Search Documents

By Cleveland Meeting

Jan 1, 1945

Jan 1, 1892

By Y. Nahmad- Molinari

We present a novel on line inductive sensor for the determination of the quality of the concentrates of iron ores. This device is coupled with a cheap USB Data Acquisition System that makes it versatile enough to simultaneously control up to seven fluxes at a very low cost (< $300 US dollars), and achieves a resolution better than 0.5 % on the determination of the magnetic iron content in the concentrate. A RLC circuit with its inductive element placed surrounding a sample of pure magnetite concentrate is tuned at its resonance frequency, by means of adjusting, the feeding voltage of a voltage-controlled oscillator (VCO) and several samples with mixtures of different contents of silica and magnetite are placed in order to get a calibration curve. After some signal conditioning, a National Instruments USB-DAQ NI-6008, acquires the amplitude of the signal via USB port on a PC using a Lab-View program designed for such purpose, in which the calibration curve is used for on-screen data presentation directly in percent of magnetite content. The implementation of this device for control purposes on line directly placed on the concentrators would allow better efficiency of the process and higher quality of the final concentrate by con-trolling; the rotation speed, the rising or dilution water fluxes or bypasses towards milling recirculation cycles.

Jan 1, 2014

By John R. Wynnyckyj

Results of correlations between strength-development and sintering shrinkage occurring during induration are presented. A mathematical treatment of the shrinkage kinetics is, next, given and is based on the use of semi-empirical equations. The discussion stresses the significance of kinetic constants and activation energies in the assessment of iron ore concentrates for pelletizing and induration. Next, starting with the assumption that there is a need for parameters to characterize the iron-ore concentrates and relate these parameters to shrinkage-kinetic constants and balling behaviour, results of compaction measurements and pore structure characterization (mercury porosimetry) are presented and discussed.

Jan 1, 1977

By N. M. Cheimanoff

GEOCAD is an ambitious research program aimed at the development of a computer based system assisting the geologist and the production or planning engineer. BONANZA, its mining part, is a computer production scheduling tool (short to medium term) of particular relevance to complex orebodies. The principle is to simultaneously use a powerful information management system (CAD potentialities) and small expert modules integrating the exploitation context and the engineer&apos;s knowledge (Artificial Intelligence tecniques). As an illustration, a module of mineable block determination for underground exploitation is discussed.

Jan 1, 1989

By R. K. Koch

The normal spectral emissivities of liquid Ti, V, Zr, Mo, and Pt were determined at the fusion temperatures in an electron-beam furnace using a water-cooled copper hearth. The normal spectral emissivities were estimated above the melting points by using adjusted two-color temperatures as approximations of the true temperatures for substitution in Wien&apos;s equation. Simultaneous brightness temperatures were determined with a micro-optical pyrometer. The true temperature ranges covered were 1,668° to 1,885° C for Ti; 1,919° to 2,013° C for V; 1,855° to 2,367° C for Zr; 2,610° to 2,751° C for Mo, and 1,772° to 1,990° C for Pt. The spectral emissivities for titanium and zirconium decreased with increasing temperature. At an effective wavelength (?) of 658 mµ the emissivity of titanium ranged from 0.51 to 0.45 and zirconium, from 0.47 to 0.41. The emissivities of vanadium (? = 658 mµ) and molybdenum (? = 657 mµ) were constant at 0.41±0.02 and 0.33±0.01, respectively. The spectral emissivity of platinum (? = 658 mµ) was constant at 0.39±0.02 up to 1,900° C; above that temperature anomalous data were obtained. A mass spectrometric study indicated that platinum was reacting with back-streaming silicon vapors from the diffusion pump when the ambient pressure was greater than 2 X 10-5 torr.

