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By J. E. Lees

Advanced remote sensing can be a powerful new information tool to help private and public entities make better environmental and resource management decisions. However, some regulated entities are reluctant to develop or use this tool because of their concerns that it will lead to increased risks and costs of environmental legal liability. They fear that new ways of monitoring the environment will increase liability, undermine existing enforcement agreements, reopen compliance agreements, and generally provide a competitive disadvantage to early adopters by accelerating environmental cleanup costs. Others counter that the increased risks are marginal, and that several advantages outweigh these risks, including the opportunity to more effectively manage environmental operations, target and set priorities, measure and track management and compliance effectiveness, provide more defensible environmental assessments and baseline conditions, make and defend optimal siting decisions, and avoid or resolve environmental disputes. This paper offers strategic advice on ways regulated entities can enjoy the benefits of these powerful new information tools while mitigating down-side legal and compliance risks as much as possible.

Jan 1, 1999

By L. Nahai

In an exchange of views with the Program Chairman for the Technical Session on Industrial Minerals and Investment in Foreign Countries, it was agreed that it would be more interesting to approach the problem of mineral investment in foreign countries in a more general framework and not confine it to industrial minerals. Therefore, this Bureau of Mines report is proposed to examine current attitudes toward investments in foreign mineral resources and restraints that they impose on investments necessary to assure supply for future global mineral needs.

Jan 1, 1976

By Y. H. Zhan

A new P(MAAA) latex was developed and used in separation of ultrafine apatite from calcite and silica by means of selective flocculation. The latex was found to flocculate selectively apatite from apatite/calcite and apatite/silica mixtures in the presence of sodium tripolyphosphate and sodium silicate over a pH range from 9.1 to 9.4. The separation of apatite from calcite was more selective with sodium tripolyphosphate, while the results of the separation of apatite from silica were better when sodium silicate was used. In the apatite/calcite system, 90% apatite recoveries into a concentrate containing 34% P2O5 were possible in the presence of 4 mg/l of sodium tripolyphosphate at a latex dosage of 2.2 kg/t. In the apatite/silica system, 80% of apatite could be recovered into a concentrate containing 33% P2O5 in the presence of 20 mg/l of sodium silicate at a latex dosage of 1.1 kg/t. Deposition tests were used to study the interaction between the latex and the mineral surfaces. The results revealed that deposition density of the latex on apatite was higher than on calcite; the differences between the deposition onto these two minerals were higher at pH 9.2 than at 7.2. The results point to the stronger interaction between the latex and apatite surface when compared with the latex-calcite interactions.

Jan 1, 1998

By C. E. Tackett

The Greenwich Collieries Co. is a subsidiary of the Pennsylvania Mines Corporation, and a wholly owned subsidiary of the PP&L Co. which serves the northeastern portion of Pa. PP&L annually consumes about 11 million tons of coal per year and is the largest consumer of both bituminous and anthracite coal on the eastern seaboard. Development work for Greenwich started in 1969. The coarse coal plant was constructed in 1970, with the raw fines bypassed. This worked very well for our requirements at that time; however, the Greenwich mining plans were extensively changed, longwall mining units were installed and low coal was encountered, resulting in dirtier coal, a finer coal and an ever increasing ash in the shipped product. All this demanded a more efficient ash removal process for the fine coal fraction. In 1971, the Pennsylvania Department of Environmental Resources and the Federal Environmental Protection Agency were pushing for the now stringent sulphur emission limits at our power plants. The Greenwich Mine coal reserves contained large quantities of 3.5 to 4% sulphur along with some low sulphur reserves. It was, therefore, essential that any new plant have the capability of efficient sulphur removal to meet the Pennsylvania Department of Environmental Resources and the Federal Environmental Protection Agency required limits. To meet these limits our design would have to be capable of producing a product of 2.0% sulphur or less.

Jan 1, 1977

By Richard C. Corson

Modern microprocessor systems make it possible to use several variables to anticipate changes in the process and to react with responses before upsets can be magnified by the process or by control action. Through tighter control, "insurance" can be eliminated from process set points without affecting product quality. In actual operation with a traveling grate furnace this control philosophy has produced savings of up to 20% in fuel consumption and 8% in fan power usage while producing a more consistent quality product.

