Feasibility and environmental safety investigation of making fired bricks by using heavy metals-contained soil
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摘要:
为探明利用含重金属土壤作为页岩替代原料制备烧结砖的可行性和环境安全性,选取某砖窑以70%的比例掺加该土壤替代页岩开展工业化试验,研究重金属在烟气中的排放情况及在成品砖中的浸出率和分配规律。结果显示:土壤中SiO2、Al2O3和Fe2O3浓度与页岩原料相似,可以用作页岩原料的替代;烧制的成品砖力学性能符合产品质量标准。在以含重金属土壤为原料的砖块烧结过程中,烟气中常规污染物和重金属污染物排放均满足相关标准,环境风险可控;烧结砖中可浸出重金属浓度显著低于GB 30760—2014《水泥窑协同处置固体废物技术规范》浸出限值,砖块在使用过程中的重金属浸出风险较低;As、Cd、Cr、Mn、Ni、Pb和Cu在烧结过程中基本赋存在成品砖里,经烟气挥发和湿法脱硫压滤后留存于脱硫滤饼中的重金属含量极低。研究表明,利用含重金属土壤制备烧结砖从产品力学性能及环境安全性上均能满足现有标准,具有一定的资源化利用效益。
Abstract:Soil heavy metal pollution in China is still relatively serious, and inappropriate disposal of heavy metal contaminated soil can lead to a serious damage to both the ecological environment and human health. However, soil normally contains a significant amount of SiO2, Al2O3 and Fe2O3, which makes it applicable to prepare sintered bricks. In order to ascertain the feasibility and environmental safety of making sintered bricks by using heavy metal contained soil, an industrialization experiment was carried out in a brick kiln, with a blending ratio of 70% soil to replace shale, to investigate the heavy metal emission in flue gas, and the leaching and distribution properties in fired brick. The results revealed that soil had a similar content of SiO2, Al2O3 and Fe2O3 compared to shale, and therefore, it could be used as a substitute for shale raw materials. The mechanical properties of the fired bricks met the product quality standards. During the sintering process with heavy metal soil as raw material, the emission of conventional flue gas pollutants and heavy metal pollutants met the relevant standards, and the environmental risk was controllable. The concentration of leachable heavy metals in sintered bricks was significantly lower than the leaching limit of Technical Specification for Cooperative Disposal of Solid Waste in Cement Kilns (GB 30760-2014 ), and therefore, the leaching risk was low during using bricks. As, Cd, Cr, Mn, Ni, Pb and Cu basically stayed in fired bricks under sintering, and the contents of heavy metals remained in the desulfurization filter cake after flue gas volatilization and wet desulfurization filter pressing were extremely low. The research showed that using heavy metal-contained soil to make sintered brick could meet the existing standards from both mechanical and environmental safety aspects and had certain resource benefits.
