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By George F. Swindle

This paper discusses a composite of two coal reserve studies, each of which made use of a computer-based modeling system to assist in an evaluation of multi-seam deposits. The model permitted simultaneous consideration of seam thickness, seam structure, overburden thickness, over-burden ratio, and quality parameters for sulphur content, ash content, BTU values and the EPA Compliance index. The model is designed for use by a non-programmer, geologist or mining engineer. It enables the user, from a computer terminal in his office, to specify constraints (for example maximum um sulphur and maximum- ash content, minimum seam thickness and minimum BTU rating), and produces a report showing the volume, quality and location of that part of the total in place deposit satisfying all the constraints.

Jan 1, 1983

By Dominique Francois-Bongarcon

The rational and optimal determination of the design of a mining exploitation is a very intricate and difficult problem : the parameters are numerous, some technical, some economic or technico-economic which cannot be fully controlled; beside, deposits are estimated from very limited information and the choice criteria are not always quantitative, the economic context has to be anticipated by several years, and even the technological limits can change tomorrow. So, although very clever and performing numerical algorithms have been developed in recent years for open-pit design, we consider that this problem has not really been solved satisfactorily until now. The reasons are that people have concentrated their efforts on informatical algorithmical problems, and have assumed that the technical and economical data are well defined at the time of the study, which is generally not true. In particular, the mere fact of assigning dollar- values to blocks in order to maximize the total cash-flow is generally unrealistic because of the uncertainty of the data used. Consequently, the significance of the unique pit obtained as a result of these algorithms is questionable.

Jan 1, 1981

Laboratory tests were conducted to evaluate the silica collection efficiency of flooded-bed scrubbers with six different filter panel designs and at two operating velocities. Test results indicated that reductions in filter density negatively impacted respirable dust collection. Silica collection efficiency for the least dense filter was as much as 33 % lower than the collection efficiency of the densest filter. At the low operating velocity, the least dense filter allowed over 40% of the respirable silica dust in the scrubber intake air to pass through the unit, where it would be discharged back into the mine environment. Operation of the scrubber at the higher test air velocity increased silica collection efficiency, regardless of the filter panel tested. The density of the filter panels also impacted the quantity of air that is moved through the scrubber, with higher density filters reducing scrubber airflow. For each filter, the relationship between dust collection efficiency and air moving capacity must be considered to determine overall effectiveness for specific mine applications.

Jan 1, 1998

By Otto E. Zwanzig

You may think long before this talk has been completed that the speaker is belaboring the obvious. Please let me put to rest here and now any doubt which you may have in this regard by assuring you that is precisely my intent, and for a very specific reason. We all profess to know and recognize the obvious, but I am impressed increasingly how often we forget or fail to act upon the obvious. Shortly after starting my first job upon graduation from college, I was asked by my boss to participate in a course on practical communications, particularly as applied to conveying proposals effectively to the client -- be he customer or company president. The concept or philosophy underlying this program was so simple and obvious that in my youthful brashness I saw only a gross waste by the company of e good, solid $1930 in compelling me to take the course. The sequel to this experience occurred about five yews ago when I was directing a 300-man marketing group. At that time I enrolled a dozen of my department heads, and subsequently about a hundred other personnel, in the contemporary version of that sane program. Why? -- because they all knew the obvious, but I could see how imperfectly they were implementing it. Truly, a wide chasm exists all too often in our beliefs on the one hand and our practices on the other.

Jan 1, 1962

By Y. Akin, M. Hancer, M. S. Celik, J. D. Miller

Flotation pulps with boron minerals such as colemanite and borax using primary amine collectors, e.g. dodecylamine, exhibit collector precipitation above a critical pH depending on the amine concentration. This was earlier attributed to the formation of a mine hydroborate. However, results from this current study indicate that the precipitate is dode-cylamine, rather than dodecylamine hydroborate. A systematic study involving solubility, zeta potential, microflotation, adsorption, and surface tension measurements is presented to elucidate the role of a mine precipitates in boron flotation systems.

