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By I. A. Lange, A. M. Richardson

Although methods for determining shaft lining thickness are well documented, little attention has been given to the design of station breakouts and other related shaft ground support structures. This paper discusses design of selected shaft structures for the Cathedral Bluffs project, a planned 54-kt/d (60,000-stpd) oil shale mine in western Colorado. Design philosophy and construction sequences used in the three completed 520-m (1700 ft) deep, 4.6-m (15 ft) to 10.4-m (34-ft) diameter shafts are described.

Jan 1, 1984

By Atsushi Sainoki

Blast vibration induced by mining activities, such as stope production blasts, could lead to the initiation of seismic events that inflict damage to mine openings. In this paper, the effect of stope production blasts on nearby fault is examined. First, validation of blast vibration attenuation is performed with a numerical model representing a single blast hole through comparison with that calculated from charge-weight scaling law derived from in-situ data. Subsequently, a mine-wide scale model with a fault parallel to a steeply dipping, tabular ore deposit that is mined out with sublevel stoping method is generated, and the stopes are extracted and backfilled with static analysis to simulate burst-prone conditions on the fault. Based on the stress states, dynamic analysis is performed, in which blast vibration is applied to grid points on a stope wall on the hanging wall side. This assumes 9 blast holes located close to the wall, and blast-induced particle velocities that consider the positional relationships between the assumed blast holes and the stope wall are applied. During the dynamic analysis, blast sequence is considered, and stress states and shear displacement on the faults are examined. It is found from results that, after a rise in normal stress on the fault due to compressive waves induced by the blasts, the normal stress decreases because of the reflection of the compressive waves on the fault. The reduction in the normal stress due to the reflected waves is found to be large enough to cause the fault to slip. The results also show that the level of normal stress eventually keeps decreasing with time as the blast sequence proceeds and that an increase in shear displacement on the fault is accompanied by a decrease in normal stress. This study clarifies the mechanism by which blast vibration causes the fault to slip. In addition, the simulation technique to apply blast vibration that takes into account blast sequence and the locations of blast holes to a stope wall is developed.

Aug 1, 2013

By R. Loj

Katowice Coal Holding (KHW) is one of the largest coal companies in Europe. The company owns five coal mines with a daily output of around 60 000 tons of coal. In the Katowice city area, very good quality steam coal is extracted. The depth of mining varies between 400 and 1100 m and some of the mines rank amongst those most afflicted by methane in the Upper Silesian Coal Basin, with the methane hazard having a significant impact on production and safety. ?Myslowice-Wesola? mine, being a part of the Katowice Coal Holding is characterized by high methane and rockburst hazards. The mine is equipped with a modern surface drainage pumping station. At the mentioned mine, longwall 514 was selected for analysis of its methane emission. The longwall was extracting the thick seam 501 (over 4 m), at a depth of over 900 m, which was subject to high stress and high gas concentration conditions. At a distance of about 50 m above, seam 501 is covered by thin seam 416. The strata between these two seams are sandstone and mudstone layers. In the floor of seam 501, with a thin shale interlayer, is located seam 510, which is the thickest (over 10m) and richest coal seam in the Upper Silesian Coal Basin. In longwall 514 and it?s vicinity, methane was the dominant risk. For this longwall three methods of classical gas drainage were carried out. At first, drainage was undertaken using long boreholes from a cross-cut at level 665 m, located far from the production panel. Later, it was performed using typical boreholes drilled from the ventilation gallery (tail gate road). Finally, it was undertaken using a degassing drift executed in the upper coal seam 416. All of these headings, ie. cross-cut level 665 m, the ventilation road and conveyor road in seam 501 and the degassing drift in seam 416, were equipped with media for drilling and proper drainage pipelines. Due to the high rockburst hazard and some problems with caving, several kinds of de-stressing and torpedo blasts were carried out in both coal seams and roof rocks. The subsequent analysis and experiments allowed the establishment of some general rules for carrying out degassing operations effectively. The effectiveness of a degassing drift was demonstrated. In some instances, the system allowed more than 70% of the total methane released to be captured and fed into pipelines. The aforementioned blasts had a marginal impact on methane emissions and the efficiency of degassing methods. Cyclic drilling and regular switching of boreholes in phase with the mining progress and working face advance were shown to be essential.

