Search Documents

By Neill Bartie, Jacques Eksteen, Sharif Jahanshahi, Shouyi Sun

The gradual increase in Cr2O3 levels of UG-2 ores has become a matter of concern for platinum producers in South Africa due to the formation of chromite spinels in melters. The effect of bulk FeOx/MgO ratio, Cr2O3, temperature and oxygen partial pressure on phase stability and composition in the system FeOx-MgOSiO2- Cr2O3-Al2O3-CaO has been studied between 1400°C and 1600°C using the drop-quench technique. An increase in temperature was found to result in a decrease in [Fe/Cr]spinel. An increase in bulk FeOx/MgO caused Mg, Al and Cr in spinel to decrease, forming more magnetite relative to other spinels. [Fe]spinel decreased and [Cr]glass increased with a decrease in oxygen partial pressure.

Jan 1, 2003

By A. V. Golovanov, A. V. Mihailova

"NPO RIVS employs complex approach to engineering and design of the new facilities in close cooperation of Mining, Research, Hydrometallurgy, Design, Construction, Power Supply, Automation, Production and other departments. General Design Contractor (and then General Contractor) is directly involved in geological exploration, engineering surveys, floatability studies, feasibility study of process solutions and construction options. It delivers greenfield project and guarantee its efficient performance in future. Shiralgin is a small gold and copper deposit, gold average grade is 4.7 g/t. RIVS departments have studied ore floatability, developed process procedures for design and performed pilot testing. Construction of integrated plant including ore crushing and grinding, flotation and hydrometallurgy units with Dore gold production of 5 000 thousand tons ore per year (66.7 t/h) is recognized as economically viable. The technology used of separate dry stockpiling of flotation tailings and cyanidation tailings. Water circuit for concentration and hydrometallurgy is separated, too. Process design was performed based on BIM software like Autodesk Revit, Civil 3D, Rocscience slide using process procedures developed by RIVS Research units. Engineers provided modeling of primary crushing unit, coarse ore storage, main building (including grinding, flotation, thickening, filtration, loading, hydrometallurgy), tailings thickening unit, building for reagent storage and conditioning, tailings pond for dry stockpiling of flotation tailings and cyanidation tailings, sedimentation ponds, laboratories, infrastructure including Administration building and camp. Payback period is 3.5 years. 3D model of facility is currently stored at the State Agency of Geology and Mineral Resources affiliated to the Government of the Kyrgyz Republic.INTRODUCTION The Kyrgyz Republic has substantial potential of mineral resources including gold ores. Mining industry actively develops and involves international investors. Inventory includes 42 deposits (Figure 1) that have reserves of 616.4 t [1] of gold. The Kyrgyz Republic takes the third place in gold mining among CIS countries after Russia and Uzbekistan by producing up to 20 t annually."

Jan 1, 2018

By Dingwu Feng, Jannie S. J. van Deventer

"The effect of ultrasonication on reactions at solid/liquid interfaces was investigated by using an ultrasonic probe in two slurry systems, i.e. cyanidation of a refractory sulphide ore and geopolymerisation of metakaolinite. The surfactant dithiophosphate was used to render the gold bearing sulphide particles hydrophobic, in an attempt to induce the formation of cavitation bubbles directly at the desired surfaces. Oxygen was injected into the cyanidation system to improve the attachment of oxygen bubbles to the hydrophobic sulphide surfaces. Geopolymerisation occurs in highly alkaline solution with waste aluminosilicate oxides and silicates as the reactants. The process of geopolymerisation is believed to involve dissolution of Al-Si oxides from solid particles, diffusion of dissolved Al-Si complex from the solid surface into the gel phase, condensation of gel phase and hardening of the gel phase. It has never been investigated how ultrasonication affects the above steps in synthesising geopolymers, despite a number of papers dealing with sonochemical synthesis of materials. The introduction of power ultrasound into such slurry systems is expected to result in advanced geopolymer materials.In the cyanidation of the pyrite concentrate, the kinetics of gold extraction were significantly enhanced in the presence of ultrasound, due to the prevention of passivation and the enhanced dissolution of sulphides. Cyanide consumption was significantly reduced with ultrasonication, owing to the oxidation of soluble sulphides to sulphate, minimising the cyanide consumption by sulphides. With oxygen injection, ultrasound significantly enhanced the leaching of gold from the pyrite concentrate, as oxygen could enhance the formation of the oxidation radicals by ultrasonic cavitation. In the presence of dithiophosphate, ultrasound further improved gold leaching in the oxygen-aerated system. Dithiophosphate could selectively adsorb at gold host sulphide surfaces, and make the surfaces hydrophobic. As a result, the ultrasonication effectiveness could be enhanced through forming cavitation bubbles directly at the interfaces."

