Hypochlorite leaching of gold ore
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Date
2018-06
Authors
Mohamad Za'im Mohamad Zaidi
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Abstract
In this research project, the bulk gold ore sample received from Kuala Lipis,
Pahang was used. The gold ore was first sieved to determine the particle size distribution
of the gold ore sample. Result from sieving shows that only 11.20 % of the gold ore sample
is -75 µm. The bulk gold ore sample then was ground to obtain 80 % of the sample passing
-75 µm. Before conducting the hypochlorite leaching with two different parameters which
is the temperature and concentration of calcium hypochlorite [Ca(OCl)2], the sample
undergoes characterization and mineralogical study. The study was done to determine the
chemical composition, major phases presence, and the elements that associated with the
gold ore sample using XRF, XRD, SEM and EDX. From XRF, XRD, SEM and EDX
analysis, it was found that distribution of gold is partly arsenopyrite (FeAsS) and quartz.
The gold content in the gold ore sample is 6.91 g/t which was obtained from assaying
method. BLEG method was used to determine the free milling gold which is 4.58 g/t.
From the comparison of the percentage of gold leached between the variables which is
temperature at 45 °C and 55 °C and the concentration of calcium hypochlorite which is
0.25 M and 0.75 M, the best condition to conduct hypochlorite leaching was using 0.75
M of calcium hypochlorite at ambient temperature, 27 °C. This condition gave the highest
percentage of gold leached with 72.20%.