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Development of Technology for Complex Uranium Ores Processing on the Flotation Process Basis

Sep 13, 2010

By Alfonso W. Ovalle

INTRODUCTION The block-caving mining method is one of the most economical ways existing today to extract ore from nature. It is undoubtedly the least costly of the underground systems and moreover it compares favorably to open-pit mining. In addition to its low cost characteristic, the block-caving mining method permits a great extraction volume as can be exemplified by El Teniente's output capacity of over 22 million tons of ore per year. These characteristics of block-caving give assurance that, even though it is a very old mining system, it will be a good answer to the many future large massive low ore grade deposits to come and a1 so to rep1 ace open-pi t mining as such operations get deeper with higher stripping ratios. These are the reasons that induce further study of block-caving. In this paper block-caving at El Teniente is analyzed with due consideration to the major problems that this mine will encounter. Emphasis is given to the factors influencing the mining of soft ore which accounts for most of the ore to be extracted in the next ten years. A separate paper is devoted to a major modification introduced to block-caving hard primary ore at El Teniente by means of LHD equipment extraction. DESCRIPTION OF THE PRESENT MINING Ore Production and Flow Over 62.000 tons per day of ore are extracted 359 days per year at the El Teniente Mine. The Teniente 8 train haulage level at 1.983 m takes 29.000 tons daily to the Col6n Concentrator. Two trains make the 8 km haul with 16 cars per train. Car capacity is 90 tons. The Teniente 5 train haulage level 298 m above takes 33.000 t per day to the old Sewell Concentrator. Ore is produced from three production areas in two different levels. The so called North Mine produces 42.000 tons daily from the Teniente 4 level 65 m above the Teniente 5 haulage level. The Central Mine produces 1.000 tons from the first hard rock block caved at the Te- niente 4 level. The combined 43.000 tons per day production is sent through inclined 2 m dia- meter raises to the Teniente 5 haul age level , where 33.000 tons are taken 2.5 km to the Sewell Concentrator and 9.000 tons are hauled 0.5 km to a 5 m diameter vertical ore pass which sends ore to Teniente 8. The haulage is by 7 trains, 15 gabble-bottom cars per train. Car capacity is 20 tons. The so called South Mine produces 19.000 tons per day from the Teniente 1 level 645 m above the Teniente 8 haulage level. Ore is transferred by 2 m diameter inclined raises to the Ten 1 Retram level 22 m below, where 5 trains with 20 Sandfor Day cars per train, 8 tons capacity per car, haul the ore 1.5 km to two vertical 5 m diameter ore passes which connect to Ten 8. Starting in 1982 the Central Mine will in- crease production to 6.000 tons per day. An in- dependent loop haulage system will start operat- ing at the Teniente 5 level to feed a new under- ground 1.372 mm (54 in.) gyratory crusher which will send minus 152 mm ore (9 in.) to Teniente 8. In two or three years time the North Mine will only feed the 33.000 tons to the Sewel 1 Concentrator with its old Teniente 5 haulage system. The Col6n Concentrator will be fed from the Central and South Mines. Figure 1 shows the transfer systems and ore flows. The Ore Body In plan view at the Teniente 4 level the ore body has a kidney shape 1.800 m long and between 400 to 700 m wide. The north-eastern section of the ore body was washed away by the Teniente River. At the Sub 5 Level, 125 m below Teniente 4, the mineralization completely surrounds the circular 1.000 m diameter steep-sided barren breccia pipe (Braden pipe) . The ore body rock is 73% andesite, 14% diori te, 13% dacite and 6% mineralized breccia. Most of this ore is secondary enrichment sulfides which apart from the dacite is strongly fractured being chal cocite, cove1ine , bornite and

Jan 1, 1981

By Laurent Airaud

For around ten years, electronic detonators are available for those who want to use advanced methods and to apply theories promoted by engineers and professors to reduce blast concerns or improve fragmentation and dilution. Furthermore, decision makers can verify the use of electronic detonators to drive down mining costs. Engineers and more specifically blasters are the actual users and have to be convinced of the easiness of electronic detonators. This paper deals with electronic detonators and the notion of easiness. Common feelings about the notion of easiness are discussed. Then, examples of new technologies like, automobile, photography or Information Technology are discussed to observe how they progressed throughout time with new features and sales volume. For the specific explosive initiation industry, each step of the life of an electronic detonator is dealt with concerning the easiness and a table is used to quantify this notion.

