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By Cagri Emer

In conventional mechanical flotation cells, when the size of particles exceed a particular value, that is of the order of 100 µm for metal sulphides, the recovery of particles decline rapidly. It appears that the turbulence in the agitated vessel is sufficiently intense to rupture the forces of attraction between the particles and the bubbles, so the large particles are flung off the bubbles in the turbulent field. It has recently been suggested, that a fluidized bed would be a very favorable environment in which to contact bubbles and the particles. In a fluidized bed, particles are supported by rising flow of fluid, which separates them from each other and allows them to move freely while remaining close together. In this novel method, bubbles injected into the fluidized bed are able to rise through it, colliding with hydrophobic particles, transporting them to the top of the column where they can form a froth layer that overflows into a launder. The flow in a fluidized bed is generally slow and nonturbulent, and preliminary experiments have shown, that it is possible to collect mineral particles as large as 1 mm and coal particles as large as 5.5 mm. If the upper particle size limit can be extended, there could be significant reductions in the overall energy consumption in concentrators. Calculations show for example that if the top size for flotation could be increased from 100 µm to 400 µm, there would be a reduction in grinding energy of the order of 40%. It is therefore, important to study the mechanism of coarse particle capture in fluidized beds. In this work, the factors governing the capture rate of particles, particularly the particle and bubble size, the fluidization velocity and the superficial gas velocity have been investigated, and the results will be presented.

Sep 1, 2012

By S. J. Neethling

"Liberation is a key driver in all mineral separation processes as it limits the maximum possible grade for a given recovery. In flotation, this is further complicated by the fact that it is surface exposure of the floatable minerals that determines the ultimate performance. Liberation, grade and surface exposure are commonly quantified using Scanning Electron Microscopy coupled to Energy Dispersive X-ray spectroscopy (SEM/EDX) analysis of polished sections. The intrinsically 2D nature of this technique can result in significant sampling errors and stereological effects that can affect the quantification of the ore’s textural characteristics. X-ray micro-Tomography (XMT) is an imaging method that can non-invasively and non-destructively delineate ore fragments in 3D, thus providing an alternative method that eliminates the need for stereological corrections and readily provides surface exposure. A methodology and automated algorithm were designed for extracting this information from images of closely packed particles, thus allowing samples containing a large number of particles to be assessed.The main drawback of XMT is that, unlike SEM/EDX, it cannot directly measure the mineralogy of the sample, instead producing a 3D X-ray attenuation map. We therefore also present an algorithm for calibrating the thresholding of the XMT images based on SEM/EDX images of sections through the same sample, thus allowing the liberation analysis to be carried out on a 3D mineral map in which the uncertainty in the mineral assignment is small and statistically quantified.The methodology was tested on low grade porphyry copper ore as this is both an industrially relevant and traditionally difficult system to quantify using XMT due to the similarity in the X-ray attenuation of the sulphide species, especially the pyrite and chalcopyrite. As each 3D volume imaged contain 100-1000s of grains, large data sets can be readily produced. By dividing these particles into classes based on both their surface exposure and grade, the extent to which there is preferential breakage of the particles can be assessed—an important consideration if sufficient surface liberation for good flotation performance is to be achieved at coarser particle sizes. It is also shown that erroneous conclusions can be drawn when basing the analysis on 2D sections through the particles."

