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A novel technique of direct copper precipitation from a loaded chelating extractant using hydrogen in an autoclave (pressure hydrogen stripping) was studied. In its simplest form, the reaction is given by / {CuL(,2)}(,org) + H(,2)(g) (--->) 2{HL}(,org) + Cu(s). / Kelex 100 (Sherex Chemical Co. - commercial solvent extraction reagent), an alkylated derivative of 8-hydroxyquinoline was used as the basis of the present investigation and represents HL in the above equation. / Two types of experiments were carried out: (a) those designed to study the chemical and thermal response of the extractant at high temperature and hydrogen pressures and (b) those which describe the chemistry and kinetics of hydrogen stripping. / The extractant was found to exhibit excellent chemical stability up to 573 K (300(DEGREES)C) and 2.76 MPa (400 psi) hydrogen in the absence of copper. Its chemical stability was somewhat reduced when loaded with copper. In the latter case, some limited hydrogenation of the quinoline nucleus of the extractant and some of the impurities present (furoquinolines) was observed. The chemical stability of the extractant was found to be enhanced when at least 0.52 M of a long-chain alcohol (decanol) was added to the organic solvent (0.4 M Kelex/kerosene). A slow thermal dissociation of the copper chelate was found to take place within the experimental temperature range studied (443 to 488 K). This resulted in copper precipitation and organic regeneration. / Copper in a powder form was found to precipitate rapidly from loaded Kelex 100/decanol/kerosene solvents by reaction with hydrogen at pressures between 0.52 and 4.00 MPa (75 and 580 psi) and temperatures from 443 to 488 K (170 to 215(DEGREES)C). The overall process has heterogeneous characteristics. Nuclei are provided through slow thermal dissociation of the copper chelate. The freshly produced metallic copper, acting autocatalytically accelerates the precipitation kinetics. Reduction of the Cu(II) chelate to Cu(I) complex appears to be the rate controlling step. / In addition to temperature and pressure, the effects of seeding, agitation, copper concentration, ligand concentration and copper chelate age were investigated. Some physical and chemical properties of the copper powder product were also determined.

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