Preparation Of Ferronickel-Based Magnesium Cement And Its Application In Thermal Insulation Board

Ferronickel slag-based magnesium cement(FSMC)is a special magnesium oxychloride cement material prepared by mixing ferronickel slag,hydrochloric acid and light-burned magnesium oxide powder.It has the advantages of fast setting and hardening,high strength,light weight,high flame retardancy,high and low temperature resistance and easy forming,but its poor water resistance limits its application range.As an industrial waste residue produced in the process of producing ferronickel,the application of ferronickel slag in FSMC can not only be fully utilized to solve the environmental problems of ferronickel industry,but also find a large source of raw materials for magnesium oxychloride cement industry.In order to conform to the development trend of national green building materials,this thesis studied the optimal mix ratio of FSMC.based on this,a kind of modified composite insulation board with green environmental protection,high strength and light weight was prepared,which is of great significance for realizing energy conservation and emission reduction and developing circular economy.The main research contents of this thesis are as follows:(1)FSMC was prepared by ferronickel slag,hydrochloric acid,light-burned magnesium oxide powder and water.The mechanical properties,apparent density and water resistance of each group of specimens were tested by orthogonal test.The effects of hydrochloric acid,lightburned magnesium oxide powder and water content on the above properties were analyzed.Based on the regression analysis of the experimental data,the fitting model of FSMC about the above performance was obtained.The results showed that hydrochloric acid,light burned magnesia powder and water had great influence on the water resistance,apparent density and mechanical properties of the specimens,respectively.(2)Phosphoric acid(PA),tartaric acid(TA),phosphoric acid + silicone-acrylic emulsion(PA/SE),tartaric acid + silicone-acrylic emulsion(TA/SE)were added into FSMC for experimental study.The effects of four admixtures on the setting time,compressive strength,water resistance and water absorption of each group of specimens were analyzed.The results showed that the admixture could effectively improve the water resistance of each group of specimens,and the water resistance of specimens with compound admixture was better than that of specimens with single admixture.Admixtures could greatly reduce the compressive strength and water absorption of the specimens,and prolong the setting time.Compared with the specimens with single admixture,the specimens with composite admixture had lower compressive strength and water resistance,and shorter setting time.(3)On the basis of the optimal mixture ratio of water resistance modification,polyvinyl alcohol fiber(PVA fiber)and polystyrene foam particles(EPS particles)were added into FSMC for experimental research.The effects of PVA fiber content on the flow performance and strength of each group of specimens were analyzed.The effects of EPS particle content,particle size and gradation on the strength,apparent density and thermal conductivity of each group of specimens were also analyzed.The insulation board was manufactured by using ferronickel slag-based lightweight magnesium cement(FSLMC).The results showed that the addition of PVA fiber reduced the fluidity of FSMC,and the strength of the specimen increased first and then decreased with the increase of the PVA fiber content.Adding EPS particles reduced the strength,apparent density and thermal conductivity of each group of specimens.Adding EPS particles of various particle sizes was more favorable for improving the thermal insulation performance of the specimens.