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By Frank A. Peters

An evaluation is made of a lime-soda sinter process for extracting alumina from clay. In this process, alumina is extracted by sintering clay with soda ash and limestone and then leaching the sinter with a dilute sodium carbonate solution. The sodium aluminate solution formed during leaching is separated from the residue and treated with lime in autoclaves to remove dissolved silica before alumina trihydrate is precipitated with carbon dioxide. The tri-hydrate is then calcined to a-alumina. Two options, dry grinding and wet grinding, are used in the sintering step. The fixed capital costs for plants producing 1,000 tons of alumina per day are $72 million for the dry grinding option and $66 million for the wet grinding option on a Marshall and Stevens chemical equipment index basis of 240.0. Specific geographic locations of plant and raw material sources are not assigned, but, since this process requires large quantities of both lime-stone and clay, the plant site is considered as variable with relation to the clay mine and limestone quarry. A nomograph is given to find operating costs at various delivered costs of clay and limestone. If the plant is located nearer the limestone quarry so that the delivered cost of clay is $2 per ton and the delivered cost of limestone is $1 per ton, the operating costs are $76.47 and $71.61 per ton of alumina for the dry grinding and wet grinding options, respectively. On the other hand, if the plant is located nearer the clay mine so that the delivered cost of clay is $1 per ton and the delivered cost of limestone is $2 per ton, the operating costs are $80.15 for dry grinding and $75.34 for wet grinding.

Jan 1, 1967

By Iain Sommerville, Hugh Mountford, Dawid D. Smith, Claude Dube, Brett Hixson

JW Aluminum use lean and Six Sigma techniques to continuously improve their target of reliable, repeatable and reproducible (3R) manufacturing. Six Sigma’s second stage gate, known as "Measure" involves identification and qualifying appropriate measuring systems. Metal quality (inclusions) are known in the industry to be an important element in 3R casting. The measurement of inclusions at JW Aluminum historically depended on outside vendors. In order to establish real time inclusion measurement ability within JW Aluminum, inclusion measurement systems in the marketplace were investigated. The qualification of a MetalVision MV20/20 ultrasonic inclusion analyzer are discussed as well as the subsequent application of the system in melting and casting improvement projects.

Jan 1, 2015

By Sadtler, C. B.

IT is generally assumed that in most metals and alloys a given tensile stress produces a given deformation irrespective of the length of time during which the stress is applied. This assumption is justified in most of the important engineering applications of metallic materials; however, in the case of some metals and alloys used or tested at temperatures over or slightly under that at which recrystallization can occur the assumption is not warranted.1 This paper deals with the variations of deformation produced by a constant tensile stress acting for varied lengths of time in the special case of thin aluminum alloy sheet of the duralumin type, which had been subjected to different thermal and mechanical treatments. The material investigated was in the form of a sheet approximately 0.002 in. thick, which had been cold-rolled from a thickness of 0.020 in. It has been found that at a sufficiently high constant tension such material deforms continuously with the elapse of time and that the rate at which this deformation occurs is greatly influenced by the previous thermal and mechanical treatments.

Jan 1, 1927

By C. S. Wageman

Staying competitive in the highly aggressive Powder River Basin is a challenge facing all operators. Any advantage that a mine utilizes to improve productivity and reduce costs could mean the difference in the tight spot coal market. Technological advances in mining equipment and data acquisition at the Eagle Butte Mine in Gillette, Wyoming result in productivity gains and increased maintenance awareness. A new overburden haulage truck fleet with an onboard payload and fault monitoring system interacts via telemetry with the loading shovel and PC's located in production and maintenance offices, enabling staff to monitor production and maintenance on a real-time basis. This paper will describe the system and highlight the benefits realized as a result of its implementation.

