Abstract: Improvements in metallurgical conversion in accordance with the present intion consist in the preparation of a semifinished item (a charge stock) in the form of a pig by forming thereof in a molding box of a casting machine from a solid filler, for the most part an oxidizing agent, and a liquid pig iron followed by cooling, provided said solid filler and said liquid pig iron undergo, in the process of forming, an action which prevents the floating up of the solid filler in the liquid pig iron. Such an action is effected both by applying a mechanical force, in particular by providing a casting machine with a cantilever (8) having a hollow roller (9) which rests on a molding box (2) and a weighting material (10), and by choosing relative dimensions of the solid filler pieces and selecting a rate of pig casting. Optimal conditions for using such semifinished item for metallurgical conversion which in accordance with the present invention is carried out in oxygen converters and arc furnaces are described.