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By Paul W. Shelley, Daniel J. Hodges

The mining industry is undergoing a period of rapid transformative change.  This is the result of the social and financial accountabilities that the industry is faced with because of the world’s desire to cap average temperature increase to 1.50C above pre-industrial levels (UNFCC, 2016).  To limit global warming to 1.50C, greenhouse gas emissions must peak before 2025 at the latest and decline 43% by 2030.  In hard rock mining, comminution is identified as the major energy consumer, being responsible for 40-60% of the electricity use.  It follows that comminution is the major greenhouse gas emission process of the mine.  All effort is being made to radically reduce the carbon emissions of comminution. Grinding media plays a large role in the energy consumption and carbon emission story.  In recent years industry practitioners have attempted to quantify the grinding media carbon footprint.  This paper makes a definitive contribution to that discussion.  The grinding media carbon footprint is quantified in Scope 1, 2 and 3 emission terms in the context of a grinding media supplier.  Major emission contributors, steel, natural gas and electricity are discussed in detail.  The steel industry transition is a key factor. The paper will explore the steel industry transition and its effect on grinding media manufacturing.  The carbon footprint of heritage steel process routes are analysed and compared with the process routes of the future.  Emerging steel making technologies are presented and discussed.  The future of the steel manufacturing and procurement route for grinding media is proposed. This narrative allows for a comparison between the heritage carbon footprint and the future carbon footprint of manufactured grinding media.  Of equal importance is the opportunity of reducing the grinding media carbon footprint in the field.  The paper explores possibilities of reducing the grinding media carbon footprint at the customer site.  Media in use options are presented that take account of the mineral characteristics, the mill dynamics, and the product metallurgy to optimise both carbon footprint and media performance. It is intended that this is a landmark paper in the discussion of the carbon footprint of grinding media.

May 4, 2025

By K. G. Chipman

IN 1936, the Department of Mines and Resources was formed by the amalgamation of the former Departments of Mines, Interior, Indian Affairs, and Immigration. In the amalgamation, the Geological Survey and the Topographical Survey became the major divisions of the Bureau of Geology and Topography, which is a part of the Mines and Geology Branch which, in turn, is a part of the Department of Mines and Resources. The Topographical Survey was formed by combining the former Topographical Division of the Geological Survey and the air and ground mapping sections of the former Topographical and Air Survey Bureau of the Department of the Interior. The latter organization, previous to 1933, had been known as the Topographical Surveys Branch of the Department of the Interior. The amalgamation of 1936 definitely placed on the Topographical Survey the responsibility for the original mapping required for the development of our natural resources. The war has brought upon us the situation where all work has had to be in the furtherance of the war effort. With decreased staff and limited appropriations, the mapping on those scales which are directly concerned with the natural resources has been confined to the search for oil and strategic minerals. The reconstruction period will produce a different situation, with different problems. The past is behind us and it is necessary to prepare for the future. First, we should consider briefly a few general principles in the making and using of maps, then take stock of what we have, see what the needs are, and consider how we are to meet these needs.

Jan 1, 1944

By I. H. Warren, Forward F. A

The reduction of aqueous slurries of uranyl carbonate at elevated temperature with compressed hydrogen m the presence of metal catalysts and certain organic promoters has been shown. to yield uranium dioxide. The reduction takes place in a sequence of steps. The purity and sintering properties of the dioxide make it of interest as a starting material for fuel element production. Simple control can be exercised over the surface area and oxygen/uranium ratio of the product during reduction. URANIUM dioxide for fueling atomic power reactors 1s conventionally produced as a powder by simultaneously decomposing and reducing ammonium diuranate with hydrogen in a furnace at high temperature. Fuel elements are then generally made from this powder by compacting and sintering ( 1). In order that elements approaching theoretical density may be obtained,

Jan 1, 1961

By T. Majcherczyk

Shaft lining reinforcing analysis of two shafts under construction has been presented in this study. The first shaft was driven from the surface, while the second was deepened. Mining and geological conditions have been studied with respect to the lining capacity. The improvement of shaft stability comprised two elements, i.e. reinforcement of the shaft lining capacity and improvement of the strength properties of the rock mass. In both tested cases, the particular hazard was connected with non uniform loadings of the lining, which could generate shearing stresses within lining structure. Thus such elements as armored concrete with high strength properties, bolting and injection sealing of the rock mass, and the use of special ring reinforcing the shaft lining have been used in order to reinforce the shaft-rock mass system. Practical conclusions related with new technological solutions, allowing the rock mass and shaft lining reinforcement, have been included for the present study. Practical conclusions related with new technological solutions, allowing for rock mass and shaft lining reinforcement, have been also included to the present study.

