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By G-L. Wu, S-W. Wu

"The hot deformation behaviour of Nb-Ti microalloyed high-strength steel was investigated. Hot compression tests were conducted in the temperature range 900 to 1100°C under strain rates of 0.1, 1, and 5 s-1. Dynamic recrystallization (DRX) occurs as the main flow softening mechanism at high temperature and low strain rate. The hot deformation activation energy was calculated to be about 404 699 J/mol. The constitutive equation was developed to describe the relationship between peak stress, strain rate, and deformation temperature. The characteristics of DRX at different deformation conditions were extracted from the stressstrain curves using the work hardening parameter. The Cingara-McQueen equation was developed to predict the flow curves up to the peak strain. The processing maps were obtained on the basis of a dynamic materials model. The results predict an instability region in the temperature range 1010 to 1100°C when the strain rate exceeds 0.78 s-1. IntroductionThe 700 MPa grade HSLA steel is widely used in engineering machinery, automotive beams, carriages, and axle tubes, etc. (Pan et al., 2017 ). Generally, such grades contain a moderately high amount of Mn (approx. 1.4% and above), and microalloying elements like Nb, Ti, V, and Mo to impart the desired strength and toughness through solid-solution strengthening, precipitation hardening, and grain refinement dislocation strengthening (Chen and Yu, 2012; Opiela, 2014). However, the production costs can be greatly reduced by replacing part of the Nb, V, or Mo with inexpensive Ti and adopting the compact strip production CSP process (Opiela, 2014; Chen et al., 2015). Furthermore, the microalloying technology coupled with new-generation thermomechanical control processing (NG-TMCP) has proved efficient for achieving the proper balance between strength, toughness, ductility, and formability by means of a suitable combination of chemical composition and thermomechanical treatment parameters (Shukla et al., 2012; Wu, Zhou, and Liu, 2017).In hot forming processes, the complex microstructural evolutions are often induced by multiplicative hot deformation mechanisms, such as work hardening (WH), dynamic recovery (DRV), and dynamic recrystallization (DRX) (Zhang et al., 2014; Liang et al., 2015). Dynamic softening behaviour during hot processing has generated considerable interest because component properties are influenced significantly by its corresponding microstructural evolution (Wu et al., 2010). During deformation in the DRX process, deformed grains are replaced with substructures and newly formed fine and uniformly distributed grains. This occurs only when a critical strain for the onset of DRX is reached, and at the same time, the minimum rate of energy dissipating is reached (Ferdowsi et al., 2014). DRV occurs at a high strain rate and low temperature, reducing the stored energy greatly and making DRX difficult (Liang et al., 2015). The microstructural changes during DRX are sensitive to the processing parameters, such as strain rate, deformation temperature, and strain (Zhang et al., 2014; Ferdowsi et al., 2014). Therefore, in order to optimize the hot processing parameters, it is important to understand the behaviour of hot deformation visà- vis control of microstructural evolution."

May 1, 2019

By Oliver Bowles

"General.The term mica is probably derived from the Latin ""micare"", meaning to shine or glitter, for the brilliant reflection from mica flakes in rocks has directed more than ordinary attention to this group of minerals. Mica includes a group of several minerals all characterized by a perfect basal cleavage, by virtue of which they may be split into exceedingly thin plates. The minerals are of very common occurrence in all countries, constituting about 4 per cent of the igneous rocks of the world The term ""isinglass"" is sometimes applied to glazing mica, but this is incorrect, for true isinglass is a soluble combustible material made from the air bladders of certain fish. As a constituent of granites and schists, mica is present as flakes too small for commercial use. Mica occurs also as small scales in many sandstones. When granites decompose, the quartz and the white mica are the most resistant to weathering, and so remain when the other constituents have been decomposed and carried away. A secondary white mica known as sericite is formed by the metamorphosis of clay-bearing rocks, and thus, in extremely fine-grained form it constitutes an important constituent of slates and related rocks. Some schists contain a high percentage of mica, but the presence of large amounts of quartz and other minerals has up to the present time rendered them useless as commercial sources of mica for grinding. It is possible, however, that certain mica or seri-cite schists which are composed almost wholly of mica with very little quartz may be utilized for ground mica if found in large enough entity. Considerable micais sometimes found mixed with the residual kaolin that results from decomposition of pegmatites, and in one locality at least it has been recovered as a by-product in a clay purification plant."

