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By G. L. Oldright

In the first Report of Investigations of the present series?(No. 4562) the usual course of progress ill reducing the minerals of low-grade ores to their valuable metallic components had been noted as advancing along two lines to concentrate a usually diminishing percentage of these minerals to a smaller bulk of richer product, and then to smelt the smaller bulk more cheaply per pound of metal produced. Fundamental properties of lead compounds made it difficult to treat much richer lead products than are treated at present in several steps of conventional lead smelting, unless ?marked modifications were made. No limits to the richness of the feed itself' were set by the ore (Scotch) hearth; on the contrary, the richer the feed, the better the results given by the hearth. The natural field of operation of the hearth, as determined by the ores available, was seen to lie in the Central United States, with their lead concentrates containing negligible quantities of precious metals and. with few ores of such metals available for use as fluxes. It was noted) however, that even in its chosen field, the Scotch hearth, or "ore" hearths developed from them, was not always used; the usual smelting practice was followed, at times, of sintering followed by blast-furnace smelting for even rich ores.

Jan 1, 1949

By W. W. Fowler

ORIGINALLY designed for copper smelting only, the reduction works of the Cerro de Pasco Copper Corp. have been expanded over the years until now twelve different metals are produced, together with some seven other items which are used locally. Although the total tonnage treated is comparatively modest, as smelting plants go, the variety of operations makes one of the most complex and interesting metallurgical problems in the world. The original plant, at La Fundicion, operated from July 1906 until September 1923. In 1922 a new copper smelter was built at La Oroya, which produced its first copper on Nov. 23, 1922. It is in this plant, greatly enlarged, that metallurgical operations now center. La Oroya is situated at the junction of the Cerro de Pasco Railroad and the Ferrocarril Central del Peru, at an altitude of 12,175 ft.-well over two miles. Many of the various operations stem from two principal smelting circuits which are themselves of conventional types. Copper ores and concentrates are roasted, smelted in reverberatory furnaces and converters, and blister copper produced. Lead ores, concentrates, and other materials are sintered, smelted in blast furnaces to crude lead which is partially fire-refined, and finally electrolytically refined by a modified Betts process.

Jan 1, 1945

On November 9, the Reynolds Metals Company cut production by 12 at its primary aluminum smelters at Troutdale, Oreg., and Longview, Wash., as a result of an earlier 25% power cutback by the Bonneville Power Administration due to lower than normal stream flow in September, the Aluminum Company of America had closed one potline at its Vancouver smelter because of the power cutback. Nearly 700 union workers at Anaconda Aluminum Company's primary aluminum smelter at Sebree, Ky., walked off the job when their contract expired or, November 15, after rejecting a proposed 3-year contract. The smelter has an annual capacity of 180,000 tons mid accounts for 50% of Anaconda's aluminum production. No talks are scheduled.

Jan 1, 1979

By H. Krogerus, P. Niemelä, P. Oikarinen

High carbon ferrochromium is produced by carbon reduction. No replacement for carbon as reductant has yet been developed. The reduction creates a considerable amount of CO-gas. In open and semi-closed furnaces the gas is burned when leaving the burden. In closed furnaces the formed gas is sucked out by a fan, washed and utilised as fuel. The formation of carbon monoxide is presented briefly starting from thermodynamic considerations up to solid and liquid state reduction. The volume, composition and energy content of the furnace gas are discussed, focusing on the raw materials and pre-treatment processes of the furnace feed as well as on the process equipment and control. Outokumpu has been using closed and sealed furnaces and utilising the CO-gas in its Tornio Ferrochrome Works since 1968. Today in Tornio with an annual ferrochromium production of 260 000 t CO-gas production is 186 million m3, representing 68 MWh an hour. At the same time the furnace power input is 95MW. About 98 % of the CO-gas is utilised, whereof 30% in the ferrochrome production itself. This paper focuses on the characteristics and utilisation of CO-gas. CO-gas is secondary energy, which on one hand saves primary electric and fossil fuel energy in ferrochromium production and, on the other, replaces other fossil fuels at the adjacent steel works. The characteristics of the fuel, requirements for utilisation as well as health and safety aspects are discussed. Utilisation of the gas has a high impact on the total dust and gaseous emissions and on the energy optimisation at the ferrochromium and steel works.

