The explosion ripped through the workshop of Jingxin Mining Ltd. Co. in Fengyang county, Chuzhou city, at 3.17 am.
Most of the dead were employees, while the injured were residents living near the factory.
The privately-owned firm, which has 20 million yuan ($2.9 million) in fixed assets and about 100 employees, produces and processes about 300,000 tonnes of quartz sand every year.
Deccan Herald is on WhatsApp Channels| Join now for Breaking News & Editor's Picks