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By F. Y. Kang

There are rich resources of natural graphite in China. It would be a good opportunity to upgrade national graphite industry if natural graphite with modification is used in lithium ion battery. Micro-crystalline graphite in high purity was coated with a carbon film on the surface. The initial cycle efficiency was improved to be 89.9% and cycle stability was remarkably improved. The experiments proved that microcrystalline graphite with carbon coating have excellent electrochemical performances at low cost as anode materials for lithium-ion battery. In addition, H2SO4-GIC technique was used to prepare the natural flake graphite powders with mild-exfoliation. Sub-micro and nano pores were found in the graphite samples. In correspondence the reversible capacity, rate capacity and cycle life were improved, which would meet the demand of high-power lithium-ion battery. Natural graphite is the most promising anode material for large-scale lithium-ion batteries. The demand of modified graphite grows up greatly in the market. Microcrystalline graphite with surface coating and flake graphite with mild-exfoliation are the promising commercial anode materials for the industry of lithium ion battery.

Jan 1, 2014

By Ibrahim Alp, Duygu Dinç, Ersin Yazici, Adularya Energy and Electricity Generation and Mining Inc., Oktay Celep, Haci Deveci

Thiosulfate leaching as an environmentally benign alternative to cyanide leaching has received particular attention in recent years. Most studies have focused on thiosulfate leaching of free milling ores and, to some extent, pregrobbing ores. In this study, leaching of gold from the refractory Kaletas ore (in which gold/silver alloy is the only mode of occurrence detected) in ammoniacal thiosulfate solutions was studied. A two-level full factorial design (23) was adopted to investigate the effects of concentration of thiosulfate (0.2-1 M Na2S2O3), ammonia (0.5-1 M NH3) and copper (0.05-0.1 M CuSO4) on the extraction of gold from a ground ore (-38 µm) over a period of 24 h. Statistical analysis confirmed the leaching of gold improved with increasing concentrations of thiosulfate and ammonia. In contrast, increasing the concentration of copper in the range tested adversely affected the extraction of gold. The magnitude of effects of parameters on the gold extraction was in the order of Na2S2O3 > NH3 > CuSO4. The maximum extraction of gold (69.6%) was obtained in the presence of 1 M Na2S2O3, 1 M NH3 and 0.05 M CuSO4. The negative influence of copper on gold extraction is most likely attributed to the decomposition of thiosulfate catalyzed by copper. Concentration of thiosulfate was also identified to be statistically the most important parameter for its consumption.

Jan 1, 2014

By P. Radziszewski

In comminution research, ore breakage and wear are usually studied independently of one another. Much of this is due to the fact that wear is usually a slow process compared to ore kage. However, the abrasion wheel test used to determine the abrasive wear contribution to total steel media wear provides the opportunity to study not only abrasive wear and friction but also ore breakage. In this paper, we will explore the use of the abrasion wheel wear test device to study abrasive wear, friction and ore breakage using standard Ottawa foundry sand. We will look into the feasibility of applying the work index as well as t10methodologies to this test set-up. We will also look at how the work index results evolve with abrasive wear and friction. We will then discuss the merits of pursuing the use of this abrasion wheel test for not only wear characterization but also breakage characterization.

Jan 1, 2014

In this paper, the recovery of copper minerals and molybdenite in the rougher/scavenger banks of two separate mineral processing plants is compared with recovery in laboratory (batch) cells. A number of metallurgical surveys were conducted in two plants treating porphyry copper and molyb-denum ore. Batch flotation tests were performed on plant conditioned flotation feed slurry, in parallel with the plant metallurgical surveys. The effect of flotation feed density on recovery of copper minerals and molybdenite in the plant and batch laboratory cells was investigated. Changes in flotation pulp density had little effect on copper mineral recovery, in both plant and laboratory cells. The ultimate recovery for molybdenite, on the contrary, increased considerably when the pulp density was reduced, both at plant and laboratory scale. Recovery of copper minerals in the plant and laboratory cells was comparable, while molybdenite recovery in laboratory flotation cells was 3%~13% higher than in plant. It is hypothesised that the flotation rate of molybdenite is sensitive to cell hydrodynamic conditions (i.e. local turbulent energy dissipation) more than the flotation rate of copper. The flotation behaviour of molybdenite particles is likely to be predominantly controlled by bubble-particle collision frequency, which is enhanced in high local turbulent energy dissipation environment. For chalcopyrite, the flotation recovery is mostly determined by attachment and stability efficiencies. An increase in local turbulent energy dissipation, while increasing collision efficiency, may negatively impact on attachment and stability efficiencies. The outcomes may have a considerable impact on increasing molybdenite recovery from porphyry ores.

