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By K. D’Elia, L. D. Ogrel, O. A. Malyshev, T. I. Yushina, I. M. Petrov

"The purpose of this research is to develop enhancements in the mineral processing by flotation methods of nonferrous ores. Currently, 180-190 million tons of ore are processed by flotation in Russia. The annual processing volume of copper-nickel and copper-zinc ores exceeds 20 million tons. In the total volume of processed ores by flotation, non-ferrous ores account for roughly 35% and ores of precious metals for another 15%. The total demand of flotation reagents in Russia in 2016 was estimated at 170,000 tons. Sulfur-based collectors used in the flotation of non-ferrous sulfide ores (typically, xanthates) do not always offer sufficiently high recovery of valuable components.It has been found that reagents like DMIPEC and DK-80 improve the recovery of metals into concentrates. To identify the reasons of that higher recovery, quantum chemical calculations of the mechanism and interaction forces of DMIPEC with non-ferrous sulfides were undertaken by determining the stabilization energy of the resulting chemical complexes. It has been shown that, in the interaction of DMIPEC and DK-80 with the surfaces of sulfide minerals, ethylene and acetylene bonds act as the reaction centers, and the formation of molecular p-complexes is the result of metal-cation interactions with the surface and the flotation reagents.In the flotation of non-ferrous ores, DMIPEC and DK-80 act as selective supplementary collectors with foaming properties, and at a flow rate of 3-35 g/ton, they reduce the flotation time, and increase copper recovery by up to 3.5%, zinc recovery by up to 12%, gold recovery by up to 8-10%, allowing to increase the recovery of valuable components by 1.5-12.0%, basically this kind of reagents nearly double the flotation rate, improve the grade of the concentrate, improve the stability of the flotation process parameters, and reduce the environmental impact of flotation plants."

Jan 1, 2018

By U. Dmitrakova, G. Sedelnikova, D. Kim, E. Savari

"The paper presents the results of research on the development of gold and silver extraction technology from refractory gold sulphide flotation concentrate of one deposits of Nord-East of Russia. The concentrate is due to the complex mineral composition. Gold and silver are finely disseminated in sulphide minerals (arsenopyrite and pyrite partially oxidized by 7-11%). These are characterized by high content of silver 219 g/t and sulphide sulfur 32%, the presence of poorly soluble silver minerals (silver sulfosalts, fahlore, finely dispersed hypergenic acanthite in iron hydroxides and jarosite, etc.), and impurity minerals capable of interacting with cyanide (pyrrhotite, marcasite, nonferrous sulphides) and causing higher than normal cyanide consumption. Pretreatment of refractory sulphide concentrate by biooxidation using a mixed association of mesophilic and moderately thermophilic bacteria at a temperature of 36-40 °C for 120 hours oxidized arsenopyrite by 97.5%, pyrite by 93.5%, unlocked refractory gold, and generally oxidized the minerals absorbing cyanide and oxygen before cyanidation. Further oxidation of these minerals-absorbents was facilitated by the aeration in calcareous medium of the solid biooxidation residues of the concentrate. Sorption cyanidation of the solid biooxidation residues with addition of lead (II) of recovered 91.2% of gold and 82.9% silver from biooxidation residue, compared with 80.1% and 46.6%, respectively, for sorption cyanidation without the preceding biooxidation step. Biooxidation of the concentrate prior to cyanidation improves the recovery of precious metals, especially silver, and significantly reduces cyanide consumption from 18.7 kg/t to 3-5 kg/t of concentrate. INTRODUCTION Biooxidation of gold sulphide concentrates using acidophilic microorganisms has been successfully applied worldwide (van Aswegen et al., 2007; Gericke et al., 2009; Sovmen et al., 2007; Sovmen et al., 2009). At least 15 full-scale plants for tank biooxidation of sulphide concentrates are presently in operation, and the construction of new ones is planned (Bulaev et al, 2015)."

Jan 1, 2018

By M. M. Kulkarni1

Kaolin clay is used as a filler and pigment in various applications such as paper, paint, rubber, plastics, adhesives, ink and ceramics etc. Major mineral content in crude kaolin clay is kaolinite along with some accessory minerals as quartz, hematite, mica, feldspar, anatase, rutile, illemnite etc. The Fe and Ti bearing minerals play very important role in determining quality of the kaolin, as these minerals impart yellow, pink or darker color to the white kaolin. Conventional beneficiation methods used in kaolin processing are de-gritting, classification and sodium dithionite bleaching, which improves the optical properties of kaolin, wherein reduction of color imparting constituents such as Fe2O3 and TiO2 is marginal. In the present study, these coloring impurities are separated using selective adsorption of water-soluble polymers. Degritted kaolin samples after passing through 45 micron sieve is used in the study for selective flocculation by polyacrylamide based polymers. The effect of pH, zeta potential, and polymer dose on the reduction of impurities is studied. Analytical tools such as XRF, XRD, SEM, and TEM techniques are utilized and results are discussed in detail.

