本研究主要目的為探討結晶矽太陽能電池廠所產生的高濃度氫氟酸廢液，以氟化鈣製程進行研究，探討添加不同鈣鹽、pH值、加藥劑量等操作因子，對污泥中成份的影響，以提高污泥回收之效益。 研究結果顯示，原廢液pH值<0.1、氟離子值(F-)為16%，且含有硝酸、鹽酸、硫酸，屬於高濃度混酸廢液。以氟化鈣製程處理結果顯示，以添加CaCl2研究在Ca/F比=1劑量時，pH=8時所得到的污泥中有效氟化鈣濃度最高(92.57%)；其次為氫氧化鈣劑量在Ca/F比0.8時，pH=9時所得到的污泥中有效氟化鈣濃度最佳(87.67%)；碳酸鈣則以Ca/F比0.8時，pH=8時所得到的污泥中有效氟化鈣濃度最佳(79.70%)。而廢水中氟離子去除效率都有99.9%以上。 另加藥程序控制上氫氧化鈣及碳酸鈣皆只要簡單以pH值當加藥控制點，即可達到反應效果，但以氫氧化鈣pH=9效果最好，污泥中有效氟化鈣濃度高達87.67%；且操作成本低廉每噸廢液處理費用約1,950元，反應過程中也僅有放熱反應，溫度僅需控制在80℃以下即無危險產生。而碳酸鈣因溶解性極差，造成過多無效浪費，且最高污泥中有效氟化鈣僅達到79.70%，操作時亦會產生大量二氧化碳，有工安之虞。添加氯化鈣雖能使污泥中產生92.57%最高有效氟化鈣濃度，但仍只是冶金級規格，且另需添加液鹼造成成本最高，達到每噸廢液處理約11,800元，較無經濟上效益。且需特別計算Ca/F比避免浪費成本及降低污泥中有效氟化鈣濃度。 另因各實廠廢液因製程調整不同，廢液混酸成份亦不相同，經研究結果顯示，廢液中含有硫酸、二氧化矽成份，反應後會降低污泥中有效氟化鈣濃度。;The objectives of this thesis is to synthesis CaF2 using the high concentration of HF wastewater from the crystalline-silicon solar cells industry. The influences of the type of calcium, solution pH, and dosage on the composition of the recycled CaF2 were also investigated. The solution pH of the wastewater, which contained 16% HF, HNO3, HCl, and H2SO4, was lower than 0.1. The results showed that the recycled percentage of CaF2 is the highest (92.57%) when CaCl2 was added (Ca/F =1) at pH of 8. And the removal of F in all experiment was better than 99.9%. Besides, then Ca(OH)2 and CaCO3 were used, the recycle of CaF2 can be easily controlled by adjusting pH. When Ca(OH)2 was used, the chemical cost was the lowest. Though the reaction was exothermic, the operation is safe as long as the temperature was controlled below 80oC. Due to its low solubility, CaCO3 could not achieve high recycle percentage. Also, large amount of CO2 was produced. The recycled percentage was the highest when CaCl2 was used. However the quality of CaF2 is still not good enough. The adjustment of pH by NaOH also made the recycle of CaF2 by CaCl2 very expensive and not economic. In wastewater, other acids are usually present. The study also showed that when other acids are present in the wastewater, the amount of CaF2 would be reduced.
