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By Waldemar Lindgren

Fifteen years ago, in his presidential address before the Washington Academy of Sciences,' Alfred H. Brooks said: "Applied geology can only maintain its present high position by continuing the researches which advance the knowledge of basic principles. Future progress in applied geology depends on progress in pure geology. Early in 1927, Dr. David White, then chairman of the Division of Geology and Geography of the National Research Council, appointed a committee "On the Processes of Ore Deposition," which was the first recognition by the Council of this branch of applied geology. This committee will not be able to solve the many complex problems involved; it can only clear the way, survey the field, state the problems and encourage systematic research. This short paper aims to outline and to analyze the present status of this kind of geological research, to ascertain the quality of the work and to suggest lines that might profitably be followed. Increasing Demand for Geologists Economic geology, or the art of geology, could develop only after the principles of geology and mineralogy had been established. Before that time it was merely a collection of trade rules accompanied by more or less wild speculations. Thus we observe the beginnings of economic geology in the period 1770-1820. Soon afterwards, the State Surveys were established in this country, with the realization that the natural resources should be investigated and described. Geology was hardly yet equal to the task of scientific research in relationships and genesis, however, and there followed a period of discouragement and stagnation. In the meanwhile, pure geology had again registered progress, and, based on its principles and also on the rapid mining development in the Cordilleran region, the present phase of the study of ore deposits began to take form. Raphael Pumpelly, S. F. Emmons and G. F. Becker were among the pioneers in this movement. The United States Geological Survey was organized. Ore deposits were scientifically described and studied along lines of structure and mineralogy; theories of genesis were advanced, not always permanent but based on sound induction.

Jan 1, 1928

By C. P. Proctor, J. B. Morrow

With numerous plans under consideration for coal classification, and with the advent of the Bituminous Coal Code, the intelligent sampling of coal has become increasingly important. To us it is rather significant that there have been very few fundamental studies of coal sampling in American technical literature since those of E. G. Bailey, which appeared in the Journal of Industrial and Engineering Chemistry in March, 1909. He covered the subject up to that time so thoroughly and in such an excellent manner that perhaps many other later students have felt that they could add very little to his findings. The recent studies of the British Engineering Standards Association have indicated the possibility of a somewhat different interpretation of Bailey's results, permitting the taking of smaller samples, and perhaps it will now be helpful to reopen this question. C. W. H. Holmes, in an informative series of articles on coal sampling recently published in Colliery Engineering, makes two rather interesting statements, as follows: It is scarcely surprising to find a lack of interest and knowledge regarding the sampling of coal not only in the mining industry itself but also among consumers of industrial fuel: at its best coal sampling is a dirty business, regarded as a nuisance and an expense by the commercial man, and usually as a nuisance and nothing else by the chemist. The writer can conceive only two classes of people who have never experienced any difficulty in obtaining representative samples of coal from wagons; those who have never tried to, and those who have never had the necessity or desire to check the accuracy of their work. The primary purpose of this paper is to present some tabulated data of the more significant results of a sampling investigation undertaken during the last four years to obtain certain fundamental data on the variables connected with coal sampling and to point out that often assumptions have been made that are not in accordance with the facts. One of the standard sampling methods states:

Jan 1, 1936

By C. P. Proctor, J. B. Morrow

With numerous plans under consideration for coal classification, and with the advent of the Bituminous Coal Code, the intelligent sampling of coal has become increasingly important. To us it is rather significant that there have been very few fundamental studies of coal sampling in American technical literature since those of E. G. Bailey, which appeared in the Journal of Industrial and Engineering Chemistry in March, 1909. He covered the subject up to that time so thoroughly and in such an excellent manner that perhaps many other later students have felt that they could add very little to his findings. The recent studies of the British Engineering Standards Association have indicated the possibility of a somewhat different interpretation of Bailey's results, permitting the taking of smaller samples, and perhaps it will now be helpful to reopen this question. C. W. H. Holmes, in an informative series of articles on coal sampling recently published in Colliery Engineering, makes two rather interesting statements, as follows: It is scarcely surprising to find a lack of interest and knowledge regarding the sampling of coal not only in the mining industry itself but also among consumers of industrial fuel: at its best coal sampling is a dirty business, regarded as a nuisance and an expense by the commercial man, and usually as a nuisance and nothing else by the chemist. The writer can conceive only two classes of people who have never experienced any difficulty in obtaining representative samples of coal from wagons; those who have never tried to, and those who have never had the necessity or desire to check the accuracy of their work. The primary purpose of this paper is to present some tabulated data of the more significant results of a sampling investigation undertaken during the last four years to obtain certain fundamental data on the variables connected with coal sampling and to point out that often assumptions have been made that are not in accordance with the facts. One of the standard sampling methods states:

Jan 1, 1936

By E. L. Spain

The deposits described in this paper occur over much of Wayne County and in the southeast portion of Hardin County, Tennessee, and in the northeast and northwest portions of Mississippi and Alabama respectively. The presence of tripoli in this region has been known for some time and descriptions of various occurrences in Tennessee have been made by Jewelll and Miser2, while Hilgard3, Lowe4 and Logan5 have treated the deposits that occur in the adjacent portions of Alabama and Mississippi, but there has not been a 'general survey of the entire field summarizing completely the geology of the deposits with respect to their origin and stratigraphic relationships. During 1934, while engaged in surveys of mineral resources through this region for the Tennessee Valley Authority, the writer collected data with this in mind, and has assembled them in this report. He is indebted to H. S. Rankin and N. A. Rose, of the Tennessee Valley Authority Geology Division, for field assistance. Location of Tripoli Deposits Fig. 1 shows the locations of deposits of tripoli in a long belt that extends from northeast Wayne County southwestward into northwest Alabama and thence passes into Mississippi, where the formations carrying it are finally covered by Cretaceous sand and gravel of the Mississippian Embayment. Occasional deposits occur also in the southeastern corner of Hardin County, Tennessee. While tripoli is found at nearly all points along this axis where the related formations are exposed, the largest deposits are grouped about three different centers. Waynesboro-Collinwood District.—In the area between Waynesboro and Collinwood, in Wayne County, Tennessee, tripoli of various grades outcrops in the valley of Green River and in tributary valleys on either side. This district is roughly 12 miles long in a northeast-southwest direction and has a maximum width of 5 miles at its northern end. Exposures are found in road cuts, highway chert pits, in the beds of some of the streams, and on hillsides. The greatest number of high-grade

Jan 1, 1938

By E. L. Spain

The deposits described in this paper occur over much of Wayne County and in the southeast portion of Hardin County, Tennessee, and in the northeast and northwest portions of Mississippi and Alabama respectively. The presence of tripoli in this region has been known for some time and descriptions of various occurrences in Tennessee have been made by Jewelll and Miser2, while Hilgard3, Lowe4 and Logan5 have treated the deposits that occur in the adjacent portions of Alabama and Mississippi, but there has not been a 'general survey of the entire field summarizing completely the geology of the deposits with respect to their origin and stratigraphic relationships. During 1934, while engaged in surveys of mineral resources through this region for the Tennessee Valley Authority, the writer collected data with this in mind, and has assembled them in this report. He is indebted to H. S. Rankin and N. A. Rose, of the Tennessee Valley Authority Geology Division, for field assistance. Location of Tripoli Deposits Fig. 1 shows the locations of deposits of tripoli in a long belt that extends from northeast Wayne County southwestward into northwest Alabama and thence passes into Mississippi, where the formations carrying it are finally covered by Cretaceous sand and gravel of the Mississippian Embayment. Occasional deposits occur also in the southeastern corner of Hardin County, Tennessee. While tripoli is found at nearly all points along this axis where the related formations are exposed, the largest deposits are grouped about three different centers. Waynesboro-Collinwood District.—In the area between Waynesboro and Collinwood, in Wayne County, Tennessee, tripoli of various grades outcrops in the valley of Green River and in tributary valleys on either side. This district is roughly 12 miles long in a northeast-southwest direction and has a maximum width of 5 miles at its northern end. Exposures are found in road cuts, highway chert pits, in the beds of some of the streams, and on hillsides. The greatest number of high-grade

