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By Tracy C. Jarrett

In making gold alloys possessing certain physical properties, such i~nportant factors as corrosion resistance, color, hardness and melting points must be considered. All of these requirements depend directly upon the composition. It is possible to obtain the same colored gold alloy by using different compositions, but in doing so one may bring in some undesirable property. Other investigations have been carried on in this field by F. E. Carter,' E. M. Wise12 and L. Sterner-Rainer2 To make a complete study of the effect of composition upon these properties, a systematic investigation was carried on involving a range of copper content from 85 to 65 per cent. Elements such as zinc, silver and nickel were used to replace in part the copper content. The gold content in all the alloys remained constant. Only 10-karat gold alloys of those containing 41.6 per cent gold will be considered. All of the alloys were made in an induction furnace. Each alloy was cast in a 3 by 1/4 by 3/4-in. ingot. The method of obtaining the melting points and making color determinations was described in a previots paper.4 The Rockwell B scale with the 1/16-in. ball and 100-kg. weight was used for all hardness determinations. The submersion of test pieces in concentrated nitric acid is one of the standard corrosion tests used in the optical trade. A test piece in the 50 per cent cold-worked condition, % by 2 by 0.045 in., is blanked from a skip using a die, and the weight loss per square inch of surface is taken as a means of comparison. The time for this test is 2 1/2 hr. of actual submersion of the test picce in the acid. This standard test was applied to all of the 10-karat gold alloys discussed in this paper. The tensile tests were made upon strips of the dimensions shown in Fig. 1. The test pieces after blanking were annealed at 1300" F. for 20 min. and cooled in air. Thc "drop of the beam" method was used in determining the yield point, as there was a very marked "drop" when the yield point was reached.

Jan 1, 1940

By Tracy C. Jarrett

In making gold alloys possessing certain physical properties, such i~nportant factors as corrosion resistance, color, hardness and melting points must be considered. All of these requirements depend directly upon the composition. It is possible to obtain the same colored gold alloy by using different compositions, but in doing so one may bring in some undesirable property. Other investigations have been carried on in this field by F. E. Carter,' E. M. Wise12 and L. Sterner-Rainer2 To make a complete study of the effect of composition upon these properties, a systematic investigation was carried on involving a range of copper content from 85 to 65 per cent. Elements such as zinc, silver and nickel were used to replace in part the copper content. The gold content in all the alloys remained constant. Only 10-karat gold alloys of those containing 41.6 per cent gold will be considered. All of the alloys were made in an induction furnace. Each alloy was cast in a 3 by 1/4 by 3/4-in. ingot. The method of obtaining the melting points and making color determinations was described in a previots paper.4 The Rockwell B scale with the 1/16-in. ball and 100-kg. weight was used for all hardness determinations. The submersion of test pieces in concentrated nitric acid is one of the standard corrosion tests used in the optical trade. A test piece in the 50 per cent cold-worked condition, % by 2 by 0.045 in., is blanked from a skip using a die, and the weight loss per square inch of surface is taken as a means of comparison. The time for this test is 2 1/2 hr. of actual submersion of the test picce in the acid. This standard test was applied to all of the 10-karat gold alloys discussed in this paper. The tensile tests were made upon strips of the dimensions shown in Fig. 1. The test pieces after blanking were annealed at 1300" F. for 20 min. and cooled in air. Thc "drop of the beam" method was used in determining the yield point, as there was a very marked "drop" when the yield point was reached.

Jan 1, 1940

By Clyde E. Williams

Estimates indicate a life of known Lake Superior iron ore reserves of 20 to 30 years. Although some believe the future ore supply will come from foreign sources and will be brought to interior points via the projected Great Lakes-St. Lawrence waterway, and others fear a displacement of the interior steel-producing districts to the Atlantic seaboard, the author has faith that American engineering skill will make possible the use of lean ores from the Lake Superior district. Three general types of Lake Superior ores and ore formations, that represent possible reserves and require beneficiation, are: (1) the wash ores of the western Mesabi range, (2) the partly leached hematitic formations, and (3) the oxidized but largely unleached iron formations. The total tonnage represented by (1) and (2) is not large, but the recovery of iron from present washery tailings would bring on the market the equivalent of nearly one million tons of wash ore, annually. Group 3 comprises the magnetic iron formation of the eastern Mesabi range, the hematitic formations including the taconites of the Mesabi range, and the iron formations of all the other ranges. These formations represent our future supply of iron ore. Their treatment requires intensive research because the bulk of the iron oxide and silica minerals exist in a finely disseminated condition. The possibilities of the adaptation of tables, oil flotation, and other processes warrant extensive study. Cheaper method of agglomeration of the concentrate is essential. Recent developments in better preparation and sizing of blast-furnace charges indicate that substitution of agglomerated ore for fines will increase furnace efficiency and output. If agglomerated beneficiated ore can be shown to rate a per-unit premium for iron contents over the base rate or a premium for structure, the payment of these would greatly assist in enlarging our iron ore supply. Since present methods of taxation of ore reserves, which encourage the rapid depletion of rich ores, will result in using up our rich ores and later on putting domestic producers at a disadvantage in competing with' foreign producers, it would seem highly provident to conserve our rich ores and to increase the use of beneficiated ores as soon as possible.

