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By Elves Matiolo

This paper describes, in detail, results obtained from a research study of a complex iron ore aiming to produce a pellet feed concentrate with at least 65% of Fe and less than 3.5% of SiO2 in the final concentrate. The work includes an ore desliming followed by column flotation at laboratory scale. The ore sample was from Carajás province - Brazil and represents a complex low grade compact itabirite ore, analyzing 35.9% Fe, 45.1% SiO2 and 0.57% of Al2O3. Yet, the feed was treated previously by magnetic separation and grounded to 97% < 20 µm; this sample was named MAG 2. The chemical and mineralogical characterization of the MAG 2 sample showed that Fe and SiO2 grades were 50.7% and 24.3% respectively and was composed mainly by hematite, goethite and quartz. The particle size distribution, using a laser diffraction technique, showed that 90% of the particles were < 18 µm; 50% less than 8 µm and 10% minor than 1 µm. When the cationic reverse flotation without desliming was tested the selectivity of the process was very low and did not meet the concentrate metallurgical goals of the pellet feed product. However, when desliming was applied prior to flotation, a concentrate product with chemical characteristics of the pellet feed was obtained. The best results after desliming and column flotation achieved global iron metallurgical recovery of 72% with Fe grade in the concentrate of 66.5% and 2.1% SiO2 using starch as depressant for the iron oxides minerals at 1200 g/t ? 1500 g/t and an amine as the quartz collector at 100 g/t concentration (pH constant, at 10.5). It is believed that the desliming stage was key in the separation of the iron bearing particles and has a high potential for the flotation process of this type of ores.

Sep 1, 2012

By V. F. Petrov, O. D. Khmelnitskaya, V. M. Lodeischikov

"The processing of copper gold ores is one of the major issues of gold-mining industry in the beginning of 21st century. In this case, application of ammoniacal cyanidation process for this type of mineral raw materials deserves special attention. Irgiredmet Institute has carried out a wide range of studies on ammoniacal cyanidation process and evaluated the possible commercial use of this process for Russian operating plants. Copper gold-bearing ore from a current Russian deposit was studied. The content of gold and copper in the ore is 9.4 g/t and 0.4%, respectively. Based on the results of preliminary test work, a flow sheet was developed. It included gravity concentration followed by cyanidation of the gravity tailings using CIP. The flow sheet provides sufficient total gold recovery (91.5%). However, this technology has disadvantages, such as high specific consumption of reagents: 4.5 kg/t NaCN and 13.5 kg/t Ca(OCl)2 the ore and the increased gold grade in the liquid phase of the tails slurry (0.2 g/t). In order to improve cyanidation process parameters, test work on gravity tails processing using ammoniacal cyanidation was carried out. After the test work was completed, ammoniacal cyanidation flow sheet for copper gold-bearing ores was developed. Leaching conditions were optimized using recycled process solutions. Recommendations on gold recovery from the solutions and tails detoxification are given. The proposed flow sheet provides 91.5% gold recovery. In this case, compared to the conventional option, the consumption of cyanide decreases by 3-4 times.INTRODUCTION The technology of precious metals recovery from gold-bearing ores is based on cyanidation. This accounts for up to 90% gold recovery and the significant portion of silver (Lodeischikov, 1999). However, there exists the category of so called refractory ores. They are not amenable to direct cyanidation (without using additional expensive processes), or they are characterized by low indices of metals recovery and high consumption of reagents. The latter also include copper gold ores. Their deposits can be found extensively both worldwide and in Russian Federation. A feature of these ores is that they contain not only gold but also copper. It is considered not only as a valuable component but also as a harmful mineral impurity that hinders gold cyanidation, gold precipitation from the solutions by cementation onto zinc dust and adsorption onto activated carbon (CIL, CIP-processes), detoxification of cyanide bearing effluents."

Jan 1, 2018

By A. Kuriwada

Dolomite is a mineral, which consists of CaCO3 and MgCO3. In this work, a series of experiments were carried out in order to adsorb boron from a boron-containing solution using a calcinated dolomite sample, and then to desorb it from the loaded adsorbent. A particular modification on the surface of dolomite was observed when it was thermally treated at certain temperature, ranging from 750 oC to 1050 oC; in turn, it is the specific surface was increased. In other words, the experimental results suggested that the calcinated dolomite exhibited a high adsorption capacity for boron, indicating its effectiveness in effectively adsorbing boron from drinking water or wastewater.

