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By R. L. Derick

On a regular basis, mine personnel should obtain air samples directly from active underground areas as well as remotely from sealed locations. These samples provide mine officials with data relative to the makeup of the various atmospheres. Should conditions underground change, these results can provide a baseline that can assist officials in determining the extent of change. Relating the concentrations of individual gases to time, applying gases to equations, and examining their change over time are tools that have been successfully used to determine if a heating event exists and, if so, the extent of the emergency. These atmospheric status equations have either been developed for the mining industry or adapted from other industries. They serve as tools to assist personnel in determining the condition of underground mine atmospheres. As long as the problem area continues to be ventilated, certain gases, gas ratios, and equations can be used to determine if a fire exists, what type of material could be burning, and what quantity of coal is burning. Once the mine or the involved section has been temporarily sealed, gases, ratios, and gas-derived equations can assist personnel in determining how conditions within the sealed volume are changing over time. To alleviate potential explosions when fresh air is once again introduced into the sealed volume, equations and a diagram have been developed to predict the likelihood of an explosive atmosphere. Similarly, prior to commencing recovery of a mine or section, equations exist that can assist in determining if the fire will rekindle when air is reintroduced. This paper serves as an overview to remind and/or instruct readers about gas-sampling methodologies and gas analyses to assist in determining the status of underground atmospheres.

Jan 1, 2006

By Charles Pretorius

Electronic Delay Detonators (EDDs) with remote wireless programming and initiation capabilities have been successfully used for almost two years now. This system has been used in blasts mainly in South Africa, but also in South America and other countries in Africa. Initially the industry was slow to accept the idea of remote programming and blasting. The advantages were not fully understood and there were some safety concerns. With close to 200 successful blasts as a reference, a much better understanding exists. The advantage of such a system becomes even more significant when the programming of the detonators is digitally integrated with the blast design software as used by the Blast Engineer. It is now possible to import a survey file into the blast design software, to do the blast design using actual hole positions and to then export the designed firing times directly to the detonators down the hole via remote wireless communication. Mines that have been exposed to this technology favour it to the extent that wireless centralised programming is becoming the norm against which other electronic delay detonator technologies are measured.

Jan 1, 2005

By L. C. IlsLey

"During the last eight years there has been a noticeable increase in the use of permissible equipment in gassy and dusty coal mines. This trend has undoubtedly been toward greater safety in mining, but in spite of this all is not well ""along the front.""In many mines those in charge, either through ignorance or supposed economy, have neglected to install sufficient copper and maintain good bonding on the rails used for return circuits to have a safe working voltage for the permissible equipment which is intended to afford them safety.Low voltage, when properly analyzed, is not economy but frequently is an expensive oversight. Burned-out armatures, controllers, rheostats, and switches are costly in themselves to repair or replace, but the greatest cost in many instances is the loss of production resulting from idle and broken-down equipment.From a safety standpoint, excessive low voltage where permissible equipment is necessary is almost criminal negligence. A burn-out of any kind is liable to cause an arc that may burn its way through a casing wall and bring about a hazardous condition if gas or dust in explosive proportions should be present. Again, all wiring, both interior and exterior to the apparatus, is subject to the extra heating consequent upon low voltage. It should be remembered that if the voltage drops the current must increase a corresponding amount in order that the same work may be accomplished; and as the heating effect is as the square of the current, an enormous overheating of the electrical parts and wiring often takes place. This heating effect is especially detrimental to trailing cables used on portable equipment, because under the most favorable conditions the size of cable selected is only barely sufficient to do its work properly at a safe working temperature; therefore, when the extra current load is added because of poor voltage, overheating is sure to result, with consequent deterioration of the insulation, This effect greatly increases the liability of cable failures in service, and in turn adds to the hazards incident to the use of portable equipment of the permissible type involving the use of trailing cables.Some manufacturers have tried -to protect their equipment from low voltage, especially below a certain point, by -installing low-voltage relays which will trip when the voltage falls to a predetermined value. It is understood that some operators have hesitated or refused to install such low-voltage protection because they were aware that the voltage conditions were so poor that the equipment could not operate under the safe limits set. It is difficult to understand how any progressive company that is willing to go to the ex-pense of installing permissible equipment could be so shortsighted in this phase of common sense, safety, and economy."

