Abstract: A magnetic separator for mixtures of powdered plastic and metal comprises a housing having an inlet, a base plate and side plates. A plurality of vertically spaced staggered rows of laterally spaced pilot tubes span, extend through and are secured to the side plates to define a circuitous material falling path. An upright tube clearance plate is arranged intermediate the side plates and has a corresponding plurality of vertically spaced rows of laterally spaced apertures, oversized with respect to and loosely receiving the tubes defining clearance apertures. The clearance plate defines on one side an upright plastic feed chamber having an outlet in the base plate. An upright wiper plate is arranged between the clearance plate and one side plate having a corresponding series of apertures snugly receiving the tubes and defining with the adjacent side plate an upright metal feed chamber having an outlet.

Abstract: Particulate material such as sand is classified in two or more classifying devices (13 and 15) which operate on the principle of "hindered settling" each to provide a coarse underflow fraction and a fine overflow fraction. A chosen blend 12 of the underflow fractions is provided by pneumatic control circuitry (FIGS. 2,5,6) which actuates flow control valves (14 and 16) to open, by amounts in accordance with a chosen blend ratio, only when there is sufficient material available for blending.

Abstract: This invention provides a process for the beneficiation of phosphate ores having a magnesia-rich carbonate-containing gangue and a silica-containing gangue, which process comprises subjecting the phosphate ore particles to controlled attrition to remove at least a portion of the magnesia-rich carbonate-containing gangue; and subjecting the phosphate ore resulting from attrition to a plurality of flotations to remove the remaining magnesia-rich carbonate-containing gangue and the silica-containing gangue and to recover a concentrated phosphate product, the flotations including sequentially a phosphate flotation, a silica flotation and a carbonate flotation. Alternatively, the controlled attrition can be employed after the silica flotation and prior to the carbonate flotation.