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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 N. Dhawan

In the last decades, High Pressure Grinding Roll (HPGR) has gained significant importance in hard rock processing due to numerous metallurgical benefits such as energy savings, particle weakening, preferential damage of coarse particles, and preferential comminution-liberation. There are a limited numbers of lab-scale HPGR units throughout the world. The laboratory-scale HPGR machine at the University of Utah is first-ever lab-scale machine designed by late Dr Klaus Schönert, the inventor of HPGR. This HPGR is constructed with two counter-rotating hardened tool steel rolls, each 200 mm in diameter and 100 mm in width. The HPGR unit is equipped with eight sensors and a robust control system, which serves as an ideal system for fundamental studies and lab-scale testing. In HPGR operation, throughput, energy and product size distribution are intricately linked to specific grinding pressure, roll gap and rolls speed. The nip angle existing during the operation determines the volume of feed material above the rolls that is pulled into rolls without slip. In this paper, scale-up factors and some of the existing models have been reviewed. A number of experiments have been carried out with limestone and a slag material. The influence of operating variables and their complex relationship has been studied.

Sep 1, 2012

By M. K. G. Vermaak

Kimberlite weathering has been a topic of ongoing research within De Beers for many years. Using kimberlite weathering as an alternative to crushing has many advantages e.g. power and reducing diamond breakage. Weathering could also possibly be used in conjunction with crushing just to weaken the material and reduce power consumption. These forces have driven current research to investigate whether kimberlite weathering could be utilised for these reasons. Weathering in this context does not refer to weathering over long period of time but rather to disintegration of the material in aqeous media in relative short time periods. Previous published work discussed that the presence of smectite renders kimberlite weatherable and that the amount of smectite determines the rate of weathering (Morkel and Vermaak, 2006). The current work investigates whether cation ex-change or the adsorption of organic species in the smectite interlayer could influence the observed weathering behaviour. The results show that cation exchange does take place in the presence of cation species and that the weathering behaviour can be drastically improved with especially Cu2+ cations. Concentration and time effects of the weathering was also investigated. Weathering tests with organic species such as ethanol, methanol, edta, pentanol, butanol, acetic acid and oxalic acid was performed. The results show that organic species does improve weathering but under these testing conditions was not as effective as cations.

Jan 1, 2014

By Jyotirmoy Sarma

The surface-active agent, like sodium humate, in the present systems produces a very stable suspension. Saline water up to 15% is used as a flocculating agent for recovery of water from the dispersed phase containing 1% solid. The recovered water in the presence of humate at different concentrations (0.05-0.2%) and at pH 8 also produces a stable dispersed phase of iron ore fines and tailings. The beneficiation techniques adopted in the present systems can increase ~ 2-3% iron value in the concentrate of iron ore fine, however, for tailings the increase in iron value is not observed. Keywords: beneficiation, flocculation, iron ore fines, tailings, saline water, surface-active agent

Sep 1, 2012

By Z. H. Zhang

Shizhuyuan is a world-class WO3, Mo, Bi and CaF2 poly-metallic deposit; it has rich reservation, but great difficulty in ore?s processing; thereby, for many years, it has been the target problem of beneficiation technologies. This paper, while briefly reviews its main scientific and technological advancement, pays special attention to the complete set of new technology and technical index achieved in recent years, which is characterized by using full-floatation flow-sheet as the backbone flow-sheet, explores some key factors influencing tungsten floatation, and presents a brief introduction to such new equipment as flotation column and comprehensive utilization of fluorite.

Jan 1, 2014

By H. R. Manouchehri

Sustainable development requires the optimal use of natural resources and recycling of the wastes. In fact recycling is the final productive use of obsoletes. ELVs, obsolete appliances and industrial wastes have become important resources for production of iron and steels, non-ferrous metals, and composites. Within shredding plants, these obsoletes are firstly shredded to the pieces and then processed to recycle different materials, especially ferrous and non-ferrous metals for metallurgy. Traditional and new developed mineral processing technologies are nowadays used for recycling different materials from waste effluents. Shredding and separating plants are currently recycle the wastes by make use of different technologies to mainly produce raw material for metallurgical application. However, other non-ferrous components are also treated for energy conservation and protecting environment. Currently, recovery in shredding and recycling plants maximises to 75% and about 25% of the feed is land-filled. However, recycling rate must be increased in due to the economical, environ-mental and social concerns. A comprehensive study for recycling, with especial focus on ferrous metal recovery, was sup-ported by Swedish Environmental Agency (MISTRA) to look at possibilities to increase the recycling rate and to reduce the amount of disposal. Part of this study was dedicated to study the shred-ding plant facilities and to look for possibilities to improve the quality and quantity of the shredding product streams. The aims were to improve the quality of ferrous scrap (apparent density > 0.9 and Cu<0.25%) for iron and steel production as well as having better quality for non-ferrous metals through the recycling schema, and finally to treat the shredder residue (SR) to recover metals and plastics to reduce the disposals. This paper summarises the results of sampling and conducting separation tests for improving the recovery of the ferrous and non-ferrous metals. The results indicated to be possible to obtain high quality ferrous scrap at recovery of 88%. However, the total recovery for metal scrap has reached 93%. Furthermore, test results on fine, P< 8mm, shredding residue (SR) showed promising prospect in recovery of metals and protecting environment by physical separation, i.e. electrical separation technique.

