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Grinding is one of the most power- and time-consuming daily tasks of women in rural Africa. Often the women give highest priority to the mechanization this work. It could give them time for other economic and social activities, thus being a precondition for other projects designed to improve the situation of women in rural areas.
The animal-powered mills installed so far are mostly operated by rural women's cooperatives. The concrete and difficult task of organising the operation of the mill often leads to a clear consolidation and strengthening of such self-help organisations.
The animal-powered mill utilizes the work of draft animals, i.e. a renewable source of energy, which is available in many developing countries. It contributes to the preservation of the environment, the saving of fossil fuels and thus also to the saving of foreign currencies.
The local artisans play a central role in their propagation. In order to enable a commercial dissemination of the device in the internal economic circulation in the long run, the power gear is so designed that it can be manufactured by metal craftsmen with comparatively simple . workshop equipment. The local craftsmen are also responsible for repairs and for training the maintenance staff. This means that a successful implementation of animal- powered mills must always be combined with a punctual promotion of artisans by means of training activities, acquisition of tools and loans etc.
2.1 Nutritional habits and working rhythm
So far, the project has gained experience mainly in the field of animal-powered mills used for millet grinding. First tests were performed for maize milling, as well as for driving rice hullers and manioc mills, by means of power gears.
In those regions where millet is the basic food, fermented millet flour is often preferred. After removal of the indigestible husks, the millet is soaked in water overnight for fermentation, so that its taste becomes slightly sour. In times of overwork, e.g. during the harvest, however, fermentation, and in some regions even the removal of husks, is dispensed with.
Two different traditional milling procedures are used in West Africa:
- pounding of millet in a mortar
- grinding of millet between two grinding stones
The two procedures are based on different working rhythms. In those regions, in which the cereals are ground with grinding stones, the grains are dried before grinding, whereas in the mortar the millet is pounded while it is humid.
If the grains ground by the animal-powered mills are too humid, the mill becomes sticky, so that no acceptable flour can be produced. Therefore, in those regions where the mortar is traditionally used, the grains must be dried in the morning after the overnight fermentation, before they can be ground in the afternoon, or soaking of the millet must be dispensed with, which would, however, cause a difference in taste.
Tab. 1: The traditional working rhythm of flour production, shown by the examples of Senegal and Burkina Faso, and the change required by the introduction of animal-powered mills.
|
|
Grinding stones fermented flour |
unfermented flour |
Wooden mortar fermented flour |
Animal powered mill fermented flour |
unfermented flour |
|
Afternoon |
glume removal |
___ |
glume removal |
___ |
___ |
|
Evening |
grain washing preparation of fermentation |
|
grain washing preparation of fermentation |
glume removal |
glume removal |
|
Night |
fermentation |
___ |
fermentation |
fermentation |
|
|
Morning | |
|
glume removal |
grinding | |
|
Noon |
drying |
drying |
further fermentation or drying |
drying |
short drying grinding |
|
Afternoon |
grinding | |
|
grinding | |
|
Evening |
food preparation |
|
food preparation |
food preparation | |
Table 1 shows traditional working rhythms and their alterations required by the introduction of animal-powered mills. Work with animal-powered mills requires coordination among the women, which was not necessary when grinding stones or mortars were used individually. If the millet is dried before grindings the flour can be stored for a few days, which is a positive secondary consequence. This feature can facilitate the organisation of the mill use if the women can be convinced to grind millet on stock.
The consumers test the quality of the flour optically, haptically (i.e. by touching) and in terms of taste. The following parameters influence the quality:
- the fineness (average size distribution of the individual particles)
- the homogeneity (uniformity of size distribution)
- the hardness (depends on the grain size and humidity content)
- the colour (depends on the humidity and on whether extracts or the whole grain were used).
Tab. 2: Characteristic curve of the flour produced by traditional processes.
| |
Grinding with grinding stones |
Grinding with mortar |
|
Fineness |
relatively fine |
relatively coarse |
|
Homogeneity |
relatively homogenous |
relatively inhomogeneous |
|
Humidity |
dry |
humid |
|
Hardness |
hard |
soft |
|
Colour |
bright |
bright |
Table 2 shows the flour qualities achieved using the traditional processes. The fineness is probably the most important criterion for the evaluation of the flour. This is not only due to its taste, but fine flour also signals wealth, because the fineness of the flour produced by traditional processes indicates how much working time the family can spend on grinding. The flour ground with the help of the power gear is furthermore compared with the product of the motor mill, so that fine flour is also regarded as an indication of progress.
