Search Documents

By Markus Dammers, Christopher Robben, Hermann Wotruba, Christian Schropp

"In most underground mining processes the entire extracted ore is transported from underground workings to surface processing plants for separation of valuable minerals and gangue material. Most of the transported material consists of barren rock with negligible metal content, especially for low grade deposits, such as in the copper or gold metal ore mining. Increasing mining depths result in higher costs for transportation and hoisting. Therefore, rejecting waste rock as soon as possible from the material stream gains importance. The concept of resource to product integration in the form of earliest waste rejection in combination with subsequent backfilling follows the philosophy of ‚leaving waste underground?. Implementing mineral processing underground can lead to less required mass movement to surface, hence reducing transportation and hoisting costs. At the same time, rejected waste can be used as backfill to increase extraction rates by reducing pillar volumes. In the mill, a stable high grade feed leads to decreased specific operating and investment costs as well as increased productivity and recovery. These effects as a whole have a large potential to reduce cut-off grades so that resources can be turned into reserves. Within the I²Mine (Innovative Technologies and Concepts for the Intelligent Deep Mine of the Future) project of the European FP7, investigations are carried out by the Unit of Mineral Processing of RWTH Aachen University, the Institute of Mining Engineering I and TOMRA Sorting Solutions | Mining. One aim of the cooperation is to develop new concepts for a comprehensive integration of near-to-face processing in combination with backfill into the overall underground mining process. Effects on up-, down- and side-streams are investigated to prove the potential of resource to product integration in comparison to common underground mining systems and processing methods."

Jan 1, 2014

By N. Vasumathi

Most of the Iron ore washing plants set up in India in the earlier days consist of sizing of the ore by dry / wet screening, washing and classification by screw classifiers. In this classical approach, iron values were lost in the form of fines and ultrafine into the tailing ponds as they had little commercial value in those days and accumulated in huge quantities over the years. As the high grade deposits are getting exhausted and the demand for high grade finer material for pellet making is ever increasing, focus is shifting towards recovering the values from the erstwhile tailing ponds by column flotation. This is also supposed to mitigate to a certain extent the environmental problems caused by the ever expanding and unmanageable tailing dams. A case study is presented wherein a composite sample is prepared from samples drawn systematically from multi - locations in a sprawling tailing dam. Laboratory scale column flotation tests on this composite tailings sample, basically originating from two operating iron ore beneficiation plants of JSW Steel Ltd., one of the leading producers of steel in India are found to be encouraging. Desliming followed by reverse and cationic flotation tests using flotation column resulted in the concentrate of 61.88% Fe, 4.81% SiO2, 2.52% Al2O3 and 3.30% loss on ignition (LOI) from the tailings analyzing 57.86% Fe, 7.10% SiO2, 3.52% Al2O3 and 6.14% LOI with 52% weight recovery. The causes for the quality improvement could be attributed to desliming of un-liberated ultra fines of kaoline and hydrated iron oxides and their further reduction by efficient flotation process. The process and the cationic collector developed for this purpose are adopted in the new flotation plant created to treat these tailings. Keywords: iron ore, washing, ultra fines, tailings pond, column flotation

Sep 1, 2012

By Ranjeet K. Singh

Kelsey Centrifugal Jig was found to be promising for the beneficiation of fine coal particles. The present study was aimed at in-depth understanding of the separation features of Kelsey Jig through detailed experimentation. Beneficiation of fine coal of size 150 x 300 µm was studied in a laboratory Kelsey Jig. The thickness of the ragging bed is found to be an extremely crucial parameter apart from the other process parameters such as rotational speed and pulsation frequency. A constant pulp density (25% solids) of the feed slurry was maintained in the study. The feed rate was also kept constant at 50 kg/hr dry solids. Silica sand of size -1.68+0.85 mm was used as ragging material to avoid the pegging of internal screen having an opening of 425 µm. The rotational speed was found to have significant effect on the depth of the ragging bed and its porosity, which influenced the separation performance considerably. Pulsation was identified as the key factor in stratifying the coal bed and defining the misplacement as well as ragging bed porosity, which influenced the mass yield and quality of the products. Beneficiation studies were carried out with rotational speed varying between 900-1000 rpm while pulsation frequency was kept within 850-925 rpm. In a single pass through the Kelsey Jig 7-8% (absolute) reduction in the ash content of the feed material was observed at more than 55% mass yield. High rotational speed, moderate pulsation, and low ragging bed depth favored good cleaning. A high bed depth was found to facilitate rejection of high ash materials. It was established that Kelsey Jig is effective in fine coal cleaning though a controlled operation is required in order to achieve superior performance. Keywords: enhanced gravity separator, g-force, separation performance, ragging material, coal beneficiation

