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By F. H. Buttner

Commodity currency intrigues most of us because of the problems it offers to solve for the Third and the First Worlds. What problems might be solved, if commodity currency were to be adopted in the Third World? That is really the question we are probing here right now. It would take a while to think through all their subtle consequences of this question, but, off the top, it might well have at least three important impacts. Most important of these to this audience is relief from unfair Third World competition. Second, it might well liberate Third World economies from financial indebtedness to the First World and give them freedom from the liquidity limitations. The third benefit is that it might help relieve World trade tensions. All three benefits are interrelated. We could start our speculations on the application of commodity currency from anyone of these starting points. But let us use the starting point most important to you, unfair competition to the U.S. mining industry. From there we might wind up with some thoughts on things you, yourselves, can do to improve things.

Jan 1, 1978

By E. G. Kelly

This paper describes the performance of a modern compound trough profile spiral that is optimized for fine coal cleaning. Reduced performance (Tromp) curves are presented to compare these new spirals with older designs, as well as with other commonly used coal cleaning equipment. As an aid to equipment selection and circuit design, data are also presented to show how variables, such as flow rate, pulp density, and particle size affect efficiency and the separation specific gravity.

Jan 1, 1984

By L. A. Romo, J. A. Ferrer

INTRODUCTION The principle line of the Caracas Metro is located generally along the most important east-west traffic corridor of the city from the yards and shops in Propatria at the western extremity to Petare, and eventually beyond to Palo Verde at the eastern end, a route distance of 21 kilometers. There will be 23 stations along the alignment, underground, at grade and elevated, and the line is forecast to handle 1,209,100 passengers daily by the year 2000 with a travel time of 29 minutes between Propatria and Petare. This principle line was divided into three sections for design purposes: Propatria-Fuerzas Armadas, Section I, Fuerzas Armadas-Chacaito, Section II and Chacaito-Petare, Section III. These sections were further subdivided into subsections for construction purposes. The Venezuelan Government, through its Caracas Metro Office in the Ministry of Public Works, awarded design contracts in sections to PARSONS BRINCKERHOFF-TUDOR-BECHTEL for Propatria-Fuerzas Armadas, Section I, OCOIDESA-GRID-APM for Fuerzas Armadas-Chacaito, Section II and OCOIDESA GRID-APM for Chacaito-Petare, Section III. Construction contracts were awarded by international bidding and work is now underway, by joint venture organizations of Venezuelan and foreign firms. The first two sections are under the administration of a company of Engineer/Inspectors in each section. The construction supervision of contracts in the first section is under the administration of the Venezuelan firm, Gómez-Celis-Herrera, (GCH) Engineers, acting under contract to the new C.A. Metro de Caracas that replaced ' the former Office of the Metro. The Propatria-Fuerzas Armadas section, approximately seven kilometers long, consists in part of the 2,951 linear meters of twin-bore

Jan 1, 1979

By J. C. Draper

This subject was introduced last April in a paper presented in Birmingham, Alabama, by James E. Elkin, General Superintendent of Duquesne's Coal Department. This paper will cover some of the same data and in addition it will update and further describe our experience. Our Portal No. 3 was started in June 1965 with battery tractor-trailer face haulage. This mine is operating in the Sewickley seam in Dunkard Township, Greene County, in Southwestern Pennsylvania as shown on Fig. 1. The Warwick group of mines fronts on the Monongahela River and extends westward for some ten miles as shown on Fig. 2.

Jan 1, 1968

By T. R. Ellis

Considerable movement is afoot internationally to rationalize standards and regulations relating to valuations and the qualifications for valuation professionals. In July 2000 the International Valuation Standards Committee released expanded standards, and additional important improvements are planned by 2003. Possible updates to the International Accounting Standards (IAS) and potential adoption of IAS by the United States could significantly impact minerals appraisers. Standards designed specifically for mineral asset valuation are under development in Canada and the United States, with Australia's internationally respected VALMIN Code providing the benchmark. In the United States, the all-encompassing Uniform Standards of Professional Appraisal Practice (USPAP) is annually modified and continues to gain deeper acceptance, while the SEC holds fast to its 1981 rule prohibiting reporting of a quantitative estimate and value for non-reserve mineralization. Some important international trade agreements are driving actions to free the trade in professional services. In July 2000, an international workshop was held to initiate discussion on minimum qualifications for appraisers to work internationally. Pressure for uniform minimum qualifications and rules for professionals internationally will continue to build. The United States is historically among the slowest countries to implement such initiatives, with its state level licensure barriers having the potential to cause some of its professionals to be stranded in an international backwater. Structural change is needed in Australia's VALMIN Code to remove conflict with the latest International Valuation Standards. The mineral valuation standards developers of Australia, Canada and the United States should work jointly on updating VALMIN for global use.

