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By Sergey Ulianov, Arkady Senchenko, Alexey Shvets, Arkady Bakotin

"This paper is devoted to ultrafine grinding of processing products. This process allows one to include into operation complex ores which earlier were considered as inefficient and economically inadvisable to treat. Fine dissemination of valuable component often does not allow its liberation via standard grinding in ball mills, and therefore requires modern methods of ultrafine grinding (UFG). An example of successful ultrafine grinding usage is its application for crude flotation concentrates regrinding before cleaner flotation stages. A problem often arises with a commercial copper concentrate production in the course of copper ore flotation. Crude flotation concentrate regrinding in a ball mill does not provide for good liberation of the material before cleaner stages. UFG application allows one to get commercial copper concentrate with copper grade of 20% and higher. Another example of ultrafine grinding application is its usage for highly refractory pyrite product received after gold-lead scavenger flotation of polymetallic ore. Earlier this product treatment was economically inefficient. At current application of ultrafine grinding down to 85% minus 20 µm and subsequent gravity processing it is possible to pass major part of gold (73.4%) into concentrate. The constraining factor for UFG application in processing may be the chemical activation of minerals. In the result of this, flotation selectivity may decrease. Therefore ultrafine grinding application extends the areas of efficient usage of metallurgical processes. New technologies allow increasing the level of valuable metals recovery."

Jan 1, 2014

By A. F. Usov

A potential of electric pulse disintegration in benification used for primary deposits ores containing precious metals is shown. Of special significance is that PGM and gold grains, being highly plastic, are easily liberated and are not smeared on the disintegrated rock fragments surface. It al-lows gravity separation, which is less expensive and more efficient, to be used instead of chemical processing, which is expensive and environmentally faulty.

Jan 1, 2014

By Jiongtian Liu, Jianjun Wu, Yongzhou Wan, Li Feng

"Mechanical Thermal Expression (MTE) is a developing non-evaporative lignite dewatering technology. It has been shown to effectively dewater high moisture content in low rank coals via the application of mechanical force and thermal energy at elevated temperatures. In this paper, the dewatering behavior of Yunnan Xiaolongtang lignite during the MTE-process was studied. Furthermore, how variations in temperature and pressure during the MTE process affect the surface oxygen functional groups and pore structure were also discussed using Fourier transform infrared spectrometer (FTIR) and mercury intrusion porosimetry (MIP). Increases in MTE temperature and pressure resulted in significant reductions in residual moisture content and moisture holding capacity, along with the increase of fixed carbon content and reductions of other elements content, especially oxygen content, which have been largely attributed to the destruction of the surface oxygen functional groups and porosity in lignite. The optimized technology conditions are temperature 150~220°C and pressure 7~10MPa. The residual moisture content of the lignite treated by MTE under the conditions of 200°C and 10MPa is decreased to 8%, while the dewatering rate exceeds 76 % and the calorific value approaches 22 MJ/kg. The experimental results offer a deeper understanding of the influence of process parameters on the lignite stuctures and properties. The reduction in residual moisture content, surface oxygen functional groups and pore volume under increasingly severe MTE conditions are suggestive of the structure changes that accompany increased coalification (rank) within the lignitic range."

Jan 1, 2014

By W. Fander, Zhonghan Zhang, T. Choo, J. Enraght-Moony

"This paper describes the mineralogical and metallurgical procedures used to determine the recovery and concentrate grade of heavy oxide minerals occurring in lode deposits. The data produced also provide vital information to the processing engineers, which allows them to develop the most suitable flow sheet for that particular heavy mineral, here called an Economic Oxide Mineral (EOM). It demonstrates how results are interpreted to ensure that the proper process is used at each treatment stage to optimise recovery and to produce the most suitable concentrate at that point. Reference is made to some of the current equipment and techniques that can be used to process EOMs. The paper shows that when assessing the economic potential of a new ore body, or existing ore treatment plant, ore characterisation (OC) is necessary. This is especially true for EOMs such as cassiterite (SnO2), wolframite ((Fe, Mn, WO4,) pyrochlore ((Na,Ca)2Nb2O6(OH,F)), and tantalite (MnTa2O6) where often what seem to be small changes in ore types can have major effects on recovery and concentrate grade. Due to advances in flotation technology scheelite (CaWO4) in some deposits can be less vulnerable to OC variability than other EOM’s. Thorough mineralogical examination is shown to be the fundamental basis of correctly undertaking OC. This is because mineralogical analysis identifies each of the steps required to ensure that all ore types and zones are recognised, and differences explained, and shows the benefit in using reference samples to compare differences in the ores. The OC methods used for EOMs containing metals such as tantalum, tin, tungsten and niobium are similar; if two or more of these EOMs occur in one deposit as separate minerals, then OC will show when and how these minerals should be separated. The OC techniques described for EOMs can also be tailored for other heavy minerals, precious metals and graphite."

