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By Xinghai Lei, Yuqi Shang, Guiming Li, Lu He

There are many factors affecting the stability of open-pit mine slopes, among which slopes with soft interlayers have become an important factor inducing deformation and instability due to their poor mechanical properties. In this paper, for the destabilization of a slope with soft interlayer under rainfall infiltration in an open-pit mine in Zhejiang Province of China during the rainy season, a sudden change of displacement at the monitoring point and the formation of a continuous plastic deformation of the slope are proposed as the criteria for slope destabilization through the establishment of a rainwater seepage-stress coupling model combined with the strength reduction method, and by using COMSOL Multiphysics finite element numerical simulation software to establish a three-dimensional numerical model based on the actual mining slope conditions. The safety principle is introduced through the strength reduction method to analyze the stability of the slope with soft interlayer under the coupling effect of seepage and stress. The safety coefficients of the slope with soft interlayer are calculated by using Numerical methods under the coupling effect of seepage and stress. The influence of rainfall intensity and duration on the stability or safety factor of the slope with soft interlayers was studied through analysis of stress, saturation, displacement, and pore pressure evolution. The mechanism of rainfall affecting slope stability was investigated, and the findings were validated using an engineering case study of a slope with a soft interlayer. The findings show that rainfall intensity is the main factor affecting slope stability in the open-pit mine slope with soft interlayer. The higher the rainfall intensity, the faster the shallow soil forms a saturation zone, whereas soft interlayers speed up the process and endanger slope stability. The slope prevention and control technology of the prestressed anchor cable (rod) framework was proposed based on the slope management construction conditions of the mine, and the effectiveness of the measure was verified through on-site industrial tests. The research findings provide a reference for preventing and controlling slope with soft interlayers in open-pit mines under similar conditions.

Feb 20, 2024

By Philemon Desrochers, Ken Qian Liu

Following the success of the West Ore Zone distress mass blast in 2001 at Brunswick Mine, a similar approach was taken to distress the North Regional Pillar (NRP) which contained over 3 million tonnes of high grade ore. The NRP is located on the 1000 m Level with very poor hanging-wall (H/W) rock mass qualities. After an extensive geotechnical review, the distress slot is located close to the foot-wall (F/W) of the NRP in order to have the competent ore as H/W. The longitudinal area to distress covers 115 m along the strike and 85 m high from 1000 1-sub to 850 Sill. Prior to the final mass blast, 3 voids were created to allow rock swelling: the North void, the South void and the trench just below the mass blast. After over one year of preparation, the mass blast of 202,000 tonnes was successfully initiated on February 7, 2003 with 1561 electronic detonators and 210,000 kg of emulsion explosives. The blast achieved its objective of distressing the NRP as indicated the mine-wide micro-seismic monitoring system. This paper describes different stages of the project from void preparation to the mass blast itself, as well as some detailed aspects such as muck-pile prediction for mucking sequence with the help of DMC_Blast simulation code and electronic detonators.

Jan 1, 2004

By M. Drozd, A. Ibrado, P. Butcher

While effective in treating refractory sulfide ores, pressure oxidation leaves carbonaceous matter unscathed and able to adsorb gold from cyanide solutions. Barrick Goldstrike's strategy to mitigate this problem is to minimize contact between dissolved gold and native carbon in advance of the carbon-in-leach (CIL) process. Measures currently in use include limiting carbonaceous matter in the plant feed by meticulous blending of ore, controlling the degree of oxidation in the autoclaves and blinding native carbon surfaces with lauryl sulfate. The presence of residual cyanide and thiocyanate in the process water remains to be a cause of premature gold dissolution and loss of gold by adsorption on carbonaceous matter. This cyanide is introduced by water that is recycled from the tailing pond. Of several treatment options considered, oxidation by peroxymonosulfuric acid, also known as Caro's acid, is deemed to be the most effective. Laboratory and pilot plant tests show that Caro's acid can oxidize free cyanide, weak¬acid-dissociable (WAD) cyanide and thiocyanate, resulting in significant improvements in gold recovery downstream. The process requires Caro's acid at 125 % of the stoichiometric requirement and pH in the range of 9.5 to 10 to accomplish the desired destruction in about twenty minutes. A cyanide destruction plant is currently being designed and construction should be completed by the end of 2005.

