Abstract: Although only used in a few U.S. longwall mines, bleederless ventilation systems can be an effective spontaneous combustion control method in mines having a demon­ strated history of spontaneous combustion. To provide insights for the optimization of bleederless ventilation systems for U.S. underground coal mines, a computational fluid dynamics (CFD) study was conducted to model the spontaneous heating in longwall gob areas using a bleed­ erless ventilation system. A single longwall panel with a bleederless ventilation system was simulated, and typical longwall mine ventilation data were used in the simulations. The permeability and porosity profiles for the longwall gob were estimated using a geotechnical model and were used as inputs for the CFD modeling. The effects of gob permeability and resistance of the collapsed entries on the spontaneous heating were studied. The effectiveness of using nitrogen injection to prevent spontaneous heating in the gob was also examined.1 tion in underground coal mines. Be­ cause of the difficulty in conducting full-scale spontaneous combustion tests in underground coal mines, computational fluid dynamics (CFD) model­ ing has become an important method to study the spon­ taneous combustion in underground coal mines. Saghafi and coworkers did numerical modeling of spontaneous combustion in underground coal mines with a back return U-ventilation system (Saghafi et al., 1995; Saghafi and Car­ ras, 1997), but their work was limited to two dimensions. Balusu et al. (2002) conducted a CFD study of gob gas flow mechanics to develop gas and spontaneous combus­ tion control strategies for a highly gassy mine. Rosema et al. (2001) also simulated spontaneous combustion using a two-dimensional model. To understand the fire hazard caused by spontaneous combustion in a gob area, a computational fl uid dynamics (CFD) study was carried out by the National Institute for Occupational Safety and Health (NIOSH) to model the spontaneous heating in longwall gob areas under realistic mine ventilation conditions and methane generation rates. In previous NIOSH research, a CFD model was developed to describe the ventilation pathways through the immedi­ ate gob under different ventilation schemes (Yuan et al., 2006) and to simulate the spontaneous heating of coals in a two-panel gob area using a bleeder ventilation system (Yuan and Smith, 2007). In this paper, the CFD model was used to study the spontaneous heating of coals in a longwall gob area utilizing a bleederless ventilation system. Gob layout and ventilation system In a bleederless ventilation system, the previously mined-out panels are usually isolated from the active gob and the remainder of the mine. In this study, only the ac­ tive panel was simulated. The layout of the panel and the ventilation system is shown in Fig. 1. The simulated gob area is 2,000 m (6,562 ft) long, 300 m (984 ft) wide and 10 m (33 ft) high starting from the bottom of the coal seam. The ventilation airways are 2 m (6.6 ft) high and 5 m (16.4 ft) wide. The ventilation scheme is a simple “U” bleederless ventilation system. In the model, all entries inby the longwall face were treated as though they were collapsed. FIGURE 1 Typical ventilation pressures for the bleederless ventilation system Layout of longwall panel and ventilation system. were used in the simulation. The pres­ sure was -76.2 mm (-3 in.) water gauge at the intake inlet and -88.9 mm (-3.5 in.) water gauge at the return outlet. To control the airflow quantity to the longwall face, the wall roughness was adjusted to have a realistic intake airNumerical modeling A commercial CFD program, FLUENT2, from Fluent Inc., was used in this study to simulate the gas fl ow and spontaneous heating in the longwall gob areas. The gas flow in the longwall gob area was treated as laminar fl ow in a porous media using Darcy’s law, while the gas fl ow in the ventilation airways was simulated as fully developed turbulent fl ow. The permeability and porosity distributions of the gob area were based on geotechnical modeling of longwall min­ ing in the Pittsburgh coal seam and the associated stressstrain changes using Fast Lagrangian Analysis of Continua (FLAC)) code (Esterhuizen and Karacan, 2005). For a Pittsburgh coal seam longwall panel, the permeability val­ ues in the gob area were estimated to vary from 3.0 x 104 to 8.5 x 105 millidarcies (md), while the porosity value varies from 0.17 to 0.41 based on the modeling result from FLAC. Around the perimeter of the gob and immediately behind the face shields, the permeability and porosity values were the largest, while near the center of the gob, these values were the smallest due to compaction. A detailed descrip­ tion of the permeability calculation is given in Esterhuizen and Karacan (2007). The porosity profile in the gob was similar to the permeability profile except the maximum and minimum values are 0.41 and 0.17, respectively. It is assumed that these permeability and porosity fi les do not change with the gob height.The detailed permeability pro­ files are presented in Yuan and Smith (2007).

