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By Hua Hou, Xiaofeng Niu, Wei Liang

"The explicit finite difference (EFD) method is used for calculating the casting temperature field during solidification. Because the time step is limited, the computational efficiency of the EFD method is lower. In order to improve the computational efficiency, a fourth-order in space and second-order in time model based on the equivalent specific heat method and the alternating direction implicit (ADI) method is established. The degree of similarity between the simulation results and the experimental results is analyzed. The results show that the simulation results of this high order mathematical model are close to the experimental results.IntroductionThe 3D heat transfer equation of temperature field during solidification process is as the following: [1-3]."

Jan 1, 2013

By S. K. Kawatra

Many mineral oxide and multi-component oxide (basalt) specimens break down into powders upon expo-sure to sodium vapor at elevated temperatures for extended times. This paper examines several possible mechanisms of oxide breakage by sodium vapor, both experimentally and from a thermodynamic viewpoint. The oxides for which reduction by sodium was thermo-dynamically favorable all exhibited some degree of fragmentation. The oxides which were not favorable for reduction by sodium did not exhibit fragmentation, with the exception of rutile, a titanium oxide. The rutile fragmentation was caused by the reduction of iron that was in solid solution in the rutile crystal structure.

Jan 1, 1995

By Richard Harrison, Frank Lim

"Lifting of slurry from the seabed mining machine to the surface production vessel is a critical element of any deepwater seabed mining system. A Vertical Transport System (VTS) comprises pump(s), riser string, connectors and hang-off assembly as its main components, but it is the pipe material, riser configuration and installation method that often attract the most discussions.This presentation will feature important VTS design work 2H has done over the years for different stakeholders, and highlight the work carried out as a partner to the EU funded Blue Mining Joint Industry Project.The key challenges faced by a deepwater VTS are:??High riser payload??Large deck space for storing riser joints??Long time to deploy and retrieve riser??Uncertain metocean conditions??Vortex induced vibrations??Weld and connector fatigueIncreasing the water depth further sees the longer and increasingly ‘springy’ riser experiencing axial resonance caused by wave induced vessel heave motions being close to the riser resonant period. This can lead to snatch loading and fatigue failure in the riser.The presentation will discuss the above design issues, analysis requirements and provide guidance on pump/riser selection. Solutions to mitigate the resonant response issues will also be proposed.."

Jan 1, 2017

By R. L. Hopkins, H. T. Rall

A continuous method has been developed for preparing thiolacetic acid . Acetic anhydride and hydrogen sulfide are passed concurrently over an amine ion- exchange resin , under 20 - psi pressure . The thiolacetic acid , a product of the reaction , is flashed continuously from the crude reaction mixture and is purified by fractional distillation . The yield of thiolacetic acid is in excess of 80 percent based on the acetic anhydride charged . INTRODUCTION In the synthesis of reference compounds needed in the identification of sulfur compounds in petroleum , thiolacetic acid has become an important reagent because of its use in the synthesis of thiols by addition to appropriate olefins : R - CH = CH₂ + CH3 - COSH R- CH2 - CH2 - S - COCH R - CH2 - CH₂ - SH + CH3COONa NaOH (1 ) The commonly used procedures for its preparation , as described by Clark and Hartman (1 )4 and by Ellingboe (2 ) , are based on the batchwise reaction of acetic anhydride with hydrogen sulfide :

Jan 1, 1964

By D. W. Tuckwiller

Electroplating is a widely utilized but little understood process. The fact that the average person is in contact with dozens of plated items daily without even being aware that they are electroplated is evidence of the success of the process. Although a complete explanation of electrodeposition involves thermodynamics and modern theories of bonding and catalytic reactions, in its simplest form the process conforms to the following description. A metal salt dissolved in water partially dissociates into negatively charged and positively charged ions. In the case of nickel sulfate dissolved in water, for example, a portion of the salt dissociates into positively charged nickel ions and negatively charged sulfate ions. If an electrical potential is applied between two electrodes in this solution, the nickel ions migrate toward the cathode and the sulfate ions toward the anode. The negatively charged cathode has a high concentration of electrons, which combine with the positively charged metal ions to form neutral metal atoms with a stable electron configuration. These insoluble atoms thus form a deposit on the cathode.

Jan 1, 1970

By Enichlmayr E

Lignin grouts are cheap and easy to get. They have some desirable properties, but they aag less used now because environmental pollution is often caused by Cr from the lignochrome component of the grout. Their usefulness was researched in an earlier paper on lignin as a grout from other viewpoints. A non-toxic grout FUL was made composed of furfural, urea and lignin. After initial tests, including tests by spinning regression design, some response equations in which FUL's properties are described were obtained. Optimum formulations have been established by using optimization methods based on response equations. The engineering quality was assured by formulations whose properties were measured in further tests. The mechanical feature of gelling sand was measured by means of triaxial tests. This provides a basis for using FUL grout in-situ. Finally, an in-situ experiment on FUL was completed successfully. The results were that cracks in stratum were filled or blocked, the gelling of FUL had high strength, and low permeability and consolidation were achieved.

