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By Chen Shuwen, Yao Zhihua

In the process of thickening dewatering_the motion state of two- phase flow in a thickener has a very great influence on thickening efficiency. The investigation was made using copper mill tailings. In this investigation the authors explored the formation conditions and motion range of density current in the thickening process by model experiments, and analyzed the influence of density current on thickening efficiency. The results have shown that the formation of density current has relations with the structure parameters of a thickener and thickening process. The density current and its forming location affect thickener’s working efficiency. The author measured the motion state of two- phase flow in a 53-m dial. thickener for copper mill tailings under its operation conditions and analyzed the density distribution and motion state of two-phase flow in the thickener. The results obtained by the industry tests have shown that the motion state of two- phase flow in the thickener can be greatly improved by modification of its structure, achieving a great improvement in its thickening efficiency. It is concluded that, a thickener’s working efficiency depends on the formation and motion range of density current in it, which is of great importance to designing and establishment of thickener’s working parameters.

Jan 1, 2003

By Jochen Petersen, Harro von Blottnitz

"The landfill disposal of slags is common practice in the metallurgical industry. Chromium may be a minor constituent in many cases. It is present mostly in the form of chromites, which are considered environmentally benign and hence safe for disposal. Wastewaters from metal finishing operations are most commonly treated by reduction and precipitation of dissolved metals, including chromium, by lime addition, and subsequent landfill disposal of the resulting sludge. The metals contained in such sludges are mostly in the form of hydroxides, and as such considered environmentally stable.Thermodynamically, trivalent chromium, which is the predominant form in these waste materials, can be oxidised to the hexavalent form by atmospheric oxygen. Detailed research work on both slags and sludges has shown that a gradual emergence of hexavalent chromium can indeed be observed. The mechanism is governed by close physical contact between chromium oxide (or hydroxide) phases on the one side and calcium oxide (or hydroxide), which is present as flux in slags and residual lime in sludges, on the other. If oxygen can migrate to the points of contact, gradual formation of calcium chromate ensues.Hexavalent chromium is associated with high environmental toxicity, and hence undesirable in landfilled materials. Moisture migrating through landfill deposits can mobilise the highly soluble chromates and thus potentially transport them into natural waterways. Such gradual release from stainless steel and ferrochromium slag deposits has been demonstrated in a column experiment."

Jan 1, 2003

By Hermann Wotruba, Lars Weitkämper

"Dry coal dressing was popular during the 1950’s and 60’s in many parts of the world. The devices mainly used were air jigs and air tables.The increase in ash and moisture content of run-of-mine coals due to the wide advanced mechanisation of mining methods during and after this period led to that pneumatic devices being unable to treat run-of mine coals with the desired efficiency. Since the 1960’s almost all new coal preparation plants have been based on wet processes that are highly efficient in terms of coal recovery and their ability to handle damp and sticky run-of-mine coals. (Frankland, 1995)However, water is becoming increasingly costly and the disposal of fine products, containing most of the water, is an environmental concern. There would be significant cost savings and a lower total energy consumption if coal could be cleaned dry. Efficient dry coal treatment would be an interesting solution in desert, arid or cold areas.In Germany one dry coal dressing plant is in operation. This is the last operating dry coal dressing plant existing in Europe. The actual technical standard of dry coal dressing has been analysed during test-work and sampling in this plant (Saar Region in Germany). The process and the advantages and disadvantages are presented. The plants problems are low efficiency in the fine fraction –6 mm and the coarse fraction +30 mm and a low overall throughput as well as the lack of an automatic process control system. The separation results in the medium size fractions between +6 and -30 mm are excellent"

Jan 1, 2003

By Y. F. Guo

Among the different valences of vanadium, V (?) is insoluble in acid, V (?) and V (?) is in-soluble in water but soluble in acid. Vanadium mainly exists as V (?) in vanadium titanium-rich material obtained by reduction -milling-separation from vanadiferous titanomagnetite. Therefore, the vanadium titanium-rich material can not be used to extract vanadium by acid directly. In this paper, the vanadium leaching was studied by oxidation roasting and acid leaching. Through oxidation roasting, vanadium is transformed from the insoluble V (?) into V (?) or V (?) in order to improve the leaching of vanadium. The results show that vanadium leaching increases significantly by oxidation roasting-acid leaching. Leaching of vanadium is up to 70.18% under the optimized conditions of roasting temperature of 950 ?, roasting time of 40 min, sulfuric acid concentration of 40%, leaching time of 4h, leaching temperature of 95 ? and liquid to solid ratio of 4 : 1.

