Search Documents

By D. P. Harris

This paper surveys a few of the quantitative exploration models that might be of interest to an ex-plorationist seeking to apply methods of operations research to mineral exploration. A general development of each model is presented, and the model is evaluated relative to the exploration activity. Finally, a philosophy of exploration and mineral resources is presented, and a possible exploration strategy incorporating concepts of some of these models consistent with this philosophy is proposed. The high cost of conducting an effective exploration program has generated an increasing interest in methods of optimizing the allocation of the resources of a firm engaged in mineral exploration. As a step towards this, mathematical models have been formulated which are designed to quantify those variables of mineral exploration in such a manner that they can be integrated with all phases of the firm's operations so as to optimize its profit objective. QUANTITATIVE MODELS General: Exploration models express at least two concepts: mineral occurrence and effectiveness of search. In simplest terms, an exploration model might be formulated mathematically as follows: P(X) = F(X) . G(X), where P(X) = the unconditional probability of discovery of X deposits, F(X) = the probability of occurrence of X deposits, and G(X) = the probability of discovery of X deposits, conditional upon their existence in the search area. With these general models as a basis of reference, some of the specific exploration models are examined below. The Allais Model: DEVELOPMENT - M. Allaisl performed the first study in which a philosophy of exploration was formulated into a probability framework. His objective was to estimate the economic profitability of the exploration of the Algerian Sahara. Allais divided the Algerian Sahara into blocks of land (called cells) 10 km square and defined the random variable, X, as the number of mining districts per cell. Thus, F(X) would describe the probability of 1, 2, or n mining districts occurring within any cell of the search area. Allais reasoned that his best information as to the form of the distribution, F(X), was the number of mining districts per cell that had been found in well explored areas in the world, such as the Western States of the U.S. He found that the Poisson function produced a reasonably good fit to the distribution of districts in these explored areas: where? is a parameter, such as the average number of districts per cell. Thus, by determining the value

Jan 1, 1968

By V. I. Purcell, S. C. Sun. R. E. Snow

A study including effects of 7) pH value, 2) fatty acid collector, 3) fuel oil, 4) interfering ion, 5) particle size, and 6) operational variables. Test results indicate feasibility of fatty acid flotation under certain restrictive conditions. FATTY acids have been used as standard collectors for floating the matrix1-8 but not the leached zone phosphate ores. After a series of investigations, Davenport9 and Tarbutton10 concluded that the Florida leached zone ores tested were unamenable to fatty acid flotation and must be upgraded by floating the siliceous gangue with Armac-T as collector. The cationic flotation was estimated11 to cost almost ten times as much as a fatty acid process that would ideally give the same flotation grades and recoveries of phosphates. Mineralization: Extensive deposits of leached zone aluminiferous phosphate occur in Florida."= The ore sample used for this work was obtained from the Virginia-Carolina Chemical Corp., Clear Springs area, Florida. The ore is a potential source of uranium and aluminum as well as phosphorus. Since the uranium and the recoverable aluminum are contained in some of the phosphate minerals, an upgrading of phosphate results in a corresponding enrichment of both uranium and aluminum. The phosphate minerals in the ore are primarily pseudo-wavellite, millisite, and carbonate fluorapatite, with a minor amount of wavellite. Quartz and clay are the common gangue minerals, quartz being predominant. Others present in small amounts are ilmenite, hydrated iron oxides, staurolite, monazite, and zircon. Experimental Procedures: After being dried to less than 1 pct surface moisture the material was dry-ground in a Hardinge conical ball mill to —6 mesh. The ground product was classified into 6/20, 20/200, and —200 mesh size fractions. On the basis of Table I, the coarse and fine size fractions were considered as phosphate concentrates, because of their high phosphorus contents. In contrast, the 20/200 mesh fraction, which was low in phosphorus, was used as the flotation feed. All the flotation tests, unless otherwise stated, were performed in a laboratory Fagergren machine under the following conditions: 1) 400 g of solid feed for each test, 2) 2000 rpm impeller speed, 3) 8.9 pH and 4-min conditioning, and 4) 3-min flotation. The procedure used for the quantitative bubble pick-up tests has been described previously.18

