When buildings reach the end of their lives, lime is soft enough to allow the masonry to be taken apart and reused. Cement will potentially add to landfill problems for generations to come. Last but not least, lime's ability to control moisture means it is compatible with low-energy, sustainable materials, such as water reed, straw, hemp, timber and clay. The appropriate use of lime, therefore, can assist us both in conserving our past and creating buildings that are more green-friendly in the future.
This article is more than 14 years old. Carbon emissions could be cut if we used this ancient building material more widely, says Douglas Kent. Topics Environment Opinion Climate crisis comment.
Reuse this content. Acids in acid rain promote the dissolution of calcium carbonate by reacting with the carbonate anion. This produces a solution of bicarbonate. Because surface waters are in equilibrium with atmospheric carbon dioxide there is a constant concentration of carbonic acid, H 2 CO 3 , in the water. The presence of limestone and other calcium carbonate rock in lakes and streams helps to maintain a constant pH because the minerals react with the excess acid.
Lime is used to remove these acidic pollutants from the flue gas as part of environmental management systems to minimise the impact of these activities on air quality. The use of lime in all of the three main flue gas treatment processes - dry, semi-dry and wet - shows its flexibility and adaptability in its worldwide application for flue gas treatment.
Calcium oxide CaO - quicklime or calcium hydroxide Ca OH 2 - hydrated lime , and calcium carbonate CaCO 3 - limestone or chalk can each be used to neutralise the acidic gases and remove sulfur dioxide from flue gases.
This helps to ensure that plants comply with both local and international environmental legislation for their emissions. Together with the specialist flue gas treatment equipment technologies, lime is the most cost effective and versatile alkali that can be used for this kind of treatment, with less dosage and less waste production compared with other reagents.
The number of EfW plants in the UK has seen a marked increase since and this trend is expected to continue until at least as government policy is to target reduction in landfilling of household and commercial waste, a contributor of environmentally harmful methane gas and to encourage more recycling and use of EfW.
This policy development and growth of flue gas treatment FGT is also seen in many other countries around the world. Lime products can therefore provide a cost effective, efficient solution to the treatment of flue gases generated from the energy recovery process, which reduces the waste volumes sent to landfill.
A variety of flue gas abatement techniques have now been designed to suit particular applications, some of which are described below. Hydrated lime is fluidised in air and injected straight into the exhaust ducting.
The most common neutralisation reactions are as follows:.
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