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By W. G. Pariseau

"BACKGROUND Strata mechanics of three underground coal mines in central Utah were recently studied using a specialized finite element technique [1, 2, 3, 4]. The purpose of these studies was to examine relationships between mining and related seismicity. The longwall mining method was predominant, but room and pillar mining and barrier pillar mining were also used in the mines studied. In every case, high correlation between face advance and seismicity was observed. The specialized finite element technique allows for whole mine subsidence estimation at a kilometer scale and for stress concentration at a meter scale near a working face. Comparisons of observed mine subsidence with model subsidence allows for model verification and justifies detailed analysis of the evolution of stress at seam level. Yielding is expected near a longwall panel face and as the face is advanced the extent of yielding is expected to increase. The total number of element failures in a finite element mine model also increases, so a high correlation with associated seismicity, say, event count, is not so surprising. A brief review of recent coal mine studies in Utah is presented in the sequel. The procedures are given in some detail in application to trona mining. COAL MINES The analysis procedure begins with the geologic column and proceeds to specification of strata properties including elastic moduli and strengths. Joints are an integral part of the geologic model and joint set specifications include dip direction, dip, spacing, stiffness and strength. Spatial variability of strata properties in situ may be taken into account during analysis. Topography is important, especially to Utah coal mines that are developed from outcrop in regions of high relief. Mesh generation follows specification of data input. Finite element analysis is next, followed by reporting of results. In this regard, all finite element computations are based on first principles. No model “calibration” is done that involves adjusting computer input to obtain a fit to mine measurements such as subsidence profiles. Figure 1 illustrates the concept of a dual node – dual mesh finite element concept. Dual nodes are roof and floor nodes in mined areas. These nodes replace the seam. The dual mesh is a much refined mesh with displacement boundary conditions obtained from the big mesh and thus replaces the effect of mining in the region outside the dual mesh. The refined dual mesh allows for details of stress, strain and displacement near a working face of interest. Strata Properties Strata properties include elastic moduli and strengths of intact rock between joints and joint stiffness and strength for each joint set present. Both properties sets may be obtained from laboratory test data, although testing joints poses a sampling problem in the field. The statistical variability observed in laboratory test data, say, in unconfined compressive strength tests is often characterized by much variation. In fact, the coefficient of variation, ratio of standard deviation to mean, is often greater than 35 percent. When sample values are mapped back to the mine location, one may observe spatial variability as properties vary from place to place as shown in Figure 2. Spatial variability may be incorporated into a finite element analysis with probabilistic assignment of properties to elements in accordance with measured variability. The result is a more realistic model of rock in situ."

Jan 1, 2017

By Derek J. Barratt

The existence of a critical size buildup in an autogenous or SAG mill can be predicted from proper examination of drill core and ore samples. Methods of dealing with such critical size in a primary mill are reviewed in the context of ore properties, whether or not pilot plant-scale testwork has been conducted, and also with respect to the design of new plants or the retrofitting of existing operations. The implications of not planning for pebble crushing in situations where it is appropriate are discussed.

Jan 1, 1992

By BUREAU OF MINES

PLATINUM

Feb 1, 1922

By Zhang Libo, Peng Jinhui, Zhang Zhengfu, Fu Mengbi, Han Yamei

In this paper, results of a novel synthesis method of carbon-coated LiNi113Mn113Co11302 cathode material for lithium-ion battery are reported. The carbon coating was produced from a precursor, glucose, by microwave-pyrolysis method. The structure, morphology and electrochemical performance of the bare and carbon-coated LiNi113Mn113Co11302 were characterized by X-ray diffraction, scanning electron microscopy and charge-discharge tests respectively. The L8(27) orthogonal experiments were carried out to optimize LiNi113Co113Mn1130z/C technological conditions. The conditions of the orthogonal experiments were that the glucose content were 1.5 % and 4 %, the holding time were 15min and 30min, the heating temperature were 400 °C and 500 °C and the solvent were H20 and CH3CH20H. The main experiment target include specific capacity at 0.1C and 0.2C, Capacity retention rate, medium voltage attenuation rate and The fifth discharge medium voltage. The data were analyzed by Minitab 14 statistics software. The results of analysis of variance indicated that the most influential factor was the glucose content despite of discharge rate. Secondly, the effect of the solvent was equivalent to the holding time.

