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By J. A. Bowers

THIS investigation of the effect of bottom shape and life on slag volume was carried out in two Lectromelt top-charge furnaces whose rated capacity is 1000 lb per hour. Unfortunately, just as the work [ ] was started, our steel tonnage was reduced approximately one half, therefore we did not accumulate enough data from which to draw any definite conclusions. Furthermore, the life of the linings in these furnaces was greatly decreased by intermittent operation, which was a further handicap in making a study of this kind. The weight of the heats from which the data were taken varied 1200 lb but all the information was corrected to the standard weight charge for these furnaces of 4500 lb. Almost all the heats were plain carbon; a few contained a small percentage of added copper.

Jan 1, 1947

By Harold M. Smith

Among the more important raw materials now utilized for the commercial production of synthetic organic chemicals is natural 'gas. Natural gas has been used as a fuel and source of energy almost from its discovery, but its potentialities as a chemical raw material were not realized until recently. Research in the use of natural gas for Chemical synthesis received great impetus from the discovery by Brooks and Humphrey4/ in 1918 of alcohols in the diluted ?acid oil? obtained by sulfuric acid treatment of cracked petroleum distillates. Experimental data soon showed that hydrocarbons from natural gas could be converted to these same products. Laboratory methods for chlorination of natural-gas hydrocarbons, particularly of methane for the production of methyl chloride, methylene chloride, carbon tetrachloride, and chleroform were known before that time but were not developed commercially. Methods for obtaining alcohol by oxidation of hydrocarbons derived from natural gas also were known before 1918 but had not received commercial consideration. Since 1918, and particularly during the past 15 years, the work of chemists and chemical manufacturers throughout the world has resulted in an accumulation of data regarding the reactivity of natural-gas hydrocarbons, and related hydrocarbons found in refinery gases or made synthetically. These data have been used to develop methods for converting hydrocarbons into chemical products and thus form the basis for a large and growing industry.

Jan 1, 1947

By A. M. Gavdin, F. W. Bowdish

Mineral dressing is an industrial art concerned with the treatment and separation of solids suspended in fluids. Knowledge and evaluation of the area of solid-fluid interface is important in all cases except those involving only large pieces of solid. In fact, many problems relating to comminution, to flotation, to thickening and classification, could be dealt with more rationally if the interfacial area were known. A number of methods have been proposed for the measurement of the surface of certain finely divided solids. Among them are methods using rate of dissolution of the solid,? its magnetic remanence,³ the turbidity of its suspension," and the character of the size distribution of the material.9 The first two are limited to one mineralogical species per sample; the third has certain optical limitations, especially for mineral mixtures, and the fourth is based on an extrapolation of uncertain validity. The need of a better and more general method of surface determination has long been felt, therefore. The method of P. H. Emmett,4 based upon the low-temperature adsorption of vapors, appears to fulfill this need. This method consists in determining the amount of nitrogen that is adsorbed by a given sample of solid at the temperature of boiling nitrogen. The more surface there is on the solid—both internal and external—the more nitrogen is abstracted. In actual operation, the method is somewhat less simple than has been stated so far, in that the nitrogen is adsorbed in an incomplete layer, the completeness and thickness of the layer being related to the pressure of the nitrogen in contact with the sample.2 This circumstance makes it necessary to determine the nitrogen adsorption for three or more values of the nitrogen pressure. Apparatus In the Richards Mineral Dressing Laboratories an Emmett apparatus has been built and tested (Figs. I and 2). A mechanical vacuum pump B and a mercury diffusion pump A work in series to give a high vacuum. The sample, placed in bulb D, can be evacuated by this pump train by suitable operation of the stopcocks in the glass tubing that connects the various parts of the apparatus. C is a McLeod gauge, used to ascertain the order of magnitude of the vacuum obtained, and not for accurate pressure measurements. Pressure measurements are made in the mercury manometer F and gas-volume measurements in the gas burette E. Gases are stored in flasks L (nitrogen) and K (helium), arranged so that definite quantities of these gases can be introduced into

Jan 1, 1947

By R. J. Bridges

Mining operations on the Witwatersrand are conducted for the most part in rocks of highly quartzitic character. They comprise the following types: Conglomerates, grits, and quartzites, to which on the Far East Rand must be added fine-grained quartzitic shales and shales. In addition, vein quartz occurring as small veins, veinlets and fissure fillings, and igneous rocks forming dykes, must be mentioned, although they constitute only a small percentage of the rock broken. The following is an account of the character and mineralogical composition of the various types.

