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By Sam Rosenblum

The anomaly ratio is obtained by dividing the analyzed value of an element by the anomaly threshold value of the element. The sum of anomaly ratios for all anomaly elements in a sample may be compared with similar sums for other samples, so that samples having the greatest anomaly- ratio totals can be recognized easily. In partial or full suites of ore elements the we of anomaly ratios is more meaningful than use of analyzed value because the ratios quickly indicate how use of analyzed values because the ratios quickly indicate how anomalous some elements are, and call attention to samples and

Jan 1, 1982

By J. B. Sellers, G. R. Haworth, F. W. Brackebusch, P. G. Zambas

Results of large-scale mining experimentation carried on in Stage II of the Anvil Points Oil Shale Research Program, Rifle, Colo., are reported. After a new adit was excavated, over 500,000 tons of oil shale was extracted during a 13-month period by a modified room and pillar method. Experiments in drilling and blasting headings, benches, and crosscuts are reported. Roof-bolting procedures, loading and hauling, and ventilation design are discussed. Results of the extensive investigations carried out by the cooperative industry group and earlier work by the U.S. Bureau of Mines indicate that mining oil shale is technologically feasible.

Jan 1, 1973

By L. D. Jaffe, J. H. Hollomon

THE effect of tempering temperature and time upon the properties of quenched steel is clearly a subject of great practical importance, as well as of considerable theoretical interest. It would be very desirable to be able to predict the properties of a quenched steel when given any selected tempering cycle, with a minimum of experimental work upon that heat or even type of steel. Two problems are involved: one consists of relating the structure obtained to the physical properties, and will not be discussed here; the other, with which this paper deals, involves the relations of time, temperature and composition with the structure obtained on tempering. Indentation hardness is perhaps the most convenient quantitative measure of the tempered structure, or of what might be called the "degree of tempering." Undoubtedly, it is not an exact measure, and in some cases (as when temper-brittleness occurs) pieces of the same quenched and tempered steel may have widely differing properties at the same hardness. However, hardness has the advantage of being simple to determine and is certainly the most widely used indication of the degree of tempering. Moreover, for fully quenched steels that are not temper-brittle and do not contain retained austenite when quenched, it appears that, in general, if the hardness of the steel is the same, the tensile and impact properties will also be identical, whether a high or a low tempering temperature is used. The tempering charts available in the metallurgical literature usually give the hardness as a function of tempering temperature for only one tempering time. However, in practice, tempering times frequently vary, and a method of converting tempering curves for one time to tempering curves for some other time would be very valuable. It is also advantageous, in determining the tempering treatment necessary for a given part, not to have to temper samples at several temperatures for the time used for the commercial tempering operation. A more satisfactory procedure would be to employ times of the order of 10 to 30 min., rather than 5 or 10 hr., and if possible to use only one temperature. Furthermore, it is frequently desirable, for reasons such as temper-brittleness,* to obtain a given hardness with short times at relatively high temperatures, and it would be convenient to be able to compute without tests the time required to produce this hardness. Remarkably few quantitative studies of the hardness of quenched steel tempered over wide ranges of temperature and time

Jan 1, 1945

By W. A. Weimer

Australia, the land of the kangaroo, koala, and the platypus, is often referred to as "down under" by people of the Northern Hemisphere. It is a tropical land and has very little freezing and thawing; consequently the in-place rocks are near the surface, exposing some of the unaltered mineralization. This type of geology induces the prospector and miner to search for minerals which lie at his feet (or not far under them), and it is adapted to open cut surface mining. Some of the rules and regulations applicable to exploration and mining in Australia will be interesting and helpful towards understanding acquisitions and control of minerals. They are common and basic to the United Kingdom. Throughout Australia practically all minerals are the property of the Crown (government), and their exploration and exploitation are administered by the state Department of Mines. Surface owners, or land lessees, do not control the minerals. Their mining codes protect the prospector. If a prospector obtains a permit, "miner's right," it entitles him to search for minerals any place within the state, only holding him responsible for damages he may incur in his exploration. If he finds something of interest, he may then apply for an authority to prospect, which gives greater latitude and protection in his work to develop the find. However, he will be obligated to spend a minimum specified amount to exclusively hold an area. He will be required to furnish maps, analyses, and geological data to the Mines Department. Presuming that he has located something economically valuable for mining, he may then apply for a mining lease or be granted a franchise to produce a specific material. It will contain a quantity clause so that the area cannot be held indiscriminately without production of the mineral. The states have Bureaus of Mineral Resources, Geology, and Geophysics that keep constantly abreast of the search for minerals and often do much of the drilling and deep boring to promote geological study for the states.

