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The fast depleting reserves of high-grade Indian coking coal and its resultant dependence on import makes the emerging situation a fit case for exploring innovative and high efficacy techniques such as non-conventional gravity-based systems for clean coal recovery viz., advanced centrifugal gravity separators like Falcon concentrators for fine and ultra-fine coal particles processing using enhanced gravitational force. The above methodology has been adopted for low volatile coking (LVC) coal due to the high ash content associated washability characteristics and high near gravity material content. Attempt was made using laboratory Falcon SB40 concentrator for cleaning the LVC coals assaying 32.6% ash. Considering the physical properties, coal petrography and washability studies, as received coal was ground to three size fractions of -500 mu m, -250 mu m and -150 mu m and subjected to separation in Falcon separator. Experiments were conducted using Design Expert software to evaluate the effects of four significant process variables such as feed size, pulp density, gravitational force value and water pressure. The relationship between the response functions (ash content, combustible recovery and separation efficiency) and process variables is presented as empirical model equations. Under the optimum operating conditions, LVC coal was cleaned to 18.4% ash content with 57.8% combustible recovery using Falcon concentrator.

Introduction. This work presents the results of the research on the effect the petrographic characteristics, elemental and mineral composition have on the Kedrovsko-Krohalevskoe fine coal beneficiation efficiency. The data has been analyzed of raw coal physochemical properties at the stage of mining and dressing mill raw material base formation. Research objective is to study thermal coal by physicochemical methods of analysis to identify the main parameters affecting the quality of beneficiation products. Based on the data obtained, the research aims to develop the method of assessing the indicators affecting the beneficiation process and further forecasting during the development of new areas and coal seams. Methods of research. The structural features of raw KCN (coking low-caking low-metamorphosed) coal were determined by comparative analysis of three samples according to the following parameters: laboratory flotation results, general technical parameters, maceral composition, organic matter elemental composition, and ash mineral composition. Results. It has been established that coals of a similar nature of origin and stage of metamorphism, can have different indicators in vaarious parameters: particle size, number and morphology of microcomponents according to quantitative petrographic analysis, as well as the presence of hydrophilic functional groups on the surface of coals. Conclusions. The results of the studies made it possible to identify a number of dependencies that can be used in a preliminary assessment of the quality of raw coal sent to a coal processing enterprise.

Coal beneficiation via the air dense medium fluidized bed (ADMFB) has increased its popularity in recent decades. However, due to the coexistence of bubbles and the emulsion phases, obtaining a uniform and stable bed density for coal separation in ADMFB remains challenging. In this work, a coarse-grained CFD-DEM method with high accuracy in capturing the macroscale behaviors of the bed expansion rates and the axial solid concentration, was tested and validated. Besides, the microscale and mesoscale behaviors of the ADMFB were also analyzed via power spectrum density and wavelet decomposition. The findings show that the pressure fluctuation mainly results from bubbles motion of mesoscale rather than from particles motion of microscale and global bed expansion of macroscale. Furthermore, the apparent densities at different scales were calculated and a stable and uniform separation density was obtained within appropriate domains where the coal separation efficiency could be ensured.

The lunar surface is extremely harsh and current mineral processing and metal extraction technologies are not adequately equipped to address this environment. In this paper we review the metals available for extraction and conditions at the lunar surface, and analyse the challenges associated with comminution, beneficiation, and metal extraction operations. The potential beneficial effects of the natural lunar conditions are also evaluated. This investigation concludes that process plant design on the lunar surface will favour lightweight, schematically simple flow sheets that enable automation, and that utilise the local environment wherever possible. The elimination of traditional comminution and beneficiation stages and their replacement with basic classification could be economically favourable. The most promising metal reduction pathways are identified as molten regolith electrolysis, and vacuum thermal dissociation, other processes with merit are hydrogen reduction, carbothermal reduction, and solid electrolysis. Finally, it is identified that a significant research effort in all areas of astrometallurgy will be required before industrial-sized extra-terrestrial mineral processing and metal extraction operations will be viable., 31 Pages, 5 Figures

Recent technological and industrial developments in applications of Nb as well as its demand by aviation, communication, electronics, atomic and nuclear energy, metallurgical and steel industries h...

Current advances and developments in automated mineralogy have made it a crucial key technology in the field of process mineralogy, allowing better understanding and connection between mineralogy and the beneficiation process. The latest developments in X‑ray micro-computed tomography (µCT) have shown a great potential to let it become the next-generation automated mineralogy technique. µCT’s main benefit lies in its capability to allow 3D monitoring of the internal structure of the ore sample at resolutions down to a few hundred nanometers, thus excluding the common stereological error in conventional 2D analysis. Driven by the technological and computational progress, µCT is constantly developing as an analysis tool and successively it will become an essential technique in the field of process mineralogy. This study aims to assess the potential application of µCT systems, for 3D ore characterization through relevant case studies. The opportunities and platforms that µCT 3D ore characterization provides for process design and simulation in mineral processing are presented.

