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By I. Havenaar

EXPERIMENTAL DATA In an article by C. K. Ferguson and J. A. Klotz,1 experiments on the filtration of drilling muds under borehole conditions are discussed. Experimental data on mud filtration through the wall and the bottom of the hole are presented. From the data on bottom-hole filtration it was concluded that the filtrate does not flow freely into the formation, but that the pores of the formation are plugged by the mud. A quantitative interpretation of the data can be civen, by using a formula for bottom-hole filtration, dehved below. This formula is based on the following assumptions, 1. Each time a blade of a drag bit, or a cone of a roller bit, moves along the bottom of the hole, the mud cake is completely removed. 3. A new mud cake is immediately formed on the freshly produced surface, and losses of "whole" mud into the formation are negligible (this is equivalent to an immediate plugging of the pores). 3. The filtration of the mud on the bottom of the hole follows the classic law: V = A +1—(Eq. I), where t is the time required to yield a volume of filtrate V, A is the surface area of filter cake, and C is a constant. The application of this equation means that any eroding effect of the mud stream on the mud cake is neglected. The formula for the calculation of the volume of filtrate, Q,, flowing in one second through the hole bottom (diam. d cm), when using a bit with n cones or blades rotating at a rate of rn revolutions per second, is derived as follows: The mud cake is formed on the bottom of the hole in the time t =1; the filtrate volume V which passes n through the bottom In this time 1s given by Eq. 1: After1/nmsec the mud cake is removed. In one m second this process takes place nm times. Therefore the volume of filtrate, obtained in one second is given by This equation has now been applied to the experiments of Ferguson and Klotz. The constants C were derived by means of Eq. 1 from the API filter losses of the muds used by the authors (t = 1,800 sec; A = 45.16cm2). A three-cone bit was used (n = 3) at 90 rpm (m = 1.5). The calculated figures are compared with the experimental data in the table below. The calculated values of Q, are usually lower than the experimental values. This may be due to the following causes. 1. The value of C used in the calculation is based on the API filter test (filtration pressure of 100 psi), whereas the experimental data were obtained with a filtration pressure of 200 psi. Although the effect of the pressure on C is not large, C decreases somewhat with increasing pressure, and this leads to a higher filtration rate. 2. Mud losses and the eroding action of the mud stream on the cake are not entirely negligible. 3. The values of Q, derived by Ferguson and Klotz from their experiments are too high, because of their assumption that all pore liquid within the formation drilled is picked up by the drilling mud. It is found, however, that the calculated values of Qf, except in the case of oil base muds, are of the right order of magnitude. ACKNOWLEDGMENT The author wishes to thank the management of the Koninklijke/Shell-Laboratorium, Amsterdam, for permission to publish this note.

Jan 1, 1957

By Walter O. Snelling

Continuation of the discussion of the paper of WaltER o. SnelLIng, presented at the New York and San Francisco meetings, February and September, 1915, respectively, and printed in Bulletin No. 100, April, 1915, pp. 695 to 704 and Trans., li, pp. 657 to 671. A. C. McLaUghlin, San Francisco, Ca1.—It seems to me that Mr. Snelling's work, if it is what it appears to be, is one of the most important contributions to petroleum technology that has been brought out in the last 25 years. If his end products are what they seem to be, he has made. a discovery, which, in my judgment, will revolutionize the petroleum industry. As to industrially carrying out these processes I do not think there is the slightest difficulty, for I have had some work recently where crude oils were handled successfully at a temperature of 750" F, and pressure of 750 lb. per square inch. William A. WillIams, San francisco, Ca1.—What metal did you use, Mr. McLaughlin? A. C. McLauGHILIN.—Ordinaly seamless tubing, extra strong. William A. Williams.—Tests were made in Dr. Rittman's experimental plant at Pittsburgh, upon samples of residuum furnished by Mr. Bell, the residuum being the remainder of the crude oil after the lighter fractions had been removed. After the material had been run through Dr. Bittman's plant, yields of from 43 to 58 per cent. of material, boiling under 150" C. were obtained. The distillate had a peculiar odor, due to the presence of benzene, toluene, and other unsaturated hydrocarbons. W. N. Best, New York, N. Y.—What is the difference between the Rittman and the Snelling process or system? William A. Williams.—he fundamental difference is that reactions take place under relatively higher temperatures and pressures and with none of the oil present in its original or liquid state, while the reactions secured by Mr. Snelling and other investigators have been from the liquids in the presence of some vapors. Under such conditions as Mr. Snelling operates, the temperatures and pressures used are limited and the flexibility in the control of these variables is extremely limited when compared with the Rittman process.

