Ore Fines Research Articles

Relationship of particle size, reaction and sticking behavior of iron ore fines toward efficient fluidized bed reduction

The relationship of particle size, reaction and sticking behavior of iron ore fines toward efficient fluidized bed hydrogen reduction were systematically investigated at 600–800 °C in a laboratory fluidized bed. First, the reduction kinetics were studied, and the results showed that hydrogen reduction of granulated iron ore was controlled by reduction reaction, and the activation energy was approximately 88.4 kJ/mol. The reduction rate of granulated iron ore with a diameter of 200 μm could be increased by 10 times as the reduction temperature rose from 600 to 800 °C. Then, a modified force balance model was established to distinguish the critical sticking point of granulated iron ore during high temperature fluidized bed hydrogen reduction, and it indicated that the defluidization temperature could be raised from 630 to 790 °C as the particle size was enlarged from 100 to 200 μm with a fluidization number of 10. Eventually, coupling the kinetic model and modified force balance model, the maximum gas utilization rate of fluidized bed hydrogen reduction was estimated, and it indicated that at reduction temperatures of 650–750 °C with particle sizes of 200–300 μm, the optimal gas utilization rate could be achieved, which was consistent with the experimental results. Contradictory to traditional understandings of chemical reaction engineering, due to the interaction of reduction performance and sticking behavior, too high of a reduction temperature or too small of a particle size might not be preferable for fluidized bed hydrogen reduction, and this study provided valuable references for industrial operation.

Experimental Investigation of Different Fineness and Firing Temperatures on Pellets Properties of Different Iron Ore fines from Indian Mines.

In India, during mining and ore processing, ore fine generation is a common phenomenon, in which more than 60% of process ore becomes discarded material. To explore the alternative of high-grade ores, mutual replacement with the utility of dump ore fines is the best way. With this perspective, Kiruburu iron ore mine (Iron Ore No.1) and Meghataburu iron ore mine (Iron Ore No.2) dumped fines were chosen for a Blaine no. investigation, in the connection of firing temperatures, to get optimum desirable physical properties, Cold Compression Strength (C.C.S.),and Apparent Porosity (A.P.), with physico-chemical properties, Reducibility Degradation Index (R.D.I.), and Reducibility Index (R.I.). To characterize pellet properties with input variables, a microstructure phase study has been conducted using a scanning electron microscope (S.E.M.), energy dispersive spectroscopy (EDS), and X-ray diffraction analysis (XRD). The Iron Ore No.1 and 2 fine pellets survey showed good, desirable properties, at the Blaine no., of 1678 cm2/g and 2311 cm2/g (corresponding to 200 mesh size), and the best results are attained at a firing temperature of 1300 °C. Thermal kinetic analysis of the heating of pellets has been done to knowthe activation energy of different ore characteristics. The results showed that Iron Ore No.2 pellets have high activation energy.

Beneficiation of Clay-Rich High-LOI Low-Grade Iron Ore Fines: Assessment of Conventional Deep Beneficiation and Magnetization Roasting Using High-Ash Non-coking Coal

Beneficiation of Clay-Rich High-LOI Low-Grade Iron Ore Fines: Assessment of Conventional Deep Beneficiation and Magnetization Roasting Using High-Ash Non-coking Coal

Life Prediction of Iron Ore Tailings Concrete under Freeze-Thaw Cycle Based on Weibull Distribution

It is urgent to improve the comprehensive utilization rate of tailings, especially to solve the problem of fine iron ore tailings treatment and the shortage of natural sand, so iron ore tailings concrete with different replace rates was prepared in this paper. At the same time, in order to further popularize the wide application of iron tailings concrete, it is of great significance to study the frost resistance and life prediction of it in cold regions. Thereby, a series of experimental research on iron ore tailings concrete under freezing-thawing cycles was carried out to analyze the attenuation law of quality, compressive strength, and relative dynamic elastic modulus after different freezing-thawing cycles. In this paper, the relative dynamic elastic modulus was used to define the damage factor, and the freezing-thawing damage model of iron ore tailings concrete was established based on Weibull distribution. Here, the specific function form of two-parameter Weibull distribution of iron ore tailings concrete under freezing-thawing cycle was proposed, and the model was used to predict life of it. The results showed that, compared with the replacement rates of 20%, 60%, and 80%, the iron ore tailings with 40% replacement rate had the best improvement effect on the frost resistance of concrete and can delay the attenuation of the compressive strength of concrete. This model can not only predict the durability life of iron ore tailings concrete under freezing-thawing conditions, but also provide theoretical reference for the application of iron ore tailings concrete in cold areas.

