Search Documents

By Kelvin K. Wu

A coal waste disposal dam failed on Buffalo Creek near Saunders, West Virginia, on February 26, 1972. This accident resulted in the loss of 125 lives, left over 4000 people homeless, and resulted in millions of dollars in damage to several downstream communities. As a result of this tragic event, major changes occurred in the mine waste disposal practices used by the U.S. coal industry. This paper summarizes changes in U.S. coal-waste disposal practices in the nearly 35 years since the Buffalo Creek dam failure and identifies safety issues that need to be addressed for continued improvement. While many organizations and individuals have played roles in the improvements that have occurred, this paper focuses on the role played by MSHA and its predecessor agencies.

Jan 1, 2006

By Paul Kunze

When a new bridge was needed across the upper reaches of the Yellowstone River in Montana, removing the old concrete bridge piers became an environmental concern for the highway department engineers. The location is about fifty miles downstream from the north edge of Yellowstone Park. The determination was made by the federal and state agencies charged with protecting the resource, that the old piers had to go but the river bed had to remain unchanged. Concerns were expressed that removing the concrete presented the potential for environmental damage to this protected portion of the river. These concerns prompted the state to place stringent restrictions on the contractor in the way they carried out the demolition and disposal of the piers. The reinforced concrete masses had to be removed to an elevation at least fifteen feet below the river bed and every bit of concrete debris had to be removed from the river channel. Explosive removal was discouraged, but the only other options: saw cutting, mechanical or chemical breaking, were not viable.

Jan 1, 2014

By Peter White

A bridge reconstruction project involved driving pipe piles for the new foundations. Disturbances within soil layers at depth caused sinkholes to open up within the construction site. After a near fatal accident, the pile driving installations were suspended. The solution involved ground im­provement through cement grouting with sleeve pipes and special grout additives to minimize migration of cement grout.

Jan 1, 1997

Keywords: Pyrometallurgy, zinc, electrowinning Zincor has been producing zinc since 1969 via the roast-leach-electrowinning process. It is the only primary zinc producer in South Africa, and currently supplies the entire country with zinc. The plant was built by Goldfields of South Africa, on the site of an old gold and uranium mine. Since then, the ownership of the plant has changed a couple of times, and the plant and process have also been improved. Production output has increased from around 80 000 tons per year to more than 110 000 tons per year. This was done mainly through increasing the capacity of the roasters and acid plant. Zincor produces four main grades of zinc: SHG, Zn1, Zn2, and Zn4, in three shapes: a 25 kg ingot and 1 and 2 ton jumbos. In 2005, a pre-alloy furnace was built that enabled the production of jumbos pre-alloyed with aluminium. This has allowed Zincor's customers to improve the efficiency of their continuous galvanizing lines and to lower their production costs.

Jan 1, 2006

Green policies have gained momentum since the 1972 Stockholm, Environment Conference. The environmental movement has influenced political initiatives both in New Zealand and abroad. Governments and international institutions have addressed local, regional and global environmental issues with varying degrees of success. New Zealand so far has not supported the United Nations' call for sustainable development in a consistent manner. New institutions and new rules for resource management mean there are opportunities to look after the land in different and more ecologically sensitive ways than has happened in the past. The increasing influence of regional councils in resource management planning will have important implications for mining and mineral exploration. These trends are discussed and possible future events outlined. Green policies have gained momentum since the 1972 Stockholm Environment Conference. Environmental issues are now global and the twentieth year Environment Conference planned for 1992 is likely to see new commitments made by world leaders and their national governments. Green politics may be the popular trend of the moment but green principles of managing the earth's resources are here to stay. There are many businessmen, many technologists, and many politicians who have hoped that the environmental movement was a passing fad and would fade into oblivion. The evidence is otherwise. Far from passing into oblivion, the environmental movement is growing rapidly. Each year brings further scientific data that indicates mankind is on a self destructive course unless we learn how to better manage the earth's natural resources. This information has contributed to a growing population of environmentally aware people. In the last 20 years there have been messages of concern about a population increase out of control and the energy crisis which focused on dwindling oil stocks. The issues are all interrelated including the present global issues of climate change and thinning ozone layers. The attention being given the messages by the United Nations and member states requires similar attention by industry. The problems have been identified; the challenge is to determine what should be done about them. Every challenge brings new opportunities and the future need not be doom and destruction. Mining is seen by some of the environmental action groups as unnecessarily destructive of the environment, but I do not see mining ceasing in the next few decades. Rather, the rules will be clearer with some areas excluded from mining, the methods of extraction will improve, the technology of processing will become more sophisticated and restoration of mining sites will be not only normal practice worldwide, but the end result may leave no hazards, may enhance the landscape and may result in acceptance of the industry by the general public. For that to happen, commitment and cooperation is required between the industry, the government, and society. As an Officer of Parliament my role is to review the system of agencies and processes established by Government for allocating, using and preserving natural resources and to report whether the system is maintaining and improving the quality of the environment. I also have a responsibility to see that the environmental planning and management carried out by public authorities is effective. That Ineans I have a keen interest in how the mining industry is administered by New Zealand public authorities, including Ministers of the Crown and district and regional councils. Today I intend to review the approach to resource management being taken by international agencies and by the New Zealand Government, and to comment on how environmental impact assessment for mineral exploration, as well as mining, may be administered in the future.

