Depression of Pyrite Flotation by Microorganisms as a Function of pH

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It has been reported in the literature that microorganisms, particularly the bacteria Thiobacillus ferrooxidans, can depress the flotation of pyrite particles during coal flotation. The study reported in this paper was conducted to answer two questions that have not been adequately addressed in the literature: 1. How much ability do the bacteria have to depress pyrite flotation in a normal high-sulfur bituminous coal, under flotation conditions that are commonly used industrially; and 2. What is the effect of pH on the depression of coal-pyrite and mineral-pyrite flotation by microorganisms. Results are given which show that, for a randomly-selected coal sample under normal coal flotation conditions, and particularly at near-neutral or alkaline pH, pyrite depression by microorganisms was of no significant benefit. © 1993, Elsevier B.V.

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Coal Science and Technology