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By Li Qian

Mechanisms of bio-dephosphorization from iron ore was investigated in this Paper. The results show that there are two bio-dephosphorization ways from iron ore, the one is that Acidithiobacillus ferrooxidans directly derive phosphorus from the ore, the other is phosphorus is able to be leached acid produced during metabolizing of Acidithiobacillus ferrooxidans, and the latter is more important than the other. Adding suitable pyrite can enhance the bio- dephosphorization process through providing nourishment and producing acid directly due to S 3oxidized or indirectly due to Fe3 as oxidant. The potential varies in the range of 0.434~0.498V and pH is in the range of 2.5 ~ 1.25 during bio-leaching process. It can be founded that, according 2+to the E-pH graph of Fe-H2O system, Fe wouldn?t be oxidized under sterile system in this potential and pH ranges. It can be obviously concluded that the Acidithiobacillus ferrooxidans are 2+able to reduce the potential for the oxidization of Fe and make the oxidization occur in the above pH and potential zone, so the bio-leaching process can proceed. the investigation of E-pH graph of P-H2O system show that H3PO4 can exist steadily.

Jan 1, 2009

By M. C. Harris

Float-sink analysis has wide application in the coal laboratory. This paper evaluates the established methods used for the float-sink analysis of fine coal, and then describes a new method and apparatus that can be used for material down to a few micrometres in size. The method is rapid and accurate, and requires only a small amount of sample. The results presented show close agreement with the float-sink analyses obtained by the more classical technique using separating columns. The new centrifugal method reduces the time required for the analysis by a factor of ten.

Jan 1, 1986

By K. Verghese

Neutron capture prompt gamma-ray analysis provides the best method for on-line analysis of the elemental composition of large volumes of bulk material. This paper summarizes the Monte Carlo models which simulate the radiation transport within two such analyzer systems; namely, the borehole configuration and the conveyor belt configuration. The models are useful in the design optimization of the analyzer systems, in minimizing the amount of experimental calibration data for calibrating these analyzers, and in investigating the detection sensitivity for different elements. The computational scheme in these models is made extremely efficient by the use of various powerful variance reduction methods and by efficient data management. Experimental verifications of the two models carried out in the laboratory indicate very good agreement with the Monte Carlo results.

Jan 1, 1984

By J B. Pateiro-Fernßndez, M Fuchsschwanz, G Deissmann, S Ahmad

Quang Ninh province is the most significant coal producing region in the north of Vietnam. The Nui Beo Coal Company (NBCC) operates open pit mines in Quang Ninh province and the waste overburden produced is dumped as sidehill fill in the Chinh Bac waste dump site. In the past, no special consideration has been given to the environmental impacts during the dumping operations. The mine waste is transported in trucks from the mine site to the dumping site and the loading, hauling and dumping operations are the main sources of dust emission. Rain events, especially during the rainy season, cause the generation of contaminated surface water as well as seepage of water through the dump at a number of locations. The existence of cracks at the top of the dump can pose serious stability problems with heavy rain events leading to failure of slopes which can potentially disturb vast areas of land currently used for agricultural purposes and human settlement. For sustainable development at the Chinh Bac waste dump site in the future, apart from the social and economic considerations to be assessed, there is an absolute necessity for environmental protection measures to be in place both during and after the dumping of the mine waste overburden. Research Association Mining and Environment in Vietnam (RAME) is working to develop and implement concepts for the mitigation of environmental problems emerging from dust, contaminated water and lacking slope stability to ensure successful rehabilitation of the coal mine waste dumps in the north of Vietnam. Within the framework of RAME, the Institute of Mining Engineering I (RWTH Aachen University) is managing and working to develop the stabilisation concepts for the solid mine waste dump in collaboration with the Chair of Geotechnical Engineering (RWTH Aachen University), Brenk Systemplanung and the Vietnamese group of companies VINACOMIN (Vietnam National Coal-Mineral Industries Group). The most economical and environmentally sound operations, as well as locally adaptable environmental protection measures, are essential for the sustainable development of the dumping operations at Chinh Bac dump. This paper describes the dump site and the sustainable development possibilities with an emphasis on the environmental protection and stability problems at the Chinh Bac waste dump.

