Regardless of the specific configuration, secondary lance systems share a common feature: they employ mechanized automation to perform tasks such as probe installation, insertion into the furnace for monitoring, probe withdrawal, and probe removal. Based on an analysis of typical secondary lance installations at steel plants both domestically and internationally, and classified according to the overall equipment layout, these systems can be broadly categorized into the following five types:
1. Opposite-side fixed arrangement;
2. A counter-rotating arrangement on the side opposite to the frame’s rotation during operation;
3. A counter-rotating arrangement in which the frame remains stationary during operation;
4. A rotary arrangement on the same side, with the frame remaining stationary during operation;
5. Lateral offset arrangement on the opposite side.
In the aforementioned categories, the terms “same side” and “opposite side” refer to the relative positioning of the oxygen lance with respect to the side of the converter shop where it is installed. When the secondary lance and the oxygen lance are both located on the same side of the converter shop, they are considered to be on the same side; otherwise, they are on opposite sides. Each arrangement is suited to specific steelmaking processes and plant configurations, each possessing its own distinct characteristics.
1 Opposite-side fixed arrangement
The counter‑side fixed lance arrangement refers to a configuration in which the lance rail is mounted on the side of the oxygen lance opposite the converter. Baosteel’s Stainless Steel Division employs this approach for its 120‑t AOD furnace. During operation, the probe is installed directly at the charging position, followed by in‑furnace measurements; after lifting the lance and tapping out the melt, the probe is removed again at the charging position.
The main features of this arrangement are:
(1) The secondary lance has a short operating cycle (typically within 100 seconds).
The advantage of a short cycle is that, should this measurement fail due to probe‑related issues or signal disturbances, the faster the response time for a follow‑up measurement, the lesser the impact on molten steel quality and the overall smelting cycle. Furthermore, given that the interval between intermediate and endpoint measurements with the secondary lance is typically only about 3 minutes, an excessively long operating cycle for the secondary lance would directly compromise the smelting schedule.
(2) The lifting stroke of the secondary lance is relatively large.
Since the secondary lance requires probe installation and removal at the furnace entry position, regardless of the equipment used for these operations, sufficient vertical clearance must be maintained between the top of the equipment above the opening in the vaporization flue and the bottom of the probe connector to facilitate probe handling. Consequently, compared with a remote‑location probe‑removal configuration, the lifting stroke of a fixed‑type secondary lance is approximately 2.5 to 3 meters longer.
The side‑mounted secondary lance has consistently occupied a portion of the space above the converter; it is suitable for the following applications:
The refractory lining of the converter is installed off‑line. For converters used to smelt stainless steel, which experience rapid refractory consumption and have short campaign durations, the conventional approach to minimize production disruptions during maintenance is to replace the entire shell. The in‑service old shell is removed and replaced with a newly lined and dried shell, allowing immediate resumption of production. Meanwhile, the old shell is taken offline for dismantling, relining, and drying, ensuring that main‑line operations remain unaffected.
A converter employing the bottom‑removal repair method. In this approach, the furnace hearth is removable; during maintenance, the hearth is dismantled, and refractory materials are conveyed and laid from the bottom of the furnace shell using equipment such as a repair carriage.
A converter employing a simple overhauling method. This repair approach is used on small and medium-sized converters with limited automation. During maintenance, temporary scaffolding is erected manually to carry out refractory masonry work.
This applies to workshops where single‑ or double‑turret oxygen converters are arranged adjacently within the same span. During operation, the oxygen lance is kept in place on the line, and together with the auxiliary lance it obstructs the transport corridor across the converter span, thereby limiting the available routing for moving spare oxygen lances and other maintenance activities. When double‑turret converters are arranged side by side, to prevent mutual interference during production and maintenance, dedicated storage areas for spare oxygen lances and associated hoses must be provided on both sides of the converter span.
2 Opposite-side rotary arrangement of the frame during operation
In this arrangement, the framework of the secondary lance lifting track is positioned on the opposite side of the oxygen lance and can rotate about its pivot point. During operation, the secondary lance first installs the probe at the standby position, then rotates to the furnace‑entry position to perform in‑furnace measurements. After raising the lance, it returns from the furnace‑entry position to the standby position to remove the probe.
The characteristics of this arrangement are:
(1) The work cycle is relatively long.
Due to the additional two cycles of rotation and positioning, the cycle time for this layout type ranges from 120 to 160 seconds.
(2) The secondary lance has a short lifting stroke.
The upper limit position of the secondary lance only requires that the bottom of the probe extend above the equipment located above the secondary lance opening in the vaporization flue—such as the nitrogen seal, sealing door, and slag scraper. Due to its short stroke, the overall height of the secondary lance system is relatively low, placing modest demands on the overhead clearance of the converter shop building.
Because the frame is rotatable, it offers greater flexibility and adaptability, making it suitable for the following applications:
Two or more oxygen‑converter workshops arranged side by side under the same span. During oxygen‑lance replacement, hoisting operations, or equipment maintenance, the secondary lance is positioned at the standby location, thereby freeing up the transport corridor.
