Australian Bauxite Limited (ASX:ABZ) Taralga Bauxite Resource Doubled To 25 Million Tonnes
Sydney, May 12, 2011 AEST (ABN Newswire) - Australian Bauxite Limited (
ASX:ABZ) has 33 bauxite tenements in eastern Australia covering more than 7,500 km2.
To clarify the marketability of the bauxite types found in the Taralga-Goulburn-Crookwell area in southern NSW, detailed drilling was recently conducted at spacings of approximately 100 metres in areas containing easily mined bauxite zones of Direct Shipping Ore ("DSO") grades because Taralga is located near a major railway line leading directly to Port Kembla export terminal.
Two main bauxite types are recognised at Taralga as shown in Figure 1 (see link at the bottom of the release), namely:
1. Gibbsite rich, low silica bauxite that will be the main component of direct shipping ore (DSO);
2. Pisolitic, dehydrated hardcap bauxite, often forming a surface hardcap layer 2 metres thick .
Each bauxite type can have quartz-rich zones where quartz grains have mixed with the bauxite.
Resources at Taralga based on drilling to date can be summarised as follows (see link at the bottom of the release):
This DSO gibbsite ore is considered to be the main type of bauxite in the Goulburn-Taralga-Crookwell district.
2. 10 million Tonnes of Pisolite Ore
In many locations, there is a 2 metre thick surface layer of "Pisolite Ore" above the main gibbsite bauxite.
This is pisolitic (rounded gravels), iron-enriched, dehydrated bauxite which is cemented into a hardcap layer in places.
Note that this material has elevated levels of iron (Fe2O3) and low loss-on-ignition (LOI) which indicates dehydration. Note also that 15% of the alumina (Al2O3) does not report as available Al2O3 at the leach temperatures used here. At moderately higher leach temperatures, it is expected that more of the total alumina would report as being available Al2O3. This will be tested as part of metallurgical testwork scheduled for June-July.
3. 5 million Tonnes of Quartz-Bearing Bauxite
At depth and laterally, both major bauxite types can become quartz-bearing bauxite in the form of sand grains and small layers of quartz-rich gravels mixed with bauxite. In places, this material is peripheral to the main deposits.
The major bauxite deposits in the Darling Ranges bauxite-alumina projects south of Perth, Western Australia are quartz-bearing and there are many similarities between the bauxites of the Eastern Australian Bauxite Province and the WA Darling Ranges bauxites.
Quartz is an inert, non-reactive form of silica (SiO2) which does not affect the processing of the bauxite into alumina and aluminium. However, it does dilute the grades of the bauxite as shown by the following tables (see link at the bottom of the release).
Note that total silica (SiO2) is approximately 20% in these bauxites, but only 1.9% to 3.1% is reactive silica.
RESOURCE ESTIMATE METHOD
Drilling on a random pattern governed by site availability was done predominantly in the northeastern parts of EL 7357 where bauxite plateaus were obvious and some in the southwestern parts of EL 7357 where unexpectedly thick, good quality bauxite was discovered in late 2010.
During August 2010, 98 holes were drilled totalling 710 metres and during September-October 2010, a further 112 holes were drilled totalling 985 metres. Infill drilling done during the first Quarter of 2011 brought the total drilling at Taralga to 577 drillholes totalling 4,575 metres drilled.
Drill samples were collected at 1 metre intervals from the aircore drillholes and analysed at ALS Laboratories in Brisbane including trihydrate (THA) available alumina (Avl Al2O3) and reactive silica (SiO2 Rx) measurements. Leach conditions to measure available Avl Al2O3 and reactive SiO2 Rx were 1g leached in 10ml of 90gpl NaOH at 143 degrees C for 30 minutes Estimation of grades and thicknesses was done by an inverse distance squared modelling method using maximum extrapolations of 100 metres for Indicated Resources category and 150 metres for Inferred Resources. Bauxite density was conservatively assumed at 1.8 dry tonnes per cubic metre in-situ.
For the complete Australian Bauxite Limited announcement including figures and tables, please refer to the following link:
http://www.abnnewswire.net/media/en/docs/634237.pdf
About ABx Group Limited
ABx Group Limited (ABx) (ASX:ABX) is a uniquely positioned Australian company delivering materials for a cleaner future.
The three priority projects are:
- Heavy rare earths: Supplying light and heavy rare earths from Tasmania into Western supply chains
o Processing Options Analysis conducted in partnership with external experts
- Clean fluorine chemical production: Producing industrial chemicals from aluminium smelter by-product (ALCORE)
o Continuous pilot plant under construction in Bell Bay, Tasmania
- Near-term bauxite production: Mining bauxite resources for the aluminium, cement and fertiliser industries
o Agreements executed with Good Importing International for bauxite projects in Queensland and New South Wales, and $2.7 million initial payment has been received
o Approvals well advanced for DL130 bauxite project in northern Tasmania
ABx endorses best practices on agricultural land and strives to leave land and environment better than we find it. We only operate where welcomed.
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