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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 T. Tsurata

The accumulation of thorium and/or uranium by various microorganisms from a solution containing thorium and/or uranium at pH 3.5 was examined. Among the species tested, a high accumulation ability for thorium was exhibited by strains of gram-positive bacteria, such as Bacillus megaterium, B. subtilis, Micrococcus luteus, Rhodococcus erythropolis, and actinomycetes, such as Streptomyces levoris. On the other hand, though uranium was accumulated in small amounts from the solution containing both elements by all these microorganisms, actinomycetes, such as S. flavoviridis and S. levoris had relatively high uranium accumulation abilities. In these high performance thorium- and uranium- accumulating microorganisms, S.levoris, which accumulated the largest amount of uranium from the solution containing only uranium at pH 3.5, could accumulate about 300 µmol thorium and 133 µmol uranium per gram dry wt. of microbial cells from a solution containing both thorium and uranium at pH 3.5. After this screening, uranium accumulation using microorganisms isolated from uranium mines, among which some strains of bacteria were found to possess an extremely high uranium accumulating ability. The microbial biomass may thus be considered for use as an accumulating agent for the removal and recovery of uranium that may be present in metallurgical effluents, mine tailings, seawater and other sources. Recently, hundreds of micro-organisms existing in uranium deposits located in North America, Australia, and Japan for their ability to accumulate large amounts of uranium, and found some new strains which accumulated large amounts of uranium, such as Lactobacillus and Bacillus sp. from Japanese and Arthrobacter and Bacillus sp. from the United States uranium deposits. These bacterial strains can accumulate about 2500 µmol uranium per gram dry wt. of microbial cells within one hour. These microbial cells can remove uranium from the uranium refining wastewater with a high efficiency. The accumulation of uranium from a solution (pH 5.8) by microorganisms contained Arthrobacter nicotianee, which is a similar strain mentioned above Arthrobacter sp., was examined. Among the 76 strains of 69 species tested (23 bacteria, 20 actinomycetes, 18 fungi, and 15 yeasts), high uranium accumulation ability was exhibited by strains of the bacteria, A. nicotianae, B. subtilis, and M. luteus. A. nicotianae cells, which showed the best performance, could accumulate about 698 mg uranium (2.58 mmol) per gram dry wt. of microbial cells.

Jan 1, 2014

By J. Z. Yuan

The purity of rectorite is only about 70% after preliminary mineral processing, which has limited its application. In this research, different pulp densities, different dispersants, different dispersing methods and purification flow sheets were used to purify rectorite. The results show that it is possible to obtain high pure rectorite clay with the purity above 90% and concentrate yield between 24.9% and 29.4% by the purification process with composite dispersants, stirred mill grinding dispersion and so on. The obtained high pure rectorite can be further used in rectorite nanocomposites.

Jan 1, 2014

By D. Tao

A novel rotary triboelectrostatic separator has been developed and patented recently at the University of Kentucky with unique features, including a high efficiency rotary charger, charger electrification, laminar air flow, etc. A parametric study has been performed with a coal combustion fly ash sample to investigate the effects of major operating parameters on the process performance. Most significant operating variables and optimum conditions were identified. Separation tests performed with four fly ash samples indicated that the rotary triboelectrostatic separator showed effective fly ash separation.

Jan 1, 2014

By Morin D. H., Battaglia-Brunet F., D'Hugues P.

"In the mineral-processing field, bioleaching of metal sulphide concentrates is currently operated in very large mechanically agitated tanks. Such bioreactors have considerable requirements in terms of power consumption for mixing, aeration and heat transfer. The use of slurry bubble column, where the particles are suspended by gas motion as well as by liquid upward flow, could be an alternative to achieve bioleaching in more economical conditions. In order to compare these two techniques, a unit of stirred reactors in cascade and a bubble column were comparatively operated at laboratory scale in the bioleaching of a pyrite concentrate. For both pieces of equipment, experiments were performed not only in batch mode but also in continuous conditions.Bubble column performances were significantly affected by unpredictable technical difficulties met to maintain continuous feeding in the bubble column and by a significant settling of the heavy solid particles. Nonetheless, theoretical kinetic data, extrapolated from results in batch conditions, could be compared to those obtained in continuous tests, in bubble column and in mechanically agitated reactors. These kinetic data were used to evaluate the influence of reactor design and configuration choice on bioleaching performances."

