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By Seung-Kyu Son, Michael T. Chandler, Youngtak Ko, Gyuha Hwang

Over the past decade, sea-floor hydrothermal vent fields have been studied by many researchers because of their commercial potential of mineral resources and the origins of Earth’s life. Approximately 300 of these are reported as massive sulfide deposits near the mid-ocean ridge, most of which are located in the Atlantic and Pacific ridges. However, only fourteen deposits have been identified in the Indian mid-ocean ridges. The Central Indian Ridge (CIR) between 8°S and 12°S is composed of three segments with a slow full- spreading rate of 33-37 mm/yr. The hydrothermal activity at the slow-spreading center can be generated along the ridge axis attended by volcanism or along the tectonic features, such as oceanic core complexes (OCCs). OCC is an exposed mantle rocks composed of peridotite and ultramafic rocks uplifted through long-lived detachment fault processes which can also lead to extensive hydrothermal circulation near the slow-spreading center. Therefore, the identification of OCC’s properties will be an important indicator for finding the sea-floor hydrothermal vents. To study hydrothermal activity of the CIR, Korea Institute of Ocean Science and Technology (KIOST) have conducted expeditions using R/V Onnuri over four years (2009-2011, 2017). High-resolution bathymetry and backscatter data was obtained during expeditions using multibeam echo system of EM120 in 2009-2011 and deep-tow side-scan sonar system of IMI-30, which has more higher resolution than EM120, in 2017. In this study, we use these high-quality data for constraining location and size of OCC. We also analyze the geophysical and morphotectonic characteristics of OCC gathering high-resolution bathymetric map and backscatter image.

Jan 1, 2018

By David K. Ingram

The objective of this U.S. Bureau of Mines investigation was to characterize overburden response due to longwall mining. Subsurface strata and surface deformations were monitored during the mining of two adjacent, 900 ft wide longwall panels in southeastern Ohio. The panels were separated by a five entry, four pillar system (about 350 ft wide). The overburden thickness in the study area ranged from 214 to 280 ft, and the extraction thickness averaged 70 in. To delineate the geology of the overburden, six coreholes were drilled along a profile line extending across the two longwall panels. Multi-point borehole extensometers (MPBX) with eight-anchors were installed in six boreholes to measure subsurface displacements. The MPBX units were continuously monitored using a data logger. During the mining of the first panel, displacement occurred in a radiating pattern beginning just above the extracted area in the center of the panel and extending upward and outward towards the surface and margins of the panel. Overburden deformation did not project over the gate road entries. During the mining of the second panel, the MPBX's showed almost simultaneous displacement, indicating that the overburden began to move as a whole unit. Again, overburden deformation was confined to the immediate panel area. At both panels, overburden movement began when the longwall face was approximately 55 ft beyond the line of MPBX boreholes. Moreover, all ground movement was complete when the longwall face was approximately 200 ft beyond the line of MPBX boreholes. This paper discusses the results of the study and identifies the characteristics of overburden deformation.

Jan 1, 1986

By Dan E. Lewis, William E. Saegart

Similarities of certain geologic and mineralogic parameters are recognized among the various Philippine porphyry copper deposits. Lowell and Guilbert3 described a model of the typical porphyry copper deposit as the result of comparing numerous Western Hemisphere occurrences. Many of the characteristics of the Philippine porphyry copper deposits differ from the model developed by Lowell and Guilbert. A model of the typical porphyry copper deposit is presented and the characteristics of the Philippine model are compared with those of the Western Hemisphere model. Estimated Philippine copper production in 1975 was 242 446 mt. The total in 1948 was 2091 mt. This represents a 116-fold increase in copper production during the 28-yr period. The Philippines now rank seventh in total world production of copper.

Jan 1, 1978

By William E. Saegart

Copper has been mined in the Philippines since at least as early as the Ming dynasty (1368 A.D. to 1644 A. D.). The principal source areas of this early production were in Camarines Norte (Paracale), in the Mountain Province, which now boasts the largest number of Philippine porphyry copper deposits, in Masbate and in Surigao, The Spanish Era began in 1521. Although they were primarily interested in gold, the Spaniards operated several copper mines including the San Remigio mine on Panay and the Lepanto mine in northern Luzon, beginning in 1842 and 1865 respectively. Prior to World War II most of the Philippine copper production was supplied by these same two mines together with the Hixbar mine, Rapu Rapu Island which began operation in 1939. The Hixbar and San Remigio mines are cupriferous pyrite deposits and the Lepanto is a vein-¬form replacement deposit (Kinkel et al. ,I 1956). No significant copper production was derived from porphyry copper occurrences prior to world War II.

