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By S. R. Borrowman

Mill tailings from conventional uranium extraction processes contain nearly all of the radium originally in the ore. Such tailings require controlled storage in perpetuity to safeguard the surrounding environment from radioactive contamination. Alternatives to controlled storage of the tailings are (1) removal of the radium from the tailings for separate storage or use or (2) removal of the radium when processing the uranium ore. In laboratory tests conducted by the Federal Bureau of Mines, radium was leached from tailings using either hydrochloric acid or ethylenediamine tetraacetic acid. A hydrochloric acid leaching method was used to extract both radium and uranium from the ore to yield tailings containing less radium than those produced by either conventional sulfuric acid or alkaline leaching processes. From 77 to 94 percent of the radium in mill tailings was concentrated by sedimentation in slime fractions representing nearly 25 weight-percent of the original sample.

Jan 1, 1975

By P. H. Rodriguez

The aquatic hazard classification system of the OECD and EU requires that sparingly soluble metal substances (SSMS) be tested using the OECD Dissolution/Transformation protocol in order to quantify the release of the ecotoxicological relevant species (dissolved ions). The SSMS category contains massive forms of metals, which due to their low solubility and slow transformation characteristics are a special case. The main factors that produce the release of metal into solution are exposed surface loading, pH, and stirring rate. The classification system at present prefers the use of mass loading as opposed to surface loading, in which case the amount of metal released will primarily be a function of the pH, and mass loading. Within the framework of the European Copper Voluntary Risk Assessment, coordinated by the European Copper Institute, we have proposed and developed a methodological procedure in which we demonstrate that surface area is an intrinsic property of a SSMS and we link the exposed surface loading to the toxicity reference value in order to obtain an aquatic hazard classification for massive metals. As example, the aquatic hazard classification for copper massive will be discussed. This approach is recommended for metal massives and metal powders.

Jan 1, 2007

By Potts J. D.

Installation of a horizontal air-blocking shelf around the inside perimeter of the surface mining drill deck shroud is proposed to improve dust capture. Without the use of this shelf, a strong Coand? effect airflow pattern results in dust leakage to the environment, especially at the shroud-to-ground interface. Bailing air exits the drill hole and travels along the drill steel to the underside of the table, where it fans out across the bottom of the drill table and continues down the sides of the shroud. This dust-laden bailing air then strikes the ground and fans out under gaps between the shroud and the ground. The proposed shelf prevents dust-laden air from striking the ground by redirecting it toward the center of the enclosure, where it can be captured. Laboratory tests demonstrated that the shelf reduced dust levels outside of the shroud by 81% under operating conditions consisting of a 1.9:1 collector-to-bailing-airflow ratio and a 51-mm (2-in.) gap between the shroud and ground. The shelf was 152-mm (6-in.) wide and was located at a height equal to 2/3 the distance measured from the bottom of the shroud to the bottom of the drill table. The air-blocking shelf was also capable of overcoming the adverse impact of vertical leakage along the shroud seams as long as this leakage was confined to an area below the horizontal plane defined by the shelf location.

Jan 1, 2008

By Daniel A. Jones

The Surface Mining Control and Reclamation Act of 1977 establishes a nation-wide program requiring the Secretary of the Interior, through the Office of Surface Mining Reclamation and Enforcement, and the States to protect against the adverse effects of coal mining and to reclaim previously mined lands left without adequate reclamation. The Act requires coal mine operators to: restore the land to approximate original contour, return the land to a condition capable of supporting prior potential uses, protect the hydrologic balance, segregate and restore topsoil, control blasting to prevent damage and injury, establish vegetative cover, and control surface effects of underground mining. The Act also establishes: a reclamation fee on coal, a program to assist small operators, a program to give technical and financial assistance to State programs, State Mining and Mineral Research Institutes., a program for designating areas as unsuitable for mining, and a study on surface mining of minerals other than coal.

