滴加法制备铁黄颜料工艺研究

Study on the preparation of iron oxide yellow pigment by dropping method

采用滴加法制备铁黄颜料,即采用硫铁矿烧渣直接制得的硫酸亚铁及硫酸亚铁结晶母液为原料,用空气作氧化剂,用氨水作沉淀剂制晶种;在二步氧化中滴加氨水和硫酸亚铁结晶母液。探讨了亚铁浓度、空气流量等对晶种形成的影响,以及晶种比、空气流量、溶液pH、硫酸铵浓度等因素对铁黄生成的影响。确定了晶种制备和二步氧化的最佳工艺条件,即二步氧化中溶液pH控制在2.5～3.5,亚铁浓度控制在0.18～0.25mol/L的范围。检测结果表明:铁黄各项指标均达到原化工部HG/T2249—1991一级品标准。

The iron oxide yellow is prepared by dropping method,i.e.taking ferrous sulfate obtained from pyrite sintered residue and mother liquor of ferrous sulfate as raw materials,air as oxidizer and ammonia water as precipitant,the α-FeOOH crystal seed is prepared first,then the iron oxide yellow is formed by dropping ammonia water and mother liquor of ferrous sulfate in secondary oxidation.The influences of the concentration of ferrous sulfate and air flow on the crystal seed and the influences of crystal seed ratio,air flow,pH and concentration of ammonium sulfate on the iron oxide yellow are investigated.The optimum process conditions for the crystal seed preparation and secondary oxidation are determined.The pH of solution and concentration of ferrous sulfate in secondary oxidation are controlled in 2.5～3.5 and 0.18～0.25 mol/L respectively.The all index of finished product can meet the requirement of standard HG/T2249—1991 first grade product.