Jan 1, 1916

By H. H. Rachford, and J. D. Rice

The effectiveness of digital computing machines in making technical calculations depends on how well the work is arranged to utilize the capability of the machines. This note presents a particularly useful way of calculating hydrocarbon vapor-li.quid equilibrium in the flash vaporization (or condensation) system. The method is well suited to sequence-controlled computing equipment. It is not limited to equilibrium calculations and may be used for solution of most implicit equations in one variable. INTRODUCTION There is increasing interest in the use of electronic digital computers in research and engineering calculations. This is a fortunate and inevitable trend in view of both the increasingly extensive numerical work which is becoming a routine part of many daily production operations and growing demand for the overwhelming amounts of calculations required by newly developed numerical methods for solving heretofore unsolved problems. Machines are in many ways ideally suited to the task but of necessity present certain difficulties. for a particular poblem to be solved must often be formulated quite differently from the way it would be arranged for manual solution. This is done in order to take advantage of the inherent speed and precision of electronic computers and at the same time to limit the need for number storage to the capacity of the machine. Therefore, this note is submitted to present a general and quite powerful method of finding solutions of the frequently encountered implicit equation: F(x,y1,y2,...ya)=0.......(1) where the root, x, is to be found for a given set of y1, ... yn.. The procedure is well suited for use with computing machines, for it usually requires but little storage or programming beyond that necessary to evaluate F. HYDROCARBON EQUILIBRIUM The method is described in terms of the problem it was designed to solve, i.e., the calculation of hydrocarbon vapor-liquid equilibrium in flash vaporization. Given the composition of a hydrocarbon mixture and appropriate values of the equilibrium ratios K, to find the phase ratio and compositions in a closed system: let z, be the mol fraction of the i-th component in the mixture. If K, is the ratio yl/xl, where y, and x,

Jan 1, 1952

By T. Busch, R. A. Dodd

The solubility of hydrogen in pure iron and pure nickel, and of nitrogen in pure iron, has been determined and agrees well with earlier data. Nitrogen is insoluble in pure nickel and cobalt. The solubility of nitrogen in Fe-Ni alloys also confirms earlier- work. The solubility of hydrogen in Fe-Ni alloys increases non-linearly with increase in nickel content, but the solubility of hydrogen in Ni-Co and Fe-Co alloys reaches a minimum at 75 and 50 at. pet, respectively. The solubility of nitrogen in Fe-Co alloys decreases approximately linearly with increase in. cobalt content. Nitrogen is insoluble in Ni-Co alloys. Determined interaction parameters are in good agreement with predictions of Gokcen and Ohlani. THE solubility of hydrogen and nitrogen in liquid iron and iron alloys has been studied by various investigators.'-l' The method of solubility measuremerit due to Sievertsl is usually preferred when the vapor pressures of the liquid components are sufficiently small, but other techniques such as sampling the equilibrated melt and then analyzing by vacuum fusion have been used quite often. Previously reported data on the solubility of hydrogen and nitrogen in ostensibly pure liquid iron are summarized in Table I; certain of the quoted results were obtained by interpolation of the published data. Agreement between the various investigators is only fair, indicative of the experimental difficulties involved in obtaining gas solubility data. The only report found on the solubility of hydrogen in pure nickel is that of Sieverts.2 The solubility of nitrogen in iron-nickel alloys has received some attention, 10, 11 the results indicating that the solubility decreases with increase in nickel content, becoming zero for pure nickel. There is no published information on the solubility of these gases in either pure cobalt or alloys containing cobalt EXPERIMENTAL PROCEDURE Sieverts' method of solubility measurement was used throughout the investigation. The construction of the melting chamber is somewhat different from A. Optical pyrometer F. Alundum cover B. Vycor chamber G. Alumina crucible C. Furnace coils H. Alundum sand D. Glass water jacket I . Alundum thimble E. Chamber support J . Detachable vycor base sealed with de Khotinsky cement

Jan 1, 1961

By R. V. Wheeler

A matter of much concern at present to the coal-mining industry of Great Britain is the effect of the working of the Coal Mines Act, 1930. This Act, which received the Royal Assent on Aug. 1, 1930, contains five parts: (1) production, supply and sale of coal; (11) the reorganization of the coal-mining industry; (111) hours of work; (IV) the Coal Mines National Industrial Board; (V) general. The first three parts are of major interest and discussion can be confined to them. Part I.—Production, Supply and Sale of Coal Under Part I of the Coal Mines Act, 1930, provision is made for central and district schemes to regulate the production, supply and sale of coal by the fixation of standard tonnage, quota and minimum prices. By Nov. 1, 1930, all the district schemes came into force with the exception of that for Scotland, where the majority of the coal-owners did not see their way to accept the amendments to their draft scheme demanded by the Mines Department. A compulsory scheme for Scotland was thereupon prepared by the Mines Department and put into force on Nov. 24, 1930. It is administered by the coal-owners of the district. The essence of the schemes is the allocation of tonnage for each district by a Central Council, and the allocation of quota for each pit in a district by an Executive Board for that district. Up to Dec. 31, 1930, the various bodies of coal-owners engaged in administering the schemes were employed in work preliminary to their full operation. Standard tonnages had to be determined and coals had to be classified. In consequence, it was not found possible to put the regulation of output into force until Jan. 1, 1931. The determination of minimum prices proved to be an even longer process, and only in a few districts were minimum price schedules operative during the first quarter of this year. The working of the schemes during the March quarter, 1931, has been reviewed in an official publication by the Mines Department,' which can be summarized as follows:

Jan 1, 1932

By R. A. Vandermeer

It is usually assumed that the rate-determining step in the migration of a grain boundary involves the thermally activated transfer of single atoms across the interface. Chemical reaction rate theory then gives a migration rate which is proportional to the driving force when this is small compared to kT.1 In their recrystallization studies on aluminum, Gordon and vandermeer2 obtained data which was capable of providing the first experimental test of this proportionality. They correlated stored energy (driving force) release measurements determined calorimetrically with fraction recrystal-lized kinetic (growth rate) data acquired metallo-graphically at a temperature where a significant amount of recovery takes place concurrently with recrystallization. Within experimental error, the results of Gordon and Vandermeer confirmed experimentally, at least over a limited range, the linear dependence of boundary migration (growth) rate on driving force in accordance with theory. In obtaining these results, however, an incorrect, implicit assumption was made in relating the average instantaneous growth rate of the recrystallized grains to the measured fraction recrystallized kinetic data. The purpose of this present note is to point out and correct this assumption. An alternate approach, whereby a more proper average growth rate can be calculated from the recrystallization kinetic data, is presented. The earlier data, reevaluated in terms of this new approach, show the same general trend as before so that the original conclusion of Gordon and vandermeer2 is still valid. As was shown in a detailed study3 of the geometrical features of recrystallization in aluminum, the colonies of recrystallized grains can be regarded as uniform cylinders embedded in a three-dimensional matrix, the number of such colonies being constant. Thus during the early stages of recrystallization the volume fraction recrystallized, Xv, can be written as Xv=ynvlr2 [l] where y is a shape factor and i and r are defined as the average length and radius of a recrystallized colony and are spatial averages over the specimen. -nv, is the number of such colonies in a unit of volume. The erroneous assumption made in the earlier paper2 was that r in Eq. [I] could be replaced by

Jan 1, 1965

The members of the Institute have probably seen in the daily papers notices of the plans of the Secretary of the Navy to. form an Advisory Board to assist the Government to make available the latest inventive genius of the country. Secretary Daniels has appointed Mr. Thomas A. Edison Chairman of this Advisory Board and has officially invited the Institute to secure the selection of two of its members to serve. on this Board. The Secretary in his letter states: "I feel that the work your Institute has done has been such as to give it the right to be in a way officially represented, and the Navy Department desires in this way to testify to its own appreciation of the splendid work for our country that your Institute has done. I have the emphatic approval of Mr. Edison, and he agrees entirely with me that your Institute should he represented in this way and that no better method of getting the kind of men we need could be devised." The invitation of the Secretary of the Navy has been officially accepted and steps have been taken to nominate the two members. Since the Constitution provides for no meeting of the Board of Directors until September, and as Secretary Daniels urged early action, the matter was discussed at a special meeting of the Executive Committee of the Institute, at which were present as many members of the Board of Directors as were in New York City at the time. Invitations were also extended to other members of the Institute who happened to be in the vicinity. At this meeting it was decided to submit the matter by a special letter-ballot to the Board of Directors and in doing so to suggest or nominate five members of the Institute, accompanying this nomination with the statement that the Directors might vote for two of the members so nominated or for any other members of the Institute not so nominated. It was voted at this meeting that it. was the sense of those present that in view of the fact that this committee was an advisory one the type of men to be chosen should be men of administrative or executive ability, cap-

