粗锌真空蒸馏规律的研究

目前国内外皆采用常压精馏的方法精炼火法生产出的粗锌。本文探讨了采用真空蒸馏法精炼粗锌的可能性。由理论计算得到６５０℃时，在Ｚｎ—Ｐｈ及Ｚｎ—Ｃｄ系富锌端，分离系数βＰｂ＝２．２７４ｘ１０～－３，βＣｄ＝２６．７５２，说明锌铅分离效果很好，锌镉仍有可能分离。小型试验研究了温度、残压、熔体深度、蒸馏时间等因素对锌、铅、镉蒸馏的影响，得出了真空蒸馏粗锌的有关基本规律和作业条件。     

高镉锌真空蒸馏分离锌镉的研究

对高镉锌真空蒸馏分离锌、镉进行了理论分析和实验研究,考察了蒸馏温度、保温时间对锌、镉分离效果的影响。理论研究表明:在真空条件下高镉锌中的锌与镉具有分离的可能性。实验结果表明:提高蒸馏温度和延长保温时间,都有利于提高金属镉的直收率,但均会降低挥发物中镉的纯度;当系统压力保持在30 Pa时,蒸馏温度为400℃,保温时间为60 min条件下,挥发物中的镉纯度为96.5%,镉直收率为60.1%,残余物中锌纯度为87.42%;并在实验研究结果中验证了多次蒸馏可提高挥发物中镉的纯度,三次蒸馏挥发物中的镉纯度可达99.99%。此工艺为真空蒸馏分离高镉锌中锌与镉提供新的方法,对采用真空蒸馏法处理高镉锌具有一定的指导意义和应用价值。     

高砷粗铅真空蒸馏脱除砷的研究

采用鼓风炉熔炼高砷粗铅为原料,对其真空蒸馏脱除砷进行理论分析和实验研究,考察蒸馏温度、恒温时间对砷脱除率、金属铅直收率的影响。理论分析结果表明:砷与铅的饱和蒸气压差异较大,且两者不形成金属间化合物,在较低的蒸馏温度条件下,高砷粗铅真空蒸馏可以有效地脱除砷。实验结果表明:在系统压力为5~15 Pa,蒸馏温度为973 K,蒸馏时间为30 min的条件下,砷的脱除率为80%,铅的直收率为97%,粗铅中铜的存在对砷的脱除有较大的影响。此工艺为粗铅真空蒸馏脱除砷提供新的方法,对粗铅采用真空蒸馏精炼除砷具有一定的指导意义和应用价值。     

真空蒸馏分离脆硫铅锑精矿中闪锌矿的实验研究

提出了一种利用真空蒸馏从脆硫铅锑精矿中分离闪锌矿的方法,从理论上分析了闪锌矿与脆硫铅锑精矿分离的可行性并开展了实验研究。理论计算结果表明,Sb_2S_3,PbS,ZnS和FeS在实验温度范围内挥发性依次减弱且不会分解。对实验样品采取化学分析及X射线衍射和能量色散谱物相分析,探究蒸馏温度和保温时间对闪锌矿分离富集效果的影响,分析结果表明,通过真空蒸馏脆硫铅锑精矿的方法可以实现闪锌矿与其他硫化物的分离和富集,在温度为1073~1573 K,随着蒸馏温度和保温时间的增加,锌的富集比出现先增加后稳定的趋势,蒸馏温度的对闪锌矿分离的影响大于保温时间。当保温时间为1.0 h,蒸馏温度为1473 K,系统压力为50 Pa时,锌以闪锌矿形式存在于冷凝盘中,锌含量高达66.32%,接近于纯硫化锌中锌的含量66.67%。该方法为脆硫铅锑矿的冶炼提供的新方法,同时为含有闪锌矿的其他矿物提取闪锌矿提供了新思路。     

