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By Hamid-Reza Manouchehri

"Sustainability calls for maintenance, rational use and enhancement of natural resources as well as balance consideration of ecology, economy, and social justice. The challenges in mining industry call for a sustained global effort using the leverage of available technologies and emerging new technologies. The industry uses significant amount of energy with the highest portion in comminution. To conserve energy, attempts have been made to improve the efficiency of the conventional crushing and grinding equipment. Nevertheless, the new and energy efficient comminution technologies are favorable through a longer term strategy. Since crushers are more energy efficient than mills, it is logic to conduct part of milling, in the crushing stage. After years of research and development, Sandvik introduces a new crushing technology, VibroconeTM, to change traditional crushing concepts. The new crushing device is able to crush and grind particles with a higher reduction ratio, more than two fold, than that of conventional crushers. By implementation of the new technology, a suitable feed size for milling can be provided to conserve energy as well as media and liner consumption, to reduce milling circulating load or increase mill capacity. There are other benefits associated with this machine, one of them being providing a higher surface area. This paper discusses the performance of the machine and its applications for comminuting different ores."

Jan 1, 2014

By Chenyang Zhang, Zhigang Yin, Jianyong He, Yuehua Hu

"A lot of floatation reagents (collectors, inhibitors and regulators) for the beneficiation of copper ores have been well developed in the past century. However, it is still unclear about the micro interaction mechanism of these flotation reagents with copper ores. In this paper, the interaction mechanism of these flotation reagents with the copper atom on chalcopyrite has been systematically investigated by first principle DFT (density functional theory) calculations. Thirty-four specific common functional groups linked with the same hydrocarbon chain (ethyl) are optimized at a B3LYP/def2-TZVP level, the solvation effect was included with the SMD solvation model. The analysis of the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO) and nature bond orbital (NBO) charge of these reagents reveals their potential applications to other types of copper-bearing mineral. Further investigation of the thermodynamics calculations gives more reliable data to screen collectors or inhibitors for copper-bearing mineral. The flotation results from carefully reviewed literatures are in good agreement with the calculation results. This work might also shed new light on the development and discovery of highly efficient and selective flotation reagents with low cost based on the computational methods.INTRODUCTION Froth flotation,(Shean & Cilliers, 2011) a mineral processing approach, is applied to efficiently enrich valuable minerals from the mixture, which is achieved according to the dictinctive surface properties of minerals. In the past century, researchers have develped an aboundant of flotation reagents by extraction or synthetize, and many carefully selected reagents might die in the bench tests or the pilot tests before the pratice.(Bulatovic & SrdjanM, 2007) Generally, it involves a lot of cost and tedious works by conducting flotation tests to screen flotation reagents. Flotation reagents have been boomed robustly with the developing of the organic synthesis.(Liu, Yang, & Zhong, 2017) Reseachers found the specific properties of a reagent are determined by its functional groups and the length of the hydrocarbon, where the functional group is assigned as the adsorption site to adsorb onto mineral surfaces and the hydrocarbon chain is called as a hydrophobic group."

Jan 1, 2018

By Dilip Kumar Mohanty

In today?s world, Sustainability is the key issue before the mankind. With the ever-increasing population & unimaginable boost in industrial growth to cope up with a steady increase in demand and fast change in life style of a human being, the natural resources are exploited to such an extent that the very existence of living beings in this earth planet is threatened. In such devastating situation, the concept of Sustainability emerges out as a great savior. This concept focuses on minimum/ judicious use of natural resources, thereby preserving the resources for future generation while meeting the bare minimum requirement of the present generation. For an emerging economy like India, Mining and Mineral based industries form the back bone of our economic development. Thus, sustainability of mining and mineral processing industry has a far reaching impact on sustainable economic development of our nation. While at a macro-economic level, we have to strike a balance between economic development vis-à-vis socio-economic & environmental impacts, Industries have to ensure judicious and frugal use of natural resources by making use of energy efficient plants & machineries and adopting befitting technology for reduction & recycling of waste. In the context of the above, it would be interesting to look into the sustainability measures taken up by National Aluminium company (Nalco) at its Crushing & conveying plant at Panchpatmali Bauxite Mine, which is incidentally Asia?s largest Bauxite Mine. In the backdrop of the above stated facts, in this paper the authors make an attempt to bring out the sustainability issues in areas of energy conservation, environmental impact/pollution vis-a-vis mitigation measures adopted in crusher & conveyor plant of Panchpatmali Bauxite Mine & CSR / peripheral developmental activities undertaken by Nalco to mitigate the socio- economic impacts. Keywords: sustainability, energy efficiency, recycle, csr, peripheral development

