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By Erico Tabosa, Kym Runge, Peter Holtham

"The distribution of turbulence in an industrial scale mechanical flotation cell and its effect on flotation kinetics was studied using a fully instrumented 3m³ cell. The cell was operated at a copper concentrator in Australia with different combinations of airflow rates, impeller speeds and sizes and cell aspect ratio providing a wide range of hydrodynamic conditions. An analysis of the overall flotation cell performance showed that the overall copper recoveries were very similar for the conditions tested. However, by decoupling pulp effects from froth effects it was possible to evaluate whether the changes made affected the pulp zone and/or froth zone responses. The analysis showed that the overall recovery has the potential to be up to 7% higher, if not limited by froth recovery. The cell hydrodynamics were characterised by the overall energy dissipation rate and, to understand the distribution of turbulence within the cell, localised measurements were made using a piezoelectric vibration sensor. By comparing the metallurgical performance of the cell with the different hydrodynamic conditions it was found that the collection zone flotation rate constant was not directly related to overall energy dissipation, as is commonly observed at laboratory scale, where energy is usually only changed by varying impeller speed. In this study, energy dissipation rate was varied using not only impeller speed, but also the size of the impeller and the cell aspect ratio. In these circumstances, the best correlation was found to be between the collection zone flotation rate constant and the distribution of turbulence, i.e. the size of the turbulent zone."

Jan 1, 2014

By F. N. Shi

Ore breakage characterization plays an essential role in the design and optimization of comminution circuits. Recently, the JKMRC comminution research team has developed a Rotary Breakage Tester (JKRBT). The JKRBT uses a rotor-stator impacting system, in which particles gain a con-trolled kinetic energy and are impacted against the stator, causing particle breakage. The first unit of industrialised JKRBT was installed at the Anglo Research in South Africa in March 2007, and five more JKRBTs are currently being fabricated for some of the world?s major mining companies. In addition to the JKRBT, an improved breakage model has been developed at the JKMRC, which more accurately describes the effect of specific energy, particle size and incremental breakage caused by repetitive impacts. The validation outcomes show that the JKRBT, together with the new breakage model, generate statistically similar breakage parameters to the traditional drop weight tester (DWT), but with significant advantages over its predecessor. The limitations of the DWT, specifically its lack of precision of the energy input, the lengthy time required to run individual tests and the challenges en-countered in testing small particles, have all been overcome by the JKRBT. The recent developments in the JKRBT and the new breakage model offer several prospective applications. These developments have the potential to revolutionize the ore breakage characterization in the years to come.

Jan 1, 2014

By Y. X. Yang

Porous silica was obtained by acid leaching of chrysotile. The porous silica had been characterized by chemical analysis, powder X-ray diffraction (XRD), Fourier transform infrared spectros-copy (FT-IR), and N2 adsorption-desorption techniques. It is shown in this study that the porous silica retains the nanofibrous morphology of the original chrysotile, and produces a high specific surface area (SBET) of 391. 8 m2/g and total pore volume of 1. 05 mL/g. The increase in SBET and the total pore volume of the porous silica reflect the formation of micropores of 1.2~1.5nm and meso-pores of 3.2~3.8nm in diameter inside the porous structure. The hysteresis loop of N2 adsorption-desorption curve indicates mainly slit-shaped pores. The porous silica is amorphous, but its structure is regular to some extent. The structural unit of silica from chrysotile is a SiO4 tetrahedron and six-member silicon-oxygen rings with the tetrahedral positioned alternately up and down in the six-member rings.

