Ore Beneficiation Processes Research Articles

Synthesis of sodium 1,3-propanebis(dithiocarbamate) and study of its flotation properties

Development and selection of a suitable reagent for efficient flotation is of great importance for ore beneficiation processes. Dithiocarbamates represent a class of organic compounds that are widely used as reagent-collectors in ore flotation. In this work, we conducted an analytical review of the methods currently used for obtaining this class of compounds and established the main method for obtaining dithiocarbamate salts to be the interaction of primary or secondary amines with carbon disulfide (CS2) in the presence of potassium or sodium hydroxide. The aim of the reviewed work was to synthesize sodium 1,3-propanebis(dithiocarbamate), as well as to study its flotation properties in the beneficiation of gold-bearing sulfide ores. A simple and effective method for sodium 1,3-propanebis(dithiocarbamate) synthesizing was proposed. Its structure was confirmed using physicochemical methods (infrared spectroscopy, 1H, 13C nuclear magnetic resonance spectroscopy). A set of studies found that the combined use of potassium butyl xanthate and sodium dialkyl dithiophosphate (BTF-1552) with sodium 1,3-propanebis(dithiocarbamate) led an increase in the efficiency of extraction of the target component of up to 81.63%, as well as an increase in its content in the concentrate of up to 7 g/t. In addition, the combination of sodium 1,3-propanebis(dithiocarbamate) with potassium butyl xanthate was shown to enable an extraction efficiency of 80.51%, as well as a valuable component content in the concentrate of up to 6.5 g/t with a low gold content in flotation tailings of 0.07 g/t. The proposed synthesis method and the results of flotation tests of gold-bearing ores are of interest for further research in the field of organic synthesis and practical application.

Occurrence, distribution and fate of iodine during phosphate ore beneficiation process

Numerous beneficiation techniques, such as washing, grinding, flotation, digesting, and calcination, are used to concentrate the minerals found in phosphate rocks, which include apatite, carbonatites, and silicates. Significant iodine levels are often found in phosphate ore minerals, which have a distinctive geochemical occurrence. However, the exact occurrence and distribution of iodine in these minerals are not yet thoroughly understood. A study was carried out to investigate the iodine's distribution, occurrence modes (phases), and release rate in Moroccan phosphate as it undergoes the beneficiation process. The samples underwent a multi-analytical approach combining mineralogical and chemical characterization using ICP-MS, ICP-OES, XRD, elements titration, and Pearson correlation analysis for interelement relationships. Calcination, digestion, and Heavy liquid separation is used to study the fate of iodine. The analysis indicates that iodine is primarily found in fluorapatite, with local concentrations ranging from 35 to 130 ppm. The most enriched grains/zones are associated with fluorapatite, enriched in P2O5, F-. in addition, iodine is positively correlated with its main components, including P2O5, F-, SO3, Na2O, CaO, and REEs. The flotation and heavy liquid separation process used for calcite and silicate removal is acting as an iodine and P2O5 concentrator, given that 99 % of iodine occurs in the apatite phase. However, it has been demonstrated that iodine can be released during the digestion of phosphate rock. Where the initial iodine content is distributed among phosphoric acid, PG, and the gaseous phase, constituting 35 %, 25 %, and 40 %, respectively. Furthermore, the calcination of phosphate rock between 800–1000 °C shows that total iodine is released with gases in I2 form, leading to an increase in the concentration of iodine in the surrounding area. In this regard, an integrated pyrometallurgical process has been proposed for the valorization of iodine as silver iodide. This process involves trapping gaseous iodine in an alkaline solution, followed by precipitation, thereby contributing to the overarching objectives of the circular economy and environmental protection.

