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By W. J. Schlitt, J. H. Templeton

The chemical reactions that occur within a copper-leach recovery system are discussed, and the impact on the overall acid balance is evaluated. Both oxide and sulfide mineralogy are addressed, and their effects on acid consumption, generation and solution buffering are presented. Two case studies that apply the discussed chemistry show the practicality of using a computer spreadsheet acid-balance model for the early planning and design of copper-leach systems.

Jan 1, 1998

By Michael E. Mcllwain, Lee O. Nelson, Robert D. Rogers, James H. Wolfram

Examination of the economics and environmental consequences associated with phosphate fertilizer production documents the necessity for development of innovative production technologies. Evidence of phosphate ore's susceptibility to microbial alteration indicates that it will be an ideal candidate for industrial-scale bioseparation. There are at least two applications for the biosolu- bilization technology: (1) an industrial-scale bio- process similar to the presently used wet acid process and (2) production of small prills (bio- bead) containing unprocessed rock phosphate and the biological ingredients necessary to promote phosphate solubilization. At the present stage of development, the biobead technology is the preferred application. It is an energy-efficient "green" technology that will dramatically reduce the amount of solid waste and air emissions produced by the phosphate industry.

Jan 1, 1999

By P. J. Bethell

This paper reviews current fine coal cleaning circuitry, including water washing cyclones, tabling and froth flotation. It goes on to examine possible future beneficiation based on emerging technologies. Circuits considered include those incorporating spirals, fine heavy medium cycloning, hydrosizers and column flotation.

Jan 1, 1988

By Donald D. Haas

This presentation will discuss a mine owner's evaluation to utilize a contract miner in the development and production of gold properties. I will address both the quantitative and subjective aspects of the evaluation process. The quantitative aspects include cost evaluation, capital preservation, acquisition and disposal of new and used equipment, administrative costs, recruiting and training, and organizing a staff and craft labor force. The subjective areas of this discussion include corporate philosophy, administrative concerns, contractor competence, loss of owner control, operating flexibility, financing assistance, recruiting and training program utilization and risk reduction. The evaluation of alternatives provides a system for comparing, on a cost basis, an owner/operator system vs. a system using a contract miner. The supplement provides a concept on how a contract miner may be the cost effective system to be utilized.

Jan 1, 1989

By Patrick M. James

Many in mining believe that the industry is slipping behind in public image, in public mineral education and, particularly, in mining's basic right to do business. It is critical to turn things around - to change the rules of the game soon - before mining loses any chance of recovery. In the industry's experience, there is a technique of project development and operation that can help gain ground on public opinion. Only recently has this technique had a name, and that is sustainable development. What is sustainable development? Sustainable development is broadly accepted and supported by the international business community. And significant thought and work has been devoted to the subject. Research into the topic was initially confusing because the definitions of sustainable development are written in terms the writer, and his or her constituency understands. To some, it refers to environmental protection. To others, it is about social responsibility. And to the developer, it is about economic benefit. Slowly a theme emerged from the research that seemed to be part of all the definitions. That theme has three parts. First, the development, whatever or wherever it is, must contribute economic value to the developer and the stakeholders of the development. Stakeholders in this context include employees, neighbors, residents of the surrounding area, citizens of the country, suppliers and all others affected by the development. Next, sustainable development must contribute environmental value. This means that at a very minimum it must be neutral and not cause irreparable damage. And last, and what is new for miners and most other businessmen, it must contribute real social value to the stakeholders. How to use the concept? With that three-part theme as a working definition, the mining industry must find ways to use that “the challenge is for an individual company to translate what sustainable development means for them. There is no one model..." Donald W. Gentry is president and chief executive officer of Polymet Mining and former professor emeritus of mining engineering at Colorado School of Mines. He added: "While simple to state, the concept is anything but simple to implement. Present trends indicate ... one wins the sustainable development argument by staking out the high ground early..." In other words, start using sustainable development principles at the beginning of the project. New ways of doing business The mining industry's challenge is to implement sus¬tainable development universally around the world. Paternalism as a way of doing business is dead and a new model of doing business is emerging. All types of businesses are learning to deal with the stakeholders of new developments. Mining cannot be an exception to these trends. To understand how the international mining business came to sustainable development, it is useful to look back a few years. For many North American mining engineers, there were few opportunities for foreign assignments from the 1960s to the 1980s. American companies had been asked to leave many of the Latin American countries. Africa was going through a continent-wide upheaval. The Soviet Union and China had Eastern Eu-

