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By J. W. van der Merwe, A. Palazzo

"Owing to the corrosiveness of the untreated brackish cooling water typically used for steel mills (and other environments), it is important to treat the water and monitor corrosion in such systems. Generally, corrosion rates are monitored with corrosion probes inserted into a pipeline or vessel. This has been standard practice for many years, and is widely accepted in industry. Typically, two kinds of probes are used - electrical resistance and linear polarization resistance (LPR) probes.In this study, the effectiveness and accuracy of the LPR technique was evaluated by comparing the electrochemical measurements with the results of mass loss tests using corrosion coupons. The corrosivity of the environment, a synthetic brackish water, was varied by varying the calcium hardness and alkalinity, and to simulate actual plant conditions temperatures of 35°C and 45°C were used. In addition to the corrosion rate measurements, the iron concentration was measured, as well as the imbalance from the probe.The corrosion rates obtained by LPR were from 57% lower to 385%higher than those from the immersion tests. Most probe measurements were higher than the immersion results, and 50% of the probe results were50% or more higher than the immersion results. The best correspondence between the two methods was obtained at low calcium levels, except for one measurement that was 93% higher than the coupon results. There was no clear correlation between parameters such as temperature and total alkalinity and the difference between the results. It would therefore appear that LPR measurements can differ significantly from immersion results, and LPR results should therefore be used with caution in industrial applications."

Jan 1, 2015

By P. Chiotti, G. R. Kilp

IN the study of zinc-zirconium1 and zinc-uranium2 systems, vapor-pressure measurements were made in order to establish the equilibrium phase diagrams for a pressure of 1 atm. In each of these systems, only zinc has an appreciable vapor pressure over the temperature range investigated. The zinc pressure was measured over a sufficiently wide temperature and composition range to permit calculation of the standard free energy, enthalpy, and entropy of formation for the compounds ZrZn, ZrZn2, ZrZn3, ZrZn6, ZrZn14 , and U2Zn17. In these calculations the compounds were treated as line compounds. Although the exact composition range was not determined, metallographic and thermal data indicate that the solubility range for these compounds is small. It is to be noted that the compound initially reported to correspond to the formula UZn9, 2 has been shown by the crystal structure work of Makarov and vinogradov3 to correspond to the formula U2Zn17,. The crystal structure is similar to that for the compounds Th2M17, investigated by Florio,4 et al; here M represents iron, cobalt, or nickel. Therefore, thermodynamic calculations are based on the formpla U2Zn17 EXPERIMENTAL The dew-point method employed to measure the vapor pressure of zinc over uranium-zinc alloys has been described previously.2 The same procedure and apparatus were used in measuring the zinc pressure over zinc-zirconium alloys. In the case of alloys in the two-phase region consisting of a zirconium and the compound ZrZn, the Knudsen effusion method was employed to obtain a few values in the temperature range 600" to 560°C. In most cases, tantalum crucibles were used to contain the zirconium alloys. THERMODYNAMIC PROPERTIES OFU2Zn17 A least-squares treatment of the vapor-pressure data obtained for 35 and 65 wt pct U alloys in the temperature range 650° to 940°C gave lOg10PAtm = 7,713/T + 6.33 Here, as in following equations, T represents degrees kelvin and P represents the zinc vapor pressure in atmospheres. The probable errors for the two constants were calculated to be 60.68 and 0.0563, respectively. This relation represents the equilibrium dissociation pressure for the reaction U2Zn17 (s) - 2U(s) + 17Zn(v) The solubility of zinc in solid uranium is negligible and the only additional information required to calculate the free energy of formation of U2Zn17 is the free energy of vaporization of pure zinc. K. K. Kelley5 gives the relations, AF°= 30,902 + 6.03Tlog T + 0.275 X 10-3T2 - 45.03T

Jan 1, 1961

By H. Salamanca

The electric operation and design features of the 11.000 H.P. variable speed SAG mill gearless drive is presented. The function of the frequency converter, control system drive and lubrication systems are described. An analysis of the harmonic characteristic in the Supply System and Motor is presented, and the dynamic development of the stator current, speed and the magnetic flux in the start-up process of the drive is evaluated. Besides, the most important aspects in the commissioning and maintenance of the drive are analyzed.

