Search Documents

By N. S. Tanious

The need to provide better mine roof support and control in longwall tailgate entries prompted the Bureau of mines to search for a replacement product for wood cribs. Their search isolated steel-fiber-reinforced concrete (SFC) as the most effective replacement. Through successful laboratory and underground mine tests, handmade SFC cribs proved to be a viable and more effective roof support system. However, to ensure wider usage, U. S. Steel Mining Co. initiated a joint development and evaluation program with Burrell Construction Company in order to mass produce SFC blocks of reasonable dimension, weight, and cost. Small specimens and full-size cribs were evaluated during this program to determine their compressive strength and post failure characteristics. After considerable testing and adjusting of various concrete mixtures, a final formulation for the SFC crib blocks was selected. That formulation permitted the construction of SFC cribs possessing a nominal crib strength of 3200 psi (22.1 x 106 Pa) and a nominal modulus of elasticity of 1.0 x 106 psi (6894.76 x 106 Pa). These SFC cribs can support from 3.5 to 14.5 times as much load as a wood crib, depending on the size of the wood crib being replaced. Both laboratory and limited mine tests, conducted by U. S. Steel Mining Co. have shown the SFC crib to be an economical and effective means of roof control.

Jan 1, 1984

By C. Ottergren

A process does not have higher capacity than what can pass through its bottleneck. Acknowledging this, and with the goal to optimize production at a minimum investment, one can use existing equipment, modify the process flow and make a few strategic capital investments. Automatic setting regulation is a technology that allows balanced crusher performance matching minute changes in feed material characteristics. The system makes it possible to utilize the crushers fully at all times. It also continuously and completely compensates for manganese liner wear.

Jan 1, 1999

By J. Schenck

Goldcorp Inc. has mining operations and exploration projects throughout Canada, the United States, Mexico, Guatemala and Honduras; as well as partnerships in Argentina and the Dominican Republic. In rural areas of developing countries it is very common to have mining operations surrounded by diverse communities consisting of people with limited, or no formal education. This is fertile ground for anti-mining NGOs to cultivate. The limited educational backgrounds of the people, coupled with a company desire to maintain a low profile can lead to a problematic lack of trust between the local communities and the mining company. As part of its commitment to environmental stewardship and sustainable development, Goldcorp has implemented various programs to build trust at these operations, as well as incorporating this policy into any new projects prior to commencement of operations. This paper is intended to describe two initiatives that have shown positive results for both the communities and the Marlin Mine.

Jan 1, 2009

By T. J. Lutz, D. S. Yantek, L. Yan, J. R. Srednicki, J. A. Yonkey, G. T. Homce

Federal regulations require the installation of refuge alternatives in underground coal mines. Of the inuse refuge alternatives, more than 95 percent are mobile refuge alternatives, with the remainder being built-in-place (BIP) refuge alternatives. Heat/humidity buildup has been one of the major concerns with mobile refuge alternatives. For BIP refuge alternatives, however, there is a lack of in-mine heat/humidity test data to determine the extent of heat and humidity buildup. To quantify heat/humidity buildup in BIP refuge alternatives, the U.S. National Institute for Occupational Safety and Health (NIOSH) performed a series of heat/humidity tests on a 60-person BIP refuge alternative with and without a borehole air supply. At various times during the year, tests were performed with cooled, heated or unconditioned borehole air to examine how various outdoor temperatures may affect the thermal conditions inside a BIP refuge alternative. The results show that the air supplied to a BIP refuge alternative may require heating or cooling, depending on the outside air temperatures and the temperature of the mine. For example, during tests with an external ambient temperature above 21 °C (70 °F) and a relative humidity of 90 percent, providing 13 °C (55 °F) dew point air at 775 scfm, which is slightly higher than the mandated flow rate of 12.5 scfm per person, kept the internal apparent temperature below the mandated 35 °C (95 °F). Results for each test case are presented.

