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By G. Kumar

Water for domestic consumption is an essential right of society, which must be over secured. Water reclamation and reuse provides a unique and viable opportunity to augment traditional water supplies. As a multi-discipline and important element of water resource development and management, water reuse can help to close the loop between water supply and wastewater disposal. Effective water reuse requires integration of water and reclaimed water supply functions. During the coal mining activities, large quantities of water get contaminated and loses its potability characteristics. On an average, in coal mine operation, each coal mine discharges effluents at a rate of nearly 0.5 MGD and thereby wastage of nearly 50 MGD of water takes place per day from the famous Jharia Coal Field of the Dhanbad District. In this paper, attempt has been made to control the extremely high turbidity of mine waste water by using different coagulants and it is observed that ferrous sulphate is the most effective coagulants followed by alum, ferric sulphate and lime. Also combinations of coagulants are used for getting the optimal results. Further steps were also discussed to make this water potable and a scheme of low cost water supply system of mine waste water has been suggested under the Water Management Strategies. Keywords: potability, turbidity, coagulants, water management strategies

Sep 1, 2012

By Leming Ou, Hongqiang Li, Li Zeng, Qiming Feng, Yiping Lu, Guofan Zhang

"The entrainment of sericite, especially in the presence of hydrophobic microcrystalline graphite, leads to the poor flotation selectivity of microcrystalline graphite ore. In this paper, it was attempted to reduce entrainment of sericite, selective flocculation of microcrystalline graphite using polyethylene oxide (PEO) was studied. For the sake of flocculate microcrystalline graphiteselectively, flocculation tests of microcrystalline graphite and sericite single mineral were conducted.To investigate the effect of selectiveflocculation of graphite on entrainment of sericite in microcrystalline graphite flotation, batch flotation tests of graphite single mineral and artificial mixtures were conducted; theflocculationselectivity of PEO of different molecular weight (M.W.) was alsocompared inartificial mixture flotation. Inthe end, the structure of flocs in different particle size was studied by sieve analysis and microscopic observation. The resultsindicated that PEO of molecular weightone million andtwo million could selectivelyflocculate the microcrystalline graphite and reduce the entrainment of sericite at a lower dosage; further increasingof the dosage of PEO(M.W. ?two million) led to hetero-flocculation between graphite and sericiteandmadethe ash content of concentrate increase again."

Jan 1, 2014

By Kaioeng Wang, Qi Liu, Yahui Xiang

"In the differential metal sulfide ore flotation it is desirable to replace the toxic inorganic depressants with environmentally benign chemicals. Chitosan, as a natural and non-toxic polymer, has been proven to be an efficient depressant for chalcopyrite while allowing galena to be floated by xanthate collectors. However, the poor solubility of chitosan limits its potential applications as the flotation could only be carried out at about pH 4 where chitosan is soluble. A carboxymethyl derivative of chitosan, named N-carboxymethyl chitosan (N-CMC), was synthesized by substituting the amino groups of chitosan with carboxymethyl groups. The substitution significantly improved the solubility of chitosan. The structure of N-CMC was studied and compared with chitosan via Fourier transform infrared spectroscopy (FTIR). Flotation tests were performed on single minerals and mineral mixtures (with weight ratio of 1:1) with the addition of appropriate amount of potassium ethyl xanthate (KEX) and N-CMC. The solution pH was varied from neutral to alkaline. The flotation concentrates and tailings were collected and analysed for the contents of copper and lead. FTIR measurements showed that new peaks of C=O stretching of -COOH and N-H deformation of -NH- appeared in N-CMC, which indicated that the carboxymethyl groups were introduced and the amino groups were the sites for the substitution. Flotation results indicated that N-CMC could depress either chalcopyrite or galena depending on the pH. The results were not affected by the sequence of KEX and N-CMC addition. Therefore, N-CMC is potentially useful in Cu-Pb sulfide separation following a bulk Cu-Pb flotation. The N-CMC was also found to have surface cleaning functions, and was able to remove contaminating copper ions from galena surfaces. Therefore, its application in sulfide ore flotation is expected to be more robust than the original chitosan."

