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By Megan Becker, Cyril O’Connor, Jenny Wiese, Gaynor Yorath

The effect of particle shape on true flotation has been widely reported. The present paper presents results obtained in investigating the effect of particle shape on the entrainment of particles during the flotation process. Different hydrophilic minerals with particles of varying aspect ratios were used and their shape determined using rheological tests and QEMSCAN. Their entrainment properties showed a close relationship to their shape with the recovery due to entrainment increasing as the aspect ratio of the particles increased. The effect of surface charge, by changing pH, and size of particles showed that the effect of shape was sustained at different pHs and particle sizes. Proposals are made to explain these observations in terms of the known relationships between drag coefficients and terminal velocities and shape. Since it has been previously reported that different milling procedures can affect particle shape, these results indicate that it is possible that such different procedures may result in increased entrainment of hydrophilic minerals.

Jan 1, 2014

At times the phosphate industry, in Florida, encounters phosphate rock that gives lower than expected P2O5 recovery in the rougher plant section. The drop in recovery is typically 10% and as much as 30% or more. Variations in feed quality from day to day, shift to shift and even from drag-line to drag line, represent a challenge to the beneficiation plant operators and reagents? suppliers. Therefore, this characterization study has been initiated to identify the reasons for the differences in flotation behavior of such feeds. The study involves many samples to cover such variations. The characterization work includes: ? Mineralogical and chemical analysis; ? Size, shape, surface roughness and porosity analysis; ? Surface charge and surface contamination with other phases (minerals); ? Clay content and its relationship to phosphate and silica particles. The results correlated with flotation data and adsorption density measurements clearly establish the statistically significant variability in characteristic features that influence flotation response. This article discusses results from the above listed studies. On the basis of the obtained data, recommendations of practical approaches to overcome the problem of feed variability in phosphate flotation plants are delineated.

Jan 1, 2014

By Tsuyoshi Hirajima, Hideyuki Okamoto, Himawan .. T. B. M. Petrus, Keiko Sasaki

"Flotation of arseno bearing minerals from their copper ore has been an interest due to the increasing awareness on protecting the environment by minimizing the possibility of exposed arsenic compound. Some approaches have been proposed, but the mechanisms of separations have not yet fully understood. In this study, oxidation using oxygen was applied. Instead of the complex copper ore flotation results, pure single mineral of tennantite and chalcopyrite foatability was conducted using Hallimond tube. Resembled with the flotation results of copper concentrate containing tennantite, the separation possessed the best result at alkaline condition (pH 11) at where the arsenic content was reduced from 3300 ppm to 1800 ppm. In order to be able to understand the mechanism of the separation atomic force microscope (AFM) was utilized. AFM images showed changes in morphology and behavior when minerals were treated in both acid and alkaline condition. It was found that the morphological change showed the reaction products representing the rate of reactivity of tennantite and chalcopyrite. From the measured force of adhesion, it can be observed that in alkaline condition the surface of both minerals is more hydrophilic than that in acidic condition possessing higher value. This is in accordance with the X-ray photoelectron spectroscopy (XPS) spectra in which hydroxide moieties occupied the mineral surface in alkaline condition while elemental sulfur is in acidic condition."

Jan 1, 2014

By F. O. Milovich, V. A. Ignatkina, L. A. Samatova, E. D. Shepeta

"The aim of the research was to increase technological parameters of the flotation of finely disseminated scheelitecarbonate ore using selective reagent regime.In the studies the monomineral fractions of scheelite and calcite; samples of the scheelite-carbonate ore of the Primorsky deposit with the range of the carbonate module 3-65 were used. A carbonate module of ore is the ratio an initial assay of calcite to an initial assay of scheelite. Sodium oleate, iso-decyl alcohol, water glass, calcium chloride, soda or sodium hydroxide as flotation reagents were used. The flotation method in the Hallimond tube and in a mechanical cell, an adsorption method for study the kinetics of adsorption of oleate and isodecyl alcohol and its combinations on scheelite and calcite, IR spectroscopy including ATR to study the composition of surfacecompounds were applied. Selective reagent regime may include two ways - a combination of collectors or a modification of depressants of calcite and other gangue minerals. On one hand the combination of sodium oleate and higher fatty iso-alcohols of fractions C12-C16 in the rough scheelite flotation to reduce the flotation activity of calcite has been studied. On the other hand depression of calcite flotation by calcium chloride with water glass into rough flotation was used; modified the steaming cycle by Petrov's method applying change the concentration of water glass and other. Fatty iso-alcohols can adsorb on the surface of the calcite that reducing the adsorption of sodium oleate and floatability of calcite has been fallen. Their co-adsorbing with oleat on the scheelite surface were support the hydrophobization and flocculation of slime particles of scheelite. Flocculation of the particles of scheelite leads to increased up 3 times of the recovery of scheelite from the slime class, and calcite change up only 1.4-1.1 times it’s recovery.The growth of the carbonate module more than 11 is decreased the assay of WO3 in the scheelite concentrate of selection cycle."

