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By J. H. Hodgson

"Those of us who have been concerned with the problem of geophysical exploration in southwestern Ontario have followed the development of the Poulter method with much interest. I have much appreciated the opportunity of reading an advance copy of Dr. Poulter's clear exposition and of preparing the following brief remarks on the probable applicability of the method to the Palaeozoic area of southwestern Ontario.During the years 1944 to 1946, the Ontario Department of Mines, in co-operation with the Union Gas Company and the Dominion Natural Gas Company, operated an experimental party in the hope of establishing a seismic technique appropriate to the •area. The results were completely negative. During two summers' field work, no reflections whatever were obtained except in one area near Windsor. It is the •purpose of these remarks to inquire whether Dr. Poulter's techniques might yield favourable results.It was the conclusion of the report on our work that two principal causes contributed to the failure of the method. In the first place, the geological column possesses few elastic discontinuities and those that exist appear to have low reflection coefficients. In the second place, the area is drift-covered in general. This drift complicates the situation by absorbing seismic energy and by giving rise to groups of complicating refracted phases which obscure the entire interesting section of the record. The situation is further complicated by the high reflection velocities and the relative shortness of the Palaeozoic section, these factors combining to bring in a reflection from the basement in about half a second."

Jan 1, 1950

By P. Scinto, P. Hudson

"Modern day ore bodies are becoming increasingly harder, more abrasive and lower grade. The Mako deposit is located in Senegal and consists predominantly of primary mafic and felsic lithology that are both very competent and very abrasive ores (Axb < 30, BWi >20 and Ai >1.0). The deposit was initially discovery in 2010 and the Toro Gold management team fast tracked the Mako Project through development and into production to achieve its first gold pour in January 2018. The comminution circuit comprises primary crushing single stage SAG milling with recycle crusher (1oCR SS-SAC). The mill reached design throughput and grind size seven weeks after first ore. The Mako project marks another successful international application of single stage milling, which represents a simple and easy to operate comminution circuit for small-to-mid size projects with a low capital cost. This paper describes the ore interpretation, comminution modelling, grinding circuit selection and design, as well as an overview of the commissioning and ramp-up of the mill.INTRODUCTION The Mako Gold Project is operated by Toro Gold Ltd., which holds a 90% interest in the project. The project is located in south-eastern Senegal in the Kedougou region, close to the Gambia river and township of Mako. The Mako deposit lies in the “Kenieba Window” of eastern Senegal and western Mali, which hosts a number of gold mining operations and development projects. The Mako Gold Project has an estimated life of 8 years with overall recoverable gold estimated at 924 koz. The process plant is designed to treat 1.8Mt/a of ore and produce 128 – 143 koz of gold per annum. Lycopodium Minerals Pty Ltd (Lycopodium) was appointed to provide feasibility studies and EPCM services for the greenfield project. Forming part of consultancy services provided by Lycopodium, Orway Mineral Consultants (OMC), a subsidiary of Lycopodium, was involved in the design, commissioning, ramp up and ongoing post commissioning support of the comminution circuit."

Jan 1, 2019

By Nicholas C. Williams

This paper presents the development of a demand reduction and responsive strategy capable of reducing the electrical power demand, particularly during peak conditions. The work presented includes a case study of a UK colliery. Areas explained are the equipment installation at the mine; the development of the demand reduction strategy including the load profile database and prediction optimisation model. Some live production data from the power meter installation at the mine is also presented.

Aug 1, 2013

By Charles G. Kemsley

MR. C. R. WHITTEMORE: It is interesting to note that the mining industry is making increased use of alloy steels for drilling. They will undoubtedly lead to greater footage at lesser cost. Mr. Kemsley states that, for use in hard ground, the shanks are brought to a hardness of 435 to 440 Brinell by heating them to approximately l,800°F. It seems to me that this temperature is excessively high-it is considerably above the critical point of the steel. The only effect of such a high temperature is to lessen considerably the impact resistance of the steel. The possibilities of an oil quench, followed by a tempering draw which does not lessen the hardness of the steel too much but increases its toughness, might well repay further study; also the temperature control, a factor which depends on the composition of the steel. However, service results are undoubtedly the best criterion of practice. MR. KEMSLEY: I would like to point out that the steel is not quenched at 1,800°F. After heating to this temperature, it is laid aside to cool gradually; this high temperature is necessary to produce the required hardness by simple normalizing-cooling in still air. We all know that ideal conditions for hardening steel demand salt baths and furnaces with automatic temperature control, but for most companies the cost of such equipment having sufficient output capacity is prohibitive. The end we are trying to attain is to make good drills at a cost that will be within the means of any mine.

