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By YUSONG MIAO, DI WU, XIANRONG YAN, YIPING ZHANG, JIE LIN, KEBIN LI

Rock fragmentation has been a concern in hard-rock mining for the mining industry. Rock fragmentation distribution is an important index to measure the blasting effect. It not only affects the cost of drilling and blasting, but also affects the efficiency of subsequent operations, such as loading, transportation and secondary crushing.

When I reached Warren after the "de luxe" South American expedition I had little idea what was in store for me. From the large check Thayer had handed me just before I left New York I was pretty sure the future would be good, and that before long it would involve Anaconda. Evidently, Mr. Thayer had left it to Dr. Ricketts and John Greenway to work out the details The next morning Greenway asked me to come to his office and told me that he and Dr. Ricketts had discussed the question and that Anaconda would make me an offer I could not refuse. They proposed to pay me almost $1000 a month, more than twice my current salary. They had agreed that I should stay with Calumet and Arizona for the rest of the year to help with Bisbee development and anything I could to assist with the New Cornelia plans and construction Of course I could not turn down such a flattering offer, as I had about reached the limit of advancement with a much smaller company in anything save a high executive job, and it would be a long time before I could be ready to change from exploration and geology to operating. Greenway and I agreed that I would stay with him for the remaining eight months of 1916 without any particular title but helping in any way I thought would be most useful. Bisbee and Ajo Study It turned out to be a busy half year, in addition to many good times with my Bisbee friends. The Uplift Club did not meet as regularly as in earlier years, but Mason Ross, Jim Lewis, Bill Gohring, Roy Mitchell, Hubert d'Autremont, Arthur Notman, and I did have many "bull sessions" and poker games. I saw much more of Greenway than before and made many trips with him to Ajo and later to the new

Jan 1, 1976

By W. V. Liu, D. Omane, H. Yu, Y. Pourrahimian

"A large-scale wildfire had broken out at Fort McMurray in Alberta, Canada during May 2016. Many oil sands mining activities were affected due to the wildfire and the associated ash emissions. In particular, ash emission generated from the fire outbreak is a huge problem during the post-fire cleanup. These emissions pose a severe health hazard to workers, environment, and global climate. The ashes emitted into the atmosphere are caused by either human activities or climate conditions. The objective of this research is to assess the effect of three different ash dust suppressants, namely water, #1 surfactants, and #2 polymers at various volumetric concentrations on ashes samples to prevent propagation of fine solid emissions into the atmosphere. It is found that both #1 surfactants solution and #2 polymers solution are effective in retaining fugitive ash dust generated from the ashes. Volumetric concentration efficiency of 0.05% of #1 surfactant and 5% of #2 polymers in 500 ml of water have been proven to provide ash dust retention efficiency greater than 99% after the spraying of these suppressants. It is also found that both #1 surfactants solution and #2 polymers solution maintain an ash dust retention efficiency higher than that of the use of only water. This confirms the merit of using chemical dust suppressants on fugitive ash dust for a longer period, which is proven by the 72-hour data from this experiment. This study gives a general view of how effective chemical suppressants on fugitive ash emissions work. INTRODUCTION On May 1st, 2016, a large-scale wildfire gutted Fort McMurray, Alberta, Canada. Many oil sands mining activities were affected due to the wildfire and the associated ash emission. Due to the wildfire, some of the biggest oil sands companies in Fort McMurray such as Royal Dutch Shell and Suncor Energy shut down their oil production, at 255,000 and 350,000 barrels per day respectively [1]. Syncrude Canada Ltd scaled down its normal production capacity level of 350,000 barrels per day [1]. This generated an estimated loss of about 1.1 million barrels of oil production per day, constituting a 30% reduction in the Canadian daily oil production, crippling the economy [2]. This loss in production by the companies translated into 0.33 % of the Alberta GDP in 2016 constituting a loss of $985 million and 0.06 % of the entire Canadian economy [3]. In 2017, it is estimated that the rebuilding and reclamation of the affected areas in Fort McMurray will add $ 1.3 billion in GDP to Alberta’s economy [3]. A population of over 90,000 people was evacuated from the location and its surroundings for health and safety reasons [4]. The fire destroyed about 2,400 structures and over 500,000 hectares of forest vegetation in Fort McMurray, leaving an estimated 232,000 tonne of post-fire ashes [5,6]."

