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By Richard S. Della Valle

Sandstone and shale samples from the Morrison (Late Jurassic) and Dakota formations (Cretaceous) from northwestern New Mexico have been analyzed for the major elements Na, K, Fe and the trace elements Sc, Cr, Co, Rb, Sb, Cs, Ba, Hf, Ta, Th, iJ and the rare earth elements (REE) in whole rock and clay sized fractions by instrumental and delayed neutron activation analysis. The clay sized fraction clearly shows enrichment patterns and halo effects ; whereas, the whole rock fraction does not. Important elemental dispersion halos associated with uranium in sedimentary environments include the REE, Hf, and Sb. The distribution of these halos are due to a combination of complexation, chelation and the orignal paleoenvironments.

Jan 1, 1984

By Jr. Kirschner

An abandoned waste impoundment located within a portion of the Kellogg, Idaho Superfund site constitutes a field research area for studying the feasibility of recovering heavy metals in-situ from unsaturated mine and mill wastes. A prototype in-situ leaching cell has been evaluated using liquid-phase tracer tests and other hydro-geologic tests prior to introducing a lixiviant. The results of the tests suggest that: (1) the cell can be operated excursion-free with a low-density lixiviant at an injection/withdrawal rate of approximately 0.32 l/s; and (2) each hydro-geologic unit is highly heterogeneous at the different scales studied.

Jan 1, 1993

By William Harrison, Robert H. Trent

GENERAL DESCRIPTION History The most striking feature of mining in the United States has been the infrequent use of longwall systems. This system, which accounts for the majority of coal production in Europe, Japan, and other countries, is only recently growing out of its infancy in the mining of normal coal seams and is still untried in the mining of thick coal seams in the US. Its use in the mining of metal and nonmetal ore bodies has been virtually ig¬nored, except for isolated instances in trona, copper, and uranium. Longwall mining is believed to have originated in Shropshire, England, towards the end of the 17th cen¬tury (Laird, 1973). Although the method used would be considered primitive by today's standards, many of the basic concepts have remained unchanged. Longwall mining of coal in the US was first introduced before the turn of the century, but it never gained acceptance as it did in Europe. Historically, longwalling was a cyclic method where a single cut of coal was removed from the face on the producing shift each day, and the work of building stone packs in the gob and manually moving roof support was completed on the off shifts. Due to the amount of dead work, productivity was extremely low. In Europe, however, longwall methods were required despite the high costs involved, because only by this method could coal under heavy depth be mined with any reasonable degree of recovery. Reserves of coal lying under shallow cover, and therefore minable by room¬and-pillar methods, were long ago inadequate to supply most of Europe's coal requirements. In the US coal min¬ing has historically proceeded laterally with the new mines in virgin areas to replace old mines; in Great Britain, Germany, Japan, and many other countries, mining must proceed downward to greater depths. The depth of cover for most coal operations in the US is shallow, i.e., 61 to 305 m (200 to 1000 ft). This, combined with large reserves, has made room-and-pillar methods almost universally applicable. However, longwall systems were tried around the turn of the century. Whenever used, it was frequently noted that the opera¬tion was under the direction of men with foreign ex¬perience and was tried under ideal conditions. Some of the mines that were using longwall or had tried longwall prior to 1910 were the Radiant mine, CO; Vinton Coal Co., PA; Cambria Steel Co., Johnstown, PA; Grundy County and Spring Valley, IL; and unnamed mines in Washington, West Virginia, Kentucky, Iowa, and Kansas. As late as 1961, there was one circular longwall in operation at Centerville, IA. The first modern-day op¬eration to take advantage of European technology and longwall methods was Kaiser Steel Corp. at its Sunnyside mine near Price, UT. Due to deep cover and extremely poor roof conditions, combined with a need for in¬creased production, Kaiser management decided a new method was required and turned to longwall in 1961. The first longwall consisted of an Anderson Mavor shearer loader, British Jeffrey-Diamond conveying equip¬ment, and Dowty roof supports with a capacity made up of two and three 27-t (30-st) capacity props. After nor¬mal start-up problems, this unit averaged over 454 t (500 st) per shift (White and Palacios, 1976). During and after World War II, technology in hy¬draulics and controls had advanced to the point that self-advancing supports and hydraulic props were being developed. In 1960 only I % of West German produc¬tion was from mechanized longwall faces. This in¬creased to 37% in 1970 and 63% in 1973 (Kohlgruber, 1974). In 1976 there were 246 coal mines operating in the United Kingdom. Although this is only 50% of those operating ten years ago, the production has increased 42%, mainly through improvements in longwall equipment and methods (Hunter, 1976). In France and other European countries, the devel¬opment of longwall mechanization has been similar in seams up to 2.44 m (8 ft) thick. In seams that exceed 9.14 m (30 ft), a variety of longwall caving has been developed for coal seams with dips of 0 to 1.6 rad (0 to 90°). Those with the greatest success will be discussed later. As noted, the development of longwall mining to its present state of the art has mainly taken place since World War II with substantial gains in the last ten years. Mechanized longwall has been the result of several re¬lated major innovations (Jackson, 1975) 1) Development of the flexible armored face con¬veyor which can be installed along the face and moved forward without disassembly. 2) Development of face machines such as single and double drum shearer and coal plows which operate in conjunction with the armored conveyors. 3) Development of self-advancing hydraulic roof supports which now include chocks, chock shields, and shields. 4) Reliance of caving of the immediate roof based on proper planning and development. 5) Use of pneumatic slowing to enable extraction below overbuilt areas. The most recent developments in the mining of coal by longwall in the US include the introduction of shield supports at Kaiser's York Canyon mine in New Mexico, single-entry longwall development at Kaiser's Sunnyside mine, and Mid-Continent's advancing longwall system in Colorado. Metal and nonmetal longwall systems in the US have included the mining of copper at White Pine, MI; uranium in Utah and New Mexico, and trona in Wyoming.

