【作者】 胡根火；

【导师】 刘志宏；

【作者基本信息】 中南大学 ， 有色金属冶金， 2011， 硕士

【摘要】 深度净化不仅可提高电流效率与电锌质量,也是实现机械剥锌的前提条件,是湿法炼锌溶液净化的主要发展趋势。目前,我国湿法炼锌溶液净化技术,与国际先进水平比较,仍有一定差距,存在净化深度偏低、锌粉耗量过大等问题,因此,加强这一领域的研究,具有重要意义。锑盐法是目前应用最广的硫酸锌溶液净化除钻工艺。在锑盐法净化除钴中,国内外许多工厂都采用向溶液中加入一定量的硫酸铜或一段净化时保留少量Cu2+、Cd2+的方法,强化锌粉置换除钴,但是对Cu2+、Cd2+的加入量及其影响规律,仍存在较大争议；此外,在锌粉净化除钴中,锌粉活性随净化时间的延长逐渐降低,以致除钴速率减缓、锌粉消耗增加,通常认为,这是由于锌粉表面生成了碱式硫酸锌,阻碍传质过程所致,强化传质是解决这一问题的思路之一。针对上述两方面的问题,本论文系统研究了添加Cu2+、Cd2+对锑盐净化除钴的影响,并探索研究了超声波对锑盐净化除钴过程的作用。实验研究了未添加Cu2+、Cd2+条件下的锑盐净化除钴过程。考察了锌粉种类、锌粉用量、锑盐用量、温度、搅拌速度、溶液初始pH值等因素对置换除钴速率及净化深度的影响。结果表明,锌粉性质对置换除钴影响很大,采用含有少量Pb和Sb、粒度较细的锌粉,既能加快除钴速率,提高除钴的深度、还可减少锌粉用量；升高温度可显著提高除钴速率,实验确定锌粉置换除钴过程的表观活化能为90kJ/mol,表明锑盐净化除钴过程为化学步骤控制；实验确定的最佳工艺条件：温度85℃,锌粉用量2g/L,锑盐用量3mg/L,搅拌速度300r/min,溶液初始pH值4。在锑盐净化除钴最佳条件下,实验研究了添加Cu2+、Cd2+的影响。结果表明,单独添加一定量的Cu2+,不但能够提高除钴速率,而且可在较少锌粉用量下,实现溶液深度净化；在最佳Cu2+添加量50mg/L下,可使溶液中的[Co2+]在90 min内降至0.1 mg/L；单独添加少量的Cd2+有利于锑盐净化除钻,但其添加量过多(如150mg/L),反而对除钴过程有害；同时添加Cu2+、Cd2+,除钻效果比单独添加Cu2+时更好,与未添加Cu2+、Cd2+时相比,可以在更低的温度下使[C02+]达到更低的水平,实验确定的最优除钻工艺条件为：[Cu2+]015mg/L [Cd2+]015mg/L、锑盐用量3mg/L、锌粉用量2g/L、温度85℃、搅拌速度300 r/min,溶液初始pH值4,在此条件下净化60min,溶液中[C02+]降低至0.078mg/L探索研究了超声波对锑盐净化除钴过程的影响,得出的初步结论为：超声波对提高锌粉置换除钴速率具有一定的作用；超声波功率在160W范围内,置换率随功率的增大而增大,而超出此范围,继续增大功率则不利于除钴；高频率(如100kHz)超声波对净化除钻有利,若超声波净化时间超过60min,低频率(如45kHz)超声波更易促使已沉积的钴返溶。更多还原

