难浸氰化尾渣浮选精矿的常温常压碱浸预处理

某氰化尾渣浮选精矿采用超细磨-氰化方法处理,在＜37μm占99.5%的磨矿细度下浸出24h,金的浸出率仅有1.80 %,极难浸出.采用常温常压碱浸强化预氧化工艺处理后,在NaCN用量6kg/t、氰化时间24h的条件下,金的浸出回收率提高到85.82%,炭吸附率99.66%.     

多硫化物微细粒浸染型金矿回收金试验研究

为回收某含碳高砷高硫微细粒复杂难处金矿中的金,分别开展了全泥氰化浸出、浮选、焙烧、酸浸试验研究。结果表明,采用常规的全泥氰化浸出和浮选工艺,对金的回收效果均不好。采用“焙烧-全泥氰化浸出”工艺,受矿石焙烧后新产生的金属氧化物包裹金的影响,金浸出率仅有72.25%。经研究发现,采用酸溶方法,对焙砂进行加温酸浸预处理,可有效打开其被包裹的金,从而提高对金的回收。采用矿石“焙烧-酸浸-水洗-碱浸-全泥氰化浸出”联合工艺,金浸出率88.52%。     

难处理高砷金矿的细菌氧化-提金研究

采用经过驯化的HQ0211菌对高砷金矿进行氧化预处理-氰化提金实验研究.该矿石含金128.5 g/t,含砷16.84%(质量分数,余同),含硫21.72%,含铁26.62%,氰化浸出率只有29.35%,是典型的高砷难处理矿.经过细菌氧化预处理,金矿脱砷率达到96.2%,失重率达到43.9%.矿石的金氰化浸出率由原来的29.35%提高到92.57%,效果十分显著.     

硫精矿中难选金银焙烧浸出研究

某高金硫精矿全泥氰化时金和银的浸出率低,一段焙烧预处理会造成金和银的二次包裹。实验结果显示,二段焙烧效果优于一段焙烧效果,能降低氧化铁的烧结程度,减少铁氧化物对金、银的包裹,金、银浸出率分别为79.86%、68.13%。添加剂实验结果表明,焙烧过程加入NaOH,银浸出率大幅提高;加入CaO有利于金的浸出;加入KMnO4能降低焙砂硫品位。以NaOH、CaO、KMnO4为组合焙烧添加剂,金、银浸出率提高至87.43%、85.86%。扫描电镜观察到,加入组合焙烧添加剂有利于焙砂孔隙度的提高,氰化尾渣表面腐蚀较为严重,有利于浸出剂与金、银的接触。 关健词:含金硫精矿;全泥氰化;二段焙烧;焙烧添加剂     

湖南某高砷难处理金精矿的细菌氧化-氰化提金实验研究

湖南某高砷金精矿属于难处理矿石,含砷11.28%,含金66.18g/t,金的直接浸出率仅为21.91%.通过该样品5%、10%、15%、20%矿浆浓度的细菌氧化试验,发现金精矿砷的氧化率达到93%以上.细菌氧化渣的金浸出率随着矿浆浓度的增大而降低,5%矿浆浓度下细菌氧化渣的金浸出率为93.15%;10%矿浆浓度下细菌氧化渣的金浸出率为92.46%;15%矿浆浓度下细菌氧化渣的金浸出率为90.50%;20%矿浆浓度下细菌氧化渣的金浸出率为87.58%,比未经处理时金的直接氰化浸出率21.91%有了很大的提高,预处理效果很好.     

焙烧氰化尾渣提金工艺研究现状

焙烧氧化过程中铁物相出现熔融或再结晶,对金造成二次包裹,使焙砂中部分金仍难以浸出,导致焙烧氰化尾渣金品位较高。破坏尾渣中铁氧化物对金的包裹可提高金的浸出率。综述了焙烧氰化尾渣主要提金工艺,包括直接酸溶法、还原焙烧法、氯化法、炼铁-电解法、硫酸熟化法和硫脲法等。直接酸溶工艺简单,金浸出效果较差;还原焙烧法金浸出率高,但工艺复杂、能耗大;氯化焙烧法对矿石适应性强,可综合回收有价金属,但基建及维护费用高;炼铁-电解法在富集金的同时可获得纯铁产品,对矿石有较高的要求;硫酸熟化法显著提高金银浸出率,与直接酸溶法相比,所需更高的温度与酸度;硫脲法反应速率快、选择性好,但生产成本较高。 关健词:有色金属冶金;氰化尾渣;铁氧化物;包裹金;提金     

