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By P. Somasundarrtn, A. Sivakumar

Flotation of minerals is governed by many processes at the solid/liquid/gas interface, such as adsorption and precipitation of surfactants. In this paper, the basic principles governing these processes and hence flotation are discussed. Also, recent techniques such as fluorescence and ESR spectroscopy which have been used to study in situ surfactant adsorption and to obtain information on the structure of adsorbed layer are discussed.

Jan 1, 1987

By Lance R. Barron

The U.S. Bureau of Mines, in cooperation with a central Utah coal .mine operator, began a study in July 1988 into longwall gateroad designs applicable to deep, bump- prone mine conditions. Prior to the study, four adjacent longwall panels, incorporating a variety of panel entry configurations using "yielding' chain pi liars, experienced severe bumps and coal outbursts at the face and in the tailgate pillars during panel extraction, resulting in several lost-time accidents and a fatality. To quantify those factors primari1y responsible for bump occurrences during panel retreat, a field investigation was initiated to confirm the anticipated performance of a two-entry gateroad system employing a large, nonyielding chain pillar design. Hydraulic borehole pressure cells and roof-to-floor closure [convergence) measurement stations were installed to monitor gateroad abutment loading and entry closure during panel extraction. Study results indicate that very high confinement of the coal seam by strong roof and floor members existing across the entire property, in conjunction with overburden depths in excess of 1.600 feet, provides for bump-scale energy storage in not only gate pillars, but along the entire periphery of the active mining area. Insufficient gate pillar designs were also identified as possibly enhancing the occurrence of bumps in the tailgate and adjacent face areas.

Jan 1, 1990

By Dennis Dolinar

In general, the direction of the maximum horizontal stress in the eastern United States is fairly well defined. However, the variation of the magnitudes of the horizontal stresses is not very well understood. Because the horizontal stresses cause severe ground control problems in underground coal and limestone mines throughout the eastern United States a more complete understanding of how the magnitudes vary would be useful for developing mine design strategies to combat horizontal stress related ground control problems. Therefore, in this National Institute for Occupational Safety and Health (NIOSH) study, the variation of the magnitude of the horizon stresses in sedimentary deposits in the eastern and Midwestern United States are examined with respect to two factors, the elastic modulus of the rock and the site depth. Stress measurements from thirty-seven sites are used in the evaluation. Examining the applied excess strains indicates that the eastern United States can be, separated into high and low strain zones. For most of the eastern United States the maximum applied excess or tectonic strain ranges from only 300 to 550 micro strains. However, there is one area, a portion of the Beckley seam in the central Appalachian region where the strains are significantly higher than the other regions. In this higher strain zone, the maximum applied tectonic strains range from 700 to 1,000 micro strains. Regression models for each zone based on the elastic modulus can explain between 83 to 85% of the variation of the maximum horizontal stress. Because one region, the northern Appalachian district, has strains that are about 20% higher than the other regions in the low strain zone, multiple strain models based on geographic regions were developed for the low strain zone that can explain 87 to 91% of the maximum horizontal stress variation with the elastic modulus. Depth was found not to be a significant causal factor in any increase in the horizontal stress even though the site depths ranged from 275 to 2,500 ft. Beyond a theoretical increase, based on Poisson's effect and gravity, no other increase in the horizontal stress with depth can be justified with this data. The most significant factor controlling the variation of the maximum horizontal stress is the elastic modulus of the rock, not the overburden depth.