Jan 1, 2014

By Chris Plackowski, Bruckard. Warren J., Anh V. Nguyen

"Enargite is a significant penalty mineral in the copper industry and its separation from many copper sulfides by flotation is difficult. The separation may be crudely achieved using selective oxidation techniques or through the use of pulp potential control. This paper summarizes our latest contributions to a better understanding of enargite surface electrochemistry and hydrophobicity. Oxidation, roughness, hydrophobicity and species formation on the surface of natural enargite were examined by a novel experimental approach that combines electrochemical techniques, atomic force microscopy, X-ray photoelectron spectroscopy and droplet evaporation tensiometry. It allows for synchronized electrochemical control and examination of the oxidative surface morphology, speciation and hydrophobicity of enargite at pH 4 and pH 10. At low pH, surface layer formations consisting of metal deficient sulfide and elemental sulfur were identified associated with a limited increase in roughness and heterogeneous distribution of surface species produced by initial rapid dissolution of Cu, followed by diffusion limited surface layer deposition. At high pH, a similar diffusive mechanism associated with oxidation products consisting of copper sulfate and hydroxide and a significant increase in surface roughness were established. Receding contact angle measurements showed no significant difference in the contact angle on a surface oxidized at pH 10 and the freshly polished surface. Contact angle increased from 46° on the polished surface to 59° after oxidation at pH 4. Competing effects of hydrophilic copper oxides and hydroxides, and hydrophobic species of elemental sulfur on the mineral surfaces under oxidizing conditions at pH 4, and the change in surface roughness at pH 10, contribute to the changes in enargite hydrophobicity under electrochemically-controlled oxidation conditions. Most likely, both surface species and surface roughness produced by oxidation are critical to the changes in the wettability of enargite and other sulfide minerals."

Jan 1, 2014

By M. R. Hosseini

Among all gravity concentration methods, Shaking-table is the most effective one from the metallurgical point of view. In this study, Shaking-table was used for concentrating a manganese ore sample from Ghasem Abad area in Kerman, Iran. Experiments were designed by using L8Taguchi design with five variables and each variable in two levels. The influence of each variable and their interactions on the operation of the device was studied. The variables under investigation were: table slope, table frequency, water flowrate, feed rate, and particle size. The manganese concentrate grade and recovery were used as response variables. It was shown that water flowrate, table slope, feed rate, and particle size are the significant variable on concentrate grade; while, all the variables influence manganese recovery.

Jan 1, 2014

By Y. G. Seredkin, A. A. Vasiliev, A. Y. Senchenko, A. V. Aksenov

"The valuable materials resulting from the processing of gold-bearing ores are often refractory to direct gold recovery through cyanidation. There are multiple methods for chemical liberation of gold prior to cyanidation such as pressure and biological oxidation as well as atmospheric oxidation which is typically used in combination with physical activation of material by ultrafine grinding such as the Albion ProcessTM. This paper will examine the data from process testworks carried out to estimate the efficiency of the Albion Process™ for the oxidation of materials with a wide composition range prior to cyanidation. The data will be compared to that obtained by direct cyanidation of the feed (without oxidation) and from the testing of pressure oxidation on the feed prior to cyanidation. Albion Process™ tests were conducted in Institute TOMS with participation of Glencore Technology Pty Ltd (Australia). Refractory concentrates obtained from the ores of several Russian and CIS deposits were used as feed for the testing. These concentrates were also subjected to a material composition study and testing using conventional recovery methods. The resulted test data make it possible to perform an integrated assessment of process properties for materials with different compositions, compare performance of various process flowsheets for the materials under study, and conclude on efficiency of Albion Process™ application for gold recovery from refractory materials different in their composition.INTRODUCTION It is often the case that gold ore concentrates are refractory to gold recovery by direct cyanidation. This refractory nature is as a rule attributable to fine gold dissemination in minerals, most often in pyrite and other sulphides, as well as to the increased amount of components impeding cyanide leaching of gold due to cyanide consumption and reducing process conditions. The refractoriness of the concentrates results in low gold recovery values when conventional cyanidation technology is used. In this context, various additional processes are applied to breakdown such refractory sulphide concentrates, i.e. mechanical breakdown (fine and ultrafine grinding), chemical breakdown (atmospheric oxidation, e.g. Leachox, acid-oxygen oxidation, pressure oxidation – POX, bacterial oxidation – BIOX), and thermochemical breakdown (various roasting methods). Such breakdown processes allow for increase in recovery of finely disseminated gold during the downstream cyanidation, however, their application is cost-intensive and does not always ensure economic benefit."