Jan 1, 2014

By A. P. Liu

Semi-industrial test on fine products of Meishan dressing plant was carried out with type RP80/25 high pressure roller mill produced by Homburg Corporation of Germany, and the influences of such factors as energy consumption, water containing, throughput and circulating load on rolling effect were investigated. Closed circuit experiment result showed that Meishan iron ore could be suitable for powder grinding with high pressure roller mill, and energy consumption of the operation was declined by 25%~30%, which was favorable for energy-saving, increasing production efficiency and improving grinding effects. According to above experimental results, this paper put forward the technical proposal of application of high pressure roller mill in Meishan, and pointed out some technical problems which needed to be settled urgently in technology disposal.

Jan 1, 2014

By X. L. Wang

Hydrothermal method was applied in the preparation of calcium sulfate whiskers in airtight re-actor using gypsum as primary materials. The optimum conditions of preparation are as follows: pH value 9.8~10.1, concentration 5%, material size 18.1µm, which were determined by the analysis of the diameter of CaSO4 whiskers through SEM. On these conditions a product of ultrafine CaSO4 whiskers with diameter of 0.19µm and aspect ratio of 98 is obtained. Ultrafine CaSO4 whiskers with different concentrations, modified by titanate NDZ-401, were added into polypropylene as intensifier and composites of Ultrafine CaSO4 whiskers/ polypropylene were prepared by melting-extruding method. Mechanical performance of the composites was tested and surface morphology of the composites was observed by SEM. The results indicated that impact notched izod of the composites was enhanced by 49.5% compared with pure polypropylene when 10.0% Ultrafine CaSO4 whiskers were added into polypropylene and toughening effect was very remarkable. Dispersion behaviour and interface phenomenon of Ultrafine CaSO4 whiskers in polypropylene matrix were investigated by SEM. The results indicated that Dispersion performance of Ultrafine CaSO4 whiskers modified by titanate NDZ-401 in polypropylene matrix is good, which improved mechanical performance of composites to some extent.

Jan 1, 2014

By F. H. Deist, M. P. Roberts

"The Collieries Research Laboratory of the Chamber of Mines of South Africa is developing a coherent system of programs to aid in the full spectrum of activities arising in the planning of new as well as operating mining enterprises. It is the purpose of this paper to describe the design and application of two subsystems in the complex.One of these subsystems is an initial version of a production simulator. This program draws upon a model of a mining enterprise and simulates the operational and financial aspects of a set of alternative mine production plans.These plans are specified in terms of proposed sequences of operations. Details such as reserves, production rates, resource requirements and so on, are taken from the model.Physically, the model takes the form of a cross-referenced data base, maintained by means of a general file maintenance system which is another subsystem described.The paper concludes with a description and analysis of the first practical application of the two programs."

Jan 1, 2014

This paper pays tribute to the pioneers in geomechanics, and addresses some of the most pressing issues of our time related to deep mining, and how to mitigate these issues. Solutions developed by our predecessors seem to have reached their limits as mines continue to go deeper. The International Society for Rock Mechanics (ISRM) guidelines for rock mass characterization for excavation design also require re-thinking to reflect current knowledge and experience. Thus, a whole new approach is urgently required to increase mine safety and productivity. The paper will draw on the challenges and experiences in medicine and science that have been overcome through genuine collaboration, advances in technology, and impressive funding, which can be adopted to provide solutions to contemporary geomechanics challenges for increased safety and productivity as mines continue to go deeper.

