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By S. B. Patton

A comprehensive approach to the development and organization of an expert system that is designed to assist electricians in diagnosing electrical faults m mining machinery is discussed. The system includes diagnostic, reference, and tutorial programs. The diagnostic portion of the system is based on a causal-reasoning approach which is used to establish a hierarchy of symptoms and the subsequent production rules for identifying component-level failures m the motor-control circuit of a shuttle car. With this approach, conclusions are developed directly from knowledge of the circuit and its behavior (in both working and failure modes) based on first principles, rather than the heuristics of a domain expert. The symptoms and their hierarchical structure an: formulated by creating "what-if" scenarios and performing a qualitative circuit analysis for each fault Techniques for incorporating interactive graphical displays of the circuit schematic into the diagnostic portion of the system are also presented. Supportive computer programs that provide' reference material and tutorials on the circuit are also described.

Jan 1, 1989

By Finn Ouchterlony, José A. Sanchidrián

"A model for fragmentation in bench blasting that originates from dimensional analysis of fragmentation in asteroid collisions is presented. Percentiles of the size distribution are obtained in the basic model as the product of a rock strength-to-explosive energy ratio, a bench shape factor, a scale factor or characteristic size and a percentage passing-related factor. The parameters of the model are fitted to 169 bench blasts in different sites and rock types, bench geometries and delay times, for which thefragmentation of the muckpile was obtained by sieving. The basic model is found to significantlyimprove with an additional factor describing the rock mass structure in terms of the spacing and orientation of discontinuities, and another one describing the delay between successive contiguous shots; the latter is conveniently formulated as a function of the P-wave velocity and the holes spacing. The rock strength property chosen is the strain energy at rupture that, together with the explosive energy density in the rock (or energy powder factor), forms a combined rock strength/explosive energy nondimensionalfactor. The model, called xP-frag, is applicable from 5 to 100 percentile fragment sizes, with all parameters determined from the fits significant to a 0.05 level. The expected error of the prediction is below 25 % at any percentile. These errors are half to one third of the errors expected with the best prediction models available to date."

Jan 1, 2017

By Jan A. Nilsen

This paper describes a key element in the construction of a major project undertaken by Harbourfront Corporation in its efforts to rejuvenate the central Toronto waterfront. The Spadina Pier forms one of the two major structures of the $10 million marina complex. Completed in early 1986, the 150 metre(490 ft.) long by 43 metre(140 ft.) wide pier structure will contain a 320 car parking garage as well as providing the foundation of a 17-story residential tower and a two-story retail/commercial complex. However, the pier structure posed a considerable challenge to its developers due to the the many restrictions imposed on the site by the environmental authorities which ruled out the construction of dykes or the placing of other fill materials on the highly contaminated bottom sediments. In addition, access at the site was restricted by its proximity to the main harbour navigation channel and a grain elevator berth. The original design called for a cofferdam to form an integral part of the finished structure. However, the contractor chose to regard the cofferdam as a temporary structure and proposed to construct the pier in the dry by enclosing the 10,000 square metre(107,600 sf) site with a 450 metre(1480 ft.) long single wall steel sheet pile cofferdom 7.5 metres(25 ft.) from the final pier structure. This paper will describes the design and construction of the cofferdam. Prior to finalizing the pier design, a geotechnical investigation of the shale bedrock was undertaken as well as a small sheet pile test cell program to evaluate the feasibility of driving a Canadian manufactured cold-rolled sheet pile into the bedrock. Relying on the design parameters for the shale bedrock, Foundation designed the cofferdam utilizing a post-tensioned bipod bracing system to resist a 7 metre(23 ft.) hydrostatic head as well as the maximum wind and wave forces expected at the site. The bipod bracing system consists of diagonal H-pile raker piles and verticle pipe piles anchored to bedrock with post-tensioned anchors grouted into bedrock.

