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By B. K. Miller, George E. Moore

THE Missouri fire clays are here divided into plastic and semiplastic clays occurring as widespread bedded deposits in east central Missouri and flint and diaspore clays occurring as isolated "sink-hole" deposits in the north central Ozark region. Visual inspection was the first method used in clay prospecting. Thin overburden, hard sandstone "rimrocks," and the occurrence of diaspore float made this method particularly applicable in the flint and diaspore fields. The first drilling tool used was a hand auger. One man can drill 25 to 50 ft. per day at a cost of about 35 cents per foot. Holes can be drilled to a depth of 150 feet. Spud drills are often used where the over burden is hard. This drill uses a slotted earth socket bit. A two-man crew can drill about 100 ft. per day at a cost of about 35 cents per foot. Mechanically powered auger drills have been used extensively in wildcat drilling in the past few years. This type of drill furnishes a continuous set of cuttings. The practical depth limit with this drill is 50 to 60 ft. Two men can drill 300 ft. per day at a cost of about 20 cents per foot. Core drilling is used mainly to prove a known clay deposit. A two-man crew with a No. 22 Sullivan drill can drill about 30 to 40 ft. per day in soft clay, at a cost of about $1.25 per foot.

Jan 1, 1947

By R. H. Thorpe

Longwall working in Britain developed to overcome problems arising from depth of seams causing roof and ventilation difficulties. This system became very widespread particularly in the thicker seams, where faces of up to one mile in length were not uncommon. In the thinner sections, in order to remain competitive, the longwall undercutting machine was developed. Following the development of the coal cutter, every other aspect of the face operation was examined and mechanized as it became a bottleneck to output and efficiency. The face system itself was modified and workings concentrated with the same objectives.

Jan 1, 1977

By Bernard K. Asdell

Georgia, a state seldom considered to be an important mineral producer, has one surprising feature-it is the nation's largest producer of kaolin. Kaolin is a highly important raw material in the paper, rubber, ceramic whiteware, paint and chemical industries. In 1965, more than 2.7 million tons of kaolin were produced in this state, a 150,000-ton increase over the preceding year, and production continues to climb. Strictly defined, the term "kaolin" applies to a group of hydrous aluminum silicates in which kaolinite is the predominant mineral. Kaolinite is inherently white, non-abrasive, chemically inert, and of a very fine particle size, ranging from sub-micron to 40-microns equivalent spherical diameter. An electron-micrograph of kaolinite is shown in Fig. 1. The particles finer than about 2 microns are thin, elongated plates, hexagonal in outline. The larger particles, coarser than 2 microns, are predominantly vermicular in outline with a foliated structure. Table I shows a typical chemical analysis of commercial, wet-processed kaolin compared to pure kaolinite.

Jan 11, 1967

By J. W. Snavely

WITH all the advantages of handling bulk materials by means of belt conveyor also go some problems, one of the most persistent being that of cleaning. When sticky materials are being carried; the build-up of material on the return idler rolls results in difficulty of belt training. Much attention has been given to the problem of cleaning conveyor belts, and a great variety of cleaning devices have been developed. Even the best involve troublesome maintenance, and none can completely remove the fine particles imbedded in the belt cover, which cause rapid wear of the return idler rolls, and at the same time, of the belt cover as well.

Jan 12, 1951

By Louis Ware

A leading executive finds this a bad time to "cry" about taxes. Needed reforms must cede to emergency demands.

Jan 7, 1951

Jan 1, 1897

By James M. Barker

Jan 1, 1985

By Robert C. Weed

Leaching in place at Cananea began in the 1920's on a limited scale. The first plants were small wooden boxes located underground in the Capote and Oversight mines, and output was low. Scrap iron was used as precipitant. Later several other small plants were started up. Leaching was limited entirely to underground areas, and production remained low. The Veta precipitating plant, the first on a larger scale, was put into operation in the late 1920's. After a period of intermittent service it was rebuilt in 1946 and has since been running continuously.

Jul 1, 1956

By R. S. Shoemaker, F. W. McQuiston

Mineral Occurrence Treatment Method Table Page

Jan 1, 1975

By Robert Y. Grant

This study outlines the history of metal mining in Japan and the characteristics of the industry as they existed from 1925 to 1945. Mining and milling operations are described together with the role of the Japanese Government. A description of post-hostilities conditions and the present state of the industry is included.

