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Show This SGFB incinerator affords processing advantages that include a pneumatic size classification of the reclaimed grit. In addition, the sloped-grid incinerator design facilitates the removal of any tramp material fed or fusible lumps formed. Under its own Internal R&D program, IGT conducted feasibility tests on the use of fluidized beds for thermal reclamation of blast abrasives. These tests showed that, at fluidization velocities above 3 ft/s and temperatures in the range of 1200 0 to 1500 0 P, both organic contaminants and fines can be removed from the abrasives in a single-stage fluidized bed. Based on these results, a program to reclaim spent abrasives in IGT's 3-foot-diameter pilot-scale fluidized-bed incinerator was undertaken for the U.s. Navy. The overall objective of this test program was to evaluate the use of the SGFB incinerator for the thermal reclamation of used blasting abrasives. Five kinds of blast grit materials were received for the study: l. Spent coal slag with copper-based paint (coal/Cu) 2 . Spent coal slag with tributyl tin-based paint (coal/TBT) 3 . Spent copper slag with copper-based paint (Cu/Cu) 4. Fresh coal slag abrasive 5. Fresh copper slag abrasive. The two fresh abrasives and the spent coal/Cu and Cu/Cu abrasives were analyzed for total and soluble metals, major oxide components, sieve and subsieve particle-size distribution, and organics measured as carbon and hydrogen. The spent coal/TBT abrasive was analyzed for organics, particle-size distribution, total tin, and organotin specification. Approximately 30 tons of spent abrasives were processed in the pilot incinerator system at abrasive feed rates of about 800 to 1500 lb/h using supplementa l natural gas. No attempt was made to agglomerate the material because it was expected to be reused for blasting. A summary of the operating conditions and results of the pilot-scale test burns with the three abrasives is given in Table 2. Complete analyses for organics, total and soluble metals, major oxides, and size distribution for the coal/Cu and Cu/Cu feed and output streams were performed. Also, analyses for organics, organotin, total tin, and size distribution were conducted for the coal/TBT test. The results of these analyses, shown in Table 3, indicated that the reclaimed materials were suitable for reuse in blast i ng operations. The performance testing clearly demonstrated that the reclaimed abrasive's performance was comparable with fresh -11- INSTITUTE o F GAS TEe H N 0 LOG Y |