Jan 1, 2014

By H. R. Zhang

In this paper two optional production processes are presented for reasonable utilization of primary sylvinite in Qinghai province, China. The two kinds of products as chlorine-free potash fertilizers; potassium sulphate or potassium magnesium sulphate can be obtained. In the course of potassium sulphate production, using primary sylvinite from Qinghai salt lake as raw material with impurities such as sodium chloride and insoluble in primary sylvinite, it must be prepared by flotation before being converted into potassium sulphate. This final product has found wide use in tobacco industry in China. However, in some cases Chinese farmers would rather buy the fertilizer of potassium magnesium sulphate than high quality of potassium sulphate. With flotation process which is a little different from above mentioned, the potassium magnesium sulphate fertilizer may be produced by washing one of the flotation concentrate presented as picromerite, while another concentrate containing potassium chloride is treated as by-product.

Jan 1, 2014

By G. P. Karmakar, K. K. Chandan

"The drilling mud is an essential part of the drilling process, which plays a major role in keeping safe and efficient oil and gas well drilling. In the oil industry, bentonite clay dissolved in water produces the simplest type of drilling muds. Bentonite clay contains montmorillonite particles. These particles are dispersed uniformly in water and such dispersions are used in various industrial products like paints, ceramics, pesticides and drilling muds. The bentonite clay easily dissolves in water and increases the viscosity of the water, which is one of the most important properties of a drilling mud. Bentonite has the highest swelling capacity, which is responsible for building up of the viscosity of the clay-water system. The flocculation behavior of bentonite is one of the major concerns for the performance of the water-based drilling mud in the oil and gas well drilling process. The behavior of drilling mud greatly depends upon the quality and quantity of bentonite clay, as well as the additives that are used in their formulations. In this work, a comprehensive study has been carried out to find out the effect of added polyacrylamide (PAM) polymer, surfactant, pH and salt concentrations on the dispersion/ flocculation characteristics of bentonite clay-water system. It has been observed that the increase in PAM dosage reduces the residual turbidity and improves the settling rate of the bentonite particles. The flocculation rate has also been found to be better under higher pH conditions. The combined effect of salt concentration and PAM dosage improved the overall flocculation efficiency of the system.INTRODUCTIONIn the oil industry, bentonite clay dissolved in water produces simplest type of drilling muds. Bentonite clay containes montmorillonite particles. These particles are dispersed uniformly in water. Such dispersions are used in various industrial products like paints, ceramics, pesticides and drilling muds (Akther et al., 2007). The bentonite clay easily hydrates in water and increases the viscosity of the mud system (Razi et al., 2013; Meng et al., 2012). Bentonite clay in the drilling mud increases the viscosity which is one of the most important prop erties of a drilling mud. Bentonite has the highest swelling capacity, which is responsible for the building up viscosity of the clay-water system (Sonmez et al., 2013). The drilling mud is an essential part of the drilling process, which plays a major role in keeping a safe and efficient oil or gas well drilling (ASME, S. S. C., 2005). The flocculation behavior of bentonite is one of the major concerns for the performance of the water-based drilling mud in the oil or gas well drilling process. This behavior of drilling muds greatly depend upon the quality and quantity of bentonite clay, as well as the additives that are used in their formulations (Yu and Amanullah, 2005; Akther et al., 2007). Bentonite particles form aggregate under certain conditions including high temperature, and high concentration (Luckham and Rossi, 1999). If the quality of bentonite is not sufficient to accomplish intended viscosity of the muds, it is essential to add certain additives to increase the viscosity and prevent aggregation of the system (Razi et al., 2013). The anionic polymer bearing sample can build up inter-particle bonds between the polymer and clay particles. The addition of various additives like, polymers control the dispersion and enhance the viscosity of the mud by controlling the flocculation of montmorillonite particles in bentonite dispersion (Heller and Keren, 2002; Mahto and Sharma, 2004)."