Jan 1, 2003

By Zoran M. Stevic, Mirjana M. Rajcic-Vujasinovic, Zvonimir D. Stankovic

"Covellite is one of the most important copper sulfide minerals. Its behavior during the anodic polarization, as well as its rest potential in various solutions are of importance for flotation processes and also define the mechanism of electrochemical extraction of copper from sulfide minerals.Measurements of the rest potential have been performed in water solutions in presence of different cations and anions. The existence of the Nernst type dependence of the rest potential on the activity of some of the investigated ions was established. The biggest influence on the rest potential of covellite exhibits the change of activities of the ions forming the crystal lattice of investigated mineral, i.e. Cu(II) and S(II). The dependence of the rest potential of covellite on logarithm of Cu(II) activity has a shape of a strait line with a positive slope of 60 mV, while when concentration of S(II) anions increases ten times, the rest potential of covellite decreases about 120 mV. The first dependence was established in acid medium, while the second was registered in alkali one.Different electrochemical techniques have been used for the investigation of the behavior of covellite during anodic polarization. In the basis of all these measurements is a three electrode system consisted of: 1) working electrode made of the sample of natural covellite from the Bor mine (Eastern Serbia, Yugoslavia); 2) reference electrode (saturated calomel electrode) and 3) counter electrode (flat platinum). Electrolyte solutions used in these investigations are of the same kind as those used in the rest potential measurements. Sulfate and chloride solutions, as well as the mixed sulfate/chloride solutions, are the most perspective from the application point of view.Cyclic voltammetry has been the first used method that confirmed the formation of passive layer on the electrode surface during anodic polarization. Elementary data about the reaction mechanism have been obtained too. More detailed data needed for more precise conclusions about the mechanism and rate of the anodic process on covellite have been obtained by galvanostatic method. It was established that the essential difference exists between the reaction mechanism in sulfate and chloride solutions. Also, the difference is exhibited in the nature of reaction product directly connected with the passivation of the electrode surface. Chronopotentiometric investigations have been performed in sulfate, nitrate, chloride perchlorate and mixed sulfate/chloride solutions applying different current densities. The shape of obtained curves indicate if there was a surface passivation and how intensive it was."

Jan 1, 2003

By L. Weitkämper

The big challenge at present and in the future is the economization of resources. This is applied for the whole industry but particularly in fields of mineral processing. The most important resources are energy and water. The shortage and price advance of energy is worldwide noticeable whereas the shortage of water is regionally limited at present. However due to the increasing world population, associated with a rising standard of living, water will become more and more important. Studies of the Unesco from 2001 indicate that the total water consumption raised seven times since the last 100 years at a growth of population of just three times. (UNESCO-Currier, 10/2001). This trend is going to be increased. While today more than 90 % of the humanity has access to clean water, in 2050 just about 50 % will be in the same situation. These figures indicate the importance of a gentle handling with the resource water. Further more the disposal of fine products, containing most of the water, is an environmental concern and in the future the mining and processing of raw materials will become important and necessary in desert, arid or permafrost areas. In these areas just efficient dry cleaning technologies will allow an economical beneficiation or better enable the processing at all. Most of the separation technologies with high throughput rates in mineral processing are based on wet processes. This applies especially for the separation of fines. Though there are some dry technologies available for the separation of coarse materials, like pneumatic gravity separation [air jigs and air tables], magnetic separation and not least sensor based sorters. Dry separation of fines is bounded mostly on cost intensive and low throughput technologies. The pneumatic separation undergoes at present a renaissance, mainly due to the development of the all air jig by the German supplier Allmineral. This newly developed sorting device yields good results in the separation of coarse to medium size material. All these facts and figures show the potential and motivation for developing an efficient dry separation device for fines. The following article delineates the development, performance and chance of a new dry separation technology for fines.