Sep 1, 2012

By Yang Xiao, Zhang Yimin, Bao Shenxu, Liu Chun

Stone coal is a unique vanadium-bearing resource in China. Many techniques, such as salt roasting-water leaching, blank roasting-acid leaching, direct acid leaching etc. have been developed for vanadium extraction from stone coal. The vanadium leaching rate can reach 74.9% for stone coal from Jiangxi, but only about 27% of vanadium is leached for Hubei ore by applying salt roasting-water leaching technique. This paper investigats the vanadium occurrence in stone coal by microscope observation and electron probe, and compares the minerals components of stone coal from Jiangxi and Hubei. Although most vanadium exist as an isomorphism by replacing Al(III) from dioctahedral structure in mica group minerals in stone coal from two regions, the free vanadium is remarkably abundant in Jiangxi stone coal than in Hubei stone coal, which results the fact that vandium is relatively readily extracted from former. Moreover, the content of calcite in Hubei stone coal is much higher than that in Jiangxi stone coal. Calcium can react with V2O5 to form water insoluble calcium vanadates during roasting and this may be the reasone why the water leaching rate of vanadium is low for Hubei ore. Acid leaching is more beneficial to the vanadium leaching but other extra methods, such as adding aid-leaching agent and/or increasing acid concentration is need for the ore where vanadium is embeded firmly. This study can effectively guide the selection of vanadium extraction techniques for stone coal from different regions.

Jan 1, 2014

By Stefaan J. R. Simons, Michael T. Spyridopoulos

In this paper the effect of humic substances (natural surfactants), electrolytes and solid particles on bubble coalescence, and as a consequence on froth stability, has been investigated. We formed two bubbles of equal size and forced them to collide using a novel experimental apparatus. The interactions were recorded by a high-speed camera, the images of which helped to determine the coalescence frequency and the coalescence time, as well as the mechanisms of the interactions. Two types of humic substances were used, along with three different electrolytes. Humic substances appeared to have a considerable effect on bubble coalescence, while the effect of electrolytes was minimal. Moderate and high hydrophobic glass spheres were used between two bubbles. Very hydrophobic spheres promoted fast bubble coalescence, while moderate hydrophobic spheres had no effect. We present data of coalescence frequency and time, as well as images of the coalescence events.

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 S. Narra, M. Nelles, I. Eickhoff, S. Teitge

"The aim of the research is to develop a holistic process flow for the recycling of glass fibres from glass reinforced plastics (GRP) and carbon fibres from carbon fibre reinforced plastics (CFRP), wherein the dissolution of the fibre epoxy resin matrix, separation of fibre fractions and their renewed material use is intended. In clear distinction to the previous research and development projects, the aim here is to recycle complex composite structures such as dismantled/disused wind turbine rotor blades and end-of-life composite wastes. In the course of the study, mechanical, hydrothermal and thermal processes and their combined procedures will be developed. As the fibre length is a decisive quality criterion in the recycling of composite materials, the further focus of the study will be the development of upstream and downstream material processing, in which the fibres are retained in their original form. The evaluation of the recycled fibres obtained is based on the elemental composition, measurement and morphological evaluation of individual filaments by scanning electron microscope (SEM), micro tensile tests on single fibres and their comparison to virgin fibres. The resulting process water is analysed by gas chromatography and mass spectroscopy (GC-MS) and a potential recirculation is determined. In cooperation with companies from the composite processing industry as well as recycling companies, a return of the recycled fibres to the known manufacturing process will be examined and an energetic and economic evaluation of the overall process will be carried out. Ambitious aim of the study is to achieve an actual recycling instead of the present downcycling or the energetic utilization. INTRODUCTION As global warming increases, so does the awareness of consumption and production of energy. To counteract the effects of global warming, renewable energy has been increasingly used during the last two decades, not only in Germany, but worldwide. Both, hydropower and wind energy, hereby play a fundamental role. After the end of their useful life of 20 to 30 years, the wind turbines (WTs) are being dismantled. Due to their foundations and tower segments, their recycling rate hereby exceeds 90% by mass. So far, the resulting rotor blade waste played a minor role accounting for only 2 - 3 weight-% of the total plant. Rotor blades of modern wind turbines are made of glass and carbon fibers, which are embedded in an epoxy or polyester resin matrix, balsa wood, PU or PET foams as fillers as well as various paints and coatings. These wastes currently end up in waste incineration or are sold to non-European countries."

