Search Documents

By E. C. Potter

FUEL-OIL was first substituted for coal at these works in September, 1888. It was first applied in the converting-department to the battery of boilers, consisting of 14 tubular boilers, 16 feet in length by 5 feet in diameter. To operate these boilers with coal for 24 hours required 14 strikers, 3 ash-wheelers, 6 men unloading coal, and 2 water-tenders, making a total of 25 men. With fuel-oil the same boilers require for the same period 2 water-tenders and 4 men to attend to the burners, making a total of 6 men. This gives a saving of 19 men, which, at an average of $2 per day each, amounts to $38 per day. Comparing the consumption of oil with that of coal, we find that for the week ending January 5, 1889, with an ingot output of 6403 tons, 2731 barrels of fuel-oil were used as against a necessary consumption of coal for the same work of 848 tons, showing 3.22 barrels of fuel-oil to be equivalent to one ton of Indiana block-coal. Figuring oil at 60 cents per barrel, and coal at $2.15 per ton, we have as the cost of oil $1.93, as against $2.15 for its equivalent in coal. In December, 1888, the rail-mill battery of 26 boilers, of the same dimensions as those in the converting-department, was equipped for fuel-oil. For the week ending January 5, 1889, with a rail out-put of 5208 tons, 5987 barrels of oil were consumed, as against a necessary consumption of coal, to do the same work, of 1805 tons, showing 3.31 barrels of fuel-oil to be equivalent to one ton of Indiana block-coal, which at the costs named above would show $1.98 worth of fuel-oil to he equal to $2.15 worth of coal. The labor required to operate the rail-mill boilers for 24 hours, with coal as fuel,is: 26 stokers, 4 water-tenders, 6 ash-wheelers, 12 men unloading coal; total, 48 men. With oil as fuel, the same work requires 4 water-tenders and 6 men to attend to the burners; total, 10 men; a saving over coal of 38 men in 24 hours, which, at an average price of $2 per day, would be $76 per day. In the brief experience we have had with oil as fuel, we find that the efficiency of the boilers is somewhat increased and the repairs are

Jan 1, 1889

By Homer S. Frankhouser

Materials may be dredged, processed, stored and loaded for shipment at a single site in water depths ranging from 250 to 1200 ft. Solution mining may also be accomplished in deep sea situations. And, open air subsea mines with direct surface access may be developed and worked under the ocean floor. These concepts for deep sea mining are the results of extensive testing of individual components of the proposed systems by Dravo Ocean Structures, Inc., a subsidiary of Dravo Corp. A basic structure in these systems is the articulated platform. The platform consists of a gravity- type base and a buoyant cylindrical column which is constructed at an onshore location, towed to the offshore site and installed in a matter of days without use of heavy equipment. The base is also buoyant for towing purposes. This allows for gradual flooding to the point of negative buoyancy for positioning and anchoring to the ocean floor.

Jan 1, 1971

By AIME AIME

ALTHOUGH the present economic depression is felt in the petroleum industry, probably as much as in any other branch of American industry, the Petroleum Section of the Institute was well represented at the general sessions on Monday and at all of the seven division sessions on Tuesday, Wednesday and Thursday. The seven sessions of the Division were so arranged as not to conflict and thus permitted members to hear the programs of all sessions.* The first meeting of the Petroleum Division was held on Tuesday afternoon; a joint session on engineering research and production engineering. The following papers were presented:

