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By V. A. Chanturiya

In Pt- and Au-keeping complex ores processing, about 10% ~ 15% of noble metals are lost with true tailings that are due to low floatability of Pt- and Au-keeping minerals by the conventional collectors. With the aim to achieve the effective recovery of noble metals at flotation of Pt-Cu-Ni and Au-keeping ores organic complex reagents keeping electron-donating atoms of nitrogen, oxygen, sulfur or phosphorus may be offered as selective collectors for the indicated minerals. These rea-gents tend to form complex compounds with PGM. Besides this, Cu-Ni-Pt and complex Pt and Au carbonated mica ores are characterized by finely disseminated (up to nanometer size) mineral forms of Pt in multivalent states. In this connection, the use of a combination of the strong ionic collectors with nonionic reactants that are capable to derivate complex compounds with multivalent PGM seems to be expedient for this type of ores. In the research new complex reactants were tested such as cyclic alkylene-trithiocarbonates, oxyalkyl butylxanthogen acid ethers, a combination of the collectors ? mercaptobenzothiazole (MBT) and dialkyldithiophosphates (DTP). Sorption and flotation tests were made with monomine-ralic samples of chalcopyrite, pentlandite, pyrrhotite, pyrite, and Pt-Cu-Ni sulfide ore samples. Sorption properties were examined by the extractive UV spectrophotometric method and potentiometric measurements. To indicate a structure of modified xanthate solutions the method of a thin-layer chromatography (TLC) was applied. The chromatographic behavior of the basic components of modified xanthate solution ? ButX, cyclic propylene-trithiocarbonate (PTTC), diethyl-dithiocarbamate (DEDC) and the product of its modification ? oxypropyl-S-ether of dithiocarbamatic acid was studied on plates ?Silufol UV ? 254?. The composition of organic solvents and its ratio in a mobile phase was deter-mined for simultaneous chromatography of the main components of a reaction mixture. It was found that operating selectivity of MBT, DTP and cyclic alkylene-trithiocarbonates incorporated in modified xanthate in relation to Pt-Cu-Ni and Au-containing sulfide minerals might be explained by an electoral sorption of this nonionic collector on a surface of the minerals studied. It was demonstrated that the application new reagent modes with the use of a combination of designed complex reactants helped to increase the extraction index of Pt- and Au-keeping minerals from complicated ores.

Jan 1, 2014

By F. Y. Kang

Graphite with layers structure is easily to form graphite intercalation compounds (GICs) by means of intercalation reactions due to the weak cohesion force among carbon layers, van der Waal?s interactions. By controlling the oxidation-intercalation, high quality exfoliated graphite with low residual sulfur content and MClx-GICs (M=Fe, Co, Ni, Cu, Zn) powder for electromagnetic wave absorbing and shielding materials have been invented. The expansion volume of expandable graphite can be larger than 160 mL/g while the residual sulfur content is less than 800 ppm. The MClx-GICs powder can shield infrared ray and laser completely up to 15 min. We have also in-vented exfoliated graphite for heavy oil adsorption and mild-expansion exfoliated graphite for anode materials in lithium ion battery by controlling the intercalation/de-intercalation. The exfoliated graphite can adsorb heavy oil up to 80 g/g, it also exhibits better performance than commercial active carbon in sewage treatment. The mild-expansion exfoliated graphite as anode material shows high capacity of 370 mAh/g and good cycle performance.

Jan 1, 2014

By C. H. Zhou

Cryogenic grinding of Printed Circuit Board will bring less pollution, reduce energy costs, smaller particles, regular particle size, efficient process, separation various materials due to different fracture toughness. Systemic studies of recycling discarded Printed Circuit Board (PCB) by low-temperature modification and cryogenic grinding have been made in this paper. Firstly test mechanical property of PCB at different low-temperature, including impact strength, flexural strength, and shear strength. Do experiment on the power consumption of different cooling temperature, The results show that the average power consumption is lower between -30? to -60? and the average power is decrease in evidence at -30?. Use ZKB type double roll shear crusher to crush PCB to 20mm×20mm particle size, in a temperature range of -10 ~ -30? Used R type mill to grind sample to minus 3mm under different working condition, the average power consumption is decrease in evidence from -10 ? to -30 ?, power consumption is the lest at rotational speed is 1180rpm.

Jan 1, 2014

By Tyler Acorn, Tristan Worsey

A dozer operator at a surface gold mine accidentally drove a D10 off the side of a highwall. The blade of the dozer caught on the lip of a catch bench 60 ft. (18.3 m), down stopping its descent. The operator scrambled to safety in fear that the dozer would not hold.

