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By R. W. Ballmer

Prior to initiating construction of a new mineral development project, sponsoring organizations must be convinced that the operation will be viable. Proof is typically provided by the feasibility study. Considerable man hours will be spent in assessing and evaluating data on the deposit, its environment, and the means of development. Impact studies must be made for various scales of operation, inclusion of by-products, new methods of treatment, deferent levels of integration, and infrastructure configuration. Examples of current materials handling cost estimates are provided from the ongoing investigation in which Amoco is a participant at Ok Tedi in Papua New Guinea and Gag Island in Indonesia.

Jan 1, 1979

"Mechanical alloying (MA) synthesizing technology and thennohydrogen processing (THP) were utilized to produce nanocrystalline Ti-MMC's reinforced by TiB intermetallic compound by using TiH2-B powder mixtures. Powders MA'ed up to 8 hours were examined by X-ray diffraction and SEM study. All MA'ed powders afterwards were HIP'ed at 700, 800 and 950EC for 1 hour. Detailed XRD, SEM and TEM study of the samples were carried out to determine the structure and micrography of the Ti-TiB MMC material processed by MA+THP approach followed by HIP'ing at high temperatures.IntroductionThe fiber reinforced titanium base composites [1,2] which possess a great resistance to high temperature have been investigated. In these studies fibers of C and SiC were used as reinforcing materials. However, these fibers react with Ti-matrix at elevated temperature resulting in product formation at the interface between the matrix and the fiber. Because of the chemical reactions, strength of the product MMC material diminishes.In conventional techniques of whisker reinforced composite material production, the mixtures of matrix metal powders and dispersed fibers are consolidated by hot pressing, HIP and/or hot extrusion. These techniques, however, have some shortcomings. Hard and brittle fibers could be broken during mixing cycle of the processing. Consolidation techniques could also be the cause for fiber breakdown. Attaining of the uniform dispersion of fibers into the metal matrix is not an easy process. The chemical reactions at elevated temperature exposures in the interface between the matrix material and fiber reinforcement cause product formations leading to poor mechanical properties."

Jan 1, 1998

By T. S. Lundy, R. A. Padgett

The fact that cobalt diffuses in silver at a much slower rate in a region near a free surface than in bulk material has been demonstrated in a variety of experiments. Various possible mechanisms of this near-surface effect (NSE) are examined in light of experimental evidences. The tendency for surface segregation of some solute atoms appears to be a likely mechanism to explain the effect. UNIDIRECTIONAL and isothermal diffusion from a plane source of radioactive tracer into an isotropic, homogeneous medium follows the Gaussian solution to Fick's second law, or: where A(x,t) is the position and time-dependent concentration of the diffusing species, M is the quantity of diffusant per unit area initially at x = 0, and D is the diffusion coefficient. For a given time, say t = tl, one can easily see that: d In Aixji)_____1_ r2] d(x2) 4Dti Thus, if diffusion data obtained by serial sectioning are plotted as In A(x,tl) vs x2, the diffusion coefficient is obtained from Eq. [2]. The ideal behavior seldom is observed in real systems. Deviations from ideality generally occur either at small or large values of penetration distance. The overall picture is shown schematically in Fig. 1 where Regions I, 11, and 111 are due, respectively, to some near-surface effect or effects (NSE), volume diffusion, and short-circuiting effects. For different systems and conditions of specimen preparation and analysis, the relative importance of Regions I, 11, and I11 may be drastically different. Region I is completely absent in many systems and there is no NSE. In others, however, there may be considerable difficulty in determination of volume diffusion coefficients due to the overshadowing influences of Region I. Such is particularly true when indirect techniques such as the surface concentration decrease or the Gruzin method' are used to find D. In this paper several experiments which had as their goal a better understanding of near-surface effects are reported. Specifically, it is well-known that unusual penetration behavior results for the diffusion of several impurities in ilver- and that considerable controversy exists with regard to interpretation of the published diffusion data. We chose to examine those unusual results which occur for cobalt diffusion in monocrystalline silver395 primarily because knowledge of experimental procedures and materials were readily available. Both radioactive co60 and co5' could be utilized to offer a wide range of available concentration of the diffusing species. Experiments were also performed on the diffusion of AgnO in silver. They gave base-line data for the system—both for technique evaluation and for examination of the vacancy distribution near the surface. I) PROCEDURES Cylindrical-shaped specimens 1.25 cm diam and 1 to 1.25 cm long were cut from 99.999 pct Ag single crystals obtained from Monocrystals Co., Cleveland. One end surface of each specimen was polished flat and etched with a mixture of 20 ml saturated Cr03 solu-tion-20 ml H20-3 ml concentrated HC1. Radioactive tracer (co60 or co5' or Ag'lO, each having a radio-chemical purity of greater than 99 pct) was deposited onto the prepared surface either dropwise with evaporation to dryness of the solution containing the tracer (0.5 N HC1 solution for the co60 and co5' and 0.6 N HNO3 solution for the A"'), by electroplating, or by evaporation from a tantalum or tungsten filament in an evacuated bell jar. The amount of deposited cobalt was varied from many atomic layers of cobalt containing the co60 to approximately one co5' atom per lo6 surface atoms of silver. This large variation in amount of deposited cobalt yielded information about both the influence of a thick-source layer of tracer and solubility effects on the NSE. Such variations were possible because of the large differences in half-lives,

