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By Andrew D. McCallum, Russell A. Heins

"Until the advent of intensive cyanidation, gold gravity concentrates were generally treated by tabling. The table concentrates were smelted while table middlings and tailings were recycled to the milling circuit for further grinding and subsequent leaching in the CIP/CIL circuit. Gold recovery on production tables is relatively low, often only 30 percent, and rarely above 60 percent. Significant factors in tabling performance are; mineralogy and the operator’s experience and ability. Units have been developed by Gekko Systems to treat both batch and continuous gold concentrates. Unit sizes are determined by leach kinetics and the required residence time of the concentrate in the unit.Gekko commenced the commercialisation of intensive leaching of gravity gold concentrates in 1997 with the first commercial prototype of the InLine Leach Reactor (ILR). Over 20 units are now installed worldwide with half that number on the African continent. South African mines, South Deeps (Placer Dome WAJV) and Target (AvGold) have both installed InLine Leach Reactors. Ashanti Goldfields have placed the ILR on their standard equipment list and have six operating units with a seventh on order. AngloGold installed one of the first ILR production units at Morila in Mali.Gekko Systems successfully installed an ILR1000 Batch unit at the Antapite Mine in Peru in December 2002. The unit was installed to treat gravity concentrates and to replace a shaking table. Following installation, gravity gold recovery increased from 15% to 40% of total gold. The unit was operational from start up and the first gravity batch treated achieved 98% gold recovery. The gravity concentrates also have a high silver content and 95% recoveries on silver were also achieved.Preliminary testwork identified that the concentrates required additional oxygen to achieve peak performance. As a result of optimisation work in the laboratory, leach kinetics in the ILR have been excellent with only 6 hours residence required to achieve maximum gold extraction."

Jan 1, 2003

By Alim Gül, Güven Önal

"Recently, there have been some attemps on the treatment of low grade ores and old plant tailings due to the decrease in high grade ores and the increase in the metal consumption with increasing world population. Cost of mining and beneficiation of low grade ores become prohibitive since the costs of grinding before flotation make the process unfeasable. Therefore, preconcentration of these ores prior to flotation becomes more important. The concentration of ores preconcentrated in coarse sizes provides a decrease in investment costs as well as grinding and flotation costs. Additionally, the requirements of less space for tailing disposal and less reagent consumption are also important from the viewpoint of environmental considerations.In this study, ore sample containing 0.6 % Cu and taken from Küre-Asiköy ore body was used. Ores contained chalcopyrite and pyrite as main minerals and diabaz, quartz, chlorite and sericite as gang minerals.Samples were all crushed under 9 mm by considering the preliminary studies and float and sink experiments were carried out with the sample in the size range of –9+1 mm using different densities of heavy liquids. As a result of these tests, it was shown that 60 % of the material should be discarded as tailings with 0.1 % Cu content. By considering float and sink test results, the following experiments were performed by using heavy medium cyclone and jigs.As a result of heavy medium cyclone tests, which are conducted on the sample in size range of –9+1 mm, 57 % of the feed material was discarded as tailing with 0.08 % Cu content and 7 % Cu loss, while a concentrate containing 1.43 % Cu was produced with 93 % efficiency (Table 1). Jig tests were done with the samples in the size range. As a result of jig tests with –9+1 mm size group sample, approximately 46 % of feed material was discarded as tailings with 0.13 % Cu content and 10.6 % Cu loss, while a concentrate with 0.94 % Cu content was obtained (Table 2)."