Jan 1, 2014

By I. L. Grigorova

As a result of the main processes of the limestone treatment ? sawing, buffing and polishing, a technological waste is usually obtained. These final tailings consist of a water suspension with highly variable solid phase content and granulometric composition. Since the waste is conducted to a tailing pool or another place, this leads to environment pollution. In this work the slurry waste generated during the limestone processing in a Bulgarian limestone manufacturing company was characterized. The chemical composition, particle size distribution, solid phase content, whiteness, yellowness, abrasion, specific surface and density were determined. The possibility of obtaining building/construction materials from limestone processing waste was studied in a laboratory scale. The technological tests included thickening, filtration and drying of waste products. Continuous operation laboratory thickener was used. Coagulant Accepta® 8302 (aluminum sulphate solution) and anionic flocculant Magnafloc® 155 were found to be the most effective in the sedimentation of the products. Filtration tests were performed using a laboratory pressure filter. Drying tests were carried out in laboratory facilities using the direct heating method. On the basis of the laboratory results a technology for limestone treatment waste was developed. A production line for building materials from limestone slurry was set up. As a result the manufacturing company has a possibility to use circulating water.

Jan 1, 2014

By I. Silin, H. Wotruba, J. Huben, A. Ognyanova

"With increasing shortage of raw materials, the beneficiation of ultra-fine ores will play a larger role in the near future. Many established process technologies do not yield satisfactory separation results for ultra-fine materials. Without selectivity, high-grade concentrates cannot be produced. The material at hand is a taconite which had to be ground to d(90) = 25 µm to guarantee liberation of the iron oxides. The comminution was done by High Pressure Grinding Roll (HPGR) and resulted in smooth surfaces and clear grain boundaries. This is an indication of selective grinding and mineral liberation. Further processing steps included selective desliming, magnetic separation as well as reverse flotation. INTRODUCTION During the last centuries, the processing of iron ores became increasingly important. The coarse-grained, so-called lump ores that are ready for direct usage in blast furnaces without further processing are becoming gradually less abundant. The processing of ultra-fine-grained ores, which in addition require a complex ore beneficiation due to the composition of the material, will progressively gain relevance with increasing resource shortages in the future (Arvidson, 2013). The term “ultra-fine” does not hold a precise definition in mineral processing. In this paper, “ultra-fine-grained” ores are defined by the required grind size for full liberation smaller than 20 µm. Many established mineral processing technologies do not yield satisfactory separation results for ultra-fine materials. Thus, they are limited in their application to produce high-grade concentrates suitable for sintering and pelletizing for direct reduction processes. The production of a high-grade iron concentrate (over 68% Fe) with low silica content (under 2.5% SiO2) is possible from both magnetite and hematite containing ore. In addition to the mineral processing technologies (magnetic and gravity separation, flotation), technologies for the liberation of fine-grained iron ores need to be developed and improved. In contrast to the conventional wet grinding circuit by means of tumbling mills, several future trends in dry and wet grinding and regrinding are already in use. These include technologies such as vibration mills (Palla®Mill), stirred media mills (Vertimill®), vertical roller mills (Loesche) and high-pressure grinding rolls (HPGR) (Jankovic, 2015). This study preliminary investigated the mineral processing of a low-grade, ultra-fine-grained, complex iron ore in a laboratory scale after dry grinding by HPGR to 90% < 25 µm without consideration of the grinding, milling, energy and classification cost."

