黄铁矿包裹型难浸金精矿的细菌预氧化工艺研究

对黄铁矿包裹型难浸金精矿采用驯化诱变菌株，在选定的氧化工艺条件下，可有效地分解载金矿物黄铁矿。黄铁矿、毒砂的氧化率分别达到了71．0％和92．45％，使该金精矿的氰化浸出率从未氧化前的41．34％提高到90％以上，且氧化时间短。该研究结果为同类型的难浸金精矿的开发利用提供了具有实际应用价值的预处理工艺。     

曼陀罗内生真菌代谢产物抗皮肤致病真菌活性成分研究

[目的]研究曼陀罗植物内生真菌Ym311977菌株代谢产物的抑菌活性及其有效成份.[方法]对Ym311977菌株进行扩大发酵培养,从发酵产物中分离单体化合物,并研究单体化合物对2株皮肤致病真菌的体外抑制活性.[结果]分离到的4种单体化合物中的1种对2株皮肤致病真菌(石膏样小孢子菌、石膏样毛癣菌)的最低抑菌浓度分别为50、200μg/ml;该化合物经'HNMR及13CNMR分析,确定其结构为5-丁基吡啶甲酸,即镰刀菌酸.[结论]该研究首次报道了曼陀罗内生真菌代谢产物镰刀菌酸对2株皮肤致病真菌具有押制活性.     

预氧化对岩矿型钛铁矿还原行为的作用机理研究

以攀枝花钛铁矿为试验对象,详细研究了预氧化对岩矿型钛铁矿还原行为的作用机理。结果表明,未处理的岩矿型钛铁矿的还原速率较慢,而预氧化能够有效提高还原速率。这是因为在预氧化矿还原前期会发生Fe~(3+)→Fe~(2+)(FeTiO_3)的快速转变反应。该反应会生成大量孔洞,破坏了钛铁矿的致密结构,有利于后续还原反应的进行。预氧化焙烧温度越高,焙烧时间越长,钛铁矿的还原速率越快。此外,预氧化还会使后续还原产生的金属Fe晶粒变小,分布变弥散。     

难浸金矿石的细菌预氧化电化学研究进展

从载金矿物砷黄铁矿、黄铁矿细菌氧化电化学,砷黄铁矿-黄铁矿原电池效应等方面论述了难浸金矿石细菌预氧化的电化学研究进展,指出浸出过程电化学研究和新型研究方法的应用是未来难浸金矿石细菌预氧化研究的主要方向。     

极端嗜热硫杆菌浸出黄铁矿

为了探讨极端嗜热菌在高铁、高酸和高温条件下生物脱硫的可行性,采用从腾冲热海酸性温泉分离出的一株新型极端嗜热硫杆菌开展了四组不同初始pH值条件下的黄铁矿生物柱浸实验.该菌株能耐受pH值为0.58、全铁质量浓度为38.9 g·L-1的高酸高铁环境,同时维持580~640 mV的较低电位.初始pH值为2时,浸出28 d后黄铁矿浸出率达到最高为17.8%.生物浸出时,菌株生长依次表现出较明显的迟缓期、对数期和稳定期,且降低初始pH值会延长其到达稳定期的时间.此外,70℃高温和全铁质量浓度为38.9 g·L-1的高铁体系能促进生成黄钾铁矾和少量单质硫沉淀,而菌株能在pH值小于0.9时将大部分S0氧化为SO₄2-.      

新疆托克逊县科克乃克硫铜矿地质特征及控矿地质因素与找矿标志

科克乃克含铜黄铁矿位于米什西沟-科克乃克沟一带,赋矿基岩主要为志留系阿哈布拉克组石英角斑岩。矿区含矿岩石中的金属矿物主要为黄铁矿、黄铜矿、褐铁矿,次为氧化铜,孔雀石。含矿岩石结构:细晶、变晶结构,构造:主要为致密块状构造、星散浸染状构造、星点状构造、浸染状构造和少数网脉状构造,氧化矿有似层状与土状构造,矿床类型为角斑岩型含铜黄铁矿型多金属矿床。找矿标志为受热液蚀变的石英角斑岩,以及在地表为氧化后的黄铁矿所形成的黄钾铁矾化。     

