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By Jim Freeman

After testing 30 fourth year mechanical trade school students with our final mechanical apprentice test, only one passed. ?Most western technical trade school students tested ?Test result average was 52% ?NMC graduating apprentice average is 78% (75% passing requirement) ?Our mechanical test has 200 questions; Electrical test 110 questions

Jan 1, 2010

By R. L. Jones, H. Conrad

The effects of gain size on the room-temperature tensile properties of commercial(A- 70)-purity and iodide-purity titanium were investigated by concurrent tensile testing and thin-foil electron transmission studies. The mechanical tests showed that the effect of grain size on the yield, flow, and fracture stresses could be expressed by relations of the Hall-Petch type. The magnitude of the grain size effect on the yield stress was larger for commercial-purity than for high-purity titanium, but in both materials it was intermediate between that typically observed for fcc and for bcc metals. The effect of strain on the gain size sensitivity of the flow stress was found to reflect the grain size dependence of strain hardening. The electron transmission study indicated that the tensile behavior could be accounted for in terms of the dislocation densities and distributions formed during deformation. It was concluded that the effect of grain size on strength could be attributed to a relationship between grain size and the dislocation densities generated in initiating and sustaining plastic flow, the difference in stress levels being due to strain hardening. The relationships between recrystallized grain size, uniaxial tensile properties, and dislocation substructure have not been explored in any detail for a titanium. With titanium and its alloys finding increasing applications in aerospace systems, such information has become essential. The research described in this paper had two objectives: first, to document the effect of grain size on the yield, flow, and fracture stresses of unalloyed a titanium by the tensile testing of recrystalliied specimens at room temperature; second, to attempt an interpretation of the mechanical test behavior in terms of the dislocation structures formed on deformation, as observed by transmission electron microscopy of thin foils prepared from deformed tensile specimens. The observations reported here are restricted to room-temperature deformation; the effect of temperature on the yield and flow stresses of a titanium and the athermal nature of the contribution of grain size to the flow stress have been discussed elsewhere.1"3 EXPERIMENTAL DETAILS Two purity grades of unalloyed titanium have been investigated: Crucible Steel A-70, a typical commer- cial-purity product, and a high-purity iodide grade supplied by the Foote Mineral Co. Chemical analyses for interstitial impurity contents are given in Table I, together with values for the total interstitial atom fractions in terms of oxygen equivalents, which were calculated by the method outlined previously.4 ,5 According to the manufacturer's nominal analysis, the A-70 grade also contains about 3700 ppm of Fe. The A-70 grade was supplied as 1/4-in.-diam centerless-ground rod. The iodide grade was supplied as crystal bar which was consolidated to approximately 1/4-in.-diam rod by a single, rapid, molten zone pass, using electron beam heating. The 1/4-in. rods were cold-swaged to 0.078-in.-diam wires and 2-in. lengths were recrystallized in a vacuum of -5 x 10-5 torr, giving grain sizes in the range 0.8 to 30 . The thermal treatments and resulting grain sizes are summarized in Table 11. Since there was in no case any obvious sign of a bimodal dis tribution of grain sizes, the grain size values quoted in Table I1 are those obtained from mean linear intercept measurements involving >I00 grains. For the two coarse grain sizes the measurements were made using conventional optical techniques. It was noted during these determinations that the etchants used (10 pct HF; 30 pct HN03; 60 pct H20 and 2 pct HF; 2 pct H202; 96 pct H20 were both tried) etched grain boundaries very nonuniformly and optical polarization effects had to be employed to reveal boundaries which might otherwise have been missed. It was found that this problem became more acute with the finer grain sizes as the usefulness of polarization diminished.

