The most important and the most frequently used plastics are polyethylene (PE) and polypropylene (PP). They are characterised with high heating values (approximately 40 MJ/kg). Moreover, their chemical composition, based mainly on carbon and hydrogen, allows to use them in industrial processes. One of the methods of utilisation of plastic waste can be its use in the metallurgical industry. This paper presents results of thermal decomposition of waste PE/PP. Chemical and thermal analysis (TG) of studied wastes was carried out. Evolved gaseous products from the decomposition of wastes were indentified using mass spectrometry (TG-MS). This paper also presents an application of plastic wastes as supplemental fuel in blast furnace processes (as a substitute for coke) and as an addition in processes of coking coal.

Dust generated at an electric arc furnace during steel production industry is still not a solved problem. Electric arc furnace dust (EAF) is a hazardous solid waste. Sintering of well-prepared briquetted mixtures in a shaft furnace is one of possible methods of EAFD utilisation. Simultaneously some metal oxides from exhaust gases can be separated. In this way, various metals are obtained, particularly zinc is recovered. As a result, zinc-free briquettes are received with high iron content which can be used in the steelmaking process. The purpose of the research was selecting the appropriate chemical composition of briquettes of the required strength and coke content necessary for the reduction of zinc oxide in a shaft furnace. Based on the results of the research the composition of the briquettes was selected. The best binder hydrated lime and sugar molasses and the range of proper moisture of mixture to receive briquettes of high mechanical strength were also chosen and tested. Additionally, in order to determine the thermal stability for the selected mixtures for briquetting thermal analysis was performed. A technological line of briquetting was developed to apply in a steelworks.

The paper aims to confirm the syngas application as a reburning fuel to reduce e.g. NO emission during natural gas combustion. The main aim of this modelling work was to predict pollutants generated in the exhaust gases and to indicate the influence of the syngas on the natural gas combustion process. The effect of residence time of fuel-air mixture was also been performed. Calculations were made with CHEMIKN-PRO for reburning process using syngas. The boundary conditions of the reburning process were based on experimental investigations. The addition of 5, 10, 15 and 19% of reburning fuel into natural gas combustion was studied. The effects of 0.001 to 10 s of residence time and the addition of 5, 10, and 15% of syngas on combustion products were determined. The performed numerical tests confirmed that co-combustion of the natural gas with syngas (obtained from sewage sludge gasification) in the reburning process is an efficient method of NOx reduction by c.a. 50%. Syngas produced from sewage sludge can be utilised as a reburning fuel.