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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 Minghui Li

China is the largest coal producer in the world. In 2012, the coal production in China is 3.65billion tonnes, accounting for approximately 49% of global coal production. The raw coal production in 2012 was 3.8% more than the year 2011. 56% of total raw coal has been washed. The increase in raw coal production also promotes technology to be developed and brings separation capacity become larger and larger in coal processing in China. At present, over 40 extra-large scale coal preparation plants (each plant has capacity of more than 10 Mtpa) are in operation in China, the largest one is 32.5 Mtpa. Heavy medium separation are widely used in new built coal preparation, the washing limit for thermal coal feed lower and lower, the equipment selection tends larger which brings the whole washing system simplified, the local equipment developed and manufactured are more and more used. By discussing designs of several typical thermal coal preparation plants and coking coal preparation plants in China, this thesis introduces the current design of China?s extra-large coal preparation plants, and sums up the prevailing design features and trends of extra-large coal preparation plants.

Aug 1, 2013

By D. Sharma, A. K. Singh, R. Singh, P. K. Mandal, M. Sarkar

"This paper deals with the stability investigations carried out at the XIVth seam of Jitpur colliery. The study was conducted to investigate the possible causes of roof cavity formation and face spalling at the middle slice face of block-3 longwall panel and to suggest remedial measures. The instrumentation and monitoring work was carried out in the panel over a period of nine months. On the basis of observations, it was found that if the maximum face span was reduced from the existing 4.8 m to 3.6 m, and if the face time schedule cycle was reduced from a maximum of 37 days to about 18 days, this problem could be eliminated. The recommendations of CMRI have been implemented in the middle slice face of block-4 panel with success. IntroductionModerate to steeply dipping, undisturbed seams of uniform thickness are worked by way of inclined slicing parallel to walls. In this method, the seams are treated as a combination of several moderately thick seams dipping parallel to roof and floor. Numerous variations of multislice mining have been used worldwide to get high coal recovery under local conditions of geology, subsidence control, proness to spontaneous combustion, statutes and economics. Multislice mining can proceed either downward descending from the roof or upward ascending from the floor. Ascending methods require backfill behind the working face to provide a base for the next slice. It is also adopted for surface protection against subsidence or mining under a massive roof. This paper presents a scientific study conducted in Jitpur colliery, IISCO where a 9 m thick seam is mined in three slices in ascending order with stowing."

Jan 1, 2002

By R. B. Fermor

"The tyndalloscope is used in Europe for dust-hazard assessments in both coal and metal mines. Dust-hazard conditions can be directly evaluated by the tyndalloscope in many underground working situations, once the basic standard table or tables have been prepared from representative mine-rock samples.The tyndalloscope is excellent, in many cases, for diagnostic dust sampling during a working shift, because individual readings can be taken to within three-minute intervals. The limitations of the tyndalloscope are also discussed.The author suggests that a combination of both the tyndalloscope and gravimetric sampling methods would be an ideal match for most mine dust-hazard assessments."

Jan 1, 1970

By M. N. Collison

"In 1960, with the opening of the Chisel Lake mine near Snow Lake, Manitoba, the Hudson Bay Mining and Smelting Co., Limited, commenced a new phase in their mining operation -that of bringing ore to Flin Flon over 100 miles of railroad.The schedule of operations required to accomplish this, together with an outline of some of the problems of handling ore at 40° and 50,0 below zero, are discussed. The facilities required to thaw and unload from twenty to fifty cars per working day are also described."

Jan 1, 1966

By P. S. Arthur

The copper I SAS MELT? process is a submerged lance bath smelting technology. In the 20 years since the process was first demonstrated on a semicommercial scale at Mount Isa in north-west Queensland, Australia, copper ISASMELT? plants have been constructed to treat concentrates or secondary raw materials around the world. The process is operating in smelters in Australia, the USA, Belgium, India, Germany, China and Zambia. ISASMELT? plants have been installed to improve the environmental performance of operating smelters and reduce costs for smelting companies. A new copper furnace is being commissioned at Southern Peru Copper Corporation in early 2007, while more furnaces are under design for installation in Kazakhstan and Peru. Copper ISASMEL T? plants are supplied as complete technology packages including engineering design services for the furnace and key ancillaries, supply of core equipment, provision of intensive training programs in operating plant environments and commissioning assistance services. The proven technology transfer process ensures successful implementation of submerged lance bath smelting into large scale plants. This paper summarises developments at recently constructed copper ISASMELT? plants.