Jan 1, 2014

By O. Kökkilic

This study covers the tests to develop separation process for production of clay and colemanite rich concentrates, and aims to serve the clay and colemanite concentrates extracted from the tailing dams to the industrial applications. For this purpose, samples from the tailing dams in Kestelek Boron Plant (Turkey) with an average B2O3 content of 8%~11 % were subjected to the investigations. The separation process of hydrocyclone--to make clear the way to obtain either clean clay or cole-manite--was initially discussed. Therefore, following the gentle scrubbing (to keep the bimodal size distribution between clay and colemanite) of the tailings to disperse the slurry, two alternative multistage hydrocyclone processes; allowing to recycling the overflows or underflows to concentrate clay and colemanite were respectively tested. As a result of the preliminary tests, the multistage hydrocyclone separation in direction to the clean colemanite concentrates (recycling the underflows) gave the better separation efficiencies. So, all the parameters such as apex and vortex finder diameters and feeding pressures were examined with the multistage hydrocyclone process allowing the recycling the underflows. The detailed multistage hydrocyclone separation process of the tailing dam wastes yielded with colemanite concentrates (approx. 12 % of the feed, w/w) with B2O3 content of 35.0 % and the clay concentrates (approx. 42 % of the feed, w/w) with B2O3 content of 2.1 %. Colemanite concentrates were found good enough either to re-feed in to the separation process or to keep upgrading for final product ready to use in Industry whereas the attempts on production of light bricks from clay concentrates has failed. But it is worth to point out that these clay concentrates can be used for agricultural purposes just in the form as it is.

Jan 1, 2014

Copper nickel separation is performed by mineral processing techniques both pre and post smelting in Copper Cliff at Vale Canada?s Operations. The separation at Clarabelle Mill takes advantage of the ore mineralogy to affect a separation on the rougher concentrate where chalcopyrite and pentlandite exhibit high liberation and high recoveries thus their separation is simple although incomplete. The copper concentrate comprises only 50% of the copper in ore with the remaining copper being separated post smelting in the Matte Separation plant where the slow cooled Bessemer Matte is again treated by mineral processing operations using flotation to separate the chalcocite and heazlewoodite and magnetic separators to remove a metallic nickel alloy. This paper discusses the mineralogy, separation processes and work currently underway to improve the separation of copper from nickel in these plants.

Sep 1, 2012

By F. M. Isik

Due to not to being our own sources, some energy sources such as oil and natural gas which are used frequently, are not reliable energy sources for our country. Coal is an important energy source that Turkey also has a certain reserve as many countries have. To be able to use for many years the reserves of this source that comes from fossils, there is a great need to make more investigation and development activities on it. On behalf of using more productively the current sources, briquetting facility is represented that commenced production in The Aegean Lignite Establishment in 2005 which is in Manisa, Soma. This facility is a part of General Directorate of Turkish Coal. This facility is run by Soma Coal Establishment that works in return for royalty in a licensed field that belongs to TKI. As the demand of market for 0.5 mm dust coal diminishes, we had to accumulate and stock unmerchantable dust coal. Besides, we have intermixed 0.5- 1 mm powder coal and 0.1 ? 0.5 mm fine powder coal obtained as a result of washing in coal washer with thermic coal with low price as we could not find a client in the market. In this study, the production stages of briquette coal with high quality produced as a result of pressing by mixing 0.5- 1 mm powder coal and 0.1 ? 0.5 mm fine powder coal with molasse and lime, quality control, and data?s obtained about calories and solidity of products were presented. By briquetting of 0.5- 1 mm powder coal and 0.1 ? 0.5 mm fine powder coal washed in coal washer, it became possible to sell these coals on a high unit price and by providing the demand of coal of the market, we contributed to productivity of our firm. Keywords: briquette coal, briquetting, producing stage

