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By J. I. Drever, C. R. McKee

The push-pull test, which is a simple injection and pumping sequence of ground water spiked with solutes of interest, is presented as a method of determining the adsorption characteristics of a formation. Adsorption properties are necessary to predict restoration from both in situ coal gasification and in situ uranium extraction. The major problems in applying laboratory measurements to the field concern scaling the effect of particle size, and obtaining representative samples. Laboratory measurements are conducted on gram to kilogram scale samples, whereas the push-pull test evaluates a sample weighing approximately 130 to 1,000 metric tons, depending on volume injected and porosity. The problems in translating laboratory results to the field appear to be less severe for sedimentary uranium bodies than for coal. Laboratory measurements are useful in delineating possible ranges in adsorption properties, and in planning the field experiment. The adsorption properties of a formation are characterized by the cation exchange capacity (C) and the distribution coefficient measured at low concentration, (kd) 'Laboratory procedures for their measurement on coal and uranium ore are reported. Two field push-pull tests were conducted on uranium formations in Wyoming. Adsorption properties estimated from these tests on the basis of a simple cell model were compared to the laboratory values. In the first case, excellent agreement was observed between the values estimated from the field test and the values measured in the laboratory. In the second case, the value for kd determined in the laboratory was 5 times higher than the field value. It is recommended that push-pull tests be conducted on coal formations being considered for in situ gasification in view of the great uncertainty in extrapolating 1aboratory.adsorption properties to the field.

Jan 1, 1979

The paper describes a simulating method.for ground water contamination originating from industrial and mining activrty. The finite difference model simulates heat, mass and solute transport. The applied stochastical method for dispersion provides more accurate solution of mass transport modelling. This method gives a more realistic approach of chemical processes in an aquifer depending on temperature.

Jan 1, 1988

By J. E. Dooley

An analytical procedure developed by the Bureau of Mines was applied to the separation and characterization of a 370° to 535° C distillate from Swan Hills (south field), Alberta, Canada, crude oil. Investigators determined the general characteristics of the crude oil by the Bureau's routine method for crude oil analysis. Suitable fractions were prepared for instrumental analyses by utilizing such techniques as isothermal and molecular distillations, chemical treatment, silica-alumina gel chromatography, and gel permeation chromatography (GK). A detailed characterization of the 370° to 535° C distillate was possible by the application of GPC-mass spectrometry correlations and nuclear magnetic resonance spectrometry. Semiquantitative data based on mass Z series distributions were determined and are shown. The data will be valuable in developing future processing techniques and in calculating yields for converting high-boiling distillates into more useful energy forms.

Jan 1, 1973

By B. J. Dalton

This report gives general expressions for evaluating various thermo-dynamic properties applicable to a two-component system, including liquid-vapor equilibria. In addition, expressions are developed for some of the quantities useful in making thermodynamic consistency checks on phase equilibria data. These formulas were developed from the general principles of thermodynamics and are expressed in terms of the compressibility factor, which is assumed to be an explicit function of the molal density, the absolute thermodynamic temperature, and the composition.

Jan 1, 1968

By Paul Summers, Kevin Richardson, Willem (Billy) Villet, Paul J. Sabatini, Edward C. Clukey

"Between 2008 and 2009, more than 6,000, 23-m long deep mixing method (DMM) elements were constructed to support 124 concrete mats comprising the foundations for the process trains for an LNG facility. The Owner requested first-of-its-kind analyses and assessments to confirm the quality and reliability of the DMM foundation. This paper provides information on these assessments and the procedures used to ultimately conclude that a fit-for-purpose foundation system was constructed.During early phases of construction, several DMM test cores revealed nodules of unmixed clay in upper core samples. A comprehensive review of available DMM core information was undertaken. It was concluded that the amount of coring being conducted as part of the contractor’s QA/QC program should be increased to achieve a foundation system with the required level of reliability.Three-dimensional finite element analyses were completed considering various distributions of defects in the DMM elements and the effects of potential downdrag on DMM elements. Calculated mat settlements and mat stresses were compared to cases without defects in the DMM elements. Various distributions of loaded and unloaded mat areas and number and position (both in the subsurface and laterally) of defects were considered. Four (of the 124) mats were identified as potentially “at-risk”. The settlement performance of these mats is currently being monitored and, to date, performance has been acceptable.IntroductionThe foundation support system for the process train at a major LNG facility comprises more than 6,000, 23-m long DMM elements. The general subsurface stratigraphy at the project site comprises (from the ground surface): (i) up to 8 m of fill sand initially placed underwater building to a stable construction platform; (ii) up to 12 m of soft organic clay (Unit II clay); and (iii) clayey sand and sand layers becoming progressively denser with depth (Unit III sands). Each DMM element comprised two secant 1.5-m diameter DMM columns. DMM elements were typically arranged as cells enclosing one, two, or three DMM elements."

