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By H. C. Gunning

SOME small vanadium-bearing deposits on the west coast of British Columbia about 100 miles north of Vancouver are of interest for several reasons. They are of a type that is, so far as we know, unique. They are difficult to identify as being vanadiferous so that, unless they are described, other similar deposits could easily pass unrecognized. Furthermore, although none of them has as yet been proven to be of commercial proportions, no good reason is apparent why larger, and therefore valuable, deposits should not occur under similar geological conditions. The original discovery on Quadra island was made in 1932 and has been recorded by H. V. Ellsworth and H. C. Gunning (l). Since 1932, prospecting in the area has revealed other similar deposits, one about a mile south of the original and another some ten miles to the east, near Menzies bay on Vancouver island. The Quadra Island showings are a mile and a half north of the head of Gowland harbour, a small inlet that is easily reached by gas boat from Campbell river, about four miles to the southeast on Vancouver island. The deposits were examined by the writers in the spring of 1943 in connection with field work sponsored by the Department of Geology, University of British Columbia. We are indebted to Mr. G. A. Dirom and Mr. Lothrop, of Vancouver, for helpful data on the Menzies Bay deposits, and to Dr. V. Dolmage for making a brief trip to Gowland harbour and discussing the deposits.

Jan 1, 1944

By Forrest A. Kerr

Northern British Columbia is a term which probably conveys to various individuals quite different meanings. To the average person it signifies an area of indefinite size and indefinite position which may start at Prince Rupert, Stewart, or somewhere else, and end at Alaska or .the Yukon. Many people, in their conception, fail to encompass in their mind's eye that vast tract of land lying ~o the east of the panhandle of Alaska. Few realize that the area north of an east-west line through Stewart represents more than one-third of the Province and is, of course, the part most appropriately designated as northern British Columbia. This section, more especially the northernmost 100,000 square miles, from political, geographic, and economic viewpoints stands isolated perhaps more than any other part of British Columbia. Unlike the rest of the Province, it has no coast line, being cut off from the Pacific ocean by a narrow strip of Alaska. It is bounded on the north by the Yukon, and on the east by Alberta. In the south this northernmost 100,000 square miles is limited by a divide of rugged mountainous country separating the drainage basins of the Stikine and Liard rivers from those to the south.

Jan 1, 1929

By Z. Q. Yue

Many large rock avalanches and/or landslides have occurred in mountainous regions around the world. Their occurrences are normally rapid and unexpected, which can cause disasters. They have been investigated extensively by many researchers and engineers since the 1903 Frank Slide on Turtle Mountain, Alberta, Canada. They are one of the most peculiar phenomena because the rock debris of more than one million m3 can move over the horizontal distances exceeding those expected from conventional friction physics. This paper presents a gas cause hypothesis responsible for the large rock avalanches. It is the migration and expansion of a certain amount of highly pressurized and dense natural gas mass from deep geological grounds into the mountainous rock mass slopes. The natural gas with high pressure and density can escape from the deep geological ground and flow through faults, weak zones and/or porous channels into the rock mass forming a mountainous slope. The rock mass forming the slope has the high tensile and compressive strength and can resist the initial loading of the gas mass migrated into and stored in their voids, pores, holes, gaps, openings, apertures and cavities. With time, more and more gas mass from deep ground can migrate into and stored in the slope rock mass. Eventually, the peak equilibrium of forces and deformation reaches. The expanding power of the gas in the slope rock mass would instantly and rapidly break, erupt and/or explode them. The compressed and dense gas mass would mix, flow and expand together with the broken rock debris mass and continue offering their remaining expanding powers to the moving and sliding debris mass. As a result, the rock debris of large volume can reach the runout distances exceeding those expected from the conventional friction physics. The gas would escape into the sky and the solid rock debris would remain on the ground spreading over large ground area. The 1903 Frank Slide is examined to show this gas cause and mechanism in mountainous regions.

