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By G. L. Bartlett

"INTRODUCTION The major objective of our research is to help reduce the incidence and severity of coal worker's pneumoconiosis (CWP). To that end, this project is designed to improve our understanding of the processes that lead to pulmonary dysfunction following mine dust exposure, and how those processes might be interrupted or attenuated. The response of the lung ' to inhaled particles is complex, and the course of development of disabling CWP is slow and unpredictable. From among the numerous cellular and molecular interactions involved in the pulmonary response to inhaled particles, this project is focussed on the role that the pulmonary alveolar macrophage (PAM) may play in regulating the activity of fibroblasts.The PAM is the lung cell that has the most immediate and the most obvious interaction with inhaled particles. Within a short period after particles are arrested in the alveolus of the lung, they are phagocytized (engulfed) by these specialized cells. The PAM then has a diverse potential repertoire of subsequent activities. Which reaction actually ensues is determined, in large part, by the nature of the phagocytized _particles. Activated PAMs produce a variety of products that may affect adjacent lung tissue, including superoxide free radical, elastase, collagenase, prostaglandins, platelet activating factor, etc. Those may well be important in the pathogenesis of CWP, but they are beyond the scope of this project. Background information that is cogent to this project has come primarily from investigations using animal models of silicosis and asbestosis. PAMs that have ingested silica particles synthesize and release molecules that control the behavior of surrounding cells. One such mediator is interleukin-1 (IL-1), a molecule that plays a central role in many aspects of the response to injury. It can stimulate fibroblasts (the cells that help to hold tissues together) to release the enzyme collagenase, resulting in breakdown of the structural collagen fibers that support the lung tissue. IL-1 also stimulates fibroblasts to undergo mitosis and to proliferate, which is an initial stage of fibrosis. Certain stimulants cause PAMs to release fibroblast growth factors (FGFs) that are distinct- from IL-1. Under other circumstances activated PAMs synthesize and release molecules that stimulate fibroblasts to accelerate synthesis of collagen fibers, thus contributing to fibrosis. Although these observations provide a valuable precedent for analysis of the mechanisms involved in CWP, their relevance to CWP cannot be assumed since most of those studies involved macrophages or fibroblasts obtained from tissues other than the lung, and because almost none of them have used CMD as the stimulating particles. Therefore, the goal of this project is to learn how exposure to CMD affects the behavior of PAMs, and in turn how products of dust-exposed PAMs affect fibroblasts and the process of fibrosis in the lung."

Jan 1, 1988

By Charles L. Kimbell

The year 1986 was not a good year for the world's mineral industry from several viewpoints. Levels of production, both of crude minerals and processed forms, registered declines in the cases of a greater number of commodities than the number that recorded increases. The overall value of world crude mineral production was estimated to have increased, but only very slightly in terms of constant dollars to nearly $997 billion. Although there were modest increases in the consumption of all major fuels and most major metals, the latter at least apparently resulted more from drawdowns of inventories than from increased production (fuel consumption increases did come from higher output levels), and consumption of most major fertilizer and chemical commodities (nitrogen, phosphate, and sulfur) were at lower levels than those in 1985. Prices for a number of mineral commodities declined, headed by the very substantial drop in world crude petroleum prices, but also including downturns for a number of metals and industrial minerals as well. There was insufficient information to reliably fix the level of the dollar value of world trade in minerals, for while output was up in the case of some large-volume materials such as iron ore, coal, and crude and refined petroleum, suggesting that the volume of trade in physical units may have increased, declining prices may well have offset quantitative gains.

Jan 1, 1988

By Robert J. Evans

The Bureau of Mines is sponsoring a variety of long-term, high-risk research to advance state-of-the-art technology in U.S. underground coal mining. This report reviews the status of many Bureau projects that support fundamental underground coal mining operations; the project areas include cutting coal from the solid (extraction), hauling coal from the face (transport), and activities that sustain daily operations (logistics). Innovative equipment and technology have been developed, with these major objectives: to significantly improve coal mine productivity, to further advance coal recovery and personal safety within the mining industry, and to reduce the time needed to develop longwall panels. The majority of the prototype equipment covered in this report either has undergone or will undergo comprehensive evaluation at Bureau surface test facilities so that performance and reliability can be improved before the equipment is tested and evaluated in a working section underground.

