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By Chris L. Powell, Russell J. Denny

"The remotely located Cockatoo Island iron ore mine off the Kimberley coast in the northwest of Western Australia has been in operation since 1951. The mine was recently expanded up to about 50 m (165 ft) below sea level using staged construction to create a rockfill seawall around the open cut mining operation. Late in 2013, to allow expansion of subsea iron ore mining operations, Wagstaff Piling was engaged to install a seepage barrier through the rockfill seawall and into the underlying seabed sediments.Earlier stages of seawall construction had used a variety of different construction techniques with varied success, and the history of subsea mining on the island had been plagued with failures, including failures in the slope of the seawall itself, hanging wall failure underneath and inside the seawall, and footwall failures as the ore was mined leaving the rock face inclined at 55 degrees, parallel to the bedding. The current expansion, known as the Stage 4 expansion, was more tightly constrained by the pit geometry and available materials than previous seawall expansions that adopted clay core and sheet pile seepage barrier solutions. In Stage 4, an innovative seepage barrier solution using a grout curtain was selected to provide the necessary cutoff to allow access to high-grade ore, while protecting the mine from inundation by the sea.Seawall ConceptThe open cut subsea mining operation consisted of a 3 km (1.9 mi) long narrow pit along the south side of Cockatoo Island that extended to depths of about 50 m (165 ft) below sea level, and were exposed to the open sea on the south side of the pit. Massive tidal variations of more than 10.5 m (34.5 ft) required a seawall founded on the seabed, extending upwards to RL+13, to safely protect the pit from the high tide level rising to above RL+10."

Jan 1, 2017

By Chris L. Powell, Russell J. Denny

"The remotely located Cockatoo Island iron ore mine off the Kimberley coast in the northwest of Western Australia has been in operation since 1951. The mine was recently expanded up to about 50 m (165 ft) below sea level using staged construction to create a rockfill seawall around the open cut mining operation. Late in 2013, to allow expansion of subsea iron ore mining operations, Wagstaff Piling was engaged to install a seepage barrier through the rockfill seawall and into the underlying seabed sediments.Earlier stages of seawall construction had used a variety of different construction techniques with varied success, and the history of subsea mining on the island had been plagued with failures, including failures in the slope of the seawall itself, hanging wall failure underneath and inside the seawall, and footwall failures as the ore was mined leaving the rock face inclined at 55 degrees, parallel to the bedding. The current expansion, known as the Stage 4 expansion, was more tightly constrained by the pit geometry and available materials than previous seawall expansions that adopted clay core and sheet pile seepage barrier solutions. In Stage 4, an innovative seepage barrier solution using a grout curtain was selected to provide the necessary cutoff to allow access to highgrade ore, while protecting the mine from inundation by the sea.Seawall ConceptThe open cut subsea mining operation consisted of a 3 km (1.9 mi) long narrow pit along the south side of Cockatoo Island that extended to depths of about 50 m (165 ft) below sea level, and were exposed to the open sea on the south side of the pit. Massive tidal variations of more than 10.5 m (34.5 ft) required a seawall founded on the seabed, extending upwards to RL+13, to safely protect the pit from the high tide level rising to above RL+10."

Jan 1, 2017

By Eric E. Cather

A mineral survey of the Fisher Gulch RARE II area (A5299), Trinity County, California was conducted by the U.S. Bureau of Mines and U.S. Geological Survey. The Bureau of Mines was responsible for detailed examination of mines, prospects, and mineralized zones; the Geological Survey conducted geological, geochemical, and geophysical studies of the area. The area is underlain by the Salmon Hornblende Schist. Tonalite stocks 1.5 mi (2.8 km) to the east and northeast of the area intrude the schist and are closely associated with the nearby nines (Cox, 1967). The mines have quartz veins containing sulfides and gold in shears trending east to north past in the schist and tonalite (Hotz, 1972). Strewn and terrace gravel s occupy most of the drainages, many have yielded substantial quantities of gold.

