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By E. V. Manlapig

"Some researchers postulate that the floatability of a particle in the streams of an industrial flotation circuit is a function of only its size and liberation properties. They do not discount the importance of reagent or surface contamination on particle floatability but assume that the reagent coverage or surface contamination of the particle surfaces is essentially uniform for particles of similar size and mineralogical properties when subjected to a particular chemical regime.In this paper, samples collected from laboratory batch flotation tests performed on different streams of Cominco Teck’s Red Dog lead cleaning circuit have been characterised with respect to their size, mineral association and mineral surface exposure. An analysis of this data set indicates that the flotation rate of a particle in an industrial flotation environment is a strong function of its size and also of the mineral composition of its surface (Figure 1). It is a function not only of the proportion of the most floatable mineral on its surface but of the floatability of the other minerals on its surface as well.Nodal analysis is a technique developed by the authors that can be used to determine if the ore floatability of a particle class is changing within an industrial flotation circuit. This technique is used within the paper to show that the floatability of all the different types of particle classes studied within the Red Dog circuit did not change significantly during the lead cleaning stage. However, it was also concluded that particles with the same size and mineral composition did not all float with the same rate in the individual streams of the flotation circuit, but with a distribution of rates. It is suspected that the particles within a size mineralogical class in this study have varying degrees of surface oxidation and that this results in varying particle flotation rates. Thus basing particle floatability on size and mineralogical effects, alone, in a flotation model is not always valid."

Jan 1, 2003

By Harry Tufft

FOR many years the treatment of mine timbers with preservatives was confined to a few pioneer plants in the United States, and it is only in the past few years that the practice has grown appreciably. In a field study of the mine timber situation in Illinois, Pennsylvania, and further study of the situation in the country as a whole, I found that most mine operators did not keep records on mine timber that would afford the necessary data for determining the possible savings from preservative treatment. Some primary questions the mining engineer should be able to answer before making his decision on preservative treatment. for a particular mine are: (1) Quantity and cost of timber going into permanent workings annually; (2) quantity and cost of annual replacements due to decay; (3) life of untreated timber in different places; (4) desired life of timber. With the necessary facts in hand, he can then con-fidently select a method of treatment and preservative that is best suited to his needs. In former years when timber was cheap and an abundant supply could be had close at hand, as was the case in the majority of mining regions, the mine op-erator did not concern himself much except to see that enough was supplied to keep the workings safe. The cost figure for timber and labor, distributed to cost per ton of ore, was all the bookkeeping necessary. With present costs of timber, labor, and increasing length of haul to the mine, many operators are paying closer attention to timbering costs and studying them in. more detail. Some of the larger and more progressive opera-tions now keep detailed' figures that give information on all phases of their timber problems. However, at the majority of mines the data available do not permit such analysis. Checks as to where the different con-signments are placed, the date of setting, and the period

Jan 6, 1927

By P. D. Wilson

The genesis of some orebodies has been explained by the mingling and chemical interaction of water solutions of different compositions and the consequent precipitation of the mineral load of one or both solutions at their confluence. While this process can be proved in the laboratory, rarely can a positive demonstration be found in nature, for the conditions at the time an ore deposit is being worked are usually entircly differcnt from those that existed when the orebody was formed. For this reason, the present deposition of copper carbonate in the southern end of the Briggs mine of the Calumet and Arizona Mining Co. near Bisbce, Ariz., is of great interest. The developed orebodies in the Calumet and Arizona mines are roughly confined to two broad parallel zones separated at the north by a wedge of Copper Queen ground and at the south by an undeveloped block of Calumet and Arizona ground about 2000 ft. (610 m.) wide. The more westerly zone includes the Irish Mag, Oliver, P. and D., and Cole mines, none of which has been operated since 1919. Much of the water from this division is carried from the 1400-ft., or bottom, level at the southern end of the Cole mine in a long water drift through the undeveloped block to the 1300-ft. level of the Briggs mine at the southern end of the more easterly zone. Most of this water comes originally from outlying areas in the P. and D. mine, passing through parts of the lower. levels of the Cole mine, which are heavily mineralized with iron and copper sulfides. This sulfide zone has been opened up and slowly oxidizing for years. Originally a pure, potable water, the analyses of which are shown under A- in Tables 1 and 2, on its way through the mineralized area in the Cole mine it gathers copper, calcium, magnesium, iron, and aluminum sulfates, a load of dissolved mineral salts almost four times as great as that which it formerly carried; analyses B