May 1, 1922

By Daniel J. Schulze

Abstract-Eclogite is an important source of diamond in the upper mantle, but is more localized than peridotite. Using eclogitic minerals in kimberlite and diamond exploration is also more problematic than using the well-known peridotite-derived indicator minerals Cr-pyrope and magnesiochromite. The problems include color similarities between orange garnets from eclogites, Cr-poor megacrysts, and crustal garnets, chemical similarities with Cr-poor megacryst suite garnets (specifically elevated Na2O contents), and low abundance of eclogite garnet xenocrysts in most known kimberlites. Chemical screens must be used carefully to distinguish between varieties of orange garnets in exploration samples. For example, most orange garnets of crustal origin have >22 wt% FeO, with mantle eclogite garnets having lower values. Na2O-bearing garnets from the Cr-poor megacryst suite can be distinguished from Na2O-bearing garnets from diamondiferous eclogites by the elevated TiO2 contents of the former. The low abundance of eclogite garnet xenocrysts in kimberlites worldwide, however, may dictate that use of eclogite garnets in diamond exploration in most cases be restricted to advanced stages of kimberlite exploration and evaluation of kimberlite diamond potential. Crpyropes, Mg-ilmenites and Cr-rich chromites are more useful than eclogitic garnets in most stages of diamond exploration. If orange garnet xenocrysts are sought in a kimberlite exploration program, those from the Cr-poor megacryst suite will be more useful than eclogite derived garnets, due to the typical great abundance of the former, although they carry no information of the diamond potential of the host kimberlite.

Jan 1, 1997

By Daniel J. Schulze

Eclogite is an important source of diamond in the upper mantle, but is more localized than peridotite. Using eclogitic minerals in kimberlite and diamond exploration is also more problematic than using the well-known peridotite-derived indicator minerals Cr-pyrope and magnesio-chromite. The problems include color similarities between orange garnets from eclogites, Cr-poor megacrysts, and crustal garnets, chemical similarities with Cr-poor megacryst suite garnets (speci?cally elevated Na2O contents), and low abundance of eclogite garnet xenocrysts in most known kimberlites. Chemical screens must be used carefully to distinguish between varieties of orange garnetsin exploration samples. For example, most orange garnets of crustal origin have >22 wt% FeO, with mantle eclogite garnets having lower values. Na2O-bearing garnets from the Cr-poor megacryst suite can be distinguished from Na2O-bearing garnets from diamondiferous eclogites by the elevated TiO2contents of the former. The low abundance of eclogite garnet xenocrysts in kimberlites worldwide, however, may dictate that use of eclogite garnets in diamond exploration in most cases be restricted to advanced stages of kimberlite exploration and evaluation of kimberlite diamond potential. Cr-pyropes, Mg-ilmenites and Cr-rich chromites are more useful than eclogitic garnets in most stages of diamond exploration. If orange garnet xenocrysts are sought in a kimberlite exploration program, those from the Cr-poor megacryst suite will be more useful than eclogite derived garnets, due to the typical great abundance of the former, although they carry no information of the diamond potential of the host kimberlite.

Jan 1, 1997

?Bank Lending to the Mining Sector affected by 2 broad factors since Mid 2008: 1. Economic Downturn (?the Real Economy?) for mining companies directly reflected in lower metal prices (current and forecasted). In the case of gold companies, minimal effect. 2. Financial Crisis (?the Credit Crunch?) as it has affected the lending activities of those banks active in the mining sector.

May 1, 2009

By Robert T. McKnight

Introduction The minerals exploration business, like many businesses, is faced with the problem of valuing future, risky cashflows. These cashflows are derived from those mineral deposits which have been successfully commercialized. Many deposits, however, do not have the quantities or grade of ore to be considered economic at the projected metal prices using the traditional tools of the Capital Asset Pricing Model and discounted cashflow analyses. If one calculates the future revenues, costs and cashflows of one these marginal properties, and discounted it at the appropriate risk-adjusted discount rate, it may have a negative present value. Yet such a property may still have real, positive value in the marketplace. Why would a firm pay money for a property with an (apparent) minus present value? Mining properties such as these are bought and sold in arms- length transactions on a regular basis. Why is this so? Part of the reason relates to the nature of ore reserve information. To generate cashflows, the analyst must t assume that the reserve information is known with certainty when, in fact, reserves are not known with certainty. Mineral reserves are a function of commodity price, extraction costs and the level of (usually drilling) information about the reserves. Stated, or currently known, mineral inventories may vastly understate the true state of nature. Some firms may therefore be buying a property based on a completely