Aug 1, 2013

By F. Vasilikou

Commercial deployment of Carbon Capture Utilization and Storage (CCUS) requires field testing of a scale that can stress the geologic reservoirs. One such reservoir of interest consists of unminable coal seams that exhibit favorable characteristics and depositional environments and lower pressure and temperature than other, deeper, reservoirs. Such conditions can reduce compression costs while utilizing the action of adsorption that offers a more effective carbon dioxide (CO2) bonding than free storage or solution. To ensure the success of such tests, a number of parameters should be accurately determined, such as the seam geometry and stratigraphy, coal porosity and permeability parameters as well as optimum injection conditions. In essence the CO2 injection model should be calibrated for the reservoir characteristics using all available data. History matching calibrations are based on gas and water production from existing wells prior to injection. This paper will present reservoir models that were developed for a pilot--scale 907 tonnes (1000 tons) CO2 injection test that was performed in 2009 through one legacy coalbed methane production well in Russell County, Virginia, USA. The model incorporates a number of individual coal seams about 0.3 m (1ft) in thickness located at depths ranging from 300 to 700 m (1,000 to 2,200 feet). Model calibration was performed through history matching to prior production data, and subsequently the model was utilized to develop different injection scenarios. The developed model was used after injection to calculate CO2 plume distribution patterns that were monitored at the injection test. The paper will present model data and assumptions with a special emphasis on the effect of hydraulic fractures and the skin factor to the coalbed methane (CBM) production model.

Aug 1, 2013

By A. Taylor, E. Thorn Corthay, J. Farrell, L. A. Westfall, S. Borchardt

Mining and metallurgical industries need to minimize their greenhouse gas (GHG) emissions; Hatch specializes in conducting mining and metallurgical energy management assessments and optimizing productivity. Projects executed have demonstrated that there is a wealth of energy management, waste reduction, and process efficiency improvements that require no or low capital investment. Typical energy cost savings are on the order of 5% to 12%, with similar reductions in GHG emissions. Hatch generates Marginal Abatement Cost Curves to optimize the implementation pathway, maximizing carbon abatement and minimizing cost. The findings of a practical case study from Cameco are presented.

Jan 1, 2010

By C. G. Bruce

"ON NOVEMBER 15th, 1950, the Department of Mines and Technical Surveys announced the discovery of vermiculite near Perth, Ontario. The announcement followed nearly a month of study to determine so far as possible the potentialities of the deposit and quality of the material from surface indications. The mineral was identified by the writer in the field among samples submitted by Mr. Arthur Powers of Stanleyville or, September 22nd, 1950. Within a week of the announcement, mining rights to properties covering a major portion of the deposit had been acquired by commercial interests.Hitherto, Canada has had to import her entire requirements of vermiculite. Prospects of .a domestic supply gave promise of considerable benefit to many industries, particularly the building industry, and to the consumer public. Should the deposit •prove large enough there was also the possibility of exporting to centres in the United States.Field and laboratory studies were continued at the Mines Branch during the winter of 1950-51 as opportunity occurred. It is the purpose of this paper to describe the results of these •preliminary investigations, to attempt to present the Stanleyville occurrence in its proper perspective with regard to similar occurrences elsewhere, and to review the salient features of the vermiculite industry.Properties and UsesVermiculite is a hydrated magnesium aluminum silicate. In appearance it resembles mica, having the same micaceous cleavage, but it differs from that mineral in being very soft, pliable, and inelastic. Colours range from black through dark olive-green and brown to almost colourless."

Jan 1, 1952

By C. Díaz, M. Barati

Prof. Torstein Utigard's untimely death, in the spring of 2012, put an abrupt end to a meritorious career in the field of high temperature chemical process metallurgy. As an academic in the Department of Materials Science and Engineering of the University of Toronto, Torstein made solid contributions to the advancement of knowledge pertaining to production and refining of both nonferrous and light metals, and to the development of inquisitive and innovative young people in extractive metallurgy. In this profile, the authors highlight aspects of Torstein's rich personality and of his contributions to his field of expertise.