Jan 1, 2014

By M. Weir, J. R. Cutland, L A. J. Pronk van Hoogeveen

"A computer system for the design of open pits to mine stratiform orebodies has been developed for use at Nchanga Consolidated Copper Mines, Ltd. The particular requirements of such a system, for example, the accuracy of representation of geological detail and the ability to follow footwalls, arc described in this paper, together with the methods that have been adopted to satisfy them.A modified version of the Open Pit Design Program of Rio Tinto Zinc Consultants, Ltd. is incorporated in the system and the geological data are converted into a form usable by the computer by means of a pencil follower. Some of the uses which have been made of the system are described, with reference to the long- and medium-term planning of the Nchanga Open Pit, the major producing pit at Chingola Division."

Jan 1, 2014

By N. Acarkan

Slags usually contain some quantity of valuable metals. They are actually a secondary resource of metals, rather than an end-waste and have been utilized as a resource material in many areas. In addition, for some applications, slags have comparable or even better properties than their competitors. Leaching is a method for extraction of metals from copper slags. The extraction of metals such as copper and cobalt from the copper slag of Küre-Turkey, was investigated in the past decades. Fayalitic type of these copper slags containing 0.934 % Cu, 0.353 % Co and 50.91% Fe were subjected to the experimental study. As a result of mineralogical analysis of the slag sample, fayalitic type of slag was found to contain hercynite, magnetite, hematite, pyrite, chalcopyrite, covellite, bornite and metallic copper. Direct acid leaching methods were applied on the sample. Effects of leaching time, temperature and acid concentration on Cu and Co leaching recoveries were investigated in the direct acid leaching. The optimum leaching conditions were found as leaching time of 2 hours, solid/liquid ratio of 1/3, H2SO4 concentration of 125 g/L and temperature of 70 °C. At these conditions, 75.5 % of Cu, 95.6 % of Co and 70.9 % Fe were extracted. In the second stage of the leaching experiments, copper in the pregnant solution was precipitated by cementation to produce a Cu concentrate assaying 95.58 % Cu; cobalt was obtained by precipitation with H2S to produce a concentrate containing 62.10 % Co. As a result of this study a process flow sheet has been developed for recovering Cu and Co from these slags to demonstrate its economic and technological benefits.

Jan 1, 2014

By C. R. Mambote

Vanadium is an important metal that is used mainly in ferrous and non-ferrous alloys due to the high tensile strength, hardness, fatigue resistance and corrosion resistance. Vanadium consumption in the steel industry represents about 85% of the vanadium-bearing products produced worldwide. The primary sources of the metal are patronite, roscoelite, and mottramite. Vanadium has also been produced as a by-product of the uranium production program which uses carnotite ores as a source of uranium. Vanadiferous magnetite iron ores are used for producing vanadium as well. In addition, it is known that vanadium can be recovered from the ashes of crude oil and petroleum coke. The process for treating boiler residues, fly ash and petroleum coke is similar to the process used to treat spent catalysts and ores. However, some of these materials may contain high carbon that must be removed at specific stage of the operation. Several processes are available for obtaining vanadium from fly ash, such as roasting vanadium bearing materials in the presence of sodium salt. The salt roasted calcine is subsequently leached with an alkaline or acidic solution. To obtain a cal-cine from which the vanadium can subsequently be recovered, the carbon in the source materials has to be eliminated prior to the roasting process. Other processes use the conventional hydrometallurgical route, in which fly ash is leached with sulphuric acid to obtain an impure vanadium pentoxide. The impure vanadium pentoxide is then treated with a sodium carbonate solution under atmospheric conditions to subsequently precipitate vanadium as ammonium metavanadate. Actually, the salt roasting process is the only process used commercially. In the present study, the progress in the technology of vanadium extraction from secondary materials is reviewed. The perspectives and the challenges for new process development are discussed.