磨矿和浮选过程中黄铁矿电化学行为的研究进展

综述了黄铁矿在选矿过程中有关的电化学行为及工作机理,重点讨论了黄铁矿结构特性、溶液中氧化、金属离子作用和抑制剂对黄铁矿电化学行为的影响;此外,还讨论了磨矿过程中电偶相互作用、研磨介质形状、介质材料和研磨气氛对研磨中黄铁矿电化学行为的影响。其中黄铁矿晶体结构的不同对黄铁矿表面的氧化具有较大影响,从而间接的影响黄铁矿的可浮性,半导体性质对黄铁矿的导电率具有显著的影响;同时适度的氧化有利于黄铁矿的无捕收剂浮选,而强烈的还原电位或氧化电位会抑制黄铁矿的浮选;电位的增加,对铜活化黄铁矿有不利影响,主要原因是电位增加导致活化Cu+的浓度降低,同时黄铁矿表面被铁氧化物覆盖阻碍了铜离子的吸附。抑制剂的加入可以直接参与捕收剂与黄铁矿之间的氧化还原反应,从而抑制黄铁矿的浮选;同时磨矿介质及气氛条件的不同也会影响黄铁矿电化学行为。      

长坑金矿选矿工艺试验研究

长坑金矿矿石属于以黄铁矿为载体的次显微结构难选难浸金矿石。对该矿矿石进行了浮选、催化预氧化-氰化、焙烧氧化-氰化、碱浸预氧化-氰化等工艺试验研究,为选矿工艺方案的确定指明了方向。     

用交流电处理丁基黄药

我矿属于锡石一硫化铅锌矿床,矿石分为硫化致密块状、氧化致密块状、硫化细脉浸染和氧化细脉浸染等四种类型,致密块状为主矿体,细脉状矿石在围岩中呈网状和星点状产出。主要金属矿物品位:Sn0.2～0.3%;Pb1.5～2.5%;Zn1.0～1.8%;还有少量黄铁矿和毒砂。脉石矿物有碳质页岩、砂岩、砂岩夹页岩、煌斑岩、石英等。     

紫外线诱变获得耐极低pH的氧化亚铁硫杆菌突变株

一株自某金矿分离纯化而得到的最适pH2 0的氧化亚铁硫杆菌(Acidobacillusferrooxidans),经紫外线诱变处理、定向筛选后获得最适pH为1 2～2 0、且可在pH0 6的条件下生长的突变株。该菌株经过八代接种培养后氧化活性稳定。两菌株诱变前后的形态及生理特性比较表明,该诱变菌株为一氧化亚铁硫杆菌的变种。     

Attachment of acidophilic bacteria to solid surfaces: The significance of species and strain variations

Sixteen strains of acidophilic bacteria were screened for their abilities to adhere to pyrite ore, glass beads and ferric hydroxysulfates. These were three culture collection and two isolated strains of the iron- and sulfur-oxidizer, Acidithiobacillus ferrooxidans, two each of the sulfur-oxidizer Acidithiobacillus thiooxidans and the iron-oxidizer Leptospirillum ferrooxidans (the type strain and a mine isolate in either case), five heterotrophic acidophiles (four Acidiphilium and one Acidocella sp.) and two moderately thermophilic iron/sulfur-oxidizers (Sulfobacillus thermosulfidooxidans and Sulfobacillus acidophilus). Considerable variations were found between different species of acidophiles, and also between different strains of the same species, in how they attached to the three solid materials tested. Attachment to the solid substrata generally increased with time (over 100 min) though > 99% of one At. ferrooxidans isolate (strain OP14) were attached to pyrite after just 10 min exposure. Most acidophiles attached more readily to pyrite than to glass beads, and attachment to ferric hydroxysulfates was highly variable, though one At. ferrooxidans isolate (strain SJ2) and one heterotrophic acidophile (Acidocella sp. het-4) both attached strongly to ferric iron precipitates (jarosites and schwertmannite) that formed in cultures of At. ferrooxidans grown at pH > 2. The results of these experiments showed that even closely related strains of acidophilic bacteria can display very different propensities to attach to solid materials, an observation that may explain the somewhat disparate results reported on occasions by research groups that have examined single, or limited numbers of strains, of acidophiles (mostly At. ferrooxidans). The significance of differential attachment of mineral-oxidizing and other acidophiles to pyrite and other solids is discussed in the context of biohydrometallurgy.     

A Visual Insight into the Oxidation of Sulfide Minerals During Bioleaching and Chemical Leaching of a Complex Ore

