Search Documents

By M. S. Diederichs, G. Walton

"Developments in understanding the brittle fracture of rock over the past two decades ultimately led to the acceptance of a cohesion-weakening-friction-strengthening model as an appropriate strategy for the modelling of spalling using a continuum approach. This strength model has been used to replicate observed failure depths and geometries for a number of case studies in the literature, most notably the AECL Underground Research Laboratory in Manitoba. One thing which these case studies typically ignore, however, is the influence of rock dilatancy on the evolution of brittle failure. Physically, this phenomenon is the volumetric expansion of the rock due to fracture opening; numerically, this phenomenon is captured by the flow rule, which is often characterized by the dilation angle, ?. Accurately modelling rock dilatancy in conjunction with strength evolution is necessary both to predict the magnitude and distribution of ground displacements, as well as the exact depth and shape of the fracturing zone. Both of these factors can have significant implications for support design. This paper is focussed on presenting some of the recent developments in this field in the context of a number of numerical modelling case studies. Initially, a new model for the dilatancy of brittle rock is presented, as well as some representative data and model parameters for different rock types. Next, several case studies of highly stressed tunnels and shafts are presented. The results of continuum numerical models are presented to demonstrate the ability of the back analyses to match observed in-situ measurements and obtained. The predictive capabilities of the material model are also highlighted for cases where sufficient “a priori” information (such as laboratory compression testing data) are available. The issues of model nonuniqueness and strain-localization/bifurcation are also addressed."

Jan 1, 2015

By J. Bouchard, A. Clapperton, L. Ebacher, N. Singh

"Canadian Royalties Inc. owns and exploits the Nunavik Nickel project: a copper and nickel deposit in Nunavik, Quebec. Froth flotation is used to produce nickel and copper concentrates. As is the case at other operations, the presence of magnesium is detrimental to the flotation products. In the past year, the exploitation of a new deposit has increased magnesium in the feed. Thus, it has been challenging to meet the required ratio in the final nickel concentrate. In search for a consistent solution for this problematic, an empirical flotation simulator making use of selectivity curves was developed. The circuit was expressed as a system of linear equations, which considered the distribution of copper, nickel and gangue minerals in the different streams. The relative quantities of each mineral are given by the separation efficiency curves of the various banks in the circuit. Three sources of data were used to calibrate the simulator: historical plant data (metallurgical balance), infinite dilution bench-scale flotation tests, and direct sampling of flotation cells. The calibrated separation curves were used to predict the recovery of the different species based on a single mineral recovery. Validation of the simulator showed good fit for the valuable minerals. The simulator was then used to infer the optimal operating conditions of the flotation circuit to optimise magnesium oxide content of the nickel concentrate. Simulation of two re-arrangements of the circuit gave a promising solution with a Fe:MgO ratio 2.42 times higher than the minimum value.INTRODUCTION Canadian Royalties Inc. owns and exploits the Nunavik Nickel project: a copper and nickel deposit in Nunavik, Quebec. Figure 1 shows the location of the mine site. After crushing and grinding, froth flotation is used to produce nickel and copper concentrates. The flotation circuit is designed with multiple stages consisting of bulk copper/nickel flotation, copper/nickel separation, and a separate nickel circuit (bulk float and cleaning)."

