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By A. F. Matheson

The St. John Del Rey Mining Company, Limited, is an English company owning 150 square miles -of mining lands near Belo Horizonte, Minas Geraes, Brazil. The area is 2,300 to 5,000 feet above sea level, with a pleasant and healthy climate. Bedrock is Precambrian. The Nova Lima series of metamorphosed sediments and some volcanics is overlain uncomfortably by the Minas series of quartzites, itabirites. etc. Batholithic granite and gneiss cut both series and basic dykes cut all these rocks. There are important deposits of gold, iron, and manganese on the Company's holdings, as well as occurrences of arsenic, antimony, cobalt, nickel, dolomite, day, quartz, -ochre, bauxite, kyanite, and asbestos. Except for gold and consequent recovery of arsenic, all the other materials are relatively unexploited. The Company operates the Morro Velho gold mine and the Espirito Santo and Raposos gold mine. The Morro Velho mine was purchased in 1834 for £56,000. To the end of 1952 it had produced 7,000,000 troy ounces of gold from 15,000,000 short tons of ore. The ore z?ones are replacement deposits in a sinuous siliceous dolomitic rock locally termed "lapa seca," and plunge east, near surface at 45 °, at 8,000 feet at 15°. The ore minerals are pyrrhotite, arsenopyrite, pyrite, and chalcopyrite. Gold is finely distributed and almost nowhere visible. Ore reserves at the end of 1952 were estimated at 5.5 million short tons grading 0.39 oz. gold per ton. Chances exist for new ore within the mine area. The Espirito Santo and Reposos mine, in folded banded iron formation, has mineralization similar to Morro Velho but sulphides are less abundant. The mine to a depth of 2,500 feet has estimated ore reserves of 1.5 million tons of an average grade of 0.28 oz. gold per ton. New ore may be expected both laterally and at depth. To the end -of 1952, the ?Company had paid dividends of almost £4,- 600,000, largely earned from the operation of the gold mines.

Jan 1, 1956

By F. Rivard, M. G. Drouet, W. S. Ruff, P. Carabin

"In both the hot rotary-salt-furnace (RSF) treatment of aluminum dross and the cold ball-millsieving (BMS) treatment of zinc dross, enormous amounts of energy and recoverable metal are wasted and large amounts of greenhouse gas are produced. Such wastes and the environment pollution could be avoided by using the DROSRITE PLUS™ technology. Economic and GHG production comparisons between the presently used industrial treatment processes and DROSRITE PLUS™, supported by over one hundred tests conducted in Canada, the US and Europe, are presented. The savings, with DROSRITE PLUS™, would be about $191 and $418 per MT of aluminum and zinc dross, respectively.INTRODUCTIONDross is a material, which forms on the surface of molten non-ferrous metal, such as aluminum or zinc, during melting, metal holding and handling operations when the molten metal is in contact with a reactive atmosphere. Dross normally consists of metal oxides entraining a considerable quantity of molten free (unreacted) metal, and for economic reasons it is desirable to extract the free metal before discarding the residue. In the case of aluminum dross, recovery of the metal is usually carried out by treating the dross in a furnace at a high temperature (Peterson et al., 2002). By contrast, cold zinc dross is crushed in a ball mill followed by sieving to separate the coarse metal portion from the fine oxide residue.The conventional aluminum dross treatment process, using gas or oil-heated rotary salt furnaces (RSF), is thermally inefficient and environmentally unacceptable because of the salt slag and CO2 produced from the combustion of fossil fuels. In the past several years, a number of salt-free processes have been developed and some of these have found limited commercial use (Gripenberg et al., 1994; Lavoie et al., 1990). In all these dross treatment processes, heating of the cold dross in a rotary furnace requires an external energy input that varies between 375 and 2,500 kWh per (metric) tonne of dross. Molten metal separated during processing of the heated dross is tapped, and the remaining solid residue is discharged from the furnace."