Jan 1, 2005

Beatrix Gold Mine, a deep-level gold mine in the Free State province of South Africa, has the highest methane emission rate of any gold mine in the country. Methane is emitted from underground sources intersected during mining operations and is liberated into the general mine atmosphere. The total methane emission rate for the mine is of the order of 16001/s and the South section of the mine emits approximately 10001/s of methane gas. The mine has a history of gas accumulations which have led to a number of underground explosions. Following the last explosion in 2001 and the subsequent investigation, a number of recommendations were made. Two of these were to consider extracting the underground mine methane to render the mine atmosphere safe, and to declare hazardous locations that require special operating procedures. A number of such workplaces have now been declared at the South section of the mine. Methane gas is a potent, explosive greenhouse gas whose contribution to global warming and climate change is 21 times higher than that of carbon dioxide. To reduce its inherent danger and to mitigate its global warming impact, a carbon credit project under the Clean Development Mechanism (CDM) of the Kyoto Protocol has been developed and implemented, the aim being to capture and destroy the methane at Beatrix mine. The mine has constructed an extraction system to capture and extract 400 (Is of the methane. Percentage methane (per volume) of the gas intersected at source is 85%, with negligible concentrations of other hydrocarbons and water associated. The mine contracted the services of Group Five to design and construct the flare and ancillary equipment on surface, and Promethium Carbon was contracted to assist with the carbon¬-related aspects, approval framework, and administration of the project. A number of design and construction challenges had to be faced to extract and transport the gas effectively to the surface of the mine as the emitters are approximately 3 600 m away from the mine shaft at a depth of 860 m. Further considerations were the requirements for the type of column to be used to transport the methane gas, the pressure loss over the system, the safety systems needed to address the risk factors involved in the transport of the methane gas, and a suitable pumping system to extract the gas to the surface. The system operates under negative pressure provided by two blowers on surface delivering the emissions to a flare capable of burning off 450 8/s of methane gas. In this paper a number of benefits for the mine are discussed. These include, but are not limited to, the removal of approximately 55% of the total volume of methane gas from the general body of the air in the geographical areas of the mine where the methane gas is emitted into the atmosphere, and reducing the risk of methane-related incidents. A further benefit of this project is the mitigation of the global warming impact of the methane gas and the reduction of the mine's carbon footprint by approximately 25%. This project could also assist in alleviating the energy shortage being experienced in South Africa by means of the planned generation of 4 MW of electrical power, utilizing the methane gas, as a second phase of the project.

Jan 1, 2011

By J. R. Dawson, A. B. Kinzel

THE purpose of testing is to determine whether the material in question is identical in all essential respects with similar material which has given satisfactory service. The most common method of securing such information is to select samples as representative of the entire material and subject them to destructive tests. As the welding industry grew, service data were accumulated and tests of welds took on new significance. New tests were devised and old tests modified so as to be more pertinent to welding. Moreover, in some cases the generally accepted procedure of testing by sampling is not accorded the same degree of confidence when applied to welds as in the usual applications. Thus, in instances where great hazard would be involved should the material fail, means of non-destructive testing have been sought with favorable results. Accordingly, tests used today may be divided into two groups, destructive and non-destructive tests.

Jan 1, 1930

By Richard A. Heckman

Destructive Thermal Technology (DTT) is used in the management of various waste streams. DTT includes Destructive Distillation, Pyrolysis and Classical Incineration. Recent work has more clearly defined the differences in these technologies based upon a more rigorous thermochemical approach. The U.S. Environmental Protection Agency (EPA) has chosen Classical Incineration as the Best Developed Available Technology (BDAT) for the management of hazardous organic wastes. Municipal Solid Wastes (MSW) and Sewage Sludges (SS) are also managed using Classical Incineration. Three environmental problems plague the use of Classical Incineration. Destructive Distillation, on the other hand, avoids these problems. It is an environmentally benign DTT for managing a wide variety of organic waste streams, including hazardous wastes. Thermochemical analysis of the available data on the performance of three types of DTT will be discussed.

