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By Clara María Lamus Molina

The following minerals found in the residual black sands from gold mining in El Bagre Antioquia (Colombia) were identified as having major economic interest: Ilmenite (FeTiO3), with an average of 49% of TiO2, frequently altered presenting crowns; lamellaes of rutile and alteration textures; titanomagnetite with up to 25% of TiO2; magnetite (Fe3O4) in individual grains or associated with others minerals as hematite and ferromagnesian silicates rutile (TiO2) with considerable quantities of Nb2O5(0.1-3.7%Wt); zircon (ZrSiO4) with 66%Wt of ZrO2 and monazite with an average of 63.43%Wt of REE, this frequently associated to xenotime and thorite forming textures as little drops. Analysis in EPMA and SEM/EDS showed percentages of minor elements and traces, thereby clearly establishing the applications of these minerals in diverse industries. Furthermore, a detailed granumetric study of the different minerals and textural relationships among them also allowed for establishing the basis for possible processing and exploitation.

Jan 1, 2006

By Kathleen M. Kowalski

In emergency management, the effects of stress on the performance of emergency personnel, typically have been ignored or regarded as too enigmatic to quantify. This paper discusses the concept of Critical Incident Stress in responders to emergencies. It presents the rationale for considering stress as a significant factor in the management of emergencies. It is proposed that Critical Incident Stress Debriefing in a disaster can improve the effectiveness of response teams on site, their turnaround time on site, and post-disaster time off the job. Critical Incident Stress intervention also can mitigate potential deleterious emotional effects associated with emergency work. This paper, prepared by a U.S. Bureau of Mines researcher, offers some ideas to the mining industry in general, to mine rescue team trainers, and to developers of program simulations on the specific issue of how people, time, materials and space may be factored into a plan for emergency management. The impact of stress on emergency workers is, presented as a missing component in present emergency management models.

THE following short paper on the Blair Athol coal-field will no doubt have a twofold interest to members from the fact that its main seam, known as the "Big Seam" of a maximum thickness of 91 ft without a band, is unique, being probably the thickestseam of high-grade clean coal yet known, and also because of the interesting problem it presents the colliery engineer-viz., which system of mining is the best to secure the highest economical extraction.Location - Blair Athol is a mining township in Central Queensland, situated at an altitude of about 1100 ft. above sea-level at the end of a branch railway line 74, miles from Emerald, on the Main Central Western line, and 240 miles by rail from Rockhampton.Geology - The coal-measures appear to lie in a shallow basin of about four or five square miles in area, surrounded on all sides by slates and schists, which are overlaid oh three sides by alluvial deposits of up to 150 ft. in thickness, and on the fourth by a thick basalt bed, as yet unproved, some miles beyond which the auriferous slates outcrop. These alluvial deposits have been largely worked in years past and gave high gold returns, the chief diggings being Clermont and Macdonald's Flats in the south, the Springs and Black Ridge in the north-east, and Yankee Creek and others on the west. The surface of the coal-fields may be described as unbroken, but undulating, with gentle southerly dip, the watercourses opening out into wide flats. The absence of creeks or deep gullies accounts for no outcrops being visible on the surface, and the coal-measures...

Jan 1, 1918

By James J. Anthony

High-angle in-pit conveying is an idea that is being seriously studied by a number of important mining companies in North America. Its application in coal, iron ore, and copper mining is expected to reduce mine operating costs considerably compared with the conventional discontinuous methods, such as truck haulage, which are fuel, labor, and maintenance intensive. Therefore, a mine introducing high-angle in-pit conveyors will gain a competitive advantage over mines which continue to use conventional haulage. While the capital outlay for in-pit conveyor systems obviously varies depending on pit depth, the angle of incline, and the capacity required, it generally will not exceed that of truck haulage when all Factors are taken into consideration. These factors include the cost of excavation, as measured in relation to the volume of minerals mined, the cost of building truck ramps and roads, and the capital outlay for the trucks and maintenance facilities. In many cases, in Fact, the capital outlay will be less than for truck haulage. This cost advantage will best be realized by new mines, whereas in existing producing mines the switch from truck haulage may involve the abandonment of a substantial capital asset.

