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By L. S. Zhou

HermesTM metal magnetic liner (MML) has been invented and manufactured by China Metallurgy and Mining General Co. (CMMC). This paper describes its mechanism, structure, magnetic field distribution, application, economic benefit and safety performance. The 10 years? service life in Benxi Steel?s Waitoushan Mine, along with 6 years? technological analysis on its application in 5500mm×8800mm (diameter × length) ball mill in Anshan Steel?s Diaojuntai mineral processing plant, has proved its advantages such as super reliability, long service life, light weight, thin thickness, low noise and short payback period. It has also demonstrated its positive effects on the grinding process such as high productivity, energy-effective performance and low consumption of grinding media. It reduces labour intensity and improves working conditions, due to its easy installation, free maintenance and the fact that it doesn?t require fastening bolts or cause slurry leakage. It is de-signed scientifically in accordance with the varieties of processing lines, mill specification, ore type and grinding media, and has been applied in different grinding processes for magnetite, hematite, gold ores, nonferrous ores and other materials. HermesTM MML has three types of products: General, Composite and Heavy-duty. They are designed to meet the requirements from customers in China and abroad. So far, more than 400 sets of MML have been applied in ball mills with diameter rang-ing from 1500mm to 5500mm. It has become highly popular in American market recently due to its safe and effective performance.

Jan 1, 2014

By Chen Dong, Yang Wenwang, Liu Zhineng, Tan Ming

"To meet the requirement of production expanding of a certain potash ore dressing plant in Xinjiang province of China, industrial test of XCF/KYF-50 flotation machine was performed to process potash ore. The tank of XCF/KYF-50 flotation cell is in U shape, 50m3 of volume. This flotation cell is able to suck slurry by itself, and can be arranged on the same base level without high difference. In this paper, two sets of XCF/KYF-50 flotation cells were adopted to replace 8 sets of 8m3 flotation cell in original flow sheet of flotation. Aeration rate, slurry suction capacity, power consumption and slurry suspension are investigated. The measuring results show the slurry suction capacity of the flotation cell is larger than 12.80m3/min and solid particles disperse evenly in the tank without deposition. Industrial test result indicates that the final grade of concentrate is 26.69% at the recovery of 90.95%, which is up to expected performance. XCF/KYF-50 flotation cell has advantages of high flotation efficiency, significant energy saving and reasonable configuration of automatic control system, this kind of flotation cell can meet the requirement of production expanding of this potash ore dressing plant well."

Jan 1, 2014

By B. Csoke

To improve the efficiency of the crushing/screening plant of Bazalt-Középko Kobányák Ltd. (Hungary), the implementation of computer aided quality control is planned. In the current phase, the R & D work aims at the solution of high-priority tasks: 1) Developing the process models, validation of the models by means of industrial measurements. 2) Developing the algorithm for the process control of the crushing/sizing plant. 3) Developing the suitable computer program. To develop the mathematical models of crushing (breakage and probability functions) and to determine the model parameters, the experimental industrial trials were carried out on hydrocone crushers of types Svedala H 4800 EF and H 4800 F, changing the gap size and crushing relatively narrow grain size fractions. Additionally, the parameters of the separation function for the screens operating in the system were determined. It was established that the crushing probability depends on the grain size of the feed (Y) and the gap size (s), so the breakage probability S, for each cone crusher, can be well characterised by the function formed using the ratio of these two parameters: SfYsf==. The distribution of the broken grains can be described reliably using the relative grain size distribution function B(? = x/Y) (usually Schuhmann-Gaudin- or Rosin-Rammler-shaped function). For the screens, the probability function ()2()111/NTx = xd ???---???? is suitable for cha-racterising the separation (where x? grain size, ?-open-area ratio, d ? rectangular screen aperture size, N ? number of appearance of the particle on a screen surface). Using these functions, the comminution circuits were described by means of vector/matrix equations. The calculations and measurements verified the reliability of the developed models and algorithms.

