1. Refractory particles of Polirit introduced into a cast iron melt are passive graphitizing centers around which graphite inclusions form. Growth and configuration of these inclusions is regulated with a reduction in melt temperature by precipitation on their surface of surface-active elements present in the melt. There is no cast iron melt refining by such surface-active elements as sulfur, oxygen, etc. 2. In order to obtain spheroidal graphite in cast iron it is necessary to introduce into the melt modifying elements forming with surface-active elements, primarily sulfur and oxygen, refractory compounds which are active graphitizing centers, and lead to removal of these elements from participation in the crystallization process.