Jan 1, 1983

By Qingwei Wang

Heavy metal-containing wastewater from hydrometallurgical processes of lead-zinc was treated by biologics in a 200 m3/h industrial scale experiment. The result shows that Zn concentration declined from 50.28 mg/L~240.81 mg/L to 0.21 mg/L~1.98 mg/L, Pb from 1.00 mg/L~13.47 mg/L to 0.083 mg/L~0.71 mg/L, Cu from 0.24 mg/L~2.38 mg/L to 0.059 mg/L~0.40 mg/L, Cd from 2.12 mg/L~23.47 mg/L to 0.011 mg/L~0.071 mg/L and As from 0.50 mg/L~6.00 mg/L to 0.005 mg/L~0.10 mg/L. The concentrations of the above heavy metals in the treated water were lower than that in Integrated Wastewater Discharge Standard (GB8978~1996) in China. Furthermore, the treated wastewater was recycled and reused in smelter plant. Zinc content in hydrolytic sludge reached up to 34.04%, which indicates that this sludge can be used to recover valuable metals.

Jan 1, 2010

By Francisco Alberto Marreiros da Rocha Filho

A corrosão é um fenômeno que está intimamente ligado à integridade dos metais e de suas ligas. Esta ocorre de diversas formas, uma das principais é a corrosão localizada na forma de pites, objeto de análise desse estudo, que visa estabelecer um comparativo entre as curvas de polarização cíclica de algumas ligas ferrosas e não ferrosas, ensaiadas em solução de NaCl 0,6 M, mostrando a agressividade que a solução exerce sob cada uma das ligas. Os materiais analisados nesse estudo foram os aços inoxidáveis AISI 304, AISI 444, super duplex ASTM A890/A890 M Grau 6A, o aço carbono AISI 1030, o alumínio comercialmente puro, o cobre eletrolítico e a liga zircaloy- 4. Inicialmente foram medidos os potenciais de corrosão (Ec) de cada liga através do monitoramento do potencial de circuito aberto. Foram realizados os ensaios de polarização potenciodinâmica cíclica em cada liga, comparando o aspecto superficial antes e depois do ensaio através de micrografias óticas, possibilitando que fossem observadas as diferenças entre cada material quanto à resistência à corrosão por pites. Observou-se que algumas ligas não apresentam passivação como o caso do alumínio comercialmente puro, e outras apresentaram regiões passivas e histereses bem definidas, ficando evidente que, dentre as ligas analisadas, o aço inoxidável super duplex ASTM A890/A890 M Grau 6A apresentou os melhores resultados frente aos efeitos agressivos dos íons Cl- presentes na solução, sendo o menos suscetível à corrosão por pites.

Aug 17, 2017

By Arunsiva R., Sivaranan S., Venugopal B., Kumaran M.

Being a rapidly developing country, India is undergoing a massive infrastructure phase change remarkably. The construction industry is already set to boom, but the time and space constraints necessitate the employment of heavy plants and machinery to take the foundations deeper than ever. Operating such machinery on soft or poor ground conditions without a good working platform leads to uncertainties with massive loss of men and machinery. Plenty of such cases can be observed on construction sites across the globe. Unfortunately, forming a temporary working platform is given least to no importance in the construction industry, particularly ground engineering. This glitch can only be addressed through standard guidelines or codal recommendations on designing and implementing temporary working platforms issued by regulatory bodies. The present paper highlights the importance of providing the working platform, existing design method for working platforms such as TWf 2019:02 of Temporary Works forum, Building Research Establishment BR470 and a brief discussion on the design and construction of the geosynthetic reinforced working platform with a case study is also included. A pitch has been made on the importance of Indian codes/guidelines for the design and construction of temporary working platforms. These guidelines will ensure the safety of the men and heavy machinery and, in addition, increase the productivity of foundation construction irrespective of weather conditions and also become part of the regular construction scope.