Jan 1, 1988

By S. V. Bogdanov, S. I. Grishaev

"The article presents the materials about the appropriateness of the use of rental indices to assess the effectiveness of the use of deposits of rare earth elements (REE). The authors suggest from the standpoint of rent payments to rate for the owner the possibility of using the anticipated rental income as the indicator for the analysis of preferences and economic significance of enrichment of extracted raw materials in the emerging field of rare earth metals (REE). Usually from ore mined at the fields, for flotation technology to produce concentrates with collective REE, then they are subjected to chemical-metallurgical processing of the received products are divided into pure oxides, chemical compounds or isolated from them pure metals and alloys. This commercial product is shipped to the buyer. REE were a non-renewable natural resources, so the calculations for determining differential and specific rent showed that during the development of the technologies of mineral processing of a specific field it is necessary to consider what the expected rental income depends on the magnitude of differential rent is related to the volume of production of REE for the whole planned period of exploitation of natural resources. This income is determined by the amount of stock field. For long-term exploitation of the deposit is observed in almost direct proportional dependence between the annual differential rent and the rental income. The decrease in rents in the long run is determined by the change in the composition of ores included in the extracted raw materials and the balance between light and heavy REE. The largest 70% reduction of the rent projected for ""cerium"" fields, while for ""yttrium"" these losses are considerably smaller. Tomtor, Chuktukon and Katuginskoye Russian deposits are characterized by a level of rent that is comparable to the mastered foreign sources of REE. Thus, the enrichment of minerals with REM in the domestic deposits is quite competitive at the world level. INTRODUCTION Deposits of rare earth metals (REE) are non-renewable resources that should be developed and used so that it would be possible to provide a reduction due to payment of appropriate resources for future generations. This compensation, due to the reduction of natural resources, can be carried out both in natural and in economic terms (1). When analyzing economic compensation options, particular attention should be paid to rental income in assessing the attractiveness of using different REE deposits. It is known that absolute and differential rents are summands when calculating the value of natural rents. The value of the absolute natural rent is proportional to the unit price of the product obtained from mineral raw materials and sold on the commodity market. Limitations, as well as the use in production processes and business, contribute to the gradual reduction of natural resources, which increases their consumer value and affects the price of commodity products from primary raw materials."

Jan 1, 2018

By Eckhard Nembach

The phase diagram of the system Pb-In has been investigated between -27° and + 40°C, using nzainly X-ray dijfraction. In accordance with t her mo dynamic measurements by Heumann and Predel, a segregation occurs at low temperatures, though not in the form of a nziscibility gap. THE phase diagram of the system Pb-In has been the subject of extensive investigations,1&apos;1 but recently Heumann and prede13 concluded from their thermodynamic data that a new feature should occur below room temperature. These authors observed that the maximum values for the enthalpy and entropy of mixing, which occurred at a composition of 50 at. pct Pb, were +400 and —1.7 cal per g-atom deg, respectively. From this the authors estimated that a miscibility gap should occur below 30°C, centered at 50 at. pct Pb. Resistivity measurements seemed to support this view. These authors proposed the phase diagram outlined in Fig. 1. Three phases exist at 30°C: the tetragonal indium phase with c/a > 1, the tetragonal intermediate phase a, with c/a < 1, and the fcc lead phase. During an investigation of the superconducting properties of Pb-In alloys. it has been observed4 that aging a specimen with 50 at. pct Pb for 14 days at -18°C decreased the superconducting transition temperature about 0.13"K and tripled the transition width. In this paper, the results of an investigation of the Pb-In phase diagram in the temperature range from — 2T to +40°C are reported. Superconductivity and X-ray methods have been used. 1) SPECIMEN PREPARATION The materials were provided by the American Smelting and Refining Co. According to the manufacturer their purity was 99.999 pct. The weighed amounts of the constituents were sealed in quartz tubes under an atmosphere of 10 torr helium, mixed for 24 hr in a rocking furnace at 380°C, quenched in ice water, and homogenized at 20" to 30°C below the solidus line, established by Heumann and Predel. The annealing times were 144 hr for specimens containing Less than 30 at. pct Pb and 36 hr for the remainder. 2) SUPERCONDUCTIVITY EXPERIMENTS The specimens were quenched from the homogeniza-tion treatment into ice water and their superconducting transition temperatures T, measured. The procedure used has been described in Ref. 4. The transition was detected by the change of the mutual induc- tance of two coaxial coils containing the sample. T, was defined as the temperature at which 50 pct of the total change in inductance had occurred. The repro-ducibility with which T, could be measured was i0.002"K. Then the specimens with lead contents between 38 and 75 at. pct were aged for 7 days at temperatures between -30" and 40°C. If this treatment caused T, to change by more than 0.005"K or the width of the transition to increase by more than 0.002"K, it was concluded that the specimen had undergone a phase change and no longer consisted only of the fcc lead phase: as it did immediately after homogenizing. The result is shown in Fig. 2. From this one can estimate at what temperatures and concentrations phase changes occur. The X-ray measurements were based on these preliminary results. 3) X-RAY EXPERIMENTS Because of the softness of the material, relatively coarse powders. 75 p, had to be used, which were filed in a helium atmosphere from homogenized specimens. The powders were annealed at least 30 min at temperatures between 120" and 16OJC, depending on their concentration, and quenched in ice water. Then their X-ray patterns were taken at -178°C with a Picker diffractometer, model 3488K, and a cold stage. on which the specimen was in thermal contact with a liquid-nitrogen reservoir. In this way the following relation was established for the fcc lead phase: a = 4.697 + 0.00247C for 40 5 C 5 75 11 where n is the lattice constant (A) and C is the at. pct of lead. The coarseness of the powder made it impossible to use lines with 0 > 75 deg; therefore n was averaged from lines with 45 deg 5 0 5 75 deg. The results were reproducible to within i0.05 pct. Relation [I] is very similar to the one found by Heumann and Predel at room temperature. Following this, homogenized specimens with compositions between 15 and 56 at. pct Pb were aged for at least 10 days at temperatures between -27" and

