So it should work this way Mega. The customer is offered or...

So it should work this way Mega. The customer is offered or specified what product is available. Lets say SC6 is desired in this case. 6% Li2O
The grade of ROM bears no impact when defining the grade that is required out of the concentrator. You could put out SC6 or SC5.5 (Like PLS) if thats the desired product.
How much R.O.M required to achieve that grade changes depending on the Li2O content.

Lets say just for argument sake that all of NAL is 0.94% Li and all of Authier is 1.1% Li

Ok, we run both those ores through the same facility separately without changing any of the settings.

If you needed to concentrate 150,000t of NAL's 0.94% ROM to achieve 18,750t of SC6 then:

You would need only 126,000t of Authier's 1.1% Li ROM to achieve the same result with the exact same parameters through the crusher/concentrator.

Alternatively we could achieve the desired grade of spod by concentrating NAL's low grade or for LONGER... but we dont want that because... you guessed it, that would slow down production.

So.. given that we have one month's ROM up our sleeve, that could be sifted into lower/higher grade batches to optimise output, especially early in the delivery schedule.

You could run the higher grade ore through first, achieve the desired production, then, because let's face it, we arent going to throw the low grade stuff away, because it takes longer to process, and we still need to recover it's mining cost so we are going to chuck that through the processing plant at the end of each month or each year depending on the output.

Lets say, we work out in April 2024 that we are going to produce 240,000t of SC6... we could scale back the production by using the lower content ore, produce 226,000t instead ( because let's face it, anything more is just split with PLL, which is ok, but why do it if we dont have sale of it anyway) The lower grade stuff needs to be used somewhere, and that's how to do it.

Then of course, for delivery in Q3 2024 - we get back onto the higher grade ore.

All in my opinion. The numbers are estimates. And all of this is how i would do it if the Cat was running the branch.