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By J. E. Nesset, F. Rosenblum, J. A. Finch

"The self-heating of sulphides can be a major hazard in mining operations and concentrate handling, particularly during transportation and associated storage. Self-heating results from the oxidation of sulphide minerals and can vary from being insignificant to highly reactive and potentially hazardous to both humans and infrastructure. It is essential that there be a reliable test methodology that can measure and categorize a given sulphide material as to its self-heating potential. By their nature, sulphide ores and concentrates are complex and variable mineral mixtures making it difficult to predict their self-heating behaviour a-priori based on mineralogy or with a simple “snapshot” test. Furthermore, self-heating behaviour will depend on the state of oxidation of the sulphides as well as time, temperature and humidity. A review of available testing apparatuses and protocols that can be used to assess self-heating potential is presented. Each of these methodologies was examined in relation to its ability to measure and reliably predict the latent self-heating hazard of a sulphide material. Several of the methods were tested and compared to illustrate their strengths and weakness. The results indicated that a number of the test protocols may produce false negative indications of self-heating potential, constituting an obvious concern to the industry.INTRODUCTION Sulphides as well as other materials (coal, wood chips, hay, powdered milk, to name a few) that are stockpiled in an air atmosphere may undergo oxidation reactions which can result in the evolution of heat (Beever, 1984) (Hudak, 2002) (Blanchard, 2007). If the rate of heat generated exceeds the rate of heat dissipation, the stockpile temperature will rise, potentially leading to “hot spots” in the most reactive areas, and possibly even fires. The heat generation rate, the “self-heating” rate, depends on many factors such as the type and composition of material, particle size, moisture content, oxygen availability, ambient temperature and humidity, and of prime importance, the extend of prior oxidation, or more specifically, the presence of oxidation products. The desire of operators that mine, process or transport sulphide-bearing materials with a potential for self-heating is to have an accepted and reliable method for evaluating and quantifying the potential hazard of their material. The challenges are how to best measure the self-heating properties of given samples, and based on results, predict the behaviour of the bulk material over time and in-situ. Generally, when evaluating a given material one derives the self-heating characteristics of that sample at the time and under the conditions of testing, which will be referred to as a “snapshot test”. If that material is invariable, i.e. it will not change its response over time, then it may be considered to be a “predictive test”. However, if as a result of continuing oxidation or other changes, the material becomes more or less reactive with time, then a “snapshot test” is unreliable with respect to predictive ability."

Jan 1, 2014

By D. L. Luffel

This paper presents two main developments: (1) a short, constantly accelerated centrifuge method of measuring drainage capillary pressure properties of cores, and (2) a new analytic method of treatment of centrifuge measurements to obtain saturation-capillary pressure relations. Toward the first objective, a clever experimental method is presented which is certainly more rapid than previous centrifuge methods. Toward the second objective, a new analytic method is derived to eliminate the approximate method of Hassler and runner. The derivation of this new analytic method, however, appears to be in error. The new analytic solution is developed as Eq. 5 in Appendix A. At the beginning of this derivation, the average wetting phase saturation of a core is expressed as, where is the centrifuge angular velocity. Eq. D1.2 makes explicit the dependence of S and S upon The second equation shown in Appendix A expresses the relation between the three variables Since for a given porous medium the saturation is uniquely related to capillary pressure, the functional dependence of S upon P is trivial, i.e., Pc.ri does not actually appear. Thus, the function 5 (r, ) may be expressed as a new function, S*, of PC, , alone The author transforms the variable of integration in Eq. Dl through use of Eq. D2 and writes

Jan 1, 1965

By R. L. Howell, L. C. Atkinson

Typical sedimentary sequences overlying coal seams consist of interbedded sandstones, siltstones, shales, and rider coal seams. In many surface coalmine settings, these sediments are saturated; and prior dewatering of them is necessary for effective and economic mining, including the stacking of saturated spoils. Such sedimentary sections usually have a very low vertical hydraulic conductivity that does not allow them to drain in a timely manner prior to their being stripped. One potential solution is installation of drainwells. Drainwells are small diameter wells that can collect water laterally from the various more permeable layers in the overburden and then gravity drain it to a lower layer – often the coal seam being mined – where it can be removed by pumping wells or sumps located in the bottom of the pit. A ground-water flow model utilizing the 3-dimensional finite element code MINEDW has been used to evaluate the effectiveness of usingdrainwells in a hydrogeologic setting that is typical of the Powder River Basin. A series of numerical simulations were completed using various combinations and spacings of drainwells and pumping wells to dewater the overburden and coal seams. The numerical simulations suggest that drainwells can be a very effective method of overburden dewatering.

