Electrochemical mechanism and flotation of chalcopyrite and galena in the presence of sodium silicate and sodium sulfite

The electrochemical mechanism involved in the selective separation of chalcopyrite from galena was investigated by flotation and electrochemical methods in the presence of sodium sulfite and sodium silicate, respectively, as a single depressant and their mixture as a combined depressant. Flotation tests revealed that the floatability of chalcopyrite was unaffected by depressants and its recovery remained constant (>80%) within the studied dosage range. Galena flotation was severely depressed with descending depressing order as follows: combined depressant > sodium silicate > sodium sulfite. Electrochemical analysis confirmed the high affinity of depressants on the galena surface, resulting in the formation of hydrophilic species, such as lead sulfite, lead sulfate, and lead orthosilicate. The oxidation of chalcopyrite sutrface and depressants did not exhibit any signals; conversely, the self-oxidation of chalcopyrite was depressed. The results of cyclic voltammograms well agreed with flotation results, demonstrating that chalcopyrite primarily reacted with the collector O-isopropyl-N-ethyl thionocarbamate and that galena mostly reacted with depressants.     

2,3-二羟基丙基二硫代碳酸钠对铜铅硫化矿可浮性的影响

在丁铵黑药浮选体系中,研究含有—OH和—CSS—的2,3-二羟基丙基二硫代碳酸钠（SGX）对黄铜矿和方铅矿的抑制效果,并通过动电位和吸附量的测试,探讨抑制剂SGX与矿物的相互作用机理。浮选试验研究结果表明：在整个p H范围内,抑制剂SGX对黄铜矿有活化作用,而对方铅矿有很强的抑制作用。随着抑制剂SGX用量的增加,方铅矿的回收率迅速下降,而黄铜矿的回收率有小幅度的升高。在矿浆p H为6的条件下,人工混合矿浮选得出的精矿中铜的品位和回收率分别为29.52%和82.15%。通过动电位和吸附量的测试结果可知,抑制剂SGX在方铅矿表面有较强的吸附,而在黄铜矿表面吸附很弱。     

Hydro-chemical conversion of galena in FeCl3-KCl solution

The behaviours of complexation and dissolution of PbCl₂ on the surface of galena were investigated to explore the process of hydro-chemical conversion of galena (PbS) in chloride media. By means of solution chemistry calculation, the production and dissolution of the products PbCl₂ were studied. And the passivation of the galena was studied by Tafel curve. The results show that PbCl₄²⁻ is the main form of PbCl₂ presented in the saturated potassium chloride (KCl) solution. The PbCl₂ crystal is easy to precipitate when the total concentration of chloride ion ([Cl⁻]_T) is equal to 0.92 mol/L, and it is inclined to dissolve when [Cl⁻]_T is more than 0.92 mol/L. The chloride complexing reaction rate strongly depends on the Fe³⁺ion concentration when it is less than 6×10⁻⁴mol/L, while passivation occurs on the surface of the electrode when Fe³⁺ concentration is larger than 6×10⁻⁴mol/L. The reaction rate increases obviously when KCl is added, since the activity of Cl⁻ increases; thus accelerates the dissolution of PbCl₂.     

Electrodeposition of dixanthogen on surface of pyrrhotite electrode

1　ＩＮＴＲＯＤＵＣＴＩＯＮＩｎｔｈｅｐａｓｔｄｅｃａｄｅｓ ,ｇｒｅａｔａｄｖａｎｃｅｓｔｏｗａｒｄｓｕｎ ｄｅｒｓｔａｎｄｉｎｇｔｈｅｒｅａｃｔｉｏｎｓｏｆｓｕｌｆｉｄｅｍｉｎｅｒａｌｓｕｒｆａｃｅｗｉｔｈｘａｎｔｈａｔｅｒｅａｇｅｎｔｓｈａｖｅｂｅｅｎｍａｄｅ .Ｔｈｅｋｅｙｔｏｔｈｅｓｅａｄｖａｎｃｅｓｉｓｒｅｃｏｇｎｉｚｉｎｇｔｈａｔｔｈｅｒｅａｃｔｉｏｎｓｉｎ ｖｏｌｖｅｃｈａｒｇｅｔｒａｎｓｆｅｒ .Ｍａｎｙｄｙｎａｍｉｃｅｌｅｃｔｒｏｃｈｅｍｉｃａｌｔｅｃｈｎｉｑｕｅｓｈａｖｅｂｅｅｎａ…     

