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By Ataollah Nosrati

Agglomeration of fine mineral particles is an important step in heap leaching processes employed for a cost-effective hydrometallurgical extraction of value metals from low-grade ores. In this study, the effect of acidic binder composition and feed ore particle size on binder dosage requirement and isothermal, batch agglomeration behavior of siliceous goethite nickel laterite has been investigated. Agglomeration tests performed with tap water and 30, 44 and 98% w/w H2SO4 solutions as binders revealed the key role of binder formulation in controlling ore particle wettability, nucleation and granule growth behavior. Both lower binder acid content and higher dosage led to greater wetting, nucleation and granule growth rates. Variation of feed ore fine/coarse particles? mass ratio dramatically impacted on binder dosage requirement for effective particle wetting, nucleation, and growth agglomeration behavior. Increasing fine (-150 µm) fraction mass content in a -2 mm feed ore, led to higher binder dosage requirement and enhanced nucleation, however the overall agglomeration rate/granule size growth decreased. In contrast, the presence of coarse (5 ? 15 mm) particles in feed ore led to (i) lower binder dosage requirement, (ii) enhanced initial agglomerate size growth rate, and (iii) reduced coalescence. For dry agglomerates of similar sizes, competent coarser feed particles led to remarkably higher compressive strength than did finer feed particles. Microstructure analyses indicated that the granules containing coarser particles exhibited a distinctive, competent core/shell (fines) structure which led to their structural reinforcement. The appropriation of the findings for optimizing agglomeration behavior for enhanced heap leaching of complex, low grade laterite ores are discussed in this context.

Sep 1, 2012

By Polezhaev S. Yu, I. V. Ukraintsev, Boduen A. Ya, Saburbayeva L. Yu

"Comparison studies of different technologies are performed when selecting optimum option for gold ore and concentrate processing. Methods of ultrafine grinding, oxidizing roasting, bacterial leaching and pressure oxidation are used to extract gold from refractory ores and concentrates. Refractory gold flotation concentrate produced from pyrite-arsenopyrite ores of Bestobe deposit is a case study in this paper. The results of the experimental tests of the direct leaching of flotation concentrate and pre-oxidation products using different methods (oxidizing roasting cinder, pressure oxidation and bacterial leaching cakes) are the following: - cyanidation of original flotation concentrate provides recovery of Au at 46.6 %; - oxidizing roasting increases gold recovery from 46.6 % to 85 %; - BIOX increases gold recovery up to 86 %; - preliminary pressure oxidation of flotation concentrate ensures steadily high Au extraction in the follow-up cyanidation at 94.9-96.5 %. Pressure oxidation and bio-oxidation has changed dramatically the strategy of refractory gold ore processing. These solutions provided for development of ore deposits that considered earlier non-commercial. However, refractory ore processing has a complex character in terms of developing process flowsheet and requires large amount of studies to be performed for each new project. Gold extraction is the basic but not the only criteria to technology selection for gold ore and concentrate processing. Opex and capex, ore reserves, regional geography, developed infrastructure and skill personnel should be considered. Process studies and feasibility study of the developed technology shall be provided for each specific gold ore deposit. INTRODUCTION Due to changes in available feedstock and depletion of easy-to-process ores, refractory ores containing finely disseminated gold and silver in sulphides (primarily, in pyrites and arsenopyrites) are more and more involved into processing. Experts say that such ores amount above 40 % of the world’s gold reserves. Conventional technologies of gold extraction from refractory ores include flotation, roasting and cinder cyanidation (Fraser etal., 1991). However, today’s best available practice for refractory gold ore processing are bacterial (BIOX) and pressure (POX) oxidation."