Aug 1, 2013

By M. D. Banus, M. B. Bever, A. K. Jena

The heals of formation at 78", 195, and 273°K of the ternary compound h3SbTe2 based on the elements and based on the binary compounds In Sb and [inTe have been measured. The heats of formation at these temperatlcres of the binary compounds In Sb and In Te based on the elements have also been determined. Heal contents and free energies of the three compounds have been calculated from 0° lo 80I)°K. The free energies of joyrrzalion, heats of formations, and entropies of formation at 298°K have also been calculated. The results shown that the tertnary compound is metastable with vespecl to InSh and ln Te below 696 °K. bul is slable above that temperature. The weaker bonding of results in a positice entropy of formation which with incrensirzg temperature makes increasing negative conlvihtclions to the free energy and above 696°K renders the compound slable. THE ternary compound In3SbTez occurring in the quasi-binary system In Sb- In Te' forms on cooling at 829°K by a peritectic reaction.' Observations at 673" and 573 K have shown that this ternary compound decomposes slowly into the binary compounds InSb and1n~e.l'' It has not been possible to analyze the metastable behavior of the ternary compound because up to the present time data on its thermodynamic properties have been lacking. Some information on the binary compounds, however, is available. The heat of formation of InTe at 273°K and its free energy at 673°K are kn~wn.~'~ The heats of formation of InSb at 78", 273', 298", and 723°K have been measured5-' and its heat capacity between approximately 12" and 300"Kg9l0 is also known. In the investigation reported here the heats of formation at 78% 195% and 273°K of the ternary compound In3SbTez have been measured. The heats of formation of the binary compounds InSb and InTe at these temperatures have been obtained by combining new calorimetric results with previously published data. The heat contents and free energies of the three compounds at various temperatures from 0" to 800°K have been calculated. Against the background of this information, the metastability of the ternary compound will be discussed. 1) EXPERIMENTAL 1.l) Preparation of Specimens. The materials used consisted of the elements indium, antimony, and tellurium, the binary compounds InSb and InTe, and the ternary compound In3SbTez. The elements, obtained from American Smelting and Refining Co., had a nominal purity of 99.999+ pct. The compound InSb was Cominco semiconductor grade; the compound InTe was prepared from the elements by melting under a vacuum of 10-h m Hg followed by slow cooling. Three batches of specimens of the compound In3SbTez were used. One batch was prepared by melting appropriate amounts of the elements in an evacuated and sealed Vycor tube. The melt was held at approximately 100°K above the liquidus for about 8 hr, shaken repeatedly, and quenched into a mixture of ice and water. The specimen was annealed in vacuum at 760°K for 4 weeks. In preparing a second batch, a mixture of the component elements was melted and quenched in water. The resulting ingot was powdered. The powder was pressed into pellets, which were annealed in vacuum at 748" to 773°K for 4 weeks. A third batch was prepared in the same manner as the second, except that the starting materials were InSb and InTe rather than the elements. Metallographic examination of samples of the three batches and X-ray diffraction examination of a sample of the second batch did not reveal evidence of microsegregation or a second phase. The results obtained with the three batches showed no systematic differences. 1.2) Calorimetry. The calorimetric method has been described in detail." Samples of the compound In3SbTez, mechanical mixtures of InSb and InTe in the proportion of 1:2, and mechanical mixtures of indium, antimony, and tellurium in the proportion of 3:1:2 were added to a bismuth-rich bath at 623°K in a metal-solution calorimeter. These additions were made from 78°K (liquid nitrogen), 195°K (dry ice and acetone), and 273°K (ice and water). The heat effects of the additions were measured. The difference in the heat effects of the additions of a compound and the additions of the mixtures of its constituents, adjusted for differences in the concentration of the bath, is the heat of formation of the compound. In the concentration range not exceeding 1.5 at. pct solute, the heat effect of the additions was a linear function of concentration. The heat of formation refers to the temperature from which the additions were made, namely, 78", 195", or 273°K. Several calibrating additions were made in each calorimetric run. The calculated heat capacity of the calorimeter and hence the calculated heat effects of the additions of samples depend upon the values adopted for the heat contents of the calibrating substance. In this investigation bismuth at 273°K was used and a value of 4.96 kcal per g-atom was taken for (HGZ3"k . 2) RESULTS AND DISCUSSION 2.l) Heats of Formation. The heats of formation of the ternary compound In~SbTez from the component elements indium, antimony, and tellurium and from