Jan 1, 1990

Rb-Sr measurements on total-rock samples of granitic rocks from the Mount Isa region have confirmed the existence of two periods of granite-forming activity. The Kalkadoon Granite, together with the Ewen Granite and possibly an older phase of the Sybella Granite, has been shown to belong to the earlier age-group at 1760 m.y.; the Wimberu Granite and a pegmatite associated with the Sybella Granite have been dated at 1540 m.y. The initial Sr ratio suggests that the Wimberu Granite may be new material of deep-seated origin.Further Rb-Sr measurements have confirmed previously-reported K-Ar results upon biotites from these rocks, whilst showing that, in this metamorphic terrain, biotites have lost varying amounts of radiogenic Sr and Ar, and therefore yield ages which are younger than the true age of the second event.

Jan 1, 1966

By Woodcock J. T, Jackson N

Wattle Gully Gold Mines N.L. of Chewton, Victoria, has decided to replace its present battery plant by a new mill to treat a free milling gold ore, after fine grinding, by concentrating coarse gold in a jig concentrate for amalgamation, and fine free gold and auriferous sulphides in a flotation concentrate for cyanidation. This paper outlines the economic justification and advantages of this step. In a review of the present position at the mine, a history of the company is followed by a description of the ore and its occurrence.Present treatment practice in two separate battery plants is described. Treatment tailings assay 1 dwt/ton gold and a substantial part of this gold is finer than 200 mesh.Experimental work showing how recovery may be improved is discussed and alternative methods of concentrating coarse gold mentioned. It is decided that the most suitable method for recovering gold from the ore is by jig concentration plus flotation.The merits of various flowsheets incorporating these techniques in the existing plant and in a new plant are assessed. It is concluded that there is no advantage in extending or converting the existing two battery plants, and it would be more economical and satisfactory to build a new plant.An economic study shows that for a capital expenditure of £120,000 a new plant could be erected to treat 70,000 tons p.a., working a 5-day week, and return an additional 14.2/- per ton, or £50,000 p.a., in revenue over the existing plant. It is estimated the plant cost can therefore be recouped out of savings inside three years. Probable ore reserves are sufficient to cover this period and additional ore will certainly be developed.INTRODUCTIQNSince 1934, Wattle Gully Gold Mines N.L. has been mining a lode gold ore at Chewton, near Castleniaine, and treating it by stamp milling and plate amalgamation, plus table concentration of auriferous sulphides. In 1954, following two years of unprofitable operation, a rehabilitation programme of all sections of the mine and plant was commenced. In the treatment section, two, major prospects for improvement...

Jan 1, 1959

In 1950, about a third of the world?s population lived in cities. That figure has steadily risen throughout the following decades. Now it is believed that about 60 percent of the estimated 8.1 billion people in 2030 will be living in urban areas. The strain on infrastructure in cities in the developed world is already showing. And the rapid growth in developing nations today is adding to the shortage of materials, equipment and labor needed to keep up with this growth. So, while materials and labor may be in short supply, there is no shortage of work for the underground tunneling and space industry. In June, 718 of those professionals from around the world were in San Francisco, CA for the North American Tunneling (NAT) conference, put on by the Underground Construction Association (UCA) of SME. The attendees spent the three days of technical sessions listening to international authors discuss the state of the industry, new technologies that have become available and updates on major tunneling projects throughout the world. The accompanying exhibit attracted 79 vendors, who displayed the latest in tunneling and underground space equipment and services. In addition to the technical sessions and the exhibit, the NAT featured three short courses ? ?DRB Process Update Workshop,? ?Soft Ground Tunneling Technologies? and ?Underground Blasting Technology and Risk Management.? And the post-meeting field trip to the Devils Slide tunneling project near San Francisco was sold out.

