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By Harold E. Heide

The United States is the world's largest consumer of tin and depends entirely upon foreign imports for its major source of supply. Only a small quantity of tin is produced on the North America continent. The advent of the war in Europe in 1939?brought a threat to our foreign sources of supply, and the Congress took steps to forestall shortages of tin and other metals. By authority of the Strategic Minerals Act, passed by Congress in 1939, and subsequent legislation, the Bureau of' Mines ?and Geological Survey conducted investigations of domestic tin deposits. Most of the tin that has been produced in North America came from the Seward Peninsula, Alaska.

Jan 1, 1948

By Ernest L. Corp

Seepage forces computed by a finite-element flow program are combined with gravity forces in an elastic-plastic stress-analysis program to determine the stability of mine-waste slopes. Computer output provides a cross-sectional plot of the dam or embankment showing the safety factors for each element. The combined finite-element program called SEEP-SLOPE was used to analyze several trial embankments and the 1972 Buffalo Creek Dam failure Safety factors computed by the finite-element method (FEM) were compared with those computed by Bishop limiting-equilibrium method. For individual slip circles, there was little correlation between the factors of safety computed by the two methods. Both predict failure, but FEM shows a different mode of failure plus development of potential failure zones not indicated by conventional methods. Besides having a better theoretical basis than the Bishop method, FEM requires no assumptions regarding the location or geometry of the failure surface. As a result, the program will show progressive development of a failure zone, and areas can be pinpointed where remedial measures should be taken. In addition, nonhomogeneous cross sections can be analyzed, and zones of potential piping can be defined.

Jan 1, 1975

By Richard F. Hewlett

Use of digital computers makes possible a more efficient and complete analysis of data from a mineral deposit . This computer program was written and used during an investigation into the efficiency of methods of computing grade and tonnage of ore , wherein it was necessary to make repeated computations involving different combinations of data . This investigation was part of a continuing program of sampling methods research at the Bureau's Denver Mining Research Center.2-4 This program is designed to compute tonnage and average grade for 40 cutoff grades using either the statistical or polygonal methods . tational rate is from 200 ( input bound ) to 1,400 assays per minute , depending on the use of either individual ( one assay per card ) assay- interval length or

Jan 1, 1963

By Louis A. Panek

The practice of roof bolting, now recognized as an effective method of support, is based largely on rule of thumb. Among the various applications of bolting, the support of stratified mine roof is by far the most common. The general principles relating to this type of reinforcement are presented in two companion reports; the first describes the function of the bolts, the bolting pattern, and the behavior of bolted roof (1), 2/ and the second describes the design of the models and the theory of the experimental method (2). This report presents a rational method for designing systems of vertical bolts to reinforce horizontally bedded mine roof, developed from model tests. The structure treated herein may be described as follows: The immediate roof, consisting of beds of like material and equal thickness with no bond between them, is reinforced by vertical bolts installed in straight lines across the opening; the case of suspension is excluded because the bolts are assumed not to extend above the immediate roof. The assumption is made that the behavior of the lowest bed approximates that of a rectangular plate clamped along two opposite sides (the ribs). These specifications represent approximately the roof conditions encountered in mining bedded deposits of all kinds - coal, potash, iron ore, etc. Thus, for the design of a roof-bolting system a quantitative solution to the following problem is required: For a roof composed of beds of given thickness and physical properties, how does the support depend upon the length, spacing, and tightness of the bolts?

Jan 1, 1956

By H. C. Miller

The removal of the mud sheaths that are deposited against the faces of productive oil sands during rotary drilling is one of the important problems confronting operators, especially in semidepleted fields where formation pressures are low. Unless the mud sheaths behind the perforated oil strings and, liners are removed and the sands exposed, oil cannot enter the wells. Consequently much oil that otherwise eight be produced from low-pressure sands is trapped and never recovered. Various types of perforation washers, down swabs, and agitators are used at present for breaking down the mud sheaths and. removing the disintegrated clay particles from wells after the perforated pipes have been inserted. Mechanical methods for removing mud sheaths are quite satisfactory, but prompted by tie request of certain operators in the California oil fields Bureau of Mines engineers have conducted a series of laboratory tests with the view of developing a chemical method for removing mud sheaths in oil wells that will be applicable to field conditions.

