Search Documents

By O. A. Cheadle, F. E. Lane

ThE computer program for arbitrary crystal systems reported by Camp and Clum' has been modified to make it more convenient for hexagonal crystals. The program' uses the Miller indexes (hkl) which can be confusing for hexagonal crystals while the modified program uses the Miller-Bravais indexes with four axes; e.g., the angles between the (110) planes, Fig. 1, are 0 and 90 deg but in the (hkil) system the angles between the (1150) planes are 0 and 60 deg. If a Laue photograph is taken of a crystal oriented with the prismatic planes nearly parallel to the film then the spots on the stereo graphic projection will be from high-index planes. The probable positions of the low-index planes, e.g., (0001) plane, can only be obtained from the intersection of zones and this is not accurate to 1 or 2 deg. The number of planes considered by the program (card 1)' has to be limited to the ones of low index or the program time is excessive but a solution will not be obtained if one of the spots has an index that is not being considered. To overcome this problem the program1 was modified so that if no fit was obtained at *1 deg (card 3) of the tabulated angles then ±2 or ±3 deg was tried. If still no solution was obtained either due to one of the angles not being measured correctly to ±3 deg or because one of the spots was from a high-index plane, then the last spot was discounted and a fit tried for the remaining spots at i1 deg, and so forth. The minimum number of spots that the program will try to fit is five. If the limit on any individual index is 4 (card 1) and (h + k + l + 1) is six then twenty-three planes are considered and there are over 1000 interplanar angles. Many pairs of planes have very similar interplanar angles and with the errors previously mentioned the program will often produce several alternative solutions to a group of spots particularly at ±2 or ±3 deg. However without the program the alternative solutions would probably not have been found. If a large number of spots are used the number of possible fits is reduced. In the example shown in Fig. 2, if only spots which are on the film are used (case 1) the program gives six possible solutions, Table I. However if points 7 and 8 are also used (case 2) the program gives only one fit which also agrees with a standard projection of the crystal. In addition to time-saving the program ensures that a correct solution is obtained since it is unlikely that all the alternatives would have been gound manually; the first would probably be assumed to be the correct solution. The program has been used for zirconium crystals but is equally suitable for other hexagonal materials.

Jan 1, 1969

By H. R. Hendricks

THE ore of the Iron King Mine, being very hard and having a very fine crystalline structure, presents many problems in milling that are not present in ordinary lead-zinc ores. This very fine crystallization causes much interlocking of minerals and is most prevalent between the gold and pyrite and the sphalerite and pyrite. The recovery of gold is extremely important in the economic value of the ore and therefore constitutes a large part of the metallurgical problem to be solved. All of the gold is free but it has not been observed in any of the mill products except under very high magnification. Some of the gold is tarnished, and this condition also makes recovery difficult. The gold values have been determined to be highest in association with chalchopyrite and arsenopyrite. The silver occurs mostly in association with galena and tennantite. A small amount of native silver has also been observed occasionally. The galena, being softer than the other minerals, frees much better in grinding. Some oxidation of galena is present in the ore, as the nonsulphide lead content amounts to approximately 10 pct of the total lead. Some oxidation of sphalerite is also present in the ore. Microscopic examination of the zinc concentrate shows many grains in the minus 325-mesh to be half pyrite, together with the fact that some of the zinc is marmatite, makes production of a high-grade zinc concentrate very difficult unless recovery is sacrificed. In the grinding, it has been determined that the flotation feed must be maintained at 85 pct minus 200-mesh to free the minerals sufficiently to make the best economic recoveries. Table I illustrates the effect of fine grinding. It shows that the bulk of the recovered minerals is in the minus 325-mesh size and is the part of the minerals that is more readily freed. The pyrite concentrate is not given in the table because it contains practically no minus 325-mesh. DEVELOPMENT OF PRESENT FLOWSHEET AND MILLING PRACTICE The first milling operation started in 1938, with a mill capacity of 140 tons daily, producing a bulk gold-silver-lead concentrate. After several stages of expansion and changes of the mill flowsheet, the mill is currently treating 380 tons of ore daily and three separate concentrates are produced. In order of their importance and value, these are: (1) lead concentrate, (2) zinc concentrate and (3) pyrite concentrate. The present average grade of mill heads is: gold 0.11 oz, silver 4.00 oz, lead 2.50 pct, zinc 7.60 pct, copper 0.22 pct, iron 22 pet and 30 pct insolubles. Specific gravity of the ore is 3.8. During the period when bulk flotation was practiced, the flowsheet was very simple. The ore was ground fine enough to liberate as much gold, silver and lead as possible. Necessary collectors and frothers were added in sufficient quantity

Jan 1, 1947

By D. W. Fuerstenau, L. M. Berlioz

In 1957, Charles1 first presented an analysis of a relationship between the energy expended in comminution and the extent of size reduction achieved. Subsequently, Schuhmann extended and interpreted Charles' approach to comminution. According to their analysis, the energy, E, expended in comminuting unit mass of fairly uniformly-sized material is related to the size modulus of the product, k, by where a is the distribution modulus (slope of the log-log cumulative size distribution plot) and C is a constant, which is primarily determined by properties of the solid. If there is any fundamental basis for the E vs k relationship, E must necessarily be concerned with the useful work for the size reduction process and not necessarily the work input, as discussed in detail by Harris.3 Charles and numerous other investigators tested this equation only by relating k to the grinding time, assuming expended energy to be directly proportional to time, but never directly measuring power. In our laboratories, we recently constructed a special batch ball mill with which the power could be accurately determined with torque measuring apparatus.4 With this device, a direct test of the Charles relationship could then be made for ball milling. 5 EXPERIMENTAL A stainless steel mill, 11.5 in. long and 10 in. in inside diam, lined with eight low-silhouette lifter bars, was used for these experiments. The grinding media consisted of 30 kg of single sized, 1-in. diam, stainless steel balls, which occupied about 50% of the total mill volume under static conditions. The void fraction of the static ball load was approximately 0.4, and for the dry grinding conditions used, the corresponding interstitial volume was filled when about 3300 g of the dolomite feed material was present. The 7x9 mesh dolomite used as feed was obtained as a natural, uncrushed product thus as- suring a random distribution of feed particle shapes. Charge weights of 660, 1320, 1980, 2480, 3300, 3960 and 5280 g, which correspond to 20%, 40%, 60%, 80%, l00%, 120%, and 160% of the interstitial load, respectively, were used. Grinding times of 20, 40, 60, 80, 100, 150, 200 and 300 revolutions were considered, with the mill operating at 54 rpm (approximately 60% of critical speed). The tests were made sequentially, in that the size distribution obtained after a certain grinding interval was utilized as the feed for the subsequent period of grinding. Agreement with control experiments where the mill ran continuously for the entire interval was excellent. Torque measurements were made utilizing a Baldwin-Lima-Hamilton SR-4 torque pickup in the manner that has been described previously.3 Standard wet (to obtain the -400 mesh material) and dry sieving procedures were followed using the Tyler full screen series. RESULTS The Gaudin-Schuhmann size distributions obtained in all of these experiments are characterized by distribution moduli (slopes), a, of about 0.66 and are representative of normal dry batch ball milling of a material like dolomite. As an illustration of typical

