Daqin Engineers

While preparing these, Shen Bing organized an iron smelting workshop in the city.

The iron smelting workshop was placed in a barracks by Shen Bing.

This is very rare, because all countries, including the State of Qin, do not pay attention to iron smelting at this time... The technology has not kept up, and iron products can only be used for agricultural production, so of course it is not taken seriously.

But of course it was different in the hands of Shen Bing.

The reason for placing it in the barracks is of course confidential.

For this reason, Shen Bing had to bring the blacksmith's family and gather together to send soldiers to watch. This is what others call "hostages."

Shen Bing didn't want to do this, but one is to protect the safety of the blacksmith's family, and the other is to use it as a quality.

This is what Shen Bing said to the blacksmith:

"Iron smelting is not trivial."

"I am waiting to fight the Huns outside the Great Wall. Once the technique of smelting is leaked to the enemy, the Central Plains will be in trouble."

"So Shen Bing has to act carefully, I hope you forgive me!"

This also makes sense.

That is to say, it is the enemy, the Huns, and foreigners who are so strictly confidential.

What's more to say, of course, it must be defended to death, otherwise if this technology is leaked, the weapons and equipment made by the Huns will be used to attack the Central Plains and kill the people...

Although the various countries in the Central Plains fight back and forth, they have never been vague about resisting foreign aggression, especially the brutal Huns, and the people all agree.

How would they think that Shen Bing defended not only the Huns, but also Zhao Gao and Li Si.

Bian and Xiao didn't think there was anything at first, and they even thought Shen Bing was a little too cautious.

Because most of the Xiongnu inhabited by water and weeds, there was no demand for arable land or iron ore, so they would not have much interest in iron smelting technology...

In fact, the Xiongnu had always relied on the copper and tin of the Central Plains in the production of weapons.

In other words, they do not smelt themselves because they have no technical reserves for smelting and also lack the knowledge of mining.

They usually exchange horses and furs for copper and tin with countries in the Central Plains at the border, and then use them as raw materials to make necessary weapons and equipment.

Therefore, Jia Yi, a celebrity in the Han Dynasty, even suggested that Emperor Wen of Han control the outflow of copper and tin from the border of the Central Plains to weaken the Xiongnu's combat power.

The idea is good: Without copper and tin, the Huns could not make more weapons, so they could easily be defeated.

The problem is that it is basically impossible to achieve.

The reason is that the Xiongnu's demand for copper and tin is there. If the Central Plains controls its outflow, the price of copper and tin for the Xiongnu will soar... Originally, one catty of copper was exchanged for one horse, and then one catty of copper was exchanged for two horses even more.

The high-quality horses of the Huns are urgently needed by the Central Plains, and they can be sold at high prices immediately when they are shipped to the mainland.

Driven by this huge interest, the unscrupulous profiteers and even the common people in the Central Plains would smuggle copper and tin to the Xiongnu like crazy and desperately.

The end result is that the Xiongnu can still get the raw materials they need, but they lose more horses and fur.

As I said before, the iron tools of this period can only be used to make farm tools but not weapons. The Xiongnu did not cultivate land, so they had no interest in iron at all.

No interest in iron, of course no interest in iron smelting technology.

Knowing this, Bian Heqian thought that Shen Bing had made a fuss about keeping the Xiongnu's iron smelting technology secret.

However, they soon discovered that they were wrong...

Shen Bing handed Bian some drawings in the first place, and said:

"The blast furnace is shaped like this."

"The whole is oblate, and the air vents are located on both sides of the flat."

"And the furnace wall at the bottom of the blast furnace is inclined 62 degrees outward..."

Bian looked dumbfounded:

"General, what is sixty-two degrees?"

Shen Bing gave a "uh", and then took out another drawing to explain:

"I can cut the semicircle into one hundred and eighty equal parts, each of which is one degree."

"So the outward inclination of the blast furnace is exactly the same."

Ben heard that he understood, but he didn't know why he had to do it so hard, he just gave a vague "Oh", and then looked at the owe standing aside with a look of help.

He thought he owed a longer time with Shen Bing, so he would know more about these.

Unexpectedly, owing is also a confused look.

They certainly don't know why they did this. These are all iron smelting techniques of the Han Dynasty.

Needless to say why the blast furnace is made into an oval shape, it is to blow air into the core of the furnace, so that the temperature in the furnace can be higher and the carbon in the molten iron can be oxidized as much as possible.

As for the inclining furnace wall at the lower part of the blast furnace, it is for the coal to burn fully...

When the wind is limited, the combustion of oxygen and coal in the blast furnace will produce combustible gas.

If the lower part of the blast furnace is not inclined outward, the gas will be quickly discharged along the updraft of the furnace wall, which is not only a waste but also pollutes the air.

The inclination of the lower part of the blast furnace will change the internal air circulation mode and increase the contact area between the gas and the charge, so the gas will be burned in the furnace.

Of course, Shen Bing couldn't explain these things to Bian Heqi, especially these things were summed up by the ancients after hundreds of years in practice, and Shen Bing couldn't explain it clearly.

So he pretended not to see the confusion on Ben He Xiao's face and asked:

"But is it difficult to make this blast furnace?"

Ben and Xiao answered quickly:

"Back to the general, there is no difficulty."

"The subordinates will definitely make it according to the general's request."

This is indeed no difficulty. If you can make a round blast furnace, you can naturally make this blast furnace that Shen Bing requires. It just changes the shape.

In addition, Shen Bing also sent people to find limestone...

The problem of smelting iron from coal is that there are too many impurities in coal. If it is smelted in this way, although mass production can also reduce the carbon content of iron, the sulfur content has risen sharply, resulting in little improvement in iron quality.

Limestone is added to solve this problem.

In addition, a large amount of slag will be produced in the process of iron smelting. The slag contains a lot of silica, which will cause the slag to adhere to the blast furnace with high viscosity and difficult to remove.

After adding limestone, silica will react with calcium oxide to reduce the melting point of the slag, making it easier to remove.

Naturally, water drains are used for blowing equipment.

It's just that there is no river in the barracks.

For this reason, Shen Bing also specially let people open a small canal from the Yellow River... This not only solves the hydraulic problem of water drainage, but also solves the water problem of iron smelting.

Out of caution, Shen Bing also sent soldiers to block the canal with fishing nets and guard it day and night...If there is a river, it is easy to leak secrets, such as using a bamboo tube with letters or something and throwing it into the river without knowing it. The information was passed on.

After doing this, all that is left is to start smelting.