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By W. D. Brown

Newell1 has shown that hydrogen is removed from steel in a vacuum at a temperature of 500° to 900° C. within 136 hr. Holm and Thompson2 also state that, especially when the hydrogen is high, the results obtained by extraction at 800°C. agree with those obtained by vacuum fusion. In this laboratory, an apparatus was designed (Oct. 1940) and used wherein the piece of steel was heated at 100°F. in a Torricellian vacuum (Fig. I). This vacuum was produced by raising and lowering a "leveling bottle or bulb" containing mercury. Extensive tests were made with this apparatus. The weakness of the procedure was the possibility of leakage of air into the tube around the rubber stopper at the bottom. The present plan is to raise and lower the mercury by applying vacuum from a mechanical pump, to the top of the tube and then to a bottle of mercury in which the bottom of the tube is immersed. The Apparatus The extraction is made in a Pyrex tube A, I in. i.d. It is drawn down at the top at N and an 8-mm. i.d. tube is welded on it. To this a Pyrex stopcock E, 4-mm. bore, is welded. The tube between N and E is preferably 8 in. long and is graduated in milliliters. The total length of A to the stopcock is 28 inches. Heat is supplied by a split-tube furnace. 0 in. long by 6 in. in diameter, hinged on the side. A short pyrometer couple P is inserted through the walls of the furnace. In use this is standardized by comparison with a standard couple in a I-in. tube, just opposite this short couple. In the I-in. tube A a glass rod R, flattened at one end, supports the sample S and the length of R is so adjusted that the sample is in proper place. (It may float in the mercury.) The tube A is inserted in a large rubber stopper to fit the bottle B and extends nearly to the bottom. It is so placed that the handle of the stopcock faces the operator. In this stopper also is a short tube D bent at right angles for the application of vacuum. Also in this stopper is an 8-mm. tube C reaching nearly to the bottom; this is bent so as to miss the heater and again bent to bring it in line with and as near as possible to the upper and reduced part of tube A. On this tube C is welded a 4-mm.-bore stopcock H. In order that the two tubes may be as near as possible, the handle of stopcock H faces the back, or is the reverse of stopcock E. The total height of II above the bottom is 28 in. As explained later, this is the pressure-measuring tube C. The bottle B is about half full of mercury. The mercury must cover the ends of A and C by about I in. when they are evacuated. By tees T and rubber tubing RT the tubes A, C and D, the latter through the three-way stopcock M, are connected to the vacuum pump. A sheet of asbestos at K prevents the stopcocks E and H from becoming so hot that they leak. A good grade of vacuum lubricant prevents leakage of E and H. In order to measure the pressure of the

Jan 1, 1945

By John Naughton

At the General Electric ResearchLabora-tories, we have been interested in the iron-manganese system and the effect of hydrogen on the properties of these alloys. Dr. H. H. Uhlig previously has presented some of these results.' We wish now to offer some other of the data that have a bearing on the subject of this symposium. In the determination of hydrogen in the iron-manganese system by any heating Method we are presented with the problem of the evaporation of volatile manganese and the consequent adsorption of hydrogen by this evaporated metal. It seems wise. therefore, to extract gas at as low a temperature as feasible. Consequently we chose the vacuum or hot extraction method for the analyses of these alloys. The apparatus used is shown in Fig. I. The design is a modification of the apparatus described by Holm and Thompson. To limit loss of hydrogen, samples are stored in a chamber immersed in liquid air. We recommend this procedure whenever there is a question of loss of hydrogen at room temperature. Thence they are moved to the quartz furnace by means of a small magnet, where they are heated by induction to 700' to 800°C. The extracted gas is removed by the circulating pump and placed in the known volume VI (or V2). The circulating pump has been described.3 It is so designed that in spite of the fact that the outlet portion of the pump is part of the known volume, this volume is affected neither by the speed of pumping nor by the pressure of stored gas. The pump also serves to circulate the gases for analysis. The analytical system consists of a