Jan 1, 1934

By H. C. Miller

The removal of the mud sheaths that are deposited against the faces of productive oil sands during rotary drilling is one of the important problems confronting operators, especially in semidepleted fields where formation pressures are low. Unless the mud sheaths behind the perforated oil strings and liners are removed and the sands exposed, oil cannot enter the wells. Consequently much oil that otherwise might be produced from low-pressure sands is trapped and never recovered. Various types of perforation washers, down swabs, and agitators are used at present for breaking down the mud sheaths and removing the disintegrated clay particles from wells after the perforated Wipes have been inserted. Mechanical methods for removing mud sheaths are :quite satisfactory, but prompted by the request of certain .operators in the California oil fields Bureau of Mines engineers have conducted a series of laboratory tests with the view of developing a chemical method for removing mud sheaths in oil wells that will be applicable to field conditions. This report describes the laboratory work and deals generally with a chemical method for removing the mud sheath, cake, or plaster deposited against the face of oil sands in drilling wells end in wells that, on being shut in temporarily during periods of overproduction of oil, are conditioned for the shutdown .period by filling the well opposite the producing formations with mud fluid. The method described in this report was devised in the San Francisco laboratory of the Bureau of Mines and, as far as the writers have been able to determine, differs from any chemical method ever used in actual wells. The method proposes to add a small amount of calcium carbonate (preferably pulverized limestone) to the mud fluids before they are introduced into the wells so that the resultant mud sheaths will be susceptible to disintegration by acid solutions when it is desired to expose the faces of the oil sands in the wells.

Jan 1, 1934

By G. D. Coe

Float-and-sink tests indicate what results are obtainable by gravity separation and rare therefore an invaluable adjunct to most coal-cleaning processes. However, it is difficult to make a direct interpretation of float-and-sink data on coal, and several systems for interpreting them have been proposed. Of these, that developed and used extensively by Bird3/, Yancey4/, and Gandrud5/ is considered by the author to be the most satisfactory. It makes use of four interrelated curves (hereafter referred to as be "washability curves"). These curves were explained by Bird in a paper6/ published in 1923, but his explanation has been regarded by some as not sufficiently

Jan 1, 1938

By C. G. Kirkpatrick

Analysis of the data produced by a wide-band, sensitive, horizontal, biaxial motion sensor has revealed several distinctive patterns before, during, and after a roof fall. The signals prior to the roof fall are similar in spectra, but one thousand times larger in amplitude, than those after the roof fall. Immediately preceding the roof fall, by two to twelve hours, five events occurred which were larger in amplitude and lower in frequency than even the large pre-roof fall background signals. An interpretation of these events is offered.

Jan 1, 1979

By Donald O. Capstick

A mineral survey of the 520-acre Quigg West Wilderness Study Area (MT-074-155) was conducted by the U.S. Bureau of Mines in 1986 at the request of the U.S. Bureau of Land Management in order to evaluate its identified mineral resources. The Wilderness Study Area is in Granite County in western Montana about 16 miles northwest of Phillipsburg and 27 mi les northeast of Hamilton, MT. Stony Mountain, a study area on lands administered by the U.S. Forest Service, is about 1 mile to the south-southwest and was studied concurrently. No mineral resources were identified in the Quigg West Wilderness Study Area, but high grade gold assays, as much as 1.24 ounce gold per ton, were obtained at the one prospect found. Samples from four workings contained significant gold; minor silver, molybdenum, and copper were also present. The prospect containing the narrow and discontinuous gold-bearing quartz vein straddles the south boundary of the Wilderness Study Area. The shear zone containing the vein projects toward the old Crescent mine, about 4.5 miles to the south, which shows a similar geologic structure.

