Search Documents

By Zhen-xing Diao, Feng Zhao, Ya-dong Xue

"Two important aspects of excavation performance of TBM are advance rate and cutter replacement/ring consumption, which is closed to the cost and construction duration of the project. To achieve this, a database of TBM parameters and the geological-geotechnical conditions during the excavation of Yinhanjiwei was compiled and analyzed. Relationships between different geological and TBM operational parameters were investigated. Results of analyzes show that there are qualitative correlation between Field Penetration Index (FPI) and rock geological parameters. And strong relationships between FPI and operational parameters are suggested. In this study, the cutter replacement and ring consumption were analyzed using statistical method for preliminary estimation in similar conditions. 1. ITRODUCTION Hard rock TBM is widely used in tunneling project nowadays because of its advantages to conventional drilling and blasting, especially in long tunnels. The biggest advantage is its high advance rate. However, rock conditions of tunnels are complicated. So TBM performance becomes a primary topic in tunneling engineering, which includes of rate of penetration, utilization, daily advancement, cutter consumption and so on. Many prediction models have been developed to estimate the TBM performance in the project planning phase. The most widely accepted and used models around the world are semi theoretical CSM model (Rostami and Ozdemir, 1993; Rostami, 1997) and the empirical NTNU model (Blindheim, 1979, Bruland, 1998).With increasing uses of TBMs in different ground conditions, an increasing number of researchers have developed new models in order to predict the performance of TBM more accurately in similar geological conditions.(Gong and Zhao, 2009; Hassanpour et al.,2009, 2010, 2011, 2014; Delisio et al., 2013; Delisio and Zhao, 2014)"

Jan 1, 2016

By Nikhil Dhawan, Amit Barnwal

The present study reports a processing route to recover metals from integrated circuits of discarded random access memory (RAM) units containing ~ 66% printed circuit boards and ~ 33% integrated circuits. The integrated circuits are manually separated, grounded, classified, and subjected to water fluidization for the effective separation of metals. The significant separation was achieved via water fluidization, and the underflow fraction was magnetically separated. The magnetic fraction was thermally exposed in a muffle furnace, and the process optimization was carried out using a Box-Behnken statistical design. The detailed characterization at subsequent steps significantly aids the understanding of metal-plastic separation and enrichment. A concentrate containing 97% metals (Fe-59%, Ni-9.5%, Cu-7.7%, Sn-13.4%, Pb-5.6%, Ag-1.6%) with 96 wt% recovery can be recovered from discarded IC units. The process pursued is simple, adaptable, and environment-friendly, and the product can be used in conventional smelters.

Jun 23, 2020

By Leonard Sugin

As we approach the end-of the 20th century we are made more aware of the tremendous role that energy plays both directly and indirectly in our varied way of life. The industralized nations of the world have already established industries and economies which are greatly dependent upon the availability of energy. The underdeveloped and developing nations of the world are slowly and surely moving to the same utlimate requirements. The world wide need for distribution of energy sources is continuing to grow. At the present time there is a great imbalance between the sources of energy and the consuming economies In order to bring about greater equality between supply and demand major efforts and large capital expenditures are constantly being made. Industralized areas are seeking their own independent sources of energy whereas those areas of the world which contain great reserves of energy are limiting its export as well as developing its own industralized capacity. Nevertheless, energy bearing materials are still transported great distances in order to satiate the appetites of power hungry economies.

Jan 1, 1975

By H. A. Taylor

Bismuth, one of the heavier chemical elements, is a pinkish metalloid that is chemically related to antimony. It is a byproduct of lead and tungsten extraction and, to a lesser extent, of copper and tin extraction. Antimony is a metalloid and less heavy chemical element, an extraction coproduct of metals such as lead, silver and gold. While both bismuth and antimony are metalloids, their major uses are as chemical compounds. The most frequently updated resources that always cover bismuth and antimony are the Bismuth Advocate News (BAN) and link at www.basicsmines/bismuth and the frequently updated Basics Mines Update blog at http://basicsmines-update.blogspot.com. The Bismuth wiki on Wikipedia also can be very helpful.

