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Ores

A crude is any mixture of minerals in the form in which it occurs as a part of the earth’s crust. An ore is a solid crude containing a valuable constituent in such amounts as to constitute a promise of possible profit in extraction, treatment and sale.

The valuable constituent of an ore is ordinary called valuable mineral or often just mineral: the associate worthless material is called gangue. In some ores the mineral is the chemical state in which it is desired by primary consumer, e. g. graphite, sulphur, asbestos, talc, garnet; in fact this is true of the majority of non-metallic minerals. In metallic ores, however, the valuable mineral is rarely the product desired by the consumer, and chemical treatment of such minerals is a necessary step in the process of beneficiation. In such cases the sale product is usually the result of concentration by the method of ore-dressing followed by further concentration by the chemical methods of metallurgy. The valuable product of ore-dressing is called concentrate, the discarded waste material is tailing.

Concentrate is, in most cases, the feed to the metallurgical plant. If the metallurgical processes is one in which separation is effected in melt, the process is called smelting; if the separation is effected by differential or selective solution, the process is leaching or lixiviation.

Metals occur in ores either in the native state (e.g. Au, Ag, Pt, Cu) or as salts or oxides (CuS, Fe2O3, PbCO3), etc. But no matter what chemical form, the metal or mineral is invariably associated with more or less - usually more - barren rock. The form, in which the metal is required by the primary customers, is a relatively pure substance. Hence a more or less extended process of purification, usually involving, in order, ore-dressing, metallurgical extraction, and chemical refining, intervenes between delivery of ore at the mine exit and delivery of the metal to the customer.

One way in which the nonferrous metals differ from iron is the manner of its occurrence. Iron oxides occur in large and comparatively pure deposits; the other metals and compounds from which metals are delivered are scattered through large volumes of rock, such as limestone or quartz. Since it would be difficult and costly to smelt these large amounts of barren rock, metallurgists have recourse to concentration or ore-dressing by which the metals or metallic compounds are partially separated from the gangue or worthless material, before smelting.

Flotation

Flotation is a method of concentrating solid minerals in a relatively finely divided state. It is essentially a method of gravity concentration in water in which the effective specific gravity of certain of the ore minerals is substantially decreased by causing air bubbles to attach more or less tenaciously to particles of that particular mineral, whereupon they float on the separating medium while unaffected minerals sink. When the selected mineral is separated in the form of a froth the operation is called froth flotation.



Steps of Froth-Flotation Method

In essential outline the ordinary simple froth-flotation operation comprises the following steps: 1) Grinding the ore in water to a maximum size of 35 or 48-m. 2) Dilution to a pulp consistency of 15 to 35 per cent solids; 3) Addition to the pulp a small quantities of one or more various inorganic conditioning agents, which have a number of functions; 4) Addition of a collector reagent which has the function of coating the mineral to be floated with a water-repellent film; 5) Addition of frothing agent which imparts persistence to bubbles when they reach the surface; 6) Aeration either by agitation, or by air injection as through the porous bottom of the containing tank, or through pipes, during which the coated mineral particles become more or less firmly attached to gas bubbles; 7) Separation of mineral-bearing froth from a liquid pulp containing residual particles which did not take on collector coating.

Підберіть українські еквіваленти до англійських термінів.

1. crude 2. valuable constituent 3. a promise of possible profit 4. is ordinary called valuable mineral or often just mineral 5. gangue 6. sale product 7. concentration 8. ore-dressing 9. concentrate 10. tailing 11. selective solution 12. metallurgical extraction 13. non-ferrous metals 14. flotation 15. froth flotation 16. 35 or 48-m 17. pulp consistency 18. conditioning agent 19. collector reagent 20. frothing agent a) реаґент; b) 35 и 48 меш (меш = № сита); с) консистенція пульпи; d) комерційний продукт; е) власне збагачення; f) звичайно називається мінералом або корисним мінералом; g) флотація; h) пінна флотація; i) пуста порода; j) збиральний аґент; k) кольорові метали; l) хвости; m) селективне розчинення; n) концентрат; o) корисний складник; p) збільшення долі корисного складнику; q) сировина; r) потенційний прибуток; s) витоплювання; t) аґент вспінування.