Jan 1, 1938

By R. W. Raymond

(Pittsburg Meeting, March,1910.) THE Giroux Consolidated Mines Co. is equipping a five-compartment shaft at Kimberly, Nev., which will serve the Alpha mice. The depth of this shaft, January, 1910, is 963 ft., and of this depth 948 ft. was opened by raising, 15 ft. of sinking was done so that the bearers, collar-set, and three shaft-sets might be installed and concreted, and with this done it was possible to erect the necessary surface-equipment for resuming shaft-timbering on the completion of the raise. The arrangement of the shaft-timbering is shown in Fig. 1. At the 1,000-ft. level of the Alpha, and 750 ft. SW. from the Alpha shaft, a 14- by 18-ft. station was cut, and a 25-h-p. air-hoist *as installed. From here the raising commenced on July 5, 1909. The raise was cut approximately 13 by 21. ft. in area, and supported by timbering with square sets, illustrated in Fig. 2, which shows the division into four compartments. The end compartments, which were used as chutes, had the center girts heavier than in the others on account of the wear from falling rock. The chute-lining was braced by inserting 8- by 8-in. stiffeners parallel to and half way between successive caps. Similarly, the lagging on the wall sides of the cage-way and the compartment for pipes and ladder was stiffened with 4- by 6-in. timbers. In the pipe-and-ladder compartment the chute-stiffeners were reinforced with 8- by 8-in, struts, and as the cage-way was partitioned off by braced lining, there was practically no chance of rock entering the ladder-way in case a chute burst into the cage-way. Over the two center compartments the last two, sets were always bulkheaded with 8- by 12-in. timbers, shown in Fig. 3, and from the lower bulkhead the cage sheave-wheel was suspended. After a round of holes had been blasted and the loose

Jun 1, 1910

By Boyd Dudley

The material presented in this paper is an abstract of a thesis submitted by the writer to the faculty of the Massachusetts Institute of Technology, as part requirement for the degree of Master of Science. The investigation was undertaken at the suggestion of Prof. H. 0. Hofman, and it was conducted, under his direction, in the laboratories of the Mining Department of the Institute. The purpose of the work was, first, to study some of the reactions that have been considered as a part of the mechanism of the chloridiz-ing roast, and second, to study the conditions under which nickel oxide and copper oxide may be chloridized. While the production of chlorine gas by various reactions during the chloridizing roast may not be primarily useful in the chloridation of metal oxides and compounds, it nevertheless serves a useful purpose in preventing the dissociation and decomposition of chlorides once they have been formed; for example, the dissociation of cupric chloride into cuprous chloride and chlorine. Therefore it was thought that a study of some chlorine-producing reactions would prove of interest, and the first series of experiments dealt with this phase of the subject. he object of the latter part of the work was to show the possibility of treating heavy sulphide ores, such as those of Sudbury, Ontario, containing much iron and small amounts of copper and nickel, by chloridizing and removing the copper, leaving an iron-nickel oxide product suitable for smelting in the blast furnace for nickel-bearing pig iron. The chloridizing of the copper would, of course, be preceded by a roast for the removal of sulphur, the sulphur oxides being available for the manufacture of sulphuric acid, if under the local conditions this product would be of commercial value. Reactions of the Chloridizing Roast Reaction of Sodium Chloride, Sulphur Trioxide, and Oxygen.—The first reaction studied was that involving the production of chlorine

Jan 1, 1915

By C. A. Heiland

The new geophone described herein was developed by Charles H. Hull, instrumentmaker of the Colorado School of Mines, and the writer. The first geophone was invented during the war for the purpose of detecting enemy sapping or underground mining operations and for locating enemy artillery. It is based on the principle of the seismograph—a heavy lead mass suspended by one or two diaphragms, which are clamped to an air-tight case. When the ground vibrates during the transmission of sound waves, the case moves with it while the so-called steady mass remains practically motionless. Attached to the top of the casing is a hose leading to an earpiece shaped like a stethoscope. When the mass and the diaphragm move up and down in the case, the air is compressed and rarified in the inside; thus the vibration is communicated as sound wave to the human ear. The geophone combines a surprising simplicity of construction with an extreme sensitivity. Other listening instruments were developed during the war, adaptations of the telephone and the microphone—that is, instruments operating through the medium of electricity—of which the so-called seismicrophone, an adaptation of the carbon-granule microphone receiver, probably has found the greatest application, but such instruments apparently have not proved as useful as the simple geophone despite obvious advantages arising from the use of electricity. The carbon receivers were more subject to extraneous noises and to what is called "frying," and they did not offer the advantage possessed by the geophone; namely, the simultaneous use of two receivers, which makes it possible to determine the location of the source of sound. During the war, the U. S. Bureau of Mines made a study of the geophone and of the propagation of sound waves through rock. These studies have been continued, as the earlier results proved the possibility of using the geophone in various non-military ways, principally in mining, and the results of these studies have been published.'

