铅膏预脱硫副产物硫酸钠溶液净化与结晶实验研究

发布时间：2018-07-02 23:48

  本文选题：铅膏预脱硫 + Na_2SO_4　； 参考：《湘潭大学》2017年硕士论文

【摘要】：我国再生铅企业目前采用的主要是传统的铅膏火法再生工艺,这种处理工艺会造成严重的环境污染和资源浪费。国外采用环保型的湿法脱硫—低温熔炼工艺,我国《再生铅准入条件》明确规定“对分选出的铅膏必须进行脱硫预处理或送硫化铅精矿冶炼厂合并处理,脱硫母液必须进行处理并回收副产品”,国家大力推行绿色低碳的铅膏预脱硫湿法处理工艺,以年处理15万吨废铅酸蓄电池为例,采用碳酸钠作脱硫剂,约产生副产物硫酸钠2万吨,因此铅膏预脱硫副产物硫酸钠资源化回收显得尤为重要。本论文针对铅膏预脱硫Na_2SO_4母液的净化与结晶工艺进行实验研究。首先,对于铅膏预脱硫Na_2SO_4母液中重金属(Pb~(2+)、Cd~(2+)、Cu~(2+))和金属杂质离子Fe~(2+)/Fe~(3+)的净化提出了铁碳微电解-混凝沉淀的处理工艺,分别进行了铁碳微电解实验、混凝沉淀实验和铁碳微电解-混凝沉淀实验。在铁碳微电解-混凝沉淀实验中,重点研究了停留时间、铁碳合金添加量、金属杂质离子初始浓度、pH值、曝气量等5个因素对于Na_2SO_4母液中重金属和金属杂质离子Fe~(2+)/Fe~(3+)净化效果的影响。在最佳运行条件下,通过铁碳微电解-混凝沉淀法净化后,Pb~(2+)、Cd~(2+)、Cu~(2+)、Fe~(2+)/Fe~(3+)的去除率分别为99.2%、99.1%、97.9%、97.3%,Na_2SO_4母液中重金属和金属杂质离子总含量≤5mg/L。其次,对于净化后的Na_2SO_4母液结晶,本课题组提出了一种基于局部冷却快速析晶的结晶新方法。该方法不直接对储罐内溶液降温,而是在外循环的支路上施加冷媒,造成循环部分流体的快速深度降温,从而能够更充分地析出晶体。实验测定了不同质量分数Na_2SO_4溶液降温饱和结晶点温度,探究了不同质量分数Na_2SO_4、最低结晶温度对Na_2SO_4析出率和产品品质的影响。考虑到能耗和经济效益,本实验确定最低结晶温度为5℃。实验研究的局部冷却快速析晶法,能量利用率高,产品析出率高,连续运行,系统简单可靠。最后,在废铅酸蓄电池再生企业组建了铁碳微电解-混凝沉淀+基于局部冷却快速析晶法回收Na_2SO_4中试实验装置,中试实验采用铅膏预脱硫后Na_2SO_4母液,其中Na_2SO_4质量分数为16%-28%,处理量为10 m3/h,中试验证了Na_2SO_4母液净化与结晶总工艺,中试结果表明:铁碳微电解-混凝沉淀+基于局部冷却快速析晶法对铅膏预脱硫副产物Na_2SO_4母液的净化与结晶具有良好的适应性,系统运行稳定,设备操作简单,产品Na_2SO_4品质符合国标《GB/T6009-2014》Ⅰ类一等品标准,中试产生的冷却结晶水满足前段工艺生产需求,可直接回用。
[Abstract]:At present, the traditional pyrolysis process is mainly used in the lead recycling enterprises in China, which will cause serious environmental pollution and waste of resources. Environmental friendly wet desulphurization and low temperature smelting process have been adopted abroad. In our country, it is clearly stipulated that "desulphurization pretreatment or combined treatment of lead sulfide concentrate smelter must be carried out for the selected lead paste." The mother liquor of desulphurization must be treated and the by-product should be recovered. "the national government has vigorously promoted the green low carbon lead paste pre-desulphurization wet treatment process. Taking 150000 tons of waste lead-acid batteries treated annually as an example, sodium carbonate is used as desulfurization agent. About 20,000 tons of sodium sulfate is produced, so it is very important to recycle the by-product of lead paste. In this paper, the purification and crystallization process of Na _ 2SO _ 4 mother liquor for predesulfurization of lead paste was studied. First of all, for the purification of heavy metals (PB2) and metal impurity ions Fe2 / Fe3 in the Na2SO4 mother liquor predesulfurized by lead paste, the iron-carbon micro-electrolysis and coagulation precipitation processes were put forward, and the iron-carbon microelectrolysis experiments were carried out, respectively, for the purification of heavy metals (Pb ~ (2) and metal impurity ions (Fe ~ (2) / Fe ~ (3). Coagulation precipitation test and iron carbon micro electrolysis-coagulation precipitation experiment. In the experiment of iron-carbon micro-electrolysis and coagulation precipitation, the residence time, the amount of iron and carbon alloy, the initial concentration of metal impurity ion and pH value were studied. The effect of aeration rate on the purification efficiency of heavy metal and metal impurity Fe ~ (2) / Fe ~ (3) in Na2SO4 mother liquor. Under the optimum operating conditions, the removal rates of Fe ~ (2 +) -Fe ~ (2) / Fe ~ (3) in Fe ~ (2 +) -Fe ~ (2) / Fe ~ (3) ratio after purification by iron-carbon microelectrolysis and coagulation precipitation were 99.2 / 99.1 / 97.997. 3% respectively. The total contents of heavy metals and metal impurity ions in Na2SO4 mother liquor were 鈮，

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