With Iran’s growing emphasis on environmental protection and efficient resource utilization, coupled with industry challenges such as fluctuating international energy prices and tight molten iron supply, local steel enterprises are in urgent need of breaking development bottlenecks through technological upgrading: improving the proportion of scrap steel consumption and reducing reliance on molten iron while ensuring normal operations and stable employee income.
As a professional provider of refractory material solutions, Highland Refractory customized ladle covering supporting refractories and technical schemes according to customer needs, helping a well-known Iranian steel enterprise complete the commissioning, installation and application of ladle covering facilities.
Relying on the thermal insulation advantages of high-performance refractories and scientific process adaptation design, the project successfully reduced tapping temperature, significantly increased scrap steel charging capacity, and created considerable economic and production benefits for the customer.Custom Ladle Cover Refractories for Iran Steel
01 Core Significance of Ladle Covering and Refractories for Steelmaking Production
The ladle is a core link connecting converter finished products and continuous casting raw materials. During the entire process of hoisting and pouring, heat loss caused by thermal radiation is a major energy waste point for steel enterprises. For steel mills, every degree of molten steel temperature is directly related to production efficiency. Therefore, reducing heat loss during transportation has become a key direction to improve production efficiency.
Mature steel enterprises have mature capabilities to control heat loss from ladle lining heat conduction, but thermal radiation loss caused by the contact between molten steel surface and air remains a technical difficulty. Before May 2018, the Iranian steel enterprise reduced heat loss by adding covering agents, but the effect was limited. Based on its technical accumulation in the field of refractories, Highland Refractory proposed a combined solution of “ladle covering + high-performance thermal insulation refractories” — the ladle cover adopts high-temperature resistant and low thermal conductivity refractory composite materials customized by Highland Refractory, combined with scientific covering process design, to block thermal radiation transmission from the source and achieve a significant reduction in heat loss.
02 Project Cooperation Background: Equipment and Process Overview
The cooperative partner, a well-known Iranian steel enterprise, was established in 2006. Its steelmaking system is equipped with 2 oxygen top-bottom combined blowing converters with a nominal capacity of 120t and 2 8-strand continuous casting machines, with a designed annual steel output of 2.6 million tons. It mainly produces carbon steel, low alloy steel and general steel rolled products. The process route is as follows:
Converter hot metal ladle → Hot metal slag skimming → Converter → LF refining furnace → Continuous casting machine → Steel rolling production line
The enterprise’s converters adopt the top-bottom combined blowing process, the LF furnace smelting cycle needs to be efficiently matched with the converter production rhythm, and the continuous casting link controls oxide formation through protective casting technology. In the early stage of the project, Highland Refractory conducted in-depth research on the characteristics of the customer’s production process, and customized highly adaptable ladle cover refractory formulas and covering device supporting schemes according to core parameters such as ladle size, operating temperature and turnover frequency, ensuring seamless connection between the technology and the existing production system.
03 Highland Refractory Ladle Covering Supporting Scheme: Process Equipment and Operation Characteristics
In this project, Highland Refractory not only provided core refractories but also collaborated with the customer to complete the overall optimization design of the ladle covering device: based on on-site production reality and available spare parts, the traditional hydraulic transmission was changed to mechanical transmission, and the hook and unhook of the ladle cover were realized by the operation of the ladle car. The core equipment includes the ladle cover (adopting refractories customized by Gaoyuan Refractories), gantry, hoisting mechanism, etc. Among them, the refractory performance of the ladle cover is the core to ensure the thermal insulation effect.
3.1 Core Advantages of Ladle Cover Refractories
The ladle cover refractories customized by Highland Refractory for this project are made of high-aluminum composite raw materials through special molding and sintering processes, with three core advantages: ① Excellent high-temperature resistance, capable of withstanding molten steel radiation temperature above 1600℃ for a long time without cracking or falling off risks; ② Low thermal conductivity, outstanding thermal insulation effect, which can effectively block molten steel thermal radiation loss; ③ High mechanical strength, adapting to the impact and wear of complex operating scenarios such as ladle hoisting and slag dumping, with a long service life.
3.2 Ladle Cover Uncovering and Covering Operation Processes
3.2.1 Uncovering Process
The uncovering operation is performed when adding flux before tapping: the overhead crane lifts the ladle equipped with Highland Refractory customized refractory cover to the tapping car, and the tapping car drives to the designated position under the covering equipment; the operator first checks the integrity of the hoisting mechanism, hooks and other components as well as the refractory layer of the cover, and closes the switch to supply power after confirmation; moves the ladle to align under the hoisting mechanism; lifts the cover through the process of lowering the hook, moving forward and lifting the hook (ensuring that the 4 lifting lugs are fully stressed); after the ladle cover is lifted, the ladle enters under the furnace with the tapping car to prepare for tapping, and the uncovering is completed.
