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By Enrique Rubio

Several mining operations are currently evaluating the feasibility of changing their mining method to Block Caving. There will also be several deep low-grade ore bodies that will face the need to go underground in following their ore to depth. There are two main reasons why Block Caving is attractive: firstly, it offers the lowest operating costs amongst all the mining methods; and secondly, it is truly a massive mining method, offering the highest potential production capacity. Despite its longstanding popularity, there are still significant components of the method that are not clearly understood. Also, the lack of availability of key geomechanic information still presents a major obstacle to developing mine planning and production scheduling. There are several key issues in block caving that can make it feasible such as cavability, fragmentation, stresses will condition the way that a block caves and the way that material is drawn from the draw points. Consequently Block Cave mining method is a good example where the ore body has to be related to design and mine planning. The concepts of dilution, draw control as well as sequence definition are reviewed in this paper to illustrate the idea of integration. There have been some examples of mines where some of the components of mine planning have not been integrated causing a disaster in terms of economics or safety. Different layouts configurations might give a different result in the planning of the mine

May 1, 2002

By E. Busse, J. E. Burgener, J. G. Eacott, M. C. Robinson, P. E. Burgener

"This paper presents a preliminary assessment of the technical and economic feasibility of a caustic leach - electrowinning process for the recovery of zinc and lead from electric arc furnace baghouse dust at a mini-steelplant. Recent studies and literature are referenced briefly as they pertain to the formation and characterization of dust, toxicity considerations and alternative dust treatment and disposal options.Laboratory testwork results, published data, pilot plant experience and anticipated influences resulting from recycling residues are used for the purpose of developing a conceptual design for a caustic leach - electrowinning plant to treat 15,000 tonnes/year of dust at a one million tonnes /year capacity steelplant in Canada.Target economic studies, comprising preliminary estimates of capital and operating costs, revenues and rate of return are presented. Economic and commercial considerations concerning the relative merits of dust treatment at a centralized facility compared with an on-site plant are discussed.IntroductionThe treatment or disposal of mini-steelplant electric arc furnace (EAF) baghouse dust has been given increasing attention in recent years for two principal reasons. Firstly, the dust is now classed as a hazardous waste material under V.S. EPA regulations which prohibit its disposal in dumps other than controlled landfill sites. Secondly, the dust contains certain metal values, notably zinc and lead, which may be economically recoverable, depending on the costs associated with disposal resulting from enforcement of the EPA regulations. Other metallurgical dusts and waste materials, from both ferrous and non-ferrous operations, may require the same considerations as EAF baghouse dust.Several studies have been carried out to examine various aspects of dust treatment but few commercial plants are in operation. Technology employed uses pyrometallurgical techniques. Commercial-scale hydrometallurgical plants are not known to exist although small-scale plants are frequently more economically attractive than their pyrometallurgical counterparts which generally require economies of scale to be viable.The concentration of mini-steelplants in northeast V.S.A. and southeast Canada merits study to determine whether or not dust treatment for metals recovery is a commercially feasible alternative to disposal.This paper examines the technical and economic feasibility of a caustic leach - electrowinning process for the recovery of zinc and lead from EAF baghouse dust at an on-site ministeel plant processing carbon steel scrap and discusses economic and commercial considerations pertaining to dust treatment at a larger, centralized facility."

Jan 1, 1984

By G. E. Norman, R. E. Michelutti

"One of the major objectives of Falconbridge has been and continues to be, to minimize the impact of its operations on the environment around its Sudbury operations.The approach to achieving this objective and the results, are discussed under the following topics .I . Sulphur Dioxide Emission Improvements.2. Effluent Treatment Improvements .3. Effect of the Envrionmental Improvements.Sulphur Dioxide Emission ImprovementsHistoryThe rejection of pyrrhotite in the concentrators is one method of reducing the amount of sulphur to the smelter and therefore the sulphur dioxide emissions. In the 1950s and 1960s, Falconbridge developed the capability to remove 54% of this pyrrhotite. Numerous attempts were made to increase this amount by treating the pyrrhotite for recovery of nickel and in some cases elemental sulphur. Processes tested and operated were: hydrometallurgical pilot plant, roast-leach commercial operation and nickel-iron refinery. None of these processes proved to be commerically successful for both technical and economic reasons. Falconbridge therefore redirected its efforts to reducing sulphur emissions by improving its smelting process under The Smelter Environmental Improvement Project. A major component of this project was the installation of a sulphuric acid plant to recover the S02 in the roaster off-gases."

