"We view Atlantic as one of the highest quality hard-rock...

"We view Atlantic as one of the highest quality hard-rock developers globally.

There was an interview with Len Kolff their Chief Geologist last July - well worth listening to.
Len described the reasons why Atlantic's deposit is one of the highest quality deposits.

Firstly it is low in Impurities like iron. In the Kiln these melt into a slag and stick to the sides of the Kiln, each couple of weeks the Kiln needs to be shut down and the slag removed. These Kilns run at 1000deg, so the fewer times they need to be shut down the better.

Secondly 95% of their ore is coarse grained and has a low work index making it suitable for DMS.
Work Index measures how hard the pegmatite is, if it is very hard it tends to shatter when put in the primary crusher creating a lot of fines not suitable to DMS (as opposed to something like sandstone which tends to crumble). Both Leo's Goulamina and LTR's Kathleen Valley have coarse large crystals but have a high work index which is why they both use Whole of Ore Flotation (WOF). PLS use a combination of both.

Being able to use DMS instead of flotation or a combination of both has many advantages.
The Converters prefer the coarse grain compared to fines.
Capex is about half that of WOF
This is because of several factors, the plant capex is cheaper, you don't need a tailings facility - the rejected rock is simply treated as waste rock - it isn't contaminated.
Opex is cheaper, lower power use, reagents not required etc.

There is also a misconception that producing SC6 as opposed to lower percentages (eg SC5.5) is superior. Len points out that producing higher % spod means more spod is rejected to tailings, every ore body & concentrating plant has a sweet spot where producing lower grades enables a higher volume. Of course some mines/plants struggle with grade for other reasons (recovery rates, in Mt Marion's case the basalt in the ore body)