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Jan 1, 1918

By C. A. Wright

The average lead and zinc content of the ores mined and milled in the Joplin district is low as compared with that of other lead and zinc deposits throughout the United States. Because of this fact and of the high grade of the concentrates, the ratio of concentration is unusually high. Most of the operating companies have aimed to produce as high a grade of concentrate as possible in order to obtain the highest price for their product. They have done this at the sacrifice of the percentage of zinc recovered. The average percentage of zinc recovery is from 60 to 70 per cent. For percentage of recoveries from actual mill tests, see tables. The concentration is commonly effected by crushing the ore to ½-in. (12.7 mm.) size and subjecting it to a roughing and cleaning over two or more large Cooley jigs, of the Harz type, the finer sands being treated on the usual types of sand and slime tables. The treatment of slimes by flotation is being tested at several of the larger mills. Coarse Concentration When the ore has been hoisted from the mine it is dumped onto a chute leading to a grizzly made of iron bars, usually heavy rails, spaced 4 to 5 in. (101 to 127 mm.) apart. The oversize is caught on the grizzly, the mineralized pieces are broken with sledge hammers so as to pass through, and the boulders that are practically barren are sorted out by hand and trammed to the waste-rock pile. The proportion of waste rock thus sorted out varies from a fraction of 1 per cent. to 15 per cent., depending on the nature of the rock. Crushing The undersize material, 5 in. (127 mm.) or less in diameter, passes through the openings of the grizzly into the mill hopper below. From

Jan 1, 1918

By H. H. Stoek

The fundamental reasons underlying the choicc of a method of mining a coal seam are safety of operation, cheapness of producing the coal and the character of the product as a saleable article. From the standpoint of safety, open or strip coal mining is always preferable, as many of the dangers inherent to underground work are absent, such as explosions of gas and dust, falls of roof and coal, and also to a great extent those due to haulage and the use of explosives, thus eliminating three of the chief causes of accident from which about 75 per cent. of the underground accidents in coal mines occur. The conditions under which coal is stripped also make the work much safer than ordinary quarry work, as the depth of the pit is usually comparatively small. Prom the standpoint of low mining cost, there is much misapprehension and many of the costs given are misleading in that they do not take into account such items as the destruction of the surface for future use, the full cost of the removal of the overburden, depreciation, amortization, coal depletion, loss of time through floods and from bad weather in winter, etc. Coal is no doubt often put on the cars at less cost by stripping than by underground mining, but by no means always so, as is too generally assumed. In some cases coal must be obtained by stripping or not at all, because the small amount of overburden renders underground mining impossible.

Jan 1, 1918

As it is probable that a large proportion of the members of the Institute attending this meeting are connected with the metalliferous side of mining, the writer thought that, as coal and coke are required for various purposes in considerable quantities by their companies, some particulars of the coal industry might be of interest, especially when visiting such an important coal-mining centre as Newcastle. It is proposed to deal with the matter from the mining and economic point of view, as the geology has been so well and exhaustively dealt with in various publications referred to in the bibliography at the end of this paper. In the immediate vicinity of the city of Newcastle the collieries are gradually being abandoned, and during the past few years the Wickham and Bullock Island, Stockton, Hetton, Newcastle Coal Mining Company's "B," and the Australian Agricultural Co's Sea pit, have disappeared from the coal-producing list of collieries. AIl of these collieries worked the Borehole seam, from which, up to date, the largest quantity of coal has been produced in the northern district.It is the bottom seam of any present commercial value in the Upper or Newcastle coal-measures, and although the coal-in this seam has not been entirely 'exhausted in the collieries referred to, they have been abandoned for various reasons. For example, although about 60% of the seam (18 to 20 ft. thick) was left in the workings in the form of rectangular pillars under the city of Newcastle, this was not sufficient to 1?revent'the subsidence which took place about twelve years ago.Again, large quantities of coal in the Borehole seam have been left to protect the shipping arrangements at the Dyke, and other...

