Ore Fractions Research Articles

Utilization of Gamma & Weibull Distribution Functions in Validating Experimental-based Result of Ore Amenability for Coarse Gangue Rejection

Abstract The mining industry faces two-pronged challenges, that is the increasing demand for commodities and declining ore quality, resulting in higher energy consumption and operational costs but poor productivity. Multiple methods have been proposed to address this issue, including early coarse gangue rejection which requires further amenability testing by either experiments and statistical analysis. Experimental approaches, such as Gangue Rejection Amenability Tests (GRAT), have demonstrated efficacy but required substantial time and resources. Statistical methodologies utilizing lognormal distributions offered an alternative, but unable to validate statistical outcomes against experimental results. This study investigated the potential of alternative statistical methods (i.e., gamma and Weibull distributions) to validate GRAT. Through the analysis of grade and density parameters data drawn from eight ore fractions, this research constructed an accurate statistical model for predicting ore separation results. The model’s accuracy was evaluated based on coefficient of determination, heterogeneity of data, and comparison of statistical predictions of cumulative mass and metal yield with laboratory results. The results of employing two distributions did not yield accurate predictions of GRAT results. The statistical values tended to be higher than the experimental results for both parameters. We suggested that alternative functions be tested for more representative and suitable use in coarse gangue rejection applications.

Effect of combined ferrous burden composition and ore-coke interaction on blast furnace burden distribution

The distribution of burden materials at the blast furnace throat is highly correlated with the combined ferrous burden with different mass percentages of sinter, pellet, and lump ore. In this work, the motion behavior of the burden particles was studied under different combined ferrous burden composition, and an analysis was conducted on the cooperative influence of the combined ferrous burden composition and ore-coke interaction on the burden distribution characteristics. The results indicate that the particle flow trajectory is stable when the total mass fraction of pellet and lump ore is less than 32 %. Central coke charging can minimize the radial segregation of the combined ferrous burden. At the ore-coke layer interface, the accumulation and percolation behaviors of ore particles are observed. When the pellet ratio is high, the ore particles can easily penetrate into the void structure of the coke layer.

Laboratory Comparison of Dense Medium Separation and Acid Leaching for Preconcentration of Coarse Rejects from Phosphate Washing Plant

Reverse flotation is a commonly used method for separating carbonate minerals from apatite, but its application to phosphate beneficiation coarse rejects, which are low in P2O5, is often costly due to the high collector dosages used. This study aimed to explore alternative techniques for preconcentration before flotation to improve recovery rates and reduce costs. Our investigation focused on dense medium separation and acid leaching. Dense medium separation, conducted at a cut-off density of 2.76, yielded a preconcentrate with 27% P2O5 and a recovery rate of 90%. The feed material had an initial P2O5 content of 20.52% and a particle size range of +40 µm to −4 mm. In contrast, acid leaching, employing an 8% acetic acid solution over 35 min, yielded a concentrate with 29.11% P2O5, an LOI of 8.99%, and a recovery rate of 100% from an ore fraction [400–200 µm] with an initial P2O5 content of 22.82% and an LOI of 15.78%. Furthermore, integrating flotation and leaching resulted in a concentrate with 32.27% P2O5 and a recovery rate of 98.38%. These findings suggest that combining acid leaching with flotation can enhance P2O5 recovery and reduce processing costs for low-grade phosphate ores.

Acid-Free Processing of Phosphorite Ore Fines into Composite Fertilizers Using the Mechanochemical Activation Method

