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By Jeroen van Eldert, Daniel Johansson, Henrik Ittner, Håkan Schunnesson

"Numerous aspects of underground construction, from structural stability to construction costs, depended on the tunnel quality, including blast damage and the Excavation Damage Zone. Accurately quantifying the extent and severity of damaged rock is a problem. Recent technical developments in the field of Measurement While Drilling (MWD), including software for on-board logging and on-site analysis, have shown potential for rock-mass characterization. Ground Penetrating Radar (GPR) and P-wave velocity measurement have also improved and show similar potential. This paper explores the use of MWD, GPR and P-wave velocity measurements and uses them in techniques for excavation damage characterization and prediction. The paper is based on data collected from a small underground waste-collection site in central Stockholm, Sweden. The data is correlated against rock-mass characteristics and their responses are evaluated. Results indicate potential for excavation damage characterization for all tested techniques, which could minimize blasting damage and improve the over-all tunnel quality. 1 INTRODUCTION During underground excavation the rock mass is influenced in many ways. The Excavation Damage Zone (EDZ) is a result of these influences. The EDZ can be defined by an irreversible change in rock mass properties, for example increased permeability. EDZ is influenced by the excavation method, the rock mass properties and the in-situ stresses in the area of the tunneling. Since the 1990s research has been done on the EDZ by Emsley et al. (1997), Christiansson et al. (2005), Olsson et al. (2009), Ouchterlony et al. (2009), Ittner et al. (2014), and Siren et al. (2015). Based on past literature the EDZ have in this paper been separated in the following subzones: 1. Failure Zone or over-break is the area outside the planned tunnel profile, including the Look-Out and hole deviation. This zone consists of fracture networks (both natural and blasting-induced), that caused rock fall-outs. The extent of the over-break can be determined by volumetric scanning and photogrammetry and the half cast factor can be used as a damage indicator. 2. The Damaged Zone is split into three parts and but the quantity and depth of damage is difficult to measure. Although it can be visualized by sawing of rock slices in the tunnel wall (Olsson et al. 2009), diamond coring (DC) or P-wave velocity reduction (Jern 2001): a. Inner Damage Zone (Crush Zone): It is located directly around the drill hole, and is caused by the shock-wave energy of the detonation. The micro fractures in the Crush Zone produce a white-wash (rock dust) in the half cast. b. Transition Zone: This zone consists of micro fractures that connect and form macro fractures, both radially and parallel to the tunnel wall. The macro fractures are caused by the gas expansion during the detonation of the explosive; it increases the pressure in the (micro) fractures and creates the macro fractures. Seismic reflection, rock slicing and core drilling can be used for the examination. c. Progressing Zone: In this zone the existing radial fractures propagate due to the increase gas pressure inside these macro fractures. Examination methods are seismic reflection, rock slicing and core drilling. In addition, the Peak Particle Velocity (vibrations) could be used to estimate the depth (Tesarik et al. 2011)."

Jan 1, 2016

By R. D. Call

During the past fifteen years considerable progress has been made in the technology of slope design. It is possible to design rational slope angles if suitable data on geology, hydrology, and rock properties are available. It is of course preferable to conduct a full scale slope design study, but there are those situations where a full scale study is not feasible because of time and budget constraints. In this paper we will treat two situations: (1) choosing slope angles for a preliminary feasibility study at the exploration stage; and (2) dealing with a slope failure in an operating pit. In these instances slope angles must often be chosen on the basis of available or readily obtained data. In an exploration program all too often a feasibility study is initiates just a few months prior to the decision deadline to drop the property or to exercise an expensive purchase option. If all that is available at this point are a few cross sections at odd angles showing ore and waste contacts and a dog-earred map of the surface geology there may not be time to collect and organize enough information for design of slope angles. On the other hand if during the drilling program geologic cross sections are constructed and the structural data is presented in tabular form, rational slope angles can be determined within the allotted time. Certain types of data can be collected only at specific times during a project. Two prime examples are logging fracture intensity and collecting samples for rock testing before the core is split. It is particularly disheartening to ask to see the core and to be shown a tattered cardboard box filled with plastic bags of sample pulps.

