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The 70th Annual Meeting of the Minnesota Section of SME and the 58th Annual University of Minnesota Mining Symposium were held April 22-24, 1997, in Duluth, MN. About 450 attended both. The Fifth Annual Trade Expo, held during the meeting, was attended by a record 80 exhibitors. An SME short course on materials handling preceded the meeting. Iron-mining and the steel industries highlighted the meetings. Specific topics in the keynote addresses and technical sessions primarily concerned iron mining, iron- ore processing, product (taconite pellet) transportation and the steel market. Although the iron mining industry held center stage, several papers outside of iron mining were also presented. Iron mining in Minnesota contributes $1 billion to Minnesota's economy. According to the Iron Mining Association of Minnesota, more than 20,000 state jobs rely on the industry. Minnesota's iron mining industry came through tough times in the early 1980s, mostly because of worldwide competition. However, the industry has shown significant improvement in the last 15 years. A large share of the steel industry's competitiveness in the late 1990s is due to cost and quality improvements in the taconite mines. The taconite industry has become more productive, largely through the application of new technology. Since the early 1980s, Minnesota's taconite mines have nearly doubled the number of tons per worker-hour. Most of the taconite reserves in the United States are located in Minnesota's Mesabi, Vermilion and Cuyuna iron ranges. The Mesabi range alone contains an estimated 24. Gt (23.6 billion long tons) of mag- netic taconite. Since the 1950s, when taconite production first began, 1 Gt

Jan 1, 1997

By G. R. S. Smith

In any filtration, it is primarily the filter medium (cloth) and cake filtering properties that control the type of filtration equipment used and filtration conditions. The advent of new types of filter cloths, such as the membrane cloth discussed in this paper, can result in significant changes in filtration techniques and areas of application for filtration. For many suspensions, for instance, conventional filtration is uneconomic compared to gravity separation or not filtering at all (as with product recovery from dilute streams) because the solids are very fine, are hard to retain and build up filter pressure rapidly, and once retained are hard to remove. As a result of the developments discussed here, this is no longer the case. This technique and the use of the membrane filter cloth is well established. This filtration is currently being used for white liquor filtration in twenty-four mills worldwide in the chemical recovery step of the kraft process for producing paper pulp where it is replacing gravity thickeners in new plants. Filters up to 1000 sq. ft. (100 sq. meters) are filtering large volumes of solids from hot caustic solutions. The filtration materials and techniques discussed in this paper open the way to new methods and applications for filtration in the mining industry. It is not the intention of this paper to give a vigorous analysis of the different separations, but to outline some of the ways in which this filtration technique might be used in the mining industry.

Jan 1, 1989

By Jurgen Hahn

The paper reports on both, the design and decision making for the filters in a backfill plant in Europe as well as more then 10 years of operation and maintenance experience of the vacuum disc filters installed. It begins with the first step, the filter sizing based on a sample provided by the customer, followed by the commissioning of the filter units and reports on the development of the filter performance during the following 10 years of operation. Based on the physical properties of the sample and the process targets of the client for the backfill plant, the paper shows the logic steps taken in the laboratory to ensure the target moisture, determine the required filtration area and filter size as well as the selection of the ancillary units and the formulation of the performance guarantee. The paper discusses some issues with filter operation during the commissioning phase and the actions taken. Finally, the paper concludes by highlighting the gradual change over the more than 10 years of operation and how this change affected filter performance and operating costs.

Feb 1, 2024

By A. H. Summers

The La Choya mine is located 55 km south of Sonoyta in northwestern Sonora, Mexico. Mineralization is controlled by a 40 meter thick thrust fault zone which created a permeable host for the metal-bearing hydrothermal solutions. The ore body is mined by open pit using wheel loaders and truck haulage. Gold and silver are recovered from low grade ore by heap leaching followed by carbon adsorption.