Jan 1, 2018

By Sergey S. Gudkov

In the current climate of changing the approach to mining and treatment of mineral resources, processing technologies are being developed that require little maintenance and are economically as well as ecologically sustainable. This may also involve the development of entirely new ways of ore processing. One promising approach is to use bioleaching for the pretreatment of gold refractory ores to cyanidation. Capital costs for vat bioleaching of concentrates and ores are very high and cannot be applied for small or medium-size deposits. IRGIREDMET JSC carried out bio heap leaching test work on refractory ore samples from three Russian deposits. Following this biological treatment a combination of flotation, vat bioleaching, and cyanidation are used to recover gold. After heap bioleaching, gold recovery was 75-80 per cent. It was found that efficiency of heap bioleaching process depends on ore feed size. High duration of this process is another feature and it lasts for about a year. This process can be also used for carbonates in the combination with other process during which acid generation occurs. The results of our studies have shown that this technology is amenable for refractory gold ores. Its introduction allows an increase gold recovery and to solve a number of environmental problems. Keywords: heap biooxidaton, the refractory of the ores, the degree of oxidation, arsenopyrite, pyrite, CIL

Sep 1, 2012

By Ernesto de la Torre, Karla Velín, Alicia Guevara

"The following study shows the improvement and simulation of a gold recovery plant of 24 t/day of capacity by gravity concentration, flotation and leaching. The ore processed had grades of 6 g/t Au, 15 g/t Ag, and 0.69 %Cu with the mineralogy consisting of 2 %chalcopyrite, 12 %pyrrhotite, 7 %plagioclase and 50 %quartz. The recovery process starts with crushing the ore followed by grinding it further in a ball mill. The ground ore is then concentrated in a Falcon centrifugal concentrator with concentrate being processed by amalgamation process. Gravity tails are sent to a flotation circuit where the copper minerals and some gold are concentrated. Lastly, the flotation tailings undergo cyanidation for gold recovery. Currently, the overall recoveries are 82.8 %Au, 49.6 %Ag and 99.1 % Cu. The optimization was developed in the laboratory using a Wilfley table by gravity concentration. Flotation tests in the laboratory were performed using potassium amyl xanthate and pine oil. Lastly, cyanidation was then performed on the flotation tailings. The results showed the optimum concentration of sodium cyanide in cyanidation is 2 g/L, which produced an increase in gold recovery from 30% to 44%. The reduction of diameter particle from 132 to 80 µm also produces an incremental recovery of gold and silver from 11% to 21% Au and 0.4 to 3% Ag in gravity concentration. Likewise in the cyanidation the recovery of gold and silver has shown a rise from 44 to 62% and 8 to 32% for Au and Ag respectively. However, the flotation method the gold recovery is reduced from 68 to 30% Au by reducing the particle size. Computer simulations using the programs, Moly-Cop and ModSim were performed to determine optimum parameters for the recovery of precious metals at the gold recovery plant."

Jan 1, 2014

By Nirmal S. Weerasekara, Malcolm S. Powell, Mohsen Yahyaei

"An understanding of the fundamentals of different breakage mechanisms is critical for successfully modelling comminution processes. Due to the high frequency of low energy collisions in the grinding process, superficial breakage has a significant role in size reduction in mills. To develop a scaling up methodology for characterising low energy surface damage behaviour of ores, a series of surface damage tests have been conducted using three grinding mill sizes with diameters of 1.8, 1.2, and 0.8 m. Two types of gold-copper ore with different hardness were used: C-ore and T-ore. All tests were conducted using wet mode to remove the products during grinding. To ensure low energy surface damage was the dominant mechanism, in all tests the mill speed was reduced to 40% of critical speed. A surface damage index normalised with product mass and surface based specific energy is determined from the results enabling a study of the grinding performance regardless of mill size, energy level or charge mass. Incremental breakage tests using the JKRBT indicate that the A×b values of the T-ore were 60% higher than C-ore, suggesting the T-ore is considerably softer. The fractional mass loss rate for the T-ore in the 0.8 m and 1.8 m mills started from 16 and 7 (1/kWh/m2) while for the C-ore it was 4 and 2 (1/kWh/m2). After 6 minutes the surface damage index in all tests tends towards steady state a constant value, an indication of steady state surface damage condition. It has been demonstrated that this methodology can be a useful basis for characterising superficial breakage behaviour of ores."

