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By Wayne D. Gould

Cities Service Co.'s Pinto Valley concentrator was designed to eliminate excess capital costs without loss of efficiency. The result is a workable plant with some important innovations. These innovations, the equipment used, and plant processes are outlined. Particular attention is paid to the work efficiency and wear of the six ball mills, the largest wet ball mills made. For experiment purposes, four designs of liners were installed. The effectiveness of each design is discussed.

Jan 1, 1977

By Brahm Prakash, R. Schuhmann

Chemical conditions for flotation and nonflotation of quartz with oleic acid as collector and barium, calcium, aluminum, iron, and tin as activators were studied using a simple vacuum-flotation technique in glass-stoppered graduates. The detailed study of barium activation led to an interpretation based on ideal Langmuirian chemisorption.

Jan 5, 1950

By Rex T. Ellington

The fluidized bed is an effective method for investigating retorting phenomena and possibly a commercial means of retorting oil shale. Both were examined by Sinclair Oil (now part of Atlantic Richfield Co.) in the period 1965-1698. The results of the work show that the presence of an oxidizing environment during retorting results in loss of oil yield which indicates that vapor phase oil burns in preference to combustion of coke on spent shale. Consideration of hardware indicates that there are several possibilities for commercial embodiment. As a companion to shaft-type retorts the fluidized bed could have good potential. Realistic assessment of costs suggests that further development may have to wait commercialization of another process.

Jan 1, 1974

By Francis B. Foley

THE casting of steel in large molds brings into play all of the undesirable effects that result inevitably from slow cooling. The origin of the molten metal, whether basic or acid open hearth or electric furnace, has little if anything to do with the phenomena involved. If the quantity of molten metal to be cast in a single mold is large enough, there is very little one can do about it-the metal will cool so slowly that 'nothing one can do, other than to provide as good feeding as practicable from an adequate reservoir of metal in the sink head, will be of any avail. Recently we have had occasion to cast a 108-in. octagon ingot weighing 545,700 lb, necessitating the combining of metal from three 100-ton open-hearth heats. This is one of the largest ingots ever made. The body of the ingot weighed 448,800 lb, which includes a bottom pool of about 7500 lb of metal, and the sink-head weight was 96,900 lb, or about 18 pct of the total weight.

Jan 1, 1947

By M. R. Hoover, J. H. Kim, S. J. Kloda, R. E. Carmola

Feed preparation circuits, which involve such unit processes as size reduction, classification, and beneficiation are inherently a capital and operating cost intensive part of synthetic fuels plants. These circuits, as encountered in similar minerals industry operations, have until now been designed more or less by individual experience and preference mainly because of the large number of variables involved. As a first step towards a computer-aided design tool, a flowsheet simulator has been developed based on an executive program which can connect and drive modular subroutines according to the proposed circuit. The most efficient and appropriate mathematical models were selected as modular sub- routines among available sources such as SPOC, ASPEN, and DOE. Advantages and limitations of this kind of approach are discussed from the system architecture and methodology transfer standpoints with special emphasis on synfuels circuits.

Jan 1, 1983

By John G. H. Crump, E. W. Owen, Peter P. Gregory

.Although oil Production in West Texas in 1939 reached the highest figure for any year since the inauguration of proration, drilling activity continued in the decline that had commerlced the previous year. Production totaled 79,469,341s bbl. of oil during 1939 as compared with 71,257,541s bbl. in 1938 and 75,743,000 in 1937. The number of wells completed in 1939 was 1850, compared with 2045 in 1938 and 2806 ill 1937. Several factors combined to cause the decrease in drilling activity, principally the contiriued increase in the length of time required to obtain a return of invcstment and the scarcity of important new discoveries during the past two years. Of the 1850 completions 1638 resulted in oil wells, 4 were gas wells, 168 were dry holes and 40 were abandoned locations; 1990 new locations were made during the year. The ratio of dry holes to producing wells completed was one dry hole to each 9.75 oil wells, compared with one dry hole to each 7.48 oil wells completed during 1938. This large decrease in dry holes was due to a marked decline in the number of wildcat wells drilled, there having been only 120 wildcat completions during 1939. In addition to the lessened exploration work, the deeline' in activity was largely accounted for by the slowing up of operations in the older pools of Ector, Howard and Winkler Counties. Ector County, which had led West Tcxas in 1938 with 622 new oil wells, furnished only 485 producers in 1939, but was still the leader for the West Texas district. The largest gain in activity was in Yoakum County, whew 350 oil wells were completed in the Denver-Wasson field against 152 during 1938. Most of the older oil fields have been almost completely drilled up, only a few new producers still being completed from time to time in

