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By Charles Barrett

RECRYSTALLIZATION textures-the orientations of grains after recrys-tallization-have been studied extensively not only because of their metallurgical importance but also because of the information they yield regarding the atomic movements during recrystallization. Recrystallized grains must possess the same orientations as the submicroscopic nuclei from which they have grown, and thus they offer a direct road by which experimenters can penetrate the submicroscopic realm. Many perplexing results have come of these studies, but one of the most striking has been the apparent difference in behavior between single crystals and polycrystalline grains. For example, Burgers and Louwerse have shown' that when single crystals of aluminum are deformed by compression and are recrystallized (at 600° C.) the new grains appear with orientations that are different from the orientations of the deformed crystal in which they grew; but polycrystalline specimens, on the other hand, appear to have a [110] fiber texture both before and after recrystal-lization and thus to retain their texture during recrystallization. This apparent difference between the habits of single crystals and small grains is the subject of the first part of the present research and has been explained by findings reported herein. A similar situation appears to exist for aluminum when elongated or drawn into wires, for single crystals alter their orientation2,3 and polycrystalline wires retain their texture 4,1 6 upon recrystallization after elongation (at least with high-purity alumi-num), and it is possible that the explanation found in this paper for compression can be extended to cover elongation and other types of deformation as well. The second part of this paper deals with the theory of recrystallization textures. In the most successful theory for aluminum recrystallized after compression,1 much weight is given to the orientation of highly stressed nuclei in the deformed material. Taylor's "local distortions" are assumed to exist along the slip planes where displacement has occurred, consisting of fragments rotated in a specific way with reference to the slip plane and slip direction; namely, about an axis lying in the slip plane perpendicular to the slip direction. 1,7,8,9

Jan 1, 1940

By Jean-Michel Rendu

In most mining operations, some degree of selectivity is applied. Whether one deals with surface or underground operation, ore zones, and waste zones are defined not only on the basis of the value of the ore contained, but also taking mining constraints into account. A number of computer techniques are presented which can be used to determine the optimum location of the footwall and hanging wall of ore zones intersected by drill holes. Minimum mining width and minimum internal waste width constraints are taken into account, as well as other economic constraints. The system is presented as an integral part of a larger manumatic ore reserve and mine planning system.

Jan 1, 1982

Jan 1, 1976

By C. Villachica

El presente texto refiere las recuperaciones de los metales (oro y plata) contenidos en productos intermedios de las minas, concentradoras, fundición y refinerías. Asimismo, se considera la lixiviación de plata en botaderos, flotación de escorias de convertidoras de cobre, flotación de escorias convertidoras de anódicos, separación de valores de refractarios usados y la recuperación de plata de relaves y productos intermedio de concentradoras.

Oct 14, 1980

By Chunhui Zhang, Enton Bedini, Jiang Chen, Fengchao Yang, Hang Dong, Xiaoyan Chen

The alteration formed by the reaction of ore-bearing fluid and wall rock is often used as an important prospecting indicator, resulting in the dilution or enrichment of metals or related trace elements. A variety of rock-forming and metallogenic elements have been analyzed in regional stream sediments so that the relationship between the ore-bearing altered rock and the change in the geochemical elemental content can be obtained. Therefore, by using appropriate models, such as matched filtering, the abundance of the distribution of wall rock alteration, similar to the discovered deposits, can be modeled by using the distribution of geochemical elements in the region, and the areas with high distribution abundances are usually favorable prospecting targets. The alteration types related to gold mineralization in the Baiyun gold deposit are potassium feldspar alteration, silicification, pyritization, sericitization, and chloritization. In this paper, the geochemical data of the Qingchengzi ore field (1:200,000 and 1:50,000) have been used to form geochemical images through rasterization. In the three sections of the Baiyun gold deposit, binary-coded curves have been formed, revealing the differences in geochemical elements in stream sediments between altered rocks and the rocks surrounding the Baiyun gold mine. Among them, Au, W, and Mo are enriched elements, while Sn, Zn, and Hg are depleted elements. Several gold deposits are found in the predicted altered rock area by using the matched filtering method during fieldwork, which shows the effectiveness of the method.

