Successful Test-Work Continues at Mt Gunson Copper Project
Perth, Jan 29, 2015 AEST (ABN Newswire) - Strandline Resources Limited (
ASX:STA) provides an update on Pre-Feasibility Studies being conducted into the mining and processing of its MG14 and Windabout copper-cobalt-silver resources ("the Mining Projects") in South Australia.
Highlights
- Metallurgical studies significantly de-risk Mt Gunson copper production project
- Game-changing 'Proof of Concept' metallurgical test-work (using conventional technology) indicate:
- Copper recoveries of up to 90% are achievable
- High value cobalt recoveries of + 80% are achievable
- Improved metallurgical results have potential to vastly improve potential economics
- Combined Indicated Resources total +200,000 tonnes contained copper
- Pre-Feasibility Studies continuing at no cost to Strandline with planned completion by mid-year
- Bankable Feasibility Study completion targeted by mid-2016
The Mining Projects are contained within Strandline's 100% owned Mt Gunson Copper Project, a large (825km2) tenement package (Table 3) centrally located in the world-class Olympic Dam copper-gold province and situated 130km north of Port Augusta, with roads and power to site (see Figures 1 & 2 in link below).
Mt Gunson is the third-largest copper producing district in South Australia, with historical production estimated at over 170,000 tonnes. The Windabout and MG14 deposits are shallow, flat-lying black-shale hosted copper-cobalt-silver sulphide deposits with a combined Indicated Resource estimate totalling 20.3 million tonnes averaging 1.03% copper, 0.05% cobalt and 10.32 g/t silver for 210,000t contained copper (Tables 1 & 2 in link below).
Originally, the Mining Projects were considered challenging because earlier conventional sulphide flotation tests resulted in a copper recovery range of only 54% to 68%. Recent metallurgical test-work by joint venture partner Torrens Mining Limited ("Torrens"), which included sodium cyanide leach tests, demonstrated copper recoveries of 80% to 85%, with an upside of 90+% copper and sodium cyanide regeneration greater than 80%.
Metallurgical Test-work Update
As part of a Pre-Feasibility being funded by Torrens Mining Limited ("Torrens") (see ASX announcement dated 11 December 2013), a series of bench-top metallurgical tests to examine the viability of sodium cyanide leaching of the copper in these deposits have been completed.
Successful preliminary test-work completed in the first half of 2014 was followed up with more detailed test-work which was completed in the December Quarter 2014. This program included sodium cyanide leach tests, leach-tailings flotation and sodium cyanide regeneration tests on 55 available Windabout drill samples.
The results demonstrated that, while variable, about 70 to 75% of the copper in the Windabout deposit and 85 to 90% of that in the MG14 deposit was readily leached by cyanide into solution.
In addition, a preliminary program of float test-work on the residues from the leach has shown that a significant proportion of the remaining copper can be floated into a concentrate.
This is a critical development for the potential economics of the development of the deposits, as overall copper recoveries of more than 90% may be achievable by the combined leach-float process.
The copper recoveries represent a dramatic improvement from previous test-work which applied a conventional sulphide flotation test and achieved recoveries of 54% to 68%.
These tests also showed more than 80% of the cobalt and 50% of the silver reporting into this concentrate. Significantly, cobalt is currently about twice the value of nickel and five times the value of copper so this will also have a potentially positive impact on project economics.
The test-work also demonstrated that copper is readily precipitated from the pregnant leach solution as potentially saleable chalcocite (copper sulphide Cu2S) and that sodium cyanide regeneration, a key cost driver of the cyanide leach process, could be achieved at a level in excess of 80% by the CSIRO-developed SART (Sulphidisation, Acidification, Recovery, Thickening) process which is in commercial use at a number of mining operations.
Torrens can earn a 51% interest in the Mining Projects by undertaking, at its sole cost (up to $2.5M), all tests and studies necessary to determine the viability of a mining and processing operation at Mt Gunson, and deliver a Bankable Feasibility Study by mid-2016.
