[Ntripleb]

I have a question why cant aluminum just use the process of "self reduction" like lead does, and remove the O3 from bauxite?
going from AlO3 --> Al2 +O3 ?? so confused!!

[adianadiadi]

Al₂O₃ has strong affinity with oxygen and it is highly exothermic compound.

Though you can write reactions as you wish theoretically, it is always not feasible to carry out those under real conditions. The reactants must be thermodynamically feasible and must surpass the kinetic energy barrier.

Hence electrolysis method is used instead in this case.

[rabolisk]

Al₂O₃ has strong affinity with oxygen and it is highly exothermic compound.

Though you can write reactions as you wish theoretically, it is always not feasible to carry out those under real conditions. The reactants must be thermodynamically feasible and must surpass the kinetic energy barrier.

Hence electrolysis method is used instead in this case.

[adianadiadi]

exothermic compound is that for which the heat of formation is negative.

[vmelkon]

Self reduction for lead? How would that be done? Which oxide?

[Ntripleb]

when galena turns to lead it goes through a few small processes
Froth flotation.. which has a no chemistry
Roasting
2PbS + 3O2 --> 2PbO + 2SO2
Self Reduction
PbS + 2PbO --> 3Pb + SO2

HINT: my chemistry knowledge is pretty low, so the equations are dummed down as low as then can go

[vmelkon]

Well, there is a big difference between that and

PbO => Pb + 1/2O2

[Ntripleb]

okay my assignments due tomorrow, could someone tell me if all of this is chemically correct?

Bauxite does not use self reduction in its first initial process. The reasoning of this is because of bauxite high affinity with oxygen and because it is a high exothermic compound, which means large amounts of voltage (energy) are required to pass through the compound too separate the aluminium from the oxygen. The self reduction process cannot produce this high amount of energy because the reactants aren’t as thermodynamic as bauxites, meaning the energy barrier is too high for the process to occur, hence why the process of electrolysis is used. Electrolysis reaches the energy barrier, allowing the separation of Aluminium and oxygen to occur. Companies would like to use Self reduction because of the energy saved during the process. If self reduction was used the bauxite ore wouldn’t go through the process of electrolysis which requires high levels of energy to separate the aluminium from the oxide which would save processing companies money. This process would also remove all carbon emissions created during the electrolysis process.

[vmelkon]

Bauxite is not a "high exothermic compound". Only chemical reactions can be qualified as exothermic or endothermic.

"large amounts of voltage"
The process requires very little voltage. They use between 4 to 8 V.
They do use high amounts of current, perhaps 10,000 A or 100,000 A.
Voltage does not represent energy. Energy is measured in Joules which is calculated as Volt * Amps * time_in_seconds.

Keep in minds that those are very large electrolytic baths with huge electrodes and that is why so much current passes through them. Of course, you can build a small one that consumes 1 A at home if you want.

Electrolysis is a slow process but it produces highly pure elements. It is used for a lot of other elements as well.

There are several reasons that electrolysis is used for aluminum and as you said, one of them is because aluminum's reactivity.

"Companies would like to use Self reduction "

I don't think that Al2S3 is available for one thing.
Besides, I'm sure that it has be researched A LOT and that other possible routes have been considered.