Jan 1, 1982

By Robert J. Henning

The term olivine was first used in 1790 by J. Werner, and the corresponding mineral was so named because of its olive-green color (Hunter, 1941). Olivine is the principal component of the rock known as dunite. While by classic definition dunite is composed of 90% or more olivine, commercial use of these terms has resulted in more specific definitions. Commercially, the term olivine is used to designate a material that consists of 85% or more forsterite and contains 45 to 50% MgO, 39 to 42% SiO2, 5 to 8% Fe2O3, and has an ignition loss (LOI) of 1 to 2%. The term dunite designates a rock that contains 36 to 45% MgO, 36 to 39% SiO2, and has an ignition loss of as much as 10% (Teague, 1983). GEOLOGY Olivine is found in basic igneous and basic metamorphic rocks whose age varies from pre-Ordovician to Tertiary. Economic deposits are of magmatic origin and are restricted to the dunite variety of the peridotite group of ultrabasic igneous rocks. Olivine also occurs in basic igneous rocks such as gabbro, basalt, and diabase and more rarely as an accessory mineral in granite and metamorphosed crystalline limestones. Mineralogy The term olivine refers to a group of orthosilicate minerals in isomorphous series with magnesium-rich forsterite (Mg2Si04) as one end member and iron-rich fayalite (Fe,SiO,) as the other. In most olivines the ratio of magnesium to iron varies from 16: 1 to 2: 1. Commercial olivine deposits contain a mixture of forsterite and fayalite with the fayalite content restricted to less than 15% (Reed, 1959; Teague, 1983). Accessory constituents may include primary minerals such as ilmenite, magnetite, diopside, chromite, and garnet and secondary minerals such as chlorite, serpentine, talc, and vermiculite as alteration products. Chemical and Physical Properties The chemical composition of olivine can be expressed as either (Mg, Fe), SiO, or 2(Mg, Fe)O.SiO,. Table 1 presents chemical analyses for some commercial olivines. The physical properties of olivine are shown in Table 2. Distribution of Major Deposits Commercial olivine and dunite deposits are found in Norway, Japan, Spain, India, Italy, the United States, Sweden, Austria, Pakistan, and Mexico. Noncommercial deposits have been reported in New Zealand, Zimbabwe, South Africa, New Caledonia, Greece, Brazil, and Canada (Teague, 1983). The present markets for olivine are characterized by low unit value, high volume, and high sensitivity to freight costs, so few deposits are commercially viable. Literature from the USSR indicates that considerable research on olivine refractories is being done. (Afansa'ev, 1988), lending credibility to the conjecture that commercial deposits are being mined there. In eastern Canada synthetic olivine is being produced by calcining chrysotile asbestos mine tailings. In the United States numerous lenses of olivine extend in a belt from northeast Georgia northeastward across western North Carolina. Total reserves in North Carolina and Georgia are estimated at between 125 and 200 Mt. The largest US deposit is Twin Sisters Mountain, located in Whatcom and Skagit Counties in the state of Washington. This deposit, which has an outcrop area of 93 km2 and a relief of about 1 525 m. is estimated to contain 1 800 Mt of fresh, unaltered olivine (Teague, 1983). In addition, the US Bureau of Mines reports reserves of 50 Mt on Cypress Island in the state of Washington, and the literature reports eight complexes in southeastern Alaska, some containing cores of olivine as large as 1.6 km in diameter (Taylor, Jr., 1967). The world's largest deposit of olivine occurs in the Aaheim area of Norway, where reserves are estimated at a 2 000 Mt. Several other Norwegian deposits contain as much as 5 Mt each. In Japan the production of ultrabasic rocks is currently about 6 Mtpy, but the bulk of this output is serpentinite. Olivineldunite accounts for only 17% of this production. The major olivine deposit in Japan is located at Horoman Hill on the northern island of Hokkaido. Reserves at this deposit are estimated at 100 Mt (Anon., 1990). Spain is one of the largest producers of dunite. Reserves in the La Coruna District in northwestern Spain are estimated at 100 Mt. India, also a major dunite producer, has a large deposit at Salem in Tamil Nadu. In Italy olivine/dunite is mined from a deposit near Turin. In Sweden the largest deposit is at Arutats and is reported to be comparable in size to the Twin Sisters deposit in the United States. At present the only production in Sweden is from a deposit 30 km south of the town of Gallivare. Reserves at this deposit are reported to be between 1 and 2 Mt. Other significant deposits are: 1) in Austria at St. Stefan near Leoben, 2) in the Swat District of the North West Frontier Province in Pakistan, and 3) in Mexico at Cuidad Victoria in Tamaulipas (Anon., 1990).