Dec 1, 1929

By R. Romano

Some topics, which difficult the effective use of RMR for dam foundations, are reviewed and a new geomechanics classification system, DMR (Dam Mass Rating), is proposed -as an adaptation of RMR- giving guidelines for several practical aspects in dam engineering and appraisal of dam foundation. On revise quelques problems qui ont fait difficile l’application du RMR pour les fondations des barrages. On propose un nouveau classification système, DMR (Dam Mass Rating)-comme un désarroi du RMR-qui donne recommendations pour quelques problèmes pratiques dans le projet et construction des barrages, et de ses fondations. Es werden einige die praxisgerechte Nutzung des RMR (Rock mass Rating) erschwerende Themen betrachtet und ein neues Geomechanisches Einteilungssystem, das DMR (Dam Mass Rating), eine Anpassung des RMR, vorgeschlagen. Daraus resultieren neue Richtlinien für verschiedene praktische Aspekte beim Dammbau und bei der Beurteilung von Dammunterbauten

Jan 1, 2003

By Margareth Almeida Dellamore Pacheco

Devido à carência de tarugos de alumínio 6060 com boa qualidade e baixo custo de produção no mercado de extrusão do Brasil, surge a necessidade de encontrar soluções práticas que resultem em um melhor desempenho das ligas na indústria da extrusão. Este trabalho, portanto, tem o objetivo de estudar a influência do tratamento térmico de homogeneização e da taxa de resfriamento pós-tratamento na microestrutura de uma liga de alumínio 6060, assim como as suas implicações na indústria de extrusão. Tarugos cilíndricos da liga de alumínio 6060, com diâmetro de sete polegadas, foram fabricados e submetidos a diferentes ciclos de tratamentos térmicos em um forno industrial do tipo bambury com a finalidade de dissolver e homogeneizar as partículas de segunda fase na matriz de alumínio. As variáveis de tratamento térmico investigadas neste estudo foram o tempo de residência e a taxa de resfriamento. Os tarugos termicamente tratados foram, em seguida, amostrados para caracterização microestrutural e para a execução de testes industriais de extrusão. Os resultados obtidos indicaram que existe uma significativa diferença microestrutural entre as amostras, que consistiu principalmente na variação das frações de precipitados de Mg2Si na matriz. Foi possível concluir que a produtividade na extrusão depende fortemente da fração desses precipitados.

Aug 16, 2017

By D J. D'Astoli, M D. Goodz

In 1993 a detailed review of drill sample yuuluy was rouxluard through twin and triplet drill holes using open hole, crossover suhreverse circulation (RC) and diamond drill methods. Advances in face-sampling RC methods demanded a further review of the validity and reproducibility of drill sample data. A program was undertaken to drill three RC holes using the latest technology (new face- sampling bits, dust suppressers, cyclones and compressors). Volumetric and mass studies were undertaken to review sample recoveries. Modal analyses on indicator minerals were logged to interpret the relative degree of mineralisation. Ambiguities in the results were immediately apparent and the consensus was for follow-up twin diamond holes using HQ3 coring tubes. The most mineralised RC hole was selected for the first twin diamond hole. This RC hole (MS 313) encountered one intersection of >0.47 g/t; in contrast the diamond hole (MS 342) had nine intersections at > I g/t. Results at hand show definitively that face-sampling RC drilling is not acceptable as a method of exploration for gold deposits of the Woods Point type. Furthermore it is demonstrated that RC drilling should not be used for any type of exploration of high-grade gold vein deposits related to highly fractured or porous hostrock, or areas of previous mining activity. Methods are proposed for reviewing of rates of sample recovery, distribution and cross-contamination. Comparisons also show that in limited metreage reconnaissance drill programs, diamond drilling is more similar to percussion in per metre costs, than it is credited with, and always provides more bang for the Buck.

