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By Shibayama A.

In this research, an investigation of a process to selectively remove arsenic (As) and antimony (Sb) contained in enargite (Cu3AsS4) and tennantite/tetrahedrite ((Cu1,Fe)12(As,Sb)4S13) copper resources by leaching and precipitation were performed. First in the leaching process, the target was to selectively leach As/Sb and reduce their contents in the ores to <0.5 wt% followed by a second process to remove As/Sb dissolved in solution for environmental control. Enargite ore contained 3.65 wt% As while tennantite/tetrahedrite ore contained 5.40 wt% As and 4.85 wt% Sb. Alkaline leaching using NaHS?NaOH media at varying experimental conditions (temperature, pulp density, time, reagent concentrations) were performed to investigate the process. As/Sb precipitation studies were also performed to control high As/Sb concentrations in leach solutions by using elemental sulphur (So). Results from leaching studies showed that over 99% of As/Sb in the impure copper ores can be removed and their contents in the final solids reduced to <0.5 wt%. It was also established that such very high leaching could be achieved at 80°C within 1?6 h and pulp densities as high as 1000 g/L. The study also revealed that leach solution containing very high As/Sb concentration ranging from 5 to 20 g/L can be used as fresh solution for leaching of fresh ores until concentrations exceeding 35 g/L when it was sent to precipitation circuit for As/Sb removal. Addition of elemental sulphur at 90°C and fast cooling to 30°C allowed over 60% As/Sb precipitation and removed as Na3AsS4 and solution with reduced As/Sb concentration to leaching circuit for continuous use. Keywords: Enargite; Tennantite/Tetrahedrite; Selective Leaching; Precipitation; Sodium hydrosulfide;

Sep 1, 2012

By D. Jamróz, A. Surowiak, T. Niedoba, P. Pieta

"The separation of coal material of three types of coals originating from three various Polish hard coal mines (types 31, 34.2 and 35, according to Polish nomenclature, which were steam coal, semi-coking coal and coking coal) into particle size fractions and then into particle density fractions was done and then the following parameters were measured for each particle size-density fraction: combustion heat, ash contents, sulfur contents, volatile parts contents, analytic moisture. In this way a 7-dimensional vector of data was created. Using methods of factor analysis the important features of coal were selected, which decide about their membership to individual types. To evaluate the appropriateness of the applied method the Bartlett’s sphericity test as well coefficient of Kaiser-Mayer-Olkin (KMO) were used. To select important factors the Kaiser criterion and Cattell’s scree test were used. The obtained results were compared with the results obtained in previous works by means of observation tunnels method. The results showed which particular features are crucial to define the type of coal what is also important to select appropriate method of its enrichment.INTRODUCTION Coal extracted from the mine is often a mixture of coals of various quality originating, for example, from various coal layers. One of the most important issues is to determine its quality, what means to verify if it fulfills certain requirements. Usually, such parameters as combustion heat, ash contents, sulfur contents, volatile parts contents and analytic moisture decide what the coal quality is (Drzymala, 2009). Such investigations are expensive and time consuming. That is why it seems to be important to determine the mutual connections and interactions between them what would make possible to reduce the amount of the necessary parameters. This issue was already investigated with successes in several works [Jamróz and Niedoba, 2013; 2014; Niedoba, 2015]. This work is another approach to this problem. Here, the investigation of possible reduction of researched parameters was done on the basis of the factor analysis. The obtained results confirm the earlier observations."

Jan 1, 2018

By B. Csoke

The Bond and the Hardgrove methods are widely used for the determination of the material?s grindability. Generally, the determination of the Bond work index of inhomogeneous materials can be carried out with high deviation using the conventional apparatuses and methods, because of the highly different grindability of components. This is more significant when the composite cement?s grindability is measured, which highly affects the design and operation of cement grinding mills. A possible solution can be the combined application of the Bond-method with the determination of the component?s weight ratio in the product and perform the Bond measurement until the steady state conditions of grindability coefficient (G) and chemical composition of the components are reached. To prove the applicability of the above mentioned idea systematic Bond and Hardgrove grindability tests were carried out of two phase composite materials. The experimental results showed that the application of the combined procedure is proven in order to have a more accurate and reliable calculation of the Bond work index of composite materials, especially when the components have significant difference in the grindability and concentration. The measurements also showed the possibilities and limits of the grindability test methods.

