1. Crushing Processing Limestone crushing generally requires only simple ore washing. Limestone generally adopts dry crushing technology. For metallurgical and road limestone, the ore can be crushed and screened. 2. Grinding Processing (1) Feeding system: Limestone enters the bucket elevator. And then it is sent to the raw material warehouse for grinding. (2) Grinding system: Material is sent to grind. After grinding, the finished product is collected by separator and collector, and is fed to screw conveyor. (3) Product conveying system: The finished products are conveyed to the finished warehouse. The excess gas is filtered by the dust collector. (4) Dust removal system: The whole system is equipped with three pulse dust collectors to ensure that the whole system is free of dust leakage. (5) Control system: The system is equipped with intelligent PLC control cabinet and upper computer.
In order to solve such problems as low production efficiency and difficult installation and maintenance, ZENITH developed a new generation of jaw crusher--- C6X Series Jaw Crusher. It is the most ideal coarse crushing equipment on current market because a
The demand for sand is increasing sharply while the quarrying of the natural sand is strictly limited in China because of environment protection. To bridge the gap between the lack of natural sand and the development of infrastructure, machine-made sand c
F5X Series Vibrating Feeder is designed and used in heavy-load operation. It boasts vibration intensity as large as 4.5G and extremely firm chute body structure. Its maximum capacity is 1600t/h, maximum feeding size 1.5m and volume of standard bin 25~45 m
Impact size reduction incorporates striking to pulverize material. The primary types of impact crushers include -- horizontal shaft impactors (HSI), cage mill pulverizers, and vertical shaft impactors (VSI).
For after-sales support, Stedman has a complete inventory of impact crusher parts and spares including breaker bars, wear liners, bearings, electrical components and shafts. Cage mill parts including sleeves, bands, and disks are stocked for quick cage assembly.
Impact size reduction incorporates striking to pulverize material. The primary types of impact crushers include -- horizontal shaft impactors (HSI), cage mill pulverizers, and vertical shaft impactors (VSI).
For after-sales support, Stedman has a complete inventory of impact crusher parts and spares including breaker bars, wear liners, bearings, electrical components and shafts. Cage mill parts including sleeves, bands, and disks are stocked for quick cage assembly.
Request A QuoteSince 1834 Stedman Machine Company has been a consistent leader in size reduction technology and industrial crushing equipment manufacturing. Our size-reduction equipment is designed to increase profits by maximizing the production of marketable product and reduce equipment down time.
Backed by more than 180 years of industry experience, our industrial pulverizing mills and crushing equipment provides efficiency, economy, and durability through consistent improvements in materials and design. With Stedman you are assured the highest levels of performance and the lowest possible maintenance.
Stedmans complete line of size reduction and crushing equipment (impact crushers, cage mills, and more) provides you access to the best equipment for the process, instead of modifying your process to fit the equipment.
As a premier industrial crushing equipment manufacturer, Stedman Machine Company provides consulting services, custom design and layout, project planning, full-scale testing and toll processing. Our 24 hour parts and service department along with our inventory of wear parts allow us to provide the fastest response time for parts and service.
Our extensive product line of industrial crushing and pulverizing equipment, industry-leading testing, unsurpassed experience, and dedication to you combine to make Stedman a leading crushing equipment manufacturer Your Solution to Size Reduction.
Lippmann offers a full line of Crushing, Screening, Stacking, and Specialty equipment used for the aggregate, mining, and recycling industries. Discover your perfect stationary, portable, and track equipment for your specific processing application.
Indonesia is the largest country in ASEAN with a land area of 1.919 million square kilometers and a marine area of 3.16 million square kilometers. The mineral resources are very rich in Indonesia, especially the limestone resource.
In recent years, the limestone mining industry in Indonesia has risen greatly, which not only drives the economic development of Indonesia, but also provides a large number of job opportunities, and brought huge business opportunities for the limestone crushing industry.
Indonesia's limestone reserves are about 34 billion tons, and proven reserves are about 28 billion tons, mainly distributed in the south and north of West Java, East Java, Papua in the east, Bali and Sumatra. It is the main non-metallic mine in Indonesia and ranks second after the coal mine.
On December 16, 2008, the Indonesian Parliament passed the new mining law. On January 12, 2009, the Indonesian President issued a new law No. 4 to replace Act No. 11 of 1967, which was implemented in the country for 41 years.
The most essential reform of the new mining law is that it replaces the long-term implementation of the Contract of Work (COW) and the coal mining enterprise work permit system (PKP2B) in Indonesia with a new licensing system.
In order to attract more funds to its domestic mining sector, currently, Indonesia government is launching a series of attractive policies and constantly revising and improving mining investment laws.
