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By J. A. Eisele, D. L. Pool

"The Bureau of Mines has developed a particle agglomeration technique to improve the flow of leaching solution through heaps of low-grade gold-silver ores which contain clays. Benchscale experiments and industrial practice have shown that the percolation rate of cyanide leaching solution is greatly enhanced by mixing the ore with Portland cement as a binder, moistening the mixture, mechanically tumbling to form agglomerates, and aging before heap building and leaching. A slight modification ofthe technique allows its application to precious-metal-bearing tailings, which cannot normally be treated by heap leaching because they are too fine. IntroductionMany low-grade gold and silver deposits and tailing materials from former mining operations in the western United States are potential sources for precious metals. These sources are too low grade or too small to support the capital cost of a conventional cyanidation plant but have stimulated the development of lowcost procedures, such as extraction of the precious metals by heap leaching with cyanide. The Bureau of Mines has investigated methods to improve the recovery ofgold and silver by heap leaching these low-grade materials.For heap leaching to be successful, the crushed and stacked ore must have good permeability so that uniform distribution of the cyanide leaching solution through the heaps can be achieved. Some of the most difficult gold and silver ores to treat by heap leaching are those containing excessive amounts of clays, or fines generated during crushing. Excessive amounts of slimes, generally minus 50-micrometre or 270-mesh Tyler sieve size particles, in the heap feed will slow the percolation of the leaching solution, cause channelling, or produce dormant or unleached areas within the heap, resulting in long leaching periods and low extractions. In extreme cases, the clays or slimes can seal the heap and cause the leaching solution to run off the sides of the heap rather than through it."

Jan 1, 1987

By M. Bourassa, R. del Villar, S. St. Arnaud, J. Valenzuela

"Autogenous grinding is used quite frequently for mineral comminution as a result of its lower capital and operating costs. However, it is more difficult to control than conventional grinding, particularly when the autogenous or semiautogenous mill is the only comminution stage (i.e. no secondary grinding is available). Analysis of the control strategy used then becomes extremely important, a task that is greatly simplified by the use of an empirical dynamic simulator:This paper presents the methodology used in the development and the calibration of such a simulator for the autogenous grinding circuit of an iron are concentrator: The various steps are described: industrial data acquisition, preliminary treatment of the gathered information. and empirical modelling of the process. Finally, both the actual and the proposed control strategies are compared using simulation results.This exercise has shown that the variability of some of the controlled variables could be reduced through a better handling of the water addition and the use of filters on some of the signals used for control purposes. The reduction in variability of critical variables, such as power draw, would allow their average value to be increased without the risk of exceeding their safety values. Some advanced control techniques were also tested, with interesting results."

Jan 1, 1995

By Stephen Hardcastle

Personnel Heat Exposure Issues In Canada?s Deep Mechanized Mines ?Project developed in 2004 ?Base/precious metal industry identified heat stress/management as a major challenge affecting productivity and operating costs ?Project started in 2005 ?Current research nearing completion ?Guidelines, further data analysis and ?Communicating the Science? will continue into 2011 Managing Heat Exposure Control?. The cost implications ?Controlling the environment ?Ventilation already a major expenses/energy user ?Large Canadian mines are currently delivering massive volumes of air 15-20 tons of air/ton ore ?Large investments in ventilation upgrades, mechanical cooling

May 1, 2010

ABSTRACT It is critical that historical processes and concomitant exposures to specific nickel substances be understood because some diseases linked to inhalation of certain nickel-containing substances have a long latency between first exposure and disease onset, and because nickel substances vary significantly in their toxicological properties. A discussion of the smelting history and related processes at Vale Canada’s (Inco’s) Copper Cliff, Ontario, smelter is integral to the understanding of these processes. The post-1950 processing history, equipment, propensity for aerosol formation, operational procedures, and ventilation controls used by Vale Canada in roasting, smelting, converting, and copper-nickel separation is discussed.

