Search Documents

By T. A. Rundle, K. Kim, W. M. McCabe, E. C. Gregory

Overcoring tests were conducted at the Near-Surface Test Facility(NSTF) to assess the suitability of five techniques (U.S. Bureau of Mines borehole deformation gauge (BDG), Commonwealth Scientific and Industrial Research Organization (CSIRO) hollow inclusion stress cell, Luleå triaxial gauge (LuH gauge), and Council for Scientific and Industrial Research (CSIR) doorstopper) for in situ stress determination in a closely jointed basalt. This effort is in support of the Basalt Waste Isolation Project, which is studying the feasibility of locating a nuclear waste repository in the basalts of the Hanford Site in southeastern Washington. This paper presents the results from the overcoring study that formed the basis for selection of two techniques to be used during the further exploration of the basalt formations at depth.

Jan 1, 1983

By H. Lyn Bourne

This is the fifth annual tabulation of mineral royalty information. This tabulation, like the previous editions, includes all of the earlier data. There are also 60 new entries. In addition to royalty information, some entries show the cost of purchased reserves. Two articles relative to the evaluation of minerals reserves appeared in December, 1986. R.H. Paschall (In the Aggregate, ME, p 1139) wrote a good article, although it lacked specific royalty data. However, this author takes exception to two ideas in Paschall's column. Paschall contends that the royalty rate does not affect the mineral appraisal. This present author could not disagree more. Paschall also claims the location of an industrial mineral deposit is the only serious or practical caveat in comparing royalties. Comments received here from readers helped make the list of caveats that are cited each year. The readers will decide which factors influence the mineral value for their commodities of interest. Paschall's point about the relationship of the parties who are negotiating a royalty agreement is important and very well taken. The other article, written by William Vernon (Pit and Quarry, December 1986), gives a step-by-step process on how to conduct a mineral appraisal. The article cites three reasons for an appraisal: transfer rights; collateral for a loan; and taxation. A fourth reason is to establish adequate compensation for reserves lost through condemnation. This author has appeared in several court cases where compensation for loss of mineral reserves through condemnation required a mineral appraisal. Royalty rate becomes an important factor in the appraisal process, although the Pit and Quarry article refers to that part of the valuation equation as "profitability." Both articles were well written and are recommended reading for those interested in mineral valuations. The same caveats that have appeared in previous columns relative to factors that influence the value of reserves are restated. The data in the table serve as a general reference and are not intended to present an absolute scale of reserves costs. Several factors influence the value of any mineral commodity. The factors include: • location/transportation - especially significant for most industrial minerals; • market conditions both for the commodity and the company acquiring the right to mine; • quality or grade of the deposit as it reflects the amount of processing/beneficiation necessary to produce the finished product; and • legislative restrictions and conditions for mining a given material at a given site. These and other factors will significantly influence the cost of reserves. The table shows the range of royalties and the variations in the basis of computing the fees. In a few instances, it gives the cost of acquired reserves based on purchase price and quantitative estimates of the material in place. The table lists the commodity in column 1, and the subsequent columns give: • the location by state, US geographic area, or Canadian province ; • the cost - R for royalty and P for purchased cost; • the year in which the lease or purchase agreement occurred; and • comments or footnotes for more information. The cost column requires more explanation. The units may refer to cubic yards (/cu yd), cubic feet (/cu ft), short tons (/T), or acres (/A). 1 cu yd = 0.76 M2 1cuft = 0.28m3 1 st = 0.9072 t 1 acre - 0.4047 ha or m2

Jan 7, 1987

By L. F. Ruppert, P. A. Freeman, R. C. Milici, S. J. Tewalt, L. J. Bragg

The U.S. Geological Survey has completed a dig-ital coal resource assessment of six of the top-producing coal beds and coal zones in the northern and central Appalachian Basin coal regions. These include the Pennsylvanian-aged Pittsburgh, Upper Freeport, Lower Kittanning, Fire Clay, Pond Creek, and Pocahontas No. 3 coal beds and coal zones. Resources were calculated on all of the coalbeds/zones, with the exception of the Lower Kittanning coal bed. Preliminary original resources are estimated at about 93 billion short tons (84 billion tonnes), of which about 66 billion short tons (60billion tonnes) remain. Much of the remaining coal in all five coal beds/zones is thinner [<3.5 ft (1.07m)] and deeper [>1,000 ft (305 m)] than the coal that has been mined, but economic resources are still available and mining in each coal bed/zones will continue throughout this decade and into the next given current market conditions.

