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By Dragomir Gospodinov, Savka Dineva

A surprisingly large mining-induced seismic event occurred in the LKAB Kiirunavaara Mine (Sweden) on 18 May, 2020 at 03:11 (local time). The estimated moment magnitude was 4.2. The event caused extensive damage in a large section of the mine. The production in the area is not yet resumed, even by the beginning of 2022 (~20 months after the event). The Kiirunavaara Mine has one of the world’s largest underground seismic systems with approximately 253 geophones. The in-mine records of the event showed a very complex character with a several sub-events. The event was also well recorded by seismic stations out to over 9,000 km distance. Data from the underground and regional seismic systems were analysed to define and compare basic source parameters such as hypocenter location, seismic moment, as well as the seismic moment tensor. The data from the in-mine seismic system was used to study the development of the seismic process and to define elementary seismic sub-sources together with the official hypocenter location.

Apr 26, 2022

By Ali Sogue, Steven Schurman, R. Jensen

This paper presents the results of the remediation of the Gregory Gulch #1 Superfund site, an EPA Clear Creek Superfund project located in central Colorado. The Gregory Gulch #1 site was an historic gold mine and mill located within the city limits of Central City, Colorado. Remediation efforts included the use of the Envirobond™ additive to chemically bind the metals in 3,000 tons of acid generating mine waste that contained high levels of arsenic, lead, zinc and mercury. The toxicity of the mine waste amended with Envirobond™ was not only reduced to RCRA TCLP standards but also to the more stringent UTS standards. The final cost of the treatment was much less than standard industry solidification processes and significantly less than offsite disposal options.

Jan 1, 1999

By Valeh Aghazadeh, Shima Barakan, Mina Soleymani, Ehsan Bidari, Morovvat Faridazad

Molybdenite is the most important molybdenum concentrate, which is mainly recovered as a by-product from porphyry copper deposits. Due to the low efficiency of purification processes such as flotation in the reduction of copper content of molybdenum concentrate to a standard level (i.e., less than 0.5 wt.%), further purification by a hydrometallurgical method is required. Although different types of chemical reagents were found to be effective in the leaching of copper minerals from molybdenum concentrate, the mechanisms of these processes remain largely unexplored. In this study, optimal conditions for maximum copper leaching (> 99%) were obtained at the concentration of HCl = 1 M, FeCl3 = 0.5 M, CuCl2 = 0.05 M, CaCl2 = 0.5 M at 75 °C, 500 rpm, and S:L = 1:10 during 60 min. CuCl2 was identified as the most effective leaching reagent for copper dissolution in agreement with Visual MINTEQ model results due to the formation of various types of copper chloride complexes. Furthermore, the electrochemical behaviors of FeCl3, CuCl2, and CaCl2 reagents before and after the leaching process were investigated by the cyclic voltammetry technique. The results of cyclic voltammograms at different scan rates verified the presence of copper chloride complexes, and ferric ions as the oxidizing reagents for better dissolution of copper sulfides. Based on kinetic study results of shrinking core models, both chemical and diffusion reactions controlled the copper leaching process with an obtained activation energy of 33.56 kJ/mol. For recovery of the leached copper, the precipitation process was done by the addition of Na2S at 45 °C, S/Cu = 1, and pH = 9.

