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By A. Javadi

"Our recent studies revealed that the sulfide minerals in contact with water during grinding produced hydrogen peroxide (H2O2) where the amount of H2O2 production by the minerals found to be in the order of pyrite > chalcopyrite > sphalerite > galena. The H2O2 effect on the oxidation of pulp components and its influence on the concentrate grade and recovery in flotation have been studied and the results have been presented and discussed in this paper. Studies have also been carried out to build correlation between percentage of pyrite in the concentrate, grinding conditions and concentration of OH•/H2O2 in the pulp and as well of controlling the formation of these species through known chemical means for depressing the generation of the oxidant. Flotation tests using a complex sulfide ore with the same reagent scheme that is being used at Bama concentrator in Iran but with the addition i) Na2S reductant and ii) inorganic (EDTA) and organic (TETA) surface modifiers, during grinding stage have been performed to judge the beneficial or detrimental role of H2O2 on the selective flotation of sulfides. The results demonstrate that the selectivity of metal sulfides against pyrite increases with increasing generation of H2O2 in the pulp liquid.INTRODUCTIONOur recent studies have illustrated the formation of hydrogen peroxide (H2O2) by metal-sulphides during grinding in the presence and absence of oxygen (Javadi Nooshabadi & Hanumantha Rao, 2013a; Javadi Nooshabadi & Hanumantha Rao, 2013b; Javadi Nooshabadi & Hanumantha Rao, 2013c; Javadi Nooshabadi & Hanumantha Rao, 2014). In the absence of oxygen, it was found that pyrite surface is catalytically active and able to breakdown water molecules to form OH• free radical and thereby deriving oxygen in the formation of H2O2 from water molecules. The in-situ formation of H2O2 and its influence on sulphide flotation has not been addressed yet. The presence of strong H2O2 oxidant in the pulp liquid and its selective oxidation of pyrite would be beneficial in depressing pyrite flotation. Therefore, it is important to build correlation between percentage of pyrite in the concentrate, grinding conditions and concentration of OH•/H2O2 in the pulp as well as to study possible ways of flexibly controlling the formation of these species through known chemical means for depressing the generation of the oxidant."

Jan 1, 2018

By I. Zimbovski, T. Ivanova, E. Chanturiya

"The mechanism of selective action of new reagent-collector AMD of phenylpyrazolone class with sulphide minerals of copper-zinc ores was theoretically and experimentally investigated. The validation was carried out using spectrophotometry, Fourier-transformed spectroscopy, laser scanning microscopy, analytical scanning electronic microscopy and flotation. The reagent AMD in alkaline medium on chalcopyrite and sphalerite surfaces is chemically sorbed, forming strong hydrophobic complexes with copper and zinc. On the pyrite surface, AMD acidifies ferric iron ions with formation of hydrophilic oxidates. The selectivity of collector AMD with separation of sphalerite and pyrite in alkaline condition (??=10) is confirmed by flotation experiments. With AMD, the obtained recovery of sphalerite was 34.4 % at extraction of pyrite of 3 and 6 %. The low recovery of sphalerite is caused by weak collective ability of the reagent. The use of copper sulfate increases the flotability of sphalerite up to 82.0 % at extraction of pyrite of 5 and 2 %. It has been experimentally determined that during the flotation of sphalerite and pyrite by AMD reagent with addition of butyl potassium xanthate, and in the presence of copper sulfate and regulator of formation of ammonium thiocyanate complexes, the recovery of sphalerite is increased to 91 %, while the recovery of pyrite is decreased to 3.8 %. The chalcopyrite is floated actively (90 % recovery). The results of all theoretical research and experiments were confirmed by flotation tests on ores and products of dressing in industrial conditions."