Jan 1, 1984

By M. J. Medd, G. A. Speirs

"This paper describes the simultaneous sinking and equipping of a 4.9 m diameter concrete-lined shaft to a projected depth of 1660 m. The shaft blast design utilizes the full face method using a parallel hole burn cut. Hydraulic drilling and a totally redesigned Cryderman-type mucking unit were integrated into the four deck sinking stage to provide for drilling, mucking, concreting and shaft steel equipping operations. A safety program was tailored and implemented specifically for this shaft sinking project.IntroductionIn July 1988, Falconbridge Limited commenced development of its Thayer Lindsley exploration site located some four km north of Sudbury on Regional Road 80.The first phase of this project was awarded to J .S. Redpath Mining Consultants Limited and the scope of work included the engineering and project management to construct a surface plant capable of supporting a shaft sinking and exploration program for potential future mine development. This initial phase of the project was completed on schedule and under budget on December 23, 1988, and is the subject of an independent paper.In November 1988, J.S. Redpath Limited was awarded the shaft sinking and exploration phase of this project. The scope of work consisted of sinking and equipping a 4.9 m diameter shaft to a depth of 1660 m and carrying out the development and diamond drilling on two levels. This work was scheduled to be completed by November 1991.The T .L. Exploration Project is located toward the eastern end of the south range of the Sudbury basin, north of Sudbury. Figure 1 details the projected mining area and the shaft location on the geological complex. Figure 2 is a section showing the exploration shaft that is located in the Norite. Two levels will be developed from this shaft, on the 1310m and 1588 m levels, to provide access for further geological examination of the ore bodies."

Jan 1, 1991

By David A. Fawcett

"This paper presents a summary compilation of current Canadian coal research projects in the areas of exploration, mining and preparation. The compilation forms the basis for a review of present operations and technology, and of current research efforts. General research areas, requirements and priorities are suggested along with a discussion on achieving the research goals in terms of funds, facilities and staff. The current level of research funding in these areas is assessed. IntroductionCanada's coal production is expected to undergo major expansion over the next two decades in response to domestic demands on coal for electrical power generation, industrial uses and conversion to synthetic .fuels, and in response to export demands for both thermal and metallurgical coal s. Surface mining will continue to dominate, but underground mining will contribute an increasing proportion to total production.In Canada, coal research, particularly in the areas of exploration, mining and preparation (E, M & P), has been limited. Increased impetus has recently been given to this research with expansion of CANMET's activities and with the establishment of the Coal Mining Research Centre (CMRC). University researchers are branching into coal research; strata mechanics and preparation are popular in mining-related fields.With the increase in number of organizations and individuals involved in coal research, a means of keeping abreast of the ongoing work is necessary. An annual summary of the status of and developments in current research assists in providing this information. The CMRC prepared such a summary for Canadian coal E, M & P research in 1979 and it received favourable response, justifying the effort. A 1980compilation has been prepared and pro vides the basis for this paper; it is presented with a brief discussion on background, format and content.The compilation forms a basis for an examination of the current status of Canadian technology in E, M & P and of the ongoing research in each area. General research requirements are reviewed and programs and tasks are suggested, followed by a discussion of research goals in term s of priorities and achievement. An assessment is made of the level of research funding in Canada, with comparisons drawn from the United States, the United Kingdom and Australia."

Jan 1, 1980

By J .. R. Brown, G. Deschenes

X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction (XRD) and Electron Probe Micro-Analysis (EPMA) were used to characterize chemically the gold complex adsorbed on activatedcarbon from a solution containing 102mglL Au and 0.5 giL thiourea. This paper also considers the gold chloride and the gold cyanide systems. The results indicate gold is adsorbed on activated carbon from the thiourea solution as the gold (I) thiourea complex, i.e. Au [CS (NH) 2];' Other gold species such as metallic gold were not detected on the carbon support. These results also suggest the elution of the gold (I) thiourea complex can be performed with high recovery.

