Feasibility analysis of biomass hydrochar injection for blast furnace

Abstract

Iron and steel production consumes a lot of fossil fuels, emits CO2 and discharges pollutants. Reducing CO2 emissions in the process of iron and steel production has become the key to achieve the goal of "carbon peak" and "carbon neutrality" for the iron and steel industry. Biomass as a product of plant photosynthesis, which has the characteristics of large yield, renewable and carbon neutral, is the only renewable carbon source with good storage and easy transportation characteristics. The efficient application of abundant biomass resources in iron-making with blast furnace has become the key to achieve green and sustainable development of iron and steel industry. However, biomass generally has the disadvantages of high moisture content, low fixed carbon content and calorific value, more harmful elements of alkali metals (K, Na) and poor crushing performance. Without carbonization treatment, it is difficult to meet the requirements for the process performance of fuel injection for blast furnace iron-making. The differences of pyrolysis and hydrothermal carbonization (HTC) technology principle was analyzed, and two type preparation technologies of biomass carbon and the basis performance and processing property of blast furnace injection was investigated. Results showed that the pyrolysis carbonization can remove the volatile in biomass, improve fixed carbon content and calorific value, but the ash and alkali metal elements will be enriched into biomass during pyrolysis. The content of ash and alkali metals in pyrolysis biomass was increased significantly, and the alkali metal content in four pyrolysis biomass was more than 1%, far above the standard for alkali metal content in coal with high basicity, which cannot meet the requirements of blast furnace injection. Hydrothermal carbonization could effectively remove volatile and dissolved mineral elements of biomass. Biomass hydrochar prepared had low content of ash and alkali metal, high fixed carbon and calorific value, high grindability and excellent combustion performance, which was met the requirement of blast furnace injection. The biomass HTC technology solves the restrictive problems of low biomass energy density, high content of harmful elements, and difficulties in grinding and injecting. The implementation for new technology of high quality carbon-neutral fuel for blast furnace injecting through the biomass HTC technology is beneficial to Baowu Group to achieve green and low-carbon iron-making.