Jan 1, 1988

This report is a proceedings of a briefing recently sponsored by the Bureau of Mines at which Bureau personnel presented findings from their research efforts to improve steelmaking techology currently used in the United States. The papers contained in this report address many areas of concern to the iron and steelmaking industry. Among these are improving arc stability in electric arc furnaces, preheating ferrous scrap to reduce energy consumption, fluorspar substitutes in steel-making, basic steelmaking refractories, corrosion of iron-based materials, improvements in stainless steel acid pickling processes, recycling of stainless steel dusts and other wastes, and use of wastes as a source of zinc for electro/galvanizing.

Jan 1, 1988

By Henry P. Cole

A series of studies are described that identify critical health and safety skills needed by underground coal miners for coping with mine emergencies. First aid and self-rescue and escape were selected as two broad performance domains that include many subordinate skills needed for preventing, recognizing, and coping with mine emergencies. The performance domains and their objectives were used to direct the development of simulation exercises that permit miners to experience mine emergencies in the safety of a training room. The exercises are based upon research with similar simulations for the training of flight crews and medical personnel in information gathering, judgment, and decision making skills. Exercise content is drawn from actual mine accident and disaster case studies. The exercises incorporate recent principles of cognitive psychology and instructional design. Initial studies in annual refresher training classes suggest the exercises are stimulating for miners and their instructors, easy to use and read, sufficiently complex and authentic to challenge experienced miners, and useful devices for both teaching and testing critical problem solving skills required for preventing and minimizing emergencies.

Jan 1, 1988

By Henry P. Cole

A comprehensive review of published research was carried out to identify methods for teaching and assessing critical but nonroutine skills needed for coping with emergency situations. Specific methods for assessing critical skills proficiency in aviation, medicine, organization management, the military, and other industrial/technical workplaces are described. The potential application of these methods for teaching and assessing (1) critical first aid and (2) self-rescue and escape skills to underground coal miners in annual refresher training is explored. Research and development activities that may improve mine health and safety training are suggested. Most of these research and development activities were completed later in the project. This additional work is reported in the project technical report #2 and the final report. The research reported in the present document was completed in 1984 -85. Many of the initial findings reported in this document are updated in the later project final report.

Jan 1, 1988

By Mark S. Sanders

There is a growing awareness among mining professionals that the human factor plays a significant role in safety and productivity. Since the 1960's, the science of human factors, or ergonomics, has been making inroads into the mining industry, and a considerable amount of research has documented human-factor-related mining problems and solutions. This Bureau of Mines report is directed toward summarizing the application of human factors to improving safety, productivity, and the general physical and psychological working conditions of miners. The aim of this report is to familiarize the readers with the role of human factors in the mining industry and the benefits that can accrue by systematically applying available human factors principles and data. The text contains 10 chapters dealing with human, equipment, and environmental factors. Each chapter builds on the previous chapter; therefore, it is recommended that the chapters be read sequentially However, if the report is used as a supplemental text, say in a mining safety course, chapters can be assigned in any order to supplement other readings.

Jan 1, 1988

Mine waste and mine reclamation are topics of major interest to the mining industry, the government and the general public. This publication and its companion volume are the proceedings of a conference held in Pittsburgh, April 19-21, 1988. There were nine sessions (50 papers) that dealt with the geochemistry, hydrology and problems of mine waste and mine water, especially acid mine drainage. These comprise Volume 1. The nine sessions (43 papers) that dealt with reclamation and restoration of disturbed lands, as well as related policy issues, are included in volume 2. Volume 2 also contains the ten papers that pertained to control of subsidence and mine fires at abandoned mines. Poster session presentations are, in general, represented by abstracts; these have been placed in the back of both volumes.

Jan 1, 1988

Mine waste and mine reclamation are topics of major interest to the mining industry, the government and the general public. This publication and its companion volume are the proceedings of a conference held in Pittsburgh, April 19-21, 1988. There were nine sessions (50 papers) that dealt with the geochemistry, hydrology and problems of mine waste and mine water, especially acid mine drainage. These comprise Volume 1. The nine sessions (43 papers) that dealt with reclamation and restoration of disturbed lands, as well as related policy issues, are included in volume 2. Volume 2 also contains the ten papers that pertained to control of subsidence and mine fires at abandoned mines. Poster session presentations are, in general, represented by abstracts; these have been placed in the back of both volumes.

