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By Kazutoshi Haga, Batnasan Altansukh, Atsushi Shibayama

Results of flotation process combined with atmospheric leaching and high pressure leaching for recovery of copper from low-grade silicate-copper ore have been presented in this study. The low-grade copper ore contains a small amount of copper (0.42 mass %), iron (4.6 mass %), and silicon (38.3 mass%) and among many other metals (Al, Ca, K, Mg, Na, Ti and S). The main mineralogical constituents of the copper ore are calcium aluminosilicate (Ca(Al2Si2O8), amesite (Mg2Al2SiO5(OH)4) and gypsum (CaSO4×H2O), and quartz (SiO2) as resulted from the alteration of an igneous rock. This study has shown that about 92 % of copper can be recovered with a maximum copper grade of 4.2 mass% in a froth after 15 minutes of flotation at pH 8.5 when used potassium amyl xanthate as a collector, MIBC and Dow-froth 250 as frothers and calcium hydroxide as a pH adjuster. The images of bubbles in the cell during flotation process were recorded using a high-speed camera. The froth concentrate with average copper grade of 2.0 mass% was further processed by atmospheric leaching with a solution of sulphuric acid and hydrochloric acid, respectively and high pressure leaching with sulphuric acid solution. As a result, leaching rate of copper reached about 60 % in an atmospheric leaching with sulphuric and hydrochloric acid respectively, whereas the rate can reach more than 70 % by autoclave leaching at high pressure under the controlled condition. A process to recover of copper from its low-grade ore can be developed by optimization of flotation combined with acid leaching.

Jan 1, 2014

By Shuji Owada, Mayumi Ito, Takehiko Nishimura, Toru Yamashita, Sadayuki Shinozaki, Takashi Ando, Tomoe Ota

Electrical disintegration (ED) was applied to Nantun coal (China) in order to improve liberation of coal substance for the pretreatment of producing “Hyper Coal” of which the combustion gas was planning to inject directly to turbine for power generation. It has been found that many cracks generated in the ED were existent at phase boundaries with mineral matters and liberation of coal substance became much higher than that in mechanical comminution methods such as roll crusher. Since the ED occurred more easily (with lower voltage applied) for the coals of higher mineral content, it is considered that this method could make a better contribution especially to comminute middling coals. We also found that the ED technique could apply not only single particles but also to coal particles assemblage, keeping almost the same or higher disintegration efficiency. In the mineral matters, Si and Al components were preferentially well liberated by the ED.

Jan 1, 2003

By E. V. Manlapig, M. C. Harris

"The complexity of the flotation process has made the identification of an appropriate model structure for the predictive simulation of flotation circuits far from obvious. Work performed under the auspices of the AMIRA P9 flotation program has indicated that the metallurgical performance achieved from a flotation cell arises from the interaction of two essentially independent property classes, namely the cell operating conditions and the properties of the cell feed stream. These observations have led to the development of a model structure that associates a constant set of flotation parameters to the streams of the circuit, which are transformed into a flotation response depending on the operating conditions within the flotation cell.A variety of alternative model structures exist within the literature which do not make this distinction between cell and stream flotation properties, and many of these models are in widespread use for flotation optimisation and design studies, both in industry and academia.In this paper, circuit survey and laboratory batch flotation data collected from an industrial flotation circuit are analysed. The data demonstrate that streams in an industrial flotation circuit exhibit varying particle floatability – concentrate streams typically float faster than tailing streams (Figure 1(a)). This floatability, however, is generally conserved around the various units within the flotation process (i.e. the effective floatability of the combined feed and product streams of a unit is equivalent (Figure 1(b)))."

