The bioleaching and processing of refractory gold ore

Technological advances have taken biooxidation from a concept to commercial reality. The understanding and funding of bench, pilot, and full-scale programs is steadily increasing. Today, biooxidation technology is successful in a range of conditions, from ideal to the most severe climates in the world. Because of this flexibility, biooxidation can be effectively integrated into gold-processing mills to achieve economical recovery from refractory ores. Nicholas S. Lynn earned his M.Sc. in chemical engineering at the University of Denver in 1970. He is currently president of Lyntek.     

Thermodynamics and technology of extracting gold from low-grade gold ore in system of NH4Cl-NH3-H2O

1 Introduction Hydrometallurgy with ammoniacal ammonium chloride as extracting system is a new developing field with many merits. Above all, NH3 and Cl- ions existing in the system have relatively high complex ability with some heavy or noble metal ions. …     

Characterizing the distribution of gold in pyritic sulfide ore

Auriferous pyrite is an important ore in the Green’s Creek polymetallic-sulfide deposit. Pyritic ores have textural and crystal forms that range from primitive framboidal spherules to euhedral crystals. The gold associated with the pyrite at Green’s Creek is found in concentrations at the ppmw level and necessitates the use of secondary ion mass spectrometry. The results presented in this article show gold is distributed in two ways: finely dispersed throughout a pyrite matrix and concentrated as native gold or as electrum at grain edges or along fractures. Finely dispersed gold is found in pyrite spherules and porous masses, whereas the gold “nuggets” are found in association with the crystalline pyrite. An association between gold and arsenic is observed, but the association is complex and is not necessarily congruent. The results suggest that during the maturation of pyrite containing finely dispersed gold, gold is mobilized and ultimately concentrated at grain edges as nuggets. For more information, contact Allen Pratt, CANMET Mining and Mineral Sciences Laboratory, Natural Resources Canada, 555 Booth Street, Ottawa, Canada K1A 0G1; (613)992-1376; fax (613)996-9673; e-mail apratt@NRCan.gc.ca.     

Valence variation of arsenic in bioleaching process of arsenic-bearing gold ore

The concentration and variational trend of As3+ and As5+, the bacterial resistance for the As3+ and As5+ and converting conditions from As3+ to As5+ were analyzed. The additive was used to prompt the bacterial leaching efficiency by changing valence state of arsenic. The results show that the concentration of As3+ is larger than that of As5+ in the lag phase. The concentration of As3+ decreases in the log phase, and is lower than that of As5+. HQ-0211 typed bacteria express better resistance for As3+ and As5+ and remain growing when the concentrations of As3+ and As5+ are above 6.0 g/L and 12.0 g/L, respectively. It is found that Fe3+ cannot oxidize As3+ singly as strong oxidant in the leaching system, but can cooperate with pyrite or chalcopyrite to do that. The oxidation of As3+ is prompted with addition of H2O2. The bacterial activity is improved in favor of bacterial leaching efficiency. NaClO restrains the bacterial growth to depress leaching efficiency because of the chloric compounds affecting bacterial activity.     

滨海大型金矿床取消矿柱及房柱交替采矿的新工艺

针对三山岛金矿条件,研究了深部开采取消点柱的工艺技术。首先,调查测试了矿岩物理力学参数,并对矿岩质量进行了分级。其次,在详细分析上下盘及矿体的物理力学特性的基础上,对三山岛金矿深部开采取消矿柱进行了有限元数值模拟,研究得出-555m水平以下矿体的开采可全面取消矿柱。最后,结合矿床条件,提出了房柱交替式盘区上向分层充填采矿新工艺。工业试验结果显示,该新工艺大幅度提高了单位面积开采强度,对岩层扰动小,盘区生产能力大,矿石损失贫化小,获得了显著的经济效益。此外,对三山岛金矿由于深部开采而导致的地表沉降利用ANSYS软件进行分析,同时对岩层变形进行了监测。结果表明,三山岛金矿深部开采取消矿柱和采用房柱交替采矿新工艺后能够有效控制岩层变形,从而可实现滨海大型金矿床安全高效低贫损开采。     