Jan 1, 1988

By Elio Ferreira

This report describes the design, and development work performed to reduce the volume and weight of the miners caplamp battery, as well as a headpiece with a swivel mechanism containing a halogen bulb with two filaments. Work was also conducted in the development of a maintenance free battery. The design concept is based on non-sintered Ni-Cd technology, with an energy density of 22 Wh/lb. The cap lamp system developed has been approved by the Mine Safety and Health Administration (MSHA) and can be manufactured for mine use.

Jan 1, 1988

By C. Larsen, R. A. Walker, A. Voth, C. Daoust

"The 3000 t/d mill at Hernia Gold Mines Inc. was commissioned in March, 1985. By Canadian standards the concentrator is highly automated, however, unlike the retrofit systems in many other plants, the Hernia process control system was installed during plant construction. This paper describes the Hernia control system beginning with system development (justification, architecture, start up, etc.), proceeding to current applications (crushing, grinding, leaching, etc.) and finally discusses some of the short term objectives for system improvement.INTRODUCTIONThe Hernia Gold Mines Inc. operation is located in the Marathon area of Northwestern Ontario. Controlled by Noranda Minerals Inc. (50.1 %), the cost of bringing the mine into production was nearly $300 million. A unique feature of the mine development was the extraordinarily short elapsed time of three years from Noranda's initial involvement to the start of milling operations. Additional background information on this project can be found in the trade literature (e.g. Tinter (1986). Scales (1987).)The Hernia concentrator is designed to process 3000 tpd of ore and commenced operation in March, 1985. Figure 1 provides a general plant flowsheet indicating the major circuits. Typical annual production statistics are included on the figure and these have been extrapolated from the available 1987 year-to-date data. Larsen and Tessier (1986) have previously described the operational aspects of the mill.In a metaphorical sense, the Hernia concentrator is like the traditional bride, ""wearing something old (e.g. the cyanide leach process), something new (e.g. a plant wide digital control system installed during construction), something borrowed (e.g. crushers from Gaspe) and something blue (e.g. the cladding on the surface buildings). While the prospect of fully undressing this bride is of considerable interest, here we choose to focus on something new. In particular, we choose to examine the process control system in some detail since Hernia is one of Canada's more highly autcmated gold mills. The control system is of interest because it has received suostantial credit for maximizing metal production and minimizing operating costs. With reference to the latter, it is worthy of note that Hem lo reports recent operating costs of less than $100 U.S./oz."

Jan 1, 1988

The Australian coal industry has undergone sevenfold growth over the last 30 years and since 1985 has been the world's largest coal exporter. Three quarters of Australia's coal production is exported so its future is dependent on it remaining internationally competitive with other energy sources and other coal exporting countries. Coal is likely to increase its share of the energy market during the nine- ties as oil prices increase, new coal-fired capacity is commissioned and some form of nuclear energy is developed which is of acceptable safety standards to the community for use in the 21st century. Gas may take a part of coal's anticipated market share by the Year 2000. While coal exports will increase from China, Colombia, Indonesia and Venezuela and satisfy some of this additional coal demand Australia will also expand its export production, due to its existing advantages. The United States, Canada, South Africa, Poland and USSR seem unlikely to enjoy the same degrees of expansion and some, particularly Poland and USSR, will decline. Australia will always find it difficult to compete in the more distant markets due to levels of ocean freight, although its high quality coals will tend to partly offset such disadvantage.

Jan 1, 1988

By Daniel E. Walsh, P. D. Rao

"A four-inch compound water cyclone (CWC) was tested to evaluate its gold recovery characteristics when processing -4.8 mm run-or-pit, placer material. Neutron activated placer gold particles (840 to 37 microns) were used as radiotracers (/98Au) in a closed circuit ewe test loop to determine concentrator recovery; a procedure believed unique to this study. The effect on gold recovery of gold size and shape, feed pulp density, feed pressure, vortex finder clearance (VFC), ewe cone type, top-size of the feed solids, presence or absence of heavy minerals in the feed, and the quantity of-37 micron slimes in the feed was investigated in over 300 tests.CWC concentration ratio and the top-size of the underflow solids were both affected by cone type, VFC, and feed pressure. Gold recovery was significantly affected by gold size, gold shape, and concentration ratio. These effects are complex, because significant size-concentration ratio and size-shape interactions exist. Radiotracer techniques showed gold particles had a residence time within the ewe of approximately one second. This study suggests ewe gold recovery is a concentration. This work suggests ewe gold recovery is a function of particle size and shape, and the flow rate through the cyclone. CWC cone ""bed density"" is considered important only as a thin, protective layer, which shields coarser gold particles from the entraining currents and facilitates their movement through the CWC.IntroductionCompound water cyclones (CWC), or automedium cyclones, are enhanced gravity concentrators for the beneficiation for slurries of sand, coal, and ground ore (Fig. 1). They are called compound water cyclones because of the compound slopes of their basal cones (Fig. 2) and are operated to suppress classification phenomena in favour of gravity concentration effects. The compound water cyclone is not a new wet concentrator. It was developed in the late 1950s by Dr. Jan Visman through research sponsored by Canada's Department of Energy, Mines, and Resources. Since that time, it has become a common unit in coal washeries for cleaning fine coal. CWCs and other versions of concentrating cyclones have also shown promise for heavy minerals and precious metals recovery."

