硫离子、亚硫酸根和硫代硫酸根分析方法的研究

硫铵母液中硫离子,亚硫酸根离子,硫代硫酸根离子共存。这三种离子都能与碘发生氧化还原反应,本文主要阐述了如何将母液中的三种离子区分开来,并进行准确定量测定。     

硫代硫酸盐提金理论研究：金的阳极溶解

本文研究了金在硫代硫酸盐溶液中的阳极溶解行为,结果表明,在氨性硫代硫酸盐溶液中金的阳极溶解机理为NH_3优先扩散至金粒表面与金离子络合,生成的金氨络离子进入溶液后被S_2O_3~(2-)取代,形成更稳定的金硫代硫酸根络离子。试验研究及理论分析证实和支持了这一机理。     

间接碘量法测定氧化铝生产流程样品铝酸钠溶液中硫离子、硫代硫酸根和亚硫酸根

通过控制不同的条件,先在铝酸钠溶液中加入过量的碘,使碘分别与铝酸钠溶液中的硫离子、硫代硫酸根和亚硫酸根反应,再用硫代硫酸根标准溶液返滴定过量的碘,最后,通过差减法得到硫离子、硫代硫酸根和亚硫酸根各自的含量,从而建立了间接碘量法测定铝酸钠溶液中硫离子、硫代硫酸根和亚硫酸根的方法。同时,运用碘酸钾与碘化钾在中性条件下不发生化学反应而在酸性条件下可反应生成碘的特性,在中性条件下使用基准碘酸钾与过量碘化钾配制了碘标准溶液,在实际测试时,只需通过向样品溶液加酸及碘标准溶液即可得到定量的碘,避免了由碘性状不稳定所带来的含量变化问题。将实验方法应用于不同生产流程中铝酸钠溶液(高压溶出液、粗液、种分母液)进行测定,5次平行测定硫离子、硫代硫酸根和亚硫酸根结果的相对标准偏差分别为0.68%～0.82%、0.26%～0.44%、0.38%～0.74%。按照实验方法对3种合成铝酸钠标准溶液中硫离子、硫代硫酸根和亚硫酸根进行测定,测定值均和理论值相符。     

铜氨溶液中亚硫酸根硫代硫酸根的氧化

在铜离子存在下，氨性溶液中亚硫酸根，硫代硫酸根的氧化，可分为起始阶段Ｖ１和后续阶段Ｖ２。Ｖ１比Ｖ２大两数量级。溶液中加入硫本乡既能抑制ＳＯ＾２－的氧化，又能抑制Ｓ２Ｏ３＾２－的氧化。为了减少Ｓ２Ｏ３＾２－的氧化，在硫代硫酸盐浸金系统中应尽量采用较低的铜浓度，较小的进氧量，较低的浸取温度，较短的浸取时间。     

超声波对硫代硫酸盐浸金体系稳定性的影响

探索了超声波作用对铜氨硫代硫酸钠浸金体系稳定性的影响。考察了不同浸出时间、温度、超声波功率、pH和氨水浓度条件下,浸金体系内硫代硫酸根离子浓度以及Cu(NH_3)_4~(2+)络合离子浓度变化规律。结果表明,超声波作用使硫代硫酸盐浸金体系稳定性有所降低,一定条件下可显著促进硫代硫酸根离子和Cu(NH_3)_4~(2+)络合离子浓度的降低。金矿石浸出试验表明,当Na_2S_2O_3浓度为0.1mol/L、CuSO_4浓度为0.03mol/L、NH_3·H_2O浓度为0.45mol/L时,超声波作用能够显著提高浸金率,在较低浸出温度下引入超声波辅助浸出就能达到常规较高温度下的浸出效果。本研究为降低硫代硫酸盐浸金反应的温度开辟了新的路径。     

含铜络离子对硫代硫酸盐法提金过程影响

硫代硫酸盐法是一种绿色、高效的提金方法,含铜氨性硫代硫酸盐体系是常见的硫代硫酸盐提金体系。该体系中,铜离子可与氨和硫代硫酸根离子分别形成四氨合铜络离子和硫代硫酸铜络离子,这些络离子不仅在金矿物溶解过程中起着至关重要的作用,同时也会对回收过程中金的沉积与吸附产生一定影响。介绍了硫代硫酸盐法提金机理及含铜络离子在提金过程中的作用,并分析了几种常见提金方法中含铜络离子对金回收过程的影响。同时,指出了从硫代硫酸盐贵液中回收金的发展方向。     