Jan 1, 2018

By Li Qihou, Liu Zhihong, Liu Zhiyong, Yao Wei

Black copper sludge, which mainly contains copper, arsenic and a little antimony, bismuth, selenium, tellurium, is an important recyclable secondary resource. In this paper, selective removal of arsenic from black copper sludge by alkaline oxidative pressure leaching was studied. The influences of alkali concentration, leaching time, leaching temperature, oxygen pressure, liquid-solid ratio and other variables on the leaching rate of arsenic, copper and tellurium were investigated. The results were as follows: when the leaching process was conducted at initial alkali concentration of 1mol/L, liquid-solid ratio of 10, stirring rate of 500r/min, leaching temperature of 140°C for 5 h and oxygen pressure of 2.5MPa, the leaching rates of arsenic and tellurium were 85.43% and 59.7% respectively, and copper, antimony, bismuth were not leached. Hence, arsenic has been removed effectively from black copper sludge, while the valuable metals such as copper, antimony and bismuth remained in the residue that can be further recovered easily. INTRODUCTION Black copper sludge is a byproduct in the purification process of copper electrolyte. Arsenic, antimony and bismuth are major harmful impurities in copper electrolytic refining system. The accumulation of these impurities will cause adverse effects, such as the increase of electrolyte resistance and power consumption and deterioration of cathode copper quality (Wang, Liu, & Zhang, 2001). Hence, electrolyte purification is an essential part of the electrolysis process (Liang, Chen, & Guo, 2009). Electrolyte purification methods include electrowinning (Davenport, King, Schlesinger, & Biswas, 2002), solvent extraction (Navarro, Simpson, & Alguacil, 1999), ion exchange (Arroyo et al., 2017), coprecipitation (Wang et al., 2003, 2018; Xiao et al., 2007; Xiao, Cao, Mao, Shen, & Ren, 2014), activated carbon adsorption (Navarro & Alguacil, 2002), electrodialysis (Cifuentes et al., 2015), redox process (Zhou, Peng, Zheng, Ma, & Cui, 2011; Peng, Zheng, Zhou, & Chen, 2012; Zheng, Peng, Ke, & Chen, 2013), among which the electrowinning method is simple in operation and effective in impurities removal, making it the main process for current electrolyte purification. Some copper ions can react with harmful impurities to form complex black copper sludge by controlling the operation conditions of electrowinning process. Based on the estimated data provide by Davenport et al. (2002), an annual output of 400,000 tons cathode copper could produce 432-2168 tons of black copper sludge by electrowinning method. Black copper sludge contains 30~50% copper, 15~30% arsenic and a small amount of rare elements such as selenium and tellurium. Thus, recovery of valuable metals can bring huge economic interests. Moreover, arsenic in these sludges could cause significant environmental pollution. Therefore, effective removal of arsenic from these sludges is urgent and significant.

Jan 1, 2019

By X. J. Guo, H. X. Li

The biological heap leaching at Zijin copper mine is currently the largest industrial application of biohydrometallurgy and one of the earliest mines to develop biological metallurgy technology in China. Since 2001, through demonstration plant and different expansion stages, it has been developed to produce 20,000 tons cathode copper annually. However the ore grade of heap leaching gradually decline year by year with copper grade average at around 0.23% now. The copper mineral is mainly the secondary copper sulfide, and symbiosis with higher content pyrite, the sulfur and iron contents is about 15 times as copper in the ore (S/Cu>15), so the acid and iron treatment of leachate, extractant and acid mine waste water is a great challenge. Combined with located in the rainy area of southern China, huge amounts of over 10 million cubic meters acid drainage need to be treated every year, so the recovery of copper from waste water as well as low grade ore is one of the characteristics of this process. This paper in general introduced the operation of heap leaching, solvent extraction, stripping and electrowinning process in Zijin mine, summarized the experience of production and technical practice, and discussed the methods of heap construction, leaching rate enhancement, third phase formation and treatment, mine effluent treatment, resource recovery and heap slope reclamation. INTRODUCTION The Zijinshan gold and copper mine is located in southeast China, Fujian province, and the typical distribution characteristics of gold and copper deposit are "upper gold and lower copper", both are large porphyry deposits. By the end of 2017, the accumulated proven reserves of available gold resources were 318 tons, copper are 2.15 million tons, and the prospective reserves of copper are more than 5 million tons. The gold mining is open pit while the copper mining is open pit and underground. The cut-off grade of gold mining is 0.15 g/t, and that of copper mining is 0.15%. A large number of very low-grade gold ores (grade <0.30 g/t) adopt a combined ore-dressing process of “partial crushing/ore washing/reprocessing/heap leaching (overlying)/ carbon slurry" independently developed, while flotation and bio-heap leaching are adopted for copper mine. Among them, copper ore with more than 0.25% copper content enters the flotation system to produce copper concentrate, while that of less than 0.25% copper content is processed by bio-heap leaching, solvent extraction and electrowinning. Zijin biological heap leaching plant is the first mine in China to achieve the scale of annual output of ten thousand tons of cathode copper since 2006. In 2008, the solvent extraction and electrowinning system were expanded, now with a daily processing capacity of 20,000 tons of ores, an annual output of 20,000 tons of cathode copper, the expanded plant is the largest biohydrometallurgy plant in China.