Jan 1, 1970

By R. E. Smallman, J. C. Terry

J. C. Terry and R. E. Smallman (Llniuersity of Birmingham, England)—In a recent publication53 Wood and Westbrook have reported the results of an investigation of the tensile behavior of fl-phase AgMg alloys. These results agree in broad outline, but differ in the details, with those obtained in the above laboratory and, consequently, some discussion of their paper would seem appropriate. In our experiments, tests were carried out on extruded wires, 2 mm diam, in a hard-beam tensile machine, and while an oil bath was used for the tests up to 150°C, above this temperature the oil bath gave rise to serious contamination of the specimens and hence tests above 150°C were made in vacuo. This procedure is different to that adopted by Wood and Westbrook. The ß-phase alloys exhibit differences in mechanical behavior when they are tested in different temperature ranges. In agreement with Wood and Westbrook, three characteristic ranges are observed which may be classified as low, intermediate, and high temperatures, respectively. Our experiments show that in the low-temperature region, the shape of the stress-strain curves is similar to that reported. However, in addition, it is observed that the temperature at which the low-temperature region ends is markedly dependent on strain rate, and increase with increasing strain rate as shown in Fig. 18. The temperature at which a transition from the low to the intermediate temperature takes place is about 0.4 to 0.45 of the absolute melting point, Tm. This transition temperature coincides with that at

Jan 1, 1963

By Shannon Studden, Angela King, Allan Koski

Cliffs Natural Resources is an international mining and natural resources company with over 160 years of history. A member of the S&P 500 Index, the company is a major global iron ore producer and a significant producer of metallurgical coal. Throughout its history, employees have been the foundation of the company’s success, which has long embraced a focus on continuous business improvement.

Jan 1, 2014

By E. J. Ostrowski

The Bureau of Mines experimental blast furnace, Bruceton, Pa., was operated to determine the feasibility of replacing part of the burden coke requirements with solid fuels injected directly into the smelting zone. This report describes preliminary experiments and information resulting from such an interchange. These experiments were made on an all-sinter burden, using two parts sinter to one part fuel. Anthracite fines were injected intermittently into the smelting zone of the furnace by compressed air through auxiliary tuyeres. The interval between injection periods ranged from 5 to 15 minutes. A maximum of 28 percent of the stock column coke bur-den was replaced. This percentage replacement caused furnace malfunction, but the overall percentage of these experiments indicated that 20 to 24 percent of the coke requirements could be replaced in this way. The metallurgical coke consumption was decreased by as much as 377 pounds (25.3 percent) per ton of pig metal produced. Buckwheat anthracite No.4 was used in this experiment; however, such solids as bituminous coal or coke fines also could be used. The frequency as well as the quantity of solid fuel injected has a direct bearing on furnace performance.

Jan 1, 1960

The price of copper has gone into the tank. So has gold. Environmental regulations are more restrictive. Global warming has world leaders and environmental groups seeking international regulations to keep the planet from heating up - mostly by restricting the use of fossil fuels. And the US Secretary of the Interior wants to make it more costly -prohibitively so for smaller companies - to mine hard rock metals in the United States. By rights, miners should be carrying around a pessimistic attitude about their industry. But miners are an optimistic lot, always believing that things will improve. That optimism was in evidence in Tucson, AZ in early December, when about 620 miners met at the Double- tree Hotel for the Annual Meeting of the Arizona Conference, put on by SME. Attendees listened as a United States congressman commented on the recent tax cut bill, mining regulations and the continuing need for the mining industry to improve its image in the eyes of the general public. Session speakers discussed how improved technology has made their processing operations at Sierrita and Morenci more efficient and cost-effective.

Jan 1, 1998

By Florian Kongoli

"Lime ferrite" slag with limited silica content has proven to be a valuable choice in the modem processes of copper smelting and converting due to several advantages that this slag offers compared to classical silicate slags. Nevertheless the liquidus surface of this slag has been experimentally measured only at low oxygen potentials such as in equilibrium with iron or near it and in air. Although most of the smelting and converting processes that use this slag occur at intermediate oxygen potentials, the liquidus surface of this slag is not known at these conditions and the effect of oxygen potential and silica has not been correctly understood. This has brought some confusion in literature as well as in the industrial practice. In this work the liquidus surface of the calcium ferrite slags has been quantified by the means of a new thermophysicochemical model and a new type of liquidus surface diagrams which are very convenient for any industrial process that uses calcium ferrite slags. These diagrams can be easily used to select the lowest liquidus temperature of calcium ferrite slags at a minimum cost and can help design several fluxing strategies in copper smelting and converting processes. The effect of the oxygen potential and silica is also quantified and important industrially related conclusions are drawn.

