Search Documents

By Samuel Daniels

Aluminum-base alloys containing small amounts of copper and magnesium possess but ordinary physical properties as sand cast, but may be treated to give a remarkable range of tensile values and of Brinell hardness. The high-copper (4.5 per cent.) duralumins must be given a protracted treatment which in nature resembles the malleableizing of white cast iron; the low-copper (2.25 per cent.) duralumins develop an excellent combination of strength and ductility with a treatment which requires a maximum of 5 hr. to be completed. THE wrought alloys of aluminum with small amounts of copper and of magnesium have, with the development of the automotive and aircraft industries, sprung into prominence through the medium of duralumin; but the cast alloys remained in the background because their possibilities in the heat-treated condition were either not recognized or not fully investigated. In 1919, the Bureau of Standards published a preliminary survey1 of this field, which pointed out that, in general, the ultimate strength and the percentage of elongation of the alloys of aluminum with and without magnesium could be improved by so simple a treatment as heating to 932° F. (500° C.) for 2 hr., cooling in, air, and aging at room temperature for several days. British investigators, too, working with chill-cast material, found that " considerable improvement in the mechanical properties of copper-aluminum alloys' may be obtained from suitable heat treatment applied to castings."2 Jeffries and Gibson3 made the first contribution to the literature dealing exclusively with the heat treatment of sand-cast aluminum-base alloys, describing the effect of small additions or of combinations of copper, magnesium, and iron on the response to a short heat treatment comprising heating at 932° F. in a

Jan 7, 1924

By S. Abe

Various copper anodes to be electrorefined were subjected to a heat treatment comprising annealing at a temperature in the range of 700 °c to 1,000 °c followed by a slow cooling preferably on the order of about 150 °c, and using these heat treated anodes , a series of dissolution experiments were conducted under conventional electrorefining conditions. The results obtained have indicated that the above annealing/slow cooling process dramatically improves the dissolution activity regardless of the type of anodes. As an example, passivation times of l to 3 minutes in a standard test have been increased to more than 80 minutes by this innovated heat treatment. Other advantages sterning from the improved anodic activity include reduced electrical short circuiting which results in substantial labor effort in the tankhouse, reduced energy requirement, and reduced cost of processing anode slimes because the amount of anode slimes is reduced. In addition, this process gives rise to a dramatic change in the nature of anode slime layer formed in such a way that a comparable final cathode copper product can be achieved even from high-impurity copper starting material.

Jan 1, 1987

By Bijan Taheri, Behrouz Maghsodi, Monireh Heshami, Reza Kohan

A common problem recently encountered with the increase in the rate of input feed at Enrichment Plant 2 of the Sarcheshmeh Copper Complex is the loss of value to the tails, translating to lower recoveries. The feasibility of the direct transfer of part of the high-grade concentrate from rougher stages to an appropriate position along the circuit was studied, and two positions were proposed for direct transfer of the concentrate. One position was the feed flow into cleaner cells, and the other was the feed flow into the recleaner cell. The results indicated that transferring the concentrate from the first unit of the rougher stage to the feed flow into the cleaner cells was feasible, with no limitations, while the second position required the installation of a set of hydrocyclones. It was found that the transfer of concentrate to the proposed positions not only addressed the problem of limited cell capacity, resulting in debottlenecking of the circuit, but also improved metallurgical separation efficiency up to 1.4%.

