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By A. Y. Senchenko, Y. V. Kulikov

"The most common technique for selection of grinding equipment is the Bond method implying determination of a ball mill work index (BWi). The method is perfect for greenfield projects where a ball mill must be sized to grind an ore to 80% passing 75-100 µm. Finer grinding will require application of specific correction factors to a standard equation since initially the method was not designated for sizing of fine (minus 75 µm) grinding mills. Significant issues are related to selection of grinding equipment for treatment of originally fine materials when the standard procedure is not applicable. In 1984, Levin published his special technique titled as “A proposed test for the determination of the grindability of fine materials”, where he offered to use the standard Bond ball mill for determination of a specific grinding energy. However, this method did not meet with wide recognition. In 2017, Institute TOMS under guidance of JKMRC’s specialists performed a testwork aimed at verification of a new universal technique for determination of grindability of initially fine materials. An object was to test three aged tailings samples for the subsequent modelling of comminution circuit and evaluation of potential throughput of the existing ball mills with final grind size of ?80 passing 53 µm. In parallel with development of the universal approach, TOMS’ specialists carried out tests according to the Levin method in order to compare the data resulted from two methods. The results from lab ball mill testing on three products following the alternative test methods are presented in this paper along with the testing methodology and results analysis. Specific energy was calculated for regrinding of the materials to the required size. Difference of the examined methods and assessment of their applicability for sizing of full-scale equipment are explored."

Jan 1, 2018

By M. M. Bugarin, P. J. van Staden, V. T. Conic, S. S. Dragulovic, R. M. Kovacevic, D. B. Milanovic

"The mineralogical and physico-chemical characteristics of a polymetallic sample from a mine of West Serbia suggest that it can be classified as a SEDEX type of ore. Those ores contain multiple value components, being inter-dispersed as fine grained aggregates. This prevents concentration by gravity or flotation concentration processes. Mineralogically, the valuable metals (Cu;Zn;Pb;Au and Ag) occur as pyrite, sphalerite, galena, tetrahedrite, chalcopyrite, covellite, arsenopyrite, and non-metallic minerals (barite, and waste minerals). Novel technologies are under development within this project for the recovery of all valuable metals from this very complex material. The work comprises the further treatment of solid residue obtained after Cu and Zn extraction by bioleaching, for the subsequent recovery of Pb and the precious metals Ag and Au. The residue is first treated with a saturated sodium chloride solution, whereupon a chloride solution of lead (NaPbCl3) is obtained. From the chloride solution, lead was deposited in the form of lead carbonate, followed by reductive melting, whereupon lead anode was obtained. Electrolytic refining of the lead anode, using a solution of PbCO3 in methane sulphonic acid (MSA-Methanesulfonic acid, min 99.5% CH4O3S, density 1.48 kg/dm3, Manufacturer: Carl Roth) as an electrolyte, yielded refined lead cathode. It should be noted that, after precipitation and separation of lead carbonate, the sodium chloride solution is restored to its original composition by the addition of make-up reagents and returned for another lead-sulfate leaching cycle. The solid residue obtained after leaching lead-sulphate, is leached in thiosulphate solution, with the addition of an activator, a catalyst and lixiviant for gold, to yield a thiosulphate solution of gold and silver. Since the content of gold and silver in solution is low (below 1 mg/dm3), they are first electrolytically concentrated on steel cathode and then refined to pure metals using well-known chemical methods. Note that, after the electrolytic separation of gold and silver, thiosulphate solution is recycled to the leaching step."

