Fuels and furnaces mineral beneficiation Quiz-2

Answer: a
Explanation: When a metal undergoes solidification, it undergoes a decrease in volume which is called contraction and hence is it is a major parameter in the metallurgical transformation which is taken into consideration while designing any component for foundry applications.

Answer: b
Explanation: Olivine is refractory sand. When packed as the mold cavity, they remain sufficiently porous or permeable to give vents to the mould gases to escape out. Hence they are chemically immune and can be molded in intricate shapes.

Answer: d
Explanation: The cores are made with recesses and projections so that they can be fitted together to make a mould. Hence, a core sand mould is said to be an assembly of such components.

Answer: b
Explanation: In the Strickle core box, the top portion is done by the strickle board cut. It strikes off the excess sand. A regular, irregular or the unsymmetrical shape is difficult to produce on core box but can be cut on wooden strickle board. Hence it costs less.

Answer: d
Explanation: Amine gas and sulphur-di-oxide gases are used at high temperatures where the core boxes are made of wood and plastic. The carbon-di-oxide gas is used as a casting core binder in sodium silicate. Marsh gas does not find any applications in the cold-box process.

Answer: b
Explanation: Pickling is one of the methods used in chemical cleaning of the castings manufactured. Pickling makes use of dilute acids for removing sand from the surface and inaccessible pockets of the castings. Hence, there is a danger of retaining a little amount of acid.

Answer: c
Explanation: Top gate is the one in which the molten metal always drops to the bottom of the mould. Hence, finger gate, wedge gate and a ring gate perform such function whereas the horn gate is a bottom gate.

Answer: a
Explanation: Molding machines have patterns fixed on them which have inbuilt gating system and runner, gate etc that are mounted on the match plate itself. They perform their action rapidly and more accurately than the other types of molding.

Answer: a
Explanation: Pit furnace has a limited capacity. It is used to melt a certain low amount of metal to produce castings. Only small castings can be produced. Hence, it is often used with permanent moulds and die casting machines.

Answer: a
Explanation: Coreless induction furnace consists of two types of coils; primary and secondary coil. The wall of the container forms the secondary winding and the iron core links the primary as well as the secondary coil. This is the principle of the transformer as well as induction furnace.

Answer: d
Explanation: The coke has excellent burning properties and can be used to melt iron easily. Coke is always supplied in low quantities so that it can produce enough heat to melt the iron and the pollution making factor for the coke is relatively less.