Jan 1, 1970

By Carl Scholz

DURING November And December, 1907, Four Serious Mine-explosions Occurred In The Appalachian Coal-Field, Which Resulted In The Loss Of Nearly A Thousand Lives And Caused An Enormous . Damage To Property. These Accidents Attracted More Than The Usual Attention; Coal-Trade And Engineering Papers Contained Many Comments And Suggestions On The Cause And Prevention Of Accidents; The Daily Press In Many Instances Condemned The Coal-Operators And Charged These Accidents To Their Negligence, Or Their Anxiety To Make Money Without Adopting Precautionary Measures. Immediately After Each Accident The Respective State ..Authorities Ordered Close Investigations To Be Made, With The View Of Establishing The Cause And Suggesting Remedies To Prevent Recurrence. Representatives Of The Technologic Branch Of The U. S. Geological Survey, To Whom The Investigation Of Mine-Accidents Had Recently Been Delegated By The Secretary Of The Interior,. Visited The Mines And Co-Operated With The Local Authorities In Their Determinations. It May Be Safe To Say Here That An Investigation Of A Mine After An Explosion Has Occurred Discloses But Little, Because. The Causes Have Been Removed And Conditions Have Been Entirely Changed. On Jan. 8, 1905, The Coal-Operators Of West Virginia Organized An Association At Washington For The Purpose Of Making Extensive Investigations, And Sufficient Funds Were Pledged To Carry Out This Work. At This Organization Meeting, The Representatives Of The Geological Survey Present Had No Suggestions To Offer As To The Cause Of These Accidents. An Examination Of The Various Reports Concerning These Accidents Indicates That The Explosions Were Caused By The Ignition Of Gas Or Dust; They Show The Point Of Origin And The Direction In Which The Force Was Expended, And Give A Detailed Description Of The Damage Done. Very Little Has Been Said As To What

Jan 7, 1908

By Markus A. Reuter, Bernardete Castro, Antoinette van Schaik, Han Remmerswaal

This paper describes the inseparable relation between product design, liberation, and metallurgical recovery in the optimisation of the recycling of passenger vehicles. This is illustrated by the use of an optimisation model that uses among others a material combination matrix based on metallurgical process data, which depicts the consequences of the quality of intermediate recycling products on the metallurgical material recovery and final alloy metal quality. Various simulations will illustrate the effect of changes in product design and hence liberation on the recycling of end-of-life vehicles. Although this paper focuses on cars, the discussion is equally valid for any end-of-life product. Calibration of the model will be discussed with reference to experiments carried out in order to study the optimal recovery of aluminium applications used in passenger vehicles.

