Resumen de AMCOL Australia's Gurulmundi mine: A leading supplier of high quality sodium bentonites
Industrial Minerals
Amcol Australia's sodium bentonite mine is located near Gurulmundi, 40km north of Miles, some 350km inland of Brisbane in Queensland, eastern Australia, in an area where bentonites were first reported in the 1960s (Exon and Duff, 1968). Geologically, the bentonite deposits are hosted by the Orallo Formation of the Jurassic/Cretaceous Surat Basin, which straddles southeast Queensland and northern New South Wales.
The Orallo Formation is located within the upper part of the Surat Basin and comprises clayey lithic sandstone, siltstone, minor mudstone and bentonite, deposited within a high energy fluvial/lacustrine to coastal plain and shallow marine environment. The contact between the Orallo Formation and the Mooga Sandstone is characterised by bentonite beds in the upper Orallo Formation, overlain by a laterally discontinuous polymictic conglomerate at the base of the Mooga Sandstone. Silicified fossil wood is fairly common in sandstones and conglomerates of the Orallo Formation above the bentonite. The rock strata strike northwest and generally dip at 2 to 3[superscript]o to the southwest.
Amcol Australia has determined bulk density on several of the Gurulmundi bentonites by core drilling and the 'calliper method' as described by Lipton & Horton, 2014. Accordingly, the ends of the core sample are cut with a saw perpendicular to the long axis of the core to create a regular cylindrical sample. The diameter of the core is determined with a pair of callipers at several points and the results averaged. The length of the core is determined with a ruler and the volume calculated. The mass of the solid is determined by weighing the core. Then by using weight/volume the ISBD is derived, which in the case of 5D light olive gray bentonite A 1.8 tonnes/m[superscript]3 (A 112 lbs/cubic foot).This number has recently been validated by reconciling tonnes 'hauled' with in-situ tonnes modelled, over several mining campaigns.
