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Right OPTION is (b) False

Best explanation: Gas reverberatory furnaces are generally USED for MELTING the non-ferrous metal in the casting foundries, as they gives large reservoir of liquid metal and ensures steady and reliable supply of metal to the foundry SHOP. So that, many large and medium sized foundry shops use them as CENTRAL melting system.

Correct answer is (B) CAST IRON

Explanation: The bottom being the legs of the cupola are MADE up of cast irons, also the DOORS for bottom opening of cupola are made of cast iron only.

Correct CHOICE is (c) 12 tons

The best EXPLANATION: A high frequency induction furnace is used for the MELTING of comparatively small QUANTITIES. METALS up to the mass of 12 tons can be melted using this process.

Correct option is (b) False

The explanation: The PROCESS of melting is done very quickly by conduction and radiation, and magnetic stirring MAKES uniform DISTRIBUTION of the melt composition, which reduces time. Hence time TAKEN by the charge to melt is SHORT.

The correct choice is (c) Alternating secondary currents

Explanation: A HEAVY amount of alternating secondary current, by ELECTROMAGNETIC induction, is INDUCED in the metal charge. This causes the metal to get heated, because of the RESISTANCE OFFERED by the metal charge.

Right choice is (a) Causes overheating

To EXPLAIN: In an indirect electric arc furnace, the rocking of furnace causes the melting to SPEED up, it ALSO causes uniform composition of melt and does some DAMAGE to the refractory lining. This process does not CAUSE overheating, instead it avoids it.

The correct answer is (a) True

To elaborate: To be operating in a basic REFRACTORY, it is advantageous as the INFERIOR scrap can be used for the production of good quality STEEL. HENCE, basic REFRACTORIES are costlier than acid refractories.

The correct option is (a) Silica

For explanation: A very heavy steel shell is EQUIPPED in making the roof, with the HELP of refractory bricks. To this, silica is added when the FURNACE is acid lined.

Correct answer is (b) False

Easy explanation: In crucible furnaces, there is no DIRECT collision of flame on the material. And the heat LOSS to the outside SURROUNDING is restricted by the refractory walls. HOWEVER, the energy efficiency of the crucible furnace is low with approximately 60% of the heat loss affected by the radiation and the temperature control is ALSO very difficult in the crucible furnaces.

The correct answer is (C) Tool steel

The BEST I can explain: The crucible process is used for the production of tool steel. Hammered iron which had rich carbon content in it was FIRST used for PRODUCING tool steel.

The correct choice is (B) 3 hours

Explanation: The PROCESS of lighting is starting the CUPOLA and firing it for about 3 hours, a little before the metal is needed for pouring.

Correct OPTION is (a) True

Explanation: Oxidation of carbon and oxidation of manganese are both exothermic reactions, that is, these reactions LIBERATE HEAT. But, oxidation of manganese or silicon LIBERATES more heat than oxidation of carbon.

The correct CHOICE is (c) Pig iron

Easiest explanation: Inside the FURNACE, before beginning the ACTUAL process, the pig iron is charged. Above this charged pig iron, the scrap is then placed.

Correct choice is (a) Radiation-conduction

For explanation I would say: In a rocking furnace, the HEAT is first radiated from the hot refractory walls and the ARC and conduction when the furnace STARTS rocking from the WALL lining.

Correct CHOICE is (b) Copper

The explanation is: An indirect ELECTRIC arc furnace cannot be USED for melting zinc, but for melting steel, cast IRON or copper and its alloys, this method can be used.

The correct option is (b) False

Easiest explanation: The ELECTRIC arc furnaces are widely used for MAKING steel metal, it basically consists of a water cooled ROOF which shapes like a SECTION of a sphere. These furnaces also include graphite electrodes which normally ENTER into the furnace through the roof which can be refractory lined or water cooled.

The CORRECT option is (a) True

Best explanation: Production of crucibles is a very INEXPENSIVE PROCESS. It does not include much capital and the INSTALLATION costs are also not very high.

The CORRECT choice is (c) BUNGS

To explain I would say: The question MARK in the picture is depicting a few bungs. These bungs insure the PROPER charging of the metal. The given figure is that of an AIR furnace or a reverberatory furnace.

Correct answer is (c) Tensile strength of the steel

To elaborate: In the acid-cupola REACTION, the SULPHUR CONTENT is always increased. This INCREASE in the sulphur content depends on quantity of coke, quantity of steel, the slag BASICITY, but not the tensile strength of steel.

Correct answer is (C) 1492°C

The best I can explain: In the iron – iron carbide DIAGRAM, or the Fe-Fe3C equilibrium diagram, the peritectic transformation OCCURS at a very high temperature. The temperature POINT of peritectic reaction TAKES place is 1492°C.

The correct CHOICE is (a) True

The best explanation: The combustion section of the cupola furnace is also known as oxidizing zone. It is generally LOCATED between the upper part of the tuyeres and a theoretical level above it. The maximum height of this section can be up to 30 cm. The combustion takes place in this section by TAKING the free oxygen completely from the air and generating ABUNDANT heat.

Right choice is (b) 60%

Best EXPLANATION: As COMPARED to a core type FURNACE, a coreless HIGH frequency induction furnace has a lower efficiency. The thermal efficiency of a coreless furnace can be only up to 60%.