Jan 1, 2018

By Alexey P. Tatarinov

Under modern economic conditions in Russia, gold heap leaching is the most effective way of investing into gold-mining industry. Gold is recoverable from small-size deposits, low-grade ores from oxidation zone, cut-off grades, and overburden rocks using heap leaching. This technology is cost-effective and allows a saleable metal to be obtained within the first year of operation. The investments for heap leaching are lower than those of for a traditional plant technology. Production cost per one gram of Au is 5-7 times lower than that of during a plant flow sheet. A seasonal development of mines can be possible. With reference to this, heap leaching resembles the technology of placer deposits development. One of the major advantages of heap leaching is the form of the product. Gold can be obtained as dissolved in a clarified PLS, which allows the further quick treatment. The amenability of ores to heap leaching depends on their mineralogical composition. Oxidized porous ores with a good access of a lixiviant to valuable particles can be treated without pre-crushing. Clayish minerals are often found in oxidized ores with free gold. In order to build ground for heap, several major methods combined with various pad materials are used. These methods have been used at many plants and are reliable. The development of heap leaching technology for gold ores for the deposits from Yakutia, Zabaikalsky region, Primorye region, Uzbekistan, Tadjikistan, and Kazakhstan began in the 70s. However, it has been commercially used only since 1990. The first heap leach plants were built and commissioned in the USSR in 1991 at Vassilkovsloye deposit (Kazakhstan) and at Maiskoye deposit in Russia in 1994. Pilot plant testing was conducted in 1996 using ores from Kuranakh ore field, deposits Phiskulturnaya-Kholodnaya and Lopukhovskoye from the Aldan region. After the first successful commissioning of heap leaching plant in Russia, this technology has been commercially applied for deposits. Every year 1-2 heap-leaching plants were commissioned. More than 30 heap-leaching plants have been commissioned both in Russia and in the former Soviet Union using technologies developed by IRGIREDMET. Keywords: cyanide leaching, heap leaching, ore, percolation, solutions, lime technology

Sep 1, 2012

By Bertil I. Pålsson, Sture V. Persson, Kent T. Tano

"Autogenous (AG) and semi-autogenous (SAG) mills often operate in an unstable state because of the difficulty to balance the rate of replenishment of large ore particles from the feed with the consumption in the charge. This has led to an increased interest in obtaining an accurate and direct measurement of mill load and the behaviour of the mill charge. A problem in attempting to measure those parameters is getting a sensor that is both robust and sensitive enough for continuous on-line measurement.Techniques that measure the force acting on the lifter when it hits the charge inside the mill have got an increased interest recently because of the ability to combine it with DEM modeling. This paper presents a method for the measurement of the apparent filling level in a pilot ball mill equipped with the Metso Continuous Charge Measurement system (CCM). In this technique a strain gauge sensor is mounted on a flat steel spring which is fitted into a recess underneath a lifter bar. In addition, a conductivity probe, the Boliden Grinding Measurement System (GMS), is mounted in another lifter bar with the purpose of comparing the two measurements. To visualise the behaviour of the charge a 2D DEM modelling technique is used with Metso HFS software.The pilot mill is a grate-discharge mill, equipped with 12 rubber lifters of square size 0.1 m, face angle 45 degrees. Steel balls in the size range 10-30 mm and density 8000 kg/m3, are used in the experiments. Test material is a hematite pellet feed, d50 around 45um, chosen to get stable grinding conditions with respect to feed size variations.The experiment is meant as a first test of the equipment’s performance, and to study how the sensors respond to changes in some operating variables. To get an understanding of, and distinguish between correlation and causality, experiments are performed according to a full factorial design with two levels, and in addition two replicates of the experiments at a center-point in the charge level setting."