Jan 1, 2018

By S. P. Nagaeva, A. V. Kuptcova, O. Yu. Poperechnikova

"The present paper contains study results of gold morphology and grain size distribution in flotation concentrates produced from original ore samples from deposits of different genesis. Pre-concentration methods were used with selective dissolution of rock minerals and mineral heavy medium separation to obtain statistically valid data on gold grain size and morphology in concentration products. Special attention is given to study of flash flotation concentrates that is mainly used for coarse gold, underextracted in gravity circuit. Analysis of geometrical optics has allowed to establish that during flash flotation gold grains more than 150 µm can be extracted from 10 to 35%, and in some cases single gold grains above 300 µm. INTRODUCTION Distinctive features of gold that have a significant impact, and in some cases, decisive influence on its recovery into saleable products are mineral shape, grain size and morphology of metal particles, paragenetic associations of gold. Peculiar feature of coarse gold is its easy extraction during grinding from associated mineral components like quartz, sulphide and other and almost complete recovery into gravity concentrates (Lodeischikov V.V., 1997). Morphology of native gold is so diverse that different gold grains are better extracted using different methods of concentration. Compacted and rounded particles are easily processed using gravity concentration but low cyanidable and hard to process using flotation. On the contrary, lamellar, flake, dendrite and capillary aggregates of high specific surface are easily cyanidable and under definite conditions it has strong floatability (Lodeischikov V.V., 1997). Flotation of gold-containing sulphide minerals and free gold takes place simultaneously during flotation concentration. In case of low-sulphide ores, native gold takes the basic load, having the high density (15.6 to 18.3 g/cm3, for pure gold – 19.3 g/cm3) it has limited size and morphology for successful flotation. It is known that flake gold and fine-grained gold up to 0.1 mm are easily extracted (Lodeischikov V.V., 1997). Authors of the present paper performed a study of gold granulometry and morphology in flotation concentrates produced from gold-containing ores from two deposits of different types: gold-copper oxidized hematite ores and low-sulphide gold-quartz ores. Ores are different by both host rock composition, mineralogical and petrographic features, gold grade in mineral assemblage and morphology and size of precious metal. Common for both ore types is low-sulphide content and presence of free gold."

Jan 1, 2018

By S. H. He

This paper focuses on the influence of pulp oxygen content on the separation of pentlandite and pyrrhotite contained in two different process streams in the Clarabelle Mill, operated by VALE INCO. The two process streams are (i) the scavenger cleaner feed, the product of regrinding the thickened, scavenged concentrate and the B cleaned tail produced from treating the non-magnetic fraction of the milled run of mine ore, and (ii) the magnetic concentrate which is the magnetic fraction of the milled run of mine ore. In the Clarabelle Mill, sulphite (SO32-) and TETA (triethylenete-tramine) are together used to selectively depress pyrrhotite from pentlandite. These depressants pre-ferentially decompose collector and/or sulphur enriched species at the pyrrhotite surface, an appar-ently essential mechanism in pyrrhotite depression from the scavenger cleaner feed stream. Selectivity in depression may originate from differences in the electrochemical rest potential of pyrrhotite and pentlandite. As both minerals are susceptible to oxidation, aeration in conditioning and flotation plays a key role in selective flotation. Important differences in the flotation behavior of pentlandite and pyrrhotite from the magnetic concentrate and the scavenger cleaner streams are highlighted in

Jan 1, 2014

By Kym Runge, Wei Huang, Fengnian Shi, Christian Antonio

"This paper presents an emerging High Voltage Pulse (HVP) technology for ore pre-treatment. Unlike previous studies where HVP was utilized as a crusher to pulverize ore particles to micron size ranges for downstream processing, the researchers at the Julius Kruttschnitt Mineral Research Centre (JKMRC) use HVP to enhance ore processability. Application of relatively low levels of HVP energy to selectively break mineralized particles from barren rocks, followed by size-based screening separation enables the feed ore to be split into high grade and low grade products. During HVP treatment, cracks/micro-cracks are generated which results in pre-weakening of the treated ore particles, which ultimately results in energy savings in the downstream comminution processes. HVP treatment followed by conventional grinding also results in improved liberation of the valuable minerals in comparison to that achieved with traditional conventional comminution, subsequently improving downstream separation efficiencies. The three major improvements in ore processability through HVP pre-treatment have the potential to facilitate rejection of low grade ore prior to processing, increase production rates, reduce the energy required for comminution and improve flotation separation recoveries. This paper summarizes the major research outcomes of HVP pre-treatment demonstrated using ores from various mining operations conducted by the JKMRC. It also discusses the barriers that must be overcome before it can be adopted by industry with confidence in a continuous high tonnage rate application.INTRODUCTIONThe challenges of declining ore grades and increased plant throughput rates, resulting in higher energy consumption and operational costs, require the mining industry to adopt new technologies to make future ore treatment economically viable. Over the past 50 years, many researchers have engaged in investigating novel comminution techniques. Since Yutkin (1955) first demonstrated the potential to generate shock waves with pressures exceeding 103 MPa via electrical breakdown of water, several applications of electrohydraulic crushing by shock waves have been reported (Curley-Macauly, 1968). Interest in this technique was bolstered when Andres (1977) demonstrated that electrodynamic fragmentation results in superior liberation of mineral grains as compared with conventional grinding techniques. Despite mounting laboratory-scale evidence of the efficacy of electrodynamic fragmentation for mineral liberation, development of the technology for full-scale operation has stalled, primarily because the energy required to achieve desirable mineral liberation is approximately two to three times that of mechanical comminution, amounting to approximately 100 kWh/t for typical mineral ores (Andres et al., 2002)."