Jan 1, 1958

By W. T. Stuart

THE increased demand for iron ore has necessitated a re-examination of ore-bearing lands on which the presence of water previously has indicated hazardous and expensive operating conditions. In view of the importance of iron ore production to the national economy and defense, the Ground Water Branch of the U. S. Geological Survey, in cooperation with the state of Michigan, began a study of mine drainage in the Iron River district in 1945, and later extended the work to the Marquette district. The purpose of these studies was to define the principles involved in the movement of surface and ground water toward the mined areas, with the hope that the information obtained in the research would lead to the development of methods of water control and to a reduction in the total mining costs. Not only are the direct costs of drainage increasing, but also the indirect operational costs of working a wet mine are becoming a larger proportion of the total mining costs. For some wet mines the direct costs of pumping and drainage may range from 35 to 40Ø per ton of ore produced, but the indirect costs due to handling wet ore and controlling the water may be five to ten times this amount. The methods of study were formulated as the work progressed, and inasmuch as they were the first large-scale studies of their kind, they should serve as a guide for the solution of similar problems in other mining areas. The Iron River district was chosen for a pilot study because in this district the longest records of mine pumpage and water-level observations were available, including, as they do, the records for the Homer mine of the M. A. Hanna Co., where pumping from surface wells began in 1930. The results of the first investigation by the Michigan Department of Conservation have already appeared." The first section of the report on a similar study of the Marquette district, which was started in 1948, will be published this year. Methods of Study In an effort to reduce the flow of water into the mine workings in the Iron River district, about 4500 gpm was pumped from the bedrock being mined and about 9000 gpm from the glacial overburden. In the Marquette district in the vicinity of Ishpeming and Negaunee, about 5000 gprn was pumped from the bedrock and about 4000 gpm was pumped from the glacial overburden. Where the water was pumped only from the bedrock, the rate of pumping ranged from a few hundred gallons per minute in the dry mines to many hundred gallons per minute in the wet mines. In each district, pumping from the overburden was localized on a few properties where costly pumping installations had been made and the expenditures for power had been large. In each district a comprehensive ground-water investigation was made of the whole area, involving the collection and interpretation of all the available data bearing on the source and quantity of water to be controlled. Although it is not the purpose of this paper to discuss the methods of making a ground-water investigation, it should be pointed out that a drainage study follows a pattern of engineering analysis that determines the occurrence, source, movement, disposal, and quantities of water involved. The investigation in the iron-mining districts of Michigan began with the construction of a map of the buried bedrock topography. Because the ground-water reservoirs occupy the low points in the bedrock basins, this map gives information concerning their areal extent, depth, shape, and degree of interconnection. The depth to water in the drillholes and wells indicates the altitude to which the ground-water reservoirs are filled, and the logs of the material penetrated in the drillholes and wells indicate the general character of the materials filling the reservoir. The slope of the ground-water surface indicates the direction of flow through the reservoir, the water movement being from the points of higher altitude to points of lower altitude. By analysis of the rise and fall of the ground-water levels in response to additions of water through recharge and to changes in the rate of discharge through pumped wells, estimates of the total quantity of water in storage and of the rate of flow through the reservoir

Jan 1, 1952

By L. M. Pidgeon, K. T. Aust

There has been considerable interest in the possible use of titanium in magnesium alloys.' Zirconium has shown some promise in this connection2 and its general similarity with titanium suggests that the latter might act in a similar manner. A literature survey revealed that quantitative data on the Mg-Ti system was unavailable. Several patents3 have claimed that titanium additions from 0.2 to 4 pct to magnesium alloys were possible, but no mention was made as to the form in which the titanium existed in the alloy. Kro114 succeeded in introducing only traces of titanium into magnesium by bubbling TiCl4 through the metal under argon or by reacting it with sodium titanium fluoride. The application of theoretical data given by Carapella5 based on Hume-Rothery's principles, involving atomic size factor, crystal structure, valency and the electro-chemical factor, suggests that a Mg-Ti alloy is a favorable case, and the system appeared to warrant experimental examination. Experimental Procedure and Results THERMAL ANALYSIS If titanium is appreciably soluble in magnesium, a change in the melting point of the magnesium might be detectable using standard cooling curve methods. Magnesium was melted in graphite crucibles under an argon atmosphere, the assembly being enclosed in a silica tube. Graphite thermocouple protection tubes served also to stir the melts. The apparatus was very similar to Fig 1, with the addition of a refractory and baffle system to prevent undue heat losses from the top of the crucible. Chromel-alumel thermocouples were calibrated using Al of 99.97 pct purity. Dominion Magnesium Limited sup- plied redistilled high purity magnesium of the analysis given above. Titanium was added in three different forms: 1. Titanium powder —100 mesh, from the Titanium Alloy Manufacturing Co., Niagara Falls, N. Y. 2. Sheet titanium from the U.S. Bureau of Mines, produced by Mg reduction of TiCl4. 3. Magnesium —50 pct titanium master alloy from Metal Hydrides Inc., Beverly, Mass. The melting point of the high purity magnesium used was measured experimentally as 651.0°C. More than a dozen tests were conducted using titanium from the three sources referred to above, in calculated additions up to 20 pct titanium, at temperatures between the melting point and 1000°C and holding periods up to 6 hr. In no case was evidence obtained of solubility of titanium in magnesium, using inverse-rate and time-temperature curves. The melting point of the magnesium was unchanged within the accuracy of measurement, namely -+0.5°C; and no other thermal arrests were detected. Metallographic investigation of the thermal analysis billets indicated that the titanium additions were apparently mechanically entrapped in the magnesium in segregated areas. Consequently, these samples were not analyzed for titanium. The master alloy proved to be a mechanical mixture of titanium particles in a magne- sium matrix. These results indicated that the titanium solubility, if such existed, could not be obtained by the usual thermal methods. X RAY DIFFRACTION INVESTIGATION In an effort to detect solubility of titanium in magnesium, samples were investigated using both the Debye-Scherrer and the Focusing Back-Reflection methods. Filings from samples of the thermal analysis billets and from pure magnesium were annealed in argon one hour at 350°C to relieve mechanical strain. Measurements made of the interplanar spacings showed no difference between the Mg-Ti samples and pure magnesium. The interplanar spacings could be measured to within 0.0002A, and the greatest variation found was 0.0004A, in the back-reflection method. The diffraction lines for magnesium were not shifted by the titanium additions indicating that the solid solubility of titanium in magnesium is of a very low order—less than 0.5 pct. From both diffraction methods, a d or interplanar spacing of 0.817A was obtained for the redistilled high purity magnesium. This latter value is not given in the standard X ray diffraction cards for magnesium metal or vacuum distilled magnesium. Theoretical calculations for a close-packed hexagonal space lattice for magnesium indicate that the planes {2134) should give a line which was found. The relative intensity for this reflection at 0.817A is slightly less than that at 0.870k for magnesium. SOLUBILITY OF TITANIUM IN LIQUID MAGNESIUM The Mg-Mn system was examined by Grogan and Haughton6 who were

