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By H. Lieberwirth, M. Hesse

"Selective comminution (SC) is beneficial for the treatment of primary raw materials, especially if it is utilized in the pre-concentration process. Pre-concentration processes are applied in mineral processing to relieve subsequent processes and to achieve a higher efficiency. SC is also a promising method for the treatment of low-grade ores and waste dumps. With SC, various components can be separated such as valuable minerals from waste, ore from wall rock and different ore varieties within a deposit. SC is a property of a comminution system and leads either to a preferred crack propagation in one component (called preferential breakage) or to a preferred crack propagation along the grain boundaries (called interfacial breakage). SC results from different comminution behavior of various components in the feed material. For mechanical comminution, the preferential breakage seems to be the most important case of SC. Hereby SC generates only the difference in the particle size which can finally be used as a sorting parameter. A sorting process which uses SC depends on three parts: the feed material, the comminution machine and the separation machine. The feed material defines the potential for SC. Differences in properties like strength, toughness and density which are related to comminution are often used. The comminution machine has to exploit this potential. The extent of the exploitation can be influenced by the machine design, material and operational parameters. After SC, the various components are still combined in the product. So ultimately, a separation machine is needed. At preferential breakage, a simple screening machine can be used. The basics about SC will be presented at first. This contains relationships between material properties, the kind of loading in the comminution machine and the SC effect. These basics can be used for example to exploit a potential to SC for a pre-concentration step or to avoid the SC for a higher efficiency of subsequent processes. Based on recent investigations with impact load, the influence of the important parameters compressive strength, density, particle size and impact velocity to the SC will be shown, using examples of lead-zinc ore comminution and fluorspar processing."

Jan 1, 2018

By S. Mitra1

"This study aims to investigate coarse particle detachment mechanisms (particle diameter > 150 ?m) utilising both experimental and numerical technique. Two mechanisms were studied – (i) interactions of bubbleparticle (BP) aggregate with vortices and (ii) coalescence of bubble-particle aggregates. On the first mechanism, interaction behaviour of coherent vortex structures with a BP aggregate (bubble diameter db = 3 mm, particle diameter dp = 0.3 mm) was studied using a CFD model in the Reynolds number range of 100 to 1000. Effect of surface hydrophobicity on the BP stability was examined using a range of contact angle boundary conditions. To address the second mechanism, interactions of bubble-particle aggregate (db ~ 4 mm, dp ~ 0.4 mm) with both free gas-liquid interface and individual bubbles were investigated using high speed imaging. Both rebound and coalescence outcomes were observed to be responsible for BP instability leading to particle detachment.INTRODUCTIONIt is widely known that flotation process performs excellent mineral recovery for base metal ore particles that are typically in the range of ~ 20 to 150 µm in diameter (Jameson, 2010). More specifically, higher recoveries are usually reported for particles in the size range of ~20 to 70 µm while outside this spectrum, generally the recovery diminishes significantly. It would be highly desirable to improve the recovery of particles at the coarse end of the flotation size range spectrum which has significant economic benefit (Jameson, 2010). However, it is essential that insights to particle detachment phenomenon, the primary impediment in coarse particle flotation caused by the underlying hydrodynamic factors are first obtained at a greater depth.In an ideal quiescent liquid medium, due to inertia, coarse particles deviate substantially from the fluid streamlines and collision efficiency with bubbles decreases which can only be augmented by increasing turbulence level in the medium sufficiently to make random physical contacts with bubbles. Nonetheless, even if successful contacts are made, it is difficult for these large particles to remain attached to bubbles in a turbulent shear flow environment. There are two major mechanisms postulated for particle detachment – interaction of turbulent flow structures (eddies) with BP aggregate and coalescence among surrounding aggregates. Earlier work of Schulze (1982) theorised a vortex acceleration component to characterise turbulence effect on BP aggregate instability in flotation machines. Wang et al. (2015) investigated bubble detachment behaviour from a stationary particle in a nearly homogeneous and isotropic flow field. Using PIV (particle image velocimetry), it was shown that the local maximum energy dissipation rate for the case of bubble detachment was significantly higher than the no detachment case, and was also higher than the critical value for bubble detachment calculated using Schulze’ theory (Schulze, 1982). Later, Wang et al. (2017) also visualised the BP aggregate instability in a cavity flow leading to particle detachment which was attributed to bubble coalescence, bubble surface oscillation and particle deceleration phenomena."