Jan 1, 2003

By J. Chipman, N. J. Grant, E. C. Roberts

An equilibrium study was made of the distribution of chromium and oxygen between liquid iron, containing less than 1 pct Cr, and simple slags of the CaO(MgO)-Si02-FeO-Cr& type in the temperature range 1526' to 1734OC. The effects of slag oxidation, temperature, and basicity were observed. IN spite of the fact that chromium is one of the most important alloying elements in steel, and exists in almost all steels as a significant residual element, little research has been done to determine its behavior in basic steelmaking processes. Considerably more work has been done under silica-saturated acid slag conditions. Korber and Oelsen,' Herasymenko,' and others have generally agreed that in acid steelmaking practice the chromium in the slag behaved as if it were present as the chrom-ous ion (CrO). Work by Hilty- ir, high chromium slags also indicated that chromium may exist as CrO. In basic slag systems no equilibrium data exist. Based on individual studies of basic open hearth and electric furnace practice, Bardenheuer," Rock-rohr,% nd HauckQ oncluded that: 1—chromium recovery increased with decreasing basicity, and 2— chromium recovery increased with increasing temperature, although the effect was small. In similar studies Yavioskii and Dzemyen' concluded that: 1— slag FeO is the most important variable, 2—the basicity of the slag has no effect on chromium recovery, and 3—slag viscosity is not high even when 20 pct Cr,O, is present. Lapitskii\ oncluded that chromium recovery improved as the basicity of the slag decreased and increased with increasing manganese in the metal. Regarding the effectiveness of CrZ08 as a base or acid in basic slags, both Kristofferseno and Trojer" reported that Cr,08 was an acidic component requiring neutralization as 2CaO-Cr,O,. Experimental Procedure The experimental apparatus and procedure used for the present research were similar in most details to those used by Winkler and Chipman" and were described in detail by them. A magnesia crucible was used, holding 60 to 80 lb of Armco iron which was decarburized with hydrogen to about 0.010 pct C. Since all the metal samples solidified without gas evolution, this carbon level was assumed not to be significant. Synthetic slags made by mixing pure oxides were used throughout the study. Temperatures were measured by means of calibrated W-Mo thermocouples and were checked by Pt-Pt-Rh thermocouples. The range of temperatures covered in this study was from 1526" to 1734°C. The chromium content of the iron was in the range 0.032 to 0.82 pct, although the bulk of the tests showed 0.04 to 0.2 pct. The slags were of the CaO(MgO)-SiO,-FeO-Cr,O, type in which the Cr,O, content was from about 2 to 20 pct, although most of the slags showed from about 2 to 10 pct. The FeO range was from about 10 to 65 pct. CaO and SiO, were in the range of about 5 to 45 pct each, yielding a rather wide range of basicity values. The first 12 heats were made without a sulphur addition, and with only 30 min allowed for slag-metal equilibrium to be reached. In previous research it had been shown that less than 30 min was adequate to achieve equilibrium in slags free of Cr2O8.11,14.15 A study of the present data indicated that some of the tests may not have reached equilibrium in this time; accordingly four additional heats were made in which at least 1 hr was permitted for equilibrium to be reached. For reaching

Jan 1, 1955

By J. P. Rider

The number of extended cut mining systems has increased significantly in coal mines over the last decade, and there is a constant push to extend the face ventilation systems to even greater setback distances. The need to maintain airflow at setback distances of 12.2 m (40 ft) and beyond requires that methods for delivering intake air to the face be improved, or alternative ventilation techniques be implemented. The emphasis of this research effort was to examine various techniques to improve the distribution of available air at the mining face in order to reduce face methane levels. A study was conducted comparing the performance of a jet fan, used in conjunction with a machine mounted scrubber, with blowing curtain ventilation in a 27.5 m (90 ft) heading. In addition, a second study was performed on blowing curtain systems examining how scrubber flow, intake air velocity, and curtain setback influence face methane concentrations. Results showed that when the heading advances to a depth of 27.5 m (90 ft) blowing curtain systems were more efficient at diluting face methane levels when compared to a jet fan. Also, increases in scrubber flows and curtain velocity resulted in lower face methane concentrations for blowing curtain systems at 9.2 and 15.2 m (30 and 50 ft) setbacks.

Feb 24, 1997

By E. P. Miller, F. R. Morral

Hot-dipped heat-treated zinc coatings on sheet steel were examined with X-rays. The phases identified were compared with those listed in the modern literature 01 the zinc-iron system. The zeta (FeZn13) phase is shown to correspond to the phase found by Schueler (1925) in heat-treated zinc coatings. An investigation was undertaken to determine the phases present in hot-dipped heat-treated zinc coatings on steel sheets and wire. This kind of coating on wire was studied some years ago by Schuelerl by microscopic and chemical methods. He reported a new phase, FeZn10. Later, Clark and Stillwell,2 using X-ray crystal analysis, identified a new phase in ordinary galva. nized wire, which was assumed to be the FeZn10 phase. Since the extensive review of the iron-zinc alloys presented a few years ago,3 much new work has been published, some of which5-l6 was too late to be included in the recent edition (1939) of the American Society for Metals' Handbook.4 Figs. 1 and 2 are reproductions of the latest iron-zinc diagram proposed by Schramml1 as a result of his investigations by microscopic, thermal, magnetic susceptibility and X-ray methods. Table 1 summarizes all the known published X-ray data of the phases Present. The solubility of iron in zinc has been determined by x-ray methods.10 In the same manner the homogeneity range of the P phase was studiedlo using the principle that the parameter of an intermetallic compound changes while the concentration of One of the constituents changes. Schramm10 has found some 80 alpha lines in X-ray powder photograms of phase d1, and from these he believes that this phase is related to the P phase. Previous investi-