Jan 1, 2009

By T. J. Kim, S. Suh

The purpose of this paper is to evaluate overall prospects of the export market in the Pacific Rim for Illinois steam coal in terms of recent changes in global socioeconomic factors. To pursue this objective, three factors affecting the prospects of Illinois coal in the Asian market were selected for detailed analysis: quality requirements of imported coal, particularly those of the Japanese market; import controls and regulatory factors; and transportation factors affecting the export of Illinois coal. Based on these analyses, alternative long-term strategies are suggested for promoting Illinois coal export in the Asian market.

Jan 1, 1988

The introduction of new technology into thegold-mining industry has been encouraged in recent years by increases in the price of gold andthe necessity for costs to be contained.At most new gold mines, run-of-mine millingis preferred over crushing and multistage milling, and this change at the head of the circuit leaves no place for the manual sorting of ore and for gravity concentration in the mill circuit.Flotation continues to hold its place in goldrecovery. However, a decline in the demand forsulphuric acid may limit the amount of pyrite thatcan be roasted before cyanidation.

Jan 1, 1984

By C. Frenzel

Tunnel boring machines (TBM) utilize disc cutters as the primary means for excavating hard rock. Depending on rock excavatability and rock abrasivity disc cutters can exhibit significant wear. A detailed analysis has been carried out to characterize failure modes and wear patterns of disc cutters. The relationship between rock properties, op-eration of the TBM, and failure modes of cutting tools is clearly high-lighted. On that basis a prediction tool for disc cutter consumption has been developed that allows to estimate not only gross cutter life, but accounts for cutterhead design, premature cutter changes, and disc cutter repair costs.

Jan 1, 2011

By Larry H. Heflin

The Washington Metropolitan Area Transit Authority's Wheaton Station and tunnel design was completed and offered for bid in the Spring of 1983. The format was unique to the Authority: a four part, four fiscal year contract developed in response to funding limitations with construction divided into four stages allowing the maximum amount of work to be done each year for the funds available. The bid was based on the entire contract, but was orginally awarded for only the first year's work. Each year's work had a maximum funding limitation thus safe guarding the Authority from a grossly unbalanced bid. The Authority's estimate for this work was $83,871,524. The low bid came in at 61% of this for a total low bid of $51,512,058. The low bidder was ILBAU America Corporation whose home offices are in Austria. Following receipt of the bids (and resolution of objections cited by other bidders who felt that the job could not be done for the $51 Million dollar figure), a Notice-To-Proceed was given on October 5, 1983. The construction contract allows a Value Engineering Change Proposal, called a VECP which is initiated and developed by the contractor to change the drawings, specifications or other requirements of the contract. Among other things the VECP should decrease the contract price while maintaining the service life, reliability, ease of maintenance, and standardized features and appearance and not require an unacceptable extension of the contract time. A VECP must estimate the amount of the net savings

Jan 1, 1985

By E. Wroth, D. G. Krige

Written contribution E. Wroth* (Visitor): The technical aspects of the assistance scheme which IS provided for in the Gold Mines Assistance Act, 1968, and certain consequential amendments to the Income Tax Act, 1962, are explained by Dr Krige. The object of this contribution is to explain the working of the Gold Mines Assistance Act (hereafter referred to as the 'Assistance Act') for the benefit of those concerned with the tax and assistance assessments of gold mining companies. The views expressed do not necessarily reflect the Revenue Department's interpretation of the legal provisions involved. 1. MINES WHICH QUALIFY FOR ASSISTANCE 1.1 The assistance scheme is applied on a selective basis. Mines which qualify for assistance are defined in the Assistance Act as 'assisted gold mines'. The requirements for classification as an assisted gold mine are that: (i) the mine be a producing gold mine; (ii) it would be likely to close down within eight years if not assisted; and (iii) with State assistance its life would be appreciably prolonged and there would be a significant increase in production of gold or uranium, or of both gold and uranium. 1.2 A mine is only considered for classification as an assisted gold mine on application. Such applications must be made to the Mining Leases Board through the Government Mining Engineer. Classification of a mine as an assisted gold mine is at the discretion of the Minister of Mines who acts in consultation with the Minister of Finance and has regard to the recommendations of the Mining Leases Board. 1.3 The Minister of Mines will impose conditions subject to which a mine is to be classified as an assisted gold mine. The most important will be that the mine must immediately lower its operating pay limit, as normally calculated, by a percentage fixed by the Mining Leases Board and conduct its future mining operations in accordance with the average grade of its ore reserves determined on the basis of such lower pay limit. l.4 The Minister will fix the date as from which classification as an assisted gold mine is to be effective. So long as the mine has operated on the basis of the lowered pay limit for at least three months during the particular year of assessment, he would normally fix the effective date as the first day of the year of assessment.

