Characterisation of Biooxidation Feed and Products for Improved Understanding of Biooxidation and Gold Extraction Performance
Grace Ofori-Sarpong,
Ahmed-Salim Adam,
Richard Komla Asamoah,
Richard Kwasi Amankwah
Issue:
Volume 5, Issue 2, June 2020
Pages:
20-29
Received:
13 March 2020
Accepted:
2 April 2020
Published:
15 May 2020
Abstract: This paper presents a study on characterisation of refractory ore, biooxidation feed and product, and cyanidation tailings with the aim of understanding the causes of excessive continuous frothing, incomplete sulphide oxidation, high reagent consumption, high cyanidation residues and low overall recovery as encountered in biooxidation of refractory ores. Techniques involving carbon and sulphur speciation, Quantitative X-Ray Diffraction (QXRD), Scanning Electron Microscopy (SEM) and Optical Microscopy (OM) were used to characterise the ore samples, flotation concentrate (BIOX® feed), biooxidised product (BIOX® CIL Feed) and cyanidation tailings (BIOX® CIL Tails) from a biooxidation plant. The main minerals present in the ore were quartz (45%), chlorites (21%), plagioclase feldspar (13%), dolomite (5%), pyrite (2%) and mica group (2%). The flotation concentrate recorded 18% mica, and this was responsible for excessive frothing in the biooxidation circuit as confirmed by the QXRD analysis. The carry-over froth to the CIL circuit led to short-circuiting of poorly leached material into the cyanidation tailings, resulting in high cyanidation residues. Secondary refractory minerals; gypsum and jarosite, which were observed in the biooxidation product by the QXRD, have the potential to coat unreacted sulphide particles, leading to incomplete sulphide oxidation as observed here. Partially oxidised sulphides led to high consumption of reagents such as oxygen and cyanide during cyanidation. Gypsum and jarosite also encapsulated gold particles as observed in the BSED analysis. Coated gold particles had reduced access to lixiviants during the subsequent cyanidation process, leading to high leach residues. The biooxidised product (BIOX® CIL Feed) also recorded a high organic carbon content of 6.67, while analysis by BSED revealed the presence of graphitic carbon and coatings on gold surfaces; an indicator for high preg-robbing activities during cyanidation of the concentrate. Preg-robbing indices of 64.4% and 72.7% were recorded for the flotation concentrate (BIOX® feed) and BIOX® CIL feed respectively. The overarching effect of all the observations is a decrease in overall gold recovery.
Abstract: This paper presents a study on characterisation of refractory ore, biooxidation feed and product, and cyanidation tailings with the aim of understanding the causes of excessive continuous frothing, incomplete sulphide oxidation, high reagent consumption, high cyanidation residues and low overall recovery as encountered in biooxidation of refractory...
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Phytoremediation of Nickel, Lead and Manganese in Simulated Waste Water Using Algae, Water Hyacint and Water Lettuce
Sani Nasiru Alhaji,
Sulaiman Asmau Umar,
Sokoto Muhammad Abdullahi,
Shehu Kasimu,
Salisu Aliyu
Issue:
Volume 5, Issue 2, June 2020
Pages:
30-36
Received:
14 July 2020
Accepted:
4 August 2020
Published:
13 August 2020
Abstract: The increase in industrial and artisanal mining and mineral processing activities has led to a surge in the quantity of hazardous materials, typically heavy metals that are released into the environment. These hazard materials, when discharge in water bodies, poses serious risk to humans, animals and environment. Phytoremediation is one of the cost effective methods use in the removal of these pollutants from environment. Several plants have been investigated for their phytoremediating potentials. In this paper, the phytoremediation potential of algae, water hyacinth and water lettuce for the removal of Ni, Pb, and Mn was demonstrated. Plants of equal size were grown in aqueous medium and supplemented with different concentration (1.0 mg/dm3, 3.0 mg/dm3 and 5.0 mg/dm3) of multi component metal solution for 15 consecutive days. All the plants revealed a very good accumulation potential, with the accumulation of metals shown to increase with an increase in the initial concentration of the metal solution. At all levels, the plants accumulated the metals more in the root than in shoot except for Mn in water hyacinth. The result showed that water hyacinth was able to accumulate Pb better, while water lettuce showed more preference for Ni and Mn. All the three plants can be used in remediating waste water. Hence, water hyacinth, water lettuce and algae are a promising biomass for phytoremediation.
Abstract: The increase in industrial and artisanal mining and mineral processing activities has led to a surge in the quantity of hazardous materials, typically heavy metals that are released into the environment. These hazard materials, when discharge in water bodies, poses serious risk to humans, animals and environment. Phytoremediation is one of the cost...
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