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By Roy Lindgren

Since the year 1643, when the first blast furnace in America for treating iron ore was built at Saugus, Mass., out of mica schist quarried in the neighboring district, the procurement of a suitable refractory for furnace lining has been a problem of concern to the operators of furnaces. The stacks built of mica schist continued to smelt iron ore until about 1836, when, according to F. H. Norton, the first firebrick were produced1, at Queens Run, Pa. Other writers speak of brick having been molded and burned in Massachusetts about the year 1834. In 1841, Andrew Russell began to produce medium refractory plastic clay brick near East Liverpool, Ohio, that were used for lining blast furnaces1. The well-known Kentucky clay-producing district was not opened up until the year 1871, but since then it has produced a large percentage of the linings for iron blast furnaces. While some strides have been made by the refractories industry during the 100 years that have passed since the first firebrick were produced, it has been only during the last two decades that any real progress has been made towards bettering the product, even though the method of production had improved. Perhaps the fault lies with the user of the brick rather than with the producer, for not sooner demanding a supe¬rior product. During the past 15 years the tonnage produced per lining has increased from 500,000 gross tons to 1,000,000 gross tons, and now some furnaces are producing 1,600,000 gross tons and better on a single lining. It is true that enlarged capacity of furnaces and improved practice have accounted for some of this increase in tonnage, nevertheless better quality in firebrick must be given credit for its share. However, we are not yet ready to say that we have reached a maximum life of furnace lining. We believe that a better product can be produced and that the refractories industries of America will, through their extensive research depart-

Jan 1, 1936

By Peter G. Chamberlain

Many mining engineers considering in place leaching for the first time are uncertain as to how to evaluate ore bodies for potential leachability. Evidence presented in this report emphasizes the critical role of permeability in such evaluations. Whether an engineer is considering leaching "tight" formations typified by the porphyry copper deposits of the southwest or the permeable uraniferous sandstones of Texas and Wyoming, permeability measurements are the keystone of any testing program. Permeability tests range from cheap and easy to highly expensive and sophisticated operations. Constant head, variable head, and pumping tests all have application in evaluating ore bodies for in-place leaching. Costs of these tests will not unduly deflate the pocketbooks of most mining companies. The basic procedures for selecting and running these field tests--including preparing suitable wells--are reviewed for the benefit of newcomers to in-place leaching.

Jan 1, 1979

By L. G. Austin

The procedure for scaling breakage parameters determined in a laboratory mill to values for a full-scale mill is briefly presented. A simulation model of a closed circuit mill also requires a model of residence time distribution, a mass transfer law to predict over-filling as a function of flow rate through the mill, and a model to describe classification action. For fine dry grinding, or viscous slurry grinding, it is necessary to allow for slowing-down of breakage rates for a fine mill charge. Four examples of comparing simulation models to actual plant data are presented. The first is wet grinding of copper ore in normal closed circuit at 50 tph (metric) production, under conditions where the mill does not overfill. The second is the wet grinding of copper ore in reversed closed circuit at production of 87, 102 and 108 tph, with flow through the mill of approximately 150, 200 and 300 tph. The third is dry grinding of coal with a hot air sweeping stream to remove all of the coal as air-borne material, in open and normal closed circuit. The fourth is grinding of cement clinker in a two-compartment, air-swept tube mill in normal closed circuit with two different classifiers, producing 120 tph of 3250 Blaine cement. In all cases the simulated capacities and product size distributions were in reasonable agreement with actual plant performance.

Jan 1, 1984

By P. Barnes

THE complete and accurate filtration of water (if the word ,accurate may be thus used) for the feeding of boilers, and for many similar industrial purposes, although somewhat practiced both at home and abroad, has been by no means common. Even if the exact line cannot be defined at which filtration begins to be called for, and will be found profitable, it is certain that in a large number of cases it may be employed with real advantage in the economy of fuel, and also in. the greater durability of the boiler or other form of apparatus in