Jan 9, 1915

By Eckley B. Coxe

IN the anthracite coal regions of Pennsylvania the custom has been to sight either at an open light (generally a mine-lamp), or at the string of a plumb-bob. If the station was intended to he a permanent one, a spud, as it is called, that is, a nail resembling a horseshoe nail with a hole in the head, is driven into the timbers over the station, or, if there be no timber, a hole is drilled in the coal or rock roof, into which a wooden plug is driven, which serves to hold the spud. The first operation in making a survey is to lay out the stations, that is, to mark the place where the holes are to be drilled for the plugs or the points on the timbers where the spuds are to be driven in. This should be done before any instrumental work is begun, as much labor can generally be spared, and the use of very short sights can often be avoided, by carefully laying out the stations beforehand. When the stations were laid out, a plumb-bob was hung from the innermost spud, which I will call No. 1, the instrument was put in position at No. 2, by plumbing down and putting a centre-pin under the spud, and then setting up over the centre-pin, and another plumb-bob was suspended from No. 3. If great accuracy was not required, a mine-lamp was set up under the plumbbobs, at No. 1 and No. 3, and the engineer sighted at them. If great accuracy was required, a lamp or some white sbface was held by an assistant behind the strings of the plumb-bobs. To work with any speed by the latter method (i. e., the accurate one), it was necessary for the engineer to have three assistants on whom he could rely even when the chaining was done afterwards; viz. : one to hold the light behind the string at No. 1, one at No. 3, and an assistant at the instrument to hold the light while levelling, reading the in

By Eckley B. Coxe

IN the anthracite coal regions of Pennsylvania the custom has been to sight either at an open light (generally a mine-lamp), or at the string of a plumb-bob. If the station was intended to be a permanent one, a spud, as it is called, that is, a nail resembling a horseshoe nail with a hole in the head, is driven into the timbers over the station, or, if there be no timber, a hole is drilled in the coal or rock roof, into which a wooden plug is driven, which serves to hold the spud. The first operation in making a survey is to lay out the stations, that is, to mark the place where the holes are to be drilled for the plugs or the points on the timbers where the spuds are to be driven in. This should be done before any instrumental work is begun, as much labor can generally be spared, and the use of very short sights can often be avoided, by carefully laying out the stations beforehand. When the stations were laid out, a plumb-bob was hung from the innermost spud, which I will call No. 1, the instrument was put in position at No. 2, by plumbing down and putting a centre-pin under the spud, and then setting up over the centre-pin, and another plumb-bob was suspended from No. 3. If great accuracy was not required, a mine-lamp was set up under the plumb-bobs, at No. 1 and No. 3, and the engineer sighted at them. If great accuracy was required, a lamp or some white surface was held by an assistant behind the strings of the plumb-bobs. To work with any speed by the latter method (i. e., the accurate one), it was necessary for the engineer to have three assistants on whom he could rely even when the chaining was done afterwards; viz.: one to hold the light behind the string at No. 1, one at No. 3, and an assistant at the instrument to hold the light while levelling, reading the in-

Jan 1, 1873

By Henry P. Ehrlinger

The Alta and St. Louis mines of the Alta Mines, Inc., produce a somewhat oxidized ore with a talc gangue that presents quite a problem in milling. For several years the mill recoveries were relatively low and there seemed to be no cure for this condition even with increasing the various collecting agents and frothers to two or three times of what they should be. The usual alibi of "oxidized ore" was given as the reason for these results and the matter stood there for some time until these investigations were started. Flowsheet As a brief outline of the flowsheet the ore is crushed to minus I in. in a Telsmith jaw crusher and then fed to a 64½ Marcy grate mill. The resulting product from the grate mill is passed over a trommel where the coarse particles (plus 7 mesh) are returned to the grinding circuit through the classifier. The under 7-mesh pulp is passed over two Denver mineral jigs where a high grade concentrate is produced, thence over two Wilfley tables where a table concentrate is produced and about 80 pct of the oxide lead recovered. The tailings from these tables are pumped back to the classifier and after classification the 30 pct pulp density product, which overflows the lip, is passed into a series of 10 Denver economy flotation cells where a lead-copper concentrate is produced. Three products are made and shipped to the smelter termed jig, table and float concentrates. Results with various Reagents In March of this year work was started on the metallurgical problems of the mill and, as is shown in Table I, the results obtained were not too efficient. Tests were run with various reagent combinations that were recommended for ores of this nature but there was no appreciable effect on the recoveries. The grades of the flotation concentrates were reduced by the insoluble picked up and retained by these more powerful collectors and frothers. Results with "Metso" In past work on ores of this type the use of "Metso" had improved gold and lead recoveries, but no effect on the silver and copper recoveries had been noted. To

