After the excavation of Leshanyan was on track, Li Su was too lazy to continue inspecting Nan'an County. Anyway, the subsequent physical work was copied as planned and he could do about half a year.

The living conditions in Nan'an are not good, so I just leave them to the grassroots supervisors and military supervision.

However, I came to Jian for the sake of coming. Before returning to Chengdu, Li Su was not hesitant to go around the hundreds of miles to the road, and take a walk in Zigong to supervise the cause of steelmaking.

Li Su arrived in Wudao County on February 23rd. He only had a few people with him. In addition, Zhuge Liang, who studied with him, "reading thousands of books and traveling thousands of miles". None of the other famous officials came. Zhuge Jin and Xun You were both doing other things in Chengdu and Nan'an.

The reason why he brought Zhuge Liang was to hope that he would gain more knowledge and know what the sufferings of the people in all walks of life were like. After all, Zhuge Liang, who was in the later generations, had eleven years of farming around Longzhong and studying around him.

Li Su always felt that that experience was of great help to the formation of Zhuge Liang's personality and rich experience. In this life, Zhuge Liang had no time to farm and work in person for a long time, so he had to take him to inspect all walks of life to quickly make up for this shortcoming. And maybe he could see the operation of the iron smelting industry, and Li Su could teach him some good knowledge of chemistry.

Because it was just a temporary inspection, the construction of the local iron smelting workshop had lasted for more than two months before Li Su arrived at Wu Road.

It can be said that during the slack farm in the last winter, after the iron ore and anthracite arrived, the local government had already done some basic work to expand the iron smelting workshop under the leadership of Chen Shi, the prefect of Jianwei. After Li Su arrived, he would just take a quick look at the semi-finished product state and give a quick guide to improve it.

Zhuge Liang, who was just fourteen years old after the New Year, was the first time in his life to enter the back hall of the iron smelting workshop. He was quite curious and cherished the opportunity to study. After all, he was young. He had only seen blacksmiths forging iron that had been initially removed from impurities, or forging steel by hundreds of refining methods, but he had never seen the process of iron turning from iron ore to thick iron.

Zhuge Liang could feel that Master Li had high expectations for him, as if he was much taller than his brother who had become a county magistrate, and he was not strict. But it was this expectation of "big brother watching you" that made Zhuge Liang feel a little stressed, and he would not dare to slack off than directly putting on the ruler and stern reprimanding.

Similar to those motivated academic masters who occasionally miss the exam and go home, they would rather be beaten or insulted than be watched by cold violence with compassion and sympathy for the past month.

Compared to Zhuge Liang's curiosity and fear of slacking off, Li Su's mood was much easier, and he occasionally had some small surprises and surprises during inspections.

To be honest, Li Suyuan had never cared about the production process of "iron ore to rough iron" before, and had never visited the site, but only paid attention to the forging and processing. Therefore, under the leadership of Chen Shi, Li Su was also amazed when he visited the largest "blast furnace" newly built in Nadao.

Chen Shigang led Li Su into the workshop and proudly showed off: "General Right, this furnace is two feet wide and more than half a meter deep. The furnace temperature is very hot. Even if you don't use smokeless peat and only use charcoal, you may still have thousands of kilograms of iron on the sun, which is no less than the country's important weapon in the Jingluo area back then."

Li Su nodded frequently and asked some literacy questions. Only then did he realize that in the late Western Han Dynasty, the early Eastern Han Dynasty, there was already an original "soil blast furnace" in iron smelting, which was not rare. In theory, buildings that used clay pits to achieve smelting and closed furnaces were all considered natural blast furnaces, so as long as you can build a sealed porcelain kiln with a temperature of more than 1,100 or 200 degrees in the kiln, you can create a earthen blast furnace.

In the early years of the Eastern Han Dynasty, the largest blast furnace in the imperial court was located in the Xingyang area east of Luoyang. It was run by the state and the iron produced was also used by the supporting craftsmen in the capital's arsenal.

The furnace size is one to two meters long and wide, but the height is very short, less than half a meter. The inner furnace is clay walled and there is no refractory brick technology, so the furnace temperature is at most 1,200 degrees. The largest furnace in Xingyang is said to train more than 100,000 kilograms of iron for the court every year, which is about 300 tons in the later generations, accounting for nearly 30% of the national iron production in the Eastern Han Dynasty.

It can be seen that the iron furnace in Xingyang was definitely a national weapon in the Eastern Han Dynasty, and it was also an important guarantee for the Emperor of the Eastern Han Dynasty to ensure that the metallurgical and martial arts near the capital could crush the local foreign vassals.

At this moment, the initial principles and ideas of the iron furnace that Chen Shizai made here are obviously the same, but the scale and technology are different.

However, after a brief initial visit, Li Su was still a little confused.

Although Li Su was a liberal arts student in his previous life, he still knew that the knowledge point of the middle school chemistry test was quite solid. The melting point of pure iron was about 1,500 degrees.

According to the introduction of the craftsmen, Li Su knew that this kind of furnace in the late Han Dynasty could only reach 1,200 degrees at most, and it could melt iron. Of course, the craftsmen could not say the concept of "1,200 degrees". So their description at that time was that "the furnace temperature could be increased by more than 100% after the pure copper was completely melted." Li Su knew that pure copper was about 1,000 degrees, and the furnace temperature was about 1,200 degrees.

