二氧化锰对黄铜矿浸出行为的影响

黄铜矿常压浸出存在浸出缓慢等问题。当溶液中存在MnO_2时,由于矿物接触间的原电池效应为黄铜矿的氧化提供更多途径,从而为提高黄铜矿浸出率带来可能。分别研究了在H_2SO_4溶液和H_2SO_4-Fe_2(SO_4)_3溶液中,MnO_2对黄铜矿浸出行为的影响。结果表明,添加MnO_2能够促进黄铜矿的浸出,在浸出过程中,MnO_2迅速分解。黄铜矿在浸出过程中会形成一种缺金属钝化层,这种钝化层附着在黄铜矿表面,阻碍溶液与黄铜矿的接触,阻碍了黄铜矿的浸出。     

锌和镀锌钢的稀土表面改性

通过在Ce(NO_3)_3水溶液中对锌和电镀锌钢进行化学转化(钝化)处理,在试样表面形成了铈转化膜。利用电子探针显微分析(EPMA)、X射线光电子能谱(XPS)和X射线衍射(XRD)等研究了转化膜的形貌、成分和结构,探讨了锌表面铈转化膜的形成机理。在氯化钠溶液中测定了试样的腐蚀率、极化曲线和电化学交流阻抗谱(EIS)等腐蚀性能参量,并与未钝化和普通铬酸盐钝化试样的情况作了对比。结果表明,本实验得到的锌表面稀土转化膜主要是由CeO_2、Ce_2O_3和ZnO组成的复合氧化物膜,铈转化膜的存在阻碍了锌在电化学腐蚀过程中的阴极反应和阳极反应,导致电荷传递电阻增大,腐蚀率降低。在一定条件下,铈转化膜对锌和镀锌钢的肪蚀效果优于铬酸盐转化膜。     

黄铜矿生物浸出中钝化现象研究进展

随着矿产资源的日益贫化，传统的矿物加工及其后续的火法冶炼技术在处理矿物时存在不少弊端，生物浸出技术以其反应温和、对环境友好、能耗低、流程短等优点被各国广泛研究。常温生物堆浸技术业已在硫化铜矿（次生）的开采中实现大规模商业化应用，效果良好。但是，在铜资源主体一黄铜矿的生物浸出研究中，研究者发现常温菌难以获得较高的浸出速率，即所谓的钝化现象，以黄钾铁矾钝化，硫层钝化，多硫化物钝化3种现象最为普遍。为了防止黄铜矿生物浸出过程中钝化现象的产生，提出了Ag^＋催化、Fe^2＋和Cu^2＋催化、嗜热嗜酸菌浸出等有效措施。本文介绍了国内外生物湿法冶金工作者在黄铜矿生物浸出过程中钝化方面的研究进展。     

缅甸某砷质金矿中金的氰化浸出的研究

缅甸某砷铜炭质金矿中的金系难浸矿物之一。直接用碳浆工艺氰化浸出金的浸出率为60%。矿物中的铜在氰化过程中易形成Cu(CN)2 沉淀覆盖在矿物表面上,阻碍金的进一步氰化反应。研究中在金矿石中添加助浸剂后,矿石中的一些矿物与之反应,使金的氰化速度增加,浸出率达到了90%-92%。     

Cu2+催化砷黄铁矿生物氧化试验研究

为解决生物氧化过程中砷黄铁矿表面钝化问题,进行了Cu~(2+)催化砷黄铁矿生物氧化试验研究,分析了生物氧化过程中浸出液铁、砷、pH及电位的变化,并对浸渣进行了XRD和SEM分析。结果表明:适宜的Cu~(2+)质量浓度对砷黄铁矿的生物氧化浸出具有显著的催化作用,可使氧化周期缩短10 d;添加的Cu~(2+)能够进入由雌黄、雄黄形成的钝化层中参与反应,加速钝化物的溶解,使致密的钝化膜产生裂纹,加速砷黄铁矿的氧化。     