Jan 1, 1993

By J. R. Pronovost, P. M. Tiley, D. W. Watts

"In 1980, J.S. Redpath Limited were retained by Dickenson Mines Limited to increase hoisting capacity from 700 to 1000 tons per day. The hoisting capacity of the present skip-over-cage system could not be increased significantly through design modifications. The other constraint was a minimum of disruption to the current production. The Dickenson shaft was a three-compartment shaft from surface to the 8th level and four compartments before the 8th to the 23rd level. The solution to the problem was to remove the services from the shaft man-way compartment from the 8th level to surf ace by drilling a borehole close to the shaft and rerouting those services through the borehole to the 8th level. A service compartment would then be available from surf ace to the 23rd level.By providing a service hoist in this compartment, the skip hoist would then be free to produce the 1000-tons/day required production. This paper will describe the search for the required hoist and the friction hoist selected for the project, and trace the design modifications required to modify the hoist to suit the Dickenson application and satisfy the Department of Labour safety requirements.The paper has been co-authored by J.S. Redpath Limited and C.L. Tiley Associates, who participated in the design changes and eventual commissioning of the hoist.IntroductionIn the earl y part of 1980, J.S. Redpath Limited conducted an engineering study on the Dickenson Mines Limited No. 1 Shaft materials handling system. The object of the engineering study was to investigate the possibility of increasing the tonnage hoisted from the No. 1 Shaft complex by adding a service cage compartment and service hoist. This would permit utilization of the existing hoisting plant solely for production hoi sting. A further consideration of the engineering study was that any alterations had to be accomplished with little, or no, interruption to production."

Jan 1, 1982

By J. R. Pronovost, P. M. Tiley, D. W. Watts

"In 1980, J.S. Redpath Limited were retained by Dickenson Mines Limited to increase hoisting capacity from 700 to 1000 tons per day. The hoisting capacity of the present skip-over-cage system could not be increased significantly through design modifications. The other constraint was a minimum of disruption to the current production. The Dickenson shaft was a three-compartment shaft from surface to the 8th level and four compartments before the 8th to the 23rd level. The solution to the problem was to remove the services from the shaft man-way compartment from the 8th level to surf ace by drilling a borehole close to the shaft and rerouting those services through the borehole to the 8th level. A service compartment would then be available from surf ace to the 23rd level.By providing a service hoist in this compartment, the skip hoist would then be free to produce the 1000-tons/day required production. This paper will describe the search for the required hoist and the friction hoist selected for the project, and trace the design modifications required to modify the hoist to suit the Dickenson application and satisfy the Department of Labour safety requirements.The paper has been co-authored by J.S. Redpath Limited and C.L. Tiley Associates, who participated in the design changes and eventual commissioning of the hoist.IntroductionIn the earl y part of 1980, J.S. Redpath Limited conducted an engineering study on the Dickenson Mines Limited No. 1 Shaft materials handling system. The object of the engineering study was to investigate the possibility of increasing the tonnage hoisted from the No. 1 Shaft complex by adding a service cage compartment and service hoist. This would permit utilization of the existing hoisting plant solely for production hoi sting. A further consideration of the engineering study was that any alterations had to be accomplished with little, or no, interruption to production."