Jan 1, 2014

By C. Lemmer

The resolution with which the different categories of resources are forecast for Witwatersrand gold reefs should ideally tie in with block sizes that are optimal in terms of the variability structures of the reefs. A tool, called the ?variancegram?, is proposed as a basis for block size choice. A variancegram is intrinsic to the particular reef and mine concerned. A further requirement is the ability to attach global confidence limits to weighted average estimates built up from combinations of local kriged estimates. Approximations to derive global kriging variances based on variables derived from local kriging deliver hugely inflated results if ordinary kriging is used, and markedly better, but not accurate, values if simple kriging is used. These approximations improve as the number of samples used in kriging each block is increased. It is shown that the behaviour of the different components of the global kriging variance with increasing number of samples, all differs, but they all link to the variancegram for the particular reef. The variancegram can thus be used to correct the different components to the values they would have had if all samples were used in kriging each block, and so deliver the ?correct? global kriging variance, even though only a limited number of samples were used in kriging each block. The desirability of having very stable solutions implemented in production systems is taken into account in the proposals. It is anticipated that the same variancegram findings will also hold for other densely sampled deposits, but this remains to be investigated.

Jan 1, 2014

By J. Gotor, C. Frias, E. Delgado

The Iberian Pyrite Belt (IPB) is one of the world's largest reserves of primary sulphides containing base metals (Cu, Zn, Pb), precious metals and some special metals such as indium. Estimated resources are over 1,500 million tonnes of volcanogenic massive sulphide ores. From 1980´s Europe lives the decline in its mines mainly motivated by the low price of the metals. One aspect that contributed equally to this was the ecological disaster produced by the discharge of more than seven million tonnes from the tailings dam of Boliden-Apirsa (Aznalcollar) in 1998. Today the situation is different; the companies present in the IPB have given evidence that it is possible to reconcile mining projects and care on the environment, and the regional authorities are opening a public tender to re-start Aznalcollar mine. A new challenging era has been started at this Spanish/Portuguese mining area. This paper presents the results and preliminary economics of a project devoted to IPB primary sulphides processing through different technology approach, e.g. conventional selective flotation against bulk flotation or mixed metals flotation combined with hydrometallurgical processing.

Jan 1, 2014

By Vladko Panayotov, Marinela Panayotova

"Recently, in order to extract metals, the industry is trying to process old metallurgical slag. The material requires very fine grinding that results in enhanced slime-formation. This in turn leads to problems in the course of the flotation process and to a loss of metal. In addition, it causes difficulties in the wastewater treatment aimed at water reuse. The aggregation and separation of the fine particles and their further subjecting to mineral processing would result in more efficient use of raw materials. Closing the water cycle also would be facilitated. The paper presents results from studying sixteen flocculation reagents, commercially available for treating municipal wastewater, including products based on nanotechnology, for their ability to rend the production wastewater in suitable for reuse in the flotation. It turned out that, from all studied reagents, the cationic C-587 is suitable for the purpose. Some of reagents were studied for their ability to flocculate selectively, in presence of coke fines, rich in copper fines which are produced at grinding of a slag from lead-zinc metallurgy. Most promising reagents are chosen, based on the chemical analysis of the flocculated materials. Open-cycle rough copper flotation experiments with the flocculated fines and recycled wastewater gave encouraging results."

Jan 1, 2014

By I. Ngoma, Marijke Fagan, Susan Harrison, Rebecca Chiume

"Heap bioleaching is an unsaturated hydrometallurgical extraction process which is commonly applied to the recovery of copper from low grade sulfide ores as well as for preparatory treatment of gold ores. The leaching reactions occur in the liquid phase, catalysed by iron and/or sulfur oxidising micro-organisms. Contact of the mineral grains with the leaching solution is consequently essential for metal recovery. Additionally, the liquid is responsible for the transport of the liberated metal out of the heap under gravitation-driven flow. However, the highly inhomogeneous structure of the heaps coupled with low irrigation rates cause the flow to vary between being gravitationally and capillary dominated, resulting in non-uniform wetting of the ore. In this study a 132 kg agglomerated ore ‘slice’ is used to examine the effect of liquid distribution on microbial colonisation and mineral recovery in a long term bioleach (> 500 days) when irrigation from a single drip emitter source is employed. The novel setup enabled sample collection from ports positioned along the length and height of the ore bed, so that 2D maps of the degree of wetting and microbial colonisation could be generated at different times in the leach. Lateral movement of the liquid increased with bed depth; the majority of flow was below the irrigation point while the top corner of the bed that was not irrigated remained the driest region of the heap throughout the experiment duration. The lowest cell numbers were also recorded in the driest regions. Specifically, cell numbers in the top corner of the bed, 400mm from the irrigation point, remained at undetectable levels until the 283rd day measurement, in line with typical heap operation durations. This indicates that slow colonisation of the heap in the regions between irrigation points may be a significant issue in heap optimisation."

