Industrial Symbiosis is the part of Industrial Ecology that manages environmental and economic improvements through the exchange of materials, resources, utilities, and by-products between members of a network of companies, such as supply chains or technological clusters. The purpose of this article is to analyze the mutual exchange of materials that occur among a steelmaking plant, vendors, and other business partners in a network of industrial companies. The research object is a steelmaking plant of Brazil. Almost 100 % of the raw material of the steelmaking industry is metallic scrap originated from other industries. Likewise, the steelmaking industry routes almost 100 % of the waste to other companies provided there is commercial and logistical feasibility. Seven major companies form the network, but this study involves only three companies. The complete study involves the entire network. This study involves a steelmaking plant, that generates by-products (slag, electric arc furnace dust, mill scale, and zinc sludge) used by a cement plant and a zinc smelting plant as raw materials. The zinc smelting plant closes the loop of the circular economy, as the sludge serves as raw material for zinc ingots used by the steelmaking plant in the galvanization process of its wire rod manufacture. The study concluded that synergetic relationships of mutual interest are the main factor that drives the industrial symbiosis in the network. Environmental aspects are also relevant. Even existing mutual interest, industrial symbiosis strongly depends on external factors, like logistics and legal compliance. The companies must rely on intermediate transportation companies that usually have difficulties to comply with the legislation and rarely has competitive costs or high production scale.