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Bio-Oxidation of Arsenic and Stibium Bearing Gold Ores Bio-oxidation of arsenic and stibium bearing gold ores with acidithiobacillus ferrooxidans was studied. The preoxidation results show that the best bio-oxidation technical parameters are the initial pH in the range of 1.8 ~ 2.0, particle sizes under 0.074 mm, temperature in the range of 25¦C ~ 30¦C and rotating speed of the orbital incubator in 100 rpm ~ 160 rpm. The leaching results show that If the ore, of which contain 10.37 per cent arsenic and 36.81 per cent stibium, is not bio-oxidised, gold leaching is only about 41 per cent, after 8 days oxidised, the result is about 76.55 per cent, which improved about 35.62 points. The relationship between gold leaching and arsenic oxidation is direct proportion, furthermore, it needs only partly oxidise and higher gold leaching could be get, for example, gold leaching is over 90 per cent when asenic oxidation is 60 per cent. The results will provide theoretical and technological supports of bio-oxidation arsenopyrite for pretreating refractory gold ores.

Sep 13, 2010

Study on Iron Ore Sintering with High Proportion of Specularite Concentrates Specularite iron ores have poor hydrophilicity and ballability as well as bad high-temperature reactivity, which restricts the large-scale application in the sinter and pellet production. In order to make the best use of the specularite concentrates, a novel process of Composite Agglomeration Process (CAP) is applied in this research. By the CAP, the percentage of specularite concentrates in the sinter mixture is increased to no less than 40 per cent as well as the coke breeze dosage is reduced by 0.3 per cent~0.6 per cent. Moreover, all the sintering indexes are obviously improved compared with the traditional sintering process. Researches on the metallurgical performances shows the finished composite agglomerates are high-quality burdens for blast furnaces. This investigation can provide an effective route to utilize the inferior specularite concentrates in the sintering.

Sep 13, 2010

Comparing Energy Efficiency of Multi-Pass High Pressure Grinding Roll (HPGR) Circuits With increased emphasis on reducing costs and carbon emissions in mineral processing, it is becoming essential to employ the most efficient comminution devices and to use them to maximum effect. High pressure grinding rolls (HPGR) are considered highly efficient compared with other devices, however their relative efficiency in multi-HPGR circuits is less well understood. A series of comminution tests was carried out to evaluate three multi-pass HPGR circuits and a jaw crusher-ball mill circuit. Combinations of HPGR units (1.0 m and 0.25 m diameter), jaw crushers and Bond ball mills were used to grind a 32 mm top size porphyry copper feed (BBWI = 12.1) to a product P80 size of about 150 ¦m. Up to three passes of HPGR were used in each circuit, with energy measurement and size analysis at each point in the comminution process. The energy efficiencies of individual comminution stages and of the overall circuits were quantified and evaluated using three different approaches. The operating work index method for comparing comminution energy efficiency underestimated HPGR performance due to the large amount of fines generated. The -75 ¦m efficiency factor and F50/P50 reduction ratio interpolation methods both give a fairer measure because they better take into account the amount of fines generated by HPGR. The results show that the relative comminution efficiencies of the three multi-pass HPGR circuits tested differ by as much as 22%, providing insights as how to best employ HPGR in a comminution circuit. The most energy efficient of the circuits tested was a three-pass HPGR circuit with a 1.0 m diameter roll on the first pass in closed circuit with an 8 mm screen followed by a second and third pass in a 0.25 m roll.

Sep 13, 2010

Plant-Based Trials of Monitoring of Coal Flotation Systems Using Electrical Impedance Spectrum Technique

