A test and evaluation method of ore and coke coupling metallurgical properties
The reaction and characteristics of iron ore and coke in various areas of the blast furnace(BF)are impor-tant factors affecting the efficiency and yield of BF ironmaking,so that accurate evaluation of the quality of ore and coke has been arousing interests from ironmakers.The testing methods and indexes for evaluating the metallurgical properties of ore or coke have rapidly developed,and some methods have been standardized,including the method for determination of iron ore softening-melting performance under load and the determination of coke reactivity index and coke strength after reaction,etc.The methods have been widely adopted by iron and steel enterprises.Howev-er,it is still difficult to calculate the technical-economic indexes of BF from on the experimental results based on cur-rent testing methods and indexes.This may be due to insufficient simulation on the interaction between ore and coke through the entire process of reduction,solution loss,softening and melting in BF.Assigning values to the correla-ted behaviours and characteristics of ore and coke and constructing an indicator system to evaluate the interaction be-tween them could not be achieved.Therefore,a test device and evaluation methodology(Qisunny method)have been invented,which deploy samples with coke-ores-coke layer structure in the crucible integrating the reduction un-der the load-thermogravimetric-gas analysis to simulate coupling ores and coke behaviours and properties,such as i-ron ore reduction,coke solution loss,burden softening,melting and dropping.The device and methodology can conduct coke and ore coupling behaviours and properties test and evaluate its coupling performance.The test results of changing burden structure and coke type showed that coupling coke and ore metallurgical performance evolved with different zones with distinct boundary in an order from indirect reduction zone to indirect and direction reduction co-existing and softening zone,to smelting direct reduction zone and to dripping direct reduction zone.The perform-ance evaluation parameters included the temperature and the temperature interval of different zones,the indirect and direct reduction rate,the total reduction rate,the permeability parameters in melting zone,the solution loss rate and strength after dissolution of the top layer coke.The solution loss reaction of coke mainly taken place in the melting zone.The solution loss rate of the upper layer coke was close to the traditional coke reactivity index while its strength after dissolution was higher than the traditional coke strength index after reaction.The method can provide a totally new option for evaluating coupling coke-ore performances and optimising burden structure.
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