Sep 1, 2012

By V. Panayotov

Slag and by-products of metallurgy bear valuable components and their processing raises an in-creasing interest. Coke and iron have to be separated and other components have to be depressed, in order to obtain sellable high quality copper concentrates. Use of classical mineral processing technologies, such as magnetic separation, sulphidization, hydrometallurgy, etc. yields copper concentrates with grade of 4%~6% Cu. Copper is lost in tailings and the whole technological cycle is low profitable. Technology proposed applies an electrochemical treatment of the industrial water entering the flotation cycle. Iron and iron compounds that do not bear Cu, coke and gangue materials are depressed during the copper flotation. Copper concentrate of grade of 9.8%~10% Cu is obtained at simultaneous increase of Ag recovery by 8%~10%. As a result company profitableness is increased. Technology proposed is easy to implement, it does not require changes in the existing technology flow-sheet, and additional investment is low. The flotation process can be aided by a specially developed system for real-time analysis of the obtained copper concentrate which allows in-time corrections in the flotation parameters and entire process control. Applied flotation schemes, technological parameters and results obtained are described.

Jan 1, 2014

The air recovery from a flotation cell is the fraction of inlet air which overflows the weir as un-broken bubbles. The air recovery is an important factor in froth phase phenomena; such as gangue entrainment and froth recovery. Increasing the air recovery, results in a higher recovery of attached mineral particles. Air recovery can be measured experimentally on plant using image processing of the top surface of an overflowing froth. The air recovery is directly linked to froth stability and the bursting rate of the bubbles at the froth surface, making it very difficult to predict. Experimental results show a very strong correlation between the superficial velocity of the inlet air and the superficial velocity of the air leaving the cell through the froth surface due to bursting, calculated from the experimentally measured air recovery. This correlation holds over multiple banks from different plants. Development of a power law equation around the inlet air velocity and the bubble solids loading on the froth surface allows the superficial air velocity through the top surface of the froth to be predicted, and from this the air recovery. This model is valid for use when operating beyond the peak in air recovery.

Jan 1, 2014

By P. Spolaore

In the frame of Bioshale FP6 project, the bioprocessing of a polymetallic and polymineral concentrate produced in an industrial operation in Lubin, Poland, was assessed. Following successful batch culture tests, processing in continuous conditions was tested to determine the main specifications for the application of the stirred-tank technology to this sulphide concentrate from black shale ores. The experimental work was carried out in a laboratory-scale unit consisting of 3 stirred tanks (50L or 20L) using an acidophilic and moderate thermophilic bacterial population. Different configurations of the unit and key operating parameters were tested (nutrient medium composition, solids concentration, rates of agitation and aeration). Scientific and technical approaches, such as bacterial community structure and mineralogical analysis were implemented in order to better understand the chemical and biochemical reactions occurring in the system. Using the data produced during the continuous operation, downstream processing assessment for both copper and silver recovery was also carried out. The best copper recovery obtained in the continuous operation was 92% and a hot brine leaching of the bioleach residue (PLINT process) allowed to recover 92% of the silver. A preliminary tech-no-economic evaluation of Lubin concentrate bioprocessing including bioleaching, copper and silver recoveries demonstrated the potential economic feasibility. Recovery of silver plays an important role in the economy of the process. This study presents promising values to further investigate this bioprocessing option.