Jan 1, 2003

By T. L. Joseph

The extent to which hot metal from the blast furnace affects open-hearth practice and the quality of steel produced has been discussed widely. Open-hearth operators have attributed difficulties experienced in making satisfactory steel to characteristics of the pig iron not disclosed by ordinary analysis. The commonest criticism of the iron has been that it is "physically cold" or "dirty." Often when the blast furnaces are working irregularly the quality of the iron is questioned. A cold hearth, slipping and hanging, the use in the past of unsintered flue dust, and the use of ores difficult to smelt have been associated with the production of iron of poor quality. The difficulty of the situation is that we have no proven yardstick for quality aside from ordinary analysis. Uniformity in analysis is recognized as being important, but the difficulty of changing the open-hearth practice when the iron analysis varies widely may not always be fully appreciated. Although the problem of correlating the characteristics of steel with those of pig iron is admittedly obscure, the effort of producers of quality steel to investigate all factors that may have a bearing on the final product is justified. This report contains data on the oxides in several hundred casts of basic iron produced in a furnace during the course of normal operation on Lake ores. Incidental to the study of the oxides in the iron, it was desirable to follow closely the temperature of the iron. The effect of temperature of the iron upon the silicon and sulphur present is discussed. A general relation between the basicity of the slag and the sulphur in the metal was developed. The amount and composition of oxides in the hot metal and in the steel bath during various intervals between melt-down and tap are discussed. Heats of rimmed steel, killed steel, and semikilled steel were investigated. The hot metal on individual heats was either all taken from a mixer or consisted partly of direct metal and partly of metal from the mixer. Samples of the iron for oxide determinations were

Jan 1, 1937

By W. W. Adams

Three hundred and twenty-eight mines and quarries, representing 36 States, took part in the twelfth yearly accident-prevention contest conducted by the United States Bureau of Mines and known as the National Safety Competition. Four underground mines and one open-cut mine (which represents the quarry and open-cut mine group), each the leader in its group, were awarded the ?Sentinels of Safety? trophy. Relative standing in the contest" was determined by the number of days lost from accidents in proportion to the total number of man-hours worked. Since 1925, when the National Safety Competition was inaugurated, an increasing interest has been taken in it by mining and quarrying companies as a means of stimulating mine and quarry safety by competition among similar plants. Each participating plant can, on a basis of its standing and record in the contest, determine to what extent its safety program is succeeding or to what extent it needs strengthening. With this information, each company that has a low standing in the contest can intensify its safety-promotion efforts the following year to obtain a lower rate and possibly win the trophy or achieve honorable mention in the competition. Except for 1929, the National Safety Competition of 1936 represented more man-hours of employment than any other year since the yearly contests began.

Jan 1, 1937

By G. Bonifazi

Mining activities belong to human history, they are lost in the mists of time. They usually impact on large portions of the territory, both directly (exploitation areas and logistic activities directly related to exploitation) and indirectly (exploited material handling, processing and storage areas). As a result, at the end of mine life cycle, dismissed areas usually cannot be directly re-utilized without efficient and well addressed rehabilitation actions. Main goal of the proposed approach was to analyze the results obtained when a set of procedures, based on the collection and the analysis of remote sensed data, is developed to evaluate the effect of rehabilitation of land contaminated by extractive industry activities and to perform a monitoring and registration of the environmental impact of such operations by the application and the integration of modern information technologies, as Earth Observation (EO) and Geographic Information Systems (GIS). The study was developed in the framework of the EU-Asia program of the European union (EXTRACT-IT Project-Contract No: CN/ASIA IT&C/006 (89870): Application of Information Technologies for the sustainable management of Extractive industry activities) and it was addressed to three different dismissed mine areas in India, Thailand and China, respectively. The results, in terms of methodologies selected, strategies applied and results obtained, are described with particular reference to Fuxin coal mine area in China.

