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By Janne Kytökari

Controlling a wide range of minerals processes with single control system is an ordinary way to operate in mines all over the world these days. However the potential of these systems is not yet fully recognized nor utilized. The key issue is to manage the information in a way that enables automating the day-to-day tasks, quality control and safety functions. At the same time it provides means for optimization and constant improvement of processes creating a working environment where the system helps employees to do their key tasks instead of searching, modifying, and transmitting the huge number of information arising every day. The distribution of control system nodes enables the other processes to run heedless of a problem occurring in one of the sub-processes. Also the control room can be in remote location such as in large city removing the need to travel substantially long distances to plant sites every day. When all essential information is brought to the same place there is less risk for a mishap to happen due to information breaks that are often the cause of them. One of the biggest single reasons that result in production losses are break downs of machinery usually caused by normal wear, misuse, incorrect utilization rate etc. For this reason it is important to measure the condition of machines using vibration measurement and diagnostics. By moving from failure or time-based maintenance towards predictive or performance maintenance generates eventually a steady and predictable process but also results in significant long term savings. The mineral process at Talvivaara mine is based on bioheapleaching, whereby metals are leached from ore as a result of bacterial action. Bioleaching is a fairly new technology used in metals recovery. Therefore it is important for the mine to collect and analyze data from different stages of the minerals process. Talvivaara mine?s Metso DNA system has integrated machine condition monitoring and information management. These are not only necessary but also crucial in environmental conditions where the outside temperature can drop below -35°C, where ice and snow dominate the landscape and impact the equipment for four months a year and where distances between equipment can be up to 7.5 kilometers. Keywords: DCS, analyzer, machine condition monitoring, automation, remote communications, optimization, mining, metso DNA, Talvivaara

Sep 1, 2012

By N. I. Tyushkova

This is a brief survey of the technological solutions for deep cleaning of baddeleyite?s concen-trate. Baddeleyite is part of kamaphorite of composite apatite-magnetite ore in alkaline-ultrabasic mountain range of Kola Peninsula. Baddeleyite?s concentrate, which is being produced by Kovdorsky GOK (ore mining and processing enterprise) contains 97.5%~98.5% (Zr?2 + ?f?2) and also scandium oxide (0.05%). It is usually used without any chemical processing. World demand for zirconium oxide is constantly on the rise. Its consumption grows in ceramic industry and in high-tech spheres. That?s why the demand for its purity is very important nowadays (additional cleaning from phosphorus, silicon, iron, aluminium). The mechanism and kinetics of interaction of activated bad-deleyite with sulphuric acid has been studied as well. While applying method of mathematical mod-eling it was confirmed that the mechanical activation is effective for the intensification of sulphation process of baddeleyite?s concentrate with the aim of purifying it from dirt. The use of the calculated optimal regimes allows to reduce such technological operation factors as: temperature, the du-ration of process, the sulphuric acid consumption. It also allows to determine the conditions of anticipatory abstraction of scandium and main dirt in solution in comparison with zirconium oxide.

Jan 1, 2014

By Bern Klein, Givemore Sakuhuni, Libin Tong

The use of continuous discharge centrifugal concentrators introduced in the early 1990’s for recovery of gold associated with sulphides has introduced a novel application niche for gravity concentration which could not be realized with the low mass yield batch and semi-continuous concentrators. A typical application is scavenging gold associated with sulphides from flotation tails which has potential to increase productivity by reducing gold loss to tailings and lower grinding cost by using a coarser grind. However, the full potential of this technology has not been fully exploited partly due to the lack of reliable small sample procedures to demonstrate applicability. This paper introduces a bench-scale procedure developed to characterize the Knelson Continuous Variable Discharge concentrator (CVD) for scavenging gold from flotation tails. The procedure code named gravity release analysis was derived from standard flotation release analysis. It is a modification of the gravity recoverable gold and gravity amenability test in order to best simulate continuous centrifugal concentration. Based on this iterative procedure, a gravity release index similar to the flotation rate constant, for measuring individual mineral gravity susceptibility for an ore is introduced which can be a useful quantitative measure to both predict application of centrifugal concentration and for plant design. The gravity release analysis procedure was tested on a polymetallic flotation plant tailing at Myra Falls, BC, Canada and results show that it can predict CVD performance. The gravity release index for gold was observed to decrease with each successive cleaner stage showing that the initial stages recover liberated gold whilst successive runs recover gold associated with sulphides and or gangue. The difference in magnitude of the gravity release index for different mineral species shows the species separable by centrifugal concentration.

