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By K. O. Stamm, B. A. Rogers

Because it is the basis of the economically important operation of hardening steel by quenching, the A3 transformation in iron has been the subject of numerous investigations. Although the contributions to this subject are interesting, no general review will be given here. Readers who care to follow the matter further are referred to the comprehensive summary by Cleaves and Thompson,l which covers the literature to about 1935. Their references to 53 papers on the subject suggest that further investigation is hardly justifiable. However, considerable interest has devel oped recently concerning the reversibility of the transformation. From thermo-dynamic considerations, the transition ought to occur at the same point on heating or cooling, if the change of temperature is sufficiently slow. Yet all of the earlier investigators found a difference of several degrees. Burgess and Crowe,2 who used thermal methods, obtained average temperatures of 912" for Ac3 and 900°C. for Ar3 on electrolytic iron. Their data indicate a considerable range of temperature over which the change occurs, both on heating and on cooling. Terry3 measured the susceptibility in the critical range and estimated from the steepest parts of his curves that Ac3 came at 9I8° and Ar3 at 903°C. Ishiwara4 was one of the first investigators to report a shorter interval between the temperature of the change in the two directions. He measured the change of susceptibility of kaolin-coated samples of steel, in a hydrogen atmosphere, at rater of heating and cooling so low that about 3 or 4 hr. were required for the transformation to complete itself. His results show some variability between samples, but indicate that the difference between Ac3 and Ar3 is in the vicinity of 6°C. Roberts and Davey5 measured the space lattice in pure iron in the vicinity of 900°C. and concluded that a change occurs reversibly between 907' 3" and 910" 3°C., probably between 907" and 910°C. Wells, Ackley, and Meh16 made dilatometric determinations of the Ac3 and Ar3 points in samples of hydrogen-treated carbonyl iron maintained under a vacuum. They used three rates of heating and cooling: 2°, ½°, and .?°C. per min. and found the spread between the two points decreased with low rates. At the slowest rate, the Ac3 transition occurred at 909° to 909. 5°C. and the Ar3 change at 907°C. in three of the samples believed to contain the lowest percentages of alien elements. They concluded that if the rate of temperature change and the content of alien eiements were low enough, the A3 transformation would be completely reversible at 909.50 + 1°C. The question of reversibility is an interesting one and when some iron with especially small percentages of alien elements became available the opportunity to conduct an investigation was welcomed. This iron was prepared by the Division of

Jan 1, 1942

By B. A. Rogers, K. O. Stamm

Because it is the basis of the economically important operation of hardening steel by quenching, the A3 transformation in iron has been the subject of numerous investigations. Although the contributions to this subject are interesting, no general review will be given here. Readers who care to follow the matter further are referred to the comprehensive summary by Cleaves and Thompson,l which covers the literature to about 1935. Their references to 53 papers on the subject suggest that further investigation is hardly justifiable. However, considerable interest has devel oped recently concerning the reversibility of the transformation. From thermo-dynamic considerations, the transition ought to occur at the same point on heating or cooling, if the change of temperature is sufficiently slow. Yet all of the earlier investigators found a difference of several degrees. Burgess and Crowe,2 who used thermal methods, obtained average temperatures of 912" for Ac3 and 900°C. for Ar3 on electrolytic iron. Their data indicate a considerable range of temperature over which the change occurs, both on heating and on cooling. Terry3 measured the susceptibility in the critical range and estimated from the steepest parts of his curves that Ac3 came at 9I8° and Ar3 at 903°C. Ishiwara4 was one of the first investigators to report a shorter interval between the temperature of the change in the two directions. He measured the change of susceptibility of kaolin-coated samples of steel, in a hydrogen atmosphere, at rater of heating and cooling so low that about 3 or 4 hr. were required for the transformation to complete itself. His results show some variability between samples, but indicate that the difference between Ac3 and Ar3 is in the vicinity of 6°C. Roberts and Davey5 measured the space lattice in pure iron in the vicinity of 900°C. and concluded that a change occurs reversibly between 907' 3" and 910" 3°C., probably between 907" and 910°C. Wells, Ackley, and Meh16 made dilatometric determinations of the Ac3 and Ar3 points in samples of hydrogen-treated carbonyl iron maintained under a vacuum. They used three rates of heating and cooling: 2°, ½°, and .?°C. per min. and found the spread between the two points decreased with low rates. At the slowest rate, the Ac3 transition occurred at 909° to 909. 5°C. and the Ar3 change at 907°C. in three of the samples believed to contain the lowest percentages of alien elements. They concluded that if the rate of temperature change and the content of alien eiements were low enough, the A3 transformation would be completely reversible at 909.50 + 1°C. The question of reversibility is an interesting one and when some iron with especially small percentages of alien elements became available the opportunity to conduct an investigation was welcomed. This iron was prepared by the Division of