Sep 1, 2012

By Agnieszka Surowiak, Tomasz Niedoba

The paper presents a way of determining relations between ash content in coal, particle size and particle density by means of regression, multidimensional Morgenstern distribution functions and kernel approximation. The three-dimensional random vector (D, ?, ?), where D is a random variable describing particle size, ? - random variable describing particle density and ? - random variable describing ash content, where function ?=?(d, ?) is obtained by means of regressive function. The multidimensional Morgenstern distribution functions and kernel estimators with the use of Gauss function were applied to approximate the functions f(d, ?, ?) and f1(d, ?). This approach is a new way of multidimensional description of grained materials such as coal and it also allows to evaluate material features more properly than the classical statistical approach. The results were verified statistically.

Jan 1, 2014

By Yuexin Han, Wenbo Li, Yan Shan, Yanjun Li, Shumin Zhang

"With the accelerating pace of resource extraction, the quality of resources is decreasing, and the old tailing dams which have served for several decades have become the focus of attention. The secondary recovery of valuable metals in the tailings is an important aspect of the comprehensive utilization of tailings. The average iron content of iron tailing is 8%-12% in China. The research aimed at exploring the low-cost and efficient technical route to recycle eastern tailings of Anshan iron mining area. The purpose of the research is to scientifically find the rational conditions of magnetizing roasting and to provide an increase in recovery and quality of concentrates. The eastern tailings of Anshan mining area belong to high silicon bearing iron tailings, iron mainly exists in form of hematite-limonite with an iron grade of 10.60%, the main component of gangue is SiO2 with a grade of 76.22%. In order to reduce the influence of the tailings on the environment, fluidized magnetizing roasting and low intensity magnetic separation for the eastern tailings of Anshan mining area were carried out to improve the utilization of the tailings. The results indicated that an iron concentrate with an iron grade of 65.30% and a recovery of 85.85% could be obtained under the conditions of gas flow rate 8 m3/h, H2 concentration 50%, fluidized magnetizing roasting temperature at 600? for 20s. Phase analysis, magnetism analysis and XRD analysis on roasted materials indicated that hematite-limonite could be transformed to magnetite during the fluidized roasting, then the effective separation of iron and gangues could be made easily by the weak magnetic separation. INTRODUCTION It is universally acknowledged that the grade of iron ore in China is low, the output rate of iron ore tailings is high, usually more than 60%. At present, the comprehensive utilization rate of iron ore tailings is low in China. Generally, the iron ore tailings are stockpiled in the tailings dam. The tailing dams not only occupy a lot of land, but also takes a lot of money to construct and maintain. In addition, the noxious substances in the tailings, such as residual flotation agents and heavy metals, have a severe impact on the ecological environment. There is little doubt that tailing dams have a visual impact on the environment due to their regular geometric shape. Iron tailings can be treated as compound mineral, which is an important component of comprehensive utilization of mineral resources, and is an has been widely concerned. Lots of scholars have done a large amount of research work on a large number of iron ore tailings. Since the iron mineral crystal grain size is fine and the iron grade is low, the iron tailings have failed to achieve good selection criteria."

Jan 1, 2018

Calaverite is a gold telluride found in the Kalgoorlie region, Fiji, Cripple Creek Colorado and numerous other locations. It is known that a high pH is necessary for calaverite cyanidation, with the leach rate increasing substantially above pH 12 due to the hydroxide ion concentration. In most circumstances lime is used to achieve high pH, however lime saturates at approximately pH 12, limiting the maximum pH obtainable in a critical region for calaverite leaching. Plant observations, laboratory experiments and thermodynamic modelling show that the maxi-mum hydroxide ion concentration that can be achieved with lime (CaO) is strongly dependent on common ions. The presence of calcium, as commonly found in saline waters, substantially diminishes the maximum pH that can be obtained with lime. Conversely the presence of sulfate ions, as generated through oxidation of sulfides, substantially increases the maximum pH that can be achieved with lime. Sulfide oxidation during cyanide leaching of complex ores may generate acid and sulfate ions, making overdosing with lime at the front of the circuit, or staged addition down the leach train, important to maintaining the maximum hydroxide concentration.