Jan 1, 1997

By V. Srivastava, T. Ghosh

"Modeling and Simulation of SAG Mill has been widely used in design and optimization of mill performance in terms of its power draw, processing capacity and product size distribution. However, these models are solved under steady approximation and do not provide any information on mill charge distribution in real time. This paper attempts to characterize mill contents by solving Whiten’s first order contents based model in Matlab/Simulink environment. The parameters in the model such as breakage rate (S), discharge rate (D) and appearance function (A) were estimated utilizing process and design data collected from a gold mine operating in Alaska coupled with nonlinear parameter estimation scheme. This model is then utilized to predict dynamic response of other key operational variables such as mill power, bearing pressure, charge level and product size distribution. The transient response of mill behavior with respect to changes in feed size distribution, tonnage and mill feed water is also presented. This dynamic simulation approach can be used for practicing different control strategy and training purposes. The observed response of mentioned variables was validated utilizing dynamic response data from the plant to encompass operational characteristics of SAG Mill behavior. Keywords: SAG Mill, Dynamic Modeling, Simulation, Nonlinear Parameter Estimation. INTRODUCTION Grinding in mineral industry is one the most important steps in the process of size reduction and plays a crucial role in determining the overall economics of the milling plant. Much of the efforts focused on improving the process efficiency using modeling and simulation have been practiced by researcher and engineers. However, up till now these models were simulated under steady state approximation because of their complex nature and difficulty in programming them in a dynamic framework. Steady state simulations have been successfully utilized in circuit designing, capacity planning and pre-flowsheet optimization. The maturity in steady state models is because of its applicability and regular use in steady state simulation packages such as JKSimMet, Limn, ModSim, etc. With the advent of equipment such as SAG and AG mill has been a recent shift in the simulating these models using dynamic approach. Because of the economic benefits of these devices and ability to act both as a primary grinding device and as secondary or tertiary crushing device they have gained a large popularity and are now universal to any milling plant. However, these device poses a real challenge to engineers and researchers in terms of operation and control. The major reason attributed to problems faced is because the ore constitutes the major portion of the charge in these devices when compared to ball and rod mill. This rock charge is subjected to disturbance such as changes in feed size distribution and ore hardness which results in unstable operation and frequent mill stoppages. One way to prevent this is to measure and control these external variables, however, lack of available instrumentation and unavailability of sensors to measure these variables has foiled the understanding of complete process occurring inside the mill thereby, inhibiting development of proper control system."

Jan 1, 2017

The need for geological control in orebody estimation and modelling is self- evident to geologists and mining engineers engaged in practical day-to-day estimation. It is only fairly recently, however, that attempts have been made to incorporate explicitly such requirements into published accounts of geostatistical estimation; see, for example, Dowd and Scott (1982, 19841, Rendu and Readdy (1982), Dagbert et al. (1984), Dowd (1984), Benest and Winter (1984). In practice, many geological controls in automatic or semi-automatic estimation and modelling are essentially geometrical controls. The aim of this paper is to present two techniques for geological/geometrical control. Whilst the applications are new, neither technique is entirely original and both have been adapted from other fields and sources. Both techniques are, in some sense, types of estimators and/or interpolators of shapes. The first is a method for fitting spline surfaces to control orebody boundary estimation and to unroll orebodies. The second is an application of Minkowski addition to interpolate shapes such as orebody outlines or stope boundaries and to control estimations.

Jan 1, 1986

By Robert J. Watters, Peter C. Kelsall, Joseph G. Franzone

Two separate studies investigated the compressive strength of basic igneous rocks and its relation to index properties such as porosity, density and soundrave velocity. The rocks tested were weathered dolerite from S. W. England and vesicular lavas from California. In both cases strength was affected considerably by porosity. In the dolerite, strength was also affected by fissures (microcracks) which were formed in the parent rock by shearing and later accentuated by weathering. While test results show that porosity, density and sound velocity are not reliable indices of rock strength, these properties are useful in interpretation of strength test results. Index testing can be used to classify samples according to similar behavior and to recognize the influence of fissures.