Jan 1, 1968

By Etienne Simode

When a fire breaks out in a mine access road, the hot smoke, due to heat transfer with the surrounding strata, progressively cools as it moves forward. Depending upon the resulting temperature distribution, the density of the fluid changes. This change will bring about: Firstly, a variation in the resistance of the roads, a static factor which will affect ventilation flow rates; Secondly, the appearance of extensive aerodynamic driving loads in the vertical and angled roads, a dynamic factor which can have an extensive impact on ventilation. Because of the appearance of combustion and distillation products, the vaporization of water, which wets the timbering and strata, and the expansion of gases, fluid rates can at times be increased tenfold in the area of the fire. These disturbances may cause explosions and ventilation inversions, which fill other working areas with smoke toxic to workers, and which can come up upon rescue teams from behind. Due to the progressive heating of the surrounding rocks, which will slow down heat transfer, these dangerous conditions change over time. At the Lorraine Basin Coal Mines, programs have been set up and employed for the computer simulation of these phenomena over time. They serve to anticipate or to understand such phenomena, the input data being the characteristic parameters of the mine ventilation network, the operating curve of the main fans, and measurements or estimates of some temperatures. Two programs, employed together, have been developed for these studies: One program, called RESO, calculates the distribution of flow rates and pressures throughout the entire network; The other, called FEUMIN, determines smoke temperatures over their entire path.

Jan 1, 1980

By Pollard D, Meadows N

The presence of impurities which are electropositive to zinc in acid zinc electro- lyte causes changes to deposit morphology and reduced current efficiency. Glue may be added to control some impurity effects, but assaying for animal glue concentration is difficult and seldom done. Measurement of the activation overpotential for zinc deposition by cyclic voltammetry is used in some plants to monitor electrolyte quality and control glue additions. The deposit morphology and current efficiency of zinc deposition from commercial electrolyte were investigated for various glue additions in the presence of increased levels of antimony. Cyclic voltammetry was invest- i,ated as a method of optimizing glue additions in the presence of antimony. Scanning electron microscopy showed deposits characteristic of the impurity element present and the glue addition rate. Cyclic voltammetry measurements showed some correlation between current efficiency and activation polarization potential. The importance of using tankhouse electrolytes where results are to be related to tankhouse operation was noted.

Jan 1, 1984

By Ben H. Daud

A computer model has been developed at Consolidation Coal Co.'s Central Engineering Dept. for preliminary economic evaluation of deep coal mine reserves. Since it was first formulated more than two years ago, the model has been used for the following purposes: (1) ranking studies of coal exploration projects, (2) marketing surveys, (3) preliminary sale and acquisition analysis of coal reserves, and (4) parametric analysis in conjunction with detailed feasibility studies.

Jan 1, 1979

By Juan Ares, Enrique Fernández, Alejandro Sanz, Francisco González

"INTRODUCTION Crossrail is a subsidiary company of Transport for London created for the construction of a new transverse train line 118 km long between Maidenhead and Heathrow in the West, and Shenfield and Abbey Wood in the East, including 21 km underground below London. Crossrail C305 Eastern Running Tunnels project is the biggest contract within Crossrail Project and involved boring 11.8 km of twin tunnels through London’s city center. Crossrail C305 Project interfaced with different contracts along its alignment and therefore logistics and solutions had to be developed to minimize disruptions or interferences with other contractors and the neighborhood. The paper describes this innovative approach. C305 CONTRACT APPROACH C305 contract was split into three drives, to be excavated by four EPB TBMs 7.1m diameter, as shown in Figure 1. •,Drive Y: 8.2km long between Limmo Peninsula and Farringdon Station in the city center •,Drive Z: 2.7km long between Pudding Mill Lane and Stepney Green Junction •,Drive G: 0.9km long between Limmo Peninsula and Victoria Dock Portal in the East. Crossrail C305 Project scope of works included the excavation of TBM tunnels and shafts at Limmo Peninsula and Stepney Green (including 17m span turnout caverns), along with the requirement to traverse station and shaft structures of other Crossrail contracts. Limmo Peninsula Site was a strategic element as it was the only access point on the tunnel alignment with sufficient available area at the surface for tunnelling logistics and also connected to the Lea River, tributary of the River Thames which facilitated marine operations for segment supply and muck removal. These were the reasons for operating Drive Y & Drive G TBMs from that location. Drive Z TBMs were originally planned to be launched from Stepney Green to Pudding Mill Lane, supplying the TBMs during Drive Z excavation from Limmo Peninsula site through the excavated section of Drive Y between Limmo and Stepney Green. During the early stages of the project, a value engineering proposal with a new tunneling strategy was agreed wherein the Pudding Mill Lane contractor would provide space for TBM assembly and operation in their portal, allowing for reversing Drive Z excavation and launching the two TBMs from Pudding Mill Lane. This optimization reduced some of the shaft requirements at Stepney Green which were contingent upon critical enabling works and provided program certainty and cost savings for the full Crossrail Project. It allowed for the reuse of both the Drive Z TBMs for Drive G excavation from Limmo to Victoria Dock Portal thereby saving on the procurement of two TBMs, in addition to easier logistics for both Drives Y&Z, therefore de-risking the TBM excavation process and the C305 Project program completion."

