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By M. Maleki-Moghaddam

At the concentration plant of the Gol-E-Gohar Iron Ore Company (Iran) three 9 m × 2.05 m AG mills (fixed speed) are used in parallel in a dry operation. The performance of AG mills has been lower than the target value indicated by an increase in the product size (P80) from 450 µm (target) to 515 µm and low power draw (50% of nominal). By simulation it was found that increasing the liner lifter face angle from 7 to 30o while keeping the original lifter height (i.e., 22.5 cm) could provide an appropriate charge trajectory. When the proposed liners installed in one of the AG mills, the throughput increased by 27%; when 5% (v/v) balls were added the throughput increased by 40%. The product size also decreased from 515 to 501 µm.

Jan 1, 2012

By R. R. Bassermann

THE property of Howey Gold Mines, Limited is situated at Red Lake, Ontario, one hundred and seventy-five miles east of Winnipeg and eighty miles north of the Canadian National Railway line. The mine has been a continuous producer since April, 1930, and at present is hoisting 1,350 tons of ore per day. The shaft consists of three compartments (see Figure 1, sketch B). Hoisting is done by two skips in balance, one of which is interchangeable with a cage. Sinking had been carried out at three different periods. From the surface to the 550-foot level, the sets had been spaced at seven-foot intervals, from the 550-to the 1,060-foot level at six feet, and from the 1,060-to the 1,500-foot level at five feet. During the five years of operation, the shaft had become so badly worn, due to spill from the tipples and, to a certain extent, from the loading pockets, that re-timbering was considered necessary. It should be explained that no crushing is done underground because of the ad verse effect this would have on the efficiency of the sorting. The grizzly rail clearance above the ore pockets is fourteen inches and consequently the ore hoisted is extremely coarse. More than average spill from the loading pockets and tipples under such conditions is inevitable, and it is debatable whether underground crushing with consequent increased sorting costs would not be justified. The cost of complete re-timbering according to standard practice would have been prohibitive both directly and indirectly: A lengthy shut-down of the shaft, with the consequent disorganization of the staff and workmen, could not be considered. Accordingly, it became necessary to devise some method of repair that could be carried to completion in a very limited period of time. The shaft timber for the first 250 feet was not in need of repair. From the 250-foot to the 1,060-foot level the wall plates, posts, and blocking were in good condition. These had been protected by a one-inch plank lining put in at various periods during the past three years without interfering with hoisting operations. The end plates and dividers, however, could not be protected in this manner because of the lack of skip clearance. It was decided that, if the dividers in this section could be replaced, the shaft would be as satisfactory as if completely re-timbered. Several factors had to be taken into consideration in deciding on a suit-able method of repair. In the first place, the tipple plates had to be re-designed. To complete the job in a reasonable time, not only had work to be done on the tipple, but simultaneously from several points in the shaft itself. Since all power cables, pipe lines, etc., were in the manway compartment of the shaft, this compartment had to be left undisturbed.

Jan 1, 1935

By Ray Mason, Damien Label, Howard Bernier, Kevin McDermott, Kevin Coombs

"GeneralWabush Mines is an unincorporated joint venture of seven steel companies and Pickands Mather & Co. The mining and concentrating facilities are located in southwestern Labrador and the pelletizing and shiploading facilities are at Pointe Noire, 200 miles south, near the town of Sept-lies.The operation is based on a 5 ½ sq. mi. specular hematite deposit with a reserve of 375 million tons of concentrate. Annual production capacity is rated at 6 million tons of pellets per year. The final upgrading process utilizes high-tension separation of silica following wet autogenous grinding, spiral gravity separation and fluo-solids drying. The concentrate is railed in closed cars to Pointe Noire. The concentrate is reground dry and pelletized on Dravo Lurgi travelling grate machines to produce an oxide pellet with 65.5% Fe, 3.0% Si02, 1.95% Mn and 93.5% Tumble Index.HistoryPlant operations commenced in 1965 with a concentrator capacity of 5.3 million tons per year and a pelletizing capacity of 4.8 million tons per year. The original facilities for classifying the crude ore into fine and coarse fractions for storage purposes before reblending as autogenous mill feed were found to be unnecessary and were by-passed after plant startup. Capacity of the operation was increased to 6.0 million tons of pellets per year in 1968. This increased capacity required the installation of an additional160 cleaner spirals in the ore dressing plant, a new 5000 hp ball mill, three balling circuits and increased cooling air capacity in the pellet plant.In 1970, the regrind circuit in the pellet plant was converted to dry grinding and a significant reduction in grinding media consumption and maintenance costs was realized. A ninth grinding mill of 5000 hp capacity was installed to compensate for the reduced capacity in going from wet to dry grinding."

