International Journal of Nonferrous Metallurgy

Journal Information
ISSN / EISSN : 21682054 / 21682062
Current Publisher: Scientific Research Publishing, Inc. (10.4236)
Total articles ≅ 56
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Latest articles in this journal

Udochukwu Mark, Charles Nwachukwu Anyakwo, Okechukwu Onyebuchi Onyemaobi, Chijioke Samson Nwobodo
International Journal of Nonferrous Metallurgy, Volume 8, pp 9-24; doi:10.4236/ijnm.2019.82002

Cristian Vargas, Patricio Navarro, Daniel Espinoza, Jorge Manríquez, Erica Mejía
International Journal of Nonferrous Metallurgy, Volume 8, pp 1-8; doi:10.4236/ijnm.2019.81001

Abstract:
In this work the dissolutive behavior of gold in alkaline medium using thiourea (TU), under different variables, was studied in a theoretical and experimental way, in order to determine the conditions under which it is feasible to dissolve gold in thiourea-alkaline medium. A thermodynamic study was conducted by chemical speciation using the method of Rojas-Hernández, together with an electrochemical study where the electric potential was swept in the anodic direction. The main results of the thermodynamic study were that formamidine disulfide (FDS) and sulfinic compounds (S.C.) prevail at alkaline pH; by increasing the initial concentration of thiourea at alkaline pH, the presence of the gold complex is almost zero for any initial concentration of thiourea. By including sodium sulfite in the gold-thiourea system, it was possible to obtain the Au(I)-TU complex at alkaline pH, with a presence of 95.13%. Electrochemical tests allowed verifying that in the absence of sodium sulfite the dissolution of gold in an alkaline medium is very slow but adding sodium sulfite improvements become evident in the dissolution of the metal. Therefore, sodium sulfite catalyzes the gold dissolution process and stabilizes the thiourea. With this study it was possible to establish the feasibility of using thiourea in an alkaline medium for the dissolution of gold, and the conditions under which it is possible to dissolve the gold in that medium. With these fundamentals and conditions, it is now possible to move forward to test this system for minerals and/or concentrates containing gold.
Ogundeji Frncis Oladapo, Alabi Oladunni
International Journal of Nonferrous Metallurgy, Volume 8, pp 25-33; doi:10.4236/ijnm.2019.83003

Abstract:
Each type of a manganese deposit is a problem by itself in the matter of selection of a proper method of concentration, depending on the manganese minerals and their gangue constituents. Hence, this work studied the effect of sodium oleate concentration variation on the froth flotation of manganese ore obtained from Madaka, Niger State, Nigeria. The chemical analysis of the ore shows that it contains 48.4% MnO (37.5% Mn). Peaks were identified in XRD analysis of the crude sample as that of magnosite (MnO), hausmannite (Mn3O4), spessartine and vemuculite (Mg, Fe2+, Fe3+)3[(AlSiO4)O10](OH)2·4H2O. The ore was beneficiated by froth flotation using sodium oleate as collector at varied concentrations of 3 g/kg, 7 g/kg and 10 g/kg. Other chemical reagents used were sodium silicate, fuel oil and calcium hydroxide as dispersant, frother and pH modifier respectively. Results obtained showed percentage metal recoveries of 9.29%, 14.30% and 19.61%, assaying 65.20%, 62.03% and 61.30% Mn respectively. This indicates that at sodium oleate concentration of 3 g/kg, high grade-concentrate can be obtained.
Neeraj Kumar, Kautily Rao Tiwari, Km. Meenu, Arti Sharma, Adya Jain, Shikha Singh, Radha Tomar
International Journal of Nonferrous Metallurgy, Volume 8, pp 35-71; doi:10.4236/ijnm.2019.84004

Abstract:
In this review, we summaries the past few year work on the chemistry of CWA’s and their simulants on various heterogeneous surfaces of zeolites, composites of zeolites and doped zeolite with transition metal oxides. This review elaborates an updated literature overview on the degradation of CWA’s and its simulants. The data written in this review were collected from the peer-reviewed national and international literature.
Zhi-Xiong Liu, Lin Sun, Liang-Dong Tang, Jie Hu, Yang Xiao, Yi-Guang Chen, Zhou-Lan Yin
International Journal of Nonferrous Metallurgy, Volume 7, pp 9-23; doi:10.4236/ijnm.2018.72002

Mohammad Hasan Omidi, Omid Salmani Nuri, Hassan Tavakoli
International Journal of Nonferrous Metallurgy, Volume 7, pp 25-38; doi:10.4236/ijnm.2018.73003

Hidekazu Sueyoshi1), Kousaku Yamada, Masashi Miyazaki, Takuya Okada, Nobuyuki Ashie, Yoshiharu Kousaka
International Journal of Nonferrous Metallurgy, Volume 7, pp 1-7; doi:10.4236/ijnm.2018.71001