Jan 1, 2000

By S. J. Zagula

Improved desulfurization of Illinois coals is a widely Shared research goal. The development of a physical cleaning strategy and the results of a project to demonstrate technical and economic feasibility of producing a low sulfur compliance coal from the Illinois Basin are reported. Processing flowsheets to extend or retrofit existing preparation plants are considered. Comminution, conventional and micro-bubble flotation, and selective agglomeration technologies were investigated to maximize pyrite rejection while maintaining high product yield. Batch bench scale testing was followed by continuous pilot plant studies. Parameters included grind size, flow rates, pulp density, aeration, agitation, and reagent dose. An economic evaluation of targeted processes is included.

Jan 1, 1987

By G. T. Lineberry

The Work Crew Performance Model (WCPM) is a method for designing, implementing, and evaluating? performance improvement strategies for machine operators and other mining personnel. The WCPM offers a practical approach for measuring job proficiency and identifying costly behaviors. It enables interventions aimed at performance improvement, especially training, to be assessed monetarily. Two interrelated elements of the WCPM are emphasized: observational techniques for establishing performance baselines and measuring performance outcomes and cost linkages between job competencies and measures related to profitability. Inter-and intra-subject differences in performance-related behaviors of regular and incidental shuttle car operators were detected during field validation of the WCPM. Downtime data were used as outcome measures to test linkages between performance error rates and cost consequences. Use of a simulation program for analyzing continuous mining face operations showed how common shuttle car operating parameters (e.g., payload, tram rate) can be used as cost-conscious indicators of performance variability and therefore as targets for performance improvement.

Jan 1, 1994

By J. Y. Lee, J. Kang

"A selective chlorination process using cuprous chloride (CuCl) was investigated for producing high-grade chalcocite (Cu2S) from chalcopyrite (CuFeS2) feed. The chalcopyrite feed was reacted with CuCl in the presence or absence of sulfur (S) at temperatures between 900 and 1,100 K for five hours under an argon gas atmosphere. The experimental results indicate that iron (Fe) was selectively removed from the chalcopyrite feed as ferrous chloride (FeCl2) at 1,100K and the mass percentage of Fe thus decreased from 31.5 percent in the feed to less than 0.05 percent in the residue, under certain conditions. As a result, high-grade Cu2S was obtained from chalcopyrite in a single step. This new selective chlorination of chalcopyrite using CuCl as a chlorinating agent is therefore feasible for producing high-grade Cu2S.IntroductionCurrently, blister copper (Cu) is commercially produced from sulfide ores by pyrometallurgical methods. These methods entail matte smelting and converting, with the removal of iron (Fe) and sulfur (S) as slag — mainly Fe2SiO4 — and sulfur dioxide (SO2) gas, respectively.In the pyrometallurgical method, as shown in Fig. 1 (Schlesinger et al., 2011), Fe is removed through two steps at high temperatures of around 1,500 K to reduce the loss of Cu during slag formation. However, the slag still contains 1 to 8 percent Cu. Therefore, Cu in the slag is recovered by slag treatment processes, after which the concentration of Cu in the slag decreases to around 0.4 to 1.3 percent. Although Cu is recovered, the slag that had undergone the treatment processes is difficult to use as a feedstock for ironmaking owing to the small amount of Cu remaining in the slag (Schlesinger et al., 2011).In addition, large amounts of SO2 gas are generated by the oxidation of S in the current Cu production process. The SO2 gas generated is captured and used to produce sulfuric acid (H2SO4). However, despite the development of SO2 gas-capture technologies, the emission of SO2 gas is still a problem in terms of environmental considerations.Several studies had been carried out in the past to overcome the drawbacks of the current process. The extraction of Cu from sulfide ores using a chlorination process is one alternative that had been investigated by several researchers. Most chlorination processes used chlorine gas (Cl2) as a chlorinating agent at temperatures between 573 and 1,023 K under an inert atmosphere (Donaldson and Kershner, 1962; Olsen et al., 1973; Kumar, Li and Warren, 1985, 1987; Kanari et al., 1999; Kanari, Gaballah and Allain, 2001)."