Jan 1, 2018

By Áureo Del Vecchio, Lídia Dely Alves de Sousa, José Pereira

The potassium demand for agriculture purposes has increased in Brazil, which has great deficit of internal demands. Potassium-rich rocks have been used as fertilizers as technological alternatives for agriculture aimed to reduce the amount of chemicals and the sector dependence for such products. Vermiculite tailings from União Brasileira de Mineração - UBM, at Santa Luzia - PB, was studied aiming their application in agriculture by potassium release. The sample was analyzed by XRF and XRD; studies on release kinetic with particles smaller than 2 mm added of organic acids (citric and oxalic) at 10-2 mol/L concentration; samples were analyzed by XRD after kinetic assays. The work was conducted using a shaker incubator at 300-rpm agitation and time variation to better understand the potassium availability in the ground. Results show the presence of K2O at 3.46% concentration. Citric and oxalic acids increased the release speed to almost the same level with speed coefficients (k) of 2.61x10-2 h-1/2 and 2.55x10-2 h-1/2 respectively. In statistical terms for both acids, the linear equation represents more than 99.0% of the experimental assays. Stonemeal was applied to banana seedlings in experiment conducted in a greenhouse. The use of vermiculite tailings in banana seedlings promoted potassium absorption, which influenced its growth. The amount of potassium liberated from vermiculite tailings could be used as a long-term alternative to fertilizers in agriculture cultures.

Jan 1, 2014

By Y. M. Zhu

Lead in environment often causes a serious health hazard. The removal of Pb2+ from aqueous phase is a beneficial project. In this paper, deposited Saccharomyces cerevisiae (S.c.) was chosen as adsorbent, Pb2+ ions as adsorbate, and the process of biosorption was studied. The dynamics of the adsorption was investigated. The adsorption mechanism of Pb2+ by S.c. cells was also investigated by detecting microstructure, zeta potential under different pH value, FT-IR spectra of the S.c. particles before and after biosorption. It was shown that the biosorption of Pb2+ by deposited S. c. is a rapid process, and the adsorbing equilibrium is reached within 10 minutes. The Zero point of zeta potential of S.c. cells is pH=3.3. When 2.0<pH<3.3, there exists biosorption (biosorption rate 76%~88%), which means static bio-sorption been not the only kind of biosorption. FT-IR spectrum analysis showed that groups on bacteria surface were mainly characteristic groups of protein and amylase; oxo-groups and nitric-groups on S.c. cell surface could chelate with heavy metal ions. Chemical adsorption might exist in the process.

Jan 1, 2014

By K. Hori

In this study, the determination of optimal conditions for jig separation has been investigated with a TACUB jig separator. The TACUB jig, from which a Batac jig originated, is a useful gravity separator that is effective to separate crushed solid wastes as well as coarse ores. A mixture of crushed polyethylene (specific gravity 1.3) and polyvinyl chloride (specific gravity 1.5) was separated by a batch TACUB jig by varying the frequency (wavelength) and the amplitude (pulse stroke length). It was found that the sample particle layer in the separation chamber was fluidized without turbulence by the rising water pulse resulting in the separation. However, a too strong water pulse reduced the efficiency of the separation of the particles. The results indicate that the specific velocity of the rising water is necessary to fluidize the particle layer without turbulence to separate the particles. The expansion ratios of the thickness of the particle layer in rising flows were measured in a cylindrical column. The pressure losses by the particle layer were calculated from the expansion ratios and the velocity of the rising flows by Ergun?s equation. The curve of the pressure loss vs. the velocity of rising flow showed a maximum point corresponded to the point of fluidization. The velocity of a rising flow on the point of fluidization provided the optimal separation condition.