Jan 1, 1987

By Qingguo Xue, Jingsong Wang, Yingli Liu, Guang Wang

In the dropping zone of blast furnace (BF), primary slag absorbing ash of pulverized coal and coke become to be intermediate slag. Due to viscosity and surface tension of slag and the pore between cokes, some slag remained in coke layer and affected the permeability of blast furnace. The flow behavior of slag with different basicity (0.55–1.10) and Al/Si (0.35–0.50) were studied. Meanwhile, the viscosity and surface tension of slag were calculated. The results showed that, with the increasing basicity of slag, surface tension increased and viscosity decreased. With the Al/Si increase, surface tension and viscosity increased. The smallest pore that all slag can pass through was 4.5 mm. However, the height between slag droplets and the bottom of crucible indicated that the ability of slag to pass through pore were weakened with the increasing basicity and Al/Si. Thus, slag which absorbed ash from fuel become difficult to pass through coke layer.

Mar 1, 2017

By L. Y. Feng

The percentage of leached zinc in massive zinc oxide ores (11.7% Zn, >2 mm) is up to 73.3 % in 120 days. Alternatively, crushed to -0.154 mm, mixed with cement 5% (wt), pelletized and solidified. The diameters of the pellets obtained are between 5 mm to 8 mm. When the pellet solidification periods are 3 days, 10 days and 45 days respectively, the alkaline leaching rates of zinc in the pellets are up to 95.8%, 89.1% and 76.4% respectively. Decreasing the solidification time can re-duce reaction time, increase dissolution of zinc in pellets and lower the effect of initial zinc concentration on leaching rate. The experiment results show that the minimum solidification time is three days, and the kinetic study indicates that alkaline leaching of the low grade zinc oxide pellets is controlled by the diffusion of the leach liquor through the gangue layer in the whole leach process, and the apparent rate constants are 3.33×10-2 day-1, 9.18×10-3 day-1, 5.82×10-3 day-1 respectively.

Jan 1, 2014

By E. Laine

Rock density determinations are necessary for ore resource evaluations from estimated block grades in g/t. Rock density depends on the mineral composition and, thus, it is specific for each rock type. The rock density distributions for different rock types are often symmetric. Hence, the arithmetic mean is a good approximation for the average density for lithological units. However, there may exist spatial variation in density values due to alteration, fracturing and original heterogeneities such as layering. This study compares the kriged density model with the one with constant density values for different lithological units in the evaluation of metal amounts in rock blocks. The case study consisted of rock densities measured from the drill cores at Ahmavaara PGE deposit in northern Finland. The used Ni contents were simulated in accordance with the spatial distribution of rock densities. The Ni amounts in 2x2x2 m3blocks are higher for the kriged densities than for the average densities. The difference is increasing with the increasing metal amounts due to the nonlinear correlation between Ni content and rock density. The final effect on the resource estimation depends on the cutt off grade and prices of the metal, for example, for a very valuable metal the small differences are significant

Jan 1, 2003

By Filmer AO

In contrast to the '50s and '60s, the period of the '80s and '90s seems likely to have low growth in demand but much greater levels of technological change. In such a climate there will be pressure on costs, productivity will continue to rise and competitiveness will be closely associated with maintenance of the most effective technology. The penalties for inappropriate investments, whether short sighted or mistakenly based on a particular view of the future, will be greatly enhanced. Accordingly, there will be a need for significantly improved anticipation of technical change and thus for better planning. Study of the funding and direction of the world's R&D effort can provide a useful input to the planning processes within industries and individual firms. Such a study also suggests some insights into the characteristics of those countries which have achieved substantial growth and high standards of living over the past two decades. These characteristics may offer significant reminders for our own development. The particular implications for the Australian minerals industry include the need for direction that is sensitive to changing market requirements and customer practice. This is not simply "more of the same." In particular it appears essential for both basic and applied R&D to provide a sound basis for the purchase and ongoing development of the new technology required to achieve international Competitiveness.

