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By Rogerio de Oliveira Baldoino

The sedimentary phosphate deposit of Bayovar is located in a very dry area of Peru (desert of Sechura) which is close to the Pacific coast. It consists of seven superposed layers (beds) which call for different strategy of concentration. The ore is composed predominantly by apatite (84% in weight basis) plus silicates (16%). In order to treat the ore from beds 1-5, a suitable standard mineral processing circuit (composed of scrubbing, screening, attrition and desliming) started its operation in 2010, yielding 3.9 Mt/y of concentrate assaying 30% of P2O5. To concentrate phosphate from beds 6-7, however, it is necessary to carry out further cationic reverse flotation of silicates, at neutral pH, to yield a concentrate, which meets market specification. The new process was developed in laboratory scale by a collaborative program conducted between Vale S.A. and the University of Sao Paulo-Brazil. A pilot plant has currently been running in order to confirm the very good results yielded in laboratory scale. The successful accomplishment of flotation in the current beneficiation flow sheet will enable a capacity expansion of 1.9 Mt/y of concentrate assaying 30% of P2O5. As water resources are very limited at Bayovar region, all the steps of concentration, including flotation, must be performed with seawater, which must be continuously recycled. This work addresses some relevant topics related to the use of seawater in the reverse cationic flotation of silicates: influence of temperature, water quality (ageing and chemical composition) and collector type (ether amine versus condensate). The results indicate that condensate amine works better than ether amine. If flotation is conducted with the former collector, the separation process is able to tolerate changes in temperature (25-40oC) and water quality caused by either evaporation or ageing. Keywords: phosphate, flotation, seawater, temperature, ageing, concentration, salt

Sep 1, 2012

By Ali Dehghani Ahmadabadi

Gravity separation technique is widely used in mineral beneficiation practices for its low cost, ease of operation, and eco-friendly nature. The most commonly used gravity methods for beneficiation of iron ores are shaking table, jig and spiral methods which aren't very effective for iron mineral fines. Multi-Gravity Separator (MGS) is suitable for the treatment of fines with a maximum particle size of approximately 500 µm. This study was performed on a low-grade haematite iron ore from Chadormalutailing dams. Detailed mineralogical, physical and chemical characteristics of a goethiticlateritic iron ore showed that the sample contained porous and friable oxides and hydroxides of iron. The ore sample had a feed grade of 35% Fe, 1.1% FeO, 15.5% SiO2 and 8.5% Al2O3. Haematite and goethite are the main iron-bearing minerals while quartzite and kaolinite are the major gangue mineral constituents. In this paper, the statistical evaluation and optimization of grade and recovery using a factorial design of experiment (DOE) method has been carried out for Chadormalulow grade ultra-fine haematite tailings with MGS. The input process parameters considered are drum speed, tilt angle, wash water flow rate and pulp density. The results show considerable improvements in both the quality characteristics such as grade and recovery with statistical evaluation and optimization, compared to the initial value of grade and recovery. Keywords: multi-gravity separator, mgs, statistical evaluation, optimization, haematite

Sep 1, 2012

By N. Gurulaxmi Srikakulapu

The demand for high-grade iron ore has increased the importance of beneficiation of low-grade iron ores. The captive mines of Tata Steel Limited, India has reserves of Banded Haematite Jasper (BHJ) ore assayed 40% Fe, 40% SiO2 and <1% Al2O3. QEMSCAN study has revealed haematite and quartz as a major iron bearing and gangue mineral phases respectively. Liberation characteristics have showed 80% liberation can be obtained at particle size below 10µm. In the present study, reverse cationic froth flotation of BHJ using ether diamines is explored in Denver-D12 flotation cell. Polynomial response surface regression equation coupled with six-factor Box-Behnken design of experiments is used to generate the correlation between process separation efficiency and flotation parameters. Flotation studies of BHJ indicated that concentrate of 62% Fe can be achieved with 62% Fe recovery from Jig concentrate at optimum conditions. The obtained product can blend with pellet fines to feed in blast furnace. Keywords: banded haematite jasper, flotation, box-behnken design, response surface methodology