Jan 1, 1996

By J. B. Zadra

After the discovery of the rare-earth mineral deposit in the Clark Mountain area near Mountain Pass, San Bernardino County, Calif., two samples wore obtained through the Mining Division of the Bureau of Mines for investigation of possible method of concentration. Three other samples were received later from different locations in the same area. The rare-earth mineral in this ore had been identified by E. T. Schonk as bastnaesite, a fluocarbonate of the rare-earth metals containing cerium, lanthanum, praseodymium, thorium, uranium, etc. Associated with the bastnaesite were barite, silica, and some calcite. The bastnaesite contained a small amount of iron as a coloration and some manganese. Twenty to fifty percent of the weight of the samples studied was bastnaesite, or ten to twenty-five percent total rare-earth oxides; about half was cerium oxide. Apparently, none of this mineral occurred in pure form. Even the highest-grade particles 'wore contaminated by fine, interlocked grains of barite, calcite, and silica; barite contamination predominated, and the barite was interlocked with varying amounts of bastnaesite. While the specific gravities of pure bastnaesite and barite (approximately 5.0 and 4.50 respectively) differ enough to allow separation by gravity, the interlocking of the minerals nullified this difference. Consequently, only a partial separation could be made by gravity concentration. The extremely fine grained texture of most of the ore prevented grinding to a size that would make concentration by flotation practicable; a partial separation of barite by this means was effected.

Jan 1, 1952

By Mikael Calando, Thomas Joussellin

"San Francisco's rapid growth has caused the city to plan for the Transbay Transit Center Project, a visionary transportation and housing project, that will transform downtown San Francisco and the San Francisco Bay Area’s regional transportation system by creating a “Grand Central Station of the West” in the heart of a new transit-friendly neighborhood that will be home to more than 20 new towers rising a high a 1,070 ft. This paper describes the specificities of using advanced diaphragm wall technology, tooling, equipment and installation practices for deep foundation and permanent underground structures. In particular, this paper will emphasize on the urban constraints, geotechnical conditions, and the novel approaches adopted for the construction challenges of the Transbay Transit Center’s Load Bearing Elements, or Barrette PilesPaperThe Transbay Transit Center Project consists of the construction of a new multimodal, five-story Transit Center located in the South of Market neighborhood near the Financial District in San Francisco. The future Transit Center will incorporate nearly 83,000 square feet of retail, a 5.4-acre rooftop park, an extensive public arts program and bus ramps that will connect the Transit Center to a new off-site bus storage facility and the San Francisco–Oakland Bay Bridge. The new facility will accommodate more than 100,000 passengers each weekday and up to 45 million per year. Additionally, the new Transbay Transit Center will replace the since-demolished San Francisco Transbay Terminal, and nearly 20 towers, such as Salesforce Tower, will take advantage of the height increases allowed through the Transit Center District Plan.The approximately $4.5 billion project features a new five-story structure (including two underground stories) and new bus ramps which include a cable-stay bridge. The deep foundations for the pylon of the bridge (Pylon 9) consist of two each 21 ft x 5 ft barrettes (also called Load Bearing Elements in the US) extending more than 180 feet below grade and 10 feet into the bedrock. The barrettes were chosen because of the combination of high loads, significant depth and small footprint. The barrettes are installed using the Diaphragm Wall technology. Nicholson Construction was contracted by Shimmick Construction to install the cable-stay bridge’s foundation elements."

Jan 1, 2016

By J. J. Jonas, G. R. Stewart, N. Pokutylowicz, S. Yue, R. Varano, A. Elwazri

Differing thermal histories in and around a weld can lead to differences in grain size, phase composition and morphology of precipitates; mechanical properties will vary accordingly. Hardness testing gives limited information and the machining and testing of tensile and/or impact specimens that would reveal these variations (which may occur over very small distances) is not practical. Therefore, in this investigation, shear punch testing was applied to measure the variation in the room temperature mechanical properties of a welded pipeline steel.

Jan 1, 2005

By John A. Wolfe

The concepts of sea floor spreading and plate tectonics provide more logical explanations of some geologic processes than were possible a few years ago. I plan to premise my discussion of the regional features of Philippine porphyry copper deposits on this tectonic basis, recognizing that parts of the picture can be explained in other ways, but in the belief that this is the best explanation of the whole. The sequence of events which results in the formation of Porphyry deposits (Figure 1) can be summarized as the result of collision of crustal plates, subduction of the oceanic plate, emplacement of a serpentine ultrabasic diapir, formation of a dioritic magma at depths of 300 to 500 km, rise of the magma to a sub crustal or intra-crustal chamber, eruption of andesitic volcanoes, emplacement of diorite or differentiation of the magma into more acidic products, multiple intrusion of hypabyssal rocks and hydro-

