Flotation Concentrates

Technical and Economic Limitations of Sending Sulfide Concentrates to Smelters

Gold-bearing sulfide flotation concentrates typically contain high levels of pyrite, pyrrhotite, chalcopyrite, arsenopyrite, and associated base metals. When shipped to smelters, these concentrates incur substantial penalties due to arsenic, antimony, sulfur content, moisture, and impurity profiles. Smelters apply treatment charges (TCs), refining charges (RCs), and penalty schedules that can remove 10–30% of contained value, and concentrate shipments are often subject to long logistical timelines, assay disputes, moisture loss, and payability caps (typically 85–95% depending on the smelter). Metallurgically, smelters rely on oxidative roasting and high-temperature blister/furnace reactions that destroy gold inclusions but produce off-gases rich in SO₂, As₂O₃, and other hazardous emissions—requiring strict environmental compliance and limiting the number of smelters willing to accept high-impurity material. As concentrate arsenic levels increase, smelter acceptance decreases sharply, leading to surcharges or outright rejection. In short, conventional smelting imposes heavy economic leakage, environmental constraints, and dependency on third-party processors that mining operators increasingly view as unsustainable.

RZOLV™ as a Clean, On-Site Hydrometallurgical Alternative to Smelting

RZOLV™ enables direct on-site solubilization of gold from sulfide concentrates under controlled acidic pH (1.2–2.6) and moderate ORP conditions, eliminating the need for high-temperature processing entirely. Unlike cyanide—which performs poorly on high-sulfide, high-arsenic concentrates due to rapid consumption from sulfur oxidation, thiocyanate formation, and passivation—RZOLV™ maintains stable dissolution kinetics even in concentrates containing high levels of pyrite, arsenopyrite, and base-metal sulfides. Sulfur and arsenic intermediates do not form parasitic complexes that destroy the reagent, and ferric/ferrous cycling remains compatible with the leach mechanism. RZOLV™ allows concentrates to be leached directly, producing high-grade pregnant solution that can be treated via standard carbon adsorption or ion-exchange systems, leaving behind a low-toxicity, de-sulfidized solid residue. Electrochemical regeneration maintains reagent potency, keeping operating costs well below smelter deductions. Operators avoid TCRC penalties, moisture losses, shipping delays, emissions risks, and environmental liabilities. The result is a clean, low-temperature, closed-loop hydrometallurgical flowsheet that converts concentrates to gold on site with higher payable metal, lower unit cost, and no smelter dependency.

Using RZOLV™ to leach sulfide flotation concentrates on-site provides:
 

• Higher gold payability - assay variance, etc.

• No smelter penalties for arsenic, sulfur, antimony, or deleterious metals

• Dramatically lower operating costs (no TCs/RCs/shipping)

• Zero SO₂/As₂O₃ emissions

• High recoveries even on complex arsenopyrite-rich concentrates

• Rapid cash flow due to immediate on-site settlement

• Full operational control with no reliance on smelter capacity or acceptance

RZOLV™ effectively turns a traditionally penalized, transported product into an on-site, high-value hydrometallurgical feedstock.
Innovation Mining’s proprietary RZOLV™ non-cyanide lixiviant provides a cost-effective and environmentally superior alternative to conventional smelting. As a water-based reagent, RZOLV™ is engineered to selectively dissolve gold from gravity concentrates under ambient conditions, achieving high recoveries without the need for high-temperature furnaces or hazardous cyanide handling. This approach not only lowers operating costs but also eliminates the financial and logistical burden of offshore smelter reliance.

By replacing smelters with regional or site-based RZOLV™ processing facilities, miners can directly recover gold into doré, capturing a greater share of the value chain. Processing concentrates locally also reduces exposure to shipment risks and accelerates cash flow, while residues generated by RZOLV™ treatment are far cleaner and easier to manage than arsenic-rich smelter slags.

The adoption of RZOLV™ represents a transformative step for the gold industry, modernizing the concentrate monetization pathway. Instead of surrendering margin to smelters, miners can apply a proven, non-cyanide technology that delivers high recoveries, improves environmental outcomes, and ensures that the full economic potential of their gravity concentrates is realized.