Jan 1, 2003

By Avishan Atrafi

Frothing behavior of surfactants originate from their preferential adsorption at the gas-solution interface. Different surfactants may demonstrate different adsorption behaviors depending on their molecular structure and surface activity. The quantity and rate of adsorption of surfactants at the gas- solution interface in flotation systems will certainly affect kinetics of reaction and fractionation of surfactant between bulk and foam phase and subsequently their frothing characteristics. In this paper, the frothing characteristics of sodium oleate which is the main constituent of fatty acids used in flotation systems is explained. The adsorption behavior of sodium oleate is then compared to a typical non-ionic frother (Methyl Isobutyl Carbinol, MIBC) in terms of different adsorption behavior at the gas-solution interface. Since long chain fatty acids are weak electrolytes, their behavior is a strong function of pH. Also semi soluble salts including apatite contain considerable amounts of ions like calcium in their lattice, so the effect of presence of ions on the frothing behavior of fatty acids requires an investigation. A mass balance on the surfactant transferred to the foam was solved to estimate the bubble surface area flux in foam, which explained how the adsorbed surfactant at gas-solution interface controls the bubble surface area flux at foam. Since sodium oleate adsorption at foam takes place gradually, frother concentration as a function of time was monitored by the total organic carbon measurement (TOC) to compare the surfactant uptake rate at different concentrations, pH and ionic strength. The surfactant concentration adsorbed within foam together with the value of adsorption density from the Gibbs adsorption, leads to the calculation of the surface area flux and prediction of average bubble size in the foam at a specific time frame. This value was compared at different concentrations of sodium oleate. Dynamic surface tension measurements were accompanied to explain the adsorption behavior, though finally equilibrium surface tension turns out to better explain the foamability characteristics. Keywords: flotation collectors, flotation froths, foams, fatty acids, adsorption behavior

Sep 1, 2012

The multiphase reactive flow in process equipments, e.g., fluidized beds, involves complex coupling among flow, heat/mass transfer and reaction kinetics over scales ranging from molecules, sub-particle eddies up to equipments. Conventional two-fluid model (TFM) ignores the effects of meso-scale structures, and hence is not suitable for describing the intrinsically multi-scale heterogeneity within multiphase systems. To be consistent with the meso-scale structures, we proposed a structure-dependent multi-fluid model (SFM), and closed its drag force by invoking the stability condition defined in the energy-minimization multi-scale (EMMS) model. The SFM reduces to the conventional TFM if homogeneous distribution is assumed within each grid, and reverts to the original EMMS model if it is used to describe steady state, global behavior of a fluidized bed. The multi-scale computational fluid dynamics (CFD), which is characterized by coupling of TFM and EMMS drag coefficient, can then be viewed as a simplified solution of the SFM. We demonstrate that the SFM significantly improves the accuracy and at the same time enables higher efficiency by allowing for much coarser grid used than in TFM. Recent application of it in 3D, full-loop, transient simulation of industrial processes, e.g., fluid catalytic cracking, coal combustion, gasification, kaolinite clay calcinations, shows its advantages in helping design and troubleshoot multiphase process equipments. Keywords: meso-scale, SFM, multiscale, CFD, simulation, structure, EMMS, multiphase

Sep 1, 2012

By D. G. Hulbert

"Mineral processes are complex operations that have been modelled, controlled and simulated by diverse technologies. A review is given of some models of mineral processes in the literature. A new variation of a dynamic process model of flotation is presented. Process models, describing real and relevant physical variables, give a good understanding and good qualitative simulations, but can sometimes require prohibitively difficult and extensive parameter estimations. Process control is usually best done on operational plants by the fitting of system models, which can home in on the plant?s observability, controllability and optimisation. System models can be of a form amenable for use in appropriate techniques for controller design and implementation. The control of milling circuits is discussed in some detail. While simulators use models to predict dynamic or steady-state information, part of their strength lies in their ease of use and their ability to test different types of specifications. Some results are given for a flotation circuit simulator that can be made to solve virtually any permutation of specifications.INTRODUCTIONThe development and application of appropriate technology can lead to better operation of mineral processing plants in industry, so that substantial benefits can be obtained from improved throughputs, efficiencies and product qualities. This paper addresses some of the principles and methods used in the quest for the development and exploitation of such technology. Although the design of processes is often the motivation for modelling and simulation, this paper also targets the use of modelling and simulation for the control and optimum operation of mineral processes. The two processes given the most attention here are flotation and milling.Technologies used in mineral processing range from simple to very complex. Simple technical principles, such as mass and component balances, can yield some simple and effective strategies for modelling and control. However, minerals in particulate form have such complex physical and chemical properties that there appears no end to the complexity that emerges, as more and more factors are taken into consideration in the pursuit of better results and understanding. The situation is aggravated by the complexity of mineral processing plants, which have spatially variable conditions within process units, and complicated interactions between these units."

