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By Leonard P. Colvin

Like all successful American enterprises, the mining industry is constantly trying to increase production, lower costs and improve working conditions. Companies are, of course, intensely interested in new equipment to help them gain these important ends, and one recent development-the mechanical raise climber--contributes to all three goals. Properly used, it increases production, cuts costs and has a number of important safety aspects all of which are the subject of this article.

Jan 1, 1962

By C Gunther

Mining examinations are of several kinds and the scope of the investigation depends in each case upon the purpose for which the examination is made. A formal examination of a developed mine is an expensive undertaking; from one to several months are allowed for the work according to the size of the property; many samples are taken; investigation is made of the geological features, including, perhaps, a topographical and geological survey of the surface; the metallurgical treatment of the ore is studied; finally, a determination of costs is demanded. Formal examinations are made for prospective purchasers or as a basis for the consolidation of several properties, and occasionally, in the owner's behalf, to verify the work of resident engineers, or to determine the readiness of a mine for equipment and the kind and capacity of equipment it shall receive. A formal examination of a mine should not be undertaken until a preliminary examination has shown that it is justified. It is regrettable that some engineers are in the habit of prosecuting long and exhaustive examinations of properties whose lack of merit should be, and perhaps is, apparent from the start, or of continuing their investigation long after an unfavorable result is seen to be inevitable. This wasting of a client's money is a species of trickery difficult to prove, and therefore the more contemptible. Preliminary examinations are precisely what the term implies, and are undertaken to determine the advisability of making

Jan 1, 1932

By J. C. McDonald

A DDITIONAL experimental data are presented in this note on a phenomenon which has been touched on but lightly in the literature. The common magnesium base rolling alloy (AZ31B) contains about 3 pet A1 and 1 pet Zn. When cold rolled, it hardens until it starts to break up in the rolls at 30 to 50 pet reduction. When it is heated after rolling to full hardness, it softens. However, other magnesium alloys have shown themselves capable of being cold rolled indefinitely, provided the ratio of roll diameter to starting gage is sufficiently high. As measured by the tensile test, these alloys actually soften when the reduction becomes large (60 to 90 pct). A subsequent heating at 300' to 500°F can produce hardening of this metal. Heating at higher temperatures (600' to 800°F) causes recrystalliza-tion and softening. Menzen' has shown that a magnesium base alloy can be cold rolled without intermediate anneals as much as 90 pet. The alloy studied, Mg-1.5 pet Mn, softened considerably between 20 and 90 pet reduction, as measured by tensile properties; a decrease in yield strength of 30 pet, and an increase in elongation from 3.2 to 16.7 pet (longitudinal direction of the sheet). However, Menzen gives no data on the reaction of this metal. to heating. Ansel and Betterton2 and Hurst and Hatch3 report a similar effect in Mg-1.5 pet Mn-0.1 pet Ca. Their data show an initial hardening, followed by softening. The former authors also show that the alloy softened by cold rolling will harden when heated at low temperatures, and that these effects are absent in Mg-3 pet Al-1 pet Zn. In the course of work4, 5 some years ago, the author observed similar effects with alloys containing cerium, thorium, or zirconium; but not with elements like aluminum, silver, or zinc. Table IA contains the results of an experiment which shows these effects rather well. A binary alloy with 0.3 pet total rare earths (Mischmetal* added) was rolled hot to 1/16 in. and then annealed to full softness by heating 30 min at 800°F. Rolling was continued at 1.5 pet per pass to 80 pet total reduction on 8 in. diam rolls. The metal was harder after 20 pet work than initially but, at 80 pet reduction, properties were back to their original values. Heating for 1 hr at 450°F produced about the same hardness whether the reduction was 20 or 80 pet. At intermediate reductions, the metal hardened, but not to as high values. Extensive cold rolling may also be carried out on metal hot rolled at temperatures sufficiently low to produce a semihard temper. Mg-0.6 pet Zr was rolled to 0.1 in. at 700° to 800°F, 30 pet per pass. As shown in Table IB, a further cold reduction of 85 pet, at 1.5 pet per pass, definitely softened the metal.

