Comparison of open and closed circuit mode using a dry horizontal stirred media mill with special regard to the powder flowability and residence time distribution. (15th March 2021)

• Record Type: Journal Article
• Authors: Prziwara, P.; Thake, S.; Breitung-Faes, S.; Kwade, A.
• Is Part Of: Minerals engineering. Volume 163(2021)
• Publication Date: 2021-03-15
• Subjects: Dry continuous fine grinding -- Open and closed circuit -- Dry -- Operated stirred media mill -- Grinding aids -- Powder behavior; Mines and mineral resources -- Periodicals; Ressources minérales -- Périodiques; Mines and mineral resources; Periodicals; Electronic journals; 622
• DOI: 10.1016/j.mineng.2021.106781
• Languages: English
• ISSNs: 0892-6875

Abstract

Graphical abstract: Highlights: Type and concentration of grinding aids determine the flow behavior of fine limestone powders. In open and closed circuit modes, both a too low and an excessive flow behavior led to unfavorable stress conditions. Open and closed circuit modes, however, show different effects in terms of the powder behavior. High flowabilities are critical for grinding in open circuits due to transport issues. For closed circuits, rather high flowabilities are advantageous. Abstract: A dry operated, horizontal stirred media mill was used for the fine grinding of limestone and compared in open and closed circuit modes. It was found that the choice of grinding aids as well as the stirrer tip speed are crucial for the mill operation, especially in terms of the grinding efficiency and the transport behavior through the mill. Independent of the process mode, both a too low and an excessive additive-induced flow behavior led to unfavorable stress conditions inside the mill, and thus, inefficient grinding. In the open circuit, especially high flowabilities turned out to be crucial, as thereby the stress conditions are negatively affected as a consequence of the material transport in combination with the overlapping impact of a mill- internal deflector wheel. Different important aspects were seen for the closed circuit grinding; especially when aiming for high finenesses or using high tip speeds, it is essential to ensure both a minimum flowability and a sufficient particle stabilization to ensure a fast removal of fine particles from the mill. High flowabilities in turn are not as critical during closed circuit grinding, but are accompanied by high material recirculations.