Iron is a metal in the first transition series and forms much of the Earths outer and inner core. Irons very common presence in rocky planets like Earth is due to its abundant production as a result of fusion in high-mass stars. This is where the production of nickel-56 (which decays to the most common isotope of iron) is the last nuclear fusion reaction that is exothermic.
Like other Group 8 elements, iron exists in a wide range of oxidation states, although +2 (ferrous) and +3 (ferric) are the most common. Elemental iron occurs in meteoroids and other low-oxygen environments but is reactive to oxygen and water. Fresh iron surfaces appear lustrous silvery-gray but oxidize in normal air to give iron oxides, also known as rust. Unlike many other metals which form passivating oxide layers, iron oxides occupy more volume than iron metal. Therefore, iron oxides flake off and expose fresh surfaces for corrosion.
Pure iron is soft (softer than aluminium) but is unobtainable by smelting. The material is significantly hardened and strengthened by impurities from the smelting process, such as carbon. A certain proportion of carbon (between 0.2% and 2.1%) produces steel, which may be up to 1,000 times harder than pure iron. Crude iron metal is produced in blast furnaces where ore is reduced by coke to pig iron, which has a high carbon content. Further refinement with oxygen reduces the carbon content to the correct proportion to make steel. Steels and low-carbon iron alloys with other metals (alloy steels) are by far the most common metals in industrial use due to their great range of desirable properties and the abundance of iron.
Iron chemical compounds, which include ferrous (Fe2+) and ferric (Fe3+) compounds, have many uses. Iron oxide mixed with aluminium powder can be ignited to create a thermite reaction used in welding and purifying ores. Iron forms binary compounds with the halogens and the chalcogens.
Aside from the ferric and ferrous oxidation states, iron also occurs in higher oxidation states. An example is the purple potassium ferrate (K2FeO4) which contains iron in its +6 oxidation state. There are also many mixed valence compounds that contain both iron(II) and iron(III) centers, such as magnetite and Prussian blue (Fe4(Fe(CN)6)3). The latter is used as the traditional blue in blueprints. Prussian blue is also used as an antidote for thallium and radioactive cesium poisoning.
The iron compounds produced on the largest scale in industry are iron(II) sulfate (FeSO47H2O) and iron(III) chloride (FeCl3). The former is one of the most readily available sources of iron(II). Iron(II) compounds tend to be oxidized to iron(III) compounds in the air.
Iron reacts with oxygen in the air to form various oxide and hydroxide compounds; the most common are iron(II,III) oxide (Fe3O4) and iron (III) oxide (Fe2O3). Iron(II) oxide also exists, although it is unstable at room temperature. These oxides are the principal ores for the production of iron. They are also used in the production of ferrites, useful magnetic storage media in computers and pigments. The best known sulfide is iron pyrite (FeS2), also known as fools gold owing to its golden luster. The ferrous halides typically arise from treating iron metal with the corresponding binary halogen acid to give the corresponding hydrated salts. Iron reacts with fluorine, chlorine, and bromine to give the corresponding ferric halides. Ferric chloride is the most common.
Iron plays an important role in biology, forming complexes with molecular oxygen in hemoglobin and myoglobin. These two compounds are common oxygen transport proteins in vertebrates. Also, iron has an essential role in the formation of deoxyribonucleotides by ribonucleotide reductase. Iron is also the metal used at the active site of many important redox enzymes dealing with cellular respiration, oxidation, and reduction in plants and animals.
Iron ore is used primarily in the production of iron. Iron is used in the manufacturing of steel. Steel is the most used metal in the world by tonnage and purpose. It is used in automobiles, airplanes, beams used in the construction of buildings and thousands of other items.
Iron ore is used primarily in the production of iron. Iron is used in the manufacturing of steel. Steel is the most used metal in the world by tonnage and purpose. It is used in automobiles, airplanes, beams used in the construction of buildings and thousands of other items.
Iron ore are the rocks or minerals by which metallic iron is derived. Iron ores that carry a high quantity of hermatite or magnetite can be fed directly into blast furnaces in the iron production industry.
Iron ore are the rocks or minerals by which metallic iron is derived. Iron ores that carry a high quantity of hermatite or magnetite can be fed directly into blast furnaces in the iron production industry.
The business of mining iron ore is a high volume, low margin industry because of the low value of iron. The transport of iron ore by way of railway or freight requires a highly stable infrastructure for the mining production to be economically feasible. As a result, the mining of iron ore has remained in the control of a few major companies.Iron ore is the main ingredient in steel, which makes up 95 percent of the metals used in the world per year. Two billion metric tons of raw iron ore are produced in a year. The world's largest single producer of iron ore is Brazilian mining company Vale, which produces over 350 million tons of iron ore annually.
The business of mining iron ore is a high volume, low margin industry because of the low value of iron. The transport of iron ore by way of railway or freight requires a highly stable infrastructure for the mining production to be economically feasible. As a result, the mining of iron ore has remained in the control of a few major companies.
Iron ore is the main ingredient in steel, which makes up 95 percent of the metals used in the world per year. Two billion metric tons of raw iron ore are produced in a year. The world's largest single producer of iron ore is Brazilian mining company Vale, which produces over 350 million tons of iron ore annually.
Iron is the most important metal in heavy industries, Iron is the fourth most abundant element in earths crust after oxygen, silicon and aluminum as it forms (5.1 %) of the mass of the earths crust and this mass increases gradually as we come close to the center of earth, Iron occurs only in the form of pure metal (90%) in meteorites.
Iron ( 26Fe: (18Ar), 4S2, 3d6 ) is found in the earths crust in the form of natural ores which contains different iron oxides mixed with impurities such as Silica (SiO2), (Al2O3), CaO, and MgO, and some harmful impurities such as s, p and As, The suitability of the ore in the extraction of iron economically depends on three factors which are:
The ore is Hematite, chemical name is iron III oxide, the chemical formula is Fe3O4, It has a blood red colour, it is more easily reduced, Iron is from 50-60 %, place of deposits is Oasis area (western desert) and western part of Aswan.
The ore is Limonite, chemical name is Hydrated iron III oxide, the chemical formula is 2Fe2O3.3H2O, It has a yellow hydrated oxide & it is easily reduced, Iron is from 20-60 %, place of deposits is Oasis area.
Magnetite is a compound behaves as a mixture of two oxides: FeO (iron II oxide, the oxidation number of iron = +2), Fe2O3 (iron III oxide, the oxidation number of iron = +3), so, the oxidation number of Fe in Fe3O4 is (+2, +3), Magnetic iron oxide is a mixed oxide because when it reacts with conc. acids, two types of salts are produced.
Extraction of iron or its metallurgy is the process of obtaining this metal in a form where it can be put to practical use, and this process of extraction consists of three stages: Ore dressing, Reduction of ores and Iron production.
The aim of ore dressing is increasing the concentration of iron in the ore by removing the unwanted impurities and improve the properties of the ore which helps in the successive stages of extraction, The ore dressing process is carried out to improve the physical and mechanical properties of iron ore and includes Crushing process, Sintering process, Purification and concentration of the ore.
Crushing process is used to obtain iron ore in small size that can be reduced easily, Sintering process is used to obtain the fine particles of iron ores in large size, As a result of the crushing process & cleaning furnace a huge amount of fine particles of ore are obtained which can not be used directly in high furnace directly, these particles must be treated to collect them in a larger size to be similar & homogeneous and this process is called sintering.
The sintering process is the process of treatment of the fine particles of iron ore obtained from crushing process or in cleaning furnace to collect them in a larger size to be similar and homogeneous particles fit for reduction process.
Purification & concentration process is the process of using surface tension properly, magnetic or electrical separation to remove the unwanted impurities which are chemically combined or mixed with ore to increase the percentage of iron in the ore.
Ore-dressing process is also carried out to improve the chemical properties of ores by roasting, It means heating the substance strongly in the air for drying the ore, expelling humidity, converting the iron ore into oxide, increasing the ratio of iron in the ore, oxidation of some harmful impurities as (S and P).
Roasting is the process of heating iron ore strongly in dry air for drying the ore and expelling humidity, It is used to increase the percentage of iron in the ore and for the oxidation of some impurities such as sulphur and phosphorus.
Roasting of iron is very important in the ore dressing process but this process pollutes the environment, Ore dressing is important for iron ores before their reduction to remove most impurities and improve the physical & chemical properties of the ore.
It is very important to dress iron ores before reduction as the iron ore dressing improves physical, mechanical and chemical properties of the ores and makes it suitable to be reduced easily and effectively, The disappearance of the luster of a piece of iron when it is heated because the iron has the tendency to form a layer of iron oxide on its surface after heating.
The reduction process is the process of reducing iron oxides to iron by carbon monoxide resulting from coke in the blast furnace or by a mixture of carbon monoxide and hydrogen gases (water gas) resulting from natural gas in the Midrex furnace.
Reduction of Fe2O3 by using a mixture of carbon monoxide and hydrogen (water gas) that is produced from natural gas (93% methane) in the Midrex furnace to produce Spongy iron, Spongy iron is the iron mixed with impurities where it is produced from the midrex furnace and it has holes similar to that in the sponge.