Jan 1, 2015

By C. Karpuz, Y. S. Istanbulluoglu

This paper describes the results of convergence measurements conducted about five years for the re-use gate roadways at OAL lignite mine in Turkey. Double lignite seams separated with a marn layer, are mined with long-wall retreating mining system at the mine. Rib pillar has been abandoned and gate roadways were planned to be packed for the re-use of full extraction. Various packing systems have been attempted, namely three rows of woodenchock, one row of wooden chock plus concrete wall and concrete wall only. The re-use of maingate roadways packed with wooden chock yielded 62% of closure. Lastly developed concrete packing of 3 meters wide and specially developed support set composed of three friction props and a cap, which is a modification of yieldable set, have successfully maintained the main and tail gate roadways stability with a total vertical convergence of 32%. Good correlation has been established between pack stiffness and floor heave as well as maingate and tailgate convergences. The elimination of rib pillars by re-use of gate roadways increased the coal recovery by 20% and decreased the development/production ratio from 0.065 m3/ton to0.022 m3/ton.

Jan 1, 1997

"In many gold deposits, a reasonable amount of the gold that remains in the cyanide leach tailing is associated with pyrite. Some gold plants have found it economical to incorporate gravity circuits on the cyanide leach tailing to recover the gold bearing pyrite before subjecting it to fine grinding, then recycling the ground pyrite back to the cyanide leach circuit. For low grade gold deposits the loss of gold bearing pyrite is exacerbated as the broader process economics normally favour a coarse grind (> 150 ?m). An option that has received attention over the last decade is to recover the gold bearing sulphides in the milling circuit by gravity, similar to the widely-practiced gravity recovery of free liberated gold. The modelling and simulation of a gravity gold circuit in a milling flowsheet is relatively simple compared with a gold bearing pyrite circuit, as the recycle advantages and breakage functions for gold and pyrite are quite different. This current work represents an attempt to simulate the gravity recovery of gold bearing sulphides in a milling circuit that also incorporates fine grinding, using relatively simple simulation models. The simulation results are further explored with reference to the economics of this type of circuit.INTRODUCTION It is well known that gold is associated with pyrite in most sulphide gold deposits and that the amount of gold associated with pyrite will vary from deposit to deposit. Most of the gold associated with pyrite is liberated in the grinding circuit during the processing of a gold ore. However, some gold remains occluded in the pyrite and is lost in the final leach tailings. Little information is available in the literature on methods to enhance gold liberation from pyrite by specifically removing pyrite, either in the grinding circuit or from the final tailings stream, and grinding it finer. One of the earliest record of this approach is described by King (King, 1949) where pyrite present in Witwatersrand gold ores was recovered by circular jigs and Johnson barrels followed by fine grinding of the concentrate prior to cyanide leaching. Dominy et al., 1970, provides information on the use of Yuba jigs to recover pyrite from the discharge end of ball mills. Again, the jig concentrate was ground to a fine particle size before cyanide leaching to recover the liberated gold. Unfortunately, no information is provided in these articles on the additional gold recovery from implementing these circuits in a flowsheet. Martins et al., 1993, provides details of a gravity circuit using Reichert cones and spirals to recover gold bearing pyrite from a cyanide leach tailings followed by fine grinding of the pyrite concentrate in a Tower mill. The ground concentrate returned to the front end of the already installed leach circuit. Overall recoveries were increased by some 2% to 4% depending on the amount of gold and pyrite in the plant feed."