Jan 1, 2016

By Paul McAnuff, Alastair Grogan

In Canada, the only vibration regulations which apply across the entire country are intended to protect fish spawning areas. The Provinces and Territories regulate mines and quarries, and are responsible for setting vibration and airblast regulations. Some Provinces have set specific regulations, while others leave these restrictions to the mines inspectors who can set limits on a case by case basis. For the most part, it is left to individual municipalities to regulate blast vibrations and airblast from other blasting activities, which differ from jurisdiction to jurisdiction, and in some cases are not enforced. Blasters working in different jurisdictions have to be aware of the applicable regulations for the area they are working.

Jan 1, 2005

By W. W. Adams

[The quantity of explosives sold in the United States in January, 1931, for domestic consumption, amounted to 368,100 kegs (9,202,510 pounds) of black blasting powder, 4,810;000 pounds of permissible explosives, and 16,533,000 pounds of high explosives other than permissible. These figures are based on reports received by the United States Bureau of Mines, Department of Commerce, from nearly all manufacturing companies, and include an estimate of sues by several companies that do not furnish monthly reports. Reports actually received from manufacturers shored sales of 365,977 kegs of black blasting powder (consisting of 220,892 kegs of granular powder and 145,085 kegs of pellet powder), 4,687,900 pounds of permissible explosives, and 15,498,152 pounds of high explosives other than permissible. Sales in January, 1931, were smaller than in January last year, the decreases being 14 per cent for black blasting powder, 19 per cent for permissible, and 17 per cent for high explosives other than permissible. Sales in January 1931 when compared with soles in December 1930, show increases for all three classes of explosives as follows: 2 per cent for block blasting powder, 16 per cent for permissible explosives, and 7 per cent for other high explosives. PERMISSIBLE EXPLOSIVES: Of the 4,687,900 hounds of permissible reported sold during January, 97 per cent was used for coal-mining operations, Including 32 per cent for anthracite mines and 65 per cent for bituminous mines. The following Staten were the largest users of permissible explosives daring January: Pennsylvania, West Virginia, Illinois, Alabama, Kentucky, Indiana, and Utah. Their combined sales represented 89 per cent of the entire sales reported for this class of explosives.]

Jan 1, 1931

When the HSE Act was introduced in New Zealand in April 1993, one of the prime aims of the Government was to signal to the industry. The Government's recognition of the employer as the key person responsible for safety and health in the workplace and to actively encourage employers to self manage the health and safety function. Because of the significant change in the philosophy behind the new legislation, and because of the inherently conservative nature of the mining industry, it has taken some years for both the industry and the regulators to reach the stage of considering the framework in which a controlled degree of self management can proceed.   In this paper, some of the issues relating to the legitimacy of the process are considered, some of the questions raised in the minds of those charged with implementing the legislation are discussed, and the views of some eminent authors are examined.   The latter part of the paper focuses on a programme called the Reduced Site Surveillance Programme, which grew out of Goal 2 of the New Zealand Mining Inspection Group's 5-Year Strategic Plan. The programme is described in some detail, and the criteria applied at each stage of the programme is discussed. The paper concludes with the author's expectations of the longer term outcomes of the programme.

