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By R. L. Perrine

This paper shows how stability theory can be used to optimize solvent recovery of oil. Application of the theory leads to definition of the limiting conditions required for stable displacement to occur. One of these conditions is that the size of a solvent "slug" must at least equal a prescribed minimum. The criteria to be satisfied are miscibil-ity and stability. Stability implies that no viscous fingering will occur and that mixing will be caused only by a dispersion process. Miscibility implies that complete recovery will be obtained from the swept regions. Thus, for any specified set of reservoir conditions, an optimum use of solvent is defined. INTRODUCTION The early outlook for solvent flooding as a means to increase oil recovery was very favorable. Some laboratory results indicated that a "slug" containing perhaps 2 to 3 per cent of a hydrocarbon pore volume could be successful. However, other data suggested as much as 30 per cent would be required. The difference is of considerable economic importance. A theoretical explanation for these divergent results has been advanced by the author.1,2 Stability theory defines conditions for two distinct flow regimes. In stable displacement, solvent and oil become mixed by a dispersion process, and the solvent requirement is small. On the other hand, unstable displacement can degenerate into viscous fingering. The practical result is a considerable increase in the extent of mixing and, thus, in the solvent required. The present paper shows how to use stability theory to optimize solvent recovery of oil. Oil is usually considered to be displaced by a small amount, or a slug, of solvent. Gas in turn follows solvent. Any fingering will permit contact of nearly solvent-free gas and oil, leading to immiscibility and reduced recovery. Thus, our optimum is defined by two restrictions — stable flow and miscibility. Although an immiscible solvent process could prove more profitable than any miscible process, such processes lie outside the selected definition of an optimum. The usefulness of computations based on the present work will depend on the validity of the general theory. Because the important idealizations required tend to minimize the predicted solvent requirement, the results should state correctly the limiting conditions required. Therefore, theoretical calculations should have practical value. This paper first reviews several principles that result from stability theory. The following section describes use of these ideas in relatively simple systems which symmetry makes appear one-dimensional. Of particular importance is the step-by-step design of 3 stable minimum-solvent slug. The use of stability theory in cases of multi-dimensional displacement is discussed and, finally, suggestions are given for simplified practical application of the theoretical results. PRINCIPLES OF STABILITY THEORY The use of perturbation methods to derive stability conditions has been shown by the author.l The discussion is presented in terms of the fractional concentration of solvent in the single hydrocarbon phase. Quite generally, any disturbance can be represented as a Fourier series, of which only the least stable term need be considered. Denoting this term at time t = 0 by cn,

By S. Meng, R. Jin, W. Hu

In alkaline pulp, galena is depressed by sodium carboxymethyl cellulose (NaCMC), while Cu(II) -activated sphalerite exhibits a high floatability so that satisfactory separation can be achieved. In addition to hydrogen bonding, chemical bonding of NaCMC with galena is confirmed by infrared (IR) spectra; only hydrogen bonding is involved between NaCMC and Cu(II)-activated sphalerite. It is also found that the greater the degree of substitution and polymerimtion of NaCMC, the stronger the depressive effect of NaCMC and that lower stirring speed favors the depression.

Jan 1, 1988

By A. B. Young

In the original design of the flue system, the flues from the roasters delivered their gases to a large brick dust chamber which discharged into another flue with stack connection, as shown in Fig. 1. The treater is so situated that the gases are taken by it directly from the chamber and discharged again into the flue. The complete installation comprises two treater units, only one of which has been installed at present. The treater is essentially a flue 1.0 ft. high, 12 ft. wide, and 61 ft. long. (3 by 3.6 by 18.5 m.). Suspended inside, vertically and running lengthwise, are four banks of No. 20 corrugated iron plates; each bank is 10 ft. long, making an effective treater length of 40 ft. The spacing from center to center of the rows of plat,es is 9 1/8 in. (23 cm.) giving six-

Jan 1, 1921

By Paul Worsey, Gillian Worsey

The explosives industry is about to reach a critical turning point in human resources. The average age of employees of the largest US explosives company is over 50 and an estimated 5,000 engineers are due to retire from the mining industry over the next decade, with less than 200 mining graduates per year nationally. Not just in the USA, this is a worldwide problem. In Canada the Mining Industry Human Resources Council (MIHRC), reported that older mining engineers are retiring early – at the age of 59.5 on average. It predicts that mining companies will need to hire 370 mining engineers by 2016 and 665 by 2021. The Minerals Council of Australia has predicted the need for an additional 86,000 mining professionals and skilled mine workers by 2020, and the Indian mining industry is also facing a shortage of between 2,500 to 3,000 engineers per year.

