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By Z. M. Wang

A large scale a polymetallic mine in north China is a refractory ore containing many useful com-ponents: W, Mo, Cu and Fe. Mineralogical investigation shows that the deposit is a quite complex one due to fine disseminated size and unevenly distribution of valuable, intergroth of sulphide and tungsten minerals, concurrence of scheelite and calcium minerals. Based on ore characteristic, a flowsheet is used by the floatation processing of sulfide minerals superior to scheelite. Bulk sulphide flotation is used in sulphides. Mo and Cu are floated in sequence after sulphides regrinded. Tungsten mineral is floated using combined depressant that is an effective depressant to gangue, and can improve the grade of rough tungsten concentrate. Compound depressant has high effective in removal of collector in gangue and sulphide, and tungsten is activated also. High quality of tungsten concentrate is obtained at satisfactory recovery. The test production obtains Mo concentrate with grade of 48.16%, recovery of 81.43%; W concentrate with grade of 66.47%, recovery of 78.19%; Cu concentrate with grade of 23.14%, recovery of 56.6%; Fe concentrate with grade of 67.33%. The valuable metals are recovered comprehensively and well techno-economic index is obtained. The mine enterprise profit is increased greatly.

Jan 1, 2014

By Jingzhong Kuang, Zheyu Huang, Chuanzhou Guo, Pengfei Liu

"In this paper, scheelite and scheelite coated with Pb2+ (SC) were synthesized by chemical precipitation with the help of ultrasonic. The role of the Pb2+ on scheelite was evaluated. Additionally, the dissolution behavior of minerals and the adsorption mechanism of collectors were investigated systematically via SEM, XRD, EDS. The results indicate that the ultrasonic cavitation can promote the formation of scheelite with large particle size and high crystallinity. Due to the exchange of WO4 2- and OH-, the dissolution of scheelite are not in a 1:1 equivalent amount by chemical formula and the concentration of WO4 2- is higher than that of Ca2+ in the solution because Pb2+ promotes the transfer of WO4 2- from scheelite surface into the solution. The dissolution of scheelite is an endothermic reaction and its enthalpy reaches the maximum value of 692.59J·mol-1 at pH=8~10. But the coating of Pb2+ changes the thermal effect of scheelite in the solution and the dissolution of SC is an exothermic reaction with the dissolution enthalpy of -262.30 J·mol-1. At pH=8~10, the adsorption capacity of sodium oleate and salicylhydroxamic acid on the surface of SC is higher than that of scheelite which delivers that Pb2+ contributes to the scheelite surface dissolution and enhances the adsorption of collectors on the mineral surface, thus achieving activation.INTRODUCTIONIn modern society, tungsten is a type of quite important rare metal and also a strategic resource. Because of its low vapor pressure, high melting point, good electrical and thermal conductivity properties, it is widely applied in high-temperature technology, lighting, machine and engine construction (Zhao,Z.W, 2013; Yan, W, 2017; Ilhan, S, 2013). Both scheelite and wolframite are the major tungsten deposits. With the depletion of easily-processed wolframite, scheelite has drawn a great deal of scientific and industrial attention. Scheelite can be recovered by flotation due to the metathesis of polarity and chargeability on minerals surface via adding regulators and collectors."

