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By Richard E. Ray, George N. Aul, Fred Garcia, William P. Diamond

Increasing longwall panel dimensions, particularly face width in gassy coalbeds, may result in unexpected increases in methane emissions. To investigate this problem, continuous longwall face emission monitoring studies were conducted at two adjacent mines operating in the Pocahontas No. 3 Coalbed, where longwall faces were to be extended from 229 to 305 m (750 to 1,000 ft). It was predicted by regression analysis of methane emissions data from 229 m (750 ft) wide longwall faces that extending faces to 305 m (1,000 ft) would increase methane emission rates by only 7 percent (0.6 m3/min (20 cfm)), to 8.6 m3/min (304 cfm) at the VP-1 Mine. In contrast, it was predicted that extending faces at the VP-3 Mine could increase methane emissions by as much as 13 percent (1.8 m3/min (65 cfm)) to 16.1 m3/min (567 cfm). The geologic and mine design factors influencing the variation in face emissions between the two mines will be discussed.

By B. Galy, L. Giraud

"This paper compares Canadian provincial mining safety regulations regarding the use and testing of cage safety catches, including a brief history and evolution. Regulations are similar across provinces, with only slight variations. Currently, the “Ontario-type” safety dog is the most commonly used safety catch in Canada. Performance estimation of the compensation mechanism for different safety-dog shapes and tooth angles show this shape works well and has consistent braking results, but the best efficiency is obtained for initial tooth angles greater than 10°. Miner safety is questionable for lightly loaded cages, an issue that should be addressed technically and legislatively.RÉSUMÉ Le présent article compare les diverses réglementations de sécurité minière concernant les parachutes des cages dans les provinces canadiennes ainsi que les essais qu’ils doivent subir. Il semble que les réglementations soient semblables à travers les provinces avec quelques légères différences ou divergences. Un bref historique des parachutes et de leur évolution est présenté. De nos jours, le parachute de « type Ontario » est le plus fréquemment employé à travers le Canada et il présente des résultats de freinage uniformes. Une estimation de la performance du mécanisme de compensation pour les diverses formes de taquets de sécurité et les divers angles des dents montre que cette géométrie fonctionne bien; cependant, la meilleure efficacité est obtenue pour des angles de dents supérieurs à 10°. La sécurité des mineurs est mise en jeu pour des cages faiblement chargées et ce point devrait être traité du point de vue technique et du point de vue législatif."

Jan 1, 2016

By Edwin F. Shorey, Richard F. Coon, Steven B. Fradkin

Crosstown Interceptor Phase IA is the first deep tunnel element of the Milwaukee Inline Project. The tunnel contract includes 6,492 meters (m) of 9.1-m-diameter tunnel, two access shafts, and partial lining for structural purposes. The work also includes grouting to be performed as directed by the engineer to provide groundwater infiltration control in lined and unlined reaches of the tunnel. This paper summarizes infiltration observations, progress of the grouting work, and its potential application to the remainder of the Milwaukee project.

Jan 1, 1987

By Drew Floyd

Five full-scale pile load tests were performed on pairs of PZ-22 sheet piles installed with a vibratory pile driving hammer. The sheet piling was installed in several locations in soil generally consisting of miscellaneous granular fills overlying soft organic silts, inorganic silt interbedded with sands and gravels, very dense glacial till and shale bedrock. The test program also included the use of tip tell tales to determine what capacity could be attributed to tip resistance and skin friction. During the design phase of the project, it was assumed that the capacity of the sheet piles driven with the vibratory hammer could be correlated with the rate of penetration. The correlation between vertical capacity and rate of penetration would be used as a basis for determination of a driving criteria from driving the production sheet piling. The sheet piling load tests demonstrated that it was not possible to correlate the capacity of sheet piling driven with a vibratory hammer and the rate of penetration. It was also demonstrated that the capacity of the sheet piles was directly related to the density of the soil at or just below the tip. The results also tend to agree with empirical equations provided by Meyerhof (1976).

