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By E. L. Larison

DURING the early years of the present century a notable interest appeared in American industry in the matter of recovering and render-ing profitable byproducts of manufacturing operations. Among the byproducts of reduction of sulfide ores in many plants large amounts of sulfur dioxide gas were available. In certain instances the concentration of S02 in the gases evolved was, or could be made, sufficient to make them suitable for manufacturing sulfuric acid. At the Anaconda Reduction works such a condition existed. Large tonnages of copper concentrate were being roasted and the roaster gases were available and suitable as a source of sulfuric acid. Earlier work on a large scale at Martinez, Calif., and in the Ducktown region, Tennessee, had shown the feasibility of manufacturing sulfuric acid from the S02 contained in gases arising from the reduction of copper sulfide ores. In California and Tennessee the acid found a ready market in manufacture of fertilizers, while the situation regarding disposal of the sulfuric acid was quite different at Anaconda. No local use for acid existed, and a commodity of such low value could not stand freight charges to consuming centers. There was a very large accumulation of sand tailings from the gravity concentration mill below the plant at Anaconda. This material, made by the comparatively crude methods in use up to about 1915, contained about 13 lb. of copper per ton, largely as sulfide minerals. In 1912 serious research work toward recovery of this copper was instituted and after about two years of laboratory and pilot-plant development, a process for accomplishing it was perfected. This process involved roast-ing the sand tailings, leaching the roasted tailings with sulfuric acid, and throwing out the copper by passing the solutions over scrap iron. Under this plan each ton of sand required the introduction of about 70 lb. of 60° Be. sulfuric acid.

Jan 1, 1934

By F. L. Rip, B. C. Haydon

Manganese silver ores are well known to be refractory toward cyanidation. Roasting and sulfurous acid pre-leaching have been suggested for improving their amenability. This paper describes the development and implementation of the sulfurous acid pre-leach process for retreatment of manganese silver tailings at Tonopah, Nevada. The history of the material is summarized and the mineralogy is described. A brief review of an earlier application of sulfurous acid pre-leaching of a manganese silver ore is presented.

Jan 1, 1985

By Svend Rordam

THE development of a cement that will resist the destructive action of sea water and other corrosive waters is a problem that has occupied cement chemists for the past one hundred years. It has been found that of the various salts that commonly occur in corrosive waters, sodium sulphate, magnesium sulphate and magnesium chloride are most destruc-tive to cement. Many investigations have been carried out in the United States, in Canada, and in Europe to solve the problem of what constitutes a sulphate-resistant cement, and during the past 10 years some of the findings give definite information in this respect. COMPOSITION OF CEMENT Portland cement is composed of four major compounds: 1. Tricalcium silicate 3CaO.Si02 (C3S) 2. Dicalcium silicate 2CaO.Si02 (C2S) 3. Tricalcium aluminate 3CaO.Al203 (C3A) 4. Tetracalcium aluminoferrite 4CaO.Al203.Fe203 (C4AF) The two calcium silicates are the main contributors of strength. The tricalcium aluminate contributes some to the early strength of the cement but has the least resistance of the four compounds toward the attack of sulphate waters. The tetracalcium aluminoferrite does not contribute very much to the strength, but is far more resistant to sulphate waters than the tricalcium aluminate. When hardened cement is exposed to water containing sodium or magnesium sulphates, these salts will react with the hydrated tricalcium aluminate in the cement and form compounds that will cause a swelling, disruption and crumbling of the hardened cement.