Jan 1, 1977

By Adam K. Smith

Over-exposure to noise remains a widespread, serious health hazard in the U.S. mining industry despite 25 years of regulation. Most other categories of illnesses and injuries associated with mining have improved, with the exception of hearing loss. In order to reduce cases of Noise Induced Hearing Loss (NIHL) in the mining industry, retrofit acoustic treatments and controls are being developed to subdue noise at the source. The Mine Safety and Health Administration (MSHA) coal noise sample data collected from 2000 to 2005 has determined that continuous mining machines rank first among all mining equipment whose operators exceed 100% noise dosage. The continuous mining machine conveyor, used to move coal from the cutting face to the rear of the machine, has been identified as a dominant noise source. A dual sprocket conveyor chain was tested as a potential solution. Sound power level measurements conducted at the Pittsburgh Research Laboratory (PRL) accredited reverberation chamber showed a 3 dB reduction in the A-weighted sound power level when the dual sprocket chain was implemented. Underground results show an 8-hour Time Weighted Average (TWA8 hrs) reduction a 3 dB for continuous mining machine operators. Utilizing this newly developed noise control, along with previously proven controls, provides continuous mining machine operators an opportunity to be within the MSHA-Permissible Exposure Limit (MSHA-PEL).

Jan 1, 2009

By Andrea Biagi, Elisa Comis, Gianluca Bella, Enrico De Panicis, Guido Barbieri, Matteo Giani

The Sotra Link Project is a major infrastructure project in Norway involving the design, construction, financing and maintenance of several underground and surface structures between Sotra island and the city of Bergen, among them 23 tunnel portals, 12.5 km of tunnels and a 900 m long suspension bridge. This paper describes the benefits in applying a Building Information Modelling (BIM) approach to tunnelling, from Early Design to the Detail Design Phase. The BIM application to the Sotra Link Project resulted in several improvements, such as efficient handling of clashes and inconsistencies, deeper understanding of effective design choices (reduction of errors), more efficient communication between designers, enhanced control of project quantities and costs. The advantages of the BIM approach during the ongoing Construction Phase are also explained.

Jun 23, 2024

By Raymond B. Ladoo

Toward the end of 1920 , the average grades of ground feldspar offered to the pottery industry were so poor and so generally unsatisfactory that many of the largest consumers decided to take active steps for their own protection . A few of the potters made arrangements to grind their own feldspar , while others asked the Bureau of Mines to make a detailed study of the problem and to suggest methods of improvement . Accordingly such a study was undertaken, the partial results of which are outlined in this preliminary report . The outstanding features of the present feldspar industry which are of interest in this connection are stated below. (1 ) Many grinding companies do not own or control all or even a major part of their sources of crude material , but buy in job lots from many sources . (2 ) There is great need of more adequate engineering and chemical control over mines and mills . ( 3) ~ Out of date , inefficient methods and equipment for mining and grinding are in common use . (4) Little or no cooperation exists between feldspar producers , but on the contrary many feldspar companies are exceedingly secretive . This tends towards (a) preservation of obsolete methods ; ( b ) want of knowledge of the essential features of production , market requirements , and the relation between total milling and consuming capacities of the country; ( c ) inefficient and often mistaken trade practices ; ( d) unprofitable and even ruinous competition in dull periods . (5) The small size of many feldspar deposits precludes maintenance of an efficient organization at each individual mine . ( 6 ) Many of the best deposits of feldspar situated close to railroads are becoming depleted , which results in gradual lowering of grades , and increase in cost for better grades . (7) There is a lack of exact mowledge of the ceramic properties and behaviour of feldspar by some consumers , which results in ( a) purchase of feldspar on the basis of price alone , thus encouraging low production costs at the expense of quality , and ( b) inefficient and expensive cross- hauling of both crude and ground feldspar .

Jan 1, 1922

By Rob Thomas

It is generally agreed that standing support should be installed in roadways that will for various reasons, be holed through with a longwall. Considering the magnitude of the associated abutment loading in conjunction with the need to ensure that the material used is cuttable, some form of cementitious support is often used.

By D. Wenstrup, K. Perry, J. Hatfield, P. Sainato, B. Lusk

Concrete-infused cloth is used in several civil and mining surface applications whose circumstances are similar to some of those in underground mining. A feature of this material is that it cannot be overhydrated. In underground conditions, however, the excess supply of water to the cloth for hydration could lead to muddy and potentially unsafe working conditions, as well as resource wastage by supplying more water to the construction site than is needed. The objective of this study is to verify the water-to-cloth ratio and study the effect of hydration level on the strength of the Concrete Cloth product. We found that the strength increases with increased hydration up to a 1:2 water-to-cloth ratio by weight, after which the strength holds steady regardless of additional hydration. This confirms the 1:2 water-tocloth ratio by weight for hydration and confirms that strength is retained even if the cloth is excessively hydrated.

