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By R. W. Leonardson

Tectonic activity in northern New Mexico during late Oligocene and early Miocene time presaged events which led to the development of molybdenite deposits at Questa. East-northeast directed crustal extension produced north-northwest striking tensional fracture systems paralleling the early Rio Grande rift. A sequence of Oligocene andesite flows and breccias is overlain by a thick early Miocene rhyolite ash-flow tuff. Eruption of the tuff initiated collapse of the Questa cauldron: the south margin of which occurs as an east-northeast striking, north-dipping structurally weak zone. Continued east-northeast post-cauldron extension permitted the high level emplacement of granite stocks with coeval rotational deformation of fault blocks composed of cauldron fill and [ ] floor. The stocks occupy north-northwest fracture zones in the south margin of the cauldron, and porphyry dikes occupy east- northeast striking faults that define the south margin. These two fracture systems have played a dominant role in localizing the intrusive porphyries and associated mineral deposits at Questa. A molybdenite-bearing breccia matrix and related stockwork mineralization generally occur within volcanic rocks. Mineral deposits are spatially related to fault zones and the upper con- tact of their source intrusives. Deposits are localized in fault zones up to several thousand feet long and 100 to 500 feet in diameter. Magmatic-hydrothermal solutions from the source aplite porphyries have produced potash metasomatic alteration which is strongly centered on the mineral and ore zones. Alteration in ore is represented by orthoclase, quartz and secondary biotite. This pattern grades into secondary biotite and propylitic zones forming successively weaker alteration assemblages away from ore. Younger phyllic and argillic assemblages are particularly widespread only where strong north-northwest extensional fracture zones cross the south cauldron margin.

Jan 1, 2013

By A. A. Schweizer

Buckhorn ore is hydrous, argillized basaltic andesite, and is at least 60% clay composed of kaolinite and subordinate montmorillonite. Moisture content runs from 10% to 25%. The original crushing plant was a typical compression type, employing a jaw crusher, and two cone crushers. The system was plagued with constant plugging and unable to meet production plans. The three compression crushers were replaced with a Stamler Feeder Breaker followed by a Hazemag Impactor. Production plans are now exceeded. Agglomeration has progressed from an agglomeration drum to cascading conveyors, to introduction of the lime and cement into the primary crusher.

Jan 1, 1987

By Ruipeng Qian, Pengfei Wang, Guorui Feng, XianJie Du, Jun Guo, Yuxia Guo, Tingye Qi, JinWen Bai

"A numerical modeling was conducted to describe the behavior of overlying strata on the longwall top coal caving face for exploitation of a 16.8 m thick coal seam. Three typical structural models, including the Cantilever Structure (CS), Lower Cantilever and Upper Hinged Arch Structure (LC&UHA), and Lower Arch and Upper Voussoir Beam (LA&UVB), were developed. Based on mechanical analysis of the different structures of the key strata, and considering the behaviors of the broken igneous rock strata, a method was proposed and applied to estimate the structures of the overburden strata. The results had been verified by a field micro-seismic monitoring test. The paper provides a foundational method to determine the shield loadings for the top coal caving longwall face.INTRODUCTIONLongwall top coal caving (LTCC) is a highly productive underground mining technology which has been widely applied to the exploitation of the thick coal seams in China and other countries due to its high efficiency (Ju and Xu, 2013; Ju, Xu, and Wang, 2011; Liu et al., 2009). In recent years, a large amount of research on mining pressure forecast, strata control, and mechanical equipment improvement of the LTCC technology has been carried out, which greatly advances the field application of the technology (Liu et al., 2009; Yu, 2016; Dou et al., 2014; Feng et al., 2011; Chen and Li, 2011; Yin, Yan, and An, 2008). In 2006, the LTCC technology was first applied to the exploitation in a 20 m thick coal seam at the Tashan Coal Mine in China (Yan et al., 2011). Ten years of mining at the Tashan Coal Mine has highlighted the importance of the support management in controlling the roof strata on the extra-thick LTCC face. The mining pressure is closely related to the structural features of the overlying strata and its movement laws (Yu, 2016; Dou et al., 2014; Feng et al., 2011). However, the distributions of three zones—caving zone, fracture zone, and deformation zone—on the fully mechanized caving longwalls changed significantly with the increase in thickness of the coal seam (Chen and Li, 2011). The behavior changes of the roof strata led to abnormal pressure in the mining face and resulted in the difficulty of surrounding rock control (Yin, Yan, and An, 2008; Liu et al., 2009; Yan et al., 2011; Gong and Jin, 2008). Therefore, the theoretical research focused on the behavior of overlying strata to reveal the laws of mining pressure has important theoretical significance and practical value.Many classical studies (Qian and Shi, 2003; Feng, 2010; Yu, 2015; Yu, Yan, and Liu, 2012) had been done to describe the behavior of overlying strata in the mining process. It has also been reported that magma intrusion causes an important effect on the surrounding rock, coal, and methane (Wang et al., 2005; Liu et al., 2007). On the one hand, the property and structure of the coal seam was obviously changed by the magma intrusion and resulted in a potential danger of a gas outburst during the mining process (Chen et al., 2012; Wang et al., 2014). On the other hand, the hard igneous strata and the joints occurred with the magma cooled, causing an abnormal behavior of overlying strata and resulting in a series of dynamic disasters during mining (Xuan, Xu, and Lu, 2014; Lu et al., 2016). In fact, many coal fields in China are intruded by igneous sill, including the Datong, Shuozhou, Huainan, and Xuzhou coal fields (Chen et al., 2014; Wu, 2011). The 3–5 coal seam at Tashan Coal Mine in Datong coal field is very thick and is intruded by a large area of layered lamprophyre rock. Face falls and shield failures occurred frequently during the face retreat."