Jan 1, 2014

By K. Tsuchihashi, A. Kishimoto, T. Uda, Y. Kado, S. Maruyama

We recently proposed a continuous production process for titanium metal with some experimental results. In the process, titanium tetrachloride is reduced by Mg in the presences of Bi to form a Bi-Ti alloy at 900ºC. At this temperature, the obtained alloy is liquid and allows for the continuous removal of product and heat from the reaction vessel. The obtained Bi-Ti alloy was vacuum-distilled at 1000ºC for 24 hr, and 98 at % (92 wt %) titanium, which was easily crashed to powder, was obtained. Bi solvent was selected because of the highest titanium solubility at 900ºC and the moderate vapor pressure among the candidate metals (Bi, Sn, Pb, Zn, and Sb).

Jan 1, 2014

By W. Z. Zu

In proved reserves of vanadium-containing titanomagnetite in Panxi, China, iron grades of ores were 50% ~ 15%. China?s metallurgical industry departments defined the iron ores containing 50% ~ 20% TFe as exploitable resources and the extreme lean iron ores containing 20% ~ 15% TFe as temporary unexploitable resources, the extreme lean ores were as waste rejected into waste dump in mining process. This paper researched process mineralogy of the extreme lean ores, adopted mineral processing technology responded to the properties of the ores to treat the ores and obtained quality vanadium-iron concentrate, titanium concentrate and sulfur concentrate, therefore successfully utilized the extreme lean ores, changed the ores from waste resources to exploitable resources.

Jan 1, 2014

By Guadalupe Sanchez, Roel Cruz, Sergio Castro, Claudia Beltrán, Isabel Lázaro

The recovery of zinc in refineries is strongly affected by the formation of zinc ferrites during the roasting of zinc concentrates. To achieve the highest zinc recovery most of these plants operate under high acidity and high temperature conditions in their leaching circuits. However, under these conditions high iron dissolution occurs. For iron control the common practice is to precipitate it as jarosite, and calcine is normally used as neutralizing agent. This practice causes a significant loss of metal values associated with the calcine, such as zinc ferrites and silver insoluble phases. These metal values are carried by the jarosite into confined waste in many plants. In order to diminish such losses, it is necessary to use a neutralizing agent that could substitute the use of calcine. An alternative neutralizing could be the basic zinc sulfate (BZnS). This work presents the results of a laboratory analysis on the required conditions for the BZnS production from process streams of a zinc refinery plant. Neutralizing behavior of BZnS was evaluated in iron precipitation as jarosite, in order to establish the feasibility of replacing the calcine and decrease the loss of zinc and other metals values during the iron removing step of the hydrometallurgical circuit of the zinc refinery under study.

Jan 1, 2014

By A. Vilinska

Microorganisms have a tremendous influence on their environment through the transfer of energy, charge, and materials across a complex biotic mineral-solution interface. Recent developments in biotechnology have not only aided hydrometallurgical leaching operations but also shown great promise in mineral beneficiation processes. The adhesion of bacteria on minerals alters the surface properties relevant to flotation and flocculation of minerals. The biomodification of mineral surfaces occurs through the attachment of microbial cells, oxidation reactions and adsorption or chemical reaction with the metabolite products. Several types of heterotrophic and chemolithotrophic bacteria have been successfully applied in flotation and flocculation processes for the last two decades. Al-though the potential of microorganisms in minerals beneficiation has been realised by several re-searchers from their laboratory investigations, the studies were mostly confined to pure mineral systems and there is hardly any sincere effort to apply the methodologies on ores. This paper presents a brief summary of the literature in bioflotation and bioflocculation, and attempts to outline new dimensions of research for a practicable application of this technology in mineral industry.