Jan 1, 2014

By Sergio Castro, Janusz Laskowski

In the flotation in highly concentrated electrolyte solutions not only ionic strength but also chemical composition, flotation pH and mineral properties play an important role. As a result an improvement or depression may be observed. A strong improvement in the floatability of hydrophobic bituminous coals and other inherently hydrophobic minerals is characteristic for the "salt flotation process", which is carried out in concentrated electrolyte solutions at natural pH and without addition of any flotation reagents. However, pH is a key factor when saline and hipersaline waters with hydrolyzing metallic ions are used as process water. In the case of flotation of Cu-Mo sulfide ores in seawater, molybdenite is strongly depressed by the Mg2+ hydrolysis products when pH is raised to depress pyrite. Process water with a high content of Mg2+ and Ca2+ ions, and this also includes seawater, have deleterious effect on the anionic flotation of industrial minerals with fatty acids. The flotation of potash ores is carried out in NaCl-KCl saturated brine (6-7 mole/L of NaCl and KCl) with the use of long-chain amines. Such a high electrolyte concentration changes dramatically the amine Krafft point making the collector insoluble in brine; its mode of action entirely differs from that in conventional flotation processes.

Jan 1, 2014

By Jan Cilliers

The demand for minerals has never been higher. Moreover, the rate at which this demand is growing is unprecedented, and expansions and new mines will be required to fulfill these growing needs. This, in turn requires a skilled engineering workforce that can develop and operate minerals extraction processes to utilise effectively more complex ores. The International Mineral Processing Council (IMPC) has established a Commission on Mineral Processing Education to consider the global challenge of ensuring an adequate supply of well-trained mineral processing engineers. The Commission has, for the past four years, been collecting international information of the recent mineral process engineering supply position and with a view into the near future. The data collected by the international Commission members are as follows: ? Undergraduate student numbers in minerals engineering ? A breakdown of their male/female ratio ? The fraction of the students from each course that enter the minerals industry ? Teaching staff numbers and age profile This data has been collated and analysed, and the findings are presented. It is clear from the analysis that the supply situation is very different in different regions of the world, and that great opportunities exist for targeted recruitment into the industry to meet the future talent demand. Further, an attempt at correlate the supply of minerals engineers based on the local mineral production rate is shown, which shows that there are clear outliers.

Sep 1, 2012

By Dave Deglon

The Western Cape Mineral Processing Facility (WCMPF) is a collaborative educational initiative between the Departments of Chemical Engineering of the University of Cape Town, the University of Stellenbosch and the Cape Technikon. The WCMPF was established in 1989 with the aim of improving mineral processing education in the Western Cape. Since its inception the WCMPF has had a number of successes in this area, especially in improving the quality of mineral processing practical training. In addition, the WCMPF has played an important role in promoting liaison and interaction between tertiary educational institutions teaching mineral processing in the Western Cape. Over the past decade the WCMPF has played a key role in the education of over five hundred mineral processing graduates and diplomates. This paper presents an overview of the activities of the WCMPF and attempts to encapsulate the ‘lessons learned’ from over a decade of successful functioning as a collaborative educational initiative in mineral processing.

Jan 1, 2003

By R. C. Miranda

This paper intends to demonstrate the applicability of tools for advanced process control and online particle size image analysis in crushing and autogenous grinding circuits. In a crushing plant, cameras are installed in the conveyor belts of the circuit products. The vision system continuously processes the acquired images and thus obtains the variation of the size distribution curve. From these measurements, the advanced control system can operate, for example, at the opening of the crusher, in order to keep the P80 in the desired range. In addition, through the power information and level of the crusher's chamber, it is possible to increase the capacity of the crushing circuit. If the crusher is not equipped with an automatic opening adjustment, a warning may be issued to the operator to provide this setting manually. In mineral processes that use autogenous and semi-autogenous grinding for fragmentation, obtaining online F80 through the vision system allows for manipulating the parameters of rotation speed and solids concentration, through which the amount of material at the critical particle size that is produced can be controlled. In addition, the noise produced in the mill can be measured and controlled. Thus, it is possible to prevent breaches and to optimise the mill capacity for grinding. Image analysis combined with an expert system that translates this information and acts to seek the most appropriate particle size distribution, brings greater stability to the process optimising the capacity of the equipment, which allows for significant gains in production.

