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By Bertrand Robinson

Great advances have been made in rubber-lined pumps for the pumping of mill pulps. The Canadian Allis Chalmers alone report ov.er 300 such pumps put into service during the past four years. Pumps in which both the casing and the impeller are rubber covered have proved most economical in handling the usual run of mill pulps, effecting large savings in power, maintenance, and shutdown costs. For the handling of pulps containing comparatively large, sharper edged /articles, rubber-lined casings with hard iron impellers have been developed by the pumping departments of Hollinger and Noranda. These rubber-iron combination pumps show an appreciable reduction in overall pumping costs as compared with the all-rubber and the all-iron pumps. The power efficiency is lower in rubber-iron than in all-rubber pumps but higher than in the all-iron pumps, with lower replacement costs due to the cheap iron impellers used. Where continuous operation is essential, however, and duplication of units to take care of shutdown time for replacement of parts is not within the expenditure budget of the company, all-rubber pumps are being used t0 a greater extent. As in all items pertaining to milling operations, the economics of the situation must be studied as closely as the technical details, to arrive at the most advisable practice.

Jan 1, 1939

By B. I. Whittington

This paper examines the effect of cation type (i.e. NH4+, Na+ and K+) and anion type (i.e. SO42- and C1-) on the extraction of nickel during the pressure acid leaching of a Western Australian laterite ore. The results are compared with testwork conducted with other Western Australian nickel laterite ores and the possible process implications of adding an additive to a plant autoclave are considered. Addition of either (NH4)2SO4, Na2SO4 or K2SO4 increased both the nickel extraction and the acid consumption, provided that the level of additive was not too great. For example, the nickel extraction of 93% increased to above 96% in the presence of additives, but decreased to 94% when, for example, NH4 levels increased from 7 kg/t ore to 21 kg/t ore. The relative stability of the jarosite species formed when additives were present influenced the amount of jarosite in the residue and, hence, both the final free acidity and overall nickel extraction. The use of Cl- versus SO42- salts as additives had little effect on overall nickel extraction or overall free acid values, although the presence of SO42- additives appeared to enhance nickel extraction kinetics over the first 60 minutes of the reaction. In contrast, manganese extraction was enhanced by the presence of Cl- additives.

Jan 1, 2004

By S. F. Guo, B. W. Zheng, X. L. Huang, S. W. Qi

"The study of mechanical characteristics of rock discontinuities under different shear deformation velocities is an important premise of rock slope dynamic response analysis. According to disposing and calculating the experimental results of previous research about peak shear strength of rock discontinuities under different shear deformation velocity of constant normal loading, the law of influence of shear velocity on the total friction angle is studied. Based on the research results, it can be found that the total friction angle of rock joint specimens varies in the form of negative logarithm with the variation of shear deformation velocity. It’s also indicated that the total friction angle of rock joints decreases with the increase of shear deformation velocity for rock joints of relative strong homogeneity and isotropy. However, the total friction angle of rock joints increases with the increase of shear deformation velocity for rock joints of relative strong heterogeneity and anisotropy and the latter amplitude of increase is less than the former amplitude of decrease. The physical property and microscopic geometry of rock joints play an important effect on the increase or decrease tendency and amplitude variation of total friction angle with the increase of shear deformation velocity.INTRODUCTIONThe rock slope dynamic response is largely restricted by rock discontinuities. Hence the study of dynamic characteristics of rock discontinuities, especially the dynamic shear characteristics is an important premise of rock slope dynamic response analysis (Qi et al., 2007). Seismic load is both dynamic load and cyclic load (Liu et al., 2011). Under the dynamic and cyclic shearing actions of seismic load, the rock slope which is stable under the condition of static load may slide along the rock discontinuities whose shear strength reduce and then the earthquake landslides occur. The strength degradation and deformation mechanism of rock discontinuities under the dynamic and cyclic shearing actions is one of the key problems to be solved in the work of earthquake prevention and control of engineering slope. Based on the above understanding, predecessors conduct some researches which focus on the shear behavior mechanical characteristics of rock joints under cyclic shearing actions (Plesha, 1987; Hutson & Dowding, 1990; Jing et al., 1992, 1993; Huang et al., 1993; Qiu et al., 1993; Homand et al., 2001; Lee et al., 2001; Jafari et al., 2003; Liu et al., 2011, 2013). However, there are a few researches about the mechanical characteristics of rock joints under different shear deformation velocities because of the restriction of shear apparatus. Crawford and Curran (1981) conducted a series of one-way cyclic direct shear tests on four kinds of natural rock joints under different shear deformation velocities varying from 0 to 200 mm/s. The tests showed that at low normal stresses the peak shear strength of soft rock joints exhibited an increase up to a certain velocity, after which it remained essentially constant. For rock joints of intermediate hardness, the peak shear strength was essentially independent of shear deformation velocity; whereas for hard rock joints, the peak shear strength of which showed a significant variation with the shear deformation velocity. Jafari et al. (2003) carried out a series of conventional triaxial tests on artificial rock joints of regular saw-tooth shape with axial loading rate from 0.05 mm/s to 0.4 mm/s."

