Search Documents

By Liane L. M. Kacinuck

This U.S. Bureau of Mines publication is intended to provide mining industry representatives and regulatory authorities with a reference package dealing with studies on hydrology and underground mine subsidence. An annotated bibliography and a list of additional sources are given and represent references published prior to June 1993. Ninety-two references ware identified and 72 obtained for assessment. Annotating the references included evaluating the study methodology and summarizing the basic results. The references are also compiled based on geographic location to aid the user in identifying articles of particular interest.

Jan 1, 1994

By T. Mal

A test system was developed at the National Institute for Occupational Safety and Health's ventilation test gallery for measuring airflow using a three-axis ultrasonic anemometer. The gallery war used to simulate face airflow conditions in underground mines having a blowing curtain. Airflow data, collected at multiple sampling locations between the face and the end of the curtain, were used to draw airflow profiles for different curtain setback distances, intake flow quantities and entry widths. In addition, methane was released at the face, measured at the sampling locations and displayed as methane distributions in the area between the curtain and the face. Entry geometry had a significant effect on airflow patterns, and the flow patterns affected the distribution of methane in the entry. Flow measured at and parallel to the face was a good predictor of methane dilution and removal within 0.6 m (2ft) of the face.

By S. Kariyawasam, R. McNealy

Pipelines are subject to multiple threats often requiring quantification of pipeline risk and engineering evaluation of in-line inspection and other data to effect discovery of conditions defined by the regulation. Public concern and pressure from regulatory bodies are accelerating the need for pipeline operators to formalize and intensify their approach to integrity management. Most operators need a phased approach to progressively adopt the most relevant and needed assessments. The organized and relevant assessment steps need to be introduced according to data available and maturity of the integrity management program. Each refinement to the quantification offers distinct advantages to the user. In this paper, the progressive integrity assessment solutions using quantitative methods are presented. Methodologies for engineering evaluation of integrity in-line inspection data for immediate and future integrity are summarized. Corrosion is used as an example, but the approach is applicable to any time-dependent defect based hazard. Strategies for pipeline integrity management are discussed.

Jan 1, 2005

During August, 1926, with the consent of Mr. Schell, mine manager, the writer conducted a mill test on this company's concentrators. Mr. Schell not only gave him his permission, but rendered all possible assistance. Although it was impossible to take all the samples one could have wished to obtain, yet the salient points of the mill flow-sheet were sampled for a continuous period of eight hours, and from these samples and separate data supplied by the manager, valuable information was collected.THE MINEThis is a true vein-type of mine; the lode formations, striking almost due north-south, cut the large porphyritic intrusion at right angles. There are three distinct veins on this property - parallel, persistent, and dipping at an angle varying between 40° - 50° to the horizontal.The country rock is very sound, and timber, save for the small amount required for ore chutes, is entirely absent from all mine workings.The lode varies from a width of 1 in. to 8 in., but the stopes are carried forward with a minimurn width of about 30 in.The mine is particularly dry for a West Coast property, and conditions underground are very favourable. Air drills are used...

Jan 1, 1928

By R. Lee Wooten, David R. Shields, Darren D. Clark

"Borehole permeability tests that measure flow or head changes in boreholes located within seepage barrier walls are commonly used to estimate the in situ permeabilities of those walls for quality control and assurance. The current state of practice for estimating permeabilities from these barrier wall borehole tests is to use equations published by M. J. Hvorslev in 1951. Hvorslev’s borehole test equations model an infinite stratum of uniform permeability, which is not the actual condition for a test performed in a low permeability barrier wall located within a high permeability stratum. We examine and develop alternative equations based on line source analytical models, which more closely match barrier wall test conditions. We describe how these alternate equations can be used to estimate barrier wall permeabilities from borehole tests and compare the results to those obtained from the Hvorslev models. We also provide recommendations that consider differing upstream and downstream water levels.Barrier Wall Permeability Tests - State Of PracticeThe installation of seepage barrier walls has become more common in a variety of applications ranging from dams and levees to contaminated sites requiring retardation of groundwater flow. The types of seepage barrier walls and installation methods include soil-bentonite, soil-cement-bentonite, concrete, self-hardening slurry, geomembranes, and sheet piles, installed with various soil mixing, slurry-supported trench, and driving methods.Owners and contractors have used a variety of methods to evaluate the permeability of these seepage barriers. The following table lists commonly used quality control/assurance tests for evaluating the permeability of a seepage barrier."