Jan 1, 1940

The American Institute of Mining Engineers, the second of the four great national engineering societies established in the United States, was organized in 15,71. Its membership is composed of men engaged in the different branches of mining, metallurgy, geology, and chemistry. It includes both those who have worked their way up from the ranks and graduates from mining schools and universities, and at all times has counted in its membership leading technical educators. By a letter ballot of the members of the Institute, it was voted, at the annual business meeting of the Institute on February 18, 1919, to change the name of the American Institute of Mining Engineers to the American Institute of Mining and Metallurgical Engineers. The vote for the amendment to the Constitution making this change was a heavy one for such matters. It is the consensus of opinion that this marks an epoch in the history and usefulness of this Institute, and it is expected that the change will presage a large and healthy growth in metallurgical fields. Many metallurgists who knew nothing about min¬ing were loath to join a society of mining engineers, despite the fact that over 35 per cent. of the papers published in our Transactions during the past five years have dealt with metallurgical subjects.

Jan 1, 1923

By W. E. Ruder

Considerable interest has been shown lately in various types of furnaces for the production of high temperatures, both for laboratory purposes and for small industrial uses. Dr. J. A. Harkerl described certain modifications of the Arsem graphite resistance helix for high-temperature work at the National Physical Laboratory. Dr. Northrup also has developed two interesting forms of high-temperature furnaces. In 1911, Messrs. Winne and Dantsizen2 described two forms of resistance furnaces using ductile molybdenum or tungsten as resistors. Since the discovery, by this laboratory, of methods for producing these metals in ductile form, their use as resistance elements in the research laboratory of the General Electric Co. has grown to such an extent that they are now almost indispensable. These furnaces are used here for alloy research, annealing, heat-treating, and practically all of the thermal processes requiring temperatures above 900' C. Various types of furnaces have been developed to meet the general needs of laboratory work, and it is the purpose of this paper briefly to describe some of these furnaces. A tubular furnace wound with a metallic resistor is the simplest type to construct, and almost every laboratory has made such furnaces. The only essential difference between a furnace wound with platinum o base metal and one wound with tungsten or molybdenum is that the coils of the latter must be heated in a neutral or reducing atmosphere It has long been our custom here to build our resistance furnaces with : metallic casing from which the tube could be easily removed for rewind ing. The heat-insulating material—usually calcined magnesia, alumina silica, or silex, depending upon the nature of the resistor-—is used i: powdered form so that it can be readily removed and replaced. I order to adapt this method to tungsten or molybdenum windings,

Jan 1, 1918

The first of a series of special war meetings of the New York Section of the American Institute of Mining Engineers held on the evening of July 20 at the Machinery Club, preceded by an informal dinner. The subject for discussion was the important general one of the manganese supplies of the steel industry of the United States. It had been intended to include chromium supplies but this matter was crowded out and left for a later meeting. The principal speaker of the evening was Donnel F. Hewett of the U. S. Geological Survey, who, as a result of his recent studies of the resources of the country, ably presented the question of the extent to which the United States can furnish manganese ore.

Jan 9, 1917

By Earl Bardwell

IN his paper entitled, Development of Hindered-Settling Apparatus, Dr. Richards has related the history of the development of the hindered-settling classifier and given illustrations of the several types of this apparatus which lie has designed.1 An earlier paper,2 Close Sizing Before Jigging, shows the nature of the hindered-settling phenomenon and the results which it produces. In the first-mentioned paper Dr. Richards describes the method of getting hindered settling and shows the relation that the constriction bears to the classifier. The question of proper ratios between the area of the sorting column and the area of the constriction opening Dr. Richards leaves open, aside from certain statements as to the ratios which have been found to give good results in practice. While working with a hindered-settling classifier of the type now in use at the Boston & Montana Reduction Plant of the Anaconda Copper Mining Co. a number of interesting facts were brought out which have thrown considerable light on the question of proper ratio between the area of the sorting column and the area of the constriction and which will be made the subject of this paper. Free and Hindered Settling. -If a, mineral particle be dropped into a vessel containing still water, the particle will sink in accordance with the laws of free settling in water, which are as follows: 1. Of two grains having the same specific gravity but differing in size, the larger will settle in still water at the greater velocity. 2. Of two grains having the same size but differing in specific gravity, the heavier grain will settle at the greater velocity.