Jan 1, 2019

By K. G. Chipman

The Geological Survey is the oldest map making department in the Canadian Government service, and when organized in 1842, one of the first principles to be recognized was the absolute necessity of having good maps. The primary purpose of the Survey has always been geology; but because a graphic representation by means of maps makes the written report .more readily intelligible; because the correlation of known geological facts is often difficult or nearly impossible unless they can be represented on a map; and, because the public demand information shown in this way, the Geological Survey must continue to supply maps; and the supplying of these maps must be considered as an essential part of the work of the Survey. It is a commonly recognized principle of pedagogics that an appeal to the eye is quicker than one to the ear; that children (and others) learn more quickly when a thing is presented to them through the eye rather than through the ear. The application of this principle to the work of the Geological Survey is that, to a large number of people, the message of a map is more quickly grasped, is more readily intelligible, and is in many ways of more interest and value than is the same information in a report. I do not mean that the maps are of more importance than the reports.

Jan 1, 1924

"Here, we statistically proved that giant earthquakes occur at lunar phases specific to each subduction zone. Enough attention during the lunar period, especially when seismicity is occurring, will significantly reduce damage from giant earthquakes. Two case studies in which giant earthquakes occurred after seismicity in dangerous lunar phases were discussed, and the mechanisms underlying why giant earthquakes occur around neap tide at some subduction zones were explained by prohibition of giant earthquake occurrences due to high strain rates at spring tides at N–S subduction zones. The prohibition was statistically proven for uniaxial creep tests on Inada granite with slight stress disturbances. INTRODUCTIONIn previous studies, we showed that from 1900 to present, giant earthquakes (MW ??8) have occurred at lunar phases specific to each subduction zone (Fujii & Ozaki, 2012; Ozaki & Fujii, 2012). Although we later proposed a possible reason for these occurrences, the study lacked statistical analyses (Fujii et al., 2013). Therefore, this paper shows the results of such statistical testing and presents case studies for the Tohoku 2011 and Chile 2014 events, thereby providing updated data on giant earthquakes through July 2014."

Jan 1, 2015

By E. Lampard

Mines must manage variability from within their operations as well as those imposed upon them by external forces. This paper provides a framework to manage both internal and external variability through the review and adjustment of the mine plan where applicable to minimize lost production and maintain operational safety. KEYWORDS Mine plan, mine schedule, variability, safety, lost production, float days, update, adjustment, operations, Maintenance

May 1, 2011

By C. H. Hopper

DIAMOND drills have played an important part in the development of mines for many years. Recently. they have also entered the production field arid the use of diamond drills m the primary breaking of ores has become a big branch of the industry. The writer has estimated roughly that the total diamond drilling in Canada during 1942 was 5,625,000 feet, of which 2,250,000 feet, or 40 per cent, was for blast-holes. This accounts for 6,750,000 tons of ore broken, using the conservative factor of 3 tons per foot of hole. Many consider that the use of diamond drills for blast-holes is the most important advance in mine practice of the past decade, and the industry owes a great deal to the staff of Noranda Mines, Limited, for the pioneering they have done in the development of long-hole mining methods and for publishing their results. A great many mines have followed Noranda&apos;s lead. At the Waite-Amulet, Aldermac, Flin Flon, Canadian Malartic, Hoyle, and Matachewan Consolidated mines, most of the ore is broken by long-hole blasting. While the mines were developing new methods, the diamond-drill industry was developing mechanically-set bits and better machines. Through the effective use o smaller, cheaper diamonds, as well as more efficient setting, bit costs per foot are only one-half what they were ten years ago. Few people realize that a diamond bit is relatively inexpensive. The common EXT coring bit, for example, contains some 200 small diamonds, weighing altogether about 2.70 carats which, at $3.40 per carat, cost $9.20. After use, the equivalent of about 100 of these diamonds may be recovered. Therefore the true cost of the bit is only $7.00, made up of $4.60, the cost of the diamonds lost, $2.00 for setting, and $0.40 tax. The trend in machines has been toward specialization for the different classes of rock in blast-hole work. Light, high-speed machines have been developed for soft ores and higher powered machines for hard ores.