Jan 1, 2014

By A. V. Bogdanovich

Until recently, in consideration of fundamentals of gravity concentration theory, all computations have been based on determination of particles? fall velocity in an unrestricted medium (hydraulic size). Meanwhile, gravity separation processes are realized under conditions of particles? restricted fall, when important and sometimes decisive role is played by interacting forces of particles, dependent on their varying size, density and shape, i.e., segregation forces. We have developed devices and methods for measuring segregation velocities of fine particles of various size, density and shape during their loosening in air or aqueous medium. Besides, to exclude influence of medium upward flows, loosening was provided by superposition of vertical harmonic oscillations on measuring cell. It was established, that maximum segregation velocities are observed at certain optimal acceleration values and amplitudes of oscillations; excessive loosening leads to mixing and worsening of segregation. Velocity of some particles segregation through others depends on particles? size, density and shape, as well as nature of medium (air, water). Absolute segregation velocities of particles in air medium may reach 1~2 mm/s, in aqueous medium such velocities are by an order smaller. Analysis of rare-metal sands material gravity concentration results showed, that owing to segregation process during gravity separation, fine-size isometric particles of heavy minerals are recovered into gravity concentrates more actively, than larger ones, but more elongated in shape. It is convenient and simple to estimate mineral grains? shape by extent of their oblongness, described as ratio of particle minimal dimension to maximum. Besides, mineral mixtures gravity separation results are directly related to extent of oblongness of heavy particles, recovered in gravity separation process, and also to root-mean-square coefficient of their shape variation. The performed research showed that particles segregation in gravity concentration process plays not a lesser role, than hydrodynamics parameters, and demands further theoretical inquiry and experimental studies.

Jan 1, 2014

The relative abundance of coal in India compared to other fossil fuels makes it a natural choice as the primary source of fuel, be it for steel making, power generation or for other uses. The wide variations in nature and type of Indian coals formed during lower Gondawana period and categorized as difficult-to-wash due to its typical mineral matter association with the organic matrix call for suitable beneficiation techniques as the preferred option for quality upgradation. The good quality coking coals of the upper seams are fast depleting leaving behind the inferior quality lower seam coal. The lower seam coals presently being mined are mostly low volatile coking coal (LVC). They constitute about 50% of the total coking coal reserves in India. The beneficiation of Low Volatile Coking coals pose a major challenge and detailed R & D studies was taken up to study the beneficiation characteristics of these coals. The studies revealed that the liberation characteristics at coarser sizes are very poor and the coal is to be ground to finer sizes for liberation. The most important factor that determines coal cleaning efficiency is liberation of organic matter from mineral matter. To achieve liberation grinding is necessary as a result range amount of ultra fines (-0.063 mm) coal is generated. Presence of these large amount of ultrafine in the coal fines, often impose severe technical constraints affecting not only its floatability but also in the downstream treatment of the products like dewatering and cake formation particularly when it is beneficiating through froth flotation. In the present paper optimization of ultra fines (-0.063 mm) has been tried for a LVC coal of Jharia coal field for the better liberation and beneficiation of the above coal fines. It is observed that by optimized, combination of size and number of balls generation of fines can be controlled with liberation. Keywords: coking coal, liberation, floatability, dewatering

Sep 1, 2012

"The research aimed at solving the problem of measuring instantaneous local physical quantities for multiphase flows in mineral processing, which are common in minerals industry and with significant challenges. Due to the lack of proper measurement tools currently in minerals industry, multiphase flows (such as in flotation cell) are treated as in a “black-box”. It is crucial to develop measurement technique by which the acquired processing data can be used for process optimization and control. By measuring the conductivity distribution across a measurement area, Electrical Resistance Tomography (ERT) has been adopted by many researchers to monitor and investigate many processes involving multiphase flows in other industry sectors. A compact ERT probe was built and then used to measure the conductivity distribution within a few flotation machines. In a flowing foam flotation column, the results showed that ERT can accurately measure the change of liquid content (high conductivity fluid distribution). In another part of work, based on the Green-Kubo relations, ERT can measure turbulence via the fluctuation of conductivity caused by bubbles moving through the measurement area, changing the density of the fluid. The tests with the Metso 3 m3 RCS flotation cell were also carried out for turbulence measurement under different air rates and impeller speeds. The results of flotation cell from ERT measurement showed that varying impeller speed had more pronounced influence than changing air rate. When impeller speed is increased, the size of the high turbulent zone increases. ERT is a powerful technique that has the potential to be used for a wider range of applications. The future work will be carried out with more case studies and expanded to more processes such as leaching process, high temperature flows in further downstream production chain (steel making process and alloy manufacturing process).INTRODUCTIONMultiphase flows constitute a majority of the naturally-occurring and industrially-relevant flows, especially in mineral processing. Some of the measurement techniques have been used for the study of fluid characteristics. Optical techniques such as Laser Doppler Anemometry (Kyselaa et al., 2013) and Particle Image Velocimetry (Nobach and Bodenschatz, 2009) can produce accurate measurement results with high spatial and temporal resolution, but their applications are limited to transparent flows. Hot wire probes (Amini et al., 2013) have high spatial and temporal resolution in turbulence quantification, but they are susceptible to environmental factors."