Jan 1, 2003

By John Ralston, Jona Addai-Mensah, Patience Mpofu

The flocculation and dewatering behaviour of kaolinite (non swelling) and smectite (swelling) clay dispersions has been investigated using hydrolysable metal ions Mn(II) and Ca(II) and anionic polyacrylamide-acrylate copolymer (PAM) at pH 7.5 and 10.5. A pH-dependent, specific metal ion adsorption behaviour, accompanied by a marked reduction in particle zeta potential and slurry shear yield stress, was observed to have a profound influence on the colloid stability of both types of clays. Due to the differences in the cation exchange capacity, the smectite clay dispersion required a higher amount of metal ions than kaolinite dispersion to produce similar effects. The adsorption density of the anionic PAM at the negatively charged clay particle surfaces correlated well with metal ion hydrolysis and adsorption behaviour, all of which had a strong effect on slurry settling rate and extent of consolidation. At pH 7.5 where Mn(II) ions hydrolyse, metal ion and flocculant adsorption densities were both greater in the presence of Mn(II) than Ca(II) ions. At pH 10.5, however, where Ca(II) ions begins to hydrolyse, higher adsorption densities were observed for Ca(II) ions in comparison with Mn(II) ions, as the latter hydrolysed completely and precipitated. The metal ion mediated flocculant adsorption led to improved hydrogen bond driven particle bridging and facilitated charge neutralisation flocculation mechanisms which significantly enhanced the dewaterability of both clay dispersions.

Jan 1, 2003

By M. Karamoozian

Modelling and optimisation of the power draw of large SAG mills are important due to the large power draw which modern mills require (5~10 MW). The cost of grinding is the single biggest cost within the entire process of mineral processing. Traditionally, modelling of the mill power draw has been done using empirical models. Although these models are reliable, they cannot model mills and operating conditions, which are not within the model database boundaries. Also, due to their static nature, the impact of the changing conditions on the power draw, within the mill, cannot be deter-mined using such models. Despite advances in computing power, on-line modelling of large plant scale mills could be a time consuming task. On the other hand, using on-line parameters for model-ling, result in more reliable control of SAG mill without performing any more costly tests. In this paper, SAG mill power draw is modelled using neural network approach. Six inputs, namely: solid percent, two bearing pressures, noise, recycle and feed rate were used to model the power draw. The produced model shows an acceptable correlation coefficient, R2 =0.9623.

Jan 1, 2014

By Dominic Howarth, Diana Drinkwater, Don McKee

At a time when the mining and minerals industry across the world is undergoing unprecedented change, the very fabric of the tertiary education system which is the principal source of trained professionals to the industry is in decline in many countries. The change sweeping the industry is globalisation as evidenced by the emergence of a relatively small number of increasingly dominant corporations with operations in most of the major mining countries. The education sector is struggling to provide sufficient graduates as the viability of small mining schools declines. That is only part of the problem as the global operating industry is increasingly seeking graduates who are comfortable working in different countries and cultures. One obvious response to the industry needs and developments is for the education sector to consider how it can best respond to the global opportunities. This paper presents the case for a global education network which is based on a network of international thinking Universities and which makes use of the latest in educational thinking and technologies to provide a quality education and in the process produce graduates fitted for international careers.