Jan 1, 1991

By Richard E. Sabaski

The demand placed on the mining industry in the past 15 years for increased production, coupled with lower grade ore and higher cost capital, has resulted in a noticeable increase in grinding mill sizes. The pressure to increase mill size continues. During the mid sixty's and early seventy's, ?larger? conventional ball mills were in the range of 13 - 16-1/2 f t. diameter (4 - 5 m) increasing by the mid 70's to 18 ft. (5.5 m) diameter. At the same time, autogenous mills expanded from 24 - 32 ft. (7.3 - 9.1 m) to the present 34 and 36 ft. (10.b and 11.0 m) diameters. These size pioneers of 16-1/2, 18, and 36 ft. diameter mills from Allis-Chalmers have been free from structural problems, because they were analyzed, modeled, designed, and field tested to meet the challenge.

Jan 1, 1981

By M. S. M. Aljuhani

In this paper, one of the human factors that affect productivity in an underground gold mine in Saudi Arabia was investigated and analysed for the purpose of improving productivity. The human factor that was investigated is labour utilization and labour productivity. In the selected mine, labourer?s performances were measured carefully. It was found that in this mine, workers spend only 65% of the shift time in a productive work, and they spend 35% of the shift time in non-productive activities. As a result, recommendations were presented to enhance productivity in the selected underground gold mine by enhancing labour utilization.

Jan 1, 2002

By Wayne Green

The Regional Municipality of York, located north of the City of Toronto in Ontario, Canada, has experienced unprecedented growth during the past decade, with new home construction averaging 15,000 units per year. This rate of growth is planned to continue well into the future with a projected growth of more than 500,000 new residents by 2031, combined with a tar-get of more than 300,000 new jobs to provide a sustainable economic base for the region. It should be noted that York region has been designated as one of the key growth centers by the province of Ontario, aimed in part to meet the housing and employment needs of Canada?s growing population. York Region is a mix of urban and rural areas and is one of the most desirable areas to live in Southern Ontario. York region offers an attractive lifestyle, with its nine municipalities and the amenities created by the many rivers, streams and protected greenbelt areas that encompass more than 69 per cent of the region?s area.

Jan 1, 2010

By S Kakara, A Kamaraj, S S. Varanasi, B V. R Mandalika, M B. Shaik

The properties of top slags play a very important role in secondary steelmaking. Fluxes should be chosen based on the ladle furnace (LF) slag requirements like viscosity, melting temperature, sulfide capacity, etc. CaF2 and CaO-Al2O3-based synthetic slags are the most used fluxes in secondary steelmaking to improve slag fluidity and interfacial chemical reactions. CaF2 is obsolete due to fluorine pollution and CaO-Al2O3 based slags have 40–50 wt per cent Al2O3 and 30–40 per cent CaO which is not beneficial for desulfurisation. Yet another drawback is that LF slag disintegrates into fine powder during cooling due to phase transformation C2S (2CaO.SiO2). Hence, there is a need for the development of low melting fluxes with high CaO content and the capability to prevent slag disintegration. The current work studied the effect of 0–9 wt per cent B2O3 on physico-chemical properties and characterisation of LF slags. X-ray diffraction (XRD) analyses were carried out to identify mineralogical phases present in slag and Fourier-transform infrared spectroscopy (FT-IR) analysis was done to understand the changes in bonds of B2O3 added LF slag. The characteristic temperature of slag was determined by a hemispherical method using high-temperature microscopy. Empirical models were used to calculate viscosity, break temperature, and sulfide capacity. FactSage™, ver 8.2 (by GTT-Technologies) simulations were carried out to find the equilibrium phase fractions and percentage of liquid slag at different temperatures. New phases such as Ca11B2Si4O22 and Ca2B3O5 were formed in LF slag with B2O3 addition. Based on the results, 0.5–1.0 wt per cent B2O3 was found to be sufficient to prevent C2S-driven disintegration of LF slag. Also, the melting temperature and viscosity of LF slag were reduced by adding 3–8 wt per cent B2O3 due to the formation of BO3 planar triangular structure and low melting eutectics in slag. Liquid slag started forming at a temperature as low as 800°C when B2O3 is >6 wt per cent. It was found that the sulfide capacity, viscosity, and break temperature of the slag decreased with increasing wt per cent B2O3. Based on the analysis carried out, B2O3 can be a promising fluxing material in secondary steelmaking, for improving the desulfurisation kinetics and valourisation potential of LF slag.