Jan 1, 1968

By Louise Barton Freeman, Coleman D. Hunter

The total production of oil in Kentucky during the year 1943 reached 7,010,776 bbl., which is more than at any time since 1930. Of this total, 5,287,659 bbl. was produced from the counties west of the Cincinnati arch, 692,359 bbl. from the 18 new pools opened during the year, and 3,260,765 from the Smith Mills pool, which was discovered in August of 1942. This is an important increase in western Kentucky in spite of the low price of crude, and demonstrates effectively the desire of the industry to cooperate in meeting the increased demands made by the war. Western Kentucky Two deep tests were drilled in the Kentucky portion of the Mississippi Embayment this year. Both were drilled to test the St. Peter. One well, drilled in Marshall County by the Adams Oil and Gas Co., did not encounter any St. Peter sandstone but drilled 650 ft. of formation below the position of the St. Peter and above the true Knox dolomite. The other well, in Ballard County, was reported to have tested the St. Peter and to have been temporarily abandoned at 3069 ft. At this depth the well probably was stopped in about the same formation as the Marshall County well. No accurate information is available on the Ballard County well. Several new producing areas were added to the list of fields in the western Kentucky coal basin, in Daviess, Henderson, McLean, Ohio, Union and Webster Counties. The Smith Mills pool was enlarged and production was found in the McClosky (Ste. Genevieve) in addition to the Cypress sandstone from which much of the earlier production had been obtained. There was some interest during the year in testing the Devonian and Silurian formations in the area south and east of the western Kentucky coal basin. In the fall of 1943, a 15 to 20-bbl. well was drilled in Allen County and two more wells are now being drilled. The production was obtained from within a few feet of the base of the Chattanooga black shale, probably in the upper Silurian. One well in Simpson County was drilled completely through the Silurian section before it was abandoned. Several wells were drilled in Logan, Todd and Christian Counties to test the Devonian where it is thinned by removal of the upper formations before deposition of the Chattanooga shale. None of these wells was successful but several other locations are now being tested. The Silurian thins in like manner on the eastern flank of the coal basin as the crest of the Cincinnati arch is approached, and it is along this thinning edge that such fields as the LeGrande, Logsdon Valley, Magnolia, Bowling Green and the Barren County pools were developed. A number of wells were drilled around these old pools in an effort to extend them, some of which were successful. The wells listed this year in Larue, Hardin, Barren, Hart and Warren Counties were drilled in the search for other such fields.

Jan 1, 1944

By Walter Miller

A surprising development during the year was the continued high demand for petroleum products and the high level of crude oil charges to the stills. Generally speaking, the petroleum industry during 1946 succeeded in producing a greater quantity of crude oil and petroleum products than in any of the war years, and considerably exceeded the production of any prewar year. Daily crude still charges averaged between 4,700,000 and 4,800,000 bbl per day for 1946 and about equaled the 1945 record, although most pessimistic 1945 guesses, predictions, or fears ranged, for 1946, from only 3,900,000 to 4,400,000 bbl per day. In spite of the high crude charge to the stills, total stock of crude oil was higher at the end of the year by some 7,000,000 to 8,000,000 bbl. A similar story holds regarding stocks of the principal refined products. Gasoline on hand at year's end was two to three million barrels lower, and was considered low for the expected demand during the coming high consuming season, while stocks of light and heavy fuel oils, although some higher than a year previous, hardly reached a comfortable level. The trend in gasoline of high octane number, which has resulted in a marked rise in. the antiknock quality by the end of 1945 (five or six numbers higher than during the war and one number higher than the prewar quality of civilian motor gasoline of 1941) was abruptly arrested by an acute shortage of metallic lead for manufacturing tetraethyl lead. Government action in the form of lead price control, rationing, and the setting of octane ceiling specifications to conform to the reduced ethyl lead compound available were enforced until abrogated at the end of the year. It will be interesting to see how rapidly the octane levels will resume the rising trend, as more metallic lead slowly becomes available for making greater quantities of ethyl lead compound. As octane quality rises over present levels the disadvantage of the refiner without catalytic cracking equipment will increase. Gasoline made by catalytic cracking, without addition of ethyl lead, approximates 77 octane by the official ASTM Motor Method test, compared with 66 for gasoline generally similar in volatility made by the older thermal cracking operation. Catalytic gasoline shows an even greater improvement in the Research octane number, the comparison being roughly 86 Research versus 71 Research octane for the thermal cracked product. This higher differential in Research octane is credited by many, although not universally so, as contributing to better road performance, and consequently resulting in a more desirable product marketwise. In some parts of the country a premium of roughly one fourth cent per gallon is now being paid for gasoline with higher Research octane made possible by including catalytic cracked product in the final blends. If such price differentials in favor of catalytic gaso-