The relevance of involving substandard raw materials for the production of composite phosphorus-containing fertilizer production is significant due to the problem of providing food products for the growing population of the Earth. The main raw materials for phosphorus and composite phosphorus-containing fertilizer production are natural phosphate ores—phosphorites. However, in the process of mining and crushing, ~55–60% phosphorite ore fines are formed—a fraction of less than 10 mm, which is unsuitable for traditional processing into composite phosphorus-containing fertilizers. This article presents the results of physicochemical studies of the substandard fine fraction of phosphorite ore and the results of the studies of the possibility of their direct processing into phosphorus and composition of phosphorus-containing fertilizers using methods of mechanical and mechanochemical activation in the “Activator 4” planetary mill. The findings of the studies performed confirm the rather high efficiency of phosphorite ore fines’ mechanical activation and phosphorite-containing mixtures’ mechanochemical activation, which make it possible to significantly increase the content of assimilable phosphorus pentoxide P2O5 in composite phosphorus-containing fertilizers. The proposed innovative technology has fundamental differences from existing technologies, since the mechanochemical activation of a mixture of phosphorite ore fines and functional components will allow for direct acid-free and waste-free processing into phosphorus and composite phosphorus-containing mineral fertilizers.

Utilization of polymeric binders to agglomerate oxidized copper ore

Permeability reduction is a major challenge in heap leaching, primarily caused by the accumulation of fines that move with the leaching agent, leading to the formation of dead zones and channeling within the heap. In the Aria copper beneficiation plant, the 0–2 mm fraction with a copper grade of 1.4% undergoes pre-separation prior to heap loading without further processing. This study investigated the potential of using the agglomeration method to improve permeability in the case of using the 0–2 mm fraction of ore. Mineral compounds, such as sodium silicate and calcium sulfate, and non-ionic, cationic, and anionic polymer compounds, were used in the agglomeration process. The strength of interparticle bonding was evaluated by measuring the fine migration percentage (FMP) in the soak test. The results revealed that agglomerates produced using non-ionic compounds had the highest bonding strength, with an FMP of 3.89%, the lowest of all the compounds tested. This enhanced bonding strength was attributed to the combined influence of hydrogen bonding forces and van der Waals forces.

TECHNOLOGY FOR PRODUCING THERMOPHOSPHATE PRODUCTS BASED ON PHOSPHORITES WITH ADDITIVES OF ALKALINE SALTS

The essence of this work is to study the microstructure and mechanical properties of mixed salts of alkali metals, such as sodium and potassium, phosphorites of the Central Kyzylkum of various compositions. This raw material, low in phosphorus and rich in carbonate and chlorine, is not suitable for acid treatment. To obtain high-quality phosphate fertilizers from raw materials, it must first be enriched. At the Kyzylkum Phosphate Plant, multi-stage enrichment is carried out: crushing, dry enrichment, chlorine removal, sintering to remove CO2. One of the promising areas for the processing of phosphate raw materials of this type is heat treatment, based on the destruction of the crystalline structure of the mineral, which is indigestible by plants, during thermal activation. The work is aimed at obtaining a thermophosphate fertilizer, which is insoluble in water at different temperatures and times in optimal proportions with sodium chloride, sulfate, potassium carbonate, chloride, sulfate salts, sylvinite and silicon oxide/coal, which are more active. The regularity of the influence of temperature and weight ratios of the mineralized mass from the fractions of phosphorite ore of the Central Kyzylkum: silicon oxide/coal: sodium salts on the assimilable phosphorus in thermophosphate fertilizer is shown, as well as the fact that the digestibility of phosphorite ore of the II-layer is higher than that of other raw materials. An increase in the content of assimilable phosphorus in synthesized primary phosphorus thermophosphate fertilizers with an increase in temperature and time is substantiated at equal weight ratios of phosphorite ore of the II layer: silicon oxide/coal: sodium salt.

Modeling and Improving the Efficiency of Crushing Equipment

Over the last few decades, the demand for energy-efficient mineral-processing methods has continued. The necessity to develop energy-efficient technologies for the mineral industry will increase in the future, considering the exhaustion of high-quality resources and severe environmental limitations. The subject of this study is crushing equipment. It is a complex of units designed to reduce the fraction of ore and non-metallic solid materials. It is also designed to make them more symmetrical in order to facilitate their transport and later use in production. Thus, the urgency of using crushers in mining and processing plants is clear, so it is relevant to find ways to optimize their operation and reduce energy consumption. This article presents a systematic review of the task of improving the energy efficiency of crushing units. This is achieved by studying modelling methods and results, the automation of crushing and grinding processes, and the wear reduction of crusher components. On the grounds of the reviewed sources, the main methods of increasing the efficiency of crushing units are identified. A mathematical model of the cone crusher was designed. The simulation error is less than 6%. A simulation experiment was carried out on the mathematical model. The dependences of the current and power of the crusher electric drive on the feeder capacity are determined; the graphs have a symmetrical position relative to the approximating curve (R2 ≈ 0.9).