Jan 1, 2018

By Barun Gorain, Aparup Chattopadhyay

"Many double refractory gold deposits are characterized by the dominance of ""invisible gold"" (sub-microscopic gold) as solid solution or as colloidal-sized particles in different sulfides and other phases. These deposits are mainly composed of silicates and carbonates with moderate clay and mica content and with minor amount of sulfides and organic carbonaceous matters. The presence of highly preg-robbing and finely disseminated carbonaceous matter adversely affects gold recovery in leach circuits. Characterization of carbonaceous matters, commonly known as TCM and quantification of gold associated within these carbonaceous matters along with different sulfide and oxide phases is highly complex and challenging. Studies were initiated on various complex ore deposits and also on samples representing various process streams. This paper presents the development of a systematic approach to gold deportment studies using state-of-the-art mineralogy characterization techniques for quantification of invisible and visible metal contents in various species. The relevance of this mineralogy characterization to metallurgy will also be discussed in this paper."

Jan 1, 2014

By Montaser S. EL Salmawy, Takahide Wakamatsu, Eishi Kusaka

"In conventional flotation, fluoride ions selectively would react with the aluminum site on the microcline surface and produce negative charged sites for amine to be adsorbed (Smith, 1976). According to this view, aluminum site is considered as a key feature in feldspar flotation. Generally, fluoride ion has been widely used as a modifying agent in silicate flotation. Since O'Meara's patent appeared on HF -amine reagent system to selectively float feldspar from quartz in 1942, relatively few contributions have been devoted in this issue. The reason might be that the process works very well, and accordingly there is no initiative to investigate in this area. However, due to the awareness of international community to restrict using of hazardous reagents like HF, sound engineering practice to search for alternative methods, not utilizing HF, has been launched. Inspection of literature, one can find several works dealing with this issue.In this contribution, the effect of ethoxylation of long chain alcohols on the quartz and feldspar flotation behaviors was investigated for surfactants of the octylphenol polyoxyethylene family. The tests were carried out with an average of 7.5 (Triton X 114), 9.5 (Triton X 100), 30 (Triton X305), 40 (Triton X 405) and 70 (TritonX 705) oxyethylene units. Electrokinetic and flotation studies on quartz have shown that at low pH values, quartz could be floated with polyoxyethylene octytlphenols. The possible mode of adsorption of these nonionic surfactants may be suggested to be due to hydrogen bonding between the oxygen of ether and hydrogen in the free hydroxyl groups on quartz surface. It was anticipated that the selectivity between quartz and microcline would decrease as oxyethylenic chain length increases."

Jan 1, 2003

By G. Kumar

Water for domestic consumption is an essential right of society, which must be over secured. Water reclamation and reuse provides a unique and viable opportunity to augment traditional water supplies. As a multi-discipline and important element of water resource development and management, water reuse can help to close the loop between water supply and wastewater disposal. Effective water reuse requires integration of water and reclaimed water supply functions. During the coal mining activities, large quantities of water get contaminated and loses its potability characteristics. On an average, in coal mine operation, each coal mine discharges effluents at a rate of nearly 0.5 MGD and thereby wastage of nearly 50 MGD of water takes place per day from the famous Jharia Coal Field of the Dhanbad District. In this paper, attempt has been made to control the extremely high turbidity of mine waste water by using different coagulants and it is observed that ferrous sulphate is the most effective coagulants followed by alum, ferric sulphate and lime. Also combinations of coagulants are used for getting the optimal results. Further steps were also discussed to make this water potable and a scheme of low cost water supply system of mine waste water has been suggested under the Water Management Strategies. Keywords: potability, turbidity, coagulants, water management strategies

