逐级沉淀法从高酸度高盐度微蚀刻废液中回收石膏及铜金属的研究

发布时间：2018-02-06 03:56

本文关键词： 微蚀刻废液含盐高酸度大逐级沉淀法资源回收　出处：《广东工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：印刷线路板微蚀刻废液含铜量高、含盐高、酸度大,是电镀废水处理的难题。现在采用的方法有电解法、沉淀法,电解法回收金属铜后的微蚀刻废液酸度大、含盐高,还含有少量的铜。据广州某电镀厂的处理现状,对该废水采取的处理方法是投加大量的碱中和后再进入后续生化处理系统继续进行处理,处理成本高达250元/m3。由于在此处理过程中并未考虑硫酸根离子的回收,使得中和后出水中硫酸根离子浓度过高,对微生物产生抑制和毒害作用,从而严重影响生物处理系统的净化效果,使得出水水质不能稳定达标排放。本文对该电解回收铜后的微蚀刻废液进行处理,采用逐级沉淀法,有效回收废液中高浓度的硫酸根降低盐度后,再用较少的碱中和废液、回收剩余的少量的金属铜,该工艺不仅操作方便,耗碱少,降低了处理成本,而且同时回收了硫酸根制备石膏和回收了铜金属。该厂每月排放1000m3的经电解后的微蚀刻废液,所取废水pH为0.5,硫酸根含量高达72g/L,铜离子浓度为787mg/L。采用逐级沉淀法进行实验与研究,得到的主要结果如下：1、氢氧化钙一级沉淀。取某电镀厂的废水100mL,确定的氢氧化钙的投加量为3.55g,产生石膏7.5g,硫酸钙纯度为80.68%,S042-的去除率为57.48%；此时pH升至2.0,Cu2+由于硫酸钙沉淀的机械夹带浓度从787mg/L降至748mg/L2、氯化钙二级沉淀。取经第一步反应后的滤液100mL,确定氯化钙的投加量为3.5g,产生的石膏4.13g,硫酸钙纯度为75.87%,一级、二级沉淀SO42-总的去除率已达到了94.33%;此时pH降至1.3,铜离子浓度基本上没有发生变化。3、铜离子三级沉淀。处理经前两级沉淀后的滤液100mL:(1)单纯加氢氧化钠,投加量为0.5g,铜的去除率为99.37%,出水中铜离子未达到GB 21900-2008中表3的排放标准；(2)单纯加硫化钠,投加量为0.45g,铜的去除率为99.90%,出水中铜离子也未达到GB 21900-2008中表3的排放标准，硫化钠沉淀法虽然对铜的去除率更高,但出水水质pH值低,影响废水的后续生物处理过程,而且会有硫化氢气体产生,造成二次污染；(3)为了使出水中铜离子的浓度经三级沉淀后能达到GB 21900-2008中表3规定的0.3mg/L的排放浓度限值,向二级沉淀后的废水中加入0.4g NaOH调节pH后,再加入0.55g Na2S产生沉淀,铜离子浓度降到0.3mg/L以下,pH为8.5,出水达到了表3的排放标准；没有刺激性的硫化氢气体产生,得到的铜渣含铜为21.23%,具有较大的经济效益。4、高纯度石膏的制备。用5%的硫酸清洗一级沉淀的建材石膏,石膏纯度可达98.1%,作业回收率为84%；用5%的硫酸清洗二级沉淀的建材石膏,石膏纯度可达94.22%,作业回收率为84%。5、采用Ca(OH)2+CaCl2+NaOH+Na2S逐级沉淀法处理经电解回收铜后的微蚀刻废液的过程中,处理每立方米废水的药剂费为114.7元,生成的建材石膏的价值为12元,生成的铜副产品的价值为19.25元,得出该类废水总的处理费用为83元/m3,比现在的处理费250元/m3节省了167元/m3。6、该技术流程设计科学严谨,依据废水中各种物质成分的特性,设计有效的逐级沉淀法处理废水；实现了废水的达标排放和资源的回收,环境效益和经济效益显著。该技术在国内外未见相关报道,有较大的理论和实际意义,对同类企业的废水处理有重要的参考价值。
[Abstract]:The printed circuit board of the micro etching waste liquor containing high copper content, high salt, high acidity, is a difficult problem in electroplating wastewater treatment. Now the method with electrolysis, precipitation, recovery of copper electrolysis after micro etching solution acidity, high salt, also contains a small amount of copper plating. According to a Guangzhou factory processing status, treatment methods of the wastewater is taken with the addition of alkali neutralization before entering the subsequent biochemical treatment system to continue treatment, treatment costs up to 250 yuan /m3. because this process is not considered in the recovery of sulfate ion, and makes out the sulfate ion concentration in the water is too high, and suppress toxic effects on microorganisms, which can seriously affect the purification effect of the biological treatment system, the water quality stable discharge. The electrolytic copper recovery after micro etching wastewater treated by stepwise precipitation method, effective return Received a high concentration of sulfate reducing salinity waste, with less alkali waste, recycling a small amount of metal copper surplus, this process has the advantages of convenient operation, less consumption of alkali, reducing processing cost, and at the same time the recovery of sulfate gypsum preparation and recovery of copper metal. The plant monthly emissions by 1000m3 micro etching wastewater after electrolysis, the wastewater pH is 0.5, the sulfate content of up to 72g/L, the concentration of copper ion to 787mg/L. by step by step experiment and research of precipitation method, the main results obtained are as follows: 1. The level of calcium hydroxide precipitation. 