Still, often the consumers disapprove of flour which is fine, but inhomogeneous, because it is not fine enough. This can be remedied by sieving out the coarse particles after the first grinding process. If fine, humid flour is compared with equally fine, but dry flour by "touching", the humid flour appears to be finer ("woollen granularity"). The use of cereals with too high a humidity content can lead to differences in colour and taste. Furthermore, insufficient cleaning of the mill influences the colour and taste, because spoilt particles mix with the flour.
Investigation and counseling steps
examination of the traditional organisation of work
evaluation of the quality of the flour produced by traditional procedures regarding
- fineness
- homogeneity
- humidity
- hardness
-colour
determination of the necessary processing capacity and of the processing peaks which must be covered by the capacity of the mill.
trials with the animal
-powered mill:
- adjustment of the millstones
- drying oftrains
- sieving of flour
food test with consumers until a satisfactory flour quality is achieved
counseling of the women regarding the organisation of work and coordination among themselves, advantages of stockkeeping
technical counseling of the women with respect to mill adjustment, drying, sieving procedure, cleaning of the mill.
2.2 Possible problems for the use of draft animals and power gears by women
Often the women's fear of handling the draft animals and mainly the resistance of the men, who mostly have the disposing power of the draft animals, still prevent the women from working with draft animals.
Traditionally, the preparation of food is a female duty; and the men are responsible for handling the technical equipment. In West Africa, the social position of women is determined above all by the quality of their housework. With respect to housekeeping, the men totally depend on the women. Therefore, the social position of the women would certainly be weakened if a considerable part of the housework, namely grinding, was taken over by the men. For this reason' in the case of most power gears installed so far the women were familiarized with handling the draft animals and the animal-powered mill. The women organise the operation of the mill, operate the device and harness and unharness the draft animals themselves. But they often leave those works- they consider to be technical jobs, such as cleaning the mill, to the men.
The experience made so far shows that women are certainly willing to work with draft animals, if this is clearly advantageous for them. In this case they mostly have energy enough to convince their husbands to make concessions. It proved to be advantageous that, if the men still refuse their consent, the women's group buys one or two draft animals designed exclusively to drive the power gear.
Usually it is more readily accepted socially if the women work
with donkeys than with, e.g., oxen.
Investigation and counseling steps
examination, in how far resistance on the part of the men and women against the use of draft animals by women is to be expected
training of women for handling draft animals
2.3 Questions concerning animal keeping
So far, donkeys, oxen and horses have been used as draft animals for animal powered mills. The employment of donkeys as draft and pack animals is very widespread, they are also frequently used by women. They are easy to handle, relatively insensitive, live on very little and are much cheaper than other draft animals.
Oxen are more expensive, more difficult to train and make more demands regarding feeding and care, but are more powerful than donkeys.
As far as horses are concerned, the situation varies very much, depending on the country and the region. In Burkina Faso, e.g., horses are very expensive. They are mostly owned by rich people, for whom the horse is more of a status symbol than of a work animal. In Senegal, however, horses are frequently used as draft animals.
The regular employment of draft animals for animal-powered mills makes higher demands regarding their care and feeding than their temporary use for soil treatment and transportation. This means that care for the draft animals must be improved by targeted training and counseling activities. First of all it must be ascertained whether the economic basis for sufficient feeding of the draft animals is secured during the dry season, too.
Investigation and counseling steps
register available draft animals find out disposing powers
examine feeding situation
select draft animals with respect to the factors
- disposability
- disposing power
- costs
- care capacity
- basis of feeding
training of the future mill users in handling the draft animals
counseling with regard to feeding of and care for the animals, training of care staff
2.4 Manufacture of animal powered mills by craftsmen
Animal-powered mills can be manufactured by local craftsmen with relatively simple workshop equipment. In addition to the usual tools, such as hammers, spanners, pliers, and manual saws, a welding unit and a drilling machine are needed. A forging equipment is desirable, but it is not a necessary precondition for building animal-powered mills.
Since animal-powered mills can be produced locally and are competitive with motor mills, a strategy can be chosen which aims at an automatic commercial dissemination of the device in the medium term. Therefore, local private craftsmen must be integrated into the production of and the post-support for the installed power gears as early as possible.
The craftsmen should:
- be open to innovations and improvisation
- have a certain spatial faculty of imagination
- be able to work with a high degree of exactitude
- possibly have knowledge in forging.
