A feasibility study of using carbon black as a substitute to coal in cement industry

Cement factories traditionally use coal as an energy source in cement kilns since coal gives the high temperature that is required. Cement manufacturing is an energy intensive process. The extensive use of coal in kilns makes cement factories sensitive to rising prices of fossil fuels, and so an alternative fuel is needed to reduce fuel costs. This research investigated the utilisation of carbon black as fuel. The carbon black used was a by-product of a pyrolysis process. The process converts old tires into heavy crude oil and carbon black. We added carbon black to coal at the ratios of 0, 1.5, 3 and 5% by mass. The mixed fuel was used in a kiln which produces clinker cement. Then the final cement was produced from the clinker cement. The effects of the fuels on the clinker cement and cement were tested and the cost saving was studied.We found that the fuels did not affect product quality. Clinker cement and cement composition tests were made to quantify the values of C3S, C2S, C3S and C4AF and the compositions were found to be in acceptable ranges. Two physical tests used on the product cement were the setting times and compression tests. The initial and final setting times were within standards. Compression tests were made on samples with setting durations of 1, 3, 7 and 28 days. We learned that by adding carbon black into coal as a co-combustion fuel, we achieved 1–3% saving of fuel cost compared to the regular fuel.

► The project aimed to use carbon black to partially replace coal in cement industry. ► Carbon black added to coal at the ratios of 0, 1.5, 3 and 5% by mass. ► Properties of clinker cement and cement were compared with standard. ► Carbon black can be used and provides fuel cost saving of 1–3%. ► Clinker cement and cement composition tests were found to be in acceptable ranges.