Preparation And Application Of Continuous Temperature Measuring Device For Aluminium Electrolysis Cell

Electrolysis temperature is an important technical parameter for industrial aluminum electrolysis process.Timely,continuous and accurate measurement of electrolysis temperature is expected to realize invariably in aluminum electrolysis process.Measuring temperature by hands is widely used at home and abroad.Because of directly contacting the electrolyte,the measurement environment(high temperature,highly corrosive)is bad,Thermocouple is so easy corrosion that a protective ceramics tube is needed.This article is based on the research results of NiFe2O4 matrix inert anode for aluminum electrolysis.Slip casting is used in this work to produce protective ceramic sleeves for temperature thermocouple in aluminum electrolysis.This research result would lay a foundation for measuring temperature continuously in aluminum electrolysis.The slurry with 55.56%solid content,prepared by grinding the mixture consisted of 5%nano-binder and 10%NiFe2O4 nanopowder through ball mill process for 5 hours,exhibits good sedimentation stability.Smooth green bodies with no obvious holes on the surface and the uniform thickness of pipe wall were obtained by slip casting.Pretreatment on plaster model is taken in this work to overcome the problem of die adhesion in traditional slip casting.Smearing plaster powder on plaster model wall and putting a layer of paper between two semi-cylindrical models before slip casting favor to separate the green body and model effectively.For there are lots of drawbacks such as collapse and crack after the ejection,the plaster model should be wetted by water,where the suitable porosity,better water absorption and appropriate water content of the plaster mode is around 5 8%,43%and 15%according to the study of water content of the plaster mode.The rate of cracking can be reduced in the special sintering way,where the green bodies were placed vertically and filled with Al2O3 powders.Due to the large size of the green long sleeve placed in the air prone to cracks,so using double-sinter process method,the first pre-sintered at 1000 ? 1h and then a secondary sintering at 1350 ? 5h.At this time,the grains grow up and get closer each others,as a results,the pores gets less.Although the maximum thermal shock times reach to six,the thermal shock resistance of NiFe2O4 ceramic tubes should be improved enormously.Thermocouple performance results NiFe2O4 ceramic sleeve assembly was adopted showed that the thermocouple assembly in the simulation of electrolytic production process to heat up,add electrolytes,cooling,changing the input power and other process responsive,compared with thermocouple assembly sheathed thermocouple,thermocouple temperature difference between the two at 4 ? fluctuate up and down.Assembly thermocouple corrosion resistance was tested by static corrosion method,from before and after corrosion thermowells macro morphology,microstructure morphology changes and the change of the molten salt component in the process of corrosion can be drawn from three aspects:thermocouple assembly to withstand certain thermal shock effect and has good corrosion resistance to molten salt,with industrial application prospect.