Jan 1, 1931

By C. J. Beevers

Tlze influence of zirconium hydride precipitate mprphology on the fructure of Zr-H alloys tested at strain rates of 10- sec at 20° and - 196°C and at strain rates of -500 sec.-1 at 20°C has been inves-tigated. The critical stage in the embrittlement of these alloys was the fracture of the zirconium hyhide precipitates to form large interval cracks at a stress of 25,000 10 137,000 psi. In specimens con-temping up to 100 ppm H the preciptates existed as isolafed platelets in the zirconium matrix and their fracture as enhanced by low temperature (—196°C) and high strain rate (-500 set-f) loading. These resl~lts lead to the conclusion that the rate of strain hardening of the zirconium metal controls the frac-tzrm of the hydride platelets. Increased hydrogen contents of 500 to 2000 ppm resulted in an increase in the 1)volume fraction and size of precipitates and crlso led to crack propogation in the hydride at both 20 and —196C at the low strain rates (10'* sec-'). Quenching led to refinerment of hydride precipitate size and reduced the degree of embrittlement at — 196°C; this effect is attributed to the absence of fracture of the fine precipitates. The formation of zirconium hydride precipitates has been shown to be the cause of hydrogen embrittlement of zirconium.' Several investigators'-" have studied the problem in broad outline, demonstrating that impact-loading conditions, testing temperatures below room temperature, and increasing hydrogen content produce increased brittleness. For example, Muehlenkamp and schwope2 showed that the transition temperature for notched impact tests was raised from 150" to 350°C on increasing the hydrogen content from 45 to 490 ppm. The degree of embrittlement is also controlled by the morphology of the zirconium hydride precipitates. The solubility of hydrogen in zirconium decreases from 600 ppm at 550°C to 10 ppm at 20"C,~ so that the form of the zirconium hydride precipitates (ZrH2) can be modified by varying the cooling rate through the Zr-aZr + ZrH2 phase boundary.= Forscher showed that quenching a specimen containing 35 ppm H from above 315°C resulted in a reduction in area of 70 pct at -196"C, whereas slowly cooling from above 315°C resulted in a ductility of half this value. The role of the hydride precipitate in the fracture process has been examined by Young and schwartz6 and more recently by westlake.' From metallo-graphic observations on slowly cooled Zr-H alloys they have suggested that cracks are nucleated in the hydride precipitates by the interactions of twins in the zirconium metal with the hydride. The experiments reported in this paper show that crack propagation in the zirconium hydride precipitates is the critical stage in the embrittlement of Zr-H alloys. The factors influencing fracture of the hydride precipitates and crack propagation in the zirconium metal will be related to the problem of embrittlement. EXPERIMENTAL TECHNIQUES The zirconium used in these experiments was produced from an ingot of vacuum arc-melted iodide zirconium forged down to 1 in. diameter at 800' to 850°C. The 1-in.-diameter bar was surface-machined and cold-swaged to 0.375 in. diameter. After a vacuum anneal at 800°C for 1 hr the hardness was 60 to 70 Vdh. The total impurity content was approxi-

Jan 1, 1965

By B. C. Blake

IN general, billet-type or long slender ingots are used when it is desired to produce directly from the ingot in one conversion a product of medium or small cross-sectional area. They are designed to eliminate the blooming and billet-mill stages of the usual procedure. As used at Connors, they constitute a means of keeping a continuous rolling mill busy in the production of high-quality small rods, small angles, hoop stock, baling ties and concrete reinforcing rods without the need for a blooming or billet mill. They represent sound steel with the best surface that is commercially practical to use in the rolling of small continuous mill products.

