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By Noel Jarrett, Allen S. Russell, Bernard M. Starner, Stanley C. Jacobs

A process has been developed to refine high-grade commercial aluminum to 99.99 pct purity. This enzploys precipitating titanium, vanadium, and zirconiu~ as borides. The upgraded liquid is partially crystallized under conditions that prevent massive freezing. The resulting crystals are compacted and washed free of adhernig impure liquid aluminum by melting the top crystals while draining off the liquid. Finally, the bottorn portion of the crystal bed is melted and removed as the pure product. Leakage from the crystallizat~on vessel is prevented by a layer of alumina granules that are not wetted by the aluminum. ALUMINUM of 99.99 pct purity is desired in a variety of applications. These include electrolytic capacitors, catalyst carriers, decorative trim for automobiles, aluminum powder, and high-strength alloys. This market was for many years filled by refining commercial-purity aluminum in a three-liquid-layer electrolytic cell of the type originally proposed by Hoopes. To meet the expanding need for lower-cost high-purity aluminum, a refining process based on chemical precipitation and fractional crystallization was developed. The availability of this super-purity metal was announced in November 1961, and three patents1-3 relating to the process were issued in 1965. An alternate process, comprising continuous fractional crystallization of a portion of a liquid-aluminum feed stream under conditions of strong agitation at the surface of the growing crystals, was published by Dewey4 in 1965. Earlier proposals by Larsen 5 and by Regner6 also emphasized the advantage of rapid agitation of the melt in the region of the crystallization zone. johnson 7 more recently proposed extracting purified aluminum from an alloy by mixing crystals of pure aluminum into the molten alloy, allowing them to grow, and removing the pure aluminum as by casting. Aamot's 8 recent patent describes a freeze refining process that involves controlled partial freezing against cooled moving retort walls. The Alcoa process to produce high-purity aluminum is schematically described in Fig. 1. Relatively pure aluminum is treated with boron in a furnace (a) to precipitate high melting point impurities, the supernatant liquid is transferred to a crystallization vessel (b), the liquid is partially crystallized with mechanized "tamping" (c), the remaining impure liquid is tapped out and the crystal bed partially and directionally re-melted to wash the underlying crystals (d), and the balance of the crystals is melted and withdrawn as high-purity aluminum (e). PRINCIPLES OF FRACTIONAL CRYSTALLIZATION Commonly encountered impurity elements form two types of systems with aluminum. Titanium, vanadium, and some other transition elements in periodic groups IV, V, and VI are the high melting point impurities. Initial solidification of aluminum containing small percentages of these elements will produce solid markedly enriched in them at temperatures slightly above the freezing point of high-purity aluminum. Most other elements, such as silicon and iron, produce eutectic type reactions with aluminum. In this case the first solid formed on initial solidification at temperatures slightly below the freezing point for high-purity aluminum is markedly depleted while the remaining liquid is enriched in these elements. The equilibrium change in composition during solidification of aluminum contaminated with silicon, iron, or titanium is illustrated in Fig. 2. Here, for clarity, the temperature scale is expanded beyond the

Jan 1, 1968

By W. L. Fink, L. A. Willey

During the war there was introduced a new higher strength aircraft alloy designated 75S.1,2,3 The properties of this alloy assure extensive applications in both military and commercial aircraft. It is therefore important to understand its limitations as well as advantages. The properties of 75.5 alloy in the heat-treated tempers, like those of many other aluminum alloys, are affected by the rate of quenching. In general, low quenching rates tend to cause low strengths and to adversely affect the resistance to corrosion. Commercial quenching procedures are usually sufficiently rapid to permit the development of maximum properties. However, in the center of heavy sections, such as large rolled and extruded shapes, the quenching rates may not be rapid enough to develop maximum strength or resistance to corrosion. The investigations of 75s alloy described herein reveal the most critical range of temperature and the effects of quenching sheet and extrusions at different rates through that temperature range, on the tensile properties and resistance to corrosion. Procedure Preparation of Specimens Sheet specimens (3 in. by 9 in.) were prepared from a commercial lot of 75s "as rolled" sheet (0.064 in. thick). The composition4 was as follows: Weight Percentage Cu Mn Mg Zn Cr A1 with Normal Impurities 1.64 0.16 2.58 5.66 0.27 Remainder The specimens employed for the determination of the time-temperature relations during quenching of sheet were prepared by the following procedure: the hot junction of a 28-ga. iron-constantan thermoelement (asbestos insulated) was brazed to a thin strip of aluminum which was in turn brazed into the end of a 3/16-in. id by %-in. od by 30 in. long aluminum protection tube. Before brazing, the tube was flattened to 0.064-in. thickness over the junction and adjacent lead wires for a distance of I 1/2 in. The flattened end of the tube was fitted into a slot cut from one edge to the center of the 3-in. by 9-in. by 0.064-in. sheet and brazed into place. The brazed joint was dressed to the thickness of the sheet and the entire specimen buffed to approximately the brightness of "as rolled" material. Because of the brazing operations required, these specimens were prepared using 3S alloy. For the investigation of quenching rates in heavy sections, there were used 75s extrusions which had compositions similar to that of the sheet. The specimens consisted of 14 in. lengths of 3i-in., 2-in., 3-in, and 4-in. diam cylindrical rods and a roughly rectangular extruded section which was approximately 4 in. by 7 1/2 in. Thcrmocouple~ were peened into the bottoms Of .1/8-in. diam wells drilled into one end and parallel to the axis to a depth of