Jan 1, 1982

By Per-Lennart Nystedt

"The Boliden Lead Kaldo Plant for the treatment of lead bearing flue-dust from the Copper Smelter and the Slag Fuming Plant has been in operation at the Ronnskar Works of Boliden Metall since the middle of 1976. At the present stage, the plant can treat lead-bearing dust of different kinds and compositions. The process allows good separation of arsenic and halogens from lead.The flue dust from the Copper Smelter and the Slag Fuming Plant is very complex and, apart from lead, also contains zinc, copper, tin, bismuth, cadmium, antimony, arsenic, sulphur, silver, chlorine and fluorine. The metallurgical process has been developed by Boliden Metall and has been tested on a pilot scale at the Foundation for Metallurgical Research (MEFOS) in Lulea, Sweden.The pelletized dust is smelted in the converter, where the heat is generated by an oil oxygen burner. The second step consists of reduction with coke. A lead bullion and slag are obtained. The slag, transported in liquid form, is treated in the Slag Fuming Plant for the recovery of zinc. The third step is the elimination of arsenic from the bullion. This is achieved by treating the lead with iron (turnings or pellets). The result is a crude lead and speiss. The lead contains silver, tin, antimony and bismuth, and is suitable for the final refining stages in normal plant equipment for refined lead.For process control, we use the rapid analysis centre, which is pneumatically and electronically linked to 'all major plant sections and allows for a quick turn-around between delivery of the sample and feedback of results. All three steps in the process are performed in the same converter.Since the starting up of the plant, the original process has been subjected to some modifications. Initial problems related to equipment, maintenance and environment have been solved step by step. Examples are quoted. Recent operating particulars are presented."

Jan 1, 1980

By R. C. Carne, R. J. Cathro

"Most of the recent large discoveries of zinc, lead and silver in Western Canada are Paleozoic-aged stratiform deposits that occur within the limits of the tectonic sub-province of the Canadian Cordillera known as Selwyn Basin. Bounded on either side by coeval carbonate platforms. Selwyn Basin trends northwest for 1300 km from northeast British Columbia to Alaska. Paleozoic rocks of Selwyn Basin consist primarily of chert, shale and coarser-grained clastic sedimentary rocks with minor volcanic rocks.The Selwyn Basin deposits have few counterparts elsewhere in Canada, but have a close similarity in geological setting, mineralogy and morphology to well-known deposits such as McArthur (HYC) in Australia, Meggen and Rammelsberg in West Germany, and Sullivan in British Columbia. Recent studies of these deposits have led to an emerging, but now generally accepted, model of ore deposition in which stratabound zinc-lead-silver shale-hosted or ""sedimentary-exhalative"" (sedex) deposits are precipitated in active tectonic environments from metalliferous geothermal brines that rise to the sea floor along deep-seated fault zones. Although their mineralogy and ore metal zoning can be similar to that of volcanogenic massive sulphide deposits, most sedex deposits have only a weak genetic link with volcanism.Sedex mineralization in Selwyn Basin has been identified within three separate ages of shale or its metamorphosed equivalent. The lower Cambrian-age Anvil Camp in central Yukon Territory contains the only producing mine (Faro). Important lower Silurian-age zinc-lead mineralization is at Howards Pass along the Yukon - Northwest Territories border. Barite and zinc-lead-barite mineralization of upper Devonian age occurs across Selwyn Basin. Potentially economic deposits have been found at Macmillan Pass, along the Yukon - Northwest Territories border and in the Gataga District of northeastern British Columbia."

Jan 1, 1982

By E. Wright

"INTRODUCTIONThe Ruttan Mine is located twenty-two km east of Leaf Rapids in northwestern Manitoba. The copper-zinc exhalative massive sulphide deposit is comprised of a series of individual and interconnected en echelon lenses which strike east 20 degrees north and dip south 70 degrees. The mine has been owned and operated by the Hudson Bay Mining & Smelting Company since July 1987. Sherritt Gordon Mines Limited began mining the orebody in 1973 from an open pit, but production has been entirely from underground since 1980. HistoryDuring the progression from open pit to underground mining, it was recognized that manual methods of ore reserve calculation were inadequate for responding to changing metal prices and evaluating alternative mine plans. The mine planning system that was developed is described in the paper, ""Computerization of Ore Reserves and Mine Planning Functions at Ruttan Mine"", presented by B.C.W. Haystead at the 1984CIM Annual General Meeting. At that time, programs for core logging, diamond drill hole plotting, grade interpolation, ore outline digitizing, and reporting had been developed by the Systems Department for use on Sherritt's UNIVAC 1100 mainframe computer. Telecommunications linked terminals at the Ruttan coreshack and office to the UNIVAC in Fort Saskatchewan, Alberta. The same mine planning system was also used at a second property.Operation of the mine planning system was expensive, and it was evident that increased use required a costly upgrading of the UNIVAC in order to maintain an acceptable service level to all users. The system was re-evaluated,' and it was concluded that: core logging was not easily adaptable to a new property, nor flexible enough for exploration; plotting, grade interpolation, and digitizing required considerable manual effort; and that the UNIVAC operating system was difficult to learn.It was recommended that a study should determine if: core logging could be redesigned and/or implemented on a microcomputer; interactive graphics be used to reduce the effort for functions requiring visual interpretation; and the creation of input processors would assist users in setting up parameters for guiding the programs."

