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By J. Andrew McGlenn, Greg Emslie, Murray Gant

The Second Narrows Water Supply Tunnel will ensure system reliability in the event of a major earthquake and increase the Greater Vancouver Water District’s capacity to meet a growing population’s longterm needs. It includes a bored tunnel between two deep shafts located in North Vancouver and Burnaby, BC, Canada. The support of excavation for the 16-meter-diameter (52.5 ft) TBM launch shaft consists of 83-meter-deep (272 ft) unreinforced concrete slurry walls. This paper discusses challenges encountered during construction of the launch shaft slurry walls, namely excavation methods and slurry loss, and mitigative solutions implemented to successfully complete the shaft with minimal impact to project schedule.

Dec 1, 2022

By Karoly (Charles) Kocsis, Jeff Johnson, Felipe Calizaya, Tulio Dias, Natanna Nunes

Two pressure balancing chambers were constructed at a Colorado coal mine to reduce the risk of spontaneous combustion. Each chamber was established by installing a Kennedy stopping at about 10 ft (3 m) in front of an isolation seal, and equipped with two safety doors, a nitrogen injection system, and a set of environmental monitors. Several pressure balancing tests for different ventilation conditions were conducted in these chambers. During each test, pressurized nitrogen was injected into the chamber and the pressure differentials across the stoppings and seals monitored. This study presents a summary of the results achieved, lessons learned, and the basic requirements to operate a pressure chamber effectively.

Feb 1, 2024

By P. J. G. du Toi

Anaconda's experience with percussion longhole drilling in Butte, Montana, has consisted of six phases: 1. Drilling horizontal blast holes in stopes with push feeds. 2. Ring and parallel blast hole drilling in longhole stopes with bar mounted as well as skid jumbo mounted longhole drifters. 3. Ring and parallel drilling in raise climber shrinkage stoping using special raise climber drilling decks designed and built in Butte, Montana. 4. Parallel longhole drilling in horizontal cut and fill stopes with monorail jumbo. 5. Drilling water drain holes between mine levels. 6. Drilling leach holes through caved zones into old stope workings for leaching purposes. 7. Sample hole drilling.

Jan 1, 1970

The American Mining Congress International Coal Show, this year’s largest gathering of coal industry leaders, convened May 5-8 in Chicago. Against a 73 000-m2 backdrop of the coal industry’s most productive equipment,* some 23 000 people heard government and industry executives give guardedly optimistic reports of coal’s near future gains. Although a rocky road lies ahead, operators and suppliers still continue their search to improve efficiency. Among the ideas discussed at the show were better underground communications systems, continuous on-line coal analysis, and recovery of hard-to-float coal.

Jan 7, 1980

By E. V. Kuzmin

The rock properties improvement means the exchange of natural properties: increase of stability, strain and compress tension, reduction of gas-liquid filtering property, increase Jung- module, other mechanical and physical parameters of rocks by injection the hardening materials, such as polymeric pitches, micro-or geocements by special technology under high pressure, to fill cracks. Flow of liquid materials between the rock units and hardening under high pressure create full redistribution of rock pressure in rock massif. There are many reasons to use this technology in underground mining, tunnelling, creation barrier technology in raioactive, chemical and other danger material site etc.