铜-乙二胺-硫代硫酸盐浸金体系中硫代硫酸盐消耗研究

硫代硫酸盐浸金体系是一种绿色浸金体系,与传统的铜氨体系相比,铜-乙二胺体系展现出更好的稳定性。在模拟浸金的基础上,分别考察了pH、铜离子浓度、乙二胺浓度、硫代硫酸盐浓度等因素对硫代硫酸盐消耗率的影响。结果表明:pH值为9~10时,硫代硫酸盐消耗率较小,约为17%~18%;乙二胺浓度为0.01~0.04 mol/L时,硫代硫酸盐消耗率呈下降趋势;铜离子浓度为0.002~0.010 mol/L时,硫代硫酸盐消耗率逐渐增大;硫代硫酸盐浓度越低,其消耗率越高。研究结果可为铜-乙二胺-硫代硫酸盐浸金工艺提供一定的理论依据。     

硫代硫酸盐浸金各因素影响研究现状

硫代硫酸盐浸金技术是非氰浸金技术研发的重点,特别是铜-氨-硫代硫酸盐体系因浸出速率快、环保、碱性腐蚀性小和适应含砷含碳难处理矿石等优势而受到了持续关注。探明不同种类硫代硫酸盐的作用、常见载金矿物的吸附、矿物的催化分解作用、矿物的离子释放影响、重金属离子的溶解及不同阴离子对反应历程、浸出过程和浸金效果的影响,能更好地为硫代硫酸盐浸金的应用发展指明方向。研究表明,硫代硫酸盐浸出过程中,硫代硫酸盐会因阳离子不同而适用于不同类型的矿物,而不同的载金矿物也会因自身的特性而呈现出不同的吸附、溶解和催化分解能力。同时,浸出体系中矿物溶解释放的阳离子浓度和形式的不同会对体系产生有利或不利的影响。由于药剂的添加和硫代硫酸根的分解等因素引入的阴离子会对体系产生完全不同的作用。为了消除干扰因素对浸出体系造成的影响,可以通过添加磷酸盐、EDTA和CMC等添加剂改善浸出过程和效果。     

钨酸钠溶液中硫代钼酸根离子生成条件的研究

在现今所研究的钨钼萃取分离方法中,有一种是借硫代钼酸根离子与钨酸根离子在弱碱性介质中的可萃性的差异,硫代钼酸根子离优先萃入有机相,得以与钨分离。钨酸钠溶液中MoO_4~(2-)离子向硫代钼酸根离子转化的彻底性是该方法除钼的前提条件,研究硫代钼酸根离子生成的工艺参数具有极其重要的意义。     

硫代硫酸盐-EDTA-铜离子浸金体系电化学研究

硫代硫酸盐-乙二胺四乙酸(EDTA)-铜离子浸金体系采用乙二胺四乙酸(EDTA)代替氨水作为铜的络合剂,所得到的络合物具有稳定性好,电极电势较低等优点,从理论上可以作为金的浸出液用于金的提取。本文采用Tafel曲线,开路电势,循环伏安这3种方法探究了硫代硫酸盐对金的腐蚀的影响,考查了铜离子浓度对硫代硫酸盐电化学行为影响以及硫代硫酸盐循环伏安行为,结果表明:硫代硫酸盐浓度的增加使金的腐蚀更加容易,超过0.10 mol·L~(-1)后,由于硫代硫酸盐浓度的增加,其在金电极表面的产物导致电极的钝化,从而导致金的腐蚀变得困难;随着铜离子浓度的增加,硫代硫酸盐还原电位负移,峰电流增加,说明在该条件下,硫代硫酸盐更加容易被消耗;循环伏安表明峰电流与扫描速度平方根成直线关系,属于扩散控制,这个过程中,硫代硫酸盐还原电子转移数约为1,硫代硫酸盐循环伏安行为表明lnI_p与1/T呈良好的线性关系,其活化能E_a=5.498 kJ·moL~(-1),说明为浓差极化所致。     