Jan 1, 1932

By Vsevolod Krivobok

IT is generally recognized that "low temperatures" have a definite effect on the properties of metals and alloys. Furthermore, it is also generally understood that the effect is decidedly adverse. The possibility that the same low-temperature treatment might be employed for the purpose of improving certain properties of the .alloys has received less attention until recently, and the experimental and theoretical knowledge consequently is meager. The effect of low temperatures may be studied in two ways: by studying such properties as tensile strength, hardness, impact resistance, etc., at low temperature, and by studying the properties of alloys at room temperature after these alloys have been subjected to a low-temperature treatment. Even in the latter case, certain properties will differ materially from the same properties obtained on identical material but without cold treatment. In other words, subjecting alloys to cold treatment results in an irreversible change in mechanical properties. Changes of this character are usually indications of the appearance of a new phase or phases, and would be likely to occur in alloys which, either by virtue of their composition or by heat treatment, are retained at room temperature in a metastable condition. Consequently, studies of the effect of low temperatures logically should be conducted from the physicochemical point of view, since the results of such studies not only would furnish metallurgists with interesting theoretical data but would clearly indicate the classes of alloys that would hold promise of improvement, and, possibly, of new applications. As the present investigation deals with chromium and chromium-nickel alloys of iron of the stainless variety, it has been thought desirable to present the data concerning low-temperature properties of these alloys, available from the most recent and most comprehensive work of H: S. Russell.' A summary, of these data is given in Table 1. The data are confined to a limited number of alloys of the type dealt with in the present

Jan 1, 1931

By Linn Bradley

F. H. WILLCOX, Pittsburgh, Pa. (communication to the Secretary*). -We must keep in mind, in balancing the savings-to be anticipated by the most efficient combustion of gas, the best heat absorption by stoves or boilers, and by heat conservation of the thermal equivalent carried in. blast-furnace gas-against the cost in operation, maintenance, depreciation and interest charges of the equipment required to realize the savings, that in boilers and hot-blast stoves we are basing our economies upon two different, combustion phenomena. In a boiler, evaporating water at a heat efficiency of 70 per cent., approximately 47,550 B.t.u. is consumed per boiler horsepower. Taking the blast, furnace gas cited in the above paper, we are using about 38 ¾ lb. of cold-washed gas per boiler horsepower. Using the hot-cleaned gas, the same equivalent heat is furnished by 34 1b. of the gas , This leaves of the 38 ¾ lb. required in the case of cold-washed gas, 4 ¾ lb. or 6,650 B.t.u. available for raising more steam when dry-hot gas is used, which means that an equivalent amount of coal firing can be dispensed with. Per ton of iron, this figure 2/3 X 12,000/38.75 X 4.75 = 980 lb. gas or 1,372,000 B.t.u. or 100 lb. coal. At $1.50 per ton of coal, the net saving per ton of pig iron produced by the use of dry-hot over wet-cold cleaning will, therefore, be about $0.06 2/3. At a stove heating 8,500 lb. of air per toil iron from 150° F., one-quarter of the dry-hot cleaned gas, or 3,000 lb., would heat the air to 1,450° F. 3,000 X 1,400 X 0.70 = (8,500 X 0.255) = 1,300. The cold-wet gas would heat the same amount of air to 1,280° F. 3,000 X 1,225 X 0.70 = (8,500 X.0.255) = 1,130.