Jan 1, 2015

By Andrea Lisjak Bradley

Clay shales are currently being assessed as possible host rock formations for the deep geological disposal of radioactive waste. However, one main concern is that the favourable long-term isolation properties of the intact rock mass could be negatively affected by the formation of an excavation damaged zone (EDZ) around the underground openings. The goal of this thesis was to develop and validate a mechanically-based model of the deformation and failure process of a clay shale, namely Opalinus Clay (OPA), with particular focus on the influence of anisotropy on the short-term response of circular tunnels. To achieve this goal, a hybrid continuum-discontinuum numerical approach was developed in combination with new field measurements from the Mont Terri underground research laboratory. The response of OPA during the excavation of a full-scale emplacement (FE) test tunnel was characterized by geodetic monitoring of wall displacements, radial extensometers and longitudinal inclinometers. The deformation measurements indicated strong directionality induced by the combined effect of in-situ stress field and bedding planes striking parallel to the tunnel axis, with the most severe deformation occurring in the direction approximately perpendicular to the material layering. Computer simulations were conducted using a newly-extended combined finite-discrete element method (FEM/DEM), a numerical technique which allows the explicit simulation of brittle fracturing and associated seismicity. The numerical experimentation firstly focused on the laboratory-scale analysis of failure processes (e.g., acoustic activity) in brittle rocks, and on the role of strength and modulus anisotropy in the failure behaviour of OPA in tension and compression. The fracturing behaviour of unsupported circular excavations in laminated rock masses was then analyzed under different in-situ stress conditions. Lastly, the proposed modelling methodology was applied to the aforementioned FE tunnel to obtain unique insights into the EDZ formation process around emplacement tunnels for nuclear waste. The calibrated numerical model suggested delamination along bedding planes and subsequent extensional fracturing as key mechanisms of the damage process potentially leading to buckling and spalling phenomena. Overall, the research findings are already having a direct impact on the preliminary design process of an underground repository for nuclear waste in Switzerland.

Jan 1, 2015

By H. M. Lewis

The current status of the international zinc market is summarized, and a supply /demand outlook is presented for the next five years. A number of technical problems facing the industry are outlined. Introduction ZINC has sometimes been called the unknown metal. Considering that on a world basis it ranks third among non-ferrous metals in production and consumption, zinc retains a certain modesty. It has no distinctive colour like copper, lacks the low density of aluminum or magnesium and is not always easy to identify as a product. The 'spangle' of galvanized steel is probably zinc's most distinguishing feature. The purpose of this article is to develop an over-all review of zinc. Starting with the current position of the metal, the major factors that will shape its future will be described so that an assessment of the outlook for zinc can be made.

Jan 1, 1978

By D. W. Duncan, A. Bruynesteyn

Acidic mine waters containing solubilized uranium have been observed in many uranium and some copper mines. In every case, the sulphide and iron oxidizing bacterium, Thiobacillus ferrooxidans, was also present. This bacterium provides the ferric iron required to oxidize u+4, both by oxidizing available ferrous iron and by oxidizing pyrite or other available sulphide minerals. This latter oxidation also provides sulphuric acid and may increase extraction by exposing more uranium. The enhancement of bacterial activity and the results of some field tests are discussed.

Jan 1, 1971

By Fabian Mohr

The methyl substituted binuclear cyclometallated gold(I) complexes [Au2(?-n-MeC6H3PPh2)2] [n = 4, 5 and 6] all undergo oxidative addition reactions with halogens and, in the case of the 4- and 5-methyl substituted analogues, with dibenzoyl peroxide to give metal-metal bonded digold(II) complexes [Au2X2(?-C6H3-n-MePPh2)2]. The 4- and 5-methyl substituted digold(II) compounds on warming or exposure to light undergo carbon-carbon coupling reactions to give gold(I) complexes containing the corresponding 2,2'-n,n'-biphenylyldiphenylphosphines. The 6- methyl substituted digold(II) complexes rapidly isomerise above ca. -20° C to binuclear heterovalent gold(I)/gold(III) compounds [XAu(?-2-Ph2PC6H3-6-Me)AuX{?2-(6-MeC6H3-2-PPh2)}], containing a fourmembered cyclometallated ring on a gold(III) centre. Surprisingly, no carbon-carbon coupling could be induced for any of the 6-methyl substituted compounds, even under forcing conditions. This difference in reactivity of the 6- methyl derivative, compared to that of the 5-methyl and unsubstituted analogues was studied by ab initio calculations using a series of model compounds. The results are in excellent agreement with the experimental findings and suggest that the key-step in the C-C coupling reaction is the partial opening of the Au(III)-P bond in one of the transition states. In the 6-methyl system this transition state is energetically inaccessible and hence no C-C coupling occurs.