Jan 1, 1989

By Emilio Giuseppe Sarno Severi

Mining and Petroleum Similar Industries ?Asset Intensive ?Exposed to market volatility ?Highly Risky Operations ?Scarcity of Experienced and Trained resources ?Operating in diverse countries with different cultures ?Increasing Environmental and Safety Regulations

Nov 1, 2011

By H. O. Ghaffari

A complex network approach on a rough fracture is developed. In this manner, some hidden metric spaces (similarity measurements) between apertures profiles are set up and a general evolutionary network in two directions (in parallel and perpendicular to the shear direction) is constructed. Also, an algorithm (COmplex Networks on Apertures: CONA) is proposed in which evolving of a network is accomplished using preferential detachments and attachments of edges (based on a competition and game manner) while the number of nodes is fixed. Also, evolving of clustering coefficients and number of edges display similar patterns as well as are appeared in shear stress, hydraulic conductivity and dilation changes, which can be engaged to estimate shear strength distribution of asperities.

May 1, 2009

By André Pomerleau, Michel Grégoire, René del Villar

"The operation of industrial flotation columns requires the control of at least two variables, the interface position and the bias rate, by manipulation of some appropriate operating variables. Problems arise due to the reliability of existing methods of measuring the bias (i.e bias = tailings water - feed water), a situation which has often forced the industry to disregard this control loop. Moreover, when using such a measuring approach, the identification of the process dynamics is impossible. A second problem arises from the possible interaction between both control loops that might call for the use of a more complex multivariable control strategy.Recent work done at Lava1 University has demonstrated the feasibility of an independent sensor for bias, which models the relation between the conductivity profile across the interface and the bias value using a neural network algorithm. A 250 cm height, 5.25 cm diameter Plexiglas laboratory column was equipped with a series of conductivity electrodes in its uppermost part (across the interface) to measure both interface position and bias rate. Using such equipment, the flotation column dynamics were identified. The results thus obtained permitted the design and implementation of a distributed PI control strategy, where bias was associated to wash water rate and froth depth to tails rate. Both PI controllers were tuned using a frequency-response tuning method. Results of both identification and process control are presented and discussed.INTRODUCTIONFlotation columns are used for the separation of valuable minerals from a carrier gangue. Typically, this device is a tall (9 to 14 m height) cylinder (1 to 3 m in diameter) although other cross sectional shapes are also used. Finely ground ore is fed as a pulp at about 2 m from the top of the column, and pressurized air is introduced through a sparger at the bottom. If the pulp has been properly conditioned with adequate chemical reagents (collectors and modifiers), the valuable mineral particles falling by gravity will attach themselves to the rising air bubbles, and the air-particle aggregates will rise to the top of the column where they overflow as a stream called the concentrate. The gangue particles,, that do not attach to the air bubbles, fall down the column being withdrawn at its bottom in a stream called the tails.A particular characteristic of flotation columns is the addition of a fine spray of water at the top. As the water flows down through the froth zone, it washes out the entrained gangue particles from the mineralized bubbles, thus improving the quality of the concentrate recovered at the top. As a result of its cleaning action, this water stream is called the wash water and the upper zone, the cleaning zone. In order to ensure a downward flow of wash water, a proper water balance must be kept in the froth zone, otherwise the water added at the top might shortcircuit to the concentrate without performing any cleaning action. This net downward flow of water inside the froth zone is called the bias and represents an important operating variable of a flotation column."

Jan 1, 1999

By Jom Gentry

Acrylamide chemical grout (C3H2NO) has been successfully used for over 50 years to control groundwater and stop infiltration. This paper will address three unique projects involving the control of groundwater with each study providing special circumstances and geological conditions: encapsulation of radioactive hazardous waste in the United States, a tailings dam for a large copper/gold mine in Argentina and 27 miles of leaking subway in Canada. The primary reasons for selecting acrylamide grout were based on the following characteristics: thinnest chemical grout on the market, a true solution grout which contains no suspended solids in the blended product, flexible gel set times, and a 362 year half-life in soil as determined by the U.S. Department of Energy.

