Natural and enhanced carbonation of lime in its different applications: a review

Abstract

Lime is a product derived from the thermal decomposition of limestone (mainly calcium carbonate, CaCO 3 ) into quicklime (CaO) and carbon dioxide (CO 2 ), also called calcination. Controlled reaction with water is used to manufacture hydrated lime (Ca(OH) 2 ) products. Lime is used in a wide variety of applications: metals industry, construction materials sector, civil engineering, environmental protection, agriculture, and chemical industry. Lime production is one of the sources of anthropogenic CO 2 emissions resulting in global warming and ocean acidification. However, a proportion of the CO 2 emitted during the calcination is reabsorbed by the lime during the product life within its different applications. This process called carbonation is thermodynamically favoured because it is exothermal. It allows permanent CO 2 storage in a stable product since the lime combines with gaseous CO 2 reforming CaCO 3 . This paper reports a comprehensive literature review on the carbonation potential of lime in different applications. The total carbonation potential is assessed as carbonation rate, i.e. the ratio between the CO 2 reabsorbed through carbonation during the operational life of lime and the CO 2 emitted during limestone calcination. This study provided preliminary evidence that, based on the current EU market, on average 23-33% of lime process emissions are carbonated during the use phase. Carbonation over time is also analysed for the lime applications where information is available. For three applications, namely water, flue gas cleaning and pulp and paper, the carbonation reaction is instantaneous. Up to 22% of the calcination emissions are absorbed within five years based on the current EU market.

Reducing the Carbon Footprint of Bituminous Composites Using Amine-Impregnated Zeolite

“…Carbon dioxide (CO 2 ) is the main byproduct of the calcination process, in which limestone [mostly calcium carbonate (CaCO 3 )] is heated to produce quicklime (CaO), eq . Water is then added to quicklime to produce hydrated lime (Ca­(OH) 2 ), eq : …”

“…Although the CO 2 emitted during the calcination process is reabsorbed by the lime during its service life, just 23–33% of the emissions are reabsorbed during the use phase within 5 years . It is worth noting that the application of hydrated lime is not limited to the asphalt industry.…”

“…Since the amount of lime used in producing an asphalt mixture is 1% by the weight of the mixture, an estimated 17.22 tons of CO 2 would be generated per lane mile of the pavement. It has been reported that on average, 33% of the CO 2 emitted during the production of lime is captured during the carbonation process . This leaves about 67%, which is nearly 12 tons of CO 2 per lane mile.…”

“…Although the CO 2 emitted during the calcination process is reabsorbed by the lime during its service life, just 23−33% of the emissions are reabsorbed during the use phase within 5 years. 17 It is worth noting that the application of hydrated lime is not limited to the asphalt industry. As a multifunctional material, hydrated lime is used in many processes, from steel manufacturing to construction and building foundations and as a purifying agent in many industrial environments.…”

“…It has been reported that on average, 33% of the CO 2 emitted during the production of lime is captured during the carbonation process. 17 This leaves about 67%, which is nearly 12 tons of CO 2 per lane mile. Considering the significant carbon footprint of lime, as well as the asphalt industry's vision toward net zero carbon emissions by 2050, 38 there is a need for sustainable low-carbon alternatives.…”