Flow sheeting modeling, Pinch Analysis and mixed integer linear optimization techniques are applied to study an existing cement production facility.

Cement production is one of the largest industries in the world. Annual world production in 2013 was approximately 4 GT (of which, about half was in China). It is produced in kilns at around 1400oC (2500oF), and approximately 750 kg (1650 lb) of CO2 are released for each tonne (2205 lb.) that is made. This is 400 m3 (524 yd3) of gas; and CO2 normally forms only 0.04% of air. Cement production is responsible for around 7% of worldwide greenhouse gas emissions. The only larger contributors are electricity generation and transport.

Most of the CO2 released when cement is made comes from the chemical reaction. The limestone from which it is made is calcium carbonate, and when this is heated it gives off carbon dioxide, and forms calcium oxide. Thus, while some benefit has been obtained by making the process more energy efficient, there is little scope for any further reductions.

Numerous different solutions to this problem have been proposed, including carbon capture and inventing completely new cements; but the only effective method currently used to achieve significant reductions in greenhouse gas emissions is the use of cement replacements.

One process that has not been extensively investigated is carbon sequestration. In this process, the hydrated cement reacts with CO2 in the air, slowly reversing some of the processes that took place in the kiln when the cement was made (this is the carbonation process; it also causes reinforcement corrosion, see Section 25.3.2). It is estimated that this may reduce the carbon footprint of the cement industry by 35%.

Cement production is an energy-intensive process. The cost of energy constitutes more than 60% of the cost of the cement; hence cement plants have to consider minimizing the cost of energy when planning production. However, there are several challenging issues regarding the production plan. First, there are some operational constraints for the production process itself, such as keeping a proper level of inventory. Second, electricity prices are not fixed; they change on an hourly basis. Hence the cost of the electricity consumed may change substantially depending on the time of production. In this study, we developed a mixed integer programming model to minimize the cost of production (including energy, labor, and storage) by shifting working times to hours with low energy costs and trying to maintain activities during hours with high energy costs.

Cement production processes can be categorized as dry, semidry, semiwet, and wet processes depending on the handling of raw material before being fed to the rotary kiln. Nowadays, almost all new plants are based on the dry process and many old wet plants are also remodeled to dry or semidry processes. Dry cement manufacture has three fundamental stages: preparation of feedstocks, production of clinker, and preparation of cement [15,16].

Preparation of feedstock. This stage includes the process of siege, crushing, and prehomogenization. Typical raw materials used for cement production have 85% cayenne, 13% clay or blackboard, and under 1% each of materials such as silica, alumina, and iron ore. These feedstocks are crushed into particles with a diameter of less than 20mm and mixed with a prehomogenization pile [17].

Clinker production. As shown in Fig.6.6, the feedstock first enters the raw material to make a fine powder (raw feed), where 85% of the material is slightly smaller than 88m. Then, the feed is transferred to the homogenizing silos to impair the material difference. After that,the meal is thrown into the precalciner tower to start the chemical change to cement. Precyclone towers intermix with raw feed and almost 1000C of exhaust gas to recover energy, preheat feed, and initiate chemical reactions that result in cement. Gases straight from the kiln, but in precalciner facilities, gasoline, and air are provided by a combustion vessel inside the tower and kiln. Typically, 60% of burned calciner and more than 90% calcination have been reached before the material enters the rotary kiln. Inside the kiln, temperatures reach approximately 1400C to complete the process of chemical reactions and produce calcium silicates, called clinkers, with a diameter of 1025mm. The gas from the preheater tower is usually blended in a rawmill, which will help stabilize the future feedstock. After flowing through the rawmill, the gases are eventually released by a dust collector, which also obtains good particles when feedstuffs are milled. The dust will then be recycled into homogenizing silos and served as part of the kiln feed.

Preparation of cement. This stage completes the manufacturing process where clinker nodules are milled into cement. Following clinker milling, the cement is ready for use as a binder in various concrete mixes.

The cement production process, for example, starts with mining of limestone, which is then crushed and ground to powder. It is then preheated to save energy before being transferred to the kiln, the heart of the process. The kiln is then heated to a high temperature of up to 1480 degrees to convert the material to a molten form called clinker. The clinker is then cooled and ground to a fine powder with other additives and transferred to storage silos for bagging or bulk transportation (Portland Cement Association, 2014). The production of cement is either through the wet or dry process with the dry process as the preferred option because of the lower energy intensity. Cement production accounts for about 5% of total anthropogenic emissions (IFC, 2017). Cement-based structures constitute the largest surface area of all man-made structures (Odigure, 2009). World cement demand was about 2.283 billion tons in 2005, 2035 million tons in 2007, and 2836 million tons in 2010 with an annual estimated increase of about 130 million tons (Madlool, Saidur, Hossaina & Rahim, 2011; Odigure, 2009). World total cement production for 2016 was about 4.2 billion tons with emerging markets playing a dominant role (IFC, 2017). The energy intensity of cement production ranges from 3.6 to 6.5 GJ/ton depending on production process and location of the production (Hammond and Jones, 2011; Ohunakin et al., 2013; Worrell et al., 2000).

