Recovery of Pyrite from the Coal washery rejects from Nowrozabad

Abstract

Two pyrite-bearing rejects obtained during washing tests with Nowrozabad coal were received for the concentration of pyrite. Batch tests were carried out with the sample at cut density 1.6, assaying 6.8 percent pyrite S, and consisting of coal, pyrite, silica grains, altered feldspar, muscovite mica and a few grains of gypsum as the principal minerals. Jigging at -4 mesh rejected about 77 percent by weight and yielded a middling product containing 89 percent of the sulphur in the feed. Jigging followed by tabling of the jig-middling produced a table concentrate assaying 41.7 percent S and 6.4 percent C with a sulphur recovery of 64.4 percent. Jigging followed by flotation of the jig-middling yielded a flotation concentrate assaying 40.5 percent S and 9.1 percent C, with a sulphur recovery of 62.1 percent, the flotation concentrate thus being higher in carbon content than the table concentrates. The sample for pilot plant tests obtained at a cut density 1.5 was treated in a liquid of sp. Gr. 1.58 producing a sink at -4 mesh followed by tabling of the jig-middling at -28 mesh produced a concentrate assaying 44.0 percent S and 5.6 percent C with an actual sulphur recovery of 50.3 percent, but this could be expected to improve to about 60 percent by using multi compartment ji is in practice, in which case the jigging loss could be brought down to about 12 percent, as indicated by batch tests. The results given in the appendix at the end of the report relate to a one ton sample of rejects obtained from actual plant trials at Jamadoba Washery with a truly representative sample of the coal. This sample was received after the investigation on the two earlier samples was completed and hence reported separately. Tests conducted on this sample have confirmed that almost similar results to those obtained from the earlier samples could be obtained through the last sample was of a slightly lower grade (5.52% S).