| 摘要 |
Intermixed divided materials are separated into three or more fractions of different specific gravities by the use of two or more heterodense suspensions, the solid constituent or constituents of the primary suspensson being one or more of shale, limestone, low-grade fluorspar, slag or low-grade ironstone, and the solid constituent or constituents of the secondary suspension being different from that or those of the primary suspension and being such as to effect separation at a specific gravity higher than that employed in the primary suspension. The solid material of the secondary suspension may be one or more of magnetite, rolling-mill scale, sintered iron ore or other oxide of iron. In washing coal, separation may be effected in the primary suspension to give primary floats, primary sinks and, if necessary, one or more primary middlings, the primary sinks being then washed in a secondary suspension. More than one primary and more than one secondary separation may be effected and the suspensions may have specific gravities of or less than 1.6 and greater than 1.6 respectively. |