Jan 1, 2014

By C. Abbruzzese, F. Vegliò, S. Ubaldini, R. Massidda

"Gold solubilised during cyanidation can be recovered by precipitation (Merrill-Crow process) or by adsorption onto activated carbon, these being the techniques applied in industrial plants.Precious metals (Au, Ag) adsorbed onto activated carbon are extracted during a subsequent stage in aqueous phase, by various technologies, such as hot elution (70-80°C) or under pression desorption (100-130°), with hydro-alcoholic solutions.This stage is of great interest from an economic point of view, due to the high energy costs. Temperature represents the critical kinetic factor.The aim of this paper was to study the influence of different water/organic solvent mixtures (isopropyl alcohol, ethanol and ethylene glycol) on the desorption process.The experimental work was carried out on laboratory scale, using activated coconut carbon with different temperatures and extraction times, without adding cyanide.Best results have been obtained in this order: isopropyl alcohol > ethylene glycol > ethanol. Starting from gold concentration of about 5 g Au per kg of carbon, best kinetics resulted in 97-100% of gold extraction, after 8 hours of desorption, at a temperature of 80ºC."

Jan 1, 2003

By Gerke Gilian, Pretz Thomas, Pehlken Alexandra

"The evaluation of health hazards within the treatment of mineral and waste materials is gaining more and more importance in industrial countries. The need to control occupational health and safety has been recognised, and regulations which describe general protective measurements for personnel provide a tool to protect their health. It is the aim of the paper to give an outlook for practical approaches to risk assessment and to present measures for exposure reduction in accordance with the state of the art in Germany.Both the treatment of minerals and of waste materials are described in relation to the risk assessment. The method of evaluating health hazards in the two industries is similar and therefore both examples are presented next to each other.The example presented in the paper is the German “Biostoffverordnung” (the regulation for biological materials) which is important for the waste treatment industry. All kinds of waste treatment facilities (like composting facilities, waste dumps, sorting facilities for packaging materials) are obliged to carry out an assessment of health hazards for a variety of working areas and working places. The possible safety requirements deriving from this regulation are presented and discussed under the aspect of biological hazards."

Jan 1, 2003

Taknar polymetal (Cu-Zn-Au-Ag-Pb) deposit and concentration flotation plant are located in the northeast of Iran. The flotation feed contains Chalcopyrite, sphalerite and pyrite with 4, 4 and 8 percent respectively. Cu and Zn contents are 1.26 and 3.5 present. Pyrite decreases the quality of base metal concentrates and increases the amount of sulfur compounds produced in the base metal extraction processes. Therefore, depression of pyrite is essential in the concentration of base metal sulfides by flotation. For flotation tests, 4 mixed collector systems, MIBC (20g/t), lime and tow depression systems (sodium cyanide (60g/t)-zinc sulphate and dextrin (300g/t)-zinc sulphate) were used as collector, frother, pH regulator and pyrite-sphalerite depressants in the chalcopyrite flotation stage, respectively, and SIPX, MIBC, lime and copper sulphate (as activator) were used in sphalerite flotation from first stage tailings. The results have shown that, sodium cyanide is a suitable depressant for pyrite and sphalerite in the first stage of flotation. Compared to dextrin as depressant, chalcopyrite recovery was decreased approximately 1.83%. In addition, when sodium cyanide was used as pyrite depressant, copper sulphate consumption raised approximately 90 g/t for activation of sphalerite. From Environment and HSE points of view, dextrin is natural, biodegradable, and non-toxic while cyanide is very high toxic. Keywords: sequential flotation, Cu-Zn massive sulphide, pyrite depressant, dextrin, cyanide

