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By R. E. Mussler

Electrowinning of copper from chloride solutions in a diaphragm cell was studied by the Bureau of Mines. The copper powder product was shaken periodically from the cathode and removed from the bottom of the cell. The effects of copper concentration, brine concentration, copper chloride species, and cell voltage were investigated. Power consumption of 1.1 and 2.1 kW-hr/kg were obtained with cuprous and cupric chloride solutions, respectively.

Jan 1, 1975

By K. N. Hebbar, R. G. Reddy

Spent potliners (SPL) were declared hazardous waste under RCRA (K088) in July, 1990. The glass formation characteristics of the SPL was studied. The SPL glassy matrix were analyzed using X-ray diffraction and optical microscopy. Results showed that SPL can be fixed in a glassy matrix with the addition of sand and limestone. The optimum amounts of additives were determined for obtaining the best glass formation characteristics.

Jan 1, 1995

By AIME AIME

AN outstanding session of the Annual February Meeting was one held under the joint auspices of several groups on Tuesday afternoon, Feb. 22, as a symposium on the question of preserving peace in the postwar era through the control of the supply of sundry minerals vital to the Axis nations. D. H. McLaughlin and R. C. Allen were associate chairmen. And C.K. Leith led the discussion.

Jan 1, 1944

By S. Bhattacharjee, S. K. Singh, R. K. Galgali

A method for the preparation of zirconia- toughened mullite using dc plasma is presented. An indigenously developed 50-kW thermal plasma reactor is used for the preparation of zirconia-toughened mullite using a dissociated zircon and alumina mixture. Both XRD and SEM studies of the product confirmed the formation of mullite and zirconia. The zirconia grew as equiaxed grains of uniform size (~5 µm) in a mullite matrix.

Jan 1, 2002

By David J. Reddish, Barry N. Whittaker

The characteristics of surface ground strains due to longwall mining are reviewed with special reference to U.K. coal mining observations. The current empirical method of estimating ground strain is discussed. A method of determining surface ground strain above a longwall extraction is described whereby strain can be accurately represented along a line in any direction. The discussion is supported with examples of its application to common subsidence engineering problems.

Jan 1, 1984

Alfred Noble Joint Prize Committee F B Foley, '56 American Documentation Institute F B Foley, '56 American Geological Institute J L Gillson, Nov '56, H A Meyerhoff, Nov '57 Committee on Government Relations J L Gillson, '56 American Power Conference Paul R Nichols, '56 American Standards Association Mining Standards Board E R Borcherdt, Jan '58, Otto Herres, Jan '58 Alternates E W Bullard, Dec '56, and J K Richardson, Dec '56

Jan 1, 1956

Activity-composition-temperature relations for both gold and nickel have been determined for the solid and liquid states of the gold-nickel system by the application of the Margules equations. These relations are in satisfactory agreement with activity measurements of nickel in the solid state, the observed phase boundaries of the system between 700 and 1725°K, as well as being consistent with data on the enthalpy of mixing.