Jan 1, 2018

By Robert S. Shoemaker

The development of a metallurgical project is a business venture rather than a technical exercise, and its real objective is to obtain the maximum return on investment consistent with the limitations imposed by company policy and the requirements of society. Demand for profits is the driving force for technical advances and naturally leads to improvements in processes, equipment and plant designs. In the mineral dressing field there have been virtually no new processes developed since the introduction of flotation, and the steady erosion of profits by inflation has been offset only by increasing equipment size. Unfortunately, in recent years, plant designers have not always utilized the largest equipment or the opportunities for functional and economic design presented by the development of larger equipment. Lower cost plants can be developed providing that unrealistic restraints arising from the prejudice of past practices are avoided. As an illustration of this premise, three different approaches were taken toward the design of a clearly delineated but hypothetical copper concentrator of 20, 000 tons per day capacity. While the same flowsheet was used in each case, designs were produced for a conventional plant, an alternate using the largest available equipment, and a third scheme utilizing large equipment and the most functional design which could be developed, including features derived from many plants in many different industries. Capital costs were developed for the three separate designs based on a location in the southwestern United States. Ancillary facilities were identical in each case and included a mine truck shop, a maintenance shop, a general office, and a nominal starter dam for tailings disposal within 5000 feet of the plant. Water supply within 1000 feet of the plant, and power furnished to the property boundary has been assumed in each case. The flowsheet of the three plants is shown in Figure 1 and represents the treatment of a typical sulfide copper ore by three- stage crushing followed by single-stage ball milling. Concentration is by flotation roughing and scavenging followed by regrinding of the concentrates and two stages of cleaning.

Jan 1, 1971

By W. D. Bachman

A study has been made of wet, autogenous grinding of disseminated copper ores, including testing of a large number of samples from Kennecott Copper Corporation's Chino mine. The efficiency with which the various samples could be ground was found to vary over an extremely wide range, even among samples taken from different locations within the same ore body. These variations in grindability can be qualitatively correlated with the composition of the rock and the fracturing and alteration that had occurred. Because of the large-scale non-homogeneity of disseminated copper ore bodies, extensive and careful testing of autogenous grinding is needed. An accurate correlation of the grinding data from various samples with the geology of the ore body and with mining plans will indicate if variations in grinding mill throughput can be avoided in practice by mixing or blending of mill feed and if, therefore, autogenous grinding can be applied successfully.

Jan 1, 1970

By Harry E. Holzschuh

The two Agrico Chemical Company self unloading Phosphate Rock barges put into service in 1976 operate at over their design carrying capacity. Each barge now carries 26,000 short ton instead of the planned 25,000 short ton at 32 foot of draft. They are in service between Agrico's Tampa, Florida Terminal and the Donaldsonville, Louisiana Fertilizer Complex, moving a total of 2,500,000 short tons each year. This was the first use of the Parascrew design for a marine application. The barges, with their 3,000 STPH unloading and matching loading rate is the vital link in this total transportation and handling system. Rock is moved from the Pierce, Florida Mines through the Tampa Big Bend Terminal, across the Gulf of Mexico, and up the Mississippi to the Agrico Faustina Phosphoric Acid Plant 30 miles below Bacon Rouge, Louisiana. The trip from the terminal to the plant is 600 miles and the turnaround time is just about six days. Seven years operating experience has proved that the system works. Fittingly, the two barges are named the "Faustina" and the "Pierce". They have a beam of 85-feet and are 495 feet long. folded depth is 43 feet, with a ballasted light draft of 19 feet and a typical loaded draft of 32 feet. There are four separated holds with the machinery room located forward of 101 hold. Each hold is 51 feet wide at the coamings with an 18 foot straight section on the side, and a 24 foot long, 600 slope sheet for a 23 foot clear reclaim width at the bottom. The Parascrew in each of the holds is 37 feet long between the bearings and is supported on a 14 inch diameter hollow shaft. The screw pitch varies and the diameter of the flights step up from l'-9" diameter to 2'-6" diameter on the discharge end. By sloping the centerline, a minimum four inch bottom clearance is maintained across the hold. Some bending of the tube does take place.