含银方铅矿表面性质及捕收机理模拟计算研究

采用丁铵黑药、乙基黄药和乙硫氮3种硫化矿捕收剂对含银方铅矿进行浮选试验,基于密度泛函理论对浮选机理进行了模拟计算研究。浮选试验表明,与高碱性矿浆相比,含银方铅矿更适宜在pH为9.5的弱碱性矿浆中浮选;丁铵黑药表现出对含银方铅矿更强的选择性和捕收性。捕收机理研究结果表明,与理想方铅矿相比,含银方铅矿的带隙更窄,此外费米能级附近也新增了银原子的4d轨道,表明含银方铅矿具有更强的电化学反应活性。根据前线轨道理论,当采用丁铵黑药和乙基黄药做捕收剂时,含银方铅矿的前线轨道有效质量更低,表明含银方铅矿更易与这2种捕收剂发生吸附;随着银含量的增加,吸附过程的前线轨道有效质量呈明显下降趋势,也表明银原子会增强捕收剂与矿物表面的吸附过程。分子动力学模拟计算结果表明,丁铵黑药在含银方铅矿表面的吸附能最低,表明丁铵黑药对含银方铅矿选择性最好。     

硫化矿物的浮选电化学与浮选行为

研究黄铜矿、黄铁矿、方铅矿等矿物在有/无捕收剂两种情况下的浮选行为,考察浮选与矿浆电位的关系。结果表明:当pH值分别小于4.0时,黄铜矿无捕收剂浮选的电位区间为0~0.9 V;当pH值为4.0或11.0时,矿浆电位大于0.85 V以后,黄铁矿的浮选回收率低于20%;当pH值为11.0时,黄铜矿无捕收剂浮选的矿浆电位区间为0.35~0.85 V。当pH值为10.0、丁黄药浓度为5×10-5 mol/L时,方铅矿浮选的矿浆电位为0.45~0.55 V,而黄铜矿在0.45~0.80 V的电位区间具有良好的浮选性能;对闪锌矿而言,当pH值为9.0时,矿浆电位在-0.40~0.80 V区间都不具有良好的可浮性。在浮选体系中,黄铜矿表面氧化会产生元素S0,当矿浆电位从-0.2V增大至0.6 V,黄铜矿表面氧化产生的元素S的数量逐渐增大,黄铜矿的无捕收剂浮选性能越来越好。从南京和青海2个铅锌矿山的应用情况来看,采用电位调控浮选技术可以大幅度缩短铅矿石的浮选时间,减少浮选机数量。例如在南京某铅锌矿,由于采用电位调控浮选技术,原来2个系列每天处理900 t矿石,现在采用一个系列即可处理。     

乙硫氮在铁闪锌矿表面吸附的电化学行为及机理

采用光谱分析、循环伏安及恒电位阶跃法,研究了乙硫氮(NaD)在铁闪锌矿表面吸附的电化学行为及机理,该机理与浮选电化学的混合电位模型并不一致.在酸性条件下,当电位为0～200 mV时,乙硫氮在铁闪锌矿表面电化学吸附形成双乙硫氮(D2);当电位为410 mV时,乙硫氮与矿物发生电化学反应形成ZnD2和S°,并产生钝化,且表面疏水性强;当电位大于600 mV,电极过程由自腐蚀反应控制.在中性和碱性条件下,铁闪锌矿表面的电极过程主要由自腐蚀阳极溶解控制.随着pH值的增大,表面中间态分别为Fe(OH)D2、Fe(OH)2D和Zn(OH)D,并随电位增大进一步氧化成Zn(OH)2、Fe(OH)3和D2,且矿物表面亲水性强.在开路电位条件下,铁闪锌矿表面存在双乙硫氮和乙硫氮金属盐,但不能有效地附着在电极表面.     

Technological condition in slurry electrolysis of high-silver galena concentrate

Effects of various technological conditions such as ρ(C1^- ), ρ(Fe)T, pH value and temperature on the cell voltage, lead leaching rate and the cathodic current efficiency of the slurry electrolysis of high-silver galena concentrate were studied, and the behavior regularity of lead and silver was investigated. As a result, the suitable condition was determinedas, ρ(C1^-)230g/L, ρ(Fe)T15g/L, pH 1, temperature 70℃, electrolysis time 6h. Under such condition,adopting the cathodic current density of 150 A/m2 and the liquid-solid ratio of 15 : 1, lead powder with a purity degree of 91. 18% was got. At the same time, leaching rate of lead, leaching rate of silver and cathodic current efficiency amounted to 96.88%, 70.88% and 75.68% respectively.     