Jan 1, 2019

By Ian Sheppard, Kugan Kuganathan

The Mount Isa Rocky Paste Fill (RPF) was one of the five fill options investigated for the Enterprise Mine filling between June 1996 and September 1996. Co-disposal of deslimed cemented tailings (CHF) and suitably graded rockfill (RF) in certain ratios produced the rocky paste fill. The RPF behaved like a cohesive paste with very high proportion of rockfill in the mix. Several large-scale mixing trials and drop tests proved that the rocky pastefill results in a homogeneous fill mass after placement. Segregation of RF was a common problem with MIM's traditional cemented rock fill (CRF), which is a combination of CHF and RF. The segregation was eliminated and a non-segregating paste like fill was created by optimising the particle size distribution of RF, and combining the RF and the CHF in optimum ratios. In rocky pastefill, the excess water in the cemented deslimed tailings slurry is taken up by the rockfill as the surface moisture on the rockfill particles and also as pore water between the particles. This results in thickening of the CHF, and the resultant mix is a non-segregating cohesive paste, which can easily spread to any horizontal distance inside a stope at a very low surface angle. The rocky pastefill releases no free water and relatively more pervious than the standard CHF due to rockfill component. With an average cement addition of 1.5 to 2% the rocky pastefill can develop higher strengths over 1Mpa. The rocky paste fill is applicable in many situations and can accommodate a variety of coarser materials that would be available in different mine sites. This paper present the research work and the experience associated with the rocky paste fill, and gives clear design principles for any potential users.

Jan 1, 2001

By Jamal Rostami, Manso Deen Sesay, Sydney Slouka, HUGH MILLER, Anshuman Mohanty, Midhat Sajad, Kun Zhang

The lack of progress in controlling pulmonary diseases such as pneumoconiosis cases in recent years necessitates additional studies on dust generation and the characterization of airborne dust. Studies are underway by a NIOSH-sponsored project to observe the characteristics of the dust generated by pick cutters under various wear levels. This research performed a full-scale linear-cutting-test matrix on eight coal samples with various bit penetrations, spacing, and wear conditions. The specific energy and resulting PSD (particle size distribution) of airborne dust and material left at the cutting surface were measured and analyzed. The dust concentration was determined using the NMAM (NIOSH Manual of Analytical Methods) 0600 method. For fines, the PSD was characterized using Laser Diffraction, measuring percent channel and aerodynamic diameter, while Imagej, a virtual sieving application, was used for larger particles. The results show that for a new bit, as the cutting depth and spacing increase, the specific energy and dust generation decrease. The size and shape of the dust particles have been analyzed, and the observed trends are discussed in this paper.