Jan 1, 2007

By C. Allen

In 2004, Boliden Odda underwent an extensive modernisation project targeting mainly the leaching section of the plant. Direct leach technology was introduced as part of this project. The Direct Leach process, developed by Outokumpu, is an atmospheric oxidative leach of zinc sulphide concentrate. The effects of this new processing operation on behaviour of iron in the plant are discussed. As well, the filterability of the new residue on belt filters prior to its deposition in mountain caverns is also discussed. The solids from the direct leach process have been analysed by scanning electron microscopy, and the results of these analyses are presented.

Jan 1, 2006

By T. E. Warren, K. W. Bowles

"IntroductionTHE PROBLEM of producing synthetic liquid fuels from coal and other raw materials is of increasing importance in Canada as well as in the United States. This is due, to a large extent, to the continually increasing demand for gasoline and other liquid products which are now obtained solely from petroleum. The United States has reached a position where domestic supplies of crude petroleum must be augmented by imports and Canada is still a long way from self-sufficiency. In the event of war, there might well be an immediate need to find supplementary sources of liquid fuels. It is, therefore, expedient to consider alternative sources of production now -well in advance of the time when supplies of petroleum may prove inadequate to meet requirements.The purpose of the present paper is to give a short review of the history of liquid fuel production from coal, to describe briefly the research sponsored by the Federal Government on the coal hydrogenation process, and finally to evaluate the present status and future trend of the synthetic fuel industry, with special reference to necessary research work.History of the Oil-From-Coal IndustryThe history -of coal liquefaction began in 1913, in Germany, with the work of Frederick Bergius. His first approach to the subject was not deliberately planned."

Jan 1, 1952

By B. S. Prosser, K. G. Wallace, A. Akansobe

"This paper describes a ventilation project at the Wassa gold mine in Ghana. Golden Star (Wassa) (GSWL), a subsidiary of Golden Star Resources, owns and operates the mine. Golden Star holds a 90% interest in GSWL, while the Ghanaian Government holds the remaining 10% ownership, earning a 5% royalty on the gross revenue of GSWL’s gold production. Construction of the underground mine began in mid-2015 and pre-commercial production started in June 2016. Commercial production from the underground mine was achieved in January 2017. This paper describes the ventilation studies performed to support the initial development and production at the mine. The initial ventilation design included four, parallel surface exhaust fans. Future designs will include booster fans, new primary fans, and additional connections to surface. The paper describes the long-term ventilation planning goals and expectations as the mine achieves a production of 4,000 tpd with truck haulage to surface.INTRODUCTIONThe Wassa Gold Mine is located in the southern portion of the Ashanti Greenstone Gold Belt in Ghana, northwest of Tarkwa as shown in Figure 1. The mine has been in production as an open pit since 1998, with some minor disruptions, but the surface minable reserves have become exhausted and the mine started a transition to an underground operation in 2015. The underground mine was initially developed with twin decline accesses extending from the base of the open pit to the mining areas. The mining method selected was sub-level open stoping with cemented rock backfill. The original production level for the mine was 2,500 tpd with ore and waste transported by trucks hauling in the ramps to surface. In 2017 the production goal was set to increase to approximately 4,000 tpd. This resulted in an increase in the truck haulage fleet in addition to a significant increase in ventilation requirements. This paper describes the ventilation upgrades at the mine as it transitioned from a surface to an underground operation and the adjustments the ventilation system needed to make in order to accommodate a significant increase in production"

Jan 1, 2019

By L. Dorador

"In block caving projects, the rock mass fragmentation process plays a controlling role in the design and success of the operation. Poorly understood, however, is the secondary fragmentation that occurs as blocks of caved ore move through the draw column and interact with one another. The initial size of these blocks can be considerable, as can their strength and stiffness as the presence of non-persistent joints and veining will be variable. Intuitively, more planes of weakness within the blocks should facilitate early fragmentation, but this assumption could depend on additional factors such as contact type between adjacent blocks and loads imposed through varying heights of the draw column. This paper reports the findings from a laboratory investigation examining the role of block strength and planes of weakness on secondary fragmentation. Testing was carried out on small-scale concrete cubes of uniform size, with and without embedded planes of weakness. The results obtained demonstrate the significance of veining and other planes of weakness on secondary fragmentation under one-dimensional compression, and allow for the development and constraint of empirical guidelines.INTRODUCTIONThe fragmentation process during block caving involves the initial (primary) fragmentation of rock in the cave back through stress-induced fracturing, release and fall of individual blocks onto the broken ore muck pile. This is followed by secondary fragmentation involving splitting and rounding of blocks as they move downwards through the draw column towards the draw point. The degree of secondary fragmentation achieved involves many variables related to the mechanical properties of the rock blocks as well as different operational factors. With respect to the block properties, the presence of planes of weakness in the form of veining and non-persistent joints is a topic of special interest given the significant influence it potentially has on the overall fragmentation process. However, the inherent heterogeneity and variable size of individual blocks generated from the cave back makes it difficult to develop any empirical relationships relating secondary fragmentation to compressive loading based on insitu observations and mine data. More preferable would be to keep constant block parameters, such as shape (aspect ratio and angularity) and size, through controlled laboratory testing. This work presents an efficient technique to fabricate concrete cubes in order to keep constant different block properties. These are then tested under one-dimensional compressive loading. The objective of these tests is to emulate a tight packing condition of single blocks such as that which would occur when the air gap between the cave back and broken ore in the draw column is small. When the air gap is small, detached blocks are unable to fall and rotate but instead maintain a very tidy arrangement with minimal voids left between adjacent blocks."

