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A scientific organisation planned to investigate carbon reduction strategies for the production of nickel and cobalt as battery-grade sulfate salts. Elemental Engineering was brought in to aid the investigation by constructing steady-state models that represent production of the battery materials. The models required detailed calculations to provide a breakdown of CO2 emission sources within the plant to aid in the carbon footprint reduction project.
The investigative process included development of two flowsheets, the first being production of Ni and Co from ore via a mixed hydroxide intermediate, and the second via a mixed sulphide intermediate with both options involving an HPAL autoclave circuit. A final option was also considered utilising a sulphide concentrate to produce the battery materials.
On-site reagent plants were also modelled including a hydrogen, hydrogen sulphide and acid plant in order to fully model the site energy requirements and carbon footprint.
Following the development of the models, the Elemental Engineering team carried out an investigation and submitted a written report to summarise the results of the models, and proposed alternative strategies to mitigate carbon emissions and reduce energy consumption.
Four flowsheets were considered via two potential intermediate products, utilising nickel laterite ore or a sulphide concentrate to produce battery-grade nickel and cobalt sulfate salts. Scope 1, 2 and aspects of scope 3 carbon emission intensities at each step for all flowsheets were calculated and evaluated in order to provide a complete picture of carbon footprint across the site and facilitate the investigation into carbon reduction strategies.
Using process-modelling software that allows for accurate simulation of hydrometallurgical facilities, the Elemental Engineering team was able to accurately create a steady-state mass and energy balance of each option considered.
A primary focus of the project was to evaluate the carbon footprint of the nickel and cobalt production methods. As a result, a complex energy balance was performed in addition to the mass balance. This included accurate modelling of reaction enthalpies, heat losses to the environment and energy changes through evaporation.
An acid plant, hydrogen plant and hydrogen sulfate plant were also modelled accurately to provide a more accurate estimate of carbon emissions, as each of these would contribute significantly to each scope.
Elemental Engineering accurately provided the overall scope 1, 2 carbon emissions, as well as aspects of scope 3 emissions of all options considered via the different intermediate pathways and feed compositions.
This included a breakdown of all the individual sources of carbon emissions including emissions due to carbon evolution from the processing of carbonate ores and other chemical reactions (by plant section), power draw, emissions related to reagent delivery, and production and combustion of fuels.
Carbon offsets were also taken into account by considering any carbon capture in tailings facilities and electricity generation from excess steam production from the on-site acid plant.
Following the development of the steady-state models and carbon emissions data, the team analysed the results and made recommendations to the organisation on potential carbon reduction options at scope 1, 2 and 3.
With the in-depth information provided by Elemental Engineering, the organisation could see a clear path for reducing the carbon footprint of battery production for future nickel and cobalt production plants.