Jan 1, 2004

By Theodore Hatch

The pneumatic rock drill operates essentially as a crusher. The rock is shattered into a powder that is removed from the drill hole by the air stream introduced through the hollow drill steel. Particles thus produced vary in size from 1/4 in. or larger down to diameters too small to be revealed by the ordinary microscope. The power consumed by the drill is proportional to the new surface area of the powdered material, therefore the greater the proportion of "dost" produced, the higher the power consumption and the lower the drilling speed. A considerable amount of material ejected from the hole settles on the rock and much of this falls back as the mound builds up to be crushed further before it is removed again. The cushion of dust at the bottom of the hole reduces the effectiveness of the blow of the bit and thus lowers the rate of drilling. The unfavorable working conditions created by the dust also reduce the drilling speed by lowering the efficiency of the operator. Thus, the dust produced by rock drills constitutes a serious drawback to economical performance on all drilling operations. To the economic objections, one must add the more important objection to the health hazard created when the dust contains free silica (quartz). The silicosis problem is a familiar one in many mines, tunnels, and other underground operations as well as in quarries and other types of open rock excavation. Dust is a necessary end product of all pneumatic drilling operations. Its production cannot be eliminated although the proportion of microscopic particles can be reduced by using improved drill steel, proper methods of sharpening, more efficient drills, etc.—improvements that increase the drilling speed largely by increasing the size of the cuttings. The absolute improvement secured in this way is not great, however, and the pneumatic drill must always remain a dust-producing machine. Definite benefits do result, on the other hand, from the use of dust-control equipment that captures the dust as it emerges from the hole and conveys it to a remote point of discharge. Dust production continues, but dust dispersion into the atmosphere is prevented. The dust is removed as rapidly as it is formed, with the following results: (I) The silicosis

Jan 1, 1937

By Robb L. Swenson

Construction of foundations for the Skyway Segment of the San Francisco Oakland Bay Bridge required innovative techniques due to the mass of the structures being inserted and the unique subsurface of the Bay. Twenty of the pier structures required large sheet pile cofferdams. Eight other foundations were installed in open water without cofferdams at the deeper part of the Bay. This narrative will present the initial planning, as well as the stages of installation, for each type of foundation. The first section will discuss foundation constructability modifications made during the initial planning phases of the project. Considerable effort was expended by Caltrans, the owner, T.Y. Lin the designer, and KFM (Kiewit/FCI/Manson) the contractor in modifying the design to assure that required tolerance would be maintained during the installation of the foundations. The final section will describe the steps required for installation including: initial access dredging, installation of cofferdams, preparation required to install the footing boxes, footing box installation, foundation support pile installation, and pile to box connections.

Jan 1, 2013

By F. L. Pirkle

A heavy-mineral deposit about 1.6 kilometers (I mile) in length and averaging about three meters (10 feet) in thickness is exposed approximately130 kilometers (80 miles) east of Denver, along Interstate 70, in Elbert County, Colorado near the town of Limon. The deposit is exposed in a geomorphic feature known locally as Titanium Ridge. The dominant heavy minerals, accounting for about 70% of the total heavy mineral suite by weight, are ilmenite, garnet, and zircon. The mineralized zone appears in a series of visually interpretable facies that are stacked vertically and represent subtidal, forebeach, backbeach, washover fan, and aeolian depositional environments. These paleoenvironments are analogous to depositional environments represented by a modern heavy-mineral bearing facies tract on St. Catherines Island, Georgia. Thus, Titanium Ridge provides evidence that heavy-mineral accumulation models for late Cenozoic deposits in the Georgia and Florida coastal plains are applicable to heavy-mineral deposits of the Western Interior subsurface and, by implication, the Western Interior Seaway, extending from Mexico to the Canadian Arctic.

Jan 1, 2011

By E. Líder, J. Pavez, J. Rivera

The application of new technologies, methodologies, and the use of new products in mining operations is a practice that is becoming more common in the industry every day, added to the new challenges and restrictions found in the operation. In the city of Tierra Amarilla, the interaction between mining operations and the community presents a constant challenge given the proximity to the community and the limitations that this presents. Explosive charge mass, in conventional blasting using traditional explosives (ANFOs, packaged explosives for example) limits the explosive charge lengths (they are reduced), impacting the explosive charge productivity. To improve the productivity of explosive charge and fragmentation, the use of low-density explosives was proposed, allowing the increase of the explosive charge length, trying to maintain the vibration levels within the established limits (2mm/s), preserving the fragmentation of the rock in the required sizes. The present study shows the results obtained from the application of low-density bulk emulsion for production blasting charges using upward and downward fan drillings. During this process, 18 blasting events were carried out, of which 8 were Up-hole loading (average density of 0.75 gr/cc) and 10 with Down-Hole loading (average density of 0.95 gr/cc). In summary, a total of 110,760 tons of ore have been broken, using low density emulsion, meeting the proposed objectives such as: 33% reduction of vibrations, 12% overbreak (within the theoretical design), P80 of 11in and 4.6% in fines.