Jan 1, 2017

By E. Poiate, P. R. Cabral, A. V. N. Santos, P. V. M. Costa, C. S. Amaral, A. M. Costa

This paper discusses the design of underground salt caverns, opened by solution mining, for the production of brine and storage of natural gas under high pressures. The caverns are located in the salt basin in Maceio City, Alagoas State, at the northeast region of Brazil. Special attention is given to the geomechanical structural design of the caverns using computer codes specially developed for the simulation of excavations in salt rock formations, considering validated constitutive creep laws under different initial stress states and temperatures. The behavior of sedimentary rocks intercalations presented in the salt layer is simulated using elastic-plastic models. The excavation of the caverns by solution mining is also simulated starting from a geostatic initial equilibrium state of stresses, with a unique formulation only implemented in these computer codes, without the need of the application of boundary stresses to the model in order to develop the initial state of stresses. These computer codes have being used in the design of several clusters of caverns for brine production used as raw material of Poly Vinyl Chloride (PVC) of the Chemical Industryin Brazil. These computer codes and methodology were also applied to the design of the underground conventional potash mine in the state of Sergipe, overlying tachyhydrite and carnallite with very high creep strain rate. They have also been used in the design of the pre-salt oil wells through thick layers of stratified salt rock in Santos Basin, for the exploration and production of the pre-salt reservoirs in Brazil. The constitutive creep equations implemented in the codes are based on a double mechanism creep law. The creep constants adopted in the simulation are taken from a previous investigation carried out on an experimental panel of the potash mine, considering the stratified geology with different salt rocks of the basin where the mine is located. These constants were also obtained by lab tests under different confined and differential stresses and temperatures.

Jan 1, 2015

I do not regard the criticism by Rankin of my work as valid or even meaningful. I strongly reject the assertion by Rankin that my results are invalid. As stated in my paper, the equation to solve (in e. m.u. ) is: [ ] where n2 =4 ps? . This may be rewritten as three scalar equations in Cartesian coordinates, one of which is [ ] The equation to be solved is the diffusion equation, and it is not appropriate to consider waves in this context. In the method a point-wise solution to the problem is approximated. As discussed in my paper the approach taken at discontinuities in conductivity is to choose the normal component of [E] at the discontinuity as the average of the normal components on either side of the discontinuity. This is similar to the well-known assumption made in obtaining Fourier series representations for piecewise continuous functions (Pipes, 1958; p. 51). In the geophysical problem this means that the discontinuity is approximated by a transition zone, which is a very good approximation for such cases. By using this approach, both the values of the function and its derivatives give a good estimate for those associated with the physical situation. It is not apparent and Rankin has not shown that "all the field components and the derivatives are grossly distorted in the region about the boundary" for geophysically realistic situations. He has given no evidence to support his assertation that the results are "invalid". Although Rankin declares that one cannot calculate the electric components from the magnetic, in his discussion he has not stated why this is so. After once calculating the magnetic components the electric components may be calculated, but one must insure that the initial solution is accurate enough to prevent significant round-off errors.

Jan 1, 1973

By G. M. Thain

Ancient Mining - The following three contributions were received for publication in addition to the preceding papers. 1. Ancient gold-mining sites in the Transvaal G. M. THAIN* Pre-European gold mining and working in South Africa is a tantalizing field for conjecture. Well over thousand sites have been identified in Rhodesia, but here we have had to reach double figures, judging by published accounts. Geologically, the Transvaal is less amenable primitive exploitation, but it difficult to reject the idea that the knowledge gained to the north did not have its influence south of the Limpopo.

