Search Documents

By D. M. A. Flight, P. M. Green, J. A. Plant, P. R. Simpson

Paper presented at Mineralisation in the Caledonides, the Mike Gallagher memorial meeting held in Edinburgh, 27-28 June 1996. The British Geological Survey's regional geochemical database is used to identify the patterns associated with the various mineral deposit types and to examine the extent to which their distribution reflects the presence of long-lived metallogenic provinces in the crust. Image analysis provides new insights into the setting of the mineralisation, geochemical constraints on tectonic models of Caledonide evolution and evidence for terrane amalgamation and large-scale processes. There is evidence that much of the mineralisation reflects the presence of long-lived provinces with a distinctive geochemistry reflecting their origins as zones of crustal extension. In the case of the Middle-Upper Dalradiam sedex deposits, the relationship between geochemistry and tectonic setting is direct. In other cases, rocks deposited in extensional zones appear to have acted as reservoirs of ore-forming elements which were further concentrated during later events

Jun 19, 1905

By R. Shimpo

Equilibrium calculations by a computer may sometimes fail in giving solutions when the system includes a large number of components and more than three phases, and especially when no definite information about stable phases is given. An improved method of calculation is presented in which the number of phases need not to be initially fixed, phases can appear or disappear in the course of' calculation and a new method is combined with the Newton-Raphson method to obtain solutions easily. The improved method is applied to the copper smelting operation and all the successive stages of the operation are successfully simulated.

Jan 1, 1983

Pipe Flow Stability of Concentrated Coal-Water Suspensions in the Presence of an Electric Field

Sep 13, 2010

By B. T. Brady

Recent theoretical, experimental, and field studies conducted by the Bureau of Mines suggest that rock failures may be predicted and, in some instances, controlled. Theoretical studies that were later corroborated by laboratory and field studies predict that a seismic anomaly will precede rock bursts and/or roof falls in mines. The seismic anomaly is predicted to consist of an increase in the number of seismic events occurring in the immediate vicinity where the failure 1s nucleated. This increase will then be followed by a dramatic decrease of seismicity in a broad region that surrounds the location of the impending failure. The dimensions of this region allow a preliminary estimate of the time to failure (measured from the time the seismicity increase began) as well as an estimate of the energy that will be released at the instant of failure. Field observations indicating that this predicted behavior does precede rock bursts and a roof fall are presented in this report. Implications of results to the problem of failure control in mines that experience massive rock failures are discussed.

Jan 1, 1978

By A. J. Farstad

Characteristics of metal/non metal mines were evaluated to determine the suitability of applying the U.S. Bureau of Mines electromagnetic location system to the problem of locating trapped mines in metal/non metal mines. Statistical distributions of mine depths and overburden conductivities show that the existing USBM EM system is inadequate for most metal/non metal mines. Alternate approaches to trapped miner location in deep mines were identified and subsequent field tests were conducted at six (6) mines to evaluate their feasibility. The approach considered to be the most promising is one which utilizes the existing manpack transmitting system, modified slightly for a dual frequency output, in conjunction with a sophisticated signal processing receiver on the surface. The main advantage of staying with a "through the earth" approach is that the underground equipment can be kept simple, easily maintained, light-weight and inexpensive.

Jan 1, 1979

By Pengfu Tan

Electric arc furnace (EAF) dust from the steel industries is listed by the United Sates EPA as a hazardous waste under the regulations of the Resource Conservation and Recovery Act due to the presence of lead, cadmium and chromium. The disposal of the approximately 650,000 tons of EAF dust per year in the U.S. and Canada is an expensive and unresolved problem for the majority of steel companies. The Waelz process has been considered as the best process for treating EAF dust. A process model, combined thermodynamic modeling with heat transfer calculations, has been developed to simulate the chemical reactions, mass and heat transfer and heat balance in the kiln. The injection of air into the slag and the temperature profile along the kiln has been modeled. The effect of (CaO+MgO)/SiO2 on the solidus temperature of slag has been modeled also and discussed. Some optimizing results have been presented in this paper.