Jan 1, 2018

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 Carlos Pereira, Fábio de São José, Francielle Nogueira

Votorantim Metals Corporation is one of the leader companies in the extraction of zinc in Brazil. One of its mines, located in the city of Vazante - MG, was composed by zinc silicate ores, but recent studies have indicated a change in mineralization type with arise of zinc sulphide’s ore bodies with disseminations of galena (PbS) and silver. The liberation size between sphalerite and galena in this ore occurs in very fine granulometry (approximately 18µm), fact that has negatively influenced into the flotation process. Aiming to reduce this problem, studies about the use of dispersing in the flotation process have started. Thus, this study investigated the action of different reagents dispersing on the stability of the suspensions. The tests were carried out with samples of mineral galena and sphalerite using four types of dispersing within two different dosages and two pH. The reagents tested were sodium hexametaphosphate, sodium silicate, carboxymethiylcellulose, and sodium polyacrylate. The results of the dispersion tests were analysed in relation to dispersion index. The tests with hexametaphosphate showed high dispersion for both galena and sphalerite. The sodium polyacrylate and arboxymethiylcellulose showed a high dispersion index for galena and a low index for sphalerite implying that reagent can be used in the concentration process of galena.

Jan 1, 2014

Calcium sulfate whiskers are considered to be a prosperous reinforced material in application due to their high mechanical properties. But the hydration occurs easily at moist atmosphere or in aqueous solution. The surface topographies of the calcium sulfate hemihydrate whiskers and the hydrates were analyzed by on-line observation and using XRD. The results indicated the transformation of the crystal type and shape of calcium sulfate hemihydrate whiskers and the reduction of whiskers? aspect ratio. The hydration process of the calcium sulfate hemihydrate whiskers and the effective parameters were further discussed based on FT-IR measurements. The conclusions were obtained that the hydration of calcium sulfate hemihydrate whiskers can be divided into the three phases, namely, initial hemihydration phase, dehydration phase, and coarsening, dissolving and the re-formation of calcium sulfate dehydrate crystal phase. In addition, it was found that in the hydration process of calcium sulfate hemihydrate whiskers the calcium sulfate dihydrate whiskers are formed at first and then converted into the calcium sulfate dihydrate with different crystal shapes, but in the hydration of gypsum hemihydrate the gypsum dihydrate is formed without transition products. The surface active site-calcium ion which has strong trend to react with H2O, the surface ?OH and the inner channels are considered to play important roles in the hydration process of calcium sulfate hemihydrate whiskers.

Jan 1, 2014

By Michael. H. Moys, Clayton Bhondayi

An electro-resistive measuring technique developed by the authors was used to study the effects of superficial gas velocity and froth height on froth phase bubble sizes as a function of height above the pulp-froth interface. Flotation tests and the bubble size measurement were carried out in a laboratory mechanical flotation cell that was operated in a pseudo-steady state mode using primary rougher tailings slurry from Lonmin Platinum as feed. The values of intra-bubble impact distances (IIDs) which are the estimates for froth phase bubble sizes obtained from the measurements indicated that as superficial gas velocity was increased, the values of IIDs decreased for the two froth depths tested. Increasing froth height at fixed gas rate resulted in an increase in IID values especially close to the froth surface. Changing froth height and gas rate alters froth residence times; longer froth residence times mean more time for bubbles to coalesce hence larger values of IIDs and vice-versa.

Jan 1, 2014

By C. Y. Sun

Flotation of chalcopyrite and unactivated malachite with xanthates (ethylxanthate, butylxanthate, octylxanthate and dodecylxanthate) is studied in this paper. Minerals interacted with xanthates are detected by FTIR, and simulated by molecular mechanics. It shows that chalcopyrite can be floated with 4 kinds of xanthates, and unactivated malachite can?t be floated with ethylxanthate but can be floated directly with later 3 kinds of xanthates while characteristic absorption peaks of those four kinds of xanthates are all detected by FTIR on chalcopyrite and malachite surface. After simulating the interaction between xanthate and mineral, it shows that H2O and OH-can interact with chalcopyrite and malachite, and their interaction energy may be so called energy bulwark which must be overcome by collector when collector interacts on minerals; the two sulfur atoms in xanthate group interact with copper and neighbor iron atoms on chalcopyrite. It also shows that molecular mechanics results with logP of collectors can interpret the mechanism of xanthate-mineral on atom scale.