Jan 1, 1981

By John B. Tieder

Arbitration is a legally recognized alternate litigation for the resolution of civil disputes. The parties agree, either before or after a dispute arises, to submit that dispute to an independent third party for resolution. The decision of that third party is binding on the parties. A decision of an arbitral tribunal, typically referred to as an "award," cannot be reviewed by a court except on very limited grounds, such as fraud. See, e.g., Va. Code 8.01-581.010. Indeed, an arbitral award is typically less subject to judicial review than the decision of a trial court, whose decisions are almost always subject to appellate review as a matter of right. Arbitration is typically the result of a contractual agreement between the parties to submit disputes to arbitration. On occasion, arbitration can be required by statute. For example, the California Department of Transportation requires the arbitration of all disputes arising under its contracts. Public Contract Code, Article 7.1 (§§10240-10240.13). There may be a question whether statutorily required arbitration is truly arbitration or an administrative law disputes resolution procedure. The significance of the difference is that the decisions of administrative law bodies are typically reviewable by a court of law as a matter of right while, as set forth above, arbitral awards are almost never reviewable.

Jan 1, 1988

By Francis J. Arland

The installation of augered cast-in-place (ACIP) piles requires careful quality control to assure a successful pile installation. Unlike steel, pre-stressed concrete or other types of driven piles, which are shop fabricated, delivered to the site and typically driven to a minimum tip resistance, augered cast-in-place piles are installed to a pre-determined tip elevation or to a refusal criteria. The structural section of the ACIP pile is constructed during pile installation and cannot be inspected prior to installation. Therefore, a carefully administered quality control program is essential to a pile foundation that will meet or exceed design requirements. This requires an experienced team consisting of the Geotechnical Engineer, Contractor and Inspector. The focus of this paper is to discuss the responsibilities and duties of the ACIP piling Inspector. Qualifications of the Inspector The qualifications of the inspector are related to the complexity and difficulty of the proposed project. Ideally, the Inspector should be an individual with a degree in civil engineering with special emphasis in geotechnical engineering. A properly trained technician with geotechnical engineering experience working under the direct supervision of a geotechnical engineer may be able to provide competent inspection on some projects. It is important that the Inspector have a good understanding of subsurface and ground water conditions and how they will affect pile installation. The Inspector must understand ACIP pile installation procedures and be able to communicate with the Contractor, Structural and Geotechnical Engineers; and maintain a detailed pile record for each installed pile.

Jan 1, 1997

By Fred D. Fox

Introduction Abandoned mill tailings deposits can be found throughout the northern Black Hills of South Dakota, indicative of mining activities that originated during the great gold rush days of 1875. The Refuse Act of 1899 attempted to regulate the deposit of debris from mines and stamp works. But, in most cases, huge volumes of mine and milling wastes were disposed of in ways no longer considered environmentally acceptable. Restoration of gold mill tailings deposits is a relatively new practice to the Black Hills area. This discussion will present an overview of the environmental setting, environmental problems associated with past tailings disposal practices, practices being implemented to solve these problems, and prospects related to present the future tailings disposal practices. Environmental Setting An understanding of climatic characteristics, geology, surface and ground water hydrology conditions, and the physical and chemical characteristics of selected mill tailings deposits will aid in understanding environmental problems associated with tailings disposal and restoration. Climate The Black Hills region is in the middle latitudes, which have a

Jan 11, 1984

By Richard W. Hanford

The geotechnical construction industry generally considers soil mixing to be defined as an in situ ground improvement or treatment method by which a dry or wet reagent is introduced into the ground and is blended with the soil by mechanical or rotary mixing tools. This results in relatively homogenous mixtures whose engineering properties are improved and are greater than the soil properties before mixing. Reagents usually include cement, but may also include processed clay such as bentonite, when a reduction in hydraulic conductivity is desired, or other proprietary chemicals when chemical stabilization is the objective. Mixing may be either shallow or deep. Shallow Mixing is the term arbitrarily used for treatment of soils within the upper 30 feet; Deep Mixing denotes treatment below 30 feet to the depth limits of the equipment. Mixing equipment may consist of single or multiple-shaft tools having cutting and mixing blades of many different configurations. To avoid using proprietary nomenclature, reference to Shallow Mixing Methods (SMM) and Deep Mixing Methods (DMM) are the preferred terms. Although originally developed and patented in the United States in 1956, in situ construction using various soil mixing methods is more prevalent in Japan and the Scandinavian countries. Reintroduced into the United States from Japan in 1986 for ground improvement and liquefaction mitigation at Jackson Lake Dam, Wyoming, acceptance of soil mixing methods has been gradual but slow. Applications typically include:

Jan 1, 2001

The New Zealand microcontinent is relatively well endowed with gold deposits; its past gold production per unit area of 3.2 kg/km2 ranks high on a world scale. Total recorded production (1857 - 1986) is about 854 000 kg and most of this gold was mined between 1861 and 1920. There has been a strong revival in gold exploration and mining since 1979, with exploration expenditure of around $15 million per annum and a declared gold production in 1986 of 1265 kg (886 kg in 1985). In addition to numerous alluvial gold recovery plants working small to medium sized deposits (mainly in Westland and Otago), there are five medium to large projects that have started production (Martha Hill), or have reached advanced stages of construction (Grey River dredge), permitting (Golden Cross and Macraes) or exploration (Globe-Progress). This summary paper is taken from reviews by Brathwaite et al (1986) and Brathwaite (1988).