Jan 1, 1942

By John B. Phillips

The mine is entered by a central vertical shaft, strongly timbered, and containing two compartments-one for the passenger cage, the other for the large skips bringing the ore to the surface. A man-way, for emergencies, is also provided, parallel to the shaft. The cage is a single-deck steel box, carrying about thirty persons; by means of arrangements above and below, it can also hoist and lower materials needed in the workings. Levels are run at intervals of 100 feet. In special cases, where the ore conditions warrant, sub-levels are operated, such as those at 1,113 feet and 1,123 feet (Fig. 7), which are connected by winzes with the 11 th level. One of these was pushed for 40 feet, and then abandoned because it was unprofitable to take up ore of the grade encountered. The ore between levels is removed by stoping. The drifts follow the course of the veins as much as possible, with numerous cross-cuts. Winzes, raises, connections, etc., are blasted out where needed. The main drifts are at least 8 ft. high by about 9 ft. wide. All former narrow drifts had to be widened some time ago, by ruling of the Ontario Department of Mines, to lessen the danger of accidents with cars in the small passages. Accurate plans of the under-ground workings are kept in the office, and extensive surveying is always being done underground to keep the maps up to date, measure the cubical contents of stopes, and so forth. Timber is extensively used in the construction of supports and chutes, and in the sinking of the shaft. Steel and concrete are too ex pensive to compete with timber, which 1s abundant in such sections as have escaped forest tires.

Jan 1, 1926

By G. H. McKay

AT the Eagle mine, near Gilman, Colorado, where the Empire Zinc Company have installed an underground mill, transportation problems were comparatively simple. A railway siding on the Denver and Rio Grande railway is equipped with an unloading dock or platform at the portal of their service incline adit to the mill. This 18-degree incline is approximately 600 feet long from the unloading track to the head of the mill skipway. For the Big Missouri mill, upwards of 2,500 tons of material and equipment had to be trucked from tidewater at Stewart, B.C., a distance of 21 miles to the Big Missouri camp at elevation 2,800. From that point, this freight had to be moved either over or through the Big Missouri ridge, rising to elevation 3,450, to its final location 800 feet from the surface between elevations 2,150 and 2,350. Immediately after leaving the government dock at Stewart, the road crosses the International boundary line into Hyder, Alaska, and then follows a water grade for eleven miles along the lower stretches of the Salmon river. leaving the river, the road climbs for two miles before crossing back into British Columbia territory at Silver Heights, and then continues for another mile and a half to where the Big Missouri road branches off from the main road to the Premier mine. For a distance of four miles from the junction of the roads, the Missouri road is very narrow, with many sharp curves and with irregular up and down pitches and grades up to 25 per cent until it reaches the Summit. From there on, a fairly easy grade leads a mile and a half to the end of the road on Joker Plats. In winter, the last stretch of road is subject to heavy snow drifting, especially through a narrow funnel-shaped gulch, known as &apos;The Gap&apos;, where the snow may pile up to a depth of over twenty feet.