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Key words:
- heavy metal /
- contaminated soil /
- fired brick /
- environmental safety /
- leaching and distribution
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表 1 试验用页岩和土壤的化学组成
Table 1. Chemical composition of shale and soil for test
% 试验原料 SiO2 Al2O3 Fe2O3 CaO Na2O K2O MgO 页岩 68.4 18.9 4.6 2.5 0.1 2.6 1.8 土壤 62.6 19.4 6.7 4.0 0.2 2.4 1.5 表 2 试验用页岩和土壤中重金属浓度
Table 2. Heavy metal concentrations of shale and soil for test
mg/kg 试验原料 As Cd Cr Mn Ni Pb Cu 页岩 35.6 5.0 122.3 599.0 41.1 82.8 48.2 土壤 5.2 1.5 400.0 617.2 69.0 55.7 26.4 表 3 2种工况下烟气中常规污染物浓度
Table 3. Concentrations of general pollutants in flue gas under two conditions
mg/m3 污染物 空白工况 掺烧工况 GB 29620—2013
排放限值颗粒物 3.5 3.6 30 SO2 2.6 10.5 150 NOx 18.3 9.1 200 氟化物 0.67 0.31 3 表 4 2种工况下烟气中重金属浓度
Table 4. Concentrations of heavy metals in flue gas under two conditions
mg/m3 重金属 空白工况 掺烧工况 标准排放限值 GB 16297—1996 GB 18484—2020 As 0.037 0.028 0.500 Cd 0.115 0.093 0.850 0.050 Cr 0.409 0.453 0.500 Mn 0.987 1.075 Ni 0.306 0.289 4.300 Pb 0.080 0.094 0.700 0.500 Cu 0.117 0.122 表 5 成品砖中可浸出重金属浓度及控制限值
Table 5. Concentrations and control limits of leachable heavy metals in fired bricks
μg/L 项目 As Cd Cr Mn Ni Pb Cu 空白工况 28.6 0.1 6.5 213.7 7.9 6.0 12.3 掺烧工况 19.8 0.02 5.6 180.8 6.7 3.9 12.6 GB 30760—2014
浸出限值100 30 200 1 000 200 300 1 000 表 6 掺烧工况下成品砖力学性能
Table 6. Mechanical properties of fired bricks under blending condition
项目 掺烧
工况GB/T 5101—2017
标准值尺寸允许
偏差/mm长度平均偏差 −1.5 $ \pm 2.0 $ 长度极差 2.5 $ \leqslant 6.0 $ 宽度平均偏差 −1.5 $ \pm 1.5 $ 宽度极差 1.0 $ \leqslant 5.0 $ 高度平均偏差 −0.8 $ \pm 1.5 $ 高度极差 2.0 $ \leqslant 4.0 $ 外观质量/mm 两条面高度差 1.5 $ \leqslant 2 $ 弯曲 1.3 $ \leqslant 2 $ 杂质凸出高度 1.9 $ \leqslant 2 $ 缺棱掉角的3个破环尺寸 0 $ > 5 $ 大面上宽度方向及其
延伸至条面的长度26.3 $ \leqslant 30 $ 长度方向及其延伸至
顶面的长度或条顶面上
水平裂纹的长度28.9 $ \leqslant 50 $ 抗压强度/MPa 抗压强度平均值 20.67 $ \geqslant 20.0 $ 强度标准值 16.0 $ \geqslant 14.0 $ 放射性核素
限量/(Bq/kg)内照射指数 0.3 $ \leqslant 1.0 $ 外照射指数 0.6 $ \leqslant 1.0 $ 表 7 掺烧工况下重金属在烧结砖隧道窑中的分配率
Table 7. Distribution of heavy metals during co-processing in sintered brick tunnel kiln
% 项目 As Cd Cr Mn Ni Pb Cu 烟气 0.391 0.130 0.065 0.013 0.028 0.048 0.068 脱硫滤饼 0.003 0.001 0.004 0.001 0.003 0.002 0.009 成品砖 99.606 99.869 99.931 99.986 99.969 99.950 99.923 表 8 2种工况下重金属在砖窑中的浸出率
Table 8. Leaching rate of heavy metals in brick tunnel kiln under two conditions
% 工况 As Cd Cr Mn Ni Pb Cu 空白工况 59.0 1.5 2.0 8.1 4.5 2.5 5.8 掺烧工况 40.0 0.3 1.6 4.9 3.5 1.4 5.4 -
[1] 环境保护部, 国土资源部. 全国土壤污染状况调查公报[EB/OL]. (2014-04-17)[2021-10-11]. https://www.mee.gov.cn/gkml/sthjbgw/qt/201404/t20140417_270670_wh.htm. [2] 李继宁, 魏源, 赵龙, 等.锑矿区土壤重金属生物可给性及人体健康风险评估[J]. 环境工程技术学报,2014,4(5):412-420.LI J N, WEI Y, ZHAO L, et al. Bioaccessibility and human health risk assessment of heavy metals in soils of antimony mine area[J]. Journal of Environmental Engineering Technology,2014,4(5):412-420. [3] POLETTINI A, POMI R, TRINCI L, et al. Engineering and environmental properties of thermally treated mixtures containing MSWI fly ash and low-cost additives[J]. Chemosphere,2004,56(10):901-910. doi: 10.1016/j.chemosphere.2004.05.004 [4] 周伟伦, 廖正家, 陈涛, 等.