In the production of steel by the electric arc furnace (EAF) process two different types of slags were produced, EAF slag or black slag and ladle furnace (LF) slag or a white slag. Produced slags prior to disposal were mixed and handed to a licensed waste collector with certain costs. In order to treat slags, remains from production with its usage value, as a co product, it is necessary to meet certain conditions of which the most important are physico-chemical characteristics. In this paper the black and white slag were compared through their physico-chemical characteristics, and regarding their differences, the possibilities of using them were shown. According the literature it was established that both slags are non-hazardous waste, and as such can be used for various purposes (cement industry, road construction as a substitute for natural mineral aggregates, agriculture for soil improvement etc.). The chemical composition of the slags showed that the white slag from black differs most in the content of Ca and Mg so that those slags should be collected separately. Namely, with regard to the above, each of them can find their specific purpose and a place in the market. Therefore, mentioned slags, through meeting the legal issued conditions, should be renamed from the waste to co-product, and therefore instead of disposal slag should be handed to customers, which would contribute to reducing the production cost of crude steel and at the end to the approaching of steel production process toward principles of the circular economy.