Jan 1, 1986

By Steven J. Stokowski, Frederick M. Bodycomb

This chapter deals with the use of industrial minerals in insulating materials used to control our thermal and acoustical environment. There are numerous products on the market used for thermal and acoustical insulation; they consume substantial quantities of a variety of industrial minerals. Following is a brief review of the theory and function of insulating materials. Acoustics is the science of sound, and architectural acoustics deals with sound in buildings. If this definition is broadened to include transportation vehicles, it is this end use for which acoustical insulations are primarily manufactured. Sound is defined as the auditory sensation in the ear, or the disturbance in a medium which causes this sensation. Acoustical insulation is used to reduce or eliminate noise, defined as unwanted sound. Noise control may be accomplished by the reduction of sound radiation at the source, by utilizing sound reducing construction methods such as staggered studs, etc., to control sound transmission, or by using sound absorbing material on walls, ceilings, and floors (Rossing, 1985). Acoustical insulation functions by absorbing the energy in sound waves in a porous material. As the sound waves penetrate the pores, they are dissipated by reducing the amplitude of vibration of the air molecules by contact with the pore walls, with subsequent conversion of the sound energy to heat energy. Acoustical insulation is generally highly porous, 1.3 cm or greater in thickness, and has interconnected pores. Acoustical insulating materials include fibrous vegetable or mineral matter and cellular organic and inorganic material, such as natural or manufactured foams (Sabine and Moulder, 1979). Acoustical materials are most commonly porous boards and tiles, which are often composite materials with perforated facing. Roof insulation board and lightweight concrete can also contribute to the absorption of noise. Thermal insulation is defined as material used to control the flow of heat. It may be used for heat control from low cryogenic temperatures (below -100°C) to in excess of 2 200°C for applications such as ablative shields for spacecraft. Heat transfer occurs by conduction, convection, or radiation. Conduction is the transfer of heat without the movement of the conducting medium, as through a metal. Heat convection through a liquid or gas takes place by movement of the medium. Forced convection is the basis for heating and cooling equipment, utilizing pumps or blowers to transfer the thermally conditioned fluid. Free or natural convection occurs due to density differences in the fluid. Radiation is the transfer of energy in space (Eckert, 1985). Conduction of heat through a solid is reduced by insulating the body with foams, or fibrous or small celled granular material. Heat transfer through a gas (convection) is controlled by creating many small pores which inhibit the movement of the fluid, substituting a gas of low thermal conductivity, or evacuating the space. Heat radiation can be reduced by the use of materials that reflect or absorb the energy (Glaser, 1967). Thermal insulating materials may be vegetable or mineral fibers, organic or inorganic particles, or foams with small pores, generally used to form a low density thermal barrier. They may be blocks, poured lightweight cementitious materials, bricks, etc.

Jan 1, 1994

By S. J. Schatzel, K. M. Ajayi, Z. Khademian

The integrity of unconventional shale gas well casings positioned in the abutment pillar of a longwall mine could be jeopardized by longwall-induced deformations. Under such scenarios, the surrounding fracture networks could provide pathways for gas flow into the mine creating safety concerns. To provide recommendations for developing guidelines that ensure a safe co-existence of longwall mining and unconventional shale gas production, this study evaluates the impact of parameters that could affect potential shale gas flow into the mine in the event of a casing breach using a discrete fracture network (DFN) model. These parameters are evaluated using a conceptualized DFN realization that is representative of the fractured zone in the overburden, and the range of parameter variations are within values validated with field measurements. The results show that a decrease in fracture aperture (potentially due to longwall-induced stress in the likely vicinity of the breach location) reduces the potential gas flow to the mine by a significantly higher proportion. A 50% decrease in the aperture of the fracture that directly transports the gas from the casing breach location reduces the gas flow to the mine by over 70%. Similarly, changes in the fracture water saturation level significantly affect the gas flow. In all cases, the potential gas flow to the mine is higher if the casing breach occurs at an increased gas well pressure. These findings provide critical information regarding the impact of each of the parameters associated with gas flow in the event of a shale gas casing breach near a longwall mine and could help towards the development of guidelines to ensure a safe coexistence of both industries.

Mar 2, 2022

By Y. K. Yen, J. D. Miller, C. L. Lin

A PC image-based, on-line coarse particle size analysis system is being developed for the control of crushing and grinding circuits. Initial results had indicated that the system is accurate when tested with irregularly shaped particles which are stationary and do not overlap with each other. Now the system has been successfully tested in the dynamic mode with a moving belt conveyor. On-line size analysis for actual plant operations is discussed and includes: (1) the video system with respect to lighting and data acquisition requirements for a rapidly moving belt and, (2) image sampling, specifically the number of observations needed for accurate sampling and the total time required to perform the calculations for a representative data set.