Jan 1, 2013

By Grainne A. Matthews

Jan 1, 2008

By A. W. Deurbrouck

The Bureau of Mines analyzed 13 samples collected from three Randolph County coalbeds. The Peerless and Sewell bed samples were generally of metallurgical quality as received from the mines or could be easily upgraded. How-ever, the Lower Kittanning coa1bed samples proved to be quite inimical to upgrading to metallurgical quality.

Jan 1, 1966

By J. Visman

"Cyclone separators of different design are being used in increasing numbers in the coal industry of today. One recent addition, the Compound Water Cyclone, is finding application in the North American and Australian coal fields for the beneficiation of coking coals and for the reduction of sulphur and ash in steam coals. In this paper, the combination of specific-gravity separation, thickening, classification and water recovery are discussed. All of these operations can now be accomplished by means of cyclones that are effectively combined in circuits of compact design. In the layout of such integrated plants, three main sections are distinguished, namely: a Main Section for cleaning the plus-28-mesh fractions; an Effluent-Beneficiation Section for treating the minus-28-mesh fractions; and a Water-Recovery Section, where the wash water is reconditioned, and the fine solids are removed in a semi-solid state as slugs or pellets. Depending on the nature of the coal and the specifications of the purchaser, water-cyclone circuits can be flexibly combined with HM Cyclones and froth flotation, as well as with ancillary equipment for dewatering and drying."

Jan 1, 1968

Ferric (Fe3+) ions are omnipresent in flotation circuits. Depending on pH and the nature of the ore body, Fe3+ ions may play a role in the adsorption of thiol collectors on sulfide minerals. To investigate this possibility, a two-compartment galvanic coupling cell was designed. This cell was used to monitor changes in contact angle of a sulfide mineral in one compartment, while varying concentrations of the Fe3+ ions in the other. The results showed that Fe3+ ions promote xanthate adsorption as indicated by the increase in contact angle. Implications of this finding in sulfide mineral flotation in general will be discussed.

Jan 1, 1998

By B. D. H. Knights

In November 2009 Mintek installed the FloatStar? advanced flotation stabilization system on Vale's Cauê iron ore beneficiation plant in Brazil. In September 2010 the system was upgraded to include flotation optimization. The circuit consisted of two parallel cleaner circuits producing final concentrate. The tailings from the cleaner section passed through a scavenger circuit. Large, well-instrumented feed sumps played an important role in circuit stability, presenting a good opportunity for advanced control. Previously the plant was controlled using distributed control system (DCS) level control only. The flotation circuit processes roughly 30kt/day. The FloatStar system provided advanced control of the flotation circuit as well as of the sumps feeding the circuit. The system underwent a lengthy trial to assess the benefit that it provided. Two data sets were analysed, showing performance under advanced stabilization and optimization respectively. Several validation and consistency criteria were employed to ensure the quality of the analysis. Iron recovery and iron tailings grade were used to measure system performance. The analysis showed that the system increased recovery by up to 2.7%. In addition, the system decreased the iron tailings grade by between 1.2% (from 23.5% to 22.3%) and 4.3% (from 31.3% to 27.0%) during different test campaigns. The analysis also showed that the entire FloatStar stabilization system was active for 72.7% of the time from first activation to the end of the first data set (approximately 200 days). From the analysis it was concluded that under similar conditions for 'ON' and 'OFF' tests, the system provides a clear benefit. It was also found that over the longer term, the system continues to provide a benefit. This finding suggests that the results were not simply due to a short-term advantage. The size of the data set, as well as the magnitude of the recovery improvements, lends considerable confidence to these results. Therefore, it can be concluded that the FloatStar control system provides substantial benefit to operations at this site.

