Australian Tin Resources Pty Ltd

Ardlethan Tin Mine

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Update –30 May 2021

 

ATR is actively progressing its planned Rehabilitation and Tailings Reprocessing Project on the Ardlethan Tin Mine site.


A Development Application (DA),
for a processing plant of up to 150 tonnes per hour capacity was approved by Council in August 2018.

 

Before commencing production, ATR is firstly carrying out small scale pilot plant processing operations on site to prove up the processing technology. Then if the pilot plant results are successful, and following completion and approval of all DA consent conditions, ATR will upsize the plant and commence commercial production.

 

A contract for provision of the pilot plant was awarded to  Mineral Technologies Pty Ltd (a subsidiary of Downer EDI Ltd) in October 2018.  Pilot plant modules were delivered to site in late May 2019 & commissioning of the pilot plant commenced in June 2019.

 

ATR processed about 600 tonnes of tailings in the plant in July 2019 and while the results were promising, the testing highlighted a number of issues that needed addressing.

 

Necessary modifications to the process plant were completed by January 2020.  ATR then carried out further on-site testing. Concentrate samples from these tests were sent to Mineral Technologies’ laboratory in Queensland for assay. The results showed that a considerable percentage of tin was locked in a proportion of sulphides. 

 

In May 2020 Mineral Technologies carried out further off-site testing of the samples collected  in January 2020 using a small flotation cell to remove the sulphides and other contaminants, and a small shaking table to “clean up” the concentrate. This testing demonstrated that production of a concentrate assaying >40% Sn was achieved in the laboratory, and potentially achievable in the field.

 

Following receipt of the above test results, ATR carried out further pilot plant trials to test for grades and recoveries that can be viably achieved under steady state plant operating conditions. .During this round we were able to achieve a grade of >45% Sn, but we could not do so at an acceptable rate of recovery for the process to be commercially viable. 

 

By measuring grades and volumes at various monitoring points in the process circuit we were able to assess where we were “losing” Sn in the waste stream. This was  because the pilot plant screen was not able to successfully separate the target  fine tailings fraction size from the oversize fractions. In order to remedy this problem we experimented unsuccessfully with a number of work-around solutions, until finally in July 2020 we ordered a 5-deck Derrick Screen from USA to replace the single deck screen we had been using. Unfortunately due to Covid 19  restrictions we did not receive the Derrick screen on site until late April 2021. Commissioning  of the newly installed Derrick screen into the process circuit is presently underway and results from various monitoring points show very promising results.

 

We have identified  a number of  actions we expect can further improve Sn grades and recoveries and we will progressively introduce these in a measured step by step manner over the coming months.

 

 

  

 

 

Background

 

The Ardlethan Tin Mine is located approximately 500 km southwest  of Sydney, NSW  5 km NW of Ardlethan township. It covers about 400 hectares on land wholly owned by  EOE (No 75) Pty Ltd (EOE), a wholly owned subsidiary of Australian Tin Resources Pty Ltd (ATR).

 

Excellent road and rail access is available within close proximity to the site. Additionally an approx.50km pipeline from the Murrumbidgie River at Grong Grong  to site is now decommissioned, but subject to approval could potentially be reinstated.

 

ATR acquired EOE in July 2007 with the intention of re-opening the mine site to process approximately 9.0 million tonnes of tin tailings that remained after the previous mining activities. 

 

Mining at Ardlethan commenced in 1912. At first it was on a small scale, but between 1965 and 1986 Aberfoyle Resources NL  mined around 30 million tonnes of granite, initially from open cut operations and later from underground workings.

 

Of the approx 30 million tonnes mined, Aberfoyle processed about 9.0m tonnes of ore assaying 0.46% tin. The remaining  21 million tonnes (approx) had a tin content below Aberfoyle’s cut-off grade of 0.20% tin and were stockpiled in overburden waste dumps which surround the open cuts. In 2020 ATR carried out very successful tests offsite to trial a Tomra Ore Sorter on a bulk sample of our waste rock. The results were impressive with high upgrade rates being achieved and pointed to the feasibility of viably processing the waste rock as a  future option.

 

Mining operations ceased in 1986 due to the collapse of tin prices.

 

Advances in processing methods and increased current tin prices, created the catalyst for ATR to consider recommencing mining operations on site, initially by reprocessing the tailings and possibly also waste material stockpiled at the mine site to produce tin concentrate.