Torrens is expecting to complete its Pre-Feasibility Studies over the coming months with a seamless transition into a Bankable Feasibility Study by mid-year.
Appointment of Study Manager
Mining engineering and metallurgical specialist, Mining & Process Solutions Pty Ltd was recently appointed as Study Manager to advise Torrens on metallurgical issues and be responsible for the completion and independent reporting of the Mt Gunson feasibility studies, through to completion of a Bankable Feasibility Study.
Upcoming Scope of Works
The upcoming scope of feasibility works at the Project for the first half of 2015 includes:
- Mineral Resources - Drilling campaign planned to provide more samples to complete metallurgical test-work and assist with JORC 2012 mineral resource updates and preliminary planning of the mining operations.
- Metallurgy - Ongoing leaching, flotation and hydro-classification test-work to refine and optimise the mineral processing flowsheet.
- Mining Studies - mine design for the Windabout pit by independent mining engineers familiar with the use of Bucketwheel Excavator mining systems. The engineers will produce more accurate data on mine operational and capital costs. The engineers will also undertake 3D modelling of the mineral deposits, including geostatistical analyses to metallurgical metal recovery data with exploration grade analytical data.
- Approvals and Licenses - commencement of the mining approvals process with the South Australian Department of State Development.
About MG14 and Windabout Mineral Resources
The MG14 Resource has a footprint of 1000m by 250m below about 25m of cover. Discovered in 1973, the deposit has been tested by a total of 117 drill holes and remains open to the north-west.
A JORC 2012 compliant Mineral Resource was estimated by T. Callaghan in June 2013, with a Cut-off Grade of 0.5% Cu and an average SG of 2.5. (see ASX announcement 6 June 2013):
The Windabout deposit, located about 6km north of MG14 and is approximately 2km by 1km in area. The deposit is also flat-lying at about 70m below surface. Also discovered about 1973, the deposit has been extensively tested by 195 drill holes.
The larger Windabout deposit has a pre-2000 JORC Indicated Resource estimate1 of 18.7 million tonnes averaging 1% copper, 500 ppm cobalt and 10 g/t silver at 0.5% copper cut off.
Regional Exploration Upside
Outside the Excised Areas containing the Windabout and MG14 deposits (Figure 2 in link below), Strandline's 100% owned Mt Gunson exploration ground (Table 3 in link below) has previously been the subject of joint venture exploration with several major mining groups. This work generated a number of high priority copper-gold and copper-cobalt-silver targets requiring further drill testing.
Much of the exploration focus in recent years has been on the search for Olympic Dam-style mineralisation with BHP Billiton's world class copper-gold-uranium mine only 100kms to the north. During this work, Strandline's 100% owned Emmie Bluff copper-cobalt-silver resource was discovered while drilling through the Cover Sequence. With a pre-2000 JORC Inferred Resource estimate2 of 24Mt averaging 1.3% Cu, 600ppm Co and 10g/t Ag, Emmie Bluff is similar in size, shape and composition to Windabout. However, it is located at approximately 450m depth from surface and could be a source of additional resource if Windabout and MG14 can be brought to production.
The Company is currently compiling all exploration data with a view to determine its next steps to test these potentially very large targets within the Olympic Dam copper-gold province.
To view tables and figures, please visit:
http://media.abnnewswire.net/media/en/docs/ASX-STA-707642.pdf
About Strandline Resources Limited
Strandline Resources is an Australian Stock Exchange listed company (ASX:STA) (OTCMKTS:STQNF) is a Tanzanian-focused mineral sands developer positioned within the world’s major zircon and titanium producing corridor in South East Africa. Strandline has a dominant mineral sands position with a series of 100% owned projects spread along 350km of the Tanzanian coastline.
Strandline’s strategy is to develop and operate quality, low cost, expandable mining assets with market differentiation. Leveraging off the exploration success of 2016, the Company’s focus is to continue its aggressive exploration and development strategy to progress economically attractive projects based on high unit value titanium and zircon products.
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