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By J. W. R. Rayner

THE conventional method of making water gas involves individual plants for the separate carbonization of coal to coke and the subsequent gasification of coke with steam. The process demands lump coke, preferably made from the best quality of coking coals. The ash in the coke should have a high melting point and the gasification process suffers a loss of efficiency when cokes with law ash-melting points are used. In Britain, these coals are generally the most expensive and they are readily available only in certain localities. The coals not suitable for making lump coke, or yielding only poor quality coke, are much more widely available and are generally cheaper. DEVELOPMENT OF ALTERNATIVE PROCESSES In Germany, processes have been developed and operated commercially for the production of water gas from very low-rank coals such as brown coal and lignites, but much less effort has been spent on processes to use coals of intermediate rank, which are widely available in Britain. The brown-coal processes use coal in the form of either dust or briquettes. The most successful of the dust-gasification methods is the Winkler process, which made a substantial contribution to German oil production during the war. It uses coal in the site range 0 to 8 mm and the fuel bed is blown with a mixture of oxygen and steam at a rate high enough to give it a characteristic boiling motion or, in present-day phraseology, at a rate more than sufficient to fluidize it (Fig. 1). Air cannot be used to provide the heat required for gasification, for various reasons. In the first place, to make the process continuous by mixing air and steam would involve the production of a lean gas-containing much nitrogen. If a separate blow were used, a large amount of potential heat would be lost because the blow gas in such a process would contain a very high percentage of carbon monoxide. Oxygen is necessary therefore and oxygen remains relatively expensive for use in gasification. In the Winkler generator, formation of clinker caused by local overheating does not occur, because of the mobility and high heat transfer of a fluidized bed. These properties of fluidized dusts have been used most successfully

Jan 1, 1953

By Harry Gard Knox, F. R. Harris

This paper covers some of the problems presented to the oil industry in the drilling of oil wells in the open waters of the Gulf of Mexico. The hazards, delays and relative costs of offshore drilling are reviewed and various forms of drilling platforms discussed. The requirements of the offshore drilling rig are summarized together with the principal items affecting the cost of construction. Sea waves and their size and characteristics as affecting offshore platforms are reviewed. Drilling platforms are classified as fixed, or fixed and floating. Fixed platforms of the conventional cofferdam and pile-supported type are discussed together with their good points and their limitations. The desirability is pointed out of eliminating as much offshore work as possible where operations are subjected to constant and expensive delay and substituting therefor the prefabrication of structures ashore or in sheltered waters. Marked economy will come with the standardization of offshore rigs aid special means of transporting them to the site. Several types of structure which are partly pile-supported and partly buoyancy-supported are discussed and their possibilities of future usefulness commented upon. General Considerations The predominant attribute of offshore drilling equipment is that it must be equal to the job in hand. We therefore give first thought to the matter of adequacy. In view of the probable depth of drilling, the investment involved and the per diem labor costs, it is assumed heavy modern drilling equipment will be employed. In order to usc such equipment efficiently, the working deck must be ample in size and strength and supported so as to be relatively free from motion and from green seas even in heavy storms. These requirements necessitate a high and rigid land-based support for the drilling rig and machinery with plenty of space for supplies, such as pipe, mud, water and fuel, with reserves for days when transportation from shore is impracticable. In offshore rigs the crew will be housed onboard in comfortable quarters, probably air conditioned and equipped with a galley and refrigerated food storage. An important consideration will be the ability to transfer stores and crew to and from the rig in all but the heaviest weather and the platforms must be protected from the impact of supply vessels when alongside. It will be essential to maintain continuous communication with shore by radio or cable, not forgetting the possibility of a helicopter landing space for the transfer of crew and light stores as well as a means of general communication. Whatever structure is constructed must be secure from storms of hurricane force and a safe place for the operating crew to work. If the well comes in, the drilling rig will presumably be removed and a small but rugged pile-supported platform will remain to carry the Christmas tree with safe working space around it. It will be protected from damage on all sides by buffer piles or dolphins. It is assumed that the flowing oil will be piped to storage tanks in the vicinity of the well. An individual tank for each well or a

Jan 1, 1949

By Michael P. Richardson

INTRODUCTION This paper is intended to be a summation of the state-of-the-art i n draw theory and draw- point spacing. Knowledge of this very important factor in the successful design and operation of a block caving mine is scarce and nonconclusive. It is hoped that the presentation of this paper will stimulate interest and discussion which will lead to a stronger understanding of these a1 1 important factors. Please note that block caving as used here- in refers to block, panel, and mass caving systems in general, not just to the specific system of block caving where discrete blocks of ore are prepared and caved as a unit. DRAW THEORY The knowledge of draw theory as related to the practice of block caving mines is, unfortunately, very limited. In recent years much work in draw theory has been done in respect to sublevel caving systems and an understanding of draw mechanics relating to sublevel caving seems to be emerging. This work is certainly helpful to those of us interested in block caving but the question of "what goes on up above" still hounds us since we are more interested in the region of draw which begins just above the area where sublevel caving interest ends. Herein is presented a brief summary of draw theory with an attempt to look at the factors which can help our understanding of the area of draw influence in block caving mines. Nature of Gravity Flow An understanding of the flow of granular material (rock, sand, grain, or prill as examples) is the first step toward understanding block caving draw. If we take a supported column of granular material and allow gravity flow through an aperture at the bottom of the column, an ellipsoidal shaped zone of disturbance of the in-place material will form and grow with extraction of material through the aperture. The volume of this zone of disturbance or loosening is about 15 times the volume of material extracted at any given time (Kvapil, 1980). Figure 1 shows the development over time of the zone of disturbance. The ellipsoid of disturbance represents a future ellipsoid of extraction which will equate to the volume of materia1 extracted by that future time. Extraction involves the movement of the particles located vertically over the drawhole directly downward while material outside this direct vertical volume moves radially inward and down toward the drawpoint as shown in Figure 2a. Figure 2b shows the result of this motion on originally horizontal strata within the ore column. Increased draw increases the eccentricity of the ellipsoidal volume or, in other words, the ratio of the height over the width of the disturbed area increases as ore is withdrawn from the column (Kvapil , 1980). This becomes important to block caving since eventually a vertical cylinder of draw will be approximated as this ratio increases without bounds. Figure 3 shows this result. The width of this draw cylinder is a critical dimension for the determination of draw point spacing in relationship to block caving mine design. McCormick (1968) for one, felt that within this cylinder of draw, mass flow would take place. This is the