Effect of Extrusion on the Physical and Mechanical Properties of Briquette Made with Blast Furnace Flue Dust and Iron Ore Fines

Effect of Extrusion on the Physical and Mechanical Properties of Briquette Made with Blast Furnace Flue Dust and Iron Ore Fines

Creation of New Adsorbents for the Removal of Emulsified Oil Products from Wastewater Using a Magnetic Field

The synthesis of a complex adsorbent with magnetic properties and a method for removing emulsified oil products from wastewater using a magnetic field were proposed. Fine iron ore concentrate in the form of magnetite obtained by wet magnetic separation of crushed iron ore was introduced as a magnetic load. Breaking steelmaking slag obtained by dry air cooling was chosen as an adsorbing component. Process diagram for treatment of wastewater containing used up cutting-oils was detailed.

Surface Morphology and Structural Evolution of Magnetite-Based Iron Ore Fines During the Oxidation

Abstract The use of magnetite-based iron ore fines by means of fluidized bed technology has become a promising route to produce direct reduced iron. The significant influence of a prior oxidation treatment, which occurs in the preheating stage, on the subsequent fluidization and reduction behavior was observed in our previous study. As a result, it is important to investigate the oxidation of magnetite-based iron ore fines for an optimization of the proposed route. Three magnetite-based iron ore brands were analyzed. The oxidation characteristics are investigated based on thermogravimetric analysis. The surface morphology, structural evolution, and phase transformation were studied with a scanning electron microscope, an optical light microscope, and a high-temperature-X-ray diffraction (HT-XRD), respectively. The three samples showed different oxidation capacity indexes (OCIs) but similar TG-DTG curves. The oxidation rate peaks at around 330 °C and 550 °C indicated the formation of γ-Fe2O3 and α-Fe2O3. The hematite phase shows a particular growth habit. The oxidation first occurs at the surface, forming gridlike hematite structures, and then extends to the inside, resulting in hematite needles. The specific surface area and pore volume decrease significantly due to the sintering effect during oxidation.

Upgradation of Iron Ore Fines and Slime by Selective Flocculation Using Surface-Active Agents, Settling Study, and Characterization of the Beneficiation Waste for Value Addition

Washing of iron ore fines and slime (10% and 25% w/v, slurry concentrations) with two types of surface-active agents (sodium humate (synthesized) and AD 200 (commercial)) at varying concentrations at pH 8 was conducted for ascertaining the efficacy of dispersants in beneficiating the low-grade iron ores. The beneficiation process follows the “selective dispersion-cum-settling technique.” The process results in the formation of a dispersed phase rich in gangue minerals and a settled phase of predominantly active hematite mineral. The stability of dispersed phase (DP) was evaluated by determination of the percentage solid content in the DP. Settling tests were performed. First-order kinetic models have been applied to the dispersion-cum-settling behaviour of both the samples, and evaluated kinetic parameters were found to have good agreement with experimental data. Removal of gangue minerals from iron ore depends on the pH of the slurry, concentration of the slurry, and concentration of the surface-active agent used. The surface-active agents at pH 8 produce ∼1.2–1.5 times more stable suspension in the case of iron ore fines and slimes than that of without surface-active agent. They significantly remove gangue minerals and increase the iron value ∼2–7% with ∼58–74% recovery depending on the experimental conditions. The concentrates collected satisfy the required specifications (Al203/Fe < 0.05 and Al203/Si02 < 1). The gangues in the dispersed phase as characterised by “SEM-EDXA” are mostly clay-bearing minerals like kaolinite, goethite, chlorite, and alumina-silicate minerals. Heat treatment causes distortion of clay minerals present in the dispersed phase and also indicates the complex nature of the gangue minerals.

Direct reduction of fluxed iron ore pellets made from coarse iron ore particles

ABSTRACT The preparation of finer iron ore particles which can be used suitably in pelletization, decreases the binder requirement in the process, but increases the energy consumption during crushing and ball milling. Therefore, using relatively coarser iron ore particles with a suitable binder may help decrease energy input and slag volume. The present study was undertaken for the utilisation of iron ore fines in the range of −0.25 + 0.05 mm along with a suitable binder. Iron ore fines were classified into three size ranges (SR1(−0.25 + 0.1), SR2(−0.1 + 0.05) and SR3(−0.05)mm). Pellets of the above material were prepared using lime as a binder for basicity 0, 1 and 2 respectively, to observe hardening and reduction behaviour. Hardened pellets were characterised using cold crushing strength and porosity. Reduced pellets were characterised using XRD and SEM. It was observed that the cold crushing strength of hardened fluxed pellets decreased from 222 to 12 kg/pellet, and porosity increased from 30 to 43% with an increase in selected particle size. %Reduction increases from 89 to 99% with an increasing iron ore particle size. X-ray diffraction and scanning electron microscopy study confirms the increase in Fe content and iron whiskers growth in reduced pellets with increasing particle size. The optimum property was observed for the SR2 size range with the lime binder, which can produce highly reducible DRI (90–99%).