Jan 1, 1949

By L. A. Roe, John Jan

Iodine is a soft, lustrous, grayish-black nonmetallic element with a density of 4.9. It is the least active of the four members of the halogen family. The other members are, in order of increasing activity, bromine, chlorine, and fluorine. Iodine is a solid at ordinary temperatures, while bromine is a liquid and chlorine and fluorine are gases. Iodine melts at 113°C and volatilizes at 184.4°C to a blue-violet gas with an irritating odor. It occurs in nature only as iodates and iodides or other combined forms. It was discovered by Bernard Courtois in France in 1811, who noticed its presence as an unknown substance in crude soda ash obtained from burning seaweed. Gay-Lussac recognized it as a new element and named it iode, from the Greek word "ioeides or iodes" for violet color (MacMillan, 1970). The world production is not known with any great certainty, but it is probably between 25 and 35 million lb per year, of which about 30% is consumed in the United States. Geology and Mineralogy Iodine compounds occur as a minor constituent as a mineral in the Chilean nitrate deposits and in solution in brines and seawater. According to the US Geological Survey, it is the 47th most abundant element in the earth's crust. The minerals lautarite, Ca (I03)3 (calcium iodate), and dietzeite, Cat (103)2 (CrO4), (calcium iodate-chromate) are found in Chilean nitrate deposits which are located in Antofagasta and Tarapaca provinces on the eastern slope of the coast range in a desert area. Various brines contain iodine compounds. Seawater contains about 0.05 ppm of iodine and some seaweeds will extract and accumulate it up to 0.45% on a dry basis. Some coals in West Germany also contain iodine compounds. The known and potential sources of iodine reported in 1968 are given in Table 1. Table 2 lists estimated world iodine reserves. Iodine has been recovered from brines in Java, Indonesia, France, England, and the USSR. Iodine has also been recovered from seaweed in Ireland, Scotland, France, Japan, Norway, and the USSR. The indicated reserves and future resources of iodine are large but have never been adequately measured. Analysis Iodine as the free element can be detected by the characteristic blue color it gives to a starch solution. Quantitatively it is determined as the free element by titration with standard thiosulfate solutions using starch as an indicator. Colorimetric methods are also applicable. Markets and Prices Iodine and its compounds are generally marketed in the form of: iodine, crude; iodine, resublimed; calcium iodates; calcium iodide; potassium iodide, sodium iodide, and numerous organic compounds. Product Specifications Crude iodine, World market: 99-99.5% 12. Crude iodine, US produced, average: 99.8% 12. Crude iodine, USP XVII Specs: not less than 99.8% percent I2. Resublimed iodine is usually 99.9% and ACS specifications call for not over 0.005% total bromine and 0.020% nonvolatile materials (Anon., 1971). Prices, c.i.f. United States, for iodine have been steadily increasing from $1.18 per lb of crude in 1967 to $6.37-7.27 in January 1981 (Anon., 1981). In 1980 the price of iodine increased by 50%.

Jan 1, 1983

By W. H. Emmons

INTRODUCTION MINERAL deposits that have formed by the various geologic processes, when exposed to air and water at or near the surface of the earth, break down and form new compounds that are stable under surface conditions. Mechanical disintegration of the ores proceeds along with chemical alteration which generally is attended by oxidation, carbonation and hydration. Essentially all minerals are affected-silicates, carbonates, native metals, sulphides, etc. Where iron sulphides are present, oxidation yields sulphuric acid, and in the presence of oxygen and iron, ferric sulphate, a powerful solvent, is formed. Above the water level, in the vadose or shallow zone, both air and water are present. Below the water level air is excluded and that which is carried down with water is removed from the solution by reactions with reducing materials. Above the water level, solution is the pre-dominating process; below the water level, precipitation generally is equally important. In some deposits, particularly above the hater level, valueless materials are removed from the ore, leaving certain metals in a more highly concentrated state. This type of alteration, which has been termed negative enrichment, is common in ores of iron, aluminum, manganese and certain other metals. Some gold deposits, particularly those in which the environment is unfavorable for solution of gold, have been enriched near the surface by removal of material other than gold. Certain metals are readily dissolved in an oxidizing acid environment. These include copper, silver and, under certain conditions, gold. In the presence of iron sulphides, deposits of these metals are likely to be leached above the water level. The metals are carried downward to depths where air is excluded, and where they may be redeposited, generally below the water level. Such enrichment by addition of metals has been termed positive enrichment.

