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By A. V. Bradshaw, R. I. L. Guthrie

The behavior of large bubbles in the size range 4 to 25 cm3, rising through molten silver, has been studied. It was found that rising velocities were equivalent to those in aqueous systems of low viscosity. Mass transfer coefficients for oxygen bubbles dissolving in silver were found to be 0.036 ± 0.007 cm sec-1, being close to those predicted for transfer through the front surface of the spherical cap bubble only. It is suggested that the surface active nature of oxygen in silver could account for the relatively low coefficients obtained. MANY metallurgical processes involve interactions between gas bubbles and liquids. Examples include the removal of carbon monoxide in Open Hearth Steelmak-ing, the removal of sulfur by blowing air through copper matte during converting, and the removal of hydrogen from steel during vacuum degassing or inert gas flushing. The steps involved in such refining processes include; transport of the dissolved species to the bubble interface, adsorption and chemical reaction of the species at the interface, desorption of product molecules from the interface, and transport of product gas into the bulk gas phase of the bubble. It has been concluded1 that all the interfacial steps involved proceed so rapidly at steelmaking temperatures that transport of the solutes, present in the metal, become the important rate controlling factors provided nucleation phenomena are not restrictive. The O-Ag system was chosen for the investigation into gas bubble-molten metal interactions due to the relatively high solubility of oxygen that enables rates of oxygen transfer to be measured from changes in bubble volume. Other advantages of this system include the absence of a stable oxide phase at an oxygen pressure of 1 atm and the relatively low melting point of the metal which permits the use of a metallic container, providing that it is resistant to oxidation. In those metallurgical processes where bubbles have an important influence, bubble volumes are usually greater than 5 cm3. For this reason the present study relates specifically to single large bubbles of oxygen rising in silver. These bubbles adopt the characteristic spherical cap shape similar to that shown in Fig. 1 for a 30 cc bubble rising in water. After an initial investigation to determine the velocities of inert (nitrogen) bubbles rising in molten silver, experiments were carried out with oxygen and the rates of mass transfer between the oxygen bubbles and the silver were measured. EXPERIMENTAL Apparatus. The apparatus, Fig. 2, for containing molten silver, was constructed from "Nimonic 75" Alloy (75 pet Ni, 20 pet Cr, 5 pet Fe, Mn) and provided for the release of single bubbles from an hemispherical cup, situated at the bottom of the column. The cup was turned by translating the rotation of the drive shaft through 90 deg. This was accomplished by the use of a bevelled gear system, and a smooth drive was provided by the lubricating action of the silver on the gears. Since reliable high temperature seals at 1000°C were found to be impracticable, the filling and drive shaft tubes were extended outside the 3.5 kw resistance wire tube furnace, where connections were made using easily accessible O-ring seals. The apparatus remained gas tight to the atmosphere at pressure differentials far in excess of those used. The filling tube was connected via a small bore tube to the differential pressure transducer. Gas could be bubbled into the inverted cup from two i-in. tubes which passed down the inside of the column to preheat the gas. The temperature of the silver was maintained at 1020°C during all experiments. Measurement of Bubble Volume. In order to calculate mass transfer rates, it was necessary to obtain a continuous record of the bubble's volume during its passage through the column of molten silver. The method adopted for measuring the bubble volume involved closing off the top gas space to the atmosphere prior to each experiment, and recording the variation in gage pressure of this space during the formation and rise of the bubble. Since any change in bubble volume results in an equal change in top space volume, Boyles Gas Law may be applied (for isothermal con-

Jan 1, 1970

By C. Ortuglio

The effect of cracking by increasing the free space above the charge on the composition and yields of the volatile products from carbonization of Pittsburgh-bed coal and one industrially used blend from Eastern United States and one from Western United States was investigated with the BM-AGA carbonization apparatus. Increasing the free space above the charge from 1 inch to 3 inches, to 6 inches, and to 9 inches resulted in lower tar yields and increased gas and light oil yields. Anthracene and naphthalene yields were increased; quinoline and benzene insoluble fractions of both the tar and pitch increased considerably with increased free space, although the carbon content of the tars and pitches increased only slightly. Increased cracking, occasioned by the increase in free space, resulted in a decrease in the yields of tar acids, tar bases, neutral oils, olefins, aromatics, and paraffins and naphthenes. Gas composition was relatively constant; hydrogen and methane tended to increase and ethane decrease. Results of the investigation are being used to design a unit to upgrade the volatile products of carbonization by cracking the hot products as they leave the carbonization chamber.

