Search Documents

By J. G. Groppo, T. L. Robl, C. J. McCormick, W. M. Lewis

The combination of froth flotation and hydraulic classification can facilitate the production of a high-quality pozzolan that meets or exceeds ASTM specifications. This combination has been rigorously evaluated and results of pilot-scale testing are presented. Pilot-scale testing was conducted on fly ash from two active electric utility storage ponds. The tests demonstrated that a high-quality and consistent pozzolan could be produced using Advanced Pozzolan Technologies' Fast Float™ Process. Along with the pozzolan, the additional production of aggregate for masonry mortar and the production of a low sulfur, medium-Btu fuel were also demonstrated. The Fast Float™ Process incorporates several simple unit processes to ensure pozzolan consistency. Classification controls the particle size distribution, which is critical for achieving early strength;flotation controls the grade with respect to L.O.I.; and dewatering controls the moisture content.

Jan 1, 2000

By Neil H. Bostick

This research, sponsored at Stanford Research Institute by the Grand Junction Operations Office of the U.S, Atomic Energy Commission, was an outgrowth of the concern that presently-known ore reserves may be inadequate to meet the projected demands of nuclear power reactors. The original program at SRI was to design a comprehensive geological information system and use it to store and analyze the very great quantity of data needed to estimate uranium ore reserves. Study of the problem showed that it could be solved only by use of modern electronic data processing techniques, so such a comprehensive system was designed and tested. The system test was satisfactory, but input lead time and total expense were shown to be too great for the system to be practicable for the AEC under present circumstances. Thus, based on results of the earlier research, a specialized and simplified procedure for predicting approximate uranium ore reserves was devised. The prediction is based on general geology of specific area cells of the earth, in order to provide complete volume coverage; the strata in these ores are evaluated for uranium ore favorability on the basis of a few selected criteria in order to allow rapid data input. Since the bulk of U.S. reserves are in clastic host rocks only such strata are considered in this work. This paper describes the structure and some details of the resource system and how it was tested in rn area of the western United States.

Jan 1, 1969

By W. A. Wilkinson

Mining companies today are under increasing pressure to boost output from their existing mines and to bring new projects online quickly. Fundamental to the long-term performance of an operation is geologic modeling and mine planning. To maximize mine profitability, planners and schedulers must account for a staggering array of variables and create accurate mining plans that meet production and profit targets. Not surprisingly, this can be a difficult task, and getting it wrong can result in large unforeseen costs and significant lost revenue opportunities. This paper discusses the top five challenges geologists and engineers are facing in developing mining plans.

Jan 1, 2012

By V. T. McLemore

NMBGMR has been collecting data on uranium mining districts, mines and mills since it was created in 1927 and has converted years of historical data into a relational database that can be imported in ArcMap. The database includes information on mining districts, mines, mills, geochemistry, photographs, and bibliography. The available data includes location, production, reserves, geologic, geochemical, resource potential, and other data. The NURE stream-sediment data provides geochemical analyses for >27,000 samples collected in New Mexico during 1970s. The NURE hydrogeochemical data provides analyses for water samples. ArcMap includes location of individual ore bodies as polygons and incorporates the mines and NURE data as individual site locations. The purposes of these databases are to provide computerized data that will aid in identifying and evaluating resource potential, resource development and management, production, and possible environmental concerns, such as physical hazards (i.e. hazardous mine openings), indoor radon, regional exposure to radiation from the mines, background geochemical data and point-sources of possible pollution in areas of known mineral deposits.

Jan 1, 2010

By Yuchen Wu, Jing Mei, GUOZHONG LIU, KE GAO, Songjie Tian, Jianwei Cheng, Yu Wang, Yuhang Wu, Hui Wang