Jan 1, 1923

By Enrique Touceda, Henry M. Howe

This paper gives the composition of the iron and slag at different stages in the " air-furnace" process of preparing " hard metal," or white castriron, for conversion into malleable cast-iron by annealing. The details of the process are given in an appendix. One of us had been trying for years to work some chemist of some of our malleable-iron plants up to a degree of enthusiasm which would lead him to make such an investigation. It would have had the advantage of the greater familiarity with the conditions which one habitually on the spot must have. Failing in this, he made use of an opportunity which presented itself of taking samples here represented, with such fairness as the conditions permitted, holding firmly that a rough approximation to the truth is better than the complete lack of data, or that a bird in the hand is worth two in the bush. We hope that this attempt may stimulate others effectively to duplicate this work, and thus correct or confirm it. Our results are shown in Table I. and graphically in Figs. 1 arid 2. Discussion.—At the time when the first two samples were taken, the metal and slag were still too sluggish to permit fair sampling, and not until sample 6 were the conditions really favorable, because at the time of the fourth sample the metal was not fully melted, and even at the time of sample 5 it was still sluggish. Indeed, the slag was probably very heterogeneous throughout, because it took up silica and alumina rapidly from the bottom, and because it was so siliceous as to be sluggish at this relatively low temperature. This hetero-geneousness is exaggerated in the two samples of slag 8, apparently by the great viscosity due to its extraordinary acidity. Note that the manganous oxide of one sample is about two and

Jan 1, 1909

By T Hausler

The pitfalls, pleasures and management issues associated with international and remote projects are diverse.However, no problem is insurmountable and if an engineering team chooses (by luck or good planning) to push through the difficulties, success can mean an extremely satisfying experience for individuals and a significant, positive result for an organisation.International projects are not for the faint hearted or inflexible. Working in foreign lands with people who may or may not speak English and who may not initially respect you can become mentally and physically tiring.Sometimes the challenges are not fully explained to individuals in advance. Individuals then often learn about the challenges ù and discover solutions ù on the job. While this initially puts great pressure on individuals, matters improve eventually, especially when the locals come to understand that you are on site to make a positive difference.This paper will discuss aspects of a recent international project including meeting international clientsÆ expectations, dealing with cultural differences, social reckoning, environmental issues, and personal challenges. Specifically, it will cover aspects of working within a Russian cultural setting and overcoming social barriers.The paper also presents coping strategies for long periods of time spent away from home in remote places with extremes in weather beyond the normal experience of most Australians. For example, dealing with the effects of the spring thaw and coping with temperature ranges of -45 to +45¦C.Lastly, and possibly most importantly, there will be a focus on the role of translators. They have the power to make an engineer everyoneÆs best friend or, on your behalf, to order cold chicken liver and heart salad for lunch. If an engineering team can establish a working relationship with translators, they can become an invaluable asset and both on and off site.CITATION:Hausler, T, 2013. Achieving success in large-scale, remote area metallurgical plant projects, in Proceedings MetPlant 2013 , pp 539-552 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 15, 2013