Sep 1, 2012

By Xu Wang, Bang Chen, Xiujian Luo, Wei Tang, Xiao’ou Xia, Fangming Liu

"The inertia cone crusher has lots of advantages, such as big crushing ratio, fine particle size, material layer crushing, good passing tramp iron performance and stable technical index, realized open crushing circuit and simplified crushing flowsheet. The crusher was input to China’s Beijing General Research Institute of Mining and Metallurgy (BGRIMM) from Russia’s Mekhanobr-Tekhnika Research & Engineering Corporation at the beginning of the 1990s. This paper introduces that after years of absorption and innovation how Chinese researchers optimized and creatively designed about transmission mechanism, bracing structure, kinetic parameters, lubrication system, dust sealing system, damping system and hydraulic control system etc on the basis of keeping its advanced theory and unique structure, therefore the crusher’s stability was raised and the usage cost was reduced greatly. Accordingly the inertia cone crusher in China has been widely used in many fields, such as mineral resources and the recycling of metallurgical slag. The achievement in cooperation was fully affirmed by governments of Russia and China, and cooperation of science and technology in the mining and metallurgy industry between Russia and China is promoted greatly. INTRODUCTION From the early 1950s, the former Mekhanobr Institite(now Mechanobr-Tekhnika Research & Engineering Corporation) devoted itself to the research of inertial cone crusher and put it into industrial application in the late 1980s. Inertial cone crusher is like a maverick flower in the field of crusher. With its excellent performance and excellent application effect, it shocks the world and is destined to shine with a bright future. In the early 1990s, the chief leaders of the Beijing General Research Institute of Mining and Metallurgy (BGRIMM), Academician Sun Chuan-yao and Professor Zheng Baochen, captured the extraordinary performance and strong vitality of inertial cone crusher with keen eyes. So the two big institutes started the cooperation to introduce inertial cone crusher to China. Since then, Inertia cone crusher has been able to flourish in China and have achieved impressive results with two institutes’ continuous effort."

Jan 1, 2018

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

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

Jan 1, 2018

By Y. Foucaud, I. Filippova, L. Filippov

Flotation is the most common beneficiation route for tungsten ores, but the predominance of minerals with similar surface properties poses a real challenge. This study investigates the use of Falcon centrifugal separators for gangue minerals removal and desliming prior to flotation. A typical tungsten-bearing skarn ore (Tabuaço, Portugal) is used, containing scheelite (CaWO4) associated with dense calcium-bearing silicates (vesuvianite), fluorite, apatite and light silicates (feldspars) as gangue minerals. Two types of Falcon bowls (Falcon UF and Falcon SB) were used, prior to flotation tests with fatty acids as collectors and a combination of sodium carbonate and sodium silicate as gangue minerals depressants. This flowsheet was compared with a reverse configuration, using flotation prior to Falcon concentrator, and with a classical flowsheet, using hydrocyclone and flotation. Gravity pre-concentration and desliming with the Falcon concentrator were optimized through the design of experiments (DoE) methodology. The influences of pulp density, rotational speed, feed flowrate and fluidisation pressure (for the Falcon SB) were studied for both bowls. Results showed that the Falcon can be used as a desliming and pre-concentrating apparatus. Separation performances depend mainly on rotary speed and pulp density for the Falcon UF, whereas rotary speed and fluidisation pressure are the main parameters for the Falcon SB. With only one stage of Falcon SB, an enrichment ratio of 7.9 is obtained with a 65% WO3 recovery while 89% of apatite and fluorite are rejected, which constitutes a very good selectivity. In comparison, Falcon UF shows lower enrichment ratios, around 2.7. In terms of desliming, Falcon UF is as efficient as the hydrocyclone, while the Falcon SB is significantly more efficient. Hence, the use of Falcon SB prior to flotation improves the overall performance of the tungsten flotation route by desliming the flotation feed while pre-concentrating the scheelite. It impacts very advantageously the flotation, as most of the calcium-bearing minerals are eliminated. A Falcon SB stage prior to flotation yields a final concentrate grade of 29.7% WO3 with a recovery of only 36.8 % that should be optimized as the reagents dosages were not adapted to the pre-concentrated feed.