Jan 1, 1989

By H. W. King

"Cryogenic engineering is concerned with components and machines which operate for long periods of time at temperatures within a few degrees of absolute zero. The absence of a ductile-brittle transition is thus the prime component of the specification for a suitable low-temperature alloy. The word "" cryo"" means ""frost-forming"" , and this leads to the second component of the alloy specification, which is resistance to corrosion in humid atmospheres. Further, although most early applications of low-temperature alloys were limited to the storage or transportation of liquified gases, an increasing proportion of alternative energy storage and conversion technologies are being based on the availability of high-field superconducting solenoids. The third basic component of the specification for a low-temperature alloy is thus the absence of a low-temperature ferromagnetic transition.Although the firs t two of these components of the specification can be met by using austenitic stainless steels, many of these supposedly "" non-magnetic"" alloys have been found to undergo martensitic transformations to ferromagnetic phases at very low temperatures. In addition, steels which remain structurally stable may still exhibit other magnetic transitions, e.g. to antiferromagnetic or superparamagnetic states. The successful application of these alloys in cryogenic engineering has thus required an initial basic study of the types of magnetic transition that can occur in such concentrated solid solutions, followed by a more applied study directed at an alloy formulation which will induce beneficial magnetic states at low temperatures."

Jan 1, 1981

By Roger J. Goodman, Don Riva

"IntroductionCrows Nest Resources Limited (CNRL), a wholly-owned subsidiary of Shell Canada Resources Limited, is nearing completion of its first coal project, located in southeastern British Columbia. CNRL shipped over 700,000 tonnes of thermal coal to foreign markets in 1982. With the completion of the metallurgical coal plant in December, 1982, shipments of both thermal and metallurgical coal will increase substantially in 1983 and will approach the anticipated operating capacity of 3.0 million tonnes in 1985. The Line Creek Mine lies some 25 kilometres north of Sparwood in southeast British Columbia (Fig. 1). The open-pit mine is located on top of Line Creek Ridge, with coal being hauled 16 km to the thermal and metallurgical coal preparation plants, situated adjacent to the already existing Canadian Pacific Railway. Most of the coal is moved by 108 car unit trains by CP Rail to coal ports in Vancouver, where it is loaded onto vessels destined for overseas markets. Some smaller scale car load shipments are moved by rail to contiguous markets in the Pacific Northwest. History The southeastern British Columbia area, known as the East Kootenays, is steeped in a rich coal mining heritage, dating back to the latter part of the nineteenth century. Predecessors of Crows Nest Resources Limited were instrumental in developing the rich coal reserves in the area. In 1887, William Fernie, a pioneer-cum-prospector recognized the potential of coal deposits in the East Kootenays. Spurred by the relentless push west of the Canadian Pacific Railway through the Crows Nest Pass area, Fernie recognized that it was just a matter of time before the steam locomotives provided him with his required market. That time arrived in 1897 when Fernie helped to form the Crows Nest Pass Coal Company and coal mining commenced at Coal Creek, near his namesake town of Fernie. During its almost 70-year history, this company produced over 48 million tonnes of steam coal and 8 million tonnes of coking coal. In 1965, the Crows Nest Pass Coal Company was re-named Crows Nest Industries, to better reflect its expanded interests into forest products, and it is the latter company which Shell Canada Resources Limited acquired in 1978. The extensive coal resources of Shell, in both Alberta and British Columbia, were rationalized into one group with the birth of Crows Nest Resources Limited to manage and develop the coal holdings."

