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By Valentine Chanturiya1

We have developed a classification of geochemical barriers according to their origin, i.e. natural and artificial, and according to methods and areas of application. There has been an examination of the interaction between different classes of geochemical barriers with sulfate solutions containing nickel, copper and iron. As natural barriers, carbonates (calcite and dolomites) were used. For artificial barriers, a mixture of serpentine and carbonatite, thermo-activated copper-nickel dressing tailings, and a magnesium-containing sorbent based on brucite was used. Keywords: geochemical barriers, physical-chemical geotechnologies, treatment of natural and waste water, recovery of nonferrous metals

Sep 1, 2012

By Leopoldo Gutierrez, Esau Arinaitwe, Marek Pawlik

"The effect of various polymers, including: anionic carboxymethyl cellulose (CMC), polystyrene sulfonate (PSS), humic acids (HA) and non-ionic hydroxypropyl cellulose, on the wettability of Athabasca bitumen was evaluated through dynamic contact angle measurements using the captive bubble technique. The tests were carried out as a function of pH at a constant ionic strength (0.01 mol/L sodium chloride). The evolution of the three-phase contact angle between the solution, bitumen and an air bubble was followed as a function of time over a period of ~6 minutes. The contact angle data were modelled using a first-order kinetic equation. The results were analyzed in terms of the initial contact angle, the evolution rate constant, and the steady-state contact angle value. In the case of anionic polymers, a pronounced decrease in the initial contact angle value was observed at pH 3. Under acidic conditions, there was no significant effect of CMC observed on the steady-state contact angle value but PSS and HA significantly decreased the steady-state contact angle value. At pH 8.5. the anionic polymers did not affect the wettability of the bitumen surface but they significantly decreased the contact angle evolution rate. These results suggested that CMC is not capable of permanently lowering the hydrophobicity of bitumen, and the polymer only slowed down the evolution of the contact angle to the steady-state value. The results also showed that polystyrene sulfonate and humic acids were capable of making bitumen hydrophilic but only under acidic conditions. Only hydroxypropyl cellulose (HPC) produced a large decrease in the steady-state contact angle under alkaline conditions (pH 8.5). The kinetics of contact angle evolution in the presence of HPC was also drastically lowered. The results were discussed in terms of the chemical composition of the polymers and their different affinities towards the bitumen surface."

Jan 1, 2014

By John A. Herbst, Ming Song, Xiangjun Qiu

"It has been known for sometime that as wear occurs in tumbling mills there is an associated change in mill throughput. These changes have traditionally been simplistically, attributed to “mill volume effects”. New high fidelity simulation (HFS) tools (involving DEM, CFD and Breakage models) are now giving new “microscale” insights into the complex interactions that occur between evolving lifter/liner profiles and breakage. An illustration of this analysis is shown in Figure 1 below.Here we see that after a new lining is installed (Region I) the wearing process reduces the liner thickness resulting in a larger power draw and an associated higher throughput until Region II is reached. By this point the lifter height is reduced significantly changing charge motion (less cataracting) the power begins to decline, but the comminution efficiency increases with this type of “calmer” breakage environment therefore the throughput continues to increase. In Region III the lifter is no longer providing the minimum required charge lifting action, the power and the throughput both drop off significantly. In the last two stages the behavior is especially complex because throughput is not linearly related to power since grinding efficiency is changing.The study described here shows that these new HFS tools allow the design of wear part profiles which will maximize mill productivity over the entire life of liner/lifter systems. A simple example of such a design procedure is shown involving the selection of a sinusoidal profile for a 34 ft diameter SAG mill.The paper discusses how the principles exposed in this simple example can be applied to search for an optimal profile in which non-standard modifications are allowed to compensate for throughput or wear shortcomings of standard profiles."