Jan 1, 2017

By L. Cui

X. Huang (1997) recently suggested a poroelastic model for simulating the hydraulic fracturing breakdown pressure. His paper began with a discussion questioning Haimson and Fairhurst's (H&F) model. He claimed that the H&F model failed to lead to the Hubbert and Willis (H&W) model as[ a --> 0.] Huang also tried to explain why the H&F model could only work for special types of rock conditions. He pointed out that one possible reason could be that the Terzaghi's effective-stress concept had been adopted. The H&F model (Haimson and Fairhurst, 1969) was derived under the conditions that the borehole wall is fully penetrated (pp = pi) and a drained state is realized (steady pore-pressure field). Cui et al. (1997a) demonstrated that, under drained conditions, the total stresses in the penetrating poroelastic model (identical to the H&F model) degenerate into their counterparts in the elastic model (identical to the H&W model) as [a -- 0.] However, the effective-stress conditions are different for both of these models, because different pore-pressure conditions at the borehole wall were adopted. In the H&W model, p = po was assumed, i.e., the pore pressure field is not disturbed; but pp = pi was assumed in the H&F model. Assuming that Terzaghi's effective-stress controls tensile failure (that was the hypothesis adopted in both the H&F and the H&W models), only the following two special drained poroelastic cases may degenerate into the H&W model for very small a: • when the pore pressure at the borehole wall remains at the same level as the virgin pore pressure for a penetrating model and when the borehole wall is simply impermeable (i.e., the nonpenetrating model, Cui et al., 1997b). Therefore, simply setting a = 0 in the H&F model generally does not lead to the same problem described by the H&W model. On the other hand, when the porepressure boundary conditions do not correspond to the ones in the H&W model, a degeneration of the poroelastic model to the H&W model as [a – 0] should be questionable. The pore pressure at the borehole wall is generally dependent on the injection-fluid pressure and the penetrating conditions at the borehole wall, such as the existence of a filter-cake. For an impermeable wall, pp is independent of Pi, and it is basically an unknown [(how¬ever, pp -- po as t --oo).] For a fully permeable wall, pp is the same as Pi. Between these two extremes, pp should be a function of p; and the permeable condition of the borehole wall, which may be dependent of the leak-off coefficient cf. (the range of cf is from 0 to 1). Theoretically, for a rock with low permeability, a penetrating borehole wall is still possible. For saturated porous materials with very low values of a, poroelasticity shows that a pore pressure will be built up due to the stress concentration subjected to a nonhydrostatic in situ stress field (Cheng et al., 1993). This phenomenon is known as the Skempton effect. The variation of the pore pressure may be evaluated by [AP = 3 B(A rr + 06ee + A (Y,,)] (1) where B is the Skempton pore pressure coefficient. This pore pressure variation dissipates as time increases (it is totally gone as the drained state is approached). The rate of the dissipation mainly rely on the permeability of the formation. The dissipation is very slow for tight formations because their permeability is very low, and it is fast for rocks of high permeability. According to our analyses, the time period for this process could be from seconds (for sandstone's) to a couple of days (for stales). One possible reason that the H&C model did not agree well with the experimental results for rocks with low permeability might be that the time interval between the application of the loading and the fluid injection had not been long enough for the dissipation of the Skempton effect. The effective-stress law basically defines how much pore pressure contributes to the total stress. The difference between Terzaghi's effective stress and Biot's effective stress is that 100% of the pore pressure contributes to the total stress in Terzaghi's definition, while only a certain portion of the pore pressure ((ap) goes to the total stress in Biot's definition. Therefore, when the pore pressure at the boretole wall (pp) is determined according to Biot's effective-stress law, app in the total tangential stress is attributed to the pore pressure. In other words, Terzaghi's effective tangential stress is expressed

Jan 1, 1999

By Kendall Y. Onstott

The paper presents the results of a plant test using WEMCO 1 + 1 enclosed flotation machines for inert gas (nitrogen) flotation of by-product molybdenite from copper sulfide concentrate. Copper depressant consumption in the rougher flotation stage was reduced by 68% as reagent consuming oxygen was removed from the flotation air. Unlike other nitrogen flotation systems used in the industry, nitrogen is recovered above the flotation cells and from froth in tails and concentrate streams and recycled, resulting in minimal nitrogen makeup requirement.