2. Доберіть з тексту терміни-антоніми:

a) tailing

b) gangue

c) commercial product

 

3. Виберіть вірне значення для термінів:

«збагачення»

а) додавання цінного елементу до руди;

б) збільшення долі корисного складнику шляхом видалення пустої породи, піску, глини.

 

«пульпа»

а) м'яка сполучна тканина, пронизана нервовими закінченнями, лімфатичними й кровоносними судинами, що заповнює порожнину зуба;

б) суміш твердих частинок з рідиною (вода й ґрунт, вода й корисні копалини).

 

Складіть ряди термінів-синонімів на основі тексту, який ви прочитали.

(ряд з трьох синонімів): beneficiation

(ряд з двох синонімів): selective solution

(ряд з двох синонімів): leaching

(ряд з трьох синонімів): gangue

(ряд з двох синонімів): metallurgical extraction

Проаналізуйте відмінності ідентичних за значенням речень на англійській та українській мовах, зробивши графічний синтаксичний розбір, визначте типи цих речень.

If the metallurgical processes is one in which separation is effected in melt, the process is called smelting; if the separation is effected by differential or selective solution, the process is leaching or lixiviation.     Відокремлення пустої породи від цінної складової мінералу під час проведення металургійного процесу називається витопленням; відокрем-лення вищезгаданих складників мінералу шляхом створення умов для селективного розчинення – вилу-жнюванням.
Flotation is a method of concentrating solid minerals in a relatively finely divided state. Флотація є методом збагачення твердих мінералів за допомогою відокремлення дрібної фракції.

 

Напишіть повні назви елементів на англійській та українській мовах

Au, Ag, Pt, Cu,

 

Випишіть з тексту слова та вирази, які є характерними мовними засобами зв’язку речень у текстах наукового стилю англійської та рідної мови.

Наприклад: hence, ….

таким чином, …

9. Підберіть тексти на рідній мові про руди та ознайомтесь з ними, зробіть повний письмовий переклад тексту “Ores”.

 

10. Підберіть тексти на рідній мові про процеси збагачення руди та ознайомтесь з ними, зробіть повний письмовий переклад тексту “Flotation”.

Індивідуальне завдання до змістового модуля 3

Особливості перекладу головних членів речення

The blast furnace in which smelting is accomplished is a steel shell about 70-80 metres high, lined with fire bricks. The internal diameter varies in the furnace, being about 10 metres at the widest part. Near the bottom of the furnace, air is blown in through nozzles known as “tuyeres”, located at intervals around the furnace. Near the top of the furnace is a passage to carry away the gases produced in the furnace, to be used elsewhere because of their heating values.

A part of the gas from the top is used to preheat the air, which is blown into the furnace though the tuyeres. This is accomplished in three or four stoves which are actually chambers filled with fire bricks. The gases from the top of the furnace are mixed air and coke-oven gases, and pass through the stoves and by combustion, heat up the brick work. When the desired temperature is obtained in the stove, the flow of gas is diverted to another stove in the opposite direction, and into the bottom of the furnace. When the bricks cool, the air is diverted to a hot stove, and the gas again admitted to reheat the bricks.

The blast furnace in operation may be considered as a high column of iron oxide and gangue, coke and limestone, all mixed together but being in individual lumps large enough to allow free passage of the air up through the interstices between the lumps.

Near the bottom of the column where the hot air is blown in there is a high temperature, and the carbon of coke unites with the oxygen of the air to form carbon monoxide, which passes up through the column along with nitrogen from the air:

C+O2→CO

As the carbon monoxide becomes cooler it can unite with more oxygen to form carbon dioxide. To do this, the monoxide takes up the oxygen from the iron oxide, in a comparatively pure state:

Fe2O3+CO→ Fe+CO2

As the material in the bottom of the column is consumed, the charge settles and finally reaches the hot part of the furnace, where the iron is melted and runs down to collect in the bottom of the furnace.

