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By Bhargav Dhavala, Sristy Raj, Ashok Kumar, Suman Krishna Sit, Adity Ganguly, D. P. Chakraborty

"Tatasteel’s West Bokaro washery#3 is designed to deslime raw coal at 0.5mm; the oversize (+0.5mm) is beneficiated in dense media cyclones (DMC) while the undersize (-0.5mm) is beneficiated in froth flotation (FF) cells. Nearly, 80% of the raw coal feed reports to the DMC circuit consisting of four parallel streams. Presently, the performance of DMCs at washery#3 is interpreted by: (a) comparing the actual plant yield w.r.t the lab predicted yield and (b) misplacement of clean coal to middllings.However, the comparison between actual & lab predicted yield is fallacious given the fact that the lab predicts yield of the borehole sample while the feed received at the plant has different characteristics altogether due to the dilution during mining. To mitigate the said limitations, a quick diagnosis tool using the past data has been developed that will give a prediction of performance of different coal seams in the DMCs, inputs being feed ash to DMCs and stream wise feed specific gravity (coal & magnetite combined).The tool also will help in identifying the root cause on real time basis thereby helping the operator to take necessary corrective actions. The operator can intimate the mining personnel in cases of shale reporting to the feed as a result of dilution during mining. In events of higher standard deviations between the parallel streams w.r.t feed specific gravity, the operator can adjust the parameters accordingly to minimize the yield loss. INTRODUCTION West Bokaro came into existence in 1948, as an independent coal company, managed by M/S Anderson Wright. Tata Steel acquired the Company in 1956 to meet its requirement of metallurgical grade coal for Iron making. Subsequently, in 1976, it was made a division of Tata Steel. In 1974, when coal mines were nationalized, West Bokaro was exempted as it produced coal only for captive consumption of the Steel Works. The first washery of India was set up in West Bokaro. The business objective of the West Bokaro division is to produce clean coal at optimum cost for captive use in the steel plant of Tata Steel at Jamshedpur. The strategy is to reduce ash with minimum loss of yield so that quality of coal improves and yet the cost is beneficial vis-a vis imported coal. The primary product is the metallurgical grade coal for coke ovens, which converts coal into coke for use in the Blast Furnaces."

Jan 1, 2018

By U. A. Peuker

"Steam Pressure Filtration (SPF) is a modified cake filtration process and is characterized by both washing and excellent de-watering of the filter cake. Compared to conventional gas differential pressure filtration, the filter cake is treated with saturated or superheated steam replacing pressurized air. Invented in the early last century, Steam Pressure Filtration has reached technical maturity in the 1990ies for inorganic particle systems, fine chemicals and coal. Especially the de-watering performance for fine particles systems below 50 µm make Steam Pressure Filtration an excellent option for the processing of fine tailings streams, to produce a stable material, which can be described by the methods of solids mechanics instead of paste rheology. The washing, which is due to the condensing steam, is able to reduce the ion load of the solid. This additional effect is able to generate a dry tailings material, which shows a reduced leaching potential of mobile ions, which originally derive from the process water. INTRODUCTION Steam Pressure Filtration is a process concept especially of hyperbaric filtration, which started its market entry in the 1990ies (Bott 1996, Bott 2002). Even though there have been many attempts to apply steam on filters before, the success story began with the combination of hyperbaric filtration and steam application and the technical solution to limit the steam treatment to a defined zone on the filter. This resulted from the scientific findings that steam mainly enhances the de-watering during the mechanical filtration (Gerl 1999). There are no or minor positive effects of steam application to a filtration process during cake filtration and after the steam breakthrough has occurred. Furthermore that time a sufficient control technology to regulate the steam consumption as well as suitable filter cloths became available. There is a growing need for de-watering technology in the mining industry, not only for the concentrate but also for the tailings streams. Several reasons argue against the established solution of damping the tails as suspension or paste into tailings ponds. There are ecological, political, societal and economic reasons, which question the tailings ponds more and more. Due to the increasing costs in the building and monitoring of tailings dams, which contain the tailing ponds, the concept of dry stocking using filtration technology comes into the game (Jansson 2016). Dry stocking converts the tailings stream form the suspension or paste state, into a material, which can be stockpiled. The latter typically is a moist flowable disperse particle system. The conversion involves a de-watering step, in which different types of filter equipment can be used, e.g. filter presses, membrane filter presses, automatic press filters or hyperbaric filters. For coarse products also vacuum filter can be applied. Due to its excellent de-watering performance and the easy scale-up properties Steam Pressure Filtration is further option for dry tailings stacking."

