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By C. Carlson, W. Muir

"The oxygen demand of the complex lead-zinc-iron feed at the Cyuro Anvil concentrator was determined denendent on the cyanide ion con-contration of the pulp. By redistribution of the cyanide [ ] the grinding circuit in direct proportion to the amount of surface area created, a more activated flotation feed in obtained.Monitoring the oxygen demand of the flotation feed and grinding mill discharge has proved useful in diagnosing metallurgical problems day to day operation."

Jan 1, 1976

By Qingming Feng, Jinhong Zhang

A study has been carried out to apply fly ash as a high strength, water-resistant precast construction material through geopolymerization. Experiment results show that the working conditions such as water content, the concentration of NaOH, curing temperature, and curing time significantly affect the mechanical property of geopolymermatrix. Through optimization, an above-100MPa compressive strength has been achieved with the geopolymerization products. The optimum working conditions involves 10MNaOH concentration, 14–15% water content, and curing at 90 °C in an oven for 1 day or at ambient condition for 3 weeks. Adding Ca(OH)2 does not help to increase the compressive strength of the specimen.Water soaking tests show that the geopolymerization product has a very high water resistance without losing noticeable compressive strength, even after a 1-month soaking time. To elucidate the geopolymerization mechanism, microscopic techniques such as SEM/EDS (scanning electron microscopy and energy-dispersive X-ray spectroscopy), XRD (X-ray diffraction) and ATR-FTIR (attenuated total reflectance Fourier transform infrared) are also applied to investigate the microstructure, the elemental and phase composition of geopolymerization products. The findings of the present work provide a novel method for applying fly ash as a high-strength water-resistant precast construction material.

Aug 17, 2020

During development mining, ventilation capacity may decrease and the ventilation requirements may depart from initially planned values depending on the mining rate, increases in the methane emission rate, and changes in ventilation airway leakages. Insufficient ventilation air quantities and the occurrences of high methane liberation rates can overwhelm the existing quantity of ventilation air and result in elevated levels of methane gas during development mining. This condition can both limit the development of that section and increase the risk for an ignition that may lead to an explosion. Thus, the prediction of ventilation air requirements prior to mining can enhance worker safety by reducing the likelihood that explosive methane-air mixtures form. This study presents an approach for prediction of methane inflow rates using coalbed methane reservoir modeling. For this purpose, a two-phase coalbed reservoir model of a three-entry type roadway is developed. In the model, grids are dynamically controlled to simulate development of entries. Examples are given for methane inflow and ventilation air requirements as a function of mining rate, development section length, mining height, and the existence of degasification boreholes. This technology can be used to limit the methane concentrations occurring as a result of the influences of various coalbed and operational parameters.

Jan 1, 2008

By Stacy Loizeaux

The Beirut Hilton Hotel, which was built in 1975, but never occupied, was imploded on Sunday, July 14, 2002 by Controlled Demolition, Inc. (CDI) of Phoenix, Maryland and their client, Optimal Engineering Consulting & Contracting, SARL, (OECC) of Antelias, Lebanon to make room for a new hotel. Twenty-seven years ago, just days before the grand opening, the Hilton Hotel became the site of fighting in Lebanon’s Civil War. Christian and Muslim militiamen fought room to room for control of the building and other nearby hotels. The Hilton, two other major hotels and other high-rise buildings were ravaged by the fighting. The building was one of the three major hotels badly damaged, but not rebuilt, in Lebanon. Located in the City Center, the Hilton stood out in a major redevelopment area which, in recent years, had erased the scars of the 15 year long Civil Wa r.

Jan 1, 2003

By Jan E. Nesset, Phillip J. Mackey, Joo Y. Kim, Giovanni Di Prisco, André R. Laplante

