Europe's largest copper producer expects operating pre-tax earnings in its 2018/19 fiscal year to fall significantly by more than 15% compared with the previous year.
Higher prices for a basket of Lonmin's metals and a weaker South African rand helped the London-listed miner to an annual pre-tax profit in 2018, its first since 2013.
Sailingstone, its second biggest investor, flagged its vote in an open letter last month, citing governance issues and the board's lack of engagement with minority investors.
The world's second largest bullion miner is preparing its Zambian copper mine Lumwana for sale in the second half of 2019, looking to target Chinese buyers.
Pembroke has been talking to potential customers and is also open to selling a stake in the mine that will eventually produce 15 million tonnes of high-quality coking coal a year.
The company said on Tuesday first-half headline earnings is expected to rise at least 160%, boosted by higher iron ore export prices and a weaker rand/US dollar exchange rate.
The US faces stiff challenges as it moves to create its own electric vehicle supply chain, with the extent of the country's metal reserves largely unknown and only a few facilities to process minerals and produce batteries.