Study On Preparation Of Road Portland Cement From Nickel Slag

Nickel slag is a solid waste of nickel ore that is smelted in an electric arc furnace at a temperature of 1500~1600°C to produce by-product slag that is cooled by water or air.It is mainly composed of amorphous silica,magnesium olivine,enstatite and other minerals.Recent studies have demonstrated the potential of nickel slag as construction materials.As fine aggregates and cement admixtures,they can meet the requirements for the preparation of high-density concrete;it can be used as a raw material to prepare new construction materials such as glass-ceramics and unburned bricks with excellent properties.At present,there are not many studies on the preparation of cement clinker from nickel slag.In this paper,nickel slag is used as raw material to prepare road Portland cement.The burnability of cement raw meal with different amounts of nickel slag is studied.The mineral composition of clinker and the hydration products of cement were analyzed by X-ray diffraction.The microscopic morphology of the clinker and hydration products was observed by metallographic microscope and scanning electron microscopy.The free calcium oxide content of the clinker and the mechanical properties and wear abrasion of the cement were determined.Utilization of nickel slag as a iron raw material in Portland cement for road was studied.The results show that the proper amount of nickel slag and mineralizers can help improve the burnability of raw meal and reduce the f-CaO content of clinker.The road cement prepared has the high strength and good wear resistance characteristics.The best process is that use 79.5wt%limestone,9.5wt%clay,10wt%nickel slag,1wt%composite mineralizer,calcined at 1370?for 60 minutes.A large number of well-developed A-ores,round-grained B-ores,and a small amount of mesophase can be seen in the clinker-facies map prepared by this process.The 3,28 days compressive strength and bending strength of cement were 30.9 MPa with 7.5 MPa,and 75.2 MPa with 11.2 MPa.The 28 days cement mortar had a wear volume of 1.9 kg/m~2,and the stability was satisfactory.The SEM images of hydration for 28 days can be seen in a large number of C-S-H gels.The growth of ettringite is complete and interwoven into a dense network structure.Utilization of nickel slag as a silicon raw material in Portland cement for road was studied.The results show that using nickel slag,fly ash,desulfuration gypsum,limestone,clay and so on preparation of silicate cement road is feasible.The road cement produced by the experiment has the characteristics of later strength,because the content of C2S in clinker is relatively high,which leads to its early hydration rate,which is favorable for the later strength development.The addition of desulphurized gypsum can reduce the incorporation of limestone and save energy,and the amount of desulfurization gypsum added to cement has little effect on the performance of cement.The best preparation technology is that use 14wt%nickel slag,74wt%imestone,4wt%fly ash,7wt%steel slag,0.6wt%desulfurization gypsum,0.4wt%fluorite,calcined at1370?for 60 minutes.In this process,f-CaO content is 0.22%,and the cement paste3d,28d compressive strength and folding strength are 21.9MPa,6.9MPa and 52.4MPa,14.5MPa,and the strength grade is 42.5,and the abrasion amount of 28d is 2.1kg/m~2.