Thermodynamic and economic analysis of the solar carbothermal and hydrometallurgy routes for zinc production

Abstract

This paper assesses the viability of the solar carbothermal reduction process for zinc production by comparing the thermodynamic efficiencies and levelized cost of zinc (LCOZ) with the solar hydrometallurgy routes. Four configurations of the hydrometallurgy route - concentrated solar power (CSP), photovoltaics (PV), solar-tariff, and grid-tariff based processes have been considered. The analysis is reported for the pilot (300 kWth), demonstration (5 MWth) and commercial (30 MWth) size systems. It is seen that the solar carbothermal process is thermodynamically more efficient than the hydrometallurgy route. The technology, however, is not viable at the pilot and demonstration scales and is likely to become cost-effective only at the commercial scale. For the commercial-scale plant, the LCOZ from the solar carbothermal process (172–204 $/ton) is lower than the solar (403 $/ton) and grid (281 $/ton) based hydrometallurgy processes. The cost of zinc obtained from solar thermochemical process is expected to further reduce by 7% in 2030. The bottom-up assessment shows the possibility of an 8–10% reduction. The solar carbothermal process appears to be promising at a commercial (30 MWth) scale. Therefore, the concept should now be demonstrated on a pilot scale for all sunshine hours in a year to boost confidence in the technology.