Jan 1, 2012

By Robert G. Ditchburn

The NW caldera hydrothermal vent field at Brothers volcano, of the Kermadec-Tonga arc, has associated massive sulfide mineralization. This includes an abundance of black smoker chimneys that contain significant concentrations of copper, lead, zinc and gold (de Ronde et al., 2005; de Ronde et al, 2010, under review). [ ] The oldest volcanic massive sulphide (VMS) samples recovered so far from Brothers have been dated using radiometric methods at GNS Science and found to be c. 1000 years old. By contrast, a volcanic cone that has formed in the southern part of the caldera has no associated VMS. Only elemental sulphur and Fe-oxide crusts are present here, samples of which have been analysed for their trace elements. From d34S values of sulfates and native sulfur, and the volume of gas (dominated by CO2 and H2S) discharging at the cone site, elements being deposited here are considered more directly magmatic in origin (de Ronde et al., 2005; 2010 under review). It has been discovered that deep-seated changes in volcanic activity at Brothers affect the NW caldera and cone site simultaneously, though the mineralogy at each site is so very different. Thus, the cone site is being studied to determine if elements being deposited there can be used as predictors of potential future VMS mineralisation as similar sites have been found at other volcanoes along the Kermadec arc and elsewhere. The frequency of these deep-seated magmatic events is considered important in the formation of Cu-Au-rich mineralization along arcs. The analysis of Fe within resulting hydrothermal plumes (surveyed by surface vessels), and trace elements in rock and mineral samples, are used to help determine the influence of magmatic contributions to the hydrothermal system. To verify that plumes are a reliable proxy for hydrothermal events depositing iron on the seafloor, Fe-oxide crusts from Brothers volcano cone have been dated to see if their emplacement coincides with highly Fe-enriched plumes in the water column. The radiometric dating techniques developed for barite-rich VMS, i.e. using 228Ra and 226Ra, were unsuitable for the Fe-oxide crusts because 210Pb was the only isotope detected by gamma spectrometry. Therefore, new techniques using 210Pb, 10Be and arsenic have been established.

Jan 1, 2010

By John B. Gustavson

This paper describes a case history of geochemical prospecting. An area of known mineralization was available for an orientation survey which led to the selection of elements and criteria for a reconnaissance survey in the area offsetting the known mineralization. Certain anomalies were found which were then made subject of confirmation sampling and of rock geochemical investigations. Inasmuch as the geochemical prospecting technique specifically led to a detailed area which now serves as a target for drilling and other exploration efforts, the geochemical prospecting part of the program is considered successfully concluded and, therefore, reported on here. Whether the target area will turn out to host the deposit or not is, of course, of utmost importance to the Company, but is of less importance to this paper. We will describe the concepts, the planning, the execution, the analysis and the interpretation of this typical geochemical prospecting case. A number of people on the staff of International Oil & Gas, Inc. have participated in this prospect, as have students from Southeast Missouri State University and their professor, Gary M. Lowell. In addition, the Missouri Geological Survey has been most helpful with records and letters on the century-old prospecting and mining in the general area. Many valuable discussions have also been held with geologists from the industry who, from time to time, have visited the area, examined the property and reviewed the status of the project. The support and interest from all these parties has made it possible to pursue and expand this exploration concept from one of being just "more of the same kind" to the most chal-1enging and exciting with which this author has ever been involved, namely the prospect for tin porphyry deposits in the mid-continent United States.

Jan 1, 1977

By J. E. Dreier, R. E. Scheffel, A. Guzman

"This paper outlines a comprehensive, cost-effective testing program for the acid-ferric sulfate heap leaching of oxide, supergene and primary copper ores. It is based on extensive experience in copper heap leaching and uses the many technological advances in the field developed over the past several decades. The approach described requires firstly a detailed resource evaluation, then a hydrodynamic characterization of representative samples and, finally, a focused metallurgical testing program. The principles communicated here can be applied to other acid leachable minerals. The program varies considerably from conventional testing in its disciplined, orderly, step-by-step approach, its application of hydrological and chemical principles to leaching, and its reliance on fewer, more tightly controlled column tests. The purpose of the test program is to optimize the financial, time and other resources devoted to the program, while minimizing the financial risks to the development company or companies and the project funding providers. IntroductionThe major goal of any process development testing program should be the successful implementation of the project. With respect to heap leaching, the metallurgical testing program plays a critical role in the larger objective, as described in Scheffel (2013, 2014). McNulty’s series of papers (1998, 2004, 2014) confirm that the success of any project is directly proportional to the extent and quality of the testing program on which the process is designed.Therefore, a key development objective is to conduct a well-focused metallurgical test program. While the primary focus of this paper is copper, the acid leaching of any substance would benefit from a similar approach.This paper addresses primarily the sulfate system, which is compatible with the bioleaching of sulfide minerals. Nicol et al. (2011) described the advantages of the chloride leaching of copper sulfide minerals. United States patents Nos. US 2009/0173188 A1, US 8,597,933 B2 and US2015/0232963 A1, assigned to BHP Chile Inc. and BHP Billiton S.A. Ltd, describe methods for both the oxidative and nonoxidative leaching of primary and secondary copper sulfides. Reyes (2013) and Ipinza and Flaquer (2014) described commercial applications of chloride-based heap leaching. The testing disciplines discussed in this paper will also apply to the development of an acidic chloride leaching system."

