The story
The plant was founded in 1958. In 1997, the company was sold to Cumerio a company from Belgium for US$80 million becoming Cumerio Med; at the time it was Bulgaria's largest copper smelting company, producing around 240,000 tonnes of smelted copper and around 60,000 tonnes of copper cathodes each year. In 2007, the company was bought by German company Norddeutsche Affinerie (now Aurubis).
From Wikipedia’s article on Cumerio Med, shared under CC BY-SA 4.0.3