Study On The Surface Modification Of The Steel Slag

With the development of industry, the great need for more and more steel bringsus bunch of steel slag disposed, which has occupied lots of land and polluted theenvironment heavily. It is necessarily for people to reuse the steel slagcomprehensively turning the waste into useful material.At current time, the steel slag is used as component of cement and constructionaggregate material. Deep research should be carried out to find new recycle way.Recently the surface modifying becomes an important method to treat powder,however it is not reported that the steel slag has been treated in this way.In this paper, in order to find new application, several ordinary surface active agentswere added into the planetary mill to grind with steel slag. Then the modifying effectswere studied to discover the new character of the modified steel slag.The physical and mechanical properties, such as tensile strength, impact strength,flexural strength and thermal deformation temperature, of the PP complex which wasfilled with the stearic acid modified steel slag were tested. At the same time thecementitious property of the modified steel slag was studied by the little lumpsexperiments.The analysis of the density and size of the particles indicated that the activeagents selected had good grinding-aid effect on the steel slag. Obviously the grindingprocess can be divided into three stages according to time, namely: big particlescrashed, while number of small particles increased; small particles re-united andbecome bigger; the grinding process reached balance with the size of the particlesunchanged.It is found through SEM that after modifier added big change had happened tothe surface of the steel slag with small particles increased and the unregulated shapesturned into more regular ones. The regulation of the steel slag particle was improvedwith grinding time.The surface modifying of steel slag by stearic acid resulted in the regular change of iactive index with the change of grinding time and the quantity of stearic acid added.There was a best numerical value of grinding time and quantity of stearic acid in orderto achieve the best modifying effect. FI-IR analysis indicated that the stearic acidacted with steel slag through chemical bond.The X-ray diffraction found that aberration appeared in structure and crystal,amorphous part of the particles grew and at last a balance reached.The property of the PP composite was tested when the PP was modified by the steelslag which was modified by stearic acid. It is found that with the increasing of steelslag the tensile and impact strength decreased, while the flexural strength increasedwhen low quantity (less than 30%) of steel slag was added. And at the same time thethermal deformation temperature was higher.It is found in the little lumps experiments that the modified steel slag affected theproperty of the steel slag greatly. Using Mugai to modify the steel slag can lead to thereduction of the quantity of water used in the little slumps experiments, and thecompressive strength increases with the water-cement ratio reducing. But too muchMugai added resulted in the down of the little slumps' compressive strength. Thecompressive strength for 28 days is 4.19 times lower with the water-cement ratio 0.28.The little slumps experiments indicated that the early period compressive strengthgets higher when the steel slag ground with LYF, rising 1.64 times form the steel slagun-ground with LYF in the same conditions, and at the same time the late periodincreased heavily. So the selected modifiers not only have the effect of grinding aidbut also play the special role when they used in the concrete industry.