Sep 1, 2012

The ore studied occurred in the Three Rivers area in China and was a silver-lead-zinc complex ore containing 400.52 g/t silver, 4.77 % lead and 3.47 % zinc. Silver, lead and zinc were the major valuable elements in the ore and copper, cadmium and tin were the associated elements to be comprehensively recovered, whereas arsenic was the harmful element. The element silver occurred mainly in freibergite with small proportion in dyscrasite and other silver minerals. The carrier minerals for silver were mainly galena and oxidized lead minerals and then sphalerite, arsenopyrite and pyrite. The ore contained numerous minerals with complex mosaic texture and the lead and zinc minerals enclosed each other multiply, which made the separation of the minerals in the ore very difficult. Experimental investigation on the beneficiation of the ore indicated that with flotation separation process it was very hard to obtain single lead concentrate or single zinc concentrate that would meet the requirement of market. In the meantime, during the separation process of lead and zinc, silver tended to be dispersed, resulting in a low recovery of silver. Therefore, a rational utilization technique for the ore should be a combined process of bulk flotation to reduce arsenic? sulphating roasting of silver-lead-zinc bulk concentrate-leaching with diluted sulphuric acid to separate silver, lead and zinc. With this process quality lead concentrate containing silver and high grade zinc product and silver product could be obtained. The recovery of silver, lead and zinc in flotation was 85.10%, 84.48% and 82.48%, respectively. The total recovery of silver, lead and zinc in chemical processing was 97.07%(sum of recovery of silver ingot and lead concentrate), 99.61% and 90.93%, respectively.

Jan 1, 2014

By Heramb M. Bal

This paper will underpin the future development of intellectuals having greater understanding of patent law and legislation, IP rights, and innovation. To understand this idea, I present a case study of China?s progress in the last 31 years in the rare earth research, innovation, and simultaneously patents area. Rare earth elements (REE) are at the centre of high technology and are the next wave of world innovation. Much of modern society depends on rare earth elements through their use in computers, lasers, telecommunications, iPods, medical technology, military applications, and so on (Long et al, 2010). The rare earth research, a large research body is being provided by Chinese sources. China devoted three or four university centers to the study of rare earths (Lifton, 2009). These measures are all designed to keep China at the forefront of REE production, materials, technology, and innovation. As a result in the last fifteen years there has been a shift from a US-dominated REE industry patents to Chinese patents. The world must identify strategic areas of rare earth innovation and provide funding to firms and universities that conduct such research. Not only research and innovation is vital but filing patents and preserving IP rights for research and innovation is even more important. We (rest of the world) need a comprehensive strategy to guide the development of patent and IP rights for research and innovation. To achieve this, the development of intellectuals with superior knowledge of patents and IP rights are the future need of minerals industry. Keywords: innovation, rare earth, patent, IP rights

Sep 1, 2012

By Sergey Ulianov, Arkady Senchenko, Alexey Shvets, Arkady Bakotin

"This paper contains description of research results of technology development for copper recovery from weathered tails of iron processing plant. The predominant host mineral that contains valuable component is chalcopyrite occurring in its free form and in associations with ore and rock-forming minerals. Copper grade is 0.26-0.30%. Emulsion inclusions of chalcopyrite in pyrite and sphalerite were noted. Major problem is low copper recovery (30-35%) by flotation. When studying chalcopyrite in primary concentrate it was determined that the surfaces of many chalcopyrite grains are covered with oxide films which prevented collector attachment onto them. Second issue was deep association of chalcopyrite with pyrite and sphalerite. Sulfidizing reagent addition did not help to reach the required level of copper recovery to concentrate. In the result of research performed the technological flowsheet was developed including preliminary treatment of head material in a special unit aiming at oxide films removal, followed by copper rougher flotation on head size tails, crude concentrate regrinding and a number of cleaner flotation operations. After the treatment of weathered tails according to the flowsheet developed, copper recovery to flotation concentrate became 71.53%, at 23.46% copper grade. The suggested technology allows one to solve the issue with treatment of technology-related copper-containing stockpile material, as well as to include the ores where copper is represented by sulfide minerals covered with oxide films into processing."

