Let's start with the following numbers :
- 3 billion tons already stocked
- 120 million tons produced every year
- a red mud plant the size of the planned SGA plant would use 2.4 million tons every year
It would take 25 years for 100 such red mud plants to clear the planet while treating the yearly rejects if those would stay the same as they are now AND if all the plants began operating simultaneously, like now.
This is of course a completely abstract construct, but it does give an idea of the size of the thing.