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By Behrooz Abbasi, Seyedsaeid Ahmadvand, Thom Seal, Babak Azarfar, Bryan Ulrich

Hydro-Jex® is a new enhanced method for heap leach treatment with significantly higher mineral recovery. In this case study at the Los Filos Mine in Mexico, the Hydro-Jex operation is evaluated for heap leach stability. This is pursued by numerical modeling of the heap leach pad stability and well monitoring of the phreatic surface before and after the Hydro-Jex operation. Experimental and numerical results both indicate an improvement in mineral processing under the influence of Hydro-Jex. Numerical results show an insignificant decrease and a significant increase in stability during and after Hydro-Jex injection application, respectively. The integrity of the liner is maintained in both cases. The zonal injection pressure, operationally below the overburden pressure, is found to be negligible compared with the dimensionality of the heap, and stability of the structure is not exposed to any significant risk, even up to 25%above overburden pressure. Furthermore, heap leach factor of safety increases after Hydro-Jex application. This is attributed to breakdown of the water solution build-up and thus a decrease in the phreatic surface depth below the top of the pad. It is suggested that injection wells be drilled, based on thorough geophysical data, in locations where overcompaction of heap material results in water solution build-up and pore pressure enhancement. Compared with traditional heap leaching, the Hydro-Jex technique not only expedites mineral processing by increasing chemical kinetics extraction but also increases the stability of the heap by unclogging drains.

Jun 29, 2020

By C. M. Harrer

The location, features, qualities, and extent of iron occurrences and the associated resources--limestone and dolomite, bentonite, coal-lignite, petroleum and natural gas, power, and water--are evaluated. The results of pioneer beneficiation tests on South Dakota taconite are discussed. In addition, pertinent features of taconite development, cost factors, the Western and Central United States trade area and markets are reported. The State's production of iron ores until 1963 has been small and for purposes other than the manufacture of iron. This investigation disclosed the probability of large resources of taconite in Pennington and Lawrence Counties. The average iron content is 29 percent, and a 65-percent or better iron concentrate might be produced. Ample resources are available for mining and processing taconite. An investment of at least $26 million would be required for a plant capable of turning out 1 million tons of agglomerated iron concentrate per year. The feasibility of such an enterprise is indicated, but intensive investigation and research must be completed to justify such an investment.

Jan 1, 1966

By Tim O’Neil

Upbeat, surprisingly so, might describe the mood at the2002 SME Annual Meeting and Exhibit in Phoenix, AZ. More than 4,000 mineral professionals gathered for three days of education, networking and product perusal. The Annual Meeting featured the theme, “Minerals for the Future@ SME” at the Feb. 25-27 gathering. Meeting attendance reached 4,039along with 479 exhibit booths show-casing 325 companies. Exhibitors found a good mix of industry types:37% from mining, 19% from processing, 20% from manufacturing and 28% from environment, education and government.

Jan 1, 2002

By W. D. G. Hunter

Since 1945 the world's iron ore industry has experienced radical change. This transformation is reflected in new levels of production, consumption and trade, in shits in the location and size of markets, in the tapping of far distant sources of iron ore, and in the emergence of new export centres catering on an increasing scale to ore deficient, importing countries. Within the broad framework of shifting supply/demand relationships, certain operationally meaningful adjustments can be singled out for special mention: 1. The iron and steel industry has undergone vigorous and aggressive expansion, during the post-war period, not only in the capitalist world and among the socialist bloc, but in backward regions as well. New countries have been added to the list of steel producers, while new facilities have been relocated by established steel makers. 2. Overall demand for iron ore has risen rapidly, arid has flowed different channels.

Jan 1, 1964

By M. V. Swain, N. Bristow, R. D. Dukino

During mining, crushing and handling the size of iron ore lumps decreases. Key factors in determining the amount and size of fines that are produced are the mechanical properties of the ore. In a continuation of earlier work on the same ores the mechanical properties of three Australian iron ores from Yandi, Koolan and Mt. Whaleback were determined. In particular, fracture toughness was investigated in greater detail by examining its relationship to crack length using the compact tension test. The elastic modulus and strength of the ores were also determined in flexure and compression. The results were interpreted using Weibull statistics, enabling the ores to be ranked according to strength and elastic modulus. These results, together with data on the mechanical response of the ores to stress and observations concerning the effect of mineralogy on cracking, provide a coherent understanding of the mechanisms involved when the ores fracture

