Inside Nevada North: A Deep Dive into the 86,000 tpa Lithium Carbonate Processing Circuit

Overview

Nestled in the mineral-rich landscape of Elko County, Nevada, the Nevada North Lithium Project represents a monumental stride in securing the United States’ domestic supply of critical battery metals. This ambitious venture, detailed in a comprehensive NI 43-101 Technical Report, is poised to become a cornerstone of the North American electric vehicle (EV) supply chain. Operated under the auspices of a dedicated development company, the project focuses on extracting lithium from unique claystone deposits, a resource that has historically been more challenging to process than brines or hard rock spodumene. The strategic location in Nevada places it within a renowned mining jurisdiction with established infrastructure and a skilled workforce, offering significant logistical advantages. The facility is designed for a staggering 42-year mine life, with plans to process over 443 million dry tonnes of material. Its production is phased, targeting an initial output of 43,000 tonnes per annum (tpa) of battery-grade lithium carbonate (LCE) before scaling up to a massive 86,000 tpa, with a peak production target of 109,100 tpa expected in Year 6. This project is not just a mining operation; it is a sophisticated chemical plant designed to tackle the complex metallurgy of lithium clays, employing acid leaching and a multi-stage purification process to produce a high-purity product essential for lithium-ion batteries. Its development is critical for meeting the soaring global demand for EVs and energy storage, marking Nevada North as a project of national significance and a key player in the global energy transition.

Key Process Stages

The Nevada North Lithium Project employs a complex and innovative flowsheet specifically designed to liberate and recover lithium from claystone ore. The process can be broadly divided into two main sections: beneficiation to upgrade the ore and a multi-step chemical plant to extract and purify the lithium into a saleable carbonate product. The entire circuit is designed for high efficiency and incorporates a Zero Liquid Discharge (ZLD) philosophy to minimize environmental impact.

• Stage 1: Comminution and Beneficiation: Run-of-Mine (ROM) ore is first crushed by a feeder breaker and a mineral sizer (toothed roll crusher) to reduce the particle size to a P80 of 25 mm. The crushed ore is then mixed with water and fed to a log washer for initial hydration and clay liberation. The material subsequently reports to a multi-cell attrition scrubber, which uses aggressive particle-on-particle contact to liberate lithium-bearing clay from coarse gangue material. The slurry is screened to remove any remaining +25 mm material.
• Stage 2: Classification and Dewatering: The scrubbed slurry is pumped to a classification circuit consisting of hydroclassifiers and multi-stage gravity concentrators. This circuit is designed to reject approximately 25% of the feed mass as coarse, low-lithium gangue. The target lithium-bearing clay fines (minus 75 microns) report to a high-rate thickener, which increases the pulp density to 22-25% solids. The thickener underflow is further dewatered by horizontal decanter centrifuges to achieve a cake density of 50% solids. This cake is then repulped for feeding to the leach circuit.
• Stage 3: Acid Leaching and Neutralization: The upgraded clay slurry is leached in a series of four agitated tanks with sulfuric acid (H₂SO₄) at a temperature of 75-90°C, generated by the heat of reaction. A dosage of 481 kg of acid per tonne of dry feed solids dissolves an estimated 93% of the lithium. The acidic slurry (10-60 g/L H₂SO₄) then enters a six-stage neutralization circuit. First, ground limestone slurry is added to raise the pH to 3-4. Subsequently, milk-of-lime and recycled magnesium hydroxide are added to complete the neutralization to a final pH of 6.5, precipitating out impurities like iron and aluminum.
• Stage 4: Counter-Current Decantation (CCD) and Filtration: The neutralized slurry is clarified, and the underflow is sent to a 7-stage CCD washing circuit to recover soluble lithium entrained with the solids. Flocculant is added to each stage to enhance settling. The washed solids from the final CCD stage are filtered using recessed chamber filter presses to produce a filter cake with 61% solids, which is sent to the tailings facility. The combined PLS (Pregnant Leach Solution) from the neutralization clarifier and CCD overflows is sent forward for purification.
• Stage 5: Purification and Lithium Carbonate Production: The PLS is first concentrated by evaporation. Nearly half of the magnesium is then removed as magnesium sulfate heptahydrate salts via crystallization and centrifugation. The remaining magnesium is precipitated as hydroxide using lime. Calcium is removed by precipitation with soda ash. An ion exchange (IX) polishing step ensures divalent cations (Ca²⁺, Mg²⁺) are reduced to near-zero levels. The purified lithium sulfate solution is reacted with soda ash in a crystallizer to produce primary lithium carbonate. This product undergoes a bicarbonation step (reacting with CO₂ to form soluble LiHCO₃) and a second crystallization to produce high-purity, battery-grade Li₂CO₃. The final product is dried, micronized, and packaged. Mother liquors are sent to a ZLD crystallizer to recover sodium and potassium sulfate salts, with all residual lithium recycled back to the process.

Critical Data

The following table presents the key technical and operational parameters that define the scale and efficiency of the Nevada North Lithium Project’s processing circuit, as outlined in the Preliminary Economic Assessment.

Additional Interesting Data and Summary

The Nevada North Lithium Project is a feat of modern metallurgical engineering, balancing large-scale production with sophisticated chemistry. Beyond the impressive throughput and recovery figures, the project incorporates several noteworthy aspects. The reagent consumption over the 42-year life of mine (LOM) is substantial, highlighting the project’s scale. The annual consumption includes approximately 597,584 tonnes of sulfur for acid production, 650,406 tonnes of limestone, and 192,336 tonnes of quicklime for neutralization and precipitation. The production of battery-grade lithium carbonate requires 165,981 tonnes of soda ash annually. Water management is a critical component, with the entire process designed for maximum recycle. The plant’s total water consumption is estimated at 6,420 acre-feet per annum (AFA) for both phases, with a significant portion of this being makeup water for evaporation and moisture lost in the tailings. The project embraces a Zero Liquid Discharge (ZLD) design, ensuring that all process water is recycled and any waste salts (magnesium sulfate, sodium sulfate, potassium sulfate) are crystallized, dewatered, and co-disposed with the neutralized clay tailings in a dedicated Clay Tailings Filter Stack (CTFS). From an energy perspective, the on-site sulfuric acid plant is a key feature. It not only produces the essential leaching reagent but also generates high-pressure steam. This steam is passed through a turbine generator to produce a significant portion of the site’s power needs, greatly enhancing the project’s energy efficiency and reducing its grid power dependency and carbon footprint. The project’s economic impact is considerable, with an estimated capital investment required to build both phases and the creation of long-term jobs in the region. As a domestic source of a critical mineral, the Nevada North Lithium Project strengthens national supply chain security and supports the broader goals of decarbonization and sustainable energy adoption.

Source: NI 43-101 Technical Report | Preliminary Economic Assessment | Project: Nevada North Lithium Project | Date: May 2025

Further Reading

• Nevada North Lithium Project, US
• BLM approves Nevada North Lithium Exploration Project
• Nevada lithium mining expands with estimated $87B project