Since coal washeries generate huge quantities of high-ash rejects as waste, effective utilization of coal rejects help in sustainable coal preparation. Out of different coal rejects, tailings from froth-flotation process can be a potential material for the extraction of clean coal due to its fine size, availability in the slurry form, presence of good carbon values, and better liberation properties. In the present study, three different methodologies i.e., chemical method, chemico-physical method, and physical method are explored to separate clean coal with >49.8% yield for their utilization in coke making process. The chemical method of demineralization by alkali-acid leaching shows a high clean coal yield of 65.4%; however, the alteration of vitrinite-group macerals makes it unsuitable for coke making process. Chemico-physical method of clean coal separation by hydrothermal extraction followed by density separation results in clean coal at 49.8% yield with an increase in vitrinite group macerals, which shows a positive impact on rheological and coking properties. The physical separation method by ultrafine grinding followed by density-gradient-centrifugation resulted in 58.2% of clean coal yield with coking properties similar to the clean coal obtained in conventional coal beneficiation plants. By adopting chemico-physical method and physical method of coal cleaning, the overall clean coal yield of the washery can be improved by >5.1%. Also, there is no deterioration in coke properties such as coke strength after reaction and coke reactivity index by using the prepared clean coal in coal blend.

Gas-solid fluidized bed is an effective dry method for beneficiation of −6mm fine coal, belonging to Geldart D particle. Due to the density difference of concentrates and gangue in the raw coal, th...

The control of chromite feeds is supported by alternating modes of operation that respond to imbalances in feed stockpiles. Conventional classifications of chromite relate to its end uses: metallur...

In this study, the simulation of a newly designed wind-sifter separator for dry beneficiation was deployed to upgrade -6.7 + 3.36, -3.36 + 1, and -1 mm coal. The wind-sifter principle is very effective for particle separation as it is based on the separation of lighter particles from heavier ones. First, the study entails computer simulations by utilizing the Lagrangian particle tracking method to observe the effectiveness of the wind sifting principle in separating particles based on their density in an air stream. From the three particle size fractions used, the simulation test results show that at a cut-point of 1.5 RD, yields of 29.1, 54.3, and 99.4% were attained at different optimum velocities for -6.7 + 3.36, -3.36 + 1, and -1 mm, respectively. The effect of operating parameters such as the mass flowrate and air velocity on yield, ash content, and calorific value were determined using the fabricated separator. A preliminary experimental study showed that the separator was effective in upgrading the feed coal with 30.28% ash content and 21 MJ/kg calorific value to clean coal with 18.94% ash content and 26.8 MJ/kg calorific value. A laboratory-scale wind-sifter separator was fabricated based on the results from the simulation test, which served as the first applied prototype in the field of dry coal beneficiation.

This study investigated the segregation of organic (maceral) and inorganic (mineral matter or ash) contents of coal in an air stratifier after design modification in air distributor. The optimum angle of fluidization caused by air distributor was found using mathematical formulations of momentum balance on particles, and 30° of angle of fluidization was found to be the optimum angle of fluidization. Using coal feed with 32.64% ash content, the stratification time in the air stratifier with 30° angle of fluidization was estimated using phase distribution studies and the stratification time was found to be 12 min. The time at which concentrate has high organic phase as well as low inorganic phase and, simultaneously at that same time, the reject has high inorganic phase and low organic phase was fixed as the stratification time. Comparative studies with two different coal feeds were done for conventional fluidization and angular (30°) fluidization. The latter was obtained by design modification of air distributor and was found to enhance dry beneficiation of coal in air-pulsated stratifier.

In coal beneficiation, ash content is the main focus area as it plays a vital role in controlling the yield and quality of the washed clean coal. Indian sub-bituminous and bituminous coals are of l...

In the booming electric vehicle market, the demand for refined cobalt is showing a blowout growth. China is the largest cobalt-refiner and cobalt-importer in the world. However, the life cycle inventory and potential environmental impact from cobalt refining in China have not been clearly illustrated. This paper builds a comprehensive inventory to support the data needs of downstream users of cobalt sulfate. A “cradle-to-gate” life cycle assessment was conducted to provide theoretical support to stakeholders. A life cycle assessment was performed based on ISO 14040 to evaluate the potential environmental impact and recognize the key processes. The system boundary of this study contains four stages of cobalt sulfate production: mining, beneficiation, primary extraction, and refining. Except for the experimental data used in the primary extraction stage, all relevant data are actual operating data. The normalization value was calculated based on the latest released global emission and extraction data. Normalization results show that the potential impacts of cobalt refining were mainly concentrated in the fossil depletion and freshwater ecotoxicity categories. The beneficiation stage and the refining stage account for 72% and 26% of the total normalization value, respectively. The beneficiation stage needs to consume a lot of chemicals and energy to increase the cobalt content, due to the low grade of cobalt ore in China. Compared with cobalt concentrate, the use of cobalt-containing waste (e.g., cobalt waste from EV batteries) can ease endpoint impact by up to 73%. With the application of the target electricity structure in 2050, the potential impact of China’s cobalt sulfate production on global warming, fossil depletion, and particulates formation can be reduced by 24%, 22%, and 26%, respectively. Findings indicate that the chemical inputs and electricity consumption are primary sources of potential environmental impact in China’s cobalt sulfate production. Promoting the development of urban mines can reduce excessive consumption of chemicals and energy in the beneficiation stage. The environmental benefits of transforming the electricity structure and using more renewable energy to reduce dependence on coal-based power in the cobalt refining industry were revealed.