Jan 1, 1997

By Ho-Tun E, Stewart PSB

The definition and recognition of silver minerals is very difficult. In general such minerals occur at low concentration and can be hard to identify and measure using conventional optical mineralogy. The present paper describes the use of the QEM*SEM system to tackle this problem and provide information of use to the metallurgist. Three aspects of QEM*SEM are used to special advantage in this application. Firstly the automated mode of operation is used to make a rapid search for the sparse phases. Secondly the X-ray capability is used to identify the mineral phases. Finally the image analysis programs quantify the distributions of the minerals which are found. The paper deals with the identification stage of the process and with the use of the data which can be derived. Silver minerals which covered a range of ore types and composition were collected and studied in detail. On the basis of these measurements and information received from a number of mining companies regarding the important minerals, a classification table was prepared. This table listed about 40 different silver mineral types which could be identified by QEM*SEM and which were of interest in silver recovery processes. Where the silver occurs in solid solution in concentrations greater than about one per cent, the silver content in the species was subdivided into ranges based on statistical intervals. The QEM*SEM system was programmed to recognise these as separate species. Examples are presented of the use of the system in defining the type and morphology of the silver mineralisation to assist in the assessment of batch flotation test Samples.

Jan 1, 1993

By I. E. Odom

An electron optical and microprobe study was made to determine the physical and chemical nature of the silica minerals that occur as natural impurities in bentonite and montmorillonitic fuller&apos;s earth clay products (both granular and powder) and that occur in <10-µm dusts from plants that process these products. The purpose of the study was to determine if discrete "free" silica minerals, such as quartz, could be observed using SEM and EDS methods. No “free" silica minerals could be observed in the SEM images of the granular and powdered products, either among or on the surfaces of the particles. Also, no “free" silica could be identified by either SEM or EDS analyses of the dusts, even though quantitative X-ray diffraction analysis indicated that trace amounts of quartz occurred in all samples. It was determined that these quartz and other silica minerals were encapsulated or coated by montmorillonite. Vigorous washing, however, removed some of the clay coatings, so that small amounts of silica minerals could be seen by SEM and EDS analysis. It was found that all primary crystalline quartz grains in the bentonites have diagenetic overgrowths consisting of a mixture of montmorillonite, opaline silica and possibly microcrystalline quartz. Detrital quartz grains in the fuller&apos;s earth have thin diagenetic overgrowths of opaline silica, also containing montmorillonite. The clay encapsulation of the silica minerals in the products studied, as well as in the potentially respirable (<10-µm) dust produced during manufacturing of bentonite and montmorillonitic fuller&apos;s earth clay products, is considered to be an important factor influencing the potential health effects (e.g.. silicosis) of the contained silica. Even if clay dust containing silica should be inhaled, the montmorillonite encapsulating the quartz and other silica minerals would prevent direct contact of the silica with lung tissue. The clay encapsulation of quartz, as well as the highly hydroscopic nature of montmorillonite, may explain why not a single confirmed case of silicosis has ever been reported among plant workers in more than 65 years of production.

Jan 1, 1998

By J. D. MacKenzie

THE world production of copper for the first eight months of 1927 shows an increase of 3 per cent over the same period in 1926. Since February of this year, however, production has been considerably curtailed. The United States reduction in the last four months has been offset by the increased South Ameri-can and Belgian Congo production. The United States is now producing 58 per cent of the world production, Chile and Peru 17.3 per cent, Belgian Congo 5 per cent. In 1926 the United States produced 54 per cent, Chile and Peru 16.3 per cent, Belgian Congo 6.3 per cent. Production, Tons 1917-largest war year 1,580,000 1925 1,581,000 1926-increase 3 per cent 1,628,000 1927-increase 3 per cent 1,670,000 Copper Producing Countries, 8 mo., 1927: Tons Per Cent United States 644,000 58.0 Chile and Peru 192,000 17.3 Europe 90,000 8.1 Belgian Congo 56,000 5.0 Japan 46,000 4.1 Mexico 30,000 2.7 Canada 23,000 2.1 Figures are not available for Spain and Portugal, which would probably precede Mexico.

Jan 12, 1927

By William Porter

Hand scaling is a physically demanding job and is responsible for numerous overexertion injuries in mining. This experiment studied rib scaling from an elevated bucket to examine force generation capabilities and electromyographic responses to a prying subtask. Subjects exerted force using two bars (steel and fiberglass) at five target heights. Work height significantly affected peak prying force during scaling activities with highest force capacity at the lowest level (p = 0.0188). Bar type did not affect force generation (p = 0.7843): However, use of the fiberglass bar required significantly more muscle activity to achieve the same force (p < 0.05). It was concluded that miners should scale points on the rock face that are below their knees, and reposition the bucket as often as necessary to do so. Additional research is needed to fully understand the impact of bar type on the physical demands of an entire scaling task.