Jan 1, 2018

By Ashiwani Kr Gupta

The floatability of coal is affected by the presence of dissolved inorganic ions in plant process water. Water quality is characterized in terms of conductivity, hardness, turbidity and composition of oil. These quality indices are correlated with coal flotation performance for three different water named, ?R&D laboratory tap water?, ?process untreated water? from West Bokaro wahsey-2 Tata Steel, India and ?process treated water? after passing laboratory developed treatment process. The study clearly indicated that a significant quantity of clean coal is being lost due to poor process water quality used in the flotation process. The laboratory investigations showed that if these dissolved salts and suspended solids are reduced to even 50%, a clean coal yield improvement by minimum 5%~10% at the same ash level could be expected. Therefore, the conventional practice of water recycling though a thickener or a tailings pond needs a complete re-look. The water treatment process for recycled water has also been discussed for improving the process water quality as well as enhancement in flotation performance efficiency.

Jan 1, 2014

By T. Sun, J. Kou, C. Sun, D. Gong

"HPGRs (high pressure grinding rollers) have demonstrated higher energy efficiency than conventional comminution equipment due to their application of particle-bed breakage mechanism. In the past decades, a large number of studies have been conducted to understand the characteristics of particle-bed breakage, however, few of them concerned the difference between single-particle and particle-bed breakage in compression comminution. This comparison is able to demonstrate possible advantages of particle-bed against single-particle in a breakage event due to the isolation of the effect of force loading mechanism. The present study investigated progeny fragment size and energy efficiency of these two breakage methods at variable energy inputs and particle sizes. The results show that at low energy inputs of around 0.25 kWh/t, the numbers of fines resulting from the two breakage methods are very similar. However, at higher energy inputs of around 1.0 or 2.0 kWh/t, particle-bed breakage generated significantly more fines. From the perspective of newly generated surface energy, particle-bed breakage is obviously more energy efficient than single-particle breakage at energy inputs between 1.0 and 2.0 kWh/t. It was also found that HPGRs demonstrate high energy utilization rate in generating new surface energy within their typical range of specific energy input. INTRODUCTION Rock comminution is an important and energy-intensive process in mining operations. Nowadays, decreasing head grade and mineral liberation size of ore deposits greatly increase the energy cost of comminution process. HPGRs have been successfully applied in the mining industry to improve the energy performance of comminution circuits. Typically, 10 to 30% of energy saving can be achieved due to the application of HPGR (Wang et al., 2013; Casteel, 2005; Günter et al., 1996)."

Jan 1, 2018

By E. Burdukova

This paper explores the relationship between the rheological behaviour and mineralogical nature of three different natural ore types. Rheological measurements performed here on Platreef, Kimber-lite and Norseman-Wiluna ores are correlated with the variation of phylosilicate mineral content in these ores and the corresponding physical properties of selected phylosilicate mineral groups. Preliminary results show that the clay mineral group (talc) has the least effect on both Bingham yield stress and viscosity of the three ore slurries tested, whereas the serpentine mineral group has a dramatic increasing effect on the Bingham yield stress especially at very low solid volume fractions. The Bingham viscosity of the mineral slurry appears to be the most influenced by the presence of the swelling clay mineral group (smectite). Significant increases in either Bingham yield stress or viscosity due to elevated contents of these problematic phylosilicate mineral groups are likely to cause negative effects on the processing and manageability of mineral slurries but it is unclear which is likely to have a more detrimental effect.

