(1. 桂林理工大學(xué) 材料科學(xué)與工程學(xué)院 廣西高校有色金屬清潔冶煉與綜合利用重點實驗室，桂林 541004； 2. 中南大學(xué) 冶金與環(huán)境學(xué)院，長沙 410083)
摘 要: 除鐵是鋅濕法冶金過程的重要步驟。磷酸鹽沉淀法相比于傳統(tǒng)的鐵礬、針鐵礦和赤鐵礦沉淀法具有明顯的優(yōu)勢。針對磷酸鹽沉淀法的從硫酸鋅溶液中凈化除鐵過程進行熱力學(xué)分析，繪制了298 K時Men+-P-H2O(Me：Zn(II)，Cu(II)，F(xiàn)e(II)，F(xiàn)e(III)，Ni(II))系組濃度對數(shù)-pH圖，利用熱力學(xué)平衡圖對磷酸鹽沉淀法的從硫酸鋅溶液中凈化除鐵和磷酸鐵堿分解過程進行熱力學(xué)分析。結(jié)果表明：pH值為0~5.0時磷酸鹽形成由易至難依次為 Fe(III)＞＞Cu(II)＞Fe(II) ＞＞Zn(II)＞Ni(II)；整個pH值范圍可以分為難溶磷酸鹽穩(wěn)定區(qū)、Me(OH)n穩(wěn)定區(qū)；高pH區(qū)磷酸鹽中的Me轉(zhuǎn)變?yōu)榉€(wěn)定的Me(OH)n，實現(xiàn)磷酸鹽堿分解。驗證實驗表明，加入1.0倍理論量的磷酸鈉，控制沉淀pH值為2.0，鐵、鋅、銅、鎳沉淀率分別為98.9%、3.5%、2.8%、0.7%；FePO4與其2.0倍物質(zhì)量的NaOH反應(yīng)，產(chǎn)物為Fe(OH)3、Na2HPO4，磷浸出率為96.8%，分解液pH為11.3，實驗與理論相符。
關(guān)鍵字: 磷酸鹽；鐵；鋅；沉淀；熱力學(xué)
（1. Guangxi Key Laboratory in Universities of Clean Metallurgy and Comprehensive Utilization for Non-ferrous Metals Resources, School of Materials Science and Engineering, Guilin University of Technology, Guilin 541004, China; 2. School of Metallurgy and Environment, Central South University, Changsha 410083, China）
Abstract:Removing iron is the key process of extraction zinc by hydrometallurgy. The removing iron from leach solution by means of phosphate precipitation may be a feasible alternative to conventional precipitation processes as jarosite, goethite or hematite. Aiming at removing iron by phosphate precipitation, the logarithm concentration-pH diagram of Men+-P-H2O(Me：Zn(II), Cu(II), Fe(II), Fe(III), Ni(II)) system was established on the basis of thermodynamic data at 298 K, according to the laws of conservation of mass and simultaneous equilibria. Themodynamic analysis was carried out to discuss the process of removing iron from lixivium of zinc calcine by phosphate precipitation and decomposition of iron phosphate by sodium hydroxide. The results show that the ions can be removed respectively by phosphate precipitation in the following order: Fe(III)＞＞Cu(II)＞Fe(II) ＞＞Zn(II)＞Ni(II). The whole pH value of the system is divided into two areas. The one is the stable of sparingly soluble phosphate, the other is Me(OH)n. Me(OH)n is gradually superaturated in the solution with the increase of pH value, so the Me(OH)n is deposited as sediment, and phosphate goes into solution. The verification experiment results showed that the precipitation rate of Fe, Zn, Cu and Ni were 98.9%, 3.5%, 2.8% and 0.7%, respectively, by 100% theoretical amounts of sodium phosphate at pH 2.0. When the dosage of NaOH is 2.0 times of the mole ratio of FePO4, FePO4 decomposed into Fe(OH)3 precipitate and Na2HPO4, phosphorus leaching rate is 96.8%, the pH value of leaching liquid is 11.3, which is consistent with the thermodynamic analysis.
Key words: phosphate; iron; zinc; precipitation; thermodynamic