Jan 1, 2014

By Rikiya Kamezawa, Rudiono, Manabu Takeuchi

"Schottky type solar cells based on phthalocyanine (Pc) thin films were fabricated, and their photovoltaic performance was investigated in various ambient atmospheres. Most of cells prepared in this study showed a good rectification and photovoltaic effects in the visible wavelength region. The introduction ofN02 gas into the measuring chamber was confirmed to increase the current both in dark and under light illumination. However, chemical reaction between the Al electrode and N02 formed some oxide and deteriorated the Schottky barrier, resulting in an increase in cell resistivity. SF 6 gas also showed similar effects on the cell performance.IntroductionPhthalocyanine is one of the typical organic semiconductors, which shows high photoconductive sensitivity in the visible to infrared region. Today, several kinds of metal phthalocyanines are used in electrophotographic photoreceptors. In addition, application of phthalocyanines to solar cells have also been trying by many workers [1, 2]. Many efforts have been made for improving performance of phthalocyanine solar cells by modification of device structure [3, 4], doping by dye or pigment [5, 6] and incorporation of metal clusters [7]. It is known that electrical conductivity in phthalocyanine is increased by adsorption ofNO2 [8, 9]. We tried to improve photovoltaic performance ofphthalocyanine solar cell by adsorption ofNO2. This paper describes the influence of N02 adsorption on the photovoltaic behavior of phthalocyanine solar cells."

Jan 1, 2000

By Julianne H. Glarmaty, Peter J. Conroy

INTRODUCTION In 1970 the percentage of underground coal extraction by longwall mining methods in the U.S. was 2.1 percent. This figure rose to 4.4 percent in 1976 and is expected to rise to 12 percent by the year 1985. This figure represents 46.0 million tons (51.0 million st) of annual production (Kuti, 1978). In addition, OSM regulations are placing emphasis on subsidence prediction. Section 784.20 of the Office of Surface Mining regulations for underground mining permit applications requires the sutauission of a subsidence control plan which may include monitoring. Because of its nature, longwall mining does not have flexibility in leaving pillars under structures as does room and pillar. Mining in some areas, particularly in the Eastern Coal Field, is approaching more developed areas; therefore, a greater number of structures are expected to be undermined in the near future. Subsidence engineering is becoming an important aspect of mine planning, and should be directed at predicting potential structural damage. The question operators are increasingly faced with is "what will be the subsidence effects for a specific structure at a specific location in respect to a longwall panel?" The most significant variable in assessing the subsidence effect on structures is not vertical subsidence. The variables of strain and tilt are responsible for more structural damage than is the vertical movement. Table I presents threshold values of strain for various structures (Geddes 6 Cooper, 1962). Based on National Coal Board experience, horizontal strain is approximately inversely proportional to the radius of curvature of a circular portion of a subsidence profile; therefore, the radius may be useful in estimating the magnitude of strain caused by subsidence (Hoebs, 1982). The radius of curvature can be determined by the following equation:

Jan 1, 1982

By H. A. Baumann, A. J. Rostosky

EVER since the first installation of wet-washing methods of coal preparation, the removal of the water added by the washing process has created serious technical and operating problems. The rapid development and widespread adoption of wet washing has necessitated a corresponding development of dewatering methods and equipment. The amount of water retained by coal varies with the size of the coal. The moisture that is largely on the surface of the particles is easily shaken off coarse coal; thus coarse coal can be dried comparatively easily and quickly. Fine coal presents a larger surface area than does coarse coal, so its capacity for retaining moisture is greater. In fine coal, moisture below about 5 per cent is held between the coal particles and its removal is difficult. Draining and drying of the finer sizes is a major problem at many washeries. Two common problems of coal-washing practice that are intimately connected with dewatering and drying are the clarification of washery water and the prevention of stream pollution. The first field has been studied from many angles, including the use of coagulating and settling agents followed by vacuum filters to remove the solids, and the use of sludge tanks with dewatering screens incorporated therein. In many districts, the disposal of sludges into streams has been stopped by law. The lack of space for impounding sludges has created problems of disposal in other districts. Reduction in moisture means a saving in freight costs as well as the elimination of difficulties in unloading and storing. Excess moisture in coal causes it to freeze in localities where severe climatic conditions pre¬vail. Excess water in coals to be used in the production of coke and manufactured gas has a chilling effect on the walls of the oven or retort. Dryness of coal is important in producing good briquettes.