Jan 1, 2014

By N. Vasumathi

Most of the Iron ore washing plants set up in India in the earlier days consist of sizing of the ore by dry / wet screening, washing and classification by screw classifiers. In this classical approach, iron values were lost in the form of fines and ultrafine into the tailing ponds as they had little commercial value in those days and accumulated in huge quantities over the years. As the high grade deposits are getting exhausted and the demand for high grade finer material for pellet making is ever increasing, focus is shifting towards recovering the values from the erstwhile tailing ponds by column flotation. This is also supposed to mitigate to a certain extent the environmental problems caused by the ever expanding and unmanageable tailing dams. A case study is presented wherein a composite sample is prepared from samples drawn systematically from multi - locations in a sprawling tailing dam. Laboratory scale column flotation tests on this composite tailings sample, basically originating from two operating iron ore beneficiation plants of JSW Steel Ltd., one of the leading producers of steel in India are found to be encouraging. Desliming followed by reverse and cationic flotation tests using flotation column resulted in the concentrate of 61.88% Fe, 4.81% SiO2, 2.52% Al2O3 and 3.30% loss on ignition (LOI) from the tailings analyzing 57.86% Fe, 7.10% SiO2, 3.52% Al2O3 and 6.14% LOI with 52% weight recovery. The causes for the quality improvement could be attributed to desliming of un-liberated ultra fines of kaoline and hydrated iron oxides and their further reduction by efficient flotation process. The process and the cationic collector developed for this purpose are adopted in the new flotation plant created to treat these tailings. Keywords: iron ore, washing, ultra fines, tailings pond, column flotation

Sep 1, 2012

By I. S. M. K. Ilankoon

In heap leaching the transport of the acid from the drippers to the surface of the ore particles is a major factor in the overall performance of a heap. This flow behavior is complex as the flow is unsaturated and occurs along a tortuous set of inter-particle channels and connections. Previous modeling of this system has used equations from oil and ground water flow to model these systems, but the applicability of these models with the larger particles found in typical heaps is suspect as these systems are not necessarily capillary dominated. In particular, as the characteristic particle size goes from below to above a few centimeters, the flow changes from capillary to gravity dominated. This means that typical heap leaching heaps cover this interesting, but complex, transitional fluid flow regime. In this paper a set of experimental studies of this flow, including PEPT (positron emission particle tracking) based tracer experiments, highly accurate liquid holdup measurements and axial dispersion experiments using salt tracers will be presented. In this study, flow through mono-dispersed particle beds was carried out. In particular, the hysteresis in the liquid holdup as the liquid flow rate into the particle bed is varied is investigated, since this hysteresis means that the relationship between flow rate and holdup is history dependent, an effect not included in models currently used to describe fluid flow in heaps. A theoretical model that describes this hysteresis will also be presented. Keywords: heap leaching, hydrometallurgy, modeling

Sep 1, 2012

By T. Badrujaman

In September 2005, after 30 years experiencing in operating an ESF using a falling water film shell cooling system, Antam entered the new era in operating an ESF, after completely modernized its ESF No. 2 from a falling water film shell cooling system to a copper cooling system. Further, in the beginning of 2007, Ferronickel plant No. 3, where its ESF also uses copper coolers, was successfully commissioned. By operating an ESF using a copper cooling technology, Antam has to face some challenges to establish the operation stability. Besides that, the chances to maximize the furnace efficiency are greatly opened. The shielded-arc mode of electrode tip is selected to operate an ESF under relatively high furnace power to produce metal having tap temperature below 1500? and slag having tap temperature below 1600?. It leads to electric current unbalance. Further, operating an ESF using a copper cooler system under high voltage as consequence of the furnace power raise increases metal and slag tap temperature. This condition damages furnace integrity fast. Besides that, relatively high metal temperature increases its pressure during metal tapping. It leads to failure in closing the metal tap hole. The main different ways in operating an ESF using a falling water film shell cooling system and a copper cooling system lie in the electrode tip mode, the water specification used for cooler, metal tap block maintenance and allowed metal & slag level in furnace. Since a copper cooler system allows an ESF to be operated by consuming nickel ore having ratio Fe / Ni up to eight and producing slag having relatively high Fe content in slag, an undesirable silicon reversion phenomenon becomes an obstacle in reaching the operation stability. A copper cooler technology lets Antam to take a chance to increase its capacity. Modernizing the ESF No.2 had increased its furnace power from 17 MWh to 25 MWh. Meanwhile the ESF No. 3 can be operated up to 42 MWh. This technology allows an ESF to be operated under relatively high furnace power above 25 MWh safely as well as prolong the campaign life of ESF brick. Further, lowering ESF power consumption, extending the limitation of ratio S/M in nickel ore consumed and adjusting Ni grade in ferronickel product can be gained by applying this technology.