Aug 21, 2024

Minerals are vital to any industrialized civilization. Annually, the United States uses more than 4 billion tons of new mineral materials, or about 40,000 pounds per person-about half being mineral fuels and the other half being metals and nonmetallics. Stable and economic domestic mining, mineral, metal, and mineral reclamation industries are essential to the economy. The value of United States energy and processed materials of mineral origin exceds $200 billion annually. Although a number of minerals are imported, especially some designated as "strategic and critical," most U.S. mineral supplies are derived from the domestic mines and processing facilities that you will be seeing, reading about, and visiting as you use this visitor guide. We hope you enjoy your experiences. This pamphlet, a guide to mining and mineral operations that may be observed or visited and some other points of interest relating to minerals, is intended to aid tourists and students who are interested in mining. Some may wish to study our Nation's romantic past; others may plan to enter the minerals industry as a career; still others may have a primary interest in conservation practices. The pamphlet is also intended to aid State and local officials, Chambers of Commerce, and mining firms in answering some of the many questions of tourists and students.

Jan 1, 1976

By J. L. Holman

The Bureau of Mines, at its Rolla Metallurgy Research Center, has devised methods for separating and reusing the major portion of waste plastics discarded in urban and industrial refuse. Waste plastic concentrates from a local collection drive, recycling center collections, urban refuse pilot plants, and the secondary metals industry were separated into three major thermoplastic families--polyolefins, styrenes, and vinyls--based on differences in density using a Bureau-designed sink-float-elutriation hydraulic separator. Other separation methods and systems such as air classification, jigging, liquid media, screening, and electrostatics were studied. Vinyl plastics contain up to 50 percent HC1. It was found that over 90 percent of the HC1 in vinyls can be recovered as usable hydrochloric acid by pyrolysis at 350° C. The remaining pyrolysis products which had heats of combustion in excess of 12,000 Btu/lb, could become valuable as a future source of energy. A characterization study conducted on eight chopped wire insulation wastes from secondary copper and aluminum processors showed that most wastes contained 2 to 7 percent residual metal and large percentages of vinyl. The residual metal content of some of these wastes was lowered to 0.1 percent and the vinyl portion segregated using various separation techniques. The research also suggests ways in which reclaimed thermoplastics may be fabricated into useful products.

Jan 1, 1974

By Harold L. Riley

This Bureau of Mines paper describes the methods and practices used at the Peck quarry of the Crab Orchard Stone Co., Inc., one of the leading producers of dimension stone in the Crossville, Tenn., area. The product is marketed under the registered trademark "Crab Orchard Stone". Another large producer of stone from the Crossville district sells its product under the registered trademark of "Tenn-Quartz". Both companies, and a number of other companies and individuals who quarry and process dimension stone from the same general geological formation, are members of the Quartzite Producers Association of Tennessee. The salable product is shipped throughout the country for use as architectural building stone. In 1959, 653,008 cubic feet of stone was produced in the Crossville area and was sold for $1,414,405. Terms and descriptions used in this report are those of the quarry and building trades. The offices, pitching sheds, wire saws, railroad siding, and storage areas of the Crab Orchard Stone Co., Inc., are on a side road 0.3 mile north from a point 2.2 miles east of Crossville, Tenn., on U.S. Highway 70. The quarry is on this same side road 2.0 miles south of Highway 70. Crossville is 62 miles west of Knoxville and 65 miles northeast of Chattanooga, Tenn.

