Abstract

In this paper, the pilot plant trials of a process to treat chrome shavings to isolate protein products and purified chromium are presented. The process uses two enzymes, pepsin and alkaline protease, in two consecutive extractions with the isolation of a high quality gelatin and a hydrolysate. Chrome shavings (10kg) are pretreated with 0.1% pepsin at pH 3—3.5 and at room temperature for 8 hours and gelatin is then extracted at pH 8 and 70CC; hydrolysed protein is then isolated with 0.005% alkaline protease at pH 8 and 70°C for 3 hours. The remaining solid, called chrome cake, is chemically treated to prepare it for recycling in the tanning industry. The chemical and physical properties of the protein products and the chemical characteristics of the purified chromium are presented.