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By M. Mezzetti, E. Anders, O. Popov, P. Hoske, H. Lieberwirth, M. Voigt

"The material breakage induced by high energy electric discharges is known in general as electric impulse technology. This technology can be used for processing solid materials, such as rocks and ores. The electric impulse technology has been around for about 60 years, originally developed and intensively investigated by Russian researchers. However, the application fields have been limited to research and laboratory scale projects. Currently, there are new attempts to transfer this technology into practical industrial applications. Practical examples include drilling of deep geothermal wells with an electric impulse driven drill-head. Traditional comminution implies high energy consumption, hence, high costs. The Electric Impulse Technology is interesting for comminution of mineral and complex ores since it could allow improved recovery and energy reduction, thus resulting in significant savings. Another advantage is the dust free processing, which contributes to make minerals processing environmentally friendly. The use of electrical comminution for processing complex ores is investigated within the ELIZE research project funded by the BMBF (project No. 033R161 A) and industrial partners. The main objective is the development of an industrial scale electrical comminution machine. The first development stages include the investigation and characterization of the electric impulse induced weakening on rocks and ores. The characterization results of the preliminary trials at the microstructural scale on granite, skarn and greisen will be presented and discussed in this article. INTRODUCTION The pioneer work in the area of electric impulse technology was conducted by Russian researchers about 60 years ago [1]. While there have been some successful attempts to transfer this technology into practical applications, such as rock processing [2], laboratory processing of mineral ores [3–5], recycling [5] and geothermal drilling [6–9], the jump into practical industrial large scale application has not been accomplished yet. The Institute of Mineral Processing Machines of the TU Bergakademie Freiberg currently leads a project which can be seen as the next logical step for the technology transfer to industrial applications, namely, the development of continuously operating complex ore processing machines based on the electric impulse technology."

Jan 1, 2018

By L. M. Sun

Baotou Baiyunerbo Mines Location in Inner Mongolia is a famous deposit of iron mineral and rare earth mineral accreting. The iron ore has very complicated ingredients and minerals composing. In the mine, there is not only magnetite ore but also hematite ore, so that it is impossible for high grade iron concentrate to adopt single wet low-intensity magnetic separation or high-intensity magnetic separation to concentrate iron mineral. Because of mixing the magnetite with hematite mineral in feed ore, recovery of iron of magnetite production system in the mineral processing plant is less than other mineral processing plants. Therefore, the research for increasing recovery of iron of the magnetite production system in the plant was undertaken. The paper presented the research for using dry magnetic separation to increase recovery of iron concentrate of the magnetite production system in the plant. It mainly includes dry magnetic separation test and wet magnetic separation and reverse flotation test. The test results indicated that dry magnetic separation is a important way to improve the feature of feed ore of the magnetite production system and to increase the recovery of iron. The recovery of iron may increase from about 70% to over 80%. The research also presented optimum operation parameters of the dry magnetic separator and the separation flowsheet. In conclusion, using dry magnetic separation to treat with feed ore of the magnetite production system in the plant to increase the recovery of iron is a feasible technique. The research present a new way for the mineral processing plant to made technology innovate to increase the recovery of iron concentrate of the plant in future.

Jan 1, 2014

By D. Gucbilmez

Three spiral concentrators having different geometries were compared in a chromite processing plant. They had different diameters, helix-cross sections and capacities. Two of the spiral concentrators were manufactured in China and one of them was manufactured in Australia. The tests were carried out in a closed circuit experimental setup by using a low grade chromite ore. The pulp densities kept the same during the operation, and the samples were taken simultaneously. The effects of the different positions of the splitters on separation and the feed rate were the parameters that were observed during the experiments. The performances of three spiral concentrators were found to be different. To clarify the effect of the particle size on the separation in spiral concentrators, the screening was applied to the feed. The samples were sieved from 75µm. The test results indicated that the separation performance decreased dramatically in very fine particles. Although fine particles caused some problems in spiral concentrators, fine grinding is required for this particular chromite ore for better liberation. A suitable method for the fine particles should be investigated for acceptable recovery.

