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By W. J. Birch, D. Leckenby, R. Farnfield

The use of electronic detonators to improve fragmentation is becoming universally accepted. However their use in limiting peak particle vibrations levels is still in its infancy. Most of which is anecdotal, in that few actual scientific studies have been carried and published. This paper details the research work carried out at a limestone quarry in the County of North Yorkshire in Northern England. Here a series of blasts were carried out some used non-electric detonators whilst others used electronic detonators. The majority of blasts were carried out at the same burden, spacing and deck charge weight loadings. Initially, the key variable was the difference in detonator type and then leading on to using the electronic detonators at specific exact different detonator timing intervals. Later the study was extended to include double row as well as single row blasts.

Jan 1, 2007

By Å. Kruukka, H. F. Broicher

The iron ores of the Kiruna mine in Sweden are of exceptional quality except for the phosphorus content in certain zones of the orebody. The prevention of mixing ores high in phosphorus with those low in phosphorus has always been of significant economic importance. The ongoing introduction of tele-mining and automatic haulage by LHDs requires new means in the field of quality control underground, as the experienced miner as well as the underground laboratory assistant no longer are involved in the process. As of 1998, LKAB has been testing prototypes of LIF (laser-induced fluorescence) analyzers for non-contact and real-time measurement of the phosphorus content of ore being transported by LHDs from the stopes to the respective ore pass assigned to a certain ore quality. The principles of the analysis of laser-induced fluorescence, the different test phases and results are described and conclusions made. With bulk sorting of ore underground, the mining engineer supports the efforts of the metallurgist in the processing plant.

Jan 1, 2002

By J. Koster

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Jan 1, 1939

By Christopher Mark, Gregory M. Molinda, Timothy M. Barton

The Coal Mine Roof Rating (CMRR) was first presented at this Conference nine years ago. Since its introduction, the CMRR has been incorporated into many aspects of mine planning, including longwall pillar design, roof support selection, feasibility studies, and extended cut evaluation. It has also become truly international, with involvement in mine designs and funded research projects in South Africa, Canada, and Australia. The purpose of this paper is to bring the mining community up to date with recent improvements and applications of the CMRR. The most important new development is a streamlined process for determining the CMRR from exploratory drill core. Just three types of information are now required: •Fracture spacing (or RQD) •Uniaxial compressive strength (or axial Point Load Testing) •Diametral Point Load Testing The moisture sensitivity adjustment has also been changed, and new research has related the immersion test to slake durability. Most recently, the CMRR has been implemented in a computer program, which can be obtained from NIOSH free of charge. The program facilitates calculation of the CMRR from either underground or drill core data. Values from many locations can be saved in a single file, and an interface with Autocad allows CMRR contour plots to be integrated into mine planning.

By Guy Chevalier

The QCM Mount-Wright mine and concentrator complex produces about 14 M tonnes of iron concentrate annually. Approximately 9.5 M tonnes of this concentrate are used to produce iron ore pellets at four different silica grades: Three for blast furnace operations and one for direct reduction furnaces. The paper presents the scientific approach that led to the realization of two projects where the acquisition of new process equipment led to an improved pellet plant iron recovery, a better flexibility and to lower operating costs as well as to the production of fine iron ore concentrate from the Port-Cartier tailings pond. Typical 4.8 % SiO2 concentrate is processed to achieve required pellet silica content. This is obtained with the aid of hindered settlers or hydraulic classifiers, screens, whims and, lately, spirals. The increasing demand for low silica iron ore products resulted in a greater need for upgrading. The Pellet Plant upgrading capacity being limited, more and more iron units were lost. Base on test works results and economic evaluations, QCM engineers figured out a way to increase efficiently their upgrading plant capacity and go back in the pond gather what has been lost in recent years of operation.

May 1, 2007

By Steve Dubnewych, Jon Kaneshiro, Calvin Jin

The Joint Water Pollution Control Plant (JWPCP), operated by the Sanitation Districts of Los Angeles County (the Districts), treats wastewater generated by over3 million people and processes wastewater solids generated by over 5 million people. The JWPCP Tunnel and Ocean Outfall Project, if constructed, would be one of the major marine outfall projects in the world. The new tunnel and ocean outfall system would provide relief to the existing outfall and allow inspection, maintenance, and repair of the existing tunnel and outfall system, portions of which were constructed as early as the 1930s. Geologic conditions are challenging along the alignments within the study are a being considered. Conditions include saturated alluvial soils, weak sedimentary rock, mixed face conditions, and squeezing ground conditions. Other significant challenges include the potentials for encountering up to 11 bars of water pressure, crossing seismically active faults, and encountering gassy and contaminated ground conditions. This paper discusses the details of the proposed project and the associated challenges.