Jan 1, 2018

By Z. S. Abisheva

Results of the study targeted to development of universal acidic-extraction-precipitation technology for gallium recovery from the sublimates are presented in the paper. This will let to utilize a new non-traditional source for gallium production. Phase composition of gallium containing dust was studied. Forms of gallium in the sublimates were determined. The main form is Ga2O3, however, GaP form is also present in the cottrel dust and Na5Ga3F14 form is present in the dust of aluminum electrolysis. The possibility of gallium concentration was established via secondary pyro-selection of the dust. Kinetics of interaction of dust components with sulfuric acid was studied. The products of the interaction subsequently were leached with water. Optimum conditions for direct leaching with HCl and H2SO4 were determined providing gallium recovery from the cottrel dust and the ash carry outs up to 95 %. Gallium recovery from the primary dust and the secondary dust of aluminum electrolysis was at 52; 64 % and 63; 83 % respectively. Effect of Fe, P, K, Na and Al admixtures for gallium extraction from hydrochloric acid solutions was studied. It was shown that gallium chloride complex (GaCl4-) is extracted into the organic phase from the following acid mixtures: HCl + H2SO4, HCl + H3PO4, HCl + H2SO4 + H3PO4, HCl + HF. Kinetic regularities of gallium extraction in the system (tri butyl phosphate) TBP ? HCl - Ga were studied using diffusion cell method with agitation. Optimum conditions for gallium extraction from complex hydrochloric acid solutions with TBP were found providing 99.9 % recovery and separation coefficient for gallium and iron (III) of more than 25 in one stage. Sodium hydroxide and water were selected as reagents for re-extraction of gallium from the organic phase. Different options for disposal of by-products that are formed in the processing of cottrel dust, ash sublimates and dust of aluminum electrolysis were proposed and tested. Keywords: gallium, kinetic, sulfatization, leaching, extraction, technology

Sep 1, 2012

By E. L. Chanturiya

During the mineral processing of pyrites sulphide ores of some deposits of Russia loss of gold with tailings and pyrite concentrates amounts up to 40%~90%. The problem of selective allocation of gold-bearing pyrite is crucial. There are 4 mineralogy-technological groups of pyrite determined in copper-zinc sulphide ores, based on the increase of contents of gold in pyrite. The gold associated with group 4 pyrite contents of 85% the total mass of gold found in the pyrite. The flotation behaviour of the enriched fractions of pyrite (98%), of the allocated from the ore of Gay deposit, were studied essentially in various conditions ?? and the charge of Butyl xanthogenate of potassium (ButX). Some products of selective pyrite flotation were investigated by methods of scanning electronic microscopy, energy-dispersive and X-ray spectral microanalyses, definition of specific resistance and thermoelectric moving force.

Jan 1, 2014

By Z. Cheng, Y. Han

"For non-sulphide minerals such as oxidized minerals, fluoride minerals, and oxysalt minerals, there are generality in the molecular structure of their floating collectors, and similarity in crystal structure of the minerals. In the paper, adsorbing mechanism of these collectors on the surface of these mineral particles in different pH pulp was investigated by means of Pauling's rules & valence bond theory, Valence-shell electron pair repulsion theory (VSEPR) theory, Crystal and ligand field theory, and quantum chemistry simulation by DMol3 and CASTEP modules of Material Studio software. Besides, the role and status of hydrogen bond in the floating adsorption mechanism were studied emphatically, and the confirmation and characterization of hydrogen bond were explored also based on the test results. What is more, the conclusion “the effect of hydrogen bond can not be overlooked in adsorbing mechanism of flotation collectors on the minerals” and a new viewpoint of multi-polarity collaboration and hydrogen bond coupling were summarized eventually based on analysis of the measurements. Finally, a novel collector 2-Amino-3-Methyl Heptyloxy-Propylamine (AMHP) was developed based on the new viewpoint of molecular structure design, and its collecting performance was exhibited.INTRODUCTIONWhen it comes to the recovery of flotation, it is necessary for researchers to investigate the flotation mechanism of collectors. In traditional theory, when collectors were used to collect minerals, the attractions between collectors and minerals were divided into chemical, electrostatic and physical attractions (Wills, B.A., 2006). Especially, because of the reaction between sulphide minerals and sulphydryl collectors is complex and various mechanism has been proposed (Yoon and Basilio, 1993), when collectors were used to collect non-sulfide minerals, it can be classified into oxyhydryl anionic collectors and cationic collectors. In traditional theory, the adsorption of oxyhydryl anionic collectors were due to water-repulsion, and the adsorption of cationic collectors were due to electrostatic attraction between the polar head of the collector and the charged electrical double layer on the mineral surface (Wills, B.A., 2006)."