Jan 1, 2018

By R. S. C. Smart

Surface chemical factors, including the balance of hydrophobic (e.g. collectors) and hydrophilic (e.g. oxidation products, precipitates) species, are major control determinants in flotation rates of specific minerals and therefore grade and recovery. There are a number of challenges involved with the surface analysis of different mineral phases from process streams in a flotation facility. The first is to collect samples that are representative of the process and retain their surface chemistry prior to introduction into the instrument. The second challenge in studying the surface chemistry of specific minerals is to find reliable methods of mineral phase recognition. In surface analysis of mineral particles, confident mineral selection can be difficult with many multi-metal minerals and with precipitated, adsorbed, reacted and contaminant species in the outermost molecular layers. The third challenge is to provide a statistical surface analysis of multiple grains of the same mineral. Methods to achieve these aims are described. Principal component analysis (PCA) of ToF-SIMS data provides improvement in phase recognition, particle selection and associated variations in surface species. Specific examples from both lab and plant operations, demonstrate that this technique can be utilized to differentiate surface chemical factors promoting (hydrophobic species) or inhibiting (hydrophilic species) flotation. A study of copper ion transfer (inadvertent activation) from chalcopyrite to pyrite and sphalerite clearly identified a statistical difference in copper intensities between the sphalerite and pyrite phases corresponding to their flotation response. The PCA analysis applied to concentrate and tails samples collected from the Inco Matte Concentrator demonstrated extensive CuOH and NiOH transfer between chalcocite and heazlewoodite minerals. The statistical analysis has been able to identify mechanisms controlling recovery and selectivity. High intensity conditioning (HIC) tests in which sphalerite was separated from a complex sulfide ore gave a 5% increase in the overall Zn recovery. The PCA/ToF-SIMS statistical analysis revealed the discriminating depressant action of adherent aluminosilicate (gangue) fine particles and adsorbed ions on the surface of sphalerite grains. HIC conditioning resulted in the removal of these gangue fines improving surface collector attachment efficiency.

Jan 1, 2014

By D. H. Xiong

Low grade oxidized iron ores are usually not economic to utilize. However, the development of SLon magnetic separators and other new technologies make the process cost lower and lower. In this paper, several low-grade oxidized iron ore process flowsheets are introduced. The key procedure is that at the early stage, SLon magnetic separators are applied to discharge as more tails as possible with very low cost, only a small portion of rough concentrate going to the cleaning stage, showing the new technologies are profitable for such iron ores.

Jan 1, 2014

Taknar polymetal (Cu-Zn-Au-Ag-Pb) deposit and concentration flotation plant are located in the northeast of Iran. The flotation feed contains Chalcopyrite, sphalerite and pyrite with 4, 4 and 8 percent respectively. Cu and Zn contents are 1.26 and 3.5 present. Pyrite decreases the quality of base metal concentrates and increases the amount of sulfur compounds produced in the base metal extraction processes. Therefore, depression of pyrite is essential in the concentration of base metal sulfides by flotation. For flotation tests, 4 mixed collector systems, MIBC (20g/t), lime and tow depression systems (sodium cyanide (60g/t)-zinc sulphate and dextrin (300g/t)-zinc sulphate) were used as collector, frother, pH regulator and pyrite-sphalerite depressants in the chalcopyrite flotation stage, respectively, and SIPX, MIBC, lime and copper sulphate (as activator) were used in sphalerite flotation from first stage tailings. The results have shown that, sodium cyanide is a suitable depressant for pyrite and sphalerite in the first stage of flotation. Compared to dextrin as depressant, chalcopyrite recovery was decreased approximately 1.83%. In addition, when sodium cyanide was used as pyrite depressant, copper sulphate consumption raised approximately 90 g/t for activation of sphalerite. From Environment and HSE points of view, dextrin is natural, biodegradable, and non-toxic while cyanide is very high toxic. Keywords: sequential flotation, Cu-Zn massive sulphide, pyrite depressant, dextrin, cyanide

Sep 1, 2012

By Y. F. Hou

This paper reports the results of the study of the influences of concentration and modulus of sodium potassium silicate solution (Na-K activator) and curing mode on the phase composition, mi-crostructure and strength development in the geopolymers prepared using Class F fly ash. X-ray dif-fraction (XRD), Fourier transform infrared spectroscopy (FTIR) and MAS NMR are utilized in this study. It shows that the compressive strength increases while sodium potassium silicate solution modulus increases, but when modulus exceeds 1.7, the compressive strength decreases, and it decreases markedly while modulus is greater than 2.0. The compressive strength improves with increase of sodium potassium silicate solution concentration. When the concentration is 36%, the compressive strength reaches the maximum. Elevated temperature can increase the strength of samples synthesized using sodium potassium silicate solution with 32% concentration and modulus 1.2. Compared to the strength of the sample cured at 50?, the strength of the samples cured at 65? and 80? are higher at 1 day and 3 days, but when cured at 80?, strength is smaller than that cured at 50? for 7 days. When temperature is too high, too long curing time will decrease the strength. Long precuring at room temperature before application of heat is beneficial for strength development, and there is about 10%~50% increase in strength of the samples cured at 1 day precuring and 2 days elevated temperature as compared to the strengths of the samples cured for 3 days at elevated temperature or cured for 28 days at room temperature. The main product of reaction in the geopolymeric material is amorphous alkali aluminosilicate gel.

