The Process of Blowing-in of a Blast Furnace Apr29

The Process of Blowing-in of a Blast Furnace...

The Process of Blowing-in of a Blast Furnace  The process of starting a blast furnace after its construction or after its relining is called blowing-in. The blowing-in process is carried out in several steps (Fig 1) which consist of (i) drying out the lining, (ii) filling of the blast furnace with a specially arranged high coke blow-in furnace charge, (iii) igniting of the coke or lighting of the blast furnace, and (iv) gradually increasing the hot blast (wind rate) with frequent castings to ensure the raising of temperature of the blast furnace hearth. During the period of blow-in, the burden ratio (ratio of the ore to coke) is adjusted according to a predetermined schedule until the normal operation of the blast furnace is achieved and the blast furnace starts producing the normal  quality of the hot metal. Fig 1 Steps in the blowing-in process of a blast furnace  Newly constructed or relined blast furnace is to be carefully dried before the coke is ignited. It is  because the large amount of water contained in the slurry used for refractory brick laying and the water absorbed by the refractory brick work is to be driven off as much as possible for avoiding  extreme thermal shock. There is sufficient data available that blowing-in of a blast furnace can cause damage to the refractory lining even when it has been properly dried. Furthermore, if the water from these sources is not removed from the blast furnace before it is put into operation, it absorbs heat more than that provided for the blow-in charge and hence prevents the hearth from reaching the desired temperature. In such cases, hot metal and liquid slag entering the hearth can freeze there and in such case it becomes impossible to remove them...