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By Patrick Linehan

Vibration and air blast noise from blasting were evaluated during a research program which was sponsored by the U. S. Bureau of Mines. Blast variables were studied using small scale model (SCM) tests to evaluate specific variables as well as interactive effects, followed by experiments with production blasts at the surface coal mines. Experimental data showed that the primary variables affecting the ground vibration amplitude are the charge weight per delay and the length of the delay interval. Blast variables having a significant effect on the overpressure amplitude include the charge weight per delay, the length of the delay, burden and spacing, stemming amount and type, direction of initiation, charge depth and amount of detonating cord and cover.

Jan 1, 1980

COLUMBIA SECTION J. C. HAAS, Chairman W. J. HALL,. Vice-chairman LYNDON K. ARMSTRONG, Secretary-Treasurer, 720 Peyton Bldg., Spokane, Wash. W. H. LINNEY J. F. MCCARTHY At a meeting of the members of Columbia Section, which was held in the Davenport hotel, Spokane, Wash., Jan. 31, 1919, at noon, there were present' about twenty members and guests. The chairman being absent, Mr. Frederick Keffer presided. The Secretary announced the personnel of the executive committee of the section, which is: J. C. Hass, Spokane, Chairman; W. J. Hall, Wallace, Ida., Vice-chairman; S. S. Fowler, Riondel, B. C., Past Chairman; L. K. Armstrong, Spokane, Secretary-Treasurer; R. M. Betts, Cornucopia, Oregon. It was stated that the geological survey and report on Stevens Co., Wash., has been completed and will be printed soon. The geologic survey of Colville Indian reservation, by J. T. Pardee, U. S. G. S., has been published as Bulletin No. 677 and is available for distribution, The Miner's Almanac, Miners Circular No. 24, U. S. Bureau of Mines. is also available upon request. There was considerable discussion on the program for meetings during the year. It was informally agreed that, if agreeable to Coeur d' Alene members, that one meeting should be held in that district, preferably at the time of the annual visit of Institute officials. It was also proposed to hold at least one open-air meeting in Spokane with suitable program. The activities of other sections were noted with favorable comment. In this connection there was much general discussion on the subject of closer relations between the national engineering societies. It was agreed that cooperation was desirable and imperative if the greatest measure of value be realized from the profession. It was not the sense of the members, however, that complete amalgamation is desirable. This expression of local sentiment is to be presented to the Institute

Jan 3, 1919

By Chen Jianhua, Shen Zhenchang, Zhang Ming, Chen Feifei

"With flotation cells scale-up, the performance of flotation cells is increasingly variated for short-coming and dead zones existing. The residence time distribution which shows the movement of tracers can assess the unexpected flows such as short circuit and dead zone in a flotation cell. In this paper, the residence time distribution of pilot flotation cell is investigated with CFD simulation. Based on the theoretical model, the short-coming probability and dead zone probability are quantitative. The ideal average residence time is similar with the actual average residence time. The mixing effect of the flotation cell approaches the ideal continuous stirred tank reactor. The operating parameters such as speed and feed velocity have complicated influence on residence time distribution. The research would be helpful to understanding flow in flotation cell and improving performances of flotation cell.INTRODUCTIONFroth flotation is a method which purifies minerals according to difference of physical and chemical surface characters of different mineral particles (Shen, Z., Chen J, 2012). Flotation cell is a key equipment for froth flotation method. The flotation cell performances have great influences on flotation index.It is difficult to evaluate flotation cell how to improve flotation procedure to complexity.The main flotation cell performances are aeration volume, air dispersion, solid suspension and residence time distribution, etc (Shen, Z., Lu, S., 2008). Residence time distribution is an important fluid hydrodynamics which could reveal the flow of pulp, mixing of particles and air bubbles. In the flotation cell, the ideal average residence time of pulp could obtain easily. But the fluid differential units would be different flow paths. The residence time of the fluid differential units is variation and would be longer or less than the average residence time. The residence time distribution would reveal the mixing effect and predict the not ideal flow in the flotation cell such as shorting cutting, dead zone, etc. As we know, the shorting cutting and dead zone would be decreased the real flotation time and it is disadvantage to better flotation effect, especially for large flotation cell. It is impossible to eliminate the not ideal flow totally. It is very important to reveal and decrease the shorting cutting and dead zone probability in the flotation cell."