Jan 1, 2014

By G R. Ballantyne, M S. Powell

A comprehensive Australia-wide survey of comminution energy consumption at copper and gold mines was presented by the authors at the 11th AusIMM Mill Operators’ Conference 2012. The database has been extended to include major overseas mines and used to benchmark comminution energy consumption across the industry. The mines included in this study now represent 15 and 24 per cent of the total global gold and copper production respectively, and almost all Australian production. The comminution energy intensity per unit of saleable metal has been presented in a graphical form similar to a cost curve used in economics. The graphical method has been developed to assess the competitive advantage that can be achieved by reducing comminution energy intensity.This benchmarking tool has been applied to three published case studies to assess its applicability. The first case study indicated that a large reduction in size-specific energy (kWh/t -75 µm) was achievable by converting standard semi-autogenous and ball mill circuits to include high pressure grinding roll and stirred mills. The second case study investigated the metal-specific energy reduction historically achieved by Bougainville with the addition of a preconcentration screening plant. The final case study was conducted by Barrick Gold Corporation and involved incremental efficiency upgrades at three of its gold mines: Cortez, Cowal and Mara North. The application of the benchmarking tool to each of these case studies successfully demonstrated the scale and competitive advantage that was achieved by reducing energy intensity.CITATION:Ballantyne, G R and Powell, M S, 2014. Benchmarking comminution energy consumption for improved efficiency, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 95–100 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By Nabil F. Ismael, Khalid Farraj

"The axial load transfer along large diameter bored piles in very dense silty sand was examined by field tests. Two instrumented piles 1.2 m diameter and with embedded length of 18 m and 25 m were load tested in axial compression to failure in connection with the construction of a big tower building in Kuwait City, Kuwait. Instrumentation included vibrating wire strain gages at various levels, displacement transducers and extensometers. The purpose being to measure the axial load distribution, skin friction, and base resistance at various load levels. In addition the settlement of the piles and the elastic compression were monitored. The ultimate pile capacity, side friction, and base resistance were determined and correlated with the Standard Penetration Resistance values as determined from the boreholes. Most of the load was transferred as side friction and the pile settlements at the maximum loads ranged from 1.6% to 2.2% of the pile diameter.INTRODUCTIONLarge diameter bored piles are used with increasing frequency for heavy structures in Kuwait and the Gulf region in calcareous sand. The behavior of short piles ranging in depth from 8 m to 15 m was examined by field test (Ismael 2012). However, larger diameter and deeper piles are being used more frequently, including the project described in this paper which included piles with 1.2 m diameter and 18 m to 25 m depth. The design of these piles requires knowledge of the skin friction and point resistance in these soils. While field tests on driven piles are available (Ismael 1989, Ismael 1999), field test data on long large diameter piles installed through very dense sands or silty sands are very limited at present. The results of two load tests carried out recently on instrumented bored piles at one site in downtown Kuwait City have become available. In these tests the failure load was extrapolated from the test results. It is important to examine and analyze the test results for the benefit of the geotechnical research and design engineers."

Jan 1, 2017

By D. L. Boreck

With increasing land development, the potential of fatalities from abandoned mine shafts increases. To minimize potential liability, shaft closure should be a critical part of mined land reclamation. The Bureau of Mines is conducting research into using lightweight foam concrete in sealing abandoned coal mine shafts. A demonstration seal consisted of a 3m thick foam concrete plug to provide lateral stability inside the shaft. A high density concrete cap provided load-bearing capacity for a 100-year service life. The USBM has also completed research into changes in foam concrete when it is pumped or dropped from different heights. It is concluded from the research that foam concrete can undergo significant air loss with pumping or dropping. This foretells significant changes in the characteristics of the concrete as well as an increase in the weight and cost of the in-place concrete seal. When using foam concrete to seal abandoned mine shafts, care must be taken to minimize air loss during placement.

Jan 1, 1994

By Susan E. Brink

The first step in determining whether Mn can be recovered by in situ leaching is to develop and test a selective lixiviant. Two column leach tests and one core leach test Were conducted by the U.S. Bureau of Mines on Mn oxide ore using aqueous sulfur dioxide (SO2) as the lixiviant. The column tests showed that aqueous S02 could selectively dissolve available Mn oxides from calcite-rich ore in a heap leach system. However, the core test showed that calcite gangue side reactions can have pronounced negative effects on the likelihood of successful in situ leaching of a calcite-rich ore with aqueous S02. Petrographic and geochemical analyses showed that both Mn (IV, III) oxides and calcite were dissolved. The abundance of dissolved Ca caused precipitation of gypsum. Acid consumption by calcite dissolution caused a rise in pH that caused the SO/S species to shift to S032-(sulfIte), which hindered reductive dissolution of Mn oxide. Gypsum precipitation did not affect complete leaching of the rock fragments in the column tests; however, it plugged the natural permeability in the core. Manganese recoveries were high for the column tests and low for the core test.