Jan 1, 2008

By Neal Lee, Braden T. Lusk, Jhon Silva-Castro, Patrick J. Jenks

"Timing and charge sequence are very important for optimized blast design. Traditional nonelectricinitiation systems have moved the industry toward a system of delays consisting of hole-to-hole androw-to-row timing sequences that mimic the application of nonelectric surface delays or dual delayinitiator systems that have been prevalent in the blasting industry for many years. The increasedutilization of electronic detonators allows for the use of Regular Rhythmic Timing (RRT) utilizing onlyone delay between charges and a selected charge firing sequence. The hole to hole and row to row (HHRR) timing method has been utilized for blasting optimization and allows for simplistic changes to the tie in phase of the blasting sequence. When using this traditional timing methodology, for some specific cases related to the number holes and rows, crowding occurs in the delay between charges with subsequent increase in the peak particle velocity (PPV) produced by the blast. This is in contrast to RRT where the timing between the delays remains constant."

Jan 1, 2016

Author's Note: Since the paper on "All-Flotation at North Broken Hill Limited" was read and discussed, the metallurgical results obtained have conclusively justified the adoption of the All-Flotation treatment.At present the shipping grades of lead concentrate produced from North mine ore range between 74% and 75% Pb, carrying approximately 43 oz. Ag and 4.5%-5% Zn. The lead recovery in lead concentrate is recording 95%-96% of the lead content of crude ore, and the milling and treatment cost on 6400 tons crude ore perweek of 96 hours has dropped to 6s. 3.6d. per ton on ore. With an increased ore tonnage, and with a new mill, considerable further reduction in costs is certain.New flotation machines, with 30 in. vertical depth of overflow (instead of 42 in. depth), are now being tried for the secondary granular treatment, with advantageous results. The treatment to-day is practically the same as that outlined in the paper, excepting that additional concentrate is returned for retreatment in the existing units.(Signed) A. LOWRY.Mr. T. A. READ: The author states (page 356 of Proceedings, No. 79), "The sulphide ore itself was then comparatively coarsegrained, a fact which permitted ready concentration of the galena contents by means of jigs, tables, vanners, etc."

Jan 1, 1931

By John A. Kiefer

Ground fault and overcurrent protection criteria for coal mine a.c. distribution systems were examined under a Bureau of Mines funded investigation. The report begins with a literature review which discusses relaying topics including instrument transformers, ground-fault pickup methods, static relaying, and comparison of relaying techniques. A chapter on ground-fault relaying provides recommendations for maximum and minimum pickup levels as a function of maximum ground current and power system line-to-ground capacitance. Research in the area of phase overcurrent protection has resulted in a complete set of procedural recommendations for the selection and setting of overcurrent relays and current transformers, molded-case circuit breakers, and distribution system fuses in coal mine power systems. The final chapter, which discusses relay system maintenance, introduces a unique test set which was developed by KETRON and used to test the performance of relaying systems in coal mines.

Jan 1, 1980

By Mary E. Cocklan-Vendl

Regulatory processes associated with development of major mining operations in Alaska and British columbia were evaluated using specific case studies. Included were one hard rock mine in Alaska (Red Dog Mine), one hard rock mine In British Columbia (Snip Mine), and one offshore gold dredging project in Alaska (WestGold SIMA). Based on a comparison of the three case studies, it became clear that the primary incentives for cost effective permitting are: 1) early and continuing coordination of proposed project plans, designs and schedules with key regulatory agencies and local area residents and 2) development of a sufficient level of baseline information on air quality, water quality, wetlands, endangered species, fish and wildlife, and socia-cultural conditions to support the required permit application. The U.S. permitting process worked in much the same way as the Canadian permitting process. Disincentives of mine permitting include high initial costs for baseline data gathering. However, a relatively high early investment resulted in more efficient permit acquisition and reduced long-term monitoring requirements. A common problem Identified was the inadequate supply of trained agency personnel with the requisite technical and permitting experience. This sometimes resulted in poor decisions and unnecessary changes in project plans and schedules.

Jan 1, 1993

The theme of the 2012 North American Tunneling conference (NAT) was ?Tunneling: Driving Value.? This theme best reflects where the tunneling and underground construction industry is to-day. Major advances that have been made in technologies have provided tremendous improvements in productivity, which, in turn, have allowed the industry to deliver more cost-effective and less disruptive solutions to the nation?s infrastructure needs. Despite a weak economy, domestically and globally, cities and states continue to spend billions on infrastructure improvements. For the underground construction industry, that means more transportation and water, wastewater, storm water projects and other underground structures. And, for each project completed, underground construction and tunneling technology grows. The NAT conference, put on by the Underground Construction Association (UCA) of SME, provides an outlet for technology transfers among professionals. This year?s conference, held in Indianapolis, IN June 24-27, attracted 918 attendees, up from 803 at the last NAT in 2010. The accompanying exhibit also featured 116 exhibitors occupying 140 booths. That was up from 108 booths in 2010. So, the meeting continues to grow as underground construction professionals throughout the world seek to learn from their peers.