Sep 1, 2012

By A. Erdem

In this study, approximately 3 tons of coal sample taken from thickener entrance was prepared by mineral processing techniques and cleaned by gravity methods. The samples were classified to 5 size fractions by wet screening. The size fractions of +1mm and -1 +0.500 mm were chosen for direct consumption or cleaning by spirals. The studies by Multi Gravity Separator (MGS) were carried out with the -0.500 +0.280 mm and -0.280 +0.020 mm size fractions where the -0.020 mm fraction does not used in the experiments. The clean coal fractions of +1 mm and -1 +0.500 mm obtained by classification were subjected to lower calorific value (LCV), ash and total sulphur analyses. The results were 4168-4946 kcal/kg (on dry basis), 31.01-38.54 % ash and 4-4.27 % total sulphur content respectively. The results of the clean coal concentrated by MGS experiments in -0.500 +0.280 mm fraction was found 5918 kcal/kg LCV, 19.82 % ash content and 80.47 % combustible recovery. The results for the -0.280 +0.020mm fraction were 6004 kcal/kg LCV, 19.19 % ash content, 80.47 % combustible recovery respectively. With reference to the above experimental results, pre-economic evaluation studies were completed and decided to construct an additional unit to the plant. Capacity of the constructed unit is 75.000 t/y which corresponds $ 2.600.000 income in a year. General Directorate of Turkish Coal Enterprises concluded to apply this project to the other coal washing plants in the country due to the successful results of this study and laboratory studies has been going on by MTA currently. Keywords: coal tailings, mgs, recovery, washery, pre-economic evaluation

Sep 1, 2012

By B. Q. Xiao

The nitrate content is an important factor for environmental water samples and flour. In a 0.35 mol/L H2SO4-2NO solution, has a strong catalyzing function on the decolourization of Gallocya-nine (GC) oxidated by NaBrO3. Based on this, a novel method was developed to measure the NO and -3NO concentrations in water and flour. The flow injection technology was introduced into the analysis system. A single-valve dual- cingulums to inject which the Copperized-Cadmium slice and the reduction zone are isolated. The optimum solution for this method contains 1.48×10-4 mol/L GC, 0.06 mol /L NaBrO3 and 0.2 mol /L of NH4-2NOCl. Two empirical equations were proposed to calculate the and -3NO concentrations based on the measured signals. It can be used to measure -2NO of from 0.001 mg / L to 2.0 mg/L and -3NO of from 0.002 mg / L to 2.5 mg/L. The measurement frequency can be up to 20 samples / h. The relative standard deviation for eleven samples is less than 5%.

Jan 1, 2014

By M. D. Kaizer

PETROBRAS started its Oil Shale process development in 1953, the PETROSIX process which was developed and tailored to Irati Oil Shale formation. Since 1991, the industrial plant called MI (Industrial Module) has been operating, producing more than 20 million barrels of oil. In order to continue the oil shale exploration, a new shale mine is been opening. This article reports the planed measures taking in order to limit the environmental impacts and to return the land as close as possible to the original condition, as well as with the disposition of the process waste and the city garbage. It shows that the remediation process starts during the mining activities and continues after the mine exploration. Another characteristic of the Petrosix process, the pyrolysis of tires will be focused.

