Progress Update On The Multiphase Pilot Plant Program At The Lone Mountain Site

TORONTO – Nevada Zinc Corporation reported on the progress of the multiphase pilot plant program to produce zinc sulfate monohydrate at Lone Mountain zinc project. It has completed bench-scale tests on the representative mineralized material (bulk sample) from the Lone Mountain site resulting in the successful completion of gravity separation tests to concentrate zinc, separation of gangue (waste) minerals dolomite and calcite, and successful acid leaching tests. Based on filtrate assays, the leaching test showed recovery of 86% zinc from the neutralized leach, decreased soluble silica to 0.01% and precipitated aluminum and iron, which are deleterious elements for the envisioned process flowsheet.

The separation of zinc from zinc-bearing oxide ores is known for its metallurgical challenges in the zinc mining industry as zinc oxide ores may be composed of several zinc-bearing minerals. Additionally, soluble silicon dioxide in the oxide ore can cause the formation of silica gel in the solution which can negatively impact the acid leaching process. Having successfully addressed these challenges is a critical achievement by the Company for the development of the Nevada Zinc’s Lone Mountain zinc project.

To date, extensive research and studies and performed several heavy liquid separation, gravity separation, flotation, and leaching experiments on the zinc-bearing minerals of hemimorphite and smithsonite. Gravity separation experiments vigorously tested different scenarios of concentrate preparation and refined the envisioned process flowsheet. Zinc concentration tests via gravity separation methods were followed by acid leaching tests to further validate and optimize the potential process flowsheet for cost-effective zinc sulfate monohydrate production.

Max Vichniakov, President and CEO, said, “We are extremely pleased with the positive results to-date from our bench-scale testing program. Achieving 86% zinc recoveries in acid leaching tests, combined with a significant reduction of silica will be a direct cost benefit for the zinc sulfate production process. The currently envisioned process flowsheet will also eliminate the necessity for direct flotation, which is common in the conventional production of zinc concentrate and metal. This could not only lower the process’ capital costs, it will also result in a more environmentally sustainable operation as fewer chemical reagents will be required. We hope these very promising results to-date will lead to a robust process flowsheet with low overall capital and operating costs. Looking ahead, we are excited about the prospect of designing a unique, proprietary, cost-competitive, and most importantly environmentally sustainable zinc sulfate production process tailored to our Lone Mountain mineralization.”

The next phase of the bench-scale testing program to produce zinc sulfate monohydrate has now commenced and the Company will provide updates as material results become available. While the program experienced some delays due to required process optimization test work, follow-up tests, and further technical studies, the program remains on track and the Company expects the program to be completed by the end of the third quarter of 2021.