【Accident Case Analysis】The Asphyxiation and Poisoning Accident on \"11·11\" in the 06 Waste Liquid Desulfurization Environmental Protection Research Project

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I. Accident Investigation and Analysis (I) Overview of the Accident 1. Brief Introduction to the Accident Around 2 a.m. on November 11, 2012, during the cleanup of a decolorization liquid tank as part of the waste liquid desulfurization environmental protection research project carried out by Shenhua Mengxi Coal Chemical Co., Ltd., three people died from asphyxiation and poisoning, resulting in direct economic losses of 3.5 million yuan. 2. Causes of the accident: (1) The direct cause was that while cleaning the activated carbon in the decolorization liquid tank, team leader Mao entered a confined space (the decolorization liquid tank) in violation of safety procedures – without conducting any gas testing, obtaining an appropriate work permit, using proper protective equipment, or having anyone supervise the operation. This led to poisoning by hydrogen sulfide gas. Zhang and Yang also suffered poisoning as they lacked basic safety knowledge, did not wear protective gear, and attempted to carry out rescue efforts recklessly, resulting in the deaths of all three people. (2) Indirect causes: ① Beijing Aishihézhong Environmental Protection Technology Company has imperfect rules and regulations; the safety management responsibilities of managers at all levels are unclear, resulting in chaotic safety management ； ②Beijing Aishezhongrong Environmental Protection Technology Company fails to provide adequate safety training; some of its employees have not received third-level safety education, and the company does not inform them about the hazards associated with their jobs. These employees lack the necessary safety knowledge and skills, have weak safety awareness, and poor professional competence ； ③Beijing Aishezhonghong Environmental Protection Technology Company lacks the necessary emergency rescue facilities, and has failed to provide its employees with the required personal protective equipment ； ④Beijing Aishezhonghong Environmental Protection Technology Company has not conducted any drills for emergency response plans, nor does it have any on-site handling procedures for specific tasks. In the event of an emergency, there are no skills or measures available to deal with such situations, and in case of an urgent situation, there is no one to provide unified command on site, leading to reckless attempts at rescue ； ⑤Shenhua Mengxi Company and Beijing Aishezhonghong Environmental Protection Technology Co., Ltd. only included safety provisions in their Cooperation Agreement, but there is no separate safety agreement ； Managers at all levels fail to provide adequate supervision for the company’s safety measures ； ⑥Shenhua Mengxi Company failed to comply with the legal requirements regarding the \"three simultaneities\" principle for safe production ； ⑦The Mengxi Management Committee of Eqi, Eqi’s Economic and Information Bureau, Eqi’s Work Safety Supervision Bureau, and the Mengxi Branch of Eqi’s Environmental Protection Bureau failed to provide adequate supervision over the wastewater desulfurization project carried out by Shenhua Mengxi Coal Chemical Co., Ltd. (II) Basic Information 1. Information on the units involved in the accident: Beijing Aishizhonghong Environmental Protection Technology Co., Ltd. (hereinafter referred to as Beijing Aishi Company) was registered and established in June 2011; its legal representative is Chen, who possesses the qualifications of a legal person. The main business areas include technology development, technical services, technology transfer, technical consulting, technical training, and technology promotion ； Selling products developed independently, etc. Organization code: 57685549-0. Company type: Private joint-stock enterprise. Shenhua Mengxi Coal Chemical Co., Ltd. (hereinafter referred to as Shenhua Mengxi Company) was registered in 2002; its legal representative is Mr. Jiang. Its main business activities include coal mining, coal washing and processing, coking, and the production of coal chemical products. It has an annual production capacity of 1.7 million tons of coke and 100,000 tons of methanol, and holds all necessary licenses. Organization code: 74013317-5. Company type: State-owned joint-stock enterprise. In accordance with the requirements of the local environmental protection authorities, Shenhua Mengxi Company is required to achieve zero discharge of industrial wastewater. As a result, after conducting investigations and research, Shenhua Mengxi Company decided to entrust Beijing AIS Technology Co., Ltd. with the desulfurization of its industrial wastewater using its patented technology. To facilitate cooperation with Shenhua Mengxi Company, this company registered another entity, Beijing AIS Hezhong Environmental Protection Technology Co., Ltd., which will be responsible for carrying out the wastewater desulfurization project for Shenhua Mengxi Company. The project was approved by the Economic and Information Technology Bureau