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Historical hazardous chemical accidents that occurred in June (I): Domestic accidents. The “6·5” explosion and fire incident at Jinyu Petrochemical Co., Ltd. in Linyi, Shandong Province. On June 5, 2017, a tank truck transporting liquefied petroleum gas at the loading and unloading area of Jinyu Petrochemical Co., Ltd. in Linyi City, Shandong Province, experienced a leak, explosion, and fire during the unloading process, resulting in 10 deaths and 9 injuries. The direct cause of the accident was that when the liquefied gas truck was unloading at the unloading platform, the coupling of the quick connector was not secured properly, resulting in a separation at the joint and a massive leakage of liquefied gas. This gas mixed with air to form an explosive mixture, which exploded upon encountering an ignition source. The \"6·15\" fire accident at Shijiazhuang Refining and Chemical Plant in Hebei On June 15, 2016, a fire broke out in the absorption tower of the flue gas desulfurization and denitrification facility at Sinopec Shijiazhuang Refining and Chemical Branch in Shijiazhuang City, Hebei Province; this incident resulted in 4 deaths. The direct cause of the accident was that, during the anti-corrosion welding work on the top of the chimney, inadequate isolation measures led to welding slag falling from the gaps onto the mist remover layer, causing the mist remover made of polypropylene to catch fire. Hot smoke was then discharged through the chimney, resulting in the death of the workers due to heat exposure and poisoning asphyxiation. The major explosion and fire accident at the triphenyl tank area of Dalian Petrochemical Branch of China National Petroleum Corporation on June 2, 2013: On June 2, 2013, an explosion and fire broke out at the triphenyl tank area of the First Combined Workshop of Dalian Petrochemical Branch of China National Petroleum Corporation during welding operations, resulting in 4 deaths and direct economic losses of 6.97 million yuan. The direct cause of the accident was that contractor workers carried out illegal gas cutting operations on the roof of a miscellaneous tank in the triphenyl tank area of the First Combined Workshop; the cutting flame ignited flammable and explosive gases such as toluene that had leaked, and the backfire entered the tank, causing it to explode. This in turn led to the successive explosion and ignition of three other tanks in the vicinity. The “6·29” crude oil tank explosion incident at CNPC Liaoyang Petrochemical Branch On June 29, 2010, an explosion occurred in a crude oil tank at the crude oil transfer station of CNPC Liaoyang Petrochemical Branch’s refinery during tank cleaning operations. This incident resulted in the death of 5 workers inside the tank and injuries to 5 others, with direct economic losses amounting to 1.5 million yuan. The direct cause of the accident was that, during the on-site tank cleaning operation at a 30,000-cubic-meter crude oil tank at the crude oil transfer station, the oil and gas generated mixed with air, creating an explosive gas environment. Sparks were produced either by non-explosion-proof lighting fixtures that flickered or sparked, or by metal cleaning tools used in the operation hitting the bottom of the tank, which led to the explosion and fire incident. The \"6·28\" fire accident at the Lanzhou Petrochemical Refinery in Gansu On June 28, 2006, a leak at the cover of a condenser in the refinery’s 400,000 tons per year gas fractionation unit triggered a fire. One corporate firefighter lost their life and 10 others were injured during the fire fight. The direct cause of the accident was that the maintenance personnel failed to remove the plastic film wrapped around the wave-shaped gasket when installing the condenser cover. After the vehicle was started, leakage occurred at the seal of the condenser cover; the high-speed spray of liquid hydrocarbons generated static electricity on the wave-shaped gasket covered with plastic film, which in turn ignited the leaking liquid hydrocarbons and caused a fire. The serious fire and explosion incident at Henan Kaifeng Xumei Biotechnology Co., Ltd. in the fine chemicals industry: On June 26, 2019, a fire and explosion occurred in the natural fragrance extraction workshop of Kaifeng Xumei Company, resulting in 7 deaths and 4 injuries, with direct economic losses of over 20 million yuan. The direct cause of the accident was that the worker heated the ethanol and red dates