Jan 1, 1970

By S. N. Monteiro, C. M. F. Vieira, A. P. N. M. de Sa, J. P. D. Vitorino

"This work has as its objective to characterize an ash waste and to evaluate its incorporation into a clay to produce bricks and roofing tiles. The waste is a type of fly-ash resulting from the incineration of a selected part of urban garbage, which is basically constituted of organic matter and plastics. The waste was submitted to mineralogical and chemical characterization. Compositions were prepared with incorporation of the waste in amounts of up to 20wt.% into athe clay. Rectangular specimens were prepared by extrusion and fired in a laboratory furnace at 900°C. The physical and mechanical properties evaluated were: linear shrinkage, water absorption and flexural rupture strength. The results showed that the waste is predominantly composed of quartz and calcium compounds. The incorporation of the ash was deleterious to the evaluated properties of the clay. It is suggested that the incorporation should be made in amounts below 5wt. % to avoid deleterious effect in the mechanical strength and water absorption of the clayey ceramic.IntroductionThe world attention has turned to a subject of great concern today, the production and disposal of large amounts of industrial wastes as well as wastes of various sources. When deposed in an unsuitable place, these wastes can cause considerable harm to human health and to the environment. Our planet suffers with air pollution, groundwater and soil contamination as well as silting of rivers and lakes with the growing amounts of our society wastes.The recycling of waste materials is of great interest to the industries, mainly due to the environmental agencies legislation. One of the practices for correct disposal of these wastes being investigated is to incorporate into red ceramics, such as bricks and roofing tiles. The natural variability of the characteristics of the clays associated with the relatively simple processing techniques and also the low performance required for the products allow the presence of relatively high levels of impurities in clayey ceramics."

Jan 1, 2011

By J. Cui, Z. Meng, W. Zhao

"The decomposition of rare earth concentrates containing bastnasite and monazite by alkali solutions has been investigated. A slurry of the rare earth concentrate and the alkali solutions was calcined at different temperatures. The impacts of calcination temperature on the decomposition of rare earth minerals, the oxidation of cerium, the deportment of fluorine and phosphorous, and the adaptability of the method to the different grades of rare earth concentrate were all studied. A possible technique for comprehensive recovery is proposed in which the chemical elements such as rare earth, fluorine, phosphorus, calcium, iron and thorium could be recycled or recovered. INTRODUCTIONThe liquid alkali decomposition method is an important technique for the decomposition of mixed rare earth concentrates. The technique is relatively clean compared with the sulfuric acid roasting method. However, its operation is intermittent rather than continuous. The two-step solid-liquid reaction and the subsequent water washing make it not very suitable for mass production and application. An important reason for the disadvantage is that an additional process of ""calcium removal by acid leaching"" is needed for the technique. The content of calcium in Baotou rare earth concentrates is usually 6-12%. The requirement of the current technique is that the content of calcium should be reduced to about 0.2% after the calcium removal process. Otherwise, the decomposition and leaching of rare earth will be affected. Therefore, calcium removal by acid leaching is a necessity before the alkali decomposition process is carried out. Research on different alkali decomposition techniques has been conducted with prior calcium removal by acid leaching (Xu, 1995; Yu, 1993; Han, Li, Chang, Liu & Xu, 1985). There have been some investigations of direct decomposition of the bastnasite (Feng, Pan & Li, 1998; Zhao, Zhang, Yang & Liu, 2002)and monazite (Sun, Li, Li, Su, Zhao & Liu, 1998; Zhou, 2005) by alkali-liquid, however, all studies were carried out in solid-liquid reaction system, and continuous calcination studies have not been reported.This paper investigates the process of direct decomposition of Baotou rare earth concentrates by continuous calcination with concentrated alkali. Using the rotary tubular electric furnace, the mixture of rare earth concentrate and concentrated alkali solution were decomposed continuously. Satisfactory decomposition results were achieved. A method for clean processing and comprehensive resource recovery from Baotou rare earth concentrates is proposed."

