bauxite grades weipa vs darling ranges

Interesting comparison on grades of bauxite - Weipa vs Darling Ranges. Clearly Weipa is the better grade - link for those interested -> http://www.aluminium.org.au/Page.php?d=1009


Mineralogy
Weipa bauxite ore occurs naturally in pisolitic (pealike) form. The bauxite consists mainly of 55 per cent aluminium trihydroxide (also called gibbsite) and 14 per cent aluminium hydroxide also called boehmite


Mineralogy
Darling Range bauxite is a low-grade ore with around 27-30 percent aluminium oxide. Deposits typically consist of half a metre of topsoil and overburden, which is removed and conserved for later rehabilitation. The caprock bauxite (generally 1 to 2 metres) is drilled and blasted before extraction with the more friable bauxite below. It is the lowest grade ore mined on a commercial scale anywhere in the world, requiring substantial investment in a fleet of loaders, excavators and trucks as well as crushing and conveying equipment