Jan 1, 2018

By Z. M. Dai

Microorganisms in AMD (Acid Mine Drainage) were enriched in 9K culture medium. The enrichment was applied to leach copper pyrite after the microbial community structure and metabolism was stable. Before and after bioleaching, the microbial DNA was extracted and applied to RFLP (restricted fragment length polymorphism) analysis to demonstrate the relationship between the leaching efficiency and the change of microbial community. Atomic absorption spectrometry results showed that when concentration of the pulp was 10% and pH were 1.5, 2.0 and 2.5, the leaching rate were 56%, 57% and 34% on the 18th day respectively. These results indicated that the rise of pH resulted in the decrease of leaching rate. In lower pH condition, the growth of microbe was faster: when pH was 1.5, the microbial cell number reached to 1.4×107cells/mL on the 9th day; while pH was 2.5, the microbial cell number decreased to 4×106cells/mL. The analysis of microbial community structure showed that Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans were dominant species before bioleaching (account for 43% and 32% respectively). And after bioleaching, these two species were still dominant when the initial bioleaching pH were1.5 and 2.0. While the initial bioleaching pH was 2.5, the proportion of these two species decreased. These results demonstrated that the initial bioleaching pH would affect the microbial community structure in bioleaching system at room temperature, and this affect could lead to different copper pyrites bioleaching efficiency.

Jan 1, 2014

By S. S. Yu

In this paper, the producing process of using V2O3 as raw material to obtain vanadium nitride was analyzed through the means of thermodynamic. The analysis shows that conversion follows the principle of reduction step by step in the conversion process of V2O3. The temperature of the reaction system has prominent influence on the nitrogen content of products, and the reaction is very sensitive to temperature. As raising temperature, the fine grain structure of the nitrides is more evident, and the grain size of nitrides increases. At 1703K, the nitrogen content of the products tended to be constant after soaking over 3 hours.

Jan 1, 2014

By Y. H. Tang, H. Y. Zhang

"Tailings from lead-zinc mine contain plenty of dolomite and low-grade fine-grained barite, which is difficult to enrich by mineral processing. Since the density of barite and dolomite has some differences due to the fine dissemination size in a complex sedimentary, the gravity separation tests were conducted with no results obtained. The magnetic separation was conducted to remove the magnetic gangues, and the results were not satisfactory because of the gangue minerals such as limonite and others were low in content. The results of floatation tests showed that the mineral separation of barite and dolomite is quite difficult because that they have similar mineral floatability. Experimental research shows that the good results can be obtained by “desulfurizationbarite floatation” processing with the new depressant TS. The barite concentrate containing BaSO4 91.27%, BaSO4recovery is 70.25% when sodium dodecyl sulfonate serves as a collector and TS as the depressant.INTRODUCTIONBarite is an important mineral material. Often associated with other minerals, it usually needs to be separated by mineral processing in order to meet the application requirements. The main barite beneficiation methods include hand sorting, gravity separation, floatation, magnetic separation, acid leaching, etc. Usually barite associated with oxide ore such as fluorite dolomite, quartz ore etc. are also associated with sulfide ore such as pyrite, sphalerite and galena. The separation between barite and sulfide ore (such as pyrite) is easy. On the other hand, the separation between barite and oxide ore (such as dolomite and fluorite) is very difficult. There are quite a lot of reports on the separation between barite with fluorite dolomite however the separation between barite and dolomite is seldom discussed.The ore properties are quite complex attributable to mineral assemblage containing a large amounts of dolomite. As the density of barite and dolomite has some differences, gravity separation between them is usually easy. The gravity separation tests were conducted with no results obtained due to the fine dissemination size in a complex sedimentary. The magnetic separation was conducted to remove the magnetic gangues, and the results are not satisfactory as the gangue minerals such as limonite and others were low in content. Due to the fine dissemination and intimate association of minerals, and barite and dolomite contain the same group ions of Ba2+, Ca2+ and Mg2+, the results of flotation tests showed that the mineral separation between barite and dolomite by flotation means problematic. Previous studies have been conducted by several institutions but none to date has come up with a satisfactory process in dealing with the deposit. This may be attributable to: high cost of reagents; unsatisfactory performance. Therefore, the key to the flotation separation of barite and dolomite is the application of selective inhibitors. Based on previous test observations and years of extensive research experience in barite processing technology, with the new depressant TS has selectivity inhibition on dolomite developed and used, good results can be obtained by “desulfurization-barite flotation”, which allows barite in the lead-zinc tailings to a comprehensive recovery."