Jan 1, 1939

By William E. Ford, Edward Salisbury Dana

The important BARITE GROUP is the only one among the anhydrous sulphates and chromates. Mascagnite. Ammonium sulphate, (NH4)2S0,. Orthorhomhic. Usrially in crusts and stalactitic forms. p = 1.523. Occurs about volcanoes, as at Etna, Vesuvlus, etc. Taylorite. 5K2SOa.(N&)ySOd. 111 small compact lumps or concretions. From the guano of the Chincha Islands. Thenardite. Anhydrous sodium sulphate, Na2S04. In orthorhombic crystals, pyrarnidal, short prismatic or tabnhr; also as twins (Fig. 384, p. 160). White, to brpwnish. 0 tically +. p = 1.477. Soluble in water. Often observed in connection with salt lates, as on the shores of Lake Balkhash, Central Asia; similarly elsewhere; also in South America in Tarapaca, Chilc. In the United States, forms extensive deposits on the Rio Verde, Aria. In Cal., at Borax Lake, San Bernardino Co. Aphthitaiite. Arranite. Glmerite. (Ii,Na)&O1. Rhombohedral; also massive, in crusts. Color white. From Vesuvius, upon lava; at DouglashaU near Weateregeln, Ger- many, in hloditc; Stassfurt, Germany; Rocalmuto, Sicily.

Jan 1, 1922

By A. M. Hall

SULPHUR, even in small amounts, may often be harmful to nickel and high-nickel alloys, causing impairment of mechanical strength and destruction of malleability and ductility, as shown by Merica and Waltenberg.1,2 It may act. either in the form of nonmetallic inclusions produced in the liquid state during furnacing or as reaction products resulting from its diffusion into the solid metal. In recognizing the action of this element, ability to identify its various forms by means of the microscope is often of considerable importance, especially when direct quantitative methods are inapplicable. [ ] Of the sulphur compounds associated with nickel and high-nickel alloys, the sulphides that may be found in malleable nickel, Monel? and Inconel? are an important group. These sulphides were investigated by metallographic methods in order to provide descriptive data by which to identify them. The nominal compositions of malleable nickel, Monet and Inconel are given in Table I. The term "sulphide" is employed here in a very general sense, to designate a substance in which sulphur and one or more metallic elements are combined. The term includes any combinations of compounds and solid solutions. METHOD OF INVESTIGATION Three groups of small laboratory melts were made, one group to represent each of the three types of alloy under investigation. Within each group, a number of ingots with a sufficient variety of chemical analyses were prepared so that the effect of each of the elements entering the complete commercial alloy could be isolated and observed. In most cases, to facilitate metallographic study by exaggerating the number and size of the resulting sulphides, somewhat greater amounts of the minor elements were added than are present in the commercial alloys. Likewise, considerably more sulphur was added than is normal, but not enough to complicate the system. Transverse sections were cut at a point one third of the distance from the butt to the head of each ingot, polished and examined with an inverted stage metallograph equipped with a combination polarizing-analyzing vertical illuminator. The light source was a tungsten-mercury vapor arc lamp.

Jan 1, 1943

By William E. Ford, Edward Salisbury Dana

This section includes one distinct group, the Stibnite Group, to which orpiment is related; the other species included stand alone. Pyr., etc. - In the closed tube melts and gives a dark red liquid when hot and a red- dish yellow solid when cold; in the open tube (if heated ver slow? ) sulphurous fumes, and a white crystalline sublimate of arsenic trioxide. B.B. on ciarcoaTburm with a blue Hame, emitting arsenical and sulphurous odors. Soluble in caustic alkalies. Artif. - Realgar is frequently noted as a sublimation product from furnaces roasting ores of arsenic. Crystals are produced when arsenic sulphide is heated in a sealed tube with a solution of sodium bicarbonate. Obs. - Realgar occurs usually in veins associated with silver and lead ores. It has been found in volcanic regions as a sublimation~duct. It has also been noted as a deposit from hot spring waters. It is often rtasociate wlth orplment. It occurs at Felsi5bBnya, Kapnik and NagyAg, Hungary; Allchar, Macedonia. Binnental, Switzerland, in dolomite. In the United States, at Mercur, Utah; in the Norris Geyser Basin, Yellowstone Park, as a deposition from the hot waters. Found at the Monte Cristo millin district, Snohomish Co., Washington: the namerealga7 is from the Arabic, Rahj af gh&r,powder of the mine. Use. - Was used in fireworks to give a brilliant white light when mixed with saltpeter and ignited. The artificial material is now used for this purpose.