On August 4, 1844, J. C. Fremont made the first record found of coal in Wyoming. On the North Fork of the Platte River, beyond Medicine Butte, in Carbon County, he noted: "in the precipitous bluffs were displayed a succession of strata containing fossil, vegetable remains, and several beds of coal. In some of the beds, the coal did not appear to be perfectly mineralized; and in some of the seams, it was compact and remarkably lustrous." A little later he noted, "longitude 111°, latitude 4 1/2°-Muddy R.--coal."1 In 1848, Clayton reported coal on Sulphur Creek near the site of old Bear River City, in Uinta County.2 Maj. Osborne Cross in his journal, on July 1, 1849, records seeing coal on Deer Creek and in one of the hills near Crooked Muddy Creek, in Converse County; on July 7, he records that the country from Deer Creek to the Sweetwater River abounds in coal, probably in Natrona and Carbon Counties.3 A letter from Asst. Quartermaster Van Vliet to General Jessup dated July 25, 1850, asked an appropriation for building shops at Fort Laramie for making repairs for the emigrants, and mentions "coal and timber," but undoubtedly meant charcoal, as no other mention of stone coal is made in the records of the fort.4 Stansbury, in 1852, placed on his map of this section the words: "Great Coal Basin," extending from the west bank of Bear River, near the present Evanston, to Point of Rocks in Sweetwater County. In 1859, a military coal reservation was established near here, but the coal was never worked to any great extent, although probably some was hauled to Fort Bridger for smithing purposes. When the fort was abandoned this reservation returned to the public lands .2 In the same year (1859), Hayden traced the lignite formation uninterruptedly from the upper Missouri Valley to a point on the North Platte River, about 80 miles northwest of Fort Laramie.5 On August 25, 1865,

Jan 1, 1942

By R. C. Kirkman

Your interesting and well-written paper brings up the issue of the purpose or use of a mineral property appraisal, specifically the value of these evaluations when the quality and quantity of the mineral resource to be exploited have not been thoroughly investigated. I am not a practicing professional in regards to valuation of limestone investment opportunities. I simply wish to make a few generic observations about the appraisal process in order to stimulate meaningful thinking by appraisal professionals whose reports may be reviewed by professional investors and "laypersons" alike. It is my contention that the analysis given in your paper is very thorough, considering the data that was made available to you. But I would not like to be the person responsible for investment decision making without having a feel for the risk involved. Therefore, the reviewer must classify this type of analysis as relatively "subjective" because they have not received an indication of the inherent risk involved in exploiting a mineral resource. This risk can best be quantified by using probabilistic methods in conjunction with the quality and quantity of the mineral to be produced. Most appraisals passively ignore this problem. Specifically, you have accurately identified the various costs and values entering the economic appraisal process. These can usually be quantified with a great deal more certainty than the capability of the resource to provide 25 years of quality material. Also, in Cases A (West Virginia)and B (Alabama), you are fortunate enough to have previous operations data. What if there had never been production from these properties? How does a potential mineral property investor evaluate the resource capability to meet various projected financial outcomes without spending a good deal of up-front capital to drill and delineate enough quality resources for a 20-plus year operation. These questions pose a substantial risk to any potential mineral investor. Only probabilistic methods should be used to quantify this type of problem, short of drilling and metallurgical testing. I might be considered a "layperson," not being familiar

Jan 1, 1991

R. F. WOOD,* Sandusky, Ohio.-I made a few tests of gun-metal specimens, after I noticed the results on quenching -reported by the Bureau of Standards. The data of one such test are given herewith. The bars were heat treated and quenched before they were machined, and in all cases they were brought up to 700° or 800°. They became extremely brittle,, showed almost no elongation, except such as was caused by the failure of the pieces to fit together after they were pulled, and the tensile stength was reduced from around 35,000 to about 13,000 lb. per sq. in. In addition, the weakening effect of the quenching seemed to be almost as marked when the bar was allowed to slowly air-cool from red to black, and then quenched, as it was by quenching directly from the red heat. Test Bars.-Rough size, 9/16 in. diam. over test section, grips 13/16 in. diam. Cast two in a flask, one on each side of a block 8 by 4 by 1 in. and fin-gated thereto from the grips but not from the test section. Poured with flask in inclined position, with gate to lower end of block and riser from upper end of each test bar. Bars were machined to ½ in. over the test section, after heat treatment. Casting the Bars.-Charge of 1500 lb. consisting of 400 lb. of new metals and 1100 lb. of G turnings and scrap was melted in open-flame oil furnaces and then poured into a 1-ton ladle. From the ladle 150 lb. was poured into a preheated No. 50 crucible, land from this the flasks of test bars were poured. The six flasks are indicated below by the numbers 1 to 6 and the bars in each flask by the letters a and b, thus 4a and 4h, for instance, were the two bars in flask No. 4.