Jan 5, 1968

By J. A. Cervantes

A statistical model for assessing the risk of ground subsidence in abandoned mine areas is presented. The model is based on the relationship that exists between .the frequency and the location-of subsidence events in a given area and the physical conditions of the ground. These conditions can be described by a series of geological, mining, and physical variables. The model suggests the existence of regions in the multidimensional space of variables which are associated .with increases or decreases in the frequency of subsidence events. Regions associated with an increase in the frequency of subsidence events correspond to regions of higher risks, and vice versa. Risk assessment is based on the ability to express the limits of these high and low risk regions in the, space of variables, and on the ability to express the degree of membership of blocks of land within any of these regions. The theoretical framework for the model is extracted, from discriminant analysis. Risk is quantified by the probabilities of membership of blocks of land into any of these regions. Risk maps are produced by displaying membership probabilities in. appropriate contouring levels. The model has been applied in two urban areas where subsidence of the ground has been active in the past. The two areas are Penn Hills, near Pittsburgh, and Scranton/Wilkes-Barre in northeastern Pennsylvania. In this paper, only the results for the Scranton/Wilkes-Barre area are presented. Those for the Penn Hills area have been presented elsewhere (Cervantes, et al, 1990). In the- Scranton/Wilkes-Barre area, geostatistical estimates of variables likely to affect the stability of the ground were made using samples from 53 drillholes. The estimates were made for 2000x2000 ft squared blocks of land covering the study area. Discriminant functions were computed from the estimated variables and used to establish regions for classifying blocks of land into one of these two populations: 1) blocks not likely to have a subsidence event, and ii) blocks likely to have one or more subsidence events. The same, discriminant functions were used to compute membership probabilities for blocks of land to tall within any of these two populations. These probabilities were contoured to produce a risk map. The risk map produced compares well with the location of the subsidence events which have occurred to date in the area.

Jan 1, 1992

By Douglas B. Silver

"Editor’s note: Douglas B. Silver, Portfolio Manager, Orion Resource Partners, was the keynote speaker at the 2017 SME Annual Conference & Expo in Denver, CO on Feb. 19, 2017. He also gave the keynote address to the SME Annual Conference in 2008. The following is his 2017 keynote address with a few of the slides that were presented. The full speech is available on YouTube https://www.youtube. com/watch?v=uF0qwGJIX3UIn 2008, I had the privilege of giving SME’s keynote address. At that time the financial markets were on the verge of collapse and my presentation described the issues. Unfortunately I was correct, and global markets went into a steep nosedive, creating the largest economic downturn since the Great Depression.In hindsight, there were plenty of signs that this was coming. The Supercycle had created massive new wealth. This wealth was largely invested in the United States due to the country’s political stability and credit worthiness. In 2004, the large investment banks convinced the U.S. Securities Exchange Commission (SEC) to allow them to triple their borrowing leverage ratios. This made the banks more vulnerable to market volatility. The banks then lent money to NINJAS - people with no income, no job and no assets. Even worse was the fact that these unqualified home owners used adjusted-rate mortgages (ARMs) which they, of course, intended to refinance prior to interest rates rising. These mortgages were then bundled up by the banks and sold to investors as “safe” investment products. The money flowed into these products because the rating agencies gave these instruments high marks. These same agencies earned their fees from the very same banks seeking high ratings. (No conflict there). Private debt exploded and peaked out in 2008.These mortgage products were sold in an unregulated shadow banking system and the ARMs came due. Toxic mortgage default rates skyrocketed and the mortgage-backed securities collapsed in value. This house of cards had a negative feedback loop that accelerated the market crash and resulted in more than $1.5 trillion being lost in the securitization sector, a 47 percent decline in the Dow Jones Industrial Average, foreclosure rates skyrocketing and housing prices collapsing. The financial markets were in a nosedive."