Jan 1, 2017

By James E. Lawver

During 1981 the Florida phosphate industry produced more than 43 million metric tons of phosphate rock - about one-third of the entire world production and also generated nearly an equal amount of waste clay and waste clay-sized product that requires dewatering and disposal. The material balance of solids and water for a typical Florida phosphate mining operation is shown in Figure 1. Historically, the industry has impounded clay waste (about 60% below ground and 40% above ground) in earthen dams, often as large as 800 acres and occasionally greater than 60 ft. high. The dams have served the triple purpose of: 1. Dewatering initial 3% solid waste clay for process water re-use. 2. A reservoir system to minimize water discharge from the mining area and to capture and store rainwater thus minimizing deep well pumping requirements. 3. The ultimate densification and storage of waste clay.

Jan 1, 1983

By Lawrence Lien

The reduced need for traditionally trained and educated personnel in the mining industry is systemic to the changing mining industry. Universities and other training institutions are meeting the traditional skill needs required by the industry, but are the skill needs going to be the same in the near future? The answer may be no. Mining is changing because of increased liabilities and costs of environmental and safety is-sues; lower grades of minerals in traditional mining activities and the advent of new bio-chemical processes and robotic equipment. More productive and economic alternatives, and larger, more sophisticated and automatic equipment, are also changing the industry. Engineering is more specific, accurate, precise and expensive. Measurement is more thorough and timely of progress, production, costs and productivity. And, the industry will likely be engaging in more undersea mining, possibly space-based processing, less human interaction and more remote control of events than was previously thought possible.

Jan 1, 2011

By G. V. Sullivan

As part of its program to conserve domestic mineral resources through advancing mineral resources technology, the U.S. Department of the Interior, Bureau of Mines, conducted investigations to determine the feasibility of recovering high-grade barite concentrates, suitable for use as well-drilling mud, from current and old waste pond materials and materials bypassed in present mining operations. Flotation studies of waste pond samples from Missouri and Nevada yielded barite concentrates containing over 95 percent BaSO4 with recoveries of 86 percent and 96 percent, respectively, of the barite in the flotation feed. Flotation studies of a hard-rock sample from Georgia, currently bypassed in mining, yielded a barite concentrate containing 97 percent BaSO4 with an attendant recovery of 97 percent of the barite.

Jan 1, 1980

By F. D. Huntley

Raw materials used by the Flat Glass Industry are known in the Industrial Minerals geology sector as Specialty Products. These pro- ducts must meet specification limits usually not the same for all glass manufacturers. Evolving new glass compositions will require mineral concentrates of consistent purity being produced within economic limits that will assure market viability of the resulting glass product. The amount of success the Flat Glass Industry will achieve by developing and maintaining domestic production centers will be determined by many economic factors which affect the costs of doing business. Technological developments by mineral processors must continue in order to achieve more efficient production of high quality glassmaking raw materials.

Jan 1, 1986

By Baolin Qu, Jingxin Wang, Cuncang Xu, Bing Wu, Mingyu Zhong

With the development of the coal mine regulation regime, the situation of coal mine safety production in China has continued to improve. However, coal mine accidents have not been fundamentally eliminated; constantly learning from historical accidents can make mining work safer. Therefore, to better understand the coal mine accident characteristics, this study analyzes the tendency of coal mine safety accidents from multiple perspectives, among which all accidents after the establishment of the State Administration of Coal Mine Safety in 1999 are the top priority. The results show that strict national policy, technological progress, and reasonable coal prices are conducive to the safe development of mines. On the contrary, high-intensity centralized production will lead to frequent accidents in the peak season of coal production. In addition, the type of coal mine ownership will have an indirect impact on the occurrence of coal mine accidents. The research results not only play a positive role in the prevention and control of coal mine accidents in China but also have reference meanings for the safety production of coal mines in other countries in the world.

Dec 28, 2022

By Ronald F. Ayers

The study upon which this paper is based was completed by Battelle's Columbus Laboratories for the U.S. Army Corps of Engineers in 1974. It is but part of an overall effort by the Corps to evaluate the costs and benefits to the nation of waterway improvements. This study is primarily concerned with future coal markets for production from those counties near the Wabash River in the heart of the Eastern Interior Province. An objective here is to consider a most pessimistic energy (and hence, coal) demand for planning purposes.

