The mass is dangerous for humans and animals as it consists of heavy metals such as zinc and manganese.
The company has permission to send "black pulp" to Finland and Norway but not to Poland and Bulgaria, according to SR's Caliber and P4 Örebro.
- It is about illegal waste transports, says Ulrika Hagelin, administrator at the Swedish Environmental Protection Agency, to the radio.
Used as a building material
In Poland, 30 percent of the "black mass" has been recycled.
The rest has been used, among other things, to build roads in the country.
The company has previously been in windy weather in connection with the revelation that almost 2,000 tonnes of "black mass" were buried in Central Sweden. Four people responsible were sentenced to prison for a serious environmental crime, including a manager at the company in question.