CAS-OB Process of Secondary Steelmaking Oct03

CAS-OB Process of Secondary Steelmaking...

CAS-OB Process of Secondary Steelmaking The CAS-OB process consists of Composition Adjustment by Sealed argon bubbling with Oxygen Blowing. It was developed by Nippon Steel Corporation. Typical schematic diagram of a CAS-OB installation is shown in Fig 1. Fig 1 Schematic diagram of a CAS-OB installation The process allows alloy additions to be made under an inert argon environment. It allows simultaneous addition of Al and O2 gas blown through a top lance. These react to form Al2O3 and generate a considerable amount of heat due to exothermic nature of the reaction. The CAS-OB process, therefore results into chemical heating of the liquid steel. The Equipment Liquid steel processing is carried out in ladles, equipped with slide gates and a porous plug for blowing argon. Equipment for the process consists of a snorkel or bell fixed to the movable bracket. To the top of the bell, a port is provided, which serves the purpose of feeding of ferro alloys into the bell and for removal of gases to the gas cleaning system. The design of the bell has provision for lowering of oxygen lance and process and instrument (PI) lance for sampling, measuring of the temperature and for measuring of the dissolved oxygen as well as a lance for injecting a metal powder, desulphurizing compound and CaSi wire. Bell consists of two parts. The upper part is lined only from the inside, while bottom is lined both inside and outside. Lining of the bell is usually done with of high-alumina castables reinforced with 2 % stainless steel needles. These castables are also used for the lining of the oxygen lance and lance for blowing argon into the liquid steel, which is used when argon cannot be supplied to the liquid steel through the bottom porous plug. Chrome magnesite bricks...