Jan 1, 2012

Formation of either sodium jarosite or lead jarosite from concentrated chloride solutions containing small concentrations of sulphate has been demonstrated. Sodium jarosite is precipitated at 95-100°C from FeC13-FeCI2-NaCI-PbCI2 solutions to which was added Na2SO4 or Li2SO4 in amounts greater than 0.05 M. In the absence of alkali metal ions capable of forming jarosites, lead jarosite was precipitated from either FeCI3-PbCI2 or FeCI3-FeCI2-LiCI-PbCI2 solutions to which had been added small amounts of sulphate. Many of the factors affecting jarosite precipitation from chloride solution have been elucidated, and the most critical were sulphate concentration and initial pH. Concentrations of HCI in excess of O. I M essentially suppressed the production of jarosite in chloride media. Alkali jarosite, precipitated in the presence of dissolved lead, incorporates a small amount of this metal into the alkali jarosite lattice. Small but significant amounts of copper can also be incorporated into alkali jarosite and the amount is further increased in the presence of lead. Other divalent base metals such as Zn, Cd or Ni are not significantly precipitated. Sulphate control in either FeCI3 or FeCl3-NaCI leaching systems could likely be maintained by jarosite precipitation provided that the acid concentration of the solution was low.

Jan 1, 1981

By G. Biles

The Eskay Creek Mine, a high-grade gold and silver underground mine in northwestern British Columbia started operations in late 1994. For the first three years of operation, ore was crushed to minus 2 inch; blended to satisfy smelter terms and direct shipped to smelters in Japan and Canada. Before commencing the above operations, preliminary evaluations had indicated that an extremely complex metallurgical facility, requiring a large capital investment, would be required to recover the precious and other economic metals. Subsequently markets for raw ore were identified and underground mining and ore transportation operations, at a nominal production rate of 300 tonnes per day, were commenced. Exploration diamond drilling in 1995 and 1996 discovered additional lower grade mineralized zones, which are less economic or uneconomic as direct shipping ore. Testwork demonstrated that these lower grade zones could be upgraded to marketable concentrates in a simple flotation mill. The mill was built in 1997 and has been in operation since late 1997. The mining rate now has increased to 400 tonnes per day including 250 tonnes per day of the direct shipping ore and ISO tonnes per day of the mill ore. Prime Resources Group Inc. wholly owns the Eskay Creek Mine. Homestake Canada Inc. owns 50.6% of Prime's shares and manages and operates the mine on Prime's behalf. This paper discusses the mining and milling operations as well as ore shipment and smelter contracts' administration.

Jan 1, 1999

During the past decade, the miner-al industries have been faced with an increasing shortage of engineers. The point has now been reached where the shortage may be termed critical. This shortage may be attributed directly to declining enrollment in the mineral science programs offered by the universities on this continent. Although the reasons for declining enrollment are undoubtedly many, two major hypotheses may be postulated. The first is that high-school graduates are either unaware of the mineral industries and the opportunities in them or that they are aware of them but have somehow obtained a false image of their true nature. The second is that they are aware of the true nature of these industries and the opportunities they offer but find them exceedingly unattractive. The problem of dwindling enrollments has, in recent years, been subjected to a concerted attack by the industries and professions concerned. However, their efforts to date have been based essentially on the first hypothesis. Sufficient results are now available to suggest that either the methods of attack are inappropriate

