Abstract: An apparatus and method for indexing the slag-metal interface level in a metallurgical container uses an insulating refractory brick having a plurality of embedded conductor wires. Distal ends of the conductor wires are exposed at know, fixed distances from the distal end of the stick and flush with the brick face. The proximal ends of the conductor wires protrude a predetermined distance from the proximal end of the brick. The brick is attached to the inner lining of the container at a known distance from the floor of the container. The proximal wire ends are joined by a suitable connector to a signal-transmission cable containing a matching number of individual conductors, which is connected to a multi-channel voltmeter. Output from the multi-channel voltmeter can be input to a multiple-channel PC-based signal interpretation instrument. During operation the voltage output of each sensor circuit is continuously monitored.

Abstract: A method and system for testing the accuracy of a thermocouple probe exposed to a medium having a temperature of between about 2200.degree. F. and 3400.degree. F. is provided that includes the step of measuring the rate of change of the temperature readings of the probe after a temperature of at least 2000.degree. F. is read, and comparing the measured rate of change with a standard rate of change obtained from a properly operating probe. Both the method and the system are advantageously capable of determining whether the temperature readings of a thermocouple in use in a steel production plant are accurate without the need for comparative readings from other thermocouple probes.

Abstract: Both an apparatus and method for measuring the depth of slag and molten metal contained in a tundish, ladle, electric furnace, or other vessel is provided. The apparatus includes a voltmeter for comparing the electrical potential of the steel, the slag-steel interface, and the air-slag interface to a ground potential, in combination with a probe member formed from a conductive material. The probe member has a proximal end that is electrically connected to the voltmeter, and a distal end movable between the vessel floor and one or the other of the interfaces. The apparatus further includes an articulated arm for positioning the distal end of the probe member in the vessel and across the molten metal so that it traverses at least one of the other two interfaces. The depth of the molten metal or slag is determined by noting differences in the electrical potential detected by the voltmeter while monitoring the vertical position of the distal end of the probe member in the vessel.

Abstract: Both an apparatus and method for detecting slag in a flow of molten metal conducted through a ladle shroud are provided. In the apparatus, first and second conductive pins are mounted beside one another in a wall of the ladle shroud, the first being in contact with the flow of molten metal, but electrically insulated from both the wall and from the second conductive pin, the second being in electrical contact both with the wall and with the flow of molten metal. A voltmeter is connected between the two conductive pins for detecting differences in the electrical potential between them as molten metal flows through the shroud. Abrupt changes in potential caused by the passage of a metal slag interface through the shroud indicate the presence of slag in the molten metal.

Abstract: A probe system for reliably monitoring a condition in a metallurgical process is provided which includes a probe having a circuit for generating a low DC voltage signal indicative of a condition in the metallurgical process, and an impedance monitoring circuit electrically connected to the probe circuit for passively and continuously measuring the impedance of the probe circuit to determine its reliability without disturbing its DC signal. The probe may be a slag detector, a thermocouple, a sulfur sensor, or an oxygen sensor of the type used in steel manufacturing processes. The impedance monitoring circuit includes an oscillator assembly and a known impedance that is serially connected to the probe circuit by means of coupling capacitors that prevent the conduction of potentially biasing DC currents through the probe circuit.

Abstract: A thermocouple assembly for sensing temperatures of molten metals in a metallurgical vessel, such as a tundish used in continuous steel casting, includes a double bore insulator containing the two noble metal alloy lead wires of the thermocouple. Platinum-rhodium alloys are preferred. The weld bead joining the ends of the leads or hot junction of the thermocouple is positioned within one of the bores of the insulator such that a lower purity alloy lead is exposed in the loop. The loop resides in a blind bore formed in the end of the double bore insulator and is enclosed in a containmemt zone by a refractory plug or foil disc closing off the end of the blind bore. The double bore insulator is received in an axial bore of a refractory sheath having a closed end adjacent the loop area of the thermocouple.