At present, the construction industry is Indonesia's second largest industry whose output value accounts for about 10% of GDP. The average growth rate had reached 7% between 2009 and 2013, which is the main driving force for Indonesia's economic growth.
The infrastructure is also the main part of the construction industry. The output value of infrastructure construction in 2013 accounted for 53.8% of the total output value of the construction industry.
Therefore, Indonesian governments have made infrastructure construction a priority for government investment. As the basic raw material for the production of cement, the limestone is only increasing in demand.
The Asia-Pacific mining risk return rankings published by Business Monitor International show that Indonesia and Australia rank first and second in the Asia-Pacific region with their rich mineral resources and stable investment environment.
The physical properties of limestone are small hardness and high brittleness with low silicon content and low abrasiveness. Therefore, the limestone is relatively easy to crush with low production cost.
According to different uses, limestone needs to be crushed into particles of different sizes: the products of 20-50mm size are mainly used for burning lime and the products of -20mm size can be ground into different meshes to meet the needs of various industries such as power plants.
Limestone is mined by blasting. Due to the blasting distance and other reasons, the particle size of the raw materials varies, and during the mining and transportation process, the the soil and other debris are included.
In summary, considering the advantages and disadvantages of several crushing methods, plus the physical properties of limestone, and to meet the maximum size of 20-50mm grain products, equipment with a relatively small crushing ratio should be selected. Thus, priority is given to the jaw crusher.
The initial plan is to use two-stage jaw crushers. The size of the discharge port of a section of jaw crusher can be adjusted larger slightly. After the crushing, the grade of +50mm is sent into the second-stage jaw crusher to reduce the fine powder. The two-stage crushers achieve a closed loop.
The limestone production line is a common production line in the heavy industry equipment, which is favored and chosen by many customers. The common limestone crushing production line includes vibrating feeder, jaw crusher, belt conveyor and vibrating screen.
The raw materials are transported from the warehouse through the ESW38095 vibrating feeder (-3mm purlin, adjustable). The waste is transported through the belt under the screen; the material above the screen is fed into the PE500750 jaw crusher, then transported into 4YK1848 vibrating screen for sieving;
Investors can get a good crushing effect by adopting the appropriate process configuration and equipment selection. In combination with the principle of "breaking more and less grinding" in the limestone production line, it is necessary to produce the best particle size in the stage of crushing limestone.
Henan Fote Heavy Machinery specializes in the production of mining equipment for 40 years. It has rich crushing experiences in the production of limestone mining equipment with advanced crushing technology and complete after-sales service, and is favored by domestic and foreign customers.
As a leading mining machinery manufacturer and exporter in China, we are always here to provide you with high quality products and better services. Welcome to contact us through one of the following ways or visit our company and factories.
Based on the high quality and complete after-sales service, our products have been exported to more than 120 countries and regions. Fote Machinery has been the choice of more than 200,000 customers.
Limestone is a sedimentary rock composed mostly of the mineral calcite and comprising about 15% of the Earths sedimentary crust. It is a basic building block of the construction industry (dimension stone) and a chief material from which aggregate, cement, lime and building stone are made. 71% of all crushed stone produced in the U.S. is either limestone or dolomite.
Limestone is a sedimentary rock composed mostly of the mineral calcite and comprising about 15% of the Earths sedimentary crust. It is a basic building block of the construction industry (dimension stone) and a chief material from which aggregate, cement, lime and building stone are made. 71% of all crushed stone produced in the U.S. is either limestone or dolomite. As a source for lime, it is used to make paper, plastics, glass, paint, steel, cement, carpets, used in water treatment and purification plants and in the processing of various foods and household items (including medicines).
Most limestone and dolomite are mined from open quarries, although in many areas economic and environmental considerations favor large-scale production by underground mining. The only carbonate materials not consistently recovered by surface or underground mining are shell products that are dredged from parts of U.S. coastal waterways.
The basic elements of surface mining are overburden removal, drilling, blasting and hauling ore to the crushing and processing plant. The selection of surface mining equipment varies with the particular requirements at each operation, including production capacity required, size and shape of the deposit, haul distances, estimated life of the operation, location relative to urban centers, and other social and economic factors. Other factors that must be considered in surface mining are the value of the products produced, location of competitive operations, and environmental and safety requirements associated with a particular deposit.
The basic operations in underground mining are drilling, blasting, loading and hauling, scaling and roof bolting. Drilling equipment includes horizontal drills and downhole track drills. This equipment is generally quite different from that used for surface mining and results in much smaller blast holes and a lower volume of rock produced with each blast. Other equipment required in the underground mine includes powder loaders, which are used to blow ammonium nitratefuel oil mixtures into the blast holes. Scaling rigs, which are used to remove loose rocks from the ribs and roof of the mine, and roof-bolting equipment may also be required in an underground mine.