铅锑合金的真空蒸馏实验研究

回收利用铅、锑冶炼和消费过程中产生的铅锑合金意义重大。本文计算了923~1373 K温度范围内纯铅和纯锑的饱和蒸气压、锑的分离系数和气液相平衡成分图,从热力学上分析了铅锑合金真空蒸馏分离的可行性。计算结果表明:铅、锑能够通过真空蒸馏实现较好分离。进一步实验研究了蒸馏温度、时间以及不同成分Pb-Sb合金真空分离效果。实验结果表明:在973 K,蒸馏时间30 min,炉内压强5~10 Pa条件下对合金进行真空分离,气相中富集57.44%的锑,液相中得到88.82%的粗铅。     

粗金真空蒸馏脱除银锌铜的研究

研究了真空蒸馏法脱除银锌铜的理论和实验的可行性。利用真空电阻炉,以质量分数为93.98%的粗金为原料,进行真空蒸馏实验,研究了蒸馏温度,蒸馏时间对金直收率及银锌铜的脱除率的影响。实验结果表明:在真空炉压强为10~30 Pa,蒸馏温度为1773 K,蒸馏时间为60 min的条件下,银的脱除率达到99%以上,锌的脱除率接近100%,残留物金中的铜含量低于2%,一次真空蒸馏残留物中金的直收率大于80%,此工艺为真空蒸馏分离粗金中银锌铜提供的新方法,并使银得到有效的富集,对粗金采用真空蒸馏法脱除银锌铜具有指导意义。     

硬锌提锌和富集锗铟技术的研究与应用

硬锌是火法炼锌过程中的副产物,含有多种金属元素,采用真空蒸馏的方法综合处理硬锌、使锗、铟、银富集在蒸馏残渣中,锌蒸发得到提纯,在温度为１１７３～１２２３Ｋ真空度为１３３．３Ｐａ时,锗富集在渣中的倍数为１０倍,直收率大珩９６％;铟的富集倍数为４倍,直收率大于９０％,产出锌的品位大于９９％,直收率为８０％。     

真空蒸馏铟锡合金回收金属铟的研究

采用真空电阻炉对铟锡合金进行了实验研究。首先通过实验确定了较好的蒸馏时间和蒸馏温度范围。最后根据化验结果确定了对生产具有指导意义的实验条件,即对金属铟质量分数为90%的铟锡合金进行真空蒸馏时,采取的对生产具有指导意义的工艺条件为蒸馏温度1250℃,蒸馏时间60 min;蒸馏温度1300℃,蒸馏时间40 min;所得的金属铟的含铟量大于99%。     

粗铟真空蒸馏多级冷凝法提纯的实验研究

本实验采用真空蒸馏多级冷凝提纯粗铟的实验研究,其特点是通过高温真空蒸馏使得粗铟挥发,根据不同金属元素冷凝温度的不同,设置适合的冷凝温度梯度,从而达到除杂提纯的效果,实验表明,由于冷凝温度的不同杂质元素分别冷凝在1-10级的冷凝盘的两端,而金属铟主要集中在中间冷凝盘中。最佳条件:温度1400℃,保温1 h,压强为10~15 Pa,此时铟主要分布在中间3-6冷凝盘中,其中杂质元素Cu、Cd、Fe、Al、Sn主要分布在1-2级和杂质元素Pb、Tl主要分布在8-10级冷凝盘,其中3、4冷凝盘中铟纯度为99.9%,直收率为53.87%,5、6冷凝盘的铟纯度为99.99%,直收率为36.7%,,因此99.9%以上的直收率达到90%以上,杂质可以达到4~6 N(99.99%~99.9999%)铟的国家标准要求。     

真空蒸馏法提纯粗镍的研究

本研究利用纯度为99.96%粗Ni为原料,进行真空蒸馏实验,在1773~1973K温度下和保温2.5 h及真空度小于10 Pa的实验条件下进行真空蒸馏。以实验结果为依据计算了产物中各种杂质的Yi,αi,βi,γoi的实验值,从热力学角度分析了这些杂质与主体元素Ni的分离程度。确定采用真空蒸馏的方法将粗Ni提纯除杂工艺的可行性,并得到纯度为99.99%的金属Ni。     

