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By M. Saghaeian, R. Hejazi, A. Dehghani Ahmadabadi, M. Zare

"In the most iron ore beneficiation plants, reverse flotation is the best method for removing silicate gangues from final iron ore concentrate. Many previous studies show, if the major portion of impurities include quartz minerals, the flotation process is simple, but if iron silicates are dominant, reverse flotation is so complicated and mostly not very effective. In this study which was performed on the Sangan iron ore concentrate, the performance using of reverse flotation and magnetic flotation separator for elimination of silicate gangues from the magnetic iron concentrate was investigated. The operational parameters for reverse flotation are considered as: collector and frother types and dosages and also modifiers. But for magnetic flotation separator parameters were magnetic field intensity as well as overflow and underflow water rates. Results showed that reverse flotation has not a significant effect on the elimination of impurities. Because of the silicate gangues of Sangan concentrate including a mixture of quartz and iron silicates (amphibole, pyroxene and feldspar), so downgrading of the SiO2 content for the flotation concentrate was rather low and only average reduces of 20.60% were possible. But the findings of using magnetic separator was more satisfactory. Results of the weight recovery, iron grade and also SiO2 and S grades of final concentrate were better with magnetic flotation device. So at the best and optimum condition, we could reduce 51.01% of the total silicate (SiO2~ 2.19%) along with 74.66% of sulfur content (S~ 0.076%) and concentrate weight and Fe recoveries of 92.04% and 94.51% respectively, final Fe grade of 68.73%.INTRODUCTION Chemical/traditional flotation is one of the most effective methods for separating valuable particles from waste minerals, which is used in most mineral processing industries. In the iron ore processing industry, the major impurities present in iron ore concentrate include sulfur, silica and phosphorus (Bruckard et al, 2015), which are often carried out by reverse flotation methods for the removal of sulfide and oxide impurities (Donald, 1967: Araujo et al., 2005: Ma, 2012)"

Jan 1, 2018

By Abhilash

Different methods of utilizing refractory bauxite and disposing red mud are practiced throughout the world, but none of them are known to be environmentally innocuous due to the complexity and /or high cost, and none has been found to be feasible on an industrial scale. Under these conditions, the use of bioleaching process seems promising. The present study emphasizes on the isolation of native extremophiles from the source Indian bauxite and red mud, with their detailed cellular and physio-chemical, and biochemical characterization. These organisms were tested for their ability to thrive in physically or geochemically extreme conditions. The gram positive capsule rich mesophiles and thermophiles were tested for removal of gangue minerals from the bauxite and red mud samples. Keywords: refractory bauxite, red mud, extremophiles, bio-beneficiation, gangue

Sep 1, 2012

By C. Igathinathane

Coal is the most widely used fossil fuel in the world, providing more than 25% of world?s electrical power. Since, the behavior of coal particles in crushing and grinding circuits, concentration operations, and solid-liquid separations is strongly dependent on size, a reliable and accurate measurement of particle size and particle size distribution (PSD) is a vital aspect in coal cleaning. This paper presents a method for the characterization of ground coal particles using image analysis. We utilized a machine vision (MV) approach that used a document scanner as the imaging device and a user-coded ImageJ plug-in that processed the image and automated the PSD analysis and output results in textual and graphical forms. This approach used a sum of volumes (SVolume) as weighting factor for particle length as the primary dimension of analysis and was successfully applied to ground coal. The plug-in was further improved for computational performance in this study. Mechanical sieving (MS) was also used to compare the MV results. MV results showed that the PSD of ground coal followed a uni-modal normal distribution, and the log-normal plot against particle size exhibited a linear trend for most of the range. MS results, however, had three linear segments, when the width-based sieving results were transformed to lengths by applying the shape factor (width/length), but a definite deviation between the PSD plots was observed. This study demonstrates successful application of the MV SVolume approach for PSD analysis of ground coal, which can be extended to similar particulate minerals and products. Keywords: dimension, fiji, image j, image analysis, coal, particle size, plug-in