Jan 1, 1882

By J. V. N. Dorr

DEADWOOD and the Black Hills were familiar names to me from childhood, for. I had an uncle who was among the earliest eastern investors there and I used to hear of the Uncle Sam mine and its rich ore back in the eighties. The spring of my junior year at college, in 1893, brought me an offer of summer work at the Deadwood & Delaware smelter, in Deadwood, and full of the thrill of the long journey from New Jersey, I went out as chemist and stayed four months. Within a week or two of my arrival, I went through the tragic experience of seeing an associate drink cyanide by mistake and die within a few moments. I shall never forget the horror of feeling that my lack of knowledge of an antidote might be responsible for his death, but I found later that the solution he drank was so strong that nothing could have been done. A year after graduation, when I had settled down to chemical research work in New York, an offer came to go back to the smelter in Deadwood, and within a few days I was again tramping down "the Gulch" with my lunch bucket and putting in the standard assay office shift of that day, from 7 a.m. to 6 p.m., with a half-day off on Sundays. During my absence East, the D. & D. smelter had been changed from a pyritic smelter, using native pyrite, and Homestake concentrate to matte the siliceous gold ores, into a copper-matting smelter using copper ores brought from Butte, over the newly-completed Burlington rail-road. The work was interesting, and the laboratory offered many opportunities for making improvements. I remember also undertaking experiments at home on a new method of gold precipitation for the chlorination process and leasing a mine in Strawberry Gulch that promised great things, but soon petered out.

Jan 8, 1927

By Henry A. Ley

Oklahoma produced about 40,000,000 bbl. less crude oil in 1930 than it did in 1929, but developed the largest initial production from current well completions ever recorded in its history. The output of this year would have exceeded all previous years had it not been for state-wide production curtailment. The record initial production of 5,911,982 bbl. from new oil wells completed during the year is accounted for entirely by the rapid development of the Oklahoma City field. Completions declined to the lowest levels since 1909, as a result of a marked reduction in number of dry holes incident to reduced wildcat exploration. Leasing was most active in western and northern counties of the state west of Oklahoma City, but on a much smaller scale than in the preceding year. Geological and geophysical surveys were likewise most active in this western territory. The urge to deeper objectives resulted in the discovery of oil on the Cement fold. Changing economic conditions have created a distress situation among the marginal operators in northeastern localities of the state. Elsewhere in the state production records and successful exploitation of new supplies have been eclipsed by a new social concept of the industry in accord with natural economic developments. Many of the producers of crude oil have organized for a voluntary stabilization of the industry by regulating the output of wells. To enforce their measures these operators have sought for and secured the support of the state. Consequently, the current position of the crude-oil producer is not unlike that of the natural-gas producer—withdrawal of supplies in accordance with market needs. And while the industry as a whole is artificially stabilized by these measures individual operators and some of the integrated concerns suffer hardships. Oil Developments and Production The early operations in Oklahoma were confined to northeastern and eastern localities, beginning in 1885. The first commercial oil wells were completed in 1894, near Chelsea in Craig County, from Cherokee sands in the lower portion of the Pennsylvanian section. Scattered

Jan 1, 1931

By Bension Varon

Systematic projections of mineral supply, demand and prices are an integral part of the mineral sector planning process. As such, their primary value is not as prophecies but as devices for imposing discipline on thinking about the future and as means of ensuring consistency in policy decisions. Both the present and the broad outline of the future as presently discernable affect projections on specific minerals. The present world mineral situation reflects most prominantly the recent commodity cycle while our view of the future is largely shaped by perceptions and attitudes of policy-makers and the public over larger issues. Mineral commodities are of considerable importance to various countries. This in itself dictates a strong interest in systematic projection activities, the need for which is heightened by the volatility of certain basic variables affecting mineral demand in the world. It is useful for presentation purposes to discuss the various techniques suited for projecting mineral trends under three principal headings, viz., econometric modeling, systems analysis and technological forecasting. In addition, two specialized variants, input-output analysis and resource base modeling, are discussed. In each case, a brief description of the approach and some indication of its application to projections of mineral commodities are provided.