Jan 1, 1973

By E. C. W. Perryman

The wide grooves formed at the grain boundaries when high purity aluminum is attacked by hydrochloric acid or sodium hydroxide have been attributed by earlier workers to the high energy of the grain boundary material. The effect has been investigated for high-purity AI-Fe alloys with up to 0.055 pct Fe as a function of iron content and heat treatment. It is shown that the explanation given above is untenable, but that the results can be explained on the assumption that iron segregates to the grain boundary in solid solution. IN 1934, Rohrmann¹ showed that aluminum of 99.95 pct purity suffered intercrystalline corrosion when immersed in 10 to 20 pct hydrochloric acid, and that the susceptibility to intercrystalline corrosion depended upon the heat treatment given. The greatest susceptibility was found for specimens quenched from a high temperature (600°C) and the lowest susceptibility for specimens cooled slowly from that temperature. Lacombe and Yannaquis2 have shown that super-pure aluminum (99.9986 pct) annealed at 600°C suffers intercrystalline attack in 10 pct hydrochloric acid and that this attack is intensified by anodic dissolution in the same solution at a current density of 10 milliamperes per sq dm. No difference in extent of intercrystalline attack was found between the 99.993 and 99.986 pct Al, which led the authors to suggest that impurities played only a secondary role in the mechanism of intercrystalline corrosion. It was found, however, that the attack at the grain boundaries depended upon the relative orientation of the grains, large differences in orientation favoring rapid attack. Boundaries where the two neighboring grains were similarly orientated showed high resistance to attack as did boundaries between grains which were in twin relationship. These observations led Lacombe and Yannaquis to suggest that the intercrystalline attack was due to lattice discontinuities present at grain boundaries. Assuming that the grain boundary is a layer three to five atoms thick and has a crystal structure which is a compromise between the two neighboring grains it is clear that the discontinuities will increase with increasing difference in orientation between the neighboring grains and hence the increasing tendency to intercrystalline attack. Roald and Streicher³ investigated the effect of heat treatment of aluminum alloys ranging in purity from 99.2 to 99.998 pct on the corrosion resistance in 20 pct hydrochloric acid and 0.30N sodium hydroxide. They found that in hydrochloric acid the intercrystalline attack appeared to be determined by the type and quantity of impurities present and by the relative orientation of the grains. No difference in the susceptibility to intercrystalline attack was observed between specimens quenched and those furnace cooled, from 575°C. In 0.30N sodium hydroxide some materials exhibited intercrystalline attack, this taking the form of V-notches. Rohrmann¹ offered no explanation for the greater susceptibility to corrosion of material quenched from 600°C. It seems possible that this difference is connected in some way with a different distribution of impurity elements in the quenched and slowly cooled specimens. The fact that Roald and Streicher8 observed no difference between quenched and slowly cooled specimens may possibly be due to differences in either rate of cooling or silicon content or possibly both. Both these would be expected to have an effect on the distribution of impurity elements. Although the rate of cooling used by Rohrmann was slightly more rapid than that used by Roald and Streicher the position cannot be clarified because Rohrmann does not give the silicon content and Roald and Streicher give the silicon contents of only a few of their alloys. That Lacombe and Yannaquis2 found no difference in corrosion behavior attributable to impurities between the two materials they used may be because both were of high purity compared with the aluminum used by Rohrmann.¹ Although they found no difference in the corrosion behavior of their two materials it is possible that the results obtained by Lacombe and Yannaquis may, nevertheless, have been influenced by impurity distribution, since, on the transition lattice theory of grain boundary structure, it would be expected that sparingly soluble impurities would tend to segregate to boundaries where the orientation difference is such that there is a greater density of atomic sites of suitable size to contain them. It was considered worth while, therefore, to examine the corrosion properties of a series of materials of differing impurity content with the objects of confirming the experimental observations made

Jan 1, 1954

By J. Starkey

A comminution circuit in recent history, is one of the most difficult parts of a mineral processing plant to design with confidence. It is usually the most costly part of a plant to build, and it can consume up to half or more of the energy used on a mine site. To suggest that comminution energy usage is sustainable in the long term is not possible at this time. What we have to choose from today, based on more than 50 years of experience, does include the best available technology, and the best way to design it. There is controversy in the industry as to how to properly approach the subject of comminution design, with many of the optional solutions requiring a level of training and expertise beyond the ability of a non-specialist engineer. Semi-autogenous grinding technology in particular, has not been properly appreciated because of many recent mistakes in its application and design, which have blurred the positive perception about what SAG technology is, how it can be used, and how it needs to be designed and built. In order to change this, mine owners and senior managers need to take responsibility for, and learn to understand the fundamental challenges that a comminution circuit poses to the project, to the design process, to the operators who use the equipment, and to the resulting metallurgy. This address is intended to summarize these challenges and offer fundamental engineering solutions, which are clear, specific and in a format which is directly applicable to the mining and mineral engineering community.