Jan 1, 1982

By Dipl. -Ing. H. -J. Sager

The ‘Westerschelde Tunnel’ underpasses the estuary of the Schelde in the Netherlands. The tunnel will consist of two tubes which are driven by two hydroshields (slurry shields). The tunnels will each have a length of approx. 6.6km and a bore-diameter of 11.33 m. Demanding ground conditions had to be considered during the design of the shield machines. Loose sands, extensive clay formations and high ground water pressures of up to 6.5 bar will be encountered during the tunnel drive. The tunnelling activities will start in the middle of 1999 and are scheduled to end by the end of 2001.

Jan 1, 1999

By James R. Yancik

Economical and environmental pressures necessitates the recovery of the minus 0.6 mm x 0 coal generated by todays mining machines. This size fraction, dependent on the type of production unit, maintenance of the production unit, and the Hardgrove Grindability Index, can be a substantial portion of the Preparation Plant feed. Historically, dewatering of the collected 0.6 mm x 0 product has often been rather expensive and marginal with respect to surface moisture reduction. The Freeman United Crown II Preparation Plant more than adequately demonstrates that the continuous scroll type centrifuge can dewater 0.6 mm x 0 coal to acceptable surface moisture levels.

Jan 1, 1981

By D. W. Carson, R. J. Trembley

Thoron daughter WL&apos;s measured by alpha-spectroscopy and the Kusnetz method are about one-half those of radon daughter WL&apos;s in a uranium mine in Canada.1 A diffusion model can account for the relative concentrations.l Since the Kusnetz technique is most widely used for measuring radon daughter WL&apos;s in uranium mines, a general procedure is derived to extend this method to measurement of WL&apos;s of radon and thoron daughters in air containing their mixtures. Coté P. and Townsend M.G., 1981. A procedure is also suggested for counting radon and thoron daughters by 3-channel [a]-spectroscopy. Errors in WL(Rn) are calculated for standard radon daughter counting procedures when a-decay of both thoron and radon daughters is attributed to radon daughters alone. Providing overall counting times are short, [<]30 min, these errors are generally small. The precision of ß -counting methods is also investigated. A portable 3-channel alpha spectrometer for measurement of radon and thoron daughters in uranium mines or homes is described, Carson D.W., 1979. The computer programs for analyzing the data to give, depending on the mode employed, some or all of the concentrations RaA, RaB, RaC, ThB, ThC and WL of radon and thoron daughters by alpha spectrometric, modified Kusnetz, Rolle and Tsivolglov methods are presented.(l) A commercial apparatus, based on the above prototype, incorporating a microprocessor and built under contract to EMR is now available.(2) A number of personal radiation dosimeters for miners are now being tested in mines. One of these is the CEA dosimeter which uses the track-etch film method, Duport P., Chapuis A.M. and Pradel J., 1979. An apparatus for rapid reading of track-etch films by the spark technique has been described previously, Cross W.G. and Thomasino L., 1970 and Huang V.F., 1975. We have developed such an apparatus for rapid semi-automatic reading of films exposed to radiation from mixtures of radon and thoron daughters in CEA dosimeters. The films used, Kodak LR 115 Type II Strippable, may be stripped rapidly and easily, for counting after irradiation and developing, by use of a special punch and suction technique. The method promises to provide an inexpensive and rapid technique for reading large quantities of personal dosimeter films. However, the present CEA dosimeter has faults in design, leading to a contamination problem. Those films that show contamination cannot be read by automatic means. A commercial apparatus based on the above prototype spark counter and built under contract to EMR is now available.3 1. These computer programs are available on request. 2. Pylon Instruments, Ottawa 3. Bondar Clegg, Co. Ltd., Ottawa. REFERENCES Carson, D.W., 1979, "Canalph-3, a Portable Three-Channel Alpha-Spectrometer for Measuring the Daughter Products of Radon and Thoron", CANMET Division Report MRP/MSL 79-108 (TR). Coté, P. and Townsend, M.G., 1981, "Mixtures of Radon and Thoron Daughters in Underground Atmospheres", Health Physics, Vol. 40, pp 5-16. Cross, W.G. and Thomasino, L., 1970, "Rapid Reading Technique for Nuclear Particles Damage Tracks in Thin Foils", Radiation Effects, Vol. 15, pp 85-89. Duport, P., Chapuis, A.M. and Pradel, J., 1979, "Appareil Individuel pour lu Dosimetrie des Descendants du Radon", Advances in Radiation Protection Monitoring, IAEA Vienna, pp 435-443. Huang, Y.F., 1975, "Determination of Uranium in Minerals using Fission Tracks", M. Sc. Thesis, University of Toronto, 48 pp.

