The basic idea of carbon dioxide mineral sequestration is to transform minerals (mostly calcium or magnesium silicates) with CO₂ to (Ca or Mg-) carbonates. The most promising feedstock minerals are Olivine, Serpentine and Wollastonite. These silicates of Magnesium and Calcium react with CO₂ to form the corresponding carbonates and SiO₂. The decisive fact for these reactions is that all of them are exothermal which means that theoretically no energy is required for the reactions to proceed but could potentially even be gained. The resulting mineral carbonates are stable and abundant in nature anyways and could hence be disposed off without any considerable consequences.

The separated stream of carbon dioxide is transported to a mineral mining site where a chemical process scheme will be erected to convert the carbon dioxide with a mineral to the carbonates which then can be disposed off back in the mine. A variety of process pathways are described in literature for the mineral carbonation process.

Advantages of Mineral Sequestration

• Long Term Stability - Mineral carbonation is a natural process that is known to produce environmentally safe and stable material over geological time frames. The production of mineral carbonates insures a permanent fixation rather than temporary storage of the CO₂, thereby guaranteeing no legacy issues for future generations.
• Vast Capacity - Raw materials for binding the CO₂ exist in vast quantities across the globe. Readily accessible deposits exist in quantities that far exceed even the most optimistic estimate of coal reserves.
• Potential to be Economically Viable - The overall process is exothermic and, hence, has the potential to be economically viable. In addition, its potential to produce value-added by-products during the carbonation process may further compensate its costs. At a single site and scale that is consistent with current industrial practice, the process can handle the output of one to several large power plants. It is directly applicable to advanced power plants such as zero-emissions Vision 21 system configurations being developed by DOE’s Fossil Energy Program or to existing power plants, thereby providing an additional degree of flexibility for future implementation.

 

Disadvantages of Mineral Sequestration

• Carbonation plant must be at the site of the mine due to the large volumes of material required.
• Volumes increase upon carbonation so in order to store the newly formed carbonates back in the mine some terrain alteration will be necessary.
• Extensive mining operations necessary, which will have environmental impact.
• There is the potential for asbestos to be present in the mineral deposit.
• Must be able to deal with ore impurities.