Facilitated leaching of pyrite from a refractory gold ore by Thiobacillus ferrooxidans ATCC 13661

Date

10-1990

Degree

Bachelor of Science in Chemistry

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Ernesto J Del Rosario

Abstract

Thiobacillus ferrooxidans ATCC 13661 was used to upgrade a refractory pyritic gold ore by its leaching activity on the pyritic minerals that surround the gold particles. The efficiencies of standing and shake flask leach techniques were assessed as well as the effects of the initial pH of the medium, aeration, and carbon dioxide supplementation on the leaching ability of 1. ferrooxidans. Results demonstrated the suitability of microbial leaching as an alternative to the present expensive and environmentally hazardous preoxidation treatments for refractory gold ores prior to cyanidation. The use of high cell concentrations (=.: 20% v/v 5.0 x 10" cells/ml) as inocula was found to be effective in bringing about microbial leaching. Sterile standing and shake flasks gave final iron extraction values of 0.13 and 0.18% respectively, while inoculated standing and shake flasks yielded 0.14 and 2.92% respectively. This confirmed the catalytic effects of T. ferrooxidans on the extraction of pyrite from the refractory gold ore and demonstrated the efficiency of the shake flask leach technique over the standing flask leach technique. The initial pH of the medium was found to have no significant effect on the leaching ability of T. ferrooxidans. Maximum iron extraction rates of 35.62, 34.58 and 34.55 mg Fe/L/h were obtained for leaching media having initial pH values of 1.80, 2.30 and 2.80, respectively. Aeration and carbon dioxide supplementation doubled the rate of pyrite extraction from the refractory gold ore. A final iron extraction value of 5.52% was obtained for aerated treatments supplemented with carbon dioxide.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 1990 C4 G37

Document Type

Thesis

This document is currently not available here.

Share

COinS