Question

Which furnace is used for roasting and calcination????

Answer 1

Answer:

Reverberatory furnace.

Answer 2

Answer: Calcination and roasting take place in a reverberatory furnace that is shaped like a horizontal ‘S’ and may be used with or without oxygen.

To understand the concept better, we need to know more about calcination and roasting.

Explanation:

What is Calcination?

• Calcination is a technique that involves heating a solid object or chemical in a controlled atmosphere.
• Temperature is usually controlled during the procedure.

• Calcination is used to modify the physical or chemical composition of a material.
• Solids are heated to extreme temperatures during calcination.
• This is done primarily to remove volatile chemicals, remove water, or oxidise the material.
• This procedure is also known as a purifying procedure.

Examples of Calcination

• Calcination of limestone includes the breakdown of carbonate ores as well as the removal of carbon dioxide.    

                                       CaCO₃ → CaO + CO₂

• During iron calcination, anhydrous iron is generated.

                                 2Fe₂O₃.3H₂O → 2Fe₂O₃ + 3H₂O

• Calcination of gypsum and bauxite, which involves the removal of water from crystallisation in the form of water vapour.

                             CaSO₄.¹/₂H₂O + heat → CaSO₄.¹/₂ H₂

What is Roasting?

• Whenever we think about roasting, we’re talking about a metallurgical process in which ore is heated beyond its melting point with in condition of extra air and then transformed into its oxide.
• Roasting is a method of converting sulphide ores.
• During roasting, metallic impurities are released as volatile gases.
• The roasting process is made up of solid-gas thermal reactions include reduction, oxidation, pyro hydrolysis, sulfonation, and chlorination.

Examples of Roasting

• Roasting mercury sulfide (HgS) may result in the release of free mercury (Hg) metal.
• Roasting zinc sulphide (ZnS) can result in zinc oxide (ZnO).

What is Reverberatory furnace?

• A reverberatory furnace is a type of furnace that is primarily used for the extraction of metals such as copper, tin, nickel, and aluminium, as well as the manufacture of certain cements and concretes.
• These materials are mostly smelted and refined in the furnace.

Design of Reverberatory furnace

• Today’s reverberatory furnace is mostly made out of a rectangular steel box lined with castables with non-wetting qualities or refractory bricks.
• A vertically raising door is located at one end of the furnace, while burners are often located opposite the burners.
• Roofs are also composed of the same refractory brick, which is robust and helps create greater temperatures, resulting in faster refining.
• However, when new technological advancements emerge, they change and improve not just the fundamental building materials, but also the furnace’s output capability.

Operation of Reverberatory furnace

• In terms of operation, heat is typically transferred across the hearth, which contains the ore combination, in a reverberatory furnace.
• Emission from the refractory bricks in the walls and roof is the primary mode of heat transmission.
• The ore is given additional heat by the burner.
• The furnace’s ceiling is likewise somewhat arched and stays tilted towards the bridge of flues that deflects the flame for reverberation.
• Until the mixture melts, it is continually heated.
• Simultaneously, the molten contaminated metal is gathered in the hearth, which in itself is thick and built of a robust substance that can also withstand slag disintegration.