An analysis of the operational conditions for utilizing a small-volume blast furnace (BF) both in metallurgical production and processing of resulting wastes is carried out. Micro blast furnaces can be recommended for integrated waste processing in metallurgical production and coal benefication due to the small effective height of the furnace (no more than 10–12 m) reducing the strength requirements of products following compacting operations for obtaining pellets or briquettes. On the example of a complex equipped with a 70 m3 micro-blast furnace, the application of carbon-containing pellets obtained from metallurgical production and coal benefication sludges was shown to result in reduced unit costs for the production of 1 ton of cast iron. However, for stable furnace operation, it is necessary to resolve outstanding problems involved in the preparation of ferrous wastes for the subsequent manufacture of carbon-containing pellets.

Globally, waste electrical and electronic equipment is one of the fastest-growing waste sectors. Mobile phones constitute the major portion of the telecommunication e-waste category. Over the years, waste mobile phones were considered as a potential source of secondary metals. This study aims to determine the physical and chemical composition of the discarded mobile phones and to evaluate its recovery potential. The printed circuit boards from the discarded (waste) mobile phones (MPCB) were collected and samples of different sizes 3 × 3 cm, 2 mm, 1 mm, 500 µm, and 150 µm were obtained after milling and sieving. Elemental composition revealed the presence of base metals, Cu, Zn, Fe, Ni, and Pb, in higher quantities with a significant amount of precious metals Au and Ag. Amount of base metals present in different MPCB size fractions was found in the order 3 × 3 cm2 mm1 mm500 µm150 µm. The amount of precious metals like Ag and Au was found to be higher in large-sized MPCB fractions. FTIR studies declared the presence of polymers like ABS, PC, and HIPs in MPCB samples. TCLP tests for toxic metals revealed that MPCBs contained high concentrations of cadmium, lead, and mercury highlighting their hazardous potential. The ultimate analysis revealed that NMF has a GCV of 12.34 MJ/kg and a volatile content of 42.25%, which can be a potential source of energy that can be recovered through the gasification or pyrolysis process. Overall, the comprehensive characterization of waste MPCBs will systematically provide a better understanding of e-waste recycling processes for beneficiation purpose and sustainable resource utilization.

Beneficiation of low-grade ore is of critical importance in order to meet the growing demand for coal and mineral industries. But, low-grade ores require fine grinding to obtain the desired liberation of valuable minerals. As a result, production of fine particles makes the beneficiation process difficult through conventional gravity separators. Hence, alternative beneficiation techniques are being investigated for upgradation of metal values from low-grade ores. The gravitational force effecting the separation is replaced by the centrifugal force to usher in enhanced gravity separators. The objective of the present paper is to summarize the applicability aspect of enhanced gravity separators for different mineral systems including non-ferrous, precious, ferrous, and industrial minerals. These mineral systems include run off mine ore, secondary products like tailings and plant slags, etc. For this purpose, the design, operational features, types, and separation mechanism of enhanced gravity separators, such as Falcon concentrator, Knelson concentrator, multi-gravity separator (MGS), and Kelsey Jig, are discussed. Based on our review, research scope and future possibilities of enhanced gravity separators are also proposed.

The present paper outlines the work done on beneficiation of low-rank-oxidized coal fines by flotation using a biodegradable oil (iluppai or Mahua) to reduce the ash content. Prior to flotation, ch...

Herein, an innovative approach for determining the grinding media system of ball mill based on grinding kinetics and linear superposition principle was proposed. The optimal media ball size of −2 + 0.45 mm, −0.45 + 0.15 mm, and − 0.15 mm feeding samples were 40 mm, 30 mm, and 30 mm, respectively. According to the linear superposition principle, the media size ratio is equal to the yield of ores. The optimal media proportion was φ 50 mm: φ 40 mm: φ 30 mm = 28%: 28%: 44% via wet grinding experiment, in which the yield of qualified granular material (−0.074 + 0.03 mm) suitable for beneficiation was the largest in the ground products. The optimized space-filling factor and material media ratio was 35% and 1.0 through the wet grinding experiment. According to the energy consumption method, the mathematical function models of installed power and mill productivity vs. space-filling factors were established to calculate the installed power and productivity of an industrial ball mill (Φ5.03 m × 6.40 m).