Kinetic model for anodic oxidation of gold in thiosulfate media based on the adsorption of MS2O3− ion-pair

It has been the general practice amongst researchers to use the molar concentration of thiosulfate salts to be the same as that of S₂O₃²⁻ ions involved in various equilibrium or rate expressions for interpreting gold oxidation kinetics. However, chemical speciation analysis based on the association of thiosulfate ion with monovalent cations (ion-pair formation) shows that the concentration of free S₂O₃²⁻ ions is lower than that of associated MS₂O₃⁻ ions (M=Na, K, NH₄). Analysis of literature data on electrochemical oxidation rates of gold in non-ammoniacal alkaline sodium thiosulfate solutions based on the adsorption of NaS₂O₃⁻ shows that the rate constant for gold oxidation is 4.2×10⁻⁴ mol m⁻² s⁻¹.     

硫代硫酸盐提金理论研究：阴极过程及浸金机理

本文研究了金在硫代硫酸盐溶液中溶解的阴极机理,结果表明,在含铜氨的溶液中,二价铜氨络离子在金表面直接还原,生成的一价铜氨络离子进入溶液后,迅速被氧化再生为二价铜氨络离子,后者又到金粒表面上还原。根据硫代硫酸盐浸金阳、阴极过程电化学研究的结果,提出了氨性硫代硫酸盐浸金的电化学—催化机理及模型。从本质上揭露了铜、氨在硫代硫酸盐浸金过程中的作用,填补了硫代硫酸盐提金理论的空白。     

强化硫代硫酸盐浸金研究

在硫代硫酸盐－亚硫酸盐－铜氨络离子浸金体系中,加入３￣４ｇ／Ｌ强化剂ＣＯＰＸ,可溶解金粒上附着的氧化物及硫化物钝化膜,提高浸金率１０％￣３０％。本法可用于含铜难处理金精矿及ＣＧＡ载金聚团中金的解脱。     

Antioxidants for prevention of methionine oxidation in recombinant monoclonal antibody HER2

Recombinant humanized monoclonal antibody HER2, rhuMAb HER2, in liquid formulations undergoes oxidation when exposed to intense light and elevated temperatures (30 & 40 degrees C). Met-255 in the heavy chain of the Fc region of the antibody is the primary site of oxidation. Met-431 of the Fc fragment can also be oxidized under extreme conditions. The amount of oxidation was determined by cleaving the Fab and Fc fragments by papain digestion, and the oxidized Fc fragment was detected by hydrophobic interaction chromatography. Oxidation of rhuMAb HER2 was also formulation dependent. The presence of NaCl in the rhuMAb HER2 formulation caused an increase in oxidation at higher temperatures after contact with stainless steel containers or stainless steel components in the filling process. The corrosion of stainless steel by chloride ions at the low pH of the formulation buffer generated iron ions that catalyzed methionine oxidation in rhuMAb HER2. Temperature-induced oxidation of rhuMAb HER2 occurred by the formation of free radicals, and light-induced oxidation of rhuMAb HER2 occurred via single oxygen pathway. Antioxidants, such as methionine, sodium thiosulfate, catalase, or platinum, prevented Met oxidation in rhuMAb HER2, presumably as free radicals or oxygen scavengers. The minimum effective levels (molar ratios of protein to antioxidant) required to inhibit temperature-induced oxidation were 1:5 and 1:25 for methionine and thiosulfate, respectively. A thiosulfate adduct of rhuMAb HER2 was observed by cation-exchange chromatography. These studies demonstrate that stoichiometric amounts of methionine and thiosulfate are sufficient to eliminate temperature-induced oxidation of rhuMAb HER2 caused by free radicals that were generated by the presence of metal ion and peroxide impurities in the formulation.     