Sep 1, 2012

By Dmitriy Kim, Natalya Ibragimova, Galina Sedelnikova

Gold and copper are lost in flotation tailings in mineral processing of copper-zinc-pyrite ores. Large resources of precious and base metals have accumulated in tailing ponds of Russian plants. Object of the study is the sample obtained from Ural Mining and Metallurgical Company in Russia. The main constituents in flotation tailings are Au, Ag, Cu and Zn with content 1.4 g/t, 12 g/t, 0.66 and 0.5% respectively. The flotation tailings are a refractory material. Gold, as main metal, is fine encapsulated in sulfides, mainly in pyrite. Gold extraction from tailings is 34.0 and 42.7% at P42 and P90 of 0.074mm particle size respectively. In this work heap bioleaching of tailings was studied for oxidation sulfides (pyrite and chalcopyrite) with using mesofilic and moderately termofilic bacteria in acidic solutions. The tailings had low filtration property (< 0.3 m/day) and pelletization was used before bioleaching. Copper containing converter slags flotation tailings and calcium oxide were used as binding material for increasing filtration property of tailings. Copper was extracted in sulfate solution and was precipitated by cementation after cleaning of bacterial solution from iron. Copper recovery was 56.8% at content 61.4% in precipitate. The biooxidation of pyrite was 80%. Cyanidation, leaching with thiourea and heap leaching by cyanide were tested too. Gold extraction from solid bioresidues was 82, 75.3 and 77% respectively. The results of this investigation were recommended for pilot test.

Jan 1, 2014

By A. Ghadyani

This investigation was undertaken to assess the possibility of ash and sulfur removal by microbial action of high sulfur-content coal. Thiobacillus ferrooxidans and Thiobacillus thiooxidans have been used for biodesulfurization of coal. Feed samples were provided from Tabas coal mine located in Yazd province, Iran. The sample contained 28.80% ash and 2.30% sulfur. Flotation tests were implemented to optimize the effective parameters in these cells which were constant during bio-flotation tests. According to the results, obtained from various tests using Taguchi orthogonal array design (L27), the values of optimized parameters were pH at 7, 1000 g/t gas oil as a collector, 10% solid content, 15 min conditioning time, 100 g/t MIBC as a frother and 800 rev/min rotor speed. Bio-flotation tests are carried out by means of laboratory double discharge cell and mesophilic bacteria as depressant reagent using above mentioned optimized parameters. The bio-flotation experiments were conducted based on a Taguchi orthogonal array design (L9) with four variables (bacteria type, bacteria count, rotor speed of mixer and bio-conditioning time). The collected data was analyzed by using DX7.0, Minitab14.0 and WinRobust1.02 softwares for evaluation the effect of each parameter on the optimization criteria. Considering the highest combustible recovery and the lowest ash and sulfur content, the value of optimized bacteria type, bacteria count, rotor speed of mixer and bio-conditioning time were Thiobacillus ferrooxidans, 5×107 cells/g(coal), 100 rev/min and 20 min respectively. Under this condition, ash and sulfur content and combustible recovery were predicted 12.39%, 2.08% and 82.03% respectively.

Sep 1, 2012

By Benoit Clermont, Jan Lux

"Magotteaux and Anglo Platinum started a co-operation program with the main aim of establishing the optimum milling configuration measured in terms of throughput, fineness and energy consumption.For this purpose, a fully instrumented pilot milling plant, supplied by Magotteaux (Pty) Ltd, and equipped with a 0.9 x 1.0 m ball mill, was erected at Frank concentrator (Merensky Pt ore). The primary ball mills at Frank concentrator were surveyed in order to set the conditions for the base case. This data was then replicated in the pilot mill under the same configuration. Thereafter, a series of different parameters were varied in order to attempt to optimize the milling system.Some of the grinding parameters that have been studied are:•,Gate versus overflow discharge•,Open versus closed circuit•,Different filling degrees•,Different shell liner profilesOnly grate versus overflow discharge and open versus closed circuit will be discussed in this paper.It should be noted that this paper does not attempt to give a universal solution as to what milling configuration is optimum in all cases. The conclusions apply for this particular case and probably most others, but it would be advisable to consider each case on its own."

