Clean and efficient extraction of copper ions and deposition as metal

AbstractA simple, clean and efficient one-pot process is offered as an alternative to the conventional complex processing presently used to extract copper ions from copper containing materials, like copper concentrate or slag, and to form copper metal. The alternative process uses a eutectic molten salt of potassium chloride, sodium chloride and zinc chloride as the reaction fluid which is recyclable, low in cost, environmentally benign, low melting (melting point 204°), high boiling (vapor pressure is only a few psi at 800°) and chemically, thermally and physically stable. The metal completely dissolves out of copper concentrate or slag in the aerobic eutectic molten chloride salt in a graphite or glassy carbon pot, which serves as a cathode, with a graphite anode, to reduce the metal ions to metal which sinks to the bottom of the graphite pot. The total efficiency for extraction and deposition is virtually 100% as determined by elemental and gravimetric analyses

Corrosion and High Temperature Oxidation Behavior of 316L Stainless Steel Joined with Cu-Ag Based Braze Alloys

316L samples of various geometries were joined under Argon atmosphere using Cu-Ag based braze alloys. Following joining, elemental and phase composition across the braze and parent metal interface was characterized with optical microscopy and SEM with EDS. Baseline electrochemical testing was performed on each of the braze alloys in the fired and unfired condition. Additionally, metal-to-metal braze specimens were prepared in order to expose the braze interface to 0.6 M NaCl electrolyte where the free corrosion potential was monitored. Following exposure to the aggressive solution, the corrosion damage morphology was characterized to determine the mode of attack and likely initiation areas. The critical potential for localized corrosion initiation was also investigated for the braze alloys when connected galvanically to 316L samples to determine the impact of brazing on localized corrosion. Initial results indicate dissimilar metal driven corrosion attack at the braze metal interface into the parent 316L as well as preferential dissolution of the Cu rich phase within the braze alloy when exposed to 0.6 M NaCl