Jan 1, 1947

By John K. Hammes

INTRODUCTION From the point of view of the consumer, the cost of mineral commodities might be viewed as the total price industry pays for mine output. Similarly, the mining company engaged in the ongoing business of finding, developing and operating new mines is concerned very much today with the distribution of all the revenue paid for mine output and not just with its direct or controllable cash costs. In other words, what will the labor force, the supplier of energy, explosives, and reagents, and the supplier of government services, management, capital, and the ore reserves receive for their contribution to production? A significant amount might be categorized as what economic theory classifies as economic rent. Mining companies are finding it increasingly difficult to negotiate concession or work contracts to develop ore reserves in lesser developed countries, just as they find themselves accused of taking excess profits in their own countries. The principal difficulty in reaching mutually satisfactory agreements in many cases is the difficulty in establishing an acceptable distribution of income, in particular the distribution of economic rent. (See Chapter 7). Further, it is logical that the decisions and policies of the interested parties be they government or industry should be and will be influenced by their competitive position relative to determining the distribution of economic rent. The raising of finance for a mining project today may be inhibited by too biased an extraction of economic rent by entities other than the risk takers, the mining companies. ECONOMIC RENT A British economist (Ricardo D. McGraw-Hill, 1955) first proposed the concept of economic rent (See Drechsler, H.D. earlier in this Chapter.) Ricardo pointed out that no rent would be paid until land became scarce. Ricardo also stressed the distinction that the price of farm produce was not higher because of the rent paid on farm land but that the rent or price of more fertile farm land was higher because the price of produce is higher. This led to the concept that economic rent is not a cost and that it is therefore not price determining, but is itself price determined. Economic rent may be viewed as a cost if cost is equated with the concept of payment or distribution of income to any factor used in production. However, if it is a criterion that a payment must be made to the supplier of the factor of production, then economic rent is not truly a cost because it is not necessarily distributed or "paid" to the supplier. Consider the commodity A which occurs in three grades: Al, A2, and A3. Any grade may be used as a substitute for another grade in all of the industrial uses of A. However, in industries X and Y the different grades have different productivities. Table 1 shows the relative productivities of each grade in industries X and Y, and in all other industries [~]. [ ]

Jan 1, 1985

By William H. Spice

The fault zone of south central Texas showed renewed activity during I940 along a trend roughly paralleling the old established Balcones fault-line group of producing fields. This was a result of the new discoveries in the Wilcox (Eocene) formation in southeastern Texas and Louisiana. As of the end of the year, one new field producing from the Wilcox formation had been discovered on the Washburn ranch in La Salle County, along the southwestern limits of the district, and several projected tests into that formation were under way. In the western part of the district, par-titularly in the part of the Rio Grande embayment that is in Dimmit, Webb and Zavala Counties, there has been renewed leasing activity with the shallower sands in the Navarro-Taylor formations (Upper Cretaceous) as the objective in several projected tests for the early part of 1941. Three new fields have been discovered along the old fault-line trend, but these have been comparatively small, producing either from Dale lime, Austin chalk or Buda lime. No new fields were discovered during the Year in the Edwards (Lower Cretaceous) lime horizon. Approximately 260 wells were drilled in the district during 1940, which resulted in four new oil fields. Twenty-seven new wells were completed in the Proven Edwards lime fields of Darst Creek, Luling and Salt Flat and seven were added to production in the Pearsall field. Approximately 160 wells in 18 counties were completed as failures during the year. The district produced 7,659,634 bbl. during 1940, which was a 9 per cent decrease under production for 1939. In all, 3559 wells were producing at the end of I940, compared with 3562 wells producing at the end of the previous year; 104 new producing wells were completed and 163 wells were abandoned in the producing fields of the district. During 1940 considerable exploratory work was carried on along the Wilcox trend within the district, particularly by major companies employing various types of geophysical methods, and leasing activity increased considerably. At the end of the year, the total number of acres of nonproducing leases held by major companies in the district increased about 10 per cent. It is anticipated that this activity will continue into the first part of 1941 and will be supplemented by several exploratory test wells. New Fields B,, Creek, Caldwett County.— . R. Ogden NO. 2 Talley, discovery well of the Bee Creek field, in the northeastern part of Caldwell County, was completed on March 16, I940, in Dale lime from 2091 to 2238 ft., pumping 85 bbl. per day, 39° A.P.1. gravity. The discovery of this field can be credited to a combination of subsurface geology and magnetometer work, which indicated the presence of a serpentine intrusion. At the end of the year, ,3 producing oil wells had been completed and the field has produced a total of 47,050 barrels.

Jan 1, 1941

By Louis Ware

At the beginning of the present war, the United States faced the need to multiply its production of magnesium metal almost roo times within the shortest possible period. Urgently needed for construction of military aircraft, incendiary bombs, and other war uses, magnesium was at the top of the list of critical war materials. Up to that time only one Producer, employing Only One process and using One raw material in a single plant, represented this country's entire Production capacity. It was immediately desirable to plan a numher of plants located strategically over the Count'Y and to expand an industry more rapidly and to a greater extent than ever before had been attempted in so short a time. In '939 this American producer, the Dow Chemical .9 was making about 7 million Pounds of magnesium metal. It utilized as a raw material brine containing magnesium chloride, which was pumped from wells in Michigan. The logical ap-preach to certain increased production was to employ the same process on the same raw material in other sections of the United States. In Europe and other countries, different processes had been used and different raw materials were being utilized, but all of the skill and knowledge for production in this country was that of using the Dow type of cell and magnesium chloride as a raw material. The Government was testing other processes, but none then had been proved commercially feasible. Development OF New Process The International Minerals and Chemical Corporation had available a large quantity of magnesium ,chloride at Carls-bad, New Mexico, contained in the end liquor produced from its potash plant sillce the buildng of the plant in 1941 It was the only company mining commercially a magnesium ore and having anything like this quantity of magnesium chloride liquor. The magnesium ore, langbeinite, was being mined from the 800-ft. level for its content of potassium sulphate. This ore, a potassium magnesium sulphate, was reacted in a base exchange plant with potassium chloride to produce potassium sulphate, the discharge liquor having a high content of magnesium chloride. Three potash-producing companies are in the Carlsbad area, but only International has developed and is commercially producing the potash-magnesium ores. The lower, or No. 4, veil, in that area is potassium chloride ore, and is continuous through all the properties. The langbeinite, or No. 2, vein is minable at the International property, but occurs sparsely, if - at in other areas being mined in that vicinity. It is understood that most of the mag. nesium produced] by Germany comes from magnesium and magnesium-potassium ores obtained from potash mines. It was logical for International to pro-pose to make available this magnesium material and to offer its technical staff to design, construct and manage a magnesium plant for the account of the Government. The plan that finally was adopted by the

