Research On Interface Measurement Of Sodium Aluminate Solution

Bayer process is a widely used method of production in modern alumina production process.Sedimentation and separation of crude sodium aluminate is an important part of the Bayer process.The process accelerates solution settling by adding flocculants to the subsidence layer.So,it is necessary to measure the interface between the sediment-sedimentation layer and the interface between the sedimentation-underflow layer to obtain the height of the sedimentation layer,calculate volume of sediment solution and determine the amount of flocculants.Currently,the mainly method to measure interface is based on artificial sample measuring,it has many disadvantages,such as long interval,large lag and fewer measurements,so the products quality can not be guaranteed.In view of the existing problems in the measurement of the sodium aluminate solution interface,ultrasonic method is used to measure the position of interface of sodium aluminate solution.Based on the propagation characteristics of acoustic wave in liquid and the structural characteristics of the probe,a longitudinal wave transducer is selected.And the ultrasonic transmitter circuit is based on the LM1812 ultrasonic integrated chip,the ultrasonic receiver and signal processing circuit are designed,peak detection method is used to realize signal detection.All designs match the measurement requirements.The STM32F103 microcontroller is used as the main controller,the peak voltage signal is collected by the build-in AD of main controller,and DS18B20 is used for temperature measurement.The C language is used to complete the STM32 microcontroller software preparation.The digital signal is processed by software filtering.The serial host computer software is completed with C#,which is used for experimental debugging.The thesis sets up a measuring platform under laboratory conditions,carries out solid content and interface measurement experiments,analyzes and processes the experimental data.Finally,the experiment has been completed calibration and debugging.Based on the theory of ultrasonic attenuation,it is feasible to analyze and detect the interface position of sodium aluminate solution in the settlement tank of alumina production.The volume of the solution in the settling layer can be indirectly obtained,which provides reference for the addition of flocculants.