从铜镉渣中析出铜锌镉的氧化氨浸工艺

针对传统氨浸工艺浸出率较低现状,采用氧化氨浸工艺浸出回收铜镉渣中的镉、锌和铜.为了确定氧化氨浸工艺的最佳浸出条件,采用正交实验的方法研究了铜镉渣氧化氨浸的影响因素.结果表明:在氨水浓度3.7 mol/L,铵离子浓度5.0 mol/L和(NH4)2S2O8浓度30 g/L、液固比6∶1的条件下,镉、铜的浸出率达到99%,同时锌的浸出率达到96%,浸出率明显高于传统氨浸方法.

铜镉渣常温常压氧化氨浸工艺研究

以过硫酸铵为氧化剂,氨为络合剂,采用常温常压氧化氨浸工艺浸出铜镉渣中有价金属锌、镉和铜。对浸出过程工艺条件进行研究,结果表明:在氨水浓度3.4 mol/L、铵离子浓度5.0 mol/L、(NH4)2S2O8浓度30 g/L、液固比5∶1、浸出时间60 min的条件下,铜、镉的浸出率达到99%,同时锌的浸出率达到95%。

新疆滴水低品位氧化铜矿常温氧化氨浸工艺研究

以新疆滴水低品位氧化铜矿为研究对象,在(NH4)2SO4-NH3浸出体系中分别考察了磨矿细度、浸出时间、总氨浓度、氧化剂用量、NH4+∶NH3比率等因素对铜浸出率的影响。最终确定最佳工艺条件为:磨矿细度-0.074 mm粒级占86%,反应温度25℃,搅拌转速200 r/min,一段浸出液固比2∶1,过硫酸铵0.15 mol/L,氨水浓度3 mol/L,硫酸铵浓度1.5 mol/L,搅拌浸出1.5 h,静置0.5 h;二段过硫酸铵、氨水和硫酸铵添加用量减半,继续搅拌浸出1.5 h,静置0.5 h;三段浸出药剂用量与二段浸出相同,搅拌浸出2h,静置4 h完毕。该条件下,可获得铜浸出率大于86%的优良指标。

闪锌矿氧化氨浸行为研究

在NH_3-(NH_4)_2SO_4体系中,采用氧化氨浸出工艺研究了不同氧化剂(Na_2S_2O_8和BaO_2)对闪锌矿氧化氨浸行为的影响。结果表明,在110℃、常压、总氨浓度4mol/L、[NH_3]/[NH_4^+]=5/3、转速500r/min、液固比25、粒度0.063mm、浸出时间4h的条件下,以Na_2S_2O_8和BaO_2为氧化剂时,锌浸出率分别为28.4%和82%。

氧化氨浸工艺回收硫化砷渣中的铜

对在(NH4)2S2O8-NH3-H2O体系中氧化浸出硫化砷渣(砷渣)中的铜进行热力学分析;讨论了浸出温度、c(NH3)/c(NH+4)、液固比、浸出时间及总氨浓度对铜浸出率的影响,确定了从砷渣中回收铜最佳浸出工艺条件;采用XRD和SEM对浸出渣进行表征。结果表明,氧化氨浸回收铜工艺具有热力学可行性;在浸出温度35℃,c(NH3)/c(NH+4)1∶7,液固比6∶1,浸出时间3 h,总氨浓度4 mol/L的条件下,铜的浸出率为70.74%;大量S0均匀分布在浸出渣中。

NH_3-NH_4Cl-H_2O体系低品位硫化铜矿氧化浸出-脉冲电积工艺

采用单因素试验法,研究某低品位硫化铜精矿(Cu 7.42%(质量分数))在NH_3-NH_4Cl-H_2O体系中的氧化浸出行为。结果表明:在液固比4:1、[NH_3·H_2O]=1 mol/L、[NH4Cl]=3 mol/L、氧化剂过量系数1.4、原料粒度94～124μm、浸出时间2h、温度30℃的条件下,该低品位硫化铜矿浸出率98.89%;并在此基础上开展了从该低品位硫化铜精矿铜氨浸出液中直接脉冲电积铜的工艺优化试验。结果表明:在[NH_4Cl]=3 mol/L、[NH_3·H_2O]=1.5 mol/L、[Cu^(2+)]=20 g/L、明胶0.06 g/L、硫脲0.05 g/L、脉冲电流密度600 A/m2、占空比90%的条件下,可以获得平整光滑且有金属光泽的阴极铜,阴极电流效率87.97%。阴极铜XRD分析结果表明:氨-氯化铵体系中脉冲电积铜晶体主要沿(220)晶面生长,其余晶面未见明显反射峰,表现出类单晶结构。SEM分析显示:该阴极铜表面光滑致密且无瘤状物产生,铜在阴极表面的生长方式呈与阴极面垂直的一维方向生长。