Sep 1, 2012

By Harri J. Lehto, Marja I. Oja

"The purpose of grinding circuits is to produce a particle size distribution that has as much as possible the wanted particle size class. In practise, however, the production of the wanted size class is not at all as simple as it sounds. In the case of industrial minerals for example the end user may give very tight specifications for the particle size distribution and for the chemical composition of the product. This leads in many cases to a very demanding grinding process, if we want to reach and maintain these specifications. In other words, the required size distribution is not necessary the best possible for the chemical composition.Screen models aim to predict the size distribution and flow of the products when a feed size distribution, feed tonnage, and grade efficiency curve are known. The approach used in this study was to select the most suitable empirical model for classification. Suitability of the existing models has been evaluated and accuracy compared. The tests showed that best grade efficiency model was the Rosin-Rammler model.The performance of a screen was evaluated in order to minimize the amount of fine material in the screen overflow. The experiments were carried out using Derrick single-deck screen, first alone with recycling and then in the closed circuit with a rod mill using two different scales. The separate screen tests showed the expected behaviour of the grade efficiency curves. In the pilot tests the Leonard screen efficiencies stayed almost constant. This suggests that the screen works better in a milling circuit. However the loading of the screen turned the product of the mill coarser that helped screening. The grade efficiencies obtained from the pilot tests had the same general shape. The regression analysis of the pilot test runs did not give an acceptable correlation for the parameters. This suggests that pilot tests cannot be directly used to scale or to optimise industrial milling circuits. However they can be used to predict the trends of behaviour of an industrial circuit."

Jan 1, 2003

By C. L. Tang

Parts of the wastewater are reused directly and the rest moderately purified and reused, so the utilization rate of wastewater of the whole processing plant reaches 100 percent. At the same time, beneficiation indicators have been improved stably, and great economic and social benefits have been achieved.

Jan 1, 2014

By O. L. Kachor, A. V. Bogdanov

"In 2015 in the frames of federal special-purpose program «National system of chemical and biosafety of Russian Federation (2009-2014)» Federal State Budget Educational Institution of Higher Education ""Irkutsk National Research Technical University” (further–INRTU) performed works aimed at disposal of accumulated arsenical residues at industrial site of the former Angarsk arsenical plant (AAP) processing arsenious ores from Svirsk town in Irkutsk region. The plant in 1934-1949 produced arsenic trioxide for the defence industry. Prior to starting the works on disposal of industrial pollution focus the total amount of cinders stored on 13 ha of industrial site of AAP was 156 900 tons with 1% average arsenic content. Close to the cinders there were also remains of industrial buildings and process equipment in the amount of 6 600 m3 that contained 150 tons of arsenic. Additional source of pollution at the industrial site of AAP is contaminated soil amounted to 48 000 tons. Proven reserves of gold and silver in the cinders were 6.1 and 47 g/t respectively. In 2015 the source of arsenious pollution was detoxificated according to mineral matrix technology and stored in a special landfill with separate stocking of gold-containing cinder and other arsenious residues. This technology of waste disposal specifies extraction of valuable metals from cinder in future. The similar case is with Vershino-Darasunsky settlement in Trans-Baikal Territory where the abandoned industrial site of the former arsenic plant is located in the central part of the settlement. The concentration of arsenic and valuable components can be compared to the concentration at AAP. Since 2016 the demand for removal of such industrial pollution sources is legislated due to amendments in Federal Law No. 7-FZ on environmental protection. It results in a real possibility to remove such dangerous industrial residues deposits as the one located in Vershino-Darasunsky settlement. INTRODUCTION In the frames of federal special-purpose program «National system of chemical and biosafety of Russian Federation (2009-2014)» as well as the Irkutsk region program “Environment protection in Irkutsk region"" for 2006-2015, INRTU performed the works aiming at disposal of accumulated environmental deprivation–arsenical residues from the former Angarsk arsenic plant (further - AAP) (Figure 1) on processing of arsenopyrite ores of Svirsk town in Irkutsk regionThe plant produced arsenic trioxidein 1934-1949."

