While preparing these, Shen Bing organized an iron smelting workshop in the city.
The iron smelting workshop was placed in the military camp by Shen Bing.
This is very rare, because at this time, all countries, including the Qin State, did not pay attention to iron smelting...the technology had not kept up, and iron products could only be used in agriculture, so of course they were not taken seriously.
But of course it will be different in Shen Bing's hands.
The reason why it is placed in a military camp is of course confidentiality.
For this reason, Shen Bing had to bring the blacksmith's family and gather them together and send soldiers to guard them. These are what others call "hostages".
Shen Bing didn't want to do this, but partly to protect the safety of the blacksmith's family, and partly to use it as a pledge.
Shen Bing said this to the blacksmith:
"Iron smelting is no small matter."
"We are fighting against the Huns outside the Great Wall. Once the smelting technique is leaked to the enemy, there will be a great disaster in the Central Plains."
"So Shen Bing has to act with caution. I hope you will forgive me!"
This also makes sense.
That is to say, what is kept strictly confidential is the enemy, the Huns, and foreigners.
What else is there to say? Of course, we must guard against it with all our might, otherwise if this technology is leaked, the weapons and equipment made by the Xiongnu will be used to attack the Central Plains and kill the people...
Although the countries in the Central Plains were fighting internally, they had never been vague about resisting foreign invasion, especially the brutal Xiongnu, and the people unanimously agreed.
How could they have imagined that Shen Bing was not only guarding against the Huns, but also against Zhao Gao and Li Si.
Ben and Qian didn't think it was anything at first. They even thought Shen Bing was a little too cautious.
Because most of the Xiongnu lived in pursuit of water and grass, and had neither the need for cultivated land nor iron ore, they would not have much interest in iron smelting technology...
In fact, the Huns have always relied on copper and tin from the Central Plains for weapon production.
In other words, they do not smelt themselves because they do not have the technical reserves for smelting and lack the knowledge to mine.
They usually used horses, furs, etc. to exchange copper and tin with the Central Plains countries at the border, and then used them as raw materials to make the necessary weapons and equipment.
Therefore, Jia Yi, a famous scholar in the Han Dynasty, even suggested that Emperor Wen of the Han Dynasty control the flow of copper and tin on the border of the Central Plains to weaken the Xiongnu's combat power.
The idea was a good one: without copper and tin, the Huns couldn't make more weapons and could easily defeat them.
The problem is that it's basically impossible to implement.
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 in the Xiongnu will skyrocket... Originally one pound of copper was exchanged for one horse, but one pound of copper was exchanged for two horses. even more.
And these high-quality Xiongnu horses were in urgent need in the Central Plains, and they could be sold at high prices immediately after being shipped to the mainland.
Driven by this huge profit, unscrupulous businessmen and even ordinary people in the Central Plains would go crazy and desperately smuggle copper and tin to the Xiongnu.
The end result was that the Xiongnu could still obtain the raw materials they needed, but only lost more horses and furs.
As mentioned before, the iron tools of this period could only be used to make agricultural tools and not weapons. The Huns did not cultivate the land, so they had no interest in iron at all.
I have no interest in iron, and I certainly have no interest in iron smelting technology.
Knowing this, Bian Heqian thought that Shen Bing was making a fuss by keeping the iron-smelting technology secret from the Xiongnu.
However, they soon discovered that they were wrong...
Shen Bing immediately handed Ben a few drawings and said:
"Made the blast furnace into this shape."
"The whole is oblate, and the air blowers are located on both sides of the flat."
"And the furnace wall at the bottom of the blast furnace tilts outward at 62 degrees..."
Ben looked confused as he listened:
"General, what is sixty-two degrees?"
Shen Bing said "uh" and then took out another drawing to explain:
"We can cut the semicircle into one hundred and eighty equal parts, and each part will be one degree."
"In this way, the outward inclination angles of the blast furnace will be exactly the same."
Ben Ting understood it, but had no idea why he bothered to do so. He just said a confused "Oh" and then looked at Qiu who was standing aside with a look of help.
He thought that if he stayed with Shen Bing for a longer time, he would have a better understanding of these things.
Unexpectedly, Qian also looked confused.
Of course they don't know why they do this. These are iron smelting technologies from the Han Dynasty.
Needless to say, why the blast furnace is made into an oval is to blow air into the furnace core, which can not only make the temperature in the furnace higher, but also allow as much carbon in the molten iron to be oxidized as possible.
As for tilting the furnace wall at the bottom of the blast furnace outward, it is to ensure that the coal is fully burned...
When wind power 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 tilted outward, the gas will be quickly discharged along the rising airflow of the furnace wall, which is not only a waste but also pollutes the air.
The tilt of the lower part of the blast furnace will change the internal air circulation pattern 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 Ben Heqian, especially because these were summed up by the ancients over hundreds of years in practice. Shen Bing couldn't explain them even if he wanted to.
So he pretended not to see the confusion on Benhe Qi’s face and asked:
"But is it difficult to make a blast furnace of this shape?"
Benhe Qian quickly replied:
"Return to the general, there is no difficulty."
"I will definitely make it according to the general's requirements."
This is indeed not difficult. If you can make a round blast furnace, you can naturally make the blast furnace Shen Bing requested. It just changes the shape.
In addition, Shen Bing also asked people to find limestone...
The problem with smelting iron from coal is that there are too many impurities in coal. If it is smelted in this way, although it can be mass-produced and the carbon content of iron can be reduced, the sulfur content will rise linearly, resulting in little improvement in the quality of the iron.
Limestone was added to solve this problem.
In addition, a large amount of slag will be produced during the iron smelting process. These slags contain a large amount of silica, which will cause the slag to be highly sticky and adhere to the blast furnace and difficult to remove.
After adding limestone, the silica will react with calcium oxide to lower the melting point of the slag, making it easier to remove.
Naturally, the blowing equipment used is water drainage.
But there is no river in the barracks.
For this reason, Shen Bing specially asked people to open a small canal from the Yellow River... This not only solved the hydraulic problem of water drainage, but also solved the water problem of iron smelting.
Out of caution, Shen Bing also sent soldiers to block the upstream and downstream of the canal with fishing nets and guard it day and night... When there is a river, it is easy to leak secrets. For example, if you put a letter or something in a bamboo tube and throw it into the river, you will not be aware of it. The information was passed on.
After doing this, all that's left is to start smelting.