Jan 1, 1944

By Stanley J. LeFond, Neal Davis

Drilling an oil well or most other types of drilling or coring is no longer a simple and uncomplicated operation. Drilling today at depths which exceed 9144 m (30,000 ft) is hazardous and requires personnel with long and varied experience in drilling. It also requires extensive experience and knowledge in the use of materials which are added to the drilling fluid or "mud," more often than not materials utilizing an industrial mineral. The drilling fluid can vary from a simple mixture of water and "mud" to a very sophisticated, scientifically compounded drilling fluid. Industrial Minerals Used in Drilling Fluids Industrial minerals which are commonly used in oilwell drilling and completion are listed in Table 1. The most important minerals, determined by sales, are bentonite and barite. The other minerals listed are either used to achieve a specific purpose or are used regularly but in limited quantities. The main suppliers of drilling fluids internationally are Magcobar Div., Dresser Industries, Inc.; Baroid Div., National Lead Co.; IMC Drilling Mud Co., (a subsidiary of international Minerals and Chemicals Corp. and Halliburton Co.); and Milchem, a division of Baker Industries. Most of the industrial minerals are found in North America, with barite mines and processing plants located in Nevada, Arkansas, Missouri, and Arizona, and bentonite mines near Graybull, WY. Other mines, such as those in Nova Scotia, are capable of shipping to South America and to the European and Middle East countries. Most of the materials processed by any of the suppliers must conform to specifications set by the American Petroleum Institute (API) or the Oil Companies Material Organization (OCMA). These specifications provide for uniform physical and chemical properties of the materials to be sold on the open market. Function of Drilling Fluids In the early days of rotary drilling, the primary function of drilling fluids was to bring the cuttings from the bottom of the hole to the surface. Today it is recognized the drilling fluid has at least ten important functions: 1) To remove the cuttings from the bottom of the hole and carry them to the surface. 2) To cool and lubricate the drill string and drill bit. 3) To build an impermeable cake on the wall of the hole. 4) To control subsurface pressures. 5) To hold cuttings and weight material in suspension when circulation is interrupted. 6) To release sand and cuttings at the surface. 7) To support part of the weight of drill pipe and casing. 8) To reduce to a minimum any adverse effects upon the formation adjacent to the hole. 9) To insure maximum information about the formation penetrated. 10) To transmit hydraulic horsepower to the bit. In order to accomplish some or all of these functions while penetrating formations of various characteristics, several types of drilling fluids systems have been designed. Types of Drilling Muds There are two basic drilling fluid systems-water-base muds and oil-base muds. There is a wide variety of groups within these two main

Jan 1, 1983

By F. S. White, E. L. Kinsella

THE solids fluidization process brought out by the Standard Oil Development Co. in the early forties for catalytic cracking of petroleum enabled rapid transfer of large quantities of heat from gases to solids under closely controlled temperature conditions. As the technique developed, it was natural that applications for the process outside the petroleum industry would be sought. The calcination of limestone to ' quicklime requires the transfer of a large quantity of heat at high and closely controlled temperatures. For these reasons, this possible application was one of the first to be investigated. Laboratory work conducted by the Dorr Co. indicated that lime produced by solids fluidization would be of exceptional quality. Calculation of theoretical heat balances showed that savings in fuel could be expected. Accordingly, a pilot plant of 10 tons per day capacity was erected by the New England Lime Co. at Adams, Mass., to substantiate the process. Operation of the pilot plant, previously described,1 showed that excellent lime could be produced with a saving in fuel. The work also indicated the necessity of preparing feed to remove the finer fractions if dust losses were to be held to a tolerable level. A single-stage fluidized solids drier-stripper was developed to accomplish this sizing.2 Subsequently a commercial lime reactor was erected at Adams, beginning operation in June 1949, followed by air sizer facilities completed in November 1951. This paper will describe these two applications of solids fluidization. The raw material for preparation of lime by the fluidizing process is a high calcium crystalline lime stone having the approximate chemical composition shown in Table I. The stone is first prepared by crushing and grinding in conventional equipment to pass a 6-mesh sieve. After crushing, the material is sent to the FluoDry unit for drying and dedusting. Fluidized Drying and Sizing As shown in Fig. 1, the FluoDry unit consists of a 1/4-in. cylindrical steel shell, 9-ft ID by 22-ft 6-in. overall height. Attached horizontally at the bottom is a 6-ft diam combustion chamber, approximately 7 ft 6 in. long. A refractory constriction dome, consisting of first-quality fire brick shapes, partitions the inside into two sections. The lower section is called the windbox and the upper the bed compartment. The vertical wall of the shell is lined with 6-in. first-quality rotary kiln blocks. In the bottom of the windbox a hoppered section is formed with castable refractory to permit the windbox to be readily cleaned via a 6-in. screw conveyor. The combustion chamber is similarly lined with refractory shapes. On the 6-in. diam section, 4 1/2 in. of insulating brick, HW-26, are used. The inner combustion chamber is lined with 4 1/2-in. Korundal brick to withstand the high flame temperatures encountered. An 8-in. steel feed pipe, entering vertically through the top and fitted with an air-operated cone valve,

