Decarbonization of Natural Lime-containing Materials and Reactivity of Calcined Products Towards SO2 and CO2

Abstract

The results obtained by studying decarbonization of different samples of Estonian limestone and dolomite and the following sulphation or carbonation of calcined products to estimate their SO2 and CO2 binding ability were presented. Experiments were carried out with thermogravimetric equipment(Q-Derivatograph, MOM and Labsys™, SETARAM) – calcination of the samples in the atmosphere of air with the heating rate 10 K per minute using multiplate crucibles, the following sulphation or carbonation of the calcined products after cooling to the fixed temperature (temperature range 400–900°C) under isothermal conditions in the flow of air-SO₂ or air-CO₂ mixture. Chemical, X-ray, BET nitrogen dynamic desorption, etc. methods for the characterization of the initial samples, intermediate and final products were used.

In addition, the possibilities of recurrent use of oil shale ashes taken from different technological points at operating thermal power plants (Estonian and Baltic TTPs, Estonia) as sorbents for SO₂ binding from gaseous phase were studied, as well as the possibilities of activation of these ashes towards SO₂ binding.

The results of these studies confirmed the high reactivity of Estonian limestone and dolomite towards SO₂ and CO₂. Dependence of SO₂ binding mechanism on the SO₂ concentration has been established. Modelling of SO₂ capture of dolomite and limestone was carried out to establish the kinetic parameters of these processes. The possibilities of activation of oil shale ashes and their effective recurrent use for binding SO₂ and CO₂ from gaseous phase were confirmed.