Jan 1, 2018

By Leon Lorenzen, Rodrick M. Lamya

"Leaching behaviour of nickel – copper matte in a CuSO4–H2SO4 solution during the repulping stage of a matte pressure leaching process has been studied. The base metal recovery process investigated in this study consists of a matte repulping stage prior to a series of pressure leach stages. The repulping stage is essentially an atmospheric leach stage in which the Ni-Cu matte, containing small amounts of cobalt and iron, is leached in copper spent electrolyte from the tankhouse, resulting in dissolution of the nickel with simultaneous precipitation of almost all the copper.Effects of various process parameters on the kinetics and extent of the leaching reactions, as well as on the cementation of copper from the solution have been quantified. The parameters investigated were temperature, particle size, pulp density, stirring speed, residence time, initial copper concentration and initial acid concentration.Leaching characteristics of the preleached matte during the subsequent pressure leach operation has also been studied. The effects of variations in the conditions in the repulping stage on the kinetics and degree of base metal dissolution during the pressure leach stage have been investigated. Any transformations that occur in the mineral phases of the matte during the leaching process have been studied, and a leaching mechanism proposed."

Jan 1, 2003

By Briony C. Ruse, David V. Boger, Fiona Sofra1

"The sustainability of the mining industry must be addressed through improving tailings management. The use of thickened tailings and pastes stems from a paradigm shift towards designing tailings disposal sites to suit their surrounding environment, rather than manipulating the environment to accommodate the tailings. Thickened tailings and pastes usually exhibit non-Newtonian behaviour, so a thorough understanding of the rheological characteristics of the material is required in order to determine the disposal plant operating conditions.As environmental factors translate into economic issues, minimising waste production using dry disposal methods is gaining popularity. The use of rheological information is of high importance in evaluating the spreading characteristics, the transportation and the dewatering of thickened mineral tailings. The principles outlined may be applied to many industries encompassing a wide range of waste materials. The main obstacle to the widespread implementation of dry disposal methods has been the high initial capital cost of the methods due to the dewatering step, and the high cost of pumping thick suspensions across any great distance. Proper and thorough costing of tailings disposal activities combined with an accounting approach that shows closure and post-closure care costs on a per tonne basis of tailings disposed throughout the life of the tailings facility will show that dry disposal methods are more favourable than they might seem on initial appraisal."

Jan 1, 2003

By Barda K. Mishra, Surya P. Mehrotra

"INTRODUCTIONIn a jig, which is primarily a coarse mineral concentration device, the bed of mineral particles is pulsated with a stream of water resulting in the particles of different specific gravities. It operates in a cyclic manner – the jig cycle consists of four stages, namely, inlet, expansion, exhaust and compression. In the inlet stage the bed lifts up en masse. Near the end of the lift stroke the particles at the bottom of the bed start falling resulting in the loosing of the bed which, in turn, causes its expansion or dilation. During the third and fourth stages the particle resettle through the fluid, and the bed collapses back to its original volume. The pulsation and suction are repeated to bring about stratification with respect to specific gravity across the bed height. Various parameters affecting the stratification process include amplitude and frequency of pulsation, bed thickness, rate of hutch water flow, and feed characteristics. This paper first presents a review of various jigging theories and then describes a new approach to mathematical modeling of jigging employing the discrete element method.JIG MODEL BASED ON DISCRETE ELEMENT METHOD (DEM) APPROACHThe jig models based on DEM essentially involve tracking the position of each particle incrementally, applying Newton’s law of motion and a force displacement law at the contact. The model presented here is based on a three dimensional mathematical description of solid-solid and fluid-solid interactions. In this model, the force balance on a particle is extended to account for the effect of continuously varying fluid on the particle. The total force on each particle is made up of a known external body force, fluid particle interaction force and particle-particle and/or particle-wall interaction force. The fluid-particle interactive force is primarily made of drag and buoyancy. Di Felice’s correlation is used to evaluate the drag force. Solid-solid interaction is described by treating particles as discrete elements that are indestructible but interact with each other and any other elements present, such as walls, when they make physical contacts. A pair of spring and dashpot represents a contact The contact forces are computed from the amount and the rate of overlap of the particles at the contact. The motion of the particle is due to movement of the fluid, which transmits its energy through the particle-particle contacts. A computer program incorporating both the contact and the fluid model has been developed. It takes the operating parameters such as amplitude and frequency of the pulsating fluid, pertinent data concerning particle properties and the geometry of the jig bed as inputs."