Jan 1, 2014

By Z. He

Based on full investigation of the characteristic of sphalerite in the residue obtained from cyanidation leaching process and the study of the mechanism of the interaction between flotation reagents and sphalerite with the aid of electrochemical analysis, the reagent named YO was developed for eliminating the depression effect of CN- on sphalerite and reducing the dosage of CuSO4. The achievements have been used in commercial production for the treatment of the cyanidation residue to recover the zinc minerals, obtaining a zinc concentrate with grade of 56.49% Zn and recovery of 86.63% Zn.

Jan 1, 2014

By T. Badrujaman

In September 2005, after 30 years experiencing in operating an ESF using a falling water film shell cooling system, Antam entered the new era in operating an ESF, after completely modernized its ESF No. 2 from a falling water film shell cooling system to a copper cooling system. Further, in the beginning of 2007, Ferronickel plant No. 3, where its ESF also uses copper coolers, was successfully commissioned. By operating an ESF using a copper cooling technology, Antam has to face some challenges to establish the operation stability. Besides that, the chances to maximize the furnace efficiency are greatly opened. The shielded-arc mode of electrode tip is selected to operate an ESF under relatively high furnace power to produce metal having tap temperature below 1500? and slag having tap temperature below 1600?. It leads to electric current unbalance. Further, operating an ESF using a copper cooler system under high voltage as consequence of the furnace power raise increases metal and slag tap temperature. This condition damages furnace integrity fast. Besides that, relatively high metal temperature increases its pressure during metal tapping. It leads to failure in closing the metal tap hole. The main different ways in operating an ESF using a falling water film shell cooling system and a copper cooling system lie in the electrode tip mode, the water specification used for cooler, metal tap block maintenance and allowed metal & slag level in furnace. Since a copper cooler system allows an ESF to be operated by consuming nickel ore having ratio Fe / Ni up to eight and producing slag having relatively high Fe content in slag, an undesirable silicon reversion phenomenon becomes an obstacle in reaching the operation stability. A copper cooler technology lets Antam to take a chance to increase its capacity. Modernizing the ESF No.2 had increased its furnace power from 17 MWh to 25 MWh. Meanwhile the ESF No. 3 can be operated up to 42 MWh. This technology allows an ESF to be operated under relatively high furnace power above 25 MWh safely as well as prolong the campaign life of ESF brick. Further, lowering ESF power consumption, extending the limitation of ratio S/M in nickel ore consumed and adjusting Ni grade in ferronickel product can be gained by applying this technology.

Jan 1, 2014

By E. V. Konoplev

Russia is one of the largest manufacturers of potash fertilizers in the world. Processing of potash ores basically is carried out by a flotation way. Potash ores of the Verhnekamsky potash deposit contain sylvite (KCl), halite (NaCl) and water insoluble impurity (up to 8 %), presented silicate- carbonate minerals, easily slimed by ore crushing in rod mills. Ore of some deposit sites, developed by ?Uralkali? Co, contains a significant amount of a carnal-lite (KCl.MgCl2.6H2O). Work practice of flotation potash plants has shown, that increase of car-nallite content in ore leads to increase magnesium ion content in a circulated plant brine (saturated salt solution of potassium and sodium chlorides-sylvite brine) and to deterioration of indicators of ore processing. In the Paper we present results of researches of floatability of various size sylvite and influences silicate-carbonate slimes on sylvite flotation in brines with the various magnesium chloride content. It is established, that with increase magnesium chloride content in the brine mainly decreases the flotation of coarse sylvite and amplifies adverse effect of silicate-carbonate slimes on sylvite flotation. In this connection deterioration of potash ore flotation is caused not only decrease sylvite floatability but also strengthening adverse action of water insoluble impurity on potash flotation. It is shown that the application of frothing agents, which render the stronger dispersive action on the colloidal-micellar structures of amine in the salt solution increases the absorption of collector on the sylvite and improves the flotation of sylvite into magnesium the containing salt solutions. The application of an organic depressor to the greatest degree of decreasing the absorption amine on the slimes and to the smallest degree possessing anionic properties proves to be most effective with the flotation carnallite of the containing potassium ores. It is offered the application the frother on a basis of glycol ethers and organic depressor on a basis of urea-formaldehyde resin. Results of industrial tests developed reagent modes for flotation treatment of ores with the raised carnallite content (to 6 %) on ?Uralkali? Co plant have shown that their application has allowed to receive equivalent indicators potash flotations at change of magnesium chloride content in the brine from 0.7 % up to 2.4 % .

