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By G. W. Healy, D. C. Hilty

MAJOR considerations in the production of stainless steel are the utilization of stainless steel scrap and the recovery of chromium and other metallic values from the initial furnace charge. The decarburization of a bath of molten chromium steel with gaseous oxygen is usually accompanied by a considerable amount of metallic oxidation. Since recovery of this metal from the slag may require substantial expenditures of time and materials for slag reduction, holding metallic oxidation to the minimum consistent with good operating practice is generally desirable. The important role of temperature in minimizing metallic oxidation is illustrated by Fig. 1, taken from the results of Hilty, Healy, and Crafts,' who established the quantitative relations connecting the amounts of chromium, manganese, and iron oxidized during the oxidizing period of chromium steel heats with the composition of the initial charge and the temperature and composition of the molten bath after oxidation. Higher temperatures after the oxygen blow result in lower metallic oxidation. Although high temperatures are desirable for minimizing metallic oxidation, practical operating considerations limit the degree to which they can be employed. Excessively high temperatures or prolonged operation at moderately high temperatures may cause serious damage to the furnace refractories, so that a compromise must be effected. The problem, therefore, is one of controlling the oxidizing period of chromium steel heats to the shortest time at the highest practical temperature. The most effective tool the steel melter has for attaining high temperature while decarburizing a chromium steel heat is now commonly considered to be the oxygen lance with an adequate supply of gaseous oxygen. In order for the tool to be effective, however, the heat resulting from the oxidation of carbon, chromium, silicon, manganese, and iron in the bath must exceed the heat losses from the furnace. General recognition, of this principle has stimulated a trend toward faster injection of oxygen. For example, Pachaly2 proposed a high temperature at the start of the oxygen blow or a high rate of oxygen input as a means of obtaining the desired carbon level with high chromium recovery. On the other hand, limited understanding of the specific effects of oxygen input rate has hampered development of optimum practices. As part of a broad study of the metallurgy of chromium steel melting, therefore, the Linde Air Products Co. and the Electro Metallurgical Co. at their Metals Research Labo-ratories have evaluated the heat-balance during the oxidizing period in terms of oxygen input rate. The evaluation has then been related to factors such as temperature increase, metallic oxidation, oxygen Utilization, etc., and extrapolated to include a wide

Jan 1, 1958

By J. G. Richardson, F. M. Perkins

Results and procedures are pre-cented covering a laboratory investigation of the effect of rate of water advance on the displacement of oil from clean water-wet sands. The experiments included water floods at atmospheric pressure with and without gas present over a range of flow rates from reservoir rates to rates ten thousand-fold higher. Water floods were also conducted at various rates at elevated pressure with no gas present. Other tests were made at elevated pressures by forming a free gas saturation by evolution of gas from solution in the oil before water flooding. Recovery of oil was found to be independent of the rate of water advance with or without gas present and independent of the pressure level of the water flood. A dimensionally-scaled model of a reservoir composed of a thick uniform sand was used to study the effect of rate on the tendency of water to underrun the oil because of the greater density of the water. Another model was used to study the effect of rate on the tendency of water to channel down the more permeable sand in a stratified reservoir composed of sands of diffierent per-meability in intimate contact. The effect of the presence of gas on the flooding conformance was studied with both models. The results obtained using these simple models provide a basis for predicting behavior in more complicated systems. INTRODUCTION In spite of the great amount of research on the flow of fluids in porous rocks, there still exists some disagreement as to the influence of the rate of water advance on the displacement of oil by water flooding. Various investigators have found that increasing the rate of water injection would decrease, increase, or have no effect on recovery of oil. One reason for this disagreement has been a lack of understanding of the effects of the capillary forces which influence the results obtained in the laboratory at low rates with short columns. Other causes of the disagreement have undoubtedly been inconstancy and uncertainty of the wetting properties of the porous media studied, inaccurate saturation determinations, and in some instances conclusions based on insufficient data. Capillary forces are involved in the displacement of oil by water in two ways. On the microscopic scale, the capillary forces control the dis- tribution of oil and water in the pore spaces of the sand. The magnitude of these forces is governed by the preference of the sand to be wet by water, the pore sizes and geometrical shapes, and the interfacial tension between the water and oil. On the macroscopic scale, differences in saturation at the flooding "front" when water displaces oil result in capillary pressure gradients. These gradients cause water to flow preferentially ahead of the front. In short laboratory columns at low rates, the front can span the entire column length. Also, at the outflow boundary the preference of sand to be wetted by water results in retention of water and a high water saturation in the region of the outflow face. This effect is commonly called the boundary effect.' The capillary pressure gradients which complicate the interpretation of flooding performance of short laboratory columns at low rates of water advance become negligibly small under certain conditions. The conditions where capillary pressure gradients are negligible are in long, homogeneous reservoir sands,' at high rates of water advance in short laboratory columns,3 and at any rate in laboratory columns as the residual oil saturation is approached. Thus, laboratory water floods, conducted