Jun 18, 1905

By Ralph H. Light

The recent surge in demand for uranium in the United States, accompanied by a significant increase in price, has resulted in exploration, mining, and milling of lower grade ores than have been exploited in the past. To sustain production levels of uranium with lower grades of feed requires larger tonnage mill operations. Also, because of recent environmental regulations, mill operations must be prepared to properly contain large tonnages of tailings, and recycle, treat and discharge, or evaporate mill effluents. Thus, the advent of lower grade ores, larger tonnage mills, and environmental considerations has made the cost of milling a critical factor in today's uranium production economics in the United States. Three basic milling methods are employed for extracting uranium from ores: 1. Acid leach, countercurrent decantation, and solvent extraction. 2. Acid leach, resin-in-pulp, and Eluex. 3. Alkaline leach, solid-liquor separation, and precipitation. Vanadium often occurs as a valuable by-product in ore deposits located in the Uravan mineral belt in Western Colorado. Also, lesser amounts of vanadium may occur in ores from South Dakota, New Mexico, and Utah. Vanadium is usually extracted in the acid leach solution with uranium and recovered by solvent extraction after recovery of the uranium. By-product recovery of uranium from phosphoric acid and porphyry copper dump leach solutions is now receiving considerable attention. Pilot plant studies are under way and construction of commercial plants is in progress.

Jan 1, 1977

By E. F. Perry

Simulated weathering tests are used to estimate leachate quality of rocks containing varying concentrations of pyrite and carbonates at mines. This study reports the inter-laboratory results from the third phase of a three part effort to develop a standardized, reproducible simulated weathering test for coal mine overburden. Initial development in phases I and II included evaluation of different test apparatus, effects of particle size, gas composition, leaching frequency and other variables. Phases I and II results are reported by Brady et al (2004) and Hornberger et al (2004). In Phase III, a standard column leaching protocol was used by eight commercial, government and university labs to test five rocks of different lithology, pyrite and carbonate content. Ideally, a simulated weathering test should have three characteristics to be useful in mine drainage studies. These include the capability to produce repeatable results, accuracy in simulating field conditions, and a concise test protocol of weeks to a few months. Simulated weathering, or kinetic testing, produces an effluent that simulates mine drainage composition. This can be beneficial for predicting mine drainage quality in comparison to whole rock analyses. The effluent may be tested for the same water quality parameters as the drainage produced during mining, such as pH, acidity, alkalinity, sulfate, iron, manganese, aluminum or other parameters. If the physical, chemical, and biological conditions of the kinetic tests are representative of those found in the mine environment, leachate composition may be used to estimate the water quality parameter concentrations produced during mining. Hornberger and Brady (1998), and Geidel et al (2000), compiled comprehensive chapters on kinetic tests for mine drainage prediction. These sources included: (1) a chronology and synopsis of scientific literature on these kinetic tests as they have developed over approximately 50 years, (2) discussion of the influence of physical, chemical, and biological processes, and (3) general guidelines for test procedures, data interpretation, and recommendations for further research to develop standard methods. Most of the kinetic test methods in use today were substantially developed and applied more than 40 or 50 years ago, including leaching columns (Braley, 1949), humidity cells (Hanna and Brant, 1962), Soxhlet reactors (Pedro, 1961), and field scale tests (Glover and Kenyon, 1962). . The most commonly used kinetic tests for mine drainage prediction are leaching columns and humidity cells. While these kinetic test methods and others have been used in hundreds of mine drainage studies as shown in Hornberger and Brady (1998) and other references (e.g. Sorini, 1997), they have rarely been used in coal mine permitting by either regulatory agencies or the mining industry. The major impediment to routine use of kinetic test methods is the variation in the design and operation of these kinetic tests, and lack of a standardized, accepted (e.g. by EPA or ASTM) test method. Interpretation and data comparison from different studies can be difficult. METHODS Five rocks of varying lithology, mineralogy, carbonate and pyrite content were collected in bulk from Pennsylvanian age coal measures in Pennsylvania, West Virginia and Indiana. Mineralogical composition of the samples was characterized in detail by Hammerstrom et al (in press) using optical, X-ray diffraction, scanning electron microscopy and electron microprobe methods. Acid Base Accounting (Sobek et al 1978; Skousen et al, 1997, Kania, 1998) was performed on bulk samples for % total sulfur (%S) as a measure of pyrite and potential acid generation, and Neutralization Potential (NP) as an index of carbonate content. A modified NP test, following the procedure suggested by Skousen et al, 1997 was also conducted for four of the five samples. The modified NP test accounts for initial acid consumption, Fe oxidation, and subsequent Fe hydrolysis by the iron carbonate mineral siderite. Siderite, even though it is a carbonate gives zero net alkalinity. Lithologic, Acid Base Accounting and general mineral composition data for the five rocks are shown in table 1 (see Appendix). Whole rock elemental analysis for major and trace elements was conducted on a sub-sample of each rock type. One laboratory was contracted to mix, homogenize, and size the bulk samples and prepare sub-samples for all the participating labs. Splits were sent to eight labs, and each organization was provided a detailed set of instructions for column assembly and leaching procedure. The protocol was developed based on results from phases 1and 2 of this study. The principal features of the column assembly are: a specific composition of particle size by weight (table 2), weekly leaching cycles, and incubation under humidified air containing 10% CO2. Figure 1 shows the column construction. [ ] The particle size distribution of the crushed rock sample is largely an artifact of the crushing process, rather than a natural systems process like the particle size distribution of a soil or an unconsolidated sedimentary deposit. The standardized particle size distribution, shown in Table 2, promotes operational consistency of the weathering test procedure, and provides better control over reaction kinetics. Large amounts of fine particles within specific zones of the leaching columns have been found to impede uniform fluid flow and/or gas flow (Hornberger and Brady, 1998). Regarding reaction kinetics, the importance of surface area to volume ratios has been described in a previous phase of this study (Brady et al., 2004), and significant differences in crushed particle size distributions and effective surface areas were found among the lithologic units. Standardizing the particle