Jan 1, 1974

By C. Aimone-Martin, C. Dowding, M. Jern, J. Gjødvad

This article compares percentages of compliance for six national standards to demonstrate how these standards vary on-site in a real project. This, to the best of the authors' knowledge, has not been accomplished before. Different standards not only vary in allowable amplitudes of induced vibrations but also in how they are measured (transducer location, transducer orientation, frequency content of vibration, etc.). Thus it is not straightforward to compare the permissible values of induced vibrations with each other. This challenge of comparison is overcome in this project by instrumenting a structure with multiple transducers according to different national standards and comparing the degrees of compliance. Compared herein are compliance with standards used in United States of America, Germany, Great Britain, France, Austria, and Sweden. Averages of the percentage of compliance and ratios of measured vibration amplitudes for all six national standards are compared both in tabular and graphical form for 20 blasts at the Aitik mine northern Sweden. It is the largest open pit mine in Europe and blasts are atypically large with more than 1000 kg charge per hole and several hundred holes per blast, lasting 3-5 seconds. Results show that percentages of compliance can vary by as much as 2 to 75 % for these blasts at this structure. The overall project is a cooperative effort between EFEE (European Federation of Explosives Engineers) and ISEE (International Society of Explosives Engineers), supported by more than 17 persons from 8 different countries. At the present the experts are the four authors of the present paper and Dr. Robert Farenfield, Dr. Nathan Rouse, Douglas Rudenko, Brent Meins, Kenneth K. Eltschlager, Karin NorénCosgriff, Travis A. Davidsavor, Vitor Luconi Rosenhaim, Johannes Kutschera, Bernard Thierry, Thomas Moser, Cory Loukedis, and Keith Best. The project began with a literature study and a survey including an evaluation of the answers provided by members of EFEE. Results were presented at the ISEE conference in Denver 2020 as well as the EFEE conference in Helsinki in 2019 (Gjødvad & Jern, 2019; 2020). The second part of the project was initiated in May 2021 with installation of 7 seismographs from two different manufactures, 3 cracs gauges and 2 microphones on a building at the Aitik mine in northern Sweden. The third part of the project has moved to the United States. Two residential structures adjacent to quarries are being monitored in Michigan and Ohio. Installation and monitoring began in March 2023 and are expected to continue for 6 to 12 months. In addition to the objectives of phase two the 2023 study includes calculations of global wall strains from measured velocity time histories and measurement of response of existing cracks to vibratory and climatological effects

Jan 1, 2024

By George P. Demopoulos, Vladimiros G. Papangelakis, Dimitrios Filippou, A. J. Monhemius, G. W. Warren, E. Peters

A new method developed for the estimation of the activity of Ht in mixed sulfate solutions is described and examples of application of this method to the system H2SO4-ZnSO4-FeSO4-Fe2(SO4)3 from 298 to 473 K are offered. The method makes use of an "extended Debye-Hiickel" type of equation that was originally put forth by Das for pure H2SO4 solutions at ambient temperature. The treatment of mixed sulfate solutions was made possible by combining that equation of Das with a speciation algorithm which calculates the abundance of all species formed. The developed method, which also takes into account ionic strength and temperature effects, was used to generate hydrogen ion activity and speciation data for all possible acid/metal sulfate pairs of the system H2SO4-ZnSO4-FeSO4-Fe2(SO4)3. Finally, under the light of the reported data, specific examples of hydrometallurgical reaction systems are analyzed in terms of thermodynamics or kinetics. In particular, the systems discussed are: hydrometallurgical precipitation of hematite, solvent extraction of Fe(III), acid leaching of zinc ferrite, and oxidation of Fe(II) to Fe(III) by O2(aq).

