响应曲面法优化镍转炉渣氧压选择性浸出工艺

为了优化镍转炉渣加压条件下H₂SO₄选择性浸出Co、Ni、Cu,抑制Fe浸出的工艺,采用响应曲面法的中心组合设计原理,建立影响选择性浸出率的二次多项式数学模型,研究浸出温度、c(H₂SO₄)及液固比及上述因素两两交互作用对提高Co、Ni、Cu浸出率及减少Fe浸出率的影响规律. 结果表明:浸出温度和c(H₂SO₄)对浸出率影响最显著,液固比次之. c(H₂SO₄)越高,Co、Ni、Cu和Fe的浸出率越高,而提高浸出温度有利于降低Fe浸出率. 响应曲面法优化获得的最佳工艺条件:浸出温度为210 ℃、c(H₂SO₄)为0.38 mol/L、液固比为4.25 mL/g,在该条件下,Co和Ni的浸出率均大于98%,Cu浸出率大于96%,Fe浸出率小于0.4%. 浸出控制参数优化后提高了有价金属的浸出率,同时也降低了Fe浸出率,实现了镍转炉渣中有价金属的回收及其与Fe的高效分离. 

Optimization of Pressure Oxidative Acid Leaching of Nickel Converter Slag by Response Surface Methodology

The objective of this study was to optimize the process for selective leaching nickel, cobalt and copper with the least iron extraction from nickel converter slag with sulfuric acid at elevated temperature and oxygen pressure. Central composite design of response surface methodology was employed to establish a quadratic equation model of selective extraction, and the effects of main factors such as leaching temperature, sulfuric acid concentration, ratio of liquid to solid and corresponding relationships between them on enhancing leaching rate of base metals such as nickel, cobalt and copper with lower iron extraction rate were studied. The effects of temperature and sulfuric acid concentration on the extraction were most significant, followed by liquid/solid (L/S) ratio. The higher the sulfuric acid concentration, the higher the extraction rates of nickel, cobalt, copper and iron, and it was good for lowering iron extraction to increase leaching temperature. The optimized parameters for the converter slag leaching were:temperature 210 ℃, sulfuric acid concentration 0.38 mol/L and L/S ratio 4.25 mL/g. Under the above conditions, more than 98% of Co and Ni and more than 96% of Cu were extracted into the solution together with less than 0.4% of Fe. In conclusion, effective recovery of base metals from nickel converter slag and high efficient separation of valuable metals from iron were achieved. The extraction of valuable metals can be improved with lower iron leaching rate after the parameters controlling the selective leaching process are optimized.