Analysis of iron ore pellets properties concerning raw material mineralogy for effective utilization of mining waste

The value addition in iron ore mining waste generated from washing or beneficiation plants is a challenging task. The iron ore slimes, which contain low iron content with high gangue minerals like kaolinite, gibbsite, and quartzite, cannot be used directly for iron production. The present study focuses on utilization of iron ore slimes without beneficiation by blending with high-grade fines for making iron ore pellets. The pellets were prepared by adding slimes in different weight proportions (0, 10, 20, 30, 40, and 50%) with high-grade iron ore fines. The high-grade iron ore fines contain 64% Fe, 2.25% LOI, and Blaine number 2975 cm2/g, whereas iron ore slimes contain 52.45% Fe, 5.60% LOI, and Blaine number 7046 cm2/g. Pellets were produced without using bentonite as the binder. The pellet properties, such as drop number, green and dry compressive strength and moisture content of green pellet, cold compressive strength, porosity, swelling index, reduction degradation index, and reducibility index of fired pellet, have been investigated. The pellet mineralogy was analyzed using x-ray diffraction and optical microscope. The empirical correlation has been developed incorporating feed mineralogical data based on kaolinite and goethite to predict the physical and metallurgical properties of pellet.

The changing dynamics of the gas-dust flow in the flash smelter due to addition of a spoiler. Part 2. Pilot tests

The use of man-made deposits and fine ore concentrates in the flash smelter process, as well as the poorer quality of the raw materials observed (due to a higher share of particles smaller than 10 μm) lead to a higher amount of entrained dust and causes accretion in the slag end, uptake shaft and waste heat boiler. A higher dust entrainment is associated with a higher recycle, lower energy capacity of the raw materials and poorer recovery of non-ferrous metals. Numeric modelling of the heat and mass exchange processes in the gas environment of the settler and uptake shaft helped determine how different sizes and locations of the spoiler can change the gas flow parameters of the flash smelter. The modelling study showed that a 500 mm wide (the width of the settler) and 270 mm high spoiler mounted on the fire side of the settler at least 2,000 mm away from the entry to the uptake shaft could help reduce the amount of entrained dust by as much as 20% (relative) depending on the size and density of gas-dust particles. On the basis of the above calculations, a series of pilot tests was conducted on Line 1 of Nadezhda Metallurgical Plant in July 2019. Using various analysis techniques (such as thermal imaging of the surface in the spoiler area, the gas temperature, the gas flow rate, as well as methods used in analytical chemistry, scanning electron microscopy and X-ray spectral microanalysis), the authors of this paper examined the effect produced by the mounted spoiler on the gas flow. The authors would like to thank the leadership and the operations personnel of Nadezhda Metallurgical Plant for their support and great contribution to the pilot tests performed.

Effect of different modification methods on fluidized bed hydrogen reduction of cohesive iron ore fines

To develop breakthrough technologies that enable a drastic reduction in CO2 emissions from the ironmaking industry, the direct reduction of iron ore fines by H2–N2 in a fluidized bed with different modification methods was investigated. The results show that powder coating could prevent the defluidization of cohesive iron ore fines through the physical spacer effect, while granulation modification with cheap cement as the binder not only inhibits the occurrence of sticking, but also greatly accelerates the reduction rate. Microstructure observations indicate that granulation modification has reconstructed the irregularly shaped iron ore fines to be spherical, consisting of small grains, and created porous channels for gas diffusion, thereby increasing the reduction rate. In addition, structure reorganization constructs nonsticking barriers on the surface using native gangue and cement, and the occurrence of defluidization is avoided. Moreover, granulation modification has been demonstrated to be an effective and general solution for efficient and stable fluidized bed reduction of iron ore fines. This makes hydrogen ironmaking through fluidized bed direct reduction technically attractive.