Jan 1, 1986

By K. Burke, G. Zhan, A. Mayer

A cover with capillary barrier effects (CCBE) is being constructed on the AA Leach Pad at the Barrick Goldstrike Mine site near Carlin, Nevada. The purpose of the cover is to eliminate/minimize infiltration of meteoric waters into the leach pad. Laboratory and numerical analyses indicate that Carlin Formation siltstone (TCS), a locally available material, has the necessary hydrologic characteristics when placed on the leach pad to act as a CCBE. A pilot study has been conducted on a small-scale test cover placed on the AA Leach Pad to examine the cover performance under irrigated conditions. The preliminary test results demonstrate that the designed cover is capable of preventing meteoric water infiltration.

Jan 1, 2001

By Charles D. Walcott

The following acts of the Directors are reported for the information of members At a meeting held June 20, 1907, Dr. Charles D. Walcott, Director of the U. S. Geological Survey, Washington, D. C., having been recommended by unanimous vote of the Council, was unanimously elected an Honorary Member of the American Institute of Mining Engineers, in recognition of his personal services to American geology, and of his generous co-operation with this Institute, to the Transactions of which he has not only himself made valuable contributions, but has also encouraged the preparation of such contributions by the members of the U. S. Geological Survey under his charge, his liberal policy in this respect having gone so far as to permit the preliminary publication by the Institute of important results reached by the geologists of that Survey, even before their final and full publication as public documents. This wise and generous course has not only brought the U. S. Geological Survey into intimate and sympathetic relations with the mining industry of the world, but has also enriched the Transactions of the Institute, especially in the department of the science of ore-deposits, with many valuable papers. At a meeting held Jan. 14, 1908, Mr. Charles Kirchhoff was unanimously re-elected a Trustee of the United Engineering Society, to serve for a second term of three years. At a meeting held Feb. 18, 1908, directly after the adjournment of the annual meeting of the Institute, the following officers were elected for the ensuing year: President, James Gayley: Vice-President, James Douglas; Secretary, R. W. Raymond; Treasurer, Frank Lyman.

Mar 1, 1908

By Eugie Kabwe

The velocity of detonation (VOD) is a significant property considered when rating an explosive. It may be quantified as a confined or unconfined velocity. The confined velocity is the rate at which the detonation wave propagates through an explosive within a blast hole or any restrained space. The unconfined velocity emanates when an explosive is detonated in the open. However, the confined velocity is more significant as explosives are usually employed under a definite degree of confinement. This paper evaluates the increment of air deck volume and its effect on the VOD. The air gap (air deck) volume is increased stepwise from 10 to 30% of the total blast hole volume by reducing the stemming height in the collar zone. Thereafter, the VOD estimation in the 172-mm-diameter explosive column is conducted using the Dáutriche technique. It is observed that the VOD reduced with the increasing air deck volume and detonation failure is high when 30% of the blast hole volume is replaced with air deck. It is deduced that the increment of the air deck volume has an effect on the attenuation of the steady-state VOD.

