Dear Dr. M P Sharma

The abstract of the article titled "Oxygen-enhanced combustion provides advantages in Al-melting furnaces" by Stewart Jepson and Peter Van Kampen is very helpful in that it cover a valuable answer for the first part of your inquiry as found in the following RG link.

Article Oxygen-enhanced combustion provides advantages in Al-melting furnaces

The details information on the second part of your question are found in the Chemguide's text on the following link.

https://www.chemguide.co.uk/inorganic/extraction/aluminium.html#:~:text=Instead%2C%20it%20is%20extracted%20by,to%20electrolyse%20on%20its%20own.&text=The%20usual%20aluminium%20ore%20is%20bauxite.

Best regards