Jan 1, 2012

By M. H. Pettibone

Sohio Petroleum Company's new L-Bar uranium mill near Grants, New Mexico. refines 2722 kilograms of yellowcake daily from 1360 metric tons of ore produced at Sohio 's J.J. No. 1 mine and other nearby mines. This paper follows the ore from the mine through the various processing steps - semi-autogenous grinding, acid leaching , countercurrent decantation, solvent extraction , ammonium diuranate precipitation, washing and drying, and tailings disposal.

Jan 1, 1978

By D. L. Morgan, J. A. Butterfield

"Geological data, production trends and current projects underway suggest that enough molybdenum will be available from more diversified sources to meet the world's growing demands. The growth in molybdenum consumption has been primarily related to its beneficial effects as an alloying agent in steel. This rapid growth has been deliberately fostered by stable prices, adequate supply and application research. The molybdenum industry is now in a process of change which has been seen in several other metals, such as aluminum and nickel. As supply sources have become more diversified, the market has become more competitive. The recent drop in consumption has led to excess production capacity, accumulation of substantial producer inventories and increased market uncertainties. While consumption is expected to increase in the next two to three years, it will take some time to absorb the excess capacity and inventory. The increased proportion of by-product capacity indicates that prices may become more variable. Producer discipline will be required to prevent serious price erosion in times of surplus. Future prices may not continue to increase with inflation. For the longer term, several factors favour the increased consumption of molybdenum. Engineering requirements are becoming more severe and molybdenum alloys can help to meet these changing needs. In addition, consumers can rely on a large and increasing supply of molybdenum. A 7 per cent growth rate in consumption can probably be sustained through the next decade, but new applications and reasonably stable prices will be needed to make this possible."

Jan 1, 1972

By R. Pandher, R. Schonewille, N. Tripathi

Advanced process modelling tools were developed for the Xstrata Nickel Sudbury Smelter flow sheet using a combination of FACTSAGE TM METSIMTM and ARENATM software. These tools were employed to assist with plant optimisation, emission control, process design, troubleshooting and case studies as applied to the smelter. The development of process modelling tools in pyro-metallurgy commonly involves an in-depth study of the therm o-chemical properties (heat capacity, liquidus temperature, etc.) of all high temperature phases, usually matte and slag. The preferred tool for this purpose is FACTSAGETM, a well-known then-no-chemical modelling software package. The results from the therm o-chemical model have been subsequently incorporated into the development of a process model for the entire smelting facility using the METSIMTM platform. Such process model also includes a number of special features adopted to effectively simulate the complex industrial phases; matte and slag systems. To ensure the robustness and reliability of the process model, several process parameters and assumptions were verified with laboratory and plant data. Consequently, the model includes the ability to examine the impact of a number of plant parameters on potential plant performance. Primary variables are the percent sulphur elimination during concentrate roasting, furnace matte grade and degree of matte metallization. Key output parameters include operating temperature, furnace coke requirement, sulphuric acid production, CO2 emissions and overall energy requirements. Selected outputs from the process model (for example blowing time, slag production rate and matte converting rate) can then be utilised in the development of a discrete event model (DEM) for the smelter using ARENATM software. Incorporation of reliable and validated mass balance parameters enhances the robustness and reliability of the DEM model. The integration of then-no-chemical, process and DEM modeling tools has a distinct advantage in planning plant trials and examining process design initiatives at Xstrata Nickel's Sudbury Smelter. The present paper discusses the development of these three models and the synergies existing among them. Typical results from all three models are also presented.