inside the tank to carry out the extraction process for jujube tincture without opening the vacuum-breaking valve at the top of Extraction Tank No. 1, nor the valve at the bottom of the condensation receiving tank. This led to overpressure in the tank, causing the discharge lid to burst open; large amounts of hot ethanol liquid spilled out of the tank and were ignited by static electricity. The vaporized ethanol gas exploded when it came into contact with an open flame, and the ethanol and ethanol-containing extracts stored near the plant facilities further fueled the spread of the fire. The \"6·18\" explosion accident at Chai Gang Xing Fa Furfural Co., Ltd. in Nong’an County, Jilin Province On June 18, 2018, Chai Gang Xing Fa Furfural Co., Ltd. in Nong’an County, Jilin Province, carried out illegal production during a period when it should have been shut down; an explosion occurred in Hydrolysis Reactor No. 10 in the hydrolysis workshop, resulting in 3 deaths, 3 injuries, and the collapse of the workshop building. The direct cause of the accident was illegal production during the company’s shutdown, a failed safety valve, and an overpressure explosion in the hydrolysis reactor. The \"6·9\" deflagration accident at Zhejiang Shaoxing Linjiang Chemical Co., Ltd. On June 9, 2017, Zhejiang Linjiang Chemical Co., Ltd. experienced a deflagration accident while carrying out pilot-scale production of a new pesticide, resulting in 3 deaths and 1 injury. The direct cause of the accident was that the new product being tested by Linjiang Chemical involved an unstable intermediate, which decomposes slowly at temperatures below 40°C; the decomposition rate increases as the temperature rises, and it decomposes rapidly at 130°C. Without knowledge of the physicochemical properties of the new products and intermediates, as well as the associated reaction risks, Linjiang Chemical used obsolete industrial equipment to carry out pilot tests for these new products. During the steam distillation process in the reaction vessels, steam heating in the jacket caused localized high temperatures; this led to extensive decomposition of the intermediates, resulting in a sharp increase in temperature and pressure inside the reaction vessels, and ultimately an explosion. On June 26, 1996, an explosion occurred at Tianjin Jinxi Dahua Chemical Plant. The incident resulted in 19 deaths, 14 injuries, and direct economic losses exceeding 1.2 million yuan. The direct cause of the accident was as follows: in the days prior to the incident, there was persistent high temperature. The factory roof was made of asbestos sheets, which offered poor thermal insulation; this high temperature facilitated the combustion process of the oxidizer. The strong oxidizer sodium chlorate underwent an exothermic oxidation reaction with organic substances, and the resulting heat further accelerated this oxidation reaction. This cycle ultimately led to the combustion of the organic substances and combustibles. During the fire fighting process, the acidic water sprayed onto sodium chlorate (a strong oxidizing agent) accelerated the oxidative decomposition of the oxidizing agent, resulting in the production of large amounts of chloric acid. The high-temperature and high-pressure gases generated by the explosion of the mixture of chloric acid and sodium chlorate caused the explosion of 2,4-dichloroaniline. The serious asphyxiation accident at Shandong Weifang Huahao Agrochemical Co., Ltd. on June 5: On June 5, 2016, an asphyxiation accident occurred in the water-soluble fertilizer production workshop of Shandong Weifang Huahao Agrochemical Co., Ltd., resulting in 3 deaths and direct economic losses of around 2.4 million yuan. The direct cause of the accident was that the operator started the pump in order to transfer the material in the tank to subsequent equipment, but found that it was not possible to extract the material. Without checking the oxygen and toxic gas concentrations or wearing any personal protective equipment, the operator went into the tank to investigate the situation, and died as a result of oxygen deprivation ； Two other workers entered the tank without wearing personal protective equipment in an attempt to carry out rescue efforts, and they also died from asphyxiation due to lack of oxygen, which exacerbated the consequences of the accident. The “6·28” explosion and fire accident at Yidong Jiuding Chemical Company in Ordos, Inner Mongolia On June 28, 2015, an explosion and fire broke out at Yidong