Jan 1, 2003

By Muammer Kaya, Sait Kursunoglu

"Energy is the major concern for society. It is expected that developing country economies and populations will grow and consume more energy. Interest in nuclear power is rising, while the world looks for non-depletable energy source that will not contribute to global warming. However, it still has concerns of nuclear proliferation, radioactive waste and safety. It is necessary to overcome these concerns if nuclear energy is expanded to developing countries. Thorium (Th) utilization as nuclear fuel will be an opening key of these difficulties because Th produces less Plutonium (Pu) and less radioactive waste with enhanced safety. Research into the use of Th as a nuclear fuel has been taking place over forty years, through with much less intensity than that for uranium (U) or U-Pu fuels. Nuclear industry is currently using only 0.7% of the available energy from mined U. With huge resources of Th and relatively little U, Turkey has made utilization of Th for large-scale energy production a major goal in its nuclear power programme. Thorium fuel is plentiful and inexpensive. Energy is major concern for developing Turkish society. Turkey, today exports more than 70% of its energy as fossil fuels. In the last 50 years, Turks are skeptical, anxious and indecisive about having nuclear energy for electricity production. In the last 10 years, Thorium is brought into Turkish government’s attention and national discussion as a new, safe, clean, affordable, CO2-free, alternative, strategic and domestic nuclear energy fuel. Turkey recently contacted four VVER-1200 type Russian Nuclear Power Reactors using U as a fuel in Akkuyu (Rosatom) and another four units will be established in Sinop in the next decade by Japan (Mitsubishi-Westinghouse). Turkish nuclear programme must envisage use of domestic Th as a fertile material. This paper briefly reviews the developments of Th-fuel cycle for nuclear energy from global and Turkish perspectives. Previous Th reserve development and recovery studies from Turkish bastnasite ore are summarized in this paper."

Jan 1, 2014

By Yimin Zhu, Dezhou Wei, Haijun Liang, Zhifu Zhou

Pyrite is one of sulfide minerals most widely distributed in the earth. During the flotating separation of metal sulfide and the floating desulfation of coal, it is often requaired to restrain pyrite. However, the result is not very satisfactory because of the little difference of floatability of minerals to be separated. The problem is extremely outstanding for the floating desulfation of coal. Researchers carried out a number of experiments with T. ferrooxidans (Yang et al, 2001; Zhou et al, 2000; Zhou et al, 2001; Wei et al, 2001) for an enhanced restraint to pyrite. The results showed that the T. ferrooxidans after being cultured works the best in restraining pyrite. After 10 min pretreatment, the removal rate of pyrite from coal is up to 80%~90%. The research results by Yuan Xin et al (Yuan et al, 2000) show that T. ferrooxidans can restrain effectively the floatability of pyrite and can reduce the recovery of pyrite from 95% to 8%. Though the restraining properties of T. ferrooxidans to pyrite have been proved by many tests and experiments, there are very limited reports on its restraining mechanism. Thus, a systematic experimental research is carried out in this paper.

Jan 1, 2003

By Boris Albijanic, Hongjuan Chen, Bogale Tadesse

"During mechanical flotation of fine liberation sized complex rare earth ores, a large fraction of ultrafine valuable mineral particles are lost to tailings. Fine gangue mineral particles can be entrapped within the froth phase and be floated together with target mineral particles. Another common challenge in ultrafine rare earth mineral flotation is the formation of a sticky froth (excessively stable froth). Thus, the improvement of the flotation of fine and ultrafine rare earth bearing minerals through appropriate cell design and reagent selection is highly desirable. The aim of this study is to investigate the performance of a pico-bubble cavitation flotation column in improving selective recovery of ultrafine rare-earth elements (REEs) bearing minerals from complex and low-grade ores. In pico-bubble cavitation column, very small bubbles are generated which are capable of attaching to ultrafine particles and consequently modifying their surface properties. The overall effect of these processes should lead to improved flotation selectivity and recovery of ultrafine RE mineral particles. In this paper, the effects of a number of flotation operating variables on recovery and grade of REE minerals was investigated using a continuous pilot scale pico-bubble column flotation. At the flotation conditions used in this study, subtle monazite upgrade was observed while gangue Fe oxide was preferentially floated even in the presence of depressants. INTRODUCTION Rare earth elements (REEs) have unique properties such as superconductivity and catalytic activity, and are in high demand for a large number of cutting-edge technologies in the modern world including the production of mobile phones, fuel cells, displays, permanent magnets for wind power generation, high-capacity batteries, green energy devices, etc (Naumov, 2008). REEs tend to be intimately associated within many minerals, and are rarely found in high concentrations in deposits for economic extraction. Up to now, among over 250 minerals containing REEs, bastnasite (Ce), monazite (Ce, Th and La) and xenotime (Y) are the three main minerals that contain sufficient grade of REEs for commercial exploitation (Zhang and Edwards, 2012). The deposits that contain bastnäsite, monazite and xenotime usually have complicated mineral compositions, with various valuable minerals of fine embedded grain sizes in association with complex gangue minerals. In order to ensure liberation of the REEs minerals, fine grinding to less than 30 µm is necessary. This fine grinding leads to difficulty in recovering a large proportion of fine and ultrafine particles in separation processes such as flotation (Trahar and Warren, 1976). Consequently, highly liberated and ultrafine fine valuable REEs particles are lost into tailings during traditional mechanical flotation. Besides, the formation of extremely sticky and stable froth inhibits the drainage of hydrophobic particles. Thus, improving flotation of rare earth bearing minerals, particularly the ultrafine size range, is highly desirable."