Jan 1, 1950

By A. H. Redfield

BITUMENS have been defined by Abraham1 as substances of variable color, hardness, and volatility; composed principally of 'saturated hydrocarbons, substantially free from oxygenated bodies, sometimes associated with mineral matter; the nonmineral constituents being fusible and largely soluble in carbon disulphide. The principal bituminous substances other than petroleums known to commerce are: (1) native asphaltites, such as gilsonite, grahamite, and glance pitch, distinguished by their hardness and relatively high fusing point; (2) native asphaltic pyrobitumens, such as wurtzilite, distinguished by their infusibility and comparative insolubility in carbon disulphide; (3) mineral waxes, such as ozokerite, distinguished by their high content of crystallizable paraffins; (4) native asphalts, containing varying amouqts of mineral matter, distinguished by the comparative absence of crystallizable paraffins; and (5) bituminous residues obtained from the distillation of petroleum. GILSONITE Gilsonite, a black native asphaltite 98 to 99.9 pct pure, characterized by a hardness of 2 (Mohs), a specific gravity of 1.01 to 1.10, and melting point of 230° to 400°F (K and S), is mined commercially only in northeastern Utah. It occurs in parallel, almost vertical veins, from a few inches to 18 ft wide and 8 to 30 miles long, that cut across the Tertiary limestone and shale of the broad Uinta Basin. The bitumen is believed to have been distilled by heat from oily material in the underlying Green River shale. At the Rainbow mine of the American Gilsonite CO.,† the gilsonite, formerly extracted in an opencut by a system of slopes and benches, is now mined by shafts and horizontal drifts. Little timbering is required. The mining methods of the Raven Mining Co., Chicago, and of the American Asphalt Association and the Utah Gilsonite Co., both of

Jan 1, 1949

By W. E. C. A. B. Eustis

(Read at the Philadelphia Meeting, February, 1878.) IN September last I had my attention called by Mr. R. G. Leckie to a deposit of nickel in the township of Orford, province of Quebec. In many ways it has proved to be a subject of great interest. As this ore is, as far as I can learn, entirely new in mineralogy and metallurgy, it has seemed to me that it would be a matter of interest to the Institute to have laid before it, in a short paper, the peculiarities I have met with in studying it. This deposit of nickel was first described by Dr. T. Sterry Hunt, our President, in the Geology of Canada, 1863, p. 738, in the following terms : "The general diffusion of nickel throughout the magnesian rocks of the Quebec group has been already noticed. It has, however, never been met with in any considerable quantities in these rocks, although workable deposits of its ores may reasonably be looked for