Jan 1, 1976

By H. L. Lovall

Huge banks of preparation plant refuse and other non¬saleable materials have accumulated over the years in all major United States coal producing areas. These banks, esthetically and commercially undesirable, can cause air and water pollution and land reclamation and mineral conservation problems for the industry and nearby communities Although some refuse banks have been reworked to recover saleable coal, all remain and accumulation continues. Even those previously processed continue as potential hazards. Among the several problems created by refuse banks, in situ combustion is most treacherous. Of the millions of tons of major accumulations, there are at least 450 refuse banks on, fire at this time Attempts to extinguish such fires are costly, impractical and generally unfruitful. Studies are in progress to evaluate the potential of processing such materials to eliminate the combustion capability and to yield usable fuel and nonfuel products. Aspects of the study now in. development for coal refuse include: (a) evaluation of characteristics (size, sink-float, ash, sulfur and calorific value) of the coal refuse materials which are known to be highly variable, (b) development of an ignition test having significance for in situ conditions, (c) study of processing capabilities (comminution for liberation, pilot plant washing tests), and (d) investigation of potentially significant properties of fuel and nonfuel products which could be altered to enhance their market potential.. Among the latter products are lightweight aggregate, fill for mine slushing operations, construction, etc: Plans are to extend the studies to include the design, erection, and test processing of refuse with a transportable plant,; which could provide basic economic and product utilization data from several locations

Jan 1, 1964

By G. Dodbiba, T. Fujita, M. Kawata, S. Yamasaki, K. Mitsuhashi, J. Ponou, Y. Iwazaki, T. Atarashi

"The grade of copper ore and concentrate is recently decreasing and it will continues decrease further in the future. The effective liberation treatment for low grade copper ore and the removal of arsenic from copper concentrate is becoming even more important. In this work, the magnetic separation of copper concentrate by heat treatment and the flotation of low grade copper ore by microwave irradiation was studied. The heat treatment of copper minerals in the air atmosphere, the magnetization of most copper minerals increases and especially the magnetization of chalcopyrite shows the largest magnetization, after being heated at 500 oC. The wet HGMS of copper concentrate has been studied and the results have then been compared with the ones when calcined concentrate was used instead. The microwave treatment before ball milling increased the degree of liberation up to 100%, especially when compared with the case when only ball mill was applied to the as-received ore. The flotation of ground copper ore after microwave irradiation showed that the grade copper minerals such as chalcosite and bornite in froth part is much larger than that of tailing part.INTRODUCTION The copper has been used many kind of technological fields and will be more important for the future technology. The global copper production from mine is predicted as shown in Figure 1 (Northey, S. 2014). The copper production peak will be appeared in 2030 and the demand peaks in 2040. In the future the recycling of stocked copper and copper alloy will be necessary to satisfy the demand (Yoshimura, A. 2018). Changes in the grade of copper in copper concentrate, exported from several countries are shown in Figure 2. The copper grade in copper concentrate after mineral processing is gradually decreases every year and it is less than 30% nowadays. On the other hand, the copper ore grade change and prediction are shown in Figure 3. The grade of copper ore is also decreasing to less than 1% in 2010 (Northey, S. 2014). In the future the copper grade gradually decreases, reaching to less than 0.5% in 2080 and the energy to produce the copper metal will increase. The effective liberation treatment for low grade copper ore and the removal of arsenic from copper minerals become more important, nowadays. The microwave irradiation of copper ore for the liberation, energy etc. has been reported by several researchers (for example, Batchelor, A.R. 2017). The magnetization change of copper ore by heating has been reported to remove the arsenic (Sawada, M 2015). In this report, the magnetic separation of copper concentrate by heat treatment and the flotation of copper concentrate by microwave irradiation are discussed after the characteristics of secondary copper minerals are investigated by these treatments."

