Case Ditails

Scenario
Case Name Explosion at a reactor caused due to a temperature rise of a recovery process of hydroxylamine sulfate at a pharmaceutical production plant
Pictograph
Date September 6, 1974
Place Amagasaki, Hyogo, Japan
Location Pharmaceutical factory
Overview In 1974, an explosion occurred at a recovery process of hydroxylamine sulfate from a waste liquid in a pharmaceutical manufacturing plant in Amagasaki, Hyogo. The upper half of the reactor blew off and the ceiling of the building ruptured.
Incident An explosion occurred from an exothermic reaction in a recovery process for waste from a pharmaceutical manufacturing plant. The waste was including mainly methyl isobutyl ketoxime (MIBK oxime), which is obtained from a reaction of adding MIBK to a mixture of hydroxylamine sulfate and a trace of carboxylic acid.
Processing Manufacture
Individual Process Concentration
Process Flow Fig2.Unit process flow 1
Chemical Equation Fig3.Chemical reaction formula
Substance Hydroxylamine sulfate, Fig4
Sulfuric acid, Fig5
Methyl isobutyl ketoxime, Fig6
Type of Accident Explosion
Sequence To recover hydroxylamine sulfate from a waste liquid of a pharmaceutical plant, the waste liquid and dilute sulfuric acid were poured into a reactor and cooled overnight. Next morning, the mixture was concentrated at 70 °C under reduced pressure, and left for 30 minutes at reduced pressure after heating was stopped. The material was jelly-like, so heating was started again. Suddenly, a whistling sound was heard coming from inside, so cooling water was hurriedly fed into the jacket of the reactor, but the material in the reactor exploded. The upper half of the reactor blew off and the ceiling of the building ruptured.
Cause The waste was hydrolyzed with dilute sulfuric acid to MIBK and hydroxylamine sulfate. During concentration under reduced pressure, MIBK oxime in the hydrolysate was assumed to stick to the inner wall of the reactor. By heating after concentration, the temperature of the headspace reached 100 °C, an exothermic reaction resulted in Beckman rearrangement of oxime, and hydroxylamine sulfate was ignited by the high temperature caused by Beckman rearrangement.
Countermeasures The temperature should be kept under 100 °C. A temperature alarm should be mounted at the reactor. If possible, the possibility of the contents sticking to the inner wall of the reactor should be reduced.
Knowledge Comment 1. Keeping the temperature lower than the hazardous level of a specific chemical process.
2. The temperature of the inner wall of a reactor can be higher if it is not covered with a liquid. Paying attention not to leave products sticking to the inner wall is important.
Background The cause of the accident is considered that operators did not know that Beckman rearrangement takes place above 100 °C, or the operation manual failed to pay attention to Beckman rearrangement.
Reason for Adding to DB Example of explosion caused due to temperature raising to a hazardous range
Scenario
Primary Scenario Ignorance, Insufficient Knowledge, Insufficient Study of Reation, Poor Value Perception, Poor Safety Awareness, Insufficient Education/Training, Hydrolysis, Planning and Design, Poor Planning, Unclear Operating Indication, Regular Movement, Careless Movement, Interruption at Halfway, Bad Event, Chemical Phenomenon, Heat Generation/Ignition, Secondary Damage, External Damage, Explosion, Bodily Harm, Injury, Loss to Organization, Economic Loss
Sources Masamitsu Tamura. Masahide Wakakura. Hydroxylamine sulfate explosion. Reaction danger. - Accident cases and analysis - p161(1995)
Number of Injuries 1
Multimedia Files Fig4.Chemical formula
Fig5.Chemical formula
Fig6.Chemical formula
Field Chemicals and Plants
Author YOSHINAGA, Jun (Graduate School of New Frontier Sciences, The University of Tokyo)
TAMURA, Masamitsu (Center for Risk Management and Safety Sciences, Yokohama National University)
Scenario