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By A. J. Harrison

"The introduction of an amendment to the Mines Regulation Act in the Province of British Columbia, passed in July 1974, and similar amendments since enacted by other provinces introduced the Canadian underground mining industry to the use of fire-resistant hydraulic fluids.Few, if any, of the hydraulic circuits in use in underground mining at that time were specifically designed for use with fire-resistant fluids, compared with the increasing number of such circuits conceived and in production today. The technology required in designing equipment for use with fire-resistant fluids may be likened to that associated with conventional mineral oils, but, in many respects, a variety of additional and / or alternative considerations must be taken into account. The fast-increasing use and development of fire-resistant fluids throughout all facets of industry, world wide, during the past 20 years has led to a whole new technology in system construction and component design, whereby acceptable performance can be achieved . However , the transition from conventional mineral hydraulic oils has not been without its problems, particularly when retro-fit of existing units was involved."

Jan 1, 1981

By J. M. Hollicky

The economical processing of wet and sour natural gas presents a problem due to the seasonal demand for natural gas. The plants must be sized to handle the peak loads but may only operate at half capacity on the average, in which case the sales value of sulphur and hydro-carbon liquid by-products cannot support the operating and capital costs of the plant. This must result in an increased price for the gas. This problem was solved by Pacific Petroleums and Westcoast Transmission in the design of their pipeline and plant facilities now operating in the Peace River area, where there are both wet and dry gas fields. By .building a plant to process sufficient wet gas to pro-vide the base load requirement, and by drawing on the dry gas fields for peak loads, an optimum economic operation was ?possible. The sulphur, L.P.G., and gasoline produced not only are able to support the operating and capital costs of the pro-cessing plant, but were instrumental in the sharp drop in retail prices of these commodities in the area. The sour gas and condensate is gathered from the fields in the area and transmitted in a two-phase gathering system to the gas processing plant at Taylor, B.C. The condenrnte is knocked out in inlet scrubbers. Hydrogen sulphide and carbon dioxide are removed in an amine scrubbing unit. The hydrogen sulphide is stripped from the amine and is sent to the Jefferson Lake Sulphur Company's plant which produces sulphur by the partial oxidation of the hydrogen sulphide. The natural gas, now sweet, is processed in an absorption unit to recover additional liquids, before being de-hydrated to remove water. It is then sent to Westcoast's main c8mpression station. The condensate recovered in the inlet scrubbers and the liquid re-covered in the absorption unit are fractionated to remove fuel gas, used in the plant, and to produce pro-pane, butane, and naphtha. The pro-pane and butane are scrubbed with caustic soda to remove hydrogen sulphide. The naphtha is treated with hydrogen in a unifiner unit to re-move sulphur compounds completely, and is split into a light and heavy naphtha. The heavy naphtha is .catalytically reformed to produce a high-octane blending-component. These fractions are blended with components produced from crude oil at the Dawson Creek refinery to produce a high-quality balanced gasoline with special attention being paid to volatility for ease of starting, warm up, and engine cleanliness, and octane for power and ?performance.

Jan 1, 1958

By Chen Feng

Compared to widespread successful deployment of robotic manipulators for repetitive and hazardous tasks in related industries such as manufacturing, the construction industry has achieved relatively limited benefits from robotics and soft automation. Unlike manufacturing, where robotic solutions benefit from the structured layout of the environment (e.g., factory assembly line), construction robots face unique challenges that arise from the rugged, dynamic, and unstructured environment of the work site, as well as the uncertainty and evolving sequence of occurring on-site events. This challenges any intended construction robots to not only replicate basic human motion, but also be capable of sensing and adapting to environmental changes, and making decisions based on the evolving state of the environment. Building upon recent advancements in robotic mapping, computer vision, and object recognition, the authors propose to introduce autonomous behavior at the basic task level for on-site construction robots to address these challenges in a flexible and extensible manner. This paper reports the outcome of the first phase of this research - a structured methodology for improved design and development of basic task automations - and focuses on algorithms developed for mobile robot navigation and relative pose estimation. The algorithms are implemented on a prototype mobile robotic platform, and evaluated in several experimental scenarios.

