Ji Wusheng had been looking at the blast furnace without saying a word. This time he decided to let the naturalized workers do it according to the process - he had discussed and rehearsed the specific smelting process many times with the workers in charge of the trial, so that was it. Plans have been made for various accident situations that may occur. [Read full text] In this trial, he wanted to see if a naturalized migrant foreman like Zhao Youcai could roughly complete the entire work process without the guidance and assistance of the elders.
Now two blast furnaces and one open-hearth furnace are equipped with naturalized foremans according to shifts, but their work does not completely reassure Ji Wusheng. Every time the iron is tapped, slag is removed or the ingredients are adjusted, he has to come over to take a look and give guidance. one time. This time he wanted to see if his best furnace manager could completely break away from the guidance of the elders.
Seeing Zhao Youcai looking at him, he nodded and said loudly: "Zhao Youcai, you will be in charge now!"
A look of nervousness and excitement suddenly appeared on Zhao Youcai's face, and he responded loudly: "Understood!" He turned around and began to direct the workers in front of the furnace to get into their positions, waiting for the opportunity to officially load materials. He himself stared closely at the flames in the blast furnace,
"Start the first feeding!" Zhao Youcai suddenly shouted. The feeding workers on standby started the equipment and put a batch of materials into the blast furnace.
The materials for making ferrosilicon are mixed according to the ratio of silica sand, coke, pig iron and quicklime in the ratio of 5:3:1:2.5. Because it is the first batch of materials, the proportion of coke is relatively high. After the fifth batch of materials is thrown in, the proportion of coke input can be gradually reduced.
After adding the material, Ji Wusheng quietly left the observation platform - the first iron tapping would be in 3 hours, and he planned to come back at that time to see the actual iron tapping.
Three hours later, Ji Wusheng returned to the special blast furnace. Workers are nervously preparing for the first tap of molten iron. Ji Wusheng said nothing and checked whether there were any foreign objects in the main ditch and the lower slag ditch - this was the first time the special blast furnace was tapping iron. Theoretically, there should be nothing in the two ditches. However, accidents often occur. Things that “should” don’t happen as they should.
Garbage was mixed into the iron slag tank that was supposed to be free of foreign objects. As soon as the hot iron slag entered the tank, it exploded like shrapnel, killing two-thirds of the blast furnace working class in an instant. .
There have been more than one major accidents caused by tapping the iron without being prepared.
Ji Wusheng followed standard working procedures and personally inspected every link: whether the mud sleeve of the taphole was intact, whether the gates of the iron ditch and the lower slag ditch were lowered, whether the flow nozzle of the slag-iron ditch was intact...
"I have sent someone to send melt samples to the laboratory." Zhao Youcai was busy instructing the workers to make iron preparations. He just saw Ji Wusheng coming and hurried over to report, "The iron preparations are ready and we are waiting for the test results of the melt samples. .”
Ji Wusheng nodded.
"I think there will definitely be no problem this time."
"Whether there is any problem depends on the results of the laboratory." Ji Wusheng was amused by his confident energy, "You can't tell accurately with your eyes alone!"
"Yes." Zhao Youcai responded loudly. At this time, a worker hurried over, waving a piece of paper in his hand. Without looking at it, Ji Wusheng knew that this was the melting sample test result that had just been sent by wired telegram from the Heavy Industry Laboratory.
The worker saw Ji Wusheng present and was about to hand the order to him. Ji Wusheng shook his head and motioned to hand it over directly to Zhao Youcai. Zhao Youcai took it and looked at it. He clenched the note into a ball excitedly. He turned around and shouted loudly, asking the workers to prepare to release the first furnace of molten ferrosilicon.
The casting molds coated with coke powder are ready, and the workers, holding steel drills, are nervously waiting for the order to open the taphole.
Zhao Youcai pulled the cord of the warning bell, and the bell rang loudly.
"Take out the iron!"
He gave the order, and several workers used a crane to move a hand-operated drill to the taphole. Zhao Youcai first checked whether the mud sleeve of the taphole was wet mud. After confirming that the taphole was dry, he nodded. Start drilling.
"Move steadily!" Zhao Youcai shouted, carefully holding the drilling rig close to the mud casing. The temperature at the taphole was the highest in the entire blast furnace workshop. The strong thermal radiation made it difficult for people to stand there for a long time, but Zhao Youcai Still carefully check the position of the drill bit. When drilling, the drill bit must be aligned with the center of the funnel-shaped deep pocket of the tappet sleeve. Otherwise, the taphole sleeve will be damaged or the taphole will be drilled sideways. When the taphole is blocked, mud will erupt or slag and iron will be ejected out of the trench.
"Drill!"
The workers began to shake the drilling rig, and the drill bit slowly drilled into the mud jacket. Every time it drilled a few circles, the drilling rig had to withdraw. Several workers immediately used the blow pipe drawn from the blast furnace to blow the revolving mouth and blow out the drilled mud. powder. In order to observe the condition of the tap hole, whether the red dot is drilled, and measure the depth of the tap hole to determine how much more drilling is required to avoid burning the drill bit and drill pipe after drilling leakage.
