Understanding Gamsberg – A geometallurgical study of a large stratiform zinc deposit

The Gamsberg zinc deposit in the Northern Cape in South Africa has been the subject of a number of studies by Anglo American over the years. Two distinct ore types have been identified, namely pelitic and garnet-magnetite ore. The ore is characterised by relatively high manganese levels. Manganese reporting to the flotation concentrate is problematic for downstream refining.Anglo Research was asked by the exploration division of Anglo Base to study the relationship between the mineralogy and the floatability of the ore from reef intersections obtained from the eastern ore body. The two ore types were found to have different mineralogical characteristics resulting in different flotation responses both in terms of zinc and manganese recoveries and concentrate grades.The presence of the manganese sulphide, alabandite, was also established, and was found to be extremely detrimental to sphalerite flotation. The reasons for this were explained using the surface analysis facility at Anglo Research.     

Hydrometallurgical processing of Platreef flotation concentrate

Platinum producers are evaluating hydrometallurgical process routes to extract platinum group metals (PGM) and base metals (BM) from flotation concentrate that are alternative to conventional pyrometallurgical matte smelting treatment of flotation concentrates. This approach would attract several potential benefits to the cost-effective processing of lower-grade and high-chromium concentrates. Ivanhoe Nickel and Platinum Ltd. wished to investigate this option on samples arising from their Platreef project in the northern limb of the Bushveld Complex in South Africa, from concentrate containing 1.5 g/t Pt, 2.5 g/t Pd and 0.5 g/t Au, as well as 1.5% Ni and 1.2% Cu. Other PGMs assayed rather low grades in the concentrate (Rh 128 ppb; Ru 153 ppb; Os 18 ppb; Ir 31 ppb) so the focus was on Pt, Pd and Au in this study. Some twenty-two hydrometallurgical process flowsheet variants were considered for evaluation in a testwork programme combining several conventional and proprietary unit process technologies.The testwork outcomes suggested that a hydrometallurgical flowsheet alternative to smelting (the patented Kell Process) is potentially a practical, environmentally benign and energy-efficient approach for treating low-grade Platreef concentrate with relatively low risk. This process broadly comprises selective leaching of base metals by pressure oxidation, followed by leaching of PGMs after a roasting pretreatment step shown to render PGMs and particularly Pt amenable to leaching. The process embodies separation of the value metals (PGM and base metals) into separate chloride and sulfate solution streams, respectively, and impurity elements (Fe, Al and gangue) into a tailings product. Key elemental deportments from the un-optimized process were Ni 96%, Co 94%, Cu 94%, Pt 96%, Pd 94% and Au 87%.Preliminary work indicated that further improvements in value metal recoveries, impurity separations and reagent consumptions may be gained from further optimization of the individual unit processes. Moreover, the recycle of key reagents uses existing proven technologies, rendering the process more economically and environmentally favourable. Initial assessment suggests that the Kell Process should offer both economic and environmental benefits over conventional pyrometallurgical matte smelting treatment of Platreef flotation concentrate.     

The value of automated mineralogy

Automated mineralogy methods and tools, such as the Mineral Liberation Analyser (MLA) and the QEMSCAN, are now widely used for ore characterization, process design and process optimization. Several case studies published recently demonstrate that large gains can be obtained through grinding and flotation optimization guided by automated mineralogy data. However, since automated mineralogy can only provide the information pointing to where the process gains can be made, it does not directly impact the production gain. Thus the question is often asked: how to value the contribution of automated mineralogy to process improvement at a particular plant. This appears to be a difficult question to answer. On close examination however, it is found that this is essentially a question of the value of information and this is reasonably well documented in various other industries. Hubbard, 2010, in chapter 7 “Measuring the Value of Information”, dealt with exactly this type of problem. The value of information is the reduced risk of an investment and opportunity loss. The methods Hubbard developed can be applied to estimate the value of automated mineralogy, as well as metallurgical test work, both producing information that reduces the risk of investment.This paper first introduces Hubbard’s theory on the value of information and how to measure it. It then applies his methods to estimate the value of automated mineralogy, using Anglo Platinum’s fine grinding project as an example. In the end, a general model is developed to allow the simulation of the value of automated mineralogy in different mining operations constrained by different parameters.     

