Patent ID: 8211207

Claim:
A process for refining lead bullion to separate lead from impurities including amphoteric p-block elements, copper, sulfur, selenium, and tellurium, the process 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, the Lewis acid being added in stoichiometric amounts to the amounts of lighter amphoteric elements to be preferentially removed 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 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 bullion.