Jan 1, 2001

By G. Lawrence, R. Pieters, A. Leung, T. Pedersen

The Main Zone and Waterline pit lakes at the Equity Silver Mine near Houston, BC (Canada) are the sites of a new 3-yr research program with three primary goals: 1) understanding controls on metal concentrations in the lakes; 2) using mesocosms to test a variety of remediation strategies; and 3) verifying and improving an existing coupled physical-geochemical model with the goal of improving predictions of pit lake water quality. Initial data from two summer surveys in the Main Zone pit lake reveal elevated dissolved metal concentrations (e.g. [Zn] as high as 800 µg/L) present in a two-meter-deep mixed layer, and elevated particulate metal concentrations towards the bottom of the water column. Hydroxide sludge, a byproduct of ARD treatment, is being discharged to the surface waters of the Main Zone pit lake. The sludge sinks rapidly to the lake bottom, leading to deep waters with elevated levels of dissolved O2 and total metals. By contrast, the deep waters of the proximal Waterline pit lake are mildly reducing, manifested by depletion of O2 and elevated levels of dissolved Fe. These reducing conditions have led to elevated levels of As (up to 1500 µg/L) in Waterline pit deep waters. The contrasting behavior of these two pit lakes, as well as the processes controlling metal concentrations in the lakes, will be discussed.

Jan 1, 2002

By D. Kruse

Top down constructed large diameter (up to 90 m [300 ft]) shaft design and constructability issues present an interesting suite of challenges and opportunities highlighted in this paper. The study covers 2D and 3D finite element models used to: analyze various failure modes, evaluate the shaft liner and internal structures? response to seismic loading, assist in segment design, and assess final structural design tradeoffs. Efforts to achieve economic advantage over conventional heavy civil practices have prompted innovative solutions for ring and segment design, ring build assembly, and annulus backfill grouting. Intended for soft ground conditions, relationships between soil parameters and structure design are also explored.

Jan 1, 2011

Traditional loading systems have relied for many years on wheel and track loaders, power shovels, conveyor belts, and more recently, hydraulic front shovels. Each has certain advantages and disadvantages, depending largely on job conditions. Hydraulic backhoes were introduced several years ago as still another truck loading option. At first, buckets were small and backhoe use was limited to small earthmoving projects. Now, as backhoes are equipped with shorter sticks and bigger buckets to move larger quantities of earth. The "mass excavation" concept offers an excellent truck loading option in many situations. System Development and Advantages Mass excavation was first used successfully by contractors in site development and highway construction, loading both on-highway and off-highway trucks. Operators were able to take advantage of the excavator&apos;s ability to work in poor underfoot conditions and dig in tough materials. The technique was first applied to mining in the kaolin mines of central Georgia. Kaolin, one of the world&apos;s most abundant minerals, is used to make paper, paint, ceramics, rubber, plastics, and many other products. Since kaolin clay is slippery when wet, load-out with wheel loaders is very inefficient. Also, kaolin is found in very spotty deposits due to the weathering process involved in its formation. Consequently, draglines are also impractical for kaolin mining since they don&apos;t have the mobility to move between clay deposits. In response to these mining conditions and kaolin characteristics, mines began using excavators in mass excavation as early as 1976. They have developed a system that takes advantage of the excavator&apos;s •high penetration and breakout force in tight materials; •fast-cycling hydraulics; •ability to work in poor underfoot conditions; and •mobility in comparison to draglines. This loading method has been successful in Georgia&apos;s kaolin mines and now can be applied to other mining operations as well. The excavator&apos;s ability to carefully dig spotty ore deposits is an asset at uranium mining operations. Any mine can take ad-

Jan 3, 1982

By M. S. Safarzadeh

Over the last fifty years, the treatment of enargite concentrates has not received much attention primarily because of the availability of other clean concentrates suitable for processing with existing smelting and/or leaching technologies. As traditional copper ores have become scarcer, copper-arsenic ore deposits have garnered more interest. Arsenic release is a significant concern during the treatment of enargite by pyro or hydrometallurgical methods. Enargite is also very refractive in standard leaching procedures. Thus, economical treatment options for enargite concentrates are needed. Preliminary experiments have shown that the acid-bake leach process could be adapted and used for the treatment of enargite concentrates. In this study, low-temperature (100-400 ºC) sulfuric acid baking of an enargite concentrate followed by water-leaching has been evaluated. The results indicate the thermal transformation of enargite to copper sulfate during sulfuric acid baking, with most of the arsenic being released from the concentrate into the gas phase for baking at 400 ºC. The condition for maximum copper extraction (~100%) from the concentrate was found to be 400 ºC, sulfuric acid amount of 0.5 mL/g of concentrate, and 2 h baking time. Part of the arsenic was captured in the form of arsenopyrite (FeAsS). XRD analysis proved the presence of some arsenic in the form of claudetite (As2O3) in the baked concentrate. Acid baking of pure enargite behaved in similar fashion.

