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By A. Gene Collins, Cynthia A. Pearson, Cathy J. Waters

The chemistry of selenium and tellurium is discussed , along with a method of preparing a synthetic oilfield brine , an oilfield brine sampling method , and methods for determining selenium and tellurium in complex oilfield brines . Selenium either can be reduced to the elemental form with sulfur dioxide and determined semiquantitatively by color comparison of the red amorphous form or can be converted to selenite and determined quantitatively by reacting it with 3,3 ' - diaminobenzidine and obtaining its spectral absorbance at 420 mu . Tellurium can be reduced to the elemental form with hypophosphorous acid , and the spectral absorbance of its red hydrosol can be measured at 400 mu . Less than 0.05 mg / 1 of selenium and 0.1 mg / 1 of tellurium can be determined by the described methods .

Jan 1, 1964

By O. G. Olvera

"Refractory sulfidic ores consist of materials in which gold occurs finely disseminated within metallic sulfides or forming solid solutions, with pyrite and arsenopyrite being the two sulfides most commonly associated with gold. Typical cyanide operations show poor performance and require oxidative pretreatments to increase gold recovery. Pretreatment alternatives include roasting, pre-aeration, acidic and alkaline high pressure oxidation, and bacterial oxidation. The presence of arsenic, however, introduces a serious disadvantage to the use of roasting and bacterial leaching, while high pressure oxidation involves high capital costs. This work focuses on evaluating the effect of the addition of a carbon resin as a sulfur collector on the oxidation of different arsenopyrite concentrates under atmospheric tank leaching (ATL) conditions. The addition of the resin improved the oxidation of sulfides and favored the formation of elemental sulfur over the generation of sulfate. The use of AF5 in ATL resulted in higher gold recoveries under standard cyanide carbon-in-leach and thiosulfate leaching.INTRODUCTION Refractory sulfidic ores consist of materials in which gold occurs finely disseminated within metallic sulfides or forming solid solutions, with pyrite and arsenopyrite being the two sulfides most commonly associated with gold. Gold is not readily accessible to solutions in these types of ores and typical cyanide operations show poor performance, thus making the use of oxidative pretreatments a requirement to increase gold recovery. Pretreatment alternatives include roasting, pre-aeration, acidic and alkaline high pressure oxidation, and bacterial oxidation. The presence of arsenic, however, introduces a serious disadvantage to the use of roasting and bacterial leaching, while high pressure oxidation involves high capital costs. The use of carbonaceous materials to enhance the dissolution of sulfides is not novel, and leaching additives such as coal, activated carbon and carbon powder have been considered for the improvement of bioleaching, atmospheric leaching, and pressure oxidation leaching processes. However, this type of technology has been focused mainly on the recovery of copper from copper concentrates containing chalcopyrite with less attention paid to other sulfides."

Jan 1, 2017

By Jalal Vakili

In designing very large excavated slopes which are becoming increasingly common in both mining and civil engineering projects, the most important decision of the engineer is the selection of a slope angle. The purpose of the geotechnical study of the slope is to ensure reasonable stability of the slope in the most economical way. Because the rock mass composing each slope is unique, there are no standard solutions for slope stability analysis. A practical solution is formulated from the basic geologic data, engineering properties of the rock, geometry of the slope, and ground water observations. Stability analysis consists of analyzing the forces causing and resisting slope failure. There are several methods of slope stability analysis. The limit equilibrium method evaluates the overall stability of the sliding mass just on the verge of slip, using some or all of the three equations of static equilibrium of a plane problem. The stress-strain relationships of the rock mass are not considered. Method of analysis include the assumption of the shape of the slip surface. Peterson (10) introduced the Swedish method of analysis in 1916, which is based on cylindrical sliding surfaces. Fellenius (4) in 1926 extended this method and introduced the method of slices. This method was refined by Bishop (I) in 1955 and later used by Morgenstern and Price (8) in 1965. In many cases layers of extremely soft strata or strata weakened by neutral stress cause failure to take place by translation along plane of weakness instead of by rotation on a circular surface. In this paper, a slope with a horizontal layer of weak meterial is selected for analysis. This is a usual case for open pit lignite mines where lignite seam may be non-cohesive and 'weaker than the overburden rock or a soft clay layer underlies the seam. It is also a common case of rock fill dams supported on a foundation stratum of clay where the strength of the clay layer is less than that of the rock fill. It is shown that utilizing this method, the location of potential failure surface and the value of the minimum factor of safety can be calculated directly and the trial computations of factors of safety for a number of assumed failure surfaces are not necessary.