O，O-二（2，3-二羟基丙基）二硫代磷酸对黄铜矿和方铅矿的选择性抑制

以丁铵黑药为捕收剂,添加一种新型抑制剂O,O-二（2,3-二羟基丙基）二硫代磷酸（DHDTP）对黄铜矿和方铅矿进行浮选,通过动电位和吸附量的测试,探讨抑制剂DHDTP与矿物的相互作用机理。浮选试验结果表明：在整个pH范围内,抑制剂DHDTP对黄铜矿的抑制作用很弱;在pH6～10范围内,抑制剂DHDTP对方铅矿有很强的抑制作用。随着抑制剂DHDTP用量的增多,方铅矿的回收率迅速降低,而黄铜矿的回收率只有小幅度的降低。在DHDTP用量278mg／L、矿浆pH6的条件下,人工混合矿浮选得出的精矿中铜的品位和回收率较好,分别为24．08％和81％。通过动电位和吸附量的测试结果可知,DHDTP在方铅矿上的吸附能力明显高于黄铜矿的。     

Tube electrode high-speed electrochemical discharge drilling using low-conductivity salt solution

Film cooling holes are widely used in the aerospace industry, and their fabrication requires high machining speed and accuracy, as well as good surface quality. Tube electrode high-speed electrochemical discharge drilling (TSECDD) is a promising hybrid machining method for the fabrication of film cooling holes in difficult-to-machine superalloys. An electrochemical reaction can occur if a low-conductivity salt solution is used in the drilling. Materials can also be removed at a high speed using electrical discharge machining (EDM). Thus, TSECDD and electrochemical machining (ECM) can be combined into a unique machining process using a low-conductivity salt solution. This machining process achieves both a high machining speed and good surface finish. In this study, the material removal mechanism of TSECDD was studied using a low-conductivity salt solution, and comparisons with high-speed electrical discharge drilling were made. The performance of the process was investigated using salt solutions of various conductivities. The results show that there are different material removal mechanisms in the frontal gap and the lateral gap and that, in the latter, there is a transition from EDM to ECM. Experiments conducted using TSECDD confirm that the use of this process with a low-conductivity salt solution can improve the machining surface and machining efficiency achieved. The results also show that the use of a low-conductivity solution improves the material removal rate, the hole diameter, and the taper angle.     

Galena-pyrolusite co-extraction in sodium chloride solution and its electrochemical analysis

The co-extraction behavior of galena-pyrolusite in a sodium chloride solution and the electrochemical mechanism of this process were investigated, and some factors affecting the leaching rate of Pb and Mn were optimized. The results show that all the factors such as the concentration of NaCl, HCl and pyrolusite ore, reaction time, temperature, adding times of HCl, affect the leaching rate of Pb. The main affecting factors are the concentration of NaCl, reaction time and temperature. The Tafel polarization curves and EIS plots of the galena and pyrolusite in the NaCl solution demonstrate that during the oxidation process of galena mineral electrode, film forms on the galena surface, which prevents galena from deeper oxidation. However, the film resistance can be greatly reduced in the presence of sodium chloride, thus promoting the reaction rate of galena.     

Study of the electrochemical properties of a transition metallic ions modified electrode in acidic VOSO4 solution

Graphite material was used as the electrode for an all-vanadium redox flow battery, and the electrode was modified by transition metallic ions to enhance its electrochemical behavior. An porous graphite composite electrode has high specific surface area and high current density. The electrode modified by transition metallic ions has improved catalysis behavior that can catalyze the V（Ⅱ）-V（Ⅴ） redox reaction showed by cyclic voltammograms. This article studied the impedance of the modified electrode by electrochemical impedance spectroscopy （EIS）, and approved that the electrode modified by Co^2＋ and Mn^2＋ has a lower charge transfer resistance than the non-modified electrode. The effect of average particle size distribution is at lower frequencies that the slope of Warburg impedance is reduced by large particle size distribution. The voltage efficiency of the Co^2＋ modified electrode test cell is 81.5%, which is higher than that of the non-modified electrode.     

Influence of mechanical excitation on adsorption of sodium diethylamino dithio-formate on galena and sphalerite

1　ＩＮＴＲＯＤＵＣＴＩＯＮＮｕｍｅｒｏｕｓｉｎｖｅｓｔｉｇａｔｉｏｎｓｈａｖｅｓｈｏｗｎｔｈａｔｔｈｅｍｅｃｈａｎｉｃａｌａｃｔｉｏｎｃａｎｅｆｆｅｃｔｉｖｅｌｙｃｈａｎｇｅｔｈｅｓｔａｔｅｏｆａｍａｔｅｒｉａｌ,ｃａｔａｌｙｚｅｓｏｍｅｃｈｅｍｉｃａｌｒｅａｃｔｉｏｎｓ ,ｂｒｉｎｇａｂｏｕｔｓｏｍｅｃｈｅｍｉｃａｌｃｏｎｖｅｒｓｉｏｎｓａｎｄｃｏｎｓｉｄｅｒａｂｌｙａｃ ｃｅｌｅｒａｔｅｍｕｌｔｉｐｈａｓｅｐｒｏｃｅｓｓｅｓ .Ｈｏｗｅｖｅｒ,ｔｈｉｓｋｉｎｄｏｆｒｅｓｅａｒｃｈｗａｓｍｏｓｔｌｙ…     

Preparation of lead sulfate powder directly from galena concentrates

A new approach to prepare PbSO4 powder is studied. Using the methods of the leaching of galena concentrates in the ferric chloride media, selective purification and chemical sedimentation, PbS concentrate can be converted into PbSO4. The conversion recovery is 97.39%, the purity of PbSO4 powder is above 99% and its average crystallite size is about 42 nm. In this process, emission of lead vapour and SO2 cannot occur. The experimental results demonstrate the feasibility of realizing a green route to prepare the lead sulfate powder.     