Jan 1, 2018

By A. N. Lazaridi, S. I. Afanasenko, S. A. Safonov

"This scientific work presents the results of comparative tests of centrifugal concentrators with a vertical and horizontal axis of rotor spinning. The article also describes a qualitative analysis of the behavior of mineral particles in a centrifugal field with fluidization for concentrators with a horizontal axis. The analysis was aimed at studying the effect of the quantity of fluidization holes in the basket on the degree of magnetite recovery and the effect of the basket rotation speed. The experiment demonstrated that concentrators with a horizontal axis are not inferior in terms of the qualitative recovery indicators to concentrators with a vertical axis. The researches also provided facts about the wide practical application of concentrators with a horizontal rotor arrangement. INTRODUCTION Methods of gravity concentration, attractive for their ecological purity, see their revival. First of all, this is due to the invention of centrifugal concentrators with the fluidization of the layer of mineral particles. The creation of a new generation of gravitational centrifugal concentrators made it possible to achieve a tangible breakthrough toward the direction of reducing the grain size of mineral particles effectively divided by density, up to 10 µm at a high production capacity of the vessels reaching 500-600 tons per hour. Such separators enable dressing a crushed ore of flotation grade and in some cases replace the flotation process, especially in primary operations, in joint cycles. In the long term, this method of concentration should significantly expand the scope of application, replace partial flotation processing, ensure the introduction of environmentally friendly energy-saving technologies at ore-processing plants. Summarizing the international experience for the last 30 years, it can be confidently asserted that centrifugal methods of concentration have become widely used in processing schemes for the separation of finely dispersed products in the mining industry. An interest in the creation of installations using centrifugal acceleration for the separation of mineral particles by density has particularly grown. Dozens of centrifugal concentrator designs have been created and continue to be improved. Centrifugal concentrators have a number of obvious advantages, which are especially relevant today. Losses of fine gold during the process of mining are well known. Gold washers screw, spiral separators, jigging machines and sluices traditionally used in the production processes do not solve the problem of fine gold recovery. Table 1 shows the results of comparative tests of a centrifugal concentrator (ITOMAK) and other concentration equipment. According to the research conducted by the company GMRS, Krugersdorp, South Africa (2000), the initial material was gold ore crushed to 150 micrometers (90%)."

Jan 1, 2018

By A. Kamali Moaveni, A. Boehm

"The current research study addresses a physical separation process of basic oxygen furnace slag “BOF-Slag” (also called Linz-Donawitz “LD” slag) for the removal of phosphorous. In order to recycle the LD-Slag into the steelmaking process, the physical dephosphorization methods are considered. The systematic geometallurgical investigation carried out on particle classes of decreasing size, which were further subdivided into susceptibility classes, shows intimate intergrowth beyond 40 µm due to slag´s fast cooling rate. Generally, LD-slag is constituted of oxide and silicate phases, among which di-calcium silicate “C2S” dominates. About 0.5 mass% of phosphorous was detected in the LD- slag, which is exclusively situated in the lattice of the C2S. The comparatively high grinding resistance (Rittinger index 12.9 cm²/J) of the LD-slag reflects the energy demand to liberate the phosphorous carrying phase from the iron containing minerals, while separation efficiency decreases in the very fine particle size range. Hence, the conversion of the phase intergrowth pattern was considered alternatively to re-build the mineral phase structure of the material to a separable interlock pattern. Carbon dioxide, as the most convenient substance in the steelmaking plants, was applied to digest the C2S in the presence of water and to reduce the basicity of the slag slurry. As a result of C2S-CO2 chemical reaction, calcite and calcium silicate are precipitated at the surface of the oxide particles and carried between 25% and 75% of the total phosphorous, respectively. Accordingly, the mobility of the phosphorous content phase to the top of the grains serves the possibility to separate the precipitated layer by mechanical attrition process. This paper is focused on the impact of the intergrowth pattern alteration on the slag´s separability characteristics. Moreover, the operating conditions of the carbonization process, such as temperature and pressure, on the deconstruction kinetics of the C2S and the generated products will be considered. INTRODUCTION The steelmaking BOF-Slag is a stony aggregate waste from the steel manufacturing process. The investigated slag by the current research work was provided by voestalpine steelmaking plant in Linz, Austria. The current legislative situation in Austria restricts the historical application of slag as construction material, due to the high level of heavy metals content and corresponded land-filling and transportation costs of slag, therefore the demand for recycling of BOF-Slag to the steelmaking process has raised, as an alternative application. Statistically, voestalpine steelmaking plant produces about 130 kg BOF-Slag per ton of final steel product, which serves annual BOF-Slag production of 700,000 ton, approximately."

