Dynamics in simultaneous electro-generative leaching for sphalerite-MnO2

The principle for the electro-generative leaching was applied to simultaneous leaching of sphalerite-MnO2. A galvanic system for the bio-electro-generative leaching was set up. The effects of grain size and temperature on rate of zinc extraction fi＇om sphalerite under the conditions of presence and absence ofAcidithiobacillusferrooxidans （A.ferrooxidans） were studied, respectively. The results show that with bacteria, the maximum extraction of zinc fi＇om the ores with grain size of 16.6 μm can reach 32.01% after leaching for 12 h, while to obtain the same extraction ratio in the traditional bio-leaching route （i.e. not electro-generative one）10 d is needed to ore granules with same size. The unreacted shrinking core model was used for describing the reaction-relative and diffusion-relative phenomena presented in the process of the electro-generative leaching with and without bacteria, which is considered to be diffusion controlled. The activation energies of the anodic reaction for leaching system in the presence and absence of bacteria are 11.97 and 14.39 kj/mol, respectively, indicating that leaching rate can be decreased by A. ferrooxidans. SEM was used to study the effect ofA. ferrooxidans on the ores in the simultaneous electro-generative leaching, which indicates that the produced sulfur on the surface of the sulfides can be oxidized by A. ferrooxidans after bio-electro-generative leaching for 24 h, and the transferred charge due to the bacterial oxidation is up to 17.86%, which is an important part of the output electric quantity.     

原电池效应对混合硫化矿细菌浸出的影响

研究了黄铜矿与黄铁矿混合矿细菌浸出过程的原电池效应，提出了原电池效应模型。研究结果表明：当黄铜矿细菌浸出过程中加入黄铁矿及C时，浸出率大大提高，黄铜矿浸出30d，Cu浸出率可达40％；单一黄铁矿细菌浸出时，黄铁矿会被大量氧化分解，而当与黄铜矿混合浸出时，黄铜矿氧化加快，黄铁矿氧化速率降低；加入C及黄铁矿与黄铜矿混合时，由于接触电位的影响，黄铜矿氧化反应电流增大、反应起始电位负移，反应加尉，而黄铁矿的氧化反应受到抑制；混合矿浸出过程中，黄铜矿表面Cu含量较单一矿浸出时低得多，说明混合效应对浸出具有强化作用；黄铜矿中Cu浸出愈多，表面生成的元素硫愈多，黄铁矿细菌浸出时，表面不会有元素硫产生。     

镍黄铁矿电化学生物氧化过程的分解机理(英文)

应用表面粘附和没有粘附Acidithiobacillus ferrooxidans的镍黄铁矿粉末微电极进行电化学测试,以说明镍黄铁矿氧化分解的机理。循环伏安CV结果显示,在-0.2V的低电位区域,在镍、铁离子析出时镍黄铁矿转变为中间相Fe4.5-yNi4.5-xS8-z;当电位在-0.2V到0.2V区间时,有不稳定的紫硫镍矿Fe3Ni3S4和FeNi2S4形成并在表面伴有元素硫的产生;当电位增加到0.2V以上时,不稳定相将全部分解;在高电位0.7V时,析出的亚铁离子被氧化为高铁离子。嗜酸氧化亚铁硫杆菌Acidithiobacillus ferrooxidans的存在使峰电位增高,反应起始电位负移,并对表面形成的元素硫有氧化去除作用。这一过程可通过-0.75到-0.5V电位区间发生的的还原反应证实。生物浸出和电化学实验结果均表明当pH2时溶液酸度的增加对氧化过程有轻度的阻碍作用。     

Study on bioleaching of refractory gold ore (Ⅰ)──Mechanism on bioleaching of pyrite by Thiobacillus ferrooxidans

1　ＩＮＴＲＯＤＵＣＴＩＯＮＳｔｕｄｉｅｓｏｎｔｈｅｇｒｏｗｔｈ[1～ 3 ] ａｎｄａｐｐｌｉｃａｔｉｏｎｓ[4 ] ｏｆＴｈｉｏｂａｃｉｌｌｕｓｆｅｒｒｏｏｘｉｄａｎｓｈａｖｅｂｅｅｎｃａｒｒｉｅｄｏｕｔｂｙｍａｎｙｒｅｓｅａｒｃｈｅｒｓ ,ｓｉｎｃｅｉｔｉｓｏｎｅｏｆｔｈｅｍｏｓｔｉｍｐｏｒ ｔａｎｔｍｉｃｒｏ ｏｒｇａｎｉｓｍｓｆｏｒｔｈｅｒｅｃｏｖｅｒｙｏｆｓｏｍｅｍｅｔａｌｓｉｎｃｌｕｄｉｎｇｃｏｐｐｅｒａｎｄｕｒａｎｉｕｍｆｒｏｍｌｏｗ ｇｒａｄｅｏｒｅｓｉｎｉｎｄｕｓｔｒｉａｌｈｅａｐ ,ｄｕｍｐ ,…     