Sep 1, 2022

By Brian Y. Lattimer, Kray D. Luxbacher, Jonathan L. Hodges, Manuel J. Barros-Daza

The abstract discusses the importance of predicting fire response time (the time before conditions become untenable for firefighters) in underground coal mines. It introduces a data-driven approach using artificial neural networks (ANNs) to predict response time and fire size based on measurable parameters like CO concentration, mine geometry, air velocity, and time since fire detection. The approach was tested using simulations from fire models (FDS and FSSIM), showing promising results for real-time predictions during mine fires.

Mar 6, 2022

By Ihsan Berk Tulu

In the Analysis of Retreat Mining Pillar Stability (ARMPS) program, the magnitude of the abutment loading adjacent to a gob area is calculated using an ?abutment angle? concept. The extent of the abutment loading is determined solely as a function of depth from an empirically derived equation. In the recommended calibration method for LaModel, it was believed that the empirical equations for calculating the magnitude and extent of the abutment load, as used in ARMPS, were the best available methods for determining these critical overburden loading values. Therefore, similar calculations were implemented in the LaModel calibration method. However, the latest in situ stress measurements of abutment loading performed in the United States and Australia have shown that there can be significant deviations in the measured abutment magnitude and extent as compared to the predicted values from the empirical formulas used in ARMPS and LaModel. It seems reasonable that the overburden geology, depth, extraction panel width, and mining height should have a significant effect on the extent and magnitude of the abutment load. However, the current empirical formulas do not incorporate many of these significant parameters into determining the abutment load on the pillars. In this paper, stress measurements from US and Australian mines were back-analyzed by using analytical and numerical methods to investigate the measured abutment extent and loading. Ultimately, it was determined that the original empirical abutment extent formula in conjunction with the original ALPS square-decay stress distribution function was supported by the case histories in this paper. Also, for depths less than 900 ft, the average 21° abutment angle was supported by the case histories; however, at depths greater than 900 ft, the abutment angle was found to be significantly less than 21° and should be calculated with a new proposed equation.