Jan 1, 2003

By J. K. Afidenyo

Microbial pretreatment of a double refractory gold ore was investigated using a white rot fungus, Coriolus versicolor (ATTC 20869) to improve gold extraction. A series of preliminary tests were conducted to determine the amenability of the ore to fungus degradation. Pulp density, temperature, pH and retention times were the process variables considered. Both a single. Stage and two-step processes were studied to establish process conditions. During the single stage process, the ore was contacted with the fungus culture (biotic) for 3weeks at 30°C and pH 10.0. For the two-step process, the first step involves ore contact with the culture medium (abiotic) at 45°C and pH 10.0 followed by fungal contact (biotic) at 30°C. Results indicated that carbonaceous matter is not degraded but passivated by the fungus; as preg-robbing activities dropped significantly from 18.1% to below 1.0%. The single stage process resulted in higher gold recovery than the two-step process Gold ex-traction by cyanidation of the pretreated ore was 78.9% for the single stage compared with 15.0% for the untreated ore. In the two-step process, only 73.3% gold extraction was achieved. Application of the two step process conditions to a high grade flotation concentrate, resulted in 93.3% gold ex-traction as against untreated concentrate of 30.5%. The results show that the microbial pretreatment process degraded sulfide sulfur, passivated carbonaceous matter and enhanced gold extraction from double refractory gold ore and concentrate.

Jan 1, 2014

By Z. G. Song

As a kind of complex physicochemical process, grinding would affect the subsequent mineral processing such as flotation considerably. In this study, the effect of wet grinding on malachite and calcite flotation using sodium oleate as collector was studied. And the mechanism of the effect of grinding was investigated. Laboratory scale grinding and flotation testing of malachite and calcite samples were performed. Different grinding media were used, including steel balls and zirconia balls. It was the aim of this work to study the effect of grinding on the pulp chemistry paying particular attention to flotation recovery. The effect of grinding media and different addition location of sodium oleate on malachite and calcite flotation was studied. The methodology used in this project involved grinding the ore with and without the addition of sodium oleate in mill, measuring the pH and metal ions produced by minerals after grinding, adding various quantities of sodium oleate and determining the copper recovery. The presence of species of products on the minerals after grinding was probed using X-ray photoelectron spectroscopy (XPS), and the metal ions produced by minerals after grinding were measured by atomic absorption spectrometry (AAS). It is showed that the mil-ling environments evaluated significantly affected the flotation of malachite and calcite. This study also discusses the effecting mechanism of grinding environment on floatability of malachite and calcite.

Jan 1, 2014

By Y. H. Wang

Micro-flotation tests of spodumene, beryl, quartz and feldspar have been carried out by using CaCl2 and FeCl3 as modifiers and a blending collector of oleic acid and hydroximic acid. CaCl2 shows efficient activation for spodumene when pH is above 11.5, and FeCl3 exhibits a markedly activation and good selectivity for spodumene in the range of pH 4 to 10. The main species of CaCl2 are CaOH+ and Ca(OH)2 when pH is above 11.5, and the main species of FeCl3?6H2O are Fe(OH)+2 and Fe(OH)3 during the pH range of 4 to 10. A selective flotation of spodumene and beryl from pegmatic ore had also been completed while using FeCl3?6H2O as activator and the blending collector. A bulk concentrate containing 1.087% BeO and 4.70% Li2O has also been obtained in the flotation of spodumene and beryl from pegmatic ore assaying 0.097% BeO and 0.45% Li2O, and the recoveries of BeO and Li2O in concentrate are 74.38% and 69.50% respectively.