of Eqi County; it is capable of processing 80 tons of waste liquid per day, with a total investment of 16.5 million yuan. Beijing AIS Company is responsible for investing in and operating this project, while Shenhua Mengxi Company provides Beijing AIS Company with office space free of charge (worth 2.5 million yuan). Beijing AIS Company is in charge of the tasks related to waste liquid treatment and product recycling, and it will transfer these assets to Shenhua Mengxi Company free of charge upon the expiration of the agreed operating period. Project location: South side of the office building of the Second Coking Plant of Shenhua Mengxi Coal Chemical Co., Ltd., in Mengxi Town, Etoke Banner, Ordos City, Inner Mongolia Autonomous Region. Beijing AIS Company and Shenhua Mengxi Company signed a cooperation agreement on May 25, 2011, and began construction; testing and commissioning started in March 2012. The company currently has 48 employees. (III) Timeline of the incident: Date and time – At 20:00 on November 10th, Mao, the shift supervisor at Beijing AiSi Company, called Chairman Tong to report that the decolorization effect of the waste liquid during the production process was poor and did not meet the required standards. The likely cause was a leak in the pipeline connecting the decolorization tank, which led to the accumulation of activated carbon inside the tank and thus affected its decolorization capacity. After that, Mao Huahu began to clean the decolorization tank. From November 11th at 01:00, team leader Mao had cleaned the decolorization solution tank three times. Around 2 o’clock, Mao Huhu entered the workshop and asked Guo, who was working there, to find two woven bags. Then Mao put on a dust mask and went into the decolorization solution tank to clean the activated carbon. At 01:05 on November 11, Guo climbed into the decolorization solution tank and saw Mao lying motionless at the bottom of it. He then called Zhang, the person in charge of centrifugation, over. Zhang tied a rope around his waist and entered the tank; by that time, Mao was no longer responding. As Zhang tried to pull Mao out, he himself fainted. Guo was unable to drag Zhang out, so he immediately left the tank and called 110, 119, and 120 for help, At the same time asking other people in the factory to assist as well. Workers Wang and Yang, who were responsible for dissolution, ran over to the decolorization liquid tank upon hearing the cries. Yang asked Wang to use his phone as a light source while he entered the tank to carry out rescue efforts. When Wang saw Yang lift Zhang up, he began to convulse throughout his body and then collapsed to the ground. At that time, the factory fire brigade of Shenhua Mengxi Company arrived at the scene and entered the tank wearing air respirators to carry out rescue efforts. The 120 emergency service in Mengxi Town also arrived, and the Wuhai Special Operations Squad likewise showed up; they used specialized equipment to rescue the three people. Doctors confirmed that the three had no vital signs. (IV) Accident losses: The accident resulted in 3 deaths and direct economic losses of 3.5 million yuan. (5) Analysis of the accident causes 1. Analysis of the direct causes: In the process of recovering salts from waste liquids for Shenhua Mengxi Company, Beijing AIS Company carried out a physical separation process to extract sodium thiosulfate and sodium thiocyanate from the desulfurization waste liquids. Sodium thiosulfate was recovered through evaporation, while sodium thiocyanate was separated by dissolution in ethanol; no chemical reactions took place, nor were any new substances formed. However, the desulfurization waste liquid contains hydrogen sulfide; when left to stand or cooled, this hydrogen sulfide separates from the activated carbon. Since hydrogen sulfide is denser than air, it settles to the bottom of the tank as the liquid is discharged, and it may not be detectable at the top of the tank. Beijing AIS Company lacks effective safety management for the production of salt from waste liquids and the maintenance processes. While cleaning the activated carbon in the decolorization liquid tank, team leader Mao entered a confined space (the decolorization liquid tank) in violation of safety procedures – without conducting any gas testing, obtaining an appropriate work permit, using proper protective equipment, or having anyone supervise the operation. This led to poisoning by hydrogen sulfide gas. Zhang and Yang also suffered poisoning as they attempted to carry out rescue efforts without any knowledge of safety protocols and without wearing any protective gear, resulting in the death of all three people. 