电沉积法从硫氰酸盐浸金液回收金的试验研究

针对硫氰酸盐浸金液金回收效率低且成本高等问题,利用电沉积法从硫氰酸铵浸金液中回收金。采用单因素法研究了阳极材料、阴极材料、极间距、槽电压、溶液pH值和温度对金沉积率的影响,结果表明:以石墨棒作阳极、自制电极作阴极,在极间距为10 mm、槽电压为4 V、溶液pH=12和温度为35℃的条件下,电解2 h,金沉积率达到98.95%。采用响应面法研究了槽电压、溶液pH值与溶液温度之间的交互作用及其对金沉积率的影响,结果表明:各因素对金沉积率的影响程度依次为槽电压>溶液pH值>溶液温度,并建立了电沉积金响应面回归模型。在槽电压为4.10 V、溶液pH=12.40和温度为39.58℃的最佳条件下,模型预测值为99.06%,试验平均值为99.04%,二者结果非常接近,证明该模型能够对金沉积率进行准确的分析预测。本研究进一步完善了硫氰酸盐提金工艺理论体系。

锌粉置换硫代硫酸盐浸金液中金试验研究

以10μg/L金标准液与硫代硫酸钠、氨水合成浸金液,采用锌粉置换法回收所合成浸金液中的金。结果表明:锌粉用量增加,金置换率提高;选取锌粉用量为0.4 g/L,随反应时间增加,金置换率下降;浸金液中铜离子和单质S、SO_4^(2-)、SO_3^(2-)等多硫化物对置换反应不利;游离硫代硫酸盐对置换影响较小;添加铅盐对置换反应有利。SEM-EDS分析表明,经5%乙酸铅溶液浸泡后的锌粉表面有铅生成,生成的铅与锌形成电偶加速置换反应,同时,锌粉表面变蓬松,增大了锌粉与Au(S_2O_3)_2^(3-)的接触面积,有利于置换反应的进行。

P507从酸性硫脲浸金液中回收金

研究了用P507的煤油溶液作为萃取剂,从酸性硫脲(TU)浸金液中回收金的性能. 用浓度为1.65 mol/L的P507萃取剂在料液[H2SO4]=0.335 mol/L, 相比O/A=1:1,两相接触时间5 min的条件下萃取金,得到金的一级萃取率达99.80%;用50 g/L的Na2SO3溶液反萃,一级反萃率达82.45%,同时达到金、铁的分离.

石油亚砜从硫脲浸金液中萃取金的研究

探讨了用石油亚砜从酸性硫脲浸金液中萃取Ａｕ（Ｉ）的性能及用Ｎａ＿２ＳＯ＿３溶液从负载有机相中反萃Ａｕ（Ｉ）的可能性，并在振动筛板塔中进行了扩大试验。

酸性硫脲浸金液中金的富集研究

研究了D 0 72大孔强酸性阳离子交换树脂从硫脲 [Tu =CS(NH2 ) 2 ]浸金液中吸附Au(Tu) + 2 的性能和机理。结果表明 :在 pH =2 .0时 ,树脂对Au(Tu) + 2 有优良的吸附性能 ,1 gD 0 72大孔强酸性阳离子交换树脂金的交换容量为 78.95mg ,吸附的硫脲金可用乙醇 -硫酸水溶液洗脱 ,洗脱率可达 96 .5 %。D 0 72树脂对Au(Tu) +

用分光光度法测定氰化浸金液中的SCN^-

利用Fe3+与SCN^-的配合反应,建立测定氰化浸金液中SCN^-的分光光度法,优化波长、溶液pH、硝酸铁用量等测定最佳参数。方法对氰化浸金液中高浓度SCN^-的测定有很好的适用性,且操作简单、快速,准确性和精密度较高。SCN^-质量浓度与其吸光度在仪器测量范围内呈良好的线性关系,方法检出限为0.30mg/L,相对标准偏差小于2.50%,加标回收率为94.30%～101.13%。

水合肼还原-重量法测定氯化浸金液中金含量

采用水合肼还原氯化浸金液(氯金酸溶液)中的金,称量析出海绵金的质量,实现了海绵金的准确测定,考查了反应温度、试液金浓度、水合肼使用量等对于测定结果的影响,并与其它测定方法进行了比对。调整氯化浸金液金浓度约为40 g/L,加入水合肼(用量1.5 mL/g-Au)还原后加热溶液微沸20 min,损失在滤液中的金量可忽略。测定结果的相对标准偏差(RSD)小于0.2%。方法操作简便,可满足生产分析的要求。