Jan 1, 2011

By R. Pandher, R. Schonewille

Advanced process modelling tools were developed for the Xstrata Nickel Sudbury Smelter flow sheet using a combination of FACTSAGETH METSIMTM and ARENATM software. These tools were employed to assist with plant optimisation, emission control, process design, troubleshooting and case studies as applied to the smelter. The development of process modelling tools in pyro-metallurgy commonly involves an in-depth study of the therm o-chemical properties (heat capacity, liquidus temperature, etc.) of all high temperature phases, usually matte and slag. The preferred tool for this purpose is FACTSAGETM, a well-known then-no-chemical modelling software package. The results from the therm o-chemical model have been subsequently incorporated into the development of a process model for the entire smelting facility using the METSIMTM platform. Such process model also includes a number of special features adopted to effectively simulate the complex industrial phases; matte and slag systems. To ensure the robustness and reliability of the process model, several process parameters and assumptions were verified with laboratory and plant data. Consequently, the model includes the ability to examine the impact of a number of plant parameters on potential plant performance. Primary variables are the percent sulphur elimination during concentrate roasting, furnace matte grade and degree of matte metallization. Key output parameters include operating temperature, furnace coke requirement, sulphuric acid production, CO2 emissions and overall energy requirements. Selected outputs from the process model (for example blowing time, slag production rate and matte converting rate) can then be utilised in the development of a discrete event model (DEM) for the smelter using ARENATM software. Incorporation of reliable and validated mass balance parameters enhances the robustness and reliability of the DEM model. The integration of then-no-chemical, process and DEM modeling tools has a distinct advantage in planning plant trials and examining process design initiatives at Xstrata Nickel's Sudbury Smelter. The present paper discusses the development of these three models and the synergies existing among them. Typical results from all three models are also presented.

Jan 1, 2011

By H. D. S. Miller

"Artificial stope support has become an essential component of many underground mining operations. Because the use of cable bolts in open stopes is a relatively new concept, most support is still designed by trial and error or by rules of thumb. This often results in costly overdesigned support or inadequate support which leads to stope failure.This paper proposes guidelines to determine support requirements using the stability graph method. The stability graph method is an empirical open stope design technique that takes into account the key factors that influence stope stability. The factors for the design of a cable bolt support system include bolt length, bolt intensity and the original rock mass competency and can be estimated using empirically calibrated charts. The empirical charts were developed based on more than 60 case histories of cable bolting success and failure in Canadian open Slope mines.The concept of pre reinforcement and supp ort stiffness will also be discussed.INTRODUCTIONArtificial support, in the form of rock anchors, has become an important component of all underground mining operations because its stabilizing effect contributes to make underground workings safer. There are several types of rock anchors featuring different properties and having a variety of functions. This paper focusses on grouted cable bolt applications in large open stope mining. Such a support system may improve the competency of the disturbed rock mass to a point approaching the undisturbed rock quality by limiting joint movement and dilation. This results in more stable, possibly larger and, thus, more efficient production stopes."

Jan 1, 1989

By R. C. Becker

Welding is playing an important role in the manufacture of construction equipment as used in the mining industry. It provides design possibilities which are unique to this method of manufacture, and normally makes possible lighter weight but stronger products, which can be a definite advantage to a user. Welding is an industry that has experienced major developments over the past decade, all of which have improved our capability to make better welds and make them more economically. International Harvester Company has been introducing these newer welding methods into its manufacturing plants, particularly those producing construction equipment, just as fast as their value has been proven. This paper discusses how modern welding methods are contributing to the manufacture of strip mining equipment.