Jan 1, 2018

By M. C. Bleiweiss

Various light sources were evaluated for use in a fiber optic lighting system for mining machines. It was determined that a metal halide arc lamp was best because of its resistance to damage from shock and vibration and the high luminance of the arc. Measurements were made of the percent transmission of the ½ inch thick glass window and the fiber bundles, the total lumen output of the diffuser assembly with a known input and of the average surface luminance of the diffuser assembly. These data were then used to calculate the theoretical output of the system given an estimated input from the source. A prototype 55 watt, single-ended metal halide source was then developed. In order to provide greater efficacy and higher throughput through the fiber optic cables, a variation of the lamp with thallium iodide added to the fill was developed. The lamp was modified and a ballast was developed to allow it to hot restrike.

Jan 1, 1986

By H. A. Doerner

PROPOSALS to use hydrocarbon or natural gases for the reduction of zinc from oxide materials may be traced back through Patent Office files to the early years of the present century. Natural gas at rates cheap enough to compete with solid fuels has been available at or near one major zinc district for more than a decade. That the seemingly meritorious and economically interesting applications of these proposals have not devel-oped into workable processes for direct production of zinc by natural gas cannot be completely ascribed to the proverbial conservatism of the zinc industry. It is possible to produce spelter commercially in normal times from zinc oxide and carbonaceous reducing agents without having a very precise understanding of the chemistry of the process. The reduc-tion by hydrocarbons is not, however, in this class, and the technical complexity of this reduction metallurgy and chemistry prohibits solution of the inherent difficulties by the "hit and miss" methods that are some-times thought to be practical. In a thermodynamic study of the chemistry of zinc smelting, Maier1 made a preliminary study of the chemistry of the use of methane for reducing zinc oxide by thermodynamic means, pointing out that the following reactions, the limits of which could be theoretically predicted, were important: ZnO + CH4 = Zn(gas) + CO + 2H2 [1] CH4 = C -I- 2H2 [2] ZnO + CO = Zn(gas) + CO2 [3] ZnO + H2 = Zn(gas) + H2O [4] Other possible reactions, not discussed in the reference quoted, are: CO2 + CH4 = 2CO + 2H2 [5] H2O + CH4 = CO + 3H2 [6]

Jan 1, 1933

By James E. Cairelli

The NASA Lewis Research Center, under U.S. Bureau of Mines program direction, performed an assessment of alternative mobile power sources for mining applications. A wide variety of heat engines and energy systems was initially examined to ascertain which could be considered as potential alternatives to presently used power systems. The present mobile power systems are electrical trailing cable, electrical battery, and diesel - with diesel being largely limited in the United States to noncoal mines. Each candidate power source was evaluated in terms, of the following requirements: (1) Ability to achieve the duty cycle (2) Ability to meet Government regulations (MSHA certification) (3) Availability (production readiness) (4) Market availability (5) Packaging capability An initial screening reduced the list of candidates to the following: (1) Diesel (2) Stirling (3) Gas turbine (4) Rankine (steam) (5) Advanced electric (batteries) (6) Mechanical energy storage (flywheel) (7) Use of hydrogen evolved from metal hydrides This list of candidates was divided into two classes of alternative power sources for mining applications - heat engines and energy storage systems. A summary of each class follows.

Jan 1, 1981

By John Birkinbine

FOR two years past the Warwick Furnace, at Pottstown, Pa., has attracted attention by the remarkable work done in it, and a statement giving details of its operation and the unexpectedly short blast of 1880 will be acceptable to every member who studies blast-furnace practice. There are so many interesting features in con¬nection with this blast, and so much to be learned from investigating it, that the results of a thorough examination are offered to the Institute sans theories. In collecting the information, the courtesy of the various officers of the Warwick Iron Company was of material advantage, every facility for investigation being extended and an inspection of records being kindly permitted. In the following description these authoritative data are given in full where practicable, without making the paper too prolix, and the

Jan 1, 1881

By John Birkinbine

For two pears past the Warwick Furnace, at Pottstown, Pa., has attracted attention by the remarkable work done in it, and a statement giving details of its operation and the unexpectedly short biast of 1880 will be acceptable to every member who studies blastfurnace practice. There are so many interesting features in connection with this blast, and so touch to be learned from investigating it, that the results of ' thorough examination are offered to the Institute sans theories. In collecting the information, the courtesy of the various officers of the Warwick Iron Company was of material advantage, every facility for investigation being extended and an inspection of records being kindly permitted. In the following description these authoritative data are given in full where practicable, without making the paper too prolix, and the