Jan 1, 2024

Please note all Proceedings of the Institute were taken verbatim by stenotypists from Hyatt & Associates of Denver and editing has been minimal. MR. MORTENSEN: On behalf of the Rocky Mountain Coal Mining Institute, I take great plea¬sure in saying good morning to you at Vail. With a few clouds in the sky, at least we won't get sunburned. We won't have to worry about our kids in the swimming pool, perhaps. It is delightful for me to have been able to have represented the Rocky Mountain Coal Mining Institute for the year 1982-1983. This has been our 71st year and this is our 79th meeting. In recognizing the attendance here, that dinner we had last night, and some of our entertainment must have gotten to some of us, or it is a little early. But I'm sure as the day goes on, and with the speakers outlined, it will be very beneficial for those who do attend. We do appreciate your attendance. I'd first like to make an introduction of our head table. Doris Finnie, she is our executive secretary. As most of you are aware, Gussie Whiteside retired as secretary. This will be the first time since the Institute started that there has not been a Whiteside present at one of our conventions. I'm sure Gussie would appreciate any calls or letters that any of you would care to make to her. Doris, I might add, has been a great help to me and all of the people who have been working on the program for the Institute this past year. There's been lots of reorganization and we are very pleased with Doris's ability to take hold from Gussie without any waves. Much credit must be given to you Doris for this and we do appreciate the help you have given us and believe me she has kept us out of trouble. Next, we have Art Neill. He is our vice president of the Institute from Montana and he also works with Western Energy Company. We appreciate the help that all of these session leaders and chairmen give to us. We have other names on the head table, but they will fill in as the morning goes on, so we won't bother you with any of those at this time. To set the stage for business, first I would like to call on Doris for a motion to approve the minutes of last year. MS. FINNIE: Thank you, Vernal. Mr. President, I suggest that the reading of the minutes be dispensed with and that the members refer to pages 9 through 80 of the Proceedings for the 78th regular meeting of RMCMI, as published MR. MORTENSEN: Thank you, Doris. Do we have a motion to so approve? MR. LINVILLE: I so move. MR. MORTENSEN: Loren Linville so approved. Do we have a second? MR. GARR: Second. MR. MORTENSEN: All in favor say aye. (Audience responded affirmatively.) MR. MORTENSEN: Those opposed? Hearing none, the motion is carried. I'm sure glad we didn't have to read those 80 pages. Is Doug Hammer in the audience? He was going to give us a list of new members of the Coal Institute and ask for your approval. But because of his absence, the names will be listed so that you can read them at a later date, I will entertain a motion that we approve the new members who have joined the Institute. Do I so have a motion? MR. BERNSTROM: I would make that motion. MR. GARR: I second. MR. MORTENSEN: Do we have any questions? All in favor¬ (Audience responded affirmatively.) MR. MORTENSEN: Any opposed? Hearing none, the motion is carried. Next, we'd like to proceeed with our Nominating committee report from the chairman, George Nugent, and the election of next year's officers. George, would you please take the stand? MR. NUGENT: Mr. President, and members of the Institute, your Nominating committee consists of five past presidents of the Rocky Mountain Coal Mining Institute. From Colorado Roy Coulson; from New Mexico, Bob Wilson; from Utah, Bob