Jan 1, 2014

By A. Akcil, O. Celep, C. Erust, E. Y. Yazici1, H. Deveci1

"Recycling of WEEE has already gain prime importance from both environmental and economic point of view. For the recovery of metals from e-waste, many conventional physical, bio/hydrometallurgical and pyrometallurgical processes are proposed. Economic potential of e-waste is mainly driven by its precious metal content. Physical separation methods (e.g. electrostatic, magnetic, eddy current and gravity separation) exploit the differences in the physical properties of metals and non-metals. Physical separation methods are simple and economically sound but they suffer from metal losses and ineffectiveness at fine sizes. Hydrometallurgical processes are promising owing to their relatively low cost, reduced environmental impact, potential for high metal recoveries and suitability for small scale applications. Hydrometallurgical processes can be developed for selective extraction of base/precious metals using suitable reagent systems. Sulphate-based leaching with a suitable oxidant (e.g. H2O2, O2, Fe3+) is effective for copper and other base metals. After removal/recovery of base metals, precious metals can be easily extracted using various lixiviants including thiosulphate, thiourea, cyanide and chloride. However, further research is required to develop new, cost effective and environmentally friendly processes and/or refine existing ones for leaching and, in particular, downstream processes. INTRODUCTION Electrical and electronic equipments are indispensable to modern societies with numerous applications in the field of medicine, transport, communication, education, security and environmental protection. With technological developments and innovations, the replacement of old equipment leads to ever fast accumulation of waste materials such as waste electrical and electronic equipment (WEEE or e-waste). People are upgrading their mobile phones, computers, televisions, audio equipment and printers more frequently than ever before (Babu et al., 2007; Lee et al., 2007). With the rapid growth in technology today, the life span and utilisation period of most electronic and electrical equipment has been reduced considerably with concomitant generation of huge amounts of WEEE over the past several decades. According to statistics presented by Balde et al. (2015), total WEEE produced around the world was 41.8 million tonnes in 2014 and expected to rise to approximately 50 million tonnes by 2018. Kumar et al. (2017) estimated that annual growth rate for the WEEE stream is 3–5% (Singh et al., 2016). The aim of this paper is to provide an overview of physical separation and hydrometallurgical methods available for the treatment of WEEE."

Jan 1, 2018

By Wei Sun, Chengwei Li, Zhiyong Gao, Yuehua Hu

"Grinding for mineral liberation is a prerequisite for a successful flotation separation. Different grinding media produce mineral particles with different morphologies and surface properties. In this study, the surface physicochemical properties of fluorite particles produced by ball and rod mills were systematically investigated through single mineral flotation experiment, wettability measurement, X-ray diffraction (XRD) test and scanning electron microscopy (SEM) observations. The XRD observations reveal that the surface exposure degree for both mill particles follows the order {111} > {110} > {100}. The difference lies in that the rod mill ones have a higher exposure of more reactive {110} and {100} surfaces, leading to a stronger interaction with the collector. The difference also leads to their higher elongation and lower roundness values of rod mill particles which are beneficial for the particle-bubble attachment by shorting the induction time. The wettability and flotation results show that the rod mill ones have a lower critical surface tension and a greater hydrophobicity when treated with the collector solution and accordingly perform a higher flotation recovery. This work, for the first time, revealed the importance of the exposure of crystal surfaces in determine the shape factors and reactivity of the mineral particles and will help provide guidance for optimizing flotation separation and particle surface modification. INTRODUCTIONFluorite (CaF2) is the most important source mineral for producing F-based chemicals and materials which are widely used in industrial, environmental, and medical fields [1, 2]. In ore deposit, there are two kinds of occurrence forms of fluorite mineral. Firstly, the fluorite mainly coexisted with the gangue minerals like calcite (CaCO3) and quartz (SiO2). Because of their similar density and fine-grained dissemination in ore deposit, ball mill grinding before flotation separation has been widely applied to produce relatively fine particles [3]. Secondly, the fluorite is often associated with other valuable minerals with higher relative density such as scheelite (CaWO4) and cassiterite (SnO2). Due to their obvious density differences and coarsely grained distribution in ore deposit, rod mill grinding before gravity separation has been usually used to produce more uniform particles and avoid over-grinding [4-6]. After the gravity separation, a flotation separation is also employed to beneficiate the fluorite [7]."