Jan 1, 1981

By Julian M. Avery

IN its dual role of pig-lion smelter and gas producer, the blast furnace is a remarkably satisfactory and efficient apparatus Many metallurgists and engineers have pointed out, however, that since the primary function of the blast furnace is to produce pig iron at the lowest possible cost, its function as a gas producer should be subordinated to this primary purpose During the past 10 years or more, improvements in blast-furnace technique and economy have, n fact, been directed primarily to increasing efficiency n the use of the reducing power of the gases produced by combustion of coke at the tuyeres, to reduce iron ore within the furnace The net over-all result is a decrease n the fuel value of the top gas per unit of volume, and per ton of pig iron, which is evidently amore than offset n value by the corollary saving in coke and the possibility of increased furnace capacity, for otherwise there would be no point in making such improvements The purpose of the present paper is to suggest that, while progress has been made n this direction, there is another approach to the problem of increasing the chemical and thermal efficiency of the blast furnace in its primary role as a pig-iron smelter, which appears to offer possibilities of improvement in over-all economy of a different order of magnitude than results thus far obtained by the use of other expedients The present argument is based in large part upon the hypothesis that the efficiency and economics of pig-iron smelting are seriously and adversely affected by the phenomenon known as "solution loss," and that the problem of solution loss can be successfully attacked by increasing the over-all pressure, i e , the "top pressure" under which the furnace is operated It is indicated that pressure operation may also be expected to result n concomitant benefits, which may be summed up as generally improved operating conditions, together with a substantial saving in fuel and/or a substantial increase in furnace capacity In a broad sense, the suggestion of pressure operation of the pig-iron blast furnace is not new, for operation under moderately increased over-all pressure was suggested as early as 1871, by no less an authority than

Jan 1, 1938

Report of Secretary TO THE BOARD OF DIRECTORS OF AMERICAN INSTITUTE OF MINING AND METALLURGICAL ENGINEERS Gentlemen -I have the honor to present the following report for the calendar year 1920 The activities which-seem to call for special com¬ment are THE NEW FORM OF MAGAZINE MINING AND METALLURGY appeared every month during the calendar year and has been developed until it contains some ten departments It has brought forth more commendatory letters than have been received at headquarters on any other subject throughout the year Less than a dozen letters unfavorable to the change have been received, and the indications are that the magazine has met a want deeply felt, especially by members distant from headquarters The technical papers printed by the Institute are published in abstract in the magazine and opportunity is given to members who desire them to receive full copies of any or all papers published The Bound Volumes, as usual, contain all the papers in full and discussions thereof FINANCES The greatly increased cost of paper and printing has put a tremendous burden on the Institute's finances, since the dues of $12 per year are only 20 per cent greater than the members paid when the Institute was founded forty-nine years ago This has resulted in a temporary deficit, similar to that encountered by many of our sister engineering societies The fact that our Institute has lower dues and gives more in the way of publications to its members than any other of\the national engineering societies has rendered the situation more difficult for us MEETINGS The Annual Meeting in New York, the Field Meeting in the Lake Superior District, the meeting of the Petroleum and Gas members at St Lours, and of the Institute of Metals Division in Columbus, Ohio, have all been described in full in the magazine