Feasibility Study on the Use of Iron Ore Tailings as Fine Aggregate with Glass Fibre in Concrete

Concrete is the most widely used building material in the world, but its production has significant environmental consequences, including high carbon emissions and natural resource depletion. As a result, there is an increasing interest in the development of sustainable concrete technologies that reduce concrete’s environmental footprint while maintaining its performance and durability. Partially replacing fine aggregate with industrial waste is one such approach. It is a great practice for developing sustainable concrete that can help with environmental problems caused by the dumping of these waste materials at the same time maintaining the performance of concrete. It also provides economic and social benefits in addition to the environmental benefits. iron ore tailings is one such industrial waste that is the by-product of iron ore beneficiation process which has shown the potential for partial replacement of fine aggregate in concrete. In addition, glass fibre is added to improve the tensile property of concrete. A concrete mix of M20 grade were prepared by replacing fine aggregate with iron ore tailing at replacement level 15%, 25%, and 35% and the optimum replacement percentage was obtained. Further, glass fibre was added at the dosage of 0.5% by the weight of cement to the mix with optimised replacement of iron ore tailings and tests were conducted. This work also examines concrete’s physical, mechanical and durability properties with partial replacement of fine aggregate with iron ore tailings and glass fibre by conducting tests on strength and durability. Results obtained indicates incorporation of iron ore tailing with concrete reduces the workability of concrete, and the addition of glass fibre improved the compressive strength and split tensile strength. Durability tests show an increase in water absorption with the addition of iron ore tailings and a medium level of chloride penetration. The study showed the use of iron ore tailing as a sustainable alternative to fine aggregate in concrete.

Pool bio-oxidation and fitting analysis of low-grade arsenic-containing refractory gold ore

To overcome the limitations of geography, climate, and ore characteristics on the ore beneficiation process, bio-oxidation studies on low-grade arsenic-bearing refractory gold ore by pool leaching were carried out, as well as process fitting analysis. The gold particles are encapsulated by pyrite and arsenopyrite. After 60 days of bio-oxidation, the oxidation rates of arsenic, sulfur, and gold were 39%∼69%, 24%∼41%, and 49%∼83%, respectively. The inoculated Acidithiobacillus ferrooxidans, Ferroplasma acidiphilum, and Leptospirillum ferrodiazotrophum could all mediate the initial pyrite/arsenopyrite oxidation and the Fe2+ oxidation reaction, but only the former could mediate the subsequent sulfur compound oxidation. When compared to daily bacterial circulation and bacterial replacement every ten days, aeration improved the gold leaching rate by 14%∼22%. The Boltzmann model could fit both the arsenic and sulfur bio-oxidation, with model fit variances greater than 0.98. Based on the experimental and fitting results, the bio-oxidation cycle was determined to be 60 days, and the bio-oxidation mechanisms are summarized. This study has significant practical implications for the rational utilization of gold resources and provides theoretical and practical guidance for similar gold ores.

ЕКОНОМІКО-МАТЕМАТИЧНЕ МОДЕЛЮВАННЯ ДИНАМІКИ ЕНЕРГОСПОЖИВАННЯ ЗБАГАЧУВАЛЬНОЇ ФАБРИКИ

The purpose of the work is to establish the dependence of electricity costs on the dynamics of energy consumption from the dynamics of ore supply to the beneficiation plant bunker, namely from the loading period and its duration, and to develop, on the basis of the identified patterns of organizational, technical and economic measures to reduce the energy component of the cost of production of iron ore concentrate at the mining enrichment enterprises. Economic-mathematical methods were used to develop models of the formation of electricity costs on the dynamics of energy consumption, namely: the theory of impulse processes for the development of a model of ore supply to the bunker of the beneficiation factory; operational calculation methods, ore beneficiation theory and power supply theory for the development of a dynamic beneficiation process line model and power consumption model; methods of spectral analysis to identify the dynamic component of active power and electrical energy consumed by the ore beneficiation process; Cost analysis methods were used to calculate electricity costs; economic-mathematical modeling of energy consumption dynamics was performed by computer modeling using the Mathcad software package. An economic-mathematical model of the energy consumption dynamics of the enrichment factory was developed. The regularities of influence of ore loading parameters of beneficiation factory bunkers on the dynamics of the formation of electricity costs during the production of iron ore concentrate have been revealed. Mathematical dependencies of costs for the dynamic component of electrical energy on the time parameters of the process of loading ore into the hopper of the beneficiation factory, namely on the period and time of loading, were obtained. Organizational and economic measures have been developed to load the bunkers of the beneficiation factory, which ensure the saving of electricity. The regularities of influence of ore loading parameters of beneficiation factory bunkers on the dynamics of the formation of electricity costs during the production of iron ore concentrate have been revealed. The principles of building a system of financial incentives for operational and dispatching personnel for saving electricity based on the results of economic and mathematical modeling have been developed. For the first time, it wa s established that the energy component of the production cost of iron ore concentrate depends not only on the quantity and quality of ore, but also on the dynamic parameters of the process of loading ore into the bunkers of the beneficiation factory, while this established dependence has a non-linear nature on the period and time of loading. The proposed measures to save electricity due to the implementation of rational modes of loading bunkers of the beneficia-tion factory with ore can be used in the development of energy saving plans and programs and the development of job instructions for the dispatching staff of the ore beneficiation factory, which will allow to reduce the energy component of the production cost of iron ore concentrate. A system of financial incentives for operational dispatching staff of the beneficiation factory has been developed, which takes into account the saving of electrical energy due to the management of the ore loading of the bunkers of the beneficiation factory and the intensity of the staff’s work.