Jan 1, 2003

Froth flotation is an industrial process commonly used for the separation of mineral particles. Bubbles sparged in a pulp collect and carry hydrophobic particles to the top layer of a flotation cell, the froth zone. There is a strong correlation between the stability of the froth phase and the flux of solids. However, flotation units placed in series operate, as a whole, in a non-steady state regime with the concentration of particle decreasing from one cell to the next resulting in a decrease in froth stability, which can compromise the recovery of valuables. Organic chemical reagents, frothers, are generally added to prevent fine bubbles from coalescing and to increase the stability of the froth phase. Frothers represent the second largest group of mining chemicals. It is crucial to understand the resulting properties of the frother on the froth phase in order to select the most suitable reagent for a particular operation. The bubble coalescence dynamic of three different surfactants, 1-pentanol, poly (propylene glycol), and tri (propylene glycol) methyl ether, were investigated in this study. In the first stage, the stabilisation mechanism of bubbles in a solution of surfactant was investigated using a specifically designed experimental setup. The coalescence behaviour of bubble pairs was recorded using high-speed video imaging in which information such as the coalescence time and the deformation of the resultant bubble upon coalescence could be extracted. The results were then compared between the different surfactants for several concentrations. It is shown in a study that the coalescence time increases with surfactant concentration until the Gibbs-Marangoni effect is suppressed by bulk diffusion. Conversely, the oscillation of the resultant bubble was found to be affected only at concentrations at which the film is saturated. The implications of the effects of surfactant type and concentration on the coalescence time and bubble oscillation in froth flotation are discussed. Keywords: froth flotation, frother, bubble coalescence

Sep 1, 2012

By Mario Gerards

Maturing populations create an increase in the demand for the type of non-ferrous metals, which are used in the manufacturing of electronic products. The depletion of existing high-grade deposits, make it necessary to boost the efficiency of beneficiation processes and most importantly the yield (recovery rate of the value commodities). Increasing demand now makes it worthwhile to tap into resources, which were previously considered waste, for example secondary deposits such as tailing ponds and electronic waste. In order to achieve increased yields, increasingly finer, or even ultra-fine fractions have to be treated. In most cases, mineral characteristics such as size and density call for non-mechanical, high-capacity technologies to be used. There are various technologies that allow for the separation of fines and ultra-fines. This paper outlines the dynamics and efficiency of pneumatic flotation with emphasis on its application to the recovery of non-ferrous metals, from electronic waste. The conventional agitator flotation technology of an electronic waste processing plant was not able to recover ultra-fine non-ferrous metals satisfactorily, due to losses within the tailings. Because of its adaptability and its inherent suitability for non-ferrous metals, pneumatic flotation has been incorporated to the existing process achieving excellent results. The merit of the process lies in the state of the art technology, which does not utilize compressed air and any rotating parts, which results in a reduction in wear and energy requirement, both features of this innovative technology. In addition, the use of pneumatic flotation resulted in a significant reduction in residence time, when compared to mechanical flotation. Pneumatic technology is able to influence air bubble size in a flotation cell, by changing the speed and pressure of the slurry stream. Higher slurry velocities lead to the formation of smaller air bubbles, which is required for the successful flotation of ultra-fine particles. Conversely, decreasing the slurry velocity leads to bigger air bubbles. The optimum bubble size can be created according to different feed characteristics. This is important in case of feed fluctuations.