Jan 1, 2018

By Rodney J. Hundermark, Sharif Jahanshahi, Shouyi Sun

"The major platinum producers in South Africa make use of electric furnaces for the melting of PGM bearing nickel - copper concentrates. To gain better understanding of the furnace operation, research was conducted at CSIRO Minerals in Melbourne, Australia. One aspect of the research project was the investigation of the factors affecting the electrical conductivity of melter type slags.Electrical conduction in slags can occur through two mechanisms: ionic and electronic. There is good understanding of the ionic mechanism. In slags containing high levels of iron, the dominant mechanism is electronic. There is limited understanding of the electronic mechanism and one of the aims of the research was to investigate this mechanism further.Experimental work was carried out on Al2O3.CaO.FeOx.MgO.SiO2 slags similar in composition to the melter slags. Conductivity increased significantly with iron oxide content. Above 20wt% FeOx, electronic conduction was significant and the conductivity varied with the oxidation state of the slag. As the iron oxide content was increased further, the electronic mechanism became more dominant. The conductivity reached a maximum at around pO2 = 10-7 to 10-4 atm., although this value was dependent on the total iron oxide content and basicity of the slag."

Jan 1, 2003

By V. K. Gupta

Selection of mill size for reducing a feed material of a given size to the desired product size is generally based on the specific energy estimate obtained from Bond test. Over the last thirty years or so, an attempt has been made to develop a more accurate and powerful alternative approach based on the characterization of the particle breakage kinetics and material transport through the mill over a range of operating conditions of interest and correlating the degree of size reduction achieved with the net specific energy input to the mill. Particle breakage kinetics are described in terms of the specific grinding rate and breakage distribution parameters for the individual size fractions. Precise estimates of these parameters and the net energy input to the test ball mill (a laboratory or pilot scale mill) are important for development of desired energy-size correlations. In this context, three tasks are important: (a) preparation of the feed charge, (b) design of batch grinding experiments and (c) computational technique used for estimation of the breakage rate and breakage distribution parameters. This paper highlights several aspects of these three tasks that have been overlooked by researchers working in this field, and describes a more appropriate approach for estimation of model parameters and specific energy input. Several examples are included based on the data available in the literature and those generated in our laboratories to illustrate important points.

Sep 1, 2012

By J. K. Qu

As one of the key inorganic chemical industries, the chromate chemical industry has spawned extensively public concerns due to the resulted environmental pollution. The cleaner production technology for chromium compounds bases on sub-molten salt medium developed by the Institute of Process Engineering, Chinese Academy of Sciences has greatly decreased the reaction temperature and energy consumption, significantly in-creased the utilization ratio of the chromium element, and successfully achieved the comprehensive utilization of chromite resources and zero emission of chromium-containing residue. The separation process of production is the most important components in the cleaner technology. In this work, we studied two parts: the first is the removal of SiO2, Al3+ from the system and the recycling utilization of alkali metal medium through adding Ca(OH)2 and CaO; the second is to get more pure K2CrO4 crystalloid and remove K2CO3 from KOH solution through evaporation to prepare raw material for manufacturing Cr2O3 and get 50%(wt) KOH. The results obtained show that Ca(OH)2 can remove Al3+ more than CaO and has lower caustic ratio than CaO when they were added 110% of theoretic quantity. The optimal pure K2CrO4(96%) can be gained at 45 Celsius degree in 30% KOH solution and K2CO3 in 50% KOH solution could be decreased to 3.5%(wt) at 40 Celsius degree. And then K2CO3 can be causticized with adding Ca(OH)2 to recycle potassium alkali. The impure material can be re-moved and suitable raw material for manufacturing Cr2O3 can be gotten and reaction medium can be also recycled in this process technology, realizing cleaner production effectively.

