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In the cemented paste backfill (CPB) method, which can also be used for fortification purposes in mines, different additive materials with pozzolanic properties can be employed as substitutes instead of cement that is the main binder. One of the most popular pozzolanic materials that can be employed instead of cement is fly ash, which is thermal power plant tailings. But the compositions of fly ash and tailings used in high amounts in the CPB method, as well as the chemical structures that these materials form by interacting with the cement binder, affect the mechanical properties of the material depending on time. In this study, fly ash with 4 different chemical compositions (TFA, SFA, YFA, and CFA) was used as a cement substitute in CPB. By substituting fly ash with different chemical compositions in different proportions, CPB samples were created and their strength was elucidated according to 28, 56, and 90-day curing times. The results of the study revealed that TFA with the highest CaO/SiO2 and SO3 ratios remained stable at the strength values of 6 MPa (total 9% binder) and 10 MPa (total 11% binder) in the long term. However, CFA with the lowest CaO/SiO2, SO3, and the highest SiO2+Al2O3+Fe2O3 ratios resulted in the greatest strength increase at a 20% substitution rate (11% of the total binder). Nevertheless, it was found that the SFA, which is in Class F, increased its strength in the early period based on the CaO rate. [ABSTRACT FROM AUTHOR]

Cemented paste backfill system used for the storage of tailings underground also serves as support against subsidence due to roof loads. Therefore, paste backfill materials should be optimized according to strength, environment, and cost requirements. The main purpose of this study is to determine the ratio and optimal particle size distribution of zeolite which is one of the natural pozzolanic materials and can substitute cement in paste backfill. As a result of the experiments without zeolite, it was determined that paste backfill materials with the cement ratio of 9% and 11% can be used for ground support instead of the cemented paste backfill reference samples with 80% solid content. Then, zeolite-substituted samples were prepared in 2 different particle sizes of − 90 μm and − 180 μm at cement ratios of 5%, 10%, 15%, and 20%. Then, the effects of the paste backfill materials on the strength of curing periods of 28, 56, and 90 days were examined. As a result, it was found that 9% cemented paste backfills with 15% zeolite substitutes (− 90 μm) and 11% cemented paste backfills with 10% zeolite substitutes (− 180 μm) could be used in paste backfill. Also, 11% cemented paste backfills with 10% zeolite substitutes (− 180 μm) provide better strength depending on the curing times. [ABSTRACT FROM AUTHOR]

There are only a few pilot schemes, especially among scientific studies carried out to solve numerous environmental and ecological problems created by water during tailing storage on the surface. It is extremely important to establish precautions that can be taken, especially in the tailing storage process by examining the physical, chemical, mineralogical, and geotechnical changes that develop due to the effect of moisture in the tailing and surface water. In this study, 2 different pilot-scale designs of storage with no additions (reference) and with binder additions (cement and fly ash) to some layers were observed in field conditions for about 1 year to determine the effects of seasonal changes on paste material. The results of the measurements revealed that the water content of the reference design was ~ 10% higher than that of the design with cement addition at the substrates that provide stability and sudden temperature changes at the top layer of the reference design was found to be ~ 35 °C. Maximum sudden temperature changes in layers with cement addition and layers with cement and fly ash addition were observed to be ~ 15 °C. As a result, the use of cement has made the material more resistant to external factors. However, the study also revealed that fly ash could be used instead of cement with a substitute rate of 50% to reduce the cost for long-term storage in terms of industrial applications. [ABSTRACT FROM AUTHOR]

Surface paste disposal method can be used to minimize environmental risks during storage of mine process tailings. There are some researches and industrial applications which prove success of the method. The surface paste disposal of mineral process tailings obtained from a Pb-Zn underground mine was simulated considering mine site conditions at laboratory scale in the study. The paste material was stored in the cabin/container layer by layer, and then, the cracks occurred after the paste formation of each layer were analyzed by image process. Meanwhile, leachate water collected from the bottom of the cabin was subjected to electrical conductivity (EC) analysis. Furthermore, the wetting-drying process was conducted to simulate the climatic conditions of the region. Additionally, some physical and geochemical parameters such as matric suction, volumetric water content, and oxygen consumption of the paste material were obtained using sensors displaced into different layers. The results of the crack analysis for each layer showed that the cracks intensity increased at lower layers. Moreover, the crack intensity and EC values of each layer showed a similar trend, and the crack intensity increased almost five times during the wetting-drying tests. The measured values of the parameters obtained from the tests indicated that the deposited paste material can be stabile during the deposition over the years under the climatic conditions of the region. [ABSTRACT FROM AUTHOR]