Scientific Management And Operation For Low-Cost Blast Furnace Ironmaking Process

Ironmaking is the largest energy consumption process in iron and steel plants, accouting for70%of total energy consumption, and the cost of hot metal is significantly important to the development of iron and steel plants. Currently the main problems in ironmaking process include the high materials’ price, the increasement of low-grad iron ores, the increasement of energy consumption, which are the reasons for the high cost of ironmaking. Therefore, scientific management for low-cost operation is the key for iron and steel plants to enhance their competitive power in the grim market conditions.Aimed to low-cost production strategy, in view of the pratical condition of Anyang Steel, the scientific management for low-cost operation, including development and application of model for low-cost burden design, the innovative pulverized coal injection process, decreasing fuel rate etc are investigated and discussed in the present thesis.The main contents and some selected conclusions are shown as following,(1) A mathematic model for low-cost burden design is developed. Based on the calculated results of the model and the practical conditions in2011, such as the iron ore resource and economic condition, the burden design for450m3of Blast Furnace (BF) is82%Sinter+1.17%Pellet+7.56%Lump ore (X3)+8.49%Lump ore0.78%Flux, and the burden design for2000m3of BF is78%Sinter+8.29%Pellet+6.44%Lump ore (X3)+6.79%Lump ore (X4)+0.49%Flux. The costs of raw materials for both BFs are decreased54.4CNY/tHM and40.5CNY/tHM respectively compared with the cost in2010. Therefore, the development and application of model for low-cost burden design is benefit to scientific management and further decrease the cost of ironmaking.(2) By the calculation on the uncombusted coal in BF, one can conclude that the uncombusted coal will not increase when the coal of Shenmu:Luan=2:1is injected at160kg/tHM. The injected amount can reach177kg/tHM with3%of oxygen-enrichment. So the injected amount will increase about40kg/tHM and the cost of hot metal will decrease25CNY/tHM compare with previous operation (less than140kg/tHM). (3) By analyzing the relationships of coal rate, coke rate, fuel rate, and utilization coefficient (productivity) of BF of Anyang Steel, some conclusions can be obtained, a) the coke rate is lowest (about320-330kg/tHM) when the coal rate is160kg/tHM, b) fuel rate is lowest (about470-490kg/tHM) when the coal rate is140-160kg/tHM, c) the utilization coefficient is highest (2.4-2.5t/m3.d) when coal rate is150-160kg/tHM. The optimum operation parameters for production’s goal, such as lowest fuel rat, can be obtained by analyzing the operation indices of continuous6months. Praclically the fuel rate can be stable at490kg/tHM by adoption these optimum parameters.(4) Experimental results show that, a) it has no obvious influence when the Light Burned Magnesite (LBM) addition is less than3%, b) adiabatic flame temperature increases when the LBM addition is less than4%, c) combustion rate of pulverized coal increases4-5%when the LBM addition is about5%, d) oxygen-enrichment can improve the effect of LBM on combustion rate. Based on the experimental investigation in lab, a pilot plant trial was carried out in Anyang Steel. The trial results show that, a) for BF6#, the coal rate decreases by12kg/t, coke rate decreases18kg/t,[Si] in hot metal decreases from0.59%to0.47%, b) for BF7#, the coal rate decreases by13kg/t, coke rate decreases2kg/t,[Si] in hot metal decreases from0.56%to0.41%. In economic aspect, the cost of hot metal increases5.2CNY/tHM if the lump ore proportion is fixed, but the cost will decreases2.2CNY/tHM if the pellet proportion is fixed with the pulverized LBM injection.(5) In order to stable and safe operation, the maintainance technology for hearth and prediction model for equipment failure are developed. By using the maintainance technology, the abnormal increasement of hearth temperature is solved, which has a positive role in low-cost ironmaking operation. The grey system GM(1,1) and metabolic model are combined in the prediction model, which can decrease workload and increase the predictable accuracy, also can reflect operation status of equipment in practical operation.The consequences of the experimental and theoretical investigation in present thesis could play a significantly important role in low-cost BF ironmaking process, such as reasonable burden design, optimum operation parameters, develop some innovative injection process, establish usable mathematic and predictable model, and eventually realize the integrated innovation process and reduce the cost of ironmaking.