Jan 1, 1959

By Frederic K. Bunton

The smelting plant of the British Columbia Copper Co. at Greenwood, B. C., now closed because of the decline in the price of copper due.to the European war, is of special interest to metallurgists for several reasons. It was successfully smelting in blast furnaces the lowest grade copper ore of all plants in America. In order to do so, it had to run at very hig~; efficiency, which necessarily required a large tonnage per square foot of hearth area, together with the minimum amount of labor and other costs. The furnaces smelted daily 2,250 tons of ore (6.62 tons per sq. ft. of hearth area), carrying 0.85 per cent. of copper, at a smelting cost of 81.18 per ton. The entire plant required 130 men to operate it and keep up repairs, showing a labor efficiency of about 17.5 Dons per man per day. In the present paper, the method of obtaining these results is shown. Most of the information contained in this description I obtained as Assistant Superintendent, during the two years preceding the present shutdown. Other sources of information to which I am indebted are: The British Columbia Copper Co., Ltd., by ALfred W. G. Wilson, in The Copper Smelting Industry of Canada; Greenwood Smelting Worlrs, by J. E. McAllister, Engineering and Mining Journal, vol. xci, pp. 1011 to 1015 (May 20, 1911); and Description of the Copper Smelter of The British Columbia Copper Co., by W. L. Bell, in Transactions of the Canadian Mining Institute, vol. xvi, pp. 151 to 154 (1913). II. Location and Connections The smelter of this company is about half a mile south of GreenGood, in the Boundary district of British Columbia, on the Columbia & Westerg branch of the Canadian Pacific Railway. It was originally built in 1900 by Paul Johnson, to handle 600 tons of ore a day in two small furnaces of 300 tons capacity; but in 1907 the old furnaces were torn out, the plant was remodeled, and three blast furnaces, 48 by 240 in. at) the tuyéres, were installed. In 1910, two of these were enlarged to 51 by

Jan 1, 1916

By Prof John E. Church

It is a well-known fact that under similar conditions a ton of pig iron can be made from any ore with less fuel when charcoal is used than when coke or anthracite is employed for heating. The cause of this superiority is entirely undiscovered, and no explanation has yet been offered which has won even temporary acceptance. Such as they are the hypotheses heretofore presented are of two general kinds, and they come from those two divisions of the working force which are so often antagonistic in all professions, the scientific and the practical men. The theory of the scientific men is drawn from the chemical reactions which are known to go on in the furnace, and it is well expressed in a recent paper by Prof. Akerman, of the Stockholm (Sweden) School of Mines. It makes the superiority of charcoal as a fuel in the blast furnace to depend upon its quick and thorough reduction of carbonic acid. This property belongs to charcoal in virtue of its porous structure. Its cells have a diameter of only one twenty-four hundredth of an inch, and one grain of charcoal has been computed to have a surface of two and four-tenths square feet. According to the theory in question, carbonic acid is formed by the first impact of the air upon the fuel; but in charcoal furnaces the acid is immediately reduced to oxide by taking the necessary amount of carbon into combination, and the gas reaches its highest reducing power even in the near vicinity of the tuyeres. Coke, being harder, does not produce so strong a reducing gas in that part of the furnace. Carbonic acid is formed as in the case of charcoal, and remains longer before its reduction to oxide is completed. Anthracite is the

Jan 1, 1879

By H. Shaw

IT is now generally recognized that the gravitational method of geophysical surveying is a valuable aid in elucidating the geological structure of the subsoil and enables the practical geologist to deduce the presence of useful deposits. The particular suitability of the torsion balance to the location of large and important subterranean structures has given rise to a wide application of this method by many of the important oil companies in their search for future supplies, and so intense have been these efforts that little has been heard of the method in other connections, with the exception of occasional references to its application in the location of hidden deposits of metallic ores, salt and lignite, and a number of accounts of its use in the elucidation of geological structures. Its success in the location of salt domes is well known, and establishes it as one of the most important of the geophysical methods, especially for the indirect location of oil. In the British Isles, however, no large occurrence of oil is likely to be revealed, and here the practical application of the gravitational method has been restricted almost entirely to the search for ores. This type of survey possesses well marked characteristics, and presents a gravitational problem that has necessitated the development of a special and probably unusual plan of campaign, full details of which it is hoped will shortly be published. The problems and difficulties encountered in this work are of necessity fundamentally related to those met with in the search for oil by means of the torsion balance, but they also possess several special and distinctive features which undoubtedly differentiate them from the obstacles confronting the oil prospector, and which call for special consideration and treatment.

