Development And Research On Preparation Of Porous Ceramic Materials By Metallurgical Steel Slag

The continuous development of the steel industry has led to a continuous increase in steel slag emissions.At present,the state vigorously promotes the construction of standard system for solid waste treatment and utilization,and has carried out a lot of solid waste treatment work,but the utilization rate of steel slag is still very low.At the same time,ceramic raw material resources are scarce,and it is urgent to find new alternative raw materials.Therefore,it is of great significance to apply metallurgical steel slag to the preparation of porous ceramics.Using metallurgical steel slag as the main raw material,porous ceramics with high porosity and low density were prepared by chemical foaming,direct foaming and organic foam impregnation,respectively.The research contents are as follows:The foaming effects of different foaming agents were co MPared with steel slag and kaolin as raw materials.The optimal ratio of raw materials,sintering temperature and foaming agent content were determined,and the appropriate type of foaming agent and the amount of foaming agent were determined by co MParing the foaming effects of different chemical foaming agents.And analyzed the changes of the sample’s bulk density,porosity,and compressive strength.Research shows that the optimal amount of steel slag is 60%,and steel slag can reduce the softening temperature to a certain extent and promote the foaming of the sample The most suitable chemical foaming agent is silicon carbide.When silicon carbide is used as foaming agent,the foaming effect is better than other foaming agents(calcium carbonate,calcium sulfate,sodium carbonate,carbon powder).The increase in the amount of silicon carbide leads to a decrease in the density of the porous ceramic,but the compressive strength of porous ceramics is low when the content exceeds 1%(≤0.4 MPa).The compressive strength is 0.4 MPa,the volume density is 196.8 kg/m~3,the porosity is 93.2%,and the crystalline phase is mainly akermanite and a little amount of anorthite,when the content of steel slag is 60%and Si C is 0.8%.Porous ceramics with steel slag were prepared by direct foaming method.The porous ceramics were prepared by using steel slag and metakaolin as raw materials and sodium dodecyl sulfate(SDS)as foaming agent.This experiment explored the relationship between the volume density,mechanical strength,porosity and pore structure of the sample affected by the ratio of raw materials,sintering temperature and holding time.The results show that with the increase of steel slag content,the main crystalline phase of the porous ceramics changes from calcium feldspar to calcium aluminum feldspar.The increase of SDS content will cause the density of porous ceramics to decrease,but the pore wall becomes thinner and the pores are not uniform when the SDS content is more than 0.1%.When the ratio of steel slag to metakaolin is 4:6,the foaming agent content is 0.8%,the porous ceramic sample sintered at 1190℃has a relatively complete pore structure,the pore size is between100～600μm,the volume density is 446.6 kg/m~3,and the compressive strength is 0.5MPa.Porous ceramics with high porosity and low bulk density were prepared by using steel slag and kaolin as main raw materials and polyurethane sponge as template.The effects of steel slag particle size,zirconia addition,the solid content of the slurry,and the addition of polycarboxylic acid water-reducing agent on the properties of ceramics were studied.In addition,by adding a surfactant(Sodium dodecyl sulfate)to form fine pores on the original framework of the three-dimensional network porous ceramic,the shortcomings of the single as well as the uncontrollable density and porosity of the porous ceramic,which are produced by the template method,are improved.When the grinding time of steel slag is 90 min,the content of zirconia is3%wt,the solid content of ceramic slurry is 64 wt%,and 0.6wt%polycarboxylic acid water-reducing agent and 0.4%of surfactant are added,the prepared porous ceramic skeleton is clear and good.The porous ceramic has a low bulk density(as low as 157.869 kg/m~3),high porosity(about 94.05%)and high compressive strength(0.2MPa).The crystalline phase of it is mainly composed of anorthite,gehlenite,forsterite and quartz.The addition of zirconia,water-reducing agent and surfactant only changes the macrostructure of porous ceramics,and does not change its crystal phase composition.The preparation of porous ceramics from steel slag not only solves the recycling problem of steel slag,but also provides a good substitute for main raw materials of porous ceramics.Using direct foaming method and organic foam impregnation method to prepare porous ceramics with steel slag can change the defect of single pore structure in porous ceramics prepared by organic foam impregnation method,and form uniform pores on the skeleton,which further reduces the density of porous ceramics.When the addition amount of SDS increases from 0%to 0.4%,The density of porous ceramics decreases from 236.7 kg/m~3to 157.869 kg/m~3,and the porosity increases from 85.3%to 94.05%.The combination of direct foaming method and organic foam impregnation method only changes the pore structure of the porous ceramics,reduces the density of the ceramics,and does not change the crystal phase composition of the porous ceramics.