Jan 1, 2003

By Ravindra M. Chhatre

Uranium associated with phosphate deposits has been the subject of numerous investigations (1-8). In the land-pebble phosphate deposits of central Florida, uranium is found in the phosphate matrix (ore) and in the leached zone between the over-burden and matrix (1). Between 0.01 to 0.02 percent uranium is found in the leached zone, which consists of apatite and aluminum phosphate minerals (crandallite, wavellite, millisite) (Z). The primary phosphate mineral in the matrix is apatite, and the 0.005 to 0.01 percent uranium typically found in the matrix is associated with this mineral (1). It is generally believed that uranium substitutes for calcium in the apatite structure (3-5). Clay and quartz phases associated with phosphate deposits contain little uranium (1, 6), and no descrete uranium minerals have been detected in these deposits (4). A typical phosphate matrix consists of quartz, slimes (-150 mesh material) and recoverable phosphate. When the matrix is beneficiated, partition of uranium and radium takes place (9, 10). Although considerable data exists on how uranium is distributed in the phosphate deposits, no systematic study has recently been reported on the distribution of uranium during phosphate rock beneficiation. The purpose of this study was to determine how uranium is distributed in the various strata which comprise the overall land-pebble phosphate deposits, as well as how the uranium is redistributed during beneficiation of phosphate matrix. To obtain this information studies were carried out on matrix samples obtained from three different mines in central Florida. Using pilot-plant scale beneficiation, an analysis was performed on how uranium in the matrix is distributed among the pebble fractions, flotation concentrates, flotation tails, and slimes. The uranium level profile for an active mining area was also obtained. Also, since thousands of acres of slime ponds may someday become a source of both phosphate and uranium, a depth versus uranium content profile was determined for an inactive slime pond.

Jan 1, 1978

By AMIT SHARMA, BIBHUTI BHUSAN MANDAL

Operators of mining vehicles are exposed to high levels of whole-body vibration (WBV) and are therefore at risk of developing vibration-related health disorders. For implementing an effective control strategy, it is imperative to locate the source(s) of vibration, and the specific changes that might occur to the vibration signals during its transmission through the seats to the recipient human body. With this objective, Seat Effective Amplitude Transmissibility (SEAT) values of seat modules used in dumpers (n = 10) and other heavy earth-moving machines (n = 11) were evaluated in an iron ore mine. Vibration was measured simultaneously on the seat and on the cabin floor beneath the seat using tri-axial and uni-axial accelerometers. The study aims at determining the quality of seat modules of the transport and non-transport vehicles from the perspective of their natural resonance frequencies and capability of any such seat in reducing harmful vibration. The highest acceleration values were observed in the z-axis for all the dumpers. SEATrms values ranged from 78 to 133% and SEATvdv values ranged from 72 to 130% for the dumpers. For other HEMMs, SEATrms values ranged from 55 to 125% and SEATvdv values ranged from 56 to 123%. Mechanical vibration contains multiple frequency components. To understand the changes taking place to the different signals at these frequencies, 1/3 octave band analysis was carried out for the signals recorded both on the seat and the floor. There was significant attenuation (38 to 57%) at 4 Hz for three Dumper seats, whereas they resonated in the range of 1.6–2.5 Hz. The transmissibility(%) in the resonating frequencies ranged from 108 to 156%. Resonance frequencies for the remaining seven dumpers ranged from 3 to 8 Hz. The spine has been reported to resonate at 4 Hz, whereas resonance at 1.6 Hz has little significance to human beings in regard to WBV of a seated person. Hence, the characteristic resonant frequency of 4 Hz of seats as observed in the present study has the potential of causing adverse impacts on spinal health. Evaluation of SEAT factors and resonance characteristics of seats are therefore recommended to be examined while selecting a mining vehicle for regular deployment in mines.

