Search Documents

By D. Craig Camp

Microtunneling has successfully completed both horizontal and vertical curves. This paper covers the historical development of curved microtunneling and a description of one microtunneling project. The completed microtunnel is used for electrical transmission in Japan. The crossing had several concerns including right of way, social disruption, obstructions, the cost of intermediate shafts, and political restrains. In order for this drive to meet all of the imposed restrictions, four horizontal curves and one vertical curve were planned and executed in accordance with the design. Iseki Poly-Tech of Tokyo, Japan designed and built the microtunneling machine to meet the project requirements. Curved microtunneling has been successfully used on fourteen projects in Japan. The reason for a curve has been that the project could not be rerouted, short straight drives could not be used to negotiate the curve, or the project’s social and environmental conditions required a curved tunnel. The following table (Table 1) includes summary information on 14 curved microtunnling projects that have been successfully completed in Japan. The first column is a reference number. Columns two through four include basic project information. The fifth column is the total project distance completed by microtunneling. The sixth column is the project’s microtunneling duration. The seventh column is the machine type and size. All of the machines listed are manufactured by Iseki Poly-Tech of Tokyo, Japan. The size is the internal concrete pipe diameter; all of the projects listed were completed with Japanese standard concrete pipe. The eighth column contains a general description of the soil. The soil type and blow counts are approximately equal to ASTM D 2487 standards. The ninth column lists the radius of the curve and the span distance or the distance microtunneled that included the curve. The radius of a vertical curve is denoted with a “VR”, a span with both a left and right hand curve is denoted with a “S”. Other significant first events are also noted in this column. The first curved microtunneling project was completed in 1982 using a conventional microtunneling machine with standard Japanese concrete pipe and a very long radius curve while maintaining grade for the gravity sewer. The second curved microtunneling project included multiple radii curves, all in the same direction, on a single drive. In 1989, on the fifth curved microtunneling project, a “S” curve was successfully negotiated. On the seventh curved microtunneling project, completed in1995, a tight radius curve was negotiated. In 1996, the eighth project included a vertical curve. The thirteenth curved microtunneling project, completed in 1997, was the first project to utilize a microtunneling machine specifically designed to negotiate curves. The fourteenth curved microtunneling project was the accumulation of all

Jan 1, 2001

By Duk-Won Park

Since geologic anomalies are one of the governing factors of instability of underground openings, it is extremely important to know in advance the locations and extent of these anomalies such as faults and weak zones. At an underground coal mine in the Black Warrior Basin, core drilling was conducted to find a fault in an area where they were planning to locate longwall panels and possibly a shaft. Core logging did not provide sufficient information to delineate the exact location, strike, and dip of the fault. However, a high resolution reflection seismic study successfully solved this problem. This experience proved the seismic exploration technique could be used for premining coal exploration by reducing drilling costs and providing more accurate and detailed information about geologic anomalies.

Jan 1, 1988

By H. Zhu

Qualitative and interpretative information as obtained from geological and/or geophysical studies, in addition to precise measurement, is incorporated into the estimation process through an indicator variable. The indicator conditioned estimator is formulated as a cokriging and its expression is data value dependent as opposed to that of the traditional kriging estimators. The solution of the dual cokriging system pro-vides simultaneously an estimate of the unknown and an estimate of the conditional probability that the unknown belongs to a specific population or class. Being an unbiased and minimum-error-variance estimator by construction, the indicator conditioned estimator is better in the least square sense than the ordinary kriging estimator because it uses additional information carried by the indicator data.