Most underground limestone and dolomite mines are room-and-pillar-type operations, and many recover rock from both headings and benches. It is not uncommon for an underground limestone mine to have several benches and an overall mine height up to 30 m. Whereas the thickness of the deposit being mined is directly controlled by the thickness of the rock and related roof conditions, it is not uncommon for an individual heading to be 7.5 to 10.5 m high, and in some instances to reach as high as 15 m. Rooms are generally 13.5 to 15 m wide, which, depending on the type of drilling jumbo used, normally can be mined with one- or two-drill setups.
A V-type drill pattern is commonly used to maximize the amount of rock produced with each shot to reduce the amount of unbroken rock in the shot face. Roof scaling is normally required as a safety measure; roof bolting may or may not be required, depending on roof conditions at the individual mine. Loading and hauling equipment may include standard 22 to 45-ton haul trucks and correspondingly sized front-end loaders. In some mines, the loading equipment may be more typical of underground hard-rock operations and may include load-haul-dump units or other types of tramming equipment.
The largest use of lime is in steel manufacturing where lime is used as a flux to remove impurities such as phosphorus and sulfur. Lime is used in power plant smokestacks to remove sulfur from the emissions. Lime is also used in mining, paper and paper pulp production, water treatment and purification, and in wastewater treatment. It is used in road construction and traditional building construction.
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Jiangxi Shicheng stone crusher manufacturer is a new and high-tech factory specialized in R&D and manufacturing crushing lines, beneficial equipment,sand-making machinery and grinding plants. Read More
Many different industries have a solid foundation rooted in aggregates. Recognizing the extensive use of these aggregates motivates us to continuously create and improve our rock crushing equipment to help you increase production, decrease maintenance and improve the overall efficiency of your operation. When it comes to quality and efficiency, our rock crushers are perfect for the job.
Primary crushers are first in a typical size reduction operation. Primaries like our Mega-Slam horizontal shaft impactor are commonly used in the aggregates industry to handle large feed sizes.The Grand-Slam HSI is well suited as secondary crusher for aggregate production for a wide range of materials including limestone, frac sand, gravel, stone, and more. Tertiary crushers are commonly used in the aggregates industry for final particle shaping to increase cubicity, and to produce a product size beyond what is capable from a primary or secondary. This stage of crushing is typically accomplished using a vertical shaft impactor or cage mill.
Specialty uses of limestone include the manufacturing of pharmaceuticals, toothpaste, paint, paper, caulking, and glass. Flooring materials, carpet, and plastics all contain finely ground recycled limestone. Common antacids are virtually 100% finely ground limestone. Farmers can reuse limestone to neutralize acidity in their soils, saving money by reducing fertilizer use while improving crop yields.
The 4-Row Cage Mill allows Aglime producers to meet most state Aglime specifications in open circuit. It will economically produce Aglime to any specification for both large and small producers. The 4-Row Cage Mill feed does not have to be dry. Clogging, jamming and plugging are eliminated. Available with capacities as low as 5 TPH up to 100 TPH, the 4-Row Cage Mill produces consistent product quality.
Stedman Machine and Innovative Processing Solutions, an affiliate of Stedman, worked with Duff Quarry Inc. to incorporate two large industrial crushers to handle the size of limestone crushed annually. Their previous machines required a great amount of maintenance, but with Stedman machines, Duff Quarry Inc. spends less time fixing and more time crushing. With the installed plant and crushers, the quarry can produce up to 1.5 million tons of limestone a year running at full capacity.
Theres no reason to guess what method will meet your needs.The Stedman Testing and Toll Processing Facility is the place to test your material in our full size equipment. If it can be crushed, ground, pulverized or mixed, chances are weve done it. We have more than 10,000 test reports to help get you to the best solution quickly.
Test Before You Buy! Why Test? Stedman's testing facilities provide real-world conditions to view your materials being processed. Test out a range of different size reduction methods, saving you both time and money when selecting the proper size reduction method. Learn More
Stedman's testing facilities provide real-world conditions to view your materials being processed. Test out a range of different size reduction methods, saving you both time and money when selecting the proper size reduction method.
Stedman Machine Company is involved in professional organizations to better understand the knowledge and skills needed to serve our customers in the Aggregates Industry. These memberships give us better insight into the standards of the industry, updates to new and more efficient technologies and to the wants and needs of our customers. With the information obtained from our memberships, we can safely maintain the highest level of performance. Aggregate Industry associations include:
Wondering which grade of crushed limestone gravel is best for your driveway or household project? Check out the residential projects below and our guide to which types of Port Aggregate limestone aggregates are best-suited to your needs.