Jan 1, 2018

By Z. T. Yuan, S. L. Qi, Q. Y. Meng, G. X. Zou, L. X. Li, J. W. Lu

"The selective separation of pentlandite from serpentine was investigated using the magnetic coating-magnetic separation by conditioning slurry pH value, stirring speed, magnetic field intensity and controlling dosages of sodium hexametaphosphate (SHMP) and sodium oleate (SO). The optimal conditions were obtained as follows: the natural pH of 6.8-7.2, stirring speed of 2300 rpm, magnetic field intensity of 200 kA m-1, SHMP of 60 mg L-1, and SO of 400 mg L-1. Results showed that the Ni grade was 21.4% with the Ni recovery of 81.4% and MgO content of 3.8%. FTIR indicated that coagulant of SO preferentially adsorbed onto pentlandite and magnetite particles while hardly adsorbing onto serpentine particles when dispersant of SHMP was used. Thus, the selective magnetic coating of magnetite on pentlandite surfaces could be formed due to the formation of hydrophobic surfaces on pentlandite and magnetite particles. Calculations of DLVO (Derjaguin-Landau-Verwey-Overbeek) confirmed that interactions between magnetite and pentlandite particles were much stronger than that between magnetite and serpentine due to the existence of hydrophobic interactions with the addition of SO. Consequently, the pentlandite was successfully separated from serpentine. Therefore, this study exhibits the potential to separate pentlandite from serpentine minerals for practical applications and thus deserves further study.INTRODUCTION It has been well known that the separation of pentlandite from serpentine is a worldwide challenging issue in the processing of sulphide nickel-copper ores. Because the serpentine mainly causes the high pulp viscosity and slime coating on the pentlandite, which interferes with the flotation process of pentlandite (Cao et al., 2016; Feng et al., 2012). The fibrous mineral of serpentine preferentially attaches to the air bubble, forming bubble-macrofibers aggregates, which are easily floated into the nickel concentrates, resulting in the decline of Ni grade (Alvarez-Silva et al., 2016; Kusuma et al., 2014). In addition, the serpentine adheres to the pentlandite as hetero-aggregation or slime coating via the electrical interaction between a positively charged serpentine and a negatively charged pentlandite, which decreases the hydrophobicity of pentlandite and reduces the collector adsorption (Feng et al., 2013). In other words, the presence of serpentine or the occurrence of aggregates (including slime coating and bubble-macrofibers aggregates) seriously affects the flotation process and deteriorates the flotation of pentlandite. Therefore, we propose magnetic separation to recover pentlandite from serpentine with the magnetic coating technology, which is different from forth flotation."

Jan 1, 2018

By Arkady Senchenko

The paper deals with the problem of refractory gold-containing material processing. It is observed that all traditional methods for liberation of fine gold from this type of products are characterized by a number of essential disadvantages, where the main ones are ? considerable expenses for ore processing and big environmental impact. As an alternative to the existing methods there is considered a gold liberation method, which is based on the combination of ultra fine grinding process with the consequent atmospheric oxidation. The theoretical justification of atmospheric oxidation was carried out, in the result of this the mechanism and the degree of sulphide minerals? oxidation was found out, the dependence of gold dissolution speed on the slurry content in liquid phase produced by grinding and oxidation was identified. The experimental data and results of pilot-plant testing are given and the most effective grinding and atmospheric oxidation mode is selected on this basis. The performed complex of research works allowed us to use the provided technology at the gold processing plant having capacity of 8 mln. tons of ore per year. The questions, problems, advantages and disadvantages of atmospheric oxidation technology for refractory gold-containing concentrates are considered in this paper. Keywords: refractory gold-containing material processing, gold liberation method, cyanidation

