GB887491A - Magnetic separation processes - Google Patents

Abstract

887,491. Magnetic separators. STAMICARBON N.V. May 12, 1958 [May 16, 1957], No. 15198/58. Class 117. Before subjecting a liquid containing magnetic and non-magnetic particles in suspension to a magnetic separating process, the suspension is separated into fine and coarse fractions, both fractions then being fed separately but simultaneously to spaced positions of a magnetic separator. As shown a screen 10 of spaced bars having 0À5mm. slots between them is used to separate particles of a suspension into fractions of different sizes, the underflow, comprising about 90% of fine magnetite, being collected in a tank 11, and the overflow, containing coarse non-magnetic particles and 10% of the magnetite, being led direct to the region where the surface of a drum of a magnetic separator 12 enters a tank 18; the underflow is fed to the region on the opposite side of the drum. The suspension comprising substantially only magnetite is pumped to a tank 3 which also collects the separating suspension from screens 2 for treating coal and shale fractions accompanied by separating suspension. A demagnetising coil 14 may be provided, and the suspension from the tank 3 is returned to the main separating apparatus 1. Screens 5 have water sprays 6, 7 to wash the suspension from the coal and shale which is then discharged at D and E respectively. A hydrocyclone 17 treats the non-magnetic fraction obtained from the separator 12, the resulting water being used for washing. The fraction F may be subjected to further treatment and the specific gravity of the suspension in the apparatus may be adjusted by adding water at G. Instead of the coarse and fine fractions being separated by the screen 10 and as described in Specification 791,520, means as described in Specifications 791,857, 791,858 and 791,859 may be used. Both fractions may be fed to the separator side by side across the width of the separator.