Jan 1, 1941

By D. S. Jacobus

The boiler here referred to was of the water-tube type, having 2535 square feet of heating-surface, which the makers held to be capable of generating 325 horse-power of steam; this being understood to mean that 325 times 30 pounds of water would be evap-

Jan 1, 1889

By Hugh Boyd

Jet pulverization is a relatively new tool for fine grinding. It is not yet in general use in the mining and ore dressing fields, since most of the requirements in these areas have been for relatively coarse particle sizes. As the need for finer grinding increases - because of different ores, new products, and new values being sought - jet pulverization will, increasingly, be properly used.

Jan 1, 1969

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

FATTY acids have been used as standard collectors for floating the matrix1-8 but not the leached zone phosphate ores. After a series of investigations, Davenport9 and Tarbutton10 concluded that the Florida leached zone ores tested were unamenable to fatty acid flotation and must be upgraded by floating the siliceous gangue with Armac-T as collector. The cationic flotation was estimated11 to cost almost ten times as much as a fatty acid process that would ideally give the same flotation grades and recoveries of phosphates. Mineralization: Extensive deposits of leached zone aluminiferous phosphate occur in The ore sample used for this work was obtained from the Virginia-Carolina Chemical Corp., Clear Springs area, Florida. The ore is a potential source of uranium and aluminum as well as phosphorus. Since the uranium and the recoverable aluminum are contained in some of the phosphate minerals, an upgrading of phosphate results in a corresponding enrichment of both uranium and aluminum. The phosphate minerals in the ore are primarily pseudo- wavellite, millisite, and carbonate fluorapatite, with a minor amount of wavellite. Quartz and clay are the common gangue minerals, quartz being pre- dominant. Others present in small amounts are ilmenite, hydrated iron oxides, staurolite, monazite, and zircon.

Jan 1, 1957

By Alan Peacock

Shield supports have been in use in the USA underground mines since 1975, and their development in the intervening time has been progressive and inovative. Specialized techniques are used to optimize their performance in a particular application and to design the component parts.

Jan 1, 1981

By J. J. Bowman

The term "secondary aluminum" frequently is used loosely and often is considered synonomous with "inferior quality." Under war conditions, when every pound of material must contribute its share to the job at hand, this type of thinking is most unfortunate. Actually, given a supply of segregated scrap, an experienced smelter can produce remelted ingot of good quality, comparing closely to the analysis of the original material, and of considerable value of the war effort. The alloys he can produce are, of course, somewhat controlled by the analysis of the available scrap and, by the very nature of things, some of his production is not suitable for indiscriminate use. However, remelted scrap ingot provided about 273,2 per cent of this country's domestically-produced 1942 aluminum supply and probably will comprise about 39 per cent of the 1943 supply. (Canadian production is excluded from these figures.) That this part of the supply remains important is indicated by a recent report that "requirements" for the second quarter of this year were about 14 per cent greater than the supply, even though that supply will be almost twice the prewar annual production. (And those requirements, incidentally, were prepared after many conservation measures had been taken into account.) Since W. Bonsack recently has published a paper2 on the effects of the various alloying elements and impurities on the properties of aluminum, and such con¬siderations really are the important ones in a discussion of the metallurgy of secondary aluminum, it is planned to restrict this discussion more to a consideration of the sources, general characteristics and possible uses of these materials. For the purpose of this discussion, mill (or run-around) scrap may be disregarded and only plant scrap and obsolete scrap considered. Plant scrap, of course, is that scrap which is generated during the production of some part or assembly from a fabricated form of aluminum, such as sheet, tubing, forgings, castings or the like, and it may consist of solids (including rejected parts or subassemblies) or of machinings. To the extent that the several alloys are effectively segregated and the material is properly identified, the composition after remelting can be rather closely controlled or predicted. Obsolete scrap, on the other hand, is the "junk" which accumulates because of the wearing out or breakage of some piece of equipment. Although it is almost always in the form of solids, the accumulation includes many different alloys (often in the same assembly) and may include a considerable amount of nonaluminum material. The "metallics" recovered from drosses also contribute a portion of this class of material. The composition after remelting, therefore, may vary over rather wide limits and can not be very accurately predicted in any specific instance. SEGREGATION OF PLANT SCRAP Unfortunately, perhaps, it was not very common practice before the war to