Jan 1, 2004

By Michael Wieland

The resolving capacity of the thermodynamic work-principal model has been seriously refined over its twelve year history, so a review of the innovations, wrong turns and their rectification is warranted to help future researchers. The work-principal model rests upon the four laws of thermodynamics that drive the universe and relatively few other assumptions: like the removing and imposing of constraints on the quasi-potential to yield trapped minimum key-states that represent the wanted process. The formative research was concerned with the role of ingredient changes, the removal of booster influence and the quench temperature with which to reckon toxic fumes. The transfer of reaction-zone energy as work upon the surrounding rock/water/fixture was not fully rationalized until the notion of reversed-inertial pressure was formulated and determined (for water) with underwater trinitrotoluene (TNT) shots. The rock-water-jelly model incorporated that term into its dynamic pressure formula as a way to represent rock blasts or underwater shots, while the zone of reaction gases remained trapped. The real irreversible thermodynamic process, which yielded the total expansion work, was later complemented with a wholly reversible imaginary process, to form a closed thermodynamic loop, with a remarkable consequence – the determination of the theoretical heave and hence, the undissipated-shock by difference from the total work. With the wholly developed model, it was recently possible to quantify the time retardation of reaction chemistry for non-molecular (mining) explosives, as compared to the rather negligible time-retardation found for the molecular (military) explosives in underwater tests.

Jan 1, 2009

As part of a comprehensive risk analysis which was carried out into the effectiveness of the water barrier between South Deep and Randfontein Estate mines, the potential threat posed by large seismic events was assessed. The study covered several aspects. Firstly, an estimate of the maximum credible earthquake was obtained from a probabilistic analysis of the regional seismicity of the previous 25 years. Allowance was made for ?reservoir-induced? effects by increasing the estimate of the size of the maximum credible earthquake from ML= 5.1 to ML= 5.5. Based on available knowledge of the geological structure, the possibility of such an event occurring in the vicinity of the barrier pillar was estimated. The possibility of substantial damage to the barrier rock mass, resulting as a consequence of a large event, was assessed. The likely damage to the concrete control plugs installed in five tunnels that penetrated the barrier, which might result from a ?near-miss? by the largest possible seismic event or from a ?direct hit? by a smaller event, was also considered. It was concluded that there was a negligibly small possibility that the maximum credible earthquake could occur close enough to the barrier, and in such a manner, as to cause any damage to it or to the plugs in the tunnels passing through it. The possibility of serious plug damage occurring as a result of a ?direct hit? by as maller event was slightly greater, but still sufficiently remote as to be of no practical concern at all.

Jan 1, 2006

By E. O. RHODES

Germany's' wartime coal-tar industry had two main branches, which can best be considered individually because their raw materials, operations, and distributions were almost completely separated. One branch, old and well-established, was concerned almost entirely with processing coal tar produced by the high-temperature carbonization of caking bituminous coal. Carbonization was effected principally in byproduct- coke ovens and to less extent in vertical, horizontal, and inclined retorts. The high-temperature tar was all processed in tar-distilling plants that handled high-temperature tar almost exclusively.

Sep 1, 1947

By L. Clark

Despite near-record commodity prices, the mining industry continues to search for ways to maintain profits in these times of steadily increasing energy prices and steadily decreasing grades. The pressure is still on today’s miners to continuously improve their operations because they know that one day prices too will drop. Some, however, have seized the opportunity to employ systematic methods to reduce costs and increase the efficiency of their workforce and equipment. As a result, closer attention is being paid to scheduling and the value that could be added by defining the extraction sequence that maximizes the net present value [NPV] of a project. This paper will discuss the challenges faced by Newmont Mining Corporation [Newmont] at its operations and the application of sophisticated software tools and methods in its search of solutions to this problem.