Jan 1, 1931

By S. LeFevre

, The solution of the housing and sanitation problem in mining communities, keeping in view both economic and humanitarian aspects, demands the best thought of the management of such enterprises. Upon the solution depend the health and comfort of the employee and his family, and as a consequence his contentment and efficiency. The following description covcrs briefly the methods installed for Witherbee, Sherman & Co. The operation of the system has been for about two years under the direct supervision of T. A. Hammond, Land Agent, and I am indebted to him for a compilation of the results. Sanitation The sanitary service covers 238 tenements. The installation cost was about $22 per tenement, as follows: Privy, $15; privy box, $3; proportion of incinerator cost, $2; garbage can, $2. The operating cost is $1 per month for each tenement. In considering the installation of an ordinary village system of water supply and sewerage two difficulties were encountered: First, lack of a sufficient quantity of water; there is no stream large enough, as Mineville is situated very close to the divide between the Lake Champlain and Hudson River watersheds. A storage reservoir was tried, but the only location available, among glacial hills, would not hold water. Second, the expense of digging ditches for the distribution of water and sewer pipes is so great as to be prohibitive; Mineville is built chiefly in a valley covered in the bottom with drift, in this case a combination of boulders and hard pan. Digging in this material costs 80c. to $1 per cubic yard, and pipes must be placed 41/2 ft. down to be below frost. The houses are scattered along 4 miles of streets, the oldest having been built in the original forest 65 years ago. The newer houses have gone up a few at a time wherevcr a clear space could be found and the slopes were not too steep. This has advantages, as it separates the dwellings into

Jan 1, 1915

The Telfer Project, one of the world's newest gold mines, is located about 300 km (190 miles) northeast of the Mt. Newman iron ore project in the northern part of Western Australia. The first mineral claims were staked in 1972; and by mid-1975 ore reserves of 3. 8 million mt (4. 19 million st) of 9.6 g per mt (0. 28 oz per st) ore had been indicated. It is interesting to note that Newmont spent more than 10 years and A$10 million in Australia for extensive mineral exploration before finding the Telfer deposit, and then spent approximately A$3 million in exploration and feasibility engineering on Telfer. Including this A$3 million, a total of A$27 million was spent to complete construction of the mine, village, gold treatment plant and associated roads, airport, water and services. Over 50% of the capital cost is in the metallurgical facility, or approximately A$10, 000 per ton per day. All economically significant gold mineralization at Telfer occurs in a series of layered quartz-limonite reefs in which the former pyrite has been oxidized to limonite to a depth of 100 m (330 ft). The most important gold reef occurs at the base of the siltstone-shale horizon within the enclosing sandstone dome -like structure. At the Main Dome structure the dipping ore horizons will be mined to a vertical depth of about 60 m (200 ft) by open-cut methods. The waste-to-ore ratio is approximately 12:1. Eventually 44 million mt (48. 5 million st) of ore and waste will be mined. Mining of the waste is by contract; however, the ore and a thin layer of waste is company-mined. Dilution from mining the geological ore reserve is about 10%. The ore is completely oxidized and the gold occurs free within the reef, material as discrete particles of varying but mainly fine grain size. Most of the gold is "free milling"; that is, over 50% of the gold is coarse enough to be recoverable by gravity concentration. Two duplex mineral jigs receive the two cyclone underflows from the grinding circuit. The rougher jig concentrate is up-graded on a continuous strake from which the concentrate is tabled to produce a final free gold product. Jig tailings are returned to the ball mill and the concentrates are amalgamated. Gold amalgam is pressed, retorted, and melted into gold bars. The gravity gold recovery circuit is the same as was used in many of the gold mills in California in the 1930s.