Sep 1, 2012

By V. V. Morozov, Ganbaatar Zorigt, Delgerbat Lodoy, Y. P. Morozov

"At the processing plant Erdenet, a new facility for advanced ore diagnostics in-stream (at the conveyor), based on optical analyser of mineral composition, was tested. Such systems provide highly accurate in-stream measurements of ore properties. The system provided information on the ore mineralogical composition, the particle size distribution and the impregnation of minerals. A special flatbed facility for optical spectrum-based estimation of fine-crushed ore has been developed, being incorporated into the existing system of ore sampling and analysis. Application of the flatbed facility renders possible a high accuracy of determining ore mineralogical composition. High precision of the optical spectrum-based estimation is achieved using special devices, installed in the sampling and the sample analysis flow sheet, applied by the technical control department. Modern systems for optical spectrum-based estimation of ore grade provide a basis for effective automated control of ore benefication processes, based on the principle of advanced ore grade control. Process management task of grinding and flotation was to choose options that take into account the composition and grade of the ore coming. The calculation data array comprises consumption of reagents, ore processing, grind size etc. The systems implemented at the processing plant contributed to increasing copper and molybdenum recovery. INTRODUCTION In-stream ore grade analysis is a new trend in effective control of ore benefication processes. This is realised based on radiometric measurements in the X-ray and visible spectrum regions, in which mineral components of the initial ore (Sbárbaro and Villar, 2010) or the benefication products become apparent (Hyotyniemi and Ylinen, 1998; Haavisto and Hyötyniemi, 2010). An important advantage of such methods is in-stream measuring ore parameters, including mass fractions of individual minerals, which makes it possible to use the information obtained in the processes of automated control."

Jan 1, 2018

By Lilong Huang, Yuan Long, Li Shi, Guowang Zhang, Xiao Xiao

"Graphite is the key raw material of new carbon materials such as graphene and spherical graphite. The size and completeness of graphite flakes directly affect the performance of new carbonaceous materials.The research aims to increase the yield of large flake graphite by way of preventing the flake graphite from being damaged during the grinding process. A series of grinding and flotation studies on the flake graphite samples of Yichang in Hubei Province were carried out by vertical stirred mill . The damage coefficient L characterising the degree of graphite flake fractured and corresponding formula was proposed to determine the quality of the grinding and grinding of the flake graphite. The way the damage coefficient L of graphite flake would be affected if with different mill, different media material and size, stirrer speed were investigated. The test results show that vertical screw stirred mill helps the protection of large flake of graphite as well as the graphite liberation. When grinding to the same fineness, the damage coefficient L of graphite flake is 1.20 for vertical stirred mill, while the damage coefficient is 2.93 for ball mill. Minimum damage coefficient of graphite flake was obtained when using 6 mm polyurethane coated ball as grinding media, under the condition that rotation speed of the stirrer within the range of 100~130r/min. The grade of graphite in the concentrate floated from the ground product was 94.16%, the rate of recovery for graphite was 94.66%, and the content of +0.15mm was 54.83%.1 INTRODUCTION Flake graphite is a very important non-metallic mineral[1,2],and due to its special flake structure, the greater the scale and the higher the C grade, the value of its application is larger too. Therefore, in the grinding of graphite sorting process, We should minimize the destruction of graphite scales.. In this paper, graphite mine in Yichang, Hubei Province was used as the raw material for the study. Rough concentrate with C-grade of 36.49% was prepared by rough grinding and coarse separation. Then a series of grinding and flotation studies on the rough concentrate were carried out by vertical stirred mill , which aims to increase the yield of large flake graphite and to provide technical support for improving the beneficiation process of graphite ore."

Jan 1, 2018

By Vasily V. Lodeischikov, Adolf F. Panchenko, Olga D. Khmelnitskaya, Vladimir E. Dementyev

Pilot plant tests of underground gold leaching from Maminskoye deposit oxide ores at a grade of 0,7 g/t Au were carried out. The underground leaching flow sheet includes Au dissolution by chlorine-containing solutions, Au adsorption from solution on active carbon, carbon concentrate ashing and calcine melting to produce high grade gold concentrate. The underground leaching system throughput was 15 m3 of solution per hour. Gold concentration in pregnant solutions was 0.12-0.13 mg/l. Gold recovery from solutions into carbon was in the range of 63-84%. It was demonstrated that the low Au recovery in the adsorption cycle was due to the presence in pregnant solutions of "active" chlorine, which destroys active carbon and causes a sharp decrease of the carbon loading capacity for gold. To improve the adsorption indices, previously dechlorinated pregnant solutions using bituminous coal or Na2S2O3, is recommended. Ion exchange process was tested as an alternative for gold extraction from dechlorinated solutions. In the testwork period, 4.4 kg of gold were produced with a chlorine consumption of 3.5 kg per 1 g of gold. During the tests a program of environmental protection measures was completed to provide the necessary safety precautions of the underground leaching works.