Jan 1, 1969

By R. Stefanko

The industrial hygiene and safety aspects with internal combustion engine in mining systems is truly interdisciplinary and encompasses many fields such as mine ventilation, exhaust gas and particulate analyses, mine atmospheric environment monitoring, mathematical modeling of generation, dilution and dispersion of pollutants in ventilation systems, and engine testing and approval. Mathematical models of the dilution and dispersion of diesel exhaust contaminants can be useful only if these models can be validated. In this research report, experiments that were specially designed for the above purpose are described. These experiments were conducted in the U.S. Bureau of Mines, Safety Research Coal Mine, in Bruceton, Pa. On the basis of this study, the data collected, and further review of available literature, it is concluded that mathematical models of dilution and dispersion are useful tools for mine ventilation planning. Additional objectives of this study about which conclusions and recommendations are reported here include: (a) evaluation of mine atmosphere contaminant monitoring systems; (b) optimum sampling site locations; (c) model sensitivity and error analyses; (d) computer coding of mathematical models; and (e) development of a diesel bibliography. While an extensive bibliography on diesels is provided in this report, Volume II of this final report has 511 references.

Jan 1, 1977

This paper reviews the development and operation of a small underground tin mine in NE Tasmania. Tin mineralisation was discovered in the Lottah area in the 1880's with early alluvial and eluvial workings leading to the development of large low grade open pit operations. Apart from short lived activities operations ceased in 1915. Intensive exploration in 1978-81 outlined substantial tonnages of low grade tin mineralisation (0.2% Sn) of open pit material. An underground ore body was also located (800 000 tonnes 0.6% Sn). Spectrum Resources Australia Pty Limited acquired a 98 percent interest in the property in 1988. Mine and mill development began in early 1989 based on an underground mine utilising trackless mining using room and pillar with fill stoping. The milling circuit involves primary jaw crushing, Barmac secondary crushing to lmm, Mogensen and DSM screens with jigs and tables to make a wet concentrate. Final tin concentrates are produced by high tension and magnetic separation. Planned production rates are 500 t/day with a mine life of 6-7 years.