Mar 12, 2021

By R. Raitani

Five kaolin crudes from the state of Georgia in the U.S. were investigated for processability with chemically enhanced magnetic separation (CEMS) technologies developed by Cytec. The technologies used magnetic reagent alone or in conjunction with specialty chemicals to selectively agglomerate and magnetize the desired minerals (impurities) to be removed by the conventional magnetic separation equipment. All crudes indicated treatability using CEMS. Results indicated that CEMS technology could be applied to different kaolin crudes to obtain a product with titanium impurities less than 0.6% TiO2 from individual crudes. The features and benefits of the technologies were also reviewed.

Feb 1, 2012

By J. G. Groppo

Eastern U.S. oil shale contains approximately 10 to 12 gallons of oil per ton and 7 to 10 percent pyritic sulfur. Physical beneficiation of these low grade shales using froth flotation provides a high grade material which will make extraction of oil more economically attractive. The Alabama oil shale used in the present study contained 16.46 percent organic carbon and 14.5 gallons of oil per ton as determined by Fischer assay. Liberation size of the kerogen was estimated at 10 /-Lm. 'Ken-Flote' column flotation technology provided a high grade concentrate containing as much as 60 percent organic carbon, however, carbon recovery was about 60 percent. Carbon recovery was improved to 75-85 percent while maintaining concentrate grades in excess of 40 percent carbon by providing longer retention time in the column which facilitated effective bubble-particle collision and attachment.

Jan 1, 1993

By Donald M. Hausen

Microscopic evaluation of trace quantities of metalliferous phases in flotation products requires counting large numbers of particles. Particle counts of many thousands may be required for precision, but not obtained practically by conventional microscopic techniques. A less tedious microscopic method for evaluating trace sulfides in mill tailings was developed for the O'okiep Mining Company in South Africa. Hundreds of thousands of particles were evaluated by this method called "gross-counting." Gross-counting consists of counting microscopic fields rather than point-counting individual particles. Total counts are calculated by multiplying the average number of particles per field by the total number of fields examined over the entire mount. Total gross-counts range from about 20,000 particles for +200 to 100,000 or more for -400 mesh size material in lucite mounts. Sulfides and metallic particles in each field are identified and tallied along with field counts. Totals for each type of metallic particle are divided by the total gross-count to give volume percent which is corrected to weight percent by specific gravity factors.

Jan 1, 1969

By Nathaniel White, Todd Kilduff, Justin Laviolette, Dan Laviolette, Randy Zeigler, Sean Sundermann

The Mitchell Point tunnel is a part of several ongoing efforts to connect the 12-mile-long Historic Columbia River trail between Mitchell Point Outlook to Mitchell Point Drive. The tunnel lies inside the Mitchell Spur entablature basalt geologic feature, extending 647 linear feet utilizing a typical horseshoe section with a height of 14.5 feet. The Oregon Department of Transportation (ODOT) required proper vibration control to minimize potential impacts to Interstate 84 and Union Pacific rail immediately below the tunnel excavations and sensitive, rare plants. The method of designing the vibration monitoring program and the results of its implementation show the iterative process of using monitoring to improve blast design as excavation proceeds, such as reducing air overpressure and COVID-related supply chain-constraints.

Dec 1, 2022

By Duluth Engineers' Club, Engineers' Club of Northern Minnesota

"Prospecting and Exploration. Since the Lake Superior ores occur in pockets or distinct bodies and vary much as to character and location, the actual mining of the ores is preceded by much work of an exploratory character. This work includes prospecting and exploration.Prospecting is the term generally applied to the quest for surface indications of ore, or the conditions which would warrant the expectation of finding ore in the vicinity. It includes such 'operations as geological examination, dip needle work, shallow test-pitting, and trenching. The ore bodies of the Mesabi Range are non-magnetic, and dip needle prospecting is therefore valueless. On the Cuyuna range, however, magnetic attraction as evidenced by the dip needle has been extensively employed as a guide to the location of ore deposits; in other localities it has found limited application.Drill Exploration. After the presence of an ore deposit is known or suspected, resort is generally had to exploration by means of diamond or churn drills. On the old ranges geological conditions generally make this manner of ascertaining the exact limits of an ore deposit impracticable; so, if two or three adjacent drill holes develop considerable depths of ore, the sinking of a shaft for underground exploration, development and mining is generally considered warranted. On the Mesabi Range, however, the flat-lying and comparatively shallow characteristics of the ore formation warrant much more extensive drill explorations. On this range, then, an ore body 'is almost invariably followed· out with the drills, and its limits are determined to the point where the complete plan of development can be worked out in advance of actual mining operations"

