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Zinc Oxide Ores Of Ammonia To Strengthen The Leaching Method

Posted on:2010-08-13Degree:MasterType:Thesis
Country:ChinaCandidate:Y M ZhangFull Text:PDF
GTID:2191360278970527Subject:Metallurgical physical chemistry
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With the decreasing grade of current zinc concentrate ore, there is a growing emphasis on development and utilization of lower grade zinc oxide ore. A large quantity of extra acid will be consumed and the composition of leaching solution is complex when Zinc oxide ore is treated by acidic leaching processes .These lead to many unit operations to purify the solution and difficult to separate between solid and liquid. While it is higher selective to zinc with ammonia leaching of zinc oxide ores and other elements don't dissolve or their contents are extremely low in leaching solution, therefore, it shortens process flow and it is simple to purify leaching solution. However, high concentration of the leaching agent was used in ammonia leaching process, leading to precipitating ammonium and volatilizing losses of ammonia, so it needs to solve the problem in ammonia leaching process to increase leaching rate and reduce the concentration of the leaching agent.The samples are low-grade zinc oxide ore with high-silicon from Yunnan province and high-grade hemimorphite with the particle size below 100 mesh. This paper was about the leaching process of ore samples by ammonia-ammonium chloride solution in the absence or present of ultrasonic irradiation. It reviewed the effects of liquid-solid ratio, concentration of leaching agent and it's composition, temperature and time on zinc leaching ratio. At the same time, it focused on fundamental rules of influences of ultrasonic irradiation on the leaching process of oxide zinc ore.In the absence of ultrasonic, the optimum conditions of ammonia leaching of zinc from low-grate oxide zinc ore were determined as follows: 7.5 mol/L for total ammonia concentration, 2 for molar ratio of ammonium chloride to ammonia, 5 for liquid-solid ratio, 3 hours for leaching time, 30℃for reaction temperature and maximum leaching ratio of zinc 69.4% .While for hemimorphite, the optimum conditions are7.5 mol/L for total ammonia concentration, 1.5 for molar ratio of ammonium chloride to ammonia, 8 for liquid-solid ratio, 5 hours for leaching time, 30℃for reaction temperature and maximum leaching ratio of zinc 75.78%.The rules of influences of ultrasonic irradiation on the ammonia leaching process of oxide zinc ore and hemimorphite as follows:First, the influence of ultrasonic irradiation on zinc leaching process from low-grate oxide zinc ore and hemimorphite can improve leaching rate at lower temperature.Second, the influence of ultrasonic irradiation on zinc leaching process from low-grate oxide zinc ore is obvious at lower leaching agent concentration,while the influence of ultrasonic irradiation on zinc leaching process from low-grate oxide zinc ore is obvious at higher leaching agent concentration for hemimorphite.Third, it has been higher selectivity to zinc when ultrasonic irradiation on zinc ammonia leaching process of low-grate oxide zinc ore.Forth, it affects the dynamic behavior of leaching process of low-grate oxide zinc ore by ultrasonic radiation,but has a little influnce to thermodynamic behavior.
Keywords/Search Tags:ultrasonic irradiation, oxide zinc ore, hemimorphite, ammonia leaching, additive
PDF Full Text Request
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