Sep 13, 2010

Geological Parameters Controlling the Improvement of Manufactured Sand Using Vertical Shaft Impact Crushers Instead of Cone Crushers Natural sand is a limited resource. In Sweden the total use of natural sand and gravel is around 20 million tonnes per year and the goal is to halve the use of this resource in the near future. Most of this natural sand is used for concrete production, so the consequence of this goal is that more and more concrete must be produced with manufactured sand. The bedrock of Sweden consists mainly of granites and gneisses, rock types mainly composed of various amounts of quartz, feldspar and mica. Manufactured sand from these materials generally contains rather flaky and elongated grains, and there are few types of granite that can be used as manufactured sand in concrete without increasing the amount of cement by eight to ten per cent. A Vertical Shaft Impact crusher (VSI) is commonly used to improve the shape of coarse aggregate particles. Research has shown that it is even possible to improve the shape in aggregate fractions less than 1 mm for some rock types. The aim of this project was to investigate which geological parameters control the improvement of manufactured sand when using VSI-crushers instead of the traditionally used cone crusher. In order to do this eight rock types of granitic composition were investigated. The selection of rock materials for the tests was based on grain size and mica content. A 4 - 8 mm fraction of each material was used for the tests. The characterisation of the shape of the material was performed using image analysis applied on microscopic images. The results showed that the VSI-crusher had improved the shape of all materials down to 0.036 mm, except for one rock sample. According to these results granites with low mica content and relatively high content of feldspars have the best prerequisites to produce manufactured sand for concrete with suitable geometric characteristics, and if these materials are crushed with a VSI crusher they almost show the same characteristics as natural sand.

Sep 13, 2010

For establishing sustainable material cycle process in human system, a brand new concept should be created, which could recycle the waste materials, which are land-filled and discarded under present economical situation. The concept of 'RtoS' (Reserve (of waste) to Stock) to create 'artificial deposit' of the materials concentrate is one of the best ideas to be applied. From this viewpoint, separation technology, in especial, solid phase separation such as mineral processing technology contributes much to the concentration, making 'artificial deposit' with less energy consumption compared with melting and/or dissolving technologies. Results of rare metals concentration in the e-waste are also introduced as an example with combining novel comminution and parts/powder separation.

Sep 13, 2010

Chelopech Mining EAD and Best Available Techniques for Management of Waste Rock in Mining Activities

Sep 13, 2010

Sustainable development is a critical discussion topic in the mining industry today. The topic is necessarily broad and complex, covering an entire spectrum of related areas, from geology to end-use products. The objective of this keynote address is to focus on the chemicals and chemistry aspects - especially research and technology transfer - in sustainable mineral processing. Chemicals came to play a critical role in mineral processing during the last century, and they will play an equally vital role in confronting the sustainability challenges of the 21st century, particularly in the areas of greener chemicals, water efficiency and water resource management; waste reduction and remediation; minimising environmental impact, safety and health risks (meeting and exceeding the requirements of regulations); energy efficiency; and converting mineral resources into reserves. This keynote address argues that the current research framework is no longer adequate to serve the goals of sustainable mineral processing. The problems studied are often too narrowly defined or irrelevant, while the research efforts are fragmented and the methods and approach employed are often too reductionistic to produce useful knowledge. A new framework for research is needed. This address further argues that a new framework based on a holistic or systems approach can best tackle the challenges of sustainable mineral processing. Central tenets of this approach include a recognition that, in complex systems, the behaviour of the whole system is more than the sum of the individual contributions, and that interactions occur in real time, often in subtle and complex ways. The focus is thus on the behaviour of the whole system. Indeed, a comprehensive understanding of the system through large-scale measurements should precede a study of parts or of idealised models of the complex system. The result will be a sound knowledgebase, better solutions to the challenges of sustainable development, and improved technology transfer. Developing such a framework will pose a formidable challenge, requiring significant time and effort as well as a confluence of diverse specialties and strategic collaboration. Fortunately, recent developments in the context of reagent optimisation provide us with a prototype of a holistic approach. We can also draw upon methodological innovations in the biological sciences, where the critical need for a systems approach is well recognised and significant advances have been made.

Sep 13, 2010

Beneficiation of Iron Ore - Washing with Surface-Active Agent The stability of the dispersed phase in 10 wt per cent slurry of iron ore slime and fines was studied at pH 5 and different concentrations of surface-active agents. The behaviour of the dispersed phase of iron ore slime and fines is different for different surface-active agents. The improvement of iron value of slime and fines in the presence of surface-active agent is best realized at pH 8, where the Al2O3/Fe and Al2O3/SiO2 ratios in the concentrates are appreciably reduced. The polar functional group like -COO- interacts with hematite surfaces and forms outer- and inner-sphere surface complexes depending on the suspension pH and adsorbate.