Jan 1, 2003

By M. Brozek

The constant of flotation velocity is the value characterizing the kinetics of cyclic flotation. In the statistical theory of flotation its value is the function of probabilities of collision, adhesion and tearing off the grain from the air bubble. The grain ? air bubble collision plays a key role since there must be a prior collision before the grain ? air bubble adhesion happens. The probability of such an event to occur is proportional to the relation of the grain diameter to the bubble diameter. When the grain sizes are given, it is possible to control the value of collision probability by means of the size of air bubbles. Consequently, it is significant to find the effect of physical and physicochemical factors upon the diameter of air bubbles in the form of a mathematical dependence. In the pneumo-mechanical flotation machine the air bubbles are generated by the blades of the rotor. The dispergation rate is affected by, among others, the rotor rotational speed, the amount of air transported to the flotation chamber an time and the liquid surface tension, depending on the type and number of applied flotation reagents. In the proposed paper the authors will present the distribution of air bubble diameters on the grounds of the above factors, according to the laws of thermodynamics. The correctness of the de-rived dependences will be verified empirically.

Jan 1, 2014

By M. Saghaeian, R. Hejazi, M. Mohammadinejad, M. Zare

"Water quality and quantity at the Tailing Thickening Section of processing plants is considered to be a crucial factor and impacts the performance of several sections. Therefore, gaining stable and effective performance at the Tailing Thickener Section is one of the principal goals of minerals processing plants. Different factors such as: qualitative and quantitative sustainability of plant feed, the balance between the mass of input and output water flow, the dissolving method and distribution of flocculant and the amount of dirt, solid percent of thickener inlet pulp, affect the performance of Tailing Thickener. The present study investigates the successful improvement of Tailing Thickener performance at Jalal Abad Hematite Iron Ore Concentrate plant through optimizing the above operational parameters. For this purpose, the following optimizations have been done: homogeneity and sustainability of plant input feed rates, fine pulp removal collected by the bag filters at the input of the thickener, adding an quietness box before moving the tail pulp into the thickener to reduce the pulp turbulence, replacing flocculant pump and injection pipes, improving water mass balance which leads to optimizing and stabilizing the concentration of input tail pulp into the thickener, adding a mixer to increase the flocculant preparation time, increasing the locations for adding flocculant to thickener from 1 point to 6 points. Applying the above modifications and monitoring the Tailing Thickener performance over the course of months, has led to the improvement of recovered water quality from 500 ppm to 200 ppm, increasing the solid underflow of the thickener from 40% to 48.5%, and similarly, reducing water loss by 60%. Of other important effects, due to improvement of water quality, grade of final concentrate 0.5% increased and because of 73% increase in monthly working hour, concentrate tonnage 55% increased. Finally, sludge thickener optimization has had a significant effect in selecting and designing the dewatering system from the underflow of the sludge thickener."

Jan 1, 2018

By Zhangm Zeqiang, Manman Lu, Hanquan Zhang, Hong Yu, Jintao Fu

"Pelletizing is an important technique in the ironmaking industry. Artificial and natural magnetites are materials that are widely utilized in the iron ore pelletizing process. In this work, the pelletizing characteristics of these two types of magnetite have been investigated in detail. The obtained results shown that in contrast to natural magnetite, the artificial magnetite concentrate exhibits stronger hydrophilicity, lower electronegativity, larger specific surface area, and rougher surface. In addition, the green pellets produced from the artificial magnetite concentrate are characterized by a higher compressive strength as compared to that of the pellets obtained from the natural magnetite concentrate. However, the shock temperature of the artificial magnetite pellets around 255 C is significantly lower than the threshold specified by the industry. The balling characteristics of the material obtained by mixing 20% of the artificial magnetite concentrate with 80% of the natural magnetite concentrate are considerably improved with respect to those of the individual components.INTRODUCTION Pelletization is an essential process of the ironmaking industry in China. Since the pellets produced from iron ore exhibit high mechanical strength, good particle granularity, and uniform shapes, pelletizing high-grade iron ores with good metallurgical reducibility can lower the coke ratio, improve their technico-economic index, and reduce the cost of processing pig iron in blast furnaces[1, 2]. Presently, high-grade magnetite is a material utilized for pelletizing various iron ores across the globe. However, its natural deposits have been depleting rapidly in recent years; as a result[3], China’s dependence on the foreign high-grade iron ores exceeded 70% in 2009 and reached the level of 87% in 2016. Hence, possible methods for the efficient cultivation of limonite, siderite, hematite, and other refractory minerals that correspond to low-grade, finely sized, inhomogeneous, and scattered iron ores have attracted significant attention [4, 5]. In particular, magnetization reduction roasting and magnetic separation techniques, which are widely utilized for obtaining high-grade artificial magnetite, represent effective ways of processing iron ores that can alleviate the scarcity of natural magnetite resources [6, 7]. The artificial magnetite produced by magnetization reduction roasting exhibits different characteristics as compared with those of natural magnetite (including the degree of hydrophilicity, surface potential, specific surface area, and other surface physicochemical properties[8-11], which significantly affect its pelletizing behavior. In this work, the surface characteristics of artificial and natural magnetites are investigated in detail, and their effect on their pelletizing properties (such as green ball strength, heat stability, and pelletization rate) are examined."