Jan 1, 2010

By B. T. Lusk, J. M. Hoffman, J. Silva Castro

Blast vibration induces sounds within neighboring residences. A housewide vibration and sound monitoring system was installed in a West Virginia home subjected to blasts from various distances and directions. Eighty-nine blast events were monitored and analyzed. Fifteen channels of data were collected, including data from three triaxial geophones, one airblast microphone, one uniaxial geophone mounted on the wall of the house (response channel) and four microphones that recorded CD-quality sound waves inside the house. Each of these channels was recorded on the same time scale. The response channel signal was easily separated into ground vibration and airblast-induced movement, due to differences in the time of arrival. This response channel was then compared to the sounds recorded to determine which component of blast vibration induced the maximum sound response. Blasts at distances less than 762 meters (2,500 feet) had maximum sound responses from both ground vibration and airblast, while for blasts beyond 762 meters (2,500 feet), the maximum sound response was caused by ground vibration without exception. When airblast was identified as the dominant sound generator, the peak amplitude of the sound was directly related to the amplitude of airblast. When ground vibration was identified as the dominant sound generator, the peak amplitude of sound was not related to the amplitude of ground vibration. Findings from frequency analysis showed that the frequency content of sounds inside the house was not related to the frequency content of airblast or ground vibration, regardless of source. This finding suggests that residents will have difficulty determining the source of blast-induced noise in their homes. The proposed airblast response factor (ABRF) can aid blasting operations to determine the dominant source of sounds inside a complainant’s house based on the time-of-arrival relationships. With this site-specific information, public relations responses can be developed accordingly.

Jan 1, 2010

By R. J. Grace

Carbon in the form of coke is used as a reactant in various chemical and metallurgical processes, The high cost of by-product coke along with its periodic lack of availability and high investment necessary for additional by-product recovery facilities indicate the need for a low-cost production unit based on a new procedure for coke manufacture, Traveling-grate coking-stokers were developed by Shawinigan Chemicals Ltd. to produce coke required for carbide manufacture, They were adapted to kilns so that the hot volatile gases could be used for lime burning, Their operation has been described in various patent disclosures (1, 2, 3), and their application to rotary lime burning kilns has been described by Andersen (4). Details of the process and plants have also been published by Kurt Baum (5,6).

Jan 1, 1958

By Krawiec Alfons

The threat of rock bursts along with the danger from methane gas and coal dust explosions belongs to particularly dangerous phenomena in Polish pit-coal mines. This phenomenon results mainly from the physical-mechanical properties of the rock mass as well as the geological-tectonic structure of the Upper Silesian Coal Basin. In the postwar years in Polish coal mining thanks to a multi- directional activity, a decrease of rock bursts and their effects has been noted. For example, the number of rock bursts reported in 1965 amounted to 71 in comparison to only 23 in 1974. The ratio of rock bursts calculated for 100,000 tons of coal extracted from rock bursting strata amounted to 0.08 in 1965; however, in 1974 it amounted to 0.023 /Fig. 1/. These results were obtained in face of a continually growing potential threat from rock bursts caused by the systematic increase of extraction from rock bursting strata, exploitation at gradually greater depths along with the extension of exploitation into deposits enclosed in different types of pillars and other parts of deposits surrounded by workings. Despite the achievements of science and mining practice in this field, this threat has not yet been fully studied and controlled as it should be, As a result, research on preventing rock bursts is being continually widened in Poland. This research has a complex, multi-staged and long-range character. Theory, laboratory and field work in the mines are working on a solution to the problem.