Jan 1, 1945

By J. G. Thompson

Determinations of the hydrogen content of irons and steels invariably are subject to two serious difficulties: (I) the determination of amounts of 0.001 per cent or less of any constituent requires an analytical procedure of unusual precision and accuracy, and (2) the hydrogen content of many samples is dccidedly not stable; i.e., there is no assurance that the content at the time the analysis is made is the same as it was when the sample was taken or at some previous time in the history of the piece. In respect to both the precision and speed of the determination, the vacuum-extraction procedure for the determination of hydrogen possesses advantages over the vacuum-fusion procedure, which has been the recognized standard for the detcrmination of other gaseous elements in sted-— oxygen and nitrogen for example. The basic facts upon which the vacuum-extraction procedure is based—i.e., the evolution of gas from solid steel when it is heated in vacuum, and the fact that the evolved gas is rich in hydrogen—were observed by Graham1 many years ago. Subsequent investigations have shown that hydrogen exists in steel chiefly as interstitial solid solution (i.e., in atomic dispersion) and perhaps to some extent as hydridcs that are unstable and decompose to form atomic hydrogen. In either case practically all of the hydrogen in steel at elevated temperatures exists in the atomic condition and consequently is able to diffuse readily through the metal. In contrast to this, other gaseous elements, such as oxygen and nitrogen, normally are present in steel chiefly in the form of relatively stable compounds such as oxides or silicates and nitrates; i.e., the oxygen and nitrogen atoms are fixed in stable combinations and are not free to migrate. The only oxygen or nitrogen that can diffuse in steel is the small amount in solution (atomically dispersed) and the rate of diffusion of these atoms is much less than that of hydrogen because of their greater atomic volume and lower mobility. Consequently, it is possible to extract most or all of the hydrogen from solid steel in a reasonable time at moderately elevated temperatures, but the procedure is not applicable to the determination of oxygen or nitrogen. It is only within the last decade that these observations have been developed into an analytical procedure for the determination of hydrogen. Apparatus and Procedure The apparatus used at the National Bureau of Standards,6 for the determination of hydrogen by the vacuum-extraction procedure, is shown schematically in Fig. I. The specimen, freshly cleaned and dried,* is suspended on a fine wire within the quartz furnace tube that is connected to the reservoir system and analytical train.

Jan 1, 1945

By J. G. Mravec

The SO-called gas-tube method as developed by Hare, Peterson and Soler for determining the type and content of gases in molten steel is particularly adapted for determining the hydrogen content in molten steel. The development of this method has been quite completely discussed in a paper published by these co-workers in 1937.' The purpose of this paper, therefore, is to familiarize with this method those who arc not well acquainted with it. The principle of the gas-tube method is as fol1ows: One end of an evacuated gas tube is sealed with a very thin copper disk. when this end of the tube is immersed in a test spoonful of molten steel, the copper disk melts almost immediately, allowing a portion of the steel to be drawn up into the evacuated space. Any dissolved gases, and those produced by reactions between the components of the steel during freezing, are liberated into the unfilled portion of the sampling tube. A blob of steel that forms on the immersed end of the tube after the sample is drawn up seals up the end, making it airtight again. The evolved gases are subsequently drawn out of the gas tube through a suitable valve and analyzed by means of an Orsat apparatus. The volume of the sampling tube is sufficiently large so that a pressure considerably below atmospheric is produced after the gas evolution. The low pressure is necessary to effect a nearly complete removal of gases from the steel. Construction oF Sampling Tube The sampling gas-tube apparatus is illustrated in Fig. I. Seamless S.A.E. tubing used for section A is first cut into 7-ft. lengths. Through cxperiencc it was found necessary to use two sizes of tubing for this part, "is-in. and 3/4-in., respectively. The smaller tubing is generally used on the hotter or lower carbon steels. If the inside wall of the tube A is coated with grease or oil, it should be burned out before being machined as follows: One end is machined on the inside diameter to a depth of 34 in., so as to form a seat for a 7/8-in copper disk, which is stamped out from 0.005 to 0.007-in. thick copper sheet. The other end is machined on the outside diameter to a diameter of 1 5/16 in., to take a small reservoir or trap member I?. About 4 in. below the same end, a 1/2-in. hole is drilled to receive the 1/2-in. copper tubing leading to the large reservoir C. The inside of tube A is then thoroughly cleaned with a round wire brush, such as is generally used to clean out shotgun barrels. It is very important that the surface be absolutely free of rust or any nonmetallic coating. Next, the thin copper disk is soldered in place with low-melting silver solder.