Jan 1, 2015

By F. A. Auld

"During the period 1958-1980 seven deep shafts were sunk from the surface in the UK. From 1977 until 1989 sixteen deep shafts were sunk in the UK, all concrete lined. Subsequently from 1989 up to the present day no deep shafts have been sunk in the UK, a period of 30 years. Developments in the design and construction of deep shaft linings in the UK therefore were predominantly carried out throughout the period 1977–1989. This knowledge is recorded in several published papers by the author over that period which will be referred to in the paper. INTRODUCTION The paper includes a review of past precedent for the design of deep shaft concrete linings in the UK and sets out the principles for future designs, including the design load to be adopted and Factors of Safety (SFs) to be used in the design. Hydrostatic pressure increases with depth from the surface and therefore the concrete lining must increase in thickness and strength throughout its depth to resist the pressure. High strength concrete mixes were developed to enable economic linings to reach greater depths and these will be detailed. The ground conditions to sink through in the UK consist of predominantly competent (self-standing when excavated) rock, which can be water bearing, and hence a hydrostatic pressure resisting lining is required. The paper describes the construction measures needed to produce a dry shaft by way of pour length, joint detail, backwall grouting and joint sealing details. PAST PRECEDENT FOR UK DEEP SHAFT SINKING AND LINING Seven deep shafts were sunk from the surface in the UK from 1957–1977 over a 20-year period (Auld, 1987). These are listed in Table 1. Three shafts were for British Coal, two were for Cleveland Potash Ltd and two were for the Central Electricity Generating Board. The British Coal shafts were 5.486 m and 7.315 m internal diameter to depths of 550 m and 780 m, respectively. At 5.5 m internal diameter and a depth of 1150 m, the two Boulby Mine shafts for Cleveland Potash Ltd are currently the deepest shafts in the UK. The two Central Electricity Generating Board shafts of 5 m and 10 m internal diameter, to depths of 255 m and 440 m, respectively, were ventilation shafts for a pumped storage scheme. Six of the shafts were sunk by Thyssen (GB) Ltd and one by Cementation Mining Ltd."

Jan 1, 2019

By Floyd Smith

Based on underground observations made in .the coal mines of the Dominion Coal Company Ltd., this paper deals with the stress phenomena in the approach roads and headways and in the gob areas associated with the longwall method of total extraction. The deformation of roadways during development and the deformation of roadways during the total extraction period is delineated and presented in graphical form .. Conclusions are made as to the feasibility of the introduction of the retreat method of longwall extraction in one of the colhenes. The importance of future studies are enumerated, especially. those pertaining to the determination .of the opti.m.um sizes of protective pillars and to increasing the efficiency of the current methods of artificial roadway support.

