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By Michael McDonald

The cold-rolled steel output of cold-rolling mill (CRM) complexes are sometimes constrained by their batch annealing facilities (BAF). This paper examines a cost-effective solution to increasing capacity and quality of the BAF thereby making additional capacity available for CRM output. The solution involves applying a structured system of scheduling and operation to the BAF, using a proven level-2 software model. The system presented has been applied to a wide variety of BAF with all the leading furnace brands. Whether using traditional HN atmosphere or 100% hydrogen, peak performance can be achieved when using a properly configured, on-line, physical thermodynamic model. Given that it is not practical to place a thermocouple in each coil that is being annealed, various methods have historically been used to estimate the time required to properly anneal all the coils in the charge. This paper examines how the latest technology, in wide use throughout the USA, uses a physical thermodynamic model to shorten average cycle times, thereby increasing productivity and reducing energy consumption. The paper also examines the benefit of building thermodynamically balanced charges to further optimize the BAF operation and improve quality consistency by decreasing mechanical property variations.

Jul 30, 2018

The engineering company's participation in quality assurance in the mining industry is twofold. Not only must it have such a program to ensure the necessary high standards for its own design and construction of a minerals processing plant, but it is also responsible as the "engineer" for both the selection and the quality of purchased equipment which goes into that plant. It is in this latter role that the engineer finds the most difficulty, or controversy, since while it is relatively easy to control his own performance, this is not ncessarily so when dealing with companies, all with their own ideas or standards. The engineer has perhaps rather reluctantly become more involved with the quality assurance of purchased equipment. This is because he has been used to writing performance type specifications and expecting the equipment manufacturer to provide the degree of quality, and control of that quality, for the product to meet the specified operating conditions. However, this has sometimes placed the manufacturer in a difficult position since to remain competitive in today's market conditions, he cannot always insist on product improvements or options which may in the long run be vital to reliable operation of the equipment.

Jan 1, 1982

By Hui-gang Wang, Mei Zhang, Min Guo

Metal-doped Ni–Zn ferrite with spinel structure was directly synthesized from treated zinc-containing electric arc furnace dust (Zn-containing EAFD) by solid state reaction method, realizing the transformation of Zn-containing EAFD from solid waste to high value-added material. A certain mass of NiCl26H2O was added to the treated Zn-containing EAFD before calcination. Then the effects of the mass ratio of treated Zn-containing EAFD to NiCl26H2O (RTZE/N, g g−1) and calcination temperature on the synthesis and magnetic properties of as-synthesized samples were systematically investigated by X-ray Diffraction, Raman Spectroscopy and Physical Property Measurement System. It is indicated that RTZE/N and calcination temperature had important influences on the synthesis of single-phase spinel ferrite and their magnetic properties. Pure metal-doped Ni–Zn ferrite, which exhibited good magnetic properties of higher saturation magnetization (Ms, 60.5 emu g−1) and lower coercivity (Hc, 49.8 Oe), was obtained when the calcination temperature was controlled at 1100 °C for 2 h with RTZE/N of 1:0.9.

Mar 1, 2017

By G. Van Weert

The pellet reactor was developed approximately 20 years ago in the Netherlands for softening drinking water. Since then, some 35 plants have been built, ranging in capacity up to 8500 m3/h. Applications now also include removal of phosphates and fluorides and the production of metal carbonates and sulphides from waste streams. The pellet reactor consists of a fluidized bed, wherein the process solution is thoroughly mixed with the precipitation reagent at special inlet nozzles to give over-saturation of the compound to be precipitated. In water softening applications, the compound is CaCO,. In the case of nickel or other metal waste streams, Na2CO3 solution is added in sufficient amounts to precipitate metal (hydroxy) carbonate on the fluid bed particles. These grow typically to dense spheroids, which are removed when they reach 0.8 to 1.0 mm diameter. These spheroids are easily dewatered, free flowing and low dusting. The latter property is becoming an attractive advantage in connection with new plant hygiene regulations. The operation of a 60 cm diameter pellet reactor on nickel containing plating waste is described and the properties of the produced nickel carbonate spheroids are discussed.

