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By J. Herbst, A. J. Lynch, E. V. Manlapig, G. C. Throne, J. S. Hall, G. Poling

Modelling of industrial sulphide flotation based on data collected in several flotation plants is discussed. A mechanistic approach is used in which it is recognised that flotation is a two stage process with concentration occurring both in the pulp and in the froth. The important features of the model, which is a kinetic model, are – 1. for each particle species there is a range of flotation rates which corresponds to the range of particle sizes, 2. the flotation rates of the liberated gangue particles which have no hydrophobic properties are dependent on the flotation rate of water and are controlled by variables such as the air and frother addition rates, and the pulp level, 3. as an approximation the valuable sulphide particles may be regarded as being present in two groups with high and low flotation rate constants, 4. increase in the addition rate of collector tends to increase the proportion of sulphide particles which are in the high flotation rate constant group. The actual flotation rate of each group of particles is a combination of an "inherent" flotation rate and a flotation rate which is dependent on the flotation rate of water, at particular air and frother addition rates and pulp levels there is a physical limit to the rate at which particles can be transported into the concentrate and this is recognised in the

Jan 1, 1976

By H. W. Hitzrot

Introduction Mechanical classifiers consist of a settling tank with parallel sides and a sloping bottom equipped with a mechanism which continuously agitates the pulp and removes the settled solids. The functions served by mechanical classifiers include the following: (1) allow the particles larger than the desired size to settle in the tank and provide an overflow product with a minimum of oversize particles, (2) produce an overflow product of sufficiently high solids content to meet the requirements of the subsequent processing steps, (3) agitate the pulp and permit separation of the entrapped undersize particles so they can report in the overflow product, and (4) drain and remove the underflow solids from the settling pool. Various types of mechanisms have been used to agitate the pulp and remove the settled solids, which include: (I) endless belt and chain drags, (2) reciprocating rakes, (3) helical flights mounted on a rotating shaft which extends through the settling pool, (4) helical flights inside of a rotating drum which contains the classifier pool, (5) troughed conveyor belts forming the settling pool in the concave curve of the belt closely following the tail pulley, and (6) low-speed impellers agitating the underflow settled in the apex of cone-type mechanical classifiers.23 The principal use of mechanical classifiers has been in closed¬-circuit wet grinding; however, this application has been widely displaced over the past few decades by the hydrocyclone. The hydrocyclone installation, including its feed pump, offers lower capital costs and requires less floor space. Nominally it produces an overflow prod¬uct of higher solids content, compared with a mechanical classifier, for comparable classification size up to 400µm (35 mesh). However, these advantages of the hydrocyclone are being gained at the sacrifice of some of the advantages of the mechanical classifier. The mechanical classifier requires less power and has lower maintenance costs than the hydrocyclone and its feed pump. The underflow product from the mechanical classifier can have a higher solids content and contain less entrapped undersize particles than the comparable product from the hydrocyclone. Consequently, it is capable of operating at a higher classification efficiency. A reduced circulating load24, 25 results under these conditions in a closed-circuit grinding application. Other applications for mechanical classifiers include desliming, dewatering, and washing operations. Sand-slime separation may be achieved using one or more stages of mechanical classifiers. Typical applications would include washing and deslimining of concrete aggre¬gate or sand; glass sand; abrasives; oyster shells; phosphate rock; iron, nickel, and chromium ores; alumina; zeolites; solar salt; and precipitates from chemical processing. As an example for the latter, Bitzer26 recommended the use of mechanical classifiers for countercur¬rent cementation-in-pulp of copper from the leach liquor. Similarly, mechanical classifiers are used in uranium processing27 for separation of the barren sands from the pregnant leach solution. Depending on the particle size and the effectiveness of the sand¬slime separation, the sand product from mechanical classifiers may be drained to solids content approaching 84%. Thus, mechanical classifiers are frequently used as dewatering equipment for various applications, such as: 1) Make a product having suitable solids content for subsequent transport by belt conveyor. 2) Provide a drained product to reduce cost of drying. 3) Provide a drained, washed, heavy sand product for return to the circuit. 4) Recover fine values from dilute plant effluents from coal, sand, phosphate-rock, and iron-ore washing plants and from steel-mill flue¬dust scrubbers. 5) Drain residual reagents of a preceding process stage prior to conditioning with reagents of different characteristics, e.g., cationic¬anionic flotation of phosphate rock, iron ore, etc. Design and Operating Features The proper selection of mechanical classification equipment re¬quires that the properties of the solids and liquid are adequately de¬fined. The following descriptive information regarding the solids is desired: feed rate, chemical and physical composition, density, tem¬perature, size analysis, and desired separation size. For the liquid used, the following data would be needed: feed rate, density, viscosity, pH, and temperature. Settling Area. The pool area required to permit a particle larger than the separation size to settle depends on the density and shape of the particle and on the density and viscosity of the pulp within the classifier pool. These criteria of the solids and pulp determine the settling rate which, in turn, determines the settling area required. Determination of the settling rate by long-tube batch tests can be used to calculate the settling area. A theoretical approach for estimat¬ing the settling area requirements is discussed in Chapter 1, Classifica¬tion Theory. This procedure can be used when neither test data nor empirical data from similar operations are available. Data on settling-area requirements and settling rates have been compiled by the manufacturers of mechanical classifiers. The approxi¬mate settling area required for a particular separation size can be estimated by using the curve shown in Fig. 65. This curve applies for closed-circuit grinding applications. For dilute velocity classification in open circuit, desliming, the length of the overflow weir, W, multiplied by the weir's mean distance from the feed opening, E, is used as the design criterion, instead of the settling area, in sizing the classifier. The area requirements, W X E, for dilute velocity classification can be expressed in terms of volumetric flow, Q, and settling rate, Rs, as follows: W x E = Q/(18.06 Rs) where W and E are feet, Q is gallons per minute, and Rs is inches per second. Overflow Weir. The hydraulic head, and thus the velocity at which the overflow crests the overflow weir, is one of the factors controlling the particle size of classification. Consequently, the length of the overflow weir must be designed to provide the overflow velocity which allows the particles larger than the desired size of classification to settle in the working area of the pool. Obtaining the necessary