Jan 1, 1976

By Elnaz Saminfar, Jae Bateman, Eric Westergren, Mark Trim

This paper presents a case study of two major Australian infrastructure projects that used digital engineering to facilitate design delivery: WestConnex Project (Rozelle Interchange), and Sydney Metro West (Eastern Tunnelling Package). The paper presents project overviews and building information modeling (BIM) execution and focuses on modeling techniques, software utilization, data management strategies and how the digital models helped the design-build team mitigate impacts to schedule by identifying clashes between disciplines before the execution of work. Finally, it demonstrates the positive and transformative impact of digital engineering on the design and construction of large underground infrastructure projects and highlights its role in asset management throughout the project lifecycle.

Jun 23, 2024

By Walter E. Kramer

The advantages derived from the use of pellet burdens in blast furnaces are so great, that hematite ores are being converted into pellets in greater quantities each year. The conversion of these ores into pellets appears on the surface to be relatively simple. In reality, this is not so. Serious difficulties are encountered in drying these pellets that do not exist in the drying of taconite concentrate pellets. The ores that present problems are goethite and earthy hematites. Green pellets prepared from these ores have very law shock temperatures, 200-600° F. The shock temperature of a green pellet according to our definition is the highest initial temperature to which a green pellet may be exposed without suffering decrepitation. Decrepitation may involve spalling, fracturing or total disintegration. The poor shock properties of these green pellets result from the inability of the vaporized water to escape freely and easily as it is formed with¬out affecting the integrity of the pellet. As a consequence, the pellets must be carefully dried prior to induration. This careful treatment is costly. The slow drying process restricts productivity and requires larger furnaces than desired. The use of an additive to elevate the shock temperature of the green pellets would increase productivity. Bentonite is used in some pellet plants to improve balling but it raises the shock temperature only slightly. Nalco became interested in the shock temperature problem because of its activity in the development of organic pelletizing aids for taconite concentrates. The findings reported here are an outgrowth of our experimental work on the development of shock temperature additives.

Jan 1, 1967

By William R. Bush

This paper is a presentation of findings based upon an econometric model of the world zinc industry. The model was developed as a simple but useful aid for long-run forecasting and planning purposes. A structure was developed for both simulating real zinc price effects on production and consumption, and for forecasting long-run annual zinc prices and supply/ demand levels. Moreover, a methodology is provided to incorporate the effects of: (1) historic technological advances in zinc supply, and (2) the development of the competitive plastics industry. Finally, reduced form equations are used to generate ex post forecasts to evaluate the model's performance.

Jan 1, 1979

By Andrea Brickey, JUDITH BUABA, RICHARD AMOAKO

This study applies a machine-learning technique known as multiclass logistic regression on a 10-year injury dataset from the U.S. Mine Safety and Health Administration (MSHA) to determine miners’ susceptibility to injury and to help identify significant risk factors associated with different classes of injury. The analysis identifies specific risk factors that influence a mineworker’s susceptibility to a given class of injury: nonfatal with no days lost or restricted activity; nonfatal with days lost and/or days of restricted work activity; and fatal and total permanent or partial permanent disability. These factors include miner’s age, mine type (coal versus noncoal), experience on the current job (years), shift start time, employment type (operator versus contractor), mining district and type of accident. The results of the analysis indicate that a miner’s experience on the job (the number of years worked in a current job) is a significant risk to injury occurrence, even for those with decades of total mining experience.

By Eugie Kabwe

The velocity of detonation (VOD) is a significant property considered when rating an explosive, and it is quantified as a confined or unconfined velocity. The confined velocity is more significant as explosives are usually used under a definite degree of confinement. This study evaluates the stepwise increment of the air-deck volume from 10 to 30 percent, and its effect on the VOD. The VOD estimation in the 172-mm-diameter explosive column was conducted using the Dáutriche technique. The air-deck volume increment has an attenuation effect on the steady-state VOD, and detonation failure is high at 30 percent air-deck volume. This attenuation effect is directly linked to the explosive’s rating and efficacy. The air-decking approach in this study is different from conventional air-decking techniques in that it does not employ the fixed blasthole parameters, air-deck volume and specific VOD. 

