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By L. Xia, B. Hart, J. Nigim, Z. Chen

"Grinding ore is an important step in the flotation process. Not only does grinding reduce particle size and liberate minerals, it also creates conditions for reactions to occur on particle surfaces that can aide or inhibit flotation. There have been numerous studies examining various grinding regiments and the effect on flotation pulp chemistry, including autogenous grinding and using media of variable composition. There have been however, few studies looking at the effect of variability in grinding media size on pulp chemistry and subsequent flotation. This study attempts to link changes in pulp chemistry in response to variations in grinding media size to flotation recovery. It uses probes mounted in the grinding chamber (pH, Eh, DO, and conductivity) to monitor pulp chemistry changes during grinding of a Cu-Zn ore. Surface chemistry analysis by ToF-SIMS was performed on sphalerite from the mill discharge. Activator and depressant species were monitored on the mineral surfaces and their presence was evaluated in the context of variability in pulp chemistry linked to differences in grinding media and its ball size.INTRODUCTIONIt has been widely recognised that not only does grinding reduce particle size and liberate minerals but the grinding environment has a large effect on the flotation of sulphide minerals. This effect is attributed to Eh change, iron hydroxide coating on surfaces, oxygen reduction, precipitation from solution and galvanic coupling (Grano, 2009). As early as 1960, it was reported that after grinding the ores in an iron mill the natural floatability of sphalerite was reduced significantly (Rey and Formanek, 1960). Kocabag and Smith (1985) studied on the industrial circuits showing that the depression of sulphides flotation in a steel mill is possibly due to the coating of iron oxidation products. Peng, Grano, Fornasiero, and Ralston (2003a, 2003b) found that iron contamination from grinding media plays a dominant role in depressing galena and chalcopyrite flotation. Huang, Grano, and Skinner (2006) reported the same observation in the flotation of arsenopyrite."

Jan 1, 2016

By Sergio Romo, Gerardo Fuentes, Adriana Garcés

Refractory ores with gold entrapped in a sulfide matrix, must be processed in a first stage with chemical or physical treatment in order to liberate the gold for a subsequent step with cyanide. The goal of this research was to compare the refractory behavior of a gold concentrate treated using two pretreatment methods: pressure oxidation and fine grinding. Gold concentrate from Viacha Mining in Bolivia, assaying 50.11 gpt, with a P80 of 131 ?m was used. The concentrate contains arsenopyrite and pyrite as main sulphides in the matrix. A preliminary test with cyanide resulted only 13.5% of gold extraction with 4 hours of stirred leaching. Using an autoclave oxidation with sulphuric acid and 12 bar oxygen pressure at 220°C pretreatment, the cyanide gold extraction increased to 69.0% in 4 hours. When material was ground in a pulverizer, producing a P80 of 20 ?m and the product directly cyanided, stirred leaching gave a gold extraction of 65% in 4 hours. For both techniques, the effect of temperature, sulfur produced in autoclave oxidation, optimization of the cyanide and the nature of residues were also studied.

Jan 1, 2014

By J. Drenda

The model for methane removal from the workings directly behind an advancing longwall as presented in this paper may be used for U-ventilated cross or length-wise systems of longwall advance, starting from the boundaries of the extraction field. In mines with high methane concentrations, Uventilated longwall extraction from the boundary of the extraction field produces a methane risk. The risk is manifested by a higher methane concentration at the end of the longwall, upper gate and incline. The methane in increasing concentrations, which is emitted mainly from the workings with caved areas, appears towards the end of the longwall and in the upper gate. The graphical model of the longwall provided includes both the workspace of the longwall and the caved area. Based upon a model of the rock distribution in the cave, a ventilation model comprising two standard air splits and large number of crosswise air splits has been constructed. Simulations indicate that if the shearer is not present in the longwall, the air distribution in the caved area is symmetrical. The presence of the shearer, both at the bottom and the top of the longwall, causes an asymmetrical air distribution in the cave, that is the asymmetrical flows in the goaf and longwall workspace and in the inflows and outflow between those regions. This phenomenon causes an increase in methane concentration at the end of the wall and at the upper gate. The methane removal method proposed for workings with a caved area directly behind the advancing U-ventilated longwall, starting from the boundary of the field, consists of the removal of methane-air mixtures from the caved area with the boom pipes. These booms may be of several meters long and may be extended if necessary. The insertion of the boom pipes into the cave towards the end of the longwall and connecting them with the general methane removal system creates negative pressure causing a change in the depression field, which is the aerodynamic potential field in the goaf area around the ends of the boom pipes. This will promote the extraction of the methane-air mixture from voids and the goaf cracks, and the area from which methane is being extracted may extend to the side of the cave. This is a positive phenomenon, which could result in the methane flow from the goaf into the airflow in the longwall workspace decreasing or even stopping. A reduction in the methane flow into the longwall workspace with extractions booms will be advantageous for the production continuity. Based on the floor load model for the rocks in the cave and the methane-removal boom load model, the value of the force required to move the boom behind the advancing wall has been calculated. Strength calculations for the pipe were performed using a finite elements method. The analysis results, as well as the comparison of the pipe material effort to the strength parameters of steel, which can serve as piping material (for the assumed load conditions), lead to a belief that the proposed boom construction satisfies the strength requirements.