Sep 1, 2012

By M. P. Krasteva

The froth flotation process for separation of mineral ores depends on the establishment of care-fully controlled froth. The formation of very stable froth in the flotation circuit is a problem that may occur in many plants, resulting in down-time, low quality and grade of final product and considerable expenses. Froths build up on the top surfaces of thickeners, tanks and flotation cells until they overflow, or until the efficiency of the circuit is impaired. A similar problem exists in Assarel concentrator, Assarel-Medet PLC, Bulgaria. Copper and copper-pyrite ores are dressed in Assarel concentrator. They are characterized with variable and complex mineral and physical composition. During the flotation cycle, resilient and difficult to break-down froth is formed, which subsequently impedes the process of thickening and clear overflow obtaining. Due to this problem continuous sampling in the cycle of thickening was conducted. The mineralogical, chemical composition, particle size distribution and solid phase content of the products were determined. It was established that the solid phase of the froth build up on the top surface of the thickener differs considerably from this one of the thickener underflow. The data clearly indicates that a separation process takes place on the top surface of the thickener ? fine particles of chalcopyrite are concentrated in the froth. The role of chemical reagent addition in the break-down of the flotation froth is investigated in terms of surface chemical phenomena involved in the stabilized froths. Measurements of the coper minerals wettability and surface tension at the air/liquid interface were performed. The surface active agent AERODRI® dewatering aids were laboratory tested. Bench-scale froth collapse tests were conducted. Reagent addition into pulp-froth system promotes and leads to a bubble coalescence, an improvement of the wetting of the mineral particles and a decrease of the surface tension at the air/liquid interface. The results of the laboratory experiments showed that the presence of the surface active agent leads to considerably decrease of the froth stability and the destruction of the deleterious froths build up on the top surface of the thickeners in Assarel concentrator.

Jan 1, 2014

By V. Runkana, N. K. V. Nadimpalli, S. Sahu

"IsaMill™ has been in operation in the recent past for fine grinding of low grade ores to extract non-ferrous minerals. IsaMill™, typically, consists of a series of uniformly spaced identical disks mounted on a rotating shaft which is encased in an outer shell. The mill offers high energy efficiency for fine grinding and an inherent scalability. But, it encounters certain operational challenges such as non-uniform distribution of grinding media coupled with high wear rate of the disks and solid walls of the mill at specific locations—which adversely affect the mill performance. To circumvent these operational challenges, design modification of the disks through heuristics, by introducing a reduced diameter disk (RDD) at specific locations, is a common practice in industry. But there is no systematic scientific study in this regard. In the current work, we developed a discrete element method (DEM) based model and simulated for the IsaMill™ operation to study the effect of RDD on the efficiency of the mill and wear rate of the solid walls and disks. Since the first set of disks experience the high wear rate due to the high loading of the charge, the RDD was introduced at the first two disks. The simulations were performed at different diameters of the RDDs and at different media loadings. The performance of the mill was analyzed based on the power consumption, the wear rate on disks and the distribution of media particles inside the mill. Besides, the performance variables such as mean velocity of media particles and total impact energy provided useful insights into the milling operation. It was observed that the reduction in disk diameter yields lower wear rate of the disks at the cost of decrease in power draw at a constant high media loading. Whereas, when the media loading was decreased, the amount of wear and power drawn was comparable for both the most reduced and least reduced disk diameters. Therefore, there is an optimum choice of RDD for a given mill loading to maximize the mill performance while reducing the wear rate of the disks."

Jan 1, 2018

By Masanori Mori, Hajime Miki, Osamu Ichikawa, Tsuyoshi Hirajima, Mitsuru Sawada, Keiko Sasaki

For pretreatment of selective flotation, surface oxidation of chalcopyrite and molybdenite was applied by oxygen plasma then the minerals were washed by solution at pH 9 with oxygen bubbling. Surface characteristics of these minerals were investigated with AFM, XPS, zeta potential and contact angle measurements. Contact angle of chalcopyrite and molybdenite decreased a lot by plasma treatment. When they were washed with pH 9 solution with oxygen bubbling, contact angle of molybdenite increased whereas chalcopyrite one kept low. Adhesion force measurements indicated similar behavior. Result of flotation experiments indicated low recovery of both chalcopyrite and molybdenite after plasma treatment and only molybdenite recovery became higher after washing. Selective flotation of chalcopyrite and molybdenite could be achieved with this process. Possible mechanism of selective flotation was proposed from the results of XPS, AFM, etc.

