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By V. P. Petrov

There is a great number of asbestos deposits in the USSR. Some of them are quite large ones. The main deposits of chrysotile asbestos can be seen in the sketch map (fig. 1). Bazhenovo deposit situated in Sverdlovsk region is the largest of them. It is on mining operations since year 1889. Systematical studies of asbestos deposits were begun from the first years of Soviet Government and connected with the names of K.E. Tarasov, P. M. Tatarinov, B. J. Merenkov, N.D. Sobolev, F. V. Syromjatnikov, V. N. Lodochnikov, V.P. Petrov, V.P. Eremeev, L.A. Sokolova, V. R. Artemov, V.F. Dybkov and many others. This investigations served the USSR to be one of the most important producers of asbestos in the world. In the limits of the report a characteristic of the main asbestos deposits of the USSR may be done in general outline, from the point of view of their genesis, and in order to show their common features and differences that must be taken into account for forecasting, exploration, and mining of asbestos. All chrysotile asbestos deposits of the USSR were formed of magnesium rock as a result of comparatively lower-grade temperature hydrothermal alteration and free crystallization of fibrous chrysotile in open cavities that served as catalyst As a matter of fact an important mineral for industry is not chrysotile in general, a widely distributed rock-forming mineral, but a long fibrous and mainly vein variety of chrysotile. It must serve for geologists as an important prospecting criteria. A geologist should search for the mineral not only places of possible chrysotile generations, but places where asbestos may be crystallized in its long fibers that could be fiberized well. The Soviet geologists distinguish two groups of chrysotile-asbestos deposits: (1) related to ultrabasic rocks and (2) related to sedimentary dolomite terranes, taking into account what the maternal rock was affected by hydrothermal solutions. The largest deposits related to ultrabasite. The largest deposits in dolomite are small ones but their asbestos contains almost no iron. So much asbestos is a better filler into insulating plastics. There is a few types of asbestos deposits in the limits of the ultrabasic group. The largest of them is a Bazhenovo type which the deposits of Urals are attributed, and Bazhenovo deposits is the first instance. The Bazhenovo type is characterized by the most complete zonality in disposition of various kinds of asbestization. This type of deposits is practically the only one to be in working now in the USSR.

Jan 1, 1978

By J. A. Herbst, Z. Rogovin

In order to develop more accurate procedures for scale-up and design of semi-autogenous grinding mills through detailed mathematical models, a better understanding of the charge motion and rocklball segregation is needed. To achieve this a 0.61 m (2.0 ft) diam by 0.305m (1 .0ft) length plexiglas mill was constructed as a scale model of a commercial SAG mill. Rock motion in the rotating mill was simulated using various sizes of ceramic balls. Quantitative measurements of dynamic angle of repose, water and slurry motion, holdup and size segregation of the charge were taken. In addition, a video presentation (available to the public) was prepared to elucidate charge and water motion at various mill speeds, charge volumes, rocksize distribution, and flow rates.

Jan 1, 1990

By Terry A. Ring

Sand bed filters are used to remove large and small particles from liquid streams. The large particles are removed by the straining action of the filter bed and the small particles are removed by particle deposition on the surface of the bed particles. Particle deposition, while being essential for the filtering action of colloidal particles, is not the only process that occurs in the filter bed. Other processes that occur are (1) the substrate becomes filled with particles limiting further deposition, and (2) some deposited particles are resuspended. The sum total of all these processes determine the performance of a filter bed.

Jan 1, 1982

By Christopher J. Farrow

This paper describes the grinding circuits installed at two remote sites in northern Canada. One is Cominco's Polaris Project at Little Cornwallis Island; a barge-mounted lead/zinc concentrator. The other is Echo Bay Mines' Lupin Project at Contwoyto Lake, 400 km northeast of Yellowknife, a gold mine, all components of which had to be flown to the site. Logistics and considerations of operating and maintenance presented challenges which were met by innovative design. The evolution of the grinding circuits is discussed. Both plants are operating at design throughput.

Jan 1, 1983

By Larissa Koroznikova, Steve Durkin, Patrick Bouwmeester, Michael Tuck

 This research project explored the viability of a new mining technology — thermal fragmentation — in narrow-vein mining. Thermal fragmentation technology uses a flame jet to produce extreme heat that spalls the surrounding rock to a strategically located drill hole, as an alternative to traditional blasting. This paper creates a net present value (NPV) model of a mining method using thermal fragmentation as well as one of an existing method used for narrow-vein mining. Comparisons and evaluations were made regarding the feasibility of the new technology. It was found that while overall costs for thermal fragmentation were relatively high, reductions in wages, haulage and processing costs as well as increased productivity and ore recovery meant that the new method would improve the financial performance of any operation.