Sep 1, 2012

By Xiaoping Xu, Tiansong Dong, Guosheng Wang

"Jianfengpo tin ore is located in Jiangxi Province, China. The cassiterite is fine and dispersed. It is hard to separate marmatite from a variety of sulfide minerals. Because the iron-containing sulfide minerals including pyrrhotite, pyrite and chalcopyrite are detrimental to the improvement of the grade of zinc concentrate. Besides, the presence of the iron oxides and ferro-carbonate minerals results in the difficult beneficiation of tin. Therefore, Jianfengpo tin ore is a kind of refractory cassiterite polymetallic sulfide ore. According to the properties of Jianfengpo tin ore, the technology process of "Sulphide ore preflotation-Bulk flotation of sulphur and zinc-Separation of sulphur and zinc -Magnetic separation-Gravity concentration" was developed to recover the valuable materials including marmatite, pyrite, magnetite, cassiterite and indium comprehensively. For the feed ore containing 0.87% Sn and 0.70% Zn, a zinc concentrate of 44.56% Zn with a recovery of 69.10%, a high-grade tin concentrate of 54.38% Sn with a recovery of 53.03% and a low-grade tin concentrate of 6.54% Sn with a recovery of 1.25% can be achieved in the batch flotation tests. In the industrial tests, for the feeding which contains 0.55% Sn and 0.65% Zn, the tin concentrate of 49.10% Sn with a recovery of 48.52% as well as the zinc concentrate of 45.11% Zn with a recovery of 60.10% can be produced. Thus some pyrite and magnetite concentrate are recovered as well. So Zinc, tin, sulphur and iron ores are recovered effectively by the technology."

Jan 1, 2014

By Brochot. Stephane, Manuel Gonzalez Fernandez

"HPGR (High-Pressure Grinding Rolls) is widely used today for grinding of various kinds of ores such as iron ore or base and precious metal ores. It can be used as first stage of grinding replacing tertiary crusher and SAG mill, but also as regrinding stage to enhance mineral liberation. In addition to better energy efficiency, the advantage of HPGR is to produce much more internal particle fractures allowing faster leaching as it has been demonstrated for some gold ores. This grinding mode of compression and fracture generation also promotes mineral liberation without overgrinding. Mineral processing modelling and simulation associated to detailed ore characterization constitute a powerful tool for plant design and optimization. The mathematical models of the units of operations (grinding and separation) have to reproduce the mineral deportment for which the mineral liberation plays a central role. The present paper is focused on the HPGR modelling with the objective of plant optimization or advanced design from pilot plant tests. The traditional approach of the population balance linked to the energy dissipation and the residence time distribution is generalized in association with a mineral liberation model. The effect of the specific HPGR breakage matrix and grinding function on the mineral liberation rate is discussed and compared to the tumbling mill. The implementation of this mathematical model into a plant simulation tool is illustrated by the example of the optimization of an iron ore concentrator."

Jan 1, 2014

By Lev O. Filippov, Inna V. Filippova

"Flotation of metal-organic precipitate in column is sensible to the hydrodynamic conditions determined by the diameter and the dispersion of rising bubbles. Thus, the dissipation energy in the system resulting of ratio between superficial fluid velocities (gas and feed) in the column is the main parameter for precipitate flotation in pilot or industrial scales. The suggested limiting factor is the aggregate stability under the turbulence created by the rising bubbles. The stability of precipitate is related to the structural organisation of aggregates, which determines the size distribution of particles during precipitation and flotation stages.Structural evolution of Mo precipitate and the destruction phenomenon were described by using of the various fractal dimensions. The fractal studies allow the detection of a structural scaled organisation of the precipitate flocs. The fractal dimension of the particle mass distribution Dm=1.94+/-0.15 suggests, for the floc structure, a cluster-cluster aggregation process either with restructuring or breakage phases.The destruction process, which occurs for the lowest values of the dissipation energy E (0.02 . 0.05 W/kg) was characterised by a fractal dimension Dg of size distribution. Besides, the destruction of floc produces very fine particles, and thus induces the difficulties of bubble-particle collision during the precipitate flotation in column."

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

By Lawrence Bbosa, Aubrey Mainza, Indresan Govender

"Positron Emission Particle Tracking (PEPT) and the Discrete Element Method (DEM) are used to develop a probability based model for the power draw of a tumbling mill. Experiments are conducted using dry spherical glass bead charge in a laboratory scale tumbling mill, which is mounted with a torque transducer and tachometer to measure mill power. Particle tracking information from PEPT is used to reconstruct the motion of glass beads and infer the overall charge behavior, while DEM is employed to simulate particle motion and interaction, with collision mechanics calculated using the Hertz-Mindlin contact model. For both sets of data, the product of torque and average angular velocities in discrete cells are accumulated to obtain mill power. This method is found to be within statistical agreement with measured power for all tests. The information from both techniques is then used to develop a model for the power draw as a function of particle size, mill speed and volumetric filling. Predictions of the model match well with measured and calculated values. The model is found to predict mill power within close agreement with measurement and follows trends consistent with existing work on tumbling mill modelling."