Jan 1, 1982

By E. J. Matson

Under the investigation for critical and strategic minerals the Kaiser mine, formerly the Baxter fluorspar property, in northeastern Mineral County, Nev., was explored. The work comprised excavating 32 trenches averaging 90 feet in length, 8 feet in width, and 1 1/2 feet in depth. The trenches were excavated across the strike of the ore body to enable the engineer to spot the diamond-drill holes; 7 such holes were drilled, aggregating 3,276 linear feet. A total of 20 core samples and 107 sludge samples was taken. The work under this program indicated that the fluorspar southwest of the deposit extended laterally and also at depth at least 250 feet below the 400-foot level. INTRODUCTION The Kaiser fluorspar deposit is in the northeastern portion of Mineral County, Nev. Mining was begun about 1928, and the property has been a consistent producer of both Acid- and Metallurgical-grade fluorspar. The mineralized zone has been developed along a strike length of about 2,000 feet and to a depth of over 700 feet along the dip.

Jan 1, 1957

By S. L. Weber, V. Castranova, D. E. Banks, J. K. H. Ma, Y. Rojanasakul, J. Y. C. Ma, M. Bhat

"The mechanism of bleomycin-induced pulmonary fibrosis is not ye: clear. Recent studies have shown that alveolar macrophages (AM) can be stimulated by bleomycin in vitro releasing inflammatory cytokines, suggesting that the interaction of bleomycin with AM is an important step in the drug-induced fibrotic process. Bleomycin is known to bind DNA and generate oxygen radicals through complexation with Fe2+ and oxygen. To provide,more insight into the cellular oxidative property of bleomycin, v.s have developed a fluoromicroscopic method using 2',7'-dichlorofluorescin diacetate (DCFHDA) as an oxidative fluorescence probe to study the deomycin-induced intracellular oxidation in rat AM and the inhibition of the oxida¬tion by taurine, a compound known to inhibit the bleomycin-induced fibrosis. Bleomycin at 5 to 20 ug/ml has a moderate stimulatory effect (1.87- to 2.66-fold) on the secretion of superoxide anion. A high concentration of bleomycin (20 ug/ml), however, inhibits cell response to zymosan-induced secretion of superoxide anion. At 4 ug/ml, bleomycin has no effect on cell membrane integrity or morphology but results in a significant increase in intracellular oxidation. This oxidative process is Fe2-,-dependent and is accompanied by an increase in intracellular calcium (35 nM). Both the intracellular oxidation and calcium rise induced by internalized bleomycin are inhibited by pretreatment of cells with varying concentrations of taurine (25, 125, and 187.5 uM). The inhibitory effect on intracellular oxidation .vas found to be 36, 57, and 60%, respectively. These results demonstrate a stimulation-inhibition relationship between bleomycin and taurine on re cellular oxidation at a subcytotoxic dose of bleomycin, suggesting that the oxidative effect of the intracellular bleomycin-Fe2 complex is important in the initiation of the fibrotic process. — Environ Health Perspect 102 (Suppl10):91-96 (1994) IntroductionThe pulmonary system is most susceptible to oxygen radical-induced diseases due to its constant exposure to the highest oxygen tension, and the potential encounters with oxidant gases such as ozone, nitrogen oxides, and toxic doses of dust particles. The lung is also a well-perfused organ and thereby vulnerable to the effect of circulating xenobiotics such as paraquat, and, bleomycin, which is known to cause pulmonary injuries (1). Alveolar macrophages (AM), which act as a means of defense by phagocytizing inhaled dust particles and microorganisms while increasing production of reactive oxidative species, have been shown to play an important role in mechanisms leading to oxidative lung injury and fibrosis (2-4)."

