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By P. Cienfuegos, J. Loredo, J. J. Fernández, F. Pendás

This coal basin is a fore-deep basin with a lot of similarities with the Appalachian basin in the U.S.A., where throughout the 1990s, the research in coalbed methane grew rapidly due to a combination of factors, including the high prices for gas and electricity. In the Asturian Central Coal Basin 129 coal beds with thickness ranging from 0.8 to 1.5 m have been recognised in the productive carboniferous in an area bigger than 1500 km2. The maturation grade of these coals varies from the external zones of the basin where the volatile content ranges from 35%-40% to 20%-30%, to the internal zones of the basin where the volatile content ranges from 20% to 10%. In this context a sustainable exploration for fossil fuel is currently being undertaken in the most favourable areas of the basin in order to evaluate the real possibilities for coalbed methane (CBM) resources.

Jan 1, 2005

By M. W. Grabinsky

Better in situ performance data is required in order to advance the rational geomechanical design of cemented paste backfill systems. A few in situ test programs have been conducted, but these have suffered from too few measurement locations within the stope and have not used enough different types of transducers to fully capture the information of significance. In this paper the important geomechanical design aspects are listed, the underlying physical phenomena are described, and some previous in situ measurement efforts are reviewed. A new approach to in situ measurement campaigns is then described including measurement techniques, locations, and the logistical aspects of mobilizing transducers in an active mining environment. A work-in-progress is used to illustrate the principles and concepts involved.

May 1, 2007

By Arun Kumar Singh

Wide variation in the nature of the coal seams and the surrounding rock mass of the Indian coalfields and very little information about the associated stress fields were observed to be the major hurdles in the straight forward application of a continuous miner (CM) based mechanised depillaring approach. Due to various techno-economic reasons, a considerably large number of coal seams have been developed and are standing on pillars in India. The development of pillars is done as per Indian coal mines regulation, which results in pillars of relatively large size. In fact, the large size of the pillars provides stiff natural support to control caving of the massive overlying strata. However, the size of these pillars is not conducive for the single pass pillar stripping technique and, therefore, there is a need for pillar splitting before pillar extraction/retreating. Splitting of the pillar may reduce the competency/stiffness of the pillar, which creates a chance of overriding during final extraction below a massive roof stratum. This paper first discusses the existing coal mining scenario in India followed by a brief presentation of geo-technical details of pillar extraction at the three sites where a CM has been introduced for depillaring/pillar retreating in the country to date. Based on past rock mechanics experiences with conventional depillaring faces, stability issues of the pillars, fenders, and stumps in and around the depillaring face are discussed. This may prove to be an important factor in the success of future CM faces. It is recognized that the application of the modern strata movement monitoring techniques may improve operation safety by providing valuable qualitative and quantitative information that can be used to improve the design of modern concepts like roof bolt based breaker line support during pillaring.

Jan 1, 2009

By D. C. Fleck

Electrorefining yttrium from selected low-melting yttrium--base alloys is investigated, and various halide systems are studied as potential electrolytes for use in preparing low-oxygen yttrium by electrorefining unalloyed yttrium. Yttrium cathode products having significantly less metallic impurities than the anode materials were prepared from alloys containing nickel, iron, and manganese by electrorefining in LiCl-YC13 electrolytes at 900° to 1,000° C. Yttrium-copper and yttrium-magnesium alloys are not suitable as anode feed materials, An evaluation of chloride, fluoride, bromide, and mixed chloride-fluoride electrolytes showed that cathode products containing much less oxygen than the anode material can be obtained in the fluoride and mixed chloride-fluoride systems. Initial cathode current density has no apparent effect on the purity of the products obtained in both phases of the investigation.

