High Grade Zinc Sulfate Monohydrate Production

TORONTO - Nevada Zinc Corporation reported the production of bench scale high-grade zinc sulfate monohydrate. The sample was produced from the multiphase pilot plant program being conducted by Hazen Research, Inc. ("Hazen") for the Company's Lone Mountain zinc project. Hazen completed bench scale crystallization work to recover zinc sulfate from purified pregnant leach solution ("PLS"). Evaporation was carried out at 60°C using a rotary evaporator. Approximately 60% of the purified PLS mass was evaporated from the solution, crystallizing a mixture of zinc sulfate heptahydrate and zinc sulfate monohydrate. The crystallized product was dehydrated to zinc sulfate monohydrate at 80°C.

The dehydrated zinc sulfate product was identified by x-ray diffraction (XRD) as zinc sulfate monohydrate, with no other phases detected. The product has assayed 97%-99% zinc sulfate monohydrate by titration. The sample was assayed at 37.6% Zn by inductively coupled plasma optical emission spectroscopy ("ICP-OES") and 18.7% total sulfur by combustion (LECO). Ca and Mg assayed 0.01% and 0.03%, respectively. ICP-OES analyses of relevant impurities (As, Cd, Co, Pb, Mo, Co, Ni) were below the reported detection limit for each element (<50 ppm). Additional analyses of impurities are in progress to better define at lower detection limits. While zinc content in commercial zinc sulfate products can vary due to product specifications and applications, the typical zinc grade in zinc sulfate monohydrate is 35.5% Zn.

Max Vichniakov, President and CEO, said, "We are extremely pleased with the zinc sulfate sample produced, one of the key objectives of our multiphase pilot program. The ability to produce a commercial grade zinc sulfate monohydrate from the representative mineralized material (bulk sample) from the Lone Mountain site was one of our primary goals. The conceptual technological approach was always there, but it's about turning it into a product. We arrived at this critical milestone by virtue of extensive test work and numerous hydrometallurgical experiments with an objective of designing a sustainable and environmentally friendly process to make a naturally produced, traceable to the source, high-grade zinc sulfate product."

A bulk operation to produce approximately 150 lbs. of a commercial grade zinc sulfate monohydrate product and economic assessment of the production process including capital costs are the next and final phases of the Company's multiphase pilot plant program projected to be completed in Q4/21. The Company will provide updates as material results become available.