Jan 1, 2009

By F. Agterberg

In his 1978 monograph ‘Lognormal-de Wijsian Geostatistics for Ore Evaluation’, Professor Danie Krige emphasized the scale-independence of gold and uranium determinations in the Witwatersrand goldfields. It was later established in nonlinear process theory that the original model of de Wijs used by Krige was the earliest example of a multifractal generated by a multiplicative cascade process. Its end product is an assemblage of chemical element concentration values for blocks that are both lognormally distributed and spatially correlated. Variants of de Wijsian geostatistics had already been used by Professor Georges Matheron to explain Krige’s original formula for the relationship between the block variances as well as permanence of frequency distributions for element concentration in blocks of different sizes. Further extensions of this basic approach are concerned with modelling the three-parameter lognormal distribution, the ‘sampling error’, as well as the ‘nugget effect’ and ‘range’ in variogram modelling. This paper is mainly a review of recent multifractal theory, which throws new light on the original findings by Professor Krige on self-similarity of gold and uranium patterns at different scales for blocks of ore by (a) generalizing the original model of de Wijs to account for random cuts; (b) using an accelerated dispersion model to explain the appearance of a third parameter in the lognormal distribution of Witwatersrand gold determinations; and (c) considering that Krige’s sampling error is caused by shape differences between single ore sections and reef areas.

Jan 1, 2015

A wide range of drill holes and process streams are sampled for resource estimation, grade control, and contractual purposes in the minerals industry. However, despite the availability of training courses, conferences and both national and international standards on correct sampling practices, it is still surprising how often little attention is given to ensuring that representative samples are collected for analysis. The reason for this is that the responsibility for sampling is often entrusted to personnel who do not appreciate the significance and importance of sampling, with cost being the main driving force rather than whether the sample is representative of the material from which it was extracted. This seriously undermines the precision and accuracy of the analyses subsequently generated and can render the analysis process a total waste of time and money and expose mining companies to serious, potential, financial losses. Company management needs to reverse this situation and ensure that sampling is given the attention it deserves to generate representative samples for analysis.

Jan 1, 2010

By P. J. Dallimore

The Bureau of Mines has calculated general time-dependent solutions for radon diffusion from cylindrical and slab rock samples containing uniform radium distribution. Results have been obtained for several sets of boundary conditions. The method is suitable for determining the effective diffusion coefficient and the effective porosity for radon.

