Degree Type


Date of Award


Degree Name

Doctor of Philosophy


Chemical and Biological Engineering


A novel 2 stage process for the separation and recovery of the Cu, Fe and S from chalcopyrite (CuFeS(,2)) was investigated. In stage 1, CuFeS(,2) particles are reduced in the catholyte chamber of a fluidized bed electrochemical reactor (FBER). A digenite (Cu(,1.8)S) product layer forms on the unreacted CuFeS(,2) and Fe(II) dissolves into the catholyte solution. All the Cu remains in the solid phase. In stage 2, the chalcopyrite reduction product layer from stage 1 is oxidized in an electrolyte different from that used in stage 1. The final products of stage 2 are Cu (I), Cu (II) and S('o). The overall process dissolves and separates the Cu and Fe in CuFeS(,2) into a Fe rich electrolyte and a Cu rich electrolyte. The S in CuFeS(,2) reacts to form H(,2)S and S('o);A model was developed to explain the results of the chalcopyrite reduction experiments. The model was based on the assumptions that (i) the rate of chalcopyrite reduction is controlled by the concentration of H('+) at the reacting surface/electrolyte intercase and (ii) the concentration of H('+) at the interface is controlled by the diffusion of H('+) through the porous chalcopyrite reduction product layer. The model is in general agreement with the experimental results;The production of Cu (I) during the dissolution of the chalcopyrite reduction product layer was found to occur only when using a 4 M HCl anolyte. The amount of Cu (I) that was produced fell sharply when the total cell current exceeded 19.5 amperes. Complete oxidation of the copper sulfide layer was easily accomplished;Oxidation of the chalcopyrite reduction product layer was possible in 4 M HClO(,4), 2 M H(,2)SO(,4) and 2.7 M H(,3)PO(,4), except that Cu (II) was the only dissolution product and dissolution of the copper sulfide was replaced by O(,2) evolution when the solid phase stoichiometry reached CuS. Addition of Cl('-) to the electrolyte prevented the production of O(,2) and caused the CuS to react, forming Cu (II) and S('o). The presence of Cl('-) also caused the evolution Cl(,2);Using auger electron spectroscopy the chalcopyrite reduction product layer that was produced in 4 M HCl was identified as Cu(,1.8)S. The rate of chalcopyrite reduction was severely limited by the thickness of the Cu(,1.8)S product layer. Removal of the chalcopyrite reduction product layer using an ultrasonic bath showed that a product layer material containing up to 15 times more Cu than Fe could be recovered.



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David Lloyd Felker



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123 pages