Jan 1, 1943

Strong markets for metals and energy over the past five years have supported equity and debt market funding to enable a new group of mining juniors to emerge in control of economic resources, some in regions with high investment risk. As companies drive these projects to development, production and positive operating cash flow, their Boards and CEOs are confronting important questions:Having achieved initial success, what is our longer term purpose as a company? Does the purpose originally described in the Initial Public Offering to raise equity remain wholly relevant? Given that purpose, how do we understand the available sets of opportunities and related risks? Should we be acquiring new assets or other companies, or developing the existing portfolio? What commodity sectors and geographies should we focus on? Or should we be conserving funds until asset prices or project costs provide greater assurance of value to shareholders? How do we translate that purpose into tangible goals that shape and direct the work of people in the organisation? How do we get the right work done in the face of high turnover and competition for capable staff? Drawing on the authorÆs career experience and on work undertaken by Heuris Partners, this paper provides a practical CEO framework for strategy development, organisation design and on planning the work of the business in the mining industry.

Jan 1, 2006

By E. P. Reed

We are proud that one of our predecessor companies originated the phrase "Safety First". That phrase remains today as the guiding principle that governs our total approach to safety and well being in U. S. Steel. U. S. Steel management is totally committed to this attitude and our objective is to have every employee as deeply conscious of his safety responsibilities. Safety is a state of mind but like most things it must have a physical side - both intertwined and inseparable. You might say each promotes the other; and this gives us confidence that with hard work, cooperation from all individuals, and proper application of knowledge and experience, our ultimate objective of frequency "0" will be attained. It is in this vein of thought we present a paper today which gives you briefly our progress, mainly in the physical, or mechanical, protection of miners at work in the Southern District mining operations of U. S. Steel. The Southern District not only includes the underground mining of coal but the underground mining of zinc ore in Jefferson City, Tennessee, and the quarrying of dolomitic limestone near Bessemer, Alabama.

Jan 1, 1970

By Davies K. E

Several nuclear techniques have been assessed for application to online conveyor belt analysis of oil yield from Rundle oil shale. The most favourable technique is neutron inelastic scattering which determines the total carbon content of bulk shale samples. Correlations of chemical laboratory assays for 540 Rundle oil shale samples show that oil yield can be predicted from total carbon to within 11 litre/tonne.Laboratory experimental work on 17 bulk samples of Rundle oil shale indicated that carbon and oil yield can be determined to within 0.6 wt per cent and 9 litre/tonne, respectively, using the neutron inelastic scatter technique. A practical neutron inelastic scatter gauge for application on a 23 mm thick reinforced conveyor belt could consist of a 5 curie 241 Am-Be neutron source and a 150 mm diameter x 100 mm thick Nal(TI) detector. With this gauge, the analysis time to achieve a counting statistical error of 6 litre/tonne should be about five minutes.

Jan 1, 1985

By J. F. Henderson

Stable mining operations commenced in the Northwest Territories in 1933. Pitchblende from Great Bear lake and gold from the Yellowknife district are the main minerals produced. The value of pitchblende products produced from 1933 to 1941 was nearly $6; 000; 000; data on subsequent production are not available. The first gold was produced from the Con mine at Yellowknife in 1938. Other properties that later came into production include the Negus; Slave Lake; Thompson Lundmark; and Ptarmigan mines. The annual gold production reached $3; 862; 000 in 1942 but due to the war and consequent labour shortage fell to $333; 218 in 1945. The only producing mines at present (May; 1947) are the Con and Negus; but several promising properties are under development; including that of Giant Yellowknife Gold Mines where large tonnages of ore are being blocked out. With the reopening of former producing mines and new production from properties now being developed; gold production should rapidly increase and exceed its former peak within the next few years.