Jan 1, 2003

By G. Rajesh

Mathematical modeling of bioremediation has gained importance as it is used as an optimization tool for the remediation process involved in contaminated sites. The bioremediation of Cr(VI) has been studied taking into consideration the initial Cr(VI) concentration Cr(VI)ini, bacterial growth substrate concentration (S), maximum growth rate (µmax), yield coefficient (Y), half saturation constant (Ks), and inhibition constant (KI). As the enzymatic reaction is also affected by initial substrate concentration (Sini) and Ks, different ratios of (Ks/Sini) are analyzed. As the inhibition constant (KI) is not constant for all the enzyme reactions and it varies with Cr(VI)ini, the correlation between (KI) and Cr(VI)ini is developed. A set of differential equations pertaining to bioremediation of Cr(VI) has been solved using FORTRAN 90 program adopting the model developed. The results are verified with the experimental data from the literature and a good correlation has been obtained between the experimental data and the model predictions. Keywords: bioremediation, hexavalent chromium, mathematical model, inhibition kinetics

Sep 1, 2012

By D. I. Verrelli

Within the flotation community a belief has developed that some particle shapes are more ?floatable? than others. This is usually attributed to an influence of particle shape or roughness on the induction period required to achieve attachment between the particles and the air bubbles in the pulp. Up to now, such measurements have not been able to readily isolate the effect on individual flotation subprocesses. In contrast, our experimental apparatus, the CSIRO Milli-Timer, enables us to directly observe the process of particle?bubble interaction and attachment by means of a high-speed video recording, thus providing a direct measure of the induction period for attachment. To assess the influence of particle shape on induction time we used two varieties of methylated borosilicate glass particles ? spheres and angular ?frit? ? in a range of tightly-sized fractions. In doing this, we take care to account for the influence of other factors that could affect the induction time, such as the polar angle of sliding commencement, and approach velocity. These parameters are recorded as variables for each interaction, and corrected for using multiple nonlinear regression. Our results illustrate the importance of particle shape on induction period, with angular particles exhibiting induction periods that were an order of magnitude lower than those of spheres. Furthermore, the induction period was seen to decrease with increasing particle velocity, or kinetic energy on approach, but increased as the trajectory approached the limit of just grazing the bubble. Particle shape in mineral processing is a consequence chiefly of the mineral type and the type of grinding employed. The results presented herein indicate that attention should be paid to the shape of particles obtained from the grinding operation, besides particle size. Keywords: attachment, bubbles, flotation, induction period, particles, shape effects, surface roughness

Sep 1, 2012

By T. V. Vijaya Kumar

Most of the iron ore washing plants set up in India consist of sizing of the ore by dry / wet screening, washing and classification by screw classifiers followed by multi-stage hydrocycloning of screw classifiers? overflow. The underflow of the hydrocyclones forms the concentrate which is used for pellets making. As the cut-point of hydrocyclones is generally at 20 microns, relatively lower diameter cyclones in a cluster with parallel feeding are used. This is found to, often, result in choking of the spigots, at times, by extraneous material as well reporting along with the slurry. It is observed to lead to sub-optimum performance of the cyclones with loss of iron values into cyclone overflow and thereafter into tailings. Analysis of data of an operating beneficiation plant (Beneficiation Plant - 1, BP - 1) of M/s Jindal South West (JSW) Steel Limited, Karnataka, India over a period of one year indicated that weight recovery of the concentrate from two-stage hydrocycloning was 45% (with respect to feed to the cyclones) and assaying 63.43% Fe, 4.43% SiO2 and 2.32% Al2O3. CSIR - National Metallurgical Laboratory - Madras Centre (NML - MC), India developed flotation process for processing screw classifier overflow with a view to improve the recovery of ultrafine iron values from it. Detailed investigations at laboratory scale flotation column and on-site pilot plant trials proved that the production of the concentrate and productivity of the plant could be enhanced by adopting reverse cationic column flotation technology. It was established that a typical screw classifier overflow analyzing 60.54% Fe, 5.95% SiO2 and 3.67% Al2O3 could be upgraded to 64.21% Fe, 2.64% SiO2 and 2.20% Al2O3 with 82.7% weight and 84.7% Fe recovery. This translates into an increase of 80% in weight recovery of the concentrate compared to what is being obtained, at present, by two-stage cycloning. It had an added advantage of reduced SiO2 in the concentrate. Thus, SiO2 in the final concentrate could be reduced to 2.64% from 4.43% by adopting column flotation. The concentrate so generated meets the stringent specifications, especially in terms of alumina in it(should be less than 2.50%) for pellets making. Later, JSW Steel Limited set up the flotation plant in BP - 1 based on the process developed by NML - MC and was commissioned in 2010. Keywords: iron ore, washing, ultra fines, alumina reduction, column flotation

