碱性硫脲浸金的研究现状与发展趋势

阐述了可能取代氰化浸金的高效、无毒碱性硫脲浸金的研究现状。相比酸性硫脲浸金,碱性硫脲浸金具有溶金选择性好,溶液的再生及净化工序相对容易等优点。阐明了碱性硫脲浸金原理及金在碱性硫脲溶液中的溶解机理,对碱性硫脲溶液中的稳定剂及氧化剂的选择做了详细探讨。最后,指明了碱性硫脲浸金所取得的成果及需要解决的问题,并展望了其发展趋势。     

硫法提金的优化工艺

提出扩散控制硫脲浸金速率表达式，求得浸出平衡时硫脲（Ｔｕ）和三价铁离子浓度之比（ＴＦ）与实验结果［１－３］吻合很好。从试剂最佳匹配入手，以降低试剂总消耗及操作成本为目标而提出了优化工艺。用本工艺处理小秦岭某地区矿，在适当预处理条件下，不加氧化剂，３ｈ内可使金浸出率达９８％以上。主试剂消耗可降到常规硫脲法的１／３到１／５。     

亚硫酸在硫脲浸金中作用的电化学

采用循环伏安曲线和恒电流阶跃法进行了亚硫酸在硫脲浸金中的作用，亚硫酸存在下，硫脲的稳定性增大，溶液中硫脲的有效浓度增大，使金溶解活化能降低。溶解速度明显加快。亚硫酸具有电化学还原，催化硫脲浸金的作用。     

酸性硫脲法提金的研究进展

介绍了在酸性溶液中硫脲浸金的基本原理和主要影响因素,以及硫脲浸金的研究现状和技术改进.同时,对硫脲浸出液中金的提取方法进行了分类介绍,并展望了硫脲提金的发展前景.     

硫脲法提金的优化工艺

提出扩散控制硫脲浸金速率表达式,求得浸出平衡时硫脲(Tu)和三价铁离子浓度之比(TF)与实验结果吻合很好。从试剂最佳匹配入手,以降低试剂总消耗及操作成本为目标而提出了优化工艺。用本工艺处理小秦岭某地区矿,在适当预处理条件下,不加氧化剂,3h内可使金浸出率达98％以上。主试剂消耗可降到常规硫脲法的1/3到1/5。     

低品位铁锰型金银矿的硫脲浸出研究

对铁锰型金银矿采用预先浸锰工艺,使被二氧化锰包裹金银裸露出来,同时降低硫脲浸出金银时的氧化还原电位,有效减少了硫脲消耗量.结果表明,当矿样为200g,经浸锰预处理后,在pH =1.5,电位300mV,亚硫酸钠6g,浸出时间4h的最佳条件下,金、银的浸出率分别为98%、45%,硫脲消耗仅为6kg/t.     

在酸性溶液中用强酸树脂D001回收硫脲金

Ｄ００１大孔强酸型离子交换树脂回收硫脲金的研究表明，溶液中共存离子对金吸附率与其生成硫脲配离子的稳定性有关，吸附有吸热过程，吸附热ΔＨ＾θ＝１０．１９ｋＪ．ｍｏｌ＾－１，表明树脂骨架的位阻是影响吸附平衡的因素。     

难浸金矿石的预处理法

用硫脲法和传统的氰化法处理含砷为9．09％、硫13．07％、金12．25g／t的难浸金矿石,其浸取率分别为72．38％和21．22％。采用氧化焙烧对该矿石进行预处理,可提高其浸取率,在氰化浸出和硫脲浸出中浸取率分别可达80．63％和89．80％。在硫脲浸出中,只需加少量的预处理剂,浸取率即可达90％以上。     