Jan 1, 2014

By S. Owada

A national project of ?Establishing ?Green-Hydrogen (G-H)? Society in Honjo-Waseda Area? is now being developed by Waseda University together with four other universities and ten companies. The project involves three tasks of technological development of, (1)?G-H? production, (2)?G-H? refining, transportation and storage, and (3)?G-H? utilization. This paper focuses the first task of ?G-H? production from aluminium dross. We developed the physical treatment process by combining selective grinding with vibrating rod mill and electrostatic separation, in order to produce two kinds of materials, one is metal aluminium concentrate to recover it and the other is raw material to produce ?G-H? and aluminium hydroxide which can be generated by the treatment with sodium hydroxide aqueous solution. Here, we described the concentration mechanism of metal aluminium in the selective grinding and electrostatic separation and proposed a separation flowchart for optimizing the ?G-H? system in Honjo-Waseda area.

Jan 1, 2014

By G. Pahomova

"It developed an alternative to traditional flotation enrichment refractory of complex lead-zinc ores to obtain conditional lead and zinc products. The scheme involves the use of the processing method of gravitational enrichment of the primary cycle and the combined gravity-flotation-hydrometallurgical in finishing. The method has a high level of comprehensive utilization of mineral raw materials in relation to the elements that are extracted in the process of enrichment in lead concentrate, and the increase in recoverable value of processed ores. INTRODUCTION The primary source of lead are complex sulphide lead-zinc ore, lead ore actually rarer. The value of lead and zinc ores (except lead and zinc) is determined by the presence in them of a wide range of associated components: silver, contained mainly in galena; gold; bismuth in the form of its own minerals, but is associated with galena; cadmium contained mainly in the sphalerite; indium, thallium and gallium contained in sphalerite and galena; selenium and tellurium are present as impurities in the sulfide, tellurium is also found in the form of its own minerals. Of note harmful impurities antimony, which is often associated with lead sulphosalts and arsenic, having a substantially own minerals. By quality (content of lead, or the total content of lead and zinc) lead-zinc ores are divided into rich, ordinary and poor; by oxidation - to sulfide (with a lead oxides content less than 15% and zinc oxide content less than 10%), mixed and oxidized (50% oxide); the latter have a subordinate importance as a source of zinc and lead. Traditionally, the most contrasting technological properties of sulfide ores of nonferrous metals considered flotation properties, which determines the priority in the selection of flotation technology of their enrichment. Other methods of enrichment - gravity (jigging and enrichment in heavy suspensions), radiometric sorting (separation) are used as preliminary operations whose main purpose is to increase the content of lead and zinc in the ore sent to flotation, as well as the removing of part of empty rock in dumping tails prior to flotation. Effective implementation of these methods is possible at large size emphasizing in the ore of lead and zinc minerals, which is typical of the rich ores and which so far mainly worked. At the same time, non-ferrous metal ores (polymetallic, lead-zinc, copper-zinc, etc.) have a sufficiently high contrast to gravitational properties since ore minerals have a higher density compared with a rock minerals. But the gravity of the practice of non-ferrous ores enrichment is not widely used, despite its high degree of environmental safety and lower cost expensive."

Jan 1, 2018

By M. Pischtschan, S. Belz, M. Perrucci

In High Pressure Grinding Rolls (HPGR), the material grinding takes place between the fixed and floating rollers. In this regard, the rollers start to wear over a period of time, which is impacted by for e.g.: ore characteristics, operating pressure, feed material size and non-uniform feed presentation across the roller width. HPGR operational experiences have shown that the rollers do not wear at the same rate. This differential wear rate over time leads to differences in the tangential speeds of the rollers, causing an uneven gap between the fixed and floating rollers in relation to the material. This unwanted but extremely common situation results in a less effective grinding process due to the fact that the slip between rollers is not optimal. As the rollers wear profile increases, the roller with smaller diameter starts to wear further, deteriorating the comminution efficiency up to a point where operators have to stop the HPGR to replace the rollers. Since the wear rate of the rollers is not equal, the replacement of the same cannot be properly planned so that their life-time are fully utilized. In this paper, a dynamic load share control with the use of ABB’s variable speed drive system is proposed, which provides the possibility to the HPGR operator to impact the roller wear in such a way that it equalizes the wear rate to a certain extent and extends the roller life time. Called RollXtend™, this solution includes a load share factor which can be parameterized based on the wear measurement performed manually during maintenance procedure. Additionally, this paper describes an automated load sharing concept based on a non-invasive wear measurement method. The partial results of the technology trial in a copper/gold mine are presented, which aimed at detecting stud damage and estimating the real rollers profile throughout their life time. The final objective of the pilot project was reduce the amount of planned and unplanned downtimes of the HPGR by increasing the rollers life time and avoiding catastrophic stud damages.

