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By Albert C. Harding

For several years barite (BaSO4) production has topped such better known minerals as feldspar and fluorspar in annual tonnage and is now well established among our foremost nonmetallic industries. Description Of widespread occurrence in the United States, barite is relatively soft (hardness, 2.5 to 3.5), inert, heavy (specific gravity, 4.5), and is also called "barytes" (sometimes pronounced "bear-i-tease"), "heavy spar" and "tiff." It occurs with granular and earthy structure but usually has coarse, orthorhombic crystallization. It is commonly white, and although occurring in various shades of red, yellow, and gray, barite always gives a white streak and can be scratched by the ordinary prospecting pick. Its softness and weight are usually sufficient to establish field identification. Another aid is the "rotten egg" odor of H2S which sometimes emanates from freshly fractured surfaces. Barite can be readily distinguished from two other minerals which have somewhat similar occurrences and characteristics. The relatively rare celestite, strontium sulphate, has a specific gravity slightly less than 4.00 and gives a distinctively crimson color in a flame test. The very rare wither-ite, barium carbonate, has a specific gravity of 4.3 but readily effervesces with dilute hydrochloric acid. Occurrence All known commercially important barite deposits in the United States occur as re- placements or cavity fillings in schists, shales, limestones, dolomites, and quart-zites, or as residual deposits from such formations. In Georgia, Tennessee, North Carolina, and Missouri, high-grade barite is recovered as fragments from residual clays covering quartzites and dolomites. In Arkansas, Nevada, and California, barite, usually of lower grade, is mined from replacement deposits. These seven states contributed the entire production reported by the U. S. Bureau of Mines for 1945 as given in Table I. Table i—Crude Berile Sold or used by Producers in 1945 State Short Tons Arkansas................... 260.660 Missouri.................... 225.467 Georgia..................... 110,393 Tennessee................... 32,812 Nevada..................... 28,919 Other States............... 37,811 Total..................... 696,062 ('other states,, included only california and North Carolina. Such a large part of this undistributed production came from California that that state probably outranked both Nevada and Tennessee. For the second consecutive year Arkansas was the leading producing state, particularly worthy of note because there was no commercial production of barite there prior to 1941 and because the entire production of Arkansas has come from one large deposit which is being operated by two companies. Consumption The 1945 consumption as reported by the Bureau of Mines was: 482,442 tons as ground barite 139,288 tons in making lithopone 99,173 tons in producing barium ------- chemicals Total 720,903 tons

Jan 1, 1949

By E. M. Wise

THE practice of dentistry, particularly the construction of artificial dentures and "bridges," involves a unique and difficult application of the precious-metal alloys. Appliances used in the mouth are continuously exposed to corrosive agencies which can hardly be described as mild, and must remain free from tarnish and be substantially immune to corrosion. Limitations with respect to space and weight demand high physical properties, while complexity of form requires ease of working. The high corrosion resistance required necessitates the use of alloys of high precious metal content. The usual expedient of resorting to mechanical working to produce the requisite strength and stiffness cannot be utilized because of the frequency of annealing and soldering operations. To meet these difficult conditions manufacturers of dental goods were early led, unknowingly perhaps, to the production of precipitation-hardening or temperable alloys. The excellent properties of iridium-platinum may have suggested the addition of platinum metals to the conventional gold-silver-copper alloys to produce greater strength and hardness. It was found that such quarternary alloys retained their high physical properties after passing through the usual soldering process; i, e., heating to 7500 to 8000 C. and cooling naturally in the air. Later it was discovered that they could be softened and rendered more ductile by heating to the same temperature and quenching, in water. These early examples of precipitation hardening, for years the common knowledge, of dental practitioners and laboratory technicians, escaped the attention of the scientific world and discovery of the transformation which was responsible for this hardening was discovered by the Russian investigators of the system Au-Cu, Kurnakow, Schemtschushny and Zasedatelev,(1) § although the optimum conditions for securing good properties in aged alloys were not given attention.