Jan 1, 1983

The Functional Performance Equation for ball milling circuits provides plant staff with a new means to improve circuit performance. However, successful execution of a plant project, with verifiable circuit processing performance improvements, requires a significant number of accompanying steps beyond the equation alone. In order to identify and articulate all these steps, a study with plant staff from two milling operations and a grinding media supplier was undertaken. ?Task analysis? of improving plant grinding performance was carried out. This analysis called for the development of a number of system components, and ultimately yielded a ?Plant Grinding Circuit Processing Performance Management/Improvement System.?

Feb 23, 2014

By D. P. Tao, J. G. Groppo, R. Killmeyer, W. W. Wen, B. K. Parekh

Economical dewatering of ultra-fine (minus 74 m) clean coal slurry produced in column flotation to a 20 percent or lower moisture level will be an important step in successful implementation of the advanced fine coal cleaning processes. The main objective of the present study was to evaluate efficiency and effectiveness of three dewatering techniques, namely, hyperbaric, vacuum and screen bowl centrifuge, in dewatering of ultra-fine (D50 ~ 25 m) clean coal slurry produced by the `Ken-Flote' columns operating at the Powell Mountain Coal Company, St. Charles, Virginia. he hyperbaric filter using 3 bar pressure and 165o cake formation angle, provided a filter cake with 23.6percent moisture with a throughput of 800 Kg/m2-h and air consumption of 868 Nm3/t (460 scfm/t). The vacuum filter with 30 percent submergence provided a filter cake with 27.8 percent moisture with a throughput of 122 Kg/m2-h. The screen bowl centrifuge provided a dewatered product containing 32.9 percent moisture at a feed rate of 450 Kg/hr, however, the solids capture was only65 percent. Addition of 1 Kg/t of a cationic surfactant provided filter cakes with 19.1 percent, 23percent, and 34 percent moisture using hyperbaric, vacuum, and centrifuge, respectively. Similarly, addition of 0.5 Kg/ton of copper chloride lowered filter cake moisture to 20.7 percent and 24.8percent, using hyperbaric and vacuum. With the centrifuge no improvement in filter cake moisture was noted. However, use of 80 Kg/ton of `orimulsion' in the centrifuge provided dewatered product containing 26 percent moisture, and the solids capture increased from 65 to 95 percent. The dewatered product appeared dry and was easily handleable.

Jan 1, 1999

By Neil H. Bostick

This research, sponsored at Stanford Research Institute by the Grand Junction Operations Office of the U.S, Atomic Energy Commission, was an outgrowth of the concern that presently-known ore reserves may be inadequate to meet the projected demands of nuclear power reactors. The original program at SRI was to design a comprehensive geological information system and use it to store and analyze the very great quantity of data needed to estimate uranium ore reserves. Study of the problem showed that it could be solved only by use of modern electronic data processing techniques, so such a comprehensive system was designed and tested. The system test was satisfactory, but input lead time and total expense were shown to be too great for the system to be practicable for the AEC under present circumstances. Thus, based on results of the earlier research, a specialized and simplified procedure for predicting approximate uranium ore reserves was devised. The prediction is based on general geology of specific area cells of the earth, in order to provide complete volume coverage; the strata in these ores are evaluated for uranium ore favorability on the basis of a few selected criteria in order to allow rapid data input. Since the bulk of U.S. reserves are in clastic host rocks only such strata are considered in this work. This paper describes the structure and some details of the resource system and how it was tested in rn area of the western United States.

Jan 1, 1969

By R. L. Virta

Ball Clay -- Four companies - H.C. Spinks Clay Co. Inc. (owned by Lhoist Group), Imerys Group (formerly Kentucky-Tennessee Clay Co.), Old Hickory Clay Co. and Unimin Corp. - mined ball clay in four states during 2010. Production, based on preliminary data, was 910 kt (1.11 million st) with an estimated value of $42.9 million. That was a 10-percent increase in tonnage from 831 kt (916 million st) with a value of $37.7 million that was produced in 2009. Tennessee was the leading producer state with 61 percent of domestic production. It was followed by Texas, Mississippi and Kentucky. About 70 percent of production was airfloat, 20 percent was crude and 10 percent was water-slurried.