辽西某钒钛磁铁矿工艺矿物学研究

通过X射线衍射、矿相显微镜和扫描电子显微镜等技术手段,对辽西某钒钛磁铁矿进行了工艺矿物学研究。结果表明:矿石中磁铁矿含量很少,铁矿物主要为假象赤铁矿,钛铁矿是主要的钛矿物,脉石矿物以长石和辉石为主;矿石中大部分钒钛磁铁矿发生了假象赤铁矿化而导致其磁性变弱;钒钛磁铁矿晶格中普遍存在以类质同象的形式存在的Ti O2等成分,且部分钒钛磁铁矿发生了不同程度的榍石化,可能使铁精矿具有"高钛低铁"的特点。根据工艺矿物学特点,该矿石宜在精选作业前先采用重选、磁选等高效、低成本的工艺进行预处理,以减小矿石的处理量;该矿的铁精矿宜采用非高炉法进行冶炼。     

铜冶炼渣直接还原焙烧—磁选回收铜、铁试验研究

铜冶炼渣中含有铜、铁等有价金属,其中铜金属可通过直接浮选回收,但铁的矿物组成复杂,很难直接通过磁选回收。以含铁38.76%、含铜2.26%的铜冶炼渣为研究对象,在矿石性质研究基础上,以烟煤为还原剂,通过直接还原焙烧—磁选工艺回收铜渣中的铜、铁。结果表明,铜冶炼渣、烟煤和还原助剂氧化钙以100∶25∶20的质量比混合,在焙烧温度1 200 ℃,焙烧时间80 min的条件下直接还原焙烧铜渣;焙砂在磨矿细度为-0.045 mm含量占80%,磁场强度为111 kA/m的条件下进行磁选试验,最终可获得铁品位为91.54%,铁回收率为90.54%,铜品位为6.06%、铜回收率为89.04%的含铜铁精矿,研究结果可为铜冶炼渣的回收利用提供依据。     

Influence of liberation on bubble–particle attachment time in flotation

Flotation is controlled by the bubble–particle attachment mechanism which depends on the particle surface properties i.e., the particle composition, the surface liberation of valuable minerals and collector adsorption. This paper focuses on using the bubble–particle attachment method to understand the factors affecting attachment time. The attachment time measurements were performed with sized concentrates obtained by flotation of a copper sulphide ore (Northparkes Mine, Australia) in a mechanically agitated batch flotation cell. Quantitative mineral liberation analysis was used to determine the mineralogy of flotation concentrates. The results showed that the higher the amount of highly and moderately liberated copper minerals in flotation concentrates, the lower the attachment time. By using attachment time and collector dosage, we defined a non-linear empirical correlation to estimate Cu grade. The proposed empirical correlation has shown a satisfactory agreement between the calculated and the experimental Cu grade. These results showed that attachment time measurements are related to the Cu grade. This relationship may be used in the future to develop a practical method (without assays) to monitor changing grade for a specified system (flotation plant). It also may be possible to infer potential grade if mineralogy samples are available, but not enough samples are available for conventional flotation tests. However this requires a significant amount of further work.     

工艺矿物学在矿产资源找矿和综合利用中的应用

自上世纪七十年以来,工艺矿物学经大量科学实践,已逐渐发展成为一门较为成熟的实验科学。工艺矿物学通过揭示矿石中矿物间相互关系的内在规律,针对工业利用的主要对象矿石,进行定量分析,测定各元素在矿石中的赋存状态及各元素之间的相互关系,集中和分散系数及矿物工艺粒度,为选矿工艺流程制定提供定量的基础资料以及在选矿工艺流程试验中追踪目的矿物的走向和分布规律,解释选矿工艺流程的合理性;在冶炼火法、湿法冶金工艺中及时追踪元素的走向和分布规律,运用热力学原理和矿物相变机理,较精确地提供工艺要求的各项参数,以使冶炼工艺更加合理,并为选冶联合工艺中新方法、新技术的研究提供指导性的基础资料。     