Sep 1, 2012

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 L. Filippov

"Nickel is an important metal with the total global consumption of about 2 million tons per year. It is sourced from both sulfide and laterite ore, but currently laterites are becoming more attractive for nickel production due to the depletion of high grade nickel sulfide ores. Laterites are generally processed by hydro or pyro-metallurgy and therefore, pre-concentration of nickel before such processes is very important. In this paper the effect different physical methods (including flotation) on the pre-concentration of nickel in laterite ores will be discussed. The ore used in this study was a laterite from South East Asia. Nickel was upgraded using different methods such as magnetic separation, flotation and sizing. The effect of ore mineralogy on choosing the best strategy to upgrade nickel will be discussed. The findings of this project will help to unlock a substantial volume of nickel with significant value from laterite ores.INTRODUCTION Nickel is an important metal with the total global consumption of about million tons per year which has grown rapidly during last decades (Mackey, 2011). Nickel is sourced from two different types of ores, sulfide and laterite. The majority (about 70%) of the world’s nickel resources occur as laterite ores which are often complex, and low grade, and therefore expensive to treat using conventional methods (Xu et al., 2013). Today, nickel laterites are more attractive for production of nickel as the amount of high grade nickel sulfide ores has diminished (Janwong, 2012). Therefore more economic processes to recover nickel from these resources should be developed.It should be noted that nickel laterite mineralogy is complex, and nickel often presents as ultrafine inclusions in a number of mineral phases. Because of the low nickel concentration and variable distribution in these phases, effective upgrading by physical separation processes would be challenging. Researchers have tried to improve nickel laterite flotation recovery by using a number of feed preparation techniques. A summary of the nickel grades obtained using flotation and magnetic separation as reported in the literature is presented in Table 1. It can be seen that only minor nickel upgrades have been reported. Quast et al. (2015) have concluded that the complex mineralogy of nickel laterite ores makes it difficult to achieve any significant nickel upgrading by physical techniques, including flotation. They achieved 40% increase in the nickel content (from 1.0% to 1.4%) at a nickel recovery of 43% (Quast et al., 2015). Various attempts in USA, New Caledonia, India and Australia, to upgrade nickel in laterite using magnetic separation have not been successful (Quast et al., 2015). A recent comprehensive review on topics influencing nickel laterite flotation has shown that further investigations in the flotation of laterite ores are undoubtedly warranted (Farrokhpay & Filippov, 2016)."

Jan 1, 2018

By L. Simpson

South African is a repository of significant deposits of a variety of minerals. The Citigroup confirms this assertion with an estimate of in-situ valuation of US$2.5 Trillion. The mining sector plays an important role in the South African economy. In addition to the mineral resource base South Africa has other comparative advantages. Firstly, South Africa retains major mining companies that participate globally, including Anglo American, Goldfields and De Beers. Their global involvement offers much to the local mining sector and the broader economy. Secondly, government established research councils. The Council for Geoscience (CGS) was established to manage the Geological Survey of South Africa, including the reduction of geo-scientific investment risk. The Council for Scientific and Industrial Research (CSIR) promotes industrial development, including mining technology development. Mintek undertakes mineral research from mineral examination of ores, to extraction and refining technologies and manufacture of end products. Thirdly, South African universities teach and conduct research along the mineral value chain. They have increased their minerals graduates? capacity, thus advancing knowledge and skills. Knowledge and technical progress are behind productivity growth and emergence of competitive advantage. The research and development (R&D) capabilities of industry, science councils and universities, working in unison, will enhance the competitiveness of the South African mining industry. The National System of Innovation (NSI) requires multi-disciplinary, collaborative research. Key R&D elements, including skills and expertise, funding and facilities, must be available to implement a long-term national strategy or programme. Improved international collaboration and partnerships between government, academia and industry driven human resource development (HRD), ultimately develop the critical mass for inter-generational skills requirements. This trend requires an expansion of research collaboration programmes. Decisions involving investments and collaborative actions pertaining to R&D in the sector necessitate an analysis of the South African mineral value chain R&D capability. This paper analyses the evolution of R&D capability from exploration to refining, tertiary education, science councils and industry. The political economy of the evolution of this capability is analyzed in relation to the central role that the South African government plays in creating an appropriate supporting environment and related initiatives to enhance R&D and innovation. Keywords: research and development (R&D), science councils, universities, industry, innovation policy, South Africa

