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By E. I. Larsen, E. F. Swazy, F. R. Hensel

HIGH strength, high-conductivity copper-base alloys have found considerable use in the resistance welding and electrical industry in the form of castings, forgings, or wrought products. There are a number of parts utilized by these industries which would lend themselves to manufacture by powder metallurgical methods provided the required physical and electrical properties are obtainable with such methods. The present paper describes the results of a study of certain copper-base powder metallurgical products susceptible to precipitation hardening. COPPER POWDERS The general types of commercially available copper powders are flake, spherical and electrolytic. Micrographs of these three types are shown in Figs. I, 2 and 3. The difference in particle shape is pronounced and obvious. The type of powder used is determined, or at least indicated, by the final properties desired in the finished article. The type of powder employed during the present investigation was electrolytic powder shown in Fig. 3, and was chosen because of its particular adaptability to the work described in this paper. The screen and chemical analyses of this powder are shown in Table I. In the preparation of compacts of high electrical conductivity, the purity of the copper powder is of importance in addition to other factors, such as density and the state of internal stresses. These variables were studied briefly by pressing a number of compacts to various pressed densities, sintering them for one hour in hydrogen at 975°C. and repressing. The size of the finished compacts was ¼ by ¾ by 8 in. The time interval from the application to the termination of pressure was approximately 20 sec. Some of the compacts were annealed before testing. The results are listed in Figs. 4 to 8, inclusive. [ ] In Fig. 4 the curves of pressed density vs. compacting pressure, and sintered density versus compacting pressure show the typical direct relationship of pressure and density. Compacting pressures exceeding about 30 tons per sq. in. result frequently in expansion during sintering for the type of powder used. Fig 5. indicates that variations in the initial pressed density within the range of about 5 to 6 grams per c. c., affect only slightly the pressure required to obtain a

Jan 1, 1945

By Jos. R. Guiteras

This paper is one of a series describing; mining and milling methods and costs being published by the Bureau of Mines. It deals with the mineral resources of western South Dakota and describes the mining and milling of tantalite and associated amblygonite by the Black Hills Tin Co. and the Fansteel Mining Corporation. ACKNOWLEDMENTS Acknowledgment is made to Earl C. Schultz and Arthur I. Johnson, respectively superintendent and engineer for both the Black Hills Tin Co. and the Fansteel Mining Corporation, who contributed the information on mining and milling operations.

Jan 1, 1939

By H. R. Manouchehri

The importance of the grinding environment and its effect on sulphide minerals flotation behavior has been known for many years. The grinding environment may play a role in controlling fine and coarse particle flotation along with dissociation of different chemical species in grinding environment. Dissociation of different chemical species and ions within the process water may result from changing the grinding environment. The mining and mineral processing industry undertakes activities that may impact on water resources. These include use and storage of chemical storm-water management, process water management, mine dewatering and management of tailings. In mineral flotation understanding and controlling water quality is paramount important not only because of its effect on flotation but also with respect to control the quality of the water which is released to the environment. Releasing of different anionic and/or cationic chemical species in the process water results from the interactions among different mineral within the ore, process water, and the milling environment. In fact grinding mill acts as an electrochemical reactor which affects the flotation performances of different value minerals as well as the quality of the tailing products. An increasing in antimony content in process/discharge water at Boliden?s Tara processing plant in Ireland to above limitation level was reported in April 2010 which needed to be controlled. An increase up to 6 times of the permitted level was reported which needed an immediate action to control due to environmental considerations. Therefore attempts were made to detect why this higher amount of Sb is released and how to control and minimize its release to the process/reclaim water. This paper discusses how/why Sb content in process/reclaim water was increased by changing the mill electrochemistry and the strategies were taken into considerations to control it. Different strategies, including electrochemical controlling of the milling section, Fenton process, using Bauxsol in treating the process water, etc., have been considered and tested which are described herein. All strategies taken into consideration for solving the problem were successful which indicated good understanding of the issue and good decision making. Furthermore, for each solution the capital and operational costs were roughly estimated. Accordingly, the Sb content in process/discharge water was controlled to a value lower than allowed limitation, i.e., 1 ppm. Keywords: antimony, water contamination, mill electrochemistry, ag milling, grinding media, eh-ph, sulfide minerals, fenton process, bauxsol, lime addition