Jiuding Chemical Co., Ltd. in Ordos, Inner Mongolia, resulting in 3 deaths and 6 people suffering minor injuries. The direct cause of the accident was that, due to quality issues with the three-gas heat exchanger, there were existing through cracks at the fillet welds of the desulfurization gas inlet head, which had been repaired and welded four times prior; these cracks led to low-stress brittle fracture, resulting in the sudden release of desulfurization gas. Due to the high hydrogen content in the desulfurization gas, a hydrogen explosion occurred at the moment of leakage, resulting in injuries and deaths among the personnel who were carrying out maintenance and insulation work in the vicinity. The \"6·12\" hydrogen sulfide poisoning incident at Anning Qitian Fertilizer Co., Ltd. in Kunming On June 12, 2008, an hydrogen sulfide poisoning accident occurred at Anning Qitian Fertilizer Co., Ltd. in Kunming, Yunnan Province, during the pilot production of arsenic-removed refined phosphoric acid; this incident resulted in 6 deaths and 29 people being poisoned. The direct cause of the accident was that while adding a sodium sulfide aqueous solution to the phosphoric acid tank, the operator found that the bottom valve could not be closed. As a result, the sodium sulfide aqueous solution continued to flow into the tank, causing an excessive amount of sodium sulfide to accumulate there. The large quantity of hydrogen sulfide gas generated escaped from the upper part of the unsealed tank, leading to poisoning of some of the workers on site as well as those who came to provide assistance. The asphyxiation accident at Shixing Pharmaceutical and Chemical Company in Huludao, Liaoning Province: On June 20, 2018, an asphyxiation accident occurred in a confined space at Shixing Pharmaceutical and Chemical Co., Ltd. in Huludao City, Liaoning Province, resulting in 3 deaths. The direct cause of the accident was that, without properly purging the 1# p-chloroaniline crystallization tank that was in a shut-down state – a tank that had been taken out of use at the end of March 2018 for process-related reasons and had been kept under nitrogen protection at a pressure of 2 kilograms – an operator was sent to carry out cleaning work without first ensuring that the oxygen level was within acceptable limits. As a result, this operator encountered danger; two other people attempted rescue blindly, and all three died as a result of nitrogen asphyxiation. The \"6·11\" poisoning incident in the chlor-chemical production section of the Pesticide Branch of Henan Xinyang Chemical Complex. On June 11, 1994, a poisoning accident occurred in the chlor-chemical production section of the Pesticide Branch at Henan Xinyang Chemical Complex, resulting in 3 deaths and 8 people being poisoned. The direct cause of the accident was a blockage at the bottom of washing tank No. 2 in the chlorination section of the Methyl 1605 workshop in the pesticide subsidiary plant; as a result, the tank was shut down and its upper manhole was opened for maintenance. Three workers were on duty, one of them wore a filtered gas mask while working inside the tank, with the team leader overseeing from outside. As soon as the workers entered the tank, they fainted; the team leader who peered inside also fainted. Another worker noticed this and called for help, and workers from other shifts joined in the rescue efforts. As a result, 11 people inside and outside the tank were poisoned, 3 of whom died despite attempts to save them. The “6·27” explosion accident at Huazhi Coal and Coke Company in Wuhai, Inner Mongolia, in the coal chemical industry: On June 27, 2017, an explosion occurred in the desulfurization section of the chemical production workshop at Huazhi Coal and Coke Co., Ltd. in Wuhai City, Inner Mongolia Province, resulting in 3 deaths. The direct cause of the accident was that the solution in the desulfurization solution circulation tank came from the regeneration tower; its main component was ammonia water, and it might also contain other flammable volatile gases. Ammonia gas or other such flammable volatile gases formed an explosive mixture with the air inhaled. The company’s maintenance team installed pipes on the top of the desulfurization solution circulation tank without obtaining a hot work permit; the ignition sources generated by cutting or welding caused an explosion of the explosive mixture inside the tank, resulting in 3 deaths at the top of the tank. The “6·12” hydrogen sulfide poisoning