Jan 1, 1965

By R Bradford, W Gift-Agbey, T Vorster, P Morgan, E Grobler

The Asanko Gold Mine in Ghana started processing ore from the Nkran pit in January 2016 at a production nameplate of 3 Mt/a. The flowsheet is a conventional SAG, ball mill and pebble crusher (SABC) with gravity-gold and carbon-in-leach (CIL) recovery. The nameplate production was comfortably achieved within 3 months, so much so, that it was clear the SABC circuit was capable of processing more than the downstream section of the plant. Consequently, a program of de-bottlenecking was initiated to rectify volumetric capacity constraints. This program was later referred to as ‘Project 5 Million’ (t/a) or P5M. Having completed the de-bottlenecking exercise, it became evident that the SABC circuit could not reach 5 Mt/a solely on hard rock from Nkran. The new challenge was therefore to increase the capacity of the milling circuit through a focused comminution initiative that would address the following: geometallurgical treatment plan; upfront fragmentation requirements; installation of feed and mill monitoring equipment; and integration of a knowledge-based control strategy. This paper takes the reader through the various measures implemented to increase the milling rates and to create a stable/ sustainable control philosophy. As a result of the implementation of advanced mill performance monitoring technology (MillSlicer) and the collaboration between a team of experts in comminution, control and operations, the Asanko Gold Mine process plant feed tonnage has successfully increased from 3 Mt/a to 5 Mt/a.CITATION:Bradford, R, Gift-Agbey, W, Grobler, E, Morgan, P and Vorster, T, 2018. Optimisation of Asanko’s Obotan SABC circuit to achieve ‘Project 5 Million’, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 477–484 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By C. G. Anderson

Historically, the treatment of orebodies for recovery of valuable constituents presents many processing challenges. In a time of heightened environmental awareness, the constraints placed on processing complex orebodies are becoming more and more pronounced. As such, established technologies are limited in their ability to fill the needs of these emerging sources of raw materials. A prime example of this is in processing PGMs from primary sources. Normally, this type of material is found in a nickel-copper-iron sulfide matrix. Typically, these materials are processed by established pyrometallurgical means. However, other options should be considered. Hydrometallurgical processes are available which offer advantages over pyrometallurgical methods. One of these is the nitrogen species catalyzed sulfuric acid pressure leach used industrially by Sunshine Mining and Refining Company. In 1990, laboratory work was undertaken in cooperation with Stillwater Mining Company to test PGM matte materials from the Columbus, Montana smelter. The initial results were very positive, and they led to a design to recover PGMs in a high grade residue and to recover nickel and copper as valuable products. Handling the iron and other wastes in an environmentally safe manner was also successfully investigated.

Jan 1, 1995

By John Wulff, J. H. Hollomon

SERVICE failures in brass condenser tubes are often due to corrosion. One of the commonest types of corrosion reveals a surface structure of redeposited copper.1 The study of the effect of alloy addition agents in preventing this kind of corrosion has received impetus from the extensive publication of Bengough and May.2 The mechanism of such inhibition gauged from immersion corrosion,' cell corrosion,' and electrolytic potential' measurements is controversial. This controversy may be attributed in part to a lack of definite knowledge5 of the actual nature of the initial films formed in corrosion experiments. In our own corrosion work on copper and 70-30 brass this lack became apparent and necessitated an examination of surface films by X-ray and electron diffraction methods. The present paper is but an introduction to the subject of inhibition and reports the structure of films formed in active corrodents. EXPERIMENTAL PROCEDURE The arsenical coppers and brasses used in this investigation were made by one of the writers* in the plant of the Revere Copper and Brass Co. at Rome, N. Y. Standard commercial melting practice was followed. O.F.H.C. copper and electrolytic zinc were used and all arsenic additions were made by additions of a master copper alloy. The final analyses are given in Table I. Likewise, the extrusion, cold-rolling, and intermediate anneals employed followed standard usage. Final heat-treatments were given to all materials to produce a similar grain size (0.035 to 0.045 mm. for brass and 0.015 to 0.025 for [ ] copper) for the alloys containing various percentages of arsenic. Samples ¼ by ½ by ¼ in. were cut from sheet material resurfaced and finished with 0000 metallographic papers. The surfaces were all degreased in alcohol and benzine before immersion. After immersion in the corrodent, they were washed gently in tap water, dipped first in alcohol and then in pure benzine and allowed to dry in the diffraction apparatus. The reflection electron diffraction apparatus used has been described by Burwell

