90 / 2021-09-27 20:25:04

Carbonation of fluidized fly ashes and its possible increased application in mining engineering

mining,,coal fly ash (CFA)

In fluidized bed combustion, limestone is added to eliminate sulfur dioxide emissions. A side effect of this process is an increase in the free calcium oxide content of the fluidized fly ash (FFA) and fluidized bottom ash (FBA). This increased content of free CaO significantly limits the possibilities of using FFA in widely understood mining techniques related to economics and safety of mine operations.

Carbonation is the process in which carbon dioxide (CO2) reacts with various forms of calcium hydroxide to play an active role. It is a chemical process known in cement and concrete chemistry that affects the rheological properties of concretes, cement mortars, and the final strength parameters of concretes.

This analogy has inspired research work at the Central Mining Institute (GIG), which has resulted in a number of studies on the possible uses of this process to increase the utilization of this type of ash, including applications in mining techniques. Thus, two types of objectives can be achieved: improvement of the effectiveness and safety of mine operations, and adaptation of mines to work in compliance with the requirement of a closed-cycle economy combining coal mining with its use in fluidized bed combustion processes.

The carbonization of fluidized bed fly ash makes it possible to:

• reduce free calcium oxide content, which in turn reduces the chemical hazard


• eliminate free hydrogen emission from ash coming from co-combustion,


• increase the efficiency of sealing mine goafs by improving the penetration ability in the caving rubble,


• improve the stability of the binding processes of the self-desolidifying backfill and increase its resistance to the action of saline mine waters.

This paper presents the current state of research related to FFA carbonatization based on the autocatalytic process of the reaction of free CaO with CO2. It is indicated that carbon dioxide may be derived from sequestration technology in the future.



In fluidized bed combustion, limestone is added to eliminate sulfur dioxide emissions. A side effect of this process is an increase in the free calcium oxide content of the fluidized fly ash (FFA) and fluidized bottom ash (FBA). This increased content of free CaO significantly limits the possibilities of using FFA in widely understood mining techniques related to economics and safety of mine operations.

Carbonation is the process in which carbon dioxide (CO2) reacts with various forms of calcium hydroxide to play an active role. It is a chemical process known in cement and concrete chemistry that affects the rheological properties of concretes, cement mortars, and the final strength parameters of concretes.

This analogy has inspired research work at the Central Mining Institute (GIG), which has resulted in a number of studies on the possible uses of this process to increase the utilization of this type of ash, including applications in mining techniques. Thus, two types of objectives can be achieved: improvement of the effectiveness and safety of mine operations, and adaptation of mines to work in compliance with the requirement of a closed-cycle economy combining coal mining with its use in fluidized bed combustion processes.

The carbonization of fluidized bed fly ash makes it possible to:

• reduce free calcium oxide content, which in turn reduces the chemical hazard


• eliminate free hydrogen emission from ash coming from co-combustion,


• increase the efficiency of sealing mine goafs by improving the penetration ability in the caving rubble,


• improve the stability of the binding processes of the self-desolidifying backfill and increase its resistance to the action of saline mine waters.

This paper presents the current state of research related to FFA carbonatization based on the autocatalytic process of the reaction of free CaO with CO2. It is indicated that carbon dioxide may be derived from sequestration technology in the future.