Search Documents

By W. W. Roepke, B. D. Hanson

A major problem facing the coal mining industry today is the need to meet more stringent dust standards due to quartz. When secondary suppress ion is not adequate, the time-consuming and costly cut-and-try method of modifying the mining machine is used in the hope that it will reduce dust generation. The Coal Cutting Technology Group, at the Bureau of Mines' Twin Cities Research Center, has developed an inter-active computer program for drum- type cutting systems to help identify, in advance, modifications that offer the best potential for reducing dust. The program, Relative Dustiness Indicator (REDI), evaluates machine dimensions, seam characteristics, and operator-controllable variables for dust generaton, energy, forces, and product ion.

Jan 1, 1986

By Don U. Deere

The tunnel boring machine (TBM) can be a magnificent tunneling device under optimal rock conditions. Such ideal conditions would include good Rock Material Characteristics (compact, uniform; low to medium strength, hardness, and abrasiveness); good Rock Mass Characteristics (few joints and shears; unweathered); and good Geologic Environmental Characteristics (above groundwater level and moderate in-situ stress). Such idealized rock conditions would eliminate support problems, fallout at face and grippers, frequent cutter changes, and water problems. Daily advance rates of 50 m would be commonplace. Unfortunately, nature seldom provides the ideal geologic characteristics. The challenge to the geologist, machine manufacturer, and contractor is to provide equipment and procedures to best handle the adverse geologic features, once identified.

Jan 1, 1981

By Bart Lorang

Mining and mineral processing companies have historically leveraged technology and science to the fullest to reduce costs and improve product. Information technology is arguably one of the fastest moving technologies used by the mining industry. However, the business model for managing that technology and IT professionals often is fundamentally the same model that evolved from 1960's mainframe era. This paper will present a perspective of today's technology; review emergent computing technologies and attempt to id- advancements in computing anticipated in this decade. It will then discuss how the traditional IT model fits the technologies of today and the next decade. It will suggest roles IT professionals may play in the future to best leverage these technologies.

Jan 1, 2002

By D. R. Nagaraj

The practice of nonsulfide minerals flotation can be best characterized as an evolutionary blend of scientific theory and art. Although extensive fundamental studies have been carried out in the past several decades, and significant theoretical aspects have been developed, plant practice has developed the art form, often ahead of the theory, which is somewhat in contrast to sulfide minerals flotation. Several excellent review articles have been published in the past highlighting both the theoretical aspects and plant practice. An overview of nonsulfide flotation is presented here. Major differences in sulfide and nonsulfide flotation are highlighted. An assessment of the state of nonsulfide flotation, recent advances made in flotation processing, and industry needs are also given.

Jan 1, 1999

By S. P. Mehrotra, P. C. Kapur

A phase-species classification is suggested for the mathematical models of flotation kinetics. Important models are discussed and the structure of their rate constants and parameters is analyzed. Split or enhancement factors are formulated for different kinetic models. The steady state dynamics of the flotation circuits can always be described in terms of these factors. For simulation of circuits, feed is characterized in a formal manner starting from a multivariate distribution of particles in flotation rate, size and mineral content. Synthesis of optimum circuits which simultaneously searches for the best process variables and structural parameters from a generalized master network is described. Trends in the areas of search algorithms, role of middlings and feed identification etc. are indicated.

Jan 1, 1989

By S. P. Girrens

A coupled finite element geomechanical- hydrology code is currently under development for application to the problem of predicting groundwater disturbances associated with mine subsidence. The structural-fluid coupling is addressed by calculating the subsided mine geometry, with emphasis placed on determining the strata disturbance and locating damaged regions, for input into a hydrology code, which determines localized volume flow rates and aquifer fluctuations. Benefits from coupling will be best realized when field measurements, an additional aspect of the study concurrent with analytical investigations, indicating the relationship between increasing rock strain and increasing permeability are incorporated into hydraulic material descriptions. Hydrologic and struc- tural calculations are presented to demonstrate computational capabilities applicable to mine subsidence

Jan 1, 1982

By R. J. Lutton

The U. S. Army Corps of Engineers is seeking empirical slope data from mining companies and other organizations to help establish guides for engineering Judgment in crater excavation for canals and other civil works. Slopes from about 100 open pits and other excavations range in heights to greater than 1000 ft. Factors known or expected to affect stability (and optimum slope inclination) are: geological structural orientation, geological structural ordering, method and technique of blasting, design life of slope, groundwater conditions, depth of excavation, climate, and height. These and other more subtle factors appear to combine and produce an overall effect brought out best on a family of empirical curves relating slope height and inclination.