Purification of cadmium up to 5N+ by vacuum distillation

Cadmium was refined by vacuum distillation, a technique suitable for low boiling and melting point materials, to remove the heavy and low vapour pressure impurities at ppm level. The detailed analysis of the purified Cd as well as raw Cd was done by ICP-OES techniques for 27 impurity elements. Purification was carried out in an efficient high-yield vacuum distillation system designed and fabricated for purifying 3N+ purity indigenous cadmium to 5N+ (99.999%). Analysis confirmed the reduction of total impurity content from 134 ppm (3N7) for raw Cd to 3 ppm (5N7) upon vacuum distilled Cd. The present study shows that the analysis of impurities such as Fe, Mg and Ca are contributed from environmental effect, whereas impurities such as Pb, Bi, Ag, Ni, Cu, Zn and Tl require adaptation of elemental analysing technique to counter dilution effect. The Hg trace analysis can however be carried out by hydride generation techniques.     

真空蒸馏铅阳极泥制备粗锑的研究

采用高锑铅阳极泥为原料,对其真空蒸馏制备粗锑的原理和工艺进行探讨,理论和实验均证实了该方法的可行性。试验结果表明:系统压力5~10 Pa,蒸馏时间60 min,一次蒸馏温度在923~1143 K范围内均可得到含Sb量大于84%的粗锑。Sb,Pb的脱除率随蒸馏时间的延长而增大。X射线衍射仪研究表明冷凝物中Sb为单质态Sb,其纯度受Pb,Bi,As含量影响较大。将一次蒸馏冷凝物分别在温度为873,773 K真空蒸馏分离Pb,Bi,As后可获得纯度为95.2%的粗锑。此工艺流程短,操作简单,无污染,符合冶金工业清洁生产的发展需求。     

Preparation of 6N high-purity indium by method of physical-chemical purification and electrorefining

The increasing demands for indium in recent years require high purity indium as raw materials. Physical-chemical purification and electrorefining have been performed to obtain 6N high purity indium. Indium is smelted by using NaOH, NaCl and NaNO₃ for 20 min at 400°C, the removing rate of Sn, Zn, Al reaches 40, 60 and 37% respectively. The removing rate of Cd is 90–95% and that of Tl reaches 40–60% when indium is smelted for 10 min by 20% glycerin solution of KI and I₂ at 180°C. When indium metal is vacuum refined in two stages: 800–900°C for 2 h and 950–1050°C for 2 h, the major impurity elements, Pb, Zn, and Bi, are effectively removed. When indium is electrolytic refined in In₂(SO₄)₃-H₂SO₄ system, in which indium content is 60–80 g/L, pH 2.0–3.0, current density 50–80 A/m², the content of impurities can be dropped and the product of indium reaches 99.9999%.     

铟锡合金真空蒸馏分离的研究

研究了真空蒸馏法分离铟锡合金,回收金属铟与锡的新工艺。从理论上分析了铟与锡分离的可能性和规律性,并进行工业化试验。工业化试验的结果表明,控制蒸馏温度1050℃,真空度3 Pa时,铟锡合金中的铟与锡能在较大程度上分离开,得到含铟量大于95%的粗铟,粗铟中的含锡量降至1%以下。铟的直收率达到92%,物料的总回收率达到99%。该方法是铟锡分离中流程短、无污染、低能耗的新工艺、新技术。     

Purification of cadmium by selective volatilization in vacuum in presence of oxide phase on its melt

Purification of cadmium in the presence of a thin (~0·001?mm) oxide layer on the surface of the molten metal was carried out using a simple system designed and fabricated locally. The analytical results revealed that the distillation through oxide layer gave better separation for Co, Ni, Cu, Zn, Ag, Sn, Hg and Tl, when compared to the distillation without oxide layer. This was attributed due to the impurity metal oxide phases formation on the surface of the molten metal. The influence of oxygen flow time on the distillation rate of cadmium was established. There was no excess oxygen (O) retained in the distillate after two consecutive vacuum distillations through oxide route. The experiments were conducted at the level of nearly 1·5?kg a batch to study the impurities behaviour due to upscaling. The detailed chemical analysis of 58 impurity elements in Cd in presence and absence of oxide layer was carried out by glow discharge mass spectrometry (GDMS).     