Jan 1, 2018

By Graeme Heyes, Warren J. Bruckard, Michael A. Somerville

"A limited series of laboratory batch flotation tests was conducted on a suite of calcium-ferrite-based slags made in laboratory smelting trials. The smelting tests were conducted as part of a wider CSIRO Minerals’ research project aimed at developing a single-stage continuous copper-making process. The objective of the flotation work was to maximise copper recovery and iron rejection from slags made in the process.The slags treated included a reduced low copper slag, an oxidised high copper slag composite, and a very reduced low copper self-pulverising slag. The copper content of the slags varied from 2.9% to 14% Cu. The copper was present as metallic copper, oxide copper and copper-calcium ferrite phases with the phase mix related to smelting conditions. The slags were crushed, ground, wet-screened at 355 or 210 µm to remove coarse metallic particles of copper, and floated at natural pH (about pH 11) using reagents and conditions appropriate for the selective recovery of the copper phases.In rougher/scavenger tests on the reduced low copper and self-pulverising slags copper recoveries above 92% were obtained with copper enrichment ratios varying between 2.3 and 2.9. For the oxidised high copper slag copper recoveries were poorer - only 47% of the copper was recovered with an enrichment ratio of 3.3. The presence of the slow floating copper-ferrite phases in the slags limited further (selective) copper recovery. Ageing of the high copper slag, that is, a significant delay between grinding and flotation, resulted in a deterioration of the copper flotation response.The critical parameter affecting the flotation of copper from direct converting slags was found to be the form of the copper in the slag. Slags containing a higher proportion of the more desirable form of copper for flotation will provide the best opportunity for high copper recoveries to be consistently obtained, allowing improvements in the economics of the overall copper-making process."

Jan 1, 2003

By John Jiang, Brian R. Hart, Stamen S. Dimov, Aparup Chattopadhyay, Barun K. Gorain

"This paper presents a systematic approach to metallurgy diagnostics using an integrated gold deportment methodology developed for complex refractory gold and copper-gold ore bodies. Quantification of gold deportment for these ore bodies is a challenging task due to reasons such as lower grades, high variability of visible and invisible gold content in different sulphides and iron oxide phases, significant presence of disseminated and composite carbonaceous matters along with associations of various copper sulphide phases. Some case studies are presented in this paper to demonstrate the value of a high confidence gold deportment methodology in developing insights for problem diagnostics and to identify opportunities for metallurgical improvements. A holistic approach involving different fields of expertise is critical for successful development and delivery of solutions for complex ore bodies.INTRODUCTION Studies were initiated on various ore complex ore and also on samples representing various process streams. These complex copper-gold single refractory, double and triple refractory gold ores are mainly composed of silicates and/or carbonates with moderate amounts of clay and mica, along with minor amounts of sulphides and organic carbonaceous matter. Variable proportions of visible gold and “invisible gold” (sub-microscopic gold) were noted in different mineral phases for various ore types and process stream samples. Invisible gold commonly occurs as solid solution or as colloidal-sized particles in different sulphides (pyrite, arsenopyrite, pyrrhotite, chalcopyrite and galena) and other phases (including hematite, magnetite and goethite) for different refractory ores. The dominance of invisible gold and presence of highly preg-robbing along with finely disseminated carbonaceous matters adversely affects gold recovery in flotation and leach circuits for most of these double and triple refractory ores. This paper discusses applications of an integrated gold deportment technique developed for different types of gold and copper-gold ores, namely, complex copper-gold, double and triple refractory gold ores (Chattopadhyay and Gorain, 2014; Chattopadhyay et. al., 2016). Various process streams from flotation and gold leaching circuits were investigated. Different concentrates and tailings samples from flotation circuits whereas feed and discharges from pressure oxidation (POX) and carbon-in-leach (CIL) residues were used from gold processing circuits."

