Removal of the Harmful Elements and Iron Recovery from the Blast Furnace Gas Ash by Chloridizing Roasting
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摘要: 包钢高炉瓦斯灰由于受白云鄂博铁矿石成分复杂性的影响,其含铁量低、有害元素碱金属氧化物K2O、Na2O和Pb、Zn氧化物含量高。通过利用瓦斯灰中的碳、或在瓦斯灰中配入氯化钙,采用还原-蒸发-磁选、氯化-挥发的方法,使其中的钾、钠、铅和锌氧化物转变为易蒸发的单质或转化为易挥发的氯化物,从而达到与瓦斯灰分离的目的。还原-蒸发-磁选试验结果表明:在温度为1 000℃,反应时间为2 h时,Na、Pb、Zn的去除率可达到94.21%、98.53%、91.98%,而K不能通过碳还原去除;以950℃、反应2.0 h的还原-蒸发产物为原料进行磁选,当磁选电流为0.6 A时,铁的回收率达90.24%。氯化-挥发试验结果表明:当温度为1 000℃时,Pb、Zn的去除率分别为99.62%、85.56%;Na、K的去除受温度影响不大,在试验条件下,均可达到98%以上,K的去除是通过氯化反应进行的,而Na的去除是碳的还原和氯化反应同时进行的结果,但氯化反应更易发生。Abstract: Due to the complexity of Bayan Obo iron ore,the blast furnace gas ash of Baotou steel has low content of iron but is rich in harmful alkali metal oxides like K2O and Na2O as well as oxides of Pb and Zn. Two methods named reduction-evaporation-magnetic separation and chlorination-evaporation were introduced in this paper to transform the mentioned oxides into metals or volatile chlorides respectively by the carbon in the ash or adding calcium chloride into the ash,by which the harmful elements can be separated and the residual iron can be recovered from the ash. The results of reduction-evaporation-magnetic separation experiments show that under condition of 1000 ℃ for 2 h the removal rate of Na,Pb and Zn is respectively 94.21%,98.53% and 91.98%,while K cannot be removed by carbon reduction. With the products of reduction-evaporation at 950 ℃ for 2 h as raw materials for magnetic separation,the recovery rate of Fe reaches 90.24% with 0.6 A current. The results of chlorination-evaporation experiments indicate that the removal rate of Pb and Zn can separately reach 99.62% and 85.56% with 1000 ℃ of temperature. Removal of K and Na is barely affected by temperature with both more than 98% of removal rate. K is removed by chlorination reaction. Nevertheless,Na is separated both by carbon reduction and chlorination in which it's easier for the latter.
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Key words:
- blast furnace /
- gas ash /
- reduction /
- evaporation /
- magnetic separation /
- chlorination /
- removal ratio
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