Leaching mechanism of SiO₂ in activated kaolinite clinker with low modulus sodium silicate solution

ABSTRACT

Preparation of high modulus solution and high Al/Si residue via leaching SiO2 is a key for large amount utilization of coal gangue based on ferric oxide assisted roasting – alkali leaching silica process. This work focuses on leaching mechanism of SiO₂ in activated kaolinite clinker with low modulus sodium silicate solution. The results show that the lattice distorted cristobalite produced in the roasting process is readily soluble in sodium silicate solution, however the leaching of SiO₂ was only 75% and the modulus of lixiviant reached 2.5 through leaching in sodium silicate solution with a modulus of ~1.0. The leaching kinetics and dissolution mechanism have also been analyzed by model fitting and microstructural observation. The leaching reaction was controlled by diffusion across the pore. The slit – shaped pores formed by the stacking of hercynite particles prevent the diffusion of the bulk solution, thus inhibiting the leaching of cristobalite inside the particles.

KEYWORDS:

• Coal gangue
• activated roasting
• cristobalite
• sodium silicate solution
• leaching mechanism

Disclosure Statement

We declare that we do not have any commercial or associative interest that represents a conflict of interest in connection with the work submitted.

Credit Authorship Contribution Statement

Peng Wang: Conceptualization, Methodology, Data curation, Formal analysis, Investigation, Writing-original draft. Tiangui Qi: Conceptualization, Investigation, Validation, Writing-review & editing, Resources. Xiaobin Li: Investigation. Yilin Wang: Writing-review & editing. Leiting Shen: Writing-review & editing. Guihua Liu: Writing-review & editing. Zhihong Peng: Writing-review & editing. Qiusheng Zhou: Writing-review & editing.

Additional information

Funding

The work was supported by the National Key Research and Development Program of China [2022YFC3900901]; National Natural Science Foundation of China [51874366].