Jan 1, 1966

By C. Hunt, J. Vivas, D. M. Allen

"In this paper we present the results of a combined remote sensing - numerical modelling study to improve our understanding of groundwater seepage in open pit and natural rock slopes, and to investigate the interaction between groundwater, in-situ stress conditions and brittle fracture. The location of seepage is a key element in the characterisation of rock slope stability in open pits and natural slopes; definition of the fracture network geometry and its inter-relationship with seepage, however, remains a challenge in engineering practice. Current techniques used to characterize groundwater seepage locations require direct access to the rock slope for a detailed and exhaustive investigation, and can be severely limited due to access and the limited coverage of the survey methods both with respect to the height and length of the sampled rock slope. Herein, we describe remote sensing methods, which allow the collection of structural and seepage information over a wide spatial area. Remote sensing techniques are shown to have the potential to provide additional insights into the orientation and general connectivity of fractures that may play a major role in the general stability of a rock slope. A preliminary methodology for the use of remote sensing in the characterization of seepage zones in a natural slope through the application of ground-based LiDAR and Infrared Thermography (IRT) is presented.One of the most challenging problems in rock slope engineering is the realistic simulation of fluid flow through fractured and deforming rock slopes. Deformation and the development of brittle fractures can cause significant local changes in the permeability and strength of the rock mass, potentially affecting rock slope performance. Understanding fluid flow through fractured and deforming rock slopes, especially in highly-stressed environments is of great importance for slope stability analysis. Changes in the interconnectivity of fractures during slope failure are an important, yet are relatively unstudied in rock slope engineering. We present the results of hydromechanical UDEC-Trigon rock slope models focussing on the potential role of brittle fracture in rock slope failure, its interaction with groundwater pressures, and the influence of the assumed in-situ stress ratio. Damage intensity parameters are used to characterize damage within different regions of a biplanar slope failure."

Jan 1, 2015

By Alan Rice

Abstract-The mechanism by which stratiform ore deposits of PGE (platinum-group elements) are laid down in ultramafic igneous complexes is not completely clear. Early studies by the author and coworkers on numerical analyses of the convective cooling of low-Rayleigh-number magma chambers examined the effect of suspended crystal load on fluid density, and raised the possibility that the growth of the suspended crystal load during cooling could split a magma chamber into several convecting layers. The lower layers would have a higher content of refractory phases than the upper layers, which would consist of more evolved melt. This paper considers numerical modelling, as well as theoretical and experimental work in other fields dealing with suspended loads in fluids. The calculations, which are based on the physics of convecting magmas, yield quantitative relationships consistent with the observation that economically interesting stratiform PGE deposits are restricted to large magma bodies, and also yield estimation of the depth in a magma chamber at which certain grades of mineralization may occur.

Jan 1, 1997

By Alan Rice

The mechanism by which stratiform ore deposits of PGE (platinum-group elements) are laid down in ultrama?c igneous complexes is not completely clear. Early studies by the author and coworkers on numerical analyses of the convective cooling of low-Rayleigh-number magma chambers examined the effect of suspended crystal load on ?uid density, and raised the possibility that the growth of the suspended crystal load during cooling could split a magma chamber into several convecting layers. The lower layers would have a higher content of refractory phases than the upper layers, which would consist of more evolved melt. This paper considers numerical modelling, as well as theoretical and experimental work in other ?elds dealing with suspended loads in ?uids. The calculations, which are based on the physics of convecting magmas, yield quantitative relationships consistent with the observation that economically interesting stratiform PGE deposits are restricted to large magma bodies, and also yield estimation of the depth in a magma chamber at which certain grades of mineralization may occur.

Jan 1, 1997

By M. A. T. Cocquerel, J. G. Eacott

"Simulation techniques may be used to optimize existing processes and plant operations, and in plant design at the engineering study stage of a project . This paper describes the latter application, using a computer, to optimize the concentrate stockpile requirements of a modern copper smelter.A large open-pit mining operation is envisaged and it is assumed that copper concentrate is smelted in two flash furnaces. The proposed mining plan gives rise to metaffurgical considerations in smelting which dictate that concentrate blending is carried out in the early years of operation in order to eliminate wide variations in the grade of concentrate charged to the furnaces . Stockpiling facilities are therefore necessary for blending purposes and also to provide a strategic reserve of concentrate to ensure continuity of concentrator and smelting operations.The objective of the study is to determine the optimum size of concentrate stockpile required to take account of both metaffurgical and strategic considerations. Two separate simulation models are developed to achieve this objective. The first model is used to determine the minimum size of stockpile necessary for blending purposes to smooth out variations in concentrate grade between 15 - 60% Cu, with associated 34 6% Fe, respectively, and ensure that the concentrate fed to the furnaces does not faff below 12% Fe, which is considered a minimum for good smeltability.The second simulation model covers a projected three-year operating period and indicates the maximum size of stockpile which is likely to develop during scheduled and unscheduled shutdown periods in the concentrator and smelter.Covered storage volume and conveying facilities for the optimum size of concentrate stockpile can be designed based on the results generated by the simulation models."

