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By S. G. Gendler

The choice of ventilation schemes in the Northern Mujsky railway tunnel and definition of the nec-essary quantities of air ensuring regulated radiation conditions in the tunnel system has been accomplished. The influence of natural draught on the stability of tunnel ventilation has been estimated. The design of a portal venti-lation gate allowing minimal influence from natural factors is described. The dependence of pressure loss in the sliding ventilation gates on their spanning value of the vehicle tunnel section has been determined. The selection of parameters for an atmospheric air heating system in winter has been carried out. The operation regimes of air heaters, dependent on the temperature of atmospheric air, have been established.

Jan 1, 2009

By R. W. Smith, A. M. Raichur, M. Misra

Mycobacterium phlei has very good potential as a hematite flotation collector. The flotation recovery of hematite is dependent upon the solution pH and concentration of the microorganism. The critical pH for maximum recovery of hematite is around three, which corresponds to the point of zero charge of the microorganism. An excellent correlation between the flotation recovery and bacterial adhesion on hematite is observed. The adhesion of Mycobacterium phlei on hematite can be described by the potential energy of interaction calculations using an extended DLVO theory.

Jan 1, 1994

By Emma Arakelova

?2?2 (98 %) vapour passed through a reactor at 25Pa where a Zn? target was placed at 273K- 373?. Experiments were carried out on a flow- type vacuum device. ?2?2 decomposition on Zn? surface accompanied by formation of a Zn-containing volatile complex which transferred to the gas phase, and Zn? deposited on a substrate at condensation. As the substrate, five sequentially located quartz cylinders were used at 293K- 423 K (?n). Decomposition of the Zn-containing complex on quartz substrates carried out as a first- order reaction. ?The complex decomposition constant (??) increased with the substrate temperature (?n=293 K, ??=7.05 sec-1;?n = 373 K, ?? = 87 sec-1;?n = 423 K, ?? =158 sec-1). ?The complex decomposition constant did not practically vary when the target temperature increased; the complex formation rate increased slightly.

Jan 1, 2006

By Frank Foote, Willard L. Bruner, Eric R. Jette, Y. New york

The alloys of gold and iron were investigated in 1907 by Isaac and Tammann,l who determined the thermal diagram for the entire system by thermal analysis and microscopic examination. They also reviewed the previous literature. Since that time the present authors have been able to find only two additional references. Guertler and Schulze2 examined the electrical resistance of iron alloys containing up to 40 per cent by weight of gold between 0" and 200" C.; the alloys were in the form of wires. The main result of this work was to confirm the solid solubility limit found by Isaac and Tammann; namely, about 20 per cent Au. More recently, Shih3 has examined the magnetic properties of gold alloys containing up to 10 weight per cent iron and particularly the range below 5 per cent. The alloys in the lower range were found to be paramagnetic; the 10 per cent alloy was ferromagnetic. The present investigation was undertaken to determine the solid solubility limits at various temperatures, particularly below the a-y transformation point of iron, since these solubilities are of some importance in connection with the working of the alloys in the manufacture of certain "grey" and "blue" golds. Materials and Methods The gold was obtained from the U. S. Metals Refining Co. and contained 99.99+ per cent Au. The electrolytic iron had been annealed in hydrogen and contained impurities as follows: P, 0.035; Si, 0.001; S, C, Mn, Cu, each 0.01 per cent. Weighed quantities of the two metals were placed in small crucibles lined with pure sintered MgO; a saturated solution of magnesium nitrate

Jan 1, 1934

Efficacy of Enhanced Gravity Separator in Processing Indian Iron Ore Slime The slime sample was subjected to concentration using Falcon concentrator for their enrichment. The effects of three important variables, eg bowl rotation frequency, back water flow rate and per cent solid were studied on the process performance. Increasing the rotation of the Falcon bowl, enable more material to the underflow by increasing the yield, whereas, the iron content decreases steadily with increasing the rotation of the bowl. The increase in the back water flow effectively removes the clay materials from the underflow at the expense of the yield. Similarly, increasing the per cent solid concentration in the feed produces a better product both in terms of yield and Fe content. Results show that EGS/Falcon can be used for processing Indian iron ore slime and producing pellet grade concentrate.

