A Pre-Assessment related to Refractory Waste Management in Sweden : Pre-study of the performance of MgO-C bricks made from recycled MgO-C refractory materials for use in steel production

Sammanfattning: Steel industries consume refractory materials on a large scale. High temperature resistant refractory materials are essential for linings of the steelmaking vessels, to protect them from corrosive environments, high temperatures, molten steels and slags during transportation and steelmaking operations. Furthermore, with the increasing demand in steel production the usage of refractory materials has substantially increased, resulting in an increasing demand for refractory raw materials. However, with the hike in prices and abundancy for raw materials there is a need for recycling and reusing of spent refractory materials, which are otherwise sent to landfill. Nowadays the environmental as well as economic aspect regarding the recycling of spent refractories are of interest for the steel industries for achieving a solution towards zero waste. Several projects have been launched to investigate and generate new ideas with different ways to recycle refractory materials, but there is much more research and planning that needs to be done in order to find a large scale solution towards achieving zero waste. One of the simplest solutions to avoid landfilling of spent refractory is to introduce and manage a good sorting of the breakout scrap refractory, which can later be recycled or reused depending on their condition. The thesis work was carried out in collaboration of KTH – The Royal Institute of Technology/ Stockholm/ Sweden and Jernkontoret – The Swedish Steelmaking Association / Stockholm / Sweden. The work includes a collection of information regarding the current refractory waste management situation within some of the Swedish steel producers as Ovako AB, Uddeholm AB and SSAB. The information were collected on the basis of their refractory usage and practises. The thesis as well provides some suggestions for recycling and reusing of spent refractory waste materials collected from literature. Additionally some experimental work was carried out on whether an MgO-C refractory brick made of recycled materials can perform similarly against slag as a brick made from virgin materials. Experimental corrosion trials with one industrial slag composition were carried out using a hot-finger test apparatus for bricks with different amounts of recycling content in comparison to a brick made of virgin materials. After experiments, the samples were analysed using a Light Optical Microscope (LOM). A similar performance of all bricks against the slag composition was observed. Additional laboratory tests with different slag compositions, holding times and stirring rates are required to reach more profound conclusions. Industrial trials are essential with bricks containing recycled raw materials to reach a final performance status.