Hydrochloric acid pickling Introduction Pickling baths are used after of the hot rolling pro- cess, but also in many other fields of the metal- working industry. Thereby, pollutions are removed by previous production steps and the surface is prepared for the following process steps. At the same time, it comes to a passivation of the surface by the forma- tion of a protective coating. As a result, the surface is protected against further corrosion. Mainly pickling solutions that consist of mineral acids, such as hydro- chloric acid, are being used. After the pickling process, the steel can be formed or its surface can be refined for the use in the metal industry. Application Pickling removes impurities from the steel surface. However, the acid also attacks the iron oxide on the metal surface and dissolves a portion of it (for examp- le, iron (II)). It is therefore of great importance to pre- cisely control all process-relevant parameters, such as dwell time, bath temperature and bath composition. Only in this way, pickling bathes can be operated in an economic and resource-saving manner. Steel production is an ongoing process that runs both at night and on weekends. Frequently, the bath analysis is very complex and must be performed in a laboratory. The problem here is there is no qualified laboratory personnel available around the clock. The use of the LiquiSonic ® measurement system for pick- ling bath analytics opens new prospects at this point. The measuring system LiquiSonic ® 40 allows the parallel detection of two physical quantities, such as sonic velocity and conductivity, the determination of the HCl concentration in the pickling bath as well as
Transcript
Hydrochloric acid picklingIntroductionPickling baths are used after of the hot rolling pro-cess, but also in many other fields of the metal-working industry. Thereby, pollutions are removed by previous production steps and the surface is prepared for the following process steps. At the same time, it comes to a passivation of the surface by the forma-tion of a protective coating. As a result, the surface is protected against further corrosion. Mainly pickling solutions that consist of mineral acids, such as hydro-chloric acid, are being used.
After the pickling process, the steel can be formed or its surface can be refined for the use in the metal industry.
ApplicationPickling removes impurities from the steel surface. However, the acid also attacks the iron oxide on the metal surface and dissolves a portion of it (for examp-le, iron (II)). It is therefore of great importance to pre-cisely control all process-relevant parameters, such as dwell time, bath temperature and bath composition. Only in this way, pickling bathes can be operated in an economic and resource-saving manner.
Steel production is an ongoing process that runs both at night and on weekends. Frequently, the bath analysis is very complex and must be performed in a laboratory. The problem here is there is no qualified laboratory personnel available around the clock. The use of the LiquiSonic® measurement system for pick-ling bath analytics opens new prospects at this point.
The measuring system LiquiSonic® 40 allows the parallel detection of two physical quantities, such as sonic velocity and conductivity, the determination of the HCl concentration in the pickling bath as well as
the iron (II) content. This leads to the elimination of expensive laboratory analysis.The installation of the inline LiquiSonic® sensors enables the user to moni-tor process concentrations around the clock and to provide an exact real time analysis. In this respect, it is possible to immediately react to fluctuations in the acid concentration.
For the use in pickling bath, LiquiSonic® 40 is stan-dardly equipped with a HALAR coated flange type sensor and a PFA or PEEK coated conductivity sen-sor, which have a chemical resistance to a variety of substances. The flange type sensor continues to have a highly efficient ultrasonic ceramic, which guarantees a measurement even when there is high gas content in the liquid.
Customer benefitsLiquiSonic® allows cost savings through the reduction of hydrochloric acid consumption (30 m3 plant: 7,5 m3/h acid consumption):
· 30 % corresponds to 60.000 € per year
· 20 % corresponds to 40.000 € per year
· 10 % corresponds to 20.000 € per year
LiquiSonic® enables a reduction of labor costs through the elimination of manual process steps:
InstallationThe LiquiSonic® 40 analyzer is installed into the trans-port pipelines DN80 or the bypass from the pickling bath. Further installations are either in the transport line of the rinsing bath or in the fresh acid feed.
Additional option: Installation adapter for LiquiSonic® DN80 flange type sensor and conductivity sensor
The installation of the LiquiSonic® flange type sensor DN80 and the corresponding conductivity sensor in a piping system DN80 is simplified through the use of the installation adapter DN80. The total length of the measuring distance can be shortened by the adapter, to 0.70 m.
concentration range of free HCl: 35 g/l to 125 g/l; 180 g/l to 250 g/lconcentration range of Fe (II): 35 g/l to 160 g/ltemperature range: 60 °C to 95 °C
LiquiSonic® controller and Halar coated flange type sensor Installation adapter for LiquiSonic® sensors
