| 摘要 |
1,123,597. Flotation. ESSO RESEARCH & ENG. CO. 17 June, 1966 [8 July, 1965; 19 Jan., 1966], Nos. 29063/65 and 2540/66. Heading B2H. Powdered coal or another mineral e.g. bauxite, phosphate rock, fluorspar, iron, copper, lead or zinc ores, is mixed with water in a vessel 1 and metered by a pump 2 into a line 3, where it is mixed with a volatile organic liquid, e.g. pentane, liquid butane or propane, which may also contain a less volatile liquid e.g. fuel oil such as kerosene, gas oil, phenol extracts, or coal tar. The volatile organic liquid aqueous coal suspension may be agglomerated in the line 3 and/or on entry into a closed vessel containing an inert atmosphere (which may be the exhaust from a dieseldriven heat pump). Here it is heated as by a steam coil 20 from the heat pump. Alternatively the light liquid may be evaporated by pressure reduction. The coal agglomerates as a froth, is picked up by a scoop 6 and fed to a rotary screen 7, which has coarse and fine mesh regions 8, 9. Coal agglomerates are retained in the screen 7 and the water drains into the vessel, the ash sinking to the bottom. Evaporating organic liquid is condensed at 13 by cooling with a refrigerating coil 14 cooled by the heat pump. De-ashed and de-watered coal is delivered via the seal 11 and hood 12. The condensed organic liquid is fed by a line 15 to a pump 4 and recirculated, and fuel oil e.g. kerosene is metered by a pumped 19. The ash is drawn off and filtered at 17, the water being returned to the vessel 1. The screen may be replaced by a vacuum filter drum. Alcohol additives, e.g. cetyl alcohol may be used together with flotation reagents, viz. oleic acid, sodium carbonate, lime, sodium ethyl xanthate, sodium alkyl sulphates, sulphuric acid, dextrin, starch, terpineol and phenol. |