After the reduction of iron ores in the blast furnace or Midrex furnace, the third step in which the production of different types of iron such as cast iron and steel, The steel industry depends on two essential processes:
Tags: Blast furnaceCast ironCokeConcentration of the oreCrushing processElectric FurnaceelementsExtraction of IronExtraction of Iron from its oresHeavy industriesHematiteImpuritiesIronIron configurationIron dressingIron importanceIron ore dressingIron oresIron oxidesIron percentageIron productionIron reductionLimoniteMagnetic iron oxideMagnetiteMeteoritesMethaneMidrex furnaceOpen-hearth furnaceOre dressingOxygen convertersPurificationReducing agentReduction of iron oresReduction of oresRoastingSideriteSintering processSpongy IronsteelSteel industry
The FIOR process was developed in the 1960s; the only commercial plant started up in Venezuela in 1976 and operated until 2000 [50,59]; the plant is still in existence, but is currently idle . It was designed with four fluid-bed reactors with gravity feed between them, a reformer, and a briquetter to compact the reduced ore. Preheated ore from the first reactor overflows to the second reactor; 10% of the reduction occurs there, with the remainder in the final two reactors .
The primary aim of the FINMET development was to improve the energy efficiency of FIOR by ore preheating using top gas and CO2 removal from reformed gas as well as recycle gas. Laboratory and pilot testing was conducted in 19931995, and plants in Australia and Venezuela were under construction in 1999 [52,63]. The Australian plant operated for several years, but shut down in 2005 due to operating issues. The Venezuelan plant is still in service, and is based on the flow sheet shown in Figure 1.2.15 . FINMET has four reactors, as well as a fluid-bed dryer. Solids temperatures increase as they move through the reactors; at the end temperatures may be as high as 800C and pressures up to 14bar gauge. The reducing gas is a combination of recycled process gas and fresh natural gas reformed using steam.
Hydrogen can serve as a reducing agent and the most prominent application appears to to be iron ore reduction. A variety of direct reduction of iron ores without coke has been carefully studied for a long time. These use hydrogen, carbon-monoxide and carbon in a combination. The reason for the development is due to the following:
A wide range of fuels including natural gas can be used. The historical usage of fuel for metallugical process has started from carbon, coal, which would change to mixture gas of CO, H2 and C. The merit is mostly to avoid the use of high grade coal and coke, and to avoid some of the attendant environmental problems.
An hydrogen-nitrogen reducing atmosphere (NH) is often used to prevent oxidation in annealing process of ferrous metals. This atmosphere can be used not only for annealing and heat treatment of nonferrous metals but is also used for the refining process to recover non-ferrous metals such as tungsten, molybdenum and magnesium. A reducing atmosphere of pure hydrogen is used in tungsten processing when oxide compacts are sintered. The molybdenum trioxide is reduced in a furnace with hydrogen at about 1, 000C to produce metal powder. This powder is formed into a sintered rod in a hydrogen atmosphere. Magnesium chloride can be electrolyzed or magnesium oxide can be thermally reduced. In both cases hydrogen gas is consumed.
The hot potassium carbonate process has been used effectively in many ammonia, natural gas, hydrogen, direct iron ore reduction, and ethylene oxide plants for many decades (Chapel etal., 1999). German patents using hot carbonate absorption of CO2 can be found from as early as 1904 (Kohl and Riesenfeld, 1985). In the 1950s, Benson and Field developed the BenField process which used hot carbonate solutions as the absorption liquid. The pressure swing between absorption and desorption was believed to be sufficient for CO2 regeneration without the requirement of an accompanying temperature swing (Benson etal., 1954). This enabled both absorption and regeneration to occur at the same elevated temperature, increasing the absorption kinetics (Kohl and Riesenfeld, 1985; Benson etal., 1956) and reducing the energy loads by almost half (Benson etal., 1956).
The most widely used commercial hot potassium carbonate process was licensed by Universal Oil Products (UOP) and is known as the UOP Benfield Process (Stanislav Milidovich and Zbacnik, 2013). Corrosion inhibitors and activators (or rate promoters) have been added to the original system to prevent corrosion and improve mass transfer efficiency. There are more than 700UOP Benfield process units in operation worldwide (see Fig.7.1 for a process flow diagram of the UOP Benfield process). A number of process variations have since been developed by UOP. The UOP Benfield ACT-1 activator process uses an activator to increase the mass transfer rates of CO2 absorption using hot potassium carbonate solutions. The UOP Benfield LoHeat Technology process is a near-isothermal Benfield unit operation that uses a flash drum with a range of configurations to progressively increase energy savings at the expense of capital cost increases. Finally, the UOP proprietary packing process uses hot potassium carbonate with tower internals from Raschig that have been designed to allow higher feed gas rates and therefore provide higher throughputs.
Eickmeyer and Associates, Inc. have been designing and implementing CATACARB enhanced Hot Potassium Carbonate (HPC) systems for ammonia and hydrogen plant applications since the early 1960s. A.G. Eickmeyer developed the original CATACARB process after realizing the advantages of the HPC process such as substantially lower regeneration heat requirement than amine processes, but absorption rates were slow leading to large equipment. Additionally, the solution was sometimes corrosive. Through the development of catalysts that increase the rate of absorption/desorption of acid gases and the use of corrosion inhibitors, costs were reduced by reducing equipment sizes, utility requirements, and minimizing the use of stainless steel. The CATACARB process has been designed for over 150 plants in over 30 countries for a wide range of applications with the most common being ammonia, hydrogen, natural gas, and ethylene oxide plants (Catacarb Eickmeyer & Associates, 2016).
Other commercial processes utilizing potassium carbonate solutions for acid gas removal include the ExxonMobil FLEXSORB SE technology which uses a hindered amine activator primarily for selective H2S removal (ExxonMobil Gas Treating, 2016) and the GiammarcoVetrocoke activated Hot Potassium Carbonate process which uses an organic promoter for CO2 absorption from a range of gas streams (GiammarcoVetrocoke, 2016). Most of these commercial processes were developed for CO2 removal from a high-pressure feed stream (often with a feed CO2 partial pressure of at least 700kPa). However, research that is more recent has demonstrated the use of hot potassium carbonate solutions for CO2 removal from post-combustion flue gases. Further information on these processes can be found in Section 7.6, dealing with pre-combustion applications.
Metallurgical coke is produced in coke ovens and is mainly used for the iron ore reduction in blast furnaces (BFs). It is also consumed in blast and electric furnaces for ferroalloy production and for the reduction of other metal oxides, chlorides, phosphates, sulfates, as well as for the reduction of carbonates to carbides.
The predominant amount of coke produced worldwide is metallurgical coke; the rest is mainly foundry coke, and the balance is made by domestic coke as well as by coke used in further industries, e.g., in sugar or mineral wool production. The global annual production of metallurgical coke ranged in the last years between 650 and 685Mt (dry basis); more information is given in Fig.13.1. World capacity of foundry coke is estimated at 2% of total coke capacity (US-ITC, 2000).
The main share of metallurgical coke is consumed in the steel industry to produce hot metal, which, in turn, is used as the main ingredient to make steel (Babich etal., 2016). Nut and breeze cokes as undersieve products of metallurgical coke are also widely used in the steel industry and, namely, in the BF and sintering processes, respectively (see Section 13.4.1). With respect to foundry coke, its use in iron cupola furnaces is discussed in Section 13.7.
Iron and steel metallurgy is the branch of pyrometallurgy (recovery of metals by the thermal treatment of minerals, ores, and concentrates) that deals with processes and technologies of production of iron and its alloys. It comprises ironmaking, steelmaking, secondary metallurgy, solidification, and casting. An integrated steelworks also comprise raw material preparation (typically, sinter and coking plants) and rolling mill (cold or/and hot ones); see Fig.13.2.
Figure13.2. Flow sheet of an integrated steel plant: 1, area of raw material delivery and handling; 2, sinter plant (agglomeration of fine iron ore); 3, coking plant (coke making from coal); 4, blast furnace (hot metal production by ore reduction); 5, hot metal desulfurization; 6, converter (transformation of hot metal in steel); 7, electric arc furnace (melting of steel scrap or sponge iron to steel); 8, secondary or ladle metallurgy; 9, continuous casting (transformation of liquid to solid steel); 10, hot rolling.
BFconverter (BOFbasic oxygen furnace). Hot metal is produced in the blast furnace (BF), which is then refined in the BOF to produce liquid crude steel (see area of Route 1 within dotted line in Fig.13.2).
World crude steel production reached 1630Mt in 2016 (Worldsteel, 2017) and steel use is projected to increase by 1.5 times by 2050 (Worldsteel, 2016). The major part of metallic charge for steel production is hot metal from BF (64.2%); steel scrap makes up 31.5%; a share of direct reduced iron and hot briquetted iron (DRI/HBI) and hot metal from SR makes up worldwide 4.0% and 0.3%, respectively (all the data from the year 2015 according to Lngen, 2017).
The steel industry is an energy-intensive branch. The energy efficiency depends mainly on production route (see above), type and quality of iron carriers and reductants, the steel product mix, and operation control technology. Energy is also consumed indirectly for the mining, preparation, and transportation of raw materials (about 8% of the total energy required) (Worldsteel, 2016). Specific energy consumption decreased tremendously in the last decades due to numerous technological and organizational measures. Thus, primary energy consumption in German steel mills decreased from nearly 30GJ per tonne of crude steel in 1960 down to 17.86GJ/t in 2015 (Stahl, 2016). Nevertheless, the steel industry is responsible for about 5%6% of worldwide energy consumption. About 50% of an integrated facility's energy input comes from coal, 35% from electricity, 5% from natural gas, and 5% from other gases (Worldsteel, 2016). The BF ironmaking including sintering and coking plants is the most energy consuming process at an integrated steel plant. It consumes about 65%75% of the entire energy in integrated steelworks (Babich etal., 2016). The main part of the required energy is covered by metallurgical coke.