Jan 1, 2000

By O. K. Mahabadi, A. Lisjak, B. S. A. Tatone, N. Vlachopoulos

"Numerical simulations are widely adopted in the design of several types of rock structures, including tunnels, caverns, rock cuts, and open pit and underground mines. In recent years, analyses based on the hybrid finite-discrete element method (FDEM) have been shown to provide a realistic representation of rock mass deformation and fracturing processes. To date, the FDEM approach has successfully yielded qualitative and quantitative results for several practical rock engineering applications, yet it has lacked the ability to consider the implementation of rock-reinforcement measures. Since rock reinforcement is often used in civil and mining applications to improve the strength and deformational behaviour of a rock mass, the ability to incorporate such features into FDEM analyses is essential to extend its applicability to a broader range of problems. The work presented in this paper represents an important first step towards developing a simulation tool that can be used for practical rock engineering applications, including the design of underground excavations and rock slopes.INTRODUCTIONRock support and reinforcement measures are often employed in civil and mining rock engineering projects in order to maintain or improve the strength and deformational behaviour of rock masses. The preferred type of reinforcement or support elements along with the preferred layout and timing of installation depend on the in-situ ground conditions, the nature of the rock mass and excavation method. Over the last two decades, numerical modelling has been increasingly used to design and attempt to optimize rock reinforcement and support systems. As such, most rock engineering-specific modelling software now offers various approaches for modelling different rock reinforcement and support elements."

Jan 1, 2015

By R. J. T. Charles

Introduction An apparatus that will measure the surface area of a few of the simple minerals with a high degree of accuracy has been described by J. W. Bell (1). His apparatus consisted essentially of a photometric device that would measure the turbidity of fine particle suspensions. Turbidity, in this case, was considered as a function of surface area. Bell's method of surface area determination seemed to offer possibilities of extension and improvement to the point where it might approach a general method of particle size measurement. Theoretical and Practical Considerations of the Photometric Method In order to illustrate how turbidity may be considered as a function of average particle size, and to indicate the type of results expected from a photometric method of particle size measurement involving turbidity, the following theory may be hypothecated. If a number of particles, considered as spheres of uniform diameter, are placed at random in the path of a beam of light, the following expression, which will give the change in light intensity as a function of the diameter of the particles, the specific gravity of the material, and the weight involved, can be formulated from the Beer-Lambert Law:

Jan 1, 1951

By D. L. Morgan, J. A. Butterfield

"Geological data, production trends and current projects underway suggest that enough molybdenum will be available from more diversified sources to meet the world's growing demands. The growth in molybdenum consumption has been primarily related to its beneficial effects as an alloying agent in steel. This rapid growth has been deliberately fostered by stable prices, adequate supply and application research. The molybdenum industry is now in a process of change which has been seen in several other metals, such as aluminum and nickel. As supply sources have become more diversified, the market has become more competitive. The recent drop in consumption has led to excess production capacity, accumulation of substantial producer inventories and increased market uncertainties. While consumption is expected to increase in the next two to three years, it will take some time to absorb the excess capacity and inventory. The increased proportion of by-product capacity indicates that prices may become more variable. Producer discipline will be required to prevent serious price erosion in times of surplus. Future prices may not continue to increase with inflation. For the longer term, several factors favour the increased consumption of molybdenum. Engineering requirements are becoming more severe and molybdenum alloys can help to meet these changing needs. In addition, consumers can rely on a large and increasing supply of molybdenum. A 7 per cent growth rate in consumption can probably be sustained through the next decade, but new applications and reasonably stable prices will be needed to make this possible."