Jan 1, 2018

By M. R. Tavakoli Mohammadi

Novel solvent extraction technologies in recent decades have made attempts to show the problems in applying this method for dilute solutions and find appropriate solutions to overcome them. Improving the equipments performance used in this method for dilute solutions, cause development of usable resources and reduction of operational costs. Furthermore, appropriate conditions provide for using dilute solutions produced in various industries as a new source of valuable elements. Thus, this proposal can be a very good solution for treatment of these solutions and reduce the environmental impacts associated with them. The purpose of this study is to introduce a new method of Column Floto Extraction (CFE), which has been invented in this regard. In this method, using spargers similar to Jameson cell downcomer in floatation process, the organic phase bubble dispersion has been used instead of its drop dispersion in aqueous phase for the two-phase mixture operation. This operation mode has caused a higher extraction percentage of solute in high aqueous to organic ratios due to enhancement of contact area. In this study, in addition to explaining the advantages and features of this method, we have dealt with its design and performance mode.

Sep 1, 2012

By Y. B. Zhang

China is rich in iron ore resources, but most of these ores are low-grade, polymetallic and refrac-tory ones. Furthermore, with the rapid development of chinese iron & steel industry, the comprehen-sive recovery of these ores is becoming more and more important. The tin, zinc-containing complex iron ores are typical polymetallic and intractable ones, and great reserves of them are found in China. At present, they have not been efficiently utilized. In this paper, based on the investigation of basic physicochemical properties of the tin, zinc-bearing iron concentrates, taken from a mineral processing plant, the mineralogy reason that these concentrates are so intractable and refractory is found out, using advanced microscopic testing methods, such as optical microscope (OM), Scanning Electronic Microscope (SEM), X-ray diffrac-tion (XRD), etc. It is found that the symbiotic relationship of iron, tin and zinc metallic minerals are very complicated, and magnetite in the concentrate is closely symbiotic or enwrapped by fine cassi-terite and sphalerite. So it is difficult to separate tin and zinc completely from the iron concentrates by simple regrinding and physical separation method. This investigation provides theoretical guid-ance for developing new approaches for utilizing these concentrates.

Jan 1, 2014

By Yongfu Yu, Xiaotie Wang, Fuguang Zhang, Liping Che

"The flotation process of native Rare Earth minerals such as bastnasite, monazite, mixed minerals of bastnasite and monazite, using the new effective collector Dh was studied in this paper, respectively, and the flotation properties are described. The good qualities of the new collector Dh were revealed through comparing with other collector of Rare Earth minerals. The test results of different ore samples show that at moderate pulp pH (8.5-9.5), Rare earth minerals can be effectively separated from barium, calcium and silicon bearing intergrowth minerals (barite, calcite and silicate minerals) and high quality Rare Earth concentrates can be obtained successfully by the new collector Dh, acid silica gel, turpentine and reagents fitting together rationally. In order to determine optimum technical conditions, the effect of pulp pH, pulp temperature, pulp density and the effect of dosage of reagents (Dh and acid silica gel) on the flotation were investigated in the test.Simultaneously, the paper explores the mechanism of the flotation of Rare Earth minerals from intergrowth minerals. The infrared spectra for Dh and Rare Earth cation by analysis in theory shows that Dh formed chelate complex with Rare Earth cation and were adsorbed on the surfaces of Rare Earth minerals. The mechanism of the intergrowth minerals depressed by acid silica gel can be explained as gummy colloid hydrolyzed from acid silica gel which are selectively absorbed on the gangue minerals, making them hydrophilic and depressed, with pulp pH value of alkalescent."