The molten iron is removed intermittently through a hole in the wall of the furnace.The hot gases going up the column heat the limestone and cause it to dissociate into calcium oxide and carbon dioxide:

CaCO3→CaO+CO2

The carbon dioxide escapes with the nitrogen at the top of the furnace, while the hot calcium oxide unites with the gangue to form a liquid slag which flows to the bottom of the column and remains on the top of the liquid iron. As the amount of liquid material in the furnace increases, the slag is draw off through a hole in the wall of the furnace above the iron tap hole. The slag is usually run into large ladles and taken to a granulation basin where the ladles are empted.

The pig iron from the furnace is sometimes cast into mouldsand allowed to solidify so that it can be conveniently transported or stored until needed. More often the pig iron is taken in the liquid state to the refining furnaces for the manufacture of steel.

The starting up or blowing in of a blast furnace is a slow and expensive process, and so once the furnace is operating nothing id allowed to interfere with the regular operation until wear of the lining necessitates shutting down to reline the furnace.During a good run, a blast furnace will produce 10-12 million tons of pig iron before it becomes necessary to reline it.

Прочитайте речення та їх переклади. Які методики використано для перекладу підмета (за підручником В. І. Карабана. Переклад англійської наукової і технічної літератури. – Вінниця «Нова книга»: 2004 – стр.575)?

The first process in the reduction of an iron ore is smelting in a blast furnace. Доменне топлення є першою ступеню відновлення залізної руди.
The smelting operation does this and at the same time separates the gangue from the iron. Подібну операцію виконує доменне топлення, яке водночас відділяє пусту породу від заліза.
The blast furnace in which smelting is accomplished is a steel shell about 70-80 metres high, lined with fire bricks. Доменна піч, в якій відбувається процес витоплення, є конструкцією, що складається із сталевого кожуха 70-80 метрів за ввишки, та його футерування вогнетривкою цеглою з внутрішньої сторони.
A part of the gas from the top is used to preheat the air, which is blown into the furnace though the tuyeres. This is accomplished in three or four stoves which are actually chambers filled with fire bricks. Частину колошникового газу використовують для підігріву повітря, яке призначене для вдування в піч через фурми. Підігрів повітря завершується в трьох або чотирьох повітронагрівниках, яки фактично є камерами футерованими вогнетривкою цеглою.
Near the bottom of the column where the hot air is blown in there is a high temperature, and the carbon of coke unites with the oxygen of the air to form carbon monoxide, which passes up through the column along with nitrogen from the air. У високотемпературному середовищі, яке формується біля ніжної частини колони шихти, в зоні, де вдувають гаряче повітря, карбон коксу поєднується з оксиґеном повітря і формується оксид карбону. Ця речовина разом з нітрогеном повітря підіймається вверх крізь стовп шихти.

Прочитайте речення та їх переклади. Які методики використано для перекладу присудка (за підручником В. І. Карабана. Переклад англійської наукової і технічної літератури. – Вінниця «Нова книга»: 2004 – стр.575)?

The blast furnace in operation may be considered as a high column of iron oxide and gangue, coke and limestone, all mixed together but being in individual lumps large enough to allow free passage of the air up through the interstices between the lumps. Доменну піч під час експлуатування, можливо, порівняти з високим стовпом, який складається з оксиду заліза та пустої породи, коксу, вапняку, які є перемішаними, але становлять собою куски матеріалу однієї речовини, що дозволяє повітрю вільно проходити вверх між кусковим матеріалом.
During a good run, a blast furnace will produce 10-12 million tons of pig iron before it becomes necessary to reline it. За умов задовільного ходу в доменній печі можливо призвести 10-12 міл. тон чавуну до того часу, як виникне необхідність футерувати її знову.
The product of the blast furnace is known as pig iron and is used for the manufacture of steel. Продукт доменного виробництва називають переробним чавуном и використовують для виробництва сталі.

 

Electric Arc Furnace

EAFs are used to produce special quality steels (steels alloyed with other metals) and some ordinary (non-alloy) quality steels – the lighter long products such as those used for reinforcing concrete.