Jan 1, 2010

By Aixiang Wu, Minjie Zhang, Zhuen Ruan, Yiming Wang

This paper combines theoretical and experimental analysis to conduct relevant research to improve the accuracy of predicting paste yield stress by slump flow. The analytical model of slump flow for yield stress is derived based on a mini-cylindrical mold with a height-to-diameter ratio of 1. It shows that the dimensionless slump flow is a monotonic decreasing function of the dimensionless yield stress and is independent of the material type (specific gravity), which provides a theoretical basis for quantifying the rheological properties of paste with slump flow. Three different tailing-prepared pastes were tested for their slump flow and implemented rheological tests simultaneously. The yield stress is obtained based on the Bingham model fit, as the measured value of the yield stress is substituted into the derived theoretical model. The studied pastes yield stresses range from 34.78 to 524.08 Pa, with corresponding dimensionless slump flow of 3.43 to 1.09. The results showed that the calculated slump flows were generally greater than the measured values. The analysis showed that this was mainly due to the thixotropy of the paste, with minor deviations ranging from − 1.5 to 5.8% for the less thixotropic pasted prepared from tailing C. An approximate analytical solution for yield stress as a function of slump flow is obtained using Taylor’s formula. However, it is unsuitable for predicting the yield stress because the yield stress calculated by this function is much higher than the measured value. The empirical yield stress model was constructed and experimentally verified. The results show that the empirical formula has high accuracy and good generality. The deviation of the studied pastes is between − 15 and 5%, which provides a practical method for rapid and accurate prediction of paste yield stress in mine sites.

Jun 1, 2023

By Kevin W. Harris

Multiple-seam coal mining is a major issue in underground coal mining that adds additional complexity to the practice of ground control. As reserve exploitation is driven by economics, it is now difficult to mine coal without the existence of previous workings above and/or below the active seam; this is particularly true in the Appalachian coalfields. The frequency in which problematic multiple-seam interactions are now encountered has resulted in significant research regarding the underlying mechanisms of the problems and methods of mitigation. In the last few decades, a great deal has been learned about these interactions and the ability to minimize problems associated with these hazards has greatly advanced, resulting in better economics and improved safety. Minimizing the adverse effects of stress interactions often requires a thorough understanding of site-specific geotechnical parameters and previous mining geometry. This is especially evident in bump-prone ground, where pillar behavior is highly dependent on local conditions. This paper presents a case study in a deep cover, Central Appalachian coal mine where three bump events occurred. Initially, empirical design software was used in an effort to analyze the situation and prevent further instability. The empirical study proved ineffective. A detailed investigation of the bump events using the boundary element software LaModel 3.0 was then performed. This study resulted in a site-specific calibration standard that will be applied in numerical pillar design for the remaining reserve.

Jan 1, 2014

By Rob Thomas

"In Australia, a wide roadway is commonly defined as any roadway that is driven to a width greater than 5.5 m (18 ft). These roadways are typically required to enable the installation of longwall equipment (termed installation roads); however, other applications include the need to house conveyor driveheads and pre-driven recovery roads.As a result of the increasing size of longwall equipment and mine infrastructure, in some mines, roadway widths of between 9 and 12 m (30 and 39 ft) and are being developed.Accepting that these almost always constitute strategically important and often long-term roadways, this paper considers the use of: (i) an empirical roof support design model, which is based on over one hundred case histories, (ii) various roof support design principles, and (iii) commonly accepted strata management techniques.The paper demonstrates that wide roadways can be driven and supported to an acceptable standard providing due consideration is given to the prevailing ground conditions (including the quality of the immediate and upper roof strata, the Depth of Cover and the horizontal stressfield), the final width of the roadway and the required use of the roadway.INTRODUCTIONRoof behaviour and the associated roof support requirements in wide roadways, which are roadways typically driven to a width that is greater than 5.5 m (18 ft), are controlled by a number of key geotechnical and operational factors. The recognition of these factors is an important first step in the design process and it is imperative that each is considered in conjunction with local mine site information.The main points of note in this regard can be summarised as follows:• The greater the final width of the roadway, the greater the resulting surge in roof displacement on widening - note: a) see Figure 1 for a schematic illustration of the roof displacement trends typically measured during the development of the first pass and roadway widening, b) since displacement increases with roadway width, it is always recommended that the roadway width is kept to the minimum required and c) general buckling beam theory indicates that the capacity of any beams present in the roof will reduce in inverse proportion to any increase in roadway width squared (i.e., [final width2 -first pass width2] I final width2)."

