A method for preparing a vaterite-type calcium carbonate using a fly ash water wash by-product

By controlling the pH value and the SO42-/CO32- molar ratio, aragonite-type calcium carbonate was prepared by using fly ash washing solution to remove hard by-products. This solved the problems of calcium resource waste and the complexity of aragonite preparation, and achieved the preparation of high-purity aragonite-type calcium carbonate and carbon dioxide fixation, which has both environmental and economic benefits.

CN122403480APending Publication Date: 2026-07-17HUNAN JUNXIN ENVIRONMENTAL PROTECTION CO LTD
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2026-04-15
Publication Date
2026-07-17

AI Technical Summary

Technical Problem

In existing technologies, the byproducts of fly ash washing solution for removing hardening are considered solid waste, resulting in a waste of calcium resources and increased secondary disposal costs. Furthermore, the preparation of aragonite-type calcium carbonate requires the addition of additives or complex processes, which affects product purity.

Method used

Using fly ash washing liquid as a raw material to remove hard byproducts, and by controlling the pH value and SO42-/CO32- molar ratio, calcium sulfate in the filter cake is used as a natural additive. The dynamic coupling reaction induces the formation of aragonite, avoiding the need for external additives, thus achieving the preparation of high-purity aragonite-type calcium carbonate.

Benefits of technology

This method enables the preparation of high-purity aragonite-type calcium carbonate, reducing production costs, simplifying the process, and achieving the secondary utilization of calcium resources and carbon dioxide fixation, resulting in significant environmental and economic benefits.

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Abstract

The application discloses a method for preparing ball spar type calcium carbonate by using fly ash water washing liquid to remove hard by-products, and comprises the following steps: removing hard of the fly ash water washing liquid to obtain a filter cake; mixing the filter cake with water to prepare slurry with a mass percentage concentration of 10-30%; introducing carbon dioxide-containing gas into the slurry, controlling the pH value of the system to be 9-10.5, the molar ratio of SO4 2‑ / CO3 2‑ being 0.2-1, and performing carbonization reaction until the pH value of the system is reduced to 7.5-8.5, stopping the introduction of carbon dioxide, and aging to obtain ball spar type calcium carbonate. The method of the application uses the filter cake of the fly ash water washing liquid to remove hard by-products as raw material, uses calcium sulfate in the filter cake as a crystal type regulator, controls the pH value of the system to be 9-10.5 and the molar ratio of SO4 2‑ / CO3 2‑ being 0.2-1, and thereby induces the generation of ball spar type calcium carbonate with high purity, large specific surface area and regular morphology.
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Citation Information

Patent Citations

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