Jan 1, 2000

By R. V. Taborelli, P. B. Bucky

This investigation was carried on by means of models and the application of the principles of similitude to determine the effects of props, props and cribs and sand filling in longwall mining. The geologic structure and rate of face retreat were kept constant and the only change introduced was in the method of support. It is not felt necessary to repeat a description of apparatus, or to explain the fact that a scalar model made in all parts of the same material as the prototype will behave similarly to the prototype when rotated at speeds such that the centrifugal force is as many times the gravitational force as the prototype dimension is a similar linear model dimension. The reader is referred to earlier papers1,2 for further information regarding these statements. All models were made of sandstone and were as in Fig. 6. They are composed of a 3/16-in. ore body bed A, overlain by a 3/16-in. bed B, a ?-in. bed C and two ?-in. beds D and E. The model was rotated at + 2350 r.p.m. equivalent to a model ratio of 1268. It was worked back ¼ in. at a time before being replaced in the centrifuge and again rotated. Table 1 gives model and prototype dimensions occurring in this discussion, the prototype dimensions being 1268 times the model dimensions. Figs. 1, 2, 3 and 4 were taken while the model was rotating at 2350 r.p.m. One was taken for each face retreat of 26.4 ft., but for obvious reasons all are not presented. Fig. 1 (A-E) shows the behavior of this type of structure with face retreats of 26.4 ft. and no artificial support. Fig. 2(A-E) shows the behavior of this type of structure where breaker and face props were used. The props were exceptionally strong, being of steel ? in. square in cross section, and capped with 1/16 in. ± of soft wood and paper, to allow for roof deflection. The face props were

Jan 1, 1940

By P. B. Bucky, R. V. Taborelli

This investigation was carried on by means of models and the application of the principles of similitude to determine the effects of props, props and cribs and sand filling in longwall mining. The geologic structure and rate of face retreat were kept constant and the only change introduced was in the method of support. It is not felt necessary to repeat a description of apparatus, or to explain the fact that a scalar model made in all parts of the same material as the prototype will behave similarly to the prototype when rotated at speeds such that the centrifugal force is as many times the gravitational force as the prototype dimension is a similar linear model dimension. The reader is referred to earlier papers1,2 for further information regarding these statements. All models were made of sandstone and were as in Fig. 6. They are composed of a 3/16-in. ore body bed A, overlain by a 3/16-in. bed B, a ?-in. bed C and two ?-in. beds D and E. The model was rotated at + 2350 r.p.m. equivalent to a model ratio of 1268. It was worked back ¼ in. at a time before being replaced in the centrifuge and again rotated. Table 1 gives model and prototype dimensions occurring in this discussion, the prototype dimensions being 1268 times the model dimensions. Figs. 1, 2, 3 and 4 were taken while the model was rotating at 2350 r.p.m. One was taken for each face retreat of 26.4 ft., but for obvious reasons all are not presented. Fig. 1 (A-E) shows the behavior of this type of structure with face retreats of 26.4 ft. and no artificial support. Fig. 2(A-E) shows the behavior of this type of structure where breaker and face props were used. The props were exceptionally strong, being of steel ? in. square in cross section, and capped with 1/16 in. ± of soft wood and paper, to allow for roof deflection. The face props were

Jan 1, 1940

By Foster Fraas

Review of the literature on solid solutions discloses that the relation between composition and magnetic susceptibility is not linear . Recalculation using a transformation of composition values to parameter v values provides for a linear relation with the magnetic susceptibility to the 1/2 power . Application to minerals is illustrated by the olivine and enstentite series .

