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The technological cycle of many processing companies in agro-industrial complex generate wastewaters, which contain emulsified fats, oils and surface-active substances. Depending on the type of pollutants, their concentrations and requirements to quality of the treated wastewaters, various purification methods can be used - mechanical, chemical, physical-chemical and biological. The most widely used and available method of reducing the stability of suspended or emulsified industrial wastewaters is using mineral coagulating substances, and among them, mostly, aluminum and iron compounds. Modifying the coagulants with, for example, titanium compounds, sodium chloride solution or silicic acid gel allows increasing the purification efficiency of suspended or emulsified wastewaters. Adding a dispersed phase (finely-dispersed silicon earth, bentonite clay) to multicomponent wastewaters as modifying admixtures accelerates the micelles formation process and sedimentation rate. The dispersed components do double service – as a sorbent for soluble impurities and as a weighting agent for coagulants hydrolysis products, which promotes separation of heterogeneous systems and increases the effluents purification efficiency. This paper suggests a method of emulsified wastewaters purification with a composite reagent – ferrosilicon flocculant-coagulant, obtained as a result of steelmaking slags modification with sulfuric acid solution (1:1). As a result of slag acid treatment the iron compounds and silicic acid gel are formed, which act as a coagulant and a flocculant, respectively, and the dispersed phase, presented with calcium sulfate and non-dissolved slag compounds, acts as an adsorbent of soluble substances and as a weighting agent for hydrolysis products. In the experiments a model wastewater with lipid concentrate content 1 g/dm3 and the initial turbidity 640 NTU was used. It is demonstrated that the obtained flocculant-coagulant at the consumption rate 0.1 g/dm3 provides emulsion purification efficiency 99.88% and 99.92% at being used as a suspension and as a powder, respectively [ABSTRACT FROM AUTHOR]