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By Allen J. Johnson

With a realization of the rapidly increasing importance of automatic stokers as a medium for domestic heating, the Anthracite Institute Laboratory has conducted extensive investigations, over a period of several years, to determine the various outstanding characteristics of stoker design and performance. The purpose of this paper is to summarize these findings as a guide to current practices. Stokees Investigated One or more models of the underfeed stokers listed below were included in the various phases of this investigation: Beckley Gilkoal Burnwell Iron Fireman Combustioneer Motor Stokor Electric Furnace Man Norristown Super-stoker Erie Heat Generator Whitney Fire Ball (Tests Incomplete.) Fuel Saver Principles of Construction.—The operating principle of the leading makes of underfeed stokers is similar (Fig. 1). A plunger1 or slowly revolving worm2, conveys the buckwheat or rice sizes of anthracite to the center of a specially constructed tuyere pot where air is admitted to the coal through suitable ports of varying design. As the fuel burns, it is slowly forced to the outside circumference of the tuyere by the pressure of the incoming coal; eventually the ash falls over the edge of the pot, either entirely by gravity or aided by mechanical sweepers. In at least one model, the entire firepot revolves. While various special details have been included in the design of a number of stokers, they do not affect the general principles as described above, and therefore have not been included in this discussion.

Jan 1, 1936

By Allen J. Johnson

With a realization of the rapidly increasing importance of automatic stokers as a medium for domestic heating, the Anthracite Institute Laboratory has conducted extensive investigations, over a period of several years, to determine the various outstanding characteristics of stoker design and performance. The purpose of this paper is to summarize these findings as a guide to current practices. Stokees Investigated One or more models of the underfeed stokers listed below were included in the various phases of this investigation: Beckley Gilkoal Burnwell Iron Fireman Combustioneer Motor Stokor Electric Furnace Man Norristown Super-stoker Erie Heat Generator Whitney Fire Ball (Tests Incomplete.) Fuel Saver Principles of Construction.—The operating principle of the leading makes of underfeed stokers is similar (Fig. 1). A plunger1 or slowly revolving worm2, conveys the buckwheat or rice sizes of anthracite to the center of a specially constructed tuyere pot where air is admitted to the coal through suitable ports of varying design. As the fuel burns, it is slowly forced to the outside circumference of the tuyere by the pressure of the incoming coal; eventually the ash falls over the edge of the pot, either entirely by gravity or aided by mechanical sweepers. In at least one model, the entire firepot revolves. While various special details have been included in the design of a number of stokers, they do not affect the general principles as described above, and therefore have not been included in this discussion.

Jan 1, 1936

By FRANK COLE

THE territory covered in this discussion includes all the states west of the Mississippi river. Agriculture is expanding each year in this section, but until recent years the application of commercial fertilizers as an aid to crop production was not practised to any great extent. The use of commercial fertilizers has increased somewhat, but is still on a small basis as compared with the tonnages used else- where in the United States. During 1928 these western states used 665,100 tons of all classes of fertilizer as compared 'with 7,933,600 tons used in the whole United States; or this western area, compromising near- ly two-thirds the land area, uses about 5 per cent of the total fertilizer. To show how large a tonnage one state may consume, North Carolina for the year 192s used 1,349,360 tons of commercial fertilizer or about twice the amount used by 22 western states.

Jan 1, 1930

By J. J. Rutledge

FULLY 60 per cent of the serious and fatal accidents in Maryland coal mines are due to falls of roof and side. Usually, the victim of the fall sustains a broken back, sometimes not only the vertebrae being fractured but the spinal cord also being severed. When the spinal cord has not been severed and yet the vertebrae have been broken or injured, it is often possible to rehabilitate the victim of the broken back. - Such accidents are classed as Permanent Total and the victim receives a certain compensation from the State Industrial Accident Commission; sometimes the amount is awarded in a lump sum, but usually it is paid weekly. When the amount allotted to the victim of such an accident has been expended, either in a lump sum or weekly payments, the victim of the accident is dependent on public charity. Some efforts have been made to physically rehabilitate the victims and make them at least partly self-supporting before the expiration of their compensation payments. The State Industrial Accident Com-mission has done some of this rehabilitation. The Maryland Bureau of Mines, in cooperation with R. C. Thompson, Supervisor of Vocational Rehabilitation, State Department of Education, and his assistants, has, through an informal cooperative arrangement, placed several of the victims in hospitals in Baltimore for treatment. Six years ago, through the efforts of the Maryland Bureau of Mines, a dozen or more broken-back victims were examined by an orthopedic surgeon and report was made to the Bureau regarding such cases and the possibility of their rehabilitation. This paper details the result of such examinations.

