Study On Prestressing Strengthening Iron Tailings Building Ceramics

In recent years,our mineral industry has developed rapidly,the amount of iron ore mining is increasing,the amount of iron tailings discharged from the concentrator is also increasing,and the stock of iron tailings is also rising.In the long run,it not only occupies land,but also brings environmental and safety problems,which has become an important factor restricting the sustainable development of mining industry and endangering the ecological environment and safety around the mining area.Utilizing iron tailings as resources to produce building ceramics is one of the effective ways to solve the iron tailings stock.It can not only consume a large amount of iron tailings,solve the ecological problem,but also solve the shortage of raw materials in the pottery industry and create economic benefits.In this paper,high dosage raw materials of iron tailings from Xishimen area of Hebei Province were used to prepare building ceramics.Combined with prestressed ceramic reinforcement technology,ceramic coating and ion exchange were used to enhance the mechanical properties of building ceramics of iron tailings,and the best formula composition and process parameters were explored.The main research results are as follows:（1）Taking iron tailings,potassium feldspar and calcined talc from Xishimen as raw materials to prepare building ceramics,and taking flexural strength as the main performance index,the optimal formula composition was obtained,and the influence of sintering temperature,holding time and ball milling time on the flexural strength of building ceramics of iron tailings was explored,and the optimal process parameters were obtained.The results show that:iron tailings 45wt%,potassium feldspar 27.5wt%,talc27.5wt%,sintering temperature 1200℃,milling time 4 h,holding time 0.5 h,the maximum bending strength of 114.92 MPa.（2）The sintering range of iron tailings building ceramics is relatively narrow,adding Zn O can effectively broaden the sintering range of iron tailings building ceramics,by changing the amount of Zn O addition,explore the effect of Zn O addition amount on the sintering range of iron tailings building ceramics.The results show that the sintering range of iron tailings building ceramics is widened from 30℃（1180～1210℃）to 60℃（1140～1200℃）by adding 4wt%Zn O,and the broadening effect reaches the maximum,but the bending strength drops to 103.23 MPa.When the addition amount of Zn O exceeds4wt%,the sintering range is not extended,but the overall sintering temperature is reduced.（3）The ceramic coating was prepared by dolomite,Al₂O₃ and Si O_2,and the bending strength of the building ceramics of iron tailings was used as the main performance index to strengthen the coating formula,and the influence of coating thickness,holding time and ball milling time on the strengthening effect of the ceramic coating was explored,and the best technological parameters for the strengthening of the ceramic coating were obtained.The results show that the dolomite is 32wt%,Al₂O₃ 12wt%,Si O₂ 56wt%,coating mass percentage is 5wt%（thickness is 196.45μm）,holding time is 0.5h,milling time is 5h.The bending strength,microhardness and fracture toughness of iron tailings reinforced by ceramic coating increased from 103.23MPa to 148.51MPa,from 608.36kg/mm² to751.13kg/mm²,and from 1.71MPa·m^1/2 to 1.82MPa·m^1/2.Thermal shock resistance increased from 20～180℃to 20～280℃.（4）KNO₃ molten salt was used for ion exchange reinforcement.Na⁺ions in the building ceramics of iron tailings were exchanged by K⁺ion.By changing the exchange temperature and time,the bending strength of the samples after exchange was taken as the main performance index to explore the best technological parameters for ion exchange reinforcement.The results show that the exchange temperature is 400℃and the exchange time is 5 h.The bending strength,microhardness and fracture toughness of the building ceramics of iron tailings strengthened by ion exchange increased from 103.23MPa to167.81MPa,from 608.36kg/mm²to 816.22kg/mm²,and from 1.71MPa·m^1/2 to1.86MPa·m^1/2.Thermal shock resistance increased from 20～180℃to 20～220℃.