Jan 1, 1968

By W. J. Turbeville

The subject of this discussion is timely. The U.S. phosphate industry is suffering the throes of depression. It's plight is a matter of widespread concern. The future role of the U.S. industry in world markets is of particular interest. If we should prognosticate phosphate supply-demand on the basis of recent history, we would face a puzzling choice of scenario. In 1980, perhaps the best year ever for U.S. phosphate, 54.6 million metric tons of phosphate rock entered the market place. Of this, more than half was exported -- divided almost equally - as rock or phosphate fertilizer. During the last half of 1981 the situation had begun to change.

Jan 1, 1983

By B. V. Cooper

The word "research" has been used in the title of my presentation somewhat against my better judgement. There are many definitions of the word. But the one I like best comes from Webster's New World Dictionary. It reads: "Careful, systematic, patient study and investigation in some field of knowledge, undertaken to discover or establish facts or principles. ..." I like that. In only 9 words, the definition conveys to me the very essence of what should be going on either in or for the coal industry. Unfortunately, not enough coal-related research is going on. And much of what is being done is, in my view, not really as effective as it might be.

Jan 1, 1983

A bearing isolator is a noncontact, nonwearing, permanent bearing protection device. It has a rotor and a stator, and the two are unitized, so that they do not separate from one another while in use. The rotor turns with a rotating shaft, while the stator is pressed into a bearing housing. The two components interact to keep contamination out of the bearing enclosure and the lubricant in. Bearing isolators do not require lubrication or any particular shaft finish or condition. The best bearing isolators are made of metal, usually bronze. They use a vapor-blocking feature that inhibits the free transfer of vapor contamination when the rotating equipment is cycled on and off.

Jan 1, 2004

By H. R. Coles

Test work conducted in the 6.4 and 10.52 m Aerofall Mills at the Iron Ore Company of Canada Carol Project showed that the conventionally used ?deflector?-type liners which form the basic principle of Aerofall Mill grinding did not necessarily provide the best grinding performance. A new design, using low profile liners incorporating radial ribs of a proper height, actually improved the mill throughput in the order of 9 to 20% without sacrificing grinding efficiency. In addition, the new design reduced liner weight and scrap losses, which resulted in a reduction of liner consumption by 25%. It provided better protection to the mill shell and reduced the overall maintenance cost for the mill

Jan 1, 1980

By M. Dobbins

The advent of the more efficient and effective rare-earth roll (RER) separator in the early 1980?s began a new era of dry magnetic separation. The RER units quickly became the separator of choice within the materials processing industry. Though RER separators are now commonplace throughout the world, only modest advancements have been made to the original design. This paper details recent, more significant, rare-earth magnetic separation developments. These developments maintain the best features of existing technology while minimizing shortcomings. The discussion includes discerning features that aid in better metallurgical performance. Also discussed are improved mechanical aspects that allow for both easier operation and maintenance. Performance details from various test programs are included.

Jan 1, 2009

By Steve Kral

Commodity price down cycles are a fact of life in the mining industry. And companies pre-pare for them as best they can. Evenso, operations are still curtailed or closed during those cycles, profits shrink, layoffs are inevitable and many companies do not survive. However, one of the few good things that occurs during down cycles is the new, innovative exploration, mining and processing technologies that come about during hard times. To survive the lean times, the mining industry turns to improved technology to decrease costs and hold the bottom line. And, because mining is a cyclical business, each down cycle brings about technology improvements that carry over into the good times.

Jan 1, 2004

The authors summarise the development and recent advances in the reconstruction and visualisation of three-dimensional objects from point data and describe applications to the reconstruction of orebody shapes from drill-hole and other data. In particular, Dijkstra's algorithm is proposed and implemented as a means of optimal reconstruction of complex orebody and topographical shapes from irregularly located sample data. The surfaces of the shapes are constructed from triangular tiles and the algorithms proposed by the authors are guaranteed to find the optimal set of tiles that "best" construct the surfaces on the basis of specified objective criteria. The algorithms are illustrated by applications to a complex silver/gold/zinc/lead deposit.

