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By J. C. Willett, J. R. Sanfilipo, P. D. Warwick

The U.S. Geological Survey has conducted an assessment of the Nation’s coal deposits that potentially could be mined during the next 30 or more years. For the Gulf Coastal Plain region, the assessment includes reviews of the stratigraphy, coal quality and resources, and coalbed methane potential of the Cretaceous, Paleocene, and Eocene coal deposits in the region. The results of these efforts are a series of digital maps, text, and tables published in CD-ROM format. Although abundant coal resources are available in the Gulf Coast region, coal quality issues may limit large-scale development in the future. Additional data are required to better evaluate the coalbed methane resource potential for the Gulf Coast region.

Jan 1, 2001

By J. R. Piper

“Old Borate,” located in the Calico Mountains east of Barstow, California, lead domestic colemanite production from 1884 through 1907. Mineral exploration at “Old Borate” in the early 1980's, examined borate mineralization in Tertiary lacustrine strata. Surface sample and drill hole locations, geology and structure, were hand-drafted on paper maps. To re-evaluate this data, the information was digitized using Geographic Information Systems software. Digital Elevation Model based terrain modeling integrated surficial samples with drill hole data to locate favorable drilling targets. Structural relationships were used to identify hypothetical resources formed by the leaching of boron from surface exposures, redeposited at depth.

Jan 1, 2001

By Beevers J

The Ok Tedi Project is now a high production open-pit porphyry copper mine located in the Star Mountains of Papua New Guinea (PNG). At present, total daily production is 190 000t of ore and waste. Large scale drilling and blasting has only been in operation since 1988, prior to which all material was removed by ripping and dozing. This paper reviews the steps taken over the last 12 months in establishing a more efficient drilling and blasting operation and highlights the significant reduction in powder factor. These improvements have been achieved largely through the introduction of air-bags, controlled pattern expansion and an overall focusing on the operation by involving consultants, ICI's technical service and internal departments.

Jan 1, 1991

The results of self potential geophysical surveys conducted over base metal prospects near Orange, Goulburn, and Wellington, N.S.W., indicate that this rapid and inexpensive exploration procedure merits wider application within eastern New South Wales, and in similar environments elsewhere.

Jan 1, 1973

The paper deals with the importance of design, and of codes of practice, in ensuring safe working conditions in mines. The design principles involved in the design process are dealt with, and the importance of a logical design process is emphasized. The links between the requirements for developing a code of practice, embodied in the existing guidelines for the preparation of such a code, and the design principles and process are considered in some detail. Finally, suggestions are included which may provide improvements to the code and hence, ultimately, lead to further improvement in safe working conditions.

Jan 1, 2003

By R Salmon, C Jones

This paper examines the recent trend towards sustainability reporting and the application of the Global Reporting Initiative (GRI) æSustainability Reporting GuidelinesÆ. It also reviews reporting in the context of the Australian Minerals Industry Code for Environmental Management, as well as the status of public sustainability reporting globally in the minerals industry. The public reporting of environmental, health and safety, social/community and economic performance has evolved over the past two decades. Initially, separate and to some degree disparate documents were produced to report performance in each distinct area. In the early to mid 1980Æs some organisations had begun to report their environmental performance through some minor commentary in their annual financial reports or through ætokenisticÆ leaflets, often used as public relations exercises. Due to more media coverage and an elevated level of public scrutiny, organisations are no longer merely reporting their good performance, but also their bad and indifferent performance. In recent years these once separate environment, health and safety and community public reports have further evolved to become more integrated, reflecting organisations embarking on the reporting of their progress towards sustainable development. The primary factor in driving the evolution of sustainability reporting has been the increasing influence of stakeholders. Two groups of external stakeholders that have had a significant influence over public sustainability reporting in recent years have been non government organisations (NGOs) and socially responsible investment funds. Significant expenditure is involved in the preparation and publication of a sustainability report however many organisations do not appear to have examined in detail what they are really trying to achieve from their public reporting process. It is important to establish objectives for the public reporting process to achieve maximum benefits. Without a framework of public reporting objectives, the benefits of the reporting process to the organisation will not be recognised and the considerable expenditure involved will be increasingly difficult to justify. We believe that by focussing on the process rather than the document, significant benefits to the organisation can be gained. Indeed, with a proper framework of objectives and targets, the reporting process can be used as a vehicle to drive organisational change, implement management systems and improve performance. An idealised framework for a public sustainability reporting process sees the organisationÆs sustainability policies drive the entire process and determine the sustainability objectives. Specific targets are then set to realise those objectives. The targets will govern performance indicators that should be used to measure the success of target achievement and which will also define what data need to be collected. Evaluation is a key component of the reporting process to measure the success of target achievement and progress in realising objectives, as well as review the need for new targets to be set. The actual production of a public document is only one, albeit important, component of the overall reporting process. The challenges that lie ahead for sustainability reporting primarily relate to the integration of environmental, social and economic performance reporting as organisations integrate their approach to these areas. This will only happen as the culture of an organisation changes to not only accept the principles of sustainable development but to implement those principles in daily operations. The reporting process has the potential to drive that cultural change by communicating the organisationÆs sustainability objectives and setting challenging targets for their realisation. Public sustainability reporting will only achieve its maximum value when it forms an integral part of an organisationÆs sustainability management system and culture.