Jan 1, 1969

By E. D. Slone, F. L. Dillard

When a new mine is in the planning stages, one of the most important decisions to be made is the selection of' face haulage equipment and the interrelated transportation system to the surface. Equally important is the method of transporting personnel supplies and repair parts from the surface to the working places. When Bell & Zoller management elected to open the new Zeigler mine in the No. 9 seam near Madisonville, Ky., last year, various transportation systems were considered. It was agreed early that a slope mine would be preferred to a shaft mine, and that belt conveyors would be more economical than a rail system.

Jan 1, 1970

By John E. Dowis

Ore distribution being what it is, many of today's mining companies are forced to develop foreign reserves to satisfy the demands of their customers. This necessity complicates the economic picture for a company, because management must look well be- yond grade and tonnage to determine the feasibility of developing a foreign orebody. Above all, the taxes on such a development must be assessed. The difference that taxes can make in mining profits will be illustrated here for three countries-Canada, Mexico and the United States. For purposes of comparison, identical orebodies will be assumed to occur in all three countries. Only the taxes on these properties will vary. Grade, tonnage, gross income, production costs and production rates will all be the same. The discussion will be limited to federal taxes, because state and provincial taxes are usually negligible by comparison. Assumptions relative to the orebody and the nature of the company undertaking the operation are as follows: (1) Copper is the only value to be recovered. (2) Sixty million tons of ore have been delineated. (3) Underground mining is required, and the production rate will be 3 million tpy. (4) The life of the property is 20 yr. (5) Operations in Mexico or Canada will be handled by a subsidiary of a U.S. parent company. (6) The subsidiary will offer stock.

Jan 1, 1970

At a meeting of the Board of Directors, held Jan. 21, 1916, the following resolution was adopted: Resolved, that this Board has learned with indignation and sorrow of the unprovoked and brutal murder of 18 American citizens on January 10, in the State of Chihuahua, Mexico, and laments especially the death of Messrs. C. R. Watson, C. A. Pringle, H. C. Hase, and W. J. Wallace, who were members of the American Institute of Mining Engineers. As these men and their companies were engaged, in the lawful prosecution of their work, we trust that nothing will be allowed to prevent or delay appropriate action by our Government concerning the outrage by which they lost their lives;

Jan 3, 1916

By E. S. Greiner

THE hot working of chromium was first reported by Hunter and Jones; who used small pellets of the material obtained by the reduction of chromium chloride with sodium. Later, the working of chromium at 600° to 1100°C was reported by Marden and Rich,2 and at 1250°C by Kroll3 The hot rolled material3 had a Brinell hardness of about 150 (62.5 kg, 2.5 mm ball, 1 min) and was brittle at room temperature. Except for that associated with hardness indentations, no plastic flow in chromium at room temperature has been reported to the author's knowledge. Studies described here have shown slip markings in chromium after deformation at room temperature.

Jan 1, 1951

US underground mine production of nonfuel minerals was 153 million tons of crude ore in 1971, according to a recent US Bureau of Mines report compiled by Dravo Corp. Underground capacity includes all nonfuel mineral commodities and is distributed into three general categories: (1) metallic ores; (2) nonmetallic ores; and (3) construction materials, such as clay, sandstone, and limestone. All three categories are produced by a combination of open-pit and underground methods. While US underground mining represents only 5.9% of total domestic capacity, it is significant in the types of products produced. Domestic supplies of potash, trona, A lead, zinc, sulfur, and fluorspar are almost exclusively recovered from underground mines, as well as a significant portion of the gold, silver, molybdenum, and salt supply.