Jan 1, 1988

By E. A. Swedenborg, J. S. Ross

Oil-field waters enter into many underground problems with which the petroleum engineer has to deal. Whether the problem is one of infiltration or natural encroachment, it is always desirable to determine the source of the water before commencing repair or remedial work. The usual mechanical tests for determining the source of extraneous water in wells are slow and expensive. An excellent means for the identification of oil-field waters may be afforded by their chemical characteristics when the chemical character of waters from the various sands has been established by careful sampling and analysis cautiously interpreted. In the Salt Creck field, Wyoming, a fairly high degree of efficiency has been attained in the control of field operations by utilizing the information afforded by the analysis. All of the operating companies appreciate this means of identifying waters, with the result that water-sampling has become general practice. Most of the chemical work dealing with Salt Creek waters has been done since the laboratories of the Midwest Refining Co. and the U. S. Geological Survey, were established in the field; the former in 1922, the latter in 1924. A spirit of cooperation has existed between the company and the government personnel by which many of the data for this paper were made available. Sands of the Salt Creek Field The principal sand horizons in the Salt Creek field are the Shannon, First, Second, and Third Wall Creeks, Dakota, Lakota, Sundance and Tensleep. Of these the important oil producers are the First Wall Creek, Second Wall Creek, Lakota and the Sundance. The Third Wall Creek is lenticular and is productive in only a few wells in the southern end of the field. There are also a number of shale wells, but they do not produce water in any appreciable amount. The stratigraphic position of these sands and their relative thicknesses are shown on the condensed composite section of Salt Creek

Jan 1, 1929

By B. Pesic

Northwest Alloys, a wholly owned subsidiary of Alcoa, produces magnesium from dolomite by reduction with ferro silicon and aluminum. This process produces alkaline by-products in quantities that allow their consideration for use as commercial by-products. Two such products are dicalcium silicate slag, Di-Cal, and magnesium oxide condensate, MgO. The alkaline properties of these materials offer acid neutralizing capability comparable to the traditionally used lime, therefore, warranting a study for their use in applications where the neutralization of acidic waters or process solutions is required, such as treatment of mine waters. In this ongoing study, three mine waters (Bunker Hill Mine, Berkeley Pit, and Blackbird Mine) were selected for treatment with Di-Cal and MgO. Lime was used as the background control. The solid precipitates were subsequently contacted with pure water at four different pH conditions for stability testing of prepared metal precipitates (expanded TCLP). It was found that neutralization with Di-Cal results in precipitates which are of equivalent to superior stability than those from lime treatment.

Jan 1, 1999

By Paul C. Schmall, John F. Donohoe, Arthur B. Corwin

In the aftermath of the September 11th attack on the World Trade Center, groundwater control was of immediate concern. Water in?ow from the adjacent Hudson River through the compromised slurry wall ‘bathtub’ surrounding the site, ruptured water and sewer mains, and saturation from fire hoses all contributed to an already critical situation, further hampering the recovery and rehabilitation effort. An extensive pumping and deep well installation program was initiated, focused on reducing the hydrostatic loading to the severely damaged perimeter slurry wall.

Jan 1, 2003

By Zhiqing Zhang, Changyun Chen, Qing Liu, Lin Lin, Zhihong Jia, Guangjie Huang, Lipeng Ding

The effect of interrupted quenching (IQ) treatments on natural aging and bake hardening response of Al-Mg-Si alloy was investigated by hardness measurements, tensile test, differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). The results show that interrupted quenching at 100oC could effectively suppress natural aging and improve bake hardening response. The optimized interrupted quenching treatment is 100oC for 45min, which gives the alloy a relatively low T4 temper strength and higher bake hardening response. The formation of highly dense cluster(2) during the interrupted quenching could be the reason for suppressing the natural aging and accelerating the precipitation of ß? phase during the paint bake treatment. In addition, interrupted quenching at higher temperature (170oC) results in unfavorable properties in both T4 temper and paint bake treatment. The formation of large precipitates is responsible for these undesired effects.