100mL wastewater from an electroplating factory, determine the dosage of calcium hydroxide 3.55g 7.5G, the formation of gypsum, calcium sulfate purity is 80.68%, the removal rate of S042- was 57.48%; the pH rose to 2 Cu2+ due to mechanical entrainment concentration of calcium sulfate precipitation from 787mg/L to 748mg/L2, and two calcium chloride precipitation. Take the first step after the reaction The filtrate of 100mL, determination of calcium chloride dosage was 3.5G, gypsum 4.13g, calcium sulfate purity is 75.87%, a level two level, precipitation SO42- total removal rate has reached 94.33%; at pH to 1.3, no change in.3 concentration of copper ion basically, copper ions of three precipitation treatment. The first two 100mL: of the filtrate after precipitation (1) with pure sodium hydroxide dosage was 0.5g, the copper removal rate is 99.37%, the effluent of copper ion in GB 3 does not meet the emission standards in table 21900-2008; (2) the simple addition of sodium sulfide, the dosage is 0.45g, the removal rate of copper is 99.90%, water copper ion in GB 3 does not meet the emission standards in table 21900-2008, although the precipitation of copper sulfide removal rate is higher, but the effluent pH value is low, affect the subsequent biological treatment process of wastewater, and hydrogen sulfide gas produced, cause two pollution; (3) to use copper ion in water. The emission concentration of three precipitation can reach GB 21900-2008 in Table 3 provides the 0.3mg/L limit value, adding 0.4g NaOH to the two level of wastewater after precipitation in the regulation of pH after adding 0.55g Na2S precipitate, copper ion concentration is below 0.3mg/L, pH is 8.5, the effluent can meet the emission standards in Table 3 no stimulation; hydrogen sulfide gas produced in the copper slag, the copper content is 21.23%, with economic benefits of large.4, high purity gypsum building plaster preparation. The primary sedimentation cleaning with 5% sulfuric acid and gypsum purity of 98.1% and the recovery rate was 84%; two grade building plaster cleaning precipitation by 5% sulfate, gypsum 94.22% purity, recovery rate of 84%.5, using Ca (OH) 2+CaCl2+NaOH+Na2S step by step precipitation treatment by electrolytic copper recovery after micro etching waste liquid in the process of wastewater treatment agent fee is 114.7 yuan per cubic meter, building materials gypsum formation The value of 12 yuan, copper byproduct of the value of 19.25 yuan, the total treatment cost of the wastewater is 83 yuan /m3, than the current processing fee of 250 yuan /m3 saved 167 yuan /m3.6, the design of scientific rigor, according to the characteristics of various substances in wastewater composition, wastewater treatment by sedimentation the design of effective implementation step by step; discharge of wastewater and recycling resources, environmental and economic benefits. The technology at home and abroad has not been reported, there is great theoretical and practical significance, has important reference value for the similar enterprise's wastewater treatment.

【学位授予单位】：广东工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X781.1

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