Australian-based lithium-boron mine developer Global Geoscience Ltd has announced the results of the first phase of the PFS for the 100%-owned Rhyolite Ridge lithium-boron project in Nevada, USA.

The critical trade-off studies demonstrate a clear path forward for the project, and highlight the potential for Rhyolite Ridge to be a major, low-cost producer of lithium and boron in an environmentally sustainable manner that uses self-generated, zero-carbon power and minimises both water useage and surface disturbance.

• Vat leaching process and an on-site acid plant selected – yielding more operational and economic benefits for emerging Rhyolite Ridge lithium-boron mine in Nevada
• Rhyolite Ridge is the global front-runner to become the first mine to recover lithium using the proven and well understood vat leaching method
• Sulphuric acid cost estimated at $20-$30/t after credit from steam and power generation – an important economic driver for the lithium-boron project
• PFS on track for release in Q3 2018.

Global Geoscience’s Managing Director, Bernard Rowe commented:  “Sulphuric acid is an important economic driver for the project, and the combination of vat leaching together with an on-site acid plant will substantially lower the cost of acid, thus reducing the overall operating costs.

“An acid plant will produce large amounts of steam that can be used for heating in the processing plant and for generation of electricity via steam-driven turbines with excess power available for selling into the grid.

“Steam produced from the acid plant negates the high input costs normally associated with mechanical evaporation.

“Vat leaching, coupled with mechanical evaporation, produces the most concentrated pregnant leach solution with consistent composition, thus simplifying downstream processing.

“With the critical trade-off analysis completed, the PFS is on track to be completed in mid-2018 with the outcomes scheduled to be released in Q3 2018.”

Four critical trade-off studies were completed as Phase 1 of the PFS. Vat Leaching has been selected as the leaching method providing:

• A more controlled leach environment with higher concentrations of lithium and boron into the pregnant leach solution (PLS)
• Less evaporation of the PLS is required because of the higher initial concentrations, resulting in fewer mechanical evaporators and lower power consumption
• Materially lower capital and operating costs compared to alternative leaching techniques.

An on-site acid plant has been selected as the source of sulphuric acid providing:

• Substantially lower sulphuric acid cost estimated at $20-30/t including credit for steam and power generation used in the operation
• Acid plant produces more than enough steam and power for the entire operation
• Excess electricity (circa 20-30 MW) available to be sold into the grid providing an opportunity for substantial further credits toward operating costs
• Substantially lower overall processing costs
  o Fast payback on higher up-front capital to build a sulphuric acid plant.

Mechanical evaporators have been selected over solar evaporation ponds providing:

• A highly controlled and efficient process environment resulting in simplified downstream processing
• Smaller footprint and less environmental impact
• Substantially lower water consumption as water is captured and recycled
• Lower operating costs as heat/energy is provided by sulphuric acid plant.

Dry stack of vat leach rejects has been selected as the disposal method

• Lower capital cost, smaller footprint and less environmental impact than alternatives
• No tailings dam required.

The picture shows a view cross South Basin towards outcropping lithium-boron mineralisation.