Simultaneous extraction of gold and zinc from refractory carbonaceous gold ore by chlorination roasting process

A novel process based on chlorination roasting was proposed to simultaneously recover gold and zinc from refractory carbonaceous gold ore by using NaCl as chlorination agent. The effects of roasting temperature, roasting time and NaCl content on the volatilization rates of gold and zinc were investigated. The reaction mechanism and the phase transition process were also analyzed by means of SEM, EDS and XRD. The results demonstrated that under the optimal conditions of NaCl content of 10%, roasting temperature of 800 °C, roasting time of 4 h and gas flow rate of 1 L/min, the rates of gold and zinc were 92% and 92.56%, respectively. During low-temperature chlorination roasting stage, a certain content of sulfur was beneficial to the chlorination reactions of gold and zinc; and during high-temperature chlorination roasting stage, the crystal structure of vanadium-bearing mica was destroyed, and the vanadium-containing oxides were beneficial to the chlorinating volatilization of gold and zinc. Eventually, the chlorinated volatiles of gold and zinc could be recovered by alkaline solution.     

新疆某金矿浮选药剂优化试验研究

新疆某金矿石金品位为2.30 g/t,硫品位为0.8%,属于低硫含金矿。自然金的嵌布粒度微细,主要被石英或其他脉石包裹,采用阶段磨矿、阶段选别回收金。在原有浮选工艺的基础上,开展调整剂、捕收剂种类及用量的优化试验研究。结果表明,在与现场两段磨矿细度相同的条件下,采用一优一粗二精两扫的闭路浮选流程,异戊基钠黄药作为捕收剂时,获得混合精矿产率为6.21%,金品位34.10 g/t,回收率为90.61%。     

The process mineralogy of gold: The classification of ore types

The principal gold minerals that affect the processing of gold ores are native gold, electrum, Au-Ag tellurides, aurostibite, maldonite, and auricupride. In addition, submicroscopic (solid solution) gold, principally in arsenopyrite and pyrite, is also important. The main causes of refractory gold ores are submicroscopic gold, the Au-Ag tellurides, and very fine-grained gold (<10 μm) locked in sulfides. Other types of problem gold ores include copper-gold ores and preg-robbing carbonaceous ores. J.P. Vaughan is associate professor and head of the Mining Geology Program at the Western Australian School of Mines, Curtin University of Technology, and carries out research in process mineralogy for the A.J. Parker Cooperative Research Centre for Hydrometallurgy, Perth, Western Australia.     

金矿生物预氧化中溶解氧浓度的变化及其影响

通气动力成本过高是含砷难处理金矿的生物氧化预处理法中存在的主要问题,在不同矿浆浓度、不同反应器条件下开展含砷难处理金矿生物氧化实验,重点监测反应体系中溶解氧浓度、氧化还原电位φ、pH和砷浓度的变化;采用5 L反应器开展不同矿浆浓度实验.结果发现:25％矿浆浓度实验中溶解氧浓度低至225μg/L,但其生物氧化过程仍可正常...     

河北某石英脉型金矿石选矿试验研究

河北某石英脉型金矿石金品位5.4 g/t,银品位6.4 g/t。针对该矿石性质,开展浮选试验,在最佳药剂制度条件下浮选闭路试验获得精矿金回收率为78.9%,银回收率35.6%,金品位44.0 g/t,银品位23.5 g/t。为提高选矿指标,开展重选与浮选工艺联合试验。与单一浮选工艺相比,重、浮联合工艺获得混合精矿金回收率提高6.8%,银回收率提高2.2%。     