Jan 1, 1994

By Ho-Sang Sohn

The kinetic study on desulfurization of copper matte by gas bubbling was designed under the presumptions of lower FeO activity and of no slag formation, Copper matte with 59% Cu and 22.6% S in weight was oxidized at 1523K by bubbling of Ar + O2 gas through a submerged nozzle. The effects of oxygen partial pressure and flow rate of gas on the oxidation rate of matte were discussed. The desulfurization rate and the evolution rate of SO2 gas of copper matte were significantly influenced by the oxygen partial pressure, but the dependence on gas flow rate was rather complicated. The desulfurization rate and evolution rate of SO2 gas of copper matte were described by the mass transfer rate through the gas film around the rising gas bubbles. Thermodynamic correlation equations between the partial pressure of gaseous species and matte composition were incorporated to the kinetic calculation, The present model shows that the reaction path starts to transiently cross over an isobar line of PSO2 to asymptotically approach to the particular isobar line drawn in a matte composition plane of %S and %O.

Jan 1, 2003

By M. H. Erten

Most of the fourteen workable coal seams in the State of Missouri have high ash and sulfur levels and need beneficiation in order to meet customer and Environmental Protection Agency requirements. If proper ash and sulfur removal methods can be designed, more Missouri coals will be mined and used within the state. One of the main objectives of this research is to investigate the possibility of removal of sulfur of Missouri coals by conventional beneficiation methods.

Jan 1, 1982

By Valery Kaplan

Sulfur emission in the form of SO2 in flue gases is one of the most serious atmospheric pollutants associated with coal combustion and non-ferrous metals production. The carbonate eutectic method for removing SO2 from flue gases at 723–923 K was initially proposed in the 1970s but despite its great efficiency (SO2 concentration in the flue gas after purification reached 0.003 volume %), it could not be implemented by industry due to the complexity of the carbonate melt regeneration stage. Earlier we proposed a method suited to coal-firing power stations where the melt was regenerated using CO as a reducing agent. However, most metallurgical plants do not use coal and therefore lack a large source of CO. Here we propose a method for removing sulfur from the carbonate eutectic melt by purging it with natural gas or a natural gas/air mixture, which are available in the vast majority of metallurgical plants. This reaction leads to the reduction of sulfate to H2S gas that leaves the melt. The experiments we conducted show that nearly complete sulfur removal from the melt is possible at 823 K and that the reaction rate is sufficiently high for a large scale process. One can foresee that this carbonate melt-based SO2 removal technique may become a practical and economically attractive method for limiting sulfur emission to the atmosphere from non-ferrous metallurgical processing plants.

By George S. Evans

CERTAIN American operators believe that desulphurizing in the ladle offers a means of increasing blast-furnace and open-hearth yields with the possibility of improvements in quality of the steel. In fact, several producers have experimented with practically all of the known desulphurizing agents, including both standard grades of the alkalies and special preparations that have been offered from time to time during the past several years. Some of these are regularly being used today in large-scale commercial operations, with good results. Also, it is the practice to treat off-sulphur casts in the blast-furnace ladle at a number of plants. It is not known, however, that anyone in the steel industry (American) has ever adequately equipped a plant for desulphurizing blast-furnace metal in an efficient manner as regular operating practice. The purpose of this paper is to illustrate the importance of correct equipment and proper handling for obtaining uniform and efficient results. As will be shown, at the temperature of molten iron the alkalies are instantly neutralized by any free slag present, dissipating their desulphurizing value. Entrained silicates are rapidly washed out of the metal bath by the highly basic soda slags and will be satisfied ahead of desulphurizing reactions with FeS. More or less of the reagent will always be used up through reactions with the refractory lining. Desulphurization will be limited to the action of the free alkali then remaining in the slag. Causes for the erratic results generally found with desulphurizing tests in blast-furnace transfer ladles would include, among other things, variations in the quantity of furnace slag coming down with the metal, and differences in the percentage of kish and entrained silicates in the different casts. As the alkalies instantly unite with any free slags or silicates present, these, with any kish coming off, both dilute the reagent and reduce the surface contact between the slag and metal, thereby retarding the desulphurizing reactions.

Jan 1, 1938

By László I. Kiss, Verena Mackowiak, Alexandre Perron, Dominic Toulouse, Alicia Liedtke, Sándor Poncsák

