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By Charles P. Berkey, John B. Hastings

The reconnaissance of the Goldfield mining-district, describecl in this paper, was made in May and June, 1905, and, though this time was too short for a complete report, the work accomplished may serve as a basis for more thorough future research. Dr. Berkey has examined the rocks collected by me, and I am using his classifications. As a result of further field-work, and Dr. Berkey's examination of the rocks, this paper is an elaboration and correction of my views expressed in the Gold-$elm Sun, May 12, 1905. The sketch-map, Fig. 1, illustrates the geology of the Goldfield mining-district. Goldfield is an eruptive complex, consisting of alaskite (hinary granite), hornblende-andesite, hornblende-dacite, rhyolite, pyroxene-andesite, pyroxene-dacite (sometimes containing a small quantity of olivine), quartz-felsite, olivine-pyroxene-ande-site, and basalt. Considering this list to be arranged in the order of eruption, the age-sequence of the rocks conforms to Richthofen's law, formulated in 1868. From his observations in Europe and America, propylite, andesite, trachyte, rhyolite and basalt, occurring together, succeed one another. In a general way, the medium and the more acidic rocks precede the most basic—a result supposed by some to hare arisen from their position beneath the. surface, and due to a rude stratification by gravity in the original cooling magma during the older history of the earth, or to the same differentiation occurring during a quiescent (molten ?) period preceding eruption, being aided by the ease with which acidic rocks, mixed with water vapors, become fusible. In effect, the more basic and less re-

Jan 1, 1907

In 1936 the Institute established the Anthony F. Lucas Gold Medal, which will be awarded from time to time "for distinguished achievement in improving' the technique and practice of finding and producing petroleum." These awards will be sponsored by the Petroleum Division. Captain Lucas was a pioneer in the oil industry, one of the early wildcatters and a leading mining and petroleum engineer. He was famous as the discoverer of Spindletop. He became a member of the Institute in 1895 and in 1913 was the first Chairman of the Petroleum and Gas Committee of the Institute, the forerunner of the present Petroleum Division. He also headed the Committee in 1914, 1917 and 1918. Medals Awarded To J. Edgar Pew, February, 1937 Henry L. Doherty, February, 1938 Committee on Award H. H. Power, Chairman Until Feb., 1939 Until Feb., 1940 R. Ogarrio W. B. Heroy H. H. Power C. V. Millikan Carl A. Young J. Edgar Pew Until Feb., 1941 Until Feb., 1942 Joseph Jensen M. Albertson John M. Lovejoy H. L. Doherty Carroll H. Wegemann E. G. Gaylord Members ex-officio D. C. Barton John W. Finch Axtell J. Byles D. C. Jackling

Jan 1, 1938

By Roswell H. Johnson

The principle of sliding or graduation in royalties is accomplished either by the block, period, cumulative, or class method. The block method calls for a very low royalty rate on all oil produced up to a certain amount. This amount would normally be that which is believed to suffice to repay the cost of the well. A higher rate would be charged after the well is making a profit. This method, common in many industries, is peculiarly inadaptable to any industry such as this where the productivity per day of the units gradually and inevitably decreases. This, for reasons given later, is because it forces an early abandonment of the well and so offends against conservation. In the period method, the royalty rate is changed by some definite amount when the well produces less than a specified quantity per day or other given unit of time. While simple to explain, it operates badly because a great deal is made to depend upon a small reduction in production, whereas the reduction as a matter of fact declines rather erratically owing to the exigency of lease management, connecting of tankage, and vagaries of the gaugers. These disadvantages are obviated by the cumulative method. In this method, all the production less than a certain amount per week has one rate of royalty, or none at all, and the oil produced in excess of that amount pays an additional rate of royalty. In the long run the calculation is probably no greater than with the period method, for simple tables will be published and printed in the oil papers that can be cut out, enabling quick readings to be made. Even without the table the calculation is easy with the few royalty rates, two or three, which would be used. In this method, the amount paid in royalty declines gradually, rather than suddenly as in the period method. The following reasons might be advanced for the adoption oi cumulative royalties: 1. To distribute the burden in accordance with the capacity to pay. This principle is a unique one in business, although familiar in taxation. This is because it does not distribute reward in proportion to efficiency.