Jan 1, 1943

By S. S. Arentz

An organized safety program has reduced accidents at Pioche because effort is first devoted to arousing and maintaining interest in safety, followed by training in accident prevention, assigning responsibility for the detection and removal of safety hazards, and finally, by keeping score through an adequate system of records. A health program is intergrated with the safety program.

Jan 2, 1950

By S. Y. Han

INTRODUCTION More than 97% of the total uranium production of the United States comes from sedimentary deposits (1). These sandstone deposits were formed by reduction of migrating uranium-bearing solutions from volcanic silicate rock sources. Such deposits occur in two major forms, either as relatively flat, lens-like deposits or as crescent- shaped roll front deposits. The lens-like deposits are found as discrete masses enclosed in reduced sandstone which is generally surrounded by oxidized sandstone. The roll front deposits are found along crescent-shaped interfaces between reduced and oxidized sands tone (2). In-situ mining of selected sedimentary deposits has proven to be a viable method of extraction and competitive with conventional mining for relatively deep low-grade ores (2). In in-situ leaching, uranium is recovered by drilling injection and collection wells in the ore body, pumping a suitable lixiviant to dissolve the mineral, extracting uranium from the pregnant solution by ion exchange, and finally regenerating and recycling the lixiviant. Even though there is increasing interest and practice in developing the in-situ technique for obtaining uranium values from deeper, lower-grade reserves, there is a lack of knowledge of the basic leaching kinetics and combined transport processes. In-situ leaching operations, in general, appear attractive for the following three general types of deposits (2): (1) low-grade surface dumps or deposits which lie above the natural water table,

Jan 1, 1983

By X. W. Pan

It has been found that the MnO content of a slag decreases sharply when direct current is applied to a 1T1£tal-Slagsystem consisting of liquid Mn-Si-Ccsat metals and MnO-SiO2-CaO-AI203 slag in graphite crucibles. This paper reports a preliminary investigation into the electrochemical effects of direct current on the metal-slag system, the silicon content of the metals, and the MnO content of the slag. The results show that, when a direct current of 7 A is maintained, the MnO content of a metal containing 10 to 11 per cent silicon by weight is reduced rapidly from 26,5 to 17,2 per cent by weight. This reduction seems to proceed further when the process is continued. When the direct current and the voltage are kept constant at TA and 4 V respectively, the MnO content of a metal containing 1 to 2 per cent silicon by weight is reduced to 1 from 25 per cent by weight, which results in a manganese yield of 96 per cent.

Jan 1, 1995

By Howard I. Smith

POTASH is of prime importance as a plant food and is also widely used in industry. The term "potash was applied to a crude pearlash obtained by evaporating, in iron pots, solutions leached from plant ashes. Later it included caustic potash obtained by treating pot ashes with lime, and now it is applied generally to various compounds of potassium used by agriculture and industry. Herein it applies to the theoretical equivalent in potassium oxide (K20)--a compound never found in nature or manufactured in commerce but generally used as a common denominator for comparison of all potassium compounds. Potash was made from plant ashes at an early date, but potassium in mineral form was not noted until 1797, when it was identified in leucite.3 The importance to plant life of potash in the soil was first recognized by von Liebig3 and his published reference thereto appeared in 1840. In 1843, potash was discovered in the brine of a well drilled for salt near Stassfurt. HISTORY OF THE AMERICAN POTASH INDUSTRY Among the colonists reaching Virginia in 1608 were men from Poland skilled in making potash from wood ashes19 and records show that the production of potash was begun in other colonies also, soon after their establishment. The American product entered the trade in 1635, and at various times since that date the production of potash for industry has been subsidized by the Government or protected by tariffs. The production of potash from wood ashes reached its peak in 1825. Beginning in 1823, a cheaper product, sodium carbonate, made by the Leblanc process, was substituted for much of the potash used in industry. Production rapidly declined after the Civil War, when the forests most productive of potash had become depleted and labor had become