Jan 1, 1941

By Albert F. Duzy

Recently there have been some problems associated with hot coal in shipments from the USA to overseas markets. This paper will serve several functions. First, a brief review is presented, together with a selective bibliography. Second, a thorough discussion of coal oxidation is covered. Third, potential effects of storage are presented and, lastly, methods are suggested for the safe storage and bulk transfer of coal. The scope includes coal storage for power plants.

Jan 1, 1983

By J. R. Tonry

In the grinding of dry non-metallic materials such as rocks, ores, gypsum, lime, and cement clinker, it is recognized that only a relatively small portion of the energy is utilized for actual size reduction, and the major portion of the energy used is converted into heat. As a result, heat is generated inside grinding mills imparting to the ground product a higher temperature than that of the mill feed. In some cases, as for instance in grinding cement clinker and gypsum into finished cement, it may be desirable to keep this temperature increase within certain limits, to avoid any change in the properties of the product and, because consumers may specify a maximum temperature of the finished product for reasons associated, with the tulimate use of the cement. The actual proportions of heat and useful work are somewhat indefinite. Some tests have indicated that nearly all the energy is converted into heat, and. other investigators have found that they could account for "everything except the noise." Investigations sponsored by the American Institute of Mining and Metallurgical Engineers, and carried out with an adiabatic calorimeter, indicated that a surprisingly high 19 percent of the energy might actually be used for size reduc¬tion. However, for the purpose of the following discussion it will be assumed that: (Fig. 1) 10% is lost in motor and gears 10% is lost by radiation and convection from the mill body 10% is used for size reduction, and. that 70% of the energy input leaves the mill as heat in the ground. product. A typical example (Fig. 2) would be a 7x22-ft tube mill operating in open circuit, driven by a 400 hp motor, charged with 77,000 lb of grinding media and producing 70 bbl or 26,300 lb of cement per hour. Reducing this cement from a clinker size of 96 percent passing a No. 16 mesh sieve to a specific surface of 3,230 sq cm per gm (Blaine) will increase the temperature of the cement approximately 143F above the temperature of the feed, as explained later. If the tempera¬ture of the clinker therefore is 125F, the finished cement will be 268F, which in some cases may be too hot. : When cement temperatures approach a range during grinding where dehydration of the gypsum becomes a problem, a logical consideration would be some means of reducing the temperature before it attains the range conducive to gypsum dehydration. Regardless of the varying degrees of heat generated within the mill or mills during grindingto various finenesses, consideration of the maximum safe limit for any type of cement being ground, which may vary fromplant to plant, govern in refining the mill circuit to obtain a safe temperature range. All plants are not necessarily required to do the same cooling job, and may or may not use cement coolers following the grinding circuit. (Not discussed in this paper). In the past, various means have been employed for controlling this temperature increase, Such means have included water cooling of the outside of the mill shell; equipping the shell with cooling fins; injection of moisture inside the mill; ventilation through the mill; and., in cases of closed-circuit grinding, drawing cooling air through the classifier; the purpose in all such cases being to remove heat from the grinding system.

Jan 1, 1958

By Nikolaos Petropoulos, Changping Yi, Daniel Johansson, Håkan Schunnesson

The effect of jointing on fragmentation by blasting was investigated experimentally and numerically. Firstly the experimental results were presented. Then the numerical modelling based on the experiments was performed. The same conclusions can be obtained based on both experiments and numerical modelling.