Jan 1, 1997

By P. R. Desam, J. D. Miller, A. Datta

The flow behavior of bubble-particle aggregates in separation tanks is important for many flotation systems, particularly for wastewater treatment. These aggregates can be considered as the dispersed phase in a continuous liquid phase of water and the flow characteristics determine the efficiency of the bubble separation process. In this work, a general methodology for the computational fluid dynamics (CFD) simulation of a bubble separation tank is described. This system is analyzed by Eulerian-Lagrangian approach. The momentum transfer from the dispersed phase to the continuous phase is quantified using the Particle-Source-In Cell (PSI-Cell) method. With CFD simulations, the effectiveness of different tank design parameters are evaluated in terms of the extent of bubble separation.

Jan 1, 2000

THE activity of the principal oil fields of Rumania followed the same course as in 1939. It was marked by (1) collaboration between the various companies, particularly in exploiting oil at great depths with a view to rationalizing the exploitation and decreasing the difficulties inherent in very deep drilling; and (2) economy in the exploitation of the older pools in reducing to a minimum the cost of the extraction and working over of wells by the concentration of productive wells in groups. The pooling arrangement continued at Tintea as a measure of conservation, and exploitation of the unitized region went forward on the basis of the norms established in 1939. The same methods were applied in the fields of Liesti, Ceptura and Boldesti. The petroleum industry had some difficulty in providing the necessary material and the hands for work. Importation of material and machines from the United States was virtually stopped. Substitutes were provided from Germany but particularly useful were certain dispositions made by the local metallurgical industry. Despite the higher cost of the production of local material and machines, they were superior to the German product, the difference in quality justifying the higher price charged as the materials were found to be particularly adapted for the purposes of the petroleum industry. The cost of production was still further raised by the work that was imposed for national defense. The rise in costs per meter drilled was 50 per cent over those of 1939. According to bimonthly tables furnished by the Moniteur du Petrole Roumain, the deepest well completed in 1940 was an exploratory well, No. 201 of the Concordia company, drilled at Tintea and suspended at 3338 meters. This depth was reached toward the close of 1939 and the well was not deepened in 1940 became of large deviation from the vertical. The record for productive wells had been held by No. 429 at Tintea, drilled by Unirea to a depth of 3200 m., and in 1938 well No. 317 Cocorasti-Mislea, of the Colombia company, but these records were passed in 1940 by well No. 613 Liliesti of the Con-cordia company, which reached a depth of 3294 m. and had an initial production of 10 tons per day. In 1940, the same number of wells, II, had been drilled to a depth of over 3000 m. as in 1939. Five of these wells are at Tintea and six at Liliesti. Table I lists these very deep holes in the order of their depth. Table i.—Deep Wells Drilled in Rumania in 1940 Initial No. Produc- of Company Field Meters tion, Well Meters Tons per Day 405 Colombia......... Liliesti 3,001 10 629 Unireu............ Tintea 3,005 73 426 Unirea............ Tintea 3,050 48 410 Colombia. ........ Liljesti 3,055 30 627 Concordja (Unirea). Liliesti 3,072 75 430 627ConcordjaConcordia (Unirea). (Unjrea 3,II9 30 618 Colombia......... Liliesti 3,168 70 24 Steaua Romana. . . Tintea 3,184 18 412 24Unirea............ Tintea 3,211 23 613 Concordia......... Liliesti 3,294 10 Production in Rumania in 1940 reached 5,813,000 tons, in contrast to 6,~40,0oo tons in 1939, a decline of 427,000 tons, or 6.8 per cent. Drilling reached 241,500 m., in

