Smelting-Reduction Processes

The purpose of this process was to find processes which produce liquid iron economically using directly coal. These processes are started since 1970 are new and perhaps for future could be relevant. The processes should be more flexible regarding raw material and operation and should cause less pollution than a blast furnace .By this process the ore is prereduced with the gas and melted in vessel, where melting energy is produced by oxidation of coal. Some process use also electrical energy in the melting stage.There are many method was developed to produce iron by Smelting-Reduction Processes.

This method can generally classify in the following category:

• Char-coke-bed Melter-Gasifiers:

In these processes the melting stage is a fixed bed or fluidized bed of char or coke preproduction is performed in a shaft furnace Corex , Sumitomo or fluidized bed (Kawasaki). Corex process is the most popular method of Smelting-Reduction processes in Iron industries, therefor it is separately described.

• Converter – Type Melters:

The converter- type melters was developed base from the experience of the LD (BOF) converter. Coal is injected with or without oxygen in the molten iron bath. In most of the process CO and H2 gases coming out of the melt practically combusted (post-combusted) to generate heat (up to 1900 oC ).There are several converter types used for production iron such as HIsmelt ,NSC,NKK and Coin process. The most advanced converter process is the HIsmelt process was developed by a joint venture Rio- tinto and Midrex .The Development stage should be in 10 t/d. Coal is injected from the bottom into the melt.

• Using electrical energy:

These processes were developed in Sweden and consist of a prereduction stage of the fine ore and a final reduction which use electrical energy. The electrical energy is employed via electric arc (Electrod) ,plasma burners (Plasmamelt) or electric resistance heating (Inred).There are several Processes using electrical energy such as plasmamelt, Inred ,Elred and Combismelt processes. The only process which has a technical application is the Plasmadust and Plasmachrome. Due to economical reason these processes can only be used for iron production in countries with cheap electricity

• Plasmamelt

This process was developed by SKF Steel Engineering Fine ore is prereducted with a reduction gas generated in the smelting reduction stage in fluidized bed. Then prereducted material is injected together with coal into shaft furnace provided energy with plasma generators. Recycled gas is used as injection gas. The final reduction and melting process will be occurred inside the shaft furnace. The produced crude iron and slag will be removed The Development stage should be in 10 t/d.