Double-roller mill. The doubel-roller mills can be used to crush brittle materials such as ore, slag, glass, ceramics, battery materials, limestone, … up to a Mohs hardness of approx. 8.5. Depending on the material and size of the crusher, comminution ratios of 1:2, …, 1:5, max. up to approx. 1:20 can be realized.Web