Jan 1, 1933

By Henry M. Howe

This paper is a discussion of the extremely valuable one of Mathewson and Phillips, The Recrystallization of Cold-Worked Alpha Brass on Annealing,1 which not only gives us a wealth of important data reached with great intelligence, but also shows both uncommon powers of imagination and a perfectly fair spirit. Let me try to analyze some of their results, and to enunciate some of the laws to which these results point. For brevity I refer to them as "The Authors." The page numbers in parentheses refer to their paper. 1. The Visible Aspects of Recrystallization.—Plastic deformation in a single direction, as in cold-rolling, draws the grains out in that direction, that is, inequiaxes them, without destroying their apparent individuality. Each grain seems to endure the drawing out without changing either its volume or its orientation materially, for the etching tint of each grain seems to be as uniform after as before the drawing out, save for the "etch bands,"2 shown in Figs. A to D of the Authors' Plate I. As the drawn-out metal is heated progressively, on reaching a certain "disintegration temperature" these old grains seem to break up, probably into submicroscopic fragments, and this apparent disintegration is followed by a coalescence of these fragments, so that their number decreases and their size increases, till they may become very much coarser than before the drawing out. Ruder3 coarsened the grains of silicon steel in this way till single grains reached an area of 50 cm. (7.75 sq. in.). The deformation itself probably breaks each grain up into many very small fragments, but the fact that each grain continues to have a uniform etching tint different from that of its neighbors indicates that these fragments retain the initial common orientation of the grain. The apparent disintegration which we observe, then, is rather an abandonment of community of orientation for individuality of orientation, by the fragments formed earlier during the deformation. Hence we

Jan 1, 1917

By J. R. Campbell

In order to discuss the subject intelligently, it will be necessary to touch briefly on the forms in which sulphur is supposed to exist in coking coal to be carbonized in beehive or byproduct ovens. Sulphur is known to exist in coal as sulphides and sulphates, as can be determined experimentally. Then there is the so-called organic sulphur, i.e., sulphur in combination with the carbon, 'hydrogen, and oxygen of the coal, about which much has been written, but nothing definitely proven in an experimental way. In fact, so far. as we know, there never has been developed a satisfactory and conclusive method in the laboratory for the direct determination of organic sulphur. For most coking coals, it can be safely assumed that the preponderance of sulphur is in the form of pyrite (FeSz). When exposed to comparatively low temperatures during the coking process, it loses its sulphur according to the following chemical reaction: 7FeS2 = Fe7Ss + 6S. It will be seen, therefore, that six out of the 14 atoms of sulphur (or 42.8 per cent.) are expelled, or volatilized. FelSa remains in the coke as pyrrhotite, or magnetic sulphide of iron; this accounts for the highly magnetic properties of the powdered coke. A more commonly accepted reaction is FeS2 = FeS f S, in which the straight sulphide of iron is produced with 50 per cent. volatilization of sulphur. In the beehive methods of coke making, air is introduced in sufficient amounts to carry on the distilling and the coking processes, and the sulphur is oxidized along with the other volatile products: First, into sulphur dioxide (SO2), known by the pungent andsuffocating odoremitted from the trunnel head; second, into sulphuric anhydride (SOa); and, finally, into sulphuric acid, as it comes into contact with the air and moisture. In a properly regulated draft on a beehive oven, there is never complete combustion of the gases. In other words, the coking process should be carried on in a reducing atmosphere, and a low-grade producer gas kept issuing from the trunnel head. For coals of about 30 per cent. volatile matter, the ratio of air to gas is 3½ to 1. In complete combustion, the ratio is 6 to 1, producing an extremely high temperature