Jan 1, 1981

By Reno H. Sales, Charles Meyer

AT Butte, successive zones of sericitized and argillized quartz monzonite occur around every ore-bearing fracture regardless of its size, attitude, or relative age. The two types of alteration always occupy the same relative positions; sericite adjacent to the ore-bearing vein, clay minerals always between the scricitized rock and fresh quartz monzonite, except where overlap of alteration effects between adjacent fissures has eliminated the lower grade mineralogical products, as is the case in much of Butte's Central zone of pervasive sericitization. As long as active circulation continued in the channel, each zone migrated away from the fissure, that is, it grew at its outer edge and simultaneously receded at its veinward edge because of encroachment by the next innermost zone. The different mineralogical and chemical responses within the wall rocks to the attack by the ore fluid are dependent not on a drastic about-face change of composition of the fluid in the channel relative to its ability to alter the quartz monzonite but on continuously varying conditions of physico-chemical environment within the wall rock outwardly from the vein.' Introduction From the economic viewpoint it is highly desirable that much effort be expended for the purpose of increasing our knowledge of ores and their origin. It has been the observation of the senior writer, many times expressed, that the mining companies have spent too little money in research on the geology of nature's deposits of copper, lead, and zinc, which we know to be of limited extent and which, when exhausted, must be replaced by new discoveries. Experience at Butte and elsewhere has forced the conclusion that observation and mapping in the field must be supplemented by laboratory work if we are to arrive at a reasonably correct understanding of the geology of ore bodies and their environments. It is only through the medium of such correct understanding of geology that we shall be able to accomplish the maximum toward aiding mine operations and at the same time provide a proper background for field examination work whether it be geological or geophysical. The Anaconda Copper Mining Company's answer to the need above expressed has been to equip a geological laboratory at Butte. The reason why Butte was selected is obvious, for situated there is one of the world's largest and geologically most interesting concentrations of copper and zinc. Furthermore, because of the great extent of underground workings both laterally and vertically, the opportunities for observation and study of ore occurrences probably are unequaled anywhere. The laboratory was established with five principal objectives in view. These were: 1. As an aid to Anaconda Company mine operations at Butte and elsewhere, this work to supplement that of the mine geologists. 2. To aid in acquiring as complete an understanding as possible of the behavior of Butte veins and ore bodies laterally and in depth.

Jan 1, 1949

By Charles Meyer, Reno H. Sales

AT Butte, successive zones of sericitized and argillized quartz monzonite occur around every ore-bearing fracture regardless of its size, attitude, or relative age. The two types of alteration always occupy the same relative positions; sericite adjacent to the ore-bearing vein, clay minerals always between the scricitized rock and fresh quartz monzonite, except where overlap of alteration effects between adjacent fissures has eliminated the lower grade mineralogical products, as is the case in much of Butte's Central zone of pervasive sericitization. As long as active circulation continued in the channel, each zone migrated away from the fissure, that is, it grew at its outer edge and simultaneously receded at its veinward edge because of encroachment by the next innermost zone. The different mineralogical and chemical responses within the wall rocks to the attack by the ore fluid are dependent not on a drastic about-face change of composition of the fluid in the channel relative to its ability to alter the quartz monzonite but on continuously varying conditions of physico-chemical environment within the wall rock outwardly from the vein.' Introduction From the economic viewpoint it is highly desirable that much effort be expended for the purpose of increasing our knowledge of ores and their origin. It has been the observation of the senior writer, many times expressed, that the mining companies have spent too little money in research on the geology of nature's deposits of copper, lead, and zinc, which we know to be of limited extent and which, when exhausted, must be replaced by new discoveries. Experience at Butte and elsewhere has forced the conclusion that observation and mapping in the field must be supplemented by laboratory work if we are to arrive at a reasonably correct understanding of the geology of ore bodies and their environments. It is only through the medium of such correct understanding of geology that we shall be able to accomplish the maximum toward aiding mine operations and at the same time provide a proper background for field examination work whether it be geological or geophysical. The Anaconda Copper Mining Company's answer to the need above expressed has been to equip a geological laboratory at Butte. The reason why Butte was selected is obvious, for situated there is one of the world's largest and geologically most interesting concentrations of copper and zinc. Furthermore, because of the great extent of underground workings both laterally and vertically, the opportunities for observation and study of ore occurrences probably are unequaled anywhere. The laboratory was established with five principal objectives in view. These were: 1. As an aid to Anaconda Company mine operations at Butte and elsewhere, this work to supplement that of the mine geologists. 2. To aid in acquiring as complete an understanding as possible of the behavior of Butte veins and ore bodies laterally and in depth.