Jan 1, 1938

By G. Vibert Douglas

NICKEL minerals are known in New Brunswick but have never been reported from Nova Scotia. The attention of the writers was drawn to an occurrence of pyrrhotite, reported to carry nickel, at the Second Gold brook, Middle river, Cape Breton. The purpose of this paper is to record the occurrence and give an account of the general geological association. In a later paper it may be possible to give greater details? than are available at present. GEOLOGY The area lies at the edge of a plateau of Precambrian rocks which forms the panhandle of Cape Breton island. This plateau has a general elevation of 1,200 feet. Middle river, with its tributaries, the First, Second, and Third Gold brooks drains the area. The lower country to east and southeast of the plateau is underlain by lower Carboniferous sediments. The rocks of the plateau are presumably of Precambrian age but have never been definitely correlated with the Gold-Bearing Series of the mainland. ?There i:s; however, some resemblance, although they have apparently been more intensely mountain-built. They are essentially fine grained, sheared quartzites and slates . The general strike is east and west, with a north dip of 45° to 55°. There are smalllocal drag-folds in the area. The only igneous rock in the immediate vicinity is an intrusive pink porphyry. It has small phenocrysts of quartz and feldspar. It has intruded the sediments generally along the structural planes, but in places crosses the structure . Its intrusive character is further proved by the fact that it contains xenoliths of the quartzite.

Jan 1, 1937

By Sh. Karimidorabati

In the construction industry, project changes constitute a major cause of delay, disruption, cost increases, poor quality and unsatisfying performance. They are also known as a main factor of litigation between the owners and constructors. Construction projects are essentially process-based, and with the critical role of Information Technology (IT) in this industry, projects, especially mega projects, are being managed remotely. The volume of data and documents, such as Requests For Information (RFIs), different types of Change Requests (CRs) and Project Change Notices (PCNs), being transferred and exchanged amongst the stakeholders of a project is considerable. The circulation of these documents amongst project stakeholders still heavily relies on two methods or levels for management of change process; Conventional (fully paper-based, Faxes, Snail mails) and Electronic or semi-automated (Email, Internet, PDF files). These two methods are dependent on human discipline to follow specified processes which often break down because of human nature. This creates serious compliance problems. It is hypothesized here that fully that automated process-based management of change can lead to better compliance, more efficient management of change, and reduction of time and cost of data exchange. An approach of doing this is presented in this paper. Ultimately, its impact should improve project performance. Conclusions are presented on time savings and improved compliance.

Aug 1, 2013

By P. Burke, V. Vuaroqueaux, A. Doyle, C. Petit, Kipouros. G. J.

Magnesium and its alloys are attractive for use in automotive and aerospace applications because of their low density and good mechanical properties. However, difficulty in forming magnesium and the limited number of available commercial alloys limit their use. The present work reviews the efforts to improve the attractiveness of magnesium through non-traditional processing, and presents results of current work on producing magnesium alloys via powder metallurgy (P/M). P/M can be used to alleviate the formability problem through near-net-shape processing, and also allows unique chemical compositions that can lead to new alloys with novel properties. The surface layer formed on the Mg powders during processing acts as a barrier to diffusion and sintering is problematic. The layer contains oxides, hydroxides and carbonates of magnesium, formed by reactions with the atmosphere. There are several means to possibly overcome this barrier. Alloying additions have been identified that may promote surface layer disruption during sintering. Processing variables such as sintering atmosphere may reduce the layer or allow the formation of less detrimental compounds. Post-sintering processes such as hot working may disrupt the layer and improve density. The experimental effect of all these processing parameters is presented in this paper.

Jan 1, 2010

By A. J. Baer

"DEFINITION OF THE REGION AND ITS BOUNDARIESTHE EXPOSED PART OF THE GRENVILLE PROVINCE is the southeastern part of the Canadian Shield, characterized by crystalline rocks with K-Ar ages of about 1,000 million years. Its Canadian portion is bounded on the southwest by Georgian Bay •and by Paleozoic sediments south of a line passing through Orillia and Kingston, on the southeast by the St. Lawrence River valley and the north shore of the Gulf of the St. Lawrence, on the east by the coast of Labrador and on the northwest by the Grenville front, a linear tec-tonic feature that is a metamorphic transition zone and/or a fault. Rocks located to the southeast of the front have younger K-Ar radiom€tric ages than rocks located to the northwest of it.The region is formed of complexly deformed and highly metamorphosed crystalline rocks and in part differs from other areas of the Canadian Shield by the presence of large amounts of crystalline limestone and bodies of anorthosite."

