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By Reza M. Rahman

The froth phase plays an important role in the flotation and upgrading of the final concentrate. At present, the techniques that have been used in the mineral industry to measure the froth recovery have limitations. The aim of this paper is to investigate the performance of the froth in an industrial flotation cell. A unique device has been developed which is capable of decoupling the froth zone from the pulp zone. It consists of two concentric tubes. The inner tube acts as a dropback collection chamber or catcher. The particles that detach from the froth phase fall directly into the catcher and are collected as froth dropback. The froth recovery measurements were carried out in a rougher bank of a copper concentrator treating sulphide minerals. The dropback device is designed so that it can be immersed into a plant size flotation cell and plant froth recovery measurements can be taken at any given time. During the experiments, the bubbles laden with valuable mineral particles entered the device from the plant flotation cell, subsequently rising to form a froth layer at the top of the device. The particles that detached from the froth zone were collected in the dropback collection chamber whereas the concentrate sample was collected by a launder. By drying, sizing and chemical analysis of the concentrate and dropback samples, the froth recovery, was estimated on the basis of the valuable component. The effect of air rate on froth recovery was also investigated. Keywords: flotation, froth, dropback, froth recovery

Sep 1, 2012

By Daniel Saramak

"Issues concerning effectiveness of the high-pressure comminution process in technological circuits of copper ore treatment were presented in the paper. Crushing processes taking place in high-pressure grinding rolls devices (HPGR) are currently one of the most efficient methods of hard ore size reduction in terms of the energy consumption. The HPGR products are characterized by a fine particle size and the micro-cracks formation in individual particles, which appear in downstream grinding processes, decreasing their energy consumption. The purpose of this paper was to analyse the effectiveness of a ball mill grinding process depending on the changeable conditions of run for the HPGR crushing process. The research programme carried out included crushing tests in the laboratory scale HPGR device at various settings of the operating pressure volume and selected qualitative properties of the feed material (i.e. particle size distribution). Particle size distribution analyses of all HPGR products were performed and in the next stage the material was a feed to the ball mill grinding process. Grinding process kinetics were investigated through the determination of mass recoveries of individual particle size fractions after defined grinding time intervals. The models, defining the grinding process effectiveness as a function of changeable conditions of HPGR process run, were determined on the basis of obtained results. Based on these models the optimal grinding time in a ball mill was specified which is, in turn, the basis for optimization of operation of the technological comminution circuits for a given material type. The obtained results proved that the application of HPGR devices in a given copper ore comminution circuit may improve the effectiveness of the downstream grinding process which leads to improvement of the entire circuit work efficiency through decreasing the process energy consumption and enhancing product size reduction."

Jan 1, 2014

By Partha Patra

Numerous proteins of varying properties are available in extracellular bacterial proteins (EBP) isolated from Paenibacillus polymyxa. EBP was fractionated through ammonium sulfate precipitation in a controlled fashion and characterized through SDS-PAGE technique. Different groups of proteins, (Group A~D) exhibited varying degrees of surface affinity to minerals such as quartz, pyrite, chalcopyrite, galena and sphalerite. Interaction with mineral specific bioproteins rendered pyrite and chalcopyrite hydrophilic while surface of quartz, galena and sphalerite turned more hydro-phobic. Specific groups of proteins could thus be used for selective separation of galena, sphalerite and quartz from pyrite and chalcopyrite (as a mixed sulfide) through microbially-induced flotation or selective flocculation.

Jan 1, 2014

By Kirsten Corin, Margreth Tadie, Michael Nicol, Cyril O’Connor, Jenny Wiese

"The recovery of base metal sulfides has been emphasized in the study of the flotation of platinum group minerals (PGMs). However, in some ore bodies such as the Platreef of the Bushveld Complex, sulfide minerals do not make up the majority of the more significant PGM mineralization. It is therefore important to develop a fundamental understanding of how non-sulfide and sulfide PGMs respond respectively to the current reagents being used in the flotation of these minerals. The interactions between platinum and palladium sulfides and tellurides with the thiol collectors, ethyl xanthate and diethyl dithiophosphate, have been studied using the electrochemical techniques of mineral rest potential and voltammetry measurements. The differences in the interaction between the two types of minerals with these reagents were of key interest. Rest potential measurements indicated stronger electrochemical interactions of the minerals with ethyl xanthate than diethyl dithiophosphate. These measurements also indicated that there are different forms of oxidized collector present on the mineral surfaces after interaction with ethyl xanthates. Voltammetry measurements support these observations and suggest differences of adsorption on Pt and Pd sulfides than on Pt and Pd tellurides. Voltammetry also showed that there was minimal electrochemical interaction between the Pt and Pd minerals and diethyl dithiophosphate."