Jan 1, 1947

Jan 1, 1947

By S. C. Oliphant, R. Floyd Farris

Presented in this paper is a summary of the results of experiments conducted in both the laboratory and the field during the past three years in connection with casing-perfora. tion problems. Included are studies of gun features that influence bullet performance and penetration, and studies of the effect of perforator bullets on casing and the neat cement in the annulus. Discussion and data are also presented relative to the accuracy of depth measurements in deep wells. Introduction It is a common practice in the oil industry to effect the completion of oil wells by setting and cementing casing through the producing horizons and perforating the section of casing opposite the desired interval by means of a gun lowered into the well on a cable or on the tubing. This practice has been followed for some time, and this method of completion has been given considerable study by the companies that render perforating service as well as by the oil companies that utilize their services. Through continued research on this subject, it has been possible to develop guns, bullets, and powder that will permit controlled firing at great depths, and penetration of as many as two strings of casing. It is the object of this paper to present the results of studies made of gun perforating in both the field and the laboratory. These studies were made to determine the factors that affect penetration of the bullet, burring of the casing, accuracy of depth measurements, and other items. It is hoped that by presenting the results of these investigations a better understanding may be obtained of certain of the factors involved in gun perforating and further investigation of the subject will be prompted. Subsurface Tests A well approximately 9000 ft deep, which was being prepared for abandonment, was selected for subsurface tests of gun-perforating experiments, In preparing the well for the experiment, 51/2-in. casing in the hole was pulled and racked in the derrick. A test section of pipe, which consisted of 65 ft of 5-in. 18-lb J-55 casing centered inside 7-in. 28-lb N-80 casing, was placed in the derrick corner and the annulus between the two pipes was cemented from the bottom up with 161/2 lb per gal neat cement, which was mixed and displaced with a cementing truck in the usual manner. After the cement had been allowed to harden for about a week, the test section was lowered into the hole on the 51/2-in. casing to a depth of 6600 ft by casing measurements. The hole was filled with drilling fluid weighing 10 lb per gallon. A perforating company was called to perforate the pipe, but was not advised that an experiment was being conducted. The company was asked to check the total depth (to cross pins in the bottom of the test section), then to raise the gun a given distance and fire a given number of shots with 1/2-in. bullets, pick up another distance and fire a given number of 3/8-in

Jan 1, 1947

By H. L. James

THIS paper presents the results and analysis of field trials of various magnetic instruments over anomalies ranging from 20 to 5000 gammas of vertical intensity. The following instruments were used: Askania vertical magnetometer, Wolfson vertical magnetometer (model M-I), Hotchkiss Superdips (used both parallel to and normal to the magnetic meridian, with several settings of the "sigma" angle), Lake Superior dip needle, and the dipping circle for measurements of inclination. The change in inclination over the measured anomalies ranged up to 4°; this caused pronounced changes in sensitivity of the Hotchkiss Superdip oriented parallel to the magnetic meridian. The variable sensitivity not only gives apparent displacement of crests of anomalies, particularly at high sensitivities, but also makes the data difficult or impossible to use in preparation of iso-anomaly maps. This weakness in field performance of the Superdip is shown to be eliminated by orienting the instrument normal to the magnetic meridian and measuring vertical intensity only, which in the latitude of upper Michigan is equal to 97 pct of the total intensity. The dip needle is seen to be relatively ineffectual for location of anomalies of less than 400 gammas.