Jan 1, 1971

By P. D. Zemany, G. W. Sear, B. W. Roberts

Vanadium metal is embrittled by hydrogen at a temperature as low as 250°C when held in the presence of manganese metal and water vapor in a rough vacuum. It is established that the property changes are caused by the catalytic decomposition of water vapor at the vanadium surface and the diffusion into and solution in the vanadium of the resultant hydrogen. It is found that manganese is a necessary component of the catalyst. The manganese is transported in the vapor phase by an unknown molecule. A deuterium tracer experiment demonstates the role of water vapor in the embrittle-ment process. VANADIUM metal foils were observed to become embrittled' at a temperature of about 300 °C when held in the presence of manganese metal and a small amount of moist air, This paper describes the investigation to find the embrittling agent and an understanding of the relatively low temperature reactions that are involved. Experimental The vanadium metal foil used was prepared by cold-rolling and pack-rolling 32 mil sheet" in a series of steps down to 1 mil foil. The original observation was confirmed by sealing vanadium foils of 3 x 10 sq cm into individual Pyrex tubes with manganese powder† and a con- trol tube containing only the vanadium foil. These tubes were evacuated to 10 -5 mm Hg without baking and sealed. After heat treatment for 200 hr at 300°C, the control foil showed no change in duetility, whereas the foil contained in the manganese— containing tube was embrittled. The visual appearance of each was unchanged. A series of Pyrex sample tubes, about 2.5 cm diam and 25 cm long, were prepared, each containing a 3 x 10 sq cm piece of foil and 5 g manganese powder at the lower end of the tube. By reducing the time of anneal and the temperature of these samples, it was found that embrittlement could be created at 250°C in a time as short as 1 hr. Since the vanadium metal used here has been drastically cold-worked by rolling, it is assumed that it contains a maximum number of dislocations. To check the possible necessity of dislocations in this low temperature reaction, a vanadium foil sample was annealed in Vycor for 2 hr at 800°C to re crystallize and reduce the dislocation concentration. Metallographic examination showed grains which were not visible before annealing. The embrittlement procedure was carried out at 300°C and 3 hr. Upon checking the foil no embrittlement was observed. Further experiments demonstrated that about 6 hr at 300°C are required to create embrittlement in the foil. This delay in the onset of embrittlement in the vanadium foil suggests but does not prove that dislocation channels play a role in the embrittlement phenomena. If manganese metal is necessary for this low temperature embrittlement, do other elements in the transition metals group yield the same result? To check this qualitatively, a group of elements of similar atomic radii were obtained and sealed as before into Pyrex tubes with a sheet of vanadium foil. These tubes were annealed at 250°C for 6 hr and included (with radii)-2 A1 (1.4A), As (1.25A), Be (1.2A), Co (1.25A), Cr (1.45A), Cu (1.25A), Fe (1.25A), Ga (1.2A), Ge (1.25L%), Mn (1.3A), Ni (1.25A), Si (1.2A), Ti (1.45A), Zn (1.3A), air, H,O, 10 cm Hg of dry hydrogen, and MnO, powder. Upon testing the above sample foils for brittleness, only the manganese-containing tube yielded a brittle foil. Manganese Transport—To eliminate contact of manganese metal powder and vanadium foil, sample tubes were prepared with fritted glass barriers. The embrittlement reaction was still found to occur. Thus, the mode of transfer of manganese is certainly vapor transport. A vanadium foil was embrittled by this mechanism in an evacuated Pyrex tube for 8 hr at 300°C. By means of X-ray fluorescence analysis,' the amount of manganese added to the surface was established at 5 ±2 x 10 -6 g per sq cm. Since the average rate of manganese deposition is known, an effective average pressure of an assumed carrier compound can be computed. ___ P = M/T v2p mkT

Jan 1, 1959

The First Conference of the Powder Metallurgy Committee convened in the East Foyer of the Hotel Waldorf-Astoria, New York City, at 9:45 a.m., on Feb. 21, 1944, Mr. John Wulff, General Chairman, presiding. THE CHAIRMAN.-In behalf of the American Institute of Mining and Metallurgical Engineers I welcome all members and guests to this conference on Powder Metallurgy. We hope that this meeting will give expert and novice in the field a chance for discussion. Unfortunately, the subject has been overemphasized by some, and, of late, severely criticized by others. We have here today powder producers, fabricators, and engineers of different viewpoints, who can make the meeting a success. Such success depends not only on the caliber of the papers presented but more so on the discussion. To give you time for a free exchange of views, the papers have been shortened purposely. With the hope that you will all benefit by this conference, I shall turn the meeting over to the Chairmen of the morning session, Mr. Roland P. Koehring, of Moraine Products Division of General Motors, and Dr. R. K. Waring, of the New Jersey Zinc Company. SESSION ON DESIGN FACTORS IN POWDER METALLURGY R. P. Koehring and R. K. Waring presiding The opening paper of the session was presented by Mr. Fred P. Peters, as follows:

Jan 1, 1945

By George P. Demopoulos

n this study we have sought to highlight the critical linkage between individual reaction kinetic parameters (usually determined in small bench scale experiments) and large continuous reactor performance by focusing on the industrially significant zinc pressure leach process. To this end a comprehensive mathematical model previously developed for the description of this process was employed. In this paper we have examined in particular how small variations in key kinetic parameters impact on the autoclave&apos;s performance, i.e. attainment of autogenous steady-state temperature, zinc conversion and solution chemistry. The reaction parameters studied were: (i) stoichiometry of the marmatite leaching reaction; (ii) the activation energy of the same reaction, E,; (iii) the rate constant of the ferrous to ferric oxidation reaction, k,; and (iv) the apparent equilibrium constant for ferric precipitation, K,. This parameter sensitivity analysis was done under no oxygen mass transfer control limitations. Model predictions were found to be more sensitive to the kinetic parameters under certain conditions than others. The most dramatic finding was the one related to the small amount of sulfate produced during marmatite leaching. In connection to this it was found that the small percentage (< 5 %) of sulfate produced enhances the autothermal operational stability of the autoclave. The need for accurate kinetic parameter determination under conditions similar to those encountered in industrial zinc pressure leaching was demonstrated.

