Process for the Preparation of Basic Copper Carbonate


The invention relates to a process for the preparation […]

The invention relates to a process for the preparation of Basic Copper Carbonate by reacting copper salts with alkali carbonate in aqueous solution at elevated temperatures and with stirring and subsequently isolating the copper carbonate. In this process, a waste solution from copper etching processes which contains hydrochloric acid and sodium chloride, is stirred into a 5 to 15 weight percent solution of alkali carbonate heated to 40° to 70° C., the pH of the solution not being allowed to fall below 6.5, and the precipitated basic copper carbonate is separated from the aqueous solution in a known manner. A light green, basic copper carbonate is obtained, which is free of copper chloride and copper oxide.

Large amounts of waste solutions from copper etching processes are obtained in the production of etched moldings and printed circuits. There is a need to recover the copper from these solutions in the form of economically valuable copper salts, such as, for example, copper carbonate, and to utilize these salts in a meaningful manner. In this connection, it has proven to be particularly difficult to work up waste solutions from copper etching processes which contain hydrochloric acid.

The process for the preparation of agglomerates of bismuth-containing crystalline particles from basic copper carbonate. It mentions, however, a process for the preparation of basic copper carbonate, in which hydrated copper carbonate is precipitated by simultaneously feeding in the copper salt solution and the neutralizing alkali carbonate while stirring and maintaining the pH between 5 and 8. In a second step, the reaction mixture is converted at temperatures of at least 60° C. into basic copper carbonate. Apart from the fact that very pure copper salt solutions are used in this process, the purpose of the process is to prepare a crystalline, bismuth-containing copper carbonate for use in the preparation of a copper(I) acetylide complex that can be used as a catalyst. From a chemical engineering standpoint, controlling the simultaneous feeding of reactants is very expensive.