Jan 1, 2003

By V. A. Chanturiya

The state-of-the-art of mineral mining and metallurgy industry in Russia is characterized by high demand of nonferrous, rare, rare earth metals, and highgrade coal, on the one hand, and by involvement of natural and technogenic minerals with low content of valuable components, fine (nearly emulsion) dissemination of valuable components and close physicochemical and process properties. This calls for high-productive and ecology-friendly technologies for more efficient mineral beneficiation based on intensification of operating and new methods to extract valuable components from rebellious ore and technogenic minerals, relying on the last achievements of basic sciences, combination of dressing and chemico-metallurgical processes and using advanced pyro- and hydrometallurgical technologies. The transition to a new strategy of processing is only possible based on the new technological–mineralogical appraisal of a mineral raw material. Actually, the process mineralogy has a stock of modern high-resolution physical methods for analyzing composition, structure and properties of geomaterials, inclusive of micro- and nano-levels: - Identification of micro- and nano-size noble metals, and natural and induced formations on mineral surface; - Experimental validation of structural phase and chemical transformation of minerals under different energy input; - Justification of choice and mechanism of interaction between flotation agents and noble metals with complex material constitution; - Analysis of structural, phase and chemical transformations of sulfides and rocks under leaching. Thus, process mineralogy is an informational background for a unified theoretical approach to scientific justification of flowsheets of efficient mineral processing. The article gives a brief review of practices that have found application and proved to be of high economic efficiency. Such practices are: X-ray radiometry and photometry separation (Uchalinsky and Gaisky Mining and Processing Integrated Works of ALROSA); selective disintegration (equipment engineered by Mekhanobr-Tekhnika and IPKON RAS); process selectivity enhancement (IPKON RAS, Central Research Institute for Geological Exploration of Nonferrous and Noble Metals, Chinakal Institute of Mining, Siberian Branch RAS, etc.); bacterial gold leaching (Olimpiada MPIW, technologies developed the Central Research Institute for Geological Exploration of Nonferrous and Noble Metals, Nezhdaninsky deposit projects, etc.); combination processing at a mining and metallurgy plant (Norilsk Mining and Metallurgical Company, Yaregsky deposit projects and others); processing of waste: overburden, mill tailings, slag, etc. (Kovdorsky MPIW, Svyatogor JSC, Ural Mining and Metallurgical Company, plants designed by the Central Research Institute for Geological Exploration of Nonferrous and Noble Metals, Mining Institute of Kola Science Center RAS, Research Institute for Chemical Technologies); water conditioning in mineral dressing circuits (ALROSA, equipment by IPKON, etc.); utilization of process water (ALROSA, Ural Mining and Metallurgical Company, Severalmaz JSC and others). Thus, Russia this time has the academic and engineering background for development of efficient energy-saving technologies for comprehensive advanced processing in accordance with the world’s standards, or even higher in terms of a number of the technologies, which has continually been highlighted by participants of recent international congresses on mineral processing.

Jan 1, 2018

By G. Unland

The sizing of crushers depends on the expected crushing forces. However, the crushing forces develop differently with every individual rock while it is compressed by the working surfaces of the crusher. For sizing, this compression process has to be characterized by the maximum crushing force. The maximum crushing force depends on the strength, shape and size of the rock, the amount and velocity of the imposed displacement of the working surfaces of the crusher on the rock and the conditions of the contact surfaces. From experience it is known that the strength of the material and, therefore, the crushing forces depend on the size of the specimen. This dependence is the so called size effect. The determination is based on compression tests. The force development is recorded during the compression of the specimen and for every individual test the maximum force is determined. The occurring maximum crushing forces of several rocks with the same diameter comminuted under the same conditions can be assessed by a mean value and a variance. The relationship between the mean values of the cross section related maximum crushing forces FAmax and the corresponding sizes d of the specimens can then be described by mathematical functions. They are derived from different approaches (phenomenological, statistical and statistical-physical methods). The phenomenological methods are subjective and yield functions depending on the assumptions of a person, whereas the statistical and statistical-physical methods are based on an evaluated function and the optimization of the parameters.