【Abstract】 Deep purification is the major trend in purifying zinc sulfate solution, which can not only improve the current efficiency and quality of the electrowined zinc, but also is the prerequisite of realizing mechanization of zinc ripping. There is still a certain gap for purification technology in our country compared with the international advanced level, such as lower purity of zinc sulfate solution, larger zinc dust consumption and so on, therefore, there is of great significance in strengthening research in this area.Antimony salt process is the most widely used for cobalt removal from zinc sulfate solution. In order to strengthen the process, many factories abroad and at home adopt the method of adding a certain amount of copper sulfate to the solution or retaining a small amount of Cu(Ⅱ) ions and Cd(Ⅱ) ions in the stage of removing copper and cadmium, but the addition amounts of Cu(Ⅱ) ions and Cd(Ⅱ) ions, as well as their effects on cementation of cobalt are still in dispute. In addition, the activeness of zinc dust present in the solution reduces gradually along with the time in the purification process, which always leads to the rate of cobalt removal slow and the dosage of zinc dust increase. Generally speaking, this is due to the basic zinc sulfate formed on the surfaces of zinc dust hinder the process of mass transfer in the purification process, therefore enhancing mass transfer is one idea to solve this problem. To deal with these two problems, the effects of adding Cu(II) ions and Cd(II) ions were systematically investigated in the paper, and also a preliminary study was carried out on the effect of ultrasonic wave on the cobalt cementation process by zinc dust.Experiments on cobalt removal using antimony salt as additive in the absence of Cu(Ⅱ) ions and Cd(Ⅱ) ions were carried out firstly. The effects of such factors, as types of zinc dust, dosage of zinc dust, dosage of antimony salt, temperature, stirring speed and initial pH value were examined on the rate of cobalt removal, as well as the purities of the zinc sulfate solution. The results showed that the characteristics of zinc dust used have a large effect on the purification of cobalt. Using zinc dust with finer particle size and containing a little amount of Pb, Sb, can not only increases the purities of zinc sulfate solution, saves the dosage of zinc dust used, but also accelerates the cobalt removal rate; Increasing temperature can increase the cobalt removal rate significantly, and the apparent activation energy for the process was calculated equal to 90 kJ/mol according to experimental results, suggesting that the cobalt removal process is controlled by a surface chemical reaction; The optimal conditions for cobalt removal without Cu(II) and Ca(Ⅱ) ions addition were obtained to be as follows:temperature 85℃, zinc dust dosage 2 g/L, antimony salt dosage 3 mg/L, stirring speed 300 r/min, initial pH 4.The effects of adding Cu(Ⅱ) ions and Cd(Ⅱ) ions on cobalt removal were investigated under the optimal conditions described above. The result showed that adding solely a certain amount of Cu(II) ions not only increases the cobalt removal rate, but also decrease zinc dust dosage added to obtain a deep purification, the optimal addition amount of Cu(Ⅱ) ions was determined to be 50 mg/L, which will result [Co2+] bellow 0.1 mg/L after purifying for 90 minutes; adding solely a certain amount of Cd(II) ions was beneficial to the process, but a Cd(II) ions concentration up to 150 mg/L would be harmful to cobalt removal; It was also validated that adding Cu(Ⅱ) and Cd(Ⅱ) ions at the same time behaves a better effects of cobalt removal than that of adding Cu(II) ions solely, and furthermore, compared with that in the absence of Cu(Ⅱ) ions and Cd(Ⅱ) ions, can obtain a low [Co2+] under a lower temperature. The optimal conditions for cobalt removal were obtained to be as follows:[Cu2+]015 mg/L, [Cd2+]015 mg/L, antimony salt dosage 3 mg/L, zinc dust dosage 2 g/L, temperature 85℃and stirring speed 300 r/min, initial pH 4.A primary investigation on the effect of ultrasonic wave on cobalt removal by zinc dust cementation was carried out, and the main conclusions were as follows:the rate of cobalt removal can be accelerate to a certain extent in the presence of ultrasonic wave; the higher the power of ultrasonic wave up to 160 W in the experiments, the higher the cobalt removal rate; but further increase of the ultrasonic power beyond this range was deleterious to the cobalt removal; the presence of ultrasonic wave with a higher frequency (e.g.100 kHz) was beneficial to the cobalt removal process, while the presence of ultrasonic wave with a lower frequency (e.g.45 kHz) accelerated the redissolution of cobalt deposited after an effecting duration for 60 min.更多还原