Jan 1, 1999

By Duclerc Fernandes Parra, Vijaya Kumar Rangari, Washington Luiz Oliani, Ademar Benevolo Lugao, Nilton Lincopan

Due to its versatility and low cost, polypropylene (PP) is one of the most widely used polymers in the world, consequently in research and development of new products. The polypropylene modified was prepared by gamma irradiation in acetylene at 12.5 kGy dose, technical polymer also known as high-melt-strength-polypropylene (HMSPP). It was mixed with montmorillonite (MMT) clay and silver nanoparticles (AgNPs) for bactericide activity. HMS-Polypropylene-clay-silver nanocomposites were manufactured using twin-screw extruders. Those materials were prepared by a melt mixing process via twin screw extrusion with a wide range of processing conditions. The polypropylene nanocomposites (PPNC) surfaces were exposed to gamma-radiation (60Co) source in presence of nitrogen as inert atmosphere at 1; 3; 5; 10; 20 and 50 kGy doses for modified the surfaces in order to enhance biocide activity. The samples surfaces were characterized by Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDX) and evaluated by determination of bactericide effects. The results indicate the formation of structures predominantly intercalated of HMSPP nanocomposite. Contact tests for antibacterial activity of the hybrid polymer were applied against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria. The irradiations on the samples surfaces were insufficient to promote activity on contact biocide tests.

Mar 1, 2018

By Toshiyuki Nohira, Tetsuo Oishi, Hideki Ono, Hirokazu Konishi

The electrochemical formation of Tb-Ni alloys was investigated in a molten LiCl–KCl–TbCl3 (0.50 mol% added) at 723 K. Open-circuit potentiometry was conducted using a Ni electrode after electrodepositing Tb metal at 0.20 V (vs. Li+/Li) for 300 s. There were four potential plateaus at (a) 0.66 V, (b) 0.80 V, (c) 0.95 V and (d) 1.56 V, respectively. Alloy samples were prepared by potentiostatic electrolysis at 0.60 and 0.70 V at 723 K. The alloy phase was identified as only TbNi2. Anodic dissolution of Tb from the formed TbNi2 was conducted at 0.90, 1.20 and 1.60 V, respectively. In the sample obtained at 0.90 V for 3 h, the existence of TbNi3 was identified by the XRD. Phase of the sample obtained at 1.20 V for 3 h was TbNi5. The sample obtained at 1.60 V for 3 h was Ni. Alloy samples were prepared by potentiostatic electrolysis at 0.50–0.80 V for 1 h using Ni plate cathodes in a molten LiCl–KCl containing TbCl3 (0.50 mol%) and NdCl3 (0.50 mol%). The highest mass ratio of Tb/Nd in the alloy sample was 56 at 0.70 V.

Mar 1, 2018

By Isa Nozari, Asghar Azizi

The extraction of copper from sulfate leaching liquor was investigated using Acorga M5640 commercial extractant in kerosene diluent. The effects of important factors such as the extractant concentration, contact time, liquor pH, and temperature were examined on the separation factor Cu/Fe and the extraction efficiency of copper. The results indicated that nearly 92.32% copper was extracted from the leach liquor at 10% (v/v) Acorga M5640 concentration, 1:1 aqueous/organic phase ratio, 20 min contact time, pH 2.5, and 25 °C temperature. Also, the further increase in the values determined had no positive impact on the extraction of copper. Under these conditions, the separation factor Cu/Fe was obtained about 29.64. The extraction mechanism was studied applying the plot of log(D) – 2 pH against log [extractant] and it proved the association of two moles of Acorga M5640 for the extraction of one mole of copper. McCabe–Thiele diagram was constructed and a single-step extraction process was found to obtain themaximumextraction. Additionally, thermodynamic datawere investigated and the extraction process was endothermic and non-spontaneous at 298 K (ΔH = 27.05 and ΔG = 15.52 kJ mol−1). Moreover, the loaded organic phase was stripped and 80.94% copper was recovered after 20 min using 10% sulfuric acid concentration.

