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71.
I.S. Yahia M. FadelG.B. Sakr F. Yakuphanoglu S.S. ShenoudaW.A. Farooq 《Journal of Alloys and Compounds》2011,509(12):4414-4419
The polycrystalline ZnGa2Se4 thin film was prepared by thermal evaporation technique on n-Si wafer followed by annealing at 700 K. Then, the Al/p- ZnGa2Se4/n-Si/Al heterojunction diode was fabricated. XRD pattern shows that the annealed ZnGa2Se4 film has a polycrystalline structure. AFM images indicate that the ZnGa2Se4 film is formed of nanoparticles. The dark current-voltage characteristics of the heterojunction diode at various temperatures have been investigated to determine the electrical parameters and conduction mechanism. The Al/p-ZnGa2Se4/n-Si/Al diode shows a rectification ratio of 2.644 × 102 at ±2 V at room temperature. It was found that at forward bias voltages ≤0.5 V, the conduction mechanism of the diode is controlled by the thermionic emission mechanism, while at bias voltages higher than 0.5 V, it is controlled by the space charge limited current mechanism. The series resistance Rs, the ideality factor n and the barrier height ?b values of the diode are determined by performing different plots from the forward current-voltage characteristics. The reverse current mechanism of the diode is controlled by the carrier generation-recombination process in the depletion region. The obtained results show that the Al/p-ZnGa2Se4/n-Si/Al heterojunction is a good candidate for the electronic device applications. 相似文献
72.
《中国有色金属学会会刊》2022,32(5):1650-1663
The pressure leaching mechanism of chalcopyrite was studied by both leaching tests and in-situ electrochemical measurements. The effects of leaching temperature, oxygen partial pressure, and calcium lignosulphonate, on copper extraction and iron extraction of chalcopyrite pressure leaching were investigated. The leaching rate is accelerated by increasing the leaching temperature from 120 to 150 °C and increasing oxygen partial pressure to 0.7 MPa. The release of iron is faster than that of copper due to the formation of iron-depleted sulfides. Under the optimal leaching conditions without calcium lignosulphonate, the copper and iron extraction rates are 79% and 81%, respectively. The leaching process is mixedly controlled by surface reaction and product layer diffusion with an activation energy of 36.61 kJ/mol. Calcium lignosulphonate can effectively remove the sulfur passive layer, and the activation energy is 45.59 kJ/mol, suggesting that the leaching process with calcium lignosulphonate is controlled by surface chemical reactions. Elemental sulfur is the main leaching product, which is mixed with iron-depleted sulfides and leads to the passivation of chalcopyrite. Electrochemical studies suggest that increasing the oxygen partial pressure leads to increasing the cathodic reaction rate and weakening the passivation of chalcopyrite. 相似文献
73.
The effect of extracelluar polymeric substances(EPS) on the bioleaching chalcopyrite concentrates in the presence of ironand sulphur-oxidizing bacteria (A. ferrooxidans) was studied. The bacterial number, pH, redox potential, and the concentrations of Fe^2+ and Cu^2+ ions were investigated. The leached residues were analyzed by the X-ray diffraction and FT-IR. The results indicate that the EPS makes the bacteria adhere to the chalcopyrite surface easily and it is helpful for bacteria in disadvantageous environment At the same time, EPS film layer with Fe^3+ deposits on the surface of chalcopyrite and becomes a barrier of oxygen transfer to chalcopyrite to passivate chalcopyrite, and creates the high redox potential space through concentrating Fe^3+ ions to accelerate bioleaching pyrite in chalcopyrite concentrates. The results suggest that EPS formation promotes bioleaching pyrite and inhibits bioleaching chalcopyrite, especially under high potential condition. 相似文献
74.
采用微生物浸矿技术,以西部矿业黄铜矿为对象,进行了从黄铜矿中提取铜的实验研究。菌种为氧化亚铁杆菌(T.f)。先进行菌种富集制备T.f菌浸出液,用细菌摇瓶浸出法做实验,了解影响浸出率的各种技术因素。研究结果得出,西部矿业黄铜矿在一般温度(25℃)下,T.f菌浸液的起始pH值为2.5,细菌浸出效果良好,浸出率平均在40%~65%之间,最高达到67%左右。为明确了解T.f菌浸出的效果,进行了无菌化学浸出的平行实验,两组系列实验结果得出,在整个浸出过程中,有菌浸出与无菌浸出相比,前期有菌浸出占有明显优势,但在后期浸出,效果与无菌浸出相当。这是由于有菌浸出后期pH值较前期低,不利于细菌的生长繁殖,此时,浸出时应使用pH值控制器,使其pH保持在合适的范围内,就能继续高的浸出速率。 相似文献
75.