初始pH值对ASH-07细菌生长和黄铜矿浸出过程的影响

影响黄铜矿细菌浸出过程的因素很多,重点研究了初始pH值对浸矿细菌ASH-07生长活性、黄铜矿浸出效果和黄铜矿表面氧化膜成分的影响。不同初始pH值条件下细菌培养和黄铜矿浸出实验结果表明,在初始pH=1.2~1.8的条件下,细菌培养24 h后,即开始进入生长平衡期,浓度迅速升高至1.4×108 cell/mL,黄铜矿在浸出6 d后浸出率即达到45.0%左右;氧化膜成分XPS检测实验结果表明,在初始pH值为1.2的条件下,黄铜矿浸出168 h后,矿物表面氧化膜成分中未检测到钝化膜黄钾铁矾。因此,在采用浸矿菌种ASH-07浸出黄铜矿的实验中,最佳的初始pH值约为1.2,pH值低于1.2或高于1.8都不利于黄铜矿的生物浸出。     

细粒层对浸矿表面形貌及钝化的影响

由于矿石粒径配比、表面粗糙度、密度等性质差异,筑堆过程中堆内极易出现矿石颗粒偏析现象.细粒层是导致矿石表面受侵蚀程度不均的关键因素,其严重制约了铜矿资源的高效浸取.为探究细粒层对矿石浸出效果、表面形貌及钝化现象的影响,选取粗颗粒矿石（4 mm < d < 6 mm）与细颗粒矿石（2 mm < d < 4 mm）,开展不同细粒层位置下次生硫化铜矿微生物浸出实验.结合CT扫描与冷场电镜扫描技术等分析手段,从宏、细、微观多层面,探究不同细粒层位置下矿石宏观浸出规律,细观矿石团聚结块,微观表面形貌特征与钝化.结果表明:细粒层导致铜浸出率普遍降低,均低于无细粒层、均匀粗颗粒介质的实验组;不同矿堆位置处细粒层对浸出效果影响不同,细粒层位于顶部的实验组铜浸出效果最优,浸矿60 d铜浸出率达71.3%;同一细粒层不同位置处矿石表面孔裂结构演化程度不一;浸矿60 d后,铜浸出率趋于峰值,矿石团聚结块与钝化现象显著,矿石表面形成以黄钾铁矾、多硫化物、胞外多聚物、硫膜为主的钝化物质层.      

国外信息

国外信息在稀氯化物介质中利用水性臭氧浸出金和钯在室温、低H (<0.1mol/L)和低Cl-浓度条件下可用臭氧从金属废料中浸出金和钯。因Rh和Pt在此条件下稳定,而Cu、Ni、Ag这些杂质元素可在O2/H 及O2/O3/H 体系预处理浸出过程中被除去。在O3/Cl-/H 体系中金和钯溶解为AuCl4-和PdCl4。浸出研究结果表明,浸出反应过程有钝化区间,Au和Pd钝化区间约在<0.01mol/L Cl-和<0.05mol/L Cl-的范围内。在非钝化区间,Au和Pd浸出率受H 和Cl-浓度影响很小。Cl-浓度≤0.01mol/L的情况下,氯气或次氯酸的次生产物可忽略不计。反应动力学似乎受O3(aq)…     

高铁闪锌矿加压浸出过程中Fe的动力学研究

进行了高铁闪锌矿加压浸出过程Fe的动力学研究。考察了温度、压力、始酸浓度、矿样粒度、溶液中Fe^2＋浓度对Fe浸出率的影响。结果表明，在试验条件下，浸出初期Fe的浸出速率受化学反应控制遵循“未反应核减缩型”表面化学反应控制的动力学规律，浸出后期受固膜扩散控制，浸出中期由二者共同控制。     

金浸出过程中电流的作用

金与硫化矿物,氧化矿物及金属接触时,金的浸出受到影响,这主要是由于金与矿物或金属之间电流的作用,以及矿物或金属中物质的扩散在金的表面局部形成了膜的结果。当铜、黄铜矿、黄铁矿与金接触时,它们能引起金的浸出率最大的减少。由于Pb(Ⅱ)离子对金表面的作用,方铅矿能强烈地提高金的溶解率。而当这些Pb(Ⅱ)离子被阻止而不与金接触时,方铅矿阻碍了金的浸出。     

Electrochemical interactions between gold and its associated minerals during cyanidation