Jan 1, 2012

By A. Kazemi, M. A. Ahmadi

Pressure tunnels are constructed nurously in related with powerhouse. In some cases, according to high internal water pressure, rock mass around tunnel can seldom suffer this pressure. So installation of concrete lining which interacts with rock mass and suffers parts of this pressure and transfers the rest of the pressure to the rock. In this paper hydromechanical interaction between rock and lining is investigated. With using empirical and numerical methods concrete lining for Symareh waterway is designed. Initial support of 10 cm reinforced shotcret with wire mesh and rock bolts pattern of 2.5*2.5 m with length of 4 m is suggested. By using FLAC package final lining with paying attention to axial force and momentum in reinforced concrete was designed. Reinforced concrete with 60 cm thickness and two rows of bars, 18 mm diameter and 20 cm spacing are designed. Also for preventing cracks in concrete which caused by the change of temperature and shrinkage, bars with 10 mm diameter and 25 cm spacing, and also bars with 8 mm diameter and 10 cm as minimum shear bars are suggested. Plusieurs galeries en pression se construisent en liaison avec les centrales électriques. Dans certaines galeries, suite à une haute pression interne de l'eau, le massif rocheux autour de la galerie ne peut pas supporter cette pression. L'installation d'une couche de béton a l'intérieur de la galerie donc réagit avec les roches et support d'une partie de cette pression et transfère le reste de la pression aux roches. Dans ce papier, l'interaction hydromécanique entre la roche et la couche en béton a été étudiée. En se basant sur les méthodes empiriques et numériques le système de support de galerie de passage d'eau de Saymareh a été conçu. Un soutènement initial d'une épaisseur de 10 cm de béton étant renforcé par un grill métallique et une maille de boulon (2.5 * 2.5 m) d'une longueur de 4 m a été proposé. En utilisant le logiciel de FlAC, la couche finale en béton selon les forces dans le béton a été conçue. Le béton renforcé d'une épaisseur de 60 cm et deux ranges d'armateurs (18 mm de diamètre) avec un intervalle de 20 cm a été conçu. De plus; pour éviter des fissures dans le béton suite au changement de la température et de l'extraction, des armateurs de 10 mm de diamètre et de 25 cm d'intervalle pour augmenter la résistance au sciesiement du béton ont été proposes Unter Druck stehende Tunnels werden hauptsaechlich im Zusammenhang mit Kraftwerken gebaut. In einigen Faellen, wo der Wasserdruck zu hoch ist, Kann selten die Felsenmasse diesen hoehen Druck allein aufnehwen. Deshalb werden sie mit Betonauskleidung versehen, die wegen guter Wechelwirkung mit der Felsenmasse einen Hauptanteil des Druckes aufnehmen Kann, wobei der Rest an die Felsenmesse weitergeleitet wird. In dieser Arbeit wird die hydromechanische Wechelwirkung zwischen der Gesteinmasse und der Auskleidung untersucht. Mit Hilfe empirischen und numerischen Verfahren sowie Kombination der beiden wurde eine Betonauskleidung fuer die Symareh Wasser Kannal koustruiert. Als erstes wurde ein 10Cm dicker armierter Beton mit einem Mashengitter von 2.5*2.5 sowie den gleichen Felsbolzenabstaenden und einer Laenge von 4 m vorgeschlagen. Mit Hilfe des FLAC Programms wurde die Hauptauskleidung unter Beruecksichtigung von Axialkraeften und Momenten im Stahlbeton koustruiert. Der 60 Cm dicke Stahlbeton wurde mit zwei Reihen von Stangen, 8 mm im Durchmesser und in Abstaenden von 20 Cm koustruiert. Ferner im Sinne der Vorbeugung gegen Rissen im Beton, die durch Temperatur aendeungen und Schrumpfungen bedingt sind, wurden Stangen mit 10 mm Durchmesser und 2.5 Cm Abstaenden zur Erhoehung vor Scherfestigkeit des Betons vorgeschlagen.

Jan 1, 2003

By Leo Panian, Ryan Nagle, Priyanshu Singh, Gina Carlson, Wayne Magnusen

"This case study presents the design and construction of an integrated foundation and ground improvement solution utilizing deep soil mixing (DSM) and micropiles. 270 Brannan is a midrise office building in San Francisco that straddles the historic shoreline that was reclaimed in the 19th century. Subsurface conditions include shallow bedrock inland of the historic shoreline, and steeply dipping bedrock overlain by 60 feet of compressible deposits and liquefiable fill on the bay side. Project challenges included mitigating the liquefaction and lateral spreading hazards, addressing settlement concerns in the fill and the bay deposits, developing a cost-effective foundation support solution, assuring satisfactory seismic performance, and addressing construction restrictions with existing adjacent structures.DSM combined with micropiles was identified as the most cost-effective solution for the ground conditions. The DSM panels act both as a liquefaction mitigation mechanism and a foundation support system. Resistance to seismic overturning is provided by uplift-resisting micropiles. The DSM-micropile solution allows the use of efficient conventional spread footing foundations, integrating isolated micropile groups to anchor the shear walls. Successful installation of the system relied on a program of field testing to validate the design and conformance with the design criteria.INTRODUCTIONThe regular grid of surface streets within San Francisco’s South of Market (SOMA) district provides little evidence of the geotechnical complexities that lie below. In the late 1800s, sand dunes, bedrock hills, cliffs, marshes, and mud flats were flattened and filled, concealing their locations and characteristics. The 1906 San Francisco earthquake and fire leveled many buildings in SOMA; new buildings were built after 1906 – often on top of rubble and debris from the structures that came before. Locally, the combination of natural geology and historical interventions can produce complex subsurface conditions that vary dramatically over short distances. This is particularly true at locations where tidal mudflats once met bedrock hills at the shore of San Francisco Bay.This case study describes an integrated foundation and ground improvement system implemented for a multistory “Class A” office building at a complex SOMA urban infill site. The system utilizes cement deep soil mixing (DSM) in combination with spread footings and micropiles to address a range of design and construction issues, including liquefaction and lateral spreading mitigation; consistency of earthquake ground motions; shallow foundation support; seismic uplift resistance; and avoidance of loading adjacent basement walls. The system was implemented by a technically-sophisticated owner through a process that included constructive collaborations between the project geotechnical engineer, structural engineer, general contractor, and specialty foundation and ground improvement contractor(s). The system is designed to cost-effectively provide a high level of seismic performance."