Jan 1, 2006

By H. M. Morse

This report on oil and gas development in Mississippi covers the period from Jan. I, 1944, to Dec. 31, 1944: Salt Domes During the year six salt domes were drilled for sulphur, but no commercial sulphur deposits were found. One salt dome, the Bruinsburg, in Claiborne County, has produced gas- at 935 to 940 ft&apos; in Moody&apos;s Branch marl. The Stringer salt dome in Smith County and the Ruth salt dome in Lincoln County both had a slight showing of heavy oil. Other salt domes have been dry. In addition to the Bruinsburg dome, the Allen salt dome, in Copiah County, and the Richton salt dome, in Perry County, were discovered in 1944; also the Sumrall dome, in Covington County. New Oil Fields Baxtemille Oil Field.—The Baxterville oil field was discoveredby the Gulf Refining Co, in sec. 7, T. I N., R. 16 W., Lamar County. At the end of the year this field had one oil well, with two active operations. Production for 1944 was 1047 bbl. of oil. GwinvilLe Field.—Gwinville field was discovered by S. W. Richardson, in sec. 24, T. 9 N., R. 19 W., Jefferson Davis County. This discovery well was a gas-distillate well, the oil being crystal clear. At the end of 1944 there were two gas wells and one oil well in the field. The oil well is approximately 2 1/2-miles from the gas- distillate wells. Gas production was 55,801 M cu. ft. and the distillate production was 2644 barrels. Heidelberg Oil Field.— The Gulf Refining Co. discovered the Heidelberg field in sec. 30, T. I N., R. 13 E., Jasper County, in January 1944. This field has by far exceeded the other 1943 and 1944 discoveries, having approximately 56 oil wells, 7 dry holes, and 10 active wells at the end of the year. Production to Jan. I, 1945 was 1,441,192 bbl. of oil. Mallalieu Oil Field.—The california Company discovered the Mallalieu oil field in set. 10, T. 7 N., R. 8 E,, Licoln. County. At the end of the year there was one well in the field with three active operations. Production was 32,303 bbl. of oil. Old Oil Fields Brookhaven Oil Field, in Lincoln County, has one oil well, which produced 2590 bbl. of oil during 1944. CarY Oil Field, Sharkey County1 has only one producing well, which produced 11,818 bbl- of oil during the Year- In Cranfield Oil Field, dams County, II oil wells and two gas-distillate wells were drilled in 1944 and there were five active wells on Dee. 31, 1944- The total production for the Year was 5251422 bbl-of oil. The gravity of the oil is 40" to 54.9&apos;- In Eucutta Oil Field1 Wayne County1 34 oil wells were completed during 1944. There were five dry holes and six active wells at the end of the year.. The field produced 454,332 bbl. of all d the average gravity is 25" Flora Oil Field, Madison County, pro-

Jan 1, 1945

By S. J. Mitchell

An analysis of bolting reinforcement of several large [approximately 18 m (60 ft) cube] pillars was performed. The many overcoring stress profiles in pillars at the mine were used to produce generalized stress distributions at various stages in pre- and post-failure. A complete stress-deformation curve was estimated from this data. The effect of pillar bolting on the load-deformation behavior was extrapolated from the observed unbolted behavior. Bolting can increase pillar strength by up to 10 percent. The effect of bolting on general mine stability was examined with a short computer analysis. The computer model was calibrated against measurements performed at the mine, and produced good agreement between measured and modeled stresses. The analysis indicated that bolting increases the bolted pillar safety factors in the event of additional pillar failure by a small amount (approximately 5 percent). Progressive pillar failure is unlikely, because arching transfers most load from yielding pillars to large unmined abutments rather than to the smaller panel pillars.

