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By D. J. Borrow, K. van Netten

"A fine coal tailings feed was selectively agglomerated using a concentrated water in oil emulsion binder consisting of 95% aqueous phase and 5% organic phase. The purpose of the study was to investigate a continuous system in plug flow, providing a rapid beneficiation technique with high selectivity and recovery. The development of the novel binder was undertaken in previous work in a batch system consisting of a high-speed blender. In this previous work, it was found that agglomeration could be achieved in 3 s, providing the binder was pre-dispersed. Furthermore, it was found that, depending on the feed, only ~1 wt% of oil was required to achieve agglomeration, some 10 times less than required in traditional oil agglomeration. In a more recent study, the technique was adapted into a continuous process. Due to the rapid speed of the process using the emulsion binder it was found that a simple flow constriction within a 1 inch pipe was sufficient to achieve the selective agglomeration observed in the batch system. In this previous study, a coal feed consisting of a flotation product was agglomerated at a superficial slurry velocity of 1.3 m/s using a partially closed ball valve as the flow constriction. In the current study, a feed consisting of fine coal tailings with an ash content of 50.1% was used to establish the influence of superficial slurry velocity on the agglomeration process. The superficial slurry velocity was varied between 1.3- 4.2 m/s, while maintaining a constant pressure drop of 100 kPa across the flow constriction. The flow constriction consisted of a partially closed ball valve. It was found that increasing the superficial slurry velocity across the flow constriction reduced the amount of organic liquid required to achieve agglomeration. Under the optimum conditions, a combustible recovery of 80.4% was achieved at a product ash content of 9.6%. This work demonstrates a valuable product can be rapidly produced from tailings material using the novel emulsion binder. INTRODUCTION A significant opportunity exists to recover fine coal from material that is currently classified as waste. This waste material, also called tailings, is currently considered not economic to process due to its high ash content, low solids concentration, and the fine size of the particles. Thus, for this opportunity to be realised, a process is required that is highly selective and has the ability to economically recover fine particles at high throughputs. The technique of oil agglomeration has previously been considered as a candidate for the recovery of fine coal, as it is highly selective and has no lower limit on the size of particle that can be recovered (Capes and Jonasson, 1989). However, the cost of the oil required as the binding agent in the process has proven to be a significant barrier to any long-term applications (Swanson, Nicol, and Bensley, 1977). Recently, however, Yoon and co-workers have developed an ultrafine coal separation process that utilizes an oil phase for the recovery of the hydrophobic coal particles and have implemented an oil recycle to greatly reduce the consumption and thus cost of the oil (Yoon et al., 2016)."

Jan 1, 2018

By P. K. N. Raghavan

Bauxite is the principal source for the production of aluminum metal which has gained tremendous importance over the years due to its versatility as a metal capable of substituting almost all of the non-ferrous metals, non metals like wood, plastics, fibre glass, etc. and even steel in many applications. 90% of the high purity alumina needed for the production of this wonder metal in the world comes from bauxite. Even though alternate methods have been developed to produce alumina from non bauxite sources, owing to the high capital and operating costs involved, Bayer process still retains the superiority among all the methods by virtue of its simplicity and favourable economics. Bauxite continues to be the perfect ore for alumina production and its remarkable utilization makes it the most important non-ferrous ore. Most of the Alumina Refineries in the world process different types of bauxite and that too from varied sources. The technology employed in the Alumina Refineries depends on the Bauxite processed, with an ultimate view to produce alumina of required quality in the most efficient manner. Bureau of Indian Standards (BIS) and Indian Bureau of Mines (IBM) had from time to time put forward bauxite specifications for metallurgical and other applications. However, these are found no fully based on alumina technology, present developments and availability of different types of bauxite in the country. The aim of this paper is to provide scheme of metallurgical grading of Indian Bauxite based on the background of alumina processing technologies and availability of various types of bauxite in the country. Efforts are made here to evaluate beneficiation techniques for central Indian Bauxite from the point of view of alumina production. Keywords: bauxite beneficiation, digestion, alumina, gibbsite, bohemite, diaspore

Sep 1, 2012

By Gaom M. W.