Jan 1, 2011

By Jr. Raleigh

As part vi the development of the Coal Quality Expert (CQRN) --a computer program capable of predicting the impacts of coal quality on power plant performance, costs, and emissions control--several nationally important coals are being characterized to augment the coal quality database associated with the software. The project is sponsored by the U.S. Department of Energy and the Electric Power Research Institute (EPRI) under the Clean coal Technology Program. Since 1989, CQ Inc. (a subsidiary of EPRI) has characterized seven bituminous coals from Alabama, Illinois, Kentucky and Oklahoma and six sub-bituminous coals from the Powder River Basin (PRB) in Montana and Wyoming. Coals from the PRB region--being burned more frequently in Midwestern and southern power plants to reduce emissions of sulfur oxide compounds--can sometimes contain significant concentrations of potentially toxic elements. Although no limits were imposed on air toxics emissions from fossil-fuel fired utilities by the Clean Air Act Amendments of 1990, future regulations may be implemented at the conclusion of Federally-mandated emissions studies. One possible result is that any increased utilization of coals, including those from the PRB, may depend on the potential for removing toxic trace elements prior to combustion.

Jan 1, 1993

By Donald L. Everhart

The National Uranium Resource Evaluation (NURE) program since 1974 has been designed to accomplish a comprehensive coverage of the 48 conterminous States and Alaska to evaluate the total uranium resources of the USA. This resource base includes both ore reserves and potential resources. Techniques include airborne radiometric and magnetic surveys, by hydrogeochemical surveys, surface and subsurface geologic studies, and the application of improved geochemical exploration and resource assessment methods (Table 1). In brief review, the current status of each of the five basic NURE elements is as follows: In the Aerial Surveys, in the conterminous 48 states, the flying has been completed in 89 of the NTMS 10 x 2° NURE quadrangles, and is in progress in 39 more (Figure 1). Complete quadrangle data have already been open filed for 46 additional quadrangles, for a total of 174 for which data gathering is either complete or in progress. In Alaska, the flying is complete in 42 quadrangles, and quadrangle data have been open filed for 34 more, for a total of 76 (Figure 2).

Jan 1, 1979

By Steven K. Ruggieri

Increased coal production on longwalls has brought with it higher levels of dust generation. Most U.S. longwall mining operators have difficulty complying with Federal dust standards, which are stricter than European standards. Longwall operators faced with a longwall that is "out of compliance" have implemented a variety of practices designed to reduce dust levels. Mining conditions and other important variables, however, can cause fluctuations in dust levels that may overshadow the performance of a new dust control technique. This can result in the continued use of an ineffective technique or lead to the abandonment of an effective dust control technique. No single technique can keep a longwall in compliance. Maintaining compliance requires a fundamental approach to dust control -- proper application and continued use of effective dust control techniques.

Jan 1, 1983

By A. Sullivan

Success in mining demands the creative application of equipment, systems and processes to the unique needs of each mineral deposit, market and, though often overlooked, the culture of the individual business. In recent years, domestic coal mining companies have become more attentive to the contribution safety and loss control programs have on their financial results. Although most have adopted fairly conventional safety programs, some have created systems and processes tailored to their unique circumstances. While each coal mining business must consider the typical risks inherent to our industry, excellence in safety is most likely achieved when a safety program is customized to meet the needs of the individual business.

Jan 1, 2000

By George J. Hartman

The Fort Cady in situ borate-mining project involves recovering boron from a deposit more than 400 m (1,300 ft) below the surface. The resource recovery method is a new in situ mining technology that uses weak acid solution injected directly into the ore body. As the acid contacts the calcium-based ore (primarily natural colemanite), the contained borate values are digested as boric acid. This boric acid solution is then pumped to the surface by submersible pumps. A series of chemical reactions and precipitations are performed that result in the production of calcium borate. The borate values are then recovered as a finely divided solid white powder. The refined product is sold under the trade name Cadycal 100. The Fort Cady in situ borate-mining project is located about halfway between Los Angeles, CA and Las Vegas, NV in the Mohave Desert.

