Reaearch on environmental stability and heavy metals release characteristics of gypsum sludge from waste acid treatment
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摘要:
为探究火法炼铜过程产生的污酸石膏渣的环境风险,通过解析污酸石膏渣性质,采用模拟堆存、静态侵蚀、半动态侵蚀的方法研究污酸石膏渣的长期稳定性与重金属释放特性。结果表明,污酸石膏渣中As、Cd浸出浓度超标,分别为1 488.66、22.98 mg/L。其中,As的酸可提取态达87.55%,Cd的有效态超90%,存在严重环境风险。模拟堆存结果表明,污酸石膏渣为严重生态风险等级,应做好防淋失、防扬尘等措施。在静态与半动态侵蚀下,污酸石膏渣表面附着的As、Cd在化学反应、扩散等作用下大量浸出,使浓度均处于较高水平。其中,模拟填埋场环境各元素浸出浓度远高于其他模拟环境,需重点关注。
Abstract:In order to explore the environmental risk of waste acid gypsum sludge produced by the thermal copper refining process, the long-term stability and heavy metal release characteristics of waste acid gypsum sludge were investigated using the methods of simulated stockpiling, static erosion, and semi-dynamic erosion. The findings indicate that the waste acid gypsum sludge has a leaching concentration of As and Cd that is higher than the standard (1488.66 and 22.98 mg/L, respectively), with As reaching an acid-extractable state of 87.55% and Cd effective state exceeding 90%, which poses a serious environmental risk. The results of the simulated stockpiling demonstrate that shower loss and dust should be prevented because waste acid gypsum sludge poses a serious ecological risk level. As and Cd adhered to the surface of waste acid gypsum sludge are leached out in significant amounts by chemical reaction and diffusion during static and semi-dynamic erosion, resulting in concentrations that are all quite high. Among them, the leaching concentration of each element in the landfill simulation environment is significantly larger than that in other simulation environments, which requires special attention.
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表 1 重金属毒性响应因子取值
Table 1. Toxicity coefficient of heavy metals
As Cd Cr Cu Pb Zn 10 30 2 5 5 1 表 2 $ {E}_{{r}}^{i} $, PERI与金属污染水平的关系
Table 2. Relationship among $ {{E}}_{{r}}^{{i}} $, PERI and metal pollution level
$ {E}_{r}^{i} $ 单一潜在生态
风险等级PERI 综合潜在生态
风险等级<40 轻微生态危害 <150 轻微风险 40~80 中等生态危害 150~300 中等风险 80~160 强生态危害 300~600 高风险 160~320 很强生态危害 ≥600 严重风险 ≥320 极强生态危害 表 3 污酸石膏渣的元素组成与含量
Table 3. Elemental composition and contents of waste acid gypsum sludge
% 元素 含量 元素 含量 Ca 26.0 Zn 0.17 S 24.6 Fe 0.086 As 3.36 Mg 0.13 Na 0.94 Al 0.088 Cd 0.22 Hg 0.0008 Pb 0.099 Cr 0.0007 Cu 0.069 Sb 0.03 表 4 污酸石膏渣中金属元素浸出毒性及超标倍数
Table 4. Leaching toxicity concentration and exceeding ratio of metal elements in waste acid gypsum sludge
元素 浸出浓度/(mg/L) 浸出毒性标准/(mg/L) 超标倍数 As 1 488.66 5 296.73 Cd 22.98 1 22.98 Cu 0.10 100 Pb 0.14 5 Zn 49.67 100 表 5 污酸石膏渣模拟堆存前后的潜在生态风险值
Table 5. Potential ecological risk values of waste acid gypsum sludge before and after simulated stockpiling
样品 EAs ECd ECu EPb EZn PERI 原样 数值 5 347.747 910.952 0.147 5.541 7.819 6 272.206 等级 极强 极强 轻微 轻微 轻微 严重 末期 数值 4 513.323 999.470 0.161 4.773 7.063 5 524.790 等级 极强 极强 轻微 轻微 轻微 严重 表 6 常见的动力学方程
Table 6. Common dynamic equations
表 7 污酸石膏渣静态浸出动力学方程拟合结果
Table 7. Results of kinetic equation fitting for static leaching of waste acid gypsum sludge
元素 模拟环境 符合模型 相关系数 模型参数 As GW Elovich方程 0.903 83 a=2.846 18 b=3.518 22 AR1 Elovich方程 0.656 00 a=4.084 23 b=3.269 54 AR2 Elovich方程 0.943 34 a=2.364 08 b=3.154 70 LF 混合控制 0.985 84 k=0.017 32 Ca GW Elovich方程 0.986 33 a=14.854 28 AR1 Elovich方程 0.698 09 b=2.547 33 AR2 Elovich方程 0.970 30 a=12.508 44 b=3.747 59 LF Elovich方程 0.981 43 a=14.726 67 b=2.045 24 Cd LF Avrami模型 0.998 36 k=0.001 01 n=1.884 37 Cu LF 内扩散控制 0.967 13 k=0.000 11 Zn LF 未收缩反应核
模型-外扩散控制0.986 28 k=0.009 12 表 8 污酸石膏渣半动态浸出动力学方程拟合结果
Table 8. Results of dynamic equation fitting for semi-dynamic leaching of treatment of waste acid gypsum sludge
元素 模拟环境 符合模型 相关系数 模型参数 元素 模拟环境 符合模型 相关系数 模型参数 As GW 双常数模型 0.967 63 a=9.349 22 Cd GW 内扩散控制 0.988 61 k=0.000 04 b=0.072 45 AR1 内扩散控制 0.982 32 k=0.000 04 AR1 Avrami模型 0.989 67 k=0.309 55 AR2 Avrami模型 0.984 67 k=0.015 25 n=0.076 97 n=0.730 69 AR2 Elovich方程 0.977 98 a=10 353.910 7 LF 内扩散控制 0.984 35 k=0.006 79 b=1 333.918 71 Cu LF Avrami模型 0.998 94 k=0.002 78 LF Elovich方程 0.854 65 a=19 665.248 0 n=1.864 79 b=1 369.819 21 Zn GW 界面化学反应控制 0.987 86 k=0.000 17 Ca GW Avrami模型 0.992 75 k=0.016 57 AR1 界面化学反应控制 0.985 05 k=0.000 17 n=0.757 21 AR2 Avrami模型 0.989 66 k=0.005 44 AR1 Avrami模型 0.991 83 k=0.015 90 n=0.792 99 n=0.767 36 LF Avrami模型 0.896 53 k=0.570 36 AR2 内扩散控制 0.990 89 k=0.000 22 n=0.407 48 LF Avrami模型 0.990 61 k=0.016 50 Pb LF Avrami模型 0.995 02 k=0.046 96 n=0.754 45 n=0.748 24 -
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