Jan 1, 1976

By P. C. Clark

This paper is an overview of the requirements and concerns for minerals and pigments used in papermaking. The first part of this paper deals with mineral or pigment filling in the actual papermaking process. The second part deals with the pigment or mineral properties that are important in today's coating processes.

Jan 1, 1993

By B. Gorain

"INTRODUCTION The last few decades have seen some remarkable advancement in information technology, but recently various digital technologies have resulted in several synergies to deliver innovation in diverse applications. The mining industry has been relatively slow in adopting these technologies compared to the other industries, but this scenario is changing fast. Keywords: Digital Transformation, Operational Intelligence, Gold Recovery, Mine to Mill integration, Planning and Execution strategy, Theory of Constraints. Challenges Mining companies globally are going through a series of challenges such as declining ore grades with complex metallurgy, increasing depth of ore bodies, high capital and operating costs, lower productivity, shortage of technical resources, significant pressure from stake-holders to deliver, along with growing environmental and corporate social responsibility issues. Improvement in profitability would need significant improvements in operational performance. Consequently, over the last few years, there has been a major focus amongst some mining companies to imbibe Operational Excellence. This has been only possible because of the replacement of a silos based approach by an integrated view of the organization. Such an integrated view is now possible via the evolving digital technologies. Even so, such a transformation calls for a change in culture, which, for most organization is not trivial. Attempts in the past to integrate functions such as through Mine-to-Mill initiatives in the mining industry have demonstrated significant benefits to many operations (McKee, 2013). Still, sustaining these benefits has clearly been a challenge due to manpower turn over and lack of proper systems and structures that integrate information between business functions within an operation and between operations and the corporate.Opportunities The advent of digital technology has opened-up opportunities to integrate inter-departmental information for a unified understanding of, and across, an entire organization. The advances in instrumentation, equipment control systems, supervisory control systems (SCADA/Historian) and industrial networks have helped in the direction of enterprise wide integration. The availability of real time information across an enterprise has given rise to numerous possibilities to improve organization performance. As suggested by Seshan & Gorain (2016), some of the potential opportunities are as follows:"

Jan 1, 2018

By Adrian Brown

The primary method of slope stabilization is ground water-control. Recent research has established the properties which slope materials must exhibit in order for stabilization measures to be feasible, but there is little guidance in the literature about suitable field tests to develop the parameters needed for this evaluation. This paper presents a proven method for large scale testing which allows an evaluation of the feasibility of ground water pressure control in a reasonable cost and time frame. Methods of performance and analysis of the test are presented, and the method is illustrated by reference to case examples.

Jan 1, 1984

Crushing and grinding activity in 1989 followed the rapid pace of the mineral industry. Use of existing installations, demand for expanded capacity, and implementation of entirely new operations contributed to a high level of activity. At the 1989 SME-AIME Annual Meeting in Las Vegas, NV, the crushing and grinding session focused on wear materials in crushers and mills. Another session joined the process control group in its simulation-modeling and control of crushing and grinding circuits. Both sessions addressed the optimization in operating effectiveness. Specific subjects covered grinding media wear of forged and cast grinding balls and rubber lined mill liner wear. Also, the Semi Autogenous Grinding (SAG) Mill Conference in Vancouver in September 1989 provided a valuable update on the progress of SAG operations in recent years. Operationally, gold grinding and roasting circuits were implemented in 1989. Freeport McMoRan Gold started up two operations in Nevada. Two other circuits, both using SAG mills, are scheduled to start in 1990. These will be in Nevada and British Columbia. Elsewhere in gold, additional capacity continues to be brought onstream, both domestically and worldwide. In copper, expansions continue to call on additional crushing and grinding units. The unrest at Bougainville in Papua New Guinea has fueled a continued, strong demand for comminution in the copper sector. Specific equipment installed or started in 1989 included the ac variable frequency drive SAG mills in Australia, Alaska, and Papua New Guinea. Also, the gearless drive SAG mill in Chile provides tremendous flexibility in terms of mill speed. The trend toward moveable in-pit crushers continues -even at established operations.

