Container for molten metal, use of the container and method for determining an interface

Abstract

A container for molten metal is provided with a temperature measuring device arranged in an opening of a container wall. The temperature measuring device has a protective sheath, which projects into the container and which is closed at its end arranged in the container. A temperature measuring element is arranged in an opening of the protective sheath. The protective sheath is composed of a mixture of a heat-resistant metal oxide and graphite, and the closed end is spaced at least 50 mm from the container wall.

1 . A container for molten metal comprising a temperature measuring device arranged in an opening of the container wall, wherein the temperature measuring device has a protective sheath, which projects into the container and which is closed on its end arranged in the container, and a temperature measuring element arranged in an opening of the protective sheath, wherein the protective sheath comprises a mixture of a heat-resistant metal oxide and graphite, and wherein the closed end is spaced at least 50 mm from the container wall.  
     
     
         2 . The container according to  claim 1 , wherein the closed end is spaced approximately 75 to 200 mm from the container wall.  
     
     
         3 . The container according to  claim 1 , wherein the temperature measuring device is arranged in a part of the container wall forming a floor of the container.  
     
     
         4 . The container according to  claim 1 , wherein the protective sheath consists essentially of aluminum oxide.  
     
     
         5 . The container according to  claim 1 , wherein the protective sheath consists essentially of aluminum oxide with a portion of approximately 20 to approximately 80 wt. % and graphite with a portion of approximately 5 to approximately 60 wt. %.  
     
     
         6 . The container according to  claim 1 , wherein a protective tube is arranged in the protective sheath.  
     
     
         7 . The container according to  claim 6 , wherein the protective tube comprises aluminum oxide and surrounds the temperature measuring element,  
     
     
         8 . The container according to  claim 1 , wherein the protective sheath has at least on one part of its length an outer conical form with a diameter becoming smaller toward an interior of the container.  
     
     
         9 . The container according to  claim 1 , wherein the temperature measuring element is a thermocouple.  
     
     
         10 . The container according to  claim 1 , further comprising a sensor projecting into the interior of the container for determining a change in material, wherein the sensor is arranged on the protective sheath.  
     
     
         11 . The container according to  claim 10 , wherein the sensor is at least one selected from the group consisting of an electrochemical sensor, an electromagnetic sensor, an optical sensor, and a sensor for detecting at least one of an electrical voltage, an electrical current and an electrical resistance.  
     
     
         12 . The container according to  claim 1 , further comprising a bushing made of refractory material and having a conical shape with a diameter becoming smaller toward an interior of the container, wherein the bushing is arranged in the opening of the container wall between the container wall and the protective sheath.  
     
     
         13 . The container according to  claim 12 , wherein the bushing comprises mullite  
     
     
         14 . The container according to  claim 1 , wherein the container is a foundry ladle for molten steel.  
     
     
         15 . A method for determining an interface between two materials arranged one above another in a container, the method comprising arranging within the lower material a sensor for determining a change in material, and measuring a measurement signal of the sensor during pouring or outflow of the material from the container, such that a change in signal is established when the sensor contacts the interface between the materials.  
     
     
         16 . The method according to  claim 15 , wherein the interface is between a slag layer and an underlying molten steel.  
     
     
         17 . The method according to  claim 15 , wherein the sensor is at least one selected from the group consisting of an electrochemical sensor, an electromagnetic sensor, an optical sensor, and a sensor for detecting at least one of an electrical voltage, an electrical current and an electrical resistance.  
     
     
         18 . The method according to  claim 15 , wherein the change in signal is associated with a distance of the interface from a floor of the container.  
     
     
         19 . The method according to  claim 15 , wherein the pouring or outflow of the material is terminated when the signal changes.