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Biooxidation of sulphide minerals has become an important method for the pretreatment of refractory gold ores. More over, bioleaching of the mi nerals with thermophilic microorganisms is attracting increasing interest as a promising alternative process. In this study, the biooxidation of an arsenical refractory gold sulphide concentrate using extreme thermophiles is examined. The concentrate contained 100.84 g/t Au, 31.8% pyrite (FeS2), 10.9% arsenopyrite (FeAsS), 0.2% chalcopyrite (CuFeS 2), 37.3% quartz (SiO2) a...

The paper deals with decontamination of sediments polluted by persistent organic pollutants in the influent stream of Ce rny prikop in Ostrava, the Czech Republic. Flotation is used as the first stage treatme nt method when the individual contaminants accumulate in the flotation concentrate. C onsequently, bacterial leaching applying the bacteria of genus Pseudomonas and Rhodococcus is used as the second treatment method. The results imply that the combinat ion of both the methods is very effective and leads to a ...

Feldspar ores occur usually together with quartz, micaceous minerals and some amount of coloured impurities. For fu rther utilization of feldspar is necessary to effectively remove colouring gangue minerals. The main me thod of feldspar ores treatment is froth flotation. In this paper the emphasis is put on efficiency of pH changes and varied dosages of flotation reagents in application of laboratory flotation.

This paper presents a new approach to evaluation of coal with implementation microwave extraction. It is know from literature that coal is a chemically and physically extremely complex and heterogeneous material, consisting of organic (carbon) and inorganic (minerals) constituents. Our attention was intent on the study of influence of Soxhlet and microwave-assisted extraction in the open-vessel and closed-vessel system, respectively. The microwave extraction (MAE) was realised in microwave furnace with using diffe...

Criteria of assessment of surface energy during the minerals disintegration are substantiated in the paper. Values of mechanochemistryactivation criterion of disintegration process are experimentally de fined for a number of gold-bearing ores of the Far Eastern region. It is established that directed changing of surface mineral characteristics makes possible prediction and optimization of technological parameters of ore crushing and Пѓ parameter (surface tension coefficient) and can be a regulated parameter of con...

In the article is a brief description of the methods of thermal analysis, description of bentonite deposits and treatment of this ma terial. Also, this te xt is discussed the practical application of thermal analysis to evaluate materials that can be reused as secondary raw materials in various industries. This method allows both quantitative and qualitative evaluation of a sample. Examples of such material may be bentonite, its evaluation of thermal analysis is presented in this article.

The hydrometallurgical process for obtaini ng alumina by Bayer process bauxite is getting significant amounts of red mud (0.8 - 2 t / t Al 2O3). It is deposited in dumps which can cause danger for environment mainly due to the alkali content ( pH = 8-13) and small dimensisons of particles (less than 60 microns). Chemical and mineralogical composition of red mud bauxite is closely related to type of the bauxite used as raw material and processing conditions determined by some peculiarities of applied technology (pr...

In this work, dissolution of Ni and Fe in sulfuric acid medium under the influence of sodium fluoride was studied. The samples of the nickeliferous late ritic ore were taken from Eski şehir (Karaçam) region of Turkey. The effects on the nickel and iron dissolution rates of stirring speed, sulfur ic acid concentration, sodium fluoride concentration, reaction temperature were investigated. In order to investigate the effects of leaching temperature range of 30-50 °C the shrinking core model was applied by using t...

In this study, the boric aci d extraction from colemanite in ammonium chloride was studied and the effects of parameters such as the leaching temperature, ammonium chloride concentration, solid/liquid ratio a nd leaching time were investigated on the boric acid extraction from colemanite. Statistical design of experiments and the analysis of variance were carried out. The experiments were performed in a 500-mL cylindrical glass reactor equipped with a mechanical stirrer, a thermostat for controlling the leaching t...