Jan 1, 1949

By I. N. Knapp

I Herewith present some notes on the use of Portland cement to cement in the casing, and for plugging, to exclude water from oil and gas wells, and the methods employed. I have used my best efforts to. make each step of the operation of cementing wells perfectly clear. The information is the result of actual experience and observation. The illustrations are from original drawings made especially for this paper. Portland Cement It is not necessary to discuss here the manufacture of cement. Any established brand of the slower setting Portland cements may be purchased with the confidence that it will harden, if properly used, and exclude water from and plug wells efficiently. Setting.—By the setting of cement is meant its initial change from a soft or plastic mortar to a friable solid. After the cement has become thoroughly set it is still very weak and can be readily pulverized in the fingers. Setting is thought to be effected by the crystallizing out of the silicate and the aluminate of lime, which are soluble in water in their anhydrous form. After dissolving in the water they pass to the hydrated state, in which they are insoluble, and hence are precipitated in a crystalline form. Ordinarily neat Portland cement mortar remains perfectly plastic for from 1 to 1 1/2 hr. after mixing with water at about 70" F. A higher temperature accelerates and a lower retards setting.. Hardening.—This is due to a continual crystallization of salts from solution, and to further chemical and physical changes which develop slowly, but which continue for long periods of time. Testing.—It is no more necessary for an operator to go into the scientific testing of cement to be used in a well than to so test the pipe used. He must depend for the quality of each on the tests and reliability of the manufacturer. Cement or pipe may be damaged in shipment so

Jan 1, 1915

By M. V. Lowry

This paper outlines the economic considerations that led to the recent installation of a thickener at St. Joseph LeadCo.'s Balmat, N.Y. mill. To incorporate storage of concentrates, they decided upon a single, unusually deep tank to be used for both storage and thickening. The abnormally high rake lift required was achieved by the novel feature of having the entire drive platform raise and lower. Initial operating problems are described along with the satisfactory solutions. Total costs for concentrate handling before and after installation of the storage thickeners are compared. In Northern New York State, the St. Joseph Lead Co. conducts a 2100 tpd zinc mining and milling operation at its Balmat Plant. Conventional crushing, grinding, and flotation is used to produce a zinc concentrate. For 32 years, from 1930 through 1962, the plant operated with the concentrates going directly from flotation to the filtering, drying, and loading facilities. All of the concentrate handling equipment, therefore, had to operate 24 hrs per day. It also had to accommodate wide fluctuations in tonnage, due to variations in the grade of ore. Many problems were thereby encountered in filtering and drying, but it was never concluded that the cost could be justified for installing a conventional, large diameter thickener. Finally, in 1963, they installed an unconventional thickener that is unusual in several respects. The tank depth is 16 ft instead of the normal 8 ft. The rakes are raised and lowered by having the main drive gear located on a movable platform. Automatic controls are programmed to raise the drive platform and rakes during one shift of storage. During the next two shifts of withdrawal, the controls are programmed to lower the drive platform and rakes. After three years of operating this unique storage-thickener, the conclusion is that a correct choice was made from several alternative schemes for storing concentrates. The various considerations involved in the final selection will here be analyzed, and the design features and installation details will be de- scribed. Operating problems and modifications made to the equipment will next be considered, and finally the effects upon filtering, drying, and loading will be reported. SELECTION CONSIDERATIONS Even without a thickener, concentrate handling had become reasonably efficient at the Balmat Mill by the year 1962. A tonnage that varied between 6 and 25 tph was being handled fairly satisfactorily. The filter cake moisture of 8%% seemed quite respectable, except that two large filters were usually in service. Three filters often had to be operated in order to prevent excessive filter overflow with consequent loss of values. This situation occurred when zinc concentrates from flotation exceeded 20 tph and when filter cloth blinding developed. Over the years, numerous small improvements had been effected, such as: selection of a filter cloth with better flow characteristics; addition of flocculant to the filter feed; and, in 1953, the smallest of three drum filters was replaced by a five disc, 8' 10" diam filter with a bottom agitator and snap blow. As another example of fairly efficient operation, the oil-fired dryer was doing a seemingly satisfactory job of further reducing the moisture content to an average of 3%. However, there were often considerable dust losses when the tonnage suddenly dropped off to 6 tph. At high tonnage rates, the resulting high moistures of 4% and 5% caused difficulties due to concentrates sticking and freezing in chutes leading to the box car loaders. (Drying of concentrates is justified because of the high freight rate for the long shipping distance to the company owned smelter at Josephtown, Pa. near Pittsburgh.) It was long realized that installation of a thickener would permit the subsequent steps of concentrate handling to proceed more smoothly and would alleviate the problems existing in the filtering, drying, and loading operations. It was also realized that even a slightly lower filter cake moisture could mean considerable savings in fuel oil. However, all these factors were never quite sufficient to warrant the expense of a thickener until three more considerations were added to the picture. First, the advent of flocculants meant that a thickener of relatively small area could now be considered. Secondly, a complete renovation of the zinc flotation circuit was made between 1957 and 1961. The