Jan 1, 1993

By Forrest T. Moyer, J. I. DAVIS, JOSEPH H. SCHUSTER, E. K. ELSNER

The National Safety Competition conducted by the Bureau of Mines, United States Department of the Interior, is held each year for the purpose of promoting safety in the mineral industries of the United States. Since the program was inaugurated in 1925, twenty-three safety competitions have been held. This publication is a report of the results of the contests held in 1944, 1945, 1946, and 1947. The names of plants that have been awarded "Sentinels of Safety" trophies and Certificates of Achievement in Safety dur- ing these years, together with a summary of their achievements in injury prevention, are listed. Statistical data covering the injury experience of all plants entered in the annual contests also are included in this publi- cation. The injury statistics of these plants, arranged in the six groups of the competition, are the only data on injury severity at mineral operations available to the Bureau of Mines. Interest in the National Safety Competition has increased steadily. The number of participating plants has increased from 210 in 1925, the first year of the competition, to the record number of 494 in 1946. The widening scope of the competition means that a steadily increasing number of the mines and quarries in the United States are participating in a program that will supplement their other activities in promoting safety. Safety competitions have long been recognized as instrumental in stimulating and holding the interest of employees and officials in accident-prevention work. During the years covered by this report, conditions in the mineral industries of the United States were hardly conducive to setting records in accident prevention. During the war years, handicaps were especially severe- loss of skilled employees to the armed forces or to higher-wage war industries, greater production by a smaller force of workers, relatively high rates of labor turn-over, the longer workday in effect through 1944 and 1945, and difficulties in obtaining repairs and replacement for badly worn machinery. Even the immediate postwar period has brought no abatement of the tremendous pressure upon the mineral industries for greater production. Although there was a decrease of 18 in 1947 from the record enrollment in 1946, these oper- ations worked 160,525,025 man-hours, the greatest number of man-hours of exposure to mining hazards in any year of the contest except 1942. Despite the accelerated pace at which the mineral industry worked during the 4 years covered by this report, participants in the National Safety Competition have achieved creditable performances in the promotion of safety. In fact, the injury-severity rate in the enrolled plants in the 1947 contest was 7.315 days for each thousand man-hours worked, the lowest by far in the history of the National Safety Competition. The injury-frequency rate of 42.155 for each million man-hours of exposure to mine hazards in 1947 marks a favorable trend downward from the rate of 50.577 in 1946, which was the

Dec 1, 1949

By G. Potts, K. Raiber, T. BoBo

Effective control of balling line circuits is a problem taconite companies have been dealing with for over thirty years. The sensitivity of balling circuits to changes in moisture, bentonite, concentrate particle size, and other operating parameters are the main reasons for control problems. This paper presents test results and describes the integration of existing instrumentation with a digital image analysis system on a balling circuit. This work has the goal of developing control strategies to automatically adjust water spray and bentonite addition, to optimize the size distribution on the roll screen and reduce the variability in control between balling attendants, resulting in more consistent greenball product quality.

Jan 1, 2003

By Giorgio De Tomi, Ricardo Tichauer

Mineral exploration is a critical step for success in mining. However, small-scale mining often ignores exploration best practices. This paper introduces the Tichauer-DeTomi Matrix, a tool for assessment of geological uncertainty in small-scale mining. This matrix, which measures the level of compliance of exploration programs in small deposits with industry best practices, has been applied to three small mining projects in Brazil: an artisanal gold mine in the Amazon, a small-scale manganese mining venture in the Northeast, and a small manganese deposit in the Southeast. The application of the matrix resulted in indexes that reflect the actual level of maturity of the mineral exploration program in each project. Therefore, the matrix has shown potential to be an effective tool for assessment of the geological uncertainty remaining in small-scale mineral projects, as well as to identify priority exploration activities for reduction of risks associated with the geological uncertainty. As a risk assessment tool, the TichauerDeTomi Matrix may be helpful in promoting investment and sustained development in and around small mines.

By V. L. Elliott, C. L. Meyette

The conditioning of semifinished steel products such as billets, blooms, and slabs to remove surface defects before further processing to finished products is a necessary accompaniment to steel mill rolling operations. A knowledge of the kinds of defects which occur and of the conditions in melting, teeming, and rolling that may lead to their occurrence is favorable to the production of quality products. Surface defects may be classed as either of mechanical origin such as those that occur in the heating and rolling operations and include breaks, tears, guide marks, mechanical laps and the like, or they may have been in the ingot before heating and rolling. Examples of the latter are ingot cracks, blow-holes, scabs, and inclusions which lead to the numerous known types of seams and surface flaws. Most of the common types of surface defects and methods for their identification by visual examination or by the aid of macro-etch tests are well known. The conditions which caused their formation are also appreciably understood and this knowledge has been instrumental in the establishment of methods for metallurgical control. There are, however, defects of doubtful origin. In any endeavor to trace the causes for their occurrence, the question of first concern is: I. Whether they were formed in the rolling procedure. 2. Whether they existed in the ingot prior to rolling. In the case of semifinished products which are rerolled to finished products there is also the question of whether they were formed in the primary or in the secondary rolling. In metallurgical laboratories where numerous or routine examinations of the quality of rolled products are made over the course of time, there will doubtless be many puzzling cases of defect origin. Microscopic examination of the defects may, however, reveal a characterizing condition that can be used to classify them broadly with respect to their origin. Such a condition has been observed and, after detailed investigation, is described here with the thought that it may offer a usable and relatively simple solution to a bothersome problem. Basis For Classifying In this discussion the term "mechanical type defects" will be used to designate those that have occurred as a result of the rolling operations such as in rolling from the ingot to billets, blooms, or slabs or in rerolling to finished products. The term "steel type defects" will be used to designate those that were present in the ingot prior to primary rolling or that were in the semifinished product prior to secondary rolling to finished product. The basis for distinguishing between the two types of defects lies in the relative degree of subscale formation surrounding them. Subscale is defined1 as a zone of