Jan 1, 2016

By Y. L. Tian

Low-grade bauxite with A/S of 4.4 from Henan province was used as raw material and the selec-tive grinding of bauxite, grinding efficiency, particle size and Al2O3 and SiO2distributions of ground products were investigated using ball and vibration mills. The results show that the selective grinding can be used to realize the separation of aluminum from silicon within a certain particle size. The optimal grinding conditions of the ball mill with bauxite are as follows: grinding material to charge ratio, 1.2, charge volume ratio, 40%, pulp con-centration, 70wt%, medium size distribution, F30mm:F20mm:F15mm=20%:50%:30%. Under the conditions, the weight rate of ground product with A/S over 7.5 is 27% and the recovery of Al 2O3is 30%. The optimal grinding condition of the vibration mill with bauxite are as follows: grinding material to charge ratio, 0.9; charge volume ratio, 70%; concentration, 70%; medium size distribution, F40mm:F30mm:F20mm=20%:30%:50%. Under the conditions, the weight ratio of ground product with A/S over 7.5 is 25% and the recovery of Al 2O3is 27%. The research is significant for the rational and economical utilization of the low-grade bauxite.

Jan 1, 2014

By Charles Barnhart

This paper is a discussion of the causes of deflagration in cast blasting and a description of a project intended to demonstrate how changes in six critical parameters contribute to the deflagration chemical reaction. Control of these parameters is key to solving the nitrogen dioxide “orange smoke” problem. Preliminary results of an investigation into the development of a technology addressing the problem of atmospheric releases of nitrogen dioxide during cast blasting in surface mine operations are described. The project is funded by a $600,000 Small Business Innovative Research grant from the National Science Foundation and an $80,000 Abandoned Coal Mine Land Reclamation Program grant from the state of Wyoming. The presentation will address the measures required to control the blast chemical reaction so that it does not produce nitrogen dioxide through deflagration. Experimental blast data will be focused on a new shaped charge detonation system designed to instantaneously bring the powder column to maximum velocity of detonation (VOD), thus insuring efficient detonation of the entire colulnn.

Jan 1, 2003

By Qi Wang, Zengzhu Kang, Jianguo Liu, Guanglei Liu

"Due to the increase of automotive vehicles, available parking spaces become a new type of limited resource in central cities of China, especially in those old districts without visionary urban planning. Additional mechanical parking in underground space is an efficient solution to provide parking spaces under the situation where the urban space is constrained. Shichahai district is an old protected zone in Beijing which is close to the Forbidden City and there are many Hutong (alleyway) and Quadrangles (courtyard house). No spaces are available for car parking on the ground and all vehicles are parking in Hutong without order currently. The local government plan to do renovation work for this district and improve the residential environment. Several innovative solutions are studied including parking in deep shafts, parking under existing buildings by under-pinned method, parking under buildings by covered excavation method, parking under roads built together with utility tunnel etc. 5000 difference types underground parking spaces are planned to be constructed in the following three years. Project examples are also introduced in this paper. INTRODUCTIONCar parking resources are very limited in central cities, especially in old districts without planning for increasing automotive vehicle volume. Traffic get worse when cars park on the side of the roads or move slowly to find parking spaces. Investigation shows the normal (parking space/ automotive vehicle volume) ratio is about 1.2 in most big cities such as New York, Tokyo and Hong Kong, while this ratio is only 0.5 in Beijing. One solution is to move cars out of central cities. But there are still huge parking requirements for the citizens living in central cities. Shichahai district is an historic protected zone in Beijing which is close to the Forbidden City and there are many Hutong and Quadrangles (refer to Figure 1 for project location). No spaces are available for car parking on ground and all vehicles are parked in Hutong without order currently. The local government had a plan to do renovation work of this district and improve the residence environment. 5000 different types of underground parking spaces are planned to be constructed in the following three years. One project designed and to be constructed by Zhongyan Technology will be introduced in this paper. Other innovative solutions will be introduced briefly as well."

Jan 1, 2017

By using knowledge-based technology to create a Virtual Mining Enterprise and integrating it with existing technical and financial computer systems, a gold mining company has been able to reduce the time taken to produce a mine plan from 14 weeks to less than one week. Typically, the mine planning process requires circulating and managing large amounts of information. Even with the use of computers in todayÆs business, this is often still a manual process involving file transfers and individualised spreadsheets. Mine planning also involves understanding and managing large quantities of complex and interrelated variables. Added to this is the ever changing dynamics and constraints associated with the business of mining. These issues not only hamper the planning process but also question the validity and usefulness of the mine plans being generated. By integrating the information and knowledge of the numerous departments involved in mine planning into one core Knowledge Base - so called æone version of the truthÆ, - mining companies are able to overcome these pitfalls experienced in traditional planning methods. Once set up, the Knowledge Base creates and runs a virtual mining enterprise with which to visualise and test various scenarios of mining, business and logistical activities. The final output is an optimised enterprise-wide plan with clear and detailed instructions for each of the divisions of the company.

