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Results of the study of chloride ion concentration effect to osmium-187 sorption from wastewater of copper smelter with use of foreign anionites of different basicity and structure are presented in the work. It was found that the increase of chloride ion concentration in the wastewater helps to increase recovery of osmium using anionites regardless of their nature. The ways to intensify the process are proposed. The method for osmium elution from the anionites with potassium iodate solution was developed. It was shown that the method lets to recover up to 99% of osmium from the anionites. Recommendations for selection of eluents for better recovery of osmium from the anionites were elaborated. Keywords: wastewater, osmium, anionite, sorption, chloride ions, eluent, recovery

Sep 1, 2012

By Yu. E. Emelyanov, A. V. Bogorodsky, R. N. Nabiulin, S. V. Balikov

"The paper describes the results of the study of gold-copper flotation concentrate atmospheric oxidation at different sizes of material, varying oxidation time, with air or oxygen blow. The study showed the low rate of sulphide oxidation during oxidation of flotation concentrate at a feed size (P98 -74 µm). The coppery recovery into solution was 48%; the recovery of gold by subsequent cyanidation reached 86%. Preliminary flotation concentrate grinding to P98 -20 µm provided oxidation of 90% of copper minerals, 80% of arsenopyrite and 15% of pyrite. The gold recovery by atmospheric oxidation of a fine-ground flotation concentrate increased by 59%, from 36% to 95%, the NaCN consumption reduced by 21 kg/t, from 30 to 9 kg/t. INTRODUCTION Processing of sulphide gold-copper ores and concentrates using conventional cyanidation technology results in higher reagent consumption and lower gold recovery. Destruction of sulphide minerals and extraction of copper from a processed product prior to cyanidation is essential for improving efficiency of precious metals recovery and reducing main reagents consumption. Atmospheric oxidation (AO) is one of the most promising hydrometallurgical methods of refractory gold-copper concentrates processing, along with biooxidation and pressure oxidation. The nature of this approach lies in oxidation of sulphides at 90-95°C, in acidic or alkaline conditions, with bubbling of oxygen or air, after preliminary ultrafine grinding (1-4). The following reactions of sulphide oxidation occur during atmospheric oxidation of a gold-copper flotation concentrate. Pyrite is oxidized with the formation of ferric sulphate (1) and elemental sulphur at low temperatures (2), whereas some portion of elemental sulphur reacts to form sulphuric acid: FeS2+3,75O2+0,5H2O=0,5Fe2(SO4)3+0,5H2SO4; ?G=-1144,02 kJ/mol (1)"

Jan 1, 2018

By S. F. Kaplan, A. S. Dolotov, V. N. Kovalev

"The proportion of refractory sulphide ores and concentrates in world gold mining industry is growing every year. Pressure oxidation of these materials (in autoclave) allows to oxidize gold hosting minerals. Traces of halides and pseudohalides present in the slurry liquids contribute to formation of complex gold compounds. Sorption-active carbon present in ores leads to irreversible adsorption of complex gold compounds and their loss. The objective of the research is to study gold extraction dependence on the concentration of chloride-, cyanide- and thiocyanate-ions in the slurry liquids during pressure oxidation. Double refractory flotation concentrate of the Bakyrchik deposit was used for the testwork. The research was planned on the basis of a full factorial experimental design with additional refining experiments. Ligand concentrations (0 – 1000 mg/l Cl-, 0 – 600 mg/l CN-, 0 – 1200 mg/l of SCN-), temperature (200 – 240 °?) and retention time (1 – 6 h) were used as variables of pressure oxidation process. It was determined that sulfide minerals oxidize much faster than ""organic"" carbon. Under the conditions of T = 240 ?C, t = 2 h, sulphide sulfur oxidation was 95.6%, while ""organic"" carbon oxidation was 46.1 %. Each of the examined ligands has a significant adverse impact on gold extraction. Analysis of the experimental data demonstrated that with a high degree of confidence (R2 = 0.883) gold extraction does not depend on the ligand type, but only on its concentration and the ""organic"" carbon oxidation degree. In case of complete oxidation of ""organic"" carbon, the presence of the ligand (L = Cl-, CNS-, CN-) in the liquids at a concentration of up to 20 millimole/L does not significantly affect gold extraction. The assumption that the main factor of preg-robbing in ???-CIL treatment of double refractory concentrates is the natural ""organic"" carbon sorption-active to gold has been confirmed. INTRODUCTION In recent decades, placer gold mining has been gradually declining and hardrock gold mining, including ""refractory"" gold mining, has been growing all over the world, as well as in the Russian Federation (http://www.miningworld.ru, 2015). One of the main reasons why gold ores are refractory is gold adsorption on natural carbonaceous materials (""organic carbon""). Only a few technologies are suitable for processing such ore concentrates (a significant amount of gold is contained in refractory hardrock ore both in Russia and worldwide) (Vorob'yev-Desyatovskiy N.V., Yepifanov A.V., 2014)."

