Search Documents

By M. Misra

The coral contaminated with plutonium at Johnston Atoll UA) was subjected to gravity and flotation separation processes at the Soil Washing Laboratory (SWL) and also at the Johnston Atoll UA) site. Tests were conducted with the contaminated coral fractions referred to as the "HP-l" ( hot particles) and the "sludge". The gravity process tested was centrifugal gravity separation and the flotation processes were conventional Denver mechanical flotation and tall column flotation. Flotation tests were conducted using both fresh and sea water. Industrial fatty acid (anionic collector) was chosen as collector to make plutonium-enriched particles hydrophobic. The use of flurosilicic acid and sodium silicate made the clean coral hydrophilic. The results show that each of the processed when tested with appropriate size fraction and operating conditions resulted in passing the success criteria. It was possible to obtain more than 80% weight of the original coral as "clean sand" having activity below the JA site "soil screening level" of 13.5 pCi/gm. The field tests spiked with plutonium particles showed remarkable success. The effect of depressants, flotation medium and the coral pretreatmentis described. Finally, a flowsheet developed by the University of Nevada, Reno to treat 8000 tons of HP-l pile presently stored at JA is presented.

Jan 1, 1996

By Clyde L. Smith

Since the early 1950's exploration in the Yukon Territory, Canada, has been confined largely to Selwyn basin where at least five large stratiform or massive sulfide Pb-Zn deposits have been discovered. The five ore bodies total nearly 100 million tons of 10-16% combined Pb-Zn with 1-3 oz./ton Ag. The only deposit currently in production is the Anvil Mine operating at 8,000 tons per day. Beginning in 1972, exploration in the Mackenzie Mountains, east of Selwyn basin and west of Mackenzie arch, resulted in finds of Mississippi Valley type Zn-Pb mineralization in a belt of Proterozoic and Lower Paleozoic carbonate rocks (Figure 1). Four districts have been located and intensive exploration by numerous Canadian and Arnerican mining companies is currently in progress over a length of 400 miles in the carbonate belt. The consensus is that a major new Zn-Pb province may be taking shape.

Jan 1, 1974

By Hongjie Yu, Mike Mooney

Transitions between geological/geotechnical soil units have a critical impact on the operation and performance of a tunnel boring machine (TBM). Geostatistics-based probabilistic modeling is used to quantify the uncertainty in soil transition locations. This paper presents two unique soft-ground tunneling case studies where the results from the geostatistics-based probabilistic modeling are compared to the TBM data and as-encountered ground conditions derived from the actual TBM data. The assessment enhances the confidence in using geostatistics to improve ground awareness for efficient tunnel construction, minimizing different site condition (DSC) claims, and improving decision-making on tunnel projects.

Dec 1, 2022

By Georgene Renner, Chee Theng, William Gleason

"With more than 900 booth spaces sold and 630 exhibiting companies displaying their wares, there was something for all 7,804 attendees on the exhibit floor of the 2015 SME Annual Conference & Expo in Denver, CO Feb. 15-18. The following is a sample of what was offered at the 2015 meeting.3D Laser MappingData collection and data analysis are changing how mining is done. One field in which technological advancements have made safer and more efficient operations possible is through site and slope monitoring.3D Laser Mapping, a United Kingdom-based company, was on hand at the 2015 SME Annual Conference and Expo to display its solutions for the mining industry, including its SiteMonitor4D system.The state-of-the-art laser measurementbased system was developed in partnership with geotechnical engineers and mining surveyors, and is a simple-to-use, reliable solution that has the flexibility and performance to function in a range of monitoring applications.The system measures and monitors the stability of rock faces, landslips and man-made structures, including ongoing, periodic measurement of volumes - stockpiles, cutbacks and waste dumps and has high-speed laser scanning for regular mapping of large areas by mounting the scanner on a vehicle.With specifications that other monitoring techniques cannot achieve, laser scanning opens up a new dimension in mine measurement and monitoring.www.sitemonitorsystems.comA.R. Wilfley and Sons Inc.Founded in 1919, A.R. Wilfley and Sons Inc. has been manufacturing dynamic-seal and static-seal pumps in Colorado for nearly 100 years, delivering its high-reliability, low-maintenance, heavy-duty process pumps and slurry pumps to the global mining industry. The family-owned company is now in the hands of the fifth generation."We are the dynamic-seal experts," regional sales manager Cesar Murillo said. "Most other companies are unable to do 100 percent dynamic seals and have to use mechanical seals or packing," he said, but Wilfley’s sealing technology does away with the need for mechanical seals and packing and their associated problems. As a result, solids and slurry handling capabilities are high, the pump can be run dry, and product dilution is eliminated. The pump can tolerate more misalignment, more cavitation, and more vibration in the pump during operation."