Jul 31, 2020

By Eugie Kabwe

Rock bolts are components of tunnel support structures and their efficacy in reinforcement requires the appropriate estimation of the bolt pre-tension. However, cases of ineffective rock bolt application due to loosening are common which leads to the potential failure of the support structures, thus negatively affecting the tunnel stability. The effective employment of pre-tensioned bolt within support structures requires an appropriate installation tension as a result of sufficient bolt head/nut pre-load. Henceforth, this paper presents a load indicator washer (LIW) capable of withstanding assigned static loading as well as provides an appropriate pre-tension. The different LIW breadths are numerically analysed in the finite element code (ABAQUS) to estimate deformation when a designated 60-kN pre-load is applied. The numerical simulation employs a bi-linear isotropic hardening constitutive law governed by the von Mises yield criterion. The simulation also considers the nominal temperature of the nutLIW-rock bolt connection. Therefore, a long-term relaxation effect on bolt pre-tension as a result of stress relaxation is neglected. The compressive force required to achieve the LIW-predetermined deformation is the bolt pre-tension. It is drawn from the simulation results that the 1.5-, 2.0-, 3.0-, 3.5-, and 4.0-mm-thick LIWs are completely flattened when subjected to 28-, 42.5-, 65-, 76-, and 88-kN pre-load respectively.

By Zhang Jianliang, Xu, Zuo, Runsheng, Haibin, Kexin, Jiao

Full oxygen blast furnace iron-making is one of the new technologies, which is most likely to realize large-scale application. In this paper, based on the technology of full oxygen blast furnace, the reduction behavior of pellets is studied systematically by using the analytic method of non-isothermal dynamics on the different atmosphere(CO,H2) and the dynamics model of gas-solid reduction reaction is constructed, which lay the foundation of reduction model establishment of full oxygen blast furnace burden. The result shows that the time of pellets which began to react is delayed with the increase of the content of H2. When the temperature is between 650 'C and 1050 'C, the content of H2 in the reduction atmosphere is larger, and the rate of the reduction pellets is larger. The reduction rate changes at 780 'C, and a certain amount of H2 in the reducing atmosphere will significantly improve the reduction reaction when the temperature is above 780 'C. Non-isothermal reduction behavior is controlled by interfacial chemical reaction and internal diffusion under high reduction potential. H2 ratio in reducing atmosphere increased from 0% to 100%. The reduction reaction of the apparent activation energy decreased from 49.03kJ-mor1 to 33.74kJ·mor1.

Jan 1, 2013

By J. Yao

Synthetic indium-bearing zinc ferrite (IBZF) was mechanically activated by a tumbling mill. Subsequently, the behavior and kinetics of leaching zinc and indium from the initial IBZF and activated IBZF in sulfuric acid solution were investigated. The results demonstrate that the tumbling ball milling enhances the leaching reactivity of IBZF and increases the zinc and indium extractions. The reaction temperature and H2SO4 concentration have an important effect on leaching zinc and indium from the initial IBZF and activated IBZF. The kinetic model -ln(1-x) = kt was used to describe the kinetics of leaching zinc and indium from the initial IBZF and activated IBZF and to calculate the kinetic parameters. The tumbling ball milling causes a decrease in activation energy and reaction order, which indicates that the dissolution of IBZF after mechanical activation by a tumbling mill becomes less sensitive to temperature and H2SO4 concentration. For the zinc leaching, the activation energy decreases from 73.9 to 70.3 kJ/mol and the reaction order decreases from 0.72 to 0.70. For indium leaching, the activation energy decreases from 78.1 to 73.5 kJ/mol and the reaction order decreases from 0.82 to 0.69. It is found that the dissolution rates of the initial IBZF and activated IBZF are controlled by surface chemical reactions.

By SANDEEP KUMAR JENA

This paper reviews the recovery of potassium from different rocks and mineral sources. Global demand for potassium is rising steadily due to the growth of agricultural production. Fertilizer manufacture consumes the majority of the world’s potassium production, with other uses including those in the pharmaceutical, glass, ceramic, food and detergent industries. The availability of soluble potash (K2O) minerals, such as sylvite, kainite and carnalite, in countries like Canada, the United States, Israel and Russia makes them major potash producers, whereas agriculture-based countries like Liberia, Somalia, Central African Republic, Thailand, Indonesia, Malaysia and India meet their potassium requirements through imports only. In these countries, the huge availability of potassium-bearing rocks/minerals like nepheline syenite, feldspar, mica and glauconitic sandstone, containing around 4 to 17 percent K2O, brings up the prospect of commercial production of potassium. Potassium recovery from minerals/rocks is complicated due to the uniform distribution of potassium throughout the crystal structure. Different physico-chemical separation methods like bioleaching, chemical leaching, flotation and roast-leaching have been discussed for the successful recovery of potash values from these rocks/minerals. Although seawater is vastly available, the recovery of potassium from seawater using chemical precipitation, solvent extraction, membrane separation and ion-exchange methods is not cost-effective due to low concentration of potassium.