Jan 1, 2014

By Ashok Kumar, Subhadra Sen Dr. Rashmi Kumari, D. P. Chakraborty, Ajay kumar Gupta

The blast furnace coke quality depends on the characteristics of coal blend, pre-carbonization techniques adopted such as stamping, vibro-compaction etc., and coking conditions. Of the above, coal blend plays a significant role in the production of quality coke. Furthermore, the quality of the blend depends on the quality of individual coals and their interaction making up the blend. During transportation and stockpiling, coal is in contact with air for periods of time that sometimes may exceed several months. During this time, reaction with oxygen in the presence of water, sunlight and possibly elevated temperatures may take place. The resulting weathered coal suffers some alteration in its technological properties, which in turn affects coke quality for Blast Furnace operation adversely. In this work, two coals belong two prime hard coking and hard coking categories, namely Illawarra & Tahmoor, were selected and kept in a separate stock pile for a period of 120 days. These coals were characterized in terms of proximate, rheological & petrography properties at a regular frequency. This report summarizes the impact of weathering on the coking behaviour of these two coals in terms of properties as mentioned above. However, the rate of loss depends on coal rank and storage conditions. This has been seen through this study that the loss depends on coal rank and storage conditions. Deterioration of rheological and petrographic properties were seen higher for low-rank coals, like in this study Tahmoor, which is a low rank coal, compared to Illawarra showed higher degree of coking property degradation within the same time period under identical environmental conditions. Low-rank coal deteriorates at a faster rate because low-rank coal is dominated by free radicals that easily react with oxygen, resulting in the creation of various carbonyl groups and weathered vitrinite. Based on the results obtained in this study, size of stock piles for different qualities of coals to be maintained, at a specific time, can be determined and recommended, so that target coke quality is always achieved.

Jan 1, 2018

By Majid Saghaeian, Rasool Hejazi, Parisa Ghobadi

"Pulp handling in mineral processing circuits is very complicated due to its inherent different specifications compared with other fluids such as water. Because any variation in ore property (e.g. size and abrasion index) and pulp specification (e.g. density, solid content and pressure) causes problem in this part and reduces the plant availability and throughput as a result. The most common issues in the hose system are sumps and pipe-line blockage, wearing of the pumps impeller and liner, and pipe tearing specially at elbows and bends. High pressure grinding roll (HPGR) is employed in a closed circuit with a screen as the first stage of grinding in Zarand Iranian Steel Complex (ZISCO). Wearing of the pump and pipeline transferring the screen undersize stream was the main problem from the plant commissioning. The plant couldn't achieve to the design capacity because of this defect. Although various practical solutions such as improving the pipes and impeller material quality and eliminating the elbows, as much as possible, were done in order to downtime minimizing, but damages didn’t vanish. Since HPGR discharge contains somewhat rough and abrasive particles, the mentioned modifications didn't effective very much. Therefore, converting of the wet screen to dry and using of belt conveyor to the screen undersize handling was employed based on the plant capability evaluation and experimental and pilot trial results. Although this reformation imposed another additional cost (for conveyor system), but it had significant advantages such as increasing the plant availability up to 96%, reducing the operating costs of the wear parts, providing more stable operating condition for the HPGR performance and decreasing abrasion rate of the HPGR rolls liner because of the lower moist feed."

Jan 1, 2014

By Achilles Dutra, Everton Santos, José Oliveira

The beneficiation of phosphate ores by froth flotation is the most efficient process used to separate apatite from gangue minerals like calcite, dolomite and quartz. However, the similarity of surface properties between apatite and calcite generally lead to non-selective adsorption of reagents, rendering the selective separation of these minerals a worldwide problem. The phosphate deposit of Itataia, State of Ceará, Brazil, studied in the present work, presents a complex mineralogical composition having uranium associated with the apatite mineral. The main gangue minerals are calcite and quartz. The bulk flotation of apatite and calcite with anionic collectors in an alkaline medium followed by the selective flotation of calcite at pH 5.5 using phosphoric acid as well as citric acid as depressant have been suggested for this ore. This paper presents the results of contact angle measurements obtained using jojoba oil, a natural reagent composed mainly of gadoleic acid (C20:1) and long-chain fatty alcohols (eicosenol and docosenol), as an alternative collector for the selective separation of apatite and calcite minerals. The hydrophobicity studies were carried out using a computer controlled contact angle goniometer. Additionally, the collector adsorption was evaluated via electrophoretic mobility and FTIR measurements. The results indicated that a high selectivity can be obtained by using jojoba oil as collector in a slightly acid pH range, without the use of depressant. The best results were achieved with a jojoba oil concentration of 200 mg.L-1 at pH 6.5, where the apatite was fully hydrophilic and calcite showed a high hydrophobicity (? > 60 º).