Dec 1, 1995

By Robert C. Stephenson

Large deposits of titaniferous magnetite occur associated with anorthosite and gabbro in the Lake Sanford area, Essex County, New York. The ore, gabbro, and anortbosite show consanguineous relations. Anorthosite grades through gabbroic anortbosite into gabbro but is locally intruded by gabbro. Structural and petrographic evidence suggests that gabbro was differentiated from anorthosite by filter pressing. Field and laboratory study of ore occurrences indicates that an ore residuum concentrated in the gabbro through magmatic segregation' by normal crystallization and flowage. Ore occurs as bands which grade into gabbro, and also as large masses which replace anorthosite. Ore in the gabbro is finer grained and richer in ilmenite than ore in anorthosite. Introduction The Lake Sanford area lies in the heart of the Adirondack Mountains, in the southeast portion of the Santanoni Quadrangle (Fig. I), and there are four ore bodies in the area immediately surrounding Lake Sanford. The area lies 30 miles by highway from the railroad at North Creek. The deposits were discovered in 1826, and from then until 1858 iron was produced in small quantities. They were idle from 1858 to 1906. Between 1906 and 1913, extensive development work was carried on. These early attempts to produce iron ore were thwarted by transportation difficulties and by the titanium content of the ore, which, ironically, has been the element responsible for the present development. In 1941 the National Lead Co., Titanium Division, developed the Sanford Hill ore body and is now producing ilmenite and magnetite concentrates.18 The Defense Plant Corporation is extending the railroad to the property from North Creek and is building a sintering plant to treat the magnetite concentrate. Investigations OF the Deposits* Early studies of the Lake Sanford titaniferous magnetite deposits were made by Emmons in 1842,l2 by Kemp, in 1897-98'0 and by Newland in 1908.22 Singewald26 and Osborne23 considered these deposits along with numerous other titaniferous magnetite deposits in 1913 and 1928, respectively. None of these reports entailed a detailed study of the ore occurrence in this area. The present study was begun in 1940. Seven months were spent in the field, and considerable time was spent in labora-

Jan 1, 1949

By Robert C. Stephenson

Large deposits of titaniferous magnetite occur associated with anorthosite and gabbro in the Lake Sanford area, Essex County, New York. The ore, gabbro, and anortbosite show consanguineous relations. Anorthosite grades through gabbroic anortbosite into gabbro but is locally intruded by gabbro. Structural and petrographic evidence suggests that gabbro was differentiated from anorthosite by filter pressing. Field and laboratory study of ore occurrences indicates that an ore residuum concentrated in the gabbro through magmatic segregation' by normal crystallization and flowage. Ore occurs as bands which grade into gabbro, and also as large masses which replace anorthosite. Ore in the gabbro is finer grained and richer in ilmenite than ore in anorthosite. Introduction The Lake Sanford area lies in the heart of the Adirondack Mountains, in the southeast portion of the Santanoni Quadrangle (Fig. I), and there are four ore bodies in the area immediately surrounding Lake Sanford. The area lies 30 miles by highway from the railroad at North Creek. The deposits were discovered in 1826, and from then until 1858 iron was produced in small quantities. They were idle from 1858 to 1906. Between 1906 and 1913, extensive development work was carried on. These early attempts to produce iron ore were thwarted by transportation difficulties and by the titanium content of the ore, which, ironically, has been the element responsible for the present development. In 1941 the National Lead Co., Titanium Division, developed the Sanford Hill ore body and is now producing ilmenite and magnetite concentrates.18 The Defense Plant Corporation is extending the railroad to the property from North Creek and is building a sintering plant to treat the magnetite concentrate. Investigations OF the Deposits* Early studies of the Lake Sanford titaniferous magnetite deposits were made by Emmons in 1842,l2 by Kemp, in 1897-98'0 and by Newland in 1908.22 Singewald26 and Osborne23 considered these deposits along with numerous other titaniferous magnetite deposits in 1913 and 1928, respectively. None of these reports entailed a detailed study of the ore occurrence in this area. The present study was begun in 1940. Seven months were spent in the field, and considerable time was spent in labora-