Jan 1, 1949

By Geoffrey Gilbert

THE Montana Phosphate Products Co., subsidiary of the Consolidated Mining and Smelting Company of Canada, operates three phosphate properties north and northeast of Garrison, Powell County, Mont. Production of all three is from the same phosphate bed, a 3 to 4-ft. member of the Phosphoria formation, whose outcrop is traceable across the mountains of the Garnet Range in a series of southeasterly pitching folds. Because of topographical differences and of variations in the attitude of the bed, each property has its own mining methods and problems. Most of the phosphate rock produced since I930 has been shipped to the plant of the Consolidated Mining and Smelting Co. at Trail, B.C., where it is treated with sulphuric acid for conversion to phosphoric acid, which in turn is used to produce various fertilizers. HISTORY The occurrence of rock phosphate in Montana has been known. since 1910, and the Garrison area was mapped by the United States Geological Survey in 1913In the nineteen twenties William Anderson, owner of a ranch 8 miles north of Garrison, discovered phosphate on his land, and the Montana Phosphate Co., which later became the Montana Phosphate Products Co., was formed to work the deposit. Montana Phosphate Products Co. later obtained United States leases on two adjoining parcels of ground, and this combined property, known as the Anderson mine, has been the main source of Consolidated's phosphate rock. The mine now includes an adjoining parcel leased from Anaconda and mined from the Anderson workings. In 1940, the Graveley mine, a small privately owned property 6 miles east of the Anderson, was leased from the owner by Montana Phosphate Products Co., and a U. S. lease held by Graveley on some adjoining ground was subleased. In 1943 the Luke mine, on the Mineral Hill property, 1 ¾ miles south-southwest of the Graveley, a U. S. lease, which previously had produced a few thousand tons, was optioned from the lessees by Montana Phosphate Products Co., and is now being developed. At both these mines the rock is appreciably higher grade than at the Anderson mine. GEOLOGY The Phosphoria formation is the Permian member of an extensive sequence of Paleozoic and Mesozoic rocks. It is underlain by Pennsylvanian (Quadrant) quartzite and Mississippian limestone, and overlain without any marked unconformity by Jurassic (Ellis) shale and Cretaceous shale and sandstone. In the Garrison area, the Phosphoria itself consists mainly of about 50 ft. Of gray to yellow chert. Immediately below the chert is the phosphate, usually 3 to 4 ft. thick. Below the phosphate occur a few

Jan 1, 1945

By Geoffrey Gilbert

The Montana Phosphate Products Co., subsidiary of the Consolidated Mining and Smelting Company of Canada, operates three phosphate properties north and northeast of Garrison, Powell County, Mont. Production of all three is from the same phosphate bed, a 3 to 4-ft. member of the Phosphoria formation, whose outcrop is traceable across the mountains of the Garnet Range in a series of southeasterly pitching folds. Because of topographical differences and of variations in the attitude of the bed, each property has its own mining methods and problems. Most of the phosphate rock produced since 1930 has been shipped to the plant of the Consolidated Mining and Smelting Co. at Trail, B.C., where it is treated with sulphuric acid for conversion to phosphoric acid, which in turn is used to produce various fertilizers. History The occurrence of rock phosphate in Montana has been known since 1910, and the Garrison area was mapped by the United States Geological Survey in 1913. In the nineteen twenties William Anderson, owner of a ranch 8 miles north of Garrison, discovered phosphate on his land, and the Montana Phosphate Co., which later became the Montana Phosphate Products Co., was formed to work the deposit. Montana Phosphate Products Co. later obtained United States leases on two adjoining parcels of ground, and this combined property, known as the Anderson mine, has been the main source of Con-solidated's phosphate rock. The mine now includes an adjoining parcel leased from Anaconda and mined from the Anderson workings. In 1940, the Graveley mine, a small privately owned property 6 miles east of the Anderson, was leased from the owner by Montana Phosphate Products Co., and a U. S. lease held by Graveley on some adjoining ground was subleased. In 1943 the Luke mine, on the Mineral Hill property, 1 3/4 miles south-southwest of the Graveley, a U. S. lease, which previously had produced a few thousand tons, was optioned from the lessees by Montana Phosphate Products Co., and is now being developed. At both these mines the rock is appreciably higher grade than at the Anderson mine. Geology The Phosphoria formation is the Permian member of an extensive sequence of Paleozoic and Mesozoic rocks. It is underlain by Pennsylvanian (Quadrant) quartzite and Mississippian limestone, and overlain without any marked unconformity by Jurassic (Ellis) shale and Cretaceous shale and sandstone. In the Garrison area, the Phosphoria itself consists mainly of about 50 ft. of gray to yellow chert. Immediately below the chert is the phosphate, usually 3 to 4 ft. thick. Below the phosphate occur a few

