British Lime Association - The Trade Association for the UK Lime Industry

	Lime uses - A-Z applications of lime
	Q - Z A-H I I-P I Q-Z
	Renders Restoration Sewage works Sludge treatment	Soil stabilisation Sugar processing Wildlife sanctuaries Wire drawing
	Renders External rendering mortars are used to enhance the appearance of buildings and to make the structure waterproof. Lime renders help by acting like a sponge, absorbing rainfall then allowing it to evaporate rather than soak into the wall. As with many lime applications, the use of lime was almost made redundant by the introduction of cement in the late 1800’s. However, it was discovered that excessively high cement contents caused problems and that the use of cement-lime mortars gave significant improvements in both the ‘soft’ and ‘hard’ characteristics. Overall renders and plasters can be applied to a variety of backgrounds including earth (which should nearly always be rendered), stone and brick. Lime based renders now offer the best performance possible, benefits include; vapour exchange, water resistance, elasticity, compatibility with all types of background and even eco friendliness. Top of page Restoration: Buildings pre 1900 would not have been built with cement (with few exceptions in the late 19th century) but with a lime mortar. Therefore in order to conserve these buildings it is essential to use similar materials when doing so. To introduce cement or cementitious mortar would cause decaying due to the difference in chemical composition of cement and inevitably result in irreversible damage. Lime mortars, lime plasters and renders and lime putty are therefore all used for the restoration of the UK and the majority of Europe’s built heritage. Download: Devonshire hospital Top of page Sewage works: Sewage generally consists of both domestic and trade effluent. It contains suspended solids, dissolved colloidal organic matter, nutrients (phosphate and ammonia) and even heavy metals (particularly from trade effluents). Lime products have been used extensively in the treatment of sewage for over one hundred years. Its roles have included the following: The adjustment of the pH of the incoming sewage. Coagulation and flocculation of the solids. Removal of metals and nutrients. Disinfection. Conditioning the sludge for agricultural use or as a landfill. Sewage treatment currently uses a combination of mechanical, biological and chemical processes to produce a discharge of the required standard at the lowest possible price. In most countries, the requirements for the discharged water is becoming more and more stringent, causing rapid changes in the industry which may well present huge opportunities for increased lime scales. Top of page Sludge treatment: A wide number of organic and inorganic sludges can be treated using quicklime or dolomitic lime to increase solids content. Biological sludge can be sanitised by the rise in temperature and pH obtained by adding these materials. Biosolids treatment up Advanced Treated is achievable with this method. Please refer to the Technical Section for more detailed information. Download: Strategic use of liquid lime in sludge treatment Top of page Soil stabilisation: Lime treatment for soils, often involves the use of quicklime, or slaked lime, either as powdered hydrated lime, or as milk of lime. The effect of adding lime to soils can be divided into three distinct stages; drying, modification, and stabilisation. Drying - occurs when quicklime is used. The quicklime hydrates, absorbing water and generating heat, which in turn causes some of the water to evaporate. Total water moisture loss can be up to double that required to hydrate the quicklime. The drying process occurs almost immediately with reactive quicklimes. Modification - occurs with both quick and slaked lime, which rapidly enter into the physio-chemical reactions with any clay minerals present. The resulting changes include ion exchange and can occur within 6 hours, dramatically reducing the plasticity of the soil but increasing its workability and improving its compaction characteristics. Stabilisation - is often a much slower, occurring overall several months it involves the reaction of lime with the siliceous and aluminous components of the soil. The addition of lime raises the pH of the soil to above 12, resulting in the formation of calcium silicates and aluminates. These are believed to form initially as gel, which coats the soil particles, and subsequently crystallises as calcium silicate/aluminate hydrates. Those hydrates are cementitious products, similar in composition to those found in cement paste. The resulting gain in strength is progressive. After the drying and modification stages, water is added to obtain required moisture content for consolidation. The soil is then compacted to reduce the level of air voids to no more than 5%, ensuring that the stabilisation reaction proceeds in the compacted state and results in a homogenous, impermeable and stable layer. The stabilised layer has a low and acceptable shrink-swell potential, and improved compressive, tensile and flexural strengths. It also reduces the susceptibility of the stabilised layer to frost damage. Please refer to the Technical Section for more detailed information. Top of page Sugar processing: Sugarbeet - The production of sugar from sugarbeet requires approximately 200kg of quick lime per tonne of sugar. The raw beet is washed and chopped and treated with hot water to extract the sugar. The sugar solution also contains dissolved, suspended and colloidal matter. The extract is initially treated with excess lime, which raises the pH and precipitates insoluble calcium salts of both organic and inorganic acids. Carbon Dioxide (CO₂) is then passed through the suspension to precipitate excess lime as calcium carbonate (CaCO₃). The precipitation process removes suspended and colloidal matter as a ‘carbonation sludge’ which is then removed by filtration. The filtrate is a solution of sugar and is recycled. Many sugarbeet processing plants operate their own lime kilns on site in order to produce the quick lime and CO₂ needed for the process. Sugarcane - ‘Slaked lime’ is used in the production and refining of sugar. Sugarcane is cut, shredded and treated with water to produce raw juice with a pH of 4 to 5. The juice is treated with lime to raise the pH and heated to approximately 70-75°C to destroy invertase and other enzymes. Roughly 2-5kg of hydrated lime is used per tonne of sugar produced. Sugar from other plants - Sugar is also extracted commercially from certain species of palm, from the sugar maple and from sweet sorghum. Lime is used to purify the extracts before evaporation. Top of page Wildlife sanctuaries: Old quarries are restored using inert waste. Restored land often maintains a higher level of biodiversity than the area did prior to quarrying. In fact, the majority of restored sites are now categorised as ‘National Nature Reserves’ of ‘Wildlife Sanctuaries.’ A number of old quarries also transform into shallow wetlands which provide habitats for a wide array of rare and endangered bird species. Over 700 Sites of Special Scientific Interest (SSSI’s) have been designated on former quarries, a large number of which were used to quarry limestone. Top of page Wire drawing: Hydrated lime suspensions or milk of lime is used to neutralise and coat wire after it is acid cleaned. This acts as a slip agent to reduce friction during the drawing process and helps protect the wire during storage. Top of page A-H I I-P I Q-Z