In this Thursday, May 8, 2014 photo, Iranian coal miners push metal carts to be loaded with coal at a mine near the city of Zirab 212 kilometers (132 miles) northeast of the capital Tehran, on a mountain in Mazandaran province, Iran. International sanctions linked to the decade-long dispute over Iran's nuclear program have hindered the import of heavy machinery and modern technology in all sectors, and coal mining is no exception. (Photo by Ebrahim Noroozi/AP Photo)

In this Thursday, May 8, 2014 photo, a coal miner lights a cigarette after a long of work at a mine near the city of Zirab 212 kilometers (132 miles) northeast of the capital Tehran, on a mountain in Mazandaran province northern Iran. Around 1,200 miners work across 10 mines in the Mazandaran province, in a mountainous, verdant area. More than 12,000 tons of coal is extracted from the mines each month, almost all of which is shipped south for use in Iran's steel industry. (Photo by Ebrahim Noroozi/AP Photo)

In this Wednesday, May 7, 2014 photo, an Iranian coal miner with his face smeared black from coal poses for a photograph at a mine near the city of Zirab 212 kilometers (132 miles) northeast of the capital Tehran, on a mountain in Mazandaran province, Iran. The workers who put in long hours in often dangerous conditions and make just $300 a month, little more than minimum wage. (Photo by Ebrahim Noroozi/AP Photo)

In this Thursday, May 8, 2014 photo, an Iranian coal miner pushes an old metal cart to be loaded with coal at a mine near the city of Zirab 212 kilometers (132 miles) northeast of the capital Tehran on a mountain in Mazandaran province, Iran. A miner said they move up to 100 tons a day. (Photo by Ebrahim Noroozi/AP Photo)

In this Tuesday, August 19, 2014 photo, Iranian coal miners eat lunch at a mine near the city of Zirab 212 kilometers (132 miles) northeast of the capital Tehran, on a mountain in Mazandaran province, Iran. (Photo by Ebrahim Noroozi/AP Photo)

In this Thursday, May 8, 2014 photo, an Iranian coal miner moves wagons to be loaded with coal at a mine near the city of Zirab 212 kilometers (132 miles) northeast of the capital Tehran, on a mountain in Mazandaran province, Iran. International sanctions linked to the decade-long dispute over Iran's nuclear program have hindered the import of heavy machinery and modern technology in all sectors, and coal mining is no exception. (Photo by Ebrahim Noroozi/AP Photo)

In this Tuesday, May 6, 2014 photo, an Iranian coal miner smokes a cigarette during his break at a mine near the city of Zirab 212 kilometers (132 miles) northeast of the capital Tehran, on a mountain in Mazandaran province, Iran. International sanctions linked to the decade-long dispute over Iran's nuclear program have hindered the import of heavy machinery and modern technology in all sectors, and coal mining is no exception. The decision to privatize the industry 10 years ago has further squeezed miners, who work often in dangerous conditions – and make just $300 a month, little more than minimum wage. (Photo by Ebrahim Noroozi/AP Photo)

In this Monday, August 18, 2014 photo, an Iranian coal miner works inside a mine near the city of Zirab 212 kilometers (132 miles) northeast of the capital Tehran, on a mountain in Mazandaran province, Iran. The miners tunnel deep into the mountains, working in dark, narrow passageways where the risk of toxic gases and cave-ins is never far from their minds. (Photo by Ebrahim Noroozi/AP Photo)

In this Tuesday, August 19, 2014 photo, an Iranian coal miner works inside a mine near the city of Zirab 212 kilometers (132 miles) northeast of the capital Tehran, on a mountain in Mazandaran province, Iran. (Photo by Ebrahim Noroozi/AP Photo)

In this Monday, August 18, 2014 photo, an Iranian coal miner pushes a metal cart loaded with coal at a mine near the city of Zirab 212 kilometers (132 miles) northeast of the capital Tehran, on a mountain in Mazandaran province, Iran. The miner move up to 100 tons of coal a day. (Photo by Ebrahim Noroozi/AP Photo)

In this Thursday, May 8, 2014 photo, an Iranian coal miner takes a break at a mine near the city of Zirab 212 kilometers (132 miles) northeast of the capital Tehran, on a mountain in Mazandaran province, Iran. (Photo by Ebrahim Noroozi/AP Photo)

In this Monday, August 18, 2014 photo, Iranian coal miners pose for a photograph at a mine on a mountain in Mazandaran province, near the city of Zirab 212 kilometers (132 miles) northeast of the capital Tehran, Iran. (Photo by Ebrahim Noroozi/AP Photo)

In this Tuesday, August 19, 2014 photo, an Iranian coal miner smokes a cigarette during a break at a mine on a mountain in Mazandaran province, near the city of Zirab 212 kilometers (132 miles) northeast of the capital Tehran, Iran. (Photo by Ebrahim Noroozi/AP Photo)

In this Tuesday, May 6, 2014 photo, Iranian coal miners rest during a break at a mine on a mountain in Mazandaran province, near the city of Zirab, 212 kilometers (132 miles) northeast of the capital Tehran, Iran. The miners put in long hours in often dangerous conditions and make just $300 a month, little more than minimum wage. (Photo by Ebrahim Noroozi/AP Photo)

In this Tuesday, May 6, 2014 photo, an Iranian coal miner takes a shower while others prepare to go home after a long day of work at a mine on a mountain in Mazandaran province, near the city of Zirab, 212 kilometers (132 miles) northeast of the capital Tehran Iran. Around 1,200 miners work across 10 mines in the Mazandaran province, in a mountainous, verdant area. More than 12,000 tons of coal is extracted from the mines each month, almost all of which is shipped south for use in Iran's steel industry. (Photo by Ebrahim Noroozi/AP Photo)

In this Wednesday, May 7, 2014 photo, Iranian coal miners pose for a photograph before taking a shower after a long day of work at a mine on a mountain in Mazandaran province, near the city of Zirab 212 kilometers (132 miles) northeast of the capital Tehran Iran. (Photo by Ebrahim Noroozi/AP Photo)

In this Tuesday, May 6, 2014 photo, Iranian coal miners shower after a long day of work at a mine on a mountain in Mazandaran province, near the city of Zirab, 212 kilometers (132 miles) northeast of the capital Tehran, Iran. (Photo by Ebrahim Noroozi/AP Photo)

In this Wednesday, May 7, 2014 photo, an Iranian coal miner stops collecting logs to pose for a photograph at a mine on a mountain in Mazandaran province, near the city of Zirab, 212 kilometers (132 miles) northeast of the capital Tehran, Iran. (Photo by Ebrahim Noroozi/AP Photo)

In this Thursday, May 8, 2014 photo, Iranian coal miners make their way home after a long day of work at a mine on a mountain in Mazandaran province, near the city of Zirab, 212 kilometers (132 miles) northeast of the capital Tehran. Iran's ministry of industry, mines and commerce says it has plans for improving the working conditions of miners alongside a drive to boost the production of minerals. Deputy Minister Jafar Sargheini says the ministry will grant loans and aid as part of the four-year plan for the sector, which will include safety improvements. (Photo by Ebrahim Noroozi/AP Photo)