Sep 1, 2012

By Mirjana Boskovic

LKAB’s Kiirunavaara Mine is a sublevel caving iron-ore mine located above the polar circle in northern Sweden. The mine has been proclaimed seismically active since 2008 after a magnitude 3 seismic event, according to Swedish National Seismic Network (SNSN). At that time the Kiruna Mine did not have mine-wide seismic system. Since then, the Kiruna Mine experienced several damaging seismic events of which the largest one on the May 18, 2020. The magnitude, based on the moment tensor inversion results on data from the SNSN as well as seismic stations in Finland and Norway, is estimated to 4.2 ± 0.2 moment magnitude. The seismic event on the May 18, 2020 was located in the middle of the one of the productions areas and caused the major damage in the mine, damaging several kilometres of drifts on six mining levels, some of them beyond the practical repair. These damages affected four of ten production areas on several levels, some more some less. Luckily, no person got injured from the seismic event and the very long aftershock series. An important part in the whole process after the seismic event was information flow and decision-making process. It was very important to keep workers and community informed as that contributed transparency of decision-making and decreased the speculations. Resuming the production in the damaged areas in the safe manner, very soon become main focus for the mine management. It was obvious that not only rehabilitation of the areas is needed to resume the production. It was A MUST to understand the factors behind the seismic event and its mechanism to be able to avoid same situation and prevent seismic event of similar size. Mine engineers had to think outside the box to find the solutions to ‘rescue’ every drift that they could to be able to make good enough base for continued mining of the area. The paper describes actions taken in a very complex process of recovering the area that we from the beginning thought need to be abandon. Seismological analyses of the event on May 18, 2020 and past activity in the area, damage mapping, detailed studies of structures and geology, numerical modelling as well as engineering judgement were used as base for all our decisions how to proceed in attempt to restore mining of the area heavily damaged by 4.2 moment magnitude seismic event, in a safe way.

Apr 26, 2022

By Albert W. Cox

This paper, one of a series prepared for the United States Bureau of Mines discussing the methods used in mining, crushing, and grinding materials for cement manufacture, deals particularly with the methods used at the Security plant of the North American Cement Corporation. These papers are designed to disseminate technical information regarding the methods used. The cost tabulations represent local operating expenditures only and not total production costs. It is recognized that publication of, total production costs might in many instances cause embarrassment to individual producers as well as to the industry as a whole. On the other hand, operating costs are essential to the technical discussion and study of methods employed. The attention of the reader is specifically called to this differentiation in order that no misunderstanding of the scone of the cost tabulations shall ensue.

Jan 1, 1932

By C. W. Schultz

The vapor pressure of manganese in equilibrium with a series of liquid iron-manganese alloys was determined by the carrier gas method over a broad range of alloy composition. From these data the activities of manganese in the iron-manganese system were calculated. The system appears to be ideal.

Jan 1, 1966

By Pedro P. Olórtegui F

El presente texto revisa desde 1952 las actividades de Higiene industrial en relación con la Cerro de Pasco Corporation, describe las condiciones ambientales introducidas en la aplicación de la ventilación exhaustiva en las plantas del circuito de fundición de plomo y visualiza las posibles soluciones de Higiene industrial aplicadas a las secciones del circuito de plomo de nuestra fundición. El programa de Higiene industrial de Cerro de Pasco se encuentra en una etapa de evolución donde evalúa el uso de técnicas modernas y los riesgos de las operaciones que puedan representar para la vida de sus trabajadores. En este sentido, se muestra la interdependencia entre el campo de la prevención de accidentes y la aplicación de los principios de Ingeniería de Higiene industrial, lográndose reducir los niveles de contaminación del plomo y la prevalencia de las enfermedades profesionales a través de una campaña de orden y limpieza efectuada por la sección de Higiene industrial.

