Benchmark spot iron ore prices stood at their lowest level since 2009, but appear set for a recovery as Chinese mills return to the market after being shut in order to cut pollution during a global summit in Beijing.

Industrial facilities including steel mills surrounding China’s capital were ordered to shut as early as Nov. 1 for the Asia-Pacific Economic Cooperation meeting that ended on Tuesday.

“Mills are being notified to restart their operation. They are now looking out to buy cargo, but some are still hesitant due to weakening steel sales,” said an iron ore trader in Singapore.

ANZ Bank said traders “remain cautious with steel mills reluctant to do any more than match their forward order books”.

Benchmark iron ore fines for immediate delivery to China .IO62-CNI=SI slipped 10 cents to $75.40 a tonne on Wednesday, the lowest level since June 2009, according to data compiled by the Steel Index.

Demand for fines, granular iron ore that must be treated before being fed into blast furnaces, had dropped as mills had to temporarily shut polluting sintering facilities for the APEC meeting, traders said. But that caused demand for iron ore lump, which can be fed directly into a blast furnace, to rise.

Premiums for iron ore lump sold at China’s ports rose to as high as 38 cents per dry metric tonne unit this week from 20.5 cents at the end of October, the Singapore trader said.

“There’s crazy-hot demand due to sinter capacity being limited. However with sintering capacity restarting, you will start to see lump premiums coming off,” he said.