Jan 1, 1981

By Jack V. Hill

A unique type of grinding mill liner has been developed by Waagner-Biro A.G. of Austria. This liner system, termed an angular spiral lining (.ESL), was, successfully tested by Magma Copper Company&apos;s San Manuel concentrator in both their 10 Ft x 10 Ft (3.05m x 3.05m) and 12 Ft, 6 In x 14 Ft (3.81m x 4.27m) grate discharge wet grinding ball mills. Magma Copper&apos;s savings in power and grinding balls justified conversion of more than half of their twenty-six ball mills to the ESL system.1,2 The ASL system was provided by the Capitol Castings Division of Midland Ross Corporation, the exclusive licensee for such conversions. Capitol Castings proposed the following as expected benefits from installation of an ASL system in an 18 Ft x 21 Ft (5.49m x 6.40m) overflow discharge wet grinding ball mill at the Pinto Valley Operation of Cities Service Company: "(a) Reduction of power consumption per ton of ore milled = 12%, (b) Increased throughput = 6%, (c) Reduction of ball consumption = 6%."

Jan 1, 1982

By Stanislaw Nawrat, Waclaw Dziurzynski

An increasing concentration of coal production, especially in the circumstances of intensive methane inflow makes the coal mine managing staff apply new techniques of safe mining. It paves also the way for scientists to develop new directions of investigations and implementation of state-of -the- art technical solutions. Simultaneously, it could be noticed that the funds assigned for expansive &apos;En situ &apos; investigation are continuously decreasing. Better and better results are reached when applying computer technique in calculations of the parameters of ventilation process. Recent theoretical and experimental investigations of air and gas (methane) flow in longwall areas with caving, combined with the implementation of methane drainage system allowed to create, a mathematical model and consequently to elaborate a computer supported numerical simulation of discussed phenomena. The mathematical model has been modified and the simulation program was prepared in such a way that the software is convenient for a user looking for an optimal solution. The paper presented the methodology of optimal choice of following parameters: - ventilation system - rate of flow through the wall. The procedure takes into consideration keeping a safe level of concentration methane in air flowing through the longwall as well as the criterion of maximum methane concentration within the methane drainage pipe line. Results of variant computer simulation regarding the longwall with caving are shown in graphs and tables.

Jan 1, 1995

By Madeline Mello, Michael Low, Nick Karlin, Bryce Scofield

The LA Effluent Outfall Tunnel is the first tunnel in the United States to incorporate post- tensioning into the precast segmental lining. Several unique components were integrated to ensure that the post tensioning could be carried out successfully in the tunnel, even concurrently with the TBM excavation. This also required the development of new processes both in the casting facility and in the TBM to ensure that the almost 3,700 rings could be successfully manufactured, threaded, stressed, and grouted. This paper will discuss the material selection, fabrication, and installation of, as well as lessons learned from, this first in country tunnel lining.

Jun 23, 2024

By M. T. Ityokumbul

Experiments have been carried out to determine the efficacy of bubble column flocculation. An acid-base neutralization method was used to determine the mixing time in a 0.064 m x l.5 m bubble column equipped with a Mott porous sparger. The mixing times decreased as the tracer injection point approached the gas sparger. Preliminary flocculation experiments on two clay samples were carried out. The effects of frother addition and air flow rate are presented and discussed.