Jan 1, 1983

By Wayne Anderson

Regarding the technical paper by Thomas E. Finch and Edward L. Fidler, "Recovery of Stray (Thin) Seams in Western Coal Mining." I would like to comment on this subject. In western Canada, most strip mines encounter thin seam coal or rider seams. Although the paper addresses the problems and costs associated with the recovery of this coal, it does not take into account what the savings are. Without looking at the savings, the "Total Objective" is of course not clear. I feel that in a stripping operation the mine can spend per ton (of the thin seam) up to their dragline stripping costs per ton to recover a rider seam or thin seam. The reasoning behind this is simply that this is the price the mine will have to pay to expose an equivalent amount of coal without the recovery of these thin seams. If the mine can recover a rider seam or thin seam for less than the dragline operating costs per ton, a savings will be realized. By recovering a thin seam or rider seam, the life of an ore body is extended by that amount of coal not thrown away. In addition, the cost of land acquisition, associated permits, capital, and reclamation will be reduced as more coal is delivered for a given area. When the above points are considered, the recovery of these thin seams can be very profitable and indeed worth recovering.

Jan 1, 1983

By G. M. Gay, R. L. Perrine

This paper describes a method of numerical computation for three-dimensional, unstable, miscible displacement behavior useful for heterogeneous systems, as well as for more ideal conditions. In the method, flow equations are first linearized by a perturbation approach. The basic flow process is separated and a solution for its behavior readily obtained. The remaining problem of deviations from the basic flow caused by non-ideal conditions is then subjected to numerical analysis. Results obtained from use of the method are also presented. Although conditions assumed in the test cal-culations were severe, results show the type of dispersing flow expected and appear quite satisfactory. The method has eliminated or reduced in importance problems of oscillating values near steep fronts, excessive computer smoothing, etc. A unique advantage of the method is that the source of variations from ideal behavior can be observed. ,The one serious drawback results from the algebraic complexity of the perturbation approach, and the need for second-order terms to be retained in calculations of interest. Fewer array points are available and more computer time is required than would be desired. However, these difficulties are also experienced with other approaches to the solution of three-dimensional dispIacement problems. INTRODUCTION Prediction of behavior of the miscible displacement process within a porous medium for any system of engineering importance is plagued by a number of difficulties. With typical fluid properties the displacing fluid has the lower viscosity, and there is a natural tendency toward flow instability. The problem of predicting instability is compounded by the fact that every real system is heterogeneous. Permeability will vary from point to point — not entirely systematically, and yet not in a random fashion leading to a readily defined average. Furthermore, permeability is unlikely to be isotropic. These permeability properties, which are characteristic of any real porous medium, accentuate the effects of flow instability. Another factor to be considered is that flow dispersion accompanies the displacement process in a porous medium. Mechanistically, dispersion is due to the fact that flow between any two points in the medium follows multiple tortuous paths, each characterized by slightly different flow properties. The fact that the coefficient characterizing dispersive properties of the real medium JS a tensor with variable elements complicates matters. Further difficulties arise because the parabolic influence, while not negligible, is small. Thus, there is a tendency toward steep and uneven displacement fronts along which dispersion smoothing must be represented accurately. Yet frequently used numerical analysis schemes may tend toward either instability, oscillation or excessive smoothing, none of which gives the desired accurate picture of flow behavior. Thus, while many experimental and analytical studies of the process have been made, predictions of actual performance are still subject to considerable uncertainty and possible improvement. This paper reports on part of a study which attempts to develop improved methods for solution of the flow equations describing the miscible displacement process. Of necessity, the calculations were performed on a large digital computer. A three-dimensional system is represented, and the coefficients defining dispersion and permeability can be varied in a manner representative of a real system. Because the differential equations are nonlinear, a first step is to linearize them using a perturbation approach. Objective of this approach has been to separate the basic flow which would occur in an ideal system and for which predictions are readily made. Then the numerical analysis, which is necessarily complex, is directed toward solution of the perturbation equations. These equations state how the basic flow is modified

