Portland cement exhaust characterization and its potential use in mineral carbon sequestration: case study — artisanal kiln output

• Published in: Arabian journal of geosciences 2022-02, Vol.15 (3), Article 308
• Main Authors: Senzani, Freeman Elther David, Mulaba-Bafubiandi, Antoine Floribert
• Format: Article
• Language: English
• Subjects: 1st CAJG 2018; Acid rain; Ammonia; Aqueous solutions; Argon; Carbon capture and storage; Carbon dioxide; Carbon monoxide; Carbon sequestration; Carbonation; Cement; Clinker; Coal; Concrete; Earth and Environmental Science; Earth science; Earth Sciences; Emissions; Energy; Exhausts; Gases; Heat; Kilns; pH effects; Portland cement; Portland cements; Prototypes; Sulfur; Sulfur dioxide; Sulphur; Sulphur dioxide; Water vapor; Water vapour
• ISSN: 1866-7511; 1866-7538
• DOI: 10.1007/s12517-021-09337-9

Modern commercial Portland cement manufacturing produces, in its exhausts, significant amounts of carbon dioxide, carbon monoxide, sulphur dioxide, oxygen, nitrogen, water vapour and argon. The amount of gas for each tonne of clinker produced is estimated to be a total of 1.7961 tonnes, while the volumes are 14.87 m 3 at 300 °C, and 22.66 m 3 at 600 °C, while the heat energy available for potential downstream use is 1272 MJ and 1 938 MJ, also at the same respective temperatures. An ongoing study has designed a Portland clinker kiln, specially customized for use at an artisanal scale. For purposes of minimizing the input of greenhouse and acid rain gases during its use, it is thought necessary to investigate ways of capturing the carbon dioxide. After reviewing different techniques, the indirect aqueous mineral carbonation approach, with pH reversal using NH 4 HSO 4 and NH 3 .H 2 O, was adopted. If the extraction fluid tank is heated up to 140 °C, the heat energy required is 600 MJ. It is 727 MJ for the carbonation tank for a tonne of clinker. For the artisanal kiln, the heat energy contained in the gas emissions was estimated, with the view to using it for carbon capture and sequestration. The first approach was for an idealized situation using local materials and coal fuel. This showed that for a tonne of Portland clinker, the emitted CO 2 , SO 2 and moisture totals 5768 kg, while the potential heat energy accompanying the emissions would be 2197 MJ and 5121 MJ at 300 °C and 600 °C, respectively, per tonne of clinker. Finally, measurements during a clinkering cycle, using a prototype version of the artisanal kiln showed emission of 11,528 kg per tonne of Portland clinker. This potentially carries a total of 4330 MJ at 300 °C and 10,102 MJ at 600 °C. A three-phase, NH 3 -based, pH-swing carbon capture and sequestration approach would require 600 MJ, while the second will require 727 MJ, to heat the aqueous solutions to 140 °C. There is, therefore, potential for utilization of the heat contained in the emissions to partly drive the carbon capture and sequestration at the artisanal clinkering set up envisaged in this series of studies.