The blast furnace for iron-making was built on the banks of the Taizi River, and it was a blast furnace with a wide belly and a gradually narrowing neck, which looked a bit like a vase.

That's right, this blast furnace was rebuilt on the basis of the blast furnace of the Song Dynasty by Qi Ta and some experienced old blacksmiths according to Chen Dexing's idea.

Of course, there was a blast furnace in the Song Dynasty! According to records, during the Yuanfeng period of the Northern Song Dynasty, the military weapons supervisor of the imperial court set up blast furnaces on both sides of the Bianhe River, and the red light of iron-making reflected the sun and moon day and night. At the peak of production, the steel output in North China alone was as high as 150,000 tons! Although the steel output of the Southern Song Dynasty was not as good as that of the Northern Song Dynasty, there was also a concentrated steel smelting industry near Quanzhou, with an output of about 70,000 tons.

Moreover, the steel smelting technology of the Southern Song Dynasty has been improved compared with the Northern Song Dynasty, and some large blast furnaces can smelt tens of thousands of catties of pig iron at one time. Several blacksmiths under Zita who had been plundered from Lin'an and Mingzhou also presided over the construction of blast furnaces of different sizes.

But...... The iron smelting of the Song Dynasty, like the H medicine of the Song Dynasty and the fire gun of the Song Dynasty, always had several technical shortcomings, which limited them from playing their due benefits. For example, the formula of H medicine is always not quite right, and the fire gun is either too small or the raw materials are not right.

As for the iron of the Song Dynasty, the problem came from the sulfur and phosphorus!

Speaking of which, the Chinese are more unlucky! Most of China's iron ore is high in sulfur and phosphorus, and the ancients did not know how to remove sulfur and phosphorus, so they were used to make iron, and the smelted iron was naturally pig iron containing sulfur and phosphorus. The "wrought iron" fried by the iron frying method is, of course, unable to remove sulfur and phosphorus. In this way, no matter whether you use forged steel or crucible steel, there is no way to obtain satisfactory steel.

Therefore, the development of China's frying steel method and crucible steel is relatively slow, although both technologies are available. But it never matured. Otherwise, the infantry of the Song army should wear strong and light plate armor and carry mass-produced steel knives to the battlefield!

This steel plate armor. But the Mongol bows and arrows could not penetrate the defenses!

And now, the Chinese "science and technology tree" that is always in poor breath. Two of them have already been made up by Chen Dexing with a golden finger. And the third "technology tree" - steel, has also found a solution.

Speaking of which, we should still be grateful to the metallurgical industry of the Great Song Dynasty, if the Song people found large iron ore mines with low sulfur and low phosphorus (relatively few in the land of South China), they discovered the secret of coke. It is estimated that there is nothing to do with Chen Dexing, the king of salvation.

The blacksmiths of the Song Dynasty would not have used clay to build blast furnaces, nor would they have used pull-push blowers to make large wooden boxes. Chen Dexing, a seaman, even if he knew a little metallurgical knowledge of later generations, would be of no avail.

Now the blast furnace has been built, built on a huge rammed earth platform about five feet high. The blast furnace itself was two feet and a half feet high, and its internal volume was estimated to be five or six cubic meters - certainly not measured. And Zeta they don't know what a cubic meter is? They only know that this furnace can produce 8,000 catties of iron, which is about 4 tons. It is a little smaller than the large blast furnace in Quanzhou that can produce 10,000 catties of molten iron in this era.

However, this blast furnace, which was not the largest in the Song Dynasty, had a special place - high temperature resistance! In the lining of the blast furnace, refractory bricks fired from high-alumina clay were used.

Refractory material This was a key factor in the invention of the Pudlin churning method and the Huntsmann crucible steel in history, and it was necessary to create a refractory material that could withstand 1400 degrees Celsius and 1600 degrees Celsius before it was possible to develop a truly efficient iron frying method and crucible steel.

And this refractory material, that is, high-alumina clay, sounds very high and unfathomable. But in China, there is actually a very common similar clay - Guanyin soil! It is the white soil that was dug up to fill the hunger during the famine! This clay is not uncommon in China and is commonly used to make porcelain and pottery. This kaolin is ground into a fine powder, and then mixed with quartz stone powder and cristobalite powder (no addition). It is directly pressed into bricks, and can be fired into refractory bricks at a high temperature of more than 1300 degrees. This refractory brick can theoretically withstand temperatures of up to 1800 degrees.

Of course, the refractory bricks used by Zita and others to build blast furnaces are not of such good quality, but they are more than ordinary blast furnaces made of red bricks or clay. It is still able to withstand higher temperatures.

The problem of the blower has long been solved by the ancients. A flap push-pull bellows are used, powered by a water wheel. Two air chambers were arranged throughout the blast furnace. Two air ducts and two spare bellows. It can be replaced at any time.

In addition to the large furnace body, scaffolding was built out of sturdy wood. The top feeding system for adding chutes, pulleys and pulleys - pulley sets appeared on docks and boats in this era, and Chen Dexing only slightly improved them.

The molten iron smelted by the blast furnace is pig iron with high carbon content and many impurities, which can be used to cast large iron parts, so a groove is connected to the tap hole, which is usually closed, and can be opened to introduce the molten iron into the mold when needed.