The stability and integrity of protective coal pillars between the longwall working face and development roadways are greatly affected by the mining activities such as the development face advancing or retreat mining. Due to underground strata pressure, the coal pillar cracks could be further developed and then the air leakage passages (mainly cracks) could be produced greatly. The air circulation caused by the atmospheric pressure difference between the two sides of the coal pillar may also provide suitable conditions for the possible spontaneous combustion of the residual coal in the mine gob. In this paper, a typical the protective coal pillar in a Chinese coal mine is studied. The deformation and stress of coal pillars during the mining process of longwall working face are simulated by using FLAC3D. The displacement and strain of coal pillars are analyzed. Two indexes, the linear fracture rate (LFR) and area fracture rate (AFR), are introduced to characterize the development of internal cracks’ development within coal pillars. By using field measurement, the air leakage intensity distribution due to coal pillar cracks is obtained; the equation of air leakage resistance of coal pillar under the influence of mining is derived. Then, the possible location of large air leakage of coal pillar is determined, which can be used as guidelines to study the possibilities of coal spontaneous combustions happening in pillar or mine gob. The research results help to control such potential hazards in advance.

Jun 16, 2022

By J. C. Nigro

The potential use of prereduced pellets in the burden of the blast furnace continues to be a topic of interest. Several excellent papers have been written describing the theoretical and experimental rewards. (1) (2) (3) (4) (5) (6) (7) (8) (9) Significant increases in iron output and substantial savings in coke consumption are major advantages over conventional iron oxide pellets. The savings are especially important in areas where good coking coal is at a premium. Lower handling and transportation costs may also be factors favoring prereduction. When considering the overall cost of making and smelting prereduced materials the optimum metallization level becomes significant. An analysis by Agarwal and Pratt of the thermodynamic aspects of blast furnace operation with all prereduced pellets shows that the criteria controlling coke consumption depends upon the degree of reduction and upon the percentage of oxygen (present as FeO) removed by solution loss.(8) The authors state that although the chances of obtaining large fuel savings are greatly improved when metallization is high, reduction to the highest degree, which is costly, may not result in the lowest energy requirement per ton of hot metal; thus, over reduction could possibly result in wasted energy in the blast furnace.

Jan 1, 1968

Good morning ladies and gentlemen of the AIME. I was doubly pleased when Toby Yu asked me to present to you my thoughts on the past, the present, and the future of bulk transportation by barge. My first pleasure comes from sharing with you the subject that has been my career for many years. I love this industry in the same way Mark Twain loved our rivers. Somehow, I can find in all of the activities that make up this crazy barge business the same sort of excitement that he found in "steam boating." The second reason for my enthusiasm is that Toby carefully pointed out that the presentation had to be kept to a maximum of 15 minutes. I can promise you that I will hold to his maximum time limit.

Jan 1, 1982

By A. E. Michon

I am Alfred E. Michon, Vice President- International for Burlington Northern Inc. I work for BN's holding company and my responsibilities include co-ordinating the activities of our eight subsidiary companies as they relate to international commerce--an increasingly important aspect of the overall business of our company. Until last April, I was President of the Fort Worth and Denver and Colorado and Southern railroads, subsidiaries of BN. Prior to that, I headed the marketing and pricing area of BN's coal transportation business. Based on my experience in the energy industry, both domestic and international, I would like to discuss the world-wide trend towards the reliance on low-sulfur coal in lieu of natural gas and oil for the generation of electricity. Since pontification on the energy scene world- wide is best left to consultants with scenario-spitting computers, let me in- stead emphasize this trend through two examples. First I will describe the regulatory and economic factors which have encouraged the replacement of natural gas by low sulfur coal as a boiler fuel in the US. BN's investments in track and equipment were instrumental in this conversion. Secondly, I will show how this same combination of factors has created a large demand for steam coal in the Far East. Again, our company's strategy is to facilitate conversion to coal overseas through timely and sufficient investments.

Jan 1, 1982

By I. Pordea

The materials used for the construction of buildings contain natural radionuclides of the U238 and Th232 series and are ? 50% due to land radioactivity. Another component of natural radioactivity is K40, with ? 40%. The presence of these radiopollutants in the final products (i.e. bricks, concrete) due to body irradiation is by two pathways: external irradiation and internal irradiation. External irradiation is due to gamma radiations emitted by Pb214 (RaB) + Bi214 (RaC) from the U238 series, by Ra228 (Mezothoriu I) + Ac228 (Mezothoriu II) + Tl208 (ThC??) from the Th232 series and by the K40 radionuclide. Internal irradiation is due to inhalation of radon (Rn222) and Rn220 (Tn) plus short life descendents (Po, Pb, Bi), radionuclides which are present in concrete. A fraction from radon present in concrete enters into a house leading to internal irradiation by inhalation. In Romania, the maximum concentration of radon allowed for new buildings is 200 Bq/m3.

