| As the solid waste of industry production,furnace slag has the features of high output,complex composition,variable properties,environment damage,et al.Thus,proper settlement and disposal of furnace slag have always been the studying focus of researchers.With the development of larger and longevous blast furnaces,quality requirement of clean steel has become higher which caused more demand for high-quality refractory.The output of superior raw refractory is declining and their prices are rising year by year.The urgent task is to find an equal–quality,cheap and wide-sourced alternative for those refractory.Therefore,the goal of this paper is to thoroughly study the properties of ferro-titanium slag,ferro-vanadium slag and reduced aluminium chromium slag,and replace the counterparts of raw refractory with these slags according to their properties which will be the achievement of second use of resources and relieving the shortage of raw refractory.The basic properties of three kinds of slags were studied first.In-service conditions of castables for BF runner and through were then analyzed.And new type castables for copper ditch were finally studied and prepared.The results were as follows:(1)The main phases of ferro-titanium slag were calcium aluminate,rutile and corundum.The main phases of ferro-vanadium slag were calcium aluminate,alumina-rich spinel while reduced aluminium chromium slag mainly consisted of corundum.Because of their high alumina content,bulk density,strength and low water absorption,thermal conductivity,excellent refractoriness and slag resistance,these three kinds of slags could totally be used as raw materials for refractory.(2)These slag aggregates were added to Al2O3-SiC-C castables for BF runner and through.The effects of slag's gradation and addition on castables' properties were then studied.The results indicated that:a)With more ferro-titanium slag added,castables with excellent slag resistance had better flowability,lower apparent porosity and higher bulk density while the coldmodulus of rupture and cold crushing strength changed little.The influence on the hot modulus of rupture and the shock resistance was slight.The sample,using 12 wt%ferro-titanium slag,showed best properties and the aggregate size had minor effect on its properties.b)With more ferro-vanadium slag added to the castables,samples showed lower apparent porosity,higher bulk density while their cold modulus of rupture,cold crushing strength,hot modulus of rupture and the shock resistance declined.The smaller the size of ferro-vanadium slag was,the worse the properties of samples were.The best ferro-vanadium slag additions were 16 wt%(aggregate size of 8~5mm)and 8wt%(aggregate size of 5~3mm)respectively.c)When reduced aluminium chromium slag(size of 3~1mm)was added,castables showed lower apparent porosity and higher bulk density,cold modulus of rupture,cold crushing strength and hot modulus of rupture.The linear change rate rose first and then decreased.The castables had good slag resistance and the slag size had slight effect on its the shock resistance.When reduced aluminium chromium slag(size of 1~0mm)was added,castables' apparent porosity and hot modulus of rupture decreased.Its linear change rate,bulk density and cold modulus of rupture increased.Cold crushing strength of castables rose first then decreased and the shock resistance become poorer while slag resistance remained fine.When multiple-size slag was added,those properties mentioned above didn't change a lot.(3)By studying the aggregate gradation,volume stability and dispersion of castables,a kind of castables for new type converter copper ditch was prepared using ferro-titanium slag and reduced aluminium chromium slag as main raw materials. |
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