Jan 1, 1985

By C. J. Pritchard, R. D. Jacksha, K. V. Raj, C. Sunderman

"In underground metal/nonmetal mines, repeated short-term exposure to high levels of airborne contaminants can become a serious health issue. Currently there are no common mechanisms to control or mitigate these localized short-term high exposures to contaminants. To improve miners’ health and safety, the National Institute for Occupational Safety and Health (NIOSH) Spokane Mining Research Division (SMRD) is developing a Smart Monitoring and Control (SMAC) system for real-time monitoring of mine air quality, with integrated countermeasures to reduce these high concentrations of airborne contaminants in localized sections of mines. To develop and test a SMAC system that could be implemented in an underground mine, researchers at SMRD built a test apparatus incorporating a fan, louver, ducting, and sensors combined with atmospheric monitoring and control software. This system will institute effective countermeasures to reduce contaminant levels, improving miner safety and health. INTRODUCTION Underground metal/nonmetal mines continue to expand production by employing large equipment in greater numbers and by mining into hotter and more challenging environments which are typically further away from fresh air sources. This challenges the ventilation system to provide adequate quantities of fresh air to the workplace and increases the potential for air contamination that could result in immediate and long-term health and safety issues to miners. Currently, airflow and contaminant concentration in mines are typically based on full-shift sampling which may not identify repeated short-term exposures to high levels of airborne contaminants such as NO2, CO, diesel particulate matter (DPM), and dust with high silica contents. Repeated short-term exposure to these high levels of airborne contaminants over long periods can lead to serious health issues which are documented in several studies [1-3]. Based on data from ventilation surveys and contaminant measurements, mines often attempt to minimize exposures by sending more fresh air to the working areas where contaminant concentrations are found to be high. Real-time monitoring and control allows mines the option to monitor contaminants and implement controls in real-time. Real-time monitoring and control of the underground mine atmosphere has been a subject of research since its beginning in Finland at Outokumpu’s Pyhäsalmi Mine in 1969 [4]. More recently, the real-time monitoring and control problem has been addressed using ventilation on demand (VOD) systems [5, 6]. A VOD system attempts to deal with this issue on a global level by controlling fans, louvers, and doors to increase airflow to active work areas and reduce contamination. However, a VOD system only controls the distribution of airflow and may not be helpful in mines where the airflow is at maximum capacity. Researchers at SMRD are developing a SMAC system for real-time monitoring of mine air quality with an integrated ability to trigger countermeasures to reduce high concentrations of airborne contaminants in localized sections of mines. The SMAC system will be designed, tested, and refined in the laboratory environment before being demonstrated in an underground mine. This system will not only try to minimize the gaseous contaminants by regulating the airflow locally, but will also potentially employ a filtration system to reduce the airborne contaminants in case the maximum airflow capacity is reached. This paper presents development of the test apparatus for the SMAC system."