Jan 1, 2014

By E. V. Bratygin, S. P. Elnikova

"In the article carrying out technique of experiments for estimation of power efficiency of process of crushing in cone crushers «in a layer». The conformity of the granulometric characteristics of the crushed products obtained as a result of the tests, the theoretical equations for the size characteristics, and the choice of the optimal equation for the prediction of the granulometric characteristics of the final products obtained by crushing ""in a layer"". Optimization of granulometric composition of power of crushers working ""in a layer"" is carried out with the purpose of reduction of the electric power consumption at reception of a product of required quality. As a result of the experiments, dependencies are obtained, the relevance and applicability of the crushing process ""in the layer"" for obtaining crushed stone of improved quality is proved. INTRODUCTION A number of equations have been proposed for calculating the breakage energy. These include equations by Kirpichev and Kick, Rittinger and Bond (Bogdanov, Olevsky, 1982). Another equation for calculating the specific breakage work in breakage by impact and in stratum was proposed by Devyatkin (Boiko, 2003). In these equations, the breakage energy is proportional to the particle size raised to some power. In the equation proposed by Devyatkin, the ore piece thickness or the feed average diameter is used. The relationship between energy and breakage can be expressed as an equation (Lynch, 1981; Tikhonov, no. 3, 2008) where k is a coefficient characterizing the energy parameter depending on the strength of the feed, l is size in microns. The Rittinger formula is obtained for n = 2, the Kirpichev-Kick formula for n = 1, the Bond formula for n = 1.5. For n = 3 or higher, the equation describes fine and ultrafine grinding. R. Hookey proposed a formula (Lynch, 1981, Tikhonov, no. 3, 2008), where the size exponent n is substituted by a size function In all of the above equations, a single value of the feed and product size is used; for example, in the Bond equation, size is defined as the particle size of the 20% oversize (P80 and F80). However, a single size value can represent multiple distributions, making that the Bond method inappropriate for determining the size (Lynch, 1981). Describing an equation for estimating the grinding energy will allow to design the electric drive and ore preparation circuit for the given breakage method."

Jan 1, 2018

By Paolo Bevilacqua, Paolo Antonini, Lorenzo De Lorenzi

"Italy is one of the major producers of ceramics in the world. Ceramic production requires large quantities of K-feldspar, which is commonly sourced from granites, alkali-granites, and “granitic” sands. These rocks contain other minerals, such as quartz, plagioclase and mafic minerals, which are undesirable for ceramic production. Due to the coarse mineral grains that constitute these rocks, a reasonable liberation is achieved at a relatively coarse grind size.This paper reports a study conducted on the separation of K-feldspar from quartz, plagioclase and biotite, from a feed of ground granite. The feasibility of the separation using a dynamic dense medium separation system has been investigated, as an alternative to the traditional flotation technique. The use of a two stages cylindrical vessel (Tri-Flo) was preferred to a conical vessel, due to the improved separation efficiency. Tests were conducted on two samples of crushed granite having size distributions of –3 +1 mm and –1 +0.5 mm.Heavy liquid analysis was performed on the two samples. As the rheological properties of the dense medium interact with the separation efficiency, the stability and viscosity of the dense medium were controlled and kept within an appropriate range; which was achieved with the addition of an artificial contaminant (clay) to the dense medium."

Jan 1, 2003

By A. C. Maffei, M. V. Lins Gonçalves

Ore concentration processes are a function of the respective particle size distribution; however, most of them do not use an efficient operational method to determine it. From a practical point of view, the surface area can be calculated for any size analysis. The physical principles for determining the size distribution in each method are different, for the results will not be compared directly. During the development of the research project of the sulfide ore flotation method using inert gas, different methods for calculating the specific surface area have been used, such as sieving, sedimentation/X-ray, laser diffraction and BET, i.e. specific techniques to determine the specific surface area of copper and gold ore concentrates. The statistical method of minimum squares was used to achieve practical correlation equations among them. Regarding these two ores, if one knows a specific surface area value using one of the methods above, one can predict the result of the others. Diminution of the reagent consumption was so controlled and it could be even decreased by using inert gas.