Jan 1, 2014

By Jorge Misle, Daniel Silva

"This paper addresses the need for advanced control technologies and strategies in the mining industry, its potential and actual impact on mining processes and the best practices for their implementation, operation, and long term sustainability. It is well known that advanced process control (APC) can be a very good source for incremental process improvement for the mining industry, yielding to higher production rates or helping maintain consistent production rates despite ore changes. The application and integration of new technology, process knowledge and innovation are key elements in building such a supporting structure. More specifically, and this cannot be emphasized enough, the correct application and assembly of control tools, the in-time presentation of key data to decision makers and the development of relevant statistics and KPI’s (key performance indicators) can and will make a difference not only in terms of production, but also in plant stability, availability and production costs. In deploying such ideas and aiming at the long-term goal of "Operational Excellence", Minera Los Pelambres (MLP) has developed a number of successful control strategies, best practices and technologies, which are not only the application of state-of-the-art automation and computing tools, but rather the assembly of the above presented structuring factors. This work discusses some of the key tools and ideas implemented for SAG & Ball milling and Flotation areas, their performance results and the roadmap taken for the integration of process knowledge and control tools. Also, cases studies are presented and discussed further to not only show the main areas of improvement, but also to highlight the benefits of such strategy that for the most part, deviate from the traditional mining industry control approach. Also, a word is given on the need for innovating in the design of control strategies and leveraging best practices and process knowledge that ultimately, will contribute to long-term reliable operations, improved mineral processing and, although unmeasured, lead to a superior overall performance and productivity of all mining personnel involved."

Jan 1, 2014

By T. Khonthu

The purpose of this investigation was to evaluate the relationship between different milling procedures, viz. a ball mill and an IsaMill respectively, and the flotation performance of the different mill products. Two ores were used, viz. a base metal sulphide (BMS) and a platinum group mineral (PGM) UG2 ore. Flotation was used as a diagnostic to investigate whether the different milling procedures may have different effects of the floatability of the particles. The present study is part of a research programme investigating this question using a wide range of comminutiondevices and procedures. Similar particle size fractions from the different milling procedures were used in the flotation tests. The particles were characterized in terms of particle size distribution, morphology (using scanning electron microscopy and image analysis software) and rheology tests. The results have shown that in general when comparing similar feeds to flotation in terms of equivalent particle size distributions as indicated by the d80 value, the ball mill generally yielded better recoveries and grades in the case of the BMS and lower chromite recoveries in the case of the UG2 ore compared to the IsaMill. No significant differences were observed in the morphological or rheological characteristics of the particles subjected to the different milling procedures. Although the results appear to indicate that IsaMilling is less advantageous than ball milling in terms of the flotation performance for the two ores studied it should be emphasized that these results do not take into account the relative advantage which IsaMilling has over ball milling in terms of direct and indirect energy consumption and GHG emissions nor, most importantly, does it consider the platinum group element recoveries in the case of the UG2 which may have increased significantly as a result of the finer grind which the IsaMill produces after 4 passes compared to the ball mill after 64 min. Such results which will be reported is due course may show that the greater liberation expected after IsaMilling of the PGMs outweighs any disadvantages indicated in this study.

Sep 1, 2012

By Dongyun Liang

Process mineralogy focuses on the chemical components and mineral composition of ore, dissemination size of valuable minerals, the occurrence of valuable and detrimental elements as well as the behavior of each mineral in the process. Through determining process mineralogy parameters and analyzing the characteristics of minerals, the results of process mineralogy study can provide mineralogy data for making a reasonable mineral processing technology program and optimizing the process. A detailed process mineralogy study is carried out for a complex rare metal ore in this paper and the results show that niobium mainly exists in the form of ferrocolumbite as well as nioboaeschynite and zirconium primarily occurs as zircon. The valuable minerals including Th-nioboaeschynite, ferrocolumbite, zircon, etc. have the characteristics of fine dissemination size, wide size range, complex chemical composition and variable physical properties, which mean it is a refractory ore. According to the results of mineral composition of ore, chemical composition of minerals, dissemination size of minerals, magnetism ranges of minerals and the distribution of niobium and zirconium, the process of ?desliming-Nb-Zr bulk flotation? is designed for this ore and the niobium-zirconium bulk rough concentrate with the grade of Nb2O5 9.43%, ZrO2 24.95%, Ta2O5 0.36% and the recovery of Nb2O5 77.66%, ZrO2 76.70%, Ta2O5 75.13% to crude ore can be obtained in the whole process closed-circuit test.