Jan 1, 2017

By Maribeth Amyot, Y. J. Wang, S. S. Peng

Introduction The impact of computers on individuals and businesses increases each day. And the mining industry is no exception. The growing number of short courses, symposia, and feature articles in journals on the subject of computers is indicative of the developments and interest in their application to mining. Given this interest and the growing importance of computers, a legitimate concern is the computing background of graduating mining engineers. Based on a sample survey, this paper presents the current status of computer education in Accreditation Board for Engineering Technology (ABET)-accredited mining engineering programs in the US. Specific topics addressed include hardware and software available to students, integration of computers into curricula, concerns of mining educators, and historical and anticipated trends in computing education. Methodology Nine of the 19 ABET accredited mining engineering schools (as published in the SME-AIME Guide to Minerals Schools) were surveyed. Interviews consisting of open-ended questions were conducted with a knowledgeable faculty member from each of these schools. This was done to obtain an overall view of computing in mining engineering programs. The intent was not to evaluate nor compare individual schools, so a complete census was deemed unnecessary. The minimal deviations between the responses to the subjective questions reinforces the credibility of the sample as being representative. Results Hardware Most of the mining engineering schools polled had access to hardware on three scales - mainframe computers available university wide, minicomputers available in the college or department, and microcomputers available at all three levels. Without exception, each school had access to mainframe and microcomputers. Minicomputers, however, were not available at every school. The mainframe computers have been in place the longest. The predominant mainframe currently on campuses is the IBM model. Mainframes were once the essence of all applications. But the improved availability and capabilities of smaller machines have afforded users a viable alternative. The increasing practice in education of assessing charges for time used on the mainframe - as opposed to no charge for time on the mini- and microcomputers - makes use of the smaller machines attractive. Conversely, much of the mining engineering software is only operational on mainframes. Sometimes this restriction exists because the requisite speed or storage inherent in the software can only be met by the mainframe. More often, however, it is because the software was developed when mainframes were the only machines available, and it has not yet been adapted to run on a smaller machine. At the schools polled, many mining engineering problems that are well suited to microcomputers are being solved on mainframes simply because microcomputer software is not available. Minicomputers are available at the department or college level in many mining programs. DEC is the most popular make. Often, the minicomputers were installed to alleviate the inconveniences of attempting to access and use an overcrowded mainframe, to avoid being charged for time used on the mainframe, and to meet the needs of a specific research project. The minicomputers are currently used much more for research than for teaching applications. Therefore, minis are seldom used by undergraduate students. Microcomputers have become extremely popular at mining schools within the last five years. Generally, some form of computing policy or strategy was established near the time the first microcomputers were purchased. This was formulated in part to ensure consistency, or at least compatibility, in the type of machines acquired. Microcomputers were subsequently selected based on the established computing policies; ma-