Jan 1, 1922

By William E. Ford, Edward Salisbury Dana

I. Sul~harsenites, Sulphantimonites, etc. In these sulpho-salts, as further explained on p. 320, sulphur takes the place of the oxygen in the commoner and better understood oxygen acids (as carbonic acid, H2COs, sulphuric acid, H4S04, phosphoric acid, H3P04, etc.). The species included are salts of the sulpho-acids of trivalent arsenic, antimony and bismuth. The most important acids are the ortho-acids,

Jan 1, 1922

By William L. Swager

This is the second in Mining Engineering's series of articles on sources, uses, production, and conservation of strategic minerals. "Cobalt" first in the series, appeared in February 1951.

Jan 5, 1951

By W. T. Lundy

THE forms in which sulphur is commonly found-native sulphur, sulphides of many metals and sulphates-are widely distributed throughout the world. The two first mentioned are the principal sources of sulphur. Substantial amounts of sulphur in some form are recovered from gases from industrial plants and from gases from smelters treating other minerals. In recent years, plants have been installed in the United States to recover sulphur in elemental form from sour gases."' The amount of sulphur so produced is small at the present time but undoubtedly will increase in the future. The recovery of sulphur from gases is not covered in this chapter, which is confined to: (1) native sulphur deposits of Texas and Louisiana; (2) those of Italy; (3) other scattered deposits of native sulphur; and (4) pyrites deposits found in many countries of the world.30 Sulphur, a nonmetallic element, occurs normally in well developed bipyramidal or tabular crystals of the orthorhombic system, as well as in stalactitic and earthy masses. The mineral has a distinctive yellow color, which may be dark and discolored by impurities; the streak is white; the luster is resinous; and the fracture is conchoidal to uneven. Sulphur is translucent to opaque; has a hardness of 1.5 to 2.5, a specific gravity of 2.05, and an atomic weight of 32.06.16 The molecular weight of the solid is expressed by the symbol SS and that of the liquid and vapor ranges from S2 to S8, depending on the temperature. Sulphur melts at a temperature between 2340 and 248°F, depending on its crystalline state, to a liquid of dark amber color, the boiling point of which is 832°F. The viscosity near the melting point is about that of water and increases to 50,000 times that of water at a temperature of 380°F, subsequently falling rapidly to a low figure at the boiling point. Crystallization changes slowly from rhombic to monoclinic above 205 °F and in cooling the transformation is reversed. The mineral is a very poor conductor of heat and electricity; it is insoluble in water and nearly all acids and is soluble in cold carbon bisulphide and carbon tetrachloride. It ignites in air at a temperature of 478°F, burning with a distinctive blue flame with evolution of sulphur dioxide.47

Jan 1, 1949

By Walter O. Snelling

IN combating mine-fires the use of carbon dioxide as a means of producing an atmosphere in which combustion cannot be sustained, has been many times suggested and frequently tried, generally with a fair degree of success. The carbon dioxide is produced by acting on limestone with dilute sulphuric acid, large wooden boxes being used to hold the limestone, and arranged in such a manner that one box may, be cleaned and refilled with blocks of limestone while another is being used in generating the carbon dioxide. The gas is led by means of pipes of large diameter to the location of the fire, tight brattices having been previously put up as close to the fire as possible on every side, so as to limit the space to be filled with the .gas to the smallest possible volume. The cost of producing Carbon Dioxide has been, however, a decided draw-back to the use of this method, and the danger of producing carbon monoxide by the reduction of the carbon dioxide by heated carbon, and consequently bringing about an explosion, has also tended to prevent the application of this method. The use of sulphur dioxide in combating mine-fires has not, I believe, been previously suggested or tried, and yet the method presents such decided advantages over the use of carbon dioxide that it seems proper to suggest the advisability of considering it as a cheap, convenient, and safe means of fighting stubborn mine-fires. 1. Cost, Preparation, etc.-One ton of brimstone, costing from $20 to $30, will produce about 25,000 cu. ft. of sulphur dioxide gas, and allowing for all sources of loss it is probable that sulphur dioxide gas can be produced for about $1,300 per 1,000,000 cu. ft. For carbon dioxide gas, produced by the action of sulphuric acid on limestone, a good estimate would be $4,000 per 1,000,000 cu. ft., provided that sulphuric acid