Jan 1, 1984

By A. L. de Vegt

For the past ten years Paques has been engaged in the development and installation of treatment systems based on biotechnological processes to remove sulfur compounds from water, air and gaseous streams. Metal and sulfate can be removed from mine waters using two biological steps: 1. Sulfate reducing bacteria convert sulfate to hydrogen sulfide (H2S). The H2S reacts with the dissolved metals to form insoluble metal sulfide precipitates. 2. Sulfide oxidizing bacteria convert excess H2S to elemental sulfur. Paques has designed and installed a groundwater treatment system for the Budelco zinc refinery in the Netherlands to remove metals and sulfate as described above. The system has been operating since May 1992 treating a flow of 5000 m /d. A pilot plant started operation in November 1995 at Kennecott's Bingham Canyon Utah copper mine to develop the processes for metal and sulfate removal from groundwater and selective copper recovery from leach water. The principle of the biotechnological methods, full scale experience, and an overview of the test program at the copper mine are presented.

Jan 1, 1997

By F. Daviess

A requirement for geological controls during orebody modeling results from the recognition of heterogeneous geological characteristics and/or abrupt variations in orebody geometries. While purely statistical methods are often sufficient for modeling uniform homogeneous deposits, and the only recourse for many that are extremely complex, geological interpretations can be extremely valuable as controls during the modeling process. The advent of relatively inexpensive, sophisticated graphical computer hardware and software has focused considerable attention on the three dimensional visualization capabilities now available to the mining industry. Orebody geometries can be easily imported into many systems as wireframe or solid models, rendered with shading and color, rotated in space, exploded into composite parts, zoomed into and otherwise displayed to awe any audience. The requirements for an initially meaningful, accurate, geological interpretation are sometimes lost when the focus is on an apparently complex, highly resolved end product. Details of the initial data and sensitivities of modeling assumptions are not always sufficiently scrutinized. Software capabilities have extended the geopoetic license into three dimensions. The new tools, while greatly facilitating model construction and rendering, have done little to expedite basic data preparation and analysis. This paper attempts to briefly summarize the purpose and method of the construction of geological controls. The examples selected are from wire­framing and block modeling; application software processes commonly used in the mining industry today.

Jan 1, 1992

By T. E. Bernard

"Refuge alternatives (RA) provide shelter to miners trapped underground during a disaster. RA manufacturers must demonstrate that their RAs meet the Mine Safety and Health Administration (MSHA) requirements for oxygen supply, carbon dioxide removal, and the management of heat that results from the RA occupants and mechanical/chemical systems. In this study, miner size and activity level were used to determine the metabolic heat rate, oxygen requirements, and carbon dioxide generation that is representative of miners in a refuge situation. A convenience sample of 198 male miners was used for the distribution of current US coal miners, and the composite 95th percentile height and weight were determined to be 193 cm (76 in) and 133 kg (293 lb). The resting metabolic rate (RMR) was determined to be representative of activity level in an RA. The highest likely metabolic heat generation ranged from 115 W to 135 W, depending on RA occupancy. The highest required oxygen supply and carbon dioxide removal were estimated to be 23 LO2/h/person (0.81 ft3/h/person) and 20 LCO2/h/person (0.71 ft3/h/person), which means the margin of safety is 50% or more when compared to the MSHA requirements. INTRODUCTION Refuge alternatives (RAs) provide shelter to miners trapped underground during a disaster. Manufacturers must demonstrate that their RAs meet Mine Safety and Health Administration (MSHA) requirements for the supply of oxygen, the removal of carbon dioxide, and the management of heat that results from the occupants and the mechanical/chemical systems in the RA [1]. These MSHA requirements were based on a standard 70 kg (168 lb) male with an assumed allocation of activity of 80% rest and 20% moderate activity level [2]. The purpose of this paper is to re-examine the metabolic heat generation and oxygen and carbon dioxide requirements of miners in an RA based on actual miner size and more realistic RA activity levels based on current RA designs. The purpose of this paper is to re-examine the Mine Safety and Health Administration (MSHA) requirements for oxygen supply, carbon dioxide removal, and heat generation. To achieve this, researchers took the following steps to estimate the metabolic demands and the associated heat generation, oxygen requirements, and carbon dioxide production. 1. Characterized the anthropometric characteristics of the miner population. 2. Described the metabolic rate profile of RA occupants. 3. Characterized the maintenance demands of RAs. 4. Summarized oxygen supply and carbon dioxide removal volumes. ANTHROPOMETRIC CHARACTERISTICS OF MINERS The weight, height, and age distributions of the adult male populations are summarized in Table 1. For each data set, the reported mean and standard deviation are provided. The 95th percentile (%ile) value for height and weight for each population was the mean plus 1.64 times the standard deviation."