By J. Andres

"Freeport-McMoRan’s Sierrita operations refines molybdenum disulfide in a ferric chloride leach to remove impurities. To understand bottlenecks in the leach process and the true capacity of the leach system, a cross-functional team was established to look at theoretical models, kinetics of the leaching process, equipment limitations and operational strategies. A series of in-plant tests were run which resulted in a road map for improved throughput. INTRODUCTION Molybdenum, a vital component in the steel industry, is often found in nature as molybdenum disulfide (MoS2). Molybdenum disulfide deposits can exist as standalone components in an ore body, or can also be found within copper porphyry nodes. Processing for these copper/molybdenum porphyry ore bodies involves a first stage of flotation to produce a bulk concentrate before separation of the copper and molybdenum concentrates in a second stage of flotation. In this second stage of flotation, a reagent is added to suppress the copper particles, while allowing the molybdenum disulfide particles to remain hydrophobic and continue to float. This separation is very good at keeping the molybdenum out of the copper concentrate; however a portion of the copper continues to float through the circuit. As a result, there is typically some amount of copper in the final molybdenum concentrate. This copper must be removed in order for the molybdenum disulfide product to meet product quality specifications. Once the raw molybdenum disulfide product has been made, a separate process must be applied to remove any copper, lead, or other impurities remaining in the concentrate. This process usually involves the selective leaching of impurities out of the bulk solid. Gupta mentions three specific types of leaching agents, sodium cyanide, ferric chloride, and hydrochloric acid for the removal of sulfide impurities. Sodium cyanide is useful for the removal of copper compounds such as bornite, covellite, and chalcocite.1 Sodium cyanide solution dissolves these copper compounds, and the remaining molybdenum solids are filtered to produce a pure molybdenum concentrate. Ferric chloride works similar to that of sodium cyanide, but is particularly efficient in removing chalcopyrite and galena compounds. These compounds are easily chlorinated at elevated temperatures, producing copper chloride and lead chloride, through the reactions presented below:"

Jan 1, 2015

By Christophe Bragard, Rebecca Reeve

The Regional Connector Transit Corridor (RCTC) Project is a 1.9-mile-long metro light-rail extension project that traverses the historical core of downtown Los Angeles, California. This project aims to improve mobility throughout downtown LA with fewer transfers for riders. It is designed to connect two existing rail lines for a more seamless travel. The project consists of twin bore tunnels, three new stations, and is scheduled to be completed in 2022. The design-build contract was awarded to the Regional Connector Constructors (RCC) in 2014, a joint venture of Skanska and Traylor Bros, Inc. with Hatch Mott MacDonald as the designer. One of the challenging aspects of the project was the construction of a crossover cavern in a narrow public right-of-way surrounded by historical structures. RCC used Sequential Excavation Method (SEM) to construct the crossover cavern measuring 287 ft long by 58 ft wide by 36 ft tall. The initial lining of the cavern featured a 12 in. fiber reinforced shotcrete lining. The initial lining was separated from the final lining by a hydrocarbon resistant membrane, as specified by the standard requirements of Metro. The cavern features a cast-in-place final lining with a thickness of 5 ft 9 inches in the invert and 18 inches in the crown and walls. The structure also features a nonload bearing plenum slab and interior walls for ventilation.

Jun 13, 2021

By Brad Grothen, Lok Home

The choice of TBM type is never easy, but it becomes especially challenging when faced with a hard rock tunnel with expected high water flows and pressure. Slurry Shield tunneling has a long history of being used in these conditions to minimize the risk, though this method has brought with it other risks along with cost considerations. At recent projects around the world, another method has been proven to effectively manage these project risks without utilizing Slurry Shield tunneling: Shielded, NonContinuous Pressurized (NCP)-TBM tunneling in rock with a comprehensive grouting program. In this paper, the authors will analyze the use of Shielded NCP TBMs at projects around the world as compared with slurry shield tunneling in rock under water pressure. Recommendations will be given in order to establish a clear picture of the optimal tunneling method.

Jun 13, 2021

By Arthur W. Ruff

Estimated reserves of high-grade iron ore at Serra dos Carajás total 16 billion metric tons and have an average grade of 66.7 percent iron, 2.2 percent combined silica and alumina, and 0.05 percent phosphorous on a dry basis. Hematite is predominant and no significant sulfur or other deleterious elements are present. Figure 1 illustrates the comparative magnitude of the Carajás reserves. Serra dos Carajás is located in northern Brazil, about 550 kilometers southwest of Belém, Pará. It is six degrees south of the equator between the Xingu and Tocantins Rivers. Both rivers flow northward toward the Amazon River. The greater part of the area is covered by thick jungle, and the most practical means of access is by air. Figures 2 and 3 show the location of Serra dos Carajás. Figure 4 shows the distribution of the major iron-ore deposits.