Jan 1, 2002

By M. Dobbins

The advent of the more efficient and effective rare-earth roll (RER) separator in the early 1980s began a new era of dry magnetic separation. The RER units quickly became the separator of choice within the materials processing industry. Though RER separators are now commonplace throughout the world, only modest advancements have been made to the original design. This paper details recent, more significant, rare-earth magnetic separation developments. These developments maintain the best features of existing technology while minimizing shortcomings. The discussion includes discerning features that aid in better metallurgical performance. Also discussed are improved mechanical aspects that allow for both easier operation and maintenance. Performance details from various test programs are included.

Jan 1, 2010

By Lawrence M. Gochioco

One of the best kept technology secrets in U.S coalmining history involved a robust coal geophysics program used by a local coal company to detect and map various geologic anomalies and man-made structures ahead of mining for nearly 15 years. Several original mine plans were changed as a result of findings from two-dimensional (2D) and three-dimensional (3D) seismic data. They indicated the presence of geologic anomalies in reserve areas that could adversely impact future mine development and longwall production. By combining the surface seismic and exploratory drilling methods, the coal company learned how to properly leverage its risk by gathering a lot of useful subsurface information before making major commitments.

Jan 1, 2005

By Emmanuel V. Manlapig

The variables involved in a complex process like flotation can be classified as follows: a. Disturbance variables - which are undesired properties of the process input which affect the value of the process output but which are not subject to adjustment. They are the result of changes in the properties of the feed, like changes in head grade, flow rate, fineness of grind, etc. b. Manipulated variables (sometimes referred to as process variables or control variables) -which are those that are adjusted - reagent addition, aeration, pulp level - in order to compensate for the disturbances in the properties of feed. c. Performance variables (sometimes referred to as controlled variables) -which are those whose values measure the performance of the process. They are properties of the process output such as grade and recovery. The function of a control system is to maintain the process performance equal to the control objective in spite of the disturbances by adjusting the manipulated variables. Attempts at developing automatic control systems for mineral processing operations date back to the thirties and in many of these attempts the results were not surprisingly poor and un-stable. The poor results brought indifference and suspicion towards automatic control on the part of operators and management. The reasons for the apparent failure of these attempts were two-fold: a. the lack of adequate understanding of the behavioural responses of the process from the control point of view, and b. the lack of reliable control instrumentation which could withstand the harsh environment in mineral dressing plants. Many operators had accepted the fact that control of mineral dressing could be best conducted manually. In the case of flotation circuits, control had been virtually based on the skill and experience of operators particularly their ability to identify and rectify poor flotation performance aided by results from the laboratory (chemical) analysis of regularly collected samples from strategic points in the circuit which are at best, hourly collected samples.

Jan 1, 1978

By Christopher R. Winter

Mining companies have sharpened their refocus on their tailings management strategies in recent years. Mining companies with tailings storage facilities that use the upstream construction method have been challenged to track the evolution of industry standards, assess risks, revise design, and communicate design revisions with regulators. While many aspects of best practices and industry standards have evolved in recent years as an attribute of continual improvement, the controlling standard in the design of many upstream dams is understanding the foundational strengths of hydraulically deposited tailings. Following best practices and industry standards, Hibbing Taconite Company managed by Cleveland-Cliffs, began the re-evaluation of foundation strengths underlying a system of upstream dams at the company’s iron ore mine tailings storage facility in northern Minnesota. Initial steps in the re-evaluation require reanalysis of design parameters and recommendations by the Engineer of Record to the Owner, which was followed by a series of meetings with the Technical Review Board to determine an initial path forward. Once a path forward and preliminary design parameters were determined, the Owner engaged with the State Dam Safety Engineer to discuss and seek approval of the plan. With continuous regulatory engagement throughout the process, further refinement of the design parameters for the hydraulically-placed tailings foundations underlying upstream dams began with field and lab geotechnical investigations. Following a review of risk assessments and trigger actions response plans, Hibbing Taconite revised its tailings storage facility operating plans and budget for the coming years. Based on the findings of the re-evaluation, reanalysis, and refinement of parameters, a paradigm shift was realized with the hydraulically placed tailings foundation strengths underlying the upstream system of dams. This paper explores the path that the Hibbing Taconite Company followed to understand the paradigm shift and construct downstream improvements. The plan involved tailings re-characterization, dam design revisions, operating plan reconciliation, budget revisions, wetland permitting, dam safety permit amendments, storm water prevention plans, borrow materials studies, new concrete decant structures and the pursuit to recognize and be consistent with industry standards.