Jan 1, 2014

By S. Deming

Coal is China's main source of energy. In 1988, 76.1% of commercial energy consumption was supplied by coal. To provide a rational utilization of its coal resources, China has paid considerable attention to coal preparation over the last 10 years. In 1980, there were only 105 washeries treating about 100 million tonnes of coal, but by 1988 there were 151 washeries treating 171 million tonnes per year. This paper describes the development of China's coal preparation industry; its growth, the equipment, and the technology. Statistics and information on the current status of the industry are also be presented.

Jan 1, 1991

By John F. Abel

Convergence measurement across the 17.4 m (57ft) high shaft station/loading pocket at Mt. Taylor provided continuing verification of stability and safety. Three levels of instrumentation, consisting of three lines each, were installed and monitored. The instrumentation showed that the flexible lining restrained the adjacent rock. The flexible lining consisted of pea gravel with neat cement between rock and liner plate, wooden crush blocks between liner plate and steel ring beams. The loading pocket is elliptical, 11.6 by 9.6 m (38 by 31 1/2 ft) I.D. The crush blocks were designed to allow 15 cm (6 in.) of convergence. Maximum predicted convergence was 7.0 cm (2 3/4 in.) and 5.7 cm (2 1/4 in.) was measured. Convergence measurements also demonstrated decreasing deformation with respect to elapsed time and distance from the measurement station to the temporary bottom of the shaft excavation.

Jan 1, 1984

The properties of interfacial water at hydrophilic surfaces are of great importance in many technological areas including flotation, solid-liquid separation, dispersion and emulsions, flocculation, adsorption, corrosion, and soil contamination. This paper examines the use of FTIR/internal reflection spectroscopy (FTIR/IRS) to study the spectral characteristics of interfacial water at silica surfaces. FTIR spectra were characterized by consideration of the OH stretching region (3000-3800 cm-1) associated with the vibrational spectra of interfacial water. The broad peak in this region was deconvoluted in order to isolate overlapping spectral features that describe the nature of hydrogen bonding in interfacial water. Three distinct bands were found; -3600 cm-1 (free OH), -3400 cm-1 (incomplete tetrahedral coordination), and -3240 cm-1 (complete tetrahedral coordination) and the variation of their intensities with pH was found to be significant. This spectral information helps to explain orientation and bond ordering of interfacial water molecules at hydrophilic surfaces.

Jan 1, 1998

By Peter T. Chiang

A brief literature review on metal separations by ion exchange and solvent extraction of their thiocyanate complexes which are practiced in analytical chemistry as well as in industries was performed. Owing to the poor stability of free thiocyanic acid in acidic aqueous and organic media, technical and environmental problems which cause high thiocyanate consumptions often arise during the practice of the separation processes. This prompted the conducting of a second and more thorough literature review on the chemistry of thiocyanic acid. The objectives of this undertaking are to compile and interpret literature data on the physical properties and chemical reactions of thiocyanic acid, thus providing a clearer understanding of the causes of these problems and giving options as to how to minimize them. The best answer found for carrying out the separation processes is to keep the temperature, thiocyanic acid concentration and total acidity as low as practical.

Jan 1, 1984

By I. Iwasaki

The effects of autogenous grinding and conventional grinding on the floatabilities of copper-nickel sulfides were investigated as a part of a pilot-plant development project on the differential flotation of Duluth gabbro. At the same mesh-of-grind copper, nickel, and cobalt recoveries were higher and residual sulfur in the flotation tailings was lower with the autogenously-ground pulps. With the ball-mill-ground pulps the residual sulfur in the tailings could not be lowered to the level attained by the autogenously-ground pulps even at increased levels of the collector addition. From mineralogical examinations of concentrate and tailings samples, an electrochemical interaction between grinding media and sulfide minerals was thought to have a greater effect on sulfide mineral flotation behavior than the breakage characteristics of the ore samples in these two types of mills.