Jan 1, 1936

ALABAMA. Aldrich.-Aldrich, W. F. Anniston.-Noble, A. E., 20th St. and Wilmer Ave. Auburn.-Brown, R. L., Box 0. Bessemer.-Abbott, C. E., T. C., I. & R.R. Co. Ferguson, V., U. S. C. I. Pipe & Fdy. Co. Williams, E. P., Tenn. C., I. & R. R. Co. Birmingham.-Aldricb, T. H. Aldrich, T. H., Jr., 406 Woodward Bldg. Allen, A. W., 1616 S. 14th Ave. Bowron, J., 1401 S, 20th St. Burbidge, T. A., Browu-Marx Bldg. Coxe, E. H., Tenn. C., I. & R. R. Co. Crawford, G. G., Tenn. C., 1. & R. R. Co. Crockard, F. H., Woodward Bldg. Dimmick, F. D., Dimmick Pipe Co. Ellis, E. E., 1515 Brown-Marx Bldg. Fairbairn, C. T., Woodward Bldg. Fies, M. H., 2316 Highland Ave. Hiller, E., 516 Brown-Marx Bldg. Hillman, M. P. G., 707 Empire Bldg. Ludwig, C. P., 12th Ave. and 12th St. McCormack, G. B., Lookout Mt. Iron Co. McCrery, C., Tenn. C., I. & R. R. Co. Moffett, C. A , 909 Brown-Marx Bldg. Peters, R.. Jr., Brown-Marx Bldg.

Jan 1, 1917

Note by the Secretary.-—In the preceding communication of Mr. Rickard, in the present discussion, as printed in Trans., xxiii., the loss of quicksilver at Pestarena, reported on p. 569, as 230 and 234 grammes per metric ton, is stated as equivalent to about 74 pounds per short ton avoirdupois—an obvious error, which escaped correction in my reading of the proofs, and was not discovered until after Vol. XXIII. had left the press. The true equivalent is 0.46 pound or about 7 1/2 ounces (instead of pounds) per short ton.— R. w. R. Philip Argall, Denver, Colo. (communication to the Secretary) : Mr. Rickard's last contribution to this discussion* calls for some reply from me, if only by way of defending myself against the charge (p. 569) that my criticisms of his paper were "unnecessarily hypercritical and occasionally unfair." At the same time I am fully aware that our Transactions are not the place for mere personal controversy, and that the sole object of discussion is to define differences of opinion, and defend opposing views as a means of eliciting the truth. Mr. Rickard disclaims the statement, which he says I attributed to him, that in the slow-crushing Gilpin county mills the pyrites remain longer in the mortar than the other portions of the ore. My understanding of his statement was based on the following passages in his paper: " Particles of ore, which have heen pulverized to a fineness which would permit of their exit through the screen, are enabled to settle towards the bottom of the mortar. It would he expected that the heavy metallic minerals occurring in the ore would, because of their greater specific gravity, be most affected by this feature of the treatment. In practice this is found to be so. The fine slimes contain a large proportion of metallic sulphides, generally valuable on account of their close association with the precious metals, while the coarsest particles to be found in the tailings usually consist of quartz and other minerals forming the less heavy gangue (Trans., xxiii., 139).

Jan 1, 1895

By J. Randel Hill

The 64th Texas Legislature passed the "Texas Surface Mining and Reclamation Act," Chapter 131, Texas Natural Resources Code (subsequently referred to as "the Act"), at a point in time when little surface mining had taken place within the state. Thus, enactment of regulatory control governing mining operations in our state has, for the most part, preceded widespread, intensive mining activity. I should point out that the statute applies only to the extraction of coal, lignite, uranium and uranium ore. A recent opinion rendered by the Attorney General's office has stated that extraction of the named elements, when it occurs incidental to the extraction of other materials, e.g., clay, is not not an activity subject to the Act. An important theme of the Act, frequently overlooked in other environmentally oriented legislation, is recognition of the Act's affect on the mining industry. The Act states that "the extraction of minerals by surface mining operations is a basic and essential activity making an important contribution to the economic well-being of the state and nation" and, in reference to reclamation being accomplished contemporaneously with mining, provides a recognition that "the extraction of minerals by responsible mining operations is an essential and beneficial economic activity." This legislative recognition is, of course balanced against the need for proper mined land reclamation, the rights of surface owners, the need to guard against unreasonable degradation to land and water resources and numerous other actions or events that the Legislature wanted protected. Another rather pervasive general theme that is established in the Act is the concept that the agency is entitled to obtain whatever information, or take whatever action, that appears reasonably necessary to effectuate the purposes of the Act. This concept, coupled with the detailed requirements placed on mining operations in the portions of the Act dealing with Permit Applications, Reclamation Plan and Reclamation Standards, easily insures that surface mining activities can and will be regulated to the extent necessary. Section 131.102(b)(2) is probably the most relevant provision in the Act which deals with the preclusion of mined lands becoming waste lands. This portion of the Act states that the surface mining operator shall: ". . . restore the land affected to the same or a substantially beneficial condition. ." In this language the Legislature had made it abundantly clear that the abandoned or orphaned lands found in some of the Eastern states, will not be tolerated in this State, and provided the Commission with a degree of latitude to determine what condition would be appropriate in each individual mining situation. I bring this area of the Act to your attention because it is the area which has received the most inquiries and concern by operators, i.e. what does "substantially beneficial" constitute? The Commission's staff has spent a considerable amount of time wrestling with the statutory language "substantially beneficial" to determine the legislative intent and provide operators with guidance of what they can expect. In this regard, the most definitive criteria in our opinion lies in the Act's legislative hsitory. The Legislature had before it basically three reclamation standards namely: House Bill 656, considered to provide the most stringent reclamation standard and identical to Senate Bill 66; House Bill 1717 which was supported by industry spokesmen and was considered to contain the least stringent reclamation standard; and Senate Bill 55 which was adopted by the Legislature. During the Bill's initial hearing before the House Environmental Affairs Committee, the House sponsor of the Senate Bill 55, which was the Bill eventually adopted, made the following statement: (I am quoting verbatim from the Committee's transcript although substituting the speaker's reference to the authors names with the Bill's numbers.) "An example of the differing approaches of the four bills can be seen in the area of reclamation standards and this is critical. House Bill 656, talking about restoring the surface of the land, House Bill 656 has this statement: 'At least fully capable of supporting the use to which it was capable of supporting prior to any mining or any higher or better use.' In other words you have to restore it to the level it was prior to the mining. Senate Bill 55: 'Restore the land to the same or substantially beneficial use.' Substantially beneficial use. (Emphasis his) House Bill 1717 says: 'Restore insofar as practical to appropriate beneficial post-mining use.' So that House Bill 1717 said to, 'restore insofar as practical to appropriate beneficial use. I think that's too weak, whereas I think the House Bill 656 that would call you to restore it to at least the use it had prior to the mining may also be too tight the other way. I think the Senate Bill 55 approach is down the middle of the road which says that you do restore it to the 'same or substantially beneficial use,' is a proper way to go there." Therefore, the conclusion that we have drawn from the legislative history of the bill is that the extent of reclamation required by "substantially beneficial" may be something other than the use it was prior to