Jan 1, 1943

By Shintaro Takamiya, Kazunari Yoshida

"Recently, small sized micro-needles for medical are required more frequently by patients. The biggest reason is that it presents great burden on the patients, due to the size of the needle injection. People need to use a very small needle to lower the pain, but the downfall is that it makes them more expensive due to their complicated manufacturing method. Therefore, we need to fabricate a needle by wire-drawing to decrease its price. Tube-drawing is beneficial for its production value; however, in conventional tube-drawing it is difficult of control the wall thickness of the tube and makes it 1mmor lower in diameter. That is why, we propose fluid-mandrel drawing for new tube drawing. This method allows fabrication of a fine tube by using the pressure of the fluid in the tube. In this research, the goal is the fabrication of a fine tube by fluid-mandrel drawing and its evaluation. Finally, the fabrication of a fine tube by fluid-mandrel drawing was conducted and in result a tube with a diameter of 0.2mm, high strength and thin wall and fine inner surface was drawn, which can be used as a lesser pain micro-needle.INTRODUCTIONThe main manufacturing method of the current medical needles is roll forming. With this method, it is difficult to make a tube with a diameter lower than 1mm. Deep drawing has been proposed and used as method to further reduce the diameter, but this method is costly and the injection needle obtained by this method is several times more expensive.Therefore, we need to obtain a fine medical needle by drawing process that can be mass-produced and inexpensively manufactured. However, with the conventional drawing process, it is not possible to obtain a syringe needle with a reduced diameter easily, that is why, a fluid-mandrel drawing has been proposed which can reduce the diameter without damaging the inner surface. The methodology of the method is, a fluid is filled in the sealed tube and the pressure inside the tube during drawing is responsible for the good inner surface and wall thickness. It is also expected that the fluid can be easily discarded and that the tube can be manufactured on a long scale."

Jan 1, 2017

By W. Evans, C. E. Ells

Nuclear power reactors using zirconium alloy pressure tubes generate electricity in several countries. Such reactors are particularly important in Ontario, where CANDUs* generate about 30% of the total electricity produced in the Province. Starting with the commitment of NPD-2 in 1956, the pressure tubes of the first five CANDU reactors were made of coldworked Zircaloy-Z, an alloy of Zr and Sn. This alloy was developed by the US Navy, but the decision to use it in a cold-worked condition was based on AECL work. In 1958, the USSR published information on a new alloy, Zr-2.5 wt% Nb. The Nb promotes stabilization of the (3-phase in the material, thus presenting opportunities of exploiting metallurgically strong pressure tubes analogous to the heat-treatable cx-{3 titanium alloys. After construction of two reactors using Zr-2.5 wt% Nb in a quenched and aged condition, an extensive development program on cold-worked Zr-2.5 wt% Nb pressure tubes resulted in them becoming the reference tubes for all CANDU reactors committed since 1966. Anticipating the future needs of the domestic and export markets, AECL have pressure tubes of Zr-3.3 wt% Sn-0.8 wt% Nb-0.8 wt% Mo (Excel) in an advanced state of development. These tubes will be used in an annealed condition; our projections show that they will have improved dimensional stability over the lifetime of the reactors. These improvements result from experimental programs leading to an understanding of the relationship between microstructures and fabrication variables and effects of the environment during service in nuclear reactors.

Jan 1, 1981

"A growing public awareness of work-related diseases such as pneumoconiosis and the impact of this awareness on legislative bodies and on the skilled labour market are reasons why the Canadian mining industry must consider dust control of top-drawer importance. Measurements and standards related to the hazard are necessary to control a dust situation and to avoid excessive risk. The author discusses some of the methods of measurement, standards proposed and terminology used in this developing technology. The purpose primarily is to give a better understanding of the basic advances achieved by those who have applied current knowledge with a measure of success."

Jan 1, 1972

By P. D. Hodgson, G. L. Kelly, H. Beladi

"The formation of ultrafine ferrite by strain induced transformation is assessed using rolling and hot torsion experiments. These experiments are used to examine the impact of thermomechanical processing conditions and steel chemistry on strain induced austenite to ferrite transformation and the formation of ultrafine ferrite. The critical strain for dynamic strain induced transformation increased with increasing carbon equivalence, deformation temperature and austenite grain size. The deformation structure in the austenite grains changes with the thermomechanical processing conditions.Drawing on these results and the current literature, the important factors for the production of ultrafine ferrite are described and a mechanism proposed."

