METHOD AND APPARATUS FOR ELECTROWINNING COPPER USING THE FERROUS/FERRIC ANODE REACTION AND A FLOW-THROUGH ANODE
The present invention relates, generally, to a method and apparatus for electrowinning metals, and more particularly to a method and apparatus for copper electrowinning using the ferrous/ferric anode reaction and a flow-through anode, such as, for example, a dimensionally stable carbon, carbon composite, metal-graphite, or stainless steel anode. In general, the use of a flow-through anode—coupled with an effective electrolyte circulation system—enables the efficient and cost-effective operation of a copper electrowinning system employing the ferrous/ferric anode reaction at a total cell voltage of less than about 1.5 V and at current densities of greater than about 26 Amps per square foot (about 280 A/m2), and reduces acid mist generation. Furthermore, the use of such a system permits the use of low ferrous iron concentrations and optimized electrolyte flow rates as compared to prior art systems while producing high quality, commercially saleable product (i.e., LME Grade A copper cathode or equivalent), which is advantageous.
1 . A method of electrowinning copper comprising:
providing an electrochemical cell comprising at least one flow-through anode and at least one cathode, wherein said cathode has an active surface area;
providing a flow of electrolyte through said electrochemical cell, said electrolyte comprising copper and solubilized ferrous iron;
oxidizing at least a portion of said solubilized ferrous iron in said electrolyte at the at least one flow-through anode from ferrous iron to ferric iron, wherein the at least one flow-through anode comprises at least one of a carbon foam, a graphite foam, a metal-graphite sintered material, a polycrystalline graphite, a graphitizable pitch material coated with polycrystalline graphite, a graphitizable pitch material densified with polycrystalline graphite, a graphitizable pitch material coated with graphite foam, a graphitizable pitch material densified with graphite foam, a fiber reinforced carbon-carbon composite, a fiber reinforced carbon-carbon composite having graphitizable particulates, a graphite coated metal mesh, and a carbon coated metal mesh; and
removing at least a portion of said copper from said electrolyte at the at least one cathode; and
operating said electrochemical cell at a cell voltage and at a current density, wherein said cell voltage is less than about 1.5 Volts and wherein said current density is greater than about 26 amperes per square foot of active cathode.
2 . A system for electrowinning copper from a copper-containing electrolyte, comprising:
an electrolyte stream, wherein said electrolyte stream comprises copper and solubilized ferrous iron; and
an electrochemical cell, wherein said electrochemical cell comprises at least one flow-through anode, at least one cathode, and an electrolyte flow manifold, wherein said at least one flow-through anode comprises at least one of a carbon foam, a graphite foam, a metal-graphite sintered material, a polycrystalline graphite, a graphitizable pitch material coated with polycrystalline graphite, a graphitizable pitch material densified with polycrystalline graphite, a graphitizable pitch material coated with graphite foam, a graphitizable pitch material densified with graphite foam, a fiber reinforced carbon-carbon composite, a fiber reinforced carbon-carbon composite having graphitizable particulates, a graphite coated metal mesh, and a carbon coated metal mesh.