Sep 1, 1908

By Reed W. Hyde

SOME information has been published on the sulphur dioxide concentration of gases from Dwight-Lloyd machines sintering lead ores but most of this relates to the customary practice in which the charge is relatively high in lead and is sintered in two passes over the machine. It is thought, therefore, that the following observations on sintering in one pass a low-lead, low-sulphur charge may be of interest. The data were obtained in sintering lead sulphide flotation concentrates mixed with minus 20-mesh oxide ore, the mixture carrying 16.8 per cent Pb and 5.3 per cent S. No returns were used because of the limited amount of sulphur available as fuel, but the mixture pelletized readily to make a satisfactorily permeable bed on the sintering machine. As there was a possibility that the SO2 might be utilized, a series of runs was made to determine the concentration of SO2 in the gases at different points along the wind box, and the effect on this concentration of changes in the wind-box vacuum. Several runs each were made with vacuums (as measured in inches of water at the wind box) of (1) 2 to 1 3/4 in., (2) 4 to 3 1/2 in. and (3) 6 to 5 1/8 in. The averages of the determinations from each series are platted on the graph (Fig. I). The vertical scale shows the percentage by volume of SO2 (as determined by the Reich method), and the horizontal scale shows the time expressed as percentage of the total sintering time. Sintering was considered to be complete when no SO2 could be detected in the gases. In all cases the depth of bed was 4 1/2 in. and the weight of dry charge per square foot of hearth area was 45.2 lb. Other data are given in the table. The volume of gases corresponding to the several points along the wind box at which SO2 determinations were made could not be measured, but has been calculated from the SO2 content and sulphur elimination on the assumption that the volume is uniform throughout the sintering period. This is not strictly true, as with a given vacuum the volume will usually drop slightly toward the middle of the period and increase toward the end. However, this assumption is a reasonable approximation. Several interesting features are brought out by these data. In general, the published data on SO2 concentration in sintering under ordinary conditions show a high SO2 concentration in the early stages followed by a rapid decrease in concentration and with relatively little SO2 in the gases from the last half or third of the operation. In other words, the greater part of the sulphur elimination is obtained in the first third or half of the period. In these runs, the 6-in. vacuum, which approximates the usual operating condition, gives a curve that follows this customary pattern. Maximum SO2 concentration is obtained 2 ½ min. after