Jan 1, 1932

By Allen G. Taylor

High-value materials, such as gold, platinum and other precious metals, are subject to loss through unauthorized removal from mines, smelters, refiners and other places where such materials are processed. A study by Gastrow (2001) determined that between 1994 and 1998 an average of 603 kg/a (1,330 lb/year) of gold was stolen from South African mines and subsequently recovered. This does not include the gold that was stolen but not recovered. At 2011 prices, 603 kg/a (1,330 lb/year) of gold would be worth approximately $33 million. Mine security personnel believe that the unrecovered stolen gold far exceeds what is recovered (Gastrow 2001). Traditionally, metal detectors have been used to screen personnel leaving secure areas to discourage such unauthorized removal. However, with the current near-record prices of gold, platinum and other precious metals, it has become worthwhile for people exiting a facility to walk out with quantities of product that are too small for ordinary metal detectors to register, resulting in substantial financial losses.

Jan 1, 2012

By Richard Hamburger

Calculating machines permit the use of the more rapid cotangent and semigraphic solutions of plane triangulation. The results of these methods are as accurate as those of other methods. Simple adjustment of the net, and ease of calculation encourage more complete field work. Errors in field work or in computation are easily localized.

Jan 1, 1950

By H. R. Hammond, E. Sadar

Cominco is making substantial savings in secondary breaking by replacing dynamite with a new nitrate-based explosive. Compareo with dynamite. the new explosive, known locally as "Fine NCN," is significantly cheaper, more effective and safer to use. It also works better than prilled NCN, which is unsatisfactory for secondary blasting because of inadequate sensitivity, low strength and awkward handling properties. A simple apparatus has been devised for pulverizing prilled NCN to a fineness practical for effective secondary breaking. Blasting systems using cheap detonating cord for initiation have been developed.

Jan 1, 1966

By George J. Skoronski

The economics of pellet plant operation, in terms of fuel and power consumption, flexibility in the selection of the cheapest fuel source, system availability, maintenance costs, and the simplicity of process design, contribute to the determination of building and profitably operating a pellet plant. Design innovations, sup- ported by actual field data, have been initiated into the GRATE-KILN System design to positively address these factors. This paper presents the recent state of the art design concepts which have helped the GRATE- KILN System assume worldwide acceptance status.

Jan 1, 1983

By Pedro C. Carneiro, Luiz G. I. Maciel

"This article presents data of advance and excavation rates in tunnelling works, and how theseactivities interact with the duration and cost of a contract. These key parameters, after analysis andsynthesis, will be used in coming works to ensure the evolution and adaptation of the method created by the Norwegian University of Science and Technology - the NTNU Method - to Brazilianconditions, which will be reflected in the duration and cost of underground drill and blast tunnellingworks."

Jan 1, 2016

Date of Congress: Sept. 20-25, 1915 The Committee on Local Affairs is fortunate in having secured for a period expiring on Oct. 17, an option. on 100 rooms at the Palace, St. Francis. and Fairmont hotels, the three leading hotels in San Francisco, with the distinct understanding that, on account of previous engagements whereby the hotels are reserved to their capacity, the rooms must be vacated on Sept. 25, 1915. The rates applying will be $7 per day for the court rooms occupied by two people, or $10 per clay for outside rooms occupied by two people. The outside rooms will face the main thoroughfares at the Palace and will face the city and bay at the Fairmont, which latter is situated oil a high hill. The St. Francis faces an open square and is flanked by main thoroughfares on two sides. If any members desire their reservation to extend either before the 20th or beyond the 25th, the Committee will use its best endeavors to secure such extension in individual cases, in accordance with the indicated wish. The Hotel Bureau in San Francisco is co-operating actively and closely with the. Committee on Local Affairs of the International Engineering Congress and offers the choicest rooms in any of 350 hotels other than the three mentioned above. This Hotel Bureau controls 50,000 rooms in San Francisco, which are all provided with hot and cold water, stationary basins, baths, house telephones, elevators, and bell boy service.