Jan 4, 1917

By Ian Wark

SODIUM sulfide is used extensively to increase the recovery of oxidized copper and lead minerals by flotation, particularly when using xanthates as collectors. It is generally assumed that the sodium sulfide converts a film of the oxidized mineral to the sulfide, and that the xanthate, while not a very effective collector for the oxidized minerals, is a good collector for the sulfide. On the other hand, Taggart and his collaborators' claim that unless sulfide minerals are oxidized they cannot adsorb xanthates and do not float. Gaudin2 states that amyl xanthate, used in conjunction with sodium sulfide, gives better results than ethyl xanthate. Rabone3 and Mayer-Schranz4 agree that excess of sulfide functions as a depressant. Owing to the greater solubilities of the oxidized minerals than of the sulfides, the consumption of sodium sulfide is greater than that of most other flotation reagents, up to 10 lb. per ton of ore being used in some plants. Luyken and Bierbrauer5 recommend a water washing to remove soluble heavy metal salts; by this means sulfide consumption may be reduced. It was desirable to determine the limits of the sulfide concentrations between which contact is possible at surfaces of anglesite and cerussite in xanthate solutions. Similar determinations were desirable for the sulfide minerals with which the oxidized minerals are usually associated, since conditions should be chosen, if possible, so that the two types of mineral will float together. Because of the formation, especially in acid solutions, of hydrogen sulfide and of the hydrosulfide ion (HS-), the permissible limits of sulfide addition are obviously dependent upon the pH value. Sphalerite responds to ethyl xanthate only in the presence of an activator; for example, copper sulfate. It was necessary, therefore, to determine whether sodium sulfide interferes with the activation of sphalerite by copper sulfate. The combined effect of sulfide and copper sulfate was determined also for galena, chalcopyrite and pyrite.

Jan 1, 1936

By R. P. Marshall

This note describes positive evidence that hydrogen in titanium alloys diffuses under the influence of a thermal gradient. The experiments confirmed the expected similarity of this system to the H-Zr system and produced qualitative information on the magnitude of the heat of transport for hydrogen in titanium alloys. This effect has practical importance in applications where titanium alloys operate in a thermal gradient under conditions such that hydrogen embrittlement may develop within the expected lifetime of the structure, for example in supersonic aircraft service. The theories of thermal-gradient diffusion may be found in recent reviews and experimentation in this field by Shewmon,1 Sawatzky,2 Markowitz,3 and Darken and Oriani.4 The basis for Soret thermal diffusion is the "heat of transport", denoted by Q*. This is an energy term for the amount of heat (energy) transferred by atomic diffusion, and can be either positive or negative signifying a driving force for atomic diffusion to the cooler or hotter region, respectively. Experimentally, Q* is determined by plotting the natural logarithm of the point-to-point concentrations after exposure to a thermal gradient vs the respective point-to-point temperatures in units of the inverse absolute temperature scale. The slope of the straight line is Q*/R, R being the gas constant. For the titanium experiments, specimens (3 by 1 by 1/16 in.) of a) commercially pure titanium, b) the 8 Al-1 Mo-1 V titanium alloy, and c) the 6 A1-4 V titanium alloy were exposed to thermal gradients of 6° to 115°C per in. for 18 days at 250° to 550°C. The temperature gradient was in the direction of the 3-in. dimension. The hydrogen concentrations existing after exposure were determined on sections of the specimens by vacuum extraction. Three sections of unexposed sheet of each alloy were analyzed as standards to allow a check for hydrogen

Jan 1, 1965

By R. Ellerman

The hydrometallurgical processing of an impure zinc oxide fume is described. Flowsheet includes roasting for fluorine elimination and countercurrent leaching to produce a neutral sulphate solution. This solution is combined with zinc sulphide leach solution for subsequent purification and electrolysis. Novel to the neutral leach step is the use of automatic pH control. THE electrolytic zinc plant of the Hudson Bay Mining and Smelting Co. Ltd. was erected in 1929-1930 to process zinc sulphide concentrates produced from ore mined at Flin Flon, Manitoba. Since 1930, production of high purity slab zinc has been continuous. In May 1951, construction of a fuming plant was completed and operations were started to recover zinc from copper smelter reverberatory slag. A second zinc-bearing material in the form of an impure zinc oxide fume was then made available for treatment. Coincident with the construction of the fuming plant, additions were made to the electrolytic zinc plant to recover the zinc in the fume as slab metal. The original plant capacity of 70 tons of slab zinc per day was steadily increased up to May 1951, at which time the daily production averaged 130 tons. With the advent of the fuming plant and the processing of zinc oxide fume, production was stepped up to the present capacity of 190 tons per day. Of this, approximately 48 pct is contributed by the processing of zinc oxide fume. This additional source of raw material has allowed a 20 pct cutback in mining and milling operations, thereby adding considerably to the life of the Flin Flon mine. Zinc sulphide concentrates are treated by the usual hydrometallurgical method. Details of this operation and plant were described by Carr and Reikie in 1935' and Kent in 1951.8 The impure fume is treated in two operations. First, it is roasted to eliminate fluorine. Next, it is subjected to a countercurrent leach with spent electrolyte to extract the zinc as a neutral zinc sulphate solution. During this leaching step, soluble impur-

