milling

Village milling

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Traditional milling

Hand pounding of paddy in a mortar with a pestle is the traditional milling process in remote villages. Pounding the paddy induces upward and downward forces on grain against grain that removes the husk and bran layers. The pounding also breaks up fissured grain. The final cleaning is by winnowing in a woven bamboo tray. The winnowing process to separate unmilled paddy grain is an art.
pounding

 


Village rice mills

Village-type rice mills can be found in rural communities and are used for service milling paddy of farmers for home consumption.

Single pass, single stage mill

The single pass rice mill is an adaptation of the "Engleberg" coffee huller from the United States, modified for milling rice. In earlier days this type of rice mill was very popular in most rice-growing countries.  It is still the mainstay technology for milling parboiled paddy in Bangladesh, and in many African countries. The  "iron hullers", or "single pass mills" which all refer to the same mill are notorious for breaking the paddy grain. Because of the high breakage, the total milled rice recovery is 53-55%, and head rice recovery is in the order of 30% of the milled rice. The fine brokens are mixed with the bran and the ground rice hull. This by-product is used for animal feed. In many rural areas, Engleberg mills are used for custom milling the rice requirements of households. The bran produced is left to the miller as the milling fee. The poor performance of the Engleberg mill has led governments to discourage its use and has limited further proliferation. In many Asian countries, Engleberg mills can no longer be licensed to operate as service or commercial mills.

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Single pass, two stage mills

These are small capacity 2-stage rice mills, 0.5 to 1 ton per hour paddy input. They are also used for custom milling services in the rural areas. A typical compact rice mill consists of a 6-inch diameter x 6-inch wide rubber roller husker, and a friction whitener. The friction whitener has a very similar design configuration as the Engleberg except that is has no husking knife.  The milling performance of the compact rice mill is superior to the single pass Engleberg huller. Milling recoveries are normally above 60%.

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