Jan 1, 1985

By C. J. Newman, D. J. Kemp, R. M. Sweetin

"The smelter is described by area; feed preparation, continuous furnace line, gas handling and auxiliary systems, blister refining, Hazelett casting of thin anodes, and scrap remelting. Early smelter campaign data is presented and compared to design. Some modifications to the basic design of the furnaces and gas trains are indicated, with their respective impacts on improving smelter performance.Plant compactness, the use of jumbo tanks, and a highly automated electrode handling system are featured in the refinery description, with brief coverage of the liberator and slimes leaching sections. Early experience in refining thin regular Hazelett anodes, and submersible pump recovery of raw slimes are relayed, together with automatic stripping from titanium blanks.Refinery tonnages and operating parameters are given showing the relatively trouble-free attainment of refinery design performance.IntroductionPrevious papers and articles ( 1), (2) ,(3 ) have described the metallurgical facilities serving the copper-zinc-silver Kidd Creek orebody located near Timmins, Ontario. For convenience a brief review of their mid-1983 operating status is presented.The concentrator, originally designed for 9,000 short tons, was commissioned in late 1966. It can now comfortably process over 13,000 metric tonnes per day largely as a result of the addition of a fourth circuit in 1978."

Jan 1, 1984

By W. L. Stuewe

For the purpose of this paper I shall, in order to limit myself, define the words 'Maintenance' and 'Equipment' as follows: Maintenance shall mean the 'care of or 'the sustaining of equipment in as nearly perfect condition as possible. Equipment shall mean any item of a mechanical nature entering into the production of coal; it will be seen that unless one limits the use of this word it could take in administration as well as operative equipment, and include metal mines, mills and smelters, and manufacturing plants. In any industry the first consideration is the proper operation of all units entering into the production of the article manufactured or produced. I wish to quote here what a man, well known internationally in financial circles, told his operators at the time a large expansion programme was under consideration. His exact words were: "I do not care how much it is going to cost. What I want to know is how much it is going to cost to operate and maintain. It is the continuous drain for repairs that costs us the most money." The truth of this statement has been proved time and again, and many companies have found the cost of maintenance to be the balance between profit and loss-so much so that, in two instances with which the writer is familiar, the mechanical equipment was practically replaced throughout. I bring this point out here to emphasize the value and necessity of keeping abreast of the times, and obtaining maximum efficiency with the minimum outlay. Time is indeed money where delays occur due to defective or poorly kept equipment, and it is absolutely necessary to prevent machinery from becoming defective or inefficient.

Jan 1, 1930

By John D. Smith, Robert J. Mitchell

"There is a world-wide trend toward underground bulk mining methods employing hydraulically placed backfill. This trend is recent and therefore there is little in the literature to assist an operator in the design of backfill properties, the design of drainage facilities, the calculation of the operating forces on a bulkhead, and the control procedures considered necessary before, during and after pouring. This paper presents recommended procedures that are based on over to years of experience in the various aspects of backfilling large openings. Free-draining timber or concrete block bulkheads are shown to be a viable alternative to massive reinforced concrete bulkheads for the containment of backfill pours. Hydrostatic pressures cannot develop in backfills provided adquate drainage facilities are installed.IntroductionThe increasingly adverse relationship between mining costs and mineral values has led mining companies to develop more productive, lower-cost, bulk mining methods. This has led to the increasing use of large, more or less continuous, hydraulically placed backfill pours to enable the recovery of a higher proportion of pillar ore. The success of any bulk mining method depends on the degree of stability maintained during the stoping operations with reference to the mining rate, the performance of the backfill with respect to the per cent extraction of pillar ore, and the control of the mine structure with respect to safety and productivity. One such method has been previously described(I) where a steeply dipping orebody is being mined with a sub-level method that employs large, hydraulically placed tailings pours for delayed pillar recovery. The paper describes the rock mechanics analysis undertaken to establish the stope and pillar geometry and the approach taken to establish backfill strength requirements to prevent dilution during pillar recovery. Production with this method started in 1970 and because few, if any, large bulk pours had previously been used in- this way (judging by the lack of information in the literature), design data and criteria were needed for several aspects of the work. Methods to establish backfill quantities and pertinent ""in-place"" fill properties are described in 2, 3 and 4 in the list of references. Results of field measurements taken to establish fill pressures for bulkhead design purposes are described in 5 and 6. Laboratory large-scale model tests undertaken to confirm a fill strength design equation, which takes into account fill arching, have recently been completed. A paper describing these tests and the results will be forthcoming in the near future."

