yashchuk_tsepkalo (1)

screening device which allows smaller material to bypass the crusher itself, thus improving efficiency. Primary crushing reduces the large pieces to a size which can be handled by the downstream machinery.

Some crushers are mobile and can crush rocks (as large as 16 in), concrete and asphalt into material as it is driven over material on road surface, thus removing the method of hauling oversized material to a stationary crusher and back to road surface. They are used, for example in road constructions.

For the most part advances in crusher design have moved slowly. Jaw crushers have remained virtually unchanged for sixty years. More reliability and higher production have been added to basic cone crusher designs that have also remained largely unchanged. Increases in rotating speed, have provided the largest variation. For instance, a 48 inch cone crusher manufactured in 1960 may be able to produce 170 tons/h of crushed rock, whereas the same size cone manufactured today may produce 300 tons/h. These production improvements come from speed increases and better crushing chamber designs.

The largest advance in cone crusher reliability has been seen in the use of hydraulics to protect crushers from being damaged when uncrushable objects enter the crushing chamber. Foreign objects, such as steel, can cause extensive damage to a cone crusher, and additional costs in lost production. The advance of hydraulic relief systems has greatly reduced downtime and improved the life of these machines.

4.Answer the questions to the text:

1.What is a crusher?

2.Where are crushers primarily used?

3.What types of crushers do you know?

4.What is crushing?

5.What kind of crushers is most reliable in use?

6.What is the difference between the crushers and the mill?

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7. What is crusher classification based on?

5.Match the words to make up possible word combinations:

6.Try to put these words in the right order and make a sentence:

1.A crusher is / to reduce / smaller rocks / a machine designed / into / large rocks.

2.Crushers are / material / particle size / used / to reduce.

3.Foreign objects / a crusher / can cause / damage to /extensive /.

4.Each crusher is /with /raw material /a certain maximum size of / designed to work.

5.The raw material / delivered to /by dump trucks /usually / is / the primary crusher's hopper.

6.Each crusher / of raw material / to work / a certain maximum size / is designed / with /.

7.Crushers / which / are machines / to break or compress / materials / use a metal surface /.

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7. Say if the statement is true or false. If the statement is false give the

correct answer:

1)A crusher is a machine designed to reduce large rocks into smaller rocks.

2)For the most part advances in crusher design have moved rapidly.

3)Crushers are used to reduce particle size enough so that the material can be processed into finer particles in a grinder.

4)Crushing stages are followed by milling stages if the materials need to be further reduced.

5).Foreign objects can cause extensive damage to a crusher.

6)The raw material is usually delivered to the secondary crusher's hopper by dump trucks.

7)Jaw crushers have remained virtually unchanged for seventy years.

8.Read the following text. Retell it to a partner:

Hydraulic Cone Crusher

HP Series of highly efficient Hydraulic Cone Crusher is a world-level cone crusher introduced with the up-to-the-minute technology of Germany. The cone crusher not only improves the production capacity and crushing efficiency, but also widens applying area, hardness range of materials from limestone to basalt. It has a great crushing performance in the work of medium-size crushing, fine crushing and super fine crushing.

The crusher is the improved type of spring cone crusher and can be used to replace ordinary hydraulic cone crusher in the field of mining and construction. It is the most ideal equipment for large stone crushing factory and mining industry.

The performance of ordinary hydraulic cone crusher acts as the reference for the performance of HP series of cone crusher. As a composing unit of the

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production line, its performance can be influenced by other units like feeder, belt

conveyor, vibrating screen, motor, transmission part and hopper, etc.

9. Open the brackets choosing the correct form of the Participles.

Translate the sentences into Ukrainian:

l. A positively (charging, charged) particle having the mass.

2.The scientist found that X-rays (producing, produced) were complex.

3.Oppositely (charging, charged) particles exert forces of attraction on one another.

4.The work (doing, done) by these research-workers resulted in many new discoveries.

5.The investigation (following, followed) by many experiments was of great importance.

6.The nuclei (forming, formed) in this reaction are unstable.

7.When (working, worked) in the lab the students carried out many experiments.

8.The student (translating, translated) the article knows English very well.

9.When (heating, having heated) this substance one should be very careful.

10.(Investigated, having investigated, Investigating) all the properties of new water, they could understand, the mystery of silvery clouds.

11.The (dissolving, dissolved, having dissolved) materials may be soluble solids, liquids or gases.

12.Later (using, used, having used) in steam boilers, should be free from substances that cause corrosion.

10. Use the following sentences in all the forms and tenses adding suitable

adverbial modifiers where necessary:

1.People employ glass for many purposes.

2.Stainless steel is widely used in chemical machinery.

3.Pumps find many applications in the chemical process industries.

4.A crusher is a machine designed to reduce large rocks.

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11.Translate into Ukrainian paying attention to the word "for":

1.Our age is called the age of atom, for we use the atom for various purposes.

2.For a long time scientists were not able to discover the secret of the atom.

3.Hydrogen is widely used for it contains a large amount of chemical energy.

12.Pick up the key words from the text “Crushers”. Make up your own sentences with them.

13.Write an abstract to the text “Crushers”.