Cement production is one of the largest contributors to CO2 emissions. SCMs have been partially or completely used as replacement of cement or fine aggregates in construction to reduce the demand of cement and corresponding CO2 emissions (Al-Harthy etal., 2003; Babu and Kumar, 2000; Bondar and Coakley, 2014; Cheng etal., 2005; Jia, 2012; Khan and Siddique, 2011; Kunal etal., 2012; Limbachiya and Roberts, 2004; Lothenbach etal., 2011; Maslehuddin etal., 2009; Najim etal., 2014; Nochaiya etal., 2010; Siddique, 2011; Siddique and Bennacer, 2012; Toutanji etal., 2004). Some of the established SCMs are fly ash, silica fume, blast furnace slag, steel slag, etc. Pozzolanic materials, such as fly ash, steel slag, and cement kiln dust (CKD) when used as replacement to cement, improve the long-term performance of concrete as the pozzolanic reaction takes time. But, the early age strength of SCMs is a concern, as the reduction in cement content causes lesser hydration and, consequently, lesser formation of CSH gel (Lothenbach etal., 2011). The problem of low early strength of SCMs can be solved by using carbonation curing at early ages.

Apart from CO2 sequestration, carbonation curing has also been found to act as an activation mechanism for SCMs (Monkman etal., 2018). Many studies have tried to assess the effect of ACC on use of SCMs (Monkman and Shao, 2006; Sharma and Goyal, 2018; Zhan etal., 2016; Zhang etal., 2016; Zhang and Shao, 2018). ACC not only enhances the hydration degree of alternative cementitious materials but also improves the early age performance of concrete. Monkman and Shao (2006) assessed the carbonation behavior of blast furnace slag, fly ash, electric arc furnace (EAF) slag, and lime. All four materials reacted differently when subjected to carbonation curing of 2h. Fly ash and lime showed highest degrees of carbonation, followed by EAF slag, whereas ground granulated blast slag (GGBS) showed least reactivity towards CO2. Calcite was the major reaction product from fly ash, lime, and EAF slag, whereas aragonite was produced by carbonation of GGBS. Sharma and Goyal (2018) studied the effect of ACC on cement mortars made with CKD as cement replacement. ACC was found to improve the early age strength of cement mortars by 20%, even for mortars with higher CKD content. Several studies tried to assess the CO2 sequestration ability of steel slag binders (Bonenfant etal., 2008; He etal., 2013; Huijgen etal., 2005; Huijgen and Comans, 2006; Ukwattage etal., 2017). Presence of C2S component in steel slag makes it a potential cementitious material that could act as a carbon sink for CO2 sequestration (Johnson etal., 2003).

Zhang etal. (2016) in their study found that fly ash concrete was more reactive to CO2 as compared with OPC concrete. With the reduction in OPC content, a porous microstructure was generated due to insufficient hydration reaction. The enlarged distance between cement grains facilitated higher possibility of reaction with CO2, and hence, a higher degree of CO2 sequestration. The performance of SCMs subjected to carbonation curing is majorly dependent upon fineness of material and water content postcarbonation. Finer particle size of SCMs provides a higher specific area for effective carbonation reaction. Due to this, it was observed in many studies that concrete made with SCMs had better reactivity toward CO2 than OPC (Monkman and Shao, 2006). Water content postcarbonation also plays a dominant role in determining the performance of SCMs. Sufficient water content postcarbonation is necessary for complete hydration and pozzolanic reaction of SCMs (Monkman and Shao, 2006).

In Europe, cement production decreased by 26.9% from 1990 to 2012, whereas CO2 emissions decreased by 38.6%, showing an improvement in the cement production (CEMBUREAU, 2014). However, to reach the objectives of various sustainability programs, further efforts must be made in order to improve every step in the concrete production line. For concrete, the main solutions for reducing the environmental impact of modern construction are (Flatt et al., 2012):

Some other technical solutions to improve cement production are also of interest, including CO2 capture and storage. If this solution were to present a major impact on the final objective, it would need technological breakthroughs that are still in the research phase and are not planned to be ready for users before 2030, but they could potentially capture up to 45% of the CO2 produced by cement (IEA and WBCSD, 2010). By 2050 the baseline emissions will be 2.34 gigatonne (Gt) but will be reduced to blue emissions of 1.55Gt by the contribution of energy efficiency (10%), use of alternative fuels and other fuel switching (24%), clinker substitution (10%) and carbon capture and storage (56%) (IEA and WBCSD, 2010).

