| 摘要 |
<p>PURPOSE:To inexpensively recover an Na compound in refining slag at high purity with high efficiency by extracting an Na2O component in the slag, recovering Na2O by crystallization, making soluble impurities in filtrate after the crystallization slightly soluble, removing them, and returning the filtrate to the extracting vessel. CONSTITUTION:Refining slag 1 contg. an alkali metallic compound is pulverized and fed to an extracting vessel 2 to extract an Na2O component with an extracting soln. having >=4 apparent water ratio. A slurry 5 after the extraction is treated with a filter 6 to discharge undissolved residue 8 from the system. Part of the filtrate 9 is used as a refluxing soln. 10, and the remainder is fed to a crystallizing vessel 12 through a cooler 11 to crystallize Na2O. The Na2O crystallized slurry 15 is fed to a filter 16 to recover the Na2O 18. The filtrate 19 is fed to an impurity removing vessel 20, where it is reacted with an impulity impulity remover 21 made of the calcined product of dolomite or dolomitic lime, hydroxide thereof, or lime. By the reaction P, S and Si as soluble impurities in the filtrate 19 are made slightly soluble and separated as residue 26 with a filter 24. The filtrate is returned to the vessel 2 as a circulating soln. 27.</p> |