Behavior and Kinetic Mechanism Analysis of Dissolution of Iron Ore Particles in HIsmelt Process Based on High-temperature Confocal Microscopy

In this study, high-temperature confocal microscopy (HTCM) was used to perform in situ observations of the dissolution of iron ore particles in slag at different temperatures. Moreover, the shrinking core model (SCM) is used to explain the kinetic mechanism of the dissolution of iron ore particles. The area of the undissolved fraction of iron ore particles was used to analyze the dissolution rate of iron ore particles. The results show that the kinetic mechanism of dissolution of iron ore particles can be well explained by the SCM. The dissolution of iron ore particles is controlled by the diffusion of iron ore fractions in the boundary layer. The dissolution temperature, the concentration difference of iron ore fraction at the two ends of the boundary layer, and the initial particle size of iron ore particles affect the dissolution rate of iron ore particles. The dissolution rate constant was fitted by introducing a dissolution mechanism. The activation energy of iron ore dissolved in the CaO–SiO2–MgO–Al2O3–FeO slag system is 679.13 kJ/mol. The equation for the dissolution rate constant of iron ore in HIsmelt slag is summarized.

Ion migration in in-situ leaching (ISL) of uranium: Field trial and reactive transport modelling

Acid in-situ leaching (ISL) can be used as a mining technique for in situ uranium recover from underground. Acids and oxidants as lixiviants were continuously injected into a sandstone-type uranium deposit in Bayan-Uul (China). It was conducted to facilitate the dissolution of uranium minerals to generate uranyl ions, which could then be extracted for the recovery of uranium resources by the pumping cycle. A reactive transport model based on PHAST was developed to investigate the dynamic reactive migration process of uranium. The simulated results well reproduce the fluid dynamic evolution in the injecting and pumping units, as well as the dynamic release of uranium. The simulated leaching area indicates that the uranium ore leaching area was much larger than the acidification area. In addition, the pollution plume of uranium and acid water was larger than that of the leaching area, which can be used as a reference for uranium mining schemes. Furthermore, the parameter sensitivity analysis indicates the volume fraction of uranium ore and the reaction rate were the main factors affecting uranium leaching efficiency. Without considering the blockage of pores by precipitation, the Fe2+ in the reinjection fluid had a significant negative influence on uranium leaching.

Determination of yield of fractional material bydestruction of martiteore by water jets depending on the direction of their cutting

Purpose. Highlight the main results of the experiments performed on the destruction of martite ores by the method of borehole hydraulic destruction by their layering. Since, as a result of the analysis of literary sources, it was established that some of the deposits of the Kryvyi Rihiron ore basin are suitable for hydro monitor excavation.Consideration of the method of introducing technologies for hydromechanization of mining operations in the conditions of the Kryvyi Rihiron ore basin is a topical issue. The methods. Using experimental installations conduct experiments on the destruction of layers of martite ores, gradually increasing the water pressure and determine the qualitative fractional yield of raw materials. Mathematical processing of the results obtained and the construction of dependencies based on experiments. Findings. Showing of the sequence of the experiment, the creation of summary tables with the results and the construction of illustrated graphs is the result of a study of determining the yield of fractional material during the destruction of ores by water jets. The originality. Experiments have shown that the yield of the ore fraction during their destruction using the hydro fracture method depends both on the water pressure and on the stratification of the ores. Ores that break down along the layer are more prone to overgrinding, and ores that break into a cross are less likely to. Therefore, the output of fractions during the destruction of layers of martite ores in some values can be controlled. Practical implementation. The development of floodingdeposits of rich iron ores by classical, unsuitable methods is accompanied by a large number of losses of ore raw materials or the impossibility of developing the deposit, because an alternative to the classical drilling and blasting method of destruction of a massif of rock is proposed technology of hydromechanization.The use of borehole hydraulic mining technology will allow the use of water flows from drainage wells or a sump for the safe, non-explosive destruction of the massif. This will increase the safety of mining operations, as well as reduce the seismic impact on the workings before the start of stope extraction.

