Gravimetric Concentration Process of Fine Grades of Ores in a Two-Stage Static Apparatus with Two Spirals.

When relatively fine ores are treated, it is found that in a standard apparatus of the static type, a neutral zone appears which makes it difficult for the process to function continuously, as the ore accumulates in it. In the new two-stage apparatus, the deeper part upstream of the trough comprises a spiral independent of that of the less deep downstream part. The tests have shown that the process was well adapted to the following ores: magnesite, dolomite, iron ore, diamonds, antimonyore, chromite and coal, as well as a large number of carbonates after carbonate removal and hydration. The process can also be used in the preliminary concentration phases of lead and zinc ores and of copper ores.