Jan 1, 1988

Construction work on one of the world's largest landslide stabilisation projects is drawing to a close in Central Otago. Begun in mid 1990, major stabilisation work has been carried out on seven large rockslides which will be partially inundated when the Clyde dam reservoir (Lake Dunstan) is filled. The work has required the construction of 14.5 kilometres of tunnel, 60 kilometres of surface drilling, 78 kilometres of drilled drainage holes and five million cubic metres of earthworks. The stabilisation programme has been carried out by the Electricity Corporation of New Zealand as part of the Clyde Power Project, a hydroelectric development on the Clutha River.

Jan 1, 1992

By H. Do, R. Yoon

Mineral flotation is effective over a relatively narrow particle size range of approximately 10 to 100 µm. If the upper particle size limit can be increased, however, a run-of-mine ore may be coarse ground, and only the middlings are ground further to achieve required grades. This will result in significant energy savings and increased throughput. In this communication, methods of increasing the upper particle size limit will be discussed on the basis of a flotation model that can predict flotation from both hydrodynamic and surface chemical parameters. An example of increasing flotation recovery by control of a chemistry parameter is given.

Jan 1, 2007

By Wenbing Guo

The stability of strip pillar is the key to successful strip pillar mining. In analyzing the stability of the strip pillar, the width of yield zone must be determined. The determination of the width of yield zone has been an important subject for researchers. In this paper, the numerical method was used to study the relationship between the width of yield zone in strip pillar and coal recovery ratio. The results showed that as the recovery ratio increases, the width of yield zone increases exponentially. Accordingly, the formula for determining the width of yield zone was updated and the effect of changing coal recovery ratio on strip pillar deformation is presented.

Jan 1, 2006

By M. Kuchta, A. Newman

LKAB’s Kiruna Mine, located above the Arctic Circle in northern Sweden, is the second-largest underground mine in the world today. The orebody is a world-class high-grade magnetite deposit, from which three raw ore products are extracted. We use mixed integer programming to determine a production schedule, i.e., which production blocks to mine, and when to start mining them, so as to minimize deviation from planned production quantities while adhering to the operational constraints of the mine. The resulting model contains thousands of binary variables and a commensurate number of constraints, precluding us from obtaining a schedule in a reasonable amount of time. We describe a method that builds on prior, related work, to expedite solution time. Keywords: underground mining, production planning, optimization, integer programming

Jan 1, 2003

The Mining Foundation of the Southwest will host its 24th Annual American Mining Hall of Fame Awards Banquet at the Tucson El Conquistador Golf & Tennis Resort in Tucson, AZ on Saturday, Dec. 9. The Mining Foundation of the Southwest is a non-profit organization whose objectives are public education about the mineral industries. It also recognizes outstanding accomplishments in and contributions to the fields of fuel and mineral resources.

Jan 1, 2006

The mining industry continues to experience a skills shortage and this is having an impact on the ability of mining companies to operate sustainably. Apart from a few exceptions, there is a dearth of geologists, mining engineers, metallurgists as well as environmental scientists and other professionals in the global mining industry. This relates to both quantity and quality. It makes good business sense for mining companies to employ local professionals rather than expensive expatriate staff. In some cases a mining company could employ more than 10 local mining engineers for the cost of one expatriate. However, in many countries local professionals are not always equipped professionally to work on mine sites. The result is that many companies are not operated optimally due to human resources gaps. In some cases, particularly in key areas such as mine planning, this threatens the sustainability of the operation or at the very least results in sub-optimal resource utilisation. This paper briefly presents some of the issues and strategies being implemented and that might be implemented to maintain a sustainable supply of quality minerals graduates to the industry in 2011 and beyond.

