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By William A. Hustrulid

A technical and economic evaluation of the potential for improving mining productivity through the use of underreamers in blastholes, specifically in relation to Minnesota taconite, Arizona surface copper and in situ mining operations is presented. Included are (1) a review of the drilling and blasting practices presently being used, (2) a discussion of current underreamer technology. (3) the presentation of a general economic cost model for underreaming, (4) the application of the model to surface taconite, surface copper and in situ mining, and (5) a summary discussion including required performance specifications, potential overall benefits, and recommendations for further development.

Jan 1, 1977

By Tony S. Calayag

Throughout the mining industry today, new bearing materials - ZA* high-performance zinc-aluminum alloys - are reducing costs of maintaining and rebuilding a wide range of equipment. As replacements for bronze bearings, installed in original equipment at the plant or during maintenance and repair operations in the field, the zinc alloys frequently provide better or equal performance at lower cost. The ZA Alloys The ZA alloys are a family of three high-performance zinc-aluminum alloys that compete in cost and performance with cast iron aluminum and bronze. The growing number and uses testifies to the versatility of these alloys and is encouraging their consideration in a wider range of applications. The ZA alloys are referred to as ZA-8, ZA-12, and ZA-27, the numbers corresponding approximately to the percentage of aluminum each alloy contains. ZA-8 is a permanent-mold casting alloy and is usually selected for decorative purposes; ZA-12 provides both performance and cosmetic benefits; ZA-27 offers the greatest functional strength. The term high performance ZA alloys distinguishes them and their improved engineering properties from traditional zinc die casting alloys. Maintenance Savings At its mine in Timmins, Ontario, Kidd Creek Mines Ltd. operates over 40 Joy VCR- 150 crawler-mounted air-powered rock drills. Most of the drill components undergo severe stress as the drill batters through the under-ground rock. As the components wear, the drill bits wobble; when the wobble becomes excessive, the drills are rebuilt. In the gear train, which rotates the drill steel, there are three planetary gears with - historically - bronze bushings. Since the planetary gear bushings are wear items, they are routinely replaced during overhaul. The bronze planetary gear bushings (three bushings per assembly) were replaced up to five times annually. With 43 drills in use, bushing consumption approached 600 per year. At the manufacturer's replacement part cost, the 600 bushings and gears would cost more than $20,000 a year. Even though a major saving was achieved by having the bronze bushings manufactured locally, the 600-unit annual usage provided ample incentive to investigate other ways of lengthening drill life and reducing the part costs. One approach was to consider using a bushing material that offered good bearing properties, but was lower in cost. About three years ago, ZA-12 zinc-aluminum casting alloy, costing less than half as much as bronze, was evaluated and selected for testing. One hundred ZA bushings were manufactured and placed in service as the drills came in for rebuilding. At the next rebuild the "drill doctor" (drill maintenance mechanic) noticed that, although the bronze bushings were completely destroyed, on occasion the zinc alloy bushings were not. In addition, he noted that some of the ZA bushings showed less wear than the bronze bushings. Because the bushings were changed routinely during each overhaul, the actual operating life of each bushing was not determinable. Therefore, it was not possible to statistically compare the life of the ZA bushing against the bronze. However, the desired life of the part was from overhaul to overhaul. So the ZA alloy obviously met the objective, giving equal or better life than bronze at a significantly lower price. Based on the favorable results of the testing under actual operating conditions, Kidd Creek maintenance personnel decided to switch permanently to the ZA bushings for rebuilding the VCR-150 rock drills. Original Equipment Application As one of the leading companies marketing the ZA alloys, as well as a zinc -copper-silver mining company, Kidd Creek is interested in developing applications for the alloys by original equipment manufacturers such as joy Manufacturing. Kidd Creek marketing representatives provided joy with information on the Timmins mine tests, along with ZA-12 bushings for evaluation and testing. Based on this information, joy installed ZA bushings in 12 new VCR-150 units and delivered them to customers for use in such areas as granite quarries and copper, lead, zinc, and limestone mines. During the following year, joy engineers closely monitored repair reports to verify the performance of the ZA part. The engineers' findings convinced them of the advantages of ZA-12. As a result, joy now uses ZA-12 bushings in the manufacture of its VCR-150 air tools. Advantages for Casters and Users In the foundry, the new alloys have proved their castability and profit potential in sand and metal permanent-mold processes, as well as the new graphite permanent-mold gravity casting process. The energysaving, pollution-free and ease-of-machining benefits they offer are important to all of these processes. Most recently, the high-performance alloys entered the arena of cold-chamber die casting, where they provide properties beyond those of