Jan 1, 2014

By F. Ngoroma

Concentrators processing PGM bearing ores make use of polysaccharide depressants to reduce the recovery of the undesired naturally floatable gangue minerals, mainly silicates, present in the ore. Recent work has shown that high depressant dosages can completely depress naturally floatable gangue and thus prevent it from reporting to the concentrate. These high depressant dosages can, however, have a negative effect on the recovery of valuable minerals present in the ore by reducing the stability of the froth. In order to counterbalance the effects of depressant addition, frothers are added. It is, however, preferable to maintain independent control over bubble size and froth stability which is difficult to achieve with only one frother. An alternative strategy is, to use a blend of frothers, e.g. a weaker frother in combination with a stronger frother. Such a system allows an additional degree of freedom: changing the ratio of the two frothers, that would provide more independent control of bubble size and froth stability. This study demonstrates, through the use of batch flotation tests, how blending low molecular weight alcohols with commercially available frothers impact the solids and water recovery, as well as the valuable mineral recovery and concentrate grade in different PGM ores. Higher water and solids recoveries together with higher valuable mineral recoveries (>90% copper and >70% nickel) were obtained from tests using frother blends.

Sep 1, 2012

By J. D. Miller, C. L. Lin

In general, x-ray computed tomographic (CT) techniques are able to provide 3D images of the internal structure of opaque materials in a nondestructive manner. The unique cone beam geometry allows acquisition of all 2D projections with only one rotation of the sample thus providing for fast data acquisition and better x-ray utilization, as a complete 2-D detector array receives the cone-shaped flux of rays. Thus, an isotropic 3D volume can be reconstructed without the mechanical translation and the stacking of sequential slices as is the case for more conventional CT scanners. In this regard, a state-of-the-art, custom designed xray microtomography facility to provide very detailed 3D spatial analysis of multiphase particles has been installed and is in operation at the University of Utah. The reconstructed 3D tomographic volume allows for an adjustable spatial resolution from 5 to 20 microns for sample dimensions from 10 to 40 mm in diameter, respectively. Utilization of this custom designed cone-beam x-ray microtomography system is discussed. Applications described include: coal washability analysis for the design and operation of coal preparation plants, liberation analysis for evaluation of grinding practice and separation efficiency, mineral exposure analysis for prediction of the ultimate recovery from heap leaching operations, and analysis of the pore structure network of packed particle beds for simulation of flow through such porous structures as encountered in filtration and heap leaching.

Jan 1, 2003

By E. Hulthén

Cone crushers are used in the mineral, mining, and aggregate industry for fragmentation of rock materials. Control systems for cone crusher settings are widely used to compensate for wear and to protect the machines. The eccentric speed in a cone crusher affects the number of compressions the material is exposed to and thus the particle size distribution of the product. Eccentric speed also affects crusher capacity. However, the speed of the crusher is mostly fixed, because speed changes must be made by shifting pulleys, a process which is quite time-consuming. By applying a frequency converter, which has decreased in cost during recent years, it has become possible to adjust the speed continuously. By also applying mass-flow sensors to the process, the crusher can be run optimally to yield the most sellable products in a given moment. Existing systems normally only protect the machine. The sensors can be mass-flow meters, e.g., conveyor-belt scales. To analyze data from the process and calculate the appropriate value for the speed, an algorithm has been developed. The developed algorithm was tested and evolved at a crushing plant for aggregates that produces around 350 kton a year. The algorithm was implemented in a computer that could communicate with the frequency controller, retrieve data from four mass-flow meters, and also interact with the opera-tor. The computer was reachable over the Internet for the researchers at Chalmers and the algorithm was tuned and improved on-line. The result is a crushing stage that consistently and maximally produces the most desirable product. The performance (yield of required products) increased by 4%. As a bonus, the lifetime of the mantles increased 27% on the evaluated crusher.