Jan 1, 1920

By Thomas M. Larimer

Prior to April, 1961, the coal charge to Clairtonts coke oven batteries was 3" x 0" mine waslied coal having approximately 6.0% to 7.0% moisture. Even at this size and moisture content, the arching, rat-holing and hang-up was excessive and the effective live storage of coal was only 60% to 70% of the rated capacity of the coal bunkers, depending upon the moisture of the coal. In addition, many production delays were encountered in the time and methods required to fill the larry cars. The need for an improved metallurgical coke led to the introduction of pulverized coal to a portion of the plant in 196 1. When the full potential of the pulverizing equipment was realized, we were able to serve seven batteries in our second unit of batteries with pulverized coal through two coal bunkers. The discharge hoppers of these bunkers were equipped with air vibrators to assist the flow of pulverized coal into the larry cars. The vibrators were helpful in this respect but required considerable maintenance and caused damage to the bin plates.

Jan 1, 1968

By P. Schumacher, M. Fein

"INTRODUCTION Newmont’s Twin Creeks operation, part of its Nevada operations, produces gold from two large open pit mines. Mined ore is processed at one of three on-site facilities: a refractory mill with two autoclaves, an oxide mill and heap leaching facilities. Twin Creeks also processes various off-site sourced concentrates and ore including high grade underground ore from the Turquoise Ridge joint venture with Barrick Gold Corporation. This paper discusses Twin Creeks’ strategic mine planning process which is part of an in-depth continuous improvement program called “Full Potential.” The process involves cost analysis, phase design validations, life-of-mine production scheduling optimization, mill blending strategy and stockpile management. Through this Full Potential strategic planning, Twin Creeks is creating significant value by increasing near term free cash flow and life of mine net present value (“NPV”) and achieving cost reductions. TWIN CREEKS OPERATION Twin Creeks is one of the major gold producers in Newmont’s Nevada operations (see Figure 1, 2 and 3). Located approximately 15 miles north of Golconda, Twin Creeks produced approximately 28 % of the Nevada operation’s 2013 gold production of 1.8 million ounces (Newmont 2014). The production included Turquoise Ridge sourced gold ore from the joint venture (75% Barrick Gold Corporation, 25% Newmont).At Twin Creeks, there are two large open pits, named Mega Pit and Vista Pit (see Figure 4, 5 and 6). There are 3 to 5 phases in Mega Pit and 2 to 5 phases in Vista Pit depending on the gold price assumption. There is also an underground exploration project at the bottom of the Vista Pit. Twin Creeks produces gold from a variety of ore types requiring different processing techniques depending on economic and metallurgical characteristics. To ensure the best use of processing assets, engineering and processing groups at Twin Creeks utilize a Mixed Integer Linear Programming (“MILP”) model to guide the flow of mine sequences and material routing to various process facilities (Kawahata, Schumacher and Hufford 2013)."

Jan 1, 2015

By Rick Frechette, Greg Nelson

"The 2018 Elko Roundtable was held at the Red Lion in Elko, NV on March 15, 2018. The gracious host was once again Knight Piésold. Attendance was robust with representatives from more than 14 mining properties across Nevada representing nine corporations. Total attendance was at its highest in almost a decade. A high level of interest was also gauged by the number of companies with multiple attendees.The topic of water in mining was clearly a factor in creating the large show of interest. In terms of industry trends that are tracked annually, this topic had been absent from the list for more than 10 years (Deloitte, 2018) but was squarely planted there this year. And deservedly so. Three attending companies are signatories of the International Council on Mining and Metals (ICMM) which espouses a firm stance on water stewardship (ICMM, 2017).How’s the water?It is reported that water scarcity affects more than 40 percent of the world’s population (Deloitte, 2018). Consumption of water in the United States, based on the last detailed census, entails only 1.5 percent usage by the mining industry. The largest users are reportedly thermoelectric power and irrigation, combining for more than 75 percent of the U.S. consumption. During the prior census period, water usage at mines was up dramatically (USGS, 2014).Mine water source usage is primarily a mix of ground water and saline or fresh surface water resources. Over the previous period, saline sources experienced the greatest percentage in growth as a mine water source, nearly doubling in use. Nevada ranks second as a state nationally in mine water consumption. California is the leader, and Nevada is immediately followed by Utah and Alaska (USGS, 2014).Water rights in Nevada and the ongoing litigation at the state level, particularly over the Humboldt River basin, have elevated the concern over the supply of water and have raised the interest regarding the topic of water across the mining industry as well as within other industries.The Elko Roundtable meeting began with a safety share and introductions, and included each attendee mentioned a water problem or solution that he or she would like to discuss during the day. An interesting list of subtopics was developed from this round robin and yielded the following most common themes:• Mine pit dewatering during operation and pit wall stability.• Draindown from tailings dams and heap leach pads and dealing with this at closure.• Post closure pit lakes, pit lake water quality and associated water rights."

