5—Br—PADAP光度法同时测定微量钴,镍

本文在酒石酸存在的氨性溶液中,加入焦性没食子酸掩蔽铁,利用EDTA对金属离子络合的差异性,破坏干扰元素与显色剂的络合物而定量保留钴、镍与显色剂的络合物;提高方法的选择性。选择适当的萃取剂增大钴,镍吸收光谱的差异性,结合计算分析消除同一体系中钴、镍相互干扰、实现钴、镍的同时测定。方法用于GSS、GSR系列标样和多种地质试样分析。结果满意。     

应用极谱法测定硫铁矿微量锌过程中钴镍的干扰及消除

<正> 在氢氧化铵-氯化铵底液中,应用极谱法测定锌时,由于钴与锌的半波电位重合(锌半波电位-1.43V,钴半波电位-1.40V),镍与锌的半波电位接近(镍的半波电位为-1.25V),因此,样品中钴镍的存在影响锌的测定,必须消除其干扰。消除干扰可用在被测溶液中加琼胶或改变底液的方法,但这些方法消除钻镍干扰的效果不理想,而且操作较严格不易控制。本实验采用氨三乙酸消除干扰。该方法不但效果好,结果可靠,回收率可达100％;而且操作简便,不影响铜、锌的连测。     

PAR比色法测定矿石中的微量钴

近年来,应用1-2(吡啶偶氮)-间苯二酚钠(简称PAR)作为测定钴的灵敏试剂发表了不少文章.由于PAR与许多金属离子均能生成有色络合物,特别是铁、铜、镍对测定钴有严重干扰,一般都用萃取法、纸色层法来分离干扰元素.我们根据А·И·Бyceb的介绍,用硫代硫酸钠和EDTA掩蔽铜、镍;应用氟化钠消除铁的影响.笔者着重在干扰元素的掩蔽及其消除和显色条件等方面做了一些工作,并应用于不同矿种矿石中微量钻的测定,结果良好.     

某厂电镀车间场地土壤与地下水污染特征

选择某厂电镀车间作为研究区域,采集土壤、地下水、底泥和地表水样品,对样品的pH值、铬、锌、砷、镉、铜、镍、铅和氰化物含量进行了测试,分析了污染物在该区域内的分布特征。结果表明,研究区域土壤主要受到铬、锌、氰化物污染,43%采样点土壤中锌浓度超出土壤环境质量标准三级标准,29%采样点土壤中总铬浓度超出三级标准。55%的采样点地下水受到锌和六价铬污染。电镀车间污水排放口处土壤和地下水样品中均检测到一定浓度的氰化物。电镀车间架空区域下池塘1底泥和附近池塘3底泥及地表水已经受到铬和锌污染。区域内污水池和污泥池铬、锌浓度则严重超标。元素污染物锌、铬和氰化物分别来源于电镀液、电镀后铬酸盐钝化处理及前期采用的氰化物电镀工艺。在分析目前重金属元素污染场地修复技术基础上,建议研究区域采用植物修复技术进行治理。     

SDBS—DAAB体系光度法同时测定矿石中的钴镍

本文在pH8.51NH_3-NN_4Cl缓冲溶液中,考查了Co-DAAB-SDBS和Ni-DAAB-SDBS二体系吸收光谱的特点,系统地研究了两体系在波长610mm处吸光度的加和性,在波长700mm处测定钴络合物的吸光度,镍不干扰的允许范围及其实验条件。提出了在610mm处测定钴镍合量,700mm处测定钴量,差减法计算出镍量,在同一试液中完成钴镍同时测定的一种简便、快速、准确可行的光度测定法。     

新显色剂5—（4—溴苯偶氮）—8—羟基喹啉与钴（Ⅱ）显色反应的？…

研究了新显色剂 5 -(4-溴苯偶氮 ) -8-羟基喹啉 (BAHQ)与钴 (Ⅱ )形成配合物的条件。试验表明 ,该显色剂的离解常数pKa1 ,pKa2 分别为 1.80 ,7.90。BAHQ与钴 (Ⅱ )形成配合物的最大吸收峰在 483nm处。钴 (Ⅱ )浓度在 0～ 16 μg/ 2 5mL范围内符合比耳定律 ,表观摩尔吸光系数ε483 =5 .10× 10 4L·mol- 1 ·cm- 1 ,对比度△λ =88nm。考查了二十多种离子的干扰情况 ,用于测定维生素B1 2 药品中的钴 ,结果满意     