Jan 1, 1990

By Ali Kazmi, Wern-ping N. Chen

A load rating procedure was performed to evaluate safe load capacity of the Port of Miami Tunnel (POMT), FDOT Tunnel No. 871071 SR 887. The rating procedure performed on a total of eleven stations beneath roadways and with fill depth less than the tunnel exterior diameter (42 ft). Calculations on tunnel sections passing beneath roadways were performed to evaluate the structural response of the sections subject to moving vehicular loads, dead load, and earth pressures. Ratings were performed in accordance with AASHTO and FDOT guidelines. The procedure considered two types of vehicles (HL-93 and FL-120) and two rating levels (Design level and Permit level). As part of HL-93 vehicle, Tandem load was also considered for rating, separately. For HL-93 and HL-93 Tandem, inventory and operating level ratings were performed. The results show rating factors are high. The minimum rating factor is 16.8 using Inventory truck HL-93. For Permit level using FDOT FL-120 truck the minimum rating factor is 6.9. As can be seen, rating factors are higher than comparable analysis for bridges. This paper explains how the procedure can be implemented for tunnels and evaluates the rating results.

Dec 1, 2022

By John J. Dran

[This paper summarizes the more popular mineral valuation techniques being used by the dining industry, and attempts to demonstrate how they are Interrelated and where some are in error when compared to modern methods of financial analysis. The academic community and the larger and more sophisticated raining companies, have largely rejected the older valuation methods such as the, Hoskold and Morkill concepts and replaced them with "discounted cash flow" (DCF) techniques. The relevancy and usefulness of the older methods have been questioned primarily on the basis of their underlying assumptions that mining companies do not have numerous alternative investments and must use sinking funds deposited at market or ?safe" rates of return to recover the purchase price of mineral reserves. The ability to reinvest In numerous (often non-mining} alternative business ventures, the changing purchasing power of the dollar, corporate income and other taxes, depreciation and depletion allowances, and modern financial management practice, all mitigate against the continued use of the older valuation methods, especially for the larger mining companies. Snail mining companies and Individuals still use these methods largely out of habit and familiarity. This paper attempts to point out the weaknesses and strengths of the valuation methods In current use in the hope that these techniques may be better understood and [rcrn] appropriately applied.]

Jan 1, 1973

By Jr. Herty

Ferromanganese continues to be an indispensable requirement in steel manufacture. Approximately 470,000 of the 80 per cent ferro-alloy was consumed in 1929 and increasing amounts will be required annually by the steel industry unless some satisfactory substitute is found. An average of 14 pounds of metallic manganese is used for each ton of steel produced, The principal use of manganese is for de-oxidation of the metal in the steel refining processes, although a considerable amount is also used for the production of special manganese steels. Unfortunately, domestic production of manganese ore is inadequate to meet normal peace-time requirements, not to mention increased abnormal war-time demands. The rather large quantities of low-grade manganiferous iron ores which occur in the Coruna Range in Minnesota have for a number of years greatly appealed to those interested in the development of a domestic source of the supply. The North Central Experiment station of the Bureau of Mines has made an elaborate study of the possibilities of the pyrometallurgical treatment of ores from these deposits and much of the valuable information secured by them has already been published.

Jan 1, 1930

By C. H. Herty

[Ferromanganese continues to be in indispensable requirement in steel manufacture. Approximately 470,000 tons of the 80 per cent ferro-alloy was consumed in 1929 and increasing amounts will be required annually by the steel industry unless some satisfactory substitute is found. An average of 14 pounds of metallic manganese is for each ton or steel produced, The principal use of manganese is for deoxidation of the metal in the steel refining processes, although a considerable amount r s also used for the production of special manganese steels. Unfortunately, domestic production of manganese ore is inadequate to meet normal peace-time requirements, not to mention increased abnormal war-time demands.]