It is obvious that, for any country that is anticipating to be successful in today's end-users' community, that country's sectors' managers need to apply some sufficient efforts in order to render assistance to the indigenous mining companies to outcompete the other firms in the region. Among many possible activities, cost reduction in mineral beneficiation is regarded as one of the core areas presenting enormous opportunities for the West country, Liberia. The country like Liberia who is endowed with an impressive stock of mineral reserves and has traditionally relied on mining, namely iron ore, gold, and diamonds, as a major source of income is not exempted.

Generation of waste from the agro-processing industry is continually increasing due to increasing needs for food security. Beneficiation of this waste has both economic and environmental impacts that can be overcome via implementation of cleaner production technologies. Starch is a renewable biopolymer material which is completely biodegradable, easy to handle and widely available in nature. It has wide applications in various industries including food processing, pharmaceutical, confection, beverage, pulp and paper, chemical, cosmetic, binder and adhesive, packaging and printing, fermentation and textile industries. We have previously demonstrated that high-quality industrial-grade starch can be extracted from waste avocado seeds. This report is focussed on a techno-economic evaluation of the extraction process. It can be concluded, from the study that extraction of starch from waste avocado seeds is economically feasible with an accounting rate of return of 75% and a break-even analysis of 82% with a payback period of 2 years. The process is environmentally sustainable in that minimal amounts of chemicals are used in the extraction process and the wastes generated can be beneficiated into high-value products that can add further to the profitability of the venture.

In many parts of India, because of depletion in high grade iron ore, efforts are focused on the use of low-grade iron ore for steel production. As an alternative iron source, low-grade banded iron ores have attracted attention. The beneficiation and utilization of banded iron ore is closely connected to their mineralogical characteristics, nature of impurity inclusion and liberation behavior. Characterization studies indicated that ore was low in iron value (~ 36.5 wt%), and contained high amount of silica (~ 46.3 wt%), which made it difficult to process by conventional beneficiation method. Therefore, we used reduction roasting method on the ore to produce the pellet feed material. Different process parameters such as roasting time, temperature and coal-ore ratio were optimized to achieve the maximum recovery and grade of magnetic product. Using coal as reducing agent, the optimum condition was found to be as, reduction temperature: 900 °C, time: 90 min, and coal-ore ratio: 15%. Under the optimum condition, maximum recovery and grade of magnetic product were found to be 72% and 65%, respectively.

Primary economical deposits of rare-earth elements (REEs) are exhausting all over the world, and it has become necessary to find new sources and methods for their extraction. In addition, increasing the application of REEs in modern technological society has increased its demand globally. One of the important movements to compensate for the future shortages of critical metals is the recovery of REEs from recyclable materials. This paper presents a review of the classification and extraction methods, as well as general applications of REEs with emphasis on secondary sources such as coal and coal byproducts, iron ore tailings, apatite, and phosphate byproducts. An overview of the current state of knowledge on the various methods of REE beneficiation and extraction is covered. These methods include physical separation, as well as hydrometallurgical and bio-hydrometallurgical techniques. The application of these REE extraction techniques for enhanced recovery has been driven primarily by the unique industrial application of these important elements. This paper further explores the existing and potential environmental challenges associated with REE extraction. The authors have presented a wide array of literature, in-depth discussion of the subject, and a succinct summary of processes and relevant case studies.

In India, the use of iron ore pellets in the blast furnace, electric arc furnace, or sponge iron production is continuously optimized, considering different aspects of the production chain from the run of mining (ROM) to metallic iron depending upon the industrial need and ore availability (recent aggressive iron ore mining auction 2020 in India). The scarcity of high-grade iron ore resource and availability of the considerable quantity of low-grade iron ore fines, banded hematite quartzite (BHQ) ore in mines (mostly in Bihar, Odisha, Madhya Pradesh, and Karnataka), has to lead the way to beneficiate and utilized the concentrate as pellet feed for the steelmaking process. Banded iron ore such as BHQ is one of the potential resources of iron having a total iron content, i.e., Fe (T) of 35–48 wt%, which is lying unutilized in most of the Indian iron ore mines. The challenge before the policymakers and researchers is to think of a sustainable process technology to utilize these iron ore resources wisely. The conventional beneficiation of this type of siliceous BHQ iron ore resource having low iron content is not advisable. Therefore, pelletization of synthesized magnetite concentrate obtained from the magnetization roasting of BHQ emerged as an alternative energy-saving and ore conserving process that may be scaled up and commercialized for low-grade banded iron ores. The pelletization of magnetite concentrate is an independent heat hardening process; thereby requirement of anthracite coal fines as a fossil fuel additive to maintain the temperature gradient from core to the periphery of the pellet can be avoided. Physical properties such as cold crushing strength (CCS) and porosity of the pellets were optimized to study their suitability in the steelmaking process. In this regard, characterization studies of the pellets were performed using X-ray diffraction (XRD), scanning electron microscope (SEM), optical microscope, and X-ray micro-computed tomography to understand the microstructural properties of the pellets. The CCS of 255.8 kg/pellet and porosity of 25.42% were achieved at the optimized induration temperature and residence time of 1250 °C (50 °C to 80 °C less than conventional hematite pellet induration) and 10 min, respectively. The properties studied are encouraging and comparable with the pellet prepared from the natural magnetite/hematite ore.