Jan 1, 1989

By S. Koro

The current economic climate of low commodity prices and increasing costs has put a lot of pressure on mining companies to ensure their operations will survive through the current economic downturn. While history tells us that the cycle will turn around and prices will go back up again, how many mining companies will be left to take advantage of the next upturn? On average in Australia, the maintenance of mining equipment accounts for up to 50% of operating costs; which equates to nearly $15bn per year. In addition to trying to boost productivity, mining companies are also putting a lot of pressure on reducing costs; all with the intention of maintaining/increasing profit margins and thereby keeping shareholders ?happy?. The whole premise of our economy is based on ?growth? and ?profits?. Movements in the market place force mine owners to ?react? to short term fluctuations. And if that movement is downward; operations people at the sites are forced to start reducing costs. Is this cost reduction done in a logical, systematic way where all risks (short-, medium- and long term) are considered? Invariably, the answer is no! Short term ?fixes? are normally implemented with little, or no, regard for medium- and long-term impact. And the reason for this is that management is not fully focused on the long term; focus is mainly on survival. Decision making is driven by shareholder sentiment and history tells us that this is largely short-term. So given these paramteres to work within, what role can ?Asset Management? play in assisting management to meet shareholder and market requirements whilst still maintaining long-term viability of their operations (to the long-term benefit of shareholders dare I say). As maintenance costs account for nearly half the operating costs of mining companies; the ?smart? management of assets is not only crucial; it is essential for survival in today?s economic climate. What is asset management? Asset Management, according to the UK-based Institute of Asset Management (IAM) is ?the systematic and coordinated activities and practices through which an organization optimally and sustainably manages its assets and asset systems, their associated performance, risks and expenditures over their life cycles for the purpose of achieving its organizational strategic plan.? How important is asset management in today?s mining companies? IAM goes on to say: ?This definition of asset management represents a significantly greater scope than just the maintenance or care of physical assets, and is closer to the central purpose of an organization. Good asset management considers and optimizes the conflicting priorities of asset utilization and asset care, of short-term performance opportunities and long-term sustainability, and between capital investments and subsequent operating costs, risks and performance. ?Life cycle? asset management is also more than simply the consideration of capital costs and operating costs over pre-determined asset ?life? assumptions. Truly optimized, whole life asset management includes risk exposures and performance attributes, and considers the asset?s economic life as the result of an optimization process (depending upon the design, utilization, maintenance, obsolescence and other factors).?

Feb 23, 2014

By David J. Hatem

Tunnels and underground projects are inherently more risky than vertical projects, which typically utilize more conventional design and construction approaches and are undertaken in the context of relatively ascertained and defined conditions. On tunnel and under-ground projects, there are a host of special risk factors, including unknowns and uncertainties as to the physical and behavioral characteristics of the ground, the inextricable interdependence and necessary interaction of design decisions and construction means and methods with those ground conditions as well as the manner in which risks are allocated among project participants for un-anticipated subsurface conditions. Public-private partnerships (PPP) projects, in their own respects (and independent of any major subsurface component), pose significant risk for all private sector participants. The main driver of owners to procure projects using PPP is financial, as often all, or substantially all, of the design and construction risk are transferred to the private sector consortium, including the design-build (D-B) team. For a concerning number of those public owners, that risk transfer regime includes rather onerous and aggressive contractual terms that allocate to the private sector participants substantially all risks associated with the encountering of unanticipated subsurface conditions. These aggressive risk allocation provisions, while directly impacting project participants upstream of the consulting engineer, have an indirect and corresponding risk intensifying effect upon consulting engineer professional liability exposure. There are many factors that result in increased professional liability exposure for consulting engineers involved in PPP projects. The more prominent and prevalent of those factors fall into the following categories:

By D. Kump

The Bullfrog Mine is an underground goldmine that uses the underhand-cut-and-fill mining method. The portal was established on June 18, 1991. Mining is expected to be completed by the summer of 1999. This paper starts by discussing what it took to get from nothing to 2000 tons-per-day backfill, and ends with a hindsight commentary on things that did and did not help.

Jan 1, 1999

By D. D. Potter

ABSTRACT OF ORAL PRESENTATION Extraordinary conditions are often encountered when designing large blasts for in situ mining methods and spatial or innovation techniques are sometimes required. Some of the considerations in designing these large blasts will be discussed with emphasis on those factors that concern powder factor, rock movement and fragmentation. Sources of basic data will be described, along with some of the methods for obtaining these data.

Jan 1, 1977

By Jess H. Albino, Girish Roy, James M. Monsees

Construction of the North Hollywood line of the Los Angeles Metro System required crossing the Hollywood Fault as the twin transit tunnels extend into the San Fernando Valley. The Hollywood Fault is considered active and represents the largest active fault that the North Hollywood Redline extension will cross. The feature is a thrust fault with the north plate overriding the southern plate and creating the Santa Monica Mountains in the process. South of the fault lies the alluvial valley and Hollywood. North of the fault are the Santa Monica Mountains which rise locally to more than 1200 feet. The average overburden at the seismic section is about 300feet and is overlain by Runyon Canyon Park, a municipal park with environmentally sensitive areas. The actual fault plane was anticipated to lie within the southernmost120 feet of the 600 to 700-foot-wide fault zone. The special seismic section constructed for the tunnels consisted of an enlarged cross-section with special lining, drainage and finish features that will facilitate the restoration of metro service in case of a major event occurring on the Hollywood Fault. The discussion will address the geology, the procedure used to define the design event and predicted displacements, the unique design features as well as the construction methods used and the instrumentation and the results obtained.