Jan 1, 2018

By Hideki Yamamoto, Norihiro Murayama, Junji Shibata

"Hydrothermal syntheses of zeolite from coal fly ash were carried out by using various alkali sources. NaOH, Na2CO3, KOH, K2CO3 and their mixture were applied for an alkali source of zeolite synthesis. The various physical properties of the reaction product, such as the kind of zeolite crystal, cation exchange property, surface texture and so on, was investigated through the zeolitization reaction from fly ash. The mechanism of zeolitization reaction was considered from these results.Zeolite P(NaP), hydroxysodalite(HS) and chabazite(K-CHA) are synthesized as zeolite species, when fly ash hydrothermally reacts in various alkali solutions at 393K. The crystal structure of the products obtained in NaOH solutions for 3h changes from NaP to HS with increasing NaOH concentration. K-CHA formation in KOH solutions needs 10h of reaction time, which is longer than that of NaP or HS.Dissolution, condensation and crystallization steps exist in the zeolitization reaction from fly ash, and the particle surface of products remarkably changes in each step. The fly ash is spherical particles and the surface is smooth(Fig.1(a)). The dissolution of fly ash occurs in the heating process until 393K, and the particle surface changes like unevenness(Fig.1(b)). In case of NaP, the condensation of aluminosilicate ions takes place at 373-393K, and the amorphous aluminosilicate is deposit on the unreacted fly ash(Fig.1(c)). The crystallization of NaP already begins to occur at 393K and the surface is covered with fine zeolite crystals for 24h(Fig.1(d))."

Jan 1, 2003

By C. L. Lin

Previous research on particle damage during high pressure grinding roll (HPGR) crushing was limited by the resolution of point-projection micro CT systems and the extent of damage was described by the percent of particles cracked for different crushing methods as determined at a voxel resolution of 40 microns. With recent advances in X-ray optics, the resolution afforded with point-projection micro CT systems has been improved by at least an order of magnitude using a lens-based X-ray micro CT system. With the use of X-ray lens imaging the resolution is determined by the lens rather than by the spot size of the micro-focus X-ray source. The high resolution X-ray micro CT (HRXMT) system made by Xradia with a voxel resolution of less than 1 micron is now being used for the characterization of particle damage during HPGR crushing. In this way, the direct 3-D determination of the internal damage of crushed ore particles which vary from 40 mm down to 100 microns in size is being studied at a voxel resolution of a few microns. The number, size, and shape of cracks can now be measured at this improved resolution and for the first time the specific crack surface area distributions of the crushed product can be calculated from HRXMT images using specially designed software tools for 3D analysis. Results from selected crushing operations are presented. Copper ore particles from HPGR crushing at high pressure (6 N/mm2) are severely damaged having crack specific surface areas as great as 10 mm2/mm3. Keywords: HPGR, particle damage, X-ray micro tomography, crack surface area

