水泥窑协同处置过程中重金属挥发流向规律模拟
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摘要
采用自主研发的静态实验设备和小型水泥回转窑模拟装置,分别模拟静态和动态条件下生料中不同类型重金属在不同温度、反应时间下的挥发特性及流向规律。重金属Pb、Zn、Cd的挥发率均随着温度升高而逐渐升高,同温度下窑煅烧气氛下生料中Pb、Zn、Cd及As的挥发率均低于空气气氛下的挥发率;As挥发率随温度升高先逐渐升高后逐渐减少,重金属氯化物挥发率较高。添加重金属的生料粉在800℃以下的温度煅烧后,物料中主要的晶相为CaCO_3、SiO_2及金属氧化物,CaMg(CO_3)_2的衍射峰主要存在600℃以下。由800℃开始,CaCO_3发生分解,并出现CaO衍射峰;从1 000～1 400℃下,生料粉在重金属作用下逐渐生成较为复杂的化合物。在动态模拟条件下,熟料中As、Cd、Pb及Zn的平均固化率分别为85.48%、83.19%、84.49%、85.20%。绝大部分重金属均存在于熟料中,而挥发到大气中的重金属仅为0.002%～0.2%。
Volatile characteristics and flow rules of different heavy metals in raw meals under different temperatures and response time in static and dynamic status were simulated respectively, by the independently-developed static experimental equipment and small simulator of rotary cement kiln. The volatilization rates of Pb, Zn and Cd all increased with the increase of temperature, and the volatilization rates of Pb, Zn, and Cd and As at the same temperature in kiln calcination atmosphere were all below the corresponding rates in air atmosphere; the volatilization rate of As increased with the increase of temperature and then decreased gradually, and the heavy metal chlorides had a high volatilization rate. The main crystalline phases in raw meals doped with heavy metals after calcination below 800 ℃ were CaCO_3, SiO_2 and metallic oxides, and the diffraction peak of CaMg(CO_3)_2 mainly appeared in the raw meals after calcination below 600 ℃. At 800 ℃, decomposition of CaCO_3 began and was accompanied by diffraction peak of CaO; during 1 000～1 400 ℃, more complex compounds were gradually generated in the raw meals under the action of heavy metals. Under the dynamic simulation condition, the average solidification rates of As, Cd, Pb and Zn in the clinker were 85.48%, 83.19%, 84.49% and 85.20%, respectively. Most of the heavy metals existed in the clinker, while only 0.002%～0.2% were volatilized into the air.
Volatile characteristics and flow rules of different heavy metals in raw meals under different temperatures and response time in static and dynamic status were simulated respectively, by the independently-developed static experimental equipment and small simulator of rotary cement kiln. The volatilization rates of Pb, Zn and Cd all increased with the increase of temperature, and the volatilization rates of Pb, Zn, and Cd and As at the same temperature in kiln calcination atmosphere were all below the corresponding rates in air atmosphere; the volatilization rate of As increased with the increase of temperature and then decreased gradually, and the heavy metal chlorides had a high volatilization rate. The main crystalline phases in raw meals doped with heavy metals after calcination below 800 ℃ were CaCO_3, SiO_2 and metallic oxides, and the diffraction peak of CaMg(CO_3)_2 mainly appeared in the raw meals after calcination below 600 ℃. At 800 ℃, decomposition of CaCO_3 began and was accompanied by diffraction peak of CaO; during 1 000～1 400 ℃, more complex compounds were gradually generated in the raw meals under the action of heavy metals. Under the dynamic simulation condition, the average solidification rates of As, Cd, Pb and Zn in the clinker were 85.48%, 83.19%, 84.49% and 85.20%, respectively. Most of the heavy metals existed in the clinker, while only 0.002%～0.2% were volatilized into the air.
引文
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[18] 何哲祥, 肖祈春, 周喜艳, 等. 铅锌尾矿制备水泥熟料及重金属固化特性 [J]. 中南大学学报(自然科学版), 2015(10): 3961-3968.
