Reverse flotation : a novel process for the beneficiation of fine coal

The beneficiation of ultrafine coal by froth flotation is a widely used process, and its importance for the treatment of -0.1 mm coal has been appreciated of late in South African coal washing plants. A number of problems adversely affect the efficiency of this process, such as poor liberation, poor floatability, gangue entraiment/entrapment, and high mass recovery which can lead to throughput limitations in coal flotation equipment. Reverse coal flotation is a novel process which has been proposed to address three problems occurring in the conventional, "forward flotation" of coal, namely: high mass recovery, gangue entrainment and the variability of floatability of South African coals. In this process, the entire gangue fraction in the coal would. be floated in a single step process, with the clean coal product reporting as the tailings. To the author's knowledge, no_ such process has been investigated previously for coal flotation. In this thesis, a reverse flotation process for ultrafine coal beneficiation was developed from first principles. In order to obtain a clear understanding and interpretation of experimental flotation results, artificial feed mixtures consisting of blends of "pure" gangue and "pure" coal were used for a large section of the experimental testwork. Having established the technical viability of the process on these artificial mixtures, the flotation work was extended to four South African run-of-mine coals. The study comprised the selection of suitable reagents for reverse flotation and the evaluation of these reagents experimentally. Experimental testwork comprised batch adsorption tests, and flotation tests in a conventional, sub-aeration laboratory batch cell and in a laboratory column flotation cell. The process was evaluated in terms of coal recovery into the product and gangue removal in the waste stream, and its metallurgical performance was compared to conventional flotation using both the artificial feeds and r.o.m. coals.

Grantor dc:publisher.institution

Department of Chemical Engineering

Year dc:date.issued

1991

Author dc:creator

• Stonestreet, Paul

Advisor dc:contributor.advisor

• Franzidis, Jean-Paul

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/11427/21990

OAI identifier oai:identifier

oai:open.uct.ac.za:11427/21990