Jan 1, 1952

By W. E. Hess

AT the Vesta mines of Jones & Laughlin Steel Corp. on the Monongahela River, 35 miles south of Pittsburgh, JCM Joy continuous miners and 6-SC shuttle cars are used for pillar extraction in the Pittsburgh seam. The entire output of the mine goes into coke production for blast furnace operation. Because this coal, which has high metallurgical qualities, is close to the place where it is ultimately used and because supplies with these properties are being rapidly depleted, complete recovery is essential wherever possible. With the introduction of the continuous miner into the Vesta mines, therefore, it was necessary to plan a project which would facilitate development and provide for future total recovery. Use of continuous miners under varying conditions has necessitated changes with regard to roof action, method of development, method of pillar attack, and innovations in mining. In the following pages these changes will be discussed. Prior to the introduction of continuous miners the Pittsburgh seam at the Vesta mines averaged 72 in. of mineable coal, overlain with 12 to 16 in. of draw-slate, which weathers on exposure to air and is not firm enough to be held in place. Immediately overlying the drawslate is a wild or rooster coal, very irregular in thickness, varying from 12 to 30 in. Above the rooster coal the strata consists predominately of shales or lime shales and sandstone. Just before the introduction of continuous miners in the Vesta mines, however, a definite change took place in the character of the roof structure overlying the coal seam, see Fig. 1. Thickness of laminated roof immediately overlying the rooster coal varies with localities and introduces a problem in roof control. In fact, a set of eight main entries being developed in Vesta NO. 4 mine entered an area with so difficult a roof structure that management considered abandoning the section altogether. In this locality the roof consisted of thin alternate layers of roof coals and shales, with an occasional irregular seam of slick slate, the whole being laced with slips, and the coal itself being cut by clay veins and spars. In an effort to overcome some of the difficulties, roof bolting was introduced in 1949. This made it possible to recover coal from an area which otherwise would have been economically unmineable. There have been very few roof bolt failures. When conventional machines were replaced by continuous miners there were changes in the development of butt entries. By these changes it was hoped: 1—to speed development, 2—to provide as much solid coal as possible for the machine on retreat, 3—to avoid the necessity of crossing entries already driven, 4—to facilitate ventilation, 5—to provide a roadway for shuttle car haulage which would eliminate the necessity of running through doors or curtains, 6—to provide better roof control by increasing the distance between the center lines of entries, and 7—to provide more coal when the machine was in position to load.

Jan 1, 1956

By Leonard Larson

Before direct or wet smelting of copper concentrate was adopted at the McGill smelter, in November 1932, actual furnace smelting tests had indicated the possibility of smelting between 400 and 500 dry tons of wet concentrate per furnace day. Under calcine smelting practice, solid charge up to 116; tons per furnace day had been smelted. It was realized that in order to smelt wet tonnage in equivalent amount per furnace day, a higher combustion rate and higher temperatures would be necessary within the furnace. The reverberatory furnace considered in the following history of wet-smelting developments is a unit rz7 ft. long and 28 ft. 8 in. wide, inside dimensions (Fig. I). This furnace was in operation through all the years from 1934 to date. During 1933, the first complete year of direct or wet smelting, the plant was on a curtailed copper-production basis and the available concentrate tonnage to be smelted was limited. The average coal-firing rate in the reverberatory for that year was 124 tons per furnace day. This rate was lower than the average for years immediately preceding under calcine smelting practice. With this coal-firing rate, an average of 391 tons of new metal-bearing material (N.M.B.M.) was smelted per furnace day. The following year, 1934, the coal-firing rate was increased to 139 tons and the smelting rate increased to 448 tons N.M.B.M. per fur- nace day. In succeeding years production required that either more tonnage be smelted in the one furnace or an additional furnace be placed in operation. With this situation confronting the smelting department, it was determined to continue the program of increasing the coal-firing rate and also to intensify the temperature in the smelting zone of the furnace. In order to accoinplish this, various improvements were made to aid combustion within the furnace. The burners were enlarged, increased primary air was supplied to the burners, and changes were made in the furnace to enlarge and streamline the outlet, thus increasing the furnace draft. The coal-firing rate was increased yearly until 1937 when the firing rate averaged 210 tons per furnace day. Thereafter the firing rate fluctuated according to character of charge and production requirements. In general, however, with the same character of charge the smelting rate increased in almost direct proportion to the increases in firing rate. Table I shows the average coal-firing rate, smelting rate, and other pertinent data for the direct-smelting years of 1933 to 1939 inclusive, the first fivc months of 1940 and May 1940. These figures show that the water evaporated in the waste-heat boilers was in almost direct proportion to the coal-firing rate. In making comparisons in the table, it should be borne in mind that the figures, except for May 1940, are yearly averages. Because of changes in character of charge or operating conditions, records for individual days or even months

Jan 1, 1944

At all business meetings of the Institute the President, or, in his absence, the First Vice-President, or, in the absence of both of them, any other Vice-President or Director, chosen by the meeting, shall preside. At all other meetings of the Institute the President, or, in his absence, one of the Vice-presidents shall preside. If none of these be present the meeting shall elect a Chairman. The President shall do and perform such other duties as may from time to time be assigned to him by resolution of the Board of Directors of the Institute. II. ORDER OF BUSINESS. At each business meeting of the Institute the order of business shall be as follows: 1. Reading of minutes of preceding meeting. 2. Report of the President. 3. Report of the Treasurer. 4. Report of the Secretary. 5. Election of Directors. 6. Reports of Standing Committees. 7. Reports of Special Committees. 8. Special Orders. 9. Miscellaneous business. This order of business may be changed at any meeting, by a vote of a majority of the Members and Associates present. At all sessions of the Institute, other than business meetings, the order of proceedings and the time of adjournment shall rest in the discretion of the presiding officer. III. SECRETARY OF THE INSTITUTE. The Secretary shall keep a record of the proceedings of all the meetings of the Institute, He shall be custodian of the corporate seal, of the minute books and of all the legal documents belonging to the Institute. He shall have charge on behalf of the Institute of all correspondence. He shall notify all Officers and Directors and all members of committees of their election and appointment; shall issue notices of all meetings of the Board, and of the annual and other business meetings of the Institute; and shall, in calling special meetings of the Directors, specify the objects of such meetings. He shall act as clerk at all the meetings of the Board of Directors and at all meetings of the Institute. The Secretary shall be custodian of all technical or scientific papers submitted to the Institute for its consideration and shall have general charge and supervision of the editing and proof-reading of all material published by the Institute, and of the distribution thereof. The Secretary shall be the custodian of all back numbers of the Transactions and other publications of the Institute. There shall be kept under his direction an account in ledger form of all such back numbers. He shall on the first day of January of each year submit to the Library Committee a statement of the number of copies of Transactions, magazines and other publications printed during the preceding year, giving the number distributed and remaining undistributed; also a statement covering additions to and withdrawals from the total stock of Institute publications, with the number remaining on hand at date of statement.