Jan 1, 1967

By A. F. Raschenko, Y. A. Golodcov, V. V. Elshin

"The autoclave noble metal desorption in apparatuses with a dense stationary sorbent layer is perspective for the technology of sorption gold and silver extraction from solutions and pulps by carbon sorbents. The study of the mechanism and optimization of the autoclave desorption process involve some difficulties. To overcome them it is necessary to use mathematical and quantum-chemical modelling. The given paper deals with a mathematical model for the dynamics of gold and silver desorption from active carbons by alkali solutions based on the physical-chemical notions of the process. The kinetics and the mechanism of the process were investigated using the mathematical model for gold and silver desorption.The calculation of the efficient mass-transfer coefficient (ße) for various initial and intermediate noble metal concentrations in carbon (Cy) made it possible to find that the dependence of ße on Cy in case of gold desoprtion shows a clear extreme character. The value of the initial metal concentration in carbon therewith does not influence the character of the curve the inflection point of which is changed essentially at elevated process temperatures only. The revealed characteristic property, in the author's opinion can only be indicative of the change in the mechanism of gold desorption under autoclave desorption conditions. The assumed [Au(CN)(OH)]- type intermediate that has a higher diffusion coefficient in comparison with the adsorbed complex [Au(CN)2]- can be considered as an intermediate compound in the process of gold desorption."

Jan 1, 2003

By M. P. Tixier, M. Gondouin, G. L. Simard

In the quantitative interpretation of the SP logs, the electrochemical component is generally taken equal to — K log Rm /Rw where K has the theoretical value corresponding to solutions of pure sodium chloride. This method may be misleading when relatively large quantities of salts other than NaCl are present in form-rrtion waters—as is generally the case for low salinities —or in gyp-base muds. In such cases recourse is made in the field to changing the K value or to adding a correction term to the equation on the basis of local experience. An investigation has been made in the laboratory of the influence of HCO3, SO4=, Ca++, and Mg++ on the amplitude of the SP deflection, which included in par-ricular determinations of the activity coefficients of Ca++ and Mg++. The theory, the experimental techniques and a tentative method for applying the results are described. So far, applications to actual field cases where chemical analyses of waters were available have provided an excellent confirmation of the proposed method. The case of the SP in very salty brines is also considered and it is shown that the use of activity data for sodium gives satisfactory results. HISTORICAL In early times of electrical logging, the SP curve was used exclusively as a tool for the location of permeable beds and the definition of their boundaries. Later, with the introduction of methods of quantitative analysis, attention was called to the possibility of deriving from the SP log some information on the formation water resistivity, which constitutes one essential element for the computation of water saturation from log data. The first laboratory experiments' in 1932 had shown that, as a result of electrochemical phenomena arising at the contact of the niud and the formation, the amplitude of the deflection of the SP curve was, at least partly, a function of the salt concentration of interstitial water and accordingly of its resistivity. It was indicated that the amplitude of the electrochemical component of the SP should be equal to K log R1/R2, R1 and R2 being the resistivities of the mud and of the formation water respectively. However, the exact value of the K coefficient was not determined at that time because the surface clay used for a laboratory model was far from an ideal shale membrane. Consequently, the way was not yet open towards quantitative interpretation. In the early forties, Tixier reported2, on the basis of field log observations, the following equation for the case of NaCl solutions, SP = -71 log f1c1/f2c2, c1 and c2 being the concentrations and f1, f2 the mean activity coefficients. The local variations observed in the empirical values of K, chiefly in the Rocky Mountains, led him to advance the opinion that, besides the relative amounts, the nature of the salts present in the solutions had a bearing on the magnitude of the SP. At about the same time Mounce and Rust- ad published laboratory results which emphasized the part played by the shale in the generation of the SP. On the basis of laboratory tests and theoretical considerations, Wyllie in 1948' published the following equation of the electrochemical SP for the case of NaCl solutions, SP= - 71 log (a1)m/(a2)m

Jan 1, 1958

By S. G. Malghan

Steel consumption forms a significant part of the operating cost of a minerals processing plant. An estimated one-quarter billion kilograms of steel in the United States and over one-half billion kilograms in the world are consumed each year in wet grinding alone. The depletion of ore grades and the necessity of finer grinding of abrasive ores are expected to increase the steel consumption even higher. Through continued research and development by the mining industry and the suppliers of steel products several remedies to reduce steel consumption have evolved. This paper critically reviews the mechanisms involved in steel wear, and currently available methods, materials and operating conditions for reducing steel consumption. Particular attention is given to liner design modifications and substitution of steel liners with rubber liners.