The Mount Isa copper concentrator started operation in 1973. Its secondary grinding circuit consisted of two 5 meters diameter ball mills in closed circuit with 505 mm cyclones. At the design throughput of 800 t/h, the 80% passing size of the circuit product (P80) was about 140 µm. The then Mount Isa Mines Limited (?MIM?) installed two autogenous grinding (?AG?) mills in 1991 to replace two stages of crushing, a rod milling stage and one primary ball milling stage. One of the AG mills was later converted to semi-autogenous grinding (?SAG?) operation by the addition of a steel grinding medium to achieve the designed plant throughput of 800 t/h. The cyclone over-flow P80of the secondary ball mill circuit was reduced to 120 µm by the increased operating power in the AG/SAG mill circuits. The two secondary balls mills had a grinding power of 5.2 MW. A mineralogical study of the milled products indicated that half of this grinding power was sufficient for adequate chalcopyrite liberation. Eliminating one of the secondary ball mills could reduce energy and operating costs by more than A$2 million dollars per year. An optimisation project team was established to achieve the predicted power saving. Grinding circuit simulations were conducted for different circuit configurations. Ball mill parameters such as ball size, ball charge and feed slurry density were optimised. Cyclone body diameter, spigot and vortex finder sizes, and cyclone types were tested. The secondary ball mill circuit was redesigned and several proposed circuits were run as trial production campaigns to determine their operability and efficiency. The plant trials confirmed that one of the secondary ball mills could be decommissioned. Significant cost savings were achieved as a result. The success of the project demonstrates optimising grinding circuits can not only deliver the plant performance, but also a much lower unit operating cost through energy and maintenance savings.

Jan 1, 2014

By B. Y. Tuo

This article presents results of studies performed to determine the feasibility of using low-grade limonite ores from Yunnan deposit. Laboratory tests and commercial trials have shown that the magnetic separation can be performed with a high high-grade concentrates. The quality of the preparation concentration meets the requirements for blast-furnace smelting. The results as a whole demonstrate the feasibility of utilizing bank limonite ore. Yunnan limonite?s magnetic separation, roasting magnetic separation and flotation experimental study shows that grade of the ore grade can been from 32.91% heighten to 58.64%, a recovery of iron is 90.87%, productive rate is 51% through orthogonal test optimization; roasting magnetic separation can obtain that the grade of iron preparation concentrate is 61.16%, recovery is 67.39%, productive rate is 36%. As far as economy and enviormental protection is concerned, strong mag-netic suggested a more appropriate process. Keywords: Limonite; Roast; Magnetic separation

Jan 1, 2014

By A-M Ahonen

The paper discusses the experiences of a fast-track curriculum designed to provide the industry with engineers capable of working in minerals processing industry. The course has been done once before and the second course has been started. Students chosen have graduated from other fields of engineering. For the first course, twelve students were chosen from 152 applicants and for the second the twelve students were chosen from 96 applicants. The basic idea of the curriculum is to alternate between theoretical studies at the university and working experience periods at industrial sites. In addition, there are several one week assignment tasks at industrial sites. The theoretical periods are six to eight weeks long and there are three of them. During the first period, the teaching concentrates on unit processes and their chemical and physical background. The theme of the second period is mineral engineering systems; flowsheet development, process dynamics, control systems etc. The last theoretical period teaches environmental issues, leadership, project work and other similar topics. Each of the theoretical periods ends with an assignment week at industrial sites. The assignments are designed to wrap up the teachings of the period. For the industrial periods, the students are given learning goals, which have been discussed and designed with their industrial mentors. They are required to find relevant literature, make experimental designs, implement those designs, present the data, and make conclusions of their results. During these periods, a weekly meeting over the Internet is compulsory. Keywords: mineral processing, flowsheet development, process dynamics, control systems, constructivism, zone of maximal development, Vygotsky

