SO2浸出软锰矿体系连二硫酸锰的生成机制

副产物连二硫酸锰(MnS₂O₆)生成是限制废气二氧化硫还原浸出软锰矿副产硫酸锰工艺工业化应用的技术瓶颈和关键科学问题。迄今,MnS₂O₆的生成机制尚未明确,难以为探究其工艺控制措施提供有效理论依据。基于此,本文研究了SO₂浸出软锰矿体系MnS₂O₆的生成机制,阐明了MnS₂O₆生成速率控制步骤和动力学过程。首先基于反应体系理论分析,提出基于表面吸附和电化学模型的自由基生成机制可用于解释MnS₂O₆的生成机制,其生成速率微观上取决于自由基HSO₃形成速率,宏观上主要取决于体系H^₊和HSO- 3浓度,两者的反应级数均为1,推导的理论生成速率方程为 。随后通过动力学实验考察了体系SO₂浓度、pH和温度对MnS₂O₆生成的影响,研究结果表明,MnS₂O₆生成速率随体系酸度和温度的升高呈现先快速减小后趋势趋缓,随体系SO₂浓度的升高而升高,H^₊和SO₂浓度对MnS₂O₆生成速率的反应级数分别为-0.057和0.9954,反应的活化能为6894.05 J/mol。最后基于液相SO₂解离平衡关系,推导得到H^₊浓度和HSO- 3浓度对MnS₂O₆生成速率的反应级数分别为0.943和0.996,与理论速率方程的级数非常接近。研究结果验证了对MnS₂O₆生成机制的解释和动力学推导过程, 可为该工艺工业化应用时MnS₂O₆生成特性及抑制方法研究提供理论依据和有效途径。

Formation Mechanism of Manganese Dithionate for Pyrolusite Leaching with SO2

The formation of manganese dithionate (MD) has become the key technical bottleneck and scientific problem for the extensive industry application of the technology of pyrolusite leaching process with sulfur dioxide waste gas. Hitherto, the formation mechanism of MD has not been ascertained, caused the lack of theoretical support for exploring the controlling measures of MD. Hence, for clarifying the rate-controlling steps and dynamic process of MD formation, the formation mechanism of MD was studied. Based on theoretical analysis, the free radical production mechanism derived from surface complexation and electrochemical model was imitated for explaining the formation mechanism of MD, which manifested that the formation rate of MD is depends on the production rate of HSO₃ free radical in microscopic scales and is determined by the concentration of H^₊ and HSO- 3 in macroscopic view, the reaction orders with respect to H^₊ and HSO- 3 are both 1, the derived theoretical equation for MD formation could be reported as follows . The dynamic experiments of SO₂ concentration, pH and temperature on MD formation were explored, the results showed that the MD formation rate was decreased rapidly firstly, and then decreased easing up with pH and temperature, while raised with higher SO₂ concentration, the calculated apparent activation energies for MD formation was 6894.05 J/mol, the reaction orders with respect to H^₊ and HSO- 3 concentration were -0.057and 0.9954 respectively, which was extremely close to the