Jan 1, 1916

By T. F. Mitchell

During the investigation or the occurrence of manganese deposits in western United States, Bureau of Mines' examining engineers collected samples from four manganese properties in the Death Valley region, California. These were supplemented by samples submitted by owners of two other properties in the same area. Extensive laboratory tests were made to determine the, amenability of the ores to standard ore-dressing concentration methods. A small sample of high-grade oxide manganese ore from the McWhinney property, San Bernardino County, Calif., was submitted by the owner. Although the sample would sinter directly to plus 48 percent manganese grade, it appeared probable that the ore, if mined in quantity, would be lower in grade and would require beneficiation. Therefore, testing was conducted to remove the chief gangue constituent, calcite. The National Resources, Inc., property (also known as the old Owl Hole mine) is in the Owl Hole Springs district, I mile from Owl Hole Springs, San Bernardino County, Calif., near the southwest corner of Death Valley National Monument. The ore deposits occur as small lenses or ,pockets, evidently .replacements in limestone and granite. Laboratory work was done on a representative sample of orb procured by Bureau engineers.

Jan 1, 1949

By J. Brett, L. Seigle, L. Castleman, T. Montelbano

Impurity-induced low-temperature recrystallization of cold-worked tungsten was inuestigated with emphasis on the influence of nickel on the reaction. Palladium, nickel, aluminum, manganese, platinum, and iron greatly lower the recrystallization temperature of doped tungsten, which zs normally very high, but the recrystallization temperature of electron-be am zone-refined tungsten wzre is slightly raised by conlacl with nickel. Recrystallization can be induced at low temperature by the presence of solid nickel on the surface of doped tungsten wire, but apparently not by exposure to nickel vapors alone. Approximately 200 ppm of Ni dijjused into 10-mil wires at 1200 from a deposit of nickel on the surface produced total recrystallization, whereas more than 600 ppm of Ni could be absorbed frotn a vapor source without altering the fibrous structure of cold-worked tungsten. Once initiated, nickel-induced recrystallization required a continued source of' nickel for propagation of the recrystallization front. The solubility of nickel in fibrous 10-mil W wire was approximalely 500 ppm at 1150' C, and the activation energy for penetration of the recrystallization front was 52 kcal per mole. In many applications the usefulness of tungsten depends on critical control of its structure. Cold-worked tungsten with the fibrous structure developed by suitable thermo-mechanical treatment has a low, but technologically significant, ductility. It has long been known1 that traces of nickel, and perhaps other metals, are profoundly deleterious in doped tungsten, because they induce recrystallization at low temperature, which produces a brittle, equiaxed grain structure. This effect appears to be an exception to the general observation that recrystallization is impeded and the recrystallization temperature raised by the presence of impurities.2"9 Previous studies7-'' of the annealing and recrystallization of tungsten wire have divided the phenomenon into prior recovery stages, primary recrystallization and secondary recrystallization. The present investigation is concerned principally with primary recrystallization which is defined here as the replacement of the fibrous structure of deformed tungsten by equiaxed grains. The objective of this study was to explore the nickel-induced recrystallization reaction in tungsten and attempt to elucidate its mechanism. As well, an effort to define which other elements give rise to low-temperature-induced recrystallization was carried out. EXPERIMENTAL PROCEDURE The procedure adopted for these experiments was essentially to bring nickel and other elements into diffusive contact with cold-worked tungsten wires. The process of recrystallization was followed as a function of time and temperature by light and electron microscopic observations. First the influence of nickel on the recrystallization temperature of arc-melted, zone-refined, and variously doped tungsten wire was determined by electroplating a deposit of nickel on the surface of the wire and annealing at a variety of temperatures for 3 hr. The chemical analyses of the tungsten wires used in this investigation are given in Table I. The surface of the tungsten wire was etched with Murakami's slution' and approximately 0.005 in, of Ni was deposited from a Watts-type low pH bath14 for the conditions of these experiments. Variations in plating thickness from about 0.001 to 0.005 in. had no discernible influence on the resulting structures. The wires were then annealed in an atmosphere of dry hydrogen to establish the recrystallization temperature. Concurrently, un-plated specimens were annealed to establish the recrystallization characteristics of nickel-free wire. The criterion of recrystallization was that the fibrous structure be completely replaced by equiaxed grains after a 3-hr treatment of temperature. This provided more reproducible results than use of the first recrystallized grain or a fixed proportion of re-crystallized structure as the critical observation. The structures encountered in longitudinal and transverse sections were examined by both light and electron microscopy at magnifications up to X32,000 using parlo-dion-carbon replicas shadowed with platinum for the latter method. Second, the influence of a variety of metals on the recrystallization temperature of 0.010 in. D alumina-silica doped tungsten wire, AW136-64, was determined. The elements were applied by electroplating whenever possible. Alternatively, they were vapor-plated on the tungsten wire and a greater thickness built up by coating with a dispersion of metal powder in nitrocellulose lacquer. Elements not amenable to either of these procedures were merely slurry coated on the tungsten. The recrystallization temperature was determined as above. Third, the nickel-induced recrystallization process in doped wire was studied more closely by electroplating 8 mils of Ni on 65-mil alumina-silica doped tungsten wire, AW153-NS10, and exposing the wire to temperatures of llOO°, 1200°, or 1300°C for various times in a hydrogen atmosphere. A circular recrystallization front, 'Onsisting of equiaxed grains, developed at the periphery Of the coated tungsten wire, and the advance of this front into the fibrous interior was studied. These experiments employed relatively coarse 0.065 in. D wire because the 0.010 in. D wire recrystallized too quickly to permit observation of the pene-