Jan 1, 2003

By P. Saha, D. M. Chakrabarti, National Metallurgical Laboratory, P. Bhattacharyya, B. R. Sarkhel

The estimated reserve of the phosphatic soils at the Sukulu hills region of Uganda upto a depth of 60 meters is of the order of 200 million tonnes and analyses 10-12% P2O5. A 5-tonne sample of the phosphatic soil was received at the National Metallurgical Laboratory (NML), India for beneficiation studies. The ore occurred as a naturally degraded soil deposit and the slime contained earthy lateritic minerals which made it extremely sticky. Microscopic examination revealed the presence of limonite, magnetite (martitised), hematite and goethite as major minerals along with apatite and quartz. Presence of clay was indicated by earthy smell on moistening the sample. It was observed that getting rid of the slime was as important for adequate beneficiation of the ore, as it was difficult. Earlier studies on samples of the same ore at the NML and abroad established that it was necessary to pass the ore through a series of three stages of desliming, each consisting of a step of rigorous attrition scrubbing followed by hydrocycloning, for effective elimination of the sticky slimy coating which stubbornly adhered to mineral grains. Studies were carried out at the NML in two phases to develop a flowsheet for beneficiation of the phosphatic soil. In the first phase, reproducibility of the results obtained by employing a flowsheet developed abroad was confirmed along with suggesting some modifications of the flowsheet. Then 200 kg. of concentrate was produced following the recommended flowsheet for evaluation of its suitability for production of fertilisers. To remove the limonitic slimy coating, which stubbornly adheres to the other mineral grains, it was necessary to subject the ROM ore, after screening out the +840 micron size fraction which contained only 1.75% P2O5 , to three stages of hydrocycloning each preceded by attrition scrubbing. Then only conventional beneficiation techniques could be effectively employed to upgrade the ore.

Jan 1, 2003

By R. C. Miranda

This paper intends to demonstrate the applicability of tools for advanced process control and online particle size image analysis in crushing and autogenous grinding circuits. In a crushing plant, cameras are installed in the conveyor belts of the circuit products. The vision system continuously processes the acquired images and thus obtains the variation of the size distribution curve. From these measurements, the advanced control system can operate, for example, at the opening of the crusher, in order to keep the P80 in the desired range. In addition, through the power information and level of the crusher's chamber, it is possible to increase the capacity of the crushing circuit. If the crusher is not equipped with an automatic opening adjustment, a warning may be issued to the operator to provide this setting manually. In mineral processes that use autogenous and semi-autogenous grinding for fragmentation, obtaining online F80 through the vision system allows for manipulating the parameters of rotation speed and solids concentration, through which the amount of material at the critical particle size that is produced can be controlled. In addition, the noise produced in the mill can be measured and controlled. Thus, it is possible to prevent breaches and to optimise the mill capacity for grinding. Image analysis combined with an expert system that translates this information and acts to seek the most appropriate particle size distribution, brings greater stability to the process optimising the capacity of the equipment, which allows for significant gains in production.

Sep 1, 2012

By P. Somasundaran, G. Anastassakis, Z. Pan, D. R. Nagaraj

Gums are often used as depressants for talceous gangue minerals in the flotation of nickel and platinum bearing ores. However, the mechanisms of gum adsorption on talc are not clearly established. In this work, adsorption of guar gum at the talc-solution interface is investigated using spectroscopic and allied techniques. Guar gum adsorption on talc is not affected significantly by changes in solution conditions such as pH and ionic strength. Electrokinetic studies showed that guar gum decreased the negative zeta potential of talc but did not reverse the charge. Fluorescence spectroscopy studies conducted to investigate the role of hydrophobic bonding using pyrene and dansyl probes showed no evidence of the formation of hydrophobic domains at talc-aqueous interface. Urea, a hydrogen bond breaker, reduced the adsorption of guar on talc to the same extent as that for guar/alumina system, in which hydrogen bond plays an important role. All of the above results suggest that one of the main driving forces for guar adsorption on talc is hydrogen bonding rather than electrostatic or hydrophobic force.

Jan 1, 2003

By Tasuma Suzuki

Electrokinetic/permeable reactive barrier system is a promising in situ soil and ground water remediation technique to reduce toxic NO3- into less toxic NH4+. Using granular zero-valent iron (Fe0) as a reductant, the first objective of this study was to investigate the influence of the solid-liquid ratio and aqueouspHon NO3- reduction. The results obtained from a series of batch experiments showed that NO3- reduction was enhanced by either increasing solid-liquid ratio or decreasing aqueous pH. Based on insights obtained from batch experiments, the second objective of this study was set to design the remediation conditions of the electrokinetic/Fe0permeable reactive barrier system to maximize the NO3- reduction efficiency. Experimental results showed that the effectiveness of the system strongly depended on the Fe0 percentage in the reactive barrier, the pH in the anode reservoir, and the applied voltage, which were consistent with the results obtained from batch experiments. Under optimized treatment conditions, nearly 100 % NO3-was reduced into NH4+ in the permeable reactive barrier and collected in the cathode reservoir. Insights obtained from this study provided fundamental information on roles each of remediation design parameters plays, and will be useful to optimize the remediation conditions. Keywords: electrokinetic remediation, permeable reactive barrier, zero-valent iron, nitrate

