Siheyuan: I eat melons while doing scientific research

Chapter 1246: Obscure and Difficult Content (4k words, 5k more to come)

The short furnace life is the biggest problem that Beijing Steel Plant is currently facing with its converters.

This doesn't mean there aren't other major problems. As Director Fan himself mentioned, there are still a few. But compared to others, this problem is undoubtedly the most prominent right now: the equipment lifespan issue. This is the most difficult problem plaguing all industries right now.

With the flapping of Gao Zhendong's butterfly wings, some issues have been resolved, but the furnace life of the converter is precisely the area where the butterfly effect has little impact.

"Have you analyzed the reasons for the short furnace life?" Gao Zhendong asked.

Although we have a lot of information about this converter, we have very little information about this particular part. The reason is simple – this thing is newly built and we haven’t accumulated much experience yet.

At this stage, our scientific research relies heavily on experience, with relatively little theoretical foundation. Moreover, the practical implementation of such engineering projects does indeed require time to accumulate and identify problems to the greatest extent possible.

That's why Gao Zhendong asked this question.

"We believe the main problem is with the materials; the furnace lining materials are inadequate. We've compiled statistics, and to date, the consumption of refractory materials in the steelmaking process is extremely high, reaching over 8-10 kg per ton of steel."

Materials are the culprit behind most current lifespan problems.

Refractory material consumption is a relatively easy statistic to track and verify. It doesn't take long to discover. As the name suggests, it refers to how much refractory material is consumed in the converter lining for every ton of steel produced.

Having obtained this data, Jinggang Steel Plant can clearly see that the material is substandard.

This is a very straightforward figure, and the data from Beijing Steel Plant made Gao Zhendong frown. It was indeed a bit high, but he didn't think that was the whole reason.

"I think the materials are a major issue here, but not the only reason. We need to recognize that material consumption is just what we see, but not necessarily the whole story. If we simply reverse cause and effect, we might overlook other factors, ultimately preventing a comprehensive solution to the problem."

Gao Zhendong didn't reveal the exact reason, but instead gave his comrades a lesson first. By this time, he had the qualifications and confidence to do so.

After hearing his words, the other comrades couldn't help but start exchanging ideas.

"Yes, Chief Engineer Gao is right. What exactly is causing the furnace lining material to be consumed so quickly? It's not necessarily just due to insufficient refractory grade."

"Regardless of the reason, as long as we upgrade the refractory material, we can overcome any obstacle with sheer force."

"It's not that simple. Improving material properties is difficult and has its limits. If you can improve them smoothly, that's fine, but what if you can't improve them, or you can't improve them to that level?"

"That's right. You can really make a living with one trick, but the problem is that the trick might not be good enough."

"But who knows what's going on inside this furnace? It's so hot, and there's no way to observe it."

"You can analyze it theoretically, but you have to observe everything directly, which isn't that easy."

"You wish! Observation is not easy, but do you think theoretical analysis is easy?"

These words left the comrade speechless. Yes, given the current situation, theoretical analysis might be even more difficult.

“Sigh, I can’t do it, but Chief Engineer Gao said it’s not just for this reason. Maybe he has a different idea. He’s different from us.”

Okay, now another comrade is stuck. That makes sense. Just because our group can't think of it doesn't mean that Chief Engineer Gao can't analyze it.

After everyone had spoken at length and still had no clue, Factory Director Fan said, "Chief Engineer Gao, what you said makes sense, but we can't find a solution for the time being. Do you have any ideas right now?"

He knew Gao Zhendong's habits to some extent. This guy never spoke without thinking. Since he was able to give such a reminder, it meant that he had probably discovered something.

Gao Zhendong nodded: "Comrades, what do you think is the main reason for the consumption of furnace lining?"

"High-temperature erosion! Simply put, it's burned!" the comrades said. This problem is so simple, which is why many comrades decided to upgrade the fire resistance rating.

Gao Zhendong remained noncommittal: "The refractory materials you used are magnesia-carbon bricks and tar dolomite bricks, right?"

Magnesia-carbon bricks are not refractory bricks made of magnesium and carbon. Doing so would not only fail to provide refractory properties but would actually make them burn even more intensely! Instead, they are refractory bricks made of magnesium oxide and graphite or other types of carbon. Magnesium oxide is resistant to high temperatures, while carbon plays a very counterintuitive role—it has antioxidant properties at high temperatures, which can prevent the refractory bricks from being oxidized and corroded.