Jan 1, 1947

By Arthur Wade

The most important development in connection with the search for oil in Australia during 1940 was on the legislative side. Prior to 1939 legislative enactments in the various states with regard to prospecting for petroleum were such as to prohibit large-scale effort and to bar the major oil companies from operating. The preparation of the Wade Model Bill for the Commonwealth Government in 1939 and the acceptance of the Bill in principle by all States, has gone far to remove these obstacles. Amending Acts, largely based on the Alodel Bill, have now been passed by all States with the exception of New South Wales and Tasmania. In New South Wales an Amending Bill is being drafted, while the Govern-ment of Tasmania is preparing to introduce an Amending Bill provided there is any demand for it. Noteworthy developments followed immediately on the passing of these Amending Acts. The Shell Company (1)1 and the Superior Oil Company of California (2) too$ up large areas in Queensland and com-menced work during 1940. Caltex acquired a big tract of country in the Kimberley district of Western Australia (3) and has made application for an area in the Territory of Papua. An Australian company, The Phoenix Oil Extraction Co., has obtained a permit to prospect over an extensive area bordering the south coast of Western Australia (4). Other developments are foreshadowed. The Shell Company is making an intensive examination of its area in Queensland (I). Geological, geophysical and aerial surveys are in progress. Caltex has three geological parties in the held in Western Australia while Superior Oil Company of California has done some geological work in the interior of Queensland (2). None of these concerns envisages a drilling campaign in the near future. Much exploratory work is necessary. Further work has been done by the companies that were already operating in 1939, though an important Australian company - Oil Search—has abandoned the work of prospecting in Australia. This company has subleased its holdings, at North West Cape in Western Australia (;), to Caltex on a royalty basis. The company also maintains its holdings in, and connection with, the Australasian Petroleum Company Proprietary Limited, which is a combination of Standard Oil (New Jersey), Anglo-Iranian and Oil Search. This company is operating in the territories of Papua and New Guinea. Drilling Victoria.—Although a good deal of drilling was done in the LaBes Entrance Tertiary Basin of Victoria (7), no appreciable production of oil was obtained. In order to test the extent and possibilities of the oil-bearing sand in this region, the Commonwealth and State Governments jointly put down six scout boreholes to depths of between 1200 and I500 it. The results were nega tive. A deeper exploratory horehole put down by the Governments at Seacornbe, or 26

Jan 1, 1941

By Arthur Wade

The most important development in connection with the search for oil in Australia during 1940 was on the legislative side. Prior to 1939 legislative enactments in the various states with regard to prospecting for petroleum were such as to prohibit large-scale effort and to bar the major oil companies from operating. The preparation of the Wade Model Bill for the Commonwealth Government in 1939 and the acceptance of the Bill in principle by all States, has gone far to remove these obstacles. Amending Acts, largely based on the Alodel Bill, have now been passed by all States with the exception of New South Wales and Tasmania. In New South Wales an Amending Bill is being drafted, while the Govern-ment of Tasmania is preparing to introduce an Amending Bill provided there is any demand for it. Noteworthy developments followed immediately on the passing of these Amending Acts. The Shell Company (1)1 and the Superior Oil Company of California (2) too$ up large areas in Queensland and com-menced work during 1940. Caltex acquired a big tract of country in the Kimberley district of Western Australia (3) and has made application for an area in the Territory of Papua. An Australian company, The Phoenix Oil Extraction Co., has obtained a permit to prospect over an extensive area bordering the south coast of Western Australia (4). Other developments are foreshadowed. The Shell Company is making an intensive examination of its area in Queensland (I). Geological, geophysical and aerial surveys are in progress. Caltex has three geological parties in the held in Western Australia while Superior Oil Company of California has done some geological work in the interior of Queensland (2). None of these concerns envisages a drilling campaign in the near future. Much exploratory work is necessary. Further work has been done by the companies that were already operating in 1939, though an important Australian company - Oil Search—has abandoned the work of prospecting in Australia. This company has subleased its holdings, at North West Cape in Western Australia (;), to Caltex on a royalty basis. The company also maintains its holdings in, and connection with, the Australasian Petroleum Company Proprietary Limited, which is a combination of Standard Oil (New Jersey), Anglo-Iranian and Oil Search. This company is operating in the territories of Papua and New Guinea. Drilling Victoria.—Although a good deal of drilling was done in the LaBes Entrance Tertiary Basin of Victoria (7), no appreciable production of oil was obtained. In order to test the extent and possibilities of the oil-bearing sand in this region, the Commonwealth and State Governments jointly put down six scout boreholes to depths of between 1200 and I500 it. The results were nega tive. A deeper exploratory horehole put down by the Governments at Seacornbe, or 26