Jan 1, 2018

Optimising flotation designs and innovations is a complex process involving many parameters, one of which is ensuring sufficient testwork is carried out at plant level before these innovations are launched in the marketplace. This paper will describe how modern design tools are utilized, what are testwork phases at various plants and how results and observations have helped to validate and optimise flotation design innovations. Scale-up of equipment has long been the prevalent trend, but how long can it continue? Are there other means for pushing the boundaries of present technology? Some present challenges and future directions are given in the light of theoretical criteria for scale-up and how it has been applied in practice. Very large flotation cells of 300 m3 size have been installed in New Zealand, and relevant results from the metallurgical and mechanical aspects are presented and discussed. Utilization of the cell volume is also important. New innovations in the hydrodynamic domain are presented and discussed. Means to enhance flotation of coarse and fine particles are shown with results from plant testwork. Accurate control of large flotation cells is vital to optimize yields and grades. Froth image analysis and intelligent level control are presented ? again - with relevant plant results.

Jan 1, 2014

By Z. G. Li

The large-scale vibrating screen has been applied widely in coal industry and other industrial areas as a kind of important device. As vibration mechanical device, it works very hardly and works in very bad environment so that the structure of screen is damaged easily. Therefore, it is very important that how to detect the fault of structure as early as possible to make the repair schedule reasonably and economically and to avoid the body hurt and device damage. As a kind of important structure of vibrating screen, the lower crossbeam is the main carrying structure and it is easily damaged, so it is regarded as a researched object in this thesis and it is tested under the load in the laboratory. Based on the test, acoustic emission wave signals can be got-ten by modern acoustic emission testing technique. Then, the ?wavelet packet - energy? from the characteristics of acquiring signals is used as neural network input vector. In the BP network structure design, the design of a hidden layer with variable number of BP network is established. Based on the error by contrast, the best nerve number can be identified in the hidden layer. Through integrated analysis, using Levenberg-Marquard BP study algorithm, network-training errors are relatively small, the acoustic emission signal is used in BP neural network as a pattern of recognition. In Matlab6.5, neural network model identification is created and taking advantage of nonlinearity and the ability of learning and memory of Neural Network, this model is fixed by training structure of network with training samples. The work presented shows that acoustical emission signal processing and research on early fatigue fault diagnosis based on the wavelet and the neural network is viable.

Jan 1, 2014

By R. D. Alorro

Melting has become a popular pre-treatment method for municipal solid waste (MSW) incineration residues in Japan. Although the method is effective in stabilizing the hazardous organic sub-stances such as dioxin, it concentrates the heavy metals such as Zn, Pb, Cu, and Cd in a newly formed fly ash (melting fly ash). Melting fly ash is classified as a hazardous waste because of the leaching potential of these heavy metals in landfill environment. Extraction and recovery of these metals seem to be more environmentally and economically attractive than disposing the material to landfill after immobilization process. This study proposes a Carrier-in-Pulp (CIP) method as a new hydrometallurgical route to reject and recover heavy metals from fly ash. In this method, a carrier material which recovers the extracted metals is added simultaneously with fly ash to leaching solutions and is harvested from the pulp by physical separation method like magnetic separation or sieving. To demonstrate the effect of CIP method, shaking flask experiments were conducted under various conditions using NaCl solution as lixiviant and iron powder or granular activated carbon as carrier materials. In the CIP method using iron powder, more than 97 wt% of Pb and Zn were extracted from the ash to the solution phase. However, the iron powder which was harvested from the pulp by magnetic separation, recovered only Pb (more than 94%) through cementation, leaving behind Zn ions in the solution phase. Due to this problem, granular activated carbon (GAC) was considered as an alternative carrier material. Single- and multi-metal adsorption experiments using granular activated carbon were conducted as a preliminary study. Around 85% Pb and 88% Zn were recovered by GAC in the single-metal adsorption experiment, while 60% Pb and 70% Zn in the multi-metal experiment. These results showed that activated carbon was superior to the iron powder since it was able to recover both Pb and Zn through adsorption. The leaching test conducted on the residue after the CIP-Fe treatment revealed that the solubilisation of Pb was successfully suppressed to meet landfilling guidelines.