Jan 1, 2014

By B. Y. M. Bueno

Biosorption of heavy metals can be an effective process for the removal of heavy metals ions from aqueous solutions. In this study, the adsorption properties of Rhodococcus opacus biomass for Pb(II) and Cu(II) ions was investigated. The effects of initial pH, initial metal concentration and biomass concentration on biosorption efficiency were studied in a batch system. Results showed that the initial pH would play an important role in the Pb(II) and Cu(II) ions removal by R. opacus and affected the zeta potential of R. opacus. The equilibrium adsorption was reached with 60 min. The Langmuir and Freundlich models were used for describing of adsorption isotherm data. The maxi-mum adsorption capacities of biomass were determined as 94.3mgg-1 and 32.2 mgg-1 for the Pb(II) and Cu(II) ions, respectively. The experimental data fitted to pseudo second order kinetic model. Adsorption capacity of Pb(II) ions was found to be reduced by the presence of the other competing metal ions in the system. The FT-IR results of R. opacus biomass showed that biomass has different functional groups and these groups are able to react with metal ions in aqueous solution.

Jan 1, 2014

By Priscilla Aki Mori de Hanashiro, Viviane Tavares de Moraes, Denise Crocce Romano Espinosa, Hugo Hashimoto

"The LCDs are used in televisions, calculators, mobile phones, computers (laptops and tablets), video games and other electronic devices. The advancements in technology make obsolete these devices, causing excessive disposal of LCDs and therefore decreasing life span of landfills. In this context, the LCDs from LED LCD TVs arise as an additional source of waste electrical and electronic equipment (WEEE). Thus, it is essential to develop LCDs recycling methods, beginning with the LCD characterization followed by displays processing, aiming the materials separation and using some Ore Treatment Techniques, and finally, the recovery of indium using acid leaching. The analysis methods that will be used in this work are: Fourier Transform Infrared (FT-IR) and Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES).IntroductionLiquid Crystal Display (LCD) technology is applied in modem televisions, calculators, mobile phones, computers and a wide range of electronic devices. It has replaced Cathode Ray Tube (CRT) technology as the most advantageous display product, due to lower electrical power consumption, size and weight reduction, and no radiation emission [ 1]. The constant improving of LCD screen technology reflects on its growing contribution to the amount of waste electrical and electronic equipment (WEEE): an estimated 50 million tons of WEEE are produced every year [2]. Once the most common method of its disposal are landfills, the LCD technology therefore became an environment issue [3].LCD structure is composed by components made by different materials. In order to develop a LCD recycling methodology that gives the right destination to these materials, a previous characterization stage is required. This characterization includes a disassembly process and material identification analysis. One of the LCD components is the screen, which is composed by polymeric and glass layers. The liquid crystal glass was the starting material of this study. It contains indium in the form of indium tin oxide (ITO) film. This ITO film is deposited in the glass by a sputtering process and acts as the electrode material [4,5]. It has in its composition 90% ofln203 and 10% ofSn02 [6]."

Jan 1, 2014

By Stefan Wallner, Andreas Filzwieser, Stefan Konetschnik, Reinhard Preiss, Iris Filzwieser

"Process Safety Management for METTOP means avoiding risks as far as possible - but also dealing with the residual risk by using all existing management tools or external assistance, if required. The presented paper has two parts. The first one introduces a new and very safe cooling technology for metallurgical furnaces. The second part shows how to deal with the residual risk as well as minimize it by using the tapping area of an electric arc furnace as an example.Today more and more intense furnace operations require effective cooling in order to achieve low refractory wear and good furnace lifetime, making cooling technology an important aspect of furnace operation. However, the use of water - today’s standard cooling medium - has some disadvantages, as it can cause problems both during furnace start up and operation, namely hydration problems, corrosion, and explosion.To overcome the disadvantages of water, a new cooling technology using an alternative cooling medium, namely ISIS B (a special kind of ionic liquid) was developed. The main advantage of ISIS B is the fact that no explosion occurs when this liquid comes in contact with molten metal. The working temperature range of ISIS B of 50 to 200 °C results in other advantages as there are no corrosion problems and no risks of hydration.The fact that no explosion occurs when ISIS B contacts molten metal leads to a revolutionary solution for the metallurgical industry in terms of safety. Especially in critical areas - like tap-holes - new safety standards can be achieved.Together with the TÜV Austrian Holding AG a risk analysis was done for a water cooled tap-hole as well as for a tap-hole cooled with ionic liquids. It is shown that using the new technology the risk can be decreased dramatically and the importance of a best available technology is described."