Jan 1, 1881

By Uday B. Pal

In the electrochemical vapor deposition (EVD) process, gaseous cation precursors are passed over one side of a porous substrate, and oxygen is passed on the other side of the substrate. The gases diffuse and react within the porous substrate, and the pores get filled with the desired solid oxide. Subsequent solid state electrochemical transport through the solid oxide in the pores continues the reaction, and the film grows over the porous substrate. The EVD process has been used to deposit lanthanum chromite interconnection films and yttria stabilized zirconia electrolyte films over porous air electrodes. The EVD growth of these solid oxide films is found to be parabolic in nature, which indicates that the solid state transport (diffusion) of ions through the film controls the growth. This solid state transport can be analyzed using Wagner's treatment of the electrochemical transport. Conductivity measurements and the information on the defect structure of the oxide can be combined with the EVD growth rate measurements to calculate the solid state transport properties (transport numbers and partial conductivities) of the rate-controlling minority species in the oxide. Using this approach, the EVD growth of other electronic, mixed conducting and ionic solid oxide films can also be analyzed.

Jan 1, 1992

By John M. Pitt

A rapid in situ stress measurement technique was developed for exposed underground surfaces. The method applies radial stress in small diameter (38mm) boreholes, initiating fracture propagation which is monitored by measuring ultrasonic pulse velocity. Theoretical relations for stress concentrations near boreholes provide independent expressions for unknown principal field stresses at incipient fracture; fracture orientation defines principal stress orientation. Accuracy and precision were evaluated using blocks of brittle material subjected to known stresses. Results were comparable to those obtained by other in situ stress measurement techniques.

Jan 1, 1984

By J. H. East, R. S. Sanford, W. M. Traver, W. S. Wright

"INTRODUCTION This report describes the results obtained from a diamond-drill exploration project performed by the Bureau of Mines on the nickel deposits of the Yakobi Island, Alaska. The Federal Geological Survey 6/ completed a detailed geologic study and mapped the area during the summer of 1940, and a Bureau of Mines examining engineer 7/ made a preliminary examination of the deposits in June 1941, at which time core drilling was suggested as the logical means of determining the extent and grade of the deposits. Equipment and supplies were unloaded on the beach at Yakobi Island on October 21, 1941. The drills were moved to Bohemia Basin, where actual drilling operations wore begun under the direction of a Bureau of Mines engineer 8/ on November 7, 1941. Two core-drill holes were completed on December 7, 1941. Upon the request of the drilling contractor, operations were recessed owing to severe winter conditions. Work on the project was resumed April 27, 1942, under the direction of another Bureau of Mines engineer 9/ and was completed August 15, 1942. During the 1942 season, 13 core-drill holes were completed, and 10 surface pits and a tunnel were sampled. A total of 5, 191 feet of core-drill hole was drilled in 15 holes during the entire project. The results of drilling and sampling form the basis of this report."

Jan 1, 1948

By Walter Craft, John L. Lamont

Adequate hardenability has long been recognized as one of the first requirements for producing desired mechanical properties in a heat-treated steel. Since the introduction of the Jominy end-quench test' and the development of correlative information to expand its use, industry has had an effective measure of hardenability. Prediction and control of the hardenability have been made possible by Grossmann's principle2 for calculating hardenability from chemical composition; and Field's conversiona from depth of half-martensite hardening to Rockwell C hardness has made the relation more quantitative. These developments have facilitated the design of new steels and the control of standard grades to the extent that it has been possible to establish tentative hardenability bands for some of the more commonly used alloy steels.4 As the depth of hardening of the Jominy test specimen is usually measured by Rockwell C hardness, it was considered that it should be possible to predict the hardness by a more direct calculation. It has been found that this can be accomplished by the addition of Rockwell C units proportional to the carbon and alloy content, grain size, and position in the Jominy test specimen. The calculation has been found to be fairly accurate, and because of its additive character is relatively simple to use. In principle the method of calculation is somewhat similar to the expressions developed by Herty, McBride, and Hollen-back,5 Burns, Moore, and Archer,= and Burns and Riege1.l The calculation is started from a base that includes the effects of carbon content and position in the Jominy test speimen. Rockwell C units are added to the base in proportion to the alloy content and grain size. This sum represents the Rockwell C hardness up to the level at which a disproportionate increase of hardness is caused by the formation of martensite, and above this level an increment for martensite hardening is added. The effects of alloys are directly proportional to the amounts present and are independent of each other, the carbon content, and the position in the specimen. Furthermore, the factors for determining the martensite increment are dependcnt only on carbon content and are independent of cooling rate and alloy content. It is this absence of interrelation between the different factors that makes it possible to calculate the hardness and makes the method of calculation consistent with the principle that the character of the hardening reaction is governed primarily by carbon and that alloys exert their effect chiefly through control of the critical cooling rate. The principle of the calculation, and the effects of alloys on the critical cooling rate,

