NEUTRALIZATION OF ACID WATER IN THE CHEMICAL-INDUSTRY WITH LIMESTONE

The replacement of lime with limestone for the neutralisation of acid water was investigated through batch and semi-continuous studies. A fl uidised-bed reactor with multiple stages of increasing diameters is pr eferred for the limestone neutralisation process as it allows fluidisa tion of the bigger particles but also prevents washout of the smaller particles in the case where ungraded particle size limestone is used. It was determined that the rate of neutralisation is influenced by the particle size of limestone and the type of metal in solution. Sulphat e is removed as gypsum to the level where the water is saturated with calcium sulphate, while CO2 is produced as a by-product.