Jan 1, 2014

By Jacek Kolacz

"Comex has carried out an extensive research work related to optimising sensor based sorting systems. The main target was to achieve efficient separation and maintain high capacity of the process. Eventually, the operating cost of the sorting process was investigated in terms of potential industrial applications and possible replacement of the existing traditional processing equipment. The study included an influence of the following factors on the separation efficiency: capacity, particle size and distribution, particle shape, material properties like colour, density and composition, as well as percentage of the rejected fraction. The above factors were also considered in the calculation models for the operating cost of the sorting process. In addition, other elements were considered like compressed air cost, cost of energy, labour cost, and necessary service and maintenance cost. All these elements were implemented into the calculation model allowing quick and effective evaluation of the major parameters for sorting applications. Finally, the study was carried out for two popular sorting principles: visible light sorting utilising differences in color, texture and shape and X-ray sorting using differences in density and chemical composition. GENERAL INFORMATION ABOUT SORTING POSSIBILITIES Application of the sensor based sorting systems, without any doubt, brings a lot of possible advantages in many mineral operations. The main advantage of the new system is related to its universality and at the same time very sophisticated image processing functions, which can be carried out in the same processing unit (Kolacz, 2014). Figure 1 shows the CXR-1000 system from Comex with 1 m belt width, in the configuration where many different analysed parameters can be used to provide particle separation. The image analysis system includes a camera installed either over the transport belt conveyor or at its discharge end. The system includes the X-ray attenuation analysis realized by the XRT system in the central part of the conveyor belt. The sorting system can be used with both optical and XRT analysis or separately depending on an application."

Jan 1, 2018

By Evgeni Visariev

In Copper smelter Aurubis Bulgaria, the copper in slag from the Flash furnace and the Converters is recovered by flotation. The scheme of slag processing is crushing, two stage grinding (autogenous and ball) and flotation. Till 2010 the grinding cycle in the plant was in two stages ? the first stage was AG Mill 70?23 working with a classifier and the second stage was ball mill 3.6/5.5 working with a hydrocyclone. In 2010 a new AG Mill 65x78 with hydrocyclone was put in operation in order to increase throughput of the plant. The second stage of the grinding cycle is with the same ball mill. The Old AG mill processed 55-60 t/h slag with particle size -0.071 mm 75% or over 75 t/h with particle size -0.071 mm 35-40 %. The new AG Mill was designed for throughput 105 t/h with particle size -0.071 mm over 70 %. After the start up there were some problems with the equipment ? block up of AG Mill?s grate and pumps for feeding of the hydrocyclone. For optimization of the process a lot of general tests were made. One of the main problem was a wearing of the sand nozzles. Different materials (rubber, ceramic, metallic) for the sand nozzles were tested. The openings of the grate were changed. This paper presents: ? the optimal technological parameters of the old and the new working scheme; ? how the technological parameters of the new working scheme change when the hydrocyclone works with different nozzles; ? the effect of the change of the grate openings; ? the problems with the increase of the circulating load; ? a final decisions for improvement of the grinding cycle work. Keywords: spigot, wearing, classification, effectiveness, circulating load, autogenous, mill

Sep 1, 2012

By J-P Franzidis, P. O. Gyebi

"Coal-water mixtures (CWM) of concentrated fine coal may be transported in pipelines but this is influenced by both CWM rheology and stability. Here, a low viscosity is required to reduce power requirements, as well as good stability for transport and storage. The objectives of this study are to investigate the importance of surface charge, solids concentration and dispersant addition on the rheology and stability of a fine Witbank coal-water mixture (<75 m). Zeta potential, rheology and stability were measured with a Malvern Zetasizer, a AR1500EA rheometer and a static rod penetration test, respectively. Sendep 30D, Sendep 30F and Norilose 8058, all supplied by Senmin International, were used as dispersants, at dosages of between 0.1 to 0.5% dry coal (w/w). Solids concentration was varied from 10 to 58% (w/w). The zeta potential was found to be positive at low pH and decreased sharply with increasing pH to a minimum of -50 mV at pH 10. The zeta potential decreased with increasing dispersant concentration for all dispersants. The lowest zeta potential of -63 mV was obtained for Norilose 8058 at a dosage of 0.3%. CWM rheology was Newtonian at lower solids concentrations but became non-Newtonian at solids concentrations over 40% (w/w), with an initial yield stress and pseudo plastic behavior. The yield stress decreased sharply with increasing dispersant concentration for all dispersants. The lowest yield stress was obtained for Norilose 8058. The addition of dispersants resulted in significant improvements in stability. A penetration ratio of over 70% was obtained for Norilose 8058 after 10 days. In summary, the addition of dispersants resulted in a decrease in the zeta potential which increased the electrostatic repulsive forces between particles, thus improving both CWM rheology and static stability.INTRODUCTION Coal Water Mixtures South Africa’s energy economy depends heavily on coal. It accounts for about 70% of primary energy consumption, 93% of electricity generation and 30% of liquid petroleum fuels (Eberhard, 2011). The transportation of coal to export markets and power generation stations is a problem in the South African coal industry due to ageing and inefficient rail infrastructure. This problem is intensified by the long distance of coal haulage, delays in the time required to load and unload wagons, and environmental challenges related to air pollution and water contamination. Fine coal may be transported more efficiently and economically in a pipeline as a highly concentrated coal water mixture (CWM). Typically a fine coal CWM will contain 60-75% coal, 25-40% water and nearly 1% of dispersing additives (Atesok et al., 2005; Dincer et al., 2003). However, the transport of CWMs in pipelines is strongly influenced by both CWM rheology and stability. Here, a low viscosity is required to reduce power requirements, as well as good stability for transport and storage. These quantities are affected by the coal composition/mineralogy, solids concentration, particle size and size distribution, particle shape, inter-particle forces and dispersant type and dosage (Laskowski, 2001)."