Jan 1, 1949

By Henry P. Ehrlinger

THE Alta and St. Louis mines of the Alta Mines, Inc., produce a somewhat oxidized ore with a talc gangue that presents quite a problem in milling. For several years the mill recoveries were relatively low and there seemed to be no cure for this condition even with increasing the various collecting agents and frothers to two or three times of what they should be. The usual alibi of "oxidized ore" was given as the reason for these results and the matter stood there for some time until these investigations were started. FLOWSHEET As a brief outline of the flowsheet the ore is crushed to minus I in. in a Telsmith jaw crusher and then fed to a 64 1/2 Marcy grate mill. The resulting product from the grate mill is passed over a trommel where the coarse particles (plus 7 mesh) are returned to the grinding circuit through the classifier. The under 7-mesh pulp is passed over two Denver mineral jigs where a high grade concentrate is produced, thence over two Wilfley tables where a table concentrate is produced and about 80 pct of the oxide lead recovered. The tailings from these tables are pumped back to the classifier and after classification the 30 pct pulp density product, which overflows the lip, is passed into a series of 10 Denver economy flotation cells where a lead-copper concentrate is produced. Three products are made and shipped to the smelter termed jig, table and float concentrates. RESULTS WITH VARIOUS REAGENTS In March of this year work was started on the metallurgical problems of the mill and, as is shown in Table I, the results obtained were not too efficient. [ ] Tests were run with various reagent combinations that were recommended for ores of this nature but there was no appreciable effect on the recoveries. The grades of the flotation concentrates were reduced by the insoluble picked up and retained by these more powerful collectors and frothers. RESULTS WITH "METSO" In past work on ores of this type the use of "Metso" had improved gold and lead recoveries, but no effect on the silver and copper recoveries had been noted. To

Jan 1, 1947

By Oliver Bowles

THE most important non-metallic mineral industries from a tonnage standpoint are those that are allied with the construction industries and are engaged in handling sand and gravel, crushed stone, building stone, cement, lime and gypsum. The greatest problem facing a number of these industries at this time is over-production. They have experienced un- usual, and in some instances phenomenal, growth during recent years, stinlulated by extensive highway and building construction, but in some localities expansion of producing plants has far outstripped industrial needs. The cement industry is operating at about two- thirds capacity. Over-production tends toward price- cutting and unprofitable and interrupted operation, involving maintenance expenses for idle plants and disorganization of working forces. This condition has encouraged active efforts toward reducing production costs by the introduction of labor-saving equipment. Also, there is a tendency toward the location of manufacturing plants, wherever possible, near the centers of consumption rather than at points of production of raw materials. In order to reduce overhead expense, or for other reasons, many consolidations of companies into larger units have taken place. An economic study of conditions in these industries is highly desirable. The U. S. Bureau of Mines has taken one step forward in this direction in the issuance of Economic Paper 7, entitled "Economics of New Sand and Gravel Developments." Briefly, this report emphasizes the importance of making a thorough study of all the economic factors involved before undertaking new .enterprises.

Jan 1, 1930

By C. Feng

HE sensitivity of twinning in molybdenum alloys containing 20 or more at. pct Re was reported by Dickenson and Richardson&apos; and Sims et a1.&apos; The latter3 also studied the effect of twinning on plastic deformation of these alloys. Recently, in this laboratory, the twinning planes in a series of Mo-Re alloys were successfully identified by tracing their boundaries on two known surfaces of the crystals, with the aid of stereographic projection. The nominal alloy composition and the results of the determination are listed in Table I. Metallic powders of molybdenum and rhenium with 99.9 pct purity were mixed, pressed and arc-melted into buttons under purified argon in a water-cooled copper hearth; the buttons were annealed at 2400 °C in vacuum (10-&apos;mm Hg) for 1 hr, remelted under argon and finally reannealed in vacuum at 2400°C for another hour. This treatment yielded a homogeneous alloy. Large-grain specimens devoid of subgrains were obtained with grain diameter varying from 1/8 to 1/2 in. A typical specimen weighed about 15 g. Orientations were determined by taking X-ray back reflection photographs for each grain on a polished surface of the specimens. Two surfaces were cut and polished; the angle between the two surfaces was measured with an accuracy of *2o. The twins were produced by compression in a hydraulic press at room temperature. Usually, several sets of twins could be obtained within each grain. Except in cases where no twins were formed, (Crystals 7, 8, and 9) the twinning planes were identified consistently as the (112) family over a wide range of alloying compositions and surface orientations of the crystals, as indicated in the stereo-graphic triangle in Fig. 1. The twins, however, were not broad enough to accommodate a conventional X-ray beam and no identification could be made of the twinning direction. Nevertheless, the direction must be one that lies in a plane of symmetry perpendicular to the twinning plane. There are only two such possible planes in a bcc lattice, namely the (110) and the (100) planes. Of these, only the (110) planes are perpendicular to (112), and the <111> direction is the intersection of the two perpendicular planes. It can thus be concluded that <1l1> is the twinning direction. The twinning elements of molybdenum have been reported as the (112) planes and the <111> directions,4 which are also the operative elements in other body-centered-cubic metals, such as W, a-Fe, and ß -brass.5 Thus, the present finding of the twinning elements in Mo- Re alloys supports the concept that twinning formation is mainly governed by the lattice structure. It is of interest to note that for specimens containing 12 at. Pct Re or less, no twins were found after being plastically deformed to as much as 30 pct reduction in height by compression, while for the 35 at. pct Re alloy, twins were formed with less than 1 pct deformation. This, of course, does not exclude the possibilities that for Re-Mo alloys containing 12 pct Re or less, twins could be formed under different conditions, such as at liquid air temperature or under impact loading. The present results, however, suggest that under the same conditions twinning is increasingly sensitive with increasing rhenium content. Consequently, the plastic strain at which twinning starts was found inversely proportional to the amount of rhenium in solid solution with molybdenum. This plastic strain necessary to cause twinning may be used as a criterion in the study of twinning characteristics.