Jan 1, 2014

By B. Vasanthakumar, H. Ravishankar, S. Subramanian, J. Braun

The flotation of sphalerite and galena in the presence of intra- and extra-cellular components isolated from Bacillus circulans before and after adaptation to the chosen minerals has been studied. Based on various biochemical treatments, the key biomolecule primarily responsible for the flotation of sphalerite has been identified as DNA, which functions as a bio-collector. A noteworthy finding is the considerably higher flotation recovery of sphalerite obtained in the presence of single stranded DNA (79.8%) vis-à-vis double stranded DNA (50.2%). Selective flotation tests using the soluble fraction obtained after thermolysis treatment highlight that sphalerite-adapted cells yield a higher selectivity index (S. I.) of 31.2 compared to galena-adapted (S.I. 4.3) or unadapted (S.I. 12.2) cells. During bacterial adaptation to the above chosen minerals, the quantitative and qualitative changes in the surface potential, surface morphology and cell wall components have been monitored. The prior adaptation of the bacteria to sphalerite results in the secretion of a higher amount of proteins, eDNA and phosphate, whereas adaptation to galena leads to a higher amount of polysaccharide, uronic acid and acetylated sugar, vis-à-vis the unadapted bacteria. A significant observation is that the bacteria undergo a change in morphology from rod to sphere as a strategy to resist metal toxicity during adaptation to galena. Interestingly, this phenomenon is not observed during bacterial adaptation to sphalerite. This morphological transition has been shown to involve changes in crucial cell wall components as well as changes in the levels of expression of bacterial cytoskeleton element mreB gene involved in the maintenance of the rod shape. The sequence of B.circulans mreB gene has been identified using Polymerase Chain Reaction (PCR) followed by DNA sequencing.

Jan 1, 2014

By E. V. Manlapig

"Some researchers postulate that the floatability of a particle in the streams of an industrial flotation circuit is a function of only its size and liberation properties. They do not discount the importance of reagent or surface contamination on particle floatability but assume that the reagent coverage or surface contamination of the particle surfaces is essentially uniform for particles of similar size and mineralogical properties when subjected to a particular chemical regime.In this paper, samples collected from batch tests performed on different streams of the Red Dog lead cleaning circuit have been characterised with respect to their size, mineral association and mineral surface exposure. An analysis of this data set indicates that particle recovery rate is significantly affected by mineralogical properties - in particular the degree of valuable mineral surface exposure.However, through the use of a nodal analysis technique developed by the authors, it can be concluded that particles with the same size and mineral composition do not all float with the same rate, but with a distribution of rates. The characteristics of this floatability distribution do not change during the flotation process. It is suspected that the particles within a size mineralogical class in this study have varying degrees of surface oxidation and that this results in varying particle flotation rates. Thus basing particle floatability on size and mineralogical effects, alone, in a flotation model is not always valid."

Jan 1, 2003

By Fedotov Pavel

"Today the main objective of improving the process of ore dressing is to reduce energy consumption and performance of the basic rule of auxiliary enrichment processes. One of the modern means of ore destruction with a minimum of energy consumption is the interparticle fracturing, for example in the roller press. There still remain the unsolved problems of the energy consumption determination and the particle size distribution of the crushing product .Existing methods for determining these parameters are empirical and require considerable expenses and time. The improved finite element was developed to solve these problems using finite element contact interaction of the rock. Also it was developed to clarify the stress-strain and the rock fracture energy in a layer. These elements are used to study ore destruction in the layer and allows to create a model taking into account the interaction of crushing particles surfaces. The same algorithm was developed determining crushing product particle size distribution in the layer on the base of the Bond’s theory of crushing. The presented finite element model allows to determine the quantity of strain energy and particle size distribution of crushed product during the destruction processes of the material in the roller press with fair accuracy."