Jan 1, 2003

By William Skinner, Ishmael Quaicoe, Jonas Addai-Mensah, Ataollah Nosrati

To date, intractable ore specific operational challenges such as poor heap geotechnical stability, permeability and high acid consumption rates associated with low grade (~1 wt%) nickel (Ni) laterites still makes the adoption of heap leaching processing unattractive. This paper presents some highlights of drum agglomeration, column leaching and characterization studies undertaken to foster the understanding and knowledge of some of the desirable product attributes of -2 mm and -15 mm, low grade saprolitic (SAP) and goethitic (G) Ni laterite feed ores and their blends (SAP/G). For column leaching, 5-40 mm agglomerate beds were continuously irrigated with 200 g/dm3 H2SO4 solution at 8.5 dm3/m2/h rate over 100 days. Ni, Co, Fe, Al and Mn extraction rates, free acid concentration, agglomerate bed slump and structural changes were determined as a function of time. The results show that at equivalent feed masses, except -15 mm G which displayed slower, pseudo-layering based behaviour, all the feeds (single and blends) displayed coalescence controlled agglomeration behaviour at varying binder dosages. Whilst the agglomerate compressive strength of the G ore was markedly higher than that of SAP ore, those of the blends were substantially similar. At fixed column leaching conditions, the Ni/Co extractions and acid consumption were higher for SAP ore whilst the agglomerate bed slump was lower than those for G ore. The bed of agglomerates produced from -2 mm G/-15 mm SAP blend was more stable than that for the -2 mm G/-2 mm SAP blend agglomerate, the latter experiencing blockage within 24 h of acid irrigation due to agglomerates breakdown. The Ni/Co extractions and acid consumption rates obtained for agglomerates of -15 mm G/-2 mm SAP blend were lower than expected based on the ratios of the SAP and G ores within the blend composition. The findings suggest that judicious saprolitic and limonitic ores’ blending could reduce acid consumption rate, improve the agglomerate bed robustness and enhance bed percolation behaviour under prolonged acid irrigation periods during heap leaching of lateritic ores of variable mineralogy.

Jan 1, 2014

By H. Q. Peng

The study of synergistic reagents combination of mineral floatation is more and more important with the decreasing of bonanzas now. In order to determine the chemical reaction mechanism, here we present the synergistic reagents combination: amyl-xanthate, butyl-dithiophosphate and N,N-diethyldithiocarbamate ester, which dissolved by different organic solvents. The reagents were applied by an Anhui mine to float low-grade covellite as a substitute for ethyl-xanthate. One reaction products Na2HPSO3?5H2O (disodium hydrogen-thiophosphate pentahydrate) which was re-crystalized and measured by X-ray diffraction analysis. In its crystal structure, the two crystallo-graphically different Na ions are six-coordinated and are bridged by two covalent bonds with the O atoms of water molecules to give a basket unit. However, we can?t get Na2HPSO3?5 H2O by combining butyl-dithiophosphate and N,N-diethyldithiocarbamate ester under the same condition. This discovery may provides a intuitionistic evidence that in the process of reaction, the three com-pounds would cooperate with each other, but the decisive reaction may be the hydrolyzation of amyl-xanthate.

Jan 1, 2014

By V. Yu. Ivanov, A. I. Yuryev, L. S. Lesnikova, M. S. Datsiev

"The Talnakh Concentrator was put into operation in 1981 using a direct selective process to produce copper, nickel and pyrrhotite concentrates.In 2001, a novel selective-bulk-selective (SBS) technology for the concentration of massive sulfide ore was implemented, that allowed to increase the valuable components recovery into target concentrates with feedstock grinding coarser than before. In 2003-2005, the process upgrading included the differentiated processing of nickelpyrrhotite products recovered at the different concentration stages and made it possible to significantly enhance the contrast of the pentlandite and pyrrhotite flotation properties and to simultaneously increase separation of polymineral intergrowths.The next stage of the PD concentration complex development is the Project ""Talnakh Concentrator Reconstruction and Technical Upgrading"" to raise its capacity by half. The project has three Phases.• Phase 1. Pilot startup was carried out in January 2015 following the installation of new OK-100 TC flotation machines, manufactured by Outotec.• Phase 2. The introduction of a new technology developed by the Polar Division specialists launched in mid-2016. The new technology is based on maximization of iron and sulfur removal into tailings and maintenance of non-ferrous and precious metals losses at the same level.After the realization of Phase 3, the annual capacity of the Talnakh Concentrator will raise by another ~ 40% at the expense of processing cuprous and disseminated ores currently being processed by the Norilsk Concentrator.By 2023, due to upgrading of the PD production facilities the emissions to the atmosphere will reduce by 75%.Polar Division of PJSC MMC Norilsk Nickel (PD) searches for the ways to solve its environmental issues. Thus, in 2016, the Nickel Plant was shutdown and a new flowsheet was introduced at Talnakh Concentrator. It resulted in the reduction of sulfur specific amount sent to pyrometallurgical processing as a component of the concentrates.The Talnakh Concentrator was put into operation in 1981 using a direct selective process to produce copper, nickel and pyrrhotite concentrates.In 1981, its design capacity for processing of Cu-Ni ores from Oktyabrsky and Taimyrsky Mines did not exceed 3 million tons per year.In 2001, a novel selective-bulk-selective (SBS) technology for the concentration of massive sulfide ore was implemented at the Talnakh Concentrator, that allowed to increase the valuable components recovery into target concentrates with feedstock grinding coarser than before."