Jan 1, 2014

By Peter Kondos

The need for a sustainable development of ore deposits makes it imperative to be innovative and mindful in creating an economically and environmentally viable operation, while maintaining a good working relationship with the various stakeholders involved in developing and operating a large and complex mining project. This is becoming immensely important as gold ore deposits are becoming more mineralogically complex along with lower grades presenting both metallurgical and environmental challenges that need to be addressed in mitigating risks and improving project economics. This paper presents Barrick?s approach to development of strategic technologies for our long-term sustainable growth through conversion of valuable resources into reserves for both our green-field development projects and the expansion of our existing mining operations. Some of the key strategic solutions, including mineral processing, metallurgical and energy technologies, developed by Barrick and their impact on some of our complex gold and copper-gold ores will also be discussed in this paper. Keywords: gold ores, copper-gold ores, processing, breakthrough technologies

Sep 1, 2012

By J. Yianatos, C. Matamoros, F. Díaz

The non-selective entrainment of fine solids in flotation equipment has a detrimental effect on the concentrate grade. Reduction of solids entrainment (upgrading) is typically related with a loss in recovery of valuable minerals. For improving the froth transport characteristics and flotation cells design, a better understanding and quantification of the actual solids drainage and entrainment processes are required. In this work, the study of solids transport in the froth of a two-dimensional flotation cell was performed. The prototype cell represents a radial section of an industrial flotation cell (130m3) and was operated at steady state. Experimental tests consisted of adding a small amount of radioactive solid tracer (0.3g) near the top-of-froth or near the bottom of froth (close to the interface). The solid was selected as a non-floatable mineral (gangue) in order to evaluate both the solid entrainment into the concentrate as well as the solid drainage into the collection zone. Solid tracer consisted of fine or coarse gangue particles, P80 of 35 and 120 µm, respectively. Twelve collimated sensors located along the froth and collection zones allowed the evaluation of the solid transport in the froth, and the solid drainage from the froth to the collection zone, after tracer addition at different distances from the discharge lip. Results showed that longer distances to the froth discharge lip, as well as higher particle sizes, promotes higher solid drainage from the froth to the pulp zone, while decreasing the solids entrainment into the concentrate. The same result was observed for the solid located near the top-of-froth as well as near the bottom of froth. This information was complemented by the froth surface velocity measurements, using the Visiofroth system, showing a good agreement between the froth bubbles velocity and the solid transport velocity, measured near the discharge lip.

Jan 1, 2018

By J. J. Liu

In the Bayer process, control of alumina trihydrate particle size, oxalate stability and morphology and foaming is crucial for improving the yield and quality of alumina trihydrate. One way to economically achieve such control is to employ specifically developed chemical additives, termed, crystal growth modifiers (CGM?s). In this paper, the mechanism of action and practical application of CGM?s in the Bayer process are summarized. The application of CGM additives allows for both enhanced agglomeration and secondary nucleation control, and hence coarsening of the particles. Current research efforts have utilized the information gained from mechanistic studies to enhance the performance of CGM products. It was demonstrated in both laboratory tests and industrial operations that the newly developed CGM formulations have a range of properties with enhanced performance, compared to the current commercial products.

Jan 1, 2014

By Sergio Castro, Janusz Laskowski

In the flotation in highly concentrated electrolyte solutions not only ionic strength but also chemical composition, flotation pH and mineral properties play an important role. As a result an improvement or depression may be observed. A strong improvement in the floatability of hydrophobic bituminous coals and other inherently hydrophobic minerals is characteristic for the "salt flotation process", which is carried out in concentrated electrolyte solutions at natural pH and without addition of any flotation reagents. However, pH is a key factor when saline and hipersaline waters with hydrolyzing metallic ions are used as process water. In the case of flotation of Cu-Mo sulfide ores in seawater, molybdenite is strongly depressed by the Mg2+ hydrolysis products when pH is raised to depress pyrite. Process water with a high content of Mg2+ and Ca2+ ions, and this also includes seawater, have deleterious effect on the anionic flotation of industrial minerals with fatty acids. The flotation of potash ores is carried out in NaCl-KCl saturated brine (6-7 mole/L of NaCl and KCl) with the use of long-chain amines. Such a high electrolyte concentration changes dramatically the amine Krafft point making the collector insoluble in brine; its mode of action entirely differs from that in conventional flotation processes.

