Duplex Process to Produce Ferromanganese and Direct Reduced Iron by Natural Gas

Abstract

The application of natural gas instead of solid carbon to produce ferromanganese is a way forward in sustainable development. Mass and energy balances for an integrated duplex process to produce ferromanganese and direct reduced iron (DRI) by natural gas were studied. The process consists of natural gas injection into molten ferromanganese yielding carbon and hydrogen in which the dissolved carbon into the molten metal bath reduces MnO from a coexisting molten slag that is produced from the smelting of manganese ore. Hydrogen and CO gases reduce solid manganese oxides and iron oxides in the Mn ore to MnO and Fe in the ferromanganese reactor burden. A hot gas with a significant amount of CO and H 2 leaves the reactor and is upgraded to a rich CO−H 2 gas mixture via methane use in a gas reformer. The obtained highly reducing gas is then used to reduce iron ore in a direct reduction reactor for DRI production, while the DRI reactor process gas is partly looped into the gas reformer and the rest is used in an energy recovery unit for electric power generation for the ferromanganese reactor. It is shown that the presented duplex process is more sustainable than the current commercial ferromanganese production process and its application is accompanied by about 50% less electric energy consumption and about 40% less CO 2 emission, excluding the source of electricity.

A Sustainable Process to Produce Manganese and Its Alloys through Hydrogen and Aluminothermic Reduction

“…For instance, the energy consumption is the highest when FeMn is produced via the use of iron oxide in the charge of the PRR, and this is obvious as more hydrogen is needed compared to the other metal products according to Table 2. To evaluate the obtained energy consumption values, theoretical and industrial energy consumptions for HCFeMn production from high grade Mn ores in SAF [3,21] are also given in Figure 13. It is observed that the production of Green FeMn via HAlMan process is advantageous than the current SAF technology considering both theoretical and industrial cases.…”

“…The production of HCFeMn through a carbothermic process in SAF is accompanied with significant CO 2 emission and 1-1.4 tCO 2 /t metal. On the other hand, SAF process is an energy intensive process, and 2000-3000 kWh energy is utilized per ton metal as presented previously [3]. Therefore, the development of new sustainable Mn production processes is important to reduce the greenhouse gases in the future.…”

“…Instead of carbothermic SAF process, the production of Mn and its alloys from Mn ores or secondary Mn sources is possible via a few approaches. It was shown previously that using methane instead of solid carbon via a potential technology is accompanied with less energy consumption and less CO 2 emission, while it is also possible to produce valuable by-products [3]. The idea of using methane was based on the fact that the reduction of Mn oxides (MnO 2 , Mn 2 O 3 , Mn 3 O 4 ) to MnO is possible by CO and H 2 gases, while further MnO reduction to metallic Mn is not possible by these gases and carbon supply from methane is needed to reduce MnO [3,4].…”

“…It was shown previously that using methane instead of solid carbon via a potential technology is accompanied with less energy consumption and less CO 2 emission, while it is also possible to produce valuable by-products [3]. The idea of using methane was based on the fact that the reduction of Mn oxides (MnO 2 , Mn 2 O 3 , Mn 3 O 4 ) to MnO is possible by CO and H 2 gases, while further MnO reduction to metallic Mn is not possible by these gases and carbon supply from methane is needed to reduce MnO [3,4]. It is worth mentioning that in SAF, MnO reduction occurred by C in a coke bed area and the generated CO reduces the higher Mn oxides in the furnace burden to MnO.…”

Selection of an Inert Gas System for the Transportation of Direct Reduced Iron

“…ey concluded that the reduction time should be appropriately extended to reduce surface defects of new iron particles, that the semi-wet ballmill process and DRI are not suitable for processing, and that the ideal one should be selected from other wet ball mills. Safarian [20] applied an integrated duplex process method to examine the mass and energy balances to produce ferromanganese and directly reduced iron (DRI) with natural gas. He concluded that the production of ferromanganese and DRI with natural gas is feasible in terms of process chemistry in a FeMn reactor and causes 40% less CO2 emissions.…”