Jan 1, 1983

The Inglewood Gold Project consists of several titles in and around the Inglewood and Wedderburn Goldfields which were purchased from Strata Mining Corporation (now Excalibur Mining Corporation). The Inglewood goldfield has a historical production of approximately 160 000 tonnes at 23 grams per tonne. The company has reopened and developed the Maxwells reef, picking up a high-grade shoot (Max Shoot) identified and worked by Goldquest et al up until 1994. Production ceased on a low gold price, rapidly reducing vein size and a requirement for further development. Greater Bendigo Gold Mines Ltd (GBM) has undertaken the development and encountered the mineralised vein in an increasing size setting with high grades and the existing mine development has access to a further shoot to the north (Max North Shoot). The Maxwells reef also contains the Woolf shoot south of the Maxwells shaft and an inferred resource of ~20 000 ounces is contained from 60 m below surface. Best intersection 2.9 m at 50 g/t. The Maxwells reef area produced approximately 20 per cent of the Inglewood goldfields production and GBM is preparing to increase its exploration efforts across the rest of the field. A processing plant has been constructed at the Maxwells mine site, which is capable of treating tailings, hard rock and alluvial material utilising gravity recovery. The existing Maxwells tailings have been excavated and treatment commenced. It is intended to produce a sand product from the tailings for resale and to reduce the storage requirements per tonne. Several large water dams constructed by Goldquest in the 1990s are being re-engineered to enable storage of significant tonnages of tailings. A level of surface and underground production is planned for 2008 and this is to be expanded into 2009 and beyond. The long-term future at Inglewood is envisaged as structural repeats at depth below the current workings and a project plan to gain deep access will be prepared on successful drilling results.

Jan 1, 2008

By A. B. C. Stothart

"IntroductionIn the past four years Ontario Mines have made great progress in the development of reliable mine conveyance safety dogs. History shows that, prior to 1945, a rope failure on a descending conveyance was usually followed by unsatisfactory safety dog operation.It is proposed in this paper to discuss briefly;The history of this development. Progressive .development of one type (E. Long).Free fall testing of safety dogs. Anti-trailing rope device.HistoryOn February 2nd., 1945, a hoisting rope broke at the Paymaster mine. The safety dogs proved ineffective and permitted the cage to crash through to the bottom of the shaft, with disastrous results.Following this accident, the Ontario Government appointed a Technical Committee to investigate The Safety of Hoisting Equipment and Hoisting Practice in Ontario Mines. This Committee consisted of Dr. C. R. Young (Chairman) and Professors T. R. Loudon, E. A. Allcut, V. G. Smith, and Lloyd M. Pidgeon. The Ontario Mining Association (at the request of the Ontario Government) also appointed a Committee consisting of Messrs. R. E. Dye, R. D. Parker, and R. L. Healy."

Jan 1, 1950

By L. D. Gent

This report reviews the current state of the art of remote control techniques for underground continuous miners. A delineation of aspects requiring additional data is presented. Also a summary and delineation are presented in overview form for the related section functions: roof control, haulage, ventilation, power supply and rock dusting. The automated remotely controlled continuous miner project is a long-range research effort. However, the program has been divided into intermediate steps resulting in incremental production increases throughout the program. Data are developed relating the impact of our proposed research and development accomplishments to potential productivity impact.

Jan 1, 1975

By E. H. Dix

All commercial aluminum contains small percentages of copper, iron, and silicon as unavoidable impurities. The purest metal obtainable commercially, special grade high purity ingot, contains a maximum of 0.50 per cent. impurities of which the usual minimum amount of copper is 0.01 per cent.; silicon, 0.12 per cent.; and iron, 0.20 per cent. This grade is too costly for most purposes. The two standard grades, Nos. 1 and 2, containing a minimum of 99.0 and 98.0 per cent. aluminum, respectively, are more generally used. Other grades of secondary aluminum often contain as high as 3 or 4 per cent. of impurities, which include 1 per cent., or more, of zinc. Specifications for high-grade aluminum-casting alloys generally allow a maximum of 1.7 per cent. for total impurities. The S. A. E. Specification No. 33, which is intended to cover alloys made from secondary aluminum ingot, gives the iron maximum as 1.5 per cent. and the maximum for silicon (including manganese and tin) as 0.75 per cent. The effect of even relatively small amounts of impurities on the physical properties of ingot aluminum is shown by the following cornparison of two lots of aluminum, which may be taken as representative of special grade and grade No. 2 ingot, respectively. AnalysEs Special Grade, Gbade No. 2, Per Cent. PeR CBnt. Copper................................. 0.01 0.32 Silicon................................. 0.12 0.32 Iron................................... 0.42 0.82 Aluminum.............................. 99.45 98.54