Jan 1, 1967

By D. Turnbull, R. E. Cech

EXPERIMENTAL studies of precipitation of iron from solid solution in copper by Gordon and Cohen 1, Bitter and Kaufmann 2 and Smith 3 revealed that the precipitate particles were initially paramagnetic but could be changed to a ferromagnetic

Jan 1, 1955

By Rudolf Gahl

THE history of flotation in America is very short, at least as far as the large-scale application of the process is concerned. It is remarkable how many important developments have taken place inn the last few years and are already being extensively utilized. What was new a year ago, seems almost commonplace now. For this reason it is with hesitation that I follow the suggestion: of Dr. Ricketts, President of the Institute, to describe the experiences of the Inspiration Consolidated Copper Co. with the flotation process. TESTS CONDUCTED IN SMALL TEST-MILL When the Inspiration company first decided to build a concentrating plant, nothing was known about flotation, and the process was to be gravity concentration pure and simple. Demonstration Tests Conducted by Minerals Separation Co. While plans were being prepared by H. Kenyon Burch (who had been intrusted with the design and construction of the concentrator) the Minerals Separation Co., a concern at that time little known in America, asked and obtained permission to demonstrate the value of its flotation process for Inspiration ore. As. a consequence, a small 50-ton flotation machine of standard design was added to the company's test plant and started to operate in the beginning of 1913. This marks the beginning of flotation at Inspiration. The results obtained with this machine, which was operated by members of the Minerals Separation staff, so far surpassed what this company anticipated that it was decided to continue flotation tests for this purpose, and two of the flotation experts of the Minerals Separation Co., I. L. Greninger and G. A. Chapman, were retained. L. R. Wallace, now superintendent of the Miami works of the International Smelting Co., was at that time metallurgist of the Inspiration company and in that capacity took an active part' in these tests. Great credit is due to him for his quick recognition of the possibilities of flotation.

Jan 9, 1916

By M. C. Dow

Belt conveyors generally are conceded to be the most economical method yet devised for the transportation of large quantities of bulk materials within plants. Belts are coming into greater use for transportation over long distances and are replacing other forms of long-haul conveyance. It is not the intent of the writer to comment on the design of belt conveyors, but to offer some suggestions for improvement in the operation of conveying belts, based on many years experience with belts in several stone-crushing plants. It is the contention of this writer that opportunities for improvement not fully realized by most operators exist in many plants and that a study of the individual conveyors can result in lower unit belt costs. General Reliability It is the fool-proof nature and general reliability of the belt conveyor that is responsible for its neglect. Even when abused, a belt will carry large tonnages and last a long time, often outlasting the personnel responsible for its care. Some operators look upon the purchase of a new belt as an expensive outlay every so many years, rather than a constant and steady cost amounting in belt wear alone to several dollars every operating day. This belt wear for all conveyors in one stone-crushing plant known by the writer costs 1 /12 cents per ton or $12 to $15 per hour, based on the present cost of belt replacements. The fact that these replacement costs are double those of prewar quality emphasizes the necessity of improving the conditions that make belts wear out. Some of those conditions are the responsibility of the conveyor designer, and if a serious original error has been made, this handicap cannot be overcome by the operator. If the belt is too narrow, too steep, or too fast for good loading, the operator finds that he has an inherently expensive belt. The other factors that decrease the life of a belt are more or less under his control. The two factors of most importance are the loading conditions and the alignment. Most of the cover wear and carcass cutting occurs at the loading point and if the alignment is not good under all conditions, edge wear or damage may result, Fig I. Loading the Belt It is difficult to load a belt in an ideal manner; that is, to flow the material on the moving belt at a steady rate, without impact, without turbulence, and with a velocity equal to and in the same direction as the belt. An inclined belt is especially difficult to load and particularly when its speed is over 300 or 350 fpm. Inclined conveyors require longer skirt plates to prevent spillage until the load settles. It does not seem reasonable to expect an inclined the to carry the same load as a horizontal belt of the same width and speed, because of the difficulty in loading