Jan 1, 1976

By C. Garcia, C. L. Lin

Characterization and analysis of multiphase particles and/or particulate systems (such as the packed particle bed) are of great technological importance for mineral processing applications. In general the performance of these applications depends on the statistical characteristics of particle microstructures, such as composition distribution, surface exposure of mineral grains, pore network structure, etc. For continued technological progress in the field of multiphase particulate processes, the need for quantitative spatial analysis of multiphase particles in three dimensions has increased sign6cantly. Such quantitative information must be accurate enough that the measured values can be used as parameters for simulation models, process design procedures, and control strategies. Modern 3D image-acquisition techniques, such as X-ray microtomography (XMT), offer a unique imaging capability that can produce high-resolution (a few micrometers) three-dimensional images of the internal structure of multiphase particulate samples. These three-dimensional image data present new challenges for image analysis, image processing, and visualization. Furthermore, important issues should focus on how to use the 3D information and derive new insights into the improvement, design, and operation of mineral processing processes. In this paper, utilization of XMT for characterization and analysis of leaching process involving multiphase particulate system is discussed.

Jan 1, 2005

By Patricia Pride, Mike Robison, Jon Bergenthal, Wojciech Klecan

"The Lower and Middle River Des Peres (LMRDP) CSO Storage Tunnel is the largest single component of Metropolitan St. Louis Sewer District’s (MSD) CSO control system improvements planned to meet consent decree requirements for MSD’s Lemay Service Area. The 13.7-km (8.5-mile) long, deep, hard rock tunnel will have a finished diameter of 9.1 m (30 ft). Beginning at the Lemay Wastewater Treatment Plant (WWTP), the alignment follows the channelized River Des Peres to the outfall of the existing Forest Park tubes, as indicated in Fig. 1.The project includes three construction shafts, 34 intakes and a deep, cavern-style pump station located adjacent to the WWTP. The tunnel will be driven from the Defense Mapping shaft to the Macklind shaft. Another shaft is located near the midpoint at the tunnel in River Des Peres Park.The Forest Park intake, located at the upstream end of the tunnel just beyond the Macklind shaft, is a large, tangential vortex intake structure. With a peak flow rate of 170 m3/s (6,000 cfs), it will have a 6.1-m (20-ft) diameter dropshaft to transfer flow into the tunnel.The project includes another three large tangential vortex-flow intake structures with peak flow rates ranging from 28 to 44.5 m3/s (990 to 1,570 cfs). These large intakes are located at points where three large sewers (formerly creeks) enter the River Des Peres. Dropshaft diameters for these intakes range from 3 to 3.7 m (10 to 12 ft) in diameter. The 30 remaining intakes are smaller tangential vortex-style, with dropshafts in the range of 0.8 to 1.7 m (30 to 66 in.) in diameter.Each intake structure drops flow into a deaeration chamber constructed adjacent to the tunnel at tunnel depth. Intake tunnels transfer flow from the deaeration chambers to the main tunnel. Most of the intake tunnels are short. However, two are long. The Glaise Creek tunnel will extend 762 m (2,500 ft) from the main tunnel to the Alaska Park intake, while the Rock Creek tunnel will extend 823 m (2,700 ft) from the main tunnel to the Rock Creek intake. The dewatering pump station, located at the downstream end of the tunnel, will be built inside a large, horseshoe-shaped cavern with two access shafts. Excavation of the cavern and its access shafts will be performed by the tunnel contractor. Build-out of the dewatering pump station will be performed under separate contract."

Jun 1, 2019

Smart defense: that?s what the industry needs to play for the next four years, according to panelists at the 118th Annual Meeting of the Northwest Mining Association (NWMA), which met December 2-7 in Spokane, WA. The conference was well attended, with approximately 2,200 attendees, 244 booths in the two packed exhibition halls, and a rich offering of short courses, field trips, social events and technical sessions. Speakers at the packed legislative session articulated many of the frustrations felt by members of the mining community after the U.S. elections in November, and offered words of advice. Matthew Ellsworth, the new Government Affairs hire at NWMA, stated it best: ?Elections are like Christmas: you find out who?s naughty and nice ? and it?s always going to come again.?