Jan 1, 1977

By Charles J. Speake, Dennis R. Haley, Thomas E. Finch

The tremendous interest in development of surface- mineable coal throughout the western US will bring with it a requirement for many manhours spent in mine planning and equipment selection. One problem in particular that engineers face during the planning stage is that of selecting a dragline with the proper reach capability. Reach, expressed in terms of operating radius and effective spoil radius, can be a major problem when mining deeper than originally planned, and aside from production requirements, the ability of a particular dragline to spoil across a strip is essential. Determination of dragline reach needed for a multiple-seam western coal operation can be simplified by use of an equation derived below that eliminates the need for tedious and repetitive calculations.

Jan 5, 1977

Mark Twain once observed that "Everyone complains about the weather but nobody does anything about it." Not too long ago, the same observation held true for the problem of air pollution. During the past 25 years, however, the mounting concern over air pollution has spurred industrial and governmental research to find ways and means to combat the menacing situation. But for all the time and money spent in recent years to fight it, air pollution is still a major problem in most industrialized communities in America. At the SME Fall Meeting last September, coal's responsibility for such pollution was aired at an informative panel discussion moderated by Ernst Hall. The many-sided problem of air pollution became readily apparent as five experts, representing industry and government, parlayed over the task of cleaning up dirty air. Their opening comments are reprinted here.

Jan 11, 1964

By C. A. Heiland

THE Eötvös torsion balance permits the measurement of certain second derivatives of the gravity-potential, which are known as the gradients of gravity and the curvature values for an, equipotential plane of gravity. These quantities are influenced on level ground by the configuration of the masses underneath. Hence, the torsion balance has gained great importance for the location of geological structures and thus indirectly for the discovery of oil and other mineral deposits. If the ground is not level, however, the measurements become more difficult, because the superficial mass-irregularities also produce more or less considerable disturbances. It is necessary, therefore, to determine the shape of the surrounding topography by leveling as well as by consulting topographic maps and to compute its influence upon the torsion balance. The correction thus determined is called, in general, the topographic correction; it is composed of two constituents, the terrain correction and the cartographic correction. The terrain correction would be that part of the topographic correction as derived from the direct leveling of the area surrounding the station, whereas the data for the computation of the cartographic correction are obtained from a topographic map, usually beginning with a radius of 100 meters, as under most circumstances it is difficult to level along a larger concentric circle about the station.

Jan 1, 1928

By C. A. Heiland

THE Eötvös torsion balance permits the measurement of certain second derivatives of the gravity-potential, which are known as the gradients of gravity and the curvature values for an equipotential plane of gravity. These quantities are influenced on level ground by the configuration of the masses underneath. Hence, the torsion balance has gained great importance for the location of geological structures and thus indirectly for the discovery of oil and other mineral deposits. If the ground is not level, however, the measurements become more difficult, because the superficial mass-irregularities also produce more or less considerable disturbances. It is necessary, therefore, to determine the shape of the surrounding topography by leveling as well as by consulting topographic maps and to compute its influence upon the torsion balance. The correction thus determined is called, in general, the topographic correction; it is composed of two constituents, the terrain correction and the cartographic correction. The terrain correction would be that part of the topographic correction as derived from the direct leveling of the area surrounding the station; whereas the data for the computation of the cartographic correction are obtained from a topographic map, usually beginning with a radius of 100 meters, as under most circumstances it is difficult to level along a larger concentric circle about the station.

