Treating waste containing mercury in the rotary drum
The company Dela GmbH has operated a rotary drum distillation system at its site in Essen since 1991 for the environmentally compatible treatment of waste containing mercury such as e.g. mineral industrial slurries, slurries from the movement of natural gas, active carbons, catalysts, button cells or contaminated earth.
The rotary drum distillation system serves to remove and recover the mercury in the waste by means of evaporation and the recycling of the then mercury-free product (e.g. glass, iron and non-ferrous metals, zeolites). Any pollutants or hydrocarbons and sulphur are removed in the treatment process; mercury is returned to the economic cycle. The system, which has been approved according to the Federal Immission Control Act (BimSchG), is operated continuously (3-shift operation) and is designed to treat up to 400 kilograms of waste every hour.
Brief profile of the system
| Special aspect | Process with ideal heat transfer, emission-free operation by means of under-pressure |
| Annual capacity | Approx. 3,500 |
| Throughput | 400 kilograms per hour |
| Process | Under-pressure distillation procedure |
| Exhaust air | Cleaning via hot gas dust filters, two active carbon filter systems |
| Input | Industrial slurries containing mercury, active carbons, catalysts, button cells, contaminated earth |
| Output | Mercury condensate, water, hydrocarbons, residual substances removed from pollutants for recycling / disposal |
Procedure
The waste that is to be treated is fed evenly from a feed hopper via a dosage system to the rotary drum. Waste that needs to be treated in the rotary drum distillation system must be free-flowing and conveyable. The waste is treated in the rotary drum distillation system at temperatures of up to max. 800°C. The materials used are moved evenly through the rotary drum thanks to the rotary movement of the drum. The mercury in the waste is evaporated by heating the waste up to temperatures over 356 °C. The required holding time of the waste in the rotary drum depends on the materials used and usually lies between 0.5-1.5 h. The treatment is carried out at under-pressure to guarantee that the system operates safely. If necessary, nitrogen is added to make the atmosphere in the rotary drum inert.
The stream of exhaust air flows to two gas scrubbers via a hot gas dust filter in which the mercury, and water and hydrocarbons condense. The stream of exhaust air that is cleaned in this manner is then fed to an active carbon filter system for final cleaning.
The recovered mercury is then purified to a defined level in a final treatment step in the pure distillation stage and then filled in transportation-approved steel cylinders for distribution.