Jan 1, 2014

Mineral flotation is effective over a relatively narrow particle size range of approximately 10 µm to 150 µm. If the upper particle size limit can be increased, however, a run-of-mine ore may be coarse ground, and only the middlings are ground further to achieve required grades. This will result in significant energy savings and increased throughput. In this communication, methods of increasing the upper particle size limit will be discussed on the basis of a flotation model that can predict flotation from both hydrodynamic and surface chemical parameters. An example of increasing flotation recovery by control of a chemistry parameter is given.

Jan 1, 2014

By H. Gallardo, J. Yianatos

Flotation is a separation process in which mineral recovery depends on the particle surface properties. The selective collection of particles by air bubbles requires hydrophobic mineral surfaces. Hydrophobicity can be selectively induced on a valuable mineral surface by means of reagents. For this purpose, it is required that mineral grains in the ore become physically liberated or exposed in the particle surface after grinding. The grinding process generates three types of particles according their exposed surface in the floatable mineral: locked particles (0-10%), associated particles (10-90%) and liberated particles (90-100%). Locked particles have low floatability, and they typically show low recovery (<20%), while liberated particles have a high floatability and can be easily recovered (98-100%) at different particle sizes (10-150 µm). The main challenge in the flotation process is the recovery of associated particles. These particles typically have recoveries of 20-80%, but strongly depend on the particle size, particle surface liberation and collector dosage. Recent studies on particle floatability by size-liberation have significantly contributed to improving the characterization of flotation processes. In this work, a study of flotation recovery of associated particles of 10-90% liberation is presented for particle sizes (10-150 µm) and collector dosages (5-40 g/ton). In this work historical data on galena recovery based on particle cross-section composition of galena was used, assuming they represent an acceptable estimate of particle surface composition, as shown by some previous researchers. The results showed that galena recovery can be well represented by a model consisting of the interaction of a linear function and a Gamma distribution function to account for the liberation and the particle size effects. Consequently, an alternative approach for modelling the recovery of associated mineral (10-90% liberation), with a reduced number of parameters, was developed and validated.

Jan 1, 2018

By G. I. Voiloshnikov, V. E. Dementyev

"One of the most important advances in the world gold metallurgy is the introduction of adsorption technologies for processing of ores and concentrates. «Adsorbent-In-Pulp» process allows to eliminate pulp filtration that is especially important during processing of clay and slime bearing ores. “Adsorbent-In-Leach” process is one of the ways for processing of preg-robbing (carbonaceous) products. High efficiency, increased metals recovery, decrease in capital and operational costs, possibility of easy control and adjustment are the advantages of adsorption processes. Anion-exchange resins and activated carbons are used as adsorbents. This paper presents Irgiredmet experience on gold adsorption technology using both adsorbents (RIP, RIL, CIP, CIL processes). It includes results of long-term studies of different theoretical and practical issues of adsorption processes. Irgiredmet started development of ion exchange technology (RIP, RIL) in 1964. Laboratory and pilot plant tests were conducted to develop process design criteria for 15 RIP plants of the former USSR. During this test work a great number of newly synthesized resins including strong- and medium-base resins was studied, different types of adsorption feed (ores and concentrates) were tested; some theoretical regularities of adsorption process were investigated; the technology of two stage adsorption for silver gold ore, improved flowsheet for gold elution and resin regeneration, designs of technological equipment for adsorption, elution, electrowinning processes including pulsation columns, electrowinning cells etc. were developed. Irgiredmet took part in commissioning of practically all RIP plants in the former USSR. Due to its efforts RIP process became to be the standard technology. Last Irgiredmet RIP projects include the development of adsorption technology using medium-base resin for the three mines owned by GC Petropavlovsk (Amur region, Russia). The complex of the testworks on activated carbon gold adsorption technology including the search of prospective activated carbons; study on gold adsorption mechanism; development, testing and introduction of process flowsheets and the equipment for their realization was conducted. The original gold elution process was developed. The developed CIP technology was firstly introduced at Lebedinsky gold plant (Yakutia). Now carbon adsorption technology is widely used at Russian gold mines as CIP, CIL, CIC processes. The most relevant example of CIP introduction is Svetlinsky gold plant (Ural, Russia) with capacity 8 Mt of ore/ year."