Jan 1, 2014

By Katja Ohenoja

Polymer dispersants, also known as grinding aids, are widely used to reduce the viscosity of mineral particle suspensions and to improve energy efficiency during fine grinding. In this study, the effect of polymer dispersant with different molecular structure on the suspension properties in the wet stirred media milling of limestone was studied. The stability of suspension was studied by combining rheological and zeta potential measurements. The PDI value of polymers corresponds to the width of the molecular weight distribution so that low PDI corresponds to narrow MW distribution and high PDI to the wide one. In this study, two traditionally fractionated polymer dispersants with high PDI (over 2) and one novel polymer dispersant with low PDI (1.2) has been tested. It was noticed that dispersants worked as electrosteric stabilizators and prevented the agglomeration of ground limestone particles. The uses of dispersants could increase solids concentration used in the grinding experiments and at the same time lower the particle size and specific energy consumption. The obtained particle sizes were about 1 µm regardless of which dispersant was used or the amount of it. The novel dispersant with low PDI reduced viscosity most when compared with the traditionally fractionated polymer dispersants. Results indicated that even higher solids concentrations can be used at the same amount of dispersant when the novel low PDI polymer dispersant is used. Alternatively, lower dosage of novel low PDI dispersant can be used compared to traditionally fractionated dispersants.

Sep 1, 2012

By L. S. Zhou

Germany-made AFX-100 multi-grade fluidized classifier, with exquisite built-in structure and unique novel design, materializes not only advanced and efficient classification, but also precise particle distribution and safe operation, in addition to lower energy consumption and operational cost. It, simultaneously in place of screw grader, water cyclone, and fine mesh sieve, is equipped with multi-function, and indicates superior advantage in comparison with other else grading facilities. As the third-generation equipment, which is efficient and modern, it, in China and therefore all over the world, will find wide application in processing both fine and ultra-fine iron ore resources. Industrial test, carried out in Benxi Steel?s Waitoushan Iron Mine, shows efficient classification, i.e., ?74µm particle contents in coarse, medium and fine products come to 6.09%,11.82% and 82.73%, respectively, while qualitative and quantitative efficiencies end up by 74.38% and 87.66%, respectively. Its separation efficiencies amount to 2.2 times as many as spiral classifiers, 1.8 times as hydrocyclones, and 1.3 times as vibration high-frequency fine screens. Another industrial test, which was practiced in Anshan Steel?s Donganshan Sinter Plant, indicates that classification qualitative efficiency comes to 65.06%, equal to 1.51 times as many as hydrocyclones; yield, 55.79%; -71µm particle contents in medium and coarse products, 42.02%; -71µm content in fine product, 95.42%; and concentration, 12.33%. Estimated separation indexes are as follows: Yield for concentrate at 31.22%, up 0.22% than that from general processing line; concentrate grade at 66.42%, up 1.13%; recovery ratio comes to 65.84%, up 1.28%, which, based on pilot study, results in 20 million yuan of economic return for Donganshan Floatation Plant.

Jan 1, 2014

By T. Bhambhani, O. Yavuzkan, D. R. Nagaraj

"The recovery of oxide Cu minerals by flotation is a longstanding challenge in the minerals industry, especially for high acid-consuming ores which would not be economical for direct acid leaching. Sulfidization (often using controlled potential sulfidization or CPS) using NaSH (or Na2S) followed by flotation using traditional sulfide collectors is the widely used technique. CPS has certain limitations: a) inability to recover certain oxide Cu minerals because they are refractory to sulfidization, b) high consumption of NaSH (or Na2S), and c) potential health and safety hazards associated with NaSH (and Na2S). Flotation of oxide copper minerals using alkyl hydroxamate (AHX) collector has been studied extensively. Investigations using single minerals and laboratory ore flotation have been conducted in the past to demonstrate the efficacy of alkyl hydroxamates. The technology has been used intermittently in plants. One of the main challenges in plant use has been quantifying the true potential for alkyl hydroxamates for recovery of various oxide Cu species in complex and variable ore systems and identifying the most suitable conditions for optimal use. Quantitative mineralogical analysis using QEMSCAN was used in this study to characterize flotation products lab flotation samples. Analysis of concentrates and tails from hydroxamate flotation and CPS flotation stages demonstrated that certain oxide Cu minerals respond exclusively to alkyl hydroxamates and not to CPS. The hierarchy of interaction of AHX with the various oxide Cu minerals could be inferred from these studies. Finally, these studies also allowed quantification of a group of minerals species, which (erroneously) report as part of the Acid-Soluble Cu [ASCu] but cannot be recovered by flotation, thereby facilitating an estimation of the true recovery potential for alkyl hydroxamate.INTRODUCTIONCopper that is economically recoverable occurs in three major types of ores, which are defined by the modal mineralogy of Cu. For sulfide ores, Cu occurs as sulfide minerals and is satisfactorily recovered by flotation using sulfide collectors. Non-sulfide ores, which contain Cu in the form of oxides, phosphates, carbonates and silicates, described in the industry as “oxide” ores (or ores containing “acid-soluble” Cu or ASCu), are currently treated using hydrometallurgy, which involves leaching with dilute sulfuric acid followed by solvent extraction and electrowinning, unless the ores contain acid consuming gangue minerals such as dolomite. For mixed sulfide-oxide ores (i.e. containing both sulfide and oxide Cu minerals) that do not contain acid consuming gangue minerals, Cu values are easily recovered by flotation of sulfide Cu minerals followed by leaching of oxides (only when a leach plant is available). However, when the ore contains acid consuming gangue minerals flotation is required to recover both sulfide and oxide Cu minerals."