Jan 1, 1990

By X. Meng

A kinetic model for batch leaching of various metals with different lixiviants has been developed. Overall material balances for reactants and products at the solid/liquid interface were formulated with various types of heterogeneous reactions in place at the interface. The solutions to these mass balances have been identified analytically as well as numerically using a Runge-Kutta method. Applications of these numerical solutions to various leaching systems using the rotating disc or powders have been discussed. Examples of the metal dissolution systems considered in this study include cobalt, nickel, copper and gold in acid, cyanide or ammoniacal solutions.

Jan 1, 1994

By C. R. Tinsley

Valuations can be molded, twisted and misinterpreted. Cases of spurious scope setting; limits to the information or access by the valuer; difficulties with the lack of comparative valuations; inappropriate valuation methods and outright speculations are described. None should be accepted by an experienced, independent minerals valuer. The Australasian Institute of Mining and Metallurgy (TheAusIMM) is working on a Valmin Code for which a Manual of Best Practice and Valuation Guidelines may be developed.

Jan 1, 1995

By B. A. Bancroft

A quality assurance program consists of all those activities aimed at providing confidence to the purchaser that the suppliers quality system will provide a product that will satisfy the purchaser's stated quality requirement. An organizing principle is necessary for prioritizing the quality control activities of quality personnel in the face of a myriad of technical possibilities, data-analytic applications, and an overwhelming number of possible activities promoted in the literature and by quality "gurus". The organizing principle I like is that quality assurance exists when those involved in the quality process: (1) know what they are supposed to do, (2) can tell if they are doing it and are set up to continue doing it and, (3) if they are not, they can remedy the situation in a timely fashion. Any incremental activity which facilitates this organizing principle is a continuous improvement activity. That activity which has the chance to facilitate this principle to the greatest extent is the next one to work on. In these days of lean corporate and regional staffs it is as important to know what not to work on as it is to know what to work on. In this paper I shall discuss in general terms the implications of this organizing principle for the design of Quality Assurance (QA) Programs for coal mines and also provide some comments about the application of Statistical Process Control (SPC) methodologies in the coal industry.

Jan 1, 1994

By Mona M. Fawzy, Ahmed A. Eliwa, Ebrahim A. Gawad, Ahmed H. Orabi, Amal E. Mubark

The growing demand for rare earth elements (REEs) has led to numerous recent studies to recover these elements from various bearing ores and wastes. Therefore, the recovery of REEs from Ras Baroud polymetallic concentrate has been investigated in the current study. Physical beneficiation for the Ras Baroud pegmatite sample was carried out, yielding a concentrate for euxenite (Y), fergusonite (Y), xenotime (Y), monazite (Ce), allanite, thorite, uranothorite and Hf-zircon, which resulted in raising the concentrations of REEs, Th, Zr, U and Ti in the sample. Fusion digestion processes with sodium hydroxide were studied using the conceived predictive diagonal (CPD) technique. The three experimental digestion groups proved the dissolution of 99.9, 95.6, 99.9, 52.5 and 0.47 percent for REEs, Th, U, Ti and Zr, respectively, under fusion conditions of 723 K, 120 min, 1/1.5 ore-to-alkali ratio, and smaller than 100-μm particle sizes. Fusion kinetics, isotherms and thermodynamics were investigated using several suggested models, namely, pseudo reversible first order, uptake general model and shrinking core model, which matched well with the experimental digestion results. Selective recovery of actinide content from the REE content of the digested concentrate chloride solutions was accomplished using solvent extraction with di-2-ethyl hexyl phosphoric acid. About 99.9, 99.9 and 4.2 percent extraction efficiencies for Th, U and REEs were realized, respectively, using 0.3 mol/L solvent concentration in kerosene as a diluent, 1/2 organic-to-aqueous ratio, aqueous pH of 0.2 and contact time of 15 min. Thorium and uranium ions were stripped with 2.5 mol/L sulfuric acid solution with 94 and 98 percent stripping efficiency, respectively. A highly purified REE precipitate was obtained from the raffinate solutions. Zircon mineralization tailings were obtained as a byproduct through the alkaline digestion process.