A detailed study has been conducted to investigate the leaching behavior of low-grade secondary type, uranium minerals under alkaline conditions. Uranium mapping analysis indicated the significance of each particle size to the leaching process. Owed to its significance, particle size effects were examined by two different experimental schemes: classical plate agita tion and bottle roll te sting. Other infl uencing variables such as agitation time and concentration of used lixiviants, were also considered. Results ...

In this study, nickel extraction from Karaçam (Eskisehir) region laterites by hydrochloric acid leaching is ai med. The mineralogical analysis showed that the ore sample contains goethite, hema tite, wustite, retgers ite, gaspeite and clay type minerals together with quartz. The effects of various parameters such as leaching time, stirring speed, acid concentration and leaching temperature on nickel recovery were determined. The shrinking core model was applied to the results of experime nts investigating the eff...

The bauxite is not processed through the usua l processes of ore en richment because of the mineralogical composition and structure, the intergrowths of minerals being very fine. Mineralogical characterization is very important to choose the method of extracting alumina from bauxite. This paper presents the mineralogical st udy of a hydrargyllitic bauxite from Sierra Leone and of the red mud resulted after extraction of alumina by Bayer method. The mineralogical characterization of red mud is needed to choose the ...

Regularities of molybdate acid leaching process in sodium carbonate solutions depending on temperature and concentration of reagents are identified. Also current intensity influence on electromembrane process parameters and influence of mass transfer of molybdenum ions on electrolysis of sodium molybdate solutions are revealed.

We present new flotation agents, KSK- n, for the benefication of polymetallic sulfide ores in this work. The KSK-n reagents belong to xanthates, but contain a heterocycle in their structure and due to that exhibit both, the collector and frother properties.

Conducted research of processes of dry an d wet mechanoactivation of wolframite concentrate and structural modifications were determined. With a purpose of maximum transference of tungsten from obtained after-sintering mixtures into solution, investigation wa s conducted, conditions of hydro desalination were determined and technological regime of the process was developed.

The paper deals with the verification of the possibility of using the froth separation to separate highly concentrated coarse-grained black coal slurry. For laboratory research samples of raw coal with a grain size fraction of 0,2 - 2 mm from the Paskov Mine were used. The achieved se paration results confirmed the ability of froth separation to separate coarse-grained highly concentrated sl urry. The coal slurry in concentrations of 332 kg.m -3, 400 kg.m-3, 500 kg.m -3, 600 kg m -3, 668 kg m-3 was successfully se...

Researches of ilmenite reduction kinetics defining intensity of process course are carried out for many years. Main characteri stic is concentrate reducibility degree, characterizing process speed in concrete conditions. Ilmenite reduction process is very complicated, and its speed depends on many factors - oxides nature, temperature and degrees of concentrate grinding. Iron complicates ilmenite concentrate use in its chlorination process for obtaining titanium tetrachloride - an initial product for obtaining of s...

The paper deals with the study on pyrite liber ation from talc raw ma terial. The material comes from deposit nearby Gemerska Poloma village (Eastern Slovakia). A lumpy material was subjected to crushing, grain si ze and float-sink analyses. Heavy and light products were also assayed. XRD study of sel ected products of float-sink analysis was carried out. Thus, it was found that iron and sulphur concentrate in a grain size classes of 0.5-3mm, above all in 1-2mm. The highest mass yield of heavy product was attained...

The biotechnological methods have wide application area in the remediation of heavy metals from the waste waters. This study presents the results of the biological-chemical activation of coal waste from the Cigel deposit (Slovakia) by selected species of microorganisms, as well as: Aspergillus niger, Asperg illus clavatus, Penicillium glabrum and Trichoderma viride . The quantitative maceral composition has been investigated. The complex maceral analysis shoved that microorganisms preferentially disrupt the struct...

The national and international economic crisis has increased the interest in utilizing coal to produce electric or thermic energy, but that means also an increased pollution. According to the U.E. normative, Romani a’s environmental problems with the SO X, NOX, CO, CO 2 emissions from the th ermoelectric plants will be partially solved by 2012. However there will remain some important sources of pollution such as ash and breeze deposits, which have a negative impact upon the microclimate and upon all the environ...