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By Colin C. Harris, Nathaniel Arbiter

The flotation operation can be analyzed in terms of three groups of variables. The first, largely independent of control by the operator, embraces the fixed physical and chemical properties of the ore minerals. The second includes all chemical and physical effects imposed on an ore after mining that influence its floatability. These can be either purposefully or accidentally applied. The third embodies the flotation-machine characteristics which realize the potential floatability of selected ore minerals in terms of grade and recovery levels. The machine effectiveness thus depends not only on its own contribution, but on the prior influence of all other variables on floatability. HISTORICAL DEVELOPMENT From the earliest days, flotation mills used many types of machines. Hoover 20 in 1914 mentioned as then important the Potter-Delprat tank for gas generation by acid, the DeBavay cones for skin flotation, the Elmore mixer and separation chamber for vacuum flotation, and his own modification of the Mineral Separation cell for the agitation froth process. Less important at the time were the MacQuisten tube and the Hyde cell. By 19274~ scores of machines had been developed and dozens had found their way into mills. From then on, however, under the scrutiny of competitive tests, many fell into disuse. Taggart in 19454~ classified processes broadly as skin flotation and froth flotation, dividing machines for the latter into the three categories: bubble column, pulp body, and combination.* Under 'bubble column' he listed all pneumatic, cascade, and subaeration cells; and under 'pulp body' those cells in which gas was generated by boiling, chemical action, and pressure reduction, as well as the agitation-froth type. At that writing skin flotation, the cascade machines, and all pulp body and combination machines were said to be extinct, leaving pneumatic and subaeration types dominant (u. S. practice). The process of elimination has continued to the present, with almost all pneumatic cells succumbing to the pressure of competition from subaeration machines. The only new machines to appear in recent years have been double-impeller types f and these have met with only limited acceptance.

Jan 1, 1962

By Edward Steidle

It has been said that "the command of nature has been put into the hands of man before he knows how to command himself," and what we see about us gives particular emphasis to this observation. If this condition be granted, the vaunted boast of school and college, of the institution that had the training of this generation, and of its fathers, and of its grandfathers, the boast that education is a "preparation for life," stands exposed as a hollow claim, or as a ghastly, cynical conception of life, or else education has fallen far short of its intentions. It has been evident for some time that education was not meeting the fullest expectations of society. In recent years there has been a deal of speculation indulged in by both laity and faculty in regard to American education and American civilization, and some few and sporadic changes have been effected. Today, however, there is no longer time for mere hypothetical considerations; we are faced with certain definite facts and confronted with obvious conditions that will not wait for fine-spun theories. If educators do not put their house in order, someone else will do it for them. The trends in mineral industries education must be in harmony with this general realignment that is today visible on the educational horizon, and only as these trends are in conformity with this movement can they be called sound. Two questions, then, confront mineral industries educators: (1) What are the trends in mineral industries education, and (2) how do these trends correlate with the major educational movements of the day? Scope or Mineral Industries Education Before launching into these particulars, it might be well to define the scope of mineral industries education and to consider its present position. Mineral industries education embraces three main types of work: 1. Earth Sciences and Geography.—Geology, mineralogy, geography— courses basic to all mineral industries and to the humanities. 2. Mineral Engineering.—Mining, petroleum and natural gas—dealing with mineral producing industries. Application of earth sciences and all types of engineering to exploitation of natural mineral resources.

Jan 1, 1934

By Franklin Moeller

Considering the really short time that has elapsed since hydro-metallurgical processes of extracting copper from ores have been extensively developed, and the large scale on which this method is practised at Ajo, the successful operation of the plant must excite the admiration of every visitor. The application of the mechanical unloader to the purpose for which it is employed at Ajo is but an extension of the use for which it was originally designed, some 20 years ago, for unloading iron-ore vessels at the lower lake ports. At a time when the maximum output of a single machine, with men shoveling the ore into buckets, did not exceed 40 tons per hour, G. H. Hulett invented and constructed a mechanical unloader with a bucket of 10-ton capacity. This machine was of the steam hydrauIic type, and it is still in operation after nearly 20 years of service. Several more machines of the same type were built, but the difficulties of power transmission, and the rapid development of electrical machinery, soon led to the adoption of electrically operated machines, and practically all of the later installations have been thus equipped. This electrically operated unloader has proved so well fitted for the work that the design of the lake boats has been practically revolutionized, with special view to the ease and rapidity of unloading. It is now possible to unload a 12,000-ton vessel with four machines in a little over 2 hr. This has necessitated an increase in the capacity of the machine, and the largest yet built handles an average load of 17 tons, with a possible maximum of 20 to 21 tons. The Ajo excavator is somewhat simpler in design than the iron-ore unloader, in that it is not provided with a larry. In the unloader, the iron ore, picked up by the bucket, is delivered to a larry or transfer car which runs in the lower chord of the bridge; the larry then delivers the ore either into railroad cars, standing on several parallel tracks, or into the stock pile, thereby saving the time that would be required for the bucket to make the trip. At Ajo, the bucket delivers the tailing

