Résumé : |
The U.S. leather tanning and finishing industry converts about 175,000 tons of collagen each year in making leather. However, an estimated 60,000 to 70,000 tons of this collagen is not converted into consumer leather goods; this portion becomes offal products such as chrome-in-the blue trimmings and shavings, and buffing dust and trimmings from crust and finished leather at tanneries or leather products manufacturing plants. Fiber uses ( e.g., leatherboard ), glue and feed and fertilizer utilize a significant share of this offal tanned collagen. However, a growing share is disposed of in landfill sites which are becoming increasingly costly and difficult to secure. New uses for this tanned collagen being disposed of at landfills are therefore needed. This paper will be a status report on the developmental efforts. Energy and chromium recovery by incineration or pyrolysis are potential procedures. Chromium recovery is especially desirable since sources for U.S. chromite ores are primarily foreign. Since about 17 percent of the total U.S. demand for sodium dichromate is used by the tanning industry, recovery of the underutilized chromium would lessen our ore import level as weel as avoid landfill utilization. The value of recovering the energy would depend on the establishment of a more direct relationship to the needs of the industry. This paper will analyze techno-economic limitations which must be resolved before these potential resource recovery concepts can become commercial. |