Jan 1, 1941

THE activity of the principal oil fields of Rumania followed the same course as in 1939. It was marked by (1) collaboration between the various companies, particularly in exploiting oil at great depths with a view to rationalizing the exploitation and decreasing the difficulties inherent in very deep drilling; and (2) economy in the exploitation of the older pools in reducing to a minimum the cost of the extraction and working over of wells by the concentration of productive wells in groups. The pooling arrangement continued at Tintea as a measure of conservation, and exploitation of the unitized region went forward on the basis of the norms established in 1939. The same methods were applied in the fields of Liesti, Ceptura and Boldesti. The petroleum industry had some difficulty in providing the necessary material and the hands for work. Importation of material and machines from the United States was virtually stopped. Substitutes were provided from Germany but particularly useful were certain dispositions made by the local metallurgical industry. Despite the higher cost of the production of local material and machines, they were superior to the German product, the difference in quality justifying the higher price charged as the materials were found to be particularly adapted for the purposes of the petroleum industry. The cost of production was still further raised by the work that was imposed for national defense. The rise in costs per meter drilled was 50 per cent over those of 1939. According to bimonthly tables furnished by the Moniteur du Petrole Roumain, the deepest well completed in 1940 was an exploratory well, No. 201 of the Concordia company, drilled at Tintea and suspended at 3338 meters. This depth was reached toward the close of 1939 and the well was not deepened in 1940 became of large deviation from the vertical. The record for productive wells had been held by No. 429 at Tintea, drilled by Unirea to a depth of 3200 m., and in 1938 well No. 317 Cocorasti-Mislea, of the Colombia company, but these records were passed in 1940 by well No. 613 Liliesti of the Con-cordia company, which reached a depth of 3294 m. and had an initial production of 10 tons per day. In 1940, the same number of wells, II, had been drilled to a depth of over 3000 m. as in 1939. Five of these wells are at Tintea and six at Liliesti. Table I lists these very deep holes in the order of their depth. Table i.—Deep Wells Drilled in Rumania in 1940 Initial No. Produc- of Company Field Meters tion, Well Meters Tons per Day 405 Colombia......... Liliesti 3,001 10 629 Unireu............ Tintea 3,005 73 426 Unirea............ Tintea 3,050 48 410 Colombia. ........ Liljesti 3,055 30 627 Concordja (Unirea). Liliesti 3,072 75 430 627ConcordjaConcordia (Unirea). (Unjrea 3,II9 30 618 Colombia......... Liliesti 3,168 70 24 Steaua Romana. . . Tintea 3,184 18 412 24Unirea............ Tintea 3,211 23 613 Concordia......... Liliesti 3,294 10 Production in Rumania in 1940 reached 5,813,000 tons, in contrast to 6,~40,0oo tons in 1939, a decline of 427,000 tons, or 6.8 per cent. Drilling reached 241,500 m., in

Jan 1, 1941

By Edward J. Chuhta, Joseph E. Chilton, Robert J. Timko

in underground mines to measure worker exposure to various gases such as methane, carbon monoxide, and nitrogen dioxide (NO2). Even in relatively small concentrations, NO2 can produce harmful side effects in underground workers. Mines using equipment powered by diesel engines, carrying out explosive blasting operations, and performing extensive arc welding and/or cutting work will have measurable quantities of NO2 released by these processes. Workers in these areas often use gas monitors to warn of excessive gas concentrations and to help them determine when to increase ventilation air that will dilute these gases, thus minimizing exposures to this gas. Portable gas monitors, used to measure NO2 levels, must be calibrated before each use. Calibration is typically performed using a small portable pressurized cylinder containing a certified gas mixture. The certified NO2 standard mixture, usually 10 ppm NO2 concentration, is diluted with either air or nitrogen gas. To determine the stability of commercially available portable gas standards, two different cylinders containing NO2 in nominal 10-ppm concentrations were examined. One cylinder was diluted in air, the other, in nitrogen. Baseline NO2 mixtures were generated using a standard liquid NO2 permeation tube operated at a constant temperature. Final dilutions of the test gas mixtures were made with air or with nitrogen using a mass flow-controlled gas dilution system. This study showed that, when a permeation-type NO2 generator is used, the electrochemical sensors in portable NO2 monitors provide identical results for gas mixtures whether they are diluted with air or with nitrogen. Two different gas monitors, one with a two-electrode sensor and one with a three-electrode sensor, were used to measure gas concentrations in the two commercially available cylinders. One month after the cylinders were delivered, the NO2-in-nitrogen cylinder, stated to contain 10 ppm NO2, measured 8.13 ppm. The NO2-in-air cylinder, also stated to hold 10 ppm NO2, measured 6.88 ppm. Therefore, before using NO2 gas cylinders to calibrate monitors, it is recommended that their concentrations be verified either by manufacturer recertification or by comparing the stated cylinder gas concentrations to a laboratory-based permeation tube-generated standard.