Sep 1, 2012

By Sergey Gudkov, Yuri Yemelianov, Stanislav Balikov, Andrey Boldyrev, Andrey Bogorodsky

"The results of POX of refractory gold-bearing concentrates using halide-ion as a lixiviant for precious metals and activated carbon as an adsorbent are given. It was found that gold did not recover to the solution when halide was added during POX. Silver partially dissolved in the solution. When halide-based reagents and activated carbon were added during POX, gold dissolved and loaded onto the activated carbon. The degree of sulfides oxidation was 99.3-99.6%. The recovery of gold onto granulated carbon was 94.7-94.8% when using chlorine-bearing lixiviants: NaCL, CaCL and carnalite and 98-99% when using KJ and KBr. This treatment process of refractory gold-bearing concentrates combines sulfide oxidation, dissolution and adsorption of precious metals. The results of the metals recovery achieved using this process can be compared with the recovery during POX-cyanidation. In this case, sodium cyanide was not used. This allows the reduction of capital and operational costs due to the absence of cyanidation, CIL and detoxification of leaching tailings circuits."

Jan 1, 2014

By João Queiroz, Cristian Marquez-Sarmiento, Luiz Teixeira

The removal of various metals from process waters and effluents is usually done by precipitation of the corresponding hydroxide. Manganese however is one metal that does not respond efficiently to that approach. It may be seen in its eH X pH diagram that the way of oxidation to Mn IV rather than hydrolytic precipitation of the Mn II ion as its hydroxide, is the way to efficient precipitation of Mn in the pH range 6 to 10. We studied the use of oxidants O2; NaClO; H2O2; Caro´s Acid (H2SO5) and the combinations of O2 or H2O2 with Na2S2O5, and H2O2 with NaClO, for the oxidative precipitation of Mn from synthetic solutions starting with 10 mg/L Mn, at 25 oC. In adequate conditions, which include pH > 8, it is possible to reach final [Mn] less than 0.1 mg/L in 60 minutes of reaction time.

Jan 1, 2014

By Majid Saghaeian, Rasool Hejazi, Parisa Ghobadi

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

Jan 1, 2014

By J-P Franzidis, P. O. Gyebi

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

Jan 1, 2018

By M. Paymardi, A. Foroutan, T. P. Oladele, M. Abbaszadeh

"Reducing the amount of zinc and iron in lead concentrate is one of the important aspects of processing in lead and zinc flotation plants which results in improvement of lead concentrate quality and prevents zinc loss. In mineral flotation industries, lignin sulfonates are known for their depressant properties for both non-metallic and sulfide minerals such as pyrite and pyrrhotite.This paper investigates the effect of lignin sulfonate on flotation of galena, sphalerite and pyrite in sulfidic lead and zinc bearing ores. Batch flotation tests were carried out on a high pre-activated zinc samples. The feed contains 0.9% lead, 2.3% zinc and 7.5% iron. The dosage of all reagents such as sodium cyanide, zinc sulfate, ethyl xanthate and methyl isobutyl carbinol (MIBC) were kept constant for lead flotation step except calcium lignin sulfonate (CLS) that was varied between 0 and 80 gr/ton.Results for lead rougher concentrate showed that the grade of lead increased by 2.7% while the recovery decreased around 4 % at the highest dosage of CLS. Furthermore, zinc recovery decreased by 6.3% with no significant change in grade. Iron recovery in lead rougher concentrate decreased by 2.3 % while the grade changed around 1%. In sphalerite flotation step, CLS dosage was changed in the range of 0 to 80 gr/ton while the dosage of other reagents such as copper sulfate, lime, amil xanthate and MIBC were kept constant. In this step, no decreasing in grade and recovery of zinc was observed, while iron recovery decreased. It was suggested that CLS has a depression effect on sphalerite in conjunction with other zinc depressants such as zinc sulfate and sodium cyanide. CLS was further used in plant with non-pre-activated zinc minerals. Similar trends were observed in plant.INTRODUCTIONlead-zinc sulfide minerals play an important role in the production of lead and zinc metals in the mineral processing industry (Luo, Feng et al. 2016). Due to complexity of the lead-zinc ores mineralogy, in some situations, their flotation properties vary significantly from one deposit to another one even in itself (Bulatovic 2007)."

