FVAC versus LYC, page-9

You need to recheck your facts on the HRE content at Mt Pass vs Mt Weld.
Here's a tabulation (source Tech Metals Research):

Resource	Relative Distribution (as % of total RE)
	Nd/Pr	Dy	Tb
Mt Pass	16	0.05	0.06
Mt Weld CLD	23	0.09	0.25
Mt Weld Duncan	23	1.3	0.26

So as a proportion of their Nd/Pr production, Lynas will product about 4x as much Tb and between 2 and 3x as much Dy depending on the blend of Duncan/CLD they use.
The Lynas production is roughly in line with usage in the magnet business, Mt Pass falls well short until they find ways to use less HRE.