Jan 1, 2014

By M. Kosugi, M. Kawata, J. V. Satur, K. Mitsuhashi, R. Kawarabuki, W. Kracht, Y. Ebisu

Copper concentration is becoming more difficult because remaining copper ores are more complex and of finer copper mineral grain size, making copper minerals harder to float because of the fine particle size required to liberate the valuable species. The purpose of this work was to study the flotation behavior of fine copper sulfide ores at different conditions of agitation and aeration. The experimental campaign was carried out in a laboratory Denvertype flotation cell of 1 L volume modified to be operated with forced air that allows decoupling air flow rate and agitation speed. Four ore samples from Chile were used, all of them containing copper sulfides such as chalcopyrite, bornite, chalcocite, and tennantite, but with varying grain sizes and compositions. Preliminary flotation tests for establishing the flotation conditions of grinding size and collector dosage were conducted before the kinetic flotation tests that were carried out at different agitation speeds varying from 900 to 1300 rpm for gas flow rate ranging from 1.6 to 7.2 L/min. The flotation products were analyzed by ICP-MS and MLA (Mineral Liberation Analyzer). The results showed that high agitation speeds with corresponding air flow rates resulted in better recovery than moderate agitation speed and air flow rate, and an excess in gas flow rate resulted in bad performances. The flotation rates of the fine copper minerals were improved despite the different improvement rates among the fine size fractions. The impact of these operational variables, however, was different when comparing the results for the four ore samples. While it was found that the order of floatability in the four samples was the same, that is, chalcocite > tennantite > bornite > chalcopyrite, the kinetic constants of the copper minerals in the samples were different, indicating that mineral composition in the sample affects the flotation kinetics.

Jan 1, 2018

By S. Narra

Converting biomass into valuable fuel requires various preprocessing of the raw materials. Biomass densification is one of the conversion processes for its utilization. The aim of densification is to produce biomass pellets, which can withstand regular handling stresses and exhibit high densities with uniform size and shape. Physical properties, such as the particle size distribution after comminution is of highest importance for the binding mechanisms in the pelletisation process. Durability and strength of the pellets play an important role indicating the ability to withstand handling stresses. Particle size distributions of the cereal straws (Rye and Wheat) after specific comminution and liberation processes have been carried out with the help of three different image analysis (Microscope, Camsizer and Fibreshape). The durability of the pellets have been investigated as specified in the standards (ASAE standard S269.4) with a quadratic crate and the strength of the pellets with compression and tension testing machine (Zwick Roell type: ZMART.PRO). The particles size results showed differences in both length and width after different comminution processing. An exact comparison between the particle size analyses with the three different image analyses was not possible. The particle size distribution and the different comminution processes displayed influences on the durability and strength of the produced pellets. The particle size distribution displayed approximately 40 % of fines and 60 % of fibers. The particle size distribution displayed a direct relation to the durability of the pellets. Further durability and strength of the pellets displayed a good correlation.

Sep 1, 2012

By S. Banisi, E. Arghavani, Gh. Parsapour, S. Mousavi

Maximization of water recovery in thickeners is an essential step in the mineral processing industries. The Gol-E-Gohar iorn ore processing plant uses a center pier thickener with a diameter of 38 m and depth of 4 m. The feed rate is 50 t/h solids with a concentration of 5% (w/w), and it has been designed to provide an underflow containing 50% solids. The performance of the thickener was not as expected judged by the overflow stream containing 0.6% solids and water loss of 52 m3/h in the underflow. A criterion called the index of flocculation incorporating the perimeter-based fractal dimension of flocs, floc size, and settling velocities was proposed and used to determine the optimum flocculant dosage which was found to be 20 g/t. The fractal dimension of flocs in a pulp containing 5% solids was found to be between 1.16 (no flocculant) and 1.56 (40 g/t flocculant) which indicated highly branched and loosely bound structures for the flocs as flocculant dosage increased. At these conditions, the size of the flocs which was recorded by a digital microscope increased from 93 µm to 403 µm. A new feedwell with a special design with the aim of preventing flocs breakage and maximizing energy dissipation of pulp was constructed and installed. These modifications led to an increase in the thickener drivehead torque from 5% to 18% of the rated torque, indicating a higher bed depth. Finally, installation of a PID controller reduced the drivehead torque relative oscillation from 52.0% to 12.7%. These changes increased the solids concentration of the underflow from 49.0% to 56.9%, decreased the overflow solids concentration from 0.6 % to values smaller than 0.01% and resulted in a reduction of 27% in water loss in the thickener underflow.