2. Analysis of indirect causes: ① Beijing Aishihézhong Environmental Protection Technology Company has imperfect rules and regulations; the safety management responsibilities of managers at all levels are unclear, resulting in chaotic safety management ； ②Beijing Aishezhongrong Environmental Protection Technology Company fails to provide adequate safety training; some of its employees have not received third-level safety education, and the company does not inform them about the hazards associated with their jobs. These employees lack the necessary safety knowledge and skills, have weak safety awareness, and poor professional competence ； ③Beijing Aishezhonghong Environmental Protection Technology Company lacks the necessary emergency rescue facilities, and has failed to provide its employees with the required personal protective equipment ； ④Beijing Aishezhonghong Environmental Protection Technology Company has not conducted any drills for emergency response plans, nor does it have any on-site handling procedures for specific tasks. In the event of an emergency, there are no skills or measures available to deal with such situations, and in case of an urgent situation, there is no one to provide unified command on site, leading to reckless attempts at rescue ； ⑤Shenhua Mengxi Company and Beijing Aishezhonghong Environmental Protection Technology Co., Ltd. only included safety provisions in their Cooperation Agreement, but there is no separate safety agreement ； Managers at all levels fail to provide adequate supervision for the company’s safety measures ； ⑥Shenhua Mengxi Company failed to comply with the legal requirements regarding the \"three simultaneities\" principle for safe production ； ⑦The Mengxi Management Committee of Eqi, Eqi’s Economic and Information Bureau, Eqi’s Work Safety Supervision Bureau, and the Mengxi Branch of Eqi’s Environmental Protection Bureau failed to provide adequate supervision over the wastewater desulfurization project carried out by Shenhua Mengxi Coal Chemical Co., Ltd. II. Emergency rescue in case of an accident: Guo climbed into the decolorization solution tank and saw Mao lying motionless at the bottom of the tank. He then called Zhang, the person responsible for operating the centrifuge, over. Zhang tied a rope around his waist and entered the tank; by that time, Mao was no longer responding. As Zhang tried to pull Mao out, he himself fainted. Guo was unable to drag Zhang out, so he immediately left the tank and called 110, 119, and 120 for help, while also asking other people in the factory to assist. Workers Wang and Yang, who were responsible for dissolution, ran over to the decolorization liquid tank upon hearing the cries. Yang asked Wang to use his phone as a light source while he entered the tank to carry out rescue efforts. When Wang saw Yang lift Zhang up, he began to convulse throughout his body and then collapsed to the ground. At that time, the factory fire brigade of Shenhua Mengxi Company arrived at the scene and entered the tank wearing air respirators to carry out rescue efforts. The 120 emergency service in Mengxi Town also arrived, and the Wuhai Special Operations Squad likewise showed up; they used specialized equipment to rescue the three people. Doctors confirmed that the three had no vital signs. III. Reflections and Recommendations (1) Enterprises should carefully summarize and learn from the lessons of accidents, conduct thorough inspections to identify and rectify potential safety hazards, carry out internal reforms within the company, standardize the safety practices of all employees, clarify the safety responsibilities associated with each position, further improve the safety management systems at construction sites, and ensure that corporate leaders fulfill their safety responsibilities. This will help create a corporate culture in which management truly values safety and all employees are proactive in prioritizing it. (II) Enterprises must establish work permit procedures, safety regulations for such operations, safety measures, and emergency response plans for personnel entering confined spaces to work. They should also clarify the responsibilities of those in charge of the operation, the workers involved, and the supervisors, in order to prevent similar accidents from occurring again. (III) Enterprises should strengthen training in risk management and emergency response skills, so as to raise the risk awareness and self-rescue capabilities of workers. In the event of an emergency, workers must be made aware of the potential hazards associated with their work and the possible consequences of those hazards; they should also be familiar with preventive measures as well as methods for self-rescue and mutual rescue. This is necessary to prevent workers from taking risky actions or attempting rescue efforts blindly when the hazards are not clear or when the protective measures are unreliable, thereby avoiding accidents and further increases in casualties. (IV) Enterprises should strengthen safety production training for their employees, ensuring that they possess the necessary knowledge in this area, are familiar with and comply with relevant safety regulations and operating procedures, and have proficient skills in safe operation for their specific roles. (5) ** and relevant departments shall, in accordance with the law, strengthen supervision and management over production and business entities, urge enterprises to continuously improve their safety management, clarify their responsibilities as responsible parties, eliminate potential accident hazards, and ensure safe production.