Jan 1, 2014

By C. Perez

In mineral processing plants it is important to estimate rock composition, size and grindability to improve control of the grinding process. It is well known that variation in ore grindability and size distribution directly affects mills power consumption and throughput. This paper extends a general machine vision approach for on-line estimation of rock mixture composition using color information. Our proposed rock lithological recognition method requires the following steps: division of each image into sub-images, color feature extraction using the Binary Quaternion-Moment-Preserving thresholding technique (BQMP) and support vector machines (SVM) for classification. The BQMP thresholding technique splits the image in two and chooses representatives of each half using the histogram as features. The statistical parameters of the color data can be expressed using the quaternion moments into the representatives. This method can be recursively applied to the sub-images, obtaining 5x2n features in n iterations. Once the feature vector has been computed, each vector is assigned to one of three classes using a classifier. The method was tested on a database containing 20480 sub-images (64x43 pixels) of five ore types as follows: massive sulphide (MS), disseminated sulphide (DS), net textured (NT), gabbro (G), and peridotite (P). These ore types were assigned to three grindability classes: soft (MS), medium (DS and NT) and hard (G and P). The database was divided in 2 subsets: 15360 sub-images used for training and cross validation and 5120 sub-images used for test. The classification accuracy was compared with a method previously published based on a mixture of principal components analysis (PCA) for color, and wavelet texture analysis (WTA) for texture feature extraction. WTA-PCA approach reached a 76% accuracy in test while our BQMP method reached 90% of classification accuracy using only color features. Experimental results show that our proposed method yields excellent results compared to previously published results. Keywords: rock classification, lithological classification, grindability estimation

Sep 1, 2012

By William Skinner, Jonas Addai-Mensah, Keith Quast, David Robinson, Jason Connor

A review of the laboratory- and pilot plant-scale physical separation techniques for the beneficiation of nickel (Ni) laterites shows limited efficacy. To date, the only upgrade technique adopted commercially, prior to hydrometallurgical processing of Ni laterites, is the removal of a barren, coarse size fraction in the feed by classification. In the present work we investigated two low grade (~ 1%), goethite-rich Ni laterite ores’ upgrading by magnetic separation, attritioning/coarse, (lower Ni-grade) gangue rejection and flotation techniques. Low intensity (0.1T) dry magnetic separation at ambient temperature of raw samples and those pre-heated at temperatures up to 450 °C showed evidence of pay metal Co and Mn bearing asbolane and/or lithiophorite minerals pre-concentration in the magnetic fractions. Ni distribution, however, did not show any noticeable magnetic upgrade but followed the weight distribution. Other ore pre-treatment methods (e.g., desliming and sulphidisation) followed by froth flotation with anionic and cationic reagents also led to noticeable (~35%) Ni upgrade. This is due to the deportment of Ni across several gangue host mineral phases (i.e. Fe oxide/hydroxide and a range of silicate/aluminosilicate minerals). From chemical analysis, after disaggregation of ~ 1% Ni grade feed ore, coarse (-600 + 38 µm) and fine (-38 µm) fractions of ~0.6% and 1.3% Ni grades respectively, were also produced, suggesting that a significant upgrade in Ni content can be achieved by rejecting the + 38 µm fraction with the loss of <40% of the Ni. The ore mineralogy, particularly the complexity and high number of un-liberated Ni-bearing phases, greatly compromises physical separation methods for these ores, with the possible exception of screening after disaggregation of the fines inherent in the run of mine ores.

Jan 1, 2014

By G. Semenchenko

Heterotrophic microorganisms Pseudomonas aureofaciens, microscopic fungi Fusarium sp. and their combinations with some chemical substances were used for gold leaching from refractory ore and flotation concentrateof Akbakaj deposit. All biological additives raised the speed of noble metals dissolution. The best results of gold extraction from ore were in the presence of bacteria or their associations with other solvents and from flotation concentrate in the presence of fungus - 30 % of additional amount of gold. The maximum extraction of gold speed value was during the first 8 hours of process. The electronic-microscopic researches of the ore samples showed almost complete decay of pyrite and arsenopyrite under bacteria influence whereas at chemical leaching most of these minerals stayed uncrushed. The presence of microscopic fungi in flotation concentrate during leaching provided full distraction of pyrite, but some crystals of antimony and arsenopyrite were undestroyed. During cyanide leaching of flotation concentrate there were accumulation of antimony and incomplete pyrite decomposition. Keywords: gold bioleaching, bacteria, fungi, complex solution

Sep 1, 2012

By B. Q. By

TiO2 is an ideal material for catalytic technology due to its unique properties. In this paper, Sm3+ doped TiO2 photo-catalyst was developed to improve the efficiency of TiO2 and to use the natural light as irradiation source, which was made from Titanium Tetrabutoxide and Samarium Oxide with the Sol-Gel process. The Sm3+-TiO2 photocatalyst was used to degrade reactive orange 4 (RO4) in Azo Dyes. The effects of solution pH, Sm3+ concentration and catalytic time on the degradation rate of RO4 were studied. The characteristics of the catalyst were analyzed with XRD and TEM. The experimental results show that the catalyst has high activity in the degradation of RO4. The Azo bonds of RO4 are active and easily broken by oxidation. The catalytic activity of the Sm3+ doped catalyst greatly depends on the pH of solution. The catalyst has high photo-catalytic activity at both neutral and alkaline conditions. The degradation mechanism of the Sm3+ doped TiO2 photo-catalyst was also discussed.