Jan 1, 1970

By Ray Collier

MINING TODAY l EXTENSIVE AND EXPENSIVE PERMITTING PROCESSES WITH UNKNOWN RESULTS l GENERAL AND IMPASSIONED RESISTANCE TO RESOURCE BASED INDUSTRY l SOPHISTICATED, ORGANISED, AND WELL FUNDED OPPOSITION l MOST LOCAL GOVERNMENT DOESN?T WANT MINING TODAY?S TALK l FOUR SPECIFIC OPERATIONS ON WHICH OUR EXPERIENCE IS BASED ? SECHELT ? CADMAN ? GRANVILLE ISLAND ? LEHIGH CEMENT DELTA PLANT l OUR APPROACH TO COMMUNITY RELATIONS

May 1, 2002

By G. Bonin, R. P. Preston

"This paper presents a series of case studies where spherical camera photographs were used to generate 3D shaft models using photogrammetric methods. The shaft models were, checked for accuracy by comparing them to overlapping laser scan data, provided survey data or idealized shaft models. Short lengths of model were found to more accurately reproduce the shaft surface, with a best observed accuracy of 8 mm. Longer models encountered errors with accumulated errors as exhibited by slight deviations from vertical or slightly conical model shape. At present, the models are considered acceptable for general documentation and gross change detection. INTRODUCTION Shaft inspections are required by mining regulations in many jurisdictions and are commonly completed by trained mine personnel via visual inspections. This can be time consuming and prone to errors due to lapses in attention and the rapid travel rate required to inspect an entire shaft in a reasonable amount of time. Similarly, because of the time requirements, there can be impacts on other aspects of mining as a result of occupying the shaft for inspections. Spherical cameras with supplemental light systems offer a modern addition or alternative to conventional inspections. These cameras can be lowered relatively quickly to collect high definition, fully illuminated videos of the shaft that can be reviewed in detail later while the shaft returns to service (Gillis et.al., 2019). The use of cameras offers a further opportunity for valuable survey data generation from the same original data stream. The video data can be processed into three-dimensional (3D) models using Structure-from-Motion (Westoby et al., 2012) based photogrammetric methods. Depending on the quality of the source video and availability of survey control (required for all photogrammetry models) these models can be very accurate. Shaft surveying can be conducted with traditional theodolite methods but such surveys are time consuming and limited in their data density. Similarly, scans can be completed using conventional terrestrial laser scanners, but this requires a significant number of distinct setups to provide sufficient overlap between scans. Work is being conducted both on the laser scanning (SLAM, Durrant-Whyte & Bailey, 2006) and photogrammetry fronts towards kinetic scanning (Benecke, 2017) systems. The major advancement which is permitting these kinetic systems is Inertial Measurement Units (IMUs) which can provide localization in GPS denied environments and reduce errors associated with the open traverse format associated with shaft scanning."

Jan 1, 2019

By W. Jomaa, V. Songmene, O. Mechri, Laval Université, P. Bocher, J. Levesque

"A 2D finite element modelling (FEM), based on pure Lagrangian approach, is developed for studying the serrated chip formation during high speed machining (HSM) of 7075-T651 alloy. The solution was achieved using a commercial software package, ABAQUS/Explicit v6.13. The Johnson-Cooke (JC) constitutive equation is used to describe the work material behaviour. Moreover, the JC damage equation is implemented into the FEM to take into account for the shear localization during the serrated chip formation. Modified Coulomb friction model has been used to characterize the sliding/sticking effects on the tool-chip interface with the friction coefficient and shear flow stress determined by force calibration and machining data, respectively. The proposed FEM is validated using experimental data obtained in HSM of 7075-T651. The FEM was able to predict accurately serrated chip morphology. The intensity of chip segmentation was found to increase with cutting speed.INTRODUCTIONHigh speed machining (HSM) is one of the most used processes for manufacturing aircraft parts with aluminum alloys. For aluminum alloys, the use of HSM increases metal removal rate and reduces the formation of built up edges and burrs. However, it was found that serrated (also named segmented or sawtooth chip) and discontinuous chips can be produced during HSM of some high strength aluminum alloys, such as 7075-T6 alloy (Rao & Shin, 2001). Many parameters were found to affect the segmented/discontinuous chip formation during the machining of aluminum alloys.There are two cases in which the serrated chip can forms: the first is when machining hardened materials (Morehead, Huang, & Luo, 2007), and the second, when machining ductile materials with a cutting speed higher than a critical value (Barry & Byrne, 2002). Different theories and models were developed in order to explain the formation mechanism of such kind of chips. According to Astakhov (2006), the segmented chip formation is attributed to variations in stress and plastic deformation states, and resulting temperatures on the cutting zone. Liyao et al. (2013) stated that the segmented chip formation was mainly attributable to adiabatic shear instability/catastrophic strain localization. Others (Vyas & Shaw, 1999) suggest that the fracture/crack propagation mechanism is at the root of chip generation."

