The “7·21” poisoning incident at Gansu Jinshi Chemical Co., Ltd. (Case analysis)

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I. Accident Investigation and Analysis (I) Overview of the Accident 1. Introduction to the accident: At around 22:40 on July 21, 2013, a serious carbon monoxide poisoning incident occurred in the caustic soda production workshop of Gansu Jinshi Chemical Co., Ltd., resulting in 4 deaths and 4 injuries, with direct economic losses amounting to approximately 3.67 million yuan. 2. Causes of the accident: (1) Direct causes: ① During operation of the dryer, the frequency converter of the exhaust fan tripped, resulting in insufficient exhaust volume. This led to incomplete combustion of coal powder inside the dryer, which in turn generated toxic and harmful gases such as carbon monoxide. These gases could not be expelled and, driven by the pressure provided by the Roots pump at the furnace head, flowed back into the maintenance pit on the lower floor through the casing of the elevator. As a result, the concentration of toxic and harmful gases like carbon monoxide in that pit became extremely high. The operators worked there without any protective measures, which led to poisoning incidents. ②The failure to follow approval procedures for significant changes in processes and equipment; the addition of new drying equipment without adequate justification or proper design; and the unauthorized implementation of technical modifications—all these factors contributed to the accident. Additionally, no risk identification was conducted regarding the main hazardous factors associated with this process, and there were no proper measures in place to address potential consequences should the induced draft fan fail and stop operating. These factors constitute one of the direct causes of the accident. ③The maintenance pit on the negative first floor of the elevator is not equipped with toxic gas detectors, nor does it have any forced mechanical ventilation system. The emergency equipment for dealing with poisoning incidents, such as portable gas masks and air respirators, is insufficiently available in the production area. Production workers and rescue personnel lack safety awareness, employ improper rescue methods, and carry out rescue efforts recklessly, resulting in the expansion of the accident. (2) Indirect causes: ① Inadequate implementation of the enterprise’s primary responsibilities. The principal person in charge of the enterprise failed to fulfill his/her responsibilities as the primary person responsible for safety production; approval procedures were not followed for any significant changes in processes, equipment, or facilities. There was insufficient oversight and inspection of the company’s safety production activities, and no thorough efforts were made to identify and address potential hazards, nor to crack down on illegal practices or conduct comprehensive safety inspections. Potential accident risks were not detected and eliminated in a timely manner. The management systems and operating procedures related to the maintenance, repair, and modification of safety facilities and equipment were not properly implemented, and no drills were carried out using the company’s emergency response plan for hazardous chemical production accidents. ②Safety training and education are inadequate. “The content of the “level 3” safety training and education is not targeted enough; no specialized safety training is provided for new employees working with drying equipment. The workers lack knowledge regarding the prevention of toxic and harmful gases, have weak safety awareness, and engage in illegal operations. ③Special operation management is inadequate. No safety technical procedures for working in confined spaces were established in the hoist maintenance pit; the permit system for working in confined spaces was not implemented, and no tests were conducted to detect toxic and harmful gases present in those spaces – thus illegal operations were carried out. ④Technical management is inadequate. There is a lack of understanding of the safety technical characteristics of dried equipment that has undergone technical upgrades; furthermore, no safety design assessment nor HAZOP analysis has been carried out on dried equipment that was not designed properly or is being used in an improper manner. The use, maintenance, and inspection of safety equipment such as the frequency converter and circuit breakers for the exhaust fans in drying equipment are not carried out in a timely or proper manner. No obvious safety warning signs were installed on the drying equipment in the caustic soda workshop, which has significant risk factors, and no measures were taken in a timely manner in response to early signs of accidents. ⑤Emergency rescue