Jan 1, 2000

By D. E. Pollock, T. W. Beck, J. A. Organiscak

This work presents the findings from a number of NIOSH studies evaluating the impacts of emerging technologies that may reduce dust exposures for continuous mining and roof bolting personnel. These technologies include use of a wet head cutting drum on a continuous mining machine that places water sprays on the cutting drum instead of placing them on a manifold outby the drum. Evaluations at two separate operations showed that the use of the wet head sprays reduced dust levels at the miner operator in the return air, although these reductions were quite variable. NIOSH also assessed the effectiveness of a canopy air curtain for protecting roof bolting personnel. The data showed that dust levels were lower beneath the air curtain than outside the air curtain. This study also suggested several future modifications to the air curtain to in-crease its effectiveness. Finally, NIOSH evaluated mist drilling technology for its effectiveness in controlling respirable dust exposures of bolting personnel. A recent study showed that higher dust levels existed around a machine using the mist system compared to a machine using a conventional vacuum system for dust control. Unfortunately, the true impact of mist drilling was confounded by this machine operating downwind of the continuous miner for much of the study.

By S. Lähteenmäki, P. Koivistoinen, J. Levanaho

Semi Autogenous Grinding (SAG) circuit is the most common grinding circuit to day. In Europe and South Africa fully autogenous (AG) circuits are also popular. SAG circuit has a lower capital cost and simple operation. SAG circuit requires the use of grinding balls, which increases operating costs and decreases availability. An AG circuit may produce a higher Net Present Value to the investment. The AG circuit is more complex to design and operate. However, operating experience from AG circuits illustrates that an AG circuit can be as trouble free as a SAG circuit with the benefit of lower operating cost.

Jan 1, 2001

By A. P. Whittlestone, J. D. Johnson, R. J. Pine, M. E. Rogers

standpoint. The effect on efficiency of collisions

Apr 1, 1995

By Lian-Jin Tao

With fast development of China modernization, road construction obtains great achievement. However, in the construction process of highway, especially the high-grade highway in mountainous area, there are many unavoidable high cut slopes. Specifications for Design of Highway Subgrades, China, prescribe that the design scheme of slope with height more than 30m should be compared with bridge scheme and tunnel scheme economically. In spite of the existing guidelines, it is still quite common to see many high slopes due to engineering geological conditions, highway line shape, cost and issues related to traditional design ideas. Actually the traditional way with ?high backfill, the high cut? for mountainous highways seriously damages the original ecological environment and groundwater system, especially to those area with weak ecology, where the damage is unrecoverable. It is quite common practice to use artificial vegetation for cut slope virescence, however it still has problems such as low ratio of survivor, high maintenance cost and lack of species diversity. Now people are more and more aware of the importance of ecological environment, it becomes urgent to decrease the damage to ecological environment after ensuring the stability of high slopes. With the aim to reduce ecological damage, we proposed a new design approach which is ecological environment friendly by decreasing cut slope height with steep excavation scheme. This approach requires that (1) the geological condition is good, and the rockmass can be sTable itself; (2) excavation should not badly damage the rock, which means blasting must be controled by using buffer blasting, smooth blasting and pre-splitting blasting; (3) if local geological condition is not very good, excavation should have intervals for one bench, the advised space is 20m; (4) to ensure the slope stability in construction process, the cut slope should be reinforced more strongly than usual and in time. Finally, the deformation of the slope and the working condition of the reinforcement structure should be monitored to ensure the slope stability. The new design is used to a roadside cut slope of provincial trunk highway S223 in Guangdong Province. Based on intensive geological investigation and borehole tests, it is found that the slope rock mass is intact and sound, and the rock strength is quite high. Results from numerical modeling by UDEC reveal that compared with the traditional design scheme with 90.23m high slope, the steep scheme with only 23.46m high is characterized by its relatively large deformation and stress concentration, however the influenced area only appears at the upper slope and tends to sTable. With cable reinforcement, the stability of slope excavated steeply can be guaranteed. Deformation of the slope and the cable force are monitored in details in the period of construction, which show that the deformation of the slope decreases gradually and the final deformation is very small, and the cable tensions change small after the cables were tensioned. It is optimistically estimated that the steep slope should be sTable during operation. Comparison analysis between the steep scheme and the common scheme affirms that the steep excavation is better than the traditional scheme in terms of ecological environmental effect, slope height, the excavated amount, the excavated quantity of slope surface, engineering cost. It is concluded that if geological condition permits, the steep cut scheme should be used with better benefits.

