A Novel Model of Aggregate Gradation for Autoclaved Bricks from Tailings

Tingting Zhang,Yunliang Zhao,Hongqiang Li,Wei Wang,Shaoxian Song,Qiwu Zhang,Hao Yi

doi:10.3390/min7070112

Tingting Zhang, Yunliang Zhao + Show 5 more

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https://doi.org/10.3390/min7070112

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Abstract

Mining tailings as a raw material for preparing autoclaved bricks have attracted much attention. The tailings subjected to milling always have the characteristic of fine granularity. However, the proportion of the fine aggregates in autoclaved bricks was very low using the current gradation formula, which impeded the utilization of the tailings. In this work, a novel model of aggregate gradation for autoclaved bricks from tailings has been presented, which was established through the following steps: (1) 91 groups of autoclaved bricks with different aggregate gradations were prepared, with the proportion of the fine aggregates (−0.15 mm) in the range of 40% to 100%; and (2) the particle size distributions of the finest and coarsest aggregates in the high-strength region were fitted to establish the model. The proportion of the fine aggregates calculated by the model could increase significantly compared with that using the current formula. To verify the novel model, autoclaved bricks from iron ore tailings were prepared using the model, with their mechanical and freezing resistance properties meeting the requirement of the highest-strength level. It was observed by SEM that the autoclaved bricks had compact structures with a few small pores owing to the reasonable aggregate gradation.

Highlights

IntroductionMassive tailings are discharged with the rapid development of the mining industry
Nowadays, massive tailings are discharged with the rapid development of the mining industry.The annual emission load of tailings in the world is more than 14 billion tons [1]
The location of the symbol in the ternary chart represents the contents of the fine, intermediate and coarse fractions in the bricks, and the form of the symbol demonstrates the compressive strength of the bricks

Summary

Introduction

Massive tailings are discharged with the rapid development of the mining industry. The annual emission load of tailings in the world is more than 14 billion tons [1]. The tailings are mainly stockpiled in tailings ponds occupying large areas of land [2,3]. There are some chemical agents and heavy metal ions remaining in tailings [4,5], which will transfer to other places and cause seriously negative impacts on the surrounding ecological environments [6,7]. The tailing ponds used to store the tailings are potential security issues. If the ponds are broken down, it will lead to great harm to the residents [8]. It is urgent to enhance the utilization rates of tailings

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