Oct 1, 2024

By R. E. Gertsch

A mobile-modular carbon adsorption mill design and operation for small to medium sized heap leach precious metal mines is presented. In the mobile-modular strategy, charcoal columns with adsorbed metal move from small strategically located carbon adsorption loading stations to a central stripping facility and back. The design has many advantages: 1) It scales-up from pilot plant to full production. 2) It has low capital requirements. 3) Operational costs are competitive with other systems. 4) Mill production can react quickly to changes in ore grade or property area. 5) The solution circuits are simple and easy to maintain. 6) Charcoal damage is reduced.

Jan 1, 1993

By Randhir S. Sehgal

After some decades of lying low and being treated as a second rate fuel, coal is back in the news. Production is rising. Predictions are for an ever expanding use, and they differ only in their rates of increase. Even the FBI is involved in trying to stop fraudulent sales of non-existent coal lands and leases to the innocent. In short, we have a nearly chaotic boom on our hands. Obviously our energy production base is in the process of undergoing a major shift, and the process will present many problems. However, there is little doubt that the industry has the basic strength and organization to be able to deal with the new issues that will arise as a result of these shifts in production and use of coal. After all, it does produce nearly 800 M tpy now, and coal is the single biggest fuel for generation of electricity. This role of coal is illustrated in the table below, which shows the coal equivalent quantities of various fuels used in the production of electricity.

Jan 1, 1980

By W. C. Morgan

Recently passed federal strip mining legislation officially emphasizes that the increased coal production required by this country through surface mining is going to be obtained only with stricter environmental standards. Dozing overburden down the hillside in Appalachian contour mining or leaving drag1ine spoils in area mining is now taboo and it is now or will soon be necessary to return the disturbed land to as good or better condition than before mining. These new restrictions will create a need for new and better ways to do the job. This paper describes one approach for utilizing scrapers and dozers to strip all of the overburden and to replace that overburden in an environmentally satisfactory fashion. The objective was to do this at a lower cost than that possible with the traditional dragline system using dozers and scrapers for reclamation and topsoil handling. In area stripping, the dragline has been able to move overburden at an extremely low cost. Operating costs of 8-13¢/bcy are typical in many operations where rehandling is not required. However, the cost of leveling the spoil piles and rehandling topsoil add considerably to the low basic cost of drag1ine stripping.

Jan 1, 1977

By Harold D. Palmer

The marine geologist and coastal engineer have at their disposal a wide variety of geophysical tools with which to investi¬gate sea floor topography and structure. Such devices include towed magnetometers, shipboard gravimeters and a variety of acoustical systems for recording the relief of the sea floor and buried structural features. The versatility of this latter group of systems lends itself to a variety of applications essential to those projects where excava¬tion of the sea floor is required. This paper describes the use of several acoustic devices and their Limitations and presents a case history in which a rapid survey from a small vessel provided detailed information critical to the planning stage of a specific coastal project. In this discussion, shallow water is defined as depths less than 150 feet. At present, this limit includes the maximum depth of economic dredging and most other offshore activities. To be sure, the maximum depth at which routine useful work can be accomplished is rapidly increasing, but the majority of current marine activities are located in water depths here defined as shallow.

Jan 1, 1968

By K. R. Miller

In recent years, surface mine equipment operators in the Campbell County region of the Wyoming Powder River Basin have found new ways to solve old problems. This paper will examine overburden stripping equipment and techniques by focusing on evolving applications for draglines, shovels, and dozers.