Jan 1, 1973

"A fire design innovation of the concrete lining of the Ohio River Bridges East End Crossing Tunnel has been developed. As a result from a fire suppression and tunnel ventilation system, the project design Heat Release Rate (HRR) was able to be constrained from 300 MW to about 50 MW. With this reduced HRR, concrete lining without passive fire protection may be acceptable, if the tunnel concrete lining will not result in explosive spalling during the designed fire event. Concrete explosive spalling test was proposed to verify this assumption. Since no standard concrete fire explosive spalling testing procedure exists, a project specific testing procedure was developed and fire tests conducted. From fire test results, it is concluded that the proposed tunnel concrete lining, in conjunction with the proposed fire suppressing and ventilation system, will not experience explosive spalling and does not require a passive fire protection system. INTRODUCTION The Ohio River Bridge East End Crossing Tunnel is part of a Public Private Partnership project, which connects transportation network between Louisville, Kentucky and southern Indiana. Located in Louisville, Kentucky, the twin-tube highway tunnel provides northbound and southbound lanes of the Kentucky approach to a new bridge across the Ohio River. Tunnel lengths are approximately 1,675-ft and 1,685 for the northbound tube and the southbound tube, respectively. Connected by two cross-passages, both tubes have a roadway width of 40-ft, for 3-lane traffic, and a vertical clearance of 26.5-ft.The Tunnel was constructed by drill and blast method with shotcrete and rock dowels as initial ground supports. The final tunnel lining consists of 16 inches cast-in-place concrete lining and 20 inches invert slab, with a waterproofing system around the tunnel perimeter. Two (2) tunnel side drains and one (1) invert drain were provided for each tube. This paper describes the rational in assessing fire design requirements of the tunnel final concrete lining, to answer the question whether a passive fire protection system is needed or not."

Jan 1, 2016

By Paul M. Tyler, Carle R. Hayward

DOES it pay to do really good work? Quite likely the practical millman will answer that it does not. The preparation of ores for market is primarily a business enterprise, and by and large the individual operator does not bother his head about squandering our national resources or making easier the job of the smelterman. Having accepted such ore as he may get fro111 the mine, his job is to make the best possible showing with his mill fro111 the standpoint of financial return. His success is measured in dollars and cents, and he has no rightful reason to expect more than scant acknowledgment of any other achievements from the stock- holders of his company who in the last analysis are his employers.

Jan 1, 1936

By E. F. Ferrell

Gold was recovered from scrap electronic 60-40 (tin-lead) solders by drossing with aluminum or zinc at elevated temperatures. The gold, together with other metallic impurities, collected in the dross phase which could then be separated from the molten solder by skimming or filtering. Drossing upgraded the gold concentration by a factor of 10. Further upgrading was achieved by a combination of steps including an oxidation roast and either a combined cyanidation-amalgamation treatment or an aqua regia leach. The gold was then recovered in highly concentrated form from the aqua regia or cyanide solutions by cementation and from the amalgam by volatilization or dissolution of the mercury. The solder was purified by reaction with NaOH to remove dissolved aluminum or with SnCl2 to remove dissolved zinc.

Jan 1, 1976

By C. R. Tang

Due to the current lack of sufficient occupational hazards supervisory staff in China, an occupational hazards supervision regulatory framework is proposed, based on the cloud. Data on respirable dust, noise, heat, toxic and hazardous substances and protection facilities are uploaded to private cloud computing data and service centers to build an occupational hazards supervision system. This system promotes occupational hazards governance. Complex reports are generated. Through the establishment of an occupational hazard supervision data threshold, the dynamic regulation of occupational hazards is accomplished. The main characteristics of this approach are low cost, ease of expansion and maintenance, and strong performance.