Jan 1, 1949

By V. L. Elliott, C. L. Meyette

The conditioning of semifinished steel products such as billets, blooms, and slabs to remove surface defects before further processing to finished products is a necessary accompaniment to steel mill rolling operations. A knowledge of the kinds of defects which occur and of the conditions in melting, teeming, and rolling that may lead to their occurrence is favorable to the production of quality products. Surface defects may be classed as either of mechanical origin such as those that occur in the heating and rolling operations and include breaks, tears, guide marks, mechanical laps and the like, or they may have been in the ingot before heating and rolling. Examples of the latter are ingot cracks, blow-holes, scabs, and inclusions which lead to the numerous known types of seams and surface flaws. Most of the common types of surface defects and methods for their identification by visual examination or by the aid of macro-etch tests are well known. The conditions which caused their formation are also appreciably understood and this knowledge has been instrumental in the establishment of methods for metallurgical control. There are, however, defects of doubtful origin. In any endeavor to trace the causes for their occurrence, the question of first concern is: I. Whether they were formed in the rolling procedure. 2. Whether they existed in the ingot prior to rolling. In the case of semifinished products which are rerolled to finished products there is also the question of whether they were formed in the primary or in the secondary rolling. In metallurgical laboratories where numerous or routine examinations of the quality of rolled products are made over the course of time, there will doubtless be many puzzling cases of defect origin. Microscopic examination of the defects may, however, reveal a characterizing condition that can be used to classify them broadly with respect to their origin. Such a condition has been observed and, after detailed investigation, is described here with the thought that it may offer a usable and relatively simple solution to a bothersome problem. Basis For Classifying In this discussion the term "mechanical type defects" will be used to designate those that have occurred as a result of the rolling operations such as in rolling from the ingot to billets, blooms, or slabs or in rerolling to finished products. The term "steel type defects" will be used to designate those that were present in the ingot prior to primary rolling or that were in the semifinished product prior to secondary rolling to finished product. The basis for distinguishing between the two types of defects lies in the relative degree of subscale formation surrounding them. Subscale is defined1 as a zone of

Jan 1, 1949

By Heric Henrique Souza e Silva, Johne Jesus Mol Peixoto, Natalia Barros Barony, Itavahn Alves da Silva, Weslei Viana Gabriel, Carlos Antonio da Silva, Varadarajan Seshadri

In this work the circulation rates have been determined in a 1:7.5 scale physical model of RH reactor (Ruhrstal Heraeus) and using oil/water and oil/zinc chloride solution to simulate steel melt/slag in the prototype with the objective of evaluating the influence of density and viscosity on the entrainment of oil simulating slag. A technique based on strain gage bridge and particle image velocimetry was developed to assess the circulation rate, as the usual tracer method is not feasible due to the presence of chloride ions in ZnCl2. The critical velocity and critical diameter of oil drops for slag (oil) entrainment in water/oil and ZnCl2/oil systems were estimated using equations from the literature. Due to the difference in density, the ZnCl2/oil system, showed a critical velocity that is 28% higher than the silicone oil/water system while the maximum size of the entrained droplets was about 65% lower than that for water/oil system.