Jan 1, 1988

By M. D. Scott

"Highland Valley Copper recently installed a semi-mobile in-pit crushing and conveyor system designed to feed both the Bethlehem and Lornex concentrators with a feed averaging 120000 tonnes per day. The system installed with a rated capacity of 12000 tonnes per hour is the highest capacity hard rock semi-mobile crushing and conveying system currently in existence.The system is designed in a manner that the crushers can be moved easily as the pit is developed in depth with conveyors extending deeper into the pit, and conveyors being moved radially from a surge pile located at the rim of the ultimate pit as the pit increases in size laterally.The system consists of two 6000 tph, 60 by 89 Krupp semimobile crushers feeding two moveable 4500 hp, 60 in. conveyors, 1.25 km long feeding a 7500 tonne live storage surge pile. Two 96 in. belt feeders installed in reclaim tunnels under the pile feed two parallel 4500 hp, 60 in. conveyors, 1.25 km long on a 12 per cent uphill grade to the two existing Lornex plant feed conveyors. A third 96 in. belt feeder, under the pile, feeds a 60 in. conveyor, loading trucks hauling crushed ore to the Bethlehem mill.A description will be given: (1) of the system's design features in which climatic extremes, operating, and maintenance characteristics were of primary importance; (2) of the way the system was constructed from components purchased internationally on an extremely tight construction schedule; and (3) of the way the system has operated during the first few months in operation during which time it demonstrated that it has met various design criteria."

Jan 1, 1988

Jan 1, 1988

By J. R. Welsh, D. J. Palmer, O. M. G. Newman

"The use of calcine for selective zinc precipitation requires specialist knowledge to achieve satisfactory flowsheet design. Calcine from the bed of a fluid roaster is preferred, and factors such as the size distribution of ground calcine, the stoichiometric ratio of the calcine precipitant to the initial dissolved zinc concentration and the moisture content of the resultant filter cake are parameters which require critical attention. Extensive testing in a fully-integrated electrolytic zinc plant pilot plant has demonstrated that properly designed selective zinc precipitation plants using calcine as the precipitant are reliable operating units.The advantages of using calcine instead of limestone for selective zinc precipitation include a decreased cost of reagents, as well as avoiding the formation of by-product gypsum.Process simulation modelling has demonstrated that the use of calcine in this context has widespread application in the design of zinc plants with superior impurity and water balance control characteristics. A particularly powerful approach involves closed circuit washing. In this mode, filtrate from the selective zinc precipitation step is used to wash a zinc plant residue such as jarosite, and the resulting filtrate is returned to the selective zinc precipitation section. IntroductionThe Selective Zinc Precipitation (SZP) Process, developed and patented by the Electrolytic Zinc Company of Australasia Limited (EZ) may be used to achieve simultaneously, water balance and impurity control in an electrolytic zinc plantO,2). Impurities which may be controlled by the SZP process include chlorine, magnesium, manganese, potassium and sodium.In the SZP process, basic zinc sulphate is precipitated from a zinc sulphate solution by either limestone, lime or a compound containing zinc oxide, usually calcined zinc sulphide concentrate (calcine) or alternatively zinc oxide fume .The solids containing basic zinc sulphate are separated, typically, by filtration and returned to the zinc plant circuit as a neutralizing agent. The zinc depleted solution can either be discarded, or used to wash residues, thereby achieving water balance and impurity control (Fig. I)."