A scanning electron microscope (SEM) study was performed to provide a visual insight into the oxidation patterns of sulfide minerals during chemical and bacterial leaching of a complex ore for 3 days. The mineral grains were studied under SEM before and after bacterial and chemical leaching with or without the addition of ferrous iron to generate ferric iron in situ by bacteria or chemical oxidant (MnO₂). Both mesophilic and moderately thermophilic cultures of bacteria were used in bioleaching tests. A limited oxidation of sphalerite and pyrite, similar to those in acid leaching (control), was observed to occur when no ferrous iron was added. However, the initial addition of ferrous iron into bioleaching media was shown to significantly improve the oxidation of sphalerite and pyrite. Galena was readily oxidized in the presence or absence of bacteria. Sphalerite was oxidized more extensively/selectively than chalcopyrite and pyrite, consistent with their respective nobility/electrochemical activity. Provided that chemical/biological oxidation of sphalerite was intensive, a sulfur-rich layer appeared to form on mineral surface. But, no such layer on pyrite surfaces was discernable. Supplementary bioleaching data were also provided to support SEM observations and to further elucidate the bioleaching characteristics of these sulfide phases. It can be inferred from this study that the oxidation of sulfides proceeds most discernibly via “indirect mechanism” and the generation of ferric iron by bacteria in sufficient quantity is essential for the effective oxidation of sulfide minerals.     

pH对中度嗜热混合菌氧化载金黄铁矿生物氧化的影响

以载金黄铁矿为研究对象,研究pH值对中度嗜热混合菌氧化载金黄铁矿的影响.载金黄铁矿生物氧化过程中由于载金黄铁矿氧化溶解产酸使生物氧化体系不断下降,经过5 d搅拌氧化pH值已降至0.9左右,低于中度嗜热菌的最适生长pH值,抑制微生物的生长和载金黄铁矿生物氧化.控制生物氧化体系的pH值至1.2和1.6使铁离子浓度从13.08 g/L增大至15.75 g/L和13.58 g/L, 控制载金黄铁矿生物氧化体系pH值至1.2显著促进载金黄铁矿生物氧化.XRD分析结果表明:中度嗜热菌氧化载金黄铁矿过程中不生成黄钾铁矾和单质硫等产物.      

Alterococcus agarolyticus, gen.nov., sp.nov., a halophilic thermophilic bacterium capable of agar degradation

Five strains of facultatively anaerobic moderately thermophilic bacteria were isolated from two hot springs in the intertidal zone of Lutao, Taiwan. They produced extracellular agarase on agar medium, yielding reducing sugars and organic acids as the end products under either aerobic or anaerobic conditions. The growth temperature range was approximately 38-58 degrees C with an optimal temperature of about 48 degrees C. The five strains tolerated a relatively narrow pH range from 7.0 to 8.5. They were Gram-negative halophiles growing optimally at 2.0-2.5% NaCl (ca. 0.34-0.43 M). They were capable of anaerobic growth by fermenting glucose and producing various organic acids such as butyrate, propionate, formate, lactate, and acetate. Cells grown in liquid medium were motile monotrichous cocci, normally 0.8-0.9 micron in diameter. They possessed saturated anteiso-15-carbon acid (anteiso-C15:0) as the most abundant cellular fatty acid (46.0-51.3 mo1%) and had G + C contents ranging from 65.5 to 67.0 mo1%. They are the first thermophiles found to degrade agar and also the first halophilic thermophilic bacteria known to be capable of both aerobic and anaerobic fermentative growth. These bacteria are considered to represent a new genus that we named Alterococcus, and Alterococcus agarolyticus is the type species.     

Use of mesophilic and thermophilic bacteria for the improvement of copper extraction from a low-grade ore

Bioleaching was examined for copper extraction from a low grade ore using mesophilic and moderate thermophilic bacteria. Five equal size columns were used for the leaching of the ore. Sulfuric acid solution with a flow rate of 3.12 L.m-2.h-1 and pH 1.5 passed through each column continuously for 90 d. In the first and the second column, bioleaching was performed without agglomeration of the ore and on the agglomerated ore, respectively. 28wt% of the copper was extracted in the first column after 40 d, while this figure was 38wt% in the second column. After 90 d, however, the overall extractions were almost the same for both of them. Bioleaching with mesophilic bacteria was performed in the third column without agglomeration of the ore and in the fourth column on the agglomerated ore. After 40 d, copper extractions in the third and the fourth columns were 62wt% and 70wt%, respectively. Copper extractions were 75wt% for both the columns after 90 d. For the last column, bioleaching was performed with moderate thermophilic bacteria and agglomerated ore. Copper extractions were 80wt% and 85wt% after 40 and 90 d, respectively. It was concluded that crushing and agglomeration of the ore using bacteria could enhance the copper extraction considerably.     

