Study On The Dissolving Behavior Of Oxygen In Pressure Leaching Of Zinc Sulphide Concentrate

On the basis of a detailed review of direct leaching of zinc sulphide concentrate as wellas the dissolving behavior of oxygen, the low dissolving rate and utilization efficiency ofoxygen in the pressure direct leaching of zinc sulphide concentrate are proposed in thisdissertation. Thus, the study on the dissolving behavior of oxygen is carried out under thesimulating leaching conditions by autoclave. The main contents of this dissertation are asfollows:The atmospheric and pressure leaching temperatures are always set at110℃and150℃. So the experiments are respectively carried out under the temperatures stated above.Firstly, the influences of agitation speed, temperature, oxygen partial pressure, particle size ofconcentrate, amount of concentrate and active carbon are studied on the dissolving rate ofoxygen in pure water system and zinc sulphide slurry system respectively under no oxygeninlet pipe. The results show that the different agitation speeds in the range of400～800r/minhave the same influence on the dissolving of oxygen. The dissolving rate of oxygen increasesto the maximum with the increase of rotation time, which is followed by an obvious decreaseto an equilibrium. The dissolving rate of oxygen is changed with the agitation speed underdifferent temperatures. An optimum dissolving rate of oxygen can be achieved under110℃and800r/min, and the similar for150℃and500r/min. With the increase of temperature inthe range of90～160℃, the dissolving of oxygen is improved under some an oxygen partialpressure. So not only the dissolving of oxygen but the oxidization reaction is possiblyimproved. A much higher oxygen partial pressure is not always appropriate to the improvingof utilization efficiency. The oxygen partial pressure of0.5MPa is determined as appropriateunder110℃and800r/min, which is the same under150℃and500r/min. After zincsulphide concentrate is introduced in the pure water system, the dissolving rate of oxygen isimproved greatly and becomes to be higher and higher with the decrease of the particle sizeand the increase of the amount of concentrate. Moreover, the dissolving of oxygen can beeffectively improved with the addition of active carbon into the slurry system.The influences of agitation speed, temperature, oxygen partial pressure and the oxygeninlet pipe are further studied on the dissolving of oxygen. The results show that the dissolvingrate of oxygen is improved with the increase of oxygen inlet pipe length. The oxygendissolving of the multi-holes oxygen inlet is much better than that of single-hole inlet. Theinfluence of agitation speed in the range of400~800r/min on the dissolving of oxygen is similar to that of no pipe. Moreover, the influences of temperature, oxygen partial pressure arealso similar to those of no pipe. The oxygen pipe can promote the consuming rate of oxygento some extent during the pressure leaching of zinc sulphide concentrate. The leaching rate ofzinc can be improved by the oxygen inlet pipe although it has little influence on the kineticbehavior of zinc in leach.