Jan 1, 2018

By I. Nishkov, I. Grigorova, M. Ranchev, S. Dzhamyarov

"Chelopech concentrator (part of Dundee Precious Metals) is located in central-western Bulgaria. The current process plant utilizes conventional primary crushing and SAG mill grinding, copper and pyrite rougher and cleaner flotation stages to produce a marketable gold-rich copper and pyrite concentrates. As in the most processing plants, the pyrite depression is carried out alkaline media using lime. The subsequent activation of pyrite mineral is achieved by adding sulfuric acid, which has an adverse effect on the flotation equipment. Therefore, a series of laboratory flotation experiment for activation of lime depressed pyrite by ammonium salts, such as ammonium chloride (NH4Cl), ammonium sulfate (NH4)2SO4 and ammonium bicarbonate (NH4HCO3), have been conducted. The obtained results showed that ammonium bicarbonate proved to be the most appropriate reagent choice for pyrite mineral activation. These results are confirmed by X-ray photoelectron spectroscopy (XPS), performed to determine the surface chemistry of pyrite in its natural state, after lime treatment and subsequent treatment by NH4HCO3. The registered XPS spectra indicate that the hydrophilic phases on the pyrite surface could be efficiently removed by using the ammonium salt NH4HCO3. The industrial use of NH4HCO3 as an activator of lime-depressed pyrite is a possible alternative for sulfuric acid replacement as a most widely used pyrite activator. Flotation experiments with addition of 200, 400, 600 and 800 g/t from each of the studied ammonium salts have been conducted. Furthermore, the impact of the flotation pulp pH within the scope of 9.00 – 10.50 was also investigated. The obtained results from the laboratory flotation experiments, showed that the pyrite activation with ammonium bicarbonate is an excellent possibility for replacing the sulfuric acid as main pyrite activator reagent, in order to eliminate the gypsum accumulation during the flotation of pyrite in Chelopech concentrator.INTRODUCTION The Chelopech deposit, located about 60 km east of Sofia is one of the largest Cu-Au deposits in Europe. The ore have complicated mineralogical and chemical composition. The main ore minerals are represented by pyrite, enargite (luzonite), tennantite, chalcopyrite and bornite. The average copper content of the mined ore is about 1.1 % and the gold content is about 4.0 g/t."

Jan 1, 2018

By M. I. Panayotova

Some of effluents released by copper smelting plants are highly acidic (pH = 0~1) and contain arsenic and copper in relatively high concentrations (10~20 g/L). Usually arsenic is removed by precipitation with different reagents, such as lime, iron salts, calcium salts, aluminium salts, etc. Precipitates (often voluminous) that require further handling are formed and copper and other valuable components are lost. A method is presented for copper and arsenic extraction from acidic effluents. Effluents are treated in specially designed closed electrochemical cell without chemicals? addition. Gases formed are collected and treated for decomposing the eventual traces of As-bearing compounds and ensuring the environment protection. Initially copper of grade of 85 % is electro-won. Further about half of the initially available arsenic is separated as low-soluble, low volume mixture of intermetallic compounds, oxides and some elemental arsenic. At the next stage the main part of the left arsenic is immobilized as low soluble stable compound. Arsenic content in the treated acid is in the range 0.20~0.25 g/L. Acidity of treated effluent after first two stages remains practically unchanged and the solution can be re-used. Physicochemical and electrochemical processes, governing copper and arsenic removal, are discussed.