Jan 1, 1973

By Myron W. Mellor

Much has been published concerning the subject of coal preparation as related to electric power generation however it is always a most vital topic for both utilities and coal producers, It also constitutes a field of study that is never finished since new concepts and changing demands continually require altered perspectives. One graphic illustration that has been used to emphasize the rapidity with which times are changing is the fact that during World War I, a station that consumed 1000 tons per day was looked upon as a large central station, while today some single generators require 1500 tons during the same period, For further emphasis, at that time a 20,000 horsepower turbo-generator was a mighty large machine; today, a unit of this size is planned for driving the boiler water feed pump required for a single large main unit. During the past ten years alone, electric utilities have more than doubled their percentage of coal consumed as compared to the total market. They now account for approximately 40% of the United States consumption and one-third of all production including export, Conversely, approximately 70% of all U. S. steam electric generation is by coal and this percentage is expected to increase. It is further predicted that utility consumption will increase from the current 160,000,000 tons per year to between 400 and 500 million tons in 1975 which is approximately equal to todays total production

Jan 1, 1959

By D. M. Davidson

The economics of geologic exploration have changed materially in the past decade primarily due to the change in three basic factors, namely, increased wages and salaries, increased cost of materials, and a greater complexity in methods of exploration. Following the general economic pattern over the past ten years, exploration costs, have, in general, increased, although there is one heartening exception. A comparative picture is complicated because of advances in techniques which ensue from the introduction of new methods and devices largely for aerial exploratory work, Some of these methods were either in their infancy or unknown before World War II. Geological exploration may well be considered as a form of applied research. True, it has peculiarities from this standpoint some advantageous, others disadvantageous, Some of the advantages lie in the fact that exploration success does not involve the production of a new product which necessitates advertising expense and marketing problems. In normal times there is a well established market for the fruits of a successful mineral find. The outstanding disadvantage of exploration lies in the enigma of deciding when to quit if the sought fop prize is elusive. In the search for buried treasure, man?s curiosity is apt to color his judgment. Even the so-called detached scientist may fall 'all too readily into the wishful thinking of the old- time prospector who is lured on by the thought that the next pull from the drill hole, or the next round from the face will reveal a bonanza. It involves mature judgment and experience to ascertain the stage in exploration when further work is not justified.

Jan 1, 1958

By W. T. Reid

Analysis of the energy resources available in the United States confirms that coal will be needed to satisfy the future energy needs. The trends in the market place, particularly economic and political, suggest that the bulk of the coal will be consumed for generation of electricity. The utilization of coal to produce electricity will require technical solutions to the variable characteristics of coal and ash, development of methods to improve coal quality, and public acceptance of the cost of compliance with environmental standards.

Jan 1, 1983

By Qinbo Cao, Qianshan Peng, Heng Zou, Xingcai Yu

Rutile ore is an important resource for the production of titanium products, and flotation is an efficient method to enrich rutile from its deposits. Motivated by strong commercial demand for titanium metal and alloys, substantial efforts have been made to improve the flotation efficiency of rutile. Styryl phosphonic acid (SPA) and salicyl hydroxamic acid (SHA) are commonly used as collectors for rutile flotation, and lead (Pb) ions can be used as activators for rutile flotation with SPA or SHA. Xanthates have a price advantage over SPA and SHA for the flotation of sulfides as SPA and SHA prices are higher than xanthate prices. In this work, we found that when rutile is activated by lead ions, amyl xanthate is an efficient collector for rutile flotation at pH 8. A slightly basic slurry can be readily obtained. Moreover, the price of amyl xanthate is lower than that of SPA or SHA. In this regard, this flotation strategy has the potential to be used in industry. Furthermore, the adsorption features of amyl xanthate on the Pb-activated rutile surface was investigated by experimental methods, which provides insight into the role of lead ions in rutile flotation.