Sep 13, 2010

By L. Nahai

In an exchange of views with the Program Chairman for the Technical Session on Industrial Minerals and Investment in Foreign Countries, it was agreed that it would be more interesting to approach the problem of mineral investment in foreign countries in a more general framework and not confine it to industrial minerals. Therefore, this Bureau of Mines report is proposed to examine current attitudes toward investments in foreign mineral resources and restraints that they impose on investments necessary to assure supply for future global mineral needs.

Jan 1, 1976

By Walter F. Atkins

Fair market value, in the legal sense , is the price which a prudent and knowledgeable buyer and a prudent and knowledgeable seller, acting without constraint or compulsion , will agree upon to exchange an asset. In the ordinary commercial or engineering usage, the term may imply simply the market value or a reasonable and equitable price. The engineer evaluator who is called upon to express an opinion about the fair market value of an asset may be able to base his estimate on the sale price of similar assets or on the market values of stock. Frequently such indicators of value are not available and the evaluator must devise other means of appraisal. Mineral resource properties may be thought of as having value by virtue of the existing or potential ability to produce at a profit. Conventional procedures permit the computation of the present value of future revenues having due regard for the time value of money and the risks attendant upon the realization of the venture. Such computations have gained wide acceptance as a basis for the estimation of fair market value.

Jan 1, 1977

By Charles L. Mantell, Kurt Straler

The hydrogen reduction of Cr2O3 to chromium metal was found to be feasible at very low water-vapor concentrations, corresponding to dew points of -38° to -24°C, over a temperature range of 1130" to 1490°C. Hydrogen reduction under these conditions was predicted by the calculated equilibrium curves which also indicated that CrzOs is reduced directly to chromium without forming the intermediate oxide, CrO. This reduction path was confirmed by X-ray diffraction analysis. The percent reduction of Cr2O3 at each reaction temperature was constant with time, suggesting an inhibiting effect of water vapor. A small increase in the residual water-vapor concentration of a single temperature, 1490°C, strongly retarded the rate of reduction This effect was expressed by an empim'cal equation which indicated a direct relationship between "distance from equilibrium" and the rate of reduction. me effect of temperature over the range of 1130" to 1490°C was expressed in an Arvhenius plot of log rate vs reciprocal absolute temperature. From this curve the apparent enthalpy of activation was found to be 29,600 cal. Based on the hypothesis that the rate of reductiun is contvolled at the oxide-metal interface, an over-all rate equation consistent with the experimental data and the thery of absolute reaction rates was formulated. A simplification of this expression to an Arrhenius equation was justified by the overriding effect of temperature on the rate of reaction for the minimum water-vapor concentration range. MOST of the metals in Subgroup V1 of the periodic table can be prepared commercially by direct reduction of their oxides by hydrogen or carbon monoxide, at temperatures considerably below the melting points of both the metals and their oxides. Chromium is an exception, being generally reduced from its ore, Cr2O3 . FeO, by silicon in an electric arc furnace which operates above the melting point of the Fe-Cr alloy or above the melting point of chro- mium if a chromium oxide be the starting material. In reduction of chromium oxide by hydrogen, either reduction does not occur at all or the rate of reduction is extremely slow. Theoretical considerations based on the high, exothermic, free energy of formation of Cr2O3 compared to the oxides of the other Subgroup VI metals, molybdenum, tungsten, and uranium, would also suggest a slow rate of reaction and a high activation energy. Interest in the direct gaseous reduction of fine-powdered ores in fluidized beds was considered justification for examination of this reaction. In order to develop a basis for a continuing study of the commercial feasibility of the direct gaseous reduction of chromite, a study of the kinetics of the reduction of Cr2O3 with hydrogen was undertaken. To the authors' knowledge no accurate kinetic data for this reaction have been obtained. Neither has an activation energy been determined nor has an attempt been made to establish a mechanism of reaction. LITERATURE Maier10 compared the data of I. Y. Granaat,6 H. von Wartenburg and S. Aoyama, and G. Grube and M. Flad7 with that derived from calorimetric and ther-modynamic properties for the equilibria for the reduction of Cr2O3 with hydrogen. These results, plotted as the log of the equilibrium constant vs absolute temperature for the reduction of Cr2O3 and the intermediate oxide, CrO, to chromium, show agreement between the differently derived data. In both cases the equilibrium constants were extremely low. Maier showed that, over a temperature range of 1000° to 2000°K, Cr2O3 is more readily reducible than CrO. Granat assumed that CrO was preferentially formed from Cr2o3 above 1100°C. Grube and Flad's analysis of their reaction products in the 895" to 1000°C range indicated the coexistence of only Cr2O3 and chromium. The hydrogen reduction of the other Subgroup VI metals, molybdenum, tungsten, and uranium, shows that reduction of the higher oxide proceeds through all of the intermediate oxides before being reduced to the metal. Since evidence pointed to an anomaly in the reduction behavior of Cr2O3, the authors investigated the reduction path of Cr2Os.to chromium. This was done theoretically with more recently available free-energy data and experimentally by X-ray diffraction analysis. This work reinforces Maier's conclusion.

