Experimental Studies of the Process of Grain Purification from Impurities in a Pneumatic Separator of a Pneumatic Hammer Crusher

This article analyzes various types of pneumatic separators designed for grain purification. The methods that make it possible to effectively remove metallomagnetic and heavy impurities from the grain mixture are also noted. The study revealed the key technological parameters that determine the quality of the purified product: the effectiveness of removing metallic and heavy impurities. The main types of designs of pneumatic separators used for grain cleaning are analyzed and structured. However, they have several major drawbacks. Firstly, they can only remove metallic or heavy impurities, and secondly, with a combined approach, the cleaning quality may be insufficient. To solve these problems, we have studied modern research on the methods and designs of pneumatic separators. Based on the results obtained, we proposed the design of a hammer crusher with an integrated pneumatic separator equipped with a screw working body. To create a mathematical model of the process of cleaning grain from impurities in the pneumatic separator of a hammer crusher, we identified the main factors that affect this process, as well as the levels of their change: 1) the pitch of the turns of the screw working body is 40, 60 and 80 mm; 2) the depth of the sedimentation chamber is 40, 80 and 120 mm; 3) The specific feed rate is 0.28, 0.53 and 0.78 kg/s. These factors were chosen taking into account their influence on the process of grain purification from impurities and ensuring rational conditions for conducting the experiment. An experimental installation was constructed, which includes a pneumatic separator with an inlet pipe on which a magnetic trap is installed, a sedimentation chamber, as well as three types of screw working bodies. As a result of experimental studies, a mathematical model of the grain purification process from impurities in the initial variables has been obtained. The rational values of the design-mode technological parameters of the pneumatic separator are determined.