Jan 1, 1930

By John W. Kopp

Stemming is used in blasting operations to help contain explosive gases as long as possible. Stemming can reduce airblast, improve fragmentation, and reduce the chances of hot explosive gases igniting methane and dust explosions in underground mines. Stemming is required in underground coal mines but is generally not used in underground metal and nonmetal mines. Some underground metal and nonmetal mines are classified as gassy and can require special blasting procedures such as the use of stemming to minsure the safety of miners. The types and amounts of stemming material that are desirable in underground metal and nonmetal mine blasting to ensure good or improved fragmentation while containing the hot gases are largely unknown. This Bureau of Mines research examined the effectiveness of differing lengths of stemming by measuring stemming ejection times as related to burden movement. With properly stemmed blasts, stemming is contained until some burden movement has occurred. Test blasts at two surface limestone quarries were evaluated using high-speed photography. For the conditions of these tests, a stemming length of at least 26 charge diameters was found to prevent premature stemming ejection. In tests with stemming lengths of 16 charge diameters, the stemming was effective but there was early venting of hot gases through fractures in the rock. Further testing with other rock types, hole diameters, explosive types, and stemming materials as they affect incendivity is recommended.

Jan 1, 1987

By Richard E. Chism

Some years ago, when I was seeking an illusive fortune and gaining a precarious existence in the primeval forests of Brazil, there penetrated, even to my headquarters in that far-off land, the story of a new-found mining district, where mountain peaks were ribbed with silver, and valleys teemed with virgin gold. Such were the stories that caused hundreds of men to seek their fortune in Sierra Mojada, and to return heaping curses, loud and deep, upon the vivid imaginations that had evolved the glittering fiction. Nevertheless, the rumors had some foundation of truth. The ribs of silver exist, if not the placers of gold; and a flourishing town, of some three thousand people, with two leading mining companies and several smaller ones, in operation, represents what was permanent in the excitement of 1879. Geographical Situation. The town of Sierra Mojada is situated in the State of Coahuila, Republic of Mexico, in latitude 27' 24' N., and longitude 26' 40' W. of Washington, 4' 36' W. of the City of Mexico, and 103' 43' TV. of Greenwich. It lies about 70 miles, in an air-line, N. E. of Escalon station, on the Mexican Central Railroad; but by the present wagon-road, which makes a long detour to turn the mountain range, the distance to the station is about 105 miles. The nearest towns are Huajuquilla, in the State of Chihuahua, about 125 miles due west, and Cuatro Cienegas, in the State of Coahuila, 112 miles to the eastward. Between these points and the town of Sierra Mojada, and to the north of this town, the country is an immense desert, entirely uncultivated, almost uninhabited, and very little known. This

Jan 1, 1887

L50 Adirondack L1 Alaska L2 Arizona L58 Arkansas L66 Billings Petroleum L3 Black Hills L4 Boston L5 Carlsbad Potash L6 Central Appalachian L60 Central New Mexico L7 Chicago L8 Cleveland L9 Colorado L57 Colorado Plateau L10 Columbia LII Connecticut L55 Dallas L12 Delta L65 Denver Petroleum L13 Detroit L14 East Texas L15 El Paso Metals L71 Evangeline L45 Florida L54 Fort Worth L16 Gulf Coast L61 Hobbs L62 Hugoton L68 Illinois Pet Basin L17 Kansas L18 Lehigh Valley L52 Lou-Ark L47 Mexico L19 Mid-Continent L20 Minnesota L56 Mississippi L21 Montana L22 Nevada L64 Niagara Frontier L23 New York L67 New York Petroleum L25 North Pacific L24 North Texas L26 Ohio Valley L27 Oklahoma City L28 Oregon L63 Panhandle L29 Penn -Anthracite L30 Permian Basin L51 Peru L31 Philadelphia L32 Pittsburgh L33 St Louis L34 San Francisco L59 San Joaquin L35 Southeast L36 Southern Calif L69 Southern Calif Pet L53 South Plains L37 Southwest Texas L48 Southwest Alaska L38 Southwest N Mex L44 Spindletop L39 Tri-State L40 Upper Peninsula L41 Utah L70 Venezuela L42 Washington, D C L43 Wyoming L49 West Central Texas L46 Philippine