Jan 1, 1967

By R. S. Boorman, H. G. Ansell

"Poor separation of lead from a copper concentrate of a major base metal producer was thought to have resulted from copper (0.2-0.4%) in the galena which caused it to float with chalcopyrite. No inclusions of copper mineral were detected which could account for the flotation of galena. The tendency for copper-bearing galena to float with chalcopyrite was confirmed by Hallimond-tube experiments in which the floatability of copper-doped synthetic galena (0.1-0.4% Cu) was approximately four times as high as copper-free galena. The difference in the cell edge (5.9338 ± 0.0003 A, Cudoped galena; 5.9361 ± 0.0002 A, Cu-free galena) indicated that the copper was lattice-bound and did not occur as submicroscopic mineral inclusions."

Jan 1, 1973

By Jun Deng

The aim of this paper is to study the scientificity and reliability of three coal gas indices used to predict coal fire disasters, namely Graham?s ratio, CO/CO2 ratio, Litton ratio and their different characteristics and service conditions. Data from a programmed temperature experiment were applied to check their veracity and accuracy. Each index performed well in detecting the level of a fire. We conclude that it is better to redefine the definition through experimentation before applying a given index. Integrated analysis of the results can provide reliable reference data for predicting spontaneous combustion of coal.

Aug 1, 2013

By D. B. Hyma

"The Raglan Ni/Cu property is located on the Ungava Peninsula in Northern Quebec, Canada, at a latitude of61°42' and a longitude of73°40', approximately 40 km southwest of Douglas Harbor. Geological reserves are estimated at 18 million tonnes, grading 3. 1 % nickel, 0.9% copper and smaller amounts of cobalt and platinum group metals.Extensive project development has defined the concentration process, concentrator sizing, tailings and environmental management required for this project.The grinding circuit selected is a fully autogenous primary grind, with pebble crushing and a pebble mill for secondary grinding to produce a product of 80% -70 microns for flotation.The flotation circuit is a simple circuit utilizing roughing, a regrind of rougher concentrate to 80% -20 microns, two stages of column cleaning with a cleaner scavenger bank on the column tails.Concentrate handling options were thoroughly reviewed because of the pyrophoric nature of the concentrate, remote site location and long distance to downstream processing. The preferred option, currently.is to dry the concentrate at Raglan to less than l % moisture and then pneumatically handle the powder.A detailed analysis of tailings placement options, suggests filtered tailings placement to be the preferable route for the Raglan site.INTRODUCTIONThe Raglan Project, as proposed by Falconbridge Limited, will develop extensive nickel-copper deposits in the Ungava Peninsula, Quebec, Canada. The project schedule and construction conditions in the project area are demanding. The Raglan mineral deposits have been the subject of numerous studies and evaluations over the last thirty years and the Phase I 1991 pre-feasibility document includes exploration information obtained in the 1989 and 1990 drilling seasons. This review concluded that an 800,000 tonnes of ore per year mining and concentrating complex located at Katinniq could produce 20,000 tonnes per year of nickel at competitive costs."

Jan 1, 1993

By A. G. Lylie

Introduction At the Britannia Mining and Smelting Company's mill, the equivalent of 2,500 to 2,800 pounds of copper sulphate crystals per day is made from copper which is precipitated from the mine-water. This copper sulphate is used in the mill for the recovery of sphalerite by2 flotation. From 1932 until 1936 it was produced by exposing the precipitate to air for thirty days and then dissolving the oxidized copper with dilute sulphuric acid. In 1936, the flotation of sphalerite was discontinued and, when it was resumed in 1947, steps were taken to try to improve the former method. The present paper outlines the way in which this was done, and describes the plant and procedure by which copper sulphate is now being made, and by means of which an appreciable saving is being effected. Aboratory Tests The previous work had established that the precipitate, which consists mainly of metallic copper, must be oxidized before the copper would dissolve in dilute sulphuric acid. Various methods for oxidizing it were tried but in the early laboratory work the only suitable one found was to heat the precipitate to 600°C. and hold it at this temperature for two hours. When this was done, approximately 90 per cent of the copper became soluble in .acid. This percentage was considered satisfactory for practical purposes, but the cost of roasting was prohibitive because only a small amount of roasted precipitate was required each day.