Jan 1, 1916

By Robert H. Richards

Very little has been published recently on this subject in the mining journals or proceedings of societies. The attention of experts has been diverted perhaps by the demands for pan amalgamation of refractory ores. Yet free milling ores occur in many localities, and it may be interesting to have on record some data as to details of running a small test-mill, especially as details of results do not seem to be accessible to stndents and investigators. Küstel, in 1863, under battery amalgamation, dismisses the subject by stating that "amalgamation on copper-plated platforms, troughs, and other copper fixings" is " very imperfect, and mostly abandoned." J. Arthur Phillips says, in 1867, under placer mining : " A well-amalgamated copper plate is considered as effective for

Jan 1, 1880

By JOHN R. SUMAN

I WOULD like to spend a few minutes describing to you the present condition which exists in the oil industry and then point out some aspects of this deplorable situation in which I think petroleum engineers can be helpful. As you know, the oil business at this time is in a very critical condition, .due to the tremendous potential production in excess of current demand. This is a world-wide condition as well as a national problem, as it is estimated that the surplus production available for the market in foreign countries is of about the same proportion as that existing in the United States. Due to the inability within the United States to hold production within the bounds of demand prices have been slumping for the last four years and at this time have reached the point where the sales value of the average barrel of crude oil in the United States, is far below the cost, of production. In addition to the large amount of potential production available for the market in excess of demand we have in storage in the United States about six hundred fifty millions of barrels 'of oil. Unless something can be done to limit the amount of oil coming onto the market to a point well below the demand, which point will permit the reduction of stocks, it looks as though the 'oil business is facing demoralization.

Jan 1, 1931

By Richard W. Lodge

Several methods, both wet and dry, for the assay of zinc-box residues from the cyanide process, have been described in recent years, and each of them has been claimed to be superior to all others. In the year 1901, a paper, entitled "Assay of Zincy Precipitates," was published ill the School of Mines Quarterly to the purport that the scorification method for the assay of zinc-box residues was absolutely unreliable. In order to shed light on this matter, the following experiments were undertaken by Messrs. C.B. Hollis and F. D. Kehew, undergraduate students at the Massachusetts Institute of Technology. The zine-box residues used were obtained through the courtesy of Mr. H. R. Batcheller. The samples were very rich and varied greatly in the fineness of their condition. SCORIFICATION-ASSAYS. In the preliminary tests, the charge, which was weighed on a chemical balance, consisted of 0.1 Assay Ton of residues mixed with from 30 to 35 grammes of test-lead and placed in a 3-in. scorifier, over this an additional quantity of test-lead (from 30 to. 35 grammes) was placed for a cover, and borax-glass, varying in quantity from 3 to 15 grammes, was sprinkled over the top of each charge of the various assays for a cover. The charges were scarified in a muffle-furnace heated to the ordinary temperature which is used in scorification; in some cases the door of the muffle was left open, while in others it remained closed. Generally, the charges spit badly, especially in the assays that were made with door of the muffle left open, or in those in which the door was opened too quickly. The results of the preliminary assays showed: 1. That in order to obtain approxi-

