mum and away from the charge bucket will provide energy benefits, as well as reductions in potential fugitive dust.
Cores/Binders Te Casting Emissions Reduction Program (CERP), a
collaboration among the U.S. Department of Defense, envi- ronmental agencies and the private sector, evaluates the haz- ardous air pollutant emission potential of various coremaking processes and binder systems. CERP identified phenolic urethane nobake and coldbox cores as having the highest emissions. Te binder industry responded with options to replace some or all of the aromatic solvents. In ferrous applications, biodiesel binders can reduce ben-
zene, toluene, xylene and naphthalene emissions at pouring, cooling and shakeout by 20-30%. In nonferrous applica- tions, tetraethyl orthosilicate replaces aromatic solvents in parts 1 and 2 of urethane coldbox resins. Tis silicate-based solvent reduces condensate formation and smoke and odor at pouring, cooling and shakeout. Tis is especially impor- tant with the lower pouring temperature used in aluminum semi-permanent molding, as excessive smoke and condensate formation in the die are not only environmental concerns, but they also affect productivity. Even with substitutions, the continued use of phenolic
resins is threatened by lower emission standards. Tis has given rise to a new generation of inorganic
systems such as heat-cured sodium silicates or ester-cured nobake sodium silicate. Te latest generation systems all use some form of aluminosilicate or other inorganic additive to reinforce the water-soluble silicate. Tese systems have little to no volatile organic compounds, are generally non- flammable, generate no odor during mixing, coremaking and shakeout, and generate little to no smoke during casting. Further, many efforts have been made to remove core washing from the coremaking process. In many cases, it can be eliminated with improved coreroom process controls, while for other castings it is a necessity. A novel way to cut core drying costs is to use a color changing indicator in the core wash to determine when it is dry. Drying time and therefore gas consumption can be reduced by 50%.
Air Compressors Te generation and
delivery of compressed air often is inefficient, with one-third of all compressed air horsepower lost in the process. Industry studies have shown the average metalcasting facility may produce 50% more com- pressed air than is required
Melting is the most energy inten- sive part of the casting process and the best opportunity for savings.
可以节省熔化成本。将废料的沙粒和泥土控制到最低限 度，远离装料斗，可以提供能源效益，同时减少潜在的 尘埃。
芯和粘结剂
铸造减排计划(CERP),，一个由美国国防部，环境机 构和私营部门构成的联盟，评估各种制芯工艺和粘结剂 系统可能有危害的空气污染物质排放。铸造减排计划认 定酚醛聚氨酯自硬砂和冷芯盒的排放最高。粘结剂工业 界作出的反应是替换一些或者全部芳香烃溶剂。 在黑色金属铸造中，生物柴油粘结剂可以减少浇注、 冷却和落砂中的苯、甲苯、二甲苯、萘的20%-30%排 放。在有色金属铸造中，在聚氨基甲酸酯树脂冷芯盒的 部位1和2中原硅酸四乙酯可以替代芳香烃粘结剂。这 种硅酸盐基体的溶剂可以降低冷凝物的形成和浇注、冷 却、落砂过程中产生的烟尘和气味。这个在铝合金半金 属型铸造的浇注中浇注温度较低时特别重要，因为在模 具中过多的烟尘和冷凝物形成不仅对环境不利，还影响 生产质量。
虽然有了酚醛树脂的替代物，但是该类产品继续使 用还是受到低排放标准的制约。这已经引起新一代的无 机系，例如热固化硅酸钠或酯固化自硬硅酸钠。最新系 都使用某种形式的铝硅酸盐或其他无机添加剂，以加强 水溶性硅酸盐。这些系统几乎没有任何挥发性有机化合 物，一般不易燃，在混砂、制芯、落砂时无异味产生， 在铸造过程几乎无烟尘产生。
此外还作了很多努力消除在制芯工艺中的型芯清洗。 在很多情况下，改良型芯车间工艺控制可以消除这一环 节，而对于其他铸造它是 必不可少的。有一种新方 法来削减烘干型芯成本， 在型芯涂料中使用干燥的 变色指标剂以确定何时干 燥。这样烘干时间和煤气 消耗可以减少50%。 空气压缩机
压缩空气的产生和传
熔化是最密集的部分能源的鑄 造工藝和儲蓄的最佳機會。
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FOUNDRY-PLANET.COM | MODERN CASTING | CHINA FOUNDRY ASSOCIATION Summer 2011
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