Authorities in eastern China have concluded that a deadly dust explosion at a metal-processing facility in January was the result of deliberate efforts by the company to evade safety regulations, according to an investigative report released by the Changzhou Emergency Management Bureau.

The blast at Changzhou Shenrong Metal Technology Co in Jiangsu province killed eight people and injured eight others. The investigation identified it as a "production safety responsibility incident" and cited the company's failure to comply with production equipment design requirements, leading to the accumulation of highly flammable aluminum alloy dust.

The report said Shenrong Co concealed production activities to evade supervision, a decision that directly contributed to the explosion. Other factors included inadequate emergency response, poor local oversight and lax industry regulation.

The explosion caused direct economic losses of more than 14.83 million yuan ($2.04 million), according to the report.

Shenrong Co, a subsidiary of Chongqing Bingrong Precision Manufacturing Co, specializes in polishing, sandblasting and anodizing components such as laptop and tablet casings. It employs over 180 workers and reported a production value of around 30 million yuan last year.

The company expanded its operations after renting a factory from Changzhou Tianwu Metal Technology Co in 2020. By 2022, Shenrong's rental space had grown to 5,600 square meters. The explosion occurred on the fourth floor of a building housing the company's workshops, warehouse and cafeteria, as well as Tianwu's idle processing area and dormitories.

The first incident occurred at 1:54 am on Jan 20, when aluminum alloy dust ignited in the polishing workshop and spread rapidly. Workers extinguished the fire and resumed operations without evacuating the premises.

A more powerful blast occurred at 3:32 am, triggered by aluminum dust accumulated in improperly operated polishing machines. Seven Shenrong employees and one Tianwu worker died, while eight others sustained injuries.

Investigators said Shenrong had violated the operations manual for its five-axis polishing machine, which was run in a dry mode, allowing combustible dust to accumulate. The unsafe mix of living and working areas and poor maintenance and cleaning systems further exacerbated the risks.

Seven individuals from Chongqing Bingron, Shenrong and Tianwu have been detained or placed under judicial supervision, the report said.