Jan 1, 2014

By I. D. Ustinov, V. A. Arsentyev, A. O. Mezenin, A. M. Gerasimov

"The solid mineral raw materials of the sediment deposits containing the argillaceous variations such as the coal and the potash ores are the most multi-tonnage solid minerals mined and processed in the territory of the Russian Federation. Both types of the deposits have relatively simple geology aspects with large and medium-sized solids and as a rule, the most often, with the regular bedding which are characterized by the fitchery thickness and the internal structure. Such deposits are very difficult for mining and processing. The thermal modification of this of ores allows changing the physico-chemical properties of its components in such a way that their further processing - grinding, separation, transportation and storage can be carried out without the use of process water or significantly reduces its consumption. The purpose of the present study is to increase the efficiency of the mineral processing containing the layered aluminum silicate by reducing their negative impact on the basic dressing processes, the separation of suspended matters and the storage of waste. INTRODUCTION Many deposits of minerals are associated with the presence of layered silicates such as the argil, mudstones, argillaceous slate - highly hydrophilic mineral varieties which have the ability to swell in the water. This ability to self-disperse creates the great difficulties both for the extraction and the processing of such ores. Since the dressing of most minerals is associated with the use of wet processes, where in contact with water the swelling layered silicates are dispersed to a particle size of less than 50 µm, but due to their high hydrophylic property they form bonds that promote the formation of so-called structured suspensions having increased viscosity. In this case the structured suspensions make it difficult to perform the separation operations as the classification, the gravity and magnetic separation, the flotation and thickening and filtration operations."

Jan 1, 2018

By R. Marandi

The effective removal of heavy metals from aqueous wastes is among the most important issues for many industrialized countries, How ever biosorption, i.e. the uptake of heavy metals by non- living biomass, has gained increased credibility during recent years. Biosorption of Cr(VI) from aqueous solution, on pretreated and immobilized Aspergillus niger was investigated in a batch and countinuous reactors. A.niger biomass pretreated by boiling in 0.5 N NaOH solution for 15 min, exhibited higher Cr(VI) removal capacity than autoclaved biomass. The optimum adsorption pH value observed for Cr(VI) ions was 2. The Cr(VI)removal rate increased with a decrease in pH. The influence of contact time, pH, Cr(VI) concentration, biomass concentration and temperature on Cr(VI) removal were also evaluated. Biosorption of Cr(VI) on pretreated biomass followed the Freundlich and Langmuir adsorption models.In this study A.niger biomass was immobilized in Na-alginate matrix. The biomass beads packed in a column were able to remove metal ions.In this study we used two different flow rate in a column, 1.5 mL/min and 3 mL/min.The breakthrough data obtained for Cr(VI) was adequately by the Thomas and Yan models and the adsorption capacity of the biomass was found to less than the adsorption capacity obtaind in the batch study. When the beads containing biomass become saturated with metal ions, the adsorbed metals were eluted using 0.5 N NaOH solution. Therefor nearly 90% of Cr(VI) was desorbed by NaOH solution.

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 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 V. Runkana, N. K. V. Nadimpalli, S. Sahu

"IsaMill™ has been in operation in the recent past for fine grinding of low grade ores to extract non-ferrous minerals. IsaMill™, typically, consists of a series of uniformly spaced identical disks mounted on a rotating shaft which is encased in an outer shell. The mill offers high energy efficiency for fine grinding and an inherent scalability. But, it encounters certain operational challenges such as non-uniform distribution of grinding media coupled with high wear rate of the disks and solid walls of the mill at specific locations—which adversely affect the mill performance. To circumvent these operational challenges, design modification of the disks through heuristics, by introducing a reduced diameter disk (RDD) at specific locations, is a common practice in industry. But there is no systematic scientific study in this regard. In the current work, we developed a discrete element method (DEM) based model and simulated for the IsaMill™ operation to study the effect of RDD on the efficiency of the mill and wear rate of the solid walls and disks. Since the first set of disks experience the high wear rate due to the high loading of the charge, the RDD was introduced at the first two disks. The simulations were performed at different diameters of the RDDs and at different media loadings. The performance of the mill was analyzed based on the power consumption, the wear rate on disks and the distribution of media particles inside the mill. Besides, the performance variables such as mean velocity of media particles and total impact energy provided useful insights into the milling operation. It was observed that the reduction in disk diameter yields lower wear rate of the disks at the cost of decrease in power draw at a constant high media loading. Whereas, when the media loading was decreased, the amount of wear and power drawn was comparable for both the most reduced and least reduced disk diameters. Therefore, there is an optimum choice of RDD for a given mill loading to maximize the mill performance while reducing the wear rate of the disks."