Sep 1, 2012

By Prasad Kopparthi, Narasimha Mangadoddy, Balraju Vadlakonda, A. K. Mukhurjee

"Column flotation (CF) is widely using equipment in mineral processing since many years. ERT technique facilitates non-invasive and nonintrusive visualization of different parameters in a column flotation. The hydrodynamic investigation of two-phase and three-phase are studied using electrical resistance tomography (ERT) coupled with pressure transducers in laboratory column flotation. Bubble size distribution, bubble rise velocity and gas and solids hold-up hydrodynamic parameters are extensively used for column flotation design and performance evaluation. The effect of superficial gas velocity, feed flow rate and slurry height in the column on mean gas holdup and its radial distribution has been analyzed for both two-phase and three phase flows. Influence of solid particles on gas hold-up and its complete elucidation of dispersion in the column are assessed. Experimental results show ERT coupled with PT is suitable as an online monitoring tool to provide useful information on the hydrodynamic parameters of the column flotation. The tomography images, which were generated using a modified sensitivity back projection algorithm, were employed to explore the parameter study in two phase flow in column flotation.Furthermore, the results also indicate that ERT is a very powerful tool for diagnosing the `inside' flow behaviour of gas-liquid two-phase and gas–liquid–solid three-phase flow in columns operating for a wide range of flow regimes.INTRODUCTIONColumn flotation is being widely used in mineral processing industries in last few decades. There has been a lot of attention in understanding the various mechanisms that take place during operation. Due to many reasons column flotation has been found to yield better performance than conventional flotation cells, particularly with fine particles (Honaker and Mohanty, 1996). Due to complex flow behavior in nature, the performance of column flotation influenced by on flow characteristics of the process, (Jena et al., 2008). Previously basic research is carried out to evaluate the effect of the hydrodynamic parameters on the performance of column flotation (Finch and Dobby, 1991)."

Jan 1, 2018

By L. A. Vaisberg

"Mining processing plants are the most high-performing industrial enterprises in the world economy system. Even at an average-scale mining enterprise, the grain-size separation equipment continuously processes 105 to 106 dissimilar mineral particles per hour. In separation by physical properties, their number increases by at least 10 to 50 times. Mathematical modeling of such a high flow of discrete particles is carried out using two different approaches: the discrete-particle and the phenomenological methods. The calculations demonstrate the possibility of handling big data when describing the processes of separation of granular material. INTRODUCTION The interest to the screening process and the process of formation of new screen designs in Mekhanobr is traditional since the moment of its foundation. It is symbolical that the first publication of the Mekhanobr proceedings in 1924 was the monograph dedicated to screens and screening products as such, which was the first one in the world at that moment. It was a book of Prof. L. B. Levenson, one of the founders of Mekhanobr, who headed the Technical Bureau of the Institute. Vibratory screening is the most mass process in the technologies of solid minerals processing, which determines significantly the energy demands of crushing and grinding cycles, and at some enterprises determines the quality of the final product, for example in case of crushed stone, coal or abrasive materials production. The general understanding and simulation of the process of poly-dispersed granular materials vibratory screening was developed at several conceptual levels taking into account the features of classification of materials with different size and density.Considering the real industrial processes of vibration screening, it shall be noted that at the sieve surface of the screen in the initial part of the deck the classification in a thick material layer (in natural conditions) occurs, which further transfers to a thin layer (free movement). In the process of screening of light minerals, for example coal or metallurgic feedstock, screening is mainly performed in the thick layer."