Jan 1, 1994

By Zhiguo Chang, QINGXIANG CAI, Ebelia Manda, IZHAR MITHAL JISKANI, XIANG LU, Wei Zhou, Saleem Raza Chalgri

The concept of mine safety is highlighted in the literature of sustainable mining but not extensively discussed. This study analyzes various aspects of underground and surface mine safety and emphasizes its importance in the context of sustainable mining. More specifically, this research attempts to find the relationship between mine hazards and demographic characteristics, examine and compare the perceptual difference among miners, and determine the impact of mine hazards on workplace safety and safety climate. Descriptive analysis, chi-square test, independent samples t test, and linear regression modeling were conducted to achieve study objectives. Results confirmed that mine hazards were significantly associated with age and experience. Miners perceived lower levels of management safety practices, followed by supervisor safety, coworker safety, and job safety. The analysis showed that underground miners reported lower safety scores than surface miners. There was a statistically significant difference between miners’ perception of safety climate (p < 0.05). The results showed that the higher prevalence of mine hazards predicts poor workplace safety and a low safety climate. The regression models revealed that mine hazards have a significant effect on workplace safety (p < 0.05) and safety climate (p < 0.05). In conclusion, the distinctive model of mine safety presented here contributes to the monitoring and design of comprehensive safety interventions and helps to better understand how certain factors interact on multiple levels to influence the overall safety of the industry. In this study, some suggestions are put forward to provide directions to develop a sustainable mine safety system.

Mar 27, 2020

By Xingang Wang

Spontaneous combustion is one of the most important safety issues in the global coal industry. It is considered to be a trigger for explosions in underground mines, especially for gassy mines. This thermal event is not easily detectable in the gob and sealed area. It is also a tough job to find the most likely hot point accurately. Admittedly, determination of the propensity for spontaneous combustion before mining activity should be a necessary step in the design of a mine and ventilation plan. However, due to the complexity of the chemical and physical properties of coal, spontaneous combustion has not been fully understood. According to a proximate analysis of coal, it is believed that sulfur and volatile matter in coal are the main intrinsic factors that cause the self-heating of coal. Their oxidation at lower temperatures than that of fixed carbon to initiate coal?s self-heating should be quantified. This study aims to improve the previous mathematical model developed by the authors for studying a coal?s propensity for spontaneous combustion. It enhances the model?s ability to consider the effects of sulfur, volatile matter and moisture content in the coal ? three important factors affecting a coal?s self-heating process. Based on the law of energy conservation, heat release rates for pyrite oxidation and moisture condensation are built into the model. Finally, the simulation results in terms of time versus temperature are calibrated with adiabatic testing data extracted from the literature for pyrite oxidation and moisture condensation, respectively. From the modeling results, it is found that the higher the pyrite content the coal contains and the more moisture that condenses in an environment with high relative humidity and initial temperature, the higher the potential for spontaneous combustion.