By D. F. Lascelles

D. F. Lascelles (School of Earth Sciences, MacQuarie University, North Ryde, N. S. W., Australia)- The paper contains many misconceptions commonly held by both geologists and soil scientists with regard to soil processes. The analogy between supergene copper enrichment and "nickel laterite" deposits is quite apt and the use of nomenclature from the former in describing supergene nickel deposits is justified. However, care must be exercised with regard to the notable differences in

Jan 1, 1974

The International Symposium-cum-Workshop on Management andControl of High Gas Emissions and Outbursts in Underground CoalMines was held in Wollongong in March 1995. Coverage of high gasemissions was virtually confined to instantaneous outburst implications, essentially seam gas pre-drainage. Globally, instantaneous outbursts have been known for 150 years, andthe first Australian outburst occurred in 1895 and Australian occurrences and mines affected have increased since. Few significant coal producing countries are unaffected. The coals affected range in rank from lignites to anthracites. Geological disturbances are the most likely environments for occurrences. The most likely mining geometry is of virgin headings, with some occurrences on longwalls and in other situations. Widespread research into many aspects of the problem has yet to produce a generally accepted explanation. Explosive inducement is a well-known control. Apparently high advance rates increase face gassiness and create higher stress abutments, increasing proneness. The most popular preventive measure, pre-drainage of virgin coal ahead of faces has produced highly successful very long hole drilling performances but without the precision necessary for accurate geometric hole patterns, despite quite sophisticated drilling equipment and hole surveying instruments. For the future, more precise degasification is sought, even from the surface, together with rapid face coal gassiness assessments to confirm lowering below threshold values, as well as other proneness lowering measures, perhaps related to new heading and longwall geometries and to new equipment to provide them. But above all, safe management plans are required for each operation, to safeguard the miners and their working environments, and thus to protect underground coal mining from this mounting threatening problem.

Jan 1, 1997

By S. Garcia, J. Gebhardt, D. McBride, A. Hernandez, A. Esplín, M. Cross

The Minera Yanacocha operation consists of several heaps interconnected with ponds and gold recovery plants and presents various operating challenges. A comprehensive process model has been developed in order to better understand the effects of certain operating parameters and inventory issues. An integral component of the process water/mass balance is a model of each heap that describes heap behavior based on the individual characteristics of the heap. The heap models are linked to a mass balancing program in order to track flows and concentrations throughout the circuit. A case study of the process heap model is presented for the La Quinua heap, including results for the normal base line operation and several operational problems such as loss of solution flow to the heap (i.e., pump failure), increased flow to a section of the heap (i.e., pond volume control), effect of significant rain events, and impact of a change in material properties (i.e., change in ore type). The impact on heap operating efficiency is discussed with regard to effects on recovery and gold solution grades.

Jan 1, 2007

By E. H. Cho, B. Conner

Three sulfide minerals, chalcopyrite, sphalerite, and pyrite, were leached using a bioleaching mode and an electrobioleaching mode. The former mode was used to leach the minerals with the bacterium A. ferrooxidans in a bioreactor. In the latter mode, the leaching of the minerals was performed in a combination of a bioreactor and an electrochemical cell. In this set-up, the solution was circulated between the bioreactor and the cathode compartment, the two reactors were in series, and the cell was operated intermittently. The mechanism is such that an increase in Fe(II) concentration, which is a nutrient of the bacteria, by electrochemical reduction of Fe(III) would increase the bacterial population and in turn would accelerate the leaching of the mineral. It has been found that the electrobioleaching of chalcopyrite is an improvement over the bioleaching with respect to the fact that leaching conversion is higher and a high level of Fe(II) concentration can be maintained. However, the electrobioleaching of sphalerite does not show any improvement over bioleaching. The electrobioleaching of pyrite is similar to that of chalcopyrite, and this has potential to be used in applications such as coal desulfurization and pretreatment of refractory gold ore in heap leaching where fine gold particles are entrapped inside pyrite particles.