Jan 1, 2018

By Peter J. Scales

The recovery of water for re-use in minerals processing is an important issue in the reduction of water use in mining, as is the dewatering of tailings to reduce the propensity of ?wet? tailings dams. It is common in these dewatering operations to use thickeners whereby polymeric flocculants are combined with the dilute feed to the thickener to aid sedimentation and the subsequent consolidation of particulate materials. Thickeners are the workhorses of water recovery and tailings dewatering and although the basics are well understood, there is still no ability to reliably predict the throughput and underflow density from a thickener based on traditional sedimentation tests and flux analysis. The reasons for the discrepancy between full-scale operations and predictions based on laboratory tests are numerous, including difficulties in mimicking the flocculation conditions experienced in the field and the shear conditions in the thickener. The latter effects are little understood and hard to quantify and include effects due to flocculated aggregate densification, complimentary shear and compressional effects and aggregate break-up. Developing a set of test protocols to quantify the effects of densification, shear in compression effects and aggregate breakup and the subsequent contributions of each to compressional dewatering in a thickening environment has been completed for a simple model polymer flocculated particulate suspension. The data and analysis shows that aggregate densification is a dominant contributor to the difference between observed and predicted behavior based on laboratory tests. A major consideration in the analysis is the fact that common thickener operations are permeability limited and although the various effects are all important, the one that results in the fastest water release is dominant. Of interest also are the shear rate, concentration, and time dependence of the aggregate densification process. A basic model of the process has been developed along with network yielding tests conducted using rheometry. Keywords: compressional dewatering, gravity thickening, rheometry, aggregate densification, raked batch settling

Sep 1, 2012

By T. C. Sun

Two wasted activated sludges (WAS), from an industrial wastewater treatment and a sewage treatment plant respectively, and 7 collectors are used to investigate the feasibility of air flotation thickening of WAS by adding the collectors used in mineral processing. The collectors experimented include straight chain fat acids with different chain length, sodium oleate, alkyl sodium sulphonate, sodium dedecylsulfonate, and dodecylamine. The results show that the thickening efficiency varied depending on different collectors. Of the collectors experimented, dodecanoic acid and dodecylamine are best collector for thickening both sludges.

Jan 1, 2014

By I. Nishkov, I. Grigorova, M. Ranchev, S. Dzhamyarov

"Chelopech concentrator (part of Dundee Precious Metals) is located in central-western Bulgaria. The current process plant utilizes conventional primary crushing and SAG mill grinding, copper and pyrite rougher and cleaner flotation stages to produce a marketable gold-rich copper and pyrite concentrates. As in the most processing plants, the pyrite depression is carried out alkaline media using lime. The subsequent activation of pyrite mineral is achieved by adding sulfuric acid, which has an adverse effect on the flotation equipment. Therefore, a series of laboratory flotation experiment for activation of lime depressed pyrite by ammonium salts, such as ammonium chloride (NH4Cl), ammonium sulfate (NH4)2SO4 and ammonium bicarbonate (NH4HCO3), have been conducted. The obtained results showed that ammonium bicarbonate proved to be the most appropriate reagent choice for pyrite mineral activation. These results are confirmed by X-ray photoelectron spectroscopy (XPS), performed to determine the surface chemistry of pyrite in its natural state, after lime treatment and subsequent treatment by NH4HCO3. The registered XPS spectra indicate that the hydrophilic phases on the pyrite surface could be efficiently removed by using the ammonium salt NH4HCO3. The industrial use of NH4HCO3 as an activator of lime-depressed pyrite is a possible alternative for sulfuric acid replacement as a most widely used pyrite activator. Flotation experiments with addition of 200, 400, 600 and 800 g/t from each of the studied ammonium salts have been conducted. Furthermore, the impact of the flotation pulp pH within the scope of 9.00 – 10.50 was also investigated. The obtained results from the laboratory flotation experiments, showed that the pyrite activation with ammonium bicarbonate is an excellent possibility for replacing the sulfuric acid as main pyrite activator reagent, in order to eliminate the gypsum accumulation during the flotation of pyrite in Chelopech concentrator.INTRODUCTION The Chelopech deposit, located about 60 km east of Sofia is one of the largest Cu-Au deposits in Europe. The ore have complicated mineralogical and chemical composition. The main ore minerals are represented by pyrite, enargite (luzonite), tennantite, chalcopyrite and bornite. The average copper content of the mined ore is about 1.1 % and the gold content is about 4.0 g/t."

