By 2017, five years into this conflict, a criminal trial was going on in the Talvivaara mine, owned then by Talvivaara Mining Company Plc. Under scrutiny in the trial were the construction and use of Talvivaara's gypsum waste pond, for alleged scheduled and uncontrolled dumping of effluents into nature, as well as issues surrounding the handling and placement of the mine's various waste components. Prosecutors claimed that Talvivaara bosses committed their first environmental crimes as early as 2004 when the mine was in its planning and building stages. Prosecutors demanded suspended prison sentences of 1 year for Talvivaara Mining Company ex-CEO Pekka Perä, 10 months for ex-CEO Harri Natunen and 8 months for an ex-division chief for aggravated environmental degradation. The accused denied the charges. By 22 March 2018 (reported for instance by Xinhua) a high court in Rovaniemi, northern Finland, sentenced Pekka Pera, founder and original director of Talvivaara mining company, to half a year in prison on probation on account of severe environmental pollution. Starting in 2015, the lawsuit was considered the most significant environmental criminal case in Finland. Two executives of the mining company were fined. A lower court had also fined Pera previously. The operation in Talvivaara nickel and zinc mine began in Sotkamo, Northern Finland in 2008. It used a water bio-diluting process in separating the ore. The waste reservoirs were problematic from the start. They overfilled due to rainwater, and contaminated water leaked to the environment. The wastewater included metal and gypsum. Major leaks occurred in 2008, 2010, 2012, and 2013.
One of the major toxic leaks that began in November 2012 at Europe’s largest nickel mine in north-eastern Finland had become an environmental disaster. The leak was from a gypsum waste pond, which was contaminated with nickel, uranium, and other toxic metals. The mine discharged huge amounts of toxic effluent into the nearby surroundings and lakes. The extraction of heavy metals has resulted in pollution with the uranium concentration in the effluent rising to up to 200 times its normal level in the bottom and surface waters.
Earlier in 2012 one of the mine’s employees died from hydrogen sulfide poisoning in the mining area and dozens of dead water birds were discovered in the open pond. Dust and obnoxious odors from the mine dispersed over a wide area, while the mine’s impact on the waterway was detected over 100 kilometers downstream.
The Finnish National Institute for Health and Welfare (THL) declared that wastewater leaked from the Talvivaara mining "has no immediate serious effects on human health". However, the Finnish Radiation and Nuclear Authority (STUK) reported uranium levels 3.5 times higher than the recommended limit of 100 micrograms per liter, but not high enough to be acutely dangerous to humans. The company pledged to cover all the damages caused by the leak.
The leakage prompted organizations such as the Finnish Association for Nature Conservation (FANC) to call on the government to intervene. Despite attempts by the company to stop the leaks, leakages continued from April 2013 onwards. In May 2013 FANC demanded the government to close the mine expressing concerns about environmental monitoring which they say had been left to business interests.
Finland's Ministry of Employment and the Economy informed that the company's operations cannot continue before further studies are completed. He said that results from wastewater samples indicate that the environmental permits issued were not in line with its current operations. The Safety Investigation Authority, a government agency responsible for the investigation of major accidents, started an investigation into Talvivaara. Prosecutors were considering the case against Talvivaara Mining in January 2014. Talvivaara subsequently received penalty payments on wastewater management.
Despite huge operating losses (some USD 950 million in 2013), and the environmental problems, Talvivaara received a new permit from the Northern Finland Regional State Administrative Agency in April 2014 to extract uranium. However, this was subject to an appeals process. In the meantime, Talvivaara continued to operate under the previous permit despite opposition from the public and politicians. In July 2014 Talvivaara cancelled the listing of its shares on the London Stock Exchange. Furthermore, the mounting debts of Talvivaara have resulted in a court order for the company to submit to the Corporate Reorganisation Administrator by September 2014 its plans for a long-term financial solution. Afterward, it would be resolved whether the corporate reorganization will enable the company to solicit funding at home and abroad in order to stay afloat, or face bankruptcy.
Talvivaara mining company went into official bankruptcy in 2015. At that moment, the state-owned company Terrafame Oy bought the mine. In May 2016, the Finnish government decided to prepare the closedown of the mine. However, this never happened. Just a few months after Terrafame Oy. bought the mine, they were already producing more than the former owner. In March 2017, the mining subsidiary of Talvivaara mining was renamed Ahtium. In 2018, the latter was also declared bankrupt.