Sep 1, 2012

By J. Quinteros-Riquelme

Despite increasing demand, the supply of silver is limited by its inadequate recovery from ores. Due to its scarcity in nature, its high ore variability and complex mineralogy of current silver deposits, its recovery by mineral froth flotation presents a real challenge for process engineers. A silver ore often contains significant amounts of five to ten different silver minerals and knowledge of the mineralogy is a necessary precursor to flotation testing. In this work, a complex silver ore was treated by using batch laboratory flotation, in an effort to find the best experimental conditions to obtain the optimal silver recovery. Mineralogical characterization of feed samples was conducted using a combination of tools, namely the mineral liberation analyzer (MLA) and inductively-coupled plasma mass spectrometry (LA-ICP-MS), which indicated that most of the silver occurred as ?invisible? silver in pyrite. The pyrite assay of the ore was approximately 4%. The ore was processed in two flotation stages. The first stage, sulphide flotation, aimed to collect a sulphide mineral rich concentrate; then a non-sulphide flotation stage was performed by adding sodium sulphide and collectors to the remaining material in the cell, with the objective of obtaining a pyrite rich concentrate. To reach the target recovery of silver from this ore, various variables were altered. In the first stage: mixed collectors, activators, dispersants, and mainstream inert grinding were assessed. In the second stage, the conditions for sulphidization and subsequent flotation were both investigated. From the grade recovery curves for silver and sulphur it was possible to observe a similar metallurgical behavior for both elements, supporting the results given by the mineralogical characterization. Keywords: silver oxide, froth flotation, sulphidization, mig

Sep 1, 2012

By Diana Drinkwater, Tim Napier-Munn

"This paper argues that, although specialist mineral engineering expertise is essential for the efficient design and operation of mineral processing plants, the environment in which these skills are supplied to the industry has changed forever, and not for the better. Most of the mineral engineering programmes in western universities have died or are dying. The long-service mine site mentors have gone, operations are run on a staffing shoestring so that there is no longer the time (or inclination) for considered decision-making, and the FIFO model has discouraged continuity of optimisation projects and communication between professionals. At the same time the technical challenges of designing and operating effective process plants are increasing. These trends are not going to be reversed any time soon, if ever. The ability to run efficient mineral processing operations has been materially compromised as a consequence. We propose that well-designed professional development can help to recover this situation, and it can be done easily and cheaply. The workplace is the best environment for such skills development. Professional development training should be integrated with normal duties throughout the early years of a graduate’s service (and probably beyond), and the cost should be regarded as non-discretionary expenditure for the business. If such programmes are properly resourced and managed and extended over longer time periods, there will be a measureable rise in the level of technical understanding and competence within companies and a resulting beneficial impact on resource utilisation and thus shareholder value. The paper outlines some of the approaches that we believe will work, and the benefits that we expect will accrue."