Jan 1, 2018

By T. J. Chen

Vanadium-beard bone coal is one of important vanadium resources in China.To extract vanadium tailings from Stone coal is produced after extracted vanadium from stone coal through the roasting, leaching and other processes. About 120-150 tons of tailings will be produced in extracting 1 ton of vanadium pentoxide. A lot of tailings that are willfully piled up have caused serious environmental pollution and wasting of resources; it is therefore necessary to realize its resource utilization. This study increases the activity of vanadium tailings by means of alkali fusion, and then uses different alkali activators to react with vanadium tailings so that geopolymer with high value added is produced. Sample of geopolymer is acquired from a mixture containing vanadium tailings, alkali activators, water and a little sodium aluminate through compression-molding process under 20MPa pressure. After cured in room temperature for three days, the maximum compressive strength of the sample can reach 36.2MPa. XRD analysis indicates quartz, the major crystal phase in vanadium tailings is decomposed,and the activity of vanadium tailings is heightened. FTIR and SEM analyses show: structural change having an important impact on the mechanical strength of geopolymer occurred during the process of vanadium tailings generating geopolymer.

Sep 1, 2012

By Ramon V. V de Araújo, Roberto B. E Trindade, Pablo R. Fica-Piras

"Lead has been reported to affect blood vessels and kidneys. It also produces adverse effects in the mental and physical development of children and nervous system of adults. It is also considered as a possible cause of cancer. Because of all these threats to the human life, the reduction of its environmental occurrence, by means of recycling, is an important additional advantage to the usual ones derived of the procedures of the secondary metallurgy: lead can be recycled several times maintaining its characteristics equivalent to the primary one.Furthermore, this way of producing the metal avoids the environmental impacts of primary lead melting. Also, as an additional advantage, it triggers the metallurgical process with a raw material in what we observe higher lead content than in the natural ores. Some of the potential sources for these purposes are: ashes, slags, electrode residues, anodic muds, spent electrolytes, solid and liquid wastes, industrial or automotive catalysts, worn-out or obsolete equipment components and/or final consumption products.About 40% of world’s lead production comes from automotive batteries, mainly composed of four parts: plastic box, electrolyte (diluted sulphuric acid), contacts and connectors of Pd-Sb and plates (PbSO4, PbO2 and PbO). The plates represent 75% of the total mass. Metallic parts can be melted at moderate temperatures and then refined. The remaining fraction, constituted by the non-metallic portions, can be recovered by hydro and electro-metallurgical routes. These routes are preferred instead of pyrometallurgical ones due to the ultimate emissions of lead particulates and sulphur dioxide.The principal constituent of the residual paste of batteries is the lead sulphate. In this process, the paste is treated in two stages: in the first, lixiviating with Na2CO3 (desulphurization of the paste), obtaining PbCO3 and Na2SO4; in the second, the lead carbonate is lixiviated with HNO3, producing Pb(NO3)2, soluble, that can be converted to metallic lead by electrolysis. The reaction of PbSO4 with Na2CO3 in aqueous solutions is fast: the global rate is limited by the diffusion of the carbonate ions inside the reaction medium."

Jan 1, 2003