Jan 1, 2008

By Cary Hirner, Tony Cicchetti, Daniel G. Cressman, Jeff F. Wallace, Prapan Dave, Malcolm Sheehan

The City of Toronto is currently undertaking the design of the Black Creek Sanitary Trunk Sewer Relief Project. The Project involves the design and construction of approximately 20 kilometers of tunnel through shale rock of the Georgian Bay Formation and soft ground soil consisting of glacial till, glaciolacustrine and glaciofluvial sand, silt and clay deposits. The 20 kilometer alignment has been split into four sections of tunnel (1) the 12.9 km, 3.0 meter diameter Keele Trunk Relief Sewer, (2) the 2.9 km, 1.5 meter diameter Keele Trunk Relief Sewer Microtunnel, (3) the 3.9 km, 1.8 meter diameter Jane Relief Sewer, and (4) the 0.5 km,1.5 meter diameter Combined Sewer Overflow Storage Tunnel. Additionally, one 40,000 m3 wet weather flow (WWF) storage tank and numerous WWF connection shafts are to be constructed and connected to the Keele Trunk Relief Sewer to pick up WWF from existing outfalls currently discharging to Black Creek. The anticipated cost of the project is approximately $600 million with construction of the Project’s Phase One Works, the Keele Trunk Relief Sewer and Jane Relief Sewer, scheduled to commence in 2025. This paper provides an overview of the project in terms of the anticipated geotechnical conditions, the scheme developed for design and construction of the tunnel system and the associated schedule and procurement strategy. The consideration for planning of the tunnel system, the risk-based analysis and decision-making process are presented and form the basis for selection of a precast tunnel lining support method in the rock and soft ground.

Jun 13, 2023

By John C. Gould

GENERAL DESCRIPTION The Climax mine is located 161 km (100 miles) southwest of Denver on Fremont Pass astride the Con¬tinental Divide. Climax employs 2800 people to pro¬duce 42 670 t/d (47,000 stpd) of molybdenum ore. The Storke level, the main underground level, produces 19 970 t/d (22,000 stpd); the 600 level, the lowest ac¬tive underground area, produces 7260 t/d (8000 stpd); and the open pit presently produces 15 430 t/d (17,000 stpd), Fig. 1. A panel caving method is possible because of the favorable geology and geometry of the Climax ore body. Geology The Climax deposit is composed of three separate ore bodies formed in a massive Tertiary stockwork which penetrates Precambrian granites and schists. The ore bodies are elliptical in plan with overall dimensions of 914 x 1219 m (3000 x 4000 ft). In section the ore bodies are arcuate with an overall height of 457 m (1500 ft), although the depth is not firmly ascertained. Ore grade decreases rapidly into a highly siliceous cen¬tral core and more gradually toward the outer bounda¬ries of the deposit. The mineralization is relatively continuous in the ore zone and contains few dilution-causing waste inclusions. Molybdenite is contained in pre-ore fractures which were largely recemented during the three mineralization pulses. Postore fractures, with a spacing of a few inches to several meters (feet), render the deposit amenable to caving when it is undercut. The peripheral rock caves similarly to the ore, but the central core is competent and is difficult to cave. Caving Feasibility Successful caving action requires an undercut area of approximately 122 by 122 m (400 by 400 ft). When the undercut area exceeds this minimum distance, the arching effect is lost, and the ore column collapses. Ore extensions from the main cave area less than 122 m (400 ft) wide usually cannot be caved. Waste or low¬grade areas within the deposit can be left if they are large enough to carry weight around openings passing through them. Experience indicates that these areas should be over 30 m (100 ft) in length and width. Smaller unprofitable units of waste, such as postore dikes, are mined to avoid weight problems and result in ore dilution. Successful caving and ore recovery are dependent upon timely ore removal from the undercut zone because columns of immobile ore inhibit caving and concentrate weight onto the underlying workings. Climax experience indicates that a finger (drawpoint) spacing* averaging 10.4 m (34 ft) yields an excellent caving action and a 92.5% ore recovery at the estimated grade. An additional 15% of the ore is recovered-at a diluted grade (Fig. 2). Mine Layout The slusher drift is the primary production facility (Fig. 3). The ore is undercut and caved into the fingers,