The converter employs a highly mechanized overhead repair‑tower method. During maintenance, both the main oxygen lance and the auxiliary lance remain in their standby positions; the flue carriage is retracted, the repair carriage is moved directly beneath the converter, and the repair tower is hoisted onto the repair carriage and securely fastened.
Due to factors such as production capacity, modern steel plants typically arrange their converters in pairs or in multiple parallel configurations. Converter shells are generally of a non‑removable design, and refractory repairs are usually carried out on‑line using repair towers. Consequently, secondary lance systems configured in this manner have become a standard feature in contemporary steelmaking facilities, exemplified by Japan’s JFE Fukuyama Works and Kōbe Steel Works, ThyssenKrupp’s plant in Germany, Voestalpine’s Linz Works, and more than 98% of domestic steel mills equipped with secondary lances.
3 Counter-rotating arrangement with the frame stationary during operation
This configuration is consistent with the side‑rotating arrangement of the equipment; the key differences are as follows: First, the probe handling unit is mounted not on the shop floor platform but on a small platform carried by a mobile hood trolley. During operation, probe installation, removal, and insertion into the furnace all occur at the same location, resulting in a short cycle time—typically under 100 seconds. The secondary lance and its frame remain stationary during normal operation, rotating only when performing furnace maintenance or clearing the transport passage. Second, the lifting stroke is relatively large, and the lance body is longer.
This configuration effectively combines the advantages of the two aforementioned arrangements, featuring a short operating cycle and allowing the converter‑side transport corridor to remain unobstructed. However, its drawback is the relatively high overall height of the secondary lance equipment. If this height compromises the clearance within the converter‑side building, the issue can be addressed by adopting movable guide rollers for the lance body, thereby reducing both the track elevation and the lance length.
This configuration has been implemented at the Wakayama Steel Works in Japan and on the 150‑t carbon steel converter at Baosteel’s Stainless Steel Division.
4 Rotational arrangement on the same side, with the frame remaining stationary during operation.
In this arrangement, the secondary lance rotary frame and its rotary support are positioned on the same side as the oxygen lance. During operation, the rotary frame remains stationary, and both the installation/removal of the probe and its insertion into the furnace are carried out at the same location. Compared with the opposite-side rotary configuration, in addition to inheriting all its advantages, the key distinguishing feature is that the same-side layout leaves an unobstructed access corridor along the converter span, ensuring that the replacement and maintenance hoisting of standby oxygen lances for other converters do not interfere with production at all. The frame itself is designed as a rotary type solely to provide clearance for the refractory‑lining tower during refractory masonry work on the converter.
Because it is arranged on the same side as the oxygen lance, its rotational support point can only be located above the oxygen‑lance equipment. When the rotating frame is in its working position, the bottom of the lifting‑track frame is fixed to the platform to ensure sufficient rigidity.
In addition, the selection of the secondary lance insertion point is influenced by factors such as the furnace type, the converter’s nominal capacity, the arrangement of the bottom-blowing tuyeres, the size of the converter mouth, and the external dimensions of the secondary‑lance equipment. Typically, the distance between the secondary‑lance insertion position and the center of the converter (the oxygen‑lance insertion point) ranges from 900 to 1,400 mm. When the secondary lance is arranged on the same side as the oxygen lance, the available space for the secondary‑lance equipment becomes significantly constrained; consequently, components such as the lance body and the lifting‑rail frame are designed to be relatively more compact and streamlined. Due to these spatial limitations, designing a co‑side‑arranged secondary lance is comparatively challenging, and to date, only Baosteel in China has adopted this configuration.
5 Lateral offset arrangement on the opposite side
The secondary lance is arranged on the opposite side of the oxygen lance, with its lifting track integrated into the upper traversing carriage. During operation, the secondary lance is fitted with a probe at the standby position, then moves laterally on the traversing frame to the furnace entry position for measurement; upon completion, the lance is raised and retracted, and the carriage returns to the standby position to remove the probe. Its operating cycle and lifting stroke are comparable to those of the opposing rotary configuration, where the frame rotates on the opposite side. The adoption of a lateral‑travel arrangement is primarily dictated by the longitudinal dimensions of the converter span. In many steel plants that have already commenced production but lack secondary‑lance facilities—often because no dedicated space was allocated for such a system during initial construction—it becomes impractical to retrofit a conventional rotary layout, as there simply is not sufficient room for installation. The lateral‑travel configuration effectively addresses this challenge.
The key features of the laterally offset secondary lance system are as follows: it has a short lifting stroke, a cycle time of approximately 120 to 150 seconds, and a compact footprint. It is suitable for converters employing various furnace‑relining methods and can be installed in plants with very narrow converter bays, making it particularly well suited for retrofitting existing steelworks.
The side‑shift type is employed in the No. 23 converter at Holland’s Hoogovens Steel Company and in the converters at China’s Xinjiang Bayi Steel Second Steelmaking Plant.
The five sub‑gun configurations outlined above essentially encompass the existing range of overall sub‑gun arrangements, each with its own advantages and disadvantages as well as specific application scenarios. The ultimate goal is to select the most appropriate configuration for each set of operating conditions.