Iron feedstock conversion system with improved efficiency

In an iron conversion system comprising an acid regeneration cell, an impurity removal vessel, and an iron electroplating cell that is separate from the acid regeneration cell, a method comprising:

• electroplating metallic iron from an electrolyte solution containing ferrous iron ions and less than 0.1 mol/l ferric iron ions and less than 0.01 mol/l aluminum ions;
• determining that the ferrous iron ion concentration has dropped to a pre-determined low-end ferrous concentration;
• concentrating the electrolyte by removing water until the ferrous iron ion concentration rises to a pre-determined high-end ferrous concentration;
• and
• electroplating metallic iron from the concentrated electrolyte.

In an iron conversion system comprising an acid regeneration cell, an impurity removal vessel, and an iron electroplating cell that is separate from the acid regeneration cell, a method comprising:

• in a purifying plating cell, first electroplating metallic iron from an electrolyte solution containing ferrous iron ions and more than 0.01 mol/l aluminum ions;
• to form a purified electrolyte and a lower-purity iron product;
• collecting a precipitate containing at least one aluminum compound from the purifying plating cell;
• and
• after said first electroplating, directing the purified electrolyte into a product plating cell and electroplating a higher-purity iron product.

In an iron conversion system comprising an acid regeneration cell and an iron electroplating cell that is separate from the acid regeneration cell, a method comprising:

• crystallizing ferrous sulfate from a first electrolyte solution exiting the acid regeneration solution;
• dissolving the ferrous sulfate crystals in a second electrolyte solution;
• and
• electroplating metallic iron from the second electrolyte solution in the electroplating cell.