Jan 1, 1947

By E. E. Wark, I. W. Wark, J. Rogers. K. L. Sutherland

Soaps have hem used as collectors for many years, but only in the last eight years have other long-chain paraffin salts been used. It may be anticipated that these newer collectors will be used mainly with nonsulphide minerals, for which the xan-thates and similar compounds are of little value. On the other hand, the xanthates are both cheap and effective for sulphide ores and seem likely to retain their present cminence in this field. During 1938 and 1939 two of us (E. E. W. and I. W. W.) commenced a comprehensive investigation of the principles underlying the use of paraffin chain salts as flotation reagents. This research was sponsored jointly by the University of Melbourne and a group of Australian mining companies. † A broad, semiquantitative survey was then made of the field covered in the present paper. This was followed in 1940 by further work by one of us (K. L. S.). In 1941 the investigation was taken over by the Division of Industrial Chemistry of the Commonwealth Council for Scientific and Industrial Research, Australia. Discovery of some principles upon which are based the flotation of minerals by paraffin chain salts was followed by their application in the development of processes for the recovery of certain strategic minerals from their ores. Promising results in the flotation of cassiterite from various ores will be described in a subsequent paper. The Paraffin Chain Salts 'he basic requirements for a "collector " in flotation are that it should form a film over the surface of the mineral to be floated, and that this film should be orientated so that hydrocarbon (nonpolar) groups form the effective surface. When modified in this way, the mineral surface possesses some degree of air avidity. All investigators would agree with Taggart, Taylor and Ince23 that such a film can be produced only if the collector compound contains an active (polar) group to attract it to the mineral surface as well as the nonpolar group. One section of this large class of polar-nonpolar compounds is the paraffin chain salts: CH3(CH2)nX where .X signifies a polar group that ionizes in aqueous solution. Though the compound can ionize, it may be a weak or a strong electrolyte, and the hydrocarbon chain may be in the cation or the anion (Table I). Many compounds of similar constitution are available, but the usual polar groups are: -Co2Na, -So3Na, -So4Na, — PO4Na2, or an aminonitrogen group, the

Jan 1, 1947

By R. F. Stilwell

There are three things that all coal consumers look for when they burn coal: (1) suitability for their particular requirements and burning equipment, (2) uniformity of shipments, and (3) quality as expressed by heating value and other chemical and physical tests. Suitability, or proper application, is determined generally from previous buying experience. It is a function of (1) the reliability and integrity of the shipper and distributor, (2) of a certain coal field or seam and of (3) uniformity and quality. Quality is limited by the location and geology of the seam and mine, the mining and preparation methods and equipment and the knowledge and ability of the personnel. Uniformity of shipments is in many ways the most important factor in coal selection. Lack of uniformity in chemical quality, size consist and treatment cause most of the customer complaints that arise from faults of the coal shipper. Lack of uniformity destroys suitability and quality standards, causing a large customer turnover, and greatly increases sales expense and reduces the net return to the operator. Oil and gas fuels are more uniform in quality than solid fuels, and there will be more gas and oil competition for coal markets after this war than before, because the size of their market is a direct function of the dimensions of their pipe lines, which have been greatly increased during the war. Present mechanical coal-cleaning equipment based upon gravity concentration has gone a long way toward giving us a coal of uniform ash content. The chart in Fig. I, by Hebley,1 shows the greater uniformity of the ash content of washed coal as compared with that of raw coal. Wide variation in the nature and amount of ash in the coal feed to the washer leads to a coal of non-uniform ash content. Mechanica1 cleaning equipment does not understand such terms as ash-softening temperature, coking properties, size consist and sulphur content. Unless the feed to the washer is uniform, the washed coal probably will not be uniform. Table I shows the ash, sulphur and ash-softening temperature of two mines in the Pittsburgh bed, both raw and washed, loaded over the same tipple; also No. 3 and No. 4 Pocahontas seams, both raw and washed, loaded from the same preparation plant. It is obvious that they must be blended or loaded separately if a uniform product is to be obtained. Why Is Blending Necessary? It was natural for the operators of captive mines producing by-product coals to recognize the necessity for blending raw coals of different quality and coking characteristics. They have had many years of experience with blending high, low and medium volatile coals at their oven plants. They have found that careful blending gives a coke of more uniform quality and better structure. Coals that could not be