Aug 20, 1965

"Many industrial processes involve materials that are subject to temperature change and thermal stress. Examples range from the casting of large metallic products to the cooling and reliability of small electronic components. Thermally induced stress is a major concern as it can lead to material damage and product failure. Material properties, thermal and mechanical, and process conditions such as the size and location of a feeder in metals casting, or the power dissipation in a computer chip, will govern the magnitude of these stresses. Temperature may also be influenced by fluid flow, for example, the airflow over a computer chip in a laptop will govern the rate of heat extraction, hence the temperature gradients in the chip and the evolving thermal stresses.This paper provides details on the governing equations for heat transfer (temperature) and solid mechanics (stress), their degree of coupling, and the numerical techniques used to solve them. Three examples are discussed to illustrate the use thermomechanical modelling. These also provide an insight into the degree of coupling required between the equations. The first example, involves thermal cycling of electronic components where a prescribed temperature field is applied. As temperature is known, this example only requires the solution of the stress equation. The second example also involves the modelling of an electronic component where the temperature field is also calculated. In both of these examples, the stress calculation is dependent on the temperature field, but the temperature calculation is not dependent of the solution of the stress equation (one-way coupling). The final example provides details on modelling the metals casting process. Both the temperature and stress equations are solved but, unlike the previous two examples, in this case the temperature field is dependent on the results from the stress calculation (two-way coupling)."

Jan 1, 2001

By John W. Taber

"INTRODUCTION AND SUMMARYDiscovery of these unusual fluorite deposits was brought to the attention of the Bureau of Mines late in 1951, shortly after the first locations were made. A brief investigation of the deposits by the Bureau revealed seven principal outcrops of fluorite in two areas. The smallest outcrop continuously exposes massive fluorite over an area 25 by 55 feet; the largest outcrop is a similar exposure 180 by 240 feet. The deposits, appear to be sharp-walled, low-angle, tabular ore bodies in granite and are at least 10 feet thick.The Bureau investigation of the deposits included bulldozer strip-trenching, drilling and blasting rock cuts, and channel sampling across three of the largest outcrops. This sampling indicated an average grade of 97.2 percent CaFp and 1.44 percent SiO2.Preliminary metallurgical tests on the ore indicate that it can be concentrated to acid-grade specifications by simple gravity methods. One laboratory test recovered 78.4 percent of the fluorite in a product containing 98.7 percent CaF2, 0.25 percent SiO2, and 0.10 percent Fe2O3."

Oct 1, 1952

By Willard L. Cumings, Benjamin L. Miller

(Glen Summit Meeting, June, 1911.) I. THE CAMAGUEY DEPOSITS. 1. Location. THE Camaguey brown iron-ore deposit covers the top of San Felipe hill, the nearest point of which lies 14 miles NW. of the city of Camaguey. While there are several low flat-topped hills in the vicinity covered with a more or less continuous mantle of brown iron-ore, the deposit of San Felipe hill is the only one of any size and importance, and the name "San Felipe district " is proposed for the region. The deposit extends in a NW-SE. direction for a distance of about 10 miles, with an average width of 5 miles. The location is shown in Fig. 1, a sketch-map of the eastern part of Cuba. Fig. 2 is a map of the San Felipe district. 2. Description. The district is mentioned by Spencer,1 who says: "The Cubitas iron-ore fields are situated from 12 to 15 miles north of Camaguey City, in the province of Camaguey Within an area measuring roughly 10 miles east and west and 4 miles north and south, there are several flat-topped mesas rising 300 to 400 ft. above the level of an almost featureless plain which extends for many miles in all directions except toward the north." With the exception of the discrepancy in his statements as to the distance from Camaguey and the area of the hill, which is over 50 sq. miles, his description is a very good one. Kemp 2 has the following to say of ores in Carnaguey Province * Geologist, Bethlehem Steel Co. + Professor of Geology, Lehigh University. 1 Bulletin No. 540, U. S. Geological Survey, p. 324 (1908). 2 The Iron Ore Resources of the World, printed by the Eleventh International Geological Congress, vol. ii., p. 795 (1910).

Mar 1, 1911

By G. Barbery

The models for particle composition prediction that have been put forward are limited to simple textures and lead to an independance of grade with respect to particle size in broken ore. A presentation is made of a modification in texture description; binary textures, in which each subeonstituent has its own breakage characteristics are introduced. The calibration of the textural model can be made using heavy liquid separation results. The application to the case of coal is presented. Coal washability data present spe¬cial difficulty due to the distribution in the specific gravity of coal, which must be taken into account. Coal s.g. distribution is taken as a generalized exponential distribution. Model calibration is then possible and is shown to be in good agreement with experimental data.