Jan 1, 2014

By A. Otsuki

This paper describes the evaluation method of dispersion and coagulation of silica nano-particles by means of interactive force apparatus. The apparatus measures the size of fine particles in aqueous solution or organic solvent of high concentration and/or low optical transparency. Other conventional apparatus for size measurements (such as, apparatus utilizing dynamic light scattering) are difficult to measure the size of particles in such conditions accurately, due to multi-scattering of light in the sample solution or solvent. The apparatus measures the interactive force between two surfaces, i.e. the gold-coated glass hemisphere and the brass flat plate, (which is fixed at the bottom of the sample cell). The apparatus has three parts, i.e. main part (which consists of electric balance, hemisphere and flat plate), control part (i.e. personal computer, piezo-stage controller and voltage supplier), and detecting part (i.e. multi-meter and oscilloscope). During the measurement, electric field is applied between the hemisphere and flat plate, and thus dielectric particles are arranged toward the direction of electric field in the area between two plates. When the two plates are close to each other, two different forces (i.e. repulsive force and attractive force) will alternately act on particles due to the structure change of the particles. The repulsive force occurs when the structure of particles is stretched by compressive force; whereas the attractive force occurs when the aggregate structure is broken. The cycle of the repulsive and attractive forces is a primary size of particle or size of aggregate, which depends on the degree of agglomeration. The measured size of particles, which is varied depending on their degree of dispersion and coagulation, determined the characteristics of the silica particles. In this research work, the effect of size and concentration of particles in aqueous solution on the degree of dispersion and coagulation of the silica particles were investigated. Spherical silica particles were selected for this investigation due to their variety of size. This apparatus can be used to evaluate the degree of dispersion and coagulation of other nano-particles in various solvents in many process industries.

Jan 1, 2014

By M. M. Fan

In Florida?s phosphate industrial practice, the most favorable upper size limit of froth flotation is 1.18 mm which corresponds to particle weight of about 2.8 mg. Conventional froth flotation is not efficient in upgrading coarse particles (+0.425-1.18 mm). A limited number of studies have been devoted to understanding and improving coarse particle flotation. We have shown that the coarse particle flotation performance can be significantly improved by the presence of picobubbles generated by hydrodynamic cavitation. In this study, the size of picobubbles produced under certain hydrodynamic conditions was measured by a laser particle size analyzer. A size-by-size flotation performance analysis of coarse phosphate froth flotation in the presence of picobubbles is conducted in terms of flotation kinetics, selectivity and recovery. It was found that picobubbles doubled the flota-tion rate, increased the P2O5 recovery more significantly for +0.85-1.18 mm particles than +0.425- 0.6 mm and +0.60-0.85 mm particles. At a given acid insolubles (A.I.) rejection, the presence of picobubbles increased the P2O5 recovery by up to about 25%.

Jan 1, 2014

By Masoud Askari, Ahmad Rafizadeh, Shahamat Rostami, Mohammad Qaredaqi

Gole - Gohar Iron ore mines located in Sirjan, Southeast of Iran, have more than 1 billion Iron ore deposit and this area comprises 45 % of Iran Iron reservoirs. The aim of Wet tailing processing line is recovering Hematite ore from wet tailing of Gole - Gohar iron ore processing plant. The Investigations of Hematite recovery plant showed that the recovery of Iron ore to concentrate in Wet Tailing Processing (WTP) line is very lower than that has been predicted, sampling, and designing of the process parameters are not accurate and designed magnetic field intensity is not reasonable for the recovery of Iron in form of Hematite in this line feed. Applying of MIMS in WTP separator and changes in circuit caused in overwhelming increase of Fe recovery, from 11 to 40%. Although recovery of WTP line was improved, but low recovery of this processing line and high content of Hematite ore in WTP tailing, made applying Wet High Intensity Magnetic separators unavoidable. Two kinds of WHIMS have tested for processing of WTP line tailing. Results showed that traditional Jones separator with grooved plate matrix, is more suitable to achieve a better quality of concentrate compared to Slon® separator.