Jan 1, 2014

By Jerry Dolph

In September 1855, 55-year-old Noah Spencer Kellogg and his $3 jackass named Bill discovered what was known at the time as a “blow out” of high-grade lead and silver ore. The deposit was located on the side of a North Idaho mountain high above the South Fork of the Coeur d’Alene River. The ore was later assayed at 41,141 g/t (1,200 oz/st) silver. Kellogg named his discovery the Bunker Hill Lode, after the June 17, 1775 Revolutionary War battle of Bunker Hill. A thriving pioneer settlement sprang into existence around the resulting mine’s workings and was eventually— and appropriately — named Kellogg. The peak rising hundreds of feet above the mine’s adit was named “Jack-ass Peak” after Noah Kellogg’s hairy companion.

Jan 1, 1996

By P. A. Plunkert, D. E. Morse, L. McCartan, S. F. Sibley

Following the recession of 2001, restrained consumer spending, declines in domestic manufacturing and industrial output, and increased unemployment led to a lack-luster year in the domestic economy. In 2002, the U.S. real gross domestic product (GPD) grew only 2.4%. Significant production declines in the U.S. metals industry were registered by copper, lead and zinc producers. Steel producers, despite a slight improvement in shipments, continued to face strong foreign competition, higher energy costs and lower prices for their products. Homebuilding and other domestic construction sectors— major consumers of nonmetallic mineral products such as cement, brick, glass and stone — remained strong enough to help raise the output of industrial mineral materials slightly above 2001 levels. A strong U.S. dollar relative to other national currencies continued to weaken the competitive stance of U.S. metal and non-metal mineral materials companies alike against foreign producers in markets at home and abroad.

Jan 1, 2003

By D. J. Tooker

For the next few minutes, I will be discussing a product and category that many people laughed at for years. The product is cat box filiers or commonly referred to by the brand name KITTY LITTER. This product was introduced in 1947 by Ed Lowe using the name KITTY LITTER. From 1947 to 1964 the product was sold mainly through pet shops. Starting in 1964, the grocery trade began to carry cat litters. From that point, the cate gory began a solid growth trend. Particularly in the &apos;7O&apos;s, cat litter has experienced the same kind of explosive growth that has characterized the entire pet market. For example, in the twelve months ending 9/21/79, cat litter unit volume grew by 15% versus the previous twelve months. The basis for this explosive growth is easy to comprehend. The cat population itself is rapidly expanding, reflecting the changing life- styles of Americans. As famiiies grow smaller, there is room for a pet. As apartment and con dominim living shrinks living space, a cat fills the human need for animal companionship more efficiently. Table I illustrates current cat litter market factors and projects major trends into the future to conclude that the cat litter market will equal $205MM in 1985. With this dynamic growth defined, it was imperative that a company such as Lowe&apos;s that was totally devoted to the commodity-priced products, evaluate the opportunities for added- value product differentiation. This process was started approximately four years ago with a search for new cat litter products and other new product opportunities.

Jan 1, 1980

By M. Ramachandran, R. G. Reddy

"A direct route for the reduction of magnesium oxide to magnesium using thermal plasma processing, with methane as the reducing gas, has been systematically evaluated. A feasibility study of the reduction reaction has been performed on the MgO-CH4 system at different methane concentrations and temperatures. The effects of changes in the key process parameters, such as the oxide-to-methane ratio and plasma power, on the yield of magnesium have been systematically evaluated. A maximum yield of about 61 mol% Mg was obtained using power of 20.0 kW and a molar ratio of MgO:CH4=1:1. Phase, morphological, elemental and binding energy analyses were performed on the product powders to understand the reduction reaction. Surface oxidation was observed in smaller magnesium particles in all the experiments, while the in-situ sintering of magnesium rods was observed at a molar ratio of MgO:CH4=1:1.5. Magnesium carbide (Mg2C3) was observed in the product, and its mechanism of formation is proposed using phase equilibrium data and a predominance diagram.IntroductionMagnesium has an excellent combination of low density and high strength. These properties have increased worldwide demand for and use of magnesium. Two major processes are used in the commercial synthesis of magnesium metal. The first method is electrolytic reduction and the second is thermal reduction using Pidgeon process. These processes can be classified as traditional techniques, but there are numerous emerging technologies that aim at reducing the production cost of Mg, its environmental impact and energy consumption. Thermal plasma processing is one emerging technique that has great potential in all the abovementioned key areas of magnesium production.Traditional reduction techniques. Two major reduction techniques, namely electrolytic and thermal reduction, have been used in the commercial production of magnesium. Electrolytic reduction is typically carried out in electrolytic cells from magnesium chloride (obtained from seawater or well and lake brines) (Tripp, 2009). The following simplified reaction shows the reduction of magnesium chloride to liquid magnesium and chlorine gas:"