Jan 1, 2016

By C. Cristonffanini, S. Nazari

"In the past, simulation was considered to be an offline tool disconnected from plant operation. Advancements in the computation power combined with utilizing physics and chemistry sciences have allowed us to significantly improve the modeling and simulation technology for mining and mineral processing. This paper investigates the benefits of first principle models and simulation by connecting them to real time operation. Process data are connected to high fidelity models executed in parallel to the operation. In recent literature, this concept is known as Digital Twins. The Digital Twin is used for various purposes such as optimization, virtual instrumentation and condition monitoring. Using IDEAS™ simulation software we are able to construct a digital twin for different equipment inside a mineral processing plant. Two case studies for building a digital twin for the primary hydrocyclone feed pump and thickener underflow are presented. Using the pump’s model, a digital twin is developed and is installed in a gold extraction plant that is able to infer the slurry density in real time. Additionally, it is used for detecting sanding in the pipes and impeller condition monitoring.INTRODUCTION Since the eighties, thanks to advances in computation technologies, computer based simulation of processes using first principle models has become a well-known engineering tool for various industries. As our understanding of processes has increased, their representative models have become more realistic and more sophisticated. Due to this increase of accuracy, use of simulation is becoming more fundamental in process industries. The main goals to use accurate simulation is to decrease the engineering and construction cost, optimize the process design and improve the operation performance by decreasing operation cost and increasing efficiency. The term Digital Twin was first introduced in 2010 by NASA (Shafto et al., 2012) in aerospace industry. Subsequently, the concept quickly spread through other industries. As of today, no standard organization has provided an official and unique definition of Digital Twin for process industries. However, there are three important aspects that are common throughout various descriptions. When simulation is core functionality of the process (1) along the entire life cycle of the plant (2) with direct linkage to operation (3), it is called that process has a Digital Twin. According to Gartner, the concept of Digital Twin has elected as fourth most important disruptive technology for the year 2018 (https://www.gartner.com/, 2017)."

Jan 1, 2019

By W. A. Green

To those who may not be familiar with the history and organization of the Flin Flon mining property from the rime of its examination and option by the Harry Payne Whitney interests until the present start of operations by the Hudson Bay Mining and Smelting Company, Limited, this paper may give a better understanding of the property. More technical discussions are being presented to you by the men most closely connected with the various operations of the property. Location The Flin Flon mine is situated along the boundary line between the Provinces of Manitoba and Saskatchewan at approximately. 54° 45? north latitude, but largely in Manitoba. Prior to the advent of the railway, the property was quite isolated. The summer route was over a course of some 175 miles, consisting of a 125-mile boat trip from The Pas, first up the Saskatchewan river, then across Cumberland and Sturgeon lakes to Sturgeon? Landing. From Sturgeon Landing, a .16-mile portage was necessary to Camp 2 on lake Athapapaskow. From Camp 2 the route consisted of a canoe trip of 32 miles across lake Athapapaskow, up the northwest arm of Schist lake, then up Ross creek to the Company&apos;s docks, and finally a 2-mile walk to the property. The winter route was just under 100 miles in length, the difference being due to the fact that a more direct route could be followed over the frozen lakes. It went up the Saskatchewan river for a short distance above The Pas and then, leaving the river, the road followed Reeder, Rocky, and Sturgeon lakes to Sturgeon Landing, and from there over the same route as the summer one, only across the frozen lakes.