Aug 1, 2013

By P. J. Finnis

This paper describes the use of wire rope on open-pit mining equipment, giving specifications and examples of the performance achieved. Installation methods are also discussed, making the paper of considerable practical use to mine operators.

Jan 1, 1973

By J. Duriez, L. Scholtès, F. V. Donzé

"Fracture propagation process in brittle rock is investigated by means of numerical simulations performed with an adapted formulation of the discrete element method. The progressive failure mechanism is simulated through the breaking of the bonds making up the cohesion between the elements constituting the simulated medium. The use of appropriate contact laws associated to a near neighbor interaction feature provide the model the ability to reproduce fundamental characteristics of brittle rock behavior such as, for example, high values of the tensile to compressive strength ratio. Great attention is given to accurately describe the properties of the pre-existing joints or faults in the model. A specific joint model gives the possibility to define a tailor-made behavior of the discontinuity surfaces without suffering from discretization bias.Compression test simulations are performed on pre-flawed samples and compared to experimental results in order to validate the numerical approach for describing the initiation and propagation of fractures in brittle rock under mode I+II loading. It is shown that the crack mechanical parameters can greatly influence the fracturing pattern, in particular its frictional properties. Overall, the numerical simulations reproduce fairly well the failure patterns that are obtained experimentally.The discrete model is then used to study mode I+III loading to give an insight into fracturing problems occurring at the scale of the continental crust. The ability of the model to support mechanically the physical modelings performed with wet clay or sandbox is shown. As an example, the model is used to track the development of a twist crack system (wrench fault) through the nucleation and coalescence of microcracks."

Jan 1, 2015

By M. Mirnezami, J. A. Finch, M. S. Hashemi A.

The surface of -30µm silica suspension (2% v/v) treated with 100 ppm Mg2+ at pH 11 was fully coated with Mg(OH)2. Under this condition, the silica is strongly positively charged (+30 mV) and the suspension is dispersed. Subsequent addition of Ca2+ promoted aggregation and reduced the surface charge. At this pH calcium is present as Ca2+ and CaOH+, i.e., positively charged ions interacted with the positive surface. Aggregation by a chemical bridging mechanism is proposed. The observation may be relevant to the widespread practice in mineral processing of adding lime to promote aggregation and settling in concentrate thickeners.

Jan 1, 2004

By M. P. Rennick, D. M. Burton

Abstract -The Murray Brook massive sulfide deposit, which was the first geochemical discovery in the Bathurst camp, is one of the largest sulfide deposits in the area. The massive sulfides are hosted by quartzose metasedimentary rocks in the lower part of the Ordovician Tetagouche Group. This thick succession of sedimentary rocks is overlain conformably by felsic volcanic rocks, and is structurally overlain by mafic volcanic rocks. The massive-sulfide body is polydeformed, but primary metal zoning is still discernable and may permit future exploitation of discrete lead-zinc and copper zones. Although it was discovered in 1956, the deposit was not developed unti11989, when Murray Brook Resources commenced processing of gossan containing precious metals. Recovery of gold, silver, and mercury is accomplished by indoor vat leaching on a year-round basis.

