‘Dust explosion’: Telangana govt informs high court what likely caused Sigachi factory blast

The report said that a detailed analysis of the sequence of events leading to the explosion and fire is to be worked out based on several documents such as process chemistry, process flow information (PFD and P&IDs), equipment design and diagrams, past accident and near miss data, operability hazards, previous safety assessment reports (safety audits, PHA, risk assessment), occupational safety & health (OSH) assessments, site plan, floor plan, structural integrity assessments etc.

It added that an accident culminates from a sequence of (long or short) failures, absence of adequate process control equipment, integrated safety interlock systems, poor choice of equipment, lack of preventive maintenance, poor safety culture, inadequate technical skills of the employed manpower and human errors.

“M/s Sigachi Industries Ltd. process for Micro Crystalline Cellulose (MCC) and its operations had an inherent danger of dust explosion hazard. Accidents involving Cellulose dust has been reported (Cellulose dust, Rosenberg, Germany, 2018). The site visit and subsequent inquiry and Investigation with the workers revealed the occurrence of multiple explosions followed by severe fire which spread to adjutant buildings,” it said.

“The blast and fire caused implosions of the major portion of the building with dark smoke, dust and projectiles (building materials and part of equipment). Thus, the dust explosion was the final culminating event in the confined environment, probably due to ignition of dust cloud within any of the unit operations or equipment,” it further stated, adding that the impact of the dust explosion’s shock waves lifted several equipment placed congestedly in confinement.

The report has also suggested 23 technical recommendations to be implemented across all chemical process industries across the state.

11 violations under Factories Act

Meanwhile, the inspection report of the deputy chief inspector of the Factories Department listed 11 violations under the Factories Act. The violations range from failure to “provide explosion relief panel of adequate size and capacity for the spray dryer to ensure release of excessive pressure in the spray dryer” and “provide effective audio and visual alarm system to warn the temperature rise inside the spray dryer chamber above predetermined safe limits” to failure “to carry out prior dust hazard analysis of Micro Crystalline Cellulose Powder (MCCP) before starting using spray drier and other powder processing equipment” and “prevent overcrowding of the employees in one building”.

The report stated: “Consequently [to these violations] on 30.6.2025 at about 9.25AM, while carrying on the manufacturing of Micro Crystalline Cellulose Powder (MCCP) through acid hydrolysis of cellulose followed by neutralization and spray drying involving atomizing an MCC slurry in drying chamber of spray drier where hot air of temperature at about 200°C to 205°C is passed, an excessive pressure is built up in the spray drier due to formation of explosive and flammable mixture resulting in dust explosion and fire in the spray drier and subsequent secondary dust explosion and fire took place in the powder processing area causing complete collapse of RCC G+1 building which accommodates production block having Spray Drier (1 No), Fluid bed driers (5 Nos), Blenders (2 Nos) & Spin Splash Dryers (1 No) etc., on the ground floor and Q.C. in the first floor and the following workers working in these areas got trapped and sustained serious injuries and fatalities.”