By Meredith Scaggs, Emily Sarver, Lucas Rojas Mendoza

"Early on Jan. 9, 2014, approximately 37,800 L (10,000 gal) of crude 4-methylcyclohexanemethanol (MCHM) leaked from a storage tank sitting on the bank of the Elk River near Charleston, WV (WVDEP, 2014; CSB, 2014). MCHM is a chemical commonly used in preparation of fine coal and is considered nonhazardous in terms of transportation, storage regulations and also toxicity (CDC, 2014a). Freedom Industries Inc., a producer and vendor of specialty chemical products, had acquired the storage facility from Etowah River Terminal, LLC just a few weeks prior in December 2013 (WVDEP, 2014; Freedom, 2005). The direct cause of the spill was ultimately determined to be two small holes in the base of the 76-year-old tank, which were created due to corrosion damage (Bauerlein and McWhirter, 2014).The spill site was located a little more than 1.6 km (1 mile) upstream from the intake of a municipal water treatment facility operated by West Virginia American Water (WVAW), which serves a population of 300,000 across nine counties in central West Virginia (CDC, 2014a). In a matter of hours, the leaked MCHM made its way through the treatment facility and into the water of nearby homes and businesses, where its strong smell was noticed almost immediately. On the evening of the spill, WVAW concluded that its conventional treatment processes, which include carbon filters to remove a variety of contaminants from water, were not capable of fully removing the MCHM and a "Do Not Use" order was issued for all customers (WVAW, 2014a).With little information readily available regarding the potential human health effects of MCHM, the U.S. Centers for Disease Control and Prevention (CDC) quickly issued an advisory ruling that set a maximum screening level of 1 ppm for safe drinking water (CDC, 2014a). Based on this recommendation, the "Do Not Use" order remained in effect for a total of eight days, until Jan. 17, when the WVAW distribution water was confirmed to have MCHM concentrations below the approved level (WVAW, 2014a). However, due to the pungent odor of the chemical, its presence was still recognizable in the WVAW facility and in consumers’ tap water after the order was lifted (Manuel, 2014). Recent studies have shown that the chemical can be detected in water at sub-ppb concentrations, a fact that undoubtedly added to growing public concern (Rosen et al., 2014; Gallagher et al., 2014). In response to numerous complaints and demands, WVAW continued flushing the treatment facility and pipes until Feb. 25 when MCHM levels were measured below 2 ppb (WVAW, 2014b), and eventually replaced the affected filter media (WVAW, 2014c)."

Jan 1, 2014

By Hassan El-Shall, Rosana M. Macedo Borges, Ponisseril Somasundaran, Regis Stana, José Renato B. Lima, Patrick Zhang

The phosphate fertilizer industry is a large activity in Brazil because the soil has a phosphorous deficiency. The phosphoric acid that is produced is extensively used in the production of fertilizer. It is produced by reacting phosphate carbonaceous rock with sulfuric acid, generating phosphogypsum as a by-product. In 1991, there were about 29 million tons of phosphogypsum stored in Brazil. This has increased to an estimated 280 million tons in 2001. While the phosphogypsum is used in the cement industry and also in agriculture, the quantity used is much less than the production rate, and the stockpiles are still increasing. The radioactivity of this waste may not allow its continued use as a construction material and some other uses. However, Brazilian phosphogypsum contains a smaller quantity of radioactive materials than is reported for phosphate rocks from other countries. One important reason is the geological origin of the Brazilian apatite. All the large deposits being currently mined are igneous, not sedimentary, as is the majority of the phosphate rock produced around the world. An extensive study is being conducted to characterize the phosphogypsum generated in two production facilities in Sao Paulo state to develop safe uses for this waste and determine the environmental impact caused by the present method of phosphogypsum disposal.

Jan 1, 2002

By R. H. Snow

Although industrial size reduction methods have an energy efficiency of only about 1 percent, methods of size reduction have not changed much for many years. One reason for slow progress has been the oversimple viewpoint that a single law should exist to relate size reduction to energy input. Modern simulation methods decompose the grinding process into a grinding rate function (selection function) and a breakage function. The breakage function is difficult to measure, and it usually requires tracers if it is determined from milling experiments. Prediction of breakage functions from basic principles is one objective of this paper. In this study we focus attention not on the gross energy input to the experiment, but on the spatial distribution of stress energy within the particle. We are led to this viewpoint by experimental observations of a few previous investigators (Bergstrom2, Rumpf3, Axelson4) and our own observations. Oka and Hiramatsu recently used their calculations of stress within particles for prediction of breakage, but again they tried to correlate the size of the fragments with the total stress energy, rather than the approach we propose. We assume that the stress energy is stored in the interior of the particle as the load is increased, until the particle breaks. We assume that each element of the particle breaks into fragments of a mean size that depends on the locally-stored stress energy. The size distribution of fragments is the computed from maps of the stress-