Jan 1, 1992

By T. Gonzales, M. Maleki, M. Caçador, B. Climenhaga, H. Ghorbani

The campaign life of furnaces in the copper making industry is greatly affected by damage caused by normal operation cycling and abnormal conditions. Proper monitoring and assessment of the existing conditions and safe remaining life of the vessels and their refractory lining is key to prevent an unplanned early replacement. This paper presents an industry-proven refractory management program as well as a typical fitness-for-service assessment of a rotary vessel shell in order to extend the campaign life of copper making furnaces and enhance safety. The furnace refractory management system involves a comprehensive audit and monitoring program which has been successfully applied to several copper flash smelting furnaces over the past 15 years. The fitness for service assessment provides a methodology to estimate the remaining life of the steel components by evaluating the existing damage and future damage rate based on the historical survey data. The above practices can provide the operator with cost savings by extending the vessel campaign life in lieu of implementing more rigorous refractory lining and shell audits. INTRODUCTION Primary copper smelting is generally divided into two categories of flash smelting and open bath smelting. There are many different types of vessels that can be used to convert the copper concentrate to blister copper including, flash, Mitsubishi process, TSL (ISA/Ausmelt), SKS Bottom Blowing, Anode and Teniente/Noranda furnaces, reactors, and Peirce Smith converters. Each vessel has its own complex and intense environment which requires careful refractory and steel design to withstand the severe thermomechanical and thermochemical attacks within its campaign life. The campaign life of furnaces is greatly affected by damage caused by normal operation cycling and abnormal conditions. Proper assessment of the existing conditions and safe remaining life of the vessels and/or refractory lining is key to prevent an unplanned early replacement. This paper presents an industry-proven refractory management program as well as a fitness-for- service assessment methodology to estimate the remaining campaign life of copper making furnaces resulting in cost savings and enhanced safety of the operating vessels.

Jan 1, 2019

By R. P. van Hille, A. W. van Zyl

The BIOX® culture, aiding liberation of arsenopyrite/pyrite occluded gold, is inhibited by thiocyanate (SCN > 1 mg/L); precluding the recycling of tailings water up-stream of the bioleaching circuit. The activated sludge tailings effluent remediation (ASTERTM) process is a biological process that was developed to facilitate water recovery and treat waste water on-site (to achieve a SCN concentration < 1 mg/L) to be recycled or disposed of. The aim of this study was to investigate the effects of changing temperature and SCN loading on the SCN degradation ability of the mixed microbial population clue to seasonal temperature changes and fluctuations of SCN concentration in the waste water.

Jan 1, 2011

"Coupon testing has been used to investigate stress corrosion cracking (SCC) of rockbolts in a laboratory based experimental program. This program has focused on the use of ASTM G39 three- and four-point bent beam coupon specimens, immersed in an acidified sodium chloride test solution containing hydrogen sulfide. The specimens were loaded to a range of stresses from zero, to just above the materials yield strength. It was found that only specimens above an applied stress of 580MPa failed by means of SCC, showing that rockbolts loaded to near their yield strength may be susceptible to SCC in-situ.INTRODUCTIONStress corrosion cracking (SCC) is a failure mechanism that affects material through the growth of hairline cracks when exposed to a corrosive medium while under stress (Jones and Ricker, 1999). SCC has been found to affect rockbolts in the Australian underground coal mining industry and has the capacity to cause the catastrophic failure of ground support systems, potentially leading to falls of ground in underground excavations, injury or death to mine personnel, damage or loss of equipment, and loss of productivity through the loss of roadway access (Crosky et al, 2002).Coupon testing utilises small scale samples that are intended to be indicative of the behaviour exhibited by a material in-situ (ASTM G39). The small scale, and usually high surface area to volume ratio of coupon specimens mean that they corrode at faster rate proportional to their mass, greatly reducing testing times. The small scale of the specimens allows them to be more easily prepared and handled, loaning them to mass manufacturing techniques.A previous study conducted by Vandermaat et al (2012b) into the use of three- and four-point coupon testing in-situ in an underground coal mine failed to result in SCC of the specimens. This paper serves as a follow up laboratory investigation in order to understand why these specimens did not fail. Previous studies into the SCC in rockbolts carried out by Gamboa and Atrens (2003) determined that rockbolt steel has a critical stress threshold of approximately 90% of the material ultimate tensile strength (800-900MPa). This study will focus on this critical stress threshold as a possible explanation for the lack of failure in the in-situ specimens (Vandermaat, 2012b)."

Jan 1, 2015

By A. F. Robertson

FOR several years, the rock-burst question has been given serious consideration by the operating staff at Wright-Hargreaves mine and, as a result of observations and experiences, several different methods of mining have been developed which are now in use in various parts of the mine. These are described in the following pages. It should be emphasized, how-ever, that these methods, and the views expressed in this paper, are based solely on conditions at Wright-Hargreaves mine. Such conditions may or may not be similar to those obtaining in other mines in the Kirkland Lake area, where ore occurrences, veins, wall-rock, faulting, intrusives, etc., may be entirely different. Size and shape of ore-bodies, composition of the ore-bodies and their surrounding rocks, locations of intrusives and sedimentary rocks, and direction, dip, and strength of faults, all introduce problems that are peculiar to each individual mine. Ground failure&apos; in coal and metal mines is not at all unusual. A variety of systems of mining have been developed to delay movement of large or small blocks of ground, or, in some instances, to take advantage of the fact that ground movement, due to mining operations, is unavoidable. Ground failure may be either slow collapse or it may take place with explosive violence. It is principally with the latter condition that we are concerned in the mines of the Kirkland Lake district.