Jan 1, 2003

In this study, selective flocculating of diaspore using anion macromolecular reagent as flocculant was tested to separate diaspore from alum-silicate minerals. Firstly, the effect of pH on settling behavior of diaspore and kaolinite dispersions has been investigated. The results show that the maximum settling speed of diaspore and kaolinite appeared re-spectively at pH7 and pH3.33 which is close to the point of zero charge (PZC) of diaspore (6.8) and kaolinite(3.5). This result is in well agreement with the double electric layer theory. Secondly, the settling behavior of diaspore and kaolinite particles in different anion flocculant solution have been researched. The results indicate that flocculant solution concentration significantly affect the selectivity and the flocculating performance of anion molecular. In high concentration solution, both diaspore and kaolinite have faster settling rate compared to blank solution. How-ever, in low concentration solution, the anion macromolecular can enhance the settling rate of diaspore remarkably but has no apparent effect on the settling rate of kaolinite. This result suggests that the tested anion flocculant is a promising reagent for de-silica of diasporic bauxite. Lastly, FTIR method was employed to probe the adsorption mechanism of flocculant on diaspore and kaolinite. The results reveal that there are anion flocculant characteristic bands on the spectra of diaspore but no obvious characteristic bands of flocculant on the FTIR spectrum of kaolinite. This result is in good correspondence with settling test.

Jan 1, 2014

Electrochemical behaviors of synthetic and natural enargite in buffer solutions have been investigated using open circuit potential, stationary polarization and cyclic voltammetry as functions of solution pH, scan direction, scan range, scan rate and dissolved O2. The results indicate that the electrochemical behaviors of synthetic and natural enargite are very similar; solution pH, scan direction, scan range and scan rate have remarkable effects on the electrochemical behavior of enargite while dissolved O2 has little effect on the electrochemical behavior of enargite. The potential range in which enargite possesses the ability of passivation is from ?0.9 V to + 0.83 V vs. SCE. Enargite is most stable in neutral and alkaline solution around potential ?0.2 V vs. SCE. The main oxidation products on enargite surface in alkaline solution are Cu(OH)2 while the potential imposed on it is within the range of ?0.2 V to 0.33 V vs. SCE and Cu(OH)2 + S0while the potential applied is higher than 0.52 V vs. SCE.

Jan 1, 2014

By H. M. Yang

Structural alteration of pyrophyllite during mechanical activation in a planetary mill was investigated by X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) techniques. Mechanochemical effect markedly promotes the decrease in reflection intensities with increasing the grinding time. Prolonged grinding causes the pyrophyllite to become the amorphous structure. It can be indicated that pyrophyllite is very susceptible to alteration by grinding. Crystal size (d006) of pyrophyllite appears to be a limit after 2h grinding. IR spectroscopy analysis shows a little alteration in the bands of pyrophyllite after mechanical activation. The results indicate that the ordered structure of pyrophyllite is destroyed and lattice deformation occurs. Porous silica was then successfully prepared via leaching the mechanically activated pyrophyllite. Pyrophyllite was first ground for 6 h. Ground samples were subsequently leached with 4 M hy-drochloric acid at 80 °C for 2 h to produce porous silica with specific surface area of 188.1 m2/g, total pore volume of 0.18 mL/g and average pore size of 3.9 nm from N2 adsorption analysis. Otherwise, the porous silica obtained from direct leaching of the original pyrophyllite only has a specific surface area of 4.3 m adsorption analysis. 2/g and total pore volume of 0.03 mL/g. It is inferred that grinding is favorable for the formation of microstructure pores. It offers a simple and convenient route for the preparation of porous materials from natural minerals.