Jan 1, 1918

By A. E. Bellis

The time effect in reheating certain steels below the critical range is very marked. The increased toughness, shock-resisting power, and machinability of steel subjected to a long, high drawing temperature has been thoroughly demonstrated and is of practical importance, particularly in the manufacture of L'smokeless" rifle-barrel steel. The time effect in tempering is most important when a maximum drawing effect is desired, in which case the highest physical properties as well as ease of machining are important considerations. These are the conditions in drilling a rifle barrel. A hole, 0.30 in. in diameter and 24 in. long for the Springfield rifle, and 30 in. long for the Russian military rifle, has to be drilled in the heat-treated material. This barrel-drilling operation is probably the most difficult one in rifle manufacture, and anyone who has been connected with rifle manufacture knows how seriously production is affected when "hard" or non-uniform steel for barrels is encountered. The importance of high physical properties (tensile strength, toughness and resilience) in a rifle barrel is obvious. The physical properties of two different lots of barrel steel are given below. The first lot, No. 1, gave serious trouble in the drilling operation; the second gave no trouble at all. No. 1 No. 2 Elastic limit, lb. per sq. in.................... 117,450 116,800 Tensile strength, Ib. per sq. in................. 132,500 131,750 Elongation, per cent........................ 16.0 20.0 Reduction of area, per cent................... 42.1 51.0 Impact strength, ft.-lb. per sq. in.............. 450.0 520.0 This difference in machining and physical properties was due entirely to the time of reheating. The first lot was given a reheating time of 30 min., the second lot remained at the reheating temperature 2 hr. Both

Jan 1, 1918

[TWEEDY, A. M., and VOGEL, FELIX A.: The Briquetting of Flue Dust in the United States by the Schumacher Process, XLVII, [viii], 338. TWEEDY, GEORGE A., and BEALS, ROGER L.: Cyanide-Plant and Practice at the Minas del Tajo, Rosan'o, Sinaha, Mez., XLI, [xl], 324. Twin Falls plant, Peninsular Power Co., LI, 298. Twins, deformation lies in manganese steel, LI, 882. 2,000-Ton Leaching Plant at Anaconda (LAIST and ALDRICH) (With Discussion), LV, [xxiii], 866.]

Jan 1, 1918

[Queensland :-(Continued.) petrography of the Mount Morgan mine, LV, 263. Queensland tin mine and mill, Santa Barbara, Guanajuato, Mex., XXXVI, 227. Quenner disintegrator, XLI, 801; XLII, 15011. Quenstedt, F.: petroleum deposits, Suabia, XLVIII, 14881. Queretaro, Mex., silver mines, XXXIX, 360. Quicksilver: mining and reduction, LI, 110. Oceanic mine, Cambria, Cal., LI, 110. Quicksilver and iron decompose silver sulphide, XL, 872. Quicksilver deposits: China, -XL111, 49. Pacific slope, XXXVI, 1311.. Siberia, Vhdivostok district, XLIV, 16001.]

Jan 1, 1918

` LAWRENCE ADDICKS, New York, N. Y.-We have really two competitive processes for the production of electrolytic zinc. In the process used at Great Falls, the ore is roasted and the calcines leached, leaving a residue which has to be smelted; in the other method, the ore is burned, the zinc and lead fumed off, and the condensed fumes are leached. I do not think that we can yet come to any decision as to which is the better way to attack the problem. Of course if we roast first and then leach, various substances remain in the calcines which may consume sulphuric acid; whereas if we do the burning first, we obtain simply the zinc and lead oxides, with considerable sulphate, in the fume, and there is no shortage of acid. It also depends partly on the complexity of the ore. The one that Mr. Hall is treating and the ore they are treating at Great Falls are not quite alike, but I think they are sufficiently similar to make a comparison of the two methods, working in competition, on different parts of the country, very interesting. C. E. SCHWARTZ, Miami, Okla.-Mr. Hall states that the Joplin conditions are not suitable for the manufacture of electrolytic zinc. When we speak of Joplin ore in general, we consider, of course, a 60-per cent: concentrate with comparatively low iron, but if a low-grade concentrate could be made from tailings and so-called chats, then the problem would be quite different. A Joplin ore is comparatively simple to treat electrolytically, and I believe the electrolytic process would open a field for the treatment of such ores as would not be ordinarily smeltable; that is,