Jan 1, 1969

By A. T. Yu

Two key components make up the core of a rapid excavation operation. They are: the breaking up of the rock and its removal. Owing to the complexity inherent in mechanical rock-breaking and the relative infancy of the art, for a number of years the first of these two components has received virtually undivided attention from the industry. Only recently has some concern been expressed about the technology and the economics of the much ignored second component: muck removal. As the continuous boring machine's percentage downtime continues to trend lower in the future, the need for adequate and more effective materials handling systems in rapid excavation will become increasingly more acute. (1) Recognition of the need for a broader and more far-sighted approach to our problem has been eloquently underscored in the conclusions of the Committee on Rapid Excavation sponsored by the National Research Council: "Ultimate attainment of the desired cost and speed improvements is significantly dependent on recognition of the excavation process as a system whose subsystems are critically inter-related. Substantial amounts of full-scale field testing of integrated driving, muck removal, and support subsystems are required." (2)

Jan 1, 1997

EVERY English-speaking mining, engineer or geologist knows that some terms used by his profession are not rigid but vary regionally; for example: what is called a vein by some, is called a lode by others and is known as a reef to their Australian colleagues. There are parallels in, the German language. Since, in addition, the meaning of some words may change considerably in 450 years-and other words may disappear completely-and not only the terminology but the concepts of a science are subject to drastic changes over such a long period of time, translating the Bergbüchlein posed some interesting problems. Old German texts and glossaries such as C. T. Delius' Anleitung zu der Bergbaukunst (1773), Minerophilus' Neues and Curieuses Bergwercks-Lexicon (1730), and H. Veith's Deutsches Bergwörterbuch (1871) proved useful sources of information when defini¬tions of obscure terms were needed. The task of translating was made even more challenging by the author's personality. As Ulrich Rülein von Kalbe was primarily a physician, his information must have been mostly secondhand. Since the nomenclature of the miners of Saxony, where he gathered his material on silver ores, undoubtedly varied from that of the German miners in Hungary, for instance, who probably supplied him with data on gold ores, it is not astonishing that he is not consistent in his use of some expressions. To give an example: there is every indication that Flöz and schwebender Gang (see footnote p. 21) are used interchangeably in spite of his occasional disapproval of such usage. It is obvious that he was an educated man with a questing and active mind and, although he apologizes-not wholly sincerely, one might suspect-for the simple

