The move by the police and army came one week after a landslide at the Kamoto Copper Company (KCC) concession, majority-owned by a Glencore subsidiary, killed 43 people, prompting a government pledge to swiftly remove the miners.
Glencore said in a statement that Democratic Republic of Congo's army had been deployed to an area around KCC. It said the company had insisted soldiers exercise restraint and respect human rights.
Speaking to reporters in the southeastern city of Kolwezi, where KCC is located, General Philemon Yav said the army's intervention was required to defend Congo's economic interests and support the police, who have at times been overwhelmed by the thousands of illegal miners present in some mines.
"By all means, we are going to kick them out of our strategic mines so they don't harm our economy," Yav said.
The army said 20,000 miners were evicted from KCC. Glencore estimates about 2,000 illegal miners enter the mine every day.
Earlier this week, the miners defied an army deadline to leave the mine. Activists said they feared the standoff would lead to violent clashes and human rights abuses.
Emmanuel Umpula, the director of watchdog group African Resources Watch, and Mike Lameki, a civil society activist in Kolwezi, said security forces opened fire to disperse the protesters, who were demanding a new concession to exploit.
It was unclear whether they had fired live rounds or rubber bullets, or if there were any injuries. Lameki said about 20 miners were arrested.
After being dispersed from the governor's office in the morning, Lameki said, the miners headed to the neighbourhood of Kasulo.
"On the way, they met up with friends who had come from other parts of town," he said. "Then they started pillaging."
Richard Muyej, the governor of Lualaba province where Kolwezi is located, promised to provide the miners alternative concessions, but they are sceptical that those areas will be big enough or contain ore of high enough quality to support them.
Rights activists have criticised the expulsion, saying it did not address factors such as poverty and unemployment, that push people to brave dangerous conditions in mines.
Last week, the army evicted thousands of miners from China Molybdenum nearby Tenke Fungurume mine.
General John Numbi, who led the operation, said the soldiers did not fire a single shot. African Resources Watch said they did and cited local villagers as saying three people died from gunshot wounds.
Last Thursday's accident at KCC briefly sent Glencore's shares tumbling 7%, underscoring foreign investors' exposure to illegal mining activity on their properties.
The Lualaba government estimates that 170,000 informal miners operate in the province. They burrow deep underground with rudimentary tools, leading to frequent accidents.
Congo produces more than half the world's cobalt, a key component in electric car and other electronic batteries, but is one of the world's least developed countries, afflicted by corruption and conflict.
(Reporting by Aaron Ross; Editing by Janet Lawrence and Emelia Sithole-Matarise)
By Aaron Ross