Jan 9, 1914

By A. van As, J. McGaughey, M. J. Mol, R. Tosen

Geotechnical monitoring is a key element of the successful management of a block cave mine. The interrelationships between production and various monitoring datasets are often not realized due to a lack of data integration and appropriate 3D visualization. Timely delivery of information to ensure best cave management practices is only possible with an integrated cave management system. At Rio Tinto, a state-of-the-art cave management system (CaveCAD) has been designed and developed in cooperation with Mira Geoscience to integrate and analyze vast datasets and report this as instructive information regarding the current \u201cstatus\u201d of the cave.

Jan 1, 2014

By William B. Conway

This paper will describe the large caisson pier foundations for four of the bridges crossing the Mississippi River in the New Orleans area; and will discuss some of the unusual problems encountered during their sinking. Certain settlement phenomena experienced during their service life will also be related: The four bridges in order of their construction: The Huey P. Long Bridge, River Mile 106.1, completed in 1935 The Greater New Orleans Bridge No.1, River Mile 96.0, completed in 1958 The Hale Boggs Bridge, River Mile 121.6, completed in 1983 The Greater New Orleans Bridge No.2, River Mile 96.1, completed in 1988 Each of these bridges employed large open-dredged concrete caissons as foundations for one or more of the river piers, with the smallest being the 65ft by 102ft caissons for Piers I and II of the Huey P. Long Bridge and the largest being the 99ft by 214ft caisson for Pier II of the Greater New Orleans Bridge No.2. The Huey P. Long caissons are founded in a dense fine sand at -170 while all of the other bridge caissons are founded in hard preconsolidated clay at elevations varying from -150 to -185. The Huey P. Long Bridge is currently being widened without increasing the caisson foundations under any of the river piers; and the design reasoning that led to this decision is presented.

May 11, 2007

By M. G. Mudrey

Considerable potential for metallic mineral resources in the lower Proterozoic rock of the Lake Superior region exists (Mudrey and Kalliokoski, in press). Most of the identified resources occur within a 2.0- to 1.9-b.y.-old lithotectonic assemblage characterized by extensive sedimentary strata in the north and thick volcanic se- quences in the south, all deposited on a two-terrane, composite basement of Archean age (DeMattis, 1989). Since the late 1960s, measured resources of nearly 90 Mt (100 million st) of typical volcanogenic massive sulfide at eight localities in Wisconsin have been discovered. The largest of these, near Crandon, contains about 61 Mt (67 million st) of ore averaging 5.6% zinc, 1.1 % copper, and 0.5% lead. Although none of these properties are in production, estimates by Mudrey (1978) suggest that Wisconsin could become a major contributor of newly mined zinc and copper in the United States. These discoveries and uranium and gold discoveries in the Canadian Precambrian are what have led to in- creased metallic mineral exploration throughout the northern half of Wisconsin (Fig. 1). In this chapter, we discuss the geology and legal framework in which the Proterozoic volcanogenic massive sulfide deposits were found. Exploration activities for other metals have generally been negative, and have been background noise for the legislative activities related to the massive sulfide discoveries. Uranium exploration has been consistently negative, although several different environments have been assessed. Other metal discoveries. such as titanium/vanadium, have been subeconomic.

Jan 1, 1991

By J Col, D La Rosa, W Valery, A Jankovic

Metso Minerals Process Technology Asia-Pacific and South America (MMPT) has been working with operations around the world to increase their efficiency through æMine-to-MillÆ or Process Integration and Optimisation (PIO) projects. These projects have delivered significant improvements in mine efficiency, mill throughput and reduced operating costs at mines around the world. The MMPT methodology involves rock characterisation, site auditing, data collection, modelling/simulation and implementation of integrated operating and control strategies on site. This results in significant benefits to the operations û for example, 5 to 20 per cent increases in concentrator throughput have been measured. MMPTÆs rock characterisation utilises simple and inexpensive measurements that can be performed by trained site personnel. The advantage of these measurements is that a large amount of data can be collected in a very short timeframe, as the samples do not require shipping to an outside laboratory. Typically, a PIO project starts with a site visit to perform blasting and process audits, collect high quality data including measurements of run-of-mine fragmentation and survey data around all crushing and grinding circuits. These measurements are combined with rock characterisation and the definition of strength and structure domains to model the complete production chain. Site-specific models of the blast fragmentation, crushing, grinding and flotation processes can then be developed. This proven methodology has applications ranging from greenfield projects to long-standing operations with AG/SAG or conventional grinding circuits. Process improvements can be higher mining productivity, higher mill throughput, decreased overall operating costs and higher flotation or leach recovery. This paper discusses a recent application of PIO conducted at a large open pit operation in South America and emphasises the potential that every operation has to ædo more with what they haveÆ.