Jan 7, 1983

Advanced Jig Separation of Shredded Plastics The authors have reported that the RETAC jig is very useful in separating relatively low density particles such as plastics, and demonstrated that highly efficient jig separation of plastic components in discarded office machines is possible in pilot-scale tests. To further improve the separation efficiency, a hybrid jig (RETAC jig with air bubbler under the particle bed) which can separate plastics having similar specific gravities using differences in wettability produced by a pretreatment, and a reverse jig (modified RETAC jig for plastics lighter than water) were developed. This paper reviews the separation of shredded plastics using advanced jig separation technology (RETAC, hybrid and reverse jigs). Wettability control of the plastics for the advanced jig separation is also reported.

Sep 13, 2010

By K. Ramji

"The development curve in the extractive sector has become longer, steeper, and riskier due to increased social, legal, and political risks from various stakeholders. Indigenous peoples are a unique stakeholder because their growing legal rights to lands and resources can often determine a project’s outcome. A project will only be successful if it is able to obtain the legal permits, withstand any judicial reviews, and gain and maintain the social license to operate. Stakeholder identification, management, and engagement are key risk-mitigation tools required to successfully convert risks into opportunities.RÉSUMÉ La courbe de développement du secteur de l’extraction s’est allongée, elle est devenue plus abrupte et plus hasardeuse en raison de l’accroissement des risques sociaux, légaux et politiques venant des divers intervenants. Les peuples autochtones sont des intervenants uniques puisque leurs droits légaux croissants sur les terres et les ressources déterminent souvent ce qu’il adviendra d’un projet. Un projet ne pourra réussir que s’il est capable d’obtenir les permis légaux, passer à travers les analyses judiciaires, puis obtenir et maintenir le permis social d’exploitation. L’identification des intervenants, la direction et l’engagement constituent les outils clés de l’atténuation des risques nécessaires pour bien convertir les risques en possibilités."

Jan 1, 2016

By N. Reddy

The influence of local geology and rock mass characteristics on deformations during a rockburst caused by a controlled blast was studied. This was done by means of visual examination, mapping and photography both before and after the blast. We found that the ejected material was bounded mostly by fractures associated with the bow-wave fracturing and bedding surfaces and that existed prior to the blast. Most of the damage was caused by shake-out. This information is important input for the design of rockburst resistant support systems under conditions of moderate stress.

Jan 1, 2001

It is predicted that vast volumes of affected mine water will be produced by mining activities in the Mpumalanga coalfields of South Africa. The potential environmental impact of this excess water is of great concern in a water-scarce country like South Africa. Research over a period of more than 10 years has shown that this water can be used successfully for the irrigation of a range of crops (Annandale et al., 2002)1. There is, however, continuing concern from the local regulators regarding the long-term impact that large-scale mine water irrigation may have on groundwater quality and quantity. Detailed research has been undertaken over the last three years to supplement the groundwater monitoring programme at five different pilot sites, on both virgin soils (greenfields) and in coalmining spoils. These sites range from sandy soils to very clayey soils. The research has included soil moisture measurements, collection of in situ soil moisture over time, long-term laboratory studies of the leaching and attenuation properties of different soils and the impact of irrigation on acid rock drainage processes, and in depth determination of the hydraulic properties of the subsurface at each of these sites, including falling head tests, pumping tests and point dilution tests. This has been supported by geochemical modelling of these processes to quantify the impacts. The results indicate that many of the soils have considerable attenuation capacities and that in the period of irrigation, a large proportion of the salts have been contained in the upper portions of the unsaturated zones below each irrigation pivot. The volumes and quality of water leaching through to the aquifers have been quantified at each site. From this mixing ratios have been calculated in order to determine the effect of the irrigation water on the underlying aquifers. Keywords: coalmines, irrigation, gypsiferous mine water.