Jan 1, 2014

By D. Bastin, J. Frenay, J. Dassas

"The Luiswishi deposit belongs to the Cu-Co deposits of the Southern Group of the Katangian Copper Belt and is operated by a joint venture between EGMF (Entreprises Générales Malta Forrest) and Gecamines (Générale des Carrières et des Mines). The Cu-Co ore is beneficiated by the sulphidization process at the NCK (New Concentrator of Kipushi) at Kipushi.Sulphidization followed by flotation with sulphydryl collectors is a common practice for the treatment of oxidized base metals ores. This process is complex and its application at the industrial scale is quite sensitive. In Central Africa it is also a cost intensive treatment as the sulphidizing agent has to be imported. In order to improve the metallurgical performances and to optimise the economics of the process, a laboratory research program was carried out by the Laboratory of Metallurgy and Mineral Processing (MTM) of the University of Liège in close collaboration with EGMF and Gecamines. This program included the study of various flotation reagents as dispersing, depressing and activating agents.This paper presents the results obtained with the use of ammonium sulphate as activator of the sulphidized xanthate flotation. Although ammonium sulphate has been mentioned in the literature as a promoting agent of the sulphidized xanthate flotation of malachite, its effects on the flotation of cobalt oxides was not known.The testworks were carried out on various oxidized siliceous ore types from the Luiswishi deposit. A 1.7 l Agitair laboratory flotation cell was used. NaHS and potassium amylxanthate were respectively choosen as sulphidizer and collector. A mixture of gasoil and tall oil (90/10) was used as secondary collector. A multistage sulphidization was realised. Values of pH were followed during the different tests and an ion selective electrode Ag/Ag2S was used to control the Es potentiel evolution during the stepwise addition of the sulphidizer."

Jan 1, 2003

By Polezhaev S. Yu, I. V. Ukraintsev, Boduen A. Ya, Saburbayeva L. Yu

"Comparison studies of different technologies are performed when selecting optimum option for gold ore and concentrate processing. Methods of ultrafine grinding, oxidizing roasting, bacterial leaching and pressure oxidation are used to extract gold from refractory ores and concentrates. Refractory gold flotation concentrate produced from pyrite-arsenopyrite ores of Bestobe deposit is a case study in this paper. The results of the experimental tests of the direct leaching of flotation concentrate and pre-oxidation products using different methods (oxidizing roasting cinder, pressure oxidation and bacterial leaching cakes) are the following: - cyanidation of original flotation concentrate provides recovery of Au at 46.6 %; - oxidizing roasting increases gold recovery from 46.6 % to 85 %; - BIOX increases gold recovery up to 86 %; - preliminary pressure oxidation of flotation concentrate ensures steadily high Au extraction in the follow-up cyanidation at 94.9-96.5 %. Pressure oxidation and bio-oxidation has changed dramatically the strategy of refractory gold ore processing. These solutions provided for development of ore deposits that considered earlier non-commercial. However, refractory ore processing has a complex character in terms of developing process flowsheet and requires large amount of studies to be performed for each new project. Gold extraction is the basic but not the only criteria to technology selection for gold ore and concentrate processing. Opex and capex, ore reserves, regional geography, developed infrastructure and skill personnel should be considered. Process studies and feasibility study of the developed technology shall be provided for each specific gold ore deposit. INTRODUCTION Due to changes in available feedstock and depletion of easy-to-process ores, refractory ores containing finely disseminated gold and silver in sulphides (primarily, in pyrites and arsenopyrites) are more and more involved into processing. Experts say that such ores amount above 40 % of the world’s gold reserves. Conventional technologies of gold extraction from refractory ores include flotation, roasting and cinder cyanidation (Fraser etal., 1991). However, today’s best available practice for refractory gold ore processing are bacterial (BIOX) and pressure (POX) oxidation."

