Thermodynamic Behavior of Manganese Oxide in Lime-based Manganese Smelting Slags

Abstract

The thermodynamic behavior of MnO in the CaO-SiO 2 -MnO slag system of lower basicity to understand the smelting reduction of silicomanganese was investigated. Experimental results indicated that the activity coefficient of MnO was not affected by MnO content less than 30 mol%. However, it did in fact increase as the MnO content increased beyond 30 mol% because the activity coefficient of MnO is closely associated with the silicate structure. The activity coefficient of MnO also increased with increasing basicity of slag and MgO content because of the free O 2 − ions that are provided into the slag. On the other hand, the effect of the Al 2 O 3 content on the activity coefficient of MnO was analyzed that the structure in the CaO-SiO 2 -MnO-Al 2 O 3 system changes from that of a Si-O-Si linkage to that of Si-O-Al and Al-O-Al linkages as the content of Al 2 O 3 increases. Structural considerations concerning the effect of slag composition on the activity coefficient of MnO are discussed in detail using Fourier transform infrared (FT-IR) spectroscopy. Finally, it is shown that manganese recovery can be increased by increasing the activity coefficient of MnO in the slag.

Behavior of Battery Metals Lithium, Cobalt, Manganese and Lanthanum in Black Copper Smelting

“…When comparing to earlier literature data [22,26,27], the calculated values of manganese distribution coefficient between copper alloy and slag appear to be much lower in this study. Jung et al [26] studied the manganese distribution between Cu alloy and CaO-SiO 2 -Al 2 O 3 (13%)-MnO(5%)-MgO(17%) slag at 1500 • C and at oxygen partial pressure 2.71 × 10 −12 atm.…”

“…The thermodynamic behavior of MnO in the CaO-SiO 2 -MnO slags at 1500 • C and oxygen partial pressure of 2.75 × 10 −10 atm was studied by Eom et al [27]. Experimental results showed that manganese recovery can be increased by increasing the activity coefficient of MnO in the slag.…”

“…Jung et al [26] studied the manganese distribution between Cu alloy and CaO-SiO 2 -Al 2 O 3 (13%)-MnO(5%)-MgO(17%) slag at 1500 • C and at oxygen partial pressure 2.71 × 10 −12 atm. Eom et al [27] investigated the manganese distribution between copper alloy and CaO-SiO 2 -Al 2 O 3 (14.7%)-MnO(7.5%) slag at 1500 • C and at oxygen partial pressure 2.75 × 10 −10 atm. The distribution coefficients obtained in these studies have been plotted in Figure 7 for comparison.…”

“…The distribution coefficient of manganese between copper alloy and slag as a function of oxygen partial pressure. Results from three earlier studies[22,26,27] have been plotted for comparison.…”

Thermodynamic Activity of MnO in CaO–SiO₂–MnO–FeO–MgO Molten Slags

“…Many researchers have studied the thermodynamic properties of MnO in the slag containing MnO. The slag systems studied covered MnO-SiO 2 , 2) MnO-SiO 2 -CaO, 3,4) MnO-CaO-Al 2 O 3 , 3,5) 10) sulphurization of steelmaking slag 11) ), and the slag system containing Cr 2 O 3 for stainless steel refining process. 12) Eom et al 4) studied the thermodynamic behavior of MnO in the CaO-SiO 2 -MnO system, CaO-SiO 2 -MnO-Al 2 O 3 system and CaO-SiO 2 -MnO-MgO system slags without FeO in the reducing process of MnO during the smelting process of high manganese TWIP Steel.…”