RB Kolubara (full legal name: Privredno društvo za proizvodnju, preradu i transport uglja Rudarski basen Kolubara d.o.o. Lazarevac; Company for the production, processing and transport of coal mine basin Kolubara Ltd. Lazarevac) is a Serbian coal mining and smelting complex with headquarters in Lazarevac, Kolubara District. The mine has coal reserves amounting to 2.2 billion tonnes of lignite, one of the largest lignite reserves in Europe, and it produces 22.6 million tonnes of coal per year.