Sep 1, 2012

By Aubrey Mainza, Malcolm S. Powell

"A hydrocyclone with two vortex finders, named the three-product cyclone (3PC), has been successfully tested in the Platinum industry for dealing with the dense Chromite found in UG2 ores. This dense component preferentially reports to the cyclone underflow, resulting in an over-ground fine Chromite component in the final product. The dense media effect caused by a high concentration of this in the cyclone feed produces a coarsening of the cyclone overflow, which results in loss of recovery through over-size silica in the PGM carrying component material in the float feed. The fine barren particles of Chromite that report to the overflow are recovered through entrainment in the flotation process, resulting in detrimental contamination of the slag produced from the concentrate.Data from many industrial scale tests of the 3PC have shown that three distinct products are obtained when the inner vortex finder length (LIVF) is extended to the region either above (normal classification) or below (reverse classification) the transition zone (a region were the inner and outer overflow streams are identical). Due to wear problems arising from extending the IVF deep into the cone of the cyclone, it is advantageous to use the shorter IVF. Only the normal classification results are reported here, but similar outcomes (to opposite overflow streams) were obtained for the reverse classification. The results showed notable differences in the percentage split of the plus 100µm material in the product streams, confirming that three distinct products are discharged from the 3PC. About 12% of the plus 100µm material in the feed reports to the middlings stream, 1% reports to the final product, and the remainder to the cyclone underflow.Results of silica and chrome splits to the three distinct products namely, the inner overflow (INO), the outer overflow (OUO) and the underflow (U/F) are given in Table 1. These show that the 3PC can be used to recover coarse silica through screening the middlings product - which has a high silica content. When the vortex finder ratios (ratio’s of cross-sectional areas) are carefully selected, the split of plus 100µm silica to the middlings product ranged from 2.9 to 9.6%. Large amounts of oversize silica and chrome report to cyclone underflow, explaining their high percentages in the underflow stream."

Jan 1, 2003

By A. Gülmez

The complex ore deposit containing fluorite, barite and bastnaesite minerals is located in Beylikova Region of Sivrihisar town of Eskisehir Province of Turkey. The ore contains 40.80% CaF2; 35.35% BaSO4; 2.01%Ce; 1.5% La; 0.39% Nd and 0.1% Th. Barite recovery from this ore by flotation of the HCl leached tailings is presented in this paper. Rare earths are recovered by leaching. The leached residue (tailings) containing fluorite and barite is subjected to froth flotation to recover barite. The effect of pH and collector concentration on the flotation of barite have been studied in this work.

Sep 1, 2012

By Claudio Bisso, Javier Vargas, Charles Lozano

"This paper summarizes the activities performed to predict SAG milling throughput at Minera Esperanza. Having highly reliable geometallurgical models aided by the new computer tools and specific metallurgical testing to rely on has become a major issue in recent times due to their impact on the business. Minera Esperanza’s SAG throughput model was constructed by characterizing the ore feed and operational parameters of the plant. Producing a robust model required satisfying number of requirements for the parameters used for both the ore and the plant as follow: 1) geologic and geometallurgical characterization parameters; and 2) parameters of a plant running at the rated production under optimum operating conditions. Obtaining these parameters required increasing the quantity of samples and metallurgical testing through drilling campaigns, mapping the drill holes and putting samples through various comminution tests while sampling all operational flows at the plant to obtain the metallurgical information for the operational parameters. The information was entered on the JKSimMet software to enable a throughput model to be developed to output SAG mill throughput predictions that are very close to actual throughput figures, i.e., accurate within a range of 2% on a monthly basis."

Jan 1, 2014

By Sunil Tripathy, Y. Rama, Srinivasulu. A., Amit Ranjan

Process improvements in an operating plant are always challenging. Mineral beneficiation plants based on gravity concentration techniques need continuous evaluation and monitoring of its processes for getting maximum recovery and better grades. But, in an operating plant it is very difficult to control all the parameters due to numerous reasons such as unsteady operation, fluctuation in the quality of run-off-mine ore, overall flow rate etc. For better understanding of the beneficiation circuit, it is necessary to evaluate the critical operating parameters which affect the performance in terms of grade, recovery and throughput including losses of valuable materials into tailing. Accurate data collection and proper data interpretation followed by making necessary change which is implementable in an operating plant play very critical role in performance of the circuit. In case of gravity operated beneficiation circuits of chrome ores where the quality of the feed and physical parameters varies continuously, the operators are required to modify the critical operating process parameters on continuous basis which is very difficult and tiresome. There are many causes of the data variability, including both error (sampling and assay), and real variation in performance due to changes in ore mineralogy, operating conditions and other factors. In this article, attempts made to evaluate the performance of ultra-fine beneficiation circuit in terms of silica reduction in the concentrate of chrome ore beneficiation plant (COB), India are discussed. The approach adopted and practical problems encountered during the study were also discussed. Results obtained from plant audit based on the above methodology has shown that SiO2 content in the concentrate can be reduced to <4%.