Jan 1, 1964

By K. Voltaire

As can be guessed from the subtitle, this paper will not be a geologist's one since neither of the authors is a professional geologist. This will be an attempt to present the various aspects of the legal, economic and geological setting that condition the exploration for mineral resources in Haiti. Before going any further, we are going to present a summary of our rather short mining history. One must first mention that Caribbean countries are latecomers to the mining business. If we go back to the colonial period (1500-1600's) there are net many traces of mining activity. The major exception to this is the recovery of alluvial gold in Hispaniola, Puerto-Rico and Cuba and also some sporadic copper mining in Hispaniola (notably in Haiti near the city of Gonaives and in some of the old mining districts in Santo-Domingo). These easily minable deposits were quickly exhausted and mining quite naturally came to an end as agriculture rose as the major economic activity. In the Haitian case, aside from very erratic mention during the 19th Century of the presence of some minerals (i.e. haematite, chalcopyrite) no serious geological work was undertaken. In the meantime, the peasants in the northern part were still looking for alluvial gold in some streams but this amounted to next to nothing. One has to come to the 1920's to find the first comprehensive geological survey. At the time, the country was under the military control of the United States. The American Government sent a team from the U.S.G.S. headed by the late W. Woodring to initiate a survey of the country. Given the lack of transportation, this was a tough task and Woodring and his associates did it magnificently. As a result of their efforts, they published a very thick piece of work of more than 600 pages. "The Geology of the Republic of Haiti" although it was published in 1924 is a classic and is a must for anyone interested in the geology of Haiti.

Jan 1, 1978

By Jogeshwar P. Singh, Aser I. Abbas, Mohamed Ashour

The presented methodology predicts the pile head response (i.e. pile head load - displacement curve) and develops the load transfer (t-z) curve of piles in sandy soils under tension forces based on soil/pile properties and soil-pile interaction. The proposed approach improves the prediction of the t-z curve in sandy soils compared to current practice. The method employs a nonlinear soil constitutive model to calculate the mobilized shear stress/strain in soil at the soil-pile interface induced by pile upward displacement. The approach accounts for the influence of the pile slenderness ratio on the predicted t-z curve and is validated through comparisons with measured pile head response and t-z curves from full-scale pile load tests. INTRODUCTION Piles may be subjected to axial uplift forces due to either static loading or cyclic loading. The majority of methods are only concerned with the pile ultimate tensile capacity. However, the mobilized pile stiffness (i.e., pile-head load-displacement relationship) is essential to determine the interaction between the foundation and the superstructure and consequently the performance of the whole structure. Methods that assess the pile ultimate tensile capacity usually assume the failure surface at the soil-pile interface and estimate the local side shear resistance using a lateral earth pressure approach. The Naval Facilities Engineering Command (NAVFAC 1986) and the US Army Corps of Engineers (USACE 1991) employed Eq. 1 to assess the ultimate shear stress (τ) developed at the soil-pile interface.

Jan 1, 2018

By P. D. Kovscek

The Bureau of Mines has tested a low-thrust water-jet-assisted rotary drill. This work was performed to evaluate the performance of a water-jet-assisted drill operated at thrust levels typical of a handheld manual-thrust operation. Prior work by the Bureau had indicated that using water-jet assist with high-thrust drilling applications would increase drilling rate. Small-diameter holes were drilled in five different types of rock. Thrust and water pressure were varied as the drill rate was monitored. The test results indicate that drilling rates increase with increasing water pressure and thrust. The water jet has more effect on reducing the specific energy when drilling in the harder rocks than in softer rocks. Variation in drill rate for a given rock sample is attributable primarily to the material heterogeneity within the sample. One rock type (Greenwich sandstone) could not be drilled efficiently with the water-jet-assisted drill.