Sep 1, 2012

By Xin Tan, Changgen Li

"The floatabiliby of chelate CF-collector for zinc and lead oxide minerals was described. It found that CF-collector possesses a strong collection power for zinc and lead oxide minerals as well as excellent selectivity for the gangue minerals. A new technology of zinc and lead oxide flotation with CF reagent as a collector, lead nitrite as a activator and water glass as modifier was presented. The mechanism of interaction between reagents and minerals was discussed by means of adsorption, zeta potential, nephelometric titration, XPS and infrared spectra was investigated.CF-collector, newly developed by Beijing General Research Institute of Mining and Metallurgy (BGRIMM), is a kind of chelate collector for the flotation of oxide minerals. CF-collector mainly consists of N-nitroso-N-phenylhydroxylamine ammonium salt. The CF-collector was used for the selective flotation of scheelite in the Chinese plants.In this paper, the effects of the dosages of activator Pb(NO3)2 and depressants (sodium hexametaphosphate, polyphosphate, water glass and salified water glass) on the floatabilities of several minerals (cerussite, smithsonite, calcite, dolomite, limonite and quartz) as well as their mixtures were investigated in the presence of the CF-collector. The results show that the CF-collector is the excellent collector for selective flotation of cerussite and smithsonite. Pb(NO3)2 can selectively activate the oxides of lead and zinc resulting in a decrease of the CF-collector dosage. The sodium hexametaphosphate plus the salified water glass are the effective depressants for gangue minerals. Based on the above facts, the “CF process”, namely, used CF reagent as a collector, Pb (NO3) 2 as a activator, and sodium hexametaphosphate plus salified water glass as depressant, has been used for the flotation separation of the lead oxide mixtures or zinc oxide mixtures without disliking and heating. For the feed lead assaying 19.07%, the lead concentrate assaying 49.81% Pb at the recovery 80.69% was obtained after one step flotation. For the feed zinc assaying 12.85%, a zinc concentrate of assaying 29.56% Zn at recovery 83.87% was obtained."

Jan 1, 2003

By J. J. Cai

The status of fossil fuel and secondary resource in metallurgy industry in China were reviewed, and conversion efficiency of fossil fuel, utilization technologies of secondary energy were studied. Fossil fuel, accounting for over 90% of energy structure in metallurgy industry, took in the highest flight in China, and a great deal of which was converted to secondary energy through the equipment of blast furnace and coke oven. These secondary energy which were mostly made of blast furnace gas(BFG), coke oven gas(COG) and Lindz Donawitz gas(LDG) occupied about 30% of total secondary energy. The way enhancing fossil fuel conversion efficiency, secondary resource recovery and the secondary energy such as BFG, COG, LDG utilization promoted to save fossil fuel was discussed in this paper. And efficient use of lower caloric value fuel was studied, such as preheating combustion air and fuel, generating electricity power etc. and regeneration purposes of high-caloric fuel was also researched, for producing hydrogen, methanol or direct reduction iron etc. The using model of secondary energy at iron and steel works was presented as fuel and chemical materials. The results suggest that utilization of these energy efficiently and reasonably could help to energy saving and environment protecting.

Jan 1, 2014

In this study, selective flocculating of diaspore using anion macromolecular reagent as flocculant was tested to separate diaspore from alum-silicate minerals. Firstly, the effect of pH on settling behavior of diaspore and kaolinite dispersions has been investigated. The results show that the maximum settling speed of diaspore and kaolinite appeared re-spectively at pH7 and pH3.33 which is close to the point of zero charge (PZC) of diaspore (6.8) and kaolinite(3.5). This result is in well agreement with the double electric layer theory. Secondly, the settling behavior of diaspore and kaolinite particles in different anion flocculant solution have been researched. The results indicate that flocculant solution concentration significantly affect the selectivity and the flocculating performance of anion molecular. In high concentration solution, both diaspore and kaolinite have faster settling rate compared to blank solution. How-ever, in low concentration solution, the anion macromolecular can enhance the settling rate of diaspore remarkably but has no apparent effect on the settling rate of kaolinite. This result suggests that the tested anion flocculant is a promising reagent for de-silica of diasporic bauxite. Lastly, FTIR method was employed to probe the adsorption mechanism of flocculant on diaspore and kaolinite. The results reveal that there are anion flocculant characteristic bands on the spectra of diaspore but no obvious characteristic bands of flocculant on the FTIR spectrum of kaolinite. This result is in good correspondence with settling test.