Jan 1, 2018

"The most common agglomeration technique in iron and steelmaking is sintering, which requires the use of iron ore/concentrate mixtures, limestone and dolomite as fluxes and coke as fuel in order to produce the required melt at high temperature to cause agglomeration of the particles. Sinter feed blends containing high proportions of magnetite concentrate are difficult to granulate and to produce granules of high permeability, and sufficiently robust quasi-particles for successful sintering operations. Since the granulation of iron ore sinter feed requires no use of a binder, the added fluxes play a vital role in holding the granule particles together until they sinter. The fluxes also help to improve the granule quality and control slag composition in the blast furnace. It is well-known that the particle size distribution of the fluxes affects the granulation effectiveness and green bed permeability which determine the productivity, physical and metallurgical properties of the granules and sinter. Hence it is necessary to understand the role of flux particle size on granule properties so as to improve the granulation of iron ore sinter feed blends containing high magnetite concentrate. In this study, laboratory granulation experiments have been carried out on iron ore sinter feed blends containing high proportions of magnetite concentrate at different addition levels of limestone and dolomite mean particle sizes, to understand the influence of limestone and dolomite particle sizes on granulation rate processes and granule properties.INTRODUCTION Increases in iron ore production to meet the global demand for iron and steel products has led to the depletion of high grade iron ores and thus the current utilisation of low grade iron ore fines and concentrates. However, sinter, pellets and the lump are the required feed types used in the blast furnace. The high basicity sinter is the main iron bearing feed accounting for 70-85% in the blast furnace due to its good metallurgical and mechanical properties that allow high productivity, efficient processes and low production cost (Adam et al., 2017)."

Jan 1, 2018

By A. V. Zimin

It is a well-known fact that usage of reverse cationic flotation in magnetite ores processing enables to improve the quality of magnetite concentrates. We designed an iron ore concentrate technology (with 70 -71 % of iron) including reverse cationic flotation in pneumo-mechanical flotators RIF (developed by RIVS Corporation, Russia) with good biodegradable etheramines as collectors for flotation of quartz. Practical application of high biodegradable flotation reagents decreases environmental impact risk of objects and enterprises of mining industrial complex. This work presents results of development of flotation technology for production of high quality ferruginous concentrates from magnetite ores of Russia and Ukraine deposits. Keywords: magnetite ores, reverse cationic flotation, ferruginous concentrates, pneumatic-mechanical flotation machines, environmental impact

Sep 1, 2012

By W. G. Liu

Phenyl malonic acid (PMA), a new chelating collector, which contains a phenyl structure and a malonic acid chelating group, has been synthesized and its collecting capabilities to calamine, hematite, quartz and hemimorphite are also studied in laboratory. From the experimental results, it can be seen that the PMA has somewhat flotation ability to calamine, hematite and quartz, while it nearly has no collecting ability to hemimorphite. With the increase of PMA concentration, the flotation recovery of calamine increases. When the dosage of PMA was 560g/t and at pH=7~9, the flotation recovery of calamine gets its maximum of 45.94%. The test results about the influence of pH on the flotation recovery of quartz show that the flotation recovery increases with the increase of pH, and the maximal flotation recovery can be gained in alkaline media. On the other hand, PMA has stronger flotation capability to hematite than to other minerals. The flotation recovery of minerals increases with increase of PMA concentration. When the dosage of PMA is 560g/t and at pH=5~7, the flotation recovery of hematite is 82.96%. Mean-while, the influence of pH on the flotation recovery of hematite was studied and test results showed that, as pH increases, the flotation recovery sharply rises until pH=4, then the increasing rate de-creases outstandingly, at pH=6 the flotation recovery reaches its maximum of 82.96% and it de-creases speedily in alkaline media. Finally, through the measurement of infrared spectroscopy and in terms of solution chemistry of collector, the flotation mechanism has been discussed. It was concluded that the adsorption of PMA on minerals surface is chemical adsorption in nature through two oxygen atoms in the polar group of phenyl malonic acid chelating with the metal ions of minerals surface to form a hexagon-cycle chelate complex: C(=O)-O-M-O-(O=)C.

