Minimization of impurities content in Si, necessary for its application as semiconductor material, was performed by using directional crystallization of metallurgical grade Si (n-MG-Si) with 98 wt. % Si purity without intermediate stages. After pulling from melt, n-MG-Si goes into p-type Si with current carriers concentration (p) ~ 1016 cm–3 and Si has been purified practically from most of the impurities. The possibility of uncontrolled impurities removal from Si depends on impurities effective coefficient of segregation in Si. Therefore we have investigated the effective coefficient of segregation of unwanted impurities in Si crystals, obtained by pulling directly from MG-Si melt. In the presented article the effective segregation coefficient of major impurities in Si has been calculated and analysed in the dependence on the crystallization conditions. Effective coefficient of segregation makes possible estimate the capacity and efficiency of Si purification from impurities during crystallization from melt.