Thiol-Silylated Cellulose Nanocrystals as Selective Biodepressants in Froth Flotation.

The extraction of various minerals is commonly conducted through froth flotation, which is a versatile separation method in mineral processing. In froth flotation, depressants are employed to improve the flotation selectivity by modifying the wettability of the minerals and reducing their natural or induced floatability. However, the environmental impact of many current flotation chemicals poses a challenge to the sustainability and selectivity of the ore beneficiation processes. To mitigate this issue, cellulose, particularly nanocelluloses, has been explored as a potential alternative to promote sustainable mineral processing. This study focused on silylated cellulose nanocrystals (CNCs) as biodepressants for sulfide minerals in froth flotation. CNCs containing thiol silane groups or bifunctional CNCs containing both thiol and propyl silanes were synthesized using an aqueous silylation reaction, and their performance in the flotation of chalcopyrite and pyrite was investigated in the presence of a sodium isobutyl xanthate collector. The results showed that the modified CNCs exhibited preferential interaction between chalcopyrite, and the flotation recovery of chalcopyrite decreased from ∼76% to ∼24% in the presence of thiol-grafted CNCs at pH 6, while the pyrite recovery decreased only from ∼82% to ∼75%, indicating the efficient selectivity of thiol-silylated CNCs toward chalcopyrite depression.

EDEM and FLUENT Parameter Finding and Verification Study of Thickener Based on Genetic Neural Network

To improve the concentration performance of the concentrator in the iron ore beneficiation process for iron ore tailings, a coupled simulation analysis of the concentration process was conducted using the discrete element software EDEM (Engineering Discrete Element Method) and the finite element FLUENT software. The volume concentration at the bottom flow outlet of the concentrator was used as the evaluation index. The scraper rotation speed, feed rate, and feed concentration were considered as parameters. Response surface experiments were designed using the Box-Behnken module in Design Expert11 software, and numerical simulations were performed to obtain data. Based on the numerical simulation results, a prediction model was established using the backpropagation neural network (backpropagation neural network, BP-NN) and combined with the genetic algorithm (genetic algorithm, GA) for parameter optimization of the thickener’s concentration conditions. The results showed that with a scraper rotation speed of 9.7677 rpm, feed rate of 0.2037 m/s, and feed concentration of 6.5268%, the maximum outlet volume concentration reached approximately 62.00%. The predicted optimal working conditions were validated through physical tests and numerical simulations. The average outlet volume concentration in the physical tests was 60.712% (n = 10) (“n” is the number of experiments), with an error of only 2.077% compared to the predicted value. The middle outlet volume concentration in the numerical simulation experiments was 59.951% (n = 10), with an error of only 3.304% from the expected value. These results demonstrate the feasibility of using a genetic neural network for optimizing the EDEM–FLUENT simulation parameters of the thickener, providing valuable insights for the matching optimization of the thickener’s process parameters.

