Using the Biocarbonization of Reactive Magnesia to Cure Electrolytic Manganese Residue
2021
Chen, Zhe | Fang, Xiangwei | Long, Kaiquan | Shen, Chunni | Yang, Yang | Liu, Jinlong
A new method for curing electrolytic manganese residue (EMR) using the biocarbonization of reactive MgO (r-MgO) is presented in this paper. This method uses microbial technology to provide CO₂ to react with r-MgO then strengthen the EMR and reduce its heavy-metal content, which combines the advantage of r-MgO solidification technology and microbial technology. Several parameters include the content of r-MgO and urea, initial moisture content, and age that affect the moisture content, dry density, pH, unconfined compressive strength, stress–strain curve, and microstructure of solidified EMR are studied, and the solidification mechanism of EMR using the biocarbonization of r-MgO is discussed. The results show that the hydration of r-MgO generates brucite can reduce the moisture content and increase the dry density and pH. The CO₂ produced by the hydrolysis of urea with bacteria reacts with brucite to produce nesquehonite, hydromagnesite, and other carbonized products that further reduce the moisture content and increase the dry density. This process can bridge particles and fill pores, consequently improving the EMR strength. At early age, the biocarbonated EMR samples can reach 5.22 MPa at 12 h. This shows the biocarbonization of r-MgO is effective for solidifying EMR.
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