Sep 1, 2012

By D. Endara, E. De la Torre, S. Echeverria

"The study was conducted with the sulfide mineral from the province of Zamora Chinchipe. It was characterized physical, chemical and mineralogical, obtaining between its main results a copper concentration of head ore of 0,58 %. The mineral was homogenized and taken to direct closed circuit: rollers mill - vibratory sieve (mesh # 16). Flotation was carried out in two stages: the collective and selective where in each one were performed 6 water recirculation as suggested by the technique used to relate information of a batch flotation to a continuous circuit called cyclic flotation tests (LCT). In the collective flotation (bulk) 2 Kg of mineral were grinded with 10 Kg of balls for 30 minutes and 62.5% of solids, the pulp was taken to the flotation process with solids percentages of 33.3% and pH 7, it was conditioned with 45 g / t of KAX 1%, 50 g/t of Aerofloat 208 and 20 g /t of Pine oil. The concentrate and tailings bulk obtained were filtered separately for the recovery of water and it was recirculated to the next grinding of 2kg mineral. In the selective flotation 1Kg of bulk concentrate was carried to regrind for 40 min, 62.5% percent of solids, 10 g of lime and 5 g of tannin FLOATAN T5, the pulp was taken to the roughing-collection-refining flotation circuit controlling the pH between 10.5 and 11 where conditioning (60 g/t of Aerofloat 208 and 30 g/t of Pine oil) and adding lime to the circuit and FLOATAN according to the procedure. The four fractions obtained from the circuit were filtered; the water was recirculated to the regrind process of the bulk concentrate. In the collective flotation process tends to stability in the fourth recirculating water to obtain a copper content of 4.5% and a recovery of 87%, recirculated water represents 69.8% of all water used in the 6 recycles. In the selective flotation circuit the fifth recirculating of water is the optimal where obtaining a copper content of 13% and a recovery of 72%, recirculated water in the selective flotation circuit represents 95% of the total water used in the 6 recycles."

Jan 1, 2018

By Z. He

Based on full investigation of the characteristic of sphalerite in the residue obtained from cyanidation leaching process and the study of the mechanism of the interaction between flotation reagents and sphalerite with the aid of electrochemical analysis, the reagent named YO was developed for eliminating the depression effect of CN- on sphalerite and reducing the dosage of CuSO4. The achievements have been used in commercial production for the treatment of the cyanidation residue to recover the zinc minerals, obtaining a zinc concentrate with grade of 56.49% Zn and recovery of 86.63% Zn.

Jan 1, 2014

Domestic production of pyrite cinder reached 15.95 million tons in 2006. The pyrite cinder used in cement industry accounts for about 30% production. The remaining 70%, 11.17 million tons, was thrown away as waste, which brought serious environmental and resource problems. A new technology of composite pellet reduction-roasting and magnetic-separation (CPRM) has been developed to utilize pyrite cinder. Pyrite cinder sample, containing 45.56% Fe, 0.19% Cu and 1.45% S, was pelletized with addition of 5% composite agent in balling disc. Green balls after drying were reduced at 700~800 ? for 20min with 300kg/t pulverized coal injection in rotary kiln. After two stages of ball-grinding and four stages of magnetic separation, high grade magnetite concentrate with 66.23% Fe was produced, meanwhile impurities Cu and S was decreased to 0.048% and 0.053%, respectively. And iron recovery of 73.32%, desulphurization of 96.34% and decoppering degree of 74.73% were achieved. Key technique is that composite agent can accelerate reduction of Fe2O3 and transfer copper and sulphur into water-soluble inorganic salts, which can be removed during wet magnetic concentration. This new technology can be used to fully utilize pyrite cinder and produce high quality magnetite concentrates as feed for steel industry, which will help tackle the pollution problem of pyrite cinder and extend iron-bearing raw material sourcing for Chinese steel industry.