Liquid-nitrogen cryopreservation of three kinds of autotrophicbioleaching bacteria

Three kinds of autotrophic bioleaching bacteria strains, including mesophilic and acidophilic ferrous ion-oxidizing bacteria Acidithiobacillus ferrooxidans （A. ferrooxidans）, mesophilic and acidophilic sulfur-oxidizing bacteria Acidithiobacillus thiooxidans （A. thiooxidans）, and moderately thermophilic sulfur-oxidizing bacteria Acidianus brierleyi, were cryopreserved in liquid nitrogen and their ferrous ion- or sulfur-oxidizing activities were investigated and compared with the original ones. The results revealed that ferrous ion/sulfur oxidation activities of the strains were almost equal before and after cryopreservation. Glycerin was used as cryoprotective agent. In conclusion, liquid-nitrogen cryopreservation is a simple and effective method for autotrophic bioleaching microorganisms.     

Submicro-battery effect and selective bio-oxidation model of gold-bearing arsenopyrite by Thiobacillus ferrooxidans

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｒｅａｒｅｍａｎｙｋｉｎｄｓｏｆｓｕｌｐｈｉｄｅｍｉｎｅｒａｌｓ,ｓｕｃｈａｓａｒｓｅｎｏｐｙｒｉｔｅ ,ｐｙｒｉｔｅ,ｃｈａｌｃｏｐｙｒｉｔｅ ,ｓｐｈａｌｅｒｉｔｅ ,ｇａｌｅｎａ,ｐｙｒｒｈｏｔｉｔｅ,ｓｔｉｂｎｉｔｅ ,ｔｅｔ     

Bioleaching of refractory gold ore （ Ⅱ ）——Mechanism on bioleaching of arsenopyrite by Thiobacillus ferrooxidans

1　ＩＮＴＲＯＤＵＣＴＩＯＮＢｉｏｌｅａｃｈｉｎｇｐｒｏｃｅｓｓｅｓｈａｖｅｂｅｅｎｕｓｅｄｅｘｔｅｎｓｉｖｅｌｙｔｏｒｅｃｏｖｅｒｂａｓｅｍｅｔａｌｓ (ｍａｉｎｌｙｃｏｐｐｅｒ)ａｎｄｕｒａｎｉｕｍｆｒｏｍｌｏｗ ｇｒａｄｅｏｒｅｓａｎｄｍｏｒｅｒｅｃｅｎ     

两栖车辆7A52-38CrSi扰动电偶腐蚀研究

设计了7A52-38CrSi人造海水扰动电偶腐蚀试验,研究了水流速度对电偶电流、腐蚀电压的影响,结果表明:当腐蚀介质流速一定时,7A52-38CrSi电偶腐蚀电位差随时间的延长呈减小趋势,腐蚀电流也逐渐减小.2.5m/s的相对流速是7A52-38CrSi电偶对腐蚀速率变化的关键点.SEM和能谱分析方法分析表明,在腐蚀介质扰动条件下,7A52铝合金表面钝化变弱、极化现象受到抑制是电腐蚀加速的主要原因.     

Bioleaching of anilite by Acidithiobacillus ferrooxidans

In order to characterize the efficiency of copper bioleaching from anilite using pure cultures of Acidithiobacillus ferrooxidans in the absence and presence of ferrous sulphate,the experiments were carried out in shake flasks with or without 4 g/L ferrous sulphate(FeSO_4·7H_2O)at pH 2.0,150 r/min and 35℃.The tests show that Acidithiobacillus ferrooxidans is unable to attack anilite in iron-free 9K medium.Anilite is rapidly oxidized by bacterial leaching when ferrous sulphate is added.Chemical oxidation o...     