Jan 11, 1951

Jan 1, 1914

MANY members of the National Societies died in service overseas during the World War. No memorial to these engineers has been set up but a unique and interesting suggestion has been made. While Edward Dean Adams, Fellow of the American Society of Civil Engineers, and Associate of the Ameri-can Institute of Electrical Engineers, ,vas in Belgium last June as delegate of the National Societies, En-gineering Foundation, and Engineering Societies

Jan 12, 1927

By Earl C. Smith

Jan 1, 1935

By Earl C. Smith

Jan 1, 1935

By William E. Milligan

SELENIUM and tellurium occupy adjacent positions in the odd division of group VI of the periodic table immediately below sulfur, with atomic numbers 34 and 52 and with atomic weights of 78.96 and 127.61 .† A recent investigation has indicated the figures in Table 1 as the order of natural abundance of their isotopes. [ ] Experimentally, as a result of bombardment, many additional isotopes have been produced and studied. They are characterized by a relative short half-life. The elements of group VI in the periodic table are of great in-

Jan 1, 1953

By Sheldon P. Wimpfen, Nelson Severinghaus

13.2-1. Introduction. Man's first association with industrial minerals came at the dawn of history when a remote ancestor first put a few rocks together to protect a fire or selected colored clays to decorate his face. He was dealing with industrial minerals when he selected flint to tip his arrows or scrape a hide. From that inauspicious beginning shrouded in the mists of man's earliest history, industrial minerals have grown tremendously in importance to our civilization. The growth rate of the industrial minerals, or nonmetallic group, has been considerably greater than that of the metals group, as can be seen by the following Fig. 13.2-1: [ ] Industrial minerals produced in the five-year period of 1961-1965 had more than twice the dollar value of the metals produced:

Jan 1, 1968

By J. A. Ede

THE object of the writer is to call attention to a rather unique aggregation of economic products distributed over a line of succeeding formations about 3 mi. long, to be seen within a few miles of La Salle, Ill. Fig. 1 is an ideal section of the stratification exposed and exploited along a distance of 3 1/5 mi. in a southwesterly direction from the quarry of the Utica Hydraulic Cement Co. located near the historic site of Kaskaskia village to the Oglesby, shaft at Oglesby. No attempt has been made to cover the whole field, special mention only being made (with the exception of two places) of the operations found along the course or parallel to the direction assumed in the ideal section. I have used Fig. 2, after J. H. Bent and De Witt Kelly, to locate the relation of the La Salle anticline to the coal mines of this district and to show the operation of No. 1 and 3 mines of the Illinois Zinc Co.

Jan 9, 1919

By M. E. Wadsworth, A. E. Lewis, R. L. Braun

Experimental results obtained in laboratory leaching studies of primary copper sulfide ore in sulfuric acid systems pressurized with oxygen are interpreted by a computerized geometric model involving the movement of a reaction zone through the ore fragments. Physical properties of the ore, including size, shape, and mineral content, are considered. The leaching mechanism involves mixed kinetics and includes a surface reaction within a moving reaction zone plus pore diffusion of dissolved oxygen through the reacted portion of the ore fragment to the reaction zone. The results are applicable to conditions that would exist in nuclear solution mining or similar processes in which the ore is converted into rubble and then inundated by a leach solution adequately supplied with oxidants. Experimental results at 90°C are correlated with the model, which includes temperature-dependent parameters.

Jan 1, 1974

By Clarence P. Linville

(Pittsburg Meeting, March, 1910.) IT is recognized that, in all metallurgical operations, the greatest possible uniformity in all conditions is essential to the best results. It is the constant aim of metallurgists to secure this uniformity, and their success in this respect has been in many cases the cause of great advances in the metallurgical processes themselves. Of all such processes, the production of pig-iron in the modern blast-furnace is perhaps the most complex and the most difficult of control. Notwithstanding the great progress of recent years, there is still great difficulty in obtaining anything like uniform conditions and results in the manufacture of pig-iron. The reason is not far to seek. The ores vary in composition and physical properties, often carrying a varying amount of gangue material, unevenly distributed The coke may vary in composition, cell-structure, moisture, hardness, and other properties. The blast, the weight of which far exceeds that of any other constituent, varies in its moisture-content and consequently in its chemical composition ; and its temperature, by reason of the method of heating, is not uniform, but, besides varying from time to time with atmospheric and other outside conditions, has a maximum and minimum for every changing of stoves. Now, with regard to these variations, the modern demand for uniformity has been greatly aided. Chemical analysis has made it possible to select ores so that the composition of the charge can be kept fairly constant; coal may be obtained from a given field, and coked in the same kind of ovens under conditions which . make the fuel practically uniform ; the Gayley

Mar 1, 1910