Unlike the basic oxygen route, the EAF does not use hot metal. It is charged with "cold" material. This is normally steel scrap (recycled goods made from steel which have reached the end of their useful life). Other forms of raw materials are however available. They have been produced from iron ore. These include direct reduced iron (DRI) and iron carbide, as well as pig iron, which is iron from a blast furnace. It has been cast and allowed to go cold, instead of being charged straight into a basic oxygen vessel.

Steel scrap (or other ferrous material) is first charged into the EAF from an overhead crane. A lid is then swung into position over the furnace. This lid contains electrodes which are lowered into the furnace. An electric current passes through the electrodes to form an arc. The heat generated by this arc melts the scrap. The electricity needed for this process is enough to power a town with a population of 100,000 people.

During the melting process, other metals (ferro-alloys) are added to the steel to give it the required chemical composition. As with the basic oxygen process, oxygen is blown into the furnace to purify the steel, lime and fluorspar are added to combine with the impurities and form slag

After samples have been taken to check the chemical composition of the steel, the furnace is tilted to allow the slag, which is floating on the surface of the molten steel, to be poured off. The furnace is then tilted in the other direction and the molten steel poured (tapped) into a ladle, where it either undergoes secondary steelmaking or it transported to the caster.

The modern electric arc furnace typically makes 150 tonnes in each heat, which takes around 90 minutes.

A vast range of special quality steels is made in electric arc furnaces by adding other metals to form steel alloys. The most commonly-known of these is stainless steel, which has chromium and nickel added to form a corrosion-resistant steel.

Types of Steels

– What types of steels do you know?

– Excuse me, but your question sounds too general. According to their chemical composition, all steels are divided into carbon steels and alloy steels; according to their properties, into stainless steels, heat-resistant steel, high-resistant steels, and many others; and according to their use, into structural steels and tool steels. What exactly interests you?

– Chemical composition.

– You see, the quantity of carbon in steel decides the properties and uses to which the steel can be put. The important point to remember is that carbon will not be present as elemented carbon but combined with iron as cementite. The more cementite is present in steel, the more brittle and harder the steel becomes. Well, the plain carbon steels can be divided into the following groups: (1) dead mild steel (carbon up to 0.1%) used for hot and cold rolled strip, nails, etc., (2) mild steel (C 0.1 – 0.25%) used as structural steel, (3) medium carbon steel (C 0.25 – 0.6%) used for crankshafts, gears, rails, etc., (4) high carbon steel (C 0.6 – 0.85%) used for laminated springs, hammer heads, etc., and (5) tool steel (C 0.85 – 1.4%) used for springs, knives, drills, etc. Thus the user can choose between softness and ductility of a mild steel and the hardness and brittleness of a tool steel, with a medium carbon steel as a good compromise.

– And what about alloy steels? What alloying elements do they contain?

– Nickel, chromium, molybdenum, tungsten, vanadium, and manganese. There are some advantages which alloy steels possess compared with plain carbon steels. They are: (1) increased strength without loss of toughness, (2) increased hardness combined with toughness, (3) increased life under alternating stresses, (4) less reduction in strength at elevated temperatures, and others.

 

 

The important point to remember is that carbon will not be present as elemented carbon but combined with iron as cementite. They are: (1) increased strength without loss of toughness, (2) increased hardness combined with toughness, (3) increased life under alternating stresses, (4) less reduction in strength at elevated temperatures, and others.

Доповніть речення.

a) The rolls are made of ______ or _______.

b) The roll has two _____, on which the rolls revolves on bearings and a ________, on which the rolling is accoumplished.

c) For rolling plates, slabs and sheets, ___________ rolls are applied.

d) For rolling billets, bars and sections, ___________ rolls are used.

e) The roll grips the metal due to a force of ___________.

Перекладіть діалоги.

a) - What is rolling?

- Вальцювання – це обробка метала тиском. Валки є розташованими таким чином, що відстань між ними менша ніж товщина металу, який надходить до стану.

- What is a principle object of rolling?

- Головною задачею вальцювання є зламати грубу структуру металу.

- What is one the most important problems in rolling?

- Економія металу. Існує можливість досягнути економії металу шляхом використання полегшених профілів і профілів з високою точністю.

b) - How rolls are classified?