Jan 1, 1949

By Bengt T. Andersson

Outokumpu Consulting Engineers, Outokumpu Oy SF-02200 Espoo 20, Finland This paper describes experiences from some operating non-ferrous flash -smelters and focuses on the advances in smelter byproduct and gas treatment engineering design. In this context a summary is given of the specific technical and economic benefits achieved-by flash -smelting technology and oxygen enrichment. The paper will also briefly outline a few new process and equipment developments.

Jan 1, 1983

By F. Brost

In 1976, a decision was made to install a conveying system to transport ore 10.3 km (6.4 miles) from the new Eisenhower Partnership Mine to Twin Buttes. The system, supplied and installed by Cable Belt Limited, of England, represents a radical departure from conventional conveyor systems. The driving tension is applied through two endless wire ropes while the belt acts only as the carrying medium. Features of the system are a single 2240 kw (3000 hp) drive and a 60° angle bend. Construction was completed in two years. Full production was attained after several months' operation.

Jan 1, 1979

By S. M. Bradshaw, E. Charikinya

"Microwave induced cracks have the potential to enhance metal recovery from coarse sphalerite particles in heap leaching operations by creating new crack surface areas for lixiviant and enhancing value mineral exposure. The mode of fracture and the extent of mineral exposure due to microwave induced cracks have not yet been investigated. The objective of this study was to determine the extent of particle damage and mineral exposure in microwave treated particles. This was done using X-ray computed tomography (XCT) and image analysis techniques. XCT analysis was conducted on small (–5+4.75 mm), medium (–16+9.5 mm), and large (–25+19 mm) sphalerite ore particles before and after microwave treatment (MT). Geometrical properties, such as volume and surface area of each mineral phase in each particle was determined from the XCT reconstructed images using VGStudioMax image analysis software. These geometrical properties were used to calculate the interfacial areas of sulphide mineral grains in microwave treated particles before and after MT. The ratio of specific interfacial area after MT to specific interfacial area before treatment was used as an indicator of the degree of preferential grain boundary fracture. The results showed significant grain boundary fracture after MT at all sizes. For small sized particles, about 31% of the interfacial area was lost compared to 23 and 16% for medium and large particles, respectively. The results also showed an increase in the degree of mineral grain exposure of 28, 26, and 15% for small, medium, and large particles, respectively, after MT. These results provide experimental evidence supporting improved mineral exposure due to MT. INTRODUCTIONFor some years it has been suggested that microwave treatment (MT) of ores might result in preferential grain boundary fracture that would have benefits such as improved grain exposure and particle weakening. (Kingman, 2006). Most of the experimental work investigating the application of microwaves to mineral processing flow sheets has focused on assessing the benefits of applying microwave technology to flow sheets consisting of size reduction and mechanical flotation cells (Kingman et al., 2004). Experimental studies have shown that coarse crushing during tertiary grinding of microwave treated ore resulted in a better liberated coarser flotation feed (Scott, Bradshaw, & Eksteen, 2008). It has been suggested that improved liberation in milled flotation feed, was due to the presence of grain boundary fracture in microwave treated particles. However, this improvement in coarse particle liberation does not necessarily translate to a significant improvement in downstream flotation recovery (Kobusheshe, 2010). This is as a result of the size limit to the flotation of coarse material, due to detachment forces acting on particle-bubble aggregates, which increase as the particle size increases (Jameson, 2012). Current conventional, mechanically agitated flotation cells are not designed to float coarse material (Jameson, 2012). Hence it has been difficult to show the downstream processing benefits of applying microwaves to ores processed by comminution followed by flotation (Kobusheshe, 2010). It is clear from investigations carried out so far that inappropriate downstream exploitation of microwave treated ore would fail to realise a meaningful process benefit (Kobusheshe, 2010; Ali & Bradshaw, 2011)."