Jan 1, 2012

By J Elsen, R Snellings, K Van Balen

This research concerns the mineralogical study of the physico-chemical reactions taking place at the pozzolan-binder interface. Lime binder/ pozzolan mixtures have been prepared for different natural zeolites. Analcime, phillipsite, chabazite, erionite, mordenite and clinoptilolite were mixed with portlandite and water, after which the progress in the reaction was quantitatively determined by thermogravimetrical analyses from three to 180 days. A first and important step was the thorough characterisation of the raw materials by quantitative X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscope energy- dispersive X-ray (SEM-EDX) measurements of the zeolite minerals, Brunauer-Emmet-Teller (BET) specific surface area measurements, grain-size analyses and cation exchange capacity measurements. Beside these zeolite samples with varying Si/Al ratios, two clinoptilolite samples exchanged to the calcium, potassium and sodium form were studied and the difference in their short- and long-term reactivity was assessed. Also the difference in reactivity between identical clinoptilolite samples ground to different grain sizes, obviously having different specific surface areas, was determined experimentally. The results indicate that the external surface area only influences the short-term reactivity, whereas the cation content has effect on both long- and short-term. Na-exchanged samples combine clearly more portlandite in the first few days, whereas the reaction slows down afterwards compared to K- and Ca-exchanged samples. The early reactivity of the unexchanged zeolite samples could be explained by these two parameters, but their long-term reactivity seemed to be related to their Si/Al ratio. Samples with zeolites rich in Si reacted faster then their Al-rich counterparts.

Jan 1, 2008

By Maurice Bottiau

"Abstract When addressing the performance of deep foundations, many parameters play a role, from adequate soil investigation to performance monitoring and testing. The correct understanding of pile construction, though, remains crucial. After a long period of empirical design and regulations, the last decades have been the ones of theoretical considerations and extensive codes writing. The interaction between technology and design, however, still plays a determinant role. The introduction of hydraulics and the exponential increase in available power on one hand, the miniaturization and the introduction of electronics in control and monitoring systems on the other hand have exerted a major influence on new foundation systems or the evolution and control of existing systems. It appears important to try to take execution related parameters and their control during execution more deeply into account when assessing the final result of the deep foundations and the achieved level of safety and reliability. In this contribution, we will try to analyze how systems, equipment and pile production monitoring and testing can influence the pile performance, and if/how this influence could/should be translated in adapted safety or installation factors. This analysis will run through different categories of piles: driven, augercast and displacement auger piles and bored piles. INTRODUCTIONThe global performance of a deep foundation depends on different aspects (Poulos, 2003):1. Ground investigation2. Design and analysis3. Construction4. Testing5. Performance monitoring6. Remediation and performance enhancementThis paper intends to address the importance of pile construction and the control of it on the final performance of the pile-group of piles. There has been an increasing interest for theoretical analysis over the last 20 years, followed by an increasing impact of regulation and codes. Without denying the importance of the latter, the author wants to point out how installation procedure and project specific parameters can largely influence the reliability of the deep foundation. In this context, detailed and prescriptive standards can miss their objective of intended improvement of accuracy and reliability, but even worse they can adversely impact engineering judgment. In today’s construction world, it is possible to gather installation information which can be of outmost importance for the final deep foundations performance. Therefore, the increase or decrease of installation reliability through adequate pile testing and performance monitoring should be emphasized and should be taken into account in the codes. This is the case already in most advanced codes, but in a limited and insufficiently refined way. After reviewing how codes deal with this issue today, we will show some recent examples of unexpected results due to pile installation. We will try to put these examples into a broader perspective by highlighting some reference and/or recent literature considerations. Finally we will try to summarize how pile testing and installation documentation can increase reliability and attempt to open the debate on how codes could/should allow for more engineering judgment."