By C. Birch

"The purpose of this study was to establish the impact of discount rates on cut-off grades for narrow tabular gold deposits as characterized by the goldfields of the Witwatersrand Basin in South Africa. There are various methods available for determining the cut-off grade, from simple breakeven calculations to sophisticated software packages that consider a variety of inputs to optimize the cut-off grade. For this study a simple financial model was created in Microsoft Excel® that links the ore flow, block listing, and the cash flow. This allows the cut-off grade to be optimized considering how the cost of capital and chosen discount rate affect the cash flow.The discounted cash flow (DCF) and resultant net present value (NPV) are a widely used valuation method for production properties according to the South African Code for the Reporting of Mineral Asset Valuation (SAMVAL Code). The financial model in this study utilizes the Solver function, as well as simple Microsoft Excel spreadsheet formulae to optimize the NPV. Solver was chosen as it is a standard feature in Excel and thus no additional software costs are incurred beyond the basic Microsoft Office suite. For the purpose of this study, just narrow tabular gold deposits of the Witwatersrand Basin were considered. An example of a typical ore block listing, as well as the costing figures, was obtained from an operating gold mine. The results obtained from the study financial model were compared to the current cut-off grades obtained from the mine using their proprietary optimizer program, and were found to be comparable. The methodology utilized for this study thus appears valid.The cut-off grade was optimized considering the cash flow, which includes the variable mineral resource royalty tax, the variable gold income tax, as well as the discount rate. By comparing the resultant NPVs using discount rates of zero, 9%, and 12%, the impact of the discount rate on cut-off grades, resultant life of mine, and average mining grades (AMG) could be compared for the example ore block listing. The South African Code for Reporting of Exploration Results, Mineral Resources and Mineral Reserves (SAMREC Code) does not require operations to state if a discount rate was considered in determining mineable reserves. Mining companies approach the question of applying discount rates in determining their cut-off grades, and thus mine planning strategy, in different ways. Due to the negative impact that optimizing purely on NPV has on the life of mine, some choose to optimize only on profit. Other companies have reverted to utilizing pay limits as their primary grade planning strategy. The calculated cut-off grade is then considered to be another planning indicator rather than a hard determination of mineable reserves."

Jan 1, 2016

By Jr. Zink

An economic and operational evaluation of the unrecovered metal, physical conditions, and chemical environment in a leach pad should be made prior to decommissioning. This evaluation will help determine the possibility and method of secondary and/or enhanced metal recovery and the method(s) to be used for detoxification and heap closure. The evaluation requires quantitative sample collection in a locally variable, yet grossly homogenous material. An assessment of a valley fill heap leach pad was made using a technique borrowed from placer technology called sonic drilling. The sonic drilling technique produced very satisfactory core recovery and sample quality. At this site, drilling results demonstrated that the method of heap construction produced expected features after extensive long term leaching. Rather than a uniformly homogenous pile of metallurgically depleted crushed ore, an assemblage of solution channels, un-oxidized sections, unleached areas, and compaction due to various factors, were found. These conditions are thought to represent a normal, rather than unique, situation for a valley fill heap leach. The lack of this information can have a significant impact on the economics and methods of heap re-handling and ultimate closure.

Jan 1, 1992

By L. J. Cunningham

I THINK it can be safely said that no mining operation, whetl1er open-pit or underground, is ever entirely free of water. It follows that every ton of ore bears a charge which represents, either directly or indirectly, the cost of keeping the mine workings as dry as possible. Water problems occur in all phases of mining operations. They cause difficult and costly drilling conditions during the exploration stage, they often seriously delay mine development, they can slow mine production and reduce efficiency, and they are a continued burden over the life of the mine. It is therefore in the interest of all mining men to be familiar with the methods and materials used for grouting. The most common grouting material is cement. Cement grouting is old and well established, and many engineers are familiar with its uses and limitations. The technique of cement grouting is relatively simple and fairly well understood, and the materials utilized are relatively in-

Jan 1, 1962

By W. M. Houston

The phosphate formations of the Pliocene epoch were deposited along the coastal shelf of the eastern seaboard. The deposition of the phosphate is thought to be somewhat contiguous along the early shoreline, and the deposit can be more or less traced over an 800 to 930 mile path from the Florida Gulf Coast, near Ft. Myers, to the Pamlico Sound of North Carolina. This is illustrated in Figure 1. Three areas of commercial importance are currently being exploited from this extensive known deposit: 1 - The so-called ?Bone valley? in Central Florida (multiple operations) 2 - Hamilton County in North Florida (Occidental Corporation operation) 3 - Beaufort County in North Carolina (Texas Gulf Sulphur operation)

Jan 1, 1966

By W. J. Bennett

WHEN Dr. Horace Fraser, your President, invited me to speak to you today I advised him in confidence that I was leaving my present positions on April 30th. In the circumstances it seemed to me that this audience might prefer to have as its speaker one who wo.uld J1ave a continuing association with the atomic energy programme. Dr. Fraser was kind enough to suggest that my re-marks might he of special interest to you, since I would be able to sum up my views on the atomic energy programme. I hope that I will not disappoint him or you on that score. I am particularly pleased that my last public appearance in my present positions should be at the Annual Convention of the C.I.M. since, as all of you know, a very important part of my work has been in the mining field. As it happens, my first public address on the subject of atomic energy and its raw material -uranium -was made at your Annual Convention in Montreal in April, 1949. It seems fitting that my final address should also be made at this convention -nine years later.