Oct 1, 2003

By A. O. Dufresne

The mineral wealth of pre-Cambrian rocks in Canada has been the subject of much study by geologists and engineers (members of this Institute), particularly so in the past few years, following discoveries of mineral deposits in areas far a part. This interest is well worth sustaining knowing the numerous rich producing mines within the pre-Cambrian formations, and the vast area covered by its rocks throughout this country. The pre-Cambrian has yielded minerals, both metallic and non-metallic; of these a much diversified list could be made. In more than one district we can point to mining as being responsible for the opening up of new sections, attracting a population into regions which otherwise would have remained virgin land of little commercial value. In these pre-Cambrian formations are found the rich copper deposits of Michigan, producing without interruption since 1845, and from which seven billion pounds of copper has been won; while in Minnesota and the adjoining district, at the head of Lake Superior, are mined iron ores which have rendered possible the great steel manufacturing industry of United States, the base of the economic structure of that wealthy country. The pre-Cambrian has given Canada the nickel-copper mines of the Sudbury district, the silver deposits of Cobalt and the gold camps of Porcupine and Kirkland Lake. With all of these our members are familiar; and it suffices to mention them to bring to mind pictures of the wealth and 'the growing population, in a word the importance of mining in?those sections of the country.

Jan 1, 1926

By P. Chryssanthakis

"The aim of this study is to give a better understanding for the behaviour of the composite material RRS and the synergy effect of its components while an excavation face advances during tunneling. The lower part of the Q-system scale (i.e. Q-values of 0.4 or less for a tunnel span of 10 m) is commonly used for tunnel applications in softer rock formations. This is implied in the updated Q-chart, where the dimensioning of rock support by using Reinforced Ribs of Shotcrete (RRS) comprises the use of fiber reinforced shotcrete, S(fr), rock bolts and shotcreted beams reinforced with steel rebars. The newest part of the lower part of the Q-chart gives more information on required support compared to older Q-system versions. The RRS can be described as a three part composite material with the 3rd component being the reinforced concrete beam (with no fibers) and with steel rebars that are placed in groups and sprayed with pneumatically applied shotcrete in layers. The RRS usually have a total thickness varying between 0.20 and 0.50 m and a width between 0.25 and 0.60 m respectively. They are placed at different distances along the tunnel axis depending on the rock mass quality.In this study, an effort has been made to simulate RRS in a numerical code and to study its behaviour in a real case study. A double tube, triple lane tunnel in weathered tuff has been chosen as reference material for testing RRS under changing load. This was done by writing a FISH subroutine which is implemented in the discontinuous numerical code Universal Distinct Element Code (UDEC) that takes into account the characteristics of the reinforced beam (height, width, number of steel rebars, and spacing) in the calculation process. A rather extensive parametric study has been run by using the same key input rock mass parameters and in situ stresses (?H/?v = 0.5), and changing only the RRS key input parameters in order to simulate the changing loads during the face excavation process in tunneling. The critical part of this numerical modelling work that is under investigation in this study, is the period just after the excavation: i.e 4 hours; 16 hours after excavation; and finally after the complete curing (28 days) of the cement based components. The RRS are installed in three consecutive steps as follows: a) the application of S(fr) on the rock surface in order to even it up for the RRS application; b) radial bolting; and c) installation of the reinforcing steel rebars, that form the reinforced beam.The results show that: a) the S(fr) is almost overloaded in the first 4 hours after application in both tunnels; b) on the S(fr) and steel rebars, the stresses, axial and shear loads, as well as moments are decreasing after 16 hours and 28 days; and c) the bolts loads are increasing with time. The observed reduction in stresses and loads in both the S(fr) and reinforced beam is surprising. A possible explanation is that tunnel arches are self-supported to a lesser extent as time progresses due to redistribution of stresses in the nearby rock mass through the radial bolts. The loads in radial bolts are increasing by almost 25%. This can be seen from the overall results as we observe an increase in maximum principal stresses, displacements, shear displacements along joints and hydraulic apertures compared to tunnel baseline that has no support of any kind."