Dec 1, 2005

By Andrew Mayer

Early in 1942 National Lead Co. was requested by the War Production Board to construct and operate a plant for the Government to produce magnesium by the ferrosilicon process which had been developed by Dr. E. M. Pidgeon in the laboratories of the Canadian National Research Council. A contract with the Defense PlantCorporation was concluded in May 1942 and Magnesium Reduction Co., a wholly owned subsidiary of National Lead Co., was formed to carry out this project. The capacity of the plant was rated at I0,000,000 lb. of magnesium per year, equivalent to an average production of about 14 tons per day. The Process The process, in brief, is as follows: The raw materials are dolomite and ferro-silicon, 75 per cent grade. The dolomite is calcined, the calcine and ferrosilicon are ground and mixed and the mixture is briquetted. The briquets are charged into tubular retorts of chrome-nickel steel set horizontally in a furnace with the open ends projecting outside the front wall. The retorts are then closed and evacuated. Magnesium is liberated according to then reaction 2(MgOl CaO) + Si = 2Mg + zCaO, Si% It is distilled from the charge and con- densed on a removable sleeve in the throat of the retort. Sodium and potassium, if present, are also liberated, distilled and condensed on a "sodium condenser" in the end of the retort. At the expiration of the distillation period the retorts are discharged and the cycle of operations is repeated. For the rated daily capacity of 14 tons of magnesium there are required approximately 170 tons of dolomite, equivalent to about 85 tons of calcine, and 16.5 tons of ferrosilicon. The retort residue, a bulky powder which at present is waste, amounts to about 87 tons. Choosing the Site The investigation to select the location of the plant was conducted by the Research Laboratories of National Lead Co. This work included geologic and economic surveys of a number of districts, examination of dolomite samples by chemical, spectrographic and petrographic methods and large-scale tests of dolomite from several of the more promising localities. in the last-named tests 2-ton samples were put through the ferrosilicon process in the pilot plant of the Canadian National Research Council, under the guidance of Dr. Pidgeon. The conclusions drawn from the investigation, in regard to the quality of dolomite to be used in the ferrosilicon process, were: First, the dolomite should contain not less than 21 per cent MgO and not more than 2 per cent acid-insoluble material. Second, the dolomite should

Jan 1, 1944

By J. O. Brittain, E. P. Lautenschlager, F. Felberbauer

This investigation was undertaken to evaluate the effect of a dispersed phase in a iron upon the strain hardening and the stress dependency of dislocation velocity as inferred from the strain-rate sensitivitv. Experiments were made in a-iron specimens with controlled amounts of carbon and/or A12O3. They were tested at various temperatures between 195' and 373 'K under a variety of conditions oj-concentration, strain rate, and quench aging. The resulting yield strength, flow strength, and strain hardening increased with addition of Al2O3. The parameter m, measured from changes in strain rate, was xsed to describe the stress dependency of the dislocation velocity. m was found to increase with additions of A12O3, increasing carbon in solution, and with increasing temperature. When applied to a recent model for yielding based upon dislocation multiplication and velocity characteristics, the values of m alone did not successfully predict yielding for the materials of this investigalion, but had to be adjusted with a consideration of the number of unlocked dislocations nucleated heterogeneously at discontinuities or inclusions. The change of yield strength with Al2O3 Interpar-ticle spacing appeared to obey a theory of Orowan. EVER since the concept of dislocations has been introduced to explain plastic deformation in crystalline materials, the origin of dislocations and the source of the number of dislocations required to account for plastic deformation have been persistent questions. Ruling out the possibility of homogeneous nucleation,' Gilman2 drew attention to the various cases of heterogeneous nucleation as the source of dislocations, whereas Frank and Read3 introduced the Frank-Read source. However, Gil-man found that the Frank-Read sources did not play a dominant role in the deformation of LiF crystals, but that small precipitates are often, if not always, associated with the nucleation of dislocations. In LiF crystals, however, most of the dislocations arose through the multiplication of moving dislocations in a mechanism described by Koehler4 and Orowan,5 Thus, relatively few precipitates could account for a large number of dislocations. A similar observation of dislocation nucleation at inclusions of precipitates was made by Stein and LOW' on Si-Fe crystals. Their crystals contained