Feb 1, 2025

By Georgene Renner

With more than 800 booth spaces sold and 540 exhibiting companies displaying their wares, there was something for everyone on the exhibit floor of the 2014 SME Annual Meeting in Salt Lake City, UT Feb. 23-26. The following is a sample of what was offered at the 2014 meeting.

By Laszlo Toth

A feeder is used to control the gravity flow of bulk solids from storage areas, like a bin or a stockpile. For this type of application, it is important to select a proper drive that can fulfill all of the demands put on it. High starting torque capacity, variable speed and the ability to handle frequent starts and stops are some of the demands that the drive must be able to meet. The following is a comparison of the most common type of drives used today for feeder applications. When a feeder is started, the breakaway torque may reach as high as200% of the running torque. The accelerating torque usually is set to protect the carrying element of the feeder, like the belt for the belt feeder and the carrying chain of the apron feeder (Fig. 1).

Jan 1, 2003

By D. M. Carris

Since the Buffalo Creek incident in February, 1972, Federal and state environmental agencies have had the pressure on the coal industry in the Appalachian area to close the coal processing plant water circuits. In an attempt to comply with this requirement, Eastern .Associated Coal Corp. decided to install a vacuum disc filter system at its Kopperston plant to eliminate the tailings pond and reduce the amount of plant make-up water. It was recognized at the time that the plant static thickener tailings would be a very difficult slurry to dewater because of its unusually high clay content. The following is a case history of the Kopperston installation and the refinements Eastern has made in its vacuum disc filter operation to increase efficiency.

Jan 1, 1979

By D. Babich, L. Alcorn, E. Spencer, A. Smith

Noise is one of the most pervasive health hazards in mining. A compilation of Mine Safety and Health Administration (MSHA) noise survey data for Fiscal year 1990 shows that approximately 40% of the total samples taken for longwall occupations exceeded the Permissible Exposure Limit (PEL) of 100% [Gigliotti et al. 1991]. In order to properly determine workers’ exposures on longwall coal mining systems, it is necessary to provide accurate baseline measurements for these mining systems. This research was designed to develop guidelines and test procedures for identifying all noise sources that are major contributors to the underground noise exposure of longwall coal mining system workers. Once the high noise sources are identified, promising engineering controls can be tested and evaluated to reduce the noise of the sources. The measurement system used to analyze the noise sources included stationary dosimeters in a documented repeatable pattern and a time-motion study of the cutting cycle and operator’s work cycle. Significant results from the underground measurements show that the highest sound levels recorded are at the stageloader discharge segment and tailpiece controls and remained at about the same level throughout the test.

Jan 1, 2007

By M. N. Semenoff

On July 8, 1999, EPA announced the RCRA Cleanup Reforms, a set of administrative reforms designed to achieve faster, more efficient cleanups. This paper will discuss the Reforms, the status of their implementation and assess these potential impacts on the mining industry.

Jan 1, 2001

By Gary E. McIntosh

This paper will discuss a U.S. Bureau of Mines project designed to assess and predict the impacts which surface coal mining will have on the regional shallow groundwater systems in the Powder River Basin. The primary objective will be met through the accomplishment of the following: (1) The design and establishment of a regional network for monitoring of shallow groundwater systems in the Basin. (2) Monitoring of the direction and rate of flow, water quality, and aquifer characteristics of the shallow groundwater systems. (3) Development of a regional groundwater simulation model with appurtenant subroutines to determine local effects.

Jan 1, 1978

By P. Perruzza, R. Grandori, A. De Biase, A. Ciamei, A. Busillo

The Turin metro alluvium soil is mainly made of large boulders, cobbles and gravel , few sand and almost no fines. This grain size curve is out of the range of application for EPB and Slurry TBMs. In order to bore 5 of the total 7,5 kms of Line 1 tunnel, two specially designed Lovat EPB TBMs were utilised in combination with a systematic non structural pre-grouting of a small volume rectangular slab just above the tunnel section. The same pre-grouting was not however applicable for lack of access on surface in some sections of the remaining 2,5 km of tunnel that had to be bored below important buildings/structures, with under ground water pressure up to 1,5 bar, with curves radius of 180 m only. For these more critical sections it was necessary to study and implement a new technical solution and improve the capacity of the TBM to work efficiently in EPB mode even in this unsuitable ground and overall conditions. After months of studies the selected and adopted solution has been to inject inside the cutterhead chamber, in addition to the almost standard foams & polymers additive mixes, a suspension of limestone powders. This with the scope of compensating the lack of fines of the natural ground with rock powders.