Jan 1, 2018

By A. Mainza, H. Hill, L. Bbosa

"The main objective of ore breakage characterization is to quantify the relationship between the energy supplied for breakage and the size of the resultant progeny. In this study, the ore breakage characteristics of drill core particles and crushed particles were compared. Single impact breakage tests were conducted on a basalt ore sample using the JK rotary breakage tester. The size-dependent model by Shi and Kojovic was used to fit the breakage data because the effect of initial particle size is accounted for in the model. It was found that crushed particles consistently gave a higher degree of brokenness than drill core particles and the differences were attributed to the internal structure of the particle. Drill core particles contain a lower crack density (paths of weakness) than crushed particles which have been pre-weakened during the crushing process. An increase in crack density is directly related to a decrease in the minimum threshold energy. Upon application of a stressing force above the stress threshold, particles with a higher crack density will fracture more easily because of a higher rate of crack propagation due the numerous paths of weakness available. It was therefore concluded that under the same conditions, drill core particles are more competent than crushed particles. INTRODUCTION Comminution devices have commonly been reported as being the largest energy consumers in mineral processing circuits (Napier-Munn, 2015). Cleary (1998) reported that the inefficiency of comminution devices is a result of less than 5% of the supplied energy being utilized for breakage, with the majority being expended as heat and noise. With steadily declining fossil fuel supplies and a looming global energy crisis, the mineral processing industry has increased its focus on energy reduction measures. Ore breakage characterization plays a critical role in the design and optimization of comminution circuits (Tavares and King, 1998). The main objective of ore breakage characterization is to empirically quantify the relationship between the energy supplied for breakage (specific input energy) and the size of the resultant progeny through laboratory particle breakage tests (Napier-Munn, 1996). Commonly used laboratory breakage devices include the Drop Weight Tester (DWT), Split Hopkinson Pressure Bar (SHPB) and more recently, the JK Rotary Breakage Tester (JKRBT). Typically, a standard single impact breakage test procedure consists of a matrix of experiments on particles in four to five narrow size fractions each tested at low, medium and high energy levels. The resultant progeny of each test is sized to obtain a particle size distribution (PSD) from which the degree of breakage, usually in the form of a t10 value (percentage of the progeny material that passes 1/10 of the feed size) can be obtained for each size fraction and energy level (Napier-Munn, 1996)."

Jan 1, 2018

By M. Niinae

Electrokinetic soil remediation by electroosmosis and ionic migration is restricted to soluble sub-stances. At a higher pH, the soil particles sorb more heavy metals, such as cadmium, than at a lower pH and the precipitation reactions of heavy metals are promoted. Both mechanisms make heavy metals immobile, rendering clean up more difficult and electrokinetic extraction inefficient. There-fore, the acidification of soils is very important to increase the clean up efficiencies of heavy metals, such as cadmium by electrokinetic method from contaminated soils. In the present study, acidification of soils and cadmium transport are predicted with a numerical method in which electrical flow is coupled with hydraulic flow, and the sorption process in the soils is induced in the model. The effects of some factors such as electrode configuration, electric field strength and electrode spacing for saturated soils are investigated using this numerical model. The results obtained this study are summarized as follows: The two-dimensional electrode configurations containing cathode surrounded by three or more anodes rapidly acidify the soils and remove cadmium from soils compared with one-dimensional electrode configuration. However, two-dimensional electrode configurations develop spots of inactive electric field between cathodes. A larger electrode spacing increases the processing time required, and it was also found that a larger electric field strength reduced the processing time required.

Jan 1, 2014

By Y. Q. He

The methodology of active pulsing air separation is a new method for dry material classification. Especially, it is suitable to electronic scraps disposal and re-utilization. By studying the difference of drag coefficients of the particles moving through areas of varying Reynolds numbers, and considering the extra-mass forces acting on the particles in the active pulsing air field, models of the dynamic motion which particles follow were developed. A computer simulation was prepared that showed the traces of particles with different densities and/or diameters, but similar aerodynamic characteristics, as they moved through the turbulent flow, to modify and define the parameters of the models. The simulation was found to predict the observed results with artificial tracing spheres being separated by the laboratory equipment. The separation performance, as being affected by the particles, nature, the air velocity, the pulsing frequency and the air pattern, is discussed. In general, lower density particles are more responsive to variations in airflow velocity. In addition, an industrial scale active pulsing air separator was designed, and it provides a new and efficient method for resource re-utilization in China.