Jan 1, 1987

By Edmund Shaw

This paper is one of a series being prepared by the United states Bureau of Mines describing mining and milling methods and costs at industrial mineral plants throughout the United states. These papers are designed to disseminate technical information regarding the methods and equipment used. The cost tabulations represent operating expenditures only and not total production costs. It is recognized that publication of total production costs might, in many instances, cause embarrassment to individual producers as well as to the industry as a whole. On the other hand, operating costs are essential to the technical discussion and study of the methods employed. The attention' of the reader? is specifically called to this differentiation in order that no misunderstanding of the scope of the cost tabulations shall ensue. P. J. Weisel, Inc., with office at La Habra and plant at Corona, Calif., is the only local company that produces sand for the Los Angeles glass factories, although silica sand for other purposes is produced in other parts of southern California and the adjacent portions of Nevada. The deposit at Corona consists of coarse sand imbedded in a whitish clay and differs greatly from the other deposits, which are fine-grained sandstone that must be crushed before it can be screened and washed. The preparation of Corona sand has to be thorough and includes grinding in tube mills, repeated washing and rinsing, removal of dust by air separation, and magnetic separation of iron and other minerals. This requires a plant with a complicated flow sheet. The first plant built did not make a. satisfactory glass sand, and many additions and changes were necessary. It is thought that the present flow sheet will remain substantially unchanged until a new plant is built. The design of a new plant would be simpler, but the process would be the same.

Jan 1, 1937

By G. R. Rubly, H. J. Steele

LOCATION AND HISTORY THE San Manuel property is in townships 8S and 9S, range 16E, Gila and Salt River Base and Meridan, State of Arizona. This area is in the Old Hat mining district, southern Pinal County, and is about 3;2 miles southwest of the town of Mammoth on the San Pedro River and one mile south of the Mammoth mine at Tiger, Arizona. The property consists of over 150 contiguous lode claims. The Old Hat district was prospected prior to the Civil War, but there was little or no production until 1881.1 The chief producers have been the Mammoth and Mohawk mines, now consolidated and operating as the St. Anthony Mining and Development Co., Ltd. Production to 1936 was $5,200,000, of which 83 pet was gold.2 Since 1940 the production has been chiefly lead and zinc, and some molybdenum and vanadium. There are a few small properties in the vicinity that have produced very minor tonnages of copper ore. In the San Manuel group there are claims which have been held continuously from 1906 to the present time, and at least two churn-drill holes were put down on or near the outcrop in 1917. No logs for these holes are available, but it is assumed that the grade of copper encountered was not sufficient to encourage further exploration. A small amount of ore has been shipped from open cuts on the San Manuel outcrop area, but there is no record of the tonnage or grade. It is estimated that not more than 5o tons were mined. These cuts, plus a few shallow shafts and some short adits indicate limited and unenthusiastic prospecting at San Manuel. In 1942, through the efforts of James M. Douglas, R. B. Giffin, Victor Erickson, and Henry W. Nichols, owners of the San Manuel group, the Reconstruction Finance Corporation and War Production Board authorized the United States Geological Survey to investigate the property, and by their recommendation, the United States Bureau of Mines was authorized to put down a limited number of churn-drill holes. The Bureau of Mines carried on drilling from November 1943 to February 1945. Seventeen holes were drilled, varying from 305 to 1990 ft in depth. The property was brought to the attention of Magma Copper Co. in June I944 and an option agreement was made with the owners. Subsequently, a group of claims lying north of the original group and held by the Apex Lead Vanadium Mining Corp., and a group to the east held by the Quarelli family, were optioned. A drilling program was laid out to conform to the Bureau of Mines pattern, and drilling started in December 1944. San Manuel Copper Corp. was incorporated September 1945, and has carried on the exploration program to the present time. GEOLOGY General The mineralized outcrop, chief copper mineral of which is chrysocolla, is a tri-