Jan 1, 1945

By R. M. Scafe

Although hydrogen has been intensively studied in its relation to steel quality, the methods of sampling and determinations are still open to question. It is true that various procedures have been proposed but actually there has not been sufficient agreement to establish a common base from which to work. As a result, it is difficult, to say the least, to correlate the reported results of some of the investigators in this field. The present symposium, premised on methods rather than effects, should prove of considerable value. For the purpose of this discussion two methods of sampling and analysis will be considered. First, sampling of molten steel in the ingot mold by use of an evacuated tube and cylinder using conventional methods of analysis for the gases collected; second, analysis by vacuum extraction involving the use of heating equipment and the determination of the amount of hydrogen evolved from solid steel samples by measurement at reduced pressures. Both methods have been used at Duquesne Steel Works and it is believed that either may be used with considerable benefit if the limitations of each method are recognized. Evacuated Tube and Cylinder Sampling devices for gases in molten steel suggested by various investigators range from very cumbersome and complicated devices to the relatively simple evacuated tube and cylinder used by Soler for deter- mining the CO content of the bath. This latter device was adopted (Fig. I) and modified to meet conditions at Duquesne Works. The principal modifications were in placing the cylinder at the side of the tube and the use of a sleeve on the immersion end of the tube. The first modification was made so that the cylinder could be readily detached and taken to the laboratory; the second, because of the difficulty encountered in obtaining an airtight seal after sampling and because of our practice of re-using the tube. Rigid control of the method of sampling and of the handling of the sample according to plan are of primary importance in hydrogen determinations. This applies to both the sampling of molten steel and the determination of the hydrogen content of cold steel samples. Except for a few preliminary samples taken from spoons, all work on molten steels using the evacuated tube was confined to the sampling and analysis of molten steel during the pour. As mentioned, uniformity of sampling was a basic consideration. As a result, every effort was made to follow definite sampling techniques and procedures. These included control of the depth below the surface from which the sample was taken, the timing between the shutoff and taking of the sample, as well as maintenance and care of the equipment. The distance below the surface at which the sample was taken was readily controlled bv means of a crosspiece and centering device attached to the tube. The steel was poured into the mold to the hot-top junction, the tube was then lowered into the 75

Jan 1, 1945

By C. B. Post, D. G. Schoffstall

A determinatioil of the hydrogen content of molten steel by means of the Vacuum-extraction method, as reported here, consists in first casting a sample of the bath in a bomb, so that the gases evolved during solidification are trapped for analysis. A portion of the cast steel sample is then prepared and heated at a temperature of 600" to 800°C. under high vacuum, and the gaser given off during this vacuum extraction (which are shown to be hydrogen), are collected and measured. Analysis of the gases evolved on solidification and the gases in the solid sample enables an accurate determination of hydrogen in the molten steel. Fig. I shows the bomb and accessories that have been found suitable for trapping the gases evolved on solidification. The bomb is made of scamless steel pipe, approximately 7 in. long by 136 in. i.d., and welded at the bottom. An ordinary pipe cap has a vacuuni-type metal stopcock threaded and brazed in its upper end. This pipe cap fits onto the bomb by means of machined threads. A flange is brazed to the pipe at the point where the cap starts to tighten up, and a rubber gasket is placed between the flange and cap. Heavy vacuum grease is used between the flange and gasket and the gasket and cap. The weight of the complete bomb and it? interval volume is known before the sample is cast. In practice, a sample of about 400 grams of steel is poured into the bomb, the funnel quickly swung out of the way, the bomb cap spun down the threads and tightened against the gasket, and the bomb set in a pail of water to keep the gasket and vacuum grease cool. It is estimated that at least 80 per cent 01 the gases evolved from the liquid sample during solidification are trapped in the bomb."