Jan 1, 1982

By W. R. Dengler

INTRODUCTION Shaft sinking represents a relatively small proportion of the activities involved in mine development. Because of this limited utilization, shaft sinking has been one of the most difficult functions to mechanize. Although shaft machines (muckers) were introduced more than 30 years ago, the first machines were low-capacity units, and machines of this type did not gain wide acceptance by the mining industry until the late 1950s. However, the increasing depth of underground mines and the es¬calating costs of labor have increased the benefits obtain¬able from high-speed shaft sinking. The result has been a growing need for high-capacity shaft machines. Most of the machines available at the present time have been developed by modifying existing equipment to increase the payload capacity and performance. AVAILABLE SHAFT MACHINES In general, shaft machines may be classified accord¬ing to the types of digging mechanisms and the mecha¬nisms of operation. The available digging mechanisms include clamshells, cactus grabs, front-end buckets, and backhoes. The mechanisms of operation can be classified as either pneumatic or hydraulic. Selection Criteria For efficient operation, the primary consideration in selecting a shaft machine is its capacity. The minimum capacity of the machine should match the capacity of the hoisting system at the ultimate depth of the shaft. In many cases, two machines may be needed to obtain a sufficient mucking capacity. The shaft dimensions and configuration often dictate the type of machine that may be utilized; for example, an overshot loader does not work well in a circular shaft that has a diameter of less than 5.5 m (18 ft). Similarly, a single Cryderman mucker is not suitable for a large-diameter shaft, nor is it applicable where very high sinking buckets are to be used. Other factors for consideration include the degree of material fragmentation, the abrasiveness of the rock, and the amount of ground water that is inter¬sected. Machine Descriptions Riddell Mucker: The Riddell mucker, illustrated in Fig. 1, was first introduced in 1948. This is one of the most common shaft machines in the medium-capacity range. The Riddell mucker consists of a hoisting and traveling mechanism that operates a clamshell suspended on cables. The early machines operated with a 0.3 m3 (10 cu ft) clamshell and had an hourly capacity of approximately 27 t (30 st). This type of shaft machine has gained wide acceptance throughout North America. Essentially, the Riddell mucker consists of standard components, such as the pneumatic tugger hoists that operate the clamshell. The carriage is suspended on rails that also serve as the blasting set, located immediately below the shaft timbers. To effectively position the clam¬shell in the shaft, the operator controls the carriage travel by means of wheels that are driven by a pneu¬matic motor. The Riddell mucker most commonly is used in rec¬tangular timbered shafts. However, some units have been installed with circular rails, allowing them to work in circular concrete-lined shafts. A popular practice with many Riddell muckers is to increase the capacity through the use of larger clamshells, often ranging up to 0.76 m3 (1.0 cu yd), in conjunction with more powerful tugger hoists. In some large rectangular shafts, two Riddell units have been used side by side to achieve a sufficient capacity. Cryderman Mucker: The Cryderman mucker, illus¬trated in Fig. 2, is another common shaft machine in the low- to medium-capacity range. Developed in the early 1950s, it also has gained wide acceptance throughout North America. Equipped with a 0.3 m3 (10 cu ft) bucket, the Cryderman mucker has an hourly capacity of approximately 23 t (25 st). The Cryderman mucker is operated entirely by means of pneumatic cylinders and a pneumatic telescopic boom. The boom is suspended from a sectional frame¬work that is usually located at one end of the shaft. The framework or headframe can be suspended from an independent hoisting system located either on the sur¬face or in the shaft. In large shafts of either rectangular

Jan 1, 1982

By P. W. Hunter

The construction of a major sewerage scheme requiring 15.3 km of 5.5m excavated diameter tunnel in basalt, mixed and soft ground has been undertaken by the Melbourne and Metropolitan Board of Works. A double shielded Tunnel Boring Machine was selected to excavate 13.7 km of basalt and mixed ground. Advanced methods for recording operational data on the TBM were introduced. Progress to date has shown that the TBM can excavate rock very effectively with a best weekly production of 178.8m; soft ground has been encountered and successfully handled.