Jan 1, 2014

With shortage of sulfide nickel ores, laterite ore was paid more attention by scientists. Because its grade is commonly lower than sulfide nickel ores, laterite ore can not be utilized effectively be-coming the bottleneck of study. Leaching laterite ores from Yuanjing, Yunnan province, organic ac-ids show better selective than sulfide acid in nickel and cobalt recovery. Organic acid has low de-pendent on pH, keeping leaching capability even higher than 3. On the other side, when pH up to 2, sulfide acid can not leach laterite ores any more. After four kinds of organic acid leaching laterite ores, besides citrate, malate and succinate have good leaching and effectively selective capability. Especially, succinate has the best selective leaching capability of nickel and cobalt in four kinds of organic acids for latter anion purification and separation. Isolated from waste water with sugar, Aspergillus niger (zs1) has great capability to produce organic acids and vigorous growth. Laterite ores have been respectively processed by direct-leaching and indirect-leaching. Indirect-leaching gives a better result than direct-leaching. Extraction of nick-el by indirect-leaching reaches 44.3%, far more than that of direct-leaching. Moreover extraction of nickel at pulp density of 5% is higher than that at pulp density of 10%, reaching 63% in 11 days and extraction of cobalt also is 48.1% in the same period. Compared with nickel and cobalt, iron gives low extraction in solution, containing organic acids produced by Aspergillus niger .

Jan 1, 2014

By F. Burat

At the present time, methods of mining and coal preparation produce tones of coal fines. The removal of water from these fines is necessary for economical and technological reasons. Supplementary processes that utilize different physical and chemical methods have been developed to in-crease the productivity of mechanical dewatering processes. Researches have shown that chemical reagents used along with conventional systems diminish moisture and increase the capacity and the yields of the dewatering method. In this study, the parameters of the vibrating screen (incline, frequency, feeding rate and screen size), the effects of the application of additional vertical mechanical vibration and surface active reagents (CTAB, SDS, Umectante B-70 and Kerosene) were investigated. At the end of the optimization experiments, 61.0% moisture was decreased to 42.3%. By keeping optimum conditions con-stant, the experiments have been conducted to determine most effective reagent. 41.2% moisture has been obtained with 5 g/t CTAB at the normal pH of the pulp, which were 7.25. By using vibrating screen with combination of the vertical vibrating mechanism, CTAB gave the best result of 40.7% moisture. Finally, the effect of increased surface area of the screen has been investigated and de-creased the moisture level to 38.7%.

Jan 1, 2014

By Atsushi Shibayama, Toyohisa Fujita, Wan-Tai Yen, Ke-jun Liu

"A gold has been leached with ammonium thiosulfate solution and several leaching conditions have been studied. The leached solution has been recovered by solvent extraction and the optimum conditions have been investigated.SUMMARYIn this investigation, a sponge gold sample (99.92% pure) has been leached with ammonium thiosulfate solution. The effects of CuSO4, (NH4)2S2O3, (NH4)2SO4, NH4OH and retention time on the gold leaching % (extraction %) and thiosulfate oxidation % (consumption %) have been studied. The copper ion acts as a catalyst in gold dissolution. On the other hand, it also accelerates oxidation of thiosulfate (consumption). It was found in this study that the best gold extraction condition was obtained at 43.2 ks with 0.8 – 1.0x103 mol/m3 (NH4)2S2O3, 30 mol/m3 CuSO4, 2.0 – 3.0x103 mol/m3 NH4OH, 0.4 – 0.5x103 mol/m3 (NH4)2SO4, pH 10±0.2 and 150 rpm. The thiosulfate oxidation was about 15% of the initial concentration."

Jan 1, 2003

By A. Gülmez

The complex ore deposit containing fluorite, barite and bastnaesite minerals is located in Beylikova Region of Sivrihisar town of Eskisehir Province of Turkey. The ore contains 40.80% CaF2; 35.35% BaSO4; 2.01%Ce; 1.5% La; 0.39% Nd and 0.1% Th. Barite recovery from this ore by flotation of the HCl leached tailings is presented in this paper. Rare earths are recovered by leaching. The leached residue (tailings) containing fluorite and barite is subjected to froth flotation to recover barite. The effect of pH and collector concentration on the flotation of barite have been studied in this work.

Sep 1, 2012