Variation law of gas holdup in an autoclave during the pressure leaching process by using a mixed-flow agitator

• Published in: International journal of minerals, metallurgy and materials Vol. 24; no. 8; pp. 876 - 883
• Main Authors: Tian, Lei, Liu, Yan, Tang, Jun-jie, Lü, Guo-zhi, Zhang, Ting-an
• Format: Journal Article
• Language: English
• Published: Beijing University of Science and Technology Beijing 01.08.2017; Springer Nature B.V; Key Laboratory of Ecological Utilization of Multi-Metal Intergrown Ores of the Ministry of Education, School of Materials and Metalurgy, Northeastern University, Shenyang 110819, China; School of Metalurgical and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, China%Key Laboratory of Ecological Utilization of Multi-Metal Intergrown Ores of the Ministry of Education, School of Materials and Metalurgy, Northeastern University, Shenyang 110819, China
• Subjects: Agitation; Autoclaves; Bubbles; Cameras; Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Composites; Corrosion and Coatings; Empirical equations; Glass; High speed cameras; Leaching; Liquid phases; Materials Science; Metallic Materials; Metallurgy; Natural Materials; Oxygen; Partial pressure; Photography; Pressure leaching; Quartz; Silicones; Similarity theory; Solid phases; Sulfuric acid; Surfaces and Interfaces; Temperature; Thin Films; Tribology; Turbines; autoclave; pressure leaching; empirical equation; mixed-flow agitator; variation law; gas holdup
• ISSN: 1674-4799; 1869-103X
• DOI: 10.1007/s12613-017-1473-7

The multiphase reaction process of pressure leaching is mainly carried out in the liquid phase. Therefore, gas holdup is essential for the gas–liquid–solid phase reaction and the extraction rate of valuable metals. In this paper, a transparent quartz autoclave, a six blades disc turbine-type agitator, and a high-speed camera were used to investigate the gas holdup of the pressure leaching process. Furthermore, experiments determining the effects of agitation rate, temperature, and oxygen partial pressure on gas holdup were carried out. The results showed that when the agitation rate increased from 350 to 600 r/min, the gas holdup increased from 0.10% to 0.64%. When the temperature increased from 363 to 423 K, the gas holdup increased from 0.14% to 0.20%. When the oxygen partial pressure increased from 0.1 to 0.8 MPa, the gas holdup increased from 0.13% to 0.19%. A similar criteria relationship was established by Homogeneous Principle and Buckingham’s theorem. Comprehensively, empirical equation of gas holdup was deduced on the basis of experimental data and the similarity theory, where the criterion equation was determined as ε=4.54×10-11n3.65T2.08Pg0.18. It can be seen from the formula that agitation rate made the most important impact on gas holdup in the pressure leaching process using the mixed-flow agitator.