Understanding the appropriate gold recovery to associate with copper recovery when assessing laboratory testing on porphyry deposits is often complicated by several factors including variable and/or complex mineralogy, and the variability contributed by the low Au content of the various flotation products. As a result, gold recovery is often underestimated and the value contributed by the gold to project economics is less than it should be, a problem that could influence overall project viability. Typically, for these types of deposits, the gold recovery is found to be lower than the copper recovery. In this unique project, having the objective of seeking a better understanding of gold recovery relative to copper recovery, mill feed samples from a selection of six operating world-class Cu-Au low-grade deposits were collected along with the mill metallurgical results for the corresponding sample periods. The samples were subjected to laboratory flotation tests, as well as the Laplante gravity recoverable gold (GRG) test, mineralogical assessment and cyanidation leaching. The aim was to better understand the copper and gold recovery relationship, the links between laboratory and plant flotation performance, the influence of mineralogical differences, and the potential for enhancing gold recovery by gravity recovery techniques. A new correlation of copper and gold recoveries based on the results is presented in the paper. The results showed that the link between copper and gold recoveries established in the best laboratory tests were maintained in the plant results, and further, that the potential for improving Au recovery by gravity or flash flotation methods is directly proportional to the amount of gold greater than 75 microns.

Jan 1, 2005

The Fosterville Goldmine in Victoria employs bacterial oxidation (BIOX« Process) to liberate gold from its flotation concentrate. Gold occurrence is primarily as submicron particles in pyrite and arsenopyrite and has been described as being in æsolid solutionÆ and therefore not amenable to direct cyanidation even with fine grinding. Once liberated by the oxidation process, the gold is then available for cyanide leaching. While the oxidation process is very effective, it has been found that a portion of the liberated gold can become suspended in the liquid phase in what appears to be a colloidal state. This liquid becomes a waste stream during washing of the oxidised solids and the suspended gold is therefore lost. This paper discusses investigations into the causes of the loss and also describes the successful use of quebracho tannin in reducing colloidal gold loss. Laboratory and subsequent plant trials, showed a gain of 2.6 per cent in overall gold recovery based on mill feed and waste stream data.

Jan 1, 2009

By Richard P. Graff

Author?s note: Diversity in practice exists in the application of Generally Accepted Accounting Principles (GAAP) for purchase price allocations with respect to the recognition of Value Beyond Proven and Probable Reserves or VBPP, as defined by the Emerging Issues Task Force (EITF) in EITF 04-3: ?Mining Assets: Impairment and Business Combinations?. This diversity appears to arise from differing interpretations of what constitutes sufficient information to value components of VBPP in business combinations. Concerned with this diversity in practice, respected members of the mining community formed a working group which prepared an issues paper that discussed this diversity and provided recommendations for recognition and valuation of VBPP in business combinations. The working group then submitted this paper to the EITF, requesting further guidance be issued on the concept of VBPP. In conjunction with the submission to the EITF, the working group also provided this paper to the United States Securities and Exchange Commission (SEC) for review and comment. The EITF discussed this issue at its May, 2008 agenda committee meeting. However, it declined to add this topic to the EITF agenda for further consideration. Absent additional guidance on VBPP from the EITF, the working group submitted a proposed definition of VBPP to the U.S. Securities and Exchange Commission for its consideration. The following article, which is consistent with the issues paper that was submitted to the EITF and the SEC, discusses the components of and valuation techniques for VBPP. The correspondence with the U.S. Securities and Exchange Commission, which includes the proposed definition of VBPP by the working group, is attached as Appendix 1 to this article.