Jan 1, 1904

By L. C. Chang, T. A. Read

Diffusionless transformation in Au-Cd single crystals containing about 50 atomic pet Cd was investigated by means of X-ray analysis of the orientation relationships, electrical resistivity measurements, and motion picture studies of the movement of boundaries between the new and old phases during transformation. The nucleation of diffusionless transformation by imperfections and the generation of imperfections by diffusionless transformation were discussed. THAT connections exist between plastic deformation and diffusionless phase changes has long been recognized. Thus it is often possible to produce a diffusionless phase change in a temperature range, above that in which the change occurs spontaneously, by cold-working the initial phase. Certain aspects of the dislocation theory of the plastic deformation of crystalline solids also provide for a rather direct connection between the processes involved in plastic deformation and in diffusionless phase changes. Heidenreich and Shockleyl have pointed out that simple edge dislocations in f.c.c. metals are probably unstable, and that the more probable lattice imperfections, called extended edge dislocations, consist of two half dislocations separated by a distance of the order of magnitude of 100A. The region about two atomic planes thick between the half dislocations because of this stacking fault may be described as having the hexagonal close-packed structure. Presumably the stacking faults observed by Barrett" fter cold-working f.c.c. Cu-Si alloys resulted from the passage of such half dislocations through the lattice of the initial phase. It is now becoming clear that the development of a detailed theory of the atomic movements involved in diffusionless phase changes will require a consideration of the role played by lattice imperfections, just as such considerations are necessary to the understanding of plastic deformation mechanisms. This point of view has been recently set forth, for example, by Cohen, Machlin, and Paranjpe3 who pointed out the role which might be played by screw dislocations in nucleating diffusionless phase changes. The present paper reports on some aspects of the diffusionless phase change in single crystals of the beta phase alloy Au-Cd which serve to emphasize further the importance of lattice imperfections in diffusionless phase changes. The diffusionless phase change of Au-Cd possesses several remarkable features. One of these is that the interface between the high-temperature beta phase and the low-temperature orthorhombic phase typically moves with a low velocity, in contrast to the behavior observed in the transformation of austenite to martensite. Motion pictures of this slow interface motion have been prepared in the course of the work reported here. Another important feature of the Au-Cd transformation is the small amount of undercooling observed. The reverse transformation occurs on reheating to a temperature only 20" higher than the transformation temperature observed on cooling, and under some circumstances the hysteresis observed is substantially less than this. This narrow temperature range between transformation on heating and cooling is presumably in part a consequence of the fact that the transformation requires a lattice shear of only about 3". Finally, the orthorhombic product phase possesses unusual mechanical properties, as was first pointed out by olander' and Benedicks." After completion of the transformation on cooling the specimen can be severely deformed, yet on the release of load it springs back to its original shape in a rubber-like manner. Explanation of this phenomenon will require an understanding of the lattice imperfections in the orthorhombic structure and, correspondingly, of those in the initial body-centered cubic structure. Single crystals of Au-Cd alloy containing 47.5 and 49.0 atomic pct Cd were prepared from fine gold (99.95 pct purity) and chemically pure cadmium (99.99 pct purity) by melting the alloy in an evacuated and sealed fused quartz tubing and growing into single-crystal form by the Bridgman method. The Au-Cd alloy containing 47.5 atomic pct Cd undergoes a diffusionless transformation from an ordered body-centered cubic structure to an orthorhombic structure when it is cooled to about 60°C, while the reverse transformation takes place when the alloy is heated to about 80°C, according to electrical resistivity studies. The structures of these two phases have been studied by Blander,4 reinvestigated by Bystrom and Almin.e he lines of Debye photo-gram of powdered samples of Au-Cd alloy containing 47.5 atomic pct Cd prepared in this laboratory were identified and agreed fairly well with those of

Jan 1, 1952

By David J. Mack

The structures and properties of the copper-aluminum alloys have been the subject of much study since the classic investigation of Carpenter and Edwards1 focused attention on. the engineering utility of these alloys. It was recognized at an early date that the metallographic structures developed in the aluminum bronzes were similar to those developed in steels, both in the annealed and the rapidly cooled state. Most investigators have been concerned with the acicular, martensitic-like structure formed from the 0 solid solution upon rapid quenching; the transformation of the ß under equilibrium cooling to a lamellar eutectoid having been relatively neglected. With the introduction in 1930 by Davenport and Bain2 of the isothermal transformation technique for studying eutectoidal decompositions, a new field was opened. Although an enormous amount of work has since been done on the isothermal transformation of steel, study of structurally analogous systems has been almost totally overlooked. The outstanding exception was the prize-winning paper† of Smith and Lind1ief³ ho investigated the decomposition of the 0 phase in copper-aluminum alloys by isothermal methods. This was followed in 1934 by Wasserman's review' of available information on analogous transformations in eutectoid alloys. Since that time no comprehensive study of isothermally transformed eutectoids analogous to steel has appeared, although many valuable contributions have been made to an understanding of the structures developed in such systems. Important papers have been published by Kurdjumow, Gridnew and co-workers, Obinata,18.'9 Greninger,20.21 and Others. The work to be described in this paper was an outgrowth of preliminary studies on the isothermal transformation of a entectoid aluminum bronze, after it became apparent that the alloy under study was reacting somewhat differently than the similar alloy used by Smith and Lindlief. Preliminary Experiments The material used in this study was a high purity aluminum bronze especially prepared by Ampco Metal, Inc. It analyzed: Copper—88.07 pet, Aluminum—11.89 pct, Iron-—0.02 pet, Manganese—-.OI pct, Others—Balance. Although some disagreement exists on the exact composition of the eutectoid, this alloy was believed to be of essentially eutectoid composition even though some pro-eutectoid* delta particles existed in the microstructure of furnace cooled specimens. Specimens transformed isothermally at temperatures slightly below the eutectoid showed relatively large amounts of pre-eutectoid delta, but as will be shown later, this results