Jan 1, 2018

By C. A. Acuña

Extensive literature exists on the motion of single bubbles and the behaviour of swarms of bubbles. This contribution describes work to track and reveal the motion of individual bubbles in a swarm. The technique is based on high speed cinematography and tracking of multiple moving objects. Image processing algorithms were implemented in Matlab to isolate and measure geometric proper-ties of the bubbles in image sequences recorded at 2 ms interval; and these properties were compiled into a data structure. To track a bubble, the geometric properties and a matching criterion were applied on consecutive pictures to identify the bubble. The bubble trajectory was reconstructed from the data structure for the matched objects. The methodology is briefly described. The new technique was tested for bubbles produced at slot-type spargers (i.e., approximately 2-D swarms) in the presence of two frother types (&apos;strong&apos; and &apos;weak&apos;). Two observations are discussed: a) that bubble motion in a swarm describes a velocity-size relationship dictated by the dominant bubble size class; and b) that surfactant type influences bubble rise velocity for bubbles in the range 0.1 mm to 4 mm. The latter suggests surface viscosity rather than surface immobilization determines bubble rise velocity.

Jan 1, 2014

With rapid development of Chinese iron & steel industry, it is of significance to intensify the utilization of domestic complex iron ore resources. The tin, zinc-bearing complex iron ores are typical polymetallic and intractable ones because of the complicated intergrowth relations among the multi-elements, and they have not been efficiently utilized, presently. Based on the thermodynamic analysis of iron, tin and zinc oxides reduction by CO, the technological conditions of tin and zinc recovery and pellets preparation from tin, zinc-containing iron concentrates by selective reduction roasting are studied and a new comprehensive utilization process is developed in this investigation. Under the optimum conditions, the tin and zinc volatilization is respectively in excess of 80% and 70%, and the compression strength of roasted pellet is more than 2500 N/P. Moreover, the residual tin and zinc in the finished pellets is below 0.06%. The finished pellets can be used as high quality iron-making burdens for large-scale blast furnace.

Jan 1, 2014

By Evvie Chockalingam

Acid mine drainage (AMD) is a perennial problem particularly in abandoned mines, occurring due to the oxidation of sulphidic mine wastes. AMD is usually characterized by high concentration of dissolved metal ions, sulphate and low pH. The efficacies of substrates such as rice husk and the bark of Eucalyptus tereticornis (Sm.) are assessed for the removal of metal ions such as iron, zinc and copper from acid mine water obtained from an abandoned copper mine. Over 99 % of Fe, 98 % of Zn and 95 % of Cu removal could be achieved from acid mine water, with a concomitant increase in the pH value by three units using rice husk as an adsorbent. With respect to tree bark as an adsor-bent, about 96 % of Fe, 75 % of Zn and 92 % of Cu could be removed from the acid mine water with an attendant increase in the pH value by two units. The free energy of adsorption of the metal ions onto rice husk and tree bark is found to be negative in both the cases, while the adsorption process is endothermic in the case of rice husk and exothermic for tree bark. The adsorption process is found to adhere to the Lagergren pseudo-first order rate equation. The reduction of sulphate con-centration in the acid mine water is achieved using a typical sulphate reducing bacteria namely De-sulfotomaculum nigrificans. Desorption experiments indicate that about 88 % of Zn, 87% of Cu and over 77 % of Fe could be recovered from rice husk and over 70 % of Fe, 82 % of Zn and 77 % of Cu could be desorbed from the metal loaded tree bark using 5 M HCl. The possible mechanisms of metal ion and sulphate removal from acid mine water using rice husk and tree bark are discussed.