Jan 1, 2014

By A. Koizhanova

Kumistinskoye gold- and silver bearing ores (Republic of Kazakhstan) as well as standardized test solutions containing gold, silver, copper, zinc and iron were studied. The best results in silver and gold recovery from Kumistinskoye gold- and silver bearing ores were achieved through use of complex cyanide-thiosulfate solutions as compared to individual cyanide solutions and thiosulfate solutions. It was found that such complex solutions substantially step up leaching process herewith increasing precious metals recovery rates. Thermodynamics of studied chemical processes was calculated. Reaction order, kinetic constant and activation energy of gold leaching process through use of cyanide-thiosulfate solutions were identified. We managed to prove that the sorption rates and holding capacity in process of gold anions recovery with anionite AM-2B are comparable to sorption characteristics for cyanide solutions. Keywords: gold, silver, copper, zinc, iron, cyanide-thiosulfate solutions, anionite AM-2B

Sep 1, 2012

The quality of iron ore fines in terms of high iron content and low levels of deleterious impurities such as Silica, Alumina, Sulphur and Phosphorous is a critical parameter, in sintering and subsequent iron and steel making processes. As the higher-grade ores become depleted, there will be a stronger focus on treating lower-grade haematite/goethite ores and developing suitable beneficiation techniques to reduce the levels of impurities. Innovative flow sheets, based on new and commercially available technologies, is required. These will be needed to include gravity concentration devices, which can handle coarse and fine feed sizes. In this paper, efforts made to reduce the silica and alumina content of a low grade iron ore fines (<1.0 mm size) sample from the Pilbara region in Western Australia are described. The feed sample, a goethite abundant lower grade iron ore fines, which was a plant reject assaying 48.66% Fe with 13.61% SiO2and 5.09% Al2O3 was investigated. To this end, an experimental campaign was undertaken, and beneficiation studies were conducted on the sample using a Floatex Density Separator (FDS), a gravity device which can be operated for size classification and/or relative density separation. The objective was to produce high-quality iron ore material suitable as sinter feed. An iron concentrate with a grade around 57.0% Fe (Calcined Fe of about 63.0%) was achieved while recovering around 67.0% of the feed weight. In addition, a rejection of substantial content of Silica (>75%) and Alumina (>66%) was achieved while securing >77% iron recovery. On the other hand, sharp classification efficiency with low values of imperfection around 0.20 was obtained. Consequently, the response of the lower grade iron ore sample to FDS application, has vast potential to reject deleterious impurities as a single stage separating beneficiation equipment. Remarkably, it was demonstrated, that a great amount of goethite, abundant in lower grade iron ore fines/plant rejects, which are currently being either stockpiled and/or dumped as waste, can be treated using FDS application and potentially can add a significant value to the iron ore mining industry by recovering additional iron ore fines. Keywords: deleterious impurities, beneficiation techniques, classification, relative density separation

Sep 1, 2012

By Kremena Dedelyanova, Tsvetan Damyanov, Nikolay Hristov, Evgeni Kostadinov, Lubomir Kuzev

"Spherical grinding media (balls) are the most widely used media for comminution of ores by grinding. One way to optimize the grinding process in a tumbling mill is associated with the development and testing of a new media shape. By modelling simulation study of the behaviour of two types of grinding media (balls and tetraballpebs) in the grinding process was conducted to determine the possible advantages of the new media shape. Tetraballpebs are in the shape of tetrahedrons with spherical convex walls. D305 mm and L305 mm Bond ball mill sizes were used in the experiment. They are modelled milling tetraballpebs bodies corresponding by weight to five ball sizes, namely ¾, 7/8, 1, 1¼ and 1½ inches which form the grinding media used in a Bond ball mill. They are cast steel grinding bodies. Studies carried out with both types of grinding media include equal number of milling bodies of the same weight and volume. Having thus ensured a uniform mass of the grinding media and the same number of milling bodies, all other conditions and process parameters being identical, conclusions can be drawn about the influence of the grinding media shape on the grinding process. Compared to steel balls, the tetraballpebs used in laboratory tests carried out in closed cycle by Bond ball mill and the study of the rate of grinding gave five to six per cent higher yield of a control size of minus 0.1 mm. Measurements of the Bond ball mill power consumption demonstrated that tetraballpebs grinding media achieved energy saving of 4.7 per cent for the production of one gram of the control size of minus 0.1 mm."