Jan 1, 1928

By J. D. Sullivan, Chester R. Austin, J. L. Nunes

It is characteristic of most shales and surface clays that a bloated or vesicular structure is produced by burning to a sufficiently high temperature, usually about 150° to 200°F. above the normal maturing temperature used when making common brick of the same material. Early investi-: gators recognized this phenomenon and attributed it to the release or expansion of gases in the vitrified piece. A number of theories have been advanced on the source of the gas and the manner in which it is evolved, but none has been proved conclusively. T. E. Jackson's1 early theory that bloating was due to oxygen evolved by ferric oxide in forming ferrous oxide or ferrous silicate was never substantiated by - experimental work. Orton2 thought this explanation unlikely, as all clays should bloat at the same temperature, if this were true. He found that clays bloated in the range from IIoo° to 17oo°C. Also, many clays containing iron did not bloat at all, but fused. Orton also stated that oxida- tion of different types of carbon was a source of gas during burning of clay and should be expelled before vitrification was reached. Seger3 said that he had dissolved ferric oxide in glass with no apparent evolution of gas. Matson4 came to the conclusion that ferruginous clays burned ' to vitrification in an oxidizing atmosphere did not have the iron in a ferrous form. According to Wilson,= the gases responsible for bloating might be entrapped air, water, sulphur dioxide, carbon monoxide, oxygen, and hydrocarbons. He spoke of two causes of bloating: (I) incomplete oxidation below the vitrification temperature, and (2) decomposition of compounds and evolution of gases above the vitrification temperature. Decomposition of calcium sulphate was given as the principal example of the latter. Bleininger and Montgomery0 stated that if any time after vitrification began the evolution of gaseous matter was rapid enough so that pressure was produced within the clay, bloating was certain to take place, and a vesicular structure would be formed. They recognized that initial structure, rate of heating, kiln atmosphere, and many other variables affected bloating. Work done by the Emergency Fleet Corporation7 indicated that clays suitable for bloating should be high in compounds of metallic oxides, carbon, sulphur, sodium, potassium, or other equivalent compounds, which either act as a flux or give off gas. Orton2 studied the chemical status of the carbon, iron, and sulphur in clays during various stages of burning, using a Huron shale that bloated under oxidizing or reducing conditions. He found that only a small amount of sulphur remained in the clay and that it could be detected only by dissolving the clay in hydrofluoric acid; i.e., the sulphur was in combination with the silica. orton said that this sulphur was probably in the form of iron sulphide dissolved in the glass phase. The iron sulphide was not broken down by heating, but was dissolved in the basic slag or glass,

Jan 1, 1942

By James F. Watson, Jack L. Christian

The austenite to martensite solid state phase transformation in the 300 series austenitic stainless steels was studied over the temperature range of 788° to -423°F. The primary variables controlling this transformation are temperature, plastic strain, and chernical composition. Consequently, temperature effects were studied by measurements at 78", -100°, -320°, ad -423°F; plastic strain was controlled by cold-rolling the alloys varying amounts between 40 and 80 pet; and chemical compositions were varied by using 301, 302, 304 ELC, and 310 stainless steel alloys which exhibit varying degrees of austenite stability. The martensite contents of various alloys were correlated with several mechanical properties including yield and ultimate tensile strength, elongation, and notched tensile strength (Kt = 6.3). The yield and tensite strengths generally increased with increasing martensite content, but ) no correlation was observed between elongation and martensite content. The notched/un-notched ratio (Kt = 6.3) at -423°F exhibited a maximun at about 65 pct martensite. Attempts to correlate austenite stability (as measured by the Ms temperature) with both martensite content, and incremental increases in martensite content resulting from tensile testing were generally unsuccessful because the variable of cold Work could not be separated. As a result, only a general correlation of these variables was obtained. A (111) pole figure of austenite in a cold-rolled 301 stainless steel mas prepared an attempt to further investigate directionality as exhibited by mechan- ical properties. Yield strength was correlated with this pole figure, but ultimate and notched tensile strengths were not. 1 HE literature contains a wide variety of references pertaining to the austenite to martensite solid state phase transformation in austenitic stainless steel, see references 1 through 18. Discussions of the crystallography and kinetics of this transformation are given in references 2, 7, 8, 'and 11, while further discussions of austenite stability and hardening mechanisms are given in references 1, 3, and 10. Two important processing variables involved in this reaction are the degree of cold work and the temperature at which cold work is performed, and the nature of these effects are outlined in references 4 and 12, and 15 and 16 respectively. The latter two references deal primarily with cold rolling conducted at subzero temperatures. The effect of chemical composition on the austenite to martensite reaction was treated in detail by Eichelman and Hull, and they determined an equation for the M, temperature of this type of steel which included the effects of nickel, chromium, carbon, nitrogen, silicon, and manganese.5 Previous studies have shown that austenitic stainless steels of AISI types 301, 302, 304ELC, 310, and 301-N exhibit mechanical properties between 78" and -423"~ that are microstructure dependent, and the dependence of this microstructure on chemistry, temperature, tensile stress, and prior deformation is in general accord with previous investigations which have measured the effects of each of these variables on structure, or more specifically, the austenite-to-martensite transformation.lg The behavior of fully stable alloys, such as ATST type 310, at cryogenic temperatures is