Feb 1, 2020

By Qiang Zhong, Bin Xu, Qian Li, Yong-bin Yang, Tao Jiang, Yan Zhang

The occurrence of different ringing behaviors in oxidized pellet kiln for two kinds of coal (A and B) with similar properties, is difficult to explain based on the relationship between kiln ringing and coal properties. In this paper, the interaction of coal ash with pellet scrap powder was considered by studying the cohering behavior of powders consisting of them. The results showed that the cohering briquette strength of pellet scrap powder increased considerably when mixed with a small amount of coal ash; a maximum could be reached when the mass percent ratio of coal ash was 1.5%; the strength of powder mixed with coal B ash was always higher in same firing system. This obviously illustrated that coal B caused a more serious ringing problem. The relevant mechanism was that the stronger reactivity of coal B ash made cohering briquette have a more perfect crystallization and a more compact structure.

Jan 1, 2015

By I. D. Ustinov, V. A. Arsentyev, A. O. Mezenin, A. M. Gerasimov

"The solid mineral raw materials of the sediment deposits containing the argillaceous variations such as the coal and the potash ores are the most multi-tonnage solid minerals mined and processed in the territory of the Russian Federation. Both types of the deposits have relatively simple geology aspects with large and medium-sized solids and as a rule, the most often, with the regular bedding which are characterized by the fitchery thickness and the internal structure. Such deposits are very difficult for mining and processing. The thermal modification of this of ores allows changing the physico-chemical properties of its components in such a way that their further processing - grinding, separation, transportation and storage can be carried out without the use of process water or significantly reduces its consumption. The purpose of the present study is to increase the efficiency of the mineral processing containing the layered aluminum silicate by reducing their negative impact on the basic dressing processes, the separation of suspended matters and the storage of waste. INTRODUCTION Many deposits of minerals are associated with the presence of layered silicates such as the argil, mudstones, argillaceous slate - highly hydrophilic mineral varieties which have the ability to swell in the water. This ability to self-disperse creates the great difficulties both for the extraction and the processing of such ores. Since the dressing of most minerals is associated with the use of wet processes, where in contact with water the swelling layered silicates are dispersed to a particle size of less than 50 µm, but due to their high hydrophylic property they form bonds that promote the formation of so-called structured suspensions having increased viscosity. In this case the structured suspensions make it difficult to perform the separation operations as the classification, the gravity and magnetic separation, the flotation and thickening and filtration operations."

Jan 1, 2018

By W. S. Wright, A. W. Tolonen

"INTRODUCTION The Mount Andrew iron deposit on Kasaan Peninsula, Prince of Wales Island, Southeastern Alaska, was examined in August 1942 by an engineer 4/ of the Bureau of Mines accompanied by geologists 5/ of the Federal Geological Survey. From October 20 to 27, 1942, two engineers 6/ of the Bureau of Mines made a further preliminary examination and took three large samples of magnetite and magnetite-copper ore for metallurgical testing. During the stunner of 1942 an investigation of the Mount Andrew-Stevenson-Mamie area, including topographic and geologic mapping and a magnetic survey, was made by geologist 7/ the Federal Geologically Survey. On May 31 and June 2, 1943, two Bureau of Mines engineers 8/ conducted a preliminary examination in which special attention was directed to trails, camp, and drill sites. They were accompanied on May 31 by L. A. Warner of the Geological Survey.During the period from September 1943 through September 1944 Bureau of Mines engineers 9/ completed a thorough investigation which included trenching, core drilling, and sampling. A Federal Geological Survey representative 10/ examined all trenches and cores for geological data.LOCATION AND ACCESSIBILITYThe deposit is situated at latitude 55º 31' N. and longitude 132º 18' W. on the north side of Kasaan Bay on Prince of Wales Island, Southeastern Alaska. The general location is shown on figures 1 and 2. The deposit is 5 miles southwest of the village of Kasaan and by water, 27 miles northwest of Ketchikan; the main tunnel portal is 7/8 mile north of the Mount Andrew landing on Kassan Bay."

