International Journal of Nonferrous Metallurgy

Journal Information
ISSN / EISSN : 2168-2054 / 2168-2062
Current Publisher: Scientific Research Publishing, Inc. (10.4236)
Total articles ≅ 56
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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.
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.
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

Abstract:
Bauxite deposits for production of alumina are lacking in Nigeria and there is an aluminium smelter plant in the country which requires alumina for its operation. Development of alternative alumina resource using clays that are abundant in the country is the focus of this paper. The thermal activation of Ibere clay from southeastern Nigeria for optimal leaching of alumina was investigated. The clay assayed 28.52% Al2O3 and 51.6% SiO2, comprising mainly kaolinite mineral and quartz or free silica. The alumina locked up in the clay structure was rendered acid-soluble by thermal activation which transformed the clay from its crystalline nature to an amorphous, anhydrous phase or metakaolinite. The clay samples were heated at calcination temperatures of 500°C, 600°C, 700°C, 800°C, and 900°C at holding times of 30, 60, and 90 minutes. Uncalcined clay samples and samples calcined at 1000°C (holding for 60 minutes) were used in the control experiments. The result of leaching the clay calcines in 1 M hydrochloric acid solution at room temperature, showed that the clay calcines produced at 600°C (holding for 60 minutes) responded most to leaching. Samples calcined for 60 minutes also responded better than those held for 30 or 90 minutes. Based on activation energy studies, it was observed that calcines produced at 600°C (for 60 minutes) had both the highest leaching response (50.27% after 1 hour at leaching temperature of 100°C) and the lowest activation energy of 24.26 kJ/mol. It is concluded therefore that Ibere kaolinite clay should be best calcined for alumina dissolution by heating up to 600°C and holding for 60 minutes at that temperature. The clay deposit has potential for use as alternative resource for alumina production in Nigeria where bauxite is scarce.
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.
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), 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.
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

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.
Fredrick Madaraka Mwema
International Journal of Nonferrous Metallurgy, Volume 6, pp 1-16; doi:10.4236/ijnm.2017.61001

Abstract:
The purpose of this research is to develop a SolidWorks® model for transient temperature field of laser welding of PMMA/SS 304 materials for application in fabrication of the ultrasonic back-plate, with a view of optimizing the experimental conditions. The study is carried out on these materials because of the increasing application of both metals and non-metals. The work focuses specifically on these materials because they have been experimentally studied previously and as such, this study can be accepted as an assessment into feasibility of using SolidWorks® model to study the temperature field of the laser welding processes of metals and non-metals. The results of the SolidWorks® transient thermal model show that there is a concentration of high temperatures at the point of contact. It also shows that temperature decreases as we move in (between laser and the top face) to the thickness of the part. Additionally the maximum temperature occurs at the last point of the welding; this may be due to the accumulation of the temperature before arriving at the end. These findings are comparable to the previous simulated and experimental results on temperature field during laser welding of PMMA/SS 304 materials. However, SolidWorks® is shown to present a challenge in modeling a moving source of laser power.
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.
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