"Slow down, don't rush!" Zhao Youcai stared closely at the drilling rig and the iron mouth. Starting a drilling rig is a technical job, and the movement must be very stable to prevent the drill pipe from swinging too much or the drill bit getting stuck. Drilling rig workers have been trained hundreds of times on simulated mud jackets.
"The iron is being tapped!" As Zhao Youcai shouted, the alarm bell rang again. As the hot furnace flames spurted out, red molten iron surged out of the tap hole and sloped down along the main iron trench. The taphole was suddenly shrouded in smoke. Molten iron flows from the iron trench and is poured into the mold coated with coke powder. Choking smoke and flames rose from time to time.
With the end of the first molten iron tapping, Ji Wusheng quietly left the blast furnace workshop. The following is the normal production process. Iron will be produced approximately every three hours. What he needs to care about is the specific element content of each batch of ferrosilicon.
There was a composition report of the melted sample sent to the office: the silicon content was 16.21%, which was roughly the same as the proportion they estimated. Before starting the refining, he estimated that the silicon content of the first five batches would be between 14 and 20%. As the feed ratio changes, the silicon content will rise to 17-30%.
"It's a good start." Ji Wusheng breathed a sigh of relief and looked at the overall composition report. This batch of ferrosilicon met the needs of silicon steel making.
The difficulty of making silicon steel is greater than that of ferrosilicon. The smelting method prepared by the metallurgical port is to smelt silicon steel using a converter.
There are 4 small converters brought from the old time and space at the Metallurgical Port. To be cautious, Ji Wusheng decided to only use the smallest one, a 1-ton converter.
In the old days, ferrosilicon smelting by the air-space converter method required oxygen blowing and argon gas protection, as well as rh vacuum treatment and so on. Ji Wusheng didn't have this condition, so he had to settle for the air blowing method.
Before starting smelting, ferrosilicon is first pre-treated in the iron furnace, and first further desulfurized, so that the sulfur content of the molten iron entering the furnace is less than 0.005. As for the remaining manganese and phosphorus elements in the pig iron, they will no longer be processed. Although manganese element has certain side effects on the magnetism of silicon steel, manganese sulfide synthesized from manganese element and sulfur element can improve the processability of hot rolling and avoid cracking during hot rolling. As for the phosphorus element itself, it has the effect of improving iron loss and strengthening the adhesion of the iron oxide scale on the surface of the hot-rolled plate. It is not easy to produce an oxidized adhesive white film after annealing. However, if the phosphorus element is too high, it will also make the board brittle, so the content must be controlled under a certain level.
As for various other elements, we must try to control them at extremely low levels, especially nitrogen-nitrogen is very harmful to silicon steel. In the old silicon steel converter blowing process, pure oxygen was used, and argon was injected as a protective gas during steelmaking. However, there are no two conditions for Lingao, so he can only live without it.
The day after the ferrosilicon was smelted, Ji Wusheng went to battle in person and cooperated with a group of industry veterans to test the silicon steel. Thanks to the spectroscopy method that can conduct semi-quantitative analysis of elements, Ji Wusheng roughly grasped the specific element composition and content of the raw materials to be put into the converter for the first time during the material preparation, and could accurately prepare suitable raw materials. This is of great benefit to the work of refining special steel.
After struggling day and night, trying many times, and adjusting ingredients and processes, they finally got good news from melt sample analysis in the heavy industry laboratory. They refined silicon steel with a silicon content of 3% and a carbon content of less than 0.04%. This steel is the raw material used to roll the silicon steel sheets used in motors.
The ideal silicon content of motor steel is 2.4 to 2.8%, but this kind of steel is considered a qualified material. However, it is not enough to just make suitable molten steel. Lingao's steel industry does not have continuous casting and rolling processes. The molten steel must first be cast into steel ingots before it can be used by the hot rolling mill.
Casting steel ingots use a protective slag process, generally using graphite powder. Graphite powder has a better effect, but it has obvious carburizing properties, sometimes increasing to 0.01 to 0.02%, which is very difficult for silicon steel that has strict requirements on carbon content. Said there was a lot of damage. After several people reviewed the information, they finally decided to use the process of carbonized chaff containing 40% carbon that was used by domestic steel plants in the 1970s. The ignition point of this material is much lower than that of graphite powder. During casting, the carbon in the mold powder is burned first, and the carburization phenomenon is significantly reduced. Moreover, this kind of mold powder can also greatly absorb al2o3 in the molten steel, which is beneficial to reducing the temperature in the molten steel. The impurities have great benefits.
In order to produce this kind of carbonized chaff, Ji Wusheng took people to Xiao Bailang's activated carbon workshop to inspect the kiln. After dozens of experiments, he finally made a carbonized chaff with a carbon content of 40%.
After some hard work, Ma Niao Iron and Steel Consortium finally cast qualified silicon steel ingots. Then, they continued their efforts and tested silicon steel with a silicon content of 4.1% for transformers. However, refining silicon steel with the appropriate content is only half the work - the specific quality of silicon steel depends largely on the subsequent cold rolling or hot rolling process.