Jan 1, 1996

By James J. Komadina

INTRODUCTION Newmont Gold Company's Rain operations are located in Elko County, Nevada, approximately 9 miles southeast of the Town of Carlin.The property was submitted to Newmont Exploration Limited in 1979 and underwent development drilling over the course of the next four years, culminating in the completion of a project feasibility study in October 1986. Initial project scope included development of an open pit mine, an 815,000 DSTPY heap leach, a 572,000 DSTPY mill (Mill No. 3), and associated support facilities. Approval to proceed was given by Newmont Gold Company management in June 1987. Detailed engineering began in early July, followed immediately thereafter by procurement of major equipment components through various second hand sources. PROJECT DESIGN Keep It Simple In early August, Newmont Mining Corporation, parent company of Newmont Gold Company, became the takeover target of an "investor" group headed by T. Boone Pickens. Details of the ensuing events have been well documented by the press; suffice to say their impact on this project was material and required immediate flowsheet changes. Project design throughputs were increased to 1,000,000 DSTPY and 760,000 DSTPY for the heap leach and mill, respectively, in mid- September. These changes caused major project headaches as all general arrangement drawings had been approved and structural steel as well as concrete contracts were in place. Additionally, ground breaking was to commence in two weeks time! Rain project management assembled shortly after the announced changes, to devise an engineering and construction strategy capable of handling these new business conditions. The project had been justified using a gold price of $325 per ounce with a forecasted overall cash cost per ounce of $230. Hence, strict control of capital expenditures was necessary to maintain development economics. Mill start-up had also been moved forward one month, to August 1, 1988. To meet an already ambitious schedule, construction techniques needed to be simple and proven as most of the facilities were planned for erection during winter at a site with design criteria of -40F and 90 mile per hour winds. Perhaps the most critical factor requiring consideration was that of personnel. Newmont Gold's revised business plan called for corporate-wide production increases from 587,000 ounces per year in 1987, to 1,400,000 ounces by mid- 1989. Labor requirements were forecasted to grow from 900 employees to over 2,100. This fact, in combination with the rapid growth of Nevada's gold industry, led to the expectation that turnover of operating personnel would be extremely high. It was concluded that, to meet cost, time, and operational goals, the necessary strategy could be succinctly put - "Keep It Simple." Mining/Metallurgical Factors The Rain deposit consists of three interconnecting mineable shapes with host rocks ranging from 90%+ barite to a highly silicified jasperoid. Due to a limited number of mining faces in the first two years, in-pit blending

Jan 1, 1990

By T. J. Batchler

"INTRODUCTION A variety of standing supports are being applied in underground coal mining operations to assist in providing stable mine entries. Standing support performance requirements depend on the nature of the ground deformation behavior, and therefore require a good understanding of the interaction between the support and ground to achieve an optimum roof support system. Mining operations often employ standing support strategies that are unique to their mine. A support system that functions successfully in one situation could fail in another situation. It is important that the design and installation of the standing support systems provide the highest probability of preventing roof falls. Considerable research and development has been conducted by support manufacturers to develop standing support technologies for the mining industry. The National Institute for Occupational Safety and Health (NIOSH) researchers, with the cooperation of various support manufacturers, have developed a testing protocol that evaluates performance characteristics of these standing support systems.. Using this protocol, each of these support systems has gone through rigorous safety performance testing under controlled loading conditions in NIOSH’s Mine Roof Simulator (MRS). It is important to understand the unique performance characteristics of each type of standing support. This information allows mine operators to determine if the support system is compatible with the conditions in the mine and to compare each support system and determine if that support will provide equivalent or improved support capability. This paper provides a comprehensive summary of support performance to facilitate this objective. SUPPORT DESIGN CRITERIA AND THE GROUND REACTION CURVE Standing roof support systems are designed to prevent unplanned roof falls. The selection of the standing support is based on the interaction of the support with the surrounding rock mass, and its function is to assist the primary support system in maintaining the integrity of the immediate roof. The standing support works to control the immediate roof structure by resisting deformation that contribute to delamination of the bedded layers and displacements that lead to separation of the bolted zone from stable roof structures above the bolted horizon (Barczak, 2005). Standing supports should be installed early enough and develop sufficient capacity to bring deformation of the ground into equilibrium before a critical deformation is reached that leads to a detached block condition, at which point the standing support will be required to carry the entire dead weight of the detached rock mass to prevent a roof fall from occurring (Mucho, 1999). The ground reaction curve (GRC) can be used to assist in determining the compatibility and design requirements for a support system. It is important to understand the significance of the ground reaction relative to the support design requirements. The ultimate objective is to match the support behavior to the ground response and create equilibrium (stability) of the rock mass. This equilibrium is accomplished when the support loading intersects the ground reaction curve (Figure 1). Essentially, the ground reaction concept implies that the convergence in the mine entry is controlled by the magnitude of the support resistance. However, as a passive support, the standing support develops its loading through convergence. As such, the support needs to maintain its load capacity through the associated deformation of the ground and resulting entry convergence until the equilibrium condition is reached. This requirement causes factors such as the support stiffness, peak capacity, yielding characteristics, and stability to be fundamental to proper support design and application. NIOSH contributes to providing this understanding through full-scale performance testing of support products in the Mine Roof Simulator."