[19] 吴学勇, 高永琼, 金宜英. 附烧含重金属废物所得的水泥中重金属的浸出行为研究 [J]. 云南化工, 2008, 35(4): 12-16.
[20] 李波, 蔡玉良, 辛美静, 等. 水泥窑处置废弃物中重金属的迁移行为研究进展 [J]. 中国水泥, 2010(1): 55-59.
[2] Conesa J A, G Lvez A, Mateos F, et al. Organic and inorganic pollutants from cement kiln stack feeding alternative fuels [J]. Journal of Hazardous Materials, 2008, 158(2/3): 585.
[3] Riganti V, Fiumara A, Odobez G B. The use of industrial sludges as raw materials in the cement industry [J]. Waste Management & Research, 1986, 4(1): 293-302.
[4] 杨昱, 黄启飞, 杨玉飞, 等. 废物水泥窑共处置产品中Pb释放的pH影响 [J]. 环境工程, 2009,27(增刊1): 416-420.
[5] Kunal, Siddique R, Rajor A. Use of cement kiln dust in cement concrete and its leachate characteristics [J]. Resources Conservation & Recycling, 2012, 61(7): 59-68.
[6] Sinyoung S, Songsiriritthigul P, Asavapisit S, et al. Chromium behavior during cement-production processes: a clinkerization, hydration, and leaching study [J]. Journal of Hazardous Materials, 2011, 191(1/3): 296-305.
[7] 朱桂珍. 利用水泥回转窑焚烧处理危险废物的评价研究 [J]. 环境科学学报, 2000, 20(6): 14-16.
[8] 朱桂珍. 利用水泥回转窑焚烧处置危险废物的评价研究 [J]. 环境科学学报, 2000, 20(6): 810-812.
[9] 王雷, 李润东, 金宜英, 等. 焚烧飞灰水泥窑共处置过程Pb的迁移模型 [J]. 深圳大学学报(理工版), 2012, 29(6): 509-514.
[10] 王雷, 金宜英, 李润东, 等. 危险废物水泥窑共处置过程Pb的热力学平衡 [J]. 燃烧科学与技术, 2011, 17(3): 224-330.
[11] 丛璟, 闫大海, 李丽, 等. 水泥窑共处置过程中水泥生料对Pb与Cd的吸附/冷凝特性 [J]. 环境工程学报, 2014, 28(10): 575-581.
[12] 崔素萍, 兰明章, 张江, 等. 废弃物中重金属元素在水泥熟料形成过程中的作用及其固化机理 [J]. 硅酸盐学报, 2004, 32(10): 1264-1270.
[13] 兰明章. 重金属在水泥熟料煅烧和水泥水化过程中的行为研究 [D]. 北京:中国建筑材料科学研究总院, 2008.
[14] 李树霞. 城市污水污泥制生态水泥技术研究 [D]. 贵阳:贵州大学, 2009.
[15] 崔敬轩, 闫大海, 李丽, 等. 水泥窑协同处置过程中Pb、Cd的挥发特性 [J]. 环境工程学报, 2013, 7(12): 5001-5006.
[16] 崔敬轩, 闫大海, 李丽, 等. 水泥窑协同处置危险废物过程中铅-镉的挥发动力学研究 [J]. 环境科学学报, 2014, 34(10): 2599-2607.
[17] 肖祈春. 铅锌尾矿制备水泥熟料及其重金属固化特性研究 [D]. 长沙:中南大学, 2014.
[18] 何哲祥, 肖祈春, 周喜艳, 等. 铅锌尾矿制备水泥熟料及重金属固化特性 [J]. 中南大学学报(自然科学版), 2015(10): 3961-3968.
[19] 吴学勇, 高永琼, 金宜英. 附烧含重金属废物所得的水泥中重金属的浸出行为研究 [J]. 云南化工, 2008, 35(4): 12-16.
[20] 李波, 蔡玉良, 辛美静, 等. 水泥窑处置废弃物中重金属的迁移行为研究进展 [J]. 中国水泥, 2010(1): 55-59.