Aug 1, 2013

This paper discusses three case studies conducted at Highland Valley Copper mine (HVC) that illustrate operational improvements and insights which resulted from using the McGill University gas dispersion sensors. In the first study, the superficial gas velocity (Jg) sensor was used to implement a gas profiling control strategy for the rougher, scavenger and first cleaner cells in the Cu/Mo separation circuit. The data showed a 40% reduction of down-the-bank Cu recovery at constant Mo recovery which resulted from operating the cells at the target profiles. In the second study, the bubble size analyzer was used to better understand two mechanisms of bubble formation in the two flotation columns that make up the final Mo cleaning stage: the conventional rubber-sleeve sparger and the Microcel(TM) system. The data showed a considerable reduction of bubble size in the Microcel column which resulted in a significant increase in concentrate quality (1-2% Mo absolute) and a dramatic (4-5 fold) increase in concentrate production rate compared to the typical operation. The estimated economic benefit resulting from the improved column flotation operation was an overall 4% increase in Mo circuit recovery. In the third study, real-time measurements obtained from the gas holdup and bulk density sensors were used to infer the pulp density (% solids) in a rougher cell of the bulk flotation circuit. Validation tests demonstrated that this approach provides reliable pulp density measurements. Although promising, more work is required before implementing this approach at HVC.

Jan 1, 2009

By Michel Masse

1. A battery-powered wireless mesh network for dynamic diesel machinery tracking and operating status monitoring. 2. A real-time ventilation model and fan speed optimizer. 3. An OPC server for information interchange. 4. OPC linkage to existing control infrastructure. 5. A Human Machine Interface (HMI) providing data archiving, trending and reporting. 6. Live MS-Excel to interrogate the simulation, controls and optimizer. 7. The battery-powered network mesh also provides SCADA functionality to route optimized setpointsto the fans and automated regulators not linked to PLCs.

Feb 1, 2008

By G. W. Harris, P. Mousset-Jones, J. Daemen

"To minimize ore dilution induced by blast movement in surface mines, it is necessary to quantify such movement. This will enable more accurate location of the grade boundaries beneath the surface of a blasted rock pile before excavation. A method has been developed and tested to accurately measure the direction and magnitude of subsurface blast movement. This technique uses a cesium vapour gradiometer and a real-time, differentially corrected GPS system to locate pre- and post-blast position of magnetically enhanced target objects placed within blastholes inside a bench. The procedure developed does not require the blasted rock to be disturbed, and the movement information is available within a sufficient time to allow for modification of the selective mining boundaries for each surveyed blast. It was found that the maximum depth of target detection was 18 m, with the overall accuracy being measured as ±1 m (horizontally) and ± 1.2 m (vertically). IntroductionOre dilution is a critical concern for many mining operations. In some instances, it may be the cause of considerable mineral loss. Where the mineralization is finely grained, sedimentary and disseminated in nature, and exhibits no clearly defined visual ore/waste boundary, there is a heightened possibility for ore grade dilution. In most modern open pit gold mines, it is economically desirable to minimize dilution in the production process through the practice of selective mining by defining pre-blast ore digging boundaries, called digging polygons, on the preblast bench area. The polygons’ positions are defined by sampling the production drill holes, with the resultant assay and survey data being used to estimate the areas of specified grade content within the bench. Once the ore is blasted in the bench, the pre-blast locations of these digging polygons are flagged as designated areas on the broken ore pile. The purpose is for the loader operator to be able to recognize which areas of blasted rock are to be sent to the appropriate processing facility or to the waste dump."