Jan 1, 2014

By G. Y. Zhou

During Zijinshan copper heap bioleaching, pyrite was leached in plenty resulting in high ferric concentration in solution. It has affected bioleaching and extraction processing greatly. It results much acid and iron in solution and bad effect to extraction processing. The paper studied the influence factors in the course of pyrite leaching and ferric ion chemical oxidation, especially studied the redox potential for copper bioleaching so as to find key factors affecting the dissolution difference between chalcocite and pyrite. The results show that the redox potential is important factor. Copper and pyrite leaching rates are 95% and 11% respectively and there is great dissolution difference between them at redox potential 700 mV (SHE). During pyrite bioleaching, the indirect action of bacteria gives priority to bioleaching cooperating with the direct attack of microbial cells attached to the mineral surface. Redox potential is determined by ratio of ferric and ferrous, ferric in solution was supplied by the way of oxidation of T. f bacteria, sufficient bacteria concentration and active character were two vial factors of controlling redox potential. It is indicated that copper can be selectively bioleached during copper bioleaching by controlling redox potential of bioleaching. The conclusion will provide theoretic foundation on balance of acid and iron during bioleaching for copper of higher S/Cu ratio. The experinment proved that bacteria activation was decreased on condition of both low pH value and intermittent aeratation during bioleaching. It resulted that the oxidation velocity of ferrous ion was decreased and redox potential was controlled. The dissolution of pyrite was depressed. It would be possible to actualize selective leaching of secondary sulfide copper ore during bioleaching process.

Jan 1, 2014

By K. D. Mehta

Copper concentrate containing complex sulphides of Cu-Ni with 14.13% Cu and 10.04% Ni besides impurities such as 0.33% Co and 0.71% Mo, is not acceptable to the copper smelters due to the smelting problems. Selective bioleaching of nickel from the concentrate can be considered an an option to make it suitable for copper smelter. Effect of elemental sulphur and pyrite on the bioleaching of Ni and Co has been investigated using a mixed culture of Acidithiobacillus ferrooxidans (A.f.) and Acidithiobacillus thiooxidans (A.t.). Parameters such as pH, temperature, particles, size etc. were optimised to understand the role of additives in the bioleaching. With 2% S at 308K, 2.0 pH, 5% pulp density and 200µm size particles while shaking at 100 rpm, 79% Ni, 41% Co and 5% Cu were bioleached as compared to the leaching of 81% Ni and 45% Co in presence of 10 wt% pyrite in 60 days; 27% Ni, 24% Co and 4% Cu were recovered in sterile experiment. The selective dissolution of nickel and cobalt as compared to copper may be explained by galvanic interaction between chalcopyrite: pentlandite / pyrrhotite. Bioleaching was facilitated by strong oxidizing conditions due to higher Fe3+/Fe2+ ratio/redox potential (ESCE) as a result of improved interaction of minerals through biooxidation of sulphur and accelerated galvanic interaction by pyrite. The mechanism of selective leaching of Ni and Co was established by XRD phase identification.

Sep 1, 2012

By A. Qaredaqi, M. Mohammadi

Wet High Intensity Magnetic Separators, for short, WHIMS are used for recovery of Iron ores with low magnetic susceptibility. A Jones patent WHIMS with "grooved plates" matrix is being used in Dry Tailing processing line in Hematite Recovery Plant at Golgohar mining & Industrial Co. for recovery of Hematite. In this kind of separators Matrices are used for increasing the Magnetic field intensity and providing high magnetic field gradient. The laboratory WHIMS in Golgohar Iron Ore and Steel research Institute is capable to provide a background magnetic field strength up to 0.85 Tesla and in presence of ‚expanded metal? matrix, magnetic field intensity could increase up to 0.9 Tesla. More than 50% of feed particles in this separator were finer than 36 micron and recovery of these particles needs more magnetic field intensity. Hence, ‚Grooved Plates? matrices with Js= 2 Tesla and 3.8 mm gap were constructed. Measurements indicated that magnetic field intensity around the matrix will increase to 1.25 Tesla. Graph of Magnetic field intensity around the matrix to background magnetic field intensity was plotted and a model with Rsquare= 0.9 was offered. In addition, magnetic field gradient and magnetic force were calculated. In WHIMS with feed top size of 150 micron, the main effective forces on separation process are the magnetic force and the hydrodynamic drag force. With assuming that the particles are smooth and spherical and the flow is laminar, Recovery of fine magnetic particles is problematic in this separator because of drag force. Considering these facts and mentioned model, finest particles that are recoverable in different magnetic field intensities were calculated. Computations illustrated that with magnetic field intensity more than 0.8 Tesla, particles as fine as 4 micron are theoretically separable but it should be noted that in practice a larger attractable particle size would be expected.