Jan 1, 2003

By Florian Kongoli

"Lime ferrite" slag with limited silica content has proven to be a valuable choice in the modem processes of copper smelting and converting due to several advantages that this slag offers compared to classical silicate slags. Nevertheless the liquidus surface of this slag has been experimentally measured only at low oxygen potentials such as in equilibrium with iron or hear it and in air. Although most of the smelting and converting processes that use this slag occur at intermediate oxygen potentials, the liquidus surface of this slag is not known at these conditions and the effect of oxygen potential and silica has not been correctly understood. This has brought some confusion in literature as well as in the industrial practice. In this work the liquidus surface of the calcium ferrite slags has been quantified by the means of a new thermophysicochemical model and a new type of liquidus surface diagrams which are very convenient for any industrial process that uses calcium ferrite slags. These diagrams can be easily used to select the lowest liquidus temperature of calcium ferrite slags at a minimum cost and can help design several fluxing strategies in copper smelting and converting processes. The effect of the oxygen potential and silica is also quantified and important industrially related conclusions are drawn.

Jan 1, 2003

By S. Stutz

Coal, like most other minerals, only exceptionally occurs in a sufficiently pare state to he directly available for general manufacturing purposes. And even where this is the case, the small coal or slack is usually more impure than the lump coal, as the slate, clay, etc., from the roof and bottom of the vein become mixed with it in the handling it undergoes. These impurities often exceed ten or more per cent. in addition to the impurities of the coal itself. The most common impurities of the coal are slate, or shale, clay, and sulphur. The latter occurs in different forms, but moat frequently as bisulphide of iron, or iron pyrites, and as sulphate of lime, or gypum. In both cases the impnrities add greatly to the amount of ash, and where they are present in considerable quantities the raw coal, and still more the coke made from it, is unfit for the manufacture of iron. Coke will coutain on an average at least fifty per cent. more ash and sulphur than the ram coal from which it is made. To the manufacturer of iron every additional per cent. of ash which his coal or coke contains is a source of additional expense, seemingly small, and yet very important in the aggregate. In the blast-furnace, for instance, the ash must be heated up to the melting-point, and, since it is composed largely of refractory substances, the consumption of carbon in melting it will be equal to at least one-half of its weight; that is, a certain part of tile coke is consumed for the melting and fluxing of the ash and is lost. Besides this, it is well enough known to the iron-master that coke containing lees ash makes the &lag or cinder more liquid and less incliner1 to stick to the walls of the furnace. Fuel containing much sulphur produces generally a white iron, poor in carbon, while from the same ore arrd flux, with a pure fuel, a good foundry iron might be obtained. The work of separating slate, sulphur, etd, from the coal has as yet only been successfully accomplished by the washing process. This process depends for its success on the differences in the specific