Jan 7, 1975

FRANCIS T. OMENS, ? Watsontown, Pa. (written discussion§).-In the second paragraph, Dr. Thwing mentions the various stages through which clay ware. must pass but he does not analyze the third stage, oxidation, suffficiently. There are two elements to dispose of in a great many, of the shales that must he burned; these elements are carbon and sulfur. Dr. Thwing speaks' of the carbon, but intimates that it is safe to have a temperature of -800° C., which we find to be rather dangerous on a great tiffany shales. With. one shale that we handle, we cannot go above 535° C. until we have passed this particular stage. At 800° C. the sulfur will begin-to pass off and it is very necessary that plenty of air be ad-

Jan 11, 1919

By Walter Weeks

CONSIDERABLE difference of opinion seems to exist as to whether the rate of air flow when a fan is placed on a given duct should be determined by the use of static pressure or total pressure characteristics. A little study will show that both methods are correct. Assume that a fan is connected to a duct by an expansion piece as shown in Fig. 1, and that steady flow is established. Considering the atmospheric pressure as zero pressure, let the static head at the outlet of the fan be h and the velocity at this point be v1. The total head at the outlet is then h + v1/2g? The total head at this point must be equal to the total head at the end of the duct plus the losses that have occurred between the two points. Let f be the friction loss in the straight duct, s the shock loss in the dif- fuser, and V2 the velocity at the end of the duct. Then h+ v12/2g=v22/2g + f + s FIG. 1.-FAN ON DUCT. A curve showing the value of the left-hand side of the equation for different rates of flow is the total pressure characteristic of the fan, while a curve showing the value of the right-hand side is the total pressure characteristic of the duct. If these two curves are plotted on the same chart, the intersection indicates the rate of flow when steady flow is established.

Jan 1, 1930

By Freeman Bishop

Before Capitol Hill hearings, primary metal producers are often called "concentrated industries" because there are relatively few companies in each category and most of them are large corporations. Capitol Hill still looks on large companies as inherently wrong, but there are about as many arguments one way as the other. Encourage Imports? Now comes Assistant Attorney General for Antitrust Richard W. McLaren to say that imports of metals and other basic materials should be encouraged to create competition for the concentrated industries here at home. Cloakroom analysts are wondering how this ties in with President Nixon's cabinet task force studying the copper price structure. This is chaired by Dr. Hendrik Houthakker, a member of the White House Council of Economic Advisers who has also indicated that the use of imports to pull down prices may be one way to create less inflation.

Jan 1, 1970

By Andrew Allan

The Thompson Creek Coal & Coke Corp. operates three coal mines which presently supply the United States Steel Corp. with high grade, medium volatile coking coal at a rate of 1000 tpd. Mining is done at an elevation of 8000 ft, approximately 13 miles southwest of the small town of Carbondale, Colo. The coal is cleaned mechanically by heavy media and Deister tables, after which it is trans- ported to the railhead at Carbondale. GENERAL GEOLOGY The coal beds in this area lie in the Mesa Verde formation of Cretaceous age. Three beds are now being mined, with a fourth possibility pending further exploratory work. Formation of the Rocky Mountains tilted the sedimentary strata approximately 30º and created considerable faulting throughout. These faults, which range from a few inches to 35- ft displacement, constitute serious obstacles to mining.

Jan 4, 1966

In uranium metallurgy, the main purpose is to obtain a product containing 80-85% U308 (yellowcake) from ores whose average grade is a mere 0.21% U30& Essentially, the task of extraction and concentration involves dissolving the ore's U308 values, followed by purification and concentration of the uranium-rich solution (using such operations as filtration, clarification, and ion-exchange), and then selectively precipitating and isolating U308. Leaching is First Step In yellowcake production mills, the first chemical change occurs by leaching the ore with either sulfuric acid-as done by Anaconda and Kerr-McGee-or with an alkaline solution of, say, sodium carbonate, as done by United Nuclear-Homestake Partners. The choice of either acid or alkaline leaching is not an arbitrary one: it depends on the chemical and physical characteristics of a particular ore. That is, on the presence of clays, organic compounds (usually of carbonaceous origin), and soluble impurities, as well as on the ore's wetness and grindability.

Jan 8, 1974

By George F. Kunz, Henry S. Washington

The recently discovered occurrence of diamonds near Mur-freesboro, Pike county, Ark., was brought to our attention by Mr. Samuel W. Reyburn (Trustee for Messrs. C. S. Stifft, A. D. Cohn, August Zinsser, Jr., and himself, owners of the property), through whose courtesy we investigated the locality of the deposit. Prospecting with the diamond-drill is now in active progress; but mining operations on a large scale have not yet been ordered. Geology.—The geology as well as the petrography of this interesting locality has been well described by Messrs. J. C. Branner and R. N. Brackett,' but they did not class it as dia-mondiferous, although Branner suggested that it might be. Briefly summarized, the igneous rock in which the diamonds are found is a vitreous peridotite, forming a stock or volcanic neck, which has broken up through the Carboniferous and Cretaceous quartzites and sandstones. After an extensive period of erosion, during which an unknown portion of the neck and pre-