Jan 1, 1993

By R. A. Busch, R. R. Backer, R. W. McKibbin

The Bureau of Mines conducted laboratory tests to determine the slur- ry transport and deposition properties of coal waste. A 188.5-ft pipe test loop was constructed with instruments to measure density, flow, and power and discharge, suction, and differential pressures. A 20-ton sample of Western coal waste was crushed and screened to 100 pct minus 1/2 in. Eight loop tests using this graded waste were run at slurry densities ranging from 1.15 (25 wt-pct solids) to 1.46 (60 wt-pct sol- ids). The resultant friction-pressure gradients ranged from 0.06 to 0.24 ft of water per foot of 4-in standard steel pipe. Particle-size degradation was significant. In a typical loop test lasting 25 min, the minus 200-mesh fraction increased from 19 pct to 34 pct. Deposi- tion tests showed that without the use of a flocculant, the slurries would not dewater when left to stand for 1 week. With flocculant, ad- ditional water was released; however, the settled slurries remained thixotropic. Further testing is necessary to determine their suitabil- ity for use as backfill material in active mines.

Jan 1, 1965

By S. J. Aresco

The Bureau of Mines has been active in promoting the purchase of coal for Government use under specifications that define the requirements in terms of heating value of the coal, expressed in British thermal units, and the composition as shown by proximate analyses. To these, when required, are added the ash-softening temperature, the free-swelling index, and the Hardgrove grind-ability index. Under most of these specification contracts the bidders guarantee the quality of the coal, and that guaranteed by the successful bidder becomes the standard of his contract. The deliveries are sampled in accordance with instructions4 issued by the Bureau of Mines; the samples are analyzed in the Bureau laboratory to determine whether the coal is of the quality guaranteed by the contractor; if it is not, a price adjustment is made. Analyses of the delivered coal and tipple samples (samples collected at mine tipples as coal is being loaded into railroad cars or trucks) provide valuable data for use in evaluating future bids. In addition, the continuous sampling of coal as delivered is a check on the practical results obtained in burning the coal.

Jan 1, 1965

By A. Warczok

The oxidation and smelting of chalcopyrite, bomite, chalcozine and pyrite has been studied under simulated flash smelting conditions. The results of copper sulphide oxidation show that under constant oxidation conditions, the degree of oxidation drops sharply when the particle size is increased above a given range. This critical size range varies typically between 200 and 500 pm depending on the oxygen content in the gas phase. For bomite, chalcopyrite and pyrite, the critical size range increases with increasing iron content in the mineral and with increasing oxygen content in the gas phase. The extreme case is observed for pyrite in pure oxygen, where there is no effect of the particle size on the degree of oxidization. Microscopical observations of the oxidized products show the influence of different factors on the mechanism of oxidation and fragmentation of the sulphide particles. Based on microscopical analysis and phase identification of the oxidized products, a model has been proposed for the oxidation and smelting of copper sulphide particles in suspended state. The mathematical model describing the sulphide particle oxidation is supported by the obtained results. Using this model, it is possible to describe the role of particular factors in the sulphide minerals oxidation.

Jan 1, 1992

By William J., Coulter

IN the early days of Colorado mining, between 1880 and 1900, when Leadville, Kokomo, and Robinson were boom mining camps, the entire area around Climax for a matter of fifteen miles was overrun with prospectors, so the mineralized outcrop at Climax was not unknown. The principal interest in minerals during this period was in gold, silver, and lead, and since the Climax outcrop showed none of these it drew little attention. Geology played an important part in bringing prospectors to the very edge of the Climax deposit. The Mosquito fault, which crosses near the base of Bartlett Mountain, continues as an important geological structure, at least as far as Leadville some twelve miles distant, and at the base of Bartlett Mountain the vertical throw on the fault is estimated to be between 2000 and 5000 ft. The sedimentary beds known to the Leadville district are all present on Bartlett Mountain to the north of the Mosquito fault, which cuts them off abruptly, and exposes the Pre-Cambrian rocks that underlaid them, so the prospectors, who were searching for gold, silver, and lead in the sediments