The worldwide use of blended cement in the production of cement is already a commonly used improvement, with significant investments for research made by cement producers (Table 15.7). Many blended cement types exist because of the great variability of usable SCMs. These cement types are produced by replacing part of clinker with SCMs, which leads to cement with unchanged or improved properties for both general and special applications. The same properties must be maintained; otherwise, for a functional unit (concrete beam) and on a product scale (cement), more cement may be necessary to obtain the same durability. Therefore the beneficial impact of replacing a part of clinker can be useless (Li et al., 2004). In the European context, binary cement incorporates up to 35% of each type of SCM even in the case of inert mineral fillers, and ternary cement uses up to 80% in mass replacement of clinker (EN 197-1, 2001). A final trend is the development of quaternary binder, but a lot of improvements remain necessary in order to ensure a better understanding of the interactions between clinker and SCMs.

As the CO2 resulting from the decarbonation of limestone during the calcination process is a fixed amount by clinker volume, the two major solutions are optimisation of the heating process to reduce the energy needed to reach 1450C and the use of blended cements.

The improvement of a specific burning process leads to no or very little change in the reduction of CO2 emissions, but a change from a wet process to a dry process with preheating and precalciner kilns can lead to significant improvements (WBCSD, 2013). The energy used by a wet kiln is estimated to be between 5.9 and 6.7GJ/tonne of clinker, whereas a kiln with preheating and precalciner kilns uses only 2.9 to 3.3GJ/tonne of clinker (reduction by 50%). Shifting the cement production from wet to dry with preheating and precalciner kilns can lead to a reduction of 20% (International Energy Agency, 2010) of the energy needed and 17% in the amount of CO2 emitted per tonne of clinker (Damtoft et al., 2008). It can be seen that the increase in part of the clinker produced by this technology could partially overcome the increase in cement production (WBCSD, 2013). These savings could be increased by the use of more alternative fuels (Nielsen and Glavind, 2007) (to coal, which actually accounts for 60% of the fuel used in cement production).

The use of SCMs in concrete is different from using them to produce blended cements. There is no guarantee on the potential strength achieved by a mixture of cement and SCM because of the great variability in the physicochemical properties of SCM. In order to control the amount used in concrete, use of SCM has been standardised through the k-value concept (Smith, 1967). This concept is based on the potential reactivity of each SCM, which helps in fixing a maximal replacement rate of cement to achieve the same mechanical and durability properties. The k-value for each addition differs depending on the type, on the concrete exposure conditions (frost, salt, sulphate, etc.)and on the local national standards. Depending on the type of SCM, the volume used and the targeted concrete strength, the savings in terms of CO2 emissions can be more than 20% (Table 15.9).

The previous solutions for improving the environmental aspect of concrete are widely used and remain of interest for further development, and some new, challenging solutions are also being studied but will need either breakthrough technology or huge investments in development. So far emissions of CO2 are inherent to cement production, so finding ways to prevent this gas from getting into the atmosphere need to be explored, as illustrated next.

Carbon capture and sequestration (CCS): This process consists basically of capturing the CO2 before it is released into the atmosphere and then compress it and store it underground (in mines, caves, oceans). Unfortunately, currently this process remains quite expensive and energy-consuming. Nevertheless, it is a new technology which can be improved in the future. On the other hand, it can also be argued that far from dealing with the problem, CCS is just a way to avoid the problem and leave it for later. Therefore it is totally in contradiction with sustainable development, which is defined by the Brundtland report (United Nations, 1987) as a development that meets the needs of the present without compromising the ability of future generations to meet their own needs.

Biofuel production: Although this approach is not yet totally explored, some researches have shown that captured carbon can be used in the production of algae that can then be transformed to biofuel, agricultural fertilizer or even animal protein (Potgieter, 2012).

Electrochemical carbon reduction (ECR): This process involves creating a reaction which will transform carbon into formic acid. This product is often used in the pharmaceutical industry. It is usually manufactured with high energy consumption but ERC requires less energy (Potgieter, 2012).