Jan 1, 2007

By R. Hoare

TSG Consulting works with many of the major global mining companies using simulation modelling as an integral component in their development team's processes to determine which combination of infrastructure options, operating performance and operating rules best achieve project goals. All systems can be divided into a series of subprocesses. Conventional management and design practices focus on the optimisation of these system components. However, the interaction between subprocesses means that improvements made to the individual components do not necessarily translate into total system performance improvement. TSG Consulting advocates a `total integrated system approach' to understanding the behaviour and performance of complex interacting systems. In a constraint-based integrated set of processes, the instantaneous system capacity is limited by the subsystem component capacity that is the bottleneck at that point in time. Additionally, real world stochastic and dynamic influences tend to have knock-on effects across subsystem boundaries. This necessitates the requirement for simulation modelling to develop and validate solutions that are sufficiently robust to deliver sustainable outcomes. The key to maximising production is to understand the causes and effects the inherent variability has on component performance, subprocess performance and most importantly, the total integrated system performance. The correct use of simulation modelling techniques allows study teams to evaluate the relative merits of different capacity enhancement proposals. Put simply, when done well, simulation modelling provides a quantitative and rational process to enhance the knowledge and insight needed to make informed decisions.

Jan 1, 2007

By H. T. Clark, H. K. Work

The instrument for the rapid determination of carbon in steel, described in this paper, was developed originally to facilitate the operation of the pilot-sized open-hearth furnace in the Jones & Laughlin Research and Eevelopment Laboratory. In this small furnace, with its shallow bath, the drop in carbon is accelerated, and a rapid, reliable test for carbon content is indispensable. This problem becomes rather acute when it is desired to finish heats at a carbon content higher than can be estimated with any degree of accuracy by the fracture test. Several independent methods for determining carbon were investigated, therefore, and it was found that a relatively simple magnetic device could be made to give reproducible results. A laboratory instrument was designed and set up for the use of the furnace operators. It was tested exhaustively in the laboratory and was used with considerable success for following the carbon content in the furnace bath. As soon as sufficient data had been compiled to indicate that the instrument might have a wider application, a more rugged model was constructed and placed in the mill to be tested on commercial heats. Finally, about a year ago, instruments were furnished to the plant open-hearth shops, and these have been in use since that time. As a matter of convenience, the instrument has been named the "Carbanalyzer," and will be referred to by this designation in the following pages. $ Eaklier Investigations While by far the greatest number of magnetic investigations in which the carbon content of ferromagnetic materials was considered have had to do with the evaluation of the magnetic properties of steels of known