Jan 1, 1918

By Henry S. Rawdon

The structure of wrought iron as usually described by metallographists and workers in metal in general is that of a fairly pure iron. Impurities, if present, are usually considered as being in solid solution in the crystals of the ferrite matrix or as forming part of the ever present "slag streaks." Attention is herein directed to one type of these dissolved impurities; to the detection of such impurities, particularly in low-grade irons, and to their possible influence on the physical properties of the metal. The attention of the Bureau of Standards was first directed to wrought iron of the peculiar and unusual characteristics to be described later, in material which had failed in service and was submitted for test. The examination was extended to other grades of wrought iron, to see whether such features are of common occurrence in this class of material. MICROSTRUCTURE OF WROUGHT IRON Usual Structure The general microstructure of wrought iron is so well known that a detailed description of it here is needless. There is shown in Fig. 2 the structure of a sample of Swedish iron which illustrates well the matrix of ferrite crystals in which are embedded the slag threads so characteristic of the puddling process and the subsequent working of the material. The usual commercial product contains varying amounts of the impurities commonly associated with iron and steel, i,e,, manganese, phosphorus, silicon, and sulphur together with small amounts of carbon. Of these, the larger part of the phosphorus and some of the silicon present are held in solid solution in the ferrite while most of the remaining impurities, other than carbon, exist in the in closures of slag. Aside from the discontinuities introduced by the slag streaks the ferrite matrix has the microstructure and appearance of a pure metal. No definite orientation of the various crystals or grains is apparent; deep etching of the specimens reveals no intracrystalline features (i.e., within the grains) other than those noted in " pure " metals in general (etching pits).

Jan 1, 1918

It was customary formerly to publish an index of the Transactions about every fifth volume, but since the Institute began in 1913 to publish three volumes instead of one volume per year, this has been deemed impracticable and unnecessary. No collective index has been published since the one covering Volumes I to XXXV inclusive, excepting a short one covering Volumes XXXVI to XL inclusive. The Board of Directors, therefore, upon the recommendation of the Committee on Papers and Publications, decided to publish this index of Volumes XXXVI to LV inclusive, and thus enable members to have in condensed space the collective indexes of all the volumes of the Transactions.

Jan 1, 1918

By H. A. Coy, H. B. Henegar

The Mascot mines of the American Zinc Co. of Tennessee are situated in the Holston River valley, in Knox County, Tennessee, about 13 miles (20.9 km.) east of the city of Knoxville, and form a property of three operating shafts and one open pit. A second open pit is located at Jefferson City about 16 miles (25.8 km.) east of the Mascot mines. Geology Topography.—The principal topographical features of the region within which the zinc deposits occur is a series of parallel northeast and southwest ridges which reach altitudes of 200 to 400 ft. (61 to 122 m.) above the valley. These ridges are formed of resistant formation such as sandstone, quartzites, etc., while the valleys are occupied principally by limestone, including Knox dolomite, and by shale and other formations subject to quick erosion. The Holston River valley is wide and open with a rolling surface. Sink holes are common to the limestone portion, the general aspect of the valley being that of well-rounded hills with low intervening valleys superimposed upon which is a characteristic sink-hole topography. General Geology.—According to Keith, the rock formation of the area extends from the lower Cambrian into the Silurian. The region has undergone severe deformation with hcavy faulting, the underlying Cambrian having been brought to the surface by a series of low angle thrust faults, the strike of the faults and formations paralleling the general northeast and southwest direction of the topography and dipping at varying angles to the southeast. In general, the Cambrian quartzites, sandstone, etc., occupy the ridges while the Cambro-Si urian dolomites, limestone and shales occur principally in the valleys. Of the latter, the Knox dolomite is of particular interest to this paper in that it is the ore carrier in the Mascot area. The ore is associated with more or less irregular breccia zones, the degree of brecciation varying from a fine crushing to a breaking that involves blocks of large size. The breccia zones