Jan 1, 2018

By Hans-Åke Häggblad, Bertil I. Pålsson, Jan Stener, Kent Tano, Andreas Berggren, Pär Jonsén

Numerical modelling of grinding in tumbling mills is traditionally done with the discrete element method (DEM). The grinding balls are then represented by DEM particles and the mill structure is considered rigid. To include more physical phenomena several numerical methods can be combined. One important improvement is to include the mill structure response, using the finite element method (FEM). The interaction between charge and lining can then be studied in detail. The pulp can also be included using a particle-based continuum method e.g. smoothed particle method (SPH). The strength of SPH lies in modelling of free surface flows and very large deformations and it is suited to model simultaneous fluid and granular flow. Still, the coarse particles (grinding balls) in the charge are suitable to be model using DEM. Each of these methods has their strength and weaknesses, but combined they can successfully mimic the main features of the charge movement. With these numerical tools the complex interaction between the different components of the grinding process; pulp, charge, lining and the mechanical behaviour of the mill, can be studied together. This work will present novel numerical approaches to model, simulate and validate charge behaviour in tumbling mills. These numerical models give possibilities to better understand the physical and mechanical behaviour of particulate material systems during grinding in a tumbling mill. This is important in order to develop and optimise future high-capacity grinding circuits and save energy.

Jan 1, 2014

By Robinson Irarrazabal, Edison Collinao, Rodrigo de Carvalho, Patricio Davila, Marcelo Tavares

"In recent years, DEM (discrete element method) softwares, along with 3D laser measuring equipment, have become powerful tools to describe mill charge behavior, as well as forces acting on the liners of SAG mills. With the aim of contributing to streamline this application of the advanced technologies ME Elecmetal and Universidade Federal do Rio de Janeiro, UFRJ, proposed a new approach to improve the design of mill liners using elements from mechanistic modeling of grinding. The paper presents a methodology for continuous improvement of liner design, which uses information from the DEM collision energy spectra in the mill discriminated for the different components (ore and steel balls), as well as information on the breakage properties of the ore being ground. From these it proposes the concept of "effective collisions", which corresponds to the collisions that are of sufficient magnitude to cause breakage, thus allowing to discriminate from impacts that do not cause breakage either in a first impact or after repeated loading. It also tracks the collision of steel balls against the shell in order to assess their potential damage to the liners. An industrial case study is presented of a 38’ diameter SAG mill, which was experiencing challenges associated to liner breakage and low efficiency with the old liner design. Through a modification of the liner design, simulations demonstrated the potential benefit associated to reduction in ultraprojection and improvement in mill capacity. Implementation of the new design in the SAG mill was carried out, resulting in increase in daily throughput from 6 to 12%. Further, the time spent in liner change was reduced by 47% given the reduction in the numbers of parts. This operation also benefited from having no stops due to unplanned shutdowns to replace broken tiles. These demonstrate the benefit of coupling advanced computational tools to sound engineering principles in continuous improvement of liners."