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.

Полнота использования ресурсов недр и здоровье населения горнодобывающего региона

The study of the biochemical status of the population revealed a decrease in the antiradical activity and inhibition of the oxidase activity. The dynamics of glutathione reductase activity was established, which is a consequence of metal-induced intoxication. Indicators of the health status of the population of mining areas correlate with the number of pollutants entering the environment and the size of the contaminated area. The advances development of metal-induced oxidative stress was established, which reduces the quality and duration of human life. The health of the inhabitants of the mining region and the loss of metals during the extraction of ores depend on the share of dust and fine ore fractions, which, during enrichment end up in waste and are carried by water and wind. It is shown that the minimization of chemical pollution of the environment with metals is possible with the use of technologies that limit the contact of ores with the environmental ecosystems. At the same time, aggressive small fractions do not enter the habitat, and the extraction efficiency increases due to the recovery of the previously lost metals. The technology of leaching metals in the underground blocks was industrially used for more than half a century ensuring in some cases a large share of the production capacity of the enterprises. Leaching in the disintegrators passed the stage of laboratory research on the Sadon polymetallic ores and ferruginous quartzites of the Lebedinskoye deposit. The results of study of the quality of mined ores use, including the effect of dust and fine ore fractions on the health of the population are consistent with the conclusions of the researchers. It is concluded that there is a correlation between the health of residents of residential areas and the quality of mined ores use. Therefore, expanding the scope of metal leaching technologies is the key in solving the problems of rational use of subsoil resources and ensuring the safety of workers.

Actinide concentration from lunar regolith via hydrocyclone density separation

Beneficiation of regolith to concentrate the high-density ore fraction from the gangue can be accomplished through momentum transfer methods, such as ballistic deflection or cyclonic separation.This study explores the extraction of actinide-bearing minerals from lunar regolith based on the difference in apparent density between thorium-bearing minerals (e.g. ThO2ρ=10) from silicates (e.g. SiO2ρ=2.65).Thorium content in lunar regolith ranges from single-digit parts per million (ppm) to as high as 60 ppm.Concentrating thorium-bearing minerals is a required first step in the preparation of fission fuels for a nuclear reactor in which all of the radioactive operations are performed 380,000 km from the Earth’s biosphere. After comparison with ballistic deflection, cyclone separation with a non-volatile fluid carrier was chosen for further study.With sieving to separate particles by size, such a hydrocyclone can be used to efficiently separate the dense fraction from the lighter minerals.Design equations were used to fabricate an at-scale apparatus using water, iron particles, and glass beads as simulants.Results show the ability to effect a 2 to 5.4 % increase in dense fraction concentration each pass, such that 95% concentration requires between 50 and 100 passes, or a cascade of this many apparatuses.The selection of a suitable fluid for safe and low-mass transport to the Moon is part of a techno-economic analysis of the cost and infrastructure needed to produce highly-purified thorium minerals on the lunar surface.

Investigation of the solubility of dust particles in soil solution at different temperatures (on the example of the tailings of the loparite ores' concentration)

A number of large mining enterprises are located on the territory of the Murmansk region. Dusting overburden dumps and tailings storage sites leads to a complex of long-term consequences for the environment. The output of the silty fraction (-0.071 mm) of "stale" tailings of loparite ore dressing (the first field of the tailing dump) is about 22 %. The investigated material is represented by nepheline, microcline, aegirine; loparite, analcime are diagnosed in impurity quantities; the average content of cerium, lanthanum, neodymium - rare earth elements of the light group - 0.18, 0.03 and 0.015 %, respectively. In laboratory conditions, a simulation of the ingress of a fine fraction of loparite ore dressing tailings into the soil has been carried out; the interaction of tailings material with distilled water and water extract from conditionally background soil at different temperatures has been studied. In the course of the study, it has been found that the introduction of dissolved organic matter intensifies the processes of destruction and partial dissolution of the aluminosilicate matrix of rock-forming minerals; an intensive transition of rare earth elements and heavy metals into soluble forms has been recorded. The research results indicate the ecological danger of the finely dispersed material of "stale" tailings of loparite ore dressing due to the ingress of dust particles into the soil and their interaction with soil waters.