Jan 1, 2014

"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 P. Raghavan1

Reverse froth flotation experiments were carried out in the laboratory using two different types of kaolins for the separation and removal of coloring titanoferrous impurities from cryo-filtered clay after subjecting to high shear pre-treatment. This high shear pre-treatment consists of high shear agitation of a high solids clay slurry with the dispersant (high shear dispersion, HSD) followed by high shear agitation with the collector (high shear conditioning, HSC). After this pretreatment, the slurry is diluted and reverse flotation is carried out. One sample is from, Gujarat, India (Mamuara clay, ?MC?) while the 2nd sample is from Amberg, Germany (AKW clay, ?AC?). While MC consisted of 89% particles below 2µm and analyzed 1.06% of TiO2 and 0.29% Fe2O3 and measured a brightness of 83.4 %ISO, the corresponding values for AC are 67% below 2µm, 0.3% of TiO2? 0.49% Fe2O3 and 83.4 %ISO. The flotation performance is found to be greatly influenced by the conditions of high shear treatment. Important variables are HSD intensity (rpm), HSD time, HSC intensity (rpm), HSC time, HSD/HSC time ratio, ?HSD+HSC? total time etc. Higher shear intensities favor both the impurity liberation and collection. For both clays, it could be shown that impurity removal increases as total pretreatment time (?HSD +HSC? total time) increases up to a certain limit. For MC, the HSD time was only half or less than that of HSC time, while for AC, HSD time is at least twice (or more) than HSC time which is just an opposite manifestation. This is believed to be due to the striking differences between these two clays. Most importantly, the shear frequency is found more influential than the shear rate for the overall flotation performance for both clays. Interestingly, at high shear frequencies, i.e., when a stirrer with more number of teeth on the rotor is used, the ?HSD+HSC? total time is greatly reduced. Again, increased shear frequency helps to reduce flotation time and significantly improves flotation performance. At optimum conditions, product titania reduced to 0.35% for MC whereas the same reduced to 0.13% for AC. The product of flotation of MC measured 85%ISO brightness while that of AC measured84.6%ISO thus enhancing the value of the final product. It could also be established that the high shear pre-treatment shows better flotation performance than that due to collector dosage. Keywords: high shear dispersion, high shear conditioning, titanoferrous impurities, shear rate, shear frequency, brightness, clay recovery, Mamuara clay, AKW clay

Sep 1, 2012

By N. Schreithofer

Varying flow regimes, particle populations and consequently different types of bubble-particle interactions characterize the different zones of a flotation cell. The understanding of the role of the different zones of turbulent intensity on the particle-bubble interactions is of primary importance to optimization and scale-up of flotation processes and machinery. In order to study particle-bubble interaction in turbulent flow a completely new approach was taken. A laboratory scale stationary turbulence device was developed and built. The set-up allows the observation of particle-bubble interactions in various turbulence intensities, particle and bubble sizes and surfactant concentrations. The experimental set-up consists of a transparent, specially designed tank in which liquid flows between carefully designed and placed obstacles that create different turbulent flow fields. Bubble-particle aggregates are introduced into this turbulent zone. The behaviour of the aggregates, such as attachment /detachment of particles to/from air bubbles is recorded by a High Speed Imaging (HSI) system (5400 fps). The images are then analysed and the dependence of attachment/detachment process is described as a function of turbulent intensity in different conditions for different surfactant concentrations. This paper introduces this method to study particle-bubble interactions in turbulent flow and correlation to Computational Fluid Dynamics (CFD) simulation. CFD modelling is validated for two and three phase systems; liquid-gas with liquid and solid tracers respectively. The CFD simulations using the RANS k-S turbulence model showed good correlation to the experimental data and the experimental method is a promising tool for investigation of particle-bubble interaction in turbulent flow.

Jan 1, 2014

By B. Z. Wu

The ore dressing of tin-polymetallic lean ores is a difficult problem and the research emphasis in domestic nonferrous metals mining field. Through research and tackle key problem,and in order to supply reference in dealing with the same types ores, this paper expatiates the exploiture and appli-cation of six item new technology and technics in ore dressing of tin-polymetallic lean ores. It include the technics of multi-step compounding disposing tailings, grinding step by step, grinding and processing circularly technology, high thickness without circle flotation technology, dispersedly flotation tin step by step technology, exceed fine lean plumbum stibium zinc flocculation flotation technology, the synthetically recovery of waste water after ore dressing technology.