Jan 1, 2006

By Denis Thibodeau

his paper describes a study of an altered mining extraction and the resulting Rockmass response at VALE?s Creighton Mine. Typically, the deep mining zones have strict stope extraction guidelines to ensure safety and productivity; however, these guidelines offer low flexibility or few options for stope sequencing. The 402 O. B. being in a good rock mass, at moderate depth and stress regime at Creighton, offered an opportunity to drive a more flexible mining sequence with stopes and a pillar. A three-phased approach was used to mitigate risk of the mining plan: 1- Numerical modelling to fully anticipate rock mass response to the proposed mining sequences. 2- In situ seismic monitoring to collect stress and seismic activity data. 3- Analysis of the in situ data to correlate to the modelling results. The creation and the extraction of a pillar in the 402 O. B. was successfully completed. The recorded seismic activity agrees well with the numerical modelling since most of the seismic activity is localised in the hangingwall where the deviatoric stress corresponds to an early damage process. The moderate levels of deviatoric stress cause localised failure with low level of seismic activity.

May 1, 2013

Jan 1, 1967

By Thomas A. Bailey

Since the advent of longwall mining, various methods and materials have been used during relocation to control the intrusion of the gob in the shield/panline area. (figure 1) Controlling this gob is critical to ensuring a safe, speedy, and productive longwall move. An uncontrolled gob can cause a number of problems, from increased worker exposure to entrapment of equipment to lost production. With an eye toward worker safety and increased productivity, several different methods have been developed to minimize gob intrusion. This presentation will take a look at the history and development of longwall ?screens? and ?mesh?, from chain-link fencing to high-modulus polyester geogrids. The benefits and advantages of these developments will be defined. Since 1994, longwall coal mines have used polymer geogrids during longwall recovery to control intrusion of gob material into the shield/pan line area. As described by Brandon and Collins (1996) in their paper presented at the 15th Ground Control Conference in Golden, CO., mines had used various forms of support, such as welded wire mesh, chain-link fencing, wooden cribbing, props, and steel cable to accomplish this. These methods worked, but were labor-intensive, slow, and provided varying degrees of gob stoppage. Although a few mines still use chain-ink fencing to control the gob, longwall coal mines have generally settled on polyester geogrids to control gob and roof and these mines have been instrumental in providing input in order to develop and improve these geogrids products. he trend during the past twelve years has been to incorporate stronger grids and to eliminate auxiliary reinforcements, such as steel cables and nylon or polyester webbing. A job that once required heavy steel cables, props, and fencing is now accomplished with strong, lightweight, high-modulus polyester grids. When we discuss high-modulus grids, we refer to the ratio between load and strain, as illustrated in figure 2. These grids are woven or knitted from yarns that have been pre-stressed. When these grids come under load, they pick up the load more quickly. This allows less deformation in, in this case, the mine roof. The same principle applies when these grids are used to control the ribs. With less elongation, the grids will hold rib material tighter, thereby keeping travel ways more open.

Jan 1, 2006

By K. S. Seljesater

SINCE the development of dispersion-hardenable lead-antimony alloys1 in the laboratories of the Western Electric Co., Inc., studies have been made of the effect of various third constituents on these alloys.2 This paper covers a study of the effect of small amounts of arsenic. This element is important since it occurs as an impurity in many commercial antimonial leads and the results obtained are particularly interesting as indicating a class of addition agents which exert a stabilizing effect on dispersion-hardened alloys. EXPERIMENTAL In order to-study the effect ,of increasing amounts of arsenic, a series of alloys were made up containing 1 per cent. antimony, and arsenic varying from 0. to 0.10 per cent., the balance Doe Run lead (99.997 per FIG. 1..-CHANGE OF MICRO-BRINELL HARDNESS WITH TIME OF 1 PER CENT. LEAD-ANTIMONY ALLOY. cent. lead). The alloys were cast into bars 1 ½ in. wide by ¾ in. thick and cold-rolled to about 1/8 in. thickness. Three samples of each composition were annealed 1 hr. at 225° C. and quenched in water. One set was aged at room temperature, one at 50° C., and the third at 100° C., the