Jan 1, 2014

By A. H. Winckers

"The San Nicolás deposit is a complex fine grained polymetallic volcanogenic massive sulphide deposit located in central Mexico.Metallurgical testwork was carried out in 1999 and 2000 to develop a flowsheet. During the course of the metallurgical testwork it became evident that it would be impossible to develop an accurate head gradehecovery based model for the projection of metallurgy. It was suspected that variability in mineral texture was a predominate factor affecting metallurgy. For this reason it was decided to evaluate the applicability of QEM*SEM technology to this test program.This paper summarizes the metallurgical testwork and describes the evaluation and subsequent application of the QEM*SEM technology to characterize the mineral texture throughout the deposit. Finally it is shown how the QEM*SEM data are used in the mine block model to project the metallurgy.The QEM*SEM (Quantitative Evaluation of Minerals by Scanning Electron Microscopy) is an automated image analysis system developed by CSRO which provides quantitative numerical estimates of the compositional and textural properties of the mineral suite which govern the concentration process.INTRODUCTIONThe San Nicolás deposit, was discovered in 1997 through the application of geological and geophysical techniques. The property lies 60 km southeast of the city of Zacatecas on the central Mexican plateau as shown in Figure 1."

Jan 1, 2002

By Osetzky D, Hesp W. R

The treatment of a hydrobiotite containing 0·64 per cent copper with various soluHons showed that a high percentage (up to 90 per cent) of the copper can be extracted under mild conditions (1 M BCI, 85°C) or withsaline solutions (20 per cent by weight NaCI or NH4F, 400°C). The latter results suggest that the copper is incorporated in the interstratified vermiculite of a vermicuHte-biotite mica and the solutions (NaCl and NH4F) which reacted with the vermiculite without attacking the biotite gave the highest extraction yields.In general, extraction yields with saline solutions increased with the temperature (between 100 and 400°C) and duration (3 or 6 days) of the treatment but were not appreciably affected by the initial pH of solutions.The results of RCI treatment especially may have a bearing on the hydrometallurgical treatment of refractory copper ores where copper is tied to gangue silicates.

Jan 1, 1977

By R. M. Owens, J. F. Lupo

The Shirley Basin Uranium mine, located in southeastern Wyoming, USA, was an open pit mining operation consisting of a series of several open pit mines excavated into poorly consolidated sandstones, siltstones, and claystones. Since the initial open pits were developed in 1969, slope failures have plagued the mine and mining operations. These slope failures have persisted into the current mine reclamation period. When the mine was first developed, the open pit slopes were designed to range between 45 to 55 degrees. Numerous slope failures during mine development required the pit slopes to be redesigned with slopes as shallow as 26 degrees. At present, movements are occurring within the open pits on reclaimed slopes that are shallow as 12 degrees. Several detailed slope studies were conducted at the mine in the early 1970s. These studies, combined with more recent geotechnical investigations, provide a unique detailed history of pit slope failures on shallow slopes. This paper presents an evaluation of the slope failures at the Shirley Basin mine, highlighting important mechanisms causing slope failures on very shallow slopes. The evaluation demonstrates important key parameters for shallow slope design.

Jan 1, 2001

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

By A. Mazhary

"Although ore sorting in mining is not a new concept, sensor-based sorting has failed to gain broad acceptance due to perceived challenges with the technology. In order to gain wider applications, this research focuses on treating waste rock and low-grade ore to identify and test appropriate sensors and to evaluate the response. Results showed that amenability of rocks to sensor-based ore sorting is both sensor and ore specific. It was also observed that the efficiency (recovery) of sorting is directly influenced by the degree of heterogeneity of the rocks. The overall outcome showed that with the right sensor, several of the materials tested are amenable to sensor-based ore sorting. Mining companies could benefit from multiple economic and design impacts, such as lower energy cost, lower transportation costs, higher metal recoveries and smaller footprints that lead to more sustainable mining. This paper will focus on the effects of heterogeneity of rocks on sorting potential and efficiency.IntroductionSensor-based ore sorting has been attracting more attention since the pressure for effective resource extraction and management has increased. An urge to make most of the current deposits, and to make the low-grade deposits economic to mine has ushered the technology to find new ways to overcome the new challenges. No matter the terminology used, such as coarse beneificiation, waste rejection, particle or bulk sorting, the purpose of sensor-based ore sorting is to remove low-grade rocks before the comminution circuit, increasing the feed head grade and quality while reducing the energy costs related to comminution.Despite nominal advantages, there have always been some concerns that have impeded the intorduction and acceptance of the technology. One of the most important shortcomings of ore sorting is their capability, or capacity, to keep up with the high-tonnage mining. Some other issues that have been mentioned as drawbacks to sorting include installation cost of such devices, feed preparation for effiecient sorting along with accuracy of sorting and probability of false negatives (Manouchehri, 2003)."

Jan 1, 2015