Hot metal de-sulphurisation is a dip-lance process involving the pneumatic injection of fine-grained de-sulphurisation reagents into the molten metal. For maximum efficiency the particles must be dispersed in the ladle as widely as possible to increase the total interfacial area which is primarily controlled by the lance design. Seven different lance configurations were modelled and simulated to determine the most efficient design using physical and mathematical modelling approach. A 0.25 scale plexi-glass model of the 100 T hot metal ladle was fabricated for the study. Residence time and mixing time studies were carried out using the electrical conductivity measurement technique through stimulus response of injected saturated salt solution. Mathematical modelling approach using momentum balance was used to simulate fluid flow profile of lance-ladle assembly under operating conditions using computational fluid dynamics package ANSYS-CFX. Based on the studies a new curved port lance has been designed which resulted in uniform and swirling flow profile inside the ladle without rotating the lance. Injection through the new lance increased the residence time of the particles and reduced the dead zones. The new design was fabricated and experimented at de-sulphurisation stations and has resulted in reduced flux consumption and treatment time.

Generation of high iron containing wastes such as mill scale, dust and sludge are inevitable in steel making process. It is important to develop and implement processes to recycle and re-use these wastes. An attractive option is to recycle these wastes through BOF steel making process, but is not suitable for handling and efficient operation in available forms. Present work shows the briquetting of steel making wastes using various binders in a pilot scale briquetting machine. In briquetting tests, the effecting parameters have been studied for determining the best combination of binders and operating parameters. A process for briquetting mill scale in optimum combination with CRM dust and BOF dusts using an organic binder has been established. Separate indices were formulated as acceptance criterion for use of mill scale briquettes in BOF service conditions involving dynamic, crushing, abrasive and thermal loads. Subsequently, series of trials were conducted with use of mill scale briquettes as secondary coolant replacing iron ore in 130T LD converter. The present paper compares the effect of mill scale briquettes vis-à-vis iron ore on process parameters in BOF steel making and also highlights its operational advantages.

The scarcity of good quality coking coal for the blast furnace (BF) has made steel makers look for an alternative iron-making process that requires little or no coke. The Corex process has been developed as an alternative to BF iron-making, which uses non-coking coal and a small amount of coke as fuel, and pellet/lump ore as iron-bearing feed. JSW Steel operates two Corex units each of 0?8 Mtpa, commissioned in 1998 and 2001 respectively. Iron oxides and non-coking coals have to meet certain physical, chemical and high temperature properties for stable operation and to attain high performance levels. Experience of the Corex operation with various coals and iron oxides over the years has helped in understanding the influence and sensitivity of raw materials on its performance and develop new raw material specifications. Statistical analysis of plant data showed that the significant parameters affecting fuel rate and production are moisture, volatile matter, char strength after reaction of coal, reduction disintegration index (RDI; %, -6?3 mm) of pellets and slag rate. This helped achieve the most efficient operating parameters, surpass rated capacity and utilise steel plant waste. The present paper brings out the impact of various raw material properties, and the modified specifications of coal and iron oxides for Corex.

Gas distribution control under high pellet blast furnace (BF) burden operation is more difficult than with sinter due to low angle of repose, high rolling characteristics and layer collapse tendency. Also heavier pellets exert a pushing effect on the preceding coke layer thereby forcing coke towards wall with the pellets also rolling down towards the centre. High pellet proportion at the centre promotes high peripheral flow affecting the burden layer profile and process stability. In order to achieve accurate gas distribution, changes in batch sequence discharge at the stock house and material discharge rate inside the furnace were altered. To avoid excessive rolling of pellets inside the furnace, ore and coke falling trajectory was monitored and optimised to enhance central gas flow without centre coke charging. With a high pellet content of up to 70-80%, BF-1 productivity up to 2?1 t m 23 per day and fuel rate down to 570 kg/tonne of hot metal was achieved.

Corex is an alternative smelting reduction ironmaking process where non-coking coal and pure oxygen is used instead of coke and air. The temperature of the tuyere region is much higher than in a blast furnace, and sustainability of tuyeres is a major challenge. At JSW Steel Ltd, almost 15% of the total shutdown is due to burnt tuyere replacement. A detailed analysis of tuyere failure and process parameters effecting tuyere burning was conducted to understand the failure mechanism and the root causes. A common reason does not exist for all types of tuyere failure; however, the collective reasons for failure are excessive coal fines (26?3 mm) and small mean particle size, low back pressure, blocking of tuyeres, scab formation and slip.