Abstract:
The Mechanism of Pb removal from brass scrap by compound separation using Ca and NaF addition was investigated. Because large Ca-Pb compound particles formed by Ca addition rise to the surface of the molten brass, they can be skimmed off from the molten brass. However, fine Ca-Pb compound particles remain in the molten brass because of low buoyancy. By subsequent NaF addition, the reaction between Ca-Pb compound and NaF takes place at their contact regions, resulting in the formation of solid CaF2, liquid Pb and Na gas. Pb is mainly present at the Ca-Pb compound-CaF2 interface. CaF2 acts as a binder for aggregation of fine Ca-Pb compound particles, resulting in the formation of light and large composite compounds, which rise to the surface of the molten brass. A high Pb removal rate is achieved by skimming off.
Hidekazu Sueyoshi1), Masashi Miyazaki, Takuya Okada, Nobuyuki Ashie, Yoshiharu Kousaka
International Journal of Nonferrous Metallurgy, Volume 7, pp 39-55; doi:10.4236/ijnm.2018.74004

Abstract:
2 wt% Ca was added to molten brass containing 3.2 wt% Pb. The composition and grain size of the formed Ca-Pb compound were examined in detail using SEM-EDS and XRD. This revealed that the composition of the Ca-Pb compound depends on the grain size of the liquid phase Pb and the diffusion phenomenon of the Ca in the Ca-Pb compound formed on the surface of the Pb. When the Pb has a fine grain, a compound composed only of Ca-Pb compounds is formed. When the grain size of the Pb is several μm, Ca-Pb compounds containing unreacted Pb in the center are formed. These compounds aggregate into a larger compound grain. From the evaluation of the floating force (the resultant force of the weight and buoyancy of the Ca-Pb compounds formed) and the rising terminal velocity of the Ca-Pb compound within the molten brass, it was found that the floating force and rising terminal velocity depend on the composition and grain size of the Ca-Pb compound. It was found that since Ca-Pb compounds with a floating force greater than 10−6 g∙cm/s2 have a very large rising terminal velocity, they reach the surface of the molten brass in a short time after compound formation and then continue to float on the surface of the molten brass. Thus they can be removed by skimming. The effects of the grain size of the Ca-Pb compound on the floating force and the rising terminal velocity were greater than those of the composition of the Ca-Pb compound.
Abduali Baeshov, Begzat Myrzabekov, Arman Makhanbetov, B. Mishra, Omirserik Baigenzhenov, Vladimir Luganov
International Journal of Nonferrous Metallurgy, Volume 6, pp 17-26; doi:10.4236/ijnm.2017.62002

Abstract:
Method and mechanism for the formation of sulfur compounds during the process of sulfur electrochemical dissolution has been studied, including a technique for the production of composite sulfur-graphite electrode. Along with these, a 3D design is presented in the unit that was used to perform electrolytic reduction, using composite sulfur-graphite electrode. For the first time, a study was carried out for the simultaneous reactions of electroreduction and electrooxidation of sulfur at the sulfur-graphite electrode in sulfurous environment in the same electrolytic bath, with separate electrode spaces. Influences of current density, acid concentration and electrolyte temperature were studied, and it was demonstrated that sulfur is reduced in cathode chamber with formation of hydrogen sulfide gas, and is oxidized in the anode chamber with formation of sulfite and sulfate ions. It has been shown that the methods we propose can be used to produce important sulfur compounds through electrochemical dissolution of specially designed sulfur-graphite electrode.
Hanno Vogel, Bernd Friedrich
International Journal of Nonferrous Metallurgy, Volume 6, pp 27-46; doi:10.4236/ijnm.2017.63003

Abstract:
The neodymium electrolysis produces unnecessary high emission of CF4 and C2F6. These perfluorocarbons (PFCs) are potent greenhouse gases and are not filtered or destroyed in the off-gas. A process control in analogy to the aluminum electrolysis can reduce the PFC emission to a great extend and keep the process in a green process window. Therefore, a theoretical analysis is done of the cell voltage of the industrial neodymium electrolysis in dependence on the neodymium oxide concentration in the electrolyte. The analysis shows the different contributions to the cell voltage focusing on the impact of the anodic overvoltage on the cell voltage, by which the electrolysis process can be controlled. The model of the cell voltage is evaluated by laboratory neodymium electrolysis with a similar setup as the industrial cell. The relation of the oxide concentration, the anodic current density and the cell voltage with the cell resistance are measured. The continuous off-gas measurements show the gas concentration and PFC emissions. The effect of Nd2O3 feeding on the galvanostatic electrolysis is analyzed as well. Based on the results a process control strategy is proposed similar to the aluminum electrolysis strategy. The green process window is in a narrow oxide concentration range, making a continuous and precise oxide feeding essential.
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