ACID DISSOLUTION STUDIES OF BRAZILIAN SERPENTINITE ROCKS APPLIED TO MINERAL CARBONATION PROCESSES
Kely Regina Maximo Vieira1; Gretta Larisa Aurora Arce Ferrufino2; Ivonete Ávila1; Vitor Oliveira Facio1; João Andrade de Carvalho Jr.1; Turibio Gomes Soares Neto2
1 UNESP - Univ Estadual Paulista, Faculty of Engineering at Guaratinguetá.; 2 National Institute for Space Research, combustion and propulsion associated Laboratory.
doi:10.20906/CPS/COB-2015-1112
Resumo
The actual demand of energy leads to an increase in fossil fuel consumption, which causes the need of insertion of carbon capture and sequestration (CCS) technologies and together with other forms of mitigation of carbon dioxide (CO2) can reduce the environmental impact related to the use of fossil fuels. The mineral carbonation is a CCS technology that fixes CO2 in form of insoluble carbonates. These carbonates could be used as raw material in others industrial sectors. Among all the mineral carbonation processes, the indirect mineral carbonation involves the acid dissolution stage. In this process, metals such as Mg, Ca and Fe are extracted from the raw material, to further react with CO2. The serpentinite rocks is known for having considerable concentrations of Ca, Mg and Fe within its structure and is one of the raw materials used in this process, whereas these rocks are found in considerable amounts in Brazil. The aim of this study is to obtain the highest percentage of Mg extraction in acid dissolution stage of serpentinite rocks, since minor extractions may invalidate this technology economically. In this study it was used the brazilian serpentinite from the Minas Gerais state (S-MG). The acid dissolution consists of two stages. In the first stage involves the dissolution reaction to extract magnesium from the serpentinite rock using hydrochloric acid (Mg3Si2O5(OH)4 + 6HCl = 5H2O + 2SiO2 + 3MgCl2). In the second stage the carbonation reaction is performed by injecting CO2 in the MgCl2 solution and to stabilize the hydrogen potential (pH) a sodium hydroxide (NaOH) aqueous solution is used (5MgCl2 + 10Na(OH) + 4CO2 = 3NaCl + Mg5 (OH)2(CO3)4.4H2O). Design of experiments (DOE) is used, which considers factors that influence the reaction, such as temperature, hydrochloric acid concentration and particle size of the raw material. The analysis identifies the levels of factors that presented highest percentage of Mg extraction in this process. The results can help on development of the indirect mineral carbonation
Palavras-chave: Carbon dioxide; Serpentinite; Mineral carbonation; Acid dissolution; Carbon capture