Jan 1, 1928

By H. H. Rachford, W. P. Schultz

The use of computing machines to solve physical problems has made it imperative to represent physical data in a form computing machines can use. Although curve-fitting is an old and well-practiced art, there still seems to be some interest in questions regarding what methods can be used and why. Even though there are many good references on this subject, it may be of some value to discuss a particular method which has been found to be useful, and to make available the associated tables for its use in the hope that there can be saved a few of the tedious hours necessary to reduce many of the suggested methods to practice. Although a very brief discussion of the mathematical background of the tables is included immediately below, those interested only in their use can skip directly to the section on Use of the Tables. Direct Fit of a Set of Points A frequently encountered problem is: Given data which can be represented by a smooth curve +(x), to find an easy-to-evaluate function F(x), with only a few coefficients, which is a good approximation of +(x) on the interval 0 5 x 5 x,,. Consider F(x) as a linear combination of m + 1 arbitrary, single-valued, continuous, linearly independent functions, f,(x), Ff.r) = a,f,,(x) + a,f,(x) + . . . -+ aifi(x) + If the value of Q(x) is known or can be read from the curve at the points xj: +(x,), +(x,), . . . +(xj) . . . +(x.), and if n = m, then all the coefficients of F(x) can be determined, and F(x,) — +(x,) = 0 for j =. 0, 1, . . . n. This follows from the solution of the set of linear simultaneous equations. +(x<.) = aofu(x,) + aJI(x0) + . . . + a,,f,,(x,) =a, = f,,(x,) + a,f,(x,) + . . . + a,f,,(x,) +(x,,) = a,,f,(x,,) + a,f,(x,) + ... + a,,f.,(x,,) ...........(2) for the coefficients ai. Although the set a, from the solutions of the set of Equations 2 yields an fix) which gives an exact value of $(x,) for the n + 1 points, there is no restraint on ~(xj in the interval xi < x < xj+,. Indeed, if the points +(x,) are not sufficiently smooth, very serious differences may arise between F(x) in the interval and the smooth curve +(x). Least-Squares Fit It has been suggested&apos; that if n is made to exceed m, and the set a, is found to minimize the function the function F(x) is much less sensitive to small errors in +(xi), and usually provides a much better fit to the smooth function +(x). This is known as the best fit in the sense of the least-squares error. To minimize $, set £ = 0,i = 0,1,... iTi,.....(3) The m + 1 equations from Equation 3 are k—n k=n a.^p /,,(a) f,(xt) + a, X A: = 0 k=O k = n k = n k=0 k=0 +(x.) f,(x,),............(4) one equation being obtained for each i = 0, 1, . . . m. Inasmuch as the arbitrary functions f(x) may be evaluated for x,, k = 0, 1, . . . n, and the +(x,) are known values of the curve to be fitted, the simultaneous Equations 4 may be solved for the set a,. Particular Functions Given the functions fi(x) and the set +(xj), the solutions for require evaluating a number of sums of products as well as the solution of an m + 1 order set