Jan 1, 2014

By Ho-Seok Jeon

The separation in gravity concentrators is based on the density difference between valuable and gangue minerals. In addition to density, many auxiliary parameters like particle size, shape, feed rate, pulp density etc. plays an important role in the separation. The performance efficiency of gravity units is largely based on the interference of such auxiliary parameters during separation. Many gravity concentrators are used for the beneficiation of cassiterite ores and performance of which are varying with different feed material, particle size and required enrichment from the unit. Selection of gravity units is generally based on laboratory testing and data collected from the previous experience. In the present investigation cassiterite ore collected from Uljin deposit, South Korea has been subjected to various gravity units like jig, spiral, and Knelson concentrator with the intension to pre-concentrate the ore. Second stage concentration was carried out using shaking tables. The article mainly summarizes performance evaluation methods employed for gravity concentrators. Selection of gravity circuit for the beneficiation of cassiterite was made on the basis of the recovery-grade curve, and Tromp curve methods. Keywords: cassiterite, gravity concentration, recovery-grade curve, sink-float test, tromp curve

Sep 1, 2012

By T. Bhambhani

Research at Cytec over the past two decades has shown that the traditional approach for ore metallurgical characterization (typically conducted via laboratory-scale batch flotation tests), which involves changing reagents and conditions one-factor-at-a-time, leads to several pitfalls. The chemical solution thus selected has a narrow un-optimized window of performance and will likely fail in the plant. A holistic approach, called the Flotation Matrix 100? process for ore metallurgical characterization, was developed at Cytec about a decade ago and has been successfully used to develop robust reagent solutions for several operations around the world. The premise for the approach is that flotation outcome from ores is variable and is determined by complex interactions between various physical, chemical and operational factors. A key component of the process is the use of efficient multivariate designs focused on the chemistry aspects (reagents and pulp chemistry), which helps identify the best processing conditions for each ore type, as well as the conditions resulting in poor performance. It also includes advanced statistical methods for dealing with the complexity and variability of experimental data. The holistic approach is illustrated in this paper with a case study on Pb/Zn ores. Using just 18 carefully designed batch tests, it is possible to partially simulate the behavior of each ore type in the plant. The best conditions for each ore type, along with the conditions to avoid, are identified. Along with this, insights are obtained into the reasons for high reagent dosages for certain ore types, and interactions between variables. Keywords: flotation, holistic approach, metallurgical characterization, multivariate experimental designs, base and precious metals recovery, sulfide collectors and modifiers, Pb/Zn sequential flotation

Sep 1, 2012

By B. J. Zhang

Conventional spirals are capable of providing excellent clean coal recovery, although at a relatively high ash content. Compound spirals, which provide two stages of spiral cleaning in a single taller unit, have been commercialized in recent years to improve upon the cleaning performance obtained from conventional spirals. The present study aimed at optimizing the performance obtained from a compound spiral for cleaning especially high sulfur fine and ultrafine coal. Industrial-scale spiral units were utilized for this study in a pilot-scale facility at the Illinois Coal Development Park. A statistically designed experimental program was conducted to optimize ash and sulfur cleaning performance of the compound spiral. It was found that significant cleaning of ultrafine coal (i.e., 150 microns × 45 microns and even 45 microns × 25 microns size coal) is achievable with the compound spiral. However, operating conditions for cleaning finer coal fractions (-150 microns size coal) have to be significantly different from those used to clean coarser coal fractions (+150 microns size coal). The sulfur rejection trends were different from ash separation efficiency trends in all size fractions except 45 microns × 25 microns. The probable error (Ep) and effective specific gravity of separation (SG50c) determined for the compound spiral cleaning of the overall particle size were as low as 0.07 and 1.62, respectively. However, the bypass of a small percentage of clean coal to the tailings stream of the compound spiral, may need further adjustment of the key process parameters.