Jan 1, 1942

By Reed W. Hyde

SOME information has been published on the sulphur dioxide concentration of gases from Dwight-Lloyd machines sintering lead ores but most of this relates to the customary practice in which the charge is relatively high in lead and is sintered in two passes over the machine. It is thought, therefore, that the following observations on sintering in one pass a low-lead, low-sulphur charge may be of interest. The data were obtained in sintering lead sulphide flotation concentrates mixed with minus 20-mesh oxide ore, the mixture carrying 16.8 per cent Pb and 5.3 per cent S. No returns were used because of the limited amount of sulphur available as fuel, but the mixture pelletized readily to make a satisfactorily permeable bed on the sintering machine. As there was a possibility that the SO2 might be utilized, a series of runs was made to determine the concentration of S02 in the gases at different points along the wind box, and the effect on this concentration of changes in the wind-box vacuum. Several runs each were made with vacuums (as measured in inches of water at the wind box) of (1) 2 to 1 1/3 in., (2) 4 to 3 1/2 in. and (3) 6 to 5 1/8 in. The averages of the determinations from each series are platted on the graph (Fig. I). The vertical scale shows the percentage by volume of SO2 (as determined by the Reich method), and the horizontal scale shows the time expressed as percentage of the total sintering time. Sintering was considered to be complete when no S02 could be detected in the gases. In all cases the depth of bed was 4 ½ in. and the weight of dry charge per square foot of hearth area was 45.2 lb. Other data are given in the table. The volume of gases corresponding to the several points along the wind box at which S02 determinations were made could not be measured, but has been calculated from the S02 content and sulphur elimination on the assumption that the volume is uniform throughout the sintering period. This is not strictly true, as with a given vacuum the volume will usually drop slightly toward the middle of the period and increase toward the end. However, this assumption is a reasonable approximation. Several interesting features are brought out by these data. In general, the published data on S02 concentration in sintering under ordinary conditions show a high S02 concentration in the early stages followed by a rapid decrease in concentration and with relatively little SO2 in the gases from the last half or third of the operation. In other words, the greater part of the sulphur elimination is obtained in the first third or half of the period. In these runs, the 6-in. vacuum, which approximates the usual operating condition, gives a curve that follows this customary pattern. Maximum S02 concentration is obtained 2 ½ min. after

Jan 1, 1942

By Nicholas J. Grant, John Chipman

A FULL understanding of the behavior of sulphur in the basic open-hearth process has been delayed by lack of dependable data covering a wide range of slag conditions in the absence of other complicating factors that are likely to be present under operating conditions. It has been generally accepted that strongly basic slags will dissolve more sulphur than will those in which the acidic and basic constituents are more nearly balanced. It has been known that both slag and metal would absorb sulphur from the flame when the sulphur content of the fuel is high. It has been generally believed that manganese assists in the transfer of sulphur from metal to slag. Almost nothing has been known of the effect of temperature upon desulphurization; the data have been conflicting and there has been a tendency to depend rather heavily upon analogy with the better understood desulphurizing reaction of the blast furnace. Many attempts have been made to build up from open-hearth data a satisfactory theory of the chemical reactions involved in the process. That this has been an extremely difficult task is owing to two reasons that have been very generally recognized. The first is the parallel and simultaneous reaction of sulphur transfer between flame and bath. The second is the difficulty of distinguishing between the factors that ultimately limit the transfer from metal to slag-i.e., equilibrium conditions-and those whose influence is only upon the rate of transfer. It has been the object of the work here recounted to study the equilibrium distribution of sulphur between slag and metal in the absence of these complicating factors, with the hope that a better understanding of the equilibria involved would lead to a better control of the over-all process in the open-hearth furnace. A review of the literature on steelmaking reveals almost complete agreement with respect to the paramount importance of lime in promoting desulphurization. In expressing this effect in quantitative terms, however, and in formulating the relationships between the concentrations of other slag components and the desulphurizing power, there is little agreement. For instance, the "basicity" or basic strength of the slag is commonly measured by some kind of ratio of concentration of basic to acidic oxides. Of these, the following have been reviewed by Schenck :20 [ ] Among others there appear the following:

Jan 1, 1946

By F. Louis Grammer

THE difference between blast-furnace gas and ordinary producer-gas is chiefly that blast-furnace gas is richer in CO, and poorer in hydrocarbons and hydrogen, as is shown in Table I. TABLE I.-Volume-Composition of Producer-Gas and Blast-Furnace Gas.. Producer-Gas. Blast-Furnace Gas. Per Cent. Per Cent. (Volume.) (Volume.) CO . 22 to 33 25.5 00., . 6 to 3 13.0 H . . 13 to 7 1.5 CH, 3 to 1.5 0.0 N . 54 to 60 60.0 If natural gas, water-gas, or by-product coke-oven gas be available, blast-furnace gas can be made to resemble very closely in calorific value the average producer-gas by merely mixing in one of these products, which are richer in hydro-carbons and, hydrogen. Blast-furnace gas, however, possesses a virtue which is sometimes absent in producer-gas, especially with coals very high in sulphur-namely, that blast-furnace gas is relatively free from sulphur. In some regions the sulphur in coal is an acute problem, and it is highly desirable to find uses for the products which are specially high in sulphur-content. An advantage would be gained if coal was coked before charging into the gas-producers, but this adds to the expense. Sulphur may be partly eliminated from coal by washing it, the success depending upon the form in which the sulphur occurs, and upon the efficiency of the washer, but it cannot always be removed to the extent desired at most American plants. It is not practicable to remove all the sulphur from producer-gas by washing it, though Mr. Reinhardt, of Germany,

