Low Grade Refining
Sweeps require more involved processing than clean scrap. Because of its large volume and low grade content, melting sweeps would not be practical. Sweeps need to burn at low heat, to incinerate the combustible material. It is then pulverized, sifted, and milled into a fine powder. By blending this fine powder, the sweeps is made homogeneous. An accurate sample is then taken and assayed to determine the exact amount of precious metal content.