Process industries generate a number of hazardous waste streams that contain metals bound with organic components. These metals can be quite valuable, if they can be separated from the organic components and then recovered. Combustion has been used successfully to separate these metals from their organic fractions. In the combustion process, waste streams are thermally oxidized at high temperatures. Carbon and Hydrogen are oxidized to Carbon dioxide and water vapor. Metals present in the waste streams are also oxidized. Oxygen is provided by combustion air. Depending on the composition, the waste itself can usually provide heat required for the combustion process. Once the combustion process is complete, the metal oxides(s) must be then separated from the combustion gases. If the combustion process has been carried out at around 1800℉, the gases must be quenched in a water quench system. The metal oxides must then be separated from water for recovery. If the combustion process has been done at a lower temperature, metals recovery can be accomplished by a baghouse. Since the process takes place at a high temperature in an oxidizing atmosphere, special care must be taken in the design of the equipment. Waste injection nozzles must be corrosion and erosion resistant. Refractory materials must take into account the high temperatures, metals present and oxidizing atmosphere. Four examples of projects are provided in this paper. These projects are: waste containing Molybdenum to recover Molybdenum trioxide, Ammonium di-chromate to recover Chromium oxides, waste containing Potassium nitrates to form Potassium carbonate liquor, which was then used as a catalyst, Iodine in the presence of Sulfur dioxide with Iodine recovered as Hydrogen iodide.
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