Integrated treatment of GCP and slag quenching water of LD steel making unit

The scarcity of water has driven every steel plant in India to pursue major water conservation initiatives. R&D Tata Steel Jamshedpur has invented an integrated and cost effective process for treatment and reuse of steel making gas cleaning plant (GCP) wastewater and Linz-Donawitz (LD) slag quenching (SQ) wastewater. The new treatment process consists of mixing of GCP water with SQ wastewater in a specific ratio followed by coagulant addition and controlled carbon dioxide (CO2) sparging. The average total suspended solid (TSS) and total dissolve solids (TDS) concentration of treated water were observed to be 22 and 190 mg L-1 during 180 days of continuous monitoring. Thus the water quality falls well within the limits for reuse and recycle standards within the plants. The maximum allowable limit of TDS and TSS for industrial water supplies is 500 and 100 ppm, respectively. The process significantly reduces the water requirement for steel making and paves the path for conversion of LD steel making process into a sustainable 'Zero Liquid Discharge' unit.