Jan 1, 2018

By Jiulong Cheng

Underground coal mining causes overburden deformation and failure, one major form of which is bed separation in the overburden. Surface subsidence can be controlled by injecting grout into the bed separations. For a long time, the grouting results of bed separation can not be validated. This is the problem in the application of this technique. This paper analyzes the conditions leading to bed separation, develops mathematical models for seismic wave fields generated before and after bed separation, and bed separations grouted with different materials, and computes the seismic wave field characteristics using the finite difference method. The results show that the existence of bed separation causes changes in the characteristics of seismic wave field, and that different grouting materials generate different seismic wave field characteristics. Intact strata, bed separation, and bed separation filled with air or water all display distinctive seismic wave field in amplitude and frequency spectra. After mining, the original location that provides strong seismic reflection wave no long exists. It is replaced by a weak and syncline-shaped reflection wave. The area, where the seam wave disappears, is larger than that of the mined area. The location, where a bed separation occurs, generates a set of reflection waves stronger than the normal one. The energy of the reflection waves varies with the materials filling the separations. Bed separations filled with air generate stronger reflection waves than those filled with water. The major frequencies for those filled with air are lower than those filled with water. Therefore, it is possible to determine the property of filling materials by analyzing and comparing the amplitude and frequency spectra of the reflection waves. Case studies of application of seismic method for exploring bed separations and grouting were analyzed. The results show that it is feasible to use seismic technique for exploring bed separations and grouting.

Jan 1, 2006

By I Canbulat, G Si, Y Duan, X Luo

The presence of unfavourable geological structures such as faults and dykes often can contribute to coal burst risk. Seismic events associated with rock fractures tend to cluster around these structures and it is important to understand the characteristics of seismicity for coal burst risk management. In an Australian underground longwall coalmine, two clusters of seismic activities close to the longwall face and within a section of the maingate roadway which was intersected by a major dyke were respectively identified. The induced seismicity in the dyke-roadway area was closely related to the longwall mining. These seismic events were located and the distribution of seismic events shows that more fractures were distributed on the inbye side of the dyke. The spatial-temporal changes of the seismic event locations delineate the fracture propagation as the longwall mined through the dyke. The frequency-magnitude relationship of seismicity was analysed and it was found that it changed significantly when the longwall was mining towards, through and past the dyke. The monitoring results demonstrate that because of the stiff dyke, the seismicity was intensified in the roadway section. It proves that the dyke promoted stress re-distribution and seismicity in its vicinity. More fractures were induced in the hanging wall of the dyke, whereas less strain energy was accumulated and released in the footwall of the dyke.

Nov 29, 2022

By A. R. Naji Meidani, A. Cameron, A. Richardson, M. Isac, R. I. L. Guthrie

The supersonic core of shrouded jets remain coherent over longer distances vs conventional supersonic jets. This phenomenon should allow for greater penetration of oxygen into slag/steel reactor systems. As such, they hold the promise for faster slag/metal mixing in BOF type metallurgical reactor systems, possibly creating greater surface area/volume ratios of reacting phases, and thereby faster kinetics, as compared to conventional supersonic jet systems. In order to assess the potential of shrouded supersonic jets versus their conventional counterparts, an experimental investigation of impinging shrouded supersonic jets into a water model of a simplified BOF system was carried out in the MMPC's water modelling laboratory. The experimental results for three different designs of a shrouded supersonic jet nozzle have been compared in terms of greater penetration depths and reduced mixing times. Based on a novel dimensional analysis, the depth of penetration of a gas jet into a liquid bath is shown to depend on the nozzle-bath distance, the liquid's Froude, Reynolds and Weber numbers, reflecting the ratios of gravity, viscous and surface tension forces to the jet's inertial, or momentum, forces. Good agreement between the mathematical model and experiment was obtained in terms of predicted and observed depths of penetration. Further efforts have been made to study jet penetration into liquid metals. The effects of mean liquid density of slag/metal mixtures and a wide range of gas flow rates on the penetration depth were investigated theoretically. The results show that the penetration depth can be increased with increasing gas flow rate and decreased bath density.

