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By William A. Beck

"INTRODUCTION Mica is found in Georgia from the Fall Line in the central part of the State to the Valley and Ridge Province in the northwest. During the past 3 years, Georgia has been one of the chief producers of dielectric mica in the United States. Since January 1945, when prices were reduced, mining has decreased until practically no sheet mica is being recovered at present.The main mica-bearing regions in the State may be classified into three districts: The Thomaston district comprising Upson, Lamar, and Monroe Counties; the Ball Ground district, comprising Cherokee and Pickens Counties; and the Hartwell district, comprising Hart and Elbert Counties. There are numerous mines and prospects in all of these districts. All have been visited from time to time by engineers of the Bureau of Mines and by members of the Federal Geological Survey. The Federal Survey has made detailed maps and reports on all of the most important ones.This report will deal with five of these properties on which the Bureau of Mines has diamond-drilled.ACKNOWLEDGMENTSIn its program of investigation of mineral deposits, the Bureau of Mines has as its primary objective the more effective utilization of our mineral resources to the end that they make the greatest possible contribution to national security and economy. It is the policy of the Bureau to publish the facts developed by each project as soon as practicable after its conclusion. The Mining Division, I. B. Moon, chief, conducts preliminary examinations, does the actual investigative work, and prepares the final report. The Metallurgical Division, O. C. Ralston, chief, analyzes samples and makes beneficiation tests."

Apr 1, 1948

By Craig C. Hustwit

A pilot-scale treatment study was conducted on a copper-zinc bearing metal mine drainage using a pipeline treatment system called the In-Line System (ILS). The objective of this U.S. Bureau of Mines study was to determine whether the ILS could be extended from the treatment of coal mine drainages to the treatment of metal mine drainages. Hydrated lime (Ca(OH)2), quick lime (CaO), and caustic soda (NaOH) were used to neutralize the drainage. A novel reagent slurry of Ca(OH)2 and type C fly ash was also evaluated. Except for Ca(OH)2-fly ash slurry, treatment performance was evaluated for all reagents at pH values of 7,8,9, and 10. The Ca(OH)2-fly ash slurry was evaluated at a pH of 10. All reagents tested neutralized the metal mine drainage and substantially reduced the dissolved metal concentrations. It was concluded that the ILS could be useful in the treatment of metal mine drainages.

Jan 1, 2010

By T. L. Iapalucci

To determine the behavior of chlorine in coal combustion, the Bureau of Mines burned 10 chlorine-containing coals, high-, medium-, and low-volatile, in a laboratory-scale pulverized-coal combustor. At carbon-combustion efficiencies of 94 to 98 percent, 1.6 to 7.1 percent of the chlorine or an average of 4 percent of the chlorine in the coal was retained in the ash; the balance, predominantly hydrogen chloride, was evolved in the combustion gas. Sulfur retention in the ash ranged from 2.3 to 10.7 percent or an average of 6.3 percent, Addition of alkali and alkaline earth carbonates to a medium-volatile coal containing 0.27 percent chlorine by preferentially reacting with the chlorine increased the Cl/S atom ratio in the ash, Lithium carbonate addition at 0.43 percent and K2C03 at 1.59 percent increased the C1/S ratio in the ash from 0.2 to 0.6.

Jan 1, 1969

By J. B. Gayle

Oven widths for experimental and commercial slot-type ovens differ appreably in most instances; the experimental ovens usually ranging from 10 to 14 inches and the commercial units from 14 to 21 inches. Application of results obtained with experimental ovens to commercial practice thus requires major extrapolations. A critical survey of the literature indicated that sufficient information about the effects of variations in oven width on the carbonizing process is not available to permit such extrapolations to be made with any considerable degree of confidence.

Jan 1, 1960

By R. C. Buehl

A pyrometallurgical process for recovering manganese from open-hearth furnace slags or low-grade manganiferous iron ores is described. The slag or ore is smelted in a blast furnace to produce spiegeleisen; the speigeleisen is then blown with air in a basic converter to give an oxide slag. This slag product contains 60 to 75 percent manganous oxide and may be considered a synthetic manganese ore. In the smelting operations coke rates for five test periods ranged from 3,255 to 4,130 lb per ton of spiegeleisen. The recovery of manganese in the spiegeleisen varied from 60 to 76 percent. Recovery increased to 83 percent when the open-hearth slag feed to the blast furnace was diluted with a high-? grade iron ore sinter to facilitate smelting. In blowing the spiegeleisen a cyclic procedure was developed that gave nearly 90 percent recovery of manganese in the slag product (synthetic ore) yet prevented excessive contamination of the slag by phosphorus and iron. The overall recovery of manganese was about 75 percent when iron ore sinter was used with the open-hearth slag in the smelting step. The metal remaining after oxidizing the manganese from the spiegeleisen contained approximately 3.5 percent phosphorus. It was refined in a basic converter by blowing with air in the presence of lime" A high--grade iron and a basic phosphate slag were produced.