Jan 1, 1945

By J. B. Austin

Jan 1, 1945

By T. D. Yensen, R. K. McGeary

While we have not been primarily interested in the determination of hydrogen in the alloys that we have been dealing with, we arc very glad to cooperate in this symposium on sampling and analysis for hydrogen, as we can never tell when we may find it desirable to perform such analyses. Vacuum-fusion Method Our primary interest has been oxygen and carbon, in the analysis of which we think we have become very proficient. Our oxygen-analyzing apparatus is of the vacuum-fusion type (Fig. I). This employs Dr. Derge's type of graphite cruciblc and slit sleeve, with graphite powder between, for heat insulation (Fig. 2) supported in a clear quartz bulb connected to the Pyrex glass system by means of a carefully made ground joint. The latter is kept cool by means of an air blast from a circular copper tube surrounding the joint. The crucible is heated by high-frequency induction and the 24 one-gram samples successively dropped in from the horizontal tube at the top by means of a magnet. The gases (H², CO, N2) are passed through the CuO catalyst held at 300°C. (converting CO to CO²I, H² to H²O) and the CO² and H2O frozen out in the main liquid air trap, while N2 is evacuated. At the end of the operation, shown by the termocouple vacuum gauge indicating a pressure of 10-4 mm. Hg, the analyzing system is isolated by means of the mercury cutoffs, and the CO² and H2oare determined by transferring first the CO2 and then the HzO to the small trap at the right. This is done by placing liquid air on the small trap, then removing the liquid air from the large trap for one minute, which is sufficient to evaporate the Co2 and transfer it to the small trap. The CO2 is then measured by closing the mercury cutoff at the extreme right, removing the liquid air from the small trap, warming it up to room temperature, adjusting the mercury level to one of the three marks on the glass tube (corresponding to three volumes calibrated so that I mm. Hg of CO² corresponds to 0.001, 0.002 and 0.010 mg., respectively, of oxygen) and finally reading the pressure. Liquid air is now replaced on the large trap, the mercury cutoff at the right opened, transferring the COz back to the large trap. The cutoff to the pumps is then opened, the liquid air removed for one minute, thus evacuating the CO², the pumps again cut off and the H2 O transferred to the small trap as before, except that it is now necessary to warm the large trap with a Bunsen burner in order to evaporate all the H2O. This requires about three minutes, as the inner tube must be heated to at least 100°C. In order to prevent H²O from being adsorbed on the glass walls, the glass tubing beyond the catalyst (i.e., to the right in Figs. I and 3) is kept heated to about 150°C. by means of Nichrome ribbon as shown in Fig. 3. For a I-gram sample the above amounts of oxygen (0.001, 0.002 and 0.010 mg.) 35

Jan 1, 1945

By George A. Moore

A recent survey of existing analytical results, and an attempt to correlate them with each other and with the known history and behavior of the samples, indicated that none of the commonly applied methods could be considered established as intrinsically reliable. It was. therefore, desired to attempt to establish the reliahility of some one method by external evidence. If this were to be accomplished, other methods could then be evaluated in terms of the method establibhed. The correct method was accordingly to be chosen without regard for cost, speed, or convenience; with the requirements for routine application to be reserved for 1ater consideration. The method of total combustion was chosen and submitted to a limited number of tests against primary standard samples. Considerable experimental difficulty was encountered, indicating that additional work on the experimental arrangements is desirable. While the work to (late by no means represents a completed investigation, it is helieved that the combustion method is basically sound and that its development should be continued. Choice of Method Of the several available methods, mechanical disintegration. electrochemical methods'2'3 modifications of the Sieverts experiment,% and vacuum fusion, were all judged to contain one or more factors of un- certainty not at present completely cvaluated or suhject to complete control. These methods, therefore, were considered currently unsuitable for referee purposes. Solid evolution was considered to be of doubtful significance when conducted in the alpha range. A reasonable chance for a true analysis was found for evolution in the gamma range. Preliminary tests have indicated a very slow rate for evolutioll from gamma iron. indicating a running time of possibly 100 hr. for a one-centimeter sample. Difliculty in distinguishing such slow. evolution from blank gas was anticipated, hence the method was not consitlerctl the most suitable for the present purpose. The combustion method was evaluated as being most sound on fundamental principles. The only important unknown would be to determine that the iron oxide formed did not occlude water at the tcmperaturv of the combustion.with the odvious precautions of using a sound and clean specimen, providing a system sufficiently tight to give acceptable blanks in longtime runs, and providing a suficicntly sensitive measuring system, reasonable, precise, and truthful analytical results could be logically expected. Apparatus The equipment as originally operated is shown in Fig. I, and the glassw-are in its latest modification in Fig. 2. The sulphuric acid drier and small safety tube in the upper right of Fig. I were replaced by a KOH drier and combined manometer safety tube, to permit operation at reduced