Jan 1, 2015

By H. G. Harper, R. C. Hart

"The Mississagi quartzite is the basal formation of the Quirke Lake trough. As it is traced around the rim, a gradual change in dip is observed, as follows:Northwest corner 50 degrees south.Algom Quirke mine 34 degrees south.Quirke Lake 25 degrees south.Whiskey Lake 22 degrees west.Pecors Lake 25 degrees north.Algom Nordic mine 18 degrees north.Elliot Lake 11 degrees north.Pistol Lake 5-7 degrees west.Thus the apparent synclinal axis is a curving east-west line lying closer to the north limb than to the south. The axis appears to plunge west at about 5 degrees.The Huronian sediments lie on a basement of granites, gabbros, and volcanics. Diamond drill evidence indicates that this basement has a surface of peneplanation, and that the areas of soft basic rock have a smoother topography than the granite. For the most part the orebodies at the Quirke and Nordic mines overlie a basement of soft basic rock.The Mississagi formation is the host rock of the deposits, and its primary structures are suggestive of the conditions under which the conglomerate beds were deposited. Cross-bedding is common, although normal bedding varies from thick to thin to essentially lacking. Grain gradation is not common. Where coarse and fine grains occur together, the coarse tend to be more rounded than the fine. These features are characteristic of shallow-water deposits, laid down above the lower limit of wave action. Therefore, the quartz-pebble conglomerates probably represent ancient water courses, bays, beaches, and bars.The causes governing the creation of the trough can only be conjectured, but there is evidence that both subsidence and compressive stresses played active roles. Drag-folds in argillite beds near Whiskey Lake indicate compressive stress. On the other hand, gentle crumpling in thin-bedded limestones on Quirke Lake is probably due to pre-induration slumping and folding. If strong compression had been widespread within the trough, one would expect drag-folding and shearing of the incompetent beds to be more general. Two large-scale, fold-like structures were mapped by Collins, but their axes do not parallel the trough axis, and they are therefore not related to the major structure."

Jan 1, 1949

By P. R. Geoffroy

Extensive and Intensive Prospecting As often pointed out, the search for new ore deposits may be carried on along two widely divergent lines. It may be either extensive or intensive. By extensive prospecting we mean a search for mineralized outcrops conducted over large and more or less virgin tracts of land, followed by a test of the practical value of any discovery made, the test being limited to the immediate vicinity of the outcrop. Extensive prospecting, was, in fact, the only policy known to the early prospectors. of the American continent and is still the rule in the remote sections of the Canadian Shield and in the African wilderness. It can be further characterized by the lack of emphasis placed on geological and other technical means as an aid to the search for ore. However, very little virgin ground is left, nowadays, for a man or a company to test their luck, and whatever is left is so remote from the necessary means of development that any new discovery will require considerable delay and expenditures to be amenable to profitable mining. On the other band, a great many of the favourable and still unexplored areas (and this is particularly true in Canada) are overburdened to such an extent that outcrops of bed-rock are extremely scarce and extensive prospecting is nearly impossible. Intensive prospecting, to the contrary, must be understood as a detailed search for ore carried on over limited areas in districts already known to be mineralized and covering regional structures whose relation to mineral deposits bas been estahlis.hed with a fair degree ot certainty. The search for deep-seated deposits in the vicinity of successful mines is a perfect example of intensive prospecting. As a matter of fact, the majority of the geologists employed by the mining industry are engaged in some kind of intensive prospecting.