For garden or footpaths around your property, our pea gravel is finely crushed and feels pleasant underfoot. It comes in a soft blend of tan shades that make it a smart accent to an outdoor living space. We also recommend a larger grade of crushed limestone #57G is a good option as a base layer for walkways or landscaping filler around paving stones.
This guide introduced you to just some of the aggregates we have available. To find out more, visit the limestone page on the website or, to get expert advice on which product best meets your needs and vision, contact a member of our sales team.
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Arming yourself with a list of questions and a little prior knowledge goes a long way when hiring a driveway contractor or expert of any kind. If youre planning a concrete driveway project, before youRead more
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The drab old gray of plain concrete is definitely a thing of the past. From backyard patios to kitchen counter tops to foyers and lobbies, modern colored concrete often boasts distinctive designs and patterns orRead more
The main component of limestone is calcium carbonate (CaCO3) with a hardness of 3. Limestone is crushed to form limestone particles, which are further ground to form limestone powder, which is widely used in building materials, highways, metallurgy, chemical industries and other industries.
Limestone is rich in resources, and the grade of raw ore generally meets the requirements of various industrial sectors. Therefore, generally only simple ore washing is required, and no complicated beneficiation technology is required for purification.The processing of limestone is mainly crushing, grading and producing quicklime, slaked lime, precipitated calcium carbonate, ultra-fine (nano) calcium carbonate, carbon dioxide, etc.Limestone generally adopts dry crushing process. For metallurgical and construction use limestone, only the ore needs to be crushed and screened. If you want to further produce fine powder limestone products, use a jaw crusher, impact crusher or cone crusher to crush the raw ore and then use raymond mill to grind the product. The product fineness is 100-325 mesh. The specific processing flow is as follows :
The first stage: coarse crushingLarge pieces of limestone are uniformly fed by the vibrating feeder to the jaw crusher for coarse crushing. After the coarse crushed materials are screened by the vibrating screen, they are transported to the impact crusher by a belt conveyor.
The second stage: medium and fineAfter the coarse material is crushed and crushed by the impact crusher, the circular vibrating screen is used to screen the crushed materials, in which, the large particles are returned to the impact crusher to be crushe again; if finer products or shaping are required, the materials are sent to the sand machine machine to further fine crush.
The third stage: screeningThe medium and finely crushed stones are conveyed to the vibrating screen through a belt conveyor to screen out different specifications of stones. The stones meeting the particle size requirements are conveyed to the finished product pile, and the stones larger than the upper screen size are returned to the impact crusher through the belt conveyor.
1. The specific process is designed according to the parameters provided by the customer. This flowchart is for reference only.2. Eastman professional engineers will design matching material solutions for you according to the actual size of the granite material and the fineness requirements of different application fields. Please consult our online customer service.
Huaiying Fang, Dawei Xing, Jianhong Yang, Fulin Liu, Junlong Chen, Jiansheng Li, "Experimental Study on Limestone Cohesive Particle Model and Crushing Simulation", Advances in Materials Science and Engineering, vol. 2018, Article ID 3645720, 12 pages, 2018. https://doi.org/10.1155/2018/3645720
This study investigates the effect of impact velocity and particle size on crushing characteristics. We use a discrete-element method simulation and construct cohesive limestone particles with internal microinterfaces and cracks for impact crushing experimentation. The simulation model follows the same process as the impact crushing experiment. Results show that, after crushing at impact velocities of 30 and 40m/s, the simulated particle-size distribution curve matches experimental results as closely as 95%. For different particle sizes, results are more than 90% in agreement. These results indicate the feasibility of the cohesive-particle crushing simulation model. When the particle size is 15mm, an approximate linear relationship exists on impact velocity and crushing ratio. For a constant impact velocity, the particle size of 18mm results in the maximum crushing ratio.
The discrete-element method (DEM) is an effective numerical simulation method for investigating crushing particles . For DEM numerical simulation of particle breakage, it is necessary to construct a model of the materials particle mechanics. The quality of the model strongly affects the simulation results . In the mineral ore field, Potyondya and Cundall built a DEM modelbased on a bonded particle modelthat simulated rock crushing . The rock is filled with assembly of spherical particles of different sizes, and the contact point is added with the parallel bond. Bonding differently sized particles into cohesive particles. The cohesive particles are used in the impact crushing experiment. Schubert et al. showed that experimental results had similarities with DEM simulations, proving the feasibility of this approach . Price et al. proposed a filling method using the particles mesh vertices to automatically derive the 3D surface, thereby converting four points into a sphere . However, the random sampling technique required to select four points from a large number of mesh vertices affects the computational efficiency. Al-Khasawneh proposed a new model based on the DEM . In simulations and experiments, their model avoided the problems caused by calculating too many cohesive particles. However, it also ignored the changes of micromorphology in the grain-crushing process.