Jan 1, 2017

By C. Horstmann, D. Andreo, G. Barthold

"The concept of large single line grinding circuits provides a valid answer in project feasibility studies by reducing capital investment requirements compared to parallel lines for the same plant throughput rates. The benefits of this concept are reflected as well on the operational aspects, in terms of higher and greater process stability, and reduced operational costs mainly due to the associated lower maintenance expenditures. However, concerns exist in the minerals industry on whether large single line grinding could reduce the overall concentrator plant availability. The mechanical design and integrity, the mill and gearless mill drive integration, as well as assets management aspects of this type of equipment are the key to guarantee successful availability records. Together with an overview of the added value provided by large single line grinding circuits, this paper focuses on risk mitigation strategies during mill and gearless mill drive integration, as well as on the design of the equipment itself, for the key aspects which could put at risk the operations availability.INTRODUCTIONDespite a large long term demand for commodities, the mining industry has never faced complex challenges as it is doing today. Decreasing high-quality and accessible deposits, declining ore grades in existing mines, shortages of electrical energy (e.g. in Chile) and an aging workforce are the most significant among the megatrends affecting our industry. In addition to this, flat underlying commodity prices and high price volatility are currently posing strong requirements to miners when entering into the process of approving investments.Nowadays to get projects financially approved (optimizations, expansions, new plants), capital expenditure has to be reduced, as observed up to 30% compared to the last decade, and at the same time the plant design has to be such to demonstrate that operating costs will also be significantly lower than in the past.When it comes to the concentrator plant, the concept of large single line grinding circuits provides a valid answer in project feasibility studies by significantly reducing the capital investment requirements compared to parallel lines for the same plant throughput rates. The benefits of this concept are reflected as well on the operational costs, in terms of higher and greater process stability and reduced maintenance expenditures."

Jan 1, 2016

By J. T. Liu, G. H. Han, W. C. Chai, Y. F. Huang

"In beneficiation process, metal ions could adsorb onto clay mineral surfaces or interact with flotation chemicals, and then result in the flotation behavior changing of desired minerals. Al(III) is the dominating ion existing in the bauxite flotation system. In this research, the adsorption behaviors of Al(III) on two silicate clay minerals (including bentonite and kaolin) were investigated by means of UV-Vis spectra, zeta potential testing and scanning electron micrograph analysis. The adsorption experiment results show that the adsorption capacity of clays for Al(III) ions increases with the initial Al(III) concentration, contact time and solution pH. There are some different adsorption behaviours for two clays. Increasing the clay concentration decreases the adsorption capacity of bentonite, while increases first then decreases for kaolin. Higher temperature favours the adsorption of Al(III) on bentonite but goes against for kaolin. The adsorption capacities of bentonite and kaolin for Al(III) respectively reach 12.48 and 0.875 mg/g at initial solution pH 5. Zeta potential results show that the adsorption of Al(III) on two clays is characterized by electrostatic attraction mechanism.INTRODUCTIONIn beneficiation process, there is inevitably a wide variety of metal ions generated from mineral crushing, mineral dissolution and water chemistry conditions. Metal ions adsorb on the mineral surfaces or interact with the beneficiation agents, affecting the flotation efficiency of desired minerals (DiFeo et al., 2001; Parolis et al., 2008; Shackleton et al., 2012; Shengo et al., 2014). Therefore, it is necessary to have a detailed investigation on the adsorption behaviour of metal ions on clay minerals.Having good ion exchange capacity and negative surface charge, the clay minerals could take up various metal ions from the mineral-water system. Bentonite and kaolin are very common aluminosilicate clays in the mineral processing system. These two clays both hold a permanent negative charge, =X- on the basal surfaces, and a smaller variable charge, =SiOH on the mineral edges (Gu & Evans, 2008; (Gu et al., 2010). Adsorption experiments are usually used to study the adsorption affinity of metal ions for clay minerals (Sen & Bhattacharyya, 2012). The adsorption of Zn(II), Cu(II) and Pb(II) onto natural bentonite showed that the adsorption amounts of metal ions increase with contact time, solution pH and metal ion concentration, but decreases with adsorbent concentration and system temperature (Sen & Gomez, 2011; Melichova & Hromada, 2013). Cr(III) adsorption on bentonite was significantly pH dependent. The adsorption process followed pseudo-second-order model and the equilibrium adsorption was consistent with Freundlich isotherm (Lollino et al., 2015). The adsorption behaviours of Pb(II), Cd(II), Ni(II) and Cu(II) onto kaolin indicated that increasing pH favoured the adsorption of metal ions (Jiang et al., 2010). The adsorption of Cd(II), Cu(II), Pb(II) and Zn(II) onto kaolin showed that an ion-exchange reaction occurred at pH<7.0 and inner-sphere surface complexes were prone to form at higher pH (Srivastava et al., 2005)."