Sep 1, 1908

By Thomas P. Forbath

THE sudden realization that known sulphur reserves amenable to mining by the Frasch hot water process are nearing exhaustion focused attention on widely scattered surface deposits throughout the world. These deposits are not necessarily of lower sulphur content than ores located underneath Louisiana or Texas salt domes which usually aver- age about 30 pct sulphur disseminated in limestone matrix. Their near surface occurrence, however, renders exploitation by the Frasch process impossible. As is well known, the Frasch process depends on the presence of 500 to 1000 ft of overburden and cap rock above the sulphur deposits to permit melting underground sulphur in place by diffusing hot water under pressures of 200 to 600 psig in the formation and raising the molten sulphur to surface by air lift. This process renders possible the production of pure sulphur which is 99.5 pct pure without any subsequent treatment.

Jan 9, 1953

By M. Lastra, A. Cruz, J. Menacho

The technical feasibility of treating exotic copper ore with an acid cure using concentrated H2S04 is studied. Applications in a conventional percolation leaching circuit for unaltered ore and in a conventional agitation leaching circuit for altered ore are examined. The main effects of an acid cure are to inhibit silica dissolution and to increase the sedimentation rate of agitated pulps. An increase in the rate and degree of copper extraction is also observed. Based on these results and the minimal additional investment required, acid curing appears to provide an excellent approach for treating exotic copper ores.

Jan 1, 1980

DESIRABLE as it is to summarize what has been set forth in preceding chapters, the task can only be approached with great hesitation. What follows represents the personal views of the author at the moment of writing, reserving the privilege to change them on more mature reflection or in the light of further evidence. With that reservation they may be stated somewhat as follows. Education for the mineral industries falls into two categories; general education and technical vocational, using the word vocational not in its usual sense but to signify preparation for specific activities, in which sense a law school is a vocational school. Even at the beginning, as indicated in the first chapter, mineral industry education was partly general and partly technical and that relationship still persists, because technical education requires a firm basis of general education. Our general American system is to provide free public general education through the twelfth grade, or completion of high-school work, though there are already many technical vocational high schools, and even in a community where nearly all the young people are preparing for entrance to college there will be some who wish to qualify for employment at the end of the high-school course, or even on completing junior high. Our educational system, therefore, has not only to provide education for those who intend to proceed beyond the twelfth grade but also for those who, for a variety of reasons, may wish or be forced to cease full-time education at any level between the first and twelfth grades. This study has been chiefly concerned with the problem of what kind and how much technical education to provide for those who have completed the twelfth grade and who wish to make their living in the mineral industries. The obvious fact that the mineral industries employ all sorts of trained persons,