management is inadequate. The emergency response plans for hazardous chemicals lack specificity and practicality; these plans have not been tested in practice, the emergency equipment available is not up to standard, and the rescue personnel lack the necessary knowledge for carrying out rescue operations. Zhang, the deputy director of the company’s chemical plant, and Liu, the head of the drying section in the caustic soda production area of the same plant, gave illegal instructions and carried out rescue efforts in a reckless manner. ⑥Safety inspections are not properly carried out. The relevant departments in Minle County, such as the **, the Management Committee of Minle County’s Ecological Industrial Park, the County Work Safety Supervision Bureau, and the County Industry and Information Technology Bureau, have failed to fulfill their responsibilities for local supervision, comprehensive supervision, and industry-specific supervision. Insufficient depth and care were shown in tasks such as hazard identification, cracking down on illegal activities, and comprehensive safety inspections, resulting in accident hazards not being detected and eliminated in a timely manner. (II) Basic Information 1. Information on the units involved in the accident: Gansu Jinshi Chemical Co., Ltd. is a private enterprise. The legal representative of the company is Han Mou, and its registered address is in Liuba High-Tech Development Zone, Minle County. Both the \"Enterprise Legal Person Business License\" (registration number: 620722200001491) and the \"Work Safety License\" (number: (Gan) WH Anxu Zhi) are still valid. The scope of the safety production license covers sodium dichromate, chromic anhydride, and caustic sulfide. The company has two manufacturing facilities for chemicals and cement, with over 1,000 employees currently working there. The chemical plant includes production lines for calcium-free calcined sodium aluminate, anhydrous chromic acid, chromium green oxide, caustic sulfide, aluminum hydroxide, and ferrochrome. The caustic soda production line of Gansu Jinshi Chemical Co., Ltd. produces caustic soda using mirabilite, a by-product generated during the production of chromium salts. The main raw materials are mirabilite and raw coal; no drying equipment was available when the plant was first built. In May 2007, the Municipal Work Safety Supervision Bureau organized a special safety inspection team composed of the Municipal Quality Supervision Bureau, the Municipal Public Security Fire Brigade, the Municipal Lightning Protection Center, the Work Safety Supervision Bureau and Quality Supervision Bureau of Minle County, the county’s public security fire brigade, as well as experts in hazardous chemicals, to conduct a special inspection and acceptance of the safety facilities related to the caustic soda production line construction project, ensuring that these facilities were installed in accordance with the principle of \"simultaneous construction, operation, and use\". In the second half of 2012, the company switched to using semi-coke instead of raw coal for production. Due to the large fluctuations in the moisture content of semi-coke during the production process, the company carried out technical modifications to its feeding system and added drying equipment for the semi-coke feedstock without authorization. This drying equipment uses the hot flue gas generated by coal powder combustion to supply heat, which causes the moisture in semi-coke to vaporize through heat exchange within the dryer; the moisture is then carried away by the exhaust fan, thereby achieving the purpose of removing moisture. If combustion is incomplete during this period, toxic and harmful gases such as carbon monoxide are produced. The drying equipment for the raw lignite was constructed in October 2012 and put into operation in November. (III) Time sequence of the accident: Date and time – At 17:00 on July 21st, Liu Guo, the supervisor of the drying section in the caustic soda production area at Gansu Jinshi Chemical Co., Ltd., along with Yi Mudong, Zhang Mou, and Zhang Er Mou, were working the night shift in that same drying section. At 22:35 on July 21, Liu Guo arranged for Yi Moudong and Zhang to clean the slag waste in the hoist pit; Yi Moudong went into the pit to carry out the cleaning, while Liu and Zhang were responsible for supervision. Zhang Er Mou collected waste at the discharge outlet of the drying furnace. At 22:40 on July 21, Zhang discovered Yi lying unconscious in the pit. Liu, Zhang, and Zhang Er, who was there to collect waste, went down into the pit to rescue Yi. Zhang and Zhang Er performed CPR on Yi; after about two to three minutes, Yi regained consciousness. Zhang Er noticed that Liu Guo was not there, so he went to the bottom of the