Jan 1, 1987

By Andrew J. Fergus

A study of the flotation characteristics of columbium-tantalum minerals was made by contact-angle and microflotation methods, and the findings were confirmed by flotation of two natural ores. In the contact-angle study conditions for collection of columbite, pyrochlore, and tantalite were determined for (1) sodium oleate with a sulfonate; (2) sodium isooctyl phosphate; (3) a short-chain primary amine; (4) a long-chain primary amine; and (5) a quaternary amine. These conditions were confirmed in microflotation tests. Information about collector action on common gangue minerals was also obtained by these two methods. In batch flotation tests on a pyrochlore ore and a columbite ore, it was demonstrated that collectors selected on the basis of contact-angle and micro-flotation studies would float columbium minerals from a complex natural ore. However, multiple cleaner and scavenger flotation steps will be necessary to produce commercial concentrates. From a pyrochlore ore containing 0.54 percent Cb2O5, a 44.4 percent Cb2O5 concentrate was made containing 36.4 percent of the total Cb2O5. For a columbite are the corresponding values were: 4.35, 54.6, and 67.1 percent. During the batch flotation study, wetting agents were found to aid in the gangue-ore mineral separations.

Jan 1, 1968

By James J. Olson

Previous Bureau of Mines studies of vibrations from quarry blasts have shown that the square root of the charge-weight may be used to group particle velocity data from various charge sizes, and that empirical propagation equations may be used to estimate vibration amplitudes. Particle accelerations of the sandstone roof of the White Pine Copper mine, Michigan, were measured to determine whether similar propagation equations may be developed for underground mine blasts. Vibration data from White Pine blasts were best grouped by scaling with the square root of the charge weight. Cube root scaling did not effectively group the data. The empirical propagation equation AW1/2 = 50,000 (R/W1/2)-2.21 where A is peak-to-peak acceleration in g's, W is the zero-delay charge-weight in pounds, and R is the distance from the blast in feet, may be used to estimate maximum vibration amplitudes from production sized blasts. Vibration differences among headings and types of explosive charge (AN-FO and dynamite), while statistically significant, were not a major factor in the estimation of maximum vibration amplitudes with an empirical propagation equation. Vibration differences between types of explosive charge were larger than the differences among headings, indicating that some reduction of vibration amplitude might be gained by using AN-FO rather than dynamite. Acceleration records from both White Pine's AN-FO and dynamite production blasts show that high intensity vibrations from the delayed portions of the blast (each delay interval = 25 milliseconds) were separate events, and that the zero-delay portion of the blast produced the maximum vibration amplitudes. If the pull of the underground blast round can be maintained, a reduction of the zero-delay charge-weight may effectively reduce the maximum vibration amplitude of the blast.

Jan 1, 1970

By W. W. Adams

"A gratifying decrease is noticeable in the number of men killed in the coal minas of the United States during the past six months as compared to the quantity of coal produced.During July last year, when 221 men lost their lives, the production of coal was over 50 million tons. In January, 1920, the production had increased to 56 million tons, or 11 per cent, while the fatalities, instead of increasing proportionately, actually decreased to 166, or nearly 15 per cent. Nor is this decrease a mere accident or coincidence peculiar to the month of January, as may be seen from the following table.From the figures shown above it may be observed that the average monthly production for January and the five months immediately preceding, was 49,500,000, or only 2 per cent below that for July, while the average number of men killed was 183, or a decrease of over 17 per cent."