Jan 1, 2018

By P. N. Mohan Das, K. Harikrishna Bhat

"The major ilmenite reserves are located in India at Chavara (CH), Manavalakurichi ( MK) and Chatrapur, Orissa (OR). India stands first in terms of ilmenite reserves, which are estimated to be 278 million tonnes out of which, 142 million tonnes are processable. Mineralo-chemical analysis showed that Chavara ilmenite is the most weathered one with about 60% TiO2 while Chatrapur is the least weathered with about 50% TiO2. XRD and SEM studies of different magnetic fractions of these three mineral deposits established the co-existence of ilmenite with pseudorutile, rutile and haematite phases in substantially varying amounts. It is observed that the tropical weathering rather than the source rock difference has apparently played an important role in imparting major compositional and structural dissimilarities among the ilmenites in different places. Further, the chemical analysis, XRD and SEM characterisation of differently weathered samples of MK ilmenite separated by the magnetic fractionation showed that the degree of alteration was invariably associated with the decrease in magnetism, increase in the rutile phase and the change in Fe2+/Fe3+ ratio of ilmenite grains. Magnetically separated fractions when subjected to metallisation with carbonaceous reductant such as coke showed that the degree of reduction increases with the degree of alteration and with the decrease in the Fe2+/Fe3+ ratio.In the processing of ilmenite through the Becher process, aeration rusting of pre - reduced ilmenite is found to be the rate-limiting step thus, affecting the productivity and economy of the process. Investigations have proved that the addition of some organic compounds such as glyoxal, sucrose etc., to the system accelerates the reaction to such an extent that the rusting time has been reduced to less than half. The formation of acids by the these organic compounds during the rusting reaction was proved responsible for maintaining the pH of the solution in the range 3-4 at which iron hydroxide do not precipitate and block the pores in the reacting surface of the grain."

Jan 1, 2003

By M. R. Robben

Carbonates have gained significant economic importance for the human kind. On one hand over a hundred uses are listed for carbonates. On the other hand, carbonates host base metal deposits. Although the carbonates play a significant part in the development of those deposits, in the mineral processing they consume acid and cause selectivity problems during flotation and leaching. Carbonates also accompany other industrial minerals as waste rock. For all those cases it necessary to find a technique to separate carbonate as early as possible in the processing chain. In this paper, the applicability of near-infrared spectroscopy (NIRS) sorting for the separation of carbonates is discussed. NIRS sorting is a sensor-based sorting technique, in which particles are singularly detected by a sensor and then rejected by an amplified mechanical, hydraulic or pneumatic process. This technique can for example be implemented in the process as a pre-concentration step for coarse particle sizes up to 300 mm. NIRS sorting discriminates among materials based on the difference that exist between their spectral properties in the near-infrared (NIR). Vibrations of molecular bonds in carbonates cause characteristic spectral properties in the NIR, which makes carbonates detectable, possible to identify, distinguish and separate from other rock materials. The spectral properties can also be used to distinguish between different carbonate minerals and mixtures. If the spectral variations are large enough for detection, sorting based on NIRS is possible. Feasibility studies on sensor-based separation of carbonates in the processing of talc, borate, fluorite, marble, zinc-oxides, copper sulphide and iron ore as well as the discrimination of calcite and dolomite mixtures are conducted and indicate the high potential of NIRS sorting in the minerals industry. Keywords: carbonate separation, sensor-based sorting, near infrared spectroscopy, NIRS sorting

Sep 1, 2012

By Lev Filippov, Vyacheslav Severov, Inna Filippova

"Reverse cationic flotation is a very efficient method of beneficiation of oxidized iron ores when you need to separate hematite and quartz. This method can be also applied to reduce silica content in the magnetite concentrates obtained by wet low-intensity magnetic separation. However, cationic flotation in this case is less effective due to the presence of Fe-Mg-Al-bearing silicates as amphiboles in magnetite ores. These silicates are concentrated in magnetic products and determine the difficulties of their separation from iron oxides when amines and starches are used as collectors and depressants, respectively. The recalculation of the results of the electron microprobe analysis of three calcic Fe-Mg-Al-bearing amphiboles used to characterize cation distributions in structural units and to obtain structural formulas in accord with stoichiometric limits was conducted. The Mössbauer spectroscopy was used to examine the validity of the empirical estimation of cation distributions in amphiboles. The studied samples are metamorphic pargasite and ferrotschermakite and volcanic magnesiohornblende. The crystallographic analyses of the amphibole samples exhibited their heterogeneous surfaces explaining worse floatability of amphiboles with dodecylamine at pH 10. The electrokinetic measurements showed that the position of the isoelectric point of amphiboles is related to a substitution of Al3+ for Si4+ in tetrahedral sites and to an amount of Mg2+ cations in octahedral sites. Thus, the dodecylamine adsorption onto amphiboles through electrostatic interactions is mainly affected by a distribution of these cations in tetrahedral and octahedral sites of amphiboles. In addition, the effect of starch on the depression of Fe-Mg-Al-bearing amphiboles during flotation can be attributed to the presence of metal ions on the amphibole surface, which are capable of forming strong chemical complexes with starch molecules."