Jan 1, 2014

By Gabriel C. Aguilera, Juan Arismendy

"The effect of rheological factors inside of a hydrocyclone is very relevant for the fluid mechanics and for the classification of materials on suspension, since parameters such viscosity and thixotropy are intrinsic variables that depend of the particulate system and the continuous phase; they determine the efficiency of classification. Nevertheless, the exact knowledge of the main characteristics and magnitudes of them inside the hydrocyclone is very difficult because of the geometry of the hydrocyclone, even more if the hydrocyclone is of small diameter. Hence is not possible to make a hydrodynamic study with effects over classification regarding these variables. This work studies the rheological variables inside a small diameter hydrocyclone that works at high pressures, using the information given by a model of Computational Fluid Dynamics (CFD). The model used includes the Reynolds Stress Model (RSM) for the evaluation of turbulence, and the Volume of Fluid (VOF) to study the interaction between water and air, which is very important to obtain regarding the effect of the air core over the performance of the equipment. The validation of the CFD model was done with a kaolin suspension at several conditions of solids contents below the critical volume fraction, without chemical additive aid. These conditions are representative of current work parameters on plant. As result it could be established the ranges of evaluation of rheological variables on specific regions inside the hydrocyclone, and through a rheometric study, based on the mechanic characteristics previously obtained, the main rheological characteristics of the mineral suspensions were determined."

Jan 1, 2014

By J. Shibata

The behavior in electric field of fine particles present in aqueous solution was measured in order to apply to the classification of fine particles. The sample particles used are spherical polystyrene particles with the average diameter of 0.03 µm, 0.1 µm, 1.0 µm, 4.3 µm and 9.6 µm. Electrophoretic mobility and zeta potential of various particles are measured by an instrument based on the principle of the laser Doppler effect. The influence of temperature, electrolyte concentration on the electro-phoretic mobility was investigated for various polystyrene particles. The electrophoretic mobility increases with increasing pH and temperature of suspensions. The measured electrophoretic mobilities are different from electrolyte concentration and particle size. The electrophoretic retardation effect and relaxation effect are considered to explain the behavior of fine particles in electric field by applying the electro kinetic theory of Wiersema et al. For all particle size, the electrophoretic mobility decreases rapidly in high concentration of KNO3 such as 0.1 mol/dm3due to the compression of electric double layer The forces acting the particles in electric field are considered to be electrical force, friction force and some other forces like relaxation effect and electrophoretic retardation effect which appear in ionic behavior. It is considered that the particle moving velocity depends on the particle size. When the particle size is less than 1µm, the velocity increases with increasing the particle size. On the oth-er hand, the velocity deceases with increasing in particle size, when the particle size is larger than 1µm. This phenomenon is considered to be interesting from the viewpoint of classification for fine particles. We found that the electrophoretic mobility of 1.0µm particles is larger than that of 0.1µm particles, and that it is possible to classify fine particles by using the difference of electrophoretic mobility by many experimental results. The phenomena can be explained by the forces acting the fine particles in the electric field. We can apply the behavior to classification of fine particles.

Jan 1, 2014

Opportunities to monitor and control primary grinding mill performance are strongly sought after in the mineral processing industry. Currently, limited on-line information about mill charge motion and content is available to mill operations for control purposes, leading to periods of lower throughput, instability, variable product size and accelerated mill liner and lifter wear. In response to this need, CSIRO has developed an on-line surface vibration monitor for primary grinding mills which produces data that has been shown to provide new information about the mill charge in terms of toe and shoulder position, as well as potentially key features such as the overall charge level, the distribution between rock and balls in the mill, and the impact of the charge on the mill liners and lifters. This paper outlines the key features of the on-line monitor system, particularly those relating to data transmission, data analysis, and the design of the monitor and its independent power supply. It describes the coupling of single vibration sensor data from the CSIRO on-line monitor to the actual operating conditions of a SAG mill and how the vibration response and hence mill operating conditions vary as a function of time, including during mill equipment failures such as a broken discharge grate. Opportunities for improved mill control based on the data from the on-line monitor are also discussed, as well as the implications in terms of mill processing and maintenance performance. Recently a CSIRO monitor was also installed on a ROM ball mill and analysis of the vibration sensor data from this installation is currently underway. Preliminary findings from this installation will be presented along with comparisons of generic information, such as toe position (measurement precision and operation variability) and vibration signal (intensity, sensitivity and operation variability), between this type of primary grinding mill and AG/SAG mills.