Jan 1, 1941

By Scott Turner

PRESIDENT SCOTT TURNER officiated as chairman of the opening session on mining methods, Monday morning, Feb. 15. The first paper was that of Max H. Barber on open-pit mining in the Lake Superior district, read by C. F. Jackson. W. L. Taylor stated that liquid-oxygen explosive had been tried but that the operators are satisfied with the explosives used; lb. of dynamite breaks one ton of rock. Although black powder is considered the most effective explosive, the factor of safety has decided in favor of high explosives. Lucien Eaton told of the Michigan Lime and Chemical Co.'s large L. 0. X. plant at Rogers City, Mich. Mr. Turner referred to this plant, also said that the Bureau of Mines is shortly to issue Bulletin 349 completely covering the use of L. 0. X. from its inception. W. D. B. Motter, Jr., gave some items concerning Chuquicamata, Chile. Twelve years ago the blasts moved 850,000 to 1,000,000 tons, but average shots now move 250,000 to 300,000 tons. One pound of L. 0. X. breaks 3.7 tons, against 3.1 tons by dynamite. Another speaker told of some large dynamite blasts in open pits, one of 360,000 Ib. in March, 1931, and another of 430,000 lb. to be shot in 1932. Tests have been made to determine the effect of large shots on the surrounding country. Mr. Taylor said that 4- and 5-yd. shovels were preferable to those of 8 yd.; their performance is better and cost is lower.

Jan 1, 1932

By G. Thodos, R. B. Grieves

A method has been developed for the accurate calculation of the cricondentberm and cricondenbar temperatures of multicomponent hydrocarbon mixtures of known composition. The mixtures may contain any number of components including paraffins and isoparaffins, olefins, acetylenes, naphthenes and aromatics. This approach is based upon the mole fraction of the low-boiling component in the mixture and graphically presents the ratios of the cricondentherm and cricondenbar temperatures to the pseudocritical temperature as {unctions of a boiling-point parameter. The only requirements are the critical temperature, normal boiling point and the approximate vapor pressure behavior of each component. For mixtures of more than two constituents a stepwise calculation procedure is necessary where the pseudocritical temperature is based upon the critical temperature of the pure low-boiling component and upon the actual cricondentherm or cricondenbar temperature of the mixture of all the remaining higher-boiling components. From an analysis of 22 binary systems (123 compositionsl, the average deviation of calculated cricondentherm temperatures from reported values is 0.87 per cent, based on degrees Rankine; and for 10 multicomponent mixtures containing from three to six components, the average deviation is 0.98 per cent. From an analysis of 18 binary systems (104 compositions) the average deviation of calculated cricondenbar temperatures from reported values is 0. 79 per cent; and for 15 multicomponent mixtures, 1.47 per cent. Equations, derived from the graphical relationships, are presented which enable rapid calculations for both binary and multicomponent systems. INTRODUCTION With the increasing tendency towards the use of high pressure processes, the need for an accurate method of calculation of the properties of a multicomponent hydrocarbon mixture in the critical region is becoming more essential. Critical region phase relations are also significant in gas condensate reservoirs, for which a knowledge of the fluid phase boundaries and regions of retrograde condensation make it possible to evaluate optimum operating conditions. The possibility of liquefaction in the underground structure may be established, and information on the feasibility of the use of repressurizing may be determined. A typical phase diagram for a multicomponent hydrocarbon mixture is presented as Fig. 1. This figure also shows the regions of retrograde behavior encountered by following lines AB and AC. If accurate methods of calculating the temperatures and pressures at the critical, cricondentherm (maximum temperature) and cricondenbar (maximum pressure) points of multicomponent hydrocarbon mixtures of known composition were available, it would be possible to estimate closely the entire phase diagram of any mixture. Several methods have been presented in the literature for the estimation of the critical temperatures and pressures of multicomponent mixtures containing all types of hydrocarbons and including the fixed gases.4-8,21 Considering the cricondentherm and cricondenbar points, the work is more limited. Etter and Kay5 have developed rather complex equations for

By E. L. Tucker

PREVIOUS investigations of E. L. Tucker and R. E. Head' related in particular to the effect of cyanogen compounds on galena, sphalerite, and pyrite, and their behavior in the presence of such com- pounds. The present contribution deals with the float- ability of the copper minerals and of pyrite. All experiments were performed on minus 200-mesh material, the method of preparation being the same as that described in the previous article. Flotation tests were made in a small mechanically agitated machine of 50-g. capacity designed in this laboratory by Gates and Jacobsen." General Naval Stores pine oil No. 5 and potassium xanthate were used in constant amount in all of the experiments; these agents were selected because of their present wide use in the flotation of copper minerals. Lime additions were varied to secure four 'final hydrogen ion concentrations, namely, neutral, 0.0005 per cent CaO, 0.003 per cent CaO, and 0.02 per cent CaO. The variation in lime addition was introduced to include the range of alkalinities employed in actual flotation practice.