Jan 1, 2015

By Eugene Honeycutt, David Gallagher, R. E. Melley, Nick Madison

Drummond Co. Inc.&apos;s Shoal Creek Mine slope conveyor is the highest lift, highest horsepower, highest tension conveyor system in North America. The system has a capacity of 4950 t/h (5500 tph), a vertical lift of 360 m (1180 ft) and a total connected power of 6000 kw (8000 hp). The mine will include 2 longwall machines and 5 to 7 development sections. Annual raw production will approach 9 million tly (10 million tpy). This paper describes the early investigation of system capacity, haulage system options, and the final selection of a single flight belt conveyor. It will review the basic system de- sign and equipment selected. Also included will be some highlights of the installation of the conveyor system.

Jan 1, 1996

By J. J. Schwoebel, M. J. Mavor

Rapid coal extraction techniques in gassy mines may strain a ventilation system if a degasification approach is not utilized. Design of mine ventilation systems requires estimates of gas emission rates from unmined coal into the existing mine workings. A degasification system for a specific property can be properly engineered to improve mining economics if the proper geologic and reservoir information is collected. This paper describes methods to determine the degasification rates for horizontal boreholes and vertical (stimulated and unstimulated) wells and the rate of gas emissions into the mine workings. The methodology is demonstrated by a specific example. Horizontal boreholes drilled in advance of mining are demonstrated to be the most effective means of coal seam degasification and reduction of gas emissions into mine workings. The significance of the paper is that few published methods for these estimates are available

Jan 1, 1991

By D. F. Boyd

On April 10, 1958 a new 7500 long ton/day iron ore beneficiation plant went on stream producing an average of 3000 long-tons of high quality concentrate a day. Plant operates on two, 12-hour shifts is six days per week, The new mill end crust ink plant were built adjacent to the company&apos;s open pit dining operate on at Bomi Hills, Liberia. The mall is essentially a gravity concentrator employing crushing, and grinding to liberate the mineral values, followed by concentration in Humphreys spirals. The cleaner spiral tailings are re-ground and tabled to recover additional iron values. Ire addition to. this mills the company operates a crushing and screening plant for the high grade direct shipping ores

Jan 1, 1962

By J. M. Van Langen

In 1965 Hoogovens was looking for additional capacity for burden preparation in the order of 2,5 to 3 million metric tons per annum of some kind of optimal blast furnace ore feed. In principle four solutions offered them-selves for further investigation: 1. purchase of screened ore and/or run of mine ores with the provision of a corresponding ore screening capacity on the blast furnace site; 2. manufacture of sinter; 3. purchase of pellets; 4. manufacture of pellets. After studying the technological, technical, economical and commercial factors Hoogovens decided for the last mentioned possibility. Before taking this decision not only a great number of different mixtures of iron ore were tested, but during a long period in one of the big blast furnaces a number of tests were also executed with purchased pellets from South and North America. It was found, that using 50% acid pellets with 40% basic sinter a coke rate saving of 25 kg per ton hot metal (50 lbs/net THM) and a production gain of 15% could be obtained as compared with a full sinter practice. With some pellets it became clear, that due to properties, commonly referred to as swelling, we got very poor furnace performances; so in studying the production of pellets, pellet quality should be regarded as the most important aspect of the problem.

Jan 1, 1972

By Joseph O. Cook

I know this is, at best, a frustrating period for the coal mining industry. About 20,000 miners have been laid off, mostly in the Appalachian and mid-western areas, and several mines are working less than 5 days a week; however, the industry is experiencing modern growth and, at least, there is the potential for future growth. The coal industry is probably only operating at about 80 percent of its present capacity, and it is certainly capable of helping this country solve its energy problems. Growth, as a rule, does not come easy, and growth in the coal industry is no exception to this rule. Many formidable challenges have to be overcome. As we all know, mining relies very heavily on the earth sciences, which have advanced significantly in the past few years, but we are always working in a changing environment which in most cases is a hostile environment. Large quantities of material are quickly extracted and rapidly moved in, generally speaking, a very confined area. The very nature of the mining business directly and constantly impacts our environment during this period in which the Nation and the world has become increasingly smaller and more concerned about protecting our environment. In addition, growth brings about an expanding work force which is increasingly younger and less experienced.