Jan 1, 2014

By M. V. S. Cavalcante

The quality of iron ore pellets, represented in terms of parameters such as cold compressive strength (CCS) and Tumble Index (TI), has a strongly influence on the productivity and energy of reduction furnaces like the blast furnace and on the quality of hot metal or liquid iron. The main objective of pelletization operations is to produce iron ore pellets of desirable specifications and ensure high levels of plant productivity and energy efficiency. Advanced process control of an industrial iron ore pellet induration process using a soft sensor for pellet quality and fuzzy-logic based control algorithm is described in this paper. The pellet quality soft sensor consists of a rigorous mathematical model of the induration process and a statistical model for the pellet quality parameters. The mathematical model is based on the fundamental principles of heat and mass transfer between gases and pellets, kinetics of drying and condensation of moisture, combustion of coke, calcination of limestone, and melting and solidification of pellets. The predictions of wind-box temperature profiles are in close agreement with the measured profiles. The time-temperature profiles of the pellets during induration, along with raw material characteristics and induration process operating conditions, are used as inputs to the quality model to predict cold compressive strength and the Tumble Index. The predictions of the quality soft sensor along with the rules based on fuzzy-logic derived from simulation results and operator experience are then utilized to control the induration process to achieve precise control of the quality parameters and to optimize the induration process in terms of fuel efficiency and productivity. The mathematical model is also utilized as a soft sensor for temperature, moisture and composition profiles of pellets and gases. Results of implementation of this model-based control strategy on an industrial scale induration process will be presented. Keywords: iron ore, pelletization, simulation, process control, optimisation

Sep 1, 2012

By F. K. Ikumapayi

An approach to environmental sustainability and improved process economy, in sulphide minerals production is recycling of process water in flotation of complex sulphide ores, although the chemistry of process water may be a critical issue to flotation efficiency. The influence of major components of calcium and sulphate ions in process water on xanthate collector adsorption and flotation response using pure chalcopyrite, galena and sphalerite minerals were investigated by Hallimond flotation, zeta-potential measurement, FTIR and XPS spectroscopy studies, while bench scale flotation tests were also carried out using complex sulphide ores. The impact of the species in flotation was comprehended using deionised water, tap water, process water and simulated water containing equivalent amount of calcium and sulphate species in process water. Hallimond flotation results showed a decrease of chalcopyrite and galena recovery in process water and also in the presence of calcium and sulphate ions in both deionised and process waters, whereas sphalerite does not respond to flotation. The adsorption of calcium and metal ions but not sulphate ions on the minerals is evidenced by zeta-potential data. FTIR and XPS studies revealed the presence of surface oxidized sulfoxy species and surface calcium carbonates on chalcopyrite in the presence of process water and water containing calcium ions, surface oxidized sulfoxy and carbonate species on galena in the presence of deionised water, process water and water containing calcium and sulphate ions, all at flotation pH 10.5, and these surface species influenced xanthate adsorption. The presence of surface oxidized sulfoxy and carbonate species at the sphalerite flotation pH 11.5 were seen in the presence of deionised water, process water and water containing calcium and sulphate ions, but the surface species does not influence xanthate adsorption. Bench scale flotation using two different complex sulphide ores showed that chalcopyrite, galena and sphalerite recoveries are better in process water than tap water. The studies showed that the process water can be recycled in flotation with no detrimental effect on grade and recovery of sulphide minerals. Keywords: sulphide minerals, flotation, zeta-potential, FTIR, XPS