Jan 1, 2014

By R. V. Kononko, A. Yu. Chikin, R. N. Rakhmeev, Yu. O. Fedorov

"The focus of the study is finding a solution that can help to improve diamond recovery in diamond-bearing gravity concentrates upgrading flowsheets. The purpose of the study was to develop and prove scientifically a separation method of diamonds recovery from gravity concentrates regardless of their fluorescence ability induced by X-ray radiation. Two promising recovery methods applicable to diamonds of this type are proposed, i.e. an X-ray radiometric method based on an instantaneous analysis of a secondary X-ray spectrum of separated particles, and a triboelectric method that relies on noncontact measurements of particle charges obtained during its motion in a vibratory tray. As a part of the laboratory study, X-ray fluorescence spectra of the collection of diamond crystals and main associated minerals and rocks at a particle size of -6+3 mm were produced. The analysis of the produced secondary X-ray spectra showed a significant difference between crystals, minerals and rocks within the analytical area of Ca, Fe and Zr due to the absence of calcium, iron and zircon elements in diamonds. Additionally, the scattered X-radiation level of diamonds substantially increased under the influence of X-ray radiation. Such a difference is a physical base of a new method of diamonds recovery from mineral mixtures. The laboratory study on triboelectric characteristics showed that a significant portion of diamonds gained an electric charge of a magnitude that was much higher, compared to associated minerals and rocks. The laboratory and industrial tests and the separation indicators demonstrated a high efficiency. A proposed X-ray radiometric method provides recovery of all types of diamonds regardless of X-ray fluorescence levels, with high selectivity and recovery rate of at least 98%. This proposed separation method is protected by a patent of Russian Federation (No. 2551486, “A method of X-ray radiometric separation of diamond-bearing materials”). Triboelectric separation organized in two stages (main and control) ensures recovery of up to 98-100% of diamonds at a particle size -5+2 and -2+1 mm,. More than 10 triboelectric separators successfully operate in active diamond processing plants in the Russian Federation."

Jan 1, 2018

By Philippe De Donato, Odile Barres, Mukendi Kongolo, Stoyan Gaydardzhiev, David Bastin, Jean-Marie Kanda

The adsorption patterns of potassium amylxanthate on the surface of high purity malachite subjected to prior sulfidization with NaSH have been followed and elucidated. DRIFTS spectroscopy has been used to trace the associated physicochemical alterations as well as the chemical species present on the mineral surface. Varying the collector concentration from 5.10-4 to 1.10-2 mol/L has led to different degree of surface coverage of the alkyl groups and to formation of organometallic hydrophobic complexes of CuX or CuX - X2 type. The results reveal that the CuX complex formed on the malachite surface without sulfidizing agent is more unstable and prone to dissolution-precipitation phenomena. Based upon the constructed adsorption isotherms and upon the degree of statistical coverage, different zones of mineral-reagent interactions could be distinguished. They correspond respectively to the monolayer, bi-layer and tridimensional condensation domains. In each of the identified zones mono or double layer adsorption patterns of the collector are proposed leading respectively to formation of surface compounds with different degree of hydrophobicity. The results suggest that sulfidisation remains an important prerequisite in view achieving efficient flotation of the malachite from the studied copper ore.

Jan 1, 2014

By B. McFadzean, S. Geldenhuys

"Dynamic froth stability tests have found widespread application to quantify froth performance. However, little to no attention has been given to scale parameters in the performance of these measurements. One of the most frequently changing scale parameters in the laboratory scale is the column diameter as this directly influences the amount of material needed for testing. Four different column diameters (50, 100, 200 and 300 mm) were used for this study. Column diameter experiments were done on an industrial scale by means of manual tracking of froth growth versus time. An increase in measured dynamic stability was seen with increasing froth column diameter, which reached a limiting value at large column sizes. It is thought that this behaviour is controlled by the differences in drainage rates of the bulk froth compared to froth in contact with the wall. The column diameter required to represent full-scale froth stability is proposed. A ratio of column surface area to total bubble surface area was used to correct for different column diameters.INTRODUCTIONThe froth phase in flotation contributes significantly to the overall performance of the process (Zanin, et al., 2009). Numerous parameters have been investigated to quantify froth performance, most notably froth recovery (Feteris, et al., 1987; Seaman, et al., 2004; Vera, et al., 1999). Experimentally gathering data to determine froth recovery is challenging and for this reason froth stability has been highlighted as a possible alternative.Froth/foam stability is defined as the time of persistence of the froth/foam and is affected by numerous factors, such as: drainage of the liquid in the lamellae (gravitational and capillary), viscosity at the bubble surface, thickness of the electrical double layer and gas diffusion through liquid films caused by pressure differences between bubbles (Aktas, et al., 2008; Beneventi, et al., 2001). It is well documented in both froth and foam literature that froth/foam stability will heavily influence the performance and appearance of the froth/foam phase (Ata, 2012; Farrokhpay, 2011; Weaire, et al., 2005). Experimentally this has been explicitly proven as an increase in froth stability, characterised by water recovery, usually results in an increase in both valuable mineral and solids recovery (Wiese, et al., 2011; Banford, et al., 1998)."