硫代硫酸盐浸金理论及实践

对硫代硫酸盐的性质、浸金机理、浸金中的影响因素及硫代硫酸盐浸金实践进行了研究，指出了硫代硫酸盐是最具工业应用前景的非氰浸金试剂之一。     

硫代硫酸盐提金理论研究——浸金的化学及热力系原理

本文详细讨论了硫代硫酸盐浸金的化学及热力学原理。列出了硫代硫酸盐提金体系可能发生的化学反应,有关物质的标准生成自由能、有关电极反应的标准电极电位及络离子的稳定常数。为研究硫代硫酸盐法提金提供了基本的物理化学基础。     

A Review of Ammoniacal Thiosulfate Leaching of Gold: An Update Useful for Further Research in Non-cyanide Gold Lixiviants

This literature review provides an update of ammoniacal thiosulfate as a potential lixiviant of gold, the history of thiosulfate leaching and recent progress on thiosulfate leaching of gold, as well as the production, oxidation, and stabilization of thiosulfate. The leaching results of different types of gold ores including oxide, sulfide, carbonaceous, and refractory ores/concentrates and the fundamentals relevant to the oxidation of pure gold are summarized. The factors affecting gold leaching such as pH, temperature, and oxidants in leaching solutions, reagent concentrations, and foreign ions are presented to update the current understanding on gold dissolution in a Cu(II)-NH₃-S₂O₃^2-system.     

A kinetic study that compares the leaching of gold in the cyanide, thiosulfate, and chloride systems

Due to the increasing environmental and public concerns over cyanidation, there has been a large amount of research into viable alternative lixiviants. This article presents a detailed kinetic study of gold leaching in cyanide, ammonia/thiosulfate, and chloride/hypochlorite solutions. The gold leach rates were measured using a rotating electrochemical quartz crystal microbalance (REQCM). This instrument allows the mass of a gold sample to be measured in situ, with a sensitivity of less than 10 ng. It will be shown that for the cyanide system, the leach rate of a gold/silver alloy is substantially higher than that of pure gold; for the gold/silver alloy, the reaction is diffusion controlled. For the thiosulfate system, reaction rates which are substantially higher than those for cyanide can be achieved with freshly prepared solutions containing copper(II), although the leach rate decreases as the copper(II) reacts with thiosulfate. A steady-state copper(II) concentration is obtained once the rate of copper(II) reduction by thiosulfate matches the rate of copper(I) oxidation by oxygen; at these steady-state concentrations of copper(II), the leach rates are slower than those obtained for cyanide. It will also be shown that reaction rates similar to the cyanide system can be readily achieved in chloride media at pH 3 with 2.5 mM hypochlorous acid; under these conditions, the reaction is limited by the diffusion of HClO.     

Antidotal efficacy of alpha-ketoglutaric acid and sodium thiosulfate in cyanide poisoning

Alpha-ketoglutaric acid and sodium thiosulfate antagonize the toxic effects of cyanide. The present study was performed to test whether a synergistic effect may occur. The alpha-ketoglutaric acid/sodium thiosulfate solutions were injected intraperitoneally into mice prior to exposure to hydrogen cyanide (HCN) in a dynamic inhalation chamber or preceding an intraperitoneal injection of sodium cyanide (NaCN). All lethal concentration (LCT) and lethal dose (LD) values were determined after a period of 24 h. Alpha-ketoglutaric acid alone provided no protection at 250 mg/kg when challenged with HCN. Sodium thiosulfate 500 mg/kg provided a 5% protection. However, when these doses of alpha-ketoglutaric acid and sodium thiosulfate were combined, protection was increased by 18%. Alpha-ketoglutaric acid (250 mg/kg) and sodium thiosulfate (1000 mg/kg) provided an additional 48% protection against a LCT88 of HCN. A single dose of alpha-ketoglutaric acid (500 mg/kg) and sodium thiosulfate (1000 mg/kg) solutions afforded a 70% increase in survivability of the exposed animals. When mice were injected ip with 100 mg/kg of alpha-ketoglutaric acid 15 min prior to the injection of 5.5 mg/kg (LD50) of NaCN, the lethality was reduced to an LD30. Two hundred mg/kg alpha-ketoglutaric acid, challenged with the same dose of NaCN, reduced the lethality to 23%. When mice were challenged with 6.0 mg/kg of NaCN (LD70) pretreated with 100 mg/kg of alpha-ketoglutaric acid or 200 mg/kg of sodium thiosulfate, the LD was not altered in the former but reduced to an LD15 in the latter. At higher doses of sodium thiosulfate (500 mg/kg), an LD60 occurred at 13.6 mg/kg NaCN (2.5 x LD50).(ABSTRACT TRUNCATED AT 250 WORDS)