Jan 1, 2018

By Ritva Tuunila, Antti Häkkinen

"Wet stirred milling is one of the most effective grinding methods in producing very fine powders in large scale production, but it is a very energy-intensive process, especially when pigments or even nanosize particles are produced. Therefore, optimization of the process parameters is important. The specific energy consumption is a function of stress energy, which describes the effect of tip speed and media characteristics on grinding, and is related to the number of stress events during milling. In effective grinding, a large number of stress events are necessary. The stirrer configuration influences the number of stress events and their intensity, because the motion of the media and the suspension are caused by a rotating stirrer. The effect of three different stirrer types: a pin, disc and blade stirrer, on the grinding rate, i.e. product fineness and specific energy were investigated in this study with a batch laboratory stirred mill with two tip speeds. The material used in the experiments was calcium carbonate. The results obtained with the smaller tip speed showed approximately similar grinding rates and energy consumption for all stirrer types. When looking in closer detail, the blade stirrer seemed to give the finest product with all grinding times compared to the pin and disc stirrers, which both produced almost the same product fineness with the same grinding times. The specific energy consumption was the smallest with the disc stirrer, but not very big differences were obtained. With a higher tip speed, greater differences occurred both in grinding rates and specific energy consumption. The blade stirrer was the most effective in grinding, and the pin stirrer the next. The net energy consumption for the blade and pin stirrers was almost the same, but it was slightly higher for the disc stirrer."

Jan 1, 2014

The present study is devoted to improvement of the leaching efficiency during phosphorous removal from high phosphorous gravity-magnetic concentrate. Before leaching the concentrate has been subjected to roasting with the addition of either Ca(OH)2 or CaO. The oolitic iron ore is roasted at 900°C for one hour. This reflects in reaction between alkaline earth additive and quartz, aluminosilicates, phosphorus, and some other minor components of the gangue minerals. The application of leaching, physical separation, and wash out of salts has resulted in the decrease of phosphorus from 0.7 to 0.15 % and it is established that the major influencing factor is the concentration of acid and to a less extent duration of the leaching process. About two third of the phosphorus can be removed by roasting with 3 % CaO to hematite, coarse grinding to d50 0.3 mm, dry high intensity magnetic separation and leaching of the magnetic fraction with hydro-chloric or nitric acid.

Sep 1, 2012

By L. Pan

As an air bubble approaches a mineral surface, a thin liquid film (TLF) is formed in between. The excess pressure (p) in the film determines the kinetics of drainage, which is of critical importance in flotation. We have developed a new method of monitoring the kinetics for both stable and unstable wetting films and analyzed the results using the Reynolds lubrication theory. It has been found that initially a TLF is thinned by the Laplace pressure (pcur) due to changes in bubble curvature and subsequently by the disjoining pressure (?) created by the surface forces present in a wetting film. In the present work, we have derived an analytical expression for determining ? from the temporal and spatial profiles of TLFs on mineral surfaces. The results show that ? > 0 in a film formed on a hydrophilic surface and ? < 0 in a film formed on a surface hydrophobized by collector. Thus, the role of collector in flotation is to create a hydrophobic force and hence a negative disjoining present in wetting films. It is also found that smaller bubbles can create higher Laplace pressure, which helps the TLF drain faster.