Jan 1, 1958

By Jagdish C. Agarwal

Although copper ranks very low in the order of abundance of elements in the crust of the earth, it has been one of the first metals utilized by mar, at his emergence from the Stone Age, about 10,000 years ago. Use of copper for weapons, tools, utensils and ornaments dates back to the twilight of history, 6,000-5,000 B.C. Native copper outcrops and the malleability of the metal explain its very early use by the cave-dwellers. The working, melting and extraction of copper from its minerals are among the oldest metallurgical achievements of the human race. The oldest complete smelting installations for the extraction of copper from its minerals, dated about the fourth millenium B.C., were recently discovered in the Timna Valley, Wadi Arabah, Israel. (1) The history of the developments of the extractive metallurgy of copper has been adequately reviewed recently. (2,3) The center of copper production migrated from the Eastern Mediterranean to Northern Europe (Mansfeld, Germany, Swansea, Wales) towards the end of the Middle Ages (1500 A.D.). The production of the metal was boosted tremendously in North America since the end of the nineteenth century (Fig. 1).

Jan 1, 1976

By P. R. Swann, J. G. Parr

Quenched structures were studied in alloys containing up to 12.5 pct cobalt. The subsequent decomposition of a 10 pct cobalt retained-ß phase alloy was investigated using metallographic and X-ray diffraction methods. Hardness measurements also were made during the decomposition process. Precipitation of Ti2Co is by nucleation and growth; and an activation energy of 50,000 cal per mole was determined. The values of the coefficient ß suggest that the precipitate is pearlitic at temperatures between 450 and 475°C, and spheroidal between 500 and 525°C. THIS paper describes part of a series of invesligations into phase transformations in binary alloys of titanium with transition elements. The general approach is similar to that taken in work on titanium-iron and titanium-nickel alloys.' Previous investigators'' have established the titanium-rich end of the titanium-cobalt phase diagram, reproduced in Fig. 1. Orrell and Fontana' showed that alloys containing more than about 6 pct" cobalt quenched from the ß range, produced 100 pcl retained-p phase. The isothermal decomposition of alloys containing between 0.8 pct Co and 15.5 pct CO was investigated by the same workers in the temperature range 650 to 1000°C. They reported that these alloys transformed into a or Ti,Co depending on the cobalt content, but no quantitative data were given. In the work to be described a series of alloys containing 0.8 pct Co to 12.5 pct Co was examined in the quenched condition. The 10 pct Co alloy (the lowest cobalt content to retain 100 pct ß on quenching) was selected for further work on the tempering kinetics of the ß decomposition. Experimental Procedure Since our own melting equipment was not installed at the outset of this work, the Physical Metallurgy Division of the Department of Mines and Technical Surveys (Ottawa, Canada) prepared the alloys. These were made of Japanese sponge, (which when melted had a value of 103 DPH, using a 1-kg load), and electrolytically prepared cobalt. The al- loys, made up to contain 0.8, 1.6, 3.3, 5.8, 8.3, 10.0 and 12.5 pct Co, were homogenized by swaging into rods at 900°C. Filings were taken from the rods, and any iron chips from the file were separated magnetically. Size fractions of both plus and minus 200 mesh (about 75p) were shown by their constitution, after annealing just below the eutectoid temperature, to contain the same cobalt content. Consequently, it was permissible to use the —200-mesh fraction, knowing it to be representative of the rod composition. Quenching in argon was carried out in a newly designed furnace, whose features include (1) an Inconel furnace tube, (2) a positive pressure of argon maintained at all times in the furnace—even when a sample is removed or inserted. The furnace is shown in Fig. 2 and is described in the Appendix. The tempering processes were carried out on powder samples sealed in evacuated quartz capsules. Since the highest tempering temperature was 525OC, no protection against reaction with the quartz was necessary. (Tests were made on filings of iodide titanium and showed no hardness increase after equivalent heat-treatments.) A thermocouple was attached to the capsule, which was heated to the