Preliminary investigation for beneficiation of Indonesian manganese ore

n this study, manganese ore sample collected from Palludda village, Barru Regency, South Sulawesi Province, Indonesia was investigated. Processing is required to make the ore viable and profitable. The focus of this study is determining the distribution of the assay values among various sizes of manganese ore. On the other hand, to obtain information about its optimum size, which contains the main mineral in a large portion with a small portion of the gangue which consisted in the manganese ore, which defined as the liberation of its main mineral from the gangue. Size assay analysis of manganese ore is of prime importance through which much information can be obtained. The fractioning and chemical analysis are conducted to measure the assay of various minerals and also their distribution in different size fractions. It indicated that manganese and hematite are valuable mineral present, whereas Pb and Zn are the trace element compositions and the gangue mineral that present in the ore is silica. Based on the assay value of each size fraction of manganese ore showed that the maximum liberation of manganese mineral could be obtained at the size range of -20 to +48 mesh. Therefore, further investigation studies on this manganese ore are needed.

Geochemistry and mineralogy of rare earth elements in high-phosphorus ooidal ironstones: A case study of the Kamysh-Burun deposit (Azov–Black Sea iron Province)

This study is aimed at characterizing the distribution and speciation of the rare earth elements and yttrium (REE + Y) in ooidal ironstones from the Kamysh-Burun deposit (Kerch Peninsula), with implications for the depositional environments and contributions of different REE + Y carriers to the ore budget. The Lower Pliocene ooidal ironstone sequence of the so-called Kerch ores, up to 15 m thick, occupies an area of 28 km2. The ore sequence lies between Miocene – Lower Pliocene shell limestones and Upper Pliocene – Pleistocene sandy and clayey sediments and consists of horizontal ooidal ironstone beds composed mainly of goethite and X-ray amorphous Fe3+-(oxy)hydroxides intercalated with siderite and/or rhodochrosite beds. Iron is a main component in ooidal ironstones (50.03–66.19 wt% Fe2O3 and ≤1.61 wt% FeO), as well as in fresh carbonate ores (~34 wt% FeO and ≤14.70 wt% Fe2O3). The Kerch ores contain up to 4.59 wt% P2O5 and show significant positive correlation between P and Fe (r = 0.75). The bulk ore samples and their coarse (1–10 mm) fractions are goethite-dominated and have similar phase, major- and trace-element, and REE compositions. The fine (<1 mm) fractions are poorer in goethite and P2O5 but enriched in SiO2, Al2O3, Ti, Zr, Y, and Th due to greater percentages of Fe-saponite and fine detrital matter (including very scarce rutile, zircon, monazite, and xenotime). The average ΣREE values of 400 ppm in bulk ooidal ironstones and 405 ppm in the coarse fractions markedly exceed those in the Post Archean Australian Shale (PAAS). They have similar PAAS-normalized REE + Y patterns, with moderate enrichment in middle REE (MREE), minor Ce* (0.67–1.09), and moderate negative Y* anomalies (0.57–0.70). The fine ore fractions are markedly enriched in ΣREE (Xav = 858 ppm) mainly due to the presence of authigenic light REE phosphates of rhabdophane-tristramite series with Ce > La ≈ Nd ≈ Ca > Pr > Sm. The ΣREE content in fresh carbonate ores is below that in PAAS (Xav = 103 ppm), but approaches the latter in oxidized crusts (Xav = 178 ppm). The Kerch ironstones also contain REE-poor early-diagenetic Fe2+ phosphate vivianite (ΣREE Xav = 0.93 ppm) and Ca-Fe2+ phosphate anapaite (ΣREE Xav = 6.95 ppm) with typical seawater REE + Y distributions. The ooidal ironstones show MREE-enriched patterns with distinct negative Y* anomalies, which reveals Fe3+-(oxy)hydroxides as chief carriers of adsorbed REE (mainly MREE). The Kerch ironstones accumulated REE progressively due to hysteretic dissolution and precipitation of Fe3+-(oxy)hydroxides in oscillating redox conditions. The diagenetic source of REE stored in ooidal goethite ironstones was inferred from the PAAS-normalized values: CeN/CeN* vs Nd and CeN/CeN* vs YN/HoN discrimination diagrams. In general, the REE + Y budget of the Kerch ooidal ironstones mainly formed during early diagenesis and scavenging from pore water, with a minor contribution of siliciclastic inputs, in the absence of hydrothermalism.