Jan 1, 1923

By E. P. Whittemore

Experience with the ASC multipoint gas lift system was obtained in Colonia zone of the West Montalvo field near Oxnard, Calif. The wells in this pool produce from depths varying from 10,500 to 12,000 ft. Oil gravity is generally 14 to 15' API with a few extremes of 12 and 20" API. Some salt water is produced which causes some very viscous emulsions. Viscosities at 150F (which is the approximate wellhead temperature) vary from 5,000 to 100,000 SSU. Most of the production is by gas lift, although a few wells are produced by rod and hydraulic pump. About half of the gas-lift wells are on continuous flow and the remainder are on intermittent lift using large, ported, pilot-operated valves for single-point transfer of gas from casing to tubing. Gas-liquid ratios vary from about 6 to 10 Mcf/bbl of gross fluid lifted. Wells are produced to a 450-psi trap system. The following remarks will be confined to intermittent lift only, since this is the type of lift which has been achieved with the ASC valve system. The maximum gross fluid which has been produced by single-point intermittent lift is about 350 B/D in 3-in. tubing and 200 B/D in 21/2-in. tubing with gas-liquid ratios of approximately 7 to 9 Mcf/bbl. Some design changes could reduce this ratio. The ASC multipoint system has provided production as high as 480 BOPD in 21/2-in. tubing with gas-liquid ratios just under 4 Mcf/bbl. To be able to apply the multipoint system, it is recommended that a detailed explanation be obtained concerning transition-point pressure and stabilizer setting—what its significance is to the string design, how it may work for or against the operation of the well, how it is related to tubing sensitivity and how it affects the unloading operation. The unloading operation may only be of academic interest in a technical paper, but to the production foreman, unloading and setting the valves in operation is a very real problem and should be understood in detail. One item touched lightly in the paper was the unloading valve. This valve controls the maximum pressure at which the well can be operated. When lifting heavy viscous fluids, it is most important to set this valve for the maximum possible realistic operating pressure at the surface. If the well lifts easily, it is simple to set the ASC valves at a lower operating pressure and the unloading valve will remain closed; but if the well happens to be heavier to lift than anticipated, it may be desirable to operate on the unloading valve itself and use all the energy obtainable at the bottom of the hole. In the Colonia pool very heavy wet-gas gradients are experienced due to the viscosity of the liquid and the dense mist which is left behind a slug of fluid. There are many combination strings of 3- and 21/2-in. tubing. This aggravates the wet-gas gradient problem and provides wet-gas gradients of about 50 to 70 psi/1,000. An advantage which multipoint lift has provided is increased slug efficiency through better maintenance of pressure under the slug and decreased fall back as the slug passes up the tubing. By using multipoint injection, wet-gas gradients have been reduced to about 30 psi/1,000. This has reduced bottom-hole operating pressure and given a production increase. The ASC valve is not a simple device. It's operation is difficult to understand, and it must be understood to be used efficiently in gas-lift design. Operating problems are difficult to diagnose—whether they be caused by the fluid lifted, valve malfunction, lift gas rate, or operating pressure. Calculations and reasoning are required to find out what is causing the problem. Inherent in the ASC valve is the inability to create large pressure differentials across a slug. Large differentials may be required to overcome the inertia of very viscous fluid as it is being accelerated in the bottom of the hole. This is tied back to the design of the unloading valve and is one reason for the importance of setting the unloading valve for the highest possible operating pressure. ~u; to the narrow spread the ASC valves provide, it is impossible to cycle slower than about 24 cycles/day on choke control. If small production of 150 BOPD and less is expected, a surface time-cycle controller will be required if the most economical operation is to be achieved. To achieve a satisfactory operation, the operator must keep a record of any changes made in the operating pressure of the ASC valves. Anything which may cause changes in casing pressure in excess of the stabilizer setting will change the valve operating pressure, and if this is not noted from daily inspection of the well casing-tubing pressure recorder charts, the operator will lose control of the well. Significant results can be achieved using ASC valves; however, considerable knowledge is required to design with them, and attention to detail is required for satisfactory field operation.

Jan 1, 1965

By H. H. Rachford, D. S. Howard

In the withdrawal of fluids from tilted aquifers it is of value to be able to predict pressure patterns during the course of the pressure decline. As an example of this, in the displacement of fluids from oil reservoirs being produced by water-drive, prediction of the reservoir pressure is an important factor in fixing production rate. The prediction of pressure patterns in the depletion of an inclined aquifer has conventionally been made by solving the well known flow equations for the pressure Patterns in a horizontal aquifer, and correcting these patterm for the pressure difference due to the hydrostatic head associated with the vertical distance between a point in the horizontal aquifer and the corresponding point in the tilted aquifer. Inasmuch as the equation describing flow in tilted strata is different from that for horizontal flow. there was question as to the validity of the simple corrective procedure current1y in use. To examine the magnitude of error made using this procedure, an inclined aquifer was chosen for which the error was expected to he large, and the equation for flow in this tilted stratum was solved numerically. The results of the conventional procedure of correcting the solution of the equation for horizontal flow was compared with the solution of the correct equation by studying the difference between predicted pressures by the two methods. Three forms of the hydrostatic head correction were studied. The results for all three forms of the head correction are similar. The error in the approximate solution is quite dependent on the position of the horizontal aquifer with respect to the inclined one. The error is greatest at the producing end ad increases with amount of fluid withdrawn. The magnitude of the errors is not large if a good choice is made for the position of the horizontal datum. The most satisfactory position for the datum in all cases is near or slightly about the mid-point of the inclined stratum. Use of the best approximate method studied with the best datum tested yielded predicted pressures in error no greater than 7 psi. INTRODUCTION The movement of water by expansion from an aquifer to displace fluids from a contiguous oil reservoir was first recognized over 20 years ago.9 Since that time much work has been done to relate this mechanism to reservoir behavior mathematically. The result of this effort on the part of many workers has led to an understanding of underground fluid movement which has enabled us to follow and predict the behavior of the water-drive reservoir. One reason that good progress has been made in the application of mathematics to the study of pressure patterns and water movements in aquifers has been that the differential equation which describes this process is of a relatively simple form. The equation for the isothermal, horizontal, viscous flow of water through homogeneous sandstone is identical with that for the diffusion of heat through homogeneous solids, and this equation and means of obtaining solutions for it with many types of boundary conditions have been studied extensively. That this work has been highly successful is clearly emphasized by the large number of solutions developed for problems of interest both by methods of formal mathemat-

