Study On The Preparation And Properties Of Blast Furnace Slag Based Glass-ceramics

Blast furnace slag(BFS)is a by-product produced in the process of ironmaking,with high annual emissions.Now,the main treatment method of BFS is comprehensive utilization,but the utilization rate of BFS in China was only about 80%.As a typical solid waste in the metallurgical field,the problem of high value-added and high-volume comprehensive utilization of BFS has been a hot and difficult issue of researchers’ attention.In this thesis,based on the existing research,glass-ceramics with high added value were prepared by a sintering method using BFS,feldspar,and waste glass as raw materials,which were a lowcost,high-efficiency,and high-volume processing method for BFS.The specific work is as follows:Herein,the effects of composition and sintering temperature on the phase composition and microstructure of glass-ceramics were investigated according to the characteristics of raw materials,and the anorthite-diopside composite glass-ceramics were successfully prepared when the additional amount of BFS was 70 wt.%,a large amount of akermanite precipitated.There were a large number of macro pores,micropores,and sintering shrinkage pores in BFS-based glass ceramics.The residual sulfur of BFS overflows in the form of SO2 during the melting process,and there was still sulfur remaining in the parent glass.A large number of pores appeared in pure reagent glass-ceramics after adding CaS,and the foaming effect increased with the increasing addition of CaS.Based on clarifying the foaming mechanism of BFS-based glass-ceramics,NaOH,8H2O·Ba(OH)2 and KOH were introduced as modifiers to regulate the foaming behavior,and the effect of KOH was the most significant.The addition of 8H2O·Ba(OH)2 did not change the type of crystal phase,and the crystal phase was still dominated by anorthite and diopside.The addition of NaOH makes the glass-ceramics precipitate kyanite,and the addition of KOH leads to the precipitation of akermanite.The addition of a modifier reduced the polymerization of the silicon-oxygen network,promotes the depolymerization of chain silicon-oxygen[Si2O64-],increases the amount of non-bridgeu oxygel.Sulfur can replace more non-bridged oxygen to reconstruct the glass network.During the sintering process,sulfur escapes again in the form of SO2 to form tiny pores.However,the addition of KOH increased the stability of the sulfur-containing silicon-oxygen monomer and reduced the emission of SO2.When the additional amount of KOH was 1.5wt.%,there were almost no macroscopic pores in the glass-ceramics,and the size of microscopic pores was also significantly reduced.The main crystal phases were anorthite and diopside.With increasing addition of KOH,the microscopic pores were further reduced,but when the KOH addition was 3.5 wt.%,the alkalinity of the glass-ceramics is further increased,which makes the akermanite precipitate.Based on the above research,the effect of the sintering system on the properties of BFSbased glass-ceramics and modified glass-ceramics were studied.The modified glassceramics had almost no obvious macroscopic pores under various sintering temperatures,heating rates,and holding times,and the main crystal phases were anorthite and diopside,and the sintering adaptation range is wide.The density of BFS-based glass-ceramics and modified glass-cera1ics was 1.328 g/cm3～2.25 g/cm3,the water absorption was 0.105%～2.050%,the mass loss rate of acid corrosion resistance fluctuates greatly from 0.011%～7.670%,and the mass loss rate of corrosion resistance was relatively stable from 0.011%～0.294%.The glass-ceramics had better alkali corrosion resistance,and the acid solution will erode the glaze of the glass-ceramics.