The first approach will be to reduce the volume of CO2 in the production of cement which is emitted into the atmosphere. But the most interesting solution in the short-term will be the development of alternative binders with a lower environmental impact, and some proposed solutions already provide excellent results on a laboratory scale or event in pilot projects (Aldred and Day, 2012; Duxson and Provis, 2008; Owens et al., 2010). Alkali-activated cements are aluminosilicatepozzolana-based materials (glass furnace slag, natural volcanic glass, manmade glass, fly ash, metakaolin). The activation occurs between the alumina-rich pozzolana and a strong alkali base, which dissolves the silicate and aluminate groups to form a cementitious gel to form the structure of the matrix. The so-called geopolymer is proven to have similar mechanical properties as cement-based concrete with a lower environmental impact (Duxson et al., 2007). This solution is already implemented in Australia by using fly ash and slag (Duxson and Provis, 2008). This solution is, however, hindered by some practical aspects, including the robustness of the design of the mix, the heat needed for a proper reaction to occur in a reasonable amount of time, the limited amount of available aluminosilicate compounds, the handling of the alkaline activator on the job site, the cost, and the environmental impact of the activator (Flatt et al., 2012).

Belite-rich cement, with a combination of calcium sulphoaluminate and calcium sulphoferrite, have been tested with success. Compared to ordinary Portland cement, belite-rich cement contains relatively higher belite (C2S) and lower alite (C3S) contents (Chatterjee, 1996). Belite-rich cement produces performances comparable to cement with the production of 2030% less CO2 (Li et al., 2007).

Some specially designed concretes have been developed with the eco-efficiency of products at a structural level in mind. This is particularly the case of HPC, including SCC (Hossain et al., 2013; Sonebi and Bartos, 1999, 2002). First, SCC will not act directly on the environmental aspect of sustainability, but rather on economical and societal aspects. When properly designed from the beginning, a construction made of SCC brings economic benefits by increasing the productivity because of the higher casting rate and the reduction in manpower which results in the elimination of vibration. This latter aspect also has a major societal aspect because it reduces the noise at construction sites and concrete factories and removes the risk of injury to workers related to crowded construction sites and vibration (Nielsen, 2007). The use of SCC in concrete factories (Yahia et al., 2011) can also be a solution for increasing mould service life and saving energy. In the case of concrete pipes, this reduction can be about 1.0GWh (De Schutter et al., 2010). Note also the reduced need for post-treatment of a surface by plaster, which accounts for 0.57kg of equivalent CO2 per m2, or by paint because of the better finish of concrete surfaces (Witkowski, 2015). This latter aspect can also increase the CO2 uptake by concrete carbonation because the concrete surface has no applied post-treatment. The major issue of SCC is that proportioning of a mix involves a significant amount of cementitious material in order to improve the workability of the concrete. This problem can be overcome with the development of high-performance chemical admixtures, use of high SCM content (Diederich et al., 2013), and an adequate selection of the granular skeleton of solid particles to achieve proper rheological properties of concrete. The latter approach has allowed the production of Eco-SCC with 40% fewer CO2 emissions than standard vibrated concrete, along with a 150-year service life (Mansour et al., 2013).

The development of high-strength concrete and high-strength, fibre-reinforced concrete is also a new approach to sustainability in construction materials. These concrete types are designed with a relatively greater amount of binder (cement and SCM) and chemical admixture, which achieves better performance than conventional concrete, including 316 times more compressive strength, 10 times more flexural strength and 10100 times more durability than conventional concrete does (Wang et al., 2015). These high performances allow a reduction in the size of elements for similar structural performance, therefore leading to a lower volume of concrete for the same structure. This reduction in volume can lead to a reduction of 65% in raw materials consumed, 51% in the primary energy used, and 47% in CO2 emissions (Batoz and Rivallain, 2009).

Currently in the United Kingdom, concrete debris is not sent to landfills but is treated so it can have a second life in the construction sector. Indeed, concrete is a material that can be fully recycled. In 2011 recycled and secondary aggregates represented about 5.3% of all aggregates used in concrete (Concrete Centre, 2011). This material is used mainly in road construction, but recycled concrete aggregates (RCA) can count for up to 30% of the aggregates in a concrete mix. In the United Kingdom recycled and secondary materials represent 28% of the total aggregates used in the marketplace, the highest in the Europe. The precast concrete industry provides greater opportunities for using recycled aggregates over to 20% (Concrete Centre, 2011). However, the following issues need to be considered when using RCA:

CO2 emissions from cement production are incurred through the consumption of fossil fuels, the use of electricity, and the chemical decomposition of limestone during clinkerization, which can take place at around 1400C. The decarbonation of limestone to give the calcium required to form silicates and aluminates in clinker releases roughly 0.53t CO2 per ton of clinker [8]. In 2005, cement production (total cementitious sales including ordinary Portland cement (OPC) and OPC blends) had an average emission intensity of 0.89 with a range of 0.650.92t CO2 per ton of cement binder [133]. Therefore, the decarbonation of limestone contributes about 60% of the carbon emissions of Portland cement, with the remaining 40% attributed to energy consumption, most of which is related to clinker kiln operations; the WWF-Lafarge Conservation Partnership [6] estimated that the production of clinker is responsible for over 90% of total cement production emissions.