An Overview of Currently Applied Ferrochrome Production Processes and Their Waste Management Practices

Ferrochrome (FeCr) is the main source of virgin chromium (Cr) units used in modern-day chromium (Cr) containing alloys. The vast majority of produced Cr is used during the production of stainless steel, which owes its corrosion resistance mainly to the presence of Cr. In turn, stainless steel is mainly produced from Cr-containing scrap metal and FeCr, which is a relatively crude alloy between iron (Fe) and Cr. The production of FeCr is an energy and material-intensive process, and a relatively wide variety of by-products, typically classified as waste materials by the FeCr industry, are created during FeCr production. The type and extent of waste generation are dictated by the smelting route used and the management practices thereof employed by a specific smelter. In some cases, waste management of hazardous and non-hazardous materials may be classified as insufficient. Hazardous materials, such as hexavalent Cr, i.e., Cr(VI), -containing wastes, are only partially mitigated. Additionally, energy-containing wastes, such as carbon monoxide (CO)-rich off-gas, are typically discarded, and energy-invested materials, such as fine oxidative sintered chromite, are either stockpiled or sold as ordinary chromite. In cases where low-value containing wastes are generated, such as rejects from ore beneficiation processes, consistent and efficient processes are either difficult to employ or the return on investment of such processes is not economically viable. More so, the development of less carbon (C)-intensive (e.g., partial replacement of C reductants) and low-temperature pellet curing processes are currently not considered by the South African FeCr smelting industry. The reasoning for this is mainly due to increased operation costs (if improved waste management were to be implemented/higher cost reductants were used) and a lack of research initiatives. These reasons result in the stagnation of technologies. From an environmental point of view, smelting industries are pressured to reduce C emissions. An attractive approach for removing oxygen from the target metal oxides, and the mitigation of gaseous C, is by using hydrogen as a reductant. By doing so, water vapor is the only by-product. It is however expected that stable metal oxides, such as the Cr-oxide present in chromite, will be significantly more resistive to gaseous hydrogen-based reduction when compared to Fe-oxides. In this review, the various processes currently used by the South African FeCr industry are summarized in detail, and the waste materials per process step are identified. The limitations of current waste management regimes and possible alternative routes are discussed where applicable. Various management regimes are identified that could be improved, i.e., by utilizing the energy associated with CO-rich off-gas combustion, employing a low-temperature alternative chromite pelletization process, and considering the potential of hydrogen as a chromite reductant. These identified regimes are discussed in further detail, and alterative processes/approaches to waste management are proposed.

Stone Tools from Prehistoric Mining Sites in North Tyrol, Austria: Typology – Terminology – Material Properties

Mining archaeological field prospections and excavations conducted by the Research Center HiMAT at the University of Innsbruck yielded proof of extensive copper ore mining from the late Middle Bronze Age to the Early Iron Age (1300 - 700 BC) in the mining regions of Kitzbühel-Jochberg and Schwaz-Brixlegg in Northern Tyrol. This paper deals with stone tools collected at prehistoric mining sites and focusses on their typology, material properties and the problem of terminology. Petrographic analyses show a conscious selection of special stone materials for different applications. Typically, hard and tough metamorphic rocks collected from river gravel banks or glacial deposits of alpine valleys were used as raw materials for tool production. In general, well-rounded pebbles and boulders of amphibolite, garnet-amphibolite and eclogite were the preferred rock type used for percussion tools. According to the archaeological evidence, such stone tools were mostly used in the ore beneficiation process (crushing, to some extend also grinding) and have only rarely been found in connection with underground mining activities. For further beneficiation processes (grinding), other properties of the stone material such as abrasive capacity were required. In this context, boulders of orthogneiss/gneiss were the favoured rock material for netherstones (anvil stones and lower grindstones) and upper grindstones. The investigation of hafting modifications visible on stone tools shows that several hafting methods can be discussed, and that cords from plant fibres as well as straps of animal skin/leather could have been used for this purpose. Analysis of traces of wear provide information on the former function of the stone tools as well as on their practical application.

Pollution characteristics of soil heavy metals around two typical copper mining and beneficiation enterprises in Northwest China.

In order to investigate the situation of heavy metal pollution in the heavy metal industry in Gansu Province, a large copper mining province, two large and typical copper mining and beneficiation enterprises with differences in topographic features, climatic conditions, and soil types were selected as the target of this study based on similar ore types and beneficiation processes. Around these two enterprises, geochemical baselines of the six heavy metals were established, while the degree of local soil heavy metal pollution and potential hazards to humans were assessed based on statistical analysis, single-factor and multi-factor index analysis, and health risk evaluation models. In addition, Spearman's correlation analysis and hierarchical cluster analysis were used to explore the intrinsic association between each heavy metal in the two mining industries to reveal the pattern of soil heavy metal pollution in the copper mining and beneficiation industry and to propose targeted measures to improve and prevent soil heavy metal pollution. The results showed that the heavy metal pollution in the soil around Shengxi Mining Co., Ltd. of Subei County (SX enterprise) was higher than that around Yangba Copper Co., Ltd. of Gansu Province (YB enterprise), but the two enterprises had similar patterns of pollution, with an overall medium level of pollution. The carcinogenic and non-carcinogenic risks for children and adults were within acceptable limits for both enterprises. Besides, the correlation between the different heavy metals to similarity in their sources of contamination and the different degrees of association between the soil heavy metals of the two enterprises due to their environmental characteristics.