Two iron-frying furnaces, the so-called reverberatory furnaces, were built next to the platform where the blast furnace was located, separating the fuel chamber from the furnace chamber, and the long flame formed after the fuel combustion was fed into the furnace, and the pig iron was heated by the reflection of the furnace top and furnace wall. Because the fuel chamber and the furnace chamber are separated, there is no need to heat the molten iron with coke, which can avoid the contact between impurities such as sulfur, phosphorus and carbon and the molten iron - because the product of the iron frying furnace is wrought iron that is basically free of impurities, so it is necessary to avoid contamination during the smelting process.

The so-called iron frying is to stir the molten iron with a long iron rod. Because the furnace temperature of this reflex iron frying furnace can only reach 1400 degrees, and after the carbon in the pig iron is removed to a certain degree, the melting point will exceed the furnace temperature, and the metal will become semi-solidified. It is necessary to rely on manual mixing to make the smelting continue.

Of course, this "iron frying method" was not "invented" by Chen Dexing, but appeared as early as the Han Dynasty and was also widely used in the Song Dynasty, but there was no concept of reverberatory furnace. In addition, steel can theoretically be obtained by this iron frying method, and the main product of the iron frying method is wrought iron, but sometimes a small amount of medium and low carbon steel is not completely decarburized.

Using this kind of fried steel, it is repeatedly folded and forged to obtain the so-called hundred steel, which is the high-grade steel used to make swords and swords.

The steelmaking method adopted by Chen Dexing and others is the crucible method. The crucible method has long appeared in China, the earliest can be traced back to the Spring and Autumn Period and the Warring States Period, and was most prosperous in the Han Dynasty, but it gradually declined in the Northern and Southern Dynasties - probably because the high-quality iron ore with low sulfur and low phosphorus was consumed, and the steel smelted with the crucible was of unguaranteed quality and high cost, so it was gradually eliminated. However, in some parts of Shanxi, there is a crucible iron-making process, and many experienced blacksmiths know how to make zuò crucibles. And Chen Dexing's help to them was nothing more than making crucibles and crucible furnaces out of refractory kaolin. This allows the crucible to be made at a higher temperature.

Later generations of Huntsmann crucible steel required a high temperature of 1,600 degrees Celsius for smelting, and crucibles made of ordinary clay simply could not withstand it. Of course, not enough furnace temperature does not mean that steel cannot be made, and the ancients were very able to understand the concept of improvisation.

On a small high slope a hundred paces to the right of the blast furnace and the iron furnace, two furnaces have been erected specifically for smelting crucible steel. Two columns of blue-black smoke were rising from there, apparently the crucible furnace was making steel. In a farther place, there is the wharf and the fence, the wharf is the place where the material is fed, and the fence is to prevent idle people from entering the fang area - the Nanfen Iron Workshop is located, which is naturally a military forbidden area! It is surrounded by the Nanfen city wall, two fences and moats, and the Taizi River. There are also troops stationed on patrols, and there is even a small "water army" on the Taizi River.

Chen Dexing also knows that the current process of "blast furnace iron-reverberatory furnace iron-crucible steelmaking" is also making do with steel-because the furnace temperature is difficult to control, the quality of refractory materials is unreliable, and the impurity content of iron ore is also difficult to determine. It is impossible to obtain high-quality steel from the later industrial era - but the steel smelted, both in quality and quantity, is enough to crush the steel handicraft industry of the Southern Song Dynasty, let alone the Great Mongolia. Therefore, we can't let this advanced iron-making and steel-making method leak out!

"Big brother, the blacksmiths and apprentices in our Nanfen Iron Workshop are all veterans. Here in Nanfen alone, five blast furnaces, fifteen frying furnaces and five crucible furnaces have been built. ”

Zita lightly introduced the R&D and exploration process of Nanfen Iron Workshop - even with Chen Dexing's suggestion, failure is inevitable! Coke ironmaking and reverberatory furnace frying are both new technologies, and although crucible steel is something that has been around for a long time, it is not very commonly used after all. Again, it needs to be explored repeatedly.

"Has any of the craftsmen in the ironworks made meritorious contributions?" When Chen Dexing asked, the blacksmiths and apprentices of the entire ironshop had already gathered and stood in three rows in front of Chen Dexing. There were about three or four hundred people, all of whom were craftsmen who were proficient in ironmaking and prospecting. Most of them were plundered from Lin'an and Mingzhou.

"Yes, Meng Datou, you come out." Zeta beckoned and summoned a small man of twenty hangers, no more than five feet tall, very thin, but with a big head, the frontal bone was wide and high, in stark contrast to the small body, like a thin bamboo pole supporting a big head, no wonder it was called "big head". This honor is not so much like a blacksmith as it is like a scholar.

"This is Meng Demeng's big head, don't look at him doesn't look like a blacksmith, but his head is easy to use." Zita pointed to the blast furnace and frying furnace behind him, "The blast furnace and the frying oven are all painted by him, the blast furnace is high, the layout of the frying furnace is also what he came up with, and the design of using pulleys to feed is also made by him." This kid is smart, but it's a pity that he hasn't read any books, otherwise he would have been able to get into the jinshi! (To be continued......)