Search Documents

By W. C. Ashby, C. A. Kolar

Extensive reclamation experience in the midwest dates from the 1930s with trees, from the 1950s with pastures, and from the 1970s with row crops. Superior growth and productivity of mined land over unmined land can be shown for forest and pasture, related to type of rooting medium after mining and kinds of plants gown. Superior reclamation to crops is actively being studied. Recent regulations have greatly altered the potential for superior growth of trees, pastures, and crops.

Jan 1, 1984

By D. A. Singer

A procedure whereby the completeness of search is calculated by using the area of influence of exploratory drill holes or samples is extended to allow for errors of recognition. The size, shape, and orientation of potential targets are mapped in a probabilistic sense on the array of drill holes or samples. The method can be used either to determine how well explored are the subregions within a previously drilled or sampled area, or to test proposed alternative search strategies. Examples of the use of the method demonstrate the complexity of sequential search when the areas of influence of drill holes or samples overlap.

Jan 1, 1976

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Jan 1, 1938

By Richard C. Timberlake

The disposal of phosphatic clays has presented a problem to the phosphate industry since the mining of phosphate rock first began in Polk County. As the flotation process was introduced in the late 1920's the problem of clay disposal was increased significantly since clay is present in proportionally greater quantities in reserves yielding flotation concentrates. Because of their physical character and the tremendous surface area per unit volume, these clays have the characteristic of retaining large volumes of water as they are slurried during processing. The disposal of clay and the recovery of a portion of the water require settling areas with a capacity ranging up to 2 cu ft for each cubic foot of phosphate matrix mined. According to a recent study by the Bureau of Mines, the average cost for disposal of these wastes is 24.5[c] per ton of product. This is a major cost of phosphate rock production.

Jan 12, 1969

By Clifton W. Livingston

So many factors influence blasting results that theories and rules are usually dismissed as impractical; the practice prevailing today is arrived at by cut and try. Usually the first step is to experiment with drillhole patterns and spacing until an arrangement is found that gives best results. The next step is to experiment with different types of explosives and sequences of blasting until the most satisfactory degree of fragmentation is achieved and until no further reduction in cost is immediately apparent. Improved fragmentation is generally attributed to the type of powder used, the sequence in which the holes are blasted, or the use of millisecond delays. Various types of drill rounds have been evolved in tunneling operations, underground development headings, and stoping, and various patterns of blasting in open pit mines and quarries. These practices usually are carried from mine to mine or from district to district, and great skill is exercised by those experienced in the art of blasting.

Jan 1, 1960

By R. A. Wood, R. I. Jaffee, H. R. Ogden, D. N. Williams

Dispersion-containing titanium-copper alloys were prepared having mean free paths varying from 1.0 to 9.7 P. Tensile studies at room temperature and at 1000°F showed that little or no strengthening occurred when the mean free path exceeded 3 p. However, at lower values of mean free path appreczable strengthening was observed. A considerable amount of strengthening also resulted from copper in solid solution. DURING the past several years, an increasing amount of study has been devoted to dispersion hardening, an alloying process in which increased strength is obtained through the addition of a ran-

Jan 1, 1961

By R. B. Strathmore Cooke, Eugene L. Talbot

The perfluoro acids and derivatives show unusual surface-active properties that qualify them as possible flotation reagents. They lower the surface tension of water from 15 to 20 dynes below that obtainable with the corresponding hydrocarbon compounds. Fluorochemicals adsorb very strongly on solid surfaces to give films that exhibit larger contact angles than films of the corresponding hydro-carbons. The large contact angles probably result from the terminal –CF3 group. The perfluoro acids are made by electrolysis of the corresponding carboxylic acid in anhydrous hydrogen fluoride. From the perfluoro acids many derivatives may be obtained, such as amides, amines, alcohols, xanthates, ethers and esters and others.

Nov 1, 1955

By J. F. Labuz

Fracture tests were conducted on subsize specimens of Charcoal granite to demonstrate that the extent of the nonlinear region at the crack tip can be significant. The model of the fracture process considers an effective crack length as a traction free portion plus a process zone where closing stresses act; this zone is identified by microcracking and interlocking. A singularity is allowed at the effective crack tip. The effective stress intensity factor is the superposition of the stress intensities due to the effective crack and the process zone. By assuming that the closing stress is a linear function, it is shown that a process zone length of approximately one-third the effective crack is needed to match the compliance-determined crack length.

Jan 1, 1984

By Thomas F. Evans

This study shows that statistics on the rate of coal dumping can measure the effectiveness of freeze conditioning agents. The use of appropriately indexed dumping intervals or interval logrithms provides a more sensitive indication of unloading problems than does a simple calculation of average loading time because of the abnormal form of the distribution of dumping intervals. The paper presents information that indicates suitably applied coal freeze conditioning agents are effective in reducing coal handling problems attributable to frozen coal. Graphs and figures show that the severity of coal freezing potential due to subfreezing temperatures is proportional to the exposure time and average departure of the temperature from the freezing point.

Jan 1, 1982

By Michael K. O’Leary, William D. Coplin

Risks from political instability and government policies restricting equity ownership, local operations and transfers of payments affect the profitability of foreign mining ventures. More than seat-of-the-pants judgments and old-boy networks are required to anticipate these risks and to take actions appropriate to offsetting them. A system for making political forecasts, called the Prince System, and a series of charts relaying risks to a production of key minerals has been developed.