Jan 1, 1962

By E. A. Gulbransen, W. S. Wysong

The behavior of tungsten and its surface oxides in oxidizing and reducing atmospheres and in high vacua at elevated temperatures is a question of considerable technical importance. The use of tungsten as a a Or as an important component in alloys in high temperature Oxidizing atmospheres has been limited because of the unprotective nature of its oxide film and the volatility of its oxide. This paper will present results of a micro-balance study of the following problems: (1) the oxidation behavior in the ternperature range of 25 to 550°C (') the reduction with pure hydrogen Of thin Oxide films formed On tungsten, and (3) the volatility Of thin Oxide films On tungsten. Tungsten is an interesting metal to study for the following reasons: (1) although the Oxide to to ratio is greater than one, the oxide is not considered protective, ('1 the meta1 readily Oxidizes at temperatures from 30" to 55o°C (3) the oxides WO² and WO³ are reduced at temperatures as low as 500°C. by hydrogen, and (4) the Oxide WO3 is volatile at temperatures from 800 to 1100°C. Literature The oxidation of tungsten in its thin film range has not been studied critically. In the thick film range Dunn3 has made the only systematic study. He found the oxidation rate to obey the parabolic rate law in the temperature range of 700 to 900°c. The temperature variation of the oxidation rate constant was found to follow an exponential law of the Arrhenius type. An inflection was noticed in the temperature plot of the rate law constant at 850 to 900°C. This was attributed to a phase change in the oxides, Schei14 has studied the oxidation rate at 500 and 700°C over long periods of time and found a linear rate law. This result was interpreted as evidence for the presence of a nonprotective film. Pilling and Bed-worth's5 analyses of the oxide volume to metal volume ratio would indicate that a compact protective film should form. McAdam and Geil6 have studied the oxidation of tungsten in the thin film range using the interference color method. A parabolic rate law was found. Their curves showed that tungsten oxidizes faster than nickel but more slowly than iron. The lattice structures found in the oxidation of tungsten surfaces have been studied by Hickman and Gulbransen.? They have reported that WO3 is the stable oxide in contact with the metallic substrate up to approximately 600°C while wo³ forms first at 7oo°c. Hagg and Magneli8 have recently reported a study of the lattice structures . observed in the tungsten oxidcs using the X-ray diffraction method. In addition to an a-phase WO3 and a '-phase WO2, they reported the existence of two new phases. A 8' phase, homogeneous between

Jan 1, 1949

By J. D. Sullivan, Chester R. Austin, J. L. Nunes

It is characteristic of most shales and surface clays that a bloated or vesicular structure is produced by burning to a sufficiently high temperature, usually about 150° to 200°F. above the normal maturing temperature used when making common brick of the same material. Early investi-: gators recognized this phenomenon and attributed it to the release or expansion of gases in the vitrified piece. A number of theories have been advanced on the source of the gas and the manner in which it is evolved, but none has been proved conclusively. T. E. Jackson's1 early theory that bloating was due to oxygen evolved by ferric oxide in forming ferrous oxide or ferrous silicate was never substantiated by - experimental work. Orton2 thought this explanation unlikely, as all clays should bloat at the same temperature, if this were true. He found that clays bloated in the range from IIoo° to 17oo°C. Also, many clays containing iron did not bloat at all, but fused. Orton also stated that oxida- tion of different types of carbon was a source of gas during burning of clay and should be expelled before vitrification was reached. Seger3 said that he had dissolved ferric oxide in glass with no apparent evolution of gas. Matson4 came to the conclusion that ferruginous clays burned ' to vitrification in an oxidizing atmosphere did not have the iron in a ferrous form. According to Wilson,= the gases responsible for bloating might be entrapped air, water, sulphur dioxide, carbon monoxide, oxygen, and hydrocarbons. He spoke of two causes of bloating: (I) incomplete oxidation below the vitrification temperature, and (2) decomposition of compounds and evolution of gases above the vitrification temperature. Decomposition of calcium sulphate was given as the principal example of the latter. Bleininger and Montgomery0 stated that if any time after vitrification began the evolution of gaseous matter was rapid enough so that pressure was produced within the clay, bloating was certain to take place, and a vesicular structure would be formed. They recognized that initial structure, rate of heating, kiln atmosphere, and many other variables affected bloating. Work done by the Emergency Fleet Corporation7 indicated that clays suitable for bloating should be high in compounds of metallic oxides, carbon, sulphur, sodium, potassium, or other equivalent compounds, which either act as a flux or give off gas. Orton2 studied the chemical status of the carbon, iron, and sulphur in clays during various stages of burning, using a Huron shale that bloated under oxidizing or reducing conditions. He found that only a small amount of sulphur remained in the clay and that it could be detected only by dissolving the clay in hydrofluoric acid; i.e., the sulphur was in combination with the silica. orton said that this sulphur was probably in the form of iron sulphide dissolved in the glass phase. The iron sulphide was not broken down by heating, but was dissolved in the basic slag or glass,