Jan 1, 2014

By Katarina Theander, Robert J. Pugh

The generation of froth with a critical degree of stability and height is an important aspect of the froth flotation. In this paper we have studied the synergism and anti-synergism in frothing behaviour in a mixed flotation collector/frother mixture (a model fatty acid; sodium oleate and a model frother; nonionic (polyethyleneoxide alkyl C14E6). Values of the collector / frother molecular interaction parameters (the ß-parameters) were determined from the surface tension data using regular solution theory. The frothing characteristics of the system were evaluated using a glass column equipped with a series of conductivity electrodes, which enabled the water content of the froth to be determined. From these measurements, the dynamic frothability and static froth stability were determined. It was concluded that the synergism/anti-synergism in frothability was depended on the molecular composition of the surfactant system, the diffusion of monomer to the thin film interface and on the breakdown of the mixed nonionic/anionic micelles.

Jan 1, 2003

By F. v. d. Meer, G. Kretschmar, T. Mütze, T. Leißner

"Dynamic air classifiers separate particles in a gas flow due to different particle trajectories utilizing differences in the settling velocity of particles as characteristic property for separation. The present contribution takes a close look at the separation of heterogeneous mixtures, in which valuables and gangue minerals show significant differences in density. The focus was on a moist iron ore sample, which was characterized in terms of mineralogy, grain size distribution, and particle size distribution. The material was classified at a cut size of 45 µm and at feed moistures between 0 and 6 wt.-%. Additionally to standard characterization techniques, the moisture of both products was measured as well as the yield of fines as product fraction in a corresponding processing plant. In addition, an automated mineral liberation analysis (MLA) provided information of the enrichment and segregation of individual mineral phases in the products. The MLA of the classification products reveals a selective comminution of the mineral phases and especially on overmilling of the valuables. For the first time, the separation of individual mineral phases has been assessed and compared to the classic assessment of classification processes by means of particle size analyses. KEYWORDS Dynamic classifier, segregation, MLA, selective comminution INTRODUCTION Dynamic air classifiers separate particles in a gas flow due to the different trajectories of the particles. The result of such a separation process depends on the gas throughput of the classifier, the dimensions, design and rotational speed of the deflector wheel, as well as the state of dispersion and thus the geometry of as well as the turbulence and interparticle interactions in the separation zone. Air classification of moist feed materials can be divided into several sub-process (Leschonski, 1977; Mütze et al., 2016): - dosage of the feed material, - dispersing the solid feed material into a gas stream, - feeding the dispersed material into the classification zone by pneumatic conveying, - drying of moist particles during pneumatic conveying, - separation of coarse and fine particles, and - separation of fine particles from gas."

Jan 1, 2018

By Mohammad Kor, David Beattie, Agnieszka Mierczynksa-Vasilev

The selectivity of polymer adsorption in mixed mineral systems is the basis for polymer depression of gangue minerals in flotation. Effective polymer depressants not only reduce gangue mineral recovery, they also have minimal effect on the recovery of the value phase, presumably through targeted adsorption on the gangue phase, and minimal uptake on the value phase. Traditionally, polymer depressant design has been guided by single mineral phase adsorption tests, with affinity and maximum adsorbed amount determined for gangue and value phases separately. However, there is a need to determine the actual extent of adsorption on the gangue phase while in the presence of the value phase. In this work, we report on the development of in situ atomic force microscopy (AFM) imaging for determination of polymer depressant coverage and morphology on mixed mineral surfaces. Our group has previously used AFM imaging on single minerals to connect adsorbed layer characteristics with bubble-particle attachment and flotation outcomes. Two sample types were used to test the methodology: (i) a mixture of two crushed/ground minerals encased in resin; and (ii) a composite mineral sample containing macroscopic regions of three different mineral phases. The samples have been used to probe the selective uptake of two modified dextrin polymers (octenyl succinate anhydride dextrin). AFM images acquired in situ (while all surfaces are immersed in the same polymer solution) of each mineral phase have revealed the natural selectivity of the polymer for the mineral surfaces. In all cases, the polymers adsorb on the all mineral surfaces present, but to a varying extent.