Jiang et al. developed the numerical model of rock fragmentation via waste-jet impact based on the finite-element method. The results showed that the theoretical scopes of the crushing and damage zone were slightly smaller than those of the numerical method because the stress wave reflection and superposition were ignored in the developed theoretical model . Quist and Evertsson built an ore particle model for simulating cone crushing in a virtual environment with a collection of particles using a bimodal model . Lei built a cohesive-particle model with a single particle that can dynamically simulate the whole process of a jaw crusher crushing the material . Li established a model of a collection of particles to simulate asphalt pavement. He used uniaxial compression and indirect tensile test parameters to calibrate the DEM, improving the established theories of milling operations . The internal parameters of the above mode only be given one group of bond parameters, and more researches only are carried out compression crushing. It is difficult to reflect the internal strength of many kinds of minerals binding the surface and different minerals in the ores. Due to particle breakage and fracture that can only be fully understood at the particle scale, DEM has been widely used in the past few years . In this paper, we constructed a cohesive-particle model with internal microinterfaces and cracks to simulate the crushing process of a single material. The particle size distribution after crushing was analyzed. The real crushing ratio and sand forming rate were compared and analyzed.
HertzMindlin (no slip) is a DEM simulation model with the normal force based on Hertz contact theory and the tangential force based on the work of MindlinDeresiewicz. The contact between granular cells is modeled by a spring-damping system. The spring represents the elasticity of the unit. Damping is force attenuation or object in the energy dissipation of the movement. The damping represents the inelasticity, and the sliding block with friction coefficient represents the friction between elements. The contact model between particle elements is shown in Figure 1. The contact model is efficient and accurate for calculation of the forces .
From Hertz contact theory , the normal force between the particles iswhere is equivalent Youngs modulus; is equivalent radius; is normal overlap; , , and and , , and are Youngs modulus, Poissons ratio, and the radius of the contact sphere, respectively.
The tangential force between the particles iswhere is the shear stiffness; is the tangential overlap; is the equivalent shear modulus; and are the center coordinates of A and B of particle units, respectively; and d is the distance between the centers of the two particle units.
The contact stiffnesses between two particles are modeled as a set of elastic springs with a constant normal and shear stiffness at the contact point (Figure 2). When two particles overlap, a normal and shear contact force develop at the contact point, causing a relative motion to occur between two balls during each calculation step. Parallel bond replaces cohesion between different tissues with polymerization in rock material particles. Therefore, the numerical calculation model of the crushed rock material particles, the cohesive particle model, is obtained.
The HertzMindlin with the bonding contact model can use a finite bond force to calculate the bonded particle model. The bonding force/moment is an additional HertzMindlin force. This model is especially suitable for simulating the fracture failure of concrete and rock-like materials [21, 22].
The interaction between particles is calculated by the HertzMindlin contact model using DEM software before the particles are bonded together during bond generation. After bond generation, the force ()/torque () on the particle is set to 0 and (5)(8) are calculated:where is the bonding radius; and are the normal stiffness and tangential stiffness, respectively; is the time step; and are the normal velocity and tangential velocity of the particle, respectively; and are the normal angular velocity and tangential angular velocity of the particle, respectively.
Owing to the complex internal structure and diverse composition of rock, the bond strength differs even between different samples of the same mineral. Using the HertzMindlin with the bonding model, we use multiple-strength bond keys to distribute bonds randomly to construct the initial defects in the interior of the particles. The particle-ball model is then divided into four parts. The shared surfaces of each part represent internal cracks and can simulate the differences in cohesion between both similar and different minerals. The discrete-element model of rock particles needs to determine the physical parameters and contact parameters. The physical parameters and contact parameters of limestone discrete-element model are determined through a series of experiments. The results are shown in Tables 1 and 2.
The cohesive-particle model is established with internal microinterfaces and cracks as shown in Figure 3. In Figure 3(a), four different color combinations red-dark green, blue-light green, green-brown, and pink-black represent the distributions of four same-sized particle types. The bonding surface of each structure is the internal crack of the particle, which is composed of two small particles of different sizes. The different cohesive force between small particles and the initial crack in the cohesive particles is set to a smaller bond strength. In Figure 3(b), the different colors, lengths, and thicknesses of the link bar indicates the different bond strength of bond keys.
The bonding surface of the initial crack in the material is easily broken owing to the mechanical properties of rock. We determine a set of appropriate parameters through the impact crushing experiment and simulation experiment. The type and value of the contact model parameters are shown in Table 3.
