Life cycle assessment and process simulation of prospective battery-grade cobalt sulfate production from Co-Au ores in Finland

Marja Rinne,Heini Elomaa,Mari Lundström

doi:10.1007/s11367-021-01965-3

Abstract

PurposeThe soaring demand for cobalt for lithium-ion batteries has increased interest in the utilization of non-conventional cobalt sources. Such raw materials include complex ores containing minerals such as cobaltite and skutterudite, which, while rare, occur around the world, including in Finland, Canada, and the USA. The goal of this study was to evaluate the cradle-to-gate impacts of cobalt sulfate recovery from unutilized cobalt- and gold-bearing ores with the use of process simulation.MethodsA literature analysis was conducted to establish the state-of-the-art processing methods for complex cobalt ores containing significant amounts of gold. The drafted process was simulated using HSC Sim software to obtain a mass and energy balance, which was compiled into a life cycle inventory (LCI). The environmental impact categories (global warming, acidification, eutrophication, ozone depletion, photochemical smog creation, water use) were calculated in GaBi software. Uncertainty regarding the possible future raw material composition was studied, and the simulation was used to investigate process performance and to evaluate the effect of variation in the process parameters on the environmental impact indicators.Results and discussionThe results indicated that the main cobalt mineral type (cobaltite, linnaeite) had only minor effects on the evaluated impact categories. With cobaltite-dominated ores (High As case), the global warming potential (GWP) was estimated to be 20.9 kg CO2-eq, of which 12.7 kg CO2-eq was attributed to the hydrometallurgical process. With linnaeite-dominated ores, the equivalent values were 20.4 kg CO2-eq and 11.0 kg CO2-eq. The production of a high grade concentrate was observed to greatly decrease the impacts of the hydrometallurgical process, but the cobalt losses in the beneficiation stage and the mineral processing impacts would likely increase. The simulation showed that there is still potential to improve the cobalt recovery (to approximately 96%), which would also affect the indicator values.ConclusionsThe impacts were estimated prior to intensive metallurgical testing to determine the possible high impact areas in the process. Based on this, it is suggested that, during hydrometallurgical processing, improved treatment of cobalt-containing wash waters and the optimization of oxygen utilization efficiency in pressure leaching are the most significant ways to decrease the environmental impacts. Optimal solutions for the concentrate could be found when experimental data on the minerals processing steps becomes available.

Highlights

The ongoing transition to electric mobility is projected to massively increase the demand for battery metals, such as cobalt, nickel, and lithium, many of which are considered critical raw materials in the EU (European Commission 2020)
Increasing and sustainable mine production of battery metals is necessary for widespread electrification
Arsenical ores are rare, they can be found around the world, including in Norway (Groru 1997), Morocco, and Canada (Johnson et al 2020), which could make them a potentially attractive raw material with the current development

Summary

Introduction

The ongoing transition to electric mobility is projected to massively increase the demand for battery metals, such as cobalt, nickel, and lithium, many of which are considered critical raw materials in the EU (European Commission 2020). The Blackbird mine in Idaho, USA, is perhaps the best-known example of the utilization of cobaltite ores, but the mine was closed in 1967 despite still containing considerable amounts of copper and cobalt (Gray et al 2012). Most of the gold by-production originates from the copper industry, but it is recovered in nickel, lead, and platinum group metal operations (Ferron 2005; Kyriakis 2005). Past examples of gold-bearing cobalt ores are known from Canada, these are rare (Ferron 2005)

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