Nov 1, 1947

Prefeasibility planning and cost estimation of conveyor systems has historically been undertaken by comparing fixed plant transport requirements to that of similar systems in service. This paper describes the development of a prefeasibility conveyor technical design and cost estimation application using Microsoft Excel Visual Basic for Applications (VBA) platform. The application tool known as D-Convey (Dachshund Convey) was developed with the goal enabling the end user:- to develop a technical model for conceptualised conveyor systems,- to perform economic analysis on the developed technical model, and - to conduct a comparative and risk analysis.An Excel VBA based platform was utilised to draw upon both the analytical and graphical capabilities of a spreadsheet. Some of the features of D-Convey system include a revolutionary dynamic graphical help system, known as the 'information pane' in lieu of traditional help files as well as the use of familiar graphical user interface elements such as the MS Office 2007 task ribbon. The D-Convey system incorporates material database allowing for mass handling prefeasibility estimation in other industries; it has been validated at a local quarry.

Dec 6, 2010

By O. C. Blade

The use of Diesel fuel continues to increase. In the United States during 1951 over 120,000,000 barrels of Diesel fuel oil were sold. The railroads used approximately 43.5 percent of this volume; industries such as smelters, mines, and manufacturing plants used about 12 percent; trucks, busses, tractors and bulldozers 20 percent; water craft 14.5 percent; and the remaining 10 percent was consumed by gas and electric utilities, the military forces, and oil companies. These figures were calculated from data issued by the Bureau of Mines. 2/ Complete data for 1952 are not yet available, but it is known that by December 1952 over 13 3/4 million barrels of Diesel fuel per month were produced by the country's refineries and by April 1953 the monthly production had increased to 1 4,333,000 barrels.3/ Information on the properties of this type of engine fuel is very important to the petroleum industry, engine manufacturers, and consumers. To supply this information the American Petroleum Institute and the Bureau of Mines, United States Department of the Interior, under cooperative agreement, are conducting annual surveys of Diesel fuel oil produced in refineries in this country.

Jan 1, 1953

By Matthew Wilcock, Kenichi Soga, Peter Wright

"This paper discusses how an existing grey cast iron segmental tunnel lining responds to construction of a new SCL tunnel transversely beneath with zero clearance; how the damage assessment for the existing tunnel was conducted for impact of longitudinal movement; how the tunnel is subsequently instrumented to observe both movement and stress manifestation at its longitudinal connections and how the results from the instruments compare with the prediction. An assessment of neutral axis of the tunnel in longitudinal flexure is also explored using interpolated horizontal displacement data from a conventional monitoring system. INTRODUCTION The Royal Mail Tunnel (RMT) (formely Post Office Tunnel or ‘Mailrail’) was constructed using semi-mechanised deep level construction techniques from 1914 and 1917 (Lee 1938). Commencing full commercial operation in 1926, the system was until 2003; conveying parcels the 6.5 miles between seven sorting offices in the center of London, and linking the system with main line rail stations, Paddington and Liverpool Street (The British Postal Museum & Archive 2013). A single tunnel of 2.74m internal diameter facilitated a bi-directional twin narrow-gauge (~611mm gauge) railway road system for electric driverless operation. The tunnel lining is segmental grey cast iron (grade 10) made up of six flanged segments and a smaller flanged key segment; constructed into a ring of width 508mm The external diameter of the tunnel is 2.971m. For further details of the tunnel lining and material properties are outlined by (Devriendt & Alhaddad 2014).London Underground Bond Street Station is a major station of the London Underground system in the very center of London; in its vicinity, the RMT runs west-east perpendicularly above the north south Jubilee Line tunnels. Historic survey record of the Jubilee Line’s (the then Fleet Line) construction in 1974 and its impact on the RMT case is documented in (Crossrail 1993): it is one of only a hand full of case-studies frequently cited when assessing the impact of new construction scenarios of this type; not least including the assessment of the same tunnel, at the same site some 40 years later, and the subject material for this paper: It noted significant vertical displacement of ~90mm to the RMT without noticeable serviceability or operational impediment."