Jan 1, 2017

By A D. Campbell

Sublevel caving (SLC) is a mining method adopted in a wide range of mining depths and ground conditions with various layouts adopted to suit orebody geometry. Sublevel caving offers more flexibility and versatility compared to other cave mining methods and is a low cost alternative to open stoping. SLC also has the advantage that stopes are not required to remain stable during production, and no backfill is required. This flexibility combined with increasing pressure on mines to target deeper and lower grade mineralisation has led to increased uptake of the method. The implementation of SLC mining methods across a wide range of mining depths and rock mass conditions has led to ground control practices which vary globally from mine to mine. To date, there has been limited documentation of ground control practices in SLC mining and few benchmarks available in the literature. This paper describes the main findings from a global benchmark of sublevel cave mines conducted over three years as part of the Caving 2040 research consortium. The purpose of the project was to document and compare operational practices, technical aspects and hazard management techniques across SLC mines around the world. The review included 21 mines spread over four continents and 17 different mining companies. This paper provides an overview of geotechnical conditions, challenges and ground control practices at each of the benchmarked SLC mines. Mine design and sequencing practices adopted for ground control purposes and hazard mitigation are provided with case studies. The impact of depth and rock mass conditions on mining productivity and development rates is also described.

Nov 29, 2022

By Farzad Moradpouri, Kianoush Barani, M. R. Azadi

The aim of this paper is to assess the effect of microwave treatment on copper sulfide ore for ball milling and bed breakage. Liberation analysis of ground products in eight size fractions showed that microwave pretreatment liberated more chalcopyrite particles from the bed breakage product than the ball mill product. In bed breakage, microwave pretreatment caused a 2% increase in chalcopyrite liberation on average. Microwave pretreatment produces more elongated particles in ball milling and more rounded particles in bed breakage, respectively. Microwave pretreatment produces coarser chalcopyrite particles with a wide range of sizes. This effect is more significant in bed breakage compared with ball milling. Micro-flotation test results showed that in ball milling, treated and untreated materials have similar metallurgical performance and there is a little difference (1%) between the average Cu recovery values. However, in bed breakage, the average recovery for the treated materials is about 5% higher than the untreated materials.

Jul 8, 2021

By Xinhua Wang, Qiangqiang Wang, Yubin Li, Shusen Li, Lifeng Zhang

"Numerical simulation on the fluid flow in a Flow-Control Mold (FC-Mold) were performed. The motion of inclusions were calculated. With FC-Mold, the flow pattern and surface velocity become more symmetrical, and at higher casting speed the velocity of liquid steel in the top region of the mold was largely reduced with the highest velocity of the meniscus reducing from 0.65 mis to 0.4 mis, and the meniscus shape became flatter. With FC-Mold, more inclusions approached to the surface of the slab and the amount of inclusion in the center of mold became fewer. Larger inclusions were easier to remove, however, the EM filed of the FC-Mold could hardly improve the removal of inclusions from the molten steel.IntroductionElectromagnetic brake technology is an effective method to control the flow pattern within continuous casting mold, together with other casting parameters, nozzle design and mold geometry [1-5]. Due to the interaction between the applied magnetic flux and the conductive molten steel inside the mold cavity, a force is generated in the direction opposite to the jet flow, which can decelerate the high speed steel jet from the SEN ports. The potential benefits include fewer surface and internal defects, fewer inclusion especially at higher casting speed. However if used imperfectly, electromagnetic forces can have opposite effect [6]. Numerical models are the best tool to optimize electromagnetic flow control. In the current study, numerical simulation was performed to investigate the flow field in a continuous casting FC-Mold, and the effect of different operation parameters on the flow, surface level and velocity in FC-Mold were discussed."