Jan 1, 2016

By F. P. Morawski, J. E. Schelske, J. R. Geddes, B. R. Eberts, D. M. Wilson, J. D. Jeffries

"The Griffith Mine is located 200 miles northeast of Winnipeg and is 30 miles south of Red Lake, Ontario. Owned by The Steel Company of Canada Limited and managed by Pickands Mather & Co., it has an annual rated capacity of 1.5 million tons of high-grade iron ore pellets with an analysis of 66.3 per cent iron and 4.5 per cent silica.Development of the mine and construction of the plant got underway in January of 1966 and operations began in February of 1968. The orebodies outcrop on the shore of Bruce lake and run under the lake. The ore in its crude form is a metasedimentary low-grade magnetite and occurs in a highly folded banded formation. The average iron analysis of the crude is 29 per cent and the over-all weight recovery is 32 per cent.In order to mine the portion of the orebody under the lake, the soft varved clay on the lake bottom was hydraulically dredged and a dyke constructed of rock, with till used to provide an impervious seal on the lake side of the dyke, prior to dewatering.Mining is carried out by conventional open-pit tech-niques. Ore dressing is achieved by combining one crushing stage and a two-stage grinding system, with beneficiation by magnetic separation, hydroseparation and flotation. Agglomerating is done with conventional balling drums and pelletizing is carried out in shaft furnaces.Of interest and discussed in detail are the 32-foot autogenous cascade mills ."

Jan 1, 1970

By Alvinus Brown Wood

THE ancient copper-mines of Lake Superior, having been destroyed or covered by-modern mining-dumps, are not accessible to the present inhabitants of that region, and, since no more are likely to be found, some account of those already discovered, from one who has seen them, may be acceptable to the Institute. Early in May, 1855, 1 took a party of men to open an ancient pit on the Quincy mine-location. Mr. C. C. Douglas was the Agent.," as mine-managers were then called on Lake Superior. The Quincy Co. had previously done work on a fissure-vein, several hundred feet west of the Amygdaloid lode (afterwards called the Pewabic lode), on which was the ancient pit herein described. It was at this pit that the Quincy' main shaft was subsequently stink. The ancient pit showed an apparent depth of about 4 ft., but when cleaned out it was shown to be 14 ft. deep, having been filled up by the sliding-in of material composed largely of broken rock, taken out in sinking the ancient shaft, and left near its mouth. Midway of the shaft, and below water-level, was found a scaffolding, of white-birch poles,- which had been used as a landing, to assist in removing the excavated rock. The shaft was 7 ft. in diameter. The excavation had been done by first building fires in order to disintegrate the rock, as was proved by the abundance of charcoal found; then breaking the softened rock with hammers of diorite, such as is found in the greenstone range on Keweenaw point. These hammers had about. the size of large paving-stones. Only broken ones were found, the whole ones having been doubtless carried away for other work, such as could be traced on the lode for a hundred feet or more to the south. At the place where this shaft was stink, barrel-copper (i.e.,

Mar 1, 1906

By Errol D. Sehnke

This U.S. Bureau of Mines report provides detailed information on worldwide alumina production capacity by plant and country. The information was compiled from a variety of domestic and international sources and was based on information available to the Bureau through December 31, 1993. Capacity data represent announced installed and planned capacities and do not necessarily reflect a Bureau of Mines judgment of actual plant operating levels or timing of planned expansions, The year-end capacity is the ?nameplate" capacity or estimated production capacity, whichever is larger.

Jan 1, 1993

By George H. Bodfish

This paper begins with a short history of air compressors, emphasizing their "roots" in the mining industry. It then describes the types of compressors available, including reciprocal, the various rotary positive-displacement compressors, and the centrifugal. The advantages and disadvantages of selecting a certain type of compressor over another are enumerated, considering customer requirements and operating costs, among other factors. Guidelines to operation and maintenance are discussed, including installation, monitoring and maintenance procedures. Finally, the paper addresses itself to future trends, with special attention being given to the system concept, the increasing use of rotary compressors, power consumption, reliability, packaging and noise attenuation.

