This page contains a Flash digital edition of a book.
consuming 15-20% of the raw coal’s energy and releasing an equivalent amount of its carbon as greenhouse gases and VOCs. Technological advances may reduce or eliminate such emissions by either partially or completely replacing coke. A second proposed technology capitalizes on the exhausted cupola heat to yield a lignite-based activated carbon. Tis lignite can adsorb VOC emissions, and the loaded lignite can be used in green sand molds in place of bitumi- nous seacoal and as feedstock for a coke replacement.


Te first of these options is to use waste anthracite fines formed into bricks to partially replace coke and ferrosilicon (see Figure 2). Tese bricks use binder materials made from collagen, silicon/silicate and other biomaterials to match the strength and energy value of coke. Te anthracite fines and biomaterials used in these bricks have limited value as low-grade fuel or are otherwise waste. Also, the bricks include silicon, which is charged into the cupola to provide silicon to the cast iron and control the cupola’s redox level. Tese bricks include 85% anthracite fines, 10% biomaterials and 5% silicon/silicate. Te binders become thermally conditioned within the cupola to provide strength from ambient temperature to iron melting temperature. Tese bricks have 35-40% higher BTU content per volume than coke and burn as quickly. Tese formed anthracite bricks


favorable olive-green slag color that indicated suitably reduced condi- tions for metallic iron formation. Te


were used in a full-scale cupola facility in Pennsylvania. Tis trial employed four tons of bricks formed with biomaterials, with 25% substitution of the bricks for coke for a half day. Te bricks remained intact during rough handling when charged into the cupola and were still intact as they descended to the tuyere windows, where temperatures reached 3,000F (1,550C). During this brick substitu- tion, the total carbon charged into the furnace (i.e., carbon in the coke plus bricks) decreased 6%, while main- taining a constant melt temperature, more favorable CO/CO2


ratio and a


carbon content of the iron product remained constant, while the iron maintained acceptable levels of silicon, sulfur and other trace metals. Te demonstrations maintained the iron product quality. Te more effective energy release could diminish natural gas require- ments in metalcasting facilities that


inject supplemental natural gas into the cupola. Te anthracite bricks must be dried at 248F (120C), which requires considerably less energy than coking coke at 1,652-1,832F (900- 1,000C) for 26-30 hours. Tis study estimates the impacts


of two variations of coke replace- ment: 20% and 50% replacement of


March 2014 MODERN CASTING | 45


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92  |  Page 93  |  Page 94  |  Page 95  |  Page 96  |  Page 97  |  Page 98  |  Page 99  |  Page 100