Jan 7, 1985

By E. Topuz, Xing Wu

INTRODUCTION The air flow in the mine ventilation network can be categorized in three ways: natural splitting, controlled splitting, and semi-controlled splitting. In natural splitting, the air flow in branches of a ventilation network apportions itself according to the aerodynamic resistance of the branches. In controlled splitting, a prescribed quantity of air is circulated through each branch. In semi-controlled splitting, flow in some branches is fixed to a desired quantity while in other branches it is split naturally. In practice, the mine ventilation networks present the latter two situations. Usually, the resistance of each branch in the network is known and the quantity of air in the working place is predetermined by safety considerations. If the number of branches whose airflow quantities are known is equal to or larger than the number of the fundamental meshes in the network, then the network becomes a controlled splitting network (Wang, 1982 a). Otherwise, it is a semi-controlled splitting network. If no booster fans are used in the network, the problem can be solved as either controlled or semi-controlled splitting networks in order to determine the main fan pressure and regulator size and location. All techniques are based on Kirchoff's flow and energy conservation laws and Atkinson's Equation. Booster fans can be used in controlled and semi-controlled splitting networks. It has been proven both theoretically and practically that using booster fans in these ventilation systems can improve flow distribution and reduce consumption of power (McPherson et al., 1985). The current techniques used in determination of booster fan location and size include simulation, linear programming, CPM and cutset operation, out-of-kilter, and critical-path crashing. These techniques can be classified into two groups. The first group, including linear programming, CPM and cutset operation, out-of-kilter, and critical-path crashing techniques, deals with controlled flow networks. The second, simulation, can be applied to the handling of semi-controlled flow networks. Mathematically, the problem of controlled splitting networks can be solved more easily than that of semi-controlled splitting networks. This is because the controlled flow network can be formulated as a linear programming problem, for the solution of which there are several sophisticated algorithms. Moreover, the semi-controlled flow network is usually modeled through nonlinear programming, for which there are no universally applicable solutions. The procedure described by Wu and Topuz, 1986, can be used to convert a semi-controlled network to a controlled flow network, and the problem can then be easily solved by the techniques used for solution of a controlled flow network problem. In practice, a mine ventilation network may change from controlled splitting to semicontrolled splitting with advancement of mining. This dynamic nature of mine ventilation makes the problem more complicated and necessitates development of new solution procedures which will consider the overall economics of the system. CONTROLLED SPLITTING NETWORK The problem in controlled splitting networks with booster fans is to determine the operational characteristic of the main fans, and the location and size of booster fans and regulators. The objective is to satisfy the air flow rate requirement for each branch while minimizing consumption of energy. The techniques used for the controlled splitting network problem include linear programming, CPM and cutset operation, out-of-kilter, and critical-path crashing. The objective function and constraints can be expressed as follows (Wang and Pana, 1971): [ ]

Jan 1, 1989

By Weixiang Meng, Zhao Song, Ming Guo, Zhigao Liu, Shoubao Zhang

"There are many multi-layer coal reserves in China which account for nearly 20 to 25% of the existing proven reserves. When the coals are mined in a descending order using the fully mechanized long wall mining method, they usually have roof collapse with cavity and air leak in roadways and long wall stopes; this is especially relevant when the thickness of the rock between two coals is less than 5.0 m, as the roof stability of lower seam would be greatly reduced. At the Wuhushan Mine, such abnormal strata behavior occurs, including abnormal support stress, irregular period roof pressure, and roof falls in the face. The main reasons for these behaviors include smaller roof thickness, lower rock strength, and mining influence of upper coal; these reasons were determined by analyzing the in situ conditions. A mechanics-based model of the mine geometry was set up to study the sources of stress, the stress evolution of coal, and the discriminant method of roof stability; to obtain the smallest safe thickness of roof between two coal layers, numerical modeling was applied to analyze the relations between the roof thickness and its displacement distribution. Based on the above research, the No.1001 face was divided into easy roof caving zone (ERCZ), roof caving transition zone (RCTZ), and unlikely to roof caving zone (URCZ). In the ERCZ, comprehensive grouting to reinforce the roof was implemented; in the RCTZ, local grouting to reinforce the roof was implemented. Furthermore, a face stability control index and its range were developed in a fully mechanized face combined with mine pressure observation. After implementing this strategy, there have been no unexpected roof caving or other serious strata behaviors.INTRODUCTIONChina is the country with the largest coal production in the world, and the conditions for its coal seams are particularly complicated. For example, in China’s Datong, Wuda, Pingdingshan, and Qinshui mining areas, there are a large number of multi-layer coal seams. The thickness of these coal seams ranges from 1.3 m to more than 10 m, and the spacing between layers is from under 1.0 m to over 30 m. A common problem with these coal seams is that one layer of mining has a large impact on other coal seams, which are customarily referred to as close-distance coal seams. According to statistics, close-distance coal seams account for about 20–25% and 15–18% of China’s coal reserves and production, respectively.From the reference research of Huang (1999, 2002, 2018) and Tu (2010, 2011) we can learn that in the mining process of close-distance coal seams, downward mining is mainly used. When the upper-layer coal is mined, it has a huge mining disturbance effect on the floor (that is, the roof of the lower coal). The mining disturbance increases the mining fissure in the rockmass and weakens the strata strength. The mining problem formed by this issue is that when the lower coal is mined, problems such as difficulty in roadway support, collapse of stope roof, and difficulty in ventilation are often encountered. Especially for the mining of medium-thick coal seam groups with a layer spacing of less than 5.0 m, there has been a large-scale roof collapse accident with a fall height of more than 10.0 m. In response to such problems, domestic and foreign scholars and engineers such as Tan, Zhao, and Xiao (2010), Xie et al. (2017), and others have also carried out targeted theoretical and practical research."

