Process Mineralogy of Laga Dambi Gold Ore, Oromiya, Southern Ethiopia
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2023-09
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Abstract
To understand gold ore processing, the important mineralogical properties of Laga Dambi gold ore was described qualitatively and quantitatively. This is required to determine the parameters of gold ore grade, ore composition (elemental and mineralogical), and concentration of any valuable minerals, nature and concentration of minerals detrimental to the processing. One 75mm x50mm size polished thin section was supplied from each sample and was examined by conventional transmitted and reflected light polarizing microscope to determine the distribution of gold in the samples. Sub samples (500g) of each ore type were ground to 1mm and the heavy minerals concentrated using gold pan. The concentrates were submitted for mineralogical analysis to determine the distribution and particle size of gold in the samples. XRD, XRF and Geochemical analysis was carried out for gold mineralogical characterization and its concentration determination. From the data obtained it can be concluded that, gold is the most valuable element in the ore. The samples are all well graded and show excellent liberation. Sulphide mineralization is coarse within all the samples The pyrrhotite is the most abundant sulphide in all the samples, with the exception of Mse T5 where it is second in abundance to pyrite.Samples OP T1 and MSe T5 containing the highest concentrations of sulphide minerals. The gangue in the samples is dominated by crystalline quartz and mica (muscovite, biotite and phlogopite). Gold was identified in all but the Op T1 head sample. Pyrroyite, pyrite, and chalcopyrite are the most frequent interfering minerals that either consume cyanide or oxygen, or both, and adversely affect the rate or extent of gold leaching. From mineralogical point of view liberation size of gold can be determined to be120μm. from XRD and XRF techniques quartz was predominant gangue minerals in all types. Ankerite, dolomite and plagioclase feldspar were also present in minor constituent. All samples contained low levels of base metals, with the possible exception of OP T3, which are not likely to hinder processing mechanism.
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Gold ore, gangue minerals and sulphide minerals