Jan 1, 2018

Goethite ore are the third most abundant source of iron. The overwhelming part of these ore is represented by low-grade varieties which cannot be used in iron and steel industry without preliminary beneficiation. Biomass is a renewable solid fuel, which is feasible for the substitution of coke and coal in the manufacturing due to its lower contents of harmful elements and abundant raw material sources. Utilization of biomass in iron ore sintering process as heating agent and reducing agent contributes to energy conservation and emission reduction. The biomass was mixed together with goethite ore for roasting process to investigate the effects of reduction roasting. The results show that the goethite ore is dramatically reduced and magnetized into maghemite by biomass with the biomass dosage less than 20% and the roasting temperature below 650 oC. When the goethite ore roasted with biomass, the magnetization values could be enhanced more than two orders of magnitude, meets the standard of magnetic separation, which could significantly reduce the iron beneficiation cost. Keywords: biomass, goethite, reduction, magnetization, roasting

Sep 1, 2012

As a leading global company in the mining sector, we are committed to sustainable development. To this end, we invest in the responsible, integrated management of economic, environmental and social issues. Vale?s objective is for our businesses to produce local, regional and global prosperity, enabling the construction of a positive legacy throughout the lifecycle of our activities. This covers everything from talking with stakeholders and preventing failures to complying with legislation, paying constant attention to environmental issues and respecting ethics in business. Keywords: sustainable development

Sep 1, 2012

By S. K. Chaurasiya

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

Sep 1, 2012

By Xumeng Chen, Yongjun Peng, Dee Bradshaw

Regrinding rougher flotation concentrates has become a common practice when processing low grade and complex ores. It not only reduces the particle size and improves mineral liberation but also modifies particle surfaces and pulp chemistry due to the strong electrochemical reactions taking place during regrinding. Therefore, the floatability of minerals in the subsequent cleaner flotation is influenced by the regrinding conditions. This paper presents the effect of regrinding conditions on the mineral floatability from both industrial studies in the plant and fundamental studies in the laboratory. Different regrinding conditions were considered, including grinding media, the electrochemical properties of minerals, pulp chemistry (pH, Eh, DO), and breakage mechanisms in tumbling and stirred mills. Results indicate that the selection of regrinding conditions and mill types should not only depend on grinding energy efficiency and liberation but also depend on the surface properties and pulp chemistry produced for effective mineral flotation and separation at the cleaner stage.

Jan 1, 2014

By M. Saghaeian, R. Hejazi, H. Abedini, M. Zare

Water recovery in mineral processing plants is one of the most important subjects because water supply is a critical matter economically and environmentally, especially in desert areas. In this paper, the filtration behaviour of two iron ore tailing sample has been investigated using laboratory scale vacuum and pressure filtration units. These samples including tailing from Sirjan and Zarand concentrate production plants with the d80 of 94 and 41 micron, respectively. The results show that by using vacuum filtration the cake moisture content of Sirjan sample would be about 24%. But the filtration time is too long and vacuum belt filter cannot be used in industrial scale. Adding about 40 g/ton of flocculant would decrease the filtration time by about 30% and make the vacuum belt filter appropriate for dewatering of this sample. For Zarand tailing sample, the vacuum filtration would produce a wet cake by about 31% moisture content. Filtration time is too long and adding flocculant would not improve the results very much. So pressure filtration must be used for dewatering of this sample. The results of laboratory tests show that using pressure filter would reduce the cake moisture content to 21%. The filtration time is logical, so this process can be used for Zarand tailing dewatering.

Jan 1, 2014