Jan 1, 2014

By S. L. Gao

Based on the differences in hardness and density of diaspore and aluminosilicate minerals which usually exist in Chinese diasporic bauxite, It is analysed that bauxite of this kind is difficult to be separated effectively by classification and normal gravity separation, and cyclonic centrifugal field was thus proposed to be carried out, in which classification can take place according to the size difference resulted from selective grinding, what?s more, the separation function according to density difference is expected to take effect at the same time, and then cyclonic separation tests for diasporic bauxite of A/S 4.39 and grinding 61.90% -0.074mm were carried out tentatively. The results showed that the accretion of feed pressure can offer strong enough centrifugal force for cyclonic separation with result that separation function according to density difference is effectively intensified, by the increasing of this parameter, underflow and overflow of A/S 7.64 and 2.18 can be processed at the same time, and the recovery of Al2O3 in underflow is 71.78%; judging by the flow ratio, the spatial locality envelope of zero vertical velocity do constringe to the vertical axis by the enlarging of diameter ratio of apex to vortex, overflow and underflow of A/S 2.08 and 6.5~7.0 can be processed by controlling this structural parameter, which is possible to offer a technological method for low-grade bauxite to de-sliming beforehand.

Jan 1, 2014

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 Lev Filippov, Lorène Dessalas, Inna Filippova, Yves Foucquet

"Seafloor massive sulphide (SMS) deposits, similar in composition and genesis to terrestrial volcanogenic massive sulphide deposits, are generally found in volcanic seafloor environments along major rifts and mid-ocean ridges. Theyare associated to extensional tectonic settings such as nascent-arc, rifted-arc and back-arc environments. They may represent important source of base metals and be an alternative to on-land resources. Seafloor massive sulphide deposits have particular mineralogical compositions and textural features differentiating them from terrestrial one. When extracted from salty water and exposed to the ambient air, massive sulphide samples strongly oxidize and soon become covered by thin layers of iron, copper and zinc rich sulphates and oxides, as well as elemental sulphur. The textural properties vary according to the degree of maturity and the sample position within the hydrothermal deposit. The total porosity of that type of samples is also relatively high, especially for immature samples such as black smoker chimneys, which can reach 15% of total porosity. Because the secondary mineralization and porosity level are different, seafloor massive sulphides ores respond differently from terrestrial ore to processing methods. Froth flotation, commonly applied to separate all type of sulphides from the gangue, is one possible technique for processing seafloor ore. Sulphide recovery rate is, in most cases, excellent (>90%) however separation of the various mineral phases is difficult to obtain even when applying known methods used for terrestrial ore. Moreover, the flotation behaviour decreases drastically with the time of conservation at the surface, even when the samples were stored in a confined environment. High pH values, which is a good way to depress pyrite and therefore to favour the flotation of copper and zinc sulphides, do not have the same effect on seafloor ore. Consequently, careful flotation procedure must be elaborated to obtain efficient mineral separation technique for this specific marine ores."

Jan 1, 2014

By S. Castro, L. Uribe

Seawater can be considered as a particular process water with a high concentration of NaCl (about 0.5- 0.6 mole/L) and high concentration of hydrolyzing metal cations (mainly, Mg2+ and Ca2+ ions). Micro-flotation tests, induction time measurements, and zeta potential measurements have been used to investigate the effect of these ions on the natural floatability of molybdenite. The results demonstrate that molybdenite is strongly depressed in the alkaline pH range over which hydrolysis products of Mg2+ and Ca2+ ions are formed. At pH 10, colloidal magnesium hydroxide seems to be responsible for molybdenite depression in seawater and in Mg2+ solutions. This is also supported by the measurements of the effect of Mg2+ ions on the zeta potential of molybdenite. The mechanism of depression of molybdenite with Ca2+ ions is different, and depression takes place in the pH range were Ca(OH)+ complexes are formed, below the pH of precipitation of calcium hydroxide. Adsorption of the cationic hydroxy species and/or hetero-coagulation of the positive charged colloidal hydroxide on the negative charged molybdenite particles seem to be the main mechanisms involved.