Jan 1, 2014

By Hoon Lee

Laboratory tests were conducted to evaluate the breakage characteristics of pyrophyllite in a laboratory ball mill. In grinding tests, the breakage characteristics were analyzed using the mathematical kinetic models based on the two breakage functions; the specific rate of breakage and the primary breakage distribution. Two samples having similar chemical composition show identical values in specific rate of breakage. In comparison, there are different values of primary breakage distribution for each sample. The size distributions of the product with various grinding time are well described by the parameters from non-linear searching.

Sep 1, 2012

By R. C. Miranda

Flotation is an operation widely used in mineral processing because of its aptitude to recover minerals of interest very efficiently. Flotation is often responsible for making possible the exploitation of mineral deposits of low concentration. In flotation various processes phenomena occur, some of which have still not been explained scientifically. Due to this fact, there are no models that can be widely applied in flotation control. Thus, in most cases, the control is done by experienced operators who are able to visually classify the types of foam into different categories and each one of them is associated with an operating actuation. In this situation, image analysis is configured as a solution that has already been employed in several ways. In this paper, a control strategy based on the colour of froth on a direct flotation of a nonferrous metal is presented. Moreover, the paper reveals the theoretical basis of the method, the critical points, difficulties and improvements that can be implemented. Data of grade were collected from the mineral of interest and RGB (red, green and blue) data of final concentrate of the froth. The mineral grade was collected and analysed during one month of operation and RGB was obtained using a camera. It was verified that the red colour showed the same trend of the grade curve in the concentrate. Thus, the use of this online data in optimising control was introduced. The laboratory grade is used to calibrate the colour set point. Therefore, it was possible to monitor in real time the trend of enrichment and depletion of a non-ferrous mineral in a flotation. It was possible to establish an online control strategy based on simple data acquisition. The result was an increase of 10% on production.

Sep 1, 2012

By A. O. Gapchich, T. N. Matveeva, N. K. Gromova

"Tin sulfide ores and aged man-made products obtained after their processing are distinguished by a complex material composition and uneven impregnation of sulfide minerals (chalcopyrite, galena, arsenopyrite, etc.) and tin ore (cassiterite). Enrichment of such ores is performed through sophisticated multistage schemes using not only gravitational methods, but also gravity flotation, flotation, magnetic separation techniques. Tin ores also contain rare and precious metals (indium, scandium, silver), characterized by fine dispersity and microscale to nanoscale fineness of mineral formations. During flotation concentration these metals are extracted along with the main ore minerals into concentrates (tin, copper, tungsten, etc.), however, up to 10-20 % of them are lost with final tailings. The aim of the work is an experimental study of the modification of the surface of sulfide minerals and cassiterite by stable metal-collector complexes to increase extraction of fine tin, silver, copper and other metals from complex tin ores. Triamide cyanuric acid (TCA) was studied as a thin silver flotation modifier. Thermophilic polymer with a functional group of phenylphosphine TMPPh was used as a selective flocculant. For experimental studies of the physical and chemical effects of collecting agents on the surface of minerals the following analytical techniques were used - the analytical scanning electron emission ASEM (LEO 1420VP INCA OXFORD ENERGY 350) and laser (KEYENCE VK-9700) microscopy, measurements of electrode potentials of mineral anthills by potentiometric titration, monomineral and pulp flotation. New data on formation of the adsorbed layer of DBDTC on the surface of chalcopyrite, galena and arsenopyrite were obtained, and the dimensions of the reagent films and the strength of their adsorption. The indiscriminateness of cassiterite to DBDTC ensures its selective separation into a chamber product during the flotation of sulfides. It is shown, that modification of the sulfide surface by stable complexes Me-DBDTC and Ag-TCA-TMPPh will increase the recovery of non-ferrous metals and silver into a collective sulfide concentrate and will provide a high-quality tin concentrate for flotation of tin sulfide ores.The studies were perfomed with the aid of the Russian Science Foundation (Project No. 17-17-01292).INTRODUCTIONTin sulfide ores and aged man-made products obtained after their processing are distinguished by a complex material composition and uneven impregnation of sulfide minerals (chalcopyrite, galena, arsenopyrite, etc.) and tin ore (cassiterite). Enrichment of such ores is performed through sophisticated multistage schemes using not only gravitational methods, but also gravity flotation, flotation, magnetic separation techniques. Tin ores also contain rare and precious metals (indium, scandium, silver), characterized by fine dispersity and microscale to nanoscale fineness of mineral formations. During flotation concentration these metals are extracted along with the main ore minerals into concentrates (tin, copper, tungsten, etc.), however, up to 10-20 % of them are lost with final tailings. In this regard, it seems advisable to use new varieties of flotation reagents in order to increase extraction of finely dispersed tin, silver, copper and other non-ferrous and precious metals from multi-metal tin ores (Bocharov and Ignatkina, 2007; Khanchuk etal., 2012; Wu and Zhu, 2006; Yusupov etal., 2016)."