Jan 1, 1949

By M. H. Sommer

Many attempts have been made to develop a relation between the tensile properties and the deep-stamping qualities of metals commonly used in deep drawing. These operations are generally performed cold and the metal is always stressed beyond the elastic limit. However, the problem cannot be readily solved without a proper investigation of: (1) the relation between actual stress and actual strain in the plastic range and (2) the stresses that are set up in the metal during the process of deep stamping. Much work has been done in recent years to add to our knowledge on plastic deformation of metals and the shortcomings of the ordinary tensile test, particularly in the plastic range, have been sufficiently recognized. It has been widely acknowledged that the local contraction, which appears in a tensile test after the maximum load is reached, is not a general characteristic of the material but is peculiar to this form of testing. The plastic deformation of materials is explained by the slip of their crystals along certain planes and this rearrangement should be similar whether observed in a tensile, compression or torsion test, and if the results of any of these forms of testing show deviations, it must be due to other influences, as for example the local contraction in a tensile test. For this reason the tensile-test curve as obtained from the measurements taken on a tensile-test machine or registered by an autographic device has been supplemented by the so-called "actual stress-strain curve," which is constructed from the observed tensile-test data by eliminating the effect of local contraction and is in complete alignment with the stress-strain values obtained in a compresison or torsion test. The actual stress-strain curve shows the increase of actual unit stress in relation to unit elongation beyond the yield point and beyond the point of maximum load and indicates clearly the extent of strain-hardening which the ordinary tensile-test curve does not reveal. The following metals have been investigated in this paper and their actual stress-strain curves and, further, their char-

Jan 1, 1934

By Qionghua Zhou, Wei Liu

"Nanocrystalline silver bulk material with average grain size of 20.3 nm was prepared by warmvacuum- compaction method. The as-prepared nanocrystalline silver was characterized by X-ray diffraction (XRD), differential scanning calarmeutry analysis (DSC), thermogravimetric analysis (TG), and 6157 type Electrometer test, respectivily. The experimental results show that the average grain size and microstrain of the nanocrystalline silver are 20.3 nm and 0.088%. The melting point and melting enthalpy are 1228.7 Kand 82.34 Jig, which are lower than that of coarse-grained silver by 6 Kand 22.6 Jig, respectively. The electrical resistivity of nanocrystlline silver increases with higher temperature when the range of temperature is between 233K and 293K. The electrical resistivity at 293 K is 1.475xlO -7 Q·m, which is higher than that of coarsegrained silver by a factor of 9.IntroductionN anocrystaline ( nc) materials or nano structured ( ns) materials are three-dimensional (3 D) bulk materials with average grain size typically smaller than 100 nm. Ne materials have been of great interest for their unique properties, such as superior tensile strength [1-2], high microhardness [3- 4], superplasticity [5-6], magnetically quasi-isotropic [7-8] , and so on, making them one of the most promising nano-scale materials with wide applications. Ne materials with average grain size of 5-10 nm were firstly fabricated by Gleiter et al. [9] in 1980s, using inert gas condensation (IGC) method. Unfortunately, the large surface to volume ratio creates a high surface energy component in the total free energy of the system and results in a metastable state in the materials. Therefore, due to the signfica nt disordered grain boundary regions, nanomaterials are thermally unstable and are subjected to a strong driving force for grain growth. The grain growth even occurred at room temperature [10].The conflict or deviation of measured date, e.g. strength, microhardness, thermal stability, partly due to the grain boundary ratio or the distribution of grain size, and partly derived from imperfections such as voids and microcracks while earlier processing techniques are known to result in incomplete dens:fication [11-12]. Therefore, the higher quality samples produced in subsequently years still show such a general trend."