Jan 1, 1964

By E. P. Youngman

In the Unfederated Malay States, with the exception of Johore, the rights of suzerainty, protection, and administration were transferred by giam to the British Government in 1909. In the States of Kelantan, Trengganu, Kedah, and Perlis, the rulers are assisted by State Councils and by British advisers appointed by the British Government.3 With respect to Johore, the largest, richest, and most highly organized of the Malay States not in the Federation, the treaty of December 11, 1885, with Great Britain, defined the relations of the State to the British Govern- ment and allowed the Maharaja to assume the title of "Sultan"; an amendment to this treaty (May 12, 1914) provided that the Sultan should be advised by a British officer, the General Adviser. ...... The political organization of the States is reflected in the mining legis- lation, Johore being the only one having a comprehensive code. The mining enactments now in force, according to the High Commissioner for the Malay States, are as follows:

Jun 1, 1932

The overall objective of this study is to gather operational data from selected surface coal mining systems in the United States, and to assess the potential production and economic capacity of the systems. The study includes: four mines, each using a different mining technique and different equipment. One mine was selected from each of the major coal fields: Midwestern, eastern,, northwestern, and southwestern. The Midwestern Mine is located in the Central Plains and produced 1.45 million tons of raw coal during the study year The Midwestern Mine uses the area mining or box-cut technique. A large in-pit shovel and a bucket wheel excavator are used to remove the overburden. Coal is removed by a loading shovel and transported to the dumping point by large off--highway trucks.

Jan 1, 1975

By G. A. Kordosky

Solution mining followed by solvent extraction-electrowinning (SX-EW) is one possible way to economically extract copper from ore bodies which cannot otherwise be profitably exploited. Published costs for the unit processes of SX and EW are out of date especially in view of the newer reagents now available and the newer circuit configurations, This paper updates the costs for SX-EW in 1985 dollars and also discusses some of the trade-offs which must be made when designing an SX-W plant.

Jan 1, 1986

By E Nye and T Schroeter, B Muir, M Kitson, M Gonzalez, D Mares

The single track North Strathfield Rail Underpass (NSRU) consists of a dive structure either end of a 148 m long driven tunnel skewed under three live railway tracks. The tunnel is 8 m high, 9 m wide, with a horseshoe profile, excavated by full face using a road header. Ground cover varied between 2.5 m to 3.5 m. Settlements were 5 mm to 15 mm (the latter due to a dyke). A one pass synthetic fibre reinforced shotcrete lining was installed (no lattice girders or steel sets were used). A system of automated robotic total stations was used to provide real time monitoring of the rail track and associated ground formation. No disruption to train services occurred.CITATION:Gonzalez, M, Kitson, M, Mares, D, Muir, B, Nye, E and Schroeter, T, 2014. The North Strathfield Rail Underpass – driven tunnel design and construction, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 369–374 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By W. K. Collins, C. L. Dahlin, D. C. Dahlin, W. K. O’Connor, G. E. Rush