Jan 1, 2001

By J. G. Stevens, S. W. Colley

"Selective separations of metals and ions in mineral extraction and refining are becoming more challenging as ore bodies become more complex and environmental pressures increase. The separation and containment of mercury produced in gold mining are a factor in the profitability and operability of mines. This paper will discuss the development and implementation of the Johnson Matthey HgFree selective mercury removal process. The process is designed to selectively recover co-leached mercury from either heap leach pregnant solutions at ambient temperature and low mercury concentrations, or electrowinning pregnant solutions at elevated temperature and high mercury concentration, without affecting gold or silver recovery. The process utilizes a highly selective adsorption-desorption step in which mercury is removed quantitatively by the HgFree adsorbent without adsorption of gold, silver or other metals present. Development of the original HgFree adsorbent has resulted in a process whereby mercury can be recovered as an inert salt and is never present as the free metal. The HgFree adsorbent can be regenerated and recycled in situ, and is capable of being reused multiple times. The overall process is compatible with existing gold mining and recovery practices and offers significant environmental and sustainability benefits, including reduction or elimination of the need to retort mercury with a subsequent reduction in potential mercury air emissions. Development of the HgFree adsorbent and process will be discussed along with a pilot operation at two operating mines.INTRODUCTIONMany gold ore bodies contain high concentrations of mercury which when extracted with cyanide, co-extract with the gold and other metals. This mercury is carried through the process with the gold, posing environmental and technical issues when it is separated from the doré. This paper describes a method to selectively adsorb mercury from the gold recovery circuit while it is in a soluble form, leaving gold to be processed as normal. The removal of mercury from the circuit eliminates the need for mercury retorting of doré and so reduces the potential environmental impact of fugitive emissions of elemental mercury."

Jan 1, 2016

By D. A. Sloan

THE Young Davidson mine is of particular interest because of the extremely low costs and also because of the novel method devised for pillar recovery. The outstanding feature of the mining system is its simplicity and regularity. The successful operation of this property was de-finitely assured by the rise in price of gold in 1934. The mine is situated in the southeastern part of Powell township, about forty-five miles southeast of Timmins, Ontario. The local town, two miles distant, in Matachewan, which is twenty-five miles northwest of Elk Lake, the terminus of a branch line of the Temiskaming and Northern Ontario railway. Mining is confined to one of a group of five claims. The ore occurs in a body of syen.ite porphyry which is intruded along a contact of Timiskaming conglomerates with Keewatin altered ruffs and greenstones. This intrusion extends in a north-easterly direction from Davidson creek for 3,300 feet, of which length 700 feet lies within the Matachewan Consolidated property. The maximum width of the mass is 700 feet; it tapers off as it extends east-ward. The Orebody.-The syenite porphyry is of three types, probably all differentiates of the same magma, but only one of them is gold bearing. This is a cherry-red, coarsely crystalline type which forms the central part of the mass. It is more brittle and more fractured than the others, and consequently has allowed easier access to the gold-bearing solutions. The gold has been brought in by a branching system of quartz veins and along minute fractures. It is mainly in the form of very fine 'free' gold, but also occurs in pyrite, which is the chief metallic mineral.

Jan 1, 1942

By G. Szilvay, P. Kinnunen, J. Salminen, V. Miettinen, O. Salmi, J. Mäkinen

This paper demonstrates experimental studies on bioprocessing of different waste streams. In Part I of this paper three tailings from mining industry were bioleached with mixed acidophilic culture in order to solubilize valuable metals, like copper, nickel, zinc and manganese to leaching liquor. Bioleaching resulted in > 70 %, > 85 %, 100 % and > 70 % leaching yields for Cu, Ni, Zn and Mn, respectively. However, contaminants like arsenic and chromium were not leached efficiently and they will cause challenges in residual solids and sometimes also in metal recovery from leaching liquor. Bioleaching resulted in 99 % leaching yield for copper. Part II demonstrates mine water treatment and also gold recovery from process liquids with biosorption method. The novelty of biosorption was finding that certain fungal species were able to be cultivated to self-immobilized systems, which are easier to operate than traditional suspended biomass methods. Biosorption resulted in more than 90 % removal for all contaminants, but was also seen to be gold selective.