Jan 1, 1957

By S. M. Brisbane

THE life of refractory linings in rotary cement kilns can be shortened by uneven or inadequate support of the kiln and its shell and by variations in the conditions of operation. Alteration of these factors may, according to their nature, bring about mechanical deterioration of the lining or promote chemical attack. Chemical attack has been described elsewhere.1-4 The distortion of cement kilns has been discussed in a general manner by Rochow,6 ho indicates the amount of distortion which may occur in an unlined shell, and by Rosenblad: who states that the deformations of the shell are greatest above the trunnions. The present article indicates the extent of the distortion of a kiln to an oval shape in certain selected positions and the deviation from a straight line of the kiln along its length between two supports. The cement kiln is a long, hollow, rotating cylinder consisting of steel plates which may be either welded or riveted together. This shell is supported on tires, frequently 60 ft apart, which roll on trunnions. The large mass of the kiln causes distortion of its cross-section; it becomes slightly oval, i.e., diameters lengthen as they become horizontal and shorten as they become vertical. There is also a tendency for the shell to bow between supporting tires; this bowing may be upwards or downwards depending on the position of the weight forces and the supports. The extent of the deviations from the ideal kiln shape was investigated. Observations described in this paper were made on the shell of the clinkering zone between the first and second tires of two of the kilns at the Geelong works of Australian Portland Cement Pty. Ltd. The kilns were both 400 ft long and 10 ft diam with a welded enlarged burning zone 11 ft 6 in. diam. The shell was fabricated from mild steel and in this section its thickness was 1 in. It was lined with 41/2 in. of chemically bonded magnesite-chrome bricks which were jointed with mild steel plates. The kilns operate on a 4 pct slope and the speed may be varied between 0.75 and 1.68 rpm. The wet process is used; kilns are coal fired and are fitted with integral coolers. Temperatures within the kiln are difficult to determine with any accuracy because of the absence of black body conditions, but surface temperatures are probably in the range 1420° to 1470°C. Average shell .temperatures at the two positions at which the deformation studies were made were 370°C and 355"C respectively. Methods: In determining the ellipticity it was necessary to measure the lengths of the vertical and horizontal diameters while the kiln was in operation; data obtained from a stationary kiln would not have the same practical significance. For this purpose the four points V, W, X, and Y at the ends of two mutually perpendicular diameters were marked on one kiln. The point X is shown in Fig. 1. For the measurement of the length of the vertical diameter a vertical column, to which a horizontally aligned telescope was attached, was placed 10 ft from the kiln. The telescope could be racked up and down in a vertical plane. Two sets of readings were taken, one set when each of the points V, W, X, and Y was at its maximum height above the

Jan 1, 1957

By R. J. Allio, C. H. Randall

An automatic system for the quantitative analysis of microstrulcture has been developed. The method is based upon a statistical model of microstructure and employs phase intercept fractions as fundamental random variables. Structure-sensitive properties can be related explicitly to parameters derived from the distribution of phase intercept fractions in a matevial. THE properties of mechanical dispersions and of multiphase alloys art: intimately related to the amount, distribution, and intrinsic properties of the dispersed material. In many instances, the amount and distribution of the dispersed substances have greater influence on the over-all system properties than do the properties of the dispersed substance-Such properties as average particle size, particle size distribution, homogeneity of dispersion, volume per cent of dispersed phase, and mean free path between dispersed particles thus become critical in any evaluation of the properties of a dispersion. Unfortunately, techniques for evaluating quantitatively the microstructural characteristics of dis~ersions rapidly and accurately have not been available. If necessary, qualitative or semiquantitative devices can be utilized. Some such devices are based merely upon comparison of the specimens in question with arbitrary standards. Other techniques involve superposition of grids and tabulation of particles observed in different portions of the grid. Still other methods based upon lineal analysis entail counting lines or points at random upon the specimen to be examined; the number of intersections of the line with a given phase, the proportion of line or number of points which are covered by given phase are variously recorded. The mathematical basis for most of the techniques of quantitative metallography have been amply reviewed in the literature.'l2 without exctption, however, the standard techniques for quantitative metallography are either imprecise or are exceedingly tedious to apply. For example, tranverse integrating stage for rapid manual areal fraction measurement has been designed by Smith.3 Howerer, as in the case of any device based upon visual eslimation, operator bias may cause appreciable error. Various flying spot devices, on the other hand register particle size distributions in 2-dimensions, from which it is difficult to derive other properties of the dispersion. Thus, e.g., the 3-dimensional distribution cannot be inferred unless certain rather broad assumptions are made concerning the randomness of distribution and geometrical configuration of dispersed phase. Many limitations to the application of quantitative structural analysis can be overcome by the use of the microdensitometer, which is essentially an automated areal analysis device. Data obtained in the form of a distribution of phase intercept values are

Jan 1, 1962

By D. M. Hausen

This study identifies and describes various crystalline phases of the V205-Na20 system, and relates their properties to metallurgical aspects of vanadium production. Phase equilibria and stability ranges of sodium vanadate phases of varying molar ratios of Na20/V205 were investigated in a variety of plant products, ranging from fused "black cakes" (V20 melts) to "salt roast" calcines. Crystalline compounds, Including vanadium pentoxide, V205; sodium vanadyl vanadate, 6 phase, Na2O.V2O5.5V2O5; sodium vanadyl vanadate, y phase, 5Na20.V204.12V205; sodium metavanadate, Na20 .V 05; sodium pyrovanadate , 2Na20 .V205; and sodium orthovanadate, 4Na20.~2~5, have been characterized with the aid of X-ray diffraction patterns, infrared spectra, and optical properties in addition to chemical analyses, as a guide to mineralogical "troubleshooting" of plant problems and processes in vanadium pyro- and hydrometallurgy.