pit’s ladder and found Liu Guo unconscious there. Zhang Er went with Wang, a worker from the caustic soda workshop who was passing by and delivering coke, to the pit in an attempt to pull Liu out. Zhang also fainted in the pit, while Wang climbed out of it and called to inform Jia, the supervisor of the caustic soda workshop. Zhang Er ran to the ferrochrome workshop to get help. Subsequently, Jia asked Ren, the supervisor of the ferrochrome workshop, to drive to the accident site. Along the way, Ren used his mobile phone to report the incident to Liu Jian, the company’s on-duty manager and head of the Technical Equipment Department, Zhang Tian, the deputy director of the chemical plant, Zhu, the head of the Production and Safety Department, and Zhang Zhong, the company’s general manager. Zhang Zhong, the general manager of the company, received a call at his home in Ganzhou District, Zhangye City. He immediately dialed the emergency number \"120\" and called Yang, the deputy director of the chemical plant located in Minle, to rush to the accident site for rescue. At the same time, he informed Han, the chairman of the company based in Zhangye, about the incident; Han went straight to the city hospital to arrange for emergency treatment, while Zhang Tian rushed back to the company. After arriving at the scene, Ren and Jia covered their mouths and noses with towels and went down into the pit to rescue people; Jia fainted in the pit as well. Since Ren alone could not provide assistance, he climbed out of the pit. At that time, Zhang Tianmo, the deputy director of the chemical production plant, and Liu Jianmo from the Technical Equipment Department who was on night shift also arrived at the scene. Liu Jianmo called to arrange for warehouse staff to deliver rescue supplies such as gas masks and oxygen cylinders to the site, and he organized people to set up fans in the pit where the elevator was located. Zhang Tianmo, wearing a regular mask, went down into the pit to rescue people but fainted there. At that moment, Zhang Er called for Wang, Yi Miliang, Yi Milin, and Liu Quanmou – four people in total – to go down with Ren and pull Jia out. Liu Quanmou, Yi Miliang, Yi Milin, and Wang fainted on the ground. Soon after, the managers from various workshops arrived one after another. Led by chief engineer Huang, Liu, Tian, Pang, Qi, Shi, and others took action to carry out rescue efforts: they soaked masks in water, had people wear gas masks, pumped oxygen into the pit, and set up ventilators, thereby managing to pull Liu Guomou, Zhang, and Zhang Tianmou out of the pit one after another. During the rescue operation, Liu Guo, Zhang, Zhang Tian, Liu Quan, Yi Miliang, Liu Ji, Jia, and Wang suffered poisoning and fell into a coma. At 23:10 on July 21, the company immediately used 3 vehicles to transport all the victims of poisoning to Zhangye People’s Hospital for treatment. Along the way, they were transferred to the 120 ambulances from Zhangye People’s Hospital that had come to provide assistance. Zhang Tianmu, Liu Guomu, Zhang Mou, and Liu Quanmu died despite efforts to save them at Zhangye People’s Hospital, while Yi Miliang, Liu Jimu, Jia Mou, and Wang Mou were admitted to Zhangye People’s Hospital for further treatment. (IV) Accident losses: This poisoning incident resulted in 4 deaths and 4 injuries, with direct economic losses of approximately 3.67 million yuan. http://www.chemicalsafety.org.cn/uploads/allimg/161116/7-161116110131936.jpg Figure 1: Drying section http://www.chemicalsafety.org.cn/uploads/allimg/161116/7-161116110146348.jpg Figure 2: Discharge outlet of the drying furnace http://www.chemicalsafety.org.cn/uploads/allimg/161116/7-1611161102063B.jpg Figure 3: Pedestrian ladder in the pit http://www.chemicalsafety.org.cn/uploads/allimg/161116/7-161116110222643.jpg Figure 4: Bottom of the pit (V) Analysis of accident causes 1. Analysis of direct causes ① During operation of the dryer, the frequency converter of the exhaust fan tripped, resulting in insufficient exhaust volume. This led to incomplete combustion of coal powder inside the dryer, generating toxic and harmful gases such as carbon monoxide. These gases could not be expelled and, under the pressure provided by the Roots pump at the furnace head, flowed back into the maintenance pit on the lower floor through the elevator housing. As a result, the concentration of toxic and harmful gases such as carbon monoxide in the pit became extremely high. The operators worked there without any protective measures, which led to poisoning accidents. ②The failure to follow approval procedures for significant changes in processes and equipment; the addition of new drying equipment without adequate justification or proper design; and the unauthorized implementation of technical modifications—all