Jan 1, 2018

By John D. Godfrey

Geological mapping on the Canadian Shield in northeastern Alberta outlined severalgranitoid rock massespotentially suitable as building stone. A particularly attractive prospect, the Chipewyan Red Granite, was subjected to an aerial survey and ground check. The petrologic and fracture characteristics critical for quarrying and use as a building stone were assessed in the course of detailed mapping at two of the most favourable sites. The extension of good rock was tested to shallow depths at one site by shallow diamond-drill coring. , The Chipewyan Red Granite displays a warm red colour, medium grain size and fairly massive texture, and takes a good polish. Deleterious geologic features studied in outcrop and subjected to structural analysis included regular joint systems, quartz veins, pegmatite dykes, basic shear zones and fault zones. Many of these key geologic features are systematic and hence predictable for stone quarrying purposes; other features, such as irregular fracelM tures, are non-systematic and arefar less predictable. The megascopic structural features studied show similar preferred orientations which appear to be collectively related to the tectonic history.

Jan 1, 1979

By John W. Graydon

Incineration is an attractive alternative to the disposal of MSW in landfill sites. However, the process of incineration generates fly ash which contains significant levels of leachable heavy metals - particularly cadmium, lead, and zinc - and it is essential to manage this fly ash in an environmentally sound manner. The compositions, phases, textures, morphologies and size of fly ash particles have been studied by light microscopy, scanning electron microscopy, X-ray microanalysis, and X-ray diffraction. The detailed spatial relationships and speciation of the environmentally significant constituents have received particular emphasis. The information obtained is useful in understanding how fly ash is formed during incineration, in understanding the leaching behavior of untreated fly ash if it is disposed of in a landfill and, most importantly, in guiding the development of the best treatment strategies for fly asti to mitigate its environmental impact.

Jan 1, 1992

[ ]

Jan 1, 1907

By J. H. Jacobs

In late 1946, research was begun at the Bureau of Mines Electrometallurgical Laboratory at Boulder City, Nev., to determine the possibility of electrowinning manganese from chloride electrolytes on a continuous basis. All phases of electrodeposition were investigated on a small scale it the laboratory, and the results were reported by Jacobs and Churchward. These results indicated that a chloride process had certain possible advantages over the sulfate process that made it worthwhile to continue the investigation on a semi-pilot-plant basis, and this paper reports the results of this work. Research and development work on a process for electrowinning manganese from low-grade ores has been carried on intermittently by the Bureau of Mines since 1936. A process was developed, using sulfate electrolyte, that has been extensively described in the literature.

Jan 1, 1951

By Bruno C. Boik

INTRODUCTION Cost Management is the evaluation and control of project scope, budgets, and costs with the objective to minimize costs and maximize the benefits to be derived from the use of project resources in conformance with Criteria stipulated or approved by the Owner. In order of importance, Cost Management is one of the most prominent Project Management functions because of its impact on the financial success of the venture. Cost Control and Cost Accounting are essential parts of Cost Management. The principal objectives of Cost Control are to monitor project commitments and expenditures, and measure performance for the detection of variances from acceptable standards and from control budgets so that timely action can be initiated to minimize costs. Cost Control is evaluation of current costs and projection of future costs, rather than the reporting of actual costs. Cost Control is not Cost Accounting. The primary objectives of Cost Accounting are the determination, classification, analysis and reporting in useful detail of actual costs. Following are some considerations on Cost Management and Cost Control as practiced by Owners and Contractors of industrial projects, Mining and Metallurgical projects in particular. COST MANAGEMENT Functions Conforming with the requirements of Owner&apos;s Criteria, the principal Cost Management functions are to • evaluate estimates of project costs and establish budgets for a scope of work and schedule; conversely, evaluate the scope of work that can be executed most effectively within a budget and schedule. • promote investigations and comparative evaluations of alternate designs and plans to find the most cost effective way to execute a project and minimize its operating costs. • based on Cost Control and Cost Accounting input, evaluate and initiate appropriate actions to correct deviations from approved budgets. assess project economics, the effect of changes on project economics and, if necessary, revise Project Criteria to modify their impact on costs.