Jan 1, 1981

By Yueyue Ding, Yuanhui Li, Zhengrong Li, Pengfei Yu, Kunmeng Li, Zhipeng Xiong

The stress evolution and failure characteristics of overburden were studied during multi-stope mining for a gently inclined thin orebody. Firstly, an indoor physical experiment was conducted on the excavation of a multi-stope mine with an orebody dip angle of 20°. The results show that the vertical stress concentration area gradually shifts to deep-buried rock mass with the mining from shallow to deep buried stopes, resulting in shear failure originating from high stress. On the contrary, the pressure relief zone presents an asymmetric distribution characteristic that is biased towards the upper part of the goaf, resulting in large subsidence and tensile failure of the stope #1 and #2 roofs. Secondly, the numerical simulation model under the same geological condition was established to measure the roof deformation at different stages of mining. The numerical simulation results are in good agreement with the physical test results; the roof displacement is largest in stope #2, second-largest in stope #1, and smallest in stope #3. Finally, the evolution of deviator stress concentration, displacement field and potential failure zone of overburden under different orebody dip angles were studied. As the dip angle of the orebody increase, the deep-buried stope roof changes from deviator stress release to deviator stress concentration in different stages of mining, and shear failure is most likely to be induced when the orebody dip angle is 30°. Meanwhile, the closure displacement of the stope roof decreases gradually, while the tangential displacement increases, so the anti-sliding ability of the support bodies in the stope should be improved. The potential tensile failure zone gradually shifts from the center of the goaf to the upper part, and the deep-buried stope roof evolves from tensile failure to shear failure. Results of this research expected to provide guiding significance for stope support design to control roof deformation and failure, to ensure the safety of the stope.

Mar 2, 2023

By James A. Decker

Hanna has developed three production planning systems to help the mine engineers determine the sequence of mining from available ore supples. The Production Scheduling System was developed to give the staff a tool for long range planning by sequencing the removal of blocks from an open pit property. It was needed to determine the year of removal for each block so that the optimum present-valued pit limits could be established by our pit design program. Since in this type of planning short term grade control is less of a factor than it is in daily or monthly planning, the system gives the program greater control and more latitude in block selection. It permits only full blocks to be taken.

Jan 1, 1984

By Behzad Khorshidi

"The ultimate objectives of the post-tensioned strands are to connect the precast segments into a ring and provide pre-stress in the tunnel circumference. The method involves inserting the strand through the preliminary embedded duct in the precast concrete segments and then tensioning the strand by jack and fastening it. The post-tensioned strand eliminates the necessity of bolt connections between the segments and may reduce the labor cost and increase speed of lining construction. Pre-stressing of the segmental lining reduces the steel reinforcement or fiber volume in precast segments and/or thickness of the precast segments which would result in reducing the manufacturing cost of them. Pre-stressing would reduce cracking and increase water tightness, and would provide smooth intrados due to eliminated bolt joints and pockets in the tunnel lining. Pre-stressing would increase resistance to internal pressures as well. Further, this system could work very well structurally in tunnels with squeezing rock or tunnels with high seismic loadings. INTRODUCTION OF THE METHODPost-tensioning is commonly used in the construction of bridges, large buildings, nuclear power stations, and water tanks but its utilization in tunnels is still in its infancy.The precast pre-stressed concrete segmental lining can be used for shield tunnels. It provides a reinforced lining ring by the following construction stages and as shown in Figure 1:1) Segments to be assembled by TBM to complete a full ring2) Steel strand to be inserted through embedded duct (sheath) within the segments3) The strand to be tensioned by Jack after anchorage of the other end4) The strand to be fastened after reaching required tension load5) The horizontal strands (if necessary) to be installed, tensioned and fastened6) The recesses and gap between strand and duct to be filled by groutingFurther, Figure 2 shows an unbonded post-tensioning strand model; Figure 3 shows an anchor sample (Xanchor); Figure 4 shows a duct (sheath) and anchor within reinforcement; Figure 5 depicts the posttensioning of a strand by jack; and Figure 6 is an image of the Midorigaoka Trunk line tunnel in Sagamihara, Japan which was constructed using this system."

