Search Documents

By Andrew T. McBride, Malcolm S. Powell, Indresan Govender

"Current empirical Semi Autogneous Grinding (SAG) mill models contain assumptions concerning the amount of energy available for particle breakage, how this energy is distributed in the mill media and the rate at which the energy is transferred. Despite these assumptions the JK SAG model is highly functional with a proven track record. DEM provides a numerical framework to greatly improve on these assumptions that were necessary due to a lack of available input data.This paper identifies key outputs of the Discrete Element Method (DEM), such as energy spectra and impact probability distribution. It describes how they can be incorporated into current mill models utilising practical rock breakage data. The rate at which energy is transferred is shown to be dependent on particle position and mill rotational speed and not once per cycle as previously assumed. Based upon this an improved energy transfer methodology is presented. The fundamental outputs of the DEM are validated against experimental three-dimensional particle tracking data, so as to establish whether the DEM produces correct energy transfer predictions on the inter-particle level, which is crucial to this work."

Jan 1, 2003

By Wantae Kim, Hoon Lee, Kwanho Kim, Sangbae Kim

Mechanochemical activation of starting minerals and their effect on the solid-phase synthesis and properties of ceramics with lower thermal expansion coefficient was examined. The mineral mixture, pyrophyllite-gibbsite-lithium carbonate, was prepared for the synthesis of ?-eucryptite (Li2O•Al2O3•2SiO2). Dry grinding using a planetary ball mill promoted the amorphization of the starting mixtures. XRD and FT-IR results showed that the crystallization of the target materials occurred from the ground mixtures by calcination. The crystallization of them increased with increment of grinding time and calcination temperature. In the synthesis, the trace of undesired phases such as quartz and cristobalite once formed during calcination at the temperature range from 750 to 850 °C almost disappeared and monophase ?-eucryptite was formed in the ground mixture at 950 °C. The lowest liner thermal expansion coefficient (TEC) of ?-eucryptite prepared was -2.5x10-6•°C-1. The thermal expansion behavior characteristics of the calcined

Jan 1, 2014

By H. J. Schulze

From a colloidal science point of view (Schulze 1984, Nguyen & Schulze, 2004) five micro-processes are responsible for successful particle-bubble formation: the approaching of the particle to the liquid-air interface, the thinning and rupture of the intervening liquid film, the expansion of the three phase contact perimeter, the generation of sufficient large capillary force to stabilise the aggregates and the transport process of particles into and within the froth layer. Flotation reagents influence mainly the thinning and rupture of the intervening liquid film between particles and air bubbles, the expansion of the three phase contact after the rupture of the liquid film and the stability of the aggregates against external destruction forces in the flow field. But it exist also a non-negligible influence on the approaching of particles to the bubble surface during the encounter process and on their passing over into the froth layer and the froth stability.

Jan 1, 2003

By Lj. D. Andric

By the micronization-milling of the material, the size and the structure of its particles are changed and it comes to the increasing of the potential energy of the system as well as to the chem-ical activity of the material what is the result of an increased free surface and of the concentration of the grate defects, that is of the internal energy of the system. All these changes that are reached, show that new characteristics of treated materials are got by micronization process. Controlling the process of the micronization and by purpose directing of the new characteristics of the activated materials, we can have the positive effects and use them in more technologies. Talc is important nonmetallic mineral raw material that is widely used as either the basic raw material, or as filler. This has stimulated its technological investigation, as well as the investigation of its physical-chemical characteristics. In this paper are shown experimentally reached results of the physical-chemical characteristics of the talc during the process of the micronization in high energetic mill. In this paper, the optimum conditions of miconization of talc in high-energy-speed rotary mill and its influence micronization on a degree of Fe2O3recovery by hydrometallurgical methodes, are presented. The X-ray analysis of the obtained products showed that high quality talc with low content of can be obtained by these physical-chemical processes In this paper, the principles and application or fine and ultra-fine grinding high-energy attriton mill with small balls, enabling fast, efficient grinding, low energy consumption, short grinding time and easy handling will be described.