Dec 26, 2022

By Graham J. Morgan

The following material is excerpted from a presentation Mr. Morgan gave recently to representatives of the financial community. Introduction 1982 was a period of challenge for United States Gypsum Company because of reduced market opportunity. Housing starts for the first 10 months averaged a seasonally adjusted annual rate of 1 million units, 9% below the comparable 1981 period when housing starts were the lowest in 35 years. Industry gypsum board shipments declined 9% from the already low levels of the same period in 1981. US Gypsum met the challenge with stringent cost reduction programs and aggressive action in the marketplace. In late 1981, anticipating market deterioration, the company's management adopted strategies to focus on two shortterm objectives: • Adjust operations to perform profitably in view of limited opportunities through more efficient operations and asset management. • Continue to strengthen U.S.G.'s resources and ability to take advantage of important market opportunities as the economy improves through selective expansion of production capacity in key growth markets. Concentration on these two objectives resulted in a nine month performance in 1982 that, while certainly not satisfactory by company standards, compared very favorably with that of principal competitors in terms of net earnings, margin on sales, and return on average stockholders' equity. To counteract limited market opportunities, U.S.G. focused on productivity improvement, cost reduction, expense control, and maximization of market penetration. Energy Use Improving performance encompassed all segments of operations. For example, efficient use of energy was a significant factor despite lower operating rates at most plants. Overall, in the third quarter of 1982 versus 1972, the company used 27% less energy per unit of production, a savings of $15 million in that quarter alone. These continuing improvements helped to partially offset constantly rising energy costs. A number of operations achieved superior results in the first nine months of the year compared with the same period in 1981. For example, gypsum board plants in Jacksonville, FL, and Sweetwater, TX, recorded 8% and 7% reductions, respectively, in energy use per unit of production. Paper mills in Oakfield, NY, Galena Park, TX, and Kansas City, MO, each reduced energy use more than 12%, while the Greenville, MS, ceiling products facility achieved a 16%o reduction. Safety Safety is another important element that received increased attention. U.S.G.'s safety performance over the past five years has consistently improved. In 1981 it was five times better than that of the gypsum industry; nearly 10 times better than all industry as measured by the National Safety Council; and almost 20 times better than all US manufacturing as recorded by the Bureau of Labor Statistics. In addition to human concerns, this excellent record results in significant dollar savings that directly affect company results. In 1981, U.S.G.'s pre-tax savings in claims, premiums, and related expenses were about $20 million compared to the industries in which it competes. For the first half of 1982 performance improved further, with a cumulative lost workday incidence rate per 200,000 man-hours worked of only 0.27, an all-time record. Expense Control Careful control of inventories and receivables also received special attention. As of Sept. 30, 1982, inventories were 29%, or $44 million, below the level of Sept. 30,

Jan 2, 1983

By Charles T. Staniek

Following a dragline relocation at Agrico's Fort Green phosphate mine in 1986, the recovery plant experienced a significant decrease in flotation performance. Through weeks of trial and error testing, we discovered we could restore recoveries by conditioning feed at pH's higher than we had used historically. The higher pH's essentially increased flotation cell kinetics, although we still do not understand the exact mechanism at work. Armed with new-found appreciation of pH modification, we initiated a program to determine the optimum modifier for us, from both a performance and environmental perspective. Environmental considerations were important because ammonia, the standard industry modifier, is a plant nutrient and higher usage rates could affect the quality, of our recycle process water. This paper describes the research and development work spanning a 3 year period that culminated in making a major change in our reagent suite when we replaced ammonia with soda ash on a permanent full-time basis.

Jan 1, 1993

By C. A. Rowland

When studying the feasibility of using autogenous or semi-autogenous grinding, operating and engineering companies frequently request assistance from the mill manufacturers in three areas - 1. Recommendations for studying the suitability of autogenous or semi-autogenous grinding for the specific ore. 2. Mill sizing, to accomplish required grind. 3. Recommendations on mill design and operation. Rod mills and ball mills are selected by the use of bench scale standard grindability tests and established calculation procedures, of which the most frequently used are the Bond Grindability tests and the Bond Work Index equation(1). The accuracy of these have been reviewed by C. A. Rowland in his papers, showing the correlation of work indices calculated from plant operating data and laboratory grindability tests(2)(3). The selection of autogenous and semi-autogenous primary mills has not reached the stage where mill size selection can be made from bench scale tests. Considerably more extensive testing will be necessary than required for selecting rod mills and ball mills.