Dec 1, 2018

By J. Choi

For the first time, the influence of stearyl trimethyl ammonium chloride (STAC) as a collector, on the flotation behavior of lepidolite (Uljin, South Korea) was systematically examined in Denver Sub-A cells. Flotation tests were carried out by varying amount of STAC (50?200 g/ton), feed size (-65, -100, -150, and -200 mesh), and solution pH. The impeller speed of 1000 rpm, flotation time of 10 min and AF-65 (a frother) of 250 mL/ton were invariably applied. In order to complement flotation experiments, zeta potential measurements and XRD analysis were conducted. XRD results showed that the ores were mainly composed of lepidolite, muscovite, quartz, calcite and albite. In addition, zeta potential results showed that isoelectric points were about 2.5, 2.3, and 9.7 for quartz, albite, and calcite, respectively, and lepidolite was determined to be less than 2. Overall, the results of 3-stage flotation showed that Li2O grade and recovery tended to increase with increasing STAC dosage and decreasing feed size. In addition, Li2O grade increased with decreasing pH. The results were explained by the extent of the interaction between STAC and each mineral.

Feb 23, 2014

By H. Maleki

Roof falls continue to affect productivity and safety in U.S. coal mines in spite of significant increases in support utilization in recent decades. To minimize roof stability problems while controlling support effectiveness, the U.S. Bureau of Mines is conducting research on support and ground monitoring techniques. Practical implementation of this research is presented in this paper. Instruments to monitor rock mass deformation, support loads, and microseismic emissions have traditionally been used to assess roof stability. Controlled-source seismic surveys are being used as well. In this paper, measurement techniques are reviewed, and the effectiveness of deformation measurements is demonstrated. This is achieved by an analysis of deformation history from four case studies in room-and-pillar retreat mines. In spite of differences in geologic, geometric, and support conditions in these mines, roof behavior is shown to have been similar prior to failure. The rate of roof movement is suggested as a reliable indicator of roof stability.

Jan 1, 1993

By A. J. Teske

Sustainable Development is a very broad initiative in the mining industry, with major components running over the entire life of the mine. It likely commences with pre-exploration permitting and continues to post-mining final closure and possible land reuse. Most major mining corporations embrace the sustainability initiative, either out of a sense of social responsibility or out of necessity in order to continue doing business. But many may view the overall initiative as an added ?cost of doing business.? In many elements of sustainability, there clearly can be added cost ? some as simple as complying with self-imposed sustainability reporting. Fortunately, one major element of sustainable development can clearly be shown to reduce costs ? energy resource management. This paper will describe how the mining industry sustainable development effort differs from other industries, but can benefit from their experience in energy resource management. The mining industry can utilize proven methods from other industries to further their energy management efforts. In addition, many of the resources developed and employed to promote better energy resource management in non-mining industrial settings will be listed.

Jan 1, 2010

By Charles A. Beasley

Coal conversion to electricity or to substitute natural gas requires a significant quantity of natural and human resources including, in addition to the coal resource base, land, water and the construction and operating labor force. Each method of coal conversion has its advantages and disadvantages relative to conversion efficiency, preferred method of resultant energy transportation, resources consumed, and impact on the environment. Regulations which have been passed in recent years to maintain or restore the pre-project environment can add significantly to the capital and operating costs of both a conversion facility and its associated mine.

Jan 1, 1983

By Rudecindo S. Silo

[The principal characteristics of the process is that when applied in medium or in great degree it only needs unelaborated raw materials such as sodium chloride and calcium carbonate, or of medium elaboration, as sulphur which is found in large quantity in the North of Chili; however, the may be also applied to small copper plants provided that low cost sulphuric acid is available as a substitute for sulphur, that is, in. those plats of small capacity where large additional installations are not needed for the regeneration of the leaching solution. The method itself comprises 6 stages, namely: crushing, leaching, washing; of solutions, precipitation, regeneration of the leaching solution and fusion.]

Jan 1, 1965