Jan 1, 2013

By d&apos, F. Elia

Hot cracking of magnesium (Mg) alloys during welding creates a barrier to enhancing the use of these alloys in automotive applications. As a result, it is imperative to understand the mechanisms responsible for hot cracking of Mg alloy welds in order to develop means of eliminating this problem. In this study, the hot cracking susceptibility of AZ91E and AE42 magnesium alloys were assessed using the moving torch Varestraint test method. Plates of 3 mm thickness were extracted from AZ91E and AE42 ingots and subsequently tested. Quantitative cracking data in terms of maximum crack length (MCL) was used for evaluating the cracking susceptibility. Scanning electron microscopy was carried out. The results suggest that AE42 showed a higher resistance to hot cracking in comparison to the AZ91E alloy. This was attributed to the difference in microstructure between the two alloys. In the fusion zone and HAZ of AE42, the brittle needle-like A1IIRE3 phase was seen to decompose to the more ductile particle-like Al2RE phase, thereby increasing the alloy's resistance to hot cracking. In contrast, SEM fractography revealed that brittle A16Mn and Mg17A112 intermetallic particles segregated to grain boundaries and triggered hot cracking in AZ91E.

Jan 1, 2011

By D. Bois, F. P. Hassani, M. Hossein

"A growing environmental awareness hos prompted the mineral industry to seek innovations in waste management and technology. It is estimated that over 500 million metric tonnes of solid waste each year are rejected by the Canadian mineral industry. This waste hos to be disposed of in the most environmentally and economically acceptable manner.An extensive study has been conducted to estimate the cost of implementing total tailings fill from a waste disposal point-of-view as an alternative to large-scale surface disposal of tailings. The cost of waste disposal at the surface (tailings pond), and underground (total tailings fill) for three Canadian mines which have taken part in Quebec Mine Survey conducted in 1992 are analyzed. Surface disposal is the most economical and common method of mine waste disposal in Canada. Total tailings backfill as a method of waste disposal is technically feasible but cannot be regarded as more economic than surface disposal in all . It is important to remember that while surface disposal costs are rising, due to tighter legislation and more environmental pressure on governments; the costs of preparing and placing total tailings backfill is still falling as the technology improves."

Jan 1, 1994

By William M. Luff

"The Bathurst area has recorded mining production as early as 1837, although the bulk of the production has come in recent years. Production has been mainly from the well-known massive sulphide deposits, but vein, gossan, and a variety of other deposits have also been mined. This paper summarizes the history of the mined deposits, along with tonnages and grades produced.A number of ""firsts"" have been noted in the Bathurst area. The A Zone deposit, located in the Heath Steele area, was the first in the world discovered using airborne electromagnetic methods. Heap leaching of gold from the gossan zone at Caribou was the first operation of its kind in Canada. The Keymet mine was the first base metal (lead-zinc) mine in New Brunswick. For the past few years, the Brunswick No. 12 mine has been one of the largest zinc mines in the world.IntroductionThe Bathurst area (Fig. I) first had mining production in 1837 when copper was mined from a deposit on the Nepisiquit river (MacKenzie, 1958). The majority of the production, however, has been in recent years from massive sulphide deposits, but there are also other significant operations.Table I is a summary of Bathurst area mineral production, showing concentrator feed tonnages and mill feed grades. The table does not include peat deposits, sand and gravel, dimension stone or rock quarries. Figure I is a general geology map of the Bathurst area, indicating deposit locations. The deposits are divided into four categories: massive sulphide, vein, gossan and other. The deposits in each category are described in chronological order of exploitation."

Jan 1, 1995

By M. Kalin

Tailings deposits are frequently the source of ground water contamination due to the transport of contaminated tailings pore-water. If amendments to tailings covers could be made to facilitate a precipitation reaction and halt or reduce the generation of acid in pyritic tailings, the quality of pore-water quality would be improved which would in turn reduce the production of contaminants. The effects of phosphate wastes, added to base-metal mine tailings in Newfoundland, Canada, were tested. Laboratory and field experiments determined the effects of different mixing ratios of phosphate wastes to tailings volume (1:4, 1:8, 1:12 and 1:20, dry weight) for a total period of 3.2 years. The addition of phosphate at ratios of 1:4 to 1:12 substantially increased the pore water pH, and reduced both acidity and Zn concentrations. These results suggest that addition of phosphate wastes to tailings covers can reduce acidity generation and improve tailings pore-water quality.