Jan 8, 2017

By Ryan Ward

The Missouri River Intake Screen Structure and Tunnel (MRISST) is one phase of the Red River Valley Water Supply Project (RRVWSP), a vital piece of infrastructure in the state of North Dakota to transport water to drought-laden communities in the eastern half of the state. The scope of work consists of constructing a cofferdam in the Missouri River, mining a 1,600-foot by 74-inch tunnel from a secant pile shaft near the riverbank into a cofferdam, and erecting a 40-foot Y-shaped vertical pipe structure in the cofferdam to support the intake screens. Construction personnel worked in the river through the North Dakota winter to construct the cofferdam and contended with high hydrostatic pressures and raveling sands, gravels, cobbles and boulders while mining the tunnel. Diligent planning and meticulous execution were essential to overcoming the challenges encountered below the Missouri River.

Jun 13, 2023

By W. M. Kidd

INTRODUCTION Uranium mine inspection in Canada forms one element of the enforcement of the Atomic Energy Control Act; it is under this Act that all Canadian uranium mines and mills are licensed to operate. Inspection duties are carried out by a small core staff of federal government inspectors (working for the Atomic Energy Control Board (AECB)) largely supplemented by provincial mine inspectors working on behalf of the AECB. Unlike most resource extraction in Canada, uranium mining is under federal jurisdiction and consequently it was the AECB who decided in 1975 that changes in the Canadian uranium mining industry, particularly its expansion and the expanding role of the mine inspector in the limiting of exposures, warranted the offering of a special radiation protection training course. The Uranium Mine Inspector Training Course (UMITC) was first conducted in 1976 at the Elliot Lake Centre in Elliot Lake, Ontario. Subscription for the course was not limited to mine inspectors to enable union stewards, management personnel and provincial/federal labour inspectors to attend. This paper will present an outline of the course content, the format of its presentation and non-curriculum aspects of running a course of this type in uranium-producing community. The core lecturers for UMITC are drawn from the Radiation Protection and Uranium Mine Divisions of the AECB. In addition, guest lecturers are invited from universities and medical research centres together with industry professionals and government researchers. In all some twenty-four plus presentations are made over the first five days of lectures. The program topic areas, hazards, controls, measurements, record-keeping and health effects are preceded by an intensive half-day session on radiation fundamentals. TOPICS Hazards [Dust] A review of the dynamics of airborne particles including the effects of particle size, gravity and wake-turbulence on the behaviour of dust clouds. Associated topics are migrational aspects of dust particles and specific dust-generating mine operations. [Radiation] Canadian uranium mines are increasingly diverse in nature ranging from large scale low-grade underground operations in Elliot Lake to smaller high-grade open pits in Saskatchewan. Papers are presented on assessments of internal and external exposure, the metabolic pathways of ingested or inhaled radiation and the specifics of mine and mill hazards. Radiation hazards are further broken down into gamma surveys of uranium mines, radon daughter concentrations and problem areas. Controls The relationship between mining methods and the operating environment is critically important to ensuring safe working conditions. This refers to both the selection of machinery/devices, etc., and to engineering controls which are instituted to remedy problems created by new technology. UMITC examines a number of possible mining techniques, their criteria for selection and impact on the working environment. Control measures, ventilation practices and design, the need for continuous water misting and special open-pit precautions are presented. These lectures frequently conclude with suggestions for better operating guidelines for mine ventilation systems and the need for greater co-operation between the ventilation department and the underground crews. Measurements Uranium mining regulations stress the need for a high standard of exposure monitoring, statistical planning and record-keeping. [Statistics] Although many course participants are well versed in statistics, certain fundamentals are repeated and include, the concepts of mean, variance, standard deviation and standard deviation of the mean. Confidence levels, decision-making based on sample statistics and statistical records are also discussed. [Dust Measurement] Dust measurement is particularly critical in the mines where the high silica content of the ore body, such as those at Elliot Lake, results in the continuous generation of dust. Sampling practices, filtration, impaction, thermal impaction and electrostatic precipitation are explained together with the methods of counting samples to determine free silica. Konimetric and gravimetric techniques for dust sampling are compared and contrasted. [Radiation Measurements] Both collective and personal dosimetry systems are used in the Canadian uranium mining industry and lectures are presented on each. Techniques and possible sources of error are discussed for a variety of radon and radon daughter measurement methods - Lucas method, Tsivoglou and modified Tsivoglou, Kusnetz, Rolle. Instant working level meters and personal alpha dosimeters are explained in terms of calibration, maintenance, readout and estimation of accuracy. A lecture outlining dose estimation by means of bio-assay, whole-body counting and the use of TLD's concludes the topic. Record-Keeping An overview of the problems of changing limits,