Jan 1, 1985

POSITIONS VACANT Engineer to take charge of construction of smelter and mill. Experience with blast furnaces, roasters, belt-conveying systems and general machinery, essential. Salary $250 per month up according to experience. No. 129. Mine Engineer.-Man with experience, ability and initiative wanted to handle an organization, direct sampling, surveying, mapping and record keeping.. Experience in laying out development work, haulage-ways, shaft pockets and ore-handling systems, particularly desired. No. 130. Recent technical graduate for experimental work with a metal refining company. Laboratory work first to acquaint worker with methods, then research work. Good opportunity for advancement. Beginning salary $100 a month. No. 132. Mine superintendent. Man of experience and energy wanted in mine being developed to produce 5,000 tons of iron-ore per day from open-cut and underground. About to start underground operations. Expect to follow methods of low-grade copper mines of Southwest. No. 133.

Jan 9, 1916

By Robert H. Weber

Increasing acceptance of perlite products, chiefly in the fields of lightweight structural aggregates and thermal and acoustic insulation, has led to expanding market demands that have encouraged many new producers to enter the field. In some instances, however, the failure of these producers to anticipate the variable response of perlite to conventional processing methods has led to difficulty in establishing an economical flowsheet by which a predictable specification product could be obtained. It is not the writer's intent to provide a solution to these problems, but rather to summarize their nature. It is to be hoped that members of the industry who have hurdled some of these obstacles will document solutions arising from their experience.

Jan 2, 1955

By R. E. Zimmerman, Shiou-Chuan Sun

An evaluation of the mechanism surrounding the froth flotation of coarse coal and mineral particles as a result of experiments conducted at The Pennsylvania State College. Maximum size ranges for both bituminous and anthracite coals were established as well as the factors affecting the floating of coarse particles.

Jan 5, 1950

By J. Winter, W. C. Setzer, A. J. Goldman

ANISOTROPY in cold worked tempers of commercial aluminum alloys is manifested in deep drawn products as protuberances or ears 45 deg to the rolling direction. This reflects the {123}(412) rolling texture.' In fully annealed material, 0 to 90 deg ears in and per-

Jan 1, 1970

By I. Iwasaki, K. A. Smith

A chlorination process for treating metal sulfide flotation concentrates is described. The process involves low temperature chlorination combined with sulfur chloride conversion and selective oxidation to produce nonferrous metal chlorides, elemental sulfur, and ferric oxide in a three-stage fluidized bed reactor. The nonferrous metal chlorides may then be water leached, separated, purified, and electrolyzed to recover copper and nickel metals and to regenerate chlorine for recycling.

Jan 1, 1986

By J. E. Schaffer

Drilling activity in Ohio increased slightly in 1939. There were 1020 completions as compared to 910 in 1938. During the past six years the number of completions has varied little (Table 1). Oil production in Ohio has been gradually declining since 1896, when the peak production of 23,941,000 bbl. was reached (Fig. 1). Since that date production has slowly declined to an estimated production in 1939 of 3,144,134 bbl., the lowest in 53 years. This total production is divided approximately into the following grades of crude oil: Pennsylvania, 1,185,456 bbl.; Corning, 1,261,615 Flg 1. bbl.; Lima, 578,500 bbl.; Lodi, Based on figures of U. S. .Bureau of 104,740 bbl.; Cleveland, 13,823 Mines and Oil andGas Journal bbl. Table 2 shows the prices paid for the various grades of crude oil.

Jan 1, 1940

By Robert J. Alberts

Our shop started up in April of 1969, and during its 8th month of operation produced over 300,000 tons. Production continued to increase, and by January of 1970 tonnage rates significantly above 300,000 tons per month were being realized. Ours is a three vessel shop, producing 200 ton heats, with a normal grade breakdown indicating more than one half semi-killed carbon steel, with the balance distributed over rimmed and capped steel, alloy steel, killed carbon, and special killed drawing quality steel. The recent christening of a continuous billet caster has dictated that close to a quarter of our liquid steel be delivered to the caster.

Jan 1, 1972

By Allen L. Hatch

Perhaps the greatest challenge to the non-ferrous extractive industry, aside from discovery and cost reduction, is the continuous effort toward the total recovery of metals. This is-and must continue to be-a joint endeavor on the part of the miner and the smelter, the first to trend constantly toward that form of concentration most amenable to the smelter and the latter to upgrade technical efficiency on the product delivered. What follows will be a smelter's-eye view of the relative value of gold, silver, copper, lead and zinc as they each are contained in copper, lead and zinc concentrates. The variety of combinations is obviously of such a magnitude that it will be necessary to restrict the observations to fundamental concepts.

Jan 1, 1966

By A. T. Stroebel, J. A. Goodwin

Diatomite deposits, the skeletal remains of tiny aquatic plants called diatoms, are found in many parts of the world. Only a few of these deposits are of commercial value. Open pit mining is used in nearly all deposits now being worked. Processing methods range from simple drying, crushing, sizing and packaging to carefully controlled and highly sophisticated calcining and air classification procedures, employing the latest control and testing techniques. The major uses of processed diatomite are infiltration as filter aids and fillers and extenders.

Jan 1, 1983

By D. R. Weir, R. M. G. S. Berezowsky

Pressure oxidation of gold containing concentrates and ores is an effective pretreatment for liberating refractory gold. This is particularly true when an appreciable portion of the gold is associated with sulfides and is not amenable to conventional cyanidation. A brief review of the literature on pressure oxidation of refractory gold materials is presented. The chemistry of the aqueous oxidation of arsenopyrite and pyrite is discussed. Data obtained on pressure oxidation and subsequent cyanidation of concentrates and ores tested at the Sherritt Research Centre are also presented.

Jan 1, 1985