Process flow sheets for the commercial-scale novel suspension ironmaking process based on purchased hydrogen were constructed and simulated. The proposed process was modeled in two configurations: 1-step and 2-step processes in which the number of iron ore reduction reactor is different. Simulation was performed under various operating conditions to examine the effect of operating conditions on the fresh hydrogen amount which would affect the economic feasibility greatly due to expensive hydrogen price.
Simulation results indicated that the 2-step process would use less fresh hydrogen than the 1-step process at the same operating condition. This is because the 2-step process requires less fuel than the 1-step process as the water vapor generated by combustion in the ironmaking reactor is smaller, which decreases hydrogen required to satisfy the specified excess driving force. Results also indicated that the increase in excess driving force would increase hydrogen consumption, especially at high excess driving force.
The energy balance comparison for the standard case (the ironmaking reactor temperature=1500C, excess driving force=0.5) indicated that the 1-step and 2-step processes would not have a significant difference in the energy requirement due to the difference in the ability to recover sensible heat in the off-gas. Energy requirement for the standard case operation compared with that of the average BF process, assuming that hydrogen and coking coal were the starting raw materials, indicated that the proposed process would require 57% and 60% less energy, respectively, for the 1-step and 2-step processes. The sensitivity analysis of the energy requirement to operating conditions indicated that the proposed process would still reduce energy consumption greatly compared with the BF process. However, it is noted that the energy for hydrogen or coal production must be added for a comprehensive comparison of the energy requirement, and it will depend on which materials are considered as the starting raw materials.
COURSE 50 project was proposed by IISI with six major steel industries and related company in Japan. COURSE 50 stands for CO2 Ultimate Reduction in Steelmaking Process by Innovative Technology for Cool Earth 50. Basic idea of COURSE 50 is the use of hydrogen for iron ore reduction and development of cheap hydrogen production technology, as well as CO2 separation and recovery . COURSE 50 program consists of two major research activities .
Development of technology to reduce CO2 emissions from blast furnaces, involvingdevelopment of reaction control technology to reduce iron ore by using hydrogen,reforming technology of COG that increases the amount of hydrogen produced, andtechnology to manufacture high-strength and high-reactivity coke for hydrogen reduction blast furnaces.
Development of technology to separate and recover CO2, involved with development of a high-efficiency CO2 absorption method and technology to utilize unused waste heat in steelmaking plants for CO2 separation and recovery.
Forecasts for long-term use of coal in the steel industry are extremely difficult because the combination of several uncertain factors, such as growth of population, development and use of new/alternative materials and energy sources, development of existing and new metallurgical technologies and, last but not least, political and social changes, will strongly affect the picture of the future.
Growth in demand for steel from about 1.4 billion tons in 2011 to 2.32.7 billion tons by 2050 is expected.11 The ratio of oxygen/electric steel (it means BF-BOF and scrap-EAF routes, see chapter 12) is assumed to switch from 70:30 today to 40:60% in 2050.12 That would mean that the oxygen steel production mainly using blast furnace iron-making remains more or less at the same level. The amount and structure/types of energy and reducing agents for iron ore reduction are key factors that will shape the future of the steel industry. The dominant energy inputs in an integrated steelworks today are coal/coke and some heavy oil, natural gas and other hydrocarbons.
A current modern steelworks is a highly optimised system in terms of consumption of energy and reducing agents. The blast furnace operates 5% away from the thermodynamics limit and the whole mill has a potential of energy savings of only about 10%.13 Energy consumption of best performing integrated steel works (BF-BOF route) makes up 17 GJ/t crude steel, 16 GJ/t of which is related to coal and 0.9 GJ/t to electricity. In a scrap-EAF route, the best results correspond to 3.5 GJ/t of hot rolled product, of which 1.6 GJ/t is related to electricity consumption, 0.6 GJ/t of fossil energy (coal and natural gas) and 0.3 GJ/t of energy for hot rolling and 1 GJ/t natural gas for the reheating furnace.14 At the same time, the worst performers are at the level of 50 and 30 GJ/t crude steel for the BF-BOF and the EAF routes respectively.7 Improvement of performance of all the other steelworks to the level of the current best performing ones offers an enormous potential for energy saving.
Environmental challenges facing the steel industry require very large cuts in CO2 emissions; even todays best metallurgical technologies are not clean enough and radical improvement will be required to meet emerging mandatory targets. CCS as a tool for mitigation CO2 emissions in the steel industry could be deployed in the future for existing and new iron-making processes, if still open, technical, economic and social problems related to the CCS will be solved.
Another way to reduce the CO2 emissions is related to a change in the structure of energy sources. Coal used for iron ore reduction can be replaced by hydrogen, electricity or biomass. Industrial implementation of these energy sources depends on their sustainability, availability and costs, i.e. sustainable plantations, processing and use of biomass, avoiding conflicts between energetic use of biomass and food security, use of CO2-lean electricity, development of technically and cost-acceptable methods of electrolysis, etc. On the other hand, new iron-making technologies still have to be developed; existing ones enable only partial replacement of coal/coke by the above-mentioned sources.
Looking at the existing coke, iron and steel making technologies, further increase in carbon use efficiency and cost optimisation is needed. It is commonly recognised that until now, coke quality produced from coking coals with well-defined properties has been a prerequisite for high efficiency blast furnace operation. An increasing demand on coke (nearly 600 Mt of coke on dry basis was produced in 2010) and depletion of resources of high quality coals leads to frequently changing coal blends and drives up the price.
The strategy on coke quality should be shifted from maximising to optimising its properties. Optimum quality in general means coke that is adequate for needs considering both costs and availability. Furthermore, blast furnace operation with low coke rate, high PCI rate (>250kg/THM) and other injectants causes a change in coke quality requirements; some of its functions become less important (heat source, reducing agent), other tasks (maintenance of gas permeability) become decisive. Solution loss reaction, alkali and high temperature attack influence the coke degradation behaviour strongly.15
Standard characteristics of coke quality and test methods are therefore not sufficient to simulate real conditions in a modern blast furnace. They provide limited assessment of coke properties under limited reacting conditions and should be complemented with new ones.
Iron ore carbon agglomerates (self-reducing pellets, briquettes or composites) with embedded coal or other carbonaceous materials might be used in the blast furnace for decreasing the carbon consumption and in direct reduction processes for improving their performance and productivity.
Use of a broader palette of coals and cokes enables the further reduction of costs. Examples include the efficient use of nut coke and anthracite in the blast furnace, the briquetting and hence use of fine coals for injection in Corex/Finex smelting reduction technologies.
The research on the reduction of iron ore has received much attention in the past few decades as a result of the increasing cost and low availability of raw materials. The reduction of gaseous emissions and the search for low-cost alternatives to traditional routes has also boosted the investigations for reduction processes (Plaul et al., 2009).
Currently the dominating process for the iron-ore reduction is the blast furnace (BF) technology. These furnaces consist of a moving bed reactor with a counter-current flow of the solid reactants against a reducing gas. Not only are the energy costs relatively high for these blast furnaces the pollution problems can also be quite severe. The iron-ore fines that enter the BF need to go through a pelletizing and sintering process. In other cases, such as the smelting reduction (SR) processes that use the fluidized bed technologies the iron-ore fines can directly be charged into the reduction process making it highly advantageous. Such fluidized bed reactors are used in the pre-reduction stage of the FINEX process (Habermann et al., 2000). The FINEX process, which was jointly developed by POSCO (Korea) and Primetals Technologies (Austria), produces hot metal in the same quality as traditional blast furnaces. The iron-ores that are charged into the process go through fluidized bed reactors where they are heated and reduced to Direct Reduced Iron (DRI). The DRI is then charged into the melter gasifier where the final reduction and melting as well as the production of reducing gas by gasification of coal with oxygen takes place (Schenk, 2011).
To improve these processes computational tools such as the CFD-DEM method, which uses the coupling of CFD for the continuous fluid phase (i.e. the reduction gas) and DEM for the discrete particles such as iron-ore and coal, can bu utilized. In this work, we are using the CFD-DEM coupling approach based on the open source software packages OpenFOAM and LIGGGHTS (Goniva et al., 2012). The Eulerian field follows a continuum approach and volume-averaged continuity equations are used to describe the behavior of the flow. The discrete particles are described by Newtons equations of motion. More information about the CFD-DEM system can be found in the works of Zhou et al. (2010). In this case, the DEM provides an easy way to evaluate the per-particle chemistry such as the shrink/growth of particles due to reactions. Other tools such as the Two-Fluid Model (TFM), can also be used. However, this model lacks the proper representation of particle size description and the related physical phenomena. Another method that can be thought of would be the hybrid Lagrangian-Eulerian model that combines the Lagrangian Discrete Phase Model (DPM) and a coarse-grained TFM such as in the works of Schneiderbauer et al. (2016).
A very high temperature gas-cooled reactor (VHTR) is an inherently safe reactor that can produce heat of 750C950C. By virtue of its high temperature heat, a VHTR can be used in high-temperature process heat applications, including hydrogen production and high-efficiency electricity generation. The most effective application of a VHTR is the massive hydrogen production in support of the hydrogen economy.
The rapid climate changes and heavy energy reliance on imported fossil fuels have motivated the Korean government to set up a long-term vision for transition to the hydrogen economy in 2005. One of the big challenges is how to produce massive hydrogen in a clean, safe, and economic way. Among the various hydrogen production methods, massive, safe and economic production of hydrogen by water splitting using a VHTR can provide a successful path to the hydrogen economy. Particularly in Korea, where the use of land is limited, the nuclear hydrogen is deemed a practical solution, due to its high energy density.