Jan 1, 2018

By D. Steele, B. Ndlovu

"Adequate characterisation of clays is becoming increasingly important as operating mines move into areas of more complex ores. The processing therefore needs better mineralogical characterisation to identify problematic ores for better planning before issues arise. While a number of instrumental mineral characterisation methods are available, X-ray Diffraction (XRD) is widely recognised as perhaps the best technique for the identification and quantification of minerals, particularly clays. When an appropriate sequential and systematic sample preparation and treatment protocol is employed with instrumental XRD analysis individual clays can be uniquely identified, and the proportions of interstratified clays can also be quantified. The effect of sample preparation on the XRD analysis and identification of clays was investigated in this study. The results showed that sample preparation protocol is indeed critical to accurately analysis and characterisation of clays. For example, both dry grinding and micronizing affected the degree of crystallinity of kaolinite leading to the formation of reactive surfaces or changes in the physicochemical behavior. It was also found that the apparent degree of preferred orientation in platy minerals correlates directly with the amount of force/pressure applied during the preparation of backfilled powder samples. This work showed that manual preparation can produce highly variable peak intensities especially with minerals that show any preferred orientation. KEYWORDS Clay; XRD; kaolinite INTRODUCTION Clays are important in our life and they have numerous applications in modern world from cosmetics to environmental remediation. Therefore, clays have been extensively investigated for many years. Adequate characterisation of clays is becoming increasingly important as the mineral processing industry faces more complex mineralogy with the need for better mineralogical characterisation to identify problematic ores and plan accordingly. In most studies, X-ray diffraction (XRD) method has shown the unique capability to characterise mineralogy, especially for the fine grained size materials. The XRD technique is particularly diagnostic for clays. It is known that under ideal conditions, the peak intensities of an XRD diffractogram are proportional to the concentrations of individual minerals present in the sample. Hence, the qualitative mineralogical data obtained from XRD can be quantified, using either the internal or external standard methods. However, it is also known that clays are particularly sensitive to the influences of sample preparation method due to their physical characteristics (e.g. fine grain size, morphology, relative physical softness, crystallinity, thermal sensitivity) that could be destroyed by inappropriate preparation prior to the analysis. Thermal and mechanical treatment and grinding of clays can change their crystalline structure, and consequently, their characterisation results by XRD analysis. The behaviour of clays in grinding has been widely studied, especially for kaolinite (Miller and Oulton, 1970, Milocevic et al., 1992, Tomasevic-Canovic et al., 1992). With prolonged grinding time, the crystallinity of the clays can decrease (Filipovic-Petrovic et al., 2002). It has been shown that grinding may gradually cause the loss of hydroxyl ions of kaolinite (Gonzalez Garcia et al., 1991)."

Jan 1, 2018

By Lei Wang, Qi Zheng, Xiao-kui Che

"The wastewater emitted by gold chemical industry contained vast of different heavy metal ion, such as Zn, Cu and Ni etc. Among them Zn is the main ion in the waste water which causes the serious environment pollution. A method of preparing a kind of resin which is used for the removal of Zn by magnetic adsorbent was developed and was applied in practice. This adsorbent is a chitosan made of a kind of Fe3O4-chitosan modified by epichlorohydrin. The adsorption capacity of the absorbent and it was concluded that under the laboratory conditions, the maximum adsorbing capacity of this adsorbent could be 287.58 mg/g. The absorbent was also applied in the wastewater emitted by a gold industry in Shandong province. Its performance was tested and the result showed that the concentration of Zn ion in the wastewater was reduced from 0.58 mg/L to 0.0174 mg/L. What is more, the adsorption rate could be more than 97% when the dosage was 100L/m3 after adsorbing for 1h. KEYWORDS Selective, preparation, laboratory experiments, industry experiment, comparation INTRODUCTION Currently, most gold chemistry use cyanide to leach gold ore. Many different metals participate to this reaction besides the gold ion in this processing, so that the composition of the water is very complex. The waste water emitted by gold chemistry industry contains large amount of heavy metals. Definitely, if it was discharged without any treatment, the water would threaten the environment. The recuperation of any ion in the water would mitigate the pollution. Ion exchange resin, which is an effective material to do the water treatment with low cost, became widely applicated in this field [Yu-jiao Wang,2013]. Different kinds of resin were developed and the influence factors such as pH, adsorption properties and selectivity for different ions were investigated [CA Cruz et al,2018; PawanKumar et al.2016; Y Zhang, et al,2010; and ShengingSun, Aiqin Wang, 2006;]. The waste water mentioned in this article has a high Zn concentration, so a magic resin for Zn adsorption selectively we designed was used to manage this water. And the recovery of Zn could not only contribute to pollution abatement but also a best way to settle a dispute to the short of Zn resource. So the article mainly describes the preparation and the application of a kind of magnetic adsorbent used for the removal of Zn both in laboratory and industry. The aim of this article is to compare the effect of this resin in industry and laboratory?"