Jan 1, 1947

By Edward R. Rose

This paper summarizes and emphasizes the potential importance of Canadian rare-earth occurrences, and recommends that efforts to locate and evaluate rare-earth deposits should be increased. Increasing world markets, depending on intensive applied research into the numerous unique and remarkable chemical and physical properties of the rare-earth elements (REE), are developing; their properties and uses are becoming better known; methods of separation are much improved. The REE group comprises a Cerium (Light) subgroup of 7 metals and an Yttrium (Heavy) subgroup of 9 metals. REE are trace elements in many rocks and minerals, and major constituents of more than 50 rare-earth minerals, many of which are difficult to detect and identify. They occur preferentially in acidic and alkaline igneous and metamorphic rocks, including carbonatites, as well as in placer deposits, certain uranium deposits, phosphate rocks and others. The main ores now are bastnaesite (in Precambrian carbonatite), monazite and xenotime (in Recent beach sands) as well as uraninite and brannerite (in Huronian quartz-pebble conglomerate) and loperite (perovskite) and apatite (in alkaline complexes). World resources are summarized. Twenty mines in 1973 produced an estimated world total of about 31,000 tons of contained rare-earth oxides (REO), 19,341 tons of which came from one mine at Mountain Pass, California. A selected fifteen, of 315 or more Canadian occurrences, are briefly described and compared, and their relative merits indicated. Their abundance and variety suggest the possibility of finding high-grade deposits in many geological terranes in Canada.

Jan 1, 1979

By Milson de Andrade Júnior

A Central Termoelétrica número 2 (CTE#2) possui três caldeiras de alta pressão que utilizam principalmente os combustíveis residuais dos processos siderúrgicos, com destaque para o gás de alto-forno (GAF), o qual está disponível em grande volume e com baixo custo. Como o GAF possui baixo valor calorífico, ele é enriquecido em duas misturadoras com gás de aciaria (GLD) e na ausência ou limitação deste, com gás natural (GN). A partir de 2014, devido a problemas com o gasômetro de GLD, passou-se a utilizar o GN com frequência para fazer o enriquecimento do GAF, o que gerava significativo impacto no custo do vapor devido o alto custo do GN. O sistema de injeção de GN nas misturadoras era controlado de forma manual e praticamente não acompanhava as variações no poder calorífico (PCI) do GAF. Percebeu-se que seria possível implementar um sistema de controle para as injeções que levasse em consideração o PCI do GAF, reduzindo o consumo de GN quando o PCI estivesse mais alto e aumentando o consumo quando o PCI estivesse mais baixo. Após a implementação deste sistema houve uma significativa redução no consumo médio de gás natural para enriquecimento do gás de alto-forno na CTE#2.

Aug 17, 2017

By F. K. McIntosh, A. F. Robertson, T. J. Ballard

"INTRODUCTION Molybdenum deposits occur in Halifax County, N. C., near the eastern border of the Piedmont province. The deposits are associated with a small granite body about 2 miles long and half a mile wide. Molybdenite is the principal ore mineral and is found as disseminations or thin stringers in quartz veins and occasionally in the enclosing granite or schist wall rock.The deposits were investigated by Almon F. Robertson and Charles J. Cohen, engineers of the Bureau of Mines, in 1942 and 1943, who recommended that the deposits be explored to supplement reserves of critical war minerals.The Bureau made the initial exploration of the deposits in July 1943 and continued its work to January 1944. Drilling was resumed from July to December 1946 to test the deposits at &eater depth than had been attempted during the previous exploration."

Dec 1, 1947

By Frank Rieber

EVERYONE is familiar with the story of the poor Indian and his leaking tepee. He couldn't repair the leak while it was raining, naturally. And when it wasn't raining, where was the incentive? Even if this traditional Indian was apochryphal, his counterparts are certainly alive today, and operating on a world-wide scale. - A recent issue of the Wall Street Journal, for example, carried an impassioned letter from an old cocoa planter, who wants the world to know why the price of cocoa has gone skyrocketing. For years, he says, British and American interests have bought cocoa at the cheapest possible price and, incidentally, from growers willing to sell at that price. Between them, they didn't put enough money back into the business, either to fight disease in the cocoa groves or to plant new cocoa trees. Until new trees are planted and come into bearing, we will be paying exorbitant prices for our cocoa, and getting less of it.