Jan 1, 1958

By K. F. Unrug

Eastern coalfields have been extensively strip mined. In the past, contour mining left vast areas of post-mining highwalls and benches. Thin seams, which cannot be feasibly mined with conventional methods, quite often contain substantial reserves of high quality coal. Unconventional secondary recovery methods may permit economical production of that coal, increased use of reserves, and provide resources for restoration of orphaned land. Technical and rock mechanics implications of secondary mining methods are discussed to determine their limitations and the objectives of required research.

Jan 1, 1986

By Alexander L. Holley

Jan 1, 1879

By Thomas S. Nye

Mineral exploration in the United States relies heavily on theoretical geologic concepts and indirect methods such as geophysics and geochemical prospecting, as there are few exposed areas of mineralization which have not already been explored. In Mexico, ore grade samples can be cut at the surface on vein, replacement, and disseminated types of deposits in many areas. The problem is not in finding a mineralized area but in deciding which mineralized area can be explored and developed at the least risk and cost, with the greatest profit potential within the framework of Mexican mineral economics and that nation's government policies. Socio-economic Posture Mexico, prior to World War II, had suffered from more than one hundred years of intermittent wars and exploitation by internal and foreign elements. Consequently, the basic facilities which today's society takes for granted were scarce or non-existent in most of the country. Travel was largely a matter of negotiating poor dirt roads, riding horseback or walking. Relatively few people were literate and medical facilities were luxuries for the wealthy. Mexico's leaders were, however, determined to improve the lot of their people, within a system of private enterprise and personal freedom. Long-range programs initiated at about the time of World War II to provide infrastructure-education, health and welfare, transportation, power, water, communication-are now established fully or in part for most of the country and are being continually expanded.

Jan 12, 1972

By H. Ries

SPECIAL sands are those that are employed for special purposes. They have a limited use, as compared with sands for concrete and plaster. The sands discussed in this chapter are those used for foundry purposes, glass manufacture, filter beds, abrasive purposes, sandblasting, engine sand, sand for sheet asphalt, and furnace sand. These sands are almost invariably high in silica, consisting chiefly of quartz grains. In some-for instance, glass sands-freedom from ingredients other than silica, such as iron oxide, is important. Certain grades, like filter sand, require rather careful sizing, and in foundry sands the bond, usually clay, is important. One deposit may sometimes be used to supply several grades or types of sand by appropriate methods of screening and washing. The special sands discussed here are usually obtained from deposits of unconsolidated material but sands high in silica are derived occasionally from soft sand- stones that can be disintegrated easily. Requirements are not the same for all uses, and, while certain properties may be demanded, there are no officially adopted standard tests except for foundry sands. FOUNDRY SANDS Definition-Foundry sands include those siliceous sands that are used to make the forms for casting metals. If these are employed for making molds, they are known as molding sands; if for the cores that form the hollow spaces in the casting, they are called core sands. Naturally bonded sands are those containing a variable, though not usually large, amount of clay, which serves as a bond. Synthetic sands, now much used, represent an artificial mixture of sand with usually fire clay or bentonite. Core sands may be bonded with oil, cereal binders, resin, pitch, or other materials. The foundrymen apply the term "sharp sand" to one that is free from bond. Properties-The important properties to be tested at room temperature are texture or fineness, permeability, strength, deformation, and flowability. Those tested at elevated temperatures are compressive strength, expansion and contraction, sintering point, and durability. More attention probably has been given to research on the properties

Jan 1, 1949

By Thomas Fraser, Abreu Alvaro

THE work described in this paper was carried out under the sponsorship of the Foreign Economics Administration and in cooperation with the Departamento Nacionál da Produção Mineral, Rio de Janeiro. The project was undertaken to obtain complete data on the variations in washability of coal to be used for coke manufacture in the steel industry and to determine the economy of preliminary hand-sorting operations. The coal-producing industry of Brazil is in that pioneering stage in which operat¬ing practices and methods are just being developed. Increased wartime demand for fuel, coincident with a drastic curtailment of foreign supplies due to lack of shipping facilities, has put a tremendous pressure on the national industry to furnish more coal. Under this incentive, production facilities are being expanded and new methods of operation are being tested. Such changes are being developed both by improvement of existing methods that originated in the field and by adaptation and modification of methods introduced from the United States and Europe. These mining condi¬tions and mining practices in Brazil are typical of what the American mining engineer will find in many instances when he goes pioneering into the developing coal fields of the Southern Hemisphere. The producing coal fields of Brazil are all in the southern states of that country. The coal measures are in a band roughly paralleling the coast and extending in a generally southwesterly direction from northern São Paulo through the states of Paraná, Santa Catarina and Rio Grande do Sul to near the Uruguayan border in the vicinity of Bajé. The accompanying map1 (Fig. I shows the general location of these fields and also the principal routes of movement of both national and imported coal in a late pre-war year (1940). Statistical data on production by states up -to that year are given in Table I. Rio Grande do Sul is still the largest producer among the coal states; but wartime