Jan 1, 1972

By O. A. Bascur

Several new hydrometallurgical plants have been built in the past years, new processes and equipment as well as advanced process control systems are being used to deal with the increasing requirements of safety, quality and production. Plant Information Management Systems are now being recognized as a key infrastructure component of the plant, giving the management, the operators, process engineers, finance, maintenance, and regulatory agencies an integrated view of the operation and providing the links for the (increasingly) multidisciplinary organization. This paper reviews several implementations of Plant Information Systems; real time performance management infrastructure examples are reviewed as a key component of business strategies, such as Mine to Port Planning and Supervision, Metallurgical Mass Balances, Solvent Extraction Composition Statistical Process Control, methods to minimize organic losses, reduce variable costs and to improve metal extraction. Several examples are provided to illustrate how companies are using the real time and historical information from assets and metallurgical processes to enable and empower people to improve the operations quality, safety and throughput, as well as continuous improvement and innovation initiatives.

Jan 1, 2007

By A. E. Flynn

Introduction The purpose of this paper is to record the results of researches on anhydrite that have been undertaken at the Nova Scotia Technical College during the last two or three years. The work was carried out in the Mining Department of the College, and several investigators were engaged on the work from time to time. Messrs. R. E. Hanson and K. M. Ed devoted their mining theses to the investigation, and Messrs. J. C. Hall and G. W. Baker were engaged on the work during the summers of 1928 and 1929, respectively. The writer was responsible for the initiation and direction of these researches, which were made possible by the financial assistance of the Department of Mines of the Province of Nova Scotia. Nova Scotia is the leading Province in Canada for gypsum production, its output being about a million tons per year, or over 80 percent of the production for the whole of Canada. The commanding position of Nova Scotia in this regard is due to the abundant supply of gypsum and its proximity to areas of intense utilization in the eastern United States. The resources of gypsum are contained in a total area of 627 square miles of gypsiferous rocks, so that an enormous reserve of this mineral is available. Present operations are confined to the highest grade and most easily worked deposits close to water transportation.

Jan 1, 1930

By Yujing Jiang, Xuezhen Wu, Bo Li, Tomomi Iura, Gang Wang

"Yielding bolt has been widely used for rock reinforcement in mining and civil engineering in high stress conditions. However, the interaction mechanism of yielding bolt and matrix mass is still not clear at present, and no analytical model is available to predict its reinforcement effect quantitatively. In this paper, the mainstream yielding rock bolts were reviewed firstly. After that, a coupling model is proposed to account for the interaction between yielding bolt and matrix mass. Based on the plane strain axial symmetry assumption and the incremental theory of plasticity, equilibrium equations and compatibility equations of matrix mass, and also the response of yielding rock bolt are deduced theoretically. The proposed method was programmed in Visual Basic development environment, and a semi-analytical solution for the coupling model is achieved. The reinforcement mechanism of yielding bolt in conventional tunnelling is clearly demonstrated through an illustrative case study. The reinforcement effect of yielding bolt is estimated quantitatively, and the distribution of axial force along the bolt is presented. In addition, the validity of proposed method is verified by numerical simulations. INTRODUCTIONHigh stress in surrounding rock mass can cause serious stability problems such as massive squeezing in soft rock and rock burst in hard rock. It is observed that many conventional rock bolts failed when experiencing large displacement, which implies that they are too stiff to sustain large deformation and dynamic conditions (Stillborg, 1994; Hoek et al., 1995). Yielding bolt, which can also be called energy-absorbing bolt, has been widely used for rock reinforcement in mining and civil engineering for these conditions (Neugebauer, E., 2008). This paper focuses on the static reinforcement effects of the yielding bolts with analytical method and numerical simulations."