Jan 1, 1981

By R. F. Abernethy

A small-scale method was developed for determining the free-swelling index of coal samples of limited quantity, especially the macerals. Results of a series of tests using a 0.3-gram sample correlated well with those by the standard method using a 1-gram sample. The standard and small-scale methods are modified to give unrestricted swelling for those coals having swelling index numbers above 7.

Jan 1, 1971

By J. Derwin King, Harrison R. Cooper

Applications of nuclear magnetic resonance (NMR) offer possibilities for on-line sensing of the concentrations of several elements in flowing sample streams. In addition to hydrogen, these elements, generally of low-order atomic number, include aluminum, phosphorus, fluorine, sodium, boron, and lithium contained in minerals having commercial importance. Many such elements have been difficult or impossible to successfully measure on-line using the more familiar X-ray fluorescence and neutron activation analysis techniques. The availability of practical on-stream analysis methods is essential to applying advanced controls to processes incorporating these elements. On-stream NMR instrumentation has been demonstrated in the past for several process applications including, as an example, coal flow and analysis; and the technology has recently been extended to the measurement of phosphorous BPL in Florida beneficiation plants. The technique involves simultaneous sensing of proton (hydrogen) and 31P intensities to provide data for continuous calculation of BPL in the phosphate through calibration to volume fractions of water and solids. Initial operating results are described using the PhospholyzerTM on-stream phosphorous analyzer designed for plant application.

Jan 1, 1990

By Borsaru M, Wylie AW

A neutron irradiation technique has been developed which is suitable for the determinat- ion of the iron and aluminium content of iron ore fines (-6 mm particle size) on a moving rubber conveyor belt. The determination of iron entails measure- ment with a NaI(Tl) gamma ray detector of the characteristic prompt gamma rays (7.64 MeV) due to thermal neutron capture in iron, while the determination of aluminium is based on thermal neutron activation analysis. For the latter a second detector must be placed down- stream to monitor the 1.78 MeV gamma radiation emitted after activation of aluminium. Although conveyor speed has no effect on the Fe measurement, it has an adverse influence on the aluminium signal, and the belt speed should not exceed 0.1 m/s if good accuracy is required. Static trials on a 460 mm rubber conveyor belt with constant ore geometry indicate that for iron an accuracy of ¦ 1.2% Fe (2a) can be achieved for crushed run-of-mine ore at

Jan 1, 1978

By Mitchell G, Clarke C

The high oas emissions which are associated with high production lonowall mining have provided a need to investigate the limitations and reouirements of the various gas control methods. The major relationships between oassiness and various other parameters are presented with computer analysis being adopted to assess the respective correlations. Some of the relationships are studied in detail with emphasis being placed on methods for overcomino the changes in conditions resulting from high production levels. The importance of the various drainage systems which can be adopted to combat high gassiness levels are analysed. Logical and necessary steps are also proposed for gassiness prediction and data monitoring as well as various combinations of gas drainage systems. The gassiness prediction methods which are discussed outline the need for a sound knowledge of the established worldwide methods together with a comprehensive study of the local mining and geological environment in order to develop a system which is adaptable to the changing conditions. This is particularly important in mines where high coal production levels are anticipated and the need for accurate gassiness relationships is essential.

