Pelletizing of ferruginous quartzites with red mud addition and heat treatment of obtained pellets in carbon monoxide atmosphere
Year: 2024
Type: article
Abstract: Use of concentrates with coarseness from 0.063 mm and lower as metallurgical raw material, is possible only after their corresponding enlargement, what is a complicated problem. This research describes comminution of ferruginous quartzites at first, and then sieving in the screen with coarseness < 0.063 mm. Red mud from Ural aluminium works was added as a binder. To increase pelletizing degree, the technique of red mud powdering on charge surface by compressed air was suggested. Charge humidity makes 6–9 % due to presence of high-dispersed clay of fine-porous particles with high moisture capacity in this charge. It was established that tensile strength during compression of green pellets with diameter 14–16 mm, which were obtained via this method, are 2 kg per a pellet. Aggregation of separate grains is noted already at the temperature 200–300 °C, what is explained by their partial surface oxidizing in hematite; at the same time, strength of pellets increases. It was also established that red mud addition during pelletizing of ferruginous quartzites is sufficient in the amount up to 5 %, while magnetite crystals show good aggregation with each other at the temperature 900 °C in reducing atmosphere of carbon monoxide, what leads to recrystallization of magnetite grains with forming of magnetite binding. The forming processes of slag, silica and quartzite are passing in the neutral media at the temperature 1000–1200 °C. It was found out that pellets with diameter 14–16 mm from ferruginous quartzites, which are subjected to roasting up to 1100 °C in reducing atmosphere, have hematite binding with relatively low strength. When increasing the temperature up to 1290 °C, pellets reach their tensile strength during compression up to 240–250 kg per a pellet. It was also found out that a sample at the temperature 1290 °C presents dense magnetite concentration in the central part of a pellet and melting of grains around their periphery provides strong structure; in this case qualitative composition of a pellet varies during phase transition of oxides from hematite to wustites.
Source: CIS Iron and Steel Review
Author: A. B. Lebedev
Institution: Saint Petersburg Mining University
Language: English
Subfield: Mechanical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W4405371695