Figure 4 shows a schematic of the single-particle impact crushing experiment. The material particles are accelerated by high-pressure gas and impact a stationary plate. We obtain the required particle impact velocity by adjusting the pressure. The impact velocity is calculated using a high-speed camera to measure the distance between points A and B and the time difference between the two frames. After collecting the crushed material, the size distribution is obtained. For material less than 4.75mm in diameter, standard sieves are used to screen the distribution of particle sizes. For larger particles, a video size-detection system is used. The impact simulation experimental device is shown in Figure 5. In the experimental device, the MROM110 CMOS high-speed camera and the MACRO100F2.8D manual focus lens are used. The shooting rate can reach 10,000frames/s, which can fully capture the position information of high-speed shot particles. Since the camera's light-receiving rate is relatively low at high resolution, a carbon lamp is added to fill the camera to achieve a clear speed image. The light source used in this test is a 1000W carbon lamp. The high-pressure gas in the high-pressure gasholder is equivalent to the power system of the experimental device, and the limestone driven by the high-pressure gas is sufficiently accelerated in the acceleration pipeline to enter the crushing chamber and hit the impact plate of the crushing chamber at a higher linear velocity. The impact plate has a speed acquisition window on the surface of the crushing chamber and is sealed with bulletproof glass. The speed of the limestone particles before impact can be calculated from the pictures taken by the high-speed camera. The aggregated particles can also be collected efficiently after crushing. The crushed particles are collected and processed by a combination of mechanical screening and image processing to calculate the mass distribution and the true crush ratio of the particle size interval.
In this paper, we construct cohesive-particle models using a variety of bond-key combinations based on previous research on the parameters of a single bond key. DEM is used to simulate impact experiments with different velocities and different particle sizes. The simulation of the impact process is shown in Figure 6. The 15mm model cohesive particle with internal initial crack and microstructure is impacted at different velocities, and an image size-detection system is used to measure the distribution of particles size after crushing. In addition, at 45m/s, different sizes of limestone cohesive particles are modeled and the experiment is repeated. The limestone material with a particle size of about 15mm is rounded, and then a single-particle active impact crushing experiment is performed. A limestone crushing process is recorded using a high-speed camera (Figure 7).
We accelerate the 15mm single-particle limestone material with different air pressures to reach the desired impact velocities. We then observe the particle-size distribution after crushing and analyze the degree of fragmentation and crushing effect. After 10 crushing experiments, we take the crushed limestone and calculate the grain mass proportions using sieve screening and the image size-detection system. The DEM simulation is used to count the bonded-particle aggregate after each particle is completely crushed. The cohesive particles model diameter of the simulation experiment is 15mm. The particle-size fractions are determined using image processing.
Impact velocities of 20m/s, 30m/s, 40m/s, and 50m/s are used to crush materials with similar particle sizes, and the granularity characteristics are analyzed. With increasing impact velocity, particles are broken further. The characteristics of the particle-size distribution are analyzed.
For impact velocity 20m/s, ore particles break from the middle into two pieces. When impact velocity is increased to 30m/s, the particles break into 3-4 parts. For impact velocity 40m/s, the particles break into 4-5 parts. The particle-size distribution of the simulated fracture is close to the real crushing condition, so the internal structure of the initial microstructure and the crack of our particle model simulates the impact crushing process well. For impact velocity 50m/s, the particles break into 7-8 parts, similar to the simulation. The particles with particle size 4.7513.2mm accounts for the majority; fewer particles are <2.36mm or >13.2mm in diameter. The particle-size distribution curve is close to a normal distribution. When the particle size is almost the same, Figures 811 show that the morphology of the broken material is similar. With increasing impact velocity, the particle-size distribution curve is skewed to the left overall, the grain size is decreased, and the particle-size distribution curve is closer to a normal distribution after breaking. The simulation results are close to the experimental results.
To investigate the relationship between impact velocity and particle-size distribution, the present study uses experimental and DEM simulation data. A particle diameter of 15mm is chosen for the single-particle impact crushing experiment, performed at different impact velocities. The real crushing ratio i is the ratio of the arithmetic mean particle size of the particles before crushing to the arithmetic mean particle size of the particles after crushing. The formula is as follows:
The purpose of mechanical sand is to increase production for industrially produced sand, and the particle size should be <4.75mm. Thus, it is important to study the particle-size statistics. The sand forming ratio formula is as follows:where is the mass of the particles smaller than 4.75mm after crushing and is the total mass of aggregate after crushing.