Jan 1, 2019

By J. A. Organiscak

Water spray applications are one of the principal means of controlling airborne respirable dust in coal mines. Since many coals are hydrophobic and not easily wetted by water, wetting agents can be added to the spray water in an effort to improve coal wetting and assist with dust capture. In order to study wetting agent effects on coal dust capture, laboratory experiments were conducted with three wetting agents used by the coal industry on -325 mesh sized Pocahontas No. 3 coal dust. Significant differences in coal dust sink times were observed among the three wetting agents at water mixture concentrations of 0.05%, 0.1% and 0.2%. The best wetting agent as identified by the coal dust sink test was only tested at the lowest 0.05% water mixture concentration and was found to have a negligible effect on spray airborne dust capture. Water spray airborne dust capture results for all three wetting agents tested at a 0.2% water mixture concentration showed that all three wetting agents exhibit similar but small improvements in dust capture efficiency as compared with water. These results indicate that the coal dust sink test may not be a good predictor for the capture of airborne dust. Additional research is needed to examine if the coal dust sink test is a better predictor of wetting agent dust suppression effects during cutting, loading, conveying and dumping of coal products by comparison to airborne dust capture from sprays.

Jan 1, 2013

By John E. Riddell

This review is based on a questionnaire sent out to 24 Canadian exploration companies, known to be active in the mineral exploration field, concerning their practice in the use of applied geochemical techniques in Precambrian terrains. Of the companies questioned, 16 returned completed questionnaires and of these, ten companies stated that they had some experience in this type of work. Of the companies who did not answer or return the questionnaire in time I know that at least three have been quite heavily engaged in applied geochemical work in the glaciated Precambrian areas. I also know that these three companies have been reasonably successful in their ventures, so I feel the following figures and opinions are, if anything, on the pessimistic side. Before continuing with the paper I would like to express my personal thanks to the Chief Geologists, Geologists and Exploration Managers of the various companies who cooperated in making this review possible by answering the questionnaires and making available summaries of their work in the glaciated terrains. Of the companies who stated that they had no experience in geochemical prospecting in glaciated Precambrian areas it is interesting to note that only two have reported that they do not use applied geochemistry at all. Two companies have reported that they make use of applied geochemistry in New Brunswick in areas of-light glaciation. Their opinion is that it is a useful aid to other techniques in evaluating mineralized areas.

Jan 1, 1960

By Ben E. Lusk

First of all let me say what a genuine pleasure it is to be here. Acapulco certainly is a beautiful change. I'm going to spend sometime talking about change, because frankly I'm astounded at the rate of change in our world today. One good example of this, reminds me that the first time I spoke before the AIME two years ago, we were at the Ramada Inn in Beckley, West Virginia. Today we're at the Princess Hotel in Acapulco, Mexico. Now that's what I call a change. Seriously though, I'm sure you've all heard it said that the most consistent thing about our society is its constant change. Five years ago, no one could have predicted the changes we experienced in the United States during the first half of the 1970's. In the past twenty-four months alone, we have seen two presidents, three vice-presidents and hundreds of administration and government personnel changes. We have stumbled from one social crisis to another, while suffering through rising inflation, major energy shortages and labor unrest that could plunge us into a full scale economic depression. In view of these constant and unpredictable changes around us, it's obvious that we must learn to deal with change and "roll with the punches" if we are to survive. A controversial book published recently, explores in detail the various aspects of change and its impact on man.

Jan 1, 1974

By W. J. Schlitt, K. McNaughton

A heap-leach field test was conducted during the 1993-1994 winter season at Carmacks, Yukon Territory, Canada. The purpose of the test was to demonstrate the viability of heap leaching Carmacks oxide copper ore in an arctic setting on a year-round basis. The test itself utilized a 5-m-diam crib loaded with 250 t of composite ore from the Carmacks copper deposit. The ore was stacked to a total height of 7 m in the crib, including 1 m of ore as an over- layer above the emitter system. This matched the plan for the commercial heap at the time when the test was started. The design also replicated an interior segment of the commercial heap. Leaching was done at a flow rate of 0.2 L/min/m2 using leachate at 21 °C. This temperature was maintained with no external heat input other than normal process heat transferred from electrowinning to the leachate via solvent extraction. Winter conditions were quite typical of those expected at the mine site. The temperature reached -54°C, while averaging -13°C over a three-month period. In spite of some flow system problems, leaching continued unabated, and freezing was limited to the insulating ore over-layer and isolated points near the outer crib walls. Thus, the test demonstrated that year-round heap leaching of Carmacks copper ore is practical in an arctic setting.