Jan 1, 1984

THE papers by G. F. Loughlin and I. A. Ettlinger discussed the distribution of formations and ore-bodies in two of the main mining districts of the Southwest. The convergence of the deeper orebodies at Cripple Creek points to their common hypogene ori-gin, as do the occurrences of the copper ores of, central Arizona. E. L. Bruce described the areas in southwestern On-tario around Red Lake and Woman Lake, another prom-ising gold district. Of special interest was a series of lantern slides showing the use of power-driven boats and of hydroplanes as means of transportation. Within a few years, no doubt; such devices will revolutionize the mining industry and reconnaissance mapping in these relatively inaccessible areas. Much interest was evinced in the paper by J. W. Finch on "Sedimentary Metalliferous Deposits of the Red Beds." It was written as a caution to people at-tempting to mine these deposits. The discussion of the chemical equations presented in the paper brought out the fact that a large amount of study of such ores is necessary before we shall be able to write equations to explain their formation. Especially pertinent were the discussions by David White as to the relation of decay-ing plant tissue to metalliferous deposits and the color of sediments; also the point brought out by T. S. Lover-ing that chemical compounds produced by bacteria may greatly affect the deposition and reorganization of sedi-mentary metalliferous deposits.

Jan 3, 1928

By A. L. Baxley

An Untapped Energy Resource As much as 20 billion cubic feet of natural gas per day are flared from remote oil fields for lack of a commercially viable means of capturing, transporting, and marketing such gas. The magnitude of these gas flares can be put into perspective from an early satellite photograph (Fig. 1) which shows lights from the major cities of Russia and Eastern Europe dwarfed by the natural gas being flared in the Persian Gulf. Together, these wasted resources contain the energy equivalent of about one-half of the gasoline consumption in the United States today (Fig. 2). Additional trillions of cubic feet of natural gas are "shut-in" because of no economically viable means of commercial recovery. Methanol and liquified natural gas (LNG) are the only two practical fuel products which can be produced economically from these gas supplies. Many of these gas supplies are less than 500 million cubic feet of gas per day, making an LNG facility uneconomic. In contrast, barge-mounted methanol plants can economically convert billions of cubic feet of gas per day into safe, clean-burning methanol. The methanol approach offers the only economical route to transform vast, known reserves of natural gas into a highly versatile primary liquid fuel. Methanol Barges: An Innovative Solution The barges will be towed to suitable offshore and upriver locations such as Alaska, South America, Africa, Southeast Asia, Australia, New Zealand, and the South Pacific Islands, as well as fields in the Persian Gulf and Mediterranean Sea. At the offshore production site, a barge will be anchored by a single point mooring buoy that will also serve as an entry point for natural gas feedstock and an offloading point for methanol (Fig. 3). At some sites the barge would be beached. Each barge will produce methanol and store it in internal tanks with a capacity of 18 million gallons. The methanol will be offloaded into conventional tankers and safely transported directly to market. Unlike LNG, methanol requires neither specially built carriers nor specially built receiving terminals. Once a particular gas field has been exhausted, the barge will be towed to another location to continue production. Each barge will measure 320 by 500 ft, approximately the size of four football fields, and will have the capacity to produce 1 million gallons or 2800 metric tons of methanol per day, from approximately 100 million cubic feet of natural gas per day (Fig. 4). The barges will use the highly successful "low- pressure" design developed by the Lurgi Company of Germany, a process proven in land-based methanol plants throughout the world during the last ten years. The decision to use Lurgi technology for "sea-trans- portable" methanol plants was based on the higher efficiency and greater operability of the technology compared to other commercially proven processes. The conversion plant will be designed to accept a wide variety of feed gas compositions, and will produce chemical-grade methanol for the broadest market base (Fig. 5). To minimize costs and construction time, the barge-mounted plants will be built in the high technology environment of a domestic or foreign shipyard. Selection of the construction site for each barge will be dictated by the location of the production site and by the relative construction costs. A number of shipyards have the capacity to build several barges per year. The detailed marine engineering to integrate the design of the processing plant with the floating platform can be performed by numerous major engineering companies around the world. Production Economics The barge-mounted plant concept not only assures large volumes of methanol, but it also keeps the overall production cost low by minimizing construction cost and providing access to low cost natural gas feedstock with no alternative or a negative value. Together, these advantages make the barge-mounted methanol plants economical today. The cost structure of a new barge-mounted methanol plant differs from that of existing methanol producers around the world (Fig. 6). For example, if a U.S. Gulf Coast producer is paying $4.70/MMBtu in 1985 for natural gas, the barge plant could afford to pay about $1.6O/MMBtu for gas and be able to deliver methanol to the Gulf Coast at the same price. At some future date such as 1990, a gas cost of $6.70/MMBtu for a domestic producer would have cost parity with about $3.60/MMBtu gas cost for the barge plant. In many foreign markets, feedstocks other than natural gas are used for methanol production (Fig. 7). For example, most of Japan's capacity is based on LNG while Western Europe uses residual oil or naptha. Because these feedstocks are substantially more ex- pensive than natural gas used by U.S. producers, the barge plants will compete even more favorably in these foreign markets. As crude oil prices rise, the value of methanol in each of these markets will increase. However, the hierarchy of methanol values in these markets should remain unchanged. Furthermore, the cost advantage for using methanol in these markets will improve as world energy costs increase since the value of remote gas should not escalate significantly.