Jan 1, 1948

By Geoffrey Gilbert

The Montana Phosphate Products Co., subsidiary of the Consolidated Mining and Smelting Company of Canada, operates three phosphate properties north and northeast of Garrison, Powell County, Mont. Production of all three is from the same phosphate bed, a 3 to 4-ft. member of the Phosphoria formation, whose outcrop is traceable across the mountains of the Garnet Range in a series of southeasterly pitching folds. Because of topographical differences and of variations in the attitude of the bed, each property has its own mining methods and problems. Most of the phosphate rock produced since 1930 has been shipped to the plant of the Consolidated Mining and Smelting Co. at Trail, B.C., where it is treated with sulphuric acid for conversion to phosphoric acid, which in turn is used to produce various fertilizers. History The occurrence of rock phosphate in Montana has been known since 1910, and the Garrison area was mapped by the United States Geological Survey in 1913. In the nineteen twenties William Anderson, owner of a ranch 8 miles north of Garrison, discovered phosphate on his land, and the Montana Phosphate Co., which later became the Montana Phosphate Products Co., was formed to work the deposit. Montana Phosphate Products Co. later obtained United States leases on two adjoining parcels of ground, and this combined property, known as the Anderson mine, has been the main source of Con-solidated's phosphate rock. The mine now includes an adjoining parcel leased from Anaconda and mined from the Anderson workings. In 1940, the Graveley mine, a small privately owned property 6 miles east of the Anderson, was leased from the owner by Montana Phosphate Products Co., and a U. S. lease held by Graveley on some adjoining ground was subleased. In 1943 the Luke mine, on the Mineral Hill property, 1 3/4 miles south-southwest of the Graveley, a U. S. lease, which previously had produced a few thousand tons, was optioned from the lessees by Montana Phosphate Products Co., and is now being developed. At both these mines the rock is appreciably higher grade than at the Anderson mine. Geology The Phosphoria formation is the Permian member of an extensive sequence of Paleozoic and Mesozoic rocks. It is underlain by Pennsylvanian (Quadrant) quartzite and Mississippian limestone, and overlain without any marked unconformity by Jurassic (Ellis) shale and Cretaceous shale and sandstone. In the Garrison area, the Phosphoria itself consists mainly of about 50 ft. of gray to yellow chert. Immediately below the chert is the phosphate, usually 3 to 4 ft. thick. Below the phosphate occur a few