Jan 1, 1947

By Enid C. Plante

INTRODUCTION To extend our knowledge of the flotation behavior of sulphide minerals, the response of the following minerals to ethyl xanthate as collector was studied by captive bubble and cylinder flotation tests: antimonite (Sb2S3), arsenopyrite (FeAsS), covellite (CuS), marcasite (FeS2), orpiment (As2S3), pyrrhotite (FeS) and tetrahedrite (4CU2S, Sb2S3). Lollingite (FeAs2) was also examined to determine if its behavior could be correlated with that of pyrite or marcasite (FeS2). EXPERIMENTAL METHOD Mineral for Flotation and Contact Tests Mineral was prepared in the manner already described' and its behavior both freshly ground and "oxidized" was studied. Tests in which the mineral was allowed to oxidize for various periods showed that a uniform response to xanthate was reached in two days or less. Oxidation Products The soluble oxidation products from most of the above minerals were measured and their effect on the flotation of the mineral studied. The mineral samples were wet ground to minus-52 mesh and deslimed, and 20 g of this material placed in 200 ml of distilled water of a measured pH value, and C02 free air bubbled through each suspension at a constant rate (about 1 bubble/sec) for 5 days. It has been shown1 that the size of the mineral is unimportant in the rate of formation of oxidation products and that probably the supply of oxygen to the mineral is the rate-determining step. At the end of 5 days the pH value of the supernatant liquid was measured again, the mineral filtered off and the soluble products determined. Methods for estimation of sulphur acids, ferrous and ferric iron and copper have already been described.1 No satisfactory method was found for antimony. Arsenic was estimated as the arsenate.2 FLOTATION OF "UNOXIDIZED" MINERALS WITH ETHYL XANTHATE AS COLLECTOR Fig I to 3, 4, 6, show the effect of alkali and cyanide as depressants for the minerals with 25 mg potassium ethyl xanthate per liter as collector at 35°C. Wark and Cox3 have shown that with ethyl xanthate as collector, galena, pyrite and chalcopyrite show a greater tolerance to cyanide and hydroxyl ions at room temperature than at 35°C. Covellite (Fig I), marcasite (Fig 2) and pyrrhotite (Fig 3) behave similarly. The independence of the curves for pyrrhotite at 35°C with respect to cyanide

Jan 1, 1947

By Nathaniel Arbiter, A. F. Taggart

The chemical reaction occurring in collection of nonmetallic minerals with amine-type collectors was early postulated by students of flotation phenomena to be metathesis between the mineral and the collector, involving exchange between the amine-bearing (aminium) ion and the cation of the mineral, and formation at the mineral surface of an oriented film of the amine salt of the mineral anion. Qualitative evidence of exchange has been obtained on several occasions at Columbia. Thus 1000 C.C. of a solution containing 495 mg of laurylamine hydrochloride was shaken 17 min. with 100 grams of barite and ground in a porcelain mill to pass a 200-mesh screen; the mixture was then set aside for 48 hr. Filtrate therefrom analyzed 476 mg. per liter of laurylamine hydrochloride. There was no substantial loss of chloride ion (78.4 mg. per liter in the original; 74 in the filtrate). No successful analyses were concluded for barium ion. Earlier, confessedly rough work with scheelite indicated a solution gain in Ca++ equivalent to about one-half the aminium ion lost. Real quantitative roof of the exchange, in the form of an established stoichiometric balance, is unknown to the authors. The data of the present paper, however, obtained from experiments designed on the basis of the exchange hypothesis, constitute strong evidence of its truth, and at the same time point the way to economic utilization of the expensive nitrogen-bearing collectors in concentration of the low-priced nonmetallic minerals. The basic postulate underlying the experiments performed was that, if the collecting reaction is of the type R+ + Y- + MX = RX + M+ + Y- where R = aminium ion, Y = the anion of the amine salt, and M and X are, respectively, the cation and anion of the mineral, the reaction should obey qualitatively the implications of the mass-action and solubility-product laws. This is to say that coating and collection should be aided by the addition to the solution of either ion (R+ or X-) of the collector-coating compound, and hindered by the addition of either of the ions M+ or y-. Experimental work comprised determination of (,) the relative solubilities of the laurylammonium salts of a variety of nonmetallic-mineral anions; and (21 the contact angles' of various minerals in solutions containing different concentrations of the postulated controlling ions. Semiquantitative flotation tests were run With barite as checks on the diagnostic character of the contact angles. The amine