Jan 1, 1942

By Robert McIvor

The following is a summary of the Robert H. Richards Lecture on “Learning and Good Fortune on the Road to Discovery” presented at the Mineral & Metallurgical Processing Division (MPD) Awards Plenary Session on Feb. 23, 2026 during the MINEXCHANGE 2026 SME Annual Conference & Expo in Salt Lake City, UT.

Mar 1, 2026

Mining is big business in Ontario. The province is Canada?s leading mining region. It consistently ranks among the top 10 jurisdictions worldwide for exploration spending, reaching about C$1 billion in 2011. More than 26 percent of all exploration and appraisal dollars spent in Canada are invested in Ontario. Minerals produced include nickel, copper, platinum group elements (PGE), cobalt, zinc, diamonds, gold and silver. It was reported that there are more than 600 mining exploration projects in the province. And, recent discoveries of chromite in northern Ontario?s Ring of Fire will add to the province?s mineral production in the coming years.

Jan 1, 2013

By Tom Learmont

The importance of coal in solving our energy problems has been widely discussed; the world demand for food requires increased fertilizer production and the minerals to produce fertilizer must be mined. We have seen an explosive increase in the demand for large stripping equipment. It is appropriate that we review this equipment and determine what can be done to improve productivity. While we have used coal mining as an example in the study, much of the discussion will apply equally to other forms of stripping.

Jan 1, 1975

By D. B. RUSHJIORE

(New York -Meeting, February, 1912.) TORCHES were used by the early Romans for mine-lighting, and these were followed by open lamps or earthen jars filled with tallow or oil, and later by candles. In early coal-mining, explosive gases seldom occurred, and, if they were encountered, the danger of explosion was materially diminished by the absence of any ventilating-system and the consequent insufficient circulation of air to form with the methane an explosive mixture. As the art advanced, the danger of fire-damp became more apparent, and methods for testing the air were resorted to as early as in the fifteenth century. The method of testing consisted in lowering a clog in a, basket down the shaft. As soon as he encountered fire-damp he would commence to howl, after which he was withdrawn, and a leafy bush was fastened to the end of the rope and run rapidly up and clown the shaft. This so disturbed the accumulation of gas as to cause it to rise out of the shaft. Later this odd method of testing was improved upon through the discovery that a light inserted in a body of fire-dam p would produce a blue flame. Candles were used for this purpose, and, when fire-damp was thus discovered, brushing or some other primitive method of fanning was resorted to for driving out the gas. In some instances the gas was burned away, regardless of the danger thereby incurred. A man, wearing a well-moistened coat and a mask with glass spectacles, descended in the mine a few hours before each shift. With a long stick, to which was fastened a burning torch or candle, lie would crawl on the floor with the stick so raised that the light would sweep the roof and ignite the gas which it encountered. In this position the flame of the explosion would pass over him, after which he would retreat from the gases resulting from the combustion. The occurrence of serious accidents resulted in

Jul 1, 1912

By W. G. K. Fleming

The general history of piling is traced up to the present time with regard to the evolution of methods and materials. The processes have been strongly influenced by developments in basic equipment and industrial change. It is noticeable that in the twentieth century more progress has taken place than in the many previous centuries. It has been strongly influenced by the general development of Soil Mechanics. Test loading is probably the most effective way to assess the success of designs and many empirical relationships have been challenged through it. As we approach a new century it appears that it will be an age of rapid equipment development, with much enhancement of understanding of what has been done. Processes of automatic construction and testing will becoming commonplace. These changes will narrow the limits of conventional scatter that have come to be accepted and to a large extent will be driven by political efforts to curtail energy consumption, to raise standards of quality and reliability, and to conserve the environment. 1. Ancient history. Piling is an ancient art. Its first mention in history is from Herodotus, the first person to commit an account of his times to the written word in the years 557 to 479 BC. He evidently had a strong interest in engineering matters because he wrote of building, brick making, reinforced brickwork, river training, canal building, bridge construction, tunnelling and its acoustic detection and piling. The piling reference comes from Book 5 at paragraph 16.