Jan 1, 2016

By Joseph Gambogi

In 1998, approximately 57,000 tons of titanium metal was consumed in the form of mill products (1). Only about 5% of the 4 million tons of titanium minerals consumed each year is used to produce titanium metal, with the remainder primarily used to produce titanium dioxide pigment. Titanium metal production is primarily based on the direct chlorination of futile to produce titanium tetrachloride, which is then reduced to metal using the Kroll magnesium reduction process. The use of titanium is tied to its high strength-to-weight ratio and corrosion resistance. Aerospace is the largest application for titanium. In this paper, we discuss all aspects of the titanium industry from ore deposits through extraction to present and future applications. The methods of both primary (mining of ore, extraction, and purification) and secondary (forming and machining) operations will be analyzed. The chemical and physical properties of titanium metal will be briefly examined. Present and future applications for titanium will be discussed. Finally, the economics of titanium metal production also are analyzed as well as the advantages and disadvantages of various alternative extraction methods.

Nov 26, 1999

By S. Lim, G. Walsh, V. Romero

The cable television show, Mythbusters, contacted the New Mexico Institute of Mining and Technology requesting a pressure gauge to be used in underwater testing. The requirements for the gauge were: it must be passive (i.e. require no power to function), it must indicate when a certain, pre-determined pressure was reached, and that indication was to be visual. A pressure gauge was developed, using standard, commercially available rupture discs, set to burst at 500 psi. Underwater testing was conducted using a 400 lb Pentolite charge. Test devices were set out at ranges from 50 to 200 feet from the seat of the blast. The rupture discs showed a lethal range up to 100 feet, but not at 150 feet. This result matched well with the behavior predicted through modeling and simple shock physics calculations. Additionally, the geometry between the incoming shock and the pressure gauge did not seem to have a strong effect on gauge performance.

Jan 1, 2009

By Edward E. Johnson

The principal purpose of this study was the development of an engineering and economic model of a hypothetical large-scale open pit gold mining operation. The guiding concept in developing the model was the idea that, through study of a number of such models, it would be possible to evaluate a mineral property and to make reasonable estimates of the benefits to be derived from research in mining and metallurgy. The model by use of a computer is able to produce results easily and quickly when cost factors are varied. Cost factors may be varied as a result of assumptions of improved technology or of assumptions of assuming different approaches or methods to accomplish a particular segment of the mining or processing operation. The discounted cash flow rate of return was used to measure the effect of changes in costs or expected revenue. In this study, assumptions based on past processing practices were made in an effort to reduce costs of processing the ore These assumptions were: (1) Eliminating the low-grade cyanide circuit; (2) reducing the quantity of material to be processed by screening after crushing; and (3) using a combination of assumptions (1) and (2). All three assumptions resulted in reduced capital investment and operating cost that caused substantial increases in the rate of return.