Jan 1, 2014

By Lyle F. Smith

With the demand for larger diameter raises under all ground conditions and the increasing price of drill rods and operating costs, it was evident that there was a need for a raise borer with a variable-speed drive and fast-response torque limiting control. The raise boring machine described in this paper was developed after several years of market research and discussions with mine operators and construction contractors. This paper discusses the Ingersoll-Rand raise borers with the solid-state controlled DC motor drives. These machines have gained wide acceptance in the five-year period since being placed in operation and are designed to accommodate the range of raise diameters and lengths most required today.

Jan 1, 1978

By Roger C. Parsons

"The problems presented by ice formation and interference with processes, structures and mechanical operations in the mining industry can be expected to increase sharply as more of our mineraI needs are supplied from the far north. A process of rapid ice destruction is presented which lends itself to the effective removal or penetration of ice. Suggestions are offered for applying the system to problems related to mining activity in cold environments. The system can be readily adapted to large-scale operation, the reactant components being transported in crystalline form and volatilized on site.IntroductionThe number of operational mines in northern environments, relative to the number of mines in the temperate zone, will increase in the years ahead. This is not surprising, because:(a) in the past, those mines closest to centres of commerce had minimum transport charges and hence were more economic to develop;(b) great centres of commerce were far removed from northern environments;(c) the exhaustion of ores and lowering of grades in temperate zones now offset to some degree the extra transport costs applied to northern ores;(d) the abundance of excess energy in the north in the form of oil, gas and hydropower attracts mining as a means to justify its development; (e) assuming that the frequency of mineral occurrence north of the 52° N latitude is no different than south of it, there are many deposits waiting to be developed.As a result of current and projected activity in northern environments, we are faced today, and will be increasingly so in the future, with mining problems rarely encountered before-problems related to below-freezing temperatures. Engineering activity in permafrost regions will increase as new mining ventures are developed north of the 52° N latitude, roughly coinciding with the -1.1 ° C isotherm in Labrador, the upper temperature boundary for permafrost."

Jan 1, 1982

By I. Stefanou, J. Sulem

"In the last thirty years, the study of earthquake mechanisms has emphasized the major role of rock friction. Earthquakes appear to be the result of a frictional instability and occur by sudden slippage along a pre-existing fault or a plate interface. Multiphysics couplings play a major role in earthquake nucleation and seismic slip. The effect of shear heating and thermal pressurization may be of prime importance in the control of the stability of shear deformation inside the slipping zone. Other mechanisms in relation with thermal decomposition of minerals affect the pore pressure and the temperature evolution of the system, and can play a significant role in the extreme strain localization observed in field. The actual width of the localized zone is a key parameter for understanding fault weakening mechanisms. On the basis of field observations, laboratory experiments and recent advanced modeling, these phenomena are analyzed and discussed in order to bring some new insights in the understanding of earthquakes nucleation.INTRODUCTIONIn the last thirty years, the study of earthquake mechanisms has emphasized the major role of rock friction. Earthquakes appear to be the result of a frictional instability and occur by sudden slippage along a pre-existing fault or a plate interface (Scholz, 1998; Sykes, 1978). The conceptual model of spring slider system is commonly used to represent the interaction between an elastic crustal block and a fault zone. Stick-slip instability is possible if the softening rate of the shear resistance of the fault zone is high enough as compared to the stiffness of the crustal block. Therefore, weakening mechanisms that can explain how the frictional resistance of a fault decreases with slip and/or slip rate is of prime importance to understand how an earthquake nucleates. In recent years, several drilling programs in active faults (e.g. the Nojima fault in Japan, Boullier, 2011; the Aigion Fault in Greece, Cornet et al. 2004, the Chelungpu fault in Taiwan, Ma et al. 2006, and the San Andreas fault in the U.S.A. Ellsworth et al. 2000) as well as high velocity friction experiments (e.g. Tanikawa et al 2012a; Tanikawa et al. 2012b) have highlighted the physico-chemical processes involved in the nucleation of seismic slip (see for the example the review paper of Niemeijer et al. 2012)."