某复杂铜铅锌银多金属硫化矿的综合回收试验研究

某复杂铜铅锌银多金属矿富含多种有价金属元素,但有用矿物嵌布粒度细且不均匀,嵌布关系十分复杂。工艺矿物学研究表明铜矿物主要为黝铜矿,且大部分的银以类质同象赋存在该矿物中,在国内实属罕见。本试验采用优先浮选流程再结合中南大学新型铜捕收剂MT-20及铅捕收剂BITCM,获得了铜精矿品位为18.18%、回收率为81.03%,铅精矿品位为55.56%、回收率为72.63%的工艺指标。全流程闭路试验结果表明该工艺操作方便,指标稳定,各有价金属回收率高,达到了综合回收目的。     

赞比亚某铜冶炼渣选铜试验

为高效开发利用赞比亚某铜冶炼渣，以赞比亚某铜冶炼渣为研究对象，通过对试样化学成分及工艺矿物学特点的分析，确定采用浮选法回收其中的铜。经过2粗开路流程试验，确定了以黄药粒为捕收剂，T 336为起泡剂，硫化钠及水玻璃为调整剂的浮选药剂制度；最终采用1粗3精2扫、中矿顺序返回的闭路浮选流程处理试样，获得了铜品位17.32%、回收率82.78%的铜精矿。试验对该类型铜冶炼渣的选矿处理提供了有益参考，经济效益显著。     

Optical analysis of particle size and chromite liberation from pulp samples of a UG2 ore regrinding circuit

Since the early seventies high chromite and low base metal sulphide (BMS) contents of the UG2 reef imposes technological challenges to mineral processors and extractive metallurgists. Forty years later, particle size distribution and size by size mineralogy are considered as key factors to the continuous improvement of the UG-2 ore metallurgy. With the successful development of ultra fine grinding technologies, a compromise has to be found between fine grinding to achieve platinum group minerals liberation and to avoid the overgrinding of gangue minerals, especially chromite gangue which is detrimental in smelting process. Indeed, fine chromite grains, despite of being naturally hydrophobic mineral, can be recovered in flotation concentrate by entrainment. In addition, overgrinding also increase liberation of naturally floatable gangue (talc) which contaminate the concentrate and need to be controlled during flotation.In this paper, innovative techniques of single particle image analysis from both dry and wet samples have been tentatively used to assess the chromite particle size distribution and the chromite grade of samples taken from a secondary milling circuit. Preliminary results demonstrate excellent potential for online particle imaging making use of both the particle geometry (size, shape) and the optical properties (translucency).     

Process mineralogy of fluorosilicate minerals in ok tedi ores

The impact of fluorine in copper flotation was relatively unknown until the introduction of skarn ores in the Ok Tedi concentrator. Fluorine in the copper concentrates reports to the gas phase during the smelting stage and forms a corrosive H₂SO₄-HCl-HF acid brine mixture which must be neutralised.This work was aimed at studying the mineralogy of the fluorosilicate minerals contained in the various oretypes present in the Ok Tedi porphyry copper deposit. The electron microprobe was used to analyse for fluorine and hence identify the fluorosilicate minerals in each oretype. This study revealed talc, phlogopite, biotite, clays, amphiboles, fluoroapatite and titanite to be the sources of fluorine in the orebody.Laboratory and plant investigations were conducted to study the flotation response of these minerals. Chemical assaying of the products of these tests was done to determine the bulk assay of fluorine. Using Rietveld analysis, quantitative estimates of the fluorosilicate minerals in these products were generated. Marrying of the bulk assay with the respective mineralogical “assay” enabled the understanding of the flotation behavior of fluorine and it's associated mineralogy. Talc and phlogopite were found to be the causes of the fluorine problem at Ok Tedi.     