Jan 1, 1926

By H. S. Munroe

The dressing-works of the St. Joseph Lead Company were destroyed by fire, February 26th, 1883. Within about four months, or on July 5th, 1883, the new mill, with a capacity of 500 tons per day, was built and in active operation. The capacity of the new mill has since been increased to 800 tons per day. The old mill was built in 1867, by Mr. C. B. Parsons, the present superintendent. It was a curious rambling old structure, which had grown with the demands of the business; a few jigs having been added in one place, a table or two in another and wings and sheds added to the main buildings, from time to time, as it was found necessary to increase the efficiency or the capacity of the mill. The old mill was, moreover, a most interesting place to the student, a perfect "museum of ore-dressing." Nearly every form of dressing apparatus known to the art had, at one time or another, found a place under its roof, jigs of many kinds, concave, convex, side-bump and stationary tables, tyes, buddles, dolly-tubs, etc., etc. The method of dressing followed in the main the lines of English practice, but with many modifications, both in the machinery and the methods of working, due to the inventive genius of Mr. Parsons. Different forms of crushing apparatus were tried, and the best method of handling the ore and the different products of

Jan 1, 1889

By Dogan E. Gücer

In the following note, with the help of a new parameter of strain hardening, the attention is drawn to the close relationship between the relative performances of steels under plastic range cycling and their strain hardening characteristics. If a cantilever beam of rectangular cross section is tested with the arrangement shown in Fig. 1 in reversed bending between constant deflection limits at the lever head, the longitudinal strain-deflection hysteresis shown in Fig. 2 is obtained. There is no lateral strain due to constraint at the rectangular test section.' If the absolute value of strain undergone between a maximum state of tension and maximum state of compression is called A, it will be seen that A decreases with cycling rapidly due to the strain hardening in the test section and the ensuing change in the bent beam profile. It will also be seen that A reaches an approximately stable value around 10th cycle. If we call the first cycle strain range, A,, and that of 10th cycle, A,,, then is an index of the strain hardening capacity at a particular deflection level. A plot of n vs ? is reproduced in Fig. 3 for two ASTM steels: A-302 and A-201. A-302 is a low alloy structural steel, A-201 a low-carbon steel. The specimens were first normalized at 1650°F for 75 min then grooved with a milling cutter; and the notches were ground to 50G finish. The final operation before testing was a stress relief at 1150°F for 75 min. The behavior of the two steels changes around ?1 = 0.8 pct or A,, = A, -n = 0.7. If these curves are compared with the endurance life curves given in Fig. 4, it will be seen that the relative performance of the two steels also change around A,, =. 0.70 pct. The steel with lower strain hardening capacity (7) at a certain strain level shows a longer endurance life, irrespective of their strength levels. Since the exponent governs strain hardening at lower strain levels than the Modulus, the relative values of both parameters also coincide with the change in n values and the relative performances of the two steels at different strain levels. These two observations indicate to the close relationship be-