Jan 1, 1993

The Waste Isolation Pilot Plant (WIPP) is adding a third fan to operate in parallel with, and supplement, its two existing main fans. An engineering analysis conducted in 1995 identified the need for improved system availability and efficiency. The WIPP, located near Carlsbad, New Mexico, is a U.S. Department of Energy (DOE) Carlsbad Area Office facility designed to permanently dispose of U.S. defense-generated transuranic waste in a deep bedded salt deposit. Engineers at the WIPP performed a feasibility analysis for either modifying, supplementing, or replacing its two main mine fans. Since the centrifugal fans were installed in 1988, multiple operational and performance concerns have been identified. A comprehensive engineering study was conducted (K. McDaniel, et al., 1997) to: identify and quantify operational concerns, evaluate possible alternatives, and recommend an optimum solution. The study indicated that adding a third single-duty centrifugal fan similar to the two existing fans, and equipping that fan with Inlet Van Controls (IVCs) was the best choice. This alternative provided the most desirable combination of operational readiness, and improving system performance. The fan installation project accommodates several operational and scheduling constraints. WIPP is scheduled to receive waste in May 1998. This milestone is proceeded by an operational readiness review. Fan installation could not be allowed to compromise the WIPP's ability to declare facility readiness and had to minimize operational disruptions during the system tie-in. All engineering for the project is completed and physical modifications started in July 1997. The project will be completed in early 1998.

Jan 1, 1998

By W. J. Whiten

A rule-based control system was developed for a 7-foot Hydrocone crusher with automatic set regulation, based on operating data collected in the field. When implemented in a plant PLC, the system was found to behave as predicted. Benefits included a significant reduction in the frequency of control actions, the incidence of power overloads, and the standard deviation of feeder speed, whilst maintaining crusher performance.

Jan 1, 1992

By John M. Anderson

This paper examines the methods available to improve climatic conditions around a deep, high production longwall district of a British coal mine using results from a computer model. Such methods include the provision of increased ventilation quantities, the application of refrigeration, the reduction of heat input at source and the use of alternative ventilation systems. An approach to the solution of a climatic problem is explained with reference to other coal mine contaminants and a cooling strategy for deep high production British coal mines is described.

Jan 1, 1987

By Z. M. Zavodni, M. K. McCarter

This paper identifies physical conditions responsible for past instability of the Main Hill area in Kennecott Copper Corporation's Bingham Canyon Mine, Bingham Canyon, Utah, and describes successful stabilization techniques employed in this slide zone. Geotechnical highlights of recent slides are presented, including monitoring, geological engineering data collection, hydrology, physical rock properties, and stability analyses. Local conditions responsible for slope movement in the Main Hill zone are: (1) high pore water pressure that causes a substantial decrease in real and effective material strengths; (2) continuous structural systems that allow sliding in the more competent rock zones; and (3) broad areas containing fractured, altered , and incompetent rock and soil- like materials. The failure mode is structurally controlled and involves a circular-type soil failure in the toe region initiated by excessive pore water pressure. A surface mapping method is presented which assigns rock mass quality on the basis of block size and rock substance strength. This site characterization technique has successfully predicted slide boundaries and failure modes; used in conjunction with laboratory determined shear strengths, it has provided basic input for calculating slope safety factors in the Main Hill slide zone.

Jan 1, 1977

By A. C. T. Bigg

Heavy media separation is one of a number of ore-concentration techniques for coarse? feed which, when the ore is amenable, offers economic advantages in the mining stage and/or the processing stage. In mining, simpler and cheaper methods may be used if a greater proportion of waste material can be included in the mining blocks that can later be re-moved efficiently at a coarse size. In the mill, pre-concentration can mean considerable savings in capital and operating costs by down-scaling of equipment sizes particularly in the grinding section. Conversely, throughput may be increased using the equipment already in-stalled in the concentrator.