Jan 1, 2014

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

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

Jan 1, 2018

By Y. P. Lu

PET/kaolin nanocomposites were prepared with melt blending and the structure of the composites was characterized through IR techniques. The results showed that there is stable chemical bonding between PET and kaolin. In addition, the dispersion condition of nanokaolin was observed by means of SEM and TEM. As a result, the thickness of the dispersed nanokaolin particles in PET matrix is mainly from 20mm to 200nm, and the nanosized particles congregate to some extent in the samples. In addition, it was found the kaolin particles almost homogeneously dispersed in the PET matrix, without preferential orientation because of the shear effect due to melt blending. Furthermore, the mechanical properties of PET/kaolin nanocomposites are dependent on the modification efficiency of nanokaolin. With the poor efficiency, the nanokaolin particles tend to aggregate at a high content and have a bad interfacial compability between nanokaolin and PET matrix, which lead to stress concentration, so the mechanical property descends. Experiments of different contents of modified nanokalin indicated that the intensity of PET/kaolin nanocomposites decreased firstly, then increased, and then decreased, with the nanokaolin content of 4 to 5 percent, the rupture stress of the composites showed a maximum value, which was higher than that of pure PET. On one hand, nanokaolin decreases the function among PET macromolecules, which will decline the mechanical properties, on the other hand, the piece structure of kaolinite improves the intensity of the nanocomposite. When the nanokaolin content is low, the former has the dominant effect on mechanical property, while the latter will play a leading role with the content increasing. But if the nanokaolin content still increases, the agglomeration and stress concentration will be obvious.

Jan 1, 2014

By Pamela Castillo, Marcia Muñoz, Rodrigo Luca, Brian Townley, Fernando López

In the present study we discuss the value of multi-element geochemistry as a tool for semi-quantitative to quantitative bulk mineral characterization in geological and geo-metallurgical modeling of porphyry copper type deposits, with an emphasis on hydrothermal alteration associations, types and intensities. In mine production of porphyry copper deposits much effort is placed on ore grade and geological modeling, applied for predictive mineral processing behavior, from blasting, grinding, leaching or flotation, down to waste disposal and environmental management. High confidence geological models are commonly based on geological mapping of drill core and surface/ underground exposures, combined with discrete mineral characterization (e.g., petrography, QEMSCAN®, spectroscopy, etc.). Unfortunately these are expensive and applied to limited numbers of samples, thus lacking sufficient representation and not suitable for geo-statistical modeling. In addition, geological mapping always presents uncertainty, based mostly on qualitative estimates. The combination of information usually provides geological models that are hard to combine with geo-metallurgical data, much less with mineral processing predictive behavior models. The advent of multi-element geochemistry, at low cost, has allowed employment of such tools massively, yet little use is given to the data, usually focused on elements of economic interest (main ore and credits) and elements of negative impact to concentrates and/or process. Geochemistry reflects the mineral composition of rocks, thus allowing characterization of lithology, alteration types and intensities, and mineralization. As examples of such applications we present generic classification techniques which were developed on various porphyry copper deposits of northern Chile, these based on multi-element geochemistry, allowing for semi-quantitative to quantitative high resolution modeling of key aspects of lithology, hydrothermal alteration and mineralization, and which may be cross-referenced to metallurgical test samples and by that, to geo-metallurgical properties of rocks and modeling. In addition, as data is quantitative and continuous, modelling of gangue can benefit from geo-statistical modeling.

Jan 1, 2018

By Tilak Raj Mankhand, Mudila Dhanunjaya Rao, Kamalesh K. Singh

"Zinc dust is used for the removal of primary impurities by cementation from the zinc sulphate electrolyte before electrowinning of zinc. However, the industrial zinc electrowinning plants has been reported that the zinc dust consumption is in large excess than the stoichiometric requirement. In the present investigation, morphology of the zinc dust has been altered by ball milling and utilized for the cementation of cadmium, which is one of the major impurity and compared the change in the rate of cementation with original zinc dust. Initially, 325 mesh size zinc dust was used for the optimization of the excess quantity of zinc dust to be used at a temperature of 50 °C. The chemical analysis of zinc dust before and after ball milling and morphology were studied by scanning electron microscopy (SEM), and the solution was characterized by Atomic Absorption Spectrophotometer. The rate of cementation increased with increase in ball milling time. The residual precipitate obtained after filtration was also characterized by X-ray diffraction analysis. Finally experiments were conducted to study the effect of temperature and kinetics of cadmium cementation using first order reaction kinetics. Based on the integral method, the calculated activation energy for the cadmium cementation with 4-hours ball milled zinc dust was found to be 3.39 KJ/mole. INTRODUCTION Primary production of zinc in the world is carried out by hydrometallurgical route. The primary impurities in the neutralized zinc sulphate solution that cause negative effect on electrowinning are copper, cadmium, cobalt, and nickel. Copper diminishes the current efficiency and cadmium contaminates the cathode zinc (Morgan, 1977) while electro winning. Nickel and cobalt lead to perforation in the zinc deposit and prevents the electro winning process (Abrasheva et al, 1984). Due to higher electro positivity of these metal impurities than zinc, they can co-deposit with cathode zinc at the time of electrolysis. In addition to that, some possible impurities (including cobalt) in the electrolysis may lower the hydrogen overvoltage, allowing deposition of hydrogen at cathode resulting in fall of current efficiency. The deposition of zinc on the cathode is possible only at higher hydrogen overvoltage which is practicable in the absence of such impurities (Raghavan et al., 1999). Cementation is one of the prominent purification technique, and in that less reactive metal can be replaced by highly reactive metal by allowing them into precipitation. Cementation of cadmium from zinc sulphate electrolyte is being done by the addition of zinc dust."