Jan 1, 2014

By C. B. Yu

The ore comprise of chalcopyrite, valleriite, pyrite, pyrrhotite and so on. Serpentine and talc are chief gangues. Copper phase of the tail shows that mostly valleriite be losed in tail, 70% mineral of copper is valleriite in tail, so severity reduce the recovery of copper. The traditional flow-sheet in acidity mine pulp to flotat the valleriite, but copper-sulphur separated in high alkaline pulp, so the valleriite be losed else. Explores the characters of the valleriite?s surface, studys on the flow-sheet of flotat valleriite and copper-sulphur separated. In neutral mine pulp, adopt of cationic collector to flotat valleriite, adopt of hyposulphite to depressant pyrite in low alkaline pulp can advance the recovery of copper to 5.06%.

Jan 1, 2014

The objective of the paper is to develop a material balance calculation procedure for a production unit involving two plants separated by a pipeline. The case study is taken from the oil sands industry. The raw sands are first mixed with water in a conditioning plant, then transported through a pipeline to an oil extraction plant. The combination of pipeline dimensions and nominal throughput creates a significant variable time lag between the two plants. As usual, mass balance calculations required for the evaluation of plant performance indicators, such as bitumen recovery, are inaccurate due to measurement errors. In addition, in the present case study, the time lag of the pipe creates an additional source of uncertainty, which may lead to misinterpretations and wrong decisions. Raw data are usually reconciled through steady-state mass balancing, to correct for measurement errors. However, because of the significant pipeline dynamic lag, standard steady-state daily mass balance may fail at giving an appropriate picture of the operations. The proposed solution to the data reconciliation problem includes the use of a pipeline plug-flow model in the mass balance calculation. To fulfil the industrial constraint that current data reconciliation must not modify past reconciled values, while still satisfying dynamic constraints, a daily one-step method, i.e. a unitary filter-ing horizon, is recommended. The method is illustrated with simulation data, and the results com-pared to those of standard data reconciliation methods.

Jan 1, 2014

By P. Altinkaya, O. Celep, H. Deveci, E. Y. Yazici

"Copper-bearing gold ores have proved difficult to treat in conventional cyanide leaching process owing to prohibitively high consumption of cyanide by readily soluble copper minerals interfering with gold extraction. Cyanide leaching of gold from copper-rich ores can be improved by intensive cyanidation or application of physical and chemical pre-treatment methods (e.g., ultra-fine grinding, roasting and leaching). In this study, nitric acid leaching of a copper-bearing pyritic concentrate (0.3% Cu, 62 g/t Au and 110 g/t Ag) as pre-treatment prior to cyanidation was investigated. The mineralogical analysis of the concentrate has revealed that it is composed of mainly quartz (25%), pyrite (32.7%), sphalerite (5.37 %), galena (2.12 wt %) and anglesite (1.13 %). Arsenopyrite, chalcopyrite, covellite and bournonite were also detected as minor phases present. Previous studies carried out by the authors showed that direct cyanidation (1.5 g/L NaCN) of the as-received concentrate (d80: 80 µm) produced low gold (45% Au) and silver (46% Ag) extractions. Nitric acid pretreatment of the as-received concentrate was performed for 5 hours at 1-5 M HNO3 and 80oC. In these tests, 65% Cu/Pb and 94% Zn were leached. The nitric acid pre-treatment improved the extraction of gold and silver in subsequent cyanide leaching (1.5 g/L NaCN) to 82% Au and 87.5% Ag with a concomitant decrease (up to 54%) in cyanide consumption. It can be inferred from these findings that the removal of copper from the concentrate and the liberation of the occluded gold by nitric acid leaching as pretreatments can be appropriately employed for the treatment of the copper-bearing pyritic concentrate with high gold/silver content. INTRODUCTION Refractory ores are often characterized by their low amenability to cyanide leaching resulting low (often <80%) Au/Ag extractions (Bhappu, 1990; Celep et al., 2009; Marsden and House, 2006). One of the most common causes of refractoriness is the physical or chemical encapsulation of submicroscopic or fine-grained gold in sulphide minerals such as arsenopyrite and pyrite (La Brooy et al., 1994; Vaughan, 2004). To render refractory gold ores/concentrates amenable to cyanide leaching, the decomposition of sulphide minerals within a pre-treatment process to expose the encapsulated gold grains to the action of cyanide is required. In this regard, roasting, pressure oxidation and biooxidation are commercially used processes for pretreatment of arsenopyrite/pyrite gold ores/concentrates ahead of cyanide leaching (La Brooy et al., 1994). Presence of cyanide-soluble copper minerals in the ore leads to low gold recoveries and high cyanide consumptions under conventional cyanide leaching conditions. High cyanide concentrations (CN:Cu>4) should be employed to achieve high gold recoveries from copper-rich gold ores/concentrates. This may require recovery of cyanide from effluents. In this regard, SART Process (sulphidisation-acidification-recycling-thickening) employed industrially for recovery of cyanide and copper as a by-product. This process simply relies on the addition of sulphide (as Na2S, NaSH or H2S) to the leach solution prior to the acidification to pH 4-5. This results in the precipitation of copper as Cu2S and occurrence of free cyanide which is recycled to the leaching circuit after S/L separation (Dai et al., 2012)."

