Status : Verified
| Personal Name | Regidor, Hanna Czarise E. |
|---|---|
| Resource Title | Electrochemical oxidation and dissolution of refractory (Benguet) gold concentrate in hypochlorite solutions |
| Date Issued | 23 January 2019 |
| Abstract | In view of the decreasing availability of free milling gold ores today, the development of processes that can treat refractory ores are important. Alternative lixiviants have then been studied, and the most promising is chlorination. The process is capable of both dissolving the old and oxidizing the ore, which removes the "refractory" nature of the ore. In this study, a two stage leaching process has been proposed and conducted. The first stage consists of oxidation using hypochlorite-bearing reagents at alkaline conditions for 3 hours. Solution pH is then lowered for the second stage and fixed amounts of calcium hypochlorite and sodium chloride is added every 10 minutes for 4 hours. X-ray diffraction patterns of the residue from the first stage leaching and second stage process achieved higher oxidation of the iron sulfides, achieving a 36.3% decrease in the amount of pyrite. A one stage leaching process using the second stage process was also conducted for comparison, and results show that the two-stage leaching process was more effective, achieving 92.4% gold recovery while the one stage leaching process only achieved 68% gold recovery. Based on the results, optimization for the first stage oxidation process is important in leaching refractory gold concentrates. Statistical screening tests were done to determine the significant factors, and it was found that the factors hypochlorite concentration, percent solids, and oxidation time were significant. Three level parameters of these factors were considered in the optimization tests, and the solution obtained showed that a gold recovery of 83% can be obtained at the end of the oxidation stage with the following oxidation parameters: 258 minutes of oxidation, 0.6 moles of hypochlorite and 28% percent solids. SEM-EDS of the residue from the oxidation runs suggests a product layer diffusion oxidation process, and powder XRD patterns validated that oxidation took place. |
| Degree Course | MS Metallurgical Engineering |
| Language | English |
| Keyword | electrochemical dissolution; hypochlorite solutions; refractory gold ore |
| Material Type | Thesis/Dissertation |
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Category : I - Has patentable or registrable invention of creation.
Access Permission : Limited Access