Part 2. Modern milling machinery.

Exercise 1. Read and translate the following words without a dictionary.

Specialist, spiral conveyor, magnetic, metal, aerodynamic, section, product, fundamental.

Reading. Read the text, study the scheme (Figure 40) and fill in the brackets with the correct number.

Modern flour processing consists of a complicated series of rolls, sieves, and purifiers. Approximately 72 percent of the grain finally enters the flour sack.

A modern milling plant (Figure 40) may comprise the following units:

· Receiving bin for grain (1) - a bin with a sieve for gross non-grain impurities

· Grain cleaning separator () for separation of impurities differing from grain in width, thickness and specific gravity

· Emery scourer () for the grain debranning and degermination

· Aspiration channels for separation of impurities differing from the grain in aerodynamic properties

· Magnetic trays () for separation of magnetic metal contaminants

· Damping system () and resting bins () for humidifying grain with warm water so that the grain acquires the necessary technologic properties before milling

· Horizontal scourer () for fine cleaning of the grain after resting

· Milling section with roller units - break roller unit () and grinding unit (). Each unit is provided with individual drive. Grain and intermediate process products are processed on the break, grinding, scratch and enrichment systems.

· Sifting section with plan-sifters () for sifting and grading of the process products

· Mechanical conveying means - spiral conveyors () - to transport the grain in the preprocessing section and to feed the grain to the milling section

· Pneumatic conveying means - centrifugal blowers, cyclone-dischargers, rotary locks, product pipelines () and air ducts (14) - for carrying the product in the grinding unit and feeding the flour and bran to the sacking bins ()

· Filter sleeves () with bins to decrease dust content in the air · Finisher for separation of endosperm and break tails

· Middlings purifier for enrichment of semolina and macaroni semolina · Production process control unit ()

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The sacked flour may consist of 20 or more streams of flour of various states of purity and freedom from branny specks. By selection of the various flour streams it is possible to make flour of various grades. Improvements in milling techniques, use of newer types of grinding machinery in the milling system, speeding up of rolls, and improved skills have all resulted in flour produced by employing the fundamentals of the gradual reduction process but with simplified and shorter milling systems. Much less roll surface is now required than was needed as recently as the 1940s.

Some specialists state that flour ground on stone grinding mills has certain advantages compared to flour produced on roller mills. This is due to the fact that the stone grinding mills cut and tear the material while the fine-grooved or smooth rollers of the last step of the roller mill plants only press the material.

Exercise 2. Answer the following questions.

1. Why do mills have flour output about 70 percent?

2. Why are stone grinding mills used in flour milling more widely than roller mills? 3. What are the functions of scourers?

4. What scourers are used in wheat milling?

5. What machines are applied to sieve the flour?

6. What types of conveying means may be included in the milling equipment?

7. What machines are used for separation of different impurities from the cereals? 8. What principles are in the basis of their operation?

9. Why is it sometimes necessary to use damping system? 10. By what way may the process control be done?

Exercise 3. Match the machines with their purposes.

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