Jan 1, 2014

By J. K. Wen

The Mojiang nickel deposit is situated in Mojiang county, yunnan province, a tropical area in the southwestern China. The known geological resource (measured and inferred) includes 4 million tons of nickel sulphide ore at an average grade of 0.50% Ni and 0.34% As. Nickel minerals are mainly gersdorffite (NiAsS), millerite(NiS), morenosite (NiSO4?7H2O), and more than 50% nickel minerals is gersdorffite which contains arsenic. Pyrite is the dominant sulfide mineral, 22% in the ore and part of nickel minerals are locked in pyrite. It is difficult to attain the nickel concentrate quality allowed by a smelter and the acceptable nickel recovery through flotation due to the high arsenic in the ore and the nickel minerals locked in pyrite. The shake flask tests and column tests for nickel recovery from the Mojiang nickel sulfide ore had been finished by the end of 2003. The column bioleaching tests were carried out using the columns with diameter of 120 mm and height of 1200 mm, and 70% of nickel dissolution was attained in 300 days. A 10,000t pilot test heap was built in the Mojiang Nickel Mine by June 2003. The ore used in the test heap was supplied from the underground mine and was crushed to -20 mm before being feeding to the test heap, which is 4~5 m high, 30 m wide and 50 m long. The naturally adapted mesophile and moderate thermophile have been inoculated into the leaching pile by June 2003. The operating temperature in the heap ranges from 38? to 55?, varying with season. 30% of nickel dissolution was achieved in 3 months and the typical pregnant leach so-lution (PLS) contains 2~3 g/L Ni and 20~30 g/L Fe. The Ni sulfide which was produced by us-ing Na2S 10 t/t?Ni contains 16%~20% Ni and Ni recovery was 98%. 70% of Ni dissolution is expected in 12 months. The test heap was scaled up to 60,000 t of ore per year by mid of 2005. In this paper metallurgical studies and performance of the pilot test heap will be described. The results of mineralogy, shake flask tests and column tests on bioleaching of the nickel sulfide ore are reviewed. The key test heap operation parameters, the performance of bio-heap leahing-Na2S precipitation, ferrous oxidation-ferric precipitation-Na2CO3 precipitation, bacteria in the pile, water and acid balance, effluent disposal, capital and operation costs are also discussed.

Jan 1, 2014

By J. Seo, W. Kim, I. Bae

"Microcrystalline silica impurities such as quartz and opal-CT commonly associated in bentonite should be controlled and removed as far as possible when bentonite is used as biocompatible raw material because they show sufficient evidence of carcinogenicity. Since opal-CT contained in bentonite in trace amounts cannot be well separated by conventional sedimentation method, in this work, the ultrasound-assisted removal of the impurity was attempted. Irradiating ultrasound into bentonite-water suspension promoted the production of fine montmorillonite particles in the suspension and the production markedly increased when montmorillonite was activated by Na2CO3. Subsequent centrifugation of the suspension made it possible to recover pure montmorillonite particles as an overflow product. Only 16.2 mass % of total solids was recovered as an overflow from the non-activated suspension, whereas 63.5 mass % was recovered from the activated suspension at centrifuging speed of 10000 rpm. Increasing sonicating time enhanced the yield of overflow, however, excessive sonication up to 10 min hindered the purification of montmorillonite. It was observed that the peak reflection of (101) plane of opal-CT in overflow increased as sonicating time increased during prolonged sonication. INTRODUCTION Bentonite consisting predominantly of mineral montmorillonite is clay-rich soft rock generated frequently from the alteration of volcanic ash. Depending on the nature of its genesis, bentonite contains a variety of accessory minerals, which may include mainly quartz, feldspar, opal cristobalite/tridymite (opal-CT), calcite, illite and mica. The presence of these accessory minerals can impact the industrial value of the deposit, reducing its commercial value depending on its applications. Therefore, bentonite is often purified by removing these impurity minerals for special applications where specific properties and characteristics are required (Murray, 1999). Among the special applications, bentonite is often used in the cosmetic and pharmaceutical industry as both excipient and active ingredient in the forms of liquid (suspensions, emulsions), semi-solid (creams, ointments) and solid (powder, capsules and tablets). The basic requirements for bentonite to be used as raw material are pure, microbiological and mineralogical inertness. Physical properties such as swelling volume and gel formation are also important. Particularly, microcrystalline silica polymorphs such as quartz, cristobalite and opal-CT should be controlled and removed as far as possible because they show sufficient evidence of carcinogenicity in humans."