May 1, 2009

By E. Hornbogen

The deformation mechanisms of a iron-phosphorus alloys were compared at 20oand —196°C. Alloying with phosphorus increases the resistance to slip, but has little effect on the resistance to twinning. The stress for onset of twinning is nearly independent of temperature, but there is an increasing tendency for cleavage along (112) twin boundaries with decreasing temperature and increasing phosphorus content. FIVE iron-phosphorus alloys and one high-purity iron (0.004 pct C, 0.004 pct N, 0.05 pct O) were vacuum melted and cast, then homogenized for 6 hr at 1100oC and water-quenched. Single crystals were cleaved from the coarse grains produced in this manner. The hardness was measured* on polished (100) surfaces of the crystals at 20" and -196°C. Laue back-reflection patterns indicated a deviation of not more than 3 deg from coincidence of the {100} plane with the surface. The deformation mechanisms were studied by relief effects on the polished surfaces. Yield points in compression (0.5 pct offset) were measured with polycrystalline material. At 20°C the addition of phosphorus to a iron leads to a change from slip to twinning as the main deformation mechanism, Figs. 1(a), (b). Between 2 and 4 at. pct P slip and twinning occur simultaneously. In alloys with more than 4 at. pct P twinning is the main deformation mechanism and slip was observed only in the neighborhood of twin intersections. All cracks at 20oC were on (100) planes, some initiated by twins.' From measurements made at-196oC, hardness and yield points of all the alloys were nearly constant and the same as the hardness of high phosphorus alloys that deformed by twinning at 20°C, Figs. 2 and 3. In the high-purity iron, plastic deformation at -196°C occurred by both slip and twinning, but deformation in the iron-phosphorus alloys appeared to be entirely by twinning. In the high phosphorus alloys a large number of cracks formed along the (112) twin boundaries and at intersections of twins, in addition to the (100) cleavage, Fig. 1(c). DISCUSSION In , iron, plastic deformation can occur either by slip or by twinning, depending upon composition,

Jan 1, 1961

By R. V. Ramani

One area of study in the Coal Mine Injury Analysis project was to illustrate and enhance the ability of mine safety management personnel to apply analytical techniques to injury experience data and to justify requests for funds for safety enhancement actions on a cost/benefit and other quantitative basis. Four volumes of this final project report detail (1) the objectives and scope of the mine safety management research, (2) the results of literature review, and case studies, and (3) models developed for mine safety management. The four volumes are titled as Volume III: Mine Safety Management, Volume IV: Analytical Techniques for Mine Safety Management; Volume V: Mine Safety Management Case Studies and Volume IX: Training Cost Model. In this volume, the quantitative procedures that have been developed for the mine-specific analyses of accident/injury experience data are presented and their applications are demonstrated in a summary form through case study examples. The quantitative procedures will aid mine safety management personnel to develop focused accident prevention strategies including training, as well as to justify the investment in such proactive programs through cost-benefit analyses.

Jan 1, 1993

By Charles Pack

Extensive progress has been made in the metallurgy of alloys for die castings. Enthusiastic proponents of some alloys are inclined to make extravagant claims for their materials, which may be justified by physical tests on test bars made from the respective alloys but are seldom justified by the results obtained with commercial die castings made from those alloys. Chemical analysis of the test bars and castings fails to determine the cause of these variations, since they are due to other physical factors entering into the commercial production of die castings. In this paper, an attempt will be made to outline some of the factors in commercial die-casting practice to which these variable results may be attributed, in the hope that the manufacturer of die castings, recognizing the importance of these factors, will devote more attention to them in the design and construction of dies and equipment. In 1914,l the author defined die castings as "metal castings made by forcing molten metal, under pressure, into metallic molds or dies." This definition was given in order to differentiate die castings from other molded metal products such as "permanent-mold" castings, L'slush" castings and similar products that are sometimes erroneously termed die castings. The term "die casting" could be interpreted to include all castings made in metal molds or dies; but since this term, like most of our technical nomenclature, has been developed by commercial practice we must look to this practice for its proper definition. The Germans, with their usual devotion to desecriptive names, have adopted the name of sprilzguss (squirt cast) for die castings. Undoubtedly this name is more descriptive of the die-casting process, where the metal is literally squirted into the die and serves to differentiate this process from other metal mold processes, where the metal is poured into the die. In the earlier paper mentioned, the author also emphasized the fact that the definition given for die castings indicated clearly that the satisfactory operation of the process must comprise three factors, all of which must be considered of vital importance to the successful operation of the die-casting process:

Jan 1, 1931

By D. J. Young

Alloys used at high temperature must resist both creep and corrosion. Design for corrosion resistance is based on the formation of a slow-growing, protective oxide scale by selective oxidation of an appropriate alloy component, usually chromium or aluminium. A successful scale will exclude other corrodents, notably carbon, which can otherwise cause extremely rapid corrosion at high temperatures. Selective oxidation of an alloy component necessarily lowers the concentration of that metal in the alloy subsurface region. Under thermal cycling conditions, mechanical damage to the scale leads to renewed oxide growth and accelerated alloy depletion. Eventually, a point is reached where diffusion of a corrodent into the alloy becomes competitive with the outward diffusion of alloy metal to repair the protective scale. Two examples of alloy failure by carbon attack are considered. In the steam cracking (pyrolysis) process, centrifugally cast tubes of heat-resisting alloy are exposed to a gas stream of hydrocarbon and steam, at a carbon activity of unity. Formation and repair of the surface chromia scale causes alloy depletion, Kirkendall void formation, and subsequent internal precipitation of chromium-rich carbides. Their formation makes chromia scale formation much more difficult, and generates internal stress. Eventually, the tubes fail by creep rupture. In other processes (e.g. steam reforming, heat treatment), synthesis gases are supersaturated with carbon at intermediate temperatures. Once the alloy's protective scale is breached, carbon attacks the depleted substrate. In the case of ferritic alloys, it forms a surface scale of Fe3C. As this scale thickens, the supersaturated carbon precipitates as graphite within its outer regions. The resulting volume expansion causes disintegration of the cementite in a process known as metal dusting. In the case of austenitic alloys, no metal carbide is formed. Instead, carbon dissolves in the depleted metal to diffuse inward and precipitate as graphite within the metal matrix. Again, volume expansion causes disintegration of the alloy, and metal dusting results. Dusting occurs at an extraordinarily rapid rate, and leads to failure by section loss or even penetration.

Jan 1, 2013

By Johnson T, Huynh D

The State Electricity Commission of Victoria is conducting a program of research and development into alternatives to the use of conventional boilers for the generation of electricity from brown coal. The objectives of the program are to reduce the cost of electricity generation and also to improve the thermal efficiency so as to reduce the emission of greenhouse gases and other pollutants. The program presently includes the following four technologies: Hydro-thermal Drying, Direct Coal Fired Gas Turbine, Integrated Gasification Combined Cycle, and Steam Fluidised Bed Drying. The Hydro-thermal Drying process produces a combustible coal-water-slurry fuel which is suitable for use in a coal fired gas turbine. The coal fired gas turbine has the potential to produce electricity at a lower cost than conventional power stations and when combined with a steam cycle, it will also use significantly less coal. The Integrated Gasification Combined Cycle process gasifies the coal, cleans the gas, and then bums it in a gas turbine/combined cycle. This process is being developed in Europe and the USA in order to meet their stringent emission regulations. It offers Victoria cleaner more efficient and cheaper electricity.

Jan 1, 1992

By D. K. Crampton

ON giving thought to the subject of this paper, my first reaction was that many and striking changes have come about as a direct result of the war. However, more careful analysis indicates that few, if any, of these changes can be wholly attributed to it. The actual situation is that all these changes were conceived and most of them at least partially executed in re- cent prewar years, it remaining the role of war to achieve results in a fraction of the time that might normally have been taken, lacking its driving impulse. The further discussion will therefore be with the premise that the individual changes have been greatly hastened rather than directly and primarily caused by any war conditions. Co-operation among copper alloy producers on production problems is agreed to be much worth while. The industry was too long noted for jealousy and secrecy as to equipment, methods, and even materials produced. Gradually, a more open and co-operative policy evolved but even just prior to the war the interchange of ideas was relatively cautious and limited. The need for a great increase in production in record time fostered a more co- operative attitude; exchange of ideas and experience concerning all phases of production increased tremendously to the benefit of the individual participants and thus the war effort, too. This more united effort has undoubtedly led to many specific improvements in process or equipment and these in turn to more rapid and economical operation than could have taken place on an each-for-himself basis.

Jan 1, 1944

By Ethan Steward, Kyle Perry

To test the effects of impact on mine seals, a projectile generator and two seals have been constructed. The projectile generator is a 12-inch (30.5 cm) inner diameter steel pipe with a 4-inch (10 cm) wall, is 8.5 feet (2.6 m) in length, and sealed on one end. Projectiles are propelled by a charge of black powder with a wooden wad and are held in place by foam sabots in the bore. This system, combined with the large bore, allows firing of many different potential projectiles that may be found in an underground mine at a high velocity into the seals.

Feb 1, 2020