Abstract: In underground mines, coal dust explosions are prevented by the addition of rock dust sufficient to render the coal dust inert. The National Institute for Occupational Safety and Health (NIOSH) has developed a hand-held instrument that uses optical reflectance to measure the explosibility of a rock dust and coal dust mixture. This instrument is called the Coal Dust Explosibility Meter (CDEM). In this study, NIOSH personnel accompanied Mine Safety and Health Administration (MSHA) inspectors on their routine band surveys in five and three underground coal mines in MSHA District 2 (PA) and District 11 (AL), respectively. While underground, NIOSH personnel and MSHA inspectors used the CDEM to assess the explosibilities of the dust samples. The values of percent incombustible content (% IC) determined by the CDEM agreed well with those obtained later by low temperature ashing (LTA) in both MSHA and NIOSH laboratories. Further, the meter identified some samples as potentially explosible that LTA analysis had found to possess sufficient rock dust for inerting. The CDEM provides more information on the hazards in the mine. Rapid identification of areas with explosible dust mixtures using the CDEM allows for immediate intervention rather than a wait of several weeks for laboratory analysis.

Abstract: National Institute for Occupational Safety and Health (NIOSH) researchers conducted an investigation to quan­ tify sound levels and to determine the amount of sound reduction provided by engineering noise controls installed in a talc processing plant. Baseline sound level and sound intensity measurements were performed at the plant, and the measurement locations were recorded for comparison to post-control measurements. Follow-up measurements were then made at the same locations after the initial noise controls were installed. The plant subsequently decided to implement additional noise controls and the researchers returned to conduct measurements for a final analysis of all noise controls. The most significant results showed a sound level reduction in the main mill area from a range of 93 to 104 dB(A) down to a range of 90 to 94 dB(A) and a total sound power level reduction of 21 dB(A) for air classifying Mill 3. Introduction In 2003, more than 12,000 nonmetal employees worked in preparation or mill plants (NIOSH, 2003). A NIOSH study revealed that by age 50, approximately 49% of metal/nonmetal miners have a material hearing impairment (NIOSH, 2007). Accord­ ingly, there is potential for almost 6,000 nonmetal processing plant workers to be hearing impaired by age 50. This study’s noise control work will be useful for the approximately 150 U.S. nonmetal-processing plants (MSHA, 2005) to help them reduce the sound levels of their mills. With the cooperation of mine officials at a talc pro­ cessing plant, NIOSH conducted a study to quantify inplant sound levels and to determine the amount of sound reduction provided by engineering noise controls installed by mine personnel. The long-term goals of the mine of­ ficials were to reduce in-plant sound levels and worker noise exposure. The noise control evaluation at the talc processing plant was performed as part of NIOSH’s effort to locate and evaluate state-of-the-art engineering noise controls. In addition to locating and assessing existing controls, NIOSH is also identifying processes or machines in need of noise controls, gaps in technology that impede the use of noise controls and barriers to the use of noise controls, including collateral hazards (NIOSH, 1996). The specific noise controls for this study — acoustic curtains and sound barrier and sound absorber materi­ als — as well as the theoretical concepts can be applied not only to talc plants but also to other comparable machinery in all industrial sectors. The noise control retrofi t treatments for mining machinery can be found