- The rolls may be plain or grooved. The larger rolls of the 4-high roll stand do not have a contact with metal and are called back-up rolls. The back-up rolls support the working rolls in operation and reduce their elastic deflection.

Ores

A crude is any mixture of minerals in the form in which it occurs as a part of the earth’s crust. An ore is a solid crude containing a valuable constituent in such amounts as to constitute a promise of possible profit in extraction, treatment and sale.

The valuable constituent of an ore is ordinary called valuable mineral or often just mineral: the associate worthless material is called gangue. In some ores the mineral is the chemical state in which it is desired by primary consumer, e. g. graphite, sulphur, asbestos, talc, garnet; in fact this is true of the majority of non-metallic minerals. In metallic ores, however, the valuable mineral is rarely the product desired by the consumer, and chemical treatment of such minerals is a necessary step in the process of beneficiation. In such cases the sale product is usually the result of concentration by the method of ore-dressing followed by further concentration by the chemical methods of metallurgy. The valuable product of ore-dressing is called concentrate, the discarded waste material is tailing.

Concentrate is, in most cases, the feed to the metallurgical plant. If the metallurgical processes is one in which separation is effected in melt, the process is called smelting; if the separation is effected by differential or selective solution, the process is leaching or lixiviation.

Metals occur in ores either in the native state (e.g. Au, Ag, Pt, Cu) or as salts or oxides (CuS, Fe2O3, PbCO3), etc. But no matter what chemical form, the metal or mineral is invariably associated with more or less – usually more – barren rock. The form, in which the metal is required by the primary customers, is a relatively pure substance. Hence a more or less extended process of purification, usually involving, in order, ore-dressing, metallurgical extraction, and chemical refining, intervenes between delivery of ore at the mine exit and delivery of the metal to the customer.

One way in which the nonferrous metals differ from iron is the manner of its occurrence. Iron oxides occur in large and comparatively pure deposits; the other metals and compounds from which metals are delivered are scattered through large volumes of rock, such as limestone or quartz. Since it would be difficult and costly to smelt these large amounts of barren rock, metallurgists have recourse to concentration or ore-dressing by which the metals or metallic compounds are partially separated from the gangue or worthless material, before smelting.

Flotation

Flotation is a method of concentrating solid minerals in a relatively finely divided state. It is essentially a method of gravity concentration in water in which the effective specific gravity of certain of the ore minerals is substantially decreased by causing air bubbles to attach more or less tenaciously to particles of that particular mineral, whereupon they float on the separating medium while unaffected minerals sink. When the selected mineral is separated in the form of a froth the operation is called froth flotation.

Подберите термины-синонимы

a) tailing

b) gangue

c) commercial product


 

3. Выберете правильную дефиницию терминов:

«обогащение»

а) добавление ценного элемента в руду;

б) увлечение доли ценного составляющего руды путем удаления пустой породы, песка, глины.

«пульпа»

а) Мягкая, сочная или мучнистая масса, составляющая мякоть плодов.

б) Смесь какого-либо сыпучего, измельченного вещества с жидкостью.

в) Рыхлая, мягкая соединительная ткань, составляющая основную массу селезенки, а также заполняющая полость зуба.

The blast furnace in which smelting is accomplished is a steel shell about 70-80 metres high, lined with fire bricks. The internal diameter varies in the furnace, being about 10 metres at the widest part. Near the bottom of the furnace, air is blown in through nozzles known as “tuyeres”, located at intervals around the furnace. Near the top of the furnace is a passage to carry away the gases produced in the furnace, to be used elsewhere because of their heating values.

A part of the gas from the top is used to preheat the air, which is blown into the furnace though the tuyeres. This is accomplished in three or four stoves which are actually chambers filled with fire bricks. The gases from the top of the furnace are mixed air and coke-oven gases, and pass through the stoves and by combustion, heat up the brick work. When the desired temperature is obtained in the stove, the flow of gas is diverted to another stove in the opposite direction, and into the bottom of the furnace. When the bricks cool, the air is diverted to a hot stove, and the gas again admitted to reheat the bricks.