Jan 1, 1973

By Gustavo E. Armijo

This job was done in Morristown, NJ, with mono fluid system jet grouting for the construction of a new bank building. After the demolition of the existing two story structures, an excavation in loose sandy fill materials was necessary in order to reach the new structure basement level. Due to this jet grouting was selected as a medium to provide both excavation support and permanent underpinning, minimizing the adjacent building settlements. These two adjacent buildings were partially underpinned with a "gravity wall" made with 2 and 3 rows of secant vertical and inclined jet grout columns. Besides the classical jet grouting control methods, during the jet grouting execution, all the drilling and grouting parameters were recorded by a proprietary system called "Slogger". Additionally, after the jet grouting execution, an innovative result control technique was used by means of the application of the same parameter recording system. Some of the production columns were re-drilled and a comparison was made between the obtained drilling parameters and those obtained for the same age test columns. Under the referred existing conditions and in comparison with the conventional underpinning techniques, this project demonstrated that jet grouting, with proper execution and result control, can be faster than them and can maintain the building structural stability and act, at the same time, as a retention system minimizing the existing building settlements.

Jan 1, 2002

By P S. Datta, V N. Misra

Higher bed height up to 680 mm, including 30 mm hearth layer of sized return sinter and high suction below the grate bars up to 1400 mm WG have resulted in increasing the productivity to a level of 33 t/m2/day and reduced coke rate to a level of 46 kg/tonne sinter. The ferro-wastes like blue dust, flue dust, mill scale, collection from dust catcher and gas cleaning plant, etc have been successfully added in charge mix to produce quality sinters. In this paper, brief description of the work done at Regional Research Laboratory (CSIR) in last few years and two case studies are discussed including the successful development of pan sintering units.

Jan 1, 2002

By Christoph Miller

About 80 years ago the mining industry saw an advertisement of a machine manufacturer: ?One man ? one machine?, meaning the productivity gain by using a pneumatic rock drill instead of manual tools. Mechanization in mining had started. In the 1950's and 1960's when mechanization progressed the word could be transformed into the meaning of ?one man ? one drill rig?. During the 80's automatic functions were added to the machines. Automation started. In the 90's, the first autonomous machines were seen, transforming the advertisement from the 1920's into ?one man ? multiple machines? operated from a remote control room. Soon, the productivity gain achieved by pure automation will also be flating out meaning that the margin cost of further productivity gain will be inefficiently high. What next? In mining operations there is still a high potential of unused productivity lost by ?trivial? things like organization, logistics and operational management. Changing the focus from mechanization and automation towards optimizing the overall mining process will unleash another big potential for cost cuttings and for enhancing efficiency of production. Optimizing an overall process is a task of much higher total complexity compared to an isolated machine automation focus. And a successful process integration requires the collaboration of machine vendors, infrastructure suppliers, IT services and the mine itself. It requires a number of of important preconditions to be fulfilled: ? Integrated IT systems with seamless interfaces between all components and peripherals involved ? Real time information access in all locations ? Real time overview of all operational aspects A crucial aspect for all of these issues is a seamless communication both above and also under ground and IT interfaces which are easy and price efficient to implement. This paper highlights ways to achieve productivity gains by process optimization. It also discusses needs for industry wide activities in order to enable cost efficient performance of mine process optimization projects.

Oct 1, 2009

By Deane Tunaley, Clint Brearley, Steven Kotsonis, Richard Goodridge, Tom Smylie

Explosives are widely used in the Oil & Gas Industry for subsurface mapping via measurement of reflected sound waves as each charge is detonated. To complete a seismic survey, several thousand explosive charges may be deployed into narrow boreholes, often in areas difficult to access or where socio-political factors may increase the risk of unlawful recovery or sabotage of the explosives. Therefore, when misfires occur, the explosives left in the ground often cannot be retrieved or sympathetically detonated safely, in which case they are “abandoned” (in-line with local regulations) potentially posing a safety and security risk.

Jan 1, 2014

By Hong Yong Sohn

Keywords: Barium sulfate, Barium sulfide, Environment, Kinetics, Pollutants, Sulfur dioxide conversion, Thermodynamics Nonferrous smelters and coal gasification processes generate sulfur dioxide streams, most of which are treated to produce sulfuric acid with the accompanying problems of market shortage and transportation difficulties. While the conversion of sulfur dioxide to elemental sulfur has many environmental advantages, no processes exist that are environmentally acceptable and economically viable. A method for converting sulfur dioxide to elemental sulfur by a cyclic process involving calcium or barium sulfide and calcium or barium sulfate without generating solid wastes has been developed. In this process, the sulfate, as the starting raw material, is reduced by a suitable reducing agent such as hydrogen to produce the sulfide, which is used to reduce sulfur dioxide producing elemental sulfur vapor and regenerating the sulfate. The latter is then reduced to reproduce the sulfide. This paper describes work on the BaS/BaSO4 system. Thermodynamic analysis and experimental results indicated that the BaS-SO2 reaction produces mainly sulfur vapor and solid barium sulfate and that the gaseous product from the BaSO4-H2 reaction is mainly water vapor. The rates of the two reactions are reasonably rapid in the temperature range 700-1050°C.