Jan 1, 2009

To reduce the respirable dust generated by auger-type continuous coal mining machines. The Approach: Use water sprays close to the cutting bits on the auger so that coal fragments are thoroughly wetted as they are formed to prevent dust dispersal into the ventilating air. How It Works: The "wet auger" system of dust control uses water sprays distributed on both shafts of auger type continuous miners. This approach has been tested underground by personnel of the Bureau's Twin Cities (Minn.) Mining Research Center on a Wilcox Mark 20 continuous miner, in a cost sharing contract with Buchanan & Sons Coal Company, Inc. Personnel of the Interior Department's Mining Enforcement and Safety Administration collected dust samples and analyzed the data. A test machine was fitted with six sprays on each auger (see Fig. 1). Water flow rates from 8 to 12 gpm at pressures from 90 to 120 psi, or about 8 gallons per ton of coal mined, were required. At these rates of water usage, mining personnel experienced no problems with work-

Jan 1, 1974

By G. L. Fitzpatrick

A portable optical instrument for performing multispot laser vibrometry is described. The instrument is capable of measuring arrival times, surface motion frequency, and surface velocity and displaying these quantities in various useful ways. Sigma Research is currently pursuing the development of such optical measuring systems for the evaluation of structures in rock by non-contact interferometry methods. This work was sponsored by the U.S. Department of Interior (U.S. Bureau of Mines) under a Small Business Innovation Research (SBIR) contract number J0145075. The goal of the work was to develop a portable tripod mounted measuring system which can be set up at arbitrary distances (up to 30 meters) from a surface and project four in-line laser sample beams on this surface. A light receiving telescope gathers the scattered light from these four spots and provisions are made to mix this light with a reference beam from the laser. Four photodiodes are employed to determine the resultant interference signals which characterize the motion (particle velocity, frequency, amplitude) of the four illuminated spots on the surface under sudy. Information of this type can then be used to characterize the elastic or mechanical properties of the surface in question. In some cases (if more than four spots are involved) this surface information could be back propagated to draw inferences about the internal state of the material volume bounded by this surface.

Jan 1, 1987

Electrical trailing cable used to power coal mining machinery is frequently damaged by tensile strain or crushing by mining machines running over the cable. A major problem is finding the exact location of a short or open in this cable so it may be repaired. A major problem is finding the exact location of a short or open in this cable so it may be repaired. FMC Corporation was awarded modification III to USBM Contract H0122011 to continue development and testing of cable fault locators, resulting in delivery of: 1. A prototype electrostatic/electromagnetic/ TDR transmitter and an electrostatic/electro-magnetic receiver sot that: o Locates cable faults by time domain reflectometry o Locates opens by detecting electrostatic signals o Locates shorts by electromagnetic coupling. 2. A prototype infrared detector and an infrared detector power supply that heats a shorted area by applying high current (at low voltage) and locating a short by infrared output. 3. Twelve production infrared detectors. 4. Detail drawings for all of the developed instruments.

Jan 1, 1973

By Anthony B. Szwilski, Dalip Sarin, Richard D. Begley

This paper will present the results of an analysis of several abandoned coal mine projects and includes field data for over a dozen different reclamation projects recently completed in the state of West Virginia. The analysis was performed with the objective of summarizing and or classification of the environmental consequences with reference to the characteristics of the mining facilities (surface, underground, etc.). The analysis also addressed the itemized cost of remediation with respect to procedures, environmental concerns and time. The results of the analysis are that each abandoned coal mine site in West Virginia have/had many unique features and in most cases include a combination of environmental concerns that complicate comparisons. The study also revealed that the abandoned mine land program for mines abandoned prior to 1977, that is being financed by a tax on the production of coal, has produced many benefits for the state of West Virginia. This grant program administered by the Office of Surface Mining, has resulted in a high quality methodology of remediation that has been successful for many years in greatly minimizing and/or eliminating environmental concerns from abandoned coal mines.

Feb 24, 1997

By Paul Hosford, Tim Haldane

"The paper describes the fast-track development of the project from feasibility study through to detailed design and construction, highlighting the process adaptations for handling sticky ore and water management in a tropical environment, and subsequent commissioning and operating experience of the mine. The paper discusses the geological setting, the environmental and socioeconomic considerations in developing and operating a mining operation in an underdeveloped country and the logistical challenges involved in bringing a large capital investment into Central America.INTRODUCTIONGlamis Gold Ltd. acquired the San Martin project in Honduras as a result of its merger with Mar-West Resources in late 1998. Despite the prevailing low gold price environment at the time of acquisition, Glamis anticipated rapid development of the San Martin project due to the quality of the deposit and other positive factors.Following favorable exploration and permitting activities in the first half of 1999, Glamis prepared a Feasibility study. In October 1999, Glamis decided to proceed with the development of the project and selected Hatch to provide the engineering, procurement and construction management services for the project. The San Martin project was in full-scale commercial operation approximately 14 months after the receipt of Board approval, and by July 2001 the San Martin project was operating at approximately 150% of its feasibility design capacity."

