Carbon dioxide sequestering potential of ultramafic rocks
Fossil fuels continue to provide major sources of energy to the modern world even though global emissions of CO{sub 2} are presently at levels of {ge}19 Gt/y. Future anti-pollution measures may include sequestering of waste CO{sub 2} as magnesite (MgCO{sub 3}) by processing ultramafic rocks to obtain reactable Mg. Common ultramafic rocks react easily with Hcl to form MgCl{sub 2} which is hydrolyzed to form Mg(OH){sub 2}. CO{sub 2} gas is reacted with Mg(OH){sub 2} to produce thermodynamically stable magnesite. Huge ultramafic deposits consisting of relatively pure Mg-rich silicates exist throughout much of the world in ophiolites and layered intrusions. Peridotites (especially dunites) and serpentinites comprise the best ores because they contain the most Mg by weight and are relatively reactive to hot acids such as HCl. Although mining such deposits on large scales would have environmental impacts, the sequestering process would provide Fe, Cr, Ni, and other metals as by-products and could dispose of existing waste (white) asbestos. Small ultramafic bodies ({approximately} km{sup 3}) can potentially sequester about 1 Gt of CO{sub 2} or about 20% of annual USA emissions. A single large deposit of dunite ({approximately}30 km{sup 3}) could dispose of about 20 y of current USA CO{sub 2} emissions. The cost and environmental impact of mining these deposits must be weighed against the increased costs of energy and benefits to the atmosphere and climate.
- Research Organization:
- Los Alamos National Lab., NM (US)
- OSTI ID:
- 20012966
- Country of Publication:
- United States
- Language:
- English
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