By A. J. Martin

The Tri-State, or Joplin, zinc and lead mining district in south- western Missouri and adjoining, parts of Kansas and Oklahoma is one of the great mining districts of the world. It is in flat-lying or gently rolling agricultural country near industrial centers and coal, oil, and gas fields. The nearly horizontally, lying bedded rocks in which the ore bodies are found were originally limestone but are now largely chert containing minor percent- ages of dolomite and other minerals. The ore occurs in nearly vertical fis- sure zones, large and small, and in blanket (sheet-ground) deposits. The mining depth ranges from surface diggings to $50 feet. The average tenor of the ore mined, in recent years is much lower than that of ore produced in other large zinc and lead districts of the United States. Mining and mill- ing costs are low because of the shallowness of mining, amenability of ores to concentration, efficiency resulting from long experience of management and labor, and other factors. The operators comprise many small and medium-size producing companies and partnerships, as well as individuals and a few larger producers. About 7,000 men are employed in the mines and mills during normal industrial activity. The concentrates produced are sold f.o.b. the mill bins to local representatives of smelting companies at prices quoted on the Joplin market. The productive life of the district began with the discovery of lead near Joplin in 1848, but output was not large until after mining for zinc began near Granby in 1871. In most of the intervening years through 1945 the district produced more zinc than any other field, and it generally ranked third or fourth in the United States in lead production. Figures compiled from sources given later in this paper show a total output for the district from the beginning through 1945 of 20,755,020 tons of zinc concentrates and 3,334,057 tons of lead concentrates valued altogether at $1,110,058,581 in the mill bins. The output, in terms of recoverable metals, was 10,609,408 tons of zinc and 2,529,121 tons of lead, valued in all, at the average yearly market prices of the metals, at $1,691,282,419. During the 39 years (1907-1945) for which complete figures are available, the annual output of the district fluctuated from 23 to 66 percent of the total United States mine output of zinc and from 5 to 18 percent of the total lead; the averages for the period were 40 percent for zinc and 11 percent for lead. peak yearly production was attained in 1926, with an output of 423,800 tons of recoverable zinc and 102;117 tons of lead. Since that yoar the production rate has trended downward, accentuated at first by the depression in the thirties and later ameliorated somewhat under the stimulus of heavy demand and higher metal prices during World War II; the output in 1945 was 139,274 tons of recovorablo zinc and 23,556 tons of load. The above figures show the groat contribution made by the Tri-State district in the past toward the country's supplies of primary zinc and lead, cspecially zinc. However, the district's production is expected to decline both in quantity and in proportion of total United States mine output unless important discoveries are made. Ore exposed in mine workings and extensive exploratory drilling done in recent years within and without the productive The

Nov 1, 1946

By LaMar G. Evans

The rapid determination of uranium in ores by radiometric means was investigated by the Bureau of Mines. Among the various procedures and schemes tested, two showed most promise. They were the ratio scheme developed in the Bureau's Tucson, Ariz., laboratory and the equilibrium method developed by the Canadian Department of Mines and Technical Surveys. The ratio method is a simple, empirical procedure for classifying the state of equilibrium in ores by measuring their radioactivity by means of a Geiger-Muller counter under three different conditions, using filters. The principal merit of the method is in providing a clue as to the reliability of equivalent uranium determinations.

Jan 1, 1958

By E. D. Calvert

The room temperature tensile properties of commercially pure titanium and seven titanium alloys prepared by skull casting were determined in the as-cast and heat-treated conditions. Data were compared with property data from tensile tests on wrought alloys of the same compositions in the as-worked and heat-treated conditions. The alloys evaluated were Ti-5Al-2.5Sn, Ti-6Al-4V, Ti-6Al-4V-lSi, Ti-6A1-2Sn-4Zr-2Mo, Ti-6A1-6V-4Zr-4Mo, Ti-6A1-6V-2Sn, and Ti-11.5Mo-6Zr-4.5Sn. Test specimens were prepared from both static and centrifugal castings and from plate fabricated by forging and rolling vacuum-melted ingots. The data indicate that the alpha and alpha-beta alloys have strength properties in the as-cast condition that are reasonably close to the strength properties of their wrought counterparts in the as-worked condition. An exception to this was the Ti-6A1-6V-4Zr-4Mo alloy for which insufficient data were available to form any firm conclusions. Fine-grained cast structures of Beta III (Ti-11.5Mo-6Zr-4.5Sn) were shown to be generally stronger in the as-cast condition than the wrought alloy in the as-worked condition except for the yield strength of one structure that was unusually low. Heat treatment of this alloy produced properties that were unpredictable. Indications are, however, that optimization of heat treatment parameters for each cast structure could produce strength properties equal to that of wrought materials.

Jan 1, 1974

By Wang Xuewen, Bao Qingbao, Xie Jiacheng, Yan Zewen

This study puts forward a virtual memory cutting method based on the prediction of AFC shape. The integrated key technologies include the generation of virtual teaching cutting curve, the height adjustment strategy of front and rear drum, cutting height adjustment strategy, the reciprocating cycle of cutting technology and so on. Through the two algorithms, SVM and ELM, the form of the next working cycle can be obtained by rolling prediction using the form information of AFC in the first several circulations. Based on the obtained dynamic fluctuation of the form in the vertical and horizontal working faces, the position and cutting information of the shearer during its operation can be controlled and predicted in advance, the memory cutting template can be adjusted and modified in time. Employing this method, the more stable, accurate and timely memory cutting of the shearer under the uneven coal seam could be realized.