Jan 1, 2005

By Luke Erickson

San Francisco Public Utilities Commission is planning to replace 5 miles of pipeline under San Francisco Bay. The tunnel will be constructed using an Earth Pressure Balance (EPB) TBM and will be the first TBM-driven tunnel under the Bay. The alignment passes under environmentally sensitive habitats, through interbedded layers of sands and clays, and through a buried bedrock ridge. This paper discusses the geotechnical characterization and anticipated tunneling conditions and presents the analysis of various construction methods that resulted in the selection of an EPB TBM. Considerations related to tunneling with an EPB TBM are described in detail, including ground conditioners, TBM cutterhead wear, muck control, and squeezing ground.

Jan 1, 2008

By Sheridan A. Glen

As the Federal government along with individual states continue to grapple with the job of refining a comprehensive energy policy, coal continually stands out as an energy source which heralds a combination of old and new capabilities like an energy planners prophecy, but which is plagued with serious environmental constraints. To determine what level of coal utilization is ultimately possible for states East of the Mississippi, whose high sulfur content coal presents the most paramount of challenges, one must consider product availability, via existing transportation modes, the developing industrial markets and the ability of coal to meet the challenge of becoming an environmentally acceptable fuel. Gasification is emerging as a form of utilization, which during the next twenty years stands a good chance of being able to meet the challenge of making coal an environmentally clean, easily transport-able and usable fuel. It can be argued that, of all the potential ways of utilizing high sulfur coal, coal gasification is perhaps the most expensive, the most financially risky and carries environmental liabilities of its own. Synthetic gas and oil markets will undeniably be a function of price and demand, which, for the purposes of this paper, I'm assuming will begin to merge in the late 1980's and into the 1990's. This is also presuming that public utility commissions will allow favorable price structure ruling so that gasified coal products can be rolled into their respective rate base, much the same as synthetic natural gas from petroleum by-products are currently being priced. The comparative economic markets of coal to gas pro-duct have plenty of time to mature. There is an approximate twelve-year lead time needed to bring coal gasification plants on line which will be able to compete in the market place for natural gas and oil customers.

Jan 1, 1977

By William Gleason

"The times they are a changing, and, for the mining industry, the optimism is high. On Nov. 8, Donald Trump was elected as the 45th president of the United States, and the Republican Party won a majority of seats in the U.S. Senate and the House of Representatives, ushering in what many hope will be a positive change for the mining and extractive minerals industries.Trump has stated that one of his top priorities as president will be to increase spending on the nation’s infrastructure, which could help spark a boom for mining. He has also pledged to bring back coal jobs and reverse many of the environmental regulations that were put in place by the Obama administration. However, before the mining industry gets too far ahead of itself and plans for another Super Cycle, there are stark reminders that any work in the natural resources sector is complicated and challenging. On Dec. 4, the U.S. Army Corps of Engineers announced that it would not grant an easement that would allow the Dakota Access Pipeline to pass under a portion of the Missouri River in North Dakota. The proposed crossing of the oil pipeline is approximately a half a mile upstream from the Standing Rock Sioux’s Reservation, and for months, hundreds of protestors camped out at the site in an effort to halt the project, saying they feared how it would impact water supplies and sacred lands.Energy Transfer Partners, the company building the pipeline, said the pipeline is a $3.78-billion investment that will connect the Bakken and Three Forks production areas to major refining markets. The company signed voluntary easement agreements with landowners representing more than 85 percent of the properties along the four-state route but faced an organized protest from the Sioux Nation at Standing Rock. The protest gathered momentum and support through social and traditional media and became the focal point of global environmental and indigenous activism. The protestors claimed victory, at least temporarily, when the Corps of Engineers said it would look for alternative routes for the project. It’s a decision that could lead to a lengthy environmental review and one that has the potential to block the construction of the pipeline for months or even years."