Jan 1, 1962

By E. A. Gulbransen, J. W. Hickman

DURING the past two decades considerable progress has been made in the art of manufacturing heater alloys. The conventional iron-chromium-nickel alloys have been improved by the addition of small quantities of other elements. Up to the present time, to our knowledge, there has not appeared a systematic study of these alloys where the newer tools of investigation have been brought to bear on the problem. It is not yet clear what roles the additional elements play in increasing life time in usage. As a first approximation one might guess that elements such as manganese, silicon, zirconium, calcium and aluminum would aid in the formation of a protective film on the alloy surface, thus retarding the oxidation rate and increasing lifetime. If these additional elements do form protective oxides in the outer surface of the oxide film, it may be possible to identify them by means of reflection electron diffraction. It is also possible that the additional elements may not diffuse to the surface but may remain at the interface between the oxide and the metal. Then, too, the major elements in the alloys undoubtedly form oxides which are stratified on the surface. If the minor elements concentrate in a layer in contact with the substrate where they undergo oxidation and if this oxide film offers resistance to the diffusion of iron, chromium and nickel ions, then the lifetime of the heater element might be expected to increase. It is also possible that preferential reduction in the diffusion rates of the several ions may Occur to such a degree that oxides may form in the body Of the film and On the outer surface which are different from those that would normally form if the additional elements were not present. The use Of transmisson electron diffraction may aid us in jnterpreting these phenomena. UP to the Present time all Of the factors which influence the lifetime of a given heater element are not definitely known. Among these are: (I) The rate of oxidation of the alloy. This may be dependent upon the composition and the physica1 state of the "alloy. (2) The stability of the structure of the coating which forms. Transitions from one structure to another or solid phase reactions resulting in a change of composition may occur. The tendency of the film to adhere to the substrate when heated and cooled successively will be important. (3) The evaporation of various constituents from the alloy such as the remova1 of carbon by Oxygen in a decar-burization reaction. With these possibilities in view, an electron diffraction study of the oxides occurring on six different nickel-chromium alloys was undertaken with the hope that the results of this study could be correlated with oxidation rate studies as determined by means of the vacuum microbalance method1 and with lifetime tests carried

Jan 1, 1949

By Chikao Nishiwaki

INTRODUCTION The Japanese dependency for mineral raw materials from foreign sources increased rapidly within the 20 years since the Korean war. During this 20 year period Japan has attempted to industrialize and develop her economy while depending mostly on heavy import of nearly all kinds of mineral raw materials. She has fabricated them using energy generated mostly by mineral fuel that are also imported. Fabricated goods are either used domestically to accelerate more fabrication industry or exported after adding more refinement or fabrication. In this paper iron ore as a major raw material for the Iron and Steel industry, three major base metals, copper, zinc and lead, and petroleum as a major energy source have been selected as examples to represent the general features of various kinds of mineral raw materials that are imported. Among other important mineral commodities for which Japan dependa upon foreign sources are: Aluminium, nickel and cobalt, potash and phosphorous 100 percent dependent and tin, tungusten, chromium and molybdenum over 95 percent dependent. IRON ORE Statistics for the important iron and steel raw materials, namely iron ore, coal and scrap iron are shown in Tables 1, 2 and Fig. 1. Iron ore is by far the most important and basic among these three commodities. There has been practically no steel or iron imported as a metal into Japan during this period. Iron ore, including aggregate such as pellets, and metallurgical coal are mostly transported in large ore cargo boats to the port where very efficient port facilities unload them directly at the steel mill site. As a result

Jan 1, 1976

By L. E. Young

IT has been said the British Empire was built on British Coal. In all the postwar planning for Great Britain the necessity for producing cheap coal and the prosperity of the coal industry are given first consideration. On Jan. 23, 1945, there was released in London a "Report to the Colliery Owners" which had been awaited with great interest. This was entitled "A Plan for Coal" and was the recommendation of Robert Foot, chairman of The Mining Association (Colliery Owners), prepared at their request. Presentation of the "Plan" at this time is particularly significant as it is an answer to the demand for nationalization of the coal industry by the Labour Party and at the same time is a carefully considered program for postwar reconstruction, prosperity, and stability. In the words of Mr. Foot, If the coal industry for the first ten years after this war is to find itself in a situation similar to the one it occupied for the ten years following the last war, with its record of disputes, strikes, stoppages, short-time working, unemployment, and, with it all, a completely insufficient margin of profit, and all the insecurity and instability in our basic industry that was brought with them, it is goodbye to any real prospect of full employment, social security, and high standard of living. To present an elaborate review of the conditions which have brought to a crisis the unfortunate situation in the British coal industry is here unnecessary, but certain of the salient points