Jan 1, 1949

In 1820, the Board of Public Works was considering some improvements to the canal, in order to reduce the cost of transportation, and in its annual report for that year gives a description of the method of loading the coal from the pit to the boat, and also from the boat to the dealer's yard, which is illuminating in showing how coal of this type should not be handled. It follows:- "It will be seen by the estimates, that the improving the present canal, forming a canal of large dimensions, from the head of the present lower canal to Sabbot Island; erecting locks of large capacity, and making a communication with the river, so as to completely accommodate the coal trade, (except it should hereafter be found necessary to make another communication with the river,) will not cost more than 126,000 dollars. But as there is some doubt whether the streams that may be received into the canal between Sabbot Island and the upper arch, will at all times be competent to supply the locks on that portion, we will extend our calculation to a point nearly half a mile above Pleasants' Island; where, by erecting a dam, any desired quantity may be thrown into the canal. This extension of the canal with one lock, and the dam across the river, is estimated at 34,000 dollars, making in the whole a little over 160,000 dollars. There will then remain a surplus of 40,000 dollars after completing the works to the point last mentioned. "In order to discover what effect the improvement of this first section will have on the tolls, it will be necessary to take a view of the present state of the coal trade, and endeavor to ascertain what change will result from the increased facility of transportation. "That part of the business which is carried on by water, is conducted nearly in this way. When the coal is drawn out of the mines, it is thrown in a heap near the mouth of the mine, or shaft; it is then loaded into carts, and carried to the river bank, where, in some instances, it is discharged from the cart at the brow of the bank, and runs down to the beach near the water's edge; then shovelled into wheel-barrows, and wheeled aboard of the boat, and discharged from the barrows by upsetting. In other instances, the carts are driven on to a kind of scaffold, furnished with a wide spout or director at the edge; by which the coal is conveyed immediately into the boats. These boats are the common James river poplar batteaux, and require three men to each. The up-stream navigation being laborious, the boats are built of light materials, and continue fit for service but a short time, (say) from two to three years; their cost, when new, from fifty to one hundred dollars. "When the river is tolerably flush of water, one of these boats will carry about two hundred bushels; but in low water their load is sometimes diminished to one hundred, and even as low as eighty bushels. They pay for passing the canals and locks to the Basin, one dollar per load; so that when full loads are taken, it will amount to half a

Jan 1, 1942

By E. A. Elevatorski

Wollastonite, named after William H. Wollaston, an English chemist, is a calcium metasilicate, CaSiO3. It has a short history as an industrial mineral. The earliest production of wollastonite is reported to be from a deposit near Code Siding, located north of Randsburg, Calif. At this locality small tonnages of wollastonite were quarried during 1933-34 and 1938-41, and processed into mineral wool. This operation was largely experimental and virtually no United States production was again reported until the 1950s when a large deposit near Willsboro, N.Y., was developed by the Cabot Corp. A processing plant was placed on-stream in 1953, with nearly continuous production to date, and it is currently operated by Interpace Corp. Since 1958, wollastonite deposits in the Little and Big Maria Mountains of Riverside County, and in the Panamint Range of Inyo County, both in California, have operated intermittently for production of both ornamental and commercial wollastonite. During 1973, the United States was the major producing country, furnishing about 75% of the world's output. Recent production also has come from Finland, Mexico, and Kenya. Small amounts have been shipped intermittently from India, USSR, New Zealand, Republic of the Sudan, Republic of South Africa, and South-West Africa. The principal use of wollastonite is in the manufacture of ceramics, especially wall and floor tiles. Other uses are for paints, fillers, adhesives, reinforcing agents, plastics, fluxes, and glazes. Mineralogy Pure wollastonite, CaSiO3, has the composi¬tion of 48.3 % CaO and 51.7 % SiO,. However, it is seldom found in the pure state due to the ease with which it takes into solution the metasilicates of manganese, magnesium, iron, and strontium. Predominantly, wollastonite occurs as a contact metamorphic deposit forming between limestones and igneous rocks. Commonly associated minerals are garnet, diopside, epidote, calcite, and quartz. It has a specific gravity of 2.8 to 3.0, and hardness of 4.5 to 5 on Mobs' scale. When pure, it has a brilliant white color, but with impurities it may be grayish or brownish. Luster is vitreous to pearly. Melting point of wollastonite is about 1540° C. Wollastonite occurs in coarse-bladed masses, rarely showing good crystal form. It is usually acicular or fibrous, even in the smallest of particles. The most unique property of crushed and ground wollastonite is its cleavage. Fragments of crushed wollastonite tend to be needle-shaped, imparting a high strength, and this property is the basis for many of its uses. The fiber lengths are commonly in the ratio of 7 or 8 to 1, length to diameter. Some crystals of wollastonite fluoresce under short-wave or longwave ultraviolet light, or both; colors ranging from yellow-orange to pink-orange. Specimens may also show phosphorescence. The brightness of wollastonite is a property of considerable importance to the paint industry. Material, 99% pure, with a size of -325 mesh, has a General Electric reflectance rating of 92 to 96%. Chemically, wollastonite is inert and this property makes it useful as a filler and reinforcing agent. There are two polymorphs of calcium silicates: wollastonite, a low temperature form, and pseudowollastonite, a high temperature form. Inversion of wollastonite to pseudowollastonite occurs at about 1120° C, resulting in an increase in the coefficient of expansion and a color change. Pure white wollastonite, on inversion, may change to a cream tint, or various shades of red or brown. The color change is thought to be due to the presence of iron and strontium.

