WET-CLASSIFYING METHOD FOR RECOVERY OF CARBON AND IRON-BEARING PARTICLES

WET-CLASSIFYNG METHOD FOR RECOVERY OF CARBON AND IRON-BEARING PARTICLES A method for separating carbon and iron bearing particles from zinc and lead bearing particles contained in an aqueous slurry of blast furnace dust and the recovery and reuse of the carbon and iron bearing particles as charge material in a blast furnace is described. An aqueous slurry of blast furnace flue dust is collected in a thickener. The thickened aqueous slurry is strained to remove large foreign matter and make a size separation at about 4 mm. The plus 4 mm particles are generally wasted. The aqueous slurry containing the minus 4 mm particles is fed into at least one hydrocyclone where a size separation is made at between about 3 and 5 microns. A substantial portion of the carbon and iron bearing particles report to the hydrocyclone underflow and a substantial portion of the zinc and lead bearing particles report to the hydrocyclone overflow. The carbon and iron bearing particles are passed to a preparation plant to be prepared for reuse in the blast furnace. The zinc and lead bearing particles may be passed to waste or stored for subsequent processing. Optionally, the water in the slurry may be treated with a neutralizing agent to precipitate dissolved zinc and lead values which can be removed from the water with the zinc and lead bearing particles in a hydrocyclone to thereby upgrade the water to acceptable environmental standards.