Jan 1, 2016

By G. R. Addie

While the cost of transporting raw phosphate matrix from a pit to a processing plant via slurry pipelines is more efficient than it could be by rail cars, conventional trucks or belt conveyors, it still amounts to many millions of dollars, and in many areas there still exists much room for improvement. By taking advantage of pipeline test data on different slurries, it is possible to reduce costs by optimizing pipeline diameters, operating velocities and slurry concentrations. Better wearing, more efficient pump designs are now available which, if applied correctly, can lead to significant savings. The authors discuss what benefits are possible in relation to the electrical operating and wear maintenance costs and go into some of the factors associated with taking advantage of these benefits, identifying what they see as being practically possible.

Jan 1, 1998

By G. A. Shirey

Breakthroughs in software technology and in computer hardware capabilities have opened new opportunities to develop more accurate process simulators and to reduce the operating time to reasonable levels. As a result, there are several new simulation packages being commercialized for modeling coal preparation plants and pulverized coal-fired power plants, and the users of these packages are reporting significant improvements in process efficiency and operating costs by implementing the simulators' results. This paper provides an overview of some of the models currently in use at CQ Inc., including the ASPEN PLUS"" Coal Cleaning Simulator, the Ultramax® process optimization software package, and EPRI's Coal Quality Impact Model?. Case histories of specific applications are also presented.

Jan 1, 1995

By B. Berhe, R. D. Lawrence, J. Hinzer

"The fortunes of mining companies and their implied value are tied to cycles - both economic and commodity – within which they operate. Hence the determination of appropriate future metal prices is one of the most critical factors faced by mineral valuators especially for advanced projects. Price, and hence revenue, is usually the most sensitive input to the valuation model. Empirical studies of past forecasts show that the success rate for commodity price forecasting is very poor. This paper explores various approaches and comments on their strengths and weaknesses. We conclude that careful evaluation of long-term metal prices is a key element and is hardly a luxury that can be left to simple averages or rules of thumb. INTRODUCTION Discounted Cash Flow (""DCF"") analysis, is well suited for the valuation of advanced mineral development assets, for which there are identified mineral resources and some form of economic assessment (Pre-Feasibility or Feasibility Study). The DCF method is also the most commonly used method for determining value for such assets. It provides a means of relating the magnitude of expected future cash flows from profits (or losses) to the magnitude of the initial cash flow (investment) needed for capital expenditures to purchase or to develop an asset for commercial production. The method proves useful in making investment decisions as it allows for the quantification of the Net Present Value (“NPV”), as well as the Internal Rate of Return (IRR) and Payback Period on initial investment capital. Valuation by its very nature is a forward-looking exercise. The DCF method attempts to estimate the NPV of expected future cash flows, by selecting factors that will likely affect future cash flow based on informed analysis. One of the most critical and sensitive factors is the determination of appropriate future commodity prices. “The variables that have the greatest impact on a DCF evaluation are the reserves, the metal prices, and the discount rate.”1 The determination of future commodity prices for valuation purpose or during M&A negotiations is a hotly contested issue. There are a number of analysts, institutions and specialized commercial data suppliers that provide both short and long-term commodities price forecasts. Also, the use of an aggregated mean for all available forecasts, or consensus forecasted prices for valuation purposes is not uncommon. The methods used in making forecasts for each forecaster may vary and in many cases may not be publically disclosed. Nonetheless, the aggregated mean of all forecasted commodity prices of reputed institutions is usually taken to “represent the market’s view of likely future commodity prices.”"