By RENE GOMEZ, RAUL CASTRO

Estimation tools and models are now available to estimate fragmentation, but some variables have yet to be studied to understand their effect on the fragmentation process. One such variable whose mechanisms have yet to be studied is the residence time, which in block caving directly depends on the distance that fragments travel from their original position in the broken ore to the drawpoint. In this study, granular material fragmentation was characterized during its flow to understand its characteristics and mechanisms. The results show that the breakage of fragment singularities occurred mainly within medium and smaller sizes, increasing fine material during flow. Thus, the main fragmentation mechanism in experiments was identified as abrasion between rock fragments where fine material continuously increases as distance increases in spite of the high rock strength and the piston flow movement used. The results presented here can be applied to incorporate fragmentation during flow of large travel distance of ore such as in block caving.

By Yuting Xue, Danqing Gao, Brijes Mishra

Heterogeneity and discontinuity significantly affect rockmass strength. Past studies have largely used arbitrary scaling approaches to produce rockmass strength from laboratory rock tests. This paper proposes a stochastic approach to produce rockmass strength from laboratory rock tests. Based on the laboratory data, MATLAB with an extreme value stochastic model generated a database for each physico-mechanical property of the rock. Then finite-difference software FLAC2D simulated laboratory-sized rock specimens. Random material properties in MATLAB were generated using the grids developed in the numerical model. The random properties were then applied to the final FLAC2D model. Model runs simulated the approach performed in the laboratory. The results from the model indicate that a stochastic approach produced compressive strengths that were lower than those from the deterministic approach. Failure modes for each specimen were different from those observed in the laboratory. In addition, random density also influenced the failure mode, highlighting the importance of stochastic analysis in rocks.

By Sergio Godoy P.

The Los Bronces porphyry copper deposit is located in the high Andes of Central Chile. Ore is mined from several tourmaline breccias and from an earlier porphyry. After years of experience in the geostatistical estimation of reserves in different zones of the ore body, we believe that success lies in considering the evaluation as an integrated process beginning with the analyses of the drilling density and sampling methodology, ending with the critically important reconciliation between the estimated and the actually extracted ore, in general, when errors or differences occur, focus is centered in the calculation stages of geostatistics. However, this paper demonstrates that all the evaluation stages are equally important and require the direct and continuous geologic input to ensure the best possible estimate within the frame of the geologic constraints.

Jan 1, 1992

By S. G. Vick, K. E. Robinson, W. D. Webb

INTRODUCTION This paper discusses two uranium tailings waste disposal studies that reflect the United States Nuclear Regulatory Commission (NRC) regulatory actions and their changing requirements during the mid to late 1970's. Present guidelines require that all new uranium tailings impoundments be designed and constructed to eliminate, to the extent that it is reasonably achievable, exposures and risks to the public from the tailings. This includes positive measures for control of seepage losses from the impoundment and for control of radiological releases caused by wind and water erosion. Long-term stability of the reclaimed impoundment is also a very important requirement. That is, it is intended that the tailings impoundment, once it is reclaimed, will require little or no care or maintenance as long as the uranium tailings remain a hazard. Principally because of the long-term stability objective, the NRC has now identified subsurface burial of the tailings as the "prime option" for tailings disposal. The environmental implications of these proposed regulatory actions are obviously desirable. The economic implications the actions may have on a particular project are not always so obvious because they are so dependent on environmental suitability of site conditions. Selection of a site with favorable topographic, geologic and hydrologic conditions will usually result in the most economically and environmentally attractive alternative for tailings disposal. The first project discussed in this paper was initiated before the NRC guidelines had been developed to favour subsurface burial. At the beginning, seepage and radon emission control requirements were moderate. Constraints were imposed on the design by site topography, geology, and project capitalization considerations, factors which were dealt with according to straightforward engineering and design principles. More serious constraints were imposed by changing regulatory requirements. Unlike the more usual engineeringrelated constraints, regulatory requirements were upgraded during the design process, causing the design itself to undergo numerous modifications. The second project was initiated after the NRC proposed regulations had become better defined and below grade burial appeared to be the preferred