Jan 1, 2014

By Yosep Han

Mechanically-induced chemical reactions between natural beach ilmenite (FeTiO3) and silicon (Si) have been examined by a combination of X-ray diffraction (XRD) and scanning electronic microscopy (SEM) analyses. The effect of various milling time on the phase transformation, crystallite size, and lattice strain of a beach sand ilmenite with silicon, and on their leaching behavior in hydrochloric acid (HCl) has been investigated. For mechanically activated FeTiO3, the crystallite size decreased and lattice strain increased monotonically with time of milling. However, the mechanochemically synthesized ilmenite with silicon showed a relatively smaller crystallite size and greater lattice strain compared with the mechanically activated ilmenite under the same milling condition. In accordance with the elapse of milling time, the intensity of both pure FeTiO3 and mechanically activated FeTiO3 gradually decreased. However, in case of the mechanochemically synthesized ilmenitereduction of FeTiO3 by silicon resulted in formation of rutile TiO2 at the milling time of 20 h and afterwards. Additional leaching experiments were carried out at an HCl/ilmenite (wt%) ratio of 20:1. The concentration of HCl was 3 M and the reaction temperature ranged from 70 to 90 oC. Mechanical activation was observed to significantly enhance the dissolution rates of both iron (Fe) and titanium (Ti) in HCl. Particularly, effects of both milling time and silicon addition on the dissolution rates of titanium and iron were significant, while those of temperature were relatively minor under the conditions investigated in this study. Keywords: mechanochemical treatment, natural beach ilmenite, silicon, leaching behavior

Sep 1, 2012

By W. M. Zeng

A mixed culture of moderately thermophilic microorganisms was enriched from Acid Mine Drainage (AMD) samples collected from several chalcopyrite mines in China,which can leach copper from chalcopyrite effectively. Its tolerance to chalcopyrite was brought up to 80 g/L after being adapted to gradually increased concentrations of chalcopyrite. The effects of several leaching variables on copper recovery in Stirred Tank Reactor had been investigated. The ore contained chalcopyrite (62.2%) and galena (25.6%) as the main sulfide minerals. The results of the tests show that it is possible, operating at 8% of pulp density to attain copper extraction of 75% in 44 days. The leaching rate of chalcopyrite tends to increase with the dissolution of total iron. Microscopic counts of microorganisms in the solution tend to be higher at low pH range. Furthermore, the analyses of leached residues indicate that the passivation of this chalcopyrite is mainly due to the formation of a mass of jarosite and anglesite (about 48.3% and 21.7% in residue respectively), other than elemental sulphur layer. The bacterial community composition was analyzed by using amplified ribosomal DNA restriction analysis (ARDRA). Two moderately thermophilic bacteria species were identified as Leptospi-rillum ferriphilum and Acidithiobacillus caldus, with different proportion in the bio-pulp, 67% and 33%, respectively.

Jan 1, 2014

By Lilong Huang, Xiang Zhao, Yuan Long, Li Shi, Guowang Zhang, Xiao Xiao

"Vertical stirred mill is expected to upgrade the iron concentrate by further size reduced efficiently. The tests for fine grinding of iron ores from Baiyun Boyu iron ore, Baogang Goup, iron contained tails of Cu-Pb-Zn ore in Wanguo ore, Xiaoshalong iron ore in Qinghai were conducted in this paper. The data of appropriate grinding fineness, optimum grinding conditions and energy consumptions obtained from the test were used to select appropriate scale of the vertical stirred mill, optimize the parameters of the grinding process and upgrade the iron concentrate of the iron ore dressing plant or design the new ore dressing plant. Based on the laboratory tests, industrial system of regrinding and magnetic separation with vertical stirred mill as the regrinding mill in micro-fine grained iron concentrate upgrading has worked out very well. The grade of Fe in iron concentrates has increased to about 65.0% (by 4.0~6.5 point percent) when the iron concentrates were reground to designed fineness and the specific energy is 5.0~7.1kWh/t. The system of regrinding and magnetic separation is proven to be eco-efficient in iron concentrate upgrading."

