Abstract
Waste heat recovery from high temperature slags represents the latest potential way to remarkably reduce the energy consumption and CO2 emissions of the steel industry. The molten slags, in the temperature range of 1723–1923 K, carry large amounts of high quality energy. However, the heat recovery from slags faces several fundamental challenges, including their low thermal conductivity, inside crystallization, and discontinuous availability. During past decades, various chemical methods have been exploited and performed including methane reforming, coal and biomass gasification, and direct compositional modification and utilization of slags. These methods effectively meet the challenges mentioned before and help integrate the steel industry with other industrial sectors. During the heat recovery using chemical methods, slags can act as not only heat carriers but also as catalysts and reactants, which expands the field of utilization of slags. Fuel gas production using the waste heat accounts for the main R&D trend, through which the thermal heat in the slag could be transformed into high quality chemical energy in the fuel gas. Moreover, these chemical methods should be extended to an industrial scale to realize their commercial application, which is the only way by which the substantial energy in the slags could be extracted, i.e., amounting to 16 million tons of standard coal in China.
Highlights
The steel industry is an energy-intensive and CO2-intensive industry, consuming around 9% of total anthropogenic energy [1] and emitting one quarter of all industrial CO2 into the atmosphere in theWorld [2]
Cai et al [12] have reported that in China the waste heat recovery ratio of high temperature slags is less than 2%, so there is a great potential for waste heat recovery
Because of the low thermal conductivity, the slags should be granulated into small particles with diameters of 3–5 mm [7,8] to extract the thermal heat and the heat transfer medium should flowed through with a larger rate; the temperature of the medium could not reach a high level and subsequently this explains the low waste heat recovery efficiency achieved through physical methods [7,8,19]
Summary
The steel industry is an energy-intensive and CO2-intensive industry, consuming around 9% of total anthropogenic energy [1] and emitting one quarter of all industrial CO2 into the atmosphere in the. For typical iron ore grades (60% to 66% iron), a blast furnace normally produces about 0.30 ton of blast furnace slag (BFS) per ton of pig iron produced and a steel furnace typically produces 0.10–0.15 ton of steel slag (SS) per ton of crude steel [10] Using these ratios and data, it can be estimated that China’s production of BFS and SS in 2012 was around 200 million tons and 110 million tons, respectively. The chemical compositions of the slags were modified by various additives and the material resources were directly recycled for extraction of valuable elements or slag wool production [19] These foregoing chemical methods provided various possibilities of heat recovery from hot slags. The object of this paper is to summarize the fundamental constraints of heat recovery from high temperature slags and review these chemical methods exploited during past decades especially from viewpoint of thermodynamics possibility and kinetic mechanism and to forecast possible promising routes in the future
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