多金属银矿湿法处理工艺研究

某以银为主的多金属精矿,银以固溶体形态存在于方铅矿及闪锌矿中。直接氰化时,银浸出率小于10%,金浸出率小于50%,因此应先进行预处理以提高金银浸出率。结果表明,对含金、银、铜、铅、锌的多金属精矿,采用氨浸—氰化或氨浸—酸脱铅—氰化方案可以得到良好效果。在85～100℃、0.2MPa氧压条件下进行氨性浸出后,铜、锌浸出率分别达到99%及93.8%,铅转化率94.8%,再进行常规氰化,金、银氰化浸出率分别达到98%及99%。

湿法工艺处理多金属银矿扩大试验

针对某以银为主的多金属精矿,在前期氧化氨浸—氰化工艺小型试验基础上,进行了6kg和30t/d级的扩大试验。结果表明,氨浸渣脱铅率可达到93%,脱铅渣中金氰化率可达到95%以上,当吨矿NaCN用量达到20kg时,银氰化率也可达到97%以上,扩试结果与小试结果基本一致。根据工业试验相关经济核算,3年内可回收成本。

Leaching kinetics of low-grade copper ore containing calcium-magnesium carbonate in ammonia-ammonium sulfate solution with persulfate

The leaching kinetics of copper from low-grade copper ore was investigated in ammonia-ammonium sulfate solution with sodium persulfate. The effect parameters of stirring speed, temperature, particle size, concentrations of ammonia, ammonium sulfate and sodium persulfate were determined. The results show that the leaching rate is nearly independent of agitation above 300 r/min and increases with the increase of temperature, concentrations of ammonia, ammonium sulfate and sodium persulfate. The EDS analysis and phase quantitative analysis of the residues indicate that bornite can be dissolved by persulfate oxidization. The leaching kinetics with activation energy of 22.91 kJ/mol was analyzed by using a new shrinking core model （SCM） in which both the interfacial transfer and diffusion across the product layer affect the leaching rate. A semi-empirical rate equation was obtained to describe the leaching process and the empirical reaction orders with respect to the concentrations of ammonia, ammonium sulfate and sodium persulfate are 0.5, 1.2 and 0.5, respectively.

Leaching behavior of zinc from crude zinc oxide dust in ammonia leaching

Zinc extraction from crude zinc oxide(CZO)is beneficial to the full utilization of secondary resources and environmental protection.In this paper,a systematic investigation was carried out to study the leaching behavior of CZO by using ammonia-ammonium carbonate solution.It was found that the maximum leaching rate of zinc from CZO dust was 95.7%under the conditions of[Zn]T:[NH 3]T:[CO_(3)^(2−)]=1:7.00:1.75,liquid to solid ratio 5:1,leaching temperature 30℃ and leaching time 60 min.Compared with pure zinc oxide(PZO)leaching,the CZO leaching required longer time and more leaching agents,which is caused by the Cd^(2+),Pb^(2+) and other metal cationic impurities in CZO.The metal cationic impurities dissolved in the leaching solution and combined with ammonium to form complexes,consuming leaching agents and affecting zinc leaching.

Thermodynamics of solubility of Cu_2(OH)_2CO_3 in ammonia-ammonium chloride-ethylenediamine(En)-water system

In order to decrease the evaporating rate of ammonia and increase the solubility of copper in the solution,ethylenediamine was added into the ammonia-ammonium chloride system to leach the copper-containing oxide ores.The thermodynamic model was constructed and the solubility of malachite Cu2(OH)2CO3 in the ammonia-ammonium chloride-ethylenediamine(En)-water system was calculated using the exponential computation method based on both mass balance and charge balance.It is found that the solubility of copper can be increased and the free ammonia concentration can be decreased by submitting partial ammonia with ethylenediamine.The lower free ammonia concentration in the solution is a guarantee to the lower evaporating rate of ammonia.The conditions of malachite Cu2(OH)2CO3 converting to atacamite Cu(OH)1.5Cl0.5 were also studied.A group of experiments were designed to validate the veracity of the results of the thermodynamic calculation.It is found that the thermodynamic model is reliable and it can guide the leaching process.