Jan 1, 2015

The concept and practices of co-extraction of coal and methane have emerged in recent years to improve coal mining safety and productivity, utilise methane resources, and reduce fugitive emissions in environments that involve multiple coal seams with low gas permeability. The system of co-extraction integrates two previously separate operations of coal extraction and methane drainage. The coal mining operation reduces the coal seam gas pressure and creates strata fractures that enhance gas migration and capture from mine workings and surrounding coal seams. An effective methane drainage operation produces a consistent and quality clean energy product and, at the same time, reduces the methane concentration in underground workings and the methane content and pressure in the adjacent coal seams. This is a significant benefit in preventing gas explosions and outbursts, and promotes a safer and more productive coal mining environment. In addition, the co-extraction with enhanced utilisation of coal mine methane directly leads to a reduction in greenhouse gas emissions. Presented in this paper are key results and outcomes of a major Asia Pacific Partnership project carried out from 2008?2012 by the Commonwealth Scientific and Industrial Research Organisation in collaboration with Huainan Mining Industry (Group) Co. Ltd., to develop and demonstrate advanced technologies at Pansan mine, Huainan, that promote the concept and practices of co-extraction of coal and methane. A comprehensive approach was adopted to assess fundamental strata and coal seam methane conditions during mining, and optimise mining sequences and coal mine methane capture systems. The project has not only demonstrated a practical approach and procedures of advanced co-extraction of coal and methane systems but also delivered significant benefits and outcomes in improved mining safety and efficiency, increased methane capture and utilisation, and reduced fugitive methane emissions at the Pansan mine. The total mine gas drained increased from 25.36 Mm3 in 2007 to 47.0 Mm3 in 2011, and the mine gas utilisation increased from 4.94 Mm3 in 2007 to 21.15 Mm3 in 2011. The improved methane capture resulted in reduced coal and gas outburst risks and methane concentration levels at the mine workings, provided a safe working environment for coal production, boosted the mining efficiency, and eliminated methane related incidents over the last few years at Pansan mine.

Aug 1, 2013

By Douglas Brand

"The data that many mineral processing plants make use of, is provided by samples taken from sampling systems which are inadequately designed or improperly maintained, and therefore cause detrimental effects to plant operations, production planning and metallurgical accounting! Poorly designed or maintained sampling systems will likely produce low probability samples which give the operator a false sense of security of the product and the process. If data is the basis for action (Flintoff, 1992, p.2), then using the resulting suspect or bad assays by operators, control systems, or metallurgist and administration personnel will act and make decisions which may adversely affect the profitability of a processing plant. Here we will discuss some of the fundamental sampling problems, propagation of errors and a method to estimate what impact this has on an operations Net Smelter Return.INTRODUCTIONIn order to control a mineral processing plant at its best potential, it is necessary to obtain the best possible measurement results of the metal or mineral in question. The sample which is delivered to a measuring instrument, or lab, needs to be of the highest probability to be able to achieve this. This paper will discuss the effects of sampling errors on grade / recovery and grade / Net Smelter Return (NSR) and provide a method to estimate the monetary advantages of using probabilistic sampling in a processing plant.REVIEW OF SAMPLINGSampling, by definition, is the removal of a small representative portion from a total consignment, or flow, for the purpose of accounting or process control.• A sample can only be considered representative, if each and every increment collected, in each of the sampling stages, is representative.• Each particle of the sampling lot must have the same probability of being included in the final sample.• If both of the above conditions are met, then the final sample will be representative of the complete sampling lot.It is commonly known that in order to take truly representative and probabilistic sample, best practices indicate that:• The total stream should be sampled.• The sample cutter should intersect the sample at right angles to the flow.• The sample cutter should travel through the stream at a linear and constant speed and the speed deviations should be less than 5%."

