Abstract

Sorghum is the staple and preferred food in Botswana. However home processing of the grain, traditionally done by hand with mortar and pestle, is time consuming. Research to adapt and develop dehulling machinery was begun in 1975. As a result, there are now 21 small-scale mills based on built-in-Botswana dehullers in successful operation throughout the country. As these enterprises have matured, further adaptations have been made and various operating problems have come to light. This project will document these adaptations and problems, assess their implications for new installations and test several refinements to current mill design.

Post-Project Summary

This project surveyed 19 sorghum mills in Botswana and collected information on the physical layout; packaging methods; storage; methods of flour dust control; volumes of grain throughput; sorghum supply and distribution of flour; major management and technical problems; preventive maintenance; and successful repair services. The major problem reported by the mills was availability of sorghum at competitive prices for commercial milling. Technical problems were identified as pulley misalignment; worn belts; loose nuts and bolts; broken or loosely connected joints on extraction systems; improper sealing of slide valve mechanism; sorghum spillage; diesel spillage; air filters on diesel engine choked with dust; poor ventilation; and worn hammer-mill tips. The project reported that two mills changed, and two were in the process of changing, from diesel to electric power as advised by the Botswana Mill Owner's Association (BMOA) newsletter; a quick release mechanism was produced and tested on a limited scale; and, six sorghum dehullers were put into final testing with results indicating similar performances for the lined and unlined dehullers.

Recipient Institution(s)