Jan 1, 2018

By V. M. Mankov, O. V. Zamyatin

"Fine free gold at a size of minus 250-100 µm can be effectively recovered from mineral materials (buried clay placers, saprolites, gold-bearing aggregates, technogenic sands etc.), or MM, using some developed and implemented in practice cost-effective basic technological schemes of MM processing at every stage: exploration, main concentration processes, upgrading of gravity concentrates etc. Such technologies are based on mineral materials composition, different content of fine gold mass fractions, and include improved two-stage sluicing technology, jigging technology, advanced technology and integrated technology. The main operation principle of the given technologies is gravity concentration. They provide recovery of fine gold of any size from MM, including gold finer than 100 µm, using concentration systems and plants with a capacity of 1-2 and up to 100-200 m3 per hour. Selection of a cost-effective technology depends on its technical and economic viability regarding to mineral material composition, optimum performance and concentration rate. The developed technologies of mineral materials concentration establish a balance between technological, technical and economic factors, and ensure profitable development of deposits containing free gold and characterized by a complex composition of concentrating material. Free gold recovery with these systems increases by 2.0-2.5 times for gold particles at a size of minus 250+100 µm and 10-30 times for gold particles of minus 100 µm, compared to conventional sluicing systems. The Irgiredmet Institute has developed and supplies primary concentrate washing machines for upgrading gravity concentrates of up to 100 mm in size, with a capacity of 1.0-5.0 m3/h, fitted with various production equipment including pyro- and hydrometallurgical systems. Additionally, the Irgiredmet Institute develops and manufactures systems of mechanized processing of geological and technological samples (UOMP; registered design certificate No.27505, Russia) designed for complete recovery of free gold in the process of geological samples handling and decreasing of a human factor influence. A system includes a package of technologically associated disintegration, classification and concentration equipment with some “know-how” elements that provide effective recovery of fine gold at the exploration stage. A number of Irgiredmet’s patented technologies and systems (patents of the Russian Federation) have no equivalents in the field of mineral processing and provide designing of technologically practical and cost-effective flowsheets that offer higher recovery of gold of different sizes (fine gold), at every stage of processing of mineral materials including basic concentration processes, upgrading and exploration etc."

Jan 1, 2018

By Tohru Kamo, Shigeyuki Katano, Hideki Nakagome, Maiko Adachi, Shingo Nakamura, Kaneshi Taniguchi, Zar Zar Hlaing, Takaaki Wajima