Jan 1, 1965

By I. L. Feld

This Bureau of Mines report describes the development of a simple method of producing low-phosphorus hematite concentrates from certain submarginal southeastern iron ores. The investigation was undertaken to obtain additional information on the Clinton iron ore outcrops at the southwestern extremity of the Birmingham district of Alabama and to assist in the development of operating techniques that would make it profitable to use the marginal ores of this area for blast-furnace feed. Batch and continuous pilot-plant tests demonstrated that a relatively simple wet scrubbing treatment) followed by a desliming operation to reject argillaceous (clayey) gangue, consistently yielded a marketable granular hematite product. Iron losses were relatively high but could be tolerated in view of the low treatment cost.

Jan 1, 1960

By Richard F. Hewlett

Numerous populations of assays have been simulated for a range of assay values representative of low-grade mineral deposits to facilitate the study of problems encountered in evaluating these deposits. Analysis of these simulated populations of assays (obtained by using statistical probability models for the simulation) makes possible the quantification of the effects of (1) various composite assay intervals, (2) ore reserve computational methods, (3) uneven assay intervals, and (4) various cutoff grades on both the precision and the accuracy of the estimated average grade and tonnage of ore.

Jan 1, 1964

By John O. Atkins

[Experiments were conducted by the Bureau of Mines on five types of simuated lunar rock (dacite, tholeiitic basalt, vesicular basalt, pumice, and uluth Gabbro) to study the effects of various simulated lunar environments n their strength and deformational properties. Specimens were tested in an ltrahigh vacuum (UHV) system at pressures ranging from atmospheric down to 0-11 torr and at temperatures of -130°, 20°, and 135° C. All tests were onducted with a servocontrolled testing machine. Rock specimens tested at 0° C in UHV exhibited significantly higher compressive strength and Young's odulus than those tested at 20° C in atmospheric pressure. The magnitudes f increase are related to the porosities and permeabilities of the rock pecimens; high porosity and permeability allow better outgassing and thus nprove surface cleanliness in UHV. The compressive strength generally ncreases but Young's modulus decreases as test environments change from 20° C i UHV to 135° C in UHV. No significant difference was observed in the iysical properties measured at 20° C in LTV and -130° C in UHV. Anisotropy i strength and Young's modulus exist both in UHV and at atmospheric condi¬'.ons with the same symmetry pattern. The orientations of the principal axes iy, however, change from the atmospheric to UHV condition. The results idicate that rock fragmentation in lunar environment will require more ergy than that at 20° C in atomospheric pressure.]

Jan 1, 1974

By Thomas Fraser

IN a Nation-wide appraisal of coking-coal reserves and of the feasibility of expanding them by upgrading marginal coals, it is natural that the Pittsburgh region of Pennsylvania should be considered first. Here, where the American iron and steel industry started, the Pittsburgh coal bed is of paramount importance. The use of coke in iron blast furnaces is said to have begun with the discovery that good blast-furnace fuel could readily be made by a simple method of coking Pittsburgh coal. To the present time, the prosperity of the steel industry has depended largely on utilization of this great coal reserve and the cheap transportation afforded by the Monongahela River system. OBJECT AND SCOPE OF INVESTIGATION The initial project in the study of upgrading marginal coking coals was laid out in this area, which contains large reserves of Pittsburgh coal contiguous to the Monongahela and its navigable tributaries. Much of the Pittsburgh coal remaining here is known to have a high sulfur content. The problem of reducing the sulfur to meet metallurgical requirements already has received much attention, and it is considered to be one of the most difficult technologic problems in the field of coal washing.

Jan 1, 1950

By John W. Chandler

The property of the lava Cap Gold: Mining Corporation is in the Nevada City-Grass Valley mining district about 5 miles east of Crass Valley, Calif. At present (July 1940) the plant is mining end milling about 390 tons of gold-silver ore a day; about 310 men are employed. This paper describes the mining methods used and presents mining costs for 1939, when 60,704 tons were mined by cut-and-fill stoping and 55,676 tons by square-setting.