Jan 1, 1999

By Nasri Munfah, Raymond E. Sandiford

"Superstorm Sandy (Sandy) created a storm surge that inundating many of the tunnels that pass beneath the Hudson and East Rivers. The tunnels are vital infrastructure links for the economy of New York City and the northeast region. The sea water, which contains highly reactive salts, caused significant damage to electrical and mechanical systems. In addition, the salt water inundation left corrosive precipitants on the tunnel linings and on and within electrical duck banks. After the salt water was evacuated from the tunnels, condition assessments were performed using a state of the art approach involving high resolution laser scanning, digital imaging, and thermal imaging. These scans were performed prior to hands on inspections. The damage assessment concluded that, although the tunnel structural linings were not damaged, the interior elements of the tunnels needed major rehabilitation to arrest the continual deterioration of the structures. This paper details the state of the art approach used for these tunnel inspections. INTRODUCTION On October 29, 2012 Super Storm Sandy flooded a large number of both transit and vehicular tunnels in the New York Metropolitan area. The region’s transportation network was severely disrupted. The storm damage is estimated to have been in excess of $30 billion, and with the tunnels out of service, the local economy was losing hundreds of millions in economic activity. Restoration of these tunnels was a very high priority and the resulting expedited restoration process did not always provide adequate time for comprehensive condition surveys. This resulted in many of these surveys being conducted after service restoration. Inspecting highly trafficked transit tunnels is challenging and the logistics of working in short night outages led to a rethinking of the conventional inspection approach. Traditionally, visual and tactile methods are first used to inspect tunnels and then quite often followed by LiDAR (Light Detection and Ranging) scanning and perhaps infra-red scanning. For multi-mile tunnels, the time required to visually map tunnel features can be quite extensive. By performing the scanning first and then performing the visual and tactile inspections, one is able to use the scan data to identify the specific areas that need detailed inspections. This approach was used quite successfully for a number of the NYC tunnels."

Jan 1, 2016

By Andrew Allan

[This report describe the first experiment of the Anthracite Research Laboratory, Bureau of Miners, in attempting to reduce underground-mining costs and conserve anthracite as a natural r-source by introducing now minim methods. The work war, dons in cooperation with one of the large anthracite-producing companies. It applies to productive mining, characterized by comparatively low cost, per ton and high production per man, as differentiated from development mining, which is always necessary before the, productive or retreat phase can begin. The system d scribed in this report is believed to be generally applicable to beds pitching 70° to 90° and, under certain conditions, to beds pitching loss than 70°. After development hate been completed, an openings is made, extending the full width of the 9- to 10-foot coal bad and reaching from the haulageway to the vertical limits of the solid coal. Long drill holes (20 to 50 feet) charged with about one stick of permissible explosive riper foot of length are fused to break the coal. Once broken, the coal is loaded onto a shaker conveyor by gravity and thence into mine: cars. The coal is mined retreating in 15- to 20-foot sections that are broken and loaded onto the conveyor through a specially constructed chute. In the Bureau?s experimental work, the height of sections arse ranged from 35 to 60 fact, depending on the geologic extent of the coal bed.]

Jan 1, 1952

By Edward P. Larsen

At our annual meeting in St, Louis, Mo. in February 1961, we presented a comprehensive paper (No. 61-B-22) on the subject of "Blending and Handling of Materials for Agglomeration". In that paper you will find a discussion on the difference between "blending" and "mixing". With regard to "blending" we brought out the facts of its usefulness for the preparation o materials in an agglomerated mass to attain controlled chemical and physical uniformity. "Mixing" was discredited as not being useful for the attainment of uniformity of any kind.