Jan 1, 2015

By Bruce F. Bohor

Silica sand has been mined in Illinois from the St. Peter Sandstone since the turn of the century, especially in the area around Ottawa on the Illinois River in the north-central part of the state. Production of this sand, consumed mainly by the glass and foundry industries but also sought after for many other uses, has grown with the economy, and last year's output in Illinois exceeded 4,000,000 tons. Such an important commodity was given the early attention of the Illinois State Geological Survey, and a very complete report was issued in 1928, authored by J. E. Lamar. The mining and processing of the sand has changed very little during the intervening 40 years, so that much of Lamar's data and descriptions are applicable today. More recently, the stratigraphy of the St. Peter Sandstone in north-central Illinois has become better known from the work of Willman and Payne (1942). The present authors have borrowed generously from Lamar's publication, and we wish to acknowledge the contribution of both of these studies to our work.

Jan 1, 1969

By C. Dinis da Cama

In order to reduce the complexity of mechanisms influencing rock- fragmentation by blasting a simulation approach is proposed, using the capabilities of micro-computer interactive graphics. Situations involving cratering and bench blasting are simulated, and both jointed and intact rocks can be subjected to explosive action, taking into consideration its breakage mechanisms. Size analysis curves relating rock distribution before and after the blasts are determined and compared with field data.

Jan 1, 1984

By Dru Brown

More than 150 Mt (165 million st) of material crashed down at the Bingham Canyon Mine (Rio Tinto/Kennecott Utah Copper) near Salt Lake City, UT on April 10, 2013. The mine, one of the largest openpit mines in the world, ceased operations and evacuated personnel prior to the slide when it was discovered that material was moving at a rate of 5 cm/d (2 in./day). The slide destroyed the mine?s visitor?s center, buried several pieces of large mining equipment and severely hampered production. The Kennecott Utah Copper Corp. immediately began to assess the damage and look for options to reestablish operations. The highly unstable ground ? emphasized by another minor slide in September 2013 ? makes any cleanup efforts extremely dangerous. With terrain too dangerous for human operators, Kennecott was forced to look for alternatives that would help the company work on the treacherous slopes of the landslide while also keeping personnel safe.

Jan 1, 2014

By Edwin Itzig-Heine, Daniel Traylor, Bernard Tarralle, Michael McKenna

This paper discusses the challenges associated with the design and construction of a dual-cell, “figure eight” shaped shaft in saturated, soft ground for the Northeast Interceptor Sewer project in Los Angeles. The shaft will be excavated to a depth of41 m and used to launch two EPB TBMs. The specifications required concrete diaphragm walls, embedded below the shaft invert, and a grout curtain beneath the wall. To control water pressure and basal stability without a grout curtain, wall panels were embedded deeper than required into a stiff, cohesive deposit. Details of wall panel excavation using a Hydrofraise are presented.

Jan 1, 2003

By Harrison R. Cooper

With problems of diminishing ore grades and increasing cost of facilities, the mineral industry is acutely aware of the needs for improving beneficiation processes. Industry and universities are directing intensive technical effort to develop- ment of techniques with potential for using digital computers in automation and process analysis. The main problem of early attempts at on-line computer process control methods was that of economics. Now, with new advances in analysis and modeling making practical application economically important, it appears that minerals beneficiation is on the threshold of a significant jump in operating technology. In reviewing this work, particular note was taken of research and development applied to fundamental processes and the significant areas of effort where operations research techniques are used for process applications leading to the current state-of-the-art. Development of data automation and on-line control methods for process industries is deferred to the next section of this volume. This section deals with computer-facilitated mathematical-modeling development and reviews this work in conjunction with associated prior fundamental research leading to development of the methods. Flotation The 1960 state-of -the -art in flotation modeling was com- piled by Arbiter and Harris in the volume, 50th Anniversary of Froth Flotation, edited by Fuerstenau1. Many workers in the field of flotation initiated their research through flotation models, and this effort has led to use of simulation and operations re search methods employing computer techniques to facilitate advance of this work. The flotation model of Imaizumi and Inoue, published with supporting data in 1962, was expanded in 1968 with the objective of developing a basis for process automation.2,3 The fundamental work of Woodburn and Loveday in 1965 has led to techniques applicable to flotation circuit design optimization.4 This analysis is described in this volume by Woodburn in conjunction with King, Buchalter, and Piper. Niemi5,6 derived models for dynamics of a flotation circuit which were employed in developing a model describing

Jan 1, 1969

No early records of coal in Iowa have been found, although it is very probable that coal along the Mississippi, in the northeastern corner of the state, was seen very early. The United States Census of 1840 showed a production of 400 tons, mined of course in 1839, and the earliest mining, was in Jefferson and Fairfield Counties where the coal was hauled by wagons to shops in the Mississippi River towns years before any railroad was built in the state. In 1840 mines were opened in Van Buren County, near Farmington and Douds, and in Scott County, near Jamestown, all of the product being used locally.' In 1844 D. D. Owen reported seeing mines in the tongue of land between the Rock and Mississippi Rivers, in one of them the coal being 5 to 6 ft. thick, and several other seams south of this locality? In the, late forties a number of small mines were opened in various parts of the state, and in following years in practically every county having coal. The Mystic seam was first opened in 1857 in Appanoose County, since then consistently one of the large producing areas in the state. Consumption was local until the Milwaukee Railroad was built through the county in 1887.1