Jan 1, 2018

By E. Gock

Based on the scientific investigations on mechanochemical synthesis of metal sulphides from metals or metal compounds and sulphur or sulphur compounds, the article describes the industrial production of nanoscale metal sulphides. Special operational conditions such as inert atmosphere, size and type of the grinding balls, grinding time and specific energy input are taken into consideration. A system configuration for the manufacturing of sulphides at a capacity of 100 kg/h is presented.

Jan 1, 2014

By Andrey V. Yevdokimov

The results of the test work on gold leaching using high strength of cyanide solution in the presence of activators are presented. The major physical and chemical relationships of gold leaching were determined. Intensive cyanidation results of gravity concentrates with various material compositions using an activator are given. Process design criteria for intensive cyanidation unit were developed on the base of pilot plant test results. Keywords: gold, activators, intensive cyanidation, gravity concentrates

Sep 1, 2012

By S. Banisi, A. Ghasemi, S. Zare, F. Ghorbani, E. Nematollahi

"Comminution is the most energy intensive operation which constitutes the major portion of operating and capital costs of the mineral processing plants. Working at the maximum operating capacity of comminution equipment plays a significant role in the efficiency of the circuit. Appropriate design of cone crusher feed box could result in the choked crushing which is known as a vital factor in achieving target performance. In this research, the non-uniform cone crusher feeding at the Sarcheshmeh copper complex was studied and appropriate measures were taken to solve the problem. The problem resulted in non-uniform and high wear rate of crusher liners and high fluctuations of power draw. In recent decades, the discrete element method (DEM) has been applied successfully to study the effect of different factors on the behavior of particles flow. In this work, various designs for feed box were tested using an in-house developed DEM software called KMPCDEM©. The best feed box design obtained from the simulations was selected, constructed and installed in of the cone crushers. The new feed box design resulted in more uniform feed distribution on the distributor plate of crusher indicated by a reduction of the standard deviation of power draw measurements from 13 to 3 kWh. The better control of the crusher, 49% increase in the crusher throughput and finer and narrower product size distribution were the main outcomes of the installation of the new feed box. Furthermore, the wear rate on mantle and liners of crusher not only decreased but it also became uniform.INTRODUCTION Comminution is the most energy intensive operation which constitutes the major portion of operating and capital costs of the mineral processing plants. Reaching the maximum operating capacity in comminution equipment is a key sign of approaching the nominal productivity of the process. Due to the effect of crusher efficiency on the downstream circuit performance, optimization of the crushing circuits has received considerable attention (Herbst, & Potapov, 2004; Quist, & Evertsson, 2010; Li, Huiqi, McDowell, Glenn R, Lowndes and Ian, 2014; Cleary, Sinnott, Morrison, Cummins, & Delaney, 2017). Improving the performance of crushing circuits not only decreases the capital and operating costs but also increases the efficiency of downstream grinding circuits (Jacobson, Janssen, & Urbinatti, 2010). In cone crushers particles can be subjected to two different modes of compressive breakage; single particle breakage (free feeding) and inter-particle breakage (choked feeding). The maximum efficiency of the cone crusher directly depends on the type of feeding arrangement (Operation Manual, 1977). An appropriate feeding must lead to choked feeding the cone crusher. If the rate and method of feeding the crushers are correctly be executed, the maximum efficiency of the crushers could be available (Jacobson et al., 2010)."