Jan 1, 2014

Much has been published in recent years on the challenges facing the engineer of the 21st century and the consequent challenges facing the education providers and industry. The world is changing rapidly on the social, economic, political, technical and environmental fronts and our metallurgists/mineral processing engineers of the future will arguably need to have a different set of skills than those which were traditionally regarded as adequate during the latter half of the 20th century. This paper attempts to explore some of these issues and their ramifications.

Jan 1, 2014

By M. Nonaka

An attempt to produce fuel from biomass waste by hydrothermal treatment has been made with expectation to effectively utilize a renewable source of energy and an unexploited energy resource. In this paper, we have used empty fruit bunch (EFB) that is a residue after recovery of crude palm oil from palm oil trees in a plantation in a tropic country. A hydrothermal treatment was conducted using a 500 mL autoclave, with alkali (K2CO3) catalyst. EFB was decomposed more by alkali catalyst of lower alkali content and rather polymerized in higher catalytic region. The functional group composition of the solid phase oil is similar independent of alkali content, however its burning characteristic became more incombustible with increasing alkali content.

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

By Gurubasayya Swamy

This paper presents the consequences of modernization and expansion of process plant by implementing SAG and Ball Mill and Carbon-in-pulp technology at the Hutti Gold Mine. From the inception of the process plant, it has undergone many changes for the improvement. In the beginning, only gravity recovery of gold was carried out by using Pebble Mills and Strake Tables. Later amalgamation, Cyanidation and Zinc precipitation and finally Carbon-in-pulp gold recovery system was implemented. Grinding plant was modernized by implementing SAG and Ball Mill and Knelson concentrator for free gold recovery as a result, the production rate, rate of recovery, reduced man power, Modernization and expansion of process plant has also yielded in safe and smooth running of the plant. Keywords: sag and ball mill, cip, modernization and expansion, productivity, gold recovery

Sep 1, 2012

By S. J. Liu

The conventional collector for bauxite mineral is oleic acid, which is highly insoluble and must be used in high dosage in bauxite flotation operations, that is the great drawback of oleic acid in use. A series of hydroxamic acid were synthesized, and their collecting ability to certain minerals in bauxite: diaspore, kaolinite were studied. The collecting power of various reagents to diaspore in an incremental sequence were shown as follows: benzyl hydroxamic acid<amylic hydroxamic ac-id<heptylic hydroxamic acid<oleic acid<octylic hydroxamic acid; while the incremental sequence of the collecting power to kaolinite was like this: benzyl hydroxamic acid<amylic hydroxamic ac-id<heptylic hydroxamic acid<octylic hydroxamic acid<oleic acid. It could be seen that octylic hydroxamic acid had the capability of high collectivity and good selectivity, and octylic hydroxamic acid was chosen to use in the following experiments. Reduced zeta potential showed the adsorption of the anionic collector on the mineral. By the adsorptive capability and IR tests, the adsorption of octylic hydroxamic acid on diaspore was determined to be chemical absorption, which was greater than that of oleic acid, as it was physical absorption. Results of floatation experiments on manually mixed minerals indicated that the collectivity and selectivity of octylic hydroxamic acid were better than oleic acid.

Jan 1, 2014

By C. A. C. Sequeira, G. N. Anastassakis

"The separation of fine or even smaller size mineral particles with conventional methods is inefficient due to the specific properties of fines (small mass, high specific surface area, and high surface energy per unit area). Hence, the production of high-grade concentrate with high recovery is very difficult to impossible and a significant share of mineral values is lost to the tailings. The aim of the current research is to investigate the possibility to efficiently separate value minerals from gangue of fine particle size. The objective of the current work is to develop separation schemes of fine mineral particles by combining an initial stage of particles agglomeration with the use of collectors (hydrophobic agglomeration) with a subsequent conventional separation method. In the current research, magnesite was used as mineral value to be separated: a) from quartz, and b) from mineral mixture (serpentine, ilmenite, and olivine). In each case, tests on single minerals and artificial mixtures were carried out. After hydrophobic agglomeration, the separation of magnesite from quartz was achieved by settling; in the second case (gangue: serpentine, ilmenite, and olivine), magnetic separation of the co-agglomerated gangue was applied. In both cases, the results of the preliminary tests on single minerals suggest that the separation of mineral value is feasible and efficient. These findings were also confirmed from the results of the tests on artificial mixtures of magnesite and gangue, either quartz only or mineral mixture. Both separation schemes provided with magnesite concentrates of commercial grade (95% magnesite) with high recovery. INTRODUCTION The generation of fine particles is inevitable in many operations of mineral commodities processing. Especially in the case of low-grade ores, the mineral value is finely disseminated in the ore, and considerable liberation occurs at a fine size range. Although there is not a uniform classification system with respect to mineral particles size, fines are usually characterized the particles with a size range of -100µm+20µm, very fines those of -20µm+5µm, ultra fines of -5µm+1µm, and colloids smaller than 1µm (Sivamohan, 1990)."

