【摘要】 水热臭葱石沉砷体系中Na⁺、K⁺碱金属离子对沉砷渣物相组成影响显著，Fe（Ⅲ）与As（Ⅴ）共沉淀生成臭葱石（FeAsO₄·2H₂O）、次水合砷酸铁（FeAsO₄·0.75H₂O）砷铁共沉淀物，同时Fe（Ⅲ）还以黄钠铁矾（NaFe₃（SO₄）₂（OH）₆）、黄钾铁矾（KFe₃（SO₄）₂（OH）₆）、碱式硫酸铁（Fe（OH）SO₄）形态竞争析出，从而影响沉砷渣的稳定性。在Na₂SO₄-（K₂SO₄）-FeSO₄-H₃AsO₄-H₂O体系中研究了Na⁺、K⁺的存在及其浓度变化对砷铁沉淀率、沉砷渣物相组成及转变规律和沉砷渣稳定性的影响。结果表明：当体系Na⁺、K⁺共存时，砷、铁沉淀率分别为98.6%、94.5%,获得以臭葱石、黄钾铁矾及黄钠铁矾为主并伴有少量碱式硫酸铁的沉砷渣，沉砷渣含As 21.2%、Fe 27.1%、Na 0.2%,K 2.0%、S 4.84%。亚稳态铁矾物相的生成导致沉砷渣浸出毒性试验中As浓度超过标准限值（5 mg/L）,通过控制初始铁砷摩尔比，适当升高反应温度、延长反应时间可抑制铁矾物相的形成或促进其转化为臭葱石物相。更多还原

【Abstract】 The effect of alkali metal ions of Na⁺ and K⁺ on phase composition of As-bearing precipitate in hydrothermal arsenic solidization system is remarkable.In addition to co-precipitation with As（Ⅴ） to form scorodite（FeAsO₄·2H₂O） and sub-hydrous ferric arsenate（FeAsO₄·0.75H₂O）,Fe（Ⅲ） will also competitively precipitate as Na-jarosite（NaFe₃（SO₄）₂（OH）₆）,K-jarosite（KFe₃（SO₄）₂（OH）₆） or basic ferric sulfate Fe（OH）SO₄,thereby affect the stability of As-bearing precipitate.The effect of Na⁺ and K⁺ on precipitation rate of arsenic and iron, composition of precipitate, transformation of mineral phase, and the stability of precipitated were studied in the system of Na₂SO₄-（K₂SO₄）-FeSO₄-H₃AsO₄-H₂O.The results show that with the co-existing of Na⁺ and K⁺,the precipitation rate of As and Fe is 98.6% and 94.5% respectively, and the As-bearing precipitate mainly composed of scorodite, Na-jarosite, K-jarosite, and is concomitant with a small amount of basic ferric sulfate.The precipitate contains As 21.2%,Fe 27.1%,Na 0.2%,K 2.0% and S 4.84%.The formation of metastable phase of jarosite causes As concentration exceeds the standard limit（5 mg/L） in the leaching toxicity test of As-bearing precipitate residue.Increasing reaction temperature and prolonging reaction time can inhibit the formation of jarosite phase or promote its transformation into scorodite.更多还原