Jan 1, 1928

By H. T. Clark, S. Feigenbaum

THE importance of measuring the temperature of molten steel in the open-hearth furnace has been recognized for many years. Poor temperature control may be costly to steelmaking operations and lead to a lowered quality of the steel. Low or excessive temperatures may shorten the life of the furnace, ladles and molds. Rates of reactions in the furnace and efficiencies of deoxidizers are known to change materially with a change in the temperature of the metal and slag. Ladle skulls and mold and stool stickers cause steel to be scrapped instead of being converted into useful products. Finally, the structure, segregation and surface condition of ingots are affected by the teeming temperature. Mill investigations of the effect of bath temperature upon steelmaking operations have been largely qualitative in character, based upon observations by practical melting men. The physical chemist has used the empirical information available and has reached reasonable and useful conclusions with respect to the various melting processes. The introduction of a reliable direct- reading pyrometer will permit accurate quantitative evaluation of the effects of temperature and should furnish a more rational basis for study of the thermo- chemistry of steelmaking. The problem is not merely one of making a small number of temperature measurements in the open-hearth furnace. This has been done by several methods to a degree of precision that was apparently satisfactory. Considerable effort by a number of investigators has been directed rather to the development of an open- hearth bath pyrometer that would be both accurate and practical for routine measurements. To be practical, the pyrometer should be inexpensive to operate; that is, the installation, operating and maintenance costs should be exceeded by the tangible benefits to the open-hearth operator. Temperatures from 2800° to 3100°F. are encountered in the open-hearth furnace. The surface of the molten metal is covered by several inches of slag, which prevents direct observation of the metal surface for optical or radiation measurements. Both slag and metal are highly reactive at these temperatures and will attack to a greater or lesser extent any material immersed in them. Adequate protection of thermocouples, which of necessity must be brought to the temperature of the bath, has generally resulted in a large, heavy assembly made up of .brittle materials, unsuited for handling on the open-hearth floor. The lie of the equipment was short and maintenance was an important consideration. EARLIER WORK Any one of a number of physical proper- ties of liquid steel could conceivably be used as a basis for temperature measurement. Efforts to the present time, however, have been confined largely to measuring either the thermal electromotive force generated between two dissimilar materials immersed in the steel or the intensity of radiation from the surface of the steel. These

Jan 1, 1946

By Sam Tour

Some years ago, the writer described heat checks or thermal cracks that occur in die-casting dies.' The life of dies was considered in relation to. the casting temperature, the material used for the die and the heat to be absorbed by the die per unit volume of casting made. The mechanism of the action that results in thermal failure of dies was described. In the present paper the writer proposes to describe some additional observations in regard to heat checking, make one or two suggestions as to the method or methods for further attack of the problem, and give the results obtained on some work carried out along these lines. Importance of Heat Checking Heat checks in steel are the source of trouble in many industries besides that of die casting. Every shop where metals are subjected to hot working is searching for improvement and hoping for a cure. The development of a material of sufficient strength to be used as a die and yet devoid of the property of heat checking would be a godsend to many shops and many industries. The need for thorough study and research on the subject is evidenced by the wide variety of hot-working die steels on the market. It is peculiar, but true, that in practically every case the maker of the steel can give concrete evidence to prove his contention that his type of hot-working die steel is as good as or better than any other. A number of steel companies have several hot-working die steels from which choice can be made to fit a particular set of requirements. Possibly to expect one material to be universally the best hot-working die steel is unreasonable. In some hot-working operations, as in drop forging, the die must have great toughness to withstand the stresses developed; in other operations, as in hot piercing or punching, resistance to erosion at high temperatures, possibly defined as strength and hardness at elevated temperatures, is required. In still others, as in die casting, only sufficient hardness to resist scoring between moving surfaces is required, whereas the resistance to sudden changes in temperature must be at a maximum.

Jan 1, 1935

By Sam Tour

Some years ago, the writer described heat checks or thermal cracks that occur in die-casting dies.' The life of dies was considered in relation to. the casting temperature, the material used for the die and the heat to be absorbed by the die per unit volume of casting made. The mechanism of the action that results in thermal failure of dies was described. In the present paper the writer proposes to describe some additional observations in regard to heat checking, make one or two suggestions as to the method or methods for further attack of the problem, and give the results obtained on some work carried out along these lines. Importance of Heat Checking Heat checks in steel are the source of trouble in many industries besides that of die casting. Every shop where metals are subjected to hot working is searching for improvement and hoping for a cure. The development of a material of sufficient strength to be used as a die and yet devoid of the property of heat checking would be a godsend to many shops and many industries. The need for thorough study and research on the subject is evidenced by the wide variety of hot-working die steels on the market. It is peculiar, but true, that in practically every case the maker of the steel can give concrete evidence to prove his contention that his type of hot-working die steel is as good as or better than any other. A number of steel companies have several hot-working die steels from which choice can be made to fit a particular set of requirements. Possibly to expect one material to be universally the best hot-working die steel is unreasonable. In some hot-working operations, as in drop forging, the die must have great toughness to withstand the stresses developed; in other operations, as in hot piercing or punching, resistance to erosion at high temperatures, possibly defined as strength and hardness at elevated temperatures, is required. In still others, as in die casting, only sufficient hardness to resist scoring between moving surfaces is required, whereas the resistance to sudden changes in temperature must be at a maximum.