Jan 1, 1946

By D J. McDougall

Due to changes in the solid-state conditions of minerals in the rocks surrounding hydrothermal, contact meta-somatic or metamorphosed ore deposits, positive or negative thermoluminescent anomalies may be found in their vicinity. Several types of equipment which can be used for both quantitative and semi-quantitative measurements of the emission are discussed and compared. Methods of selecting, preparing and testing samples to ensure reproducible results are outlined, along with the kind of data which can be obtained from different types of equipment. The normal thermoluminescence of rock-forming min~ erals in the common rock types is noted, and variations in the solid-state conditions in the wall rocks which will cause marked increases or decreases of true thermoluminescence are outlined, as well as the thermolum-nescence-like emissions which are present in the vicinity of ore deposits. Introduction T HERMOLUMINESCENCE occurs when certain crystalline materials are heated to temperatures ranging between 180' and 400°C. The light emission can be ascribed to the release of electrons metastably trapped within the crystal lattice, with peak emissions taking place at temperatures which are more or less specific for a particular set of traps; the area under

Jan 1, 1965

"Cash flow modelling during project evaluation is enhanced when probabilistic methods are applied to the inputs. One of the important inputs is the quarterly production profile. Typically, the steady-state production profile provided to project evaluation practitioners is deterministic, with each quarter the same as every other quarter. This is unrealistic as actual production profiles from existing mines exhibit a range or quarter-on-quarter variance. Monte Carlo stochastic simulation of the production profile can be used to provide a range of possible outcomes, but how are these ranges selected? This paper describes the use of quarterly production variance from a large database of mines worldwide as a benchmark to inform the appropriate selection of ranges. The coefficient of variation is used to rank the production from mines, with quartile analysis applied to indicate industry best, median and worst variation. Due diligence of existing mines and evaluation of future production performance can be quantitatively assessed using this approach. Examples of the effect on value are provided.CITATION:Stewart, C A, 2016. Production variance benchmarks and their use in project evaluation and due diligence, in Proceedings Project Evaluation 2016, pp 201–213 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 8, 2016

By S. J. Aresco

The Bureau of Mines has been active in promoting the purchase of coal for Government use under specifications that define the requirements in terms of heating value of the coal, expressed in British thermal units, and the composition as shown by proximate analyses. To these, when required, are added the ash-softening temperature, the free-swelling index, and the Hardgrove grindablity index. Under most of these specification contracts the bidders guarantee the quality of the coal, and that guaranteed by the successful bidder becomes the standard of his contract. The deliveries are sampled in accordance with instructions3 issued by the Bureau of Mines; the samples are analyzed in the Bureau laboratory to determine whether the coal is of the quality guaranteed by the contractor; if it is not, a price adjustment is made. Analyses of the delivered coal and tipple samples (samples collected at mine tipples as coal is being loaded into railroad cars or trucks) provide valuable data for use in evaluating future bids. In addition, the continuous of coal as delivered is a check on the practical results obtained in the coal.

Jan 1, 1967

By John J. Sammarco

The U.S. Bureau of Mines is conducting research into computer-assisted mining, which requires investigation of new techniques for development and application of computer-based technologies. Today's technology can require significant effort in software development, as has become evident in the early stages of this Bureau research. Technologies for software automation, such as computer-aided software engineering (CASE), are available. This report explores CASE, its general features, and its importance in software development. Information is presented to assist in selection and application of the variety of CASE tools and methods for automating various stages of software development. When evaluating CASE for use, it is important to examine tools that support an organization's existing methods of software development. Support for existing hardware platforms must also be examined. Merely selecting a "good" CASE tool does not insure success. Thorough evaluation of implementing CASE is also critical. Subjects to evaluate for CASE implementation include organization culture, support from management and end users, training resources, and pilot projects. Organizations that benefit the most from CASE evaluate CASE features with respect to their needs and they properly implement CASE.