Jan 1, 2014

By W. E. Oching, M. M. Ghomshei

Attracting and retaining workers in mining industry has become an uphill battle to many mining companies. As workers with significant experience retire, it is getting more difficult to attract not only new workers but also top talent to the mining industry to replace professionals exiting the workforce. To make matters worse, students’ enrolment in the post-secondary mining programs in Canada and USA is continuously declining year after year for reasons not directly linked to job market. This raises a question of how can the future needs of mining be met? This paper focuses on avenues for collaboration of industry and educational institutions to meet the current and future needs of mining. It provides effective approaches that mining institutes can engage with program advisory committees, role of the mining industry in supporting both faculty and students, how to harness the benefits of diverse workforce in the country and use of innovative technologies to attract young workers in mining. This work presents Human Resources (HR) professionals with tools that they can use to hire and retain skilled workers with strong interest to work in the mining industry. It also provides HR professionals with an opportunity to re-evaluate their restructuring practices during economic downturns as they reduce number of employees on temporary or permanent basis. The paper stresses the need of working together of the mining stakeholders including mining industry, academic institutions, First Nations’ communities and provincial(state) and federal governments to meet the current and future demands of mining as the industry experiences shortage of labour and low students’ enrolment in post-secondary mining programs. It is shown that mining educational institutes can enhance their programs and recruitments through establishing a better communication with all stakeholders. This communication can be facilitated by creating a national advisory board, to work with all mining programs at the national level for sustainable mining.

Jan 1, 2023

By James M. Barker

Sulfur is a nonmetallic element of great physical and economic importance to the world. It is widely but sparingly distributed throughout the hydrosphere, lithosphere, and biosphere. Sulfur is the tenth most abundant element in the universe and eighth most abundant in the sun. In the earth&apos;s crust, which is mainly igneous, it ranks 14th, but is eighth or ninth in sediments (Kaplan, 1972; Stanton, 1972). It apparently is very abundant in the core of the earth, because it is a strong chalcophile, and it is fifth in abundance in stony and iron meteorites (Field, 1972) where it occurs as trolite (FeS). In ancient times sulfur was called brimstone, literally "burning stone." Today the term brimstone is used interchangeably with the term elemental sulfur. Shelton (1979) summarized most of the common definitions of terms, grades, and specifications for the sulfur industry as follows (with minor additions): Sources of Sulfur: Combined sulfur-Sulfur that occurs in nature combined with other elements. Cupriferous pyrites-Pyrite containing relatively minor amounts of copper sulfide minerals. Hydrogen sulfide-A toxic gas (H2S) occurring in natural gas and petroleum. Involuntary sulfur-Sulfur produced primarily as a result of legislative or process mandates. Native sulfur-Sulfur that occurs in nature in the elemental (uncombined) form. Nonferrous metal sulfides-Copper, lead, zinc, nickel, and molybdenum sulfides that are processed for their metal content. Organic sulfurs-Complex organic sulfur compounds occurring in petroleum, coal, oil shale, and tar sands. Pyrites-Iron sulfide minerals that include pyrite, marcasite, and pyrrhotite. Sulfate sulfurs-Sulfur in anhydrite and gypsum. Voluntary sulfur-Sulfur produced in response to market forces. Basic Sulfur Products Produced and Marketed: Acid sludge-Contaminated sulfuric acid usually returned to acid plants for reconstitution. Brimstone-Synonymous with crude sulfur. Bright sulfur-Crude sulfur free of discoloring impurities and bright yellow in color. Broken sulfur-Solid crude sulfur crushed to -8 in. Byproduct sulfuric acid--Sulfuric acid produced as a byproduct of a metallurgical or industrial process, generally relating to combined sulfur sources. Crude sulfur-Commercial nomenclature for elemental sulfur. Dark sulfur-Crude sulfur discolored by minor quantities of hydrocarbons ranging up to 0.3 % carbon content. Elemental sulfur-Processed sulfur in the elemental form produced from native sulfur or combined sulfur sources, generally with a minimum sulfur content of 99.5%. Formed sulfur-Elemental sulfur cast or pressed into particular shapes to enhance handling and to suppress dust generation and moisture retention. Frasch sulfur-Elemental sulfur produced from native sulfur sources by the Frasch mining process. Hydrogen sulfide-Associated with natural gas or petroleum and produced at refineries and coke oven plants; used to make sulfuric acid or recovered sulfur. Liquid sulfur-Synonymous with molten sulfur. Liquid sulfur dioxide-Purified sulfur dioxide compressed to the liquid phase. Molten sulfur-Crude sulfur in the molten phase.