Jan 1, 2014

By William Skinner, Jennifer MacCarthy, Jonas Addai-Mensah, Ataollah Nosrati

"Acid leaching in agitated tanks is central to hydrometallurgical processing for valuable metals’ (e.g., copper, gold, nickel and cobalt) recovery from low grade (e.g., < 2 wt.%) ores. In this study, atmospheric leaching behaviour of Australian saprolitic nickel (Ni) laterite ore using sulfuric acid was investigated under isothermal, batch conditions at pH 1. The effect of primary process variables comprising time (4 h) and temperature (70 and 95 oC) on the leaching mechanisms and kinetics was established for -2 mm, low grade (~1 % Ni) saprolitic ore dispersions at 40 wt.% solid loading. Leaching proceeded incongruently, reflecting the proliferation of gangue minerals’ constituent elements (e.g., Mg, Al, Fe) alongside Ni and Co in the pregnant leach solutions (PLS). Subsequent analysis showed that 89% Ni and 78% Co were extracted after 4 h at 95 oC whilst at 70 oC the recoveries of these metals were markedly low (< 25 %). Overall, 177 and 644 kg H2SO4 /t dry ore were consumed at 70 and 95 oC, respectively. Activation energy of 79.0 ±1.0 kJ/mol was estimated for the mechanism of Ni and Co leaching and associated kinetics. Particles size analyses indicated that when the breakage of frail laterite particles due to shear is taken into consideration, differences in feed and leached product particle size distributions were insignificant , despite a remarkable increase in BET specific surface area of the product. Mineralogical analyses of the feed ore and leached solid products revealed a sub-crystalline silica phase enrichment of the latter. The overall results suggest that the mechanism of acid leaching of saprolitic Ni laterite may be described by a chemical reaction-controlled, shrinking core model."

Jan 1, 2014

By Luis Bergh, Juan Yianatos, Luis Vinnett

"Process automation as an engineering discipline is more than control systems since it includes industrial instrumentation, such as sensors, transmitters and actuators, as well as control and supervision systems, collection and transmission of data and real-time software applications to supervise and control the operation of plants or industrial processes. In the last several decades, accelerated technological development has provided a variety of software and hardware tools to aid development, maintenance and continuous improvement of automated systems. These developments however seldom reach their full potential in real plants. There are many factors to be considered, among them human capital specific training and the organization model. In this paper, a methodology for training engineers in advanced control and supervision of flotation plants is presented based on study of the application of these technologies in hybrid pilot plants. Since experimentation in real plants may present undesirable risks and costs, and simulation studies are usually limited to some unrealistic conditions, a laboratory where on-line measurements of the hydrodynamic behaviour of a pilot plant is mixed with phenomenological models has been created. In this form, an environment as close as possible to a real plant can be recreated. A flotation column and a circuit of three pneumatic cells are fully instrumented and connected to a PLC and PC network. In the control room, students learn applications of classical PID control in a DCS environment, advanced predictive control, on-line process operation diagnosis, fault analysis, virtual sensors and expert-fuzzy systems. Several undergraduate and graduate courses and theses are supported by this Process Control Laboratory infrastructure. Examples of these applications are discussed."