Jan 1, 1942

X-ray analysis of polycrystalline powder samples has grown beyond its roots in the world of laboratory research and is now regarded as one of the most powerful industrial process-control tools in the field of building materials. This is the key to characterise the element and crystalline phase composition of the material. This is due largely to the development of industrial X-ray analytical systems such as PANalyticalÆs twin solution, which has transformed the advanced analytical techniques born in the laboratory into a robust, workmanlike and easy-to-use tool for todayÆs heavy industries. The increasing use of alternative fuels makes the Bogue method less reliable. Therefore, the real phase quantification by the Rietveld method is the only choice. Additional fine-tuning of the Rietveld method by using alternative methods guarantees the most accurate quantitative results. Moreover, the recent development of ultra high-speed X-ray detectors allows for æon the flyÆ quantitative X-ray diffraction analysis and a truly interactive process and quality control.

Jan 1, 2008

By R. H. Atkinson

With the object of improving the melting, casting, and working of palladium and 95.5 pct Pd-4.5 pct Ru, the effects of different melting atmospheres (reducing, oxidizing, and neutral), crucible linings, and annealing atmospheres have been studied. Some interesting observations are included about the solubility and diffusion of gases in palladium. THE object of the present work was to ascertain the effect of oxidizing, inert, and reducing ambient atmospheres on the melting and casting of palladium and a Pd-Ru alloy commonly used for jewelry. The need for such a study was indicated during World War I1 when jewelers experienced difficulty in their attempts to make small castings of the torch-melted Pd-Ru alloy by the lost-wax process. When the metal was melted under oxidizing conditions similar to those used for platinum, the castings were gassy; on the other hand, if the melting atmosphere was reducing, the castings were hot-torn and brittle. General Experimental Procedure Pure palladium sponge (99.9 pct Pd) and pure ruthenium powder (99.8 pct Ru) were used for making small ingots (50 g) of palladium and 95.5 pct Pd-4.5 pct Ru by induction melting. The coil, 3 in. high by 2 in. ID with 16 turns, was energized by a 20 kva Ajax high frequency converter. The melting crucibles, so-called sand crucibles, which were made of a highly refractory fireclay, were lined with different materials, including proprietary magnesia, alundum, zircon, and zirconia

Jan 1, 1957

By Michael J. Garlich

Steel sheet piling has a long history of use in a variety of permanent and temporary structures. Current engineering practice uses numerous publications and standards for design guidance. U.S. design guidance is fragmented, with numerous inconsistencies between design guides. To improve current U.S. design practice, the North American Steel Sheet Piling Association has initiated a project to produce a design standard that will unify design procedures and provide specification guidance for engineers and users of steel sheet piling. The wide range of uses for sheet pile structures presents a challenge in developing such a standard. Load factors or allowable stresses acceptable for a temporary retaining wall in soil may reasonably vary from those for a river cofferdam or a dockwall located in sea water. However, it is still possible to provide consistent and rational guidance for such varying uses. The standard also can address sheet pile design aspects often neglected in U.S. publications, such as vertical load capacity and resistance to loads applied parallel to the sheeting.

Jan 1, 2008

By L. Escudero-Castejon, S. Sanchez-Segado, A. Jha, Y. Hara, S. Parirenyatwa

Oxidative alkali roasting of chromite is the state-of-the-art process for manufacturing chromium-containing chemicals, which involves dealing with serious environmental problems arising from handling Cr6+-containing wastes generated in this process. In this article a new method for the extraction of Cr2O3 from chromite ores is explained, based on the carbothermic reduction of concentrates in the presence of alkali investigated in the temperature range of 950–1050 °C. Under these conditions, the iron oxides present in the ore body are reduced to metallic iron and the resulting separation of chromium occurs by forming sodium chromite (NaCrO2). The reduced samples are magnetically separated for the recovery of an iron-rich fraction, and a non-magnetic fraction containing NaCrO2, MgO and other impurities. The further treatment of the non-magnetic fraction by leaching yields a Cr2O3-rich product of approximately 85% purity, with remaining alumina, alkali and magnesia. The main advantage of the process is that, under reducing atmosphere and subsequent leaching conditions, the oxidation of Cr3+ to Cr6+ is completely avoided; thereby decreasing the risk of land, air and water pollution.

Mar 1, 2017