Jan 1, 2015

By A. A. Iranzadeh

The performance of a tunnel boring machine (TBM) depends on the efficiency of the cutters, which can be influenced by geological conditions and rock mass properties. In this study, a three-dimensional numerical model, based on a discrete element method, was used to evaluate the effects of joint orientation and its spacing on the fragmentation process by a TBM cutter. Several models were constructed to study the effects of variable orientation; these models incorporated different spacing, variable spacing, different orientations on the fragmentation process, and different sections of the block model. Three parameters, consisting of induced tensile stress, induced shear stress and maximum displacement, were calculated. The stress in each section that forms chips was considered as critical stress; critical joint spacing and orientation in each section were determined. Results show that the critical orientation was in the range of 45 to 60º, where there was a possibility to achieve the maximum penetration rate. The critical joint spacing was 200 mm and, by increasing joint spacing, the value of critical stress decreased significantly. Furthermore, joint orientation could influence more than joint spacing in the rock cutting process.

Jan 1, 2009

By R. E. Whitehead, G. J. Prior

"Abstract -Biotite from aplite that appears to have crystallized simultaneously with disseminated Cu-Mo mineralization at MacLeod Lake in northern Quebec yields K-Ar dates in the range 2032 ± 44 Ma to '2f1:)1 ± 47 Ma. The mean value, 2065 Ma, is some 400 Ma younger than the 2485 ± 64 Ma date obtained from a hornblende concentrate separated from a granodiorite sill that is spatially, but apparently not genetically, associated with the disseminated Cu-Mo deposit. The mean biotite date of 2065 Ma at MacLeod Lake, a K-Ar date of 2055 Ma reported from an area 50 km east of MacLeod Lake and published dates of about 2000 Ma for galenas from the Chibougamau Cu-Au ores, suggest a widespread thermal and mineralization event, in that part of the Superior Province east of James Bay, that differs from the common late Archean mineralization that is related to volcanism and metamorphic-intrusive activity.Sommaire - Les datations au K-Ar sur des biotites qui auraient cristallisé en même temps que la minéralisation disséminée en Cu et Mo dans une aplite mise en place au Lac MacLeod, au nord du Québec, s'échalonnent entre 2032 ± 44 Ma et '2f1:)1 ± 47 Ma. La datation moyenne, soit 2065 Ma, est d'environ 400 Ma plus récente que la datation obtenue pour un concentré de hornblende extrait d'un fùon-couche de granodiorite qui est spatialement mais ne serait pas génétiquement as­ sociée à la minéralisation disséminée en Cu et Mo. La datation moyenne de la minéralisation au Lac MacLeod, soit 2065 Ma, la dataion au K-Ar à 2055 Ma citée pour une région à 50 km à l'est du Lac MacLeod, de même que les datations d'environ 2000 Ma établies pour des galènes qui se trouvent dans le minerai aurifère et cuprifère à Chibougamau, suggèrent un phénomène thermique répandu qui aurait produit la minéralisation dans cette région à l'est de la Baie James, dans la province du lac Supérieur. Ce phénomene serait différent de celui qui aurait produit la minéralisation répan­ due d'âge archéen tardif qui elle serait associée à l'activité volcanique et à l'activité intrusive accompagnée de métamorphisme."

Jan 1, 1992

By E P. Graham

Orebodies occur in an infinite variety of grades, shapes and sizes, and take many millions of years to grow. When extraction starts there is only one possible end -the mine sooner or later will run out of ore and shut down. If the mineral industry is to supply the ever increasing demands of modern civilizations, more and more metals must be found and mined. This will require a never-ending search for ore, and the development of every economic body, large or small. To justify the mining of a small orebody, it first of all must pay its way. If the size of the burden imposed by the capital cost estimates is not carefully worked out, an otherwise promising situation could be killed. The very nature of mining, as a transient industry, re-leases a steady stream of good used equipment, and the trained personnel to install and operate it. All manner of plans and layouts, which can be utilized at a new property, are available. Working these and other economies into the estimates will sometimes make enough difference to give a prospect the green light.