Jan 1, 1918

By W. C. Phalen

Introduction............................... 100 Production and Exportation of Phosphate Rock.............. 101 Methods of Conservation........................ 101 Introductory Note........................ 101 Mechanical Methods of Conservation............... 103 Grades of Brown Phosphate Rock............... 106 Preparation of Phosphate Rock for Market, with Phases of Conservation Involved..................... 106 Removal of Overburden.................... 106 Methods of Mining...................... 107 Reworking Deposits..................• 107 Working "Cutters"................... 109 Washing and Drying..................... 111 Conservation of Fines .................... 113 Chemical Methods of Conserving Phosphate Rook.......... 113 Application in the West.................... 113 Chemistry of Process.................... 114 Substitutes for Phosphate Rock..................... 115 Natural Substitutes........................ 115 Phosphatic Limestone..................... 115 Apatite, Nelsonite and Other Minerals Containing Phosphate ... 116 . Apatite in Virginia................... 117 Guano........................... 118 Greensand (Marls)...................... 118 New Jersey....................... 118 Kentucky........................ 119 . Tennessee........................ 120 Alabama........................ 120 Excrement.......................... 120 Bones............................ 121 Artificial Substitutes....................... 121 Basic Slag......................... 121 Phosphate Rock Reserves....................... 122 Florida............... 122 .

Jan 1, 1918

[IRVING, JOHN D. :-(Continued.) Some Features of Replacement Ore-Bodies, and the Criteria by Means of Which They May be Discovered, XLII, [xlvii]. Discussions: on A Concise Method of Showing Ore-Reserves, XLIII, 714; on The Iron Deposits of Daiquiri, Cuba, LIII, 65; I on Recrystallization of Limestone at Igneous Contacts, XLVIII, 214; I on To What Extent is Chalcocite a Primary, and to what Extent a Secondary, Mineral in Ore Deposits, XLVIII, 194. minerals of gold deposits, Homestake belt, Black Hills, S. D., XLII, 54.]

Jan 1, 1918

H. A. BUEHLER, Rolla, Mo. -I consider the lead .and zinc deposits of the Mississippi Valley to be the result of descending waters. There are many features that we have not determined and yet when you see the general field relations, it seems to me that the cause and effect can be well explained by descending circulation. In the Joplin-Miami district, for instance, the ore deposits are connected with openings or with old cavity fillings which have a direct connection downward from the surface to practically 300 ft. In the Miami camp, in the western part of the field, some of the deepest orebodies are directly connected with water, channels; the same condition has been obvious and always present with the shallower ores. I speak of one deposit that I have examined more thoroughly than any other in that district, the Admiralty property, which contains large openings or caves at the deepest levels. It seems to me that waters which would pass upward through 1800 ft. of dolomite would be saturated with lime and magnesia so far as the carbon dioxide of those waters would dissolve them, and therefore, on

Jan 1, 1918

By Thomas Darlington

The obligation of an employer to the State requires certain things of him as matters of good citizenship: for instance, that his workmen shall have a living wage, that child labor shall not be employed, that injuries from accidents shall not make workmen a charge upon the State, and that the laborer's children shall have opportunity for education and to become good and useful citizens. Affairs of this kind are not taken up as philanthropy, for the officials of a corporation or a large manufacturing concern may not feel at liberty to spend the funds of their company as prompted simply by motives of kindliness; but they may spend company money on such matters because it is good business. For years, the poisonous effects of lead, phosphorus, and dust have been emphasized in books on industrial hygiene and their elimination has been urged; but the more important and everyday physiology of the workman himself has been neglected. Part of my object in writing this paper is to show how our knowledge of physiology may be applied to working conditions in everyday life. In the interest of industrial laborers, accident compensation laws have been enacted in 33 States. This has been carried forward rapidly, because it has been shown that it pays both employer and employee. A further step is the recognition of sickness and disablement independent of accidents, not only because of their immediate cost to the worker and to the employer, but because continued efficiency in work and business depends largely upon health. Some measure of the importance of health in industry can be gained by the knowledge that records kept by some companies which now make this the subject of careful inquiry show that the time lost by employees, through illness, is several times as much as that lost as the result of industrial accidents. It is true that accidents frequently result in permanent disability or death, but it is equally true that illness is also a cause of permanent disablement or death. Thus the chief difference is that the loss to the employee through accidents occurring in the course of his employment is now generally recognized as a cost