Jan 1, 2017

By Felicia F. Peng

A laboratory fixed bed reactor was used in a study of generating clean thermal energy from coal fine refuse-limestone agglomerates. The major operation variables, including Ca/S mole ratio, agglomerate size, air flow rate and temperature, which affect the rate of sulfur fixation and combustible material utilization, have been examined. The test results show that 70 percent or more of sulfur fixation and 100% of combustible material utilization can be achieved depending upon sorbent, agglomeration, and combustion conditions. The coal fine refuse limestone pellet combustion process (CLC process) requires a simple flowsheet to convert coal fine refuse as a clean solid fuel, while meeting the strict air quality standards for SO2 emissions into the atmosphere. The CLC process is an attractive method to clean up coal slurry impoundments to protect our environment.

Jan 1, 1984

By S. T. Hall

The authors have previously described a method of enhancing the magnetic susceptibility of pyrite by a mild alkaline oxidative pressure leach (Hall et al, 1985). This finding was successfully applied to enhance the magnetic desulfurization of an Eastern Canadian coal (Hall and Finch, 1984). This paper reports on enhancement of the magnetic susceptibilities of iron-containing sulfides (arsenopyrite, chalcopyrite and marcasite) upon similar treatment. It also explores the application of this pretreatment in the magnetic separation of fine sulfides from oxides and other sulfide minerals. In the latter case galvanic interference effects have a serious impact on the potential use of this method.

Jan 1, 1985

By Russell L. Wood

The title of this session seems to have been picked especially for this paper. It is 1984, it is the morning after, and there is one monumental hangover among many if not most of the oil companies that have invested in mining in the past decade or so. How an oil company looks at mining depends on what time period you are talking about. A few years back around the time of investment this is what they were probably looking at: 1. A balance sheet of their own that was beginning to go wild, with many of their commodity prices having already seen increases of two, three, or four fold, and with no end in sight. 2. A need to invest their earnings someplace fast before the stockholders or the government got too interested. And that someplace should be in an industry where their own management skills could be applied. (Only a true cynic would suggest that this is a form of job security) 3. In mining there was an industry amazingly similiar to their own, one working with non-renewable natural resources, dealing with the same types of government agencies, and having the same type of critics and pressures from the general population. 4. An industry that was somewhat backward as compared with their own, and one where a generous ration of the capital and management skills so handsomely bestowed upon the oil industry could be used to great advantage.

Jan 1, 1984

By Robert G. Bottge, Paul C. Hyndman, Don J. Barnes, Clark A. Roberts

The effect of Federal restrictions on Federal mineral estate in Alaska and the Western States is being addressed by systematic, State-by- State studies. The Bureau of Mines has inventoried and classified 3.5 million sq km (876 million acres) of land, section-by-section, according to 1) mineral ownership, 2) availability for mineral exploration and development as affected by Federal restrictions, and 31, areas containing mines and mineral resources. The availability of Federal land for exploration and development is spatially compared to areas containing mines and mineral resources. The methodology and overall results of the studies are presented.