Jan 1, 2014

By E. Emelyanenko, P. Solozhenkin, J. Yagudina, O. Ibragimova

"To recover tetrahedrite-tennantite series minerals from porphyry copper-pyrite ores by the froth flotation method, further research on thiol collectors is launched to promote the utilization efficiency of copper ores. In the present paper the adsorption mechanism of the collectors on tennantite surface has been investigated by computational modeling and FTIR-spectroscopic analysis, which have revealed that the decrease in prognosis of collector activity evaluation (PCAE) for tennantite is in the following order: BX (-0.34318), AEROPHINE 3418A (- 0.61756), AERO 5100 (-14.18857). The lower PCAE the stronger the ability of the collector to interact with the mineral surface of tennantite and form the stable complex. More kinetic reliable conditions to form suitable adsorption layer and rupture of the liquid interlayer with AERO 5100 have been observed by FTIR spectra due to decrease of the intensity and stretching and bending vibrations of water (less than 20 and 65%, respectively). In order to verify the feasibility of AERO 5100 as a collector the industrial flotation tests have been conducted. Flotation performance has improved significantly with the stadially grinding and preflotation of tennantite in intercycle copper flotation that allows to avoid desliming of the fragile mineral and minimize loss of Cu and As in tailings. The recovery of copper in copper concentrate increases by 3.9% with the grade maintained.INTRODUCTIONCopper is one of the first metals extracted and the main material of choice for different high-technology applications today. Currently 80% of the world's copper comes from copper sulfide ores. However, due to the depletion of high-grade copper ores in the world and constantly growing demand for copper, the need to develop processes and technologies to treat copper resources from additional sources such as mine tailings, low grade deposits, industrial wastes and deposits with high impurity levels such as As and Sb will continue to increase (Miller and Craig, 1983). The beneficiation processes of copper-pyrite ores consisting of tennantite-tetrahedrite series minerals are generally complex. Tetrahedrite-tennantite minerals occur as fine anhedral grains intermixed with grains of galena, sphalerite, chalcopyrite, pyrite and other sulfides (Saharova, 1966). The mineralized zones of Southern Urals, Russia deposits correspond with these ore types but tennantite-tetrahedrite series are more abundant in ores at the Uzelginskoye deposit, some samples of which contain 70% of copper in tennantite form (Seravkin et al., 1994). This deposit differs from other similar copper-pyrite ores by thin mutual ""germinating"" minerals and higher content of arsenic (up to 0.8-1 %) which create additional considerable problems in enrichment (Solozhenkin et al., 2016)."

Jan 1, 2018

By E. Emelyanenko, P. Solozhenkin, J. Yagudina, O. Ibragimova

To recover tetrahedrite-tennantite series minerals from porphyry copper-pyrite ores by the froth flotation method, further research on thiol collectors is launched to promote the utilization efficiency of copper ores. In the present paper the adsorption mechanism of the collectors on tennantite surface has been investigated by computational modeling and FTIR-spectroscopic analysis, which have revealed that the decrease in prognosis of collector activity evaluation (PCAE) for tennantite is in the following order: BX (-0.34318), AEROPHINE 3418A (- 0.61756), AERO 5100 (-14.18857). The lower PCAE the stronger the ability of the collector to interact with the mineral surface of tennantite and form the stable complex. More kinetic reliable conditions to form suitable adsorption layer and rupture of the liquid interlayer with AERO 5100 have been observed by FTIR spectra due to decrease of the intensity and stretching and bending vibrations of water (less than 20 and 65%, respectively). In order to verify the feasibility of AERO 5100 as a collector the industrial flotation tests have been conducted. Flotation performance has improved significantly with the stadially grinding and preflotation of tennantite in intercycle copper flotation that allows to avoid desliming of the fragile mineral and minimize loss of Cu and As in tailings. The recovery of copper in copper concentrate increases by 3.9% with the grade maintained.

