A stable and efficient blast furnace operation requires proper control of hot metal and slag drainage from the hearth. Many operational problems such as non-dry casts, blow outs, excessive hearth lining wear and low-blast intake arise when the liquid level in the hearth exceeds the critical limit where hearth coke and deadman start to float. Since the direct measurement of the hearth liquid level is practically impossible due to high temperature and pressure inside the furnace, it is therefore important to estimate the liquid level in the hearth and display it to the operators on real-time basis for efficient cast management. This paper presents a system, called hearth liquid level monitoring (LLM), which simulates the liquid level and drainage behaviour of the furnace hearth. It is based on the theoretical hot metal and slag generation rate from the specific oxygen rate and the computed drainage rate from torpedo radar signals and the slag flow measurement system. The system advises the blast furnace operator when to initiate tapping and close the taphole when the liquid level is controlled. It also alerts operators when to use the larger drill bit diameter for opening the next cast.

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The key to excellent casthouse operation are low cost, high productivity, dry hearth and high casting rate while minimising the consumable material. The stable blast furnace operation requires proper control of drainage rate of liquid hot metal and slag from hearth. The productivity of blast furnace can be effectively increased if drainage rate is considerably increased. If the drainage rate is controlled, the periodic tapping of hot metal and slag from hearth can be made effective. This paper highlight the improvement made in casting practice by controlling the hearth liquid level in blast furnace. The improvements have made significant change in casthouse management. It is well demonstrated that various casthouse operations have migrated from one regime of operation to another regime and various consumable items are significantly reduced. The importance of increasing the drainage rate in improving the productivity of blast furnace is explained in details.

The pulverized coal injection (PCI) is pursued to reduce the hot metal production cost by replacing the expensive metallurgical coke with the non-coking coal. Increasing the PCI rate causes various difficulties in the blast furnace (BF) operation. In the present work, an attempt is made to review the various aspects of PC injection in BF such as the challenges with increasing the PCI rate and modifications in the injection system to circumvent the concerns related to higher PCI rate. Various methods for detecting the tuyere blockage and failure caused due to the high PCI rate are elaborated. The factors influencing the combustion of coal in front of tuyeres have been discussed and their impact in the replacement ratio has been discussed. Further, recommendations are made to improve the coal combustibility in front of tuyeres.

The stability of the blast furnace (BF) process depends on the quality of raw materials charged into the BF. Apart from various process variables, slag viscosity and slag fluidity are key parameters that require due attention for the stable BF operation. The varying Al 2 O 3 content in slag increases the viscosity of slag and thus hinders the separation of slag from hot metal during the casting process. This leads to the deterioration of hot metal quality because of the entrapment of slag during the slag-metal interfacial reaction. In this work, an attempt is made to utilize the high alumina content raw materials and to reduce the Al 2 O 3 content in the final slag. The high alumina content in slag increases the liquidus temperature and viscosity of slag and causes an adverse effect on BF operations. To countermeasure the effect of alumina, slag volume is increased and basicity along with MgO was increased. It has been demonstrated that MgO addition as a flux is effective for compensating the effect of a high alumina burden. By increasing the MgO in slag, fluidity was maintained to ensure easy separation of slag from hot metal.