Jan 1, 1945

By B. Alexander, G. Derge W. Peifer

This is part of a research project in the Metals Research Laboratory of Carnegie Institute of Technology, sponsored by the Carnegie-Illinois Steel Corporation. In organizing our program it became apparent that the problem of analyzing molten steel for hydrogen must be divided into two parts: (I) the correct analysis of a given sample, and (2) the correct sampling of the bath. Emphasis has been placed upon these divisions in the order named because methods of sampling cannot be evaluated until a satisfactory method of analysis is available. Vacuum fusion was selected from the list of possible analytical methods because it seemed to us to offer the best possibilities for giving rapid, accurate results on solid steel samples. A number of objections have been raised against this method as usually practiced. We have sought to meet some of these by proper design of the apparatus. Experiments will be described which show that others are not valid. In the conventional apparatus the sample is held under high vacuum for a period of several hours before it is actually analyzed and one might expect considerable hydrogen to escape during this period. We have provided a means of introducing the sample to the vacuum just before analysis. Another difficulty has been that the entire apparatus has been designed primarily for the purpose of analyzing for oxygen, which constitutes upward of go per cent of the total gases evolved from the sample The volume and pressure measurements have therefore been insensitive to the relatively small amounts of hydrogen present. This difficulty obviously can be taken into account in any apparatus designed especially for the amounts of hydrogen expected. Analysis in Vacuum-fusion Apparatus A number of experiments were carried out to determine the importance of several factors that have been stated as possible sources of error or uncertainty in vacuum-fusion analysis for hydrogen; namely, that hot graphite will absorb some of the gases, that metal vapor will cause discrepancies, and that low results may be obtained as a result of the water vapor (produced by the oxidation of the hydrogen) dissolving in the butyl phthalate of the manometer, or that the blanks obtained from the apparatus are so great as to make the method inaccurate. The experiments also checked on the accuracy and feasibility of using differential freezing as a method of gas analysis in a vacuum-fusion apparatus.

Jan 1, 1945

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Jan 1, 1944

By M. Gensamer

IT has been suggested by a number of people that it would be worth while for some one to attempt to summarize or condense the proceedings of this symposium. This task has fallen to me as organizer and co-chairman. Its difficulty will be appreciated by anyone who attempts to read the whole proceedings. It is therefore with trepidation that I offer the following digest. In recent years there has been a renewal of interest in America on this subject of the cohesive strength of materials, and a growing appreciation of the need for a better theory of cohesion failure. The theories of elastic action and plastic action are well developed, particularly the former. The theory of plastic action is still in the course of development, but it is well along. Plastic action is terminated by cohesion failure and what is needed is a theory that will tell us when to expect the cohesion failure. In the past it has generally been assumed that cohesion failure will occur when a critical value of the maximum tensile stress has been reached. Many experiments have shown that this is not strictly true, and this symposium concerns itself with the failures of this simple hypothesis, and with the efforts that have been made to devise a more satisfactory theory. The most active contributor in recent years to knowledge in this field is Dr. McAdam, and he was asked to open the symposium with a summary or condensation of his papers and views. Undoubtedly it is presumptuous to attempt a still greater condensation, but perhaps it will be useful, because even his contribution to this symposium contains no summary, no concise statement of just what his contribution has bees. Dr. McAdam makes two main points. The first is that the cohesive strength is not a single valued quantity, but that it is a function of all three principal stresses and hence must be represented diagrammatically by a surface in a three-dimensional figure. Dr. McAdam has attempted so to delineate the cohesion limit, basing his