As for tar dolomite bricks, they are essentially magnesia-carbon bricks, except that the magnesium oxide comes from dolomite and the carbon comes from tar. The difference in source and original composition leads to slight differences in performance.

Don't underestimate the somewhat rustic name "firebrick." The "Dirty Three" (a derogatory term for a US Navy aircraft carrier) couldn't find firebricks, so they bought them from the civilian market. The reason they bought them from the civilian market was because they couldn't get military-grade ones. They couldn't afford the high price of civilian ones and ended up buying from unscrupulous merchants, resulting in the boilers going "Boom!" Anti-aircraft carrier firebricks and anti-aircraft carrier toilets are classic jokes about the "Dirty Three."

"Yes, yes, yes." The comrades from Beijing Steel Plant nodded repeatedly.

Gao Zhendong laughed: "Have you comrades considered this? Magnesium oxide has a melting point of over 2800 degrees Celsius, while the molten steel we use in steelmaking is only 1600 to 1700 degrees Celsius. How do we burn off the magnesium oxide?"

Ah... many comrades were immediately stunned. This... right, how did it burn? It's still far from the melting point of magnesium oxide.

"So, Chief Engineer Gao, you mean that the consumption of refractory materials is not that simple, and it's not just a physical process?"

“Yes, I believe that the consumption of refractory materials is the result of both physical and chemical processes,” Gao Zhendong reminded.

"Chemistry... Chief Engineer Gao, are you referring to iron oxide?" Iron oxide readily reacts with reducing agents at high temperatures.

"Yes, that's exactly what I mean. Chemical corrosion of the furnace lining is a problem that cannot be ignored, and it becomes even more serious under high-temperature conditions!" "But magnesium oxide and iron oxide don't react directly at high temperatures, right? Otherwise, we wouldn't dare to use materials with magnesium oxide as the main component for furnace linings at all."

Gao Zhendong shook his head and laughed, "That's not necessarily true. FeO and MgO can form an infinite solid solution. In this case, the furnace lining, which is mainly composed of magnesium oxide, will be corroded."

An infinite solid solution refers to two substances that dissolve in each other in any proportion in the solid state, with no limit to their solubility.

Huh? This works too? For a considerable number of people, the concept of an infinite solid solution is probably unheard of, but they can understand the word "solution." After hearing Gao Zhendong's explanation, they understood a little. And those few who knew about this probably hadn't even considered it.

"Ah, Chief Engineer Gao's reminder is so timely! FeO and MgO can indeed form an infinite solid solution, which should indeed be one of the reasons why refractory bricks are eroded and peeled off!" The FeO-MgO infinite solid solution system was discovered between the 30s and 40s, and it is a bit obscure. It took some effort for someone to remember it.

"Although I haven't conducted any experiments, I can infer that as the percentage of FeO in the converter increases, the rate of erosion of the furnace lining increases, and this increase may even be exponential!"

Listening to Gao Zhendong's bold deduction, the comrades were filled with admiration. What is theoretical deduction? This is theoretical deduction!
So much can be deduced from an infinite solid solution system that was only discovered two or three decades ago.

Gao Zhendong deduced that he dared to be so bold because he had knowledge in his head, so he wasn't afraid of misleading his comrades.

"Chief Engineer Gao, we'll go back and organize an experiment to see just how serious the situation really is!" Factory Director Fan said. He trusted Gao Zhendong's words completely, so what he wanted to verify was not "whether it is" but "how serious it is".

Gao Zhendong smiled and said, "Based on my personal research, I suggest that you control the total FeO content in the slag below 15%."

His words reminded the comrades of the actual situation at the converter—for a considerable period, the total FeO content in the slag was 20%. This figure was no coincidence with the one Chief Engineer Gao had just estimated.

"Speaking of this, we're having a headache too. The stirring ability during the smelting process is poor, the slag formation speed is slow, the melting process is prone to splashing, and the FeO content in the slag is not coming down." Director Fan was also having a headache. He originally thought it was a small problem, but he didn't expect it to be a big problem.

Gao Zhendong laughed even harder: "That's easy. I see you're using a single-hole oxygen spray gun. Just add a few more holes and change it to a three-hole spray gun!"

Well, when it's time to be simple and direct, Chief Engineer Gao is just as simple and direct.