Jan 1, 1956

By A. G. Loomis

IT is only within the past 10 years that serious attempt appears to have been made to improve rotary drilling fluids by the application of the principles of colloid chemistry, although the use of chemicals to control the rheological properties of clay slips has long been known in the ceramic industry. The main difficulty apparently lay in the lack of a complete analysis of all of the functions of a drilling fluid in the drilling of the well, together with the lack of adequate consideration of how colloid science could be applied to secure these ends, and particularly how apparent antithetical properties of the fluid could be compromised. Thus one analysis1 of the many requirements of a drilling fluid proved conclusively that the viscosity should be low, in order that cuttings and entrained gas might be eliminated effi-ciently in the settling ditch, while the loss in carrying capacity accompanying low viscosity could be regained by increasing either the density of the mud or the upward velocity of the mud stream in the annular space of the well, and the danger of sticking of the drill stem due to rapid settling in case of enforced suspension of drilling operations could be eliminated by enhancing the thixotropic properties of the fluid. The desired properties of the drilling fluid having thus been established, it was a natural step to treat the fluid with vis-cosity-reducing chemicals, such as salts of weak organic acids1,2-for example, sodium tannate or gallate-and to adjust the pH to the alkaline side to such a degree of thixo-tropy as would give low viscosity and low yield point under the conditions of flow prevailing in the settling ditch, but rapid gelation and high yield point when quiescent in the annular space during shut-downs. In fact, flow in the settling ditch should be just short of turbulent while flow in the well, together with the flow of mud past the cuttings, is practically always turbulent. The use of chemicals other than those mentioned, such as Calgon (sodium hexametaphosphate) and certain other phosphates together with sodium tannate, has now become standard practice and it is the consensus that this method of treatment has proved to be an important step in the development of the art of drilling oil wells.

Jan 1, 1940

By Louis V. Bender, R. E. H. Pomeroy, David H. Browne

E. P. Mathewson, Anaconda, Mont.—After hearing about the success of D. H. Browne with his furnaces, we in Anaconda decided we might venture into the field of pulverized coal for reverberatory smelting. We sent a delegation of investigators to see Mr. Browne and his work, and they returned, filled with enthusiasm, and said they would recommend it strongly.. We thereupon asked for an appropriation, and after some delay obtained the same and fitted up one furnace to use pulverized coal. We copied Mr. Browne&apos;s practice and his selection of machinery for drying and pulverizing coal; and we also copied the burner he used, which was a standard article on the market. We got an expert coal-dust machinery man to design our plant, and were very glad we did so as we avoided some of the unpleasantness that had been experienced at other plants through fires and minor explosions. I want to say, before describing our apparatus a little in detail, that we were quite familiar with the work of Mr. SÖrensen, the pioneer in the use of pulverized coal for copper smelting. Our attention had been called to it by Mr. Klepetko early in the game. And afterward we were familiar with the work done at Cananea by Mr. Shelby. We sent an expert to investigate the question 10 years ago. He examined the work of Mr. SÖrensen; and then went to the cement men and examined their work, and reported at great length that coal dust was the ideal fuel for them, as they took the ash from the coal and sold it as cement. He reported that coal-dust firing could not be made economical in reverberatory copper smelting, and his reasons were that a blanket of nonconducting material would cover the charge in a short time and insufficient heat would reach the charge proper, and we would have floaters over all our furnaces. The flues would be stopped by the dust that did not settle on the charge. We accepted that until our Irish friend got busy and showed us how to do it. Then we built a furnace which we thought was a slight improvement over Mr. Browne&apos;s. We put railroad tracks over our furnaces to draw the charge to the furnace. We had

Jan 1, 1915

By John A. Garcia

A standard set of coal mining laws for the entire United States is hardly practicsble, yet the numerous variations in the state laws for almost every item seems entirely unnecessary. The same useless variations appear in almost every comparable section with no apparent reason except that no attempt has ever been made to codify them, and as they were developed over a long period of time by innumerable individuals and legislatures, the present situation is the logical outcome of lack of cooperation between states. The ventilation of a mine is affected indirectly by many provisions not listed specifically under this heading, so that it would be necessary to tabulate the major portion of all the laws to secure a complete comparable digest; therefore only a few of the more important have been set down here. This point is well illustrated in the section providing for clearance between car and rib, which is intended as a safety measure against personal injury, but is very important from the standpoint of ventilation because of choked airways in mines on two-entry system. Confusing Phraseology Misinterpretation and confusion may be expected from the phraseology alone; one state provides that the scale of the mine map shall be "not more than 100 ft. to 1 in.;&apos;&apos; another state demands "not less than 100 ft. to 1 in." Both probably mean the same thing and seek to prevent the operator from furnishing a map on which the workings will appear SO small that the detail is illegible. Legislation is certainly indefinite that specifies structures must be fireproof when "near" a mine opening, and just what is a "dusty" or "gaseous" mine is open to argument in most of the states. The variation in spacing crosscuts and break-throughs and the limited number of men on a split seem entirely unnecessary, as the distance is not reduced in gaseous fields, excepting in Arkansas and Tennessee, which states produce a comparatively small amount of coal, and the number of men differs 100 per cent. and more for no apparent reason.