"Bubbles play a very important role in different metallurgical applications like for example in electrowinning. During heterogeneous nucleation, the maximal size of the bubbles growing at the nucleation sites as well as the nucleation frequency is determined by the so-called detachment condition. Detachment occurs when the external forces acting on the bubble exceed the retaining forces along the solid-gas-liquid triple interface line. The phenomenon depends strongly on the shape and orientation of the solid surface and on the nature and strength of the external buoyancy and drag forces. In the present study the detachment conditions of bubbles from downward facing horizontal and inclined plates were studied experimentally under the effect of gravitational and hydrodynamic forces. The results show the deformation of the bubbles under the effect of the external forces and the detachment conditions as function of the bubble volume.IntroductionIn heterogeneous nucleation bubbles are generated at the so-called nucleation sites along the solid-liquid interfaces. They continue to grow there and after they reached a certain size they detach from the solid surface and leave the nucleation site. This scenario is well known both in boiling and electrolysis. During the growth period a stable equilibrium exists between the forces that retain the bubble at the nucleation site and the forces that try to remove it. This equilibrium evolves with the increasing volume of the bubble to the point when the detachment forces overcome the retaining forces.The life of a single bubble generated by heterogeneous nucleation can be divided into two periods separated by the detachment - or in other words by the departure - of the bubble: first the growth at the nucleation site and then the movement away. The knowledge of the detachment conditions makes possible the determination of the maximal volume of the bubble at the nucleation site that, in tum, makes possible the determination of the nucleation frequency. This is why so many researches have been directed toward the clarification of the details of the bubble detachment in the past decades. The equilibrium between the attaching and separating forces depend on the presence of body, surface and flow induced forces in the liquid, on the geometry and orientation of solid surface, on the properties of the solid-liquidgas system etc."

Jan 1, 2004

By Narasimha Mangadoddy, Teja Reddy Vakamalla

"Vertical hydrocyclones are very common in most of the comminution circuits. Inclined cyclones are also found for specific mineral processing applications. In this work, Computational Fluid Dynamics (CFD) technique and experiments are used to find the reasons behind the inclinations effect on hydrocyclone performance characteristics. The water and silica slurry experiments are conducted with 75 mm hydrocyclone at different inclined positions (0-600) to the vertical plane. Corresponding two-phase numerical simulations are performed with Volume of Fluid (VOF) model coupled with Large Eddy Simulation (LES) turbulence model. Multiphase simulations are carried out with Algebraic Slip Mixture model modified with lift, drag forces and Newtonian rheology model corrected with fines for various feed solids concentration. A raise in the under flow solids percentage, cut diameter and a reduction in the water split is observed with the inclination. Electrical Resistance Tomography (ERT) and High Speed Video (HSV) data is used to cross validate the inclined cyclone’s CFD air-core and solids concentration data. Predicted efficiency curves are found in a close agreement with experiments for all the inclinations. Comparison of experimental and predicted flow data clearly follows trend with the literature. Key words: Hydrocyclone, CFD, ERT, inclination, water splitINTRODUCTIONHydrocyclones are devices used to separate or classify particles based on particle size difference in the water medium. Their usage is very wide in chemical, petroleum, mineral and bio industries due to its structural simplicity, high throughput, small volume, low cost and maintenance. Cyclone mainly consists of a cylindrical section followed by a conical section attached to a single feed inlet and two product outlets named vortex finder and spigot. It works on the principle of centrifugal sedimentation. The slurry is fed tangentially to the hydrocyclone, in which larger particles are moved towards the wall and separated by centrifugal forces to the underflow. Smaller size particles follow liquid due to drag forces to the overflow. With its simple structure, the flow behavior inside the hydrocyclone is quite complex. Vertical cyclones are common in practice in most of the comminution circuits. Horizontal cyclones can be found in extreme cases which are for installation convenience rather than for process reasons. Inclined cyclones are also present for specific mineral processing applications. In coal preparation plants, dense medium cyclones are operated near to horizontal inclination of 20 degrees to allow large spigot sizes for sinks removal, self-drain of contents during shutdown. In the phosphate removal, dense medium cyclones are inclined with an angle between 0-90 degrees for better separation of ore and tailings (Liu Feng et al., 2006). Even in the clusters, hydrocyclones are mounted with an inclination around the feed distributor for uniform distribution of slurry and under flow collection. It is believed in mineral processing industry that inclined cyclones would fetch the benefit in number of ways while classifying the material by size. Gravity influences the cyclone performance through the air core size and position variations in large cyclones. It also favours the cyclone operation at coarser cut points without varying any other design and operating parameters. Minimizing fines misplacement to underflow can be achieved with inclination."

