铅锌硫化矿浮选废水及尾矿库外排水中VOSCs的组成特征及其来源解析

利用臭氧氧化技术对铅锌硫化矿浮选过程各单元作业废水及尾矿库外排水进行处理,根据硫酸根离子浓度增量计算废水中低价态硫(价态小于+6)浓度.采用吹扫捕集-气相色谱质谱联用仪(PTC-GC/MS)检测浮选药剂(丁基二硫代碳酸钠(n-BX)、二乙基二硫代氨基甲酸钠(DDTC)、腐殖酸钠(SH)、松醇油)水溶液的自然降解产物、尾矿库进水及外排水中的挥发性有机硫化物(VOSCs).结果表明,尾矿库主要进水水源中低价态硫浓度为112 mg·L-1,其中,二硫化碳(CS2)在检测组分中所占相对比例为35.60%,是主要的VOSCs物质.各单元作业中浮选作业工段加入大量浮选药剂,浮选药剂水溶液自然降解产物中均检出CS2,而用药量最大的n-BX(C5H9Na OS2)自然降解产物中CS2相对比例最高(80.33%),因此,n-BX是浮选废水中VOSCs主要药剂来源.尾矿库外排水中低价态硫浓度为22 mg·L-1,其中,VOSCs物质主要有3,6-二甲基-1,2,4,5-四硫环己烷(C2H4S4)、N-巯基-甲酰胺(CH2SNO)和2-甲基-3-噻唑啉(C4H7NS),尾矿库外排水中C2H4S4所占相对比例为22.59%,是主要VOSCs物质.尾矿库水体中微生物通过消耗CS2生成C2H4S4进行新陈代谢.本研究结果可为铅锌硫化矿浮选工艺改进和安全排放提供参考.

Composition and source apportionment of volatile organic sulfur compounds in both flotation wastewater and Tailing Reservoir effluent of Pb-Zn sulfide mine

Both wastewater from various unit operations of flotation plant and effluent from Pb-Zn sulfide mine tailing reservoir were treated by ozone oxidation. The sulfate ion increment after the ozone treatment was measured and used to calculate the concentration of low-valent sulfur (<+6) in the wastewater and effluent. Using purge-trap gas chromatography and mass spectrometry (PTC-GC/MS), volatile organic sulfur compounds (VOSCs) in the effluent and influent of reservoir were detected. And the natural degradation products of common flotation reagents in aqueous solution,including butyl xanthate(n-BX),ethyl thiocarbamate(DDTC),sodium humate(SH) and pine oil, will also measured through PTC-GC/MS. The results showed that the concentration of low-valent sulfur (<+6) in the influent of tailing reservoir was 112 mg·L^-1. Carbon disulphide (CS₂) was detected as the main VOSCs of influent and the relative ratio of CS₂ was 35.60%. The flotation reagents were added largely in each floatation unit operation. CS₂ could be detected in the aqueous solutions of three flotation reagents and is the primary natural degradation products. Because the relative ratio of CS₂ in the n-BX solution was the highest (80.33%) and the n-BX dosage was the largest in the unit operations, the n-BX is the main source of VOSCs in the wastewaters of floatation unit operations. The concentration of low-valent sulfur (<+6) in the effluent of tailing reservoir was 22 mg·L^-1. The main contributions to VOSCs included 3,6-dimethyl-1,2,4,5-tetrathiane(C₂H₄S₄), Formamide,N-methylthio(CH₂SNO) and 2-Methyl-2-thiazoline(C₄H₇NS), among which the relative ratio of C₂H₄S₄ was the highest (22.59%). CS₂ can be metabolized to C₂H₄S₄ by microorganism in the mine tailing reservoir. The results of this study provide a reference for the flotation process improvement and safe discharge.