Jan 1, 2011

By D. Boldini, R. Lackner, H. A. Mang

ABSTRACT: In this paper, the strong interaction between the hardening shotcrete lining and the surrounding ground in NATM tunneling is investigated by means of axisymmetric analyses, accounting for the three-dimensional nature of the excavation process. The effect of the hydration of shotcrete on strength, stiffness, chemical shrinkage as well as microcracking and creep are accounted for. For the description of the mechanical behavior of the ground, a multi-surface plasticity model is employed. The performed analyses of the excavation process provide insight into the influence of each phenomenon accounted for in the material model for shotcrete on the response of the ground-shotcrete compound structure. ZUSAMMENFASSUNG: In diesem Beitrag soll die Interaktion zwischen dem erhärtenden Spritzbeton und dem Boden auf der Basis axisymmetrischer Berechnungen untersucht werden. Derartige Berechnungen ermöglichen die Berücksichtigung des drei-dimensionalen Charakters des Vortriebprozesses. Die Auswirkung der Hydratation auf die Entwicklung der Festigkeit, Steifigkeit und der chemischen Schwindverzerrungen, sowie das Reißen und das Kriechen des Spritzbetons wurde berücksichtigt. Das mechanische Verhalten des Bodens wurde mittels eines Mehrflächenplastizitätsmodells simuliert. Die durchgeführten Berechnungen des Vortriebprozesses geben Einblicke in die Auswirkungen der Spritzbetoneigenschaften auf das Tragverhalten des Boden-Spritzbeton-Komposits. RÉSUMÉ: La stricte interaction entre le soutènement en béton projeté durcissant et le terrain dans un tunnel creusé avec la NATM est étudiée par des analyses axisymétriques, compte tenu de la nature tridimensionnelle des processus de creusement. Les effets de l’hydratation du béton sur la résistance, la rigidité et la contraction chimique, ainsi que sur la micro-fissuration et le fluage, sont mis en compte. Pour la description du comportement mécanique du terrain on emploie un modèle de plasticité multi-surface. Les analyses conduites mettent en évidence l’influence de chaque phénomène considéré dans le modèle constitutif du béton projeté sur la réponse de la structure composite terrain-béton projeté.

Jan 1, 2003

As longwall shields are lowered in preparation for advance, dust from the canopy falls directly into the air stream with the potential of becoming entrained. Historical dust sampling data from the early 1980s shows that shield advance contributed an average of 12 percent to the airborne respirable dust levels found on longwalls in the United States. Data from the 1990s indicates that shield dust liberation had increased to an average of 23 percent. Increased longwall production levels over this time resulted in the need to move a larger number of shields during each shift, while an increase in air velocities on the face was also occurring. These factors combine to suggest that greater quantities of shield dust are being entrained into the face air. A series of controlled laboratory tests were conducted in a test stand simulating shield dust entrainment to evaluate changes in airborne respirable dust levels at different air velocities. Significant differences in respirable dust entrainment were observed. The test facility, test methodology, and dust sampling results will be reviewed and discussed

By Morteza Gharouni Nik

Flexible Dilatometer Test (FDT) is one of the in-situ test methods for determining the deformational characteristics of rock masses. In this study, several dilatometer tests have been conducted in different geotechnical phases of site investigations by means of two types of FDTs. The purpose of this paper is comparison of the performance of these two types of dilatometers and analysis of the differences in the results of the tests.

Jan 1, 2008

By Paul Downing

When was the last time the documents and paperwork were cleaned out of the glove boxes, door pockets, under the seats and above the visors in your company vehicles? Insurance cards that expired three years ago and vehicle registrations from 1999 through 2003, for instance, don’t do any good and just take up space

Jan 1, 2008

This paper is concerned with the blasting of rock in mining. The most common purpose of blasting rock is to cast it or to disrupt its structure sufficiently for effective digging and subsequent removal.

Jan 1, 1991

By D. L. Stevens

Following an in-depth scenario and strategic planning exercise in 1997, Noranda’s mine production goal was set at 500,000tonnes per year of both copper and zinc metal within five years. There had been no recent discoveries, reserves were shrinking and things had to be done differently and quickly. Change is now continual in our program but here is what we did first: - Combined the exploration and business development groups - Formed teams to search for and respond to opportunity - Made our geologists more business minded and our engineers more optimistic - Went global - Set clear thresholds, farmed out the marginal properties, fast tracked the others - Focussed reconnaissance exploration where we had a clear competitive advantage - Became a “flexible” partner to both juniors and seniors

Jan 1, 1999