Jan 1, 2014

By Jiajun Geand, Shuli Wang, Baodong Pan, Xueqi Cui, Guangwei Zhang, Jipeng Sun

Gravity-fed three-product dense medium cyclone(GTDMC)is usually used as the main coal washing equipment in coking coal preparation plant. It can produce three products with a low density suspension at the same time. Raw coal and dense medium are fed separately into the cyclone. Only the qualified low-density medium suspension is pumped into the cyclone while the raw coal is fed into the first-stage 1200mm cyclone axially at the top end by gravity. The 1200mm cyclone with a cylindrical form is for low-density separation. The clean coal with light density and slower-settling velocity moves directly towards the low pressure zone along the axis and is carried through the vortex-finder to the overflow. Only the heavy products pass through the "separating zones" to the wall of 1200mm cyclone and then migrate into the series-connected second-stage 850mm cyclone through the tangential outlet. The medium suspension from the first-stage cyclone is thickened and contains more magnetite coarse particles. The second-stage cyclone typically consists of a cylindrical section and conical part. These are all favorable for the second-stage cyclone to separate at a high density. Production practices show that the clean coal and the gangue rarely mixed in the middling, the lower limit of the separation is 0.2 mm, the Organic Efficiency and the Ecart probable of the first stage is 98.30% and 0.026 kg/L respectively.

Jan 1, 2014

As the high-grade copper deposits in the world become depleted, there is an increasing focus on developing lower-grade ores which contain problematic impurities such as arsenic. Indeed, many high-arsenic ore bodies remain undeveloped because of their high arsenic levels. Separation of arsenic from copper at the beneficiation stage is difficult using the current processing techniques and invariably copper concentrates produced from these ores contain high arsenic levels, sometimes so high as to make them unacceptable to copper smelters. New, sustainable approaches are needed to allow development of high-arsenic copper ores while at the same time minimizing arsenic dispersion into the biosphere. The most promising route for separating arsenic from copper at the flotation stage centers on the use of pulp potential control. In recent years CSIRO has demonstrated at laboratory scale, for a number of high-arsenic copper ores, that crude flotation separation between arsenic-bearing minerals and copper-bearing minerals can be made. The differences in specific minerals responses to changes in pulp potential and pulp pH are exploited for this separation. Such separations nominally produce a low-arsenic high-copper concentrate and a low-copper high-arsenic concentrate. The former can be smelted without penalty, while the latter requires further treatment to capture and stabilize the arsenic and to recover the residual copper. Consideration has now been given to treatment options for the high-arsenic low-copper product. A pyrometallurgical option, involving a low temperature roast to selectively fume off the arsenic and leave a high-copper calcine, coupled with an arsenic stabilization step, has been demonstrated in the laboratory, and a preliminary techno-economic evaluation shows the process to be economically favorable. These results were recently published. CSIRO has now investigated an alternate hydrometallurgical option, involving atmospheric alkaline sulphide leaching of the high-arsenic product, where the arsenic is selectively dissolved leaving a copper-rich leach residue. The leaching testwork was carried at on the same high-arsenic low-copper material used in the roasting studies, enabling a techno-economic comparison of the alternate roasting and leaching treatment options to be made. The alkaline leaching work is briefly described and the results of the process option comparison presented and discussed. Keywords: arsenic, copper, economics, enargite, ore flotation, tennantite INTRODUCTION

Sep 1, 2012

By Kaustubh Joshi, Pradip, Beena Rai, Venugopal Tammishetti

"Rapid depletion of high grade iron ores coupled with the increasing demand for the blast furnace grade iron ore in recent times has shifted the research focus on the development of appropriate technologies for the utilization of low - grade alumina rich iron ore slimes. These slimes are currently being dumped into tailing ponds owing to their high alumina content. Typical constituent minerals present in the Indian iron ore slimes are hematite, goethite, gibbsite and kaolinite. Considering the fine particle size distribution (<37 microns) in the slimes, selective dispersion-flocculation seems to be one of the most appropriate process which has been explored by us. We present our successful results on a natural iron ore slime sample obtained from one of the mines in India. We have been able to achieve a concentrate assaying >67% Fe, and <3% Al2O3 and 2.8% loss on ignition (LOI) from the slime sample assaying 60.4% Fe, 7.7% Al2O3 and 5.45% LOI with an Fe recovery of 62-69% simply by adjusting the pulp pH. We have scaled up the process to a semi batch scale as a prelude to commercialize it for the beneficiation of low grade iron ore slimes."