Jan 1, 2017

By V. Svalbonas, S. M. Jones, A. Boughey

In June 1998, the world's largest grinding mill, the 40 ft (12.2 m) diameter 20 MW Cadia gearless SAG mill, was commissioned. This was a leap of over40% above the largest operating SAG mill. A significant saving in capital cost gave the incentive necessary for a single mill line at Cadia, resulting in the selection of the 40 ft (12.2 m) diameter mill. Now, after 18 months of operation, this paper will review the significant items involved in the development, design, manufacture, installation, and operation of this mill.

Jan 1, 2000

By N. Hoffman

Accurate, repeatable density measurements of a coal-magnetite-water slurry are difficult to achieve using a nuclear density gauge. Changes in the coal-to-magnetite solids ratio cause fluctuations in the readings of nuclear gauges. To investigate this problem the Electric Power Research Institute's Coal Cleaning Test Facility compared the performance of a nuclear density gauge on a coal-magnetite-water slurry with the performance of a differential pressure gauge modified with a new pressure sensor. A second aim of these preliminary tests was to determine if the differential pressure gauge is also sensitive to the type of solids in the slurry. This paper explains current slurry density measurement practices, describes the nuclear and differential pressure gauges used in the CCTF tests, and presents test methods and results.

Jan 1, 1986

By S. M. Pickering

Banks frequently manage large privately owned mineral land trust accounts for estate heirs. The bank has a fiduciary obligation to follow the “Prudent Man Rule”, which requires that trust properties be managed at least as well as a prudent and knowledgeable owner could. However, banks may not have internal staff proficient at mineral property values, lease contracts, royalties, mining practices, etc. This is an opportunity for experienced geologic consultants and certified minerals appraisers to provide needed help. Items valuable to Trust managers may include: 1. Marketing privately owned mineral trust lands to mining or oil & gas firms, assuring competitive offering prices and terms; 2. Negotiating favorable new mineral lease and purchase-option contracts; 3. Monitoring progress of mining, royalty payments, land reclamation, and environmental clean-up work; 4. Balancing future mining income with later industrial, commercial or housing development, timber harvest, etc.; 5. Assuring that Depletion Allowance tax advantage is taken for actual mine royalty payments, but not for annual non-mining lease (rental) income; 6. Appraising in-ground mineral value for bank audits, estate tax valuations, and equitable property division between heirs; and 7. Serving as expert witness, representing the legal interests of the bank, trusts, and the mineral heirs in litigation. Banks do welcome reliable advice which assists them in achieving the “Prudent Man Rule” and improving mineral income to their land Trust accounts.