Jan 1, 1918

By D. Jenkins

The Franklin Laboratory was designed mainly for the analysis of the products from the two concentrating mills situated at Franklin and Sterling Hill, the most important determinations being the zinc, iron, manganese, lime, moisture, and silica contents of the ores. Within the last 4 years, however, it has been found advisable to examine most of our supplies, and therefore additional space and equipment was allotted for the examination of such substances as oils, greases, soaps, alloys, fuels, paints, explosives, and water. The building as shown in elevation (Fig. 1) and plan (Fig. 2) consists of a main or routine laboratory, an experimental laboratory, a water analysis room, and the other accessories such as stock room, library, sampling and drying rooms, and office. The main laboratory is further divided into a balance room and zinc analysis room. As the greater part of our determinations are volumetric, good light is a very important factor and with this in view the interior malls of the building were constructed of white enameled brick laid in Keene cement. These also have the additional advantage that they give a clean and attractive appearance to the room. The windows are large, being 76 by 44 in. and even on very dark days the light is good throughout the whole laboratory. Our zinc titration requires a constant light and as, on many days, especially in winter, the light is variable, we installed two Artificial

Jan 1, 1918

In connection with the recent visit of the Special Mission of British Ministry of Munitions to the United States, the United Engineering Societies gave a dinner to the members of the. Mission on Tuesday evening, Nov. 13. This was the only public function on behalf of the visiting commissioners while they were in New York. During the remainder of their visit they were in daily conference with bankers, merchants' associations, labor federations, and other organizations. The result of these conferences will doubtless have an important influence on the manufacture of war supplies in the United States, since it will enable our business men and manufacturers to avoid a good many of the mistakes that unfortunately occurred in England at the beginning of the war. At present, fully 90 per cent. of the employees of British munition factories are omen, and the problem of employing women in the industries of the United States will doubtless soon be encountered with increasing frequency.

Jan 1, 1918

By Luther B. Eames

The recovery of dissolved gold from slime pulp in the cyanide process was first accomplished by intermittent decantation. This simple process consists in mixing with the pulp containing the values in solution, a solution of lower gold content, settling the mixture in a tank and decanting the clear supernatant fluid. The thick pulp remaining in the tank is pumped to a second tank together with more barren-solution and again settled and decanted. After several repetitions of this operation, values are so far reduced that further washing is not profitable. The gold recovery of this process is high, but the plant required is bulky, labor cost is high and the amount of solution to be precipitated is excessive. Historical Data As early as 1901, a plant was built in the Black Hills of South Dakota by John Randall, employing the same principles but attempting to make the process continuous by substituting for flat-bottomed tanks, cones which operated continuously, receiving a constant feed and discharging a steady stream of thickened pulp. These cones were operated in series, the thick underflow of the first one forming, with a stream of diluting solution, the feed to the second cone of the series. Barren solution was added to the tank immediately preceding the discharge tank and, after being slightly enriched by the low-grade pulp in this tank, overflowed to form a diluting solution again for the richer feed entering the third tank from the end of the series, and so on back to the richest tank of the series. Clear water was used for the wash in the final tank. This is the principle on which all successful countercurrent decantation plants operate at the present time, but Randall's plant was not successful because of mechanical difficulties in getting a continuous thick discharge from his cone tanks. A similar plant was built in South Africa although there the washes were not repeatedly used, as in Randall's case, but were precipitated after each contact with the ore. This also was abandoned

Jan 1, 1918

[Murray and Renard: chondres on ocean floor, XLI, [155]. Musconetcong Iron Works, Stanhope, N. J., blnst furnace, XL, 467. MUSSEN, H. W.: Discussion on The Bogoslovsk Mining Estate, XXXIX, 897. death, XLIII, [Ixxvi]. Muzo, CoIombia: emerald deposits, LV, 910. emerald mine, XXXIX, 317. minerals, LV, 925.]

Jan 1, 1918

Jan 1, 1918