Jan 1, 1986

By Steven W. Hunt, Safdar A. Gill

Design and construction of temporary shafts for underground facilities often require evaluation of bottom stability due to rupture (blow-ins) caused by water pressure acting on a bottom plug. This paper provides an overview of shaft bottom stability evaluation methods for the case of a relatively watertight soil plug which overlies an artesian aquifer. Methods of considering plug perimeter shear, plug buckling and pressure relief are discussed. Minimum factors of safety are suggested. Future use of the shaft subgrade is also considered. Bottom plug failure case histories at several shafts are evaluated. This paper should be useful to project designers, ground support system design engineers and contractors involved with construction of shafts for underground facilities

Jan 1, 1997

By V. R. Miller

The Bureau of Mines conducted research on substitute brazing filler alloys with properties similar to those of silver filler alloys in an effort to conserve silver and reduce hazards from cadmium emissions. Experimental work was conducted first on the commercial silver brazing alloys BAg-I, BAg-la, BAg-2, and BAg-3 to establish criteria for evalu-ating the substitute alloys. Properties investigated included the wettability of copper, brass, and steel substrates, and the strength of joints made with the filler alloys. A series of experimental alloys containing 50 to 60 pct Cu, 20 to 28 pct Mn, and 17 to 30 pct Zn was prepared and evaluated, together with Cu-Mn-Zn alloys with 5 pct Pb or 2 pct Ni. Wetting properties and joint strengths were not as good as those for silver filler alloys, and the high application temperatures reduced the copper and brass base metal strengths. However, experimental alloys containing 70 pct Cu, 15 to 20 pct Mn, and 10 to 16 pct Sn had wetting and strength properties approaching those of the silver filler alloys. The application temperatures for these alloys were high-er than those for silver fillers, but not as high as those for the Cu-Mn-Zn alloys. With the Cu-Mn-Sn alloy fillers, copper alloy joint members are less deteriorated by recrystallization than when applying Cu-Mn-Zn alloys. The Cu-Mn-Sn system has potential for further devel-opment as a substitute brazing alloy system, particularly if the melting temperature can be reduced by the addition of other elements without decreasing the ductility and wetting.

Jan 1, 1983

By Walter Casquino

El presente trabajo señala las características, control de los proyectos mineros, así como el alcance de estudios, modales de ejecución, el factor humano y su relación con la empresa, entre otras recomendaciones.

Sep 1, 1980

By G. Paul

The mechanism of nodular crystallisation of graphite in the production of spheroidal cast Iron is not fully understood. The work reported In this paper confirms that in cast iron melts having a high Interfacial tension against the environmental atmosphere, the graphite tends to crystallise in nodules during solidification. The Influence of Interfacial tension between melt and solid graphite is similar.

By John G. Roscoe

Continental Materials Corp. operates two under- ground uranium mines in the Crooks Gap district of central Wyoming. Both mines are developed as slusher mining operations through vertical shafts with single level haulage to slusher pocket loading stations. In general, operations at both mines are similar except for depth and some minor details. The shafts are identical in cross-section, each with a 4 ½ x 5-ft hoisting compartment and a 4 ½ x 5-ft manway. Kimberley-type skips are loaded from measuring pockets through air-operated guillotine gates. The Seismic shaft is 245 ft deep and the Reserve shaft depth is 585 ft. The Seismic shaft was sunk in 1957 and the mine has been producing 200 tpd since 1958. The Reserve shaft was sunk in 1960 and the mine is still in the development stage. The hoists of both mines are equipped for semi-automatic operation; that is, they are mechanically controlled to perform a certain cycle of duty and then stop until another cycle is manually initiated. The Seismic hoist, however, was originally a conventional, manually controlled unit; the reserve hoist was installed as an automated system.

