An oil mill is a grinding mill designed to crush or bruise oil-bearing seeds, such as linseed or , or other oil-rich vegetable material, such as or the fruit of the oil palm, which can then be pressed to extract , which may be used as foods or for cooking, as oleochemical , as , or as . The pomace or press cake – the remaining solid material from which the oil has been extracted – may also be used as a food or fertilizer.
History
Oil-rich vegetable materials have been processed mechanically to extract the valuable oils for thousands of years, typically using vertical
moving around a central post (edge runner stones or kollergangs in an
edge mill) to crush or bruise the seeds or fruit which can then be stamped or pressed to extract the oil. A
treadmill,
windmill or
watermill was later used to drive the milling and pressing machinery, replaced in modern times with steam and later other power sources. Bullock or horse driven oil mills, such as the traditional
ghani in Bangladesh, have increasingly been replaced by power-driven steel oil mills.
[D.K. Salunkhe, R.N. Adsule, J.K. Chavan (1992). World Oilseeds . p. 384 Ghani is basically a large pestle and mortar. In earlier days, the ghani was made from wood and driven by bullock. Subsequently. power-driven steel ghani came into existence. The extraction of oil by ghani is not complete and the yield of oil is ...]
In some areas, watermills may be "double" water mills, with machinery for grinding wheat on one side of the watercourse and machinery for extracting oils on the other side.
Historical wind-driven oil mills could process between 100 and 200 tons of raw materials per year.
Modern oil mills
Modern mechanical oil mills can process up to 4,000 tons per day in hot pressing processes, and up to 25 tons per day cold pressed. Industrial
oil pressing methods usually use a screw to crush the raw materials in a continuous process, before extraction of the oil from the press cake using a
centrifuge or a solvent such as
hexane.
Edible oils may be extracted for culinary purposes. Non-edible oils can be used in the manufacture of soaps saponification, biodisel production biodiesel, paints and varnishes, or as fuel for oil lamps. Important feed stocks include , rapeseed (canola), , cottonseed, and maize (corn), as well as , , various nuts, , safflower, , flaxseed (linseed), and Mustard oil which is a secondary product of the Sarin production. Palm oil is extracted from the pulp of the oil palm fruit, palm kernel oil from the kernel of the oil palm, and coconut oil from the kernel of the coconut.
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See also