Jan 1, 1956

By I. M. Gordon, J. Blackshaw

"Run-of-mine ore is reduced to 4 per cent on 4 mesh (3/ 16 inch), using four stages of dry crushing. The mill feed is then reduced to 2 per cent on 48 mesh and 60 per cent through 200 mesh, using one stage of ball milling in cyanide solution. During the subsequent treatment about one-tenth of the tonnage is removed as a table concentrate and ground to 77 per cent through 325 mesh. The size of the mill tailing is 66 per cent through 200 mesh.Four stages of ore reduction began when the dry crushing plant at No. 26 Shaft came into operation at a maximum rate of 440 tons an hour on July 31, 1941. A detailed description of the crushing plant was published in C .I .M. Trans., Vol. LVI, 1953.One-stage ball milling in cyanide solution came into full operation on January 11, 1938. The ball milling plant had a capacity of 4800 tons daily when reducing mill feed at 2. 7 per cent on 1/ 4 inch to 54. 3 per cent through 200 mesh. Primary grinding to 60 per cent through 200 mesh commenced May 22, 1945, when the feed was 3 per cent on 4 mesh. Under these conditions the capacity of the ball milling plant is estimated at 4300 tons daily. A description of the 11 Hollinger Crushing and Grinding Plant"" by D. C. McLaren was published in the Canadian Mining Journal, June 1944.The concentrate grinding circuit using a 7 x 15 low discharge ball mill and a 19-foot diameter bowl classifier with a 6-inch centrifugal pump to close the circuit began operating in the ball milling plant on October 24, 1939."

Jan 1, 1965

By E. J. Marcotte

"BRIEF DESCRIPTION OF GRINDING CIRCUITCrushed ore at -5/ 16 in. is delivered by a conveyor system from the crushing plant to two 1250 ton fine ore bins. The ore is transferred from each bin by a 30 in. feeder conveyor belt, operated by a Link Belt P.I. V. (variable speed) drive, to a 24 in. conveyor that feeds the 8 x 10 Allis Chalmers rod mill.The rod mill discharges to a common mill discharge pump box. Three 6 x 6 SRL pumps are employed to pump the combined mill discharge pulp to a common distributor box which distributes the feed to two of the three Kreb D lSB cyclones in each of the two banks at a hydraulic pressure of 6 psi.The cyclone overflow at a specific gravity of 1. 25 (i.e. 32% solids) is transferred by gravity to two revolving chip screens for wood chip removal and from there to a pump box. Two 5 x 5 SRL pumps feed the pulp to the thickeners. The underflow from the cyclones is fed to two 8 x 8 Allis Chalmers ball mills which discharge to the common mill discharge pump box. Thus, a closed circuit is formed between the ball mills and their respective bank of cyclones. The circulating load as most recently calculated is 262%."

Jan 1, 1966

By John Dasher

Extrapolation is a useful technique, but it can be overdone. Seldom is it justified to study over a range of 1 to 6 and extrapolate the results to 150,000. It is especially dangerous if the extrapolation is based on a false assumption. The authors assume settlers scale-up by residence time rather than by area, admit their result (a settler depth of 7 m) is "unreasonable" and suggest longer, wider, shallower settlers might be better. Various authors have noted for a copper-LIX system a total flow basis of 2 gpm per sq ft for sizing settlers. The results of this are compared with those in the paper in [Table 7]. The authors note that flooding of their settlers was never approached. Thus the smallest unit calculated is understandably twice too big. The largest however, is 5% of the required size. I note that the figures in [Table 6] for 1/min/cm2 are based on plan area rather than cross section as titled and are wrong by l0 4. A flow of 2050 1/min/cm2 is about Mach I. It is also 10 5/3 or 46.5 times that of the little one, although the abstract says the design was based on constant flow rate per unit cross section.