Jan 1, 2004

By C. T. Wiliams, John B. Bush, John Lamb

"THE TOWN OF HEDLEY is in the valley of the Similkameen River, about 200 miles east of Vancouver and 25 miles north of the International Boundary between British Columbia and the State of Washington. The main ore deposits are located on Nickel Plate Mountain, northeast of the town.The outcrop of the Nickel Plate system of orebodies is at an elevation of 5,900 feet. It was discovered in 1898 by prospectors and sold in the following year to the Marcus Daly interests of Butte, Montana. Production commenced in 1904 under the name of Daly Reduction Company. In 1909 control passed into the hands of the Hedley Gold Mining Company. Operation of the mine continued until 1930, when exhaustion of known ore reserves forced it to close. Upon the recommendation of Paul Billingsley (3) the mine was optioned by the 1. W. Mercer Exploration Company in 1932. Production began once more in 1934 under the name of Kelowna Exploration Company Limited, and was practically continuous until August 1955, when the mine was again shut down. The name of the latter company was changed in 1951 to Kelowna Mines Hedley Limited.The Mascot Fraction, a small wedge-shaped claim lying astride the Nickel Plate orebodies, was mined by Hedley Mascot Gold Mines Limited between 1935 and 1949. The geological setting and structural control of ore are essentially the same as in the adjoining Nickel Plate Mine.Total production from all operations on Nickel Plate Mountain to the end of 1954 was approximately 3,800,000 tons of gold ore, with a gross value in excess of $48,000,000.General GeologyNickel Plate Mountain occupies the gentle westerly dipping limb of an asymmetrical anticline, the axis of which trends northeasterly. The rocks are composed of a thick pile of Triassic limestone, limy argillite, and quartzite, -resting on a flattish floor of granodiorite near the base of the mountain. Associated with these sediments is a host of porphyritic sills and dykes of gabbro-diorite composition. In the mine area east-west brown soda-rhyolite dykes and north-south black andesite dykes crosscut all the other formations and the ore, probably following steep later fractures."

Jan 1, 1949

By A. Roy, T. LeBel, P. Coursol, P. Lind

At the early stage of a mining project, small amounts of concentrates are available for testwork. For gold concentrate or ores containing significant arsenic levels, batch bench scale roasting is often unreliable, leading to highly variable gold recoveries to be used in the project’s financial justifications. With an appropriate bench scale unit using continuous feeding and residence time control for solid and gas phases, reliable numbers can be obtained at small scale with only a few hundred grams per test condition. This paper describes the development of a pilot fluid bed roasting unit by Kingston Process Metallurgy Inc. (KPM) to perform representative trials on gold concentrates containing arsenopyrite, arsenian pyrite and carbonaceous components. Calcines produced under different conditions were characterised by chemical analysis and electron microprobe; the calcine microstructure obtained is described. The most important parameter affecting gold recovery is oxygen content in the roasting atmosphere, with the lowest controlled oxygen level giving the highest gold recoveries. Higher local temperatures in the bed may cause the formation of molten glassy phases which can also reduce the gold recoveries significantly. The impact of roasting conditions in the two inch fluid bed is compared with commercial results obtained in full scale operation.

Jan 1, 2014

By G. W. Evatt

This paper presents the scientific framework underpinning the Resource Valuation and Optimisation Model (RVOM). The RVOM is a Real Options software package, which helps mine owners optimally plan their operations, understand their project risks, and make defensible valuations. This is achieved in the presence of both financial and physical uncertainty. The three key outputs from the RVOM are: Valuation, Optimal Decision and Probability of Decision, where a decision can include any combination of: normal operation, expanded operation, care and maintenance, and abandonment (and variants thereof). This paper presents a clear example of the RVOMs usage to a case-study gold mine.