Jan 1, 2016

By L. M. Nolan

Chemical Mechanical polishing, or CMP, has four components in the polishing interface; namely the polishing pad, the polishing fluid, the abrasives in the fluid, and the surface being polished. Understanding the way that load is transferred between these components is key to understanding and predicting wafer polishing. Numerous models of CMP and the different load sharing arrangements which occur between these four components have been proposed. These include models by Luo and Dornfield (1) and Fu, Chandra and colleagues (2). Other models focus on just one or two loading arrangements, such as `hydroplaning' when all load is transmitted by the liquid in the case of Runnels and Eyman (3). In this work, we consider four possible combinations of load transfer from pad to wafer in CMP. These combinations are listed below in Table 1 and are illustrated schematically in Figure 1. It is important to note the role of scale in this process; the illustrations in Figure 1 are drawn to scale from actual profilometer scans obtained over a length of 5 with particles of 150 nm in diameter. Table 1 - Load Transfer Combinations Load Regime Illustration Wafer - Fluid - Pad Figure la Wafer - Particles/Fluid - Pad Figure lb Wafer - Particles - Pad Figure lc Wafer-Pad Figure ld The interest in load-sharing between the system components is because some configurations are anticipated to achieve higher polishing rates than others. For instance, in hydroplaning, or hydrodynamic lubrication, the lateral force exerted on the polished surface by the particles can be no higher than the fluid shear force developed in the gap between the pad and wafer. This is not expected to generate high rates of material removal from the surface (4). For contact that is largely between the pad and the wafer, such as the regime depicted in Figure ld, the lateral load is transmitted to the wafer by the pad and is hence limited by the pad's low rigidity. This regime is not expected to generate high material removal rates either. The highest levels of material removal are expected from regimes where the mechanical load exerted on the system is transmitted by the particles, in combination with either the fluid or the pad. Under what circumstances does the polishing regime change from one to another? What must occur in order to initiate or terminate contact between the system components? This is an ongoing question in the field of tribology, and has traditionally been viewed in terms of the pressure and velocity applied to the system, the thickness of the fluid film between the two surfaces, and the roughness of those surfaces (4). In this paper, we propose a new mechanism ? that the load on the particles may be sufficient to totally embed them in the polishing pad, at which point they are no longer able to transmit load and polish the wafer surface. This is illustrated schematically in Figure 1(d).

Jan 1, 2010

By D. Hamilton

The electrode of a PEM fuel cell consists of two distinct sections - the catalyst layer and the porous transport layer (PTL). There are several kinds of PTL material, although all use carbon fibres as the solid fraction. The fibres can be matted to form a paper, woven into a cloth, or chopped to form a felt. Despite the different morphologies of the media, they are all anisotropic in structure, that is the majority of continuous fibres lie perpendicular to the direction of bulk transport. Currently, no models account for anisotropy and all transport coefficients are calculated as volume weighted averages or from empirical correlations (not developed for fibrous porous media). The present work presents a new methodology for determining anisotropic transport coefficients in fibrous porous media. A numerical experimentation process is employed wherein random samples of the PTL are generated and used to solve a diffusion transport equation. Effective transport coefficients are determined by integration of flux across the domain boundaries once a steady state solution has been reached. Multiple random samples at each porosity are generated in order to predict statistical variance. The results are correlated for ease of implementation in full PEM models.

Jan 1, 2005

By D. Saramak, Z. Naziemiec

"Chalcedonite is an unique rock due to the relatively small area of its occurrence. It also possesses multi-raw-material features therefore it should be given a special protection aiming at its complete and optimal utilization. It is the natural sedimentary rock and the only mine in Poland, located in Inowlodz, where the opencast mining from “Teofilow” deposit is carried out.Chalcedonite mainly consists of cryptocrystalline and microcrystalline chalcedony together with small amounts of autogenous and detrital quartz. The chalcedony itself is a fairy common mineral and many forms of its occurrence is known, some of them are semi-precious minerals. Among the most popular ones following can be found: agate, bloodstone, onyx, carnelian, chrysoprase. Many countries own chalcedony deposits: Australia, Brazil, India, Canada, Namibia Russia, South Africa. However chalcedony in its pure form does not occur in the mentioned chalcedonite rock. The pores, which take usually from 5% to 25% of volume and have sizes smaller than 0.5 mm, are the characteristic feature of all chalcedonite forms. The paper presents some crucial problems of its processing together with most significant directions of its applications. New method of chalcedonite enrichment based on densimetric separation (patented in Poland) is presented. Results of investigation show that the obtained products can increase quality of concrete and filter grits."