Mar 1, 1920

By Margaret M. Ragin

In a cooperative effort between the U.S. Bureau of Mines and the Florida Institute of Phosphate Research, with input from the phosphate industry, the conversion of phosphogypsum to sulfur has been investigated. The first step in the conversion scheme involves reduction of phosphogypsum to calcium sulfide. Effects of temperature, catalyst, reaction time, and type of reductant (carbon monoxide and coal) are discussed. It was determined that phosphogypsum could be reduced to calcium sulfide at 850° to 1,000° C using either coal or carbon monoxide as the reductant. The required temperature was lowered to 750° C using ferric oxide or magnetite as a catalyst for the reduction reaction. Results indicate that as the volatiles content of the coal is increased, reaction temperature may be decreased to obtain a given conversion, or if the reaction temperature is maintained constant, the conversion can be increased. Best results were 95- to 100-pct conversion using a high-volatile coal at 800° to 850° C. Addition of a catalyst increased calcium sulfide yield when low- or medium-volatile coals were used as reductants, but had little effect when high-volatile coals were used.

Jan 1, 1990

By John B. Goodman

This report presents a study of a modification of the precision laboratory carbonization-assay apparatus that renders the unit capable of performance at low-, medium-, and high-temperature assay levels and permits, under controlled conditions, evaluation of the relationship between carbonization temperature and the yield of pyrolysis products. Second, the interest and value derived from the temperature study data directly apply to the particular semiplant carbonization processes and techniques currently being investigated in this laboratory. Data obtained with the assay apparatus enables the fuel technologist to predict the probable yields of carbonization products from pilot-plant operations under various carbonizing conditions. Data obtained with the assay apparatus has been used to predict the product yields of industrial carbonization plants at Kemmerer, Wyo., and Rockdale, Tex. The assay provides a useful tool in detecting, from the carbonized plant product, the degree of effectiveness of pilot-plant operation. Third, the residual volatile matter in some industrial carbons has broad significance. Evaluation of the volatile material remaining with or in the carbon may be assessed through the high-temperature-assay technique. The low-temperature carbonization assay devised by the writers has proved to be a versatile tool in predicting the probable product yields from pilot-scale carbonization processes. The apparatus described in previous publications has been modified to extend the range of testing above 500° C. without impairing the accuracy and reproducibility obtained in the low-temperature range. Results presented here include product yields from a typical Texas lignite and Wyoming subbituminous-B-rank coal over the temperature range 150° to 1,000° C.

Jan 1, 1958

By J. S. Miller

The Bureau of Mines developed methods for fragmenting oil shale formations with chemical explosives to prepare oil shale for in situ retorting and to evaluate the extent of fragmentation by various methods. A combination of three methods of explosive fracturing was used: (1) The displacement and detonation of a liquid chemical explosive in a natural fracture system; (2) the use of 60-pct dynamite to relieve stress conditions of the rock around the wellbore; and (3) the use of pelletized TNT in a series of wellbore shots to fragment the oil shale. An attempt was made to seal or grout around the fragmented oil shale by drilling 67 holes and displacing approximately 200 bbl of neat cement in the fracture system to aid in evaluating the fragmented zone, Seven methods were used to evaluate the fragmented zone. The primary evaluation method was the recording of seismic waves to delineate the fragmented zone with results based on arrival time, amplitude, and record quality. The data from the seismic measurements indicated the extensively fragmented zone was approximately 95 ft in diameter and 70 ft thick. Results of the remaining methods of evaluating fractures--including air-flow tests, coring of the expected fragmented zone, elevation measurements to indicate overburden crowning, and surveys with high-speed camera, impression packer, and down-hole camera--agreed with and supported the data from seismic measurements. Further field application of explosive fracturing and evaluation methods is needed to determine when a zone of oil shale is effectively fragmented for efficient in situ retorting.

Jan 1, 1973

By W. H. Young

THE BITUMINOUS coal and lignite industry declined slightly in 1961, compared with the 1960 figures. All of the major items, production, consumption, average value, exports, and employment, declined. Even the steady upward trend in mechanization failed to materialize; the percentages of total tonnages mechanically loaded and cleaned remained the same as in the preceding year. However, tonnage per man per day increased from 12.83 tons in 1960 to 13.87 tons in 1961, owing partly to the increased tonnage produced by continuous mining machines. Also, the percentage of total production mined by stripping and by augers increased slightly. Production.-The output of bituminous coal and lignite in the United States in 1961-403 million tons-was 3 percent less than the 416 million tons produced in 1960. Production was retarded in 1961, owing largely to the business recession and reduced exports.