硫氰酸盐浸金研究进展

硫氰酸盐是一种高效、稳定、环保的金矿物浸出剂。讨论了硫氰酸盐浸金机理,从电化学角度阐述了浸出过程发生的反应与可行性,总结了焙烧氧化、加压氧化、化学氧化等预处理方法对硫氰酸盐浸金工艺的影响,归纳了浸出工艺参数浸出剂、氧化剂、p H、杂质离子、硫脲在浸金过程的作用,概括了硫氰酸盐浸出贵液中回收金的方法。从应用、工艺、机理角度概述了硫氰酸盐浸金体系近年来的研究与发展,并提出存在的问题与不足,指出了硫氰酸盐浸金的研究方向。     

基于配位理论的碱性硫脲选择性溶金机理

采用电化学方法研究了金及常见伴生金属元素银、铜、镍、铁在高稳定性碱性溶液中阳极溶解的电化学行为,及碱性硫脲浸金的选择性.结果表明:在最佳溶金电势0.42 V时,金在碱性硫脲溶液的溶解电流密度分别是银、铜、镍和铁的3.4,5.2,27.3和42.6倍;而且碱性硫脲体系进行矿物浸出时金的伴生元素浸出率均小于0.1%,浸金具有显著的选择性.采用配合物的化学键理论、配位理论等分析了碱性硫脲选择性溶金的机理.碱性硫脲溶液中金、银、铜、镍和铁分别以Au(TU) 2,Ag(TU) 3,Cu(TU)2 4,Ni(TU)2 4和Fe(TU)2 6的形式存在,Au(TU) 2中反馈σ-π配键的形成显著增强了其稳定性.配合物Ni(TU)2 4和Fe(TU)2 6中,由于硫脲分子的特殊性,各配位体间硫原子和氮原子上电子云互相排斥,使其稳定性有所降低.而且碱性硫脲溶液中,Ag,Cu,Ni,Fe易于形成致密的硫化物钝化膜,在一定程度上也阻碍了金属的进一步溶解.     

硫脲浸金电化学行为研究

采用循环伏安法(CV)、Tafel曲线和差分脉冲伏安法(DPV)等电化学方法对模拟硫脲浸金体系进行了研究.结果表明,硫脲浓度范围为0.005～0.04 mol/L,浓度增大有利于金的浸出;在Fe3+浓度为0.01～0.08 mol/L范围内,随着Fe3+浓度的增大,金腐蚀电位负移,腐蚀电流变大;适度升温可以提高金的腐蚀...     

LEACHING OF PRECIOUS METALS FROM COMPLEX SULPHIDE ORES——2.DIRECT LEACHING OF Cu SULFIDE CONCENTRATE BY ACIDIC THIOUREA SOLUTIONS

Recovery of gold and silver from a sulphide concentrate by thiourea leaching was investigat-ed.The effects of various parameters on the process,such as oxidants,the initial concentrationof thiourea and acidity in solutions as well as reaction temperature,were systematically exam-ined.From the results it was confirmed that(a)oxidants had no significant influence on the dis-solution of gold and silver at a fixed initial concentration of thiourea;(b)the initial concentra-tion of thiourea and acidity affected the dissolution rate only in the earliest period of leaching;(c)the rate of the process was controlled by reagent diffusion.The optimum operations wereworked out for the thiourea leaching process of the concentrate.     

Recovery of Precious and Base Metals from Waste Printed Circuit Boards Using a Sequential Leaching Procedure

This paper considers the issue of recycling of waste printed circuit boards (WPCBs) containing precious and base metals in appreciable amounts. High-pressure oxidative leaching (HPOL) with dilute sulfuric acid resulted in removal of a significant amount of base metals from a WPCB ash sample obtained by incineration at 800°C. The parameters investigated in the precious metal leaching from WPCB residue after HPOL included the sulfuric acid concentration, thiourea concentration, oxidant concentration, leaching temperature, and leaching time. Recovery of gold, silver, and palladium of 100%, 81%, and 13% from the WPCB residue sample was achieved by thiourea leaching under optimized conditions. The results show that the efficiency of precious metal dissolution from the WPCB sample using thiourea solution depended strongly on the concentration of both thiourea and oxidant.     