容量法测定浸金液中的硫脲

本文介绍了容量法测定浸金液中的硫脲，试验了浸取液中各组分对测定的干扰及其消除方法，初步探明了硫脲法浸金过程及从浸出液中回收金的过程中硫脲损耗的情况。

浸金液降酸还原试验研究与应用

对王水分金过程中产生浸金液的酸度进行分析,从理论上明确了预中和的可行性。通过试验研究,获得了在浸金液中加入中和剂(片碱)降低其酸度的工艺参数。同时,进行了工业试验验证,确定了浸金液酸度控制在0.7 mol/L时再进行还原较适宜。该项研究应用于工业生产,取得了较好的经济效益和环境效益。

铜阳极泥氯化浸金液连续萃铜试验

针对铜阳极泥氯化浸金液含铜高造成稀贵金属置换困难且损失量大的问题,采用Lix984萃取分离铜,进行萃取槽连续试验,考察铜萃取率变化,分析存在的问题并探讨解决方案。试验发现采用Lix984从含铜10~20g/L和Cl-~200g/L的氯化浸金液中分离和回收铜,技术上可行。在萃取混合时间3min、萃取相比(O/A)2/1、反萃水相为180~260g/L硫酸条件下,经过4级萃取、2级洗涤和2级反萃,铜直收率可达99%以上。金、银、钯、铅、镍等不被萃取,仅有少量夹带,可洗涤回收。萃取过程发生界面污物累积和乳化,主要与料液含固量高、金属离子水解、相比和搅拌速度不当、萃取剂降解等因素有关,可通过精滤、过渡槽调pH值、实时监控流量和转速、定期补充萃取剂和清除第三相等措施,实现萃取稳定运行。

SK-800型原子荧光测金仪在黄金矿山的应用

通过对西安索坤技术开发有限公司研制的原子荧光测金仪在黄金矿山的应用试验 ,建立了相应的分析方法 ,同时还对选矿工艺中的氰化浸金液、活性炭吸附后的贫液、原矿、尾矿及载金炭中金的含量进行了测定 ,并获得了令人满意的结果 ,完全达到和满足了矿山生产的要求。该方法与化学法和其它类型的仪器法比较 ,具有灵敏度高 (DL :3.9× 10 - 3μg/ml)、重现性好 (RSD <2 .0 % )、分析速度快等特点[1] ,同时也成功地进行了银。

Security Risk Analysis on the Nutrients and Heavy Metals of Biogas Slurry in Agricultural Application

[Objective] This study was to provide scientific basis for the security application of biogas slurry in agriculture through the analysis on the security risk of nu- trients and heavy metals of biogas slurry in agricultural application. [Method] The components of the slurry produced by the anaerobic digestion of straws and manures were systematically analyzed. Different types of biogas slurry with different concentrations were used to conduct the germination test. [Result] The types and proportions of raw materials, and alkali pretreatment affected the compositions and nature of the biogas slurry. Alkali pretreatment could reduce the contents of heavy metals and improved the contents of nitrogen, phosphorous, organic matter and available components. The contents of heavy metals in the biogas slurry were as follows： Cd of 8.76 μg/kg, Cr of 52μg/kg, Pb of 210 μg/kg, Hg of 0.512 μg/kg, As of 140μg/kg, and the contents of Cu and Zn were the highest among the heavy metals, respectively, 279 and 680 μg/kg. All the contents were under the limit standards of the urban wastes for agricultural use. The germination tests of the seeds verified that the slurry with the concentration of lower than 5% could accelerate the germination, while the salt stress could inhibit the growth of seedlings in the slurry. [Conclusion] When the dung are uses as the raw materials for fermentation, appropriate control should be conducted on the feeding proportion or the heavy metals should be pre-removed; when the slurry is used as the liquid fertilizer to apply in the farmland, the dilution or desalting treatment should be conducted at first.

Surface pretreatment of Mg alloys prior to Al electroplating in TMPAC-AlCl_3 ionic liquids

It is difficult to directly electroplate Al on Mg alloys. The effects of pretreatment parameters on the corrosion resistance of films obtained on AZ31 Mg alloy surface were studied by using potentiodynamic polarization curves, to produce a compact interfacial layer as zinc-immersion deposition. After the substrate was pretreated under optimized conditions, aluminum was electrodeposited on AZ31 from TMPAC-AlCl3 room temperature ionic liquids. The depositions were characterized by scanning electron microscope equipped with energy dispersion X-ray. The results show that the traditional pretreatment of Mg alloys was successfully used for the Al-electroplating process from TMPAC-AlCl3 ionic liquids. The entire procedure includes alkaline cleaning, chemical pickling, surface activation （400 mL/L HF acid, 10 min）, zinc-immersion （20 min） and anhydrous treatment. A relatively compact zinc-immersion film was prepared on the substrate surface. A silvery-colored satin aluminum deposition was obtained on AZ31 from TMPAC-AlCl3 using direct current plating.