Jan 1, 1998

By Ernest B. Snyder

The word "line" has been used loosely for many forms of the common steel plant flux. For example, many people use the word "lime" for nigh calcium and dolomitic limestone, for high calcium and dolomitic quicklime (also called caustic lime, calcined lime; burnt lime, pulverized and pebble lime) and ;van for clinkered dolomite. Calcium hydroxide, also called slaked lime and hydrated lime, is called "lime" but is seldom used as a flux except when the quicklime air slakes in open boxes or bins. All of the above forms of "lime" are used in the steel plant. Calcium hydroxide is used for water treatment, acid neutralizing, and as a lubricant for wire drawing. All the other limes are used as fluxes in the sintering plant, blast furnace or steel producing furnaces. In the production of self-flux or super-flux sinter, high calcium and dolomitic limestone fines are used. Where quicklime fines are available, they may be added to the sinter mix also. The blast furnace uses both high calcium and/or dolomitic limestone. A few trials have been made using iron oxide stabilized dolomitic lime in an attempt to reduce coke consumption and to increase the production rate. The trials were very successful but would' not be economical, except in periods of coke shortages, with resulting extremely high coke cost and exceptionally high hot metal demand.

Jan 1, 1979

By Delbert Hamilton, Christopher Snyder

In the last three years there have been four uncontrolled heating events in mines that have been attributed to the use of polyurethane foam as a void fill product. These heating events are due to the exothermic reaction that occurs during application of these polymeric products. These events led the Mine Safety and Health Administration to issue a safety alert on polyurethane products used in void filling and ground consolidation in mining, with the goal of educating the mining community about this potential hazard. This paper provides an overview of various types of polymeric products and best practices, the factors that contributed to the heating events, and case studies involving polymeric products.

Jun 25, 2024

By Richmond Bennett

Airborne geochemistry became a reality with the advent of a high-sensitivity airborne gamma ray spectrometer with large volume NaI (TI) crystal detectors. Small variations in the concentration of potassium (as K40), thorium (as T1208) and uranium (as B1214) along the flight lines can be determined by measuring the gamma radiation with a sensitive airborne spectrometer. Small volume crystal spectrometers are useful only for detection of major surface uranium (Bi214) variations, but the large crystal volume system is an airborne geochemical exploration method capable of locating hydrothermal mineral deposits. Radioactivity as a guide to ore has been discussed in the literature by Damon (1950), Gross (1952) and others. The theoretical basis is that potassium, thorium, and uranium are concentrated in late stage solutions during magmatic crystallization. Thorium and uranium are concentrated in late stage liquids because their large atomic radius and high ionic charge prevent them from entering into the crystal lattice of common rock-forming minerals (Rankama and Sahama, 1950). Potassium, which has a large ionic radius and small charge, also can be concentrated in the high water content late stage fluids (Heier and Adams, 1964). A large proportion of uranium and thorium in rocks occurs around grain boundaries of the essential rock-forming minerals (Hurley, 1950). Uranium and thorium substitute for zirconium in zircon, a comparatively early forming mineral. However, most of the thorium and uranium is concentrated in residuals where they can be fractionated and incorporated into allanite, monazite, xenotime, and other minerals.

Jan 1, 1970

By Yixian Zhao

Although many ultimate pit limit design algorithms have been developed for the past one- quarter century, only the well known Lerchs-Grossmann's (LG) algorithm is capable of producing a truly optimum ultimate pit limit today. This paper presents a graph theory oriented algorithm for optimum ultimate pit limit design. This algorithm produces a true optimal solution and maximizes the total undiscounted net profit for a given 3-D block mine model. The algorithm performs much better than the well known LG algorithm, in terms of the reduction in computation time and computer memory requirements. More importantly the new algorithm is easier to understand and implement than the LG algorithm. Specifically, this paper discusses: 1) the computer representation of arcs and the rules of arc generations which dictate the formation of trees in the graph, 2) the mechanism of joint support and re-allocation, 3) the properties, the general procedures of the algorithm, and the suggested specific steps to implement the algorithm, 4) comparison between the new algorithm with LG algorithm, and 5) some experience in implementation of the algorithm and two case study results.