Jan 1, 1979

By A. Weiss, W. A. Coster

The search for ore is characterized by a great variety of uncertainties, each of which can be resolved by obtaining information at a cost. Three exploration stages may be distinguished in which information can be obtained, based on inherently different cost structure: 1) the reconnaissance or scanning stage, 2) the examination or screening stage and 3) the project stage. This exploration sequence would roughly coincide with replies to questions as to: where, how, why and how much. As complete information in each stage is too costly to acquire, we must assess the probability that adequate information will be furnished by a limited amount of effort and attempt to maximize the expected value of ore to be found for a given exploration expenditure. Several problems are discussed relative to the mathematical formulation and possible computer procedures for determining the optimum allocation of a total exploration effort. Based on the available literature possible solutions to this problem are indicated. When scanning through published literature on mineral exploration, it seems at first that there is little room for substantial and systematic improvements in the efficiency with which the problem of discovery of new ore deposits is presently being handled by large organizations active in exploration. It appears equally difficult to offer something relevantly new which could generate a break-through in exploration thinking and cause a marked improvement in the ratio of successful undertakings to the total exploration projects started. On the other hand, a number of experts in recent years have urged that the problems in prospecting be analyzed in a more skillful and sophisticated manner than in the past. Their thesis is based mainly on the premise that the cost of finding mineral deposits will increase with increasing technical difficulties. In present large-scale exploration ventures, especially in those regions where outcrops and immediately visible geologic evidence are scarce, older methods of prospecting are increasingly being replaced by more indirect and systematic geophysical and geochemical methods with more emphasis on correct statistical design of exploration patterns. It is perhaps the oil industry which has made the greatest strides in developing statistically, well justified patterns in its search for oil; possibly because oil seepages, as indicators of the presence of oil, left off at an earlier point in time than did outcrops as indicators of base metals. Among the pioneers in the field of statistics and operations research, as applied to mineral exploration, the excellent works of Allais, Slichter, Koop-man, Mickey, de Guhnin, Krumbein, Griffith, Sichel, Krige, de Wijs, and Matheron may be mentioned. It should, however, be pointed out that three subjects of basic importance to the allocation of exploration efforts have so far received only scant attention in published literature, even by the aforementioned authors. In the first place, a more precise definition of the object of the search, i.e., a minimum-size orebody, seems to be outstanding. Secondly, a decision model is not a widely-discussed subject. Thirdly, no concentrated attempt so far seems to have been made to establish probabilities of the occurrence of economic deposits on a regional scale and to arrive at a slightly more accurate knowledge of the probability laws governing the deposition of ore. It is not the purpose of this paper to create new order in the complexity of uncertainties in which our decision processes in exploration necessarily have to be conducted. Rather, we intend to highlight some of the outstanding, hitherto unmapped territory, where diligent compilation and a utilization of present and historic data may statistically improve our chances of success. We hope that the contribution of this paper will lie in bringing allocation problems into better focus and in increasing the mineral industry's realization of the magnitude of the factors involved. THE MINIMUM-SIZE OREBODY The concept of target specifications for what constitute a minimum-size orebody in exploration is a rather variable one and depends to some extent on