Jan 1, 1878

By W. E. C. Eustis

In September last I had my attention called by Mr. R. G. Leckie to a deposit of nickel in the township of Orford, province of Quebec. In many ways it has proved to be a subject of great interest. As this ore is, as far as I can learn, entirely new in mineralogy and metallurgy, it has seemed to me that it would be a matter of interest to the Institute to have laid before it, in a short paper, the peculiarities I have met with in studying it. This deposit of nickel was first described by Dr. T. Sterry Hunt, our President, in the Geology of Canada, 1863, p. 738, in the follow ing terms: " The general diffusion of nickel throughout the magnesian rocks of the Quebec group has been already noticed. It has, however, never been met with in any considerable quantities in these rocks, although workable deposits of its ores may reasonably be looked for

Jan 1, 1879

Mr. Joseph P. GAZZAM,Germiston, Transvaal, So. Africa (communication to the Secretary*) :—About fourteen years ago, in southeastern Missouri,I used a method for the wet determination of lead which closely resembles the modified sulphate-chromate method described by Mr.. Guess. The principal difference, however, is, that after dissolving the lead chromate in hydrochloric acid, the chromic acid is determined by means of a standard solution of ferrous sulphate. The method, which I believe is still in use in southeastern Missouri, was found to be convenient and accurate for the determination of lead in the ores and various products of the mills and furnaces in that district, but it was never used for complex ores. A number of determinations of lead in mill-tailings were made in the year 1891; a few of these results are given in Table I. Table I.—Determinations of Lead in MilL-Tailings by Wet Assay.

Jan 1, 1905

By Sherman L. Pease

An inexpensive and relatively rapid method that can be used by field crews is described. Fluid movement is determined by releasing a tracer (dye) in the well at a predetermined level and, after an interval of time, sampling the well fluid at another level. The testing equipment consists of a combined crusher and sampler unit that is run into the well on a wire line. The rate of movement can be calculated from time-volume relationships. Description of Method It is often desirable to determine whether there is occurring any transfer of fluid from point to point in a shut-in well, and, if so, to measure the rate of movement. When it is desired to examine a large number of wells for possible "thief" sands, the time and expense will be considerable unless the method used is inexpensive and rapid. After experimentation with several possible solutions to the problem, the Production Department of the Shell Oil Co., Inc., developed the apparatus described herein, which has proved satisfactory. Routine operations with it can be carried out by field production crews with a minimum of technical supervision and with negligible investment in equipment. The method is based upon releasing a suitable tracer in the well fluid at a known level, and recovering a sample of well fluid at another level after a measured interval of time. Repetition of this process with different time intervals between release and sampling gives the necessary data. For purposes of illustration, the setup for measuring migration of fluid in an upward direction is described in the following paragraphs. The arrangement of equipment is shown diagrammatically on Fig. I. The elements of the combination unit are the tailpiece, the crushing device, the spacer and the sampling device. The lengths of the tailpiece and spacer are varied to place the crushing and sampling devices in the desired positions in relation to the sands being tested. The crushing device breaks the glass bottle containing the tracer when the tailpiece strikes the bottom of the well and the tension on the sand line is slackened. Because of the open construction of the crushing device, the tracer is quickly and completely disseminated in the well fluid. The sampling device is a suction bailer, which obtains a sample of the fluid surrounding the perforated nipple just before the unit is picked up off bottom. The sample is retained in the barrel by the ball valve for examination at the surface. Normally, on the first run into a well, the sample is obtained near the releasing point of the tracer, and thereafter samples are taken near the base of the upper sand if migration is indicated by the dilution or absence of the tracer in the initial sample. The length of the time interval between the releasing of the tracer and the sampling of the well fluid is varied for successive runs, attempting first to establish the rate within limits and then to define it more accurately by additional runs if necessary.

Jan 1, 1946

By Sherman L. Pease

An inexpensive and relatively rapid method that can be used by field crews is described. Fluid movement is determined by releasing a tracer (dye) in the well at a predetermined level and, after an interval of time, sampling the well fluid at another level. The testing equipment consists of a combined crusher and sampler unit that is run into the well on a wire line. The rate of movement can be calculated from time-volume relationships. Description of Method It is often desirable to determine whether there is occurring any transfer of fluid from point to point in a shut-in well, and, if so, to measure the rate of movement. When it is desired to examine a large number of wells for possible "thief" sands, the time and expense will be considerable unless the method used is inexpensive and rapid. After experimentation with several possible solutions to the problem, the Production Department of the Shell Oil Co., Inc., developed the apparatus described herein, which has proved satisfactory. Routine operations with it can be carried out by field production crews with a minimum of technical supervision and with negligible investment in equipment. The method is based upon releasing a suitable tracer in the well fluid at a known level, and recovering a sample of well fluid at another level after a measured interval of time. Repetition of this process with different time intervals between release and sampling gives the necessary data. For purposes of illustration, the setup for measuring migration of fluid in an upward direction is described in the following paragraphs. The arrangement of equipment is shown diagrammatically on Fig. I. The elements of the combination unit are the tailpiece, the crushing device, the spacer and the sampling device. The lengths of the tailpiece and spacer are varied to place the crushing and sampling devices in the desired positions in relation to the sands being tested. The crushing device breaks the glass bottle containing the tracer when the tailpiece strikes the bottom of the well and the tension on the sand line is slackened. Because of the open construction of the crushing device, the tracer is quickly and completely disseminated in the well fluid. The sampling device is a suction bailer, which obtains a sample of the fluid surrounding the perforated nipple just before the unit is picked up off bottom. The sample is retained in the barrel by the ball valve for examination at the surface. Normally, on the first run into a well, the sample is obtained near the releasing point of the tracer, and thereafter samples are taken near the base of the upper sand if migration is indicated by the dilution or absence of the tracer in the initial sample. The length of the time interval between the releasing of the tracer and the sampling of the well fluid is varied for successive runs, attempting first to establish the rate within limits and then to define it more accurately by additional runs if necessary.