Jan 1, 2005

By Chelsea Woodward

The Spokane Research Laboratory of the National Institute for Occupational Safety and Health has demonstrated a prototype hydrogen-fueled mining vehicle as an alternative to diesel equipment in underground mines. Safety and control systems were added to allow a 70-kW rubber-tired hydrogen vehicle, originally developed by the U. S. Bureau of Mines and Hydrogen Consultants, Inc. (now Hydrogen Components, Inc., of Littleton, CO), to be tested. This work began in late 2000 and culminated with a Mine Safety and Health Administration fire safety review and field tests at the Stillwater Mine in Nye, MT, in 2004.

Jan 1, 2006

By Frederick Laist

AFTER a series of experiments covering a period of about three years, ending from the spring of 19iJ.2 to the spring of 1915, a 2,000-ton leaching plant for the treatment of the accumulated copper concentrator tailing was built and put into operation. During the experimental period, the first step was that of laboratory experiments or beaker leaches. The results on this small scale were so satisfactory that a small operating plant, capable of handling 5 tons of roasted tailing per day, was installed. Again, the results proved satisfactory and an 80­ton plant was built and operated continuously from August until February, 1913. In this plant, full-sized roasting and leaching units were

Jan 8, 1916

By Rudolph P. Frizzi

"Abstract Pile design for building structures in the United States is typically performed by: 1) investigating and assigning engineering parameters to the respective ground bearing materials, 2) calculating ultimate pile to ground (geotechnical) capacity which is then reduced by a Safety Factor deemed appropriate by a registered Design Professional thereby arriving at an allowable pile geotechnical pile capacity, and 3) determining the required pile structural section using allowable pile section material properties. It is advantageous to use a Working Stress Design Method (WSDM) approach as one system of loads (service loads) are used in both the geotechnical and structural evaluation. There are a variety of methods used to determine the ultimate and allowable geotechnical capacity, and Building Codes often require a registered Design Professional to determine the appropriate method(s) and capacities. The International Building Code is the Code typically referenced in building design and construction in the United States. Structural design usually follows Building Code requirements and Allowable Stress Design (ASD) procedures. As design of the overlying structure typically follows a Strength Design Method (SDM) approach using factored loads, in some cases piling is first designed for pile-to-soil interaction using service loads, followed by evaluating the pile geometry for factored loads. Construction is the finalization and implementation of the designed piling. As such, project-specific technical specifications are typically developed by a registered Design Professional such that a project Owner can bid, buy, and instruct a Contractor as to the desired piling work and acceptance criteria. There are several Industry groups, including DFI, PDCA, ADSC, and ACI that provide guidance documents which the registered Design Professional can refer to in developing the piling technical specifications. It is the author’s opinion that the registered Design Professional is best suited to observe and verify the piling installation; many Building Departments require verification and documentation by a registered Professional as a condition of final acceptance.INTRODUCTIONPile design for building structures consists of: investigation, design, specification, and verification. In major metropolitan areas within the United States, Building Codes typically identify minimum requirements for each of the above steps. The International Building Code (ICC, 2012) is the Code typically referenced in building design and construction in the United States. Recognizing the ground conditions as well as piling construction means and methods can vary on a site-by-site basis, latitude is given to the registered Design Professional and Contractor to optimize the piling system for the respective project conditions. Field testing and quality control / assurance measures are typically implemented to verify the design intent is attained for the production pile elements."

Jan 1, 2014

By Steven Townend

Mining-related activities have been known to create a challenging operating environment for mining companies located in close proximity to communities. Issues such as noise, vibrations from mining operations, land use and emissions are often a concern for community residents. In order to develop good community relationships it is necessary to take a proactive approach. This paper documents this approach and also deals with the social implications for Vale associated with mining activities in the heart of the community of Copper Cliff, Ontario, Canada.