Jan 1, 2007

By Kurt Meyer

La geotectónica es la ciencia que trata de la estructura de la corteza terrestre y de los procesos y fuerzas que han contribuido a su formación. Sin embargo, todas las relaciones tectónicas son situaciones confirmadas en el espacio sometido a las leyes física. En este sentido, el proceso tectónico está constituído esencialmente por deformaciones, acumulaciones de masas de piedras y por desarrollo en el tiempo. Por consiguiente, el presente texto describe dos grandes ciclos de problemas y las tareas que se producen en sus relaciones recíprocas y divisiones ulteriores. Así, tenemos el ciclo geotectónico (geosinclinales, continentes, océanos) y el ciclo geomagmático. De otro lado, se describe las fases del plegado y los períodos de la geología geotectónica.

Jan 1, 1968

By T. R. Ellis

Minerals Appraisers/Valuers often find great difficulty or failure in attempting to employ the Sales Comparison Approach to the Market Value Appraisal of development and operating stage mineral properties. An important factor generally overlooked is a comparison of net operating income (NOI) margins on a per-unit-of-production basis between mineral properties, whether these be demonstrated or forecast margins. NOI margins can vary greatly between mines or quarries that are producing similar products. Ultimately, the expected NOI margin determines what a buyer is willing to pay for an income producing property. Common criticisms of the sales comparison approach by minerals appraisers are introduced. These are counterbalanced by raising some issues in the way the inputs for the Income Approach are usually derived by minerals appraisers, and by review of some conspicuous examples of the much too common misuse or abuse of the income approach in market value minerals appraisals. Example transaction analyses and sales comparison analyses are used to demonstrate the author?s methodology for adjusting units of resource in his transaction adjustment tables (see APPENDIX). The examples are used as the basis for discussion of ways to employ adjustments for operating economics and many other factors, while cautioning about the potential for double counting. The conclusions include a recommendation that minerals appraisers attempt to apply at least two of the three valuation approaches when appraising the market or fair value of development and operating stage mineral properties, the two being the sales comparison and income approaches.

Jan 1, 2011

The MineSight Schedule Optimizer (MSSO) is a new production scheduling tool developed by Mintec, Inc. using mixed integer linear programming (MILP) techniques. This tool was developed to solve the short- and medium-term schedule problems for surface and underground mining operations that involve multiple mining areas, multiple processes, multiple destinations and blending requirements. MSSO finds the optimum schedule in each period that achieves the objective while satisfying comprehensive product quality and quantity requirements as well as physical and technical constraints. Using the MineSight Planning Database (MSPD) as a central data hub, MSSO seamlessly works with MineSight 3-D (MS3D) block models and third-party data, MineSight Interactive Planner (MSIP), MineSight Haulage (MSHaulage) and MineSight Activity Planner (MSAP) to prepare data, formulate MILP models, calculate, report, fine-tune, save and visualize schedules. This paper presents the features and capabilities of MSSO. A case study is also given to demonstrate the applications of this new tool.

Jan 1, 2009

By A. Soderberg

This paper describing the mining practice at the Utah Copper Co., Bingham Canyon, Utah, is one of a series being prepared by the Bureau of Mines on mining practices, methods, and costs in the various mining districts of the United States. The Utah Copper Co. operates the low-grade open-out copper mine at Bingham Canyon, Utah, which is 30 miles in a southwesterly direction from Salt Lake City. In addition to the mine the company operates two flotation concentrators, the Magma plant and the Arthur plant, which have a combined capacity at maximum metallurgical efficiency of 60,000 tons daily. The concentrators are at Magna, about 18 miles from the mine. The company operates its own standard-gage railway, known as the Bingham and Garfield Railway, between the mine and the mills (fig. 1). Concentrates are smelted at the Garfield smelter of the American Smelting and Refining Co., situated 4 miles from the mills.