The long-term work experience of domestic specialists in the formation of coal fuel briquettes from carbon-containing waste of coal mining and coal benefication was generalized. Scientific approaches to the selection of coal materials, binding systems and special technological additives for the production of high-quality briquettes with various properties were presented. Organizational methods of solving this complicated ecological problem of the coal industry were formulated.

Separation of fine particulate solid materials is one of most important unit operations in industry. Utilization of gas-solid fluidized beds has been considered where particulates are released from constraints due to contacts with surrounding particulates and segregation occurs according to density, size or combination of density and size. Addition of mechanical vibration to the gas-solid fluidized bed may improve dry solid separation. In this study, we investigated the dry separation characteristics of solid particulates using a vibro-fluidized bed especially focusing on the separation of fine particulate ores (≈100 μm) with small density differences. At first, we focused on the influence of fluidizing air velocity on the efficiency of segregation. Subsequently, the influence of vibration strength, vibration amplitude and frequency on segregation behavior was investigated. We found the density segregation does not occur with either gas-fluidization or vertical vibration alone. Only the combination of these effects produces density segregation. The fluidizing air velocity is an important factor to enhance the density-segregation of the particulates with small density difference.

The effective disposal of ever-increasing electronic waste (e-waste) is one of the grand challenges for the scientific and technological community today. As e-waste has exponentially been increasing the burden on our environment with long-term effects on the ecosystem, the need for finding sustainable means to recover, reuse, and recycle the materials available in the e-waste is much sought after in the present time. In this background, we demonstrate an easily scalable green route for the beneficiation and effective usage of metallic materials from the e-waste using cryo-temperature grinding with the primary objective of retrieving the near-full metallic residue from e-waste by an energy-efficient and eco-friendly approach. The metallic nanoparticles thus obtained are subsequently utilized for the selective reduction of CO₂ into different gaseous products via the electrochemical route, leading to the evolution of CH₄, H₂, and CO as major gaseous products at neutral pH and CO as the major product at basic pH. In a nutshell, the current approach can provide useful means for achieving major metallic residue from the e-waste, which can further be utilized for green energy production in an eco-friendly manner, making the process sustainable.

Grinding aids (GAs) have been an important advent in the comminution circuits. Over the last few decades, in order to address the high energy consumption and scarcity of potable water for mineral processing, chemical additives have become a promising alternative. Using GAs can have some advantages such as enhancing grinding efficiency, reducing water usage, improving material flowability, and narrowing the particle size distribution of the grinding products. A study on the effect of GAs on size reduction units is crucial for the beneficiation value chain of minerals and the impact on downstream processes. However, our understanding of the effects of these materials on the particle size reduction is quite limited. This article analyses the literature, which used GAs and provides a comprehensive review of their applications in the ore beneficiation processes. The outcomes of this investigation indicated that the current understanding on the mechanism of GA effects focuses only on their impacts on the product fineness and size distribution, and neglecting the aspect of energy expended and physicochemical environment. The application of GAs is mainly for rationalisation of energy where the type of reagent, pH, and ionic strength of the grinding environment is important. Gaps in knowledge of GAs are discussed in the context of addressing their use in the mineral industry, considering the mechanism of their effect, effect on grinding efficiency, and effect on the downstream processes. Addressing these gaps will pave the way for the application of GAs in improving size reduction efficiencies, which ultimately reduces environmental impacts.

Abstract Hard coal is an important source of energy worldwide. Owing to the imperfections of excavation technology, most run-of-mine coals must be processed before they can be utilised as fuel. In this study, tests on the dry separation process were performed with numerous different raw hard coal and coal waste material samples, using a newly designed and constructed negative-pressure pneumatic separator (NPPS). The experiments revealed the effects of the feed-material properties and material processing conditions. These experiments were preceded by additional tests for evaluating the influence of each device operating parameter on the process, to determine the optimal method of supplying the feed material. The calorific value of the processed materials was improved by 5%–40%, while a minimal output yield of products (60%–70%) was maintained. The trials indicated that in coal material processing, the developed NPPS can be used for not only raw coal enrichment but also coal recovery from materials stored at coal-waste dumps. The main advantages of the device are its mobility, low material processing cost, and lack of water consumption during operation. Graphic abstract