Jan 1, 1991

By W. H. Wilson, G. Bjarnholt, D. C. Holloway

This paper describes the results of field tests conducted on a 5x25m bench face to evaluate several new concepts for improving smooth wall blasting. These ideas involved the use of notched boreholes to direct the fractures and unconventional types and placements of explosives. The notches were made with a mechanical broaching tool, a water jet and with shaped charges. Borehole pressures were measured with an inexpensive and expendable pressure transducer developed for this program. The testing showed that at hole spacings 38% greater than normal practice, notched holes with half the normal loading density produced equivalent results.

Jan 1, 1986

By Ava Walker

The first form of a surety bond was an honest handshake between two or more parties agreeing to a decision, and their personal guarantee of following through to completion. This has all changed. In 1895, the United States Treasury Department disclosed that $35 million worth of personal surety guarantees on file had become worthless. A law was then passed requiring all surety bonds, in favor of the United States, must be corporate surety bonds. Today, a surety bond is one of the nation's leading fi¬nancial instruments used to guarantee the completion of an obligation. One hundred-fifty years before cor¬porate surety bonds, outcrops near Richmond, VA, were being mined. These surface mines became under¬ground mines. Today, both are still being used to obtain a leading energy source, coal. Since that time, more than 5956 km2 (1.47 million acres) of coal mined lands have been reclaimed in the US (Coal News, August, 1987). More than 25,000 state and Federal mining permits cover¬ing 14,164 km2 (3.5 million acres) have been issued during the last 10 years. Coal production has exceeded 7.2 Gt (8 billion st). More than 5665 km2 (1.4 million acres) of mined land has been reclaimed by active coal mining opera¬tions and 267 km2 (66,000 acres) of abandoned mined lands have been re¬claimed by others. Reclamation bonds were freely writ¬ten in the 1970s. So why are they almost extinct today? Contract bond losses have been severe in the past several years, sureties reporting losses exceed¬ing 110%. But the same proof is not provided on coal reclamation bonds. A surety bond is generally required when one party has an agreement with another party, and that party wants a guarantee from a third party that a job will be completed according to the terms and conditions of a written contract. In the case of a reclamation bond, the surety company (surety) is the financial party. It extends the credit and a guarantee to the obligee (the State, Commonwealth, or Office of Surface Mining) that the principal (the coal operator/company) will complete the terms and conditions of the contract (the rules and regulations governing mining and reclamation). The Surety Association of America defines a surety bond as an agreement providing for monetary compensation should there be a failure to perform specified acts within a stated period. Webster's Dictionary defines surety in the following ways: "l: the state of being sure; 2a: a pledge or other formal engagement given for the fulfillment of an undertaking and; 3b: one who has become legally liable for the debt, de¬fault, or failure in duty of another." Banks never make accommodation loans. Either the loan is good or no loan is made. Surety companies feel the same way about surety bonds. In fact, the average person does not realize the dangers of becoming surety for another. How does a surety determine if a company is worthy of receiving surety credit? How is a coal account under¬written today for an obligation that may not be released for many years? When a surety company executes a reclama¬tion bond, it financially puts its name behind the coal company and its guaran¬tee that should the coal miner default on the obligation, the surety will fulfill the contract. How is the surety to determine if a coal company may still be in business five, 10, 20, or 40 years from today?

Jan 1, 1989

By D. R. McMullin

The purpose of this paper is to provide a method for mine planners and engineers to evaluate on a conceptual basis if a shaft or a ramp is most suited for their particular underground access requirements. Mine planners and engineers are often raced with the decision of choosing which method of underground access is best suited for their particular requirement. Underground access can be provided by a shaft, ramp, adit, or slope for either exploration and/or actual production operations. This paper will focus on the construction cost and schedule differences between sinking a shaft and excavating a ramp which are currently the most typical access alternatives used in the western United States. It would be wrong to state that one method is superior to the other in every case. There are many variables to be addressed, and the degree of sensitivity of each of them will eventually dictate which method is the most suited to the particular circumstances. This paper compares the construction cost and schedule or sinking a shaft to excavating a ramp at different depths given different ground and hydrological conditions. This comparison provides mine planners with "rules or thumb" that may be applied to the access selection process.

Jan 1, 1994