Handling of Hot Metal in Blast Furnace Iron Making Feb10

Handling of Hot Metal in Blast Furnace Iron Making...

Handling of Hot Metal in Blast Furnace Iron Making  Hot metal (HM) is produced by the reduction of descending ore burden by the ascending reducing gases in a blast furnace (BF). It is liquid in nature and gets collected in the hearth of the BF. From the hearth, the HM is tapped from the taphole of the BF after an interval of time. Normally in large BFs, HM tapping rates of 7 ton/min and liquid tapping velocities of 5 m/sec, in tap holes of 70 mm diameter and 3.5 m long, are typically encountered. The tapping rate of HM is strongly influenced by the taphole condition and taphole length. Generally the temperature of tapped HM varies in the range of 1420 deg C to 1480 deg C. The tapped HM is handled in the following three stages. Handling of the HM in the cast house i.e. from taphole to the hot metal ladles HM ladles and their transport Processing of HM either in the pig casting machine (PCM) for the production of pig iron (PI) or in the steel melting shop for making steel. Historical development of hot metal handling During the seventeenth century, the produced liquid iron (usually around 450 kg per cast) from the iron making furnace was drawn into a single trench or ladled into sand moulds to produce domestic products such as pots, pans, stove plates etc.  As the BF production increased due to many design improvements, removal of liquid products (iron and slag) became an issue. Production of charcoal BF had increased over the period from one ton to 25 tons per day. This higher tonnage could not be handled with two casts per day through a single trench in front of the tap hole. The cast house contained...

Granulation of Liquid Iron Oct15

Granulation of Liquid Iron...

Granulation of Liquid Iron Granulation of liquid iron is a method of handling of excess production of hot metal in a blast furnace (BF)  which cannot be consumed by steel making in the steel melting shop of an integrated iron and steel plant. It is a cost effective method of producing a solid product which is known as granulated iron (GI). GI has good chemical and physical properties like pig iron and can be used as a prime raw material for the purpose of steel making. GI has a chemical composition identical to the liquid iron which is being granulated. There is no oxidation or slag entrapment in the GI and there is high metallic content. Fig 1 shows some pieces of GI. Fig 1 Granulated iron  A GI plant takes care of any mismatch between the production at the iron making facilities and the requirement of liquid iron at the steel making facilities. It is logistically positioned in between the two facilities. Excess liquid iron from the BF is diverted to the GI plant for the production of GI. This eliminates reduction of hot blast volume at the BF while producing GI which can be used as internal feedstock as coolant in the BOF, or for external sales to be used by the cupolas, induction furnaces (IF) and electric arc furnaces (EAF). GI plants can be constructed and operated with capacities matching with the BF outputs. They are alternative to the pig casting machines (PCM) but with considerable higher capacities. The capacities of even twin strand PCMs are limited due to the solidification time of the liquid iron in the pig moulds. The PCMs also requires frequent mechanical maintenance as a consequence of the complex design. The GI has identical properties to that...