Jan 1, 1950

By W M. Gilchrist

This paper gives an estimation of the future requirements of the western world in relation to energy re-sources. It then goes on to outline the role that atomic power -with its basic raw material, uranium -will play in supplying these energy requirements. Canada's position in this picture is covered, and some interesting forecasts are made. Introduction I T is possible that the following remarks will appear to have more to do with power than uranium. However, to fully comprehend what is in store for the Canadian uranium mining industry, we must be able to estimate the potential requirement, and, to do this satisfactorily, a thorough understanding of the circumstances that will give rise to that demand is necessary. The growing need for electrical energy will play by far the major role, as large tonnages of uranium will be required for its generation. The nuclear weapon has, up to the present, comprised the major market for uranium.

Jan 1, 1964

By L. P. Connolly, M. J. Fraser

"Hydraulic transport of solids has long been an important technique in mining and beneficiation. More recently, slurry pipelines have proved to be economic for longdistance overland transport of many commoditieis, including iron ore concentrates and coal. Now, the Marconaflo system brings the many advantages of hydraulic transport to bulk storage, loading, transportation and unloading of ships and other carrying equipment, thus providing important new means for delivering mineral commodities to market. In this paper, the authors describe the Marconaflo system and the potential economies which can be realized when applying it for loading, transporting, storing, reclaiming and blending a variety of mineral commodities, using several commercial installations as examples."

Jan 1, 1972

By Michael McClintock, Bern Klein

"The high pressure grinding roll (HPGR) is a relatively new comminution technology that is gaining popularity for providing energy efficient solution to hard rock mining operations. A significant barrier to increased adoption of HPGRs is the present requirement for large amounts (excess of 2 tonnes) of sample for pilot testing, which may not be possible for most early stage projects. Three methodologies have been developed at NBK Institute of Mining Engineering at the University of British Columbia that may be used for sizing design optimization of HPGR circuits. All three methodologies use a MTS pistonpress to simulate HPGR comminution. These tests are capable of providing information regarding energy consumption, energy breakage relationship, reduction ratio, and product size distributions. In a period of slow economic development, these methodologies are critical to allow the industry to cost effectively understand the operational benefits of HPGR implementation. This paper examines previous test work done at UBC, as well as the development of an HPGR and piston press database for use in sizing and budgeting of HPGR circuits.INTRODUCTIONCurrently, the mining industry faces several challenges due to falling commodity prices and escalating costs. This has applied pressure for operations and projects to reduce costs and improve project economics. In addition engineering and metallurgical budgets have shrunk as companies try to conserve cash. Improvements and optimization of milling and comminution circuits is one area project economics may be significantly improved. By considering alternative comminution technologies such as the high pressure grinding roll (HPGR), energy operating costs may be greatly lowered. Many have begun to implement HPGR crushing as an alternative to semi-autogenous grinding (SAG) mills, including KGHM and, Sierra Gorda, and Freeport Mc-MoRan’s Cerro Verde operation. However, implementing new technology for companies with little or no HPGR experience may not be practical. An operator must consider both feasibility and economics of a circuit. Currently, consideration of the HPGR requires expensive pilot scale testing for which large sample sizes are needed. In addition, few laboratories are equipped for running pilot scale HPGR test programs. Furthermore, the results of pilot HPGR testing are dependent on the quality of the sample, which cannot represent variations across a deposit. In contrast, ball mills and SAG mills can be sized using the Bond Mill Work Indexes that require a small amount of sample which enable a number of different geological blocks to be tested to allow engineers to have a complete understanding of how the comminution circuit will perform for the life of mine."

Jan 1, 2016

By E. B. Spice

"IntroductionExperience at Eldorado has been gained with a variety of mill feeds. That is, the actual mode of occurrence of the pitchblende varies to such an extent that gravity concentration has at times been decidedly unattractive and at others highly successful. Because of this, the type of ore necessary for economic recovery of pitchblende have become well known. Also, those types which do not lend themselves to gravity concentration have become familiar. In general, it may be said that when the pitchblende occurs free, to a large extent, from sulphides or arsenides of high specific gravity, and when the bulk of the pitchblende is localized rather than disseminated, excellent recoveries, high ratios of concentration, and good grades of concentrates , will result from proper gravity concentration. On the other hand, if the ore contains pitchblende intimately or otherwise mixed with large quantities of arsenides or sulphides, or if the pitchblende is finely disseminated, gravity concentration alone will yield high recoveries only at the expense of very low-grade concentrates and low ratios of concentration.According to Taggart, the ease with which gravity separation may be effected is determined by the value of the following ratio: []It is stated that when the ratio is above 1.75, gravity separation can be expected to be easy. Thus with pure U308 (S.G. over 9) and gangue consisting chiefly of siliceous material, the process can he expected to be entirely successful even when carried on at very fine sizes. Unfortunately, the term pitchblende covers a great diversity of material. Although some of the mineral occurs pure enough to have a specific gravity of about 7, the average is much lower than this and is probably well under 5. Some of the pitchblende particles have a specific gravity so low that gravity concentration fails completely. It may also be said that no degree of grinding will produce free pitchblende of sufficient density from such particles. This, then, represents the most important limitation to the application of gravity separation to pitchblende ores."