Jan 1, 2014

By D. Saramak

The proposal of the nip zone angle determination in HPGR crushing process is presented in the paper. Knowledge of the nip zone angle value, in turn, makes it possible to determine the real maximum pressing force in the high-pressure comminution. Two methods of determination of this maximum pressure were proposed and verified. The first method is based on the roll?s geometry, and the change of the HPGR chamber?s volume together with the roll rotation, while the second one considers the outlet gap width impact. Results of the nip zone angle calculations according to both methods are similar and show convergence with the real operating conditions. The verification was carried out in a piston-die press, and experimental results show that methodology of the nip zone angle determination presented in the paper has its practical confirmation. A proper determination of the nip zone border makes it possible to calculate the comminution probability of given type of material and is a basis for the HPGR crushing process modeling and optimization. Keywords: HPGR, comminution, nip zone, ore processing

Sep 1, 2012

By P. K. Fedotov

Centrifugal separation opens its new application fields in the Mining Industry. The up-to-date equipment for ultra-fine ore and concentrates grinding allows an efficient use of centrifugal concentration for micronic gold grains recovery. Moreover, advanced centrifugal concentrators are presented on the market: concentrators with continuous concentrate discharge designed both for ore and non-metallic minerals concentration process. The conducted tests proved the centrifugal concentration to be efficient process for gold recovery from finely ground concentrates and ores (less than 20 µm). Knelson concentrator application for such a fine material in different process circuits makes possible to raise the total gold recovery level of plants. In the circuits of coal plants and in course of coal slimes treatment the centrifugal concentration may be used before flotation in order to improve process performances. A centrifugal concentrator KC-CVD with continuous concentrate discharge working on 0.3 (0.5)mm fraction before flotation is

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 W. X. Yin

Electrowinning of lead from aqueous solution of PbCl2 and electrowinning of manganese dioxide from aqueous solution of MnCl2 are two research focuses in hydrometallurgy. This paper investigated a new process of simultaneous electrowinning of lead and manganese dioxide in chloride medium. The simultaneous electrowinning process in chloride solution not only can prevent chloride from liberating at anodes but also obtain two electrolysis products and decrease electric energy consumption. Diaphragm cell is used in the simultaneous electrowinning process to form separate anode and cathode compartment. The effects of temperature, HCl concentration in anolyte, NaCl concentration in catholyte and electrolysis time on current efficiency and cell voltage are studied. The results indicate that current efficiency of anode and cathode for 5 hours is 99% and 96% respectively, average cell voltage is 1. 701V, the weight ratio of lead and manganese dioxide produced at electrodes is 2. 39:1 under the optimum conditions. As anode products, manganese dioxide is ??MnO2, content of which in the products is more than 92%.

Jan 1, 2014

By R. K. Rath

The low-grade iron ore sample contains both lumps and fines. It is mostly hematitic iron ore and considerable amount of goethitic/limonitic material is present in it. The major impurities present were quartz and clay. It is observed that the iron bearing phases are poorly liberated above 300 µm and the liberation improves below 300 µm. More than 80% liberation is achieved below 106 µm. Based on the liberation data, the feed for the different beneficiation methods was prepared by stage crushed the ROM followed by grinding passing to 106µm and the ground material (-106µm) was deslimed. The underflow was subjected to various beneficiation techniques such as tabling, enhanced gravity separator (EGS), wet high intensity magnetic separation (WHIMS), and flotation and the results are discussed. All the methods studied could able to produce pellet grade concentrate with iron content of 64.5%, however, a marginal higher yield was observed for WHIMS (81%). Keywords: beneficiation, gravity, magnetic, enhanced gravity separation, flotation, low-grade iron ore, desliming