Jan 1, 2018

By Elisabeth Schmidt

The conventional Canadian oil sand processing, the Clark Rowe process, is associated with many risks for the environment and high energy costs. To recover the bitumen from the oil sand (tar sand), large quantities of water have to be heated up and mixed with caustic soda and the oil sand. During this process, tailings with stabilized clay colloids are formed and dumped in tailings ponds. To avoid these disadvantages, a new, non-aqueous extraction process is to be established. Organic solvents are used instead of water and caustic soda to mobilize the bitumen from the sand-clay mixture. Pressure filtration, washing and steam pressure filtration are part of the new concept. A mixture of organic solvents and the oil sand is first pressure filtrated in a nutsch filter until a saturation level of one is obtained. After the cake has been formed, the filter cake is washed with organic solvent to flush the bitumen loaded solvent out of the cake. The following steam pressure filtration mechanically and thermally removes the remaining volatile components of the solvents from the filter cake. The filtrates from the pressure filtration, the washing phase and partly from steam pressure filtration are subsequently thermally treated to recover the organic solvents and obtain a higher bitumen concentration in the mixture. This mixture is then lead to an upgrader to win synthetic crude oil (SCO). The recovery of bitumen in the conventional hot water extraction process based on the Clark Rowe process can, in highly optimized plants, achieve between 88 and 92 %. Variation of oil sand properties leads to an actual range of between 80 and 90 % of bitumen recovery. With the alternative process based on organic solvents, the bitumen recovery exceeds the recovery of the conventional process by up to 16 percentage points. The composition of the two organic solvents in the first step of forming a suspension with the oil sand is important. The aromatic component is crucial for liberating and solving the asphaltenes, which tend to flocculate. The order of the two components of organic solvents is also important in the washing step. The paraffinic component is essential to achieve successful steam pressure filtration with respect to fast steam breakthrough and a filter cake free from organic compounds, as a result of its lower boiling point. Keywords: oil sand, filtration, organic solvents, pressure filtration, steam pressure filtration, filter cake washing

Sep 1, 2012

By Y. Rama Murthy

Around 90% of the chromite resources of India are concentrated in the Boula-Nuasahi Sukinda belt of Orissa state. In order to conserve these valuable ore resources strategically, several companies established chrome ore beneficiation plants in this region. The general beneficiation process in these plants consists of gravity unit operations such as Floatex density separator, spiral, wet shaking table etc. Most of these gravity circuits suffer huge losses of valuable minerals in the tailing. Any attempt towards decreasing these losses would not only increase the limited reserves in India but also make the economics of the operations more attractive. Apart from the liberation phenomena, in many of the operating plants considerable quantity of values are lost in the tailings, due to inconsistent feed quality, inappropriate selection of operating and design parameters. Mineral engineers in this regard have to play a proactive and continuous role to improve the performance of all separating units by modifying even small changes based on tests conducted in laboratory under controlled conditions followed by attempts to make necessary changes in the plant. For such improvements, accurate data collection and proper data interpretation followed by making necessary change which is implementable in an operating plant play a very critical role in performance of the circuit. Databank collected over a period of time under various conditions would also help in overcoming the future problems related to either variation in the feed characteristics or specific demand by metallurgical industries. The above concept was adopted in one of the operating chromite beneficiation plant at Sukinda. The approach adopted and practical problems encountered during the study were reported in this paper. The result of trial campaign has shown that, an overall product assaying 30.2% Cr2O3 from the feed (18% Cr2O3 ) can be produced to in single stage. The final discards of the process contain 12% Cr2O3. Keywords: chromite, chromite beneficiation, chromite losses, gravity concentration techniques, plant operating data bank