Jan 1, 2018

By G. Sedelnikova

This paper is aimed to elucidate the problem of copper losses in pyrometallurgical slag. Currently, flotation is used to recover copper from the slag and return the metal into the pyrometallurgical process, but the percentage of recovery frequently remains unacceptable. The process of copper leaching from the slag flotation tailings using biologically regenerated ferric sulfate is considered here as an approach to the issue. A sample of the slag flotation tailings containing 0.67% Cu and 4.99% Zn was supplied by the Urals Mining and Metallurgical Company (UGMK, Russia). The Cu and Zn speciation analysis of the sample demonstrated that Cu occurred as 58.1% oxide, 15.4% native Cu, and 18.1% secondary sulfides whereas chalcopyrite proportion was as low as 8.4%. Prevailing Zn species were refractory (58.9% Zn ferrite), and zinc oxide and silicate species made just 37.2% of the total metal content. The silicate generated silica gel that strongly hampered filtration. As demonstrated, Cu recovery is a possibility, which is apparently not the case with Zn. In this work, the stirred tank bioreactor acid leaching employing bacterial Fe3+ sulfate solutions was studied, with ferric sulfate being a product of Fe2+ biological oxidation and not the chemical reactant adding of Fe3+ sulfate. Acidithiobacillus, Sulfobacillus, and Leptospirillum bacilli were employed in Fe2+ biooxidation. Temperature, pH, Eh, S:L ratio, leaching time, and Fe3+ concentration in the source leachate as the process controls were considered. As demonstrated, the process employing biologically regenerated ferric sulfate proved to be more efficient than conventional chemical leaching. Under the optimum conditions, the proportion of Cu extracted into leachate during 2 hours was 79.1%, and that of Zn 27.2%. Precipitation of high-grade Cu sulfide served to extract the metals from the leachate, and Cu extraction was 99.7%. All in all, 23.2% Cu, 0.03% Zn, and 0.02% Fe was returned into the pyrometallurgical process. Keywords: slag flotation tailings, copper leaching

Sep 1, 2012

By B. Suresh

Iron ore in Bellary-Hospet region is friable in nature and generates a significant amount of micro-fines (-150 µm) during mechanized mining, handling and processing. Present beneficiation practice generally employs spiral classification followed by hydrocycloning to remove slimes (-15 µm). The iron ore fines, beneficiated at JSW Steel Ltd., Karnataka generates tailing having 48-52% iron content in the form of slimes, which accounts for 50 to 55% by weight with respect to classifier overflow. The loss of iron as slime is considerably high. In this context, laboratory studies were carried out with different combination of beneficiation techniques with an objective to develop an efficient flow sheet to achieve better product grade and recovery from classifier overflow. The results revealed that de-sliming process by hydrocycloning in combination with either magnetic separation or froth flotation leads to increased iron loss in tailing. Based on investigation it is observed that forward flotation is beneficial over the reverse flotation. The experimental approach of forward flotation on classifier overflow followed by magnetic separation on flotation tailing resulted in overall product grade of 62.9% Fetotal and 70.3% yield. The tailing contains 34.6% iron, which accounts for 29.7% by weight with respect to classifier overflow.

Sep 1, 2012

By Dmitriy Makarov

The paper presents the modeling and analysis of oxidation of pyrite copper-zinc ore samples from the Letnee, Yaman-Kasy and Valentorskoye deposits. It is found, that the oxidized samples contain copper and zinc sulfates that are leached under the sample and water contact. It is shown, that sulfide floatability is decreased by the longer-term oxidation.We advise to improve nonferrous metals recovery by joint leaching and ultrasonic treatment of oxidized compounds. Study of the geotechnological processes of non-ferrous metal extraction, on the basis of two copper-zinc ore deposits shows, that heap leaching is of little use for the ores of the Letnee deposit. Leaching results for the Yaman-Kasy ore showed more promise.

Sep 1, 2012