Patent ID: 8500845

Claim:
A process for refining lead bullion to separate lead from impurities including amphoteric p-block elements, copper, sulfur, selenium, and tellurium, including: maintaining lead bullion at a temperature just above its melting point; removing copper from the bullion, heating the lead bullion to a processing temperature in the range of 750° F. to 850° F.; maintaining the lead bullion at the processing temperature, adding a Lewis acid component and an Arrhenius base compound to the molten lead bullion in stoichiometric amounts to preferentially remove lighter amphoteric elements from the molten lead bullion, to promote reactions with amphoteric p-block elements in the lead bullion to form over the lead bullion a slag of Lewis bases, thereby forming a slag layer incorporating the metal salts of the amphoteric p-block elements; and periodically removing at least a majority of the slag layer from the top of the lead.