Jan 1, 2016

By David G. Meadows

During the last decade Antofagasta Minerals? Los Pelambres Mine has dramatically increased its ore throughput following the fast initial phase ramp up through a series of planned incremental expansions. The original 85,000 mtpd, two SAG line plant was commissioned in 1999 and rapidly exceeded nameplate tonnage in only a few months. Following this, the inclusion of a pebble crushing circuit resulted in throughputs in excess of 114,000 mtpd and a recent, final third line SAG and ball mill addition have taken the plant to over 175,000 mtpd even with increasing ore hardness and changing ore feed characteristics. The progressive changes are described in this paper together with how the technical challenges have been met.

Jan 1, 2012

By R. Holmwood, M. Faris, P. Holloway, M. Collins

Sulphuric acid addition is a major driver of the economics in the processing of nickel laterite ores by high pressure acid leaching (HPAL). Understanding the optimal acid addition rate is essential for the success of any HPAL operation, and this is especially true at Ambatovy, where the composition of the feed tends to vary significantly on a day-to-day basis. Most studies on the effect of acid on nickel extraction in HPAL have used laboratory testwork as their basis. Although these studies are invaluable in assessing the economics of a new project, they are limited by the range of ore composition that can be tested and the differences between the operation of the laboratory equipment and the commercial plant. To enable optimization of the acid addition at Ambatovy, operating data from the HPAL operation were obtained using OSISoft’s PI system and the data from several periods were examined to develop relationships between acid addition and nickel extraction. The initial relationships from 2014 focused on the acid required to achieve a target nickel extraction of 95%, with aluminum and magnesium in ore and feed slurry solids content as the major variables. As Ambatovy ramped up through 2015 and 2016, the calculated acid requirement was further refined to address the effects of HPAL temperature and retention time, and the oxidizing/reducing characteristics of the ore, and to generate acid requirement relationships as a function of ranges of nickel extraction. These relationships supported raising the target nickel extraction to 96% and enabled the development of an economic model between acid addition and nickel extraction.

Jan 1, 2017

By M. E. D. Raymont

"During the history of the sulphur industry there have been three distinct phases of production. Factors controlling supplies during these periods have shifted from demand for sulphur to demand for energy and a cleaner environment. The pattern of brimstone production is t raced through these phases and includes estimates of future supply; these indicate an involuntary excess production of some 20 million plus tons per year by 1980 unless some large-scale new uses are found. Traditional uses for sulphur, including fertilizer, chemicals, fibers, etc., are generally expanding slowly; how• ever, supply in ""by-product"" form alone will soon outstrip demand. The predicted oversupply situation can be corrected by the development of novel potential markets. Promising areas include construction materials, insulation and plastics, among others."

