Contaminated silver from the UIC, Inc. Total Carbon Unit’s combustion tubes can be reclaimed. There is generally a 10% loss using the procedure outlined below. Special care must be exercised since the procedure uses both acid and explosive hydrogen gas.
- Remove the used silver from the combustion tube. The silver usually cannot be removed without breaking the combustion tube.
- Break up the silver plug with a wood rasp or an appropriate grinder.
- Wash the silver with 10% nitric acid.
- Rinse the silver thoroughly with deionized (or distilled) water.
- Dry the washed silver at 110˚C.
- Place the silver in a clean combustion tube. DO NOT PACK TIGHTLY.
- Pass hydrogen gas through the tube with a flow rate of 20-30cc/min. Bubble the exit gas through water to remove any acid gases that may form.
- Heat the combustion tube to 800 – 850˚C for two (2) hours. Keep the H2 flow on.
- Remove the exit gas water bubbler, cool the furnace, stop the H2 flow, and remove the reclaimed silver.