Jan 1, 2014

By S. Jagdish

India ranks fourth in the world of iron ore production and exported 55% of the total iron ore production of 180.9 million tons in 2006-07. As per United Nations Framework Classification (UNFC), the total iron ore reserves in India is 25249 mt. This consists of about 14630 mt of Hematite ore and 10619 mt of Magnetite ore. While the deposits of magnetite iron ore are limited to the states of Karnataka, Andhra Pradesh and Tamil Nadu, hematite ore is available in abundance in Jharkhand, Orissa, Chhattisgarh, Karnataka and Goa. National Steel Policy, declared by government of India in 2005 envisages 110 million tons of steel production by 2020. This is likely to be revised upwards. Massive exploration work in iron ore is needed to convert the available resources of iron ore into reserve category. Steel Authority of India Limited (SAIL) produced more than 24.5 million tons of iron ore during 2006-07 and plans to produce 42.0 million tons per year by the year 2010-11 to meet the requirement for a hot metal production of 26.2 million tons. While processing iron ore, the challenge faced would be the reduction of the gangue materials ? alumina and silica. It is proposed to bring down alumina and silica in the iron ore to less than 2% each from the current level of 2.5%~3.5% each. Appropriate beneficiation schemes are being developed depending upon the mineralogical characteristics of iron ores at different mines in the country. The state-of-art beneficiation technologies like Hydro-cyclone, jigging, magnetic separation etc. will be incorporated. SAIL?s corporate plan envisages blast furnace burden of 15% iron ore lumps, 15% pellets and 70% sinter by 2010. This strategy opens up the opportunity of utilization of micro fines generated in the mining and beneficiation processes for pellet making. This also directs towards all together new technological approach to the beneficiation process. SAIL is planning to set-up three pelletisation plants of 2~3 mtpa capacity. Environmental issues like reduction in slime loss and utilization of dumped low-grade iron ore are very important. R&D Centre for Iron and Steel, SAIL has carried out extensive laboratory investigations in the above area. This will help in reducing the loss of valuable iron through slimes and also increase the iron ore resource base. Laboratory investigations indicate that low grade dumped ore fines with Fe: 55.5% can be upgraded to a product with Fe: 66.2% with about 48% recovery.

Jan 1, 2014

By Olli Haavisto, Heikki Häkkänen, Tommi Kauppinen, Navid Khajehzadeh

Raman analysis is a well-established method for finding the abundant minerals in an ore sample. In this study, Raman spectroscopy is tested as a method for rapid and contactless on-line mineral analysis. Rapidness might enable on-site analysis of rock drillcore, which in turn would lead to more cost-efficient solutions in mineral exploration. This paper discusses the use of Raman analysis to identify minerals and to measure their concentration. The sample set under study consists of rock drillcore collected from Agnico-Eagle Kittilä Mine, Finland. Selected parts of the sample set are measured by Raman spectroscopy and the minerals are identified using reference spectra from a public source. Moreover, the direct measurement of concentration of different minerals with the help of Non-negative least squares (NNLS) optimisation algorithm is considered. The optimisation algorithm was constructed to form a linear combination of reference spectra which best represent the measured spectrum, or an average of measured spectra, from an ore sample. The results show that NNLS can identify abundant minerals in a given sample. Also through this method of analysis the results of a traditional point-count method can be expanded: It was observed that, due to grain size, multiple minerals consistently appear in the spectra measured over an area, which means that point-count method is not a proper way to interpret the spectra. This can be seen as a new result, as formerly the discussion has attended to other methods.

Jan 1, 2014

This study examines the surface alteration and flotation behaviour of synthetic moncheite, PtPd(BiTe)2, in the presence of pentlandite. The telluride minerals contribute around 20% ~ 30% and up to 45% of the PGM present in the Platreef ore and are considered to be slow floating as there is evidence of these minerals reporting to the tailings. It was proposed that oxidation products from other minerals and grinding media would affect the mineral surface composition and floatability thereby causing inadvertent depression of moncheite due to precipitating ions. ToF-SIMS analyses (time of flight secondary ion mass spectrometry) was used to characterise the mineral surface as well as the extent of surface alteration. Microflotation was used to deter-mine the hydrophobicity of the synthetic minerals. Conditioning of moncheite in the presence of pentlandite reduced the flotation response of the + 38 -106µm size fraction from > 99% to 56%. This was due to pentlandite dissolution products (iron and nickel hydroxy species) which formed overlayers on the mineral surfaces thereby inhibiting the adsorption of collector. In addition, further grinding of these samples, with and without pentlandite conditioning showed a negative effect on recovery due to the fineness of the particle size distribution and there was no advantage gained from any possible exposure of fresh sites in the sample.