Jan 1, 2003

By Dilip Kumar Mohanty

In today?s world, Sustainability is the key issue before the mankind. With the ever-increasing population & unimaginable boost in industrial growth to cope up with a steady increase in demand and fast change in life style of a human being, the natural resources are exploited to such an extent that the very existence of living beings in this earth planet is threatened. In such devastating situation, the concept of Sustainability emerges out as a great savior. This concept focuses on minimum/ judicious use of natural resources, thereby preserving the resources for future generation while meeting the bare minimum requirement of the present generation. For an emerging economy like India, Mining and Mineral based industries form the back bone of our economic development. Thus, sustainability of mining and mineral processing industry has a far reaching impact on sustainable economic development of our nation. While at a macro-economic level, we have to strike a balance between economic development vis-à-vis socio-economic & environmental impacts, Industries have to ensure judicious and frugal use of natural resources by making use of energy efficient plants & machineries and adopting befitting technology for reduction & recycling of waste. In the context of the above, it would be interesting to look into the sustainability measures taken up by National Aluminium company (Nalco) at its Crushing & conveying plant at Panchpatmali Bauxite Mine, which is incidentally Asia?s largest Bauxite Mine. In the backdrop of the above stated facts, in this paper the authors make an attempt to bring out the sustainability issues in areas of energy conservation, environmental impact/pollution vis-a-vis mitigation measures adopted in crusher & conveyor plant of Panchpatmali Bauxite Mine & CSR / peripheral developmental activities undertaken by Nalco to mitigate the socio- economic impacts. Keywords: sustainability, energy efficiency, recycle, csr, peripheral development

Sep 1, 2012

By Sudhir Srivastava

India hosts a wide range of globally significant mineral resources, including four fuel minerals; 11 metallic minerals; 22 minor minerals and 52 non-metallic minerals. The country ranks among world?s top five nations for its commodity reserves of coal and iron ore. Interestingly, only small part of country's landmass has been explored that provides opportunity for future substantial mineral discoveries. India plans to double infrastructure investments to US$ 1trillion. Despite the challenges in infrastructure project implementation, mining sector remains a key driver of demand growth for commodities in the years to come with a good prospect to grow in future.

Sep 1, 2012

By Pamela Castillo, Marcia Muñoz, Rodrigo Luca, Brian Townley, Fernando López

In the present study we discuss the value of multi-element geochemistry as a tool for semi-quantitative to quantitative bulk mineral characterization in geological and geo-metallurgical modeling of porphyry copper type deposits, with an emphasis on hydrothermal alteration associations, types and intensities. In mine production of porphyry copper deposits much effort is placed on ore grade and geological modeling, applied for predictive mineral processing behavior, from blasting, grinding, leaching or flotation, down to waste disposal and environmental management. High confidence geological models are commonly based on geological mapping of drill core and surface/ underground exposures, combined with discrete mineral characterization (e.g., petrography, QEMSCAN®, spectroscopy, etc.). Unfortunately these are expensive and applied to limited numbers of samples, thus lacking sufficient representation and not suitable for geo-statistical modeling. In addition, geological mapping always presents uncertainty, based mostly on qualitative estimates. The combination of information usually provides geological models that are hard to combine with geo-metallurgical data, much less with mineral processing predictive behavior models. The advent of multi-element geochemistry, at low cost, has allowed employment of such tools massively, yet little use is given to the data, usually focused on elements of economic interest (main ore and credits) and elements of negative impact to concentrates and/or process. Geochemistry reflects the mineral composition of rocks, thus allowing characterization of lithology, alteration types and intensities, and mineralization. As examples of such applications we present generic classification techniques which were developed on various porphyry copper deposits of northern Chile, these based on multi-element geochemistry, allowing for semi-quantitative to quantitative high resolution modeling of key aspects of lithology, hydrothermal alteration and mineralization, and which may be cross-referenced to metallurgical test samples and by that, to geo-metallurgical properties of rocks and modeling. In addition, as data is quantitative and continuous, modelling of gangue can benefit from geo-statistical modeling.

Jan 1, 2018

By Jan Cilliers

The demand for minerals has never been higher. Moreover, the rate at which this demand is growing is unprecedented, and expansions and new mines will be required to fulfill these growing needs. This, in turn requires a skilled engineering workforce that can develop and operate minerals extraction processes to utilise effectively more complex ores. The International Mineral Processing Council (IMPC) has established a Commission on Mineral Processing Education to consider the global challenge of ensuring an adequate supply of well-trained mineral processing engineers. The Commission has, for the past four years, been collecting international information of the recent mineral process engineering supply position and with a view into the near future. The data collected by the international Commission members are as follows: ? Undergraduate student numbers in minerals engineering ? A breakdown of their male/female ratio ? The fraction of the students from each course that enter the minerals industry ? Teaching staff numbers and age profile This data has been collated and analysed, and the findings are presented. It is clear from the analysis that the supply situation is very different in different regions of the world, and that great opportunities exist for targeted recruitment into the industry to meet the future talent demand. Further, an attempt at correlate the supply of minerals engineers based on the local mineral production rate is shown, which shows that there are clear outliers.

