Valorisation of agricultural biomass‑ash with CO2

This work is part of a study of different types of plant-based biomass to elucidate their capacity for valorisation via a managed carbonation step involving gaseous carbon dioxide (co2). the perspectives for broader biomass waste valorisation was reviewed, followed by a proposed closed‑loop process for the valorisation of wood in earlier works. the present work newly focusses on combining agricultural biomass with mineralised co2. Here, the reactivity of selected agricultural biomass ashes with co2 and their ability to be bound by mineralised carbonate in a hardened product is examined. three categories of agricultural biomass residues, including shell, fibre and soft peel, were incinerated at 900 ± 25 °C. The biomass ashes were moistened (10% w/w) and moulded into cylindrical samples and exposed to 100% CO2 gas at 50% RH for 24 h, during which they cemented into hardened monolithic products. the calcia in ashes formed a negative relationship with ash yield and the microstructure of the carbonate‑cementing phase was distinct and related to the particular biomass feedstock. this work shows that in common with woody biomass residues, carbonated agricultural biomass ash‑based monoliths have potential as novel low‑carbon construction products

Characterization of Residual Carbon in Fly Ashes from Power Plants Firing Biomass

Fly ash samples were collected from grate fired power plant units burning mixed fuels of agricultural residues and woody biomass. The fly ashes were characterized in terms of the residual carbon mainly via nonisothermal thermogravimetric analysis (TGA) technique and loss-on-ignition (LOI) approach. TGA by heating of the fly ashes at 7 °C/min to 900 °C in air atmosphere showed three distinct peaks of weight loss in the temperature ranges of 350-530 °C, 530-660 °C, and 660-900 °C, which were confirmed to result mainly from the oxidation of residual carbon, the decomposition of calcium carbonate, and the release of alkali chlorides related species, respectively. It was shown that nonisothermal air TGA can distinguish the contribution of residual carbon oxidation to weight loss from those of the reactions of inorganic matter and, therefore, can be used as a simple technique for estimating the residual carbon content in biomass combustion fly ashes for engineering applications. The residual carbon content determined by TGA was compared with that from LOI measurements at 450 and 550 °C. The size distribution of the residual carbon in the fly ashes and the combustion reactivity of the residual carbon in large size fractions (>200 µm) of these fly ashes were also investigated, aiming at exploring the recovery and application of the residual carbon