Jan 1, 2018

By Sergey S. Gudkov

In the current climate of changing the approach to mining and treatment of mineral resources, processing technologies are being developed that require little maintenance and are economically as well as ecologically sustainable. This may also involve the development of entirely new ways of ore processing. One promising approach is to use bioleaching for the pretreatment of gold refractory ores to cyanidation. Capital costs for vat bioleaching of concentrates and ores are very high and cannot be applied for small or medium-size deposits. IRGIREDMET JSC carried out bio heap leaching test work on refractory ore samples from three Russian deposits. Following this biological treatment a combination of flotation, vat bioleaching, and cyanidation are used to recover gold. After heap bioleaching, gold recovery was 75-80 per cent. It was found that efficiency of heap bioleaching process depends on ore feed size. High duration of this process is another feature and it lasts for about a year. This process can be also used for carbonates in the combination with other process during which acid generation occurs. The results of our studies have shown that this technology is amenable for refractory gold ores. Its introduction allows an increase gold recovery and to solve a number of environmental problems. Keywords: heap biooxidaton, the refractory of the ores, the degree of oxidation, arsenopyrite, pyrite, CIL

Sep 1, 2012

By J. J. Lui

Surfactant plays a critical role in many industrial processes such as petroleum, mining, environment and food processing, and daily life. For ionic surfactant systems, adsorption of surfactant at oil-water interface imposes a net charge to the interface. The nature and magnitude of the charges at the oil-water interface depend on charge characteristics of surfactant molecules, concentration of surfactant and solution pH. In our previous study, zeta potential measurement of hexadecane drop-lets in industrial process water was shown to be a simple, yet powerful method for identifying various types of ionic surfactants present in the aqueous system. In this paper, the site-binding model was applied to prediction of zeta potential of oil droplets in aqueous solutions containing a mixture of cationic and anionic surfactant molecules. The total number of interfacial sites for various types of surfactant involved was determined by applying the Gibbs adsorption equation to the measured interfacial tension-surfactant concentration profiles. The distribution of various types of surfactant molecules at the interfaces was evaluated by Langmuir isotherm constants. With the ionization constant of surfactant taken from the literature, the predicted zeta potentials of oil droplets in surfactant solutions from site binding model were shown in a reasonable agreement with the measured zeta potential values.

Jan 1, 2014

By V. A. Chanturiya

The results study the minerals oxidation were obtained by us during the methods of microscopic, FT-IR spectroscopic, XRD and chemical analyses of sulphides in tailings of copper-nickel wastes in Kola peninsula. Sulphide minerals begin to oxidize already at the stage of stockpiling and initial stages of storing. The proportion of non-ferrous metals and magnesium oxide increases with time, calcium partially precipitating in the form of gypsum. Comparison of heavy metal contents in pore solutions in cur-rent and stale copper-nickel ore concentration tailings has revealed a significant difference in practically all the parameters. The lower metal contents in current tailing pore solutions (by 5~30 times) are probably due to the presence of float reagent residues blocking oxidation. Much lower concentrations of magnesium and calcium can be accounted for by the difference in kinetics: the rate of sulphide oxidation at this stage is much higher than that of solution interaction with non-metallic minerals as the result of which the solid phase ? solution equilibrium is not achieved. It is generally believed worldwide that it the mining wastes with acidic pore solutions that pose the greatest hazard for the environment. Our findings suggest that although the solution pH in all the samples is higher than 7.8, the contain heavy metal concentrations by far exceeding permissible values. The direct determination of the total and silicate Ni contents in the tailings from current production and in storage tailings has shown that both sulphide and silicate Ni forms occur in tailings. However, the role of silicate Ni is much larger in the storage tailings. The average silicate Ni content accounts for 10% of the bulk Ni content in the current tailings and it increases to 40% in the storage tailings. Thus, the storage tailings are marked not only by sulphide oxidation and the removal of water-soluble sulfates, but also by the interaction of sulfates with the silicate matrix. Although complete equilibrium is not achieved even within 30 yr under polar-region conditions, the major part of the Ni in fine-grained fractions passes into silicate form. The probability of Ni transition to the silicate form directly correlates with the dispersion of the material and the amount of chemically reactive serpentine and hydrochlorite. The migration of Ni as sulfates and its precipitation by chemically active silicates distorts the distribution of this component in the coarse- and fine-grained fractions that are typical of tailings from the current production of copper-nickel ores. On the one hand, the variation of the mode of Ni occurrence in storage tailings lowers the value of technogenic raw materials as a source of this metal.