Jan 1, 2018

By N. I. Tyushkova

This is a brief survey of the technological solutions for deep cleaning of baddeleyite?s concen-trate. Baddeleyite is part of kamaphorite of composite apatite-magnetite ore in alkaline-ultrabasic mountain range of Kola Peninsula. Baddeleyite?s concentrate, which is being produced by Kovdorsky GOK (ore mining and processing enterprise) contains 97.5%~98.5% (Zr?2 + ?f?2) and also scandium oxide (0.05%). It is usually used without any chemical processing. World demand for zirconium oxide is constantly on the rise. Its consumption grows in ceramic industry and in high-tech spheres. That?s why the demand for its purity is very important nowadays (additional cleaning from phosphorus, silicon, iron, aluminium). The mechanism and kinetics of interaction of activated bad-deleyite with sulphuric acid has been studied as well. While applying method of mathematical mod-eling it was confirmed that the mechanical activation is effective for the intensification of sulphation process of baddeleyite?s concentrate with the aim of purifying it from dirt. The use of the calculated optimal regimes allows to reduce such technological operation factors as: temperature, the du-ration of process, the sulphuric acid consumption. It also allows to determine the conditions of anticipatory abstraction of scandium and main dirt in solution in comparison with zirconium oxide.

Jan 1, 2014

By S. J. Dai

The cadmium and cyanide are main poisonous components in cyanide electroplating cadmium waste water of an electroplating plant in Shenyang. The content of cadmium is about 26 mg/L and the content of cyanide is about 11.782 mg/L in this waste water. The main form of cadmium and cyanide are ions which are Cd2+and CN?. Because the cadmium and cyanide exceeded the standard seriously, the waste water must be disposed before it discharges. The microbiological method of treating heavy metals in wastewater has many advantages. For example, it has a fast adsorption velocity, high processing efficiency, wide range of pH and temperature, few invest, low running cost, no the second pollution and so on. At the same time, the CN? could be degradated by some microbiology. The physical nature, the chemical nature of Bacillus mucilaginosus, the adsorbing condition and adsorbing regular of Bacillus mucilaginosus to cadmium in the wastewater are studied by using Bacillus mucilaginosus as adsorbent removing cadmium from electroplating wastewater. The experimental results show that the adsorbing rate of cadmium is over 92%, under the room temperature(about 25?), stiring revolution in adsorption being 800 r/min for 30 min, pH being 5 , the bacteria being cultured after 5d with the biomass of Bacillus mucilaginosus 40g/L (wet weight). The mechanism in biosorption process of Bacillus mucilaginosus to cadmium is analyzed and discussed by TEM , Zeta potential,and infrared spectroscopy analysis. The results showed, the chemical involving is main adsorbing form, while electrostatic attraction, ions exchange, hydrogen bonding and Van Der Waals force are concerned cooperatively. ?NH2 ?, ?C=O?, ?C=O?NH?CH2, ?CH3, ?OH are main adsorbing groups. At the same time, the floatablity of removing cyanide by Bacillus mucilaginosus is explored.

