【Accident Case Analysis】03 The “2·16” Poisoning Incident at Baiyin Lefu Chemical Co., Ltd. (Case Analysis)

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I. Accident Investigation and Analysis (I) Overview of the Accident 1. Introduction to the Accident On February 16, 2012, an hydrogen sulfide gas poisoning accident occurred at Baiyin Lefu Chemical Co., Ltd. in Baiyin District, resulting in 3 deaths and direct economic losses of 70,000 yuan. 2. Causes of the accident: (1) Direct cause – Hydrogen sulfide gas generated by the reaction between cresol and phosphorus pentasulfide when heated in the reactor leaked from the reactor’s shaft, resulting in the workers’ poisoning and death. (2) Indirect causes: ① Workers do not fully understand the effectiveness of filter-type gas masks; working in toxic environments for extended periods causes the masks to become ineffective and lose their protective function. ②When constructing the black powder production facility at this plant, the required procedures for simultaneous implementation of various construction aspects were not followed, and the safety facilities were not approved after undergoing proper inspection. ③The factory operates at night, which provides a high degree of concealment, allowing it to carry out its illegal production without being detected in time by the regulatory authorities, thus evading oversight. (II) Basic Information 1. Information on the entity involved in the accident: Baiyin Lefu Chemical Co., Ltd. was registered with the Baiyin City Administration for Industry and Commerce in July 2005. It is located to the east of the Brick and Tile Factory in Wangxian Town, Baiyin District; its legal representative is Mr. Da, and the registered capital is 1.02 million yuan. The company’s business scope includes the production and sales of chemical products, as well as the wholesale and retail of mineral products, metal materials, and mechanical and electrical products. After the change in 2010, the business scope became the production and sales of chemical products (excluding hazardous chemicals) ； Wholesale and retail of mineral products (excluding special mineral products), metal materials (excluding precious metals), mechanical equipment, and electronic products. (III) Course of the accident: Description of the date and time – On the morning of February 16, Xing, an employee of the Copper Division of Baiyin Non-ferrous Metals Group Co., Ltd., went to see Da, the legal representative of Baiyin Lefu Chemical Co., Ltd., for some matter. He called Da and Liu (Da’s spouse) several times, but was unable to get through in each case. At 11:00 on February 16, Xing went straight to Lefu Company to look for Da. After searching around, he found that Da, Liu, and their son were all lying on the operation platform in the workshop (Da and Liu were wearing gas masks). Seeing that they didn’t move, Xing called the emergency number “120” and “119” to request help. After the firefighters from the Baiyin City Fire Brigade arrived, they carried the three people out of the workshop. According to the diagnosis by the doctors from the 120 emergency service at Baiyin City’s Second People’s Hospital, Da and the other two had been dead for over 10 hours. (IV) Accident losses: This poisoning incident resulted in 3 deaths and direct economic losses of 70,000 yuan. (V) Analysis of the accident causes: Through investigation and evidence collection, it was found that Baiyin Lefu Chemical Co., Ltd. produced Reagent No. 25, a chemical used in mineral processing, on an intermittent basis from September 2005 to September 2009, based on orders received. Production took place every one or two months, with each production cycle lasting around 5 days, during which time approximately 10 tons of this reagent were manufactured. Pilot production takes place during the day, while full-scale production is carried out at night once the production parameters are established. From June 2009 to November 2011, production was halted due to a lack of orders; after receiving orders in December 2011, phosphorus pentasulfide and tricresol were purchased, and an accident occurred during production on February 16, 2012. 1. Analysis of the direct cause: Black Agent No. 25 is a mineral processing reagent. When trimeric cresol and phosphorus pentasulfide are heated to a certain temperature in a reaction vessel, they react to produce Black Powder No. 25, with hydrogen sulfide gas being released in the process. The reaction equation is as follows: 4C7H8O + P2S5 = 2(C7H7O)2PSH + H2S↑. To prevent poisoning by hydrogen sulfide gas, the production of Black Powder No. 25 must take place in a sealed reaction vessel under negative pressure. The hydrogen sulfide gas generated within the reaction vessel is drawn through negative-pressure pipelines to an alkaline solution tank (a hydrogen sulfide absorption system) where it is absorbed. The reaction equation for this process is as follows: H2S + 2NaOH = Na2S + 2H2O. However, in Lefu Company’s production facility for Black Powder No. 25, the water-ring vacuum pumps have become corroded and damaged due to long-term disuse, and thus cannot be used; they are completely disconnected from the production system. Da and Liu wore filtering gas masks and carried out their work in a pressurized environment, which led to their death as a result of hydrogen sulfide gas leaking from the stirring shaft head of the reactor (at the seal where the packing was installed). Their son, upon discovering this, tried to carry out rescue efforts without wearing any protective equipment, and thus he too died from poisoning. 2. Analysis of indirect causes: ① Workers do not fully understand the effectiveness of filter-type gas masks; working in toxic environments for extended periods causes the masks to become ineffective and lose their protective function. ②When constructing the black powder production facility at this plant, the required procedures for simultaneous implementation of various construction aspects were not followed, and the safety facilities were not approved after undergoing proper inspection. ③The factory operates at night, which provides a high degree of concealment, allowing it to carry out its illegal production without being detected in time by the regulatory authorities, thus evading oversight. II. Reflections and Recommendations This accident highlights the serious safety issues existing in small workshops and small and medium-sized enterprises, which require close attention. 1. Small workshops and small and medium-sized enterprises generally suffer from serious problems such as insufficient safety facilities, weak management, low safety awareness among employees, and poor emergency response capabilities; in the event of an accident, attempts at rescue are made blindly, which leads to the escalation of the situation. 2. The Baiyin District must earnestly learn from the lessons of these accidents and apply those lessons to similar situations. It is necessary to conduct a thorough analysis of the prominent problems, safety supervision gaps, and weak points that emerged in the poisoning incident at Baiyin Lefu Chemical Co., Ltd. on February 16th, and to take effective measures to strengthen oversight of work related to safe production as well as efforts to crack down on illegal activities. More effort should be invested in implementing the requirements of ** and the province’s “four musts” as well as the “six sets of actions.” In accordance with laws, regulations, and policies, illegal construction and production activities must be firmly eliminated. 3. Relevant towns, sub-districts, and departments are required to strictly fulfill their responsibilities for safety production supervision and management. They must conduct thorough inspections of enterprises within their jurisdictions, and whenever an enterprise is found to be operating in violation of safety requirements, it must be dealt with immediately. 4. Relevant departments and units shall, in accordance with the requirements of laws, regulations, rules, and standards related to work safety, strengthen cooperation and coordinate closely to create a joint effort to crack down on illegal and irregular activities. They should focus on addressing the fundamental and root-level issues existing in enterprises’ construction projects and production processes, urge enterprises to assume their primary responsibility for safety management, and prevent similar accidents from occurring. At the same time, efforts should be made to promote laws and regulations on work safety, so as to create a positive social atmosphere focused on cracking down on illegal and irregular activities across society.