Abstract: Methods and apparatus for the hydrometallurgical separation and recovery of biological nutrients, cadmium, lead, and gypsum from raw materials such as electric arc furnace flue dust. Biological nutrients, including zinc and iron, are selectively separated and recovered from raw materials, including metals and metal oxides, and are selectively and variably recombined, to achieve a biological nutrient product which a desired relative concentration of zinc and iron. The process is a closed system generating no solid waste, no liquid water or acid waste streams, and whereby gypsum, and substantially all hazardous wastes such as lead and cadmium, are separated and recovered from raw material for sale as commercial products.