Jan 1, 2014

By Luis Cáceres, Genny Leinenweber

"We have designed a planar perpendicular flow cell for electrochemical measurement of a mineral available as a fine powder. The working electrode consisting of mineral powder supported on a carbon paste surface as a 4 mm diameter disk, was concentrically positioned inside a vertical tubular reactor. The counter electrode was a 316L tube embedded in the body cell. The supportive media was a 1.2:1 mixture of candle wax and graphite powder respectively, which is a good electrical conductor. The concentrate electrode as a film attached on a carbon paste disk was prepared rubbing the surface carbon paste against dried powdered mineral. An Ag/AgCl 1 M KCl cell as a reference electrode was attached to the body cell by using a fast coupling fitting. A stable flow rate was achieved using a frequency inverter to drive the pump motor. The flow through the cell verified to be laminar due to the Reynolds number in the cell flow passage. Cyclic voltammetry from - 1200 a 600 mVSAgE were measured using a carbon paste with and without mineral attached to the surface. The main findings of this work were: a). Electrochemical measurement of mineral powder in contact with flowing samples was easily achieved using ground mineral. This is important where massive samples are not available. b). The voltammetric curve features of ground mineral coincided with reported data. c). The working electrode could be quickly replaced while maintaining very good reproducibility."

Jan 1, 2014

By Q. R. Chen

Wet processes are commonly used in coal preparation field home and abroad. Dry coal cleaning technology is very necessary in China because more than 2/3 of coal resources deposited in arid areas, which are difficult to separate coal with wet processes. A particular interest of this article is the discussion of separation research development of dry coal cleaning in China, such as an air dense medium fluidized bed (ADMFB) beneficiation technology, a compound dry (pneumatic) separation technology and a triboelectrostatic separation technology. The fundament and importance of dry coal cleaning methods above were introduced. On the basis of analyzing parameters which influence the performance of separators, including that of structure, technologic and operating, the separation research status of dry coal cleaning methods, especially the ADMFB beneficiation technology, were discussed and reviewed. The recent developments, especially the fluidized bed beneficiation for <6mm fine coal with an external energy assisted, including a vibrated fluidized bed and a magnetically fluidized bed, and the triboelectrostatic separation for <1mm fine coal are also introduced. The study and application results in China show that dry coal cleaning technologies can efficiently beneficiate different coals with different sizes. The ADMFB can separate >6mm coarse coal with an E value of 0.05~0.08, the external energy assisted fluidized bed can separate <6mm fine coal with an E value of 0.07~0.09, the triboelectrostatic technology can efficiently separate <1mm fine coal, and the compound dry separation technology can efficiently separate >3mm coal with a easy washability. The dry coal cleaning provides an efficient and lower cost clean approach for coals distributed in arid areas.

Jan 1, 2014

By J. Y. P. Leite

In a small-scale mining in Brazil?s northeast, scheelite were exploited since 1940?s using a traditional gravity concentration flowchart (composed by jigs and shacking tables) that operates with low efficient for fine particles. Tailing of this plant was submitted to chemical, mineralogical and size characterization. Results pointed 50% smaller than 74µm with a grade of 0.11% WO3. The particle?s size is an important operational variable to heighten recuperation by shacking tables. Tests using Falcon SB40 centrifuge concentrators and shacking table were realized, optimizing their operational variables. Based on the tests results a new flowchart was proposed for concentrating and tailings recovery.

Sep 1, 2012

By J. Leite

In a small-scale mining in Brazil?s northeast, scheelite were exploited since 1940?s using a traditional gravity concentration flowchart (composed by jigs and shacking tables) that operates with low efficient for fine particles. Tailing of this plant was submitted to chemical, mineralogical and size characterization. Results pointed 50% smaller than 74µm with a grade of 0.11% WO3. The particle?s size is an important operational variable to heighten recuperation by shacking tables. Tests using Falcon SB40 centrifuge concentrators and shacking table were realized, optimizing their operational variables. Based on the tests results a new flowchart was proposed for concentrating and tailings recovery.

