Buxton Operation
Limestone is brought from the quarry and tipped by the trucks into a large primary crusher. This 10 million piece of machinery, installed in 1999, works on the gyratory principle, and is capable of crushing up to 3,000 tonnes an hour.
A complex series of conveyor belts then carry the partly crushed rock to the secondary crushing unit which further reduces the stone and it is then screened into a wide range of different sizes from 125mm kiln stone down to dust.
Some of the stone is washed at this point to remove any clay material. The washings are used in the manufacture of cement.
The processed stone is stored in silos and stockpiles prior to dispatch by rail and road or use in downstream processes.
Lime Production
Th e high purity stone is transferred by conveyers to the lime kilns at Tunstead and by rail to the kilns at Hindlow site.
Buxton Lime operates three different types of kiln at its Tunstead and Hindlow sites in which limestone is burnt at very high temperatures - 1,100C to 1,300C, inducing a chemical reaction that creates quicklime. This enables the manufacture of a wide range of lump and ground quicklime products - the CALBUX range.
Two Maerz kilns, located at Hindlow, are supplied with limestone by rail from Tunstead. The limestone size used by these kilns is 90mm to 125mm. The Maerz kilns have two inter-connected, vertical shafts which are fired in sequence to achieve excellent energy efficiency. They are fuelled by natural gas and produce high reactivity and high purity quicklime which is used in industrial effluent treatment, domestic sewage treatment, manufacture of aerated concrete blocks, steelmaking and soil stabilisation.
Two rotary kilns at Tunstead are fed with stone in sizes ranging from 15mm to 40mm and are fuelled by a combination of coal and petroleum coke or natural gas. They produce high purity quicklime used for the manufacture of low-carbon steel, fibreglass and healthcare products.
Eight shaft kilns at Tunstead, which have recently undergone a 6 million refurbishment programme, use limestone of 90mm to 125mm size and are fuelled by natural gas. These produce medium reactivity quicklime which is used in a number of industrial processes including the manufacture of iron and steel, and aerated concrete blocks.
Quicklime from the kilns is also processed into hydrated lime. Buxton Lime operates the largest hydrate production facility in the UK producing its famous range of Limbux products. These arewidely used in construction, chemicals manufacturing, the treatment of drinking water and effluent neutralisation.
Buxton Lime has recently developed a new facility that produces a milk of lime which, unlike normal lime slurries, can be handled like a liquid. Called Kalic it is produced in a patented plant at Tunstead and is used for drinking water treatment and effluent neutralisation.
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