Jan 1, 1940

By W. Wittke, D. Schröder, H. Polczyk

ABSTRACT: The Urft dam, the Diemel dam and the Eder dam are three old masonry damslocated in Germany. The paper describes the rehabilitation measures and the correspondingstability analyses carried out to adjust the dams to today's standards. Remedial works such as theexcavation of inspection galleries, the installation of a grout curtain with a downstream drainagescreen as well as the installation of pre-stressed permanent tendons were carried out. In all threecases the stability of the upgraded dam could be proven on the basis of finite element analyses. ZUSAMMENFASSUNG: Die Urft-, Diemel- und Edertalsperre sind drei alte deutscheSchwergewichtsmauern aus Bruchsteinmauerwerk. Im Beitrag werden Instandsetzungsmaß-nahmen und Standsicherheitsnachweise beschrieben, die erforderlich waren, um die Staumauernan den heutigen Stand der Technik anzupassen. Hierzu wurden Kontrollgänge aufgefahren,Dichtungsschleier mit luftseitiger Dränage sowie vorgespannte Daueranker hergestellt. In allendrei Fällen konnte unter Berücksichtigung der Instandsetzungsmaßnahmen die Standsicherheit derMauer auf der Grundlage von Berechnungen nach der Methode der finiten Elemente nachgewiesenwerden. RÉSUMÉ: Les barrages de Urft, Diemel et Eder sont trois barrages-poids vieux allemandsconstruit de maçonnerie de moellon. Dans cet article, opérations de remise en état et preuves destabilité sont décrits, qui étaient nécessaires pour adapter les barrages à l'état de la techniqueactuelle. À cet effet, des galeries de contrôle étaient creusés, voiles d'étanchéité avec des drains àla face aval et tirants précontraints permanents étaient fabriqués. Dans tous les trois cas, tenantcompte des opérations de remise en état, la stabilité de la barrage pouvait être prouvée à partir decalculs selon la méthode des éléments finis.

Jan 1, 2003

By H. K. Work, H. T. Clark

The instrument for the rapid determination of carbon in steel, described in this paper, was developed originally to facilitate the operation of the pilot-sized open-hearth furnace in the Jones & Laughlin Research and Eevelopment Laboratory. In this small furnace, with its shallow bath, the drop in carbon is accelerated, and a rapid, reliable test for carbon content is indispensable. This problem becomes rather acute when it is desired to finish heats at a carbon content higher than can be estimated with any degree of accuracy by the fracture test. Several independent methods for determining carbon were investigated, therefore, and it was found that a relatively simple magnetic device could be made to give reproducible results. A laboratory instrument was designed and set up for the use of the furnace operators. It was tested exhaustively in the laboratory and was used with considerable success for following the carbon content in the furnace bath. As soon as sufficient data had been compiled to indicate that the instrument might have a wider application, a more rugged model was constructed and placed in the mill to be tested on commercial heats. Finally, about a year ago, instruments were furnished to the plant open-hearth shops, and these have been in use since that time. As a matter of convenience, the instrument has been named the "Carbanalyzer," and will be referred to by this designation in the following pages. $ Eaklier Investigations While by far the greatest number of magnetic investigations in which the carbon content of ferromagnetic materials was considered have had to do with the evaluation of the magnetic properties of steels of known

Jan 1, 1940

By Krokhmai VS, Sayko OP

The paper summarises the theoretical and experimental studies which led to the development of new industrial equipment designed to recover liberated gold from placer gravity concentrates. The new technology is based on environmentally clean magnetic methods, which avoids use of mercury in the production process and obtains higher gold recoveries compared to the amalgamation technique, and which can reach 98.6 - 99.5 per cent. The complex of equipment thus developed is now commercially used at nine Russian gold mining operations. Six more such complexes are due to come on stream in 1993, some of them outside the CIS. The new technology appears to hold much promise for the recovery of precious stones (diamonds, rubies etc) semi-precious stones (pyropes, chrysolites etc) and also artificial diamonds, for which case there are encouraging laboratory results.

Jan 1, 1993

By Thomas T., Read

IN this survey of the progressive development (of education for the mineral industries throughout the United States, the review of .the history of each school has usually been completed wherever it is first mentioned, but the history of the schools in the cities of the eastern seaboard was not carried beyond 1870. It is necessary now to cover what happened during the period of approximately the last quarter of the nineteenth century in several of the schools in the east. Philadelphia Of Philadelphia, it has been related in chapter 4 that the Polytechnic College of Pennsylvania began offering a curriculum leading to the B.S. in mining in 1853; that the school did not prosper, and finally closed about 1890. The establishment of a Department of Mining, Arts, and Manufactures at the University of Pennsylvania in 1855-56 was also mentioned, but its history was not carried beyond 1860. In 1859 J. Peter Lesley was appointed professor of mining in the University of Pennsylvania. The son of a cabinetmaker, born in Philadelphia Sept. 17, 1819, he had taken his A.B. degree at the University of Pennsylvania in 1838 and then secured a position on the Geological Survey of Pennsylvania under H. D. Rogers. When the Survey was discontinued, in 1841, he went to Princeton to study theology, was ordained a Presbyterian minister and followed that career until 1852, when the Pennsylvania, Geological Survey was again started and he rejoined its staff. He published "A Manual of Coal and its Topography" in 1856, and studied at the École des Mines, Paris, in 1856-57. He published an 800-page "Iron Manufactures Guide" the year that he was appointed to the staff at the University of Pennsylvania. In 1863-64 a College of Agriculture, Mines, Arts and the Mechanic Arts was established, but it was not a separate school