Jan 1, 1983

This report presents test results, data evaluations, and typical system performance expectations based on wireless electromagnetic propagation measurements performed in the MAGMA Copper Company&apos;s San Manuel mine near Tuscon, Arizona during March 30 through April 2 1981. In particular, and at the Bureau&apos;s request, this work was coordinated with testing of MF prototype vehicular radios being developed by A.R.F. Products, Inc. with USBM support under Contract H0308004 as part of a system to be marketed by Mine Safety Appliance Co. This testing also employed a prototype vehicular antenna developed by Terry S. Cory, P.E. with USBM upport under previous Contract P0382223. The work was performed under USBM contract J0308012, Propagation of EM Signals in Underground Metal/Non-metal Mines. The authors wish to thank Mr. Hank Seany, Manager of Mines and Mr. Bob Zerga, Mine Superintendent who so kindly arranged for the visit. Particular thanks are given to Mr. Al Metcalf who arranged the logistical details of our underground work, and whoa forward thinking program toward improving general mine communications at MAGMA provided the test-bed context for evaluation of the prototype equipment. The authors also wish to thank Benny Jiminez, Paul Ayala, Lorenzo De La Cruz, and Kent Billhartz for their day-by-day support of the testing. Mr. Jiminez&apos;s effort was instrumental in performing the testing, and he also provided a detailed understanding of the existing multi-level, multi-frequency trolleyphone system at MAGMA. the authors are also indebted to Dr. Larry Stolarczyk of A.R.F. for numerous detailed consultations on MF technology, and who was present and participated in the majority of the testing. 1.1 GENERAL BACKGROUND ON COPPER MINING AT MAGMA the San Manuel mine is the largest copper mine in the U.S., efficiently extracting copper and molybdenum sulfide from the low-grade San Manuel ore body.This ellipsoidal ore-shell body, with major workings located 2000-3000 feet mbelow the surface, has ore shell thickness varying between 100 and 1000 feet over a longitudinal extent of some 8000 feet, and with major & minor crossectional axes of about 5000 and 2500 feet respectively. The San Manuel mine operation employs in excess of 1000 men/shift with gross ore production between 60,000 and 70,000 tons/day. The mining operation employs the block caving technique; actively being implemented on three levels (2075,2375,2675 feet for haulage, and 2015,2315,2615 product/grizzly levels). The ore haulage is largely via D.C. trolley trains to four (3A,3B,3C,3D) product shafts for skipping to the surface. An additional three shafts at two locations are used to convey men, materials, and developmental rock extractions into and out of the mine. On each haulage level, the trains carry ore an average of two miles one-way from the ore raises to the dump points. 1.2 TOPOLOGICAL BRIEF OF THE HAULAGE LEVELS The 2375 level, on which all the testing was conducted, is illustrated in

Jan 1, 1981

By Michael S. Miller

The Carson-Iceberg RARE II study area, consisting o; 209,990 acres (134,983 ha), is on the crest of the Sierra Nevada in California, about 35 mi (56 km) south of Lake Tahoe. The area is divided into four parts: C4-986; C5-986; and B5-986, north and south portions. No mineral production has been recorded for the area. However, gold, silver, and tungsten resources and potential for additional resources have been estimated for the area and just north of area C4-986.

Jan 1, 1981

By Giulio Antunes de Medeiros, Leonardo Martins Silva, Giselle de Mattos Araújo, Rayla de Souza Caldas

To analyze the direct reduction of self-reducting briquettes producted with different electric arc furnace dust contents, three sets of homogeneous mixtures were produced with elephant grass biomass, iron ore, cement and furnace dust in increasing levels, which were submitted to thermogravimetric tests in muffle furnace and TGA furnace at variable temperatures and times. The curves of degree of reduction were obtained and the reduced briquettes were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results showed that the reducibility of the agglomerates is diminished by the increase of furnace dust, with variations of this result at higher temperatures. The observed microstructures were spherical particles, porous structure or whiskers. Based on XRD results, it was considered probable that the decrease of the degree of reduction with the increase of furnace dust content is related to the reaction between hematite and zincite, which is expected to be controlled by zinc diffusion.