Jan 1, 1963

By Donald F. Hammer, Donald W. Peterson

The Magma mine at Superior, Arizona, has produced over 13 million tons of ore yielding 1.5 billion pounds of copper. It is a mesathermal deposit, and, although the bulk of the ore has come from the Magma vein, most of the recent production has come from replacement deposits in limestone. The mine lies in a Precambrian and Paleozoic sequence of rocks that includes schist, diabase, quartzite, shale, and limestone; nearby, these rocks are intruded by igneous bodies of Mesozoic age that were probably the source of the ore-bearing fluids. Locally, these rocks are overlain by Cenozoic volcanic rocks and conglomerate. Layered rocks at the mine dip eastward about 30°. The area is extensively faulted, and surface faults are grouped into an earlier east-trending set and a later northtrending set. An additional set of diagonal faults that trends northwest and northeast is recognized underground. The east-trending Magma vein-fault, with its splits and branches, is the principal mineralized structure of the district. The bulk of the ore occurs in large ore shoots that plunge steeply westward and are sporadically connected by irregular ore shoots dipping gently eastward. The main ore controls apparently are selective zones of permeability related to the transverse faults. A bed of crystalline limestone near the base of the Martin Limestone (Devonian) is the host for the replacement ore bodies-discontinuous tabular pods dipping eastward parallel to the bedding. Selective permeability is again the apparent ore control, caused both by local hydrothermal solution of limestone and by deformation along faults. The principal copper minerals in the vein are chalcopyrite, bornite, enargite, tennantite, chalcocite, and digenite; these minerals vary in abundance according to a distinct zoning pattern. The upper part of the mine yielded considerable zinc as sphalerite, and the oxidized zone was rich in silver. The chief gangue minerals are pyrite, quartz, and hematite. In the limestone replacement bodies, chalcopyrite and bornite are the chief ore minerals.

Jan 1, 1968

By Edwin B. Wilson, Joseph W. Leonard, Richard W. Borio

preparation of specification coals for the utility industry is approached from the standpoint of a cooperative effort with the power company to assure that the shipped product will be a noncorrosive coal. Selective mining, coal preparation, the use of additives, and coal blending are mine-site techniques proposed as means for upgrading corrosion-retarding constituents of utility coals (CaO and MgO) while, at the same time, reducing the concentration of those constituents of coal (Na20 and K,O) which cause corrosion. Data obtained from large-scale boiler testing in combination with bench-scale physical and chemical tests are used as a basis for the formulation of mine-site procedures to improve coal combustion utilization. Electric power generation remains the greatest market for coal in the United States. A major reason for this strong market has been the ability of the coal industry to supply a superior product for combustion while maintaining competitive prices. Now that the coal industry is engaged in intensive competition with nuclear power for future energy demand, it becomes ever more imperative that superior coal products are produced. One important problem when burning some coals is a liquid phase corrosive attack on boiler tube metal in the superheater and reheater areas of the furnace where steam temperatures may exceed 1050°F. In addition to causing power outages and high maintenance costs, corrosion is a continuing barrier to the future development of more efficient steam cycles which permit lower generation costs when using coal. Research methods of the past which have been directed at finding solutions which could be applied at the power plant site have been only partially successful and are generally costly. This paper contains a suggested --method of corrosion control through investigation of the problem at the source of the trouble—the coal supplier facility. It is proposed that mine-site pre-ventative procedures be considered as an effective means of cooperative corrosion control between the power company and the coal supplier. Economic justification must be applied to the individual situation. This paper is based on recent work by Combustion Engineering, Inc. and the Coal Research Bureau of West Virginia University under a contract from the Department of the Interior Office of Coal Research.',' Results which are of importance to this discussion may be summarized as follows: 1) The alkali minerals of coal (Na2O and K2O), as measured by an acid leaching process, can be related to corrosion rate in utility boilers. As these constituents increase in a coal product, its corrosiveness can be expected to worsen. 2) The alkaline-earth minerals contained in coal, reported as total CaO and MgO reduce corrosiveness 2s their concentration increases. 3) Naturally occuring, alkaline-earth-bearing materials, such as limestone and dolomite, may be added to a coal to reduce its corrosiveness. 4) Coals with very low iron contents tend to be less corrosive. These results provide the groundwork for examination of the system of operations which occur at the supplier facility from the seam face where mining is begun to the point of loading for shipment. The Mining System Fig. 1 is a cross section of one of the typical coal seams (designated coal A) that was boiler tested during this research program. This seam is overlain by material which consists primarily of a gray-black shale. In the lower third of this seam, there exists a thin rock parting of less than 4 in. in thickness which is consistent throughout the seam. The floor material is fireclay. In order to examine mineral distribution throughout this particular seam, the Coal Research Bureau collected a

Jan 1, 1971

By H. NORTON JOHNSON

THE oil industry in California during 1929 reached new heights and new depths in the discovery and development of the oil resources of the State. The discovery of new fields, and more especially the discovery and development of deeper prolific sands in known fields has, for the first time in its history, brought the potential production of completed wells within the State to over 1,000,000 bbl. oil per day. Constant improvement in equipment and technique has made possible economic development to depths unheard of but a few short years ago. Commercial production from a depth of over 4000 ft. was considered quite an accomplishment in 1923 when the Meyer sand at Santa Fe Springs was developed, and when later oil was successfully raised from this depth.