Jan 1, 2005

By Robert McClure

The detection, recovery and disposal of commercial explosives and explosive waste has always carried a level of risk and requires specialized equipment and technical expertise. Improperly stored, discarded, deteriorated, misfired, stolen or surplus products are often the primary sources of explosives that require safe disposal. Detection and disposal tools available today have advanced significantly due to developments in Counter-Improvised Explosive Devices (C-IED) operations and commercial blasting technology. These technologies have provided safer more efficient ways to detect, investigate and dispose of commercial explosives products in order to minimize property damage and potential harm to disposal personnel and the general public.

Jan 1, 2015

By Zhigao Xu, Ming Wu, Jun Qu, Rong Zhang, Wenrui Nie, Ruan Chi, Zhenyue Zhang, Zhengyan He

The leaching processes and mechanisms of weathered crust elution-deposited rare earth (RE) ores with ammonium sulfate were investigated for their high efficiency and low consumption exploitation. The leaching process is a typical reversible heterogeneous ion exchange reaction in liquid–solid systems. The raw ore and leached tailings were analyzed by SEM and FTIR. Results indicated that no dissolution or structural changes of the ores occurred during the leaching process. The migrations of RE3+, Al3+, and NHþ 4 in the leaching process were studied under various liquid–solid ratios. With increasing liquid–solid ratio, the content of NHþ 4 adsorbed on clay mineral by physical effect decreased, NHþ 4 adsorbed by ion-exchange increased, and the content of exchanged RE and Al increased until reaching equilibrium. The adsorption capacity of the RE ores for NHþ 4 remained about 0.61–0.63 mg/g. It was difficult to desorb NHþ 4 from RE ores with washing water alone. The leaching mechanism of Al was the same as RE, but the leaching of Al slightly lagged behind RE. At the optimal liquid–solid ratio of 0.4:1, the leaching efficiencies of RE and Al were 95.51% and 90.99%, respectively, and 56.65% of NHþ 4 remained in the leachate. After impurity removal and RE precipitation, the leachate can be reused by replenishing fresh leaching agent. The aim of this study is to enhance the leaching process of RE, restrain the leaching of impurities, and decrease the consumption of leaching agents.

By Zhigao Xu, Ming Wu, Jun Qu, Rong Zhang, Wenrui Nie, Ruan Chi, Zhenyue Zhang, Zhengyan He

The leaching processes and mechanisms of weathered crust elution-deposited rare earth (RE) ores with ammonium sulfate were investigated for their high efficiency and low consumption exploitation. The leaching process is a typical reversible heterogeneous ion exchange reaction in liquid–solid systems. The raw ore and leached tailings were analyzed by SEM and FTIR. Results indicated that no dissolution or structural changes of the ores occurred during the leaching process. The migrations of RE3+, Al3+, and NHþ 4 in the leaching process were studied under various liquid–solid ratios. With increasing liquid–solid ratio, the content of NHþ 4 adsorbed on clay mineral by physical effect decreased, NHþ 4 adsorbed by ion-exchange increased, and the content of exchanged RE and Al increased until reaching equilibrium. The adsorption capacity of the RE ores for NHþ 4 remained about 0.61–0.63 mg/g. It was difficult to desorb NHþ 4 from RE ores with washing water alone. The leaching mechanism of Al was the same as RE, but the leaching of Al slightly lagged behind RE. At the optimal liquid–solid ratio of 0.4:1, the leaching efficiencies of RE and Al were 95.51% and 90.99%, respectively, and 56.65% of NHþ 4 remained in the leachate. After impurity removal and RE precipitation, the leachate can be reused by replenishing fresh leaching agent. The aim of this study is to enhance the leaching process of RE, restrain the leaching of impurities, and decrease the consumption of leaching agents.