Sep 1, 2012

By S. N. Shahcheraghi

Grinding is one of the most important and expensive steps in mineral processing allocating about 70% of the total energy in the plants. Nowadays, for optimizing the energy consumption in these equipments, the rock behavior and its size distribution during the crushing have been normally predicted using selection and breakage functions to be able to optimally model and design grinding circuits. For this purpose, the case of Miduk copper mine in Kerman province, Iran was studied. The samples were taken from primary ball mills feed and were subject to screen analysis to achieve uniform sizes. Then, selection and breakage functions were determined at the different grinding times in laboratorial ball mill. Finally, ore size distribution in different grinding times was estimated using MATLAB software

Sep 1, 2012

By Yuexin Han

The wet preconcentration of haematite, comminuted by high-pressure grinding roller was studied, using the cylindrical ferromagnetic medium. The effects of various factors including rod diameter, rod gap and background magnetic field intensity (BMFI) on the performances of preconcentration for different size fractions and the force analysis of single mineral particles with different diameter in the separation zone were emphatically investigated. The results showed that as the rod diameter increased, the rod gap decreased, and the BMFI increased the tailings grade and the tailings yield reduced while the concentrates recovery raised that was regardless of variations in feed size distribution. For the -3.2+0.18mm size fraction preconcentration, the magnetic medium with a rod diameter of 4 mm and a rod gap of 7 mm at BMFI of 454kA/m is used to get a higher performance. For -0.18mm size fraction preconcentration, the magnetic medium with a rod diameter of 4 mm and a rod gap of 4 mm at BMFI of 263kA/m is used to get a higher performance. After the classifying preconcentration, at the optimum condition, the overall concentrate grade increases by 9.56 percentage points and the concentrate recovery is up to the 82.67% with a tailing grade of 10.68% and a tailing yield of 40.31%. The magnetic force, exerted on weekly magnetic minerals was proportional, to the specific susceptibility and square of BMFI. For the same BMFI, the magnetic capturing force on coarse particles increased, and that on fine particles decreased with the increasing of rod diameter. For the lean locked-particles, considering the gravity and viscous resistance of particles, rods with a big diameter were beneficial to the capture of coarse particles and had no influence on the capture of fine particles, while rods with a small diameter were good for the capture of fine particles and not suitable for the capture of coarse particles of lean locked-particles. Keywords: low grade haematite, high-pressure grinding roller, high intensity magnetic separation, pre-concentration

Sep 1, 2012

By G. J. Mei

Separation of hematite and iron-containing silicate gangue - aegirine by Flotation using fatty acid collector and (NH4)2SiF6 depressant was investigated in this paper. The flotation tests with single minerals show Ammonium hexafluorosilicate (AHFS) is a selective depressant for aegirine in hematite flotation in weakly acidic medium, which can strongly reduce the flotation recovery of aegirine in the pH range of 4~5 while has no evident effect on the flotation of hematite. The results of flotation tests with actual ores show the separation of hematite from aegirine gangue by forth flotation was possible, and good selectivity was achieved. Chemisorptions were observed on aegirine mineral surface treated by AHFS solution by using SEM and IR spectrum measurements. On the basis of coordination chemistry, a comprehensive mechanism, which reasonably explains the selective depression of AHFS for iron-containing silicate, is also proposed.

Jan 1, 2014

By Mohsen Hashemzadehfini

Nowadays heap leaching has become established as a mineral processing technology for treatment of some low grade minerals such as copper, gold, and zinc, etc. Heap height, particle size, leach reagent consumption, and metal recovery are four important metallurgical parameters in a hydrometallurgical process like heap leaching. This paper investigated the effects of heap height and particle size on copper recovery as well as acid consumption. Three heap heights of 2, 4 and 6 meters and two particle size fractions of less than 25.4 mm and 50.8 mm were selected as variables in the experiments. The research results showed the inverse relation between heap height and copper recovery as well as acid consumption. Under given conditions, the copper recoveries of minus 25.4 mm ore are 78.63%, 66.27% and 52.88% higher than that of minus 50.8 mm samples for the heap heights of 2, 4, and 6 m, respectively. Both copper recovery and acid consumption increase with decreasing particle size. Keywords: heap leaching, heap height, particle size, acid consumption

Sep 1, 2012