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1

High-temperature carbothermal dephosphorization of Malaysian monazite

Udayakumar Sanjith, Sheikh Abdul Hamid Sheikh Abdul Rezan, Baharun Norlia, Pownceby Mark

Physicochemical Problems of Mineral Processing

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2021

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Vol. 57, iss. 6

140--155

EN

High-temperature carbothermal reduction experiments with graphite powder were conducted to assess the dephosphorization behavior of Malaysian monazite concentrate. Thermodynamic analysis of the possible dephosphorization reactions was conducted to evaluate the feasibility of the carbothermal reduction of the monazite phases. The effects of temperature, particle size, and monazite to carbon ratio were then investigated under different conditions. The carbothermal reduction experiments were conducted based on the Taguchi design method, and up to 97% of phosphorous removal was achieved under optimized conditions. The optimal conditions for dephosphorization were determined as; a reduction temperature of 1350 °C, a particle size of -75 μm, and monazite to carbon molar ratio of 0.3. Microstructural and phase characterization of the dephosphorized products revealed that CeO2, Nd2O3, La2O3, and Pr2O3 oxide phases were prominent, and no residual peaks of monazite remained in the reduced products. The information gained from the study can aid in the design of a suitable post-dephosphorization hydrometallurgical treatment for exploiting Malaysian monazite as a local source of REEs.

2

The Effect of Slag on the Effectiveness of Phosphorus Removal from Ferrous Alloys Containing Carbon, Chromium and Nickel

Kawecka-Cebula E., Karbowniczek M., Suliga I.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 1

301--306

EN

The aim of this study was to determine the impact of slag composition on phosphorus removal from ferrous solutions containing carbon, chromium and nickel. Additions of cryolite, Na3AlF6, were applied for better fluxing and higher phosphate capacity of the slag. An X-ray analysis of final slags formed during dephosphorization of ferrous solutions containing chromium and nickel with CaO-CaF2 or CaO-CaF2-Na3AlF6 mixtures of different chemical compositions was carried out. The equilibrium composition of the liquid and the solid phase while cooling the slags from 1673K to 298K was computed using FactSage 6.2 software. The performed equilibrium computations indicated that the slags were not entirely liquid at those temperatures. The addition of cryolite causes a substantial increase of the liquid phase of the slag. It also has a favourable effect on the dephosphorization grade of hot metal. The obtained results were statistically processed and presented in the form of regression equations.

3

Optical basicity of manganese and iron oxides

Kawecka-Cebula E.

Metallurgy and Foundry Engineering

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2001

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Vol. 27, no. 1

15-29

EN

There exists in the literature a few sets of the optical basicities of the oxides of such transition metals like iron and manganese which seems incorrect or even impossible. This study is aimed at some unification of the computations of the optical basicities' for the slags containing the oxides of those two elements. Having access to such experimental data like: sulphide capacity Cs, phosphor capacity Cp, sulphur partition index Ls and phosphor partition index Lr as well as the relevant dependences for the oxides' activities, it was attempted in this study to apply the chemical activities of CaO, MnO, FeO, SiO2, and Al2O3, for determination of the optical basicities of some slags. The computations were carried out for the two sets of the optical basicities data for the iron and manganese oxides. Those data were used by the author for the desulphurization and dephosphorization processes simultaneously. It is opposite to the previous attempts which have been made by the other authors who considered those two processes seperatedly. None of the used sets produced satisfactory results, yet the proposed consideration of the chemical activity data seems to be promising and supports the author's concept.

PL

W literaturze istnieje kilka zestawów wartości zasadowości optycznych tlenków metali przejściowych, żelaza i manganu, co wydaje się być nieprawidłowe i wręcz niemożliwe. Praca jest więc próbą ujednolicenia obliczeń zasadowości optycznej żużli zawierających te tlenki. Dla dostępnych danych doświadczalnych: pojemności siarczkowej Cs, pojemności fosforowej Cr, wskaźnika podziału siarki Ls i wskaźnika podziału fosforu, Lr oraz zależności analitycznych dla aktywności tlenków, przetestowano koncepcję wykorzystania aktywności termodynamicznej tlenków CaO, MnO, FeO, SiO2, oraz Al2O3 do obliczania zasadowości optycznej żużli. Obliczenia przeprowadzono dla dwóch zestawów wartości zasadowości optycznej tlenków żelaza i manganu, stosowanych przy odsiarczaniu i odfosforowaniu, wykorzystując je tym razem do obydwu procesów równocześnie. Dla żadnego z testowanych zestawów wartości zasadowości nie uzyskano zadawalających wyników, jednak kierunek zmian niektórych nieprawidłowych przebiegów, po uwzględnieniu aktywności, wydaje się wskazywać na słuszność wybranej koncepcji.