Sep 1, 2012

By M. Ito

The authors have developed the RETAC jig (a modified TACUB jig) and have reported that the RETAC jig can separate relatively low density particles such as plastics. To further improve the separation ability, a hybrid jig (a RETAC jig with an air bubbler under the particle bed), which can separate plastics having similar specific gravities by the differences in the wettabilities of the particles was developed. Surface modification of plastics with similar wettability enabling separation in the hybrid jig and the effects of wettability control of the plastics using reagents are reported.

Sep 1, 2012

By D. Saramak

Investigations over the application of hybrid comminution circuits with the High-Pressure Grinding Rolls (HPGR), on the main comminution stage on the basis of the lime and cement industry, were presented in the paper. Two crushing circuits were investigated, the first HPGR-based and the other one, with conventional jaw crusher. The results presented in the article confirm that hybrid comminution circuits with the application of HPGR are innovative ones, and they assure achieving the technological and economic competitiveness in the mineral raw materials processing industry. They are much more favorable in terms of the final product fineness and capacity but insignificantly less effective about the unit energy consumption. Technological performance of conventional crushing circuit and HPGR-based one were also compared in lab scale. The circuit with HPGR application gives finer products both on crushing and grinding stages. The average particle size reduction obtained in HPGR-based circuit is as much as twice greater, comparing to the conventional crushing devices. Keywords: comminution, HPGR technology

Sep 1, 2012

By Kyle Bartholomew, Robert McIvor

"Functional performance analysis of closed circuit grinding provides valuable insight into the two components of ball mill circuit grinding efficiency: classification system efficiency and mill grinding efficiency. Classification system efficiency isolates the combined effect of classifier performance and circulating load ratio from other circuit variables, such as ore grindability and the mill grinding environment. Optimization of classification system efficiency ensures grinding energy is applied to particles needing further size reduction and not to overgrinding. Entirely based on size distribution data, classification system efficiency precisely distinguishes subtle changes in classification system performance. Use of the functional performance equation to isolate mill grinding efficiency allows for proper optimization of the mill grinding environment by isolating confounding effects of changes in classification and ore grindability. Variables such as mill percent solids and grinding media selection can be optimized using the mill grinding efficiency subcomponent of functional performance. First published by McIvor in 1988, the functional performance equation provides a set of standardized, quantitative optimization criteria, simple and powerful, which link circuit performance to plant design and operating variables that can be manipulated. Functional performance optimization has been applied in numerous mineral processing plants globally and continues to gain acceptance as a practical means for grinding circuit optimization. In this paper, examples of derivation and industrial application demonstrate the means by which functional performance analysis dissects grinding circuit efficiency into its subcomponents allowing the reader to apply this straightforward, powerful optimization methodology at their mineral processing operation."

Jan 1, 2014

By A. Kuriwada

Dolomite is a mineral, which consists of CaCO3 and MgCO3. In this work, a series of experiments were carried out in order to adsorb boron from a boron-containing solution using a calcinated dolomite sample, and then to desorb it from the loaded adsorbent. A particular modification on the surface of dolomite was observed when it was thermally treated at certain temperature, ranging from 750 oC to 1050 oC; in turn, it is the specific surface was increased. In other words, the experimental results suggested that the calcinated dolomite exhibited a high adsorption capacity for boron, indicating its effectiveness in effectively adsorbing boron from drinking water or wastewater.