Direct mineral carbonation has been investigated as a process to convert gaseous CO2 into a geologically stable final form. The process utilizes a slurry of water, with bicarbonate and salt additions, mixed with a mineral reactant, such as olivine (Mg2SiO4) or serpentine [Mg3Si2O5(OH)4]. Carbon dioxide is dissolved into this slurry, resulting in dissolution of the mineral and precipitation of magnesium carbonate (MgCO3). Optimum results have been achieved using heat pretreated serpentine feed material and high partial pressure of CO2 (PCO2). Specific conditions include: 155°C; P002=185 atm; 15% solids. Under these conditions, 78% conversion of the silicate to the carbonate was achieved in 30 minutes. Process mineralogy has been utilized to investigate the appropriate feed characteristics, identify the process products, and interpret the mineral dissolution and carbonate precipitation reaction paths.

Jan 1, 2001

By C. C. Russelll, V. T. McLemore

The Metals Mining Sector of the Acid Drainage Technology Initiative (ADTI-MMS) addresses technical drainage-quality issues related to metal mining and related metallurgical operations, for future and active mines, as well as, for historical mines and mining districts. One of the first projects of ADTI-MMS is to develop a handbook describing the best sampling, monitoring, predicting, mitigating, and modeling of drainage from metal mines, pit lakes and related metallurgical facilities based upon current scientific and engineering practices. One of the important aspects of planning a new mine in today’s regulatory environment is the philosophy of designing a new or existing mine or expansion of operations for ultimate closure. The holistic philosophy taken in the ADTI-MMS handbook maintains that sampling and monitoring programs should be designed to take into account all aspects of the mine-life cycle. Data required for the closure of the operation are obtained throughout the mine-life cycle, from exploration through post-closure.

Jan 1, 2004

By Oliver Bowles

The manufacture of lime is one of the oldest industries. Plants are distributed widely and furnish an essential raw material for numerous industries. The use of lime by the building trades, in agriculture, and in hundreds of manufacturing and chemical processes has created demands for a large production and has necessitated exhaustive research on methods of manufacture and uses. The bibliography of lime is an extensive one, but for the most part each publication has dealt with only certain operations. The purpose of this paper is to present a general picture of the industry as a whole. The abundant literature has been abstracted and quoted freely, and the National Lime Association has rendered valuable assistance in furnishing data for certain sections. Publications containing more detailed information on the various branches of the industry are referred to in the footnotes and in the bibliography.

Jan 1, 1936

By S. A. Bortz

This report presents the results of an extensive laboratory testing program to determine the physical properties of shotcrete including the use of fast-set agents, controlled set cements, and both wet and dry shotcreting equipment. Shotcrete was placed under simulated field conditions using the dry and wet processes. Mechanical properties obtained for accelerated and nonaccelerated shotcretes include compressive, flexural, and shear strength, elastic modulus and Poisson's ratio, and shear and tensile properties of shotcrete bonded to coal, sandstone, and shale. Physical properties measured were unit weight and permeability to methane gas. The data show that rapid setting shotcrete has the potential for improved coal mine ground control. There is no clear evidence that either wet or dry process shotcrete is superior to the other; however, indications are that regulated set cement is preferred to cement containing fast-setting admixtures.

Jan 1, 1973

Volume 2 presents the results of studies of Phelps Dodge Corporation's tailings embankments numbers 1West and 2 West, at Morenci, Ariz. The work involved compilation and description of pertinent factors relating to the physical features and operational characteristics of the facility, including information on embankment construction practices; investigation and research of the general geologic and seismicity characteristics of the site and vicinity; limited field exploration and materials sampling and testing at the site; installation and limited monitoring of piezometers, surface movement markers, and slope indicator casing; limited laboratory testing of materials to evaluate the basic index and engineering properties of the embankment and tailings materials; selected engineering analyses of the embankment for various types of potential "failure" conditions; and includes appendices.