Jan 1, 1964

By Imane Benhamed, Jaouher Diouani, Laurent Cassayre, Florent Bourgeois, Carine Julcour-Lebigue, Université de Carthage

The attrition-leaching process aims at improving leaching performance when formation of passivation layers at the surface of leached particles is a severe limiting factor, as discussed recently by Julcour and coworkers (Julcour et al., 2015). This paper proposes a geochemistry-based modelling scheme for deriving the window of possible operating conditions for the attrition-leaching process to match the properties of the processed ore. The rationale is that the attrition-leaching process maintains the surface of reacting particles in an unpassivated state by continuous mechanical removal of surface leach layers, so that the process reactions can be modelled from thermodynamic equilibria throughout the duration of the process. The strength of the proposed modelling approach is that it bridges the gap between the properties of the ore and the process operating conditions. The present paper exemplifies the proposed process modelling route for derivation of the attrition-leaching process operating conditions in the context of the leaching of silicate ores, matching model predictions against controlled laboratory experiments. It is shown how thermodynamic modelling, when used in conjunction with a solid knowledge of the phases present in the system, can assist with deciding upon suitable process operating conditions. As an example, this firstprinciple modelling approach predicted that steel grinding medium would be converted into siderite (FeCO3) under a wide range of operating conditions, which led to questioning this initial choice of grinding medium for the attrition-leaching process under mineral carbonation conditions. It is emphasised that the same approach could be applied to ores of greater economic significance.

Jan 1, 2016

By Lachezar Tsotsorkov

Being a mining company, Assarel-Medet has a significant impact upon the environmental components. In order to meet the legal requirements and the requirements stipulated by the effective permits as well as to reduce the environmental imprint throughout the years, the policy of the company to implement a number of projects to improve the environmental components quality and the environmental state in the company?s region. The projects associated with atmospheric air quality management and reduction of the impact exercised by Assarel-Medet JSC by implementing various measures to eliminate the potential sources of the impact, preventive and rehabilitation initiatives as well as organizational and administrative activities are among the most important ones. A stable improvement of atmospheric air quality in the region and minimization of the company impact upon the ground air state in the region was observed in the period from 2005 to 2012 due to the applied measures. This project is a contribution to the environmental protection, in particular to atmospheric air protection, by applying integral monitoring and modeling methods to identify the negative impact by the mining companies and plan measures to reduce and restrict it as well as to improve the quality of the environment and living area of people working and living in the impact range as an element of sustainable development.

Aug 1, 2013

By M. Mirnezami, J. A. Finch

The McGill component of the consortium contributed detailed examination of the electrokinetic properties of the constituent minerals, primarily pentlandite and serpentine. Mineral specimens were derived from an ore sample; mineralogical examination showed the serpentine was predominantly clinochrysotile, a fibrous mineral responsible for much of the flotation separation problem. The study included design of a novel sedimentation potential measuring device to classify the surface charge of the ore and electrophoresis measurements on single and mixed minerals which progressively approached flotation conditions. The sedimentation potential measurements provided a general association between surface charge and the visual state of aggregation as a function of pH. The electrophoresis experiments started with single minerals in a background of indifferent electrolyte and progressed to mixed minerals in a background of supernatant derived from an ore sample. The single mineral tests supported the suspected electrostatic interaction, i.e., hetero-coagulation, at flotation pH 9-10. The mixed mineral tests demonstrated this interaction and also revealed hetero-coagulation with Mg(OH)2 precipitates, derived from the supernatant. This interpretation was confirmed by optical and electron beam imaging. A series of agents, CMC, polyphosphate, soda ash, EDTA, were examined to disperse the system. To accommodate the small mass of single mineral available a novel turbidity measurement using a UV/Vis spectrophotometer was introduced. Selected conditions were used in contact angle and small-scale flotation tests.