Li Su couldn't help but catch a craftsman leader on the scene to consult: "This father-in-law, before asking for the name Gao, the temperature of the furnace seems to be insufficient to melt pure iron. How did you make the iron?"

The craftsman leader looked at the prefect Chen Shi at a loss, and then knelt down quickly: "The right general is old and dare not call him noble. The old surname is Zhou Bing. The right general really understands this question. This pig iron thing should not be melted at the furnace temperature like this.

However, based on the thirty years of experience in old iron smelting, the more impurities this pig iron has, the lower the temperature required to melt it into molten iron. In the past, when high-quality charcoal was used to smelted, the furnace temperature was burned to the extreme, and it was only red heat softened and did not flow. However, if smokeless peat or charcoal with some sulfur, the iron produced was poorer and the impurities became brittle, but the iron was indeed easier to produce.

When I was young, it was around the end of Emperor Huan's dynasty, and I worked in Xingyang Furnace in Luoyang for several years. My master also taught me this way. Later, I explored for several years before I mastered the measure myself."

When Li Su heard this, he nodded slightly. Unexpectedly, this old blacksmith named Zhou was still a "senior talent" who had been through the top national factory around Luoyang.

Li Su couldn't help but change the topic and first asked him how he got into Shu. Later, he found out that it was when Liu Yan entered Shu that he had invested a lot of money to dig up some military technical talents from Luoyang.

Li Su couldn't help but complain: "It seems that Liu Yan was disobedient when he first entered Shu. He even poached the military technical backbone of the imperial center, and he was quite keen and attached so much importance to related industries."

Then, Li Su asked Zhou Bing about the difficulty of making iron and iron from various fuels mixed with impurities. After thinking about it for a long time, he finally understood this matter using the chemical principles of his previous life:

There is a basic knowledge point in junior high school chemistry textbooks, that is, "The melting point of pure metals is the highest, the melting point of alloys is lower, and the more components the impurities mixed into the alloy, the lower the melting point."

There was no 1,500 degrees of melting furnace in the late Han Dynasty. If you could not refine pure iron, you would expect doping to reduce the difficulty of melting at the expense of the quality and purity of the iron.

Therefore, after using charcoal to make iron smelting a few percent of carbon, phosphorus and silicon remaining in the iron, the melting point can be reduced to more than 1,200, and it will almost be burned into a relatively thin paste. If anthracite is used, anthracite will also be mixed with a small amount of sulfur, which may further reduce to 1,150 degrees.

Therefore, the quality of iron refined with anthracite is actually worse than that of charcoal, because with more sulfur impurities in the coal, the iron is more brittle and weaker. But the advantage is that the output can be increased to 2.5 times at once!

After all, the thinner the molten iron, the faster the reduction reaction efficiency, the faster the reaction speed of the molten iron and the mixed reducing agent, and the faster the oxygen in the ore iron oxide is taken away. A good-quality molten iron takes two and a half days to react, and a thin molten iron like pure water can be reacted in one day.

This is to increase the production speed to 2.5 times in exchange for the production of worse iron! This is why until the Tang and Song dynasties, the "Fujian iron" with scarce output was high-quality iron. From the sword-making masters in the late Spring and Autumn Period to the Longquan swords in Fujian, they were all ripped with sulfur-free charcoal. There was no coal there and it was absolutely not stained with sulfur elements in the coal.

"After a long time, the people of the Song Dynasty made the iron production soar to almost three times because of the introduction of coal. It was at the expense of a certain amount of iron quality... This is not a good thing. We must take into account both quality and output. The iron used to build weapons must also be desulfurized, or other processes are added to the last step of the reaction..."

Li Su was very alert to this question and felt that he could not let it go.

After thinking about it, Li Su found that the best solution was to continue to increase the furnace temperature.

After all, the reason why the iron smelting solidifies in the end is that after a coal and other reducing agent is put into use, the oxygen element in the iron oxide is reduced. The purity of the iron becomes higher and higher, and the melting point becomes higher and higher. In the end, it exceeds 1,200 degrees. So it solidifies in a furnace of 1,200 degrees, and it cannot continue to react quickly with a high exchange ratio of liquid state.

After Li Su and Zhou Bing got to know that the current "hundred refining methods" and even the "steel stir-frying method" that has taken shape, the purpose is actually one, that is, "after the crude iron is no longer in the state of molten iron, try to make the contact area and reaction area between the iron and the reducing agent as large as possible, so that the reduction reaction will continue and further react the impurities inside."

Of course, Zhou Bing’s original words did not say that. This was translated by Li Su based on the experience of craftsmen and his own knowledge of chemistry.

History books say that when the Tang Dynasty came to the "steel filling method", the reaction efficiency of steelmaking is much better than that of steel stir-frying method. The reason is that the reaction area of ​​liquid molten iron is large and the permeability is high.

The high furnace temperature can make the liquid high-efficiency reaction time last longer! The repellent of the iron for one hour is equivalent to the reaction of "liquid reducing agent poured on solid coarse iron" for three or four hours, which is equivalent to "scattering the solid fine particle reducing agent on solid coarse iron" for a long time, and it is also equivalent to "large solid reducing agent hitting on solid coarse iron forged" for several days.

After thinking about it, Li Su thought of the simplest move: if you can't increase the flame temperature of the fuel, you can reduce the heat loss during combustion.
Chapter completed!