Jan 1, 1941

By Robert M. Cox

The objective of this study was to determine if significant relationships exist between coal mine roof stability and the time roof is left unsupported. Additional factors such as geology, opening geometry, and mining methods were also studied: to determine their relative influence on mine roof stability. The results of the study indicate that geologic factors such as shear zones (either joints or faults) and changes in roof rock lithology were the principal factors governing mine roof stability. The time lapse factor appeared to be of critical importance when poor mine roof conditions are encountered. The study pointed up the need for improved and permissible rock mechanics instrumentation for use in coal mine investigations.

Jan 1, 1974

By Richard D. Hagni

The character of phosphorous-bearing minerals in the Birmingham red Iron ores and iron-bearing minerals in the Eufaula bauxite deposits in Alabama has been Intensively studied by petrographic, ore microscopic, luminescent microscopic, scanning electron microscopic, electron microprobe, and x-ray diffraction techniques. A total of 15 types of phosphorous-bearing mineral grains have been recognized in Birmingham iron ores by their characteristic sizes, shapes, and distributions. Size measurements, modal analyses, and texture analyses have permitted an estimate of potential liberation of phosphorous from the iron ores by beneficiation to be 27% In areas of previous mining and 60% in areas of current iron reserves. Fine grinding, selective flocculation, and flotation may constitute the best beneficiation technique for future research. Hematite and goethite are the most important iron minerals in Eufaula ferruginous bauxites, but pyrite, marcasite, and siderite are Important iron minerals in some varieties of ferruginous bauxite, and lepidocrocite and ilmenite occur locally in minor quantities. Although simple screening will remove the coarsest iron-bearing grains, research on the utilization of high gradient magnetic separation to reduce the amounts of iron-bearing grains is recommended.

Jan 1, 1981

By R. W. Van Dolah

An investigation was made of the distances over which sympathetic detonation of ammonium nitrate (AN) and ammonium nitrate-fuel oil (AN-FO) might be expected. Large-scale gap tests used two types of AN-FO donor charges in three sizes with AN, both at ambient and elevated temperatures, and AN-FO acceptor charges. Donor sizes were varied to test the validity of a scaling law commonly used in quantity distance tables. The up-and-down experimental design was chosen to determine the 50-percent initiation point efficiently. The acceptor charges were instrumented to indicate initiation and to determine detonation velocity. Other electronic techniques for measuring the rate of growth, stability of detonation, and detonation pressures were employed. Air shock and fragment velocities between charges were measured by electronic and photographic methods, and determination of side-on air-blast pressures and impulse duration were made for about half the shots. Separation distances between donor and acceptor were found to be larger than anticipated both for the AN and the AN-FO. With AN-FO acceptors and a 16-gage steel faced donor, one initiation occurred at a separation of 53 feet or nearly 16-charge diameters; with AN, initiation occurred at 4 to 5-1/2- charge diameters.

Jan 1, 1966

By O. C. Blade

This report is one of a series made by the Bureau of Mines under a cooperative agreement with the American Petroleum Institute on the characteristics of commercial aviation gasolines. The series of Surveys is a continuation of like work conducted under aimil.ar cooperative agreements with the Coordinating Research Council, Inc. by the National. Bureau of Standards from 1940 through 1946 and by the Bureau of Mines from 1947 through 1949. A completed list of the series of surveys is given at the end of this paper.

Jan 1, 1951

By Thomas A. Phillips

The Bureau of dines present, an economic evaluation of its process for the ferric chloride leaching of chalcopyrite concentrate. In this process, chalcopyrite concentrate is leached with ferric chloride solution to extract copper, which is precipitated from the solution by electrolysis while leaving sulfur in the residue. Spent liquor from electrolysis is treated with oxygen to regenerate the ferric chloride leach solution and the sulfur-laden residue is processed to recover the sulfur. A cost estimate was prepared for a plant capable of processing 600 tons of chalcopyrite concentrate per day, 330 days per year. The fixed capital cost, on an early 1.975 basis is $27,831,600 and the estimated operating cost is 9.9 cents, per pound of copper product. In comparison, the estimated operating cost of a smelter equipped with a citrate process plant to recover sulfur is about 13.6 cents per pound of copper product. No charge for chalcopyrite concentrate or credit for recovered byproducts has been included in either operating cost. The ferric chloride leach process, therefore, appears to be economically attractive.