吴宅银铅锌矿床硫化矿石无氰浮选工艺的药剂研究

60年代前,我国在多金属硫化矿浮选方面采用氰化物作为闪锌矿与黄铁矿的抑制剂。但氰化物有剧毒,污染生态环境。同时从工艺上考虑,当浮选矿浆中含有可溶性铜盐或铁盐时,这些盐使氰化钠的作用效力大为降低。矿石中含有金、银时,会因氰化物溶解金、银而损失掉。当矿石中含有可溶于氰化物的次生铜矿物时,生成的氰铜络盐会     

水中氰化物的测定—吡啶吡唑酮分光光度法

氰化物毒性剧烈,水体中含有氰化物对于公共卫生及水生生物的活动、河流的净化等均有重要影响,因此测定水体中氰化物的含量,对于了解水质污染情况有着重要意义。 氰化物的测定,一般采用容量法和比色法常用构比色法有吡啶—盐酸联苯胺法,吡啶—巴比妥酸法等,但由于吡啶有恶嗅,盐酸联苯胺又是致癌物质,因此逐步为吡啶—吡唑酮法代替,但该法仍未消滁吡啶的臭味后又有人改用乙醇作溶剂而吡啶用量     

吡啶——巴比土酸法测定水中氰化物的研究

氰化物主要来源于炼焦、电镀、选矿和金属冶炼等生产过程中的弃水。它在水体中的存在形式是多样的,有的呈简单的盐类,如氰化物的钠、钾盐等,其特点是溶解度大、毒性强;有的呈复盐或铜、锌、铁等氰的络合物存在,它们的化学性质不同毒性也各不相同。 自然界中,地面水氰化物的含量不得超过0.1毫克/升,饮用地下水中不应超过0.01毫克/升,超过指标则有中毒现象发生。为了监测水中氰化物的动态,曾用不同方法进行研究。如氰化物含量在1毫克/升以上时用容量法,小于1毫克/升时则用比色法测定。目前,国内常     

金选矿厂含氰废水中氰化物降解及其环境风险评价

对陕西凤县四方金矿选矿过程中氰化物的迁移转化和降解进行了研究,结果表明,其尾矿库外排含氰废水氰化物浓度达到国家规定的排放标准。在此基础上对氰化物环境风险进行评价,为同类项目尾矿浆和尾矿水环境风险评价提供可信的基础数据。     

Hydrogen Cyanide Accumulation and Transformations in Non-polluted Salt Marsh Sediments

While cyanide is known to be produced by many organisms, including plants, bacteria, algae, fungi and some animals, it is generally thought that high levels of cyanide in aquatic systems require anthropogenic sources. Here, we report accumulation of relatively high levels of cyanide in non-polluted salt marsh sediments (up to 230 μmol kg^?1). Concentrations of free cyanide up to 1.92 μmol L^?1, which are toxic to aquatic life, were detected in the pore-waters. Concentration of total (free and complexed) cyanide in the pore-waters was up to 6.94 μmol L^?1. Free cyanide, which is released to the marsh sediments, is attributed to processes associated with decomposition of cord grass, Spartina alterniflora, roots and possibly from other sources. This cyanide is rapidly complexed with iron and adsorbed on sedimentary organic matter. The ultimate cyanide sink is, however, associated with formation of thiocyanate by reaction with products of sulfide oxidation by Fe(III) minerals, especially polysulfides. The formation of thiocyanate by this pathway detoxifies two poisonous compounds, polysulfides and hydrogen cyanide, preventing release of free hydrogen cyanide from salt marsh sediments into overlying water or air.     