基于DSP的全数字化IGBT逆变脉冲 MIG/MAG焊机研制(一)--硬件电路设计

设计了以TMS320F240为核心的控制系统，为了控制焊机的输出功率和焊机的输出外特性，设计采用了脉宽调制型控制方式。结合TMS320F240输出的PWM波形，设计了专门的分频电路。利用霍尔传感嚣设计了电流、电压反馈系统，形成了闭环控制系统；针对焊接过程中可能出现的过电流、过热、过／欠电压等故障．设计了相应的保护电路和报警电路。另外，研制了数字化送丝系统，该系统送丝稳定。     

大面积PCD复合片电火花加工高效节能脉冲电源的研究

本文通过对大面积PCD复合片材料物理特性的分析及电火花放电加工PCD表面放电机理的研究，分析了电火花加工大面积PCD复合片时影响加工速度及表面质量的重要因素。提出了用于加工大面积PCD复合片的理想电源模型，其特点为：大能量、高峰值电压、高峰值电流、窄脉冲、等脉冲能量输出。根据理想电源模型开发出一种高效、节能、环保型大面积PCD复合片电火花专用脉冲电源。与普通电火花脉冲电源比较，该电源加工效率高、加工表面质量好，电能利用率高，是大面积PCD复合片电火花加工的有效工具。     

智能化油井套管脉冲电流阴极保护电源控制系统

目的 设计一种智能化油井套管脉冲电流阴极保护电源控制系统,该控制系统能够自动检测外部反馈信号(包括输出电流、输出电压、套管电位),并根据外部反馈信号自适应调节电源的输出参数(包括频率、幅值、占空比),实现电源的智能化运行,确保油井套管脉冲电流阴极保护效果处于最佳状态。方法 本次控制系统设计采用三层闭环控制策略实现电源的自适应调节,其中输出电流为内环,输出电压为中环,套管电位为外环;采用先进的处理算法对输出电流、输出电压、套管电位进行处理运算,判断出脉冲电流阴极保护的保护效果,并输出相应的PWM控制信号对电源的输出参数进行实时调节。结果 在5.0×0.5×0.5m的PVC绝缘水槽中模拟油井套管脉冲电流阴极保护系统,结果表明,该控制系统能够控制电源输出频率、幅值、占空比均可独立调节的脉冲电流,并且可以使40角钢的保护电位达到-0.85V。结论 该控制系统可以实现油井套管脉冲电流阴极保护电源的智能化运行,不需要过多的人工干预,具有投入成本低、可靠性高、功能完善、操作方便等优点。     

Bioleaching of marmatite in high concentration of iron

Bioleaching of marmatite with a culture of Thiobacillus ferrooxidans and Thiobacillus thiooxidans in high concentration of iron was studied,the results show that the zine leaching rate of the mixed culture is faster than that of the sole Thiobacillus ferrooxidans,the increasing iron concentration in leaching solution enhances the zine leaching rate.The SEM analysis indicates that the chemical leaching residues is covered with porous solid layer of elemental sulfur,while elemental sulfur is not found in the bacterial leaching residues.The primary role of bacteria in bioleaching of sphalerite is to oxidize the chemical leaching products of ferrous ion and elemental sulfur,thus the indirect mechanism prevails in the bioleaching of marmatite.     

铜铝管电阻焊的电压补偿控制系统

为使铜铝管焊接质量稳定,即焊接电流稳定,分析了铜铝管焊接过程,设计了可进行电压补偿的PLC控制系统.在每次焊接前,通过测量电源电压,经控制系统分析和计算,可以得到与电源电压对应的晶闸管导通角,并将其传给触发板,从而保证焊接电流不受电源电压波动影响.导通角的计算采用了试验与数学插值相结合的方法,对特定的试验数据应用三次样条插值法得到了导通角与电源电压的关系式.用铜铝管8 mm×1 mm进行焊接试验并对电流数据进行T检验.结果表明,电源电压在380 V±15%波动范围内,焊接电流较稳定,可保证铜铝管焊接质量.     