Particle mixing and segregation behavior in an Air Dense Medium Fluidized Bed with binary mixtures of solid particles were investigated for dry coal beneficiation. Magnetite mixed with coal/gangue/sand particles belonging to Geldart B/D group were tested individually for the bed density adjustment. The effects of operating parameters including particle density ratio, particle size ratio, mixture composition, superficial gas velocity, and fluidized bed height on the mixing and segregation pattern were examined. The results demonstrated that the segregation becomes more severe with increasing density difference of binary mixtures. An increase in particle size ratio may also lead to partial segregation. Mixing and segregation of binary systems are almost independent of lower excess gas velocity and initial bed height when it is over 15 cm. Moreover, a mixing index was employed to evaluate the mixing and segregation performance, and the criteria for good mixing to achieve the bed density adjustment were identified.

The coking behavior of coal is an important facet in utilization of coal in metallurgy and in other industries. The carbonization behavior of coal mainly depends on coal rank, petrographic composition, ultimate composition and rheology of coal. Coal petrography has become very useful technique for establishment between formulation of coal blend composition and coke quality prediction. It is generally established that blend containing optimal reactives produces the coke of maximum strength. The coking properties of coal not depend only on the macerals composition, but also on the way in which the macerals are distributed among one another, forming preferential associations called microlithotypes. The measurements of relative proportion of microlithotypes are called microlithotype analysis. In present work, distribution of macerals (microlithotype) in coal samples were studied and correlated with the coke quality. Beneficiation by wet method were carried out (only indigenous coal) by washing media of specific gravity 1.30 to 1.40 to achieve

The current study investigates the beneficiation of iron ore fines by the carbothermal process using muffle and microwave furnace. The muffle furnace reduction was found useful for the separation of iron-bearing phases from the quartz impurities and concentrate with iron purity of ~ 64%, recovery of 98%, and a yield of 84.5% is achieved at 900 °C, 9% charcoal in 1 h. Incorporating coal as a reductant followed a similar trend as charcoal, although the leaner reduction rate leads to limited fayalite formation and, consequently, better magnetic property at a higher temperature. The microwave exposure of ore led to a temperature of ~ 750 °C in 15 min, and the ore-reductant mixture attained 960 °C with charcoal and ~ 800 °C with coal. The microwave reduction yielded comparable concentrate iron grade-recovery with muffle furnace reduction at comparatively lower carbon dosage (6%), suggesting better carbon utilization. Meanwhile, coal-based microwave reduction followed the opposite trend as muffle furnace reduction, and iron grade decreases with an increase in carbon dosage. The optimal conditions of 6% charcoal and 800 W yielded concentrate of 63.8% Fe, 99% recovery with 87.4% product yield. The maximum separation efficiency of the muffle furnace reduction is 80% at 1000 °C with 18% charcoal compared to 70% in the microwave at 6% charcoal, indicating the latter route is efficient and economical. The separation efficiency remains unaltered with carbon dosage suggesting minimal carbon required for achieving maximum separation is 6% C. The metallization of the product of microwave reduction was the functionality of reductant dosage and increases exponentially with carbon dosage. The ferrite formation is initiated at 12% C with maximum metallization of 38.5% at 27% charcoal and 900 W power. The maximum metallization in muffle furnace reduction is 16% at 1000 °C and 18% C. The techno-economic comparison indicates incorporating microwave reduction reduces processing time by 25%, and the carbon consumption is reduced by 35.5%.

This paper investigates the air dense medium fluidized bed (ADMFB) as a suitable dry beneficiation technique to upgrade +5.6 mm-13.2 mm South African coal. The separation efficiency of the ADMFB was assessed by determining the effect, if any, of particle size range, medium to coal feed ratios, and the addition of vibration on the separation ability of the bed. The coal was upgraded to varying degrees, depending on the parameters of the applied methods. For example, when considering the bottom bed layer (one quarter of the total bed height) as discard, the cumulative ash yield of the clean coal fraction ranged between 13.0% and 17.6% with a corresponding yield of 82.21%–83.93%, respectively. A variation in feed coal PSD did not significantly influence the response of the bed pertaining to its ability to beneficiate the coal. This was quantified by the similarity in percentage ash yield for the feed, top and bottom layers. In addition, it was established that by feeding a coal and magnetite (+300 µm) mixture, in various mass ratios, did not significantly influence the separation efficiency of the bed, nor did the application of external vibration to the bed aid in the beneficiation of the coal. Although these factors did not influence the performance of the ADMFB, it was found that the minimum fluidization velocity and bed stability were largely improved by the introduction of these variables

Processing of noncoking coals in India is limited due to the high cost involved in wet processing. In the present study, dry beneficiation of two high ash Indian non coking coal samples from two di...