Jan 1, 2012

By P. R. Clifford

Phosphogypsum is a byproduct of the manufacture phosphoric acid. There are approximately one billion tons of phosphogypsum stored in stacks in northern and central Florida. The Florida Institute of Phosphate Research (FIPR) is investigating potential uses of phosphogypsum. These include using phosphogypsum as a road base material, as a soil amendment in agriculture, as a daily cover in landfills, and as a construction material. The results of this research will be presented and will be discussed in light of regulatory barriers to the use of phosphogypsum.

Jan 1, 2002

By S. Afrouz, C. Keles, W. R. Reed, E. Sarver, T. Akinseye, A. Greth, L. Pan, F. Animah

Among underground coal miners, roof bolter operators are generally considered to have some of the highest risks for hazardous respirable dust exposure. This is because bolting requires drilling into roof strata that can often be a source of silica and silicate dust, which are associated with occupational lung diseases. However, little is known about the variability of dust characteristics (e.g., mineralogy constituents, particle size) in the vicinity of the bolter—or when specific dust controls are applied. As part of a prior NIOSH study, respirable dust samples were collected during several different events in standardized locations around an active roof bolter, and personal samples were also collected from the operator during the cleanout of the bolter’s dust collection system when it was equipped with a novel wet dust box versus a traditional dry box. Those samples were made available for follow-up analysis by scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM–EDX), as well as direct-on-filter Fourier transform infrared spectroscopy (FTIR). Results showed variability in dust constituents and particle sizes at locations around the roof bolter, and indicated some event-to-event differences in dust sources. Additionally, compared to the dry dust box, the wet dust box appeared to reduce (by 41–82%) the relative silica and silicate content in the respirable dust to which the operator was exposed during cleanout. Furthermore, an inter-laboratory comparison demonstrated the reproducibility of a standardized direct-on-filter FTIR method for estimating quartz mass (i.e., the predominant form of crystalline silica) in respirable coal mine dust samples. However, for constituent analysis by SEM–EDX, differences observed between results from two independent labs indicate that standardization of the analytical protocol is necessary to enable comparability of results.

Jan 5, 2024

By D. P. Richards

Tunneling in carbonate sedimentary rocks such as lime stones and dolomites can be difficult when solution channels or voids are anticipated. Addressing the risk aspects associated with these formations can be done effectively through the Geotechnical Baseline Report (GBR) by properly characterizing the ground and ensuring that the Owner?s and the Contractor?s interests are represented and protected. This paper presents a review of tunneling difficulties in these rocks and includes a review of site investigations, geologic characterization, and presentation in the GBR. Key construction issues are also discussed, including appropriate excavation technology, mechanisms of face support and groundwater control, and quantifying grout takes.

By Drupad B. Desai, Bruce Chang, Jay L. Merritt

This paper reviews difficult ground conditions encountered along the alignment of large-diameter sewage tunnels for the City of Los Angeles. It offers a detailed one-of-a-kind solution to a unique problem for shallow urban underground tunnels in a seismic zone, using state-of-the-art materials, technology, and equipment. The following topics are discussed in detail: • Geotechnical Design consideration for tunnel traversing through an active fault zone. • Seismologist evaluation of possible fault-offset problems where a fault zone crosses the alignment, in the event of an earthquake of moment-magnitude 6.5. • Probability analysis regarding "recurrence interval." • Structural design of tunnel subjected to displacement, subjected to axial elongation or shortening, and capable of rotational freedom. • Special joint details.