Jan 1, 1946

By Bailey Willis

It is proposed to present some of the results of observation of the geologists of the Appalachian division during the past seven years, and of experimental study during the past three years, on the subject of structural geology in the Appalachian Province. The article must be brief, even at the risk of obscurity; but a more complete and fully illustrated paper will appear in the Thirteenth Annual Report of the United States Geological Survey. Certain Facts. The following facts are first to be taken account of: From the Cambrian age to the Carboniferous there existed a conti nent stretching southeast from the present range of the Blue Ridge, covering what is now eastern Pennsylvania, New Jersey, eastern Vir ginia, North and South Carolina and eastern Georgia, with some un known part of the present Atlantic ocean-bed. Northwest from this continent lay a sea, reaching to the west and north of the Mississippi. Sedimentary deposits derived from the land accumulated with or ganic remains, in the sea; the greater part fell in a narrow zone along the shore, the remainder spread in a comparatively thin sheet over the bottom of the Mediterranean of North America. The resulting strata measure, near Mauch Chunk, Pa., 30,000 feet; over much of Pennsylvania, 20,000 to 25,000 feet; over eastern Tennessee, Georgia and Alabama, but 10,000 to 15,000 feet. The stratified mass, considered with reference to its broad physical char acters, consists of three members: A base of shale and sandstone ; a middle of limestone, 2500 to 6000 feet thick—a stratum probably not equalled in the world for uniformity of character and massive ness; and a top of shale and sandstone, 5000 to 23,000 feet thick. This mass has been folded. In a zone 900 miles long and 50 to 125 miles wide, the strata exhibit such attitudes and relations as could result only from a force of compression acting from north west or from southeast, or from both directions. Our problem is :

Jan 1, 1893

By Harold R. Wampler, John L. Bolles, Adrian J. Broderick

Phelps Dodge's 60,000 tpd Morenci Concentrator has been in operation since 1942. The integrating of process control applications into the concentrator began in 1972. A process control system is presently on-line controlling 30 primary grinding circuits and all reagent additions. The system consists of a centralized control room process control Computer, on-stream X-ray analyzer, on-stream particle size analyzers and an operator interface. This paper describes the process control system's development, control concepts and its influence on the concentrator performance.

Jan 1, 1978

By Fred Van Covern

Before getting into a discussion of the subject of my paper, I want first to make it clear to everyone that I am speaking as an individual; and that any expressions of opinion that are contained herein, or may be expressed in any oral discussion that may follow its presentation, are entirely my own, and must not be construed to be the official opinion of the American Petroleum Institute. Demand fob Motor Fuel, 1936 During the year just closed the domestic demand for gasoline exceeded 481 million barrels. This compares with 434,810,000 bbl. consumed during 1935 and indicates an increase of 10.46 per cent. Export shipments amounted to 27,831,000 bbl. while in 1935 they totaled 30,613,000 bbl. Total demand, therefore, was 509,422,000 bbl., or 9.16 per cent above the 465,423,000 bbl. of 1935. Following are the figures for several years: Already we are supplying gasoline domestically and as foreign shipments at a rate almost 25 per cent greater than our low level of 1933. Before giving figures for 1937, I should like to spend a moment or two in discussion of gasoline inventories, from the point of view of minimum working stocks and other requirements and of probable actual levels. Inventories of Gasoline The year 1936 closed with about 62,900,000 bbl. of finished and unfinished gasoline in storage—about 6 million barrels more than was on hand

Jan 1, 1937

By Richard A. Mullins, James J. Merle

Systematic sampling and analysis in coal-washing plants results in product control and economical operation. A well-organized laboratory system reduces operating costs and increases sales if the operating and sales companies make full use of information it supplies. The operating cost of a control laboratory is less than 1 pct per ton of coal produced.