Jan 1, 1974

By August E. Vandale

I speak to you today on the subject assigned to me, "Subsidence - a Real or Imaginary Problem", as a representative of Consolidation Coal Company (a wholly owned subsidiary of Continental Oil Company). The information I relate to you is our experience in the Pittsburgh Coal Company Division of Consol and covers the Pennsylvania properties and mines with particular emphasis on the mines in the south- western portion of the State or in the immediate vicinity of Pittsburgh, Pa. Mining of Freeport and Pittsburgh seams of coal in the Pittsburgh vicinity dates back over one hundred years. Consol, or its predecessor, Pittsburgh Coal Company, has been actively engaged in mining in the area since Pittsburgh Coal Company was organized in 1900. Pittsburgh, Pennsylvania came into prominence as the Steel City largely because of the vast reserves of high grade metallurgical coal readily available in the immediate vicinity and also because of its favorable river transportation. Early in the 1900's we operated over 100 small coal mines, with operations located in the Counties of Allegheny, Fayette, Washington, Westmoreland. We have also operated mines in Somerset and Greene Counties. Titles in Pennsylvania can be in three estates: (1) title in fee, (2) title to the mineral, (3) mining rights permitting the removal and extraction of the mineral with or without waiver of surface damage. Consol has over the years acquired good legal title to the coal lands purchased from individual farm owners, with good broad mining rights, and in 98% or more of its title has a complete waiver of surface damage or the right to subside the surface land. In the early days of our Company, individual coal farms were purchased from land owners. Many of these titles severed the coal estate from the in fee title and good mining rights with waiver of surface were conveyed in the original severance deed. Thus, minable coal reserves were put together by the purchase of the coal under many individual farms in an area. In the early years, the mines practiced hand dug mining - later going to mechanical cutting with hand loading of the coal. Systems used were entry driving with room and rib panels. We have practiced full recovery mining as far as practical during the years of hand loading, as well as in the later years when the mines were mechanized. Mining system layouts, methods and procedures have changed from time to time to keep pace with improved mining machinery and new inovations, such as roof bolting and rubber tired haulage.

Jan 1, 1967

By C. Athanassopoulos

Geomembranes have been used in the mining industry since the early 1970s in solution and evaporation ponds, tailings impoundments, and heap leach pads. Traditionally, heap leach pad lining systems have consisted of a single geomembrane liner placed directly over a prepared subgrade of locally available soil. Heap fills are constructed by placing a layer of highly-permeable drainage stone (overliner) over the geomembrane. Crushed ore is then placed on the leach pad in 3- to 10-m (15- to 30-foot) thick lifts, sometimes reaching final heights of several hundred feet. The crushed ore is irrigated with a chemical solution which dissolves the precious metals from the ore. The nature of the chemical leaching solution depends on the metal being targeted. Low pH sulfuric acid solutions are generally used to leach copper and nickel; high pH cyanide solutions are used to leach gold and silver. The metal-laden pregnant leach solution (PLS) passes down through the ore pile and is captured in a drainage system. Metals are extracted from the leach solution and the solution is then recycled back onto the leach pile. When under load, geomembranes are vulnerable to damage from large stones both in the soil subgrade and in the overlying drainage layer. Although intact geomembranes are virtually impermeable, installed geomembranes will have a small number of holes due to imperfect seams or damage during construction and filling operations. These holes serve as open pathways for leakage into the soil below. Smith and Welkner (1995) estimated liner leakage rates ranging from 5 to 10,000 L/ha/day, depending on the type of heap pad liner and level of construction quality assurance (CQA). Thiel and Smith (2003) reported liner leakage rates up to 2,000 L/ha/day for a valley fill facility with heads ranging from 15 to 35 m.

Jan 1, 2011

By Z. Mullard

The introduction of social media platforms has ushered in a new era of interaction and information exchange, which impact business-to-society relationships. Mining companies are closely watching these platforms, as the industry takes a cautious approach to control flows of information. This paper explores the risks, challenges and opportunities of using social media, based on a qualitative mixed methods investigation with stakeholders from the Canadian mining industry. Generational and language barriers, misunderstanding and limited motivation from regulators make implementing social media platforms challenging and risky at an organizational level. The benefits of social media include being able to mobilize communities and share information in real time. Despite the challenges, the study found that 62% of mining stakeholders are incorporating social media tools, mostly in an ad hoc manner. Flexible strategies for transparent communication and public engagement are creating new opportunities for information exchange.