Sep 1, 2012

By Jacek Kolacz

A new sensor based sorting system has been developed, based on complex image analysis, where an image texture and a shape pattern is considered for identifying particles for separation. The sorting system employs different images generated by visual light and X-ray to provide maximal information about processed particles. Application of X-ray makes it possible to analyse the internal structure of the particles, which provides a 2D image with complicated texture, however, which contains valuable information. The advanced system for the texture and the pattern recognition is applied to analyse these images simultaneously, to provide the required identification of the particles for efficient separation. The mathematical models applied during identification and separation, are assisted by high speed calculations being specially optimised for this kind of process. This allows sorting with high capacity and high accuracy, which is critical for practical applications in mineral processing. The paper describes a number of tests during sorting of iron ore and coal with high separation efficiency.

Jan 1, 2014

By Kilian Neubert, Hermann Wotruba, Henning Knapp

Sensor-based sorting has been integrated into more and more applications in mineral processing over the past decades. Various sensor types, such as line scan cameras, near infrared sensors and X-ray transmission sensors, allow the separation of a vast variety of raw materials. Sensor-based sorting has several economic benefits which can make the difference between an uneconomic operation and a profitable mine. Sensor-based sorters can be applied to fulfill various sorting tasks, such as waste rejection, product quality improvement and ore type diversion, and have a significant impact on the layout of the processing plant. Therefore, it is important to include sensor-based sorting into the planning of a processing plant at an early stage. To evaluate the applicability of sensor-based sorting for any specific ore type, it is currently necessary to provide several hundred kilograms of material for subsequent bulk tests. In exploration, ore samples are usually rare and only available in form of drill cores. The acquisition of drill cores is time-consuming and expensive especially for deposits in great depth. Hence, it is unfavorable to spoil valuable drill cores for bulk tests. This paper describes a methodology to evaluate the applicability of sensor-based sorting based on drill core analysis. That methodology offers the possibility to calculate the achievable performances of different sensor types for various grain sizes without comminution of drill cores. The general methodology is shown on basis of an exemplary test work on drill cores from a currently conducted exploration.

Jan 1, 2014

By Shen Zhengchang

Based on the flotation features of coarse particle mineral, a new type of impeller & stator unit is developed. Particles suspension state generated by this impeller & stator unit under different speeds are tested in laboratory, and critical impeller speed suit for coarse particles flotation is presented. Comparing particle suspension parameters of the new impeller & stator unit with that of KYF impeller and stator unit, it comes up that the distance between the interface of two slurry circulation channels and the cell bottom is larger in the flotation cell with new impeller & stator unit. The test results indicate that the new type of impeller & stator unit is suitable for processing coarse particles due to its good suspension capacity for coarse particles. Keywords: coarse particles, flotation, suspension, critical speed, impeller and stator unit

Sep 1, 2012

By James A. Finch, Linda Restrepo, Mitra Mirnezami, Amy Buchanan, Maryam Hashemi

Settling rate studies on slurries from Cu/Zn flotation plants occasionally reveals two aggregation maxima at pH 8-10 and 10-12 (Figure 1). From measurements on sphalerite and silica suspensions the double maxima could be replicated. These maxima correspond to the effects of Zn and Mg ions. The aggregation mechanism of both ions is related to the formation of the corresponding hydroxide precipitate. A combination of chemical and electrostatic bridging by the hydroxides is considered to be the aggregation mechanism.