Jan 8, 1913

By William G. Schultz

Sylvite’s potash mine probably ranks as one of the most highly mechanized and automated mining operations in the world. Employing, on a normal 10-hr production shift, one supervisor and a crew of seven operators, Sylvite is able to mine at an average rate in excess of 600 tph. The ore is produced by two Marietta miners weighing 258 tons, making them the largest and heaviest piece of equipment ever taken underground. The ore produced by these two Marietta miners is conveyed to the shaft area, cycled through a 15,000 ton storage system and hoisted to surface completely automatically. The operation of all equipment in the mine can be monitored and controlled from a central control panel located underground.

Jan 7, 1972

By Richard F. Down

The Tynagh mine of Irish Base Metals Ltd., a subsidiary of Northgate Exploration Ltd., of Toronto, Canada, is situated one mile from the village of Tynagh in County Galway, one of the western counties of the Republic of Ireland. Mining has been carried on in Ireland since the Bronze Ages, but, apart from a reference in the 1859 Geological Survey records to much earlier mining attempts, mining has not been a feature of the Tynagh area in recent times. The present ore body was discovered by geochemical techniques in 1961. Following a diamond drilling programme to delimit the orebody, a pilot plant was operated at the property in late 1963 and early 1964. Construction of the 2000 tons per day treatment plant began later in 1964 and production commenced in December, 1965. The orebody contains both sulphide and 'oxide' ores and these are treated to produce, by flotation, a variety of lead concentrates, a zinc concentrate, and a bulk lead-zinc concentrate, which are shipped to several European smelters. The term "oxide ores" is used here to mean all ores which contain economically important amounts of the oxidised minerals of lead, zinc or copper. THE ORE The ore body lies on the northern side of a major east west fault between sandstone and limestone; it is a boat shaped mass of residual or secondary ore lying over primary sulphide in limestone. (1) (2) The secondary ore consists of both residual sulphides and

Jan 1, 1970

By E. W. Owen, John G. H. Crump, Peter P. Gregory

.Although oil Production in West Texas in 1939 reached the highest figure for any year since the inauguration of proration, drilling activity continued in the decline that had commerlced the previous year. Production totaled 79,469,341s bbl. of oil during 1939 as compared with 71,257,541s bbl. in 1938 and 75,743,000 in 1937. The number of wells completed in 1939 was 1850, compared with 2045 in 1938 and 2806 ill 1937. Several factors combined to cause the decrease in drilling activity, principally the contiriued increase in the length of time required to obtain a return of invcstment and the scarcity of important new discoveries during the past two years. Of the 1850 completions 1638 resulted in oil wells, 4 were gas wells, 168 were dry holes and 40 were abandoned locations; 1990 new locations were made during the year. The ratio of dry holes to producing wells completed was one dry hole to each 9.75 oil wells, compared with one dry hole to each 7.48 oil wells completed during 1938. This large decrease in dry holes was due to a marked decline in the number of wildcat wells drilled, there having been only 120 wildcat completions during 1939. In addition to the lessened exploration work, the deeline' in activity was largely accounted for by the slowing up of operations in the older pools of Ector, Howard and Winkler Counties. Ector County, which had led West Tcxas in 1938 with 622 new oil wells, furnished only 485 producers in 1939, but was still the leader for the West Texas district. The largest gain in activity was in Yoakum County, whew 350 oil wells were completed in the Denver-Wasson field against 152 during 1938. Most of the older oil fields have been almost completely drilled up, only a few new producers still being completed from time to time in

Jan 1, 1940

By C. G. Dunn, J. L. Walter

A study has been made of the nature of the slow growth or nucleation stage of secondary recrystallization to the cube texture in sheets of high-purity 3 pct SiFe. Cube-oriented nuclei were identified and their growth observed, using surface markings together with micrographic and X-ray techniques to provide information on grain boundary interactions and the driving forces for growth. FACTORS that promote growth of certain grains during the early stages of secondary recrystallization have been considered theoretically1 but have been little explored in a direct experimental way. In certain cases,2'3 it has been reported that the primary recrystallization grains (nuclei), which eventually become secondaries, were found to be larger than the other grains into which they grew-Factors such as grain boundary "mobility" and differences in strain energy may contribute to the

Jan 1, 1961

By W. R. Wawersik, A. M. Starfield

The classical approach to room-and-pillar mine design in flat-lying, tabular ore bodies limits itself to the special case of an extensive and uniform system of pillars. Each pillar is then assumed to carry the same load, and this load is readily calculated from the extraction ratio e and the weight of the overburden : average pillar stress = [ ] where H is depth below surface, p is average density of overburden, and g is acceleration due to gravity. The average pillar load does not, in this case, depend on the mechanical properties of either the pillars or the surrounding rock mass. The only relevant physical property of the pillars is their compressive strength, (i.e., the maximum load-carrying ability) and the criterion for design is that the average pillar stress should not exceed this strength. The wider the pillar, the greater its strength, and the design of the system is concerned with reconciling this increase in strength to the requirements of roof control so as to optimize extraction.l Any departure from a uniform distribution of pillar loads invalidates the classical approach. Such departures may, for instance, be brought about by: (1) a nonuniform layout of pillars and remnants resulting from selective mining, (2) variations in geology which result in gross changes in the properties of part of the seam or the host rock, (3) deliberate use of abutment support in narrow panels, and (4) the use of yielding pillars for local roof support in conjunction with barrier pillars to carry the overburden load.

