Actual problem in metallurgy of the depletion of available resources has led to the search for ways to extract them from industrial waste. The extracted components can be used later in production, which is an alternative to current resource bases. Electric-arc furnace (EAF) slag and ladle furnace (LF) slag, containing a significant amount of silicate and metal components, are one of the main wastes in ferrous metallurgy. None of the slag is completely recycled, however, with their joint processing, their complete utilization is possible with the production of valuable products from them, which can be sent to the metallurgical and construction industries. This possibility has become the subject of the study. The possibility of joint processing of this slag was studied and confirmed to produce Portland cement clinker and cast iron from it that meet the requirements of normative documents. The results of mathematical modeling, the experimental technique are shown, step-by-step results, intermediate and final conclusions for model and real slag are displayed. The chemical compositions of the charge have been determined, which make it possible to process slag completely, without the presence of excess residues or waste. The result of such processing is pig iron and Portland cement clinker of quality that meets the requirements of normative documents. The results of measuring the viscosity of the slag compositions are described, the description of the obtained slag phases is given, and the final temperature regime is presented. The results of industrial tests of the developed recycling method are given. A complete technological chain is presented, involving the use of rotary inclined furnaces, a study is shown for the feasibility of using these furnaces in comparison with ore-thermal furnaces.