Jan 1, 1980

By W. H. Stahl

The continuous vacuum filtration is the solid-liquid separation process that is nowadays most frequently used in the beneficiation industry all over the world. After a development time of several decades, the various filter types such as drum filter, disk filter, plate filter and belt filter can be consideres as a sound functional design ensuring a trouble-free operation. Nevertheless, the vacuum filtration does no longer meet the present and future technological requirements. The moisture content of filter cakes is too high. Their thermal secondary drying is too expensive (coal, ores) and may bring about undesirable material changes and the filter cake conditioning with water-binding substances for dumping purposes is too costly.

Jan 1, 1983

There are bound to be changes with age, so I should not have been surprised or disappointed when what I had considered as high ad- ventures were much fewer and more widely scattered in the last 20 years of my long and active business life. But such adventures came until I was past 80 years of age and no one could expect more than this. Frequent visits to mines in this country and Canada and directorships in Bralorne and its subsidiaries, Homestake Mining Co., Bradley Mining Co., and the Bunker Hill Co.; and Copper Range Co. and its great new White Pine mine in Michigan, lasted far beyond the usual retirement age. The least happy part of my last two decades of active life was the death or sickness of many of my old friends. Hubert d&apos;Autremont, whose friendship no one could replace, died suddenly in 1946. Henry Carlisle and Temple Bridgeman, for many years office associates, had heart attacks that cut down their activities far too soon. Many other less intimate friends died or became ill, but I knew that with advancing years such losses were inevitable. These memoirs would be endless if they covered all of the unusual work and associations I found in the last 20 years. So I must confine the rest of my recollections to expeditions that would have thrilled any engineer at any time. Masaro Mine, Mindanao, Philippines The first of the four "high adventures" came late in 1949, when I was 65 years old. For over a month I had been discussing reported rich lead-silver-copper properties in the Philippines with Thayer Lindsley and other officers of Panaminas. A competent and agreeable "Elderly" (not as old as I was) engineer named Ward Williams had talked with Thayer about high grade mines in a remote part of the

Jan 1, 1976

By Felicia F. Peng

To minimize SO2 emission and the particulate problem during combustion of high sulfur coal fines is to agglomerate these fines in the presence of limestone. At subsequent combustion process, the sulfur in coal is oxidized and reacts with calcined limestone to form calcium sulfate in ash, while the base carbon is converted to clean energy. Seventy percent of sulfur retention can be achieved at Ca/S mole ratio of 3 at a temperature range of 500-400°C. The sulfur fixation in agglomerates involves the complex mass transfer and multiple successive reactions. The rate expressions have been developed to describe the progress of sulfur fixation in the agglomerates during combustion.

Jan 1, 1985

Industry and regulatory agencies have requested guidance on safe blasting near transmission pipelines. The US Bureau of Mines (USBM) and Amax Coal Co. studied surface coal mine overburden blasting near four steel and one PVC pipeline of 15 to 51 cm-diam (6-20 in.-diam), monitoring vibration, strain and pressure. Unlike tests of small blasts simulating construction, these were up to 1 t (2200lbs) per delay in 31-cm (12-in.) blastholes. Worst-case comparisons showed that 12.7 cm/sec (5 in./s) blasting vibrations produced strains about one fourth that of pressurization and 10% to 18% of the ultimate tensile strength. No failures occurred from blasting as close as 15 m (50 ft), which produced vibrations over 60 cm/sec (24 in./s).

Jan 1, 1995

By D. J. MacKinnon

Smooth, compact, dendrite-free, 24-h zinc deposits have been electrowon from zinc chloride electrolyte using a diaphragm cell. The cell consisted of sealed anode compartment con- taining DSA anodes which were separated from an open cathode compartment by Dynel cloth membranes. Fresh electrolyte was fed to the cathode compartment where zinc deposition onto an aluminum cathode was aided by air-sparging. The catholyte passed through the diaphragm into the anode compartment from which chlorine gas and spent anolyte were withdram.

Jan 1, 1980