Another merit of the nuclear hydrogen is that it is a sustainable and technology-led energy unaffected by the unrest of fossil fuel. Current hydrogen demand is mainly from oil refinery and chemical industries. Hydrogen is mostly produced by steam reforming using fossil fuel heat, which emits a large amount of greenhouse gases. Today in Korea, more than 1Mtons/year of hydrogen is produced and consumed in oil refinery industries. In 2040, it was projected on a hydrogen roadmap that 25% of the total hydrogen demand will be supplied by the nuclear hydrogen, which is around 3Mtons/year, even without considering the hydrogen iron ore reduction.
In order to prepare for the upcoming hydrogen economy, the nuclear hydrogen key technologies development project was launched at KAERI in 2006 as a national program of the Ministry of Education, Science and Technology (Chang etal., 2007). KAERI has taken a leading role in the project and the development of VHTR technologies. The Korea Institute of Energy Research (KIER) and the Korea Institute of Science and Technology (KIST) are leading the development of the SI (sulfuriodine) thermochemical hydrogen production technology. The KAEC officially approved the nuclear hydrogen program in 2008, the amendment of which was made in 2011. The final goal of the program is to demonstrate and commercialize the nuclear hydrogen by 2030.
The nuclear hydrogen program consists of two major projects: the nuclear hydrogen key technologies development project and the NHDD project. Fig.13.2 illustrates the plan of the nuclear hydrogen program.
The key technologies development project focuses on the development and validation of key and challenging technologies required for the realization of the nuclear hydrogen system. The key technologies selected are the design codes, high-temperature helium experiment, high-temperature material database, TRISO fuel, and thermochemical hydrogen production. This project has been carried out in phase with both the NHDD project and the GIF projects, and will continue until 2016.
The NHDD project is aimed at the design and construction of a nuclear hydrogen demonstration system for demonstration of massive hydrogen production and system safety. A VHTR systems concept study has been performed for 3years since 2011. The main objectives of this study are to develop the VHTR systems concept for nuclearprocess heat and electricity supply to industrial complexes, for the massive nuclear hydrogen production required to enter into a future clean hydrogen economy, and to establish the demonstration project plan of VHTR systems for subsequent commercialization.
As part of the VHTR system concept study, (1) the plant design and functional requirements for both commercial-scale nuclear process heat and nuclear hydrogen systems are developed; (2) the design concepts, layout, and operating parameters of reactor and plant systems are optimized; (3) the design concepts of key high-temperature components and materials are investigated and assessed for manufacturing and procurement purposes; and (4) the design concepts of underground reactor building, radioactive waste management, and radiation protection are evaluated. In parallel, the design analysis systems of reactor and plant systems are constructed and applied for a performance analysis, and the system concept of a demonstration plant is developed and suggested.
As part of the demonstration project plan, commercial-scale plant concepts of both nuclear process heat and nuclear hydrogen systems were first selected reflecting the market needs and opinions of potential customers and vendors, and an economic feasibility study was carried out. Based on the above, the project structure and strategy of the demonstration project and subsequent commercialization project were established together with the relevant business model.
The project plan includes not only the project structure, schedule, budget, and project strategies to secure project financing, government support, site, and licensing, but also the technology development and validation plan required in the process of licensing of the demonstration plant. A stepwise demonstration using a single reactor system was adopted to reduce the technology and business risks, as shown in Fig.13.3. The reactor technology is demonstrated first at the core outlet temperature of 750C based on mature technologies. The demonstration of reactor technology will be finished in 10years. The hydrogen production technology will be developed through international collaboration in parallel with the basic and detailed design of the reactor technology demonstration. The construction of a hydrogen production system will be finished before the demonstration of the reactor technology, which will be followed by the reactor system modification and integration. After that, the demonstration of nuclear hydrogen production will be completed in 2years.
According to the government suggestion, VHTR systems point design started in 2015 instead of the conceptual design of the demonstration plant. The purpose of the point design is to generate design data of the stepwise and integrated demonstration plant. The data will be used not only for the conceptual design, but also for a feasibility assessment of the demonstration project. KAERI will apply for prefeasibility approval to the government based on the point design results to be given support from the government. Regardless of launching the demonstration project, the GIF studies will continue because the Korean government signed an extension of the GIF framework agreement for another 10years until 2026.
Answer true or false:1.Design of a system implies specification of the design variable values.2.All design problems have only linear inequality constraints.3.All design variables should be independent of each other as far as possible.4.If there is an equality constraint in the design problem, the optimum solution must satisfy it.5.Each optimization problem must have certain parameters called the design variables.6.A feasible design may violate equality constraints.7.A feasible design may violate type constraints.8.A type constraint expressed in the standard form is active at a design point if it has zero value there.9.The constraint set for a design problem consists of all feasible points.10.The number of independent equality constraints can be larger than the number of design variables for the problem.11.The number of type constraints must be less than the number of design variables for a valid problem formulation.12.The feasible region for an equality constraint is a subset of that for the same constraint expressed as an inequality.13.Maximization of f(x) is equivalent to minimization of 1/f(x).14.A lower minimum value for the cost function is obtained if more constraints are added to the problem formulation.15.Let fn be the minimum value for the cost function with n design variables for a problem. If the number of design variables for the same problem is increased to, say, m = 2n, then fm > fn, where fm is the minimum value for the cost function with m design variables.
Let fn be the minimum value for the cost function with n design variables for a problem. If the number of design variables for the same problem is increased to, say, m = 2n, then fm > fn, where fm is the minimum value for the cost function with m design variables.
A trucking company wants to purchase several new trucks. It has $2 million to spend. The investment should yield a maximum of trucking capacity for each day in tons kilometers. Data for the three available truck models are given in Table E2.20: truck load capacity, average speed, crew required per shift, hours of operation for three shifts, and cost of each truck. There are some limitations on the operations that need to be considered. The labor market is such that the company can hire at most 150 truck drivers. Garage and maintenance facilities can handle at the most 25 trucks. How many trucks of each type should the company purchase? Formulate the design optimization problem.
A large steel corporation has two iron-ore-reduction plants. Each plant processes iron ore into two different ingot stocks, which are shipped to any of three fabricating plants where they are made into either of two finished products. In total, there are two reduction plants, two ingot stocks, three fabricating plants, and two finished products. For the upcoming season, the company wants to minimize total tonnage of iron ore processed in its reduction plants, subject to production and demand constraints. Formulate the design optimization problem and transcribe it into the standard model.Nomenclature (values for the constants are given in Table E2.21)Table E2.21. Constants for Iron Ore Processing Operationa(1,1) = 0.39c(1) = 1,200,000k(1) = 190,000D(1) = 330,000a(1,2) = 0.46c(2) = 1,000,000k(2) = 240,000D(2) = 125,000a(2,1) = 0.44k(3) = 290,000a(2,2) = 0.48b(1,1,1) = 0.79b(1,1,2) = 0.84b(2,1,1) = 0.68b(2,1,2) = 0.81b(1,2,1) = 0.73b(1,2,2) = 0.85b(2,2,1) = 0.67b(2,2,2) = 0.77b(1,3,1) = 0.74b(1,3,2) = 0.72b(2,3,1) = 0.62b(2,3,2) = 0.78a(r, s) = tonnage yield of ingot stock s from 1 ton of iron ore processed at reduction plant rb(s, f, p) = total yield from 1 ton of ingot stock s shipped to fabricating plant f and manufactured into product pc(r) = ore-processing capacity in tonnage at reduction plant rk(f) = capacity of fabricating plant f in tonnage for all stocksD(p) = tonnage demand requirement for product p
Production and demand constraints:1.The total tonnage of iron ore processed by both reduction plants must equal the total tonnage processed into ingot stocks for shipment to the fabricating plants.2.The total tonnage of iron ore processed by each reduction plant cannot exceed its capacity.3.The total tonnage of ingot stock manufactured into products at each fabricating plant must equal the tonnage of ingot stock shipped to it by the reduction plants.4.The total tonnage of ingot stock manufactured into products at each fabricating plant cannot exceed the plants available capacity.5.The total tonnage of each product must equal its demand.
Optimization of a water canal. Design a water canal having a cross-sectional area of 150m2. The lowest construction costs occur when the volume of the excavated material equals the amount of material required for the dykes, that is, A1=A2 (see Fig. E2.22). Formulate the problem to minimize the dugout material A1. Transcribe the problem into the standard design optimization model.
A cantilever beam is subjected to the point load P (kN), as shown in Fig. E2.23. The maximum bending moment in the beam is PL (kNm) and the maximum shear is P(kN). Formulate the minimum-mass design problem using a hollow circular cross-section. The material should not fail under bending or shear stress. The maximum bending stress is calculated as(a)=PLIRowhere I = moment of inertia of the cross-section. The maximum shearing stress is calculated as(b)=P3I(R02+R0Ri+Ri2)
Transcribe the problem into the standard design optimization model (also use Ro 40.0 cm, Ri 40.0 cm). Use this data: P = 14 kN; L = 10 m; mass density = 7850 kg/m3; allowable bending stress b = 165 MPa; allowable shear stress a = 50 MPa.
Design a hollow circular beam-column, shown in Fig. E2.24, for two conditions: When the axial tensile load P = 50 (kN), the axial stress must not exceed an allowable value a, and when P = 0, deflection due to self-weight should satisfy the limit 0.001L. The limits for dimensions are: thickness t = 0.101.0 cm, mean radius R = 2.020.0 cm, and R/t 20 (AISC, 2011). Formulate the minimum-weight design problem and transcribe it into the standard form. Use the following data: deflection = 5wL4/384EI; w = self-weight force/length (N/m); a = 250 MPa; modulus of elasticity E = 210 GPa; mass density of beam material = 7800 kg/m3; axial stress under load P, = P/A; gravitational constant g = 9.80 m/s2; cross-sectional area A = 2Rt (m2); moment of inertia of beam cross-section I = R3t (m4). Use Newton (N) and millimeters (mm) as units in the formulation.