Jan 1, 1923

By E. H. Dix

All commercial aluminum contains small percentages of copper, iron, and silicon as unavoidable impurities. The purest metal obtainable commercially, special grade high purity ingot, contains a maximum of 0.50 per cent. impurities of which the usual minimum amount of copper is 0.01 per cent.; silicon, 0.12 per cent.; and iron, 0.20 per cent. This grade is too costly for most purposes. The two standard grades, Nos. 1 and 2, containing a minimum of 99.0 and 98.0 per cent. aluminum, respectively, are more generally used. Other grades of secondary aluminum often contain as high as 3 or 4 per cent. of impurities, which include 1 per cent., or more, of zinc. Specifications for high-grade aluminum-casting alloys generally allow a maximum of 1.7 per cent. for total impurities. The S. A. E. Specification No. 33, which is intended to cover alloys made from secondary aluminum ingot, gives the iron maximum as 1.5 per cent. and the maximum for silicon (including manganese and tin) as 0.75 per cent. The effect of even relatively small amounts of impurities on the physical properties of ingot aluminum is shown by the following cornparison of two lots of aluminum, which may be taken as representative of special grade and grade No. 2 ingot, respectively. AnalysEs Special Grade, Gbade No. 2, Per Cent. PeR CBnt. Copper................................. 0.01 0.32 Silicon................................. 0.12 0.32 Iron................................... 0.42 0.82 Aluminum.............................. 99.45 98.54

Jan 1, 1923

By B. Coupal, F. D'Hennezel

Sorption measurements show that peat moss has much stronger affinity for oil than straw, which is currently used. Microscopic studies of peat moss show a highly porous and fibrous material, and this property, associated with the phenomenon of selective absorption, had been used to absorb oil. Laboratory experiments show that peat moss absorbs up to eight times its weight of oil. Field tests have proved that peat moss can be an effective absorbent and can be used on a large scale.

Jan 1, 1972

By Thomas R. Bur

The order of identification and in same cases the magnitude of the elastic constants of an anisotropic material depends on the orientation of the cartesian coordinate axes with respect to a set of reference coordinate axes within the material; thus confusion will result unless standard orientations are used. In this paper the relationship between the cause (the internal fabric) and the effect (the elastic properties in this case) is discussed for single crystals and for polycrystalline and amorphous materials. While reference axes based on the cause are used in the IRE (Institute of Radio Engineers) standard for piezoelectric crystals) it is shown that a reference coordinate system that would be suitable and practical for all anisotropic polycrystalline and amorphous materials must be based directly on a three-dimensional expression of the effect. The conventions offered are similar to the IRE standards for piezoelectric crystals) but use the elastic coordinates of the wave surface which can be quite readily established experimentally as the reference coordinates.

Jan 1, 1969

By Longjiang Li, Mao Jiang, Zhihui Shen, Guizhou University, Yin Pan

This paper aims to study the influence and action mechanism of collector Y-89 on the flotation of auriferous pyrite. The measurement to identify adsorption quantity, IR and XPS spectrum analysis and flotation experiment made on the pure mineral were conducted. The research results show that when the dosage of MIBC is 20 mg/L, and pH of 8, the dosage of Y-89 over 60 mg/L, the pyrite recovery rate is greater than 80%.And when the dosage of Y-89is 60 mg/L, dosage of MIBC 20 mg/L, the pH in a wider range (pH=4~9), the recovery is greater than 75%. When the pH is above 10, the pyrite is depressed and its recovery rate is found to be dramatically dropping. Adsorption quantity measurement also shows that the strong alkaline conditions inhibit the adsorption of Y-89 on the surface of auriferous pyrite. IR measurement indicates that chemisorption of Y-89 occurs on the surface of auriferous pyrite. XPS spectrum analysis indicates that without adding Y-89, oxidation reaction occurs on the surface of pyrite. But when Y-89 is added, the chemical environment of Fe on the surface of pyrite has changed. Such findings indicate that with Y-89, chemisorption occurs on the surface of auriferous pyrite.