Jan 1, 2013

CONTENTSThe significance of values givenINTRODUCTIONTHE ORE1. DATA SECURED FROM THE MILLING PLANT AS OPERATING BETWEEN 1938 AND 1942(a) Mill Recoveries(b) Mill Flow Sheet(c) Scheelite-Garnet Association(d) Detailed Examination of Mill Performance during 1942Crushing UnitsCoarse Rolls DischargeFine Rolls DischargeFeed to Huntington MillsFinal Ground ProductProduction of -200-mesh Scheelite SlimeSummary of Information on Crushing and Grinding Circuit(e) Detailed Examination of Mill Performance During 1942Concentrating UnitsLocation and Nature of Scheelite LossesSize Distribution of Scheelite LossesDistributor Spigot ProductsSummary of Information on Concentration Circuit(f) Detailed Examination of Mill Performance During 1942 Gravity Plant Feed2. EXAMINATION OF MINE SAMPLES TAKEN DURING 1942(a) Introduction(b) Nature of the Ore(c) Sampling of Mill Feed(d) Testing Technique(e) Minus 1/8-inch Ores-Naturally Broken Fractions(f) Recoveries from Plus 1/8-inch Fractions-Crushed to Minus 1/8-lnch(g) Probable Recoveries Obtainable from Weathered Ores140 Contour120 Contour90 Contour(h) Examination of an Ore Sample from the 90-foot Adit(i) Run-of-Mine Ore(j) Evidence of Maximum Sizes of Scheelfte Present in Run-of- Mine Ore(k) Summary of Information on Liberation and Recovery from the Ores as Mined in 1942 and from the Mill Samples

Jan 1, 1944

By A Croll

A panel cave using LHDs for ore extraction came into production at Premier in 1990 at a depth of 630 metres below surface on the western side of the mine in the BA5 mining block. A post-undercut mining sequence was used with all development on both the undercut and production levels completed prior to the undercut being advanced over the pre-developed drawbells. Support and rock mass damage on the production level was extensive as the undercut moved overhead. Undercutting and coarse fragmentation created problems. The mining sequence was changed to an advance undercut with the minimum of development and support undertaken on the production level prior to the undercut moving overhead. Only once the abutment stresses had stabilised were drawbells developed and final support installed. The height of the undercut drill design was decreased from 18 to 13 metres. The changes resulted in markedly less rock mass and support damage on the production level. Lessons learned in the BA5 mining block on the 630 level were incorporated into planning and scheduling the BB1E mining block which came into production on the 732 metre level on the eastern side of the mine in 1996. An advance undercut mining sequence was planned, undercut height was minimised and undercutting parameters were optimised in terms of the BA5 experience. Numerous problems still occurred. As the undercut area increased in size severe spalling from the cave back resulted in vertical propagation of the cave to a height of 30 metres instead of the planned 13 metres. The resultant coarse fragmentation created secondary blasting problems and an excess of undercut ore that had to be loaded and trammed, slowed the rate of undercut advance. The planned mining sequence was compromised and considerable support and rock mass damage resulted on the production level below. Once these problems had been overcome the undercut advanced at the planned rate and continuous caving initiated at the predicted hydraulic radius. At a later stage the unexpected ingress of water hampered undercut drilling and slowed the rate of undercut advance in a section of the cave. Leads and lags between adjacent tunnels and the overall face shape could not be developed as planned. The rate of natural horizontal cave propagation exceeded the rate of undercut advance and three undercut drilling tunnels were extensively damaged. More tunnel development on the production level prior to undercutting than was planned resulted. The slow advance of the undercut and high abutment stresses caused extensive damage to installed support and the rock mass on the production level, 15 metres below. Experience in the BB1E mining block on the 732 metre level has taught that an advance undercut mining sequence reduces damage on the production level markedly. Extremely tight control on the rate of undercut advance, leads and lags between adjacent tunnels and overall undercut face shape as well as extraction ratio, tunnel development and support sequence on the production level below is required. Premier Mine plans to implement a block cave at a depth in excess of 1000 metres within the next decade. All the experience gained on current mining levels together with data collection and numerical modeling is being used to plan the proposed mining operation. The geotechnical challenge of mining at this depth in weak rock has been identified as the greatest risk to the project. Challenges centre around adopting the correct mining sequence, limiting the extent of rock mass damage associated with undercutting and effective support. The hydraulic radius needed to initiate caving, fragmentation, drawpoint spacing, secondary blasting and the possibility of seismicity are geotechnical concerns that are being addressed. Results to-date suggest that a pre-undercut mining sequence with all development and support on the production level carried out only after the undercut abutment stresses have passed overhead will have to be implemented.