Jan 1, 2014

By Xuliang Yang, Yuemin Zhao, Bo Zhang, Liang Dong, Cheng Sheng, Gongmin Li, Zhenfu Luo, Yaqun He, Chenlong Duan

Coal plays an important role in the primary energy consumption of all over the world. In 2012, coal reached the highest share (29.9%) of global primary energy consumption since 1970. Coal burning mainly contributes to the emission of SO2, NOX, Hg and other impurities that jeopardize the future of environment. . Beneficiation before coal utilization is the most economical and effective technology for removing the hazardous material and gangue. In this paper, a novel process of dry beneficiation based on gas-solid two-phase flow composed of the compound dry cleaning separator (FGX), the air dense medium fluidized bed separator (ADMFB) and the vibrated fluidized bed with autogenous medium (VFB) is proposed. The main equipment and the flowsheet of the united system are described in detail. Separating principle of the FGX, ADMFB and VFB devices are all based on gas-solid two-phase flow. In FGX, gassolid suspension is composed of continuous gas flow and coal powder in feed coal. Large size coal (+6- 80mm) can be pre-separated effectively, and large size gangue can be removed effectively. Moreover, - 6mm particles fed serve as autogenous medium in FGX. The probable E value is 0.13 for -80 mm raw coal. In ADMFB, magnetic powder with -0.3 + 0.045 mm size fraction and coal powder in feed coal are compound medium solids. The separation density can be adjusted and controlled according to properties of raw coal. -50 + 6 mm raw coal can be cleaned efficiently, the probable E value is 0.05. In VFB, -6 + 1 mm coal can be separated. Generally, -80 mm raw coal can be cleaned efficiently in the united system based on gas-solid two-phase flow.

Jan 1, 2014

By A. V. Bauman

"Important for thickening processes is the ability of slurries to form under certain conditions aggregation and sedimentation stable systems. Substantial part of difficult to sediment solid particles in such systems may be in colloidal state. The technique to study the sedimentation and aggregative stability of the slurry developed by the author with co-authors makes possible to define kinetics of changes in the aggregative stability of the system with solid phase varying concentration in it and produce data on sedimentation stability of the system in preliminary investigation of the thickening process. Research of aggregative and sedimentation stability of the slurry complement standard methods of laboratory studies to prevent errors in development of water-slime thickening balance and water circulation to design new and upgrade existing processing plants. Statistical analysis of process audits of more than one hundred upgraded and newly commissioned processing plants carried out in recent fifteen years showed that more than two-thirds of problems arising in commissioning the processing plants are associated with misdesign and errors in thickening and water circulation system. Among the main reasons of process design failures are: non-conformity of actual characteristics of the raw material to design characteristics, low quality of preliminary studies at the stage of sedimentation process simulation, design failures, wrongly selected equipment for the thickening and water circulations systems. As of today a number of problems associated with laboratory studies of sedimentation process, first of all, with interpretation of precipitation curves produced at the stage of laboratory refinement of the thickening process have been pinpointed. (Bauman A.V. Outstanding issues in design of thickening and water circulation diagrams in processing plants // Ore processing. 2016. ?3 P. 58-62) ?????? ?.?. ?????????? ??????? ?????????????? ???? ???????? ? ??????????? ?????????????? ??????. // ?????????? ???. 2016. ?3. ?. 58-62))"