Jan 1, 1980

By Alfred Opengart

During any rush hour, tens of thousands of automobiles clog the main highways leading into or out of our large cities. Inevitably one or more cars stall or plow into another, causing a momentous traffic jam. Traffic backs up for miles as drivers try to maneuver around the roadblock. As commuters, we grin and bear the inconvenience, rationalizing the delay as part of the price one pays to live in a modern society. The truth of the matter is that the engineers planning the roads have the know-how to build adequate bypass alternatives into their design. The problem is one of economics -- can the cost of eliminating roadblocks be justified? Engineers designing solutions to complex materials handling problems for modem distribution centers are just now beginning to ask this question in relation to their work. Unfortunately in many instances, it has taken an expensive "traffic jam" to bring this question to the front. In these cases, a seemingly practical system promising an attractive return on investment -- using the latest equipment and computer controls -- was designed and installed. Everything went according to plan until one day a breakdown occurred. .Product flow stopped, and management realized it was at the mercy of the "machine." In such situations, management had assumed it could minimize the risks of the breakdown by injecting extra manpower to operate the system manually and pay the associated costs. What it had not recognized is that manual intervention is nearly impossible with sophisticated systems. Thus, too often -- and sometimes too late -- management found itself footing a very high bill for losses incurred because of major production stoppages and missed customer shipments.

Jan 1, 1973

By Wilbur I. Duvall

INTRODUCTION This chapter outlines some general principles and procedures that a rock mechanics engineer can use to arrive at a logical design for the size, shape, and spacings of underground openings in various types of com¬petent rock formations. Rock formations can be clas¬sified into six major categories which are useful for design purposes, provided the necessary input data are available regarding the geology of the site, the physical properties of the rock, the in-situ stress field in the rock, and the general geometry of the underground openings. The US Bureau of Mines (USBM) developed a rock classification system based upon these concepts and found it to be useful for design purposes (Obert, et al., 1960; Obert and Duvall, 1967). This classification sys¬tem is given in Table 1; however, an extra column has been added to the original classification to indicate the appropriate design techniques for each rock class. In this classification system, two main classes of rock are considered: competent rock and incompetent rock. Competent Rock Competent rock is any rock which, because of its mechanical and geological characteristics, is capable of sustaining underground openings without the aid of any structural support except that provided by unmined rock in the form of pillars and side walls, etc. Roof bolts and small random props which support only local loose rock are not considered structural supports. Competent rock is further subdivided into three ad¬ditional categories-massive, laminated, and jointed¬ which are defined as follows: Massive Rock: Massive rock is a rock formation where the spacing between mechanical defects such as joints, partings, or faults is equal to or greater than the critical dimensions of openings, or where the strength of the bond across these mechanical defects is com¬parable to the rock strength. Laminated Rock: Laminated rock is a rock forma¬tion divided by approximately parallel planes of weak¬ness into lamina whose thicknesses are small compared to critical dimensions of openings and where the bond between the lamina is weak compared to the rock strength. Elastic Rock-This is rock whose physical proper¬ties will permit the use of elastic theory to predict strains and displacements from applied stresses. Inelastic Rock-This is rock whose physical proper¬ties are such that strains and displacements are a strong function of time as well as applied stress. Incompetent Rock Incompetent rock is any rock which, because of its mechanical and geologic characteristics, is not capable of sustaining underground openings without the aid of additional structural support in the form of linings, steel sets, or systems of props. This classification system for rock depends not only on the mechanical and geologic characteristics of the rock but on the size of openings and their depth be¬low the surface. For example, many competent rocks at shallow depths for small stress fields could become inelastic rock at greater depths and larger stress fields, or competent massive rock for small openings could be¬come laminated or jointed rock for larger openings. Thus, to classify rock for design purposes requires a knowledge of the geologic properties of the rock mass, the physical properties of the rock, the general size of the openings to be mined, and the average range of the in-situ stress field to be encountered. To design underground openings and structures in rock, it is necessary to use criteria of failure for rock under various stress conditions, and to use safety factors to allow for differences between laboratory and in-situ strength properties of rock and to account for errors in¬troduced by the various assumptions made in the design process. Criteria of failure based on maximum stresses have been found to give reliable results in practice. Thus, it is assumed that rock will fail in tension when the tensile stress exceeds the tensile strength of the rock as determined by a standard modulus of rupture test on samples of rock core. If the tensile stresses in rock are small, then it is assumed that the rock will fail at a value of compressive stress equal to the compressive strength of the rock as determined by standard uniaxial compres¬sive strength tests on samples of rock core. These fail¬ure criteria, when used with appropriate safety factors, can be expressed as:

Jan 1, 1982