酸性废水中和结晶工艺优化研究

Optimization of reactive crystallization process for acid wastewater

介绍了一种处理酸性废水的中和诱导法,先利用石灰乳中和混酸中的硫酸,得到二水硫酸钙,当pH值达到3~4时,加入氯化钙进一步除去硫酸根,最后用碳酸钠溶液除去多余的钙离子。在中和过程中,加入结晶诱导剂,并控制结晶条件,可得到晶型好、含水率低的CaSO_(4)·2H_(2)O晶体。对产品二水硫酸钙的浸出毒性试验表明,中和结晶过程得到的二水硫酸钙滤渣不属于危险废物。产品二水硫酸钙质量达到GB/T 23456—2009《磷石膏》中一级品的要求。

A neutralization induction method for treating acidic wastewater is introduced.The lime slurry is used to neutralize sulphuric acid in mixed acid to obtain calcium sulfate dihydrate,the calcium chloride is added to further remove sulfate ions when the pH value reaches 3-4,and the sodium carbonate solution is used to remove excess calcium ions.During the neutralization process,by adding a crystallization inducer and controlling the crystallization conditions,CaSO_(4)·2H_(2)O crystals with good crystal structure and low water content can be obtained.The leaching toxicity test of the product calcium sulfate dihydrate shows that the calcium sulfate dihydrate filter residue obtained during the neutralization crystalization process does not belong to hazardous waste.The product calcium sulfate dihydrate meets the requirements of Class I product in GB/T 23456-2009 Phosphogypsum.