Process for purifying lead using calcium/sodium filter cake

Abstract

A method for processing crude lead bullion using a reactive metal mixture intermediate by-product having sodium and calcium includes the steps of pouring molten crude lead bullion from a blast furnace into a casting vessel, cooling the crude lead bullion so that a crust forms on top thereof, punching a hole in the crust, injecting a reactive metal mixture intermediate by-product comprising sodium and calcium below the crust and into the crude lead bullion, and allowing the contents of the casting vessel to cool to form three equilibrium phases, including a bottom phase of refined lead bulletin, a speiss phase formed on top of the lead bullion phase and including Cu.sub.3 As and Fe.sub.2 As, and a matte phase formed on top of the speiss phase and including copper, sodium, calcium and sulfur. A method for processing a previously-produced lead dross containing entrained lead using a reactive metal mixture intermediate by-product includes adding molten lead to a kettle, agitating the lead, adding a reactive metal mixture intermediate by-product comprising sodium and calcium to the lead to form an alloy of lead, sodium and calcium, adding a lead dross comprisingy Cu.sub.2 S, PbS and entrained lead to the alloy, discontinuing the agitation, and allowing the alloy to equilibrate to form a matte phase including Cu.sub.2 S, Na.sub.2 S, CaS and CaO and a lead phase that included a portion of the lead that was formerly entrained and/or chemically bound in the dross.

Dependencies are inferred from the claim text.