Jan 1, 1947

By John L. Lamont, Walter Craft

Adequate hardenability has long been recognized as one of the first requirements for producing desired mechanical properties in a heat-treated steel. Since the introduction of the Jominy end-quench test' and the development of correlative information to expand its use, industry has had an effective measure of hardenability. Prediction and control of the hardenability have been made possible by Grossmann's principle2 for calculating hardenability from chemical composition; and Field's conversiona from depth of half-martensite hardening to Rockwell C hardness has made the relation more quantitative. These developments have facilitated the design of new steels and the control of standard grades to the extent that it has been possible to establish tentative hardenability bands for some of the more commonly used alloy steels.4 As the depth of hardening of the Jominy test specimen is usually measured by Rockwell C hardness, it was considered that it should be possible to predict the hardness by a more direct calculation. It has been found that this can be accomplished by the addition of Rockwell C units proportional to the carbon and alloy content, grain size, and position in the Jominy test specimen. The calculation has been found to be fairly accurate, and because of its additive character is relatively simple to use. In principle the method of calculation is somewhat similar to the expressions developed by Herty, McBride, and Hollen-back,5 Burns, Moore, and Archer,= and Burns and Riege1.l The calculation is started from a base that includes the effects of carbon content and position in the Jominy test speimen. Rockwell C units are added to the base in proportion to the alloy content and grain size. This sum represents the Rockwell C hardness up to the level at which a disproportionate increase of hardness is caused by the formation of martensite, and above this level an increment for martensite hardening is added. The effects of alloys are directly proportional to the amounts present and are independent of each other, the carbon content, and the position in the specimen. Furthermore, the factors for determining the martensite increment are dependcnt only on carbon content and are independent of cooling rate and alloy content. It is this absence of interrelation between the different factors that makes it possible to calculate the hardness and makes the method of calculation consistent with the principle that the character of the hardening reaction is governed primarily by carbon and that alloys exert their effect chiefly through control of the critical cooling rate. The principle of the calculation, and the effects of alloys on the critical cooling rate,

