Froth Flotation - History

History

Initially, naturally occurring chemicals such as fatty acids and oils were used as flotation reagents in a large quantity to increase the hydrophobicity of the valuable minerals. Since then, the process has been adapted and applied to a wide variety of materials to be separated, and additional collector agents, including surfactants and synthetic compounds have been adopted for various applications.

William Haynes in 1869 patented a process for separating sulfide and gangue minerals using oil and called it bulk-oil flotation. In 1885 Carrie Everson expanded upon this and patented a process calling for oil but also an acid or a salt.

The first successful commercial flotation process for mineral sulphides was invented by Frank Elmore who worked on the development with his brother, Stanley. The Glasdir copper mine at Llanelltyd, near Dolgellau in North Wales was bought in 1896 by the Elmore brothers in conjunction with their father, William. In 1897, the Elmore brothers installed the world's first industrial size commercial flotation process for mineral beneficiation at the Glasdir mine. The process was not froth flotation but used oil to agglomerate (make balls of) pulverised sulphides and buoy them to the surface, and was patented in 1898 with a description of the process published in 1903 in the Engineering and Mining Journal. By this time they had recognized the importance of air bubbles in assisting the oil to carry away the mineral particles. The Elmores had formed a company known as the Ore Concentration Syndicate Ltd to promote the commercial use of the process worldwide. However developments elsewhere, particularly in Australia by Minerals Separation Ltd., led to decades of hard fought legal battles and litigations which, ultimately, were lost as the process was superseded by more advanced techniques. Charles Butters, beginning about 1899, and working with both the Elmores and Minerals Separation's representative E.H. Nutter developed what was known to contemporaries as the "Butters Process". The flotation process was independently invented in the early 1900s in Australia by Charles Vincent Potter and around the same time by Guillaume Daniel Delprat.. This process (developed circa 1902) did not use oil, but relied upon flotation by the generation of gas formed by the introduction of acid into the pulp. In 1902, Froment combined oil and gaseous flotation using a modification of the Potter-Delprat process.

Another process was developed in 1902 by Cattermole, who emulsified the pulp with a small quantity of oil, subjected it to violent agitation, then slow stirring which coagulated the target minerals into nodules which were separated from the pulp by gravity. This was the basis of the Minerals Separation Ltd. process. By 1904, the MacQuisten process (a surface tension based method) was developed but this would not work when slimes were present. in 1912 Hyde modified the Minerals Separation Process and installed it in the Butte and Superior Mill in Basin, Montana.

John M. Callow, of General Engineering of Salt Lake City, had followed flotation from technical papers and the introduction in both the Butte and Superior Mill, and at Inspiration Copper in Arizona and determined that mechanical agitation was a drawback to the existing technology. Introducing a porous brick with compressed air, and a mechanical stirring mechanism, Callow applied for a patent in 1914. This method, known as Pneumatic Flotation, was recognized to revolutionize the process of flotation concentration. A detailed description of the history of flotation and this process can be found in Callows "Notes on Flotation" found in the Transactions of the American Institute of Mining Engineers; Vol 53-54, originally presented in New York in February 1916. The AIME presented Callow the James Douglas Gold Medal in 1926 for his contributions to the field of flotation.

In the 1960s the froth flotation technique was adapted for deinking recycled paper.