The possibility of using iron-ore enrichment tailings in the production of ceramic articles is investigated. The compositions and properties of ceramic bodies and the process parameters for manufacturing articles are presented. To increase product quality nepheline concentrate is used as an alkali-containing additive.
O. V. Suvorova, D. V. Makarov, and V. E. Pletneva, Ceramic materials based on tailings from enrichment of vermiculite and apatite nepheline ores, Steklo Keram., No. 7, 22 24 (2009); O. V. Suvorova, D. V. Makarov, and V. E. Pletneva, Ceramic materials based on tailings from enrichment of vermiculite and apatite nepheline ores, Glass Ceram., 66, No. 7 8, 255 257 (2009).
N. F. Shcherbina and T. V. Kochetkova, Use of nonferrous metal ore concentration wastes in production of ceramics, Steklo Keram., No. 10, 31 33 (2007); N. F. Shcherbina and T. V. Kochetkova, Use of nonferrous metal ore concentration wastes in production of ceramics, Glass Ceram., 64(9 10), 366 368 (2007).
The water absorption of the ceramic articles obtained is less than 18%. This corresponds to the requirements of the standard RST RSFSR 604.91 Ceramic Articles from National Art and Pottery Industries.
Shcherbina, N.F., Kochetkova, T.V. Use of Iron-Ore Enrichment Tailings in the Production of Ceramic Articles. Glass Ceram 73, 2224 (2016). https://doi.org/10.1007/s10717-016-9818-7
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Probably due to large national land area and multi-period orogeny, from the view of metallogeny, lots of iron deposits developed in China, and the proven total reserves of iron ores are relatively abundant, but mainly low-grade ores. For years, Chinas iron ore reserves are far from being able to meet the requirement of rapid development of steel industry. China is the worlds largest importer of iron ore, whose imports accounted for one-third of the worlds total in recent decades; however, the buyer has not the final say. The strategic importance of iron ore resources in national economy not only depends on the social value and economic value created by the iron ore exploitation, but also depends on whether the requirements of the steel industry and steel downstream industry, and safety ensuring, economy and sustainability of steel and steel downstream industry. Herein, the iron mineral processing and metallurgy technology are also briefly illustrated.
This chapter will give a general description on the Chinese iron ore deposits, supply and demand market, mineral processing and iron ore metallurgy technology. For years, the Chinese iron industry is highly dependent on the foreign mines due its quick development on economics. Presently, it is the worlds largest importer of iron ore, whose imports accounted for one-third of the worlds total. In fact, it holds abundant iron resource, although most are low grade and small. Therefore, the mineral processing and metallurgy technology quickly develop accompanying its iron demand and economic soaring.
Probably due to large national land area and multi-period orogeny, lots of iron deposits developed in China, and the proven total reserves of iron ores are relatively abundant, but mainly low-grade ores. The research shows that the types of iron ore deposits in China are diverse and the metallogenic epoch spanned from the Archean to the Cenozoic, which mainly includes seven types [1, 2, 3, 4, 5, 6].
This type of iron deposits is also called banded iron formation (BIF). The mineralization ages were mainly Archean and Paleoproterozoic. The reserves of proven mineral resources were probably more than 33 billion tons, accounting for 55% of the total reserves of the country, which is a very important iron ore in China. According to the ore and gouge mineral association, as well as geological features, it would be subdivided into metamorphic iron-siliceous iron ore deposits and metamorphic carbonate iron ore deposits. Their grades were about 2540% (w(TFe)).
The BIF were affected by regional metamorphism and associated with volcanic-iron-siliceous sedimentary deposits. They mainly developed in the Precambrian metamorphic rocks, mostly large deposits. The Anshan in Liaoning Province, Jidong in Hebei Province, Wutai-Lvliang in Shanxi Province, and central Inner Mongolia are mainly developed area where the iron ore deposits were thought the most representative. The southern margin of Yangtze plate, Qinling orogenic belt, Qilian orogenic belt, and the East Tianshan region were also distributed.
The metamorphic carbonate iron deposits were carbonate-type sedimentary iron deposits suffered to minor regional metamorphism. They mainly developed in the Proterozoic strata, and the southeast Jilin Province is known for yielding this deposit. That led to it also called Dalizi type iron ore deposit in China, although it is also developed in Yimen, Eshan, Huanian in Yunnan Province.
This type of iron ore deposit is associated with the mafic-ultramafic magmatic intrusions of the iron and its iron minerals are rich in vanadium and titanium, commonly referred to as vanadium-titanium magnetite deposits. The mineralization ages are mainly Paleozoic and Proterozoic, with proven reserves of 9 billion tons, accounting for 15% of the total reserves of the country. According to the metallogensis, they can be subdivided into late magmatic differentiated deposits and late magmatic intrusive iron deposits. Late magmatic differentiated iron deposits are formed by the residual magma rich in iron, vanadium and titanium formed by late differentiation of magma crystals. These deposits are mostly of large in reserve and are mainly distributed in Panzhihua and Xichang area in Sichuan Province. They are often called Panzhihua-type iron deposits in China. Late magmatic intrusive iron deposits are late-differentiated iron-bearing ore fluids that break into or along the rock mass. The reserve of this type deposit is generally medium to small, mainly distributed in the Damiao and Heishan in Hebei Province, which is called the Damiao-type iron deposit.
This type of iron ores are associated with the contact metasomatism resulted from intrusive rocks and carbonate rocks, and are formed by the exchange of iron-bearing gas-water solutions. Such deposits generally have typical skarn mineral assemblages and are also known as silicon carbon type deposit. Skarn iron ore ages were mainly Mesozoic, ore grade is generally rich, the reserves are generally small and medium, although there are some large ones. Identified reserves of this type are 8 billion tons, accounting for 13% of the total reserves. Skarn iron ore is widely distributed in China, with such deposits as Handan, Laiwu, Daye and Linfen in the east. In addition, Cuihongshan in Heilongjiang Province, Huanggang in Inner Mongolia, Lizhu in Zhejiang Province, Dading in Guangdong Province, Mulonggou in Xianxi Province and Nixon in Tibet also yield skarn type iron ore deposits.
This type of deposit is associated with volcanic rocks and sub-volcanic rocks in a genetic relationship, with a proven reserve of 2 billion tons, accounting for 4% of the countrys total reserves. It would be divided into continental volcano-intrusive iron ore and marine volcano-intrusive iron deposits.
Continental volcanic-intrusive iron ore deposits are mostly associated with middle- or medium-acid volcanic rocks and are mainly produced in volcanic clasts or in the contact zones within and around the pluton. The mineralization age is Mesozoic. It is mainly located in Ningwu-Luzong area, often referred to as porphyrite iron ore. In addition, the Jiaduoling iron ore deposit in Tibet and the Liangzi iron ore in Sichuan Province are also known as continental volcano-intrusive iron deposits.
This type of deposits was formed by weathering, then broken, decomposed, transported of iron-bearing rock to low-lying basins, and after mechanical deposition, or some through the deposition of differentiation. Metallogenic times of sedimentary iron deposits are diverse with a proven mineral resource of 5 billion tons, accounting for 9% of Chinas total reserves. According to the sedimentary environment, there are two subtypes of this kind: marine type and lake facies type. Marine sedimentary iron deposits were produced in various geologic periods after Neoproterozoic. It is represented by Xuanlong iron ore of Pangjiabao and the Ningxiang iron ore Ningxiang in Hebei Province.
These deposits are formed by weathering and leaching of the rich iron rocks and/or iron-bearing polymetallic ores, and iron ore was accumulated on the residual slope. This type is shallow and mainly of middle and small in reserve. They are mainly distributed in Guangdong, Guangxi, Fujian, Guizhou and Jiangxi Provinces. The reserves of proven deposits are 300 million tons, accounting for 0.5% of the total reserves of the country.
The Bayan Obo deposit is a world famous super-large iron-niobium-rare earth deposit with extremely rich minerals and elemental assemblages. However, due to the complexity of the iron deposit, there is no unified view on the origin of this deposit. Most believe that the formation and original deposition of iron ore associated with later hydrothermal fluid alteration, which means the iron ore was enriched by alteration on the primary ores. The mineral composition of the Bayan Obo mine is extremely complex. A total of 71 elements have been discovered and the mineral species have reached more than 170 species. There are five major ore bodies, with the iron deposits mainly occurring in the 8th member of the Bayan Obo Group. Proven reserves reach 1.6 billion tons [7, 8, 9, 10].
Shilu iron deposit in Hainan Province was hailed as Asias largest iron ore rich, and ore mineral is mainly hematite, associated with cobalt, copper and nickel. At present, there is no unified understanding of the ore-forming mechanism of Shilu iron ore deposit. Some argued that formation of Shilu iron ore is mainly due to multiple remodeling and enrichment that is, the formation of iron ore deposits is affected by volcano-sedimentary metamorphism + structural transformation + hydrothermal. A total of 38 iron ore bodies have been found, most of which are yielded in the 6th layer of Shilu Group. The proven iron ore reserve has exceeded 450 million tons and the grade is high (the average grade of iron ore is 51%) [11, 14, 15].
