Removal of phosphorus from LD slag using a heterotrophic bacteria

Abstract

Linz-Donawitz (LD) slag is a byproduct of the steelmaking industry and contains about 30% Ca, 20% Fe, 5% Mg and 1.4% P. For its application as flux in steelmaking, the phosphorus content has to be minimized. Bio-dephosphorization of the LD slag was attempted using bacterium Frateuria aurentia to remove insoluble phosphorus. In 13 and 30 days of leaching under appropriate conditions, about 72% and 90%, respectively, of the phosphorus could be leached from the LD slag in the presence of the bacteria at 20% pulp density. The amount of carbon source seems to be important for phosphorus solubilization by bacteria. This is a novel method for dephosphorization of LD slag and subsequent waste utilization. The dephosphorized slag can thus have application as a fluxing material in iron and steel production.