Study On The Application Of Steel Slag Multi-phase Cement Clinker

Nowadays,the large steel slag emission and its low comprehensive utilization rate are the common issues that restrict the sustainable development of iron and steel industry.The massive accumulated steel slag is not only a serious waste of resources,but also creates pollution to soil and groundwater.The calcining technology of steel slag multi-phased clinker is to directly fed unpulverized steel slag through uptake flue into rotary kiln.It's calcined into cement clinker which overcomes the abrasion and stability problems in the application of steel slag and making it possible for high-level and high-added utilization of steel slag.This dissertation is aimed to study the composition and characteristics of steel slag multi-phased clinker(SSMC).Comparing the mechanical properties and durability of cement prepared by SSMC and conventional clinker(CC)to lay a foundation for the engineering application of SSMC.1.The mineral composition of SSMC is consistent with that of CC.In contrast to CC,the content and crystallinity of C₃S is higher in MC.The grindability of MC is similar to that of the CC,and its soundness detected by the boiling process and the autoclave method is qualified,besides,it has higher cementitious reactivity than CC especially in early hydration.It breaks bottleneck in steel slag utilization that is low activity,poor grindability and volume stability.The production of MC has great economic and environmental benefits.The output of clinker increases without changing other production parameters,it reduces 29.2 tons of CO₂ emissions per ton of clinker.2.The strength,permeability resistance,sulfate resistance and abrasion resistance of P.I and P.S Portland cement prepared by MC are better than those prepared by CC.At the age of 90 days,the compressive strength of P.I and P.S Portland cement prepared by MC were 14%and 8%higher than corresponding cement prepared by CC respectively.Compared to mortar prepared by CC,the passing charge of mortar prepared by MC were 20%and 17%lower in P.I and P.S cement respectively.The sulfate resistance coefficient of P.I cement prepared by MC reached 1.11,and the wear rate of P.S cement prepared by it was only 0.375 kg/m².MC has a better adaptability with blast-furnace slag.3.The content of C₄AF was higher and the content of C₃A was lower in SSMC.The cement prepared by SSMC has a higher strength,stronger anti-erosion ability and good grindability.From the perspective of clinker composition and cement performance,cement prepared by SSMC is inclined to be a kind of road cement,which takes both mechanical properties and durability into account.It is expected to be used in the construction of cement concrete infrastructure in roads,coastal areas and salt lakes with relatively harsh environment.