Jan 1, 1930

By Rick Frechette, Bryan Ulrich

Representatives from several mining operations in three western states left their mines behind for a day in February to discuss with their peers the issue of water. The event was Knight Piésold and Co.’s Roundtable 2007, held in Elko, NV. It was third such event put on by the company. The issue this year was site-wide water considerations.

Jan 1, 2007

By M. G. Driessen, H. E. Criner

Possible applications of cyclone thickeners for: (1) clarification of the washery water and, (2) recovery of fine coal from the plant bleed. The paper shows: (1) that it is possible to remove all particles including the very finest, from the circulating water, thus obtaining a closed water system and, (2) that reduction of the ash content of the solids of the plant bleed is feasible by means of cyclone thickeners. Performance data for different size cyclones is given in the form of graphs.

Jan 1, 1950

By R. A. Meyr, K. A. Perry

Following three major mining accidents in 2006, the MINER Act of 2006 was enacted by the U.S.Congress. The U.S. Mining Safety and Health Administration subsequently released the Final Rule on Refuge Alternatives for Underground Coal Mines, which required every underground coal mine to install refuge alternatives to help prevent future fatalities of trapped miners in the event of a disaster. The following paper documents the research that was performed on a structural wall to be used in conjunction with a breathable air system to create a refuge alternative. A 103.4-kPa (15-psi) safe haven polycarbonate wall for use in underground coal mines was designed and modeled using finite element modeling in ANSYS Explicit Dynamics. The successful safe haven wall design was modeled for an actual underground coal mine environment using the explicit finite difference formulation program FLAC3D to determine the responses of the wall and surrounding strata within a mine. A full-scale design was fabricated and installed in an underground coal mine to determine any construction constraints and as a final step in proof of concept for the safe haven wall design. This paper is meant to introduce the reader to a new wall concept to be used in conjunction with current technology.

Jan 1, 2013

By R. Oler

The need for yieldable ground support, particularly in high stress or deep mining conditions, has grown in recent years. This paper highlights some of the current industry limitations and provides selection criteria for a new yielding ground support system, DSI?s Dynatork Bolt. This bolt distinguishes itself by withstanding 16 ? 30 kJ of energy deflecting loads anywhere from 7 ? 20 tons (depending on the energy). A summary of the laboratory test results and case studies will also be presented as a measure of the performance of this dynamic product.

Jan 1, 2012

By J. Bakken, M. Th. Jonsson, G. Sævarsdottir

A typical three-phase submerged-arc furnace for production of silicon metal and ferrosilicon has arc currents ~100 kA, phase voltages ~100 V and total furnace power ~10 - 60 MW. The arcs burn in gas filled cavities or "craters", where the main atomic components of the plasma mixture are silicon, oxygen and carbon. Two quite different simulation models for high-current AC arcs have been developed: the simple Channel Arc Model (CAM), and the more sophisticated Magneto-Fluid-Dynamic Model (MFD). These models have been described extensively and results reported at INFACON-8 and INFACON-9, respectively. The coupling between the arcs and the AC power source is described by a complete three-phase Electric Circuit Model. Recent numerical modelling studies of industrial AC arcs show that the boundary conditions at the cathode and anode are critical for the simulation results. A novel Cathode/Anode Sub-Model for high-current AC arcs that treats both cathode and anode indicates a completely different cathode behaviour than previously assumed. A cathode spot which serves a high-current electric arc is shown to be dominated by the energy impact from the arc. This leads to lower cathode fall voltage than obtained from previously developed models. The anode fall voltage is negative, as the main function of the potential barrier is to repel plasma electrons. The cathode spot is diffuse in the sense that the arc in fact contracts away from the cathode. Simulation results are compared to measurements on both industrial furnaces and smaller scale pilot furnaces. An important conclusion, supported by our arc studies, is that the arc length in silicon metal and ferrosilicon furnaces does not exceed 15 cm and the arc may burn anywhere on the electrode, not necessarily beneath the electrode tip.

