Indonesia is both the world’s largest nickel producer and the country with the biggest nickel reserves. (Most of Indonesia’s nickel output is currently Class 2 nickel, a low-purity type used for stainless steel. The country’s government and the mining sector are determined to transform its nickel industry to meet the rising demand for Class 1 nickel, a crucial component for electric vehicle (EV) batteries.)
Benchmark Mineral Intelligence’s Cobalt Forecast now suggests that cobalt production in the country could increase more than thirty-fold this decade. This would bring Indonesia into second place for cobalt mining, after the Democratic Republic of Congo.
This has been enabled by a growing number of high-pressure acid leaching (HPAL) projects which convert laterite ore into a mixed nickel-cobalt hydroxide precipitate. The HPAL process utilizes elevated temperatures (roughly 255 ˚C), elevated pressures (roughly 50 bar or 725 psi), and sulfuric acid to separate nickel and cobalt from the laterite ore.
Caldera Engineering explains that in the HPAL process, ore is mined and crushed to create a fine material. These fines are mixed with water to create a slurry which is then preheated. This hot slurry is pumped into an autoclave where the acid is added.
The slurry and acid then react as they flow through several compartments within the autoclave. The slurry takes approximately 60 minutes to complete the leaching process in the autoclave.
Upon leaving the high pressure and temperature atmosphere of the autoclave the slurry must be returned to atmospheric conditions. This is accomplished through two or more letdown/flash stages. Once the slurry is at atmospheric conditions it is washed and separated at which point the nickel and cobalt can be recovered from the liquid fraction.
Although HPAL is able to leach nickel and cobalt quickly from laterite ores, it is challenged by corrosion and erosion and energy requirements, as well as operational and maintenance issues.
HPAL has been used since 1961 when it was first put into commercial production at Moa Bay, Cuba.
Although there was scepticism over these projects initially, financing from China has helped them be a success, Benchmark says.
Indonesia’s nickel and cobalt are key components in global lithium ion battery supply chains. But the US “Inflation Reduction Act” has no provisions for Indonesian imports, which could disadvantage western automakers if Indonesia ends up supplying China instead.