Jan 1, 2014

By S. P. Nagaeva, O. U. Poperechnikova, A. V. Kuptcova

"In case of free gold presence in ore, there is always problem of a choice between the gravity-flotation and gravity separation flowsheets. Study of morphology of gold being extracted by different methods allows to find the most efficient solution. One of the latest methods of gold concentration for wide range of grain size (-0.8+0 mm) is a flash flotation. The paper presents comparative testing results of flash and centrifugal separation.The goal of the studies was to determine process and flotation parameters of flash flotation. In case valued minerals are soft if compared to host rock, such minerals tend to concentrate into circulating load of grinding circuit. Thus, valued minerals can be overground, and in turn, will result in low extraction in flotation circuit. Integration of flash flotation operation into process flowsheet has been evaluated. Flash flotation operation can be successfully used not only for gold but also copper, lead, nickel and silver minerals.With low-sulphide ores being a case study under laboratory conditions, various flotation (impeller rotational speed, air flowrate) and process (pulp density, collector consumption, frother consumption, time of flotation) parameters were studied in view of its impact on gold flash flotation. Experiments were carried out under laboratory conditions using special pneumatic mechanical flotation machines.INTRODUCTIONGravity separation is used for extraction of coarse gold before cyanidation and before flotation of polymetallic ores to increase gold total recovery into gravity copper and lead concentrates.Benefit of the flash flotation is efficient recovery of coarse gold carrier particles (sulphides) thus preventing its regrinding and, as a result, low recovery. Furthermore, combination of flash and conventional flotation results in final tailings that do not require further cyanidation.Combined gravity-flotation flowsheets are designed for concentration of ores containing gold within thewide range of grain sizes (see Table 1)."

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 Fengming Li, Baocheng Song, Yuemin Zhao, Hailin Dong, Liping Peng, Chusheng Liu, Chenlong Duan

The large-scale vibrating screens with high processing capacity and efficiency are now in great demand in the mineral processing industry of China. However, as the equipment is always suffering from the strong external harmonic exciting force, the inertial force and the impact from the minerals, the fracture of the beam and the crack of the lateral plate are easy to occur, which has a negative effect on the reliability of the equipment itself and the industrial production. Considering the essential high reliability of the equipment, a new large-scale vibrating screen with duplex statically indeterminate mesh beam structure (VSDSIMBS) was developed. The natural characteristics, namely, the natural frequency (or the modal frequencies) and the natural mode, and the dynamic characteristics of the VSDSIMBS were obtained by the modal analysis and the harmonic response analysis. In addition, the dimensions and the constructions of the statically indeterminate plate and the mesh beam were chosen as the design parameters, to which the sensitivity of the whole mass, the maximum deformation and the maximum stress of the duplex statically indeterminate mesh beam structure (DSIMBS) were summarized for the optimization of the DSIMBS. Now the large-scale VSDSIMBS is being well used in China.