Jan 1, 2000

By K. E. Robinson

Appendix A is an abridged extract of the report prepared by the Geotechnical and Structural Engineering Society of Idaho, and presents the results of their one-year study to evaluate the feasibility of disposing mill tailings by landfill construction. Appendix B describes the field and laboratory testing program completed by RDM to assess the effectiveness of a soil (slimes) liner as a means of seepage control to reduce the introduction of contaminants into the local ground water regime. Appendix C presents a summary of a thesis by Lawrence Martin on the analysis of the acid production potential of mill tailings, and the results of geotechnical testing of mill tailings completed by ROM. Appendix D describes potential landfill sites identified within the study area, the development of these sites to meet the present needs of the mining industry and the future requirements of the community is described. Appendix E summarizes the main legislation impacting on tailings disposal. Appendix F discusses the environmental and socio-economic factors that should be considered.

Jan 1, 1981

By B. A. Slaker

The ability to detect and quantify ground movements in underground mine workings is of the utmost importance to the safety of miners and continuity of operations. Rib sloughage is one of the most common forms of underground deformation. Remote sensing techniques, such as laser scanning, can be used to quantify this rib sloughage, by recording precise, timelapse point clouds of mine workings. In order to determine sloughage volumes and locations, two sets of laser scans were performed 42 days apart at a working section of an underground limestone mine. During this period, significant sloughing and scaling occurred, allowing for differentiation between the initial and final point clouds. Volumetric changes of 2.3-2.6 m3 were detected on rib faces during the time-lapse study. In addition, displacement in the mine roof was, as expected, not detected, suggesting well surveyed scans and an appropriate scan resolution.

Nov 1, 2013

By John B. Knaebel

This paper is one of a series being prepared by the Bureau of Mines on mining methods and costs at various mines in the United States, Canada, and Mexico, and is a description of practice at the Edwards mine of the St. Joseph Lead Co. ACKNOWLEDGMENTS The cooperation and assistance of the officials of the St. Joseph Lead Co. in permitting publication of this paper and providing every facility for its preparation are gratefully acknowledged. Especial thanks are extended R. J. Mechin, manager, R. F. Mitchell, mine captain, and J. S. Brown, geologist, for their generous aid, and the assistance of W. H, Weijola, mine engineer in assembling some of the illustrations is deeply appreciated, The helpful suggestions of C. F. Jackson, principal mining engineer, U. S. Bureau of Mines, are gratefully acknowledged.

Jan 1, 1932

By Jerry B. F. Champlin

NIOSHAn accelerated testing procedure developed by the Bureau of Mines for evaluating commercially available corrosion inhibitors is described. Ultra-sonic agitation of the corrodent solutions and the hot-finished mild steel test coupons was used to evaluate the effects of several variables on the effectiveness of two corrosion inhibitors. Small changes in the weight of the test coupons in both controlled and inhibited corrodents, before and after exposure, affected the precision and accuracy of the results. Minute amounts of oxygen in the systems were found to be causing the relatively large deviations in the corrosion developed in the controlled tests. Microscopic examination of the test coupons revealed that both surface preparation and internal strains resulting from fabrication methods materially affect corrosion behavior.

Jan 1, 1965