Jan 1, 2004

By Xiao Hong, Zhang Wenqiang, Gao Bing

The characteristics of top charging coke (coke 1) and stamp charging coke (coke2) were investigated. The weight loss ratios of two kinds of cokes with and without alkalis were measured after reacting with CO under the temperature of 2 900, 1000, 1100 and 1200 °C respectively. The microstructures of original cokes were observed by SEM. The experiment results show that, with no addition of alkali, the weight loss ratios of coke 1 and coke 2 were nearly the same under the temperature of 900 and 1000 °C. While the weight loss ratio of coke 2 was much larger than coke 1 under the temperature of 1200 °C. With alkali-rich, the weight loss ratio of the two cokes was almost the same at 1100–1200 °C.

Mar 1, 2017

By Mu Chen, Ye-Shuang Xu, Dong-Wei Hou, Shui-Long Shen, Huai-Na Wu

"This paper presents a laboratory investigation on the mechanical behaviors of the cement-clay admixture improved by polypropylene fiber. Cement can significantly improve the clay admixture. The fiber additive also improves the strength and ductility of the improved clay. The Unconfined Compression Strength (UCS) of the polypropylene fiber-reinforced cement-clay presents an overall trend to grow with the increase of fiber length. The improved clay reached its peak strength at the fiber content of 0.5%. Then the UCS of the improved clay will slowly reverse if the fiber content continues to rise. For study of curing time, improved clay behaves better in its early strength, but an inhibition will be brought about if fibers are excessive.INTRODUCTIONGround improvement technology is essential for construction of structures in soft ground. Some traditional techniques often cost much but result in little. For instance, along the coastal region of China, soft ground is often improved by backfill with high quality sandy soil transported far away, leading to high additional haulage costs and long construction period. Reutilizing the excavated soil as backfill or subgrade after treatment, by contrast, will be more economical and effective (Hufenus et al., 2006). Many researches have been conducted to improve the compression strength of soft soil, among which, the method of mixing the soft soil with cement and fly ash is one of the most common ways (Kolias et al., 2005; Horpibulsuk et al., 2009; Porcino et al., 2012). It is known that soil resists well against compression and shear force but behaves poorly in resistance to tension. Therefore, utilizing tensile elements such as fibers and strips to improve the tensile strength will be effective because of its strength isotropy, better durability and cost effective (Haeri et al., 2000; Kaniraj and Havanagi, 2001; Consoli et al., 2010)."

Jan 1, 2015

By Mu Chen, Ye-Shuang Xu, Dong-Wei Hou, Shui-Long Shen, Huai-Na Wu

"This paper presents a laboratory investigation on the mechanical behaviors of the cement-clay admixture improved by polypropylene fiber. Cement can significantly improve the clay admixture. The fiber additive also improves the strength and ductility of the improved clay. The Unconfined Compression Strength (UCS) of the polypropylene fiber-reinforced cement-clay presents an overall trend to grow with the increase of fiber length. The improved clay reached its peak strength at the fiber content of 0.5%. Then the UCS of the improved clay will slowly reverse if the fiber content continues to rise. For study of curing time, improved clay behaves better in its early strength, but an inhibition will be brought about if fibers are excessive.INTRODUCTIONGround improvement technology is essential for construction of structures in soft ground. Some traditional techniques often cost much but result in little. For instance, along the coastal region of China, soft ground is often improved by backfill with high quality sandy soil transported far away, leading to high additional haulage costs and long construction period. Reutilizing the excavated soil as backfill or subgrade after treatment, by contrast, will be more economical and effective (Hufenus et al., 2006). Many researches have been conducted to improve the compression strength of soft soil, among which, the method of mixing the soft soil with cement and fly ash is one of the most common ways (Kolias et al., 2005; Horpibulsuk et al., 2009; Porcino et al., 2012). It is known that soil resists well against compression and shear force but behaves poorly in resistance to tension. Therefore, utilizing tensile elements such as fibers and strips to improve the tensile strength will be effective because of its strength isotropy, better durability and cost effective (Haeri et al., 2000; Kaniraj and Havanagi, 2001; Consoli et al., 2010)."