Jan 1, 1990

By Abu Syed H. Kabir, Mehdi Sanjari, Steve Yue, Jing Su, In-ho Jung

AZ31 magnesium alloy sheets were produced by high speed rolling (HSR) at 1000 m/min at a low temperature of 100 ?. A high reduction of 72% can be achieved in single pass. At the reduction of 30%, the microstructure was covered by shear bands and twins. When the reduction was increased to 49%, dynamic recrystallization (DRX) was clearly observed in the vicinity of shear bands and twins and the full recrystallization was seen at a reduction of 72%. In order to study the static recrystallization (SRX) behavior on the heavily twinned structure, annealing was then carried out at 200 ? on the as-rolled specimens at the reduction of 30% for different times. Static recrystallized grains were also firstly observed on shear bands and twins after 45 s and the microstructure was mostly fully recrystallized after 1 h annealing with a few retained large elongated un-recrystallized grains. Texture weakening was found during annealing on the heavily twinned specimens by SRX, but not during high speed rolling by DRX. In the present study, effect of DRX and SRX on microstructure and texture evolutions during rolling and annealing were compared.

Jan 1, 2015

By F. J. Sotillo

Mineral processing requires good classification of particles to attain an adequate separation of minerals. This is of utmost importance in the case of sulfide minerals. An ideal classification is obtained when particles are separated at a given mesh, which is fixed according to the characteristics of each sulfide ore. Under these ideal conditions, particles coarser than the mesh of separation are recovered in the underflow, whereas particles finer than the mesh of separation are recovered in the overflow. This paper presents the results of pilot plant tests that were performed on Ag-Pb-Zn and on Ag-Au Peruvian sulfide ores using a Density Separator, and the comparison of these results with those obtained using hydrocyclones, under similar operating conditions. The results show that the ratio of circulating load is reduced by 50% by using a Density Separator with respect to that obtained by using hydrocyclones. Moreover, the effect of the improvement in the separation efficiency obtained by using the Density Separator on the kinetics of flotation is also shown. Silver recovery of the Ag-Pb-Zn ore increased by 18% whereas gold grade in the concentrate of the Ag-Au ore is doubled.

Jan 1, 1998

By Alan G. Mayton

The Bureau of Mines conducted a study to (1) determine from laboratory tests the feasibility of a photographic method for determining reflec-tances that may be applied to measuring in-mine mineral reflectances and (2) formulate a procedure for collecting and analyzing the data. The method uses a 35-mm camera with automatic flash and a gray-scale re-flectance standard to collect on film the reflectivity data in under-ground mineral mines. After the film is processed, the data on the photographic prints are analyzed in the laboratory with a photometer. Test results show the photographic method can provide values of reflec-tance to within ±5 pet of full scale (full scale = 100 pet). The method's usefulness for determining reflectivity values, within similar limits of absolute percent error at the lower end of the scale, however, has not been completely resolved by the study and consequently warrants further investigation. The method offers an acceptable means for collecting and analyzing reflectivity data for reflectivities at the higher end of the scale, i.e., 50 pet or above; it should be used with caution when reflectivity values are below 50 pet. Four films were evaluated; all gave relatively satisfactory results.

Jan 1, 1987

By E. A. Sondreal

The Bureau of Mines investigated the use of lignite char for producing carbon disulfide; CS2 production rates were as high as when wood charcoal was used as raw material. The maximum space velocity for CS2 produced in the bench-scale study was 9,280 hour-1, reacting sulfur and lignite char at 792° C. The reaction temperature and the temperature at which the char was carbonized were the two most important factors in determining CS2 production rates. Increasing the carbonization temperature in nitrogen from 400° to 900° C advanced the temperature at which carbon disulfide was first produced from 550° to 850° C. The average activation energy for reacting chars with sulfur was 44,000 cal/g mole. The reaction was first order with respect to the partial pressure of sulfur. Increasing the rate of sulfur admission caused a decrease in rate of production at otherwise similar conditions. Rates were not affected by either char size or sodium carbonate catalysis. High space velocities at moderate temperatures using inexpensive lignite chars could offer an economic advantage in the manufacture of carbon disulfide provided that yields were attractive.