Jan 1, 1935

By J. B. Newkirk

IN 1939 Bitter and Kaufmann1 suggested that iron, precipitating from a copper-rich, Cu-Fe solid solution, appears initially as coherent particles of r-Fe which transform to the body-centered-cubic form of iron when the alloy is cold worked. Since then there has been considerable discussion, supported only by indirect evidence, regarding the validity of the concept. For example, Reekie, Hutchison, and Hether-ington2 interpreted the changes in electrical resistance accompanying the aging of Cu-Fe specimens in terms of a coherent 7-Fe precipitate which transformed to the incoherent a-phase during long aging or cold working. Greninger- ound that Cu-Fe alloys which had been water quenched from 1050" and then held at 650°C for 3 hr changed from weakly to strongly ferromagnetic as the aged wire was subsequently cold worked. He also found diffraction lines corresponding to body-centered-cubic iron in Debye-Scherrer patterns given by aged and worked specimens but lines corresponding to only one face-centered-cubic phase in specimens which had been aged but not worked. Knoppwost,' and later Cech and Turnbull,5 found that aged Cu-Fe specimens showed a slight increase in ferromagnet-ism after they had be? cooled in liquid nitrogen. Very recently Denney6 followed the kinetics of the precipitation reaction as indicated by the saturation magnetization, hardness, and diffuse X-ray effects. The experimental results reported by all of the authors mentioned above are readily explained in terms of the Bitter and Kaufmann concept. However, most of the evidence is indirect when used to define the structural changes involved. It was the aim of the present investigation to determine the mechanism of precipitation of iron from a Cu-Fe solid solution in the light of available published information and with additional new and more direct experimental data. Experimental Method At 1060°C copper will contain up to 3 atomic pct Fe in equilibrium solid solution.7 The solvus slopes rapidly toward lower iron concentration, so that at 600°C only about 0.5 pct Fe remains in solution at equilibrium. Below the eutectoid temperature (850°C), the iron-rich phase in equilibrium with the copper-rich solid solution consists of body-centered-cubic a-Fe. Above 850 °C the equilibrium iron-rich phase is face-centered-cubic r-Fe. The alloy to be studied was made by melting electrolytic iron and OFHC copper by induction under vacuum in an Alundum-lined crucible. The metal was held molten for about 5 min, after which time the power was turned off and the crucible was tipped about 70" to promote directional solidification. The resulting ingot, containing 2.5 wt pct Fe by analysis, was clean, large grained, and free of gross segregation. Slices % in. thick were cut from the ingot, rolled to 1/8 in. in thickness, homogenized in hydrogen at 1060°C for 24 hr and, finally, quenched in cold water. Specimens for all subsequent tests were made from these slices. Squares measuring about 1 cm on a side were cut from the slices to make specimens for studying hardness and microstructure. Wires (0.020 in.) for the Debye-Scherrer survey were drawn from 1/8 in. sq rods which had been cut from the homogenized slices. Large crystals for observing diffuse X-ray diffraction effects were prepared by mechanically

Jan 1, 1958

By H. L. Ames, P. H. Jennings, R. W. Stanley

A process has been developed for leaching copper, lead and calcium from molybdenite concentrate. The leachant is a solution containing an oxidizing chloride (e. g., CuC12, FeC13) and an alkaline earth metal chloride (e. g., CaC12). Cupric chloride and ferric chloride, in the presence of 20-30% calcium chloride, are effective oxidants for chalcopyrite and galena. Calcium chloride, in addition to promoting the rate of leaching, serves to lower the solution pH and raise the boiling point. Leaching for two hours at 110'~ with a 1 % CuC12-10% FeC13- 30% CaC12 solution results in the extraction of up to 98% of the copper in molybdenite, 98% of the lead, and 79% of the calcium. Less than 0. 5% of the molybdenum is dissolved. The leach solution can be rapidly and effectively regenerated with gaseous chlorine and recycled. Build-up of copper and lead in the leach solution is controlled by discarding about 30% of the leach solution each cycle.