Jan 1, 2013

By Donald W. Gentry

The evaluation of industrial minerals deposits for investment decision making follows the same basic principles that apply to metallic deposits. For example, the quantity and quality of the mineral occurrence is assessed, engineering/economic feasibility studies are performed for various production scenarios, project evaluation criteria are calculated for each alternative, and finally, an investment decision is made. A more specific evaluation-related example of commonality between metallic and nonmetallic deposit assessment relates to the various parameters which impact project feasibility studies. There exists a suite of pertinent factors which must be considered, studied, and analyzed when evaluating any mining property. Table 1 is an outline of some, but certainly not all, of the various factors which should be considered when preparing feasibility studies on mining properties. Most analysts agree that all the factors listed in Table 1 should be assessed to some degree in at least one of the feasibility studies prepared during the property's evaluation period.

Jan 1, 1984

By M. Eyll-Vetter

The operation of large opencast mines in a densely populated area in the centre of Europe involves an inevitable interference in the region. Thus, this is only possible with general acceptance by the regional stakeholders. In order to achieve this general acceptance, it is necessary to develop sound common concepts and to engage in a continuous dialogue with the stakeholders. The aim is to create seminal structures of relevance to the regional economy, taking into account the interests of the various stakeholders like e.g. authorities, local governments, the regional public, and churches. The recultivation of the mined-out areas represents the offset for the mining activities. RWE Power has reached high acceptance of its recultivation. This high acceptance is illustrated by various examples, from biotopes to high-yield agriculture and recreational areas. Thus, recultivation covers all the elements of sustainable development from social compatibility to ecological as well as economic aspects. This is only achievable through an intensive stakeholder dialogue in the region: The communities concerned are intensively involved in the planning and approval process for the new landscape. As far as social compatibility - one of the aspects of sustainable development - is concerned, the necessary resettlement of whole villages is one of the principal challenges. Over the last few decades, RWE Power has developed an approach that is broadly recognised by the stake-holders in the region. The best proof for this is the high proportion of resettlees taking part in the joint resettlement scheme offered. This can only be achieved by constant involvement of the stakeholders in the resettlement process. In conclusion, it can be stated that RWE Power has implemented a well-functioning stakeholder dialogue that guarantees the general acceptance necessary for mining operations.

Jan 1, 2007

By Donald E. Ranta

An ore zoning technique developed by Climax geologists during the past forty years has been used to contour drill-hole assay values on cross-sections for fourteen porphyry molybdenum deposits in western North America, including the Climax and Henderson orebodies. Detailed geological studies of these large, complex deposits are essential in determining ore controls, which are the factors most critical to the zoning of MoS2 assays and to conceptualizing geologic models. The technique provides a detailed representation of the size, shape, grade distribution, and geologic continuity of the individual deposits. It demands a disciplined approach and adheres to rigorous rules while maintaining flexibility for adaptation to widely varying geologic conditions. By defining the limits that guide and control manual, computer-assisted conventional, and geostatistical reserve estimates, it exerts a strong geologic influence on the estimation process. A combination of ore zoning and geostatistical analysis of molybdenum deposits produces a significantly more accurate, precise, and defendable geologic reserve estimate than other methods.

Jan 1, 1983

By Danqing Gao, Brijes Mishra

Spatial variance of rock properties is an important characteristic of rock which addresses the heterogeneity of mechanical and physical properties and their effect on underground mining. Assessing spatial variance can be useful for both locating potential difficult grounds and performing reliability analysis in the mining support system. This study shows a microscale numerical model for rock material based on continuum mechanics. To consider the spatial correlation factor of mechanical properties in realistic rock mass, this study introduces a spatial correlation concept into the traditional type III extreme value distribution model. Based on the improved microscale random model, we conducted a series of numerical uniaxial compressive tests and one longwall mine model to investigate the progressive failure of rock. The results show that spatial correlation factor can significantly affect the load-deformation curves and fracture patterns. The spatial variance model was applied to a longwall mine that included several cutting sequences to observe the influence of the spatial variance on roof behavior. The cohesion and friction random fields induced failure that propagated randomly through the immediate roof in different entries. The results showed that the spatial variance provides an accurate prediction of erratic roof falls in coal mines.