The blast furnace in operation may be considered as a high column of iron oxide and gangue, coke and limestone, all mixed together but being in individual lumps large enough to allow free passage of the air up through the interstices between the lumps.

Near the bottom of the column where the hot air is blown in there is a high temperature, and the carbon of coke unites with the oxygen of the air to form carbon monoxide, which passes up through the column along with nitrogen from the air:

C+O2→CO

As the carbon monoxide becomes cooler it can unite with more oxygen to form carbon dioxide. To do this, the monoxide takes up the oxygen from the iron oxide, in a comparatively pure state:

Fe2O3+CO→ Fe+CO2

As the material in the bottom of the column is consumed, the charge settles and finally reaches the hot part of the furnace, where the iron is melted and runs down to collect in the bottom of the furnace.

The molten iron is removed intermittently through a hole in the wall of the furnace.The hot gases going up the column heat the limestone and cause it to dissociate into calcium oxide and carbon dioxide:

CaCO3→CaO+CO2

The carbon dioxide escapes with the nitrogen at the top of the furnace, while the hot calcium oxide unites with the gangue to form a liquid slag which flows to the bottom of the column and remains on the top of the liquid iron. As the amount of liquid material in the furnace increases, the slag is draw off through a hole in the wall of the furnace above the iron tap hole. The slag is usually run into large ladles and taken to a granulation basin where the ladles are empted.

The pig iron from the furnace is sometimes cast into mouldsand allowed to solidify so that it can be conveniently transported or stored until needed. More often the pig iron is taken in the liquid state to the refining furnaces for the manufacture of steel.

The starting up or blowing in of a blast furnace is a slow and expensive process, and so once the furnace is operating nothing id allowed to interfere with the regular operation until wear of the lining necessitates shutting down to reline the furnace.During a good run, a blast furnace will produce 10-12 million tons of pig iron before it becomes necessary to reline it.

Прочитайте предложения и их переводы. Какие методики используются для перевода подлежащего (согласно материалам учебники В. І. Карабана. Переклад англійської наукової і технічної літератури. – Вінниця «Нова книга»: 2004 – стр.575)?

The first process in the reduction of an iron ore is smelting in a blast furnace. Доменная плавка является первою ступенью в восстановлении железной руды.
The smelting operation does this and at the same time separates the gangue from the iron. Подобная операция производится посредствам доменной плавки, а также происходит отделение пустой породу от металла.
The blast furnace in which smelting is accomplished is a steel shell about 70-80 metres high, lined with fire bricks. Доменная печь, в которой происходит процесс выплавки, представляет собой конструкцию, состоящую из стального кожуха высотой 70-80 метров, футерованного внутри огнестойким кирпичом.
A part of the gas from the top is used to preheat the air, which is blown into the furnace though the tuyeres. This is accomplished in three or four stoves which are actually chambers filled with fire bricks. Часть колошникового газа используют для подогрева воздуха, который затем вдувают в печь через фурмы. Подогрев воздуха завершается в воздухо-нагревателях, количество которых составляет три-четыре; они фактически являются камерами, футерованными огнестойким кир-пичом.
Near the bottom of the column where the hot air is blown in there is a high temperature, and the carbon of coke unites with the oxygen of the air to form carbon monoxide, which passes up through the column along with nitrogen from the air. В высокотемпературной среде, формирующейся в нижней части шихты – зоне, в которую вдувают горячий воздух, – углерод кокса соединяется с кислородом воздуха и формируется окись углерода. Данное вещество вместе с азотом воздуха поднимается вверх через шихту.

Прочитайте предложения и их переводы. Какие методики используются для перевода сказуемого (согласно материалам учебники В. І. Карабана. Переклад англійської наукової і технічної літератури. – Вінниця «Нова книга»: 2004 – стр.575)?

