Abstract: The invention refers to a method for recovering copper from waste fishing nets. The method of the invention includes washing of nets in a washing liquid, wherein an antifouling coating and other impurities are removed from the surface of the nets to a largest extent possible. The washing liquid is water; NaOH can also be added into the water in order to improve the efficiency of washing, such that the NaOH concentration in the water is up to 20%. The suspension of the washing liquid, sludge and other impurities, resulting from the washing step, is led to a separation step. The sludge obtained in the separation step is led to the dissolution step in an acidic medium. A strong mineral acid is selected as the acidic medium, such as H2SO4, HNO3, HCl, a mixture of strong mineral acids or a mixture of one or several strong mineral acids with H2O2.

Abstract: A method of locally repairing parts coated with a thermal barrier including a ceramic outer layer and a metal underlayer of alumina-forming alloy for protecting the substrate against oxidation and for bonding with the ceramic outer layer, includes: defining the zone for repair with a mechanical mask adapted to the shape of the part and the zone for repair; scouring the zone for repair so as to remove the ceramic, the alumina layer, and the damaged portions of the underlayer; supplying materials for repairing the underlayer to the repair zone by subjecting the partially-scoured part to metal deposition by use of an electrical current; and subjecting the part to a heat treatment in order to enable the added metals to diffuse into the remaining underlayer in the repair zone for repair and to enable a surface film of alumina to form. After the underlayer has been reconstituted, the zone for repair is again defined by a mechanical mask and a new ceramic layer is deposited thereon.

Abstract: The present invention relates to a process for preparing a zinc dithionite solution wherein the process comprises reacting an aqueous slurry of zinc particles with sulfur dioxide in presence of a promoter compound. The zinc particles can either be a commercial particulate zinc material or a particulate zinc material prepared by electrolyzing an aqueous alkaline suspension or slurry containing zinc based species. The addition of the promoter compound significantly increases the conversion of zinc to zinc dithionite and significantly reduces the cycle time of the reaction. The promoter compound is selected from the group consisting of sodium hydroxide and metal compounds. The promoter metal compounds are selected from the group consisting of an alkali metal hydroxide, zinc oxide, zinc sulfite, zinc bisulfite, zinc metabisulfite, an alkali metal zincate, an alkali metal sulfite, an alkali metal bisulfite, and mixtures thereof.

Abstract: Disclosed is a process for preparing zinc dithionite comprising reacting zinc metal with sulfur dioxide, wherein the zinc metal used in the reaction is produced by electrochemical reduction in an undivided electrochemical cell of an aqueous alkaline slurry or solution of zinc oxide or any other zinc compound that reacts with aqueous base to form zinc oxide.

Abstract: A process for the simultaneous preparation of sodium peroxodisulfate and sodium dithionite in an electrolysis cell divided into two by a cation exchanger membrane, wherein sodium dithionite is produced at the cathode and sodium peroxodisulfate is produced at the anode.

Abstract: A process for producing sodium gold sulfite in solution is described. The sodium gold sulfite solution is useful in gold electroplating baths, and can be used in applications which require pure, soft gold deposits. A process is also described whereby the sodium gold sulfite solution can be solidified by a freeze-drying process.