Jan 1, 2003

By M. H. Moys, H. Dong

"Discrete Element Method (DEM) has become a standard tool to simulate grinding mills in order to gain information about load behaviour, power drawn, etc. However, parameters necessary to run a simulation are not always readily available. For example, the coefficient of restitution used in DEM simulation from the literature ranges from 0.1 to 0.9 due to lack of accurate values. The lack of correct input parameters results in the fact that some simulation parameters are adjusted to match the simulation prediction with the experimental results. It is inappropriate to tune one single parameter arbitrarily in order to fit the prediction with experimental results. The correct value of parameters for DEM simulation should be established, and rigorous validation on simulation results by DEM needs to be done.The objectives of the ongoing project are to measure the coefficient of restitution at conditions analogous to grinding practice. Equipment has been built to measure the coefficient of restitution. A typical case of impact test showing the vertical position of a ball as a function of time is presented in Figure 1. The coefficient of restitution between steel ball of different sizes and the targets including steel liner (e = 0.91), mild steel block (e = 0.57) and rubber liner (e = 0.7) have been measured. The coefficient of restitution reduces to 0.38-0.52 when there is a layer of coal particles (1-2 mm) on the steel liner. The effects of ball size, drop height on coefficient of restitution are investigated. Then a DEM code is developed of several contact models to simulate the impact process. This code can reveal details on velocities (translational and rotational) and forces (normal and tangential) during the brief impact interval. Figure 2 is a comparison of the rebound rotational velocity between experiment and prediction by different models. The results can be used as DEM input and to assess contact models."

Jan 1, 2003

By Tatyana A. Ivanova, Tamara N. Matveyeva, Anatoliy A. Fedorov, Tatyana V. Nedosekina, Valentin A. Chanturiya

"As native gold resources are depleted, gold-sulfide ores consisting essentially of pyrite, arsenopyrite, chalcopyrite and pyrrhotite become one of the major precious metal sources, being presently estimated to account for more than 40 % of total world gold reserves.The prime objective of flotation of gold-bearing sulfide minerals is to increase precious metal recovery and to reduce the product cost through achieving maximum selectivity of the separation process. Separation of Fe and As sulfides in selective flotation of gold-bearing ore products helps reduce the amount of ore mass being sent to hydrometallurgical processing, and permits of recovering gold from As-free gold-containing pyrite concentrate by using a lower-cost pyrometallurgical procedure.An ingenious methodology purposively developed by the authors for comprehensive assessment of flotation properties, electrophysical characteristics and crystal chemistry features of natural gold-bearing sulfide minerals of different origin has been used in this study.Comparison of the elemental composition, non-stoichiometry and flotation activity of different monomineralic pyrite varieties revealed that samples with negligible impurity content are nearly stoichiometric, and show similar flotation properties. Samples with high Cu, As and Au contents are highly non-stoichiometric and readily floatable, even in a highly alkaline environment. Samples with high surface sulfur content and the most defective crystal lattices, with iron atoms substituting for sulfide vacancies, are most sensitive to depressive action of the alkali.A correlation between the type of conductivity, impurity content and amount of xanthate compounds on the surface and in the liquid phase of monomineralic pyrite and arsenopyrite suspensions detected by the extractive spectrophotometric analysis has been identified and analyzed. Experiments showed that the proportion of cuprous xanthate in sorptive collector layers on sample surfaces increases with increasing Cu content of the samples. In general, pH for pH, overall xanthate sorption on pyrite is greater than on arsenopyrite, with the difference increasing in passing from an acid environment to an alkaline one. A significant decrease in xanthate sorption on arsenopyrite is observed at pH greater than 9, whereas sorption on pyrite markedly decreases at pH greater than 11."