in the Bureau of Mines handbook titled Mining Machinery Noise Con­ trol Guidelines (Bartholomae and Parker, 1983).There is a high level of consensus about the theory, appropriate principles and evaluation methods for engineering noise controls (Bies and Hansen, 1987; Lord, 1988; Driscoll, 1996; Harris, 1998). This study applied the consensus noise control approach by identifying and quantifying noise sources, developing appropriate engineering and administrative controls, and quantifying the extent of noise reduction attributable to each control intervention alone and in combination. To identify noise sources and their relative impor­ tance, baseline sound level and sound intensity measure­ ments were performed with equipment turned on or off in a pre-selected process.The sound levels and their mea­ surement locations were then entered into SSG-SurferTM software1 1 Reference to specific brand names does not imply endorse­ ment by the National Institute for Occupational Safety and Health. to produce sound level contour mappings of the mill floor area.Temporary and fixed acoustic curtains and sound absorption material were then used, and postcontrol sound level and sound intensity measurements were taken to further identify the noise sources.After ad­ ditional engineering noise controls were installed, sound level and sound intensity measurements were taken to quantify the post-control noise levels and the effec­ tiveness of the controls. For this study, the sound level measurement was averaged for at least 12 seconds (time determined by researcher using B&K and American Na­ tional Standards Institute [ANSI] recommendations) at each location (American National Standards Institute, 2001). Figure 1 is a top view of the main mill area show­ ing each numbered measurement location. During these measurements, the Bruel & Kjaer1 (B&K) 2260 Investi­ gatorTM was mounted on a tripod such that the measure­ ment microphone was 1.43 m (56 in.) above the floor (International Organization for Standardization, 1987). The work patterns and employee locations in this fa­ cility fluctuated unpredictably, depending on events that occurred during talc processing. In most cases, employees would be moving in and out of the noisiest areas, and their exposures would probably be very low. However, the mine offi cials felt that unusual situations could arise where workers would spend prolonged periods of time in the noisy areas. These situations were too unpredictable to be captured reliably through standard full-shift dosim­ etry. Instead, the scope of the current study was limited to reducing noise sources with the expectation that dose reductions could be verified later, if necessary. Sound level measurements Sound level measurements were conducted at 47 loca­ tions, approximately 2 m (79 in.) apart, on the processing plant floor under full operating conditions both with and without noise controls installed. A spot marking each measurement location was painted on the concrete fl oor to make the repeated measurements as consistent as pos­ sible. At every measurement location, the A-weighted equivalent continuous sound pressure level (LAeq) spec­ trum was measured using a B&K 2260 InvestigatorTM running Enhanced Sound Analysis software. The refer­ ence used when dealing with sound pressure is 2 x 10-5 Pascals (Pa), which is the sound pressure that is barely audible at 1,000 Hz.When measured, this sound pressure would yield a value of 0 dB.The term “level” is commonly used to designate a logarithmic ratio of relevant param­ eters. Therefore, a sound pressure equal to the reference pressure of 2 x 10-5 Pa (1 Pascal = 1.45 x 10-4 pounds per square inch) produces a sound pressure level (SPL) of 0 dB. To quantify the change in pressure at any point due to a passing sound wave, the root-mean-square (RMS) value is used. The SPL for any sound can be calculated