Jan 1, 1945

By AIME AIME

Further details of the 97th meeting of the Institute, at Spokane, have been sent to members in the Special Circular of May 8, 1909, and for convenience a summary of the additional information is given later in this announcement. In spite of the present small number who have joined the party, final arrangements have been made to complete the itinerary given in the circular. It is greatly to be desired, both in behalf of the Institute and in recognition of the special courtesies to be extended on the trip, that the party be made larger. Exceptional facilities to visit the many mines and smelters have been freely provided; and members are requested to make all reasonable effort to attend the meeting at Spokane and participate in the excursions. . For those who cannot take the entire trip, it may be possible to provide special Pullman accommodations after leaving the Yellowstone Park. In order to make the necessary arrangements, however, the names of members and guests contemplating this partial trip should be sent at once to Mr. Theodore Dwight, .39 West 39th St., New York, N. Y. A special train of Pullman cars will leave Chicago September 16. This train will be side-tracked at all places visited, and the sleepers will be available for lodging and the dining-car for meals (luring the entire trip, except while taking the tour through the Yellowstone Park. The general cost of the trip per member will be $300, which includes transportation, berth, and meals for the entire trip from Chicago back to Chicago, almost 6,000 miles, and the tour through Yellowstone Park, occupying in all about 30 days. Special accommodations on the train will be furnished at the following rates

Aug 1, 1909

By AIME AIME

AT FOUR O'CLOCK members gathered in the auditorium for the annual business meeting of the Institute which, according to its charter, must be held on the third Tuesday of February each year. President Turner presided and after the usual formal action on minutes announced that he would create a precedent by transferring the President's annual address (which by tradition has always been delivered at the banquet on Wednesday evening) to the business meeting, and, furthermore, would only present a brief abstract of it. Since it appears in full on pages 127-131 of this issue it can be followed with the careful attention its thoughtful analysis of current conditions deserves.

Jan 1, 1933

By Elwin L. Fisk

The Cordero mine is located in the Nevada portion of the Opalite Mining district that straddles the Oregon-Nevada state boundary. The mercury deposits of the district occur along the margins of the broad east-west graben valley of McDermitt Creek. The only other major producers, the Opalite and Bretz mines, on the northern margin of the graben have thus far exploited only shallow deposits within 100 feet of the surface. Through December 1965, Cordero has produced 94,680 flasks of mercury, the most of which came from the large underground cinnabar deposit. Nearly all of the mercury ore deposits in this district have been found in Miocene rhyolitic intrusives, flows, tuffs, and lake beds. These rhyolites have been argillically altered at depth and extensively silicified at or near the surface. These silicified areas or "opalite" masses were the original cinnabar-bearing outcrops.