Jan 1, 2014

By J. A. Sweet

The issues facing graduate training in the mineral processing industry are not too different today from those that prompted the initiation of the Anglo American Platinum Graduate Development Programme (AGDP) in 2002. Graduate metallurgists in South Africa enter the industry from different undergraduate programmes at various tertiary institutions, and so the knowledge and skills of the young graduates varies. Further, the geographical expansion of the industry combined with the downsizing of business units means that there are fewer opportunities for young graduates to be mentored through their first few years on site. Anglo American Platinum chose to address these issues by implementing an intensive, structured graduate training programme for all their new metallurgical graduates, known as the AGDP. The first two years of experience of the AGDP, from the viewpoints of both graduates and lecturers, were presented to the mineral processing community at the IMPC in Turkey in 2006 (Sweet et al, 2006). From the beginning, the programme was structured in a modular fashion to include a basic technical ?toolbox? including statistics, the scientific method and sampling protocols, while the mineral processing content comprised advanced learning in comminution, classification and flotation (later extended to include hydrometallurgy). Technical communication ? both written and verbal ? was included from the start. The programme was focussed very strongly on site work (?learning by doing?), with a major integrated site campaign conducted and analysed by each cohort. In 2012 the AGDP will accept its ninth cohort into the programme. This paper describes how Anglo American Platinum and the University of Cape Town have developed and adapted the programme over the last few years, in response to the challenges of the global recession, skills retention, and the changing operational needs of the company. The programme, which was drawn up to accommodate around 15 concentrator-only graduates, now accommodates 35-40 concentrator, smelter and refinery graduates annually. The programme has also been modified to facilitate new graduates spending most of their first year on the operations. The benefits of the programme for Anglo American Platinum have been tangible, and will be discussed in the paper. Keywords: graduate training, technology transfer

Sep 1, 2012

By Swati Mohanty

Spiral concentrator, which works on the principle of gravity separation, is widely used in the mineral industries for separation of solid particles based on the size and density. In the present study, CFD simulation of the flow profile on a laboratory scale spiral concentrator of height 2.29 m, pitch 0.435 m and width 0.17m was carried out. A single computational domain covering the entire spiral was considered. Volume-of-Fluid algorithm was used to track the interface and predict the flow profile. In the present study the Donor-Acceptor method was used for the calculation of volume fraction in the cell. Simulation results show that the velocity increases as the water flows down due to the convective force and gravitational force, but the viscous force acting in the opposite direction retards the flow. Thus the maximum velocity is attained at turn three at which the viscous force overpowers the other forces and further down the velocity decreases. Measured water depths along the radius of the spiral at various heights were compared with simulated depths, which were in good agreement. The simulated liquid phase velocity profile was used to carry out preliminary studies on the flow profile of solid particles of size 500 micron and densities 2600kg/m3 and 5100kg/m3, based on the Lagrangian model taking into consideration fluid-particle interaction.

Sep 1, 2012

By S. Chuanyao

In last decade, along with its booming Chinese economy, China?s higher education has experienced rapid growth. In 2010, the number of various colleges totals more than 3500, with 2.2 million faculties registered. Currently there are almost 30 million students studying in the colleges, 3 times more than 10 years ago. Mineral Processing was initiated in 1949 as a sub-discipline of Mining Engineering, one of the 13 first level disciplines. Mineral Processing is now established in 34 Chinese colleges, recruiting 2600 undergraduate students, 540 postgraduate students and 100 PhD students every year. A further 9 institutes offer postgraduate education in this field. More than 3000 graduates majoring in Mineral Processing join the industry or institutions each year. The four-year undergraduate teaching and practical training in the colleges is designed to produce qualified mineral processing professionals. This includes courses in mathematics and natural science, fundamental engineering and basic and specialization courses. Recently, the ?Excellent Engineer Program? was launched to strengthen students? practical capabilities. This is a 3+1 teaching and training model; 3 years of theoretical course study plus 1 accumulated year of various practical studies, either inside or outside the college. As for graduate employment, mining-related major graduates have been in a good demand thanks to the intensive investment in mineral sector by Chinese companies. The shortage of experienced metallurgists generates a greater than 90% employment rate for Mineral Processing graduates. However, the biggest problem we are still facing is the gap between the quality of the graduates and the requirements of industry, as a result of occupation attraction, teaching systems, faculty quality, and so forth. Another problem is international orientation. Although nowadays Chinese-foreign cooperation in college education is popular, collaborative mineral related projects are far less common, leaving much room for improvement. Looking ahead to the next 10 years, we still have the right reasons to estimate continued prosperity in the minerals sector as well as mineral processing education in China. A brief analysis and views on this will also be shared in the presentation. Keywords: China, mining engineering curriculum, excellent engineer program