Jan 1, 1998

By William P. Lorenz

The paper describes a uranium by-product recovery plant operating within a copper leach, solvent extraction, and electrowinning circuit. The operation is unique because it is integrated into the main process stream of the copper circuit The plant processes 1408 m3/h of copper solutions containing about 10 mg/L of uranium. An Eluex type process was selected due to its compatibility with the copper leach plant. The paper includes an overview of the copper circuit

Jan 1, 1983

By S. A. Bunk, W. P. Wood

In the early 1980's BHP identified several potential gold deposits in West Africa. One of these deposits was located in Mali, near the village of Syama. As a result of extensive explo­ration activities, an oxide ore as well as an underlying sulphide ore was identified. After agreement with the government of Mali was reached the development of the deposit was undertak­en. The plan for the development of the mine included the treat­ment of the oxide ore followed by the treatment of the underly­ing transition and sulphide ore. The development of the deposit was extremely aggressive. Following the approval of the project in early 1989, engineer­ing was started, equipment purchased sitework was started, and the first ore was introduced in December of 1989. This was accomplished in spite of the difficulties of the site. These diffi­culties included: • remote site location without air or road or water access • no existing infrastructure including water, power, or communication • high health risks • limited construction and manufacturing support in West Africa The operation began with a conventional crushing/grind-ing/CIL/elution and electrowinning facility. The facility was designed to treat 2000 metric tonnes of ore per day. After start­up in December of 1989, the operation was improved to the point that plant throughput was averaging nearly 3000 tpd and running at 92 to 93% availability.

Jan 1, 1996

By T. Bui

The shut-off value for a panel cave mine determines when a draw point will be shut-off and mining will cease from that draw point. Using a shut-off value strategy for a panel cave mine is similar to using a cut-off value strategy for an open-pit mine. This paper will discuss how to choose an appropriate shut-off value strategy that an engineer can use when planning a panel cave mine to increase the net present value (NPV) of the project. Using a shut-off value equal to the mining and processing cost will provide the total mining reserves for a panel cave mine given a specified footprint. When the net present value analysis method is used to compare one design to another then using a shut-off value greater than the mining and processing cost will generate a higher NPV. This strategy will replace the marginal ore at the top of a draw column with higher grade ore at the bottom of newly opened draw points. A draw column is broken material which sits above a draw point and it is mined to a specified height above the draw point. This height is called the height of draw (HOD). Varying the shut-off value over the life of the mine can increase the NPV even further. This strategy would have a high shut-off value during the early stages of a mine and low shut-off value during the later stages. If the shut-off value is too high then too many tonnes would be left behind the draw point and the overall value of the mine will be decreased. Also with a high shut-off value then the production target may not be maintained due to too many draw points closing too soon.

Feb 23, 2014

By W. T. Robertson

My charge is to review briefly "Coal In The Electric Utility Industry - Present and Future." Thus, I will not dwell on the overall energy picture, other than to express what most others involved in the energy picture know - we&apos;re in trouble! Several years ago, speaking to another engineering society, I said, "Much has been and yet will be said and written about the energy situation in our Country." What an understatement! The energy question has reached crisis proportions and is a top priority item at the highest level of government, Unfortunately, it will be in that situation for some time to come. Many factors created this complex problem, and we all share some of the blame. But I am perplexed when I read in the popular press that environmental factors are unrelated to the energy crisis when I know this to be untrue. In the recent past all forms of energy have been cast in the role of villain, particularly coal with its problems of surface mining, mine safety, acid water drainage, sulfur content, and a multitude of other adverse factors relating to the environment in one way or another. As you know, the sulfur situation has led to the closing of numerous mines, resulting in the lessening of our mining capacity. Today, along the Eastern Seaboard, 60 to 70 million tons of coal are displaced by imported oil, primarily to meet air standards. Even in the Midwest, utilities sitting on enormous coal reserves are converting to other fuels or hauling low sulfur coal thousands of miles from the western Mountain States. [We will hear more about this coal from another speaker on the program this morning.]