Jan 1, 2000

By Keith S. Olsen

Any discussion of barite mining is virtually impossible without considering, almost in the same breath, the many other variables, such as beneficiation, transportation, infrastructure and location that impact the economics of a particular barite orebody. My comments will be limited to just the mining aspects of barite orebodies and these observations must be considered in proper context with all other parameters affecting exploitation of a barite property prior to final decision on economic feasibility. In many instances low-cost mining situations are more than offset by high-cost beneficiation requirements. Likewise, there are cases of relatively high-cost mining associated with no or low-cost beneficiation requirements thus permitting economic exploitation. Barite orebodies and occurrences are almost as varied as the number of occurrences. As in most mining situations, the design of a mine plan and implementation of a proper exploitation program must be approached on a case by case basis. Proper and sufficient geologic control of a barite orebody must precede the development of a mine plan. Generally speaking, barite orebodies can and, at many times, do "strange" things; pinch with depth; almost never increase in size with depth, overturn, fault-off, change grade, etc. Due to the extreme variable nature of most barite orebodies, a mine plan and its implementation must be as flexible as possible. The ability to quickly adapt to variable conditions will greatly enhance the economics within a particular barite mining environment.

Jan 1, 1980

By Larry F. Barrett

Anaconda exploration in the Rico mining, district from 1978 through early 1983 resulted in discovery and partial definition of the Silver Creek molybdenum deposit. Approximately 44 million tons of 0.31% Mo are drill-indicated, and projections suggest that the deposit exceeds 200 million tons. No source intrusion has been intersected by drilling, but its composition is suggested by silicic alkali-alaskite porphyry dikes of intramineral age observed at the surface and in drill holes. Age data and fluid inclusion studies indicate that the deposit was formed 5.2 ±2 m.y. ago and that more than 1,200 meters of cover has since been removed by erosion. Both emplacement of the hypothesized source intrusion, and the geometry of the molybdenum deposit, were influenced by three major intersecting faults. The most significant of these, the Last Chance fault, juxtaposes Precambrian quartzite and greenstone against Pennsylvanian clastic and calcareous sediments within the mineralized zone. Wallrock alteration associated with the deposit is characterized by potassic, phyllic, and propylitic zones in non-calcareous rocks, and garnet and anhydrite-diopside zones in the carbonates. All +0.2% Mo mineralization is within the potassic and garnet zones. Pre-mineral faults that intersect the deposit contain the only surficial molybdenum, tungsten, and fluorine anomalies. Pervasive dispersion haloes of the indicator elements were intersected at depth by drilling in the discovery phase of exploration, and are particularly well-developed in the hanging wall of the Last Chance fault.

Jan 1, 1985

By John D. Nelson

Unprotected uranium mill tailings impoundments can pose a significant risk to nearby inhabitants and the surrounding environment in the event of a prolonged or catastrophic release of contaminants contained in the tailings. As a result of this potential, reclamation plans for such facilities must include engineering designs to protect against disruption of the tailings and the potential release of radioactive materials. The goals for such engineering designs should be to provide overall site stability for long-term periods with no need for planned ongoing maintenance and to provide a repository for the tailings that will not place a burden on future generations. Although the goal is to provide a maintenance-free system that does not require monitoring, it must be recognized that some period of surveillance would be reasonable. The surveillance period could be relatively short and only needs to assure with reasonable confidence that the reclamation scheme that was implemented is functioning adequately. An investigation was conducted by Nelson, Volpe, Wardwell, Schumm and Staub (1983) entitled Design Considerations for Long-Term Stabilization of Uranium Mill Tailings Impoundments (NUREG/CR-3397). This report assesses the degree of confidence with which long-term reclamation plans can be expected to remain effective over specific periods of time, and to assess the additional effort required to extend the design period from one long-term period to a longer one. This paper presents a summary of that investigation and discusses some of the important conclusions.