Jan 1, 2011

Jan 1, 1931

By Michael A. Devane, Neil Duncan

Inclines and tunnels can extend from ground surface to considerable depths traversing a wide range of lithologies. The strata encountered may be affected by loosening and induced stresses at different locations along the route. It is suggested that Phase I of the pre- driving assessment process should include study of the geology, hydrogeology, rock material and rock mass characteristics. A rock mass disruption factor is used to express the ratio of the unconfined strength of intact rock material to the unconfined strength of in situ rock mass. It is suggested that there is a relationship between in situ (secondary) permeability values and the disruption factor, since the permeability of the rock mass is governed by parameters which influence strength. In Phase I1 of the pre-driving assessment, consideration should be given to the prediction of primary loosening which results largely from disturbances to the rock mass arising from the driving process. Also in Phase 11, preliminary assessments are made of the effects of induced stresses and of the geodurability characteristics of the rocks. In Phase 111, the mechanics of various secondary loosening pro- cesses are considered along with their relevance to estimates of stand up time and support requirements. Yield-line analysis is introduced for the study of plastic and brittle type bending deformations. Stand up time and support characteristics are also assessed. In Phase IV, the effects of induced stresses are analysed. It is suggested that even for broken rock in the Yield Zone, the rock mass disruption factor may not often increase above lo which is equivalent to an in situ permeability of 10-1 m/s.

Jan 1, 1983

By Ronald J. Riberich

The Mineral Economics and Management Society (MEMS) held its fifth annual conference in Montreal, Quebec, Canada earlier this year. “The Minerals Industry: Responding to the Global Challenge” was the first MEMS conference to be held outside of the United States. About 125 mining- and minerals-related professionals attended. The MEMS program included six sessions and three distinguished speaker addresses. The session topics included: “Minerals in the Macro economy: Development in Demand,” “Trends in Global Metals Supply: The Producers’ Challenge,” “Global Environmental Issues: Policy Perspectives,” “Global Environmental Issues: Quantitative Analysis” and “Minerals in the CIS: Phoenix or Albatross?” A student session was also offered. It provided a competition for monetary awards for outstanding papers.

Jan 1, 1996

OPEN-HEARTH refractories are not merely an accessory to the furnace. They are the furnace, to all intents and purposes. The steel work of the main structure is merely an open frame which helps to support the refractories; and the regenerators, a necessary part of the furnace system, consist almost entirely of refractories. Not only do refractories constitute the essential part of the furnace, but they also carry the liquid steel all the way 'to the point where it begins to solidify. On leaving the furnace the liquid passes through a refractory runner into a refractory-lined ladle, then through a refractory nozzle closed by a refractory stopper on the end of a rod protected by refractory sleeve bricks. The liquid is sometimes sent through an additional refractory- lined tundish, a supplementary ladle, or a refractory runner for bottom pouring, until it finally enters the iron mold in which it solidifies. Even in the mold, refractory materials are sometimes used to provide a nonconducting "hot top." This series, from runner and ladle to hot top, inclusive, is often referred to collectively as the "pouring-pit refractories." REFRACTORY RAW MATERIALS The raw materials available are best classified into basic and acid types. The principal basic raw materials are magnesite, dolomite, and chrome ore. The principal acid materials are silica in various natural forms, and fireclay. Magnesite. Austria was the principal source of magnesite (MgC03) until recent years, when the Province of Quebec, in Canada, and the states of Nevada and Washington became important sources for the American steel industry. More recently these natural sources have been supplemented by the so-called "sea-water magnesite"-which is the name somewhat incorrectly given to magnesium hydroxide obtained as one of the products