Iron ore resources are distributed in a few countries and regions with high concentration. 75.6% of the worlds iron ore reserves are distributed in Russia, Ukraine, Australia, Brazil, Kazakhstan and China. In general, there are more iron-rich mines in the southern hemisphere and less in the northern hemisphere . Among the top 100 iron ore production projects in the world , 76 are related to BIF and the output of these 76 BIF-related iron ore projects also accounts for 87% of the worlds iron ore production (Figure 1). The giant iron deposits in China are all BIF type and were yielded in craton. The largest one hosted about 4 billion tons of iron and was formed in Middle Archeozoic. However, it was low grade, whereas to the giant iron deposits abroad, they are various from skarn-related type, Kiruna type or magmatic type for the metallogeny. Besides, they are not restricted to Precambrian. For the tectonic background, they could develop on craton, as well as on active continental margin.
Among more than 2000 iron ore deposits identified, the contact metasomatic-hydrothermal iron deposits account for 39% of the total iron ore deposits, followed by sedimentary metamorphism (28%) and sedimentary (20%), weathered leaching (7%), volcanic (3%) and magmatic (3%) iron ore are in small numbers. However, most of the large iron deposits are characterized by sedimentary metamorphism type, accounting for 54% of the total number; followed by magmatic type, accounting for 17%; and the contact metasomatism-hydrothermal iron deposits are dominated by small and medium-sized, while the large ones accounting for only 13%; weathered leaching type do not yield large iron ore deposits (Figure 2).
Chinas iron ore sources are mainly three parts, the first part from the domestic ore, the second part from the overseas rights and interests of ore and the third part from overseas imports of ore. From 2011 to 2015, the proven reserves of iron ore continued to increase. In 2015, the reserves of iron ore reached 20.76 billion tons (note: different from the US Geological Survey released 2015 reserves data, it is mainly caused by different iron ore units of measurement), a slight increase of 0.50% year-on-year. Since 2015, Chinas iron ore production has gradually declined. In 2016, Chinas iron ore production (including low grades) was 1.281 billion tons, down 7.27% year-on-year.
As Chinas crude steel production for many years running high, and more than 90% of the output is made of iron ore as a raw material contribution, resulting in huge demand for iron ore. While importing a large amount of iron ore, the output of China made iron ore is rapidly growing. Before 2000, Chinas iron ore output has been stable at an annual of less than 200 million tons (Figure 3). The output has continued to increase rapidly since 2001, with an annual output of 590 million tons in 2006 and a record high growth rate of 38%. During 20072009, Chinas iron ore demand was strong and the supply of oversea deposits increased more rapidly. Although the total output amount of domestic mines continued to increase, its growth rate slightly decreased from the previous period. In 20102011, due to the 4 trillion yuan investment stimulating steel consumption in China and the rapid growth of international iron ore prices, historical records have been continuously refreshed. Many low-grade deposits, previously considered non-economic for mining, have also been gradually exploited. Domestic iron ore in 2011 reached 1.32 billion tons, an increase of 27%. After 2012, the growth of Chinas economy slowed significantly; however, the supply of oversea deposits continued to accelerate. Therefore the demand exceeds supply was gradually reversed. As a result, the price gradually dropped and the domestic high-cost mines were gradually squeezed out of the market. In 20122014, the growth rate of output of domestic iron ore decreased rapidly, and the output of in 2014 was 151,000 tons, an increase of 3.9%, although it slightly increased in 2016. In the past 16years, Chinas domestic iron ore production increased 7.4 times, an average annual growth rate of 14.6%, and domestic iron ore is an important part of Chinas steel production of raw materials.
Between 2003 and 2017, the average annual growth rate of Chinas iron ore output was about 18%. Meanwhile, the average annual growth rate of imported iron ore was 20%. The growth rate of imports was obviously higher than that of self-produced ore. Since 2000, Chinas iron ore imports, except a slight decrease in 2010, 2012 and 2015, increased substantially, the annual import grew twice over 35%.
By 2000, the major steel-making countries accounted for a relatively large amount of global imports. For example, Japan, the country with the largest import tonnage, accounted for an annual average of 28% in the world (Figure 4). Since 2000, due to the rise of China, the worlds iron ore import pattern has undergone dramatic changes. China surpassed Japan in 2003 to become the worlds largest importer of iron ore. The proportion of South Korea, Germany and Taiwan of China decreased slightly but little changed. The proportion of Japan was smaller; however, it is still the second largest iron ore importer in the world. In 2014, China imported 922 million tons of iron ore, accounting for 48% of the global output, 64.3% of the worlds total iron ore imports and more than 70% of the global iron ore seaborne volume, and contributing to more than 90% of global iron ore consumption. In 2017, Chinas iron ore imports increased to 1.075 billion tons, which is 14 times of 2000. China is the worlds most important iron ore consumer market and the worlds largest spot market for iron ore. At this stage of relatively stable demand in Japan, South Korea, Germany and Taiwan of China, the proportion of imports from other countries is too small and China imports huge amount of iron ore, the changes in the demand for imported iron ore in Chinas iron ore market can approximately reflect the changes in the global iron ore spot market.
Chinas iron ore resources development of going global has 30years of history. In 1987, Sinosteel Australia Limited and Australias Morris Iron Ore Co., Ltd. formed a contractual joint venture to jointly develop and operate Chana Iron Mine, making it the first overseas iron ore investment project. A total investment of 200 million US dollars, officially put into operation in 1990, iron ore production in 2011 reached 11 million tons. Due to the still low domestic demand at that time, the increase rate of overseas investment and mine development was relatively slow. In recent years, due to the sharp increase of iron ore demand, the scale of overseas investment in iron ore in China began to gradually expand [14, 15, 16]. From 2006 to 2017, the investment in the rights and interests of overseas iron mines of various types of enterprises totaled more than 30 billion dollars and participated in the exploration, design and construction of more than 40 large-scale overseas iron ore projects .
Chinas overseas investment in iron ore is mainly concentrated in Western Australia, Quebec of Canada, Brazil, Mongolia and West Africa (Figure 5). Among them, there are 19 cooperation projects in Australia with high grade and abundant resources of iron ore, accounting for almost half of all overseas projects . Canada mainly includes five projects of Wuhan Iron and Steel Group Company. There are three projects in West Africa, mainly in Guinea where invested 20 billion yuan, conducted by the Aluminum corporation of China. Due to differences in infrastructure investment, labor costs and resource conditions, the cost of projects invested in West Africa is lower than that in Australia. Up to 2013, Chinas overseas rights and interests iron ore production capacity of 73 million tons, accounting for about 10% of iron ore imports. However, compared with Japans overseas rights and interests iron ore production capacity of 74 million tons, accounting for 5770% of its annual import of iron ore, the gap between China and Japan is too large .
The global high-quality resources of iron ore have all been controlled by four enterprises. Oversea investment is high cost. As iron ore prices soared, Chinese enterprises have gone out to prospecting. When the spot price is as high as 130180 US dollars/ton, the average mining cost can be sufficient for 100 US dollars. Based on this, mining enterprises go out to buy the rights and interests of the cost of the current spot price are very high. According to public information, it is learned that in recent years, the minimum cost for China to go overseas to acquire iron ore right and interests is the iron ore project in Liberia of WISCO, accounting for about 70 US dollars/ton at that time. However, due to the drastic drop of iron ore prices since 2014, up to the beginning of November 2015, the domestic spot price of iron ore has dropped below 50 USD/ton. For the 2 years 20142015, the development cost of overseas rights and interests mines are almost totally higher than the spot price, and the volume of iron ore shipped back to the China will inevitably decrease drastically. The high cost of mining, coupled with the cost of repatriation, is completely unmanageable compared to the spot price of $5040/ton.
Due to the continuous high output of crude steel in China for many years and the fact that more than 90% of the output is contributed by iron ore (long-flow steel), the demand for iron ore is huge. The output of domestic iron ore increased rapidly, with a compound annual growth rate of about 14%. In terms of quantity, the output of domestic ore is much higher than that of imports. Although the growth of Chinas own-produced iron ore is rapid, it has been found in actual research that the actual growth of Chinas domestic iron ore production is much lower than the statistic data. In the statistics data on iron ore production, there is no distinction between finished ore and raw ore, the low grade of raw ore without treatment was put directly into the statistics data, resulting in a sharp rise in Chinas domestic iron ore output data. In recent years, due to soaring iron ore prices, low grade of 10% of the iron ore is exploited; at the same time, these low grade ore will inevitably push up China iron ore production data.
After iron balance rebound calculation, China made only 210 million tons of domestic finished iron ore in 2014. It is far from 1.5 billion tons which is from statistics data. The self-sufficiency rate of iron ore dropped from nearly 60% in 2002 to a nearly straight decline. The huge contrast between country-made ore and those data of the after iron balance rebound calculation means that the supply of domestic ore is approaching the end of its growth.
Although the total reserves of iron ore resources in China are huge, the distribution of iron ore resources is more dispersed, with more lean mines, very few rich mines, and mostly polymetallic iron mines. The ores are difficult to mine, the cost of mining is high, and the actual output cannot meet the production needs of domestic steel mills, therefore domestic steel producers have to choose to import large quantities of iron ore. Since 2000, Chinas iron ore imports have risen sharply, except a few years. The annual import growth rate once exceeded 40% twice.
With the rapid increase in iron ore imports, there is also a growing dependence on foreign iron ore (Figure 6). From only 36% in 2002, Chinas iron ore dependence on foreign countries has risen to more than 87% in 2016. In the coming years, the imported iron ore will remain at a high level. With the further price drop of imported iron ore, the domestic mines will be discontinued and the scope of bankruptcy will continue to expand. The import volume will continue to increase. The dependence on foreign iron ore will be over 90%.