Sep 1, 2012

By Olli Haavisto, Heikki Häkkänen, Tommi Kauppinen, Navid Khajehzadeh

Raman analysis is a well-established method for finding the abundant minerals in an ore sample. In this study, Raman spectroscopy is tested as a method for rapid and contactless on-line mineral analysis. Rapidness might enable on-site analysis of rock drillcore, which in turn would lead to more cost-efficient solutions in mineral exploration. This paper discusses the use of Raman analysis to identify minerals and to measure their concentration. The sample set under study consists of rock drillcore collected from Agnico-Eagle Kittilä Mine, Finland. Selected parts of the sample set are measured by Raman spectroscopy and the minerals are identified using reference spectra from a public source. Moreover, the direct measurement of concentration of different minerals with the help of Non-negative least squares (NNLS) optimisation algorithm is considered. The optimisation algorithm was constructed to form a linear combination of reference spectra which best represent the measured spectrum, or an average of measured spectra, from an ore sample. The results show that NNLS can identify abundant minerals in a given sample. Also through this method of analysis the results of a traditional point-count method can be expanded: It was observed that, due to grain size, multiple minerals consistently appear in the spectra measured over an area, which means that point-count method is not a proper way to interpret the spectra. This can be seen as a new result, as formerly the discussion has attended to other methods.

Jan 1, 2014

By M. Brennan, A. Majumder

"The mineral processing research community has devoted enormous efforts to the modelling of mineral separators over the last 50 years. While many efforts have been made to use only fundamental physics as a basis for the models, fluid flow patterns in separators are not simple while the motion of particle swarms through fluids is extremely complex.One of the simplest separators is the sluice, in which separation takes place in a flowing film a few millimetres thick. The particles are suspended by turbulent eddies and motion relative to the fluid takes place in so-called hindered settling mode.In an effort to test the extent to which fundamental fluid mechanics can provide a prediction of particle separation, a study on a simple parallel-sided sluice has been carried out using glass beads at various particle concentrations and flow rates.The actual particle separation taking place was compared to predictions made by first describing the fluid flow by a modified ‘law of the wall’ model.Particle concentration distributions were described using Hunt’s sediment transport model, assuming the particle eddy diffusion coefficient to be the same as that for the water. Settling velocities were calculated using either the Richardson and Zaki or Brauer and Thiele models. The latter takes into account particle size and density distributions and solids volumetric concentration.The resulting predictions of particle separation are remarkably good, even though the model does not model the local settling velocity in the slurry."

Jan 1, 2003

By Ashok M. Raichur, S. P. Vijayalakshmi

"Recent advances in technology and the growing environmental concern have laid emphasis on the usage of fine clean coal. Coal fines are also generated in large amounts during various coal processing operations and are difficult to be treated, handled and disposed. Since most of the operations use water as the carrying medium, the fines so generated contain lot of moisture. Conventional technique for processing coal fines includes flocculation by a polymeric reagent followed by moisture removal using a rotary drum or a pressure plate filter, which produce a product with more than 30% moisture. Polymeric flocculants though required in small amounts, need high shear mixing for good performance and operate only in a narrow pH range. Moreover they increase the viscosity of the solution by many folds. Hence it becomes imperative to emulate newer methods for efficient fine coal processing. One such method is the novel use of microorganisms in coal processing.The present investigation deals with the utilization of two gram-positive microorganisms, Mycobacterium phlei and Bacillus subtilis, as bio flocculants and dewatering aids in fine coal processing. Preliminary characterization done on J-coal and M.phlei showed that they are negatively charged over most of the pH range. B.subtilis was found to possess positive charge below pH 4.7. The adhesion studies proved the high potential of microorganisms for adsorption to surfaces. Adhesion tests were conducted at various experimental conditions by varying parameters like pH and ionic strength of the suspension. Results obtained showed that adhesion is always higher in the presence of an electrolyte like KNO3 and most of the adhesion takes place in 15 minutes. With change in pH the amount of B.subtilis adhering on to J-coal remained almost constant and for M.phlei it decreased at higher pH values. Increase in ionic strength did not increase the adhesion of bacteria. Flocculation experiments confirmed the ability of the bacteria to act as bio flocculants. It was seen that about 98% of the coal settled in about 2 minutes on the addition of bacteria along with the addition of the electrolyte. The electrolyte was found to be indispensable for efficient flocculation of the coal suspension and for the attainment of a clear supernatant after flocculation. Also the optical micrographs revealed the formation of large, tight flocs when the electrolyte is present along with the bacteria. Further, flocculation tests were done in the pH range of 2-10 and the flocculation efficiency was found to be independent of pH."