Jan 1, 2008

By T. Saito, S. Murata

An original concept of JRC-diagram that can evaluate JRC and its size-effect by using a fractal model was proposed. In order to confirm the applicability of the JRC-diagram, first, JRC of the tensile fracture surfaces of a granite and a sandstone were evaluated by both the JRC-diagram and Barton's JRC-profiles, and then, it was compared with the JRC inversely calculated from the peak shear strength that is obtained from the shear test for each fracture using Barton's empirical equation. As a result, JRC evaluated by the JRC-profiles was much smaller than the inversely calculated JRC. On the other hand, it became clear that JRC evaluated by the JRC-diagram is almost the same with the inversely calculated JRC, if the size of interlocking is evaluated correctly. Therefore, for the JRC evaluation, it is thought that the JRC-diagram is more applicable than the JRC-profiles. Als ein neues Verfahren zur Bewertung des Rauheitsindexes JRC für die Bruchfläche von Felsenschichten anhand eines fraktalen Modells, wobei auch der Maßeffekt berücksichtigt wird, wird ein JRC-Diagramm vorgeschlagen. Um die Angemessenheit der Bewertung vom JRC mit diesem JRC-Diagramm festzustellen, wurden die JRC-Werte an einer Bruchfläche zwischen Granit und Sandstein sowohl mit dem JRC-Diagramm als auch mit dem herkömmlichen JRC-Profilverfahren bewertet. Anschließend wurden die durch die beiden Verfahren ermittelten Werten mit den JRC-Werten verglichen, die von den Schertestergebnissen mit Hilfe von Bartonschen Erfahrungsformel zurückgerechnet werden können. Daraus ergab sich, daß das JRC-Profilverfahren ziemlich kleinere JRC-Werte gibt als bei der Zurückrechnung, während die JRC-Werte durch das JRC-Diagramm unter entsprechender Bewertung des Ineinandergreifungsmaßes an der Bruchfläche beinahe gleich sind wie die zurückgerechneten Werte. Diese Tatsache weist darauf hin, daß das JRC-Diagramm eine bessere JRC-Bewertungsmethode als das JRC-Profilverfahren darstellt. Nous avons proposé le diagramme JRC, nouvelle méthode d'évaluer JRC qui est un indice de rugosité superficielle d'une fracture de roche à l'aide du modèle de fracturation, compte tenu de son effet d'échelle. Pour vérifier la validité de JRC évalué au moyen de ce diagramme, nous avons évalué JRC d'une fracture de roche, granite et grès, par le diagramme JRC et le profil JRC, méthode conventionnelle, et les résultats ainsi obtenus ont été comparés avec la valeur de JRC calculée en sens inverse à l'aide de la formule empirique Barton sur la base des résultats de l'essai de cisaillement des fractures. Il en résulte que la valeur de JRC obtenue par le profil JRC était assez faible en comparaison avec la valeur calculée en sens inverse alors que celle de JRC obtenue par le diagramme JRC correspondait approximativement à la valeur calculée en sens inverse à condition d'évaluer l'échelle d'endentement d'une fracture. Par conséquent, nous considérons que le diagramme JRC est une meilleure méthode d'évaluation de JRC par rapport au profil JRC.

Jan 1, 2003

By Thomas J. Weaver

Piles extending through soft soil near the ground surface will have a relatively low lateral stiffness. As a result, lateral serviceability limits may control the number of piles required for foundation support. Improving near surface soil properties may significantly increase lateral pile stiffness and thus reduce the number of piles required for the foundation. A series of analyses have been performed to assess the depth and lateral extent of soil improvement required to significantly increase lateral foundation stiffness. Analyses consisted of Winkler type beam on a spring foundation and three-dimensional, linear elastic finite element analyses. Results from the analyses show that lateral pile foundation stiffness can be doubled when soil properties are improved to a depth and lateral extent of 5 pile diameters. In order to achieve this increase in foundation stiffness, the modified/improved soil modulus of elasticity needed to be approximately 5 times greater than adjacent unimproved soil. This magnitude of soil improvement over such a limited lateral extent suggests that limited soil improvement can result in more economical foundation designs at soft soil sites.

Jan 1, 2006

By W. P. Nel

The introduction of the Higher Education Qualifications Framework (HEQF) and the updated Higher Education Qualifications Sub-Framework (HEQSF) has caused many South African university departments to rethink their programme qualification mixes (PQMs). In addition to the requirements stated in the HEQSF, a number of other factors have to be taken into consideration by a university department. These factors include, for example, the standards generated by the Engineering Standards Generating Body (ESGB) and subsequently approved by the Engineering Council of SA (ECSA) and the need to prepare students for various categories of professional registration with ECSA. This means that a university department has to choose the correct mix of Learning Programmes (LPs) from the HEQSF menu (which consists of 13 types of LPs). Preparing students for ECSA registration is aligned with the mission of universities, which is to teach and undertake research. However, research and the LPs associated with research go beyond the requirements for current ECSA registration. Assuming that universities offering engineering LPs would elect to prepare students for both ECSA registration and teach them to produce research outputs, which is mostly done at Master and Doctorate levels (NQF Levels 9 and 10), then it follows that academics are more interested in NQF Level 5 to 10 pathways (abbreviated as ?L5-10?) rather than the shorter pathways required towards professional registration. (For example, ECSA requires an NQF L5-L7 pathway for registration as a candidate professional technologist. This specific pathway may consist, for example, of two LPs, namely the 360-credit Diploma and the Advanced Diploma.) A L5-L10 pathway is a combination of LPs that will prepare the learner with a NSC (or equivalent qualification at level 4) to Doctoral level (level 10). Universities may choose at least four major pathways from the HEQSF menu in order to educate and develop students from NQF Level 5 to 10. However, various pathways towards registration in the category of candidate with ECSA are also embedded into these four NQF L5-L10 pathways, where each consist of a unique combination of LPs. Each of these pathways has an opportunity cost, and economic reality means that smaller departments may have to choose between the four pathways. Of all the many factors involved in PQM decision-making, the focus of this paper is on the HEQSF requirements, ECSA standards, and ECSA registration and how these, together with the various qualifications and educational LPs provided for by the HEQSF may impact on the PQM decision taken by engineering departments and schools at South African universities. The proposed four NQF L5-L10 ?pathway tool? for PQM decision-making may be useful for pointing out the advantages, disadvantages, and applications of the various pathways and combinations of pathways. Rather than deciding from a menu of thirteen qualifications and associated LPs, this article proposes that decision-making be undertaken on the basis of a menu of four main articulated ?NQF L5-L10? pathways (which also include one or more of the ECSA?s pathways for professional registration). The proposed ?NQF L5-L10 pathway? tool is an attempt to move one step closer to the aim of achieving a structured decision-making approach for designing a PQM at departmental level.

