By Helen Reid
JOHANNESBURG (Reuters) - Prices for aluminium ore bauxite from Guinea hit their highest in almost 18 months in top metals consumer China on Monday as buyers fretted about supply after a coup in the West African country, though no mines reported any disruption.
Guinea is the world's second-biggest producer of the raw material that is refined into alumina, a substance used to make aluminium metal, and is the top supplier to China.
Guinean bauxite for delivery to China was last assessed by Asian Metal at $50.50 a tonne, up 1% from Friday and the highest since March 16 last year. Prices are up about 16% this year.
The ousting of Guinea President Alpha Conde by an army unit on Sunday also extended a rally in aluminium prices to multi-year highs and boosted shares in aluminium producers Norsk Hydro and Rusal.
The unrest did not have any immediate impact on bauxite operations, which are key to Guinea's economy as its main foreign currency earner. The country produced 88 million tonnes of bauxite last year, according to mines ministry statistics.
"It is highly unlikely that the coup will have any major short-term impact on exports, which are always at the lowest part of the cycle in September with stockpiles depleted as the rainy season comes to an end," said Guinea bauxite industry specialist Bob Adam.
"Any incoming government will want to make sure that it doesn't jeopardise future earnings and investment."
Coup leader Mamady Doumbouya on Monday said that a curfew imposed in mining areas had been lifted.
Guinea's top bauxite producer Société Minière de Boké (SMB) did not immediately reply to a request for comment.
A spokesperson for Aluminium Corp of China (Chalco), the world's biggest producer of alumina, said its bauxite business in Guinea was operating normally.
Singapore's TOP International Holding, which owns two bauxite mines in Guinea, said operations were continuing "with minimal disruption" and the situation at sites in Boke and Boffa was stable.
A Compagnie des Bauxites de Guinée (CBG) spokesperson said its mines had not been affected by the turmoil.
U.S. aluminium giant Alcoa, joint owner of CBG, said it is monitoring the situation closely and is not aware of disruption to bauxite exports.
Rusal, which owns the Compagnie des Bauxites de Kindia (CBK) in Guinea, did not immediately respond to questions on whether its operations had been disrupted.
For a graphic on Guinea's bauxite production, click: https://tmsnrt.rs/3l1NSxW
AngloGold Ashanti said its Siguiri gold mine in Guinea was operating normally.
"We're monitoring the situation and are in close contact with the leadership of our mine in Guinea, which is operating normally," the gold miner said in a statement. Siguiri produced 117,000 ounces of gold in the first six months of this year.
The coup casts further doubt on the future for Guinea's many iron ore mine projects.
Rio Tinto, which is developing part of Guinea's huge Simandou iron ore project alongside Chinalco, declined to comment on how the overthrow might affect its plans in the country.
Andrew Gadd, senior steel analyst at CRU Group, said: "Sourcing the finances for Simandou has proved very difficult and the uncertainty generated by the current developments will challenge the commitment of interested parties."
Guy de Selliers, chairman of the Société des Mines de Fer de Guinée (SMFG), which is developing the Nimba iron ore project, said: "Irrespective of who is in charge, they will want this project to happen because it is good for the country."
De Selliers said that SMFG has political risk insurance through the World Bank's Multilateral Investment Guarantee Agency.
(Reporting by Helen Reid; Additional Reporting by Melanie Burton in Melbourne, Polina Devitt in Moscow, Mai Nguyen in Singapore and Tom Daly; Editing by Emelia Sithole-Matarise, Jane Merriman and David Goodman)