The beneficiation of low-grade iron ores to meet the growing demand for iron and steel is an important research topic. However, certain ores do not qualify to be treated in physical separation processes, and hence, alternative strategies are being looked into for upgrading their iron content. The objective of this review article is to compile and amalgamate the crucial information regarding the beneficiation of low-grade iron ores using carbothermic reduction followed by magnetic separation, which is a promising technique to treat iron ores with complex mineralogy and liberation issues. Reduction roasting studies done for different types low-grade iron ores including oolitic iron ores, banded iron ores, iron ore slimes and tailings, and industrial wastes have been discussed. The large scale technological advancements in reduction roasting and the possibilities of the application of alternative reductants as substitutes for coal have also been highlighted.

This work explores the use of carbon dioxide, water, and their mixtures as solvent for the precombustion beneficiation of raw coal without using any toxic mineral acids in the temperature range of 200–400 °C. The fluid polarity, ionic constant, and supercritical point can be adjusted by H2O/CO2 ratio and temperature. Adding carbon dioxide to hydrothermal fluid also increases the ionization by forming carbonic acid. Extractions with supercritical fluids have several benefits including enhanced mass transport, ease of separation and recycle, wide range of extractive capability and tunability, better inherent safety, and in the case of carbon dioxide and water–low cost. A semi-continuous extraction system was designed and built in which pressure, temperature and the relative flow rates of CO2 and H2O can be controlled. Coal powder is kept in a packed bed and the extraction is carried out at 143 bar pressure. Using sulfur as a model heteroatom, extractive efficiency is examined as a function of the temperature, fluid composition, fluid flow, and extraction time. The results indicate that carbon dioxide, water, and supercritical water-carbon dioxide (ScWC) all can effectively extract about 50% of total sulfur from bituminous coal in 1 h. Extraction above 350 °C decreased effectiveness, and extraction above the supercritical point of pure water caused hydrothermal carbonization. ScWC extraction may provide necessary control to prevent organic dissolution while removing sulfur.

India has vast coal resources all over the country; however, the presence of high ash content makes them invulnerable for industrial usage. To compensate for the rapid depletion of high-quality coking coals and to compensate for the demand for coal in iron and steel sectors, coal cleaning or beneficiation and blending techniques have come into limelight for the usage of low-quality coal. In this paper, laboratory-scale experiments were performed on the utilization of Indian high ash non-coking coal (NCC) and imported semi-coking coal (SCC) for the coke preparation. At first, washability characteristics of Indian high ash coal were investigated by using jigging, spiral concentration, and sink and float density separation methods. The optimum cut-off density NCC and SCC coals were blended and sent for the caking properties analysis. Proximate and ultimate analysis, vitrinite reflectance, crucible swelling number, and caking index or roga index have been taken as the measure for the caking ability of coal blends.

Coal preparation plants commonly use density-based separators to remove high-density inorganic matter (rock) from low-density carbonaceous matter (coal). Liquid–solid fluidized bed separators (FBS)...

The question of harnessing Africa’s natural resources has been widely debated, with an increasing recognition of the importance of linkage development between commodities and manufacturing for sustainable resource-based industrialization. However, while linkages arising out of high-value mineral resources are at the core of academic attention, opportunities arising out of so-called ‘low-value minerals’ have often been neglected. This paper aims to contribute to the recent efforts attempting to fill this gap by evidencing the ways in which industrial minerals and construction materials can be used as inputs for economic development. More particularly, this paper will do so by examining the mechanisms and industrial strategies behind the development of linkages between these Development Minerals and the manufacturing and agricultural sectors in Africa. This paper starts by laying out a theoretical framework of linkage development, which is then discussed in the context of neglected development minerals. This paper argues that because of certain particularities of industrial minerals (in terms of scale, low-rent generation, technology and capital-intensity), the type of linkages that are likely to maximize the impact of those minerals on manufacturing and agricultural development are forward production linkages. Turning to empirical evidence, this paper reviews two cases of Development Mineral beneficiation as inputs for other sectors, which goes against the conventional wisdom that such minerals have a low impact on manufacturing and the rest of the economy. The first case is the Algerian Cevital Group using sand, dolomite and other industrial minerals as inputs for glass manufacturing as well as its further value-addition through window manufacturing. The second case study involves the activities of the OCP Group in the beneficiation of phosphates into fertilizers in Morocco and its use as inputs for agricultural development across the African region. In conclusion, this project sheds light on the often-neglected opportunities to harness mineral resources in Africa for domestic economic development.