Jan 1, 2016

By F. G. Crack

This paper is based on the philosophy that the management structure and strategy required for mine construction and development projects are different from that required for routine production and maintenance operations in a mine. The purpose of this paper is to present an integrated approach to the management of mine development projects. This paper highlights the four major aspects of the integrated approach. First, a brief review of the various types of contract documents is provided. Second, the management organization of a project is discussed. Third, the project manager's role and the field supervisor's responsibility are briefly outlined. Finally, the use of scientific techniques for planning, scheduling, executing, and controlling projects is presented. Each of these aspects is important; however, each by itself cannot be expected to bring order or unifying impact to the complexities involved in overall project management. When all these aspects are coordinated, the result will be a sore successful project from conception to completion.

Jan 1, 1982

By M. K. Gangal, E. D. Dainty

The paper describes the capabilities of a micro-computer-based real time data acquisition system for monitoring and control of mine environments. Applications of such a system for monitoring the ventilation and air quality of a mine is outlined. The paper discusses the results of running a monitoring system with various environmental sensors in a simulated mine environment. The sensors used in this study are: carbon monoxide (CO), carbon dioxide (C02), nitric oxide (NO), nitrogen dioxide (NO2), sulphur dioxide (SO2 ), methane (CH4 ), air flow, absolute pressure, temperature and relative humidity. A performance evaluation of the monitoring system and sensors is presented.

Jan 1, 1987

In 1988, at the request of members of the Society for Mining, Metallurgy, and Exploration (SME) Inc., the president of SME formed Working Party No. 79, Ore Reserve Definition. Its mission was to develop guidelines for the public reporting of exploration information, resources and reserves. These guidelines were published in the April 1991 issue of Mining Engineering,(pp. 379-384), and as a document entitled "A Guide for Reporting Exploration Information, continued on an ad-hoc basis until 1996. Working Party No. 79 was then renamed the SME Committee on Re¬sources and Reserves and became a standing committee. Since 1994, the Council of Mining and Metallurgical

Jan 1, 1999

By P. W. Conrad, C. Todd, N. West, R. Kramer

"Surface subsidence caused by both underground room-and-pillar mining operations and solution mining operations have each been studied separately, but never combined. In 2008, FMC Minerals began using solution mining at its Westvaco Mine as a secondary extraction method in an area that had been previously mined using the room-and-pillar mining method. Mining regulations require that subsidence associated with underground mining activities be monitored and measured annually. Researchers at Montana Tech were able to develop a relationship between measured surface mine subsidence and solution mining that can be used at the Westvaco Mine to estimate the production of trona from solution mining operations. PROJECT BACKGROUND FMC Minerals (FMC) has increased the production of trona from its Westvaco Mine near Green River, Wyoming, using solution mining as a secondary extraction method in an area previously mined using the room-and-pillar method. The area of interest was mined until 2001 with the use of a borer miner at a depth of approximately 1,600 feet. Currently, FMC determines the amount of trona produced using its solution mining operations by measuring the dissolved solids pumped from the mine. This approach, however, does not account for the location from which the trona was removed. The location from which the trona was removed and the size of the cavern created by the solution mining operations is important to FMC’s mine planning. FMC believed that with proper investigation of the subsidence at the Westvaco test site, a correlation might be found that would allow for the use of surface subsidence measurements to estimate the amount and location of trona production from the solution mining activities. The primary goal of this project, conducted by Montana Tech, was to find a relationship between the measured subsidence and the solution mining activities. The project attempted to model the relationship between the measured subsidence and the solution cavern using Salt_Subsid, an existing subsidence software package from the Solution Mining Research Institute (SMRI), to determine the program’s usefulness for locating and developing the cavern created by solution mining activities. The project also attempted to develop an equation that could be used to predict solution trona production based on measured subsidence. The data used in this study were collected over a seven year period, 2008 through 2014."

Jan 1, 2016

By Peter N. Yanker

The two types of dryers used in the drying of copper concentrates are the rotary dryer and the spray dryer. The rotary dryer has until recent history been the traditional drying method used, Although spray dryers have been used in the chemical field for many years it is only recently that they have been accepted for drying of copper concentrates. The comparison made here will apply in a narrower sense to the drying of copper concentrates as fed into the reverbatory furnaces of the Smelter. To compare a rotary dryer and a spray dryer, which are two totally different methods and pieces of equipment, it is best to view them as systems each made up of certain elements

Jan 1, 1976