Sep 1, 2012

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

By Kaioeng Wang, Qi Liu, Yahui Xiang

"In the differential metal sulfide ore flotation it is desirable to replace the toxic inorganic depressants with environmentally benign chemicals. Chitosan, as a natural and non-toxic polymer, has been proven to be an efficient depressant for chalcopyrite while allowing galena to be floated by xanthate collectors. However, the poor solubility of chitosan limits its potential applications as the flotation could only be carried out at about pH 4 where chitosan is soluble. A carboxymethyl derivative of chitosan, named N-carboxymethyl chitosan (N-CMC), was synthesized by substituting the amino groups of chitosan with carboxymethyl groups. The substitution significantly improved the solubility of chitosan. The structure of N-CMC was studied and compared with chitosan via Fourier transform infrared spectroscopy (FTIR). Flotation tests were performed on single minerals and mineral mixtures (with weight ratio of 1:1) with the addition of appropriate amount of potassium ethyl xanthate (KEX) and N-CMC. The solution pH was varied from neutral to alkaline. The flotation concentrates and tailings were collected and analysed for the contents of copper and lead. FTIR measurements showed that new peaks of C=O stretching of -COOH and N-H deformation of -NH- appeared in N-CMC, which indicated that the carboxymethyl groups were introduced and the amino groups were the sites for the substitution. Flotation results indicated that N-CMC could depress either chalcopyrite or galena depending on the pH. The results were not affected by the sequence of KEX and N-CMC addition. Therefore, N-CMC is potentially useful in Cu-Pb sulfide separation following a bulk Cu-Pb flotation. The N-CMC was also found to have surface cleaning functions, and was able to remove contaminating copper ions from galena surfaces. Therefore, its application in sulfide ore flotation is expected to be more robust than the original chitosan."

Jan 1, 2014

By A. T. Sutaone

"Battery grade Mn ore is not found in India except in Dongri-Buzurg Mine, Dist. Bhandara, Maharashtra. The mine located in central India is operated by a premier company viz. Manganese Ore India Ltd., under Central Government Public Sector Undertaking. The company is not selling the product as battery grade material but instead primarily catering to the needs of the iron and steel industry in the country. However, a part of the ore is being used in-house for the production of electrolytic manganese-dioxide in their EMD plant, which is located near the mine.The production of lumpy ore for steel industries generated through multi-stage crushing and screening has resulted in accumulation of about 50,000 tonnes of low grade fines over the year, which contain low of Mn values. Further, the generation of fines is still on going process due to the production of lumpy ores. These fines are stacked in the form of unconsolidated dumps, which create environmental problems like air and water pollution and siltation in the adjoining fields. Besides they are occupying large space, which is scarce in this mining area. The Indian Bureau of Mines under one of its statutory functions has suggested the company to explore the possibility of recovery of additional values under conservation and environmental aspects. Hence the company has sponsored a bulk sample for beneficiation studies in the Modern Mineral Processing Laboratory and Pilot Plant of Indian Bureau of Mines at Nagpur, India. The main manganese minerals present in these mine rejects have been identified as pyrolusite and psilomelane. The purpose of this study was to explore the possibility of evolving a suitable beneficiation flowsheet to obtain manganese concentrates assaying over 72% MnO2 to be used as raw material for the manufacturing of dry cell batteries."

Jan 1, 2003

By Marianella Perez, Williams Calderón, Gonzalo Montes-Atenas

The lack of fresh water sources, particularly in the Northern part of Chile, has driven the mine sites to search for new and sustainable paths to obtain water resources to run minerals processing operations. Among them, the use of seawater in concentrators appears as an interesting solution to this problem. However, the presence of seawater will have an impact onto the operation, not only because it will enhance corrosion reactions in the equipment installed in a plant, but also because it may affect how particles will effectively be processed across the numerous unit operations existing in the mine site. Among such unit operations, the grinding stage is a highly regarded as it defines the success of the separation of valuable minerals from gangue material in the froth flotation operation. Then, one important aspect to be addressed is to understand how the presence of seawater will affect the different mechanisms acting during the operation of a ball mill. The aim of this research work is to assess the effect of changing the aqueous matrix from process water to seawater in ball mills onto the mill performance. The methodology considered the use of Fluent® software and its capabilities to run numerical simulations with heterogeneous media. On one hand, from the data analysis, it is possible to infer that breakability mechanisms should not be significantly affected. On the other hand, the high ionic strength of the matrix should impact importantly particle transport mechanisms within the mill. Particularly, when transporting finer particles. Rheology results were in agreement with previous published research studies suggesting the suspensions to behave as Newtonian, Dilatant o Pseudo-plastic fluid depending on the amount of fine particles present in the grinding media. The latter will result in changes in the residence time of particles in the mill producing overgrinding or an excess in the circulating loads.