 

Additionally, the underground hard rock resource offers an attractive future opportunity in the longer term.

 

 

Total Resources

Tonnes
(million)

%Sn

Contained Tin

(tonnes)

Tailings *

10.7

0.20%

21,600

Waste Material *

21.3

0.09%

20,200

Hard Rock Underground **

5.5

0.45%

24,700

TOTAL

37.5

 

66,500

 

*     Source: Reynard Australia Pty Ltd Report, October 2011

**  Source: Ardlethan Information Brochure, Molina & Doran, May 1989


Tailings Reprocessing

Retreatment of the tailings from previous mining operations was the main driver for Australian Tin Resources deciding to acquire the Ardlethan tin mine.

 

ATR now has DA approval to construct a 150 tonne per hour plant on site to operate 24 hours/day, 7 days/week.

 

However before moving to production, ATR is firstly carryng out small scale pilot plant processing operations on site to prove up the processing technology. Then if the pilot plant results are successful, and following completion and approval of all DA consent conditions, ATR plans to upsize the processing plant to ~60 tonnes per hour capacity and commence 24/7  production .

 

The plant can be progressively upsized to it’s approved 150 tonnes per hour capacity over time.

 

 

Tailings

JORC Resource

 

Inferred Resources

Indicated Resources

Contained Tin (tonnes)

Tonnes

millions

% Tin

Tonnes

millions

% Tin

Main Tailings Dam

Pre 1964

Post 1964

 

1.94

 

0.30%

 

 

4.87

 

 

0.19%

 

5,800

9,000

Spring Valley Tailings Dam

Pre 1981

Post 1981

 

 

2.67

0.48

 

 

0.17%

0.14%

 

 

 

 

4,500

700

White Crystal Pit Tailings

0.76

0.15%

 

 

1,100

Sulphide Tailings Dam

0.03

1.53%

 

 

500

TOTAL TAILINGS

5.86

0.21%

4.87

0.19%

21,600


   
Source: Reynard Australia Pty Ltd Report, October 2011

 Waste Stockpiles

 

The Ardlethan mine contains approximately 21.3 million tonnes of granite previously mined by Aberfoyle and now stored in waste dumps circling the open cuts. Processing the stockpiled waste material represents a potential option and is a comparatively low capital and operating costs option. Waste material boulders typically range in size from approx 30cm to 100cms in diameter and the waste dumps are readily accessible from existing mine haul roads.

 

ATR has obtained JORC certification of the waste material resources stockpiled at the mine site as summarized in the table below.

 

In 2020 ATR carried out very successful tests offsite to trial a Tomra Ore Sorter on a bulk sample of our waste rock. The results were impressive with high upgrade rates being achieved and pointed to the feasibility of viably processing the waste rock as a  future option.

 

 


Waste Stockpile

JORC Resource

Inferred Resources

Indicated Resources

Contained Tin

(tonnes)

Tonnes

millions

% Tin

Tonnes

millions

% Tin

Main Waste Dump

Pre 1964

Post 1964

 

0.33

18.72

 

0.10%

0.09%

 

 

 

300

17,400

White Crystal

2.20

0.11%

 

 

2,500

TOTAL WASTE

21.25

0.09%

 

 

20,200

Source: Reynard Australia Pty Ltd Report, October 2011

Hard Rock Mining of Underground Resource

The table below summarises the hard rock mineral resources at the time of mine closure in August 1986. These resources consist of broken ore in stopes, remnants, pillars and resources inferred from drilling. Access would be via a decline just north of the main Ardwest / Wild Cherry Open Cut.

 

There is further potential deeper underground on the mine site and in surrounding environs. There are also some small deposits of known high grade ore at or near the surface.

 

Hard Rock Underground Resource

 

Inferred Resources

Indicated Resources

Contained Tin (tonnes)

Tonnes

millions

% Tin

Tonnes

millions

% Tin

Measured

 

 

.05

0.51%

275

Indicated

 

 

.80

0.50%

3,980

Inferred

0.47

0.36%

 

 

1,670

Potential

 - Black Reef /Champion

 - Godfrey

 - Keogh East

 

0.28

3.80

0.10

 

0.83%

0.42%

0.50%

 

 

 

2,325

15,950

500

TOTAL HARD ROCK

4.64

0.44%

0.85

0.50%

24,700

 

  Source - Ardlethan Information Brochure, Molina & Doran, May 1989.

 

 

 

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