Jan 1, 1954

MELTING in a hearth and in a basket is almost the same thing; charcoal and bellows are used for both. These are made large or small according to the quantity that you wish to melt, and more or less force of the bellows is applied according to the need. The hearth, bowl, or refinery, as the masters call it, is made with bricks and clay like a forge; opposite the middle of the tuyère a round hole is made like a wash- basin, wide at the mouth and narrow at the bottom where there is a hole for emptying it. A little iron plug is put in this so that it may be closed when necessary, or a piece of brick that is cut and pointed. Now, when this has been well covered all over with ashes, and the tuyère has been arranged so that the wind strikes the center, it is first filled with charcoal and baked very well so that the metal may be kept hot once it has been melted. When it has been baked, it is again filled with charcoal, fire is applied, and it is left to inflame gradually by itself. Then put one or

Jan 1, 1942

By James A. Holtkamp

Environmental regulation in Mexico has matured dramatically and effectively in the last decade. The gap between environmental regulation in the United States and Mexico is rapidly narrowing. From a regulatory perspective, it is no longer necessarily less burdensome to operate in Mexico. Principal laws and regulations Mexico has two principal environmental regulatory systems. The first consists of the laws and regulations governing domestic activities. The second consists of the treaties, agreements and understandings between the United States and Mexico dealing with transboundary pollution and maquiladoras (see Maquiladora Decree, next column). The following are the principal major laws and regulations governing environmental protection in Mexico: General Law: The General Law on Ecological Balance and Protection of the Environment, effective March 1, 1988. Water Regulations: Regulations for the Prevention and Control of Water Pollution, effective May 29, 1973. Environmental Impact Regulations: Regulations of the General Law on Ecological Balance and Protection of the Environment, regarding Environmental Impact, effective June 8, 1988.

Jan 1, 1994

By Ralph H. Cleland

GENERALLY speaking, the Industry lost ground in 1941 in its accident experience. Though the frequency of compensation accidents was but slightly higher than in the previous year and well below past experience, our fatality rate shot up to that obtaining in 1938, and the average cost per man employed was the highest for some time. The number of fatalities was 56 in 1941 as against 33 in 1940. The average cost of compensation per man employed was $34.25 in 1941 as against $28.43. There was but a slight increase in the number of men employed. Accident prevention efforts were maintained, as shown by our frequency, but our accidents were of a more serious nature. In a period of considerable labour turnover, with many new men entering the Industry, especially the base-metal division, and much mental distraction, we might well have expected a high rate of accidents. That this did not occur is a tribute to managers, supervisors, and workmen alike. We all regret the high fatality rate and one must consider why this occurred. So far as it is possible to determine, there is no apparent explanation. There were no disasters. The accidents occurred to the same class of work-men, both in respect to jobs and age groups, and from the same age-old causes that we all know so well. Luck is a big factor in the seriousness of an accident; the solution lies in preventing accidents, even first-aid cases. Generally speaking, if minor accidents do not occur, major accidents do not occur.