Jan 1, 2002

By R. Stefanko

This study concerns itself with the effects of diesel exhaust on mine ventilation systems. The approach here consisted of the development of mathematical models for emissions, dilution, and dispersion of gaseous pollutants from diesels. The general scheme was to use partial differential equations to predict concentration growths. Specifically, the following situations were modeled: 1. A single stationary diesel engine working in a single roadway. 2. A single diesel engine moving with uniform velocity in a single roadway. 3. Multiple diesel engines moving continuously in a cycle in a roadway with appreciable leakage. 4 Multiple diesel engines moving continuously in a cycle in a roadway with little or no leakage. 5. Multiple diesel engines moving randomly in a roadway with uniform air velocity.

Jan 1, 1974

By P. Share

As part of JAGUARS (JApanese-German Underground Acoustic emission Research in South Africa), high-resolution tiltmeters were installed during 2007 at Mponeng gold mine, South Africa, in an attempt to study and understand the risks posed by in-mine seismic events and to subsequently use the knowledge gained to mitigate these risks. In December 2007, an M2.2 event occurred at Mponeng and was detected by the tiltmeters installed. The tilt expected for the M2.2 event is modelled through the use of numerical and analytical tools and utilizing, as input parameters, characteristics of the event such as the rupture area, the amount of slip, elastic properties of the rock, the state of stress before the event occurred, and frictional parameters of the rupture. The calculated tilt values are correlated and compared with the recorded data, and are found to be of the same order. Certain input parameters, such as the initial rupture point, are further constrained by varying them, during modelling, until the calculated and observed tilt values are approximately equal. From modelling, it can be concluded that the rupture point had to be closer to the location of the tiltmeters. In addition, possible locations acting as source areas for the observed aftertilt are determined. Further modelling still needs to be done to quantify the effects of the tunnel close to the tiltmeters and plastic deformation of the rock mass. Keywords high-resolution tilt data, Mponeng gold mine, M 2.2 seismic event, analytical modeling, numerical modeling, rupture plane.

Oct 1, 2013

By E. G. Davis

As a result of interest by the U.S. Department of Energy, the Bureau of Mines conducted studies on comminution of bituminous coal to the 2-um particle size range using the Bureau-developed turbomill. Both "plant grind" size (80 pct minus 75 um) and microsize (minus 10 um) coal can be produced in a single step with the Bureau's turbomill. In 15 min, minus 2.4-mm coal milled in water with steel shot was reduced tc 65 pct minus 75 m and 26 pct minus 2 m, with an energy requirement of 139 kW^h/mt coal. Plant-grind size coal milled in water, with Ottawa sand as the milling medium, was reduced to more than 45 pct minus 2 m in 15 min, at 175 kW?h/mt. Plant-grind coal milled with steel shot was reduced to 57 pct minus 2 um in 15 min, at 138 kW?h/mt. When diesel fuel was substituted for water, the milling of the coal was less effective and less energy efficient. Keeping the pulp dispersed was critical. Without an effective dispersant, the slurry became very viscous with increased milling time, resulting in higher energy requirements, low heat dissipation, and poor grinding efficiency.

Jan 1, 1987

By John C. Nigro

This Bureau of Mines report summarizes the performance characteristics of a 30-day around-the-clock gasification-pelletizing test conducted in October and November of 1980 with North Dakota Indianhead lignite. Gasification was conducted in a commercial-size, 6.5-it-diam, Single-stage, fixed-bed, atmospheric pressure producer with a rated capacity of about 30 million Btu/hr. Iron oxide pellets made from a commercial hematite concentrate were fired with the low-Btu gas in a 2.8-ft-diam by 35-ft-long pilot plant rotary kiln at a rate of 900 lb of pellets per hour. Gasifier operations at fuel feed rates up to 3 tons of lignite per hour and hematite pellet induration with raw 160-Btu/std ft3 lignite gas are described.

Jan 1, 1982

By A. Garassino

A pile design was performed for a thermal power station in Egypt and more than 4000 piles were to be driven. Technical economical reasons suggested the choice of driven composite LACOR piles designed for very high specific loads. Some uncertainties on the behaviour of the pile soil system suggested to perform a test on an instrumented pile. Scope of the test was to verify the possibility of developping the required bearing capacity within the range of the allowable pile settlements values and the effect of the pile joint enlargement on that portion of skin friction to be developped by the upper pile section.

