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2011年1月31日,事故发生时,两个夜班机修工在检修发生跑偏故障的斗式提升机。该提升机位于退火炉的下游, 用于将细铁粉输送到成品仓。 当时两个工人各自站在斗式提升机的平台上。提升机启动的时候,扬起了粉尘。粉尘被点燃,将两名工人烧伤。该斗式提升机的除尘系统在两天前出现故障,该故障导致了这次事故。

The first incident occurred on January 31 as two maintenance mechanics on the overnight shift inspected a bucket elevator that had been reported to be malfunctioning due to a misaligned belt. The bucket elevator, located downstream of an annealing furnace, conveyed fine iron powder to storage bins. The two mechanics were standing alone on an elevated platform near the top of the bucket elevator, which had been shut down and was out of service until maintenance personnel could inspect it. When the bucket elevator was restarted the movement immediately lofted combustible iron dust into the air. The dust ignited and the flames engulfed the workers causing their injuries. A dust collector associated with the elevator was reported to have been out of service for the two days leading to the incident.



The second incident occurred less than two months later on March 29 when a plant engineer, who was replacing igniters on a furnace, was engulfed in combustible dust which ignited. In the course of the furnace work, he inadvertently dislodged iron dust which had accumulated on elevated surfaces near the furnace. He experienced serious burns and bruises as a result of this second event; a contractor witnessed the fireball but escaped without injury.



An explosion was reported earlier today at the plant, injuring five, including three who were in critical condition at the Vanderbilt University Medical Center burn unit in Nashville.According to a company official, today’s accident took place in the vicinity of one of the facility’s furnaces.

2011年6月3日 CSB召开新闻发布会

Rafael Moure-Eraso(新闻发布会主持人):





Rafael Moure-Eraso (Chairman of News Conference):

We are here today to update the media and the public on the status of our ongoing investigation into the explosion and ensuing fire that occurred at the Hoeganaes facility on Friday, May 27 in Gallatin, Tennessee. Tragically, two workers died and a third was gravely injured.

CSB and its experts have done extensive testing on the metal dust from the facility. Tests show that powder samples collected from the sites of both the January and March accidents were combustible and could be exploded under test conditions.

Combustible dust is an insidious workplace hazard when it accumulates on surfaces, especially elevated surfaces. Since the CSB was established in 1998, three of the four deadliest accidents we have investigated were determined to be combustible dust explosions.

A wide range of common combustible materials can explode in finely powdered form, including metals, wood, coal, flour, sugar, plastics, and many chemicals and pharmaceuticals.

Johnnie Banks(CSB负责该事故的调查组长):






Johnnie Banks (Team Lead, the investigator-in-charge for this case):

Briefly, the plant collects scrap iron, which is then melted, sprayed into powder form, and then annealed using hydrogen gas using a large continuous furnace. This powder is then further milled, packaged, and eventually sold as a final product.

During all three of our trips to the Hoeganaes plant my team observed alarming quantities of metal dust within close proximity to the incident locations. This was of particular concern as metal dust flash fires present a greater burn injury threat than flammable gas or vapor flash fires. Metal dust fires have the potential to radiate more heat and some metals burn at extremely high temperatures in comparison to other combustible materials. In addition to visible dust particles in the air, 2 to 3-inch layers of dust were observed on flat surfaces, rafters, and railings throughout the facility.

According to witness interviews the incident took place on Friday, May 27, 2011, between 6:30 and 6:40 am. At about 6:10 am, two annealing operators heard a hissing sound in a trench that housed a number of process pipes carrying hydrogen, nitrogen, and cooling water. When the operators heard the hissing sound, they summoned plant maintenance personnel to lift a cover over the area where the gas leak was thought to have occurred.

After several attempts to lift the cover with a pry bar were unsuccessful, a call went out to get a forklift. The cover was attached to the forklift with a metal chain and raised. As the cover was pried opened, an explosion occurred. Some witnesses saw a flash of light; some heard a muffled boom and felt the building shaking from the explosion. The building filled with dust and the lights went out. Witnesses saw burning dust raining down from above.

The initial explosion, we now know, involved hydrogen gas that had been leaking into the trench from a large hole in the vent pipe. However, the witness statements as well as the physical evidence leave no doubt that combustible iron dust was also involved in the aftermath of the explosion.


2011/02/16:  CSB Continues Investigation of Fatal Fire at Hoeganaes Corporation Located Outside of Nashville, Tennessee

2011/05/11: U.S. Chemical Safety Board Continues Investigation of Two Accidents at the Hoeganaes Corporation Facility

2011/05/27: CSB Deploys to a Third Accident at Hoeganaes Corporation Metal Powder Plant in Gallatin, Tennessee

2011/06/03: Statement for the news conference






海格纳士公司是全球领先的铁基粉末制造商,产品广泛应用于全球的粉末冶金、化工及焊接等产业。 事发工厂有175名员工,主要生产雾化铁粉,销售给汽车和其他行业用于粉末冶金方法生产金属零部件。


美国化学安全与危害调查委员会(CSB)是美国联邦的独立机构,主要职能是调查重大化学安全事故。其成员由总统提名,在参议员表决通过。CSB调查化学安全事故的所有方面,包括设备故障在内的自然原因(physical causes),也包括规章制度、工业标准和安全管理系统等方面的不足。在事故调查之后,CSB不负责褒奖和惩罚,而是向工厂、工业机构、工会(labor groups)和美国职业安全与健康管理局和美国环保局等法规制定机构提供建议。CSB的事故调查报告可通过 www.csb.gov 获取。


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