Method for producing highB purity aluminum from aluminum chloride

A method for producing a Si—Al alloy by the electrolytic reduction of aluminum chloride, comprising:

• providing a cell comprising:
• a plurality of electrode stacks arranged in pairs, wherein each electrode stack comprises:
• an upper terminal anode;
• a lower terminal cathode;
• and
• one or more intermediate bipolar electrodes disposed between the upper terminal anode and the lower terminal cathode in a superimposed, vertically spaced relationship defining inter-electrode spaces;
• a plurality of bath supply passages extending downwardly along one side of each electrode stack, and in fluid communication with:
• (a) a bath reservoir located above the plurality of upper terminal anodes;
• (b) each inter-electrode space for that stack;
• and (c) a molten alloy product sump located below the plurality of lower terminal cathodes;
• and
• a plurality of bath return passages extending upwardly between each of the paired electrode stacks, and in fluid communication with:
• (a) each inter-electrode space for both of the paired electrode stacks;
• (b) the bath reservoir, and (c) the aluminum product sump;
• adding aluminum chloride and SiCl4 into the bath reservoir using one or more feed ports;
• controlling the electrode current density to maintain the desired circulation rate of a chloride bath within the cell;
• removing a chlorine gas stream from the bath reservoir using one or more offgas ports;
• and
• removing a molten Si—Al alloy from the molten alloy product sump using one or more tapping ports.