Jan 1, 2000

By Larry D. Patts

Section 317(e) of the Federal Coal Mine Health & Safety Act of 1969 directed the Secretary of the Interior to prepare standards under which all working places in a mine shall be illuminated by permissible' lighting while persons are working in such places. Section 317(e) further provides that such Working places shall be illuminated within 18 months after such standards are promulgated. In accordance with this section of the Act, there was published in the Federal Register for December 31,1970 a notice of proposed ru1emaking which prescribed the illumination to be provided in the working p1 aces of underground coal mines. In 1ight of written comments, suggestions, and objections to this proposed ru1emaking, the proposed standards were with-drawn and reproposed in the Federal Register for Wednesday, October 27, 1971. In light of further comments, suggestions, and objections, a public hearing was held on April 4, 1974 and standards were again reproposed and published in the Federal Register for April 1, 1976. Promulgation of the final lighting standards took place on October 1, 1976 which means that the underground coal mining industry must comply with face illumination requirements by April 1, 1978. As mentioned previously, the first proposed ru1emaking for illumination of underground coal mines was published in the Federal Register on October 27, 1971. In early 1972, Consolidation Coal Company (Consol) and the United States Bureau of Mines agreed to a cooperative study of underground face illumination; Conso1 felt that expertise in this field would become increasingly important. Conso1's initial efforts in illumination were aimed at investigati.ng practical lighting systems for underground face equipment. We were concerned with installing unobtrusive lights which provided sufficient face illumination for safety, but at the same time were readily maintainable, electrically reliable, and physically sheltered from damage.

Jan 1, 1977

By Shane Yanagisawa

The Mineral Creek Diversion Project is at the Asarco Ray Mine Complex, about128 km (80 miles) east of Phoenix, Arizona. The new tunnel will intercept the waters of Mineral Creek about 2,134 m (7,000 ft) upstream from an existing tunnel. The 5.74 m(18.83 ft) hard rock TBM will break into the old tunnel about 2,162 m (7,090 ft) in from the old portal after mining 3,888 m (12,753 ft). The TBM will mine through a series of igneous and metamorphic formations including volcanic tuff, soft volcanic ash, massive diabase, fractured quartzite, and schist. The TBM will hole through into the existing 4.88 m (16 ft) dia. horseshoe tunnel where the TBM will be disassembled and removed from the tunnel.

Jan 1, 2001

By Gene R. Block

The most economical method of reclaiming land that has been mined, whether it be in urban areas or in rural areas, is when the final configuration of the mining area is that which is required by the subsequent use. Surprisingly, there are a number of examples of this situation. In the arid southwest where water production for the expanding population is a problem, many urban sand & gravel excavation areas subsequently serve as holding basins for ground water recharge. In other areas of the county where water is not in short supply, sand and gravel excavations can be planned in such a way that subsequent land uses such as parks and homesites can be enhanced by utilizing the excavated areas as a water amenity. Reclaiming land for agriculture is another example of utilizing the excavated area for a subsequent use providing the excavated area has not been mined too deep. Other than replacing the layer of topsoil on the excavated area, the final configuration of the mining area is in many cases ready for the subsequent agricultural use.

Jan 1, 1984

By G. R. Rao, K. A. Natarajan, P. Devasia

The role of growth conditions and adhesion of Thiobacillus ferrooxidans on the leaching of chalcopyrite was investigated. Thiobacillus ferrooxidans grown on sulfur, thiosulfate and ferrous ion substrates was used in this comparative study. Growth on sulfur, a solid substrate, requires bacterial adhesion unlike that required in the presence of soluble thiosulfate and ferrous ion in a mineral-salts medium. Solid substrate-grown cells showed higher rates of leaching than those grown in liquid media. An initial lag period noticed during leaching by solution-grown cells was absent when solid substrate-grown cells were used. Such a behavior is attributed to the presence of an inducible proteinaceous cell-surface appendage on the sulfur-grown cells. This appendage aids in bacterial adhesion onto the mineral surfaces. Such an appendage is absent in solution-grown cells, as substantiated by electrophoretic measurements. The importance of bacterial adhesion and the direct mechanism in leaching by Thiobacillus ferrooxidans are demonstrated.