利用铁尾矿制备烧结砖的可行性及烧结固化机理[J]. 环境工程学报,2021,15(5):1670-1678.ZHOU J L, LIAO Z J, CHEN T, et al. Feasibility of using iron tailings to prepare sintering brick and sintering solidification mechanism[J]. Chinese Journal of Environmental Engineering,2021,15(5):1670-1678. [5] WEI Z A, ZHAO J K, WANG W S, et al. Utilizing gold mine tailings to produce sintered bricks[J]. Construction and Building Materials,2021,282:122655. doi: 10.1016/j.conbuildmat.2021.122655 [6] 王晓明.尾矿烧结制砖研究和应用[J]. 中国资源综合利用,2021,39(9):72-75. doi: 10.3969/j.issn.1008-9500.2021.09.022WANG X M. Research and application of making bricks by sintering tailings[J]. China Resources Comprehensive Utilization,2021,39(9):72-75. doi: 10.3969/j.issn.1008-9500.2021.09.022 [7] GOEL G, KATIYAR N K, KIRTHIKA S K, et al. Potential pathway for recycling of the paper mill sludge compost for brick making[J]. Construction and Building Materials,2021,278:122384. doi: 10.1016/j.conbuildmat.2021.122384 [8] 崔敬轩, 何捷, 聂卿, 等.河湖淤泥制备烧结砖的研究进展[J]. 中国建材科技,2020,29(5):37-41.CUI J X, HE J, NIE Q, et al. Research progress on preparation of sintered bricks from river and lake sludge[J]. China Building Materials Science and Technology,2020,29(5):37-41. [9] LEIVA C, ARENAS C, PECENO B, et al. A mechanical, leaching, and radiological assessment of fired bricks with a high content of fly ash[J]. Ceramics International,2018,44:13313-13319. doi: 10.1016/j.ceramint.2018.04.162 [10] TAKI K, GAHLOT R, KUMAR M. Utilization of fly ash amended sewage sludge as brick for sustainable building material with special emphasis on dimensional effect[J]. Journal of Cleaner Production,2020,275:123942. doi: 10.1016/j.jclepro.2020.123942 [11] 张忠亮, 金容旭, 张雪梅, 等.利用海上油气田水基钻井废物制备烧结砖[J]. 环境工程学报,2021,15(9):3020-3028.ZHANG Z L, JIN R X, ZHANG X M, et al. Preparation of sintered brick from water-based drilling wastes in offshore oil and gas field[J]. Chinese Journal of Environmental Engineering,2021,15(9):3020-3028. [12] 王之超, 何洁, 张曼丽, 等.油基钻井岩屑固化体中多环芳烃释放特征[J]. 环境工程技术学报,2020,10(4):647-652.WANG Z C, HE J, ZHANG M L, et al. Release characteristics of PAHs in oil-based drilling cuttings solidified body[J]. Journal of Environmental Engineering Technology,2020,10(4):647-652. [13] LI C, WEN Q, HONG M, et al. Heavy metals leaching in bricks made from lead and zinc mine tailings with varied chemical components[J]. Construction and Building Materials,2017,134:443-451. doi: 10.1016/j.conbuildmat.2016.12.076 [14] GHOSH I, GUHA S, BALASUBRAMANIAM R, et al. Leaching of metals from fresh and sintered red mud[J]. Journal of Hazardous Materials,2011,185(2/3):662-668. [15] CHEN S W, CHENG P C, TU Y T, et al. Variance in heavy metal leachability of Pb-, Ni-, and Cr-contaminated soils through red brick sintering procedure[J]. Environ Monit Assess,2019,191(4):253. doi: 10.1007/s10661-019-7372-9 [16] 田梦莹, 杨玉飞, 黄启飞, 等.