Jan 1, 1956

By B. Tani, K. Anderson, I. Johnson, R. Schablaske

INVESTIGATION of the various rare earth-cadmium binary systems discloses the existence of a compound corresponding to the composition MCd6 in all systems save the La-Cd system. Lattice constants for all of the MCde compounds, except LaCd6 which apparently does not form, and PmCd6 whose synthesis was not attempted, are also recorded herein. Iandelli and Ferro 1 report the existence of the compound CeCd6. No additional information, structural details, and so forth are given. Elliott and Lemons2,3' have measured the vapor pressure of cadmium over CeCd6 and have calculated the activity of cadmium in solid CeCd6. These authors find that CeCd6 exists over a composition range from 5.967 to 6.098 (Cd:Ce ratio) at 584oC, and from 5.971 to 6.118 at 639°C. The following is an excerpt from the paper by Elliott and Lemons: 2 "Recently Mr. F. H. Ellinger of this laboratory has indexed an X-ray diffraction powder pattern of CeCd6.00 which we had prepared by gas phase reaction. The compound has a primitive cubic unit cell with a = 15.783 + 0.001A Based on the volume of the cubes surrounding an elemental cerium or an elemental cadmium atom, Mr. Ellinger finds room for 24.10 CeCd6 formula units in the CeCd6 unit cell; similar calculations based on CeCd2 and CeCd11 yield 24.18 formula units per unit cell. The presence of 24 CeCd6 units per unit cell seems probable with an X-ray density of 8.255 grams per cubic centimeter. The most one can say about in-terstitial~ is that there appears to be room in the crystal even at room temperature." Measurements of the solubility of the rare earths in liquid cadmium4 led to the discovery of GdCd6,

Jan 1, 1964

By Maxwell Gensamer, Vsevolod N. Krivobok

It is generally recognized that "low temperatures" have a definite effect on the properties of metals and alloys. Furthermore, it is also generally understood that the effect is decidedly adverse. The possibility that the same low-temperature treatment might be employed for the purpose of improving certain properties of the alloys has received less attention until recently, and the experimental and theoretical knowledge consequently is meager. The effect of low temperatures may be studied in two ways: by studying such properties as tensile strength, hardpess, impact resistance, etc., at low temperature, and by studying the properties of alloys at room temperature after these alloys have been subjected to a low-temperature treatment. Even in the latter case, certain properties will differ materially from the same properties obtained on identical material but without cold treatment. In other words, subjecting alloys to cold treatment results in an irreversible change in mechanical properties. Changes of this character are usually indications of the appearance of a new phase or phases, and would be likely to occur in alloys which, either by virtue of their composition or by heat treatment, are retained at room temperature in a metastable condition. Consequently, studies of the effect of low temperatures logically should be conducted from the physicochemical point of view, since the results of such studies not only would furnish metallurgists with interesting theoretical data but would clearly indicate the classes of alloys that would hold promise of improvement, and, possibly, of new applications. As the present investmigation deals with chromium and chromium-nickel alloys of iron of the stainless variety, it has been thought desirable to present the data concerning low-temperature properties of these alloys, available from the most recent and most comprehensive work of H. S. Russell.l A summary of these data is given in Table 1. The data are confined to a limited number of alloys of the type dealt with in the present