Jan 1, 2004

By Virginia T. McLemore

The Gallinas Mountains are in northern Lincoln County and southern Torrance County, New Mexico, USA where a series of alkaline igneous bodies, including porphyritic latite, trachyte/syenite, andesite, and rhyolite laccoliths, flows, dikes, and plugs, have intruded Permian sedimentary rocks belonging to the Permian Abo, Yeso, and Glorieta Formations. A small amount of bastnaesite, a REE mineral, was recovered during processing for fluorite from the Gallinas Mountains. Four types of deposits are found in the Gallinas Mountains: epithermal REE-F veins, Cu-REE-F veins, REE-F breccia pipes and iron skarn deposits; all are associated with Tertiary alkaline to alkalic-calcic igneous rocks. Alteration includes brecciation, silicification, chloritization, and fenitization. District zonation is defined by Cu-REE-F (±Pb, Zn, Ag) veins that form center of the district, surrounded by REE-F veins. Carbonatites are inferred at depth by the presence of fenitization, carbonatization of the breccias, presence of REE and similarity of the intrusive rocks and mineralization to areas with known carbonatites.

May 1, 2011

By G. Donald Emigh

WESTERN phosphate resources which lie in Ida- ho, Montana, Utah, and Wyoming, have seen great expansion of activity in recent years. Growth has been two-pronged: expansion in fertilizer use, and since 1949, into the elemental phosphorous industry. Elemental phosphorous, produced in the electric furnace, goes largely into chemical making. Phosphate ore was first recognized in the West about 1889. Production started in 1906, and for many years consisted of underground operations by small companies operating sporadically. In 1920 Anaconda Copper Mining Co. opened the underground Conda mine near Soda Springs in southeastern Idaho, and has maintained and increased its operations since then. About 1930 Montana Phosphate Products Co. began underground mining in Montana and has remained a steady producer. In 1945 San Francisco Chemical Co., one of the oldest companies in the western field, initiated strip mining at the Waterloo mine near Montpelier, Idaho, and later at Leefe mine near Sage Junction, Wyo. In1946 J. R. Simplot Co. began open pit mining at Gay mine near Fort Hall, Idaho. In 1950 Victor Chemical Works began underground development work in the area of Maiden Rock, south of Butte, Mont.: and has since mined there. Monsanto Chemical Co. began open pit mining near Soda Springs, Idaho, in 1951.

Jan 11, 1954

By O. Ditsele

Coal plays an important role in the energy needs of the World. Given its wide abundance and low cost, coal use is bound to increase with the growing energy demand. Despite its importance, there are growing concerns over coal?s environmental burdens, especially its contribution to greenhouse gas emissions. To ensure sustainable extraction and use of coal, opportunities for minimizing potential impacts from coal have to be identified and exploited. Whilst extensive work has been done on life cycle assessment of coal use, especially in electricity generation which uses the bulk of coal produced, there has been limited work focusing specifically on coal mining. This study aims to estimate the cradle-to-gate life cycle climate change impacts of coal from a surface coal mine in the United States. The study employs general principles of ISO standards for LCA.

Jan 1, 2010

Let’s start off with your assessment of the mining industry. Today, the status of the mining industry is stronger than it has been over the previous few years. While mining continues to be a major part of the world’s economic foundation, the industry is gaining strength due to rebounding metals and minerals prices. And now, with these rising prices and the changes the industry instituted during the years when mining-related commodities were selling at low prices, our stronger, more productive and internationally competitive industry should flourish. Mining remains an essential business and the industry is far ahead of the game when it comes to the trend of globalization as a key to sustained growth. Also, the industry continues to realize increased productivity through technological innovations. And an increasing number of countries are moving towards capitalism, which opens doors for exploration and mining within their borders. After looking at all of these factors, I believe that the mining industry will only continue to gain momentum in the future.

Jan 1, 2004

By W. H. Oppelt

To provide a relatively structurally stable form of dried lump lignite, two North Dakota lignites from Mercer County were dried by the Fleissner process in an atmosphere of saturated steam at 200, 300, and 370 p.s.i.a. pressure, corresponding to steam temperatures of 382°, 417°, and 437° F., respectively. Two series of experiments were made at each test pressure with the individual lignites. In one series, the autoclave was preheated to the processing temperature before charging the lignite; in the other the lignite was charged into the autoclave at room temperature. In each case, heat losses were determined by blank tests of steam consumption over a similar operating cycle with the empty autoclave. The degree of moisture removal and net steam consumption were calculated from material balances. The amount of water removed as a liquid from the two North Dakota lignites during the heating and steaming periods was compared with results calculated from previously published data on drying Austrian lignite and Australian brown coal. These lignites, covering a wide geographical area, had original moisture contents ranging from 35 to 49 percent. The Austrian lignite and Australian brown coal are considered to be of Miocene Age, and the Dakota lignites belong to the Paleocene.

Jan 1, 1955