Jan 1, 2003

By Ersin Yazici, Ahmet Bas, Haci Deveci

Pregnant leach solutions from waste of printed circuit boards (WPCB) leaching contain many impurity metals (Fe in particular) at significant levels. These impurities should be reduced to acceptable levels to avoid problems in downstream recovery processes e.g., low current efficiencies in electro-winning of copper from sulfate solutions in the presence of ferric. In this study, removal of iron in the form of goethite from synthetic (30 g/L Cu2+ and 1 M SO42-) and real leach solutions of WPCB was studied in some detail. The influences of initial concentration of iron (1-4.5 g/L Fe3+), pH (2.5-4.0), temperature (80-90°C) and seeding (23.5 g/L) were investigated over a period of 4 h. A significant increase in the iron precipitation was observed (i.e., from 68% to 96% over 4 h) with rising the pH from 2.5 to 4.0. The addition of seeds had also increased the removal rate over 4 h albeit to a limited extent i.e., from 96% to 99%. For the real leach solutions of sulfate (H2SO4-H2O2) and sulfate/chloride leaching (H2SO4-CuSO4-NaCl), precipitation of iron was found to be 63-73% (pH 2.5) and 93-98% (pH 4.0), respectively. The precipitates were further characterised by SEM-EDS analysis which showed the presence of copper (1-25%) in the precipitates indicating significant copper co-precipitation from the solution. These copper losses can be attributed to the formation of copper compounds such as anthlerite and brochantite within the range of pH (2.5-4.0) tested. This study showed that iron can be readily removed from synthetic/real leach solutions of WPCBs to a large extent (=93%) at the expense of high copper losses particularly at pH 4.0.

Jan 1, 2014

By Christopher M. Rule, Martyn P. Hay

"A methodology was developed in the mid-1980’s to predict plant performance from standard laboratory flotation tests. The methodology incorporates a flotation simulation program “SUPASIM” which translates flotation performance from bench-scale tests to full-scale plant. The technique is based on a simple, empirical kinetics model, and is tailored for use by the practical metallurgist. Kelsall’s unmodified equation incorporating two rate terms describing slow and fast floating components is used as the basis of the method. The flotation behaviour of an ore is described by a set of numbers, which can be compared in the evaluation of ore types, mineralogy and operating conditions. In so doing a precise relationship is developed between metallurgical performance in terms of grade and recovery and flotation kinetics.To date the performance of more than 20 flotation plants has been predicted, encompassing copper, lead, zinc, nickel, phosphate, pyrite, graphite, cassiterite, platinum and various slags. In three cases, plants have treated more than one type of ore. The method has successfully been used to predict and design four flotation plants using data generated from bench-scale laboratory flotation testwork. All have since been commissioned, and have performed as predicted. In the last year alone it has been used to drive flowsheet development for at least seven new plants in South Africa and the Americas. It is also being used to assist in the optimisation of existing operating plants."

Jan 1, 2003

By Alexey P. Tatarinov

Under modern economic conditions in Russia, gold heap leaching is the most effective way of investing into gold-mining industry. Gold is recoverable from small-size deposits, low-grade ores from oxidation zone, cut-off grades, and overburden rocks using heap leaching. This technology is cost-effective and allows a saleable metal to be obtained within the first year of operation. The investments for heap leaching are lower than those of for a traditional plant technology. Production cost per one gram of Au is 5-7 times lower than that of during a plant flow sheet. A seasonal development of mines can be possible. With reference to this, heap leaching resembles the technology of placer deposits development. One of the major advantages of heap leaching is the form of the product. Gold can be obtained as dissolved in a clarified PLS, which allows the further quick treatment. The amenability of ores to heap leaching depends on their mineralogical composition. Oxidized porous ores with a good access of a lixiviant to valuable particles can be treated without pre-crushing. Clayish minerals are often found in oxidized ores with free gold. In order to build ground for heap, several major methods combined with various pad materials are used. These methods have been used at many plants and are reliable. The development of heap leaching technology for gold ores for the deposits from Yakutia, Zabaikalsky region, Primorye region, Uzbekistan, Tadjikistan, and Kazakhstan began in the 70s. However, it has been commercially used only since 1990. The first heap leach plants were built and commissioned in the USSR in 1991 at Vassilkovsloye deposit (Kazakhstan) and at Maiskoye deposit in Russia in 1994. Pilot plant testing was conducted in 1996 using ores from Kuranakh ore field, deposits Phiskulturnaya-Kholodnaya and Lopukhovskoye from the Aldan region. After the first successful commissioning of heap leaching plant in Russia, this technology has been commercially applied for deposits. Every year 1-2 heap-leaching plants were commissioned. More than 30 heap-leaching plants have been commissioned both in Russia and in the former Soviet Union using technologies developed by IRGIREDMET. Keywords: cyanide leaching, heap leaching, ore, percolation, solutions, lime technology

Sep 1, 2012