Jan 1, 1989

By L. Bergkvist

"History can provide many answers with regard to what today’s mining industry looks like and how we got to where we are today. It has always been self-evident that safety has to be given the highest priority and, throughout history, many mine workers have been injured, become ill and have even sacrificed their lives due to the way in which attempts have been made to extract the ore, often due to ignorance of the dangers being faced. In more recent stages of history we have seen certain dangers being compensated by means of higher wages and bonus systems in order to have the work carried out: one example of this is when the rock heating method was employed and the men who first went underground to put out the fires that were burning, were paid extra. The working conditions, to which these people were exposed, with smoke-filled closed spaces, shortened their life expectancy considerably and today we can ask ourselves whether it is really possible to value these efforts just by higher wages. In all mines worldwide the working environment has been improved and many mining companies have a zero vision where work-related injuries and accidents are concerned. Despite this, incidents of varying severity still occur and a continuous improvement process and ongoing training is necessary in order to constantly minimise risks and improve the working environment. Atlas Copco takes this into account in all its development and we not only review our own production units but also the needs of our customers, with regard to the machinery that is produced in order to cater for customers’ safety and production objectives. Underground mining probably started at the beginning of the 11th century when people with modest tools tried to extract ores that were present in the bedrock. Methodology has developed enormously over the years with a strong focus on increased efficiency and higher production. In different parts of the world the development is driven forwards at different rates depending on which controlling factors are regarded as necessary. Political decisions, profit goals and productivity have partly controlled the development, but the greatest factor where improvement is concerned still remains with increased understanding of the totality. During more than 1000 years since underground mining has been conducted, all individuals at all levels have constantly improved their expertise and the human element has been of great importance with regard to the development that has been made, even though technology often occupies a leading role when we describe the improvements made."

Jan 1, 2011

By Mohammad R. Jafari

The Camp Dresser & McKee (CDM) has been retained by the Sacramento Regional County Sanitation District (SRCSD) to design the Mather Interceptor, a portion of the South Interceptor and Mather Interceptor program. The Mather Interceptor consists of 14,667 feet of 54 to 72 inch gravity interceptor. Approximately 90 percent of the alignment will be constructed via tunneling. Cobbles and boulders in a sand/gravel matrix dominate the ground conditions combined with seasonal perched groundwater table at some of the deeper reaches of the alignment, impacting design consideration. This paper will present the results of a comprehensive geotechnical investigation conducted for this project and in-depth technical evaluation of various trenchless techniques feasible for tunneling in the cobble and boulder laden formations of this project. This paper will also present the risks and issues of the design alternatives and selection criteria.

More than 410,000 visitors from 171 countries helped bauma ’04 set new attendance records at the world’s largest construction machinery and mining technology show. The show, held in Munich, Germany March 29-April 4, marked bauma’s 50th anniversary. At the last bauma show in 2001, attendance was about 406,000 people from 157 countries. At bauma ’04, international attendance increased to 31 percent from 27 percent in 2001. In addition to record-setting attendance, bauma ’04also attracted 2,801 exhibitors, up from 2,341 in 2001. Exhibitors came from the United States, Europe, China, Japan and the Middle East. Exhibitor space topped 500,000m2 (5.4 million sq ft), another record. And, for the first time, there were more foreign exhibitors than German exhibitors, show organizers said.

Jan 1, 2004

By C. P. Kelley, T. J. McKeon

Several recent developments in fine screening technology have been implemented at the DuPont Starke, Florida plant allowing enhanced zircon recoveries while minimizing operator requirements and total operational costs. The total design concept came about through the efforts of engineers at Derrick Corporation (Buffalo, New York), DuPont Titanium Technologies (Starke, Florida) and Roche Mining (Carrara, Australia). The use of the Kelsey Jigs for zircon recoveries from the tailings stream requires two wet sizing functions in order to operate properly. The first wet sizing is required on the initial mineral slurry feed to the Kelsey Jig. This sizing is intended to protect the Kelsey Jigs internal screen basket from plugging with nearsize particles, thereby keeping production rates maximized. The second sizing function is intended to recover properly sized garnet ragging material, which inadvertently ends up in the tailings stream leaving the Kelsey Jig. The unique machine design developed by the three partners in this project incorporated both wet sizing functions (protection and garnet recovery) into a single patented high capacity wet screening machine fitted with patented screen surface technology. This screen surface technology allowed for high capacity slurry handling capabilities at separations as fine as 230 microns while experiencing no nearsize blinding and extremely long screen panel life. The high open area urethane screen surfaces utilized in the application typically last 20 to 30 times longer than stainless steel wire surfaces. The stacked machine design minimized total equipment requirements and screen footprint requirements, and reduced power consumption and overall installation costs.