The CORRECT choice is (c) MAGNETIC stirring

Explanation: For ensuring uniformity, a magnetic stirrer is EMPLOYED, in a high FREQUENCY induction furnace. This magnetic stirrer distributes the composition of the melt excellently as needed.

Correct answer is (b) False

To EXPLAIN I would say: Energy losses from the surfaces are large DUE to the large surface area to volume RATIO of the electric furnaces that results in ABUNDANT energy losses during the operation of melting metals. These losses also arise through the refractory walls and ROOF due to the large surface area of the furnace.

The CORRECT answer is (c) TRUNNION for tilting

To explain: The question MARK is representing a trunnion. This trunnion is used for tilting the entire apparatus, which is giving the required ANGLE to the side blown converter.

Correct OPTION is (b) CYLINDRICAL

The explanation is: The ROTARY melting furnace is a cylindrical shell made up of STEEL shell. The rotary melting furnace is used for rotating or ROCKING purposes.

Right OPTION is (a) 10%

The EXPLANATION: There is no such method in existence which will be ABLE to tell us the AMOUNT of sulphur pick-up. But, the lowest amount of sulphur pick-up in acid-cupola REACTION should not be more than 10%.

Right CHOICE is (c) 15%

For explanation: During METALLURGICAL control, the amount of MANGANESE LOST is about 15%. This loss takes place because of the presence of oxygen, that is, an oxidation reaction takes place.

The correct ANSWER is (a) Molten iron

The BEST I can explain: Inside the WELL of a cupola, there is molten iron COLLECTED. The well is positioned in between of bottom of tuyeres and tapered ram sand bottom.

The correct CHOICE is (a) True

Easy explanation: A cupola is basically a CYLINDRICAL metal shell which is either welded or RIVETED to the boiler plate. It is MAINLY open at the TOP.

Right choice is (b) False

The explanation is: CUPOLA does not have a specific TIME duration of the operation. HENCE, there is no uniform QUALITY in the PRODUCTION of metal.

Right choice is (d) ZINC

The explanation: Among the following, zinc cannot be operated through cupola furnace, WHEREAS the IRONS, COPPER base alloys and some kinds of bronzes are operated using a cupola furnace.

The correct option is (b) False

Explanation: In resistance furnace, a current is passed through the charged material which results in HIGH resistance that further causes heating of the charged material. The heating is MAINLY DUE to the radiation from the heating material. And fuel gases like propane, acetylene or natural GAS are mainly used in oxy-fuel furnaces in which OXYGEN is combined with these gases to generate heat.

The correct answer is (a) True

The best I can explain: Induction melting produces very less fumes than that produced by the melting in an electric arc furnace or cupola melting FURNACES. It is very EASY to ACHIEVE melt composition in induction melting. And induction melting is very sensitive to the QUALITY of materials used as compared to the cupola or electric arc melting furnaces.

Right choice is (a) True

The best I can explain: The flue GASES from the fuel makes direct contact with the metals used in the furnace, the type of fuel SELECTED is very important. For example, many metals cannot tolerate sulphur in the fuel. Solid fuels basically create particulate matter which can INTERRUPT the metal placed inside the furnace. To avoid this PROBLEM, GASEOUS or liquid fuel is used in the place of solid fuels.

Right option is (a) True

The best explanation: In electric furnaces, the process of de-slagging is mainly carried out to REMOVE the slag IMPURITIES from the furnace. During the refining process, some of the undesirable metals are oxidized and enters into the slag PHASE. So the furnace is TILTED to pour out the slag from the furnace through the slag DOOR.

The correct choice is (c) Tapping

Easiest explanation: The ELECTRIC furnace is generally BUILT on a TILTING plane so that the molten metal can be poured into another CONTAINER for transportation. The process of tilting the furnace to pour the molten metal is known as tapping. Electric ARC furnaces are widely used only where there is plentiful electricity.

Correct option is (B) False

For explanation I would say: Crucible FURNACE is not an expensive MELTING method, it is a very cheap method of melting the metal and it is mainly preferred for melting small volumes of non-ferrous MATERIALS. It is very popular in jobbing and die casting foundry shops because tapping and charging process is very easy with another TYPE of alloy.

The correct choice is (a) 5 TONS

Easy explanation: OPEN hearth process was PRIMARILY used only for steel MAKING, it was later brought to use in steel FOUNDRIES. The minimum capacity of open hearth furnace in steel foundries is 5 tons.

The correct answer is (b) False

For explanation: The open HEARTH furnace had this as ONE of its LIMITATIONS, that the PROCESS was time consuming. It took more time than basic oxygen furnace and electric ARC furnace.

Right answer is (a) 15CM to 30cm

Easiest explanation: For SUPERHEATING, combustion or OXIDIZING zone, the cupola is generally SITUATED at the top, approximately 15cm to 30cm above the tuyeres.

The correct option is (a) True

The best I can explain: Any CORE type furnace is primarily used for remelting of non-ferrous METALS and their respective alloys. But a low frequency induction furnace may be used if malleable CAST IRONS are to be produced.

The correct option is (C) 70%

To EXPLAIN: In a direct arc furnace, the analysis of the melt can be accurately calculated and its efficiency can go as HIGH as up to 70%.