Jan 1, 2014

By I. Baltov

The Chelopech Mine, located in Central Bulgaria, is one of Europe?s largest underground copper- gold mines, currently mines and processes approximately one million tonnes of ore per year. Copper concentrates containing gold and silver with significant arsenic content are produced and sold on the world markets. The operation was acquired by Dundee Precious Metals in 2003. A modernization program for the Mine and Plant has since been in progress to increase both production and mechanical reliability, and also to optimize metallurgical recoveries. Since then, mine output and plant throughput have doubled, plant availabilities and utilization have increased significantly, and overall metallurgical performance for copper and gold improved. The paper presents the systematic approach for obtaining and analyzing data, communicating it, and making suggestions for changes to the technological parameters and flowsheet in order to maximize metal recoveries. These studies have correlated the ore characteristics (particle size distributions, metal assays, and Cu and Au mineralogical and phase analyses) with the actual plant performance (kinetics, recoveries, and throughput). Cu recovery by size has been calculated from the mineralogical analyses of feed, concentrate and tails, with the most significant losses being identified in terms of fraction and phase recoveries. This has provided the recommendations (some of them tested in plant) for changes in the grinding and flotation circuits.

Jan 1, 2014

By M. D. Amirova

Cyanide-free technology of complex copper-lead ores flotation may be improved through enlarged range of pH values, enhanced copper recovery into copper concentrates due to additional recovery of secondary copper sulfides, as well as through enhanced efficiency of lead sulfides depression in process of new flotation modifiers-based selective separation. Study of the effects of flotation modifier (of metal nature) on minerals surface conditions proved that the xanthate is practically not adsorbed on the galenite surfaces due to minerals hydrophilization. Joint effects of sodium sulfite and modifier enhance process conditions for intensive galenite depression and at the same time for effective chalcopyrite and chalcosine flotation within a large pH values range (from pH=8 to pH=10). Identified mechanisms carry inference that proposed chemical reagent treating method is very promising for selective copper-lead concentrates separation. Potential use of carbon-containing materials as zinc flotation modifier to enhancing zinc recovery in processes of lead-zinc ores treatment has been studied. In our flotation tests we used Shalkiya (South Kazakhstan) lead-zinc ores containing such impurities as carbon shales, which presence impedes the process of saleable concentrates production and gives rise to excessive consumption of flotation agents due to the xanthate adsorption on the carbon. Lead and zinc concentrates were produced by process stages as follows: ores milled to 95% Cl. -0.074 +0; lead and zinc roughing flotation and further recleaner and testing operations. Test flotation in open process cycle resulted in enhancing zinc recovery into zinc concentrates by 21.1% and increasing zinc content in zinc concentrates by 3.96% that evidences promising potentialities for use of carbon-containing products as additional zinc flotation modifier. Works were carried out under National Program 2003~2005 of fundamental researches ?Physical and Chemical Mechanisms of Interactions in Multicomponent Solid and Liquid Systems Specific for Integrated Processing of Complex Metal-Containing Minerals and Technogenic Raw Materials? and contractual Agreement 2005 Optimization of Production and Technology of Shalkiya Lead-Zinc Ores Processing at Kentau Dressing Works.