Jan 1, 2016

By Adam Powell

A Cahn-Hilliard phase field model is formulated to describe transport-limited electrochemical reactions coupled with fluid flow in a metal reduction cell. When the reaction is limited by mass transfer of metal ions from the electrolyte to the cathode, the metal-electrolyte interface at the cathode exhibits a Mullins-Sekerka instability, leading to the growth of dendrite-like "streamers" of liquid metal into the electrolyte, which in turn significantly enhance the apparent mass transfer coefficient there. Model results for iron reduction from ferrous oxide in slag show formation of these streamers. Although the double-layer is not included in this model, the related phenomenon of electrocapillarity can be represented by a gradient penalty term which includes the electric potential gradient, such that interfacial energy is a function of the electric field normal to the interface.

Jan 1, 2003

By I Mason, G Turner, J Hargreaves

One of the key objectives in production from any mine is the minimisation of ore loss and dilution. This can only be achieved when the distribution of ore within the mine is known. The distribution of ore is usually evaluated from a combination of drill hole information and underground mapping data. Three-dimensional models of the ore distribution are then constructed by interpolating grades, contact locations and confirming these estimates through mapping. While the interpolation procedure can incorporate an understanding of the local geological conditions, it is an approximation and thus susceptible to some degree of ore loss or dilution. Naturally, such problems increase in areas of sparse geologic information or greater geologic complexity. Borehole radar offers an approach to decrease the interpolative aspects of modelling by providing a continuous image of some ore contacts. Borehole radar works by building a two-dimensional image of an ore contact from radio waves bounced off the contact from closely spaced positions along a borehole. This image can be imported into Datamine (or a similar design package) and incorporated into geological models of a given ore block. The results of a trial survey from the Mariners nickel mine at Kambalda are presented to illustrate the improved level of detail and accuracy that can be achieved through the incorporation of borehole radar into orebody delineation practice. Once implemented on a large-scale this technique has the potential to greatly increase the cost-effectiveness of long hole stoping at Kambalda, through increased ore recovery and reduced dilution.

Jan 1, 2000

By Khaled Morsy

In the past two decades, high horizontal stress has been attributed to many ground control failures. Most believe that entries parallel to the high horizontal stress is most stable and least stable when perpendicular to it. Entry stability decreases when the angle between entry and horizontal stress increases. The concept of 2-D stress shadow has been proposed for selection of proper panel orientation, often with mixed results. In this paper 3-D finite element modeling was used to analyze the stress distribution at the headgate of a longwall panel subject to high horizontal stress at various angles. It was found that the directions of induced principal stresses at the longwall face and headgate are independent of the panel orientation. The induced principal stresses concentrate or relief at headgate based on the panel orientation with respect to the directions of the induced principal stresses. Accordingly, only 3-D modeling can fully account for the effects of high horizontal stress on panel orientation. The paper illustrates in details the changes in orientation and magnitude of all three principal stresses around the longwall face and T-junction area as panel orientation changes.

Jan 1, 2006

By Carl E. Williams

During the past two years a computer program called "COPOR," Computerized Open Pit Optimization Routine, has been developed and used for mine planning of several base metal deposits. This routine utilizes a three dimensional computerized block model of an orebody, some economic parameters and operating constraints to locate the mineable or economic limits of the deposit schedule the yearly production from the mine and produce bench by bench ore reserve summaries and maps of the yearly and ultimate pit configurations. The moving cone method is used to perform these functions with a conventional block model. This model is conventional in the sense that each block is assumed to be homogenous; i.e., either ore or waste but not a mixture of the two. Due to the nature of a seam type deposit this approach is not realistic; therefore, revisions have been made to form a new version of the COPOR program. This version has been named "COALOR," Coal Optimization Routine. COALOR contains all of the power of the COPOR program but is equipped to handle the intricacies of coal seam type deposits. The deposit can be composed of a single seam or multiple seams which are horizontal or dipping at any angle. The numerous coal quality values can be incorporated to aid the optimization of the economic pit limits and yearly scheduling.