Jan 1, 1984

By T. V. Falkie

REMARKS OF DR. THOMAS V. FALKIE, DIRECTOR, BUREAU OF MINES, U.S. DEPARTMENT OF THE INTERIOR, BEFORE THE FALL MEETING OF THE SOCIETY OF MINING ENGINEERS, AIME, ACAPULCO, MEXICO, SEPTEMBER 23, 1974 This is a time of uncertainty on the world mineral scene. For some of the world's so-called "developed" countries, reserves and production of key minerals are running low. And, we have learned that the energy so essential in recovering and processing minerals can suddenly be in short supply. The prospects for a "no growth" situation in energy or mineral consumption are practically nil. Moreover, the world's economy is in flux, casting doubt on whether traditional mineral customers will continue to be able to buy, or for that matter, whether traditional suppliers of minerals will continue to sell. It is clear that the mineral situation is contributing to world inflationary pressures, which incidentally are most damaging to developing countries. So it is appropriate that SME members devote this session to the world mineral situation, and consider some of the opportunities and responsibilities that we will inevitably encounter as the future becomes the present. The opportunities, to me at least, are especially intriguing, I have the good fortune to be part of an organization that has an enormous capability and responsibility for dealing with mineral problems. The Interior Department's Bureaus, including the Bureau of Mines, have been around for a long time. They are. a prolific and reliable source of both mineral information and mineral technology.

Jan 1, 1974

By Wenbing Guo, Mingjie Guo, Hebing Zhang

As resources are depleted in coal mines, isolated support pillars are often mined. Cemented paste backfill has been used to provide support during the mining of these pillars due to its safe and green mining characteristics. However, traditional cemented paste backfill mining has some shortcomings, such as poor adaptability to geological structure, leakage of paste during filling, imperfect roof-contact in partially backfilled areas, and insufficient roof strata support before the backfill reaches its design strength. This paper presents the results of a case study where L-shaped interval cemented paste backfill technology has been safely used to mine an isolated coal panel beneath existing surface structures. This backfilling method has the advantages of preventing paste leakage, improving the backfilled ratio, reducing surface subsidence, and strongly adapting to geological structure. During this field application, the setting pressure of the backfill shield reached 20 MPa, the compressive strength of the backfilling body reached 2.0 MPa, and the backfilled ratio reached 93.7%. Observational ground monitoring showed that roof-to-floor convergence in adjacent roadways ranged from 132 to 167 mm. No obvious fractures or separations in the overlying strata were observed by a borescope. The maximum surface subsidence was 342 mm, the subsidence factor was 0.136, and the damage to surface buildings was within Grade I (slight damage). This case study clearly demonstrates that the L-shaped interval cemented paste backfill method can be safely used to mine the isolated coal panel beneath surface buildings.

Jul 1, 2023

By John E. Wallace

A recent study by the New York Trap Rock Corporation has conclusively determined that the number of blasting complaints is directly related to the noise produced by the blast. In turn it has been known for some years that the noise produced by the blast is directly related to atmospheric structure of temperature, wind, and humidity in the vertical direction. Normally during daylight hours the temperature decreases with altitude at the rate of about five and one half degrees per thousand feet on a sunny day, and to somewhat lesser amounts on cloudy days. Consequently, sound travels slower with altitude because of the lower temperature, and the sound rays tend to bend skyward, and are soon dispersed in the atmosphere. Quite frequently, however, the temperature increases with altitude, and just the opposite effect is attained. That is sound rays are bent downward, and sometimes reach the ground with intensities approaching that at the source. When the temperature increases with altitude a temperature inversion is said to exist. Less frequently than these two atmospheric conditions a condition is observed where temperature remains constant with altitude. This is called an isothermal atmospheric condition, and sound passing through this type of atmosphere tends to travel in straight lines, neither bending upward nor downward. The sound will be greater than normal near the blast, but will dissipate rapidly with distance from the blast site with no zone or zones of silence.

Jan 1, 1962

By Edgel P. Stambaugh

Oxides are important for use in the production of metals, ceramic hardware, paints, permanent magnets, magnetic recording tapes and many other uses. In some of these applications, particle morphology, degree of crystallinity, purity, and homogeneity are relatively insignificant, while for other uses, these same properties are of critical importance. Many conventional processes are based upon recovery of the oxides from aqueous solutions by processes which include neutralization, evaporation of solvent, and precipitation of a complex salt. Consequently, many of these techniques lead to oxides of low quality. There is a growing demand for oxides of high quality, i.e., materials with narrow particle size distribution, controlled particle morphology, high purity, few structural defects, and high degree of crystallinity and homogeneity. This demand has prompted industry to search for new approaches for the manufacture of these special materials. One new approach for preparing high quality oxides is hydrothermal precipitation. This process has been used for preparing simple oxides such as ZrO2; mixed oxides such as ZrO2-SiO2; and complex oxides such as BaTiO3. These oxides were prepared in a high state of purity with a high degree of crystallinity and., in many cases, without the addition of precipitants. Many impurities- that are normally precipitated by conventional methods such as neutralization present no problem since they remain in solution. Nature of the process and its applications are discussed in this article.