Jan 1, 1959

By S DeKruijff

The Mount Isa Mines Copper Mine in Mount Isa started producing copper in 1966. The Copper Mine gradually increased production rates to nearly six million tonnes per year. Over the last three years the mine has been in a gradual ramp down due to the reduction of primary ore sources and head grade. The majority of ore sources are predominantly in pillar retreat sequences bounded by multiple fill masses. There also a substantial lower grade resource delineated to the south of the main orebody. These remaining ore sources present significant engineering challenges to obtain a safe and cost-effective extraction. Stope designs have become increasingly complex and require additional engineering and operations input and analysis. This paper describes the major planning and operational challenges and issues associated with the stope design and extraction of an orebody in the later stages of mine life.

Jan 1, 2000

By Jong-Ren Tarng, Gin-Hwa Chen, Wen-ku Chang, Ke-Ming Lin, Yuan-Haun Lee

"The majority of early studies used X-ray diffraction, but this requires a model to interpret the diffraction processes. A turbostratic model has been applied by Warren, Franklin and Bacon to a wide range of materials including both soft and hard carbons. Maire and Mering applied the same methods to the interpretation of the (001) lines of a series of graphitic carbons. In our case, graphitic carbons undergone high temperature and high pressure graphitization processes have been evaluated by the same methods. It were found that most technological XRD data were obtained by a Rietveld method with the least-squares refinements could be in the simplest way since the full correction technique is very laborious. The behavior of carbon materials as it proceeds through the graphitization process is characterized by changes in the measured interlayer spacings (d) a~ a function of temperature. A series of graphitic carbons including the transformation of diamond to graphite through the process under high temperature and high pressure have been evaluated. A simple calibration equation has been established. IntroductionRecently, in battery industry, carbon materials are used as cathode in lithium ion batteries. However, graphitization of those carbon materials is concerned as if lithium ion intercalated into those carbon cathode. Both high-graphitization and low-graphitization carbon materials are suitable for this kind of application.As for graphitization, the starling materials from which carbons may be prepared vary extensively from pure chemical compounds, to mixtures containing II wide range of molecular weights, such as pitches. So its graphitizing, perhaps the most notable feature of the process, is the very wide range of temperature over which the perfection increase, unlike the more common transformations of solid state materials which occur in a narrow temperature range. The variables involved in the conversion of the initial hydrocarbon to a carbon residue, which may vary widely in final perfection, are time, temperature, stress and impurity content"

Jan 1, 1996

By Zhihe Dou, Jiang Liu, Ting-an ZHANG, Yukun Huang

The paper aimed to propose that mixed rare earth concentrate was decomposed by pressurized calcification where mechanical milling was applied simultaneously (also known as mechanochemical calcification). The bastnaesite and monazite were both decomposed by OH−, where released rare earth formed RE (OH)3, released fluorine and phosphorus formed CaF2 and Ca2P2O7. Then, the calcified slag was leached by diluted hydrochloric acid to extract rare earth and both recover fluorine and phosphorus. The phase transformation regularity, the behavioral trends of rare earth, fluorine and phosphorus were investigated. Results showed under the optimal conditions of ball to material weight 80:1, the calcification temperature 250 °C, the liquid-solid ratio 5:1, the leaching yield of rare earth reached to 92.16%, Ce was 86.47%, La was 97.58%, Nd was 99.99% and the mass fraction of F, P entering into calcified liquor were 8.27, 0.21% respectively. The micromorphology of the mineral has a transition from dense to fluffy, and then became dense again.

Mar 1, 2018