Pneumatic separation is one of the available methods for cleaning seed mixtures. Variously shaped seeds, including spherical (vetch), elongated (wheat), and pyramid-shaped seeds (buckwheat), were analyzed in this study. A seed mixture containing 80% of main crop seeds and 20% of other crop seeds imitating impurities was separated in a pneumatic separator with the shape of an inverted cone in a stream of air. The regression equations describing the separation efficiency of the main crop seeds and other crop seeds imitating impurities (η) and the separation efficiency index (ε) were characterized by high and very high fit to empirical data. The coefficient of determination for the analyzed seed mixtures ranged from 0.71 to 0.99. The conical separator supported effective separation of seed mixture components in a stream of air.

In machines and devices used for separating and cleaning seed mixtures, the components of such mixtures can be separated in a stream of air. The efficiency of separation of a two-component (model) mixture containing wheat kernels and buckwheat nutlets was investigated. The main crop seeds and other crop seeds imitating impurities accounted for 80% and 20% (w/w), respectively. The experiment involved a pneumatic cleaning device with an immobile conical surface, designed by the authors, where mixture components are separated in a stream of air. The seed mixture was separated in a separator with the shape of an inverted cone, where the seeds were set into motion by a stream of air. The separation efficiency of the analyzed two-component mixture in the designed separator exceeded 78%. Regression equations describing the separation efficiency index of the entire seed mixture (ε) and the separation efficiency of the main crop seeds (ηp) and seeds imitating impurities (ηz) were derived. The coefficient of determination (R2) for the above regression equations describing the separation efficiency of the mixture components (main crop seeds and seeds imitating impurities) and the separation efficiency index of the entire seed mixture ranged from 0.81 to 0.94. This result indicates that the developed equations were characterized by satisfactory and highly satisfactory fit to empirical data, and that they can be applied to accurately predict the quality of the seed separation process in the cleaning device designed by the authors. The developed equations can be effectively used to model and automatically control separation processes in the proposed separator.