Dec 30, 2023

By J. M. Singer

The objective of this investigation was to determine minimum air velocities and entrainment rates for coal and rock dust dispersion in wind tunnel experiments under conditions that simulate dispersion from surfaces in coal mines where airflows are induced by weak gas explosions. Dust deposits were bed-or ridge-shaped; particle sizes were 6 to 80 microns (cohesive deposits) or 100 to 150 microns (free-flowing deposits); and wind tunnels were 7.62 cm wide by 5.08 cm high by 300 cm long, and 2.4 m wide by 1.5 m high by 215 m long. The investigation showed that minimum air velocities (directed at mid-height) of separate, layered, or mixed piles of coal dust and rock dust were within the range 5 to 30 m/sec, independent of size of wind tunnel. This finding considerably facilitates scaling of data to mine-size passageways. Free-flowing deposits dispersed relatively slowly by single-particle detachment; cohesive dusts dispersed faster by the breaking and lifting of large clumps along weak failure flames; particle dispersion occurred in flight. Layered or mixed deposits of coal and rock dust did not disperse selectively. Semiempirical expressions were derived relating minimum air velocities and dispersion rates to dust-pile geometry, cohesion, porosity, and bulk density.

Jan 1, 1972

By A. A. Giardini

This report represents the results of a literature study on boron nitride and related substances. The purpose of the study was to find Information that might be of value for production of a new, hard modification of boron nitride preferably in single crystal form. The report consists of a review of the major developments in boron nitride research, a discussion of the results, tabulations of physical and chemical properties;, conclusions drawn from the study, and a bibliography.

Jan 1, 1953

By G. W. Leney

Iron ores occur in such a wide variety of forms that nearly every kind of prospecting, geological knowledge, and geophysical technique has some application in the search for them. The type of orebody that is considered desirable depends on political and economic considerations, on transportation and markets, on the characteristics of the orebody, on the metallurgy of the ore, and on its comparison with other available ores. In North America, materials that can be efficiently processed into high grade concentrates and pellets are now the object of most exploration work. These are usually shallow, relatively unoxidized, metamorphosed iron formations that are particularly suitable for geophysical methods of exploration. Magnetic surveys are used for the direct discovery of new orebodies, for mapping stratigraphy and structure, and at times to locate oxidized zones in magnetic iron formation. Gravity mapping provides supplementary information, indicates gross tonnages, is useful in regional studies, and can discover non-magnetic orebodies. Electrical methods have not been fully exploited but self-potential, resistivity, applied potential, electromagnetic and perhaps induced polarization surveys all have restricted but highly useful applications. The use of all geophysical techniques promises to increase as the number of exposed easily discoverable orebodies decreases. A high consumption of steel, and consequently of iron ore is the chief characteristic of an industrial society and this consumption has been increasing at an average rate of about 35% every ten years for the past century. To supply this demand, iron ores and iron bearing materials in a wide variety of forms have been exploited on every inhabited continent and in nearly every country. Nearly every kind of prospecting, geological knowledge and geophysical technique has some application in the search for them. The type of orebody that is con-

Jan 1, 1964

By P. K. Kaiser, S. M. Maloney, S. P. Singh

"Corrosion of underground support measures constitutes a concern to industry in both safety and economic terms. It also represents a potential market for corrosion resistant materials such as stainless steel.In order to assess the market potential for a stainless steel friction rock bolt, a review of current corrosion processes and remedial or preventative measures in the underground environment was undertaken. This was supplemented by distribution to industry of a detailed questionnaire, concerning the magnitude and extent of support corrosion and the costs of current support measures, and by visits to selected sites. Following data synthesis, support costs were established and the economic benefit of stainless steel rock bolts evaluated.Stainless steel rock bolts can be an effective cost reducing measure in unscreened areas requiring frequent reconditioning. Their benefit is rapidly diminished, however, if only partial reconditioning is required, the reconditioning interval is long or if screening is required.While most industry personnel are receptive to the application of stainless steel support measures, the localization of corrosion problems and the potential high cost of this type of support are barriers to its widespread implementation. They have potential for use in extreme environments. However, this relatively small market may not be economically viable.IntroductionFriction rock bolts are the simplest of all interior rock fixtures. The friction resistance to sliding of the rock on the bolt is generated by a radial pressure against the borehole wall over the length of the bolt. Two types of friction rock bolts are currently marketed, the Split Set and the Swellex.Unlike conventional point anchor bolts, friction rock stabilizers may move relative to the rock strata and maintain their capacity even if rock shifts, a condition that sometimes loosens or breaks conventional bolts. Ease of installation, effectiveness in jointed as well as weaker rock, and the possibility of having relatively long bolts are a few of the many advantages which generate considerable interest in the application of friction rock bolts (Wijk and Skogberg, 1982). However, due to their thin-walled construction and large surface area, frictional rock stabilizers are more susceptible than conventional bolts to damage by corrosion. For this reason, they are normally not recommended for long-term use (Jolly and Neumeier, 1987).In light of the above discussion; the Nickel Development Institute commissioned a study by the Geomechanics Research Centre with the objective of generating a credible database for the assessment of the feasibility of a stainless steel friction bolt system in corrosive ground and mine environments."

