Lime water uses

Because it is so readily made by heating limestone, lime must have been known from the earliest times, and all the early civilizations used it in building mortars and as a stabilizer in mud renders and floors. In a flare kiln, a bottom layer of coal was built up and the kiln above filled solely with chalk. The fire was alight for several lime water uses, and then the entire kiln was emptied of the lime.

In a draw kiln, usually a stone structure, the chalk or limestone was layered with wood, coal or coke and lit. As it burnt through, lime was extracted from the bottom of the kiln, through the draw hole. Further layers of stone and fuel were added to the top. Successive dome-shaped layers of limestone and wood or coal were built up in the kiln on grate bars across the eye. When loading was complete, the kiln was kindled at the bottom, and the fire gradually spread upwards through the charge. When burnt through, the lime was cooled and raked out through the base.

Fine ash dropped out and was rejected with the “riddlings”. Only lump stone could be used, because the charge needed to “breathe” during firing. This also limited the size of kilns and explains why kilns were all much the same size. Above a certain diameter, the half-burned charge would be likely to collapse under its own weight, extinguishing the fire. 30 tonnes of lime in a batch. Lime production was sometimes carried out on an industrial scale. Sets of seven kilns were common.

A loading gang and an unloading gang would work the kilns in rotation through the week. A rarely used kiln was known as a “lazy kiln”. The large kiln at Crindledykes near Haydon Bridge, Northumbria, was one of more than 300 in the county. It was unique to the area in having four draw arches to a single pot. As production was cut back, the two side arches were blocked up, but were restored in 1989 by English Heritage. The development of the national rail network made the local small-scale kilns increasingly unprofitable, and they gradually died out through the 19th century.

They were replaced by larger industrial plants. At the same time, new uses for lime in the chemical, steel and sugar industries led to large-scale plants. 1842 survives as part of the Black Country Living Museum which opened in 1976, although the kilns were last used during the 1920s. A preserved lime kiln in Burgess Park, London. A large limekiln at Broadstone, Beith, Ayrshire. The Annery kiln in Devon, England. Large 19th-century single limekiln at Crindledykes near Housesteads Northumbria.

Dumbarton castle in 1800 and functioning lime kiln with smoke in the foreground. In the late 19th and early 20th centuries the town of Waratah in Gippsland, Victoria, Australia produced a majority of the quicklime used in the city of Melbourne as well as around other parts of Gippsland. A lime kiln also existed in Wool Bay, South Australia. This section does not cite any sources. The key to development in efficiency was the invention of continuous kilns, avoiding the wasteful heat-up and cool-down cycles of the batch kilns. The fuel is injected part-way up the shaft, producing maximum temperature at this point. C, where de-carbonation begins, and proceeds progressively faster as the temperature rises.

Below the burner, the hot lime transfers heat to, and is cooled by, the combustion air. A mechanical grate withdraws the lime at the bottom. These typically consist of a pair of shafts, operated alternately. First, when shaft A is the “primary” and B the “secondary” shaft, the combustion air is added from the top of shaft A, while fuel somewhat below via burner lances. The hot gases pass downward, cross to shaft B via the so-called “channel” and pass upward to exhaust of shaft B. These contain a concentric internal cylinder.

This gathers pre-heated air from the cooling zone, which is then used to pressurize the middle annular zone of the kiln. Air spreading outward from the pressurized zone causes counter-current flow upwards, and co-current flow downwards. This again produces a long, relatively cool calcining zone. Fuel consumption is in 4 to 4. Rotary kilns started to be used for lime manufacture at the start of the 20th century and now account for a large proportion of new installations if energy costs are less important.

The early use of simple rotary kilns had the advantages that a much wider range of limestone size could be used, from fines upwards, and undesirable elements such as sulfur can be removed. All the above kiln designs produce exhaust gas that carries an appreciable amount of dust. Equipment is installed to trap this dust, typically in the form of electrostatic precipitators or bag filters. The lime industry is a significant carbon dioxide emitter. CO2 is later re-absorbed as the mortar goes off. This additional input is the equivalent of around 20 kg CO2 per ton if the electricity is coal-generated. You can help by adding to it.