Jan 1, 1951

By A. O. Orumwense

Mill circumferential speed, the number of passes of pulp through the grinding chamber, media type, size and filling ratio were investigated in an attempt to determine how to effectively grind copper concentrates in a stirred mill. The stirred mill product fineness was enhanced to some extent by decreasing media size, high media filling, and an increased number of passes of the pulp through the grinding chamber. Shape also plays a major role in grinding media effectiveness, with spherically shaped media producing a finer size. The fineness of the product increases with increasing power consumption but the method of energy transfer is very important in energy utilization. The effect of the mill parameters on copper flotation was evaluated. Copper recovery was influenced by grinding media size, mill speed and the number of pulp passes through the grinding chamber.

Jan 1, 2006

By Jarret Thomson

An understanding of groundwater flow is essential for many aspects of mining. This is especially true for the process of shaft sinking through the sandstones of the Manitou Falls Group in the Athabasca Basin of northern Saskatchewan. Experience has shown that the hydraulic conductivities of these sandstones can be relatively high, especially in zones containing natural fractures. To develop a better understanding of the inflow potential into a shaft, a laboratory testing program was undertaken to investigate the hydraulic conductivity of fracture core samples from the Manitou Falls Group. This program involved the measurement of hydraulic conductivities under steady-state flow conditions, while cycling the effective confining pressure across a span that is representative of in-situ conditions. The change in fracture aperture was simultaneously recorded at each confining stress level. It was found that existing relationships relating aperture and flow did not accurately capture the behavior of the samples tested. The effects of fracture staining and infilling were also investigated, and were found to have a notable impact on the hydraulic conductivity.

Jun 1, 2012

By Gaston Gendreau, Marcel Allard

"Sidbec-Normines Inc. est une société formée de trios partenaires soient: Sidbec, British Steel Corporation et la Compagnie Minière Quebec Cartier. L'objectif de l'opération minière est d'exploiter à ciel ouvert le gisement d'hématite spéculaire de Fire Lake et de produire au concentrateur de Lac-Jeannine, près de la ville de Gagnon, 6 million de tonnes de concentré pour alimenter l'usine de bouletage de Port Cartier.Le présent exposé a pour but de fa ire ressortier les caractéristiques d'une opération dont la mine est située à plus de 100 km du concentrateur, d'en faire ressortir les particularités touchant le transport du personnel et du minerai. En plus, on traitera de l'importance dans une telle situation d'une organisation efficace dans la gestion des services et de l'opération (atelier, concasseur, entrepôt, etc.).IntroductionSidbec-Normines Inc . a entrepris l'exploitation minière du gisement de Fire Lake, le 1er janvier 1977. Le but de l'entreprise est de produire annuellement six millions (6 000 000) de tonnes de concentré d'hématite (oxide de fer) titrant 66% Fe au concentrateur de Lac-Jeannine a partir d'un minerai d'une teneur moyenne de 33% Fe, extrait de la mine de Fire Lake. Ce concentré est ensuite achemine à Port-Cartier et alimente I'usine de bouletage.Les installations minières de Sidbec-Normines sont situées a trois endroits différents : la mine à Fire Lake, le concentrateur à Lac-Jeannine et l'usine de bouletage à Port-Cartier. La mine de Fire Lake se situe à 83 km de la ville de Gagnon et à 100 km du concentrateur de Lac-Jeannine. Une route provinciale relie la ville à la mine et au concentrateur. Le minerai est acheminé de la mine au concentrateur par chemin de fer et le concentré est transporté par train sur une distance de 309 km à l'usine de bouletage de Port-Cartier."