Jan 1, 2011

By Alan C. Richter

Introduction The East-West Gateway Coordinating Council is an organization of local governments formed in 1965 to identify regional problems and to formulate policies, plans and programs to resolve them. The major goal of the Gateway Council is to improve the quality of life for the citizens of the St. Louis Region. While East-West Gateway Coordinating Council is the organization I represent and it only deals with the St. Louis Metropolitan Area, you will find one or more similar organizations in each of our nation's urbanized areas. As a result, for illustrative purposes, I will use my organization to portray what is happening nationwide. For example, in order to eliminate duplication, the Council reviews local applications for approximately 100 federally funded programs in such areas as highways, mass transit, parks, water treatment, and sewers before they can be sent to the appropriate funding agency. The Council's varied functions place it in a unique position of receiving more and more responsibility for developing strategies of implementation of various environmental regulations. This is due to the fact that environmental control is a relatively new field and we, as a country, are relatively inexperienced. The resulting regulations and guidelines will depend, to a great extent, on what the general public is willing to accept in terms of controls and what price they are willing to pay in terms of taxes and increased costs. Land Use: Growth vs No Growth This is perhaps the most encompassing environmental issue. We, as a nation, are beginning to realize that land is a limited natural resource and that the way we choose to use 'this resource affects many other aspects of our lives--whether we can catch edible fish in the Mississippi, how much we pay for sewer services, if we can swim in a

Jan 1, 1977

By Kenneth W. Luke

In the development of the ultimate pit limits for a narrow ore body, pa¬rameters necessary in the design of a functional, or working, pit become highly sensitive factors in the determination of ore reserve levels and their associated waste to ore stripping ratios. Through the use of geologic cross sections, ore reserves can be roughly calculated by utilizing a straight line approximation for pit wall slopes. The optimum position of the pit floor can be substantially altered from such a preliminary design though with the introduction of functional mining parameters, such as a ramping network, and working bench heights, berm widths, and bench to bench wall angles. Originally a computer program was developed to quickly evaluate changes in cross-section pit design with minimal alteration of input data. After developing a satisfactory technique of cross-section evaluation which incorporates working mine parameters, an optimization algorithm, or procedure, was developed and included in the program to eliminate much of the tedious manual decision-making required in determining the optimum location of the pit floor on each cross section. Optimization in this case implies the maximum profit pit. When pit and processing costs are defined or hypothesized, this computer program can be used to design the maximum profit pit, constrained by the recognized functional mining parameters. A second way of stating the optimization is that the program can be used to develop a pit design which minimizes waste stripping at any desired ore reserve level. The basic method of cross-section evaluation parallels present manual methods. Program input is a combination of data obtained directly from cross sections developed for, geological interpretation and pit design parameters selected by the mine planner. As a result it is easy for the mine planner to comprehend what the program is accomplishing, and thus participate in the development of the computer assisted design.

Jan 1, 1971

During development mining, ventilation capacity may decrease and the ventilation requirements may depart from initially planned values depending on the mining rate, increases in the methane emission rate, and changes in ventilation airway leakages. Insufficient ventilation air quantities and the occurrences of high methane liberation rates can overwhelm the existing quantity of ventilation air and result in elevated levels of methane gas during development mining. This condition can both limit the development of that section and increase the risk for an ignition that may lead to an explosion. Thus, the prediction of ventilation air requirements prior to mining can enhance worker safety by reducing the likelihood that explosive methane-air mixtures form. This study presents an approach for prediction of methane inflow rates using coalbed methane reservoir modeling. For this purpose, a two-phase coalbed reservoir model of a three-entry type roadway is developed. In the model, grids are dynamically controlled to simulate development of entries. Examples are given for methane inflow and ventilation air requirements as a function of mining rate, development section length, mining height, and the existence of degasification boreholes. This technology can be used to limit the methane concentrations occurring as a result of the influences of various coalbed and operational parameters.