Jan 1, 1972

By F. Sorenson, P. A. Castellarini, F. Garbarino, M. N. Garcia

"Recently, significant efforts to improve productivity from the tight intervals of the Mulichinco Formation within the Sierra Chata Field in the Neuquén Basin have been ongoing. Because conventional high quality reservoirs were being developed in this field, a proper reservoir understanding and completion approach was applied. After developing these high permeability reservoirs, the operator began evaluating the tight intervals and new areas within the field, but a completely different approach was necessary to achieve motivating production improvement.An extensive study to help enhance reservoir understanding and identify key factors controlling productivity of these tight intervals (which tend to be in the range of 5 µD) has been ongoing. Some of the issues discussed in this study are 1) petrophysical review, 2) rock properties calibration, 3) geomechanics understanding, 4) faulting and micro faulting/lineaments description, 5) stimulation and completions review and, 6) understanding key production drivers.As in many other tight reservoir projects, a considerable area of the reservoir must be effectively stimulated during the hydraulic fracturing process to achieve economic productivity. Two critical issues hinder these objectives. First, the low permeability in addition to a pore pressure close to or even lower than hydrostatic are critical characteristics when attempting to flow back the well and clean up fractures. Second, very high horizontal stress anisotropy resulting from a strike slip stress regime promotes the generation of simple planar bi-wing fractures. It is well-known that this fracture geometry will contact much less reservoir area compared to more complex fractures, as the operator would normally intend to create at very low permeability reservoirs.This paper discusses these issues and how they were addressed. A pilot drilling and completion program was initiated during 2012 to validate this study. Key factors include well location relative to formation unconformities, their orientation relative to the far field principal stresses, hydraulic fractures generated, and overall completion design."

Jan 1, 2015

By P. Condori

Palabora Mining Copper has a unique ore body composition which unlike other copper ore bodies has three main components in significant proportions; these are copper bearing ore, magnetite and dolerite. The high content of dolerite, a hard barren material, creates a high proportion of pebbles which normally are recycled back to the mill. This action increases the mill bearing pressure and power progressively until corrective actions are taken. A logical action to solve the pebbles generation would be to incorporate a pebble crusher. This in fact was done however two fundamental issues were encountered; the high content of magnetite and existence of a cyclone classification section. Due to the high content of magnetite, metal detectors have not been able to work efficiently to separate tramp metal which causes damage to the pebble crushers. The existence of cyclones in the circuit had a detrimental effect on the final product when the pebbles crusher was online producing coarse sandy material. Due to the difficulties in treating pebbles via conventional procedures and the unique Palabora ore composition and characteristics, sorting technology was investigated at laboratory and pilot scale. It was found that a combination of optical and electromagnetic sorting could efficiently separate dolerite from the copper bearing and magnetite ores. This paper reports the findings of the laboratory and pilot scale work performed and discusses the additional benefits to the circuit.

Jan 1, 2012

By J. A. Brusset

THE Greenhill mine of West Canadian Collieries, Limited, is situated at Blairmore, Alberta, and produces 2,500 tons per day of bituminous coal. On Monday, October 25th, 1943, smoke was discovered by a party of firebosses on their regular weekly inspection of air-ways. Probably the fire had been smouldering for several days but, as it had started on the outcrop at the top of an old raise filled with dirt, only a small quantity of smoke could filter through, and the plume of mist that crowns the fan at that season had prevented the fan-man from noticing it. This raise is only about 200 feet from the fan, and is 70 feet long between the fan-drift and the outcrop. It was impossible to prove the origin of the fire, as it had probably started several days before it was discovered, but it is possible that a careless smoker may have thrown a match into the opening at the outcrop, and that the old, dry timber had caught fire. The airways are in No. 2 seam, a bituminous seam 18 to 25 feet thick surmounted by shales and sandstones. Only 45 feet vertically above it is No. 1 seam, 12 feet thick, overlain by a strong conglomerate. In that vicinity, No. 1 seam had been worked out about ten years ago and the strata between the two seams are undoubtedly fissured. The pitch of both seams is 43 degrees.

