Three new crystalline forms of pemetrexed diacid, preparation methods and uses thereof are disclosed. When multiple cyclones of the present invention are affixed between upper and lower tube sheets in a separator device, fine particle removal is possible to the extent required 1) by stringent regulations governing particulate emissions into the atmosphere, or 2) to prevent damage to turbine blades in downstream power recovery equipment. The movable portion is formed with a plurality of through-holes. An attachment member is attached to the substrate.