Jan 1, 2014

By Sanjay Chaudhuri, V. K. Kalyani, Pradeep Kumar Singh, T. Gouri Charan

"Indian coal industry is the world's third largest in terms of production and fourth largest in terms of proven coal resources. Indian coal deposits are generally of high ash content varying from 24 to 50%. The coking coal reserves of India constitute about 12% of the total coal inventory, and the coals are washed in washeries, before being used for metallurgical purposes. The processes used for washing coking coal is Jigs, Heavy medium bath and Cyclones for the sizes upto 0.5mm, while the coal fines are washed in spirals and conventional flotation cells. Extensive studies were carried out for understanding the performance of an operating conventional flotation plant. The performance studies revealed that appreciable quantity of clean coal is being lost in the tailings due to varied reasons and the required quantity and quality was not achieved. In this study, laboratory Flotation experiments were carried out to examine the cleaning characteristics of the said tailing and to determine the effective process parameters for recovery of clean coal at desired ash level ( 16-17%). Response Surface Methodology was applied to investigate the operating conditions of the Froth Flotation for modeling and optimization. Primary study reflects that there is a possibility to recover clean coal at 16-17% ash level with a yield of about 60-70% from that Flotation tailing of feed ash about 28%.INTRODUCTIONMost of the Indian coking coals are difficult in cleaning characteristics and high ash content due to its drift origin and its age of formation for more than 225 million years. Indian coking coal reserve is limited about 12% of total coal reserve. The minerals are homogeneously mixed with the coal macerals. The open cast mining practice and mechanized mining methods are being adopted to meet the increasing demands of coals resulting in generation of more coal fines and subsequently the quality is deteriorated. Indian good quality coking coal reserves of higher seams are fast depleting and hence coking coals of difficult cleaning characteristics of lower seams (LVC) are being now explored. Due to increased mechanization of coal mines to cope up the increased demand and followed by size reduction of lower seam coals in search of better liberation , the coal fines are increasing by leaps and bounds. The processes used for washing coking coal is Jigs, Heavy medium bath and Cyclones for the sizes upto 0.5mm, while the coal fines are washed in spirals and conventional flotation cells."

Jan 1, 2018

By T. V. Vijaya Kumar

Most of the iron ore washing plants set up in India consist of sizing of the ore by dry / wet screening, washing and classification by screw classifiers followed by multi-stage hydrocycloning of screw classifiers? overflow. The underflow of the hydrocyclones forms the concentrate which is used for pellets making. As the cut-point of hydrocyclones is generally at 20 microns, relatively lower diameter cyclones in a cluster with parallel feeding are used. This is found to, often, result in choking of the spigots, at times, by extraneous material as well reporting along with the slurry. It is observed to lead to sub-optimum performance of the cyclones with loss of iron values into cyclone overflow and thereafter into tailings. Analysis of data of an operating beneficiation plant (Beneficiation Plant - 1, BP - 1) of M/s Jindal South West (JSW) Steel Limited, Karnataka, India over a period of one year indicated that weight recovery of the concentrate from two-stage hydrocycloning was 45% (with respect to feed to the cyclones) and assaying 63.43% Fe, 4.43% SiO2 and 2.32% Al2O3. CSIR - National Metallurgical Laboratory - Madras Centre (NML - MC), India developed flotation process for processing screw classifier overflow with a view to improve the recovery of ultrafine iron values from it. Detailed investigations at laboratory scale flotation column and on-site pilot plant trials proved that the production of the concentrate and productivity of the plant could be enhanced by adopting reverse cationic column flotation technology. It was established that a typical screw classifier overflow analyzing 60.54% Fe, 5.95% SiO2 and 3.67% Al2O3 could be upgraded to 64.21% Fe, 2.64% SiO2 and 2.20% Al2O3 with 82.7% weight and 84.7% Fe recovery. This translates into an increase of 80% in weight recovery of the concentrate compared to what is being obtained, at present, by two-stage cycloning. It had an added advantage of reduced SiO2 in the concentrate. Thus, SiO2 in the final concentrate could be reduced to 2.64% from 4.43% by adopting column flotation. The concentrate so generated meets the stringent specifications, especially in terms of alumina in it(should be less than 2.50%) for pellets making. Later, JSW Steel Limited set up the flotation plant in BP - 1 based on the process developed by NML - MC and was commissioned in 2010. Keywords: iron ore, washing, ultra fines, alumina reduction, column flotation

