The generally accepted ratio of spodumene 6% to Carbonate is 8:1...

The generally accepted ratio of spodumene 6% to Carbonate is 8:1 as stated by A/C which is basically based on stoichiometry being about 7:1 and then allowing for some loss in the processing.

Spod ore to concentrate will depend on the grades. If you are using 1.5% grade DSO and getting 50% recoveries it would probably be about 8:1 also giving a total of 64:1

However given galaxy have been tuning their plant to their own ore for over 6 months and are only at 54% recoveries the mica setup of the chinese plants might only get 30-40% recovery. In this case you are looking at 10-12:1 for your conversion which is about where A/C landed.

The easiest way to work this out is essentially 6% / (input grade * recovery). So in the examples above 6.0%/(1.5%*40%) = 6.0%/0.6% = 10.

Hope this helps