Jan 1, 1988

By I. R. Ward

"The need for energy conservation has been of increasing concern since the early 1970's, when the cost of petroleum based energy began to escalate rapidly and security of supply became uncertain. The cost of energy from alternative sources has also increased due to development costs and environmental restrictions.These developments have had a serious impact on the mining industry, which is energy intensive. The impact is magnified as lower grade ores are treated, and more energy is consumed per unit of product. In many cases increased operating cost is not compensated by the rise in product selling price.The magnitude of energy consumption in the mining industry is indicated by recent studies conducted in the U.S.A. and Canada. Based on 1970 figures, it was reported that the production of 1 ton of copper in the U.S.A. required 111. 8 x 106 BTU of energy, of which 60. 7 x 106 BTU (54.3%) was consumed in mining and processing (l)The survey of Canadian mills, conducted by CANMET and reported to the CMP meeting of 1978 (2), showed the following milling energy consumption figures (approximate averages):"

Jan 1, 1981

By Levent Ozdemir, Bjorn Nilsen

For several recent TBM tunnel projects, unexpected ground conditions have been encountered, causing extra cost, considerable delay, and in some cases major claims. Undoubtedly, insufficient and/or irrelevant site investigation and testing are among the main causes of such incidents. The purpose of this paper is to review the main investigations and tests relevant for hard rock TBM projects, with particular emphasis on the considerable development that has taken place over the last few years. Also, guidelines for defining optimum scope and extent of site investigations and testing are discussed, as well as the importance of adjusting the investigations and tests according to complexity of the ground conditions and project type.

Jan 1, 1999

By S. L. Lebo, J. D. Gargulak

Lignin, the second most abundant natural polymer and bi-product of the pulp and paper industry, has been commercially available in a number of forms since 1940. This growing industry is fueled by demand in traditional applications. Reagents that offer unique solutions in various mineral process applications are examples of advanced uses that also fuel growth. These applications include flotation reagents in fluorspar, bastnäsite and potash, as well as in the zinc pressure leach process. Due to the fact that no concerted effort has been made to find applications for modified lignosulfonates, it is quite possible that this natural material will find use in other benefication processes.

Jan 1, 2002

By C. Vanvoren

"Since 1975, the Aluminium Pechiney Research Centre at Saint-Jean-de-Maurienne (LRF) has been concentrating its efforts on designing, testing and perfecting the Aluminium Pechiney point-fed prebaked reduction cell.In 1979, the AP18 cell (180 kA) was industrially launched with the construction and start-up of the F line in Saint-Jean. The following generation, the AP30 (300 kA), with prototypes started in 1981, was launched in 1986 on the Saint-Jean G line. Along with cell design, efficient process control systems were developed to pilot alumina feeding and bath composition. Together, these pots are currently producing 4.6 Mt of aluminum, i.e., 18% of the world’s overall yearly production.In 1989, the research centre faced a new challenge: to push the limits for the size of a reduction cell to further improve the profitability of Greenfield projects. This new generation development was also the opportunity for a significant redesign of the Aluminium Pechiney electrolysis information system.With a track record of ten years of semiindustrial operation with three prototypes, the AP50 technology is now ready for industrial implementation and enables a significant breakthrough to be made in terms of return on investment of a Greenfield smelter."

Jan 1, 2002

By W. A. Hoyer

Neutron activation analysis for mineral identification has attracted the attention of numerous investigators, judging from the publications on this subject in the past few years. 1-9 The appealing aspect of this method of mineral analysis is its proven sensitivity in the laboratory. In principle, activation analysis is one of the few petro-physical methods whereby a direct analysis for a mineral itself is possible in a borehole. The successful application of activation analysis requires the use of particular neutron reactions, measurement of selected gamma-ray energy intervals, and optimum bombardment and detection times. For copper analysis, Labanov et al., 10,11 using a low-energy PuBe source, reported an acceptable logging means. On the other hand, Pradzynski12, in analyzing ores and process tailings, used high-energy neutrons and photons for surface measurements of process samples. The work of Labanov et al. was based on measuring the rate of decay of the activated copper and hence was not as definitive as might be desired. Equipment is commercially available to carry out activation studies in the field 13,14 Gamma-ray spectra can be successfully transmitted over ordinary logging cables and, with borehole high-energy neutron accelerators and lower-energy chemical neutron sources, a variety of neutron activation methods can be studied. The purpose of the study discussed in this paper was to determine the feasibility and practicability of logging for copper using neutron activation techniques and commercially available equipment. The laboratory study showed that Cu could be detected in rock samples in the laboratory by high-energy neutron activation of 63 Cu. In the field, however, due in part to the large volume irradiated, the direct detection of copper using high-energy neutrons was not as promising. Detection of copper by measuring both the direct gamma-ray emission and the excessively strong low-energy gamma-ray absorption appears promising. Copper was not detected either in the laboratory or

Jan 1, 1972

The Mine Safety and Health Administration (MSHA) defines an independent contractor as “any person, partnership, corporation, subsidiary of a cor-poration, firm, association or other organization that contracts to perform services or construction at a mine.” Contractors that perform specific types of work are required to report the number of employees who work at coal mines and noncoal mines.