Investigation and counceling steps
selection of an adequate workshop
training of the craftsman "on the job"
3.1 Functional principle of animal-powered mills
The driving gear of the animal-powered mill is so designed that it can be produced by craftsmen in developing countries. The grinding unit used so far is an industrially manufactured cereal mill produced by the company Moulis and imported from France. It is a disk mill with stone disks, which was originally designed for manual and motor operation. In principle, all disk mills with a disk diameter of 18-20 cm can be used in connection with a power gear. However, comparative examinations of small commercial mills showed that the Moulis mill is the best, although it also has numerous constructional deficiencies. The selection of the grinding unit should be determined not only by the size of the millstones, but also by a solid construction, good bearings and easy cleaning, which are necessary because of the great torques exerted at the power gear. A grinding unit which can also be manufactured by local craftsmen is still under development.
The grinding unit has a horizontal axle. This means that the power gear must meet two requirements:
- it must convert the movement of the draft animals around a vertical axis into the rotation of a horizontal axis;
- it must gear up the slow circular movement of the animals (2-3 rounds/minute at a circle diameter of 8 m) to 40-100 times this speed.
Fig. 5: In the animal-powered mill,
power deviation and transmission are achieved via a wheel which runs on a wall.
The power gear designs known from the traditional usage areas and from Europe mostly achieve this goal by means of a multistage toothed gearing. This interlocking type of power transmission had the consequence that the power gears had to be over dimensioned in order ta resist overloads, e.g. when the working machine blocked.
In the animal-powered mill, power deviation and the first transmission are achieved by means of a wheel which runs on a circular wall. This wheel is connected to a centralized axle via a frame and is pulled by the animal running round in a circle. A chain drive links the wheel and the grinding unit, which is fixed to the frame, thus forming the second transmission stage (Fig. 5).
This system offers two advantages:
- A high transmission is achieved by two gear steps (up to 1/140).
- Contrary to toothed-wheel power gears only series components are used, which are available in many developing countries.
- The friction principle limits the tractive power exerted by the draft animal, so that over dimensioning of components can be dispensed with (important e.g. in case the cereal mill blocks).
- By using series components and since over dimensioning can be dispensed with, the material costs are low compared to the traditional toothed-wheel power gears.
3.2 Grinding output
The grinding output of animal-powered mills varies very much, depending on the desired flour quality and the capability of the draft animals. Table 3 shows the grinding output determined for the animal-powered mills installed so far.
If very fine flour is desired, and if only badly fed and weak draft animals are available, the lower values indicated in the table are more likely to be achieved, whereas the higher values can be assumed in the case of stronger draft animals and more coarse flour.
3.3 Evaluation of output and flour quality
Especially in the initial phase of the introduction of animal-powered mills it is necessary to systematically monitor the quality of the flour ground with the help of this mill type and the per hour output of the mill. Any deficiencies of the mill can usually be evaluated only if these parameters are compared to those of other animal-powered mills, which have already been tested, on the basis of possibly objective standards.
The users normally express their criticism of the mill and the
flour quality in a relatively general way. It is the duty of the supporting team
to find out the precise reason for any possible discontent.
For example, if
the output is too low? this can be due to constructional faults, but also to a
bad organisation of work, too weak animals or wrong adjustment of the mill.
The output can be judged only if the flour quality is determined at the same time. If fine flour is ground the output is usually lower than in the case of coarse flour.
The decisive criterion for the evaluation of the flour quality is the fineness of the flour. It is described by a particle-size distribution curve and the fineness index. With the help of the fineness index it is possible to compare the flour ground by the animal-powered mill with the traditional product and the flour produced by a motor mill (Annex 1, p. 61).
Tab. 3: Output of the animal-powered mills installed so far. (The figures are based on the determination of the grinding time needed for quantities of 2 kg.)