生物冶金中浸矿微生物的研究现状

总结了国内外主要浸矿微生物种类,分析了嗜中温细菌、中度嗜热细菌、中度嗜热古生菌和极端嗜热古生菌等嗜酸菌种及嗜碱菌种的生存习性、培养特点和浸矿能力,评述了浸矿微生物的物理、化学及生物改良方法的特点和适用性,以及多种菌属联合浸出、异养微生物浸出和浸矿生物反应器等高效强化浸出方法。     

Biochemistry of sulfur extraction in bio-corrosion of pyrite by Thiobacillus ferrooxidans

By adding a small amount of the amino acid cysteine to an acidic solution containing Thiobacillus ferroxidans cells and subsequent incubation with synthetic pyrite layers, the duration of the lag phase in the growth of T. ferrooxidans is minimized and the leaching rate of this sulfide is increased three times compared to the normal process without this biochemical additive.In the presence of cysteine, pyrite can be oxidized in the absence of bacteria with a leaching rate comparable with that attained by bacteria under normal leaching conditions.It seems that the sulfhydryl group of cysteine participates in a binding process with pyrite. Free-SH groups from the pyrite surface would be the counterpart for the formation of the corresponding disulfide. This thiol-disulfide reaction means that cysteine is consumed by the pyrite surface with the subsequent release of iron-sulfur species. This result is accounted for by the fact that pyrite without bacteria can be completely oxidized. Bacteria would take advantage of this biochemical corrosion process by uptake and oxidation of the released species which are continuously supplied to the acidic-biotope.The reactivity of cysteine with the pyrite surface, which improves the bacterial leaching rate, suggested the investigation of other mono-thiol molecules with the aim to mask the pyrite surface against bacterial attack. The latter can be relevant for protecting steel against microbiologically induced corrosion (MIC). S-tert-butyl mercaptan ((CH₃)₃C–SH, TBM)) was found to stop the bacterial corrosion by T. ferrooxidans. Permanent disulfide bonds between pyrite and the blocking SH-agent are presumably the cause for this protection.     

Utilisation of native microbes from a spent chalcocite test heap

A variety of acidophilic iron and/or sulphur-oxidising microbes capable of growth on several substrates (chalcopyrite, pyrite, ferrous ion, sulphur, glucose) in the range 30–60 °C were recovered from a spent chalcocite/chalcopyrite/pyrite heap. Several isolates exhibited tolerance to salt, up to 5 g/L NaCl, and to the metals nickel, cobalt, zinc and copper at up to 50 g/L.Leaching tests on chalcopyrite concentrate indicated higher copper yields when native isolates were employed, compared with the laboratory reference strains Acidithiobacillus ferrooxidans (DSM 583) and Sulfobacillus thermosulfidooxidans (DSM 9293). After 30 days, several native isolates had leached 20–30% more copper than the abiotic controls during experiments conducted at 45 °C. The results demonstrate that the native isolates are potential bioleaching candidates, adapted to diverse growth conditions.     

Bacterial leaching of low-grade ZnS concentrate using indigenous mesophilic and thermophilic strains

In this study low-grade sphalerite has been treated by the bioleaching process using native cultures of Acidithiobacillus ferrooxidans and Sulfobacillus thermosulfido-oxidans in order to determine the ability of these bacteria to the leaching of zinc. The effects of bacterial strain, pH, temperature, pulp density, iron precipitation, and initial concentration of ferric iron on the zinc leaching were evaluated. The bioleaching experiments were carried out in shake flasks at pH 1.5, 180 rpm, 33 °C and 60 °C for mesophilic and thermophilic bacteria, respectively. Compared with the use of laboratory reference strains or control conditions, zinc recovery from the respective concentrate was greater when native isolates were employed. The experimental data show that the selection of the suitable pH and temperature during the bioleaching processes would be important. The results indicate that the increase in pulp density generates a decrease in the dissolved zinc concentration. The maximum zinc extraction reached was 87% using native thermophile S. thermosulfido-oxidans culture after 30 days.     

Heap Biooxidation - Bioleachingofa Refractory Gold-Bearing Ore

Abstract

A refractory pyrite/arsenopyrite ore containing 3.7 g/ton of gold finely disseminated in the sulphide matrix was subjected to microbial leaching in a heap containing 120 tons of ore crushed to minus 15 mm. The ore was initially leached by means of acidophilic chemolithotrophic bacteria to oxidize the sulphide minerals and to liberate the gold. About 50% of the sulphide sulphur was oxidized within 90 days. Previous laboratory experiments had shown that such degree of sulphide oxidation resulted in a high gold extraction during the subsequent leaching of the pretreated ore. After the bacterial pretreatment the ore was washed with water and was treated by alkaline solutions until the pH of the heap effluents was established in the range of 9- 10. Then the leaching of the gold was started with solutions containing amino acids of microbial origin and thiosulphate as gold-complexing agents as well as some ions participating in the oxidation and/or complexation of the gold. 70.7% of the gold was leached within 12 days in this way. Silver was leached together with gold. The pregnant solutions were treated by cementation with metallic zinc to precipitate the dissolved precious metals.