Jan 1, 2015

By Xuanxue Mo, Kaihui Yang

"Abstract- The Laochang mine, located in the Sanjiang area of southwestern Yunnan Province of China, is a volcanogenic massive Pb-Zn-Cu sulfide deposit. It is hosted by a pyroclastic sequence of Barly Carboniferous age, namely the lower member of the Yiliu Group, which was intruded by syenite and rhyolite porphyry . The volcanic suite is basaltic or basaltic-andesitic in composition, has alkaline affinities, and is associated with the initial rifting along the margin of the Baoshan-Shanstate continental rnicroplate (Yang, 1989). The ores are typically Pb>Zn>Cu in composition, averaging 3.820Jo Pb, 3.51% Zn, from 0.01% to 1.85% Cu (0.107% av.), a high average content of Ag (113 g/t) and recoverable amounts of Au, Tl, Gd, Ga, Ge, In. A massive sulflde zone, in which lenticular and stratiform orebodies are localized in a sulflde-carbonate-silica shale unit or sulfldic tufflte horizon that usually overlies coarse-grained pyroclastic rocks, is underlain by a stringer sulflde zone developed in a subvolcanic intrusion or volcanic sequence. The sulfide mineral assemblages, from the top to the bottom of the deposit, are: realgar + orpiment - galena + sphalerite + pyrite- chalcopyrite + pyrite + pyrrhotite + arsenopyrite. Oxide and sulfate minerais occur rarely in the massive ores. The massive ores are generally fine-grained and banded, but coarse-grained ore, colloform and framboidal texture, and growth-zoned pyrite and sphalerite are common. Sedimentary features such as graded bedding, brecciated and deformed ore clasts, and chaotically emplaced blocks, are well preserved, indicating that the massive orebodies have undergone slumping and dis­ placement. Alteration is weak in the hanging-wall rocks, but strong in the stringer zone. Two dis­ tinctive alteration zones have been identified: the upper zone, characterized by an assemblage of quartz, carbonates, chlorite, albite, zeolite and sericite, and the lower zone containing diopside, trema­ lite, actinolite, gamet, clinozoisite, and epidote.The general features of the Laochang deposit are in accord with the descriptive mode! of VMS deposits (Lydon, 1984). However, it falls into neither the Zn-Cu group nor the Zn-Pb-Cu group chemically (Franklin et al., 1981). The depositional setting of the Laochang deposit is quite different from Cyprus or Besshi-type massive sulfide deposits. Laochang is hosted by alkaline lavas that were erupted in a submarine continental rift. Although some features of the Laochang deposit are similar to those of Kuroko-type deposits, there are remarkable differences in the alteration mineral assemblage, the proportion of ore-forming elements (lead enriched) and the amounts of oxides and sulfates. These suggest corresponding differences in ore fluid composition and the associated ore-forming environment. Thus, the authors suggest that the Laochang deposit may be a distinct type of VMS deposit."

Jan 1, 1993

By McLeod RL

The Tolukuma gold-silver prospect is located approximately 100km N of Port Moresby in the Central Province of Papua New Guinea (PNG). Epithermal "adularia-sericite" style mineralisation crops out over 1200m within an en echelon quartz veined zone 1 to lOm wide. At a 4g/t cut-off grade, a geological resource of approximately 1.47Mt @ 13.77g/t Au is indicated from 38 diamond drill holes completed since discovery by Newmont Pty Ltd in September 1986. At a regional scale, Tolukuma miner- alisation appears localised in a dilatant zone at the intersection of a 1150 magnetic structure, and the western margin of a N-S trending graben which is filled by a Pliocene volcanic complex contemporaneous with the Mt Davidson Volcanics 30km to the W. A l0km diameter circular Landsat feature, which may reflect magma emplacement at depth, occurs immediately N of Tolukuma and nearby mineralisation. Mineralisation at Tolukuma occurs in sub-vertical quartz veins at, or adjacent to the faulted contact between Pliocene basic and intermediate volcanics/intrusives, and quartz mica schists and phyllites of the Cretaceous Kagi Metamorphics. Most veins display evidence of multiple episodes of brecciation and textures indicative of cyclic boiling, including crustiform rhythmic banding and quartz pseudomorphs after platy calcite.