Jan 1, 2018

By J. H. Starkey

SAGDesignTM Testing for grinding mill design was introduced commercially in 2004. Up to January 2008, 18 projects have been completed and 99 samples have been tested using this method. Two papers have been published describing the patented test procedure and one of these shows how the results compare with other grinding test methods. This paper will briefly discuss the theory on which this technology is based, and explain the procedures used to develop the calibration equation. Case studies are also included to demonstrate the effectiveness of the test work being done. These case studies show how the SAGDesign test is being used today: to design new grinding circuits for commercial full scale use; to calculate throughput in existing mills for production planning; and to accurately define grinding mill requirements at the scoping, pre-feasibility or feasibility study stage of project development, in order to economically identify the size and cost of the grinding mills that will be needed for the project. This is important because if the full rec-ommended SAGDesign testing program is done at an early stage in the project, the definitive cost for a guaranteed throughput, grinding mill design (by Outotec if their mills are purchased) is available. New grinding mill design for final engineering will be represented by the test work done on the Climax Molybdenum Project for Phelps Dodge (now FMI) in Colorado, USA. The SAG mill and ball mill for Climax are now in fabrication with project start up in late 2009. Next, the sizing of grinding mills at the scoping, pre-feasibility or feasibility study stage of mine development will be represented by a large metal mining property in Russia. Finally, calculation of the throughput for existing mills will be represented by work done at a base metal mine, in eastern Canada. Test work for designing SAG mills is now done in four laboratories at the time this paper was written. One in the USA at Dawson Metallurgical Laboratories, Inc. in Salt Lake City, two in Russia at the TOMS Research and Design Institute and at the Irgiredmet Research Institute, both in Irkutsk, and a fourth mill has been installed in Australia at AMMTEC Limited?s lab in Perth. A fifth SAGDesign test mill for radioactive ores has been built by Starkey & Associates, specifically for testing uranium ores and can be moved to any licensed lab in the world on a project basis.

Jan 1, 2014

By Manuel Diaz

"In these difficult times for the mining world, mainly due to the global uncertainty about metal prices and the increased activity of opponents to the mining industry, it is essential that mining companies focus on efforts and strategies that will give them the most flexibility to succeed under the fury of these phenomena. The careful management of systems to control costs, and indicators to measure with great precision actual variations in costs and cash flows, are essential to adequately manage the uncertainty. Similarly, clear corporate and regional strategies designed to maximize cash flow and operating margin will allow the company to be better prepared to face any negative situations caused by declining metals prices, stricter government regulations and increasing social pressure. Gold Fields Limited, a corporation of South African origin and with more than 100 years in the gold mining business, has developed the ability to adapt to large changes generated by different global crisis throughout its history. This occasion will be no different. Given the critical situation of the mining industry in the world today, Gold Fields has embarked on a re-structuring plan at global level that will allow much closer control and real efficiency of production costs. This plan includes the creation of regional business units that allow greater independence for each region while still preserving the standards and cultural values of the Corporation. This presentation will explain why we believe that this approach combines the best aspects of the two styles of business, and what are the expected results. In the Americas Region, Gold Fields currently operates Cerro Corona, in Peru. In addition, the company is considering opportunities for growth in Chile, Brazil, Mexico and Canada."