Jan 1, 1982

By Gary M. Poxleitner

Skip/Hoist ?Vertical Advantage of Hoist ?High capital ?High operating cost Trucks Trucks ?Flexibility of ramp ?Low capital ?High operating cost Conveyor Inclined High capital ?Low Cost to run ?Continuous Production ?High Capacity ?Transfer pointsMax Grade: +32%

Feb 1, 2008

By R. D. Brown

"An adequate level of R & 0 is crucial to achieve gains in productivity and to strengthen Canada' s position in an increasingly competitive world ." So stated Finance Minister Jean Chretien in his April 10, 1978 budget speech, on announcing a new measure designed to increase the productivity of Canadian industry and to assist in the creation of new technology. The effect of the new measure, which permits an income tax deduction of 150% of certain research and development (R & D ) expenditures , can reduce the after-tax cost of a marginal dollar 's worth of such expenditures to as little as 20 cents . This article discusses the income tax treatment of R& D expenditures in general, and describes in particular the income tax incentives which relate to R& D.

Jan 1, 1978

Cominco began investigations about ten years ago relative to noise abatement in underground operations. As a result of intensive research, this study has advanced so that the practice now has wide application. Automotive mufflers are used on vane-type blasthole diamond drills. Exhaust hoses are attached to longhole percussion drills. Hand-held drills, such as airlegs and stopers, are equipped with mufflers which are either part of the drill, as received from the manufacturer, or are light rubber de-vices developed, fabricated and installed by Cominco. Ear defenders are in general use. The paper reviews details of practices employed, and assesses the success achieved. Noise is generally associated with some of the basic equipment used in mining. About ten years ago, in order to improve on this situation. The Consolidated Mining and Smelting Company of Canada Limited began investigations relative to noise abatement in its underground operations. As a result of intensive research, this study has advanced to the point

Jan 1, 1964

By P. R. Goad

"Kidd Creek is a large volcanogenic base metal sulphide deposit, located near the west end of the Abitibi greenstone belt, 27 km north of Timmins, Ontario. The rhyolite geology is characterized by a NNE-striking and steeply east-dipping package of rhyolite volcaniclastics upon which has been imposed a strong ESE-striking and north-dipping structural fabric . Massive rhyolite units with grey-black. chloritic cores and yellow, sericitic margins intrude as dykes into the stratigraphic footwall and as sills higher in the stratigraphy. Massive rhyolite units positioned near the top of the felsic pile exhibit an extensive marginal development of hydraulic fracturing and are termed crackle-brecciated rhyolite.The stringer sulphide zone is positioned in a lobate blanket of crackle-brecciated rhyolite at the top of the felsic pile. The stringer sulphide zone is characterized by a mature chemical alteration, being specifically depleted in alkalis and enriched in iron-rich chlorite. with accompanying silica, sericite and carbonate alteration. A suite of trace elements characterizes this mature alteration. The massive rhyolite units, which intrude lower in the rhyolite volcaniclastics, exhibit a core of weak chlorite alteration and strong marginal sericite alteration. Tight or unfractured massive rhyolite units are essentially devoid of sulphide mineralization and exhibit a suite of trace elements characteristic of this immature alteration. It is interpreted that the massive rhyolite units intruded into an already evolving system and ""choked-off"" active conduits carrying hydrothermal fluids and subsequently acquired an immature alteration signature. Rhyolite units positioned higher in the pile developed intense hydraulic fracturing and a mature alteration coincident with the formation of the stringer sulphide zone. In summary, a model, based strictly upon the rhyolite geology, is reviewed to assist in the exploration for volcanogenic base metal sulphide deposits."

Jan 1, 1985