Jan 1, 1982

By A. -M. Cadieux

During the geological synthesis of the Réservoir Pipmuacan area (NTS 22E) by the Ministère des Ressources naturelles (Québec), several ilmenite-apatite occurrences, some well-known and some recently discovered, have been examined. These occurrences are hosted in the Lac-Saint-Jean and Labrieville AMCG anorthositic suites. The Lac-Saint-Jean Anorthositic Suite (1160-1140 Ma), composed of multiple intrusions covering an extensive surface area, is characterized by labradorite plagioclase. The Labrieville Anorthositic Suite (1010-1008 Ma) is characterized by andesine plagioclase. It was previously known as the Labrieville Anorthosite, which was composed of a small isolated pluton located east of the Lac-Saint-Jean Anorthositic Suite. However, new geochronological data and field observations indicate that the Labrieville Anorthositic Suite in fact includes several intrusive bodies, namely the La Hache Monzonite and the Mattawa Anorthosite. A series of major structures (Saint-Fulgence, Pipmuacan, and Chute-des-Passes deformation zones) and their conjugate faults played an important role in the emplacement of the Lac-Saint-Jean Anorthositic Suite. The Saint-Fulgence deformation zone appears to have been involved in the emplacement of the Labrieville Anorthositic Suite. Oxide mineralizations are abundant in both anorthositic suites. Ilmenite, magnetite (± titaniferous), and apatite assemblages are found mostly in the labradorite-type anorthosites, while hemo-ilmenite, magnetite and apatite assemblages are associated only with the andesine-type anorthosites. Field works has revealed ilmenite-apatite mineralizations in a variety of settings, with grades reaching 48% TiO2, 16.2% P2O5, and 71.7% Fe2O3 (tot). Numerous oxide-bearing gabbronorites, often accompanied by or located near massive apatite-oxide accumulations (nelsonites), were discovered. Among these oxide-rich zones, breccia zones with anorthosite enclaves in an oxide matrix (ilmenite-magnetiteapatite) have been observed. Locally, ilmenite-apatite mineralization occurs as cumulate concentrations in ultramafic rocks. Evidence has been observed for immiscible magmas, for magmas differentiated from a mangerite or jotunite parent, and even for late magmas differentiated from the anorthosite magma itself (apatite-bearing anorthosite). Finally, the northern part of the Lac-Saint-Jean Anorthositic Suite hosts sulfide and vanadium mineralizations associated with ilmenite-apatite enriched zones, with grades reaching 1.48% Cu, 1.22% Ni, 1.6% Cr2O5, 0.25% Co, and 0.52% V2O5.

May 1, 2003

By M. Hames, K. Larmour-Ship, B. Grinbaum, E. Buchalter, R. Hackl, B. Wassink

Sodium cyanide continues to be the lixiviant of choice for gold dissolution. Many gold ore-bodies contain a significant amount of cyanide-soluble copper which increases the cost of processing due to high cyanide consumption and high cyanide destruction and disposal costs. Several cyanide destruction processes are in use today, however, there are just a few cyanide recovery plants operating. A solvent extraction process to recover cyanide has been developed which utilizes the organophosphorous extractants Cyanex 923, di-butyl-butyl-phosphonate (DBBP) or tri-n-butyl phosphate (TBP) in Bateman Pulsed Columns. Copper cyanide species are first converted to hydrogen cyanide (HCN) by acidification, with or without sulfide addition. HCN is extracted by the organic and stripped using a suitable base (eg. NaOH) resulting in a high strength cyanide solution (eg. NaCN) for recycle to the gold recovery process. Continuous pilot plant testwork on HCN extraction using a 40 mm diameter Bateman Pulsed Column demonstrated a cyanide recovery of greater than 99% with final levels of cyanide in solution of less than 10 ppm. These results illustrate the potential of this technology to recycle cyanide and to detoxify final effluent streams.