Aug 1, 2013

By John E. Latz

QUICKSAND far below the surface, stopped two attempts by the Potash Co. of America to sink a third shaft to a potash bed that lies 1000 ft below the southern New Mexico desert. Virtually all methods of grouting were employed in the two failures without any indication of consolidation of the flowing sand. Sinking the South Shaft at the Carlsbad potash mine seemed an almost insurmountable task, until freezing was employed as a final resort. This process that proved to be the answer may be defined as "the sinking of a shaft by freezing, consists of the formation, in the water-bearing strata, of a large block of frozen ground in which it is possible to sink a shaft without danger of an influx of water, providing the ice-wall between the water outside and the shaft itself is strong enough to resist the hydrostatic pressure." Freezing Method Used Extensively in Europe Successful frozen ground shaft sinking projects had been completed in Europe, and Russel G. Haworth, resident manager of the Potash Co. of America, went abroad in search of the know-how needed for the New Mexico undertaking. The freezing process, with a history of two failures at the time, was first successfully employed by Poetsch in 1885 at the Houssu Collieries near Haine St. Pierre, Belgium. Poetsch contracted to sink the remaining 64 ft of an uncompleted shaft through water laden strata from a depth of 190 ft to a depth of 254 ft. This work was in progress until 1887. The freezing and sinking consumed more than two years. As a result of early failures, the process was not favorably received until soon after the turn of the century. The accurate prediction of success in a given application was made possible by the concerted effort and study of a group of European engineers. Means of accurate deviation measurement and control were devised, the nature and properties of frozen water laden soil (the ice wall) were investigated, a thorough and rational basis of refrigeration load calculation developed, and concurrently the efficiency and dependability of refrigeration machinery was greatly advanced. Numerous shafts in Germany, Belgium, France, and England today testify to the reliability and economical surety of the freezing method. Applied to the South Shaft, which is circular in cross-section and 15-ft diam, the freezing method consisted of drilling holes 350-ft deep, through the water bearing strata into impervious ground-the freeze hole pattern being concentric with the shaft and 31-ft diam. The holes were cased with pipe closed on the bottom end. Smaller tubes were placed inside these casings and connected to a header supplying chilled brine from a refrigeration plant. The brine descended in the tubing to the bottom of the hole and ascended through the annular space between the two pipes to the top of the casing; flowed into the return header and back to the refrigeration plant. Under these conditions, each of the freeze hole casings became surrounded by a cylinder of ice

Jan 1, 1952

By H. Y. Sohn

"The nonferrous production industry has gone through a remarkable transformation in recent years in terms of developing and adopting new technologies. Technology innovations have largely been driven by the need for greatly improved environmental protection in addition to increased productivity. One of the most notable aspects of the new technologies is their ability to reduce the emission of sulfur and other pollutants to extremely low levels.The current industry trends towards more environmentally friendly technologies are bringing about additional benefits of developing more efficient, technically advanced, and continuous processes in closed reactor vessels. Key aspects of these modem trends include the use of increased oxygen enrichment in the process gas, better process control, reduced manpower requirements, and plant operations with more skilled personnel.Computer simulation and modeling of complex processes have become more reliable, realistic, and thus increasingly useful in metal production. Some of the notable examples are reviewed.Finally, the need and advantages for value-added production in the nonferrous industry are discussed.I. IntroductionMost recently commissioned technologies for nonferrous metals production have been developed largely in response to environmental concerns. One of the most remarkable improvements made by the nonferrous industry in the last decade has been the rapid increase in sulfur capture. Before the start of the last decade, 90% capture of sulfur was considered good. Since then, strict emission regulations have become the norm in advanced societies, although smelters in many parts of the world still operate with limited pollution control. Other emissions and discharges have also been substantially reduced, resulting in much improved working conditions and worker hygiene in addition to the overall environmental protection. The development of the more environmentally friendly technologies has accompanied other advantageous advances made in the nonferrous industry, i.e., the trend towards more gas-tight, continuous processes and larger plants. This has increased the competitive edge enjoyed by the industry in the industrial countries, offsetting the higher costs of labor and pollution abatement that they have to overcome in those countries. Experience has shown that clean technology often leads to a profitable business, because its adoption forces the concomitant advancement of related technologies in addition to the avoidance of penalties imposed by the public on pollution-prone industries. Needless to say, there are other driving forces for new technologies such as reduction of operating and capital costs, improved product quality, and energy considerations in terms of reduced consumption and utilization of readily available sources."