Jul 20, 2020

By Cloyd D. McDowell

The Federal coal Mine Health and Safety Act of 1969 has been criticized by those who say it goes too far in controlling the activity of private enterprise and by those who say it does not go far enough in eliminating fatalities and accidents in an accident prone industry. Possibly a better evaluation of this legislation lies somewhere in between. From the viewpoint of the coal industry it can be said that through the efforts of those engaged in mining, both the operator and the miner, the year 1969 marked a record year in mine safety with only 190 fatalities and a frequency of 0.84 per million man hours exposure. This outstanding achievement compared to any previous was the result of a determined effort on the part of a concerned industry to improve its reputation as being the most hazardous industry in the nation. After the effective date of the Act, March 31, 1970, the Bureau of Mines assumed complete control of all safety and health activities of the mining industry. Unfortunately, there was no improvement in the safety record of underground mines in 1970 with the total of 255 fatal injuries and a frequency of 1.04 for the year. The number of fatalities declined to 177 in 1971 but the number of underground coal mines had declined from 5,955 to 2,268 during the two year period. Meanwhile, surface mined coal increased from about 38% of total production in 1969 to over 50% in 1971, keeping the annual production of coal at a normal level but involving fewer men.

Jan 1, 1973

When looking for indicators for the mining business ? and these days who isn?t? ? one might need to look no further than the SME Annual Meeting. Held in Phoenix, AZ Feb. 28 to March 3, the meeting was, by almost any measure, a record-breaking success. Attendance included 4,937 industry professionals. Many of whom, feeling rejuvenated following the worst economic recession since the great depression, were greeted with a record 630 exhibits and 103 technical sessions covering all aspects of the mining and minerals business. Adding to the general optimism of the future was a celebration of the past and re-cent achievements in safety and health. The theme of this year?s meeting was ?Celebrating 100 Years of Mining Research? and the emphasis on advancements in safety was evident from the keynote address that kicked off the conference, to the field trips, to the Resolution and Safford mines that concluded the meeting.

May 1, 2010

By J. Chai, Q. Yuan, B. Qiu

"Overburden strata deformation monitoring is one of the key problems in ground control. Using geophysical method through surface drilling to detect strata deformation is commonly used in the industry. In this paper, a geophysical method based on the distributed optical fiber sensing (DOFS) system were conducted in the laboratory, where a DOFS-based strata deformation monitoring experiment was performed with three physical models. The results show that the DOFS method precisely detects the rock mass deformation and strata structure forming with the Brillouin frequency shifts (BFS) representation. The BFS curves are divided into three phases, which reflects the horizontal three zones developed in the overburden. The BFS distribution presents a multiple stages form, the 1st stage corresponds to the caving zone and the 2nd stage corresponds to the fracture zone. Based on the multiple stages form, the evolution of the water flowing through fractured zone have been determined and the controlling effect of key strata over the water flowing fracture has been pointed out. In the end, the comparison validation proves the accuracy and reliability of this method, and it could be a new approach for the ground control research. INTRODUCTION Overburden rock strata above the work face space will propagate from slight deformation, part destruction to violent movement because of the underground coal mining. It is fundamental and an intrinsic requirement of ground control to monitor the mining-induced rock mass deformation.[1] Overburden strata have their significant mechanical behaviors and movement under damage deformation and fracture. Overburden strata deformation affect the mining ground pressure control directly, and performance in the relationship of supporting equipment and the surrounding rock, the mining-induced fracture distribution and the loss of underground water resource, the ground surface structure stability and the ecological environment.[2] From the perspective of the concept of safe and efficient scientific coal mining: the overburden strata deformation is an important part of mining method selection and reasonable supporting solutions decision which can solve the issues like the roof supporting force calculation, overburden fracture distribution and gas drainage, ground subsidence, separation of coal and rock control and top-coal recovery rate and so on. From the perspective of green and ecological mining: the overburden strata deformation is the key basis of studying the mining-induced ground subsidence and mining area ecological damage, and such engineering problem like environmental protection in mining area, ecological restoration in mining subsided land and the water conservation in fragile ecology area of mining could be solved based on it.[3-6] Therefore, the mining-induced overburden strata deformation is the key of ground control and needs to be controlled artificially."