Jan 1, 1948

By Andrew W. Jenike

The first significant studies of problems related to the handling and storage of bulk solids were reported at the end of the nineteenth century. Early work originated from the necessity to store large quantities of grain and was concerned mainly with pressures affecting the structural design of silos and bins. The Janssen formula (about 1898) and the work of Ketchum [1] form the highlights of that period. In more recent years, progress in mechanization, increasing plant capacities, and rising costs of labor have focused the attention of engineers on the problem of gravity flow of bulk solids. A great deal of work has been done with models, and flow patterns obtained in small scale bins have been described in several publications, for example [2, 3]. An attempt to develop a theory of flow of bulk solids was reported in 1954 [4, 5, 61 and presented to the in a paper [7] in the same year. AIME recommended the continuation of this work and, as a result, Engineering Foundation granted a sum of money to set up a Bulk Solids Flow Laboratory. Two and a half years ago the project gained the support of the University of Utah and a laboratory was set up on the campus of the University. This project is now in progress, it has received the support of the American Iron and Steel Institute and of Kaiser Engineers, Division of Henry J. Kaiser Company. The results obtained to date are summarized in this report.

Jan 1, 1959

By W. J. Wolfe

"Quartz Hill is a large, low- to moderate-grade quartz vein stockwork porphyry molybdenum deposit, discovered in 1974 during a regional stream sediment geochemical reconnaissance survey of southeast Alaska conducted by United States Borax and Chemical Corporation. Mineralization is localized in the upper parts of an Upper Oligocene (30 Ma) composite quartz monzonite stock which is emplaced discordantly into older Cretaceous to Early Tertiary terrain of the Coast Range igneous metamorphic complex of the northwest North American Cordillera. Subsequent fault-controlled, complex multi-stage intrusion, concentrated in the core of the Quartz Hill stock, produced successive pulses of hydrothermal alteration and molybdenum mineralization at about 27 Ma. Overall, the deposit is tabular and flat-lying and well suited to open pit mining. The 0.05% MoS2 grade limit covers an area of approximately 1500 m by 2750 m and extends to a maximum depth of 520 m below surface. Details of grade distribution show two separate lobes of higher grade material within the larger low-grade deposit.A ten year program of exploration drilling, underground development, sampling and metallurgical testwork led to a 1983 feasibility study based on a resource of 1600 million tonnes grading 0.127% MoS2 at a 0.08% MoS2 cutoff The large size of the deposit and its homogeneous grade distribution, typically showing gradual outward decrease of grade, makes in pit grade selection practical at several cutoff levels. Cominco Ltd. now reports a Probable Resource of 210 million tonnes averaging 0.22% MoS2 with a further Possible Resource of 1100 million tonnes averaging 0.12% MoS:z. At low molybdenum metal prices which have persisted for 10 years since the molybdenum price spike of the late 1970s and early 1980s, the Quartz Hill deposit is sub-economic."

Jan 1, 1995

By Andrea Gambi, Giancarlo Olivucci, Maurizio Lenzi

"In the paper a criterion for the evaluation of the sharing of the lateral loads in a piled foundation is presented. It relies on the the compatibility condition between the rotation of the rigid pile cap and the rotations of the pile heads, following in that the criterion suggested by the Eurocode 8 - Part 5. This assumption leads to an analytical solutions which allows to deal with the sharing of the lateral loads and moments by means of two main interaction parameters only. A sharing domain is also derived and it shows the role played by the eccentricity of the lateral load on the values of the axial forces and of the bending moments at the head of the piles.INTRODUCTIONIt is well known that the interaction among soil, piles and foundation is one of the most complex subject to deal with in Geotechnical Engineering. Its rigorous study needs to employ suitable finite element software nowadays available and able to take into account the non linear behavior of the soil as a continuum and the inelastic response of the structure. A deep insight to the topic of the sharing of the loads cannot obviously renounce to this approach.On the other hand it is a daily need of the designers to have at their disposal simple tools that allow to make preliminary evaluations of the basic equilibrium conditions. To this purpose many methods of analysis have been developed in the past to face the sharing of the loads in a simplified version. The present contribution follows this way trying however to introduce some improvements that leads to find a solution that satisfies both the equilibrium of the forces and the compatibility of the movements (Lenzi, Gambi, Olivucci, 2002). The proposed model allows to identify the basic parameters which govern the sharing of the lateral load and it allows to perform also parametric analysis and quick checks that may be useful in the design of the piles."

Jan 1, 2005