Jan 1, 1981

By Dave Stefanuto

Voisey?s Bay Project Components ? Mine/Mill Port In Labrador ? Mini Plant in Mississauga ? Demonstration Plant in Argentia ? Supply Vessel (Umiak1) ? Transshipment Facility (Quebec) ? Concentrate Handling & Transport to Sudbury/Thompson ? Cobalt Refinery Upgrade (Thompson) Project Setting ? The Project is on the traditional lands of the Labrador Inuit and the Labrador Innu ? Canadian courts have held that Aboriginal peoples in Canada possess special rights to traditional Aboriginal lands Those rights can include requiring resource developers to enter into Impacts and Benefits Agreements (IBAs) on traditional lands to set forth how lands can be used and benefits to be received by Aboriginal people

May 1, 2006

By Shawn A. Cefalu, Matthew J. M. Krane, Kent J. VanEvery

"Segregation during electroslag remelting (ESR) of a nickel-chromium-molybdenum alloy (Ni-8 wt% Cr-25 wt% Mo) has been modeled. Features of the model include species transport and AC electromagnetic effects coupled with fluid flow, heat transfer, and solidification. The effect of varying ingot diameter and melt rate, on macrosegregation patterns, local solidification time, and liquid pool profiles obtained from this model are demonstrated. The results show that the macrosegregation in the ingots correlates to the filling velocity.IntroductionElectroslag remelting (ESR) is a secondary melting process used to refine the chemical composition and the microstructure of metals. Macrosegregation of solute elements causes defects in ESR ingots, including freckles and the maldistribution of phases. These defects are not correctable through heat treatment due to the large length scales over which they occur. However, the frequency and distribution of these defects may be minimized, or even prevented, through process control based on an understanding of the conditions that lead to their formation.In the past, studies have been conducted on the effect of the process parameters on the shape of the melt pool and the thickness of the mushy zone [1-7]. In these studies, the shape of the liquid pool is determined by consideration of the heat and fluid flow induced by electromagnetic (Lorentz) force and thermal buoyancy. The transport of solute and the resultant solutal buoyancy effects were not considered in these macroscopic models. Defect formation is tied to formation of secondary phases (e.g., freckling and white spots in nickel superalloys) [5,8]. In cases where secondary phase formation is calculated (e.g., [6]), phase fractions are determined using a micro-scale model given the local solidification time (LST) and local thermal history from the macroscale model.Using the local thermal history from the macroscopic transport model to predict microstructure increases the importance of the accuracy of those results. This investigation models the macrosegregation of molybdenum during the ESR of a Ni-Cr-Mo alloy. The effect of macrosegregation on pool shape and depth is demonstrated, along with its effect on the local solidification time. By comparing the relative effects of the melt rate and ingot radius, a better understanding of the factors that affect macrosegregation, and ultimately secondary phase formation may be obtained."

Jan 1, 2004

By Stephen P. Mulqueen

Searles Lake is an evaporite basin located near the community of Trona in northwestern San Bernardino County, CA. Searles Valley Minerals Operations Inc. (SVM), a subsidiary of Nirma Limited, currently manufactures more than 1.58 Mt/a (1.75 million stpy) of industrial minerals from natural brines produced from several lakebeds within the basin. The chemical manufacturing facilities in Searles Valley represent extremely complex operations involving solution mining and mineral extraction processes.