Jan 1, 1920

By A. C. Fieldner, W. A. Selvig

Ash in coal has always becri regarded as an undesirable substance, as the heat content of a coal dccreases in direct proportion to its ash contcnt. It represents so much inert materid that has to be transported, handled when the coal is burned, and finally disposed of. W. R. Roberts, in an address bcfore the Engineers' Society of Western Pennsylvania, Pittsburgh, on Sept. 29, 1925, said that on an annual output of five hundred rnillion tons of coal, a reduction of 3 per cent. of ash means fifteen million tons of refusc and a decrcase of $30,000,000 in freight charges. Ash also often prevents effieient utilization of the coal through the formation of clinker causcd by the mcltirig of the ash constituents when subjected to heat. The mineral constituents of coal may be of such nature as to make the coal unsuited for speeifie uses as for instance, high-sulfur coal for making metallurgical coke. While the usual proximate analysis of coal gives the amount of ash, it gives no information as to the nature and coniposition of the ash nor of the minera1 constituents from which the ash is produced. For the efficient washing of coal to remove ash-forining constituents it is desirable to know the composition and distribution of the ash-fonning constituents. Obviously such information is also desirable for the most efficient utilization of coal. Nature and Composition of Coal Ash Coal ash may be defined as the inorganic residue remailning after cornplete ignitior of coal. It is dcrived from the mineral constituents of thc coal. The ash-forming constituents may be roughly classified as inherent impurities and extraneous impurities. The former are mixed intimately with the coal substance, and arc derived either from the original coal-forming material or from external sources such as sedimentation and preeipitation while the vegetal coal-forming plant remains accumulated. The latter are present in the coal bed as partings, bands or nodules of pyrite! slate, shale, calcit,e, bone, etc. These are formed either during the laying down of the coal bed, or subsequently. Flag-

Jan 1, 1927

By Paul Tyler

FULLY a decade ago, demand for ground mica began to exceed supplies of scrap mica from manufacturing operations and of waste block from feldspar and sheet mica mining in the United States, with the result that in recent years the market has absorbed larger and larger quantities of mica recovered as a by-product from clay washing,1 as a joint product with kyanite,2 and by grinding schists. So far, only schists that contain a large percentage of mica have been utilized for making ground mica, but already there has been a good deal of wishful thinking with regard to recovering mica as an aid to the prospective working of low-grade gold ores and ores of certain base metals. With wet-ground mica selling at $60 to $100 a ton and even dry-ground mica worth over $20 a ton, many ores that could not be considered as otherwise workable under present conditions will show commercial possibilities if they can be made to yield even a relatively small percentage of salable mica. An interesting paper might be written on the coming role of industrial minerals as joint products of metal mines, It is largely a matter of mar-kets. Many years ago I watched the mess left behind the gold dredges in the mountains of Colorado and thought of the Denver sand and gravel operators who prided themselves upon their canniness in providing devices for catching gold merely as an incident to their regular business of selling what we miners classed as "tailings." Nowadays almost every milling or mining operation near settled communities finds use for at least part of its waste for road material or concrete aggregate and several eastern iron mines have gone into the crushed-stone business. Promoters now mention fertilizer "filler" as potentially salable at all the way from $1 to $10 a ton, or whatever is needed to cover costs of mining and treating the "ore" and leave the metal values as "clear profit." In emulating the pork packers in their efforts to utilize "everything but the squeal,"