Jan 1, 2007

By William R. Yernberg

The 26th Peruvian Mining Convention (Convención de Ingeneieros de Minas del Perú) was held Sept. 15 through 19, 2003, in Arequipa. The convention was sponsored by the Peruvian Institute of Mining Engineers (Instituto de Ingeneiros de Minas del Peru). The Institute has been organizing these events since 1954. They are now held every other year. The conventions spotlight Peru’s mineral resources and have contributed to the tremendous growth of the Peruvian mining industry. This year’s meeting consisted of technical sessions, forums, field trips and social activities. It was held at the Tecsup Institute of Technology of Arequipa. More than 3,000 mining professionals attended. As always, the meeting was well organized, and participants expressed gratitude to the organizing committee for another successful meeting.

Jan 1, 2004

By Mike Muchard

STATNAMIC load testing augmented with embedded instrumentation has been successfully used to obtain structural and geotechnical design information on large diameter spun cast concrete cylinder piles on many large marine construction projects. The paper focuses on one particularly interesting large marine project involving a new bridge to St. George Island, Florida where instrumentation and STATNAMIC load testing was used in conjunction with static load testing on high capacity piles. The information presented includes embedded instrumentation measurements taken during pile fabrication (post-tensioning), during pile driving, during static load testing, and STATNAMIC load testing. As much of this data is the first of its kind on concrete cylinder piles, it is exciting to present the foundation industry with this additional insight as to the behavior of this pile type and the accuracy of the methods used to test them.

Jan 1, 2005

By Joe Maher

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Jan 1, 1976

By Peter Klaver

Deep tunnels have been used for decades for the temporary storage of large volumes of urban runoff, both storm water and combined sewer overflow (CSO). Tunnels are attractive because they reduce surface disruption and do double duty as storage and conveyance systems, collecting overflows from multiple locations and transporting them for treatment to various facilities. Like any hydraulic system, however, there are dynamic effects that must be fully understood during the design phase so that the final constructed product does not have unintended negative consequences. Preliminary sizing of storage tunnels is typically based on the total volume required. For example, if studies have determined that a volume of 56.8 ML (15 million gal) will provide the intended level of control, then that figure can be used, along with a preliminary idea of the desired tunnel length, to compute the required diameter. Of course, filling a long tube with water from various points along the way is not at all the same as pouring water into a bucket, and these dynamic effects require additional attention from design engineers. The rapid filling of storage tunnels can lead to the formation of bores, which are essentially moving walls of water. An open channel bore can build in height until it reaches the crown of the tunnel, at which point it becomes a pipe-filling bore. Figure 1 depicts both kinds of bores moving upwards in a rapidly filling tunnel. Bores can strike the ends of tun-nels with tremendous force, driving water and entrained air upwards into dropshafts and creating strong pressure surges in portions of the tunnel that are already filled. If the hydraulic surges are high enough to reach grade, they can cause overflows and/or damage structures at the surface. Trapped air pockets can occur through several phenomena, including the reflection of bores off dropshaft structures and the occurrence of ?premature pressurization.? The latter refers to the situation where the inflow to a tunnel is increasing more rapidly than the tunnel can convey it, such that the pipe becomes surcharged at an upstream point while points downstream are still flowing as an open channel. These air pockets are a great nuisance as they migrate toward points in the tunnel where they can rise to the surface, which are often shafts that are already filled with water (Fig. 2). The ?geyersing? that results can be hazardous and costly.

Jan 3, 2010

By M. Stephton, L. A. Cornish, R. Süss, N. B. Maledi, J. H. Potgieter, L. Chown

In today?s gas turbines, the emphasis is on saving energy and reducing the amounts of pollutants emitted. This can be attained only by designing alloys with higher melting points and the capability to retain mechanical integrity at increased temperatures. The development of nickel-based superalloys (NBSAs) has reached its limit, as the alloys are operating at critical temperatures close to their melting points. Further increase in the operating temperatures will result in dissolution of the strengthening phases and even melting. Recent trends are towards developing materials that are adequately strong but have much higher melting points and corrosion resistance than the NBSAs that are currently in use. Studies conducted on Pt alloys with similar structure to the NBSAs have presented mechanical results that are promising. This has led to further development of these alloys as a replacement for NBSAs. The operations of gas turbines are usually limited by hot corrosion, which could lead to catastrophic failures. Increased temperatures have an adverse effect on the corrosion of the alloys by making the environment more aggressive. Hence, during a material selection process, the corrosion behaviour of any selected material for a highly specialized application such as gas turbines needs to be assessed. Generally, coatings are applied to combat degradation by salt deposits, hence coated and uncoated NBSAs were selected as benchmark alloys. Corrosion mechanisms and kinetic studies of the Pt alloys were conducted. High temperature hot corrosion (HTHC) tests were conducted at 950°C for540 hours. Analysis of the corrosion products was conducted using a Raman spectrometer, scanning electron microscope with energy dispersive X-ray spectroscopy (EDS) optical microscopy, and X-ray diffraction study of the phases that formed. Both coated and uncoated NBSAs failed under the test conditions. Samples were covered with a porous non-adherent greenish layer which is characteristic of NiO. Pt alloys displayed superior corrosion properties compared with the benchmark alloys.