Jan 1, 2015

By D J. Murray

This paper outlines the principles of friction hoisting and the components involved, and gives a description of a specific mine hoist. Friction hoisting is compared with conventional drum hoisting, and the depth of shaft at which friction hoists become more economical than drum hoists, with respect to power consumption, is determined. Introduction T HE purpose of this paper is to outline the principles of friction hoisting, to describe the components and to show the advantages of multi-rope friction hoisting. Some calculations are made to show that the power requirements and the initial costs of friction hoists are less than those of conventional drum hoists, once a certain depth of shaft has been reached. The use of multi-rope friction hoists is gradually superseding the employment of the conventional drum hoist in many parts of the world. It results in heavier payloads from deeper levels, an increase in shaft safe-ty and a more compact installation for protection against adverse weather conditions. It was observed that where drums and friction sheaves exceeded 30 feet in diameter, a number of mechanical disadvantages were being experienced;

Jan 1, 1965

By M. Bender, H. D. Goodfellow

"Belt conveyors, because of their low capital and operating costs and inherent flexibility in handling a wide variety of products, have numerous applications in the mining industry. With the increased emphasis on improving the workplace environment, dust emissions from belt conveyors at transfer and other points have become a significant problem for many applications.The paper reviews belt conveyor dust control technology and compares dust emissions from belt conveyor systems with other possible materials handling systems. Technical information on existing belt conveyor installations which have been designed to minimize or eliminate dust emissions is summarized. The important features of good design as well as the necessary input from operating and maintenance personnel are highlighted. The status of research and development work on dust control on belt conveyor systems on a world-wide basis is discussed. A proposed methodology for field measurements of emission factors from belt conveyor systems is presented. Data collected from such a test program can be used to establish a design basis for new dust-free belt conveyors.IntroductionBelt conveyors have proven themselves over the year s in the mining industry as a reliable and low-co st method of moving bulk material at high tonnage rates. Because of the above, as well as their inherent flexibility in handling a wide variety of products, belt conveyors are often called the ""workhorses"" of bulk material handling systems. For many processing plants, belt conveyors serve as the ""vital link"" in providing feed to the plant and the removal of the finished product. As would be expected, there has been considerable engineering effort in designing rugged and reliable belt conveyor systems.It is also well known that belt conveyor systems are a primary source of respirable dust emissions. The major sources are from the tail pulley where material is received and the head pulley where material is discharged, from the return idlers, due to the fine material attached to the return belt, and from the take-up pulley. It is usually considered that for dust particles less than 10 microns, these particles will remain airborne and thus can have a profound effect on the workplace environment."

Jan 1, 1982

By T. W. Wlodek

Abstract A simplified method of fatigue testing full-dimension, as-rolled, non-machined, mining drill rods is very desirable to the mining and steel industries in the classification of steels available on the market, through the evaluation of their fatigue limits and endurance strength. In this paper one such simplified method is presented and analysed. The preliminary results show many advantages of this method, such as simplicity and constancy of loading. The type of loading applied more or less simulates the working conditions of the outside fibres of the mining drill rods. Additional advantages of this method are the possibility of testing under dry and wet conditions, its quietness, and its ease of operation. Specially designed adaptors and specially applied techniques of fixing and preparation of samples make possible the breaking of a quarter-octagon hollow drill rod in a free length of uniform section in a rotating beam machine. At first glance this seems to be difficult to achieve. In the first preliminary test three different lots of steel were used. S-N curves under dry conditions were determined. These curves permit of the classification of the drill rods on the basis of the fatigue limit and endurance strength of the outside fibres of the metal, which is dependent to a greater or lesser extent on the effect of surface decarburization, surface imperfections, and special surface treatments. The average slope of the S.N curve in the damaging zone, and the fatigue limit in equal tension-compression rotating bending, were determined for SAE 1080, chromium-molybdenum and nickel-chromium-molybdenum mining drill rods. INTRODUCTION The fatigue limit and the endurance strength of mining drill rod steels are of interest to both the mining and the steel industries. These industries are greatly interested in lowering the cost of mining by reducing the consumption of these steels per ton of ore exploited.