Jan 12, 1919

By T. B. Counselman

"C" VERYONE who has to calculate cyanide circuits, -¦-' using either thickeners, filters or both, realizes the headaches involved in solving a set of simultaneous equations. When you calculate a large number of these, based on experimental data, trying to arrive at the best flowsheet, you can spend days at the task. T. B. COUNSELMAN, Member AIME, is Manager, FluoSolids Division, The Dorr CO., Stamford, Conn. AIME New York Meeting, Feb. 1950. TP 2783 B. Discussion (2 copies) may be sent to Transactions AIME before March 31, 1950. Manuscript received Aug. 23, 1949. Herewith is presented a short method, equally accurate with the standard simultaneous equation method, and much quicker. Here for instance is the standard simultaneous equation method, for 100 tons per day of $10 ore, with the conditions assumed as below (fig. 1). Conditions Assumed a. 100 tons of ore per day crushed in cyanide solution. b. Discharge from all thickeners with 50 pct moisture. c. $10 value dissolved per ton of ore. d. 50 pct in mill and 50 pct in agitators. e. 400 tons of solution from thickener V precipitated to $0.02. f. Agitation with a dilution of 2 of solution to 1 of solids. g. Let V, W, X, Y and Z represent value in dollars per ton of solution discharged from the resvective thickeners. Equating Out of and Into Each Thickener 1. lOOVplus 400V = 500W plus (0.50 X $10 X 100) 2. 1OOWplus 600W= 500X plus lOOW plus (0.50 X $10 X 100) plus lOOV 3. lOOXplus 500X = 1OOWplus 500Y 4. 1OOY plus 500Y = 1002 plus 1OOX plus (400 X 0.02) 5. 100 Zplus l00Z = l00Y plus 100 tons of water (value $0.00) Simplifying: 1. v = W plus 1.00 2. W = X plus 1.20 3. X = Y plus 0.24 4. Y = 0.2Zvlus 0.064 5. 2Z= Y

Jan 1, 1951

By C. G. Dunn, M. Sharp

HE orientations of 137 crystals of copper pro-T duced by secondary recrystallization in a cube texture matrix have recently been obtained. Although the crystals were not prepared for the purpose of determining a secondary recrystallization texture, the orientations obtained proved to be rather interesting, as they confirmed, in part, published results and also disclosed additional preferred orientations in the texture. The investigation of Dahl and Pawlek,&apos; Bowles and Boas,&apos; and Kronberg and Wilson3 showed respectively that the orientations of secondary grains growing in a cube texture matrix were related to those of the primary grains by a rotation of approximately 30" about [001], the rolling direction, by 30" about a <111> direction, and by either 22" or 38" about a <111> direction. Kronberg and Wilson also obtained a component of the texture similar to that of Dahl and Pawlek except the angle of rotation about [001] was 19". When the cube texture matrix was deformed a small amount, Kronberg and Wilson also obtained large grains on subsequent annealing corresponding to a rotation of 15" about the normal to the sheet, but these grains should not be classified as secondary recrystallization grains since they were produced subsequent to mechanical straining. The particular texture obtained, of course, depends on the composition of the copper and the processing schedule employed, since these factors markedly affect the primary recrystallization texture and the sharpness of any cube texture produced. In the present investigation, pieces of OFHC copper in the form of M in. round bars were cold forged to a thickness of about 0.40 in., annealed 1 hr at 350°C in an atmosphere of hydrogen, and cold rolled crosswise to a thickness of 0.200 in. These pieces were given a penultimate anneal of 1 hr at 350°C in hydrogen and a 90 pct cold-rolling reduction lengthwise to a thickness of 0.020 in. Indentations generally were put in one end of the as-cold-rolled strips to promote earlier formation of secondary grains.