某厂含锑金矿浮选工艺改进研究

国内某厂含锑金矿的选矿回收率偏低。为提高选矿回收率,有效利用矿产资源,增加企业经济效益,进行了磨矿细度、浮选药剂捕收剂、抑制剂、活化剂种类和用量的实验研究。结果表明,在磨矿细度为-0.045 mm粒级占93.52%,抑制剂焦亚硫酸钠+新型药剂GT-1用量(200+200) g/t,活化剂硝酸铅用量400 g/t,捕收剂丁基钠黄药用量500 g/t、乙硫氮200 g/t,新型药剂GT-2用量400 g/t,起泡剂2^#油用量30 g/t条件下,经一粗四扫三精浮选闭路流程,锑回收率达77.33%,金回收率59.16%。结合闭路试验结果,对工业选矿生产流程进行了优化改进,技术指标提升明显。     

Bioleaching of refractory gold ore （ Ⅲ ）——Fluid leaching Jinya refractory gold concentrate by Thiobacillus ferrooxidans

A novel fluidized-bed reactor was designed and installed for bloleaching in a semi-continuous way, by which a process for biuleaching-cyanidation of Jinya refractory gold arsenical concentrate was studied. The arsenic extraction rate reaches 82.5 % after 4-day batch biooxidation of the concentrate under the optimized condition of pH 2.0, ferric ion concentration 6.Sg/L and pulp concentration 10%. And leached rate of gold in the following cyanida.tion is over 90%. The parameters of three series fluidized-bed reactors exhibit stability during the semi-continuous bioleaching of the concentrate.Armmic in the concentrate can be got rid of 91% after 6-day leaching. Even after 4 days, 82% of arsenic extraction rate was still obtained. The recovery rates of gold are 92 % and 87.5 % respectively in cyaniding the above bioleached residues.The results will provide a base for further commercial production of gold development.     

Structure/processing relationships in the fabrication of nanoporous gold

Nanoporous gold made by dealloying silver/gold alloys is a relatively new material finding application in catalysis, sensing, and other areas. Here we discuss the metallurgical processing required to make patterned foils of nanoporous gold with large, flat grains, with which we are exploring an application as substrates for the heterogeneous nucleation of protein crystals.     

The design-of-experiment optimization and development of cobaltite ore mineral processing

Laboratory testing, plant optimization, and the interpretation and application of metallurgical technologies can be tedious, time consuming, and costly. This paper outlines the use of proven statistical design-of-experimentation software for rapid laboratory testing and optimization of mineral processing of cobaltite ore with limited representative sample utilization. Editor's note: Owing to the way commodities are traded, all measurements are presented in standard units rather than metric units.     

Advancements in MEMS materials and processing technology

From achievements in display imaging to air bag deployment, microelectromechanical systems are becoming more commonplace in everyday life. With an abundance of opportunities for innovative R&D in the field, the research trends are not only directed toward novel sensor and actuator development, but also toward further miniaturization, specifically achieving micro- and nanoscaled integrated systems. R&D efforts in space, military, and commercial applications are directing specific research programs focused on the area of materials science as an enabling technology to be exploited by researchers and to further push the envelope of micrometerscaled device technology. These endeavors are making significant progress in bringing this aspect of the microelectro-mechanical field to maturation through advances in materials and processing technologies. John D. Olivas earned his Ph.D. in mechanical engineering and materials science from Rice University in 1996. He is currently a program element manager and staff engineer senior for the Advance Interconnect and Manufacturing Assurance Program at the Jet Propulsion Laboratory. Stephen R. Bolin earned his M.S. in materials science from Stanford University in 1970. He is currently staff engineer senior and supervisor of the Applications Engineering Group in the Quality Assurance Office at the Jet Propulsion Laboratory.     

微成形技术在塑性加工中的应用研究

快速增长的MEMS市场为微系统工程提供了广阔的发展和应用空间,对微金属零件的需求也日益增多,结合微成形技术和传统塑性加工方法,可以提高微零件精度和生产率,实现批量生产,但是也对微成形技术和塑性加工提出了新要求.尺度效应的影响使得微塑性成形成为一个全新的领域,传统的塑性加工理论无法继续使用.本文在介绍微成形概念的基础上、对其在塑性加工中的应用、进展以及研究方法进行了分析总结,并阐述了相关的关键技术.