Jan 1, 1961

By S. S. Shen, M. J. Pool, P. J. Spencer, J. R. Guadagno

VERY few thermodynamic data are available for rare-earth alloys, partly because of the difficulties of obtaining the metals in sufficiently pure form and also because of their comparative scarcity up to the present time. The rare earths form a very interesting series in the periodic table in view of the progressive filling of their 4f subvalence electron shell and would be expected to provide useful information with regard to alloying characteristics of transition elements. It has been found in recent calorimetric investigations that the heats of solution of a number of the rare-earth metals in liquid tin are highly exothermic.1-4 Exceptionally strong bonding between rare-earth and tin atoms is clearly indicated in the liquid solutions. Continued thermodynamic studies of the behavior of rare earths in solution could thus contribute a great deal to present theoretical knowledge of alloying behavior and would yield an insight into bonding of a strength hitherto unencountered in liquid alloys. The determination of the heats of solution of the pure components in liquid tin is an essential preliminary to calorimetric work of this nature. Heats of solution of praseodymium, neodymium, and samarium in liquid tin at 750" &apos; and the heats of mixing of Pr-Nd solid solutions&apos; have already been determined in this laboratory. The present investigations with lanthanum continue the study of rare-earth elements. Details of the construction and operation of the liquid metal solution calorimeter used in this work have been published previously by Pool and Peluso and no further description will be given here. The lanthanum used in heat of solution determinations was supplied by Lunex who quoted the purity as 99.9 pct. Their detailed analysis of the material is given in Table I. Samples of 0.0003 to 0.0005 g-atom were used for each run and great care was taken to remove all surface oxide prior to weighing. The samples were stored at all other times in a beaker of oil to prevent their otherwise rapid oxidation. The compounds LaSn (Cudu, L1P type structure) and La&, (structure not classified) were prepared from the appropriate quantities of the two pure components by arc melting under a purified argon atmosphere and once again great precautions were taken to avoid any subsequent oxidation of the specimens. Although no structural examination of the compounds was made, the consistency of thermodynarnic measurements carried out on twenty or so individual samples of each indicates that the compounds were in fact homogeneous, single phase alloys. Samples of the compounds consisting of 0.0003 to 0.002 moles were used in the calorimetric measurements. A solvent bath consisting of approximately 80 g of 99.9 pct pure Sn was used for each series of runs and its heat capacity was determined at regular intervals throughout the experiments using pure tin or tungsten calibration samples. Measurements were made of the heat of solution of lanthanum in liquid tin at 725", 750C, and 775°K and at compositions up to 2.21, 4.76, and 5.25 at. pct La at the three temperatures respectively. In every case, the heat of solution of lanthanum remained constant at its limiting value, within experimental limits, up to the highest lanthanum concentration investigated. Since no change in was observed, it was concluded that the liquid/liquid + LaSn, phase boundary had not been