Jan 1, 2014

By Leopoldo Gutierrez

Eight oil sand ores with the bitumen content ranging between 3.6 and 15 wt.% and the fines content (-44 micrometers size fraction) between 9 and 69 vol.% were subjected to the standard alkali extraction test used to measure the degree of oxidation of metallurgical coals. The results showed that there is a strong correlation between the absorbance of extracted solutions at a wavelength of 520 nm and the ratio of the fines content to the bitumen content. The latter factor is directly relevant to assessing the extractability of bitumen from oil sand ores. Bitumen extraction tests showed that the bitumen recovery decreased from 90 % to 30 % when the absorbance at 520 nm increased from 0.23 to 0.64. A comparison of the UV/visible spectra of solutions obtained from the alkali extraction tests with solutions of Aldrich Humic Acids suggest that low bitumen/high fines oil sand ores release substantial amounts of organic matter very similar, if not identical, to humic acids. In contrast, high-bitumen and low-fines ores do not release as much of the organic matter, and UV spectra of these leached substances are quite different from those of humic acids. Overall, the results show that chemical composition of bitumen in the tested ores varies greatly with ore type and oxidation, and that the alkali extraction test is a promising technique to quickly assess the extractability of bitumen from a given ore type.

Sep 1, 2012

By P. K. Sen, Mrinal K. Ghose

Tailing slurry is usually abrasive and possesses high viscosity. This paper examines the existing iron ore beneficiation process and focuses on some of the key environmental issues related to the disposal of tailings. It identifies that almost 32% of the iron ore extracted ends up as tailings and they are usually disposed in slurry form in tailing ponds. By the year 2000, 27 Mt of iron ore tailings were generated in India, which has become one of the biggest waste handling problems to the industry. Characteristics of the tailings vary widely. So the physical nature of tailings cannot be considered separately in isolation without considering the mill effluent from the beneficiation plant. In the present investigation, studies were carried out in three iron ore mines in India to evaluate the characteristics of tailings from the beneficiation plant. The tailing samples were collected from different locations during a time period of one year and analyzed. The results will be discussed and the characteristics of the tailings have been evaluated. The disposal system of tailings at the three mines was evaluated. The research on the settling characteristics of tailings indicates that the area provided in the existing tailing ponds in India is much more than that of the experimental results. This paper concludes that sedimentation tests are essential to design appropriate tailings pond with respect to size. In the proposed scheme it is suggested that an additional unit process, i.e. sedimentation tank be added to the process before the disposal of tailings to the tailing pond.

Jan 1, 2003

By Baidyanath Mandal

Technology in the solid-liquid separation industry has evolved rapidly during the last fifty years and from the beginning, DIEMME Filtration has played a very important role in this evolutionary process by developing innovative solutions, which are used for a diverse range of industrial applications. Since the last decade, we find more and more examples of filter presses employed in the mining & mineral processing field, where high performances in terms of productivity, dewatering capacity and mechanical strength even in extreme working conditions are required. Mainly the requirement of such high quality equipment comes from the Process, however in few cases the reason could be linked with the environment. For stringent process applications like Mineral Concentrates dewatering & leached Slurry Filtration, it requires a high quality & extremely reliable equipment. In these applications, since many years industries are achieving the desired result by using Diemme Filter Presses. Also, recently, due to stringent environment practices are been applied globally, industries needs equipments which could dewater a high amount of residues / tailings with minimal moisture content in the filtered cake. In comparison to all the conventional dewatering equipments, Diemme Filter Presses are most efficient for these kind of product & applications. Diemme Filtration is a highly professional & technological company with several decades of experience in designing equipment for mineral processing. We take up each project as separate & design and manufacture equipment based on individual process or project requirement. This presentation will be focused on the Solid-Liquid separation technologies & equipment Diemme Filtration offers to the mineral processing Industries. It consists of Diemme?s History, Global Network, Technologies & Expertise, R & D Capabilities, Manufacturing Range, Some Applications & results on different mineral processing. Keywords: solid-liquid separation, filtration, dewatering, filter press

Sep 1, 2012