Jan 1, 2018

By Sergey S. Gudkov

In the current climate of changing the approach to mining and treatment of mineral resources, processing technologies are being developed that require little maintenance and are economically as well as ecologically sustainable. This may also involve the development of entirely new ways of ore processing. One promising approach is to use bioleaching for the pretreatment of gold refractory ores to cyanidation. Capital costs for vat bioleaching of concentrates and ores are very high and cannot be applied for small or medium-size deposits. IRGIREDMET JSC carried out bio heap leaching test work on refractory ore samples from three Russian deposits. Following this biological treatment a combination of flotation, vat bioleaching, and cyanidation are used to recover gold. After heap bioleaching, gold recovery was 75-80 per cent. It was found that efficiency of heap bioleaching process depends on ore feed size. High duration of this process is another feature and it lasts for about a year. This process can be also used for carbonates in the combination with other process during which acid generation occurs. The results of our studies have shown that this technology is amenable for refractory gold ores. Its introduction allows an increase gold recovery and to solve a number of environmental problems. Keywords: heap biooxidaton, the refractory of the ores, the degree of oxidation, arsenopyrite, pyrite, CIL

Sep 1, 2012

It is well known that the crushing and grinding steps in the mineral processing of ores represent a substantial proportion of total energy, cost and carbon emission in mining. For instance a recent study calculated that 36% of the energy consumed by gold and copper producing mines in Australia was attributable to comminution (Ballantyne et al, 2012). Understanding this component of a business is essential in a world seeking to lower production costs, improve earnings and reduce its carbon footprint. The issue commands the attention and support of industry leaders in the mining sector, government, equipment manufacture, engineering design and research organizations. Furthermore, several researchers have often stated that globally, comminution processes consume between 3-4% of the world?s electrical energy production (Daniel and Lewis-Gray, 2011). In 2009-10, Australia?s Federal Government Energy Efficiency Opportunity (EEO) participants in the mining sector used 336.5 PJ, representing approximately 6 percent of Australia&apos;s total energy use. It is evident that the current practices of breaking rocks in tumbling mills are relatively inefficient (Fuerstenau and Abouzeid, 2002). Research and improved engineering design has established that a range of improved blasting, crushing and grinding techniques and flow sheets may lower project costs and carbon footprint. These include relatively simple process flow sheet strategies such as gangue rejection or pre-concentration prior to size reduction, a better combination of grinding technologies (both current and new systems), and selection of coarser grind sizes where ore and waste mineralogy allow. Yet, despite this systematic and detailed research, the industry remains somewhat reluctant to implement these strategies. CEEC (Coalition for Eco-Efficient Comminution) was established in 2011 to support knowledge sharing and change in an area of high-energy consumption for the global mineral industry. CEEC is a not-for-profit industry company, funded by grants from world wide industry companies, whose mission is to accelerate knowledge and technology transfer in the field of energy-efficient comminution. The key benefit to the mining sector arising from CEEC?s activities will be an increase in the rate at which more energy-efficient comminution data sets, processes, and technologies are developed, demonstrated, shared and applied. This will contribute directly to the industry?s target of reducing operating costs and carbon emissions. CEEC International Ltd and JKTech Pty Ltd teamed together to facilitate the inaugural CEEC Workshop, in June 2012. The purpose of the workshop was to produce a roadmap to provide guidelines for how (1) operations can achieve best EEC practice in the short to medium term, in collaboration with vendors, engineering companies and other service providers, and (2) what R&D is needed to achieve paradigm change in EEC in the medium to long term, e.g. 75% reduction in comminution energy in 10 years.