从废弃印刷线路板中回收金的试验

试验研究了采用硫脲法有效地从废弃印刷线路板中回收金。试验结果表明，硫脲回收金的主要影响因素有：温度、硫脲质量浓度、Fe^3＋质量分数、浸出时间、硫酸体积分数；合适的浸出条件是：固液比为1：5，浸出温度为35℃，硫脲质量浓度为10g／l，Fe^3＋抖质量分数为0．3％，浸出时间为1h，硫酸体积分数为5％。     

DISSOLUTION THEORY OF GOLD IN ALKALINE THIOUREA SOLUTION(I) Anodic Behavior on Gold in Alkaline Thiourea Solution Containing Na2SO3

Anodic polarization behaviors of gold and its associated elements, e.g., silver, copper, nickel and iron, in the alkaline thiourea solution with and without Na2SO3 were examined. The results showed gold is hardly dissolved in the solution with Na2SO3 because of the passivation of elemental sulfur produced by irreversible decomposition of alkaline thiourea; however, the additive Na2SO3 improves the stability of thiourea in alkaline media, greatly increases anodic current of gold and accelerates the selective dissolution of gold in the alkaline thiourea solution, without changing the passivation states of the associated elements of gold. Also the factors affecting the polarization of gold anode were investigated in detail, and it was found that, the Na2SO3obviously decreases polarization potential of gold and the apparent activation energy of gold dissolution, and the controlling step of the dissolution of gold anode in the alkaline thiourea solution is changed from the anode dissolution reaction to the solute diffusion. The mechanism for accelerated dissolution of gold in the alkaline thiourea solution with Na2SO3 was considered as electrochemical reduction and catalysis, over the Na2SO3 concentration of 0.01 ～0.5 mol/L, at the potential of 0.34～0.44 V.     

Anodic dissolution of gold in alkaline solutions containing thiourea, thiosulfate and sulfite ions

Gld dissolves electrochemically in alkaline solutions containing ligands to form complex ions with gold ion.Therefore,selective leaching of noble metals is expected without dissolution of base metals such as steels,aluminum alloys in scrap treatment.Gold electrodes were investigated using linear sweep voltammetry,EQCM method and potentiostatic eclectrolysis in alkaline solutions containing thiourea,Na2SO3 and Na2S2O3.The solution composition,electrode potential affect gold dissolution rate and current efficiency.The gold dissolved from anode electrode forms complex ions,suspension particles as compound precipitates and deposits on cathode electrode as a metal.Anodic efficiency for gold dissolution is between 10% and 22%.This is caused by the oxidation decomposition of sulfite ions and thiourea.The statbility of the alkaline solution containing these elements was also estimated by capillary electrophoresis technique.     

硫脲碳浆法处理浮选金精矿工艺研究

针对辽宁某地区浮选金精矿采用硫脲碳浆工艺进行研究,并对各种影响因素进行了实验,提出了硫脲碳浆法处理浮选金精矿提金的工艺方案.结果表明,金的浸出率达87.31%,吸附率为98.78%.该项技术具有浸取和吸附时间短,没有环境污染等优点,为工业应用提供技术依据.     

四川丹巴铜炉房金矿床矿石选冶方法研究

通过多次对金矿石的选冶试验研究工作,使金精矿经沸腾焙烧预处理后Au、Ag、Cu、S的浸出回收率均得到显著提高,其中硫脲法Au、Ag、Cu的浸出率分别为99.4%、95.8%、98.0%;氰化法 Au、Ag、Cu的浸出率分别为:99.4%、89.4%、93.3%.最终确定矿石的最佳选冶方案为:原矿破碎→球磨→浮选富集→金、银、铜精矿→沸腾焙烧→烟气制硫酸,焙砂经硫酸浸出萃取电解回收铜后,再经硫脲法回收金银.