Jan 1, 1969

By H. R. Stahi

THE ore of the Southeast Missouri lead district consists essentially of galena in dolomitic limestone. The galena usually is in a very finely disseminated condition. The experience of recent years in the concentrating plants of the St. Joseph Lead Co. has shown that dry crushing carried to a point where about 90 per cent of the ore passes a 14-mesh screen liberates the larger portion of the galena, and minimizes further necessary reduction in rod or ball mills. Concentration practice has attempted to carry size reduction to a point where economic unlocking of the galena is obtained, without causing undue sliming of the very friable galena. While 60 per cent of the tonnage of the district is treated by the flotation process, only 40 per cent of the total concentrates is produced by that means, as efforts have always been made to keep the grade and tonnage of flotation feed as low as possible. The milling practice of the district for some years has recognized the generally accepted idea of better selective grinding in rod mills as compared with ball mills, with the attendant decrease in production of fines. The function of rod and ball mills in the various concentrating plants is the grinding of table middlings and coarse tailings that carry lead values too high to be discarded. The simplified flowsheet in Fig. I illustrates the place of grinding mills in the circuit. The arrangement of classifiers, tables and mills constitutes a closed circuit within somewhat flexible limits. In 1937 experiments were conducted in replacing the ball charge in a 6 by 4-ft. ball mill with rods 2 in. in diameter and 51 in. long. This step was taken with some hesitancy, as it was easy to picture a mass of tangled and crossed rods. However, no difficulties developed, and after a short trial period, six more ball mills were converted to rod mills. These mills are of the spur gear and pinion, belt-driven type, using in most cases a 75-hp. motor and having a 9 1/2 -in. open trunnion discharge. As ball mills, they carried a charge of 16,000 to 20,000 lb. of balls, 2 in. in original size. The feed to the mills was dewatered by dewatering wheels and introduced at 70 to 75 per cent solids, with a single scoop feeder. One change in mill design was found advisable when rods were introduced. The existing end liners had an outward flare of 3 ½ in. in 12 in. These were replaced by linings having vertical interior faces, in order to prevent undue end travel of the rods. This change gave an effective working length of 5 2 ¾ in. inside the mill. No alterations were made in the shell liners, which are of the smooth type, made of manganese steel 2 in. in original thickness. The rods at present in use are 51 in. long and 1 3/4in. in diameter. The composition has been varied at times; at present they contain 0.70 per cent carbon and 0.70 per cent manganese. Some breakage and etching occurs as the rods become small, but this is considered preferable to using softer rods, which may kink and cause tangling of the charge. The mill charges are renovated occasionally, broken pieces being removed and the charge brought up

Jan 1, 1945

By N. V. Melnikov, L. N. Marchenko

The latest theoretical and experimental study of physical processes initiated by explosions in solid media have made it possible to obtain a deeper insight into the mechanism of the energy transfer to ambient rock from char es of explosives interspersed with various air gaps. As shown in (17, high explosive action causes excessive fragmentation of medium in the vicinity of the charge, while expansion of the process into the massif is negligible. A theoretical outline of a more rational application of explosion energy was given with a view of obtaining more uniform fragmentation of rock convenient for loading and transportation. The proposed idea proven by experimental study consisted of the possibility of explosion control based on redistribution of explosion energy. Practical realization of the above idea was proposed (1) involving charges with air gaps for rock fragmentation. Since the Rolla Symposium on Mining Research (USA, 1961) (2), borehole charges with air gaps have become common practice. This method of rock blasting is applied in open cast and underground mines working the hardest and viscous, hard, medium hard and soft rocks (ore, quartzites, granites, 1 imes tones, sandstones, coals, etc.) as well as at enterprises for extraction of building materials and raw chemical minerals of any strength. Application of charges with air gaps results in an increase of the degree and uniformity of fragmentation (up to 94 percent of the blasted rock mass consists of fragments not exceeding 400 mm), the average fragment size decreases by 1.5-2 times and the amount of lumps is reduced by 2-10 times (in some cases there are no lumps at all ). Besides, the amount of operation for filling boreholes with tamping material is reduced, the specific consumption of explosives

Jan 1, 1971

By Ronald C. Whiting

SINCE the advent of what has been aptly called "chemical flotation," about 1920, the number and complexity of the various chemicals used in practice have increased enormously. Over 300 patents have been issued dealing exclusively with flotation reagents, and many of these embrace from two or three up to a score or more of specific compounds. The exact number of compounds actually finding a practical use in flotation would be difficult to determine, though the U. S. Bureau of Mines gives an annual list by groups.

Jan 1, 1938

By Louis D. Huntoon

AFTER the completion, in 1905, of the Hammond Mining and Metallurgical Laboratory of the Sheffield Scientific School, Yale University, it became necessary to secure and assay a large assortment of ore-samples, and to arrange the results in such a manner as to admit of use with the least amount of work on the part of the instructor. At first, pulp-samples, together with their respective assays, were secured from the mines, smelters, and public assayers, but this practice did not prove satisfactory. It was not only difficult to secure a sufficiently large supply of material, but it was also impossible to secure the proper assortment required for instructing students. It involved considerable work for the donors to select the samples and furnish a record of the assays, and also for the instructors to examine each pulp and determine its character. Some of the samples did not contain a sufficient quantity of pulp for the student to check his work in case his first assay did not correspond to the record. In order to increase the number of samples and to vary the character of the material, pulp-samples were later mixed with barren rock and with sulphides, but this method also was unsatisfactory and has been discontinued. At present., small lots of ore are secured by gift or purchase from engineers, public assayers, and the managers of mines, mills, and smelters. These lots weigh from 10 to 100 lb. each, and are rarely finer than 0.25 in. in size. The larger samples permit of a careful study by the instructor in order to determine the best method of assaying to be followed. In universities in which assaying is taught the record of the samples should fulfill the following requirements