Jan 1, 2014

By A. D. Ramirez, L. E. Gutierrez, M. A. Garces

"Scarcity of freshwater in mining operations in arid zones in different parts of the world has led to the mining companies to think about using seawater as an alternative source in mineral processing operations. Examples of this situation are Minera Centinela (AMSA) and Minera Sierra Gorda (KGHM), both plants located in northern Chile. Previous studies showed that molybdenite flotation is depressed at high pH values in seawater as a result of the action of hydroxy-complexes of magnesium and calcium that attach to the faces of the molybdenite particles, reducing its hydrophobicity and as a result flotation recovery. In this work, a study of the interactions between molybdenite and kaolinite is presented. The effect of sodium hexametaphosphate (SHMP) dispersant on the recovery of molybdenite in the presence of kaolinite is studied in different aqueous media and it is correlated with induction time data. The results allow to conclude that kaolinite has a stronger depressing effect on molybdenite in seawater compared to its effect in freshwater. Magnesium and calcium are the cations that have the strongest effect in enhancing the interactions between molybdenite and kaolinite. SHMP reduces the negative effect of kaolinite on the floatability of molybdenite both in seawater and freshwater. The induction time data correlate well with the micro-flotation results.INTRODUCTION The need for water in mining processes in arid and semi-arid zones has led to the search for new alternatives for this resource, among which seawater has gained an important space. In Chile, most of the mining operations are located in the northern part of the country, an area that has limited availability of freshwater for the processing of copper and molybdenum sulfides (Castro and Laskowski, 2011, Castro et al., 2012 a). Seawater is an aqueous solution with high concentrations of ions such as Na+, K+, Mg2+, Ca2+, So42-, Cl-, and other less concentrated species which generate important effects in the flotation process as they modify the properties of the solid/liquid, and liquid/gas interfaces, and also increase the consumption of some important reagents used to depress pyrite such as lime. It has also been proposed that flotation of copper sulfides is negatively affected in seawater because of the reduction of oxygen solubility compared to freshwater (Millero et al., 2002; Duan and Sun, 2003). In contrast, it has been shown that the presence of ions in solution in the process of flotation of natural hydrophobic resources improve recovery as result of the compression of the electric double layer (Laskowski, 1974; Klassen and Mokrousov, 1963, Laskowski and Castro, 2008."

Jan 1, 2018

By A. P. Purgin, M. G. Viduetsky, I. F. Garifulin

"The combined treatment process for mine, tailings storage facility, quarry, circulating, and waste water in the mining and metals industry brings together the conventional chemical treatment processes and pneumatic flotation cells of the KFM series. The key principle of the process is preparing the water for treatment by saturating with finely dispersed air bubbles in the flotation cell blowers. Gas-air lift dispersers located in the lower part of the cell body additionally saturate the cell’s contents with finely dispersed air. Due to the residual content of flotation agents in the treated water, hydroxide ion-air aggregates form at the aerator outlet, supporting the efficient precipitation of hydroxide ions of heavy non-ferrous metals, calcium and magnesium ions. This process was tested in the pilot plant KFM-180 with a raw (untreated) water capacity of up to 18 m3/h per 1 m3 of the flotation cell volume using a mixture of the tailings storage facility and mine water from JSC Safyanovo Copper. The treatment process included raw water treatment with lime, aeration in KFM cells, and filtration in a sorbent bed. The content of metal ions in the treated water is lower than in the feed water by a factor of up to 170,000 and approaches the standards: aluminum 0.016-0.02 mg/l, copper 0.0043-0.0045 mg/l, zinc 0.049-0.052 mg/l. circulating water of Soryin Tailings Storage Facility at JSC Svyatogor. The treatment process included raw water treatment with lime and alkali, aeration in KFM cells, and filtration in a sorbent bed. The content of metals in the treated water is lower than in the feed water by a factor of up to 9000: copper 0.022 mg/l, zinc 0.012 mg/l, iron 0.012 mg/l, manganese 0.015 mg/l, nickel 0.132 mg/l, arsenic 0.016 mg/l. Water hardness is significantly lower: calcium - 12.6 mg/l, magnesium - 1.1 mg/l. This process can be used in the treatment of mine, quarry, tailings storage facility, and circulating water at mining and non-ferrous metals projects."