Jan 1, 1967

By A. L. Holmes

This presentation in the open pit session deals with the development of a phosphate rock strip mine by CF Industries, Inc., a company that does not presently mine in the Central Florida Phosphate District. Land acquisition, engineering, financing and environmental permitting activities were begun in early 1975; site preparation, environmental monitoring and dragline construction began in mid-1975. The operation is due on-stream in late 1978. The reserve acquisition, permitting, and financing could each easily be developed into a separate paper of interest. Each, however, has been covered before for other mining ventures with similar capital and environment requirements. For that reason, I have chosen to discuss what CF Industries, Inc. is, why it is entering this new sec-tor of the agricultural chemicals business, and, to keep at least some technical basis, what design modifications are possible when the total mine output is used captively and it is unnecessary to have the flexibility to meet the numerous transportation and customer specification considerations. In an attempt to show the size and complexity of the CF organization, a brief description of existing facilities should help show why the big interest in mining phosphate rock.

Jan 1, 1977

By S. J. Aresco

The Bureau of Mines has been active in promoting the purchase of coal for Government use under specifications that define the requirements in terms of heating value of the coal, expressed in British thermal units, and the composition as shown by proximate analyses. To these, when required, are added the ash-softening temperature, the free-swelling index, and the Hardgrove grindability index. Under most of these specification contracts the bidders guarantee the quality of the coal, and that guaranteed by the successful bidder becomes the standard of his contract. The deliveries are sampled in accordance with instructions4 issued by the Bureau of Mines; the samples are analyzed in the Bureau laboratory to determine whether the coal is of the quality guaranteed by the contractor; if it is not, a price adjustment is made. Analyses of the delivered coal and tipple samples (samples collected at mine tipples as coal is being loaded into railroad cars or trucks) provide valuable data for use in evaluating future bids. In addition, the continuous sampling of coal as delivered is a check on the practical results obtained in burning the coal.

Jan 1, 1966

By R C, K L. Rees, J S. J van Deventer

In contrast with previously published models for the carbon-in-pulp (CIP) process, the model proposed in this paper incorporates film transfer, intraparticle diffusion, simultaneous leaching, preg-robbing, the loading of multicomponent species, and the effects of fouling and changing cyanide levels. The rationale behind this comprehensive model is that changes in fouling and competitive adsorption along a CIP cascade affect the profiles of gold loading. As it is impossible to quantify all these non-ideal factors, a method is proposed whereby an imaginary species is postulated so as to combine all the competitive effects. A plant survey at the Telfer mine has shown that the mass loss due to a gravimetric analysis of the fouled carbon could be used directly to quantify this competitive effect. The degradation and consumption of cyanide along the Telfer CIP cascade enhance the loading of copper on to the carbon, which should be taken into account when modelling the gold profiles. It appeared that the effect of cyanide itself on the loading of gold was negligible compared with its effect on the copper. Evidently much more research is required on this topic in order to optimise CIP operations exposed to constantly changing conditions.

Jan 1, 1998

By L. A. Jordan, D. van Vuuren

A two-dimensional finite difference model has been developed to describe the reduction of kilogram quantities of dehydrated phosphogypsum. The model’s scope has been limited to focus on the heat transfer and reactions that occur within a mass of material contained in a vessel inside a furnace rather than also including the effects of heat transfer to the vessel. Changes in the heat transfer properties (k, ρ, and Cp) are incorporated as the composition of the mass changes as the chemical reactions progress. The model is validated against experimental data, with samples heated to 1000°C at 3°C min−1 while purging with nitrogen gas. A sensitivity analysis of model predictions to the pre-exponential factor of the reaction rate constant of the main chemical reaction and the thermal conductivity of the powder bed indicated that, at the envisaged process conditions, the behaviour of the system depends much more on the rate of heat transfer than on the rate of the chemical reaction. The model demonstrated a significant increase in accuracy when the thermal conductivity was modelled to increase linearly with temperature compared to assuming a constant value.

Oct 1, 2022