Jan 1, 2017

By Paul Soros

There has been a steady increase in shiploading capacities in the last 20 years. One of the reasons has been the general increase in ship sizes, with the largest vessels currently around 280,000 DWT in the bulk trades. Obviously, the large vessels can accept loads faster and their economic utilization justifies higher loading rates, up to a point. The high capacity facilities have loading rates far beyond this point. The economic logic of these facilities is based on the fact that for a given annual throughput the capital and operating cost of a single high capacity system is less than that of two smaller systems. Thus, where the projected throughputs are large, there is a great incentive to reduce capital costs by maximizing capacity. Tubarao, in Brazil, designed for a 100 million ton per year throughput with one finger pier and one high capacity berth is a successful demonstration of this approach. In the current state of the art, the high capacity systems have shiploading capacities in the range of 10,000 - 16,000 TPH, for annual throughputs of 20 million tons and larger per loading berth.

Jan 1, 1982

By J. F. Mack, P. R. Michael, J. M. Shapaka, S. J. Self, M. W. Richmond

"On October 11, 2000, an estimated 306 million gallons of water and coal waste slurry drained from an impoundment in Martin County, eastern Kentucky into an adjacent underground mine. Approximately 230 million gallons of the water and slurry discharged from two underground mine portals and affected over 75 miles of streams in Kentucky and West Virginia. In response to this and several other similar events, the U.S. Office of Surface Mining Reclamation and Enforcement (OSMRE) commissioned an oversight study that evaluates how well state and federal regulatory programs established under the Surface Mining Control and Enforcement Act are ensuring that impoundment operators are minimizing the potential for impoundment-basin breakthroughs. The study focuses on slurry impoundments constructed in the hollows of Appalachia where numerous coal seams and steep topography combine to result in a large number of mined seams intersecting and underlying impounding facilities. Factors under consideration include: (1) full accounting of all mineable coal seams intersecting and underlying the impoundment; (2) identification and accurate location of underground mines close enough to the impoundment to potentially affect its stability; (3) assessment of the stability of coal barriers between the impoundment basin and adjacent mines, and stability of roof rock and pillars in mines subjacent to the structure; (4) determination of the flowability of the impounded slurry when expanding or undermining the facility are being considered; and (5) measures undertaken to reduce breakthrough potential when necessary. The oversight study began in 2012 after program-evaluation criteria were defined in an OSMRE technical position paper. The study is scheduled to be completed in 2017. BACKGROUND The Surface Mining Control and Reclamation Act (SMCRA) authorizes the disposal of coal mine waste by constructing a coarse coal mine waste embankment across a valley and pumping the fine coal mine waste (slurry) into the resulting basin (Figure 1). A concern shared by many engineers, geologists, and mine inspectors familiar with coal mine waste slurry impoundments is related to the common occurrence of underground mine workings adjacent to or beneath the impoundment: the potential for slurry “breakthroughs” into mine works and subsequent breakouts into the surface waterways (Figure 2). On October 11, 2000 a combination of coal refuse slurry and water from the Big Branch impoundment in Martin County, Kentucky broke through into an underground mine and subsequently discharged into the receiving streams. The location of the point of breakthrough, pathways of slurry/water flow within the mine workings, and two points where the liquid exited the mine are shown in Figure 3. An estimated 306 million gallons of water and coal refuse slurry drained from the impoundment into the adjacent underground mine. Approximately 230 million gallons subsequently discharged from the underground mine at two portals."

Jan 1, 2015

By T. Takamori

This paper reviews the present status of coal preparation in Japan concentrating on the process in coal cleaning and waste water treatment. This paper also discusses recent topics on maintenance, automatic control, raw coal management, etc.

Jan 1, 1982