Equipment Procurement, Installation and Use

Flour fortification involves adding standard quantities of nutrients (usually in the form of a premix) to a set quantity of flour, and mixing them together to ensure a uniform product.

Three approaches have been used to mix nutrients with flour.

• continuous mixing is commonly used in medium to large scale milling operations.
• batch processing, in which a set quantity of flour and a predetermined quantity of premix are placed in a container and mixed, is used in smaller operations.
• two-stage mixing, which involves preparing a preblend, which is then mixed with a larger quantity of flour, was used in the former Soviet Union, but is no longer common practice.

Fortification in continuous systems requires that the dry premix powder be added to the flour stream at a steady dosage rate, determined by the rate of flour flow. This requires:

• a feeder or 'dossifier' to meter out the required premix and keep it flowing freely, with a mechanism to adjust the rate of flow of the premix.
• a means to deliver the premix into the flour and
• some level of mixing after the premix was added to the flour.

Feeders commonly control the rate of premix addition by measuring the volume of material being added. Other ways are to measure the weight, or the loss of weight. The latter systems are more expensive and more complex to use.

There are different types of feeders, which range in design from simple to complex and in price from about US$ 1,000 to US$ 25,000. An important consideration is that the feeder needs to be easy to clean, maintain and repair. Screw type feeders are commonly used in new installations. Other types include the older revolving disk type, and the drum type, commonly used to add flour treatments, and still found in mills all over the world. The choice of number, type and size of feeder is determined by mill capacity.

Selection and procurement of feeders and mixers

Click here for detailed information about the selection, and procurement of feeders.

The manual also includes a list of manufacturers and suppliers from Europe, North America and from developing countries who meet a set of criteria related to the use of feeders for fortification programs in developing countries. Contact details are provided Selection criteria and recommendations based on technical suitability are also included.

The manual provides an assessment of the costs and funding options that can be considered under different circumstances and in different countries/regions. Also see MOST Companies Manufacturing Batch Mixers, Blenders, Feeders for additional companies supplying equipment

Setting up and calibrating a feeder:

Click here for a step-by-step guide on setting up and calibrating a feeder, and dealing with set-up and operational problems.