Jan 1, 1947

By Shiou-Chuan Sun

THE fact that coals of different ranks and even of the same rank differ greatly in their amenability to iroth flotation is well known. In recognition of the need for an explanation of this phenomenon, two hypotheses have been suggested. Wilkinsl reported that the floatability of coals increased with an increase of the carbon content or rank. This postulate is handicapped by the fact that bituminous coals that possess moderate carbon contents are actually more floatable than anthracite coals that have high carbon contents, as shown in columns 6 and 9 of Table I. Taggart and his associates' implied that the difference of floatability between bituminous and anthracite coal was caused by the variation of carbon-hydrogen ratio. This is not applicable to the relative floatability of other coals and carbons. For example, column 11 of Table I shows that the carbon-hydrogen ratios of low-floating lignitic coal and non-floating animal charcoal are not only smaller than the moderate-floating anthracite coal, but are also similar to the high-floating bituminous coal. Furthermore, according to this hypothesis, high temperature coke-A (464), Ceylon graphite (1238), and lamp-black (357), all possessing extremely high carbon-hydrogen ratios, should be less floatable than other substances having much lower carbon-hydrogen ratios such as high volatile-B bituminous coal (11.9 to 22), anthracite coal (35.7 to 60.5), lignitic coal (15.6 to 33.6), and charcoal (13 to 26.2). However the former group is actually more floatable than the latter group. In this paper, a surface components hypothesis is Proposed to explain the different floatabilities of coals, carbons, and hydrocarbon minerals. The validity of the hypothesis is experimentally supported by the actual floatability, natural floatability, wettability, and adsorbability for neutral oils of coals, carbons, and hydrocarbon minerals tested. The combustible recovery of the flotation results, as used in this paper. was calculated from Eq. 1: P (100-Ep) 100 RWCP Rc= [1] F (100-E,) C, where R, is the percent combustible recovery; F and P are, respectively, the weight of feed and the weight of concentrate or product; E, and Ep are, respectively, the total percent of ash plus moisture in feed and in concentrate; Ru. is the percent weight recovery: and C, and C, are, respectively, the percent of combustible in feed and in concentrate. Except for ash and moisture content, all chemical components of a coal are assumed combustible. The experimental work included studies on flotation, ultimate and proximate analyses, contact angle tests, extractions of bitumen-A with benzene, adsorptions for liquid hydrocarbons, and wetting tests. Most of the flotation experiments were performed in a laboratory Fagergren machine; others were tested in a small Denver machine. The solid feed for the former was 300 g and for the latter was 30 g. The solid materials used for flotation were crushed to —48 mesh. After the mineral pulp in the flotation cell was agitated for 6 min and the pH was adjusted to 7.5 & 0.2 with sodium hydroxide or hydrochloric acid, a petroleum light oil having a viscosity of 5.73 centipoises at 77 °F was added and conditioned for 2 min. Finally, pine oil was introduced and the froth was collected for exactly 3 min. The weight ratio of petroleum light oil to pine oil was kept constant at 1.5 to 1. Tap water was used for all flotation tests. Contact angles were measured with a captive bubble machine. For each coal sample, three specimens were mounted in transoptic mounts and polished with levigated alumina, first on a sheet glass, then on a cloth-covered metal polishing wheel. The polished specimen was first washed with distilled water and wiped thoroughly on a cleaned linen pad, then transferred into the pyrex cell of the captive bubble machine and conditioned for 6 min., and finally measured for contact angles at three or more points. Except where otherwise stated, the induction time for each measurement was 1 min. The contact angle representing each material was obtained by averaging the measurements of three specimens. The linen pad was first washed with warm distilled water, then boiled 30 min in a 2N sodium hydroxide solution, and finally washed with distilled water until no trace of sodium hydroxide could be detected in the decanted solution. The cleaned linen pad was stored under distilled water. Immediately before using, the pad was rewashed and transferred into a clean pyrex petri dish partly filled with distilled water. The glassware and rubber gloves used were cleaned by soaking in sulphuric acid-potassium dichromate cleaning solution, followed by rinsing with distilled water. The polished specimens were handled only by glass forceps. The ultimate and proximate analyses were made in accordance with the ASTM standard procedures for coal and coke. The extractable bitumen-A was determined by weighing 1 g of —100 mesh sample and placing it in a desiccated and weighed ASTM aluminum-extraction thimble. The thimble was placed in condenser hooks and inserted into an extraction flask containing 100 cu cm of benzene. The flask was heated and the benzene vapor was condensed by water coils. At the end of 24 hr of percolation, the thimble was removed, desiccated, and weighed. Loss in weight of sample was taken as bitumen-A and calculated to dry and ash-free basis.

Jan 1, 1955

By C. Langer

Although the existence of precious metals, particularly those of the platinum group, in the nickel ores in the Sudbury district has been known for a good many years- almost as long as the ore deposits themselves- the Mond Nickel Company were the first to effect their recovery on a commercial scale. The precious metals values of the different Sudbury ores vary considerably, and are generally higher in the copper-rich ores. These values are so very small that a direct determination in the ores gives quite unreliable results. This is not surprising if one considers that some of the ores contain on1y one unit of total precious metals in about two million units of ore, and that this one unit will consist of seven different metals, each with a different chemical behaviour. It is only after the ores have been smelted to a Bessemer matte containing about 80 per cent combined copper and nickel that the precious metals content can be determined with some degree of certainty. From the figures thus obtained, the precious metals content of the ores can be calculated, provided the tonnage of ore used to produce one ton of matte is known. The recovery of these minute quantities of precious metals out of ?such a large amount of gangue and sulphides of iron, copper, and nickel seems at first glance a commercial and technical impossibility. Nevertheless, science has found a way to conquer all the difficulties, and quite substantial quantities of the precious metals contained in the Sudbury nickel-copper ores have been regu1arly recovered for many years by the Mond Nickel Company.

Jan 1, 1927

By P. T. Velu

Light weight aluminum alloys are the major construction materials for a number of structures in automobile and aerospace industries. Higher cost of production is the key impediment which restricts the usage of these alloys. A new electrochemical process route for the low cost production of aluminum alloys is being investigated, in which alloying elements are obtained from the dissolved compound. In the present investigation, solubility of lithium compound has been determined by measuring the EMF, when it is dissolved in the electrolyte. The solubility of Li2CO3 increased with temperature from 2.95 wt pct at 1063 K to 7.57 wt pct at 1093 K. Activities of the compound in the electrolyte were deduced using Temkin's ideal solution approach.