Jan 1, 1909

By H. Foster Bain

FROM time to time geologists and mining engineers, impressed by the heavy demands made on our mineral reserves' by modern industry, and particularly by the steadily mounting rate of production necessary to meet that demand, have issued warnings as to the danger of exhaustion. There can be no dispute as to the fact that mineral deposits are exhaustible. New mineral, is not created to replace that taken from the earth and when a crop of mineral is once harvested another cannot be grown in the same area. The evidence of exhaustion 'of particular oreshoots, deposits, or even of whole districts is familiar to all who have mined. If one were to judge solely from the abandoned mills and prospect holes he would rightly conclude that mining is but a short-lived industry. If one were, furthermore, to assemble the data as to known reserves of almost any of the commonly used minerals, and divide them by the annual tonnage mined, he would come to the same conclusion. If, again, one were to consider the most carefully made estimates of competent men seeking to measure the earth's reserves of minerals and plot against them a projection of the curve of past consumption, he would be justified in viewing the situation with alarm.

Jan 1, 1930

By Peter Haasen

INDIUM antimonide has the zincblende structure. A possible defect that does not disturb the indium tetrahedron surrounding any antimony atom in this lattice (or vice versa) is obtained when neighboring

Jan 1, 1958

By Russell G. Haworth

Three companies, United States Potash Company, Potash Company of America, and International Minerals and Chemical Corporation, are now operating potash mines and refineries in the Carlsbad, New Mexico, area. The three mines are located approximately twenty miles east of Carlsbad. The deposits have been found ideal for mechanized mining methods. This summary has been compiled from information made available by the three operating companies.

Jan 1, 1949

JAMES P.. MUNROE.-The present situation is vastly different from the situation at the, time the paper was written. We now know pretty well what our problem with the disabled soldier is: 50,000 disabled men have come back and the Surgeon General tells us that probably 35,000 more are coming over in the months of March and April. So the total number of disabled men will be 85,000, which of course includes a great number of slightly disabled. If we followed the proportion that obtains in other countries, we would have about 10 per cent. of those people to be retrained under the Vocational Law. As a matter of fact, the general intelligence of our men is so much higher and the provision the government has made for the training off these disabled men is so much more liberal than with the other governments that we feel very certain indeed that instead of having 8500, men to be retrained there will probably be twelve and possibly fifteen thousand.

Jan 4, 1919

By Hans Lundberg

BASED upon an instrumental improvement, a new development has taken place in the art of electrical prospecting, and some remarkable results have already been obtained with regard to potential exploration. In order to visualize the importance of this development, it is deemed advisable to review briefly the fundamental facts about potential surveys. Potential exploration may be carried out qualitatively or quantitatively. Qualitative investigations are made by determining and plotting on a map points of equal potential, whereby any anomalies are revealed, without, however, much clue to their magnitude. Quantitative investigations determine the variations of potential or potential drop, and thus show not only the location of the anomalies, but also their magnitude. Figs. 1 to 6 illustrate the influence of simple types of ground inhomo-geneities, assuming one effective exciter potential only. Such a condition can be closely realized by connecting an electric current source to two electrodes, one of which, is located at a great distance. Assuming uniform ground resistivity, the resultant potential distribution may be represented by concentric spheres. Any change from the normal condition causes a characteristic distortion of the spheres, which becomes different for different types of resistivity variation. The series of Figs. la to 6a illustrates schematically results of qualitative investigations and series 1b to 6b results of quantitative investigations. Figs. 1 and 2 picture the well-known case of local resistivity variations normally encountered in ore prospecting. Figs. 3 and 4 show the reactions caused by more or less vertical resistivity contacts and Figs. 5 and. 6 refer to the problem of ground-water and bedrock investigations where the resistivity contact is horizontal or nearly so. It is evident from Figs. 5a and 6a that qualitative measurements do not permit an identification of such general geological features as widespread horizontal strata, because the resultant contraction or expansion of the equipotential circles at the surface cannot be recognized without quantitative determinations. On the other hand, qualitative measurements are well suited for the exploration of local or lateral resistivity

Jan 1, 1931