Jan 1, 1962

By W. Ayvazoglou

A large number of organizations interested in the search for mineral deposits have adopted the magnetic method of geophysical prospecting, as it has proved to be the most simple, convenient, and rapid, and at the same time the least expensive in comparison with other methods. According to the last statistical data, about two millions square kilo¬ meters were explored in the United States by different geophysical methods. Ninety-six per cent of this area was prospected for oil and 4 per cent for minerals. Detailed exploration by means of the magnetometer has been carried out over about 85 per cent of this surface. The great advantages offered by this method resulted in the fact that the magnetometer was tried out in most places in which geophysical methods were applied. The main purpose of such e:rploration is to obtain the maximum knowledge valuable to the geologist; therefore good geological interpretation of the results of measurements is important. The possibility of drawing practical conclusions from a map representing the results of the study of the terrane depends greatly on the accuracy with which the measurements are made. The purpose of this article is to show the different sources of error by which the work of an operator may be affected and to discuss the means by which the carrying out of a magnetic survey may be improved.

Nov 1, 1931

By R. E. Tremoureux

This paper describing the methods and costs of quarrying limestone at Sloan, Nev., is one of a series of similar papers being prepared for and published by the Bureau of Mines on this industry in the United States. These papers are designed to disseminate information regarding the methods used. The cost tabulations represent local operating expenditures only and not total production costs. It is recognized that publication of total production costs might in many instances cause embarrassment to individual producers as well as to the industry as a whole. On the other hand, operating costs are essential to the technical discussion and study of the methods Employed. The attention of the reader is specifically called to this differentiation in order that no misunderstanding of the scope of the cost tabulations shall ensue. The quarrying operations at Sloan are interesting not only from a technical viewpoint and because of the magnitude of the deposit, but also because the quarry is located in a desert region far removed from the centers of population where lime is used. The quarry and plant are in Clark County, Nev., 20 miles west of Las Vegas, which is the nearest town to the site of the Boulder Canyon Dam. Sloan is on the main line of the Union Pacific Railroad connecting Salt Lke City and Los Angeles. The latter city is 280 miles from Sloan and it is the shipping, point for all supplies.

Jan 1, 1932

By A. Gene Collins

Some of the geochemical relationships that exist between subsurface fluids and the associated geologic strata in petroleum producing areas of Louisiana have been determined. Samples of petroleum-associated water were obtained from 126 wells in Louisiana that produced from sediments of three geologic ages: Tertiary, Cretaceous, and Jurassic. The samples were trans-ported to a central laboratory for analysis of chemical composition, using standard methods, to determine if the compositions varied with the geologic strata of their source and, if so, why. The dissolved constituents were com-pared with those of a brine that was concentrated by evaporation. The concentrations of bromide, calcium, and strontium were useful in distinguishing the brines produced from sediments of a late age from those of an earlier age. The concentration ratios of Mg' (total equivalent magnesium) and bromide indicated that dolomitization probably had occurred and altered the composition of the brines. A principal-components analysis of the data indicated an inverse relationship between depth and concentrations of bromide, strontium, calcium, and lithium.

Jan 1, 1970

By C. F. Davidson

The Bureau of Mines studied the extraction of lithium from lithium-containing clays by chlorination with hydrogen chloride (HC1). In bench-scale laboratory investigations, HC1-H20 mixtures were used to selectively chlorinate lithium, but not calcium or magnesium, in lithium-containing clays. The addition of calcium carbonate to the clay was found to improve the lithium recovery. Reaction conditions found to affect the lithium recovery were ratio of clay to carbonate, reaction temperature, and HC1 concentration. The best conditions for selective chlorination of the lithium were 2:1 clay-carbonate, 750° C, and 20 wt-pct HC1. The experimental results and trends in lithium extraction are explained using thermodynamic relationships.

Jan 1, 1981