Sep 1, 2012

By F. Göktepe

Flotation gases and conditioning of the pulp with them are one of the important parameters of flotation and should be taken into account especially in the flotation of sulphide ores. In this study, flotation of pure chalcopyrite and pyrite samples were investigated with air, oxygen and nitrogen as flotation gas and the effect of conditioning with these three gases also were performed. Flotation gas was introduced for 5min, 10min, 15min and 20 min. For chalcopyrite flotation there was no drastic change in recovery when air, oxygen and nitrogen were used as flotation gas but conditioning the pulp with oxygen for 10 minutes increased the recovery about 8% where pulp potential has been approximately 25 mV with chalcopyrite and 150 mV with platinum electrodes. Conditioning with all three gases decreased the pyrite recovery by about 20% with 20 minutes conditioning. Pulp potential decreased in the presence of nitrogen while conditioning with air and oxygen increased the pulp potential for both electrodes. Generally potential increased for both minerals with oxygenation and aeration time but it was stable or slightly decreased with nitrogenation. Comparison of the gases showed that the different flotation gases do not effect flotation recovery but conditioning the pulp with these gases at pre-flotation effects chalcopyrite and pyrite flotation recovery, most dramatically pyrite.

Jan 1, 2014

By Haghi. Hamed, Javad Vazifeh Mehrabani, Mehdi Sedigh

In this investigation, the possibility of physical separation methods such as attrition scrubbing, hydro-cycloning and also reverse flotation were investigated for silica and calcite removal from relatively low grade kaolin. The head sample was provided by the Iran China Clay Company and the major oxides contained in the head sample were Al2O3, SiO2, CaO and Fe2O3 with grades of 15.07%, 71.05%, 4.35% and 0.52% respectively. The liberation degree of calcite and iron impurities from kaolin particles were over 80% for particles finer than 210µm and 53µm respectively. Attrition scrubbing tests were carried out with scrubber cell of the conventional Denver flotation cell model D-12. Laboratory scale hydro cyclone was applied for the beneficiation of kaolin. Attrition scrubbing tests with control screen of 106µm did not achieve the desirable yield for purification of this kaolin sample, but hydro cyclone experiments resulted in better results. Hydro cyclone with 2.54 cm diameter used and the only variable was the cyclone inlet pressure ranging from 68.65kPa to 98.07kPa. The best inlet pressure was found to be 68.65kPa. Based on the optimized condition, Al2O3 and CaO amount in the hydro-cyclone overflow was 23% and 1.47% respectively. However weight recovery of the overflow in each cyclone experiment was less than 30% and multi stages of hydro-cyclones would have to be applied for higher weight recovery and better yield. All of the flotation tests were carried out in the conventional Denver flotation cell model D-12. Reverse floatation tests for calcite removal were carried out under alkali pH based on full factorial design of variables in 2 levels including one center point. The three parameters tested were collector dosage (gr/ton), pH and depressant dosage (gr/ton). The collected data from flotation tests were analyzed and optimized collector and depressant dosage were 1000 gr/ton and optimized pH was 8.5. Under the above mentioned conditions, calcite removal was about 75% and CaO content in the final product was reduced from 4.35% to 1.33%. However calcite removal will increase to more than 83% if the feed particle size in flotation tests is reduced from 210µm to finer than 53µm. Finally after optimization, the best working condition and possible flow sheet were developed.