Jan 1, 1930

"The content of production reports has its origins in raw measurements taken in harsh production environments. The ensuing measurement/estimation errors always affect reproducibility such that, regardless of the fact that they are balanced through statistical data reconciliation, reported numbers are simply the most probable values of inferred probability distributions. This has important implications for how metal recoveries should be monitored and reported. Indeed, in a context where many process optimisation activities are based on small improvements in recovery, there should be no doubt that inadequate handling of measurement/estimation errors can easily exaggerate or mask actual changes in process performance. However, estimates of the reproducibility of reported metal recoveries are rarely reported to plant management. This situation persists despite the fact that a code compliant metal accounting system must inform management about business risks related to metal accounting. To this extent, this paper focuses on the continuous management of reproducibility level of metal recoveries in compliance with the best practices. Sensitivity analysis of primary and secondary metal accounting models is performed to show the resulting probability distributions for metal recoveries. Some guidelines are given for designing and managing metal accounting systems capable of achieving and sustaining predefined levels for the reproducibility of metal recoveries.INTRODUCTIONEach and every mineral processing plant produces daily, weekly and monthly production reports in which metal balances for payable and penalty elements are presented. While such production reports are usually consulted in offices, underlying raw measurements are taken in harsh production environments where mechanical vibrations, humidity, corrosion and dust, to name a few, disturb measurement procedures. It is thus no surprise that several authors (Francois-Bongarcon & Gy, 2002; Gaylard, Randolph, & Wortley, 2014; Holmes, 2010; Spangenberg & Minnitt, 2014) have reported pervasive issues related to mass/sampling measurements in the context of mineral processing."

Jan 1, 2016

By Hazel Lyman Nickel

Daring to try where others had failed, Herbert and Lou Henry Hoover translated from the Latin the principal (and first) textbook on the mining and metallurgical profession, De Re Metallica, 1556, which had been in use for two centuries and then had lain dormant for 350 years in a language unreadable except by a chosen few. Thus the Hoovers enriched the English tongue with a vitally important contribution to history in the fields of mining, metallurgy, and chemistry. To them it was a joint hobby, because they were actively interested in the beginnings of the mining profession in which they had both been trained. Illuminating the years of toil to perfect this translation shone their ideal of service to humanity, since, in the Preface, they refer to their task as "a labour of love", which had to find the moments for its execution in night hours, weekends, and holidays, extending over a period of about five years. And they add: "If the work serves to strengthen the traditions of one of the most important and least recognized of the world&apos;s professions, we shall be amply repaid". While a student at Stanford University, during the years of 1891-95, Herbert Hoover had become familiar with a copy of this Latin mineralogy classic, De Re Metallica, a rare book in the private library of Dr. John C. Branner, at that time head of the department of geology and mining. Another Stanford student in geology was also examining and studying the ponderous volume of twelve &apos;books&apos;. She was Miss Lou Henry, of Monterey, who graduated in 1898, and the following year became Mrs. Herbert Hoover. Interwoven through the tapestry of their life experiences gleamed the silver thread of their interest in this mediaeval Latin textbook. Just nine years lacer, the Hoovers had commenced their translation, while they were in temporary residence in London after the seething years in China under the shadow of the Boxer rebellion.