Jan 1, 1997

By Brian Gettinger, Jared Barber, Richard Weatherly, Shannon Dunne, Jeff Masek, Chuck Wolf, Fazle Rabbi, Jack Canfield

During Hurricane Harvey over 60% of the 39 WWTPs, including the low-lying 25 MGD Sims North WWTP, and one third of the 382 lift stations owned and operated by the City of Houston were flooded resulting in extensive facility damage, loss of service and uncontrolled release of untreated wastewater into bayous and creeks. In response, the City has embarked on an effort to improve system resiliency by consolidating at-risk facilities with a network of deep sewer tunnels. These tunnels will provide secondary benefits to the collection system of augmenting the capacity of the existing 6,000 miles of sewer mains and lowering the collection system profile in poor performing areas. Investigations on the cost to mitigate the flood damages by raising the liquid stream processes at the Sims North WWTP is estimated at nearly $450 million. Instead of spending $450 million to raise the plant, the funds will be directed to providing a more robust and resilient wastewater system for the Sims basin area of Houston. The backbone of this new system is a 4.5-mile-long, 110 inch diameter deep gravity sewer tunnel that will convert a system heavily reliant on distributed lift stations to a majority gravity system with a deep consolidated lift station at the Sims South WWTP. This will also allow the City to address the flood prone infrastructure at Sims North and consolidate its operations into a single permitted outfall for this collection system. This approach is the outcome of a team effort focused on maximizing system resiliency and sustainability for the next 100 years. By thinking outside the box, the City of Houston will not only mitigate the flooding risk at Sims North WWTP, but also solve regulatory and operational challenges throughout the sewershed and deliver a winwin on multiple levels.

Jun 13, 2021

By Nikolay M. Sirakov, Michael L. Feves, Rumen P. Mironov, Daniel R. Hack

Subsurface investigation of sand and gravel deposits has generally been limited to test pits and borings. These techniques are problematic in terms of the accuracy, usability, and cost of the final data. Innovations in the application of geophysics have been gaining acceptance in the aggregate industry, especially to determine depth to bedrock and the extent of uneconomic inclusions. This paper presents a system to optimize the processing and evaluation of electrical resistivity data. The system uses 3D separation, geometrical reconstruction, and visualization of subsurface objects.

Jan 1, 2002

By Ernest L. Ohie

In 1939 the Geological Society of America published a summary of the geology of the ore deposits of the Mississippi Valley region, This volume, edited by E. S. Bastin, contained contributions from the foremost students of the area which described theregionalgeologic setting of the various deposits as wel as the detailed geology as then known. The various ideas as to the origin of the ores were discussed with the general, though not unanimous, conclusion that the deposits were hydrothermal products, Only those deposits in the immediate Mississippi Valley area were considered without any attempt to introduce evidence from other districts generally accepted as being of the "Mississippi Valley type." Since 1939, much new information has come from extended studies of two of the important districts described in the 1939 report andimportant extensions of the known ore have been found. Likewise, concentrated geologic efforts have been fruitful in severa "Mississippi Valley type" districts - both U. S. andforeign - not treated in the 939 paper. The wealth of new field information on the structural and stratigraphic relations of this interesting ore type, coupled with the results of theoretical and laboratory studies of the past 18 years, makes desirable a review of our present knowledge and interpretation of these important deposits which for many years have yielded over 20 percent of the world's annual production of lead and zinc, together with large amounts of fluorspar and barite. No restatement of the details of the geologic evidence willbe attempted here; the interested student is referred to the papers cited. Slide No. 1 shows the distribution around the world of the deposits under consideration. A principal thesis of my remarks is that there is so much similarity in all these deposits that it seems necessary for all of them to have had a similar mode of origin, whatever that may be. Variations in the shape, size and mineralogy of the orebodies give each district some individuality, but there are enough of the "typical" characteristics present in all cases to make classification in the "Mississippi Valley type" agreeableto most geologists. Thus the overall process giving rise to the ore solutions surely was the same for all in the group. Either they all have igneous affiliations or they all do not. Acknowledgment of this kinship between deposits in the various districts offers many advantages in trying to arrive at a decision as to just what the origin may have been, for the amount of guiding and limiting evidence which must fit into the hypothesis is greatly increased over that available in any one district, To a certain extent this was recognized by the authors of Special Paper 24 in treating all of the immediate Mississippi Valley areas together; by expanding the consideration to include ore deposits of this type all over the world the changes of success, i.e., arriving at the correct answer, are improved several fold. Since most of these districts are quite simple structurally, a number of hypotheses might fit the facts in any one of them, but if the facts to be met can safely be drawn from all the districts, then the explanations which will fit all the data are much less numerous. One purpose of this paper is to call attention to the field facts that have been reported from the .various areas which seem to have an important bearing on the kind of ore fluid that was responsible for the ore and on the way it circulated.