Jan 1, 2014

By Volker Vogt, Wolfgang Sand, Eberhard Gock

"It was discovered that the selective activity of bacteria during the extraction of raw material concentrates by means of flotation could also be achieved with extracellular polymeric substances (EPS) excreted by bacteria. EPS, which is extracted by means of centrifuging bacterial cultures, can help to significantly reduce the use of cyanides, approximately 200,000 t/a of which are used for ore dressing today.The bacterium used was Acidithiobacillus ferrooxidans. In order to identify the bandwidth of the oxidation activity, 20 bacterial strains of the strain collection of the University of Hamburg were attracted to iron(II) sulfate and pyrite under defined conditions. All strains oxidized iron(II) sulfate ten times faster than pyrite.EPS has so far been derived from four strains. In general, EPS extracts are divided into a hydrophilic and a hydrophobic fraction. The hydrophilic fraction is composed of e.g. fucose, rhamnose and glucose; fatty acids such as dodecanoic acid, hexadecanoic acid, octadecanoic acid and nonadecanoic acid were found in the hydrophobic fraction.Pure mineral phases and mineral mixtures were used for the flotation tests. As opposed to current knowledge, the results were reproducible with technical flotation machines."

Jan 1, 2003

By Y. B. Zhu

Soil reconstruction and improvement trials and vegetation experiment is carried out at Shuilong-shan acid rock waste dumps at Dexing Copper Mine in China. pH value, Cu2+, Pb2+, Zn2+, etc. concentration in acid rock drainage (ARD) is also monitored every month since 2005. The results of experiment show that: Lime and topsoil stripped from open-pit is appropriated soil improvement material. Full cover soil improvement method is suitable for flat area, contour soil improvement method and hole soil improvement method is appropriate for slope area. The optimal plant species is ligustrum lucidum Ait,Lespedeza bicolor, Paspalum notatum, Veti-veria zizanioides, Eragrostis pilos and Neyraudia reynaudian. It is the best for Arbor, shrub and grass to be arranged in pairs or groups in order to remold optimal landscape. Pilot sites, covering 3ha, is established. Vegetation coverage reaches 90% in platform area, 40% in slope area. pH value in ARD increased slightly, Cu2+, Pb2+ concentration in ARD decreased, Zn2+ concentration in ARD decreased and varied slightly.

Jan 1, 2014

By Christopher M. Rule, Martyn P. Hay

"A methodology was developed in the mid-1980’s to predict plant performance from standard laboratory flotation tests. The methodology incorporates a flotation simulation program “SUPASIM” which translates flotation performance from bench-scale tests to full-scale plant. The technique is based on a simple, empirical kinetics model, and is tailored for use by the practical metallurgist. Kelsall’s unmodified equation incorporating two rate terms describing slow and fast floating components is used as the basis of the method. The flotation behaviour of an ore is described by a set of numbers, which can be compared in the evaluation of ore types, mineralogy and operating conditions. In so doing a precise relationship is developed between metallurgical performance in terms of grade and recovery and flotation kinetics.To date the performance of more than 20 flotation plants has been predicted, encompassing copper, lead, zinc, nickel, phosphate, pyrite, graphite, cassiterite, platinum and various slags. In three cases, plants have treated more than one type of ore. The method has successfully been used to predict and design four flotation plants using data generated from bench-scale laboratory flotation testwork. All have since been commissioned, and have performed as predicted. In the last year alone it has been used to drive flowsheet development for at least seven new plants in South Africa and the Americas. It is also being used to assist in the optimisation of existing operating plants."