Jan 1, 2011

By H. Kalsi

"IntroductionRoyal Oak Mines Inc. is currently operating the Parnour No.1 mine located 10.5 miles east of Tinunins, adjacent to Highway No. 101. The operation produces gold ore at a rate of 3300 tpd. A variety of mining methods including bulk open stopes with ITH drilling, narrow vein panel, longhole and open pits contribute to produce 1.2 rnillion ore tons annually. The milling process requires water at an average rate of 1 rnillion gallons per day (700 U.S. gpm). The Pamour No.1 mine has historically had two major problems with regard to water control. The flfSt is the underground pumping system's inability to handle excess inflows of water generated from spring thaws. When the thaw takes place over a short period of time, large inflows of water are created which quickly migrate underground and sometimes result in the loss of the lower loading pocket. During the spring runoff the pumps at Parnour No.1 work continuously for 24 hours at a rate of 1200 U.S. gpm. The system was further taxed in 1991 when the Hoyle mine was connected to the Parnour No. 1 mine and whatever excess capacity the pumping system had for the spring runoff was taken up handling the inflow of mine water generated by the Hoyle.The second problem facing the mine was the lack of water for the mill during the severe cold winter months and dry summer months. At those periods inflows of water into the mine decline and the underground water normally pumped to the mill is severely decreased. In times of dry spells mill personnel increase the water diversion from the Three Nations Lake in order to meet water demands and maintain tonnage throughout. In essence, the mine was going through an annual ""feast or famine"" situation and a solution was needed.A number of options were considered but were narrowed down to the two most practical. The first was to modify the existing pumping system and increase its capacity in order to handle the excessive runoff during spring thaw. This involved a heavy capital expenditure and would have caused additional operating costs (i.e. increased hydro). The option chosen by the management was to divert the spring runoff into an unused section of the mine called The West End. A bulkhead placed at the 2400 level would provide an ultimate underground water storage potential of 150 million gallons. This would also cut down the load on the existing pumping system, save electric consumption in pumping and provide water storage which could be used for milling during the two dry spells. Pumping stored water from the mine could be scheduled for off peak hours to take advantage of lower power rates. To meet these objectives an underground bulkhead capable of withstanding high water pressure up to 2000 ft head (866 psi) was constructed in the spring of 1992. The bulkhead site was at the 2400 level at the Pamour No.1 mine. A major consideration was the requirement to construct a safe bulkhead and to minimize water leakage from the bulkhead.Figure 1 shows the bulkhead location."

Jan 1, 1994

By G. A. Peebles

"This paper describes the various types of radiometric instruments and the techniques of their operation for grade control, sampling, assaying and probing drill holes at Eldorado Nuclear's uranium mine in northern Saskatchewan. Modifications that have been made to these instruments are discussed, and suggestions are made for the development of more refined and specialized radiometric equipment."

Jan 1, 1969

By J. E. Lee

"This paper describes the current practices and experiences, and discusses design parameters concerning slurry pumping at Inco Metals Company in the Sudbury District. It deals mainly with the long tailing and concentrate lines. Subject matter is arranged under the following headings: pumps, lines, instrumentation, system design, operation.IntroductionThe Inco Metals Company is the mining and processing section of INCO LIMITED. In the Ontario Division, it operates 13 mines, 5 mills, a smelter, an iron ore plant and 3 refineries, all engaged in the mining and recovery of nickel and copper. This paper describes the slurry pumping practices in the mills of the Ontario Division.The PumpsWe have in our Sudbury area mills most of the available types of slurry pumps, in sizes from one inch up to twelve inches, a total of about 400 pumps. The rubber-lined, horizontal shaft pump is; most numerous. However, for certain applications, the hard-metal pump is essential, and is becoming more popular for general mill service. Two types of vertical shaft pumps are used. There are a few diaphragm pumps on small thickeners, but the larger thickeners have centrifugal pumps either directly connected to the under-flow or with one pump handling several gravity underflows. We have not used piston or plunger pumps in our mills."

