Purification of sulphuric acid at Wispeca

Abstract

The anodizing plant at Wispeco Aluminium in Alrode, Alberton, uses various chemicals, but mainly sulphuric acid, in their anodizing process. During the anodizing process aluminium and other unknown substances dissolve into the sulphuric acid. The concentration levels of the dissolved aluminium within the sulphuric acid are checked and regulated daily to ensure that the aluminium concentration does not exceed a level higher than 14g/.. At the end of each week the sulphuric acid is disposed of and replaced with new sulphuric acid. An investigation was conducted at the anodizing plant to determine the viability and effectiveness of purifying the sulphuric acid. The main goal of the project is to identify acid purification methods in order to significantly decrease the purchasing and usage of new sulphuric acid in the anodizing process. The plant was inspected to determine whether there is sufficient space for a purification system. An acid analysis was also done to determine what other unknown substances . apart from aluminium - are found in the sulphuric acid solution which then could also be removed during the purification process. The current anodizing process at the plant was analysed and discussed with the role players to gain a better understanding of the process and the current problems within the process. A literature review was conducted of articles, case studies, journals and books about anodizing and the purification of sulphuric acid. From the literature review the best purifying methods were identified and documented. A cost-analysis was done by comparing (1) the purchase- and installation costs of an acid purification system with (2) the total cost-savings if such a system were implemented. Different suppliers were contacted to obtain quotes for the purchase and installation of an acid purification system and a cost-analysis was done at the effluent plant in order to determine the cost-savings. Results were documented and recommendations were made.