Jan 1, 1991

By P. J. Coleman

Research in the field of mining safety and health in the United States plays an important part in protecting the lives of miners. The National Institute for Occupational Safety and Health (NIOSH) Mining Program conducts surveillance, studies and developmental work aimed at improving the safety and health of miners. With recent reviews of the Mining Program by the National Academy of Sciences and the Mining Program response (NIOSH, 2008), the importance of setting goals, conducting high quality engineering and scientific research and evaluating the outputs, outcomes, relevance and impacts of these projects has been reemphasized. Surveillance of reported injuries is a first step in deciding on research directions and in designing specific projects. Groups of injuries often share features and attributes that suggest common causes and may respond to similar preventive efforts. Identifying groups of injuries also serves to prioritize intervention efforts. The Mine Safety and Health Administration (MSHA) Accident and Injury database (MSHA, 2008) provides individual case reports of mining injuries, illnesses and certain no-injury accidents (events such as roof falls that stop mine production or miners? activities for more than one hour). This database is an indispensable resource for researchers and stakeholders needing information on the statistics of these events. From an epidemiological perspective, research projects target groups of miners at risk due to specific patterns of work, equipment, mine settings and the management of safety and health in their mines. Incidence rates are provided by the MSHA data for selected variables, such as surface/underground location, standard industrial classification and state. While incidence rates are the preferred measure for all variables, denominators are not typically available; for example, to more clearly under-stand the data about injury by occupational type, it would be necessary to conduct demographic surveys. A current survey of the demographics of the mining industry should be complete by 2010, which will allow incidence rates to be developed for a number of variables such as age, occupation and experience. This survey will provide the first update of its kind since the first survey was conducted in 1985.

Jan 1, 2010

By J. Brune, P. J. Coleman, L. Martini

Research in the field of mining safety and health in the United States plays an important part in protecting the lives of miners. The National Institute for Occupational Safety and Health (NIOSH) Mining Program conducts surveillance, studies and developmental work aimed at improving the safety and health of miners. With recent reviews of the Mining Program by the National Academy of Sciences and the Mining Program response (NIOSH, 2008), the importance of setting goals, conducting high quality engineering and scientific research and evaluating the outputs, outcomes, relevance and impacts of these projects has been reemphasized. Surveillance of reported injuries is a first step in deciding on research directions and in designing specific projects. Groups of injuries often share features and attributes that suggest common causes and may respond to similar preventive efforts. Identifying groups of injuries also serves to prioritize intervention efforts. The Mine Safety and Health Administration (MSHA) Accident and Injury database (MSHA, 2008) provides individual case reports of mining injuries, illnesses and certain no-injury accidents (events such as roof falls that stop mine production or miners’ activities for more than one hour). This database is an indispensable resource for researchers and stakeholders needing information on the statistics of these events. From an epidemiological perspective, research projects target groups of miners at risk due to specific patterns of work, equipment, mine settings and the management of safety and health in their mines. Incidence rates are provided by the MSHA data for selected variables, such as surface/underground location, standard industrial classification and state. While incidence rates are the preferred measure for all variables, denominators are not typically available; for example, to more clearly understand the data about injury by occupational type, it would be necessary to conduct demographic surveys. A current survey of the demographics of the mining industry should be complete by 2010, which will allow incidence rates to be developed for a number of variables such as age, occupation and experience. This survey will provide the first update of its kind since the first survey was conducted in 1985. This report describes an alternative method of analyzing and presenting MSHA data for the purpose of identifying high-cost, high-severity injuries and illnesses. Researchers at the NIOSH Spokane Research Laboratory (SRL) developed programs to find the top five most frequent accident classes, natures of injury, types of accidents and other selected variables from the MSHA database. Studying these variables gives a cross-sectional snapshot of the most frequent groups of injuries within a commodity, regional group or time period, and allows researchers to quickly understand developing patterns for new research projects. The primary benefit of this approach is to

Jan 1, 2009

By W. H. Strickland

The research reported here characterizes ultrasonic ranging sensors for autonomous navigation on underground mine mobile equipment. Because ultrasonic rangers are inexpensive, have no moving parts, have no lenses to clean, are small and unobtrusive, and can measure distances in dusty environments, they are especially sui ted to underground mi ne environments. The investigation began with laboratory tests of field of view, angle of incidence, intersensor variation, and ranging accuracy of individual rangers and a ring array of 24 sensors. The results showed the sensors have good accuracy and low variability. Additional experiments at AHAX' s Henderson mine Showed the sensors could accurately and reliably measure rib features, convex and concave corners, and drift intersections. The results showed that when used and analyzed properly, the sensor data may be used reliably for underground mobile equipment navigation.