Jan 1, 2018

By Y. S. Sun, P. Gao

"In this investigation, a pilot-scale suspension magnetization roasting reactor was introduced and used to enhance magnetic properties of an iron ore. Consequently, the effects of roasting temperature, reducing gas CO flow rate and fluidizing gas N2 flow rate on the magnetization roasting performance were investigated. The results indicate that the hematite and siderite are almost completely converted into magnetite by a gas mixture of 3.5 Nm3/h CO and 2 Nm3/h N2 at roasting temperature of 520 °C. Under the optimized conditions, the magnetic iron concentrate with an iron grade of 60.18% and iron recovery of 90.17% was achieved. The XRD and Fe mineral phase analyses revealed that most of the hematite and siderite were converted to magnetite, and the magnetic properties were greatly enhanced. INTRODUCTION The steel and iron industry in China has rapidly developed in recent years requiring a large quantity of iron ores. Low-grade and complex iron ores are currently the overwhelmingly dominant mineral resource for iron in China. Therefore, China depends on imported iron ore resources heavily, resulting in an increase in the production costs of iron-making and steel-making[1-3]. Using domestic resources to produce a steady supply of high-quality iron ores is an important step toward the sustainable development of the steel and iron industry[4-5]. The iron ore from Jiuquan iron and steel company is abundant and recognized as typically complex iron ore resources in China. Magnetization roasting followed by low-intensity magnetic separation has been proven as the most feasible methods to upgrade refractory iron ore[6-10]. In present research, an innovative roasting technology, namely suspension magnetization roasting, was developed and applied to recover iron from a typical refractory iron ore. Suspension magnetization roasting technique and equipment developed by Prof. Yuexin Han’s Group at Northeastern University (NEU) is an effective way for the utilization of refractory iron ore. The advent of suspension magnetization roasting will, in China and even globally, produce a significant technological revolution in the field of iron ore beneficiation. Based on the previous works, this paper mainly described experiments on the separation and recovery of iron from a complex refractory iron ore by means of suspension magnetizing roasting and low-intensity magnetic separation processes. The purpose of the research is providing a new technology for effective utilization of refractory iron ore. Process parameters that affected the separation and recovery rate of iron were conducted and optimized, and the reaction process was analyzed by XRD and Fe mineral phase analysis."

Jan 1, 2018

By Nina Panteleeva, Elena Afonina, Stanislav Titkov, Jury Buksha

"Flotation processing of water-soluble minerals (potassium ores, sedimentary salts of salt lakes) is currently the main method for production of potassium fertilizers and concentrated carnallite which is the initial product for production of metallic magnesium. Flotation of sylvite (KCl) and halite (NaCl) is carried out in the electrolyte solutions: KCl-NaCl-H2O and KCl-NaCl-MgCl2-H2O. The report presents the results of studies of the effect of concentration and the electrolyte type on the size of air bubbles in a flotation cell in comparison with the floatability of mineral constituents of potash ores. The floatability in electrolytes of various compositions has been studied: - of sylvite (KCl) by alkylamines, - of halite (NaCl) by alkylmorpholines, - of silicate-carbonate slimes contained in the ore by ethoxylated surfactants. The reagent modes (regimes) activating the flotation desliming of potash ores have been developed."