Jan 1, 1951

By J. Postle, Deborah McCombe

"This is the third in a series of articles about the Committee for Mineral Reserves International Reporting Standards (CRIRSCO). The first article was an interview with Niall Weatherstone, Chairman of CRIRSCO (CIM Magazine, February 2008) the second described the background and goals of CRIRSCO (CIM Magazine, March/April 2008). In 2007, CRIRSCO was adopted as the Reserves and Resources Task Force of the International Council on Mining and Metals. This decision by ICMM has resulted in an increased level of funding for CRIRSCO and the ability to advance its objectives. In mid-October 2007, CRIRSCO members met in London England to discuss the status of each of the member countries’ reporting codes and the progress of various CRIRSCO projects. Update on national reporting codes Australia: The last update of the Australian JORC Code was in 2004. While there are ongoing discussions about issues that arise from the application of the latest version of the Code, there are no plans to update JORC in the near future. Canada: The Canadian Securities Administrators revised National Instrument 43-101 in December 2005. At the same time, the Canadian Institute of Mining, Metallurgy and Petroleum published updated Resource and Reserve Definitions that are incorporated by reference in NI 43-101. CIM is continuing work on developing Best Practice Guidelines to assist practitioners in the estimation of Mineral Resources and Reserves. South Africa: The South African Mineral Reserve Committee is currently awaiting an update of the Johannesburg Stock Exchange Limited Listing Rules, which will incorporate both SAMREC and SAMVAL (South African valuation guidelines). The official launch of both codes is expected in 2008. Europe: The Pan-European Reserves Reporting Committee expects to release a consultation draft in 2008. Emphasis is being placed on industrial minerals and aggregates, which constitute a very large industry in Europe. Chile: The Chilean Certification Code was approved in early 2008. As part of the Code, a National Commission is being established to screen and review reports on a random or specific basis. United States: The Society of Mining Engineers updated the SME Reporting Guidelines in 2007. The Securities and Exchange Commission has not accepted these more up-to-date definitions and guidelines. The SME committee will continue to discuss the incorporation of these Reporting Guidelines with SEC. SME has also established a class of membership, a Registered Member, which includes disciplinary measures for non-compliance with the SME guidelines."

Jan 1, 2003

By K. Purazrang, P. Musavi Garavi, P. Sh. Naseri, P. Abachi

The fracture behavior of high strength Al7050 alloy was investigated at room and elevated temperatures using small size, V-notched tear (called Kahn specimen) and compact tension, CT, specimens, respectively.To study the elastic-plastic behavior of the alloy, the tensile test was also performed on the sub-sized cylindrical tension test specimen. The microstructure of the alloy was examined using optical- and scanning electron- microscopy. The rupture mechanisms and crack path were also studied by examination of specimens' fracture surfaces using SEM. The microstructure examination revealed equiaxed grains and some elongated grains in rolling direction, with the areas of partial re-crystallized grains where coarse intermetallic particles are mostly found.In general, fracture surfaces were indicative of dimpled ductile type. Considering the fractographs of tensile specimens, the void growth mechanism is also dominant in fracture of these specimens. Nevertheless, in some regions, smooth areas can be observed due to the friction during rupture process. The results of mechanical tests at RT made the evaluation of tear strength to 0.2 % tensile yield strength ratio, as a measure of notch toughness, available. According to elevated temperature, 150°C, test results and plots of log da/dt vs. log KI , the crack propagation behavior over discrete ranges of crack growth rates could be assumed linear and then be obeyed as a power law equation in the form of da/dt = A (KI)n .

Jan 1, 2015

By V. N. Mackiw, H. Veltman

"A process is described which permits the separate recovery of lead and zinc from complex low-grade sulphide concentrates such as are produced from the New Brunswick type of disseminated pyrite ores. This process calls for the preparation of a lead-zinc bulk concentrate from the original ore by flotation. The bulk concentrate is then oxidized under pressure in autoclaves in aqueous sulphuric acid solution, such as return electrolyte from zinc electrolysis. This yields a zinc sulphate solution and a residue containing lead sulphate, unaltered pyrite and elemental sulphur generated during the oxidation. After the oxidation, the leach slurry is briefly heated to above the melting point of elemental sulphur and then cooled. Thus, pellets containing pyrite and elemental sulphur are formed, and they are separated from the lead sulphate by screening and/or flotation. Laboratory tests have shown that about 95 per cent of the zinc and lead can be separately recovered from complex bulk concentrates. Process possibilities are discussed."

Jan 1, 1967