Jan 1, 1968

By C. D. Haynes, S. C. Gambrell

The practice of roof bolting in WORLD-WIDE mining activities is very well-known, having been used extensively for over 50 years. The theory of roof bolting, however, is extremely complicated, and only recently have investigators attempted to explain the theory. Various means of stress analysis have been utilized in rock mechanics, most of which reduce rock to an isotropic, homogeneous medium that can be easily analyzed. One of the indirect research methods is the photo-elastic technique, the theory of which is widely known and needs no elaboration. This technique has been used extensively to examine the state of stress around underground openings of various shapes in certain types of strata, and under various loading configurations.'-" In-Situ Mine Roof Trusses The photoelastic technique was employed here to evaluate the state of stress above a mine opening where support is provided by the in-situ mine roof truss. This support configuration, shown in Fig. 1, has gained popularity in recent years, particularly in mines with bad roof conditions." To the authors' knowledge, no scientific determination has been made of the advantages roof trusses may offer over conventional bolting configurations comparable to roof trusses. Ordinary mine roofs usually sag or bulge downward soon after mining. Normally, after some movement the roof begins to stabilize, but the face of this bulging mine rock is usually in tension and will almost always fail unless supported. Because rock fails easily in tension, it is desirable to "preload" the roof, that is, to impress a compressive force on the mine roof to prevent bulging and subsequent tensile failure. Ordinary rock bolting installations, particularly if the bolting is perpendicular to the mine roof plane, do not produce a preloading effect. Although bolting installations squeeze the strata together and produce a beam effect desirable for support, they do not have the advantage of actual uplift. They pull down at the anchorage point with a force equal to the bolt tension which sometimes causes a separation in the plane of the anchorage detrimental to roof strength. In-situ mine roof trusses require the installation of steel tension rods in the roof of the mine much the same as conventional roof bolts, except that the rods are arranged to produce a stress pattern above the upper surface of the opening similar to that of a prestressed beam. The roof rock acts to transmit the compression force. The simplest form of truss consists of two steel rods anchored to the back of holes drilled at an angle of approximately 45 over the mine pillars. These rods are collared near the middle of the room, and the lower ends of the rods are connected by tie rods and turn-buckles. Used in this manner, a small-diameter steel rod can provide essentially the same support as a wide-flange steel beam. By tightening the turnbuckles, an uplift on the roof can be produced. Objective of the Investigation The objective of this investigation was to determine qualitatively the state of stress that exists above a mine roof after the installation of the in-situ mine roof truss vs. that of two angle roof bolts, hereafter referred to as "roof bolts," drilled and placed in the same configuration, that is, 45" above each pillar and connected together in the middle of the room by a bearing member such as a steel beam. Each state of stress was to be identified, insofar as possible, as compression or tension above the mine opening. Model Construction A photoelastic model of a mine opening was coil-structed from -in. thick PLM-4B birefringent plastic and was machined to specification shown in Fig. 2. The dimensions of the opening were chosen to simulate a width-to-depth ratio of 3 to 1. Two % -in. holes were drilled at 45" angles, as shown, to provide for the loading devices. After construction, the model was annealed at 240°F to remove stresses produced during machining.

Jan 1, 1971

By C. H. Snyder

Tlie paper deals with details of construction of the Colmol, including improvements in design that will be incorporated in new models. These improvements are results of problems encountered and worked out in experimental operation with the unit. Also included is a descriptive plan of operating where roof and air conditions are of the worst. A summary of production results from the machine is presented. THE various units used in conventional mining are well-built. Generally the universal under -cutter, driven by approximately 50 hp, weighs approximately 25,000 lb, and is a very strong piece of machinery. The drilling machine is not as husky as an undercutter, generally is driven by approximately 15 hp, weighs about 9000 lb, but is a well-constructed, sturdy mechanism. The loader, usually 60 hp, weighs approximately 24,000 lb, and certainly is a strong, rugged unit. The working parts of all three of these sturdy conventional units have been made of tough steel alloys for some time. With the use of three machines having a combined horsepower of approximately 125, with a combined weight of approximately 60,000 lb, and with the possible inherent advantage of single purpose machines performing a single function, the use of considerable explosives has been required to complete the conventional mining cycle. It was therefore our thought, upon conception of the first Colmol,* a machine which was to do the work accomplished by the three conventional units plus explosives, that it must be a rugged mechanism. Now, after building several units, after going through many and varied experiments, and after the expense of some million-odd dollars, we find we have observed and learned nothing that contradicts our original thinking. A continuous miner, if it is to give satisfactory performance, must be a rugged piece of machinery. Ruggedness has been, and is constantly, in the minds of our engineers in designing the Colmol. Improvements where they have been required have been in the direction of more weight, more horse power, better alloys, bigger hydraulic pumps and motors; in short, always, toward more torque, greater strength, more ruggedness. Now not only the finest steel alloys are utilized but more than 100 Timken roller bearings are used. The following is some pertinent data on models being built and to be built: The low unit: Cutting height, 30 to 42 in. By changing the upper gear case the maximum cutting height can be increased to 61 in., giving a variable cutting height of from 30 to 61 in. Width of cut, 9 ft 6 in. Width of body, 75 in. over tracks. Height of body, 271/2 in. Overall length, 23 ft. Driven by three 50-hp motors or a total of 150 hp. Weight, 26 tons. The intermediate unit: Cutting height, 451/2 to 72 in. Width of cut, 9 ft 8 in. Width of body, 77 in. over tracks. Height of body, 43 in. Overall length, 26 ft. Driven by three 70-hp motors or a total of 210 hp. Weight, 35 tons.

Jan 1, 1951