Jan 1, 1964

By Trevor Yeomans

"NVI Mining’s Myra Falls Operation is a forty year old underground mining operation feeding a 4000 mtpd concentrator.The current Mill, built in 1985, was designed to process a large massive sulphide ore-body. This ore-body, known as the “HW”, contains about 50% pyrite. Value minerals are chalcopyrite, and sphalerite, with precious metals occurring in all mineral types.By 1997, mining of a new ore-body, known as “Battle-Gap” commenced. Mineralogically complex, the new orebody contains about 15% pyrite, copper minerals including primary chalcopyrite, secondary bornite, chalcocite and tennantite, combined with increased galena and sphalerite.Flotation performance generally decreased with increasing amounts of Battle-Gap ore types, with both copper concentrate quality (increased lead and zinc content) and copper recoveries being affected.Following significant metallurgical testwork, a new fully sequential copper-lead-zinc flotation flowsheet and reagent scheme was developed.This sequential flowsheet was progressively installed and commissioned during 2006.Copper concentrate lead and zinc smelter penalty contents have been reduced by some 40%, whilst increasing copper recovery by 10%.INTRODUCTIONNVI Mining operates the Myra Falls Operation near Campbell River on Vancouver Island, BC. The complex has been in operation since 1966 with mining being predominantly underground. One unique feature of Myra Falls is that the mine operates within a BC Provincial Park.In 1985, a new large massive sulphide ore-body (HW) had been defined, and metallurgically tested. A new concentrator was built based upon this massive pyrite, chalcopyrite, and sphalerite mineralization producing copper and zinc concentrates by conventional flotation methods."

Jan 1, 2008

By Tianrui Xu, Chaohong Liu, Bangqing Ding

The authors were responsible for a series of large scale multiple chamber charge blasts conducted in the granite mountain area for making construction space on the southeast sea coast in China during 1993-1996. This paper describes the blast design and damage control of one mountain blast 320m in length and 280m in width in the vicinity of two wharfs and a dam. In order to obtain better rock fragmentation and muckpile, the explosive charge should be well-distributed in the mountain. The charge pattern, therefore, was designed with mainly 5 rows of tunnel charge in regular terrain in combination with a chamber charge in irregular topography area and the maximum burden was limited to be less than 38m. In order to protect the dam and wharfs the firing sequence was carefully arranged in 29 intervals and the distance between different charges of the same delay to the dam or wharf was taken into account as an additional delay interval based on the difference of p-wave propagating times. The maximum charge fired in an interval was also limited to less than 34t explosives through dividing the larger charge by a stemming deck.

Jan 1, 1998

Geotechnical conditions in the Lochiel Deposit are somewhat unusual, and thus geotechnical and hydrological investigations have assumed a high priority. The cost of mining the deposit has been shown to be very sensitive to geotechnical design parameters, and it is now seen to be of paramount importance to establish a high level of confidence in the design parameters used for mining cost estimation. Geotechnical investigations in the Lochiel Deposit reached a crossroads in 1985, when there appeared to be several quite different and equally attractive routes to follow to establish a satisfactory level of confidence in geotechnical mine design parameters. Three main options were identified, referred to as the No Further Work Route, the Drill and Trench Route, and the Trial Pit Route. The No Further Work Route was ruled out as being technically unsound and as satisfying none of the Electricity Trust of South Australia's (ETSA's) or the State Government's requirements. The planning process for further geotechnical investigation involved: clearly identifying the current status of work and significant geotechnical and geological factors planning and costing the alternative schemes for improving knowledge assessing the increase in knowledge to be gained from the alternative schemes . choosing the preferred scheme This process resulted in ETSA's