Jan 1, 1980

By C. H. Wright

Introduction The rapidly expanding and increasingly complex Canadian industrial structure, with the mining, metallurgical, and chemical industries as a large integral part, has, in recent years, brought greatly increased importance and value to our industrial minerals. In the modern economy of our mineral industry the importance which is due the non-metallics has been somewhat overshadowed by the great value of our large metal production and, in addition, by the glamour and fascination usually associated with the mining and treatment of gold ores. The term 'Industrial Mineral' is used in this paper in its usual sense and refers to non-metallics other than fuels. Coal and petroleum products, including natural gas, are considered as industrial minerals in those applications in which they are used for strictly chemical process purposes. Certain reduction metallurgical industries are so closely allied to chemical industries that for purposes been of this discussion no attempt has made to differentiate between them. Chemical industry in Canada today is a fairly large factor in our national economy, whereas in 1898, when the Canadian Mining Institute was born, it was very small indeed. Chemical concerns are largely dependent on industrial minerals for raw materials and process supplies and, as the country has developed industrially, so have the demands for non-metallics increased, not only by chemical industry but also by other large consumers, such as the construction and metallurgical industries. At the present time there is a greater than normal incentive prevailing for new discoveries, due to the serious lack of balance that exists in our import and export trade. This fact has resulted in intensive efforts to rectify the situation by locating new deposits and re-assessing those already known in an effort to enlarge and improve our home production of raw materials and also to extend their processing in Canada for our own needs and for export. The rapid advances in science and technology that have taken place since 1900 have also resulted in many cases of beneficiation and utilization of otherwise too low grade materials in order to satisfy current demands. The purpose of this paper is to indicate the history and the trends of the utilization of industrial minerals in established industry and to indicate the important part played by non-metallics in connection with the opening up of new industries. Some consideration has been given to the continual competition between natural and 'synthetic products and to the general tendency towards more rigid specifications.

Jan 1, 1948

By C. Gravel, A. Fathi, P. Rivard, G. Ballivy, Z. Moradian, M. Quirion

Knowing shear mechanism of discontinuities under monotonic and cyclic loading conditions is a key factor in stability analysis of rock slopes and rock foundations. In this paper, the effect of cyclic loads on the shear mechanism of joint asperities is described. For this purpose, a fresh tension-split joint from a granite block was used as a reference and thirty five mortar replicas were fabricated. Cyclic shear tests were conducted on replicas under low values of constant normal load (CNL) using a servo-controlled loading system. Tests were performed in two consecutive steps; load-controlled and then displacementcontrolled. In the load controlled part, after initial increase of shear stress to 0.25 MPa, the test was stopped for 2 minutes, then increased to 0.5 MPa, and finally decreased to 0.25 MPa. This process was repeated ten times. At the end, the test was continued up to 10 mm shear displacement under displacement-controlled loading in order to pass the peak shear strength and reach the residual strength. Characterizing joint surface and modeling of involved asperities during the tests was undertaken using a Matlab code developed with new mathematical expressions. The algorithm used in the code is based on three-dimensional coordinates of the scanned joints’ surfaces before and after the test. It was found that a high percentage of degradation happens during the first cycle of loading and during the other cycles, degradation occurs gradually. While comparing tests conducted in monotonic and cyclic loading conditions, it was observed that under low number of cycles, the pronounced mechanism is consolidation of the joint surfaces. This consolidation increases contact areas and, therefore, shear strength parameters.