Sep 1, 2012

By M. Gonzalez Fernandez

"Commercially introduced in 2004, the SAGDesign™ test has today proved its efficiency for sizing SAG mills for a wide variety of ores, from very soft to very hard ones. The interest of building a model using the SAGDesign™ test specific energy is the introduction of such a model into a complete process simulator making it possible to predict a complete material balance. The developed model compares the required specific energy with the energy provided by the mill. This energy calculation is derived from the Austin Power Formula. The specific energy provided by the test is corrected, using various parameters, such as the Ball Mill Work Index, to take into account the true operating conditions, the feed and product sizes. The core of this model allows the determination of the product d80 using the mill geometry, its operating conditions and of course the SAGDesign™ test results. To be included in a simulator, the model must also predict the overall size distribution of the SAG mill discharge. Assumptions to answer this point are presented here. The model has been implemented in the USIM PAC simulator. It is used either to predict the product size distribution for a given SAG mill, but also to size a SAG mill for getting a required reduction ratio. INTRODUCTION Over the last few years several types of new comminution machines have been introduced in the market. The most notable newcomer was the HPGR (Morley, 2006). But, even when these machines have some advantages, they have not earned the trust of the mining industry. That is why the established technologies still being the first choice. And, in comminution, that first choice are SAG and ball mills. The design of ball mills has been well understood for a long time. The Bond Ball Mill Work Index is the standard test which helps to describe the ore in terms of energy requirements for milling. Unfortunately, the development of an equivalent test to characterize the ore subject to SAG milling has taken some time. As of today, several tests are available in the market, like the MacPherson test, the MinnovEX SAG Power Index (SPI™), the JK Drop Weight Test, the SMC Test® and the SAGDesign™ test (Verret et al., 2011). The SAGDesign™ test, developed by John Starkey in Canada in the early 2000s (Starkey et al., 2008, 2015), has become one of the standards to assess the grindability of an ore in a SAG mill. One of its advantages is the reduced sample mass needed to perform it, hence, the reduced cost. The second one is that the output of the test is straightforward, it is the energy required to grind the ore between two sizes. Because of this energetic approach, the results provided by the test can be directly applied to size a new mill or to assess the performance of an existing mill."

Jan 1, 2018

By R. Prakash

Column flotation has now gained wide application in the recovery of various minerals. The performance of the flotation device depends on the mixing characteristics of the phases inside the devices. In this work, quality of mixing in a flotation column has been analyzed by using information entropy theory. Empirical models have been developed for flotation column with the parameters which affect the quality of mixing. The efficiency of the particle separation in the flotation column has been enunciated based on the quality of mixing. The present analysis on the quality of mixing in flotation column may give insight into a further understanding and modeling of flotation devices in industrial applications.

Sep 1, 2012

By Michael Young, Rodrigo Araya, Cesar Gomez, Le Huynh, James Finch

The performance of flotation machines is closely related to the gas dispersion characteristics achieved in their operation. It is known that frothers play a major role not only in the size distribution of the generated bubble population, but also on the swarm rise velocity. A program to characterize frother effects on two-phase hydrodynamics (air-water) of Jameson cells was undertaken in a fully instrumented pilot unit installed at McGill University. Gas dispersion parameters (gas velocity, gas holdup and bubble size distributions) of the gas-liquid mixture generated in the downcomer were measured after its release into the separation chamber. The unit was operated under different conditions including gas velocity, liquid jet velocity and frother concentration (MIBC). Bubble size distributions for concentrations above the critical coalescence concentration (CCC) were narrow with Sauter mean diameter between 0.6 to 1.3 mm. The bubble size followed the general trend as encountered in other types of flotation machines, i.e., rapid decrease with increasing frother concentrations below 10 µL/L, and almost no change in size for concentrations above 30 µL/L. The CCC was between 10 and 15 µL/L. Strong correlations were found between bubble size and air-to-liquid flow ratio (APR), and between the bulk density of the aerated solution in the separation tank and the vacuum inside the downcomer. An equation is proposed to estimate gas holdup in the separation tank from vacuum and bulk density readings.