Jan 1, 1951

By Z. T. Bieniawski

A major study was performed on determination of long term strength of coal strata directed to the design of coal pillars to ensure their stability beyond the life-time of a mine. Based on field investigations, numerical modeling and reliable data from 12 case histories, three aspects of time effect in the strength of coal strata were studied; (1) strength reduction based on the concept of volumetric strain estimate from in-situ tests, (2) strength reduction in terms of three failure criteria applicable to coal strata: original Hoek-Brown criterion, modified Hoek-Brown criterion, and Generalized criterion, and (3) long-term strength estimation as a function of coal strata quality RMR based on case studies. From these investigations, an integrated approach to long-term pillar stability is proposed, based on numerical modeling and empirical pillar strength formulation. The values of factors of safety for coal pillars are analyzed in terms of probability of failure and practical meaning for mine design purposes.

Jan 1, 1994

By William G. Freeman

As with most industrial minerals, barite is freight sensitive. This paper is given so that others might gain from the experience of barite companies in reducing their transportation costs. Some of the approaches used were unusual and others standard, but by perseverance considerable savings were realized.

Jan 1, 1973

By Jennifer Young

Presentation Outline ? Introduction ? Aboriginal Inclusiveness ? Common interpretations, practices ? Aboriginal Community Expectations ? Lessons Learned ? Native Code of Conduct Introduction Jennifer Young ? Nestu'et (Mi'kmaq) means: becoming wiser, becoming more knowledgeable Aboriginal Inclusiveness ? Internal hiring strategies (affirmative action) ? Incorporating cultural awareness programs ? Approaches in governmental/organizational policy development Practices in negotiating economic development and fiscal sharing strategies

May 1, 2010

By A. M. Gaudin, D. W. Fuerstenau

IN concentration of certain ores by soap flotation, prevention of quartz flotation is desired; the contrary is true in treatment of some oxide iron ores. Experimental study of the flotation of quartz goes back at least a quarter of a century.' Clean quartz does not float with fatty acids or soaps but does float when activated by one of many metallic salts. Control of pH is important. Broadly speaking the problem of quartz flotation has been approached from the empirical side, as was the related topic of flocculation or dispersion of quartz suspensions? Empirical studies indicated the existence of critical relationships between the additions of collector and activator. These additions were not stoichiometric for the formation of soaps of the activator cation. For example, Gaudin and Rizo-Patrona found optimum quartz flotation at pH 10.6 using barium activation and oleate collection when the molar ratio of oleate to barium was 1 to 1 instead of 2 to 1, as would be called for formation of Ba(OL),. Cooke and Digre" ' found that if calcium is the activator, a minimum quantity of that agent is required for effective flotation when the pH is 11.5. In other words, if the concentration of Na' exceeds 10 -2.5 mols per liter or if the concentration of H exceeds 10-11 mols per liter, the concentration of Ca++ in solution required for quartz activation is increased. This suggests that H+ is much more effective than Na+ on 10-2.5 quartz, perhaps in the ratio ofp or 108. Schuh- mann and Prakash6 studied anew the activation of quartz by barium, calcium, aluminum, and ferric iron. Salts of these metals are activators provided they are in stoichiometric excess over the collector used with them. Alkaline-earth salts are effective only in alkaline circuits. Important as they are in giving data on the effect of various agents on quartz, all these studies fail to give information on the detailed structure of the quartz-solution interface. A beginning in this direction was made by Gaudin and Chang,? who measured the adsorption of radioactively marked barium and laurate ions at quartz surfaces, and by Gaudin. Spedden, and Laxen,8 ho measured the adsorption of radioactively marked sodium at quartz surfaces. Work has also been done by Bell0 n measurement of the adsorption of sodium ion and chloride ion at quartz-solution interfaces. In all these experimental measurements of adsorption, the solid was centrifuged or filtered from the bulk of the liquor with which it had been associated; and the composition of the solid surface was ascertained by analysis, after allowance was made for the ionic composition of the liquor included with the centrifuged solids on the assumption that it is identical to the bulk liquid. Adsorption measurements give only the total amount of collector adsorbed at the quartz-solution interface; they give no indication of the distribution of these adsorbed ions at the interfacial layer. It is the ionic structure of the solid-solution interface and its importance to flotation that is the subject of this paper. The structure of this interfacial layer can be investigated by means of electrokinetic methods so that by combining electrokinetic studies with adsorption measurements, a more complete picture of the quartz surface may be obtained. The following studies were made to ascertain how electrolytes used in the soap flotation