Jan 1, 1999

By E. Bonates

Truck/shovel systems are a major form of materials handling in open-pit mines in spite of the high associated capital and operating costs. Mine management is usually faced with a decision to purchase new equipment in order to support the steadily increasing on production. These decisions involve a high degree of uncertainty with respect to future demands and technical developments. This paper describes a computer simulation model for evaluating the optimum equipment fleet in an open-pit mining operation. The system is based on a stochastic simulation program which accounts for the various mining and economic parameters. It calculates the type of equipment and the optimal number of trucks needed to meet the production targets. Two types of selection criteria: maximum rate of production or minimum cost can be applied.

Jan 1, 1989

By G. L. Merritt

The implementation of the Surface Mining Control and Reclamation Act of 1977 (SMCRA) has evolved into one of the most complex environmental protection programs to come out of the late 1970's. The level of detail in the statute and the regulations have resulted in a rigid and complex set of requirements for the administration, permit-ting, inspection and enforcement of the program. In addition, the constant change of the federal program caused by regulatory changes, reorganization of the Office of Sur-face Mining Reclamation and Enforcement (OSMRE), ongoing litigation involving OSMRE, and the use of the budget to establish additional mandates on OSMRE and the State Regulatory Authorities have resulted in an unstable program. The instability of the program makes it extremely difficult for the States to implement their programs and to achieve the goals of SMCRA.

Jan 1, 1988

By A. Ghalambor

The objective of this investigation was to determine the sensitivity of three selected input parameters in the operational control of continuous bottom-fed thickeners used for the treatment of coal refuse slurries. The three variable parameters were "Feed Flow Rate," "Feed pH," and "Feed Solids Concentration." These three input parameters were studied under three polymeric conditions which were cationic polymer, anionic polymer, and a combination of cationic-anionic polymer. For each polymeric condition, two mathematical models were developed: one for overflow response, the other for underflow response. The combination polymers produced the best desired quality of overflow and underflow. For this polymeric condition, changes in the feed solids concentration was the most sensitive factor in the maintenance of the overflow quality, and the feed pH was the most sensitive factor for the maintenance of the underflow quality. The mathematical models generated a set of plots which would allow an operator to control and/or adjust any of the three variables to achieve optimum conditions.

Jan 1, 1989

By G. E. Slagel

On August 3, 1987, a hearing was held by the House Subcommittee on Energy and the Environment to commemorate the tenth anniversary of the Surface Mining Control and Reclamation Act (SMCRA). Four panels of environmental/citizen group representatives went before the Subcommittee to report on the state of affairs (from their perspective) of the coal industry and the Office of Surface Mining, Reclamation and Enforcement (OSMRE) As expected, these groups had little positive news to report and continued to focus on glaring deficiencies within the surface mining program. They indicated that gross abuse of SMCRA has continued over the past ten years and the states have performed poorly. Congressman Udall's opening comments perhaps best characterized the mood of the group with his statement that "The Act has not accomplished what I or the people of the coalfields had hoped." and " ? a segment of the coal industry has continued in its bitter and implacable opposition to the most basic of environmental controls."

Jan 1, 1988

By Timothy J. Haddon

For the mining industry in general and gold mining in particular, the past few years have been difficult. Economic conditions, coupled with growing regulatory restrictions, have led to increasingly important reasons for managing assets wisely. From a public company perspective, such asset management makes sense because it ultimately provides for an increase in shareholder wealth, and that is why we are in business. Regardless of whether a company is public or not, assets must be managed effectively to remain a player in today's competitive environment. So, as the chief executive officer of a gold mining company, how do we manage our assets to ensure that we are satisfying our obligations to our customer-the Amax Gold shareholder? The gold industry has been under siege. We have just completed the third year with average prices below $12.85/ g ($400/oz). When finding, and/or acquisition costs and development costs to operating costs are added, there isn't much of a profit margin left. What this environment provides, however, is opportunities for growth. In the gold business, you either grow or you die. Today, most North American gold producers have, at most, a 10-year mine life. We are all scrambling to add reserves so we do not become extinct. As prices remain low, opportunities abound for increasing diminishing reserves. This is the time for the opportunistic company to take advantage of market conditions and that is precisely what Amax Gold has done. There are six components to running a successful gold business: • finding reserves through exploration, acquisition or joint venture, • financing the project, • permitting and constructing the project, • operating the project, • cash management and • communication.

Jan 1, 1992

By L. Adler

Existing classifications of mining and construction equipment have had major deficiencies. They often lack organization, balance, and have remained obscure. Particularly when proceeding to great.er resolution these deficiencies have proven crippling. By adopting "Classes", "Groups" f "Types" and "Kinds" at successive degrees of refinement, a "Taxonomy" is developed based on clear visual differentiation or on a "Morphology??. This symbiotic application, adopted from the Biological Sciences, yields clear, simple and unambiguous results. Supporting this effort are guidelines for easily and credibly sketching equipment which are also distinctive. Numerous illustrative examples are provided. Communications are improved and the engineer obtains a confident feel for the equipment at hand.