高压逆变电子束焊接电源研制及其焊接适用性研究

为了进一步提高电子束焊机工作的可靠性和稳定性,提高电子束加工质量,采用AC-DC-AC-DCAC-DC的拓扑电路和双闭环控制策略设计制造了高压加速电源、偏压电源与灯丝加热电源。将所研制高压逆变电源与150 kV/30 kW电子枪、真空系统等组成了一套电子束焊接设备,分别测试了该电子束焊接设备输出的高压、最大束流、焊接工艺参数一致性、最大焊接深度。试验结果表明,所研制的逆变电源高压输出达到150 kV,高压输出线性度较好;工艺参数一致性较好;最大束流达到200 mA;钛合金焊接深度达到100 mm。这表明所研制的高压逆变电子束焊接电源的焊接适用性良好。     

CO_2气体保护焊逆变电源闭环控制系统

建立了CO2气体保护焊焊接负载数学模型及相关电源—负载系统仿真模型;采用燃弧末期恒压控制、其余阶段表面张力过渡(surface tension transition,STT)电流波形控制的焊接逆变电源闭环控制结构,设计了焊接电流和电弧电压的模糊神经元PI控制器,构建了CO2焊接逆变电源控制系统仿真平台.结果表明,所设计的闭环控制结构和控制算法能使焊接电流更接近理想的STT电流波形,可改善焊缝成形质量、实现无飞溅过渡;燃弧末期电弧电压恒定,可使电弧有更好的自调节特性.     

XPS characteristics of sulfur of bio-oxidized arsenic-bearing gold concentrate and changes of surface nature of bio-oxidation residue

During bio-oxidation of sulfides, the chemical state change of sulfur is a complex and key factor. It is not only an indicator of the extent and intensity of the bio-oxidation, but also controls the property of bio-leaching medium and the period of oxidation. The chemical state of sulfur in sulfides oxidized by leaching bacteria was studied with XPS. Sulfide minerals in the arsenic-bearing gold concentrate consist of pyrite, arsenopyrite, chalcopyrite, galena, sphalerite and so on. In order to probe the pattern of the chemical state change of sulfur in the bio-oxidation residue of arsenic-bearing gold concentrate, the structure of the grains, and the surface nature of the residue, XPS test was carried out through different sputtering duration. The study of XPS clearly shows that: sulfides is progressively oxidized from the surface of minerals to the core by leaching bacteria; the chemical valence of sulfur changes from S^2- or [S2]^2- to [SO4]^2- ; sulfur in the core is in a reduction state, S^2- or [S2]^2- , but exists in an oxidation state S^6 on the surface; due to the chemical state change of sulfur, mineral phase of the bio-oxidation residue is also changed(sulfides inside, while sulfates outside); the layered structure is found in the grains of the bio-oxidation residue.     

Mechanism of electro-generating leaching of chalcopyrite-MnO_2 in presence of Acidithiobacillus thiooxidans

A dual cell system with chalcopyrite anode and MnO_2 cathode was used to study the relations between time and such data as the electric quantity and the dissolution rates of the two minerals in the electro-generating leaching(EGL)and the bio-electro-generating leaching(BEGL),respectively.The results showed that the dissolution rates for Cu~(2+)and Fe~(2+)in BEGL were almost 2 times faster than those in EGL,and nearly 3 times for Mn~(2+);the electric output increased nearly by 3 times.The oxidation residu...     

Mechanism of electro-generating leaching of chalcopyrite-MnO2 in presence of Acidithiobacillus thiooxidans

A dual cell system with chalcopyrite anode and MnO2 cathode was used to study the relations between time and such data as the electric quantity and the dissolution rates of the two minerals in the electro-generating leaching（EGL） and the bio-electro-generating leaching（BEGL）, respectively. The results showed that the dissolution rates for Cu^2＋ and Fe^2＋ in BEGL were almost 2 times faster than those in EGL, and nearly 3 times for Mn^2＋; the electric output increased nearly by 3 times. The oxidation residue of chalcopyrite was represented by TEM and XRD, whose pattern was similar to that of the raw ore in EGL. The mechanism for leaching of CuFeS2-MnO2 in the presence of Acidithiobacillus thiooxidans was proposed as a successive reaction of two independent sub-processes for the anode. The first stage, common to both processes, is dissolution of chalcopyrite to produce Cu^2＋, Fe^2＋ and sulfur. The second stage is subsequent oxidization of sulfur only in BEGL, which is the controlling step of the process. However, the dissolution of MnO2 lasts until the reaction of chalcopyrite stops or the ores exhaust in two types of leaching.     

单片机控制MAG焊逆变电源设计

开发了基于单片机控制的MAG焊逆变电源,并介绍其控制原理及软硬件组成。采用IGBT全桥主电路拓扑结构,设计了MAG焊逆变电源的主电路。选用PIC16F877单片机为：控制核心,设计了MAG焊逆变电源的控制电路,包括逆变电源系统的反馈电压、电流的采集,控制量的输出以及数字量的输入、输出。此外,还设计了数字化脉宽调制送丝系统。