Jan 1, 2015

By R W. Drybrough

The program to increase production at Sherritt Gordon's Lynn Lake property, which began in 1956, included increasing the rope speed and the horsepower of the ore hoist at the "A" shaft. Because of the limited power sup-ply from the two 7,000-hp. hydroelectric plants, and the ? 3,600 hp. predicted for the combined hoisting requirements of the three production shafts, it was considered desirable to lessen the impact of this type of load on the relatively small power system by equipping all future hoisting arrangements with Ward Leonard direct-current drives. The manually operated 8-by 4-ft. hoist at the "A" shaft had a rope speed of 1000 f.p.m., and was driven by a 385-hp., 380-r.p.m. wound rotor motor with liquid rheostat control. This A.C. drive was replaced by a semi-automatic Ward Leonard direct-current drive with a 515-hp., 566-r.p.m., shunt wound motor, providing a rope speed of 1,500 f.p.m. During several months preceding the con-version, all possible preparations were carried out to keep the changeover period to a minimum, and this resulted in a total shutdown time of twelve days. The capability of the "A" Shaft hoist was increased from 109 tons per hour to 134 tons per hour, and both mechanical and electrical maintenance were reduced considerably. The total cost of the conversion amounted to $130,000. The hoistmen who had been required for the manual A.C. drive were transferred to the new Farley shaft, and the reduction in operating labour costs of the "A" Shaft hoist

Jan 1, 1965

By S. K. Kawatra, S. J. Ripke, T. C. Eisele

It was determined by the authors that the water that remains in the filter cake after filtration in iron ore concentrators can contain several hundred times greater concentrations of calcium ions and other cations, due to surface chemical effects carrying the ions along with the water. Filter cake from two plants was analyzed. The water retained in samples of magnetite concentrate filter cake in Plant 1 contained 5088 ppm calcium and 5995 ppm magnesium, while the Plant 2 filter cake contained 231 ppm calcium and 119 ppm magnesium. These levels were dramatically elevated compared to the water that was removed from the concentrate by filtration for recycle to the plants (9 ppm calcium/15 ppm magnesium for Plant 1, and 11.9 ppm calcium/9.3 ppm magnesium in Plant 2). In addition to possible effects on agglomeration performance, the presence of these cations also affected the efficiency of filtration. In order to reduce the effects of these cations on filtration in Plant 2, carbon dioxide was injected into the slurry before it entered the filter press. This was found to increase filtration rates by up to 23.7%. Comparison of the results from the two plants shows that the concentrations of cations present in the filter cake will vary greatly from plant to plant, with correspondingly large variations in their effects on plant operations.

Jan 1, 2004

By M. B. McClenaghan

"Abstract - The Matheson area of northeastern Ontario is of great interest for mineral explo­ ration because of its geological similarities with the adjacent Timmins, Kirkland Lake and Larder Lake gold camps. Exploration in the area, however, is hampered by the presence of an extensive and thick cover of glacial sediments. For this reason, till geochemistry has be­ come an important exploration method. The Ontario Geological Survey&apos;s Black River -Matheson (BRiM) reconnaissance till sampling project, carried out between 1984 and 1988, was designed to aid exploration in the Matheson area by documenting the Quaternary stratigraphy and providing a database of till geochemistry. Till samples were collected by backhoe trenching of surface pits in areas of thin drift ( < 5 m) and by sonic overburden drilling in areas of thicker drift. This paper summarizes the results from the shallow till sampling component of the BRiM project.Two hundred and eighty-two surface samples were collected from Matheson Till, the youngest till sheet in the area, which was deposited during the Late Wisconsinan. For each sample, the non-magnetic heavy mineral (>3.3 S.G.) and fine (-250 mesh) till fractions were analyzed geochemically. In addition, visible gold grains were recovered by panning the heavy mineral fraction. Five areas that display multi-element anomalies in both till fractions warrant further investigation: (1) western Egan Township, overlying the Bradley Lake Syenite; (2) around and south of the Munro and Croesus mines, in Munro and Guibord townships; (3) central Garrison Township overlying the Garrison Stock; (4) south of Ore Car Lake in northern Thackeray Township; and (5) southeastern Harker Township. In these areas, Matheson Till has a local provenance and the bedrock sources for these anomalies are nearby in the up-ice (north­ northwest) direction. Due to the fine-grained nature of gold in bedrock deposits in the BRiM area, the small size of most gold grains recovered from till samples (<50 1-1m) and the variable distribution of gold in the heavy mineral concentrate and fine fractions, the fine fraction in addition to the more commonly used heavy mineral concentrate should be used for gold exploration.Surface till samples have been affected by weathering to a depth of s3 m. Weathered till is characterized by a very low carbonate content in the matrix fraction, the absence of sulfide grains in the heavy mineral concentrate and higher concentrations of copper, nickel and zinc in the fine fraction than in the heavy mineral concentrate. As a result of the weathered/ oxidized nature of the surface till samples, the fine fraction is a better sampling medium for base metal exploration."