Jan 1, 1938

BIRINGUCCIO was born in Siena in 1480, the son of Paolo and Lucrezia di Bartolommeo Biringuccio.* He was baptized on October 20 of that year with the given names Vannoccio Vincenzio Austino Luca. His father appears to have been an architect, for in 1504 he was paid 600 scudi for his work on the walls of the Communal Palace and at the same time he was superintendent of streets for the city. The course of Biringuccio's life followed closely the checkered fortunes of the Petrucci family of Siena. A warm supporter of Pandolfo Petrucci, Biringuccio did not falter in his allegiance to the family and their party during his lifetime. It was probably to the protection and patronage of this lord that he was indebted for the opportunity to travel widely through Italy and into Germany during his early years and so to lay the foundation for the extensive knowledge of the subjects he was to describe in the Pirotechnia. In 1507, as he himself indicates (p. 48), he was 'in Friuli and. Carnia in northern Italy after having traveled in Germany,, and he also visited the, brass, works in Milan. After returning to Siena; he was sent by Pandolfo to direct the iron mines in near-by Boccheggiano. When Pandolfo died in 1512 (in which year Biringuccio's s father also died), Biringuccio continued to support the Petrucci family in the person of Pandolfo's son, Borghese, who succeeded, to the rule. Under his patronage, Biringuccio was appointed to a post in: the Armoury of the Siena Commune in 1513. In ISIS a popular uprising forced Borghese and his followers, including Biringuccio, to flee from Siena. Biringuccio and the goldsmith Francesco Castori, head of the mint, were accused of having debased the coinage alloy with the knowledge and consent of Borghese. When he failed to appear in 1516 to answer these charges-which may well have been invented by the opposing political faction-Biringuccio was declared a rebel and was exiled as a traitor to the Republic. He then traveled about Italy, was in Rome and Naples, and visited Sicily in 1517.

Jan 1, 1942

By A. J. M. Ross

BACKFILLING of stopes and other underground openings in the Homestake mine with sand tailings was undertaken primarily to reduce surface subsidence, which was wrecking much of the surface plant and a substantial part of the town, and to make possible maintenance of openings into the top of pillar stopes as mining progressed. The progress of this type of filling has been rapid and the results very satisfactory. Sand is now used in filling timbered stopes, shrinkage stopes, and abandoned drifts and crosscuts. A permanent pipe-line system for transporting sand tailings into the mine by gravity has been installed. The close filling of all stopes has resulted in important benefits other than the two major ones. The ore bodies in the Homestake mine occur as replacements in one distinctive layer of the metamorphosed pre-Cambrian sediments along a group of minor folds that together form a complex anticline that pitches at 35º to 40º to the southeast. The ore bodies are extraordinary for their magnitude. Widths of over 300 ft. have been mined and continuous ore has been followed for over 1200 ft. along the strike on some of the upper levels. Mining has been by shrinkage stoping with square-set mining of crowns and pillars. In the standard plan, shrinkage stopes 60 ft. in the direction of strike and the full width of the ore have been taken up to within 25 ft. of the level above. After filling, the crown has been mined by square-set methods, as have also the 40-ft. pillars between shrinkage stopes. In former days, when the supply of ore seemed inexhaustible, the mining of pillars was allowed to lag far behind because of the high cost. Many pillars were rather badly fractured on the level and in some places between levels. Coarse waste was used for backfilling all stopes, but in pillars it became increasingly difficult to maintain haulageways for the transportation of this fill over the top of the stopes as mining progressed The cost of maintaining these crosscuts was excessive and in many pillars practically impossible. Therefore it became the practice to fill pillar stopes by tapping the back and sides of the stopes.