Sep 1, 2012

By Aline Tavares

This paper describes the investigative studies carried out at Vale´s Center of Mineral Development (CDM) for a nickel sulfide deposit aiming to develop an adequate flotation flowsheet. The CDM facilities comprises of very well equipped laboratories to develop hydrometallurgical, comminution, flotation, physical separation processes, besides chemical and mineralogical laboratories, that are required to accomplish pre-feasibility studies, new process routes developments and, eventually, brownfield projects. Close association of the flotation group with the geometallurgy and the mineralogy teams play a key role during greenfield project development. Most of the information required by process engineers responsible for the flowsheet development can be provided by the mineralogy team and its mineralogical laboratory at CDM. During the flowsheet development of this nickel sulfide deposit, two ore types were identified as the most abundant in the deposit, named biotite-chlorite hydrothermalite (HID) and magnetite hydrothermalite (MAG HID). Six samples were selected for the investigative studies based on this initial information. Nickel grade varied from 0.39% to 1.95%. The main nickel-bearing minerals were millerite and pentlandite whereas the main non-sulphide gangue minerals were quartz, plagioclase, biotite, chlorite, actinolite, and/or magnetite. Electron microprobe (EMP) identified the presence of nickel in solid solution in gangue minerals such as biotite, chlorite, and actinolite. Nickel deportment in silicates varied from 3% to almost 40%. Magnesium was distributed in biotite and chlorite, except in sample MAG HID, in which talc was responsible for almost 50% of the Mg content. Liberation studies indicated that the optimum feed grind size was around 150µm and that pyrite occurred highly associated to the nickel sulfides. The flotation tests were planned based on the information provided by the mineralogical data. Rougher flotation tests indicated that the optimum P80 of the primary grind was 212µm for the HID type and 150µm for the MAG HID. From the reagents tested, amyl xanthate proved to be the most efficient in the recovery of the sulfides. In the MAG HID sample talc was well depressed by dosing 600g/t of CMC. Nickel recoveries in the rougher stage were lower than 90% due to the nickel distributed in silicates. However, sulfur recovery was around 95%, indicating high recovery of the total sulfides. Open circuit and locked cycle tests were conducted to evaluate the effect of the regrind size in the nickel grade and recovery (P80 of 44µm and 20µm). Nickel recovery decreased from 70% to 65% when finer regrind size was tested. Although nickel recovery decreased by 5%, the finer regrind size lead to a higher Ni grade (from 11% to 23%Ni) and lower fluorine grade (from 1138ppm to 700ppm) in the concentrate. Keywords: nickel sulfide, flotation, mineralogical characterization, flowsheet development

Sep 1, 2012

By G. Atesok

Turkey?s EU affairs started in 1963 with the Ankara Treaty. On 31 December 1995 the Customs Union between Turkey and the European Union came into effect. In order to achieve the Copenhagen Criteria?s, Turkey, made laws parallel to the Framework Programs. On 3 October 2005, with the confirmation of ?Membership Framework Document? the negotiation process of Turkey has started. Coal had important role in the industrialization of EU and it is directly related to Energy and Environmental subjects. In this point many restriction became with the some protocols, in last decades. European Union composed Energy and Coal Policy, therefore engaged to reduce the emissions, and made new regulations. This regulations concern Turkey?s energy future, since large; but low quality of lignite reserves of Turkey, it is expected to have some difficulties with Union?s Environmental Legislation during Turkey?s congruity process. With the last natural gas import agreements of Turkey, the production and consumption of coal sunk in last seven years. However, considering environmental sustainability, the role of coal in energy production will rise up in the coming future. In this paper, in terms of Turkey Energy Sector, production and consumption problems of coal discussed and evaluated considering EU?s coal, energy and environmental rudiments.