3.2.2 Covering Process
After tapping and post-furnace treatment, the tapping car carrying the full ladle drives to the designated position under the covering equipment; adjusts the ladle position to align with the cover, presses the lowering button to embed the cover groove into the ladle lugs to ensure tight covering; then separates the cover from the mechanism by retracting the hook and lifting, and drives the tapping car away — the sealing design and refractory material of the cover customized by Highland Refractory can minimize heat loss during subsequent transportation.
3.2.3 Slag Dumping Process
When dumping slag from the empty ladle under the continuous casting machine, the ladle inclination angle shall not exceed 40 degrees to prevent failure to reset due to excessive inclination; the separation of the ladle cover and the ladle is realized by the force of the rear lifting lugs of the cover and gravity; during slag dumping, slowly lift the auxiliary hook to avoid the refractory layer of the cover being impacted by the rapid flow of slag; after the slag in the ladle is completely dumped, the ladle returns to the hot repair position, and can enter the next cycle after checking that the refractory layer of the cover is intact.
04 Application Effect Analysis: Core Value Embodiment of Highland Refractory Scheme
The project was officially put into use in May 2018 and completed process optimization in June-July. To accurately verify the application effect of Highland Refractory ladle covering refractories, statistical analysis was conducted on the temperature data and scrap steel charging capacity of carbon steel and low alloy steel from April to August, and the results are as follows:
Table 1 Low Alloy Steel Temperature Change Statistics
Month
Tapping Temperature (℃)
Ladle Temperature (℃)
Temperature at Continuous Casting Platform (℃)
April
1678
1609
1600
May
1675
1604
1593
June
1673
1602
1593
July
1670
1597
1603
August
1668
1597
1592
Table 2 Carbon Steel Temperature Change Statistics
Month
Tapping Temperature (℃)
Ladle Temperature (℃)
Temperature at Continuous Casting Platform (℃)
April
1664
1623
1617
May
1661
1620
1615
June
1656
1616
1612
July
1653
1617
1609
August
1654
1608
1602
From the data and practical application effects, Highland Refractory ladle covering refractory scheme has achieved multiple value breakthroughs:
(1) Significantly reduce temperature loss and create direct economic benefits: For low alloy steel, the tapping temperature decreased by 10℃, the ladle temperature decreased by 12℃, and the temperature at the continuous casting platform decreased by 8℃; for carbon steel, the tapping temperature decreased by 10℃, the ladle temperature decreased by 15℃, and the temperature at the continuous casting platform decreased by 15℃. The average temperature drop of converter molten steel exceeded 10℃. It is estimated that each 1℃ reduction in molten steel temperature can create about 1.5 US dollars in benefits. Based on an annual steel output of 2.4 million tons, the customer gains an additional 36 million US dollars in benefits every year, which is mainly due to the low thermal conductivity and high thermal insulation performance of our refractories.
(2) Increase scrap steel charging capacity and alleviate reliance on molten iron: The average scrap steel charging capacity per furnace was 26.19 tons in April and increased to 35.35 tons in August, an increase of 9.1 tons per furnace. Against the background of tight molten iron supply, the space for adding scrap steel was released by reducing temperature loss, indirectly increasing production capacity.
(3) Optimize ladle turnover conditions: The temperature of the empty ladle under continuous casting increased from 1020℃ to 1300℃, reducing heat loss during ladle turnover, lowering subsequent heating energy consumption, extending the service life of the ladle lining, and reducing maintenance costs.
(4) Ensure molten steel quality: The combination of the ladle covering design and the sealing performance of refractories effectively reduces the oxygen absorption of molten steel during transportation, avoids oxide formation, and provides strong support for the customer to improve product quality.
As a professional provider of refractory material solutions, Highland Refractory cooperation with a well-known Iranian steel enterprise successfully addressed the customer’s core needs of “cost reduction, efficiency improvement and reducing reliance on molten iron” through customized ladle covering refractories and process adaptation schemes. Project practice has proved that:
(1) The combination of our high-performance refractories and ladle covering technology can effectively block thermal radiation loss, reduce tapping temperature by more than 10℃, and save a lot of energy costs for enterprises;
(2) The technical scheme significantly increases scrap steel charging capacity, helping customers stabilize production capacity and enhance market competitiveness against the background of tight molten iron supply in the industry;
(3) The scheme is fully compatible with the customer’s existing production process, has no negative impact on continuous casting ladle lowering and ladle turnover, and achieves seamless connection between technological upgrading and production rhythm;
(4) The excellent performance and sealing design of refractories provide guarantee for the improvement of molten steel quality, further expanding the market application space of the customer’s products.
In the future, Highland Refractorywill continue to focus on the energy-saving and consumption-reducing needs of the steel industry. With its technical accumulation and innovation capabilities in the field of refractories, it will provide more efficient and reliable customized refractory material solutions for global steel enterprises, and work with customers to achieve green, low-carbon and high-quality development.
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