Jan 1, 2002

By Rami Abousleiman, Gabriel Walton, Sankhaneel Sinha

"Although conventional coal mine designs are conservative regarding pillar strength, local failures such as roof-falls and pillar bursts still affect mine safety and operations. Previous studies have identified that discontinuous, layered roof materials have some self-supporting capacity. This research is a preliminary step towards understanding these mechanics in coal-measure rocks. Although others have considered broad conceptual models and simplified analogs for mine roof behavior, this study presents a unique numerical model that more completely represents in-situ roof conditions. The discrete element method (DEM) is utilized to conduct a parametric analysis considering a range of in-situ stress ratios, material properties, and joint networks to determine the parameters controlling the stability of single-entries modeled in two-dimensions. Model results are compared to empirical observations of roof-support effectiveness (ARBS) in the context of the coal mine roof rating (CMRR) system. Results such as immediate roof displacement, overall stability, and statistical relationships between model parameters and outcomes are presented herein. Potential practical applications of this line of research include: (1) roof-support optimization for a range of coal-measure rocks, (2) establishment of a relationship between roof stability and pillar stress, and (3) determination of which parameters are most critical to roof stability and therefore require concentrated evaluation.INTRODUCTIONRecent studies on pillar design have suggested that the assumptions utilized in traditional methods such as tributary area theory (TAT) (i.e. overburden has no self-supporting capacity, infinite pillar array, and CHILE material properties) are invalid in many geo-mining conditions (Esterhuizen, Mark, and Murphy, 2010; Frith and Reed, 2017). Although TAT is conservative with respect to pillar loading, and mine fatalities have steadily decreased since 1990, roof-falls and pillar bursts still occur and injure hundreds of miners per year (Mark, Pappas, and Barczak, 2011). Even though large-scale global mine failure has not occurred in a US coal mine since 2007, the mechanics of global and local stability as governed by the relationship between geologic parameters, mine geometry, and engineering design are still not well-constrained.Numerical methods are a highly effective tool that can be used to gain further insight into these relationships. When using such an approach, calibration to existing empirical relationships is imperative to ensure that numerical model results are realistic. In this study, we utilize the discrete element method (DEM) approach in Itasca’s Universal Distinct Element Code (UDEC v. 6.0) (Itasca, 2010).DEM accounts for explicit separation and contact of individual deformable blocks (Jing, 2003) and captures how discontinuities can affect system behavior. Discontinuous and anisotropic rockmass properties are typical features in coal-measure rock which contain various horizontal (bedding) and sub-vertical (joints) fractures depending on their depositional environment, diagenesis, and historic and current stress states."

Jan 1, 2019

In September 2003, a test was conducted to see if a115-mm- (4.5-in.-) diam Mocap Vari-Stem blasthole plug could improve the pattern of explosives using different top stemming material. The test took place at the J.S. Faulkroad and Sonsstone quarry in McCalisterville, PA. The test consisted of a production stone blast. Half of the holes were stemmed with standard crushed stone. Two-thirds of the remaining half were stemmed with Vari-Stem plugs and crushed stone. And the remaining one-third of the second 50 percent was stemmed with Vari-Stem plugs and only drill cuttings.

Jan 1, 2004

By David E. Nicholas

Design of underground openings is becoming more critical as the mine deposits become lower in grade, initial investments increase, ore depth increases, additional safety regulations come into law, and increased ore recovery is required for conservation of minerals. Stability of these openings is dependent on the strength of the rock mass and the pre-mine stress field. The rock mass is composed of solid blocks of rock (rock sub- stance) and structural features (faults, joints, bedding, etc.). Methods of testing the rock mass strength are improving and be- coming more common, however it is difficult to justify the high cost of large scale testing for an initial mine design. An alternative to testing the rock mass is to measure the rock substance and the structural features separately, and then combine them to estimate the rock mass strength. The rock mass strength will vary depending on the orientation of the opening with respect to the structural features. The other factor affecting the stability of underground open- ings is the pre-mine stress field. Methods are available to measure "directly" the pre-mine stress in competent and relatively massive rock. These methods are costly to employ, therefore, they may not be justified in an initial study. The pre-mine stress field can be estimated based on the structural relationships formed from past tectonic events.