Jan 1, 2017

By Y. Okahara

The chlorination behaviors of pure iron and manganese oxides were investigated by combining a thermogravimetric analysis (TGA) technique with batch-boat roasting followed by leaching. Ferrous and manganeus oxides could be chlorinated readily, but, in the absence of a reductant, the higher oxides of both iron and manganese were difficult to chlorinate. Thermogravimetric analysis curves were drawn to illustrate the complexitites of the reactions, and the possible mechanisms were discussed. Then three manganiferous materials from the Cuyuna Range of Minnesota were treated by a process involving the selective chlorination of manganese followed by leaching. The results were interpreted in the light of the chlorination mechanisms observed on the pure iron and manganese oxides.

Jan 1, 1969

By L. B. McConville

The general term "tar sand" has been used to describe sand containing varying amounts of dense, viscous petroleum. Deposits of tar sands have been found throughout the world, often in the same geographical area as conventional petroleum. The largest one by far is known as the Athabasca Tar Sands, and is located in the province of Alberta, Canada. Actually a group of three deposits, these particular sands underlie an aggregate area of more than 12,000 square miles. Current estimates place the contained raw petroleum at about 700 billion barrels, from which as much as 300 billion barrels of synthetic oil may be recoverable under presently developed technology. For comparison, this latter quantity is roughly equivalent to five times the combined total of U.S. and Canadian crude oil reserves. With the ever-widening gap between energy supply and demand, attention is being directed to all possible energy sources - both developed and underdeveloped - and certainly the Athabasca Tar Sand deposit is one of the more important ones to merit such attention. This paper will review some of the more significant developments and attempt to place in perspective the role that this source of energy could possibly be expected to play in the foreseeable future.

Jan 1, 1974

By Brianna M. Eiter, Jennica L. Bellanca

Mineworkers face a challenging and dynamic work environment every workday. To maintain a safe workplace, mineworkers must be able to recognize worksite hazards while they perform their jobs. Though hazard recognition is a critical skill, recent research from the National Institute for Occupational Safety and Health (NIOSH) indicates that mineworkers fail to identify a significant number of hazards. To further the understanding of mineworkers’ hazard recognition ability and to begin to address hazard recognition performance, NIOSH researchers analyzed data collected during a laboratory research study to determine the effect of individual mineworker factors including risk attitude, work experience, and safety training on hazard recognition accuracy. The results of this study show that mineworker risk attitude and safety-specific work experience affect hazard recognition performance while hazard-specific safety training does not. These results suggest that some of these individual factors can be overcome through experience and training. Potential strategies that can be used to address these factors are also discussed.

Aug 31, 2020

By Fahimeh Dehghani, Louis Ackah, Tathagata Ghosh, Justin Godbold, Jia Liu, Meisam Peiravi, Manoj Mohanty, Azam Baharlouei

Primary economical deposits of rare-earth elements (REEs) are exhausting all over the world, and it has become necessary to find new sources and methods for their extraction. In addition, increasing the application of REEs in modern technological society has increased its demand globally. One of the important movements to compensate for the future shortages of critical metals is the recovery of REEs from recyclable materials. This paper presents a review of the classification and extraction methods, as well as general applications of REEs with emphasis on secondary sources such as coal and coal byproducts, iron ore tailings, apatite, and phosphate byproducts. An overview of the current state of knowledge on the various methods of REE beneficiation and extraction is covered. These methods include physical separation, as well as hydrometallurgical and bio-hydrometallurgical techniques. The application of these REE extraction techniques for enhanced recovery has been driven primarily by the unique industrial application of these important elements. This paper further explores the existing and potential environmental challenges associated with REE extraction. The authors have presented a wide array of literature, in-depth discussion of the subject, and a succinct summary of processes and relevant case studies.

Sep 23, 2020

By Frederick McNeill, John Harper, Mahmood Khwaja, Shawn Lavoie, Timothy Cloughert, David Polcari

City of Manchester, NH, is implementing a 20-year plan to control and significantly reduce overflow of its sewer system. The long-term control plan had called for large scale box culvert installation through downtown Manchester. The City and the project team evaluated, and eventually selected, tunneling as an alternative to mitigate construction related impacts for open trench approach. This paper provides an overview of the alternative evaluation process; discusses the development of the preliminary design for the 12,000 feet long, 12-ft internal diameter tunnel, including plan and profile selection, subsurface conditions, drop shafts and the anticipated packaging of the separation areas.

Dec 1, 2022