废铅酸蓄电池胶泥的低温熔盐还原固硫熔炼工艺研究

提出了一种废铅酸蓄电池胶泥低温熔盐还原固硫熔炼新工艺, 该工艺以次氧化锌作固硫剂, 焦粉为还原剂, 在800～900 ℃的工业纯碱熔体中还原熔炼废铅酸蓄电池胶泥, 实现了再生铅的低温、低碳、清洁冶炼。在理论分析的基础上, 研究了工艺条件对熔炼过程的影响。结果表明, 在纯碱质量为固态物的2.835倍、固硫剂为理论量的1.1倍、还原剂为胶泥的16%、熔炼温度为880 ℃的最优条件下, 获得很好的冶炼指标: 铅的直收率和总回收率分别为96.64%和98.06%, 氧化锌固硫率为94.70%。新工艺具有低温、低碳、低耗、高效、清洁和过程简单等优点, 对废铅酸蓄电池胶泥及铅烟尘等再生铅原料的清洁冶炼和原生铅(锑、铋)的清洁冶金均具有重要意义。     

金川铜镍矿贫矿石选矿产品的工艺矿物学研究

通过对金川铜镍矿某矿区正在试产的贫矿石现场流程的精矿、尾矿样品的工艺矿物学研究发现,主要存在的问题是精矿Ni、Cu品位低,MgO含量高。其主要原因是滑石易浮,大量在精矿中富集造成的。因此,要提高铜镍品位,降低精矿中MgO的含量,适当提高铜镍的回收率,最直接有效的方式是降低精矿中滑石的含量。     

复杂锌精矿沸腾焙烧的行为研究

随着国内锌资源的不断匮乏以及市场的快速变化,锌冶炼企业入选的锌精矿成分也越来越复杂,高硅、高铜、高铅、高铁矿源已逐渐成为常态,这些高杂质矿使得沸腾焙烧炉炉况严重恶化,极大影响焙烧工序的正常进行。锌冶炼企业要想在日益复杂的市场竞争中获得长足发展,除了需要以最低的成本组织生产外,还需要能够适应各种复杂矿源,特别是能够处理高附加值的锌精矿。因此本文对复杂锌精矿中的重点杂质Cu、Pb、SiO₂、Fe在沸腾焙烧中的行为以及影响进行了系统的研究,旨在为锌冶炼企业处理复杂锌精矿提供一定的理论与实践指导。     

选冶试验样品配制方法和检验

配样是开展选冶试验的基础,其合理性显著影响选冶试验结果的可靠性。文章探讨了选冶试验样品配制原则、程序和计算公式。选冶试验配样应遵照审阅地质资料和采样设计书、研究各样品的物质组成、制定配样方案、样品制备和检查配样合理性等五个步骤进行。在配样过程中,每一个编号样品所配入的样品质量应当与其代表的矿块储量成正比。配制的试验样品应与目标矿石性质一致,包括矿石品位一致、矿物组成一致、矿物原生粒度一致和岩石性质一致。混匀样品是避免抽样误差的关键因素。文章还介绍了样品混匀性检验的计算方法——方差分析法。      

艾萨炉铜熔炼烟道结渣的矿物学分析

艾萨炉铜熔炼过程中因烟道结渣造成刮板磨损严重,烟气流通受阻,影响生产效率和稳定性.从工艺矿物学角度,通过考察艾萨炉余热锅炉水平烟道产物中主要元素铜、铁、硫等的赋存状态,以及结渣的物相组成和结构特征,对烟道结渣原因进行分析.结果表明,烟道结渣中铁酸铜、赤铁矿、磁铁矿、冰铜及硅酸盐玻璃相含量明显偏高,且常以核的形式黏附并胶...     