Jan 1, 2002

By N. Mulaudzi, S. Archer

"Direct cobalt electrowinning was developed to produce unrefined cobalt metal as an alternative to producing a mixed hydroxide product (MHP), which is the common cobalt intermediate product in African Copperbelt operations. MHP is preferred due to the high cost of producing high-grade cobalt cathode. Direct cobalt electrowinning test work results have shown that the purity of the unrefined cobalt metal produced from a low-grade copper solvent-extraction raffinate stream was ~97% (w/w), which is significantly higher than the MHP purity (up to 45% (w/w) Co). The current study investigates whether direct cobalt electrowinning would increase the profitability of African Copperbelt copper–cobalt oxide operations, when compared with the MHP flowsheet. An order-of-magnitude economic evaluation was conducted using dynamic differential discounted cash flow models on a “bare-bones” basis, using a 10% discount rate. Three variables were evaluated, namely; reagent utilisation extents, precipitation extents and filter-press wash efficiency. Multivariable risk analysis was also conducted using the Monte Carlo simulation technique to understand the impact of key project drivers. The financial study results indicated that a direct cobalt electrowinning flowsheet could potentially result in a higher mean net present value (NPV) compared with the MHP flowsheet. Cobalt recovery was found to have the most significant impact on the NPV. In addition to increased profitability of African Copperbelt operations, direct cobalt electrowinning has the potential to reduce the environmental footprint of operations as well as addressing the Democratic Republic of Congo government’s drive towards export of higher value metal products instead of low-grade intermediates."

Jan 1, 2015

By S. Panigrahi

The SO2-ammoniacal ammonium sulfate leach liquor generated by leaching of manganese nodules, after removal of minor quantities of iron and manganese, contained copper, nickel, cobalt, zinc and (NH4)2SO4. After extraction of copper from the leach liquor with LIX 84I, stripping of ammonia from the Cu-barren raffinate was carried out followed by precipitation of metal ions from the ammonia-stripped solution as sulfides. Leaching of the sulfide precipitate was carried out with H2SO4 to obtain a leach liquor containing 0.58 kg/m3 Cu, 2.67 kg/m3 Zn, 2.00 kg/m3 Co, 24.68 kg/m3 Ni and 10.0 kg/m3 (NH4)2SO4. After extraction of copper and zinc from the sulfate leach liquor with LIX 84I and D2EHPA, respectively, the solution was left with Co and Ni. Extraction of cobalt from the Cu- and Zn-free solution was carried out with 0.1 M PC88A and stripping of the cobalt-loaded organic was carried out with the cobalt-spent electrolyte (pH 1.4). Extraction of nickel from the cobalt-free solution was carried out with 90% neutral 1M NaPC88A followed by stripping of the nickel-loaded organic with 120 kg/m3 H2SO4 solution. Extraction of metal ions increased with increasing equilibrium pH and extractant concentration. The maximum separation factors, with respect to the pH and extractant concentration variation studies, were 3796.7 and 15350.0, respectively. The extracted species for the metal ions were CoA2?3HA and NiA2?5HA.