Figure 12 shows the comparison of experimental and simulation real crushing ratios for limestone of particle size 15mm at an impact velocity of 2050m/s. The average particle size of the ore materials for the experiment and the simulation was obtained by the weighted arithmetic average method and used to calculate the real crushing ratio. With increasing impact velocity, the real crushing ratio and sand forming ratio increases proportionally. This relationship has the same trend for simulation and experimental results. This shows that the establishment of the internal initial crack and the microinterface of the particle model are reasonable.
For dynamic loads such as impact crushing, the initial particle size has a significant effect on the physical properties of the particles, which are nonuniform solids with many internal cracks. The random distribution of the cracks determines if the local macroscopic strength of the particle is less than the nominal strength. The larger the particle, the more the internal cracks, and the more likely it is to be damaged owing to a weak point.
To standardize comparisons of fragmentation of different particle sizes, we introduce the concept of unit impact crushing energy to account for energy consumption per unit volume and crack density. Hu et al. discussed the relationship between energy consumption and size distribution of original coal particles and crushing products, and the results show that there is an optimum size of the original coal particle at which the specific impact energy reaches minimum . Guo et al. set up the relation models between coefficient of energy utilization and the degree of crushing, as well as the models between the coefficient and input energy by simulating the fragmentation process of rock blasting . To study the effect of particle size on energy consumption per unit volume and the fragility of the particles, we mill limestone particles into 10mm, 14mm, 18mm, and 22mm balls using a small round mill (DM-III Abrasion Tester). Then, we set the impact velocity to keep unit impact crushing energy in a similar range and use the DEM to simulate the process of the experiment. The cohesive particles model diameters are 10mm, 14mm, 18mm, and 22mm in the DEM simulation experiment:where is the unit impact crushing energy, is the impact crushing energy, is the particle mass, is the particle volume, is the impact velocity, and is the particle density.
In the DEM simulation, 10mm, 14mm, 18mm, and 22mm balls are accelerated to 45m/s to make their unit impact crushing energy consistent. Using statistical methods, we analyze and compare the particle-size distributions after crushing as shown in Figures 1316.
In the experiment, for the 14mm material particle size, the material breaks into 4-5 parts, similar to the simulation results. At impact velocity 45m/s, particle size 4.7513.2mm accounts for most material, and fewer particles have diameters >13.2mm or <2.36mm. Figures 1316 show the particle-size distribution curve after experiment and simulation under the same impact velocity. When unit impact crushing energy of the material is kept constant, the particle-size distribution curve is shifted to the right as the particle size increases, the fine aggregate gradually decreases, the larger particle size increases, and the probability density curve after crushing tends to a normal distribution. This simulation result is similar to the experimental result.
To investigate the relationship between particle-size distribution and particle size after impact crushing, the present study uses experimental and DEM simulation data. Limestone single particles with diameter 1022mm are used in the impact crushing experiment at the same velocity, to maintain constant unit impact crushing energy. From the experiment and simulation results, we obtain the average particle size of the crushed material and calculate the crushing ratio. The curve relationship between the crushing ratio and the particle size is established; the results are shown in Figure 17(a). To calculate the broken sand ratio, we establish the particles size and sand ratio curve and compare with the results of the impact crushing experiment as shown in Figure 17(b).
Figure 17(a) shows the comparison of experimental and simulated crushing ratios of 1022mm limestone particles at 45m/s. The average particle size for the experiment and the simulation was obtained using the weighted arithmetic average method and used to calculate the crushing ratio. As particle size increases, the crushing ratio first increases to a maximum and then decreases. Figure 17(b) shows the inverse proportional relationship between the percentage of sand formation and the particle size of materials after crushing. The trend is the same for both the simulation and the experiment, showing that the particle model with the internal initial crack and microstructure is reasonable.
In this paper, we constructed a cohesive-particle model with internal microinterfaces and cracks using a DEM simulation. After simulating the impact crushing process of the single-particle material and using experiments to verify the rationality of the model, we reach the following conclusions:(1)The proposed model can simulate the internal defects of rock materials, and the strength can be adjusted according to different materials. The model is suitable for the impact fracture of anisotropic brittle materials and is a modification of the bonded particle model.(2)For constant particle size, there is a linear relationship between impact velocity and crushing ratio. Sand formation rate increases as impact velocity increases.(3)Up to a certain impact velocity, there is an optimum particle size, which has the highest degree of fragmentation and the maximum crushing ratio.(4)For constant unit impact crushing energy, there is an approximate inverse relation between sand formation rate and particle size. The entire particle-size distribution curve is shifted to the right with the increasing particle size. The proportion of fine aggregate to larger particles gradually decreases.
The cohesive-particle model with internal microinterfaces and cracks is feasible for simulating the impact crushing process of limestone particles. The DEM has an important application value in the simulation of material fragmentation and is used as the basis for a new method for further research on the efficiency of impact crushing, consumption of crushing energy, and material characteristics after crushing.