Jan 1, 1977

By Donald Babbitt

In 1971, during the planning and design stages of a $300 million expansion, the Iron Ore Company of Canada Ltd. through its Engineers, Canadian Bechtel Ltd., came out with a preliminary request for two (2) 10,000 LTPH belt conveyor scale systems. These Systems were to provide weighing accuracies within 2.5% of the iron ore pellets and concentrates in transit on two (2) 72" wide conveyors from the stockpiles to the ships. Each conveyor system would be fed by a rail mounted bucket wheel reclaimer, with the conveyed material moving directly to the ship loaders with no inter- mediate surge and/or storage bins between the stockpiles and the ships. The bucket wheel reclaimer discharge rates would vary from 0-9600 LTPH in cyclic periods, with the periods varying from 1-5 minutes - dependent on the level of the reclaim buckets in relation to the stockpile as well as the slewing rate of the reclaimer. There would be frequent interruptions for bucket wheel repositioning (laterally and vertically), changing ship holds, and trimming ship holds. These frequent zero flow conditions, approximately 500 per 150,000 ton ship, could last 1-5 minutes. In addition, the conveyors on which the scales were to be mounted would be over the water and subject to the wind and cold of Northern Quebec. These Systems would be in use 350 working days of the year and would load 30,000,000 LT/yr. (An average of 90,000/working day).

Jan 1, 1975

By J. G. Groppo

Froth flotation has been shown to be an effective method for reducing Loss-on-Ignition (LOI) of ponded or landfilled fly ash. Reduction of LOI is required for many fly ashes, particularly those produced from low-No, burners, in order to meet ASTM requirements for use as a mineral admixture in Portland cement concrete. An additional ASTM requirement, fineness, is critical in determining end use applicability, and in many cases, classification of fly ash is necessary to produce an acceptable product. Hydraulic classification has been shown to be a simple, cost-effective method for classification of a variety of minerals including silica, phosphate, mica, coal, etc. and has shown to be similarly effective on fly ash. The combination of froth flotation and hydraulic classification facilitate the production of a high quality pozzolan that meets or exceeds ASTM specifications. This combination has been rigorously evaluated and results of pilot-scale testing are presented. Pilot scale testing was conducted on fly ash from two active utility storage ponds and demonstrated that high quality, consistent pozzolan could be produced using APT's Fast Float? Technology. Along with the pozzolan, additional production of aggregate for masonry mortar and a low sulfur, medium Btu fuel were also demonstrated. The Fast Float? process incorporates several simple unit processes to ensure pozzolan consistency; classification controls particle size distribution which is critical to achieving early strength, flotation controls the grade with respect to L.O.I. (Loss on Ignition) while dewatering controls the moisture content.

Jan 1, 1998

By James D. Piper

In the summer of 1957,9 the University of California sponsored a World Conference on Prestressed Concrete in San Francisco to which were invited a number of Soviet engineers. While attending the conference, these engineers in turn asked the University to form a delegation of American engineers to visit the Soviet Union the following year for the purpose of studying Soviet advances in concrete technology. A six man delegation was formed, and the dates of the Russian tour fixed for May 10th through May 21st, 1958. Before arriving in the Soviet Union, the American Delegation attended the Third International Congress on Prestressed Concrete in Berlin. While there, we noticed that the delegation from the U. S. S. R. used displays and showed motion pictures of many construction projects which we later were shown in Moscow. Our delegation left East Berlin by Russian aircraft on May 11th, and arrived in Moscow that afternoon. We were met by our Russian engineer hosts from The Academy of Construction' and Architecture who made all subsequent arrangements for our itinerary. This Academy has no counterpart in the United States. It. does 40 per cent of all engineering-and scientific work in the building construction field and coordinates 60 per cent of that done by other Soviet agencies. Due to the prestige of the Academy in Russian affairs, our delegation was able to obtain a surprisingly broad picture of construction activities in Moscow and Leningrad in just ten days time

Jan 1, 1960