Triboelectric separation has gained importance as a dry separator for mineral and coal beneficiation. The different grade components of coal powder can be classified, beneficiated, and segregated with the help of the triboelectric separator. A batch-mode triboelectric separator is being used in CSIR-Institute of Minerals & Materials Technology for separating pure coal particles from gangue quartz and kaolinite particles. The sticking of particles on the electrode plates forces the separator to be paused for cleaning the electrode plates. A moving belt over an electrode plate can prevent its direct contact with particles and also carries the particle down towards collection bins. The feasibility study of installing moving belts along with the optimum conditions for design and operating parameters were studied with the help of DEM simulations. The bi-modal frequency distributions of coal and quartz in collection bins ware observed. The rationale for observation of bi-modal distribution is attributed to the varying initial angles and velocities of the particles entering the active electric field region. The non-uniform probabilistic opportunities of the particles to attach with the respective belts resulted in two groups of particles; (a) particles attached to belt followed by their collection in the expected bins (b) particles with initial inclination opposite to the direction of external force and their collection in the bins on the other side. The second group of particles followed trajectories governed by external forces and got collected into the bins on the other side. The phenomena resulted in the bi-modal distribution of mass distribution.

The beneficiation of agricultural waste is a topical issue in the field of sustainable and renewable energy production. This review focuses on recent methods applied to extract silica and silicon (...

Cyanide is a known toxic chemical compound that has an adverse effect on living organisms. Nonetheless, it is one of the active reagents in industries such as mining, pharmaceutical, cosmetics, and food processing companies worldwide. The beneficiation of gold and other precious metals from ore generates great amount of cyanide-bearing contaminants, which is released into the environment. The abundance of cyanide contaminants from these industries have created public health concern since the inception of metal extraction from ore. There are strict regulations on the production, transportation, utilization, and disposal of cyanide-bearing contaminants worldwide. The conventional treatment of cyanide waste is either chemical or physical process. The use of these treatment processes has certain pitfalls like operational challenges, an increase in capital cost, and generation of secondary waste. A number of microorganisms have the potential to utilize cyanide as nitrogen and carbon source and transform it into ammonia and carbon dioxide. Biodetoxification might be efficiently, economically and environmentally safe to detoxify cyanide in contaminants and attractive alternative to conventional detoxification method like chemical or physical. This paper reviews the principles and methods of biodetoxification of cyanide contaminants found in the ecosystem.

Bentonite, especially Sodium (Na) Bentonite is a type of clay that is used as a basis for water-based drilling mud in the of oil and gas wells drilling throughout the world including Indonesia, bentonite used in Indonesia is still partially imported from abroad. Sodium Bentonite can be substituted with ordinary clay which is treated by beneficiation throught addition of Na2CO3. The area of Musi Rawas Utara (Muratara) Regency of South Sumatra Province contains clay reserves resulting from pyroclastic deposit which will be investigated as potential subtitutional materials of imported API Bentonite. Clay samples from 6 different locations were prepared by first looking for the best % swell of sample beneficiation combination from all over the 36 combinations through the free swell test, the results obtained that the 4% BWOC Na2CO3 combination gave the best % swell. From this, 24 samples were prepared for various measurements of mud properties using standard equipment and procedures following the API RP 13 B for water-based mud with drilling grade Na-bentonite (API Bentonite) as standard material. The test includes 7 properties which are divided into 16 measurement units namely density, rheology, filtration, solid and liquid content, sand content, pH and methylene blue capacity etc. The test results show that the Na2CO3 beneficiation is able to change ionically the characteristics of the clay, but from the aspect of the suitability of the value of each test parameter to the standard value shows that none of the samples has full compatibility, which is mean that Muratara clay technically cannot be used as a substituent material of API Bentonite.

A gas–solid fluidized bed using magnetite particles is an effective methodology for coal beneficiation in the field of dry coal cleaning. Broadening the size range of magnetite used in the bed decreases medium preparation cost. In this study, a tapered fluidized bed was used to investigate a magnetite particle size range of −0.5 + 0.074 mm. The results showed that a tapered fluidized bed effectively strengthens mixing of magnetite with a wide size range (−0.5 + 0.074 mm). The results of beneficiation experiments indicated that with increasing tapered angle, separation efficiency increased and then decreased. The highest separation efficiency was obtained at a tapered angle of 10°. The optimal results showed that the ash content of the concentrate decreased from 31.82% to 12.33% with a probable error of 0.11, which indicated that a tapered fluidized bed was efficient to improve fine coal beneficiation performance.

Direct reduction of low-grade iron ore pelleted with coal was investigated using a pilot-scale rotary kiln. The evolution of the iron minerals, the strength of the pellets, and the emission characteristics were measured. The results showed that the rotary kiln could be divided into three major functional zones: reduction of hematite to wustite occurred at 1023–1163 K; wustite transformed to fine metallic iron particles at 1163–1318 K; and metallic iron particles aggregated within 6.5 m of the outlet. The product had a metallization ratio of 92%. Pellet strength was maintained at 30–45 N within the first zone and no disintegration occurred. Aggregation of metallic iron particles within the final zone improved the strength to 465 N. The reduced sample was treated by grinding followed by magnetic separation. Of the total iron in the ore, 85.61% was recovered as iron powder (grade: 92.0 mass%). Use of this process could reduce CO2 emissions by approximately 10%.