Sep 1, 2012

By B. Y. M. Bueno

Biosorption of heavy metals can be an effective process for the removal of heavy metals ions from aqueous solutions. In this study, the adsorption properties of Rhodococcus opacus biomass for Pb(II) and Cu(II) ions was investigated. The effects of initial pH, initial metal concentration and biomass concentration on biosorption efficiency were studied in a batch system. Results showed that the initial pH would play an important role in the Pb(II) and Cu(II) ions removal by R. opacus and affected the zeta potential of R. opacus. The equilibrium adsorption was reached with 60 min. The Langmuir and Freundlich models were used for describing of adsorption isotherm data. The maxi-mum adsorption capacities of biomass were determined as 94.3mgg-1 and 32.2 mgg-1 for the Pb(II) and Cu(II) ions, respectively. The experimental data fitted to pseudo second order kinetic model. Adsorption capacity of Pb(II) ions was found to be reduced by the presence of the other competing metal ions in the system. The FT-IR results of R. opacus biomass showed that biomass has different functional groups and these groups are able to react with metal ions in aqueous solution.

Jan 1, 2014

By M. Surracco, M. C. Tilocca

"Mineral comminution is often a costly process which also requires high level of energy. In the course of the studies carried out by the researchers of the Department of Civil-Environmental Engineering and Architecture at the University of Cagliari, aiming at the optimization of the reduction processes, it has been experimented, among of others, the effects of high-speed water jets on minerals grinding. As far as coal is concerned, some of the solutions initially adopted are presented in this paper, which essentially relied on the water jet power only, with secondary use of mechanical actions, to reach the most modern solutions that envisage the use of mechanical energy, normally used in traditional grinding machines, in synergy with hydraulic energy transferred by water jet.INTRODUCTION Mineral comminution can be rather expensive and demand a high-energy consumption, especially for fine sizes (Austin, 1979). Further interesting perspectives in this area may be offered by comminution means aided by high pressure water jets (Ciccu 2007), whose crushing potential is currently used for several operations such as cutting different materials, rock digging and industrial cleaning. The crushing action of water jets may induce a traction stress in materials where substances of a mineral nature, especially if characterised by permeable porosity, oppose a minor resistance (Griffith, 1920). The first solutions to this purpose essentially relied on the sole energy of water jets, with a secondary use of mechanical actions (Ciccu, 1993). Results were encouraging, despite the high values of specific energy for the low capacity of treatment. However, due to the difficulty in making the techniques mainly based on hydraulic energy practically applicable to solids comminution a solution was experimented, with some interesting results, consisting in the combination of mechanical energy, normally used in traditional grinding devices, with hydraulic energy transferred through water jets, in a synergic relationship (Ciccu, 1998; Tilocca, 2016)."

Jan 1, 2018

By C. L. Xiao

With reference to the test report carried out by Guangzhou Nonferrous Metal Research Institute in 1983, the mineral process flow sheet of Yichun Tantalum-niobium mine is determined based on the characters of ores and successful experiences in light of the problems in the existing flowsheet: The ore is desilted before crushing; the primary slime is separately treated; the staged grinding process used while the fine slime is collectedly treated with tantalum and niobium as the main recoveries and lepidolite and feldspar powder as the secondary. The flowsheet is featured by comprehensive recovery, low investment and low energy cost.

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

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 W. H. Cheung

Nickel and cobalt production relies heavily on the processing of nickel laterite ores; these ores contain the majority of known Ni and Co reserves, 80% and 90% ~ 95%, respectively. The Caron process is used to extract Ni and Co metals from low-grade nickel laterite ores (1% Ni and 0.1% Co). It involves selective reduction of NiO and CoO minerals followed by ammoniacal leaching. Despite low metal recoveries, this process continues to be technically and economically reliable and thus commercially important globally. However, keeping the Caron process cost-effective has been a challenge for industries because of increasing economic and environmental pressures. Although studies of the Caron process have been extensive, significant improvements in recoveries of industrial processes have not been forthcoming. Reported industrial metal recovery from high iron content ore is only 80% ~ 85% for Ni and only 40% ~ 45% for Co; recovery is even lower for ores rich in magnesium. The real difficulty here is that there is no complete understanding of and control over the complex series of reactions in the ore and in the leaching solution during processing. Achieving effective metal recoveries from the Caron will require control of the mineral transformations, which affect the activation of minerals by reduction. In this study, the effect of over-reduction was investigated, which superseded the effect of activation by lowering the activity of the minerals and thus metal dissolution. Reduction was carried out in a batch reduction apparatus with 1:1 and 1:2.5 CO/CO2 gas mixtures from temperatures of 500 ~ 700°C and residence times up to 60 minutes. The pre-reduced ores were leached using a standard ammoniacal leaching test. Thermodynamic analysis and possible effects of stable phase field on leaching was examined. The results suggest that control of over reduction effects are directly related to the mineral transformation and reduction conditions.

Jan 1, 2014