Jan 1, 1989

By Terry Mudder

Long-term anaerobic biochemical treatment for draindown of residual solutions is a cost-effective way to close a heap-leach pad. This article presents a laboratory evaluation of anaerobic biochemical treatment of cyanide heap-leach pad solutions. The traditional approach to heap-leach pad closure is to rinse the pads with multiple pore volumes of fresh or recycled treated water. The effluent from an initial rinse is often treated and recirculated until the solutions passed through the heap meet the appropriate numeric and narrative water quality standards. Column rinsing tests are completed during project planning to determine the number of pore volumes of fresh or recycled treated water required to rinse the pad to meet long-term closure requirements. A traditional closure plan generally includes provisions to sample the rinse effluent and rinsed solids (the Meteoric Water Mobility, Procedure or USEPA 1312) to verify that chemical requirements are being met.

Jan 1, 1995

The tungsten carbide insert bit has probably advanced blasthole drilling more than any other single improvement. Tungsten carbide inserts have longer life, maintain sharper edges, and penetrate faster than hardened steel edge bits. Before the tungsten carbide hit appeared, all-steel bits were used. Even with the new bits, blasthole drilling costs vary with the type of equipment used and its condition; the hole's length and diameter; the rock's texture, hardness, and nature; the operator efficiency. To help reduce drilling costs, the operator should be familiar with the use and care of drill bits. This article provides information about tungsten carbide rock bits used for percussion drilling. Consideration of tungsten carbide rock bits includes looking at bit materials [ ] as well as bit operation and maintenance. Two basic tungsten carbide rock hits are the button bit and the four-wing carbide insert bit. Three common hit-to-drill-steel connections are the bottom drive, tapered drive, and shoulder drive. Bottom drive bits arc typically used for singlepass or longhole drilling, with all percussion drills from handheld sinkers to heavy track drills. Tapered socket bits are available with shallow or deep carhide inserts, for the lowest cost depending on the rock type being drilled. Shoulder drive bits are available in all-steel or carbide insert design.

Jan 12, 1981

By R. H. Murray

The Kamyr countercurrent tower leach process consists of a true countercurrent leach ?with a flocculated ore and fibre mixture entering the top of the tower and a cyanide solution or alternative lixiviant as well as a barren wash solution entering the bottom of the tower. It offers the possibility of including the entire leaching, solid-liquid separation and clarification processes into one unit or tower as opposed to the multiple leach tanks, filtration and clarification sections required in a conventional leach and precipitation plant. The tower process has been demonstrated in the laboratory and found to be effective for leaching gold, silver and other amenable ores. Based on laboratory results, Gencor and Kamyr have jointly constructed a 200 ton per day pilot plant in order to prove the process on a larger semi-production plant scale.

Jan 1, 1989

By Michael Prince

"Managing slurry is a constant challenge for mining operations. Since slurries are not uniform, the challenge is complicated by varying rheology, velocity, temperature and pressure, all of which affect how the slurry moves through the pipeline and how destructive it is to the system it is flowing through. Picking the right equipment from the outset — the right size pipe, the right size pump and the proper valves for the application — allows mines to operate more efficiently. Better valve designs deliver multiple benefits — they can lower the cost of operations, reduce the amount of maintenance and associated downtime required and are better for the environment. Historically, modulating systems have used ball, plug and pinch valves to manage the flow of slurry, but each of these alternatives has limitations. Ball valves require ceramic lining in order to delay wear, and once a ball valve does wear, the entire valve must be replaced. Similarly, plugs in plug valves should be coated to perform in control systems, and whole valves must be swapped out upon wear. Pinch valves are expensive and only require replacement of the sleeve. However, sleeve replacement involves an extremely arduous process in which the valve is completely taken apart.Traditionally, designers have avoided using knife gate valves (KGV) in modulating systems because KGVs have not been able to hold up under the harsh operating conditions. The throttling that is required in some of these processes rapidly fatigues conventional KGVs, rendering them useless and in need of replacement. Fortunately, innovative design changes have the potential to change established views.Breaking new groundRecognizing the need for improved components, Victaulic took on the challenge of designing a valve that could withstand abrasive slurry systems for a much longer period of time. The first step in this process was to talk to miners, maintenance personnel, process engineers and operators in the field about the limitations of current offerings and then determine design specifications for an ideal replacement.Many of the responses to these inquiries were very similar and reflected challenges with current operations; the primary objective was to find a valve that would be lighter and cheaper than the valves currently in use. In theory, a lighter valve would be easier to replace, and since replacements need to be performed frequently, a cheaper valve seemed like the right idea."