Jan 1, 1976

By Chase E. Sutton

The porosity of a sand is usually the measure of its capacity for holding fluid, although porosity is sometimes selective; that is, a small percentage of the actual pore space (voids), particularly in fine-grained sandstones, may be isolated by the cementing material which prevents the entrance of fluids under normal conditions. Obviously, however, porosity determinations are essential to an engineering study of underground conditions of an oil field, and a simple and reliable method of obtaining a reasonably accurate figure for average porosity is desirable. This report describes a method suggested by Ruasell,3 which was used by the writer in the preparation of a report on the Texhoma-Gose pool, Archer County, Tex.4 The conditions in this pool were particularly favorable for obtaining an average porosity figure, in that some 30 to 35 core samples of the pay sand were available for analysis.

Jan 1, 1928

By E. C. Lane

This report presents the results of the Bureau of Mines' twenty-first semiannual survey of motor gasoline marketed in the United States. The 12 cities in which samples were collected have teen chosen as representative of the more important marketing territories, as it is obviously impractical to obtain a sample of every gasoline sold in the entire country. The survey reveals that the motor gasoline which is being marketed in the United States this winter is decidedly more volatile than that sold a year ago. Samples from all cities show a decided improvement in volatility except those from Laramie, Wyo., which show a small decrease in volatility.

Jan 1, 1930

By Scott W. Hazen

In recent years many mining companies have recognized that their chance for continued economic survival depends on the adaptation of technological advances in their operations. Increased productivity through new developments in mining methods and improvements in equipment has made mining and processing of lower grade ores possible. Cost analysis has produced accurate data on the costs for development, production, and processing of ore. All of these changes and cost studies have shown the necessity for increased accuracy in determining the grade of ore. Methods of estimating grade in a mineral deposit have not kept pace with the technological advances in the other areas. The same methods are in use today as in the past. Experience and judgment are major criteria of accuracy and the results are highly subjective. In 1953, as part of its research program to develop a better understanding of fundamentals of mining technology, the Federal Bureau of Mines began a sampling method research project at its Denver Mining Research Center. The basic objective of the project is to investigate sampling methods and to study the adaptation of the techniques of statistical analysis to mine sampling.

Jan 1, 1961

By Clarence A. Wright, JAMES T. NORTON, JAMES G. PARMELEE

The object of this paper is to give to mining companies and to all others who are interested some idea of the possibilities in the treatment, by differential flotation, of lead-zinc ores of the Coeur d'Alene region and other districts. The purpose of these investiga.. tions is not to evolve a differential flotation process that would replace present methods of gravity concentration but rather one that could be applied to the relatively fine material and slime produced in the mills and treated unsuc_pessfully by gravity methods or by flotation. It is expected, of course, that the products to be obtained by differential flotation would be of much better grade than those now produced by flotation in the Coeur d'Alene mills. In view of the fact that it has been difficult to obtain representative samples of flotation feed from the mills, owing to the necessity of shipping the material wet and free from oil or other foreign matter that might be deleterious to the differential separation of the sulphides, the writers have felt justified in running flotation tests with the mill feeds in order to ascertain whether a differential separation of the sulphides could be effected. However, two different lots of flotation feed were tested for differential flotation, and the results of tests of one of these are given in this report. It is hoped that it will be possible later to test out the flotation feed for differential flotation on a large scale in some of the mills. This paper covers part of the investigations carried on by the United States Bureau of Mines in cooperation with the Idaho Bureau of Mines, the University of Idaho, and certain mining companies of the Coeur d'Alene region. Although the results of the tests included in this report are not to be considered final, they indicate possibilities and may suggest others leading to a solution of the problem of separating lead and zinc sulphides by differential flotation in the treatment of certain ores.

Jan 1, 1921

By J. P. May

This U.S. Bureau of Mines report identifies and evaluates factors responsible for dump-point accidents involving mobile mining equipment. Information regarding the occurrence and severity of the accidents, the industries affected, the types of equipment involved, the primary and contributing causes, and pertinent Federal regulations is included. The aim of this report is to provide information that will aid mine operators in the recognition of hazards associated with mobile equipment operation near the dump points of stockpiles and waste dumps.

Jan 1, 1990