Jan 1, 2008

By FJ. Johnson

Polymer utilization has increased steadily over the past several decades; however, their usefulness is sometimes limited by natural forces. For example, polymers tend to degrade when subjected to elevated temperatures. This degradation can release toxic fumes, create excess smoke, and aid in the spread of fire. For these reasons, many polymers are filled with various compounds which impart flame retardancy (FR) properties. These fillers do not make polymers non-combustible; rather, they increase resistance to ignition and reduce bum rate. Also, they suppress smoke generation, which is important as up to 80% of fire-related deaths are due to smoke inhalation [1]. Therefore, methods to impart flame retardancy in polymers are industrially important. The early flame retardants used in polymers were halogen-based, working on the principle of inhibiting free radical formation in the vapour phase thus impeding combustion propagation [2]. Usually these were combined with antimony compounds such as Sb203 to decrease loading, yet provide the same FR qualities. However, questions have arisen recently concerning toxicity of halogenated flame retardants. Possible release of toxic compounds (such as dioxins) upon combustion has been reported [3]. Fear of future regulations concerning halogen addition has led to the search for different FR fillers. Two of the more common replacements for halogen-based systems are alumina trihydrate (Al(OH)3 or ATH), and magnesium hydroxide (Mg(OH)2)' These systems impart flame retardancy through heat absorption and by release of water of hydration upon their decomposition. ATH has a low decomposition temperature (230°C), limiting its use to unsaturated polymers, epoxies, urethanes, and some wire and cable formulations. However, some advantages of ATH over halogenated FR are that it is relatively cheap, doesn't generate toxic gases, is non-volatile, and is impervious to moisture [2].

Jan 1, 1997

By Pramod C. Thakur

During the past ten years, the US coal industry has experimented with various ways to extract methane from coal seams. Drilling long horizontal boreholes in solid coal from mine workings and vertical gob degas boreholes are becoming standard techniques for methane recovery from coal seams. Prime motivations for such work have always been safety and productivity in mines, but the commercial value of gas so produced is encouraging utilization. The paper reviews various ways to produce methane from coal seams and discusses some utilization projects extant in the industry.

Jan 1, 1984

By K. P. Pavlich

Strategic planning, including the process of developing competitive strategy, is an integral part of all organizational management; from one person operations to multi-national Fortune 100 firms. The structure of that process varies from decisions and direction based upon one person's intuition to the integration of multiple strategic planning groups from each of a firm's many business units. Everyone has heard interesting strategic planning stories such as the railroad industry's long term failure to realize that they were in the transportation business and not the railroad business, the decision to "give away the razors and sell them the blades", Caterpillar's "SOQ NaP" campaign (Sell On Quality, Not On Price), or the tanker industry's eventual realization that by better managing turn-around the firm could control their largest single cost: depreciation. It is important to remember that very few strategic planning decisions are going to become Harvard Business Review case studies. That fact does not, however, diminish the need for understanding the firm's business, and actively planning how it is going to remain in business in the future!

Jan 1, 1989

By G. A. Campbell

Mining companies have been very interested in the presence of a number of small but high-grade ore bodies of base metals in northern Wisconsin and the west/central section of the Upper Peninsula (UP) of Michigan. The region is rural with outdoor recreation/tourism and lumbering being the key industries. The economy of the region is based on the use of its natural resources, and mining is not a new activity to the region, especially the UP. The western UP was historically a key mining district for copper and iron, and today the central UP has a significant iron-mining district. However, all efforts to develop the base metal ore bodies have been met with a storm of controversy involving the local community, regional activists, Native Americans, and the state government, and only one mine has gone into operation. There is concern by some stakeholders about the sustainability of mining in communities that depend on the environment for tourism, recreation, and other commercial activities. There have been four attempts to get the necessary approvals to mine in this region: the successful Flambeau Mine effort (Wisconsin), the failed Crandon project (Wisconsin) and Lynne project (Wisconsin) efforts, and the continuing effort to get the Eagle Project (UP of Michigan) approved. The cases are presented to illustrate the project situation, the history of the permitting effort, and the opposing parties and their concerns. The case of the Eagle Project is looked at in detail by using the method of discourse communities and discourse analysis. Results of the analysis provide insight into the communication efforts to address community concerns about sustainability and what more can be done to improve this dialogue.