these factors contributed to the accident. Additionally, no risk identification was conducted regarding the main hazardous factors associated with this process, and there were no proper measures in place to address potential consequences should the induced draft fan fail and stop operating. These factors constitute one of the direct causes of the accident. ③The maintenance pit on the negative first floor of the elevator is not equipped with toxic gas detectors, nor does it have any forced mechanical ventilation system. The emergency equipment for dealing with poisoning incidents, such as portable gas masks and air respirators, is insufficiently available in the production area. Production workers and rescue personnel lack safety awareness, employ improper rescue methods, and carry out rescue efforts recklessly, resulting in the expansion of the accident. 2. Analysis of indirect causes: ① Inadequate implementation of the enterprise’s primary responsibilities. The principal person in charge of the enterprise failed to fulfill his/her responsibilities as the primary person responsible for safety production; approval procedures were not followed for any significant changes in processes, equipment, or facilities. There was insufficient oversight and inspection of the company’s safety production activities, and no thorough efforts were made to identify and address potential hazards, nor to crack down on illegal practices or conduct comprehensive safety inspections. Potential accident risks were not detected and eliminated in a timely manner. The management systems and operating procedures related to the maintenance, repair, and modification of safety facilities and equipment were not properly implemented, and no drills were carried out using the company’s emergency response plan for hazardous chemical production accidents. ②Safety training and education are inadequate. “The content of the “level 3” safety training and education is not targeted enough; no specialized safety training is provided for new employees working with drying equipment. The workers lack knowledge regarding the prevention of toxic and harmful gases, have weak safety awareness, and engage in illegal operations. ③Special operation management is inadequate. No safety technical procedures for working in confined spaces were established in the hoist maintenance pit; the permit system for working in confined spaces was not implemented, and no tests were conducted to detect toxic and harmful gases present in those spaces – thus illegal operations were carried out. ④Technical management is inadequate. There is a lack of understanding of the safety technical characteristics of dried equipment that has undergone technical upgrades; furthermore, no safety design assessment nor HAZOP analysis has been carried out on dried equipment that was not designed properly or is being used in an improper manner. The use, maintenance, and inspection of safety equipment such as the frequency converter and circuit breakers for the exhaust fans in drying equipment are not carried out in a timely or proper manner. No obvious safety warning signs were installed on the drying equipment in the caustic soda workshop, which has significant risk factors, and no measures were taken in a timely manner in response to early signs of accidents. ⑤Emergency rescue management is inadequate. The emergency response plans for hazardous chemicals lack specificity and practicality; these plans have not been tested in practice, the emergency equipment available is not up to standard, and the rescue personnel lack the necessary knowledge for carrying out rescue operations. Zhang Tianren, the deputy director of the company’s chemical plant, and Liu Guorong, the head of the drying section in the caustic soda production area of the same plant, gave illegal instructions and carried out rescue efforts in a reckless manner. ⑥Safety inspections are not properly carried out. The relevant departments in Minle County, such as the **, the Management Committee of Minle County’s Ecological Industrial Park, the County Work Safety Supervision Bureau, and the County Industry and Information Technology Bureau, have failed to fulfill their responsibilities for local supervision, comprehensive supervision, and industry-specific supervision. Insufficient depth and care were shown in tasks such as hazard identification, cracking down on illegal activities, and comprehensive safety inspections, resulting in accident hazards not being detected and eliminated in a timely manner. II. Emergency Response to the Incident: At around 22:40, Zhang noticed that Yi had collapsed in the pit. Liu, Zhang, and another person who was there to collect waste went down into the pit to rescue Yi. Zhang and another person performed CPR on Yi; after