Jan 1, 1975

By Robert Mehl

PART I. ORIENTATION RELATIONSHIPS IN OXIDE LAYERS Oriented overgrowths and intergrowths among both metallic and nonmetallic substances have been recognized and studied for well over a century. The work of Widmanstätten in 1808 on the geometrical struc-ture in meteorites, a structure known by his name, demonstrated that oriented intergrowths can occur in purely metallic systems. This fact led to much of the early microscopic study of alloys, contributing greatly to the advance of physical metallurgy. The problem has been attacked again in recent years in a comprehensive fashion, with the object of dis-covering what atomic movements may occur during phase changes in alloy systems. Much of this work has appeared in the A.I.M.E. TRANS-ACTIONS in a series of papers published by Mehl and coworkers beginning in 19311. Although many aspects of this general problem remain unsolved, it may be said that the orientation of a new phase forming by precipitation from solid solution or by transformation invariably bears, a unique relationship to the orientation of the phase from which it formed, and that similarity in atomic patterns on atomic planes in the two phases play an important part in determining the orientation relationship. Analogous orientation relationships exist in oriented intergrowths in nonmetallic systems-mineral or inorganic. In 1827 Haidinger2 dis-covered natural intergrowths of hematite and magnetite, and demon-strated that the rough form of the magnetite octahedrons was delineated by small crystals of hematite, of which the basal (00.1) planes lay parallel to the octahedral cleavage planes of the magnetite. The description of this orientation relationship was later completed by von Rath3, who showed that the edge (00-1):(10-1) in hematite lies normal to the [111]

Jan 1, 1937

By William E. Newman

The smelting of galena in the ore hearth has been practiced in many countries for several hundred years with varying success. In the United States, the water-jacketed American hearths and the Jumbb hearths have found some favor in the Missouri lead belt, where large quantities of non-argentiferous galena concentrates are produced. In form and method of operation the ore hearth has changed but little since its earliest conception. A detailed description of the furnace is lot needed here; it has been fully described in most works on the metallurgy of lead and in many technical papers. Since its field is restricted to non-argentiferous galena, containing over 68 per cent. of lead, its use is limited to a few districts; and, on account of certain disadvantages attending its operation, modern sintering and blast-furnace practice has nearly driven it out of the Missouri field. It is not generally known that the cost of producing pig lead is smaller by the hearth method than by sintering and blast-furnace smelting. Yet it is doubtful if any metallurgist knowing this to be true would recommend an American hearth installation—by reason of the disadvantages which will be briefly enumerated. The furnace has been limited to a length of from 4 to 5 ft., requiring for its operation two men working an 8-hr. shift as a maximum. The product per man is small; the work is hot and laborious; and the difficulty of completely removing the dust and fume has made it a notorious source of lead poisoning, Although suitable for operations on a small scale a large number of hearths would be required for a plant smelting 10,000 tons of 68 to 70 per cent. concentrates per month; and the number of semi-skilled laborers would be six times the number of hearths—a condition which is prohibitive. On account of the high percentage of dust and fume produced, a large flue and bag-house installation is required and, in the past, the handling and re-treatment of this dust and fume has -been a serious problem.

Jan 1, 1916

By James E. Howard

At the request of the Council of the Institute, I have the honor to submit the following remarks upon the Program of Tests under which the current work of the Watertown Arsenal Testing Laboratory is carried on, which comprises, among other items, the tests of steel ingot metal and derivative shapes. The intended scope of the tests may be illustrated by extracts from the descriptive part of the program as submitted by the Laboratory under date of April 17,1907, and subsequently approved by the Chief of Ordnance, U. S. A. Under Item 1, Ingot Metal—Open hearth, acid and basic; Bessemer, acid and basic; crucible; fluid compressed and uncompreesed—descriptive remarks were made as follon-s: "A thorough, fundamental inquiry into the physical properties of steel necessarily begins with the ingot metal. Investigations, having for their object the improvement of steels, should also begin with the ingot. A knowledge of the ingot structure is essential for judging of the subsequent behavior or appearance of the metal. Under ordinary conditions, so little information is obtained from the ingot in individual cases that practically none of importance is acquired. These remarks have particular reference to the state of physical and structural