Jan 1, 1962

By Roy H. Borde

The design of foundations to support overhead signs is primarily based on providing adequate resistance against horizontal wind loads. The typically used subgrade reaction model for the load-deflection analysis of laterally loaded piles and shafts has been found to underpredict the capacity of shafts with length to diameter ratios less than five. The general applicability of an improved model incorporating the influence of shear and moment resistance at the shaft base is demonstrated. The detrimental effect of ground surface slope angle on the ultimate capacity is discussed, and a design chart for estimating the magnitude of the reduction in capacity is presented. A comparison between the predicted and measured responses of nine full-scale load tests performed within this study and sixteen external tests is presented. The models described are implemented in the computer program "LTBASE".

Jan 1, 1988

By Wm. F. Netzeband

"The mode of ore occurrence and the methods and costs of mining at one of the zinc-lead mines in the Tri-State zinc and lead district, Oklahoma, are presented in this paper for the information of mine operators in other districts.No. 2 mine property was acquired by lease in 1918 after some 30 holes had been drilled and a shaft had been sunk to the 305-foot level by the first lessees. After acquisition of the lease, the present operating company drilled a rich ore body on the 260-foot level and in 1920 started sinking two shafts. Production was begun late in 1921, and the mine has been operated more or less continuously to the present time.The mill has a capacity of 400 tons in 10 hours, the usual length of the mill shift in the district.The geology of Mine No. 2 is very similar to that of Mine No. 13 except that the Cherokee shale is thicker, ranging from 80 to 160 feet, and all the formations are correspondingly deeper, the Short Creek oolite horizon here being at a depth of about 300 feet. The oolite has not been found on this property, but the lime comes in at about the level at which the oolite should appear.The ore deposits of Mine No. 2 occur in the brecciated and bowlder ground above the Short Creek oolite. The main or 260-foot level is about 40 feet above the oolite horizon, and the lower or 300-foot level is immediately above it.The ore deposition is controlled by a zone of shearing and fracturing, and the mineable areas are divided into two distinct runs which have a northwest trend with a lean or practically barren area dividing them. This characteristic has controlled the mining to a large extent, for it enables the mine superintendent to locate the large pillars in lean ore and leave only small pillars in the richer ore. Figure 1 shows the outlines of the ore body and the pillars.The ore on the main level occurs disseminated throughout the jasperoid breccia as patches or lenses in the jasperoid, or cementing massive bowlders of jasperoid breccia and chert. The ore of the lower level is more of the bowlder type than that on the main level and occurs chiefly cementing the bowlders but also with some disseminated ore in the jasperoid breccia.The gangue minerals are jasperoid breccia, chert, and dolomite. Calcite is found in minor quantities. Sphalerite is the principal ore mineral; galena is found only in minor quantities around the edges of the ore body. When galena is encountered in this ore body, the limit of the ore can be expected.The exploration and estimation of ore reserves at Mine No. 2 are similar in many respects to the methods used at Mine No. 1.4After the mine was opened up and the general character of the ore deposit had been determined, drilling operations were concentrated along the trend of the shear zone. Later drilling has proved what appears to be a parallel shear zone or an offset of the zone now being mined."

May 1, 1929

By Kevin Beirne

Most people involved in the mining industry are familiar with student-industry co-op work-study programs. Many colleges and universities have used them for years. Northern College’s Haileybury School of Mines student co-op program adds a new dimension of productivity to the college and the mining industry. The college is located in Hailey-bury, Ontario, Canada. An example of the program’s success is the school’s relationship with Sabin Metal’s SMC (Canada) Ltd.’s McAlpine Mill in Cobalt, Ontario. Students gain practical knowledge and experience while industry gains an eager-to-learn worker. And many of the college’s advanced research services are made available to industry to supplement their own capabilities. The McAlpine Mill was established to provide custom milling of slags and ores. It also recovers metal values from other products of the primary and secondary precious metal industries.