Jan 1, 2000

By JAMES GAYLE

(Presented at the Washington meeting, May 3, 1905, and simultaneously sent to the Iron and Steel Institute, for presentation at the meeting of that Society in London, May 11, 1905.) IT is to be regretted that the data respecting the use of dry-air blast, which was presented to the Iron and Steel Institute at its meeting in the United States, in October, 1904, should. have been restricted to the period from August 25th to September 9th inclusive, and from September 17th to 30th inclusive. In order to present the paper at all it was found necessary to limit the record of operations to the period above stated. In the discussion of the paper it would appear from the conclusions of some participating therein, that they have been placed at some disadvantage in considering the economies obtained through the use of dry-air blast, by reason of the data covering such a short period. It is the purpose of this communication to present in detail the record of operations of the Isabella Furnaces from November, 1904, to March, 1905, inclusive, as shown by the furnace-records. The month of October, 1904, is not included, as the furnace using dry-air blast was stopped several times for repairs, and while the record was a very good one considering these interruptions, yet it was not a continuous one. The record for Furnace No. 1 using dry-air blast, and the comparison with Furnace No. 3 using natural air for the month of November, 1904, is set forth in Table I. By a reference to my former paper it will be noted that the month of November is the beginning in this country of the winter period, when the atmosphere decreases rapidly in humidity. The month of October being the transition month in the autumn and April in the spring, and furnaces using natural air approach more closely, from November on, to the conditions obtained by the use of dry-air blast. The data given in

Jul 1, 1905

By M. Kunst

The creep behavior of three AJ62 alloys was investigated in a wide range of stresses and temperatures. Multi-level tensile creep tests revealed a distinct primary creep stage and a high stress exponent up to a value of 10. The threshold stress concept which is commonly used in combination with high stress exponents was utilized in the analysis of creep behaviour. This resulted in an effective stress exponent for the AJ alloys indi¬cating dislocation climb as the dominating creep mechanism. In addition, microstructural observations of the lamellar eutectic and of the a-Mg-matrix were carried out using opti¬cal microscopy, SEM and TEM. The creep properties of the alloys are discussed in the context of microstructural parameters such as phase volume-fraction, stability and solute supersaturation.

Jan 1, 2006

By G. S. Coe, G. F. Bolling

The columnar-to-equiaxed transition (CET) has often been studied as a function of concentration, C, temperature gradient in the melt, G, and rate of solidification, R. Although it may not be immediately obvious it is sure that the CET, expressed as some ratio G/R necessary to suppress equiaxed nucleation for a given C,' cannot be a single-valued function of C. This restriction which is ignored in theoretical presentations is most trivially illustrated by the following simple reasoning. An ordinary casting is an unconstrained system where the thermal conditions change continuously with progressive solidification, and thus where the ratio G/R decreases from the outset. A CET occurring early in a casting (much equiaxed material) must then mean a higher value of G/R at transition, in comparison with the late CET which implies a more columnar ingot. Therefore, when we choose to experiment under constant superheat for all alloys across the simplest binary, and we find an inversion in the amount of equiaxed material, we shall find two values of C satisfying the G/R condition. However, in addition to this simple instance, the early experiments of ~orthcott' seem to show that the amount of equiaxed material in cast ingots may be a multivalued function of composition in a given binary system. In the present investigation, the CET has been examined in Pb-Sb, Pb-Ag, Pb-Sn, and Sn-Pb under several types of casting conditions. First, we have used the "bidirectional" ingot section Simulation;~ and we have used .'i~z situ" ingot solidification where a hot mold already filled with liquid is chilled so that there is no disturbance provoked by pouring. Differences in method are trivial to our purpose except for the fact that certain variations are more simply observed by one technique than by the other. Second, we have varied the mode of superheating from the simple extreme of casting all alloys from the same temperature regardless of composition to the careful casting at a standard superheat, calculated with respect to the alloy liquidus. Third, we have made provisions for decanting and interface observation, so that some "castings" were not completed. The results obtained with Pb-Sb are exemplary; some of these are shown in Fig. 1 along with explanatory captions. At 9 to 10 at. pct Sb, and thus above the solid-solubility limit Cs = 5.8 at. pct Sb and yet below the eutectic concentration Ceu = 17.5 at. pct Sb, there is a persistent anomaly in all the variations. Measurement was easy enough and standard enough so that we may forgo discussion of either method or possible error, in view of the forceful self-consistency shown by experiment. Solute distributions were measured along the bidirectional ingots in order to determine if a solute buildup had occurred at the CET. No anomalous changes in concentration were observed along the bars at either side of the solute anomaly of 10 at. pct Sb. The microstructures of the ingots were also examined across the range of composition investigated. At concentrations less than 9 at. pct Sb the micro- and macrostructures were typical of the cellular-dendritic growth usually reported for the columnar zone. Above the anomaly, both the columnar grain size and the amount of primary phase decreased. This microstruc-tural observation can be correlated with observations made of decanted interfaces. Below 9 at. pct Sb, the interface reveals the "normal" columnar dendritic structure; however above the anomalous concentration range, preferential growth of certain dendrites appears to form a "super dendrite" pattern. In Fig. 2 a microstructural view of the etched '(super dendrites'' shows their constitution both in terms of relative phase proportion and in terms of the ordinary smaller dendrites.