Jan 1, 1992

By J. B. Gwiazda

Maintenance of a constant load setting throughout longwall support units and selection of the proper initial bearing capacity depending on the type of roof strata are the basic factors that ensure good performance of roof support in a longwall. These requirements can only be met by hydraulic support. The greatest advantage of hydraulic support is achieved when uniform pressure is imposed on the roof throughout the length of the longwall. Such support, however, is provided only if each of the support units acts with the same force against the roof, i.e., has the same setting load. In such cases, the roof behaves like a uniform plate without bending and shearing stresses, thereby ensuring an undisturbed structure. Without a positive set value system, achieving an equal setting load for all units of the longwall support is impossible. Due to alterations of the feed line pressure of support units as well as some reasons related to man's psychology, operators extend the height at different setting loads. This produces nonuniform roof stress, and disturbs the structure. Consequently, the roof usually cracks. The author has developed a positive set value system, which is described in this Technical Note. Selection of the setting load Two pressure values in the feed lines are usually applied in longwall hydraulic systems. Lightweight support is fed by 25 MPa (250 bar) liquid, while heavy duty units receive a nominal pressure of 31.5 MPa (315 bar). Such pressure is required not only for the props but also to power the adjust¬ment jacks and the advancing ram. If the feed pressure is too low, there will be difficulty in shifting the unit despite the inversion system of the advancing rams. On the other hand, for many roof types, the feed pressure often appears to be too high when applied as the setting load pressure. An excessive setting load acts too strongly against the roof, crushing weak strata close to the roof. The author has recognized a case where an excessive setting load destroyed not only the nearby roof strata but also the strata above a 2-m (6.6-ft) sandstone layer. In addition, an excessive setting load relieves the side¬walls, increasing the resistance when using cutting machines. As a result, the yield of coarse coal is diminished, and increased fines dominate in the final product, lowering its economic value. As indicated, selection of the proper setting load, depend¬ing on the mining and geological conditions of the extracted seam, is extremely important. In some mines, measures applied to prevent disturbances include reduction of the feed line pressure by adjusting the feed pump valve. The disadvantage accompanying reduced feed line pressure is more difficult operation in advancing the ram. Due to the reduced feed line pressure, the force of the advancing ram is much lower than the designed value. Other designs suggest using a third feed line. However, installation of supplementary valves on the support units is required, a time-consuming and expensive procedure. The disadvantages of the powered supports are eliminated by a system designed by the author. So far, such a method of setting load control has not been used in any type of support. Setting load control unit The designed positive valve set for prop loading and the setting load control correspond to existing control systems for hydraulic powered support. The layout of the unit connected to the hydraulic prop control is presented in Fig. 1. The unit is marked LIDS. It incorporates three valves that may operate separately or connected. Valve A automatically opens and closes with liquid flow in the prop feed circuit. The valve is opened when the canopy touches the roof and closed when the support unit is withdrawn. Valve B serves as the setting load control. Valve C automatically opens and closes the flow in the line connecting the under-piston space of E to the prop F with the separator G. The valve block of each support prop is marked BZ. The UDS unit is connected by the hydraulic lines to the F prop control circuit. A valve is connected by H to pressure line J and by K to the G separator. In the UDS-3 version, line L is connected to M, linking the over-piston space of F prop with the G separator. Valve B is linked with valve A by a connector; it is also connected to the under-piston space E of prop F by line P. Valve C is fixed between lines K and P, connecting space E of prop F with the separator G. When setting the support, the liquid flows from line J through separator G, the BZ valve, and valve C to the space E of prop F. When reaching the roof with the canopy, valve A is opened and C closes. In this way it is impossible for the operator to cause the liquid pressure in space E of prop F to reach the level of line J. The prop pressure is set by valve B of the UDS unit. When withdrawing the support, valve C is automatically opened and A closed. Three UDS units have been fabricated and are designated

Jan 1, 1990