Sep 13, 2010

Development of Technology for Complex Uranium Ores Processing on the Flotation Process Basis

Sep 13, 2010

The Effect of Mineral Liberation on the Floatabilities of Pyrite, Arsenopyrite and Arsenian Pyrite for Carlin Trend Ores

Sep 13, 2010

On the Kinetics and Equilibrium Models for Biosorption of Ni(II) onto a Gram-Positive Bacteria Strain, Rhodococcus opacus, for Environmental Applications The aim of this fundamental study was to evaluate the biosorption of Ni(II) from aqueous solution streams onto a Rhodococcus opacus strain through kinetics and equilibrium isotherms studies. The biosorption of nickel achieved its highest value in a pH around 5. The experimental data evaluation was carried out focusing three two-parameter models, as: Langmuir, Freundlich, Dubinin - Radushkevich. In order to determine the best isotherm fit, three error analysis methods were used to assess the data: correlation coefficient (R2), residual root mean square error (RMSE) and Chi-square test. The error analysis established that the Freundlich model fits better the nickel biosorption data. Maximum uptake capacity of nickel reached a value around 7.63 mg.g-1 for R. opacus. The biosorption rate was fast and achieved a removal of around 79 per cent of Ni(II) in the first 5 minutes at room temperature (25 ¦ 2¦C). The experimental kinetics data was evaluated considering two models (pseudo-second order and pseudo-first order). The error analysis established that the pseudo-second order model better fits the data.

Sep 13, 2010

Agglomeration for Copper Heap Leaching Agglomeration of ore is a method which can be used to eliminate the migration of fine grained particles throughout a leach heap. Without agglomeration, fine ore particles are able to migration within the heap, clogging flow channels and producing large areas where access of the solution is poor. In order to gain the benefits of agglomeration and improve agglomerate strength even further in copper heap leaching, an economical, acid-resistant binder is needed. However, most binders have been used without any systematic reasoning. A set of novel testing methods were developed, including a soak test, percolation flooded columns, and larger long-term leach columns. The soak test compares the degree of breakdown when agglomerates are subjected to an acidic environment. While the percolation flooded columns and larger long-term leach columns evaluate the flow of leach solution throughout the ore bed. Systematic studies have been completed on a wide range of binders using these novel testing procedures. It was found that for a low grade chalcocite ore, which was rich in silica, from a southwest US mine, polyacrylamides reduced the fines migration the best in the novel soak test. The non-ionic binder, in particular, was found to reduce fines migration as much as 93 per cent. Several of the binders tested were shown to increase the hydraulic conductivities of the agglomerated ore up to 2.5 mm/sec, compared to a hydraulic conductivity of only 0.25 mm/sec when no binder was used. These binders also prevented 'slumping' of the ore, which indicates a decrease in breakdown of the agglomerates. The use of a binder also showed no interference with leaching reactions in long-term leaching experiments.

Sep 13, 2010

Reduction of Iron Content from Silica by Gravitational Processes In this research work, it was attempted to reduce the iron contents (Fe2O3) in silica sample which was provided from Shenin silica mine using gravitational processes including jig machine, multi gravity separator (MGS), shaking table and spiral. The silica sample contains 93.75 per cent SiO2, 0.44 per cent Fe2O3, 2.78 per cent Al2O3, and 0.08 per cent TiO2 and the Fe2O3 has to be reduced to about 0.1 per cent or less than 0.02 per cent. Mineralogical studies and XRD analysis indicated the presence of haematite, pyrite and goethite as the major iron impurity phases. Mineralogical studies of polished and thin sections yielded that the degree of freedom of silica is more than 80 per cent in the range of -300 +212 mm. After elimination of fine particles, at first nine tests were carried out on crusher product (in two size fractions), wet rod mil product and scrubber product by means of Jig Machine. The best results were obtained with about 0.15 per cent Fe2O3 on rod mill and scrubber product which was not desirable. Thereafter 7 tests were carried out using shaking table; the best results were obtained with about 0.14 per cent Fe2O3 on rod mill and scrubber product which was not desirable. MGS showed the worst result in order to iron removal from silica which was not desirable. Finally 9 testes were carried out using spiral whish is the best gravitational separator for elimination of iron impurities from silica. The best result of spiral tests were achieved on scrubber product. In this test concentrate weight percent and its Fe2O3 grade were 82.32 per cent and 0.085 per cent respectively. Finally a test was carried out using 2 stages of spiral in order to develop flow sheet. In this test concentrate weight percent and its Fe2O3 grade were 78.8 per cent and 0.1 per cent respectively. This product can be used to produce float (clear flat) glass.