Chinas imports of iron ore are mainly iron ore powder, massive iron ore (raw ore) and pellets, respectively, from more than 30 countries and regions, in which Australia, Brazil, India and South Africa are Chinas most important source of iron ore imports. The imports from the four countries accounted for about 85% (Figure 7). To protect its iron ore resources, the Indian government gives priority to ensuring its domestic steel production needs. Since 2011, the Indian government has increased export tariffs on iron ores and restricted exports. In recent years, the number of imported iron ore from India has been declining year by year. CVRD (Companhia Vale do Rio Doce in Brazil) is one of the main channels for Chinas iron ore imports, accounting for an average annual import volume of about 23%, but its proportion has dropped to 18% due to the substantial increase in the supply of iron ore from Australia in 2016 and 2017. South Africas imports were relatively small, accounting for about 6% of the total. Australia is the most important source of iron ore. The average annual import volume accounted for 44%. Due to economies of scale and the efficiency gains for mining companies, the mining cost was getting down. Rio Tinto said publicly in 2014 that the cost of mining had fallen to less than $18/ton. Therefore, Chinas total imported iron ore from Australia is likely to continue to increase.
China iron ore import country analysis (left axis account for Australia, India, Brazil South Africa of the total import volume, and right axis account for sum of the four places mentioned above for the total import volume of the whole China).
Now that iron ore is no longer a simple mean of production, its financial properties are gradually appearing. The major mines have been firmly controlled by financial capital (Figure 8). After understanding the global iron ore production costs, it is possible to speculate on the soaring of iron ore prices in previous years that the huge financial capital behind it is the most important promoter. At the present stage where the political situation is relatively stable, the main risk of over-concentration of import sources is the manipulation of iron ore prices stemming from the financial capital giants behind the mines. If the political situation in the future changes suddenly and the relevant governments at the source of imports restrict the export of iron ore to China, the steel industry will also face a nastier situation, which will in turn affect the social stability.
Before 2002, iron ore was the absolute buyers market. In order to facilitate the purchase of Chinese enterprises, the three major companies (Rio Tinto, BHP Billiton and Companhia Vale do Rio Doce) at that time even gave a rebate, and the price of iron ore has been relatively low. However, with the rapid economic growth in China, the continuous expansion of production capacity in the iron and steel industry directly led to the soaring iron ore prices (Figure 9). Due to the fact that many Chinese small and medium iron and steel enterprises are not eligible for long-term agreement price, their huge demand has pushed up the price of spot market. From 2007 to 2013, demand growth was too fast, iron ore was in short supply and prices rose sharply. After 2014, due to the newly increased output of iron ore put into operation by the global mining enterprises in 20142015, the supply of iron ore will be oversupplied. Iron ore prices fell for 4 consecutive years, until 2016, however, from 2016, it reversed again. It rose slightly (Figure 9). Over the past 10 years, iron ore prices have experienced two rounds of highs and lows, and the highest point has surpassed 180 US dollars/ton, while the lows have already broken through 50 US dollars/ton.
Iron ore resources in any country belong to the strategic mineral resources, with the interests of nations, in any country are highly concerned about. With the economic development and social construction of third world countries, the demand for iron and steel resources will inevitably increase the demand for iron ore resources. In the future, the emerging economies in the world will compete for iron ore resources more intensively. The high grade and large reserve mines are occupied by the international mining giants. Besides, international mining giants relying on their strong business base for many years, still in the form of acquisitions, mergers and other forms of global search for high-quality iron ore resources, are still constantly expanding their sphere of influence. Chinas steel enterprises that want to get high-quality mines are very difficult. They missed best time to purchase high-quality mines oversea. In addition, Japanese consortium set malicious difficulties to them. Chinas steel mills have paid a huge price for this. It mainly include: (A) the acquisition cost is too high. Currently, the average grade of overseas iron ore resource invested by the Chinese side is about 40%. Although its quality is inferior to that of the United States, Europe and Japan, it is still superior to the domestic iron ore . Overseas mines geographical locations are mostly terrible, need to increase a large number of mineral processing, power plants, water and other facilities investment in construction, development and construction costs will inevitably increase . According to the current investment in projects under construction estimates, the first phase of overseas iron ore development projects to build capacity of 10 million tons of investment is about 2 billion US dollars on average; if it is a low grade one, the investment will require nearly 3 billion US dollars, such as the Guinea project, the total investment of the project has now reached as high as 20 billion U.S. dollars . In fact, most overseas iron ore projects cost more than US $100/ton. (B) Large stake, high risk, hard to quit. Chinese enterprises target for the leading enterprises or the top few companies. Most of these large-scale overseas investment enterprises are state-owned. Because their management does not make money for the purpose of their business, but rather their personal performance as the starting point, they just want to make big achievements, win media acclaim and earn their personal social reputation, resulting in state-owned enterprises inefficiency and the investment frequently failed. For example, Shougang group tried to buy most of all stock right of a Peru company, Aluminum Corporation of China bought Rio Tinto and China Minemetals Corporation bought OZ. In certain sense, all failed. This may give the absolute control over the acquisition of the business, but at the same time will inevitably increase the operational burden. This type of large investment, which concerns only one company, will weaken the risk-resist capability greatly. Once a sharp decline in ore prices, lower profitability, or even loss, companies will be difficult to quit smoothly. Japanese did the opposite. Instead of pursuing the holding of the other sides enterprises, they hold mostly 10% or even lower of the stock of target company. In addition, they did not choose the big ones. The manager of the Japanese company did not seek reputation. Japanese businessmen aim at maximizing business profits, and their business decisions are based on costs and benefits. For example, Mitsui & Co., Nippon Steel and Sumitomo Metal jointly owned Robe River Company of Australian, and then supported the expansion of the company, which indirectly press Rio Tinto and BHP Billiton.
Compared with Japan, Chinas overseas iron ore investment started recently, and is still in the learning stage, compared with Japans investment efficiency and return on investment is still a big gap. Chinese enterprises and the Chinese government still urgently need to learn from Japan on the concept of iron ore overseas investment, management experience and risk prevention.
In order to improve the self-sufficiency rate of iron ore and get rid of the shackles of foreign mining giants, a great deal of research work has been carried out by relevant researchers around the efficient utilization of iron ore resources.
In China, iron ore with hematite grain size of less than 0.045mm or magnetite grain size of less than 0.03mm is commonly referred to as fine-grained iron ore . Yuanjiacun Iron deposit and Qidong Iron deposit in Shanxi and Hunan Province, respectively, are the most typical fine grain iron deposits in China. The Taiyuan Iron and Steel Group and scientific research units, who aimed at the Yuanjiacun iron ore recycle and conduct a large number of experimental studies. The original iron ore grade of 31.18%, 0.045mm particle size accounted for 93.81% of the total ore, they got concentrate iron grade 66.95%, and recovery rate of 72.62%. With this process, the Yuanjiacun iron deposit built a mineral processing plant with annual capacity of 22 million tons by the end of 2012 . Changsha Institute of Mining and Metallurgy proposed a selective flocculation desliming-anti-flotation technology and developed a SA-2 flocculant (for the purpose of fine grain size, complex nature of igneous iron ore in Qidong iron deposit) . At present, the Qidong iron deposit uses this technology to build a beneficiation plant with an annual treatment capacity of 2.8 million tons. Under the conditions of a raw ore grade of 28.36% and a grinding fineness of 0.038mm (98%), the concentrate iron grade 62.5%, the recovery of 68% have been achieved [18, 19, 20]. There are many examples like this. Stage grindingstage magnetic separation likely is the best process for processing fine-grained magnetite [21, 22]; for fine-grained magnetite-hematite mixed iron ore, weak magneticstrong magneticresurfacingreverse flotation process can obtain the high recovery rate; that sorting fine particles hematite process mainly has strong magneticdeslimingreverse flotation [23, 24], selective flocculationreverse flotation  and strong magneticcentrifugal beneficiation .