Jan 1, 1982

By L. C. Brown, J. S. Kirkaldy

AS part of a program to investigate the diffusive properties of dilute ternary austenites, we have made a determination of the effects of cobalt on the activity of carbon in y iron. Samples of pure iron and Fe-Co alloys were equilibrated at 1000°C in controlled CO-C02 atmospheres, following the procedure of R. P. smith.' The 0.010-in.-thick samples were analyzed for carbon by microcombustion analysis2 to give a set of isoactivity curves. The latter were converted to activity-coefficient (standard state at infinite dilution) plots by combination with Smith's data' for the activity of carbon in pure iron measured in a CO-C02 mixture. Table I shows the composition of the base alloys used, while Fig. 1 shows the experimental results superimposed on a set of curves generated by the relation In the notation of Wagner,' the interaction parameter is the second coefficient on the right, Eq. [I] adequately correlates the experimental points for those alloys which were prepared from electrolytic iron by arc-melting (2,4, and 7 pct Co). The results for the 10 pct Co alloy (supplied by Crucible Steel Co.) do not correlate with the others. In fact, the experimental points for this alloy correspond to an interaction parameter of It is possible that the interaction parameter is a function of concentration for large cobalt additions, but we are inclined to attribute the discrepancy to the presence of a significant amount of aluminum added to this alloy for deoxidation purposes (Table I). Preliminary measurements for the system Fe-C-A1 have indicated an interaction parameter of Which implies that the effect of aluminum in solution on the carbon activity is sixty times greater than the effect of an equal weight percentage of cobalt. These observations cast some doubt on the precision of the results of Chandhok, Hirth, and Dulis who used this same 10 pct alloy for their experiments, obtaining an interaction parameter of E = 2.2. There is considerable doubt as to the activity of a plane Fe-C system. Using a CH4-Ha mixture, Smith obtains cg = 6.1 for the effect of carbon on the activity of carbon in austenite, rather than the value of 8.9 given in Eq. [I]. The use of CHa-Ha mixtures has recently been questioned by Kaufman, Radcliff, and cohens who state that there is some possibility that other hydrocarbons are formed. Fortunately, the determination of the interaction parameter is not sensitive to the coefficient of Nc. For example, using the CHI-H2 results we obtain a value which is almost the same as that obtained using the CO-CO, results. The authors wish to thank Mr. E. J. Dulis of the Crucible Steel Co. of America for supplying us with samples of the 10 pct Co alloy used in their original work. Financial assistance from the American Iron and Steel Institute is gratefully acknowledged.

Jan 1, 1963

By W. A. Olds, H. F. Yancey, M. R. Greer

John Griffen (Consulting Engineer, Pittsburgh)— This paper presents much data offering tentative answers to many technical questions that have been raised by the employment of dense-medium processes and, particularly. by use of the drum-type vessel. It is to be hoped that the Bureau of Mines will publish complete detailed data for the 50 or more tests so that it may be studied and analyzed by everyone interested. Such study will take considerable time and effort. The writer is therefore obliged to confine his discussion to a few points he has noted as being open to question. The data in Table VI which shows the recovery efficiency for the 1 to ½-in. fraction as 100 pct raised a question concerning the accuracy of these calculated figures; washability data on the washed coal and refuse show that such a figure is impossible. When the ash content of the misplaced material in the washed coal is higher than that of the misplaced material in the refuse, recovery efficiency must be less than 100 pct. A etudy of the data In Tables 111, IV, V, and VI suggest that this error probably arose from slight errors in calculating the data in Table V and more probably from the small scale used in plotting the washability curves from the Table V data. Using the size consist data and the weight and ash percentages of individual gravity fractions of each size as given in Tables 111 and IV and the reported recovery of 80 pct of washed coal, a revised Table V was calculated, carrying weight and ash percentages to hundredths of a percent instead of rounding off at tenths. This washability data for each size of Belling-ham reconstituted feed was then plotted on large scale washability curves. From this data the new Table XIV was prepared, which agrees very closely with data shown in Table VI except for two important values, theoretical yields and recovery efficiencies. As will be noted the recovery efficiencies in Table XIV are significantly lower than those given in Table VI. A study was then made of the data showing distribution of the specific gravity fractions to washed coal and refuse. This study indicated that when this distribution was based on the fractions as tested at 0.1-sp gr intervals the number of points obtained were insufficient to establish the distribution curves with reasonable precision, which in turn would affect the accuracy of the values for the specific gravity of separation and the error areas. The data in Tables III and IV of the paper and curves prepared therefrom make it possible for the specific gravity fractions to be subdivided further. This was done using 0.05-sp gr fractions and the distribution data so obtained is given in Table XIV, with resulting values for the specific gravity of separation and the error areas. The writer believes that the derived values shown on Table XIV are more accurate than the correspond-