Jan 1, 2014

By J. Drzymala

Ores and raw materials are subjected to mineral processing operations to increase the content of their useful components. Upgrading of these materials can proceed with different selectivity and therefore, there is a need to know and monitor the separation results of the process. The separation results can be evaluated using tables and graphs called upgrading curves. The course of lines in the upgrading curves is usually complex and depends on the graph type and process parameters. The Halbich grade vs. recovery plot is frequently used because is practical and it indicates several characteristic features of separation results. Separations by means of flotation of several different shale, dolomite and sandstone copper ores were performed along with determination of their mineral composition, copper content, liberation degree, and the maximum theoretical copper content in the first concentrate. These data, plotted as the Halbich upgrading curves, allowed to find other characteristic points such as practical maximum copper content in the first concentrate, maximum curvature coexisting with the liberation degree, maximum recovery of ore valuable components, and the slope the recovery-grade line at high recoveries as a measure of liberation. Correlations between theoretical and practical maximum copper contents in the first concentrate as well liberation degree and maximum curvature were also presented. They show that the ore type significantly influences the shape of the Halbich curve and its characteristic points.

Sep 1, 2012

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 Klaus M. Hahn, Kurt Aasly, Jutta Lennartz, Hermann Wotruba, Ben Snook, Przemyslaw B. Kowalczuk, Rolf Arne Kleiv

"Seafloor massive sulphide (SMS) deposits have been identified as important marine metal resources for the future. However, literature on mineral processing of SMS is currently limited, and to date, no research has been published on processing of SMS from either active or inactive hydrothermal vent fields on the Arctic Mid-Ocean Ridge. In this paper, individual SMS rock samples from the Loki’s Castle area were tested. Chalcopyrite, isocubanite and sphalerite represented the main copper and zinc bearing minerals in the SMS samples, whereas the gangue consisted of barite and silica. Based on the X-ray transmission response (XRT), i.e. differences in the atomic number of elements in tested samples, and using portable XRF (PXRF) values of elemental composition, individual particles were classified as a either product (low barium / high to low silicon / high copper and zinc) or waste (high barium / high silicon / low copper and zinc). The classification was based on the elemental composition of the samples with the cut-off grade equal to 0.5% for copper. It was shown that the XRT discrimination analysis correlated well with elemental (PXRF) data classification. The results clearly indicate that X-ray transmission sensor-based sorting can be used a useful technique for preconcentration of SMS rock samples. INTRODUCTION Due to different compositions of investigated samples, sensor-based sorting is a useful technique for preconcentration of different materials. The aim of using sensor-based sorting is to upgrade an ore by reducing the quantity of overall waste material reporting to the next processing stage. This can be achieved by eliminating (reducing) the waste fraction. By applying sensor-based sorting, the energy consumption for particle comminution as well as the required process water and reagents can be decreased. The total volume of the waste rejection leads to a proportional reduction in the total energy costs (Lessard et al., 2014, 2016)."

Jan 1, 2018

By S. K. Chaurasiya

o meet the ever increasing demand of iron oxide feed stock for rapidly growing domestic steel industries and to effectively manage the depleting reserve of high grade lumpy iron ore, Pelletization of iron ore fines/slimes are expected to play a dominant role in the near future. Use of pellets will also enable the blast furnace operator to achieve higher levels of productivity with lowering of operating cost. The effective utilization of Iron Ore Slimes is important not only from the point of view of optimum utilization of Iron values in the mined ore but also for preventing environmental pollution. A significant amount of slime is being accumulated at the tailing dam of one of the iron ore mines and with the present scale of operation the tailing dam will be filled in another 10 years. Hence to increase the life of tailing dam and for better utilization of the iron values a study has been carried out for the suitability of pellet manufacturing with slimes and fines at our laboratory. The pelletization studies are aimed for optimization of various parameters for production of Blast furnace/ DR grade pellets from beneficiated slimes and Fines. This paper attempts to describe the production of blast furnace grade pellets from beneficiated slime and fines and its characterizations.

Sep 1, 2012

By Dilip. Makhija, Asim. K. Mukherjee, Tamal Ghosh, Abhay Patra

In India around 15-20% of Run of Mine (ROM) from any iron ore deposit reports to slime dams as byproduct of iron ore beneficiation process. The proportion of iron ore slime to ROM will increase in future with higher proportion of lean grade ores in ROM. Furthermore, tonnages of iron ore slime will also increase with increasing demand of iron concentrate. Presently, this slime is stored in the dam in the absence of beneficiation technology. A beneficiation flowsheet has been developed at Tata Steel. This process produced concentrate of 2.2% alumina with 40 % yield from slime of 7-9% alumina. The iron content in the reject will be less than 40% thus adhering to the regulatory norm. Pilot scale study show waste from slime beneficiation is a good raw material for making a variety of building materials. Waste from slime beneficiation also has soil amendment properties. Pilot scale studies show productivity of rice increased when the waste of slime beneficiation process is mixed with soil. On commercialization of this zero waste technology slime generated from the iron ore washing plant will be completely used. In this paper the result of the pilot scale studies on slime beneficiation and utilization processes towards soil making and making of building materials are discussed in detail.