Oct 1, 2019

By Clarence Hall, Spencer P. Howell

Among the more important factors involved in the use of high explosives in blasting operations is the means employed to bring about the detonation of the charge. When flame is applied to high explosives many of them may burn if not confined; but all of them when burning under certain conditions of confinement may detonate. Detonation may also be effected by mechanical means, such as frictional impact caused by a blow or by rubbing between surfaces. By this means, however, the full effect of the explosive charge may not be developed, so that a partial detonation, often accompanied by the burning of the explosive, results. When nitroglycerin was first used it was fired by the application of flame, but considerable difficulty was experienced in exploding it with certainty and in obtaining uniform resl'llts. In 1864 Allred Noble, a Swedish engineer, discovered that nitroglycerin could be surely and completely detonated by exploding in contact with it a small quantity of an initiatory explosive. Mercury fulminate was the substance then found capable of producing the best results There are many other fulminates and other substances that will produce complete detonation of commercial" high" explosives, but detonators or electric detonators containing mercury fulminate as the characteristic ingredient are still almost exclusively used in this country. The term" detonator" is used in the publications of the Bureau of Mines to designate what the miner calls a "blasting cap "-a copper capsule containing a small quantity of some detonating compound that is ignited by a fuse. The term" electric detonator" is applied to a blasting cap that is similar except for being ignited by means of a small wire which is heated to incandescence or fused by the passage of an electric current. One of the conditions prescribed by the Bureau of Mines for a permissible explosive a is that it shall be :fired by a detonator, or preferably an electric detonator, having a charge equivalent to that of the standard detonator used at the Pittsburgh testing station. A further requirement is that this charge shall consist by weight of 90 parts of mercury fulminate and 10 parts of potassium chlorate (or their equivalents). At the request of a manufacturer of permissible explosives, an investigation was undertaken by the bureau to determine the relative strength of detonators and electric detonators having different compositions. The tests of electric detonators herein reported were conducted by H. F. Braddock, junior chemist; J. W. Koster, J. E. Tiffany, junior mining engineers; and A. S. Crossfield, junior explosives chemist, at the Pittsburgh testing station of the bureau. Similar tests of detonators were not conducted because it was believed that the results would not show sufficient variation to warrant such tests. It is hoped that the conclusions drawn from the tests made will be of service to those using explosives by enabling them to select the grade of detonator or electric detonator that will insure the most effective results. The conclusions are given in this bulletin, which is published by the Bureau of Mines as one of a series of publications dealing with the testing of explosives and the precautions that should be taken to increase safety and efficiency in the use of explosives in mining operations. The results of tho experiments described in this bulletin show that the average percentage of failures of explosives to detonate was increased more than 20 per cent when the lower grades of electric detonators were used instead of No. 6 electric detonators, and was increased more than 50 per cent when these lower grades were used instead of No. 8 electric detonators. It is noteworthy, however, that when sensitive explosives, such as 40 per cent strength ammonia dynamite (p. 33), were tested under conditions ideal for detonation, the same energy was developed irrespective of the electric detonator used. When tests were made with a less sensitive explosive, such as a 40 per cent strength ammonia dynamite containing nitrosubstitution compounds (p. 32), the energy developed increased with the grade of the electric detonator used. For example, the average efficiency of four different explosives was increased 10.4 per cent when a No.6 electric detonator was used instead of a No.4 electric detonator, and 14.9 per cent when aN 0.8 electric detonator was used (see tabulation onp.45). The results of the tests emphasize the importance of using explosives in a fresh condition, but as fresh explosives can not always be had in mining work, strong detonators should be used in order to offset any deterioration of explosives from age.

Jan 1, 1913

By Thomas T., Read

THROUGHOUT the Colonial era, Philadelphia was easily , the leading city of North America, and it still held that position at the end of the period, with a population of about 25,000, though closely pressed by Boston, which had slightly over 20,000, and New York, which had nearly as many. It was the center of a region in which mineral industry was important. Thomas Rutter&apos;s bloomery, built in the Schuylkill valley in 1716, was quickly followed by many others, and during the Colonial period at least 20 blast furnaces, 45 forges, and iron- works of other types were built in eastern Pennsylvania, which easily led all the other colonies in iron manufacture. During the Revolutionary period others were erected as far west as Fort Loudon, in the Cumberland c alley.^ After 1800 the rapid development of the anthracite mining industry profoundly affected Philadelphia&apos;s, development, since transportation of the coal was then necessarily by water, and the streams of the anthracite . regions mostly flowed into either the Schuylkill or the Delaware Rivers. With an abundant near-by supply of coal and iron, with the seat of government, which had been there since 1774, and with a National Bank established there in 1791, one would have seemed safe in prophesying, at the beginning of the nineteenth century, that Philadelphia would permanently remain the leading city of the United States. Education in Philadelphia was at first wholly in the hands of the Quakers, who had established a "Public School" there in 1689, but in November 1739 George Whitefield, who had created a sensation in England by his preaching, though only 24 years old, passed through Philadelphia on his way to Georgia to found an orphan school there. He preached a series of sermons in Christ Church that were so disturbing to the established church that on Nov. 25 the Rev..Richard Peters (who was also Provincial

Jan 1, 1941