By Arash Maghsoudloo, Asli Can

"Abstract This paper presents a ground improvement implementation case under a raft foundation of a local hospital. The selected ground improvement method is Wet Soil Mixing (WSM) technique. Soil mixing is increasingly applied to environmental applications and ground stabilization in geotechnical projects. In this technique, weak soil is mixed with cementitious slurry to improve the characteristics of the soil. The investigated case is one of the pioneering WSM ground improvement technique implementation cases in Turkey. The soil profile is mainly consisted of low plasticity clay. The effect of ground improvement is verified by a series of laboratory tests and four in-situ pile loading tests. The results of in-situ pile load tests on constructed soilcrete columns showed an acceptable factor of safety for the bearing capacity of the WSM columns. Measured bearing capacities in all four tested columns were nearly 20% higher than calculated values. In addition, a set of samples are obtained from the constructed columns and unconfined compression tests have been conducted. The laboratory test results indicate that the selected cementitious slurry has a sufficient efficiency to form the stabilizing columns.IntroductionIn the construction industry, stabilization of the soft ground by lime or cement stabilization is a widely used technique. In ground improvement systems deep mixing method (DMM) results in the same stabilization in deep portions of the soft soil profile by mixing cementitious slurry by means of mechanical augers. The pioneering cases of modern deep mixing application can be traced back to the year 1970 that was used for the stabilization of marine soils below the water level for the construction of harbor structures (Terashi et al., 1979). Nowadays, DMM is shown to be a proper and efficient method for the foundation of the structures and embankments on land. Some recent studies also reported that reasonable settlement reduction range in the stabilized soils under the foundation of structures (Archeewa et al., 2011). In addition to reduction of the structural settlement under service loads, deep mixing methods are also utilized when there is a concern with contaminated soil and groundwater or groundwater control (Andromalos and Bahner, 2003).Although, the DMM is shown to be a successful method in numerous studies for improvement of a wide range of soil types such as organics, fine-grained, and coarse grained material, it has some limitations (Archeewa et al. 2011, Jameson et al. 2010, Jelisic and Leppanen 2004, Lambrechts and Roy 1997, Meyersohn 2007, Miki and Nozu 2004, Olsson et al. 2008, O’Rourke and McGinn 2004, Stewart et al. 2004, Yang et al. 2011). High soil density and stiffness could damage deep mixing rigs. Engineering properties of the soilcrete columns changes based on the soil type, water content and other factors such as organic content of the available soil profile, so properties of the generated soilcrete should be verified by a set of rigorous testing procedures (Puppala et al. 2004).Based on the general classifications presented in the ground improvement literature, deep soil mixing method is divided into two main types of dry or wet mixing methods. In the dry and mixing methods compressed air and water are utilized as the binder transporter medium respectively (Moseley and Krisch, 2004). In addition, DMM methods can be categorized based on the employed mixing methods during the construction. In this study, the main aim is to present and elaborate on the selected method is known as Wet Speed Soil Mixing (WSSM)."

Jan 1, 2014

By PAUL L. FISHER

This bibliography has been compiled by the Bureau in answer to many requests now being received for information on the briquetting coal and other carbons . In addition to publications issued by the Government in printed or mimeographed form, references are included to articles appearing in the technical press and in cooperative reports of work done jointly with states , colleges , and industries . References and patents are arranged in chronological order . Bureau of Mines bulletins , technical papers and Minerals Yearbooks are printed , and are obtainable from the Superintendent of Documents ,. Government Printing Office , Washington 25 , D. C. Reports of investigations , information circulars , and the directories and reports of the mineral industry surveys are published in mimeographed form and may be obtained without charge from the Publications Distribution Section , Bureau of Mines , 4800 Forbes Street , Pittsburgh 13 , Pa . Many Bureau of Mines publications , as well as bound copies of the foreign and American scientific and trade periodicals , may be consulted in technical , college , and large public libraries throughout the country. Dealers in new and second-hand books sometimes have copies of these reports for sale .