Jan 1, 1881

By Elmars Ence, Harold Margolin

The Ti-Fe and Ti-Fe-0 systems were re-examined because of the controversy regarding the existence of Ti2Fe, and to consider all available data points to the existence of Ti,Fe. The Ti-Fe-0 system contains two ternary compounds: E, corresponding to Ti2Fe; and y. SEVERAL authors have investigated the constitution of titanium-rich alloys of the Ti-Fe system. The most extensive study of titanium-rich portions of the Ti-Fe system was by Van Thyne, Kessler, and Hansen,' who investigated this system up to 50 pet Fe and used the highest purity materials available for their alloy preparation (iodide titanium was used for alloys up to 20 pet Fe). According to Van Thyne et al., phase relationships in the region of investigation are governed by phases a,ß, and TiFe. No evidence of an intermetallic compound Ti,Fe was found. although earlier. works by Laves and Wallbaum,' and Duwez and Taylor' reported its existence. Rostoker's study on the occurrence of TilX phases" confirmed the findings of Van Thyne et al. Rostoker proposed that the compound Ti Fe found by Duwez does not exist but is actually a ternary compound, Ti1Fe3O, originated by inadvertent oxygen contamination. The partial isothermal section of the ternary Ti-Fe-0 system as reported by Rostoker' seems to confirm this explanation. In the course of phase diagram work conducted at New York University, however, certain irregularities were observed to be associated with ternary systems of the type Ti-Fe-X. The ternary phase 6, observed in the systems Ti-Fe-Mo' and Ti-Fe-V." was found to be structurally identical to the com-pound Ti2Fe as reported by Duwez and Taylor, and to Rostoker's compound Ti1,Fe2O. Since the amount of oxygen possibly present in the Ti-Fe-Mo and Ti-Fe-V systems could not account for the observed amounts of the compound, it appears that the d phase in these systems is not Ti,Fe,O. On the other hand, considering the amounts of the 6 phase, particularly in the Ti-Fe-Mo system, the location of the phase was uncertain. It was felt that the introduction of the Ti2Fe phase would alleviate some of the inconsistencies of the two systems. Because of the uncertainties relating to the phase Ti2Fe, or Ti1Fe2O, it appeared worthwhile to re-examine the Ti-Fe and Ti-Fe-O systems in the vicinity of these compounds with highly sensitive metallographic techniques and with X-ray methods. Experimental Procedure Alloy Preparation—For the study of the binary system four alloys were prepared, containing 26.9 (30 wt pct), 34.0 (37.5 wt pet), 41.2 (45 wt pet), and 56.3 (60 wt pet) atomic pet Fe, and for the ternary Ti-Fe-O system 18 alloys were prepared in the composition range of 1.6 to 16.9 atomic pet 0 and 24.3 to 55.7 atomic pet Fe. The materials used for the Ti-Fe alloys were iodide titanium (99.98 pet Ti, 0.002 pet 0) and Ferro-vac-E iron (99.95 pet Fe, 0.0052 to 0.0072 pet 0). For the Ti-Fe-O study the materials used were sponge titanium containing less than 0.06 pet 0, Ferrovnc-E iron, and Baker's analyzed TiO2. The nominal weight and atomic percentages of the ternary alloys prepared are shown in Table I. Melting—Charges of 10 to 15 g were melted in a nonconsumable arc furnace in argon atmosphere according to the technique described elsewhere.'" Since there was practically no weight loss through the various stages of melting and oxygen losses have not been observed previously, it appeared justifiable to use nominal composition for interpretation of data. Iodide titanium control buttons, of the same mass as the Ti-Fe charges, and melted under the same conditions, were used to check hardness pickup during melting. A hardness increase of 2 to 3 Vhn was found. Heat Treatment—The specimens were annealed in quartz capsules under argon. To avoid contact between the specimen and capsule material all specimens were wrapped in titanium sheet. The annealing times are given in Table 11. The attain-

Jan 1, 1957

By Clarence Zener

THEORETICAL considerations by one of the authors have led1 to the prediction that the dynamic internal friction of annealed metals has a broad maximum at a certain grain size. This prediction they have veri-fied2 for alpha brass. In the present paper the theory is extended to include the precise manner in which the internal friction varies with grain size on either side of the maximum. New experimental data are pre¬sented to test this extended theory. The physical basis for the type of internal friction that is being investi-gated lies in the interplay between stress and temperature. Just as local fluctuations in temperature give rise to local fluctuations in stress, so like-wise fluctuations in stress give rise to fluctuations in temperature. But temperature gradients give rise to necessarily irreversible thermal cur-rents, and hence to internal friction. The theory for this type of internal friction has been developed quantitatively,3 and has been experimentally verified,4,5 for the particularly simple case of the transverse thermal cur-rents accompanying transverse vibrations. Of more fundamental impor-tance are the intercrystalline thermal currents accompanying all types of vibration. The variation in stress across grain boundaries arises from the elastic anisotropy and at least partial random orientation of the individual crystallites. An exact quantitative treatment of the internal friction due to these thermal currents is of course out of the question. However, much information can be obtained from general arguments.1,6 Thus when the frequency of vibration f is low, or when the grain size d is small, adja-cent grains remain nearly in thermal equilibrium, and vibration proceeds isothermally with little internal friction. Again, when the frequency is high, or the grain size large, the heat flow per cycle is small, the vibration proceeds adiabatically with little internal friction. The internal friction will become a maximum in the transition region. The degree of adiabatic-

Jan 1, 1940

By N. L. Parduhn

Populations of Bacillus cereus spores are elevated in soils over four subsurface gold deposits in the western United States. Large deposit-to-background ratios of B. cereus populations were obtained in soil traverses over the Minnesota vein deposit, Empire District, Colorado (maximum 50:1); the Shasta (maximum 3,500:1), and Evening Star maximum 18,000:1) vein deposits, Shasta County, California; and the Hog Ranch disseminated gold deposit (maximum 40,000:1) in Washoe County, Nevada. Small increases in the concentration of toxic metals in the soil may be responsible for the elevated spore populations. The observed elevation of B. cereus spore populations near these gold deposits indicates that the method should be further investigated as a potential exploration tool.