Jan 1, 1962

By R. J. Smith

Tar sand deposits in Utah represent more than 25 billion barrels of in-place bitumen, 96% of the known U.S. reserves. The technological development of a hot water processing strategy for the Canadian tar sands and the commercial Production of synthetic crude oil from this natural resource suggest that similar success may be possible for the utilization of Utah tar sands to provide our country with a new domestic source of synthetic crude oil. In this regard an active research program to develop a hot water processing strategy for Utah tar sands has been sustained at the University of Utah for the past five years. The hot water process for Utah tar sands differs significantly from that used for Canadian, tar sands due to the inherent differences in the respective bitumen viscosities and the nature of the bitumen-sand association. These differences have led to the identification of certain design criteria necessary to achieve satisfactory phase disengagement during digestion. (8,9) Subsequent flotation of the digested tar sand is a subject of current attention and is considered in this contribution for the Asphalt Ridge tar sand deposit. Although contact angle measurements of pure Asphalt Ridge bitumen indicate moderate hydrophobicity, air bubble attachment to the bitumen concentrate taken from a 37 liter flotation cell is not possible. This surprising result suggests that the flotation separation is dependent on air bubble entrapment rather than on attachment due to surface hydrophobicity. The occlusion of air bubbles in the bitumen is apparent from visual examination of the concentrate, especially at lower temperatures. It seems that a bitumen bubble agglomerate forms in the impeller region of the flotation cell, the effective density of which is such to allow the agglomerate to float to the surface. A factorial design of the major operating variables in the flotation separation indicated that the quality of separation was significantly dependent on the flotation temperature and to a lesser extent on the degree of agitation. For a flotation temperature of 77C recovery of 96.7 percent was realized at a grade of 61.0 percent bitumen. The improved separation at higher flotation temperatures was found to be due to the decrease in bitumen viscosity resulting in more effective rejection of coarse sand from the concentrate.

Jan 1, 1980

By J. Mullins

Coal was first banked by the Dominion Coal Company, Limited, in 1898, near No. 2 Colliery, the same site as is presently used for that purpose. Though today there are banks at Glace Bay, Sydney, and Sydney Mines, these notes, except when otherwise desirable, will be confined to describing the practice as developed at the No. 2 Banking Station, Glace Bay, as being typical of methods obtaining at all sites. Storing The manner in which the coal was piled is illustrated diagrammatically in the accompanying sketch. A train of coal was brought on the main trestle, which extended the full length of the banking ground at a height of 22 to 39 feet above the natural surface, and dumped into bins which were integral with the trestle work. Chutes from these bins permitted the coal to be fed into 3-ton cars, which were horse drawn laterally on narrow gauge tracks laid about 10 ft. centres, to a maximum distance of 400ft. from the trestle. These cars were end-dump and as the pile extended laterally the narrow gauge tracks were lengthened by shorter or longer filling pieces, so that their ends were always kept at the brow of the bank. Much coal, however, had to be dumped directly on the tracks and hand trimmed to fill the valleys, and level off, between the tracks.

Jan 1, 1931

By William H. White

"AbstractThe value of anomalous metal contents of trees as an aid to the discovery of mineral deposits was tested under field conditions cm four known ore deposits. Results indicate that a base-metal deposit, or any deposit containing zinc or copper, casts a 'metal shadow' into the overlying soil which remains approximately positioned above the deposit, regardless of the type of overburden or the movement of groundwater.The unusually high content of zinc or copper in trees growing within the limits of this 'metal shadow' constitutes an anomaly which can be detected and ,plotted in the field The field kit and certain points of the field technique are described briefly; and the characteristics of plant anomalies and possible limitations of their use are mentioned.IntroductionRecent investigations concerning the metal content of trees indicate not only wide variations in the metal content of different species and in different parts of the same tree but, in addition, suggest that the metal content of a tree is related to that of the subjacent bed-rock. Abnormal values found by Warren, Delavault, and others in trees growing above or near orebodies suggest a new tool which may prove of considerable value in exploration work. Evaluation of this new tool must involve consideration of the following questions:(I) Is the technique one which can be used under field conditions by persons not specially trained; and can results be duplicated within reasonable limits of error? Rather than taking tree samples for subsequent laboratory analysis, it is highly desirable that analyses be made on the spot. This allows anomalous results to be checked and additional samples may be taken at key points."