Jan 1, 1927

BRADEN, the most southerly of the three big Porphyries in Chile and the first to start production (in 1910), is a remarkable mine. It would be interesting to know just how much it has contributed, and will contribute, to the earnings of the Kennecott Copper Corporation, which acquired 95 per cent of Braden stock in 1915 by an exchange of shares and which subsequently obtained the remainder. Because of this complete ownership no separate annual report is published (as is the case with Anaconda&apos;s South American subsidiaries, Chile and Andes). Income, taxes, operating costs, earnings, and other financial data, including the balance sheet, are consolidated with corresponding items applying to Kennecott&apos;s manifold operations in the United States and other foreign countries. If Braden were in the United States it would be possible to arrive at a pretty accurate estimate of revenue realized each year from the sale of copper simply by applying the average published market price to the production as reported by the company. However, because of the restrictions on sales imposed by the Chilean Government and the almost fantastic regulation of exchange rates in the past, no estimate of the sort would be reliable. This point is illustrated by the following comparison made by Charles R. Cox, president, in Kennecott&apos;s report for 1955: In each year, 1954 and 1955, Braden supplied about 30 per cent of Kennecott&apos;s total copper deliveries; but Braden&apos;s operations contributed 16.7 per cent of consolidated net income in 1955 against only 6.2 per cent in 1954. More will be said later about exchange rates, taxes, and restrictions, and the recent improvement in the situation. Of course another element of

Jan 1, 1957

By W. H. Hoffman

The writer does not claim a right to discnss this subject as a furnace-man or user of iron-ore in this new form. His efforts have been confined to mining, preparing, and separating the magnetic ore from the gangue. Two years&apos; experience in experimenting and another two years in producing concentrates on a commercial scale, have led me to believe that the new trade of making concentrates must be well learned in all of its details. If there have been any partial failures in this most useful branch of the iron business, the failures have been caused chiefly by inexperience or lack of patience. Although I have, within the past five years, constructed machinery

Jan 1, 1892

By P. A. Farrar, M. D. Silver, K. L. Komarek

Thermodynamic properties of Hf-0 alloys have been determined from 0 to 25 at. pct 0 between 1000" and 1200°K by equilibrating specimens with alkaline metal oxide-metal vapor combinations. Partial molar-free energies, enthalpies, and entropies of oxygen have been obtained and are conzpared with similar results for the Ti-0 and ZY-0 In continuation of a thermodynamic investigation of the Ti-O and Zr-O systems1 activities of oxygen and lattice parameters of Hf-0 alloys have been deter- system. The positional entropy in all three systems corresponds to an ideal random interstitial solution with one interstitial site per one metal atom. The lattice parameters of hafnium and Hf-O solid solutions have been determined in the range 0 to 20 at. pct O from measurements of Debye powder patterns. mined. All three metals dissolve large quantities of oxygen to form interstitial solid solutions. The phase diagram of the Hf-O system is shown in Fig. 1.&apos; The maximum solubility of oxygen in the cph a phase is considerable (up to 25 at. pct O). The solubility in the high-temperature phase is much smaller. The only stable compound in the solid state is HfO2 which may exist with a certain oxygen deficiency. The low partial pressure of oxygen of Hf-0 alloys required the application of an indirect method. As the most suitable procedure a method, first applied by Kubaschewski to the V-O system,3 was combined with a principle developed by Herasymenko for the