Jan 1, 1973

By R. Halatchev

This paper treats the spatial aspect of mine sequence optimization, revealing it in the context of determining the optimum number of cutbacks of an openpit mine. Cutback mining is currently a dominant method in the mining of base and precious metals. It is based on a pseudo-economic discretization of the pit space using advanced pit design algorithms. The result of implementing such an approach of pit design is the generation of pit shells, which need to be grouped into an optimum number of cutbacks to maximize project value. In this paper, the development of a mathematical solution of this problem using combinatorial analysis is presented. The solution provides a multivariate investigation of the optimum mine sequence with the implementation of a method for production scheduling optimization that uses Net Present Value (NPV) as a criterion for assessing the economic efficiency of mine sequencing. A case study using the conditions of a hypothetical openpit gold mine is provided to illustrate the applicability of the approach. The results obtained reveal the complex nature of NPV variation as a function of the cutback geometry.

Jan 1, 2015

By Wenbing Guo, Mingjie Guo, Hebing Zhang

As resources are depleted in coal mines, isolated support pillars are often mined. Cemented paste backfill has been used to provide support during the mining of these pillars due to its safe and green mining characteristics. However, traditional cemented paste backfill mining has some shortcomings, such as poor adaptability to geological structure, leakage of paste during filling, imperfect roof-contact in partially backfilled areas, and insufficient roof strata support before the backfill reaches its design strength. This paper presents the results of a case study where L-shaped interval cemented paste backfill technology has been safely used to mine an isolated coal panel beneath existing surface structures. This backfilling method has the advantages of preventing paste leakage, improving the backfilled ratio, reducing surface subsidence, and strongly adapting to geological structure. During this field application, the setting pressure of the backfill shield reached 20 MPa, the compressive strength of the backfilling body reached 2.0 MPa, and the backfilled ratio reached 93.7%. Observational ground monitoring showed that roof-to-floor convergence in adjacent roadways ranged from 132 to 167 mm. No obvious fractures or separations in the overlying strata were observed by a borescope. The maximum surface subsidence was 342 mm, the subsidence factor was 0.136, and the damage to surface buildings was within Grade I (slight damage). This case study clearly demonstrates that the L-shaped interval cemented paste backfill method can be safely used to mine the isolated coal panel beneath surface buildings.

