Pilot Scale Trials for Higher Exhausting Chromium Tanning

Chromium tanning is a matter of high concern due to chromium containing effluents and wastes. More ecologic systems with less chromium usage or chrome-free production systems are subject of studies in recent years. One of the approaches in this concern is to use non-pickling systems and higher initial pH to increase exhaustion in chromium tanning. However adopting this system in leather industry has some challenges like to assure the same quality. In a project with one of the leading companies in Turkish Leather Industry, higher exhausting chromium tanning system has been planned to be tried in laboratory, pilot and industrial scales respectively with various pH and pre-tanning agent parameter changes. In the present stage (pilot scale trials) of the project, best resulting formulations from the laboratory scale trials were carried out to pilot scale (500kg batches) by expanding the trials with additional pre-tanning agents. From the results, it was seen that chromium remaining in the baths were varying between 325 - 875 mg/L. Which means amount of chromium remaining in residual baths could be reduced up to 78.87 % to 92.15% comparing to conventional tanning while 2.9-4.7% of Cr2O3 bound to the leathers depending on the type of system used in pilot scale trials.