Jan 1, 1963

By A. E. Back

A method is described in which particulate iron, as distinguished from high purity iron powders used in powder metallurgy, is a precipitant for copper contained in dilute solutions. A new precipitation apparatus utilizes particulate iron precipitants to recover copper more efficiently than is possible in a conventional launder precipitation plant. In the search for lower cost methods of recovering copper from mine water, the use of sponge iron or particulate iron (as distinguished from iron powder used in powder metallurgy) as precipitants in place of tin cans, detinned scrap iron, or scrap iron is an intriguing possibility. The relatively faster copper precipitation rate obtained with particulate iron as compared to scrap iron promises economic and processing advantages when, and if, particulate iron becomes competitive cost-wise with available scrap iron. Kennecott has developed a precipitation cone,&apos; see Fig. 1, utilizing various particulate iron precipitants and has demonstrated the process successfully in a prototype at a flow rate of approximately 1000 gal of solution per min. Essentially complete precipitation of copper is obtained, the cone overflow solution is clear and contains no particulate copper, and the iron factor is more favorable than in a conventional launder plant. Initially, sponge iron produced at the Ray Mines Div. Kennecott Copper Corp. for use in a Leach-Precipitation-Flotation process was used in exploratory tests to develop a suitable apparatus to take advantage of the rapid precipitation rate and efficient iron utilization for the recovery of copper from dilute solutions. Here it was demonstrated that, when sponge iron was added to a launder, the particles of iron collected in the bottom of the launder and tended to cement together. This resulted in incomplete precipitation of the copper and inefficient utilization of the iron. Next, sponge iron was suspended in glass columns to study the dynamics of the precipitation reaction. Again it was observed that the particles tended to cement together at low solution flow rates, while at higher flow rates large amounts of the precipitant overflowed the column, resulting in loss of precipitant and an inefficient process. Next, the precipitant was suspended in an inverted cone in a rising column of solution. Dynamic suspension of the solids was maintained at relatively rapid solution flow rates with instantaneous and complete precipitation of copper and with improved iron utilization. The first tests were conducted on a batch basis and it was determined that a dynamically suspended bed of precipitant was necessary for satisfactory operation. More than 99% of the metallic iron could be converted to metallic copper by careful control of the residence time in the cone and copper precipitation was essentially complete, even when the available iron precipitant was almost depleted. Several cones were built, ranging in capacity from 1 to 200 gal of feed solution per min, and finally, a prototype cone was constructed which was 20-ft high

Jan 1, 1968

By J. J. Becker

BEAN1 has discussed the magnetic behavior of mixtures of small ferromagnetic particles on the order of 20 to l000A in diam. As he points out, there are three size categories with characteristic properties: 1) Particles large enough to contain many ferromagnetic domains magnetize initially by the motion of domain walls. The initial susceptibility of such particles, if domain-wall motion is assumed to be perfectly easy, depends only on their shape. It is equal to the reciprocal of the demagnetizing factor (and is thus 3/4 tt for a sphere) and is independent of temperature. 2) Smaller particles find it energetically undesirable to contain domain boundaries. They are always spontaneously saturated, and reverse their magnetization only by rotation of their entire magnetic moment. As assemblage of such particles has a remanence which is a large fraction of the saturation of the assemblage; its coercive force is on the order of 2K/1,, where K indicates magnetic aniso-tropy from any source, and I, is the saturation magnetization of the substance of which the particles are made. 3) Particles which are still smaller continue to be single-domain, but the direction of their magnetization fluctuates thermally, as first pointed out by Neel.&apos; They have no remanence and no coercive force and possess the temperature-dependent magnetization curve of a paramagnetic substance with a very large moment. Bean calls this superpara-magnetism. All of these kinds of behavior are observable in alloys consisting of a precipitate of ferromagnetic phase in a nonferromagnetic matrix. Fig. 1 shows a typical aging curve for the room temperature coercive force of a sample of 98 pct Cu-2 pct Co alloy

