What is meant by Bayers process?
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What is meant by Bayers process?
Definition of Bayer process : a process for producing alumina from bauxite by digesting it in hot sodium hydroxide solution.
What is clarification Bayer process?
Bayer process is the process of refining alumina from bauxite (aluminum ore containing 30-50\% of hydrated aluminum oxide) by selective extraction of pure aluminum oxide dissolved in sodium hydroxide. Prior to the Bayer process bauxite is crushed and ground in mills to fine particles (max. size 0.06”/1.5mm).
Is the Bayer process expensive?
The Bayer process involves dissolving the alumina present in bauxite in a caustic solution at high temperature and pressure. After the undissolved impurities are removed, the solution is seeded to produce an alumina trihydrate precipitate. The estimated operating cost is approximately $250 per ton of alumina.
How do you process bauxite?
The Bayer Process Bauxite ore is dissolved in sodium hydroxide, or lye, at a high temperature and pressure. Then, the alumina and bauxite ores are separated by washing out the waste (red muds or sands) from the alumina.
Which solution is used in Bayer’s process?
In the Bayer process bauxite is crushed, mixed in a solution of sodium hydroxide, and seeded with crystals to precipitate aluminum hydroxide.
What is red mud in Bayers process?
Red mud, now more frequently termed bauxite residue, is an industrial waste generated during the processing of bauxite into alumina using the Bayer process. It is composed of various oxide compounds, including the iron oxides which give its red colour.
What is the anode and the cathode used in Bayer process composed of?
The diagram shows an aluminium oxide electrolysis cell. Both the negative electrode (cathode) and positive electrode (anode) are made of graphite, which is a form of carbon.
How is a sodium hydroxide liquor used in the Bayer process?
In the Bayer process, prepared bauxitic ore is digested under pressure in a hot aqueous solution of sodium hydroxide and then ‘seeded’ to induce precipitation of Al(OH)3 crystals, usually referred to by the mineral term ‘gibbsite’.
What is the difference between alumina and bauxite?
Bauxite is a more general term for a piece of rock made of oxides of hydrated aluminum. It is the primary ore of alumina, which is used to make the actual aluminum. This ore is also utilized in making aluminous refractories and synthetic corundum. In this connection, aluminum is a very ductile element.
Why is bauxite purified?
Extraction of aluminium The bauxite is purified to produce aluminium oxide, a white powder from which aluminium can be extracted. The ions in the aluminium oxide must be free to move so that electricity can pass through it. Aluminium oxide has a very high melting point (over 2000°C) so it would be expensive to melt it.
Why is NaOH used in Bayer’s process?
The bauxite is purified by the Bayer Process. First the ore is mixed with a hot concentrated solution of sodium hydroxide. The NaOH will dissolve the oxides of aluminum and silicon but not other impurities such as iron oxides, which remains insoluble. The insoluble materials are removed by filtration.
What is red mud used for?
Several studies have been conducted to develop uses of red mud. An estimated 3 to 4 million tonnes are used annually in the production of cement, road construction and as a source for iron.