Press release: Technical cause analysis is complete: chemical reaction in tank caused pressure to build-up

On Friday 26th February there was an incident involving a tanker lorry on Indaver's site in Antwerp. Following the incident a thorough cause analysis was carried out in collaboration with a number of experts and in close consultation with the customer. The technical investigation has now been completed. The incident occurred due to a chemical reaction, known as a "runaway" reaction in the tank. Thanks in part to the effective safety procedures no injuries were sustained during the incident.

Safety procedures were observed correctly

The reaction occurred in a tanker containing liquid waste which is supplied to the rotary kiln incinerator via a direct feed line. It involved a waste product from a distillation process. The tanker was customised for the supply of this specific waste stream using direct injection to the rotary kiln.  The waste product was heated up so that it could be supplied to the oven. All of the safety procedures were followed in treating the waste: the tanker was under nitrogen inertisation to prevent contact with oxygen and the tanker had been earthed correctly.  

The self accelerating decomposition of the waste created a build up of pressure.

During the feeding process, the waste in the tanker had reached a temperature at which the product started to decompose spontaneously (SADT or self accelerating decomposition temperature). Energy was released during this process. This release of energy further increased the rate of the chemical reaction. As more of the product began to decompose, the pressure built up. The safety systems for the direct feed line and the tanker itself were activated (or worked as designed?), but by that time the reaction and further pressure build-up could no longer be stopped. The high pressure split the tanker open and a combustible cloud of gas escaped and caught fire high in the air. The impact also caused tankers that were parked nearby to catch fire. This subsequent fire was brought under control within two hours.  The smoke dispersed quickly at a great height; and the emergency services in the surrounding areas did not measure any hazardous concentrations at ground level.

Prevention in future

A safe work environment is Indaver's priority, both for the safety of our own staff and the areas immediately surrounding our plants. Indaver is therefore carrying out a thorough safety review of all direct feed lines before putting them back into operation. We are also working with all customers who deliver waste products for thermal treatment via these direct feed lines to carry out a thorough and more detailed analysis of the relevant parameters of their specific waste products and the chosen treatment method. 

Clean-up of the incident zone and restart activities

Significant progress has been made in the clean-up of the incident zone. The physicochemical activities and the landfill site were ready to be put back into operation as early as the 29th of February. On the 5th of March, one of the thermal treatment plants was also put back into operation albeit with the exception of the direct feed lines. The repairs to the two other thermal treatment plants on the site will take another few weeks to complete. These plants suffered damage to their electrical circuits.

More information 

Inge Baertsoen, communications manager, 0497 970570




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