Jan 1, 2018

By Andrei Yevdokimov, Ivan Sidorov, Olga Lanchakova, Olga Khmelnitskaya, Tatiana Chikina

"The paper focuses on the results of the research on development of hydrometallurgical process of gold recovery from refractory sulfide flotation concentrates based on fine and ultrafine grinding. Refractory concentrates (the degree of refractoriness is 16.9%-82.6%) were chosen for testing. The efficiency of the process based on fine and ultrafine grinding to treat flotation concentrates with gold intergrown with sulfides and rock-forming minerals was shown. Based on the test work conducted, the process option was chosen. In included grinding of flotation concentrate to the size of 98% minus 20µm in a bead mill, lime treatment with air blow, CIL, filtration and detoxification of liquid phase of the slurry. This process (compared to the basic option) provides the recovery of gold from 82.6%, up to 94.0% and decreases the residual grade in the tailings from 3.3g/t to 1.1g/t at the consumption of 12.6NaCNkg/t. Based on the results of the test work and pilot plant testing, project design criteria of flotation circuit at a Russian plant was developed."

Jan 1, 2014

By Valentin V. Shatalov, Irina V. Pastukhova, Alexander V. Kurkov

"We have developed a technology to improve the quality of low-grade concentrates containing minerals of tantalum, niobium and tin on the basis of given conception by the way of improving selectivity and using certain reagents composition. The basic collector presents a traditional or complex-forming collector used together with organic diphilic reagents – the secondary reagents regarding the basic flotation regiment, capable of forming associates with the main collector on the surface of the mineral, thus altering the interaction energy. In the given process the main collector is the fraction of hydroxamic acids C7-C9, the reagent of the secondary action – sulphosuccinamate, which added in moderate concentrations range provides for a synergistic effect.We have determined the parameters of the process stability and necessary modifying reagents for a selective recovery of tantalum, niobium and tin minerals from refractory products. Variants have been studied where the main collector and the secondary action reagent were substituted with some more efficient flotation reagents. A possibility of a more flexible reagent compounding for the process has been shown. The flotation process is highly stable regards the saline composition of the liquid phase in the pulp. It can operate under conditions of the complete water recycling with the total salt content up to 12 kg/m3, iron up to 1.2 kg/m3.The given results consider the efficiency testing of the suggested technology for the gravitation products, which were obtained from ores of various genesis and contain large quantity of the most refractory minerals, such as topaz (80%), gamet (55%), tourmaline (30%). High selectivity of the process has been registered with the metal recovery about 92-98%, which appears to be similar to hydrometallurgical operations under certain conditions."

Jan 1, 2003

By Isaak I. Maksimov, Tatyana E. Koltunova, Mikhail F. Yemelyanov, Liudmila A. Otrozhdyonnova

"INTRODUCTIONMetals losses amount up to 50% in coarse fractions in (>100 µm) and composite particles, and to 20- 25% in fine fractions (<10 µm) at non-ferrous floatation concentrating plants of the CIS. Therefore, reduction of metals losses in difficult fractions is of high significance.IMPROVEMENT OF FLOATABILITY OF COARSE AND COMPOSITE PARTICLESReagent regimes with application of strong collectors – xanthates ?5-?8, combination of butyl xanthates and aerofloats ?10-?12, butyl xanthates with hydrocarbons are proposed for this purpose. Application of such reagent regimes for copper and copper-molybdenum ores permitted to increase copper and molybdenum recovery by 0.5-3.9%.Studies, performed by means of specially designed non-frothing flotation machine with independently controlled agitation intensity and narrow size-ranges of air bubbles, established that the best results are achieved with employment of bubbles of 0.5-0.8 mm size regarding particles of any size, with small amounts of up to 2 mm size “transport” bubbles to be expediently used for floatation of coarse particles.Energy dissipation in the main volume of floatation cells must be lower than 0.2-0.25 m2/s3.Performed experiments permitted to formulate requirements to development of machine for floatation of coarse and composite particles. Such floatation machine with volume of 8.5 m3 provided for weak agitation in the main volume of floatation cell and uniform distribution of coarse particles throughout the depth owing to establishing of pulp circulation with upward flows. In addition, in the upper part of floatation cell where agitation is considerably weaker, favorable conditions are created for attachment of particles to bubbles. Testing of this floatation machine demonstrated a 7.5% increase in recovery of +0.2 mm particles in pyrite floatation and a 12-14% increase in recovery of +0.2 mm particles in apatite floatation as compared with a reference floatation machine."