Sep 1, 2012

By Kazutoshi Haga, Atsushi Shibayama, Altansukh Batnasan

"The aim of this study was to develop a hydromellurgical processing for removal of arsenic from high-arsenic copper sulfide ores and concentrates, providing increase in copper recovery. In this study, three different enargite ore samples containing 28.2–46.7% copper, 1.9–15.0% arsenic and 10.6–27.5% iron were used to determine optimum conditions for the extraction of copper and removal of arsenic. High pressure oxidative leaching process was preformed using various leaching reagents such as sulfuric acid (H2SO4), ferric sulfate (Fe2(SO4)3), hydrochloric acid (HCl), ferric chloride (FeCl3), sodium sulfate (Na2SO4), sodium chloride (NaCl) solutions and distilled water (DW), respectively, under the fixed conditions which were selected to be as follows: NaCl concentration, 0.34 M; concentrations of other leaching reagents, 0.1 M; particle size, -45 ?m; pulp density, 100 g/L; agitation speed, 750 rpm; leaching temperature, 160 ?C; leaching time, 60 min and total pressure (oxygen gas and vapor pressure) into an autoclave, 1 MPa. Results show that under the leaching conditions, more than 90% of copper leaching was achieved with lower than 2% arsenic content as a consequence of the formation of arsenic precipitates in a solution of Fe2(SO4)3–NaCl. It was determined that copper, arsenic and iron concentrations in the pregnant leach solution were 42 g/L, 0.3 g/L and 0.3 g/L, respectively. As a result, it can be concluded that the Fe2(SO4)3 solution in the presence of NaCl or FeCl3 are more efficient leaching media compared to other leaching agents under the high pressure oxidation conditions, because of their high copper recovery and lower arsenic level in the pregnant leach solution.INTRODUCTION Generally, copper is usually produced from copper sulfide ores by a combination of several processes which are flotation and smelting followed by refining [1-3]. Arsenic content in copper sulfide ores tends to increase due to the depletion of high grade copper deposits, hence conventional mineral processing and metallurgical processes cannot effectively treat these ores containing high levels of arsenic to obtain consistently high purity copper concentrates. Because high levels of arsenic in copper ores/flotation concentrates reduces the value of concentrates due to the restriction of smelting process and causes it to be a source of environmental pollution [4-6]. From this point of view, the known way of prevention against high-arsenic copper sulfide concentrates in further metallurgical treatments is to develop economically and environmentally competitive technologies for removal of arsenic impurity from copper sulfide ores before treating the ores/flotation concentrates by the pyrometallurgical routes."

Jan 1, 2018

By X. L. Wang

Hydrothermal method was applied in the preparation of calcium sulfate whiskers in airtight re-actor using gypsum as primary materials. The optimum conditions of preparation are as follows: pH value 9.8~10.1, concentration 5%, material size 18.1µm, which were determined by the analysis of the diameter of CaSO4 whiskers through SEM. On these conditions a product of ultrafine CaSO4 whiskers with diameter of 0.19µm and aspect ratio of 98 is obtained. Ultrafine CaSO4 whiskers with different concentrations, modified by titanate NDZ-401, were added into polypropylene as intensifier and composites of Ultrafine CaSO4 whiskers/ polypropylene were prepared by melting-extruding method. Mechanical performance of the composites was tested and surface morphology of the composites was observed by SEM. The results indicated that impact notched izod of the composites was enhanced by 49.5% compared with pure polypropylene when 10.0% Ultrafine CaSO4 whiskers were added into polypropylene and toughening effect was very remarkable. Dispersion behaviour and interface phenomenon of Ultrafine CaSO4 whiskers in polypropylene matrix were investigated by SEM. The results indicated that Dispersion performance of Ultrafine CaSO4 whiskers modified by titanate NDZ-401 in polypropylene matrix is good, which improved mechanical performance of composites to some extent.

Jan 1, 2014

By M. Brozek

The particle settling velocity is the argument of separation in such processes as classification and enrichment in jigs. It characterizes material forwarded to the separation process and belongs to the so-called complex arguments because it is the function of particle density and size. i.e. the function of two simple arguments. The affiliation to a given subset is determined by the values of two mag-nitudes and the distribution of such argument in a sample is the function of distributions of particle density and size. The paper will present a method of determining the distribution of settling velocity in the sample of spherical particles for the turbulent particle motion in which the settling velocity is expressed by the Newton formula. Because it depends on density and size of particle which are random variable of certain distributions, the settling velocity is a random variable. Applying theorems of probability, concerning distributions of function of random variables, the authors will present general formula of probability density function of settling velocity for the turbulent motion and particularly calculate probability density function for Weibull?s forms of frequency functions of particle size and density. Distribution of settling velocity will calculate numerically and perform in graphical form.

Jan 1, 2014