Jan 1, 2014

By F. O. Milovich, V. A. Ignatkina, L. A. Samatova, E. D. Shepeta

"The aim of the research was to increase technological parameters of the flotation of finely disseminated scheelitecarbonate ore using selective reagent regime.In the studies the monomineral fractions of scheelite and calcite; samples of the scheelite-carbonate ore of the Primorsky deposit with the range of the carbonate module 3-65 were used. A carbonate module of ore is the ratio an initial assay of calcite to an initial assay of scheelite. Sodium oleate, iso-decyl alcohol, water glass, calcium chloride, soda or sodium hydroxide as flotation reagents were used. The flotation method in the Hallimond tube and in a mechanical cell, an adsorption method for study the kinetics of adsorption of oleate and isodecyl alcohol and its combinations on scheelite and calcite, IR spectroscopy including ATR to study the composition of surfacecompounds were applied. Selective reagent regime may include two ways - a combination of collectors or a modification of depressants of calcite and other gangue minerals. On one hand the combination of sodium oleate and higher fatty iso-alcohols of fractions C12-C16 in the rough scheelite flotation to reduce the flotation activity of calcite has been studied. On the other hand depression of calcite flotation by calcium chloride with water glass into rough flotation was used; modified the steaming cycle by Petrov's method applying change the concentration of water glass and other. Fatty iso-alcohols can adsorb on the surface of the calcite that reducing the adsorption of sodium oleate and floatability of calcite has been fallen. Their co-adsorbing with oleat on the scheelite surface were support the hydrophobization and flocculation of slime particles of scheelite. Flocculation of the particles of scheelite leads to increased up 3 times of the recovery of scheelite from the slime class, and calcite change up only 1.4-1.1 times it’s recovery.The growth of the carbonate module more than 11 is decreased the assay of WO3 in the scheelite concentrate of selection cycle."

Jan 1, 2018

By J. Shibata

The behavior in electric field of fine particles present in aqueous solution was measured in order to apply to the classification of fine particles. The sample particles used are spherical polystyrene particles with the average diameter of 0.03 µm, 0.1 µm, 1.0 µm, 4.3 µm and 9.6 µm. Electrophoretic mobility and zeta potential of various particles are measured by an instrument based on the principle of the laser Doppler effect. The influence of temperature, electrolyte concentration on the electro-phoretic mobility was investigated for various polystyrene particles. The electrophoretic mobility increases with increasing pH and temperature of suspensions. The measured electrophoretic mobilities are different from electrolyte concentration and particle size. The electrophoretic retardation effect and relaxation effect are considered to explain the behavior of fine particles in electric field by applying the electro kinetic theory of Wiersema et al. For all particle size, the electrophoretic mobility decreases rapidly in high concentration of KNO3 such as 0.1 mol/dm3due to the compression of electric double layer The forces acting the particles in electric field are considered to be electrical force, friction force and some other forces like relaxation effect and electrophoretic retardation effect which appear in ionic behavior. It is considered that the particle moving velocity depends on the particle size. When the particle size is less than 1µm, the velocity increases with increasing the particle size. On the oth-er hand, the velocity deceases with increasing in particle size, when the particle size is larger than 1µm. This phenomenon is considered to be interesting from the viewpoint of classification for fine particles. We found that the electrophoretic mobility of 1.0µm particles is larger than that of 0.1µm particles, and that it is possible to classify fine particles by using the difference of electrophoretic mobility by many experimental results. The phenomena can be explained by the forces acting the fine particles in the electric field. We can apply the behavior to classification of fine particles.

Jan 1, 2014

By Vladimir G. Kochnev

An innovative AG and SAG technology aimed to be applied in grinding of ores and in the production of construction materials is described. A novel design of a cantilever-type mill capable to operate in autogenous, semi-autogenous and ball grinding mode ensures easy delivery and installation even in remote areas, and low capital and operating costs. Results of the tests of the new heel-shaped liners performed by TTD jointly with ALROSA, MINTEK and Anglo-American Corporation are reported. The approach includes also a novel discharge grid design and a technique of treating the material of critical size. These innovations make grinding in AG and SAG mills dramatically more effective, with an increase in the throughput rate and a reduction in power consumption ranging from 1.5 to 2 times.

Jan 1, 2003