The firm, which traditionally offers direct equity investments, had expanded its focus to provide short-term, flexible financing solutions across the capital structure, including credit facilities.
Appian is prepared to offer support from US$50 million to $300 million, including equity, bridge loans and other forms of credit.
"The spread of coronavirus has had a profound impact on people's lives, economies, commodity prices and financial markets worldwide," Appian said.
"We are also conscious that the broader mining industry is already under pressure. There has been a demand shock and prices have fallen. Restrictions on the movement of people have forced companies to change working patterns. Supply disruption could increase further if the virus spreads to key commodity producing regions in Latin America and Africa.
"It is precisely in times like this that long-term capital and through-the-cycle thinking are required to support high quality businesses and management teams."
Appian's current portfolio includes operating and development assets across base, precious and specialty metals in Latin America, North America, Australia and Africa.
"We remain constructive on the medium and long-term outlook of the sector and look forward to continuing our engagement with industry participants worldwide," it said.
The company has offices in London, Toronto, Lima, Belo Horizonte and Sydney, as well as technical teams in Mexico and South Africa.