Jan 1, 1986

By S. Shapiro, G. Krauss

The strutural and cr~stallo~aphic features of the plates of austenite produced by the martensite to aus-tenite or reverse martensitic tramformation have been determined in an Fe-33 wt pct Ni alloy. Micro-focus X-ray techniques and single-surface trace analysis 072 bulk samples yielded two distinct habit planes, (0.174, 0.309, 0.~35)~ and (0.375, 0.545, 0.749jM. The former plane uas the one predorninantly observed and its existence was verified by transn~ission electron microscopy. The orientation relation-ship between the reversed austenite and the parent martensite was approximately the same as the Nishiyamna and other relationships reported for the direct tramformation. Replica and thin-joil obser-vations show that both high densities of tangled dis-locations and occasional twins constitute the fine structure of the reversed austenite. Application of the phenomenological theory to a variant of the predominant habit plane defines an irrational plane and direction for the second shear in accordance with the comnplexity of the fine structure. The shear accompanying the reverse martensitic transformation is at least 0.51, the maximnum value of- the tangent oJ the tilt angle measured on surface replicas. A mechanism relating the fine transformation twins in martensite to the nucleation of reversed austenite of the predominant habit is proposed. The reversal of Fe-Ni martensite takes place both at the edges of martensite plates and in a piecewise fashion within them.' The shear-type nature of the reverse transformation is verified by the surface relief which accompanies both edge-type reversal2 and the fragmentation of plates of martensite' as a result of rapid heating above the A, (austenite start temperature). The orientation relationship between the edge-type reversal product and the parent martensite, as determined by transmission electron microscopy, is reported to be within 4 deg of either the Kurdyumov-Sachs or Nishiyama relationships,' but there is no work at present in the literature relating to the crystallography of the platelike reversed austenite. The fine structure of reversed austenite after heating to 50°C above the Af is reported4 to be composed primarily of tangled and jogged dislocations in concentrations up to 10" per sq cm. A replica investigation of partially reversed Fe-Ni martensites5 corroborates the increase in dislocation density following reversal and presents indications of other possible modes of fine structure. This paper reports on an investigation performed to examine in detail the morphology and crystallography of the plates of reversed austenite and the shear which accompanies their formation in a matrix of Fe-Ni martensite. EXPERIMENTAL PROCEDURE Discs of a high-purity Fe-32.9 wt pct Ni single crystal served as the starting material. The single crystal had been produced in the course of an earlier investigation6 and the carbon content was determined at the time to be 0.006 wt pct. The M,, and the A,, were respectively -120" and 300°C. Partial transformation to martensite was performed at -125°C and reversal of some of the martensite was accomplished by heating in the temperature range 340" to 355°C. Most samples were heated to the reversal temperature by immersion' in a salt bath for 2 min. For surface-relief studies some polished and etched Samples were heated in a tube furnace for ten min in a hydrogen atmosphere maintained over the samples throughout the heating and cooling cycles. Samples were prepared for metallographic examination by electropolishing and etching with an HC1-HNOs-H20 et~hant.~ On one of the surface-relief samples two sets of fiducial scratches were placed on the etched sample by drawing it over a slurry of 0.06 p alumina on a "microclothJ'. The orientations of individual plates of martensite were determined by X-ray analysis. A Rigaku-Denki microbeam X-ray generator in conjunction with a Micro-Laue camera with facility for precision location of the sample in front of the beam was employed for this purpose. The collimator size was 30 p and the specimen to film distance was 5 mm. The Laue photograms were enlarged to an equivalent 3-cm specimen to film distance for analysis. The orientation of each of the plates of martensite was compared to that of the parent austenite and the relationship be -tween the two phases was, in all cases, within a few degrees of those predicted for the direct transformation. The orientation relationship between one of the larger plates of reversed austenite and its parent martensite was determined in a similar manner. The habit plane of the islands of reversed austenite in the X-rayed plates of martensite was determined by a single-surface trace analysis. Each reversal island had with the parent phase one comparatively straight boundary which was presumed to represent the habit plane trace. The pole locus technique7 was applied to traces from six different plates of martensite to determine the indices of the habit plane. A 40-cm stereographic net was employed for this analysis The morphology and fine structure of the reversed austenite were studied by electron microscopy of pre-shadowed direct carbon replicas,5 and the macroscopic shear was evaluated by a two-stage replica technique similar to that employed in electron fractog-

Jan 1, 1968

By Dennis L. Paisley, Thomas P. Turner

Laser slapper detonators are the next generation detonator under development at the Detonations Systems Group at Los Alamos National Laboratory and function very similarly to an electrical slapper. A fiber optic transmits a laser pulse to ablate a thin metal film. This film, or flyer as it is commonly called, is launched through a short barrel to km/s speeds. The flyer shock loads or slaps a high density pressing of secondary explosive, setting off a detonation therein. Laser slapper detonators afford a number of safety advantages over other conventional detonators. Most important they require very high peak laser powers to operate, orders of magnitude larger than possible sources of natural or man-made accidental stimulus. Because light is transported over fiber optics, laser slappers avoid many of the electrical hazards associated with detonators. Use of insensitive, secondary explosives makes these detonators safer to handle, manufacture, transport, and deploy.

