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| Lime uses - A-Z applications of lime | |||
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Incineration: The continuing demand for power has resulted in an increase in the burning of fossil fuels. Many such fuels contain sulphur and the resultant emissions into the atmosphere are the principal cause of acid rain. Other sources of acid rain can be incinerators whether they burn municipal or industrial waste, clinical waste, animal carcasses or natural fuels. Almost all incinerators around the world have utilised lime as a means of removing harmful gases for many years and proved lime to be cost effective, efficient and sustainable. Lime is sprayed into the flue gas stream in the form of a dry powder or as a suspension in water. It then reacts with the pollutants to form an insoluble salt which is easy to dispose of. In the case of desulphurisation it is possible to produce quality gypsum (calcium sulphate) which can be used as a raw material in plaster or plasterboard. Iron and steel manufacture: In many countries, lime is used more for iron and steel making than for construction and building. Most of the lime used is for fluxing impurities in the basic oxygen steelmaking (BOS) process. Lime is also used in similar quantities in the following:
In fact, the BOS process replaced the Bessemer and open hearth steelmaking processes during the 1960’s and caused some major changes in both the steel and lime industries. The process is now used for 70% of the worlds steel production, with the remainder being in electric arc furnaces (EAF). Please refer to the Technical Section for more detailed information. Leather tanning: Hydrated lime helps to de-hair and "plump" hides before the tanning process is completed. Our soluble bag technology helps to reduce the effort associated with dosing lime into the washing drums. Lime Concrete: Lime concrete or "limecrete" is made by mixing controlled amounts of sand, aggregate, binder and water. Portland Cement is normally used as the binder, although nowadays hydraulic lime or hydrated lime plus a pozzolan can also be used. Limewash: Limewash is a traditional form of paint, used for the internal decoration of buildings with solid walls but without damp-proof courses. The moisture content of such walls is frequently high and varies with the seasons, meaning any wall decoration has to be porous. Limewash is also widely used in agricultural buildings due to its mild germicidal qualities coupled with its ease of application and relatively low cost. In addition, it has also been recommended by the Building Research Establishment (BRE) for use on bituminous surfaces, such as flat roofs to reduce radiant heat absorption from sunlight. Mortar:
The benefits of using lime and lime-cement mortars can be divided into two categories; ‘soft’ and ‘hard’ characteristics. They are as follows: Soft characteristics:
Hard characteristics:
Motor oil additives: Certain oil additives (including those used for motor vehicles) are produced by reacting hydrated limes with alkyl phenates or organic sulfonates. The resulting calcium soaps act as wear inhibitors, helping to reduce sludge build up and neutralise acidity from products of combustion. Paper manufacture: By using the lime cycle, we can increase the purity and consequently the brightness of a calcium carbonate by calcining, hydrating and then re-carbonating back to calcium carbonate. This process is used to make fillers and coating products which are used within the paper industry. The caustic properties of hydrated lime are used in the sulphate process during the manufacture of paper and pulp. About 250kg of quicklime per tonne of pulp are required for causticisation. Plaster: Internal plastering is used to cover up differences in level and to provide a surface which is suitable for the final decorative finish. Until the late 1800’s, internal plasters were predominantly lime based until the advantages of gypsum and cement became apparent. These binders gave faster setting and higher crushing strengths than the traditional lime plasters. It was subsequently found however, that the use of lime gauged with cement or gypsum, to obtain the required setting time and strength, improved both the handling characteristics and the durability of plaster. Other benefits are described as follows:
In general the benefits raised from the addition of lime in the plaster, far outweigh the small increase in raw material costs. Plastics: Quicklime reacts with any free water present to form hydrated lime. This removes water from the system and can be useful when dealing with products that are heated during the manufacturing process, such as plastic. When making plastic, if any potential water is not removed then steam bubbles may occur in the finished product, which can affect its strength and appearance. Quicklime is therefore often used in PVC and rubber manufacturing processes.
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Similar to the production of concrete and plasters, lime was the initial ingredient that was slowly replaced by Portland Cement that proved to be more beneficial due to its consistency and rapid development of strength. These cement-sand mortars however, proved to be almost too strong for most purposes, and the introduction of cement-lime mixes were proposed in the late 1800’s. This mix provided an even more efficient mix possessing both good ‘soft’ properties as well as controlled strength. 
The compressive strength of lime-cement mortars can be adjusted to the required level by the selection of the mix design.Please refer to the Technical Section for more detailed information. |
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