Jan 1, 1977

By W. P. Sykes

In connection with a study of tungsten steels, Honda and Murakamil reported an investigation of the system iron-tungsten. This report included a tentative equilibrium diagram, photomicrographs of various alloys in the series, and qualitative measurements of hardness and magnetic properties. The present investigation originally had as its object the study of the hardness and tensile properties of a series of carbon-free iron-tungsten alloys. But, as the work progressed it became evident that the system possessed other features of interest, so the scope of the investigation was enlarged. Materials The iron powder used in preparing the alloys was obtained as follows : Iron oxalate was precipitated from a ferrous-sulfate solution by the addition of a solution of oxalic acid. This oxalate, after thorough washing, was ignited to iron oxide, which after reduction in hydrogen at about 1000" C. yielded iron powder containing but about 0.2 per cent. iron oxide and about 0.005 per cent. carbon. Tungsten metal in the form of powder, such as is used in the manufacture of filaments for incandescent lamps, was the other constituent. This material analyzed 99.8 per cent. tungsten and contained no carbon. The metal powders, in the desired proportions, were mixed by tumbling and formed, under pressure of 20 tons per sq. in., into rods 3/8 by 3/8 by 10 in. To form the alloys without contamination, sections of the pressed rods were placed on alundum slabs and heated in an alundum tube wound with a tungsten resistor and packed in heat-insulating material. While the resistor was heated, a stream of hydrogen was continually passed through both the tube and the case containing it. The tungsten winding on the tube, as well as the material heated within the tube, was thus protected from oxidation. Such a furnace will operate constantly for several days at temperatures up to 1500' C. and for shorter periods

Jan 1, 1926

By John C. Branner

Five of the geologic horizons that yield oil in other parts of the world are represented in Brazil; namely, the Devonian, Carboniferous, Permian, Cretaceous, and Tertiary. Thus far, the first two have shown no evidences of being oil bearing within Brazilian territory. Not enough exploring has been done to permit trustworthy comparisons of the relative importance of the Permian, Cretaceous, and Tertiary as oil-bearing horizons in this country. The most important, indeed almost the only, information available relates to the locations of the areas and to the structural features of the several horizons. The theories regarding the physical conditions under which these rocks were laid down, however, I regard of the utmost importance. Permian Rocks of Permian age cover an enormous area in Brazil, extending from Rio Grande do Sul to Maranhao on the north, and to Matto Grosso on the west. These Permian rocks in many places are known to include oil-bearing shales and in some locations contain small veins of gilsonite. The geologic map of Brazil shows that the Permian area is widely distributed, but there is considerable doubt about the origin of some of the rocks. Some of the lower Permian beds in southern Brazil contain marine fossils, but in Minas no fossils have as yet been found in them, and in Bahia, at only one locality have a few Permian plants been found. Indications of oil have been found in the states of Sa0 Paulo, Parana, and elsewhere farther south, but wells drilled in the Permian of SaO Paulo near the Morro do Bofete did not find oil. One well has been started, by the Brazilian Government, in the Permian of Parana near Marechal Mallet, close to latitude 26" south, but thus far oil has not been found.

Jan 1, 1923

By John C. Branner

Five of the geologic horizons that yield oil in other parts of the world are represented in Brazil; namely, the Devonian, Carboniferous, Permian, Cretaceous, and Tertiary. Thus far, the first two have shown no evidences of being oil bearing within Brazilian territory. Not enough exploring has been done to permit trustworthy comparisons of the relative importance of the Permian, Cretaceous, and Tertiary as oil-bearing horizons in this country. The most important, indeed almost the only, information available relates to the locations of the areas and to the structural features of the several horizons. The theories regarding the physical conditions under which these rocks were laid down, however, I regard of the utmost importance. Permian Rocks of Permian age cover an enormous area in Brazil, extending from Rio Grande do Sul to Maranhao on the north, and to Matto Grosso on the west. These Permian rocks in many places are known to include oil-bearing shales and in some locations contain small veins of gilsonite. The geologic map of Brazil shows that the Permian area is widely distributed, but there is considerable doubt about the origin of some of the rocks. Some of the lower Permian beds in southern Brazil contain marine fossils, but in Minas no fossils have as yet been found in them, and in Bahia, at only one locality have a few Permian plants been found. Indications of oil have been found in the states of Sa0 Paulo, Parana, and elsewhere farther south, but wells drilled in the Permian of SaO Paulo near the Morro do Bofete did not find oil. One well has been started, by the Brazilian Government, in the Permian of Parana near Marechal Mallet, close to latitude 26" south, but thus far oil has not been found.