Sep 1, 2012

By Ari Kokko

Metso has a long history supplying boilers for high ash coal firing. These boilers are based on circulating fluidized bed (CFB) technology. CFB?s biggest benefit is fuel flexibility ? it can burn fuels from high moisture content to high ash content. Metso has delivered tens of CFB boilers burning waste or high ash coal starting on 80?s. Some of the boilers have been in operation twenty years meaning that there is a long term experience from these plants available. This feedback includes boiler performance and maintenance issues of the boiler. Metso is also delivering coal washing plants to improve coal quality, i.e. reducing ash content of the coal. The idea to combine coal washing plant and CFB boiler was made up two years ago in Metso. Up-coming legislation of coal washing and restrictions for washery reject land-filling in India are good drivers for this kind of concept. Pre-study of this kind of concept led to the conclusion that coal washing process can be fine-tuned so that reject?s calorific value is only 1100 kcal/kg and that was set as a target for boiler design. Metso shipped 200 tons of washery reject to its own research center located in Tampere Finland. First a wide range of fuel characterization tests were done in lab-scale and after that one week test run in 4 MW CFB pilot boiler was done. Test run proved that 1100 kcal/kg can be fired without any support fuel with special boiler design. Test run results gave a good set of data regarding combustion efficiency, emission performance and boiler dynamic behaviour when burning this kind of fuel. These results are introduced in this paper. This paper introduces also the CFB boiler concept for washery reject firing including boiler plant, fuel and ash handling systems and flue gas cleaning system. Power plant can be integrated with coal washing plant so that boiler size matches with washing plants c

Sep 1, 2012

By S. Dwarapudi

Pelletizing of Indian chromite ores is more challenging due to their high refractory nature. High Cr/Fe ratio and high MgO content in these ores demand high firing temperatures and longer firing cycles but often result in low strength fired pellets. Aim of this study was to develop cold bonded chromite pellets for smelting in submerged arc furnace (SAF) from chromite fines using suitable binder that induce less gangue into the pellets but cures quickly. Different binders were studied through laboratory pelletizing experiments for their suitability for cold bonding the pellets. As result, a composite binder comprising organic and inorganic binding agents was found to be suitable and pellets made from the same were tested for their low and high temperature behavior. High temperature reduction studies revealed that pellets were resistant to disintegration up to 1200 °C.

Sep 1, 2012

By A. Vidyadhar

Using pure quartz and hematite minerals, the adsorption mechanism of mixed cationic/anionic reagent schemes was investigated through Hallimond flotation studies. The flotation response of quartz and hematite independently with cationic and anionic collectors as well as with mixed cationic/anionic collector systems is assessed. The flotation response as a function of pH and collector concentration was investigated. The single mineral flotation tests in the presence of anionic collectors, quartz does not respond to flotation, but the C12 amine flotation of quartz was observed to be pH and concentration dependent. It was observed that hematite flotation recovery is maximum at acidic pH with sodium dodecyl sulphate (SDS), neutral pH with oleate, and at basic pH about 9.5 with C12 amine. Flotation results with both quartz and hematite indicate an increased adsorption of cationic collector in the presence of anionic collector apart from its own co-adsorption. The incorporation of oleate in between C12 amine molecules decreases the electrostatic head-head repulsion and thereby increasing the adsorption of C12 amine due to attractive tail-tail hydrophobic bonds, besides forming a closely packed adsorbed layer enhancing the hydrophobicity. The increase in oleate concentration beyond C12 amine concentration leads to the formation of soluble C12 amine-oleate complex / precipitate and the adsorption of these species decreased the flotation since the alkyl chains are in chaotical orientation with a conceivable number of head groups directing towards the solution phase. Keywords: quartz, hematite, adsorption, mixed collector system, flotation, zeta-potential

Sep 1, 2012

By R. S. Wang

The flotation of pyrite which be pretreated by electrochemical ways under external controlled voltages in different pH is explored. The floatability of pyrite is increased indistinctively after being pretreated in acidic and xanthate environment; Whereas, it is increased obviously between 400~800 millivolt in alkaline and xanthate condition. The reason for higher recovery of pyrite is that oxida-tion reaction, which results in S0 and S02, takes place on its surface, and that ethyl xanthate is oxi-dized into dixanthogen. In the meantime, the kinetics and mechanism is also studied.

Jan 1, 2014