Jan 1, 2005

By B. E. Halbert, K. T. Himbeault, S. L. Fernandes, R. L. J. Phillips, B. J. Topp

The Beaverlodge uranium mining and milling facilities operated from 1952 to 1981 with about 94% of the ore extracted from the main underground mine and 6% from smaller satellite deposits. Decommissioning work occurred from 1982 to 1985 involving periods of shutdown, salvage and reclamation. Transition phase monitoring, leading to eventual delicencing commenced in July 1985. Over the last 15 years, discharge from the tailings management facility (TMF) and a fresh water stream, impacted during the operational phase by tailings spills, has improved in water quality for most parameters of concern. Loadings to the environment of three key contaminants (radium-226, total dissolved solids, and uranium) have consistently been less than during the operational phase with radium-226 having the greatest variability. Outstanding environmental issues associated with the recovering drainage system formerly used for tailings disposal, are being addressed in an enhanced environmental monitoring program to commence in 2000. Changes in water chemistry and the natural re-introduction of aquatic organisms are issues of concern. In the meantime, application for release from selected satellite areas commenced in 1999. This paper reviews the issues which have arisen during the transition phase, outlines how they have and are being addressed, and provides a comparison of original and current predictions of the recovery process under way at the former Beaverlodge mine site.

Jan 1, 2000

By M. U. Savich

In Canadian mines, ear muffs are now an essential part of safety equipment. Because of this, a research study was conducted to investigate their efficiency. The main characteristics of eleven commercially available ear muffs were investigated in the laboratory and analyzed by: (I) a psychophysical method; and (2) a physical method. These investigations showed the following effects: head size has a significant influence on the attenuation because of a different clamping force; the amount of hair trapped between the ear muff cushion and the head decreased ear muff attenuation; attenuation and comfort are not in a causal relationship; with the use of glasses and their adapters, attenuation decreases-the adapters are not effective sound barriers; there are no great differences in attenuation with neck movement; the efficiencies of various brands of ear muffs are not equal; ear muffs with a small cushion area start serving their purpose more quickly because the force per unit area is larger; a clamping force larger than 900 g wt, in most ear muffs, does not cause an increase in attenuation; attenuation characteristics (ANSI 224.22 - 1957) of ear muffs show some correlation with physical tests. Nine ear muffs out of the eleven were tested under uniform conditions in mines. Three ear muffs were found to be the best. All three ear muff s have bands passing behind the head. The ear muff with a support strap, which improves comfort and maintains a good fit during wear, showed the best attenuation. Causes of poor attenuation are numerous: bad mounting of ear muffs on helmets, improper fitting, interferency by hair and glasses, improper wearing by miners, unsatisfactory enforcement by supervisory personnel, incomplete training of miners, etc. Results of this research have indicated that none of the ear muff s tested in this study contain all of the characteristics desirable in an ideal unit. Because of unsatisfactory ear muff attenuation in working conditions (/5 dBA), it should be a mandatory requirement that workers wear both ear muff s and ear plugs if the noise level is higher than 105 dBA (various literature recommends t io dBA). The key to the solution lies in the following: the foreman must be capable of helping and controlling miners in their task of wearing ear muffs properly; the program must be introduced to miners; and constant contact must be maintained with manufacturers.

Jan 1, 1979

By E. Burdukova

Rheological measurements have found a wide array of applications in mineral processing research. Rheological properties of mineral suspensions are highly dependent on the mineral surface properties as described by DLVO theory, and the relationship between these properties and inter-particle interactions is well established. In this paper, rheological properties of mineral suspensions are used to study the differences in behaviour of isotropic talc and anisotropic zirconia minerals as a function of varying properties of the suspension medium, such as pH and polymer dosage, specifically carboxymethyl cellulose (CMC). It was found that the rheological tests when carried out in parallel with electrophoretic or point of zero charge measurements, clearly reveal differences between behaviour of the suspensions of isotropic and anisotropic minerals. These differences are further accentuated with the addition of carboxymethyl cellulose (CMC).