Jan 1, 2006

By J. D. Miller, C. L. Lin

As the techniques and resolution for 3-D spatial analysis have advanced in the last decade, it is now possible to map in detail the microstructure of multiphase materials in three-dimensional digital space. In this regard, three-dimensional x-ray microtomography offers a unique imaging capability. Spatial resolution on the order of ten microns can be achieved with the use of microfocus x-ray generators. Recently, a state-of-the-art cone beam x-ray microtomography system has been installed at the University of Utah for the quantitative analysis of multiphase materials in three dimensions. This facility has been designed to obtain 2048 x 2048 pixel reconstruction over a 10-mm diameter, while also allowing for the imaging of somewhat larger (40-mm) objects. The system is capable of handling high-density materials, even materials having a density as high as 8.0 g/cm3. This unique, one-of-a-kind, instrument will be used to obtain three-dimensional spatial reconstruction for such applications as specific examples 3D liberation analysis, pore structure analysis of particle beds during filtration and air-void system of concrete structures. The utilization of x-ray microtomography not only will allow for quantitative analysis of multiphase systems but also allow for textural characterization and the determination of phase continuity. In this paper, we present information regarding the current use of this new facility and reviewed potential applications for the advanced analytical system.

Jan 1, 2001

By R. A. Williams

Electrical impedance tomographic methods have been applied to a variety of mineral and chemical processes in the laboratory and on plant. This review paper surveys technical developments in measurement methods to enable quantitative extraction of key process information in the form of mapping of concentration profiles, mixture homogeneity and suspension velocity. The methods for determining velocity are summarized, since this is of especial interest when applied to opaque systems where most conventional optically based measurements fail. A recent significant development is the use of ultra-high speed measurement that now allows velocity vectors to be extracted for fast moving mixtures and fluids (up to several metres per second). New data are reported pertinent to low and high solids concentration flow in pipelines. Use of the methods offer improvements to design of such systems but also points to the use of tomographic electrical sensor as online flow measurement and fault detection. This offers new opportunities for applications and benefits in the design and monitoring of mineral slurries and sludges.

Jan 1, 2008

By E. F. Divers

This Bureau of Mines report describes the results of a program to develop small, rugged mechanical dust collectors (scrubbers) with high dust collection efficiency and low energy comsumption for controlling dust in coal mining operations. All of the scrubbers described are similar in configuration and are powered by 6-hp, 2,000-ft3/min vane axial fans. Air pressure differential is less than 6 inches water column. Height of the scrubbers? including fan is less than 14 inches, width is less than 16 inches, and length is less than 45 inches. The flooded fibrous-bed scrubber achieved respirable (less than approximatey 7 µm) dust collection efficiencies of 95 percent. The small-diameter-cyclone scrubbers showed about 92 percent efficiency and can be best where excess water is a problem. The wetted brush scrubber showed 88 percent efficiency at low cost, and the wetted fan scrubber showed a slightly lower efficiency (87 percent) but offered the smallest size and cost. A suitable water droplet eliminator is described.

