No abstract

No abstract

Increasing concentration of atmospheric green house gases such as carbon dioxide (CO 2 ) that traps solar energy within the atmosphere are being investigated in connection with the warming of the planet and changes in climatic conditions. Carbon dioxide emitted from point sources plays major role for climate change. The steel industry is one of the largest energy consuming manufacturing sectors accounting for 3-5% of global carbon dioxide emissions. Mineral carbonation, involving the carbonation of the calcium and magnesium oxides in the steel slag fixes the carbon dioxide in the industrial waste. The process parametric studies are presented by varying the particle size, stirrer speed, temperature and pressures. The maximum carbonation efficiency obtained was in the range of 35-40% by direct carbonation method. Similarly results using catalysts such as acetic acid, ammonium chloride for the indirect carbonation method with carbon dioxide as well as flue gas are also presented. It is observed that the maximum carbonation efficiency is in the range of 85-97% with carbon dioxide and 50-55% with flue gases. The carbonated steel materials are proposed to utilize for the development of artificial reefs. Initial studies on the test blocks immersed in sea water are also discussed.

Increase in the concentration of carbon dioxide (CO 2 ) in the atmosphere is being attributed to the adverse effects such as warming of the planet; increase in the sea level; variation in the atmospheric and ocean circulation patterns; snow cover variation; and, sea ice extent. One of the common approaches followed in the mitigation efforts is the study on the reduction of the emissions of CO 2 from the major point sources such as coal fired power plants, steel plants, cement industries. Direct injection of the carbon dioxide into the deep oceans, mineral carbonation applications, in situ replacement of the gas hydrate into the carbon dioxide hydrates, micro algal sequestration and iron fertilization are some of the ocean sequestration options studied in the literature. Present chapter studies the feasibility of different ocean sequestration methods in comparison with the technological requirements for the realization of these methods.The relative merits of the methods, the technological challenges, ecological and environmental issues needing detailed studies for the application are discussed in this chapter. The experiments conducted on the mineral carbonation of industrial wastes such as steel slag using direct and indirect methods are discussed, considering the Linz-Donawitz converter slag. The carbonation efficiency for different conditions is compared and the structure of the resulting materials is analyzed. The prospective applications for coastal protective measures and artificial reef growth and the state of the art in similar applications using the concrete structure are discussed. The chapter discusses in detail the energy requirements in mineral carbonation methodology using the steel slag.