At around 6:30 a.m., an explosion occurred at the foot of the elevator of a port-based silo in the process of being loaded. This explosion resulted in two more explosions. An explosion occurred in the dust collector filter as the result of incandescent particles being sucked in. Another occurred in the upper floors of the handling tower. The operating technicians heard the explosion but were unable to pinpoint the origin. A technician loading ships raised the alarm after the supply of grain had stopped. The operating technicians then noticed a defect in the current-based safety system. They cleared the fault without performing a verification inspection and merely put the elevator back into operation. As the elevator did not restart, they decided to go inspect the installation and noticed a burning smell and several plates that had been lifted out of place, and the access door to the handling equipment on the ground floor was open. A few sleeves were burnt. The opening of the vents on the dust collection system limited the excess pressure on the filter. The silo structures were not affected.

The firefighters, having been alerted by a local resident, proceeded to the site. The following measures were implemented: ship loading operations were halted, the base of the elevator was cooled down with hoses as a preventive measure, and the elevator was emptied.

The accident was caused by the collapse of the strap pulley. This then caused the drum to tip which, as it continued to rotate, rubbed against the sheeting causing it to melt. As the rotation controller was located on the other pulley shaft which was still moving, no fault detection was performed. The microcracks that caused the shaft to break formed as a result of the considerable forces exerted on the drums during successive adjustments made to the strap tension. The current design of the elevator does not allow a visual inspection to be conducted on shaft ends without extensive work. In addition, considering how the operating technicians had reacted, the operating procedures and staff training could be improved.

The operator had a study conducted that determined that only 1 minute was required for the temperature to rise to the point where the dust accumulated at the bottom of the lift would ignite. To prevent new accidents from occurring, the operator put the following measures into practice:

• an additional rotation controller opposite the existing controller at the top and base of the elevator;
• temperature sensors for bearings and on the sheetmetal in areas at risk of friction;
• acknowledgement of safety defects on a housing allowing the installation to be immediately shut down;
• power converter on the motor to limit the stresses on the various mechanical elements, particularly during start-up.