Sep 1, 2007

By Carlos Soria

El presente texto describe los Sistemas de Gerencia de la Información y su aplicación en la industria minera con el objetivo de optimizar la gestión total de la empresa. Dichos sistemas manejan información del proceso y sus valores de producción, cálculos, consumos de energia, emisiones de plantas, tiempos de funcionamiento de equipos, eventos, alarmas, mediciones de laboratorio y control estadístico, etc. De forma que dicha información pueda ser reunida y consolidada, convirtiéndose en materia de significado y relevancia disponible en base a análisis, reportes, listas, tendencias y gráficos para que el usuario final de una planta o en sus oficina pueda tomar mejores decisiones.

Jul 17, 2000

By Dan A. Brown

The following paper was written by Dr. Dan A. Brown, P.E. Brown is an Associate Professor at Auburn University's Department of Civil Engineering. The paper was originally presented at a FHWA's Transportation Research Board meeting and is presented here with the author's consent. Construction and design of drilled shaft foundations in hard pinnacle limestone requires flexibility from all parties involved due to the variability of the subsurface conditions. This article describes some strategies which have been found useful in the Birmingham, Alabama area. The importance of well trained and experienced field personnel in these conditions is noted. It is also vital that engineers understand the construction challenges so as to provide both quality assurance and cost effectiveness in design and in the specifications.

Jan 1, 1991

By G. S. Pauley

Paper presented at a meeting on: Artificial intelligence in the minerals sector, held in Nottingham, UK, 20 April 1993 (original title: Case-based reasoning can be a catalyst for improvement). A new computer software technology known as Case Based Reasoning (CBR) can be used to produce small decision support systems that are economically viable. This is because the knowledge that they contain can be owned and maintained by their users. A CBR tool has been used to perform a pilot study with Anglesey Aluminium Metal Ltd. The results are encouraging. They suggest that a combination of CBR and participative design and implementation techniques (such as Checkland's Soft System Methodology) can achieve sustainable improvement in mineral processing functions. An explanation is presented of why traditional, rule based systems are often an ineffective way to implement support systems. It is shown that CBR may provide an appropriate technology solution. Methods of achieving sustainable benefit are indicated. The pilot study with Anglesey Aluminium Metal is used as a practical illustration of the development of a CBR application. A review of potential application areas and some observations about the implementation are presented

Apr 1, 1994

By Mohsen Sanai, Paul Gefken

"SRI International has developed and patented* a castable dilute explosive tile @ET) that offersunique advantages over conventional high explosive. The primary advantages of DET are that itsdetonation pressure can be adjusted over a wick range and its impulse can be controlled independently by adjusting its thickness and configuration. Because DET has a much lower detonation velocity than conventional explosives, the pulse duration produced by DET is as much as 10 times longer than the pulse duration produced by conventional explosives for equal explosive weights. These features of DET present several advantages to the mining industry. For example, DET can be tailored so as to control fragment size and distribution to enhance extraction of desired elements from ore or breakup of specific regions."

Jan 1, 1995

By Harumasa Kurokawa

Since the initial start-up, the Toyo Smelter & Refinery has been operating in harmony with the ambient environment, and improvements have been implemented with technologies specifically developed for further protecting the environment. Toyo Smelter & Refinery is now planning to increase the copper production capacity from 280,000 tpy to 450,000 tpy, over a period of several years. In 2003, the first step of this smelter expansion and modernization plan was implemented. The production capacity of the P-S converter was increased dramatically, as it became possible to operate under a ?2 hot-2 blowing? schedule. In 2005, an additional converter will be installed, in order to allow operation under a ?3 hot-2 blowing? schedule. This report will describe the technical improvements on the P-S converters, as well as describe the Toyo expansion program and discuss the technologies applied to the fugitive gas collecting system.

Jan 1, 2005