Jan 1, 1947

By Edward Pesout

The McGill smelter started operations in the year 1907. The smelter furnaces were fired with run-of-mine coal on grates until April 1911, when oil firing was introduced. Oil firing continued until April 1918, when the initial coal-pulverizing plant was started.' Early Pulverizing Plant Various alterations were made to that plant during its operation, one of the more important being in connection with the system for delivering pulverized coal. In order to minimize coal-dust explosions and fires, the return portion of the main delivery line was eliminated in the year 1928. Thereafter coal-dust explosions and fires were greatly reduced. Pulverized coal was prepared at this plant primarily for the reverberatory furnaces, but for several years it was also delivered to the converting plant, roasters and power-plant boilers by a system of auxiliary fans and delivery lines. During the period March 29 to April 8, 1929, one reverberatory furnace was fired with pulverized coal produced by an Aero, type J, unit coal pulverizer with a rated capacity of 5 tons per hour. This machine actually pulverized its rated capacity but the product was too coarse. After certain regulations, a her product was obtained but the pulverizer capacity decreased and this resulted in insufficient coal for efficient furnace operation. Table I gives a comparison of the average screen analyses of the pulverized-coal products from the impact-type unit pulverizer and the regular coal-plant installation. It was definitely proved that this size and type of unit pulverizer could not furnish sufficient coal of proper fineness to give smelting results comparable to that obtained with the regular coal-pulverizing plant. The coal from this unit pulverizer was so coarse that it did not ignite or burn properly and thus did not produce the proper heat for efficient smelting. During the latter part of 1929 and the early part of 1930, experimental work was conducted with a 7-ft. o-in. by 48-in. Hardinge conical ball-mill coal-grinding unit, which was installed alongside a furnace in the reverberatory building. Results obtained from the test run indicated that this unit would furnish sufficient coal of proper fineness for good smelting.

Jan 1, 1947

By Julius Albert Krug

IN the field of mineral resources, today's problems and those we can reasonably expect in the future are so vast that nothing less than world-wide thinking and world-wide planning will suffice. I can imagine nothing more useful for the Institute to do in celebration of its seventy-fifth anniversary than to hold this conference on world mineral resources. Mineral resources are the basis of any nation's industrial production. Without expanding industrial production, the high standard of living found in the United States could not exist. Without such a standard of living it would be most unlikely that we should have a high level of culture. The hope of the world, as I see it, depends very largely on a general rise in living standards everywhere, and in the general increase of the levels of culture including a sympathetic understanding of the problems of other nations. For this reason, the proper use of the world's remaining mineral resources must be taken into account in any plans to safeguard the peace of the world. Being as exasperatingly human as human beings always seem to be,. we usually wait until almost too late to begin our plans to stave off an impending disaster. We do this as individuals, as components of particular States or Governments, and as citizens of the world. We waited, if not too late, certainly a very long time in getting started on the job of world-wide con-

Jan 1, 1947

This work was instituted to investigate the microscopic structure of brown coals by means of microtome sections cut from them. It was found to be essential to impregnate the coal with some material prior to cutting, because of its powdery and crumbly nature. Of a number of impregnating materials tried, e.g., glycerine gum, gelatine, by far the most satisfactory was paraffin wax. Samples of brown coals for section cutting must be moist. When obtained, they should be put immediately into air-tight tins, and, if they are not to be used for some time, it is desirable to keep them under water containing a small amount of formalin. If the sample is allowed to dry in air, it becomes too hard to be cut. It cannot be softened again even by prolonged soaking in water.PREPARATION OF COALSmall rectangular, blocks were cut from the sample with a chisel and a strong scalpel. The largest block prepared was 3·2 x 2·5 x 0·6 cm. The faces of the block from which sections were to be cut were approximately levelled before treatment. The block was then painted carefully on all sides with two coats of warm aqueous agar, approximately 2 %. This prevented crumbling and breakage of the block during treatment. When the agar was set, the block was placed in water, and all the air removed with a vacuum pump. The water was replaced first by alcohol, then by chloroform, by the usual step transference of a series of liquids, in each of which the block was placed for 24 hours: Ethanol %, 10, 20, 30, 50, 70, 85, 95, 100 (three changes); Ethanol-chloroform, 3: 1, 1: 1, 1 : 3, chloroform pure (three changes) '. The blocks were then embedded in paraffin of melting point 56-58°C. Fresh...

