Mineralização de CO2 em efluentes salinos

Abstract

The aim of this study was to study the mineralization of carbon dioxide in synthetic solutions that simulate saline industrial effluents and includes the potential for carbon sequestration. In various industrial processes such as the process of obtaining potassium by solution mining or in the oil industry, fossil fuels are burnt concurrently to generate saline effluent. The opportunity to sequester carbon through capturing the carbon dioxide from the flue gas and subsequently performing the carbonation of these effluents is evident, with the reduction of atmospheric emissions also, depending on the reaction products obtained, the potential reduction of fouling or even commercial use of the precipitates generated is possible. The carbonation reaction was simulated through OLI® software using two types of effluents: reverse electrodialysis concentrate and solution mining effluents (from carnallite processing). This choice is in the nature of the brine. The reverse electrodialysis concentrate can exhibit low ionic strength, while the solution mining effluent generally has high ionic strength before preparation for disposal in water bodies. Laboratory scale experiments were then performed on both. The solution ehich was characterized and also the obtained solid identified. Results from the simulation and the laboratory experiments were then compared. The simulation results were in line with the experimental results for synthetic solution of reverse electrodialysis concentrate. It showed very positive results for the reduction of calcium and strontium grades in solution, while also precipitating carbonates. This result leads to the carbon sequestration but also to reducing the potential effect of fouling in this type of solution, thus increasing the chances of water reuse. However, with the solution simulating the dissolution mining effluent, the most abundant constituent being magnesium, the results showed an amorphous solid which not only contained carbonates, but also hydroxide, which may compete with the formation of carbonates. The carbonation reaction involving magnesium and more complex ionic environments requires further investigations.