Jan 7, 1962

By Ralph Sweetser

THE Round Table. on Qualities of Pig Iron, under the auspices of the Joint Committee on Qualities of Pig Iron, which is made up of members of the American Institute of Mining and Metallurgical Engineers, the American Foundrymen&apos;s Association, the American Society for Testing Materials, the Gray Iron Institute, and the. Malleable Iron Institute, was held at the Palmer House, Chicago, Ill., on Oct. 1, 1935. PROCEEDINGS R. H. SWEETSER,* New York, N. Y.-Seven years ago last June we had a round table on qualities of pig iron1, and at that time the foundrymen were out with their battle-axes for the blast-furnace men, and the open-hearth men were doing the same thing. After that meeting there was really a determined effort to find out about the qualities of pig iron, and great progress has been made all along the line. This afternoon we want to have a frank discussion of the qualities of pig iron, whether it is the molten pig iron going into the steel plant, or cold pigs going to the different foundries. We ought to hear something from Dr. J. T. MacKenzie, who is chairman of the Joint Committee, and from Mr. R. E. Kennedy, the tech-nical secretary. J. T. MACKENZIE, t Birmingham, Ala.-As a result of that meeting in Chicago, there was considerable agitation in the Foundrymen&apos;s Association to develop a set of tests for pig iron. One of the difficulties was that nobody talked the same language on shrinkage, draws, live iron, dead iron, and so forth, which were the main com-plaints against pig iron. By request of a committee of the Foundrymen&apos;s Association, the Bureau of Standards ran a comprehensive set of tests that did develop the prin-ciples governing the optical pyrometer as applied to cast iron and pig iron. Then the Bureau went on further with the fluidity test, and developed a method for the absolute changes of volume at the freezing point.

Jan 1, 1936

By Adam Turcotte

Mining operations consume a considerable amount of energy, and while reduced energy consumption is desirable, it is not always clear how to achieve this goal. Understanding the opportunities to optimize energy consumption is crucial, and the key to understanding is visualization. One option is the Sankey diagram, which has been used for over 100 years to visualize the flow of energy, materials, or cost through various processes. However, there are drawbacks to this approach that must be addressed. In a Sankey diagram, each flow is represented by an arrow possessing a width proportional to the magnitude of the flow it represents. The diagrams show input flows, how energy is converted and into what form, and also output flows. As per the first law of thermodynamics, the total energy output is equivalent to the total energy input, so any energy that is not transferred to another process is considered to be wasted. These waste flows are depicted in Sankey diagrams and make it straightforward to associate energy sources, sinks and waste flows. Unfortunately, Sankey diagrams do not convey all information required to support practical decision making for redirecting individual energy flows. Based only on a Sankey diagram, it may become evident that a significant flow of waste heat is of the appropriate grade (temperature) and volume to meet an on-site heat demand currently being met with paid-for, possibly carbon intensive fuel. However without augmenting the Sankey diagram with 3D spatial, true geometric analysis, the practicalities of the concept or idea may not be fully appreciated. Another issue with a Sankey diagram is that the magnitude of the energy flowing between processes may have temporal fluctuation or variability on different timescales (diurnal, seasonal, interannual). Currently, Sankey diagrams only provide a static picture of energy conversion and consumption, so that, for example, 4 separate diagrams could have to be prepared for each season. A new energy flow visualization technique which we have called Sankey Trees has been developed. Process locations are defined within a 3D model of the site being studied, and the magnitude of the flow between each pair of processes considered is replaced with a time series. Branches of sustained and diminishing flows are represented through variation of the geometric properties of the branches of the trees. These branches are animated to indicate the direction of flow, and branch joints are used to indicate that a process is transporting one form of energy to multiple processes.

Aug 1, 2013