Jan 1, 1948

By W. A. Hoyer

A pulsed high-energy neturon-induced spectral logging tool has been built and field-tested. The reaction of deuterium on tritium is used to generate pulses of 14-Mev neutrons. By detecting only the prompt gamma rays produced by neutron inelastic reactions in the formation, the presence and relative abundance of carbon, oxygen, calcium, silicon and other important elements may be ascertained from a gamma-ray spectrum. Gamma-ray spectra obtained in a shallow test well and in experimental field use show that it is possible to identify formations and their contained fluids. INTRODUCTION The penetrating gamma rays from naturally occurring radioactive elements in subsurface formations have been used for a number of years in well logging as a means of characterizing and distinguishing strata. Still another nuclear logging method which has been employed for some years consists of the bombardment of strata with neutrons and the measurement of the number of gamma rays produced by neutron capture reactions involving elements in subsurface strata.' Since one of the principal elements entering into capture reactions is hydrogen, the latter procedure essentially results in a hydrogen log, whether the hydrogen be in combined form in either oil or water; thus, the log gives an indirect measure of porosity. These methods, with various refinements, have been developed to such an extent that they have become routine procedures in formation evaluation. Neither gamma-ray logging nor conventional neutron logging, however, yields sufficient information to permit unequivocal identification of the mineralogic composition of formations, and neither method gives information which may be used for the positive identification of hydrocarbons in strata. Accordingly, a number of efforts have been made in recent years to gain additional information from nuclear logs. Brannon and Osoba have shown that it is possible to identify naturally occurring radioactive elements in subsurface formations by spectral analysis of gamma rays emanating from these elements. Such an identification is of value in the characterization of strata. A simplified form of spectral analysis of gamma radiation resulting from neutron capture reactions between elements in earth materials and bombarding neutrons has been used with some suc- cess under favorable conditions to differentiate between petroleum and water. This method relies upon the relatively high energy of gamma radiation from neutron capture by chlorine and, in effect, furnishes a chlorine log. In areas in which interstitial water is of sufficiently high salinity, this log can give valuable information on water saturation and, thus, indirectly on hydrocarbon saturation. Still another approach to obtaining more information by nuclear techniques is "activation logging", in which certain elements yield short-lived radioactive isotopes on neutron activation and, thus, can be detected by gamma-ray spectral analysis. From the standpoint of determining by nuclear logging methods the mineralogic composition of strata and the presence or absence of hydrocarbons, it is essential that information be obtained on the presence and relative amounts of several elements such as carbon, oxygen, hydrogen, calcium, silica and others. Some elements, such as hydrogen, chlorine and sulfur, can be determined by spectral analysis of gamma radiation resulting from neutron capture reactions."" Others — carbon and oxygen, for example — do not enter readily into capture reactions but do yield gamma rays of characteristic energies from inelastic scattering reactions with high-energy neutrons. Accordingly, the latter reactions are of particular interest as a means of identifying hydrocarbons in subsurface strata. Several years ago it was recognized that information requisite to the identification of subsurface strata and of contained fluids could be obtained by pulsed operation of a subsurface neutron generator and associated gamma-ray detector. It was contemplated that pulsed operation would be effective in discriminating in time that gamma radiation which results predominantly from inelastic scattering reactions from that gamma radiation arising from neutron capture reactions. Accordingly, research was continued and construction of such a device was initiated. Although many problems were encountered, they were solved successfully. The following sections describe the tool which has evolved, its performance and the results which have been obtained with it to date. THEORY OF OPERATION OF NEUTRON-INDUCED GAMMA-RAY SPECTRAL LOGGING TOOL THEORY OF INDUCED NUCLEAR REACTIONS Of fundamental importance is the fact that an element, when bombarded with neutrons, emits gamma radiation of energy characteristic of that element. In theory, therefore, an element may be identified by

Develop improved blasting practices that can help to curb overbreak in highwalls at surface mines, thereby reducing the hazards of rock-falls to workers and equipment, The Problem The serious hazard in surface mining is the falling of rock from highwalls. Poor highwall stability is caused in part by geologic conditions, but often is aggravated by faulty blasting practices, where the explosive energy not only fractures the rock to be excavated, but also damages the rock that borders the excavation. This reduces the general stability of the hlghwall and increases the rockfall potential. The probability of injury to mine workers or damage to equipment associated with exposure to the highwall increases with the height of the highwall and the extent of its overbreakage. Most rockfalls occur in the first 15 days after a new highwall is exposed. This statistic is significant since most of the work below a highwall is done during this period. The area of greatest hazard is within 25 ft of the toe for rocks that fall vertically, and up to 90 ft from the toe for falling rocks that are deflected by the highwall during their descent, The workers most frequently involved in such accidents are dozer operators, ground laborers, and shovel operators or oilers.

Jan 1, 1985

By Warren Blauvelt

IN VIEW of the enormous wastes of natural resources, of labor and of capital, due primarily to the economic environment, established by legislation, the general neglect of this phase of the problem of the elimination of waste is difficult to understand. In such a study, the engineering method of attacking a problem should be employed. The engineer does not try to solve his problem by disregarding natural laws, but by utilizing them. The successful engineer establishes an environ-ment in which forces, acting in harmony with natural laws upon an object or objects, will produce the desired results. The engineer who notices that the water level in a vessel, into which a gallon of water per minute is flowing, is two feet higher than the level in an adjacent vessel, connected therewith by a 6-in. pipe, does not assume that the law of gravity has ceased to work, or that water no longer seeks its level; he examines the connecting pipe for obstacles which prevent the free flow of water. Some editors, many reformers and most politicians tell us that the law of supply and demand no longer works; hence governmental control of commerce is necessary. Governmental control may temporarily-that is, until trial proves its futility- "insure domestic tranquility" and "promote the general welfare;" but it cannot "secure the blessings of liberty" which it cur-tails, nor can it "establish justice" which it violates.