Jan 1, 1995

By Raymond Mancha

TO determine the optimum inside dimension of an airshaft, it is necessary to strike the proper balance between the cost of power for air friction and turbulence losses within the airshaft, on the one hand, and the cost of sinking the airshaft, on the other. An airshaft larger than necessary is extravagant because the increased amortization rate exceeds the reduction in power cost. Conversely, an airshaft smaller than is needed wastes more power than can be justified by the corresponding reduction in amortization rate. The airshaft power is a function of the air volume Q cu. ft. per min. and the air- pressure drop p in. water gauge across the airshaft The airshaft pressure drop is calculated by the formula: [ ] wherein R is the air-friction coefficient for the portion of the airshaft 1 ft. deep, 0 ft. in perimeter and A sq. ft. in area, when passing an air volume of Q cu. ft. per minute. The airpower w kw. dissipated within the airshaft is computed by the formula: [ ] With a combined over-all unit efficiency of the fan and drive of E per cent, the air- shaft power requirements become [ ] There are 8760 hours per year, so with energy at I cent per kilowatt-hour the annual cost per kilowatt for continuous operation is $87.60; therefore, with energy at C$ per kw-hr. the annual airshaft power cost MI dollars per year becomes: [ ] which, expressed by the component parts, becomes : [] The amortization rate a dollars per year per dollar invested includes both depreciation and interest on the investment. These in turn involve the expected useful life of the airshaft and available monetary interest rate. For the purpose of this discussion the cost of airshaft sinking is assumed to comprise a fixed move-in charge Y dollars, which covers the cost of transporting, erecting and removing the shaft-sinking equipment and is independent of the air- shaft size. Also, it is assumed that the cost of shaft lining, if any, is fixed at $X per cu. yd. of lining material and that excava-

Jan 1, 1946

By Jed H. Mosgrove

One of the most interesting of all the subjects required of persons studying the different facets of coal mining is coal mine gases. Some mine gases have been a real problem since the very beginning of underground mining, and in the early days there was insufficient knowledge to cope with them. The history of mining shows that until about the last 50 years, much work was done primarily by the hand methods which are primitive by today's standards. Miners had to contend with gases without the aid of enclosed lighting, permissible mine machinery, sophisticated testing devices, and high-pressure ventilating fans. In early days the miners were not educated about the different mine gases nor did they have the technical equipment to determine the actual composition of the deadly atmospheres they encountered. They simply applied a descriptive term to each gas or mixture of gases depending on its effect on a person or the surrounding atmosphere. The gases or mixtures of gases were then referred to as "damps," a term which was probably derived from the German word "dampf," meaning vapors or gases. The more common damps encountered were : Blackdamp A condition of the atmosphere in which a miner's light would be extinguished and in which breathing would be difficult, sometimes even resulting in suffocation. An atmosphere deficient in oxygen which could contain a combination of any of the mine gases Firedamp A flammable mixture of methane and air which would either burn or explode when ignited. White Damp A mixture of gases containing carbon monoxide, most often found in mines during fires or after explosions.

Jan 1, 1981

By L. D. Stewart

The main reasons for developing an induction system for signaling from the cage are, first, to increase safety, and second, to effect economies in the operation of cage and ship hoists, especially when work is being done in the shaft. To-day nearly all mines which employ safe methods have installed safety gates on cages, at the different levels, and at the collar of the shaft. Under the old system in some instances signals could only be Given from the station outside the cage, and in other cases, after the signal was given the only method whereby those riding on the cage could control its movements consisted of pulling the bell-rope hanging in the shaft, an uncertain and somewhat hazardous procedure at best. With the system herein described, however, it is possible, without opening the gates, to signal to the engineer from any place in the shaft whether or not the cage is moving, and finder the same conditions it is possible to converse with the engineer by using the telephone. In short, the cage tender has at all times an opportunity either to signal or talk to the engineer without leaving the cage.

Jan 1, 1931

By D. M. Range

Exxon is reclaiming an 80 hectare (200 acre) Wyoming uranium tailings basin (10 Mt) in accordance with U.S. Nuclear Regulatory Commission requirements. The reclamation plan is designed to control the tailings and their radioactive emissions for at least 1000 years. Rigorous modeling and analyses of potential erosion by wind and water were used in planning. The use of riprap was minimized and the need for long term reclamation maintenance was eliminated. The resulting design is similar to erosionally stable regions created by nature. The concepts used in the design and implantation have wider reclamation application.

Jan 1, 1989