The Study Of Several Organic Substances And Their Congeners As Slag Grinding Aids

Granulated blast furnace slag(GBFS)is the by-product released from blast furnace. According to calculation that 1 ton of pig iron can produce 0.5 ton of slag, there is approximately 283 million tons slag in the year of 2008. It is widely used in cement production as a cement mixing material and grinded with clinker to make slag cement in the past years, with the advantages of low hydration heat, high late strength increasing rate, etc. It also can reduce amount of cement clinker in cement production. Previous studies pointed out, while the slag specific surface is more than 400m2/Kg, the activity can be fully utilized. However, the slag grinding is more difficult than the clinker grinding because slag is vitreous structure. Intergrinding will not meet with the best activity, the specific surface of slag is below 300m2/Kg when the specific surface of cement clinker reached 400m2/Kg. So the slag requires separate grinding. After separate grinding slag, slag powder is not only be used in cement production as a cement mixing material , but also used in concrete substituting a part of cement Therefore, slag grinding should be separated from the cement production and become a new industry. However, the power consumption of separate grinding slag is very large, separate grinding slag which consumes electricity is 2-3 times more than grinding clinker. So slag grinding became a problem. There are two ways to resolve this problem. First, we can improve equipment. Because the price of mill for slag grinding is expensive, so it is not suitable for a small steel factory. Second, we can add grinding aids in the grinding process. The use of grinding aids can reduce fineness of powder, improve the physical and chemical properties of cement or concrete and reduce grinding power consumption of powder. In addition, the price is cheap. Therefore, adding grinding aids in slag grinding process is a good choice. But previous studies focused on the composite grinding aids and lacked systematic study on single-component grinding aids. This paper is based on the characteristics of slag of JiYuan Iron Steel Plant. And triethanolamine, glycerol, propylene glycol, propyl alcohol, ethylene glycol, ethyl alcohol, sodium dodecyl, sodium dodecyl sulfate, industrial waste residue calcium lignosulfonate which are chemically pure substances as grinding aids were adopted in order to systematically study the best dosage of the various substances, and effects of active groups impact on slag grinding process when the carbon chain length is similar, and effects of the carbon chain impact on slag grinding process when the numbers of active groups is certain.The main conclusions of this paper include: (1) The factors which decide grinding effect of organic substances are the kinds and numbers of groups, and carbon chain length and the molecular weight. The results show that grinding efficiency increases with more numbers of active groups when carbon chain length is similar. The longer the carbon chain is, the worse the effect of grinding is when the number of active groups is certain. Organic substances with large molecular weight have the neglectable grinding-help effect. (2) Effects of grinding is different at different grinding time. The effect of triethanolamine is better than glycerin at the grinding 15 minutes, but the results is opposite at the grinding 30 minutes. As the grinding time and mill temperature increasing, the effect of amido's electrostatic repulsive force dispersed powder is decreased. And the carbon chain length of triethanolamine is shorter than glycerol. (3)The best dosage of triethanolamine, glycerol, sodium dodecyl benzene sulfonate, sodium lauryl sulfate and calcium lignosulfonate are 0.06%, 0.04%, 0.1%, 0.08% and 0.08% respectively. (4) According to the early strength of slag cement configured slag powder with triethanolamine at the grinding 15 minutes, triethanolamine plays a major role when it can promote the hydration of cement particles and increase early strength. According to the early strength of slag cement configured slag powder with triethanolamine at the grinding 30 minutes, the organic matter plays a major role when it can prevent and reduce the strength of hydration. According to the latter strength of cement, the effect of grinding aids is weak. The effects of glycerol and calcium lignosulfonate is small. Sodium dodecyl benzene sulfonate and sodium lauryl sulfate significantly reduced the strength of slag cement.