Jan 1, 1953

By Lon Santis, Scott Deitchman, John A. Decker

This report describes three cases of carbon monoxide (CO) poisoning in a manhole, including one fatality, from CO migrating through soil after nearby use of explosives. A municipal sewer project involved installation of new pipes and manholes. Work of the general construction contractor was interrupted when a subcontractor detonated 265 pounds of nitroglycerin-based explosive 40-60 feet south of the manhole to break up underlying rock. A construction worker who descended into the manhole 45 minutes after the explosion collapsed within minutes, and two co-workers descended into the manhole to rescue him. One rescuer retrieved the unconscious worker, and the other rescuer died in the manhole. All workers had elevated carboxyhemoglobin levels. In the subsequent NIOSH investigation, air monitoring was conducted with real-time instruments, and air samples were collected in Tedlar bags. Laboratory analyses of the bag samples collected near the bottom showed 1905 parts per million (ppm) CO, 19.5% oxygen, and 3% carbon dioxide. Direct reading instruments showed progressively higher concentrations as the sensor was lowered into the manhole. Subsequent chamber tests on sample explosive yielded 27 liters CO per kilogram detonated. Based on this value, the surface blast at the construction site may have produced about 3,250 liters (114.8 cubic feet) CO. The CO in this incident most likely was released from the nearby explosion and migrated through soil and fractured rock into the manhole. The blasting and construction industries should be made aware of this previously unrecognized CO exposure hazard associated with surface blasting. The extent of CO exposure from explosives used in construction is not known, and additional information on the extent of CO exposure must be collected. In addition, confined space entry procedures (including monitoring confined space atmospheres before entry) should be observed; CO monitoring of confined spaces in the presence of blasting can prevent future incidents such as this one.

Oct 30, 1997

By A. M. Stone

INTRODUCTION In ore beneficiation one of the simplest methods of mineral concentration is hand picking to remove either the ore or the waste material from a moving table or conveyor belt. Ore Sorting Equipment may be defined as equipment for mechanized picking. This type of equipment has been used successfully over the past thirty years or so to beneficiate ores of various types in particle mesh sizes between 1mm and 200mm.. at throughputs of up to 150 tonnes per hour. In general for ore sorting to be a consideration the ore and the waste material must be well liberated in the feed to the sorter (that is into practically discrete particles of ore and waste). The larger the liberation size the more likely sorting is to be cost effective. Correct selection of ore sorting equipment is most important and often special machine features are developed for an individual application. Sorter performance can be best determined by extensive testwork of representative ore at design tonnage on prototype or preferably on production model sorting machines. ADVANTAGES OF SORTING ORE The four main advantages of sorting ore are: Reduced milling cost. Reduced processing cost. Higher overall recovery. Reduced transportation costs. Reduced Milling Cost With sorters installed the milling plant following the sorter is generally smaller and hence less costly to install and operate as it only has to handle the sorter product. However this benefit is somewhat offset by the increased cost of the screening and washing plant prior to the sorter and the cost of the sorting plant itself. Reduced Processing Cost As there is less material of higher grade presented to the concentrating plant following the sorter, this plant will generally be smaller and less costly to construct and operate than a plant treating the total quantity of material. Higher Overall Recovery The economic recovery is often misunderstood by plant operators when evaluating the advantages of sorters