Jan 1, 1931

By Albert F. J. Bordeaux

Discussion of the paper of Albert F. J. Bordeaux (Bi-Monthly Bulletin, No. 23, September, 190S, pp. 629 to 640). A. H. BROMLY, Zihuatanejo, Guerrero, Mexico (communication to the Secretary*) :-The following criticism of what "is offered as a summary which may be found useful by mining engineers," is not dictated by any captious spirit, but in the interest of historical and scientific accuracy. The States of Queretaro and Oaxaca have produced sufficient silver to warrant more extended notice. Referring to Pachuca, State of Hidalgo, the somewhat loose and. inexact statement is made that "the ore-deposit is an andesite, intermixed with quartz-veins, rich from the surface." A better description would be,-the ore-deposits consist of quartz-veins in andesite. It is notable that many of the rich shoots worked in recent days did not come to surface. In consequence, Pachuca, is often quoted by the ill-informed as a camp in which values improve with depth, the truth being that the veins carry shoots, or clavos, some of which were exposed at surface and some not. The name of " electric plow," applied to the mechanical stirrer of recent use, is certainly not to be recommended. The stirrer, or agitator, consists essentially of a traversing gang-plow, operated by power through shafting, drums, and wire-rope. The fact that in certain plants the motive-power used is electricity does not make it an electric plow. Such a name suggests a machine of which the motor is an essential and integral part; which is not so in this case. A lathe in a factory driven by water-power is not called a hydraulic lathe. My experience agrees with Dr. Raymond's note as to azulaque, which in sortie districts is also applied to blue copper carbonate. The El Oro, Esperanza, and Mexico mines should be allocated to the State of Mexico; the Dos Estrellas being in Michoacan, as stated. The El Oro quartz certainly does not appeal to me

May 1, 1909

By Brahm Prakash, R. Schuhmann

Chemical conditions for flotation and nonflotation of cassiterite and fluorite with oleic acid as collector and with alizarin dyes as modifying agents were studied by means of small-scale, vacuum-flotation tests. Artificial cassiterite was prepared fot these tests by high-temperature methods, especially by crystallization from borax melts. FLOTATION test work on Bolivian tin ores some years ago led to the development of several workable schemes of selective soap flotation, but left unanswered many questions of soap-flotation chemistry.' Accordingly, the study of the activation and soap flotation of quartz just reported? was undertaken as a start toward the elucidation of some of the unanswered questions. The experimental work on quartz flotation consisted primarily of small-scale, vacuum-flotation tests in which activator and collector additions and pH were varied between wide limits. In the work to be described in this paper, the soap flotation of cassiterite and fluorite was studied by the vacuum-flotation technique developed in the previous study of quartz. Using oleic acid as collector, conditions for floating cassiterite and fluorite in the absence of modifying agents were first determined. Then the effects of barium, calcium, and alizarin dyes on the flotation of cassiterite, fluorite, and quartz were studied. Alizarin dyes were chosen for study because of the promise they have shown as selective modifying agents in the flotation of non-sulphide minerals.12,1 Also, they form a family of reagents in which there should be a systematic correlation of chemical properties with composition. As a preliminary to the study of cassiterite flotation, an investigation of the preparation of synthetic cassiterite and X ray studies of natural and synthetic cassiterite were undertaken. Experimental Methods The flotation technique and most of the reagent preparations were described fully in the previous paper.' In addition, for the present work it was necessary to prepare satisfactory stocks of clean cassiterite and fluorite and to obtain samples of alizarin dyes. Cassiterite: High-grade cassiterite from the Netherlands East Indies was crushed, sized, and cleaned

Jan 1, 1951

By Brahm Prakash, R. Schuhmann

Chemical conditions for flotation and nonflotation of cassiterite and fluorite with oleic acid as collector and with alizarin dyes as modifying agents were studied by means of small-scale, vacuum-flotation tests. Artificial cassiterite was prepared fot these tests by high-temperature methods, especially by crystallization from borax melts. FLOTATION test work on Bolivian tin ores some years ago led to the development of several workable schemes of selective soap flotation, but left unanswered many questions of soap-flotation chemistry.' Accordingly, the study of the activation and soap flotation of quartz just reported? was undertaken as a start toward the elucidation of some of the unanswered questions. The experimental work on quartz flotation consisted primarily of small-scale, vacuum-flotation tests in which activator and collector additions and pH were varied between wide limits. In the work to be described in this paper, the soap flotation of cassiterite and fluorite was studied by the vacuum-flotation technique developed in the previous study of quartz. Using oleic acid as collector, conditions for floating cassiterite and fluorite in the absence of modifying agents were first determined. Then the effects of barium, calcium, and alizarin dyes on the flotation of cassiterite, fluorite, and quartz were studied. Alizarin dyes were chosen for study because of the promise they have shown as selective modifying agents in the flotation of non-sulphide minerals.12,1 Also, they form a family of reagents in which there should be a systematic correlation of chemical properties with composition. As a preliminary to the study of cassiterite flotation, an investigation of the preparation of synthetic cassiterite and X ray studies of natural and synthetic cassiterite were undertaken. Experimental Methods The flotation technique and most of the reagent preparations were described fully in the previous paper.' In addition, for the present work it was necessary to prepare satisfactory stocks of clean cassiterite and fluorite and to obtain samples of alizarin dyes. Cassiterite: High-grade cassiterite from the Netherlands East Indies was crushed, sized, and cleaned