Jan 1, 1941

From the historical account of the coal industry set forth in the preceding pages the reader will have learned that coal is extremely widely spread throughout the United States, and in most places it has been easily found, that it has been remarkably easy to develop, and, where the deposits were available to streams on which it could be transported to markets, it was opened almost as soon as the country was settled. Such were the mines along the James, Susquehanna, Monongahela, Ohio, Kentucky, Cumberland and Big Muddy Rivers. In other localities where such easy means of transport were not convenient, the early production was confined to local use, or to places to which it could be hauled by wagons, but everywhere small mines were established almost as soon as the country was settled, and these increased both in number and size as the available markets grew. These early mines were nearly always opened by local people, and the industry was so far-flung that its growth attracted little or no attention excepting when a labor disturbance or a breakdown in transportation occurred. Had it been concentrated in a few places as most metal industries were, or as the petroleum industry was for many years after it started, it is probable that much better records of its progress would have been kept. When the canal era began, in the eighteen twenties, coal was at first not considered as a valuable source of freight revenue, and much surprise was expressed that the receipts of the Schuylkill Canal were very largely from coal after the first few years, as was the case of the Union Canal though not to such an extent. Even the early railroads to the coal fields did not realize the extent to which the products of mines would figure in their revenues, and it was many years before railroads were built practically solely for prospective coal traffic; indeed this did not happen until some years after the Civil War. Map 12 shows the extent of the canal system in the United States in its relation to the coal fields at the time of its maximum development. It will be seen that only the coal areas in Pennsylvania, Ohio, and to a very small extent in Indiana were able to ship by canal at all, and that only a very small portion of such fields could do so. Looking backward, it is hard to understand the great hopes entertained of canals by their pro-

Jan 1, 1942

By Thomas T., Read

DESIRABLE as it is to summarize what has been set forth in preceding chapters, the task can only be approached with great hesitation. What follows represents the personal views of the author at the moment of writing, reserving the privilege to change them on more mature reflection or in the light of further evidence. With that reservation they may be stated somewhat as follows. Education for the mineral industries falls into two categories; general education and technical vocational, using the word vocational not in its usual sense but to signify preparation for specific activities, in which sense a law school is a vocational school. Even at the beginning, as indicated in the first chapter, mineral industry education was partly general and, partly technical and that relationship still persists, because technical education requires a firm basis of general education. Our general American system is to provide free public' general education through the twelfth grade, or completion of high-school work, though there are already many technical vocational high schools, and even in a community where nearly all the young people are preparing for entrance to college there will be some who wish to qualify for employment at the end of the high-school course, or even on completing junior high. Our educational system, therefore, has not only to provide education for those who intend to proceed beyond the twelfth grade but also for those who, for a variety of reasons, may wish or be forced to cease full-time education at any level between the first and twelfth grades. This study has been chiefly concerned with the problem of what kind and how much technical education to provide for those who have completed the twelfth grade and who wish to make their living in the mineral industries. The obvious fact that the mineral industries employ all sorts of trained persons,

Jan 1, 1941

IN THE past, we have, perhaps, been somewhat careless in our furnace practice, in the use of high-grade material, lowering the production costs through demanding high-grade ores, increasing the size of units, and eliminating heat losses by collecting and returning unused heat to our furnaces. Further economies would seem to be possible through keeping out of the furnace those materials that appear to serve no useful purpose and carry with them heat that should be used in reduction operations. In the manufacture of pig iron, about three tons of inert nitrogen pass through the furnace for each ton of iron produced. This nitrogen serves no useful purpose in the chemical actions involved, but when discharged into the atmosphere it carries away a considerable quantity of heat. Can not this loss be eliminated, at least in part, through the use of more oxygen in the blast? Many metallurgical chemists, during the past 20 years, have stated that they thought it can and have urged that the plan be tried. Others have expressed doubt, not being able to visualize how more oxygen could be used in present practice; they have regarded it as impracticable, without trying to conceive of an entirely new practice based on a new reagent. That more experimental work has not been done is due to the fact that no cheap oxygen has been available, but the committee believes that there is strong reason to expect that, should a demand exist, 99 per cent. oxygen may be made at a cost not to exceed $3 per ton. The theoretical studies of the committee have indicated such marked economy by using oxygenated air in various operations that its members strongly recommend experimental work to verify the anticipated economies. The committee has developed plans for experimentally determining the effects of oxygen-enriched air on the operation of an iron, blast furnace. A furnace with a height of 30 ft. has been built and it is recommended that the plans be put in, effect as the first step in the research.

Jan 11, 1924