While converting a single hole to a three-hole hole isn't just about adding two more holes, this solution is undeniably aesthetically pleasing despite its seemingly drastic nature. A single hole won't do, right? Then I'll go for a three-hole one!
Gao Zhendong's suggestion was actually implemented more than ten years later, and it worked very well. He just proposed the plan ahead of time.

Factory Director Fan readily agreed: "Yes, that's a good idea. We'll go back and figure out how to improve the equipment."

This wasn't blind obedience; rather, he had thought about it and realized it was indeed a very good approach, though the details needed to be tested and researched.

At this point, a comrade seemed to have been pondering for a long time before emerging from the "infinite solid solution" concept: "Chief Engineer Gao, since this infinite solid solution is a dissolution, it must still be physical erosion rather than chemical erosion, right?"

Gao Zhendong shook his head: "No, this phenomenon is related to both physics and chemistry, but it is not a simple physical or chemical reaction. Those of us who have studied it to this extent should know that the original distinction and definition between the two are actually no longer appropriate. This is a physicochemical phenomenon."

Chief Engineer Gao's position is still superior! It's just that the content he talked about today was a bit obscure, and some comrades found it a bit hard to handle.

At this point, Gao Zhendong added, "I haven't finished yet. Pure chemical erosion does exist; the reaction between FeO and impurities in the furnace lining is chemical erosion. But the biggest source of chemical erosion is the carbon in the magnesia-carbon bricks."

"Isn't the carbon in magnesia-carbon bricks used to inhibit oxidation reactions?" the comrades asked, somewhat puzzled.

Gao Zhendong nodded: "That's right, but too high a carbon content is not a good thing either. Carbon will be oxidized and decarburized in this process. If the carbon content is too high, the decarburization will cause the furnace lining material to become loose and eventually peel off."

Finally, we've entered the field of furnace lining materials. The comrades were excited. In any case, furnace lining materials are the most important foundation for improving this matter.

"So how exactly do we determine this?" Director Fan asked the most important question on behalf of his colleagues.

Gao Zhendong stood up: "Let me design a set of refractory materials for you."

He decided to give the answer directly because the absurd thing about materials science is that many times you can only rely on exhaustive trial and error. So, skipping the process and giving the answer directly will not cause the research process to be missing and the colleagues' foundation to be weak. After all, when you work on the next material, you still have to continue exhaustive trial and error.

As for the potential impact of accumulating basic data or increasing work experience, Gao Zhendong believes that none of these are as important as resolving the steel production issue as soon as possible.

His words left his comrades momentarily bewildered. Wasn't Chief Engineer Gao an expert in steel? This stuff had nothing to do with steel.

Speaking of this, the Northeast Carbon Research Institute, Institute 1761, and the Twelfth Ministry of Machinery Industry have something to say: who says he's only good at steel?

But no matter how surprised the comrades were, Gao Zhendong's direct answer still delighted them. Time, what we need now is time!
Gao Zhendong began writing down the process of this lining material on the blackboard. This was the technology used by the Beijing Iron and Steel Plant to set a new furnace life record in 1978. In terms of origin, it may not seem as advanced as the technology of the 21st century, but it is the technology most in line with this era. Because it was relatively recent, the effect was very obvious.

Even if Gao Zhendong were to acquire 21st-century technology and craftsmanship, he might not be able to utilize it effectively in this day and age.

"Ah, I understand now. The core of Chief Engineer Gao's process is to carefully select raw materials and control the quality of refractory bricks through secondary calcination, thus solving the problem at its source!"

"Okay, stop arguing, hurry up and write this down. This is a precise ratio down to two decimal places, plus clear process instructions throughout! If you miss a single word, you'll regret it!"

The furnace body is made of two-step calcined synthetic magnesia dolomite oil-impregnated bricks, which are combined with synthetic magnesia light-calcined oil-impregnated pitch bricks for the furnace mouth, tap hole and furnace cap, as well as dolomite pitch-bonded bricks for the molten pool, charging side and permanent layer.

"This set of bricks is much more complex than the ones we use. It's very well thought out and comprehensive. Different types of bricks with different properties are used for different parts. It looks reliable."

"Well, what's rare is that although it's complicated, the technical difficulty isn't high, and we can definitely produce it with our current conditions."

"I feel that this combination of furnace bricks and iron oxide suppression can really extend the furnace life by a lot."

(End of this chapter)