Jan 1, 2018

By V. A. Masloboev, A. V. Svetlov, D. V. Makarov

"The methods of heap leaching are considered to be the most promising for the low-grade copper-nickel raw materials. The article presents intensification capabilities of the process. Objects of research: the low-grade copper-nickel ores of Moncheplutone deposits (Moroshkovoye Lake, Nyud Terrasa, Nittis-Kumuzh’ya-Travyanaya (NKT), as well as the copper-nickel ore dressing tailings of the “Kola MMC” JSC. The following directions for the intensification of the low-grade copper-nickel raw materials heap leaching have been considered: preliminary electric pulse destruction (EPD) of ore; ore crushing and further sulfuric acid agglomeration. The impact of sulfuric acid concentration (1-3%) on the extraction of non-ferrous metals kinetics from the copper-nickel ore dressing tailings under various conditions of the percolation leaching has been studied. INTRODUCTION The low-grade grade sulfide ores at the abandoned and producing deposits, overburden rocks, mill tailings and non-ferrous slag are thought to be one of the large-scale sources for non-ferrous metals, on the one hand. On the other hand, they are known to be the subjects of emergency environmental danger. For this reason, the use of mine dumps and tailings, as well as the remained ores left in the ground as raw products, and at the same time decreasing the load on environment, are considered to be the pressing ecological and economic issue (Chanturia et al., 2012). Methods of heap hydrometallurgical and bacterial leaching are sure to be potentially productive for processing such low-grade and technogenic raw materials (Petersen, 2016). The early studies of hydrometallurgical method possibility to process copper-nickel ores of the Murmansk region deposits were launched in the seventies of the previous century (Golovko et al., 1978). For referencing purposes, the main types of impregnated ores from the deposits Zhdanovskoye, Kaula, Sopchinsky Plast and Lovnoozerskoye were selected. The metal content varied, as %: 0.46-1.49 of nickel, 0.01-0.62 of copper. In the first experiments, the solution containing 150g/l of H2SO4 and 135g/l of NaCl, was used in the capacity of leaching reagent. The possibility of underground metals leaching from the ores of the Lovnoozerskoye deposit was justified due to the performed laboratory and further large-sized tests."

Jan 1, 2018

"The thiosulfate leaching process developed by Barrick to treat sulfidic high preg-robbing gold ores uses calcium thiosulfate as the leaching reagent for ores pre-treated by pressure oxidation, resin for gold recovery with sulfite/trithionate elution and reverse osmosis as a means of reagent recovery. A large portion of the research that led to the development of the technology was based on previous studies completed by different groups over the years, mainly focused on the ammonium thiosulfate system. Operational limitations in the use of the ammonia-containing recycled water in the pressure oxidation circuit were some of the main drivers for the change from ammonium to calcium thiosulfate for the development of the industrial scale process. One of the main aspects for successful gold extraction and recovery in the thiosulfate system is the pseudo-equilibrium reactions that drive distribution of the different gold species (in solids, solution and on resin) in the system. Previous studies have been focused on the thiosulfate reactions and equilibrium constants for the oxysulfur ions (thiosulfate, trithionate, tetrathionate). However, the literature around the effects of the different metal-oxysulfur complexes (Cu and Hg complexes) that form when the ore is in contact with the leaching reagents, and the related effects on stability of the gold complex is limited. The main changes in the gold complex chemistry and stability in the calcium thiosulfate system as compared to the ammonium and sodium equivalents, as well as related effects on gold recoveries, were investigated in the presence of different types of double refractory ores. INTRODUCTION Barrick has developed a thiosulfate leaching process to treat double refractory gold ores, by combining the use of acidic and alkaline autoclave pre-treatment with thiosulfate resin-in-leach (RIL). The process currently in operation at the Goldstrike mine (the TCM process), uses calcium thiosulfate as the leaching reagent, resin for gold recovery with sulfite/trithionate elution and reverse osmosis as a mean of reagent recycle. The main feed to the process plant is highly preg-robbing sulfidic ore from Goldstrike’s open pit. Prior to feeding the pressure oxidation circuit, the ore is processed through the crushing and grinding circuits and treated in preparation for acid or alkaline autoclave processing (POX)."

Jan 1, 2018