Jan 1, 2003

By N. Dhawan

In the last decades, High Pressure Grinding Roll (HPGR) has gained significant importance in hard rock processing due to numerous metallurgical benefits such as energy savings, particle weakening, preferential damage of coarse particles, and preferential comminution-liberation. There are a limited numbers of lab-scale HPGR units throughout the world. The laboratory-scale HPGR machine at the University of Utah is first-ever lab-scale machine designed by late Dr Klaus Schönert, the inventor of HPGR. This HPGR is constructed with two counter-rotating hardened tool steel rolls, each 200 mm in diameter and 100 mm in width. The HPGR unit is equipped with eight sensors and a robust control system, which serves as an ideal system for fundamental studies and lab-scale testing. In HPGR operation, throughput, energy and product size distribution are intricately linked to specific grinding pressure, roll gap and rolls speed. The nip angle existing during the operation determines the volume of feed material above the rolls that is pulled into rolls without slip. In this paper, scale-up factors and some of the existing models have been reviewed. A number of experiments have been carried out with limestone and a slag material. The influence of operating variables and their complex relationship has been studied.

Sep 1, 2012

By Yuexin Han

The wet preconcentration of haematite, comminuted by high-pressure grinding roller was studied, using the cylindrical ferromagnetic medium. The effects of various factors including rod diameter, rod gap and background magnetic field intensity (BMFI) on the performances of preconcentration for different size fractions and the force analysis of single mineral particles with different diameter in the separation zone were emphatically investigated. The results showed that as the rod diameter increased, the rod gap decreased, and the BMFI increased the tailings grade and the tailings yield reduced while the concentrates recovery raised that was regardless of variations in feed size distribution. For the -3.2+0.18mm size fraction preconcentration, the magnetic medium with a rod diameter of 4 mm and a rod gap of 7 mm at BMFI of 454kA/m is used to get a higher performance. For -0.18mm size fraction preconcentration, the magnetic medium with a rod diameter of 4 mm and a rod gap of 4 mm at BMFI of 263kA/m is used to get a higher performance. After the classifying preconcentration, at the optimum condition, the overall concentrate grade increases by 9.56 percentage points and the concentrate recovery is up to the 82.67% with a tailing grade of 10.68% and a tailing yield of 40.31%. The magnetic force, exerted on weekly magnetic minerals was proportional, to the specific susceptibility and square of BMFI. For the same BMFI, the magnetic capturing force on coarse particles increased, and that on fine particles decreased with the increasing of rod diameter. For the lean locked-particles, considering the gravity and viscous resistance of particles, rods with a big diameter were beneficial to the capture of coarse particles and had no influence on the capture of fine particles, while rods with a small diameter were good for the capture of fine particles and not suitable for the capture of coarse particles of lean locked-particles. Keywords: low grade haematite, high-pressure grinding roller, high intensity magnetic separation, pre-concentration

Sep 1, 2012

By J. Z. Yuan

The purity of rectorite is only about 70% after preliminary mineral processing, which has limited its application. In this research, different pulp densities, different dispersants, different dispersing methods and purification flow sheets were used to purify rectorite. The results show that it is possible to obtain high pure rectorite clay with the purity above 90% and concentrate yield between 24.9% and 29.4% by the purification process with composite dispersants, stirred mill grinding dispersion and so on. The obtained high pure rectorite can be further used in rectorite nanocomposites.

Jan 1, 2014

By F. Karakas

Water based paint formulations consist of some industrial minerals with quantities varying from 20 to 50 %. Quality of paint is directly related to these minerals used as pigment or filler in the production. Titanium dioxide is the most important and expensive pigment in paint formulations. Other minerals such as calcite and calcined kaolin are used as filler and mainly as a substitute for TiO2. Consequently, particle-particle interactions including adsorption, coating and size distribution of pigment mixture directly affects the paint quality. In the present paper, a new type of pigment mixture for possible use in architectural water based paints was developed through grinding. The effect of different types of grinding methods on physical properties of TiO2 and calcite mixture and the quality of paint produced by these mixtures have been revealed. Three different types of mills; conventional ball mill, vibratory ball mill and high-speed attritor were used for grinding of TiO2 and calcite. Viscosity, zeta potential and particle size distributions were used to characterize the pigment mixtures obtained upon grinding. The quality of paint was evaluated by standards based on both wet and dry paints such as viscosity, density, opacity and gloss. The paint produced with the pigment mixtures prepared in vibratory ball mill and high speed attritor showed improvement in physical properties particularly in the distribution and dispersion of mineral particles. Keywords: grinding, pigment, paint, TiO2, calcite