Jan 1, 1978

By H. Wotruba, K. Neubert

Dual-energy X-ray transmission (DE-XRT) imaging is known from safety luggage inspections at airports. The use of DE-XRT technology for sorting applications in the primary raw materials industry has been the subject of numerous investigations. Beside other metal ores, X-ray transmission sorting is already used for the preconcentration of tungsten ore, gold ore and coal. The applicability of DE-XRT sorting is limited to ore types where differences in metal concentrations are measurable, based on an interpretation of X-ray images. Metal contents in particles occur in large varieties in terms of concentration, grain sizes, spatial distribution and mineralogy and therefore influence the X-ray absorption. As a result, each ore has to be tested individually for its suitability for DE-XRT sorting. The objective of current research at the Department of Mineral Processing (AMR) at RWTH Aachen University is to assess parameters influencing the detectability of rare earth oxides. Two approaches were followed: (1) Practical test work, based on artificial ore samples of defined compositions and (2) Computer-based simulation of absorption features of identical particle compositions. In total, more than 300 artificial samples of various compositions and metal grades were produced and X-ray images from DE-XRT sorting were analyzed. Results from the DE-XRT sensor were put into correlation with metal grades and particle sizes, to analyze influences and limits on the detectability of rare earth oxides. In addition, a new approach was tested in which the X-ray absorption of particles of various compositions was determined based on a Monte Carlo (MCNP) simulation. During the simulation, similar compositions, as used for the artificial samples, were tested and the X-ray absorption behavior during DE-XRT sorting was determined. A comparison of results from both approaches is used to assess the applicability of the MCNP-simulation for the prediction of the X-ray attenuation behavior during DE-XRT sorting.

Jan 1, 2016

By L Lachance, F Flament, D Leroux, S Gariépy

The pervasiveness of poor sampling practices in and around mineral processing plants could seem intriguing in view of the various documented evidences both for causes and consequences. To this extent, this paper revisits the well-documented but lesser-known fact that failure to care sufficiently about how samples are selected and managed is the mother source of almost all sampling biases. The authors believe that the potentially huge leverage between causes and consequences as well as the diversity of people involved in sampling call for a globally integrated solution rather than for a point solution. Such a globally integrated solution has already been put forward by the AMIRA P754 Metal accounting – code of practice and guidelines (AMIRA, 2007) that inherently requires accuracy to be targeted, measured, reported and managed. Furthermore, always in order to avoid a point solution, several layers of protection against biases must be put in place with each one involving a different ownership whenever possible. This is exactly the role intended by the supervisory bias detection method described in this publication. It is based on the continuous monitoring of the expected value of reduced residuals obtained from statistical data reconciliation conducted in a metal accounting context. This supervisory bias detection method is developed in full details after which Monte Carlo simulations are done on a mineral processing plant example for showing how it can be successfully applied for detecting hidden biases.CITATION:Lachance, L, Leroux, D, Gariépy, S and Flament, F, 2014. Detecting sampling biases in metal accounting, in Proceedings Sampling 2014 , pp 109–120 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 29, 2014

By K. Raht

LEAD poisoning is perhaps the oldest and, until recent years, the most misunderstood of all industrial diseases. Hippocrates appears to have recognized a relationship in the colic experienced by a patient who worked with metals, and the ancient literature is filled with references to the colics and 'dry bellyaches'. The colic and other sequalæ following drinking of lead-bearing waters and, particularly, wines has excited possibly more comment in the older medical literature than any other ætological factor. It was not until1656, when Stockhusen definitely connected the colic of the workmen with the fumes given off in the process, that the true danger to those working with lead was recognized. Unfortunately, something over 200 years elapsed before industry took any note of Stockhusen's discovery; it remained for Legge and Goodly and investigators of the early 1900's to forcibly educate their profession and industry to the manner in which lead gained entrance to the body. The work of Legge and Goodly was published in 1912 and the clearness with which these investigators presented the scientific data which they had accumulated will mark this volume as perhaps the first and most important contribution to our modern knowledge of the subject. It also ushered in a period when, in the short space of thirty years, lead poisoning has been reduced from one of the most baffiing and widespread o industrial diseases to one which can be anticipated and controlled. The next great contribution came in 1926 with the publication of the work of the Harvard group. Here, for the first time, was the physiological behaviour of lead laid bare, and it is to the discoveries of these authors that we owe our modern treatment of lead poisoning.

Jan 1, 1941

By Stephen L. Chryssoulis

The detection and quantification of invisible gold by microbeam techniques is discussed. Ion probe microanalysis is used to quantify the gold content of individual sulphide, sulpharsenide and oxide particles with a detection limit of 0.2 ppmw (g/t). The proton microprobe is used to determine the gold concentration of gangue minerals with a detection limit of 2 - 4 ppm. Using these techniques complete mineralogical balances for gold are obtained to assist in the process selection and optimization. A total of twenty gold and gold-bearing ores have been examined. Selected examples are presented.

Jan 1, 1990