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Tackling hazardous substances with chemical cleaning technology

    • Ammonia and hexavalent chromium – these were the hazardous substances that came to light when a cooling/air conditioning system was being replaced at a federal agency. What had at first appeared to be an uncomplicated project became a case for the specialists at BUCHEN-ICS.

      This cooling/air conditioning system had been installed into the walls and floors throughout the federal agency’s office building including its employees’ workplaces. The specialist firm commissioned to carry out the project had already begun its dismantling work when they discovered that the liquid in the system contained hazardous substances. As a result, Cologne-based BUCHEN-ICS, the Group’s chemical cleaning specialists, were called in to help. They soon realised that they were facing a tricky mixture: an ammonia solution mixed with a corrosion control substance containing hexavalent chromium.

    BUCHEN-ICS chose a chemical cleaning process to rinse out the system that neutralised the ammonia and transformed the toxic hexavalent chromium into safe chromium III. One of the main challenges here was the fact that the system had already been partially dismantled by the specialist firm. Normally, potentially dangerous substances are removed from systems like these while they are still fully intact. In this case, however, some of the pipelines had been separated and the system’s pump disconnected from the electricity supply. The hazmat experts had to tackle the system and the problem section by section. Every pipe tap, collector and heat exchanger had to be individually filled with the cleaning media using an external pump and then emptied. BUCHEN-ICS needed around six weeks to complete this complex project. As soon as they were ready, the old system was able to be taken apart.

    • BUCHEN-ICS’ team of chemical cleaning specialists in Cologne performed a similar task when they removed hazardous substances from and chemically cleaned two wind tunnels at Ford’s development centre

      Read about the project here

    Removing hazardous substances using a multi-stage process

    Ammonia has a corrosive effect and can explode if it comes into contact with air. Chromium hexavalent compounds are contact allergens and have toxic properties. Handling both substances is a challenge – and hexavalent chromium must be managed with particular care. BUCHEN-ICS deployed a multi-stage process to ensure that the hazardous substances were removed from the federal agency’s cooling/air conditioning system in a safe and environmentally compatible way.

Step 1: Neutralising the ammonia

To begin with, BUCHEN-ICS filled the system section by section with an acidic solution, which was then removed using pumps and transported in a container. There, too, an acidic solution was added again. Throughout the whole of the process, the various neutralisation procedures required around 30 tonnes of rinsing water with a pH value that was practically neutral. BUCHEN UmweltService was responsible for managing the used rinsing water.

Step 2: Transforming hexavalent chromium into safe chromium III

To transform the hexavalent chromium, the system was once again filled section by section – this time with a solution that contained a small amount of a specially prepared reducing agent. The solution was left in the system’s sections for a certain period of time. It was then pumped out, adjusted to a slightly acidic pH value using sulphuric acid and then mixed with a new dose of reducing agent so it could be reused for the next section of the cooling/air conditioning system. New solutions had to be deployed several times and BUCHEN-ICS pumped the used solutions into a special container. Samples were taken to check the chromate content. At no point was hexavalent chromium detected again.

Step 3: Rinsing out the cooling/air conditioning system with water

Finally, after completing this work, BUCHEN-ICS used water to rinse out all of the system’s sections it had treated. Just to be on the safe side, checks were carried out again to monitor the chromate content and once again no hexavalent chromium was detected. The removal of the hazardous substances from the old system was completed as soon as the rinsing water had been removed. The system could now be safely dismantled and taken away.

BUCHEN-ICS deployed various types of equipment including a standard chemical pump unit with a pump capacity of 100t/h. Moreover, a vacuum unit was on hand as a precaution which would have been used if the ammonia solution had leaked out

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