|
Country |
traditional process |
grinding stock |
intended use |
draft animal |
grinding output |
remarks |
|
Burkina Faso |
grinding stones (relatively fine flour) |
millet |
food flour |
donkey |
5-15 kg/h |
animals are in bad health and food conditions |
|
Burkina Faso |
grinding stones (relatively fine flour) |
millet |
Dolo (only coarse grinding required) |
donkey |
30-50 kg/h | |
|
Senegal |
mortar (relatively coarse flour) |
millet |
food flour |
donkey |
10-12 kg/h | |
|
Senegal |
mortar (relatively coarse flour) |
millet |
food flour |
horse |
15-20 kg/h | |
|
Senegal |
mortar (relatively coarse flour) |
maize |
food flour |
donkey |
8 kg/h | |
|
Sierra |
mortar |
maize |
food flour |
ox |
14 kg/h | |
|
Leone |
(relatively coarse flour) | | | | | |
|
Sierra |
mortar |
maize |
food flour |
pair of oxen |
20 kg/h | |
|
Leone |
(relatively coarse flour) | | | | | |
|
Central African Republic |
mortar (relatively coarse flour) |
millet |
food flour |
ox |
15 kg/h | |
| |
mortar(relatively coarse flour) |
manioc |
manioc flour |
ox |
34-38 kg/h |
with modified grinding unit of the company Irus (modified hopper and feeding screw) |
Investigation and counseling steps
performance of test meals or distribution of flour samples to families. Interviews with the consumers. Systematization of the criticism.
determination of the output of the animal-powered mill, comparison with other power gears that have already been tested
determination of the particle-size distribution curve and of the fineness index, comparison with the particle size distribution curve and the fineness index of the traditional product
evaluation of the test results, identification of deficiencies and problems in the field of technology and organisation of work. If necessary, technical and organisatorial alterations.
Investigations conducted in West Africa have shown, that even small motor mills with a capacity of 80 kg/in can work economically only in the case of a user circle of 1000 to 1500 consumers. Therefore, motor mills which work on a commercial basis are mostly found in towns or bigger villages.
The animal-powered mill is designed for a consumer circle of approximately 100 persons with a daily operation time of four hours, or 200 persons with a daily operation time of eight hours. This results in 10 to 25 actual female users - a number which can be justified also with respect to organisatorial considerations, if a family size of 8-10 persons is assumed.
Although the employment ranges of animal-powered mills and motor mills differ substantially, as shown in Annex 3 (p. 65) and Fig. 7 (p. 19), animal-powered mills are often compared to motor mills.
In fact, motor mills have the advantage over animal-powered mills, that they apparently "automatically" produce flour of almost any fineness. Animal-powered mills, on their part, have a relatively low grinding capacity, require a certain degree of coordination among the users, require a draft animal, which must be harnessed and unharnessed, and produce a more inhomogeneous flour. Although the flour quality certainly corresponds to that achieved by traditional methods, and although the time consumption, including the travelling and waiting times, necessary for the use of the animal-powered mill is not higher than in the case of the motor mill, the motor mill is often regarded as the "more progressive" solution.
This is a problem particularly in those regions, where the motor mill is known by mere report, but not by own experience. When the population has already gathered experience in terms of maintenance problems and costs caused by a motor mill, it is much easier to explain the advantages of the animal-powered mill.
Fig. 7. Particularly in small
villages, animal-powered mills are a real alternative to motor mills. The
milling costs of animal-powered mills drop below DM 0.05/kg when approximately
20 to 30 families use it, whereas this price is obtained only when about 150
families use a motor mill. (1 DM <= 0,54 $ US)
When selecting the locations for animal powered mills, care must be taken that the number of persons to be equipped with this milling facility does not become too big, because this may lead to disputes about the right to use the mill. If necessary, several mills must be installed in one village.
The women should pay an adequate price for the use of the mill, which allows them to finance the maintenance and repair works themselves, and to replace the mill after expiry of the estimated useful life. It would probably be best if the women paid this grinding price in the form of a monthly contribution to a common fund, other types of organisation are also conceivable.
Annex 3 (p. 65) lists comparative figures for the determination of the necessary grinding price.
Investigation and counseling steps
examine prior experience with motor mills
establish a public image on the question "motor or animal-powered mill", with particular regard to influential persons (chiefs, missionaries, etc.)
examine and point out the economy and easy maintenance of the animal powered mill in comparison with the motor mill in the respective context
examine and compare the time consumption required for the use of animal-powered and motor mills
determine the potential user circle
determine the required grinding price
give organisatorial counseling with respect to the payment of the grinding price
In most existing locations, the animal-powered mills are owned collectively by women's groups. In Senegal, the groups elected two women, who are responsible for monitoring the operation, and a mechanic for servicing the device. In Burkina Faso, control mostly lies with "mill committees", with equal representation of men and women.
The grinding price is usually paid in the form of a weekly or monthly contribution to a common fund. As a rule, all members of the women's group, or all women who have shared the costs of the installation, have access to the mill.