Jan 1, 1987

By J. V. Thompson

The Powderhorn complex as a source of perovskite (calcium titanate) containing about 1.5% rare earths has been examined in several recent feasibility studies. Much promising exploration and process research has been done in recent years. This paper is presented with cautious optimism and with the acknowledgment that there may be some technical and economic areas yet to be explored. The Powderhorn carbonatite and alkalic stock in Gunnison County, Colorado, lies about 203 airlines km southwest of Denver at an elevation of 2450 to 2750 m (see Figures land 2). All of the mineable ore bodies are owned by Buttes Resources Company of Houston, Texas.

Jan 1, 1990

An information system (I/S) plan is a means for establishing and communicating the direction the organization intends to take to provide the information required for achievement of organizational goals and objectives. The rapid advancements in information technology, the increasing complexity of systems, and the growing dependence of mining companies on these information systems have emphasized the need for more comprehensive I/S planning. This subsection explores this need, the role I/S planning can play within a mining company, and finally describes a methodology for development of an I/S plan.

Jan 1, 1979

By Aimee A. Woolsey

Enterprise Unmanned Traffic Management is a holistic system concept evolving from technological developments in radio frequency where dynamic tracking can be added into current and emerging platforms. This is done through inexpensive RF sensors capable of real-time and cooperative, non-GPS tracking enabling digital visualization of assets, including unmanned aerial systems (UAS). The RF sensors are low size, weight, and power (SWaP), creating efficiencies in energy and material consumption while transmitting positions in real-time and at long ranges. Multiple UAS and other unmanned vehicles can be visualized for risk mitigation in operations,

Oct 17, 2022

By John Songstead

INTRODUCTION The Bunker Hill mine, located at Kellogg, ID, in the Coeur d'Alene mining district, has been a major pro¬ducer of lead-zinc-silver ore since 1887. Since its dis¬covery, it has produced over 25 401 171 t (28 million st) of ore from 20 to 25 veins and ore zones. The mine now covers an area of approximately 1.609 km (1 mile) in length and 0.8 km (1/2 mile) in width and extends from 1097 m (3600 ft) above sea level to 488 m (1600 ft) below sea level. Production is presently at a rate of 1542 t/d (1700 stpd). During 1965, a new stoping method, the Bunker Hill pillar system, was developed to enable the profitable mining of large, low-grade zinc ore bodies. The system was specifically designed to in¬corporate the Atlas Copco T26GH rubber-tired loaders. High productivities were achieved, and the method was adapted for mining the higher grade stopes where large timber square sets are utilized. This results in nearly 100% extraction. GEOLOGY The area encompassing the Bunker Hill mine lies immediately south of the Osburn fault, a major east-west striking, deep-seated strike slip fault which is the dominant structural feature in the Coeur d'Alene district. The Bunker Hill forms a series of veins and mineralized zones which occur as link structures, tension fractures, and breccia zones in folded, interbedded argillaceous quartzites of the Revett and St. Regis formations of the Precambrian belt series. The Rosco ore body is predominantly a zinc ore body above the Cate fault, which is presently known to occur from the 13 level. [elevation 488 m (1600 ft)] to the 1600 level [elevation 304 m (1000 ft) ]. These ore bodies are stringer zones with at least one dominant 1.8 to 4.5 m (6 to 15 ft) wide band of ore. They dip 0.09 to 0.26 rad (5° to 15°) steeper than the local 0.61 rad (35°) dip of the Cate fault, and also deviate 0.26 to 0.52 rad (15° to 30°) in strike from the Cate. Because of the flat dip and fractured weak hanging wall, normal cut-and-fill mining has not proven practical in this ore body. The mechanized timber methods described in the next section and the Bunker Hill pillar system are the mining methods successfully used. MINING METHODS While pillar stoping and mechanized cut-and-fill stop¬ing methods were obviously superior to the widely used timber stoping methods, as far as cost and productivity