Jan 1, 2016

By C. C. Templeton, J. C. Rodgers

A key step in feed water treatment for generating wet steam for thermal oil recovery is the removal of calcium and magnesiunt hardness by cation-exchange series softening. Knowing the solubility of any scale forming salts in brines at elevated temperatures is necessary for fixing the level to which the feed water must be softened. Such calcium sulfate solubility data, previously not available above 392F, were determined by the authors in a flow equilibrium apparatus mud will be reported elsewhere. These data were used to develop a method for predicting the solubility of anhydrite in hot water or steam droplets for saturated steam pressures as high as 2,000 psig (637F). (The calcium sulfate solubility product is represented by a combination of two factors, one reflecting the effects of ionic strength and the other accounting for the effects of complex ion formation in either calcium-magnesium-rich or sulfate-rich brines.) The method is applied to a calcium-magnesium-rich brine If moderately high salinity from a pilot hot-water flood, I nd to several sulfate-rich, low-salinity feed waters and l lowdown (cooled steam droplets) samples from steam s ak operations. The predicted calcium hardness levels corresponding to the calcium sulfate solubilities agreed reasonably well with the results of laboratory solubility determinations run on the field samples. Further testing of the method is needed for brines of other composition classes. Existing field cation exchange softeners in the cases tested are performing adequately since all the samples were found to be undersaturated with respect to calcium sulfate at their operating temperatures. Introduction Prevention of scaling caused by precipitation of calcium sulfate (anhydrite) is of considerable concern in connection with thermal recovery processes using wet steam or hot water. To avoid anhydrite precipitation in a heated system, an engineer must keep the product of the calcium and sulfate concentrations in the water or steam droplets below the value of the solubility product of anhydrite for the temperature and brine composition in question. Usually it is most practical to keep the concentration product lower than the solubility product by keeping calcium low in the presence of high sulfate, or by keeping sulfate low in the presence of high calcium. This can be done by a choice of combinations of natural waters and water treatment processes (such as series cation exchange softening to remove calcium). Until recently, few anhydrite solubility data, particularly for solutions containing other salts, were available for temperatures above 392F (211 psig steam); Marshall, Slusher and Jones' studied the CaS0,-NaCI-H,O system up to 392F and surveyed the work of previous investigators. To model natural brines, one needs to study the solubility of anhydrite in aqueous solutions of sodium chloride, sodium sulfate, calcium chloride, magnesium chloride and their mixtures. Since steam pressures as high as 2,000 psig (637F) may be involved in thermal oil recovery projects, a solubility study was conducted between 482 and 617F.' Discussed in this paper is the application of these data to the prediction of anhydrite precipitation in some practical steam soak and hot-water injection projects. Any simple method for predicting the solubility of an inorganic compound over a wide range of temperatures and solution compositions must be based on some assumptions, and therefore must yield approximate results. On the one hand, natural brines contain too many ionic species for all to be included in a simple scheme; on the other hand, there is no adequate theoretical basis for the exact prediction of solubility in even simple solutions of mixed electrolytes. However, it is possible at a given temperature to base a reasonable prediction scheme on two phenomena:'-' the increase in solubility with increasing total concentrations of all ions (as measured by the ionic strength; see the Appendix), and an increase due to formation of cornplexes between calcium ions and sulfate ions and between sulfate and magnesium ions. Stiff and Davis' developed such a scheme for predicting the solubility of gypsum (CaSO, ¦ 2H,O) in brines at temperatures u~ to 212F. However, for the higher temperaturei of present interest, the stable solid phase is anhydrite (CaSO,). This study involves a two-part method for predicting anhydrite solubility products. First, one predicts a value K, for a given ionic strength I and a given temperature T corresponding to mo./msr, = 1 from data of the CaS0,-NaCI-H,O system. Second, one determines a group of factors F .= F(Ca) • F(Mg) • F(SO,), where the individual factors account for increases in the solubility product due to complex formation by high concentrations, respectively, of calcium, magnesium and sulfate. Combining the two parts, one obtains the solubility product in molalities as

Jan 1, 1969