Jan 1, 1942

By V. C. Perini

The 1943 designation of districts for the Transactions† has caused some confusion because of the elimination of the West Central Texas district and the allocation of the counties of this district to the North Texas district and the North Central Texas district. The North Central Texas district as herein defined includes the counties of Brown, Callahan, Cole-man, Comanche, Coryell, Eastland, Erath, Fisher, Hamilton, Hood, Jones, Lampasas, Mills, Nolan, Palo Pinto, Parker, San Saba, Shackelford, Stephens, Stonewall, Summerville, Taylor, Throckmorton and Wise. These counties as listed are the counties of District 7B, State Railroad Commission. This district covers the south central crest and the west flank of the Bend flexure north of the Llano uplift. The west flank of the Bend flexure is on the east boundary of the Permian Basin of West Texas. The North Texas district, District No. 9, State Railroad Commission, includes the counties of Archer, Clay, Cooke, Foard, Hardeman, Jack, Knox, Montague, Wichita, Wilbarger and Young. The area of this district covers the crest and south flank of the Red River uplift and the north central crest of the Bend flexure. The greater part of the oil and gas produced in the past from the North Central Texas district has been from Pennsyl-vanian strata. Some oil and gas has been produced from the lower Permian (by the latest selection of the Pennsylvanian-Permian boundary') and minor amounts from the Mississippian and Ordovician sediments. Increasingly important quantities of oil and gas are to be expected from the older sediments by deeper development in proven fields and by new discoveries. Most of the oil and gas in the district has accumulated in localized, well-defined structural traps in limestone and sandstone reservoirs and in traps due to stratigraphic changes in sedimentation, mainly porosity traps in limestone and sandstone lenses, both usually associated with some structural feature. The Stripper Well Premium Plan as adopted by the office of the Federal Price Administrator has been an aid to the producers of stripper wells. The producers are pleased to receive the subsidy to prolong the plugging of wells, but they are not too pleased with the subsidy plan in principle. Most independent operators are in favor of, and think they are entitled to, an increase in the market price for oil. The price is not adequate to meet the requirements of the average independent operator with the continued advance in production, development and wildcatting costs. Old and new pipe lines for oil and gas leading out of the state are removing reserves at an alarming rate. Curves showing the rate of discovery versus production and pipe-line deliveries in and out of the state make a cross that sooner or later will be fatal to the state. Wildcatting not only needs a price increase but every other available incentive and encouragement.

Jan 1, 1945

By Kenneth C. Vincent, A. M. Gaudin

TEN years ago Taggart, Taylor and Ince1 described a workable, convenient apparatus for the measurement of contact angles between cleaved, ground or polished particles and captive bubbles. Wark and Cox2 and Wark and Sutherland3 have done an immense amount of experimental work with this apparatus. Their work has had as principal object the determination of "contact curves." Contact curves are cartesian charts in which pH (or some other variable) is plotted against quantity of modifying agent. The rectangular area is broken into two or more curvilinear areas separated by the contact curve. The curve indicates that a sharp demarcation exists between conditions that bring about sticking of particles to bubbles and conditions that do not produce sticking. The type curve appears in the TRANSACTIONS as Fig. 1, page 248, volume 112. Wark and Cox offer data to show that the contact angle has a value determined by and characteristic of the agent used. Wark and Cox also make the statement that they believe this value is independent of concentration (ref. 2a, p. 209). They say: It is suspected that, given sufficient time and provided that there are no disturbing factors, the full ethyl xanthate angle (corresponding to a complete xanthate film) would be obtained in every case where contact occurs. Such a conclusion, if correct, would tend to substantiate the hypothesis of flotation collection by metathesis championed by Taggart and his associates4-8 and would argue against the adsorption hypothesis now adopted by Wark7 and by one of us.8 However, the data of Wark and Cox do not bear out the conclusion that there is a sharp passage from conditions of contact to conditions of noncontact. Rather, they indicate the existence of a transition zone of reagent concentration across which the contact angle varies with changes in reagent concentration from zero to a value near the maximum. This may be seen, for example, from Fig. 195 in the new text by one of us (ref. 8, p. 380), which presents the data of Wark and Cox in graphical form. The object of this study has been to explore the nature of the transition from conditions of contact to conditions of noncontact. The data of Wark and Cox to which reference has been made as showing that a gradual transition exists are marred by the fact that the region of critical-agent concentration is at an extremely small concentration. This condition suggests that diffusion may have played such a preponderant role that equilibrium was not reached within the time alloted. In the Wark and Cox data, the critical concentration was at about one part of xanthate per million parts of water. To form a monolayer of xanthate on the mineral surface would therefore require depletion of xanthate in the liquid to a depth of the order of

Jan 1, 1940

By J. B. Clemmer, F. D. DeVaney, H. A. Doerner

PRODUCTION of magnesium metal in the United States during the past decade has increased from less than 6oo,ooo lb. in 1928 to more than 4,800,000 lb. in 1938.1 The growing industry has stimulated interest in methods of production and in sources of raw material. All of the present domestic production is from brines. However, the availability of large tonnages of magnesite in the state of Washington, together with the possibility of cheap power, have created interest in the utilization of magnesite for the production of magnesium metal as well as for other purposes. Magnesite, the carbonate of magnesium (MgCO3), usually is associated with limestone (CaCO3) and dolomite (MgCO3CaCO3). It occurs in crystalline and microcrystalline (sometimes termed amorphous) forms.2 The more common crystalline mineral is found in various shades of white, gray, yellow and brown, the colors being due to impurities, chiefly iron. Magnesite has a hardness of 3.5 to 4.5 and a specific gravity of 3.0 to 3.1. It forms rhombohedral crystals in the hexagonal system, having a vitreous, pearly luster. The quarries and mines of the Northwest Magnesite Co. near Chewelah, Wash., are large producers of magnesite for refractories. The deposits are extensive, some veins being hundreds of feet wide. The boundaries of the veins are indefinite, and the magnesite is interfingered with dolomite. Calcite, talc, serpentine, quartz and shale are disseminated through the deposits. The quality of the ore cannot be determined by appearance or by simple tests; chemical analysis is required. These features make it difficult to determine the boundaries or total quantity of workable ore.3 Only the higher-grade ores are mined, and a considerable proportion of the magnesite content is discarded by hand-sorting and log-washing methods. After calcining, the sorted product meets the specifications for usual refractory material, as it contains approximately 81 per cent MgO, 7 per cent Si02, 6 per cent CaO and 6 per cent Fe203 + A1203. A sample of the reject material had the following analysis after calcining: 65.4 per cent MgO, 6.3 CaO, 21.1 Si02 and 6.5 R203. The percentage reported as R203 includes compounds whose chlorides are acid-soluble but give precipitates in ammoniacal solution that are ignited and weighed. The more common constituents are Fe203, A1203 and Ti02. The sorted magnesite product is not the best grade, even for refractory purposes, and leaves much to be desired for a reduction process. The rejected material contains a large proportion of magnesite. It is apparent that an effective concentration method would yield a higher recovery and a better product. In general, the refractory grade is not suitably pure for other uses. Recent developments in the production of

Jan 1, 1940