Jan 1, 1986

By T. A. Rickard

Clement Le Neve Foster was born at Camberwell on March 23, 1841, his father being Peter Le Neve Foster, who was secretary of the Society of Arts for 26 years. As a boy of 12 he was sent to school at Boulogne, receiving a preliminary education there; and in 1857, when only 16 years old, he took his degree of Bachelor of Science from the University of France. In October of the same year he returned to London and entered the Royal School of Mines, which was then in Jermyn Street. He distinguished himself by winning a scholarship and a medal, and by securing his degree as Associate of the Royal School of Mines in the abbreviated period of two years. This was followed by a year at the Bergakademie at Freiberg; subseque1:tly he visited several mining districts in Germany and Hungary. On returning to England, in November, 1860, he received from Sir Roderick Murchison an appointment upon the Geological Survey. During five years he was engaged in field-work, first on the Wealden beds in Kent and Sussex, and then in Derbyshire and Yorkshire. At this time his evenings were largely devoted to reading for a degree from London University. In 1861 he matriculated, obtaining the Bachelor of Science in 1863, with honors in biology and a University scholarship in geology; in 1864 he passed the two examinations entitling him to the Bachelor of Arts degree, and in 1865 he received the degree of Doctor of Science. In 1865 he succeeded Mr. Richard Pearce as lecturer to the Miners&apos; Association of Cornwall and Devon. At the same time he became the curator to the museum of the Royal Geological Society of Cornwall at Penzance, a member of the council in 1873, and a life-member in 1874; he made frequent donations to the museum, besides contributing several valuable papers to

Jan 1, 1905

By J. H. Bechtold

Tensile properties of annealed molybdenum were investigated from 1000" to—200°C. In the vicinity of room temperature a well-defined transition in tensile properties occurs. Reduction in area decreases from over 80 pct to 0 pct and, simultaneously, the yield strength increases about 60,000 psi. MOLYBDENUM, tungsten, iron, and many other metals and alloys with the body-centered cubic and hexagonal close-packed crystal structures change from ductile to brittle behavior over some relatively narrow temperature range. The temperature at which this transition in ductility occurs depends on chemical composition, microstructure, and method of testing. When fine grained, completely recrystallized molybdenum of commercial purity is tested in uniaxial tension at a slow strain rate, the transition occurs at slightly below room temperature.&apos; Iron2 and tungsten3 tested under similar conditions become brittle at temperatures close to the boiling point of nitrogen, — 195°C and at about 200°C, respectively. A sharp change in ductility is uncommon in metals with the face-centered cubic crystal structure, however, a relatively sharp transi- tion in notched bar impact properties has been observed below room temperature in a face-centered cubic copper-antimony alloy.4 A transition from ductile to brittle behavior is usually explained by the concepts originally developed by Ludwik,5 and discussed and elaborated on by others including Orowan,6 Hollomon and Jaffe,7 and Gensamer8 In brief, there are two aspects to strength, first the resistance to flow and second the resistance to fracture. Both are functions of temperature, strain, strain rate, stress system, composition, and microstructure. With decreased test temperature the flow stress required to initiate plastic deformation increases more rapidly than the fracture strength and brittle fracture occurs at that temperature where the yield strength equals or exceeds a brittle fracture strength. This investigation was conducted to determine the effects of temperature, strain, and rate of straining on the flow and fracture strengths of molybdenum above, through, and below the ductile-to-brittle transition. Other variables were held constant during testing. This information is believed to show

Jan 1, 1954

By C. E. Arnold

IN attacking the problems of mining and treating large disseminated copper orebodies such as those occurring in the Miami or the Ray district of Arizona, one of the vital questions to be decided is, "What is the value of the orebody per ton in place?", The importance of this question lies in the fact that its answer helps to reach a decision concerning the method of mining to be employed. Let it be assumed for the moment that milling and smelting practice, especially the latter, is more or less standardized; and has a cost incapable of much variation, while the cost of mining has a considerable range owing to the large number of mining methods by which a mine may be exploited. For instance, a method may be adopted whereby all the available ore can be extracted perfectly clean (i.e., unmixed with barren material) at a relatively high cost; or a method may be used involving the necessary dilution of a portion of the ore with waste, in order to recover that portion, thus giving a relatively poorer extraction but nevertheless a lower working cost than the former method. Naturally, between these two extremes there lie intermediate methods. In order to arrive at a solution of a mining method problem that is of any value, it is necessary that accurate and complete estimates of mining, milling, and smelting performances and costs shall be established. By way of illustration is given a, case of mining, by the system of undercutting and caving, a large orebody with an average content of 1.50 per cent. copper supposedly all in sulphide form, to which case has been applied those results in mining operations which one may fairly assume are to be expected when viewed in the light of G. R. Lehman&apos;s ore-drawing experiments, which form the subject of a paper to be presented at this meeting. It is assumed that the total. costs will be as shown in the following table:

Jan 9, 1916

By Heinrich Ries

The fusion-point of clay has usually been considered to be influenced chiefly by the quantity of fluxing impurities which the clay contained. Those clays which contain a high percentage of fluxes, such as ferric oxide, lirne, magnesia, and alkalies, fuse at a low temperature. Aside from the percentage of fluxing-impurities, the size of the grains exerts an important influence. Yet, while this fact has, no doubt, been recognized by many, practically no attempts have been made to prove it by actual experiment, although in the case of fire-clays, Prof. H. O. Hofman has rather disputed it. To illustrate the point more clearly, suppose a clay to be made up of a mixture of very refractory grains, such as kaolinite, and some fusible ones. If this clay be heated, the more easily fusible grains will melt first on the surface, and the softening under heat will gradually extend from the surface of the grain to its center. The larger, therefore, the size of the grain, the longer the time required for the heat to penetrate it. Now, if two samples of clay contain the same volume of flux, but of unequal size, the one containing the smaller-sized grains should fuse first, because the fluxing materials are more evenly and thoroughly distributed through the clay, so that they will more or less surround the refractory grains, which tend to act as a framework and hold up the clay-mass when heated. In order to demonstrate the effect of fineness of grain on the fusibility of clay, several mixtures were made up, consisting of white clay and other minerals. The white clay used was a very refractory type from Georgia, the fusion-point of which lay about cone 35 of the Seger series. The mixtures were formed into small bars 1* inches long, and set on a narrow surface, so that the ends were free to bend as soon as the mass softened. They were burned in a Seger gas-furnace.

Jan 1, 1904

By Franklin R. Carpenter, W. P. Headden

TWO notes have already appeared in the Transactions concerning the columbite or tantalite of the Black Hills tin-mines. In vol. xiii., page 232, Prof. Schaeffer speaks of the mineral as tantalite, and concludes by saying that its separation from the tinstone "is a matter which will, I believe, prove puzzling to the wisest metallurgist." He also observes that he is unable to find by analysis in his specimens the least trace of columbic acid. Prof. W. P. Blake, in the same volume, at page 696, says: " Even if it [tantalite or columbite] were present to a considerable amount, it would not injure the tin in smelting. It does not alloy with tin, but carries a small percentage of tin, which would probably be liberated in smelting." He calls the mineral columbite from the fact that a great number of specificgravity tests invariably indicated that it should be so classed. We have made chemical tests as well as specific-gravity tests upon many samples from many different parts of the Hills. Our analyses have always shown the presence of columbic acid, and the specificgravity tests have always indicated columbite, as we have elsewhere shown.* As Prof. Blake has already observed, it is not found in such close association with the tin as to prevent separation by a rough handsorting, but it is usually present with the stream-tin. As Prof. Schaeffer says, it cannot be separated by ordinary concentration; and while, as declared by Prof. Blake, its columbic acid may not unite with the tin in any form, yet its iron and manganese oxides may be reduced, and thus lower the quality of the tin produced, as is also the case when the smelting charge contains wolfram. To determine the effect of columbite in the ordinary potassium cyanide assay, there were assayed at the Dakota School of Mines four samples containing different proportions of columbite. The results, published in the report of the school for 1888, seemed to indi-

