Short history of mineral processing. Part 2-Separation of Minerals

The method for mineral processing has grown continuously. There are many method of separation of minerals with the purpose to collect precious metals and separate the gangue. One of the important invention is flotation method, the remarkable invention by Irving Langmuir in 1920 as an absorption phenomenon. This write will introduce you the complete story about mineral processing and separation minerals.

Panning of gold is probably the oldest way of separation of minerals particles by gravity. The attraction of iron particles to a certain kind of a naturally-occurring rock near the village of Magnesia near Izmir in Asia Minor was also famous since ancient times. However, it was William Gilbert (1544-1603) the physician to Queen Elizabeth I. He was the one who described this phenomenon as magnetism and the naturally-occurring rock possessing this phenomenon, as magnetite. With the discovery of electromagnetic induction in the nineteenth century, it became possible to have strong magnets capable of separating magnetic from non-magnetic minerals.

The Belmont sorting facility of 1981 was state-of-the-art for colored gemstones at the time, with conveyor belts handling different schist sizes. By 2004, however, Belmont had incorporated state-of-the-art technology in the form of an optical sorter. Courtesy Belmont mine.

Hand sorting

Hand sorting was a common method to pick up the valuable pieces of ore from the gangue. This method was utilise until the mid twentieth century. From the date forward it was expire and being replace by a variety of other methods. Mostly based on electrostatic properties, radioactivity, X-ray fluorescence, etc. Arthur Redman Wilfley (1860-1927) in Arizona invented in 1896 a shaking table for separating minerals while Humphrey spiral came into use in about 1940s.


Flotation is now the most important mineral beneficiation and separation minerals method. Froth flotation at present was perfect by many attempts to float minerals. During early age they using certain oils such as pine oil. Certain mineral particles attach to the oil layer which is lighter than water, hence it was float. For example, the process used by William Haynes in England in 1860. At the beginning of the twentieth century, it was report by Elmore in 1904 and Sulman et al. in 1906.  The use of large amounts of oil was unnecessary and even objectionable for separation minerals. They found that the replacement of some oil by air as the buoyant medium was more advantageous.

Flotation History

In 1909, Greenway, Sulman, and Higgins advanced the art of separation minerals through their discovery of soluble frothing agents such as ketones and alcohols. The agents which permitted still further reduction of the quantity of oils formerly required for flotation. From 1913 to 1922, flotation may to have first commercial success, particularly in the United States. The first commercial plant of importance being that of the Butte & Superior Company placed in operation in 1913. A wide variety of oils, such as wood and coal-tar creosotes, were used as collectors in conjunction with frothers, such as pine oils and rosin oils, for the sulfide minerals. It is to note that all these collectors were of indefinite chemical composition. Bulk sulfide concentrates were recovered in as much as it was not possible to separate on sulfide mineral from another with the known flotation reagents of that era.

The modern era in this technology may be mark by Perkin’s discovery in 1921. He discovered the effectiveness of definite chemical compounds. The compunds such as alpha- naphthylamine and thiocarbanilide in promoting the flotation of sulfide minerals. In the same way, follow by the discovery of Keller and Lewis in 1924 that water-soluble xanthates are effective flotation agents. Since then other discoveries followed such as the use of cyanide as depressant for pyrite and sphalerite in alkaline solution.

Irving Langmuir

Advanced flotation

The theory of flotation as separation minerals was first advanced by Irving Langmuir in 1920. Detected as an absorption phenomenon on the surface of the mineral and the adhesion of the mineral to the bubbles of air forming a froth. The theory was explain further by L.J. Christmann of the American Cyanamid Company in USA in 1930. Application of flotation to non-sulfides has been increasing. Satisfactory results in the treatment of mineral phosphates, of cement rock, of crude salines (such as potassium ores), and also of impure fluorite and barite. Another field of application of flotation is to the making of high- grade iron concentrates from low-grade primary ores and the cleaning of coal.

Flotation was always running in agitation tanks. The suggestion to use columns in flotation was proposed by P. Poutin and R.J. Tremblay in a US patent issued in 1967. It was in 1980 when columns were installed for the first time at Mine Gaspé in Quebec, Canada. It was found out that two columns: one 45.7 cm and another 91.4 cm replaced 13 stages of cells in a molybdenite circuit. Few years late, the mining company in copper industry in Chile adopted column flotation cells in some of its operations. Since then their use became wide spread. The major advantage of the columns is the absence of moving parts hence they are nearly maintenance free. In 1988 the first international conference on column flotation was in Phoenix, Arizona by the Society of Mining Engineers of AIME, to mark this innovation.




Leave a Reply

Your email address will not be published. Required fields are marked *