Jan 1, 1948

By M. C. Dow

Belt conveyors generally are conceded to be the most economical method yet devised for the transportation of large quantities of bulk materials within plants. Belts are coming into greater use for transportation over long distances and are replacing other forms of long-haul conveyance. It is not the intent of the writer to comment on the design of belt conveyors, but to offer some suggestions for improvement in the operation of conveying belts, based on many years experience with belts in several stone-crushing plants. It is the contention of this writer that opportunities for improvement not fully realized by most operators exist in many plants and that a study of the individual conveyors can result in lower unit belt costs. General Reliability It is the fool-proof nature and general reliability of the belt conveyor that is responsible for its neglect. Even when abused, a belt will carry large tonnages and last a long time, often outlasting the personnel responsible for its care. Some operators look upon the purchase of a new belt as an expensive outlay every so many years, rather than a constant and steady cost amounting in belt wear alone to several dollars every operating day. This belt wear for all conveyors in one stone-crushing plant known by the writer costs 1 /12 cents per ton or $12 to $15 per hour, based on the present cost of belt replacements. The fact that these replacement costs are double those of prewar quality emphasizes the necessity of improving the conditions that make belts wear out. Some of those conditions are the responsibility of the conveyor designer, and if a serious original error has been made, this handicap cannot be overcome by the operator. If the belt is too narrow, too steep, or too fast for good loading, the operator finds that he has an inherently expensive belt. The other factors that decrease the life of a belt are more or less under his control. The two factors of most importance are the loading conditions and the alignment. Most of the cover wear and carcass cutting occurs at the loading point and if the alignment is not good under all conditions, edge wear or damage may result, Fig I. Loading the Belt It is difficult to load a belt in an ideal manner; that is, to flow the material on the moving belt at a steady rate, without impact, without turbulence, and with a velocity equal to and in the same direction as the belt. An inclined belt is especially difficult to load and particularly when its speed is over 300 or 350 fpm. Inclined conveyors require longer skirt plates to prevent spillage until the load settles. It does not seem reasonable to expect an inclined the to carry the same load as a horizontal belt of the same width and speed, because of the difficulty in loading

Jan 1, 1948

By M. Cohen

THERE seems to be a natural urge for the human mind to wonder about the beginning of things. When an explosion occurs, we immediately inquire "what set it off?" If a person contracts a disease, we are likely to ask "how did it happen?" On a much loftier plane, when we reflect about the universe, there is the inevitable question "what, or rather Who, started it all?" In principle, these varied queries have at least one attribute in common: they are attempts, whether earnest or casual, to search out the origin of events in nature. Accordingly, they involve not only scientific, but philosophical and even re1igious matters of deep concern. It is evident that, in a broad sense, the phenomenon of nucleation is enmeshed in this enticing concept of "the beginning", but we must extract the scientific component of the problem for our present purposes. Nucleation, as in the case of phase transformations, is best regarded from the standpoint of kinetics. There are then two main steps, which may come in either order: (a) Experimentally, one attempts to measure the frequency with which transformation centers spring into existence; and (b) theoretically, one seeks a model that will account for this observed birth-rate. Temperature, composition, strain, and prior history are some of the important variables that must be considered both experimentally and theoretically when dealing with nucleation in the solid state. Such interaction of theory and observation is an integral part of science in general, but it is particularly significant in the nucleation problem because the very beginning of a phenomenon invariably occurs on too localized a scale in both space and time to be detected with available techniques. Thus, there is little hope of making direct measurements on the nucleus during its birth or to ascertain the exact nature of the process; one can only infer the details of nucleation from the model whose predicted behavior seems to harmonize best with the measured rate of nucleation and its dependence on known parameters. In the field of solid-state nucleation, both theory and experiment call for much ingenuity, but somehow the conceptual schemes have spawned faster than they can be tested by observation. This is not to say that there are many basically new ideas in modern nucleation theory; rather, as we shall see, it is because the required fine-scale measurements are of immense technical difficulty. Quite likely, some of the nucleation models existent today have survived only because of the latitude permitted by meager data. There is great need to bring theory and experiment into better balance in this important area of physical metallurgy. Although one can