Jan 1, 1982

By K. V. Raj, M. McNinch, A. L. Miller, J. Wilson, D. A. Parks

Diesel particulate matter (DPM) has been shown to contribute to various adverse health effects on underground miners. In order to reduce worker exposures, it is critical to measure the levels of DPM in the active work settings and in real time. However, the 5040 method, developed by the National Institute for Occupational Safety and Health (NIOSH), which quantifies the mass of elemental carbon (EC) and organic carbon (OC) in the samples, is based on full-shift samples, and can take days or even weeks for results. Use of real-time monitors could significantly reduce the risk of DPM exposure to miners, and available monitors have been shown to quantify DPM, mainly using the EC and other surrogates. The NIOSH Spokane Mining Research Division is conducting research aimed at developing a field-portable DPM monitor that is able to quantify both EC and OC. One part of this work is to understand the effect of OC on currently available real-time DPM monitors. This paper will present the results from experiments that were designed to observe the effect of OC on real time monitors and compare the results with the NIOSH 5040 method. BACKGROUND Diesel engines remain ubiquitous in mining environments and, as such, are one of the primary sources of ultrafine- and nano-aerosols in the mining environment in the form of diesel particulate matter (DPM). As a result of their small size, DPM has longer residence times in a mine atmosphere than the typically larger mechanically generated dust [1]. In addition, the small size enables DPM to penetrate deeply into the respiratory system [1], and exposure to DPM has been shown to contribute to various adverse health outcomes of the pulmonary system [2] and cardiovascular system [3]. Diesel exhaust has been classified as a carcinogen to humans (Group 1) by the International Agency for Research on Cancer [4]. Due to mounting concern about adverse health outcomes, extensive efforts are being made to reduce workers’ exposure to DPM, with the high exposures that often occur in underground mines being of particular concern [5]. New technologies are being developed to reduce engine emissions and thereby airborne DPM levels, including advanced engine technologies, a host of aftertreatment systems [6], and a variety of alternative fuels. The latter have been shown to markedly decrease respirable DPM and other hazardous components of diesel emissions from mining vehicles [7], yet high exposures persist, especially in underground mines [8]. In order to reduce worker exposures, it is critical to measure the levels of DPM in active work settings. In mine settings, exposures to DPM are measured by collecting air samples on filters (usually full-shift samples) and sending them to a lab for analysis using the Mine Safety and Health Administration (MSHA) P13 method, a variant of the National Institute for Occupational Safety and Health (NIOSH) 5040 method. The 5040 method is designed to quantify the mass of elemental carbon (EC) and organic carbon (OC) on the samples [9], which is then used to determine the concentration in the sampled air. MSHA has set a limit for exposure, which is based on the concentration of total carbon (TC), or the sum of both EC and OC. The allowable TC in the air (time-weighted average over the shift) is 160 μg/m3 of TC [10].

Jan 1, 2019

By John Chapman, Daryl Hockley, Michael Paul, Silvia Jahn

As part of the waste characterisation program to address site reclamation, WISMUT GmbH initiated 56 columns operated as large-scale humidity cell tests. The columns were initiated to assess the acid generation characteristics of waste rock from 14 waste rock piles distributed around the site. Of the 56 tests, 11 are ongoing and have been operational in excess of 160 weeks. The results to date from these long-term tests are surnrnarised. In particular, the methods for, and importance of, establishing the availability of the carbonate neutralisation potential and acid generation potential respectively, are discussed. Geochemical controls on uranium, and the conformity between the geochemical models MINTEQA2 and EQ3/6 in assessing these controls are discussed. Testing indicates that waste rock with an MS-NP:AP ratio in excess of about 2.7 should result in net neutral pH conditions.

Jan 1, 2000

By Christopher J. Vise

Although production operations at mines, representing the extraction and removal of the mined material, often appear to receive the greatest amount of attention, the emphasis given to auxiliary operations is continually increasing. This is due to the changing economic, social, and environmental climate in which modern mines must operate. Auxiliary operations can best be described as those activities that are not directly related to the extraction and removal of the mined material, but must receive proper attention if recovery is to take place in a safe, efficient, and socially responsible manner. In fact, certain mining auxiliary operations, such as strata control and ventilation, are considered to be of such importance that they warrant separate sections in this Handbook. Judging from a mine-personnel standpoint, it is not uncommon for a mine to hire the same number or more individuals responsible for auxiliary operations as the number assigned to production.

Jan 1, 2008