Jan 1, 2014

By D. Pienaar, B. McFadzean, T. Jordaan

"Dithiophosphate (DTP) collectors have the lowest affinity for sulfide mineral surfaces compared to other common sulfide mineral collectors, such as xanthates and dithiocarbamates. In some cases it has been found that DTP does not adsorb onto the mineral surface at all and yet increases in recoveries and grades are noticed with the addition of DTP. Many studies have investigated the interactive effects of collector mixtures. However, there have been relatively few studies on the interactive effects between frother molecules and collectors. This study investigates the interactions between different types of frothers and sodium diethyl dithiophosphate.The study found that there were large increases in pyrite and galena microflotation recoveries at both pH4 and pH9 when DTP was mixed with small amounts of frother at a constant bubble size, showing that these increases were neither mineral-specific nor pH-specific. The same effect was not present when xanthate was used as a collector. The increases in recovery when using the DTP-frother mixture were similar irrespective of the type of alcohol or polypropylene glycol frother that was used. In an attempt to distinguish the mechanism of enhanced flotation recovery, various supplementary experiments were performed. It was found through adsorption experiments that no DTP was adsorbing on to the mineral surface. Therefore, interactions at the air-water interface were performed. Surface tension and critical coalescence concentration tests showed that, while DTP is a weak surfactant at the air-water interface, it does not have a synergistic effect in the presence of frother. DTP-frother mixtures do, however, show interactions in the froth phase, indicating an interaction in the thin films. It is proposed that there is a DTP-frother interaction on the bubble surface that enhances the rate of film thinning at the 3-phase bubble-particle contact."

Jan 1, 2018

By F. Bello, R. Yanez, M. Pinto, T. Errazuriz

"Throughout its operation, Minera Esperanza (ME) will deposit one of the largest tonnages rates of high density tailings in the world with a solids concentration of close to 67% by weight. The tailings presently being deposited have a solids concentration of approximately 62% - 64%, and so cannot be used to directly characterize the flow and deposition characteristics of the higher concentration tailings. To increase the knowledge of the behaviour of their tailings, ME, with the support of Golder Associates, developed a large scale tailings deposition test with a capacity of 30,000 tonnes per day (1,200 m3/h). The test was carried out by depositing tailings into two large cells or paddocks in five stages. Multiple spigots were used to allow different flows to be deposited. At each stage, topographical surveys of the natural terrain and the geometry of the deposited tailings, as well as continuous flow measurement and periodical rheological characterization of the discharged tailings were conducted to create a data set against which beach slope models could be calibrated and then used to predict performance of the higher concentration tailings under different deposition scenarios. This study adopted the beach slope prediction model proposed by A.L. Li (Li, 2011). The model was successfully adjusted to the observations made during this large scale field test by applying the values measured in-situ. This paper presents the application of the model, the results obtained, the findings, and the analysis of possible future scenarios. The model was applied, using the discharge flow rate, the geometrical characteristics of the discharge area, and the rheology with its variation along the beach to estimate the development of the beach formation and the steady state of the beach slopes. Through the use of dimensionless variables, the model was applied to higher solids concentration scenarios, obtaining results that would allow beach slope estimation at different deposition stages in multiple scenarios of varying parameters such as flow, rheology and geometry of discharge area."

Jan 1, 2014

By Rodolfo Silva, Antonio Peres, Afonso Martins, Gilberto Ramalho, Mario Cabello

The consumption of aggregates in civil construction has increased considerably in Brazil for the last years. The extraction of sand and gravel generates significant environmental impacts. As the quarries and sand deposits are getting exhausted near the big cities, the price of aggregates is increasing. Meanwhile, the extraction of quartzite (dimensional stone) in the state of Minas Gerais has been done mostly in small quarries, with very low recovery, generating approximately six million tons of wastes a year, which causes pollution, increases final prices of products, decreases the life time of quarries and ends up in the closure of enterprises. The government agencies and the quarries’ owners understand that only by finding applications to wastes there will be development to the sector. The aim of this investigation was to study the application to the quartzite wastes as aggregate in the civil construction. Samples of quartzite wastes collected in a quarry were characterized by petrographic analyses. Laboratory tests of crushing and grinding were done to analyze the viability of reducing the size of coarse material to a finer one to be used as raw material in industrialized mortars and concrete pre-molded components.