Jan 1, 1955

By Larry Kaufman

A useful method for estimating the entropy of NaCl type compounds has been developed by combining the Debye theory of specific heat with the Lindemann formula. This method pemnits calculation of the entropy from a knowledge of the atomic weight, atomic volume, and melting point of the compound. Comparison of the calculated and observed entropies of 35 NaCl type compounds over a wide temperature range yields good agreement thus establishing the usefulness of the method. Application of the method to other crystal types is also discussed. KUBASCHEWSKI~ has suggested a useful method of estimating the enthalpy of formation of inter-metallic compounds from a knowledge of the crystal structure, lattice parameter, and heats of sublimation of the component elements. This method is quite valuable in predicting the tendency for compound formation in a given system and is of particular value in considering systems for which no experimental data are available. In order to supplement the enthalpy calculation afforded by Kubschewski's method, it would be of value to be able to estimate the entropy of compounds so that the entropy and free energy of formation could be evaluated. Although a considerable body of such data determined by calorimetric and equilibration techniques exists at present, the difficulty of making such measurements (particularly at high temperatures) and the ever increasing number of new compounds which are of interest make the desirability of such a computational method clear. This paper deals with a method for calculating the entropy of a compound from a knowledge of the atomic weight, atomic volume, and melting point. Since these data are generally easier to determine and therefore more readily available than thermo-dynamic data, they should provide an additional tool in estimating the stability and reactivity of compounds at high temperatures. I) THE ENTROPY OF PURE METALS As a first approximation, the specific heat of a pure metal can be represented by a sum of terms where C,($/tI is the vibrational specific heat calculated on the basis of the Debye theory, lo4 TC, (0/T) is an approximation to the Cp - C, correction. T is the electronic specific heat, and Cp (p) is the magnetic specific heat. Although the Debye theory does not provide a complete description of the vibrational specific heat, i.e., the Debye temperature 0 is not a constant, it does provide a good approximation when used properly. Blackman6'7 has written several reviews on this subject discussing the different values of 0 determined by various methods (specific heat, X-rays, elastic constants, electrical resistivity, and so forth), as well as the observed temperature dependence of 0 with T. In the present case the 0 in Eq. [I] naturally refers to the specific heat 0. The variation of Debye 0 (as determined from specific heat measurements) with temperature is observed to exhibit its most radical behavior at very low temperatures. At higher temperatures the 8 values are observed to become more nearly constant. Blackman6'7 has presented the variation of 0 with temperature for several metals. His tabulation is reproduced in Table I. Reference to Table I shows that above a certain temperature level, 0 remains fairly constant. The value of 0 which is most useful in computing the specific heat, and hence the entropy, is the value of 0 in the range 0/6 « T « 0. In 1910, Lindemann' suggested a relation for estimating Debye 0 values. According to this formula, where V is the atomic volume, T is the melting point in 'K, M is the atomic weight, and CL is a constant. Mott and Jones9 present this formula and state that there is at present no satisfactory theoretical explanation, but that it does have an empirical basis. By using the valuesof 0 in Table I along with known1' values of M, T, and the molar volume VM, where the Lindemann constant can be evaluated. This

Jan 1, 1962

By H. W. Turner

Lying to the east of the Rio Grande, in central New Mexico, is a long N. and S. mountain range, broken into separate ridges at several points. These have received separate names; the mountains at the south end, near El Paso, being known as the Franklin mountains, and then, following successively, to the north, the San Andreas range, Sierra Oscura, Manzano and Sandia mountains. At the eastern base of the Sierra Oscura there are several low ridges, remarkable for their red color. All of these red ridges contain reefs of copper-ore. The eastern flanks of the Sierra Oscura are composed of limestone. Some fossils in the limestone were examined by Prof. J. P. Smith of Stanford University, who says they are Fusulina and indicate an Tipper Carboniferous age. The sandstones and shales containing the copper-reefs directly overlie this limestone (Fig. I), and are very likely of Permian age, like the similar beds in Texas, described by Mr. W. F. Cummins.* Overlying the copper-beds are red sandstones and shales in which very little copper has been found. The cupriferous zone and the red sandstones and shales are everywhere associated, and as one stands on a high point, he will see that these rocks form three main belts or lines of hills. These may be referred to as the northern, middle and southern belts. The northern belt was not visited by me, but is known to contain copper-deposits. The middle belt has a trend of N. of W. and S. of E. The copper-reefs have been traced for a distance of more than 2 miles. The southern belt has a trend of about N. 30' W. and S. 30°

Jan 1, 1903

By L. J. Boucher

The beneficiation process at Northampton is described and reasons are given for installing a flotation plant. The economics of running the plant, the difficulties of operation, and subsequent remedial action are discussed. CEMENT rock from a quarry operated by the Northampton plant1, 2 of the Universal Atlas Cement Co. has a relatively low average CaCO³ content. To meet specifications required for cement manufacture it was formerly necessary, over succeeding years, to add increasingly larger amounts of high-lime, low-alumina rock, which was obtained from a quarry operated by the company at a point along the New Jersey-New York state border, 79 miles from Northampton. Previous to 1940, 8 pct of total kiln feed consisted of high-lime rock. From 1940 to 1943, this figure jumped to 13 pct. Today it would be necessary to use 18 pct of this high-lime to meet current specifications. Increasing transportation costs made this an expensive operation. In addition, this high-lime rock quarry was contaminated with granite and high magnesia pockets. As there was no available high-lime rock in the Lehigh Valley, it was decided in 1936 to install a pilot plant where experimental work was done on processing local cement rock with flotation and burning the resulting product in a small kiln. This plant was in operation for six months and at the end of that period a suitable method of flotation had been established. From these studies it was also found that if the proportion of shipped-in rock rose slightly above 10 pct it became economically advisable to use the flotation process. It is the object of this paper to present briefly the operation of the flotation system at the Northampton plant. It seems advisable to comment on the raw material used in this process. The Northampton quarry lies geologically in what is known as the Jacksonburg formation of Trenton limestone.' In Pennsylvania this extends in a southwesterly direction from Portland, through Nazareth, Bath, and Northampton and across the Lehigh River to Ormrod. This argillaceous limestone was formed from marine deposits laid down during the early Ordivician period when a shallow sea covered most of Pennsylvania. Carbonaceous matter in the original deposit formed graphitic carbon under later metamorphic forces. From this graphite the cement rock of the Lehigh Valley derives its dark color. Most of the graphite must be removed before lime flotation can proceed. The quartz in this rock is desirable from the chemist's point of view, as it furnishes him with a form of silica necessary in the calcining process, but its abrasive properties damage pumps and piping. Aluminum silicates of potassium, sodium, iron, and magnesium are found in the form of sericite. Cal-cite averages from 69 to 76 pct. Iron in the form of iron pyrites is also present and has no deleterious effect. Talc is present in minute quantities. The