Jan 1, 1990

By H. M. Cooper

The determination of moisture in coal is an empirical test, because the time, temperature, and equipment are specified. The essential features of the equipment and details of the procedure are given in A.S.T.M. Designation: D271-44.:2. According to the specifications, the following features should be incorporated in the equipment used: 1. Oven must have uniform temperature in all parts. 2. Oven must be constructed with minimum of air space. 3. Oven must have means of changing the air two to four times per minute. 4. Air must be dried over sulfuric acid (sp. f-7. 1.84). The analytical procedures governing most of the nation's coal purchases are those given in A.S.T.M. Standards referred to above. These standards are general arid of such scope as to cover all ranks and types of coal. In cases where only the moisture is required, a faster method than the standard procedure is desired.

Jan 1, 1948

By Henry G. Granger, Edward B. Treville

The Republic of Colombia is the northernmost country of South America. Its northern coast line exteilds from the frontier of Costa Rica to that of Venezuela, on the Caribbean Sea. On the west it fronts on the Pacific Ocean, along the Panama Isthmus, and down to Ecuador. It is bounded on the south by Ecuador, Peru and Brazil, which latter country with Venezuela form its boundaries on the east. Its area exceeds 500,000 square miles. It is deemed unnecessary to give here a map of the country. Fig. 1, a map of the department of Antioquia, studied in connection with a good modern general map of Colombia, will explain itself. Fig. 1 contains also some of the region of the Cauca valley, described in this paper. Access.—The interior of Colombia is reached through the ports of Sabanilla and Cartagena on the Caribbean Sea, each of which places is connected with the Magdalena river by a short narrow-gauge railroad, running respectively to Barranquilla and Calamar. From these points lines of river-steamers serve the ports of the upper Magdalena, which they reach in journeys of a week to ten days. After leaving the steamer, a short railroad journey, followed by a long and tedious mule-ride, reaches the cities of Bogota and Medellin. Quibdo, at the head of the navigation of the Atrato, and its most important town, is connected by steamer-service with Cartagena, by canoe-routes with the various districts of the Choco, and by mule-road, at present well-nigh impassable, with the heart of Antioquia. On the western coast the port of Tumaco is a starting-point for canoe- and mule-travel to the southern part of the department of Cauca, while Buenaventura is the port of the central section of the valley of the Cauca,

Jan 1, 1899

By G. C. Yao

Iron and silicon impurities can form needle and branch shape intermetallie compounds in molten aluminum when there is no manganese. It is difficult to separate them from molten aluminum by electromagnetic separation. The Fe-Si-AI and Fe-AI intcrmetallic compounds were transformed into Mn-Fe-Si-AI and Mn-Fe-AI compounds by the addition of manganesc into molten aluminum, In molten aluminum the morphology of these intermetallic compound particles is lumpish and spherical. Migration resistance of these impurity particles is small, which is beneficial to separation. FeSiMnAl4 and FeMnAl6 arc paramagnetic. These impurity particles can be moved by magnetic force and can be separated from the molten aluminum.

Jan 1, 2003

By Matheus Fortes Stiborski

O emprego de materiais sinterizados para conformação massiva permite a utilização de forças menores permitindo que resultados similares sejam alcançados com maquinas de potência menor, outra vantagem é que o blank utilizado para esse processo não contém tensões residuais advindas do processo anterior. Para o processo foi necessário o levantamento das curvas de compressibilidade do material a ser estudado (pó de ferro puro), análise das propriedades do material sinterizado e posteriormente extrusão do material e caracterização do mesmo.

