Abstract
A new type of cemented paste backfill (CPB) was prepared using sodium hydroxide (NaOH) as the activator, slag and silica fume (SF) as the binder, and tailings as the aggregate. The effects of proportion of replacement of 0%, 5%, 10%, 15%, and 20% silica fume on the properties of CPB were studied. The strength formation mechanism of CPB was explored through a combination of scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and Fourier transform infrared (FTIR) spectroscopy. The SEM images were analyzed by IMAGE J software, and the porosity of CPB with different silica fume contents was obtained. The results show that as the amount of silica fume increases, the unconfined compressive strength (UCS) increases first and then decreases. When the amount of silica fume was approximately 5%, CPB with a larger UCS can be obtained. When the silica fume content increased from 0% to 5%, because silica fume has good activity and small particles, more calcium silicate hydrate (C–S–H) gels and Mg-Al type layered double hydrotalcites (LDHs) were generated in CPB, which made it denser and improved its strength compared with the non-silica fume group. C–S–H gels were the main source of CPB strength. With a further increase in the amount of silica fume, thaumasite produced inside of CPB, reducing the content of C–S–H gels. Moreover, due to the expansion of thaumasite, it is easy to generate a large number of micro cracks in CPB, which weakens the strength of CPB.
Highlights
Tailings are solid waste formed by the beneficiation of metal minerals
Under the action of the alkali-stimulated catalyst, a large amount of calcium silicate hydrate (C–S–H) gels and Mg–Al type layered double hydrotalcites (LDHs) were generated, which became the main source of cemented paste backfill (CPB) strength
C–S–H gels were the main source of CPB strength
Summary
Tailings are solid waste formed by the beneficiation of metal minerals. According to statistics, the global average annual tailings output exceeds 10 billion tons and will continue to grow in the future [1,2].The tailings discharged from a concentrator are often stacked into tailings dams. Tailings are solid waste formed by the beneficiation of metal minerals. Accidents caused by dam breaks in tailings dams are common worldwide, and untreated tailings containing heavy metals that can contaminate land resources and groundwater resources, cause atmospheric pollution and endanger human health [3,4,5]. These issues have led many countries to undertake enormous fiscal expenditures to manage idle tailings [6]. As a by-product of the metallurgical industry, silica fume (SF)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