Jan 1, 1974

By Prasenjit Basu

Drilled displacement piles are being increasingly used as foundation elements, particularly in projects requiring fast construction. Different types of drilled displacement (DD) piles are available in practice. DD piles are classified according to the drilling tool design and installation method. The capacity of a DD pile, depending on its type, is between the capacities of geometrically similar nondisplacement and full-displacement piles installed in the same soil profile. This paper provides an overview of the different types of DD piles and their installation techniques and describes three design methods used in practice. It also compares DD pile capacities obtained with these design methods for two different sites.

Jan 1, 2010

By Charles H. Wells

This paper describes a commercial installation of a sophisticated instrumentation and control system designed to maximize the performance of heavy medium cyclones. Samples of plant feed and its products were collected and analyzed for ash content so that measures of efficiency could be determined for plant operation under (1) manual control and (2) automatic (computer) control. The heavy medium cyclone control strategy and its digital computer implementation are discussed in detail. The sample results are analyzed and the economic benefits of automatic control are discussed. Results from the initial data sets quantify the economic benefits of automatic closed-loop control; viz, increased recovery and reduced clean coal variability have been clearly demonstrated.

Jan 1, 1981

By T. Qiu

"The purpose of this study is to investigate the effect of the dosage of sodium hypochlorite as activator on the flotations of depressed marmatite and depressed chalcopyrite, with a focus on activation-flotation kinetics. Four flotation kinetic models were applied to test data using 1stOpt statistical analysis software to estimate the relationships between the maximum flotation recovery rates for the depressed marmatite and depressed chalcopyrite, the flotation rate constants and the sodium hypochlorite dosages. Within the range investigated, the highest flotation performances of depressed marmatite and depressed chalcopyrite were obtained at 2.5 mL/L sodium hypochlorite with zinc recovery rate of 93.8 percent and 3 mL/L sodium hypochlorite with copper recovery rate of 94.6 percent, respectively, after four minutes of flotation. A second-order model with rectangular distribution of flotabilities gave the best fit to test data collected at various sodium hypochlorite dosages. For the highest flotation performances of depressed marmatite and depressed chalcopyrite, the respective equations of their flotation models were derived and presented.IntroductionCyanidation tailings are the solid residues generated by gold plants that use cyanide to extract gold (Lv, Ding and Qian, 2015; Zhang, Li and Yu, 2013). Because of increasing demand for gold, the Chinese gold industry has developed rapidly, with production amounting to 451.799 tons in 2014, an increase of 5.5 percent from 2013. Chinese gold production has been the highest in the world for eight consecutive years. As a result, more than 2.45 million tons of cyanidation tailings are estimated to be discharged into tailings ponds every year (Li et al., 2010; Lv, Ding and Qian et al., 2015; Wang et al., 2015; Zhang, Li and Yu, 2013; Zhang, Li and Yu, 2012), and approximately 300 million tons of cyanide tailings are stockpiled in China, with the potential to cause serious environmental pollution as well as death to wildlife (Adams and Lloyd, 2008; Donato et al., 2007; Hewitt, Breuer and Jeffery, 2012; Velasquez-Lopez et al., 2011; Stephen et al., 2009; Zagury, Oudjehani and Deschenes, 2004). Concerns over cyanidation tailings are not exclusively environmental but also economic, as tailings occupy considerable land area, and tailings storage facilities increase the production costs of gold enterprises (Donato et al., 2007). Tailings often contain other valuable metals such as zinc, lead and copper. For example, the cyanidation tailings of Gaoyao Hetai Gold Plant in Guangdong Province contain 2.5 percent copper (Cu), 0.31 percent lead (Pb), 0.23 percent zinc (Zn) and 15.36 percent iron (Fe) (Shi, 2008), and the tailings of Tianshui Gold Plant in Gansu Province contain 1.94 percent Cu, 5.96 percent Pb, 0.27 percent Zn and 24.62 percent Fe. Cyanidation tailings have therefore been increasingly viewed as a secondary resource rather than waste."

Jan 1, 2016