Jan 1, 2005

By Ben Hayes, Michael Ryjevski

The Palm Jumeirah is the smallest of the three Palm Islands (Palm Jumeirah, Palm Jebel Ali and Palm Deira). It is located on the Jumeirah coastal area of the emirate of Dubai, in the United Arab Emirates (UAE). The unique man made island is built in the shape of a date palm tree and consists of a trunk, a crown, 17 fronds and a surrounding crescent island that will form a breakwater. The Jumeirah Palm Island is primarily are treat and residential area for living, relaxation, and leisure. It will contain themed boutique hotels, three types of villas, shoreline apartment buildings, beaches, marinas, restaurants, cafes and a variety of retail outlets.

Jan 1, 2007

By W. Collingwood

As open pit mines continue to grow deeper and productivity continues to increase, the management of respirable dust and noxious gases can become a challenge. The natural wind flow in open pit mines is often recirculatory. This recirculation traps dust and gases in deep open pit mines. This problem is particularly acute in high latitude open pit mines due to a phenomenon known as an atmospheric inversion. In the winter, arctic and subarctic regions experience short days and long nights. This deficit of solar radiation creates a situation in which cold, still air accumulates near the bottom of the pit. In open pit mines, this can result in unhealthy accumulations of gases and other contaminants in the open pit mines. In this study, the natural wind flow patterns in and around open pit mines were investigated using a computational fluid dynamics (CFD) program. Two dimensional models were created for a variety of pit geometries. The effect of depth, slope angle, and wind speed on the recirculation pattern in the pit was examined.

Jan 1, 2011

By Anthony Leddin, Gillian Dooley

This paper is concerned with mineral policy in Ireland and how it might be improved to encourage more exploration and investment in mining in the country. The approach is to first outline the main desirable characteristics of a comprehensive national mineral policy document. This aspirational document is then used to assess the current regulatory, legislative and fiscal frameworks for mining in Ireland. The analysis also contains a brief account of the history, structure and characteristics of the mining industry in Ireland. The main focus of the paper is to identify those aspects of the existing framework that erode Ireland’s attractiveness to mineral investment and to suggest policy improvements.

Jan 1, 2005

By Lane White

Refractory gold ores are those from which a significant percentage of the gold cannot be recovered by conventional cyanidation. Historically, roasting has been the primary method for rendering such ores amenable to gold extraction; however, roasting creates environmental problems that are not acceptable in many locations. During the 1980s, consistently strong gold prices drew increasing attention to refractory gold ores, and new processing schemes were commercialized, most prominently aqueous pressure oxidation and more recently bacterial oxidation. Since 1985, pressure oxidation has been incorporated into four plants processing refractory gold ores. A fifth plant is scheduled for start-up in early 1990, and three additional plants are scheduled for production before late 1992. A technical session on treatment of refractory ores was included in the program of `World Gold &apos;89, a Gold Forum on Technology and Practices&apos; held by SME and the AusIMM in Reno, NV, Nov. 5-8, 1989. This article summarizes material from five of the papers presented during the refractory gold session and published in the proceedings of `World Gold &apos;89,&apos; edited by Roshan Bhappu and Rod Harden. The complete proceedings are available from SME Publications Sales, P.O. Box 625002, Littleton, CO 80162-5002 $53.50 for members, $38.50 for student members, and $73.50 list price.

Jan 1, 1990

By A. Anani

The need to optimize surface mining operations has led to the use of discrete event simulation (DES) modeling of truck-shovel systems. Often, these models assume truck cycle times are independent and identically distributed (iid) random variables, although, with significant bunching on the haul routes, this may not be valid. The objective of this paper is to present a methodology to (i) account for truck bunching due to slow trucks; and (ii) test for cycle time dependence (i.e. whether truck cycle time data is iid or not). We built a DES model that accounts for bunching due to a slow truck(s) and used the cycle times as data for further analysis. We then tested for cycle time dependence using Pearson correlation coefficients. The results show significant correlation of truck cycle times for different number slow trucks, with variable speeds. Assuming iid in modeling results in over-estimation of productivity and the uncertainty surrounding it. The over-estimation of uncertainty is pronounced when the relative difference in truck speed increases. The confidence interval of the means of truck loads/shift decreases with increasing number of slow operators. This work extends the usefulness of DES in truck-shovel applications.

Feb 27, 2013