Jan 1, 2014

By ?. S. Potokin

"In general the electric pulse treatment is composed from two processes – electric pulse grinding and electric explosive (electric discharging) activation. The electric pulse grinding with the effect of selective destruction refers to a major slag fraction, more that 2-5 mm, when a one can see a physical prerequisites for electrical breakdown of the slag particles. The electric pulse treatment of slag is considered as an additional operation in the technological scheme extraction of non-ferrous metals from copper smelting slags in addition with mechanical grinding, flotation enrichment and acid leaching. Studies of the reprocessability of pelletized slag have shown the possibility of higher extracting non-ferrous metals via flotation after electric pulse disintegration (EPD) treatment. By using EPD of slag pellets, it is possible to increase the non-ferrous metal yield to concentrate by 18-24%.INTRODUCTION The use of the explosive effect of the plasma discharge channel at electrical breakdown of a solid at a pulsed high voltage is the physical basis of the electric pulse method of destruction of geomaterials (Vorobiev et al., 1971; Andres, 1995; Semkin et al., 1995). The flowing of a pulsed current in the discharge channel is accompanied by a sharp increasing of plasma’s temperature and pressure, leading to a supersonic expanding of the discharge channel, the formation in the solid of intensive mechanical tension field, spreading of cracks, and eventually, to the destruction of the solid. Fragmentation and grinding of ore and mineral aggregates by electric pulse method due to a number of specific physical mechanisms of power load and crack formation, belonging only to this method, is different by high selectivity of destruction. This ensures better liberation of grains of individual minerals and their better preservation from destruction and less formation of a slurry output. These features creates the prerequisites for a more complete extraction of a useful mineral in the concentrate during ore dressing, to improve the quality of concentrate. In contradistinction to mechanical methods, electric pulse technology does not contaminate the product with instrumental metal, material of lining and grinding bodies. The possibility simply and in a wide range to change the dynamic load character allows to regulate the granulometric composition of the product of grinding, to obtain a narrower class of product size than is possible with mechanical grinding. The product of electric pulse grinding is characterized by less roundness and large specific surface area of grains due to the trait, that a new surface is formed in the process of splitting during the expanding of cracks. The degradation product has increased sorption and reactivity in chemical reactions. Liberation of the mineral inclusions particle better corresponds to their initial natural state in the rock and this is the great importance for the study of mineral raw materials."

Jan 1, 2018

This investigation addressed two products from Samarco?s desliming circuit, namely underflow of cleaning cyclones and underflow of desliming cyclones. The roughing cyclones receive the product of the grinding circuit. The underflow of the roughing cyclones feeds the cleaning cyclones and the overflow feeds the desliming cyclones. The underflows of cleaning and roughing cyclones are combined to constitute the feed of the flotation circuit. These fractions were characterized and a new process route was proposed. The size distributions of the two fractions are quite different. The desliming cyclones underflow presents higher amount of material passing 37 µm and of ultrafines as compared with the cleaning cyclones underflow. Laboratory scale flotation tests were performed in a mechanical machine aiming at comparing the performances of these products in the presence of the reagents employed in the concentrator. Pi-lot scale column flotation yielded enhanced iron recoveries for both products in comparison with those achieved in laboratory mechanical cells, without impairing the concentrate quality. The in-crease in recovery was more significant in the case of the cleaning cyclones underflow. These results suggest the use of columns in the flotation of this product aiming at increasing the overall iron recovery. Nevertheless the results also showed that the use of columns to float the cleaning cyclones underflow should also be taken into consideration. Despite the fact that this product requires a longer residence time in order that the required silica content in the concentrate is achieved, the indication is that higher levels of iron recoveries might be reached. The conclusion is that, due to the different behaviors of the two products, they should be processed in distinct circuits to maximize the iron recovery.

Jan 1, 2014

By R. Sakthivel

Blue dust is a high grade soft haematite material containing 96.14% Fe2O3 transformed into magnetite (Fe3O4), when it is subjected to planetary ball milling in the presence of iron powder as reducing reagent. X-ray diffraction (XRD), Field emission scanning electron microscope (FESEM) and Laser particle size analyser have been employed to characterize various samples collected at various milling times to know the phase evolution, particle size distribution and morphology of particles. X-ray diffraction studies reveal the formation of magnetite phase at the optimum milling time of 40 hours. Vibrating sample magnetometry (VSM) study demonstrates, that sample obtained at 40 hours of milling time exhibits saturation magnetisation of 14.757 emu/g whereas the starting material used in this study shows only 1.0425 emu/g. Keywords: Blue dust, reaction milling, magnetite, saturation magnetization

Sep 1, 2012