Jan 1, 1958

By T. Schrauf, J. Scott

"INTRODUCTION Cyanide heap leaching of gold ores in areas with extremely low winter temperatures requires special considerations to prevent freezing of the leach solution. Factors that impact the solution temperature include ore temperature at the time of stacking and during operation, burial of drip irrigation lines, use of geomembrane covers, and heating of the leach solution. Thermodynamic modeling was performed to simulate expected ore and solution temperatures under different operating strategies for Kaminak Gold’s Coffee Gold project in the Yukon Territory. Mean monthly temperatures at the site ranged from a low of -22.5oC to a high of 13.6oC, while in situ ore temperatures ranged from -0.5 to about -1.5oC. The modeling results were used to optimize the operational parameters and indicated that a combination of drip line burial and heating of the leach solution during the winter months was required to maintain solution temperatures above freezing during the initial years of stacking, although as the size of the heap increased, heating was no longer necessary. MODELING OBJECTIVES The successful operation of a cyanide heap leach under extremely cold winter temperatures requires the implementation of operational strategies to prevent freezing of the leach solution and the ore within the heap. Thermodynamic modeling of the heap provides the means to quantify the effectiveness of these different operational parameters on maintaining the required operating temperatures to avoid freezing within the heap. The operational parameters that were evaluated with the model included: • Burial depth of irrigation lines to prevent freezing during the winter months; • Variation in the temperature of the applied leach solution (to simulate heating of recirculated solution); • Variation in the rate of irrigation including seasonal variations between winter and summer months; • Seasonal versus year-round stacking of ore (to simulate the impact of the initial temperature of each ore layer as it is stacked); • Seasonal versus year-round crushing and stockpiling of ore, including the option to stockpile ore on the leach pad in the winter (i.e. stack but not leach fresh ore in winter); • Start date for seasonal stacking; • Variation of the heap geometry over time (both vertical and lateral expansion) and the associated heat storage within the heap; • Use of thermal covers (gravel or geomembrane) over the ore during the winter months; and • Effect of crush size on heat loss during crushing, stockpiling and stacking."

Jan 1, 2016

By Pablo Hadzeriga

There are two places in the world where potash, trade name for potassium chloride, is economically recovered from naturally occuring brines by solar evaporation. One is at the Dead Sea and the other at Wendover, Utah. American Potash and Chemical at Trona, California recovers potash from natural brines, but uses fuel to accomplish evaporation. Under proper meteorological conditions the use of solar evaporation might be desirable from the economical standpoint. Of course, this may not be true when, if by artificial evaporation, a group of very valuable salts are recovered. This is the case of the American Potash operation at Trona. Solar evaporation has its limits. The working temperature is low. We may say, just to cover most areas of the world where solar evaporation may be practical, that it will take place between 18°C and perhaps around 45°C. In most cases the average working temperature expected will be around 25°C.

Jan 1, 1963

Since gold was first discovered in Colorado in the late 1850s' mining has been a major part of the state's economic history, according to Stanley Dempsey, chairman and chief executive officer of Denver- based Royal Gold Inc. While the mining industry has seen some lean times throughout the past century, it has always bounced back. Today, dozens of major gold companies are headquartered in the Denver area. The state's coal mines produced record amounts during 1996. And even some of Colorado's uranium mines are resuming production. Dempsey joined other speakers in addressing the state of Colorado's mining industry during the Colorado Mining Association's (CMA) National Western Mining Conference. Some 800 people attended the CMA meeting, held Feb. 2-5 in Denver. The meeting was the association's 100th since it was incorporated in 1897.

Jan 1, 1997

By Angelina Anani, Nathalie Risso, Gail Heath, Dean Riley, Nilufer Akbulut, James Werner, Víctor O. Tenorio

Implementing a Digital Twin at the San Xavier Mine Laboratory (Sahuarita, AZ), requires a network redesign with a robust architecture. The goal is to create an ecosystem in where all personnel and equipment can be monitored in real-time from the University of Arizona campus, visualizing the site in a digital terrain model. A wireless mesh will help to test robots with autonomous features. Expected outcomes include data retrieval and analytics, the evolution of communications and safety protocols, tele-operation, and an innovated approach for managing the site with new supervision challenges. A timeline with expected commissioning benchmarks is also included.