Jan 1, 1988

By Steve O. Green

Introduction The US coal mining industry is in the midst of a serious economic crisis. To overcome increased operating costs, operators must take advantage of technological advancements in mining systems and equipment. A relatively new concept available to underground operators is that of extending the cutting depth for continuous mining machines (continuous miners). This system is referred to as deep-cut mining, and may be described as mining cuts to depths greater than the standard 6 m (20 ft). Productivity is increased through the reduction in continuous miner tram time since the machine stays longer in each working face. To successfully implement a deep-cut mining system, three problems must be overcome: Exposing personnel to unsupported roof, methane removal, and controlling respirable dust. Remote control cutting The solution to the unsupported roof problem is remote control. Recent advances in remote operation, especially in radio remote controls, have resulted in what is generally accepted as a safe and reliable tool. By installing remote control on the continuous miner, the operator and helper can now be stationed in a supported area. This allows for improved visibility while cutting coal. With this in mind, the limiting factor now becomes the position of the haulage equipment operator. North River No. 1 uses Joy 21SC shuttle cars and Jeffrey 4110 diesel ramcars. These cars are pulled against the bumper of the continuous miner. Thirteen meters (43 ft) can be cut with the shuttle car and 14 m (45 ft) with the Ramcar before the operator of the car is inby permanent supports. By loading away from the bumper, about 1.5 m (5 ft) can be added, bringing total cut depths up to 14.5 and 15 m (48 and 50 ft), respectively. Methane removal The second problem involves methane removal, and the line curtain-to-face distance. In other words, how to maintain the line curtain to allow sufficient ventilation to remove methane and not expose workers to unsupported roof. The solution, in most cases, is to use a blowing-type ventilation system. Unlike the exhausting system that, to be effective, must be installed within 3 m (10 ft) of the working face, the blowing system can be effective at greater distances from the face. Numerous studies have documented the advantages of a blowing-type ventilation system over an exhausting system. Furthermore, a blowing system can be significantly improved by in¬creasing the velocity of the air delivered without increasing the volume of air. With this greater ventilation efficiency, it is possible to secure ventilation plan approval from the Mine Safety and Health Administration (MSHA) for a greater curtain set-back distance. This eliminates the need for personnel to travel inby permanent supports to extend the face brattice. The distance from the face MSHA will approve, however, is on a mine-by-mine basis. MSHA will evaluate the particular mine's face methane liberation rates, along with the specific proposals regarding face ventilation volumes and velocities. Dust control The third problem is controlling respirable dust. This is actually a result of the solution to the second problem. In the blowing system, while mining on the slab cut, both the continuous miner and haulage units are located on the dusty side of the line curtain (Fig. 1). In the early 1970s, underground operators virtually abandoned this system, in order to comply with the 2 mg/m3 (0.87 gr per cu ft) federal dust standards. The blowing face curtain did offer increased face ventilation efficiency. With that, greater curtain-to-face distances were also

Jan 8, 1987

By Vernon R. Shorter, Wayne N. Clark

Introduction Coal is the US's largest indigenous fossil fuel resource and is used to power 57% of this country's electrical generation (NCA, 1986). Congress, however, is focusing its attention on the acid rain issue and public sentiment is leaning toward further curtailments of SO2, NO, and particulates from utility and industrial coal-burning facilities. The Cool Water plant has proven that integrated-gasification-combined-cycle (IGCC) technology can reliably produce economical electrical power while limiting SO2, NOx, and particulates to a rate of only one-tenth of the federal New Source Performance Standards for coal-fired plants. Process water requirements at Cool Water are 40% less than those of a conventional coal-fired utility plant equipped with flue-gas desulfurization units for stack gas scrubbing, thus reducing waste water treatment requirements (Clark and Shorter, 1985). The IGCC technology employed at Cool Water has now been demonstrated to efficiently convert coal to electricity in an environmentally superior fashion. The Cool Water Coal Gasification Program is an unincorporated California association of six partners whose commitment is proving that the integration of gasification with combined cycle power production (IGCC) is commercially viable and environmentally safe. The 120 MW Cool Water plant began commercial production on June 24, 1984. The Program is operating it for a five-year commercial demonstration period. The Program is about halfway through this period. Much of that which was intended to be proven is now fact. In this mid-term assessment, the authors report that the com-

