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Abstract
This paper is devoted to determining whether the addition of geological information can improve the resource estimate of mineral resources. The geochemical data used come from 116 drill holes in the Nkout East iron deposit in southern Cameroon. These geochemical data are modeled on Surpac and Isatis softwares to represent the 3D geochemical distribution of iron in the deposit. Statistical analysis and then a variographic study is performed to study the spatial variability of iron. Estimation domains were defined based on the results of geological and geochemical analyses. Four domains were determined. These domains are the saprolitic domain in particular; the poor domain or fresh rocks such as amphibolites, granites, and gneisses; the rich domain or oxidized rocks (BIF) and the metasediment domain. Block modeling of the deposit is performed to estimate the resource. The grade of each block was estimated by using ordinary kriging and composites from each domain. This study also consisted of comparing two types of estimate, notably the domain estimate and the global estimate. The cross-validation made it possible to authenticate the obtained models. From this comparison, the domain estimation brings more precision the global estimate precisely on the error analysis while if we take into account the point clouds of the predicted and estimated values, the estimation by geochemical modelling provides the best results.
Key words: Information effect; Support effect; Geological domain; Geochemical modelling.
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Abstract
The reason for diamond loss in foam separation process consists in the fact that the diamond crystals fed to the foam separation are coated with hydroxides and carbonates. A combined method to restore the diamond hydrophobicity through thermal and electrochemical destruction of the mineral coat was proposed. This method provides for the conditioning stage in the foam separation process to enable decreasing the amount of the minerals coating diamonds surface from 3 to 10 times. Technological research showed that using products of diaphragm less electrolysis of recirculating water, with the thermal treatment of the foam separation feed enables increasing the recovery of diamonds in the foam separation concentrate from 76.5% to 83.7%.
Key words: Diamonds; Foam separation; Heat treatment; Recirculating water; Conditioning.
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Abstract
The sulfur in coal not only influences the coke quality but also pollutes the environment during the combustion. The desulfurization of high organic sulfur coal is a key issue in coal cleaning science. As the pyrolysis has been used in low rank coal conversion to obtain gas/liquid products and coal char, the desulfurization effects of pyrolysis on the low rank coal with high organic sulfur requires further studies. This study investigated the desulfurization performance of high organic sulfur low rank coal by the pyrolysis and the changes in the coal calorific value and sulfur forms during the pyrolysis. The XPS was applied to analyze the changing regulation of sulfur that forms on coal surface. The results indicated certain amount of FeS was newly created during the pyrolysis and high amounts of sulfate sulfur was transferred to pyrite sulfur and formed more FeS2 when compared to the distribution of raw coal. The total sulfur content of coal was reduced from 2.32% for raw coal to 1.68% for 700 °C pyrolysis coal and then the pyrolysis temperature had little effect on the sulfur content. The net calorific value (at constant volume and air-dry basis) was increased from 17.38 kJ for raw coal to 24.35 kJ for 700 °C pyrolysis coal. The pyrolysis temperature of 700 °C may be the best pyrolysis temperature for both low sulfur content and high calorific value.
Key words: Coal desulfurization; Pyrolysis; XPS; Calorific value; Sulphur content.
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Abstract
Through this study special attention was paid to AMDs, originating from copper mines, containing different heavy metal ions, and a certain amount of sulphuric acid. The research was conducted on the territory encompassing the RTB Bor mines (now Serbia Zijin Bor Copper). The AMDs occurrences, their water composition, metal potential, and impact on the local surface waters were determined. The major amount of mine waters flow into the Krivelj River damaging extremely its water quality. The research also included monitoring the Timok river water quality along its course from the Krivelj River inflow to the confluence with the Danube. Evaluating the metal losses, it was found that every year around 360 tons of copper, >500 tons of iron, and 30 tons of zinc from mine waters are lost, as being transported via the Krivelj River to the Timok and then to the Danube.
Key words: Heavy metal ions; Mining wastes; Mine water; AMD; Water pollution.
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Abstract
The paper represents a part of research conducted with the aim of examining the possibility of applying selective flocculation of goethite from sludge that occurs in the process of iron ore production. The aim of this study was to compare the influence of polyacrylamide and sodium oleate as a flocculant on the settling behavior of goethite under different conditions. The paper presents the results of the research on the influence of the flocculants based on polyacrylamide and sodium oleate, as well as pH values on the settling rate of a natural goethite sample. The results showed that the settling rate of goethite was influenced by pH value and the type of flocculant, while the concentration of flocculant did not significantly affect the settling rate. Measurements of zeta potential showed the effect of flocculants on the surface of the goethite.
Key words: Goethite; Flocculation; Settling rate; Zeta potential.
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