高岭石对氰化浸金的影响及助浸研究

采用电化学实验研究了在氰化浸金过程中常见矿物高岭石对金溶解速率及对溶液中金的吸附效果的影响。结果表明,高岭石的存在会使金的溶解速率加快,随着高岭石粒度逐渐降低金的溶解速率提高,且高岭石对溶液中金的吸附率增加。氰化浸出实验结果表明,高岭石存在时金的浸出率由93.21%降低到91.76%,采用柠檬酸三钠、过氧化镁和十二烷基硫酸钠助浸时,金浸出率升高至94.42%。能谱分析(EDS)发现浸出物中高岭石表面有金元素存在,表明高岭石会吸附溶液中的金。红外光谱分析和密度泛函理论计算表明,高岭石与金发生化学吸附作用,氢原子为高岭石的活性位点,C6H5O7^3-会优先吸附于高岭石(001)表面,加入助浸剂可降低高岭石与金的吸附强度,提高金的浸出率。     

难冶金精矿烟尘中铁砷碳的脱除对氰化浸金的影响

以难冶金精矿烟尘为原料,研究了氢氧化钠浸出、硫酸浸出以及硫酸与氢氧化钠联合浸出对烟尘中砷、铁和碳脱除及氰化浸金的影响。结果表明:在氢氧化钠浓度为6mol/L时,砷、碳脱除率分别为99.66%和60.63%,金浸出率为58.90%,较直接氰化浸出仅提高4.60%,砷的有效去除不能有效提高金的浸出率。在硫酸质量分数为15%时,铁、砷和碳脱除率分别为33.65%、80.38%和12.59%,金的浸出率为80.40%,与氢氧化钠浸出相比,硫酸浸出解离铁能有效提高金的浸出率。烟尘分别经过质量分数为15%硫酸浸出后氰化浸金,两次2 mol/L氢氧化钠浸出和氰化浸金后,烟尘中铁、砷和碳的总脱除率分别为33.65%、95.63%和79.60%,渣率为80.33%。此时,金的总浸出率为91.90%,氰化渣中金的含量为3.31g/t。与烟尘直接氰化浸出相比金的浸出率提高37.60%。     

难浸砷金精矿的碱性常温常压预氧化

本文提供了1种难浸金精矿的湿法预氧化新工艺,它包括细磨、强化碱浸预氧化、氰化和炭吸附。在螺旋搅拌式塔式磨浸机中,先将目的难浸金精矿细磨至98%<37μm,然后在40%的矿浆质量浓度、11℃的环境温度和0.1MPa的环境压力下强化碱浸24h,NaOH的消耗量为88kg/t矿,仅为相同氧化率条件下将砷硫氧化成砷酸盐和硫酸盐所需理论碱耗量的30%。预氧化完成后经36h的氰化浸出和炭吸附,金的浸出率从预氧化前的24.6%提高到95.4%,金的吸附率99.2%,NaCN的消耗4kg/t矿。整个提金工艺的成本约300元/t矿。     

高硫砷金矿焙砂的硫酸熟化法预处理

基于氧化铁与硫酸反应的热力学原理,采用硫酸熟化-水浸法对高硫高砷金精矿氧化焙砂进行预处理,以脱除铁氧化物,破坏其对金的包裹,提高金浸出率。结果表明,在适宜的硫酸含量下,赤铁矿与硫酸反应的产物硫酸铁可转化为板铁矾HFe(SO4)2·4H2O晶体,降低了产物浓度,从而使赤铁矿继续溶解,提高了铁脱除率;适当升高温度可促进扩散的进行,从而使铁的脱除更加彻底。焙砂的氰化浸金率在脱除铁氧化物后显著提高。对于某铁含量为31.25%(质量分数)金含量为84.27 g/t的焙砂,当熟化条件为硫酸含量75%、硫酸过剩系数1.4、熟化温度250℃、熟化时间1 h时,焙砂中残余铁含量降至7.23%,此时金浸出率可达97.51%。     

Co-intensification of cyanide leaching gold by mercury ions and oxidant

The effects of mercury ions on gold cyanidation were studied. The results show that under low cyanide concentration, gold cyanide process is controlled by CN^? transfer, while at higher cyanide concentration, there forms passivation on gold surface. Therefore, chemical oxidation of gold in cyanide solution of higher concentration is controlled by surface reaction. Small quantity of additions of mercury ions bring about great increases in anodic gold dissolution rate, decreases the passivation and reduces the equilibrium activated energy. In addition, they also markedly change the effect pattern of cyanide concentration. Mercury ions show positive effects on cathodic reduction of oxygen and raise the rate of electrochemical step of the cathodic reduction of oxygen. Addition of a certain amount of hydrogen peroxide is confirmed to be an effective way for intensification of cathodic process on gold electrode. Active potential range and current peak on anodic dissolution are enlarged when being co-intensified with Hg²⁺ and hydrogen peroxide. Co-intensifying effect may be obtained and gold leaching rate is considerably increased on cyanide leaching of gold from gold concentrates.     