Jan 1, 2014

By Z. Pokrajcic

The traditional comminution circuit is a major consumer of energy ? both as electrical energy and through consumption of media and wear resistant liners. Up to 40% of electrical energy con-sumed at a mine site is attributed to comminution however only a few percent of this energy is used in the generation of new surfaces from size reduction. This paper describes the evaluation of modifications using simulation models based on two operating comminution circuits. The aim of these modifications is to decrease both the amount of electrical energy consumed in the size reduction process, known as direct energy, as well as to decrease the consumption of grinding consumables such as steel grinding media and mill liners, designated as indirect energy. The approach is two-fold: ??Employ, where possible, autogenous grinding techniques to eliminate the need for grinding media and reduce mill liner wear. ??Optimise the use of the grinding energy distribution in the comminution circuit by using more energy efficient grinding devices to target typically problematic features of a comminution circuit such as critical size material from the primary mill and overgrinding in the secondary mill. The investigations show that significant total energy savings, as high as 50% in some cases, can be achieved by employing the techniques described while maintaining circuit throughput and product size. Investigations also show potential benefits in downstream flotation processes as the product size distribution generated from the eco-efficient circuit is generally ?narrower? in shape for improved flotation performance and containing less material in the coarse fraction for overall better liberation.

Jan 1, 2014

By M. Taheri

Multiple Attribute Decision Making (MADM) method is applied to select tailings site of the Gol-e-Gohar Iron Ore Processing Plant in the Kerman province, south-eastern of Iran. To select tailings site, screening is applied on eight location proposed by Binnie and Granges. Consequently three sites identified for further studies. Evaluation factors include only the most important factors such as efficiency ratio, elevation and distance to processing facilities, occurrence of faults and fractures. Crisp values such as efficiency ratio, elevation and distance can be determined by measurements and calculations, but some factors such as occurrence of faults and fractures are presented as linguistic values that can be described with triangular fuzzy numbers. Based on evaluation values obtained an optimal tailings site can be selected using a modified Technique of ranking Preferences by Similarity to the Ideal Solution (TOPSIS) given crisp data and linguistic variables as the alternatives of attributes. Each attribute?s weight is assigned using the analytic hierarchy process. The final ranking order aids in the selection of tailings site. Finally, the stages of modified TOPSIS method were applied and site No.2 situated in 5400m to the mill was selected as the best alternative.

Jan 1, 2014

By M. Bergerman

Sossego was the first Vale SAG mill operation to process copper-gold ore. It is located in Para state, south east of Amazon region in Brazil. The comminution circuit was designed to treat 41 000 metric tons per day comprising primary crushing, one 11.6 m SAG mill operating in closed configuration with cone crushers, followed by two 6.7 ball mills. In the first three years of continuous operation Vale investigated alternatives for obtained improved performance of the circuit by investigating operating conditions, mainly focusing on SAG mill. A number of actions were then implemented, which resulted in significant increase in overall production. Vale then decided to further assess the performance of the comminution circuit as a function of ore characteristics. A comprehensive ore characterization program was then conducted, together with the calibration of mathematical models on the basis of surveys carried out at the industrial circuit. The simulator was then used to predict the production level associated to each ore type, as well as to establish the optimized circuit configuration and tailored operating conditions. The ongoing validation program is planned to consolidate the selected strategy, as well as showing the benefits in adopting such indices in mine planning, as opposed to rather simplistic approaches. This paper describes in detail the main aspects of optimizing the industrial circuit performance, as well as the successful method for predicting the production as a function of ore characteristics.

Jan 1, 2014

Deposit of Jinbaoshan platinum group metals (PGMs) ore ranks the second in Yunnan province, China. Study on process mineralogy shows that the grade of copper and nickel in the ore is just 0.16% and 0.20% respectively. Moreover, the impurities magnesium and iron and silicon are rich in the ore. The copper and nickel sulfides in the ore, especially the minerals of PGMs, are finely disseminated with the gangues like serpentine. Fine grinding is necessary, and high content of MgO in the concentrate is inevitable through traditional flotation technology on the basis of process mineralogy studies. Achievements on process mineralogy studies are applied to guide the flotation tests successfully. Progress on flotation has been made through comprehensive studies. Suitable grinding by two stages is required for the finely disseminated PGM sulphide ore to achieve the liberation of valuable minerals. Stage grinding and stage separation shall be conducted for a better recovery of valuable minerals. The oxidation state of mineral surface of sulphides has a profound effect on flotation of the ultra-fine sulphides, especially the pentlandite. The combined use of collectors enhances the selective collecting on the ultra-fine and low-grade valuable minerals, is of critical importance.