Nov 1, 1909

By L. H. Levenson, Charles S. Barrett

Numerous determinations1-&apos; of the texture of cold-rolled polycrystalline iron, steel, and ferritic alloys have been made with good agreement among the various observers as to the principal features of the texture common to all, but there has been no adequate explanation of the texture in terms of, the behavior of individual grains. This study presents an explanation of the texture based on the observed rotation of single crystals when deformed in a manner similar to a grain in the aggregate, a method we have found useful in leading to a better understanding of compression and tension textures;8,9,10 in particular, the aim has been to determine experimentally the end orientations of rolled single crystals of iron. These are discussed in connection with the point of view of Weverl and of Boas and Schmid2 that the rolling texture is a simple compression texture (compression normal to the rolling plane) superimposed on a simple tension texture (tension in the rolling direction), and the point of view of Kurdjumow and Sachs3 that three ideal end orientations exist. Experimental Method The single crystals used were in the form of disks cut from a stock of crystalst pre- pared in this laboratory by a strain-anneal method from mild steel decarburized and purified in hydrogen, the details of which have been described elsewhere.11 To ensure maximum elongation in the rolling direction and to simulate approximately the rolling of a grain in an aggregate, lateral flow was constrained by placing each crystal in a close-fitting hole in a plate of copper or iron of equal thickness and rolling the plate and crystal together. About one-third of the crystals were rolled in a "sandwich" pack by adding top and bottom cover plates. The two-high mill used had 8-in. diameter rolls and was operated at 15 r.p.m. The initial diameter of the crystals was between 1/4 and 1/2 in., while the starting thickness varied from 0.031 to 0.376 in. With a single exception, which was rolled 63 per cent, the crystals were rolled to a final reduction in thickness of 82 to 97 per cent in 20 to 40 passes, alternately changing the sense of the rolling direction. The initial orientations of the crystals were determined either by X-ray back reflection12 or by optical reflectionl3 from etch pits; the mean final orientations were determined by X-ray Laue photograms using molybdenum, silver, or tungsten radiations, by optical reflection, and in many cases by both methods. Results Twenty-six crystals were studied. It was found that there were three typical be-

Jan 1, 1941

By Gerald A. Munson, Fremont F. Clarke

DURING recent years the use of lithium has expanded greatly in industrial, chemical, and metallurgical fields, while at the same time modernized methods of mining and refining lithium have increased production. Technical literature includes many papers describing the geology and mineralogy of lithium deposits. Mining and beneficiating problems, however, have not been thoroughly described. Published reports have failed to emphasize that one of the chief reasons lithium minerals were not extensively mined until recently is the difficulty of beneficiation. Four lithium minerals of pegmatites and the lithium-sodium-phosphate byproduct from the brines at Searles Lake, Calif., have been sources of lithium. Among the pegmatite minerals, only spodu-mene and petaline are known to occur in deposits large enough to support large tonnage operations. Spodumene, a lithium-aluminum-silicate, is the principal lithium mineral mined in the U. S. Lithium Corp. of America, during its rapid development and growth, has successfully employed three different methods of concentration: 1) hand sorting, 2) Heavy Media separation, and 3) froth flotation. Each method, though economic in its sphere, is becoming outdated as extractive techniques improve. The most recent development has taken place at Lithium Corp.&apos;s new operation in North Carolina, where the extractive process yields lithium compounds directly from mined rock without an intervening concentrating step. Until 1954 Lithium Corp. mined only in the southern part of the Black Hills of South Dakota, where the various types of lithium-bearing pegmatite could be used to develop untried processes of beneficiation. Concentrates from these operations are shipped to the corporation&apos;s chemical plant in St. Louis Park, Minn., where actual extraction of lithium and production of commercial compounds takes place. Nature of Deposits The geology of the southern Black Hills pegmatite deposits is admirably presented by a U. S. Geological Survey publication.&apos; Only the factors pertinent to exploitation need be mentioned here. Lithium Corp. has been interested primarily in three deposits, the Edison, the Mateen, and the Longview-Beecher No. 2. The history of these deposits dates back to the mining boom of 1880 to 1900 in the Black Hills, when most of the deposits were prospected for tin by the ill-fated Harney Peak Tin Mining Co. The three deposits described here, however, lay idle and unwanted until Lithium Corp. opened the Edison mine in 1943 and the Mateen and Longview-Beecher No. 2 in 1951. Edison Deposit: The Edison deposit is about a mile southeast of Keystone, S. D., on the northeastern flank of the Harney Peak uplift. The deposit consists of no less than four and probably at least six separate pegmatites that coalesce in a central mass from which the individual pegmatites finger outward and downward in complexly folded schist and gneiss beds of the country rock.

Jan 1, 1956