Jan 1, 1941

By A. B. Kinzel

PRECISE knowledge regarding the effect of heat treatment on the properties of steel has made possible the detailed specifications and instructions covering optimum heat-treating temperatures and practices that are in current use. A distinct contrast is presented by the metallurgical treatment of steel adjacent to a fusion weld, as such steel is subjected to each temperature from room temperature to fusion temperature, and cooled at a rate that is not generally controllable but is predetermined by the nature of the assembly to be welded, the kind of welding used, and the surrounding conditions. This is true regardless of the type of fusion welding: oxyacetylene, electric arc, thermit or flash resistance. Therefore it seemed desirable to investigate the effect of this metallurgical treatment on the characteristics of carbon steels commonly used for welding, by a detailed study of metal subjected to each temperature range; i.e., each heat-affected zone. Oxyacetylene welding was chosen for the investigation because of the experimental facility of accurately segregating and studying each temperature zone. The nature of the zones produced by other types of welding is the sane. The difference is primarily a matter of dimensions of each of the temperature zones involved. The advantages and disadvantages of the extent of the zone are of prime moment, and are discussed after the presentation of the detailed zone study. No mention is made of the fused metal proper, as this has been the subject of much published research and the nature of the solidified metal is fairly well known. GENERAL METHOD The scheme of procedure in the work herein reported involved the testing of the metal of each temperature zone adjacent to the weld in so

Jan 1, 1935

By William E. Cobb

15.1 INTRODUCTION The mine development process, as discussed in Chapter 2, is a series of data gathering and analysis steps. As the mine development process proceeds, information about the geology, mineability, and metallurgy of a particular deposit is continually generated, along with environmental information regarding project permitting status. As data are obtained, checkpoint evaluations are typically conducted to determine the economic viability of the particular deposit. Although the project evaluation process was discussed at length in Chapter 2, a brief review of the process is presented here to "set the stage" for the discussion on economic analysis of heap leach projects. Figure 15.1 (MacKenzie, 1980) presents an overview of the sequential process of mine development. Once the deposit is discovered or acquired, an initial delineation program can be undertaken to expand the project's geologic, mining, and metallurgical data base. At the end of this initial program, the direction of the project is evaluated. The company can either abandon the project, postpone it, develop and mine it, or gather additional data in hopes of improving the project's economic viability. If the company continues gathering data, then another decision point and evaluation will be required. This process may continue until the company either decides to postpone the project or develop and mine it. A project may be postponed indefinitely, typically in hopes of improved metals prices. Certain holding costs, such as land or royalty payments, may be associated with postponement. In general, once a company goes through two evaluations, the project is less likely to be abandoned. For this discussion, it is assumed that the company will undertake initial, second, and third delineation programs to gather sufficient geologic, mining, metallurgical , and environmental data to justify a positive production decision from the second or third economic evaluation. The objectives of the first delineation program will be to confirm and expand upon the available information about the deposit. During the second delineation program, development funds should be directed toward identifying the critical project items (i .e., ore reserves, mineralogy, mineable grade, metallurgical recovery, etc.) that must be resolved before making the production decision. This second economic evaluation can be used to determine which metallurgical concept will be applied to the project: heap leach or a traditional agitation-type leach plant. If the proper work has solved key project concerns in the second program, a production decision may be made from that evaluation.

Jan 1, 1988