Jan 2, 1987

By J. D. Patsey, G. T. Lineberry

Introduction A computer program was developed for analyzing drum-type hoists before modifying an existing system or designing a new one. Its use permits the preliminary evaluation of a system before seeking technical assistance from mine hoist designers and manufacturers. The user-friendly program accepts a variety of data and analyzes hoisting systems for any balance state. The program can be used to calculate skip capacity to yield a desired production rate, solve for drum face width, select a permissible wire rope, estimate total horsepower of the hoist plant, and estimate annual power cost. Whether required for a large mining complex or for a relatively small operation, a hoisting system must be carefully designed to ensure the efficient, reliable, and safe flow of material. Because shaft sinking and hoist installation can total between 2.5% and 3% of the cost of opening a deep mine, proper hoist selection is critical. Today's mining engineer has at his disposal the most powerful design and analytical aid ever, the microcomputer. There is, unfortunately, limited software for the study of hoisting systems, unlike that for other materials handling equipment (Manula and Albert, 1980; Prelaz et al., 1964; Bucklen, 1969; Thompson, 1985). HOIST reduces a time-consuming set of calculations to a concise package of interrelated subprograms. A literature review revealed no common-user programs to analyze hoisting systems, although at least four major hoist designers/manufacturers/installers have their own in-house programs. To provide a tool with which the mining engineer could preliminarily analyze a materials hoisting system or could check the calculations of a hoist contractor, a computer program was developed. HOIST was written in BASIC for the IBM-PC for ease of program adaptation and to encourage field use on compatible systems. Details of program development are omitted, since the basic principles of hoisting analyses are relatively straightforward, simple, and readily accepted (Harmon, 1973; Nordberg, n.d.; Adler, 1957). Program features, intended usage, and benefits of the computerized solution are emphasized over theory development and mathematical rigor. Background The mine hoist system that is selected and installed at a mine is the "lifeline" of that mine, with installations lasting 20 years or more. Thorough study is warranted to ensure that productivity demands are met at a minimum cost per ton. The increased cost of a large, powerful, high-speed hoist must be offset by increased production to justify its selection. To optimize this tradeoff, an extensive hoisting analysis should be performed. The analyses to properly size the skip (or cage), the drum, and the hoist drive are conducive to computerization, permitting rapid evaluation of changeable operating and design parameters, such as velocity, acceleration, state of balance, and productivity demand. The program is particularly useful in conducting sensitivity trials, such as investigation into the effect of change of productivity on skip capacity and on horsepower of the hoist drive. HOIST is currently limited to the study of drum-type hoists with cylindrical drum(s). However, only minor changes to the program would permit analysis of friction hoists and conical drum configurations. Model development and testing The program is based on accepted equations and physical relationships. Examples of manual calculations formed the basis for decision points and program branching. Data is input in the order that it would be needed if the problems were solved manually. The choices are arranged likewise. HOIST was developed in sections, with manual solutions performed to check program logic. The testing became more rigorous as sections were completed. Output from one section becomes input for following sections, as appropriate. The simplified flow diagram of HOIST is given in Fig. 1.

Jan 2, 1987

By Forsén. O.

In this ?paper practical solidification of anodes containing nickel, arsenic, antimony and bismuth is compared with the equilibrium? diagrams and kinetic ?factors. In order to clarify the distribution of the impurity elements in the anode the structures were studied after the solidification and also after the electrolysis of anodes. This examination was carried out with optical microscope, scanning electron microscope and electrochemical measurements. All the nickel is remaining metallic in the copper matrix during the solidification and therefore nickel is dissolved in the electrolysis at all oxygen contents, when the nickel content is 0.25 wt-% or less in the anode. The practical .solidification mechanism of the anodes, when the nickel content exceeds 0.25 wt-%, proceeds by the crystallization of nickel oxides. In oxygen containing copper anodes nickel oxide is verified to crystallize together with antimony in certain conditions and to form a micaceous compound (3Cu2O?4NiO?Sb2O5), which may build up a very harmful floating slime in the electrolyte. Arsenic is strongly enriched along the phase boundaries in oxygen free copper anodes. An intermetallic compound Cu3As is formed when the amount of arsenic in the anode. exceeds 0.7 wt-%. This compound is more noble than the copper matrix. This means 'that a selective dissolution of copper-arsenic compounds takes place. The copper matrix dissolves more strongly than the grain boundaries. The solidification structures of oxygen free bismuth containing copper anodes show clearly the influence of bismuth. Thin bismuth films which are less .noble than the metallic copper matrix, are formed during the solid1ficatton process. As a result of this the?grain boundaries are dissolved faster than the copper matrix.

Jan 1, 1987