Jan 1, 1939

By M. Maeda, H. Sasaki

Dissolution characteristics of metals vary significantly when they form alloys with other elements. Because hydrometallurgical processes are essential in separation and refining of non-ferrous metals, it is important to study behaviors of alloys in aqueous solutions. The authors have studied dissolution characteristics of precious metals in acid solutions using electrochemical measurement. When precious metals are alloyed with Zn, its dissolution is promoted by an increase in surface area caused by the preferential dissolution of this metal. The electrochemical study also revealed that precious metals dissolved from some alloys at unusually negative potentials; the underpotential dissolutions are explained by activations of these metals in the dealloying.

Jan 1, 2014

Productivity and efficiency of diesel-powered underground trucks and LHDs can be enhanced through the application of a range of advanced technologies. In addition, these machines are subject to ever more stringent emissions control requirements. This paper will review how various technologies can improve usability, maintainability, and performance of LHDs, through a number of examples. The use of instrumentation and monitoring to understand the role of operator practice on mucking efficiency, as well as the use of finite-element analysis to evaluate structural design, and the use of control techniques to modify operator inputs and hence decrease power consumption, will be presented.

May 1, 2002

By Farzad Mohammadi, David Kratochvil, Patrick Littlejohn

"With more rigorous regulations being enacted in the mining industry, a need exists for cost effective and environmentally compliant technologies to remove selenium from mine impacted waters to ultra-low concentrations. Existing selenium treatment methods have high life cycle costs, introduce risks of acute fish toxicity, and produce biological waste residues that represent future liabilities. Furthermore, achieving selenium discharge limits of less than 4 ppb is a challenge for existing technologies. Selen-IX™ is a technology developed by BioteQ that selectively removes selenium from mine impacted waters to less than 1 ppb. The technology is purely physico-chemical and takes advantage of the basic principles of ion exchange and electrochemistry. Unlike conventional electrocoagulation that removes suspended solids and breaks emulsions or oxidizes heavy metals, the electrochemical process employed by Selen-IX™ relies on creating conditions where iron acts as a highly effective reducing reagent transforming selenium from a dissolved species into elemental selenium bound in a solid phase. The iron-selenium by-product of Selen-IX™ is an inorganic, non-hazardous and chemically stable solid. Due to their high iron content, the solids produced by Selen-IX™ are of interest to the steel making industry as a low cost feedstock. This offtake potential can not only reduce the life cycle cost of selenium removal by reducing disposal costs but more importantly, eliminate the risk of future environmental liabilities. In this paper, the basics of Selen-IX™ technology are presented along with results of successful piloting on streams from coal and copper-gold deposits.INTRODUCTIONVarious contaminants are released into mining wastewater during the extraction and processing of metals. One such contaminant is selenium. A naturally occurring element found in rocks and minerals, mining activities accelerate its release into the environment. Selenium in trace quantities is essential to all life forms but at higher concentrations it can be harmful, especially to aquatic life where selenium bioaccumulation can lead to reproductive deficiencies."

Jan 1, 2016

By Patrick Chabot

Ce document présente une méthode hybride de long trou favorisant une méthode de minage initiale par chambre-magasin et complétée par une méthode de minage long trou. Cette méthode a été adaptée suite à plusieurs facteurs tels qu?une géologie complexe, une rareté de mineur d?expérience et un haut taux de roulement de main d?oeuvre spécialisée. Cette méthode a permis d&apos;excellents résultats par rapport à la dilution. De plus, la récupération de pilier à haute teneur par forage long trou sera expliquée. Cette méthode permet aussi de récupérer le minerai qui est resté accroché dans les chantiers chambre-magasins. Introduction : La mine Géant Dormant est une mine filonienne d?or située à environ 80km au nord de la ville d?Amos au Québec. Elle est en opération depuis 1988 et à la fin de 2007, elle a produit près de 885 000 onces d?or à partir d?environ 2 400 000 tonnes de minerai pour une teneur moyenne d?environ 11,5g /t Au. Cette mine est la propriété d?IAMGOLD Corporation depuis l?acquisition de Cambior par cette dernière au mois de novembre 2006. Elle emploie 151 employés permanents et environ 41 entrepreneurs.

