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Production of carbon negative precipitated calcium carbonate from waste concrete
Author(s) -
Van der Zee Sterling,
Zeman Frank
Publication year - 2016
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.22619
Subject(s) - carbonation , calcium carbonate , alkalinity , waste management , carbon dioxide , chemistry , pulp and paper industry , environmental science , engineering , organic chemistry
Mineral carbonation can contribute to climate change mitigation through the production of synthetic limestone (CaCO 3 ) from calcium silicate minerals and gaseous CO 2 . Some carbonates, such as Precipitated Calcium Carbonate (PCC), have industrial applications and may provide sufficient economic incentive for sequestering CO 2 should the product be a marketable commodity. Cement is a suitable source of calcium and can be recovered from waste concrete. The production of cement accounts for 9.5 % of global CO 2 emissions, however up to 50 % of the manufacturing emissions can be mitigated at the end of the materials service life through mineral carbonation. The objective here is to sequester CO 2 through the production of PCC via the recovery and carbonation of calcium from waste cement. The calcium is suitable for mineral carbonation and can be effectively leached using an acid (e.g. HCl). When calcium is completely leached, the solution will be slightly acidic and contain impurities such as iron and silica. The impurities can be removed by adding alkalinity prior to CaCO 3 precipitation, via reaction with Na 2 CO 3 in a separate reactor. The Na 2 CO 3 is produced by the absorption of CO 2 using NaOH, while the resulting NaCl solution is recycled via bipolar membrane electrodialysis. Overall transportation emissions and costs are reduced and the process could enhance current waste concrete recycling practices. Furthermore, the low carbon intensity of electricity generation in Eastern Canada allows for capture of 444 kg CO 2 per tonne of PCC.