Jan 1, 1994

By Karl E. Burgher

Since World War II, the need for the use of explosives with testing, construction, demolition, mining and quarrying near urban areas has increased dramatically. Once remote, testing areas have been encroached upon by commercial and residential areas. Evidence has been found that overpressure levels near these areas can be estimated using meteorological conditions. This paper reviews a study where 205 test shots were fired, meteorological conditions recorded, and over-pressure levels estimated using multiple regression techniques.

Jan 1, 1988

By Charles C. Dahl, Gordon C. Presley, Andrew E. Nevin, Bruce A. Kennedy

How does SME-AIME cope with profound changes in technology, markets - and most importantly - in employment patterns facing its membership today? This is the question that prompted the Society's Board of Directors to appoint a Long-Range Planning Commission (LRPC) (see ME, Feb. 1984, pp. 118 and 128). This is also the question addressed most particularly by the LRPC's Scope Committee. The Committee started its deliberations by asking such basic questions as "Who are we?" and "What is our business?" The Scope Committee then reviewed the findings and recommendations of other more specialized committees to develop and integrate their concepts of the Society's business for the next 10 years. The policy-making suggestions of the LRPC were reviewed and acted upon by the Board of Directors at its open meeting in Los Angeles on Feb. 26, 1984. At the Oct. 23-26, 1984 SME Fall Meeting in Denver, the Board will again review LRPC recommendations. In answer to the question "Who are we?" the Scope Committee proposed description, which was accepted by vote of the board of directors: . . A technical and professional organization that consists of individual members, namely those mining engineers, metallurgists, geologists, earth scientists, economists, managers, educators, and other professionals concerned with all facets of exploration, production, distribution, and using of mineral commodities. "These mineral commodities include all metals; industrial minerals, including construction materials and fertilizers; coal, oil shales, tar sands, and other mined fuels. Among the earth's mineral resources, only wellpumped oil and gas lie outside the Society's specific purview. "Traditionally, SME members work in the fields of engineering, technology, exploration and discovery, development, construction, mining, quarrying, beneficiation and processing, handling and transport, equipment manufacturing, sales and marketing, data processing, safety, land reclamation, environmental protection, taxation, administration, and management of these elements. "Members practice their professions in industry, in universities and research institutions, and in government. They may be operators, manufacturers, sales persons, contractors, consultants, analysts, researchers, educators, advisors, regulators, or members of supporting staffs. "The members of the Society are leaders in dedication to their crafts, in innovation, and in the pursuit of excellence. Among their numbers they count the most distinguished of engineers, applied scientists, and managers. "The Society is based in the United States, is active on a worldwide basis, and is open to nationals of any country. Certain qualifications must be met for attaining and maintaining membership." Purpose of the Society As to the question "What is our business?" the Scope Committee restated our purpose in light of current practice and the constitution of AIME and the bylaws of AIME and SME. The Board of Directors accepted the following proposed purpose of SME: "To further the professional development and well-being of its members by publishing and distributing technical writings, news, and information; by sponsoring meetings of members; by providing forums for discussions and for continuing education; and by fostering communication on the subjects within its purview. "The Society assists educa-

Jan 4, 1984

By Nikolas K. Sokol

Underground construction often requires working within a very congested urban environment, including excavating shafts adjacent to highly sensitive and multistoried structures, sometimes even within such structures. Shafts adjacent to heavily loaded column footings are often required due to space constraints. Invariably, footing surcharges must be considered during the design of shaft rock reinforcement. Rockwedge stability evaluation reveals that column surcharges can greatly impact the ability to meet the desired factor of safety. Design methodologies and examples to deal with these special circumstances are presented.

Jan 1, 2008