Gold occurs in the Witwatersrand gold mines in association with sulphide, oxide and gangue minerals. The leaching behaviour of gold in contact or in association with various minerals depends largely on the galvanic interaction between gold and the mineral, and partially on the formation of a passivating film on the gold surface. Gold in contact with conducting minerals will passivate as a result of the enhanced magnitude of the cathodic current, resulting in decreased gold dissolution rates.Chalcopyrite, pyrite and pyrrhotite cause the largest decrease in the rate of leaching when in contact with gold. Galena strongly enhances the dissolution rate owing to the action of dissolve Pb²⁺ ions on the surface of the gold. When these Pb²⁺ ions are prevented from coming into contact with the gold, galena inhibits the leaching rate. In all experiments the rotating disc of gold passivated so that the rate of dissolution was much slower than that predicted by a mass-transport limiting model.The various films that occur on the surface of the gold and associated minerals, as well as the galvanic interaction (related to electrical conductivity), depend largely on the pretreatment of the ore. Pre-elimination of host minerals from the gold-bearing ore has a marked positive effect on the dissolution rate of gold, and explains the kinetics of reaction on the gold surface to a large extent. From the results presented in this paper on passivation owing to both film formation and galvanic interaction, it can be seen that passivation is not merely a laboratory curiosity, but it can reduce the efficiency of industrial operations and is thus most relevant to practical leaching processes.     

Comparative analysis of the dissolution kinetics of galena in binary solutions of HCl/FeCl3 and HCl/H2O2

A comparative study of the dissolution kinetics of galena ore in binary solutions of FeCl3/HCl and H2O2/HCl has been undertaken.The dissolution kinetics of the galena was found to depend on leachant concentration,reaction temperature,stirring speed,solid-to-liquid ratio,and particle diameter.The dissolution rate of galena ore increases with the increase of leachant concentration,reaction temperature,and stirring speed,while it decreases with the increase of solid-to-liquid ratio and particle diameter.The activation energy (Ea) of 26.5 kJ/mol was obtained for galena ore dissolution in 0.3 M FeCl3/8.06 M HCl,and it suggests the surface diffusion model for the leaching reaction,while the Ea value of 40.6 kJ/mol was obtained for its dissolution in 8.06 M H202/8.06 M HC1,which suggests the surface chemical reaction model for the leaching reaction.Furthermore,the linear relationship between rate constants and the reciprocal of particle radius supports the fact that dissolution is controlled by the surface reaction in the two eases.Finally,the rate of reaction based on the reaction-controUed process has been described by a semiempirical mathematical model.The Arrhenius and reaction constants of 11.023 s-1,1.25×104 and 3.65×102 s-1,8.02×106 were calculated for the 0.3 M FeCl3/8.06 M HCl and 8.06 M H202/8.06 M HCl binary solutions,respectively.     

The kinetics of leaching galena with ferric nitrate

The kinetics of leaching galena with ferric nitrate as oxidant has been studied. Experimental results indicate that the rate of galena dissolution is controlled by surface chemical reaction. Rate is proportional to the square root of the concentration of ferric ion. The addition of more than one mole/liter sodium nitrate decreases reaction rate. With nitrate additions below this concentration, rate either remains constant or is slightly enhanced. An activation energy of 47 kJ/mol was measured, and rate is proportional to the inverse of the initial size of galena particles. These results are explained in terms of mixed electrochemical control. The anodic reaction involves the oxidation of galena to lead ion and elemental sulfur, and the cathodic reaction involves the reduction of ferric ion to ferrous ion.     

碳酸铅物料碱浸试验研究

采用氢氧化钠浸出碳酸铅物料回收铅,试验考察了氢氧化钠浓度、反应温度、时间、液固比对碱浸的影响,确定碱浸的最佳工艺条件：NaOH浓度6 mol/L,液固比10∶1,温度90℃,浸出时间3h。在此条件下,铅的浸出率可达92.77%。     

Reactor for the Oxidation of Galena in Ammonium Carbonate Solution

Anodic behaviour of galena in ammonium carbonate solution and products of anodic reaction resulting in passivation have been studied by electrochemical technologies including ring-disc electrode. The electrochemical dissolution parameters of sulfides have been measured using short circuit cells consisting of massive mineral electrodes. The effects of impurities in galena such as pyrite and pyrrhotite on converting it to lead carbonate have been examined. The conversion can be accelerated by the addition of a little cupric ion to the ammonium carbonate solution. A suitable reactor for the conversion is a propeller-agitated tank without baffles which has been confirmed in large scale experiments with 50 kg ore.     

