While sustainability has become a catchword in the global iron and steel industry, manufacturers face a two-pronged challenge of ensuring continued supply of high quality raw materials and reducing their carbon footprints. One manufacturer in Odisha (eastern state of India) faced rising costs for iron ore and coke, the primary burden materials for his BFs. However, he had a few distinct advantages like access to fines from his 3 x 50 tonne/per day sponge iron (DRI) kilns as well as BF dust, which is a rich source of iron containing about 35% to 40% iron and about 20% unburnt carbon.
Propelled by the objective of utilization of steel mill wastes the company, Suraj Products Limited, started using BF flue dust as a rich source of iron and energy and was granted a patent for the same. The sustainability solution was simple: Collecting and converting the significant quantities of sludge, dust and residues being generated as waste by the integrated steel mill and smelters. The objective all through was to transform these solid wastes from one form to another to be reused either by the same production unit or by different industrial installations, which is essential not only for conserving mineral resources but also for protecting the environment.
Waste as feed-stock
Data put out by the company show that 1000 kg of BF flue dust contains 300 kg of iron and 200 kg of carbon, whereas 1000 kg of LD sludge contains about 500 kg of iron. The company very wisely chose to manufacture cold briquettes from this waste. The stiff extrusion technique offered a scalable agglomeration process to convert mill by-products to feedstock.
Briquettes are made by the stiff extrusion process from metallurgical waste with the addition of Portland cement as a binder. The briquettes show a better mechanical strength fired at a different temperature to take the load of burden and better reducibility than lumpy iron ore.
Cold Briquettes can substitute sinter and pellets
Cold briquettes are a substitute for sinter and pellets. Both sintering and pelletizing are GHG-emitting processes. As no heating process is required, the use of briquettes leads to reduction in emissions. The process utilizes wastes thereby reducing the burden of solid waste dumping. In addition, as the cold briquetting process doesn’t require heating, there is no requirement for fuels such as coke and coal. Data published by Suraj Products Limited reveal that electricity consumption of the cold briquetting process is 10 to 15 kW per tonne, which compares more than favorably with 23 to 48.7 kW per tonne in sintering and 29 to 48.5 kW per tonne in pelletizing. Therefore, the all-important aim of energy efficiency is achieved in one single stroke.
More at SteelVia
Mr Yogesh Dalmia, MD, Suraj Products Ltd,India, will be sharing his experience and know how on this technology. Make sure you attend SteelVia – the global steel innovations forum – where leading experts will dwell on these promising technologies in detail.