Jul 1, 2023

By A. E. Desrosiers, R. L. Kathren, D. L. Haggard, J. M. Selby

INTRODUCTION The radiological health significance of thorium-230 stems from its tendency to separate from the uranium238 parent, concentrate in bone tissues, and to subsequently irradiate the radiosensitive tissues lining the bone surfaces and the bone marrow. Indeed, thorium-230 may be the radionuclide which contributes the major dose following intake of natural uranium (Hartley and Pasternack 1979). This is reflected by the most recent recommendations of the International Commission on Radiological Protection, which specify the limits shown in Table I for the annual intake of radionuclides by occupationally exposed workers (ICRP 1979). TABLE 1. Occupational Annual Intake Limits (microcuries per year) for Selected Uranium Nuclides and Daughters (ICRP 79) [Radionuclide Ingestion Inhalation] [Uranium-238 200 0.05 Uranium-235 200 0.05 Uranium-234 200 0.03 Thorium-234 300 200 Thorium-230 3 0.02 Radium-226 2 0.5] Clearly, the relatively low annual limit of intake for thorium-230 shows it to be of greater radiological concern than its parent radionuclides. Because of the greater toxicity and different metabolism of thorium-230, monitoring only for uranium-238 does not satisfactorily identify the possible hazard from thorium-230 nor does it provide any real indication of the metabolism or biodynamics of these two radionuclides. Thorium-230 has a half-life of 80,000 years and can be detected by direct counting of the alpha particles or photons emitted during its transformation to radium-226. The 4.69 and 4.62 MeV alpha particles are distinctive and specific indicators of thorium-230 and are emitted with abundances of 76% and 24%, respectively. The principal photon, a 68 keV gamma ray, is emitted in only 0.37% of the transformations and is, therefore, not useful for low level measurements. The other photons emitted have even lower yields, or, in the case of radium L x-rays, are non-specific and, hence, useless for quantification. High sensitivity measurements of thorium-230 currently are usually accomplished by wet washing of the sample substrate, quantitative chemical separation of thorium atoms, and, finally, direct measurement of the alpha particles emitted from a massless deposition. This procedure is complicated, expensive, and time-consuming, and subject to interferences from uranium, other actinides, and other thorium isotopes. Recently, the feasibility of low-level measurement of thorium-230 by neutron activation analysis (NAA) was demonstrated (Kathren, Desrosiers and Church 1980). Two principal variations of the NAA method were used in this study: 1) instrumental NAA technique and 2) post-irradiation radiochemical separations (RCS). Instrumental NAA procedure is a nondestrucive technique which is preferred because of its simplicity. The procedure is as follows: after irradiation with a known neutron fluence, the samples are transferred to a clean container and quantitative gamma spectroscopy performed. With the radiochemical separations procedure, the sample is initially treated as in the instrumental technique. However, after irradiation, a known amount of "carrier" is added to the sample. The element(s) of interest are then separated from the rest of the matrix by distillation, precipitation and extraction techniques. The resulting sample, now free of interferring elements, is then ready for gamma-ray analysis. The use of a "carrier" is to determine the loss of element-of-interest during the chemical separations process. The neutron activation cross section of thorium-230 has an epicadmium resonance value of 1,010 barns (Mughahghab and Garber 1976) and a thermal neutron cross section of 23 barns. The 25.52 hr thorium-231 produced releases two photons of significance: an 84 keV complex, (6.5% yield) and 25.6 keV (15% yield) (Lederer and Shirley 1978). The 84 keV complex is particularly useful for quantification since neither natural uranium, thorium, their daughters, or activation products emit photons in this region. However, the higher yield of the 25.6 keV photon may result in increased sensitivity if there are no other photons of similar energy emitted by other radionuclides in the sample. PRELIMINARY STUDIES Thorium-230 standard stock solution was prepared from a pure sample of the oxide purchased from Oak Ridge National Laboratory. From this stock solution a series of samples were prepared for irradiation in the TRIGA Mark I reactor at Reed College. Various dilutions were prepared as well as thorium-230 spiked urine samples. Irradiation times varied from 1 to 54 minutes in a neutron fluence rate of 1.84 x 1012 n/ cu m-sec. The neutron spectrum was abundant in thermal neutrons, having a Cd ratio of approximately 10. Treated urine samples were also analyzed by the NAA instrumental method. Analysis of untreated urine samples was not possible due to the high background

Jan 1, 1981

By W. de Moura, R. Fueyo, M. M. Botz, J. C. Scola

The Cerro Vanguardia mine is an AngloGold Limited operation in southern Argentina that includes multiple open pits and a hybrid Merrill-Crowe and CIL circuit to recover gold and silver from oxide ore. Operations were commissioned at the site in 1998, which included a plant in the metallurgical circuit to recover cyanide from mill tailings. The cyanide recovery plant was initially configured to process tailings slurry and achieved greater than 90% cyanide recovery from tailings containing about 600 to 800 mg/L WAD cyanide (as CN). The cyanide recovery circuit was operated in this manner for approximately eight months, during which time the consumption of sulphuric acid and sodium hydroxide was relatively high, leading to high rates of scale formation in the acidification tank and stripping towers. In July 1999, several piping changes were made in the cyanide recovery system to permit its operation with clear solution, which reduced the sulphuric acid consumption and eliminated scale formation in process equipment. The cyanide recovery system currently operates with a two-stage counter-current decantation (CCD) circuit which provides clear solution for processing in the cyanide recovery plant. The cyanide recovery efficiency now averages about 90% to 92% from solution containing about 350 mg/L WAD cyanide (as CN). Recovered sodium cyanide now accounts for about two-thirds of the total cyanide added to the leaching circuit. This paper presents a description of the cyanide recovery plant and details regarding its current operating efficiency.

Jan 1, 2004