Jan 1, 1978

By James A. Deeks

"Motor failures and equipment bearing failures are responsible for reduced productivity.With the introduction of computers and data acquisition systems, users are now able to monitor, report and trend deteriorating conditions and take corrective action before a critical shutdown occurs.This paper discusses the monitoring and trend analysis of' motors, and motor and equipment bearings. With today's digital electronics technology users are now able to monitor their equipment, detect deteriorating or abnormal conditions quickly, alarm the condition locally and or remotely, and decide if immediate corrective action is necessary or if it can be delayed until the end of a work Shift. All of this can be done long before any damage is done to the equipment.Monitoring Trend AnalysisIt is no longer necessary to compromise in selecting products, since state-of-the-art designs allow the adjustment in such small increments that the users are able to detect minute changes in a system's performance.Monitoring and trending of motors and equipment bearings is now available in economical packages which can be expanded as a system grows. Simply select the information you need, set the parameters, choose the scan time, and decide on the degree of reporting.Buffer storage of short-term monitoring of a number of analogue channels permit the user to view the recent history of motor data such as: motor average load, unbalance, motor current, ground fault, reserve thermal capacity, plus all of the settings of the protective device.A decision can be made to freeze the stored information after the motor stops or after the motor starts. Then the user is able to recall the conditions and diagnose the performance and the cause of the abnormal condition. Typical scan times range from ¼ second to 5 seconds ."

Jan 1, 1992

By Wojciech Naworyta

The development of the Gubin lignite deposit, located in western Poland is the first mining investment of this magnitude in 30 years. Gubin is the second largest prospective lignite deposit in Poland, with over one billion tonnes of indicated reserves, which would be sufficient for a 2700 MW power plant for almost 50 years. The paper presents select problems related to the mining development of Gubin deposit. Attention has been paid to changes in legal and formal requirements for mining investments that were introduced after the change of Polish social and economic system. The significance of spatial, environmental and social conditionings has been emphasized. Typical attributes of the mine planning process have also been presented. Those include the long time horizon of the investment, uncertainty of external conditions and resulting difficulties in the project?s economic evaluation. Focus has been placed on mutual connections between particular elements of the project and time dependence during the process of their development. Iterative characteristics of the design process have been proven, together with resulting necessity of frequent verification of previous assumptions. As a background for presenting selected problems related to future development of Gubin lignite deposit, the methods of design have been discussed ? the variants method, the empirical method and the method of consecutive approximations. The tools and the possibilities of their use for solving specific problems related to mine design of an open pit have been broadly discussed. The chapter in which the authors relate to the specific problems of Gubin deposit development constitutes the main part of the paper. It depicts the assumptions on which the annual production and the total extraction of lignite during life-of-mine period have been based. The process of mine designing has been discussed, taking into consideration environmental, geotechnical, spatial, social and mining conditions. The criteria for choosing the location of the opening cut and the external dump have been mentioned. In the summary, the present state of mine design progress has been presented, together with some problems that will need to be solved during the next stages of the deposit?s development.

Aug 1, 2013

By Alessandro Navarra, Roberto Parra, Boyd Davis, Frank Mucciardi

A smelter scheduling algorithm has been developed, which allocates the oxygen production between the smelting furnace and the converter aisle, so as to maximize copper throughput. The algorithm is intended for daily operation planning, controlling the sequencing of the converter cycles, and the oxygen drawn by these cycles. In some cases, it may be worthwhile to decrease converter oxygen allocation in favour of the smelting furnaces. Thus, a better utilization of the oxygen plant can increase primary copper throughput by several percentage points. This principle is demonstrated through sample computations. The approach presented in this paper can be incorporated into smelter management software.

Jan 1, 2015

Training by Inclusiveness ?Background ?Video ?Results ?Partners ?How SEM works ?Future of SEM Background: Inclusivity partners ?Northwest Community College ?Smithers Exploration Group ?With support from the Province of BC ?Federal government ?And First Nations across the northwest

May 1, 2010

By Louise Laverdure

Outline ?Background ?Issues and considerations ?Why do we need to innovate ?Green Mining Initiative ?Footprint reduction ?Innovation in waste management ?Ecosystem risk management ?Mine closure and rehabilitation ?The Future

May 1, 2011

By Navid Bahrani

Overview ? Case history of footwall slab failure ? Procedure used to build a finite element model ?? Pre- and post- mining topography ?? Slab geometry ?? Excavation stages ?? Input parameters ? Finite element modelling results ?? Unloading-induced displacements (magnitudes & directions) ?? Calibration of overall model using measured prism displacements ?? Shear stresses and displacements along the base of slab ?? Factors of safety at different stages ?? Effectiveness of rock bolts ?? Staged or unstaged model? ? Conclusion

May 1, 2008