Jan 1, 1947

By W. R. Seyfried

THE problem of extracting alumina from clay and low-grade bauxites has been the subject of considerable interest for some time. The basic reason, of course, lies in the fact that known reserves of high-grade bauxite are not inexhaustible and that the present commercial process cannot successfully cope with low-grade bauxites or clay. Ultimately it may be necessary to use these poorer raw materials for all commercial operations. An unprecedented demand for aluminum during the war emergency and the constantly threatened shortage of imported bauxite caused the United States Government to take an active role in this problem. Through the National Academy of Sciences, the War Production Board and the Defense Plant Corporation, it investigated processes and finally selected four to be used in the construction and operation of four experimental plants. Each plant was to be designed in such a way as to facilitate its incorporation into a larger commercial plant should the need arise. The Chemical Construction Corporation process, or "Chemico" ammonium sulphate process as it is better known, was one of the four selected. The extensive literature and patents on record before the war generally follow one of two process-types depending upon the extracting reagent used. One group uses an acid reagent, the other an alkali. The Chemico process uses an acid reagent. For those interested in other processes described in literature, there is a short bibliography at the end of this paper. The basic steps of all acid extraction processes are: (I) to make the aluminum silicates acid soluble, (2) to separate the released alumina from impurities and insoluble gangue, and (3) to recover the reagent for re-use. THE PROCESS AS PLANNED In April 1941, a group of chemists and engineers of the Chemical Construction Corp. became interested in the problem of extracting alumina from clays and low-grade bauxites and, under the leadership of Mr. Blakeslee Barnes, Vice President and General Manager of the Company, first drafted a process in July of that year-five months prior to Pearl Harbor. The work continued in our research laboratories and with a small pilot plant. By June 1943, the work had progressed to a point where it was possible to apply for a patent on the process which was U.S. patent 2,405,426, granted August 6, 1946. Immediately prior to the development of the Salem plant, the process was envisaged to be as follows: I. The first step was to make the aluminum silicates acid soluble. It was planned: (a) Clay or low-grade bauxite would be roasted at 700 to 800°C (1292° to 1472°F), (b) The roasted ore would then be leached with hot aqueous ammonium bisulphate to form a slurry. In this way the

Jan 1, 1947

By Farnham. G. S.

It is difficult co know how to deal with this subject before a group having such mixed interests. The mining man is not coo concerned with the problems of alloy research. The engineer is more interested in properties of materials than how these properties can be achieved. The business man feels that scientific history and prognostication are not for him, predicting trends or possible developments in the economic field being a more than sufficient occupation. Yet the application of physical metallurgy research to industry is of importance to miner, engineer, and business man, for only through such application can the continuing existence of industries manufacturing or consuming metals be assured. History shows that hard work does not guarantee industrial survival. For instance, the Bessemer method of steel making superseded puddling operations; it, in its turn, has been largely displaced by open-hearth processing; later, steels made in electric-arc furnaces displaced open-hearth products in the quality field; and now, very specialized steels are being made in high-frequency rather than in arc furnaces. It is apparent then, if industry is co remain healthy, complacency must give way co imaginative planning, based on a thorough knowledge of production technique, a knowledge supplied by efficient research.