Feb 1, 2024

By C. C. Clark, S. J. Jung

Determining the correct combination of mix components and water for high-density paste backfills that have the transport and deposition properties necessary for a mining operation is a difficult task. Rheologic properties cannot be determined without conducting full-scale pumping tests, and data from existing tests tire very limited. This paper presents the findings of investigations undertaken to determine if paste-backfill rheology can be determined using existing techniques and to determine which mix and system variables have the greatest influence on transport-pressure loss. Data from laboratory-scale pumping tests were used to produce a rheologic model of flow behavior for comparison, and a statistical analysis was conducted to determine the most significant factors affecting transport-pressure loss.

Jan 1, 1996

By W. F. Hahnert, T. L. Ward, K. E. Stoll, P. A. S. Ralston

Fuzzy logic is well suited to the control of non-linear, time-varying, and/or any system for which it is difficult to obtain an exact mathematical model. To design a good fuzzy controller, a thorough understanding of the desired process behavior is required. Many papers have suggested that fuzzy controllers are robust. If they are, it is reasonable to explore whether or not they respond better than conventional controllers to errors in the feedback signal due to imperfect measurement or sensor degradation. It may be the case that simpler or less expensive sensors could be used in some processes. The research presented here relies on an integrated array of computer programs that model and simulate (1) the process to be controlled, (2) common feedback instrumentation, and (3) both fuzzy logic controllers (FLC's) and conventional controllers. Various types of feedback sensor imperfections are imposed upon the system, and the performance of the two controllers is compared. Each controller is tuned to its optimal performance in response to a setpoint change using perfect feedback measurement.

Jan 1, 1993

By Long An, Chao Wu, Yuanhui Li, Xing Sun, Shuai Xu, Changyu Jin

Stage open stope mining (SOSM) maintains the stability of excavation openings by leaving a large number of rib pillars. Affected by the strong unloading due to stage mining and the low width-to-height (w/h) ratio of the pillars remaining, large-scale destabilization disasters of rib pillars or excavation openings easily occur when the distribution of ground stress or the size of rib pillars is unreasonable. In view of these problems, a physical SOSM model test was carried out based on an underground metal mine in the city of Chifeng in China, revealing the deformation and failure characteristics of the SOSM pillar group by overloading.

Jul 1, 2023

By Yanchuan Li, Haifei Yao, Haiyan Wang

"Dust pollution is very serious in coal mining process, which is a great threat to the underground staff health and equipment and facilities safety. Coal seam water injection in mining process is an effective way to reduce coal mine dust concentration at the source. However, the effectiveness of water injection is limited in high-pressure and low-porosity coal seam. To improve the moisture content of coal seam, expand the wetting range and enhance the effect of dust reduction by water injection, the injectability and influencing factors of coal water injection are analyzed by numerical simulation method, and the sealing technology under high-pressure condition is studied. Then, according to the practical conditions of Tangkou coal mine, the parameters and process system of process system are designed, the effect of high-pressure water injection in coal seam was determined by testing water injection quantity, water increment and dust concentration. It is showed that the dust-removal rate of the high dust concentration operation such as falling coal and moving frame is 63.49% and 59.72%, the maximum dust-removal rate of multi-processes is 53%, which achieve a high level of application. The research results in this paper is of important theoretical and practical value to improve the water injection effect of high-pressure and low-porosity coal seam and improve the efficiency of dust removal in coal mining process.Introduction With the increasing of the depth and mechanization of coal mining, coal dust, the impact of ground pressure, ground temperature and other natural disasters continue to upgrade the harm degree (Wang 2011, Wu et al 2012), disaster incidents occur frequently, which seriouslythreaten the safe and efficient mining and the physical and mental health of underground staff. Coal seam water injection can effectively reduce the coal dust when coal crushing, prevent the impact of mine pressure, coal and gas outburst disasters, by increasing the thermal conductivity of coal, reduce coal temperature, and prevent spontaneous combustion of coal. In addition, coal seam water can soften the hard coal, so that speed up the recovery rate, improve coal production and efficiency (Wu et al 2008, Nie et al 2007). However, the coal seam in many mining area is with high-pressure and low-porosity feature, Coal joint cracks are not developed and relatively hard, water injection is difficult in these coal seams, then the desired disaster prevention effect cannot be achieved (Jin et al 2001, Zhao et al 2000). In this paper, the numerical simulation and field test methods are used to design the high-pressure and low-porosity coal seam water injection technology, so as to solve the difficult problem of coal dust control in high-pressure and low-porosity in deep well mining process."

Jan 1, 2017