May 1, 2011

By Tony Moore, Peter Riccio

"MMG (Minerals and Metals Group) operates the LXML Sepon’s mineral processing facility located 40 kilometers north of the town of Sepon, in the Savannakhet Province, Lao PDR. The Sepon copper plant produces 70,000 tons/year of LME grade A copper cathode using leachautoclave- SX/EW-flotation technology (Baxter et al., 2003). Pyrite recovery in the flotation circuit is critical to the operation, as it is used to generate acid and soluble ferric ion for the leach circuit. Low pyrite recovery has been an on-going challenge in the flotation circuit. Final tailings characterization work done by Ian Wark Research Institute (Bassell et al., 2006) showed that the pyrite losses to the tailings are made up of a combination of coarse liberated particles and finer particles that have been coated by clay fines.In December of 2005, a joint Cytec-MMG technical program was initiated to address the pyrite recovery issue. A series of diagnostic tests were performed in the Cytec Stamford Research Facility using synthetic plant water showing that the collector was precipitating as a metal salt and was unavailable for mineral attachment. The tests also identified several collector chemistries that would likely be robust in the low pH (< 1), high dissolved metal ion environment and will not complex with metal ions in solution. With the support of the Sepon on-site engineers, an extensive, successful laboratory program was completed, which was subsequently followed by on-plant testing that showed a step wise improvement in pyrite recovery.INTRODUCTIONLow pyrite recovery has been an ongoing problem in the flotation circuit at Sepon. Sulfur recovery (indirect measure of pyrite) was improved from 40% to 65%-75% in mid-2005 when on site laboratory work confirmed that AERO® 8045 Promoter was a more effective collector then AERO® 407 Promoter. However, sulfur recoveries above 65% could never be achieved. Sepon requested the Ian Wark Research Institute to complete a surface analysis study using Scanning Electron Microscopy, X-ray Photoelectron Spectroscopy, and Time-of-Flight Secondary Ion Mass Spectroscopy to determine if clay coated pyrite played a role. It was concluded that the pyrite losses to the tailings are made up of a combination of coarse (+ 100µm) liberated particles and finer (-74µm) particles that have been coated by clay fines. The majority of the losses appear to be due to the former. In December of 2005, a series of diagnostic tests were performed in Stamford using synthetic plant water in order to identify what chemistries would likely be robust in the slimy low pH and high dissolved metal ion solution environment. Results showed that several chemistries would not complex with ferric, ferrous or copper in solution and therefore should perform well in the Sepon flotation. The incumbent collector, AERO® 8045 Promoter was complexing with metal ions in solution. This resulted in the collector not being available for adsorption onto pyrite."

Jan 1, 2011

By Elsa Olivetti

Life cycle assessment (LCA) is used increasingly as a tool to provide quantitative metrics of environmental impact and inform early stage materials selection decisions. One common challenge in LCA stems from allocation of burden when multiple adjacent products share some of the same processes. A critical example of this is the partitioning of benefit or burden at product disposition in open-loop recycling scenarios. This work reviews the challenge of allocation and investigates the various methods proposed for allocating end-of-life (EOL) burden. Specifically this work examines whether these methods lead to different results and explores the trends in allocation method bias for or against particular materials classes.

Jan 1, 2010

By Mingju Liu

China has been suffering from coal and gas outbursts since 1950s. Nowadays, the situation has become worse than ever with the need to mine deeper coal deposits at higher production rates in a more complex underground mining environment. In the year 2006 alone, 37 outbursts occurred in underground coal mines with a death toll of 232. This paper describes a case study of an outburst event, which occurred in July 2006 during the shaft development of the Mengjin Coal Mine, Henan Province, China at a depth of 768m below surface. Detailed analysis of the possible causes that led to the occurrence of the outburst is reported. These include the study of complex geological features, gas storage conditions, possible improper technical management practice as well as incomplete prevention and control measures. Based on the case study and the observation of outburst occurrence in China in the year 2007, suggestions have been put forward to help prevent and control future coal and gas outbursts.