Jan 1, 2014

In this study, the effect of different regrinding conditions on the depression of fine pyrite at the cleaner stage was investigated. The regrinding condition was manipulated by different grinding media (stainless steel and mild steel). It was found that, after regrinding with mild steel grinding media, the flotation recovery of pyrite is much lower than with stainless steel grinding media, and it is more difficult to restore by adding more collector. This means, regrinding with mild steel grinding media may depress the pyrite flotation more strongly. The copper activation of pyrite during regrinding was also studied. It was found, that the mild steel grinding media is more beneficial to copper activation than stainless steel media. Additionally, the analysis of pyrite recovery based on the particle size indicated, that the fine particles are more susceptible to different grinding environments than intermediate and coarse particles and therefore are more easily depressed with a much lower flotation recovery.

Sep 1, 2012

By Lina Chica, Arturo Barrientos, O. Bustamante

Hydrocyclone is a device commonly used in mineral processing industry. Underflow control plays a fundamental role in hydrocyclone operation. This affirmation supports the fact that hydrocyclone underflow has effect in some aspects of separation performance like capacity, split ratio, cut size and bypass. Hydrocyclone operation state is associated to underflow characteristics: air core formation and discharge shape. Many studies attempt to understand size separation phenomenon and the discharge influence but none of them has taken an energy point of view. This work presents the results of a mechanical energy dissipation for hydrocyclone operation from a mechanical energy balance. The experimental results related to Newtonian suspensions show that underflow energy dissipation does not control the operation because this magnitude is small compared to interior energy dissipation. However, discharge energy dissipation provides enough information to describe underflow conditions and its influence in separation conditions. In the modelling non dimensional parameters have been considered for hydrodynamic description and for geometrical and operation hydrocyclone characteristics. Energy dissipation from the continua media approximation results into a relevant concept to understand the hydrocyclone performance and improve industrial installations.

Jan 1, 2014

By J. R. Cui

The production of electric and electronic equipment (EEE) is one of the fastest growing areas. This development has resulted in an increase of waste electric and electronic equipment (WEEE). In view of the environmental problems involved in the management of WEEE, many counties and organizations have drafted national legislation to improve the reuse, recycling and other forms of recovery of such wastes so as to reduce disposal. Recycling of WEEE is an important subject not only from the point of waste treatment but also from the recovery of valuable materials. Consumer electronic equipment (brown goods), such as television sets (TV), radio sets, and video recorders, are most common. However, recent work on recycling of waste electric and electronic equipment (WEEE) primarily focused on personal computer and printed circuit boards scraps. Based on a detailed characterization study of consumer electronic scraps, recycling of TV scraps oriented to recovery of metals is highlighted by utilizing air table separation, eddy current separation, and optical (metal) sorting process. The result indicates that a high recovery of copper could be obtained by utilizing an effective gravity separation process. The separation results reveal that air table separation is an effective technology to recover metals from consumer electronic scraps. By using a DGS table, approximately 90% of non-ferrous metals were recovered in the heavy product with a purity of 40%. Printed circuit boards and cables in TV scrap cause metals loss due to the fact that metals in printed circuit boards and cables are not liberated from plastics and ceramic materials. The study shows that eddy current separation and optical (metal) sorting process provide alternatives for recovery of metals from shredded TV scraps.

Jan 1, 2014

By Arkady Senchenko

The paper deals with the problem of refractory gold-containing material processing. It is observed that all traditional methods for liberation of fine gold from this type of products are characterized by a number of essential disadvantages, where the main ones are ? considerable expenses for ore processing and big environmental impact. As an alternative to the existing methods there is considered a gold liberation method, which is based on the combination of ultra fine grinding process with the consequent atmospheric oxidation. The theoretical justification of atmospheric oxidation was carried out, in the result of this the mechanism and the degree of sulphide minerals? oxidation was found out, the dependence of gold dissolution speed on the slurry content in liquid phase produced by grinding and oxidation was identified. The experimental data and results of pilot-plant testing are given and the most effective grinding and atmospheric oxidation mode is selected on this basis. The performed complex of research works allowed us to use the provided technology at the gold processing plant having capacity of 8 mln. tons of ore per year. The questions, problems, advantages and disadvantages of atmospheric oxidation technology for refractory gold-containing concentrates are considered in this paper. Keywords: refractory gold-containing material processing, gold liberation method, cyanidation

Sep 1, 2012