Jan 1, 2014

Nowadays, the more successful plants are those who have adopted effective and efficient strategies to optimise their plant operation. As the ?heart of the plant? could be viewed as the mil-ling/grinding area, one of the key steps in plant optimisation is, therefore, ensuring the mill is operating properly. In the past, when primary, secondary and tertiary crushers fed material directly to large ball mills, the energy efficiency of the concentrator was determined for the most part by the ball mill operation, whereas now the energy efficiency of a plant often rests largely on the semiau-togenous grinding (SAG) mill operation. As a result, mines have shifted their emphasis in optimization from ball mills to SAG mills. The grinding mill?s energy efficiency essentially depends on ore characteristics and the discharge rate of broken particles, which in turn depends on how efficiently the discharge pump (grate and pulp lifters) operates. The essential function of pulp lifter being to transport the broken material and slurry out of the mill, its design optimization therefore affects the discharge capacity (or mill throughput) of AG and SAG grinding mills. This paper will discuss how the optimised design of the pulp lifter/ discharger has helped to eliminate material transport issues such as flow-back and carry-over of slurry and pebbles to in-crease the energy efficiency of SAG mill using the actual operational data.

Jan 1, 2014

By Yang Xiao, Zhang Yimin, Bao Shenxu, Liu Chun

Stone coal is a unique vanadium-bearing resource in China. Many techniques, such as salt roasting-water leaching, blank roasting-acid leaching, direct acid leaching etc. have been developed for vanadium extraction from stone coal. The vanadium leaching rate can reach 74.9% for stone coal from Jiangxi, but only about 27% of vanadium is leached for Hubei ore by applying salt roasting-water leaching technique. This paper investigats the vanadium occurrence in stone coal by microscope observation and electron probe, and compares the minerals components of stone coal from Jiangxi and Hubei. Although most vanadium exist as an isomorphism by replacing Al(III) from dioctahedral structure in mica group minerals in stone coal from two regions, the free vanadium is remarkably abundant in Jiangxi stone coal than in Hubei stone coal, which results the fact that vandium is relatively readily extracted from former. Moreover, the content of calcite in Hubei stone coal is much higher than that in Jiangxi stone coal. Calcium can react with V2O5 to form water insoluble calcium vanadates during roasting and this may be the reasone why the water leaching rate of vanadium is low for Hubei ore. Acid leaching is more beneficial to the vanadium leaching but other extra methods, such as adding aid-leaching agent and/or increasing acid concentration is need for the ore where vanadium is embeded firmly. This study can effectively guide the selection of vanadium extraction techniques for stone coal from different regions.

Jan 1, 2014

By G. Demi

The biggest chromium mineral processing plant in Albania is Bulqiza plant. It has been in operation for more than 20 years, treating low-grade chromium ores grade 20 ? 26 % Cr2O3 and producing chromium concentrates grade 48 ? 50 % Cr2O3. About 2 million tons of tailings with 13 % Cr2O3 content are stocked in a dam close to the plant. Mineral processing of low-grade chromium ores with less than 16% Cr2O3 content is unprofitable because the mining expenses are high comparing with the current market prices of chromium concentrate. Recycle and enrichment of existing tailings is profitable, because there are no underground mining expenses in this case and because that this kind of raw material does not need expenses operation of crushing and grinding. The existing plant is in operation for more than 8 years treating existing tailings as raw material. Grade of concentrate in the value 40 % Cr2O3 and Cr2O3 recovery in the value 30-35% in the plant are considered low. The main reason of low concentrate grade and recovery is high content of particles under 100 microns, the slimes, in raw material. In the paper is described the study carried out to improve enrichment of the tailings, as well as analyses of existing process, raw material and products. It is concluded that majority of lost is present in the slimes which are not separated in existing spiral separators and shaking tables. Basing in the study is composed the new flow sheet of recycling and concentration of the tailings to produce chromium concentrate grade 41 ? 42 % Cr2O3 and recovery 60 %, decreasing in this way the concentrate production cost two times. In the paper are presented the tests and results of concentration of particle size fraction under 100 microns, using gravimetric, magnetic and flotation methods, as well as equipment and machines suitable for slimes treatment and concentration.

Sep 1, 2012

By Dmitriy Makarov

The paper presents the modeling and analysis of oxidation of pyrite copper-zinc ore samples from the Letnee, Yaman-Kasy and Valentorskoye deposits. It is found, that the oxidized samples contain copper and zinc sulfates that are leached under the sample and water contact. It is shown, that sulfide floatability is decreased by the longer-term oxidation.We advise to improve nonferrous metals recovery by joint leaching and ultrasonic treatment of oxidized compounds. Study of the geotechnological processes of non-ferrous metal extraction, on the basis of two copper-zinc ore deposits shows, that heap leaching is of little use for the ores of the Letnee deposit. Leaching results for the Yaman-Kasy ore showed more promise.

Sep 1, 2012