Jan 1, 1930

By Maynard H. Jameson

Earlier investigations of the potential-drop-ratio method of electrical prospecting have indicated that under suitable conditions this method is well adapted to the location of formation boundaries in stratified ground. A description of this development was given several years ago by H. Lundberg and Th. Zuschlag.l The curves published by these authors for the potential-drop-ratio variation above a horizontal contact indicated a definite relation of the position of the curve peak to the depth of the interface. The theory underlying this relation was subsequently studied by Z. Mitera in greater detail,' and the theoretical deductions were compared with the results of tank experiments. The investigations available at this writing were confined to studies of horizontal formation boundaries. It is the purpose of this paper to extend the scope of the previous work to the problem of dipping layers. Theory Consider the case of three media of different resistivities, whose interfaces are not parallel. If a point-source is located in one of these interfaces, its images do not lie in a straight line, but on the circumference of a circle whose center is at the hypothetical junction of the interfaces. R. F. Aldredgea determined the relation that exists between the degrees of dip of the two interfaces and the distances between the various images and the point for which the potential is to be found. As seen in Fig. I, three media of resistivities PO, p1, and p2 are involved, and the source I is located at the interface of the media Coo) and (p1). The perpendicular depth of the lower interface is h, 0 is the dip, R is the distance between source I and potential point P, and r is the distance between the images and that point. To distinguish between images lying above the ground interface and those below, the notation "odd" and "even" images will be employed; images below the ground interface will be termed "odd" and those above "even." The following relations govern the distances between either kind of images and the potential point: EvEn Odd Ta — R r1 - [rl] - [RS + 4h(h + R sin 01½ r, = [r] =. [R1 + 4h cos 0)2(h + -R sin 0)1½ ri - [r3] ={r3} [R* + 4h(4 cos2 0 - i)1 (h + R sin 0)l½ r4 = [r4] = [R2 + 4h(4 cos $ cos 30)1 (h + R sin 0)]½ r, — [r4] - [R2 + 4h(4 cos9 R cos 20 + cos 48)2 (h + R sin 01½ I RI + 4h[2 cos 30(4 cos2 0 - I)12 (h + R sin 8)1 ½ rn - [r4] - [R2 + 4hlf(cOs 0)18(h + R sin R)l½ As previously pointed out, the images of the source are on the circumference of a circle. If the angle of dip is 0, the angle measured from the horizontal to the first image is 28; to the second image it is 48, and so on. Since the limit of the reflecting interface is at its outcrop, the last possible

Jan 1, 1946

By Maynard H. Jameson

Earlier investigations of the potential-drop-ratio method of electrical prospecting have indicated that under suitable conditions this method is well adapted to the location of formation boundaries in stratified ground. A description of this development was given several years ago by H. Lundberg and Th. Zuschlag.l The curves published by these authors for the potential-drop-ratio variation above a horizontal contact indicated a definite relation of the position of the curve peak to the depth of the interface. The theory underlying this relation was subsequently studied by Z. Mitera in greater detail,' and the theoretical deductions were compared with the results of tank experiments. The investigations available at this writing were confined to studies of horizontal formation boundaries. It is the purpose of this paper to extend the scope of the previous work to the problem of dipping layers. Theory Consider the case of three media of different resistivities, whose interfaces are not parallel. If a point-source is located in one of these interfaces, its images do not lie in a straight line, but on the circumference of a circle whose center is at the hypothetical junction of the interfaces. R. F. Aldredgea determined the relation that exists between the degrees of dip of the two interfaces and the distances between the various images and the point for which the potential is to be found. As seen in Fig. I, three media of resistivities PO, p1, and p2 are involved, and the source I is located at the interface of the media Coo) and (p1). The perpendicular depth of the lower interface is h, 0 is the dip, R is the distance between source I and potential point P, and r is the distance between the images and that point. To distinguish between images lying above the ground interface and those below, the notation "odd" and "even" images will be employed; images below the ground interface will be termed "odd" and those above "even." The following relations govern the distances between either kind of images and the potential point: EvEn Odd Ta — R r1 - [rl] - [RS + 4h(h + R sin 01½ r, = [r] =. [R1 + 4h cos 0)2(h + -R sin 0)1½ ri - [r3] ={r3} [R* + 4h(4 cos2 0 - i)1 (h + R sin 0)l½ r4 = [r4] = [R2 + 4h(4 cos $ cos 30)1 (h + R sin 0)]½ r, — [r4] - [R2 + 4h(4 cos9 R cos 20 + cos 48)2 (h + R sin 01½ I RI + 4h[2 cos 30(4 cos2 0 - I)12 (h + R sin 8)1 ½ rn - [r4] - [R2 + 4hlf(cOs 0)18(h + R sin R)l½ As previously pointed out, the images of the source are on the circumference of a circle. If the angle of dip is 0, the angle measured from the horizontal to the first image is 28; to the second image it is 48, and so on. Since the limit of the reflecting interface is at its outcrop, the last possible