Aug 16, 2021

By J. Someehneshin

Nowadays along with population growth, industry development, consumption of mineral resources and the fact that the reserves on hand are running out, the depth of surface and underground mines for further exploitation are increasing. During recent years, in underground mining, the block caving method for low-grade and large-scale deposits has shown a growing rate of application. This method is very cost effective and economically affordable. The dimensions of blocks are one of the most important parameters which should be taken into account since it has been proved to have a great deal of effect on technical issues such as commencement of caving and mine design. Proper calculation of the length and width for a block in this method leads to proper caving and discharging which are the most important stages. Therefore, in this method, the calculation of the optimized dimensions (length and width) of blocks is not only important but also directly helps the productivity of extraction. In this study, firstly for the purpose of facilitation, some assumptions were considered and having used these assumptions for estimation of optimized length and width of block, a relationship based on rock mechanics and physics was explored. Furthermore, some necessary details were added to the said relationship and finally, it was transformed into an inequality. Solving this inequality provides us with the optimized length and width of the block. The explored relationship was analyzed with MATLAB software and the graphs thereof were drawn. In these graphs, each time one of the input parameters has been drawn up in a logical range so that it could be compared with previous states.

Aug 1, 2013

By Helênio Resende Silva Júnior, Thiago de Oliveira Mazzeu

O envelhecimento gradual das Baterias de Coque é um fato inevitável, sendo importante monitorar as condições dos fornos e das estruturas periféricas para maximizar sua vida útil. A Paul Wurth desenvolveu uma metodologia de diagnose que avalia as condições dos elementos principais que compõem as plantas de Coqueria, dentre elas: estrutura da alvenaria refratária, estruturas e componentes metálicos, análise do controle térmico e regime de pressões, conjunto das máquinas móveis. Através de inspeções visuais e coleta de informações de processo e rotina adotada pela equipe de preservação da planta de Coqueria, são elaborados procedimentos e recomendações que visam à extensão da vida útil do equipamento. A Diagnose é uma técnica que auxilia as equipes de Coqueria a entenderem em que situação o equipamento se encontra e contribui com as melhores práticas adotadas no mercado para o prolongamento da vida útil. Ela deve ser repetida com frequência de modo a atualizar a situação da Bateria de Coque, verificar o efeito das ações tomadas pela equipe de preservação e propor novas recomendações. A Diagnose ainda permite identificar a idade real de desgaste das estruturas da Bateria em comparação com sua idade cronológica, permitindo que as usinas planejem investimentos de maior porte.

Oct 1, 2019

By Yap Chu-Phay

IN 1923, when the writer began his studies in metallurgy, he came upon an article by Professor Honda on the, Equilibrium Diagram of the Iron-carbon System, 1 which made a profound impression on him. What interested him most was this sentence: "In the recent diagram of the iron-carbon system, the solidus is usually shown as a curve bending considerably downward. But it can be shown by thermodynamics that if the liquidus is straight or slightly curved, the same must also be true for the solidus. Hence, in my constitutional diagram, the lower portion of the solidus is slightly bent upward." Ever since then the writer has been interested in thermodynamics, especially chemical thermodynamics. The applications of thermo-dynamics to the metallic systems have been, in the writer's opinion, sadly neglected, although we continually use the phase rule in our study of equilibria in the liquid and solid states of metallic alloys. Many investigators, among whom may be mentioned Heycock and Neville, and s Honda and his coworkers, have applied the simple Raoult-van't Hoff law of depression of freezing point, mainly to determine the heat of fusion, but no attempt has been made to investigate the applicability of the thermo-dynamic laws of solution (as opposed to the laws of solution derived from other sources) to metallic systems" showing either limited or complete solid solutions. Perhaps the reason for this neglect is that until recently there have been so few reliable data on the solidus, which is much more difficult to determine than the liquidus. The writer has under way at the present time an investigation of a number of systems, the solidi of which have been more or less reliably determined. Recently, the writer has not only shown the valid applicability of the thermodynamic laws of solution as applied to the system antimony-bismuth but has also suggested a method of attacking problems involving complete and incomplete equilibria.2 In the present paper, the same method of approach is employed. For convenience, we shall divide this paper into two parts:

Jan 1, 1931

By Sheryl D. Gallagher

The project consisted of filling an abandoned underground limestone mine to facilitate construction of a new entrance ramp to I-470 in Lee?s Summit, Missouri. Due to collapse of mined areas near the project site, design included determination of the limits of remediation for the project and minimum construction requirements for mine infilling. The Judy Company, contractor selected for the mine infilling, experimented in the laboratory with several grout mixes to determine the appropriate mix for the project. Infilling was accomplished from the ground surface, and camera observation was used to monitor the barrier wall construction and infilling process. It was discovered that some of the mapped rooms were larger and some were smaller than indicated on the construction plan.

Jan 1, 2009

By Scott A. Shapkoff

High strength cable strand supports are predominately used as a supplemental means of ground control in longwall and development operations in the U.S. The advantages of cable strand supports have been documented and include flexibility, strength, and ease of installation. Since the majority of cable supports installed in the U.S. today are partially grouted, and this same segment of supports has no inherent installed tension, the supports are considered currently arbitrarily strictly supplemental and therefore, cannot currently be deemed primary support (in most mining districts). This paper details and discusses two distinctly different configurations and the technical advantages of active partially grouted cable supports for certain primary support applications. The evolution of the designs for both systems is highlighted. Field data illustrates the amount of active load in relationship to installed torque and the affects that component variables have on this load measurement. Roof control patterns using active cable supports are examined as alternatives for combination patterns using primary and supplemental systems. The importance of maintaining consistent installation procedures plays an important role in the level of performance of the system. Economics comparing the installation of active cables with other primary/supplemental patterns is also included.

Jan 1, 2006

By C. H. Bucknam

Principles of Green Chemistry provide useful guidance for sustainable mineral process development. Laboratory bench scale testing was carried out using pregnant cyanide leach solutions, and a number of commercially available mercury precipitation reagents were compared using jar testing to determine the most efficient and selective reagents for mercury precipitation. The most efficient reagent identified was sodium polymeric thiocarbonate (NaPTC).Coagulation experiments with fine diatomaceous earth resulted in a stable precipitate, with good settling properties. On line monitoring of the mercury in solution is recommended for process implementation to conserve reagent removing approximately 90-95% of the mercury with minimal silver and negligible gold losses.

Jan 1, 2004

By E. G. King

This report contains experimentally determined heat-content values for cerium dioxide and Columbium (niobium) dioxide in the temperature range from 298° to 1,800° K. There are no previous similar data for Columbium dioxide, and those for cerium dioxide have an upper limit of 373° K. The heat-content and corresponding entropy-increment data are presented in tabular form. Equations were derived to represent the heat contents and heat capacities. The data for cerium dioxide are entirely regular, but those for columbium dioxide show two previously unreported anomalies at 1,090° and 1,200° K.