Jan 1, 1956

By Philip K. Chan

Batu Hijau is a new copper and gold mine located on the island of Sumbawa in the Republic of Indonesia. This paper details the design and construction of the Batu Hijau overland conveyor, one of the most challenging efforts of the project. The 1.8 m wide, 5.6 km long conveyor has a design capacity of over 10,000 mtph and carries primary crushed ore through the steep mountains of Sumbawa, which necessitated a 160 m vertical downhill section, a 75 m vertical uphill section, ten vertical curves and one horizontal curve.

Jan 1, 2000

By M. E. Lombardi

ThE Coalinga oil field is located on the west side of the San Joaquin Valley, California. The structure is in general a monocline, the edges of the oil horizon resting on the foot hills and dipping gently toward the east. One prominent anticline occurs plunging southeast. The earlier drilling was done in the foot hills comparatively near the outcrop and the wells were shallow. The sands were followed eastward and, in the case of the anticline, along the plunge, the wells becoming deeper and deeper until the depth of 4,000 ft. was reached and passed. There is nothing to show that the oil will not be found in quantity at still greater depth. In fact, some of the best producers have tapped the sand at close to 4,000 ft. The recovery of oil still farther to the east, and therefore at greater depth, seems to be mainly a question of drilling. In this territory the formations drilled through are chiefly sands and shales; they will not "stand up" in an open drilling hole; the casing has to be carried close to the bit, and it is always difficult to keep the casing free for any considerable distance. Ability to carry casing of comparatively large diameter without conductor pipes for distances of 2,000 or 3,000 ft. or over is desirable in such territory chiefly for two reasons. It makes it possible to enter the oil sand with a pipe of ample diameter; it eliminates one or more expensive strings of casing which act only as conductors for the water string, and furthermore, in territory where waters are encountered which corrode steel rapidly, it makes possible the construction of a rust- and alkali-resisting water string. It is always desirable to shut off top waters, which may lie within 100 ft. or less of the oil sand, with 10-in. pipe. Where the depth is so great that a practical weight of 10-in. pipe will not withstand the probable collapsing pressures, 81/4 in. at least is desirable. About the limit of rotary drilling to date in California seems to be the setting of the 10-in. string at 3,200 ft., although the rapid advance in rotary work during the past year seems to indicate that this depth may soon be increased. It is my purpose now, however, to treat only of cable-tool drilling. The problem is to reach a depth of 4,000 ft. or more with a string of

Jan 1, 1915

By T. A. P. Sankar, S. Gundiah, Pradip, R. A. Kulkarni

Two modified polyacrylamide flocculants, namely polyacrylamide with glycolic acid functionality (PAMG), and a copolymer of acrylamide with N-acryloyl-[T]- aminobutyric acid (HPVP), were synthesized, characterised and evaluated for selective separation in apatite/quartz and apatite/dolomite/calcite systems, respectively. PAMG flocculant was found selective in the separation of tricalcium phosphate (TCP) from its mixtures with quartz at acidic to neutral pH range. The selectivity deteriorated at alkaline pH. In contrast, polyacrylic acid (PAA) flocculant was found most effective only in the alkaline pH range. HPVP flocculant (even though flocculating all three minerals namely apatite, dolomite and calcite) was observed to be quite selective for the separation of calcite from apatite-dolomite minerals in single mineral tests in the presence of sodium hexametaphosphate dispersant at neutral pH. There was, however, no selectivity observed during tests on synthetic mixtures. This loss in selectivity is attributed to the phenomenon of hetero-flocculation, as reported earlier, for separation in an apatite-dolomite system with polyethylene oxide.

Jan 1, 1993