@Bayhunter, in regard to your concerns as per post # 65480433,...

@Bayhunter, in regard to your concerns as per post # 65480433, You stated,

“The copper in the existing heap leach was not included in the Jorc resource and I am most nervous about the true copper content of these retreat stacks. How can they accurately state there is 0.53% copper content on average over the retreat pads???? i am guessing the remaining copper in these stacks will be quite variable.”

Apparently, the existing stacked leach pads have significant amount of copper in them because the previous operator/s did not understand leaching and Bazza says he knows better. i believe this point may have been difficult for Bazz to convince the lenders, but it seems he has done it.

I briefly responded to @DDBB back in March about the same subject but let’s go into further detail. I found this detail from several sites in relation to the air core drilling of the existing Heap Leach stacks,

Air core drilling is a superior first pass drilling technique as, opposed to RAB, the sample contamination is minimised through the dual tube system.

· Air Core drilling uses both a compressor and blade type bits to bore through the ground while raising the soil sample to the surface at the same time.

· Air Core drilling utilises high-pressure air and dual walled rods to penetrate the ground and return the sample to the surface through the inner tube and then through a sampling system. The ground is cut through with the use of a steel blade type bit. This sample is then collected and analysed.

• Air Core cannot drill to the depths of Reverse Circulation rigs.

• Air Core rigs are lightweight and much quicker to pack and move around. Due to the smaller footprint, they have less environmental impact.

• Reverse Circulation drill rigs use larger size drill rods and drill bits.

• Air Core drilling does not require hole casing.

• Air Core drilling cuts through the ground formation where Reverse Circulation smashes through it using percussion.

What Is Air Core Drilling?

An introduction to the benefits of Air Core drilling

What is air core drilling? Air core drilling uses three-bladed steel or tungsten drill bits to bore holes into unconsolidated ground and is used when safe and clean removal of sample material is paramount.

Things we’re covering in this article:

• How does air core work?

• Where is air core drilling applied?

• The advantages of air core drilling

• The disadvantages of air core drilling

• The importance of good quality air core drilling bits

• What’s the difference between air core drill and RC drilling?

Air core drilling is an inexpensive method of exploration drilling that can be employed when safe removal of sample material is paramount. Where possible, it is preferred over RAB (Percussion rotary air blast drilling) drilling and unlike the diamond drilling method, which withdraws a small diameter core of rock from the orebody, air core drilling is much faster and more cost-effective.

As the name suggests, air core drilling relies on compressed air to flush cutting samples out of your drill holes. This enables the safer collection of samples without unnecessary damage to the surrounding area and results in a more effective analysis sample.

Where is Air Core Drilling Applied?

Air core drilling is a valuable method of drilling for organisations looking to reduce the risk of sample cross-contamination. It’s commonly used in first-pass exploration drill programs on unconsolidated ground, with an optimal depth of up to 300 metres.

Advantages of Air Core Drilling

Air core drilling has clear advantages over other drilling methods.

1. It eliminates the need for casting holes.

2. It provides a more representative sample of material. The nature of the expulsion of the materials provides samples that are easier to analyse.

3. Delivers safer sample removal. Due to its reliance on compressed air injection, air core drilling involves less damage to the samples, when compared with blast drilling.

4. Boosts efficiencies and reduces costs. Air core drilling is an efficient method for removing material. It enables real-time sample collection, which speeds up drilling rates, resulting in reduced field costs. Air core drill rigs are also lighter in weight than other rigs, meaning they’re quicker and easier to transport.

5. Less chance of cross-contamination. As compressed air is used to flush the cuttings through the inner tube, there is less sample pollution than other methods.

Disadvantages of Air Core Drilling

While there are many advantages to air core drilling, it also comes with disadvantages when compared to other methods of drilling.

1. Air core drilling can be slower. While air core drilling is considered more efficient, the drills typically operate at a slower speed than other methods, making the drill process itself slower.

2. Depth limited. Depending on a number of variables but predominantly available air pressure, air core drilling is usually limited to depths of 50-120m.

3. Fresh rock penetration limited. While air core drilling is able to drill through cap rock at the top of a hole using a hammer or tri-cone roller, air core drilling is usually unable to penetrate fresh rock.

The Importance of Good Quality Air Core Drilling Bits

Good quality air core drilling bits are invaluable, and can make all the difference in your drilling program.

The better-quality your drill bit, the better your results. A good quality drill bit will use better materials in its manufacturing process, making it stronger, and more able to hold up to stress (such as drilling through quartz). They’re built for reliability and versatility, with improved shock resistance built into the blade and shell design.

Poor quality air core drill bits aren’t as efficient, so they take longer to complete your drilling. They’re more likely to break, and ultimately end up wasting your time, and costing more money. With a poor-quality drill bit, you run the risk of material blocking your drill and inner tubes, particularly in thick, clay-like earth.

What’s The Difference Between Air Core Drilling and RC Drilling?

While the equipment used in air core drilling and RC drilling is similar, the mechanisms involved are different, so each is useful in different situations.

Both involve the use of compressed air to flush out samples. However, air core drilling is ideal where unconsolidated ground is present.

RC drilling on the other hand, uses the added element of concussive force to power the drill bit, pulverising the rock in its path. This makes RC drilling ideal for harder ground. RC drilling is also typically able to achieve greater depths, and better-quality samples, than other types of drilling.

So the aircore drilling is best practice to see what is actually within the leach pads. CYM also trench tested the heterogenous pads as well.

The existing heaps came from the Nifty oxide resource that has been drilled and measured using JORC codes & revisions which all mining entities on the asx follow. JORC 1989, 1992, 1996, 1999, 2004 and now 2012.

Restart Study states, “The project NPV and favourable economic outcome considers and includes re-treatment of and copper production from the historical heap leach material, however the 2012 JORC Code is unable to be applied to accommodate the existing historical heap leach material in terms of Mineral Resource classification. The tonnes and grade of the material is based on historical production reconciliation as a heap leach quantity ought to be, that is a stockpile of material less the physical metal extracted thereof.”

From 6/12/21 ann: In addition, there are 550 sonic samples yet to be assayed that have been obtained from around the site to test for the location of stockpiled oxide material. A consultant has been engaged to firstly, build a complete mass balance and copper recovery cathode software model for the project based on the metallurgical parameters and then secondly, to design and build a metallurgical accounting system for the project so that it is ready upon the commencement of plating copper metal at Nifty. This work is well advanced.

From The Market Herald article 6/7/21;

A sonic drill rig was mobilised to the site to collect core samples for metallurgical testwork. According to the company, the rig has been very effective in producing complete samples from the existing heap leach pads.

I'd say CYM have a very good idea what is contained in the existing HL pads which were expanded upon in the Restart Study.