Jan 1, 2014

By H. P. Jacobi

"INTRODUCTIONPine Point Mines, operated by Cominco Ltd., is located approximately 65 miles east of Hay River, N.W.T. on the south shore of Great Slave Lake.The milling operation started in the fall of 1965 with a capacity of 5,000 tpd. An addition was put into operation late in 1968 to bring the nominal capacity up to 8,000 tpd. The present milling rate is 11,000 tpd.With a feed grade of approximately 2.9% Pb and 6.0% Zn the annual concentrate production amounts to roughly 130,000 SDT of lead concentrate and 370,000 SDT of zinc concentrate for a total of 1/2 million tons of product.This tonnage is moved by railroad. Pine Point is served by the Great Slave Lake Division (G.S.L.) of the Canadian National Railways which connects to the Northern Alberta Railway System (N.A.R.) at Roma Junction, at Peace River, Alberta. The system in turn connects to the CNR and the CPR in Edmonton, Alberta. From here the concentrates move inland chiefly to Trail, B.C., with some shipment to other Canadian and U.S. smelters, and to the port facilities of Pacific Coast Terminals at New Westminster, B.C. for offshore export.This paper will focus on the problems associated with the movement of lead and zinc concentrates from Pine Point to port facilities on the west coast."

Jan 1, 1975

By J. S. Harington

Our purpose is to record and to explain the widely changing numbers of the huge total of black workers on the gold mines of South Africa over the century from 1896 to 1996. These men were recruited from up to twenty territories, and their contributions are examined. The major areas providing labour over this long period have been Lesotho, the former Transkei within South Africa and Mozambique. From 1989 to 1996, for instance, these three areas accounted for over sixty per cent of the total labour force (tlf). Our principal Figure 1 shows the tlf fluctuating through time to reach a peak of 480 000 in 1988. Irregular falls are also documented with the most serious in 1995 to 180 000. Based on this graph we consider the political, economic, sociological and historical reasons behind these changing employment opportunities. These have included external world-scale events such as war or depression, as well as internal changes of national economy and policy. We show the importance for numbers employed of the discovery of gold in the Orange Free State in 1946, the influence generally of the ?Winds of Change? and the firm maintenance by the State of law and order. Varying gold production costs and profitability against high tax rates, allied with increasing wages and a lack of development capital, have led in the last decade to employment falling by fifty per cent, despite an actually higher value of gold output. Finally, this analysis considers the role of the migrant labour system as it affects, and is affected by, conditions in the gold mining industry, with special reference to its less than humane consequences in the numerically dominant territories of Lesotho and Transkei.

Jan 1, 2004

This report, 27th in a continuing series1, describes Bureau of Mines research and technologic work on coal and related investigations during 1962. While the brief discussion in each section of the report presents only the highlights of Bureau work during the year, details of many investigations can be found in publications cited in this text. Other work, reported here for the first time, will be covered in greater detail in later publications. Recent trends in coal research and technology both at home and abroad were reviewed in several publications2. Bureau research, as in the past3, continued to stress improved methods of mining, preparing, processing, and using coal. The program included a wide variety of applied and basic studies for developing information useful to the coal mining industry and the coal consumer while promoting wise conservation and utilization of our coal resources.