金矿含氰废水中氰化物的降解方法

含氰废水的排放造成严重的环境污染,处理废水中的氰化物具有重要的实际意义,特别是对采用氰化法提金的黄金矿山尤为重要。本文系统介绍了国内外处理含氰废水中氰化物的几种应用效果较好的方法,阐述其原理、工艺流程等,并对其处理效果作了具体比较。     

The distribution and natural degradation of cyanide in goldmine tailings and polluted soil in arid and semiarid areas

Farmlands and rivers have been seriously polluted by cyanide from a goldmine tailings dam that collapsed in early spring of 1995 in Yining County, Xinjiang Autonomous Region of China. The cyanide distribution in the polluted farmland and the abandoned tailings dam was studied, three and 4 years after the accident occurred. The results indicated that natural degradation of cyanide in soils is slower than in natural water bodies. The cyanide transport in the soil section is similar to freely soluble salts. In arid and semiarid areas, cyanide can be highly enriched in the salt crust in which the concentration is even higher than the fresh tailings debris though cyanide has decomposed for 4 years. In the polluted farmland, the sticky layer in the soil section can highly adsorb and enrich cyanide so it can partly prevent cyanide transfer to groundwater. According to the characteristics of cyanide natural degradation in soil, the measures for prevention and cure of soil polluted by goldmine tailing dam collapse have been discussed.     

The preg-robbing of gold and silver by clays during cyanidation under agitation and heap leaching conditions

Laboratory scale leaching tests were carried out in different experimental conditions, with monitoring of gold and silver recovery, the concentration of cyanide used in leaching, solution pH, and precious metal adsorption onto clay. Evidence for the adsorption or re-precipitation of gold from cyanide solutions onto clay minerals is conclusive and indicates that adsorption contributes to the total gold loss from conventional cyanidation. The loss is related to the type of clay, and appears to be affected by the extent of time cyanidation. It was observed that silver adsorption capacity was above 80% and that the degree of adsorption for gold oscillated between 1.68% and 7.49%, depending on the type and characteristics of the evaluated clay.     

Techniques for the Determination of Cyanide in a Process Environment: A Review

The determination of cyanide in various forms is important for industrial processes as well as for environmental investigations and monitoring associated with these processes. The accurate determination of cyanide is difficult for various reasons. Depending on the pH of the solution, cyanide is present both in molecular form (HCN) and ionic form (CN). Furthermore, cyanide is a good complexing reagent and reacts with almost all cations resulting in complexes with widely varying properties, such as stabilities, solubilities and rates of reaction. Cyanide also breaks down in sunlight and air, so that sampling and sample treatment become very important aspects to consider in the methodologies. During the last fifty years the determination of cyanide has been approached from various angles and a myriad of methods has been developed for its determination. This study represents a survey of methods commonly used in industrial laboratories for the analysis of cyanide-containing solutions. An overview of the nomenclature often used for the various forms of cyanides is discussed and the values resulting from a particular analysis will be interpreted. Most common interferences in samples originating from gold processing plants will be discussed.     

Biodegradation of cyanide and evaluation of kinetic models by immobilized cells of <Emphasis Type="Italic">Serratia marcescens</Emphasis> strain AQ07

Immobilized form of Serratia marcescens strain AQ07 was experimented for cyanide biodegradation. Cyanide degradation (200 ppm) was achieved after 24-h incubation. Three parameters were optimized which included gellan gum concentration, beads size, and number of beads. In accordance with one-factor-at-a-time method, cyanide removal was optimum at 0.6% w/v gellan gum gel, 0.3-cm-diameter beads, and 50 beads number. It was able to withstand cyanide toxicity of 800 ppm, which makes it very suitable candidate in cyanide remediation. Beads reusability indicates one-cycle ability. The first cycle removed 96.3%, while the second removed 78.5%. Effects of heavy metals at 1.0 ppm demonstrated that mercury has a considerable effect on bacteria, inhibiting degradation to 61.6%, while other heavy metals have less effect, removing 97–98%. Maximum specific degradation rate of 0.9997 h^?1 was observed at 200 ppm cyanide concentration. Gellan gum was used as the encapsulation matrix. ?-picoline-barbituric acid spectrophotometric analytical method was used to optimize the condition in buffer medium integrated with potassium cyanide via one-factor-at-a-time and response surface method. The range of cyanide concentrations used in this research, specific biodegradation rate was obtained to model the substrate inhibition kinetics. This rate fits to the kinetic models of Teisser, Aiba and Yano, which are utilized to elucidate substrate inhibition on degradation. One-factor-at-a-time approach parameters were adopted because it removes more cyanide compared to response surface methodology modules. The predicted biokinetic constant from this model suggests suitability of the bacteria for use in cyanide treatment of industrial waste effluents.     