Jan 1, 2014

By G. Demi

Chromium ore exploitation has commenced in 1948 in Albania and there are produced about 24.3 million tons up to the end of 2006. Last years the prices and need were increased notably. Main export of chromium ores and concentrates was accomplished respectively 114 500 ton and 13 000 ton in People Republic of China during 2006 year. Location, status, reserves and grade of chromium deposits of Albania are presented in the paper. Chromium ore enrichment is related with their composition and Cr2O3 content, as well as with market requests. Actually, high grade chromium ores with Cr2O3 content over 38% ~ 40% are directly exported or treated in metallurgy, but last time have been exported and chromium ores with 28% ~ 30% Cr2O3 content for the reason that dressing plants can not be operated for investment lack. High grade chromium ores have been treated in heavy media separation plant before 1990. It is presented flow sheet, figures and necessity to put in operation HMS plant in the paper. Actually, low grade chromium ores with content 16% ~ 20% Cr2O3 are not enriched for the lack of investments, but before 1990 they have been concentrated in dressing plants producing chromium concentrates grade 48% ~ 50% Cr2O3. In the paper are shown technological schemes and industrial figures during more than 20 years operation and possibilities to reconstruct these mineral processing plants. Only chromium mineral processing plant of Bulqiza is in operation using as raw material its old existing tailings. The flow sheet and figures show that are possibilities to increase recovery and grade of concentrate in the plant. Separation and concentration of slimes in suitable equipment gives visible improvement of Cr2O3 recovery. Several tests have been carried out with flotation and magnetic separation methods for enrichment of low grade chromium ores. Flow sheet and figures of mineral processing ores content olivine as gangue mineral are interesting, because combination of gravimetric with magnetic methods is necessary in this case. In the paper are presented the tests and good results of low chromium ore pre concentration. Metallurgical treatment of chromium ores to produce Ferro chrome, as well as technological process, figures, consume of electrical power and materials in Elbasani and Burreli furnaces are shown and necessary investments to treat in metallurgy all produced chromium ores in Albania are considered.

Jan 1, 2014

By Fiona Sofra, Briony C. Ruse, David B. Boger

"The sustainability of the mining industry must be addressed through improving tailings management. The use of thickened tailings and pastes stems from a paradigm shift towards designing tailings disposal sites to suit their surrounding environment, rather than manipulating the environment to accommodate the tailings. Thickened tailings and pastes usually exhibit non-Newtonian behaviour, so a thorough understanding of the rheological characteristics of the material is required in order to determine the disposal plant operating conditions.Full Cost Accounting techniques may be used to provide financial justification for the implementation of alternative tailings disposal techniques through the calculation of a disposal cost per tonne of tailings over the life of the facility. Improved disposal methods such as thickened tailings disposal involve additional initial capital expenditure but reduce environmental impacts. The cost savings associated with environmental impact mitigation are reflected in Full Cost Accounting outcomes.Rheological characterisation is significant as a design basis that may be analysed using Full Cost Accounting to justify the initial capital expenditure of dry disposal systems for improved environmental performance."

Jan 1, 2003

By X. Q. Ma

The beneficiation test on low grade phosphate ore from a state of Russia is carried out. The rougher-cleaner ? re-cleaner system is used in the flotation process, The fineness of grind is 39.07% minus 200 mesh. The result indicates that concentrate containing 31.25% P2O5 can be obtained from the flotation feed assaying 6.18% P2O5, with 93.54% P2O5 recovery. The test result is also a guideline for further development of some currently operated phosphate beneficiation plants.

Jan 1, 2014

By G. Prabhulingaiah, D. M. R. Sekhar

"A phosphate deposit of estimated 6 billion tons of P2O5 is located 180 to 300 meters below the sea level, 185 kilometers north of port Luderitz, Namibia. The ore bed is 6 kilometers wide and 220 kilometers long. The ore deposit analyzing 16% P2O5 is loose sediment of 1.5 meters thick without over burden. Sizing of the ore to - 1.4 mm + 0.150 mm improves the grade to 23.54% P2O5 with a P2O5 recovery at 83.75% containing phosphate pellets and flakes of sea shells. Clay, bacterial debris as organic matter, flakes of broken sea shells and fine phosphate containing particles report to - 0.150 mm fraction and + 1.4 mm fraction contains sea shells and few phosphate containing pellets. The mineralogical composition of phosphate containing pellets is estimated (Droste, T.C., 2004) 80% frankolite, 6% pyrite, 4% illite, 3% quartz, 3% amorphous SiO2, 1% carbonates, 1% organic carbon and = 1% ilmenite, magnetite, zircon etc. The phosphate content in the pellets is around 27.7% P2O5. Trials to separate by gravity or flotation processes were not successful. Leaching of carbonates (sea shell flakes) under mild acidic condition (= 2% acetic acid or HCl solutions) or calcinations followed by leaching however yielded residues (concentrates) of grades 27.85 - 32.74% P2O5 at P2O5 recoveries ranging from 78.45 - 96.8% P2O5."

Jan 1, 2014