Jan 1, 1963

By G Hayes

Ore from the Browns deposit near Batchelor, in the Northern Territory of Australia, is a fine-grained polymetallic sulfide ore hosted in graphitic black shale. Minerals of economic significance are seigenite (Co,Ni)4S3, Galena (PbS) and Chalcopyrite (CuFeS2) with minor Sphalerite (ZnS). Gangue minerals include quartz, carbon and K-feldspar. The grain size is fine, with a significant amount of the seigenite present as Early flotation work determined that a grind size of around 20 microns was required to achieve clean sulfide concentrates. This work recommended oil agglomeration flotation, in which small sulfide minerals were collected, then loosely agglomerated with oil ahead of flotation into a heavily mineralised froth. In the 400 kg/hr prototype plant this froth proved unmanageable. A conventional flotation circuit after grinding to a P80 of 24 microns and using very low flotation pulp densities resulted in an 86 per cent cobalt recovery.The paper analyses further laboratory work which has increased cobalt recovery to 91 per cent by grinding to û250 microns ahead of flash flotation. The real cobalt recovery breakthrough comes from flash flotation of the whole mill discharge rather than the more usual flash flotation of cyclone underflow. Flash flotation tailings are ground to û38 microns and are floated under normal flotation conditions with only the scavenger concentrates being reground to 20 microns.A one tonne per hour prototyping campaign is scheduled to demonstrate the robustness of this circuit.

Jan 1, 2002

By C. J. Walker, J. S. Miller

This work was done in an attempt to find a simple solution to the problem of simultaneously changing terminal rate and terminal pressure under conditions of unsteady - state flow in porous media . Although the original aim was not realized , a method for encasing a sandstone core that would permit high - pressure ( 200 to 980 psi ) flow tests and the use of electronic equipment to measure pressures at points along the core during unsteady - state gas depletion was found to be feasible . The sandstone core used in this study was from the Bandera formation of Pennsylvanian age , Redfield , Kans . The core , cylindrical in shape with a 3.5 - inch diameter and 6- foot length , had a porosity of 15 percent and a permeability of 9 millidarcys .

Jan 1, 1963

The heap leaching of base metal ores can be applied within a number of different scenarios, each requiring its own set of parameters to be determined during the metallurgical testwork programme. The occurrence of acid-gangue reactions and its concomitant precipitation reactions is a factor common to all cases, and requires that the optimal irrigation acid strength be found that optimises the combination of extraction kinetics, acid consumption and possible premature blinding of the heap due to precipitation reactions. For the heap bioleaching of base metal sulphide ores the oxygen requirement needs to be determined for the design of the aeration system, and the operating conditions employed need to also facilitate bacterial growth over and above the acid strength optimisation mentioned above. For the heap bioleaching of chalcopyrite, the need to preserve heat in the heap becomes yet a further parameter of critical importance. For the heap leaching of uranium ore a choice is required between either chemical or bacterial oxidation, based on economic and processing factors. Frequently the operating parameters need to be determined for a circuit in which heap leaching is combined with tank leaching and/or pressure leaching. The processing implications and metallurgical testwork approach for each case is discussed.

Jan 1, 2007

By Robert Stefanko

This report abstracts project work performed for the USBM Grant No. GO-133077 during the period 19 June 1973 to 15 October 1974. Five reports have been separately produced and are as follows: 1. Mine Electrical Systems Evaluation - Cable Splicing, 2. Mine Electrical Systems Evaluation - Explosion-Proofing of Mine Containers, 3. Mine Electrical Systems Evaluation - Transient Analysis, 4. Mine Electrical Systems Evaluation - Mine Power System Performance, and 5. Mine Electrical Systems Evaluation - Model Coal Mine Electrical System Specifications. Abstracts of each comprise the balance of this executive summary, and 50 copies of each volume have been forwarded to the USBM under the terms of the grant agreement.