Feb 1, 2008

By J. A. Russell

"UNTIL the last few years, the collieries of the Dominion Coal Company, Limited, while highly mechanized as to the cutting and transportation of the coal, still relied on the hand-loading of coal from the seam onto face conveyors. In these circumstances it was possible to assure that no large proportion of extraneous materials would be loaded with the coal, and the product could be quite well cleaned for the market by screening and hand-picking.Within the past few years, however, the Company has introduced an intensive programme of mechanization which will result in the virtual elimination of hand-loading .of coal. It has been the experience of other producers that mechanical loading inevitably leads to a very large increase in the amount of impurities in the product. This is occasioned by the fact that, at least up to the present, all types of loading machines have relied on the coal being broken from the seam by under-cutting and shooting. In this operation, a certain amount of roof and pavement material inevitably becomes mixed with the coal and, since selective loading is impossible with a loading machine, all this foreign material is loaded out with the product."

Jan 1, 1952

By C. -M. Katsari, G. N. Anastassakis

"Copper is considered one of the most important industrial metals because of its properties (conductivity, malleability) and variety of uses. Approximately 70% of the global copper is used for various electrical applications, with a significant part of copper originating from recycling, since copper can be recycled and re-used countless times, without any loss of performance and difference in the quality of recycled copper in comparison to that from ore. Copper recycling significantly contributes to natural resources conservation, waste minimization, energy saving, and overall cost reduction. Approximately, 35% of the globally produced copper originates from recycled copper.The objective of the current work is to investigate the recovery of copper from electric wire scraps using wet shaking table as an alternative to air separation methods that prevail over the wet ones in recycling processes. The tests were carried out using feed of correspondingly high- and low-grade in copper. In the first case, the wire scraps had been subjected to shredding only, prior to tabling separation; in the later, the low-content tailing of prior air separation was used as feed ?n table separation.In regard to testing, the following factors were examined: table tilt, water flow-rate, and reciprocating speed. The results of the tests clearly denote that copper wire separation from plastic polymer is feasible, as in most cases, table separation resulted in heavy products of high purity in copper and high recovery, and tailings of very low copper grade. The results of the current work clearly denote that wet tabling can be applied efficiently for the separation of recycled copper wire from plastic, as an alternative to air separation methods, as well as for the recovery of copper from the low-grade tailings derived from air separation methods."

Jan 1, 2016

By J. Xie

In underground coal mining, the potential for an outburst of coal and gas is considered to be one of the major hazards. As such, considerable emphasis is given to understanding and preventing such events. A number of indices are used in the prediction of the outburst in a coal mine. The main indices include initial gas desorption rate, gas pressure, gas content, coal strength, gas flowrate from a borehole drilled in a coal seam, and combinations of the above. Some of these indices are considered to be inadequate, inappropriate or impractical for some coal seam conditions, such as those with soft and friable coal. The Huainan Mining Group (Huainan) in China and the Commonwealth Scientific and Industrial Research Organisation (CSIRO) in Australia have been jointly developing gas content based technologies to predict the risk of the outbursts. One of the major progressive achievements is a new method for determination of outburst gas content threshold values. The method utilizes empirical analyses, numerical modeling, and seam-specific knowledge . This paper describes the method and its application for the #11 Seam at Guqiao mine, Huainan.

Aug 1, 2013

By Hyumng Sup Choi

The role of the interfacial electrical &apos;Condition on the adsorption of col-lectors on mineral surfaces has been studied by electrophoretic mobility and adsorption measurements made on zircon. From the investigation of the electrokinetic properties of zircon, H+ and OH-are seen to act as potential determining ions, thus controlling the electrical nature of this mineral. The isoelectric point of zircon occurs at a pH of approximately 5.0, and it is evident, therefore, that the zircon surface would be positively charged below a pH of 5.0 and negatively charged above this pH. The adsorption of collectors therefore de-pends strongly on the pH of the solution; anionic collectors are adsorbed on positively charged surfaces and cationic collectors on negatively charged surfaces. This, in turn, de-fines the effective flotation condition, with respective collectors, for this mineral. The above results have been correlated with the flotation behaviour obtained by the simplified flotation test using a modified Hallimond tube.

Jan 1, 1963

By C. O. Staples, J. G. Morrow

The application of cationic flotation to the upgrading of magnetic concentrates was investigated in the laboratory by both batch and continuous test procedures. It was found that the collection of coarse gangue particles with amine, heretofore considered a serious obstacle to this particular application of cationic flotation, is greatly enhanced by a drastic reduction in what might otherwise be considered normal impeller speed. Gangue flotation is in-dependent of variations in the rate of aeration. The collector and Crother additions and the impeller speed which favour the formation of a matte froth yield optimum results.

Jan 1, 1966