Open and closed circuit dry grinding of cement mill rejects in a pilot scale vertical stirred mill

In this study, separator rejects of a closed circuit cement tube milling were dry ground in a 10-l pilot scale vertical stirred mill. Tests were done as open and closed circuit. The results were evaluated by size distributions, Blaine surface area of the products and the specific energy consumed during the tests. Mill capacity and the stirring speeds were the investigated parameters for the open circuit tests, whereas closed circuit tests were carried out at a constant stirring speed but variable discharge rate. Five speed levels used in the open circuit grinding tests are 200, 400, 600, 800 and 1000 rpm. The capacities were determined to obtain product Blaine surface areas in the limits between 2000 and 5000 cm2/g. Closed circuit tests have resulted in 87%, 182% and 452% circulating loads.