The blast furnace in operation may be considered as a high column of iron oxide and gangue, coke and limestone, all mixed together but being in individual lumps large enough to allow free passage of the air up through the interstices between the lumps. Доменную печь во время эксплуатации можно сравнить с высокой колонной, состоящей из оксида железа и пустой породы, кокса, известняка. Эти материалы перемешены, но находятся в виде кускового материала одного вещества, что дает возможность воздуху свободно проходить вверх между ними.
During a good run, a blast furnace will produce 10-12 million tons of pig iron before it becomes necessary to reline it. При условии удовлетворительной работы доменной печи в период между футеровочными работами возможно произвести 10-12 милл. тонн чугуна.
The product of the blast furnace is known as pig iron and is used for the manufacture of steel. Продуктом доменного производства является передельный чугун, его используют для производства стали.

Дополните предложения.

a) The rolls are made of ______ or _______.

b) The roll has two _____, on which the rolls revolves on bearings and a ________, on which the rolling is accoumplished.

c) For rolling plates, slabs and sheets, ___________ rolls are applied.

d) For rolling billets, bars and sections, ___________ rolls are used.

e) The roll grips the metal due to a force of ___________.

Дайте определения терминам.

Прокат

Прокатка

4. Переведите термин и объясните его значение на английском языке.Macro structure

Переведите диалоги.

a) - What is rolling?

- Прокатка – это обработка металла давлением. Валки расположены таким образом, что расстояние между ними меньше, чем толщина задаваемого металла.

- What is a principle object of rolling?

- Основной целью прокатки является слом грубой структуры металла.

- What is one the most important problems in rolling?

- Экономия металла. Экономия металла может быть достигнута использованием облегченных профилей и профилей высокой точности.

 

b) - How rolls are classified?

- The rolls may be plain or grooved. The larger rolls of the 4-high roll stand do not have a contact with metal and are called back-up rolls. The back-up rolls support the working rolls in operation and reduce their elastic deflection.

 

Прочитайте текст до та зробіть завдання до нього.

Ores

A crude is any mixture of minerals in the form in which it occurs as a part of the earth’s crust. An ore is a solid crude containing a valuable constituent in such amounts as to constitute a promise of possible profit in extraction, treatment and sale.

The valuable constituent of an ore is ordinary called valuable mineral or often just mineral: the associate worthless material is called gangue. In some ores the mineral is the chemical state in which it is desired by primary consumer, e. g. graphite, sulphur, asbestos, talc, garnet; in fact this is true of the majority of non-metallic minerals. In metallic ores, however, the valuable mineral is rarely the product desired by the consumer, and chemical treatment of such minerals is a necessary step in the process of beneficiation. In such cases the sale product is usually the result of concentration by the method of ore-dressing followed by further concentration by the chemical methods of metallurgy. The valuable product of ore-dressing is called concentrate, the discarded waste material is tailing.

Concentrate is, in most cases, the feed to the metallurgical plant. If the metallurgical processes is one in which separation is effected in melt, the process is called smelting; if the separation is effected by differential or selective solution, the process is leaching or lixiviation.

Metals occur in ores either in the native state (e.g. Au, Ag, Pt, Cu) or as salts or oxides (CuS, Fe2O3, PbCO3), etc. But no matter what chemical form, the metal or mineral is invariably associated with more or less - usually more - barren rock. The form, in which the metal is required by the primary customers, is a relatively pure substance. Hence a more or less extended process of purification, usually involving, in order, ore-dressing, metallurgical extraction, and chemical refining, intervenes between delivery of ore at the mine exit and delivery of the metal to the customer.

One way in which the nonferrous metals differ from iron is the manner of its occurrence. Iron oxides occur in large and comparatively pure deposits; the other metals and compounds from which metals are delivered are scattered through large volumes of rock, such as limestone or quartz. Since it would be difficult and costly to smelt these large amounts of barren rock, metallurgists have recourse to concentration or ore-dressing by which the metals or metallic compounds are partially separated from the gangue or worthless material, before smelting.

Flotation

Flotation is a method of concentrating solid minerals in a relatively finely divided state. It is essentially a method of gravity concentration in water in which the effective specific gravity of certain of the ore minerals is substantially decreased by causing air bubbles to attach more or less tenaciously to particles of that particular mineral, whereupon they float on the separating medium while unaffected minerals sink. When the selected mineral is separated in the form of a froth the operation is called froth flotation.









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