Jan 1, 1999

By J. R. Menasce

Mechanization in low-stope panels situated in hard rock infers roof support by tensile bolting to allow free passage of trackless mining equipment in the production areas. This is in sharp contrast to conventional mining, where compressive roof supports?such as timber and grout packs?have traditionally been used, up to 1.5 metres from the production face. Bolting is a hazardous operation because material is dislodged from the roof during the drilling activity. Even with temporary roof support installed, small pieces of rock are dislodged by the percussive action of the drifter. Operations with the man situated directly under the drill, during the drilling activity, are hazardous. The only way to remove the hazard is to move the man away from the machine for as much as possible throughout the complete cycle Costs associated with safety cannot be quantified, but need to form part of the decision-making process. Machine selections based on purchase and running costs alone do not justify the investment cost of mechanized bolters. The equipment selection process needs to take into account the total cost of mining as well as the human safety impact and loss of production costs from having to re-bolt roofs in a production panel to prevent falls of ground. Labour costs in mechanized low-stope bolting are between one-quarter and half the labour costs of non-mechanized bolting. This paper reviews the mechanized bolting option versus handheld bolting from a mining process and cost perspective in a hard rock, low-stope room-and-pillar mining operation in the platinum and chrome industries.

Jan 1, 2006

By J. W. Jensen

EXTENSIVE research and development was performed on the manganese-copper vibration-damping alloys to determine the relationship between the properties of the alloys and variations in composition, fabrication, Mid heat treatment. Mn-Cu alloys with unusually high specific damping capacity, 20 to 25 percent at a stress of 5,000 psi, have also the following useful properties: Tensile strength, 90,000 to 110,000 psi; yield strong, 60,000 to psi; elongation, 20 to 25 percent; hardness, 90 Rockwell B; and fatigue limit at, 28,000 to 30,000 psi. Both standard and special methods of testing were employed to obtain data on strength, modulus, hardness, resistivity, dilatation, micro-structure, crystal lattice, and damping capacity. The extensive tabular and graphical data on these properties are presented for alloys containing 50 to 85 percent as quenched d solution) and after various aging treatments. Expansion coefficients for all Mn-Cu solid solutions are graphed and a dilatometer study of contraction during aging is reported. Although high damping capacity is associated with aging to precipitate a-Mn from solid solution, with a cubic-tetragonal transformation and with the occurrence of antiferromagnetic ordering in Mn-Cu alloys, a tenable theory of the damping mechanism has not been reached.

Jan 1, 1965

By Thomas M. Barczak

The initial Support Technology Optimization Program (STOP),Version 1.0, was released at the 19th Ground Control Conference. This original program has since been updated to Version 2.3 which was released in May, 2001. This paper describes the additional features of Version 2.3, focusing primarily on the following three aspects: (1) including uncontrolled convergence into the design requirements for standing roof supports, (2) the addition of design procedures for cable bolts as an alternative secondary roof support, and (3) the addition of new standing roof support technologies. Another new feature which should facilitate the development of design criteria for standing roof support is the capability to define ground reaction curves through convergence measurements alone without having to make support loading measurements. There are several other new features provided in Version 2.3 which are only briefly addressed in the paper. These include: (1) additional graphics capabilities to facilitate rapid assessment of support comparisons, (2)an East-West designation for support selection to more accurately provide cost and support availability data, (3) additional safety measures including a safety factor to identify support design near the peak support capacity, checks to see if the support dimensions comply with aspect ratio requirements, and a measure of roof coverage for the design layout of the support system. These new features of STOP provide more capabilities to design and analyze secondary roof support systems for conditions which could not be fully analyzed in the original version of the program.