Aug 17, 2017

By E. Seidl

THE basic material for testing aluminum, copper and zinc is a cast metal, principally in the form of wire bars (Figs. 1 to 3) and plates for the produc- tion of sheets or strips, (Figs. 4 to 7). Experience has proved that the chemical and crystallographic proper-ties of such cast metal exercise a certain influence when it is being worked, which is usually done while the metal is hot. In a chemical sense the slight impurities, which even the purest industrial metal contains, have a disturbing effect. They settle either along the outside limits of granulation, as in the case of aluminum and copper, or else in the interior of the crystal, as in the case of zinc; but frequently are also found accumulating at certain points (formation of the blowholes and skin) (Fig. 7). The crystallographic character of the metals is either that of uniformly fine granulation, or else there occurs a certain distinct casting texture marked by sharply defined cooling conditions and consisting of crys-tals of a pronounced stalk-like or blade form. Since we generally distinguish between a crystal texture and a crystal structure, the term crystal texture is used here for the arrangement of the crystals relative to each other and their microscopic composition; crystallic structure is used to mean the radioscopically ascertain-able structure of the crystal. The influence of the impurities and of the crystalline character on the working of the metals has been fre-quently pointed out in practice as well as in science.

Jan 11, 1927

By S. H. Ash

The Pennsylvania anthracite-mining region is the only one in the world of major magnitude. As the deposits of anthracite in the United States are limited virt113.lly to Pennsylvania, the difficulties of this industry have been commonly considered a State rather than a national problem. However, there is also national interest in the conservation and wise utilization of all fuel resources and in the control of interstate waterways. The anthracite industry is confronted with the very se:;-ious :problem of accumu.lation of water in many of the mines. This problem must be solved soon if progressively higr-er mi~ing costs are to be avoided. The water proble~ cannot be solved by the operating compa,nies without State or Federal aid, or both, owing to the magnitude of the work requir~d, diversity of interests of the coal ana surfa.ce ovmerships, hazard to the whole mining community, and interests affec~ed outside the mining region. The cost of abati~ the ever-increasing_surface seepage to mine workings and of handling this seepage once it }3s occurred is beyond the economic resources of most ope~ating ma.'18.gements. The data in this paper giving the high lights of the water problem and indicating what appears to be a step in the right direction are based upon observations made during the past year that the industry desires and believes it is to the npublic interesttr to keep mine workings free of flood end surface waters.

May 1, 1941

By J. K. Ahlness

The Bureau of Mines investigated technologies for determining the integrity of in situ leach mining wells. A self-contained trailer-mounted well integrity testing system (WITS) was designed and built to enable rapid testing of well casings for leaks as required by environmental regulations. The WITS utilizes two inflatable packers to seal off the entire casing length or any portion thereof. Water pressure is built between the packers to the desired test pressure, and the presence or absence of casing leaks is determined by monitoring the pressure drop between the packers. A winch and steel cable are used to run the packers in and out of the well. The WITS underwent an industry field test at the Irigaray in situ uranium leaching mine near Buffalo, WY. A total of 37 wells with an average depth of 225 ft (69 m) were tested at an average rate of four wells per 8-h shift with a two-person operating crew. This represents a 75-pct time savings and an 83-pct labor savings compared to the rigid-pipe method previously used at the mine, with which a three-person crew tested an average of one well per shift.

