Post: Comparative Assessment of Selected Cyanide Alternatives for Gold Extraction...

New comparative assessment argues the company may offer something rare in gold processing: a non-cyanide route with near-cyanide chemistry cost and a more direct path to recovery.

In gold metallurgy, plenty of alternative reagents can dissolve gold. Far fewer can do it in a way that still looks commercially workable once the slurry leaves the leach tank.

That is the central takeaway from a new comparative assessment reviewing RZOLV against a slate of alternative gold-leach routes for concentrate treatment. The report does not frame the contest as a narrow chemistry debate. Instead, it asks the question mining companies and engineers ultimately care about: which process still makes sense after filtration, liquor handling, downstream recovery, recycle, and implementation burden are taken into account?

On that basis, the management led 200 page study concludes that the field separates quickly. Some routes may show technically valid dissolution behavior, but become more specialized, more chemically demanding, or significantly more expensive once judged as full process systems. RZOLV, by contrast, is presented as occupying a notably different position: a non-cyanide method that appears to preserve a relatively direct aqueous leach-filter-recovery pathway while remaining in the same broad indicative chemistry-cost range as conventional sodium cyanide.

That is a potentially important claim in a sector still searching for a realistic cyanide alternative.

A different way to compare gold leach routes

The report compares eight methods on a common screening basis: agitated tank leaching of gold concentrate, pressure filtration, cake washing or mother-liquor displacement, and downstream recovery based on the liquid phase actually produced after filtration. That distinction matters. In practice, a leach reagent is not judged solely by whether it dissolves gold, but by whether the resulting filtrate can move efficiently and credibly into recovery.

The methods reviewed include RZOLV, a sodium cyanide benchmark, sodium cyanide plus glycine, ammoniacal thiosulfate, chloride-bromide, acidic bromide-oxidant, iodide-iodate, and a DMSO solvent route. The study groups them into four classes: direct aqueous methods, recovery-specialized aqueous methods, reactive halide methods, and nonaqueous solvent methods.

That framework is where the report becomes especially bullish on RZOLV. It argues that RZOLV is the only non-cyanide method in the comparison that still stays within the most commercially intelligible class: a relatively direct aqueous recovery architecture. In plain English, that means it appears to preserve the shorter, cleaner path from dissolution to recovered metal that operators already understand, without remaining trapped inside a cyanide-centered process.

Near-cyanide cost without a cyanide-centered circuit

One of the more eye-catching parts of the assessment is the chemistry-cost comparison.

On the selected basis used in the report, RZOLV is modeled at approximately US$23.03 per tonne of concentrate, versus US$23.29 for the sodium cyanide benchmark. Sodium cyanide plus glycine is estimated at roughly US$31.81 to US$34.65 per tonne, chloride-bromide at US$80.74, acidic bromide-oxidant at US$320.41, iodide-iodate at US$4,382 to US$4,691, and the DMSO solvent route at US$4,484 to US$4,779 per tonne. Thiosulfate is shown as potentially attractive on direct reagent charge under favorable assumptions, but with economics that remain highly sensitive to consumption, solution control, and downstream recovery burden.

Those figures are expressly presented as indicative screening estimates rather than feasibility-level economics, but they still frame the commercial challenge facing most non-cyanide competitors. Many alternative systems can be made to sound compelling at the reagent level, yet start to lose ground when full process burden is considered. The report’s core argument is that RZOLV appears to avoid that trap more effectively than the other alternatives reviewed.

Why post-filtration recovery may be the real battleground

The strongest part of the assessment may be its insistence that not all dissolved-gold solutions are equal.

RZOLV and sodium cyanide are described as “direct aqueous” methods because the filtrate is treated, in principle, as an aqueous pregnant leach solution that can move toward downstream recovery without a major conversion step. Sodium cyanide plus glycine remains broadly in that camp too, but the report says it should still be viewed as a modified cyanide circuit, not a genuine architectural departure from cyanide.

Thiosulfate, while aqueous, is portrayed as less direct because the pregnant liquor generally requires more specialized downstream recovery. The halide systems are treated as a separate class altogether, producing reactive liquors that impose heavier burdens in containment, wash sensitivity, materials selection, and downstream compatibility. The DMSO route is presented as the most structurally indirect of all, requiring precipitation, secondary separation, solvent recovery, and regeneration before recycle can even be established.

That distinction goes to the heart of commercial adoption. A process may perform well in a dissolution test, but if the liquid phase it produces is harder to preserve, harder to wash, harder to recover from, or harder to control at scale, the practical advantage can erode quickly. The report argues that this is exactly where many alternative leach routes become less compelling — and where RZOLV begins to stand out.

“The most attractive method is not merely the one that dissolves gold, but the one that carries the lowest overall burden through the full recovery pathway.” - Duane Nelson

More than a green story

The report also pushes RZOLV beyond the usual “non-cyanide” narrative.

Its commercial significance, the study suggests, is not simply that it avoids cyanide. The bigger point is that it appears to combine non-cyanide positioning with a process logic that still looks understandable to conventional hydrometallurgical operators. That matters because many alternative lixiviants have struggled to gain traction not because they are scientifically invalid, but because they impose too much downstream complexity, too much specialty chemistry burden, or too much cost.

The assessment also addresses toxicity, handling, and control burden at a screening level. It notes that sodium cyanide remains the high-burden benchmark because of its cyanide-centered solution management, detoxification requirements, containment sensitivity, and incident exposure profile. RZOLV is differentiated by its non-cyanide position and by early evidence indicating a more favorable practical toxicity profile than cyanide-based systems, while still requiring normal chemical handling discipline and method-specific safety review.

For miners, that combination could be meaningful. The industry’s problem has never been finding theoretical alternatives to cyanide. It has been finding one that can check enough boxes at once: technical credibility, downstream recoverability, manageable cost, operational intelligibility, and a stronger environmental or permitting profile. The report’s thesis is that RZOLV may be one of the few systems now pushing into that territory.

Still, in a sector where many non-cyanide ideas remain either too expensive, too specialized, or too indirect, this assessment delivers a clear message: RZOLV may no longer belong in the category of interesting alternative chemistry. It may now belong in the category of serious commercial contender.

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Disclaimer

This article has been prepared for general informational purposes only and summarizes selected conclusions from a screening-level comparative assessment prepared by RZOLV under a defined set of assumptions and a common comparison basis. The article does not constitute a feasibility study, preliminary economic assessment, NI 43-101 technical report, mineral resource or reserve estimate, engineering study, process guarantee, or formal economic analysis. The comparative statements, indicative chemistry-cost references, technical observations, and commercial interpretations presented herein are illustrative only, are based on representative methods reviewed under specific assumptions, and are not intended to represent definitive or universally applicable conclusions across all ore types, concentrate types, tailings, residues, or operating environments. Actual technical and economic performance may vary materially depending on mineralogy, feed characteristics, impurity profile, particle size distribution, oxidation state, reagent consumption, recycle efficiency, downstream recovery response, engineering design, operating conditions, environmental requirements, regulatory considerations, and other project-specific factors. The article should not be relied upon as the basis for project selection, process implementation, investment decisions, or any other commercial determination without independent technical, legal, and financial review. Statements regarding the potential advantages, positioning, scalability, validation pathway, commercial applicability, or future prospects of RZOLV or any other method may constitute forward-looking information within the meaning of applicable securities laws. Forward-looking information is based on management’s current expectations, estimates, assumptions, and beliefs, and is subject to known and unknown risks, uncertainties, and other factors that may cause actual results or outcomes to differ materially from those expressed or implied by such forward-looking information. Readers are cautioned not to place undue reliance on forward-looking information.