Jan 1, 1976

By Y. Luo

In designing and operating underground room-and-pillar coal mines, it is always difficult to achieve a good balance between preventing surface subsidence and achieving high recovery ratio. In this paper, a design methodology applying the pressure arch theory is proposed, and the principles and mathematical models involved are detailed. A computer program was developed to carry out the design optimization process and was applied to the examination of a documented case in which a massive cascading pillar failure had occurred over a large area in a shallow coal mine. The results indicate that the proposed design method can be applied to prevent subsidence while achieving reasonably high recovery ratio for roomand- pillar mining operations.

Jan 1, 2014

Silver bearing bulk sulfide concentrates from several Peruvian mines were autoclaved in a 19 liter (five gallon) laboratory autoclave in Lima, Peru. Cyanidation of autoclaved concentrates following a hot lime jarosite destruction step extracted over 98 percent of the silver and over 95 percent of the gold. Autoclave operating parameters such as time, temperature, pulp density and autoclaved solids recycle were investigated and reaction rates determined. The problems of excessive heat generation, silver solubility during autoclaving, and formation of pellets containing unreacted sulfides were addressed. The data presented will be used to design a continuous autoclave pilot plant to pro-vide reliable scale up data for a 50 -100 ton per day facility.

Jan 1, 1992

By David W. Wisecarver

Kennecott Copper Corporation and the U. S. Bureau of Mines cooperated in a full-scale slope stability research project at the Kimbley Pit near Ely, Nevada. The west wall of the Kimbley Pit was mined from an over-all slope angle of 45° to an over-all slope angle of 57° and the pit was deepened nearly 50 feet. Mining was begun February 10, 1966, and completed October 30, 1966. Approximately 2.55 million tons of ore and waste were mined. The project was designed and carried out to learn more about the behavior of a pit wall as its slope angle is steepened and to obtain a possible insight into engineering parameters for use in design of future slopes. Data from this project are presented as obtained from (1) instruments installed in two adits for deformation and displacement measurements, (2) a subsidence network installed on the surface above the steepened wall, (3) pre- and post-mining observations of stress in rock, (4) sonic-velocity measurements, and (5) seismic and microseismic investigations. Changes occurred in measured quantities as the slope was steepened but stopped when mining was completed. Agreement was noted between the measured changes and predicted changes obtained from calculations using the finite element technique. Subsidence surveys and microseismic studies show the steepened pit wall to be stable.

Jan 1, 1968

By John H. Paugh

Hydraulic slurrying and pumpability characteristics of phosphate matrix (ore) have not been quantitatively defined. An elemental triangular diagram analysis of rock/sediment texture is used to classify the nature of the ore; then related to empirical field data of hydraulic pressureand production yardage ratios. This experiment is applied as a geotechnical tool to provide empirical data of ore slurry and pumpability characteristics as key considerations in the design of slurry pipeline systems. A real texture variability maps are developed on a section of land to assist mine engineering planning.

Jan 1, 1981

By Shanming He, Jinliang Wang, Xiaoming Wang, Chunfa Liao

Large amounts of manganese-rich slag were generated from smelting low-grade manganese ore containing high iron and high phosphorus in electric furnace or blast furnace, which contain 25–40 mass% Mn. This paper describes an efficient hydrometallurgical process for the utilization of high manganese slag instead of conventional usage of pyrometallurgical route for manganese recovery. Pressure acid leaching of manganese-rich slag using air as pressurized gas is studied systematically. The effects of mass ratio of manganese-rich slag to pyrite, concentration of sulfuric acid, leaching temperature, partial air pressure, leaching time, and liquid-solid (L/S) ratio on the separation of manganese with other main impurity components were investigated comprehensively. Under the following optimal process conditions, weight of manganese-rich slag powder,100 g; mass ratio of manganese-rich slag to pyrite, 20:1; sulfuric acid concentration of 140 g/L; air pressure of 0.6 MPa; leaching temperature of 140 °C; leaching time of 1 h; L/S of 7:1; ore size of 75–80 μm; and stirring rate of 600 rpm, the extraction rate of Mn reached 94%, and the dissolution percentage of Si, Al, and Fe are as low as 2%, 6%, and 10%, respectively. The leaching slurry presented a good solid-liquid separation characteristic. The silicic acid formed during sulfuric acid leaching manganese silicates was converted to filterable dehydrated SiO2 particles which precipitated in the residue under the condition of higher temperature with higher pressure. The effect of adding pyrite may be to reduced iron ions and decreased the output of iron hydroxide colloid and also reduced MnO2 to manganese sulfate in sulfuric acid leaching. Thus the formation possibility of colloid such as silica gel and iron hydroxide was decreased, and higher yield of manganese sulfate could be achieved.