Tantalum capacitor is a small-sized and has large capacity, and is indispensable for electric equipment. The demand increases year by year, and a quite large number of used tantalum capacitors is generated. Recovery of tantalum from tantalum condenser is recently important since production of tantalum have not been stable for the price and the quality. However, recovery of tantalum from tantalum-condenser is difficult since tantalum parts strongly cover with the flame retardant resin made of halogenated compound (mold resin). This research investigated recovery of tantalum parts from tantalum condenser using steam gasification with mixed molten carbonate. Mixed molten carbonate (Na2CO3:K2CO3:Li2CO3 = 1:1:1) (3 g) put into the reactor, and heated with electric furnace while flowing nitrogen (160 mL/min) and steam (1 mL/min) warmed by heater. After heating to setting temperature (450 - 650 oC), tantalum condenser (3 g) was put into the reactor, heated for 5-10 min, and then cooled to room temperature to recover the reacted capacitor by filtration after treating with distilled water. At relatively low temperature (550 oC) heating for 10 min, mold resin can be decomposed by using steam gasification with mixed molten carbonate, in comparison with using pyrolysis and steam gasification without carbonate, and decomposition reaction occurred over 500 oC by using steam gasification with mixed carbonate. Recovery of tantalum parts from capacitor is successful using steam gasification with mixed molten carbonate at 530 oC for 5 min, due to the effective decomposition and removal of mold resin from capacitor. Furthermore, most halogen gas generated from decomposition of mold resin can be trapped in molten carbonate not to exhaust halogen gas. These results suggested that recovery process of tantalum parts from used condenser using steam gasification with mixed molten carbonate is expected as a feasible way to recycle the rare metal in electric equipment.

Jan 1, 2014

By Wayne van Drunnick, Mervyn Ruthnasamy, Olvier Guyot, Christophe Bouché

"Anglogold’s Mponeng Mine is situated in South Africa’s North West Province approximately 80km from Johannesburg. The reefs being mined in this area are among the deepest deep level mining operations in the world. These shafts often exceed several thousand meters making these operations complex and expensive.The gold plant is fed with run-of-mine ore which is stored in mill silos. Feedrate to the mills is controlled by a variable speed belt. Three parallel SAG mills (4.85 x 9m) treat 80-100tph, operating in closed circuit. Hydrocyclones classify the mill discharge, returning the oversize to the mill feed. Cyclone feed density and pressure are measured and are used with typical control loops to determine water addition rates to the mill. Control loops at PLC/SCADA level were historically used with limited success in the control of the milling circuits. Mill control for an installation of this type used mill mass (measured by load cells) and feedrate to control throughput. An online particle size analyser (PSI) was installed to assist grind control in tandem with pressure/density control on the cyclones. Although the accuracy of the measured grind was reliable, long term consistency of the PSI could not be guaranteed. Economic pressure from the business sector requires consistent mill throughput at optimum grind conditions. Fluctuations in production targets can manifest due to inconsistent control and the lack of real-time information from the process.This sensitivity to process movements may vary between shifts and also with changes in ore competency.Whilst tools are available to improve control, few have the sensitivity to process movements to provide real-time information for optimal grind control. For this reason an Advanced Control solution was sought. Advanced Control is often described as the supervision of basic PLC/SCADA control. Advanced control systems have to seamlessly compliment the existing control strategy and bridge the gap that exists between basic control and optimised control. A solution was found in the Metso Minerals CISA’s OCS (Optimising Control System). This French designed system makes changes to process setpoints to achieve peak performance and is distinguished from others by its soft sensor capabilities. The soft sensor is an embedded module in the OCS package that can be configured to estimate values normally obtained from field instruments. Advanced control using a Fuzzy Expert System assisted by Statistical tools (such as moving averages and a Soft Sensor using Phenomenological Models) would serve to bridge that gap. Metso Minerals CISA’s OCS is a modular system with various capabilities.It was successfully used to provide on-time process information via Soft Sensors. Circuit stability was achieved using Rule Based Expert Control in complete synergy with Fuzzy Logic. Two rule-based strategies were developed for this circuit. The first uses the online product size analyser as a primary control variable. The second uses a calculated kWh/t value and a modelled mill discharge density as primary control variables. The latter had more availability than the particle analyser and is currently in use."