Quantitative Investigation of MgO, Al2O3 and SiO2 Effects on Solid-State Formation of Secondary Hematite in Sintering Process of Iron Ore Fines

Secondary hematite (SH) is a serious factor resulting in reduction degradation of iron ore sinter in a blast furnace; however, until now, a quantitative study for SH formation had not been reported. In this work, the effects of gangue composition, including MgO, Al2O3 and SiO2, on the solid-state formation in the sintering process of iron ore fines were investigated quantitatively. It shows that the SH formation decreased from 67.84% to 46.11%, 35.44% and 22.37% after adding 1.0%, 3.0% and 5.0% MgO, respectively, while for Al2O3, the amount increased to 69.38%, 69.98% and 70.56%, respectively. For SiO2, the amount changed to 68.14%, 61.59% and 47.96%, respectively. Simultaneously, the magnetite (magnesioferrite) formation increased from 8.24% to 34.79%, 50.26% and 70.45% after adding 1.0%, 3.0% and 5.0% MgO, respectively. For Al2O3 and SiO2, the amount changed to 8.95%, 8.37%, 7.62% and 7.62%, 11.10%, 18.77%, respectively, compared with no gangue. This indicates that the SH formation increased with decrease in magnesioferrite. It was found that the decrease in SH formation relates to the diffusion of Mg2+ in magnesioferrite, which inhibits the solid-state formation of SH kinetically. A supposition was suggested that a maghemite existed at a high temperature, and decreased with an increase in MgO addition. This would be another reason to improve the degradation performance of iron ore sinter.

Studies on Performance Evaluation of Modified Polymer on Iron Ore Fines by Selective Flocculation Process

Studies on Performance Evaluation of Modified Polymer on Iron Ore Fines by Selective Flocculation Process

Effect of Iron Ore Pellet Size on Metallurgical Properties

Iron ore pellets are small and hard spherical particles agglomerated from a fine iron ore concentrate. They are used in the blast furnace process to produce hot metal. The diameter of blast furnace pellets is usually between 8 and 16 mm. In this study, a batch of magnesia iron ore pellets was first sieved into particle sizes of 8–10 mm, 10–12.7 mm, 12.7–16 mm and 16–20 mm, and the four different size fractions were used to study the effect of pellet size on metallurgical properties. The metallurgical experiments showed a decrease both in reducibility under unconstrained conditions and in low-temperature reduction-disintegration but showed an increase in cold crushing strength as the pellet size increased. In the reduction-softening test, pellets sized 10–12.7 mm reached the highest final temperature and the highest reduction degree among the pellet samples of different sizes. Based on the implications drawn from this study, the amount of 10–12.7 mm pellets should be maximized in a blast furnace operation.

Development of process for reduction in fines generation at direct reduced iron plant by coating of magnetite iron ore fines on hematite iron ore pellets

Iron ore pellet fines generation at direct reduced iron (DRI) plant is ranging from 10 to 12% during handling of the pellets from pellet plant to DRI plant. The generation of fines during handling depends on the quality of the produced pellets, mainly due to the abrasion index (AI) of the pellet. To reduce the generation of pellet fines, detailed laboratory studies have been carried out by coating the hematite iron ore pellet surface with magnetite fines generated from reduction roasting plant, and mixed magnetite fines with limestone fines. The coated green pellets were fired in a rising hearth furnace. The magnetite fines were varied from 0 to 2.5% as coating agent, and limestone fines was varied from 0 to 0.6% as coating agent mixed with magnetite fines. At optimum 1.5% magnetite fines as coating agent achieved better pellet properties and reduced the fines generation from 6.8 to 3.2% due to formation of secondary hematite phases at the pellet shell. With mixed 0.2% limestone and 1.5% magnetite fines reduced pellet fines generation from 6.8 to 4.2%. Reduction in fines generation with mixed fines was due to formation of secondary hematite and Ca-ferrite at the pellet surface. Secondary hematite and Ca ferrite phases having higher micro-hardness compared to other phases of iron ore pellet. The sequence of micro-hardness of the pellet phases is secondary hematite > Ca-ferrite > primary hematite > magnetite. The secondary hematite and Ca-ferrite formed at the pellet surface due to coating of magnetite as well as magnetite with limestone fines improved the overall pellet quality and reduced the generation of fines at DRI plant. Coating of magnetite fines alone showed better pellet properties with lesser fines generation compared to coating of mixed limestone and magnetite fines.