澳大利亚布朗斯炭质页岩铜镍钴矿工艺矿物学研究

为了确定澳大利亚布朗斯地区炭质页岩铜钴镍矿资源合适的选矿工艺,对该地区有代表性矿样开展了工艺矿物学研究。结果表明:1矿石为典型的沉积型炭质页岩多金属矿,矿物组成复杂,主要金属矿物为黄铜矿、斑铜矿、硫钴镍矿等,矿石中钴、镍等有价元素以类质同象的形式或呈机械夹杂物分布于硫镍钴矿、黄铁矿及脉石矿物中,脉石矿物主要为炭质、白云母、多水高岭石等。2矿石中各矿物间共生关系复杂,普遍存在着交代结构和相互浸染构造,致使部分可浮性较好的炭质矿物易浮选进入硫化矿精矿中,同时部分微细粒硫钴镍矿被黄铜矿包裹,浮选时易进入铜精矿中。3矿石中黄铜矿和黄铁矿属中细粒嵌布范畴,硫镍钴矿属细粒—微粒嵌布范畴。根据矿石工艺矿物学特征,建议采用阶段磨矿—阶段选别的工艺依次回收铜、钴、镍、硫,尾矿可作为钾化肥。     

凡口铅锌矿选矿厂生产流程的工艺矿物学评价

为评价凡口铅锌矿选厂的浮选工艺 ,进行浮选流程考查 ,对主要产品进行了工艺矿物学研究。通过化学分析、铅锌物相分析、产品筛分水析以及在显微镜与扫描电镜下详查与测定 ,查明了原矿及主要产品的氧化程度、矿物组成、主要矿物的解离度 ,铅、锌、银及镓、锗等元素的赋存状态。文章指出 ,影响铅精矿、锌精矿质量的矿物主要是黄铁矿单体 ;细粒银矿物可浮性较差。因此 ,提高选矿指标的可能途径是加强对黄铁矿的有效抑制 ;若能找到适宜的药剂条件 ,提高银的回收率的潜力比较大。     

A mechanistic model to predict matte temperatures during the smelting of UG2-rich blends of platinum group metal concentrates

High matte temperatures can be related to numerous catastrophic furnace failures in the platinum group metal (PGM) industry where chromite-rich upper group 2 (UG2) concentrates are smelted. Chromite rich concentrates require high slag temperatures as well as sufficient mixing to suspend the chromite spinel particles in the slag and prevent settling in a so-called “mushy” layer consisting of a three phase emulsion of slag, matte and chromite particles. To achieve sufficient bath mixing and to melt and suspend chromite spinel build-up, high hearth power densities are utilised. However, high hearth power densities in conjunction with a heat-isolating concentrate layer, leads to high side wall heat fluxes which motivated the use of intensive cooling in the furnace side wall so that a slag freeze lining can be formed. If matte temperatures are above the slag liquidus temperature, any matte that comes into contact with the freeze lining can destroy the freeze lining. Moreover, if the matte temperature exceeds ca. 1500 °C, chemical thermodynamics indicate that matte has the ability to sulfidise MgO-Fe_xO-Cr₂O₃ refractories, leading to rapid wear of refractories exposed to high temperature flowing matte. Models are derived for the concentrate-to-matte and slag-to-matte droplet heat transfer. Calculations using the derived models, physical properties and furnace operating conditions give realistic matte temperatures and show that matte temperatures rapidly increase as the concentrate bed becomes matte drainage rate limiting. It is shown that for each concentrate blend mean particle size and mineralogy, there is a maximum smelting rate above which the concentrate bed becomes rate limiting with regards matte drainage, thereby significantly contributing to matte preheating, prior to further heat absorption from the slag layer.     

Thermochemical processing of copper-molybdenum concentrates

Results are presented from a study of thermochemical processing of copper-molybdenum concentrates by liquation smelting, which concentrates the rock-forming and ore components selectively in immiscible liquid phases. Optimal conditions for liquation smelting have been determined, under which the extraction of molybdenum amounts to 80%, copper and bismuth 95% and 100%, respectively. Buryat Institute of Natural Sciences, Siberian Branch, Russian Academy of Sciences, Ulan-Ude. Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 1, pp. 101–103, January–February, 1999.