Depending on the coal quality, the value of the contract is expected to range between 35 and 40 million marka ($22.4 million/20.5 million euro), Alumina said in a Facebook notice on Wednesday.
Alumina and RMU Banovici cooperate since the end of 2012. The coal miner has supplied about 1,750,000 tonnes of coal to Alumina in the past 11 years.
Alumina's main activity is the production of alumina, hydrate, zeolite, sodium silicates and water glass.
RMU Banovici's shares last traded on the Sarajevo bourse on December 15, when they closed 13.06% lower at 5.99 marka.
(1 euro = 1.956 marka)