Abstract: From 2001 to 2007, the Pittsburgh Research Laboratory (PRL) of the National Institute for Occupational Safety and Health (NIOSH) conducted studies to develop alternative methodologies to full-scale explosion testing for deter­ mining the ultimate strength of mine seals. As a result, the PRL developed and proposes an alternative seal-strength evaluation method based on a hydrostatic pressure-loading concept. The researchers suggest pressure loading a seal using water to twice the expected dynamic design load.The hydrostatic chamber test offers a means of validating seal designs, establishing appropriate resistance functions and determining the ultimate strength of seals through testing to failure.This article contrasts the full-scale explosion and hydrostatic testing of mine seals using a simple dynamic system model and principles. Introduction Tragic mining disasters in West Virginia (Sago Mine) and Kentucky (Darby Mine) in 2006 greatly heightened interest in the development of quality seals to protect miners from blast effects and toxic gases produced by uncontained gob explosions. Following the enactment of the 2006 Miner Act and the U.S. Mine Safety and Health Administration (MSHA) issuance of the Emergency Tempo­ rary Standard (ETS) on the Sealing of Abandoned Areas in 2007, MSHA is conducting de­ tailed technical evaluations of all proposed seal designs for each underground sealing location. These technical evaluations are based on sound structural engineering design approaches followed by certification of as-built construction. MSHA will also accept the results from full-scale testing of mine seals. If full-scale performance testing is required to develop seal stress-strain response data, the authors propose a hydrostatic test method as an alternative to full-scale explosion testing.This method uses water to load the seal to pressures at least twice the expected dynamic design load to determine stress-strain data. This article contrasts the full-scale explosion and hydrostatic testing of mine seals using a simple dynamic system model and principles. There are many three-dimensional, finite-element codes for designing various load-bearing structures that can simulate not only the seal itself, but also the interac­ tion of the seal with the surrounding support strata. How­ ever, when studying a single mode of seal response, the basic analytical model used in most blast-design applica­ tions is the single-degree-of-freedom (SDOF) system. In the current study, the U.S. Army’s Wall Analysis Code (WAC) (Slawson, 1995) was used to identify test conditions where hydrostatic pressure loading can serve as an alternative yet equivalent test method to full-scale methane-air explosions for evaluating the strength performance of mine ventilation seals. Such hydrostatic tests would build confidence in design methodology through comparisons be­ tween pretest predictions and actual measurements, as well as provide a timely, cost-effective means of seal testing. Single-degree-of-freedom system (SDOF) All structures possess more than one degree of free­ dom regardless of how simple their construction. How­ ever, many structures can be adequately represented as a SDOF system for purposes of analysis.The accuracy of an SDOF approximation depends on how well the deformed shape of the structure and its resistance can be represent­ ed with respect to time. The procedure for obtaining the equivalent SDOF approximation for a structural compo­ nent is based on its deformed shape under the applied loading and the strain energy equivalence between the actual structure and the SDOF approximation. Equivalent mass, stiffness and loading are obtained through the use of transformation factors. Chapter 3 of the U.S. Department of Army, the Navy and the Air Force design manual TM 5-1300 (1990) contains tabulated transformation factors for typical structural elements, including slabs. The derivations of the equations for the transformation factors are also given in this reference and used in the WAC. The WAC is an SDOF model developed for the U.S. Army Engineer Waterways Experiment Station (WES), Structures Laboratory (Slawson, 1995). WAC was de­ veloped to provide a tool for the easy calculation of the response of typical walls subjected to blast loads. The WAC can calculate the resistance function (R(y), pres­ sure-deflection) of a wall given its construction details, including dimensions, material properties and support conditions or accepts user defined resistance functions based on experimental data. The WAC transforms the wall model to an equivalent SDOF model, calculates the actual and SDOF equivalent loads and solves the equa­ tion of motion to determine the response time history of a central point on the wall. The equation of motion for an SDOF system is M·yʺ(t) + Cd·yʹ(t) + R(y(t)) = F(t) (1) where M is the equivalent or “lumped” mass of the system; Cd is the damping coefficient taken as 5 percent of the critical value, i.e. very lightly damped; y(t) is the placement of the mass as a function of time t; yʹ(t) is the velocity of the mass or first derivative dis­ placement; yʺ(t) is the velocity of the mass or second derivative displacement; R is the structural resistance as a function of displace­ ment y; and F(t) is the structural load as a function of time, i.e. expected blast pressure history.