Jan 1, 2008

By Chuck R. McLendon

A new face ventilation system was needed at the Allied Chemical Trona mine, near Green River, Wyoming. The development of an exhaust manifold face ventilation system came from a need to reduce the dust and noise concentration level while maintaining methane control at the continuous miner working face. Dust laden air from a heading being driven by a continuous miner was contaminating the intake air in the mine around the roof bolter operator and adjacent headings. Each working heading was exhausted into the last open crosscut by a face fan. A face fan would contaminate the adjacent downstream heading with dust-laden air until a high dust concentration developed in the final entry before the returns. A face ventilation system was needed to give the exhaust of each heading an individual path to the return air. In addition, the system could not interfere with the present room and pillar mining process. A manifold system of rigid duct ventilation tubing was designed using the existing fans in a parallel arrangement. Each system was to consist of the rigid duct tubing in three headings junctioned together at the last open crosscut and exhausted at a common branch in the return air. Each heading was to have its own damper (or valve) so that air could be directed where it was most needed. The system was installed using both round and oval rigid duct ventilation tubing to minimize head loss and to allow proper ground clearance for mining machinery. Two fans in parallel were used to exhaust three headings. By adjusting the valves at each heading, up to 18.0 kcfm (9.36 cu m per sec) could be exhausted from one heading and still keep the methane level controlled in the other two headings. The manifold exhaust system has proven to be an efficient, long lasting ventilation system at the Alchem Mine. It has reduced the dust and noise exposure levels at the working faces while keeping the methane level under control.

Jan 1, 1980

By M. E. Kuchta

LKAB's Kiruna mine, located above the Arctic Circle in northern Sweden, is one of the world's largest underground mines, and it is one of the most modern. The Kiruna orebody is a high-grade magnetite containing about 80% low-phosphorous iron ore and about 20% high-phosphorous iron ore in situ. The mining method used is large-scale sublevel caving. Due to the blending of high-phosphorous ore with low-phosphorous ore during the extraction process, only about 20% of the run-of-mine ore can be used for the mine's low-phosphorous product. The blending process is highly irregular and difficult for the mine-planning personnel to predict. An algorithm was developed that uses principles of gravity flow to predict the run-of-mine phosphorous grades from the in situ geologic block model. The model can be used for both long- and short-term predictions.

Jan 1, 2003

By Ralph H. Knode, Stephen P. Collings

INTRODUCTION The Crow Butte uranium deposit is located in northwest Nebraska near the town of Crawford (Figure 1). The deposit was discovered during the fall of 1980 by Wyoming Fuel Company, operator of the Crow Butte Joint Venture. The Crow Butte Joint Venture is owned 50 percent by Wyoming Fuel Company, a subsidiary of KN Energy, Inc.; formerly Kansas-Nebraska Natural Gas Company, Inc., 40 percent by Ferret Exploration Company, Inc., and 10 percent by First Exploration Company. A preliminary announcement made in January 1981 indicated a "probable potential" reserve in excess of 25,000, 000 pounds U303. Drilling during 1981 and 1982 confirmed these reserves and indicated the presence of more than 30,000,000 pounds U308 having an average grade in excess of 0.25 percent U308. Wyoming Fuel Company was initially attracted to the area in 1978 by favorable regional geology for sandstone uranium deposits and weak radioactivity noted in regional oil and gas holes. Exploration drilling began in 1979 following the formation of the Crow 3utte Joint Venture. Drilling has continued up to the present, at which time the Joint Venture is ready to proceed with a pilot scale solution mine. Environmental baseline data have been acquired and the permit applications for the pilot scale mine have been submitted to the Nuclear Regulatory Commission and to the applicable state agencies in Nebraska.

Jan 1, 1984

By James J. Scott

Shale formations are the Nemesis of the Mining Engineer. Shales react to changes in environment in the most unusual and unpredictable manner. Increase in temperature may cause spalling, increase moisture and compression induced fractures may occur, and if a full face is exposed it may deteriorate due to atmospheric exposure. Combine only small amounts of shale in layered fashion with hard brittle competent rock and the whole structure may be fractured and fail due to stresses generated in and around the shale. In this paper the author will discuss failure mechanisms encountered under various field conditions and remedial action which may be employed by the engineer.

Jan 1, 1969