Jan 1, 2006

By H. Karakul

Determination of P-wave velocity (Vp), which is closely related to intact rock, is a nondestructive, easy and less complicated procedure. Due to these advantages, there is an increasing trend to predict the geomechanical properties of rocks from Vp. In addition to mineral content, cementing material and porosity, degree of saturation (Sr) are also other factors influencing geomechanical properties of the intact rock. However, up to the present, in the studies on the prediction of geomechanical properties of rocks from Vp, the effect of Sr has not been investigated. By considering this issue, in this study, it was aimed to correlate strength properties (uniaxial compressive and tensile strengths) and Young’s modulus with Vp of various rock types under different degrees of saturation. In addition, geomechanical properties of rocks were estimated from theoretical P- and S-wave (Vs) velocities, which were calculated based on their mineralogical compositions. For this purpose, fourteen different rock types were collected from several parts of Turkey and a comprehensive laboratory testing program was conducted. In the statistical analyzes, a series of different prediction relationships were developed by using independent variables such as Vp, Sr and effective clay content (ECC). Simple regression analysis results indicated that although prediction of the geomechanical properties of rocks from Vp at different degrees of saturation was possible, the equations developed would yield some under- or over-predictions. On the other hand, the multivariate equations developed have very high prediction performances and are very useful tools to estimate the geomechanical properties from the measured Vp at any Sr value. In addition to mineralogy, the variation in geomechanical properties with increasing Sr is also associated with the combined effect of porosity and clay content, which is first described in this study by the term Effective Clay Content (ECC). It is also noted that strength properties of rocks at any Sr may also be estimated using the empirical relations based on the theoretical Vp and shear-wave velocity (Vs) values, which are calculated from their mineralogical compositions.

Jan 1, 2015

By S. J. Laskowski

In potash ore flotation, carried out in NaCI-KCI saturated brine (about 6-7 molar KC1 and NaCI solution), long-chain primary amines are used as flotation collectors. Long-chain primary amines are poorly soluble in water and their solubility further decreases at high electrolyte concentration. For ionic surfactants there is a characteristic temperature (Krafft Point, KP) below which their solubility is too low for micellization. In a previous study, the effect of pH on the KP of dodecylammonium chloride in water was determined [Q. Dai and J.S. Laskowski, Langmuir, 7, 1361-1365 (1991)]. This paper deals with the effect of electrolyte concentration on the KP of dodecylammonium chloride. The derived theoretical relationship between the KP and the critical micelle concentration (CMC) for dodecylamine can be used to calculate the KP for electrolyte concentrations of up to 0.5 mol/L (about 8% NaCI-KCI brine). A simple experimental procedure for the determination of the KP for higher electrolyte concentrations is also described. The results show that the Krafft point of dodecylamine increases from about 17-18°C (in distilled water) to about 80°C at 16% brine saturation.

Jan 1, 2006

By D. D. Macdonald, G. Engelhardt

The accumulation of damage due to localized corrosion [pitting, stress corrosion cracking (SCC), corrosion fatigue (CF), crevice corrosion (CC), and erosion-corrosion (EC)] in complex industrial systems, such as power plants, refineries, desalination systems, etc., poses a threat to continued safe and economic operation, primarily because of the sudden, catastrophic nature of the resulting failures. Of particular interest in managing these forms of damage is the development of robust algorithms that can be used to predict the integrated damage as a function of time and as a function of the operating conditions of the system. Because complex systems of the same design rapidly become unique, due to differences in operating histories, and because failures are rare events, there is generally insufficient data on any given system to derive reliable empirical models that capture the impact of all (or even some) of the important independent variables. Accordingly, empirical models have generally failed to provide a robust basis for predicting the accumulation of corrosion damage in complex systems under realistic operating conditions. The alternative prediction philosophy is determinism, in which the development of damage is described in terms of valid, physico-electrochemical mechanisms with the output being constrained by the natural laws. The differential damage is then integrated along the corrosion evolutionary path for the system (i.e., over the future operating "history") to yield the desired integrated damage, which is the quantity that is most useful to an operator. In this paper, we review the theory of predicting corrosion damage within the framework of Damage Function Analysis (DFA), with particular emphasis on the pitting of aluminum in chloride solutions and on the accumulation of damage from SCC in Type 304 SS components in the primary coolant circuits of Boiling Water (Nuclear) Reactors (BWRs). These cases have been selected to illustrate the various phases through which localized corrosion damage occurs.

Jan 1, 2005