Jan 1, 2018

By Andrzej Luszczkiewicz, Aleksandra Potulska

"Flotation is a basic process of beneficiation of mineral raw materials which requires very fine grinding for liberation of valuable minerals. Probably flotation will also play this role in the future. In the case of flotation of difficult-to-upgrade non-ferrous ores, currently one of the most important trends in technology development is solution to fine grinding even down to a few micrometers in size and elaboration of effective flotation technology for such fine particles. Both industrial flotation data and many investigators suggest that the best results of flotation of ore minerals are observed for particle size range from 20 to 100 µm. Many base metal ores require grinding below 20, or even 10 µm, to liberate valuable ore components. However, industrial flotation of particles below 20 µm in size creates numerous challenges. Further complications may be caused by a complex nature of the ore, especially when the valuable metals are present in several different sulfide minerals. This problem occurs in the case of the Polish sedimentary copper ores. In the present study, flotation of the ore of different size distributions and degrees of grinding, having the size of particles below 25 µm, was investigated. The behavior of different sulfide minerals naturally present in the ore was analyzed. The best results of flotation tests were obtained for the ore ground down to 95% below 25 µm. Narrow size fractions -10; 10-15; 15-25; 25-40, and +40 µm were separated using special micro-sieves and mineralogical as well as chemical analyses of each size fraction were carried out for monitoring the behavior of the fine sulfide particles. Differences between flotation of chalcocite-digenite, bornite, chalcopyrite, covellite, galena and pyrite-marcasite naturally occurring in the ore were described. The role of different particle sizes in flotation performance of each mineral was also presented."

Jan 1, 2014

By Mojtaba Ghorbannezhad, Abbas Sam, Soroush Arabzadeh

One of the dewatering methods in mineral processing plant is filtration system. Disk filters are included the porous surface with pressure drop on both sides, Water in the pulp passes through the surface and solid particles remain as a cake on it. Wet concentrate production of magnetite processing plant at Golgohar Mining and Industrial Company with solid tonnage of 160 ton per hour and 49% solid amount contains 166 m3/h of water. In the present study, in addition to studying disc filter performance, the effective parameters on cake moisture were studied using Vacuum Bottom-Feed Leaf method (in the laboratory scale). Optimization was performed using the Taguchi method. The results showed that the cake moisture is reduced by increasing particle size and solid percentage (because of specific resistivity reduction), while the rate of cake formation and its thickness are increased. Also, it was found that by increasing pressure, the cake moisture is reduced and cake formation rate and its thickness are increased. In this study, the effect of fabric texture was also examined. Lowest cake moisture was obtained in condition of using compressed plain fabric with mono-multi filament fibres, pressure at 75kPa, solid percentage of 65 to 70, particle size (D80) equivalent to 123µm and disk rotation speed of 1.25 rpm.

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 Daniel Saramak

"Issues concerning effectiveness of the high-pressure comminution process in technological circuits of copper ore treatment were presented in the paper. Crushing processes taking place in high-pressure grinding rolls devices (HPGR) are currently one of the most efficient methods of hard ore size reduction in terms of the energy consumption. The HPGR products are characterized by a fine particle size and the micro-cracks formation in individual particles, which appear in downstream grinding processes, decreasing their energy consumption. The purpose of this paper was to analyse the effectiveness of a ball mill grinding process depending on the changeable conditions of run for the HPGR crushing process. The research programme carried out included crushing tests in the laboratory scale HPGR device at various settings of the operating pressure volume and selected qualitative properties of the feed material (i.e. particle size distribution). Particle size distribution analyses of all HPGR products were performed and in the next stage the material was a feed to the ball mill grinding process. Grinding process kinetics were investigated through the determination of mass recoveries of individual particle size fractions after defined grinding time intervals. The models, defining the grinding process effectiveness as a function of changeable conditions of HPGR process run, were determined on the basis of obtained results. Based on these models the optimal grinding time in a ball mill was specified which is, in turn, the basis for optimization of operation of the technological comminution circuits for a given material type. The obtained results proved that the application of HPGR devices in a given copper ore comminution circuit may improve the effectiveness of the downstream grinding process which leads to improvement of the entire circuit work efficiency through decreasing the process energy consumption and enhancing product size reduction."