By E. P. Evert

Profitable marketing of most minerals is dependent upon the total delivered cost to the user. Transportation costs are often greater than the value of the mineral f.o.b. the mine or processing facility. In some cases, transportation costs are three to five times the mineral cost. For many years, transportation costs were controlled by a complex system involving the transportation companies and supervised by regulatory agencies. This paper will deal with the effects of deregulation on rail costs and outline the major changes in transportation economics.

Jan 1, 1985

By W. Jacobi, K. Eisfeld

The primary objective of dosimetric modelling for the inhalation of radon daughters is the evaluation of the dose distribution and of the mean dose to sensitive cells or target tissues in the respiratory tract which are assumed to be responsible for the initiation of lung cancer. The results of such dosimetric models are influencing the practice of radiation protection in a twofold manner: Firstly, they enable us to identify appropriate operational quantities for air monitoring and for the surveillance of individual exposures to radon daughters. Secondly, they can be used to derive secondary and operational limits for these radionuclides from the basic dose limits. The dose to target tissues in the lung from inhaled radon daughters depends on various physical and biological parameters: The unattached fraction of daughter atoms, the AMAD of the carrier aerosol for attached atoms, the geometry of the respiratory airways, the breathing conditions, the parameters for the retention and translocation of daughter atoms in the different lung regions, and the location of the target cells or target tissues, respectively. Therefore, dosimetric modelling for radon daughters has to include a sensitivity analysis showing the influence of these parameters. To meet these objectives we have recently described in a comprehensive report an improved dosimetric model for the inhalation of 222Rn, 22ORn and their short lived daughters (Jacobi and Eisfeld, 1980). In the following this model is shortly described and the main results are summarized. DOSIMETRIC MODEL [Model Structure]. For the geometry of the bronchial airways the model A of Weibel (1963) was used. Each bronchial generation i (i =0.1 .... 16) was considered as a separate compartment i, for which the following transfer pathways for radon daughter atoms were taken into account (see fig. 1): (1) the uptake by deposition (deposition probability wi); (2) the translocation by ciliary clearance (rate constant [A]i); (3) the transfer to blood by diffusion through the bronchial epithelium (rate constant [A]b). To distinguish between attached (Index a) and free (index f) daughter atoms each bronchial generation was divided in two subcompartments (i.a and if) with a transfer rate constant [a]s (ia- if) characterizing the desorption or dissolution rate of attached atoms in the mucus fluid. Thus for daughter atoms primarily deposited in attached form the transfer to blood is a twostep process with the rate constants [a]s and [A]b which were assumed to be independent of the generation number i. [Deposition]. The deposition probabilities wi in each bronchial generation were calculated on the basis of the laminar diffusion model of Gormley et al. (1949); however the deposition in the upper airways was corrected for turbulent air flow, taking into account the results of our deposition experiments (Martin et al., 1972). Figure 2 shows the resulting deposition probabilities per unit surface area of the bronchial generations for nose breathing at a rate of 20 1/min. The values for attached daughter atoms refer to an AMAD of 0.2 - 0.3 µm ([O]g =3) for the carrier aerosol; the deposition values for free atoms were derived with a diffusion coefficient of 0.05 cm2/s, assuming a prefiltration of 50% in the naseopharyngeal region.

Jan 1, 1981