Jan 1, 1946

By R. G. Vardiman, M. R. Achter

THERE has been interest recently in the conditions under which dislocation pipe diffusion may be observed. In order to extend the measurements to temperatures below Tm/2, where pipe diffusion becomes more important, a chemical sectioning technique was developed for silver single crystals which makes possible the removal of layers of 100A or less. The procedure is briefly as follows. Silver single crystals of 99.995 pct purity were cut in the form of discs t by 4 in., electropolished, and electropolated with Ag110 to about 1000A thickness. The thickness was determined by calibrating the activity with the weight of heavier platings, up to 10,000A. Both diffused and undiffused samples were sectioned in a two-step process. Reaction with a solution of iodine in alcohol formed a thin, even layer of AgI, which was then dissolved in a KCN solution. The reaction rate of the iodine solution varied slightly over a period of time, so that the thickness of the stripped layers, while quite even and regular for a given specimen, ranged from 65 to l00W for different specimens. This variation was checked by using a thickly plated standard with each run. Layer thickness was determined from undiffused samples by the point where the layer activity drops to half the maximum. This maximum intensity also provides, with appropriate corrections, the initial concentration per layer co. Because of the small penetration distances, it is necessary to use the exact solution of Fick's law for a source of finite thickness.' For a plating of thick- where c is the concentration at depth x. flj the error function, D the apparent diffusion coefficient, and t the time. The diffusion coefficient was obtained from the concentration-penetration data by extrapolating to x = 0 where c/co = erf h/2(Dt)1/2 Enough points were taken to impart confidence in the accuracy of the intersection, generally about ten layers. Four temperatures were used as in Table I. For best accuracy, t and h were chosen to give values of the parameter (Dt)1/2/h between 1.0 and 1.7. A typical concentration-penetration curve is shown in Fig. 1. The diffusion coefficients calculated from Eq. [I] are plotted in Fig. 2. For comparison, the high-temperature data of Tomizuka and sonder 2 which go down to 630°C are plotted as the solid line 2(a) from their expression D = 0.40 exp (-44,090/RT). Also for comparison, the lowest temperature point of Hoffman and Tumbull3 is plotted. It is apparent that our data diverge appreciably from the high-temperature extrapolation by 373°C. A better straight line fit for the low-temperature portion is obtained by subtracting the extrapolated volume diffusion coefficient from the apparent. or measured coefficient, and plotting the difference, curve (h) of

Jan 1, 1970

By Ernest P. Hall

At the SME Fall Meeting held in Phoenix, Ariz. last October, Ernest P. Hall, addressing an Air and Water Pollution session, noted that water pollution caused by acid drainage from bituminous coal measures had begun long before recorded history. "Until recently," he said, "man did not begin to understand the physical phenomena which took place to cause [it] and even today he does not know what can be done to prevent it." CAUSES "It is known from the reports of early explorers that drainage from bituminous coal measures was causing water pollution before coal mines were opened on this continent. They noted the nature of the polluted water in the runs and creeks and predicted the presence of substantial deposits of coal based on the appearance and character of the water. Even today, polluted water drains from virgin coal areas which have not been touched by mining machines," Mr. Hall said.