Jan 1, 1950

By C. Gosselin, M. Rheault, M. Benoit, Y. Bouroubi, V. Sarago

The last three decades have seen significant mining development in northern regions of Canada, where the freeze and thaw cycle of permafrost and the corresponding surface subsidence and heave represent a significant challenge to the design and maintenance of infrastructures. Identifying areas at risk is of great assistance to reduce the impact of this issue. Over the past ten years, Synthetic Aperture Radar Interferometry (InSAR) has been widely used to monitor ground surface deformation. With this technique, changes in phase between two SAR acquisitions are used to detect centimeter to millimeter surface displacements over a large area and with high spatial resolution. InSAR can be used as a tool to assist the siting and design of new infrastructure as well as highlighting the risk to existing structures in areas of unstable terrain. This paper presents the results of a project carried out by Effigis, which made use of SAR interferometry in the context of monitoring terrain and infrastructure stability in a northern mining environment that is affected by permafrost seasonal and long term changes. TerraSAR-X images acquired during two periods, August to November 2012 and March to October 2013, were used to measure the deformations and/or movement of ground surface, infrastructure and stockpiles caused by seasonal changes in permafrost extent in and around a mining site located in Nunavik, Quebec. The results showed that spatial and temporal distributions of surface displacements are in accordance with scientific and terrain knowledge. Some displacements were observed in loose soil areas while, as expected, none were detected in bedrock and rock outcrop areas. The areas most affected by active layer changes showed surface subsidence in the thaw settlement period. This study confirms that SAR interferometry has a great potential for operational applications related to risks induced by surface deformation in mining environments. It shows that this technique can be used to produce reliable maps of surface movement and monitor the vertical displacement of important infrastructure.

Jan 1, 2015

By J. A. Folinsbee, Andre Robitaille, Tony Y. Chong

"Conventional crushing and grinding is followed by gravity concentration to recover free milling gold. Refractory gold, finely disseminated within the pyrite and arsenopyrite matrix, is recovered by flotation followed by pressure oxidation, cyanidation, and cementation. Non-refractory gold is recovered by cyanidation/CIP processing.A comprehensive test program aimed at improving flotation recovery was initiated in June 1995. Plant testing indicated that flotation tails value could be significantly reduced using mechanical flotation cells. Based on these test results, a flotation circuit that incorporates one of the three existing flotation columns followed by mechanical scavenging and cleaning was developed. Detailed engineering was completed in September 1996. Construction started in February 1997 and was completed in 3 months at a cost of $3.2 million. An on-stream X-ray analyzer was installed to provide real-time arsenic and iron analyses and inferred sulphur value on some of the flotation streams.The new flotation circuit proved to be an instant success. Flotation tails values were reduced by 27%. Final tails solids and solution was reduced from 0.035 to 0 023, and 0.0014 to 0.0006 oz/ton Au, respectively. Based on a mill throughput of 1,620 stpd this decrease in tails value will result in an increased gold production of 7,500 ounces per year. The payback for the project is estimated to be around one year.This paper describes the evolution of the project from bench scale testing to commissioning. Also, the operational and economic impacts on down stream processing are highlighted"

Jan 1, 1998

"Chairman: Dr W. S. RAPSON Rapporteur: Mr J. W. WILSONPapers:Computer applications in rock mechanics by F. H. Deist, E. Georgiadis and J. P. E. Moris Rock mechanics in the design of mine layouts by K. Hodgson and N. G. W. Cook Automated regulation of mine ventilation by P. NiskanenThe rock mechanics papers, because of their complementary nature, were presented in succession and discussion on both followed directly. The paper on automated ventilation control at a mine in Finland was then presented and the session was closed with several contributions to this paper.By and large the papers and discussions which followed in this session showed how a classic tie-up had developed between the use of computing techniques in important fields of mining, and their practical application. In fact, the dis-cussion following the rock mechanics papers showed clearly that without the aid of high-speed digital computers the rate of progress in applied research in deep-level hard-rock mines, would have been severely hindered. Furthermore, it became apparent from the comments made by several contributors that the rock mechanics techniques and computer progress described in Deist's and Cook's papers could be used to provide useful data in the solving of rock mechanics and design problems on mines other than flat dipping deep tabular deposits.The paper by Niskanen, which described an automated ventilation control system at a mine in Finland, showed how effective computers could be in areas where the reversal of mine ventilation occurs due to severe seasonal temperature ranges. Although the system described in the paper could not be introduced easily in complex underground mines, several contributors gave examples of similar ventilation problems that could be solved mechanically,In introducing his paper, Dr Deist said that the purpose of the paper was to give a brief account of some of the programs designed by himself and his co-authors to aid in the solution of rock mechanics problems,The first system presented by Dr Deist was known as MINSIM in the South African mining circles. This system was designed specifically to aid in the solution of rock mechanics problems in the South African gold mining industry. It was particularly designed to handle tabular deposits at great depth but it has been used satisfactorily on a number of occasions to obtain at least approximate solutions in other mining situations. Dr Deist said that the principles embodied in the programs were easily extended and, in fact, there was a project in progress at that time which was aimed to do this. He said that the principles could easily be extended to shallow-depth mining at steep or very steep inclinations."