Jan 1, 1990

By Yun-Jie Wei

Seismic areas were in the eastern margin of the Qinghai-Tibet plain, whose structures were complicated, mainly composed of Maowen fault, Yingxiu fault and Pengxian-guanxian fault. The rapid rise of the Qinghai-Tibet plain led the crustal material of the eastern edge to move to the southeast along the faults on a large scale since the late Cenozoic; Minshan block structure and Long Men Mountain tectonic zone represented the strong nappe thrust movement as the east boundary of Chuanqing slip block; the stress was accumulating when squeezed, which to a certain extent resulted in breakdown of the crust, and earthquakes. The shock speed, high-energy accumulation, and the reversed dextrorotation of the earthquake fault characteristics et al. happened, which caused the development of secondary geological disastersts. According to on-site investigation, the typical geological disasters had thrust rock collapse, the instability deposit, the revival of potential debris flow et al. whose genetic model had been analysed.

May 1, 2009

By Britt H. Hatfield, Jiu-Chiuan Chen, Wen-Ruey Chang, David C. Christiani

Occupational exposures to whole-body vibration (WBV) at different frequency domains may differentially affect human comfort and the musculoskeletal system. Under this presumption, a frequency-based weighting scheme has been adapted in many widely accepted standards for WBV measurement. However, there is very little human data showing a direct link between WBV frequency and musculoskeletal disorders. We conducted an epidemiologic study to examine the association between WBV frequency and prevalence of low back pain (LBP) and to identify determinants of specific frequencies associated with LBP in urban taxi drivers. Methods The WBV frequency data were collected from 247 professional drivers (aged 44.6±8.3) who participated in an exposure validation study 1 of the Taxi Drivers’ Health Study (TDHS) in 2000. 2 In accordance with the ISO 2631-1 (1997) methods, we measured the frequency-weighted acceleration over drivers’ seat surface, under conditions representing randomly assigned destinations. We developed a WBV record-replay system at the Liberty Mutual Research Institute (LMRI) in Hopkinton, MA, USA. This system includes two tri-axial accelerometers (PCB Piezotronics, NY, USA), one RD-130T PCM data recorder (TEAC, Tokyo, Japan), and one LMWBV meter 2.0 (LMRI, MA, USA). Only the vertical axis of seat-surface WBV frequency was used in this study. To characterize the WBV frequency curve, we manually identified the presence of any peak within each of the following frequency range: <4, 4-10, 10-20, and >20 Hz. Information about the operating vehicles and driving environment was either collected from the vehicle registration record (manufacturer, year of make, transmission, engine size, etc.) or directly measured (wheel-base length, seat inclination, etc.). Structured interviews were conducted by an occupational physician to gather information on LBP that had led to medical attention or absence from driving in past year. We used multiple logistic regression to estimate the prevalence odds ratio (OR) associated with the presence of each index peak frequency, adjusting for age, body mass index, professional seniority, daily driving hours, seat inclination, and the intensity of predicted root-mean-square WBV exposure in m/sec2. For any revealed WBV frequency that was associated with LBP, we constructed a multiple logistic regression model to identify the personal and vehicle characteristics associated with the presence of WBV peak within the indicated frequency range.

Jan 6, 2006

By Bowen Li, Canhua Li, Mingsheng He

Steelmaking slag is a by-product in considerable volume and a valuable material for various applications. In general, steelmaking slag is an alkaline compound of CaO, Fe2O3, and SiO2. However, its characteristics varies depending on the feedstocks, steelmaking process and cooling method of the slag. To utilize this by-product effectively, this study investigated the characteristics of steelmaking slags taken from Wuhan Iron & Steel Co. Ltd. The results showed that the slags mainly consist of the oxides of calcium, iron, and silicon, with low contents of magnesia, alumina, and manganese oxide with a feature of high alkalinity and lime saturation factor. The major mineral phases include belite, calcium ferrite, calcium hydroxide, wustite, quartz, and small amount of elite. Thermogravimetric analysis indicated the weight loss from ambient temperature to 800 °C is 8% in total. Melting test showed the glass transition temperature is between 1300 and 1350 °C, flow temperature is about 1400 °C. The slag samples investigated in this study can be considered as a typical glass-ceramic composite.

Mar 1, 2018