Jul 1, 1948

By Fred N. Kissell

This handbook describes effective methods for the control of mineral dusts in mines and tunnels. It assumes the reader is familiar with mining. The first chapter deals solely with dust control methods, regardless of the application. It is a brief tutorial on mining dust control and will be of help to the reader whose dust control problem does not conveniently fit any of the mining equipment niches described in later chapters. The subsequent chapters describe dust control methods for different kinds of mines and mining equipment. This includes underground coal and hard-rock mines, as well as surface mines, stone mines, and hard-rock tunnels. Because dust sampling has so many pitfalls, a chapter on methods used to sample dust is included. For those occasions when there is no practical engineering control, a chapter on respirators is also included. Except for those listed as ?future possibilities? in the longwall chapter, the dust control methods described are practical and cost-effective for most mine operators. If controlling dust were a simple matter, dust problems in tunnels and mines would have been eradicated years ago. Unfortunately, most underground dust control methods yield only 25% to 50% reductions in respirable-sized dust. Often, 25% to 50% reductions are not enough to achieve compliance with dust standards. Thus, mine operators must use several methods simultaneously, usually without knowing for sure how well any individual method is working. In fact, given a 25% error in dust sampling and day-to-day variations in dust generation of 50% or more, certainty about which control methods are most effective can be wanting. Nevertheless, over the years, some consensus has emerged on the best dust control practices. This handbook summarizes those practices.

Jan 1, 2003

By D. Earley

High metal prices and new world trade standards and accounting for environmental liability in financial disclosures are creating markets for metals commodities that are produced using ?green technologies?. A promising "green" gold leaching system uses a polysulfide based lixiviant which is non-toxic and non-polluting. Laboratory testing has demonstrated selective gold extraction rates comparable to those of cyanide. The polysulfide lixiviant is a dilute aqueous solution which can be inexpensively produced from readily available chemical reagents and even mining wastes. The reagent system is self-buffering and maintains the optimal chemical environment for leaching. Treatment of residual leach solutions is not necessary because the lixiviant itself is not toxic, and breaks down as the system equilibrates. Simple closed system boiling is used to recover gold from process solutions. The polysulfide lixiviant can then be readily renewed and recycled back into the system, forming a closed loop system that conserves reagents and energy which minimizes operating costs. Economic projections have shown that the system can be used profitably for standard ore types and grades.

Jan 1, 2009

By Yousef Ghorbani, Abolfazl Danesh, Fatemeh Kazemi, Ataallah Bahrami, Morteza Abdollahi, Mohammad Raouf Hosseini

This study aims to investigate the effects of operational variables on concentrate grade, recovery, separation efficiency, and kinetic parameters of the copper flotation process. For this purpose, the effects of the pulp solids content, collector and frother dosage, and preparation and concentrate collection time were studied using a Taguchi experimental design. The results of statistical analyses indicated that the concentrate collection time and pulp density were the most influential parameters on concentrate grade. Considering copper recovery, concentrate collection time, collector dosage, and pulp density were the most significant variables, in decreasing order of importance. Also, the separation efficiency was mostly influenced by the concentrate collection time. Furthermore, kinetic studies showed that the second-order rectangular distribution model perfectly matched the experimental flotation data. The highest kinetic constant of 0.0756 s−1 was obtained from the test, which was performed with 35% solids content and 40 and 20 g/t collector and frother, respectively. The highest predicted copper recovery of 99.57% was obtained from the test at 30% solids content, and the collector and frother dosages of 40 and 15 g/t, respectively

Support design in jointed or blocky rock masses is often approached by the use of either 'rules of thumb', rock mass classification systems such as the Q-system (Barton, Lien and Lunde, 1974) or RMR (Bieniawski, 1973) or conventional wedge analysis. Generally, this requires that a number of key simplifying assumptions are made and the support system is designed to cater for either a mean, most likely, or worst case scenario depending on the risk tolerance. The design block size is often a major uncertainty and often a worst case block size based on excavation span is used. Thompson and Windsor (2007) state that it is inappropriate to base support designs on the excavation size as these size blocks rarely occur if discontinuity trace lengths are considered. Probabilistic keyblock methods can be used to determine the most likely design block sizes. A methodology is presented whereby JBlock software (Estherhuizen, 1996) is used to estimate potential block sizes as part of the support design process. Using information such as the spacing, orientation and length of discontinuities, it is possible to simulate blocks in the walls of an excavation (Esterhuizen and Streuders, 1998). Keyblock analysis methods (Goodman and Shi, 1985) are used to evaluate whether blocks are removable and whether the chosen support will be sufficient to ensure stability. Data from two mines is used to demonstrate how probabilistic keyblock analyses can be used in support design. Discontinuity data was used to generate 10 000 removable blocks and the design block size statistics were determined. For one mine this information was used to scale blocks in a conventional. Unwedge analysis whilst for the other mine, the point estimate method (Harr, 1987) was applied. The choice of appropriate design acceptance criteria in terms of factor of safety and probability of failure is also considered.