Jan 1, 1945

By David Berberick

"Hecla Limited’s No. 4 Shaft at the Lucky Friday Mine is the largest capital expenditure in the corporation’s 128-year history and is considered the deepest shaft in the United States. This paper will discuss the project’s history and lessons learned from the initial conceptual design work in 2007 through project commissioning in 2017. Change management was key for the owner, contractors, and vendors in delivering the operational and organizational success on the project. The No. 4 Shaft has extended the life of the Lucky Friday Mine by 21 years to 2039. INTRODUCTION The Lucky Friday Mine of Hecla Mining Company (Figure 1) is the oldest active (77 years) and deepest mine in the Coeur d’Alene mining district, producing approximately 725 tonnes (800 tons) per day from narrow, vertical, silver, lead, and zinc veins. Primary access into the mine is via the Silver Shaft, a 5.5-m (18-ft) diameter, concrete lined shaft sunk to an original depth of 1,890-m (6,200-ft). Current production is from the Gold Hunter vein system, approximately 1,525-m (5,000-ft) northwest of the Silver Shaft.Cut and fill stoping is currently employed at depths to 2.3 km (7,500 ft) below ground surface, making it one of the deepest mines in the western hemisphere. No. 4 Shaft is a 5.5-metre (18-foot) diameter, concrete lined circular shaft, constructed as a 1.2 km (3,860 feet) deep winze in the Lucky Friday Mine. The 2.4 m (8 ft.) diameter, double drum, double clutch, Siemag hoist and associated headworks are situated at the 4760 level, top station at 4940 and shaft stations at 5900, 6500, 6580, 7500, 7580, 8300, 8380, 8500, and 8620. Shaft stations reference depth below Silver Shaft top station. The 4 Shaft was designed, constructed and commissioned over ten years, between 2007 and 2017. Basic design work was completed by Nordmin Engineering, followed by detailed design completed by Cementation Canada. Shaft construction was awarded to Cementation USA and lateral development was initiated in early 2008. Over the course of the next nine years, the project was suspended and restarted twice, dealt with the loss of a miner, added scope including shaft depth and mine infrastructure facilities, experienced squeezing ground that required liner replacement, changed excavation section, and dealt with a final alignment that was not within design requirement for verticality. Hecla and Cementation were successful in delivering a facility that provides fully functional access from collar at 4940 level to shaft bottom at the 8620 level. Two active mining levels below the collar, 5900 and 6500 are accessed. In addition, the shaft provides access to the future mining level at 7500, skip loading facility at 7580 level, station and loading pocket cutouts at 8300 and 8380 levels, spill pocket at 8500 level, and shaft bottom pumping facility at 8620 level (Figure 2)."

Jan 1, 2019

By D. E. Deegan, G. Holcroft, T. P. Johnson

"The rising cost of extracting metals from existing traditional deposits, increasingly stringent environmental regulations and a greater awareness of corporate social responsibility issues are all factors in stimulating the examination of mine tailings and small-scale alluvial deposits as a potential source of new raw materials. Furthermore, despite tougher economic times the demand for commodities remains strong, in no small part as a result of the growth of the world’s emerging economies.This combination of social and economic factors looks set to continue in the long term which will encourage greater recovery of materials from previously ignored sources such as mine tailings and ores from alluvial deposits.An expansion in the recovery of useful materials from mining-related activities is likely to require the use of robust and innovative techniques that have a built-in degree of future-proofing; DC plasma technology is one such technology.As a result of its ability to separate the valuable metal and minerals from the waste material while destroying hazardous compounds, Tetronics’ DC arc technology offers an alternative approach to resource recovery from a wide range of mine ores. Harmful cyanide compounds and the vast quantities of water used in conventional hydrometallurgical processing are avoided when plasma processing is adopted. DC arc technology also brings additional benefits, including: the extremely effective destruction of organic materials, the conversion of the inorganic material into a re-useable aggregate and the high tolerance of the process to fine and dusty materials. This paper presents details of Tetronics’ DC arc technology as one of the key pyro-metallurgical solutions available for the recovery of valuable materials from traditional mine ores and tailings, as well as giving specific examples of how the technology has been successfully employed in the recovery of enriched slags, ferroalloys and other metals."

Jan 1, 2016

By W. R. Tyson

Imperfections such as lack-of-fusion and undercut are inevitable in field welding of pipelines. Above a certain size, such defects must be removed or repaired. In the present state of the art, determination of allowable defect size is done by Engineering Critical Assessment (ECA). This requires measurement of toughness, and comparison of toughness with crack driving force. ECA methods used in current international pipeline standards will be reviewed and compared.

