Experimental Study to Investigate Physical and Mechanical Behavior of the Iron Ore Concentrate Tailings in Presence of Cementing Additive: A Case Study on West of Iran Steel Plant Waste

نوع: Type: Thesis

مقطع: Segment: masters

عنوان: Title: Experimental Study to Investigate Physical and Mechanical Behavior of the Iron Ore Concentrate Tailings in Presence of Cementing Additive: A Case Study on West of Iran Steel Plant Waste

ارائه دهنده: Provider: Shayan Hajji-Yusufi

اساتید راهنما: Supervisors: Dr. Mohammad Maleki

اساتید مشاور: Advisory Professors:

اساتید ممتحن یا داور: Examining professors or referees: Dr. Valid Reza Ouhadi, Dr. Abbas Qadimi

زمان و تاریخ ارائه: Time and date of presentation: 2025

مکان ارائه: Place of presentation: 45

چکیده: Abstract: Iron ore tailings are residual materials from the extraction and processing of iron ore, primarily composed of worthless minerals, silica, and heavy metals. Managing the massive volume of these tailings poses a significant environmental and technical challenge. From an environmental perspective, these materials threaten air quality, groundwater, and ecosystem health through the generation of toxic dust and the leakage of wastewater contaminated with heavy metals. Technically, these tailings, often in the form of thick slurry, exhibit poor mechanical stability and are susceptible to liquefaction and the failure of retaining dams. The conventional management method involves storage in specialized ponds. To mitigate risks, innovative techniques such as advanced dewatering to reduce volume and chemical stabilization with materials like cement are employed to enhance strength and neutralize heavy metals. This research investigates the physical, chemical, and mechanical properties of the tailings and assesses their environmental hazards. At the laboratory stage, physical tests such as particle size distribution and Atterberg limits, mechanical tests including compressive strength and triaxial tests, and chemical analyses like XRD and TCLP are conducted. Additives such as cement, lime, and fly ash are used to stabilize the tailings and improve their properties. In this study, the effect of chemical stabilization of iron ore tailings with 2%, 5%, and 8% by weight of cement, lime, fly ash, and metakaolin under varying moisture conditions and static/dynamic compaction was investigated. The studied tailings, classified as silt, have an internal friction angle of approximately 45 degrees. XRD and TCLP tests indicated that while the tailings are free of hazardous contaminants, their sulfur content is high. Results demonstrated that stabilization with a minimum of 8% cement not only completely neutralizes heavy metals but also leads to a strength increase equivalent to 4 MPa. In contrast, fully replacing cement with lime or substituting more than 20% of cement with fly ash or metakaolin resulted in a 60% reduction in strength. The samples in this study were subjected to static compactions of 25, 50, and 100 kg/cm² with energies of 300, 700, and 1600 kJ/m³, respectively. The compaction energy of 25 kg/cm² is half of the standard compaction energy, while the compaction energy of 50 kg/cm² is approximately 17% higher than the standard. The compaction energy of 100 kg/cm² is 41% lower than the modified compaction energy. Furthermore, increasing the strain rate from 0.5 to 1 mm per minute led to an 11.4% increase in ultimate strength. For samples stabilized with 5% and 8% cement, reductions in compaction rate resulted in strength increases of 13% and 8.7%, respectively.