Jan 1, 1968

By N. V. Ramana Murthy

Utilisation of Low-Grade Iron Ore Fines after concentration not only helps in conservation of the mineral wealth, but also substantialsly improves the economics of iron ore mining. There has been need to develop suitable beneficiation process for upgradation of low-grade iron ores towards their rational utilisation. Presently the circuit adopted for processing iron ores has limitations in reduction of alumina. The depletion of high-grade reserves, utilisation of low-grade reserves coupled with in-creasing market pressure for improved product quality necessitates re-examination of the process flow sheets and evaluate alternative or supplemental processing routes. The main objective of the Process amenability studies for utilisation of Low-Grade Iron Ore Fines (-10mm) is to get Pellet grade concentrate with +65% Fe (min), SiO2 1.8% (max), Al2O3 1.8% (max) and other proportionate constituents by adopting suitable beneficiation techniques and to collect the relevant data (Quality and Quantity of the Products) for the process development. In an effort to formulate a conceptual process flow sheet, the Process amenability studies for utilisation of Low-Grade Iron Ore Fines (-10mm), which is lying at a mine site in India, samples were collected and taken up for the study. The efforts of R & D of NMDC are discussed in this paper. Low-Grade Iron Ore Fines (-10mm) sample assayed 60.10% Fe with 3.48% SiO2 Aland 4.48% 2O3from 40 microns to 300 microns. The sample consists of hematite as the chief ore mineral followed by minor amounts of maghemite. The gangue minerals include quartz and ferruginous clay in which quartz occurs as medium grained where as ferruginous clay occurs as fine to sub microscopic size mineral. The economical processing route evolved out of the studies finally could yield a final concentrate constituting 58.63% by weight along with Iron unit?s recovery of 63.51% assaying 65.10% Fe with 1.48% SiO2 and 1.85% Al2O3route that adopted comprises the following operations. Making slurry in a sump pump followed by grinding in close circuit with 48mesh size Screen. The -48 mesh size product was subjected o the Cycloning to remove slimes. The Cyclone Underflow product was subjected to Floatex Density Separation (FDS) to separate fine heavy minerals from the gangue minerals. The FDS Underflow was collected as concentrate. The FDS Overflow product was further subjected with Wet High Intensity Magnetic Separation (WHIMS) to recover more Iron units as magnetics. A conceptual process flow sheet was evolved, which may become the prelude to the subsequent finalisation of the process flow sheet for commercialisation.

Jan 1, 2014

By Baohua Guo, Xuelin Yang, Tingkan Lu, Hailin Sun

The work presented in this paper mainly involves two parts. Firstly, the fundamental characteristics of the high pressure carbon dioxide gas fracturing technique (CO2 technique), including, a proposed method of TNT equivalence calculation, which is used to calculate the TNT equivalence of discharge of CO2 technique, and the comparison of the explosion volume generated by dynamite and expansion volume of liquid carbon dioxide is conducted to show the differences of fragmentation capacity between the two of them. Secondly, the coal seam fragmentation mechanisms of CO2 technique are proposed, including, 1) Gas jet cutting and penetration by shaped charge, 2) Gas volume expansion by changing phases of carbon dioxide, 3) Coal seam softening by destress blasting and 4) Coal seam fragmentation by discharge vibration, associating with the mechanisms, the equations for calculating fragmentation radius are developed and verified.

Jan 1, 2017

By g. Caproni

The main constituent of the feed to the "Sulphide Section" (31 t/h), in the F. Sartori Plant (6000 tid) of the Miniere di Mon)eponi(Sardinia), is the ore of the Campo Pisano -Funtanaperda Mine (1 ? Difficulties have always been experienced in the treatment of this ore, owing to the extramely fine Pyrite-Sphalerite intergrowth and to the high Pyrite and soluble salts contents. The first mentioned difficulty was overcome with a rather complex flowsheet (see fig.1A and lB)(2); the others with a reagent combination that required a pH of 11 in a pulp loaded with soluble salts. This meant high consumption of alkalizer, and also of the other reagents; furthermore the alkalizer had to be mainly NaOH with only minor amounts of lime, because the latter tended to depress not only the pyrite but also the middlings, which were supposed to float. With dialchylditiophosphate alone as a collector, a lower pH could have been used, but a certain amount of amylxanthate was indispensable to promote flotation of the middlings. On the other hand, a bulk-flotation of sphalerite and pyrite at low pH could not be very advantageous on account of the high pyrite content in the feed(3).