Jan 1, 1984

By W. T. Olsen, R. Ulcer

WHEN a liquid alloy freezes, the solid first formed usually differs widely in chemical composition from that last formed, so that there is segregation in the alloy as cast. For example in the copper-nickel system (fig. 1) the first solid formed from a liquid containing 55 atomic pct Cu may contain as little as 38 pct Cu, while the last must contain well over 55 pct. Three factors may act to decrease segregation from the maximum possible. 1. Diffusion in the cooling solid tends to make the phase homogeneous, decreasing segregation. This may be important at slow rates of cooling. 2. Segregation is impossible without diffusion in the liquid. At extremely rapid rates of cooling there may not be enough time to allow maximum segregation. 3. Supercooling delays nucleation to temperatures well below the liquidus thereby decreasing segregation. Hence the first nucleus in the copper-nickel system may contain well over 38 pct Cu. At sufficient supercooling the first nucleus may form below the solidus, in which case there is no reason to expect any segregation whatever. From these considerations, we could predict that at sufficiently low rates of cooling the alloy would be unsegregated because of factor 1 and at sufficiently high rates of cooling there should also be no segregation because of factors 2 and 3. Considerable segregation should occur only at intermediate rates of cooling. We have demonstrated experimentally that segregation can be completely suppressed by rapid rates of cooling. For the alloys studied, however, these rates are too great to be attained in any commercial practice. An alloy of 55 atomic pct Cu, 45 atomic pct Ni was frozen by cooling at varying rates. The degree of segregation in the solid was determined by X-ray diffraction photographs. Slow rates were obtained by slowly cooling the furnace containing the liquid alloy; fast rates by pouring or ejecting droplets of the alloy into water or iced sodium hydroxide solutions. The cooling rate of the droplets can be cal-culated from their dimensions by assuming reason- able values of thermal conductivity.&apos; The experi-ments were repeated with an alloy of 16.5 pct Cu and 83.5 pct Au. A single experiment also showed a 50 atomic pct Bi-Sb alloy had no segregation at the most rapid quench. The position of back-reflection X-ray diffraction lines is a highly sensitive function of the lattice constant, which in turn depends on the chemical composition of the phase. A phase of varying composition will give broad diffraction lines. By measuring the edges of these lines and making suitable corrections for intrinsic line width, it is possible to determine the range of lattice constants represented. These can be converted to chemical compositions from a lattice constant vs. composition curve. Results are shown in table I. In the copper-nickel system the greatest segregation is found at the slowest cooling rates, where the lowest percentage of copper theoretically possible is found. In the copper-gold system, on the other hand, the degree of segregation is decidedly less at the slowest rates of cooling, being greatest at 11,100°C per sec. At no rate is the theoretically lowest percentage of copper (12 pct) found. At the rates of cooling found in sand and die castings the degree of segregation is large and depends little on the rate of cooling. Acknowledgment Most of the material in this paper is abstracted from a thesis presented by William T. Olsen, Jr. in 1948 in partial fulfillment of the requirements for the degree of Master of Science at the University of California.

Jan 1, 1951

By V. Alexandrov

This paper presents the results of theoretical investigations of the energy requirements of the hydraulic lifting of mined materials from the seabed to the sea surface in the deep-sea mining of solid minerals such as manganese nodules in the Clarion-Clipperton region of the Pacific, situated on the sea floor in water depths of 4,500 m or more. The principal element of the developed underwater transport system is the Underwater Chamber, which is connected by flexible pipeline to a mining machine that gathers nodules from the seabed, mixes them with seawater, and feeds them into a flexible pipeline. In this paper, we discuss the question of the optimum water depth for placement of the Chamber, the interior of which is designed to maintain a 1-atmosphere pressure. We present a method for calculating this depth as it relates to the mechanical characteristics of solid particles, the shapes and size distributions of the particles, particle and slurry density, and other properties. These investigations were carried out in hydro-transport laboratory of the Saint-Petersburg Mining Institute and the hydraulic laboratory of Faculty Environmental Engineering in Wroclaw Agricultural University. KEY WORDS: deposit, nodule, flexible pipeline, pressure drop, concentration, hydromixture

Jan 1, 2005

By John D. Warne

"INTRODUCTION Initiated as a part of the Bureau of Mines program for development of strategic minerals for national defense, Investigation of the fluorspar deposits of the Northgate area was begun in June 1944 and completed in March l946. Mining Operations were active in the district during most of the period of investigation.The Fluorspar, Fluorine, and Camp Creek mines develop the two more promising vein systems known in the area, the Fluorspar group of claims covering one vein system and the Fluorine and Camp Creek groups the other. Figure 1 shows the location of the properties. The Fluorspar and Fluorine properties were operated (except during the winter months) by the Western Fluorspar Corp. The Camp Creek mine was operated during 1943 and 1944 by Kramer Mines, Inc.The properties were examined April 20 and again November 4 to 12, 1943, by C. R. Wilfley, a Bureau of Mines engineer, who recommended work to determine ore reserves and to serve as a guide for development. Investigations by the Bureau of Mines covered all three properties."

Aug 1, 1947