Sep 1, 2012

By Ofra Damm, v du Preez, D. van Vuuren, L. Simpson, H. Chikwanda

"South Africa is the world?s second largest producer of titanium bearing minerals, but apart from producing titanium mineral concentrate to form TiO2 slag, little further value is added in South Africa to mined minerals. Various studies were undertaken by both government and the private sector in an un-coordinated manner until 2007 when the South African Department of Science and Technology (DST) planned and adopted a national strategy to establish a local titanium metal industry through the research and development of key technologies that would provide a competitive advantage to such a local industry. The strategy entailed a two-pronged approach in the development of this capability, viz. simultaneous investments in the development of high-level human capital and technology in the fields of titanium metal powder production and downstream titanium metal powder processing technologies. To date significant progress has been made to establish research and/or pilot scale facilities in the following technical areas: TiCl4 production technology, titanium powder production technology, high energy milling of titanium powder, metal injection moulding facilities, rapid production of large components using laser additive manufacturing technology, investment casting of titanium, resource efficient machining of titanium and friction stir welding of titanium. Supporting technologies are also at an advanced stage through investments in titanium powder spheroidization and direct rolling of titanium powder. The intent with investment in some of these areas is not to develop new technology per se, but rather to establish local capability that will position South Africa to collaborate with other organisations in the world so that technologies can be acquired and transferred when needed in the future."

Jan 1, 2014

By E. Alldén Öberg

In 2004, LKAB decided to start a basic engineering study in expanding its existing production lines at the Malmberget mine site. It was expected that some of the production lines would become bottlenecks with reference to capacity. In this study, the sorting plant is examined and the results show that several unit operations will be limiting under current operating conditions. An additional purpose with the study was to investigate how replacement of some machines would influence performance and if production plans for the coming years might be achieved. Steady-state simulations using the software Modsim? were extensively used to study process performance for different operating conditions, such as iron content and size distribution in run-of-mine ore. Model parameters were derived from pilot plant data and when possible from ex-isting circuits. A complication for the simulations was the lack of relevant data and therefore some of the initial results were only indicative. The result shows that installation of new screens would give a much better operation, but also new crushers would be an improvement. This, since they can be run with full crusher chamber and tighter CSS. During 2007, most of the proposed remedies were implemented and the result is that the bottle-necks are gone, and the grades and material balances are even better than what was envisioned from the simulations.

Jan 1, 2014

By W. M. Zeng

A mixed culture of moderately thermophilic microorganisms was enriched from Acid Mine Drainage (AMD) samples collected from several chalcopyrite mines in China,which can leach copper from chalcopyrite effectively. Its tolerance to chalcopyrite was brought up to 80 g/L after being adapted to gradually increased concentrations of chalcopyrite. The effects of several leaching variables on copper recovery in Stirred Tank Reactor had been investigated. The ore contained chalcopyrite (62.2%) and galena (25.6%) as the main sulfide minerals. The results of the tests show that it is possible, operating at 8% of pulp density to attain copper extraction of 75% in 44 days. The leaching rate of chalcopyrite tends to increase with the dissolution of total iron. Microscopic counts of microorganisms in the solution tend to be higher at low pH range. Furthermore, the analyses of leached residues indicate that the passivation of this chalcopyrite is mainly due to the formation of a mass of jarosite and anglesite (about 48.3% and 21.7% in residue respectively), other than elemental sulphur layer. The bacterial community composition was analyzed by using amplified ribosomal DNA restriction analysis (ARDRA). Two moderately thermophilic bacteria species were identified as Leptospi-rillum ferriphilum and Acidithiobacillus caldus, with different proportion in the bio-pulp, 67% and 33%, respectively.

Jan 1, 2014

By W. L. Jiang

Reverse-flotation technology is often applied in iron ore dressing plant, in order to enhance the quality of iron concentrate from magnetic separation. However, this technology has disadvantages in operating cost, energy consumption, and environmental protection. Developing innovative equipment to process magnetite ore more-effectively is a way to get rid of these disadvantages of reverse flotation and improve the quality of iron concentrate. This paper describes the development of Complex Flashing-Field Magnetic Cleaner, a new kind of equipment based on the principle of combination of separation in magnetic field and separation in gravity field. This innovative equipment possesses a tailor-made magnetic system and has the characteristics of a magnetic field, which can strengthen the formation of magnetic agglomerations and the dispersion of gangue minerals, improving the quality of separation. The automatic control system developed specifically for this equipment can further increase the accuracy of separation and stabilize the process. Test results showed that this equipment is reliable in operation, economically beneficial, and has large potential of application.