Jan 1, 2018

By Victor Avdokhin, Ivan Kovlekov

"Studies of the process of concentration of gold-containing sands and technogenic resources show that the main reason of gold losses is misbalance between size of gold particles and degree of roughness of mineral bed. This results in free circulation of small gold particles in pores with following washing off the particles from the bed by turbulent flows.We elaborated design of magnetic sluice, intended for improving efficiency of recovering fine gold by optimizing magnetic field of a magnetic system on the base of forming catching coat from magnetic mineralsThe magnetic sluice includes trough-shaped body from magnetic-conducting material. On the bottom of the trough, magnets are placed, and opposite poles of the magnets are oriented outwards. Thickness of the bottom is determined to be sufficient for locking magnetic lines of force of the magnets on each other. The magnets of rectangular plate shape are placed on the rough bottom, covering the whole surface or with spare areas; the magnets are placed across the trough with alteration of rows with the same pole orientation.Catching coat is formed of natural magnetic and weak-magnetic placer minerals in field of magnetic system of the sluice. Magnetic minerals, placing along magnetic lines of force, form rough coat of fluffy structure. Size of the magnetic particles is chosen taking into account expected size of gold particles, which are to be fixed on the rough coat or between the magnetic particles. Changing coarseness of particles of mineral bed allows to regulate selectivity of recovering heavy minerals.Forming artificial fleece from magnetic minerals of initial sand, increasing capacity of the bed and relative hydraulic proportionality of mineral particles of the bed provide for the most effective recovery of fine gold."

Jan 1, 2003

By B. Vasanthakumar

In this study, the effect of adaptation of B.subtilis to sphalerite and galena with respect to the selective flotation of sphalerite from the sphalerite-galena synthetic mixture has been examined. The changes in the surface charge of the mineral and the bacterium, cell wall components and the profiles of secreted proteins are discussed. The flotation recovery of galena increases with the increase in the adaptation cycle of B.subtilis to sphalerite and galena, while the flotation recovery of sphalerite is independent of the adaptation cycle with either mineral. From the gel electrophoresis analysis, the protein profile for the unadapted and adapted cells is found to differ distinctly and this may be attributed to varying molecular weight fractions arising from different growth conditions. Electrokinetic measurements showed shifts in the iso-electric points of not only B.subtilis but also of the chosen minerals after adaptation. Additionally, the zeta potential of B.subtilis is found to become less negative after bacterial adaptation to the chosen sulfide minerals, while it showed an increase in the magnitude of surface negative charge after various enzymatic treatments. The change in the surface morphology and cell wall components such as phosphate, uronic acid and acetylated sugars of the bacterial species during adaptation to sphalerite and galena has been assessed. Selective flotation tests on a synthetic mixture of galena and sphalerite confirm that sphalerite can be preferentially floated from galena in the presence of the insoluble fraction of lysed B.subtilis cells initially adapted to sphalerite, with a high selectivity index. Keywords: bioflotation, b.subtilis, mineral adaptation, sphalerite, galena