about two to three minutes, Yi regained consciousness. Zhang realized that Liu was not there, so he went to the pit and found Liu unconscious at the bottom of the ladder leading down into it. Zhang then went down into the pit with Wang, a worker from the caustic soda workshop who was passing by and delivering coke, in an attempt to pull Liu out. Zhang fainted in the pit, while Wang climbed out and called to inform Jia, the supervisor of the caustic soda workshop. Zhang ran to the ferrochrome workshop to get help. Subsequently, Jia asked Ren, the supervisor of the ferrochrome workshop, to drive to the accident site. Along the way, Ren used his mobile phone to inform the company’s on-duty manager, the head of the technical equipment department, Zhang, the deputy director of the chemical plant, Zhu, and the company’s general manager about the incident. Upon receiving the call at his home in Ganzhou District, Zhangye City, the company’s general manager, Mr. Zhang, immediately dialed the emergency number \"120\". He also called Mr. Yang, the deputy director of the chemical plant located in Minle, to urge him to rush to the accident site for rescue efforts. At the same time, he informed Mr. Han, the company’s chairman who was in Zhangye, about the incident; Mr. Han went straight to the city hospital to arrange for emergency treatment, while Mr. Zhang rushed back to the company. After arriving at the scene, Ren and Jia covered their mouths and noses with towels and went down into the pit to rescue people; Jia fainted in the pit as well. Since Ren alone could not provide assistance, he climbed out of the pit. At this time, Zhang, the deputy director of the chemical plant’s branch factory, and Liu from the Technology and Equipment Department, who was on night duty, also rushed to the scene. Liu made a phone call to instruct warehouse staff to deliver rescue supplies such as gas masks and oxygen cylinders to the site, and organized personnel to set up fans in the elevator pit. When Zhang Tianren, wearing an ordinary mask, descended into the pit to rescue people, he fainted there. At that moment, Zhang called for Wang, Yi, Yi, and Liu – a total of four people – and together they went down to pull Jia out. Liu, Yi, Yi, and Wang fainted on the ground. Soon after, the managers from various workshops arrived one after another. Led by chief engineer Huang, Liu, Tian, Pang, Qi, Shi, and others took action to carry out rescue efforts: they soaked masks in water, had people wear gas masks, injected oxygen into the pit, and set up ventilators, eventually pulling Liu, Zhang, and Zhang out of the pit one after another. During the rescue operation, Liu, Zhang, Zhang, Liu, Yi, Liu, Jia, and Wang, who participated in the efforts, were poisoned and fell into a coma. At around 11:10 p.m., the company immediately dispatched three vehicles to transport all the poisoned individuals to Zhangye People’s Hospital for treatment. Along the way, they were transferred to ambulances from Zhangye People’s Hospital that had rushed to the scene. Despite efforts at treatment, Zhang Mou, Liu Mou, Zhang Mou, and Liu Mou succumbed to their injuries. Yi Mou, Liu Mou, Jia Mou, and Wang Mou were hospitalized at Zhangye People’s Hospital for treatment. III. Reflections and Recommendations (1) The relevant departments and enterprises in Minle County must draw profound lessons from this incident. It is imperative to earnestly implement the principle that “human lives are of paramount importance; development must never come at the cost of human lives.” This must be regarded as an unbreakable red line.” It is necessary to truly align thoughts and actions with the decision-making and deployment of ****, the State Council, the provincial Party committee and provincial ** authorities, as well as the municipal Party committee and municipal ** authorities. We must further enhance our sense of urgency and responsibility in ensuring the safe production of hazardous chemicals, learn from such incidents, take preventive measures early on, and implement more effective strategies to strengthen supervision over safety production, thereby preventing similar accidents from occurring. (II) It is recommended that Minle County **carefully follow** the requirements set out in relevant provincial and municipal documents, conduct a thorough self-inspection of its work related to identifying and addressing potential hazards, cracking down on illegal activities, and carrying out comprehensive safety inspections; identify any gaps in its work practices and areas that require attention, and carry out proper follow-up checks. At the same time, in line with the overall requirements of \"full coverage, zero tolerance, strict law enforcement, and emphasis on practical results,\" efforts to conduct thorough inspections