Jan 1, 2003

By Peter Scales, Ricardo Jeldres, Fernando Concha, Pedro Toledo, Shane Usher, Anthony Stickland

The impact of several electrolytes present in seawater on the rheological properties of flocculated mineral suspensions was assessed using the creep test. Flocculated suspensions were obtained by adding polymer flocculant to a cylinder of mineral suspension and aggregating the suspension using the plunger method. The suspension was allowed to sediment and the supernatant liquid decanted prior to tests for the viscoelastic properties of the resulting sediment. The solid used was alumina AKP-30 both, below and above the isoelectric point. The polymer used was AN934SH, an anionic flocculant with high molecular weight. Salts analyzed were MgCl2, CaCl2 and NaCl, known as water structure makers, and KI and KCl, known as water structure breakers. A high salt concentration of 0.5 M was used to approach the ionic strength of seawater. For both pH’s studied, the sediments demonstrated a viscoelastic non-linear behavior observed as a non-linear relationship between yield strain and applied stress. In the absence of flocculant, it was observed that the viscosity and yield stress of a suspension increase in the presence of structure maker salts for the case of both silica suspensions and alumina suspensions. These results were explained using hypernetted chain statistical mechanics models describing the interaction of ions with solvated surfaces. In contrast, with the presence of flocculant, the shear yield strain of alumina suspensions increases with the breaker character of the salts, however, this result has been explained by an extension of the results from the models. The work has significant implications for the flocculation of mineral suspensions in the presence of seawater.

Jan 1, 2014

By Nicholas Enraght – Moony, Alvin Johns, Zhonghan Zhang, Zhang Xianhua, T. Choo

"The tungsten (WO3)-rich ores from King Island Scheelite (KIS) Mine, Australia, containing scheelite(CaWO4) were previously recovered by gravity separation and flotation of fine scheelite (1978-92) with an overall recovery of 76% when both circuits were operating. Recently extensive test work has been conducted both in China and in Australia on KIS ores, assaying from 0.50%-1.34%WO3, and tailings assaying 0.2%WO3(GZRINM 2009; 2011a; 2011b). A new approach, which aimed at improving both recovery and grade of concentrate by means of an innovative all flotation route WOF (Whole Ore Flotation), achieved excellent results: 90%-92% recovery to concentrate grade of 66%-70%WO3for the ores. The process is characterized by the use of selective reagents in flotation, including a newly developed collector for scheelite, GYWA. The WOF process also embraces the "Improved Petrov Method" in the cleaning of scheelite rougher concentrate. Earlier investigations found that the removal of sulfides by flotation prior to scheelite flotation was not necessary. It was also found that recycling of process water did not influenceresults. Two main ore types were tested as well as tailings from 2009to 2001(0.20%WO3). In addition a flow sheet using wet high gradient magnetic separation (WHGMS) in tandem with flotation was also investigated for the tailings."

Jan 1, 2014

By D. Jamróz, A. Surowiak, T. Niedoba, P. Pieta

"The separation of coal material of three types of coals originating from three various Polish hard coal mines (types 31, 34.2 and 35, according to Polish nomenclature, which were steam coal, semi-coking coal and coking coal) into particle size fractions and then into particle density fractions was done and then the following parameters were measured for each particle size-density fraction: combustion heat, ash contents, sulfur contents, volatile parts contents, analytic moisture. In this way a 7-dimensional vector of data was created. Using methods of factor analysis the important features of coal were selected, which decide about their membership to individual types. To evaluate the appropriateness of the applied method the Bartlett’s sphericity test as well coefficient of Kaiser-Mayer-Olkin (KMO) were used. To select important factors the Kaiser criterion and Cattell’s scree test were used. The obtained results were compared with the results obtained in previous works by means of observation tunnels method. The results showed which particular features are crucial to define the type of coal what is also important to select appropriate method of its enrichment.INTRODUCTION Coal extracted from the mine is often a mixture of coals of various quality originating, for example, from various coal layers. One of the most important issues is to determine its quality, what means to verify if it fulfills certain requirements. Usually, such parameters as combustion heat, ash contents, sulfur contents, volatile parts contents and analytic moisture decide what the coal quality is (Drzymala, 2009). Such investigations are expensive and time consuming. That is why it seems to be important to determine the mutual connections and interactions between them what would make possible to reduce the amount of the necessary parameters. This issue was already investigated with successes in several works [Jamróz and Niedoba, 2013; 2014; Niedoba, 2015]. This work is another approach to this problem. Here, the investigation of possible reduction of researched parameters was done on the basis of the factor analysis. The obtained results confirm the earlier observations."

Jan 1, 2018