Jan 1, 2018

By Hernán Menares, Diego Hernández

"Over the last few years, the copper mining industry has been facing a changing scenario with respect to both the market and society which has resulted in taking a closer look at the way in which mining is being done. The cycle of high metal commodity prices of the last decade left the industry with high costs. Together with increased environmental and social requirements, a decrease in ore body quality, scarcity of resources such as human capital, water and energy, has resulted in an ever-increasing challenge to make a profit out of new ore bodies but also to maintain the current operations in the longer term competitive. The major challenge is to create value for all stakeholders, exploiting ore bodies that nowadays are not considered economically attractive, which applies to both new ore bodies and existing operations, but in a sustainable way. In order to achieve this objective, it is necessary to approach the mining business differently in five main areas: (1) operational efficiency through better use of installed equipment and skilled labor force; (2) efficient use of energy; using opportunities for alternative energy sources and efficient design; (3) efficient use of water; diminishing losses and use of seawater as an alternative source; (4) minimizing environmental impact by eliminating effluents and controlling dust emission; and (5) a more closer, proactive and collaborative relationship with the communities allowing them to be an active player in the solution to assure a sustainable business in the long term. This presentation will show how Antofagasta Minerals is facing these challenges with a long term strategy that includes all of the above mentioned aspects and that is allowing the company to exploit its mineral properties in an efficient and successful way."

Jan 1, 2014

By Shuji Owada, Mayumi Ito, Idemitsu Kosan Co. Ltd., Takehiko Nishimu, Sadayuki Shinozaki, Takashi Ando, Tomoe Ota

"fElectrical disintegration (ED) by high voltage electrical pulse is a relatively new technique which was demonstrated by Tomsk and Mekhanobr in the 1960’s and has been investigated in detail by Andres in the 1990’s. In the ED, the electrodes should contact to the targeted material and the energy of high voltage pulse is charged directly to the material. It has been reported that the ED is quite efficient to improve liberation of composite materials, because electrical current passes often through the conductive part and/or along the phase boundaries. Theoretically, the energy required in the ED should be lower than in the other mechanical breakage methods, because breakage occurs basically by tensile strength in the ED while in the other mechanical methods it does mainly by compressive strength which is generally ten times or higher than tensile strength.Coal, involving many kinds of mineral matters, is considered to be one of the targets for the ED to apply to. In Japan, national “Hyper-Coal Project” is now running, in which ultra-clean coal (less than 200ppm of ash, 0.5ppm of Na and K, and 2ppm of Ca) is planned to produce by combining advanced coal preparation and liquefaction technologies for the purpose of direct injection of coal combustion gas to turbine. The ED is one of the major techniques to be developed in this project, since mineral matters must be liberated before introducing to the following advanced separation processes. Liberation is important also for the utilization of middling coals generated from usual coal preparation plants. The application of the ED to the middling coals is considered effective for upgrading these coals with higher liberation degree and less energy input."

Jan 1, 2003

By Mohan Ram

Structural impurities in the crystal lattice of rock phosphate of Indian origin is a great challenge for beneficiation and practically possesses remote scope of upgradation to the desired level for industrial utilization. There is a wide occurrence of rock phosphate in different parts of India with different characteristics viz. siliceous, carbonaceous and ferruginous. The structural cationic replacement in the composition of apatite is due to the exchangeable cations present in the external impurities associated with the rock phosphate ore. The Indian rock phosphate ore from Purulia district, West Bengal is characterized as unusual structural composition due to the exchangeable cation in its composition. The elemental distribution of ore exhibits the disproportionate ratio of P2O5 and CaO which is 5.88: 3.31 in reference to the theoretical composition of P2O5: CaO in apatite which is 4.23: 5.55. The substitution by trivalent Al+++ cations within the structure of apatite in place of divalent Ca++ is found upto 18% and substitution of exchangeable cation in place of PO4 and F ion by CO3/SO4 is found upto 0.1% and OH ions upto 0.2% respectively in a lattice of apatite thereby diluting the grade of rock phosphate and restricting its industrial use even after beneficiation. This paper reveals the unusual compositional features of rock phosphate under study and is a guideline to the mineral industries using such rock phosphate. Keywords: external impurities, exchangeable cation substitution, structural compositional features, electron probe micro analyzer

Sep 1, 2012