Jan 1, 2010

By AIME AIME

The first Diesel-electric locomotives for the Mesabi iron range of the Lake Superior district were put into service last summer by the Oliver Iron Mining Co., U. S. Steel subsidiary. There were ten of these locomotives, rated 1000 hp. and weighing 125 tons each. They are designed for service from 16 to 24 hours per day to haul trains of loaded ore cars from open-pit mines, 200 to 400 ft. deep, on a two to eight-mile haul to the top of the pit. The locomotives push or pull the trains over switchbacks and up heavy grades with 5 per cent maximum against the load. High tractive effort, less smoke, and ability to negotiate sharp curves were among the reasons for the selection of Diesel-electric locomotives.

Jan 1, 1941

By AIME AIME

EDWIN W. KEMMERER, professor of international finance at Princeton, in a speech before a banking conference at Urbana, Ill., on Nov. 26, stated that the increase in the store of gold held by the United States is not so alarming as it appears on the surface. Excerpts from his address, as reported by The New York Times, follow: "It is significant . . . that the value of gold as expressed in its purchasing power in the United States during the last half-dozen years has been higher than at any other equivalent period since our records began 140 years ago. Our so-called 59-cent dollar today buys about 25 per cent more goods at wholesale than did our old dollar in the prosperous year 1926, and an ounce of gold will now buy considerably more than twice what it did then. This present high value of gold is one reason for its recent large production.

Jan 1, 1941

By W. J. Tough

THIS paper offers examples of some of the typical calculations which occur in the ventilation of metal mines. The fi.rst section of the paper discusses the problems associated with natural-draft pressure; the second section presents the more common of the calculations concerned with the operation of mine fans; the third section illustrates the integration of the individual problems covered by the preceding sections into the larger problem of determining the operating characteristics of a fan for a particular mine duty. There is a very definite limit to the extent to which pure arithmetic can be successfully applied to the solution of min<; ventilation problems. As mines advance from the exploration, development, and initial production stage to the rime when underground workings become exceedingly complex, there is a considerable increase in the relative importance o theory and judgment in the solution of ventilation problems. These calculations illustrate the application of mathematics to ventilation, but they also in-elude examples of instances where arithmetic cannot be conveniently applied, and important estimates, based on judgment compounded of experience and a knowledge of the theoretical consideration involved, must be made. The inclusion of such estimates is intended as a guide and a warning to the reader; a guide in assisting him to recognize and estimate his own incalculables; and a warning that the solutions must not be blindly applied to his apparently similar problems. These sample calculations are intended to assist the reader in applying the theory contained in the standard texts on metal-mine ventilation. They have been selected from the ventilation experience of a British Columbia mine.

Jan 1, 1942

By P. E. Cavanagh

THIS REPORT is not intended to be a ?comprehensive survey of the steel industry in Europe. For the past ten years the Ontario Research Foundation has been interested in several developments in the steel industry in Europe which it was felt would be of particular interest in Canada and might possibly find application in this country. This is an account of the present status of some of these developments. The economies of steel making in Canada are somewhat different than in the United States because of the nature of the market and the relative costs and availability of such raw materials as metallurgical coke and electric power. There are cases in Europe where a great deal of effort and money has been spent in trying to make steel profitably by methods which take advantage of locally available and cheap raw materials by modifying standard practices. ln cases wl1ere the investigations have been successful and the data are available to allow translation of the results into Canadian conditions, it is felt that such information may be of great benefit in the future in Canada and at !east should be known to all those in the steel industry in this country. The field to be covered in this report only comprises the steps from concentration and treatment of iron ores to production of iron and is only concerned with those commercially operating processes well known to us and judged to be of present interest in Canada.

Jan 1, 1957