Jan 1, 1939

By S. Harries Daddow

THE INSUFFICIENCY OF PILLARS OF COAL FOR THE PURPOSES DESIGNED-THE FRUITFUL CAUSE OF DANGER, EXPENSE, AND WASTE-THE PROOF OF INSECURITY-SUBSTITUTE FOR PILLARS OF COAL-PILLARS AND PANELS COMPARED. PILLARS of coal, which are designed and left in our mines as the means of supporting the overlying strata of our coal-beds, and securing protection to the miner, are not only insufficient for these purposes, but the most objectionable means of providing the desired security to life and property. Though such pillars are left at a great sacrifice to the owners of collieries and mineral lands, loss to the resources of the commonwealth, and ultimate privation to the public, they defeat the very ends for which they are designed, and not only do not secure life and property, but are as fatal to the one as ruinous to the other. Propositions.-It is eminently desirable that the resources of the commonwealth-particularly our mineral wealth in anthracite coal, which is limited-should be carefully utilized and made available, not only to ourselves but our posterity. Yet, speaking as an anthracite miner, we are wasting our resources of coal with a recklessness which will bring ruin in the end, unless checked, not only to the iron manufacturing interests of the East, whose chief protection, in competition with the iron-masters of the interior, lies in a cheap and abundant supply of anthracite furnace fuel, but to the best interests of the State. It is, consequently, not only desirable, but necessary, that we should realize every ton of coal from each colliery, and every acre of coal area, in order that our resources may not be wasted at present, to breed want in the future, and to realize the greatest present benefit to the mine, the miner, and the public. It is not possible, however, to secure these ends, if we continue to leave, as we do at present, from one-third to one-half our resources in anthracite as pillars in our mines. But our sad bills of mortality, our abandoned collieries, and our yawning mountain-sides, present ample evidence that even this enormous waste of coal, though left for the purpose of protecting life and property, is as totally inade-

Jan 1, 1873

By Haakon Styri

In discussion of Dr. Fitterer's paper on electrolytic separation of slag inclusions, some results from experiments on electrolyzing high-carbon steels at the SKF Research Laboratory were given. l We had been working for a number of years on chemical methods of separating the inclusions but could not find any solvent that would dissolve the steel without attacking some of the inclusions, particularly the sulfides in which we were mostly interested at the time, nor any that would dissolve all sulfide or silica in filings as fine as 300 mesh without attacking the iron. Electrolytic methods had also been tried without any real progress until we learned from the Bureau of Mines about the use of the collodion membrane around the anode. Our early difficulties were to some extent different from those of the Bureau of Mines, perhaps because of experimenting on steels of higher carbon content, but most of our difficulties were of the same nature as those of the Bureau. Formation of large quantities of basic hydroxides was traced to the use of impure and oxidized ferrous sulfate. To protect from oxidation from the atmosphere during electrolysis, after purer chemicals were obtained, a thin layer, 54 in. or less, of molten paraffin was poured over the surface of the cathode liquid, where it solidified. It was found desirable also to hold the cathode chamber slightly acid by initial addition of 0.1 per cent acid (sulfuric or hydrochloric) to prevent precipitation of the hydroxide. This acidity would decrease gradually and the cathode chamber would become neutral before the end of the electrolyzing. The increase in acidity in the anode chamber during our early experiments had appeared to cause attack of the precipitated sulfides in the residue, which originally was analyzed by volumetric method for sulfur, and for this reason a 10 per cent sodium citrate solution was substituted for the sulfate in the anode chamber. With the use of the more reliable Eschka method for sulfur determination (as in coke), there was however no serious attack on the sulfides in the anode chamber with a variety of different liquids, as shown in Tables 2 and 4. The Eschka method gives a higher sulfur value than

Jan 1, 1933

By P. K. Foster, C. M. Payne, A. McNabb

Some measurements of the rate of loss of hydrogen from cylinders of iron and steel are analyzed in terrns of a trapping theory. The apeement is encozcraging and gives rise to estimates for the density of traps in the metal. Furthermore, the results appear to be consistent with the assumption that the diffusion constant D for the steady flux of hydrogen through iron lies on the extrapolation of the linear curve (log D us 1/T) obtained at higher temperatures. IT has been shown in a previous paper1 that the literature relating to hydrogen diffusion in steels contains sufficient evidence to invalidate the application of Fick's laws to hydrogen diffusion in steel at low temperatures. To account for the deviations from simple diffusion behavior a trapping theory was developed, and the fundamental laws modified accordingly. In the present paper, new data on the evolution of hydrogen from long cylinders are presented, and together with some published data are examined in terms of the requirements of the theory.' Properties of solutions of the basic equations derived previously1 and appropriate to the present experimental conditions are outlined in the first section as they determine the form in which the experimental data must be presented for a comparison of theory and experiment. Two new solutions not previously reported have been derived as described in the Appendix. The experiments and treatment of data are then given in Sections 2 and 3 and the results are discussed in Section 4. 1) THEORETICAL CONSIDERATIONS The hydrogen-diffusion theory1 applied in this paper postulated that lattice-dissolved hydrogen at a concentration C diffuses randomly in accordance with Fick's first law, but that the lattice contains a uniform density N of traps which can capture and delay hydrogen atoms. kC atoms are trapped per second in a region containing unit concentration of vacant traps while p are released per second in a region containing unit concentration of occupied traps. On this basis it was shown (Eq. [30] of Ref. 1) that, when local changes in the lattice-dissolved concentration C are slow enough for equilibrium to be established with the traps, the system is represented in dimensionless form by the equation:

Jan 1, 1965

By Paul M. Tyler

Fully a decade ago, demand for ground mica began to exceed supplies of scrap mica from manufacturing operations and of waste block from feldspar and sheet mica mining in the United States, with the result that in recent years the market has absorbed larger and larger quantities of mica recovered as a by-product from clay washing,1 as a joint product with kyanite12 and by grinding schists. So far, only schists that contain a large percentage of mica have been utilized for making ground mica, but already there has been a good deal of wishful thinking with regard to recovering mica as an aid to the prospective working of low-grade gold ores and ores of certain base metals. With wet-ground mica selling at $60 to $100 a ton and even dry-ground mica worth over $20 a ton, many ores that could not be considered as otherwise workable under present conditions will show commercial possibilities if they can be made to yield even a relatively small percentage of salable mica. An interesting paper might be written on the coming role of industrial minerals as joint products of metal mines. It is largely a matter of markets. Many years ago I watched the mess left behind the gold dredges in the mountains of Colorado and thought of the Denver sand and gravel operators who prided themselves upon their canniness in providing devices for catching gold merely as an incident to their regular business of selling what we miners classed as "tailings." Nowadays almost every milling or mining operation near settled communities finds use for at least part of its waste for road material or concrete aggregate and several eastern iron mines have gone into the crushed-stone business. Promoters now mention fertilizer "filler" as potentially salable at all the way from $1 to $10 a ton, or whatever is needed to cover costs of mining and treating the "ore" and leave the metal values as "clear profit." In emulating the pork packers in their efforts to utilize "everything but the squeal," mining engineers may go too far; on the other hand, they should not let

Jan 1, 1942

By A. J. M. Ross

Backfilling of stopes and other underground openings in the Homestake mine with sand tailings was undertaken primarily to reduce surface subsidence, which was wrecking much of the surface plant and a substantial part of the town, and to make possible maintenance of openings into the top of pillar stopes as mining progressed. The progress of this type of filling has been rapid and the results very satisfactory. Sand is now used in filling timbered stopes, shrinkage stopes, and abandoned drifts and crosscuts. A permanent pipe-line system for transporting sand tailings into the mine by gravity has been installed. The close filling of all stopes has resulted in important benefits other than the two major ones. The ore bodies in the Homestake mine occur as replacements in one distinctive layer of the metamorphosed pre-Cambrian sediments along a group of minor folds that together form a complex anticline that pitches at 35" to 40' to the southeast. The ore bodies are extraordinary for their magnitude. Widths of over 300 ft. have been mined and continuous ore has been followed for over 1200 ft. along the strike on some of the upper levels. Mining has been by shrinkage stoping with square-set mining of crowns and pillars. In the standard plan, shrinkage stopes 60 ft. in the direction of strike and the full width of the ore have been taken up to within 25 ft. of the level above. After filling, the crown has been mined by square-set methods, as have also the 40-ft. pillars between shrinkage stopes. In former days, when the supply of ore seemed inexhaustible, the mining of pillars was allowed to lag far behind because of the high cost. Many pillars were rather badly fractured on the level and in some places between levels. Coarse waste was used for backfilling all stopes, but in pillars it became increasingly difficult to maintain haulageways for the transportation of this fill over the top of the stopes as mining progressed. The cost of maintaining these crosscuts was excessive and in many pillars practically impossible. Therefore it became the practice to fill pillar stopes by tapping the back and sides of the stopes.

