Table 5. Percent Change From Baseline When Combining Three Innovations
cycle energy potentially dimin- ishes 0.6% when using 20% coke substitution and 1.5% when using 50% brick substitution (see Table 3). Criteria air emissions fell and emissions of greenhouse gases and VOCs decreased significantly. Another potential method of
replacing coke uses waste heat from the cupola to start pyrolysis of granular bituminous coal that can be made into briquettes using the same binder materials mentioned previously. Te byproducts of this process could be sold and/or used as fuel, though direct and indirect labor is needed because the process takes place on site. Emission reductions are based on the reduced energy required to complete this process. VOCs are condensed as a byproduct or burned directly in the cupola. Tis process has been successfully demonstrated in a full-scale trial and also can produce material suitable to replace metallurgical coke. Te process generates potential
Total System (including upstream)
Energy Fossil
Non-fossil Emissions
Greenhouse gas Criteria pollutants Particulates VOC
Foundry Facility
Materials New sand Collagen
Clay, seacoal, cereal, soda ash Coke
Coke, iron, & scrap Home scrap Ferro-alloys
Other materials & gases Costs
Energy Labor
Materials
Other costs Total
Projected Payback (in years)
energy savings of 3% (Table 3), not including the energy avail- able in the sold byproducts, and greenhouse gases are reduced 2.8%. Criteria pollutant and VOC emissions also improve dramatically due to the closed nature of the process. Overall costs are reduced 20.6%, with the increase in labor costs offset by reduced material and energy costs. Income from the sale of the byproduct materials (shown in “other costs”) is substantial, making the net payback approximately two years.
Tune-Up: Advanced Oxidation With Hydroacoustics A U.S.-based company has devised an advanced
oxidation system that applies ozone, hydrogen peroxide and sonication to a water slurry known as “blackwater” to reprocess baghouse waste dust. The baghouse dust slurry is treated with advanced oxida- tion and replaces the conventional water source for the green sand molds. Research indicates the process, currently in use at 50 iron casting facilities, uses 27-60% less clay and coal, 20-37% less silica sand and produces 19-70% less VOCs during pouring, cooling and shakeout. An upgrade of this process includes hydroacous-
tics, cavitation, recirculation and virtual cyclone (AO-HAC), which has been installed in 10 U.S. facilities. This process acoustically dislodges the hydrophobic carbonaceous coating that forms when volatiles are pyrolyzed from the coal and binders near molten iron. The VOCs then migrate into the cooler green sand mold and recondense. Advanced oxida-
-14.7 -8.3 -2.3 -4.9
-6.6 0.2
-85
17.2 -50 -50
-0.7 -8.6
-10.3 -0.7
-7.5 -8
-58.8 -60
-2 -2.1
另一个有可能代替焦炭的方 法是利用冲天炉的废热，使粒状 烟煤热解，粒状烟煤可用前面提 到的粘结剂制成团块。这个过程 的副产品可以出售和/或用作燃 料，由于这一过程是在现场发生 的，因此需要直接和间接的劳务 作业。减排是建立在完成这一 过程所要求的能源减少的基础上 的。挥发性有机化合物作为副产 品在冲天炉中凝聚或直接燃烧。 这个过程已经在一个全面的试验 中成功演示，也可以生产替代冶 金焦炭的适用材料。
该工艺过程产生的潜在节能达 3%（表3），不包括已售出的副 产品中的可用能量，温室气体减 少2.8%。由于工艺过程的封闭 性，污染物和挥发性有机化合物 的排放指标显著改善。总成本降 低20.6%，原料和能源成本的减
少抵消了劳动力成本的增加。副产品材料的销售收入 （见“其他费用”）是很可观的，使净回报期限大约 只需两年。
优化调整：先进的水声学氧化技术
一家美国公司提出了一种新型的氧化系统，将臭 氧、过氧化氢和高频声波用于被称为“黑水”的泥浆 中，使袋式除尘器收集的粉尘再生。袋式除尘器得到 的泥浆经先进的氧化技术处理，代替用于粘土湿型砂 的传统水源。研究表明，目前50家铸铁厂采用此项 工艺，所用的粘土和煤粉减少27-60%，使用的硅砂 减少20-37%，在浇注、冷却和落砂过程中产生的挥 发性有机化合物减少19-70%。
这项工艺的改进涉及水声学、空化、再循环和虚 拟气旋(AO-HAC)，并已在10个美国工厂安装。型 砂-铁液的界面处，型砂中的煤粉和粘结剂热解挥发 时形成的疏水碳质涂层，这项工艺由声频使疏水涂层 沉积。之后，挥发性有机化合物转移到较冷的湿型砂 中，进行再凝聚。先进氧化技术将粘土和砂表面的凝 聚挥发物去除，恢复粘土的亲水粘结性能，并防止他 们在造型、浇注、冷却和落砂过程中再次挥发。
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FOUNDRY-PLANET.COM | MODERN CASTING | CHINA FOUNDRY ASSOCIATION June 2014
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