Jan 1, 2009

By Y. Sasseville

"Niobec has been using vibrating screens and screw classifiers as a double stage classification in its grinding circuit since the very beginning of its operation in St-Honoré. Most of the other mineral processing plants around the world uses cyclones as the classification device in their grinding circuit. The difference between these two methods are well known in terms of capital cost and grinding efficiency but the differences in terms of the impact on the downstream processing stages are a lot harder to predict and are case specific. In the interest of lowering the capital cost of a future expansion project, Niobec decided to test the cyclones in its actual grinding circuit and evaluate their impact on the recovery of the downstream processing stages as well as the operating cost of the mill. We switched between cyclones and screens for 8 month in 2013 and early 2014 and we are now operating only with cyclones since march 2014.INTRODUCTIONThe Niobec mine and concentrator were built in the mid 70’s and at that time, the mill was processing 1 500 tons per day. Over the years, many expansion projects have brought the plant to 7 000 tons per day. Throughout the initial concentrator design and commissioning, screens have been chosen over cyclones because of their higher classification efficiency which is known to reduce variability and limit the fine generation especially due to a high undersize classification efficiency. Just like many other plants, fine particle generation is a major problem at Niobec because of its negative effect on downstream processing stages. In the interest of lowering the capital cost of a future expansion project, Niobec’s engineering team decided, 35 years later, to test the cyclones in its actual grinding circuit and evaluate their actual impact on the final recovery and the operating cost of the mill.The grinding circuit is separated in two lines which will be called Circuit #1 and Circuit #2 along this paper. Circuit #1 is, as you can see in Figure 1, composed of a rod mill and two parallel ball mills in closed circuit with screens and screw classifiers. The screens oversize are sent to the screw classifiers while the undersize are sent to the next processing stage. The screw classifiers overflow are both sent back to the pump box while their oversize streams return in their corresponding ball mills for further grinding. Circuit #2 is, as you can see in Figure 1, quite the same as Circuit #1 except it has only one set of screw classifier and ball mill. Figure 1 also shows the modification in arrangement each circuits went through to integrate the new cyclones. One of the ball mills in Circuit #1 now appears dotted because it can still be used but is not now"

Jan 1, 2015

By L. J. Health

Synthetic rock with predictable porosity and permeability has been Prepared from mixtures of sand, cement and water. Three series of mixes were investigated primarily for the relation between porosity and permeability for certain grain sizes and proportions. Synthetic rock prepared of 65 per cent large grains, 27 per cent small grains and 8 per cent Portland cement, gave measurable results ranging in porosity from 22.5 to 40 per cent and in permeability from 0.1 darcies to 6 darcies. This variation in porosity and permeability was caused by varying the amount of blending water. Drainage-cycle relative permeability characteristics of the synthetic rock were similar to those of natural reservoir rock. INTRODUCTION The fundamental behavior characteristics of fluids flowing through porous media have been described in the literature. Practical application of these flow characteristics to field conditions is too complicated except where assumptions are overly simplified. The use of dimensionally scaled models to simulate oil reservoirs has been described in the literature. 1-3 These and other papers have presented the theoretical and experimental justification for model design. Others have presented elements of model construction and their operation. In most investigations the porous media have consisted of either u ncon soli da ted sand, glass beads, broken glass or plastic-impregnated granular substances—materials in which the flow behavior is not identical to that in natural reservoir rock. The relative permeability curves for unconsoli-dated sands differ from those for consolidated sandstone. The effect of saturation history on relative permeability measurements is discussed by Geffen, et a1.4 Wyga15 has shown quite conclusively that a process of artificial cementation can be used to render un consolidated packs into synthetic sandstones having properties similar to those of natural rock. Many theoretical and experimental studies have been made in attempts to determine the structure and properties of unconsolidated sand, the most notable being by Naar and Wygal.6 Others have theorized and experimented with the fundamental characteristics of reservoir rocks. This study was conducted to determine if some general relationship could be established between the size of sand grains and the porosity and permeability in consolidated binary packs. This paper presents the results obtained by changing some of the factors which affect the porosity and permeability of synthetically prepared sandstone. In addition, drainage relative permeability curves are presented. EXPERIMENTAL PROCEDURE Mixtures of Portland cement with water and aggregate generally are designed to have certain characteristics, but essentially all are planned to be impervious to water or other liquids. Synthetic sandstone simulating oil reservoir rock, however, must be designed to have a given permeability (sometimes several darcies), a porosity which is primarily the effective porosity but quantitatively similar to natural rock, and other characteristics comparable to reservoir rock, such as wettability, pore geometry, tortuosity, etc. Unconsolidated ternary mixtures of spheres gave both a theoretically computed and an experimentally observed minimum porosity of about 25 per cent.7 By using a particle-distribution system, one-size particle packs had reproducible porosities in the reproducible range of 35 to 37 per cent.6 For model reservoir studies of the prototype system, a synthetic rock having a porosity of 25 per cent or less and a permeability of 2 darcies was required. The rock had to be uniform and competent enough to handle. Synthetic sandstone cores were prepared utilizing the technique developed by Wygal.5 Some slight variations in the procedure were incorporated. The sand was sieved through U. S. Standard sieves. A 18-20 sand denotes that the sand passed the Number