Jan 1, 1996

By C. Guria

A modeling, simulation and optimization study of a complex industrial fluorspar beneficiation plant (Kadipani, Gujarat, India) with fourteen/ten flotation banks is carried out to find an optimum/near-optimum circuit for the given quality of feed ore. The phenomenological flotation model developed by Mehrotra and Kapur (1974) is used for circuit optimization. Two different optimization problems are formulated and solved. The first optimization problem involves a single objective function, which uses available plant data to estimate the feed-characterizing parameters, i.e., the flotation rate constants, by minimizing the weighted sum-of-square errors between the computed and plant values. The second optimization problem involves two objective functions to obtain several simplified circuits. The number of non-linking streams and the overall recovery of the concentrate, i.e., the acid-grade product, are maximized simultaneously in this problem. The single-objective variant (SGA-II-mJG) of the binary-coded elitist non-dominated sorting genetic algorithm with the jumping gene adaptation, NSGA-II-mJG, is used for the first problem, while NAGA-II-mJG (Guria et al., 2005 a) is used for the second problem. Simplified circuits with a few split streams are proposed on the basis of the present optimization study, which enhance the recovery of the acid-grade product without affecting its quality, for a given total volume of the flotation cell-bank. Even though the optimal solutions have certain drawbacks, they suggest a meaningful direction in using an iterative fitting of parameters to such optimal circuits, followed by re-optimization. Key words: Froth flotation, Mineral processing, Industrial fluorspar beneficiation, Feed identification, Circuit/network optimization, Global optimal, Jumping gene, Genetic algorithm, Multi-objective optimization

Jan 1, 2009

By A. Rajoria

A dynamic process model for predicting the fluidized bed roasting of copper concentrates with high arsenic content is presented in this work. Mass and energy balances were performed based on roasting mechanism derived from thermodynamic data of species. The reaction rate data, obtained from pilot plant studies on major reactions, were used in tuning the kinetic parameters of the model. DEAS, a dynamic simulation package, is used in setting up the fluidized bed roaster plant model. The effect of process parameters such as concentrate feed rate, concentrate composition, airflow and cooling water rate on the temperature and conversion of roasting reactions are analyzed. The plant model captures the highly transient conditions occurring during the plant start-up, shutdown and other process perturbations. The application of this model in constructing a virtual plant environment for validating the operating procedures and operator training is presented.

Feb 23, 2014

By Richard Chojnacki

The western united States is not usually noted for the production of fluorspar; however, many significant fluorspar districts do occur in the Rocky Mountain region and constitute a resource of sizable dimension and major potential. This is particularly true within the area of the West served by the rail lines of the Union Pacific Railroad (see Figure 1). Fluorspar deposits near the Union Pacific have produced over 1.3 million tons of finished fluorspar products from 2.3 million tons of ore. Approximately 80% of this production was of acid-grade and 20% of metallurgical-grade fluorspar. Production of ceramic-grade was negligible. Through the years substantial production has come from eight mining districts. Five of these have produced metallurgical-grade and three acid-grade. The best-known fluorspar producing area in the West is the Jamestown Mining District. It was one of the first producers of fluorspar in the western United States and is estimated to have produced over 500,000 tons of finished fluorspar from over a million tons of ore. The district encompasses approximately 36 square miles in central Boulder County, Colorado, about 9 miles northwest of the City of Boulder. Although small shipments were made from the district as early as 1873 or 1874, significant sustained production was not achieved until 1940 when the General Chemical Company, now a division of the Allied Chemical company, acquired the Alice, Burlington, Chancellor,

Jan 1, 1971

By Tim O’Neil

More than 5,300 mining professionals from around the world attended the SME Annual Meeting and Exhibit, March 1-3 in Denver, CO. Seventy three technical sessions highlighted innovative technologies and applications for the development of mineral resources. And the exhibit featured 421 companies worldwide and 632 exhibit booths. The 1999 SME Annual Meeting had 10% international attendance. Professionals from outside the United States were guests at the first SME International Reception.

Jan 1, 1999