The dissolution of galena in ferric chloride media

The dissolution of galena (PbS) in ferric chloride-hydrochloric acid media has been investigated over the temperature range 28 to 95 °C and for alkali chloride concentrations from 0 to 4.0 M. Rapid parabolic kinetics were observed under all conditions, together with predominantly (>95 pet) elemental sulfur formation. The leaching rate decreased slightly with increasing FeCl₃ concentrations in the range 0.1 to 2.0 M, and was essentially independent of the concentration of the FeCl₂ reaction product. The rate was relatively insensitive to HCl concentrations <3.0 M, but increased systematically with increasing concentrations of alkali or alkaline earth chlorides. Most significantly, the leaching rate decreased sharply and linearly with increasing initial concentrations of PbCl₂ in the ferric chloride leaching media containing either 0.0 or 3.0 M NaCl. Although the apparent activation energy was in the range 40 to 45 kJ/mol (∼10 kcal/mol), this value was reduced to 16 kJ/mol (3.5 kcal/mol) when the influence of the solubility of lead chloride on the reaction rate was taken into consideration. The experimental results are consistent with rate control by the outward diffusion of the PbCl₂ reaction product through the solution trapped in pores in the constantly thickening elemental sulfur layer formed on the surface of the galena.     

Kinetics of galena leaching in hydrochloric acid-chloride solutions

This article presents a series of studies on the nonoxidative leaching of galena with hydrochloric acid in the presence of a metallic chloride. A systematic study was carried out using a succession of metallic chlorides with cations of different valencies in an attempt to generalize the leaching behavior of these solutions. The reaction order for leaching galena, in terms of the mean ionic activity of HCl, is 3/2 over a wide range of concentration. The addition of soluble chlorides to a HCl solution increases the leaching rate of the galena by augmenting the mean ionic activity of the acid. A reaction order of 3/2 for the mean HCl activity in the solution is maintained for solutions in which the acid concentration is constant and the metallic chloride varies, as well as for the opposite situation. Therefore, the only activity that must figure in the kinetic equation is that of the HCl. The activation energy (58.5 kJ/mole) is independent of the chloride used to increase the activity of the hydrochloric acid. The same is true for the Arrhenius prefactor.     

高碳酸盐砂岩型铀矿石微酸中性浸出性能

为研究微酸中性浸出工艺对高碳酸盐型铀矿石的浸出性能,对某高碳酸盐砂岩型铀矿石进行了静态浸泡试验、多回次氧化浸出试验及柱浸试验。结果表明,高碳酸盐型铀矿应用传统酸法浸出容易产生气堵和CaSO4沉淀,而应用微酸中性浸出虽然浸出强度小,但不容易产生沉淀,应用传统碱性浸出的浸出强度略高于应用微酸中性浸出,但容易产生CaCO3沉淀;应用低浓度H2O2氧化浸出效率低,H2O2主要被矿石中其他还原性物质消耗,高浓度H2O2容易和溶液中的铀反应生成过氧化铀沉淀,而KMnO4氧化浸出效果明显;在柱浸中,微酸浸出浸出率和碱性浸出浸出率分别为49.2%和41.7%,前者主要限制因素是矿柱酸化速率高于矿柱氧化速率,而后者主要限制因素是浸出后期矿层堵塞,渗透性下降。     

The effect of the elemental sulfur reaction product on the leaching of galena in ferric chloride media

The dissolution of galena in 0.3 M FeCl₃-0.3 M HC1 solutions containing 0 to 6 M LiCl was studied at 80 °C, and parabolic kinetics were observed at all LiCl concentrations. The leaching rate increases gradually with increasing LiCl concentrations to ≈4 M LiCl; the presence of >4 M LiCl results in a rapid increase in the leaching rate. The solubility of PbCl₂ in 0.3 M FeCl₃-0.3 M HC1 solutions containing 0 to 6.5 M LiCl was measured over the temperature range of 50 °C to 90 °C. The solubility increases systematically with increasing temperature and LiCl concentration. The parabolic kinetics, coupled with the correlation between the leaching rate and the solubility of PbCl₂, suggest that the dissolution of galena is controlled by the outward diffusion of the PbCl₂ reaction product through the constantly thickening layer of elemental sulfur formed during leaching. This conclusion is also supported by various morphological studies which consistently indicated a thin layer of PbCl₂ between the corroding galena and the porous elemental sulfur reaction product.