Blast furnace hearth overloading and the methods of its cleaning

The analysis of the methods of control of the state of the useful capacity of blast furnace hearth was carried out, the rational technology of flushing the periphery and the entire hearth volume under operation conditions of blast furnaces with supply of coal powder fuel was developed. The diagnostic techniques of the state of the useful capacity of blast furnace hearth were analyzed, methods of determination of presence of hearth overloading were proposed, the signs of solid hearth overloading, requiring application of special measures of its cleaning were found out. As a rule, blast furnaces, including their hearths are flushed by charging some special flushing materials into blast furnaces. These flushing methods require additional calculations for flux consumption, coke mass into the charge, estimated cast iron chemical composition et al. Theoretical fundamentals of the possibility of flushing of the periphery of hearth without charging of flushing materials, by reducing consumption of oxygen blast for oxidizing hydrocarbonaceous additions were developed. The work also contains a critical analysis of application of the methods of flushing of the periphery and the entire volume of blast furnace hearths and a rational method of carrying out these operations was proposed that does not alter an even run of a blast furnace and does not presume charging of any flushing materials into the furnace. This method is quite vital for operational conditions of blast furnace shops of iron and steel works of Ukraine, that face shortage of flushing materials of domestic production. The efficiency of application of the existing and proposed methods of flushing blast furnace hearths was estimated. For operation conditions of iron and steel works of Ukraine the method of hearth periphery flushing, based on alternation of the amount of coal powder fuel which is blown into the furnace during the period of discharge of liquid smelting products seems to be more rational.