Jan 1, 2014

By Weiran Zuo, Emmy Manlapig, Fengnian Shi

The effect of metalliferous grains on electrical comminution efficiency was investigated by comparative experiments using natural rocks and synthetic samples. The result indicated that the existence of metalliferous grains affects the breakage probability and product size distribution of electrical comminution. On average, metalliferous grains increased the breakage probability of particle in the first pulse discharge by 55% and generated finer product at the coarse end. As a result, particles with metalliferous grains exhibited higher energy efficiency than that without metalliferous grain in electrical comminution. A positive linear relation between product fineness and specific energy in electrical comminution was observed. With the assistance of numerical simulation on the electrical field distribution of ore particle, the role of metalliferous grains in electrical comminution is confirmed and the mechanism of metalliferous grains effect is elucidated. Understanding of the effect of metalliferous grains on electrical comminution is important to evaluate the feasibility of applying electrical comminution to ores with different mineral composition, and to understand the breakage behavior in electrical comminution.

Jan 1, 2014

By Diego Mesa, Willy Kracht

Frothers may be classified as weak or strong depending on their ability to produce stable froths, which is related to the amount of water that they transfer from the pulp to the froth. They can also have an effect on the non-selective mechanism of recovery by entrainment, implying that both selectivity and froth stability are, at least to some extent, frother dependent. Solids, on the other hand, also have an effect on froth behaviour. Clays, which are characterized by their small particle size, laminar shape, and high specific surface, tend to report to the froth phase and have an enormous impact on both froth stability and the overall performance of the flotation process. The purpose of this work is to shed light on the effect that different frothers have on the froth behaviour when clays are present. In order to do that, two sets of experiments were conducted using frothers from the families of alcohols and polyglycols. For each test, the equilibrium froth height was measured at different frother concentrations in an agitated machine with an acrylic square-base cell that was 11 cm wide and 25 cm high. The cell was designed in such a way that froth was able to grow without concentrate discharge. In the first set of tests, pure clays such as kaolinite and montmorillonite were used. In the second set, an actual copper sulphide ore with a high content of clays was used as solid phase. The results, expressed as curves of equilibrium froth height against frother dosage, showed a coupled effect of frother-clay on froth behaviour for both sets of experiments. In some cases, the froth grew up until the border of the cell with only a few parts per million of frother. In other cases, the equilibrium froth height varied smoothly with frother dosage. The results suggest that choosing the right frother can be of use for controlling the froth behaviour when dealing with clay-rich froths, using frother dosage as the control variable. The application of these findings at industrial scale are discussed and some recommendations are given.

Jan 1, 2018

By L. A. Nemchinova, M. A. Arustamian

"For a long time tailings piles of mining and smelting complexes have met the eye being a prospecting feedstock source for many industries. Nowadays, 6.5 million tons of copper and cooper-zinc processing tailings are stockpiled in the Urals annually, as there is no technology of its processing to provide a full and complex metal extraction within mining and processing operations. In spite of large volumes of mining wastes, not more than 20% of annual overburden, approx. 10% of processing wastes, approx. 40% slags (1) are involved into processing.Based on today’s complex of economic, environmental and social challenges of ore processing, waste processing technology using existing capacities is a burning issue. Mining wastes characteristics (including fine dissemination, variability of physical and chemical properties of mineral surfaces under impact of oxidizing, leaching, etc.) predetermine challenges arising out of its involving into processing and justify high capital intensity of new construction or reconstruction projects followed by replacement of existing processing lines with new ones.In this paper, the authors propose flotation technology for mature tailings of copper, copper-zinc and polymetallic ore processing. The technology developed provides for upgrade of existing process flowsheet diagrams at minimum costs to produce additional saleable products including low-grade copper concentrate, saleable zinc concentrate and gold concentrate thus facilitates sustainable use of depleting minerals and operational efficiency due to cost-efficient processing of already mined materials, being in fact, final semi-products located near existing operations. This is particularly important for operations with standby capacities and not engaged workforce."