Sep 1, 2012

By S. V. Volkova, S. V. Mamonov, T. P. Dresvyakyna

"The purpose of the work is complex processing of sulphide-magnetite ores with the separation of iron into iron concentrate, copper and noble metals into copper concentrate.The work shows the research results of the material composition of the sulfide-magnetite ore in the South part of the Peschanskoye deposit. According to the research results it is found that ore contains 0.59% of copper, 66% of which is related to chalcopyrite; 39.9% of iron, 81% of which is magnetite and 3.87% is sulfur, 42% of which is associated with pyrrhotite, 65% of which is a monoclinic modification. According to the results of the mineralogical analysis, it is found that the main iron-containing mineral in the ore under study is magnetite, the content of which is 45%. In addition to magnetite, iron is found in carbonates, pyroxenes, amphiboles, chalcopyrite, pyrrhotite and pyrite. The main copper mineral in the sample is chalcopyrite; covellite, chalcosine, bornite have a subordinate value. The total content of copper minerals in the sample is about 1%. The processing technology provides the three-stage grinding of the ore to a size of 65% of the class-71 µm; a cycle of copper flotation; a cycle of pyrrhotite flotation; wet magnetic separation of flotation hosts. The following optimal parameters are established for the ore under study: the alkalinity of the slurry is 250-280 g/m3 of free calcium oxide in the liquid phase of the slurry; the duration of the main copper flotation is 20 min; the consumption of butyl potassium xanthate is 20 g/t; the consumption of the foam generator T-92 is 15 g/t; the consumption of copper sulfate for the activation of pyrrhotite is 300 g/t; the magnetic field strength is 1500 Oersteds.A complex flotation-magnetic technology for the enrichment of sulfide-magnetite ore has been developed in the laboratory in order to produce a copper concentrate containing 21.6% of copper with 91.7% extraction and an iron concentrate with 66.5% of iron mass fraction and 1.2% of sulfur with an extraction of iron into the concentrate of 87.9%."

Jan 1, 2018

By Junwei Han, Wenhua Li, Wenqing Qin, Fen Jiao, Wei Liu, Jiaqi Xu

"A novel technology was developed to study the process of recycling copper from waste printed circuit boards (WPCBs), which are the main source of metal production in the next decades. The chemical compositions of the WPCBs were investigated. The results indicated that the PCB powder was mainly composed of copper (38.5 wt.%), iron, aluminum, and non-metallic materials. Copper is mainly in the form of Cu and is the most valuable metal for the recycle of WPCBs. The concentrated WPCBs powder, obtained by the mechanical process, were pressed as the anode, which was directly electrolyzed to produce copper. The effects of H2SO4 concentration, Cu2+ concentration, current density, pole pitch, and liquid-to-solid ratio on the voltage, current efficiency, and copper extraction were investigated. The results indicated that the optimum conditions were liquid-to-solid ratio of 30 mL/g, current density of 571 A/m2, sulfuric acid concentration of 180 g/L, 50 g/L of copper ion, polar distance of 3 cm. Under the conditions, a desired current efficiency could be achieved. Meanwhile, about 95.62% Cu was recovered from the WPCBs. The experimental studies also revealed that the purity of copper obtained at the highest current efficiency was higher to 99.98%. Produced copper sheet were characterized by X-ray diffraction (XRD). XRD analysis indicated that the copper was the main phase. INTRODUCTION With the rapid development of electronic industry, more and more waste electronic and electrical equipments (WEEE) are generated every year (Fogarasi et al., 2012; Liang et al., 2013). The production of printed circuit boards (PCBs) is the base of electronic industry, because it is the essential part of all electrical and electronic equipments (Schlummer et al., 2007). As a result, a considerable amount of waste PCBs containing plenty of heavy metals have to be treated. In general, PCBs contain about 28% metals that are abundant non-ferrous metals such as Cu, Pb, and Sn. Printed circuit boards can be considered as a secondary resource for recycling rather than wasting. The contents of gold and silver respectively reach 80 g/t and 3300 g/t, which are much higher than that of primary ores. Copper is the main metal of PCB and its content is as high as 26.8% ( Zhang et al., 2009)."

Jan 1, 2018