Environmental evaluation of grey cast iron via life cycle assessment

Abstract

The metallurgy industry significantly influences the quality of its surrounding environment. This paper, therefore, focuses on creating a model of life cycle assessment (LCA) for a foundry producing grey cast-iron castings. The principles of a LCA are given in ISO 14040: 2006 and ISO 14044: 2006.The environmental impact of the production of one ton of ready grey cast-iron castings was quantified, and the significant components of the LCA model were identified. The Hronec foundry model is situated in Slovakia, and its average annual production is 6000 tons of grey cast-iron castings. The production consists of typical processes for melting metal in cupolas, including production of castings by pouring molten metal into single-use sand moulds and final finishing before dispatch.The SimaPro 8 and ReCiPe Endpoint (quality of ecosystem, human health and consumption of resources) methods were used to assess the environmental impact of the castings.The greatest overall negative environmental impact (74.1%) is caused by processes related to melting metal in the smeltery, with the greatest negative impact on the consumption of resources. An important component of the LCA and the company's contribution is the identification of recycled metal waste (iron and steel waste sort 258.598 kg/t, backspacing scarp 82.88 kg/t and metallic packaging waste 0.952 kg/t), which in the melting process, reduces the impact of smelting by 9.52%. The next important component of the LCA and the company's contribution is the recycling of waste cores (1204.92 kg/t) during the manufacture of moulds, which reduces the impact of moulding by 1.65%.The overall impact of the other main foundry processes on environmental quality was minimised using environmental measures in the foundry, particularly its technological methods. These methods focused on reducing the demand for raw materials and other materials, energy consumption, release of emissions to the atmosphere, water use, and creation and production of solid waste as well as increasing the quality of drained water. These findings directly indicate the importance of the environmental measures that are used in foundry production processes. This “cradle-to-gate” LCA study can therefore form the basis for further environmental analyses that will help to reduce the negative environmental impact of foundry production.