Corrosion and leaching behaviors of Sn-based alloy in simulated soil solutions

The corrosion and leaching behaviors of Sn-0.75Cu solders and joints in NaCl-Na2SO4 and NaCl-Na2SO4-Na2CO3 simulated soil solutions were investigated compared with those in NaCl solution, aiming to assess the potential risk from the electronic-waste disposed in soil. The leaching kinetics of Sn reveals that the leaching amount of Sn increases with increasing the time. The amount of Sn leached from the joint is the largest in NaCl solution.SO4^2- and CO3^2- inhibit the leaching of Sn from the joints, but accelerate that from the solders. Meanwhile, the corrosion layer of the joint in NaCl solution is more porous, and those immersed in NaCl-Na2SO4 and NaCl-Na2SO4-Na2CO3 solutions are compact. The XRD results indicate that the main corrosion products on the solders and joints surfaces are comprised of tin oxide, tin chloride and tin chloride hydroxide. The potentiodynamic polarization measurements for the solders were discussed in the simulated soil solutions.

Removal of Pb^(2+) and Cd^(2+) by adsorption on clay-solidified grouting curtain for waste landfills

Pb2+ and Cd2+ in leachate were adsorbed on clay-solidified grouting curtain for waste landfills with equilibrium experiment. The cation exchange capacity was determined with ammonium acetate. And the concentration of heavy metal cations in leachate was determined with atomic absorption spectrophotometer. Their equilibrium isotherms were measured, and the experimental isotherm data were analyzed by using Freundlich and Langmuir models. The results show that the adsorption capacities of the heavy metal cations are closely related to the compositions of clay-solidified grouting curtain, and the maximum adsorption appears at the ratio of cement to clay of 2∶4 in the experimental conditions. At their maximum adsorption and pH 5.0, the adsorption capacities of Pb 2+ and Cd 2+ are 16.19mg/g and 1.21mg/g. The competitive adsorption coefficients indicate that the adsorption of clay-solidified grouting curtain for Pb2+ is stronger than that for Cd 2+ . The adsorption process conforms to Freundlich’s model with related coefficient higher than 0.996.

Retention of clay-solidified grouting curtain to Cd^(2+), Pb^(2+) and Hg^(2+) in landfill of municipal solid waste

The effects of components and their ratio of grouts on anti-seepage capability of clay-solidified grouting curtain and its permeability of heavy metal cations were investigated by permeating experiments, using reactive solute transport model to study the permeation of heavy metals (Cd2+, Pb2+ and Hg2+). The study of permeating for different mixture ratios of cement and clay indicates that hydraulic conductivity of clay-solidified grouting curtain with different ratios of solid to liquid or with the same ratio of solid to liquid but with different ratios of cement to clay is changed. The laboratory simulation test results also show that precipitates produced in heavy metal cation migration process in curtain block up water flowing passage which makes the hydraulic conductivity of the solution-permeated curtain decrease with the leakage time. The permeation velocities for different heavy metal cations vary with ionic concentration, exchange capacity and ion radius etc. The test results indicate that the permeation rapidity order of heavy metals cations in clay-solidified grouting curtain is Hg2+>Pb2+ in the same experimental circumstance. In addition, permeability for different mixture ratios and antisepsis capabilities of clay-solidified grouting curtain were studied in tests.

Design of the Metal Precursors Molecular Structures in Impregnating Solutions for Preparation of Efficient Ni Mo/Al_2O_3 Hydrodesulfurization Catalysts

The molecular structures of metal precursors in the impregnating solution were designed so as to prepare efficient Ni Mo/Al_2O_3 hydrodesulfurization(HDS) catalysts. At first, five typical impregnating solutions were designed; the existing metal precursors, such as [Mo4(citrate)2O11]^(4-)-like, [P2Mo18O62]^(6-)-like and [P2Mo5O23]^(6-)-like species in the solutions were confirmed by laser Raman spectroscopy(LRS). The UV-Vis spectra results indicated that the solutions containing both phosphoric acid and citric acid could change the existing form of nickel species. Five corresponding Ni Mo/Al_2O_3 catalysts were prepared by the incipient wetness impregnation method. The LRS analysis results of dried catalysts showed that the above metal precursors could be partly retained on alumina support after impregnation and drying, although the interface reaction between different metal precursors and alumina support unavoidably took place. Then the catalysts were sulfided and characterized by N2 physisorption, TEM and XPS analyses. The results showed that different metal precursors in impregnating solution could mainly result in the difference in both the morphology of(Ni)Mo S2 slabs and the promoting effect of Ni species. The catalyst prepared mainly with [P2Mo5O23]^(6-)-like species used as precursors exhibited worse dispersion of(Ni)Mo S2 slabs and lower ratio of Ni–Mo–S active phases than the one with [Mo4(citrate)2O11]^(4-)-like species. Promisingly, the catalyst prepared with co-existing [Mo4(citrate)2O11]^(4-)-like, [P2Mo18O62]^(6-)-like and [P2Mo5O23]^(6-)-like species showed better hydrodesulfurization activity for 4,6-DMDBT thanks to its more well-dispersed Ni–Mo–S active phases.