Jan 9, 1922

By Victor Lenher

The interest shown recently in selenium and tellurium has brought many requests for an assembling of the analytical chemistry of these two elements. The intention of this paper is to discuss all of the chemical principles utilized in the detection and quantitative determination of these elements, as well as to describe the works methods actually followed by producers of tellurium and selenium in the United States. These methods have been furnished by S. Skowronski of the Raritan Copper Works, H. D. Greenwood of the United States Metals Refining Co., F. F. Colcord of the U. S. S. Lead Refinery, and E. W. Rouse and A. E. Hall of the American Smelting and Refining Company. Occurrence Selenium is found associated with sulfur, to which in many respects it is quite similar. Occasionally deposits of native sulfur, notably those in the Lipari Islands, Kilauea, and Japan, show a red-brown coloration, I which is readily distinguished from that of other sulfur; this red-brown * sulfur contains a small amount of selenium. Not infrequently, the , sulfides of the heavy metals are accompanied by selenium and tellurium, • presumably as selenides and tellurides. The Scandinavian pyrite, which is one of the large sources of European sulfuric acid, when roasted has fur- - nished a large part of the selenium that has come to the United States; it I was in flue dust from the roasting of Scandinavian pyrites that the element was discovered by Berzelius in 1817. Greek and Spanish pyrites also

Jan 1, 1923

By Victor Lenher

The interest shown recently in selenium and tellurium has brought many requests for an assembling of the analytical chemistry of these two elements. The intention of this paper is to discuss all of the chemical principles utilized in the detection and quantitative determination of these elements, as well as to describe the works methods actually followed by producers of tellurium and selenium in the United States. These methods have been furnished by S. Skowronski of the Raritan Copper Works, H. D. Greenwood of the United States Metals Refining Co., F. F. Colcord of the U. S. S. Lead Refinery, and E. W. Rouse and A. E. Hall of the American Smelting and Refining Company. Occurrence Selenium is found associated with sulfur, to which in many respects it is quite similar. Occasionally deposits of native sulfur, notably those in the Lipari Islands, Kilauea, and Japan, show a red-brown coloration, I which is readily distinguished from that of other sulfur; this red-brown * sulfur contains a small amount of selenium. Not infrequently, the , sulfides of the heavy metals are accompanied by selenium and tellurium, • presumably as selenides and tellurides. The Scandinavian pyrite, which is one of the large sources of European sulfuric acid, when roasted has fur- - nished a large part of the selenium that has come to the United States; it I was in flue dust from the roasting of Scandinavian pyrites that the element was discovered by Berzelius in 1817. Greek and Spanish pyrites also

Jan 1, 1923

By A. F. Taggart, F. E. Beach

The flotation process for the concentration of ores is a method by means of which one or more of the minerals in the ore (usually the valuable ones) are picked up by means of a liquid film and floated at the surface of a mass of fluid pulp. Here they are separated from the other minerals, which remain immersed in the body of the pulp. In general, the minerals which are floated are sulphides of metallic luster, but some other minerals of metallic luster such as graphite and some sulphides with adamantine luster, such as sphalerite and cinnabar, are amenable to treatment by the process. The importance of flotation lies in the fact that it is primarily a "slimes process" by means of which the particles of valuable mineral, too fine for efficient gravity concentration, are saved with a high percentage of recovery. Recoveries in the mills treating low-grade copper sulphide ores have been advanced 10 to 20 per cent. by the installation of the process and similar increased savings have been accomplished by the same means in mills treating sulphide ores of zinc and lead. When finely ground ore containing sulphides mixed with a siliceous or earthy gangue is brought gently onto the surface of a body of water, in a direction forming an acute angle with the surface of the water, a considerable portion of the sulphide constituent of the ore floats on the surface of the liquid, while the gangue sinks. This is the so-called film flotation, exemplified by the Wood and Macquisten processes. When gas bubbles are introduced into a fluid pulp composed of finely ground ore and water, to which has been added (1) a small amount of certain oils, or (2) a small amount of certain acida or acid salts, or (3) a small amount of certain alkalis or alkaline salts, or (4) a small amount of a mixture of oil with acid or alkali, the sulphide particles in the ore are brought to the surface on the gas bubbles. These collect in a froth

Jan 1, 1917