Decopperization process of waste solutions from conventional copper electrolysis

This paper is adresses on treatment of sulphuric acid waste solutions obtained during the conventional copper metallurgical activities. Mother liquor is a part of this solutions and it is generated during the regeneration process of copper bleed solution. Copper, nickel and sulphuric acid are the main components and the other registered impurities are: As, Se, Fe, Sb, Zn, Bi, Pb, Cl ions. Aim to copper removing from the mother liquor, the decopperization process on the industrial scale equipment, is investigated. Investigation was done using the rectangular insoluble lead anodes alloyed with 6 wt.% of antimony at current value of 13 000 A, identical to the current in a commercial copper refinery plant. A few parameters as so as: current, cell voltage, electrolyte temperature, electrolyte flow rate, level of electrolyte, were monitored during the test. Comparing the values of copper content in the solution before and after the decopperization of copper, it was found that it decreased of about 80 wt. % of the initial value. Chemical characterization of the sludge obtained on cathode has shown that it is a material with copper content of about 90 wt. %

Leach-SX-EW copper revalorization from overburden of abandoned copper mine Cerovo, Eastern Serbia

Hydrometallurgical processes for copper revalorization from overburden of abandoned mine Cerovo in Eastern Serbia were studied. Paper contain results of percolation leaching tests, performed with acidic mine waters accumulated in the bottom of the former open pit, followed by solvent extraction (SX) and electrowinning (EW) processes on achieved copper pregnant leach solutions. Usage of accumulated waste waters was objected to minimizing the environmental hazard due to uncontrolled leaking of these waters in nearby creeks and rivers. Chemical composition of acidic mine waters used for leaching tests was: (g/dm3): Cu - 0.201; Fe - 0.095; Mn - 0.041; Zn - 0.026; Ni - 0.0004; pH value - 3.3. Copper content in overburden sample used for leaching tests was 0.21% from which 64% were oxide copper minerals. In scope of leaching tests were examined influence of leaching solution pH values and iron (III) concentration on copper recovery. It was established that for 120 hours of leaching on pH=1.5 without oxidant agents, copper concentration in pregnant leach solutions enriched up to 1.08g/dm3 which was enough for copper extraction from solution with SX-EW treatment. As extraction reagent in SX circuit was used LIX-984N in a kerosene diluent. Cathode current density in electrowinning cell was 220Am-2 while electrolyte temperature was kept on 50±2oC. Produced cathode copper at the end of SX-EW process has purity of 99.95% Cu

Design and characterization of alcalase-chitosan conjugates as potential biocatalysts

In this study, alcalase (protease from Bacillus licheniformis) immobilization by adsorption, enzyme crosslinking and covalent enzyme binding to activated chitosan microbeads were examined. The biocatalysts highest activity was obtained by covalent immobilization of alcalase onto a solid support. The alcalase covalent immobilization onto different types of chitosan beads obtained by inverse emulsion technique and electrostatic extrusion was studied. Parameters examined under different conditions were beads diameter, enzyme loading, enzyme capacity yield, and biocatalyst activity. The highest activity and enzyme loading of 23.6 IU/mg protein and 340.2 mg/g, respectively, were achieved by the enzyme immobilized onto chitosan microbeads obtained by the electrostatic extrusion technique. FT-IR analysis was used to confirm formation of alcalase-chitosan conjugates. The activity of optimally produced alcalase-chitosan microbeads was then verified in the industrially feasible reaction systems of egg white and soy protein hydrolysis. The high degree of hydrolysis of 29.85 +/- 0.967% after 180 min and five successive reuses obtained under real conditions (50 A degrees C, pH 8) verified the covalently bound alcalase to chitosan beads a promising candidate for use in industrial egg white protein hydrolysis process