Jan 1, 1969

By J. F. Magee

THERE is nothing new about drag-line dredging for placer gold. The use of the separate unit for excavating preceded the large barge with bucket-line excavator mounted upon it, which has developed to a high state of perfection through use in every part of the world. But at present there is a vogue for a small, inexpensive plant to work economically the shallower gold gravel deposits that the bucket-line dredges do not work. The dragline dredge consists of the drag-line excavator, on caterpillar mounting on the edge of the dredging pond, which feeds the gravel to the washing plant, mounted on a floating barge in the pond. There have been more than twenty-five such plants built and operated in central and northern California and an unknown number in other States. There have been variations in details of design but the essentials are similar in all. I wish to describe the operation of a typical drag-line dredging plant, that of the Wyandotte Gold Dredging Company on the Farnan Ranch in the Oroville district. This organization of six active partners built their first plant on Wyandotte creek in the autumn of 1933. The operation was successful due to wise management, which was based upon good plant design and proper principles of operation. The partners elected one of their number, H. F. England, as manager with full control and responsibility. This plant and operation furnished the pattern for many subsequent ones.

Jan 1, 1937

By Jr. Raleigh

In a cooperative agreement between the U.S. Bureau of Mines and the U.S. Department of Energy, laboratory column-flotation tests were conducted to evaluate fluorosurfactants as selective fine coal flotation collectors. A Middle Kittaning seam coal responded to flotation with both anionic and nonionic fluorosurfactants. These fluorosurfactants were no more selective than MIBC alone. However, for increasing coal yields, nonionic fluorosurfactant systems did not increase total sulfur and ash contents as sharply as MIBC systems. Flotation selectivity also improved slightly when a combined anionic fluorosurfactant-MIBC system was used in acidic pulps (pH < 3.6). While the fluorosurfactants examined will not likely have direct application in current coal flotation practice, other fluorosurfactant systems could eventually prove beneficial for floating fine coals.

Jan 1, 1990

By J Hartnett, B Tarrant, A Rayner, D O’Toole, P Davies

Since 2009, the Northern Territory and Australian governments have been working under a national partnership arrangement to inform a rehabilitation plan for the former Rum Jungle uranium mine. Part of the rehabilitation strategy is to backfill a flooded former pit (Pit), which extends down to 100m below the current pit lake surface and was historically partially backfilled with uranium tailings. It is proposed to utilise the remaining pit volume below water level to sub-aqueously store Potentially Acid Forming (PAF-I) waste rock which currently occupies large stockpiles across the site. The rehabilitation design and planning process undertaken to develop a strategy commensurate to project objectives and construction constraints involved the establishment of key constraints derived from the analysis of historic data sources and preliminary design efforts. Tabled strategies were balanced against dependent project tasks and project objectives, especially surrounding minimising disturbance of highly contaminated materials within the Pit. Ideas were developed in conjunction with industry input and review of case histories to develop a remediation solution that is constructible within the project timeframe and constraints.

Jul 1, 2021