Chapter 1314 - The Great Steel Campaign
Ji Wusheng kept watching the blast furnace, not saying a word from start to finish. This time he had decided to let the naturalized workers operate according to procedure on their own—he had already repeatedly discussed and rehearsed the specific smelting process with the workers responsible for the trial, and prepared contingency plans for various possible accident situations. This trial would show whether naturalized foremen like Zhao Youcai could more or less complete the entire workflow without transmigrator guidance and assistance.
Currently, both blast furnaces and the open-hearth furnace had naturalized foremen assigned by shift, but their work couldn't entirely put Ji Wusheng at ease. Every time iron or slag was tapped or composition was adjusted, he had to come and take a look, provide some guidance. This time he wanted to see whether his most outstanding furnace master could work completely independently of transmigrator oversight.
Seeing Zhao Youcai looking at him, he nodded and said loudly: "Zhao Youcai, from now on you're in command!"
A look of both nervousness and excitement flashed across Zhao Youcai's face. He responded loudly: "Understood!" Then he turned and began directing the furnace-front workers to their positions, awaiting the timing for formal charging. He himself stared intently at the flames inside the blast furnace.
"Begin first charge!" Zhao Youcai suddenly shouted. The charging workers on standby activated the equipment and fed a batch of charge into the blast furnace.
The charge for smelting ferrosilicon was mixed in ratios of silica sand, coke, pig iron, and quicklime at 5:3:1:2.5. Because this was the first batch of charge, the coke proportion was relatively high. After the fifth batch, the coke input proportion could be gradually reduced.
After charging was complete, Ji Wusheng quietly left the observation platform—the first tapping would be in 3 hours. He planned to return then to observe the actual tapping situation.
Three hours later, Ji Wusheng returned to the Special blast furnace front. Workers were tensely preparing for the first tap of molten iron. Without saying a word, he inspected the main trough and slag runner for foreign objects—this was the furnace's first tap. Theoretically, both troughs should be completely empty, but many times accidents happened precisely when things that "should have" occurred according to common sense didn't.
A slag ladle that should have been empty somehow had garbage mixed in—the moment blazing hot slag entered the ladle, it exploded outward like shrapnel, instantly killing two-thirds of a blast furnace work crew.
Such incidents—major accidents caused by tapping without proper preparation—had occurred more than once.
Ji Wusheng personally inspected every step according to standard work procedures: Was the tap-hole mud sleeve intact? Were all the flow gates on the iron runner and slag runner lowered? Were the trough spouts in good condition?...
"I've already sent someone to deliver the melt sample to the laboratory." Zhao Youcai had been busy directing workers in tapping preparations. Having just noticed Ji Wusheng's arrival, he hurried over to report. "Tapping preparations are complete. Waiting for melt sample test results."
Ji Wusheng nodded.
"I'm sure there won't be any problems this time."
"Whether there are problems or not depends on the lab results." Ji Wusheng was amused by his confident manner. "You can't tell accurately just by looking!"
"Yes." Zhao Youcai answered loudly. At that moment, a worker came rushing over, waving a slip of paper. Ji Wusheng didn't need to look to know this was the melt sample composition report the Heavy Industry Laboratory had just sent by wire telegraph.
Seeing Ji Wusheng present, the worker was about to hand the slip to him. Ji Wusheng shook his head, indicating he should give it directly to Zhao Youcai. Zhao Youcai took it and looked, then excitedly crumpled the slip into a ball. He turned and began shouting loudly, ordering workers to prepare to tap the first heat of ferrosilicon.
The casting molds coated with coke powder were already ready. Workers stood tensely by the tap hole with steel prybars, waiting for the order to open it.
Zhao Youcai pulled the alarm bell cord, and immediately bells clanged loudly.
"Tap!"
At his command, several workers used the overhead crane to move a hand-operated drill to the tap hole. Zhao Youcai first checked whether the mud sleeve had wet clay, and only when he confirmed the tap hole was dry did he nod to signal starting the drilling.
"Keep it steady!" Zhao Youcai shouted, carefully guiding the drill toward the mud sleeve. The tap hole was the hottest spot in the entire blast furnace workshop. The intense heat radiation made it hard for anyone to stand there for long, but Zhao Youcai still meticulously checked the drill bit's position. When drilling, the drill bit had to be aimed at the center of the tap-hole mud sleeve's funnel-shaped depression. Otherwise, if the mud sleeve was damaged or the tap hole drilled off-center, plugging would cause mud overflow or slag and iron to spray outside the trough.
"Start drilling!"
Workers began turning the drill. The drill bit slowly penetrated into the mud sleeve. Every few turns, the drill had to be withdrawn, and several workers immediately used blow pipes drawing air from the blast furnace to blow out the drilled tap-mud powder—to observe tap-hole conditions, see if drilling had reached the red spot, and measure tap-hole depth to determine how much more drilling was needed, avoiding burning out the drill bit and rod after drilling through.