Jan 1, 2014

By S. M. Bradshaw, C. Dorfling, F. Ngandu

"Selenium removal and platinum group metal (PGM) recovery from copper sulfate leach solutions form an integral part of platinum producers’ base metal refinery operations. Recent studies found that substantially higher PGM recoveries can be achieved if excess thiourea instead of sulfurous acid is used as precipitation reagent; however, the impact of the proposed process on downstream processes was unknown. The objective of the current study was therefore to investigate the effects that excess thiourea and residual selenium present in the rich copper sulfate electrolyte have on copper electrowinning. This was achieved by performing cyclic voltammetry tests using a platinum rotating disk as working electrode, a graphite auxiliary electrode and a saturated calomel reference electrode. A synthetic copper sulfate electrolyte containing 0.01 M Cu2+, 1 M H2SO4 and varying amounts of selenium (20 – 150 mg/L) and thiourea (10 mg/L and 100 – 300 % excess) was used. The results obtained have shown that both thiourea and selenium interact with the cupric ion cathodic reduction reaction. Thiourea polarized the working electrode and lowered the efficiency of the cupric reduction reaction. Tests on the solutions with high selenium concentration showed simultaneous reduction of copper and selenium, which led to copper selenide formation. Nodule formation on the deposit surface also became significant at higher selenium concentrations. Based on these results, it was concluded that precipitation of PGMs from the copper sulfate solution with excess thiourea is not feasible due to the detrimental effect on downstream electrowinning operations.INTRODUCTION During the high pressure oxidative leaching stage in a typical base metal refinery (BMR) circuit, selenium, tellurium and some platinum group metals (PGMs) are dissolved along with the desired copper ions. The impurities (selenium and tellurium) may pass to the copper electrowinning circuit where it can result in the formation of nodular copper electrodeposits or reduced current efficiency. The presence of PGMs in solution, on the other hand, increases the precious metal inventory and potential losses of the operation. Currently, sulfurous acid is widely used for selenium and tellurium precipitation from copper sulfate leach solutions. Sulfurous acid is capable of reducing cupric ions to cuprous ions; the generated cuprous ions then react with Se4+ and Se6+ to precipitate selenium as a copper selenide (Bello, Dorfling, 2014). Recent studies have, however, proposed the use of excess thiourea as a precipitating agent for the removal of selenium and tellurium; it has the advantage of improved PGM recovery in the Se/Te precipitation step (Lottering, Eksteen et al., 2012; Mulwanda, Dorfling, 2015)."

Jan 1, 2018

By Ming’an Wei, Chuanyao Sun, Zhenguo Song, Zengwen Dou, Yangge Zhu

"The effects of pH value and dissolved oxygen(DO) in the pulp to the Eh and flotation recovery of pyrite were investigated using potential online detection system. The effects of DO on the Eh and flotation recovery were tested which DO changed from 0.5mg/L to 19.5mg/L in six different pH buffer flotation systems (pH: 4.00, 5.62, 6.86, 9.18, 10.01 and 10.96 respectively). Results of potential detected online demonstrated that the pyrite electrode has nearly the same response to potential as with platinum electrode for the FeS2-xanthate-H2O flotation system under the study conditions. Pulp potential and recovery of pyrite were remarkably influenced by pH, both of them decreased with the increasing of pH and, especially, sharp decreased after pH above 9. As the concentration of DO was increased, the Eh was also increased in all the six different buffer solution, while the flotation recovery was decreased. And the amplitude of variation for Eh was not obvious in acidic and neutral solutions, but on the contrary, the change for flotation recovery was remarkable in neutral and alkaline conditions. This may indicate that the flotation of pyrite will be deteriorated in alkaline and high DO concentration conditions."

Jan 1, 2014

By S. Martins

The aim of this work is to compare three different results of charge motion in a modified 5ft diameter lab mill and to identify differences and similarities in these results. The lab mill is modified from tumbling a ball charge to tumbling a charge of disks. This modification replicates 2D motion. This 2D condition is measured using an instrumented disk (iDisk) and analysed using a video imaging system. The iDisk is equipped with a 3D accelerometer array and rotation rate sensors. With the help of a video system, some measured quantities are also determined externally. The results of these three predictions or measurements are presented. A discussion is included.