By R. Padilla

In most of the Chilean copper and gold concentrates, arsenic is present mainly as enargite, Cu3AsS4, which at the conventional roasting or smelting temperatures decomposes liberating arsenic as gaseous compounds. The objective of this investigation was to study the decomposition reaction of enargite in an inert atmosphere in the range of 500 °C - 750°C. The results obtained indicated that the decomposition begins at about 525 °C. Two distinct regions in the temperature dependence of the decomposition rate were observed: a low temperature region between 525 °C to 650°C and a high temperature region between 650 °C to 725 °C. The X-ray diffraction analysis suggests that the decomposition of enargite occurs through the formation of intermediate tenantite, according to the following sequential reactions: 4Cu3AsS4(s) ? Cu12 As4S13(s)+ 3/2S2(g) Cu12 AS4S13(s) ? 6Cu2S(s) + 2As2S3(g) + 1/2S2(g) The decomposition kinetics was analyzed by using the model for a topochemical reaction of spherical particles: 1-(1-X) 1/3 = kt, which represented well the data. Apparent activation energies of 113 kJ/mol and 60.5 kJ/mol were found for the low and high temperature regions, respectively.

Jan 1, 1999

By Hart A. T, Lanigan P. G

BHP is currently undertaking research into plasma are metallurgical processing at the Central Research Laboratories (CRL), Shortland. The use of high intensity plasma arcs for melting and smelting has a number of advantages, including; the ability to control atmosphere and furnace operating conditions, total enclosure, high temperatures, versatility, and low in-process inventory in a compact system. The intensive conditions, achievable in a plasma furnace system, make it particularly useful for the smelting and melting of difficult-to-treat materials, such as ore and metallic fines and refractory ores. Two transferred arc plasma smelting furnaces have been set up at CRL; a 100kg furnace is used for small scale melting and smelting studies and a 1 tonne furnace for pilot scale plasma processing studies and equipment development. Power is supplied by a 1MW GEC thyristor DC power supply. A 220kW DC power supply is available for "off site" pilot process trials and demonstrations, and a 150kW non-transfered are plasma torch is also available for other studies. The facility has been designed to allow maximum flexibility in researching and developing applications in metallurgical processing and transferring developed technology to company operations. The objectives behind the development of the facility, details of the facility and an outline of current research areas will be Discussed.

Jan 1, 1987

By Seth C. Schaefer

The Bureau of Mines investigated thermodynamic properties of Mn304 (manganomanganic oxide) and Mn203 (manganese sesquioxide). The standard Gibbs energies of formation (?Gf°) of Mn304 and Mn203 from their lower oxides were determined with high-temperature galvanic cells using stabilized Zr02 (zirconia) as the electrolyte. Potential measurements were obtained for the cell Pt, MnO, Mn304//Zr0 2//02(g, 0.0112 atm), Pt, with the overall cell reaction 6Mn0(c) + 02(g, 0.0112 atm) = 2Mn304(c), where- 02 refers to indicated partial pressure of oxygen at the reference electrode. Similar measurements were obtained for the cell Pt, Mn304, Mn203//ZrO2//02(g, 0.0115 atm), Pt, with the overall cell reaction 4Mn304(c) + 02(g, 0.0115 atm) = 6Mn203(c). Equilibrium oxygen pressures for the Mn0-Mn304-02 and Mn304-Mn203-02 systems were measured and may be expressed for the respective systems as [23,400 109 P02 T + 11.91 (764.9 - 1,208.6 K) and log p02 = - 11,957 + 9.66 T (968.6 - 1,208.2 K),] where pressure (p02) is in atmospheres and temperature (T) is in kelvins. Standard thermodynamic properties of Mn304 and Mn203 were derived from these measurements and auxiliary thermodynamic data from the literature.

Jan 1, 1982