Jan 1, 2014

By Kevin Davey, Liza Forbes, Leanne Smith

Given the global scarcity and value of potable water, interest in the use of water of lower quality in mineral processing has grown significantly in recent years. Previous laboratory batch flotation tests conducted at CSIRO have shown that chalcopyrite floats strongly without collector in distilled water and that the collectorless flotability of chalcopyrite is unaffected by the use of brackish water, sea water or hypersaline water. In contrast, bornite is moderately flotable without collector in distilled water but all three lower-quality waters have a detrimental effect on the recovery of bornite. The depressant effect is so strong that the little recovery achieved in these waters was only slightly above what might have been expected from entrainment alone. This work has now been extended to another important copper sulfide mineral, chalcocite. In contrast to chalcopyrite and bornite, chalcocite does not exhibit collectorless flotability so the chalcocite tests in this study were performed in the presence of a standard collector (potassium ethyl xanthate). The results reveal that chalcocite is flotable with xanthate in distilled water but the lower-quality waters have a detrimental effect on the recovery of chalcocite. This effect is partly reversed by increase collector additions. Further tests were completed in order to investigate the effect of the different ions present in the saline waters on chalcocite flotation. Possible reasons for the observed differences are discussed in terms of the pulp chemistry of the system.

Jan 1, 2014

By E. R. Bobicki

"Low-grade ultramafic nickel ores, while representing a large potential nickel resource, are difficult to process due to their serpentine content. Microwave treatment is proposed as a technique to improve the beneficiation of ultramafic nickel ores by converting the constituent serpentine to olivine. The present paper reviews the microwave heating response of ultramafic nickel ores and resultant changes in mineralogy, as well as effects on grinding and slurry rheology. Beyond nickel extraction, microwave treatment improves the mineral carbon storage capacity of ultramafic ore tailings, providing a potential source of additional revenue via the sale of carbon credits. The combined positive effects, considered in the context of the whole operation, suggest an economically viable process is possible.INTRODUCTIONAs high-grade deposits become depleted, the processing of low-grade ores has become increasingly important. One such resource is low-grade ultramafic nickel ores. While representing a large source of nickel, these ores are difficult to process due to their serpentine content. Serpentine is a phyllosilicate mineral consisting of 1:1 stacked sheets of silica tetrahedra and magnesium hydroxide octahedra. There are three primary polymorphs: lizardite (platy), antigorite (corrugated) and chrysotile (coiled, fibrous). The anisotropic nature and non-spherical morphology of serpentine particles leads to complex rheology. Suspensions of serpentine minerals, especially those of chrysotile, exhibit high viscosity and yield stress, which can have a negative effect on comminution, flotation and dewatering operations. In flotation, serpentine is known to slime-coat pentlandite, a valuable nickel mineral, and form bubble-fibre aggregates that report to the froth, reducing nickel concentrate grade and recovery. Methods used to counteract the effects of serpentine in processing include desliming, the addition of chemical dispersants, salts or acid, and dilution (Bobicki et al., 2014a). Microwave pre-treatment has been proposed as an alternative way to eliminate the deleterious effects of serpentine in ultramafic nickel ore processing by converting the serpentine to olivine via dehydroxylation, which occurs at 600-700oC (Reaction 1). Olivine is isotropic, consisting of isolated silica tetrahedra linked by octahedrally coordinated magnesium ions, and has the same surface potential as pentlandite at the pH of flotation (~pH 9). Furthermore, since olivine is more reactive to CO2 than serpentine, microwave pre-treatment creates an opportunity to store more CO2 in tailings, an attractive option for mining operations looking to increase their bottom line where carbon pricing exists."