"Slow down, don't rush!" Zhao Youcai stared fixedly at the drill and tap hole. Operating the drill was skilled work—movements had to be very steady to prevent excessive rod movement or jamming the bit. The drill operators had all been trained through over a hundred practice runs on simulated mud sleeves.
"Iron's flowing!" With a great shout from Zhao Youcai, the alarm bell rang again. As blazing furnace flames shot out, glowing molten iron surged from the tap hole, flowing down the main iron runner. The tap hole was instantly engulfed in smoke and steam. Molten iron flowed from the runner, pouring into casting molds coated with coke powder. Choking smoke and flames rose intermittently.
As the first tap of molten iron ended, Ji Wusheng quietly left the blast furnace workshop. From here on was normal production procedure—approximately every three hours there would be another tap. What concerned him now was the specific elemental content of each batch of ferrosilicon.
Back at the office, he found the melt sample composition report that had been delivered: silicon content 16.21%, roughly matching their estimated proportion. Before starting, he had estimated the first five batches' silicon content would be approximately 14-20%, rising to 17-30% as charging ratios changed thereafter.
"Starting with a good omen." Ji Wusheng relaxed. Looking at the overall composition report, this batch of ferrosilicon met the requirements for smelting silicon steel.
Smelting silicon steel was more difficult than ferrosilicon. The metallurgical sector's prepared method was to use a converter.
The metallurgical sector had four small converters brought from the old timeline. To be cautious, Ji Wusheng decided to use only the smallest one—a 1-ton class converter.
In the old timeline, the converter method for smelting silicon steel required oxygen blowing and argon gas protection, plus RH vacuum treatment and so forth. Ji Wusheng didn't have these conditions, so he had to settle for the air-blowing method.
Before smelting, the ferrosilicon first underwent preprocessing in a cupola—primarily further desulfurization to reduce the sulfur content of the molten iron entering the furnace to below 0.005%. The residual manganese and phosphorus elements in the pig iron weren't further processed. Although manganese had some negative effects on silicon steel's magnetic properties, manganese sulfide formed by manganese and sulfur could improve hot-rolling workability and prevent cracking during hot rolling. As for phosphorus, it itself had a function of improving iron loss, and also strengthened the adhesion of hot-rolled sheet surface oxide scale—after annealing it was less likely to produce oxide bonding white film. But too much phosphorus would also make the sheet brittle, so it had to be controlled below a certain content.
As for other elements, all had to be controlled to extremely low levels, especially nitrogen—nitrogen was harmful to silicon steel. In old-timeline silicon steel converter blowing processes, one approach was using pure oxygen, another was injecting argon as protective gas during smelting. But Lingao lacked both conditions and could only make do without.
The day after smelting ferrosilicon, Ji Wusheng personally took charge. Together with transmigrators from the industrial sector, they trial-smelted silicon steel. Because they now had spectrographic semi-quantitative analysis, for the first time Ji Wusheng basically knew the specific elemental composition and content of the raw materials about to be fed into the converter, allowing precise preparation of suitable materials. This was greatly beneficial for specialty steel smelting work.
After a day and night of struggle and multiple attempts adjusting materials and processes, they finally received good news from the Heavy Industry Laboratory's melt sample analysis: they had smelted silicon steel with 3% silicon content and carbon content below 0.04%. This steel was precisely the raw material for rolling silicon steel sheets used in electric motors.
The ideal silicon content for motor steel was 2.4-2.8%, but this steel still counted as qualified material. However, merely smelting suitable molten steel wasn't enough—Lingao's steel industry didn't have continuous casting and rolling processes, so molten steel had to first be cast into ingots before the hot-rolling mill could use it.
Steel ingot casting used protective slag, typically graphite powder. Graphite powder worked quite well but had obvious carburizing properties, sometimes adding 0.01-0.02%—very damaging for silicon steel with strict carbon content requirements. After consulting materials, several people finally decided to adopt carbonized rice husk with 40% carbon content—a process used by domestic steel plants in the 1970s. This material had a much lower ignition point than graphite powder; during casting, the carbon in the protective slag would burn off first, significantly reducing the carburization phenomenon. Moreover, this protective slag could substantially adsorb Al₂O₃ from the molten steel, greatly benefiting impurity reduction.
To produce this carbonized rice husk, Ji Wusheng had brought people to squat at Xiao Bailang's activated carbon production workshop to watch the kilns, experimenting dozens of times before managing to make carbonized rice husk with 40% carbon content.
After considerable effort, the Ma'ao Steel Complex finally cast qualified silicon steel ingots. Then, pressing on with their success, they trial-smelted silicon steel with 4.1% silicon content for transformer use. However, smelting silicon steel with the right content only completed half the work—the actual quality of silicon steel depended heavily on the subsequent cold-rolling or hot-rolling processes.
(End of Chapter)