Jan 1, 2003

By L. Tavares

The significant capital and operating expenditure of size reduction operations have maintained comminution on the spotlight of mineral processing research during the last century and, more recently, the concerns about the impact of these operations on the sustainability of the minerals industry, will remain to do so in the 21st century. One of the most popular approaches that have been used to deal with these challenges is the application of simulation both to reduce the uncertainty in the design and improve the operation of size reduction operations. From the initially purely empirical approaches, including the energy size reduction ?laws? and the phenomenological approaches, of which the traditional population balance model is, arguably, the best example, comminution modeling now reached a point in which more fundamental and mechanistic models are sought. The paper analyzes some of the advances that now make multiscale modeling of comminution processes realizable. On the microscale, greater understanding of the phenomena involved in fracture and fragmentation of single particles under different stressing conditions now exists. Particle breakage testing methods are currently used in a routine basis by industry and good quantitative descriptions of different breakage mechanisms are now available, although research is still required to develop appropriate models for a couple of them. On the macroscale phenomena, the discrete element method (DEM) has been successfully used not only to provide insights but also quantitative information on the transfer of mechanical energy from the machine to the grinding media in mills and to particles in crushers, while smoothed particle hydrodynamics (SPH) and computational fluid dynamics (CFD) to describe fluid flow. The paper also analyzes the importance of modeling mesoscale phenomena in size reduction, which is the interaction of particles forming assemblies or beds of particles, demonstrating some of the areas requiring further attention. Examples of application of the multiscale modeling approach to the inadvertent comminution of ore lumps during handling, to the comminution in vertical impact crushers and tumbling mills are demonstrated. Keywords: comminution modeling, DEM, SPH, CFD, multiscale modeling approach

Sep 1, 2012

By N. Panteleeva, E. Konoplev, I. Michailova, S. Titkov, T. Gurkova, T. Chumakova, Sylvinit Co.

"INTRODUCTIONFlotation of mineral particles by cationic surfactants – namely alkyl amines and their derivatives – is finding ever growing application in processing of various ores and in quality refinement of the benefication end products, iron concentrates for example. In the recent years application of cationic collectors - alkylmorpholines - enabled the development of new highly efficient procedure of water-soluble mineral processing, being also the one with low energy consumption. This procedure is a reverse flotation of carnallite from bay salts of salt-pans and from carnallite ores.The efficiency of cationic SAS influence depends upon colloid-chemical state of the collector in flotation liquid phase, especially if the latter comprises mineral salts. Availability of clayey impurities or slime particles of iron oxide in cation flotation feed, which actively sorb the cationic collector, deteriorate considerably the cation flotation performances. In Halurgy Institute the investigations of cation flotation under potash and carnallite ore processing have been carried out, and new reagent modes, enhancing cationic surfactants sorption at mineral particles, have been developed. Application of new reagents enables one to decrease considerably the consumption of expensive cationic collectors and to enhance the floatability of coarse mineral particles."

Jan 1, 2003

By Renato S. Costa, Afonso H. Martins, Flávia D. Mendes

"This paper presents some important aspects regarding the ion exchange treatment of an Ni and Co sulphate acidic liquor using chelating resins. Chelating resins possessing iminodiacetic or bis-picolylamine functional groups were compared in terms of nickel and cobalt recovery. The experimental resin with bispicolylamine functionalities (Dowex M4195) was evaluated with respect to Ni and Co uptake, and compared with Rohm &Haas commercial chelating iminodiacetate acid resin.The use of selective ion exchange to recover metals from sulphuric acid liquors has been studied for a long time. Companhia Vale do Rio Doce (CVRD) has been actively involved in hydrometallurgical applications of IX and has researched in selecting the optimum resin for nickel and cobalt selective removal and the design of a suitable IX circuit. When an IX operation is contemplated for a specific application, it is followed a screening process which generally involves consideration of the solution composition and pH, speciation of the metals in the liquor to be treated and other possible techniques that can be applied to achieve the desired specifications or recoveries. Once a decision has been made to use IX for a specific application, relevant testwork should be done to select the most cost-effective resin and design the IX circuit to achieve the desired criteria. The experimental part dealt with the working conditions, resin characteristics and the influence upon the resin maximum exchange capacity of the following factors: nickel concentration, temperature, pH and resin-to-solution ratio. Based on the experimental data obtained, it has been proposed a innovative technological treatment"