Jan 1, 2014

By Helmut Hass, Marco Ziller

"Abstract: 1 Sophia Spoortunnel Marco Ziller, Trevi S.p.A.:For the construction of 14 cross passages connecting the twin tunnels of the Sophiaspoortunnel the Artificial Ground Freezing technique was applied as temporary soil improvement. AGF by Brine and Liquid Nitrogen was implemented. Automatic data acquisition and recording systems were installed to monitor the variation of the temperatures in the soil during the freezing intervention in order to control the behaviour and the efficacy of the treatment.IntroductionThe Sophia rail tunnel is a bored tunnel with a length of 4.24 km, comprising two separate parallel tubes with an outside diameter of 9.45 m. The twin tunnels were excavated by a TBM equipped with hydroshield. Seven service shafts, approximately 30 m deep, were constructed in between the tunnels. From each shaft two cross passages were constructed connecting the shaft with both tubes, for a total of 14 cross passages.The Artificial Ground Freezing technique utilizing both the Brine and Liquid Nitrogen methods was used for temporary waterproofing and soil support to allow the excavation of the cross passages. The natural soil to be frozen was consisting in loose sand and clay under a hydrostatic pressure up to 250 kPa.For the measurement of the ground temperature. Automatic data acquisition and recording systems were installed to monitor the variation of the temperatures in the soil and at the contact with the tunnel lining. Furthermore, a comprehensive computerized system of sensors and cryogenic valves was designed and implemented in order to manage the whole Nitrogen process.Soil Main CharacteristicsThe soil stratigraphy is generally consisting in Clay (Holocene) from ground level to -15 m depth, followed by Pleistocenic Sand, from -15 to -25 m, and Clay below -25 m."

Jan 1, 2014

By N. V. Ramana Murthy

Utilisation of Low-Grade Iron Ore Fines after concentration not only helps in conservation of the mineral wealth, but also substantialsly improves the economics of iron ore mining. There has been need to develop suitable beneficiation process for upgradation of low-grade iron ores towards their rational utilisation. Presently the circuit adopted for processing iron ores has limitations in reduction of alumina. The depletion of high-grade reserves, utilisation of low-grade reserves coupled with in-creasing market pressure for improved product quality necessitates re-examination of the process flow sheets and evaluate alternative or supplemental processing routes. The main objective of the Process amenability studies for utilisation of Low-Grade Iron Ore Fines (-10mm) is to get Pellet grade concentrate with +65% Fe (min), SiO2 1.8% (max), Al2O3 1.8% (max) and other proportionate constituents by adopting suitable beneficiation techniques and to collect the relevant data (Quality and Quantity of the Products) for the process development. In an effort to formulate a conceptual process flow sheet, the Process amenability studies for utilisation of Low-Grade Iron Ore Fines (-10mm), which is lying at a mine site in India, samples were collected and taken up for the study. The efforts of R & D of NMDC are discussed in this paper. Low-Grade Iron Ore Fines (-10mm) sample assayed 60.10% Fe with 3.48% SiO2 Aland 4.48% 2O3from 40 microns to 300 microns. The sample consists of hematite as the chief ore mineral followed by minor amounts of maghemite. The gangue minerals include quartz and ferruginous clay in which quartz occurs as medium grained where as ferruginous clay occurs as fine to sub microscopic size mineral. The economical processing route evolved out of the studies finally could yield a final concentrate constituting 58.63% by weight along with Iron unit?s recovery of 63.51% assaying 65.10% Fe with 1.48% SiO2 and 1.85% Al2O3route that adopted comprises the following operations. Making slurry in a sump pump followed by grinding in close circuit with 48mesh size Screen. The -48 mesh size product was subjected o the Cycloning to remove slimes. The Cyclone Underflow product was subjected to Floatex Density Separation (FDS) to separate fine heavy minerals from the gangue minerals. The FDS Underflow was collected as concentrate. The FDS Overflow product was further subjected with Wet High Intensity Magnetic Separation (WHIMS) to recover more Iron units as magnetics. A conceptual process flow sheet was evolved, which may become the prelude to the subsequent finalisation of the process flow sheet for commercialisation.

Jan 1, 2014