Jan 1, 1966

By David C. Grant

A laboratory technique for simulating in-situ uranium mining was developed and used to determine the effects of leaching variables on permeability, uranium recovery, leach solution interaction with the ore-aquifer environment, and post-leach chemical leakage. In particular, ammonium bicarbonate, the commonly-used leach solution, was examined in great detail. Agitation leach tests were conducted to examine the effect on ammonium sorption and desorption of clay content, solution and clay ammonium levels, pH, and the type and concentration of other anions and cations in solution. Initial column tests were performed to determine the degree of ore-aquifer interaction that could be expected for various leach solutions; sulfuric acid, and ammonium, sodium, and potassium bi-carbonates. Subsequent tests examined various methods to restore the ores by lowering the post-leach chemical leakage. The restoration tests examined the use of reducing agents (e.g., ammonium bisulfite, sodium bisulfite; and sodium sulfite), ore blocking and stabilizing agents (e.g., sodium silicate, aluminum chloride, and magnesium-calcium salt).and ammonium displacement agents (e.g., aluminum chloride and lanthanum chloride-sulfate)

Jan 1, 1980

By Evelio N. Horta

The influence of soil improvement replacement area in foundation settlements is discussed for soil improvement methods used in Southeast Florida. A 3D Finite element analysis is used for two typical conditions in the area: foundations bearing on loose sands and foundations bearing on a crust of limestone underlaid by very loose sands. Particular attention is given to Jet Grouting as a soil improvement method. The potential impact of the stiffer jet grout columns on the structural foundation design and quality control issues are also discussed. It is shown that in loose sand conditions 15 to 20% area replacement produces substantial reduction in total settlements. Reduction in total settlements for mixed profile is less significant but the use of the method in those cases is directed to reduce punch through potential.

Jan 1, 2007

By Thomas M. Brady

The Spokane Research Laboratory/NIOSH and the University of British Columbia (UBC) geomechanics group are focusing on the development of safe and cost-effective underground design guidelines for weak rock masses having an RMR in the range of 15 to 45. Weak ground conditions, ground support, and mining methods used in several North American underground mines were observed. The RMR values were calculated to update both manned entry span design and non-entry stability graphs, plus a database on underhand mining methods was created to reflect existing North American mining conditions. The immediate rock mass was characterized and analyzed in terms of prevailing type of ground support, potential failure mechanisms, and rock behavior to define how existing design curves must be modified for the existing weak rock mass. The current NIOSH research attempts to provide rock mechanics tools to assist a mine operator in making sound economic decisions that will also ensure a safe working environment.

Jan 1, 2006

By José Fernandes De Oliveira Ugarte

El presente texto describe los resultados de la caracterización mineralógica de muestras minerales de cobre que fueron empleados en el proceso de flotación. Para este proceso, fue necesario conocer la mineralogía de diferentes minerales de cobre de yacimientos tipo pórfido, así como sus asociaciones con los estudios mineralógicos y estudios geoestadísticos por microscopia electrónica de barrido con el sistema de energía dispersiva.

Feb 1, 2014

By R. W. Smith, A. M. Raichur, M. Misra

Mycobacterium phlei has very good potential as a hematite flotation collector. The flotation recovery of hematite is dependent upon the solution pH and concentration of the microorganism. The critical pH for maximum recovery of hematite is around three, which corresponds to the point of zero charge of the microorganism. An excellent correlation between the flotation recovery and bacterial adhesion on hematite is observed. The adhesion of Mycobacterium phlei on hematite can be described by the potential energy of interaction calculations using an extended DLVO theory.