Jan 1, 1947

Jan 1, 1947

By J. F. Myers, S. D. Michaelson, F. C. Bond

THIS work was undertaken with the object of collecting plant data on rod milling, making laboratory tests on representative samples of the various ores, and arriving at a basis for comparing the relative efficiencies of different mills operating on widely different materials and under varying conditions. These efficiencies consider only power consumption and do not include the other elements of operating costs. The over-all economic efficiency may be quite different from the consumption efficiencies with which this paper is concerned. It is hoped that these collected data will be of value in indicating the most favorable conditions of rod-mill operation. Operating-plant data on 14 different installations from 11 plants throughout the United States and Canada were collected, and laboratory tests were made on samples of these ores. The plant rod mills were all operated wet, and either in open circuit or with circulating loads so small as to be negligible. Data were obtained on one roll-crushing operation at the Utah Copper Co., for comparison. The rolls were operated wet in closed circuit with 10-mesh vibrating screens, and with a high circulating load averaging about 600 pct. This particular roll operation can be considered as a model of efficiency. The collected plant data are necessarily incomplete in some instances. Each ore was assigned a code number, and the name and location corresponding to the code number are listed in Table I when permitted. [ ] The power data in every instance refer to motor input. Net power was reported by the operator for samples I-39 and I-45, and this was increased by 20 pct to compensate for motor losses and power factor. The plant rod-mill data are listed in Tables 2 and 3. In Table 2 the speeds are calculated on the basis of partly worn rod-mill liners 2 in. thick. Where D

Jan 1, 1947

By Fred J. Wright

Originally, mining machines were actuated by purely mechanical mechanisms comprising cams, levers and gear trains, which became more and more complex as demands were made for additional operations that would increase mine tonnage. To simplify these intricate machines, development engineers began utilizing the principles of high-pressure hydraulics long employed for the control of various machine tools. The resulting specificially developed hydraulic systems are. now literally the heart of the mining machine. During world war NO. 2, very little fundamental change in design was made in existing mining machines, but because of the recognition of the merits of hydraulic application to the machines of war, it is reasonably certain that hydraulics will be applied to mining machines in the future to a much greater extent. This potential future indicates that a more thorough knowledge of hydraulics and its maintenance must be incorporated in mine operation. Maintenance of high-pressure hydraulic equipment varies considerably with respect to mine practice and conditions. The success or failure is largely dependent upon the hydraulic fluid and its care. Since all successful hydraulic systems have been designed around the use of mineral oil as the fluid, a complete analysis of this prime factor should be made to make clear the requirements of the fluid in a hydraulic system. Contamination of Oil Manufacturers of mining machinery usually have specified an S.A.E. rating or viscosity index of the proper mineral oil for use with their respective machines without considering the fact that many oils will meet these specifications but will not give the desired life or efficient operation. Hydraulic fluid should be specified as a good grade of mineral oil, such as turbine oil, having rust and oxidation resistance. It must have high chemical stability, high lubricity, and proper viscosity. These factors will minimize maintenance costs by reducing wear and the consequent replacement of parts, and at the Same time will lower costs for the oil by extending its life. Rulk purchases of oil should be limited to small sealed containers provided with a Proper pouring spout, thus reducing the possibility of contamination of the oil before it reaches the mining machine. The introduction of foreign matter, such as sand, water, coal dust and residue oil left in filling containers, will cause untold damage and maintenance expense. Sand, being one of the best natural abrasives1 will soon wear the close tolerances of the various hydraulic mechanisms to an extent that will necessitate complete replacement. Water is considered normally insoluble in oil, but because of the churning action of a hydraulic system water is broken down to particles so small that they remain in suspension. This suspension is known as

Jan 1, 1947

By Sam F. Carter

FOR some time melters and metallurgists have recognized the fact that steels may be made to identical compositions as ordinarily analyzed, but with considerable variations in physical properties. Good melting practice signifies a combination of furnace operations that will produce steel with consistently good physical properties after proper consideration of cost, production efficiency, and chemical control. In acid practice, these operations may be classified fundamentally as: (I) the oxidizing boil, (2) recarburization and deoxidation, (3) slag adjustment, and (4) final deoxidation. These operations affect the properties of the steel through variations in the minute quantities of several microscopic, submicroscopic, and dissolved constituents, which are out of reach of ordinary analyses but are very influential upon the crystallographic slippage and the molecular cohesion of the structure. One of these constituents is the FeO left in solution in the steel. Herty has shown that steels high in dissolved FeO have decreased ductility and impact and increased hardness and electrical resistance. There is also much evidence that FeO in solution affects carbon solubility and diffusion, and consequently abnormality and carburizing behavior.

Jan 1, 1947