Mar 1, 2017

By S. A. H Tyrrell, R. Rotzinger

"Taseko Mines Limited recommenced operation of the Gibraltar copper-molybdenum mine in 2004 and embarked on series of development projects to modernize the mine and increase throughput capacity. The Gibraltar Development Plan 3 (GDP3) project included a second stand-alone copper-molybdenum concentrator, a stand-alone molybdenum separation plant and associated services. Ausenco was contracted to commence the detailed design in 2Q2011, commissioning commenced in 4Q2012 and first ore was processed in 1Q2013. This paper discusses the design, implementation and commissioning of the GDP3 Concentrator.INTRODUCTION The Gibraltar Mine (Gibraltar) property is located in the Cariboo Region of south central British Columbia, approximately 360 kilometers northeast of Vancouver. The site is accessed via an 18 kilometer paved road from the town of McLeese Lake, which is located on the province’s main north-south highway between the cities of Williams Lake and Quesnel. Gibraltar was originally developed by Placer Development and commenced production in 1972. Gibraltar was acquired, while on care and maintenance, by Taseko Mines Limited (Taseko) in 1999 during a period of unusually low metal prices. Taseko recommenced operations at Gibraltar in 2004, and embarked on series of development projects to modernize the mine and increase throughput capacity. The 1972 Gibraltar process flowsheet incorporated two-stage crushing followed by rod and ball milling and flotation. In 2008 Gibraltar completed their first development stage that included the installation of a SAG mill, converting the existing rod mills to ball mills and adding additional flotation capacity. Gibraltar continued development with the installation of an in-pit primary crusher, expansion of the bulk regrind circuit, expansion of the cleaner flotation circuit, replacement of the tailings pumping system and replacement of the concentrate filters and dryer."

Jan 1, 2014

By E. A. Nesbitt

A new permanent-magnet material has been developed with unusual mechanical as well as magnetic properties. Specimens that have been cast or subjected to a small amount of hot reduction by rolling or swaging may be machined, punched, tapped or drilled. The composition range of the alloys is 30 to 52 per cent iron, 36 to 62 per cent cobalt and 4 to 16 per cent vanadium. After being either quenched, annealed or given the usual cold finishing passes and then heated for 2 hr. at 600°C., such materials have a magnetic energy product of 1.0 X 106 gauss-oersteds. This product is equivalent to that of the well-known Honda steel (36 per cent Co, 4W, 2 Cr, 0.8 C. 0.3 Mn, balance Fe). Material handled in the manner just described does not depend on cold-working for its magnetic properties, and is known as Vicalloy I. The preferred composition for Vicalloy I is 38.5 per cent iron, 52 per cent cobalt and 9.5 per cent vanadium. When the alloys are first hot-worked, then considerably reduced in area by cold-swaging, drawing or groove rolling and then heat-treated, the magnetic energy product measured in the direction of previous extension is increased to 2.0 to 3.5 X 106 gauss-oersteds. These higher values have been obtained only after cold reductions in area of 75 to 95 per cent. Material handled in this manner is known as Vicalloy II and the preferred composi-

Jan 1, 1947

By E. A. Nesbitt

A new permanent-magnet material has been developed with unusual mechanical as well as magnetic properties. Specimens that have been cast or subjected to a small amount of hot reduction by rolling or swaging may be machined, punched, tapped or drilled. The composition range of the alloys is 30 to 52 per cent iron, 36 to 62 per cent cobalt and 4 to 16 per cent vanadium. After being either quenched, annealed or given the usual cold finishing passes and then heated for 2 hr. at 600°C., such materials have a magnetic energy product of 1.0 X 106 gauss-oersteds. This product is equivalent to that of the well-known Honda steel (36 per cent Co, 4W, 2 Cr, 0.8 C. 0.3 Mn, balance Fe). Material handled in the manner just described does not depend on cold-working for its magnetic properties, and is known as Vicalloy I. The preferred composition for Vicalloy I is 38.5 per cent iron, 52 per cent cobalt and 9.5 per cent vanadium. When the alloys are first hot-worked, then considerably reduced in area by cold-swaging, drawing or groove rolling and then heat-treated, the magnetic energy product measured in the direction of previous extension is increased to 2.0 to 3.5 X 106 gauss-oersteds. These higher values have been obtained only after cold reductions in area of 75 to 95 per cent. Material handled in this manner is known as Vicalloy II and the preferred composi-

Jan 1, 1947

By H. C. Fiedler

SILICON-IRON strip with a cube-on-edge secondary recrystallization texture is made commercially as thin as 10 mils. With inclusions present to inhibit normal grain growth, a few grains, and these have the (110)[001] orientation, grow very large at the expense of the matrix grains. In the absence of inclusions, only normal grain growth occurs and the texture is not as strong as when it is developed by secondary recrystallization.1 Strip for use at frequencies of 400 cps and higher is made in thicknesses of 1, 2, and 4 mils by a process developed by Littmann.2 Attempts to develop a strong texture in these thin gages by the same methods as were used for the 10 mil and thicker strip were unsuccessful,2 and Littmann's solution to this problem was to cold roll the grain

Jan 1, 1963