Research On Molten Steel Level Measurement Method Based On Molten Salt Electrochemistry

The measurement of the steel level of the tundish with molten coating is an important part to ensure the smooth progress of the continuous casting production process,and is also an important part to ensure the output and quality of the product.Since the molten steel temperature is around 1600?,the high temperature and dusty harsh environment makes the traditional detection method difficult to be applied in actual production.Therefore,the tundish steel water level measurement is still a failure to solve in the metallurgical process.Since the steel water layer has slag,the article proposes a molten steel liquid level measurement scheme based on molten salt electrochemistry,which realizes real-time measurement of the tundish liquid level by utilizing the difference in electrochemical characteristics between molten steel and molten slag and in the laboratory environment and the field environment,The main research contents are as follows:(1)The electrochemical properties of molten coating agent and the principle of molten steel liquid level measurement based on molten salt electrochemistry were studied.Firstly,the chemical composition and ionic structure of the molten coating agent were analyzed.Secondly,the influence of the melting state of the molten coating agent on the conductivity and oxidizing property was analyzed.Finally,the oxidative property of the molten covering agent was used to analyze the free energy spectrum according to Gibbs.The stability of each chemical component was analyzed,and the experimental principle of measuring the molten steel level with an electrode was analyzed based on the difference in stability.(2)In the laboratory environment,research of electrode used to measure the general applicability,accuracy and service life of molten steel liquid level.Firstly,the experimental method is designed according to the measurement principle.The electrode materials studied and used are mainly graphite,tantalum,tungsten and molybdenum.The actual measurement is carried out by means of two different material electrodes simultaneously lifting and lowering;secondly,the general applicability of the measurement method is analyzed(consideration whether the voltage jump signal obtained by the experiment is stable),design different ratio experiments of molten covering agent,and deeply study the measurement error and electrode service life under different ratio conditions;finally,based on the verification of the applicable method,the analysis The effect of different electrode materials(mainly graphite-tungsten,tantalum-tungsten)on the voltage signal in the experiment.Aiming at the problem of interference signals in the laboratory environment,the applied voltage method was designed,and the influence of the method on the electrochemical characteristics was analyzed and studied.(3)In the field experiment,the stability of voltage signals obtained by different electrode materials was studied,and the internal electrochemical reaction mechanism was deeply explored.Firstly,according to the on-site environment of the steel mill,the feasibility of the single-electrode lifting experiment method was designed and analyzed.Secondly,various inert metals were selected for experimental comparison,such as molybdenum,tungsten,titanium,chromium,zirconium,niobium and tantalum,in order to find out electrode material which can stably obtain the voltage signal and measure the sustainability.Finally,the applied voltage method relieves the electromagnetic interference signal to a certain extent,and makes the thickness of the molten covering agent measurable,and the average measurement error is 3 mm.According to the analysis,the following conclusions can be drawn:Firstly:The unstable substance in each component of the molten covering agent is FeO(very easily dissociated and participates in the reaction in the system).Secondly:The method of measuring the molten steel level by the two-electrode drop is feasible,the average measurement error is about 2 mm,and the maximum measurement error is within 5 mm.According to the analysis of the Gibbs free energy spectrum,the electrodes which reacted when the experiment was carried out with the two electrodes were graphite and tantalum,and the tungsten functions as a conduction circuit and does not participate in the reaction in the system.Thirdly:The graphite and tantalum electrodes have a shorter service life as the binary alkalinity increases.The graphite electrode can be repeatedly measured 6 times,and the tantalum electrode can be repeatedly measured 8 times.When the reaction end is consumed,it can be used for further reduction.Fourthly:The graphite electrode is greatly affected by the binary alkalinity.As the binary alkalinity increases,the voltage jump signal does not become obvious,and it is difficult to obtain the actual molten steel liquid level,while the tantalum electrode is not affected,and the voltage jumps.The signal is always obvious,which is more conducive to obtaining the actual molten steel level.The applied voltage method does not effectively alleviate the electromagnetic interference signal.Fifthly:The main factor causing the first voltage jump and the oxidation of the electrode tip is the galvanic effect.When the electrode enters the gas-slag interface,the electrode or its oxide reacts with the unstable slag-slag interface Fe2+ or Fe.The gain and loss electrons form a potential difference,and the second voltage jump is caused by the short circuit of the slag layer when the electrode enters the molten steel.Tantalum is expected to become the electrode material for continuous measurement of molten steel liquid level in the future.