Methods for recycling electric arc furnace dust

A method for the separation and recovery of metals selected from the group consisting of iron, cadmium, zinc, and lead, from raw material comprising a mixture of iron, cadmium, zinc and lead, said method comprising the steps of:

• A. heating said raw material in the presence of carbon and an additive selected from the group consisting of limestone, silica, calcium chloride, and sulfates, to a temperature sufficient to substantially reduce and vaporize cadmium, zinc, and lead without substantially vaporizing iron,
• thereby producing vapors containing cadmium, zinc, and lead, and an iron-containing-residual sinter mass;
• B. contacting said vapors produced in Step (A) with preheated air to produce dust containing oxidized cadmium, zinc, and lead, and then separating said dust from said iron-containing-residual sinter mass by collecting said dust in a receptacle;
• C. slurrying said dust in an aqueous solution of ammonia ammonium carbonate to produce substantially insoluble lead-containing-precipitates and a zinc/cadmium bearing leach liquor;
• D. separating said zinc/cadmium bearing leach liquor from said substantially insoluble lead-containing-precipitates by filtration;
• E. adding metallic zinc to the zinc/cadmium bearing leach liquor to produce a cadmium-containing-cement;
• F. separating said cement from said leach liquor;
• and
• G. removing ammonia from said leach liquor to precipitate basic zinc carbonate.