Jan 1, 1986

By T. Wajima

"A novel carbonaceous immobilizing agent for heavy metal contaminated soil was prepared from rice straw using sulfur immersion and pyrolysis, and the lead immobilization in artificial contaminated soils using sulfur-impregnated carbonaceous material was estimated. The rice straws were cut to 1 cm pieces, and then immersed in 0.1 - 1 M K2S solution for 0 - 24 h to prepare sulfur-immersed materials. The immersed-materials were heated at 400 oC for 1 h in nitrogen gas to produce the sulfur-impregnated carbonaceous material by pyrolysis. The abilities of the product to immobilize lead from aqueous solution were examined to obtain the product with high lead immobilization ability. With increasing K2S concentration, the immobilization ability of the product for lead gradually increases and then above 0.5 M K2S those are almost constant, while 15 min is sufficient for the immersed time to obtain the product with high lead immobilization ability. The product prepared from material immersed in more than 0.5 M K2S solution for less than 15 min has a maximum immobilization ability for lead ion. The lead immobilization using the sulfur-impregnated product is sustainable due to the formation of leadhillite [Pb4SO4(CO3)2(OH)2] and anglesite [PbSO4]. The product can immobilize lead ion in various artificial lead contaminated soils. By mixing artificial lead contaminated soil with the sulfur-impregnated product, the eluted solution became neutral, and the eluted concentrations of lead ion dropped below the Japanese elution standard for soil.INTRODUCTION Soil contamination with heavy metals is a worldwide problem. Accumulation of heavy metals in soils affect soil ecology, agricultural productivity, quality of agricultural products, water resources, and serious health problems for human and animal (Raicevic, et al., 2005). In the United States, for example, approximately 63 % of the sites on the National Priority List (NPL) for the treatment of contaminated soils are contaminated by metals, and lead is the most common metal, found at 15 % of the sites. In Japan, according to a report by the Ministry of Environment, 43 % of the contaminated sites that exceed the environmental quality standards are contaminated by lead compounds. Soil contamination by lead compounds is also prevalent in other developed and developing countries where lead compounds are used extensively in industrial activities without careful contamination management. Lead is a ubiquitous heavy metal pollutant in soils due to their use widely. The primary sources of Pb contamination include industrial activities such as mining, smelting of metals, and the use of Pb-containing products such as paints, lead-acid batteries, bullets, gasoline and pesticides (Cao, et al., 2009). It can damage human nervous (especially children) and reproductive systems (ATSDR, 2007). The high concentration of Pb in the soil poses risks to human and animal health by the leaching of metals from the soil into water and the consumption of edible plants growth in the contaminated soil. Therefore, proper remediation is necessary to reduce metal availability in soil for protecting human health."

Jan 1, 2018

By H. M. King

A combination of chemical, statistical, geographic, and microscopic analyses reveal that sulfur in West Virginia coals is extremely variable in both form and abundance. Coals in southern West Virginia typically contain less than 1% total sulfur with organic sulfur being the dominant species. Northern West Virginia coals average about 2% total sulfur, mainly contributed by sulfur minerals. In addition to these regional trends, significant variations in sulfur form and abundance exist both vertically and laterally within individual seams. On both regional and local scales, the pyritic sulfur component can vary significantly in mineralogy, particle shape, maceral association, and particle size.

Jan 1, 1986

By Kepplinger W

The KR Process is a joint development by VOEST-ALPINE, Austria and its subsidiary company KORF ENGINEERING, Germany. This new technology allows production of hot metal on the basis of non-coking coal. The KR Process is based on the idea of separating the process steps realized in the blast furnace (generation of reduction gas, reduction of iron oxide and melting of the reduced iron) and including coking of coal. These reactions are carried out in two reactors: - the melter gasifier, where non- coking coal is coked and gasified into a high quality reduction gas and hot prereduced iron is melted. - the reduction furnace, where iron oxide is reduced by the reduction gas generated in the melter gasifier and discharged in a hot state. In order to prove the process a pilot plant has been set up in Kehl/ Rhine in 1981 with a nominal capacity of 60.000 tpy.

Jan 1, 1986

By Leonard Grimshaw

THE idea of bonding two dissimilar ferrous metals, and making use of both, is an old one. Tips have been brazed onto tool shanks for many years. The bonding of larger pieces to form whole bars and sheets has also been accomplished, but has received little attention in the technical literature, although a number of patents have been issued covering various methods for its accomplishment. There are three main motives behind the manufacture of composite steels. One is that the physical properties of one steel may supplement those of another; a useful, but at the same time, hard, brittle steel may be backed by a soft ductile one, or a stainless steel may be backed by a steel possessing greater strength. Another motive is direct lowering of cost; an expensive steel may be backed by a less expensive one, bringing down the cost of the piece as a whole. The third motive is an indirect lowering of cost, as when a useful steel is backed by a steel that is easier to machine, so that machining cost on a finished product is lowered considerably. Often more than one of these motives lead to a decision to use a com-posite steel.

Jan 1, 1936