Jan 1, 1974

By William A. Gibson, Kenneth P. Neumann

In 1967, development of the Cyprus Thompson Creek molybdenum deposit began near Challis, ID. The first mining claims were staked on an intrusive rock out-crop. Exploration continued for 14 years. In 1978, the decision was made to develop the deposit. In Dec. 1980, approval was received for the environmental impact statement and facilities construction and waste rock removal began. By the middle of 1983, 126 Mt (139 million st) of rock had been removed and all facilities completed. Location The Thompson Creek project is located about 58 km (36 miles) southwest of Challis in Custer County, in south central Idaho. The mine and mill are situated between 2.2 and 2.6 km (7,217 and 8,530 ft) in elevation. The project is located in an isolated area. Surrounded by mountains, it is adjacent to the Sawtooth National Recreation Area. The Salmon river is 8 km (5 miles) south of the project. The project claim block is lo-

Jan 1, 1984

By Steve Kral

The upswing in prices for base and precious metals, industrial minerals and coal has allowed the global mining industry to ramp up production at existing mines and begin construction of proposed projects. In addition to satisfying shareholders, the industry is also providing good paying jobs and creating needed infra-structure in places that previously did not have either. However, the industry has learned that the prospect of jobs and infrastructure is not necessarily a guarantee that communities will allow mines to be built. The industry must maintain even higher environmental and reclamation standards. And mining companies must help communities plan for life after a mine is closed and the company moves out.

Jan 1, 2005

By M. R. J. Wyllie, Michael A. Torcaso

With the continued deep drilling of today, increasing numbers of high pressure and high temperature gas-condensate reservoirs are being discovered. Correspondingly, the ranges of properties of gas-condensate reservoir fluids are also being increased. The literature1*'." contains several excellent reviews of the property ranges in presently known condensate reservoirs. When one examines these property ranges, it becomes apparent that the need for reliable data is great if the engineer is to evaluate properly or appraise a gas-condensate reservoir. It is the purpose of this paper to present phase-behavior data that will point out some of the important variables that influence recovery from gas-condensate reservoirs produced by pressure depletion. All these variables may be resolved into two major categories: the hydroc:arbon composition of the reservoir fluid and the physical properties of the reservoir. But the variables which we will consider are those which are usually determined from well tests shortly after discovery and are, consequently, readily available to the engineer. They are as follows: (1) the producing separator gas-stock-tank liquid ratio, (2) stock-tank liquid gravity, and (3) reservoir temperature. Laboratory depletion studies have been performed on several reservoir fluids to illustrate the effect of changes in the cronsidered variables upon ultimate recoveries. The deviation factors, Z, of a series of reservoir fluids were determined experimentally to illustrate their order of magnitude and their effect upon the calculation of in-place reserves existing at high pressurcs and temperatures. The procedures followed in conjunction with the performance of these studies and their associated calculations are illustrated in Fig. 1. For the purpose of this paper, the depletion recoveries are expressed only in terms of pcr cent of initial stock-tank liquid, with the abandonment pressure assumed to be 500 psig. VARIATION OF RECOVERY WITH INITIAL PRODUCING SEPARATOR GAS-STOCK-TANK LIQUID RATIO The producing separator gas-stock-tank liquid ratio has long been one of the principal criteria in assumptions and generalized correlations' used for the estimation of ultimate recovery from gas-condensate reservoirs. Fig. 2 presents a plot of the cumulative recovery of stock-tank liquid at abandonment as a function of the initial producing separator gas-stock-tank liquid ratio. The graphical illustration represents the results of 44 laboratory depletion studies performed on actual gas-condensate fluids. These data are presented not only to illustrate the general trend of ultimate recovery increase with initial producing ratio increase but to emphasize the considerable variation in possible recovery at any given producing ratio. Table 1 presents the properties of two actual reservoir fluids chosen to illustrate the approximate extremities of producing ratios for gas-condensate systems. The fluids designated as A and B exhibited initial producing ratios of 3,400 and 114,000 scf/bbl, respectively. Fig. 3 presents a graphical comparison of the cumulative stock-tank liquid recoveries, calculated from the well-stream compositions and produced volumes for each fluid during depletion. It is to be noted that Fluid A exhibited a recovery of only 16.5 per cent when produced to an assumed abandonment pressure of 500 psig while the corresponding recovery for Fluid B was calculated to be 62.2 per cent. This difference in recovery, which exemplifies the general trend of recovery increase with initial producing ratio increase, is readily explained by consid-