What is it about?
The possibility of selective solid-phase reduction of iron from oolitic ore has been experimentally confirmed. The process of solid-phase metallization of pellets and extrusion briquettes (boex) from oolitic ores of the Ayatskoye deposit has been studied. A scheme for the manufacture of pellets and brex under laboratory conditions is presented and described. The results of reduction firing of specimens in CO atmosphere and in contact with solid carbon at temperatures of 1050 and 950 °C for three hours are presented. The mass loss of metallized pellets and brex was measured. The chemical composition of the regions of the original and reduced samples was studied by the X-ray microspectral method on an electron microscope. It has been established that at a temperature of 1050 °C, upon reduction with carbon monoxide, up to 0.6 at. %, and when reduced with solid carbon, the phosphorus content in the metal phase reaches up to 3.1 at. %. The results of the experiments confirm the possibility of selective reduction of iron without reduction of phosphorus with only carbon monoxide.
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Why is it important?
The demand for iron resources is growing rapidly due to the rapid development of the iron and steel industry. For this reason, the steel industry faces the risk of a shortage of raw materials. Iron ore deposits with a high phosphorus content are widely distributed throughout the world, but the use of these deposits in industry is limited due to the high phosphorus content, which affects the cost of the iron production process and the quality of the steel produced. A variety of hydrometallurgical and pyrometallurgical processes have been proposed for the use of oolitic iron ore with a high phosphorus content. However, these methods have disadvantages such as environmental pollution, cost inefficiency, excessive time consumption and low iron recovery.
Perspectives
Selective reduction of iron from oolitic ore with a high phosphorus content will further allow liquid-phase separation at temperatures above 1550°C. Reduction by gas will make it possible to switch to hydrogen metallurgy and selectively reduce iron with hydrogen or hydrogen-containing gases, which will reduce CO2 emissions.
Bakyt Suleimen
South Ural State University
Read the Original
This page is a summary of: Behavior of extrusion briquettes (Brex) and pellets from oolite iron ore in solid-phase metallization, January 2022, American Institute of Physics,
DOI: 10.1063/5.0075188.
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Resources
Selective Reduction of Iron and Phosphorus from Oolitic Ore
The possibility of selective solid-phase reduction of iron from oolitic ore has been experimentally confirmed. Solid phase reduction was carried out at temperatures of 850 and 1000°C in a CO atmosphere and in a mixture with solid carbon. Distribution of iron and phosphorus was investigated with a scanning electron microscope. It was found that at a temperature of 1000°C a minimum amount of phosphorus (up to 0.3%) is transformed into the metallic phase upon reduction with carbon monoxide. Upon reduction in a mixture of ore with carbon, the phosphorus content in the metal phase reaches 1.0–1.3% even at a temperature of 850°C. Thermodynamic modeling of the processes occurring during reductive roasting of oolitic ore was carried out depending on temperature (1000–1400 K) and amount of carbon in the system. It is shown that reduction temperature and degree of phosphorus reduction vary depending on the ratio of CO and CO2 in the gas phase. At temperatures below 892°C, phosphorus is not reduced, and all iron is in the metal phase. With an increase in the amount of carbon in the system, phosphorus appears in the metal phase. With an excess of carbon in the system, all phosphorus is in the metal phase at a temperature of 892°С. Thus, with a certain amount of carbon in the system and, correspondingly, with a certain ratio of CO and CO2 in the gas phase, selective reduction of iron is possible without phosphorus reduction even at a temperature of 1100°С. Comparison of experimental results with results of thermodynamic calculation confirms the possibility of selective reduction of iron without phosphorus reduction only by carbon monoxide.
Metallization of Oolitic Iron Ore after Oxidation Firing
iring and metallization of brown iron ore from the Ayat deposit were investigated in present research. In order to remove carbon dioxide, carbonates, hydrated moisture and sulfur from the ore and convert goethite to hematite the oxidation firing was carried out in a Nabertherm muffle furnace at temperature of 900 ° C for 10 minutes. The effect of reduction of temperature was studied, by CO gas at 800, 900, 1000, 1050 ° C, for 3hours reduction time. The chemical composition of the initial and fired ore, as well as magnetic and non-magnetic parts of the reduced samples were studied by using an electron microscope. It was observed that at temperature of 800 ° C iron and phosphorus were not reduced. The metallized material with a low phosphorus content (0.1at%) was obtained at temperature of 1050 ° C.
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