In view of the fact that the requirement for decarbonation of limestone presents a lower limit on CO2 emissions in clinker production, and that there exist technical issues associated with the addition of supplementary cementitious materials (SCMs, including fly ash and ground granulated blast furnace slag), which restrict the viability of direct Portland cement supplementation by SCM above certain limits, the possibility to reduce CO2 emissions using Portland chemistry is limited. The WWF-Lafarge Conservation Partnership [6] expects that the emissions intensity of cement, including SCM, could be reduced to 0.70t CO2 per ton of cement by 2030, which still amounts to around 2 billion tons of CO2 per annum worldwide, even if cement production does not increase from its current level.

Fig. 10.6 shows the CO2 emissions of various binder designs as a function of Portland cement content. There have been a limited number of life-cycle analyses (LCA) of geopolymer technology. One reasonably extensive research program carried out in Germany [134] has provided information regarding the selection of precursors and mix designs for a range of geopolymer-based materials. However, geographic specificity plays a significant role in a full LCA, so there is the need for further studies considering different locations in addition to a wider range of mix designs spanning the broader spectrum of geopolymers. The main carbon-intensive and also the most expensive ingredient in geopolymer cement is the alkali activator, which should be minimized in mix design. McLellan et al. [135] provided further detail, while Habert et al. [136] concluded that geopolymer cement does not offer any reduction in carbon emissions; such a conclusion needs to be drawn with caution.

Sodium carbonate is the usual Na source for the production of sodium silicate. The different processes for conversion of Na2CO3 (or NaOH) and SiO2 to sodium silicate, via either furnace or hydrothermal routes, differ by a factor of 23 in CO2 emissions, and up to a factor of 800 in other emissions categories [137]. It is therefore essential to state which of these processes is used as the basis of any LCA. Moreover, the best available data for emissions due to sodium silicate production were published in the mid-1990s [137], so improvements in emissions since that time have not been considered. Sodium carbonate itself can be produced via two main routes, which vary greatly in terms of CO2 emissions. The Solvay process, which converts CaCO3 and NaCl to Na2CO3 and CaCl2, has emissions between 2 and 4t CO2 per ton of Na2CO3, depending on the energy source used. Conversely, the mining and thermal treatment of trona for conversion to Na2CO3 has emissions of around 0.14t CO2 per ton of Na2CO3 produced plus a similar level of emissions attributed to the electricity used. This indicates an overall factor of 510 difference in emissions between the two sources of Na2CO3 [138].

A commercial LCA was conducted by the NetBalance Foundation, Australia, on Zeobonds E-Crete geopolymer cement, as reported in the Factor Five report published by the Club of Rome [139]. This LCA compared the geopolymer binder to the standard Portland blended cement available in Australia in 2007 on the basis of both binder-to-binder comparison and concrete-to-concrete comparison. The binder-to-binder comparison showed an 80% reduction in CO2 emissions, whereas the comparison on a concrete-to-concrete basis showed slightly greater than 60% savings, as the energy cost of aggregate production and transport was identical for the two materials. However, this study was again specific to a single location and a specific product, and it will be necessary to conduct further analyses of new products as they reach development and marketing stages internationally. Fig. 10.6 shows a comparison of the CO2 emissions of four different E-Crete products against the Business as Usual, Best Practice 2011, and a Stretch/Aspirational target for OPC blends. It is noted that in some parts of the world (particularly Europe), some of the blends shown here in the Stretch/Aspirational category are in relatively common use for specific applications, particularly CEM III-type Portland cement/slag blends, but this is neither achievable on a routine scale worldwide at present, nor across the full range of applications in which Portland cement is used in large volumes.