Redox conditions and related geochemical and metallogenic zonation of magmatic rocks of the Sikhote Alin Orogenic Belt

The activity of polyvalent elements in the geochemical processes is to a considerable extent determined by the valence state. A change in the valence is dependent on many factors, but the redox conditions of the medium where magma is generated are considered the main factor. The ratio between divalent and trivalent iron in magmatic rocks is a reliable and an accessible indicator of the redox conditions that determine a whole set of mineralogical, geochemical and physical parameters including ferruginosity of dark-colored minerals, the ore mineral (magnetite–ilmenite) composition, the weight of the ore fraction, and magnetic susceptibility. Based on the above parameters, the zones are distinguished where magmatic rocks of the magnetite and ilmenite series are developed in the Sikhote Alin Orogenic Belt. All known tin and tungsten deposits and occurrences in the Sikhote Alin are confined to the ilmenite series (the axial zone of the belt). The ilmenite rock series are framed by the magmatic rocks of the magnetite series; the epithermal gold–silver and copper–porphyry deposits are associated with these rocks.

Технология разработки сложноструктурного месторождения апатитов и выемочно-сортировочный комплекс для ее осуществления

Development of Oshurkovskoye apatite deposit with conventional methods, using drilling, blasting and then processing of extracted ore by means of flotation and construction of hydraulic structures to store wet tailings, turns out to be impossible, as the reservoir is located in a special ecological zone of Transbaikal; moreover, the deposit has a complex geological structure and a low grade of valuable component in the orebody. Refinement of the mineral product occurs primarily during its processing; however, ore grade can already be controlled in the process of its extraction. Advancement of technical facilities opens up new opportunities of selective mining for complex structure deposits. The purpose of this research is to create a technology, which will upgrade the quality of mineral substance, fed to the processing plant, directly at the extraction stage. The paper proposes a technological development scheme for Oshurkovskoye deposit using an excavating-sorting complex containing a transport-sorting facility and a measuring unit for estimation of the grade in a milled rock mass; it allows to separate a rich fine fraction of substandard ore, which under conventional mining practices would have been sent to the stockpile of temporarily substandard ore. Separation of fine fractions of apatite ore in the transport-sorting facility allows to reduce dusting during production and cuts the losses of valuable component, associated with aeration of fine fractions during loading and transportation of the rock mass. Positioning of oversize material in the open trench with its subsequent selective extraction by the loading machine facilitates non-stop operation of the mining-sorting equipment, which provides an increase in the productivity of mining operations.