Jan 1, 2014

By Q. X. Li

The state discharge standard for arsenic-containing wastewater which is the first kind of pollution is less than 0.5 mg/L. In fact, in a certain company, the acidic arsenic-containing wastewater in non-ferrous smelting was as high as 860 mg/L, which is far beyond the state discharge standard. Obviously, the direct release of this wastewater without further treatment would result in great hazards to the ecological environment. To aim directly at the characteristics of acidic arsenic-containing wastewater, in this study, two steps of treatment including oxidation-flocculation and removal fluoride by mixing alkaline neutralization were suggested. Through analyzing various influencing factors in treatment effects, the optimum technical conditions were obtained. The sediments after treating were recyclable and the secondary pollutions can be avoided. Moreover, the results also show that, all indexes of the effluent after treating are lower than the First Grade Standard of Integrated Wastewater Discharge (GB 8978-1996). This novel method has advantages of short flow sheet, easy operation and low cost.

Jan 1, 2014

By S. V. Petrov

In recent years, heap leaching of gold is becoming wide spread due to low capital and operational costs that allows economically feasible processing of low-grade and cut-off grade ores. Currently, over 30 heap leach projects are operated in Russia. Some of the deposits treated by heap leach methods are almost depleted. Therefore, they will soon require spent heaps detoxification and reclamation. Traditionally, spent heaps are detoxified by chemical treatment. This process is characterized by relatively high kinetics and requires expensive reagents and additional equipment. The main disadvantage of this process is secondary contamination of the solutions by products of detoxification reactions and impurities contained in reagents. If there is enough time, spent heaps can be detoxified by natural degradation. The advantages of the proposed method are low operational costs due to use of existing heap leaching facilities and eliminating the need for chemicals for spent heaps detoxification. Residual concentrations of cyanides and thyocyanates in liquid phase (wet ore) of spent gold ore heaps after detoxification were 0.2~0.3 mg/L. Heavy metals were almost completely removed. The method was successfully used for detoxification of spent heaps at two gold mines.

Jan 1, 2014

By N. Hamlef

In this study, the effects of heat treatment on phase formation and surface morphology of the Cr-Pt coated system are investigated using X-ray diffraction and electron microscopy techniques. The CrPt andCr4Pt (Cr3Pt - A15 type) phases were formed after heat treatment of the coated samples. Heat treating at 1000°C renders a distinct island coating morphology that is non-continuous in nature. A diffusional model is proposed for this coated system with regards to the surface morphology formation after heat treatment.

Jan 1, 2014

By Rajendra Singh

Considering the importance of a fully mechanized depillaring operation, the Indian coal mining industry has introduced a number of such depillaring operations at depths of cover ranging from 60 m to 377 m. The overlying strata of these depillaring faces vary widely from highly laminated, weak and easily caveable to massive, strong and difficult to cave. Most of these mechanized depillaring operations were carried out in difficult site conditions, however, performance monitoring in the field has showed good production, productivity and safety results. Field studies have shown that the use of roof bolts as breaker line support for this technology worked well for moderate strength overlying roof strata, but experienced difficulties for both extremely weak and strong/massive overlying roof strata. It is observed that the performance of a breaker line support along the goaf edge deteriorated with an increase in depth of cover of the depillaring face. Practice of a straight line of extraction (single row of pillars) during the mechanized depillaring below competent roof strata experienced a considerably large hanging area inside the goaf, which needs to be managed either by induced caving of the roof strata or through an increase in width of the excavation. Observations of good performance of a fully mechanized depillaring face under highly laminated and weak strata at a shallow cover is mainly due to a faster rate of extraction. However, the mechanized depillaring underneath laminated and weak roof strata for a deep-seated coal seam was forced to go for partial extraction mainly due to strata control problems. Discussing the implications of main technical and operational differences between the conventional (semi-mechanized) and fully mechanized depillaring, this paper presents results of different strata control studies conducted at different mechanized depillaring sites with varying geo-mining conditions.

Jan 1, 2014

By O. A. Ojo, D. L. Chen, N. Zhou, J. Q. Zhang, A. K. Khan

Dual phase (DP) steels are designed to consist of hard martensite dispersed in a relatively soft ferrite matrix, which offers a favorable combination of high strength with good deformability. Fiber laser welding (FLW) is becoming increasingly important for joining advanced materials due to its flexibility and deep penetration. In this study, the microstructure of a dual phase steel, DP980, welded by FLW technique was carefully analysed. Gleeble thermo-mechanical simulation coupled with analytical transmission electron microscopy (TEM) revealed that the FLW process produced significant microstructural changes in a narrow heat affected zone (HAZ) and fusion zone (FZ), which can result in dramatic changes in mechanical properties. This is reflected in the micro-hardness profile obtained across the welded material. The salient phase transitions induced by the FLW, including the formation of new martensite grains in the upper-critical HAZ and FZ, are discussed.