某金矿区浅层地下水重金属及氰化物污染评价

以某金矿区浅层地下水为研究对象,通过分析112件浅层地下水样的Hg、Pb、Cd、Cr~(6+)、As、Cu、Zn、CN~-等重金属元素及氰化物的含量特征,初步查明了这8种元素在地下水中的赋存规律。在此基础上,分别利用单项、综合污染指数评价方法对浅层地下水环境质量进行了重金属及氰化物污染评价。结果表明,浅层地下水中除背景元素Cr~(6+)局部区域超标外,受矿业选冶活动影响,双桥河流域中下游段局部区域Hg、Pb、CN~-等元素超标,该结论对浅层地下水资源污染防治具有重要意义。     

Characterization of Kolar gold field mine tailings for cyanide and acid drainage

The gold mining process at Kolar gold field (KGF) mines has generated about 32 million tons of tailings. Gold was extracted from the mined ores using cyanidation technique that involved dissolution of gold in the ore by water soluble alkali metal cyanides (example, sodium cyanide or potassium cyanide). Of the several dumps that received the mine tailings only the Kennedy’s Line dump was active prior to closure of the KGF mines in the year 2000. The Kennedy’s Line dump received sulfide bearing tailings in slurry form that comprised of spent ore and process water bearing soluble alkali metal cyanide. Depending on the pH of the tailing slurry, the free cyanides may exist as aqueous hydrogen cyanide that can escape to the atmosphere as hydrogen cyanide gas or occur as soluble cyanide (CN⁻) ions that can be leached by infiltrating water to the sub-surface environment. Additionally, the presence of pyrite minerals in the Kennedy’s Line dump makes them susceptible to acid drainage. This study examines the potential of gold tailings of Kennedy’s Line dump to release cyanide ions (CN⁻) and acid drainage to the sub-surface environment by performing physico-chemical and leaching tests with tailing samples collected from various depths of the dump, sub-surface soil samples beneath the dump and groundwater samples from vicinity of Kennedy’s Line dump. The chemical mechanisms responsible for the ambient cyanide and pH levels of the tailing dump, sub-surface soil samples and groundwater are also inferred from the laboratory results.     

贵州板其原生金矿石氧化焙烧——氰化浸出的研究

贵州板其原生金矿石属碎屑岩类微细浸染型难选冶矿石,在氰化浸出之前需进行预处理。采用化学分析、Ｘ射线衍射、红外光谱、扫描电镜等方法,研究了矿石经不同温度氧化焙烧后各组成矿物结构变化与金的浸出率变化关系,对焙烧法预处理工艺的微观研究进行了新的探索和尝试。其结果可望有助于矿床成因,构造控矿等方面的微观研究。     

Removal of cyanide from aqueous solutions by plain and metal-impregnated granular activated carbons

In this study, the removal of free cyanide from aqueous solutions by activated carbon was investigated. Effects of metal impregnation (Cu and Ag), aeration, and concentrations of adsorbent and cyanide on the rate and extent of the removal of cyanide were studied. The results have shown that the capacity of activated carbon for the removal of cyanide can be significantly improved (up to 6.3-fold) via impregnation of activated carbon with metals such as copper and silver. Silver-impregnated activated carbon was found to be the most effective at the reduction of cyanide level in solution. This appeared to be coupled with its comparatively high metal content after impregnation process where silver (5.07%) could be more readily loaded on activated carbon than copper (0.43%). Kinetics and equilibrium data for cyanide removal by plain and metal-impregnated activated carbons were determined to be consistent with the pseudo second-order kinetics and the Langmuir adsorption isotherms, respectively. Aeration (0.27 l/min) was found to exert a profound effect on the process leading to a 5.5–49.1% enhancement in the performances of plain and metal-impregnated activated carbons. This enhancement could be attributed to the increase in the availability of active sites on activated carbon for adsorption and the catalytic oxidising activity of activated carbon in the presence of oxygen. Practical limiting capacity of plain, copper- and silver-impregnated activated carbons for the removal of cyanide were experimentally determined to be 19.7, 22.4 and 29.6 mg/g, respectively.