Jan 1, 1973

By Jon Kogut

This paper describes three programs, currently in use within MSHA, for graphic analysis of accident frequency data. The first program, TREND, plots confidence bands for curved trends in data compiled over a period of time. In addition to detecting statistically significant upward or downward trends, the program can be used to determine whether an observation at a particular time deviates significantly from the historical pattern. The second program, POIPORP, plots interval estimates for the risk of accident in each of several environments, given an observed number of incidents and exposure time at each environment. POIPORP is designed to quantify the uncertainty implicit in incidence rates based on limited information and to facilitate statistically valid comparisons among the rates. The third program, CINDY, plots dynamically adaptive control charts for accident or injury experience at a given location. These charts are used to detect statistically significant departures from a changing standard or a previously established trend. All three programs are written in FORTRAN IV, utilizing DISSPLA and IMSL. They exemplify forms of statistical analysis that would not be practical without a computer. Use of the programs is illustrated with applications to coal mine fatality and injury experience.

Jan 1, 1983

By George H. K. Schenck

The investment analysis methods that are most generally accepted in the mineral industries in the mid-80's are presented along with their advantages and disadvantages. Also covered are current widely-used practices for introducing the uncertain nature of most of the important variables in an investment analysis, which is contrasted to the former dominance of deterministic analysis. Finally, the discussion turns to current practice for handling the two critical areas: cost of capital and inflation. The advice contained is reinforced with data from a survey of current practices in the petroleum industry.

Jan 1, 1985

J. C. WRIGHT.-The problem of organizing and maintaining a vocational class for those employees who are engaged in the mining industry depends on several most important factors. The first is the sympathetic cooperation of employer and employee; the second is to find the subject matter that must be presented to these men; and the third is to find the instructor who can present that subject matter. This is perhaps the most difficult, for we usually find a man who knows the material that is to be presented but is not a teacher or does not know how to organize his material. The man must know the subject matter from the standpoint of absolute contact with industry in order to be a successful teacher. I have come into contact with two kinds of schools organized in connection with mining occupations. In one type the instruction leans very largely toward elementary subjects, arithmetic, reading and writing and spelling; it is not of such a character as to help or improve the working man in his occupation in the sense that we are attempting when we speak of vocational education. In the other type of school, an engineer is usually employed as a teacher. He immediately begins to give the things with which he is most familiar and the instruction becomes such as only those who possess a high-school or college education, perhaps, are able to receive. In between these two schools is the school we are trying to, promote, a school that will meet the needs of those employed. MARGUERITE W. JORDAN,* Altoona, Pa. -Vocational education has become the business man's problem; for he is the keeper of that white elephant, labor turnover, and anything that will decrease the size of the monster is worthy of serious consideration. This vocational education can do; for it can supply many of those deficiencies in upbringing and. environment that make for the discontent and restlessness of our varied classes of unskilled labor: the Anglo-Saxon mountaineer; the Southern negroes who have crossed Mason & Dixon's line by the thousands, "searching satisfaction for our minds;" and the still greater number who have sought across the sea America, "the promised land.

Jan 4, 1919

By J. Landau, A. Dim, R. Houlihan

Recent developments in the application of solvent extraction in hydrometallurgical processing make it desirable to reassess the present state of availability of suitable equipment for these applications. The range of solvent extraction applications now includes very large scale applications with a modest demand on separation performance (the treatment of some base metals) and applications in which the decisive factor is a very high requirement on separation performance. The extraction column to be described in the present paper is of the type in which mechanical energy is provided for the two- liquid system inside the column. The active elements for this are reciprocating sieve plates designed and mounted so as to uniformly load the driving mechanism, to eliminate vibration of the plant, to have sufficient control over the degree of dispersion of the dispersed phase, and to reduce axial mixing effects, which are highly detrimental to the separation performance of production-scale plant. The operating features of the reciprocating-plate column will be illustrated mainly by experimental results obtained on a 4" diameter column in the extraction of uranyl nitrate with TBP. Some mechanical features of the operation of reciprocating-plate columns will also be discussed.

Jan 1, 1973