Sep 1, 2012

The present study is devoted to improvement of the leaching efficiency during phosphorous removal from high phosphorous gravity-magnetic concentrate. Before leaching the concentrate has been subjected to roasting with the addition of either Ca(OH)2 or CaO. The oolitic iron ore is roasted at 900°C for one hour. This reflects in reaction between alkaline earth additive and quartz, aluminosilicates, phosphorus, and some other minor components of the gangue minerals. The application of leaching, physical separation, and wash out of salts has resulted in the decrease of phosphorus from 0.7 to 0.15 % and it is established that the major influencing factor is the concentration of acid and to a less extent duration of the leaching process. About two third of the phosphorus can be removed by roasting with 3 % CaO to hematite, coarse grinding to d50 0.3 mm, dry high intensity magnetic separation and leaching of the magnetic fraction with hydro-chloric or nitric acid.

Sep 1, 2012

By H. C. E. Regidor, M. G. Mena, H. D. Mendoza

Cyanidation leaching has always been the most widely used method of extraction of gold in the world. Its low cost and high selectivity has made it the prevalent choice for mining companies, and even for the small scale miners. The use of cyanidation in small scale mining has been an issue for the longest time, mainly due to the operation’s lack of safety measures, health care or environmental protection regulations. In pursuit of more environmentally friendly methods of extraction of gold, several alternative extraction processes have been explored, one of which is chlorination. The chlorination process is advantageous when recovering refractory gold locked in sulfides, as it simultaneously oxidizes the surrounding sulfides as well as dissolve any gold exposed to the lixiviant. This research was conducted to study and develop a safer alternative way of extraction of gold from small scale mining operations, without compromising the recovery of gold. In this study, a variation of the chlorination process has been employed for a refractory flotation concentrate wherein the majority of the gold is locked in sulfides. Hypochlorite-bearing reagents were used as the leaching reagents, and the method developed was a 2-stage leaching process in differing pH conditions. The solution pH and Eh was monitored all throughout the runs, and aliquot samples were taken at time intervals for analysis. SEM-EDS imaging was used to determine the mode of oxidation of the chlorination process, and the image obtained showed that the oxidized layer followed the shape of the particle, suggesting a diffusion controlled process. XRD analysis of the sample before and halfway through leaching further confirmed the oxidation of the sulfides. The amount of gold dissolved in the aqueous solution and in the solid residue were used as the basis for the determination of the recovery of gold. An average gold recovery of up to 84.38% was obtained using the developed method in just 7 hours of leaching. This method was then employed for a pilot-plant scale test and a gold recovery of 79.2% was obtained.

Jan 1, 2018

By Jyotirmoy Sarma

The surface-active agent, like sodium humate, in the present systems produces a very stable suspension. Saline water up to 15% is used as a flocculating agent for recovery of water from the dispersed phase containing 1% solid. The recovered water in the presence of humate at different concentrations (0.05-0.2%) and at pH 8 also produces a stable dispersed phase of iron ore fines and tailings. The beneficiation techniques adopted in the present systems can increase ~ 2-3% iron value in the concentrate of iron ore fine, however, for tailings the increase in iron value is not observed. Keywords: beneficiation, flocculation, iron ore fines, tailings, saline water, surface-active agent