Jan 1, 1978

By R. A. Friedel

THE IMPORTANCE of infrared and ultraviolet-visible spectrometry in studies of the structure of coal and similar substances is described. Special experimental techniques have been developed for these studies. Thin sections of coal are preferred, but halide pellets are easier to prepare. Information obtained from infrared spectra on chemical functional groups has been discussed; the importance of both intensities and wavelengths of absorption bands has been emphasized. Functional groups assigned include aliphatic and aromatic CH, methylene and methyl groups, hydrogen-bonded hydroxyls, hydrogen-bonded and chelated carbonyls, phenolic structures, minerals, and aromatic structures that are benzenoid or polynuclear. Infrared studies of structures of coal extracts, distillates, and reaction products of various processes, both chemical and physical, are discussed. Coallike infrared spectra of chars of model compounds have been utilized extensively in studies of coal structure. Ultraviolet-visible absorption spectra of coals show a lack of fine structure and low spectral intensities. These results have been applied to the questions of the chemical and physical structure of coal, particularly the question of polynuclear aromaticity of coals. The color of coal is also treated. The physical-chemical origin of the color of coal may be due to free radicals, as interesting correlations of ultraviolet-visible spectra with electron paramagnetic resonance have been obtained. The optical color of coal has been explained and simulation of the color changes observed in thin sections has been carried out, The spectra and structure of coal derivatives and other carbonaceous materials are also discussed. Possible sources of error in absorption spectral measurements are pointed out. Limited measurements of the ultraviolet-visible reflectance spectra of coal are described.

Jan 1, 1967

To provide a flexible, low-maintenance, low-cost continuous mine air monitoring system as an alternative to conventional fixed-point, electronic monitoring systems. Background Continuous monitoring of mine air is highly desirable (and often required) not only to improve miner safety, but also to increase mine productivity. Continuous air monitoring systems can provide earl" warning of developing fires, excessive methane accumulation, reduced oxygen levels, and other developing problems in remote, inaccessible or sealed areas, and in active workings. Fixed-point, electronic systems require one Sensor for every gas to be measured at every defined monitoring location. As the number of monitoring locations increases, so does the cost, along with increases in the time required for routine maintenance and calibration of the sensor System cost also increases when monitoring locations are identified for mine areas requiring permissible electrical equipment.

Jan 1, 1988

By Hiroshi Soda, Atsumi Ohno, Hiroyuki Yamazaki, Alexander McLean

INTRODUCTION The method of heat removal during a casting process strongly influences the crystal morphology of the cast product and hence the metallurgical and mechanical properties of the solidified materials. In this paper, the Ohno Continuous Casting Process (OCC) is described in terms of the casting conditions and the type of structure observed in the cast product. Significant improvements are observed in workability, fatigue strength and corrosion resistance of castings produced by the OCC method, Ohno (1988). Applications of this technique to low melting point nonferrous metals and alloys are discussed. The feasibility of the application of this technology to high melting point materials is outlined. THE OCC PROCESS The OCC process involves delivering liquid metal into a heated mold, the temperature of which is held just above the solidification temperature of the metal to be cast. This is the key point which differentiates the OCC process from the conventional continuous casting method. A schematic illustration of the OCC process is shown in Figure 1. The Formation of a Single Crystal When the mold is heated above the solidification temperature of the metal to be cast, nucleation on the mold surface is prevented and solidification takes place only at the mold exit. The heat is extracted through the product being cast by a cooling device located near the mold outlet. Crystals are formed only at the tip of the dummy bar at the start of casting, and as the dummy bar travels away with a progressively increasing speed from the mold, the position of the solid liquid interface will align with the mold exit, producing a unidirectionally

Jan 1, 1990

By Warren M. Mahan

A rotary kiln process was developed by the Federal Bureau of Mines to produce consistently an iron product containing 3 to 7 percent nickel. Cuban laterite and serpentine ores were smelted in a gas-fired batch-rotary kiln) 5 feet in diameter and 9 feet long. The metal contained 2 to 4 percent carbon, with little or no silicon, and could be produced on a large scale with modest capital investment. A total of 121 tests was run using this procedure. The tests were conducted with a maximum temperature of 2,625° F., using linings of firebrick containing 40 to 70 percent alumina. Slags in the kiln were acid to neutral. The material in each batch passed through three stages: (1) Sponge metal, (2) carburization, and (3) balling and meltdown. Half the tests were made while firing the kiln with atmospheric-temperature air; the remainder were fired with preheated air. Tests showed that preheated air decreased fuel requirements, dust losses, and reducing agent, and increased the capacity of the kiln.

Jan 1, 1960