Co-intensification of gold leaching with heavy metals and hydrogen peroxide

Co-intensification was researched to accelerate gold leaching with regards to its electrochemical nature by using anodic intensifiers of heavy metal ions (Pb2+, Bi3+, Tl+, Hg2+ and Ag+) on the basis of hydrogen peroxide assistant leaching on three different types of materials which were classified as a refractory sulphide gold concentrate, an easily leachable sulphide gold concentrate, and a low grade oxide gold ore according to their leaching characteristics. The results showed that, favorable co-intensification effects on the three materials were obtained and leaching time of gold was effectively shortened to no longer than 12 h from 16 to 24 h for hydrogen peroxide assistant leaching. For the five tested heavy metal ions, Bi3+and Tl+ presented co-intensifying effect on all the three materials, and Hg2+ caused co-intensifying effect on both refractory and easily leachable sulphide gold concentrates, and Pb2+ and Ag+ only had co-intensifying effect on the easily leachable sulphide gold concentrate.     

Applications of mixed potential model in leaching of gold

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Characterization of refractory behaviour of complex gold/silver ore by diagnostic leaching

The amenability of a refractory ore to the extraction of gold and silver by cyanide leaching was investigated. Diagnostic leaching tests were also performed to shed light on the refractory characteristics of ore. The leaching tests show that the extraction of gold and silver is consistently low, i.e. ≤47% and ≤19.2%, respectively, over a leaching period of 24 h. Even fine grinding (e.g. ＜38 μm) does not improve the recovery of gold and silver. Diagnostic leaching approach provides information into the cause of the refractoriness of the ore. The findings suggest that the refractoriness is induced by the dissemination and encapsulation of the very fine gold and silver particles largely in the carbonates, oxides and sulfides and, to a small extent, with silicates present in the ore matrix. These findings highlight the practical importance of diagnostic leaching for the understanding of the refractory characteristic of such an ore and for the identification of possible pretreatment options to overcome its refractoriness prior to cyanide leaching.     

铜-氨-硫代硫酸盐体系金溶出影响因素的电化学研究

铜-氨-硫代硫酸盐浸金体系中，金的溶出本质上是电化学过程。采用交流阻抗和Tafel曲线分析硫代硫酸盐、铜离子、氨浓度对金的溶出影响。结果表明:在金的溶出过程中，硫代硫酸盐和铜离子可能会导致钝化，尤其使铜离子浓度增大会导致钝化加剧，这种钝化会交替出现；氨水不会导致钝化；对金溶出速率的影响，硫代硫酸盐最大，铜离子最为复杂，氨影响相对最小。     

Pressure leaching of metals from waste printed circuit boards using sulfuric acid

Printed circuit boards (PCBs) are essential components of electronic equipments which contain various metallic values. This paper reports a hydrometallurgical recycling process for waste PCBs, which consists of the novel pretreatment consisting of organic swelling of PCBs followed by sulfuric acid leaching of metals from waste PCBs. To recycle the waste PCBs, experiments were carried out for the recovery of copper from the crushed and organic swelled materials of waste PCBs using sulfuric acid leaching in presence of hydrogen peroxide under atmospheric and pressure condition. The leaching of PCBs at 90°C, pulp density 100 g/L under atmospheric condition, using 6M sulfuric acid resulted in the dissolution of a minor amount of copper due to the presence of plastic coating on the surface of metallic layers. On the other hand, when the liberated metal sheets from organic swelled PCBs were treated with dilute sulfuric acid of concentration 2M along with hydrogen peroxide in an autoclave under oxygen atmosphere, the percentage recovery of copper was found to increase from 59.63% to 97.01% with an increase in hydrogen peroxide concentration from 5 to 15% (v/v) keeping constant pulp density 30 g/L.     

The Effect of Oxygen on Copper Dissolution during Cathodic Polarization

The effect of oxygen on the anomalous dissolution of copper in acidic chloride media is studied. An increase in the copper corrosion rate during cathodic polarization in the potential range from –0.4 to –0.7 V is attributed to stirring of the near-electrode layer by evolving hydrogen bubbles. An addition of surface-active tetrabutylammonium iodide shifts the overpotential of hydrogen evolution and eliminates this effect. The copper dissolution rate during cathodic polarization is shown to be directly proportional to the reduction rate of dissolved oxygen. It is shown experimentally that H₂O₂ does not affect the dissolution rate of copper during cathodic polarization. The latter fact makes it possible to assume that oxygen reduction stages, which involve hydrogen peroxide, do not affect the anomalous dissolution of copper.     

次氯酸钠浸金电化学及难浸金矿浸出实验研究

用恒电位仪测定了不同次氯酸钠浓度和pH的条件下金阳极溶解极化曲线,拟合得到自腐蚀电位(Ecorr)、自腐蚀电流密度(Icorr)以及线性极化电阻(Rp),并进行难浸金矿的搅拌浸出验证实验。结果表明,在不同浓度条件下金腐蚀速率先增大后减小,在浓度0.75 mol/L时金阳极开始钝化,浸出实验结果与电化学研究结果一致;不同pH实验条件下金的腐蚀速率随pH增加而逐渐增大,但pH超过12后浸出率稍有下降,浸金结果与电化学研究结论略有不同。