Abstract: Pillars in underground limestone mines are required to support the overburden and provide a safe, stable working environment for mining personnel and equipment. Pillar stability was assessed by the National Institute for Occupa­ tional Safety and Health in underground limestone mines in the Eastern and Midwestern United States. It was found that current mine layouts have been successful in providing support to the overburden, while a small number of isolated pillar failures were observed. The stable pillar layouts and failed pillars were plotted on a chart that demonstrates the relationship between pillar width-to-height ratio and pil­ lar stress. The results show that pillar failures occurred at the lower range of width-to-height ratios and can occur at relatively low stress levels. Zones indicating the potential risk of pillar instability are shown on the chart, based on hazards associated with the onset of rib spalling, large angular discontinuities and unconfined pillars. The chart can assist limestone mine planners to evaluate potential instability in current or new pillar layouts that are similar to those included on the stability chart. pillar conditions (Bauer et al., 2005). Newly designed or current pillar layouts can be compared to the current experience by plotting them on the chart. An example is given in which a typical pillar layout is assessed using the chart data. Observations of pillar stability Pillars were assessed at underground limestone mines located in Illinois, Indiana, Iowa, Kentucky, Maryland, Missouri, Ohio, Pennsyl vania, Tennessee and West Virginia. The pillar stability was evaluated at more than one location at each mine to capture the variety of geological and mining conditions. Two criteria were used to assess the success of the pillars. The first criterion is the requirement for regional stability, which is defined as the need for a pillar system to success fully support the overburden. If a pillar system fails in providing regional support, a wide area collapse is likely to occur with associated surface subsidence. The second criterion is the requirement for local pillar stability, de fined as stable pillar ribs. Rib conditions were assessed by noting the presence of rib spalling, stress fractures or open cracks. The presence of geological features such as joints, slips, faults and weak bedding planes was also recorded. Where unstable conditions or failed pillars were ob served, the likely factors contributing to pillar instability were noted. In addition, pillar and room dimensions were measured and information on the depth of cover, extent of floor benching and other mining parameters collected. Mine maps were obtained so that the pillar loads could be calculated using the tributary area method or numeri­ cal models. Rock samples were collected to determine the uni axial compressive strength (UCS) of the rocks. The UCS results were grouped into three categories based on the average strength obtained at the individual mine sites and are shown in Table 1. It can be seen that there is a considerable variation in the strength of the limestone being mined. This variation in strength was accounted for in the assessment of pillar stability. Table 2 summarizes the dimensions and cover depth of the pillar layouts that were investigated. The results of the survey showed that all the mine sites visited were successful in terms of the criterion for regional stability. No case of wide area collapse or signs of large areas of overloaded pillars were observed. Howev­ er, a number of isolated failed pillars in otherwise stable layouts were observed. These isolated failed pillars are

Abstract: According to actual condition of Caolou Iron Ore Mine and with regard to technology level,refill capability quality,refill cost economic benefit,the advantaged and disadvantages of refill technology with classified tailings and unclassified tailings are explained.

Abstract: A research was carried out on the sulfur recovery from sphalerite in oxygen pressure acid leaching slag in leaching wayIt chooses PCE as organic solution and finds out the rule of the effection of temperature,liquid-solid ratio,time and the return rate of organic solution,organic additives on sulfur recovery

Abstract: The flotation test of potash feldspar and soda feldspar from a mine in Shandong province is introduced,and the mechanism of flotation is analyzedIt is possible to obtain qualified feldspar concentrates and quartz concentrates using HF method and rough concentrate re-grinding re-separation

Abstract: After long-term mining,a lot of open pit mines have to turn into underground mines.The first difficulty for such mines is mining of pit wall-connected ore body.The properties of mining of such ore body,system of development and selection of mining methods are discussed.

Abstract: Iron-rich hydrargillite's samples from deferent countries are treated by Bayer process at 143℃ and 245℃.Samples are characterized with XRD、DTA-TG、IR.Forming process of Hematite and Goethite are discussed.The results indicates that ferrous mineral's digestion performance are different,and sedimentation of red mud is greatly affected.