Jan 1, 1951

By Alwyn Birchmore Cox, Ian William Wark

Sodium sulfide is used extensively to increase the recovery of oxidized copper and lead minerals by flotation, particularly when using xanthates as collectors. It is generally assumed that the sodium sulfide converts a film of the oxidized mineral to the sulfide, and that the xanthate, while not a very effective collector for the oxidized minerals, is a good collector for the sulfide. On the other hand, Taggart and his collaborators1 claim that unless sulfide minerals are oxidized they cannot adsorb xanthates and do not float. Gaudin2 states that amyl xanthate, used in conjunction with sodium sulfide, gives better results than ethyl xanthate. Rabone3 and Mayer-Schranz4 agree that excess of sulfide functions as a depressant. Owing to the greater solubilities of the oxidized minerals than of the sulfides, the consumption of sodium sulfide is greater than that of most other flotation reagents, up to 10 lb. per ton of ore being used in some plants. Luyken and Bierbrauer5 recommend a water washing to remove soluble heavy metal salts; by this means sulfide consumption may be reduced. It was desirable to determine the limits of the sulfide concentrations between which contact is possible at surfaces of anglesite and cerussite in xanthate solutions. Similar determinations were desirable for the sulfide minerals with which the oxidized minerals are usually associated, since conditions should be chosen, if possible, so that the two types of mineral will float together. Because of the formation, especially in acid solutions, of hydrogen sulfide and of the hydrosulfide ion (HS-), the permissible limits of sulfide addition are obviously dependent upon the pH value. Sphalerite responds to ethyl xanthate only in the presence of an activator; for example, copper sulfate. It was necessary, therefore, to determine whether sodium sulfide interferes with the activation of sphalerite by copper sulfate. The combined effect of sulfide and copper sulfate was determined also for galena, chalcopyrite and pyrite.

Jan 1, 1939

By Ian William Wark, Alwyn Birchmore Cox

Sodium sulfide is used extensively to increase the recovery of oxidized copper and lead minerals by flotation, particularly when using xanthates as collectors. It is generally assumed that the sodium sulfide converts a film of the oxidized mineral to the sulfide, and that the xanthate, while not a very effective collector for the oxidized minerals, is a good collector for the sulfide. On the other hand, Taggart and his collaborators1 claim that unless sulfide minerals are oxidized they cannot adsorb xanthates and do not float. Gaudin2 states that amyl xanthate, used in conjunction with sodium sulfide, gives better results than ethyl xanthate. Rabone3 and Mayer-Schranz4 agree that excess of sulfide functions as a depressant. Owing to the greater solubilities of the oxidized minerals than of the sulfides, the consumption of sodium sulfide is greater than that of most other flotation reagents, up to 10 lb. per ton of ore being used in some plants. Luyken and Bierbrauer5 recommend a water washing to remove soluble heavy metal salts; by this means sulfide consumption may be reduced. It was desirable to determine the limits of the sulfide concentrations between which contact is possible at surfaces of anglesite and cerussite in xanthate solutions. Similar determinations were desirable for the sulfide minerals with which the oxidized minerals are usually associated, since conditions should be chosen, if possible, so that the two types of mineral will float together. Because of the formation, especially in acid solutions, of hydrogen sulfide and of the hydrosulfide ion (HS-), the permissible limits of sulfide addition are obviously dependent upon the pH value. Sphalerite responds to ethyl xanthate only in the presence of an activator; for example, copper sulfate. It was necessary, therefore, to determine whether sodium sulfide interferes with the activation of sphalerite by copper sulfate. The combined effect of sulfide and copper sulfate was determined also for galena, chalcopyrite and pyrite.

Jan 1, 1939