Utilization of ferric oxide generated in the acid regeneration plant in paint making (a case study: roofings rolling mills ltd, Namanve, Kampala)

Abstract

This study investigated the utilization of ferric oxide generated in the Acid Regeneration Plant (ARP) of the steel galvanizing line as an ingredient in making paint. The waste acid liquor generated from the process of pickling the steel sheet surface with an acid to remove stains, rust and dust before galvanizing is pumped to the reactor tanks of the ARP where it is heated using oxygen and steam to very high temperatures varying between 370°C - 700°C. The by- product of the reaction in the reactor is ferric oxide that is not utilized and is openly disposed in landfills which is hazardous to human health and the environment. In this study, several experiments and observations were carried out on random samples of the ferric oxide generated from the ARP to ascertain whether its properties were close to that of the ferric oxide sold on the market so as to establish the potential use of the ferric oxide generated in the ARP in paint making. The chemical and physical properties of ferric oxide generated in the ARP were analyzed, the ferric oxide was then neutralized, and its potential utilization in paint making was demonstrated. The analysis of the ferric oxide obtained from the ARP showed presence of the chloride ion which is responsible for the acidity of the ferric oxide making it unsuitable for making paint. The ferric oxide was neutralized by mixing it with water and manganese IV oxide and the mixture heated to temperatures above 100oC until a yellowish gas was given off giving neutralized ferric oxide residue of the pH in the range of 6.98 – 7.19. The neutralized ferric oxide was used as a dye in paint and it was concluded that ferric oxide generated from the ARP can be neutralized and gainfully utilized as a dye in paint in manufacture of ferric oxide paint. This leads to attainment of a cleaner environment through reduced open disposal of ferric oxide, reduced ferric oxide disposal costs, and minimize air pollution with reduced inhalation of hazardous fumes by humans.