Environmental impact of cement production is calculated based on the data provided by Ecoinvent (2012). Detailed information on the production process and on all inputs can be taken from Knniger et al. (2001). The functional unit is the production of 1kg of Portland cement strength class 42.5 (CEM I 42.5 R). Average fuel for clinker production is composed of 6.81103MJ natural gas (high pressure), 3.74104kg light fuel oil, 2.55102kg heavy fuel oil, 3.54102kg hard coal and 3.91103kg petroleum coke. In addition 5.80102 kWh electricity (medium voltage) is considered. Besides 0.912kg of Portland cement clinker, an input of 0.063kg gypsum (not balanced, origin from flue gas desulphurization), 0.025kg additional milling substances (not balanced as it is taken as waste without environmental burdens, e.g. dust from the cement rotary kiln, fly ash, silica dust, limestone) and 3.50104kg ethylene glycol (process material for grinding) is taken into account. A total energy for grinding and packing of 4.85102 kWh (electricity, medium voltage) as well as transport processes corresponding to 4.40103 tkm (lorry, 16t) is necessary. The production of 1kg Portland cement CEM I 42.5R yields an environmental impact of 0.833kg CO2-eq. (GWP100), 2.241108kg CFC-11-eq (ODP), 4.211105kg C2H4-eq. (POCP), 1.138103kg SO2-eq (AP) and 1.702104kg PO43-eq. (NP).

cement manufacturing: ways to reduce co2 emissions

However, cement manufacturing is linked inexorably to the ongoing phenomenon of climate change. Greenhouse gases like CO2 trap the suns heat and cause the average temperature to increase in the world. For the last one million years, the total CO2 concentration in the earths atmosphere averaged between 100 and 300 ppm(parts per million).

This equilibrium changed during the industrial revolution when the CO2 concentration started rising rapidly due to the increasing use of coal as a heating source. In the second half of the 19th century, the CO2 growth was exponential and as recently as September 2019, the total CO2 concentration in the world crossed 410 ppm, a value which is extraordinary in the history of the Earth.

In terms of weight, roughly 900 g of CO2 is produced as a by-product, for every 1 kg of cement produced. This is the uniqueness of the cement process, wherein CO2 is produced in substantial quantity, along with the main product (cement).

In the past, cement producers have targeted specific fuel consumption as a means of both improving the economy of operation as well as reducing CO2 emissions. Over the last thirty years, the specific fuel consumption of cement manufacturing has decreased by 40%, which directly reduces the CO2 emission by the same magnitude. Furthermore, coal, which is conventionally used for combustion, is increasingly being replaced by alternative fuels like Municipal solid waste (MSW), rubber tires, dried sewage sludge, etc.

In fact, it is the industrys best-kept secret that cement kilns are the last and best resort for recycling almost any waste produced in human societies. Since the kiln combustion happens at 1500 C, almost anything which has volatile matter could be burnt as an alternative fuel, and the burnt ash is a beneficial additive for the cement end product. Single-use plastics, which are becoming a pressing issue for the environment lately, can be a very good candidate for recycling in cement manufacturing. Additional research is needed to work out the intricate details of such plastic recycling.

Substituting conventional coal with alternative fuel achieves twin benefits by removing harmful waste from the environment as well as reducing process CO2 emissions in the cement kilns.The biggest stumbling block for wider usage of alternate fuels is turning out to be the cost of transportation. Cement manufacturing is a low margin process which cannot justify the added cost of transporting waste over long distances. It is, in fact, not economically viable to transport waste over 200 km for burning in cement kilns, assuming cement is priced normally as is done now.

Typically, governments have alleviated this issue by providing incentives to cement plants that process waste as fuel. The incentives vary from a straightforward payment per ton of waste burnt to the provisioning of carbon credits, which could be utilized towards the mandated emission norms. Perhaps an additional way that should be looked at by the governments is to encourage more private players in waste processing.

Private players could unlock more value in the waste streams by recovering useful minerals and transporting the remaining in an efficient way to the cement plants. For cement plants, this would ensure a stable and predictable supply of processed waste which is beneficial for their operation.

Nevertheless, in order to have a true zero-emission cement plant, more work needs to be done. As mentioned earlier, cement produces CO2 as a by-product, so, unless the CO2 is captured, stored or utilized, it is not possible to drastically reduce the emissions from the cement plant, CO2 capture being the easiest part of the process.

There are ready solutions available that can capture the emitted CO2 from the process: Oxyfuel combustion, chemical looping, all-electric process heating, etc. are some of the technologies that are in various stages of development for carbon(CO2) capture.

Storage of the captured CO2 is slightly more complicated and, presently, the most viable option seems to be the pumping of CO2 into used oil wells and other geological formations. The utilization of captured CO2 into other beneficial minerals is still in its early stages.

However, installing these technologies in a process like cement is not viable in todays economy. The average cost of production of cement is 58 /tonne. With a limited profit margin, investment costs and limited potential for realizing carbon costs, the currently viable selling price for cement is 78 /tonne.