Jan 1, 2010

By Hulbert A. Lee

"A REVIEW OF MINERAL DISCOVERIES IN CANADA, and in particular the Canadian Shield, using the physical aspects of overburden reveals a trend in the art of exploration. At an early time of exploration (1847-1954), float and heavy clasts were used successfully to find ore deposits with little knowledge of Quaternary environments. At a later time (1955 to present) , use of Quaternary rock-units for sampling have made possible tracing indicator trains of float, heavy clasts and other ore-type clasts to the source bedrock. The basal till of retreat ice is now recognized as a1l favourable sampling environment and as such has been used to successfully discover hidden orebodies. The esker massive gravel is beginning to be recognized as a favourable environment and use of it has met with technical success. An understanding of those changes that have taken place during the transportation of the material and after its deposition is essential to proper sampling and treatment of the samples from the basal till and the esker massive gravel. Use of float and heavy clasts in search of orebodies is continuing in present-day exploration on the Shield. Lessons learned from it are being incorporated into exploration using favourable Quaternary rock-units for sampling. Hence, both subjects have a need for review and are discussed in this paper."

Jan 1, 1971

By Robin Sheremeta

Fording Greenhills first acquired GPS (Global Positioning System) technology with the commissioning of a GPS-based dispatch system in December 1994. The second exposure to satellite technology came with the conversion of the conventional optical survey system to a high-resolution GPS system in June 1995. In September 1995,a GPS-based grade control system was tested on the largest shovel (Marion 301 — 58 cubic yard).In January 1996, the system was added to all of the cable shovels (2 P&H 2800s). All three applications of GPS at Greenhills are fully operational and producing positive results. This paper will focus on the practical application of GPS in a mining environment and the effect that GPS technology has had on the Greenhills Mine.

Jan 1, 1996

By D. P. Ziegler

Formulas relating economic optimum busbar cross sectional areas to busbar cost, electric price and financial parameters are reviewed and revised. Application of the formulas is illustrated with discussion of the appropriate choice of parameter values and the sensitivity of the optimum to the parameters. The extension of the single busbar concept to optimization of more complicated arrangements of bus for smelting pots is complicated by the constraint of obtaining a specified current distribution. An example problem illustrates the optimization of a section of a bus network containing a fork, with the imposed limitation of achieving a specified uniformity in the current. In cases where the current in the individual conductors may vary, Kelvin&apos;s law does not apply. Further extension of the technique to a full pot set of conductors poses additional problems which are discussed, but whose solution has not yet been accomplished. Aluminium 2006 45th Annual Conference of Metallurgists ofCIM Montreal, Quebec, Canada Edited by

Jan 1, 2006

By T. W. Wlodek

"AbstractIn this paper a new type of durable 'spiral-rolled' drill set is introduced and its performance discussed. Efficient and economical mine drilling-depends to a great extent on durability of the drill-set employed. Premature failure of this element damages the drill bit and is costly when tungsten carbide bits are used.Time of drilling of 'spiral-rolled' drill sets introduced at present in Canada is considerably larger than for the presently used drill steel, but laboratory simulated service tests and practical field tests show that the 'drilling life' of the spiral-rolled drill set is several times that of ordinary drill steel.Some features of differential plastic deformation and differential surface rolling, so called 'spiral-rolling', are given.Relations between the drilling machine drill set and characteristics of the ore are discussed. The effect of shims on conical drill rod attachments, the mechanism of failure of drill steel, .and stresses during mine drilling, are analysed.IntroductionIN MINE DRILLING operations, the main interests are: the drilling machines as a source of working energy, the drill set as the tool transferring the working energy to the cutting edges of the bit, and, finally, the drilling characteristic of the .ore or waste rock.This paper includes a review of the possibilities of metallurgical and mechanical improvements in the drill set, with particular attention to drill steel and the attachments.For economical and efficient mine drilling operations, a durable drill rod, attachment, and drill bit are essential. Premature failure of any of these parts interferes with mining operations and is costly."

Jan 1, 1955