Jan 1, 2011

By R. Pressacco

"IntroductionAgrium’s history in fertilizer production and marketing goes back to 1931. Today, Agrium Inc. is a world leader in the production, distribution, and marketing of fertilizers and related products to the agricultural industry. Agrium is the largest North American producer of nitrogen fertilizers, a major producer of phosphate and potash fertilizers, and a world leader in fertilizer wholesale distribution and retail marketing. The mine at Kapuskasing is located some 40 km southwest of Kapuskasing, Ontario (Fig. 1). It has been developed to supply high-quality, low-cost phosphate rock to the company’s Redwater, Alberta facility, where it is an ingredient in ammonium phosphate fertilizer production. The Kapuskasing mine is the only phosphate mine in Canada and will rank as one of the highest-grade phosphate mines in the world (Clark and Duncan, 1999). Apatite is the principal ore mineral mined at the Kapuskasing Phosphate Operations.GeologyThe first record of exploration in the area was from a program executed by Continental Copper Mines in 1955 which evaluated the magnetic anomaly located in the Cargill and Cumming townships for its base metal potential. Intermittent exploration of the base metal potential of this magnetic anomaly continued in the following years, until the phosphate potential of the area was first examined in 1974 by International Minerals Corporation which recognized the presence of a layer of apatite sands overlying the carbonatite host rocks.The local geology consists of a core complex of multi-phased carbonatite rocks which are surrounded by a ring of pyroxenite, and have provided a U-Pb age date of 1907 Ma ± 4 (Sage, 1988). These two rock types are in turn situated within quartz diorite gneisses that form a large portion of the Kapuskasing Structural Zone (Fig. 2). The carbonatite host rock is sub-divided into two sub-types: sovite and rauhaugite. The sovite is a medium- to coarse-grained, white, banded rock in which calcite is the dominant carbonate species and it includes accessory minerals such as phlogopite, magnetite, clinohumite, apatite, olivine, pyrrhotite, and amphibole. Apatite can reach 15% abundance in this rock type (Sage, 1988). In sharp contrast to the sovite, the rauhaugite appears as a massive, fine-grained, dense, beige to tan-coloured rock in which dolomite is the dominant carbonate species. Phosphate values can range to 14% P2O5 in the rauhaugite."

Jan 1, 2001

By Leonard L. Fischman

It is important to define "adequacy," and the most useful definition is a continuing availability of mineral materials under cost and other conditions which imply no significant burden on the achievement of otherwise attainable levels of consumption and well-being. For current decision making, it is sufficient to consider adequacy just to the end of the century, with some regard being given to then remaining mineral inventory. A comparison of cumulative demand projections to the year 2000 with already identified reserves ( economically recoverable amounts in known deposits) suggests little reason for concern with world adequacy of iron ore, aluminum, manganese, chromium or potash. Conservative estimates of "prospective" reserves (amounts producible at today's prices, but yet to be discovered) suggests that there are ample quantities of virtually all other mineral resources as well. A probable exception is oil and gas, of which there may be scant amounts remaining after the turn of the century. However, there is an evident sufficiency of substitute forms of energy, though it is difficult to see just where developing technology will take us. The critical questions have to do with the increasing dependence of the industrialized countries on external sources of supply , coupled with a new international politic s which complicates the problem of insuring timely development of, and access to, remaining deposits. In this context, Canada, a still mineral-rich nation, is in one of the more favorable positions.

Jan 1, 1977

By Douglas H. Brown

Cadmium and other 'minor' metals in Canada tend to remain inconspicuous given the prominence of the country's massive production of other minerals. This same reality is reflected in the accuracy and deficiency of quantitative data concerning the sources of supply and demand for these metals. It is the intent of this paper to identify the nature of some of these difficulties and to reconstruct a more accurate description of Canada's production and consumption of cadmium, based on the results of recent surveys undertaken by the Mineral Policy Sector of Energy, Mines and Resources Canada and Noranda Sales Corporation Ltd.

Jan 1, 1978

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 R. D. Brown

"""A matter of serious concern to the mining industry in British Columbia""; this comment reflects the attitude of the Mining Association of British Columbia toward the proposed new B.C. Mineral Royalties Act. The proposed legislation, introduced by the provincial government in February and now being debated by the legislature, combines a basic 5% royalty on the selling price, less approved p1ocessing and transpo1•tation costs, of minerals produced in B.C. with an ""excess"" royalty of 50% of any price increases over a predetetmined base. Government estimates project annual revenues of $20 million from the new royalty structure. The accuracy of these figures has been contested by the mining industry. Based on current world prices for copper the industry estimates that the provincial revenues from this mineral alone may run as high as $140 million in 1974 and $150 million in 1975. The Mining Association has warned that the new royalties “threaten to become confiscatory""."

Jan 1, 1974