Mining and Metallurgy Achievements 1929
MINING AND METALLURGY 1929
by SCOTT TURNER, E.M.
Director, U.S. Bureau of Mines
ONE interesting development in the mining field in 1929 has been the steady advance in prospecting methods, by which many valuable mineral deposits heretofore unknown have been discovered.
Remarkable increases in efficiency are reported at various mines developing large low-grade ore bodies. This has been achieved by the application of the caving method of mining and by thorough underground organization. By changing from the usual advancing method to the retreating method, in Michigan copper mines several thousands of feet deep, the former menace of crushing from heavy rock pressure has been removed. At other mines in Michigan, Tennessee, and Canada, ore extraction is started at the lowest levels, the work progressing from the bottom up. This system eliminates prohibitive pressures, saves timber, disposes easily of waste from developments, and gives less inflow of surface waters and greater safety.
Improvements in mine ventilation have added greatly to labor efficiency.
The most important developments in ferrous metallurgy have been the Ashton process for producing wrought iron in large tonnages at low cost, the tremendous increase in the production of stainless steels and irons, the introduction of nitrided steel, and the introduction of tungsten carbide as a machine tool. In nonferrous metallurgy, the advances to be noted include a willingness on the part of industry to invest money to effect small savings in metal recovery and the development of lighter and stronger alloys for aircraft.
In the ore-dressing field, there have been steady developments in flotation and classification, resulting in improved grade of product, thus giving richer feed to smelters which were consequently able to produce more metal per unit of slag and impurities. The flotation of nonmetallic and nonsulphide ores has increased greatly. In secondary crushing, cone crushers are gradually replacing rolls and small gyratory breakers.
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May 18th, 2007 at 12:49 am
[...] The most important developments in ferrous metallurgy have been the Ashton process for producing wrought iron in large tonnages at low cost, the tremendous increase in the production of stainless steels and irons, the introduction of … …more [...]