By C. L. Monroe

It has been the custom in recent years to look upon Atlin as a worked-out placer camp. This is a conception, however, which is far from the real situation. The placer-gold deposits of Atlin are today, after thirty-one years of continuous working, a field well worth the attention of the mining world. It is true that the shallow diggings (the 'easy money') have been practically cleaned out, but although there have been perhaps ten millions, or more, in gold already taken from the district, there are still many more millions left in the creek beds . A conservative estimate of the gold still remaining in one creek alone, Spruce creek, for a long time known as the 'prospector's meal ticket', would place the amount at anywhere from fifteen to twenty million .dollars, and there are a number of other creeks that have never been thoroughly worked, and some only partially prospected. That the true situation is beginning to be recognized by those who are on the lookout for a profitable field for investment, is born out by the fact that, within the last few years, New York capital directed by Mr. Charles V. Bob, who is also responsible for the opening up of the Engineer mine, has installed on Pine creek, where the first discovery of gold in the district was made, one of the largest hydraulic mining plants on the continent, utilizing six miles of the old hydraulic ditch of the Discovery Mining and Power Company, and over two miles of pipe line. On Boulder creek, where already two millions have been taken out, the Consolidated Mining and Smelting Company are on their third year of development work in opening up the unworked ground, while on Otter creek a newly organized French company have started a plan of development which will involve an expenditure in the neighbourhood of $200,000, and two or three years' work, before they can hope to find gold in paying quantities. It is probably safe to prophesy that placer gold will be produced in the Atlin district for the next fifty years

Jan 1, 1929

By R. Musu, J. A. E. Bell

P.T. Inco has constructed a smelter to produce 45 000 tonnes (49 500 tons) of nickel per year as a nickel matte from the lateritic ores of Sulawesi, Indonesia. The facilities include mines, five screening stations, two dryers, three novel reduction kilns, three electric furnaces, three top blown rotary converters, and associated infrastructure of port, towns and a hydroelectric generating station. The screening stations and converters are unique in the industry. The problems encountered in the construction and operation of this complex facility in remote Indonesia are described.

Jan 1, 1979

By Özgen C. Karacan

It is generally accepted that typical coalbed gases (methane and carbon dioxide) are sorbed (both adsorbed and absorbed) in the coal matrix causing it to swell and resulting in local stress and strain variations in a coalbed confined under overburden pressure. The swelling, interactions of gases within the coal matrix and the resultant changes in the permeability, sorption, gas flow mechanics in the reservoir, and stress state of the coal can impact a number of reservoir-related factors. These include effective production of coalbed methane, degasification of future mining areas by drilling horizontal and vertical degasification wells, injection of CO2 as an enhanced coalbed methane recovery technique, and concurrent CO2 sequestration. Such information can also provide an understanding of the mechanisms behind gas outbursts in underground coal mines. The spatiotemporal volumetric strains in a consolidated Pittsburgh seam coal sample were evaluated while both confining pressure and carbon dioxide (C02) pore pressure were increased to keep a constant positive effective stress on the sample. The changes intemal to the sample were evaluated by maps of density and atomic number determined by dual-energy X-ray computed tomography (X-ray CT). Early-time images, as soon as CO2 was introduced, were also used to calculate the macro porosity in the coal sample. Scanning electron microscopy (SEM) and photographic images of the polished section of the coal sample at X-ray CT image location were used to identify the microlitho types and microstructures. The CO2 sorption-associated swelling and volumetric strains in consolidated coal under constant effective stress are heterogeneous processes depending on the litho types present. In the time scale of the experiment, vitrite showed the highest degree of swelling due to dissolution of CO2, while the clay (kaolinite) and inertite region was compressed in response. The volumetric strains associated with swelling and compression were between ± 15% depending on the location. Although the effective stress on the sample was constant, it varied within the sample as a result of the intemal stresses created by gas sorption-related structural changes. SEM images and porosity calculations revealed that the kaolinite and inertite bearing layer was highly porous, which enabled the fastest CO2 uptake and the highest degree of compression. Keywords: Coal; Carbon dioxide; Sorption; Swelling; Sequestration; X-ray computed tomography; Volumetric strain; Gas outbursts

By B. P. Faulkner, M. Weinecke

Svedala started a development program in 1997 to develop a process to convert waste tires into valuable commodities. A review of numerous approaches revealed short-comings in the various approaches either process, mechanical, combination of factors, or trying to emphasis the production of low value products. A market study revealed that a process that could produce a good grade of carbon black would be economically feasible. This paper discusses the laboratory and pilot plant development and commercial plant design.

Jan 1, 2001