14.Get ready for presenting the topic “Crushers” at the conference ”Innovations in Science and Engineering” based on the following questions of Task 4.

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LESSON 9

1.Read and memorize the following words:

2.Read and memorize the following word combinations: particle size reduction зменшення розміру частинки

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3.Read and translate the text into Ukrainian.

Grinders

A grinding mill is a unit operation designed to break a solid material into smaller pieces. In materials processing a grinder is a machine for producing fine particle size reduction through attrition and compressive forces at the grain size level. A grinding mill crushes material between two closely placed, heavy objects like stones. They are rotating with respect to one another so the material gets crushed like in a mortar and pestle. The rotating motion of the partially filled industrial grinder can make cascading effect that decreases the material to a very fine and give it powder shape or convert it in to powder form. There are many different types of grinding mills and many types of materials processed in them.

The grinding of solid matters occurs under exposure of mechanical forces that trench the structure by overcoming of the interior bonding forces. After the grinding the state of the solid is changed: the grain size, the grain size disposition and the grain shape. Dry chemicals can be ground to a uniform particle size (to a specified fineness) which enables optimal dispersibility, reactivity, and processing uniformity.

Grinding may serve the following purposes in engineering: increase of the surface area of a solid, manufacturing of a solid with a desired grain size, pulping of resources.

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In industrial and manufacturing process there are different types of industrial grinders used for breaking down and mixing rough material like paints, chemicals and ores. Industrial grinder can cut, shape and reshape metal and it can grind any thing into small pieces or some can present in a powder form.

Grinding machines are mainly applied for the powder processing of mineral products in the industries of metallurgy, construction materials, chemicals, mining, etc. A grinding machine can produce powder from various non-flammable and non-explosive mineral materials, such as quartz, feldspar, talcum, barite, cinder, cement clinker, activated carbon, dolomite, granite, soft coal, coking coal, lignite, gold ore, red clay, clay, coke, coal gangue, porcelain clay, bentonite, pyrophyllite, shale, red stone, basalt, gypsum, graphite, carborundum, heat insulating material, etc.

One of the most commonly used industrial grinders is called a ball mill. It rotates on a horizontal axis and has a cylindrical design. A slightly inclined or horizontal rotating cylinder is partially filled with balls, usually stone or metal, which grinds material to the necessary fineness by friction and impact with the tumbling balls. Ball mills are characterized by comparatively smaller diameter and longer length. The feed is at one end of the cylinder and the discharge is at the other. Ball mills are commonly used in the manufacture of Portland cement. These industrial ball mills are mainly big machines. Small versions of ball mills can be found in laboratories where they are used for grinding sample material for quality assurance.

Different type of materials can be used as grinding media in an industrial grinder, such as flint pebbles, stainless steel balls and ceramic. Sometimes the final stage of crushing and the preliminary stage of grinding are economically combined into one operation.

Impact crushers can be used to combine crushing and grinding, in one operation. Impact crushers involve the use of impact rather than pressure to

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crush material. These machines offer the lowest capital cost of any grinding mill. Hammer speeds of 4,000 ft/min. will suffice for a course product, but upwards of 15,000 ft/min, may be required for fine grinding. With different forms of crushing chambers, grinding elements and discharge screens, they can be built to handle and reduce almost any material that is not too abrasive: as coal, seeds, limestone, gypsum or soft metallic ores. Impact crushers can be adapted for wet crushing and grinding to produce a slurry, in this way serving an additional purpose, but there is some loss of machine capacity and an increase in power consumption when the machine is used in wet operations. They are used for grinding and classifying non-metallic minerals and dry chemicals to a fineness ranging from 800 to 35 microns with a high degree of uniformity.

4.Answer the questions to the text:

1)What is a grinding mill designed for?

2)How does a grinding mill work?

3)What purposes in engineering may grinding serve?

4)What mineral materials are used for producing powder by a grinding machine?

5)What is the most commonly used industrial grinder

6)How does a ball mill operate?

7)What machines are used to combine crushing and grinding in one operation?

8)What materials are impact crushers designed to handle and reduce?

5. Say if the following statements are true or false. If the statement is false

and explain why:

1)A grinding mill crushes material between two closely placed, heavy objects like stones.

2)Dry chemicals can be ground to a dissimilar particle size.

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3)A grinding machine can produce powder from various flammable and non-explosive mineral materials.

4)Cinder isn’t used for producing powder by grinding.

5)A ball mill grinds material to the necessary fineness by friction and impact with the tumbling balls.

6)Flint pebbles, stainless steel balls and ceramic can’t be used as grinding media in an industrial grinder.

7)The preliminary stage of crushing and the final stage of grinding are economically combined into one operation.

8)Impact crushers involve the use of impact rather than pressure to crush material.

6.Сhoose the correct item to complete the following statements:

1.In materials processing a grinder is a machine for producing fine particle size reduction through ______

a) compression b) attrition

c) friction

2.In industrial and manufacturing process there are different types of industrial grinders used for breaking down and mixing rough material like_____

a) paints b) gravel c) rocks

3.Ball mill rotates on a horizontal axis and has a cylindrical______

a)design

b)casing

c)form

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