Jan 1, 1946

By Hiram B. Woon

Uranium ore deposits in the Lisbon Valley area are in an arcuate belt, 15 miles long by one-half-mile wide, on the southwest flank of the Lisbon Valley anticline. They range in size from 500 to 1,500,000 tons and by mid-1965 had yielded 6,147,000 tons containing 48,530,000 pounds of U3O8. Ore bodies average 6 feet thick, are tabular, amoeba-shaped masses, concordant to the bedding, and are in the thickest, lowest sandstone unit of the Moss Back Member of the Chinle Formation of Triassic age. The host rock is predominantly a fluviatile, calcareous, fine-grained to conglomeratic sandstone. Uraninite, the principal ore mineral, fills the pores in the sandstone and partly replaces sand grains and fossil wood fragments. During Late Permian and Early Triassic time pre-Chinle Formations were arched to form the ancestral Permian anticline. Moss Back streams truncated Moenkopi and Cutler beds which capped the ancestral anticline and then covered it with fluviatile elastics, which were subsequently covered by thousands of feet of Triassic, Jurassic, and Cretaceous sediments. Uranium, probably derived from the Chinle Formation by diagenetic processes, was transported in connate ground waters, was moved by compaction or hydrostatic forces, and was deposited under reducing conditions. Uranium was emplaced around the crest of the ancestral anticline, prior to the Laramide orogeny. During the orogeny, the Tertiary-Lisbon valley anticline was super induced on the Permian anticline and, penecontemporaneous with uplift, was faulted parallel to its longitudinal axis. The Big Indian ore belt on the southwest flank footwall block was elevated to approximately its present position, and the northeast flank hanging wall block was elevated only slightly. An extension of the Big Indian ore belt around the northeast flank of the ancestral Permian anticline may exist in the Moss Back sandstone in the downthrown block northeast of the Lisbon Valley fault.

Jan 1, 1968

By J. M. Woodall

GuAs crystals which have been grown in quartz boats by the horizontal Bridgman method in the pvesence of Ga20 vapov have beetz found to have carrier and donor distributions which do not correspound to those expected from simple dopant seg-vegation during directional freezing; Instead, the carrier distribution is determined by the heat-trentnzent history of the crystal, while the donor distribution, zohiclz is principally due to silicon, is fixed by the pozuth rate, the geo)tlet.ry of the crystal growth vessel, and tlze initial Ga20 pressure. WHEN semiconducting materials are made into doped crystals by the normal freezing method,&apos; they usually exhibit doping variations along the growth axis. If a) there is no dopant diffusion in the solid, b) the dopant is distributed uniformly in the melt, and c) the distribution coefficient, k, does not vary with composition, then the doping variation along the growth axis is represented by the equation: where C is the doping level in the solid at a point where a fraction g of the original liquid has frozen, and Co is the mean concentration. When the dopant is either a singly ionized shallow donor or shallow acceptor, C also represents the carrier concentration. Even though this equation accurately describes the dcping profiles of a large number of normal freeze systems, there are several special systems for which Eq. [I] does not apply. One such system is the horizontal Bridgman method for preparing oxygen-grown GaAs crystals using quartz vessels. Several workers2"* have shown that GaAs crystals grown by the horizontal Bridglnan method using quartz vessels are generally contaminated with silicon in concentrations in excess of 5 < 10lG atoms per cu cm. This contamination is ascribed to a reaction: occurring at the walls of the crystal-growth vessel which liberates silicon into the melt and Ga2O vapor. It has been shown4 that this reaction, and, hence, the silicon contamination, can be suppressed by the addition of oxygen to the crystal-growth apparatus. It is the purpose of this paper to describe a special apparatus capable of yielding single crystals of GaAs grown in the presence of oxygen and to describe both the kinetics of silicon suppression in this system and the relationship between the carrier concentration profile and the silicon concentration profile. EXPERIMENTAL-CRYSTAL GROWTH A schematic diagram of the apparatus used in the oxygen addition experiments is shown in Fig. 1. The most important features of this apparatus are: a) the use of a sand blasted quartz boat, h) a quartz rod of length 1, with a hole of cross section A, that is placed near the boat to limit the free space volume V, over the melt during the growth, and c) the temperature gradient at and near the solid-liquid interface. Sand blasting the boat is necessary to prevent wetting of the melt. The quartz rod retards the diffusion of the GazO vapor away from the melt to the colder portions of the ampoule. A crystal is prepared by first loading a 5.5-in. boat, which has been cleaned in aqua regia, with 40 g of 99.9999 pct Ga along with 1 to 8 mg of Ga203 powder. GazO3 is a convenient source of oxygen since it reacts with gallium at the melt temperature to form Ga20 vapor, the species which apparently controls the suppression of silicon contamination. The loaded boat, the quartz rod, and the 99.9999 pct As are placed in the ampoule as shown in Fig. 1. Generally, GaAs seeds were not used since most of the unseeded growths resulted in monocrys-tals. The ampoule is evacuated to 10-5 Torr and sealed off. The GaAs melt is synthesized by placing the ampoule into a two-zone horizontal Bridgman furnace. The two zones are separated by several sandwiched layers of -in. Fibre-Fax board drilled with holes slightly larger than the OD of the ampoule. This causes a very large temperature gradient between the two zones, which is necessary for single-crystal growth. The two-zone furnace is mounted on a stand fitted with a roller bearing which allows uniform motion of the furnace in a horizontal direction. A uniform velocity of the stand is achieved by the use of a windlass device which winds up a wire attached to the stand. Movement of the solid-liquid interface is accomplished by fixing the position of the ampoule and moving the stand. Growth rates investigated in this experiment were between 0.4 and 1.2 in. per hr. The composition of the melt is fixed by maintaining an arsenic reservoir at 618°C. The stand is moved away