Sep 1, 2012

By Q. Cui, Z. G. Song, S. S. Lin, S. Q. Li, S. S. Lu, G. B. Zheng, A. J. Ren

"Mine tailings is one of the most important bulk industrial solid wastes, but its rate of comprehensive utilization is relatively low. Efficient separation, recovery and utilization of the valuable components is one focus of the comprehensive utilization of tailings. Beneficiation recovery of the valuable minerals is the most direct comprehensive utilization method for tailings. There are generally different kinds of nonmetallic minerals contained in the nonferrous metal mine tailings, which are secondary mineral resources waiting for further developing and recovery. Comprehensive utilization test studies on fluorite in tungsten beneficiation tailings and feldspar in molybdenum beneficiation tailings have been carried out by author and good test results are achieved. Some of the technologies developed in the test study have been applied in industrial productions, which have been working well. The economic, social and environmental benefits are remarkable. Our test studies and some production practices will be summarized and current situation and existing problems of comprehensive utilization for nonferrous metal mine tailings will also be discussed. Assumption and prospect for the future study on comprehensive utilization of nonferrous metal mine tailings will be brought at last.INTRODUCTION Mine tailings is one of the most important bulk industrial solid wastes, but its rate of comprehensive utilization is relatively low. Efficient separation, recovery and utilization of the valuable components is one focus of the comprehensive utilization of tailings. Beneficiation recovery of the valuable minerals is the most direct comprehensive utilization method for tailings. There are generally different kinds of nonmetallic minerals contained in the nonferrous metal mine tailings, which are secondary mineral resources waiting for further developing and recovery. Comprehensive utilization of nonmetallic minerals of nonferrous metal mine tailings not only can improve the value of the ore but also reduce the stock of tailings, being the key to reduce emissions at source for exploitation of nonferrous mineral resources (Cai, Yang, 2000)."

Jan 1, 2018

By S. J. Dai

The cadmium and cyanide are main poisonous components in cyanide electroplating cadmium waste water of an electroplating plant in Shenyang. The content of cadmium is about 26 mg/L and the content of cyanide is about 11.782 mg/L in this waste water. The main form of cadmium and cyanide are ions which are Cd2+and CN?. Because the cadmium and cyanide exceeded the standard seriously, the waste water must be disposed before it discharges. The microbiological method of treating heavy metals in wastewater has many advantages. For example, it has a fast adsorption velocity, high processing efficiency, wide range of pH and temperature, few invest, low running cost, no the second pollution and so on. At the same time, the CN? could be degradated by some microbiology. The physical nature, the chemical nature of Bacillus mucilaginosus, the adsorbing condition and adsorbing regular of Bacillus mucilaginosus to cadmium in the wastewater are studied by using Bacillus mucilaginosus as adsorbent removing cadmium from electroplating wastewater. The experimental results show that the adsorbing rate of cadmium is over 92%, under the room temperature(about 25?), stiring revolution in adsorption being 800 r/min for 30 min, pH being 5 , the bacteria being cultured after 5d with the biomass of Bacillus mucilaginosus 40g/L (wet weight). The mechanism in biosorption process of Bacillus mucilaginosus to cadmium is analyzed and discussed by TEM , Zeta potential,and infrared spectroscopy analysis. The results showed, the chemical involving is main adsorbing form, while electrostatic attraction, ions exchange, hydrogen bonding and Van Der Waals force are concerned cooperatively. ?NH2 ?, ?C=O?, ?C=O?NH?CH2, ?CH3, ?OH are main adsorbing groups. At the same time, the floatablity of removing cyanide by Bacillus mucilaginosus is explored.

