LeachWELLTM 60X is the new standard in gold assaying

In gold mining, time is money. Every hour waiting on assay results delays exploration, resource estimates, and mine planning. For decades, the bottle roll assay has been the industry’s workhorse for determining recoverable gold—vital for feasibility studies and grade control. But it has always been constrained by one problem: time.

A standard bottle roll test, based on the Elsner equation for gold dissolution, usually requires 24–48 hours to reach maximum extraction. This lag creates a bottleneck across the mining cycle, from early exploration through to operational decision-making.

That bottleneck is now obsolete. Mineral Process Control (MPC) Pty Ltd has redefined assay practice with LeachWELL^TM 60X—a proprietary accelerant that doesn’t just speed up bottle rolls, it transforms them.

The Bottleneck: Time and Variability

Bottle roll assays simulate full-scale leaching to predict potential recovery of gold and silver. They inform plant design, economics, and resource reporting. But confidence has always meant waiting until the leaching curve flattens. Stopping early risks underestimating recoveries; waiting too long wastes valuable lab time.

Ore variability complicates this further. With nuggety gold, large samples—500 g to 2 kg—are required to ensure representativity. This makes time and consistency even more critical.

LeachWELL^TM 60X resolves both problems at once.

The Solution: LeachWELL^TM 60X’s Transformative Kinetics

LeachWELL^TM 60X is more than an additive—it’s a catalytic accelerator that changes the kinetics of cyanidation.

The Dual Advantage:

1. Speed: It accelerates the dissolution of gold and silver by up to 60 times. Tests that once took 48 hours now achieve maximum recovery in just 1–2 hours. This reduction in turnaround time is the single greatest efficiency gain available to labs.
2. Consistency and Cyanide Efficiency: The formula suppresses cyanide losses to competing reactions (e.g. sulphides), preserving free cyanide for gold dissolution. The result: higher recoveries, greater repeatability, and confidence that results are both reliable and fast.

It’s no surprise that “LeachWELL assay” is now often used interchangeably with “bottle roll” in exploration reports and corporate disclosures worldwide.

Safer, Smarter Assaying: The Role of AssayTabs

To ensure consistency and safety in the lab, MPC has developed AssayTabs^TM—a simple, pre-measured tablet that combines LeachWELL^TM 60X with sodium cyanide. Instead of handling powders or liquids, operators can now drop a tablet directly into the bottle roll.

This innovation delivers three critical benefits:

• Safety: Eliminates manual handling of cyanide powders and reduces operator exposure.
• Accuracy: Each tab contains the precise reagent dose required for a standard bottle roll, ensuring consistent results across batches.
• Efficiency: Simplifies preparation, standardizes workflow, and ensures laboratories adopt best-practice methodology with minimal training.

AssayTabs are now regarded as the safest and most effective way to apply LeachWELL^TM in routine bottle roll assays, making high-speed, high-precision testing both accessible and sustainable.

Real-World Impact: Proof in the Field

The transition from traditional fire assays and slow bottle rolls to LeachWELL^TM methods—particularly with AssayTabs—has delivered tangible benefits across projects worldwide.

Case Study 1: Unlocking Value in West Africa

A gold explorer in Mali re-analysed drilling samples using a 2 kg LeachWELL^TM bottle roll with residue fire assay, comparing it to a 50 g fire assay.

• Fire Assay Result: 5 m @ 3.75 g/t Au from 84 m
• LeachWELL^TM Result: 5 m @ 6.14 g/t Au from 84 m

The larger, faster LeachWELL^TM sample captured coarse free gold missed by fire assay, boosting recovery by 150%. This directly increased the reported resource base and improved project economics.

Case Study 2: Precision Grade Control in British Columbia

A Canadian project adopted a 1,000 g LeachWELL^TM bottle roll with AssayTabs for grade control in a high-grade starter pit. Results included:

• High Repeatability – confirming mineralization continuity
• High Recovery – 96.5% gold and 69.3% silver

The speed, safety, and precision enabled better grade selectivity, lower dilution, and tighter mine scheduling—essential for the project’s early production phase.

The Benchmark for Modern Assay Practice

LeachWELL^TM 60X, delivered via AssayTabs^TM, allows labs to test larger, more representative samples (up to 2 kg) with unprecedented speed, accuracy, and safety. Whether refining exploration targets or setting daily plant throughput, mining decisions can now be based on the most reliable and timely data possible.

When project viability hinges on rapid, accurate recoverable metal data, there is only one choice: LeachWELL^TM 60X with AssayTabs.

The future of bottle roll assaying is here.

Contact Mineral Process Control (MPC) Pty Ltd today to optimize your lab efficiency and accelerate your path to discovery.