Salt cake processing method and apparatus
AssigneeAlumax Mill Products, Inc.
InventorsPandelis N. Papafingos, Richard T. Lance
Life of this patent
Estimating the term…
Abstract
A method of recovering aluminum metal values and salt cake and recycling or reusing the same in an aluminum refining method is disclosed.
Claims11
The improved method of recovering metallic values from dross and recovering fluxing salts used in the recovery of such metallic values comprising the steps of:
- Step 1:
- removing dross from the melt and cooling the dross to retain in the dross metallic aluminum entrained therein;
- Step 2:
- heating the dross under a cover of flux salts comprised of chloride salts of metals selected from the group consisting of alkali, alkaline earth metals and mixtures of the same to a temperature above the melting point of aluminum;
- Step 3:
- removing molten aluminum from the dross leaving a flux-dross mixture having entrained therein residual aluminum metal;
- Step 4:
- cooling the flux-dross mixture to form a salt cake product comprising pieces of salt cake having an average size of less than about 1 inch in thickness and about 100 square inches in area;
- Step 5:
- digesting said salt cake product by heating and agitating the same in water to thereby dissolve the salt therein to form a brine slurry of the salt in solution and the insoluble constituents of the dross;
- Step 6:
- separating the brine slurry into at least one cut consisting substantially of larger chucks of metal and dross having an average minor diameter of greater than about 250 microns and a final cut consisting essentially of a slurry of brine and particles having an average minor diameter of less than about 700 microns;
- Step 7:
- separating from the slurry of Step 6 substantially all particles of dross and washing the same to produce a by-product consisting essentially of particles of aluminum oxide and aluminum metal having an average particle size of less than about 700 microns;
- Step 8:
- evaporating a portion of the brine remaining after the separation of Step 7 to thereby cause crystallization of a portion of the salt dissolved therein and form a salt crystal-brine slurry and
- Step 9:
- separating crystallized salt from the crystal-brine slurry of Step 8 to produce a flux salt product suitable for recycling as part of the flux salts of Step 2 and returning the brine remaining from the separation for further evaporation in Step 8.
In a process for treating aluminum dross wherein metal containing dross is heated under flux salt to melt and remove the metallic constituents, the improvement comprising the steps of:
- First, digesting the residual mixture of flux salt and dross by heating and agitating the same in water to dissolve the flux salt thus forming a slurry of dross particles in brine;
- Second, separating the dross particles from the brine;
- and
- Third, concentrating the brine and causing precipitation of flux salt crystals by repeatedly contacting thin layers of the brine on an evaporator surface with hot, flowing gas to cause formation of salt crystals on said surface and repeatedly immersing said surface into the brine to thereby wash said surface free of crystals and re-form a layer of brine thereon.
The process of preparing salt cake for digestion comprising casting molten, slat-like flux salt-dross mixture onto a rotating surface and, by such rotation, causing the salt-dross mixture to spread into thin layers and to break into pieces to form a salt-dross product composed of generally flat pieces less than about 1 inch in thickness and less than about 100 square inches in surface area measured on the largest generally flat surface thereof.
Dependencies are inferred from the claim text.