Jan 1, 2003

By Yuemin Zhao

Pre-combustion cleaning of coal plays a key role in the process of efficient and clean utilization of coal resources. Recently, wet beneficiation of coal is predominant around the world. Nevertheless, wet beneficiation processes are limited by the increasingly serious problem of worldwide shortage of water, especially in China. Thus, it is imperative to develop efficient dry coal beneficiation techniques. Currently, several technologies such as air dense medium fluidized bed, compound dry cleaning and air jigging have successfully achieved high-efficiency separation of 50~6 mm coal. However, in recent years, a large amount of fine coal is generated as the mechanized mining technology has been progressively deployed in coal sector. Thus, it is necessary to develop efficient dry beneficiation techniques for fine coal. In recent years, many countries including China, India, Canada, Germen, and Australia have carried out many research works on fine coal dry beneficiation techniques. China University of Mining and Technology has carried out systematic researches on the introduction the vibrated energy to traditional air dense medium fluidized bed for fine coal beneficiation. This paper studied air dense medium vibrated fluidized beds (ADMVFB) for fine coal dry beneficiation. The experimental results show that the coal of <6 mm size can be beneficiated in an ADMVFB efficiently with the E value of 0.065~0.085, the separating density can be adjusted in the range of 1.45~2.2 g/cm3, and the lower limit of beneficiation can reach to 0.5 mm. Keywords: fine coal, air dense medium vibrated fluidized bed, coal separation, dry separation

Sep 1, 2012

By S. Banisi, A. Ghasemi, S. Zare, F. Ghorbani, E. Nematollahi

"Comminution is the most energy intensive operation which constitutes the major portion of operating and capital costs of the mineral processing plants. Working at the maximum operating capacity of comminution equipment plays a significant role in the efficiency of the circuit. Appropriate design of cone crusher feed box could result in the choked crushing which is known as a vital factor in achieving target performance. In this research, the non-uniform cone crusher feeding at the Sarcheshmeh copper complex was studied and appropriate measures were taken to solve the problem. The problem resulted in non-uniform and high wear rate of crusher liners and high fluctuations of power draw. In recent decades, the discrete element method (DEM) has been applied successfully to study the effect of different factors on the behavior of particles flow. In this work, various designs for feed box were tested using an in-house developed DEM software called KMPCDEM©. The best feed box design obtained from the simulations was selected, constructed and installed in of the cone crushers. The new feed box design resulted in more uniform feed distribution on the distributor plate of crusher indicated by a reduction of the standard deviation of power draw measurements from 13 to 3 kWh. The better control of the crusher, 49% increase in the crusher throughput and finer and narrower product size distribution were the main outcomes of the installation of the new feed box. Furthermore, the wear rate on mantle and liners of crusher not only decreased but it also became uniform.INTRODUCTION Comminution is the most energy intensive operation which constitutes the major portion of operating and capital costs of the mineral processing plants. Reaching the maximum operating capacity in comminution equipment is a key sign of approaching the nominal productivity of the process. Due to the effect of crusher efficiency on the downstream circuit performance, optimization of the crushing circuits has received considerable attention (Herbst, & Potapov, 2004; Quist, & Evertsson, 2010; Li, Huiqi, McDowell, Glenn R, Lowndes and Ian, 2014; Cleary, Sinnott, Morrison, Cummins, & Delaney, 2017). Improving the performance of crushing circuits not only decreases the capital and operating costs but also increases the efficiency of downstream grinding circuits (Jacobson, Janssen, & Urbinatti, 2010). In cone crushers particles can be subjected to two different modes of compressive breakage; single particle breakage (free feeding) and inter-particle breakage (choked feeding). The maximum efficiency of the cone crusher directly depends on the type of feeding arrangement (Operation Manual, 1977). An appropriate feeding must lead to choked feeding the cone crusher. If the rate and method of feeding the crushers are correctly be executed, the maximum efficiency of the crushers could be available (Jacobson et al., 2010)."

Jan 1, 2018