Unfortunately, the operation of CO2 reduction using technologies available today costs roughly 60 /tonne of cement produced. This is comparable to the production cost of cement itself. In other words, a cement manufacturer might roughly spend the same cost for preventing CO2 emission as he spends on producing cement. Therefore, it is unviable in the present economic scenario for a sustainable cement manufacturer to realize a reasonable return on his investment.

This is because, at present, only the end product (Cement) is priced and sold by the manufacturer. The environmental cost of production is borne by society as a whole.This pricing structure needs to be inverted for the sustainable manufacturing of cement. The price of cement should include both the cost of cement manufacturing as well as the cost of not emitting CO2.

Establishing a market for CO2 is the most efficient way of calculating its cost. Initial steps along this line are already been taken in the form of carbon credits in the EU. This needs to be made more universal with strong regulation and covering all sources of carbon emission, both industrial and non-industrial. And this market should become global with all countries partnering and becoming part of it.

Alternatively, another localized solution is possible if the cement manufacturer is allowed to realize its manufacturing price including the cost of preventing CO2 emission. This could work by establishing a green cement similar to organic vegetables, priced higher compared to the normal variety:

Either way, the challenge of sustainable cement manufacturing is not technological but economic. The solution would be to re-align the economy by rewarding environmentally sustainable products which will ensure that cement production becomes more sustainable in the long run.

cement manufacturing process flow chart

Generally speaking, the cement industry production is Portland cement. Portland cement is a kind of delicate, usually gray powder, which consists of calcium (from limestone), silicate, aluminate and ferrite(clay).

Mentioned cement production people will say "two grinding burn",that means cement production process mainly includes three stages: raw meal preparation, clinker burning and cement grinding. The cement manufacturing process flow chart is shown as follows:

In the cement manufacturing process, most material must be broken, such as limestone, iron ore, clay and coal etc. Limestone is the main raw material for cement production, each producing a ton of clinker needs about 1.3 tons of limestone, more than 80% of raw material is limestone. Our company has a variety of limestone crushers for your choice, such as jaw crusher, impact crusher, cone crusher, VSI crusher and hammer crusher,etc.

According to availability and chemical composition, additional components could be added towards the raw mix. These are referred to as "Secondary" raw supplies.In the cement manufacturing process, each producing 1 tons of cement grinding material at least 3 tons (including fuel, clinker, gypsum, mixture and all kinds of raw materials).

The stability of raw material composition is the premise of clinker burning system. Raw meal homogenizing system stabilizes the raw ingredients into the cellar of the final control action. Clinker burning The rotary kiln is a cylindrical steel vessel, that is inclined for the horizontal at 2.5% to 4.5%. The kiln slowly rotates at 0.5 4.5 revolutions per minute to allow the material to tumble by means of the kiln to ensure adequate residence time in the kiln to accomplish the needed thermal conversion processes. The finely ground coal is fed for the firing end of the kiln exactly where it really is burned to create a gas temperature of around 2,000C. A preheater consists of several stages contained in a tall preheater tower, which utilizes the heat produced by the flame at the firing end from the kiln to preheat the raw supplies as they move by means of the various stages of the tower. Kiln systems with preheaters are a lot more fuel effective than extended kilns, making use of up to 50% less energy.

Once the clinker has formed, and has arrived in the firing end from the kiln, it drops into a planetary cooler, exactly where the clinker is cooled to roughly 100C above ambient. It's then transported to the clinker storage silos.

carbonation of concrete

This is essentially a reversal of the chemical process that occurs when making the cement used in concrete i.e. the calcination of lime that takes place in cement kilns, which accounts for the majority of concretes embodied CO2. Carbonation is a slow and continuous process that progresses from the outer surface moving inwards.

Over the lifecycle of concrete, carbonation will result in the reabsorption of around a third of the CO2 emitted when making cement, significantly reducing the whole-life CO2 footprint of both the cement and the concrete for which it is used. For this reason, it is important to ensure the environmental benefit of carbonation is accounted for when carrying out a life cycle assessment of concrete and buildings constructed from it.

If the carbonation front reaches steel reinforcement it can cause corrosion, so the mix design of structural concrete purposefully limits the rate of carbonation, preventing this problem from occurring during the life of buildings and infrastructure. There is, however, a greater degree of carbonation during the end-of-life stage, when concrete is crushed for reuse as an aggregate.

The crushing process substantially increases the materials surface area, allowing CO2 to be more readily absorbed. Although the deconstruction and demolition process at end-of-life can be comparatively brief, the resulting carbonation during this phase is significant.

In addition to direct absorption of atmospheric CO2, the newly crushed concrete aggregate also undergoes carbonation as a consequence of leaching from exposure to rain; a process that has been shown to significantly increase the rate of carbonation. Further CO2 uptake occurs during the materials secondary-life stage, when the recycled aggregate is used in a range of applications.