Jan 1, 1959

By J. C. Holm

ALTHOUGH the main constituents of Portland cement are the oxides of calcium, silicon, aluminum, and iron, characteristics of the cement are seriously affected by such contaminants in the raw materials as magnesium, phosphorus, sodium, potassium, sulfur, and others of lesser importance. Sources of cement raw materials comprise a long list of minerals occurring in nature in various degrees of purity. The calcareous raw materials are generally limestone of purity varying from calcite to cement rock (a low-grade limestone of natural, almost correct chemical composition), chalk, marl, seashells, coral, and coral sand. The argillaceous raw materials supplying silicon, aluminum, and iron are mainly various forms of clay and shale, to which may be added silicious sand, iron ore, bauxite, or kaolin for minor adjustment of the chemical composition. The quality of Portland cement in this country, as in most parts of the world, is controlled by rigid specifications limiting both its chemical and physical characteristics, and cement manufacturers must comply with these specifications to market their products. Brandon Raw Materials: An unusual deposit of marl, limestone, and clay occurs 12 miles east of Jackson, Miss., near the village of Brandon. The deposit is of sedimentary origin and of relatively young geological age. Layers of marl vary from putty-like consistency to such hardness that it can be cut with a knife. Interspersed between the layers of marl are bands of limestone varying from very soft to hard. the compressive strength of the hardest layers exceeding 15,000 lb per sq in. The layers of marl range in thickness from a few inches to about 25 ft. The limestone bands seldom exceed 2 to 3 ft but often occur in thinner veins in the quarry face. Above the top layer of the deposit, which may be marl or limestone, a layer of clay ranges in thickness from a few inches to more than 20 ft. Part of this clay is harvested with the raw material to supply part of the argillaceous components, but most of it is stripped as overburden and wasted. A highly silicious clay of extreme fineness, harvested from the bottom of the quarry below the marl and limestone bands, is to correct the silica content. Fig. 1 shows typical examples of the interrelation of the various materials, based on drill logs obtained during exploration of the deposit. The marls vary in moisture content in the bank from 15 to 30 pct and contain up to 70 pct -200 mesh particles and up to 40 pct —10 p particles. A large percentage of the fine fraction is within the colloidal range, making the marl extremely sticky. The limestone beds range in hardness from that of the hardest marl to a medium hard limestone and in moisture content from 2 pct to approximately 14 pct. The line of demarcation is often difficult to draw and the moisture content is possibly the best means of classification. The ratio of soft to hard material is not constant throughout the deposit, but the average is approximately 70 pct soft to 30 pct hard material. Through the years this deposit had been repeatedly explored by cement companies and rejected as unsuitable for cement manufacture, mainly because of physical characteristics. In 1950, after careful exploration of the deposit and comprehensive laboratory and pilot plant tests of the raw materials, officials of Marquette Cement Mfg. Co. of Chicago were convinced that a practical and economical method of processing the raw materials had been devised and authorized construction of a new plant that began production in December 1951. Marl and limestone, common raw materials for Portland cement, usually occur in such a manner that they can be worked separately. Their harvesting and processing normally have presented no difficult problems, as standard equipment and methods are available for handling either sticky or hard materials. No other cement plant utilizes a deposit of the nature of that at Brandon, however, and for this reason no prior art was available for design. When properly blended, the raw materials produced an excellent cement without additives. Basic problems to be solved in designing the cement plant were:

Jan 1, 1957

By C. E. MACQUICC

WITHIN a period considerably less than two decades, the engineering view of alloy steels has greatly changed-both as to their composition, and applications. Inasmuch as the elements used in manufacturing alloy steels are substantially the same as those which have been used for the past two or three generations, a statement like the foregoing may reasonably call for some explanation. The first commercial use of alloy steels in this country dates back to the sixties of the last century, when one of the earliest alloy steel patents, covering the use of chromium, was taken out by Bauer. About ten years later, German and French toolmakers began to introduce tungsten into tool steels. Developments along this line were more or less static for 25 years or more, the tool steel, compositions progressing along lines worked out by Mushet and one or two others in Europe. The next step in advance, made by Taylor and White inn the late nineties, consisted of heat-treating the alloy steels to enable much higher cutting speeds, thus introducing what soon became known as "rapid" or "high-speed" steels. All these developments being aimed toward the improvement of cutting tools, the compositions made were essentially of a hard, brittle nature. Following a different line of development started in the seventies, naval ordnance material began to embrace the nickel steels. These were rapidly popularized, became, and still are, with the addition of one or more elements, as chromium, molybdenum, vanadium, standard for heat-treated armor plate. During that period, however, no notable uses were made of alloy steels for engine parts or other high-stress parts where they are now considered indispensable; moreover, the present-day use of metals in the chemical industries was probably not even imagined. After the turn of the century, the necessity for making heavy-duty. machine parts, and especially the develop¬ment of the automobile, caused alloy steels to rapidly supplant plain carbon steels for engineering purposes.