Jan 5, 1950

By Arthur Taggart

A GENERAL awakening of interest among mill men concerning the mechanical efficiencies of their crushing machines is evident from a perusal of the recent files of mining publications. Considering the large part of the power bill which must be debited to the crushing department, such. interest is natural. When, however, the articles on the subject are read, the only statement upon which the writers agree is that fine grinding consumes a large amount of power, and that the machine which, from a concentration standpoint, offends as a slime producer is, for that reason, a serious offender in wasting power. When the mill man attempts to find a method for measuring the power wasted, or to compare the efficiency of one machine with that of another for the same work, he is confronted with a choice of methods which lead to conflicting results. There are two reasons why the work of crushing is not more generally understood. In the first place, experimental data are difficult to obtain; and in the second place, before these data can be put in general form certain assumptions must be made. A difference in these assumptions by different investigators has led to conflicting conclusions. This conflict has resulted in the proposal of two laws. The first of these is the so-called Rittinger's law, which is variously stated as follows: . "The work of crushing is proportional to the reduction in diameter."-R. H. Richards: Ore Dressing, p. 304 (1903). "The Work required to crush rock is very nearly proportional to the reciprocals of .the diameters crushed to."-A. Del Mar: Engineering and Mining Journal, vol. xciv, No. 24, p. 1129 (Dec. 14, 1912). "The Work done in crushing is proportional to the surface exposed by the operation, or better expressed for this purpose, the Work done on a given mass of rock is proportional to the reciprocal of the diameter of the final product, assuming that all the mass has been reduced to one exact size, which is only theoretically possible."- A. 0. Gates: Engineering and Mining Journal, vol. xcv, No. 21, p. 1039 (May 24, 1913).

Jan 1, 1914

By H. Van F. Furman

TO those engaged in the purchase and sale of gold- and silverores, mattes and bullion, the frequent differences in the gold- and silver-contents, as reported by different assayers, is a source of much annoyance and expense. The desirability of uniform methods of assay has long been recognized by certain refiners who specify in their bullion-contracts the method to be adopted in assaying the bullion. One large producer of base bullion employs at each refining-works with whom it has a bullion contract an assayer whose duty it is to see that the bullion is sampled and assayed according to contract-specifications. For the assay of gold- and silver-bullion, standard methods are now generally adopted; the reeult being that differences seldom occur. While we cannot hope for anything near perfection from fireassay methods for ores, mattes and base bullion, as carried out cornmercially, such methods may be made to yield results which answer all commercial requirements, and they will probably be retained for obvious reasons. The object of the present paper is to point out some of the sources of error and to show the importance of more uniform methods of assay and close attention to the details of the work. The sources of error in the assay of ores and mattes are: improper sampling; losses of the precious metals during fusion, scorification and cupellation; imperfect elimination of the base metals on the cupel and imperfect extraction of the silver during the parting in nitric acid. It is not the object of the present paper to enter upon the subject of sampling; but a few remarks may be of value. There has been considerable discussion recently in Colorado upon the frequent differences which occur in the assays of Cripple Creek gold-ores, and these differences have been attributed to various causes. The writer is informed by two of our most prominent smelters that since they have adopted 100-mesh screens (the general practice is 80-mesh) the

Jan 1, 1895

By Erland Johnson

BRINE was discovered at Avery Island, La., in 1790, but it was not until 1862 that rock salt was found about 13 ft below surface-the first discovery of rock salt on the continent. Maximum elevation of the island is 152 ft and elevation at the shaft 31 ft. The mining level is 530 ft below elevation at the shaft and the shallowest salt about 12 ft below surface. A shaft was sunk in 1869 when the mining operation started. In 1898 the present shaft was sunk, and the mine has been operated by International Salt Co. ever since.

Jan 6, 1957

By H. R. Aldrich

This paper presents some of the results obtained during the field season of 1919 while mapping, in detail, the stratigraphy of the Gogebic Range in Wisconsin. The detailed stratigraphic section for the range was first published, in 1919, by W. 0. Hotchkiss,1 State Gcologist of Wisconsin. The idea of the continuity of the definite succession thus established was the result of underground work in the productive part of the range in Michigan and Wisconsin, where most of the required data also were obtained. The bulk of the range in Wisconsin is heavily covered by drift; in fact, there is but one satisfactorily exposed section across the entire formation, few partial sections, and only scanty outcrops of any size. Evidently mapping of the detailed members of the formation could only be established at a few points; and if from these small areas the .unexposed portions were to be mapped by projection, the only apparent method for projection was straight-line interpolation modified or supported by data from the scanty outcrops and from test workings. It was found that by tracing a magnetic line, the position of which in the formation may be determined from test pits and outcrops, the projection of that member through the drift-covered areas can be accomplished. The magnetic line serves as a datum horizon within the formation to which reference may be made in correlating outcrops and ledge matter thrown from test workings. The foot wall is easily located also, and from the two datum horizons thus available and the known proportional thickness of the several members in the type sections, outcrops and artificially exposed ledges can be correlated by lithological characteristics. As a result, the tracing of magnetic lines became the basis of our work on the stratigraphy and we were able to carry the mapping of detailed members throughout the length of the range. It was found that the magnetic horizon at the base of the Tyler slate was most easily followed by the dip needle; that discontinuity caused by cross-faulting could be established; that folding along the strike could be detected in a repetition

