Abstract：In order to solve the material separation problem in the closed state, based on the gas-solid two-phase flow theory, referenced the closed nitrogen recycling system and combined with the mature air separation system of cement industry, the calculation formula of the material pneumatic separation with nitrogen or other inert gas was given, and the technical problem of nitrogen recycling and reuse were presented, which formed a systematic and viable application system.

Keywords: high-efficiency separator; pneumatic separation; nitrogen; closed-cycle system