Sep 1, 2012

By E. Scheepers

The process under investigation is the large-scale production of phosphorus. Gravity delivers the feed, consisting of pelletised apatite, coke and silica (in the form of gravel), to a submerged arc furnace through ten, evenly distributed feed chutes ensuring constant packed bed volume. Within this packed bed, solid-gas reactions are dominant in generating the gaseous product. These reactions, as well as the packed bed itself, were the main focus in the development of a fully three-dimensional CFD model in which fluid flow and energy distribution are represented as functions of chemical reactions, heating and melting of material and heat losses. The associated complex process interactions necessitated the creation of two process-specific, user-developed models that integrates accurate, thermodynamical data with computational fluid dynamics calculations, as well as reaction kinetics. The boundary conditions are provided by industrial measurements, and the key model parameters of reaction kinetics were obtained by laboratory experiments for different feed mixtures. Thirteen temperature probes installed inside the refractory lining of the furnace especially for this project allowed parameter fitting and validation to be guided within the constraints of real measurements. Simulation results reveal a thin, dome-shaped, reductive zone where conditions are optimum for maximum phosphorus recovery, as well as evidence of a thermal reserve zone similar to an ironmaking blast furnace located above this reduction zone. When compared to actual operating data, the CFD model can successfully predict the specific power consumption, the phosphorus in the slag and gaseous product flowrate under given operating conditions. This CFD model forms part of a larger project that aims to create a Dynamic-CFD hybrid control model.

Jan 1, 2014

By Ronel du Plessis, John C. Davidtz, Jan D. Miller

Recent results from electrochemical measurements demonstrate that trithiocarbonate (TTC) collectors are more readily oxidized to their corresponding dithiolates than the dithiocarbonate/xanthate (DTC) collectors. Based on the traditional analysis of collector adsorption, trithiocarbonates might then be expected to be effective for bulk sulfide mineral flotation. Previous bench-scale flotation research had shown that TTC collectors are very effective for the flotation of copper sulfide minerals and PGM (platinum group metal) sulfide minerals. More recently, the TTC collectors were evaluated for auriferous pyrite recovery in benchscale plant scale flotation testing in the United States and in plant tests at Anglogold in South Africa. TTC collectors were also applied in bench-scale testing of a PGM ore. In each case an improved separation efficiency was realized. Fundamental studies at the University of Utah examining the effect of collector structure (functional group, -O-CS2 versus .S-CS2), specifically with respect to auriferous pyrite flotation, are in progress. The effect of collector structure was evaluated with air as well as nitrogen as the flotation gas medium. Experimental techniques utilized included electrochemically controlled contact angle measurements to evaluate mineral hydrophobicity and infrared spectroscopy to explain collector adsorption phenomena at the mineral surface.

Jan 1, 2003

By Arkady Senchenko, Andrey Vasiliev, Alexander Aksenov, Metodi Zlatev

"This paper considers the issue of treating argillaceous oxidized ores with low gold grade (around 1.0 g/t). These ores according to their gold recovery level can be treated by heap leaching and agitation cyanide leaching, but low gold grade makes this treatment uneconomic. Heap leaching of argillaceous ores requires high consumption of binding agent for pelletizing to create suitable hydro-physical properties of material, which leads to increasing process cost and makes the material treatment unprofitable. Agitation cyanide leaching of this ore requires grinding processes; these expenses would not be paid back by the amount of gold recovered. Considering the above, poor argillaceous oxidized ores are recommended to be treated according to a combined technology including fractionation of ore, heap leaching of coarse fraction and agitation leaching of argillaceous fraction. Complex approach application allows one to avoid expenses incurred for material grinding and high consumption of binding agent for pelletizing. The success of this technology implementation will firstly depend on the quality of material fractionation, therefore the section of disintegration and division of ore into different components will be the most important part of flowsheet development for gold production. When disintegrating minerals at positive temperatures both standard (mechanical disintegration - scrubbers) and innovative (hydraulic method of disintegration - HydroClean units) equipment is applicable. HydroClean units are characterized by lower energy and water consumption. In a number of cases it is required to treat frozen ores. When treating frozen material standard approaches to disintegration are not reasonable due to their low efficiency. In order to treat frozen material a two stage disintegration flowsheet with screening after each stage is recommended. The first stage is recommended to be performed in a scrubber, the second - in a HydroClean unit. This technological flowsheet will provide high and steady values for ore separation into fractions at low energy consumption for disintegration."

Jan 1, 2014

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 Arkady Senchenko

At present, there are different traditional and modern methods for ore grindability evaluation. The correct and rational approach to sampling, testing methods and mill sizing enables one to design a workable technology. This paper contains TOMS institute experience in different grinding indices determination over the last 7 years (SAG Design Test, BWi, CWi, RWi, and other). Mill sizing examples and circuits modeling for the projects in Russia and Kazakhstan are considered. Keywords: ore grindability, SAG Design Test

Sep 1, 2012