Jan 1, 1909

By Henry S. Washington

During the last twenty years or so the chemical investigation of rocks has made great advances, and it is now generally recognized that a knowledge of the chemical composition is as essential as that of the texture or mineral composition—if not more so—for the proper classification of rocks and study of their origin and relationships. Rock-analyses have vastly increased in number and, what is of greater importance, in quality. New and improved methods permit of greater accuracy than was possible in the early days, and the list of chemical constituents frequently determined has risen from the seven or eight of the greater part of the nineteenth century, to twenty or more. Indeed, rock-analyses with determinations of so many constituents are now commonly made by the chemists of the United States and Australia, while in Germany, Great Britain, France, and Italy the rarer constituents are determined more frequently than formerly. As a consequence of this modern, accurate work, it has been discovered that some elements which were formerly supposed to be rare are of wide-spread occurrence and are often present in considerable amount. The fact is further being developed that the elements tend to show certain relations of occurrence or abundance in connection with each other. This is a fact which is applicable to the rarer elements, and which also finds a broad geological and petrological expression in the recognition of petrographic provinces. We are beginning to obtain some definite, though as yet rudimentary, knowledge of the distribution of the elements among igneous rocks. Some of the results along these lines obtained by study of the vast accumulation of analytical data now available are well known to petrologists, while others do not seem to be so gener-

Jan 1, 1909

By T. C. King

AT the new Graham-Central Mill of Eagle-Picher, near Galena, Ill., material is simultaneously dewatered and introduced into the ball-mill scoop boxes by the use of variable-speed, 24-in. spiral classifiers. This arrangement has proved satisfactory in that the moisture content of the wet feed is reduced, thus allowing maintenance of density within the mills, and a constant feed at any desired rate to the mills is provided. In this mill the primary feed is wet crushed to minus 1/2 in. and preconcentrated by jigs to produce a bulk lead-zinc-iron concentrate and a waste tailing. The jig concentrate is then dewatered by a conventional dewatering classifier and stored in bins ahead of the ball mills. Even though this material is well dewatered, the discharge at the bin bottom is sloppy because of the gradual drainage of the water from the surface of the particles. Conventional belt feeders with vertical cutoff gates are unsatisfactory because of the flushing characteristic of the wet sand.

Jan 9, 1950

Colorado School of Mines Scientific Society held its first meeting on Friday evening, Jan. 14.1916. H. C. Parmalee gave an interesting talk on the Loss of Cyanide by Hydrolysis. F. E. BRIBER, Secretary. The School of Mines Society of the University of Minnesota held a meeting on Thursday evening, Jan. 13, 1916, at which Fred A. Jordan gave a talk on Magnetic Concentration of Iron Ores. Mr. Jordan is at present testing the new magnetic concentrator designed at the. School of Mines Experiment Station. This apparatus, if successful, will open up an enormous tonnage of ore on the Cuyuna and Mesabi ranges. ADOLPH DOVRE, President. At the College of Mines, University of Washington, Seattle, 33 mining men, with experience varying from one to 25 years, have enrolled in the 19th Annual Three Months' Short Session. At the annual smoker tendered the Short Session miners by the student branch of the American Institute of Mining Engineers, Capt. R. H. Stretch of the Alaska Bureau, Seattle Chamber of Commerce, delivered an address on The Mineral Belts of Alaska.

Jan 3, 1916

Bailey, Lewis Newton, Master Engineer, Senior Grade, 4th Regiment, U. S. Engineers, Headquarters Company, died of pneumonia at Camp Merritt, N. J., on April 30, 1918. Baird, Louis, Lieut., Royal Field Artillery, British Army, died on the battlefield in 1915. Ballamy, John H., Capt., 103c1 Engineers, killed in action near Fismes, Aug. 9, 1918. Bowles, Martin F., 2d Lieut., Co. B, 355th Infantry, killed in action, Sept. 3, 1918. Burt, Andrew, died in active service, 1916. Cobeldick, William Morley, Royal Engineers, died from gas poisoning on Oct. 7, 1915. Dougall, Ralph,. 4th University Co., Princess Patricia Regiment, killed in action early in the war. Evans, Alfred Winter, Lieut.-Col., New Zealand Rifle Brigade, D. S. 0., D. C. M., killed in action on Oct. 12, 1917. Gordy, Sheppard B., died in service, Oct. 9, 1918. Gorman, Thomas C., Lieut., Canadian Engineers, killed in France, Mar. 18, 1918. Hague, William, 1st Lieut., Engineer Officers' Reserve Corps, died in active service, Jan. 1, 1918.

Jan 1, 1919