Jan 1, 1929

By Heather N. Dougherty

In the absence of values for each influencing parameter and a known relationship of input-output space, novel approaches should be implemented as proxy solutions to mathematically complicated problems. Proxy solutions can be in the form of linear or non-linear multiple regression equations. Predicting the performance of gob gas ventholes is one of these mathematically complicated problems as it is difficult to know the exact relationships between various parameters influencing gob gas venthole (GGV) performance from active and sealed (completed) longwall panels. In this paper, a discussion of the NIOSH-developed software suite for methane control and prediction (MCP) based on an artificial neural network (ANN) is presented. The application of the ANN-based software suite to develop algebraic relationships for gob gas venthole performance prediction in sealed and active longwall panels is sought. Output information obtained from the NIOSH-MCP software as a response to various input parameters were used to create an input-output database for total flow and methane percentage from GGVs operating in active mines during completed and sealed panel situations. Due to the multi-variable nature of the software, outputs generated using the software for various inputs were used to develop analytical equations first using linear and then second using non-linear multivariable regression techniques. The advantage of this method is its ability to better understand the significant parameters of the relationships between the inputs and outputs for gob gas venthole production in active and sealed panels and to be able to predict their performances using relatively simple analytical functions.

Jan 1, 2010

By Detnet Solutions

1. “Daisy-Chain” concept The term “daisy-chain” stems from the fact that when the HotShot? detonators are connected there is a chain or electrical path for electrical current to flow from detonator A to detonator B, detonator B to detonator C etc until the path is terminated by an electrical means. The “daisy-chain” concept has long been used in electronic detonator systems, historically used in Expert Explosives’ ExEx 1000 5/6 wire system and currently in use in African Explosives Limited (AEL’s) Electrodet? electronic detonator system and has been adopted as the basis upon which the “auto-programmability” of the HotShot? electronic detonator system functions. HotShot? Detonators are connected to each other in a string, completing a “daisy chain”, and during the auto-detection mode of the control equipment, it is possible for the equipment to determine the order of hookup of the detonators as well as map the entire blast layout. The auxiliary components (Row Controllers & Branch Controllers) assist the control equipment in mapping the entire blast by indicating different points on the blast, i.e. The inflection point of a row of blast holes on a closed chevron timing pattern, the beginning of row of blast holes on open chevron timing pattern and extra blast holes or extra blast rows.

Jan 1, 2004

By Kenneth Eltschlager

Business says that location is a primary component of being successful. So too is the importance of location in blasting. For blast seismograph data to be useful, the location of the blast and seismograph must be clearly documented. Another location of importance is that of a nearby structure. Establishing the spatial relationships between the blast, seismograph and nearby structures, allows the blaster to correctly interpret the data, evaluate the performance of the blast and gauge the validity of any complaints.

Jan 1, 2004

By Å. Kruukka, H. F. Broicher

The iron ores of the Kiruna mine in Sweden are of exceptional quality except for the phosphorus content in certain zones of the orebody. The prevention of mixing ores high in phosphorus with those low in phosphorus has always been of significant economic importance. The ongoing introduction of tele-mining and automatic haulage by LHDs requires new means in the field of quality control underground, as the experienced miner as well as the underground laboratory assistant no longer are involved in the process. As of 1998, LKAB has been testing prototypes of LIF (laser-induced fluorescence) analyzers for non-contact and real-time measurement of the phosphorus content of ore being transported by LHDs from the stopes to the respective ore pass assigned to a certain ore quality. The principles of the analysis of laser-induced fluorescence, the different test phases and results are described and conclusions made. With bulk sorting of ore underground, the mining engineer supports the efforts of the metallurgist in the processing plant.

Jan 1, 2002