Process methodology for the small scale production of m6N5 purity zinc using a resistance heated vacuum distillation system

Ultra high purity Zn (m6N5) was obtained through triple vacuum distillation using an m4N5 Zn as input material. High-volatile impurities were removed from the zinc matrix by vacuum evaporation, while traces having lower volatility than the matrix remained in the residual material after finishing of the entire purification process. The time required for the removal of the main high-volatile impurity (Cd) was monitored using a connected gas source mass spectrometer. During distillation the Zn vapor of the distillate was condensed on the cap of a glassy carbon crucible which was water cooled by a movable copper block. The temperatures were optimized for the removal of the volatiles and for the distillation process using vapor pressure data. High resolution glow discharge mass spectrometry was applied for the analysis and purity evaluation of the distilled and input zinc. The analysis confirmed the reduction of the metallic impurities from 43 mg kg⁻¹ to 0.5 mg kg⁻¹ (m6N5) after three consecutive vacuum distillations. An increase in the grain size and a decrease in the micro-hardness were observed for the purified Zn material.     

The effect of metals on the growth of plants: The use of experimental design and response surfaces in a study of the influence of Tl,Cd, Zn,Fe and Pb on barley seedlings

A quadratic model for the influence of factors on an observed response is described, including the effect of the values of coefficients on the shape of the response curve. The univariate response parameters, and cross-product (competitive) response terms can be deduced using a three-factorial central composite experimental design, providing response and factors are suitably coded. Two experiments in which barley seedlings are grown in varying concentrations of Tl, Cd and Pb and of Tl, Fe and Zn are described; observed root and shoot lengths are analysed by response surface methodology. It is shown that the order of toxicity is Tl > Cd > Pb > Zn ≈ Fe (root) and Tl > Cd > Zn ≈ Pb > Fe (shoot). The methods are also validated by comparing predicted curves for Tl in both experiments and by comparing Tl and Cd from the factorial experiment to Tl and Cd when used alone. Various methods for scaling the observed response are compared.     

Comparison of indium purification between vacuum refining and electrowinning

Vacuum refining and electrowinning experiments of indium metal with 99.97% purity have been performed to compare the behavior of impurity metals during refining. When indium metal was vacuum refined at 1000°C and 1.32 × 10^–8 atm for one hour, the major impurity elements, Pb and Bi, were effectively removed while Al, Cu and Sn were not removed.During electrowinning, solution pH, temperature and NaCl concentration had negligible effects on the current efficiency of electrowinning from the chloride solutions in the experimental ranges. However, a high concentration of indium and NaCl was important in achieving high energy efficiency. By employing electrowinning, the impurity metals in the indium such as Bi, Pb, Al, Mg and Cd were removed while copper was not removed.     

Preparation and adsorbing performance of calcium titanate with template method

In this paper, using furfural residue as a template, porous calcium titanate (FPCT) was prepared by a sol-gel method and characterized by XRD, SEM, and nitrogen adsorption method. The conditions of preparation were investigated. The adsorption capabilities of FPCT for heavy metal ions were studied, and the adsorption mechanism was investigated. The results show that the calcium titanate was porous, and material is composed of crystals in nanoparticle size with a small amount of calcium sulfate impurities, while the sulfuric acid in furfural residue is fixed as the calcium sulfate in the material. The adsorbed quantity is affected by the pH value of medium and time. When the pH value of medium is 5, and oscillating adsorption lasts for 30?min, the adsorbed quantities of Cd, Pb, Zn, Cu, and Ni are 118.04, 197.96, 64.98, 56.85, and 47.91?mg/g, respectively. The adsorption conforms to the Langmuir adsorption isothermal model and pseudo-second-order kinetic equation, and is a spontaneous endothermic process driven by entropy. After adsorption, adsorbents can be regenerated with 1?mol/L nitrate solution. It is used for eliminating Cd, Pb, Zn, Cu, and Ni in wastewater and the results are satisfactory.