Influence of mechanical treatment and magnetic separation on the performance of iron ore tailings as supplementary cementitious material

Despite the great importance of iron mining in the Brazilian economy, significant volumes of tailings with high iron content are generated in the ore beneficiation process. Even with high crystallinity, studies show that the iron ore tailings (IOT) can be used as a supplementary cementitious material (SCM). In this context, this work analyzes the influence of primary (PMT) and secondary (SMT) mechanical treatment and magnetic separation (MS) on the performance of IOT as SCM. To this end, the performance of cementitious composites (pastes and mortars for structural purposes) produced with and without 15% cement replacement by IOT under different treatment conditions was evaluated. The feasibility of reprocessing the iron-rich waste material (IRW) from MS was analyzed. The results showed that, even with SMT, the tailings did not show pozzolanic activity. The tailings with MS and SMT influenced the heat of hydration of the pastes, due to the greater nucleation effect, compared to the other tailings. For this sample, higher compressive strength was achieved among the samples with IOT. The IRW, when submitted to a flotation process, produced a material that still has economic viability.

Review on development of low-grade scheelite recovery from molybdenum tailings in Luanchuan, China: A case study of Luoyang Yulu Mining Company

Luanchuan area is one of the regions with the largest scale of scheelite beneficiation and the largest output of scheelite concentrate in the world. After years of innovation and progress, the beneficiation technology of low-grade scheelite associated with molybdenum tailings in Luanchuan area is becoming more and more perfect. In this study, the development process of low-grade scheelite recycling technology in Luanchuan area was reviewed, including raw ore properties, beneficiation process, flotation equipment and flotation reagents. Meanwhile, taking Luoyang Yulu Mining Co., Ltd. as an example, the effects of various technical transformations such as the optimization of the beneficiation process, the column−machine combined process, and the high-efficiency flotation reagents were elucidated in detail. However, the recycling technology of low-grade scheelite of Luanchuan area is still possible to be improved. As a result, coupled with the latest research progress, the development direction of low-grade scheelite beneficiation in Luanchuan area was also prospected. It is of great significance to further improve the recovery efficiency of low-grade scheelite resources in Luanchuan area and this can provide technical reference for other scheelite plants.

CONTROLLING GRINDING PROCESS PARAMETERS USING CENTRAL COMPOSITE DESIGN TO REDUCE SLIMES IN PHOSPHATE ORE BENEFICIATION

Ultrafine particles resulting from the grinding operations of phosphate ore cause problems of air pollution, and of the beneficiation plants particularly, flotation cells and filtration units. Particles of less than 38 μm are one of the undesirable consequences of the phosphate ore beneficiation stage, where fine or ultrafine powder accounts for 10–30 percent of phosphate quantities and is regarded as a loss. Furthermore, maintaining additional amounts of phosphate by reducing these particles will provide several benefits, including minimizing the environmental implications of slime disposal and enhancing the economic impact of the phosphate ore beneficiation process. This paper aims to maximize the useful phosphate particles and reduce the slime instead of doing even more work with traditional techniques. This goal might be attained by increasing the percent of particles of the desired size of the phosphate (Target) during the grinding process by determining the optimal operational conditions, that will reduce the amount of slime. The central composite design (CCD) is used to identify the number of experiments to be evaluated and to create a predictive model to be used for determining the optimal operation parameters. As a result of the optimization process, a maximum Target of 87.6% was obtained at grinding conditions t (5.1 min), v (42.6%), s (81.2%), and c (50.7%). Where t, v, s, and c stand for grinding time, occupied volume of ball, rotational speed percent from critical speed (%) and solid concentration by volume (%) respectively.

