Separation of cobalt and manganese from trimellitic acid process residue by precipitating as carbonates, redissolving as halides and removing cobalt by magnetic means

A method of recovering cobalt and manganese and separating recovered cobalt from recovered manganese from residue obtained from the manufacture of trimellitic acid produced by the oxidation of liquid pseudocumene with molecular oxygen in the presence of cobalt and manganese as the metal oxidation catalyst;

• which method of recovery and separation comprises dissolving the acidic organic components of said residue in water containing carbonate ion together with sodium, or potassium, or ammonium ions and precipitating catalyst metals as carbonates;
• separating the aqueous solution from the metal carbonate precipitate;
• redissolving the catalyst metals as their halides by mixing the carbonate precipitate with an aqueous solution containing hydrochloric or hydrobromic acid in an amount to provide a solution pH of 3 to 4 thereby precipitating iron, if present,;
• thereafter adjusting the precipitate-free solution's pH to 5 to 6 and adding powdered manganese thereto in an amount of from 1 to 2 chemical equivalents for each 1.0 chemical equivalent of cobalt in solution thereby precipitating metallic cobalt;
• and magnetically separating the pH-adjusted solution from the metallic cobalt precipitate.