Jan 1, 1968

By F. R. Koeberlin

ABOUT thirty miles south of the port of Coquimbo, Chile, nestling in one of the western outliers of the main Andes range, lies the little mining town of Andacollo, a place whose history and traditions make up one of the most romantic pages in the life story of this southern republic. The beginning of Andacollo is shrouded in the penumbra of the pre-Columbian era, but its first mining activity probably dates from about the years 1440 to 1460. It was in the middle of the fifteenth century that the Inca Tupac-Yupanqui, grandfather of Atahualpa, conquered this part of Chile. His domain extended even as far south as the present site of Santiago, and perhaps farther, but was maintained with increasing difficulty against the fiercely independent and indomitable tribes of Araucanian Indians of the South.

Jan 1, 1938

J. H. HEGINBOTHAM, a, metallurgist of the General Engineering Co., talked on "Current Milling Practice at Kirkland Lake," at the December meeting of the Utah Section. The ore is enough alike through the whole district so that some generalizations and comparisons may be made. The question as to whether or not the flotation process should be used in the flowsheet for extracting gold by cyanide solutions is still being vigorously debated, and it will seemingly need some years for a definite answer to be given. Most of the gold is either free, though much of it is finely dispersed in quartz, or occurs with pyrite. At times there may be 2 per cent of telluride compounds in the ore, but the amount of gold telluride present is small and has not been definitely established. It has been shown by Dr. Haultain and others that though gold tellurides may be so finely disseminated that it is necessary to grind the ore exceedingly fine, the compounds themselves are not difficultly soluble. (An increase in temperature helps to dissolve tellurides, and also to settle pulps.) It is likely that if the ore were ground through 400 mesh, practically all of the gold would be soluble. As it is, with 96 to 98 per cent of the ore ground to minus 200 mesh, and some 70 per cent minus 325, the cost of

Jan 1, 1934

By Morgan Walker

INTERMITTENT injection of gas in gas-lift pumping is a variation of the common practice in that the gas is&apos; .delivered to the well for a short, period, called the "on time," followed by a period during which none is admitted, called the "off time," instead of being admitted continuously at a constant rate or by intermittent flowing in which it is occasionally delivered to the well in just sufficient quantity to flow off the accumulated head of fluid. The term "gas" is used throughout this discussion but it should be remembered that in so far as the operation is concerned either air or natural gas may be used. The equipment at the well is the same as commonly used in gas-lift installations and gas may be admitted to either the tubing or the casing. It seldom occurs that all the wells on a lease can be pumped economically by intermittent injection from one header. Wells that. have flow characteristics which permit their being handled together have their intake lines grouped at a central compressor station. Well groups may consist of two or more wells. The total volume of gas delivered by each group of compressors goes to one well at a time through a quick opening valve, each well connected to the header receiving its charge of gas in turn. Special cases may require a deviation from this arrangement. The distribution of the gas to the different wells is effected by an automatic timing device which operates quick-opening valves on the intake lines. The timing mechanism may be actuated by electricity, liquid or gas pressure. The essential factor in the operation of the timing mechanism is that as one intake valve is closed another must be opened.

