Reduction of Gaseous Emissions by Applying a Spray-Scrubber-Based Process for Cyanide Compound Reduction in Blast Furnace Gas

The reduction of hazardous air pollutants and greenhouse gas emissions is increasingly required by steelworks. The purpose of this study is the definition of an additional blast furnace gas treatment when it is burned in hot blast stoves or in other users such as power plants. It was found that reducing cyanide in blast furnace gas through a spray-scrubber reduces NOx at the chimney, enabling the increase of hot blast temperature and consequently CO2 emission reduction. An H2O2-based gas washing water treatment was also investigated to reduce cyanide content before water recirculation/purge. Simulation tools, laboratory tests, and in-field measurement campaigns were used to prove process effectiveness in reducing cyanides both in blast furnace gas and in used washing water.