화학공학소재연구정보센터
Powder Technology, Vol.105, No.1-3, 436-442, 1999
Change from pressure crushing in roller mills to impact crushing in production of mineral sand
North Cape Minerals operates a nepheline syenite mine, delivering raw materials to glass and ceramic producers all over the world. Removal of unwanted minerals is done dry. Most of the production is delivered as Altafloat with a particle size defined by d(99,9) = 500 mu m and d(8) = 74 mu m. This requires a comminution circuit which does not produce excess fines. Originally, roller crushers in closed circuit with screens were used for this purpose. This operation was continuously improved over 30 years but there were 20 parallel units and too much maintenance. After 3 years of testwork, it was therefore decided to replace the roller crushers by Barmac crushers. This has resulted in a slightly higher production of fines, but operation is much simpler and more economical partly because the feed size for fine crushing is increased from -8 to -12 mm.