and multiple casting or production lines, which requires a continuous and on-time supply of the melt. At Jintang, three centrifugal casting lines produce DN80-DN800 pipe, with an annual production of 100,000 tons. A 6-m DN80-DN800 pipe weighs from 90 to 1,400 kg, so the casting line heavily depends on continuous and on-time melt supply. Te pairing of a blast furnace and medium frequency
induction furnace can satisfy the supply of the melt. Unlike the traditional duplex process with a cupola furnace, using a blast furnace in conjunction with a medium frequency induc- tion furnace omits the re-melting process, resulting in lower sulfur content, less element loss, lower energy consumption and lower discharge of pollutants. At Jintang, the melt is shipped from the blast furnace to
the cast pipe workshop via a 20-ton iron tank. Te workshop operates two 10-ton, 2,500-kw induction furnaces, along with a spectrum analysis device, microscope and mechanical properties testers. Jintang utilizes the wire feeding nodular- izing technique in production. Tapping temperature is 1,400C, with a 50C decrease
during shipping and treating. Te cold mold reject rate is less than 5%. Te addition of scrap and reject is around 10%. Energy consumption is 220-280 kWh per ton. Te cast pipes are tempered in a continuous tempering furnace equipped with dual burning systems that burn off the gas produced by the blast furnace. Te cast pipes consistently fall into the specification of ISO2531-2003.
Shortcut Technology for Small and Medium Iron Castings
Jintang’s two small and medium iron casting lines
have an annual output of 20,000 tons. The main prod- ucts include automotive castings, valves and castings for
供应符合要求的铁水是高效优质地生产合格产品的关 键。所以, 在生产中对铁水的成分和温度要求严格控制, 并应保证连续供应。
离心铸造球墨铸铁管, 首先要保证原铁水的化学成分, 尤其要注意对Mn、P、S、Ti、Cr 等元素的严格控制。 表1 列出了津唐公司铸管用高炉铁水的化学成分。 离心铸造生产的特点是, 产品规格多, 生产效率高, 且 多采用多机或多生产线作业。因此, 要求铁液的供应连 续、及时。津唐公司球墨铸铁管车间配备DN80-DN800 口径离心铸管机共3 台， 生产能力为10万t/年。一根作 业长度6m的DN80-DN800 球墨铸铁管, 重量小者不足 90kg, 大者近1,400kg。这样大的铁液需要量, 若不能连 续及时供应, 生产便无法正常进行。高炉+中频感应电炉 不仅满足了连续供应铁水的需要，而且与冲天炉+中频 感应电炉工艺相比，由于省去了重熔过程，具有铁水含 硫量低、元素烧损少、节能减排的独特优势。 铁水使用20t铁水罐从高炉运至铸管车间，车间配备
2台10t一拖二感应电炉，功率2500kW,并配备直读光谱 分析仪、金相显微镜、机械性能实验设备，采用喂丝球 化处理工艺。
高炉出铁温度1400℃，运输、兑铁过程降温约50℃ 。冷模法离心球墨铸铁管综合合格率约95%，废钢、 废管等冷料加入量10%，每吨铸造铁水耗电量220 ～280kWh。铸管退火采用连续式退火炉，使用高炉 煤气为燃料，双预热燃烧方式，铸管性能稳定达到 ISO2531-2003规定的标准。
二．短流程铸造工艺在普通中小型铸件生产中的 应用
津唐公司建有 2条铸件生产线， 年产铸件2万t， 主要产品有：汽 车铸件、阀门铸 件、通用机械铸 件等，铸件最大 重量50kg,最小重 量3kg，铸铁牌号
Fig. 1. Shown is the recycling pattern at Jintang Foundry.
津唐铸造工业园循 环经济模式图
Fall 2011
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