Mechanism of CO₂ Capture Technology Based on the Phosphogypsum Reduction Thermal Decomposition Process

Abstract

CO2 emission all over the world is constantly on the rise. In recent years, CO2 capture technology has been improved and innovated. Phosphogypsum (PG) is a solid product of industrial solid waste with an increasing annual accumulation. The research of this paper has carried out thermal decomposition of phosphogypsum under the reduction atmosphere to produce byproduct CaS and mineralization capture of CO2 in a gas–liquid–solid three-phase fluidized bed reactor. Results show that the fluidized bed is more effective and can effectually shorten the reaction time. Meanwhile, different liquid–solid (L/S) ratios, temperatures, and pressures have been researched to study the theory of CO2 capture by phosphogypsum. It has been found that the lower the L/S ratio is, the higher the CO2 capture capacity is. At the same time, theoretical calculations show that high temperature promotes the decomposition of CaCO3, thereby inhibiting the capture of CO2, so the whole carbonation process is operated under ambient temperature and pressure. Meanwhile, this paper discusses the calcium migration path and migration mode from the decomposition of PG to the mineralization of CO2, proposes a new idea of CO2 capture, and makes a certain contribution to PG resource utilization.

Effect of potassium feldspar on the decomposition rate of phosphogypsum

“…The weight loss of the subsequent three stages that occurred in the range from 410 °C to 1358 °C are 2.50%, 3.75%, and 43.00% (shown in Table 2), respectively. The weight loss of 6.25% (2.50% + 3.75%) in TG curve is attributed to both of these reactions (R 2 –R 4 ) 10,31 and the ignition loss of PG or coke in the range from 410 °C to 902 °C. The lower weight loss appeared at 1150 °C, which is attributed to the reaction between CaSO 4 and intermediate production of CaS (R 5 ) 10,32 .…”

“…The weight loss of 6.25% (2.50% + 3.75%) in TG curve is attributed to both of these reactions (R 2 –R 4 ) 10,31 and the ignition loss of PG or coke in the range from 410 °C to 902 °C. The lower weight loss appeared at 1150 °C, which is attributed to the reaction between CaSO 4 and intermediate production of CaS (R 5 ) 10,32 . During calcination, a small amount of coke may be oxidized to carbon monoxide reacting with PG (R 6 –R 7 ) 10 .…”

“…Generally, PG can produce sulfuric acid 3 and soil modifiers, 4 and it can also be used as raw materials for cement production or cement retarders, 5,6 among other functions. Due to the simplicity of operation, PG decomposition has been studied under various experimental conditions, such as using high‐sulfur coal, 7 anthracite, 8 or coke and lignite 9,10 as the reducing agent. The results showed that the higher the temperature adopted, the higher the content of CaO in the decomposition product can be obtained, and CaO is more suitable than CaS for the chemical industries.…”

Environmental Impact of Phosphogypsum-Derived Building Materials

“…Prismatic samples were prepared in accordance with UNE-EN 1015-2/A1 standards [33]. The samples were then deposited for 21 In the second stage, 2 g of the C_S sample was dispersed in 40 mL of distilled water under magnetic stirring in a reactor (mass ratio [C_S]/[H2O] = 1/20). A flow of CO2 (1 bar, 20 cm 3 /s) was bubbled through the suspension for 15 min at room temperature and pressure [1].…”

“…By means of other processes with PG, wastes, which are unable to fix CO 2 by themselves, can be successfully turned into effective CO 2 sinks [19]. CO 2 sequestration may also be achieved through mineral carbonation of waste PG using the technique of membrane electrolysis [20] and by the PG reduction thermal decomposition process [21].…”