Jan 1, 2014

By Y. H. Zhang

Mechanism of BK501 in desiliconization from bauxite was studied by use of flotation test, EDS, ?-potential, FTIR. Results of flotation show that almost all of diaspore can be depressed when BK501 is put into pulp ranging from pH 4~12, in the meanwhile kaolinite is slightly activated. In the light of surface analyses, it is concluded that the adsorption of reagent on the diaspore is dominant by chemical interaction. Moreover, kaolinite may float more by addition of BK501 because of flocculation.

Jan 1, 2014

By B. Dubreuil, J. -M. Lalancette, D. Lemieux

A gold bearing pyrite concentrate was treated at the pilot scale for the extraction of gold. Mineralogical analysis of the concentrates identified gold to be mainly present in the form of a solid solution in pyrite. Gold distribution resulted in a poor extraction yield of 55 % by direct cyanidation. A piloting campaign including an oxidative pre-treatment by roasting in a fluid bed was followed by treatment with halogens for gold extraction and has led to a gold extraction yield of 94%. Sulphur removal during the oxidation was very efficient at >99.5% and gold extraction by the halogens was completed within a 1 hour contact time. The piloting was performed on a 300 kg sample and used a diluted solution of hypohalites as the oxidizing agent for gold extraction. Sulphuric acid was injected in the reactor during the halogens treatment to lower pH to 2. The diluted solution of hypohalites (1-3%) was generated by electrolysis during the piloting campaign in a diaphragm-less electrolysis cell. The extracted gold was recovered via adsorption over silica and the gold depleted brine was treated for impurities removal. This brine was recycled for further gold extraction. With the recycling of water and brine, the regeneration of hypohalites and with a barren solid that is inert and stable, the Nichromet Extraction technology is a green process where the protection of the environment does not preclude profitability.

Jan 1, 2014

By X. M. Yu

A large amount of polluted sludge is produced by a nonferrous metal factory after treating waste water with lime/ferrous salt. The concentration of arsenic in the dried sludge is high to 5.84%, a toxicity test is taken on the sludge according to GB5085.3-2007 and the extraction content is 15.75mg/L, which surpasses the arsenic extraction standard [As]=5mg/L, the sludge is categorized as hazardous waste. If put outside without disposal, it would be very harmful to environments. Here we report an optimum protocol to extract arsenic; S2- alkaline liquor is utilized to treat the arsenic sludge. At 85?, 10L 7% S2- liquor is added into 1kg dried sludge and the resulting mixture is stirred for 120min at 250r/min, then separated by centrifugation and the compressed waste residue dried naturally. The average arsenic content is 1.40mg/L, lower than GB5085.3-2007 Standard and arsenic-free residue is consistent with GB18598-2001 Standard, which can be bury safely. The extracted arsenic is transferred into copper arsensite for use as addictive in copper electrolysis and the waste water can be recycle after calcium is removed.

Jan 1, 2014

By Kevin Davey, Liza Forbes, Leanne Smith

Given the global scarcity and value of potable water, interest in the use of water of lower quality in mineral processing has grown significantly in recent years. Previous laboratory batch flotation tests conducted at CSIRO have shown that chalcopyrite floats strongly without collector in distilled water and that the collectorless flotability of chalcopyrite is unaffected by the use of brackish water, sea water or hypersaline water. In contrast, bornite is moderately flotable without collector in distilled water but all three lower-quality waters have a detrimental effect on the recovery of bornite. The depressant effect is so strong that the little recovery achieved in these waters was only slightly above what might have been expected from entrainment alone. This work has now been extended to another important copper sulfide mineral, chalcocite. In contrast to chalcopyrite and bornite, chalcocite does not exhibit collectorless flotability so the chalcocite tests in this study were performed in the presence of a standard collector (potassium ethyl xanthate). The results reveal that chalcocite is flotable with xanthate in distilled water but the lower-quality waters have a detrimental effect on the recovery of chalcocite. This effect is partly reversed by increase collector additions. Further tests were completed in order to investigate the effect of the different ions present in the saline waters on chalcocite flotation. Possible reasons for the observed differences are discussed in terms of the pulp chemistry of the system.

Jan 1, 2014