Jan 1, 1949

By M. Lindgren

"Hydrometallurgical processing involves process stages, like leaching, that create harsh environment for stainless steels. High acidity, the presence of chlorides and oxidizing ions combined with relatively high temperature create risk for both uniform and localized corrosion. Advanced electrochemical techniques were employed to study uniform and pitting corrosion of two stainless steel grades 316L and 2205. Results obtained with the linear polarization resistance technique combined with the harmonics distortion analysis, electrochemical noise and coupled multielectrode array systems are compared to the results of conventional electrochemical techniques and immersion tests.INTRODUCTIONHydrometallurgical processing has become favoured in metals production in recent years due to energy costs, leaner ore bodies and environmental factors. Because the hydrometallurgical processing route is flexible, various types of secondary raw materials, like flotation tailings, dusts, sludges and slimes can also be treated in addition to conventional mineral concentrates (Sarveswara Rao & Acharya, 2008).Hydrometallurgical processing relies on aqueous chemistry, usually acids, at temperatures around 100°C for the recovery of metals from ores, concentrates, recycled or residual materials. The processing route can typically be divided into three stages: leaching, solution concentration/purification and metal recovery. The processing environment is aggressive, especially in leaching. High acidity, relatively high temperature together with impurities, like chloride ions, place high demands on the corrosion resistance of construction materials. The dominant corrosion mechanism may be uniform corrosion or localized corrosion depending on the process conditions (Ekman & Torsner, 2010). This complicates the prediction of corrosion rates and, consequently, cost effective material selection.Traditional means to evaluate uniform corrosion resistance of stainless steels are immersion tests and the results are published in the form of iso-corrosion diagrams (Outokumpu Stainless, 2010). For the localized corrosion, namely pitting and crevice corrosion, immersion tests can be used but the duration of the test is rather long because an incubation period takes place prior to the occurrence of the actual localized corrosion damage. Electrochemical techniques, traditionally in the form of cyclic polarization scans, have been employed to assess the susceptibility of a material to pitting corrosion (Papavinasam, 2008). They cannot, however, give any indication of the pitting corrosion rate and lack potential for on-line measurements."

Jan 1, 2012

By X. M. Zhou, T. Wu, He X. N.

"In order to study the support effect of concrete in the surrounding rock of a metal mine, the concrete and surrounding rock were comparatively studied. Firstly, the general situation of the ultra-kilometer deep shaft in Xincheng, surrounding rock and geological conditions are introduced. Secondly, the experimental scheme of material mechanical properties of surrounding rock and shaft lining concrete based on same standard dimension and shape are examined, and the mechanical tests of rock and concrete based on different shapes and sizes are carried out. The study shows that the compressive strength value and elastic modulus of the rock cube are 1.28 times and 1.78 times that of the cylinder, and the Poisson's ratio is 0.77 times. The dimensional effect law of the concrete cube and cylinder test data is consistent with the rock law. However, the test results of the concrete are less discrete than the rock; the test also shows that the strength and elastic modulus of the concrete lining of the main shaft of the Xincheng are much smaller than the surrounding rock that is also used as the concrete aggregate, which indicates that the support of concrete lining in the surrounding rock shaft behaved weakly. Based on the development of the modern NATM rock support theory, it is suggested that the mechanical test standard of artificial support materials should be unified into the mechanics test standard of natural rock, which will help to improve the accuracy and practicality of scientific calculation of geotechnical engineering.INTRODUCTIONConcrete and rock mass are usually attributed to a class of materials called frictional materials or geotechnical materials, of these two kinds of materials, the first is man-maded and the second is natural. The attentive scholar can find that there are many differences in the test criteria for the mechanical properties of the two kinds of materials among different industries or departments, reflecting the differences in their sources, tradition, and the application thoery of material strength among them.There is a situation wordwide, that there are many testing standards of the same material mechanical parameters such as elastic modulus, compressive strength, etc. The cube with a side length of 150 mm is adopted as a common sample in the architecture department in China, while a cylinder with a diameter of 50 mm and a height of 100 mm is as a standard specimen in geotechnical department.Knowing that mechanical parameter values are strongly affected by the the size, shape of specimen and loading rate etc, that is to say the mechanical parameter values of the same material are completely different when obtained from different test with different standards. However, such a problem has been long neglected in geotechnical engineering."

Jan 1, 2019

By J. A. Ressinger

"The purpose of this paper is to discuss some of the differences between various methods of excavating and loading as they relate to mining operations. The intent is not to provide ""pat"" answers, but instead to raise some questions and set forth some reasonable guidelines.Specifically, the paper deals with the differences and relative merits of power shovels versus rubber-tired front-end loaders - or, carrying this further, comparing what could be called ""stationary"" loading or excavating devices to ""mobile"" types."

Jan 1, 1972