Jan 1, 2014

By Jingzhong Kuang, Zheyu Huang, Chuanzhou Guo, Pengfei Liu

"In this paper, scheelite and scheelite coated with Pb2+ (SC) were synthesized by chemical precipitation with the help of ultrasonic. The role of the Pb2+ on scheelite was evaluated. Additionally, the dissolution behavior of minerals and the adsorption mechanism of collectors were investigated systematically via SEM, XRD, EDS. The results indicate that the ultrasonic cavitation can promote the formation of scheelite with large particle size and high crystallinity. Due to the exchange of WO4 2- and OH-, the dissolution of scheelite are not in a 1:1 equivalent amount by chemical formula and the concentration of WO4 2- is higher than that of Ca2+ in the solution because Pb2+ promotes the transfer of WO4 2- from scheelite surface into the solution. The dissolution of scheelite is an endothermic reaction and its enthalpy reaches the maximum value of 692.59J·mol-1 at pH=8~10. But the coating of Pb2+ changes the thermal effect of scheelite in the solution and the dissolution of SC is an exothermic reaction with the dissolution enthalpy of -262.30 J·mol-1. At pH=8~10, the adsorption capacity of sodium oleate and salicylhydroxamic acid on the surface of SC is higher than that of scheelite which delivers that Pb2+ contributes to the scheelite surface dissolution and enhances the adsorption of collectors on the mineral surface, thus achieving activation.INTRODUCTIONIn modern society, tungsten is a type of quite important rare metal and also a strategic resource. Because of its low vapor pressure, high melting point, good electrical and thermal conductivity properties, it is widely applied in high-temperature technology, lighting, machine and engine construction (Zhao,Z.W, 2013; Yan, W, 2017; Ilhan, S, 2013). Both scheelite and wolframite are the major tungsten deposits. With the depletion of easily-processed wolframite, scheelite has drawn a great deal of scientific and industrial attention. Scheelite can be recovered by flotation due to the metathesis of polarity and chargeability on minerals surface via adding regulators and collectors."

Jan 1, 2018

By L. Q. Luo

SHP-F3200 wet high-intensity magnetic separator (HIMS) was successfully used to separate the complex and weakly magnetic iron ores being composed of specularite, limonite and siderite in Ji-uquan Iron and Steel (Group) Co Ltd (JISCO). It is more and more difficult to separate iron ores from gangues, such as quartz, jasperite and phyllite, as the properties of iron ores gradually become more complicated and refractory. Some technologies have been used to improve SHP-F3200 HIMS, including modifying angle of magnetic polar from 90°to 83°, cooling exciting coils by oil instead of air, adding reverse-washing device to wash off magnetic particles, adjusting the tooth-space of matrix from 5.0 mm to 3.5 mm or 2.5 mm, so as to enhance the recovery of fine iron ore particles. It is still difficult to meet the requirement for recovering more difficultly-separated iron and the demands for high-grade concentrate of iron. In this paper, after analyzing magnetic force exerting on iron ore particles within different separating sections of SHP HIMS, it is proposed to apply the flowing-film technique into the HIMS. Thus a new-type LY matrix is designed to form magnetic gradient vertically, combined with a special flowing-film feeder to improve the existing SHP HIMS. The moving pattern of magnetic particles in pulp in HIMS separation district also has been analyzed in this paper. And the test on the SHP-F700 HIMS shows, under the condition of iron ore containing 30.52% Fe, with particle size of ?0.074 mm accounting for around 75%, if applied with flow-film technique, the iron recovery will be up from 69.45% to 76.07%, by 6.62 percent, with the same grade of concentrates of iron. The calculation of iron yield of every size fraction and the tests showed that film magnetic separation (Film-MS) could promote the iron yield of each size fraction, denoting an excellent result of application of the film technique to SHP HIMS. The mechanism of the film magnetic separation technique is to convert the turbulent flow and disordered movement of dynamic mass particles in the pulp into a directional and ordered laminar flow along the surface of tooth plate so as to strengthen the separation effects.