accident at Taizhou Fengrun Biochemistry Company in Zhejiang Province On June 12, 2009, a hydrogen sulfide poisoning accident occurred at Taizhou Fengrun Biochemistry Co., Ltd. in Zhejiang Province, resulting in 3 deaths and 2 people being poisoned. The direct cause of the accident was that a construction worker went down to the bottom of an underground pile hole at a depth of about 10 meters to carry out work; he was poisoned and collapsed due to high levels of hydrogen sulfide. Subsequently, four other people tried to rescue him without wearing any protective equipment, and they too were poisoned and collapsed one after another. (II) Foreign accidents: Explosion at the refinery of Energy Solutions Company on the U.S. East Coast On June 21, 2019, an explosion occurred in the alkyl fluoride production unit at the refinery of Energy Solutions Company located on the U.S. East Coast in Philadelphia, resulting in minor injuries to 5 people. According to the American NBC television network, the fire could be seen from miles away, and the thick smoke from the explosion covered most of downtown Philadelphia and southern Philadelphia. Cause of the accident: A bend in the piping circuit system of the alkyl fluoride production unit became thin due to corrosion, which led to its rupture; propane in the pipeline leaked, resulting in a fire and explosion. Fire and explosion at a gas plant in Pascoagula, Mississippi, USA: On June 27, 2016, there was a severe leak of methane, ethane, propane, and other hydrocarbons at a gas plant in Pascoagula, Mississippi, USA. This led to a fire and explosion, which resulted in the closure of the plant for over 6 months and the evacuation of residents living in the surrounding area. Cause of the accident: Failure of the aluminum brazed heat exchanger (BAHX) may have been caused by thermal fatigue. There is no reliable process to ensure the mechanical integrity of the heat exchanger, which leads to equipment failures, leaks of hydrocarbon materials, and ultimately fires and explosions. Explosion of the methanol distillation tower at the Chiba plant of Nippon Shishi Co., Ltd. On June 26, 1991, at the Chiba plant of Nippon Shishi Co., Ltd., during the production of a new type of surfactant called “α-sulfonated fatty acid esters,” a small amount of methyl peroxide was generated as a result of the reaction between methanol and hydrogen peroxide. When the distillation tower stopped operating, the concentration of this substance locally increased from 0.1% to several percent, which led to heating and ultimately an explosion in the tower. This accident resulted in 2 deaths and 13 injuries; the tower and surrounding facilities were severely damaged, and explosion debris and shock waves destroyed 319 areas within the factory. Cause of the accident: (1) During the bleaching process, residual anhydrous sulfuric acid reacted with the added methanol to form methyl sulfate; methyl sulfate can only react with hydrogen peroxide to produce methyl peroxides under acidic conditions. Methyl peroxides are relatively stable in weakly acidic aqueous solutions and hardly decompose, but they are unstable in neutral and alkaline solutions, with their decomposition accelerating as the temperature rises ； (2) Under normal operation (with a reflux ratio of 5), the maximum concentration of methyl peroxide does not exceed a few percent; whereas during \"full reflux operation,\" the concentration of methyl peroxide is increased to several tens of percent ； (3) On the day of the accident, the pH meter in the neutralization section malfunctioned, resulting in a reduced amount of caustic soda used for neutralization and making the solution acidic. As a result, methyl peroxide was not easily decomposed, causing its accumulation in the tower to increase from 10–20 kg under normal conditions to 30–40 kg ； (4) During the “incineration operation,” the concentration of methyl peroxide in the liquid phase is higher than that during the “full reflux operation.” Additionally, as the reflux from the top of the tower stops, no methanol solution is circulated back into the tower for cooling, resulting in the heat generation rate exceeding the heat dissipation rate and causing the distillation tower’s temperature to rise rapidly ； Coupled with the local heating during the burning process, as well as the friction and collisions between the movable parts inside the tower, the exothermic decomposition reaction of methyl peroxides gets out of control, ultimately leading to an explosion.