Jan 1, 1942

By S. H. Moll, R. E. Ogilvie

The investigation of solid-state diffusion phenomena may lead to much information concerning binary alloys. In particular, a study of the concentration gradients present in multiphase diffusion couples can lead to the determination of the solubility limits of the single-phase fields in the phase diagram. The specific concentration gradient which results from the heat treatment of a diffusion couple depends not only upon the time and temperature of diffusion, but also upon the number of phases existing in equilibrium at the diffusion temperature. Such concentration gradients possess sharp discontinuities whose terminal points correspond to the solubilities existing at the limits of the two-phase field in the phase diagram at the diffusion temperature. In general, there will be a discontinuity in the concentration curve for each two-phase field which exists in the phase diagram between the concentration limits of the couple. A number of investigators have analyzed the gradients present in multiphase diffusion couples. 1-8 The iron-titanium phase diagram exhibits a y loop in the temperature range from 900" to 1400°C, and the limit of the a + y field lies at some composition which is less than 1 wt pct Ti for any temperature. It was felt that a diffusion study could yield values not only for the diffusion coefficients involved, but also for the chemical solubilities in the phase diagram. The concentration gradients were analyzed by an X-ray absorption technique developed by Ogilvie.6 The absorption of a monochromatic X-ray beam is measured in steps parallel to the diffusion direction and the resulting intensity gradients are transformed into concentration gradients by applying the laws of X-ray absorption in a binary system. This technique has been applied by ogilvie6 to the systems Ni-Au, Cu-Au, Fe-Cr, and Ni-Cr; by Gelles7 to the systems Be-Fe, and Be-Ni and by Hilliarde to the system Al-Zn. Linear X-Ray Absorption Analysis—The use of X-ray absorption analysis as a tool for determining concentration gradients arises from the fact that the beam is absorbed according to the quantity and species of elements present in the sample and not according to their state of aggregation. This method is more advantageous than the chemical analysis of machined layers since it is less time consuming and less expensive and can analyze a very small area. IF a homogeneous binary alloy (A + B) is analyzed with two different monochromatic X-ray beams I0(2) and lo(2) the following relation between the transmitted intensities, the intrinsic absorption coefficients of A and B for the two different radiations and the weight fraction of each element may be derived.' In (I/Io) (a+b) xa(u/p)a(2) + xb(u/p)8(2) Eq. [1] is independent of specimen thickness and density, but requires that either element A or B possess an absorption edge between the wavelength limits of the two monochromatic beams. I, is evaluated for each radiation by measuring the transmitted intensity through a varying number of foils of a suitable absorber. A plot of the natural logarithm of the transmitted intensity as a function of the number of foils, when extrapolated to zero foils, yields the value of I,. If a plot of the ratio in Eq. [ I] is calculated as a function of xA, then a master curve results. From

Jan 1, 1960

By J. E. Gruzleski, O. Knacke, M. J. Meixner

The evolution of CO from small specimens of solidifying steel was investigated using a thermobalance technique. Gas evolution begins in the temperature range between 1400" to .1450°C. This behavior is independent of the initial carbon content and the cooling rate. At a constant temperature above 1220°C, the rate of gas evolution is temperature independent. Out-gassing of the specimen is thought to proceed through small channels formed by the coalescence of bubbles between dendrites. LIQUID metals have a higher solubility for gas than the solid. During freezing, these gases form bubbles which may either escape or remain trapped in the solid. Recent work1 on the evolution of oxygen from solidifying silver showed that the gas is not liberated until a large fraction of the melt has solidified, and that the gas is evolved in an almost explosive manner. Because of the commercial importance of CO evolution in solidifying steel, a similar investigation was undertaken to study the mechanism of gas liberation in steel. EXPERIMENTAL The thermogravimetric method of Knacke and eixner1 to follow gas evolution by weight changes was employed. Weight differences of 0.1 mg could be reproducibly measured on specimens weighing 2.5 g. These specimens were taken from alloys with varying carbon contents from <0.01 to 0.11 wt pct and <0.01 wt pct of each of silicon, manganese, and aluminum. Specimens contained in 8 mm ID magnesium alumi-nate crucibles were heated to 1550°C under 1 atm of very pure (99.995 pct) CO with a tungsten resistance furnace. The specimen temperature was measured with a Pt-Pt/Rh thermocouple located directly beside the crucible. It is felt that the temperature thus measured was within 5" to 10°C of the specimen temperature since on fusion the weight of the specimen increased due to uptake of CO, and this weight increase was always observed to begin within the temperature range of 1530" to 1540°C. Even after 3 hr there was a small weight increase with time indicating that the molten specimen was not completely saturated with CO. Therefore, complete saturation was not attempted, and all specimens were simply held for 3 hr at 1550°C before cooling. Two types of cooling experiments were performed. One consisted of continuous cooling at linear rates from 5°C to 20°C per min down to 1020°C. The second type of experiment involved continuous cooling at 10°C per min to a predetermined temperature, and then holding the specimen at this temperature for a certain time. During all of these experiments, the sample weight was recorded as a function of time and temperature. OBSERVATIONS Continuous Cooling Experiments. No gas evolution was detected above 1450°C. The initial weight decrease always occurred between 1400" and 1450°C with the average at 1430°C. With further cooling, gas evolution continued to about 1150°C. Between this temperature and 1020°C no further outgassing was observed. This behavior did not seem to depend on the initial carbon content nor on the cooling rate in the range investigated. Typical patterns of gas evolution are shown in Figs. 1 and 2 for different initial carbon levels and cooling rates. The total amount of gas liberated during solidification varied with the rate of cooling. The total weight change on continuous cooling at a rate of 10°C per min

Jan 1, 1970