Jan 1, 1971

By Louis Frost

"A FIRE which forced the sealing -of the east side of Dominion No. 16 Colliery in the Town of New Waterford, Nova Scotia, occurred on October 6th, 1952 (Figure 1).So far as can be ascertained, the fire was first noticed in the roof of No. 7 East Lateral, after a brushing shot had been fired in the pavement. There appears to .be no doubt that this shot •blew out, igniting a small feeder in the roof.Regular air measurements and air samples, taken over a long period prior to the fire, indicated that the ventilation was adequate, for at no time had the percentage of CH4 in the general air current exceeded one per cent in this location. The last regular monthly samples and air measurements, taken at the end of September, showed the condition of the ventilation to be:Return at the Top of No. 8 East WallQuantity .... 27,700 cu. ft. per min.CH4 .......................... 0.32 per centC02 ................................ 0.10 per centHowever, in the week preceding the fire the mine examiner on four occasions had reported small feeders of gas at the face of the brushing in No. 7 East Lateral.Figure 2 is a diagram of the working place where the shots were fired. The face brushing had been shot down at 3 :45 p.m. and cleaned up. Two 'hurdle screens' had also been erected, one close to the face brushing and the other fifteen feet from the face."

Jan 1, 1953

By Ewald H. Kurt

The story of America's progressing standard of living is the story of machines. The automobile, the airplane and the telephone for example have made our transportation and communication systems what they are today. Even they depend in turn on another machine -- the rock drill. By making it possible to economically mine and quarry minerals in large quantities, this versatile machine supports virtually every American industry relying on the earth for its buried raw materials. And, like all machines, the rock drill's mechanical evolution was stimulated by production demands placed upon it. All percussion drills are mechanized versions of the original drilling unit -- man, Figure - illustrates a double jack team at work before the turn of the century. The man with the sledge hammer is the impact device while the man sitting is the rotation mechanism and feed motor. The first drifter drills (Figure 2) performed the same function but with increased mechanical efficiency. A piston controlled by a valve produced impact. A built-in ratcheting mechanism provided rotation and a hand-cranked screw provided feed thrust. As the industrial revolution proceeded into the twentieth century, the demand for raw materials stimulated refinements of all recovery machinery, including rock drills. As drills became heavier and more powerful, a mounting (or carrier) had to be provided to move the drill from hole to hole. This resulted in the development of the wagon drill (Figure 3). Propelled by muscle power, the wagon drill was for years the standard tool of the surface drilling industry (Figure 4). As drills penetrated faster and as labor increased in cost, the time consumed in nondrilling peripheral operations had to be

Jan 1, 1977

By H. W. St. Clair

In about 1930, Degussa applied for a patent on a process for the of oxides, carbides, sulfides, and other nonmetallic impurities by filtration in the molter state. The filtering media listed were wire screen, coke, and ceramic materials, and quartz. It was also suggested that filtration might be combined with chemical reaction between the metal and the filter medium or that might be added to the system. No patent was granted on the general scheme, but several years later a patent was granted on a continuous process purification of crude light metals, especially or alkali earth and their alloys. The melt was stirred at 1 temperature at which the impurities (such as oxides and salts) remained solid and the metal was drawn through a filter tube. The impurities collected under the filter and were removed by a screw conveyor. Crude sodium was purified by this process in Degussa's Knapsack plant. During the last war, when the refining of scrap became a very urgent Problem in Germany, experimental investigations were extended to separation of other metals and metallic compounds by filtration. Preliminary experiments seemed to confirm the opinion of Dr. L. Weiss that the principles of wet chemical filtration might be applied to a great extent in the purification of metal and alloys.

Jan 1, 1949

By F. W. Warnaars

Chanarcillo is a historically well-known silver deposit which produced over 100 million ounces. High grade vein-type mineralization is confined to a prominent set of nearly vertical, NNW to NE fractures that intersected limestones, andesites and tuffs of Early Cretaceous age. A significant amount of disseminated silver mineralization extends laterally outward from the fractures for considerable distances in pyritic carbonaceous limestones, whereas more competent volcanic beds rarely contain lateral mineralization. Local exposures of skarns are mostly barren. Silver and minor base metal mineralization was probably formed peripheral to a granodioritic intrusion inferred to exist at shallow depth. Part of this intrusion is exposed nearby where it contains significant hydrothermal mineralization and alteration. This intrusion was dated at 83.8 m.y.

Jan 1, 1987