In lower strength concrete where no steel reinforcement is used, such as blocks, carbonation is more rapid during its service life, as CO2 can permeate the material more easily. In addition to the absorption of CO2, the carbonation process is also likely to increase the strength of these materials, and with no steel reinforcement present, their serviceable lifespan has the potential to be measured in hundreds rather than tens of years. The Pantheon in Rome, constructed around 1900 years ago provides demonstrable evidence of this.

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impact of weather conditions on concreting - ohorongo cement (pty) ltd

Concreting in adverse weather conditions such as hot weather, cold weather and windy conditions presents a unique set of challenges, which must be thoroughly planned for. These weather conditions can have negative impacts on the fresh concrete properties such as workability, as well as the hardened concrete properties such as strength and durability. Different parts of the world experience varied weather conditions, and ready-mix concrete producers as well as construction professionals need to adapt their construction material designs and construction methods to these weather conditions so that they can produce good-quality concrete despite the climatic drawbacks they face.

SANS 10100-2 defines hot weather as weather in which the ambient temperature exceeds 32C. Temperature above 25C may also be defined as hot weather if: the ambient relative humidity is low and the wind speed is high; the temperature of the concrete is high, or solar radiation is present. High temperatures increase the rate of the hydration reactions between the cement and the water, and thus the movement of moisture within and from the surface of the concrete. The following are the negative impacts of hot weather concreting:

Figure 1 below demonstrates the impact of high temperatures on water demand. It shows the amount by which the water content needs to be increased in order for the consistence of the concrete to be maintained.

Avoiding the negative impacts of concreting in hot weather requires a reduction in the temperature of the concrete by controlling or adjusting the concrete mix and/or by adjusting construction methods to ultimately reduce the temperature of the concrete. The following measures may be implemented when concreting in hot weather:

Cold weather is defined in SANS 10100-2 as weather in which the ambient temperature is less than 5C. Although extreme cold temperatures are not regularly experienced in Southern Africa, it is necessary to be aware of impacts of cold weather concreting for the few occasions that it may occur. Cold weather concreting negatively affects the concrete by freeze and thaw action. At early ages, if the water in the concrete freezes before the concrete has had an opportunity to set, or even after the concrete has set but before it has gained sufficient strength, then there will be an increase in the overall volume of the concrete due to the expansion of the water, especially in the capillary pores of the concrete. When thawing takes place, i.e. when the water unfreezes, the concrete will set with an enlarged volume of pores. These pores reduce the strength and durability of the concrete. If the freezing cycle takes place after the concrete has gained sufficient strength of about 3 to 5 MPa, then it can resist any possible negative impacts from the freezing. This is mainly due to the fact that a majority of the mixing water in the concrete mix has already been combined with the cement through hydration, and also because the concrete has a high resistance to the pressure of ice. The following measures may be implemented when concreting in cold weather:

Concreting during windy conditions has a negative impact on the curing of freshly placed concrete. High winds result in moisture loss and premature drying out of concrete, which interferes with the maintenance of continued hydration of cement required for the hardening of the concrete. Windy conditions encourage evaporation from the concrete, which further exacerbate the negative impact associated with concreting at high temperatures, discussed earlier. In coastal environments, concrete is also exposed to wind-driven, salt laden air, which can increase the chlorides content in concrete and lead to the corrosion of reinforcement in concrete and the subsequent cracking and spalling of concrete.

When concreting in adverse conditions such as hot weather, cold weather and windy conditions, certain precautions need to be taken to prevent the negative impacts associated with concreting in these conditions. Failing to address the possible negative impacts of concreting in these conditions may negatively affect both the properties of the fresh concrete and the properties of the hardened concrete. In particular, the water demand and the workability are largely negatively impacted by hot weather concreting. Hot weather concreting also reduces the later strength of concrete. Cold weather concreting results in air voids in the concrete due to freeze-thaw action, reducing the later strength and durability of concrete. Windy conditions may lead to cracking of concrete by drying out concrete prematurely and encouraging evaporation.

Click on the link below to download the informative types of cracks in concrete document. When working with concrete, the ease of placement is of great importance, and therefore adequate workability and consolidation of concrete often results in more water being added than needed for the hydration of cement. As the needed water is used in the concrete matrix as it hardens, it results in a reduction of volume, known ...

Ohorongo (Pty) Ltd. is one of the first of Namibia's cement manufacturers and owns one of the most modern cement plants in Africa. It was constructed over the course of two years by leading international engine...