Jan 1, 2014

By Robert T. Beckman

The results of a preliminary investigation of compressive strength versus length-diameter (L/D) ratios of potash specimens and the statistical treatment of the data are summarized in this report. The purpose of the study was to evaluate a laboratory method for obtaining estimates of the strength of potash pillars during robbing operations. The specific objectives of this preliminary investigation were to test the method and the reliability (confidence limits) of the data, and to determine the number of additional specimens necessary for given confidence limits. The specimens were taken from three sites at two mines in New Mexico. The statistical analyses included the determination of the confidence limits for the data and the number of additional specimens necessary to obtain confidence limits of ±500 and 100 psi. The testing method was found acceptable, and estimates of the comprehensive strength, within 1500 psi, could be obtained by testing about 110 additional specimens from the three sites. The compressive strength of the specimens tested fits an empirical equation of the type

Dec 1, 1963

By AIME AIME

THE Annual Meeting-numerically the 162d meeting-of the American Institute of Mining and Metallurgical Engineers will be held at the Pennsylvania Hotel, 7th Ave. and 33d St., New York, Feb. 18-22, with the exception of the following events: the Mineral Industry Education Division will meet Sunday afternoon and evening at the Columbia University Men's Faculty Club, 400 West 117th St.; and a meeting of the Section Delegates, the annual business meeting of the Institute, and an executive session of the Board of Directors will be held in that order Tuesday afternoon in the Engineering Societies Building, 29 West 39th St., where the Directors will meet in the evening following their annual dinner to the Section Delegates. The Pennsylvania--one of the Statler group of hotels-was selected as headquarters because it has the physical equipment and facilities-for registration, technical sessions of all sizes, luncheons, social events, etc.-as well as the prominence and location desirable for an Institute annual meeting. (A tip for Tuesday afternoon and evening: You can walk underground from the Pennsylvania to within half a block of the Engineering Societies Building,)

Jan 1, 1945

By Ramana G. Reddy, Yudong Li

Numerical modeling of the thermal plasma process was carried out based on the thermal plasma reactor in our lab and confirmed using experimental data. The inlet boundary conditions of a non-transferred DC arc thermal plasma reactor were used in modeling the temperature and fluid flow distribution in the reactor. Different mesh grid sizes were used to confirm the model is independent of grid size. Temperature profile and gas flow distribution in the thermal plasma reactor were developed by the computational fluid dynamics (CFD) with ANSYS Fluent. The predicted temperatures are in good agreement with the experimentally measured temperatures in the reactor. The influence of plasma torch input power as well as the plasma gas flux on the temperature distribution was investigated using this model. The influence of power input and gas flow rate on temperature and velocity distributions are not independent. Generally, higher power input and lower gas flow rate will give rise to the temperature increase in the reactor.

Mar 1, 2017

By Jon K. Ahlness

The Bureau of Mines conducted laboratory and field experiments to determine tne amount of permeability reduction in uranium sandstone after its exposure to different drilling fluids. Seven polymer and two bentonite fluids were laboratory-tested in their clean condition, and six polymer fluids were tested with simulated drill cuttings added. Sandstone cores cut from samples collected at an open pit uranium mine were the test medium. The clean fluid that resulted in the least permeability reduction was an hydroxyethyl cellulose polymer fluid. The greatest permeability reduction of the clean polymers came from a shale-inhibiting synthetic polymer. Six polymer fluids were tested with simu-lated drill cuttings added to represent field use. The least permeability reduction was obtained from a multipolymer blend fluid. A field experiment was performed to compare how two polymer fluids affect formation permeability when used for drilling in situ uranium leaching wells. For this test, the polymer fluid with the best laboratory results (multipolymer blend) was compared with a commonly used polymer fluid (guar gum) that gave poorer laboratory results. When fluid injection rates for the four wells drilled with the guar gum were compared with those for the four drilled with the multipolymer blend, no statistically significant difference was found.

Jan 1, 1984