Jan 1, 1988

By L. Gertsch, R. Gustafson, J. Rostami, C. Swope

Development of a permanent human base on the moon for exploration requires a self-sustaining system. Such a system entails the production and processing of limited amounts of raw material on the moon. Any mining and construction activities on the moon can only be performed by a robust excavation machine that can excavate a variety of material, from loose surface regolith to consolidated (frozen) regolith with embedded rocks in the mixture. Meanwhile, a limited amount of information on lunar regolith is available to develop and optimize a machine for lunar ground conditions. Therefore, any excavator designed for use on the lunar surface should have the ability to adapt to a wide range of operating conditions. A prototype cutterhead for the lunar excavator was built and tested at the Kennametal facility in Latrobe, PA. This paper discusses the results of initial material characterization, as well as full-scale tests of a prototype cutterhead in relevant material. A brief review of anticipated production rates under various assumed ground conditions is also presented.

Jan 1, 2010

By Yuemin Zhao, Daniel Tao, Rick Honaker, Maoming Fan

"Froth flotation is the most widely used method of separating fine coal, especially coal with coking properties. However, froth flotation is not efficient for treating ultrafine coal and coarse coal particles. Our previous fundamental test results demonstrated that cavitation-generated nanobubbles around 700 nm in diameter can significantly improve coal and phosphate flotation performance over a wide particle size range. In this study, the effect of nanobubbles on the flotation performance of different particle size fractions of coal was investigated using a bank of 10-L flotation cells, a specially designed 50-mm inside diameter column and a 152-mm inside diameter column. It was found that nanobubbles that were either directly formed on or subsequently attached to the surface of coal particles during the froth flotation process improved flotation efficiency. The use of nanobubbles in a bank of mechanical cells flotation and column flotation significantly increased the flotation recovery at a given product grade. Nanobubbles increased the flotation rate constants of different coal particle sizes. The presence of nanobubbles in flotation slurry could extend the lower and the upper particle size limits for effective coal flotation.IntroductionFor minus 0.6 mm fine coal or minus 0.15 mm ultrafine coal particles, froth flotation is known to be the most efficient and the most cost-effective separation technique. However, flotation efficiency decreases sharply with ultrafine and relatively coarse coal particles. Studies have shown that the low flotation efficiency of ultrafine particles is mainly due to the low probability of bubble-particle collision (Yoon et al., 1989; Ralston and Dukhin, 1999). Enhanced flotation of fine and ultrafine coal can be achieved by increasing collision and attachment probabilities.The top size of particles that can be recovered by flotation depends on the combination of mineral properties and flotation devices. Turbulence in flotation devices is an important factor that affects the stability of bubble-particle aggregates. Even in the flotation of fine particles, bubble-particle detachment can significantly influence the kinetics of flotation taking place in mechanical cells, which provide intensive turbulent agitation (Deglon et al., 1999). Coarse particle flotation is more difficult, because increased agitation is required to maintain particles in suspension and coarse particles are more likely to detach under turbulent conditions (Mankosa and Kohmuench, 2002; Soto and Barbery, 1991). More efficient attachment of particles and improved flotation rate has been observed when tiny bubbles coexist with conventional-sized flotation bubbles (Attalla et al., 2000; Tao et al., 2010; Fan et al., 2010a, b, c, d; Fan et al., 2012)."

Jan 1, 2015

By Gerrit V. R. Goodman, Fred N. Kissell

The issue of miner safety in case of an underground mine fire has been extensively examined by both government and industry. These efforts have intensified in recent years following a number of fatal fires at underground coal mines. As a result, there is an increasing interest in the reliability of coal mine escapeways during a mine fire. This paper discusses the use of fault tree analysis for evaluating escapeway reliability. A fault tree is developed using standard logic formulations. It is later evaluated using commercially available software. The computer model uses Boolean reduction to obtain the minimal cut sets and minimal path sets of the tree. A brief analysis is also conducted to determine the occurrence probability of the TOP event. This study shows that fault tree analysis is a viable means of analyzing escapeway reliability. The cut and path sets reveal those event sequences leading to fatalities. Such information is useful in safety training and accident prevention. The probability of the TOP event shows the frequency of occurrence for fatalities in an underground mine fire. The usefulness of this value, however, is limited by the accuracy of the data for the initiating events. For mining events, the data is difficult to estimate precisely.