Feb 1, 2024

By Gale F. Hoffnagle

INTRODUCTION On November 15, 1990, President Bush signed the Clean Air Act Amendments of 1990. These Amendments cover many aspects of air pollution control. The provisions which seek to control emissions of "air toxics" may, however, be the most far-reaching and will potentially have the greatest effect on American industry. The Administration has estimated that by the year 2005 industry will be spending $6.7 billion per year on air toxics control. Meanwhile, the Business Round Table has estimated that the price will be far higher, up to $62 billion per year, depending on how EPA and the States implement the program. BASIC REQUIREMENTS Any "major" source of emissions of 189 air toxics will be required to install "MACT." The translation of this statement requires some definitions: •MAJOR SOURCE - A facility (a contiguous property under single ownership and control) which has actual emissions of 10 tons or more per year of any single one of the air toxics or 25 tons per year of any combination of air toxics. •AIR TOXICS - Congress has provided a list of the 189 chemicals on this list. Those that may be important to the mining industry are shown on Table 1. This list can be changed by petition or by EPA. •MACT - Maximum Achievable Control Technology is to be defined by EPA for each industrial source category. EPA says there are about 400 categories. The Act defines MACT as: "the average emission limit achieved by the best performing 12% of the existing sources ... for categories with 30 sources or more" or, "the average emission limitation achieved by the best performing 5 sources in the category." TABLE 1 SELECTED AIR TOXICS FROM CLEAN AIR ACT LIST IMPORTANT TO MINING INDUSTRY Antimony Compounds Arsenic compounds (inorganic including arsenic)' Beryllium Compounds' Cadmium Compounds Chromium Compounds Colbalt Compounds Cyanide Compounds (dissociation compounds) Lead Compounds' Manganese Compounds Mercury Compounds' Fine Mineral Fibers Nickel Compounds Radionuclides (including radon)1 Selenium Compounds 1Previously listed under NESHAP 2The Administration may not list elemental lead as a hazardous air pollutant.

Jan 1, 1991

By Pooyan Asadollahi, Praveen Krishna, Michael Joye

"Durability design for underground structures is an increasing focus of designers and owners in the underground construction industry. Many owners have expanded their requirements for durability design, with specific requirements for structure lifecycle and designer certification of structural durability. This paper describes current trends and best practices including: defining the underground structure lifecycle, historically durable underground structures, design methods for underground structure durability built of reinforced concrete, and durability of materials. Criteria to be used for defining end of structure life and owner’s maintenance responsibilities are crucial to lifecycle contract requirements. Current practices of several major owners are presented. Design methods are presented including United States code requirements. Current best practices for enhancing the durability of materials used in underground construction are discussed including: low permeability concrete, steel reinforcement concrete cover, the use of steel fiber, and testing for verification. INTRODUCTION Durability design is increasingly being recognized as an essential component of good design practice. Infrastructure owners recognize that to serve the public interest, constructed facilities must be lasting and durable. The public understands that structures with limited service life result in increased costs and add to their daily inconvenience with frequent repair and reconstruction. Engineers are increasingly asking not only is the structure strong enough but will it last for generations. Durability design requirements are no longer just adherence to some accepted practices, but are based on analytical approaches, with results that can challenge our beliefs in what construction materials and details result in a durable structure. This paper describes current industry requirements and practices for durability design of underground structures, and offers some suggestions regarding future trends and developments. SERVICE LIFE DEFINITION The service life of a structure is the sum of the time to onset of deterioration, called initiation period (ti), and the subsequent time period of deterioration ending when the structure is no longer functional, called propagation period (tp). Figure 1 shows a conceptual service life diagram. These time periods can be substantially affected by the level of maintenance performed during the life of the structure."

Jan 1, 2016