Jan 1, 1930

George B. CoRless, Chairman. Superintendent, Gulf Coast Division, Humble Oil & Refining Co., Houston, Texas. W. H. Geis, Associate Chairman. Geologist, Los Angeles, California. Benjamin C. Craft, Secretary-Treasurer. Associate Professor, Petroleum Enginecring, Louisiana State University, Baton Rouge, La. Executire Committee George B. Corless, Chairman. M. Albertson, Production Engineer, Shell Petroleum Corporation, Houston, Texas. D. R. Knowlton, General Production Superintendent, Phillips Petroleum Co., Bartlesville, Oklahoma. R. P. McLaughlin, General Manager, Dominguez Oil Fields Co., Los Angeles, California. Hallan N. Marsh, Production Engineer, General Petroleum Corporation of California, Los Angeles, California. Theron Wasson, Chief Geologist, The Pure Oil Co., Chicago, Illinois. Production Engineering M. L. Haider, Vice-chairman. Petroleum Engineer, Carter Oil Co., Tulsa, Oklahoma. Joseph Chalmers, DeBataafsche Pet. Maatschappij, The Hague, Netherlands. Emile HugUenin, Deputy State Oil and Gas Supervisor, Los Angeles, California. Carl E. Reistle, Jr., Petroleum Engineering Department, Humble Oil & Refining Co., Houston, Texas. Production J. TERry Duce, Vice-chairman. Geologist, The Texas Company, New York, N. Y. Basil B. Zavoico, Associate Vice-chairman. Geologist, The Chase National Bank, New York, N. Y. Engineering Research R. L. Huntington, Vice-chairman. Associate Professor, Petroleum Engineering, University of Oklahoma, Norman, Oklahoma. Economics Sidney A. SwensrUd, Vice-chairman. Assistant to the President, Standard Oil Co. (Ohio), Cleveland, Ohio. Refinery Engineering Walter Miller, Vice-chairman. Vice-president, Continental Oil Co., Ponca City, Oklahoma. 10

Jan 1, 1938

By Frederick Laist

IN the course of the past 75 years the treatment of copper ores has undergone the most profound changes. To a lesser degree, this is true of all the nonferrous metals, but the rapid increase in the demand for copper due to the phenomenal growth of the electrical industry, and the discovery of vast new ore deposits in Michigan, Montana and Arizona, provided an exceptional incentive for improvements in smelting practice and for large-scale operations. Because these must perforce be carried on in regions where labor was scarce and wages high, the need for mechanization and larger smelting units soon became apparent. At a later date the porphyry coppers were discovered, with ores so low in grade that enormous tonnages had to be treated daily if they were to be made to pay at all. In some instances these ores were associated with, or overlain by, oxidized ores, which could not be concentrated mechanically and, of course, could not be smelted directly. This led to the development of the copper-leaching process. While the principles of the various smelting and leaching processes are for the most part of European origin, and have long been known, modern practice is essentially American and was evolved on this side of the Atlantic. The ores of copper may be divided into three general classes; viz, native copper, sulphide and oxidized ores. By far the greater number of commercially important ore deposits come under the classification of sulphides. Commercial deposits of native copper are limited to the Lake Superior

Jan 1, 1947

By George M. Fowler

MINING geology is a progressive study, so we must look to the future for the solution of many of its most significant problems. These problems, world-wide in scope, offer ample opportunity for the exercise of the utmost skill and intelligence by all that attempt to solve theta, as it is generally recognized that many ore deposits of the future will he found only by months or years of combined intelligent effort by the several engineering groups. Renewed appraisals are continually being made to better understand the relationship of physical-chemical processes to ore deposition and other mineralization and to interpret the findings of the geophysicists and others in terms of economic results. A study of current geologic activi¬ties clearly reflects the growing tendency for cooperation between the different branches of geology in order to appraise their united efforts. In line with these activities arrangements have been made to transfer the geophysical section of the U. S. Bureau of Mines to the Geological Survey.

Jan 1, 1936

By Edwin Ludlow

For many years, coal has been known to exist in the valley of the Sabinas river, in the State of Coahuila, and for about 15 years it has been worked by the Mexican International Railway Co., which opened mines for its own fuel-supply when the railway was built, and has been mining continuously ever since. The coal-basin worked by this company lies along the Sabinas river, principally on the SW. side. It covers a wide area and has been carefully prospected, but only in a few parts have the beds been found sufficiently thick and regular for economical operation. This Sabinas basin was considered the only one in this field, until, in the Spring of 1899, the Las Esperanzas basin was found by Messrs. J. L. Elliot and E. D. Peters, who were in Mexico looking after some copper-properties. After a further examination by Mr. James T. Gardiner, of New York, the Mexican Coal & Coke Co. was organized in June, and active work was begun on Nov. 5, 1899. The coal-field of Las Esperanzas, situated in the State of Coahuila, about 85 miles SW. of Eagle Pass, Texas, adjoins and runs parallel with the Sabinas basin—an anticlinal separating the two outcrops by about 2 miles. Fig. 1 is a sketch-map of a part of the basin. The coal-formation is in the Upper Cretaceous, and corresponds with the Laramie measures of the United States. The following geological section, taken in Nogales canon, shows the measures between the massive limestones forming the Sierra de la Santa Rosa and the outcrop of the coal: Section. Feet. Limestone,...Unknown. Blue shale,.........110 Shale and sandstone,.. 60 Bed of fossiliferous shale,. 60

Jan 1, 1902