Jan 1, 2012

By P. M. Robinson, M. B. Bever

The heats oj formation at 273°K of the compounds CdTe, I)z2Te, InTe, In2Te3. In2Te5, SrzTe, and PbTe have been rleasrred in a liquid metal solutiotz caloritrete? 1.t1itlz bismuth as solvent. The?, are iterpretecl in yelation to tlze stability and bonding of the cott/pozltzds. Tile heats of fusion atzd the melting- points of tlze cotlzpounds InTe and Itzz,Te3 1lcti.e been measured in a cotrslant-temperature gradient calorimeter. The entropies of fusion are disc,ztssecl in YIIIS 01. the degree of order in the solid at the melting point. THE heats of formation of the tellurides of cadmium, indium, tin, and lead have been measured as a continuation of research on the thermodynamic properties of compounds of tellurim.' The tellurides of these metals were selected with a view to examining the relation between the heat of formation and the position of the metal in the periodic system. The elements cadmium, indium, and tin are in the same period and tin and lead are in the same group of the periodic system. The tellurides of indium are of special interest because four compounds, In2Te, InTe, In2Te3, and InzTe5, occur in this system. The available information on the heats of formation of the compounds investigated consists of values for CdTe, SnTe, and PbTe derived from electromotive-force measurements,J a value for CdTe obtained by tin solution alorimetr, and values for InTe and In2Te3 determined by combustion calorimetry.5 These values, however, refer to various temperatures ranging from 273' to 673°K and some of the reported error limits are large. Liquid metal solution calorime-try may be expected to yield more accurate values for the heats of formation than electromotive-force measurements or combustion calorimetry. The heats of fusion and the melting points of the compounds InTe and In,Te3 were determined in a constant-temperature gradient calorimeter. No published information appears to be available on the heat of fusion of these compounds. The results reported here give an indication of the degree of order in the solid compounds at the melting point. 1) MATERIALS AND EXPERIMENTAL PROCEDURE Materials. Samples of the compounds SnTe and PbTe were obtained from the Westinghouse Research Laboratories and samples of the compound InTe from Lincoln Laboratory, Massachusetts Institute of Tech- nology. Additional samples of the compounds InTe, SnTe, and PbTe and samples of CdTe, In2Te, In2Te3, and In,Tes were prepared from 99.995 pct Cd (Baker Chemical CO.), 99.999+ pct In (American Smelting and Refining Co.), 99.99 pct Sn (Baker Chemical Co.), 99.999+ pct Pb (Fisher Scientific Co.), and 99.999+ pct Te (American Smelting and Refining Co.). Stoichiometric amounts of the component elements were melted in sealed, evacuated Vycor tubes. The melts were held at approximately 100°C above the liquidus for about 16 hr and shaken repeatedly. The melts of the compounds In2Te and InzTe5, which form by peritectic reactions, were quenched into iced water. The melts of the other compounds, which have congruent melting points, were slowly cooled to room temperature. The samples were then annealed for 5 days at approximately 50°C below their respective solidus temperatures. Metallographic examination did not reveal any evidence of second phases or segregation. At least two batches of each compound were prepared. Samples from each batch were used in determining the heats of formation and, in the cases of InTe and In,Te3, the heats of fusion. The Heats of Formation. The heats of formation at 273°K of the compounds were measured by metal solution calorimetry with liquid bismuth at 623" as solvent. In this technique, the heat of formation is determined from the measured heat effects on dissolution of the compound and of a mechanical mixture of the component elements. The difference between these heat effects adjusted for changes in the composition of the bath gives the heat of formation at the temperature from which the samples are added to the bath (273°K). The experimental technique and method of calculation have been described in detail elsewhere.= It should be emphasized that the reported heats of formation depend on the thermodynamic data used in calculating the heat effects for the calibration additions. In the present investigation, the calorimeter was calibrated by adding pure bismuth at 273°K to the bismuth bath at 623°K. The reported heats of formation are based on a value of 4.96 kcal per g-atom for the difference in the heat contents of bismuth at 623" and 273". If a new value for this quantity becomes available, the reported results may be adjusted in direct proportion. The concentration of solute in the bath at the end of a calorimetric run did not exceed 1.7 at. pct and was usually less. In this range, the heat effect on dissolution of the solute was a linear function of the concentration of solute. In determining the heats of formation of the compounds in the system In-Te, a few runs were carried out in which two neighboring compounds such as InTe and In,Te3 and the corresponding mechanical mixtures of the components were added to the calorimeter. The

Jan 1, 1967

By Jr. Frost

Helium used as a tracer gas in petroleum reservoirs continues to show great promise as a new tool for the oil and gas industry, according to tests conducted jointly by the Bureau of Nines and The Pure Oil Co. in-the Cabin Creek field, Boone and Kanawha Counties, W. Va. Helium, when used as a, tracer gas, is mixed with natural gas being injected into a reservoir for secondary recovery of oil, recycling, pressure-maintenance, or other purposes. Three separate experimental helium tracer-gas tests were run in the Cabin Creek, W. Va., field, wherein helium was added as a tracer to the natural gas that was being injected into the oil-bearing Berea sandstone. The results obtained in each test permitted determining the direction and rate of travel of the injected gas, calculating the volume of injected gas in the gas produced at the various wells, and determining the nature of the transition from natural gas to injected gas during a gas-injection program. Data were obtained on the effects obtained from waves of injected gab containing 1 percent and containing 5 percent helium and from a wave of essentially pure helium injected into the formation.

Jan 1, 1950