Jan 1, 1966

By W. C. Hagel

In 1952, Hauffe and pfeiffer1,2 reported that parabolic rates of nickel oxidation are decreased by factors of two and four at 1100° and 1000°C, respectively, when Li2O vapor is present. Hauffe 's3 explanation was that monovalent lithium enters the crystal lattice of p-type NiO to decrease cation-vacancy concentration and, hence, diffusion of Ni2+ ions across the growing oxide. After first succeeding in adding lithium directly to molten nickel, the purpose of this investigation was to determine whether alloyed lithium is a more effective oxidation inhibitor than the external vapor. Seven 650-g heats were prepared by melting carbonyl nickel inductively under 1 atm of argon. Various amounts of lithium were added by dropping small chunks into the melt. Only about 10-pct recovery was achieved with the remainder lost by spattering and volatilization. Nominal and actual

Jan 1, 1965

By R. W. Raymond

THE Brüclrner roasting-cylinder is well known as an apparatus which has done good work in the desulphnrization, particularly of refractory silver ores, in the western districts of this country. A paper by Mr. J. M. Locke, of Cincinnati, describing the cylinders, as constructed by Messrs. Lane & Bodley, in that city, may be found at p. 295, vol. ii., of the Transactions of the Institute; and a paper by Mr. N. H. Cone, vol. iv., p. 226, gives an account of their operation in Colorado. The purpose of the present paper is to present an .improved construction, designed by Mr. Brückner. This is clearly shown in the accompanying plate, which scarcely needs explanation. It will be seen at once that this construction involves two cylinders, instead of one. Mr. Brückner thinks that three cylinders might be better yet, as securing an exact mechanical reproduction of the work of the well-known three-hearth Fortschaufelungsofen, the most perfect of the reverberatories in which delicate roasting is performed with hand-labor. THE APPARATUS. Erection of the Cylinders.—Although the cylinders may he put lip at any locality, or added to existing works, it is preferable, if possible, to choose the site on a hill sloping naturally, say about 30' or 33. Two excavations are made, one 8 to 12 feet higher up than the other; and each is protected by a wall with a batter of about 1 inch to the foot, to prevent slides of stone and earth. Each cylinder being 20 feet long and 7 feet in diameter, the total excavation should be 60 to 70 feet along the hill, and 15 to 25 feet wide. On each level a building is erected 35 feet long by 20 feet wide and 12 feet high, with the roof containing a ventilator against the hill. When both buildings are on the same level, there should preferably be a solid frame-work of very heavy timber, to carry the four rollers which bear the upper cylinder. The four rollers carrying the lower cylinder should preferably rest on two very heavy pieces of timber, strongly braced together and laid to their top in a foundation made of stone or brick and cement. Foundations are necessary only under each two opposite rollers, but they must be made carefully,

Jan 1, 1886

By Frank A. Crossley

The work described has one serious shortcoming: grain size was not monitored during heat up to the temperature (1675°F) of isothermal anneal. The chief obstacles to p grain growth in titanium a-ß structures are the a grains. Heating a structure such as that shown in Fig. 1 to a temperature close to ß transus causes dissolution of a grains in order to adjust the a/ß ratio, compare Figs. 1 and 2. During this process there is a concomitant growth of the ß grains—otherwise ß grains would have to be nucleated in order to adjust the a/ß ratio. When the annealing temperature is reached the a/ß ratio stabilizes and this initial phase of ß grain growth ceases. After an incubation period growth resumes as described. Some 0 grain boundaries can be clearly seen in Fig. 1. (Skilled metallography commonly produces photomicrographs which show more structural detail than direct observation.) These boundaries suggest that the average ß grain size is approximately 0.002

Jan 1, 1970

By Alexander Knoll, Dwight L. Baker

THIS paper is a report on work undertaken to investigate the results and conclusions of Ravitz and Porter1,2 that galena freed of surface oxidation products and lead carbonate ("clean" galena) is waterrepellent, and that the action of xanthates in flotation is the action of a cleansing agent, enabling oxidized galena particles to expose a pure lead sulphide, water-repellent surface. The apparatus, in construction and use, was essentially that of Ravitz and Porter. The only significant modification introduced by the present authors was the substitution of a three-necked flask for the flotation cell as the "reaction vessel." Our procedure was to place 50 grams of freshly ground, minus 200-mesh galena in the reaction vessel, sweep out all molecular oxygen from the system with oxygen-free nitrogen, and proceed to wash the galena surface free of its oxidation products with repeated small portions of (I) ammonium acetate (500 c.c. of water, 200 grams of ammonium acetate) or (2) ammonium chloride, hydrochloric acid (2 liters containing 200 grams of ammonium chloride and 25 c.c. Of 1.18 sp. gr hydrochloric acid). The galena was next washed with many 100-c.c. portions of oxygen-free, distilled water. The galena was finally considered free of soluble salts when wash water that had been in contact with the mineral for at least 48 hr.* gave negative tests for: (x) lead ion with sulphide; (2) chloride with silver ion; (3) acetate with cuprous chloride, sodium chloride; and (4) ammonium ion with Nessler's reagent. Next 500 c.c. of potassium ethyl xanthate solution, free of dissolved oxygen, was run onto the "clean" galena particles. For this system there were determined: I. The wetting properties of the clean galena particles by shaking the reaction flask and noting the degree of mineral collection at the liquid-air interface. This was, of course, simply a qualitative test, but it proved adequate for our purpose. 2. The removal of xanthate ion from the potassium xanthate solution on being shaken with the "cleansed" mineral. Xanthate concentrations were determined by iodine titration according to the methods of Taylor and Knoll.3 3. The pH of the xanthate solution after having been shaken with the "cleansed" galena. The pH was determined colorimetrically.4 The results of five experiments of the type mentioned above are given in Table x.