Jan 1, 2014

By John Nell, Paul den Hoed

Carbochlorination tests were conducted with matched particle-size fractions of rutile, ilmenite and high-titania slag in a small bubbling fluidized-bed reactor. The effects of temperature, the type and proportion of solid reductant in the charge, and the fraction of Cl2 in the fluidizing gas were investigated. Tests confirm the need for solid carbon in the bed if chlorination is to run at high rates. With solid carbon in the bed, CO supplied with the fluidizing gas does not increase significantly the degree of chlorination after 75 minutes. Ilmenite is chlorinated more quickly than titania slag, which in turn is chlorinated more quickly than rutile. Rates of chlorination at 1100°C and 1000°C are much the same and significantly higher than at 900°C. Chlorination is associated with significant increases in particle porosity (even for rutile), which is brought about by the rapid initial chlorination of FeO and MnO (in ilmenite and slag) and (it is argued) by the chlorination of Ti2O3 which forms at high-energy surface sites. A reaction mechanism is presented; where possible, its validity is demonstrated by the support of empirical observations.

Jan 1, 2003

By Wenying Liu, Marek Pawlik

Long-chain ionic surfactants, with fatty acids and amines as the most important representatives, are widely used as collectors in froth flotation. These surfactants, generally referred to as weak electrolyte collectors, frequently form solid insoluble precipitates within a certain pH range. However, the action and behavior of these colloidal precipitates in froth flotation systems are not well understood and has not been well decoupled from those of dissolved forms. The objective of this study was to understand and compare the role of colloidal precipitates with that of the dissolved forms at gas-liquid and gas-liquid-solid interfaces. Using primary amine as the model surfactant, experiments were carried out to measure: the maximum volume of bubbles generated in the presence of dissolved and precipitated forms of the surfactant; surface tension for both forms of the surfactant using the drop shape and maximum bubble pressure methods; and contact angle using the sessile drop method. The experimental results showed that: in the presence of the precipitate, bubble volume was smaller, which was correlated with the lower surface tension and higher contact angle measured; the surface tension of solutions containing surfactant precipitate was affected by the surface age of liquid droplets. This study enhances understanding of the interfacial behavior of long-chain ionic surfactants under different conditions, which would help improve the efficiency of reagent utilization in froth flotation.

Jan 1, 2014

By Gábor Mucsi, Barnabás Csoke, Viktor Mádai, Zoltán Molnár, Viktor Török, Ádám Rácz

The application of the stirred media mill in dry mode came to the front only in recent years, but at the same time several questions arise, such as aggregation, agglomeration, sticking on the liners and the grinding media. During high energy milling, not only the particle size reduces, but among others, in numerous cases the crystal structure and the amorphous state of the material also change due to the mechanical activation taking place. The present paper deals with experiments carried out on the ultrafine fly ash grinding in dry mode at various grinding conditions in a stirred media mill to investigate the mechanochemical effect and the energy efficiency of the mill. During the experiments the particle size distribution, particle shape, specific surface area, amorphity and crystal structure of the products were examined. The product related stress model was used for the evaluation of the effect of milling parameters on the mechanical activation. It was found, based on the experimental results, that there is mechanochemical effect on crystal structure of fly ash in the stirred media mill, as it was revealed by X-ray diffraction and FTIR measurements. The experimental results made it possible to determine the effect of the rotor circumferential speed and so the stress intensity on the mechanical activation of fly ash could be revealed.

Jan 1, 2014

By V. E. Vigdergauz

The work presented shows results of electrochemical study of pyrite hydrophobicity evaluated by air bubble induction time (IT) measurements. On the basis of measured IT?s an average thickness of the thin liquid film prior to its rupture has been evaluated, which confirms long-range character of the interactions between air bubbles and hydrophobic surfaces. Obtained data are discussed in the frame of recent studies of structures of solid-liquid interface based on molecular dynamics simulations and results of surface force measurements.