Jan 1, 1972

By Joseph Jensen

FROM Aug. 31, 1937, until Apr. 30, 1939, there were 40,872,610 bbl. of oil run to storage in California; from Apr. 30, 1939, to Aug. 31 of the same year 5,512,912 bbl. were withdrawn from storage. But from Aug. 31, 1937, to Aug. 31, 1939, the number of producing wells in the state has increased from 17,706, with a potential production of 1,323,202 bbl., to 18,910, with a potential of 2,302,282 bbl. Thus, in a period of two years, during the first 20 months stocks increased over 1/3 and during the following four months stocks decreased 1/30. In the same two years the number of productive wells increased 1/15 and potential increased 3/4. Undoubtedly, the large increase in stocks created the pressure that caused the reduction in stocks that followed; yet this has come about in spite of the larger number of wells and higher potential. Cause of the change was the adoption on May 17, 1939, by the Central Committee of California Oil Producers of a uniform method of oil curtail-ment for all wells throughout the state. Acceptance of the method in the four months following adoption by practically all fields in California indicates that producers generally are convinced of its merit and fairness. True, some operators still overproduce, but the restraint practiced by the remainder of the industry has been sufficient to turn a situation headed for chaos into one of reasonable stability. Credit for this change goes to the industry itself, because it has all been accomplished under voluntary oil curtailment.

Jan 1, 1940

By C. Pin, J. Bruce Wagner

In order to demonstrate the role of defect chemistry in the solid state to a process-metallurgy reaction, laboratory experiments were carried aut to remove copper from liquid lead using lead sulfide which had been doped to provide definite concentrations of cation vacancies. The removal of copper decreases in the order: bismuth- or antimony-doped PbS, undoped PbS or tin-doped PbS, and silver-doped PbS. The data are explained using the simple mass -action law and in terms of the exceedingly rapid interstitial diffusion of coppw in PbS to vacant cation sites. Results are in agree-ment with thermodynamic predictions and certain industrial practices that copper may be removed from lead below the limit of its coexistence with pure Cu,S and pure PbS. The role of defects in solids has been exploited in semiconductors and many device applications, in explaining tarnish formation, dissolution rates, and mechanical properties. The application of these principles to many process-metallurgical problems has not received as much attention. It was the purpose of this study to illustrate the role of defect structures of solids in a process-metallurgical application. When lead is refined, the ore, galena (PbS), is reduced by a series of operations to liquid lead (lead bullion) containing impurities such as copper, bismuth, antimony, arsenic, and silver depending on the original composition, the fluxes added, and the particular type of operation, see Fig. 1. In order to produce a pure lead, a series of refining operations are carried out. A typical lead-bullion analysis before drossing is shown in Table I. Copper is removed first as its presence increases the zinc consumption during the desilverizing process. For preliminary copper removal the lead bullion is brought to a temperature of 440°C in a kettle of 60 metric tons capacity. Some tar (or sawdust or resins) is usually added and the kettle is cooled slowly to 400°C while the liquid is stirred. A solid phase, called a dross, floats on top of the liquid and the particles of the solid phase adhere to the tar. This "hot dross" is collected. It contains mostly lead and copper which are partly oxidized and/or sulfurized if the lead bullion contains some sulfur.*