Reducing effect of biomass derived char on iron ore fines; a statistical investigation and regression modelling

India is an economically developing country. Country’s development and growth is largely interlinked with iron and steel industry as well as availability of energy and its utilization. Energy sector and iron and steel industry mainly consumes convectional and fossil fuel like coal and gas. Present coal reserves of India will last for about 30-40 years at present consumption rate. Consumption of conventional fuels is not economically feasible and environment friendly. Biomass can be an alternative source of fuel for numerous engineering and scientific applications. The char derived from biomass known as biochar can be utilized in the iron and steel-making processes. It can lessen the coke consumption rate and subsequently reduce pollution as well as cost economics. Utilization of low and lean grade iron ore is need of the hour. Removal of gangue impurities from lean and low-grade iron ore is difficult through convectional beneficiation process. The reduction roasting process can be adopted to counter these challenges. The present study focuses on the reduction behavior of iron ore using three various biochar derived from three biomass, viz; wood dust, sugarcane bagasse and coconut shell. A single factorial Design of Experiment with two levels and three variables was adopted and a first-order regression equation was generated to estimate the degree of reduction. The Student’s T-test and Fisher test were performed to validate the regression equation. The obtained results showed that the biochar can be used as a substitute reductant. However, the residence time and temperature play a vital role in the reduction process. The obtained regression equation also validates the effect of residence time and temperature on the reduction process.

Application of an improved mining complex for opencast mining of ore deposits

The purpose of the study is reducing the loss of mineral raw materials and increasing the efficiency of mining operations using a mining complex through the introduction of a new design and engineering solution that improves the equipment functionality. The study involves the analysis of known designs of mining equipment capable of providing the transformation of cyclic scooping of rock mass into its continuous loading, as well as screening of fine fractions from the ore mass. High productivity mining complexes are referred to a promising direction of mining equipment development. The article proposes an improved design of the mining complex, which allows to combine the extraction and loading process and ore mass grading. The improved mining complex is equipped with an annular conveyor with vibrating grids through which fines are screened into the accumulation hopper. From the accumulation hopper the small fractions are sent by means of a pneumatic conveying system to the bunker sections of a special-purpose hauler while the oversize product is loaded into a dump truck by a dump conveyor. The fine fractions of substandard ore collected in the bunker sections are sent for heap leaching. The fine fractions of conditioned ore are sent to the concentration plant to be processed. The proposed design and engineering solution employing an improved mining complex will reduce the cost of works and increase the recovery factor of mineral raw materials in the development of complex-structured deposits of ores characterized by natural concentration of small classes. Removal of fine ore fractions directly during the excavation and loading process can significantly reduce the dusting and decrease the loss of mineral raw materials from blowing and spilling of fine fractions.

A Short Review of the Effect of Iron Ore Selection on Mineral Phases of Iron Ore Sinter

The sintering process is a thermal agglomeration process, and it is accompanied by chemical reactions. In this process, a mixture of iron ore fines, flux, and coal particles is heated to about 1300 °C–1480 °C in a sinter bed. The strength and reducibility properties of iron ore sinter are obtained by liquid phase sintering. The silico-ferrite of calcium and aluminum (SFCA) is the main bonding phase found in modern iron ore sinters. Since the physicochemical and crystallographic properties of the SFCA are affected by the chemical composition and mineral phases of iron ores, a crystallographic understanding of iron ores and sintered ore is important to enhance the quality of iron ore sinter. Scrap and by-products from steel mills are expected to be used in the iron ore sintering process as recyclable resources, and in such a case, the crystallographic properties of iron ore sinter will be affected using these materials. The objective of this paper is to present a short review on research related to mineral phases and structural properties of iron ore and sintered ore.

The changing dynamics of the gas-dust flow in the flash smelter at Nadezhda metallurgical plant due to addition of a shield. Part 1. Model calculations

A poorer quality of the raw materials that go in the flash smelter operated by Nadezhda Metallurgical Plant, as well as the use of man-made deposits and fine ore concentrates with high concentrations of particles smaller than 10 μm, leads to a higher amount of entrained dust. Dust entrained by the gas flow leads to the formation of accretion in the slag end, uptake shaft and waste heat boiler. A higher dust entrainment is associated with higher loads on the gas duct, higher material turnover, decreased performance and recovery of non-ferrous metals. Fitting the furnace crown with a shield avoiding any major changes to the furnace design or the smelting process helps change the dynamics of the gas flow and lower dust entrainment. This paper defines the optimum location and dimensions of such shield. Depending on the particle size and the density of the gas-dust flow, with the shield installed, the estimated reduction in the amount of dust getting in the dust treatment system may reach 20%.