Jan 1, 1978

By Frank Rausche

The more widespread use of Augered Cast-in-Place (ACIP) Piles has generated increased demand for improved quality control measures. These deep foundation elements are often relatively long and slender and their structural quality depends on the experience of the installers, the adequacy of their drilling and pumping equipment, and of course, the properties of the soil. Since the concrete of ACIP piles is pumped under pressure into the borehole, the piles may achieve a very high unit shaft resistance if conditions are favorable and the piles are well constructed. Three types of methods can help assure that the piles are properly executed. During construction, monitoring the volume of concrete pumped and the pressure applied helps avoid structural defects. After installation, and once the concrete has hardened, the Pulse Echo Method allows for a check of the structural integrity of the shaft. Finally, a load test, performed some time after installation, yields a check of both bearing capacity and structural integrity of an individual pile. Because of their expense and associated construction delays, static load tests are normally done for only a few piles. However, at large construction sites, it may be necessary to perform many load tests either as a planned construction control activity or as a means of spot checking or verifying suspect piles. For smaller sites, however, static load testing may be prohibitively expensive. In such situations, dynamic load testing, originally developed for driven piles, has frequently been employed for drilled shafts and ACIP piles. In the latter case special consideration must be given to the ACIP pile slenderness and their often relatively low concrete design strength, which may not tolerate high dynamic loading stresses even though their unit resistance along the shaft is relatively high. Lately, the dynamic load test has become more feasible with the availability of loading systems that are custom tailored to this particular pile type. These systems produce a low velocity, low stress and high energy impact. Recent developments have also made the instrumentation process simpler: force measurements are now made on the ram rather than on the pile for increased reliability and simplicity. This presentation describes the requirements for successful dynamic load testing of auger cast piles and summarizes results from several projects where the new loading system and newly developed instrumentation was employed. A few cases are presented correlating static load test results with dynamic predictions, calculated by CAPWAP®.

Jan 1, 2001

By J. P. McCluskey

The effects of air quality regulations passed in the last few years have been felt in a more pervasive way by the electric utility industry than by perhaps any other industry. I'm referring especially to those regulations dealing with the control of air emissions from stationary sources, and those specifying the quality of fuel used. Particularly, I would like to describe some of the effects that these regulations have had on the Commonwealth Edison Company. To put the subject into perspective, a brief descrip¬tion of the company will be presented first. Then, a historical outline of some of the efforts at control of electric generating station emissions will be described. Following this will be an indication of the Company's response to early State and local regulations prompted by the growing pressure for stringent envi¬ronmental control. Finally, the Company's plans to achieve com¬pliance with the most recent, Federally approved, State of Illinois regulations will be summarized.

Jan 1, 1973

By D. M. Soboroff

Etchants containing hexavalent chromium and sulfuric acid are used in a variety of surface-finishing operations. When the resultant spent solutions are discarded, substantial quantities of chromium are lost and pollution prob¬lems are created. To minimize the undesirable environmental effects while improving metal and minerals recycling technology, the Bureau of Mines is conducting research on a method for the economic inplant recycling of these waste etchants. Trivalent chromium, produced when the etchant reacts with a sub¬strate, is oxidized in the anode chamber of a diaphragm cell; other metals, dissolved during the etching operation, are transferred to the catholyte. When waste brass etchants are treated in this manner, all of the trivalent chromium is oxidized and more than 40 percent of the copper and zinc is removed. Similar copper removal and chromium oxidation are achieved with waste printed circuit board etchants and rinse waters from plastic etching operations. The electrical energy needed to regenerate 1 kg sodium dichromate is less than 9 kwhr. Regenerated brass etchants evaluated by two companies equaled or exceeded the performance of fresh etchants.

Jan 1, 1979

By Osvaldo A. Bascur

Most mining and metallurgical plants have developed predictive maintenance policies based on statistical analysis and special techniques, like vibration analysis, oil and lube analysis for critical equipment. Process control strategies have also been installed in several metallurgical sites. These control strategies require instrumentation maintenance from local personnel. The availability of real time and process history to identify the most critical part of the processing system from mechanical integrity is a must for global plant optimization. Specialized performance control monitoring algorithms are required to justify their existence and contribution to the bottom line. Emerging technologies are combining these techniques into a single total plant system. Tools are required to assist in troubleshooting and adapting these process control instruments and strategies. The key is the plant equipment and process control availability and utilization rather than just maintenance.

Jan 1, 1997