Jan 1, 1944

The Joint Session on Continuous Cast- ing, of the Institute of Metals Division and the Iron and Steel Division of the American Institute of Mining and Metallurgical Engineers, convened in the Jade Room of, the Hotel Waldorf-Astoria, New York City, on Feb. 23, 1944, at 9:15 o'clock, Carl E. Swartz presiding. C. E. SWARTZ.-It is gratifying to see so many out at what may seem an early hour for the beginning of A.I.M.E. sessions, but I think this number-some fifty or sixty of you-is an adequate expression of the interest in these processes all over the United States, and possibly in foreign countries. I would like to ask those who feel that this type of program is of value to you to write or speak to some one of the Institute of Metals Division officers and suggest other topics for symposiums. We have a feeling that some of these current practices are of interest and we believe that under proper sponsorship many of the companies will be willing to give publicity to processes such as those that will be discussed today. Also, we would like suggestions and criticisms, so that the next ones can be better. The subject of continuous casting is not new, of course. The two papers on the program this morning will adequately cover the history and some of the earlier processes, some of the theory and some of the practice, some of the reasons why these various methods did not work. I was rather interested in discovering, when thumbing through one of the A.I.M.E. publications the other night, an article on continuous casting. I was not aware that the A.I.M.E. had published any papers on continuous casting, but there may be a number. The one that I happened to find was published in the 1915 volume, on the Mellen rod- casting process, and so we might say this is not the first session in which these subjects have been under discussion. However, there have been many improvements since then in all fields of metallurgical and mechanical engineering; consequently, I think that the papers today will be a little more involved and a little more complete in their technique. The first paper today will be given by one of our gentlemen of the press, who has done one of the outstanding jobs in this country in calling to our attention some of the newer processes that are being considered and being used in the metallurgical indus-

Jan 1, 1945

By Stephen E. Erickson

MORE and more hydrocyclones are being installed in beneficiation plants. This recent rapid increase is of special interest in the history of beneficiation, since development of the hydro- cyclone appears to have swung in a circle. To avoid any chance of confusion, it would be well first to review the accepted definitions. The size of a cyclone is expressed as the diameter of the cylindrical section. Size of the inlet orifice- which may be circular, square, or rectangular- is expressed as a diameter, or as width and length, or as an area (in square inches). The angle of a cyclone is expressed as the total included angle. The overflow or finest classification fraction leaves the cyclone through the vortex finder. The underflow or coarsest classification fraction leaves through the apex opening.

Jan 8, 1957

By T. M. Morris

THE following data have been compiled from in- formation submitted by 24 plants in answer to a questionnaire sent to cyclone manufacturers and to companies using cyclones for wet classification, either for closed circuit grinding or for desliming.

Jan 8, 1957

By Russell Salter, Edwin J. King

SINCE 1950, when perhaps two or three cyclones were being tested in Arizona, the number in use has grown to about 100. Most of these have come into operation within the last two or three years, and according to information supplied by various mining companies, the number will continue to grow for several years more. In mills that have been recently constructed, cyclones dominate the fine classification field, removing grit from lime slurries, producing smelter flux, reducing concentrate thickener overloads, classifying molybdenite in grinding circuits, and conditioning flotation feed. Four major copper companies are now testing cyclones in primary grinding circuits, and one concentrator soon to begin operation will classify entirely with cyclones. In at least two instances these versatile machines have been given a vital role in the construction of tailings disposal systems.

Jan 8, 1957

By E. C. Herkenhoff

THIS subject may be controversial. Personal preferences influence the final selection of cyclones, and side issues such as costs, floor areas, head room, and ease of replacing worn parts all enter the picture, but the following comments and data should apply to most cyclone selection problems. Broadly, the uses for cyclones in wet classification may be divided into three fields: 1) Open circuit operation, for two products, in which feed rate and sizing vary and the products vary. For example, feed may be divided into a sand product and a slime product. 2) Open circuit operation, for two products, in which feed varies, one product to have constant sizing. This calls for adjustment in either the apex or the vortex aperture. 3) Closed circuit operation, the finished product to have constant sizing. Most classification jobs fall in this category.

Jan 8, 1957

By Fred D. DeVaney

MINNESOTA taconites are extremely hard, and fine grinding is required to produce an acceptable concentrate. To reduce grinding costs, waste material is rejected by magnetic separators as soon as it is liberated. Cyclones are now used in all Minnesota taconite plants to close the grinding circuits. Erie Mining Co. installed its first grinding section at Aurora, Minn., in 1948-a 9 ½ x12-ft. mill and a fine grinding section consisting of a 10 ½ x12-ft ball mill in closed circuit with a duplex 60-in. spiral classifier. Concentrates from the magnetic cobbers treating the rod mill discharge passed directly into the classifier; the ball mill discharge was also treated in magnetic separators and the concentrate from these machines also went to the spiral classifier. Both concentrates passed through ac demagnetizing coils. It is axiomatic that for proper classification the material in suspension must be well dispersed, and it follows that magnetic concentrate must be almost completely depolarized if classification is to be successful.