for work safety in the field of hazardous chemicals are further intensified. In accordance with relevant laws, regulations, procedures, standards, and technical requirements, key areas prone to accidents, critical locations, and essential processes are carefully inspected. Any identified hazards and problems are recorded in a special ledger, and corrective actions, responsibilities, funding, deadlines, and emergency plans are established to ensure that these issues are resolved within set time frames. Enterprises should be urged to conduct thorough self-inspections and self-corrections; those that fail to do so thoroughly or that fail to identify all potential risks properly shall be ordered to carry out further inspections ； For those that have failed to comply with the requirement that inspections must be followed up by re-inspections, re-inspections should be carried out immediately in accordance with the principle that \"the person who conducts the inspection is responsible for it.\" ； Those who refuse to comply with the orders for rectification shall be ordered to suspend production and operations in accordance with the law, and subject to severe penalties as provided by law ； For any major safety hazards that have not been rectified on schedule, they must be shut down in accordance with the requirements of the \"four musts\" as mandated by law; it is absolutely unacceptable for safety inspections to be conducted perfunctorily or as a mere formality. (III) Minle County **must earnestly fulfill its responsibilities for local supervision of work safety, and instruct the relevant departments to assume and carry out their duties in terms of industry-specific and comprehensive supervision of work safety in accordance with the law. It is necessary to strengthen guidance, coordination, supervision, and inspection of hazardous chemical production and operation units within its jurisdiction. At the same time, it is necessary to urge hazardous chemical enterprises within the jurisdiction to earnestly assume their primary responsibility for safety production, improve various safety management systems and operating procedures, strictly implement the \"three simultaneities\" principle for safety facilities in construction projects as well as the approval processes for major changes in processes, facilities, and equipment. Safety design assessments should be conducted on existing chemical plants that lack proper design, in order to eliminate potential safety hazards at the source. (IV) Minle County ** and its relevant departments shall urge chemical enterprises to earnestly implement technical specifications and safety measures related to startup, shutdown, inspection, and maintenance, strictly adhere to safety standards for hazardous operations such as hot work and entry into confined spaces, rigorously enforce relevant technical regulations including those concerning risk analysis and identification as well as the approval process for special operation permits, and effectively strengthen supervision at the sites where these operations are carried out. All hazardous chemical enterprises must be equipped with air respirators, gas masks, and necessary safety protection devices at their work sites, and these devices must be regularly inspected and calibrated to ensure they are in good condition. Strengthen the monitoring of toxic and harmful gases at sites where hazardous chemicals are handled, to resolutely prevent accidents such as poisoning and asphyxiation. It is necessary to strengthen safety management throughout the entire chemical production process, and to fully apply Hazard and Operability Study (HAZOP) techniques. (5) Minle County **should instruct the relevant departments to strictly adhere to the regulations set by the ** province and city, to raise the entry requirements for employees working in hazardous chemicals enterprises to an appropriate level, thereby ensuring the basic competence of such employees. It is necessary to urge enterprises to earnestly implement the \"three-level\" safety education and training system for employees, and to continuously strengthen the safety training for personnel in these \"three types of positions.\" This will enable them to truly understand the potential hazards in their work environments and positions, as well as the corresponding preventive measures, emergency response plans, and safety management systems, thereby enhancing employees’ safety awareness and their ability to protect themselves. It is necessary to further improve emergency response plans, conduct regular emergency drills, increase investment in emergency preparedness, enhance the stockpiles of emergency supplies and equipment, and boost the company’s capacity to handle accidents and carry out emergency rescue operations.