Jan 1, 2014

By Tong Guan, Guangqin Fu, Lihong Deng, Xiaotong Zhou

The raw ore contains many kinds of valuable metal elements. It is rich in valuable metal elements, such as Pb, Zn, Sb, Sn, Ag and is associated with S,Fe,As,In,Cd. A new technology which includes medium intensity magnetic separation, preferential lead flotation, zinc-sulfur bulk flotation, zinc-sulfur flotation separation, tin gravity separation and tin slime flotation was chosen to recover valuable minerals in the raw ore, and the iron concentrate, the lead concentrate, the zinc concentrate, the sulfur concentrate and the tin concentrate can be obtained. To the zinc-sulfur bulk concentrate with the grade of 7.21%Zn and 16.97%As acquired by the zinc-sulfur bulk flotation, two different flowsheets of Zn-S separation technology are chosen to study. The lab test shows that when using lime+DM as depressor, the zinc concentrate assaying 47.73%Zn with the recovery of 95.01% can be obtained and the test indexes are better than that of the flowsheet which using lime as depressor. At the same time, the Cd content is 0.65% and the In content is 0.10% in the zinc concentrate, so they all reach the smelting comprehensive recovery standards and the As content decreases to 0.23%. Finally the flotation separation of christophite and As-bearing sulfide minerals can be successfully realized.

Jan 1, 2014

By M. Abdollahy

Solvent extraction of gallium from Bayer solution of Jajarm Alumina plant was investigated us-ing Kelex100 as extractant. Taguchi experimental design method was used in order to optimize the separation factor of Ga and Al. Optimum conditions were obtained as follows: Temperatuer: 65°C, volume ratio of aqueous phase to organic phase: 3.0:1.0, process time: 60min and organic phase containing 15vol.% Kelex100, 5vol.% isodecanol in kerosene. In this conditions, 74% gallium and 0.3% aluminum was extracted and separation factor was obtained 828.63.

Jan 1, 2014

By Teja Reddy, Narasimha Mangadoddy, Mandakini Padhi

"In mineral comminution circuits, the feed to hydrocyclone consists of a heterogeneous mixture having varied degrees of liberation and sizes leading to the multi-component particle system. The presence of multicomponent particles exhibits a significant change in the classification performance parameters. In this work, a numerical study is conducted with an artificial mixture of magnetite and silica of different proportions having similar particle size distribution to understand the multicomponent interaction in a laboratory scale hydrocyclone. The heterogeneous feed is injected tangentially would attain different settling rates under the influence of centrifugal, drag and turbulent dispersion forces. In this work, Large Eddy Simulation (LES) is used to resolve the continuous phase turbulence. Modified Algebraic Slip Mixture (ASM) model using the corrected Newtonian rheology of fines to simulate multi-density and multi-size particles of the mixture in a hydrocyclone. The influence of the multi-component particles on classification performance is extracted from the simulation in terms of the performance curve, i.e. recovery to underflow, volume fraction distribution and the key forces acting on each particle in the mixture. An interaction was observed between different components during the classification process, featuring accumulation of heavier particle at wall-side pushing the lighter particles into the inner locus of zero vertical velocity (LZVV) zone. The comparison of separation factors of different size particles presented the higher probability of the magnetite of same size reporting to wall region and hence to underflow. Hence, an increased component cut-size with the increased magnetite proportion, particularly a profound effect on lighter density component’s cut-size was observed. INTRODUCTION The multicomponent existence is found in naturally occurring ores, affecting the pure metal extraction, nonetheless also affects the comminution and classification processes. Among many another classifier, hydrocyclone is a vital equipment used vastly in many industries. The main advantages over other classifiers are a static body, low operating cost and maintenance, high throughput, low floor space requirement etc. A typical hydrocyclone consists of a cylindrical section with a central tube connected to a conical section with a discharge tube. The fluid is injected tangentially into hydrocyclone causes swirling and thus generates centrifugal force within the device. The multiphase interaction inside the hydrocyclone is extremely complex and mostly explained by theories based on hypothesis. In past years, many theoretical models were proposed like a balanced orbital model (Criner, 1950), the residence time model (Reitema, 1961) etc. Though these models give an estimation of the cut-size and other performance parameters, it cannot predict the accurate performance of the actual state of operation. Among these models, the balanced orbital theory is the most adapted concept, based on the force balances of the particle in the dual vortex flow of hydrocyclone. The finer particle is subjected to the inward drag force, generated from the outer vortex flow to the air core, and drags the particle towards the overflow. The larger particle with the higher mass have enhanced centrifugal force and falls into primary vortex near wall reporting to the underflow. Generally, the forces acting on the particle include the drag force, centrifugal force, pressure gradient force, added mass force, Saffman lift force, Magnus force and basset force (Kraipech, 2005). The major forces like a drag, centrifugal, pressure gradient are the function of the particle properties like the size and the density. Hence, the existence of the multi-size and the multi-density particle will affect the separation phenomenon, with the varied forces acting on it. The understanding of the multicomponent classification effect using ores has been only explored in few studi"

Jan 1, 2018