Jan 8, 1957

By J. W. Galpin, V. L. Minear, F. C. Sturges, B. H. Mott, R. H. Allen, W. W. Weigel, Wm. D. Owsley, R. E. Moeller

By definition the word "grout" means a thin mortar, or a kind of plaster or ce¬ment, and "grouting" means to fill up or finish with grout. The words "cement," "plaster" and "mortar" mean a substance that is used in a soft state which subsequently hardens. Thus, grouting is the filling of void space with a substance that hardens. Construction cements are the most common substances used, either by themselves or in mixtures, but the term grouting is applied quite correctly when other substances such as plastics and certain chemicals are used. Also, the use of the term grouting to cover the filling of voids with materials that do not actually become hard, such as the-flotation tailings used in grouting in the southeast Missouri lead district, should be considered correct, as some stiffening does take place and, anyway, it is a better descriptive term than any substitute. Engineers are interested in grouting because some of the materials with which they must work contain voids, and certain conditions can be improved if these voids can be filled with something solid and permanent. Grouting is done to accomplish several purposes: I. To stop the passage of fluids and gases, 2. To cement materials together to make them stronger, and 3. To prevent consolidation of materials by filling void space with something solid as a replacement for the air and water that could be forced out under load. The construction industry uses grouting extensively for all three purposes. Grouting is used to stop water percolation under and around dams. It is used to control water flow in tunnel driving and in shaft sinking. It is used to improve foundation conditions under civil engineering structures by permanently filling void space and thereby reducing settlement, or by cementing broken rock together and increasing its supporting strength. The oil and gas industry does a lot of grouting, primarily to stop the passage of gases and fluids. The search for oil at increasingly greater depths has meant greater investment per well, and the oil industry has spent large sums on development of improved drilling methods. This

Jan 1, 1948

By F. C. Sturges

[CONTENTS PAGE ................. Introduction-Grouting in Mines. By F. C. STURGES. I Use and Technique of Pressure Grouting in the Construction Industry. By V. L. MINEAR . 3 Technique of Pressure Cementing in the Petroleum, Mining, and Construction Industries. By WY. D. OWSLEY and R. E. MOELLER. ..................... 9 An Example of Controlled Pre-grouting in Shaft Sinking. By R. H. ALLEN and J. W. GALPIN. 15 ........ Solidifying Mines and Shafts Areas by Pressure Grouting. By B. H. MOTT 17 .............. Grouting in Southeast Missouri District. By W. W. WEIGEL 20] Introduction-Grouting in Mines By definition the word "grout" means a thin mortar, or a kind of plaster or cement, and "grouting" means to fill up or finish with grout. The words "cement," "plaster" and "mortar" mean a substance that is used in a soft state which subsequently hardens. Thus, grouting is the filling of void space with a substance that hardens. Construction cements are the most common substances used, either by themselves or in mixtures, but the term grouting is applied quite correctly when other substances such as plastics and certain chemicals are used. Also, the use of the term grouting to cover the filling of voids with materials that do not actually become hard, such as the flotation tailings used in grouting in the southeast Missouri lead district, should be considered correct, as some stiffening does take place and, anyway, it is a better descriptive term than any substitute. Engineers are interested in grouting because some of the materials with which they must work contain voids, and certain conditions can be improved if these voids can be filled with something solid and permanent. Grouting is done to accomplish several purposes: I. To stop the passage of fluids and gases, 2. To cement materials together to make them stronger, and 3. To prevent consolidation of materials by filling void space with something solid as a replacement for the air and water that could be forced out under load. The construction industry uses grouting extensively for all three purposes. Grouting is used to stop water percolation under and around dams. It is used to control water flow in tunnel driving and in shaft sinking. It is used to improve foundation conditions under civil engineering structures by permanently filling void space and thereby reducing settlement, or by cementing broken rock together and increasing its supporting strength. The oil and gas industry does a lot of grouting, primarily to stop the passage of gases and fluids. The search for oil at increasingly greater depths has meant greater investment per well, and the oil industry has spent large sums on development of improved drilling methods. This

Jan 1, 1947