烧结砖中重金属释放特性研究[J]. 安全与环境学报,2015,15(6):191-195.TIAN M Y, YANG Y F, HUANG Q F, et al. On the heavy-metal releasing features in sintered bricks[J]. Journal of Safety and Environment,2015,15(6):191-195. [17] 刘敬勇, 孙水裕, 陈涛.固体添加剂对污泥焚烧过程中重金属迁移行为的影响[J]. 环境科学,2013,34(3):1166-1173.LIU J Y, SUN S Y, CHEN T. Effects of adsorbents on partitioning and fixation of heavy metals in the incineration process of sewage sludge[J]. Environmental Science,2013,34(3):1166-1173. [18] 杨柳阳. 重金属在砖窑协同处置过程中的挥发特征及使用过程中释放限值探究[D]. 南京: 南京工业大学, 2021. [19] 徐厚林.烧结砖化学成分及物理性能简述[J]. 砖瓦世界,2015(4):33-34. [20] ARENA U, GREGORIO F. Element partitioning in combustion-and gasification-based waste-to-energy units[J]. Waste Management,2013,33:1142-1150. doi: 10.1016/j.wasman.2013.01.035 [21] 崔敬轩, 闫大海, 李丽, 等.水泥窑共处置过程中砷挥发特性及动力学研究[J]. 中国环境科学,2014,34(6):1498-1504.CUI J X, YAN D H, LI L, et al. Volatilization characteristics and dynamics research on arsenic during co-processing in cement kilns[J]. China Environmental Science,2014,34(6):1498-1504. [22] CONG J, YAN D H, LI L, et al. Volatilization of heavy metals (As, Pb, Cd) during co-processing in cement kilns[J]. Environmental Engineering Science,2015,32(5):425-435. doi: 10.1089/ees.2014.0175 [23] 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.CUI J X, YAN D H, LI L, et al. Volatilizing characteristic of lead and cadmium during co-processing in cement kiln[J]. Chinese Journal of Environmental Engineering,2013,7(12):5001-5006. [24] 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]. 环境科学研究,2015,28(4):575-581.CONG J, YAN D H, LI L, et al. Research on condensation and absorption characteristics of cement raw meal for Pb and Cd during co-processing in cement kiln[J]. Research of Environmental science,2015,28(4):575-581. [25] XU G R, ZOU L J, LI G B. Stabilization of heavy metals in sludge ceramsite[J]. Water Research,2010,44:2930-2938. doi: 10.1016/j.watres.2010.02.014 [26] WANG G W, NING X N, LU X W, et al. Effect of sintering temperature on mineral composition and heavy metals mobility in tailings bricks[J]. Waste Management,2019,93:112-121. doi: 10.1016/j.wasman.2019.04.001 [27] TANG Y, LEE P, SHIH K. Copper sludge from printed circuit board production/recycling for ceramic materials: a quantitative analysis of copper transformation and immobilization[J]. Environmental Science & Technology,2013,47(15):8609-8615. [28] TANG Y, SHIH K, WANG Y, et al. Zinc stabilization efficiency of aluminate spinel structure and its leaching behavior[J]. Environmental Science & Technology,2011,45(24):10544-10550. [29] 杨子良, 岳波, 闫大海, 等.含砷废物资源化产品中砷的浸出特性与环境风险分析[J]. 环境科学研究,2010,23(3):293-297. doi: 10.13198/j.res.2010.03.47.yangzl.007YANG Z L, YUE B, YAN D H, et al. Leaching characteristic and environmental risk analysis of arsenic in resource recovery products using arsenic-containing waste[J]. Research of Environmental Sciences,2010,23(3):293-297. ⊗ doi: 10.13198/j.res.2010.03.47.yangzl.007