Conversion of mineral components manganese ore at temperature conditions of formation of agglomerates

Purpose: to determine the effect of temperature and duration of firing on the dissociation-reduction reaction of mineral components of manganese ores. Recovery of manganese ore is carried out in four stages, which are determined by temperatures: &lt;150°C, 150°C - 300°C, 300°C - 480°C, above 480°C. Topicality. Ores and concentrates undergo a number of complex transformations during heat treatment (agglomeration, firing of pellets and briquettes, preheating). The nature of such transformations is largely determined by chemical, mineralogical and particle size distribution, as well as other properties of the source ore. In addition to external conditions (temperature, pressure, nature of recovery, gas flow rate), the reaction rate is influenced by the physicochemical properties of the renewable substance, its mineralogical composition, structure, surface condition. The kinetic features of the reduction of pure manganese oxides are difficult to apply to manganese ores and concentrates with a rather complex structure and chemical composition. Understanding the basic chemical processes occurring in the smelting of manganese alloys is important for finding and justifying technological solutions to increase the efficiency of smelting of alloys. Method. Kinetic studies at different temperatures and fractional composition of the components under study. Results. The available literature data clearly indicate the dependence of the kinetic parameters of the processes occurring when heating manganese oxides in reducing conditions, from their physicochemical nature. To a lesser extent, process performance differs for natural minerals, although the composition of minerals may vary depending on the place of extraction. In this paper, it seems more appropriate to study the transformations that occur with manganese ores when heated, to use as an object of study the natural minerals that are part of these ores. Experimental data obtained in the study of physicochemical characteristics of the reducing processes of natural minerals can be used in the analysis of ore reduction and improvement of ferroalloy production processes. Scientific novelty. Kinetic studies of the process of interaction of minerals with reducing gas were performed at a constant heating rate of 14 degrees in the temperature range of 25-1000°C. Oxide concentrate and natural minerals lose moisture in the first 5-6 minutes. Their recovery proceeded at high speeds at temperatures of 300-4000C. A significant increase in speed was observed during the transition from a temperature of 4000C to a temperature of 6000C. Subsequent heating at 2000C led to a small increase in the total process speed. The total weight loss of the samples during heat treatment consisted of weight loss due to dissociation of manganese dioxide, weight loss due to dehydration and dissociation of carbonates that are part of the concentrate, as well as oxygen loss due to reduction. Calculations showed that the temperature of the beginning of the dissociation of MnO2 in a helium atmosphere is 460K. Dissociation of pure MnO2 is thermodynamically possible in the studied temperature range. The final decomposition product can only be manganese oxide. Practical significance. The obtained experimental data allowed to draw a conclusion about the inefficiency of grinding of oxidative manganese materials smaller than to the fraction -2.0 +1.5 mm before their heat or reduction-heat treatment in the processes of preparation of the charge for melting manganese ferroalloys. Key words: manganese ore, minerals, dissociation, kinetics, ore fractions

Technology for the production of high-carbon ferrochromium using mono-briquettes

The article presents results of large-scale laboratory studies on the basis of Chemical-Metallurgical Institute named after Zh. Abishev on establishing the possibility of using a mono-charge for smelting standard carbon ferrochromium. Enlarged-laboratory studies were carried out in an ore-thermal furnace with transformer capacity of 200 kVA. Duration of the pilot campaign was 4 days. Three variants of briquettes containing various reducing agents were tested, including: traditional charge (coke PRC + special coke + Borolinsky coal); briquettes with coal from Shubarkol; briquettes with Borlinsky coal; briquettes with coke of China. As a comparative variant, traditional technology with charge materials without briquetting was used. In total, when conducted large-scale laboratory studies it was 41 smeltings. The tests began with a comparative version, which was chosen as technology closest to the technology at Aktobe ferroalloy plant. On the traditional charge, top worked without the uniformly gassing over entire surface of the top. Recovery rate of chromium in the alloy was 79.3 %. Change to briquettes with Shubarkol coal in general has led to the process intensification with more stable current load. The furnace productivity increased to 165.9 kg Cr/day due to increase in the contact surface of reacting phases in briquettes. When using briquettes with Borlinsky coal, satisfactory technological parameters of the smelting process for high-carbon ferrochrome were also obtained, extraction rate of chromium into the metal was 84.91 %. When using briquettes from 0 – 10 mm ore fraction ore and CPR coke in the charge, furnace operation and state of the top were not different from previous periods. The charge also went off evenly, without collapses, the briquettes on the top were not destroyed and current load was highly stable. The work also presents comparative technical and economic indicators for all technologies using mono-charge briquettes.