Jan 1, 1922

By J. C. Marquardt L., J. A. Bratt, J. P. Hunt

The Quebrada Blanca copper/molybdenum prospect lies on a dissected plateau in the high Andes of Northern Chile. The Superior Oil-Falconbridge Group began exploration of the Property in 1977 under a joint venture foreign investment agreement with the Chilean government. Quebrada Blanca is a relatively high grade secondarily enriched porphry copper deposit. Primary mineralization occurred 38 million years ago and accompanied quartz monzonite intrusive. Early disseminated Primary mineralization was followed by hydrothermal mineralization, mineralized breccia, and post-mineral faulting. After supergene enrichment Quebrada Blanca was buried under late Tertiary gravels and then partially re-exposed in Quaternary time. During the past five years, a successful exploration program has developed an open-pit mining reserve, provided samples for bulk metallurgical testing, and located more than adequate supplies of water for future operations. The main orebody is amenable to conventional metallurgical treatment and contains more than 400 Mt (441 million st) of recoverable open-pit ore at about a 1:1 overall stripping ratio. The average millhead grade during the first six years of operations will exceed 1.5% Cu, plus recoverable molybdenum values. Several hundred million tons of additional reserves are available in the surrounding districts

Jan 1, 1984

By K. A. Natarajan, I. Iwasaki

Electrochemical measurements were made wing chalcopyrite and pyrrhotite electrodes in aqueous solution containing a xanthute collector and ground ore mineral particles. The purpose was to investigate the electrochemical reactivity of ozone with respect to dissolved xanthute, surface adsorbed xanthute, and the sulfide mineral itself. Electro-chemical evidence for the removal of xanthate coatings from chulcopyrite, pyrrhotite, and platinum surfaces by ozone is presented. The oxidizing power of ozone is compared with that of oxygen and other common oxidizing agents to portray the superiority of ozone as an oxidant.

Jan 1, 1986

By Y. J. Wang

A critical path approach is presented for the problem of mine ventilation networks where regulators and fans are employed to control the airflow distribution. The problem is a classic one arising in mine ventilation planning. By identifying the analogy between the network for controlled flow and that for critical path method (CPM), the applications of the well known CPM technique to the ventilation problem become straightforward. The mathematical formulation of the problem is presented and the solutions are illustrated with examples. The cutset operation is introduced and employed for obtaining alternative solutions. The effects of booster fans on the total air power of the ventilation network are also discussed.

Jan 1, 1983

Jan 1, 1920

By Edwin Chance

DURING the past 10 years, the safe and efficient lighting of the coal mines of this country has received an ever-increasing amount of attention. Several States have passed laws attempting to regulate the type of lamp to be used and the nature of the fuel to be burned, and the mining departments of coal-mining States have generally shown a keen and intelligent interest in this subject. The passage of the recent Employers' Liability Act in Pennsylvania has made it necessary for many coal-mining companies to take out liability insurance, and the companies underwriting such insurance have made it desirable for the insured to permit the use of, none but illuminants of established worth. While these conditions have not obtained for a sufficient length of time to permit the statement that the illumination of coal mines by portable lamps has been standardized, still, considerable progress has been made and the direction of future practice in this branch of coal-mining technology is very evident. Under these conditions it seemed that a review of the methods now used in coal-mine illumination, together, with a brief consideration of the principles underlying these methods, might be of some interest. Miners' lamps may be divided into three classes: The open light, the electric cap lamp and the flame safety lamp. It will be desirable to consider each of these classes separately, as each has properties peculiar to itself and one class is hardly comparable with another. In this country, without question, the open light is the most generally used of all miners' lamps. This fact is explained by the relative freedom of a large proportion of our mines from gaseous conditions, and by the admirable systems of ventilation installed in those that show a tendency toward such conditions. In the metal relines, the miner's candle has had and still has considerable vogue. Because of the small amount of ventilation usually supplied in metal mines, the freedom of the candle from any tendency to produce noxious gases or offensive odors, and the small amount of air it consumes, are. valuable assets, while, because

Jan 2, 1917