Rock Fragmentation Evaluation towards Blast-To-Mill Concept of Blast Optimization in Hard Rock Mines

Traditional blast optimisation studies ensure efficient mining operation but ignore potential impact of blasting on primary crushing. The performance of the primary crusher is key to the ore beneficiation process. Optimisation studies conducted through the mining operations to the comminution circuit is vital to the mine-to-mill concepts in the mining industry. In this approach, an innovative approach to the assessment of in-situ blasting is proposed and evaluated. This approach focuses on the acceptability of rock fragments on the Run-of-Mine (ROM) pad as opposed to the pits. Fragmentation analysis was conducted in the pit and on the ROM pad. A correlation efficiency of 0.92 was realized between the measured rock fragments in the pit and that on the ROM pad. About 10% of the rock fragments in the pit were classified as boulders while about 30% of the same rock fragments deposited on the ROM pad were classified as boulders. However, about 30% of the rockpile on the ROM pad was estimated to be lower than the Close Side Setting (CSS) of the primary crusher. It is recommended that future research evaluates the energy consumption and its related cost at the primary crusher in comparison to in-pit fragmentation and mucking cost performance.

REE'lerin Belirlenmesine Yönelik Çeşitli Analitik Teknikler Üzerine Bir Derleme

Due to the transition from traditional energy sources to clean energy in recent years, it is stated that there will be a continuous increase in the need for REEs worldwide in the coming years owing to their especial physical and chemical properties. The principal sources of REEs are the minerals bastnazite, monazite, and xenotime, etc.. Rare earths have peculiar, unique properties and become essential in many high-tech applications. Therefore, the REEs is used for applications such as improvement of industrial. It is worth highlighting that the separation of rare earth can be both complex and challenging owing to similar properties which are shared to produce high quality and better quantity of REEs. In industrial production, complex ores containing rare earth elements are concentrated by physical ore beneficiation processes. For this, the processes proposed in this work possesses aguide on green chemistry, solvent extraction, membran filtration, adsorption of recovering REEs through stepwise extraction and enrichment technique. This review, attempts to provide notable information on the separation and purification efforts to date for the recovery of REEs.

Estimation of the mode I fracture toughness and evaluations on the strain behaviors of the compacted mine tailings from full-field displacement fields via digital image correlation

Ore beneficiation processes produce huge quantities of waste rock in the form of tailings. For dispersed remote artisanal mining sites that are unapproachable to strong construction and building materials, compacted MTs can be utilized an alternative to construct civilian buildings. The mechanical behaviors of compacted clay and adobe masonry were studied by numerous researchers; however, the understanding of the strain behavior and fracture properties was insufficient to illustrate compacted MTs due to differences in the material properties. Therefore, in this paper, the strain behavior and fracture properties of compacted MTs under mode I loading condition were explored. A series of semi-circular bending (SCB) tests were performed to examine the mode I fracture behavior of compacted MTs at different notch depths. Simultaneously, digital image correlation (DIC) technique was utilized to acquire the surface image sequence under mode I loading condition in order to characterize the strain behaviors. Williams series was introduced to measure the mode I fracture toughness in a full-field displacement field via DIC analysis. The mode I fracture toughness obtained by empirical equation, the Williams series, and the modified empirical equation considering plasticity in the notch tip were all comparatively examined in this paper. Moreover, the strain behaviors of the compacted MTs at different loading levels were explored. Finally, the size of the fracture process zone (FPZ) and crack tip opening displacement (CTOD) were quantified by using DIC. Results revealed that the mode I fracture toughness obtained from full-field displacement field and modified empirical equation analysis was larger than from the empirical equation.