Jan 1, 1923

By H. E. Elliott, R. S. Busk, A. T. Peters

ONE of the problems of the fabricator of metals and alloys is the propensity of some composition ranges toward abnormal grain growth during certain stages of fabrication. In this respect magnesium alloys are no exception among alloys. Fortunately, convenient foundry control methods have been developed by which the abnormal grain growth possible in certain magnesium-alloy castings can be suppressed. An unusual characteristic of magnesium alloys, however, is that castings of some composition ranges are subject to local grain growth during heat-treatment without the necessity of intentional mechanical stressing of the part prior to heat-treatment. This effect occurs only under certain critical casting conditions, and only in certain alloys of greater than about 8.5 per cent aluminum content, such as C alloy (Mg, o per cent Al, 2 per cent Zn, 0.2 per cent Mn) and G alloy (Mg, i0 per cent Al, 0.2 per cent Mn). The first observation of this phenomenon in cast magnesium alloys occasioned much surprise, since it is not observed in other metals. Jeffries and Archer' have stated that "the grain size of cast metals, provided they have not been plastically deformed, cannot be changed by heating below the melting point." The study of the conditions leading to abnormal grain growth in cast magnesium alloys, and of the mechanism of this phenomenon, has led to some very interesting observations. Perhaps the most significant of these was the observation that stresses originating from cooling contraction in magnesium-alloy castings are the only stresses necessary, under certain conditions, to cause local recrystallization and subsequent grain growth in the casting during heat-treatment. of abnormal local grain growth was a definite problem in the production foundry on C alloy sand castings. Illustrated (Fig. r) is a picture of a casting scrapped because of this defect. A mottled effect is produced in coarse-grained areas by suitable etching solutions. The properties of metal in the affected area are much impaired by such grain coarsening. Ultimate tensile strengths of half the normal value have been measured in metal of this nature. In this paper are described the techniques that have been developed by The Dow Chemical Co. for studying, and in large measure solving, this production problem. Also discussed are studies of the mechanism by which excessive grain coarsening occurs, and the fundamental conditions that produce this effect. The abnormal grain growth discussed in this paper will be referred to as "germination," since this term has been defined' as any process leading to an abnormally coarse grain size. This paper deals only with abnormal local grain growth that may occur during the solution heat-treatment of certain magnesium-alloy castings, as dis-

Jan 1, 1945

By BUREAU OF MINES

This report is submitted in accordance with provisions of the Synthetic Liquid Fuels Act of April 5, 1944 (30 U. S. C. 321-325, as amended), which require that: "The Secretary of the Interior shall render to Congress on or before the first day of January of each year a report on all operations under this Act." Owing to the broad scope of the content and the diversity of interests represented, the Annual Report for 1954 has been divided into two separate publications. Each is being published by the Bureau of Mines as a Report of Investigations, and the respective titles follow: R. I. 5118, Part I - R. I. 5119, Part II - 011 From Coal. 011 From 011 Shale. The introduction, identical in both reports, summarizes research progress in 1954 under the entire Synthetic Liquid Fuels program. A free copy of either publication may be obtained by writing to the Bureau of Mines, Publications Distribution Sec- tion, 4800 Forbes Street, Pittsburgh 13, Pa. The R. I. number and title of the publication desired should be indicated.

Mar 1, 1955