Jan 1, 1950

By S. Markstrom

The Boliden AITIK copper mine is located 100 kilometres north of the Arctic Circle in northern Sweden. A pre-feasibility study was conducted in 2005 with the aim of increasing the capacity of the existing processing plant. After analysis, options to upgrade the existing plant were abandoned in favour of building a new processing plant, with higher capacity and therefore greater profitability. A new plant could be designed with greater flexibility to make potential future expansions easier. A feasibility study for a new 36 Mt/y processing plant including fully AG grinding circuits and flotation was completed in 2006. The project was approved by the Boliden board shortly thereafter. Construction started in the beginning of 2007 and was completed during 2009. Commissioning of the new plant was undertaken in the first half of 2010. The grinding circuit consists of two lines with each line consisting of a 22.5 MW AG mill and a 10 MW Pebble mill in closed circuit with a spiral classifier. The nominal production level is 2 200 t/h for each grinding line. This paper presents the start-up and operation of the grinding circuit.

Jan 1, 2012

By W. H. Moore

It seems necessary, at times, that we should reconsider some of the more obscure causes that lead to explosions of gas and coal-dust in mines, in the hope that a recapitulation will keep before us that old and true saying "eternal vigilance is the price of safety". This explosion, while not extensive (resulting in only two much to be regretted deaths) enlarged our vision as to the possibility and probability of other explosions with more disastrous results. As this is only a partial report I shall have to omit many things that are generally included in describing a mine explosion. The mine was worked exclusively with electric cap-lamps -only firebosses and other officials carried safety-lamps. All shots were examined and fired by firebosses with a small hand-battery. Monobel was used exclusively for blasting, and clay for tamping. The system of haulage iri use was main-rope and winches, horses being employed for gathering. Compressed-air was the motive power for all winches and pumps, excepting the pumps at the shaft-bottom which were steam-driven. The mine was wet with practically no dust anywhere, except what was being made at the coal-face in the getting of the coal. Gas was found occasionally, generally in the brushing, especially where the brushing was carried up to a small seam, 2 to 6 feet above the main seam. The place where the explosion took place was known as Leigh's heading, which was being driven to the rise, immediately inbye of the siding (off No. 1 left, off the new slope) and was about 90 feet up from the level.

Jan 1, 1926

By E. Ghali

"Corrosion of support system components (e.g., bolts, mesh, plates) is a safety and economic concern in underground mines. This paper reports the results of a five-year study wherein corrosion coupons were installed at select locations in participating mines, recovered at regular intervals, analyzed for signs of corrosion, and tested to quantify loss in capacity. Complementary tests were conducted on recovered mesh and friction bolt specimens. The data provide insights into contributing factors for support systems corrosion, which aid in the selection of appropriate support strategies and reliable assessment of the useful life and need for rehabilitation of a support system.RÉSUMÉ La corrosion des composantes des systèmes de soutien (p. ex. boulons, grillages et plaques) est une préoccupation économique et de sécurité dans les mines souterraines. Cet article présente les résultats d’une étude de cinq ans pendant laquelle des coupons de corrosion ont été installés à des endroits spécifiques dans les mines participantes; ces coupons ont été retirés à des intervalles réguliers, analysés pour des signes de corrosion et mis à l’épreuve pour quantifier la perte de capacité. Des essais complémentaires ont été effectués sur les grillages récupérés et sur les échantillons de boulons d’ancrage. Les données aident à comprendre les facteurs qui contribuent à la corrosion des systèmes de soutien, ce qui est utile dans le choix de stratégies appropriées de soutien et pour une évaluation fiable de la durée de vie utile et du besoin de remise en état d’un système de soutien."

Jan 1, 2015

By J. L. Miller, R. W. Burns

This paper sets out the various phases of bringing a merchant bar mill into operation from feasibility consideration through financing, design and scheduling to completion.

Jan 1, 1967