Jan 1, 1972

By Bruce R. Sutherland, Jim B. Ramsden, Gerry L. Bolton

Conductive metal powders are important building blocks for today's micro-electronic circuitry. Formulated into inks, they provide the interconnects needed to complete a complex integrated circuit and the means to enter the world of miniaturization. Traditionally, the inks have been based upon expensive metals such as silver, palladium, platinum and gold because of their excellent electrical conductivity and resistance to corrosion and oxidation. The use of a copper based ink, as an alternative to precious metal inks, recently has received considerable attention. Instability in the prices and limited supply of certain precious metal systems have driven up production costs, making the development of a lower cost copper system more attractive to manufacturers. However, lower production costs are on1 y real ized if performance and reliability can be maintained. While the development has been driven by cost, copper does offer some significant performance advantages over noble metal systems: conductivity as good as silver and 4W better than gold; leach resistance better than silver and equal to gold; stability at high frequencies better than gold or silver; strong film bonding characteristics; and compatibility with most solders. These benefits, however, do not come without cost. The inherently reactive nature of pure copper, while providing unique performance properties, makes it difficult to process. Unl i ke precious metals which can be fired in air, copper would oxidize and so requires special furnaces and atmospheres. Despite these difficulties, the transition from precious metal thick film systems to copper is gaining momentum. Manufacturers of high density, high performance circuitry are exploring the performance advantages of copper over gold and silver and the manufacturers of consumer products are considering the potential cost savings of copper over silver-palladium. Sherritt has developed a fine copper powder for this industry. Through association with the ink manufacturers, it has been found that performance properties of the ink vary with the physical and chemical characteristics of the powder. Production Process The production of very fine copper powders at Sherritt is based upon the disproportionation of cuprous ions as outlined in Equation [1] (1).

Jan 1, 1990

By David Hartley

United States Steel Corporation Minntac Mine is located at Mt. Iron, Minnesota, on the Mesabi Iron Range. The taconite pit is two miles long by a mile wide, with a maximum depth of 170 feet. This paper will deal with the radio remote control of locomotives engaged in the railroad haulage of crude ore and waste rock at this property.

Jan 1, 1970

By T. H. Koenning

Spontaneous combustion in western U.S. coal mines has been recognized as a serious problem which requires unique solutions. Methods have been developed for longwall mining which rely on the existence of an oxygen-deficient atmosphere in the gob for control of the spontaneous combustion hazard rather than the use of bleeder systems. Monitoring of the gob atmosphere is required to protect against the possibility of an explosion and to detect spontaneous heatings. Data from an example mine employing such a system is included to illustrate normal gob gas trends and is compared to abnormal trends which resulted from and were indicative of a fire. Under normal circumstances the oxygen (O2) and carbon monoxide (CO) concentrations decline rapidly as the longwall face retreats. Samples taken from a leaking seal in the example mine prior to a spontaneous heating showed virtually no oxygen depletion, contained erratic CO concentrations, and indicated the existence of hydrogen, a fire indicator. The appearance of an abnormal trend in the gob atmosphere can be used as an early warning of spontaneous heatings.

Jan 1, 1992

By Howard E. Kremers

Although more than 100 thorium-rare earth minerals are known, only a few have any commercial significance. Monazite, thorite, bastnasite, and some exotic thorium rare earth ores are reviewed Commercial interest is presently centered on monazite from the Union of South Africa, and thorite from this country. Thorium became commercially important with the development of the incandescent gas mantle about 75 years ago, Gas mantles consist of thorium oxide with small amounts of cerium oxide. The thorium nitrate used to make gas mantles was first obtained from rare thorium minerals, As a matter of fact, this use of thorium is still important and is one of the largest commercial uses for thorium materials. The discovery of monazite sand placer deposits along the coasts of Travancore, India, and in some Brazilian beach s .s, and the development of the old North and South Carolina monazite stream placers gave the mantle industry of 30 to 40 years ago a comfortable inventory of thorium ore. Even today, the thorium industry depends largely upon monazite ores for its source of thorium. This paper will briefly describe some of the major thorium ores and their principal deposits insofar as they relate to the thorium industry in this country. Because of similar chemical and physical properties, thorium always occurs with the rare earth elements and with varying amounts of yttrium. Thorium may predominate over rare earths, as in thorite-type minerals, or may represent only a fraction of the rare earth content. Typical ratios of thorium to rare earths in various minerals are given in Table 1, The average thorium content of the earth's crust is about 12 grams per ton, and in this respect thorium approximates lead, molybdenum, and some of the rare earths in abundance. The ore minerals of greatest importance to the-thorium-rare earth industry are monazite, thorite-type minerals, bastnasite-type- ores, and the family of minerals which is characterized by a preponderance of the heavy rare earths and yttrium. The latter classification includes xenotime, gadolinite, samarskite, euxenite, etc, The first two, monazite and thorite, are of greatest significance.

Jan 1, 1958