Jan 1, 2013

By A. V. Tarasov

Technology has been developed for production of elemental sulphur from off-gas from autogenous smelting processes based on reduction of sulphur dioxide with natural gas with subsequent treatment of reduced gas containing hydrogen sulfide by the Klaus method. This technology has been applied on a commercial scale at the copper smelter of the Norilsk Mining and Metallurgical Complex for treatment of off-gas from the Vanyukov smelting process (PV). In the course of further improvement of the technology a catalytic version of the process has been developed based on the use of a catalyst at the reduction stage, which permits a decrease in the natural gas requirement by 25% to 30%.

Jan 1, 2006

An appropriate change in Art. I, Sec. 9, of the bylaws was voted by the Board on April 16 whereby, in the case of Student Associates applying for change of status to Junior Member, only two endorsers are needed instead of three, provided one of them is the same member who endorsed his original application for Student Associateship.

Jan 1, 1952

Severe development difficulties were experienced soon after in-seam mining commenced at Appin Colliery in'1962. Thirteen years later no significant pro- gress had been made in overcoming some aspects of this development problem. Some success had been achieved in destressing roadways both in development and pillar extraction. Longwall retreat mining had shown promise of being highly productive but at an extremely high cost in terms of development requirements both in number of roadways and intensity of support in those roadways. No real advance was made in the problem of driving the first heading of a group of headings under conditions of apparently high stress in directions other than the preferred mining directions, although failure of the roof in this heading did seem to give easier work in the subsequent headings driven particularly if they were driven on narrow centres.

Jan 1, 1976

By D. M. S. Bhatia

Five sulfide minerals from the Magiwnt mine, southeast Missouri were analyzed for 31 trace elements in over 300 samples by laser microprobe spectrographic analysis of polished sections. The concentration of several trace elements shows a pattern of progressive variation with depth (space) and variation with different paragenetic stages (time) of each mineral. Factor analysis of the geochemical data shows sympathetic correlation both in space and in time of Bi, Cd, Ge, and Sn in galena and sphalerite, and Ni and Co in sphalerite and marcasite.

Jan 1, 1979

By Jochen Petersen, Harro von Blottnitz

"The landfill disposal of slags is common practice in the metallurgical industry. Chromium may be a minor constituent in many cases. It is present mostly in the form of chromites, which are considered environmentally benign and hence safe for disposal. Wastewaters from metal finishing operations are most commonly treated by reduction and precipitation of dissolved metals, including chromium, by lime addition, and subsequent landfill disposal of the resulting sludge. The metals contained in such sludges are mostly in the form of hydroxides, and as such considered environmentally stable.Thermodynamically, trivalent chromium, which is the predominant form in these waste materials, can be oxidised to the hexavalent form by atmospheric oxygen. Detailed research work on both slags and sludges has shown that a gradual emergence of hexavalent chromium can indeed be observed. The mechanism is governed by close physical contact between chromium oxide (or hydroxide) phases on the one side and calcium oxide (or hydroxide), which is present as flux in slags and residual lime in sludges, on the other. If oxygen can migrate to the points of contact, gradual formation of calcium chromate ensues.Hexavalent chromium is associated with high environmental toxicity, and hence undesirable in landfilled materials. Moisture migrating through landfill deposits can mobilise the highly soluble chromates and thus potentially transport them into natural waterways. Such gradual release from stainless steel and ferrochromium slag deposits has been demonstrated in a column experiment."