Jan 1, 2014

By Q. R. Chen

Wet processes are commonly used in coal preparation field home and abroad. Dry coal cleaning technology is very necessary in China because more than 2/3 of coal resources deposited in arid areas, which are difficult to separate coal with wet processes. A particular interest of this article is the discussion of separation research development of dry coal cleaning in China, such as an air dense medium fluidized bed (ADMFB) beneficiation technology, a compound dry (pneumatic) separation technology and a triboelectrostatic separation technology. The fundament and importance of dry coal cleaning methods above were introduced. On the basis of analyzing parameters which influence the performance of separators, including that of structure, technologic and operating, the separation research status of dry coal cleaning methods, especially the ADMFB beneficiation technology, were discussed and reviewed. The recent developments, especially the fluidized bed beneficiation for <6mm fine coal with an external energy assisted, including a vibrated fluidized bed and a magnetically fluidized bed, and the triboelectrostatic separation for <1mm fine coal are also introduced. The study and application results in China show that dry coal cleaning technologies can efficiently beneficiate different coals with different sizes. The ADMFB can separate >6mm coarse coal with an E value of 0.05~0.08, the external energy assisted fluidized bed can separate <6mm fine coal with an E value of 0.07~0.09, the triboelectrostatic technology can efficiently separate <1mm fine coal, and the compound dry separation technology can efficiently separate >3mm coal with a easy washability. The dry coal cleaning provides an efficient and lower cost clean approach for coals distributed in arid areas.

Jan 1, 2014

By R. M. Zhao

The process conditions and mineral characters of cleaning separation stage in magnetite concentration plant are studied in the paper, and the affecting factors and the methods to increase the concentrate grade are analysed and given. The BKJ cleaning special drum magnetic separator is developed specially for the cleaning stage according to process conditions and mineral character. The separation mechanism, structure characters, separation process and excellent adaptability of BKJ special magnetic separator are described. The results in Zhangjiawa Concentration Plant show that the BKJ special drum magnetite separators play an important role in increasing the concentrate grade and improving the economic benefit.

Jan 1, 2014

By X. Q. Chen

According to the different characters of the middle-low grade bauxite, based on the normal flotation & reverse flotation technology, the author innovates the new technology which is named bi-flotation, it integrates the advantages of normal flotation & reverse flotation, while avoids their disadvantages. Take Henan middle-low grade bauxite as research object, according to the pilot experiment of bi-flotation technology, the concentrate A/S is 9.37 and the recovery of alumina is 80.18% by flotation separate the raw ore which A/S is only 4.19.

Jan 1, 2014

By Pramila Misra, Jibardhan Meher, Debadutta Das

The concentrated coal-water slurry has been receiving considerable attention recently due its ability to replace fossil fuels. Attainment of stable and concentrated slurry has been succeeded so far through several physical and chemical techniques. The present article reports the formulation and stabilization of a highly concentrated coal-water slurry formed from five varieties of non-coking coals with variable ash contents obtained from Eastern part of India, employing three varieties of starch esters, such as starch benzoate, starch formate, and starch carbamate as dispersant. The apparent viscosity of the modified coal-water slurry has been measured by varying coal loading, dispersant percentage, pH, temperature, etc. The apparent viscosity of the slurry has been found to be decreased substantially on addition of 0.8% of adsorbate in the slurry. The particle-particle interaction has been considerably decreased and stable concentrated coal-water slurry containing high weight fraction of coal (61.5-63.5%) has been achieved in each case. The slurries stay in a non-settling form for about a month with viscosity in a permissible low range. The coal-water slurry has been found to behave as a non-Newtonian liquid. Comparison of the zeta potentials of the naked and modified coals evidences that adsorption of the dispersants at coal-water interface results in inhibition of the agglomeration of coal particles through mostly steric repulsions.

Jan 1, 2014

By F. Karakas

In this investigation, one of the most energy consuming stage of the cement manufacturing process, grinding stage, was studied. The aim of the study is to reduce the energy consumption. Optimum operating parameters were determined. Experimental studies were performed at three differ-ent stages. Grinding of limestone, clay and marl which are the main components of the cement, to approximately below 90 microns, was the first stage of the cement grinding. At this stage, effect of feed size and ball charge were investigated. At the second stage, the Bond work index of clinker and additives (slag, trass, limestone and gypsum) was found separately. After forming composite cement with clinker and additives, the Bond work index of this mixture was also determined, thus the results of separate grinding and grinding of mixture were compared. The Bond work index of mixture was found as 13.59 kWh/t, while the arithmetic mean of the Bond work index values of components was 14.90 kWh/t. Finally, clinker and additives (slag, trass, limestone and gypsum) were ground under the same conditions. At this stage, laboratory type of ball mill was used in order to understand grinding characteristics of the cement components. As a result of the experiments, it was found that energy consumption for the grinding will be lowered if the mills with 38 % ~ 40 % ball charge are used in the cement grinding. Moreover, grinding with mixture of clinker and additives gave better results than separate grinding of these components in terms of energy consumption.

Jan 1, 2014