Jan 1, 2007

By Dale Preece, C. Mick Lownds

Detonation delay timing has been an important aspect of quality rock blasting for decades. Detonators that enable delay timing have improved over the years especially with the recent advent of precision electronic detonators. The positive effects of precision delay timing have been observed repeatedly in the field with improved fragmentation, heave and overall blast control.

Jan 1, 2008

By R. F. Nielsen, R. G. Bentsen

Jan 1, 1966

By R E. Myers, G N. Phillips

Many of the worldÆs larger iron ore deposits are hosted by rock sequences of Archaean to early Proterozoic age. Most models for the genesis of these deposits are influenced, either directly or indirectly, by the nature of the atmosphere at the time of their formation, and more specifically by the presence or absence of oxygen in the early atmosphere. Since the early-1950s, the geological literature suggests that the Archaean atmosphere was æreducingÆ, and that it may not have contained significant amounts of free oxygen until ca 2 Ga. There are many different definitions of the term æreducingÆ, but the criterion adopted here is whether crustal iron was limited to Fe2+, or whether Fe3+ was also widespread, ie was there scope for redox changes in the state of iron? Significantly, major Australian banded iron formations span this period of inferred atmosphere transition, eg Mt Goldsworthy, Mt Tom Price, Middleback Ranges. Geological evidence for a reducing Archaean atmosphere is both ambiguous and controversial (see review by Phillips, Law and Myers, 2001). Many earlier ideas (eg no Archaean redbeds; all very large iron ore deposits being post-Archaean) have been disproved by dating, whereas other evidence (eg homogeneous detrital gold grains, inferred palaeosols) has not withstood geological scrutiny. The interpretation of some data sets (eg inferred detrital uraninite and pyrite in some Archaean meta-sedimentary rocks) is still controversial. In fact, some lines of evidence now suggest that oxygen was present in the atmosphere well before 2.5 Ga (eg sulfates in the Pilbara craton, carbon distribution in clastic sedimentary rocks). An oxidising Archaean atmosphere has important implications for the development of iron formations. First, the atmosphere is an obvious potential source of oxygen to stabilise ferric iron minerals. Second, reduced fluids in equilibrium with ferrous iron are commonly inferred to transport iron in solution to the depositional site. The redox state of the atmosphere thus provides critical constraints on the solution chemistry of surface waters, effective transport paths for iron and particularly on viable precipitation mechanisms. Iron formations developed from fluids in equilibrium with the atmosphere also have the potential to provide important constraints on the evolution of EarthÆs early atmosphere. If an oxygenated atmosphere is a necessary condition for the development of iron formations, then the Archaean atmosphere must have been oxidising since at least 3.5 Ga. If the redox state of the atmosphere is not a necessary condition, then the time distribution of iron formations cannot be used to provide constraints on atmospheric evolution. Given these uncertainties, models for the genesis of iron ore deposits of Archaean or early Proterozoic age should not rely on a reducing atmosphere in the absence of independent evidence and the alternative of an oxidising atmosphere should also be considered.

Jan 1, 2002

By H.A. Bedworth

AlloTs of copper and silicon have been known for one hundred years or more but the commercial development of this type of alloy has taken place during the past few years. In 1905, Sperry l proposed the use of copper-silicon alloys for springs and other purposes for which copper-tin bronzes were used. Some attention was given to this proposal at the time but no one succeeded in producing a practical alloy containing more than a fraction of a per cent. of silicon. The equilibrium relations of the copper-silicon system were studied first by Rudolfi2 and later by Sanfourche 3 and Corson. 4 The constitution of the system has also been recently investigated by Matuyama, 5 and in the laboratories of the American Brass Co. by Smith. 6 Some of the physical properties of the copper-silicon alloys have been investigated by Norbury7 and by Geiss and Van Liempt.8 Summarizing the results of various investigators of the constitution of copper-silicon alloys, the solubility reaches its maximium value, 6.7 per cent. silicon, between 721" and &apos;782" C. At 852" (1. the solubility is 5.25 per cent., while at 400" C. it is only 4.1 per cent. silicon. The copper-silicon alloy begins to get so hard at about 3 per cent, silicon that it is difficult to manage. It was found by Jacobs that the addition of manganese to this alloy considerably improved the working

Jan 1, 1929