Jan 1, 2018

By Jacques Eksteen, Sharif Jahanshahi, Neill J. Bartie, Shouyi Sun

The gradual increase in Cr2O3 levels of UG-2 ores has become a matter of concern for platinum producers in South Africa due to the formation of chromite spinels in melters. The effect of bulk FeOx/MgO ratio, Cr2O3, temperature and oxygen partial pressure on phase stability and composition in the system FeOx-MgO-SiO2-Cr2O3-Al2O3-CaO has been studied between 1400°C and 1600°C using the drop-quench technique. An increase in temperature was found to result in a decrease in [Fe/Cr]spinel. This effect is shown in Figure 1 for the six slag compositions investigated.

Jan 1, 2003

By Przybycien Krzysztof, Tumidajski Tadeusz

"Materials being the feed to mineral dressing plants are the mixture of ore minerals having different physicochemical properties among others, especially susceptibility on crumbling. During exploitation of material and their preparation to communition the big number of narrow classes comes into being and they have different properties. The determination of common communition laws of multicomponent (on account of size and mineralogy) materials leads to the estimation of mutual influence of narrow classes and their rates, taking into account their endurance and mineral density, on general ratios and their simultaneous crumbling.If we try to accept the grain membership to the certain component as the differing feature, we can write the balance equation as: ( ) ( ) S= = k i i i g x p f x1where: fi – density functions of one type distribution and of different statistical moments (characterising the homogeneous materials grinding), pi – “stirring” proportions of each components, S== k i i p 1 1 . From the point of verification view of detailed versions of this equation the inverse operation should be done: in the base of the components’ mixture grinding results and the results of components grinding the legitimacy of equation should be checked.The using of finished distribution mixtures’ theories to the grinding process analysis allows, first of all, to verify the assumption of grinding independence of individual feed components. Talking more generally it would lead to the comparison of grain size distributions, obtained by individual components grinding from the defined in the mixture distributions theory calculations. One of experimental and calculation results for artificial mixtures of galena and dolomite is presented on figure below (df means distribution function)"

Jan 1, 2003

By Irena Grigorova

"Vermiculite is a naturally occurring mineral compound composed of shiny flakes, resembling mica. Worldwide, vermiculite has been used in various industries since 1920. When heated to a high temperature, flakes of vermiculite expand several times their original size. The expanded vermiculite is a lightweight, fire-resistant, absorbent, and odorless material. These properties allow vermiculite to be used to make numerous products, as an additive, for example to potting soil, in agricultural, construction, horticultural and industrial applications, including pesticides, insulation, potting mixes, brake pads, sound deadening materials, fire protection, paints, sealants, insulating concrete and etc. Over recent years researchers have been looking for effective economic and environmental methods and solutions for fine technological waste utilization. As a result of vermiculite ore processing large quantities of fine waste dust are formed. Until now there has been no application for this waste product. Currently this waste product is stockpiled using valuable land space, and is a potential contaminant. The paper presents the results of a study on the possibility to obtain briquettes from fine vermiculite by-product. The particle size distributions, chemical and mineralogical compositions of vermiculite were determined. It was established that consolidation of vermiculite dust by methods of briquetting and its consequent application in agriculture as meliorants for physico-chemical treatment, improves soils aeration structure and properties."