Jan 1, 2016

By L Mariani, G. Mendoza-Suarez

In this investigation, TiH2 powders were coated with copper and nickel by electroless plating to delay hydrogen evolution. Copper-coated samples were found to have a mixed acicular (2D growth) and cauliflower (3D growth) morphology whereas the nickel-coated samples had a cauliflower morphology. Examinations of the coated powder cross-sections revealed that the coating thickness ranges from 0.2 µm to 4 µm. Uncoated areas on the powder surface and coating flakes unattached to TiH2 particles suggest poor adhesion between the coating and the substrate. The phase transformation undergone by the TiH2 during dehydrogenation was studied in samples taken at intermediary points in the heating cycles and examined by XRD. The findings reveal that as the powder is heated from room temperature to 800°C, it changes from TiH1.971 to Tiu and to aTi. Differential Thermal Analysis (DTA) was performed to study the effects of the coatings on the temperature of hydrogen release. It was found that increasing the number of plating iterations, and therefore the thickness of the coating, creates a significant shift in the temperature of gas release.

Jan 1, 2006

By C. G. McLachlan

Professor H.E.T. Haultain: To me from time to time the urge comes to say the agreeable thing as well as the disagreeable in commenting on the work of others. It is a prerogative of age. I don't apologize. To myself I justify my action as based on a long experience of the matters with which I deal, and I like to tell myself that I have a certain responsibility in such matters on account of my detached position. This Noranda article is a very fine contribution concerning Canadian milling, and I am surprised that no word of commendation or thanks has appeared concerning it in the BULLETIN. There is altogether too much written in these days by men rushing into print, concerning laboratory work, that has not been tied into, nor has resulted in application in the field. The authors of this paper have not rushed into print. The preparation of this paper was evidently an uncongenial task. If the authors had been that way inclined, it could have spread over several lengthy papers. It is an important article because it represents an enormous amount of work in the laboratory and the mill, extending over a period of sixteen years, and resulting in fine metallurgical and economic results with a very difficult and involved problem. It is a fine article because it is so well prepared and presented. It deals with an unusual ore condition, but there is much in it of use to every cyanide millman. It leaves very little room for criticism, though there may be differences of opinion in regard to some of the chemistry phases with which I am not conversant. I am struck by the enormous amount of persistent, painstaking, conscientious research work involved, and in the careful, sincere way in which the methods and difficulties have been described. Persistence and sincerity are the key note of the effort. It should have a good educational effect on the rising generation of millmen, and it should continue for long as a work of reference, and a spur to others. There has been an important by-product, the training and development of the young men engaged in the work. Three of them became superintendents of important mills. One was sought for important work in Africa, another has joined a large research organization in the United States.

Jan 1, 1946

By R. W. Allgood

"THE world-wide shortage of elemental sulphur, which became sharply apparent in 1950, has focused attention on the commercial exploitation of sulphur-bearing materials such as pyritic ores, sour natural gas, and smelter gases. Although there •are no known commercial deposits of elemental sulphur in Canada, there are vast quantities of these sulphur-bearing materials. The International Nickel Company of Canada and Canadian Industries Limited have for many years collaborated in an effort to develop economic processes for the recovery of sulphur from the smelter gas arising from Inco's metallurgical operation at Copper Cliff, Ontario. While sulphuric acid has been •produced at Copper Cliff for over twenty years, recent developments will result in a 60 per cent increase in acid production early in 1952 and, later in the year, in commencement of the operation of the largest single unit ever erected for the manufacture of liquid sulphur dioxide.The purpose of this paper is to discuss •briefly the general factors associated with the recovery of sulphur from the Copper Cliff smelter gases and to describe the sulphuric acid operations and the liquid sulphur dioxide development.Processes for the manufacture of elemental sulphur, liquid sulphur dioxide, and sulphuric acid from sulphur-dioxide-bearing smelter gases are well known and in some cases •highly developed."

Jan 1, 1952