Jan 1, 1963

By J. Kostuik, M. J. de Bastiani

The method of mining the uranium orebody at Denison mine in the Elliot Lake district of Ontario is discussed. Details of the development of haulage-ways and rooms are giuen, as well as methods of ore haulage. The milling and beneficiation stages are noted briefly. Located in the Elliot Lake mining district of Canada, the Denison mine lies between Sudbury to the east and Sault Ste. Marie to the west, Fig. 1. This area is overlain by Huronian sediments filling a basin in the Keewatin basement complex. Subsequent folding of these sediments developed a synclinal structure, known locally as the Quirke Lake Trough, which forms the northern portion of the now famous big Z structure, the geological trademark of this region. Plunging to the west and extending nine miles from the granite outcropping in the north to the Keewatin lava contact to the south, the syncline has dips of 10" to 45" on the north limb and 10" to 20" on the south limb, Fig. 2. The Denison orebody, located on the north limb of the syncline, lies between 800 and 3000 ft below the surface. The main ore zone is within 50 ft of the Missisagi-Keewatin contact (see Fig. 3), and it varies in thickness from 6 to 32 ft. This ore zone has a composite dip of 19" to the south and is composed primarily of two pyritized conglomerate beds separated by a band of pebbly quartzite stratum. The upper conglomerate bed of the main zone varies from 2 to 15 ft in thickness, while the lower conglomerate varies from 2 to 12 ft. Over extended areas, mining is carried out over the entire section comprising the two conglomerate layers and intercalated quartzite; in other areas, the conglomerates are selectively mined, depending on the thickness of the quartz-ite. The ore zone contains approximately 6 pct sulfides and 80 pct silica. The predominant uranium-bear ing minerals are brannerite, uraninite, and an unidentified mineral (probably thucolite). Some of the uneconomic metallic minerals identified to date are pyrite, pyrrhotite, and chalcopyrite. MINE LAYOUT Shafts: Underground exploration and development (Fig. 4) were performed through two shafts 1/2 mile apart. The No. 1 shaft, sunk to a depth of 1856 ft with the main station established at the 1600-ft ore level, is a 250-sq ft, 5-compartment shaft capable of handling 4500 tpd. Two 5x5-1/2-ft compartments serviced by a 12-ft diam double-drum hoist, are used for hoisting 190-cu-ft bottom-dump skips in balance. A 30-man cage, offset by a counterbalance, operates within a 5-1/2x11-1/2-ft compartment. The fifth compartment is used as a manway, pipe, and cable-way. This shaft is also provided with an intermediate pumping station used during the initial mining phase as well as loading-pocket and spill-pocket installations and pumping facilities. The 480-sq ft No. 2 shaft, located down-dip from No. 1 shaft, has a 2776-ft depth. Serving as the main hoisting shaft with a maximum capacity of 9000 tpd, it has eight compartments, four of which are used for hoisting ore in 10-ton capacity bottom-dump skips. These four compartments, measuring 5x6-ft in section, are serviced by two 12-ft diam double-drum semi-automatic hoists. A 50-man cage is operated in a 15x8-ft compartment, and it is counterbalanced by a 12-ton weight. Two compartments are used for ventilation, manway, electric cables, and pipes. A station was constructed at the 1325-ft horizon of the No. 2 shaft for relay pumping. The main sta-

Jan 1, 1961

By E. W. Davis

IF the tonnage of merchantable iron ore remaining in the Lake Superior district is divided by the average of the annual shipments for the past 20 years, it will be found that this ore supply will be exhausted in approximately 35 years. This computed exhaustion period would be an indication of the future activities of the iron-mining industry if it were not for the fact that merchantable ore is being manufactured from low-grade ore, of which there is an almost inexhaustible supply in the Lake Superior district. It is true that at present only the simplest of these low-grade ores are being concentrated to any considerable extent, but progress is being made with the treatment of the more complex ores, and now, in addition to 20 washing plants on the Mesabi Range, three plants are equipped with jigs for the treatment of ore that cannot be concentrated simply by washing. The latest addition to the ore-treating plants of the Mesabi Range is a magnetic roasting and concentration plant at Cooley, Minn., in which ore that cannot be concentrated either by washing or by jigging is roasted to the magnetic state and concentrated on magnetic separators. This plant is beginning its third season of operation, and while it is too soon to make definite predictions, there are strong indica-tions that this new process may make commercially possible the manu-facture of high-grade, merchantable iron ore from large quantities of low-grade ore now considered worthless. After the iron oxide contained in an ore has been converted to mag-netite, almost any desired grade of concentrate can be produced, using magnetic-concentration equipment of the types now in general use for the concentration of the natural magnetites of New York, New Jersey and Pennsylvania. The conversion of hematite (Fe2O3) to magnetite (Fe3O4) is easily accomplished by heating the ore to a dull red tempera-ture in a reducing atmosphere. The reaction is slightly endothermic, and while it requires 200 B.t.u. to heat to 900° F. one pound of hematite ore containing 45 per cent Fe, it requires only 100 B.t.u. to convert the oxide into magnetite. In the laboratory, using small quantities of ore, this conversion is very simple, but large furnaces suitable for commercial

Jan 1, 1936

By J. D. Jones

Unique aspects of tailing pond design aid reclamation facilities for three separate projects are described.

Jan 1, 1978