Feb 1, 2019

By Russell L. Wood

Introduction It is the morning after and there is one monumental hangover among many, if not most, of the oil companies that invested in mining in the past decade. How an oil company looks at mining depends on the time period. A few years back, around the time of investment, they were probably looking at a balance sheet of their own that was beginning to go wild. Many of their commodity prices already increased two-, three-, or fourfold, with no end in sight. There was a need to invest their earnings someplace before the stockholders or the government got too interested. And that someplace needed to be an industry where their own management skills could be applied. In mining there was an industry amazingly similar to their own. Both worked with nonrenewable natural resources, dealt with the same types of government agencies, and had the same type of critics and pressures from the general population. Oil executives saw mining as an industry that was somewhat backward as compared with their own. They also saw how a generous ration of the capital and management skills, so handsomely bestowed upon the oil industry, could be used to great advantage. But, looking at mining through the eyes of an oil company today, this is what might be seen: • An industry that has been spectacularly unprofitable for the past few years; • An industry of many commodities, any of which can go bad on short notice for protracted periods, for a variety of unpredictable and uncontrollable reasons, or for no reason at all; • A labor-intensive industry, often beset by labor problems. And with only limited potential for further economic mechanization or automation in today's primitive mining environment; • An industry confronted with external, foreign, and political problems, with no reasonable expectation of near-term relief; and • An industry that does not appear to have many "up" periods in its immediate future. And, there is little chance for either big, fast bucks or long periods of large, steady earnings. What Went Wrong? The visions of a few years back seemed as correct then as today's viewpoints seem to be now. What happened to change these views? What went wrong? The simplest and easiest answer is that if the economy was normal back then, nothing would have gone wrong. This is an easy answer but, unfortunately, probably incorrect. Let us take a broad overview. Certain events enabled and prompted oil companies to invest heavily in mining. These same events were major factors in precipitating the worldwide recession that has grievously injured mining and has brought those mining investments into disrepute. Taking a somewhat narrower, but still broad overview, the simi-

Jan 3, 1985

By T. R. Ellis

"Editor’s Note: This is an expanded abstract. The full report is available on SME’s website at http://www.smenet.org/publications-resources/ resources/sme-valuation-standards-tutorials.The author has three goals for this review of mineral valuation standards internationally.1. To place the SME Standards and Guidelines for Valuation of Mineral Properties (SME Valuation Standards) and International Mineral Property Valuation Standards template (IMVAL Template) within the global context of existing mineral valuation standards.2. To review the current status of harmonization of each International Mineral Valuation Committee (IMVAL) member’s mineral valuation standards (or code) with the IMVAL template and suggest remedies for issues found.3. To suggest future enhancements for the IMVAL Template and SME Valuation Standards, and to suggest future roles for the IMVAL and SME committees. From the author’s review, Ellis draws the following conclusions.The SME Valuation Standards comprise a minimum set of principles-based standards and guidelines for developing and reporting valuations of mineral properties (including petroleum properties) for public and private use, subject to jurisdictional requirements. The standards are also designed to provide mineral valuation guidance that supplements application of the International Valuation Standards Council’s International Valuation Standards (IVS) and the U.S. government endorsed Uniform Standards of Professional Appraisal Practice (USPAP), published by the Appraisal Foundation.The SME Valuation Standards is the first set of valuation standards developed by a minerals institute adopting and modifying the IMVAL template. As a result, the SME standards are essentially totally harmonized and otherwise aligned with the IMVAL template. IMVAL was initially conceived in 2012 as a discussion body to aid harmonization of each member’s valuation standards, by modifying to function the same. IMVAL primarily developed the IMVAL template, published in July 2016, to produce an agreed reference framework of essential mineral valuation guidance content as the goal for harmonization of the Australasian Code for Public Reporting of Technical Assessments and Valuations of Mineral Assets (VALMIN Code), The South African Code for the Reporting of Mineral Asset Valuation (SAMVAL) and the Canadian Standards and Guidelines for Valuation of Mineral Properties (CIMVal standards and guidelines). The harmonization would result from each mineral valuation standards committee modifying its standards to operate similarly to the IMVAL template, producing valuation reports with similar content and value for the same mineral property. The template is also available for other bodies to adopt and modify for their regional setting’s needs, as SME did, or use as a convergence goal when updating an existing standard."

Jan 2, 2018