Jan 1, 2003

By R. Van Hille, S. Lacour, A. E. Lewis, K. Peterson

"This paper compares thermodynamic modelling results with those obtained for copper sulphide removal from aqueous solution in both continuous and batch experiments at laboratory scale. Sulphide precipitation has been demonstrated to be an effective method for heavy metal removal. The advantages are the high degree of metal removal at low pH, low quantities of sludge formation, the ease of de-watering and low reactor retention time due to high reactivity of sulphides. However, the low solubility of sulphide species can lead to spontaneous nucleation of fines, which are difficult to remove.Theoretical modelling was carried out using ASPEN Plus™ and OLI systems Inc ESP process. Both simulators were used to calculate copper sulphide recovery and residual aqueous copper concentrations as a function of pH. The predictions were then compared with experimental results. Both simulations predicted that all of the inlet copper would precipitate as sulphide CuS(s) over the entire range of pH and sulphide: copper molar ratios investigated. The simulation results were strongly influenced by the number of chemical species and the nature of the thermodynamic data taken into account in the model.The continuous experimental studies were carried out in a fluidised bed reactor (FBR). Copper sulphate was reacted with sodium sulphide and the solid precipitated directly onto the pellets in the FBR. The use of sulphide was motivated by high sulphate levels in local acid mine drainage and the ultimate integration of the metal removal process with a biological sulphate reducing process that produces an aqueous sulphide stream.A maximum dissolved copper removal of 99.6% (AAS analysis) and a total removal efficiency of 95.8% (dissolved copper minus fines) were achieved. Stoichiometry of the precipitate was determined from SEM/EDAX analysis (atomic percentages) and was close to 1/1, irrespective of the operating conditions."

Jan 1, 2003

By P. A. Harvey

Previous studies have reported that inorganic electrolytes can enhance floatability of coal. The research has shown that the enhancement, if any, is highly dependent on changes in solution pH, type of electrolyte, and electrolyte concentration. The reasons for this are still not clear. In this study the floatability of coal particles in mono and divalent salt solutions was investigated. The zeta potential and hydrophobicity of the coal was measured experimentally, and a modified Hallimond tube was used to determine the floatability of coal particles by single bubbles, where the collision efficiency was equal to unity. The experimental information was used in conjunction with the Hogg-Healy-Fuerstenau equation to quantify the electrical double layer interaction. It was found that for low electrolyte concentration (less than 0.1 M) solutions the flotation recovery of coal particles was less than that for distilled water, and decreased with increase in concentration. Conversely, at electrolyte concentrations above 0.1 M, flotation recovery increased with increasing concentration (Figure 1). Both of these results are consistent with previous observations, but are inconsistent with expectations when considering the possible influence of electrical double layer interaction. Modelling of the system indicates that the electrical double layer is compressed with increasing electrolyte concentration, resulting in an increase in flotation recovery due to a diminishing of the (electrical double layer) repulsion between the bubble and the coal particles. Moreover, for electrolyte concentrations above about 0.1 M the electrical double layer is completely depressed and would have little further influence, if any, on the flotation process. Therefore, the electrical double layer interaction is not the principal determining factor for the flotation of coal in electrolyte solutions.

Jan 1, 2003

By S. M. Marr

"Water availability and water-related environmental impacts are now one of the most significant challenges facing primary production within the global minerals industry. Whereas the industry has, to a large degree, been able to demonstrate a collective response to greenhouse gas emissions and global energy demand, no such strategy exists for water. In part, this is because water quality and availability are regional issues, but also too because water quality cannot be defined by a single attribute, and extrapolation of any set of water quality indices to their associated environmental impact is no trivial matter. In design situations specifically, the situation is exacerbated by the fact that process engineers typically focus on site water management, and consent authorities are primarily in catchment level issues. As a result, an integrated approach to water management is difficult. This does not stem from an unwillingness by members of the professional team to engage with the total picture of water quality and availability, but principally from the fact that there is no common language through which to approach the problem.It is imperative for process engineers to extend their design system boundary, to reflect the geographic scales over which water impacts need to be quantified. It is not suggested that chemical engineers and metallurgists should become experts in geochemistry, hydrology and limnology. Rather, the challenge is to develop tools through which better communication of the relevant environmental impacts can be achieved.It has been estimated that 50% of the capital for new plants is devoted to handling wastes. The integration of mass exchange processes, adopting a life cycle analysis framework for considering environmental impacts and shifting the emphasis from effluent concentration to environmental impacts should be adopted in the framing of the design problem have been suggested as techniques of Environmentally Conscious Design. Shifting the focus from effluent concentrations and legislative requirements to evaluating the environmental impact is an important step towards improving the overall environmental performance of a process facility."