Jan 1, 1991

The principles of geometry and trigonometry are so continuously used by mining engineers for the purpose of accurately and intelligibly recording their measurements, that the writer is prompted to lay the following cursory remarks upon mine surveying before the members of this Institution in the hope of eliciting a free interchange of opinion upon details of this interesting branch of the profession. He proposes to deal with surveying only so far as it concerns the mining engineer, not to intrude upon the domain of the professional surveyor, and, in this instance, to discuss more especially that which may be termed the mechanical, rather than the mathematical side of surveying.In the latter part of the eighteenth century and the beginning of the present one, the usual underground surveying equipment in the English metalliferous mines, consisted of a magnetic needle in a fiat square wooden box of about 9-inch sides, a two-foot rule, a long cord, aud a stool, upon which to place the needle and box. The operator took his bearing by sending his assistant with the end of the cord as far in a straight line as the length of the cord would admit.On its being drawn that he held its end in one hand and placed the side of the compass-box against it with the other, and noted the bearing thus found either by a book entry, or by ticking it off with a piece of chalk on the board the compass lay in. He then measured the cord with a two-foot rule. It is needles to say that with these appliances the accuracy of the results were open to question, and mining surveying was not unduly popular.In the present day, engineers have the advantage of using instruments brought to such a state of perfection, and of employing such an exact system of underground surveying, that inaccurate work must usually be attributed either to lack of care, or lack of ability in the operator.

By Eric E. Cather

A mineral survey of a portion of the Lake Eleanor RARE II area (No. 5807), Trinity County, California, was done by the U.S. Bureau of Mines and U.S. Geological Survey (USGS). Approximately 8,650 acres (3,500 ha) of the Lake Eleanor RARE II area not examined for this report had been previously investigated by U.S. Bureau of Mines and U.S. Geological Survey personnel and published as part of USGS Bulletin 1371-B, (Hotz, 1972) Mineral Resources of the Salmon-Trinity Alps Primitive Area, California. The report showed that the section included in the rake Eleanor RARE II area contained no metallic mineral resources. Geochemical sampling indicated that the Lake Eleanor RARE II area contains no potentially important mineral resources. About 4,650 acres (1,880 ha) of the eastern part of Lake Eleanor RARE II area were examined for this report. The Bureau of Mines was responsible for detailed examination and sampling of mines, prospects, and mineralized zones; the Geological Survey conducted geological, geochemical, and geophysical studies of the area. This area is underlain mainly by granitic rock and serpentinite.

Jan 1, 1981

"In mining operations, it is widely accepted that strategies to drive operational goals must revolve around improving plant availability, reliability and process efficiency. In this paper, an integrated solution framework for reducing process variability, increasing process efficiencies and maximizing plant availability and reliability is discussed within the context of a typical milling circuit. The framework exploits a real-time analysis “gap” evident in production operations that prevents timeous identification of equipment and process failures. This is achieved by leveraging predictive analytics for equipment health monitoring, control loop monitoring and advanced regulatory control solutions towards enhanced process performance, improved asset management and regulatory compliance. The framework provides for early and actionable warnings on equipment and process degradation using real-time operational data.INTRODUCTION The changing landscape of gold mining and processing presents many challenges that threaten sustainability of existing (marginal) operations as well as deter investment in new projects. As existing “shallow” ore resources become depleted, mining operations are increasingly treating low-grade ores with complex and randomly variable mineralogical characteristics. For example, in South Africa, historically one of the major gold producers, the average grade of ore treated has been decreasing from averages above 4.5 – 5 g/t to current grades averaging less than 3 g/t within a decade (Chamber of Mines, 2012). Moreover, lower tonnages are being treated as a result of the narrowing of the available resource base. Also, the regulatory framework has tightened over the years due to heightened concerns on the safety, health and environmental impacts of mining and related activities."

Jan 1, 2014

By T. H. Jeffers

The U.S. Bureau of Mines has developed porous beads containing immobilized biological materials for removing metal contaminants from waste waters. The beads, designated as BID-FIX beads, are prepared by blending biomass, such as sphagnum peat moss or algae, into a polymer solution and spraying the mixture into water. Laboratory studies were conducted to determine bead sorption and elution characteristics. Batch and continuous tests demonstrated that BIO-FIX beads sorbed arsenic, cadmium, lead, and other toxic metals from acid mine drainage waters collected from several sites. Selectivity for heavy and toxic metal ions over calcium and magnesium was demonstrated. The beads exhibited excellent metal sorption and handling characteristics in stirred tanks, column contactors, and a low-maintenance passive system. The sorption process was reversible, and metal ions were eluted from the beads using dilute mineral acids. Cyclic tests indicated that the beads continued to extract metal ions after repeated loading-elution cycles.

Jan 1, 1991