Sep 13, 2010

Thermodynamics of Non-Cyanide Gold Solvents The present status of the raw material base in the gold industry requires specific ways to recover gold and silver from ores. Most gold is closely associated with sulfides which require flotation followed by pressure or bacterial oxidation. The next stages of processing usually require using expensive operations for the preparation of leaching. A lot of researchers want to find a new alternative solvent for the extraction of precious metals from these products. According to the authors, one of the best ways is to use sulfur-based solvents (thiosulfate, sulfite, and their various mixtures). Thermodynamics of gold and silver thiosulfate dilution are calculated for conditions: the concentration of Au - 200 mg/L, oxygen - 3.2 mg/L, thiosulfate - 79 mg/L, OH- - 170 mg/L. the general result is the possibility of process remains under standard conditions. (erAu = = 0.035 V, ?G298 = - 29.18 kJ/g-atom ??). Silver with thiosulfate forms two strong complexes: [AgS203]- and [Ag(S203)2]3-. ?G0 = -1027 kJ/mol. The complex [AgS203]- is less stable: ?G0 = 486 kJ/mol. It should be noted that despite the high stability of gold complexes, the sodium thiosulfate may decompose to sulfite and elemental sulfur during the process, especially when heating. Gold is slightly soluble in the sodium sulfite solution, however it forms the strong complex [Au(SO3)2]3-. Depending on the concentration of free S2O32-ions, silver with sodium sulfite forms three complexes: [AgSO3]-, [Ag(SO3)2]3- and [Ag(SO3)3]5-. The dissolution speed of gold in sodium sulfite solution may be in the same range as it is during cyanidation. In this case, a practical application of sulfite process can be also used, especially for the products containing free elemental sulfur. In conclusion, sulfite-thiosulfate gold lixiviants can be used for concentrates after pressure oxidation of the cakes.

Sep 13, 2010

Upgrading of MgO in Dolomite Ore by Froth Flotation

Sep 13, 2010

Stripping of Fe (III) from D2EHPA Using Different Reagents The common way to extract Fe(III) from an organic solvent is by using concentrated acidic solutions. The stripping of Fe(III) from organic solvent Di-2-ethylhexyl phosphoric acid (D2EHPA) by hydrochloric acid (HCl) solutions has been found to increase with increasing the acid concentration. However, the use of a concentrated acidic solution such as 6 M HCl can degrade the organic molecules. In this research, to increase the efficiency of Fe(III) stripping from D2EHPA, effect of some acids, salts and buffer solutions was studied. Influence of Tri-butyl phosphate (TBP) as modifier on the Fe(III) stripping operation was also investigated. According to the results, the best Fe stripping recovery was achieved in the presence of low acid concentration and the salts which was 72.4 per cent oxalic acid, 70 per cent ammonium oxalate and 75 per cent buffer of oxalic acid and ammonium oxalate. The results also showed a better recovery in the presence of the buffer rather than the salt. Finally, increasing the concentration of TBP, HCl and H2SO4 resulted in a higher stripping efficiency of Fe(III). However, in the presence of oxalic acid and its salts increasing the reagent concentration did not increase the stripping efficiency and at this condition, the recovery of iron remained constant.

Sep 13, 2010

Techniques Used and Problems Encountered in Normal and Reverse Circulation Drilling at the Mt Roseby Project, Cloncurry, North West Queensland

Sep 13, 2010

The Operation of the LAROX PF-50 Pressure Filter at 'Ellatzite-Med' Flotation Plant, Bulgaria The implementation of Larox pressure belt filter, type Larox PF-50 provided within 6˜8% moisture content of the produced copper concentrate, which allowed good market realisation. The start-up of the pressure filter in 2009 reduced the electricity costs several times and had a positive impact on the technological regime of flotation. This article reveals the investigation results from the operation of the pressure filter according to different situations (density of the pulp, time for filtration, pressure of the material, pressure of the drying air, time for drying with air and other factors). The investment made in the pressure filter application is a guarantee for the successful operation of 'Ellatzite' flotation plant, Bulgaria in the coming years.

Sep 13, 2010

Optimisation of the Advanced Automation System at Inmet Mining's PyhSsalmi Mine, Finland

Sep 13, 2010