Jan 1, 1992

By J. W. Craig

THERE are, broadly speaking, three classes of refractories: acid, basic, and neutral. Fireclay, diaspore, silica, and the sillimanite group of minerals are included in the acid class, which for the most part are not very resistant to basic slags. The neutra! class includes chrome, graphite, and silicon carbide, while most important in the basic class are magnesite and dolomite. Although chrome is a neutral refractory, it has no sharp distinction from magnesitic refractoriness. The two are mineralogically (1) and chemically related, and there is available on the market a complete range of brick from straight chrome to straight magnesite. In many indus trial applications, one. type may be replaced by another. The present paper is confined entirely to such refractories. The following types of basic and neutra! brick, each sold under sorne special trade name, are available for use in Canada: (1) Burned chrome from crude ores (2) Burned chrome from treated ores (3) Chemically bonded (unburned) chrome-magnesite ( 4) Burned chrome-magnesite (5) Chemically bonded ( unburned) magnesite-chrome (6) Chemically bonded (unburned) high-iron magnesite (7) Burned high-iron magnesite (Regular) (8) Burned low-iron magnesite (9) Burned olivine-magnesite (10) Burned magnesitic dolomite-chrome (Magnecon) (11) Chemically bonded magnesitic dolomite-chrome (Magmecom) (12) Dolomitic brick

Jan 1, 1936

By W. Graham

"IntroductionEFFLORESCENCE is herein considered to be any deposit of salts on the surface of a masonry structure that is brought from within or through the structure by capillarity and deposited by evaporation. Usually, efflorescence is white although green, yellow, and brown efflorescence is sometimes observed.The common white efflorescence almost always consists of sulphates of the alkali and alkaline earth metals and calcium carbonate, although sodium chloride is frequently present in structures erected near the sea shore.The first and most obvious result of the presence of soluble salts in masonry is the unsightly accumulation of these salts on the surface. This is particularly noticeable early in its life and is frequently fugitive ( 1), as much of the salt is soluble and is gradually washed away by rain. This removal can usually be facilitated by scrubbing; the structure with dilute hydrochloric acid.A more serious effect is the continuous accumulation of soluble salts as a result of ingress of sulphur acids in rain water or water from the ground. This may eventually cause spalling and disintegration by crystallization of salts in the pores of brick and mortar. An example of this type of failure, resulting from the crystallization of calcium sulphate, is discussed by Hardesty (2). Butterworth (3) describes similar failure resulting from •crystallization of magnesium sulphate."

Jan 1, 1954

By Subagyo, Geoffrey Brooks, Ken Coley

The generation of droplets and their subsequent reaction in the emulsion is critical to the overall kinetics of oxygen steelmaking. High temperature experiments have been performed at McMaster University to study this behavior. The results from this work and other previous studies has formed the basis of a number of physical and chemical models that attempt to describe the critical aspects of droplet behavior in Oxygen Steelmaking. These models include semi-empirical models for predicting droplet generation rate, droplet size distribution and droplet residence time as a function of blowing parameters.

Jan 1, 2004