Jan 1, 2018

By V. Sovmen

The gold-ore Olympiada deposit is located within the Yenissei range (Krasnoyarsk Region, Russia). Primary sulphides ores are metasomatic changed rocks, mica-calcite-quartz structure with impurity amphiboles, chlorites, carbon, the rare thin grains of sulfides (up to 3%~5%) and native gold. The structures of ores are fine-grained, prevailing texture of ores - interspersed, vein-interspersed, band-interspersed, veinlet. The most important minerals in the deposit are: gold, arsenopyrite, pyrrhotite, antimonite, Sb-sulphosalt, quartz, muscovite, calcite, siderite, titanium minerals, chlorite and minor sulfides like chalcopyrite, galena, sphalerite, etc. A common problem in mineralogical studies applied to mineral processing (concentration, cyanidation, etc.) is the characterization of gold in ores and technological products. This paper discusses the behavior of minerals during technological process at operating factory in Olympiada Mine and gold distribution in the ores and products. For the mineralogical characterization of minerals ? combination of analytical techniques was used. Gold is encountered in the primary ores as free grains among rocks, growth with sulfides and nonmetallic minerals, inclusions in sulfides, sulphosalt, and nonmetallic minerals. The gold-sulphide ores of Olympiada deposit can be quite complicated for enrichment. With the purpose to increase the extraction of metal from concentrates by liberating the dispersed gold, forming inclusions in sul-fides, there is used technology of biooxidation of flotation concentrates in Olympiada Mine. Gold and the basic ore-forming minerals in the ores feed, sulphidic concentrates, biocakes, tailings of concentrates of flotation and products of hydrometallurgical leaching have been studied in the mineralogical research. During researches it is established that pyrrhotite was completely oxidized while arsenopyrite was oxidized almost completely in the bacterial oxidation process. Pyrite and antimony minerals behave similarly and were oxidized only partially. The main oxyhydroxides in the bacterial oxida-tion process are goethite, limonite and jarosite. The results of mineralogical researches showed reasons of losses of gold during hydrometallurgical enrichment.

Jan 1, 2014

By Jia Ma, Zhi-Chao Liu, Kang Liu, Chun-Feng Li, Bao-Bin Tang

"The geological environment of the certain uranium-molybdenum deposit is very complicated. While the study of process mineralogy is relatively few, which restricting the processing and leaching effect of ores. According to reaserch on process mineralogy of this mine, the basis of ore processing can be provided. The main contents of research are the uranium occurrence state and the influence of H2O2 in acid leaching. By various methods and experiments, the process of uranium mineralogical characteristics in this deposit are systematically studied. The results show that the uranium is mainly in the form of independent uranium minerals. The structures of these uranium minerals are venous and disseminated in mineral fissures, or microgranular inclusions in quartz and feldspar. It is not appropriate to concentrate the uranium minerals by flotation beneficiation because that the loss rate of target metals via water leaching process is very high. The ores are suitable for being acid leaching directly with 6% – 8% of H2O2, and the maximum leaching rate of uranium can be 96.88%. INTRODUCTION The uranium ores with associated elements have a large proportion in uranium resources (Lei, et al., 2014, Xing, et al., 2006; Ritchy and Wong, 1985). The uranium and molybdenum are easy to be paragenesis in nature enviroment because of their similar chemical properties. Therefor the uranium-molybdenum associated deposits are widely existing, such as the sedimentary sandstone uranium deposit in American with vanadium and molybdenum, the sedimentary sandstone uranium deposits in French with vanadium (Chen, et al., 2014; Lounis, 1997). A certain epithermal porphyry uranium-molybdenum deposit in China is mainly controlled by the subrhyolite- porphyry and the fault zone (Lv, 2012; Rui, 2010; Liu, et al., 2010). The ore properties of this deposit are complex, which include the high alteration degree, and the fine grain size of the target minerals (Ma, et al., 2013). The ore properties and occurrence state are quite different during each mining stage. As a consequence, the consumption of reagent increased and the leaching rate declined as long as the continuously mining. The author explored the best leaching rate of target elements According to the basic research on process mineralogy of present ores, experimental study of water leaching and oxidizing acid leaching on different particle sizes."

Jan 1, 2018

By Jan Svoboda, Atsushi Shibayama, Toyohisa Fujita, Toshio Miyazaki, Kenji Murata

"The electrical disintegration (ED) method and disintegration by underwater explosion were investigated as new fragmentation techniques for the kimberlite ore and tungsten scrap of superalloy (carbide bit). The results of various breakage tests demonstrated that both fragmentation methods as new disintegration techniques for recycling were able to liberate various components of materials of different resistivity and elastic impedance.SUMMARYThe breakage of the kimberlite ore from South Africa (sample size: 15 mm x 15 mm x 6 mm) was achieved by the ED method. A relationship between the sample size, voltage, the electrical current and the energy needed for the disintegration was found from the experimental results. Kimberlite exhibited a high degree of breakage, when the high voltage of 60 kV and the pulse current of approximately 5000 A were applied to the sample by the generator during 0.2 microseconds (Fig. 1)."

Jan 1, 2003