Jan 1, 1940

By Willard Ide Pierce

CONSIDERING the extent of the gold-fields of Nova Scotia, which occupy an area of 6000 to 7000 square miles, a few words as to the cost of extracting and reducing the ores may prove of interest. The veins are for the most part narrow, 4 to 12 inches being the usual width, while a 2-foot vein is considered a large one; but they offer many advantages, inasmuch as the ore is easily treated, wages are low, and machinery and supplies can be transported by water to within from 1 to 15 miles of the different mining districts. The Salmon River vein is a notable exception to the above rule as to width. It ranges from 4 to 20 feet in width. The Hall-Anderson of Fifteen-Mile Stream (where there are several veins) is another, which has proved to be from 3 to 4 feet in width. The ownership of all mining claims is retained by the Crown, but persons wishing to work them can lease as many unoccupied areas as they please for twenty-one years, with option of renewal, on the payment of two dollars for each area, and a royalty of 2 per cent. on all gold extracted. Each area consists of 150 Get along the lode and 250 feet across, upon which a certain amount of work must be done, which by recent law is reduced from one hundred to forty days' work for each area every year. Any person erecting in a district the first mill, having at least 8 stamps, and being at least 10 miles from any other mill, is entitled to a lease of 10 areas, free from advance-payment and from royalty, for twenty-one years. A record must be kept, and filed every quarter at the office of the Commissioner of Mines, of the total number of days' work done on the areas, and a monthly statement of the number of tons crushed, and the actual yield of gold. Gold-mining in Nova Scotia may be said to have commenced with the finding of a nugget of gold in a brook at Tangier in 1858. The following table, taken from the official report," gives the total yield

Jan 1, 1885

By Carl Floe

A NUMBER of proposals have been made for the hydrometallurgical recovery of copper from flotation concentrates, but as yet no process has been developed that has demonstrated an ability to compete with the present smelting methods under ordinary conditions. The treat-ment of copper concentrates by hydrometallurgical methods is in general similar to that used in the present electrolytic zinc process and involves roasting, leaching with H2S04 solution, separation of solutions, control of impurities and electrodeposition. While many of these steps are simpler and more readily carried out for copper than for zinc, a number of inherent difficulties have prevented the general adoption of the process. To compete with smelting, the following problems must still be con-fronted, although many solutions for their have been proposed: (1) con-duction of the roast in such a way that leaching will give an extraction of copper comparable to that obtained by smelting; (2) regulation of the ferric iron content of the solutions during electrolysis; (3) disposal of the excess acid regenerated from the sulphates formed in roasting; (4) eco-nomical recovery of the precious metals from the leach residues. The roasting problem is largely one of preventing the formation of copper ferrites, CuO.Fe2O, and Cu20.Fe2O3, which are quite insoluble in dilute sulphuric acid. These ferrites are apparently formed' to a small extent even at low temperatures and above 650° C. their formation is rapid1. While it is possible to carry out laboratory roasts in such a way that less than 5 per cent of the total copper is present in the insoluble ferrite form, a closer temperature control is required than can readily be obtained in industrial furnaces. The flash" roasting effects and consequent high temperatures that occur as the calcine falls from hearth to hearth in the ordinary multiple-hearth roaster are probably largely responsible for the inevitable formation of some ferrites. The result is that in a commercial plant the extraction of copper would not average more than 90 per cent in a single 10 per cent H2SO4 leach. This is

Jan 1, 1937

By C. P. Sandberg

C. P. Sandberg, London, Eng. 1 think we should all be grateful to the Pennsylvania Railroad Company, and to their chemist, Dr. Dudley, for spending so much time and money in order to solve an important question; nor are me less indebted to the public spirit which leads them to impart tlie experience thus gained. In Europe nothing similar has hitherto been done, either by a company or by any private individual. In England the great railway companies employ their engineers in other ways, and do not keep a chemist or specialist to study rails; bat even if they did they would probably not publish the results. The chief professional engineers are so occupied with their private practice of railroad construction generally, that they cannot be expected to devote their time and energies to so special a question. The German Railway Union has, in my opinion, missed the real object of its elaborate researches by falling into the error of specifying costly, impracticable tests for rails—tests at the same time which do not infallibly expose the impurities that may be in the rails under examination. There has, therefore, been nothing done on this side of the Atlantic in the way of exhaustive study to determine the best composition for steel rails. America should consequently have full credit for the enlightened example which she has set. I wish, however, to make a few remarks on Dr. Dudley's second paper,—& paper which follows very much upan the same lines of argument as the first red three years ago, upon which I have previously touched in my pabr on the same subject read at the meeting in August last. If Dr. Dudley had discovered a new metal he could hardly, I think, have taken wore pains to prove that he was correct in his first formula for the best chemical colnposition of steel rails. But I hare seen so much done in the way of proof by experiment that I am inclined to think that almost anything can be proved by experiments and by satnples. If Dr. Dudley would only give up his formula, which would not suit any country—not even America—

