- 學位論文
由蛇紋岩廢料回收氧化鎂及非晶質二氧化矽
The Recovery of Magnesium Oxide and Amorphous Silica from Serpentinite waste
摘要
本研究將蛇紋岩切割廢料作為原料，製備高純度氧化鎂及非晶質二氧化矽。首先將蛇紋岩粉末經磁選，再以鹽酸浸漬，酸浸殘留物利用重力沉降分離。再以二次酸浸製備不同粒徑之非晶質二氧化矽，酸浸液則利用純化及高溫水解製程製備氧化鎂。探討酸浸製程參數如酸濃度、反應溫度、反應時間及液固比對鎂浸出率之影響。利用反應動力學模型建立各參數間彼此關係，並從中找出最適化參數。由酸浸殘留物製備的非晶質二氧化矽，其粒徑、純度受酸浸參數及沉降分離時間控制。非晶質二氧化矽表面佈滿水鎂石層受酸蝕形成的孔隙，粒徑多在次微米至微米級之間。由酸浸液製備的氧化鎂純度受中和沉澱過程pH值控制，製程所得的氫氧化鎂在煆燒400℃、一小時後形成方鎂石相之氧化鎂，其純度可達99.5％ 。本研究利用ICP、AA、EDS進行化學成分分析，並以TG/DTA、SEM、XRD及FTIR分別進行礦物熱性質、微結構、相組成及化學組成分析。
並列摘要
The serpentinite waste was utilized as raw materials to prepare amorphous silica and magnesium oxide in this research. The serpentinite powders were conducted by wet magnetic separation method to delete magnetite in the first, then leached by hydrochloride acid to obtain magnesium solution . The leaching residuals were then treated by gravity separation and further leaching process to ensure obtaining pure amorphous silica. The leaching liquor was then purified and hydrolyzed to recover magnesium hydroxide. The optimum conditions for leaching of Mg2+ from serpentinite powders were determined by the kinetic equation of leaching, and by which the relationship of the main factors which affecting the leaching rate such as acid concentration, leaching time, leaching temperature and liquid-solid ratio can be constructed. The pores due to the dissolution of magnesium hydroxide were distributed on the surface of amorphous silica prepared by leaching residuals using hydrochloride acid. The particle sizes of amorphous silica are distributed between few micron and submicron. The purity of magnesium oxide prepared by leaching liquor was mainly influenced by pH value during purification process. The MgO with periclase phase and the purity of 99.5% can be obtained by calcining the magnesium hydroxide at 400℃ for one hour. The chemical analysis and characterization of samples were conducted by ICP, AA, EDS, TG/DTA, SEM, XRD, and FTIR.
參考文獻
延伸閱讀
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