水泥窑铅镉等重金属的污染及防治

POLLUTION AND PREVENTION OF HEAVY METALS SUCH AS LEAD AND CADMIUM IN CEMENT KILNS

利用原子吸收分光光度法、振荡溶出等方法,研究了水泥窑铅镉等重金属污染的防治。氟会促进Pb,Cd,Zn和Cu的逸放。无论何种水泥窑,Hg逸放率高达89%～96%。Pb,Cd,Zn和Cu在不同类型水泥窑中其逸放率有明显差别,立窑的逸放率较高,Pb和Cd为84%～90%,Zn和Cu为36%～47%;湿法回转窑次之;新型干法窑的逸放率最低。使用高效的除尘设备,不仅可减少粉尘的污染,还可减少Pb等重金属的逸放。把Pb等重金属含量较高的窑灰用作水泥混合材既可使Pb等重金属被固封于水泥混凝土中不会产生二次污染,又能减少因窑灰循环入窑而导致Pb等重金属的再次逸放。

Pollution and prevention of heavy metals such as Pb and Cd during cement calcinations were investigated by means of atomic absorption spectroscopy （AAS）, and leaching test. F can promote the emission of Pb, Cd, Zn and Cu. The emission rate of Hg during cement calcinations is very high, in the range from 89% to 96%, whether in the shaft kiln, wet process rotary kiln or suspension preheater kiln. However, the emission rates ofPb, Cd, Zn and Cu are different in different kinds of kilns. The emission rates in shaft kilns are higher than in wet process rotary kilns and suspension preheater kilns. Those of Pb and Cd are in the range from 84% to 90%; those of Zn and Cu are in the range from 36% to 47%. The emission rates of Pb, Cd, Zn and Cu in suspension preheater kilns are the lowest in these three different kinds of kilns. Using a more efficient dust collector can reduce not only fine dust pollution, but also the emission of Pb, Cd, Zn, Cu and Hg pollution. Utilizing kiln dust with high heavy metal content as an additive for cement concrete can prevent the pollution ofPb, Cd, Zn, Cu and Hg in kiln dust.