Jan 1, 2014

By M. Kanuchová, J. Briancin, M. Achimovicová

"Faculty of Mining, Ecology, Process Control and Geotechnology, Technical University, Košice, Slovakia An industrial eccentric vibratory mill was used for direct and short-time mechanochemical reduction of ilmenite concentrate (FeTiO3) and anatase (TiO2) with magnesium metal powder in order to reduce Fe and Ti resp. and hereby to convert them to the more soluble phases suitable for further hydrometallurgical processing. X-ray diffraction analysis of FeTiO3 after 60 min of milling with Mg confirmed the presence of Fe0 and Mg2TiO4 phases and for TiO2 after 180 min of milling the new TiO and MgO phases have appeared. X-ray photoelectron spectroscopy has detected Fe0 (metal) and Mg2+ species which are corresponding to the product of FeTiO3 mechanochemical reduction. The product of TiO2 mechanochemical reduction has revealed XPS spectral lines corresponding to Ti2+, Ti4+ and Mg2+ species on its surface. Morphology of mechanochemically reduced samples was studied by scanning electron microscopy analysis. Subsequent leaching of mechanochemically reduced FeTiO3 and TiO2 was performed in dilute HCl and H2SO4 at 80oC and compared with mechanically activated samples. The recovery of Ti has reached 100% for FeTiO3 and 79% for TiO2 after 60 min of leaching. Based on this study the flowsheet for possible processing of natural refractory titanium ores patented by author was adapted and documented. INTRODUCTION Ilmenite (FeTiO3), along with rutile (TiO2) represents the most important titanium resource necessary for titanium industry, for production of titanium metal, alloys and pigment grade TiO2 which are becoming more important and versatile for various industries such as an aircraft and aerospace, navy, chemical, automotive, medical and offshore wind industries, for machine and plant engineering and architecture as well, mainly due to high corrosion resistance. Pigment grade TiO2 is utilizing in pigment, plastic, glass, paper and rubber industries (Zhang, 2011). There are obvious research efforts for development of the potential alternatives to the expensive thermo-chemical commercial processes of titanium raw materials processing. Zhang (2011) has summarized conventional thermo- a electrochemical processes which involved a combination of pyrometallurgical, hydrometallurgical and electrometallurgical technologies and highlighted the improved hydrometallurgical routes promising for commercial application in the future. Such improvement could also be mechanical activation of FeTiO3, TiO2 by high-energy milling which causes their structural disordering, the changes of physical and chemical properties, consequently and has a positive effect on the dissolution kinetics (Achimovicová et al., 2014a, 2017, Baláž, 2008). The various types of mills such as a planetary ball mill, a vertical ball mill, a drum mill, an attritor were used for mechanical activation of FeTiO3 as a pretreatment process for subsequent leaching (Achimovicová et al., 2014)."

Jan 1, 2018

By Matveyeva Tamara

The main deposits of gold-sulfide ores of Russia are characterized as refractory raw material with the non-uniform finely-interspersed sulfide mineralization, submicron gold, the low gold content (3-5 ppm) and non-uniform distribution of the gold associated with pyrite and arsenopyrite. These ores show low indicators of extraction of gold and silver at cyanidation. Flotation is one of the basic technological procedures of processing of gold sulfide ores however simultaneous presence of pyrite and arsenopyrite and lack of effective methods of their selection constrains application possibility of flotation schemes because of rigid requirements to flotation concentrates under the arsenic content and practically excludes smelting of pyrite concentrate. The main losses of precious metals at flotation technologically are concentrated in thin classes (up to 15 %) demonstrating an inefficiency of standard reagent modes. For an estimation of expediency and possibility of application of selective flotation of pyrite and arsenopyrite a scientific substantiation of the mechanism and criteria of selection of gold-bearing ferrous sulfides of various material structure is developed and for difficultly divided pairs of sulfides with close technological properties the new selective reagents providing effective extraction of gold from hard-to-beneficiate ores are designed. The original technique for modifying surface composition of natural sulfides by nano-sized Au is worked out and the mechanism of selective adsorption of new reagents ? oxypropyl ester of diethyl-dithiocarbamatic acid (OPDTC) and oak bark extract (OBE) on Au-bearing sulfide minerals is revealed. Formation of almost insoluble OPDTC-Au compounds is defined by methods of scanning electronic microscopy (SEM) and UV-spectroscopy. Application of developed reagent modes using new reagents have been tested in laboratory conditions at flotation gold-sulfide ores samples and collective concentrate probes providing high extraction of gold and improved quality of the concentrate (less than 2 % As). Keywords: pyrite, arsenopyrite, selective flotation, flotation reagents adsorption, complex-forming, gold recovery.

Sep 1, 2012