Integrative Approach to Metal Extraction and Electrification

Abstract

Molten sulfide electrolysis is a novel technology that produces metals directly from their sulfide minerals. A particular focus of the technology has been on copper metal extraction from chalcopyrite. Molten sulfide electrolysis is competing against established technologies in a legacy industry. The premise behind this work is that molten sulfide electrolysis has to maximize value to the copper supply chain in order to compete with established technologies. Two areas explored in this work are the synergy between molten sulfide electrolysis and the electricity grid and the synergy between molten sulfide electrolysis and the minerals processing of copper concentrates.

Discounted cash flow analysis is used to show the strength of molten sulfide electrolysis compared to traditional copper smelting techniques. The same technique is used to show that molten sulfide electrolysis of copper can be integrated into the electricity grid and provide additional value to the system. This is achieved by selectively idling the facility during periods of high electricity prices. This has the effect of trading off a higher capital cost with a lower operating cost.

Process models of a molten sulfide electrolysis copper processing facility were developed to determine how excess heat generated in the system can be used to melt excess gangue materials in the concentrate. It was found that the minerals processing of copper concentrates could be reduced under all base case scenarios. The excess heat of the system was found to be sensitive to the faradaic efficiency of the system and the electrical conductivity of the electrolyte. The faradaic efficiency of the system and the electrical conductivity of the electrolyte was experimentally determined over a range of operating conditions.

The primary focus of the development of the molten sulfide electrolysis technology has been on the copper supply chain. The lead and zinc supply chain was proposed as an additional market for the technology to explore. Experimental results showed that the technology could be used to produce lead and zinc metal from a molten sulfide electrolyte.