Jan 1, 1958

By John Brown

As a part of a symposium on the relations of structure to ore deposi-tion, in February 1938, the writer presented some tentative opinions derived from his experience with a number of important lead-zinc replace-ment deposits. These ideas were set forth, as a basis for discussion and a stimulus to further inquiry, in a mimeographed leaflet that read as follows: Intimate acquaintance with a number of lead and zinc deposits in metamorphosed limestones seems to indicate the existence of certain common features from which can be established some general principles governing the localization of ore in this type of formation. It is suspected that these principles can be applied, with modifica-tions, to mineralization in unmetamorphosed limestone. In metamorphosed forma-tions, some observed rules are as follows: 1. Bands or masses of pure limestone are very resistant to replacement by ore solutions, and are likely either to contain no ore or to resist replacement until near the end of mineralization. The reason for this apparently is physical, not chemical, since microscopic data indicate that when ore is deposited by far the greater part of it substitutes for carbonate. The chief factor is believed to be a lack of porosity in massive limestone that has undergone flowage and recrystallization. 2. Masses of intensely siliceous or silicated rock are likewise unfavorable ore receptacles. This seems to be accounted for by two factors: (a) chemical unsuit-ability or resistance to replacement, and (b) physical resistance to small-scale brecci-ation, which might facilitate the opening of effective channelways for solutions. Some low-grade ore may occur, however, and also sporadic fracture fillings. 3. The optimum condition for ore reception appears to be found in bands or areas containing carbonate and silicates (or quartz) intimately mingled in something like equal proportions. In this situation movement is likely to result in mixed flowage and fracture, producing a fine-textured porosity that admits solutions freely and provides access to an abundance of replaceable carbonate. Cleavage cracks in some minerals such as diopside are believed to facilitate the penetration of solutions. 4. Certain minerals or assemblages are regarded as favorable impurities in a lime-stone and others as unfavorable. Original quartz, and subsequently developed diopside, and perhaps garnet, are typical favorable pre-ore gangue; in general rather equidimensional, brittle minerals. Tremolite, biotite, and probably wollastonite, are typical unfavorable pre-ore gangue; in general highly elongated and somewhat flexible minerals likely to develop under strong shearing stresses. 5. Tentative opinion is that the ratio of lime and magnesia in a limestone-is of little or no importance.

Jan 1, 1940

By M. Van Siclen

THE outstanding fact in connection with dust disease in the United States at present is the growing recognition of its seriousness by state officials and by the more progressive operators of mining, metallurgical and allied industrial plants. The same may perhaps be said of labor in some of its better organized centers, but the average independent non-union workman continues, as of yore, to suffer the toll of disability and even of death from dust inhalation without realization of the source of his ill-being. Progress in the betterment of the handling of sufferers from dust disease and of the conditions creating dust hazards in mining and allied industries is pursuing a course similar to that of the now widespread campaign against accidents, in which the risk is more obvious, more severe, and was naturally recognized sooner. The coming on of dust disease is generally relatively slow and its immediate effects not infre-quently masked by or attributed to other diseases. Marked exceptions to this general rule have occurred in districts where the dust is particularly pernicious, such as the Rand and Joplin; yet such exceptions, unhappy in themselves, opened the eyes of medical men, and of those in other localities charged with the responsibility for the welfare of industry, to the much more widespread if less spectacular hazard existing from the inhalation of dust in all rock-excavating operations and all industrial operations creating inorganic dust, whether it be crushing and grinding, sand-blast-ing, granite-cutting, or what not. Advancement to date in the United States in prevention and treat-ment has been slow, yet the record shows that quantitative methods for determining the degree of hazard and means for decreasing it were being developed as far back as 25 years ago; and that more rapid progress may be looked for from now on. In 1908, in this country, F. L Hoffman?(1) discussed the mortality from consumption in dusty trades, especially brass foundries; and in 1913 E. R. Hayhurst(2) described the effects of inhalation