Jan 1, 1961

By Y. Shu, A. R. Laplante

"A laboratory Knelson Concentrator (LKC), 7.5 cm in diameter, was used to study the performance of a similar unit at plant scale, 76 cm in diameter, This paper reports on sampling and assaying procedures and problems, and discusses the performance of the plant unit.The sampling procedure was based on the extraction of large samples, 5-15 kg, and their complete processing with a LKC, to characterize size-by-size performance. The procedure yielded reliable estimates of overall gold assays, after blatant assaying errors were corrected. The plant centrifugal unit concentrate was sampled in situ, which yielded very erratic grades, with a large overall negative bias. Due to the very heterogeneous nature of the concentrate, which can be linked to flow patterns in the riffles of the unit, it is recommended that for future testwork, the concentrate be recovered separately, blended and then sampled.The plant centrifugal separator, when operated at a feed rate of 25 t/h, yielded total and free gold recoveries of 41 % and 62%, respectively. This is much lower than previously reported data, and suggest that at 25 t/h, the unit is overloaded. However, recovery did not decrease with time over a loading cycle of 2 hours, which suggests that present loading cycles, generally 1 hour, can be significantly increased. INTRODUCTIONThe study of gold gravity circuits is plagued with the statistical problem of determining the behaviour of particles occurring with a very low frequency. This problem becomes particularly acute with increasing particle size. For example, considering the average weight of a gold flake in the 840-1200 µm (20/28 mesh) to be about 5 mg (Banisi et al, 1991), a reasonably high grade feed of 10 git would require, for a relative error (standard deviation) of 10% on grade, 100 particles, that is 0.5 g of gold, or 50 kg of 840-1200 µm material (a Poisson distribution is assumed). Gy's formula, for the same data, yields a weight of 33 kg, with a shape factor of 0.1 and a size distribution factor of 0.5. Both results are comparable; to obtain the suggested weight of material, a stream containing 5% weight in the 840-1200 µm would require 1 tonne samples (of unsized material). The problem rapidly disappears with decreasing particle size. Still with Banisi et al's data, a gold flake in the 300-420 µm range averages 0.5 mg in weight; the same 10% error on grade corresponds to a weight of 5 kg. Gy's formula for the same size distribution and particle shape factors as above predicts a required mass of 1.4 kg. This would correspond to an unsized sample weight of 10 kg with 14% weight in the 300-420 µm, for example."

Jan 1, 1992

By T. T. Chen

Canadian Electrolytic Zinc has developed the "cement-stabilization of jarosite residue" Garofix) process to stabilize zinc plant jarosite residues for disposal. The cement-jarosite mixtures cure quickly, have good mechanical strength and low hydraulic permeability; they possess good neutralizing capability and chemical stability. In the jarofix process, Portland cement partly decomposes jarosite to form (SO4MOH)12.nH2O, ferric hydroxide and an alkali sulphate. Approximately 40% of the jarosite reacts in mixtures containing 30% cement. The jarofix product also contains various Ca-Al-Fesilicate-sulphate-hydrate phases and gypsum, which bond the individual particles together imparting mechanical strength and reducing the permeability. Most of the reactions take place in the first few hours of curing. Ammonium jarosite is slightly more reactive than sodium jarosite but releases NH3 gas; water-soluble Zn in the jarosite residue is stabilized in the cement reaction products.

Jan 1, 1996

In October 1993 it was decided to undertake the fourth phase of mining at Big Bell. This decision followed the exhaustion of open pit reserves in January 1993. Two stages of mining were proposed for the new underground mine. The initial stage would mine the remnant ore, consisting of the rib and crown pillars and lower grade ore on the hangingwall and footwall side of the old open stopes, which were mined from the 1930s to 1950s. Most of the old open stopes were backfilled with either deslimed mill tailings or development mullock, both of which were economic to recover. However, the mineable ore from this resource was difficult to evaluate. The second stage focused on mining ore outside the remnant areas and was initially proposed as a Core and Shell method under a caving hangingwall. This method has since been superseded with sublevel caving, in part due to the very high and deviatoric stress conditions encountered at Big Bell and the relatively long mining cycle required for open stoping. The problems and challenges discussed in this paper will cover the identification of remnant ore reserves, dewatering the old workings, and remnant mining.

Jan 1, 1998

The war story of the engineer corps at home and in France is told officially for the first time in the advance sheets of the War Department's brief history of American war efforts. Many of these accomplishments have been published before as isolated incidents, but they gave no idea of the extraordinary duties modern warfare has laid upon engineering troops. In the engineering units that reached the other side, there were seven regiments and two battalions of railway construction engineers; five battalions for maintenance of way; two battalions for maintenance of railway equipment; four regiments and one battalion to operate the main American railways in France; three regiments to operate light railways and their repair shops; two regiments to operate the regular railway repair shops; two regiments and six separate battalions on general construction work; two regiments for storing and transporting engineer supplies; a forestry regiment; a light-railway construction regiment; a roadbuilding regiment; a water-supply regiment; a mining regiment; a quarrying regiment; a technical regiment for surveying and sound ranging; three survey and printing battalions; two railway transportation battalions; an electrical and mechanical regiment; several separate companies to operate cranes; a camouflage service; five inland waterway companies, to operate canal boats and the like; five pontoon trains and a pontoon