Jan 1, 1889

By J. D. Doherty

A. R. POWELL*—Mr. Doherty has outlined in a most thorough manner valid arguments for the development of an industry in this country making syn. thetic liquid fuels from coal. No thoughtful person will dispute the statement that it is essential to carry on fundamental and applied research and acquire engineering "know-how" by the erection and operation of two or three large plants in the near future. Considerations of national security indicate that this should be done, irrespective of any temporary present surplus of natural petroleum. It is the belief of the discusser and of many others interested in coal technology that our energy picture of the future will include an increasing utilization of coal directly, without any conversion to liquid fuel, as a source of energy. A fact that is sometimes forgotten is that petroleum fuels have often been cheaper than coal in many locations and over long periods of time, and this price factor has been of great importance in expanding the use of petroleum fuels at the expense of coal. Synthetic liquid fuel made from coal must necessarily be several times as costly as the coal from which it is made, and this fact alone will have a profound effect on the future energy pattern of our country. This complete change in the economic relationship between solid and liquid fuels will lead to the substitution of coal itself for many uses now supplied by the relatively cheap petroleum fuels. From the standpoint of conservation of our natural resources, the substitution of coal itself for liquid fuels wherever possible when the age of synthetic liquid fuel arrives is also logical. At least 50 pct of the energy of coal is lost during conversion to liquid fuel. Nor is this com-pensated for by a higher utilization effi-ciency of the liquid fuel in most cases. For example, modern steam-boiler plants can operate at equal fuel efficiencies with either coal or fuel oil.

Jan 1, 1950

By W. H. Andrews

THE constantly increasing consumption of Portland cement in the State makes the above subject of partlcular interest at this time. The increasing demand is due to the rapid settling of the country and the fact that new uses are being found frequently for the above named commercial article. The industry is one that is bound to grow as the population increases, and this being the case, it may be well ,it this time to consider briefly- the matter of the chemical and physical com-position of proper raw materials. A cement mixture is one that contains approximately 75 per cent. carbonate of lime, 15 per cent. Silica, and 5 to 7 per cent. alumina, and iron oxides; the other elements being magnesium carbonate and small quantities of the rarer elements general associated with limestone deposits. It call be readily seen from the above composition that it is possible to build up this mixture from a number of different materials. First.-A rock high in carbonate of lime can be mixed with clay or shale in such proportions as to bring about the desired composition ; the chief difficulty in the building up of such a mixture is that it is hard to find a clay or shale in which the silica-alumina, ratio lies .between 4 to 1 and 3 to 1 and at the same time shows physical characteristics which will make certain its adaptability to the practical manufacture of Portland cement. Very often clays or shales are found which are right chemically but contain large quantities of grit or free silica. Such clays or shale must be ground to extreme fineness in the mixture in order to make the silica and alumina combine with the lime when the mixture is burned. On the other hand, clays or shales are often found that have the proper physical characteristics but in which the amount of alumina, is too great.

Jan 9, 1913

By Herbert Wilson

THIS topic was discussed at the meeting in St. Louis in September, 1917, and at the meeting in New York in February last, but in the interval the war has accentuated in measurable degree the necessity for considering human relationship, not only as between nations, or in the treatment of our returning soldiers, but with respect to the relations between labor and capital in industry. It is my firm conviction that no other subject will have so large a place in industrial and political life during the next decade as this. Heretofore, the employer has been so engrossed with the financial, mechanical, and technical aspects of his business that he, has been willing to muddle through &apos;his relations with labor as best lie might and, on the other hand, the laborer has been so engrossed in his endeavors to secure a livelihood under whatever living and working conditions might be offered him that he has given little thought to his relations to his employer, until some misunderstanding has ended in disagreement and strike. No thinking man doubts that were the machinery available for friendly, personal, face-to-face consideration of the problems confronting employer and employee, there would he fewer disagreements, fewer strikes, and a better and more settled industrial situation. The necessity for some such medium for exchange of views has resulted in the organization of labor and, in some measure, of capital. Each party, engrossed only in defending its own viewpoint, has generally tried to gain its point by might rather than by right. Gradually, however, the representatives of both elements are beginning to appreciate that when the machinery for bringing them together in friendly communion is available their differences frequently settle themselves. There remain yet vast numbers of employers and of employees who are not organized and to whom the opportunity of friendly discussion of differences is not available; for these the machinery should he provided.

Jan 1, 1919