Nov 25, 2010

By R. Altindag

Engineers and researchers need to estimate the mechanical properties of rocks from P-wave velocity. In previous studies, the researchers have investigated either the limited values or all the data belonging to sedimentary, igneous, and metamorphic rocks together in the same statistical analysis. In this study, the raw data pertaining to only sedimentary rocks was taken from previous studies and evaluated. For this purpose, a total of 97 samples of sedimentary rock types were subjected to statistical analysis. First, the relationships between P-wave velocity and physical-mechanical properties were investigated by simple regression analysis. All the data were then subjected to multi-regression analysis. Some empirical equations with high correlation coefficients were derived for rock engineers. The equations obtained from the analyses are compared with previous equations found in literature.

Jan 1, 2012

Advances in Optical Image Analysis and Textural Classification of Iron Ore Fines

Sep 13, 2010

By Martin Plante, Denis Hamel, Marie-Pier Bédard, Jeff McLaughlin

"The results and methodology for the optimisation of the zinc flotation circuit at the Matagami Mill using the 6-Sigma methodology are shown in detail while only the base line and final results are presented for the copper circuit. As a result of the six sigma project, the zinc concentrate grade was improved by 2% and the zinc recovery by 3%, with reduced dosage of reagents while the copper concentrate was improved by 2.4%. The process variation in the zinc concentrate grade and recovery was also reduced by over 50%. The main factors contributing to the project success were identified to be improvement in the plant measurement systems, an internal benchmarking exercise and statistically designed laboratory and in plant tests to guide the process improvement. The annual value to Noranda resulting from this project has been estimated at approximately $5 million.INTRODUCTIONThe Matagami concentrator started ore processing from the new Bell- Allard deposit in July 1999. Concentrator performance (grade and recovery of zinc and copper concentrates) was highly variable and work was ongoing to fix the sources of variation. In the mean time, Noranda embarked on its 6-Sigma initiative across the company. The 6-Sigma DMAIC (Define, Measure, Analyse, Improve, Control) methodology was used in the two flotation circuits to reduce variation and improve performance. The statistical 6-Sigma methodology moves towards identifying and controlling critical process operating variables (the X' s) to achieve customerspecified performance (the Y's). The goal of the methodology is to describe a process in a numerical equation known as the transfer function, given as Y = f (XI, X2, X3.. .), where Y could be concentrate grade or recovery and examples of X's are reagent dosage, particle size, etc. With the transfer function, optimal operating conditions and control tolerances are established for the key X's to ensure the desired Y performance is obtained.Each phase of the 6-Sigma methodology is explained below with examples from the Matagami project."

Jan 1, 2001

This Bureau of Mines publication presents five papers given at a Technology Transfer Seminar on Metal Mine Fire Protection Research. Several seminars are held each year to bring the latest results of Bureau conducted and sponsored research to the attention of the mining industry as quickly as possible.

Jan 1, 1977

By W. H. Langer

At the start of the 20th century Denver?s population was 203,795. Most streets were unpaved. Buildings were constructed of wood frame or masonry. Transport was by horse-drawn-wagon or rail. Statewide, aggregate consumption was less than 0.25 metric tons per person per year. One hundred years later Denver had a population of 2,365,345. Today Denver is a major metropolitan area at the crossroads of two interstates, home to a new international airport, and in the process of expanding its light rail transit system. The skyline is punctuated with skyscrapers. The urban center is surrounded with edge cities. These changes required huge amounts of aggregate. Statewide, aggregate consumption increased 50 fold to over 13 metric tons per person per year. Denver has a large potential supply of aggregate, but sand and gravel quality decreases downstream from the mountain front and potential sources of crushed stone occur in areas prized for their scenic beauty. These issues, along with urban encroachment and citizen opposition, have complicated aggregate development and have paved a new path for future aggregate development including sustainable resource management and reclamation techniques.

Jan 1, 2009