Carbon dioxide sequestration by mines: implications for climate change

Anthropogenic activities contribute significantly to the increase in greenhouse gases in the atmosphere, leading to global warming and climate change. Emissions of carbon dioxide (CO2) during ore extraction and beneficiation processes are known to play a substantial role. However, mining waste and abandoned mines have the capacity to sequester CO2 from the atmosphere, which could be a sustainable solution to mitigate climate change. The present review is intended to facilitate an understanding of the factors affecting CO2 sequestration by mining waste and its feasibility at a global scale. The process of mineral carbonation, which itself generates CO2 and contributes to climate change, is a slow process, and pretreatment (mechanical, chemical and thermal) is required to enhance the reaction kinetics, but it increases the implementation cost. However, mineral carbonation is also a sustainable approach to achieve reclamation of mining sites and to immobilize heavy metals in leachate. Life cycle assessment studies have excluded mineral carbonation and include only environmental risks and impacts due to mines. Mining waste is generated in huge quantities, and its potential to sequester CO2 from the atmosphere should be encouraged for its application at an industrial scale. Further research is needed to explore the economic and technical feasibility of using mining waste to reduce atmospheric CO2 content at a global level.

Mineralogical Characterization Applied to Iron Ore Tailings from the Desliming Stage with Emphasis on Quantitative Electron Microscopy (Qem)

The search for alternatives that minimize the generation of tailings and enable their reuse, leads to characterization studies with the objective of a better understanding of the physical, chemical and mineralogical properties of iron ore tailings. The increase in demand for high-quality ore overlapping ore extraction with increasingly lower iron concentration levels, is part of the challenge of mineral exploitation. In view of the aforementioned needs, a more detailed characterization of the tailings contributes to the improvement of the mineral processing stage and the reuse of the generated tailings. To this end, an analysis of the characteristics of the tailings was carried out through physical, chemical and mineralogical characterization, with emphasis on quantitative electron microscopy - QEM. The tests revealed that the predominant phases are hematite and quartz and, to a lesser extent, goethite, gibbsite and kaolinite. As for the degree of release, hematite/magnetite has 88.13% of its particles totally free, 0.53% associated with quartz and 6.77% associated with goethite. The chemical composition is 32.29% Fe, 47.92% SiO2, 2.76% Al2O3, and 2.14% PPI. In this scenario, mineralogical characterization, as a main component of geometallurgy, makes it possible to propose alternatives that improve the ore beneficiation process and the reuse of tailings.

THERMAL AND ECONOMIC ANALYSIS OF LIME PRODUCTION

The ore beneficiation process uses little technology, but mining companies have high economic performance. As an energy source, firewood plays a fundamental role due to its simple storage, low cost, great availability of forests, and lack of processing. Thus, the present work aims to analyze the consumption of firewood as fuel and possible improvements in the process for the production of lime in terms of harnessing raw materials and costs. Calcium oxide is obtained from the thermal decomposition of calcium and magnesium carbonates obtained from dolomitic deposits of limestone (CaCO3 : CaMgCO3). After CaO extraction, it is subjected to a calcination process, removing carbon dioxide (CO2) in ovens that work at temperatures between 900 and 1200°C. The source of energy applied to the calcination furnaces in the analyzed area is wood. The wood has a calorific value between 2,250 and 2,700 Kcal/Kg, but the moisture content responsible for the thermal variation must be considered. The firewood burning process was carried out in a ravine type oven where the temperature at which operators are exposed to heat was evaluated. The results indicated that the cooking time dropped by 20% as the amount of wood is fed into the oven. This increase represents a significant gain in lime production, thus leading to a higher profit for the company.

REUSE RESIDUAL SAND CASTING FOR PRODUCTION OF CONCRETE BLOCKS

The ore beneficiation process uses little technology, but mining companies have high economic performance. As an energy source, firewood plays a fundamental role due to its simple storage, low cost, great availability of forests, and lack of processing. Thus, the present work aims to analyze the consumption of firewood as fuel and possible improvements in the process for the production of lime in terms of harnessing raw materials and costs. Calcium oxide is obtained from the thermal decomposition of calcium and magnesium carbonates obtained from dolomitic deposits of limestone (CaCO3 : CaMgCO3). After CaO extraction, it is subjected to a calcination process, removing carbon dioxide (CO2) in ovens that work at temperatures between 900 and 1200°C. The source of energy applied to the calcination furnaces in the analyzed area is wood. The wood has a calorific value between 2,250 and 2,700 Kcal/Kg, but the moisture content responsible for the thermal variation must be considered. The firewood burning process was carried out in a ravine type oven where the temperature at which operators are exposed to heat was evaluated. The results indicated that the cooking time dropped by 20% as the amount of wood is fed into the oven. This increase represents a significant gain in lime production, thus leading to a higher profit for the company.