Jan 1, 2003

By Yves Fouquet

Recent exploration demonstrates that hydrothermal systems related to upper mantle ultramafic outcrops are common in the modern ocean. Most sites are located on slow spreading ridges with a low magmatic budget. Volcanogenic Massive Sulfide (VMS) deposits, associated with basalt, along the Mid Atlantic Ridge (MAR) are volcanically controlled near the topographic highs at the center of the segments. Three preferential settings are identified for ultramafic sulfide mineralization: 1) Off axis, on rift valley walls, near the amagmatic ends of the segments; 2) Non-transform offsets and 3) Ultramafic dome structures at the ridge transform fault intersection. The upper surface of these domes is often interpreted as a detachment fault. Three processes are considered for driving hydrothermal cells in ultramafic rocks: 1) regional heat flow at the ridge axis 2) Cooling of a deep gabbroic intrusion and 3) exothermic heat produced during serpentinisation. Along the Mid Atlantic Ridge, four types of ultramafic hydrothermal mineralization are observed: 1) High temperature (>350°C) sulfide mineralization related to low pH fluids, (ex. The Logachev field at 14°45? N and the Rainbow field at 36°14 N); 2) Medium temperature carbonate chimneys (<100°C) related to high pH fluids (ex. The Lost City site at 30°N); 3) Low temperature diffuse venting associated with extremely high methane discharge and pervasive alteration and silicification of both volcanic and ultramafic rocks (ex : The Saldanha field at 36°34 N); 4) Stockwork mineralization and quartz veins with sulfides related to gabbroic intrusions within ultramafic rocks (15°N). When compared to mineralization in a basaltic environment, sulfide deposits are enriched in copper, zinc and specific elements related to an ultramafic rock source such as Ni and Co. They are also significantly enriched in gold which, unlike in basaltic environments, has a bimodal occurrence both in low temperature Zn-rich assemblages and in high temperature Cu-rich mineral assemblages. The Cu-Zn-Co-Au deposits along the Mid Atlantic Ridge seem to be more common than on land where few similar VMS deposits are known. We consider that ultramafic VMS deposits on slow spreading ridges constitute a specific marine type of mineralization that is less easily than back arc deposits, incorporated into the continent during obduction processes.

Jan 1, 2004

By N. P. Kripakov

This paper presents a brief overview of current bump mechanics theories and pillar design methodologies, and relates these concepts to experiences at two mines located in a north-central Utah coalfield where different pillar designs were used to control mountain bumps. Experiences gained at the first mine demonstrated the successful implementation of a two-entry, 9.8 m (32 ft)-wide, yield-pillar design. A U.S. Bureau of Mines field study quantified the timing of chain pillar yielding and resulting load transfer from the gateroad. In-mine pillar response, although apparently sensitive to site-specific conditions, compared favorably to estimates derived using two yield-pillar design methods. A second study conducted at another mine located in the same district, but subjected to different geologic conditions, documents the unsuccessful attempts to employ progressively narrower three-entry pillar designs based on successes achieved at the first mine site. This second mine never achieved a true yield-pillar design. Use of pillar widths ranging between 9.1 m (30 ft) and 27.4 m (90 ft) always resulted in violent bumps in the tailgate pillars. The pillars were either too large to yield, or too small to support peak operational loads. Hypothetical gateroad systems were evaluated using both analytical and empirical approaches for configurations comprised of two rows of conventional pillars, and systems incorporating both yield and abutment pillars. Analysis concluded that yield pillars less than 6.1 m (20 ft) wide and abutment pillars ranging between 30.5 m (100 ft) and 39.6 m (130 ft) square would be required to achieve a stable gateroad design. However, results of a field study conducted on a two-entry, 36.6 m (120 ft)-wide abutment pillar concluded that abutment pressures from the first panel overrode the pillar, and that a still larger pillar may be required to preclude bumps in the tailgate during second panel mining. Without the benefit of a demonstrated in-mine success, it is not clear which design would ensure elimination of gateroad bumps.

Jan 1, 1992

By Joshua Brien

DEEP SEABED MINING IN NATIONAL JURISDICTION: KEY CHALLENGES The talk focuses on the key challenges that arise from deep-seabed mineral exploration and development within areas of national jurisdiction, including legal and institutional challenge and options to address these challenges. Joshua Brien has acted for a range of Governments throughout the world, including smallisland States and the developing world. This has included engagement in matters before the International Court of Justice, the Tribunal for the Law of the Sea in contentious and advisory proceedings, including provisional measures applications and prompt release cases.

Jan 1, 2018