Jan 6, 1919

Develop a full-length-anchored roof bolt that is economical, nontoxic, nonflammable, and non-allergenic. Approach Grout roof bolts with a storable mixture of ultra-fast setting inorganic cement and water. How It Works A loose mixture of dry cement powder, and pinhead-size water droplets encased in waxy globules, are pack-aged in sausage shaped cartridges for storage and use. After the cartridge is inserted Into a drilled hole, the roof bolt is thrust In and rotated to mix the cement and water. The cement hardens in seconds, providing usuable anchoring strengths in minutes. Prior to filling of the sausage shaped cartridges, the microcapsules of water are Intimately mixed with the dry cement. The currently used grouting consists of a mixture of one part water (minimum) with three parts alpha-type gypsum cement and a minor amount of accelerator.

Jan 1, 1978

By D. Havlena, A. S. Odeh

The material balance equation used by reservoir engineers is arranged algebraically, resulting in an equation of a straight line. The straight line method of analysis imposes an additional necessary condition that a successful solution of the material balance equatiott should meet. In addition, this algebraic arrangement attaches a dynamic ineuning to the otherwise static material balance equation. The straight line method requires the plotting of one variable group vs mother variable group. The sequence of the plotted points as well as the general shape of the resulting plot is of utmost importance. Therefore, one cannot progrm the method entirely on a digital computer ar is usually done in the routine solution of the material balance equation. If this method is applied, then plotting and anaIysis are asential. Only the appropriate equations and the method of analysis and interpremtion with comments and discussion are presented in this paper. Illustrative field examples for the various cases treated are deferred to a subsequent writing. INTRODUCTION One of the fundamental principles utilized in engineering work is the law of conservation of matter. The application of this principle to hydrocarbon reservoirs for the purpose of quantitative deductions and prediction is termed "the material balance method of reservoir analysis". While the construction of the material balance equation (MBE) and the computations that go with its application are not difficult tasks, the criteria that a successful solution of the MBE should fulfill have always been a problem facing the reservoir engineer. True and complete criteria should embody necessary and dcient conditions. The criteria which the reservoir engineer uses possess a few necessary but no sufficient conditions. Because of this, the answers obtained from the MBB are always open to question. However, the degree of their acceptability should increase with the increase in the number of the necessary conditions that they should satisfy. Generally, the necessary conditions commonly used are (1) an unspecified consistency of the results and (2) the agreement between the MBE results and those determined volumetrically. This second criterion is usually overemphasized. Actually, the volumetrically determined results are based on geological and petrophysical data of unknown accuracy. In addition, the oil-in-place obtained by the MBE is that oil which contributes to the pressure-production history,' while the volumetrically calculated oil-in-place refers to the total oil, part of which may not contribute to said history. Because of this difference, the disagreement between the two answers might be of paramount importance, and the concordance between them should not be overemphasized as the measure of correctness of either one. In this paper, a third necessary condition of mathematical as well as physical significance is discussed. It is not subject to any geological or petrophysical interpretation, and as such, it is probably the most important necessary condition. It consists essentially of rearranging the MBE to result in an equation of a straight line. This straight line method of the MBE solution has invalidated a few long time accepted concepts. For instance, it has always been advocated that if a water drive exists, but one neglects to take it into account in the MBE, the calculated oil-in-place should increase with time. The straight line method shows that in some cases, depending on the size of the neglected aquifer, the calculated oil-in-place might decrease with time. The straight line method requires the plotting of a variable group vs another variable group, with the variable group selection depending on the mechanism of production under which the reservoir is producing. The most important aspect of this method of solution is that it attaches a significance to the sequence of the plotted points, the direction in which they plot, and to the shape of the resulting plot. Thus, a dynamic meaning has been introduced into the picture in arriving at the final answer. Since the emphasis of this method is placed on the interpretation of the sequence of the points and the shape of the plot, one cannot completely automate the whole sequence to obtain "the best value" as normally done in the routine application of the MBE. If one uses the straight line method, then plotting and analysis are musts. The straight line method was first recognized by van Everdingen, et al,2 but for some reason it was never fully exploited. The advantages and the elegance of this method can be more appreciated after a few cases are carefully treated and worked out by it. SOLUTION OF THE MATERIAL BALANCE EQUATION SATURATED RESERVOIRS The MBE for saturated reservoirs written in AIME symbols is