INDUSTRY NEWS/行業新聞
Recent Study Shows Chinese Metalcasters Can Save on Energy, Waste Materials
中国铸造装备与节能减排 According to a recent study, materials and energy account
for 55-70% of the total in Chinese metal casting production, illustrating a significant potential for savings in that area of the industry.
Te study was launched in response to the fact that high
energy consumption, heavy pollution and intensive labor have been are linked to the metalcasting industry. According to the data, the energy consumption of China’s metalcasting industry is 25-30% of the total of the machinery industry, with a energy utility rate of 17%, double that of developed countries. Te study also indicated the gross weight of cast- ings is 10-20% heavier than that of developed countries, and yield is 55%, compared to 70% in foreign countries. Te statistics showed that energy consumption for melting is 79% of the total for metalcasting facilities using electric furnaces. Tis energy consumption during melting was shown to offer potential for reduction. In developing countries, the power usage of induction furnaces reaches 75%, with the efficiency of induction coils at 85%. Te best level in China achieves 73%, with a coil efficiency of 80%, almost equivalent to the leading international level. Te difference was found to lie in the preparation and purifica- tion of charge materials. Overseas facilities achieve greater charge uniformity, with high purity and size requirements. At Chinese plants, charge quality is lower, and fewer cutting tools and purification equipment are available. Chinese casting facilities also have the opportunity to
reuse residual heat during the annealing process, according to the study. In some facilities, the residual heat of recycling cooling water for electric furnaces is used for bathing or room heating. However, there is no standard for these processes. Te wastes discharged from Chinese metalcasting facili-
ties include used sand, slag and dust. Generally speaking, the facilities discharge a ton of wasted sand per ton of metal castings produced—70% of the facilities’ total discharge. Equipment for resin sand and green sand recycling are being designed and developed in China; however, the application of green sand recycling isn’t yet popular. To reduce dust pollution, the material is collected and sent to mixers to improve casting surface quality and reduce the use of coal dust and bentonite. Many metalcasters have constructed a dust transportation room in their sand disposal workshops. Other dust is sent to a hopper located on the top of mixers for reuse. Te recent study showed that other measures, such as improving the reliability of equipment, de- creasing reject rates and adopting hollow cores, can be taken to reduce the discharge. ■
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谈到铸造，很多人就会想到高能耗、重污染、强体 力劳动，因此，在论述铸造装备时，不能不谈到节能减 排问题。
我国铸造行业的能耗占机械工业总耗能的25% ～30%，能源平均利用率为17%，能耗约为铸造发达 国家的2倍。据统计，铸件生产过程中材料和能源的投 入约占产值的55%～70%。我国铸件毛重比国外平均 重10%～20%，铸钢件工艺出品率平均为55%，国外 可达70%。由此可见我国铸造能耗方面还有较大的降低 空间。
据统计，采用电炉熔化的铸造车间，熔化所占电耗 的比例在79%左右，因此，铸造节能主要是如何降低熔 化所需要的能量和如何利用熔融铁液到形成常温铸件的 过程中所释放的能量。实际上国外先进的感应电炉总效 率可达75%，感应线圈电效率可达85%。国内较好电 炉生产企业生产的电炉总效率可达73%，线圈电效率达 80%，两项指标与国外先进水平基本相当。关键是炉料 准备和炉料净化不同。国外要求炉料一致性要好，在洁 净度、块度上都有要求，而我国多数企业的炉料废钢都 采购于社会，品质难以保证，更没有专门的炉料切割和 净化设备。
关于余热利用方面，目前主要是利用余热退火，部 分企业已利用电炉循环水余热进行采暖或洗澡，但这些 都没有标准的产品。
铸造的主要废弃物是废砂、废渣、粉尘，通常情况 下，一吨合格铸件要排放一吨废砂，废砂的排放量占铸 造总排放量的70%左右，因此，铸造减排首先就是减少 废砂排放。为此，我国逐渐开发了树脂砂再生设备、粘 土砂再生设备，但目前，粘土砂再生设备应用的还不普 遍。为了减少粉尘，对于相当一部分铸件，除尘器收集 的废灰，加入混砂机后不仅能提高铸件表面质量，而且 还能降低煤粉、粘土的加入量，因此，目前不少新铸造 厂都在砂处理车间设置一个废灰发送间，将除尘器的部 分废灰直接发送到混砂机上方的灰斗内，进行再利用。 此外，还有提高设备可靠性、降低废品率、砂芯抽空等 措施，减少废弃物排放。 ■
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Summer 2011
FOUNDRY-PLANET.COM | MODERN CASTING | CHINA FOUNDRY ASSOCIATION | 29
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