Jan 1, 2004

By C. A. Rowland

"Plant owners and operators, plant designers and grinding mill manufacturers are giving much attention to the design and manufacture of autogenous and semi-autogenous grinding mills, particularly the mills that have large diameters and draw power up to 10,000 hp and greater. Reliable designs giving long operating lives are required in today &apos;s ore processing plants.This paper reviews bench-scale and pilot-plant testing to determine first if the ore is suitable .to be ground by these methods and then reviews the data obtained from pilot-plant testing that is used to select the mills and the grinding circuit. The paper then discusses the use of the pilot-plant results to design the mills. The most important pilot-plant data used for mill design are power and the amount of ball charge to be used. The mill size selected is a combination of these factors. Pilot-plant data not only establish power requirements, but can be used in the selection of the type of drive, variable speed or fixed speed, and the operating procedure to be followed. This leads into the mill control circuit to be used. The total charge in the mill, the type of drive and mill discharge arrangements are needed in the calculation of stresses and bearing loads. Conclusions reached from pilot-plant work are used to obtain data for process design, and autogenous and semiautogenous mill design should be part of any test program incorporating either or both of these grinding methods."

Jan 1, 1981

By Daniel J. Schulze

Abstract-Eclogite is an important source of diamond in the upper mantle, but is more localized than peridotite. Using eclogitic minerals in kimberlite and diamond exploration is also more problematic than using the well-known peridotite-derived indicator minerals Cr-pyrope and magnesiochromite. The problems include color similarities between orange garnets from eclogites, Cr-poor megacrysts, and crustal garnets, chemical similarities with Cr-poor megacryst suite garnets (specifically elevated Na2O contents), and low abundance of eclogite garnet xenocrysts in most known kimberlites. Chemical screens must be used carefully to distinguish between varieties of orange garnets in exploration samples. For example, most orange garnets of crustal origin have >22 wt% FeO, with mantle eclogite garnets having lower values. Na2O-bearing garnets from the Cr-poor megacryst suite can be distinguished from Na2O-bearing garnets from diamondiferous eclogites by the elevated TiO2 contents of the former. The low abundance of eclogite garnet xenocrysts in kimberlites worldwide, however, may dictate that use of eclogite garnets in diamond exploration in most cases be restricted to advanced stages of kimberlite exploration and evaluation of kimberlite diamond potential. Crpyropes, Mg-ilmenites and Cr-rich chromites are more useful than eclogitic garnets in most stages of diamond exploration. If orange garnet xenocrysts are sought in a kimberlite exploration program, those from the Cr-poor megacryst suite will be more useful than eclogite derived garnets, due to the typical great abundance of the former, although they carry no information of the diamond potential of the host kimberlite.

Jan 1, 1997

By J. C. Hampton, L. A. Matzar, C. R. Gamwell

In geomechanics, conducting uniaxial or triaxial compression tests require samples to be prepared to a certain length-to-diameter ratio. This ratio is typically defined as 2:1 (length to diameter) and is accepted as a common standard for all materials on which mechanical properties testing is performed. Variations in sample length can cause changes in measured strength properties across multiple material types, such as cement, rock, or soil. Within the oil and gas industry, it is not uncommon to receive samples for technical services work that are slightly under or exactly the length requirement before surface grinding and sample preparation. Many of these samples are discarded from uniaxial and triaxial compression tests and used in another manner; therefore, it is necessary to study the length-to-diameter ratio in efforts to understand the limits and validity of testing samples that are slightly out of the 2:1 ratio. This paper discusses uniaxial compression tests performed using Berea sandstone and a standard cement mixture of 2.54-cm diameter to study changes in rock strength and properties. Compressive strength for each lengthto- diameter ratio over a range of 0.5:1 to 2.2:1 was measured. The investigation was extended to study near-end effects, where the sample length is near, but not exactly twice the diameter. It was discovered that the cement samples conformed reasonably well to the suggested ASTM correction factors. The sandstone did not conform to the correction factors and further analysis is required to develop a correction factor unique to the material. Near end effects, in both the cement and Berea, were found to increase compressive strengths, especially when the L/D of the samples was increased slightly over a 2:1 L/D.