Jan 1, 1941

By Alexander Knoll, Dwight L. Baker

THIS paper is a report on work undertaken to investigate the results and conclusions of Ravitz and Porter1,2. that galena freed of surface oxidation products and lead carbonate ("clean" galena) is water-repellent, and that the action of xanthates in flotation is the action of a cleansing agent, enabling oxidized galena particles to expose a pure lead sulphide, water-repellent surface. The apparatus, in construction and use, was essentially that of Ravitz and Porter. The only significant modification introduced by the present authors was the substitution of a three-necked flask for the flotation cell as the "reaction vessel." Our procedure was to place 50 grams of freshly ground, minus 200-mesh galena in the reaction vessel, sweep out all molecular oxygen from the system with oxygen-free nitrogen, and proceed to wash the galena surface free of its oxidation products with repeated small portions of (I) ammonium acetate (500 c.c. of water, 200 grams of ammonium acetate) or (2) ammonium chloride, hydrochloric acid (2 liters containing 200 grams of ammonium chloride and 25 c.c. of 1.18 sp. gr. hydro chloric acid). The galena was next washed with many 100-c.c. portions of oxygen-free, distilled water. The galena was finally considered free of soluble salts when wash water that had been in contact with the mineral for at least 48 hr.* gave negative tests for: (I) lead ion with sulphide; (2) chloride with silver ion; (3) acetate with cuprous chloride, sodium chloride; and (4) ammonium ion with Nessler's reagent. Next 500 c.c. of potassium ethyl xanthate solution, free of dissolved oxygen, was run onto the "clean" galena particles. For this system there were determined: I. The wetting properties of the clean galena particles by shaking the reaction flask and noting the degree of mineral collection at the liquid-air interface. This was, of course, simply a qualitative test, but it proved adequate for our purpose. 2. The removal of xanthate ion from the potassium xanthate solution on being shaken with the "cleansed" mineral. Xanthate concentrations were determined by iodine titration according to the methods of Taylor and Knoll.3 3. The pH of the xanthate solution after having been shaken with the "cleansed" galena. The pH was determined colorimetrically.4 The results of five experiments of the type mentioned above are given in Table I.

Jan 1, 1941

By Michel Elle, John Chipman

The equilibrium of gaseous H20-H2 mixtures with liquid iron-columbium alloys in the range 0.2 to 2.4 pct Cb shows that the activity coefficient of oxygen is strongly diminished by Cb. The oxide in equilibvium with the melt is identified as CbO2. The equi-librium constant at 1600 deg C is [%Cb][fo. % 0]2 = 2.9 x 10-4 where log fo= —0.14 [%Cb]. The deoxidizing power is comparable to that of vanadium, COLUMBIUM (niobium) is finding increasing use as an alloying element in steel. It forms several stable oxides and is removed from the steel bath by oxidizing slags. The specific oxide formed in steel-making is not known although Sazanov snd Shvarts-man,' in their study of its partition between slag and metal, have assumed this to be Cb2O5 It is the purpose of this study to determine its deoxidation equilibrium at 1600°c, the nature of the oxide formed and the interaction between columbium and oxygen in the melt. The investigation was based on the reaction H2 + O=H2O; Kl=ph2o/(pH2[%O]) [1] in which 0 signifies oxygen dissolved in the liquid Fe-Cb alloy. The method and equipment of recent studies2,3 were utilized. In brief, the molten alloy, contained in a small crucible, is held in a controlled mixture of steam, hydrogen, and argon until equilibrium is reached. It is then cooled quickly in a stream of helium and analyzed for columbium and oxygen, the latter by vacuum fusion.4 The solubility of the oxide in liquid iron is determined by visual observation of scum formation on the surface of the melt. Crucibles of MgO proved unsatisfactory because of partial reduction at the metal interface. Pure A12O3 crucibles were heavily blackened by the melt and could not be used at high concentrations of columbium. Silica crucibles were more satisfactory but these introduced some silicon into the melt thus necessitating an uncertain but small correction for its effect on the activities of the other solutes. In silica it was possible to observe the scum formation when the melt became saturated and there was no apparent reaction between scum and crucible. The procedure for saturated melts was as follows. The alloy charge composed of electrolytic iron and columbium grain was melted and held at constant temperature. The gas ratio H2O:H2 was progressively increased by raising the saturator temperature until a point was reached at which a bright film appeared on the surface and covered it completely. This film could be dissolved by raising the temperature of the melt and it reappeared when the temperature was lowered. Under a partial film covering, utilizing bare areas for temperature measurement, the melt was brought to equilibrium with the atmosphere by holding at temperature for about 1 hr as suggested by Dastur.5 INTERACTION IN THE MELT Several experiments were made without columbium to establish a base in silica crucibles. The results are shown in Table I. Except for one run, they agreed well with Floridis1 comparable results in other crucibles. The value of log K1 is taken from Table I as 0.58. This is slightly larger than Floridis' result, probably because of less elaborate safeguards against thermal diffusion. Results obtained in the Fe-Cb-0 series in which no scum formed are shown in Table 11. The equilibrium ratio Kl is defined as ph2o/(ph2[%O]). It is related to the equilibrium constant K1 as follows:

Jan 1, 1962

By W. D. Haentjens, A. P. Pipilen, M. Weintraub, A. A. Orning

W. D. Haentjens (Barrett, Haentjens and Co., Hazleton, Pa.) — The authors are to be complimented on undertaking a project which has little available experimental data. There are so many variables in the hydraulic transport of solid materials that it is difficult to correlate the experimental information from one series of tests into usable data involving other materials or even similar materials but of different size consists. The friction data is of particular interest to those involved in pipeline design. Most such pipelines, however, involve portions which are not level and the effect of sloping or vertical lines might also be considered in extensions of this test work. Pump manufacturers are concerned about criticism resulting from the stated amount of degradation occurring in a pump. The amount of degradation is affected somewhat by pump design and this should be taken into consideration. The pump which was loaned for this work was a modification of a standard medium duty slurry pump. This modification was for maximum particle size, however if minimum degradation is the object, then other design changes would be indicated. Although there is a tendency to be less concerned with degradation in industrial applications, it is nevertheless an important factor in many uses and further studies should be made. In particular, the amount of degradation could possibly be segregated into more classifications, rather than charge some losses to the pump which apparently are occurring in other handling. It seems difficult to evaluate the degradation which occurs in handling the coal into the pump sump and in removing it from the line into the tank. Each handling, of course, contributes some degradation, as does the screening operation itself. These are all charged to the pump, or to the pipe line and pump together; and, although they may be small, they could possibly be evaluated. It is interesting to note the verification of the old rule of thumb of maximum particle size equal to approximately one-third of the pipe size. Our experience has shown size distribution to have an effect on the flow characteristics and if this data is available for the tests which were run, it would be interesting supplementary information. A. P. Pipilen, M. Weintraub and A. A. Orning (Authors' Reply) — In this paper the authors have attempted to outline some of the major factors affecting a rational design for a solids-liquid transport system. They are grateful to Mr. Haentjens for pointing out several other equally important considerations. Pump manufacturers, in general, should be complimented on the strides that have been made in decreasing particle degradation within the pump. Considerable research and a great deal of mathematical analysis is required before pump design in this field can become a science rather than an art, for each system requires a different set of compromises. As Mr. Haentjens indicates, maximum-particle-size handling capability may be inconsistent with minimum degradation; even more important, the rotor profile for the most efficient transfer of energy to the fluid may have to be compromised to reduce particle breakage, for, whenever particle density differs from fluid density, the two phases will have different trajectories. Some evidence of this geometric factor is provided by a cursoy analysis in the Bureau of Mines Report of Investigations now in preparation, where it is indicated that, for the pump used, degradation decreased when the tangential velocity was decreased and when the radial velocity was increased. This relation, itself, is probably a function of particle size and concentration. Some data on particle size distribution, as requested by Mr. Haentjens, will be provided in the Report of Investigations referred to above in addition to that already presented in Table II of the original paper. However, in the limited number of tests it is difficult to distinguish between cause and effect, for not only did the particle size distribution alter the flow characteristics, but, through the medium of degradation, the operating conditions rapidly altered the particle size distribution.

Jan 1, 1965

By Henry M. Howe

THE natural effect of large size should be to increase segrega¬tion. I have previously pointed' to the excessive segregation in many large ingots as tending to confirm this, but I have shown that in case of ingots less than 16 in. square this expected effect of ingot-size is liable to masked by that of other variables. Under these conditions we should expect that if large ingot-size really does tend to increase segregation, this effect would be shown by taking the average of large numbers of cases, so that the effects of these other variables might off-set and cancel each other.

Jan 10, 1909