Jan 1, 2014

By G. Bonifazi

Mining activities belong to human history, they are lost in the mists of time. They usually impact on large portions of the territory, both directly (exploitation areas and logistic activities directly related to exploitation) and indirectly (exploited material handling, processing and storage areas). As a result, at the end of mine life cycle, dismissed areas usually cannot be directly re-utilized without efficient and well addressed rehabilitation actions. Main goal of the proposed approach was to analyze the results obtained when a set of procedures, based on the collection and the analysis of remote sensed data, is developed to evaluate the effect of rehabilitation of land contaminated by extractive industry activities and to perform a monitoring and registration of the environmental impact of such operations by the application and the integration of modern information technologies, as Earth Observation (EO) and Geographic Information Systems (GIS). The study was developed in the framework of the EU-Asia program of the European union (EXTRACT-IT Project-Contract No: CN/ASIA IT&C/006 (89870): Application of Information Technologies for the sustainable management of Extractive industry activities) and it was addressed to three different dismissed mine areas in India, Thailand and China, respectively. The results, in terms of methodologies selected, strategies applied and results obtained, are described with particular reference to Fuxin coal mine area in China.

Jan 1, 2014

By Y. S. Sun, P. Gao

Compared with conventional roasting and magnetic separation processes, higher reduction temperatures and stronger reducing atmospheres are used in reduction technologies to reduce iron oxides to metallic iron, which is often liberated during reduction and amenable to magnetic separation. Reduction and magnetic separation of an Australian refractory iron ore was therefore studied as a function of reduction temperature, time, coal addition, feed thickness and size of Australia iron ore. It was found that during reduction, the particle size of the reduced iron increased with reduction temperature and time. Subsequent magnetic separation tests were further conducted on the reduction products. A reduced iron powder with a Fe grade of 85.67% was obtained at a Fe recovery of 87.82% under optimum reduction conditions where a metallization rate of 85.82% was achieved. The mechanism involved in reduction is discussed based on XRD and SEM examinations. And the results indicated that theiron minerals such as hematite and limonite in the Australian iron ore were reduced as follows: Fe2O3?Fe3O4?FeO?Fe. Furthermore, the metallic iron particles produced by reduction increased in size with longer reduction times.

Jan 1, 2014

By C. P. Lowes

"The REFLUX™ Classifier (RC™) consists of a fluidized bed housing, with a system of parallel inclined channels above. This system performs a simultaneous gravity separation and desliming of the feed material, utilising the inclined channels in order to retain the relatively fine dense particles. These particles promote the formation of an autogenous dense medium within the fluidized bed. Relatively large, low density particles are displaced from the fluidized bed and conveyed upwards through the inclined channels reporting to the overflow with other finer particles. Given the hydrodynamic role of both the particle size and density in determining the particle transport through a water based suspension, all gravity separators operate over a limited size range. In the case of the REFLUX™ Classifier, efficient separations can be produced across a very broad size range, from nearly 10 mm down to 10 m, however, for a given application the size range is much more limited. This study was concerned with the processing of dense minerals over a broad size range, and the need for multistage processing. Here the overflow from the first stage cascades to the second stage, incorporating coarse gangue rejection. This approach is shown to deliver remarkably high grades and recovery.INTRODUCTION The performance of the REFLUXTM Classifier (RC™) in beneficiating fine coal is well documented (Galvin, 2012). Although the technology can be applied to relatively fine particles below 0.1 mm, or coarser particles below 2.0 mm or even 8.0 mm (Galvin et al., 2010), in each case the technology is applicable to limited particle size ranges. In coal preparation, the most common size range is 0.25 to 2.0 mm, covering an eight-fold range in the particle diameter. Coal has a relatively low density, typically below 1600 kg/m3, with a significant portion below 1400 kg/m3. In water, the buoyant density difference (~ 400 kg/m3) is therefore low compared to that of gangue minerals (1600 kg/m3) by a factor of 4, enhancing the potential for separation. Thus, in coal preparation, the technology can be applied over a commensurately broader size range, typically up to eight-fold."

Jan 1, 2018