It would be subdivided into: high-pressure roller mill technology, self-grinding/semi-self-grinding technology and stirring mill technology . The high-pressure roller mill technology is highly dependent on ore ultra-fine grinding equipment: high-pressure roller mill. It is a unit of low energy consumption, high handling capacity. Compared with the traditional crushing equipment, high-pressure roller mill pulverized products significantly increase the internal microcracking, ensure high content of fine-grained fraction and mineral dissociation [3, 27, 28, 29, 30]. Domestic experts and scholars carried out a great deal of research work on the application of high-pressure roller mill technology in iron ore, and formed the crushing-preselection technology of high-pressure roller mill to maximize the crushing and minimize friction in order to reduce processing costs. Masteel company conducted this technic on low-grade iron ore (including high-pressure roller mill, wet grading, coarse magnetic separation pre-selected tail-polishing technology) in Nanshan iron ore deposit, the annual throughput of the beneficiation plant increased by 2.7 million tons, and the electricity consumption and the consumption of steel per unit ore dropped by about 30% . And then, this technology has been introduced into dozens of iron ore processing plants in Hebei Province such as Sijiaying Iron Mine, Panzhihua Iron Mine in Sichuan and Dachang Iron Mine in Anhui . The grain size, grinding and dissociation characteristics of lean hematite ore after being crushed by a high-pressure roller mill have been studied. Details of this technology are still locked. However, compared with the jaw crusher, the high-pressure roller mill has a high crushing ratio, high content of fine-grained, uniform particle size distribution and the Bond power index decreased by 13.9628.23%, 0.5mm grain iron ore monomer dissociation increased by 15.16% . Compared with the conventional three-stage closed-circuit crushing process, the self-grinding/semi-autogenous grinding process has the features of simple process, low capital investment, large-scale equipment efficiency and low dust pollution. At present, China has more than 60 beneficiation plants using more than 160 self-grinding/semi-autogenous mills. For example, Dahongshan Iron Mine of Kunming Iron and Steel Co., Ltd. has used 8.53m4.32m semiautomatic milling + ball milling + ball milling (SAC) process to crush iron ore from 2006 with the processing capacity of 4 million t/a . Stir mill as a fine to ultra-fine grinding equipment was gradually being applied to the fine-graining of iron mines in China [20, 32]. In 2010, Panzhihua Iron and Steel Co., Ltd. purchased three tower mills from Ericsson of Germany for fine grinding of vanadium-titanium magnetite. In July 2013, three tower mills of Dahongshan Iron Ore from Kungang Steel were put into production. In 2013, Ansteel Mining Company purchased six sets of vertical spiral mixing mill manufactured by Metso for the Guanbaoshan Iron Ore Concentrator. Li et al.  explored the possibility of further improving the grade of concentrate obtained by magnetic separation at a grinding stage of a large-scale iron ore mine in Shandong Province. He began with the concentration of iron grade of 62.35% with 0.022mm and access to iron grade greater than 65%. The comparison of mixing mill and ball mill on Shizhuyuan iron deposit, Hunan Province show that: when using a stirred mill, the content of newly formed 0.038mm granular material is 8.1% higher than that of the ball mill, and the monomer dissociation degree of the mixed mill product is obviously higher than that of a ball mill, and the grade of the refined mill product after magnetic separation is 5.2% higher than after ball mill .
In recent years, many domestic research units aim for magnetization roasting technology and equipment and carry out a large number of studies. Flash magnetization roasting technology was one of them, which was proposed by Yu and his team . And then this technology was applied to the Daxigou siderite deposit, Wangjiatan magnetite deposit, and Jielong magnetite deposit, where they obtained iron grade more than 55 and 70% of recovery rate. In 2009, Lingbao plant started the pilot construction of flash magnetization roasting project of 50,000 tons per year. In 2012, the Institute of Process Engineering of Chinese Academy of Sciences built the pilot project of annual handling capacity of 100,000 tons of refractory iron ore fluidized roasting. Northeastern University put forward a complex refractory iron ore suspension roasting technology, and designed a laboratory batch suspension roaster. Using the designed roaster, restricted the air velocity, reducing gas concentration, calcination temperature and roasting time were tested on the positive flotation tailings and oolitic hematite of Anshan Iron & Steel Co., Ltd. at Donganshan Sintering Plant. Under the best experimental conditions, they got iron grade 5661% and recovery rate of 7884% . According to the basic research results, Northeastern University and the Institute of Mineral Utilization of Chinese Academy of Geological Sciences and Shenyang XinBo Industrial Design Co., Ltd., designed and built a 150kg/h complex refractory iron ore suspension roasting pilot system in Emeishan City. In September 2014, the continuous flotation test was carried out with the positive flotation tailings from the tailings of the East Anshan Sintering Factory and the magnetic separation of the tailings of the Ouzanshan Magnetic Puller tailings. The magnetized roasted products produced by this system, after magnetic separation, reached the grade of concentrate iron 6365%, and the recovery rate of 7883%.
For those beyond conventional processing methods and magnetization roasting technology, the relevant domestic researchers put forward a deep reduction-magnetic separation technology that uses coal as an agent to reduce iron ore minerals to metallic iron below the melting temperature of ore, and then promotes the growth of metal iron particles to a certain size. Deep reduction-magnetic separation technology for the development of complex refractory iron ore provides a new way to become one of the hot topics in the field of mineral processing in recent years. Raw materials of oolitic hematite, hematite with carbonate, iron tailings, red mud, Zinc-bearing iron ore were tested by this technic. After the magnetic separation, the deep reduced iron powder with 8595% Fe and more than 90% recovery rate can be obtained . Deep reduction temperature is generally higher than 1000C, iron ore reduction process is Fe2O3Fe3O4FeOFe. The process of reduction can be divided into three stages: initial, middle and late stage. The reaction kinetics models of each stage are Avrami-Erofeev equation, chemical reaction model and three-dimensional diffusion model, respectively. The size of the iron particles in the reduced material can be detected using optical microscopic image analysis techniques. It is noteworthy that the reduction temperature and the reduction time have a significant effect on the size distribution of iron particles .
High-phosphorus oolitic hematite is an important iron ore resource in China. Due to the extremely fine grain size (less than 10m) and high-phosphorus content of hematite, it is difficult to effectively classify the hematite by conventional beneficiation process. However, the deep reduction-magnetic separation process can be applied to high-phosphorus oolitic hematite iron enrichment. The study found that during the deep reduction process, the phosphate minerals in the ore will be reduced to elemental phosphorus, and a considerable part of the elemental phosphorus enters the metallic iron phase, causing high content of phosphorus in the reduced iron powder . In response to this problem, relevant scholars put forward two solutions: deep reduction of dephosphorization and deep reduction of phosphorus-rich . For the raw ore with phosphorus content less than 0.8%, by adding dephosphorization agent (Na2CO3, Ca(OH)2, Na2SO4, etc.) the vast majority of phosphorus remains in the slag phase. This way would get the low-phosphorus deep reduced iron powder (phosphorus content 0.05%) that can be directly used in steel-making . For raw ore containing more than 0.8% phosphorus, by controlling the migration of phosphorus, more than 80% of the phosphorus enters the metallic iron phase. It would get high-phosphorus deep reduced iron powder (phosphorus content 1.5%), and then use smelting dephosphorization technology to deal with high-phosphorus iron powder, and qualified molten steel at the same time get high-phosphorus steel slag, the high-phosphorus steel slag can be used directly as phosphate fertilizer or acid soil improver. Presently, this technic is not yet widely used because of lacking equipment.
Other mineral processing and ore metallurgy technology would include the tailings re-separation technology and room temperature collector technology.  Due to the low grade of iron ore resources in China, an average of 1 ton of iron concentrates needs to be discharged to 2.5 tons of tailings. With the continuous increase of production capacity of mining enterprises, the discharge of iron tailings has rapidly increased and has become the largest industrial solid waste. Tailings discharge not only occupy a large amount of land, sometimes due to poor management, but also cause tailings dam break, resulting in casualties, environmental pollution, destruction of villages and towns and other serious consequences. The iron tailings usually contain a certain amount of metallic iron with a fine grain size, so the energy consumption of grinding is lower than that of raw ore. Anshan Iron and Steel Mining Company, Qidashan iron plant and Gongchangling beneficiation plant conducted flotation tailings re-separation pilot study. The results show that the pre-enrichment of iron minerals in the tailings can be achieved by the re-separation, grinding-magnetic separation and the iron concentrate with grade greater than 40% can be obtained. And then, via the process of grindingweak magneticstrong magneticreverse flotation process or 1 rough 1 fine 1 flotation column process sorting, reaching more than 64% of concentrate grade, the recovery rate more than 88% [38, 39, 40]. Meishan iron ore processing plant integrated tailings, strong magnetic separation tailings, phosphorus tailings on the basis of a comprehensive analysis of mineralogical characteristics of the re-separation were carried out: iron grade of 18% in the tailings can be concentrated to 56.5%. Experimental studies have shown that the nature of iron tailings in different regions vary greatly, hence iron tailings re-separation process is not the same . Most of the domestic iron ore beneficiation plants use an anionic reverse flotation process to reduce silicon, and the collectors used are fatty acids. Anion reverse flotation process has the advantages of stable production, good indicators, the disadvantage is the collector preparation and the required high flotation temperature (preparation temperature is usually 5070C, the slurry temperature is generally 3540C). As the result floating pulp slurry needs heating treatment, which increases production costs . Luo et al.  developed a new modified fatty acid collector, and flotation tests at 25C showed that they got grade of 65.79% with 83.01% recovery rate from the Sijiaying iron deposit. This fatty acid collector has good water solubility and collectibility at room temperature [43, 44, 45, 46]. Aiming at the flotation of iron ore at room temperature, a series of new efficient collectors with low temperature solubility, strong catching ability and excellent selectivity have been developed in China. The efficient separation of iron ore at room temperature has been achieved for some them. However, at present these new collectors are still in the laboratory research or semi-industrial test stage, and the industrial application process needs to be accelerated.
This chapter addresses the topic of iron ore types, structure of import, market analysis, financial aspects, overseas investments, etc. It also covers development of innovative beneficiation processes in China. Probably due to large national land area and multi-period orogeny, from the view of metallogeny, lots of iron deposits developed in China, and the proven total reserves of iron ores are relatively abundant, but mainly low-grade ores. For years, Chinas iron ore reserves are far from being able to meet the requirement of rapid development of steel industry. China is the worlds largest importer of iron ore, which imports accounted for one-third of the worlds total in recent decades; however, the buyer has not the final say. The strategic importance of iron ore resources in national economy not only depends on the social value and economic value created by the iron ore exploitation, but also depends on whether the requirements of the steel industry and steel downstream industry, and safety ensuring, economy and sustainability of steel and steel downstream industry. In order to improve the self-sufficiency rate of iron ore and get rid of the shackles of foreign mining giants, a great deal of research work has been carried out by relevant researchers around the efficient utilization of iron ore resources. In the process of fine iron ore beneficiation, ore crushing, roasting-magnetic separation, deep reduction, tailings re-election, low temperature collector research and development has made achievements.
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