Jan 1, 1954

By E. A. G. Colls

IN all branches of the chemical industry, corrosion plays a very costly part unless it is suitably com-batted, and as a result it is probably correct that chemical and design engineers are more corrosion conscious in the field of chemical industry than in others. Most metals occur in nature in combination with other elements. The refined or reduced state to which man converts them for his use, by removing the combining elements, leaves them in an unstable condition. Therefore in most of the media to which the metals are exposed they are constantly combining with the constituents of their environment, or in other words they are continually being corroded. Similarly, nonmetallic materials are corroded by undergoing chemical change. The rate at which corrosion takes place varies widely from metal to metal and medium to medium. In practically all cases the corrosion of metals in solutions (electrolytes) is electrolytic in nature and the rate of corrosion is dependent on many factors such as temperature, pressure, internal stresses, galvanic action, metal-ion concentration, and so on. In the chemical industry substances must be handled which are particularly corrosive to materials of construction. At the chemical plants of The Consolidated Mining and Smelting Co. of Canada, Ltd. (otherwise known as Cominco), situated at Trail, B. C., Canada, the following are some of the materials that have to be handled: Gases. Sulphur dioxide, sulphur trioxide, carbon dioxide, carbon monoxide, oxygen, hydrogen fluoride, ammonia, hydrogen sulphide, and oxides of nitrogen. Liquids. Solutions of ammonium sulphate, ammonium sulphite, ammonium nitrate, caustic soda and potash, sulphuric acid, nitric acid, hydrofluo-silicic acid, hydrofluoric acid, phosphoric acid, aqua ammonia, and formic acid. Solids. Gypsum (containing phosphoric acid), ammonium sulphate, ammonium nitrate, phosphate rock, caustic soda, potash, and phosphate fertilizers.

Jan 1, 1951

By E. A. G. Colls

IN all branches of the chemical industry, corrosion plays a very costly part unless it is suitably com-batted, and as a result it is probably correct that chemical and design engineers are more corrosion conscious in the field of chemical industry than in others. Most metals occur in nature in combination with other elements. The refined or reduced state to which man converts them for his use, by removing the combining elements, leaves them in an unstable condition. Therefore in most of the media to which the metals are exposed they are constantly combining with the constituents of their environment, or in other words they are continually being corroded. Similarly, nonmetallic materials are corroded by undergoing chemical change. The rate at which corrosion takes place varies widely from metal to metal and medium to medium. In practically all cases the corrosion of metals in solutions (electrolytes) is electrolytic in nature and the rate of corrosion is dependent on many factors such as temperature, pressure, internal stresses, galvanic action, metal-ion concentration, and so on. In the chemical industry substances must be handled which are particularly corrosive to materials of construction. At the chemical plants of The Consolidated Mining and Smelting Co. of Canada, Ltd. (otherwise known as Cominco), situated at Trail, B. C., Canada, the following are some of the materials that have to be handled: Gases. Sulphur dioxide, sulphur trioxide, carbon dioxide, carbon monoxide, oxygen, hydrogen fluoride, ammonia, hydrogen sulphide, and oxides of nitrogen. Liquids. Solutions of ammonium sulphate, ammonium sulphite, ammonium nitrate, caustic soda and potash, sulphuric acid, nitric acid, hydrofluo-silicic acid, hydrofluoric acid, phosphoric acid, aqua ammonia, and formic acid. Solids. Gypsum (containing phosphoric acid), ammonium sulphate, ammonium nitrate, phosphate rock, caustic soda, potash, and phosphate fertilizers.

Jan 1, 1951

By Milton E. Wadsworth

INTRODUCTION The purposes of this conference are aimed mainly at the treatment of fine or ultra fine particles in terms of beneficiation and chemical processing of minerals. For this reason the discussion on leaching will be confined to processes which treat slurries rather than those which treat a large variety of low and medium grade materials by vat leaching or dump leaching techniques. This eliminates such hydro-metallurgical systems as solution mining from consideration. This discussion will focus predominantly upon the behavior of fine particles as associated with their chemistry in leach reactors. Four major sub-headings may be pointed to as encompassing the major areas in which research and engineering design activity should be directed. These are: 1) generation of fine particles, 2) heterogeneous kinetics of leaching, 3) solution chemistry, 4) engineering design and control of flow reactors. Each of these topics will be addressed briefly in this presentation to illustrate current developments and future needs. GENERATION OF FINE PARTICLES As will be pointed out more quantitatively in the next section the generation of fine particles has great influence upon leaching systems inasmuch as in most cases the rate of leaching is related to the surface area of the particles involved. This is true for acid or base leaching of oxide minerals as well as a large variety of sulfides which have been considered in commercial processes and which have in the case of copper received increased attention during the past decade. Mean particle sizes of slurries vary broadly depending upon the type of grinding equipment being used. For example, in the agitation leaching of uranium ore the slurry typically consists of particles approx-

Jan 1, 1979