Jan 1, 1881

By N. Lilienberg

Refractory materials play much the same part in the producion of metals as houses and shelter for men, and it therefore seems useful to discuss sometimes the ways of manufacturing them. In fact, it appears to me that too little has been said on this important matter, probably because the manufacturers of fire-brick do not care to publish details for the benefit of competitors, but perhaps, also, by reason of the indulgent indifference of consumers. Judging from the revolutions in the manafacture of iron and steel caused by using calcareous materials for the furnace-bottoms, it does not seem improbable that in the future basic bricks may be produced suffciently strong for building also side-walls and arches, and perhaps, also, for use in blast-furnaces. But the existence of the present difficulties of great shrinkage in burning and small strength against compression, which limit the possibility of using basic bricks to Bessemer converters and such open-hearth furnaces as permit the bottom to be separated from the superstructure, seems to indicate still a long and extensive use of silica fire-bricks. I am not prepared to say anything about American fire-brick making, but knowing that industries abroad are watched with increasing interest by American manufacturers, I have imagined that this association would like to hear some facts about the way firebricks arc made in my country—Sweden. Well-known as it is that Sweden produces a high quality of iron, it is perhaps not so universally known that the same country produces a very high grade of silica fire-brick, whereby most of its own wants are supplied. In giving the following sketch I can, of course, not claim that all the facts are entirely new, but shall consider my object attained if American manufacturers can derive some benefit from the comparison of the following methods with their own, and if some discussion on this important subject can be aroused which will contribute to further progress. In order to show the extensive use of domestic fire-bricks in Sweden, where English bricks are easily obtainable, I mention the fact that about twelve millions of all kinds of fire-bricks (reduced to

Jan 1, 1885

By Charles E. Stuart

A paper on this subject can cover but a limited range. A thorough visualization of the subject would contemplate a comparative analysis of haulage machines and batteries of various types; the relationship of the storage-battery locomotive to other types of mine haulage should be considered and limiting factors in each case should be carefully developed. This paper will deal briefly with these factors. So far as the writer has been able to determine, the first storage-battery locomotives for mine haulage were manufactured in 1897 or 1898 and were tried out in the Pocahontas coal field, but they were not sufficiently satisfactory to justify their continued use. Battery explosions were frequent and caused serious damage to the wiring, electrical equipment, and the clothing and bodies of the motormen. Sulfuric acid was used as the electrolyte. Experiments were then conducted with locomotives bearing reels of flexible cable through which connection between the motors of the locomotive and the trolley wire was maintained. At first, these reels were turned by hand. Later, the reels were revolved by contact with the wheels of the locomotive, being raised out of contact with the wheels, by a lever, when necessary. About 1902, the plan of operating the reel, by chain and sprocket wheels, from one of the locomotive axles, as is still the practice, was devised. The popular floating motor-driven reel had its inception in the Pocahontas fields prior to 1906. The maximum radius of operation of the reel-type locomotive is about 500 ft. (150 m.) from point of connection with trolley wire. This is ample for room work and certain entry work, but the need for a machine that would operate entirely independently of the trolley wire was so great that, with the development of the storage battery, renewed efforts were made to manufacture a successful storage-battery locomotive. About 1908, the gasoline locomotive was introduced. In spite of many objections to this type of machine for such work, the fact that hundreds of these machines were purchased was proof of the need for a machine operating independently of the trolley.