Jan 1, 2014

By E. Ashirbaeva

"Ores of ferrous metals traditionally make up the bulk of recoverable reserves of solid minerals, and iron ore concentrates - in the processing and consumption. To obtain concentrates, three main methods are used: dry and wet magnetic separation, gravity and flotation. But even their integration into complex developed schemes with finishing operations often do not solve the problem of obtaining high-quality concentrates, which are necessary for powder metallurgy and electric steelmaking. Increasing the iron content in the concentrate by removing harmful impurities is the goal of this work. The possibility of reducing the operations of wet magnetic separation twice and completely eliminating concentrating operations in ball mills from the scheme of operations has been established. Selective leaching agents for each type of iron ores have been created, allowing to obtain concentrates with an iron content of not less than 68-69% and negligible concentrations of harmful impurities. Methodical recommendations for long-term storage of bioreagents in the active state, their immobilization and preparation in industrial conditions at the enterprise Nedropolzovatelja are developed. The proposed biotechnology, which allows to obtain high quality iron and conditional concentrates for harmful impurities, is protected by patents (RU 2537684 ""Method for fine-tuning of high-sulfur magnetite concentrate"" for magnetite ores and Pat. RU 2599068. For the industrial implementation of the new technology, organizational and technological measures have been developed in the system with Road maps for types of ores. The developed technology makes it possible to condition noble metal, tin, tungsten, nickel and other concentrates in harmful impurities such as arsenic, antimony, mercury, sulfur, copper, zinc, iron, phosphorus, manganese, in total 30 components that pass into solution under the influence of bioreagents.INTRODUCTION Consumption of various metals is steadily increasing every year, the volume of mining is constantly increasing. Ores of ferrous metals traditionally make up the bulk of the recoverable reserves of solid minerals. Enrichment technologies for iron-containing ores are reduced to the combination of three main methods: wet and dry magnetic separation, gravity and flotation. But even the use of complex advanced technological schemes often does not lead to the production of high-quality concentrates suitable for metallurgical processing. In this case, either lapping operations or effective technical and technological solutions are used in the main enrichment cycle. Widely used in practice methods for improving the quality of iron ore concentrates include the use of finishing operations (fine screening, reverse cation flotation), staging of concentrates, the use of more sophisticated equipment (separators with running magnetic field, magnetic gravity classifiers, column flotation machines)."

Jan 1, 2018

By B. Mishra, Rahul Mohanty, Swati Mohanty, Swagatika Dash

Wet high intensity magnetic separators have been widely used in the mineral industry for separation of mineral particles based on magnetic properties. Usually, magnetic separators employ ordered array of grooved plates such as Lenoir and Jones plates onto which the magnetic particles get attached in the presence of a magnetic field. In the present work, we have carried out computational fluid dynamic (CFD) simulation, using Eulerian-Eulerian model to study the flow dynamics of magnetic and nonmagnetic particles within a matrix consisting of 2 mm size spheres of magnetic material, which are interconnected by wires, in the presence of a magnetic field. The three phases considered were the water, magnetic particles and non-magnetic particles. Model equations were developed considering each sphere in the matrix as a magnetic dipole, and the strength of the magnetic field at any point in the domain is due to all the dipoles. The size of the magnetic and nonmagnetic particles was 45 and 40 micron, respectively. The feed consisted of a slurry having 25 wt. % solids. The volume fraction of the magnetic particles was 0.04, and that of the non-magnetic particles was 0.045. The simulation was first carried out without the imposition of the magnetic field till a steady state was reached, and then the magnetic field was applied. The magnetic particles, as they flow down the matrix were attracted towards the region of maximum field gradient, which was in the central region of the matrix. A symmetrical pattern in the upper half as well as the lower half of the matrix was observed. As the particles moved downwards, the pattern changed, and near the outlet, most of the particles were found to flow out from the central part of the plane. This study can lead to a better design of a magnetic separator.

Jan 1, 2014

By Naoki Hiroyoshi, Hajime Miki, Tsuyoshi Hirajima, Masami Tsunekawa

Acidic solutions for chalcopyrite leaching contain cupric, ferrous and ferric ions, and the oxidizing power of the solutions is indicated by a redox potential, determined by the concentration ratio of ferric to ferrous ions. This paper reviews our previous studies on the redox potential dependence of chalcopyrite leaching in sulfuric acid solutions. Leaching and anodic-polarization experiments showed that coexistence of cupric and ferrous ions activate anodic dissolution of chalcopyrite, causing faster copper extraction at the potentials below a certain value (critical potential). The analysis of the AC impedance spectra for chalcopyrite electrode indicated that a high-resistance passive layer grows on the chalcopyrite surface without cupric and/or ferrous ions, and that coexistence of these ions causes a formation of another product layer and inhibits the passive layer growth at low potentials. These results are explained by a reaction model assuming the formation of intermediate Cu2S due to chalcopyrite reduction and the subsequent oxidation of the Cu2S. The critical potential corresponds to the redox potential of the Cu2S formation and the predicted values matched with the experimental results. Catalytic effect of silver ions on chalcopyrite leaching was also discussed based on experimental results and the above model.

Jan 1, 2003