Journal of Mining and Metallurgy, Section A: Mining – vol. 57 A – 2021


Author(s): A.W. Boroh, K.Y. Sore-Gamo, M. Ayiwouo Ngounouno, I.B. Gbambie Mbowou, I. Ngounouno

doi:10.5937/JMMA2101001B

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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Author(s): G.P. Dvoichenkova, V.V. Morozov, E.G. Kovalenko, Y.A. Podkamenny

doi:10.5937/JMMA2101019D

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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Author(s): W. Xia, W. He, J. Sokolović

doi:10.5937/JMMA2101027X

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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Author(s): V. Stanković, D. Božić, M. Gorgievski, G. Bogdanović, M. Žikić

doi:10.5937/JMMA2101033S

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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Author(s): Lj. Tankosić, S. Sredić

doi:10.5937/JMMA2101043T

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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