Jan 1, 1933

By George Rice

WHEN miners in the interior coal fields of the United States began the practice of blasting the coal without undercutting, or what is known as "shooting off the solid," many explosions resulted, some of them of great extent and &apos;violence, and attended with large loss of life. One of the means adopted for preventing this large loss of life, though not preventive of explosions, was to employ shot firers to discharge the shots when all the other employees had gone out of the mine at the end of the day&apos;s shift. This system still prevails in most of the Central and Southwestern mines. Following the disaster at Winter Quarters mine, Utah, May 1, 1900, in which 200 lives were lost, a system of firing shots electrically from outside and when the men were out of the mine was adopted at the mines of the Utah Fuel Co.1 This system has also been used in France in certain mines that are subject to instantaneous outbursts of carbonic acid gas. These outbursts generally occurred at shot-firing time, on account of the blasts releasing the gas held in crevices under high pressure. The system was also adopted at a number of other mines in Utah, at the Cokedale mine, Colorado, at the Dawson mines, New Mexico, and in some mines of the Tennessee Coal, Iron & Railroad Co. in the Birmingham Ala. district; and more recently in certain mines in Iowa and Kansas. At first there was considerable trouble from misfires, and in a few instances from premature firing, while men were in the mine, through the shot-firing lines becoming crossed with power lines. Fortunately, however, no loss of life resulted from such premature firing within the knowledge of the writers, and latterly this danger has been reduced to a minimum by certain measures of precaution. The proportion of misfires, or failures of individual shots to fire, has also been reduced to a very small

Jan 10, 1914

By Andrew B. Crichton

No more important question has come before the coal industry in the past decade than the prevention of stream pollution by mine drainage; especially in Pennsylvania, where large areas of coal land have been developed. It may be thought that the problem of labor or lack of transportation outweighs in importance that of stream pollution. We can see possible remedies for labor and transportation problems but there is no known satisfactory solution of the mine-drainage problem. The subject has been given little serious attention, for, until recently, it has been little understood; but in the past year it was brought to the attention of the coal-mining industry by the introduction, in Congress, of several bills designed to prevent the discharge of acid waters from mines or other sources into navigable streams, or their tributaries. The first legislation proposed was the Applebybill, H.R.7369, designed particularly to prevent the oil pollution of coastal waters. It contained the following provisions, which the coal men regarded as referring to the coal industry. It shall be unlawful to throw ... any refuse matter of any kind ... into any navigable waters of the United States or into any tributaries of any navigable waters from which the same shall float or be washed into such navigable waters. The chemical, steel, paper, and other manufacturing industries, as well as the mining industry, objected to this clause, the miners claiming that it would prevent the discharge of waste or mine drainage into any waters of the United States, for all streams or tributaries finally reach navigable waters. The next bill introduced was that of Congressman Briggs, H.R. 7430, an amendment to Section 13 of the Pollution Act of March 3, 1899. The original act referred chiefly to oil and oil refuse, but it provided also "that no material of any kind should be deposited on the bank of a navigable water, or tributary, which might reach the waters and interfere with or

Jan 1, 1923

By Carle Hayward

SULPHUR has long been one of the banes of the steel manufacturer and often no effort and expense have been spared in order to reduce it to a small per cent. in the finished product. This condition is clue to a general conviction that in many cases where steels have failed in service, sulphur has been the cause. But there has been a growing feeling in recent years that the verdict against sulphur has been unnecessarily severe. In cases of segregation it was present in augmented amounts along with other impurities, but it had not caused the segregation. High sulphur in pig iron is caused by poor furnace conditions and the sulphur is merely one indication of an iron that has not been properly reduced. No amount of subsequent treatment under oxidizing conditions in the open-hearth furnace can remedy the defects, although the per cent. of sulphur may be considerably reduced. In other words, the causes of bad steel can frequently be traced back to bad pig iron, and sulphur is merely one indication that the pig iron is bad. The writer recently visited a steel plant where a mass of evidence had been accumulated which substantiated this fact, and the superintendent was .emphatic in stating that high sulphur was not harmful provided the steel was not otherwise poor due to insufficient reduction in the blast furnace. The presence of a moderate amount of sulphur is desirable from the standpoint of the man who machines the steel. The low-sulphur material drags and the production of a smooth surface is very difficult. A slight increase in sulphur enables the machinist to produce a smooth surface without difficulty. Since, therefore, such large quantities of steel are subjected to machining, it becomes highly important that the sulphur controversy should be settled, and if its presence is proved to be harmless the ban on it should be lifted.

Jan 10, 1916