Jan 1, 2014

By A. Mainza, I. Govender, J. Waters

"The study of the properties of mineral processing suspensions is important in understanding how a circuit might behave. As soon as the predominantly dry ore enters a wet milling stage the ore properties undergo changes as a ‘slurry’ is created. Slurries can be classified in terms of their physical properties (particle density, solids concentration, particle size and size distribution, particle shape), and their flow properties such as rheology. Slurry flow regimes are classified into true homogeneous, pseudo homogeneous, heterogeneous and fully segregated, and only true homogeneous and pseudo homogeneous suspensions can be characterized by their flow structure. A class of the heterogeneous regime are the so-called dense phase or settling slurries - those which result in a clear water surface on standing, although they may approach a pseudo homogeneous state if suspended for a sufficient period of time. They are usually extremely difficult to characterize by their rheological properties alone and the rheological characterization of these slurries has always posed a problem, especially at higher concentrations. Previous rheological studies have focused on the individual concentrator units dealing with milling, classification, pumping, flotation, fine grinding, thickening.In this work an attempt was made to characterize two ore types (copper and a Platreef platinum ore) using a custom built Paterson and Cooke tube rheometer, at concentrations up to 43% by volume. After applying a turbulence correction, results showed Bingham plastic behavior. A conventional vane rheometer was then used to compare the rheological behavior of platinum concentrator streams. A size criteria was used to identify any rheologically dominant streams."

Jan 1, 2014

By S. Castro, L. Uribe

Seawater can be considered as a particular process water with a high concentration of NaCl (about 0.5- 0.6 mole/L) and high concentration of hydrolyzing metal cations (mainly, Mg2+ and Ca2+ ions). Micro-flotation tests, induction time measurements, and zeta potential measurements have been used to investigate the effect of these ions on the natural floatability of molybdenite. The results demonstrate that molybdenite is strongly depressed in the alkaline pH range over which hydrolysis products of Mg2+ and Ca2+ ions are formed. At pH 10, colloidal magnesium hydroxide seems to be responsible for molybdenite depression in seawater and in Mg2+ solutions. This is also supported by the measurements of the effect of Mg2+ ions on the zeta potential of molybdenite. The mechanism of depression of molybdenite with Ca2+ ions is different, and depression takes place in the pH range were Ca(OH)+ complexes are formed, below the pH of precipitation of calcium hydroxide. Adsorption of the cationic hydroxy species and/or hetero-coagulation of the positive charged colloidal hydroxide on the negative charged molybdenite particles seem to be the main mechanisms involved.

Jan 1, 2014

By G. Semenchenko

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

Sep 1, 2012

By I. Gombköto

Mining and mineral processing operations are usually generating huge amount of tailings. These tailings often gives lots of maintenance work in order to protect environmental resources from heavy metals slowly leaching out of tailing are due to Acid Rock Drainage (ARD) process. Handling leakage could be active or passive such as using of Permeable Reactive Barriers (PRB). PRB?s are used worldwide treating underground contaminations, using different type of matrix materials. All generally used matrix material has its advantages and disadvantages such as selectivity, sensitivity of precipitation generation or not satisfying hydraulic conductivity. Nowadays cheap and effective matrix material which is ignorant to pore plugging caused by precipitation within the PRB could be one solution to the demands of the industry. The authors have been carried out an investigation at University of Miskolc on lignite as high humid acid containing material for determining the ability of heavy metal adsorption and pore plugging resistance. Moreover, using hydraulic and chemical simulation methods, complete PRB dimensioning protocol based on new lignite matrix had been introduced. Within the frame of this paper the results are going to be discussed.

Sep 1, 2012

By F. Bello, J. Engels

"During 2012 and 2013, Minera Esperanza conducted a series of thickening and deposition trials to identify design and operational parameters associated with increased thickening of its tailings. These trials focused on benchmarking the current solids concentration of tailings (62 - 64%) in anticipation of an increase to 67% solids once two new 45 m diameter deep-cone paste thickeners are commissioned in 2014. These trials studied the sedimentation and rheological characteristics of the existing tailings and performed deposition modelling to assist with developing short- and long-term designs for the tailings storage facility. To verify and optimise these models, Minera Esperanza considered a series of laboratory, pilot, and industrial-scale deposition trials. This paper provides a review of the trials conducted in the laboratory and at industrial-scale and considers the results and optimisations for the short- and long-term design of Minera Esperanza’s tailings storage facility."

Jan 1, 2014