Jan 1, 1994

By Erika Baêta e Souza

Essa frota é fundamental em função da flexibilidade de produção. No entanto, o produto da manutenção é a disponibilidade física (DF), que é o tempo disponível para o equipamento operar. Assim, desenvolveu-se um trabalho de seis sigma voltado para a disponibilidade física (DF) da frota, que não estava no patamar esperado. O trabalho foi desenvolvido através de ferramentas de análise e solução de problemas, no período de Jan/12 a Ago/12. A DF média da frota era 68,5% sendo o benchmark interno de 72%. As ocorrências de parada foram agrupadas por sistemas utilizando o critério de similaridade. Após isso foram utilizadas ferramentas de priorização dos focos mais relevantes encontrados. Para estes focos foi feita análise de comportamento no tempo e variabilidade com intuito de encontrar as causas fundamentais para ocorrência dos eventos. As causas foram classificadas e priorizadas e as ações foram então definidas e implantadas. Foram monitorados os indicadores MTBF, DF e considerado o aspecto financeiro. Estabeleceu-se uma rotina de gestão e padronização de processo como forma de alcançar o resultado. Ao fim do trabalho, foram plantadas as sementes dos bons resultados colhidos desde então, chegando a DF de 74,1%.

Aug 8, 2018

By Akihide Hosokawa

The void growth and coalescence in model materials involving a pre-existing three dimensional void array (i.e. multiple layers of a void array) was studied by X-ray computed tomography (XCT) coupled with in situ tensile deformation. To reduce the recording time, a new technique called fast tomography was employed. The model materials used in this paper were fabricated by the combination of an ultra-short pulsed laser machining system and a diffusion bonding technique, and two different types of arrays were prepared namely, FCC 1 and FCC 2 type array. This methodology allowed the authors to capture the entire process of growth and coalescence events of a void array embedded in the metal matrix. The failures in the both materials involved internal necking and shear localization. One of the highlights of this paper is that the plastic strain at the onset of void coalescence was measured for each model material. These values are in fact the adequate values to be compared with the coalescence strain predicted by existing void coalescence models such as the Brown and Embury model, the Thomason model and the Pardoen and Hutchinson model. The comparison suggested that the Brown and Embury model underestimated the coalescence in neither of the current model materials, while the Thomason model and the Pardoen and Hutchinson model showed a quite good agreement with the result for FCC 1 material. On the other hand the result from FCC 2 material agreed with none of the models probably due to the geometry of the void array that is not compatible with the existing models.

Jan 1, 2010

I. Domestic Production and Use: In 1981, 13 companies operated 32 primary aluminum reduction plants, with 3 firms accounting for 58% of production, Washington, Oregon, and Montana accounted for 32% of the total production; Texas, Louisiana, and Arkansas 16%; Tennessee, Alabama, South Carolina, and North Carolina 17%; other central and eastern States 35%. Based on published producer prices output of primary metal in 1981 was valued at over $7.5 billion. Aluminum consumption by 25,300 firms was centered in the East Central United States. Packaging accounted for an estimated 30% of domestic consumption in 1981, building 21%, transportation 18%, electrical la%, consumer durables 8%, and other uses 13%

Jan 1, 1982

By Edison Roberto Celis

El presente trabajo señala la posibilidad de ocurrencia de accidentes graves y fatales en relación con los riesgos que se evalúan durante la aplicación de la estrategia de control. La estrategia incluye una selección de actividades, lugares, personas y equipos que deben ser incluidos en el proceso, y se basa en una evaluación previa de la data de seguridad existente en la operación, para estimar las direcciones probables de aplicación de la herramienta. Finalmente se elabora un mapa coloreado de probabilidades que permiten al gerente analizar y decidir el inicio del control de la probabilidad de accidentes graves.

Sep 12, 2011

By George Goble

I hope that after the long evening and all the exercise that some of you took you won't be completely exhausted to listen to a little bit about pile testing. The topic that 1 have been given is pile testing. It seems to me useful to break this topic into some smaller pieces so that we can try and organize our thought a bit. As I understand the terms "pile testing", I believe we are really referring always to capacity, one way or another, so I am suggesting that we organize the things we are doing in terms of measurement of soil capacity and pile capacity. There are obviously two failure modes and we frequently speak of pile integrity rather than structural pile capacity, but it's really capacity that we are concerned about. Further within these breakdowns I am suggesting that we might look at the topic of soil capacity in terms of static methods and dynamic methods and, finally, within each one of these, measurements of axial capacity and measurement of lateral capacity. Also here some of these subdivisions might be there for the purpose of symmetry and finally the same sorts of breakdown in Pile Capacity area.

Jan 1, 1994