In most cases every woman uses her own donkey, or that of her family, as draft animal. If the men do not accept this, or if other organisatorial problems occur, the women's group can also purchase several draft' animals (at least two), which are exclusively used to drive the power gear. In this case a person must be appointed who is responsible for the care for the animals.
The women's group should not be big, and its members should possibly live in the same neighbourhood in order to facilitate the coordination of the mill use.
Other types of organisation are conceivable as an alternative. For example, the women could hire a miller, who would be responsible for all questions concerning the mill operation, maintenance and care for the animals. This model has the advantage of clear responsibilities and optimum mill operation, which would certainly have effects on the flour quality and the grinding output. On the other hand, the grinding price would increase' knowledge would be monopolized, and the women would become dependent on the miller.
Another conceivable model would be the commercial operation of the mill by a private miller. In this case it is doubtful, however, whether an animal-powered mill could satisfy the profit expectations of a private entrepreneur. Such a model would also have the above-mentioned advantages, but would totally cut off the women from flour production.
Because of profitability reasons, the last two models can be realized, if at all, only if oxen are used as draft animals, since the miller's income can be achieved only by a higher flour output.
Investigation and counseling steps
examine in how far women's groups already exist, which organisation structures they have
judge the dynamics and readiness for innovations
find out the responsibilities within the group - overall responsibility - organisation of the fund
- maintenance of the power gear - if necessary, care for the draft animal
determine the organisation of the mill use - which draft animals are used - who may grind when
The network of problems in the different fields, which are
inherent in the first implementation of animal-powered mills requires an
implementation strategy which allows to disentangle the problems.
It has
turned out to be useful if first a trial and demonstration programme is
performed in a technological centre, a demonstration farm or similar. The centre
should be situated in a place where demonstrations for interested farmers and
peasant women can be held. Local projects and organisations, which are likely to
be the future executing organisations of the project, should be integrated at an
early stage into the trial and demonstration programme.
These organisations may include rural development projects, women's projects, projects working in the field of animal power or projects active in the branch of food processing.
The trial and demonstration programme has four objectives:
- to create interest for the use of animal powered mills among the rural population,
- to adapt the milling power gear to local requirements (in particular to the flour quality desired in the respective region),
- to evaluate the chances of the power gear to be accepted in the village,
- to judge the local executing organisations.
Good experience was made with the installation of a first demonstration mill on the premises of particularly innovative private individuals, e.g. the family of the craftsman together with whom the power gear was built.
The demonstration programme should particularly be aimed at the
inhabitants of those villages, in which the animal-powered mill can probably be
installed in a further step.
The following criteria should be applied when
selecting the villages in which such a pilot project could be installed:
- adequate size of the village;
- there are no functioning motor mills, or they are not used by the population;
- population is ready for innovations;
- functioning women's groups;
- readiness to participate in the installation of the mill financially and by means of work.
The financial participation of the village population should be proportionate to the relatively high risk they run by testing a widely unknown technology. In Senegal and Burkina Faso, the villages normally contribute 10-20 % of the installation costs. In many cases the foundations and the circular wall are built by the villages by self-construction.
Within the framework of a pilot programme, animal-powered mills may be installed in villages only when it is foreseeable that the flour is accepted by the population, and that the users are able to organise the operation of the animal-powered mill.
During the pilot programme the villages need intensive support of a counseling team.
The team should include at least a technician, a craftsman and a female village counselor. The latter two should be local staff.
In particular the counselor must be familiar with the culture and the way of living of the women in the villages (especially their cooking and food habits) and understand their language - in the double sense of the word.
She will have the following training and counseling duties
- to train the women for handling the draft animals
- counseling with respect to possibly necessary changes in the working rhythm and the organisation of the mill use
- counseling regarding the food preparation, taste tests, cooking tests, experiments with different fermentation times and flour finenesses
- technical training: handling and maintenance of the machine
The craftsman will also be responsible for technical counseling,
if this is not realised by the counselor, and for training the maintenance
staff, insofar as men are concerned.
The technician should solve difficult
technical problems.
Investigation and counseling steps
identification of a suitable location for a trial and demonstration programme
identification of potential executing agencies
performance of demonstrations for village inhabitants
selection of suitable villages for a pilot programme
selection and training of counseling staff
working and organisation scheme for the counseling activities
- responsibilities
- investigations to be performed
- time schedule
- reporting
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