Jan 1, 2014

By Xiong Dahe

In recent years many creative technologies are applied to SLon vertical ring and pulsating high gradient magnetic separators. SLon-2500 and SLon-3000 vertical ring and pulsating high gradient magnetic separators are created towards larger scale. Through optimizing the magnetic system and lowering the electric current density, their energy consumption is obviously dropped. New magnetic matrixes are developed to raise the beneficial efficiency of valuable minerals. Special SLon vertical ring and pulsating high gradient magnetic separators are developed which can treat coarser particles of 0-5 mm. Through these technology creations, the mineral processing efficiency of SLon magnetic separators is further raised and their processing cost dropped. Therefore, they have been found wider applications. SLon-2500 applied in Essar Steel of India. In 2007, Essar Steel did a test on its Kirandul hematite ore with SLon magnetic separator and got very good results. The feed grade is 59.77%Fe, after SLon one roughing and one scavenging, the total iron concentrate grade is 65.00%Fe and iron recovery 93.86%. In 2008-2010, the company bought 10 SLon-2500 magnetic separators to treat such iron ores. In 2010 the first SLon-3000 was applied to processing ilmenite. The magnetite-ilmenite deposit is located in Pan Zhi Hua, Si Chuan Province of China. The ore processing flow sheet is: Drum low intensity magnetic separator is used to take out magnetite, and then the SLon-3000 is used to recover ilmenite for roughing. The mags of the SLon-3000 are further cleaned by flotation. The SLon-3000 average operational results are: feed grade 9.52%TiO2, mags grade 17.43%TiO2, mags mass ratio 41.01%, TiO2 recovery 75.09%, non-mags grade 4.02% TiO2, non-mags mass ratio 58.99%. SLon magnetic separators Applied to treat 0-5mm limonite: The feed of SLon magnetic separator is usually 0-2 mm which needs to be ground by ball mill. As many Chinese iron ores are poor grades, if we can throw part of tails before grinding, the grinding cost will be greatly reduced. In 2010, a SLon-1500 and a SLon-2000 were specially built to treat 0-5 mm limonite. The feed grade is 26.51%Fe, mags grade 53.20%Fe, iron recovery 64.26, and tails grade 13.66% Fe. SLon-2500 applied to purify quartz. In 2009, a SLon-2500 magnetic separator was applied to purify quartz in Shan Xi province. Its feed is 0-1mm quartz which contains 0.15%-0.25%Fe2O3, the designed non-mags grade need to be less 0.08% Fe2O3. The production results of SLon-2500 non-mags are 0.05-0.06% Fe2O3, much better than the designed data. SLon applied in Si Jia Ying Iron Mine to recover hematite. Si Jia Ying is a big oxidized iron mine located in He Bei Province of China. In 2005-2010, a plant annually treating 10 million tons of oxidized iron ore was built in which 39 SLon magnetic separators are applied. The total flow sheet results are: Feed grade 30.44%Fe, iron concentrate grade 66%Fe, iron recovery 80%Fe, tails grade 9.65Fe%. SLon applied to recover specularite. Li Lou Iron Mine in An Hui Province of China built a plant annually processing 5 million tons of iron ore in 2010-2011. 25 SLon-2000 magnetic separators are applied to recover specularite. The total flow sheet results are: Feed grade 31.65%Fe, iron concentrate grade 65%Fe, iron recovery 80%Fe, tails grade 10.37%Fe. SLon applied in Da Hong Shan Iron Mine. Da Hong Shan Iron Mine is located in Yun Nan province of China. It treats 4.5 million tons of oxidized iron ore annually. 15 SLon-2000 magnetic separators are applied to recover hematite. The total flow sheet results are: Feed grade 35.61%Fe, iron concentrate grade 64.95%Fe, iron recovery 74.08%Fe, tails grade 15.55%. Keywords: SLon magnetic separator, iron ore, ilmenite, quartz, beneficiation

Sep 1, 2012

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 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 N. Syna

The selection and preparation of activated carbon suitable for specific application can often involve exhaustive adsorbent preparation and testing. This work examined an emerging technique based on modelling the correlation of observed adsorption capacity to the carbon characteristics as a means of decoupling the roles of carbon textural and surface chemical properties. The insights to these specific roles are then used in tailor-making adsorbents and in establishing the optimal carbon properties for specific application. In this study, a series of activated carbons prepared from bagasse by physical and chemical techniques and commercially available carbons were used in developing the models. These carbons were tested for the adsorption of thiourea-gold (I) chloride complexes. Thiourea is an important alternative gold lixiviant with the potential to address current ecological and safety concerns in the extraction of gold. A four-component model, which correlated the adsorption gold capacity to carbon textural and surface chemical properties, was proposed. The model fit was assessed using multi-linear regression and a partial F-test. This was followed by goodness of fit test achieved through r2, adjusted?r2 and mean square error (MSE) values. The results suggest the adsorption of the gold-thiourea complex is strongly influenced by the internal surface area and pH of the carbon. Tailor-made activated carbon from bagasse showed adsorption gold capacities of up to 198 mgAu/g adsorbent, demonstrating the potential of bagasse as a precursor for gold adsorbents and of this empirical modelling approach in developing adsorbents for metal recovery.

Jan 1, 2014