Effect and Behavior of Liquid Additive Molecules in Dry Ultrafine Grinding of Limestone [Translated]†

Abstract

The effect of liquid additives such as alcohol and glycol on the ultrafine grinding of limestone was investigated by using a vibration rod mill. Liquid additives used in the present work were three alcohols and two glycols with different alkyl groups. The experiments were carried out by a batch operation, and the change in specific surface area of limestone with grinding time was measured by BET adsorption method. The behavior of methanol molecules added as an additive was traced by monitoring the temperature and pressure in the grinding pot during grinding. The results showed that alcohols and glycols promote the ultrafine grinding of limestone, and that the maximum specific surface area of limestone obtained with additives is proportional to the amount of the additive. The stepwise addition of a small amount of additive was more effective rather than adding the whole amount at once in increasing the grinding rate of limestone. It was also found that the degradation of crystal structure of limestone was controlled by the addition of alcohol. The grinding status of limestone could be traced by monitoring the temperature in the grinding pot, and the measurement of pressure change in grinding pot revealed that the additive molecules are chemisorbed on fresh surface of limestone created by the grinding.† This report was originally printed in J. Soc. Powder Technology, Japan, 42, 178-184 (2005) in Japanese, before being translated into English by KONA Editorial Committee with the permission of the editorial committee of the Soc. Powder Technology, Japan.

Keywords

• grinding aid
• limestone
• ultrafine grinding
• alcohol
• pressure change
• temperature change