Jan 1, 2003

By Grigori I. Voiloshnikov

"The long-term studies on development of the technology for precious metals recovery using activated carbons executed by Irkutsk Research Institute of Precious and Rare Metals and Diamonds (IRGIREDMET) were finished by successful introduction of ""Carbon-In-Pulp"" process in Russia (1984).The review of some studies, accompanied by development, testing, introduction and subsequent improvement of considered technology, carried out by IRGIREDMET is submitted in this paper.The basic regularities of gold and silver adsorption onto activated carbons from cyanide, thiourea, chloride and other solutions are investigated using various phisical-and-chemical methods ( X-ray photoelectron spectroscopy, Voltammetry, X-ray microanalysis etc.). Using voltammetry it was found that gold cyanide is adsorbed onto activated carbon without chemical changes and partial reduction of gold is possible only during drying of carbon samples before analysis. Metallic gold and silver may be dissolved in boiling cyanide solution at argon atmosphere when they are in contact with activated carbon surface. Gold adsorption mechanism for activated carbons has great differences from that for the ion exchange resins. So the most probable mechanism for gold adsorption from cyanide solution is adsorption of neutral molecules Me n+[Au(CN)2-]n.X-ray quantitative microanalysis technique was developed to investigate gold adsorption kinetics onto spherical activated carbon. Gold profiles in granules of activated carbon for various adsorption conditions were tested (carbon particle size, mixing efficiency, adsorption time etc.). Mathematical methods were used to determine gold diffusion coefficient within activated carbon granule.The properties of various types domestic and foreign activated carbons were tested and the demands to activated carbons suitable for gold extraction were determined. As a result foreign and Russian activated carbons AG-90, AG-95 were recommended for use at Russian gold plants. Domestic adsorbents are cheaper in comparison with foreign activated carbons. The methods to restore carbon adsorption activity including acid treatment and thermal reactivation were tested and implemented."

Jan 1, 2003

By O. A. Punishko, G. G. Mineev, Zabaikalsky Ore-Dressing Plant, M. V. Malova, O. V. Belousova, S. A. Bogidaev

"In order to intensify benefication processes (flotation and magnetic separation) for rebellious tantalitecolumbite ores electrochemical machining of pulp (ECM) is suggested instead of costly mechanic-chemical activation and magnetizing roasting. Any change in the surface mineral-semiconductor potential under the action of electrochemical treatment results in the change in the isoelectrical state of the surface and the adsorption property of the mineral with respect to ionogenic reagents-collectors. In this case conditions are created for regulating the ion composition, reduction-oxidation potential and pH of the liquid phase of the pulp without any extra introduction of expensive and often ecologically harmful chemical substances.Ores containing tantalum and niobium are characterized by complex chemical composition, determining their physical properties (conductivity, dielectric penetration, magnetization value, etc.) and their electric susceptibility.The authors investigations show that the pulp electrochemical treatment leads to the increasing magnetic susceptibility of the paramagnetic minerals. The main chemical elements forming the columbite-tantalite minerals except tantalum and niobium are iron and manganese. They determine the rare-metal minerals paramagnets properties. The electrochemical treatment changes the relation of the oxidized and reduced forms of these elements having. The method of cathode pulp treatment before flotation is successfully tested industrially.In the field of noble metals metallurgy new technological proposals are reduced to the following. As is know, the production of noble metals from unusual raw materials demands the elaboration of principally new technologies new technologies in so far as the methods for gold and silver extraction from ores are as a rule low elective and at the existing level of engineering are economically not expedient.The analysis of the main trends in the field of non-standard raw material treatment shows that the perspective ones are the geo- and biotechnological processes (underground leaching and leaching in heaps - UL and HL and microbiological methods of metal extraction)."

Jan 1, 2003