Jan 1, 2014

By B W. Atkinson, J Docherty

An Australian Working Group has been compiling a guide for operators to use in order to improve the efficacy of their routine and non-routine sampling tasks within their coal preparation process. The guide focuses on unit operations within the process, and not conveyor belts or transfer stations that are adequately covered by the existing Standard ISO 13909.Representative sampling of unit operations is generally an after-thought following plant construction, whether that be a result of oversight, or more commonly, capital cost minimisation during initial construction. Minimising capital cost by avoiding adequate sampling systems is generally a poor decision, since the result is a process that cannot be adequately measured, meaning that it cannot be adequately managed and optimised.The use of the term ‘guide’ rather than ‘standard’ is intentional. Practical means of sampling unit operations within existing plants generally relies on a compromise between sample representativity (minimisation of bias) and sampling feasibility. The guide does not endorse poor sampling practice, but instead offers practical guidance to overcome, to the extent reasonably possible, real-life limitations.When it comes to sampling any particular process, it is almost always necessary to make a professional judgement as to whether or not the proposed samples are likely to be sufficiently representative such that the sampling will be worthwhile. Such judgement needs to be exercised by personnel who understand the principles of sampling, as they apply to the stream being sampled. There are many circumstances where available methods for sampling of a particular stream will be meaningless, and in such circumstances analytical data from that sampling will only serve to propagate poor decision-making.This paper outlines the approach for the guide, the areas it covers and the approaches adopted for different types of unit operations and associated equipment configurations.CITATION:Atkinson, B W and Docherty, J, 2017. A practical guide to sampling in coal preparation plants, in Proceedings Eighth World Conference on Sampling and Blending , pp 241–246 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

By Kenneth J. Reid

The application of computers for control purposes in hydrometallurgical processes is not as well-established as in mineral processing plants. This is not only due to the comparatively new development of large-scale application of hydrometallurgy and the relatively small number of operating plants, but also due to some of the basic dynamic characteristics of hydro- metallurgical processes., Basically there is little difference in the development and application of digital control techniques in hydrometallurgical plants from those techniques widely in use throughout the chemical process industry and in nonslurry applications; particularly for those cases involving liquid streams only, the primary sensing elements are essentially the same. On-stream X-ray fluorescence analysis is a well-established method for determination of metal content in the process streams, and standard equipment is used for the measurement and control of pH, flow, density, temperature, pressure, and other variables. Nevertheless, the high proportion of corrosive slurry streams at elevated temperature and pressure poses a challenge to the instrument engineer concerned with developing long-life, reliable instrumentation. One major difference and potential problem area in developing control systems for hydro- metallurgical processes is related to the very long time constants which are common in the larger plant. In these circumstances, it is important to define the overall control objectives very carefully and be prepared to allow for considerable drift in intermediate variables. In larger projects with many control loops the general advantage of lower costs compared to conventional analog instrumentation can be confidently expected. Also in most cases, the process analysis necessary to design and specify a comprehensive computer control system and the increased operator involvement in implementing digital control systems yield additional benefits due to the increased understanding of the dynamic characteristics of the process.

Jan 1, 1979

By Graham A. Karklin

"The Echo Bay Mines silver property is located 875 air miles north of Edmonton, Alberta. The mine is on the east shore of Great Bear Lake at Port Radium which is twenty six miles south of the artic circle, in the North West Territories.HISTORYThe area was first surveyed by J. Mackintosh Bell of the Geological Survey of Canada in the early nineteen hundreds. In May 1930, Gilbert LaBine staked claims at Port Radium called ""Cobalt"" and ""Cobalt I"". What he had discovered was an extremely rich vein of pitch-blend. These claims were the birth of mining in this area. The first ore shipment of pitch-blend was hand-picked and flown out of Port Radium in 1931. LaBine's discovery of pitch-blend became of world-wide importance with the outbreak of World War II. In 1939 the splitting of the uranium atom brought this area into world focus. It is generally believed that it was ore from this area that was used in the production of the devastating bombs which were dropped on Japan.It was at Port Radium that the leaching process for uranium extraction was pioneered. The resultant methods have been modified and adopted for use around the world. The mine was originally owned by Eldorado Gold Mines Limited. Echo Bay Mines leased the property in 1964, subsequently purchased it, and have been producing silver and copper every since."

Jan 1, 1981

By Morgan Sears

The LaModel program (Heasley, 1998) is a displacement discontinuity, boundary element model (BEM) for analyzing stresses and displacements in single and multiple-seam coal mines. After the Crandall Canyon mine collapse, the need for better design guidelines for LaModel was observed and a new calibration method for deep cover pillar retreat was developed (Heasley et al., 2010). However, the scope of this initial calibration was limited to single-seam mines deeper than 750 ft. This limited application of the initial calibration method lead directly to the research presented in this paper, which attempts to define appropriate LaModel calibration guidelines for pillar design where shallow cover and/ or multiple-seam mining scenarios are encountered. As part of this research, a database of shallow cover case histories has been developed, and this database is used to help validate the shallow cover calibration method. By adding the shallow cover database to the previous deep cover database, the LaModel calibration method has now been extended to the complete range of mining depths, as well as to multiple-seam cases. With this shallow cover calibration, the utility of the LaModel program continues to increase.

Jan 1, 2013