Jan 1, 2018

By M. A. Naimanbayev, Zh. A. Baltabekova, N. G. Lokhova

"Integrated utilization of natural resources using energy-saving and waste-free technologies is relevant around the world. This applies to such type of raw material as titanium-magnetite ore. Shortage of ilmenite raw materials in the Republic of Kazakhstan for titanium slag melting challenges the search of alternative titanium-containing raw materials, titanomagnetites in particular. At the same time there are deposits of indigenous titanomagnetite ores of huge reserves, which can become the complex raw material for production of iron, titanium and vanadium. Tymlay field in the South-Eastern part of Chu-Ili watershed is of particular interest, within the Karasay ore unit with iron content of 30,4 and titanium dioxide - 10%, and after beneficiation titano-magnetite concentrate contains Fe-52,4; TiO2-of 16,06%. Technology of titanium-magnetite concentrate ore-thermal melting was developed at Tymlay deposit producing hot metal and low titanium slag that can become the raw material for titanium production using chloride method. Slag produced in course of titanomagnetite ore-smelting consists mainly of alumosilicates and sodium silico titanates, magnesium and calcium titanates, titanium dioxide and lower titanium oxides. Following operations were carried out to improve titanium slag quality: slag sintering with sodium hydroxide; cake leaching with water to remove water-soluble impurities; to reduce the number of operations impurities leaching with hydrochloric acid was combined with pyrohydrolysis of titanic acid; rutile concentrate production (85% TiO2, 7,66% SiO2), silica removal by means of sodium hydroxide solution treatment, finally sellable rutile concentrate was produced with titanium dioxide 91-92% and silica 1,7 to 2,0% content. Based on research results technological scheme of titano-magnetite concentrate processing at Tymlay deposit was proposed producing hot metal and certified rutile concentrate, suitable for chlorination."

Jan 1, 2018

By T. Surkova

For the moment reserves of high-grade ores are practically depleted requiring ever-increased involvement of low assay raw materials, such as black-shale ores, in industrial operations. Black-shale ores are constituted of minerals containing such valuable components as vanadium, uranium, molybdenum, manganese, and rare-earth elements (REE). We studied technogenic solutions of black-shale ores processing, after uranium, molybdenum, and vanadium were recovered. Mentioned solutions contain rare-earth elements in substantial quantities (S REE 70-100 mg/dm3) that is very important factor taking into consideration the world demand ever-increasing last years. Higher concentrations of iron and aluminum inhibiting REE sorption and extraction recovery are found in solutions. We propose a method of hydrolytic deposition to cleaning solutions from impurity elements (Fe, Al). Study of hydrolytic deposition kinetics allowed identifying optimal conditions to run this process. Rare-earth elements may be recovered from purified solutions through sorption process followed by their further deposition from eluates in form of concentrates. Keywords: black-shale ores, rare-earth elements, a method of hydrolytic deposition, impurity elements, sorption

Sep 1, 2012

By M. C. Harris

"In the flotation process the contact angle is an important indicator of the hydrophobicity of a mineral particle. There is considerable literature showing that the contact angle increases when the chain length of the alkyl group associated with the collector molecule used to render the valuable mineral particle hydrophobic increases. The extent to which an alkyl group interacts with surrounding water molecules is quantified thermodynamically by the excess Gibbs energy. In the present paper it is shown that there exists generally a strong linear relationship between the excess Gibbs energy of the alkyl group associated with the collector and the contact angle. The structure-activity of such alkyl groups is in turn related to the total surface area, molecular volume, the molar volume, molecular weight of the functional groups in the molecule and interaction energies. It is proposed that the demonstrated relationship is indicative of the role which the alkyl group component of the collector, which is attached to the mineral particle, plays in increasing the extent to which water molecules at the surface of the mineral are rejected from the surface thus increasing the contact angle. The relationship between excess Gibbs energy and surface tension is further explored with a view to relating the observations quantitatively to the parameters in the Young equation.INTRODUCTIONThe issue of wettability of materials is of great importance to many industrial applications. Wettability studies usually involve the measurement of contact angles which indicate the degree of wetting when a solid and liquid interact. As is well known the contact angle (O) is the angle between planes tangent to the surfaces of the solid and the liquid at the wetting perimeter which is the zone where the air, water and solid phase merge. When the air bubble attaches to the solid surface there is an increase in the air/solid interface area and a decrease in the solid/water interface area. For attachment to occur the cosine of the contact angle should be less than 1 and this will be promoted if the interfacial surface tension between the air and the solid (? SV) is low. Classically the relationship between these parameters has been expressed through the Young equation (1) for a perfectly flat surface:"

Jan 1, 2018