氧分子在黄铁矿和方铅矿表面的吸附

采用密度泛函理论对氧分子在黄铁矿和方铅矿表面的吸附进行研究。计算结果表明:黄铁矿和方铅矿表面经历了较小的弛豫;氧分子在黄铁矿和方铅矿表面都呈解离吸附状态,且在黄铁矿表面的吸附能远低于在方铅矿表面的吸附能;在黄铁矿表面上,氧原子分别与铁原子和硫原子键合,电子由铁原子和硫原子转移到氧原子上,主要由硫的3p态、氧的2p态和铁的3d态参与反应,铁与氧之间形成d→p反馈键,而在方铅矿表面上,氧原子只与硫原子键合,主要由硫的3p态、氧的2p态和铅的6p态参与反应,未形成反馈键;氧吸附后黄铁矿表面产生键合的铁原子和氧原子都产生自旋现象,而方铅矿表面原子及吸附的氧原子仍然是低自旋态的。     

Nocardia在黄铁矿和方铅矿表面的选择性吸附

研究了Nocardia在不同影响因素条件下在黄铁矿和方铅矿表面的选择性吸附.结果表明:Nocardia在黄铁矿和方铅矿表面可发生明显的选择性吸附,在黄铁矿表面的最大吸附率为96.99%;而在方铅矿表面的吸附率为20%左右;两种矿物表面的吸附在较短的时间内即可达到平衡;pH值是影响Nocardia在两种矿物表面发生选择性吸附的关键因素,当pH为3～10时,选择性吸附现象明显;而当矿浆浓度超过6 g/L和菌液浓度为0.5～4 g/L时,有利于选择性吸附;温度对吸附效果影响较小.扫描电镜检测结果表明,Nocardia细胞外膜表面的菌丝是重要的吸附位;矿物解理面状态、Nocardia表面基团的桥连作用和静电力是导致选择性吸附的关键.     

CuW合金电极窄缝线切割加工工艺规律试验研究

结合数控精密低速走丝线切割NA2400机床的特点,通过控制单因素进行了试验,分析了伺服基准电压(VG)、峰值电流(IP)、电极丝张紧力(WT)及走丝速度(WS)分别对切缝宽度、平均加工速度及表面质量的影响规律,为实际切割相应尺度结构的CuW合金电极提供理论指导。     

Kinetics of electrochemical corrosion of chalcopyrite in presence of bacteria

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｉｍｐｏｒｔａｎｔｂａｃｔｅｒｉａｉｎｂｉｏｈｙｄｒｏｍｅｔａｌｌｕｒｇｙａｒｅｍａｉｎｌｙａｅｒｏｂｉｃｃｈｅｍｏｌｉｔｈｏｔｒｏｐｈｉｃｓｐｅｃｉｅｓ ,ｏｆｗｈｉｃｈｔｈｅｍｏｒｅｉｍｐｏｒｔａｎｔａｒｅＴｈｉｏｂａｃｉｌｌｕｓｆｅｒｒｏｏｘｉ ｄａｎｓａｎｄＴｈｉｏｂａｃｉｌｌｕｓｔｈｉｏｏｘｉｄａｎｓ .ＴｈｅｐｒｏｐｅｒｔｉｅｓｏｆｔｈｅｔｗｏｓｐｅｃｉｅｓａｒｅｓｈｏｗｎｉｎＴａｂｌｅ 1.Ｔｈｅｙｃａｔａｌｙｚｅｔｈｅｏｘｉｄａｔｉｏｎｏｆｓｏｍｅｏｒａ…     

注射模电极电火花加工工艺图自动生成技术研究

分析了手工绘制电火花加工工艺图存在的缺点,对电火花加工工艺图的标准化及自动化进行了研究,利用UG二次开发技术,将电极设计过程中涉及到的电极命名规则、电极信息的建立与保存等相互关联,实现了电极命名、电极参数设置及电火花加工工艺图绘制的自动化,有效避免了手工绘图的出错率,在大幅提高电极设计效率的同时,降低了人为错误引起的成本损失。