test work confirms beneficiation

ASX Release – 22 May 2008
TEST-WORK CONFIRMS BENEFICIATION FOR YERILLA
PROJECT
• Key Atmospheric Leach milestone achieved with test-work confirming positive nickel beneficiation on a range of material types
• Beneficiation upgrades for nickel range up to 63%
• Over half the resource being siliceous mineralisation responds positively to beneficiation
• Attritioning improves beneficiated nickel recoveries by up to 15%
• Results expand the potential resource utilisation and improve the overall project economics.
Heron Resources Limited (ASX: HRR) (Heron) is pleased to announce beneficiation test-work results of 33 bulk samples
from the Jump-up Dam and Boyce Creek nickel laterite resources has indicated that over 50% of the resource responds positively to beneficiation, resulting in average upgrade values in the order of 40%.
The test-work was carried out by Amdel in Perth, an independent metallurgical testing laboratory.
The test-work results confirm that good beneficiation performance can be achieved from a number of important ore types in the resource. The best beneficiation performance is achieved by the Ferruginous-Nontronite/quartz (FerruginousType 3), Transitional (T) and a portion of the Saprolite-Serpentinite/Quartz (Saprolite Type 2) ore types. The averages of the key ore type results are presented in the table below. The generally positive response of cobalt is pleasing as is the reduction in MgO grades in some beneficiated samples suggesting a potential reduction in acid consuming carbonates through the screening
process.

Heron Managing Director Mathew Longworth said the results were very pleasing and should improve Yerilla’s economics by
leaching higher grade feed, subsequently reducing the volume required for leaching and lowering the volume of reagents for a given production level. He added that cost savings could also be expected.
Mr Longworth said the upgrade percentage was the factor by which the grade of mined ore was increased to determine the
grade of the beneficiated ore available for leaching. For example the Yerilla run-of-mine ore grades around 1% nickel so with an upgrade of 40% would result in a laterite slurry grading 1.4% nickel for leaching.
“These beneficiation results prove to us the merits of the beneficiation process and the benefits it may deliver Yerilla and nickel laterites. We are fortunate to have an ore body which has responded positively to the test-work,” Mr Longworth said.
Beneficiation is a simple low cost concentration step that removes non nickel bearing minerals such as silica from the ore stream, resulting in a lower volume of higher grade mineralisation available for leaching.
“Beneficiation is most profitable on low grade ores and will target over 40 Mt of the resources at Jump-up Dam which are currently sub-grade falling into the 0.5 to 0.75% nickel range. There is now the potential to convert this from resource to reserve,” Mr Longworth said.
The current study is developing a mine schedule to take into account beneficiation and feed this into the process flow sheet design. This study will determine the most profitable beneficiation parameters in terms of grade and recovery.
Nickel leaching test-work for the Atmospheric Leach is progressing well and will be report once results come to hand.
In keeping with Heron’s experience in other projects, some ores do not upgrade as well and maybe more suitable for
leaching without beneficiation. Moderate beneficiation is seen from the Saprolite Type 1 and Saprolite Type 2 ore types, while poor beneficiation is seen from the Ferruginous Type 1 ore type.
Test-work used drum scrubbing attritioning and screening via the batch testing method. Attritioning is a high energy
scrubbing process that improves nickel recoveries on some beneficiated ore types while maintaining the increased grade
available to the leaching circuit. Heron’s test-work indicates attritioning improves nickel recoveries by between 10 and 15% for all ore types.