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Metal Processing

Ammonia Reduction for Heat Treat Furnace Atmospheres. 1997

  TURI Technical Report No. 43. Heat treating is essential to various metal forming processes, keeping the metal soft enough to be twisted, stamped, bent, rolled, etc. The furnaces at General Findings are used for soldering in addition to heat treatment. Jewelry components are assembled in graphite trays (known as "coals"), and as they pass though the solder furnace components are bonded together (as opposed to each piece being hand-soldered). At elevated temperatures in these furnaces, metals react with air to form oxides. A protective atmosphere must be maintained to achieve the desired bright and clean finish. This atmosphere is achieved by dissociating (splitting) anhydrous ammonia into its basic components: 75% hydrogen, and 25% nitrogen by volume. Successful tests with lower hydrogen levels were performed in-house by diluting the dissociated ammonia ("DA") with nitrogen. Although this project will not decrease anhydrous ammonia consumption below reporting thresholds, the significant reduction in ammonia usage reduces the potential for worker exposure and environmental impact. This project also allows General Findings to plan for an increase in production activity without additional regulatory requirements. Download PDF file (394.40 kB)