This work was financially supported by the International Science and Technology Cooperation and Exchange Program in Fujian Province (2018I1006), Major Project of Industry-University-Research Cooperation in Fujian Province (2016H6013), and the Subsidized Project for Cultivating Postgraduates Innovative Ability in Scientific Research of Huaqiao University (1611403006). The project received research start-up fee from Huaqiao University (17BS305) and Fujian Natural Science Foundation Project (2017J01108).
Copyright 2018 Huaiying Fang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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The geographical part of the world consists of different types of rocks, which have found profound uses in human life. An example of such rocks is the limestone. The limestone rock falls under the category of sedimentary rocks, with its main composition being calcium carbonate element. It is mostly found in warm and shallow marine water bodies. This calcium carbonate (CaCO3) rock makes a major part of human life.
This is the most common use of limestone. After quarrying, the limestone is sliced into slabs or blocks of predetermined sizes. These slabs and blocks can then be used for the construction of things such as sculptures, tiles, pyramids, or even stair treads.
Limestone is made up of calcium carbonate compounds. Calcium carbonate is an essential compound in the manufacture of agricultural lime, also known as Aglime. This agricultural lime is used in the neutralization of soil acidity. Aglime also frees us important soil minerals, such as different types of phosphates.
When limestone is grounded, it forms small filter stones that have cleansing and purifying properties. These filter stones can be used in sewage systems to filter and treat wastewater. Also, lime, made from limestone, can be used for neutralizing acids and treating contaminated water supplies.
Crushing limestone results in the production of small-sized fine powders. These powders can be used as fillers in manufactured products. Industries that use limestone fillers in their products include the paint, carpet, rubber, and plastic industries.
Asphalt roofing shingles are best known for their good quality and high resistance to heat and harsh weather conditions. Their high resistance quality is because their surface coating is made using crushed limestone.
Limestone that has been crushed can be used to refine and smelt metals. When used for smelting, the calcium carbonate rock reacts with impurities in the metal, combining with them, and the combination removed in the form of slag.
Limestone is also used to manufacture cement, which is used for the construction of houses. To produce cement, the rock is combined with other materials, such as sand, after which the mixture is put in a kiln and heated.
If hens are to lays eggs with strong shells, they need to take in enough calcium carbonate. Limestone is used to manufacture supplements for chickens, rich in calcium carbonate. These supplements (chicken grits) can also be given to dairy cows to boost their calcium levels.
Mine safety dust is commonly referred to as rock dust. It is usually white and is available in powder form. This dust is used to spray coal surfaces that have been exposed, improving illumination in the process, and reducing the levels of coal dust released into the air. Pulverized limestone is used for manufacturing this essential powder dust.
If you own a lawn and wish to increase the soils bacterial activity, then you would do well to use pulverized limestone. This limestone promotes the breakdown of compost manure and organic matter, which in turn improves the soil porosity and boosts the circulation and absorption system of the soil. The result is a good soil structure for your lawn.
Golf grounds are designed with special kinds of putting grass, which require careful and proper management. These kinds of putting grass only survive at specific soil pH levels. Applying lime on these types of soil helps to maintain the ideal pH levels, hence, maintaining the golf grounds in the long run.
During the winter, horse owners tend to keep the barns closed, to keep their horses warm. Closing barns reduces their ventilation and could lead to increased levels of ammonia in horses. Placing lime in the barns helps to absorb the ammonia, keeping the horses healthy.
Cats urine has some amounts of ammonia. When the cat is exposed to ammonia, even smaller amounts, it can cause breathing problems in the long run. Limestone is, therefore, used as a component of cat litter to absorb the harmful ammonia released and keep the cat healthy.
Calcium carbonate present in limestone is a soft compound. Its soft nature gives its application in the making of beautiful carvings and statues. Furthermore, limestone is resistant to acidity, so using it to make statues ensures that these remain highly durable for a long time.
Limestone is used as a major raw material for manufacturing calcium oxide, also known as quicklime. Quicklime is used in the making of grass and porcelain. It can also be used for purification purposes.
Limestone is used as one of the reagents in the desulfurization process. In this process, the limestone reacts with sulfur dioxide in the air. Since sulfur dioxide causes air pollution, its reaction with limestone helps to minimize air pollution.
Limestone is usually added to pipes carrying purified water. The limestone works to increase the alkaline levels of these pure waters, at the same time restoring the essential mineral levels. This helps to protect the pipes from corroding.
When most people hear of limestone, they think of cement and buildings. However, this article has helped you broaden your knowledge of the various uses of limestone. It is not just a stone used as a building material; it is a building component for many other important products.