Jan 1, 1989

By Gülhan Özbayoglu, Yusuf Ziya Akgök

The effect of cooling rate on the flotation behaviour of copper slags of flash smelter plant in Samsun was investigated. Fresh molten slag was solidified in laboratory scale in three different ways. All the samples were characterized by chemical and mineralogical analyses. The chemical analyses showed that samples prepared from fresh slag had 0.9 to 1 % Cu with 40 % Fe and 30 to 32 % SO2. Old pit slag samples contained between 1 to 3% copper. Microphotographs showed that rapidly cooled slags showed fine size distributions, e.g. the copper grains in granulated slag had sizes in 1-2 microns. On the other hand, the size of copper grains in slowly cooled slags increased above 40 microns. Flotation tests carried out by using potassium amyl xanthate and Flotanol-C showed that slowly cooled slag reduced the copper losses in the tailing and improved the grade of concentrate. Under the light of laboratory investigation, the pit dimensions of Samsun Plant have been modified which resulted in a pronounced improvement of the grade and recovery of concentrate produced at Samsun slag flotation circuit.

Jan 1, 1995

By Patzen Wu, Chao-Ming Tsai, Shaw-Chii Wu, Yuan Lin

INTRODUCTION The development of nuclear industry in Taiwan requires an increasing supply of uranium. Uranium recovery from phosphate ores, becomes an important item of the R & D programs. Many countries have already started such a program. USA has set up an industrial-scale production plant; South Africa, Israel, Morocco and other countries have also engaged in the development of extraction technology of uranium from phosphate ores and started setting up the production plant. In Taiwan, a feasibility study of establishing the production plant was started in 1977. A pilot plant was completed, tested, and operated in 1979. The main source material. - phosphate ores is obtained from China Phosphate Company. The annual yield of the pilot plant has been planned to be one ton of ammonium diuranate (ADU). The Health Physics Division of Institute of Nuclear Energy Research (INER), Atomic Energy Council of Republic of China (ROC AEC), is responsible for the radiation safety control of the plant. The purpose of the radiation safety control is to collect radiation safety information of the plant of this type, to evaluate possible radiation hazards to the personnel, and to analyze the radiation safety of the immediate environment adjacent to the plant. Furthermore, the information and experience obtained are used as the basis for applying radiation safety control to the production plant. The main emphases of the radiation safety control are therefore the arrangement of radiation safety control areas and the collection and evaluation of the health physics data. This report includes the past one and half years' experiences of the radiation safety control of the pilot plant, the planning of the production plant with an annual yield of 10 ton ADU, and considerations given in improving the radiation safety control of the production plant. PILOT PLANT AND ITS OPERATION PROCESS The pilot plant occupies an area of 350 m2 and is a two-story rectangular building. Exits are provided by a front and a rear door. An additional small door at the central right side of the building is connected to the maintenance area located outside the main building. The interior of the building is divided into interconnected offices, laboratories and process area (Figs. 1 and 2). A stairway to the process area of the second floor is located in the central part of the first floor. The second floor offices are accessible by the additional front and rear stairways. The main process area of the first floor is furnished with plastic floor, and the second floor with poriferous iron-grid floor. The building is not furnished with centralized air-conditioning system. Individual air conditioners are, however, available to some laboratories. Because the back door of the building is frequently open, the product storage room is provided with a blower to maintain good ventilation. Natural uranium contents of phosphoric acid solution vary in the range from 0.07 to 0.11 kg/m3. The process consists mainly of the uranium concentration cycle and the purification cycle. A flow diagram of the process is shown in Fig. 3. CONSIDERATIONS GIVEN FOR RADIATION SAFETY CONTROL AND THE ESTABLISHMENT OF RADIATION CONTROLLED AREAS The radiation safety control of the pilot plant is carried out on the basis of the considerations listed below:1,2 1) Since the wet process is adopted, and the flow of the radioactive material is confined to closed pipes and containers, air contamination is therefore not too much of concern. 2) The concentrations of radioactive material of the whole process are mostly less than 10 ppm. An exception is the final ADU product after precipitation and centrifugal separation, which contains up to 50% natural uranium. It is therefore necessary to apply radiation safety control to the process area where

Jan 1, 1981