Abstract: Apply owing to that Return Method application in the mine technology index optimization.The article take the Jiaojia gold mine builds process as example,brief have introduced that the method how to make use of return builds mathematic model.Result that under the current technology and technological level,build the rational technology index model by regression analysis can make that company gain the much better economic effect,save mineral resources at the same time.

Abstract: According to the function of Surfer software,this paper introduces it that is been used in mining subsidence visualization.Surfer software can be used in mining subsidence data processing,visualizing the result of mining subsidence data processing and doing some spatial analysis based on the result of mining subsidence visualization.Through some practice,we find that Surfer software is good at visualizing mining subsidence data and doing some spatial analysis about mining subsidence.

Abstract: Under the theories and the methods of the comprehensive information metallogenic prognosis,applies the MapGIS which have a lot of formidable function include the data bank and the map editing as well as the spatial function which is comprising with analysis,inquiry and searches to carry on the reorganization and the synthetic analysis the data of the geology,the remote sensing,the geophysical prospecting and the geochemical exploration.After this,we could search for minerals target in the highly effective,fast and economically way.

Abstract: Wet-type dust removal fan applied in mechanical coal cutting stope is explained.The performance of the fan is inspected and analyzed.According to actual conditions of stope,reasonable parameters for fan's erection application are determined thus good dust removal effect is achieved.

Abstract: Rock failure process analysis(RFPA~(2D))system was employed to simulate the destruction of rectangular road.The distribution of stress,occurrence of cracks and final failure model were numerated and analyzed by RFPA~(2D) and failure regularity of rectangle road in some representative type of surrounding rockmass was obtained.This result indicated the failure result of rectangle road is different from other shape road because of the relation of the shape and surrounding buildup configuration.

Abstract: The pre-dearsenication technology for gold ore with high arsenic content is recently a hot spot of research.It is of great importance for increasing leach rate of gold,improving leaching process,developing new gold extraction technology and realizing effective recovering of gold.The progresses in pre-dearsenication technology for gold ore with high arsenic content,and the researches in roasting type,wet type and bacteria type oxidation of high arsenic gold ore are explained in brief.Besides,the future of research work is prospected.

Abstract: Based on the slice method of Janbu,in which the failure surfaces is arbitrary-shaped,and the reliability theory of JC,a function equation in limiting equilibrium is developed to calculate factors of safety of slopes.According to the influence to the slope,the soil parameters,including coherence c and internal friction angle φ,are regarded as random variables,and the coherence c which is not normally distributed is normalized.Using the random field theory,the influence of the correlation of shear strength to the reliability index is analysized.

Abstract: In this paper,the importance of dephosphorization process in treatment of high-phosphorus iron oreThe characteristics of the technological mineralogy of the iron ore,occurrence station and dissemination characteristics of phosphorous are describedBy the research,the dephosphorizing process of low intensity magnetic-high intensity magnetic shacking table separation is selected

Abstract: The recent status,trend and research development of converter slag utilization technology in Anshan Iron Steel Groups Corporation are explained.In addition,some important issues in relation to research work in the future are pointed out.

Abstract: Based on measured slope shift data and analysis of features of monitoring curve,the inherent programming language VBA of AutoCAD is used to develop a data-into-graph conversion program that realizes the automatic drawing of slope shift monitoring curve.The application of the program in western Pingzhuang Open-pit Mine increases the efficiency of slope shift monitoring work thus is referential for similar project.

Abstract: Rough control is such a method that acquires control rules according to the data observed.The results of data preprocessing in rough control,therefore,is vital to the final produced control rules.Methods applied in data preprocessing are discussed in this paper.At the same time,some improvements of these methods are proposed,and especially a new algorithm to get rid of the inconsistent data is put forward.These methods have been applied in the rough control of cation anti-floatation in Gongchangling,receiving remarkable effect.

Abstract: The status of development of digitalization informatization in domestic foreign mines is introducedMain progresses existent problems of development of digitalization informatization in Chinese mines are summarizedOn these bases,essential working points and research directions in the future are pointed out