Jan 1, 2015

By Therese Schneck

The presence of xenon isotopes from in-situ spontaneous fission of short-lived Pu244 has been confirmed in Hadean detrital zircons from Western Australia. Hadean and meteoritic zircons can retain secondary overgrowths developed after primary cristalization at 3.97-3.94 Gyr. On the moon, the metal grain in sample 66095,78 is mantled by troilite, schreibersite and cohenite. High chlorine content FeCl2 is deposited around metallic FeNi. The magnitude of Pollonium-210 to Radon-222 on the Aristarchus plateau spectrum indicates a past greater activity. The Earth Moon system from Nb/Ta systematics is consistent with a Moon iron core delayed to 3,9 Gyr.

Aug 1, 2010

By A. J. Neale, B. C. Flintoff

"A review of the dynamic rod mill-ball mill grinding circuit simulator developed at the University of Alberta, highlighting the modular structure and open-ended design, demonstrates the ease with which classical feedback control strategies can be designed and implemented. Various open loop simulations are presented to demonstrate the highly interactive nature of the grinding circuit and to indicate where potential control problems may be encountered. Closed loop simulations are examined, beginning with the basic SISO classical feedback control of circuit product size. Further improvement in the grinding circuit performance in the presence of various disturbances is realized through the application of a classical MIMO feedback controller. As an example of advanced (multivariable) control, static decoupling is implemented and shown to provide additional improvement in overall circuit performance.INTRODUCTIONIt has long been recognized in the processing industries that a dynamic process simulator is an indispensable tool in the design and evaluation of automatic control schemes. In mineral processing the lack of these simulators is felt to have been a major hindrance to the widespread implementation of effective process control systems. In particular dynamic simulation is a necessary precursor to any study of modern (as opposed to classical) process control methods. This paper discusses the development of a dynamic simulator that can be used to study various feedback control strategies. The simulation software provides a powerful educational tool for those individuals interested in grinding circuit control."

Jan 1, 1988

By R. P. Mahant

"Extensive pilot plant investigations were conducted both on partial roasting an d electric furnace smelting from September 1973 to August 1975.The objectives of the pilot plant investigations were:(I ) to confirm the application of available process technology to treatment of Falconbridge concentrate.(2) to examine partial roasting variables.(3) to investigate electric furnace smelting of roaster calcines .(4) to develop process design and operating parameters for a commercial plant.This part of the paper will cover the following topics:Partial Roasting InvestigationsPilot Electric Furnace InvestigationsPartial Roasting InvestigationsThe specific objectives were to:1. establish process variables for maximum oxygen efficiency and bed fluidi ation.2. determine the product distribution between the roaster and the various gas cleaning stages.3. produce a mass and thermal balance."

Jan 1, 1984

By T E. Tibbetts

This paper deals with coal sampling in general and with mechanical coal sampling in particular. The necessity of obtaining representative samples is emphasized. Other sections of the paper are devoted to the design and selection of automatic samplers, with a consideration of the three main types, and the testing, operation and maintenance of these samplers. The cost of the installation of an automated sampling system must be related to the value of the material to be sampled, to the volume of coal involved, and to the savings in labour and economy which can be achieved. Introduction T HE Committee?:; on Coal Sampling of the Coal Study Subsection, Thermal Power Section (Eastern Zone), Canadian Electrical Association, was established in November, 1963, to "study the various problem areas of coal sampling." The first undertaking of the Committee was to at-tempt to survey the problem areas of coal sampling through an evaluation of coal sampling difficulties as experienced at both the plant design and operational levels within the electric utilities represented on the Committee. The results of this enquiry indicated that satisfactory answers to almost any conceivable

Jan 1, 1965

By A. Dave Mackintosh

Historical closure data has provided a description of the stress distribution patterns occurring around mine openings and enabled the development of a time ? distance plot predicting the location of the stress peak and its migration away from mine openings with time. Data collected from active mining areas during the 1970?s and 1980?s indicated the peak appeared to stabilize approximately 135m (450 ft.) from openings after four years. The region of high load and accompanying poor ground conditions in which the peak was centred was spread over approximately 45m (150 ft.) to 60m (200 ft.). Recent data from new development headings cut adjacent to 25 year old extraction areas suggests load transfer takes place over a much greater distance and time frame than predicted.

May 1, 2001