Brazilian mining giant Vale lost more than US$18 billion of its value Monday in a dramatic share plunge on the São Paulo stock exchange as investors reacted to the collapse of one of its dams that killed scores and left hundreds missing.

The 24.5 percent drop followed an eight percent dive on the New York Stock Exchange on Friday, the day the disaster occurred. The Brazilian bourse was closed that day for a public holiday.

US-listed shares in Vale continued to fall Monday. They were 17.5 percent lower just before close of trading.

Vale, the world's biggest iron ore miner, has seen its reputation severely tarnished by the deadly accident – the second involving a company-owned mine in the southeast Brazilian state of Minas Gerais in just over three years.

It announced it was suspending dividend payments to shareholders and performance-related bonuses to executives.

Brazilian authorities separately have frozen a total 11 billion reais – around US$3 billion – in Vale assets in anticipation of compensation it will likely have to fork out.

A tsunami of mineral-laced mud broke through a dam at an iron-ore mine owned by Vale near the town of Brumadinho on January 25.

The official toll from the disaster was 60 dead and 292 missing as of Monday.

In 2015, a dam at another mine jointly owned by the company ruptured, killing 19 and polluting hundreds of kilometres of river, causing what is considered the worst environmental disaster Brazil has ever seen.

Vale and its partner BHP are still paying for that accident, with compensation and fines costing over $6 billion and lawsuits ongoing.

In terms of human loss, this latest disaster was worse.

The company is mourning lost personnel in the latest disaster, as the overwhelming majority of those dead and missing were mine workers.

Many of the victims were eating lunch at the site when millions of tons of sludge, a byproduct of mining, burst through the dam and engulfed the administrative area they were in.

Emergency workers also found a company minivan buried in the mud with bodies inside.

Profitable company

The dam that broke was built in 1976 and was in the process of being decommissioned. Vale said it had passed a structural safety inspection four months ago, which was confirmed by Tuev Sued, the German firm that carried it out.

Vale, headquartered in Rio de Janeiro, made $5.5 billion in profits, on revenue of US$34 billion, in 2017, the last full-year results available.

That net result was 38 percent higher than the previous year, evidence of a bounce back after a sharp commodities slump in 2015 that forced the company into cost-cutting.

A mining specialist at the State University of Rio de Janeiro, Luiz Jardim Wanderley, told AFP that there was "a tendency for companies, in that period of commodity prices falling, to cut safety and maintenance budgets."

He said that, of the 450 dams in Minas Gerais state, "we have a relatively high number of dams that are doubtful or in inappropriate conditions."

'Life matters most'

Vale is one of the top miners in the world, behind BHP and Rio Tinto, both Anglo-Australian groups.

Apart from iron ore, which feeds China's appetite, Vale also mines nickel, copper and other metals.

The company has a workforce of 76,500 in 30 countries and also operates hydroelectric plants, rail lines, ports and ships to get its products to market.

Vale started out in Minas Gerais – a major mining state, as its name declares in Portuguese – in 1942 as a state-owned company called Companhia Vale do Rio Doce. It was privatised in 1997.

On its corporate website, Vale says it has a "passion for people and the planet."

It says that "life matters most" and it aspires to "do what is right."

- TIMES/AFP