Jan 1, 2014

By B. Tora

The new method of evaluation of grindability of hard coal and its blend is shown. Standard Hardgrove test is used as a base to work out this method. The essence of this method consists of simulation of milling process in close circuit (mill-classifier) and determination of energy consumption and quantity of product under the constant feed flow. The research equipment designed specially for this project is described New method of grindability measuring completes standard Hardgrove method withdrawing its faults: ? bigger (c.a. 10 times) and more representative sample is used; ? the milling process is carried out in close circuit (similarly to the industrial condition); ? energy consumption of the milling process is determined for three samples, which differs in grain size. The new method of evaluation of grindability of hard coal and its blend is shown. Standard Hardgrove test is used as a base to work out this method. This method allows us to determine energy consumption of the milling process. The essence of this method consist of simulation of milling process in close circuit (mill-classifier) and determination of energy consumption and quantity of product under the constant feed flow. Our results will complete the Hardgrove method and will help us to better characterise coal. At the same time investigations in industrial scale are carried out. These investigations will verify this new method. Also a new mathematical model of the milling process is being elaborated. It will be used to predict behaviour of coals in industrial conditions.

Jan 1, 2014

By H. Z. Liu

An extra-refractory gold ore in China belongs to Carlin Type Gold Ore which is not only submicroscopic but also rich in arsenic and organic carbon. They have been proved that its floatability is not good enough and the gold in the ore could not be leached almost if it was not pretreated. The tests for the ore were carried out in accordance with flotation-concentrate preoxidation-cyanidation(or CIL) processes in order to exploit the mine. Two new depressants were discovered in the flotation tests and improved concentrate grades from about 20g/t to 32~50g/t. The methods of the concentrate preoxidation tests were alkaline atmospheric oxidation, acidic atmospheric oxidation, acidic pressure oxidation, roasting oxidation?biooxidation. The cyanidation tests after the concentrate preoxidation have proved the gold extraction of the pressure oxidation to be the highest(92.5%) and that of roasting secondary(89.3%). After fuller techno-economic comparison, it is suggested that the flotation-pressure oxidation or roasting-CIL process should be the most optimal for treating the ore. The gold recoveries of the ore were 83% for the pressure oxidation and 80% for the roasting respectively.

Jan 1, 2014

By B. Peszko

There are many measuring methods of grain sizes. Taking into consideration the fine grained materials, one of the existing techniques is measurement of grain size by the Coulter Counter method. This method is based on the measuring the changes of electrolyte resistance during grains flow through the calibrated diaphragm. This method is relatively simple to apply, significantly precise and the results are given quickly. However, the problem is that the measurements are limited by the size of diaphragm. Because of this situation, measurement of grain sizes by this instrument is possible in range from 10% to 60% of diaphragm diameter. This limitation causes the necessity of re-placing diaphragm in case when the measured grain size distribution concerns the material of large size range. In purpose of determining the total grain size distribution, the synthesis of some partial distributions, given for individual grain fractions (with different diaphragm applied), is required. This is possible to do by calculating the mixture of distribution functions, created from the partial distribution functions. Two materials were selected to research: quartzite and glass, which were comminuted in cylindrical crusher, additionally grinded, screened and then analyzed by Coulter Counter for five grain fractions: 0~125 µm, 0~80 µm, 0~56 µm, 0~40 µm and 0~25 µm. For each fraction, five different partial distributions were given (in case of glass ? four), which are the basis for the creating the joined grain composition. To assure the adequacy of the given distribution function, it is necessary to obtain the possibly best approximation of partial distributions. In the work, both the parametric and non-parametric methods of density approximations of investigated random variable. For each grain fraction the approximations were done by three traditional distribution functions: RRB, GSA and log-norm distribution functions and three methods of non-parametric approximation: Gauss kernel, Epanechnikov kernel and orthogonal Fourier series method. As the criterion of the certain distribution function acceptance, the value of the residual deviation was assumed, given by the formulae:

Jan 1, 2014

By T. Bhambhani, O. Yavuzkan, D. R. Nagaraj

"The recovery of oxide Cu minerals by flotation is a longstanding challenge in the minerals industry, especially for high acid-consuming ores which would not be economical for direct acid leaching. Sulfidization (often using controlled potential sulfidization or CPS) using NaSH (or Na2S) followed by flotation using traditional sulfide collectors is the widely used technique. CPS has certain limitations: a) inability to recover certain oxide Cu minerals because they are refractory to sulfidization, b) high consumption of NaSH (or Na2S), and c) potential health and safety hazards associated with NaSH (and Na2S). Flotation of oxide copper minerals using alkyl hydroxamate (AHX) collector has been studied extensively. Investigations using single minerals and laboratory ore flotation have been conducted in the past to demonstrate the efficacy of alkyl hydroxamates. The technology has been used intermittently in plants. One of the main challenges in plant use has been quantifying the true potential for alkyl hydroxamates for recovery of various oxide Cu species in complex and variable ore systems and identifying the most suitable conditions for optimal use. Quantitative mineralogical analysis using QEMSCAN was used in this study to characterize flotation products lab flotation samples. Analysis of concentrates and tails from hydroxamate flotation and CPS flotation stages demonstrated that certain oxide Cu minerals respond exclusively to alkyl hydroxamates and not to CPS. The hierarchy of interaction of AHX with the various oxide Cu minerals could be inferred from these studies. Finally, these studies also allowed quantification of a group of minerals species, which (erroneously) report as part of the Acid-Soluble Cu [ASCu] but cannot be recovered by flotation, thereby facilitating an estimation of the true recovery potential for alkyl hydroxamate.INTRODUCTIONCopper that is economically recoverable occurs in three major types of ores, which are defined by the modal mineralogy of Cu. For sulfide ores, Cu occurs as sulfide minerals and is satisfactorily recovered by flotation using sulfide collectors. Non-sulfide ores, which contain Cu in the form of oxides, phosphates, carbonates and silicates, described in the industry as “oxide” ores (or ores containing “acid-soluble” Cu or ASCu), are currently treated using hydrometallurgy, which involves leaching with dilute sulfuric acid followed by solvent extraction and electrowinning, unless the ores contain acid consuming gangue minerals such as dolomite. For mixed sulfide-oxide ores (i.e. containing both sulfide and oxide Cu minerals) that do not contain acid consuming gangue minerals, Cu values are easily recovered by flotation of sulfide Cu minerals followed by leaching of oxides (only when a leach plant is available). However, when the ore contains acid consuming gangue minerals flotation is required to recover both sulfide and oxide Cu minerals."

Jan 1, 2018

By M. N. Chandraprabha

Arsenopyrite is often associated with sulphides like pyrite, chalcopyrite and galena in refrac-tory gold ores. Selective flotation of arsenopyrite from associated sulphides is desirable for effective gold extraction when the gold is preferentially associated with the arsenopyrite matrix. By contrast, presence of arsenopyrite in flotation tailings poses a serious environmental threat due to arsenic dissolution. To prevent arsenic contamination from the mine wastes, it would be more economical and environmentally beneficial to remove this mineral during the froth flotation step. Use of Acidithiobacillus thiooxidans in the detoxification of arsenic containing sulphides is outlined in this pa-per. Biomodulation using Acidithiobacillus thiooxidans resulted in the preferential depression of pyrite from arsenopyrite. By suitable conditioning with cells and collector effective separation of arsenopyrite from pyrite was achieved. Biomodulation with wild cells did not yield separation of arsenopyrite from chalcopyrite. However, bacterial affinity could be induced to a desired sulfide mineral through environmentally controlled adaptation techniques. Through the use of arsenic-adapted bacterial cells, selective removal of arsenopyrite from chalcopyrite was readily achieved.

Jan 1, 2014