76.
在研究和分析10#矿体含铜硫铁矿石性质的基础上,进行了优先浮选和混合浮选试验,为企业开发利用这部分低品位硫铁矿石提供了技术依据。 相似文献
77.
硫化铜、铅矿物浮选分离研究现状及发展趋势 总被引:15,自引:4,他引:15
在矿产资源开发强度日益增大的大环境里,人们对多金属复杂矿石的利用和研究的兴趣也越来越大。本文通过对硫化铜、铅矿物的浮选分离进行总结,认为目前研究最多的是优先浮选流程、混合浮选流程和等可浮流程,指出了常用的捕收剂和抑制剂等药剂制度。介绍了铜铅混合精矿分离常用的方法,包括重铬酸盐法、亚硫酸(盐)法和其他多种方法。阐述了多种方铅矿抑制剂的抑制机理。对硫化铜、铅矿物的浮选电化学研究成果进行了全面总结,分析了黄铜矿、方铅矿单矿物的电化学特性,综述了两种单矿物的人工混合矿的电化学分离条件以及电化学控制浮选和原生电位浮选的理论内涵,并指出了下一步研究的方向。 相似文献
78.
采用电化学测试和X射线光电子能谱(XPS)测试分析黄铜矿与斑铜矿在酸性细菌培养基中的电化学溶解过程。斑铜矿直接氧化反应比还原反应更容易发生,但黄铜矿既难被氧化,又难被还原。斑铜矿具有更高的氧化速率,从而比黄铜矿更容易被溶解。铜蓝(CuS)是黄铜矿与斑铜矿溶解过程的中间产物。因此,斑铜矿的溶解途径主要为直接氧化过程,中间产物铜蓝(CuS)可能限制其进一步溶解。黄铜矿的溶解途径包含了还原-氧化过程,其中,黄铜矿首先被还原为与斑铜矿类似的中间产物,再进一步被氧化,并产生铜蓝(CuS),而黄铜矿的最初还原过程是其溶解过程的主要限制步骤。 相似文献
79.
H. Naderi M. Abdollahy N. Mostoufi M.J. Koleini S.A. Shojaosadati Z. Manafi 《北京科技大学学报(英文版)》2011,18(6):638-645
The kinetics of the chemical leaching of copper from low grade ore in ferric sulfate media was investigated using the constrained least square optimization technique.The experiments were carried out for different particle sizes in both the reactor and column at constant oxidation-reduction potential (Eh),pH values,and temperature.The main copper mineral was chalcopyrite.About 40% of Cu recovery is obtained after 7 d of reactor leaching at 85℃ using -0.5 mm size fraction,while the same recovery is obtained at 75℃ after 24 d.Also,about 23% of Cu recovery is obtained after 60 d of column leaching for +4-8 mm size fraction whereas the Cu recovery is as low as about 15% for +8-12.7 and +12.7-25 mm size fractions.A 4-stage model for chalcopyrite dissolution was used to explain the observed dissolution behaviors.The results show that thick over-layers of sulphur components cause the parabolic behavior of chalcopyrite dissolution and the precipitation of Fe3+ plays the main role in chalcopyrite passivation.In the case of coarse particles,transformation from one stage to another takes a longer time,thus only two stages including the initial reaction on fresh surfaces and S0 deposition are observed. 相似文献
80.
含铜难处理金矿直接氰化浸出率一般较低, 氰化物耗量大, 需经预氧化浸出除去含铜杂质后再氰化浸出。以硫化铜矿物为研究对象, 在添加氯盐的酸性体系中, 开展了黄铜矿加温、加压预氧化浸出过程研究。探讨了预氧化温度、氧气压力、起始硫酸用量、起始氯化钠浓度等对黄铜矿中铜、铁浸出的影响行为。通过理论分析、浸出液化学分析以及黄铜矿预氧化浸出渣的X射线衍射测试研究了黄铜矿酸性体系预氧化浸出的反应历程和预氧化浸出渣的成分。结果表明, 氧化反应初期, 氧气分压、起始硫酸用量、氯化钠用量越大, 铜越容易被浸出, 而氧化后期氧气压力对铜浸出影响较小。预氧化浸出过程中有Cu9Fe9S16、Cu39S28及黄钠铁矾和草黄铁矾生成, 而黄钠铁矾和草黄铁矾为渣中的最终产物。 相似文献