Jan 1, 1928

By Morris Cohen

STAFF: Editor, Gerhard Derge Acting Editor, Paul G. Shewmon Carnegie Institute of Technology Schenley Park Pittsburgh 13, Pa. Editorial Assistant, M. A. Redmerski Production Editor, Otto T. Johnson THE METALLURGICAL SOCIETY: Karl L. Fetters, President; J.S. Smart, Jr., Past-President; R. C. Cole, Vice President; R. L. Hennebach, Treasurer; R. W. Shearman, Secretary. PUBLICATIONS COMMITTEE OF THE METALLURGICAL SOCIETY: W. O. Phil-brook, Chairman; H. L. Bishop, R. C. Cole, J. N. Hobstetter, W. A. Krivsky, E. R. Morgan, F. C. Langenberg, R. E. Lund, Paul Queneau, L. L. Seigle, R. L. Smith, and T. V. Wainwright. Review and selection of manuscripts is under the supervision of the following Publicotions Committes: Extractive Metallurgy Division: R. E. Lund, Chairman; M. E. Wadsworth, Vice Chairman; D. H. Baker, Jr., G. M. Bell, R. E. Grace, W. A. Krivsky, R. A. Lewis, Charles O&apos;Neill, A. W. Schlechten, R. E. Shinkoskey, and W. W. Stephens. Iran and Steel Division: T. V. Wainright, Choirman; H. L. Bishop, R. E. Boni, T. E. Dancy, D. W. Murphy, Johannes M. Uys, J. B. Wogstoff, and R. G. Ward. Institute of Metals Division: J. N. Hobstetter, Chairman; P. A. Beck, J. J. Becker, G. F. Bolling, J. 0. Brittain, J. B. Clark, R. S. Davis, A. E. Dwight, R. W. Fountain, L. R. Girifolco, J. C. Gurland, H. S. Kalish, E. L. Harmon, J. J. Heger, A. A. Hendrickson, L. Himmel, J. P. Hirth, H. H. Johnson, Jr., R. R. Nosh, T. N. Rhodin, R. H. Richman, H. C. Rogers, W. Rostoker, C. Sherby, C. W. Spencer, L. Slifkin, J. K. Stanley, R. Steinitz, H. C. Stumpf, and R. Swalin. Published bimonthly by the Americon Institute of Mining, Metallurgicol, and Petroleum Engineers, Inc., 345 East 47th Street, New York 17, N. Y. Telephone PLaza 2-6800. Subscription $30 peryear for non-AIME members in United States and North, South, and Centrol America; $32, foreign; $30per$7.50 for AlME members. Single copies, $6.00, single copies foreign, $6.50. The AlME is not responsible for any stotement made or opinion expressed in its publications ... Copyright 1962 by the American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. . . . Registered cable address, AlME New York . . . Indexed in Engineering Index, Industrial Arts Index, and Chemical Abstracts . . . Second class postage paid at New York, N. Y., and Ann Arbor, Mich. Volume 224, Number 4.

Jan 1, 1962

By G. V. Kurdjumou

STAFF: Editor, Gerhard Derge Acting Editor, Paul G. Shewmon Carnegie Institute of Technology Schenley Park Pittsburgh 13, Pa. Editorial Assistant, M. A. Redmerski Production Editor, Otto T. Johnson THE METALLURGICAL SOCIETY: Karl L. Fetters, President; J. S. Smart, Jr., Past-President; R. C. Cole, Vice President; R. L. Hennebach, Treasurer; R. W. Shearman, Secretary. PUBLICATIONS COMMITTEE OF THE METALLURGICAL SOCIETY: W. 0. Phil-brook, Chairman; H. L. Bishop, R. C. Cole, J. N. Hobstetter, W. A. Krivsky, E. R. Morgan, F. C. Langenberg, R. E. Lund, Paul Queneau, L. L. Seigle, R. L. Smith, and T. V. Wainwright. Review and selection of manuscripts is under the supervision of the following Publications Committes: Extractive Metallurgy Division: R. E. Lund, Choirmon; M. E. Wodsworth, Vice Choirmon; D. H. Boker, Jr., G. M. Bell, R. E. Grace, W. A. Krivsky, R. A. Lewis, Chorles O&apos;Neill, A. W. Schlechten, R. E. Shinko~ke~, and W. W. Stephens. Iron and Steel Division: T, V. Wainright, Choir- mon; ti. L. Bishop, R. E. Boni, T. E. Doncy, D. W. Murphy, Johonnes M. Uys, J. B. Wogstaff, ond R. G. Word. Institute of Metals Division: J. N. Hobstetter, Choirmon; P. A. Beck, J. J. Beckar, G. F. Boiling, J. O. Brittain, J. 0. Clark, R. 5. Davis, A. E. Dwight, R. W. Fountain, L. R. Girifolco, J. C. Gurlond, H. S. Kolish, E. L. Harmon, J. J. Heger, A. A. Hendrickson, L. Himmel, J. P. Hirth, H. H. Johnson, Jr., R. R. Nosh, T. N. Rhodin, R. H. Richrnon, H. C. Rogers, W. Rostoker, O. Sherby, C. W. Spencer, L. Slifkin, J. K. Stanley, R. Steinitz, H. C. Stumpf, ond R. Swolin. PuUlished bimonthly by the American lnstitute of Mining, Metallurgical, and Petroleum Engineers, Inc., 345 East 47th Street, New York 17, N. Y. Telephone PLaZa 2-6800. Subscription $30 peryear for non-AIME members in United States and North, South, and Central America; $32, foreign; $30peryear$7.50 for AIME members. Single copies, $6.00, single copies foreign, $6.50. The CentralAmerica;AlME is not responsible for any statement made or opinion expressed in its publications ... Copyright 1962 by the American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. . . . .Copyright.Registered cable address, AIME New York . . . Indexed in Engineering Index, Industrial Arts Index, and Chemical cableaddres .. . AlME class postage paid at New York, N. Y., and Ann Arbor, Mich. Volume 224, Number 3.

Jan 1, 1962