Electrochemical Arsenic Immobilization for Sustainable Cobalt Production

Technology Summary

This technology introduces an electrochemical method for extracting cobalt from sulfoarsenide minerals, such as cobaltite (CoAsS), while simultaneously immobilizing arsenic as scorodite (FeAsO₄·2H₂O), a stable and low-solubility mineral form. The process enables cobalt production from arsenic-rich domestic sources by addressing both metal recovery and arsenic stabilization in a single system. The method operates at moderate temperatures (up to 70°C) and under ambient pressure conditions, without the need for chemical oxidants or high-pressure equipment.

Challenge

Domestic sources of cobalt remain largely untapped due to the presence of arsenic, which complicates extraction and disposal. Existing approaches to arsenic immobilization are energy-intensive, require high-pressure systems, and often depend on hazardous oxidants such as hydrogen peroxide. These limitations present cost, safety, and environmental challenges to scaling up cobalt production from arsenide-rich ores.

Solution

The system consists of a two-compartment electrochemical cell separated by an anion exchange or bipolar membrane. In the anode compartment, a sulfuric acid electrolyte (pH < 1) contains sulfoarsenide minerals and ferrous sulfate (FeSO₄). The electrochemical process proceeds as follows:

• Fe(II) is oxidized to Fe(III) at the anode via applied current.
• Fe(III) reacts with the mineral (e.g., CoAsS), releasing cobalt and dissolving arsenic.
• As(III) is oxidized to As(V) chemically or electrochemically.
• Fe(III) and As(V) combine to form scorodite, which precipitates from solution.

This process allows for the selective extraction of cobalt while co-precipitating arsenic in a stable, low-mobility form.

Key Advantages

• Integrated Processing: Combines metal extraction and arsenic immobilization in one step.
• Lower Input Requirements: Operates without external oxidants (e.g., H₂O₂) and under ambient pressure.
• Improved Environmental Management: Produces scorodite, which meets criteria for long-term arsenic stabilization.
• Reduced Energy Consumption: Eliminates the need for autoclaves and high-temperature hydrothermal systems.
• Scalable Design: Suitable for modular deployment and integration into hydrometallurgical workflows.
• Co-Recovery Potential: Supports extraction of additional metals, including Cu, Ag, Au, and rare earth elements.

Market Applications

This technology is relevant to several critical sectors that rely on secure and sustainable supply chains for cobalt and other metals:

• Cobalt and Critical Mineral Processing: Enables extraction from previously uneconomical arsenic-rich deposits.
• Battery Supply Chain: Supports domestic sourcing of cobalt for lithium-ion batteries in EVs and grid storage.
• Mining Operations: Applicable to mineral processors working with polymetallic ores in the Idaho Cobalt Belt and other arsenide-rich regions.
• Environmental Remediation: Potential applications in the treatment of arsenic-bearing waste from legacy mining sites.
• Defense and Energy Security: Supports national strategies for critical material independence and supply chain resilience.

Licensing

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