Jan 1, 1988

By M. Modis

According to previously established theoretical analysis and under certain conditions, a critical sampling grid can be determined for an earth-related space-distributed natural variable. Sampling above this critical limit adds little to the mapping results, while based on this limit the ideal process of reproducing the original phenomenon is theoretically defined. The objective of this paper is the application of the above theory to the Klidi lignite deposit in Florina, Greece, where Public Power Corporation (Greece) has conducted a sampling campaign to estimate the deposit thickness and its heating value. Data acquired for these two variables were analysed in the space domain in order to derive their respective correlation functions. The structural analysis of the deposit generated two covariance models, one for the thickness and one for the heating value, from which the critical sampling grid was identified. The conclusion drawn is that in some parts of the deposit the sampling grid is denser than required. Finally, an optimal sampling grid is proposed in order to gain the maximum information at the lowest cost.

Jan 1, 2006

By James Giulianelli

Personnel at the Jet Propulsion Laboratory (JPL) are studying the technology and applications of salt-gradient solar ponds (see below) for both electrical and thermal energy generation. The brine extraction and processing site operated by the Kerr-McGee Corporation at Searles Lake, California, offers ideal conditions for economic construction of solar ponds. Furthermore, since rising conventional energy costs adversely affect the economic recovery of brine by the present process, this site was selected for a study on the feasibility of integrating the solution mining of trona (Na2CO3?NaHCO3?2H20) in the lower salt with solar ponds for heating. The major emphasis of this study was to determine whether inexpensive thermal energy available at the brine extraction site would be useful in extracting increased mineral value from the resource. The present operation, which involves the simple extraction of the complex brine and its processing at the adjacent plant, is sometimes referred to as solution mining. Since the concept discussed in this paper involves injecting a heated sodium sulfate brine to dissolve carbonate underground, the proposed scheme is referred to as "enhanced" solution mining. The subject is discussed in greater detail in a recent JPL report. (1)

Jan 1, 1981

By Michael S. Wieland

The work-principle method was developed for theoretically resolving toxic fumes from non-ideal charge formulations. The whole description of a wanted process refers to macroscopic changes resulting from removing and imposing constraints that work one at a time to chronologically render trajectory terminal (key) states. The trajectory resolution utilizes a thermodynamic quasi-potential or negative work function, and numeric results require some appropriate standard thermodynamic (equilibrium) reaction code TDRC. The underlying method is unable to restrict reactions, tailor the work output or resolve states within the trajectory transitions, so the trajectory terminology is used somewhat figuratively. The work-principle model has the working fluid (reaction material) interacting with a tremendous reservoir (chamber air and walls), while forecasting the work performed upon a mechanical agent. Within the underground test chamber, the widening fume zone undergoes a decline in temperature, a reduction in reaction rates, resulting in out-of- equilibrium circumstances at the Q*-point, representing the measurement state. Rather than coping with the hard issues of non-equilibrium, the toxic fumes are resolved numerically for the Z-point, rendered by a zero-net- interaction energy constraint. Though other techniques require complex equation-of-state EOS for the whole trajectory, the work-principle formulation eludes the issue, requiring an EOS that works just for the terminal-state. Under the circumstances, the Z-state is reconcilable with the ideal-gas domain, and relevant TDRC results yield the restricted state in a numerical way for different charge formulations. The work principle makes it hard to remedy or to tamper with the resulting Z-point fumes: non-macroscopic trajectory readjustment is forsaken, terminal states are results rather than stipulations, and resetting the EOS formula constants would be ineffectual. Though the non-equilibrium portion remains unresolved, it is noteworthy that the work principle rigidly fixes the Z-state, thereby reducing the uncertainty for rendering reaction-rate models characterizing the non-equilibrium Z-Q* transition. Though more refinements are needed, some Z-point fume results are included to illustrate the threshold (minimum) resolving capacity of the work- principle formulation.