Jan 1, 1923

By B. H. Dunshee

This paper is not intended to be a technical discussion of square-set framing as used in mines, but merely a short description of the different kinds of framing that have been used in the Butte mines, and what has been decided upon, after years of practical experience, as being the best, taking into consideration the physical condition of the veins and country rock, and also the supply of timber available for mining purposes. Butte is, essentially, a square-set district. Virginia City, Nev., was the first mining camp to use this method of timbering, and to Philip Deidesheimer, who went to the Ophir mine in 1860, is given the credit of solving the problem of square-set framing, where large bodies of ore were stoped and the timbers were supposed to hold the ground from caving without any filling. That he did his work well is shown by the fact that the main features of his framing are in use to-day. In the Butte mines the conditions are such that this method of timbering is generally used. We do not, of course, depend upon the timbers any more than is necessary. The worked-out stopes are filled with waste rock as close behind the miners as possible and not interfere with mining operations. The waste rock is obtained from development work on the different levels or from the surface. In the earlier days of mining in Butte there were numerous independent companies and naturally there were different ideas as to the best way to frame the square sets, although the general features were the same. Timber was abundant for mining purposes and the common practice was to use sawed lumber, generally 10 by 10 in. or 12 by 12 in. square. Some of the mines used for girts 6 by 10 in. or 8 by 12 in. timber, depending upon whether they used 10-in. square or 12-in. square timber for posts and caps. This avoided the necessity of framiug the ends of the girts, and also required less timber for the

Jan 1, 1914

By T. A. Wright

THE SAMPLING of waste materials containing copper, lead and tin has taken on a new significance within recent years, and is of increasing importance, on account of the entry of some of the copper refineries into this field and the tendency towards consolidations among the smelters. In the past, such material was sold on the basis either of a rough or grab sample or of casual inspection of the lot. The two principal sources of this waste are the processes of fabrication and the scrapping of automobile, electrical, plumbing, railroad and other equipment. In both cases much material can be sorted, salvaged and sold by classification and grade to be melted "as is" or with the addition of new or virgin metal. The increasing care in classifying exercised in the large manufacturing plants tends to increase the proportion of this usable scrap; on the contrary, the increasing use of more complex and special non-ferrous alloys tends to make sorting and grading more difficult in turnings, borings, clippings, etc., and consequently is making sampling of more moment. In tin, lead, aluminum, and zinc furnace by-products such as ashes, drosses, skimmings, etc., the trade practice of evaluation has not varied much. For instance, tin drosses, battery lead, and aluminum skimmings are ordinarily sold on what is called' "metallic button" or "metallic recovery" or "metallic yield." Copper and lead waste, however, is being sold more and more on actual copper and lead contents based on sample and chemical analyses. This paper will be devoted chiefly to the sampling of materials suitable only for refining and recovery of one or more of the metals present. The methods described are often based on the fact that but one metal, such as copper, is to be paid for. The loss of volatile constituents in melting does not appreciably affect the final copper result, as the "after-melting" assay can be readily calculated to the "before-melting" basis, but if smelter efficiency continues to increase, so that in time zinc, for instance, may be recovered on a paying basis, the method of sampling dirty brass, for example, will have to be changed also.

Jan 1, 1928

By G. H. Clevenger

The reagents now used in flotation consist of various acids or salts, which may be either electrolytes or non-electrolytes, dissolved in water and some substance or combination of substances which function as collecting or frothing agents. At times the only dissolved salts present are those naturally occurring in the water used. The general effect of the electrolyte is to greatly sharpen the separation between the gangue and the concentrate. Examples of this are: The use of sulphuric acid with zinc ores; and of sodium carbonate or calcium oxide (lime) with silver-gold ores. Crude pyroligneous acid is also sometimes used when avail able. Various oxidizing agents, such as permanganates, bichromates, etc., are added in the selective flotation of lead-zinc ores. Many other reagents for performing certain specific functions, either real or imaginary, have been proposed, and a number of them have been tried upon a working scale. The wild orgy of experimentation which is now going on in flotation exceeds even that which followed the introduction of the Washoe process for the treatment of Comstock ores, when, among other things, sage-brush tea and tobacco juice were reagents added to the pans. Out of all this will, of course, eventually come a more or less standard practice for the treatment of each class of ore. Omitting a discussion of the functions of frothing and collecting agents, the reagents used in flotation for this purpose may be classified under five general heads: (1) Essential oils; (2) fixed or fatty oils; (3) alcohols and their combinations with organic acids; (4) coal tar and its refined products; (5) petroleum and its refined products. A flotative agent of some kind is required in flotation as now practiced. A single reagent, as, for example, certain of the essential oils, may perform the dual function of frothing and collecting agent, or a mixture of substances may be required. In this country, the essential oils used have been wood products, and have been almost exclusively confined to the steam-distilled pine oils. At the present time, the supply of these is limited, and the cost almost prohibitive, so that their use has been dispensed with as far as possible. The oils and tars resulting from the destructive distillation of

Jan 1, 1917