Three weeks later.

Su Mansion.

It was still the same small courtyard where Xu Yun previously prepared the generator.

At this moment, the courtyard had been cleaned up, even the stone tables and flowers had been moved away.

In the entire courtyard.

Only in the center was left a bizarre device with a brick-arched top, somewhat resembling a coffin.

Beside the equipment stood Old Su, Wang Bing and his brother, Zong Ze, Wang Hou, Siegfried, and...

An old man with white hair and beard, yet energetic and sprightly.

Of course.

Xu Yun was also present.

He was fully focused on the arched device's interior, not moving his eyes.

Estimating that it was about time, he turned his head and said to Old Chief Steward Xie:

"Old Chief Steward, you can stop now."

Upon hearing this, Old Chief Steward Xie quickly responded yes.

He turned around and halted the donkey that was pulling the bellows, and very kindly placed a large handful of grass in front of it:

"Hurry up and fill your stomach, you'll need to work again later."

Brother Lv:

"...."

Xu Yun then looked at Siegfried, who had been waiting there, cupped his hands and said with a smile:

"Master Qi, thank you for your trouble."

"Young master is too polite, it's just my duty."

Siegfried returned a very reliable look, took several craftsmen to the equipment, and used an iron rod to pry open a preset lid.

As the lid was pried open, a stream of intensely hot molten iron began to slowly flow into a small dug pond.

Next, according to Xu Yun's prior instructions, Siegfried lightly and evenly scattered pig iron powder into the molten iron in the small pond.

Meanwhile, several others stirred quickly with willow sticks.

Seeing this situation.

Xu Yun finally felt a bit relieved.

In ancient Huaxia, bai-lian steel and forged steel were the two most common steel casting methods.

Take the artifacts from the Song Dynasty's Artifact Bureau as example, the sulfur content was about 0.11% or roughly one per thousand.

Mentioned earlier.

The difference of each ten-thousandth in sulfur and phosphorus in steel makes a world difference, a completely different concept.

Modern steel technology basically uses this difference as the grade demarcation line, dividing into ordinary steel, high-grade steel, premium steel, peak premium steel, consummate premium steel, semi-transcendent steel, and so on.....

In summary.

Compared to the ten-thousandths five of modern ordinary steel, Song Dynasty ordinary steel products were six whole orders of magnitude worse.

Even compared to the best steel products of the Artifact Bureau, the grade gap at most shortened to about 4.5.

Thus, Xu Yun, following the 'task is to make a scene' idea, simply decided to go big:

He combined the Bessemer Steelmaking Method with the Late Ming's Ingot Steel Technique, and using the local 1956 small volume furnace as a template, designed a two-cubic-meter reflective furnace.

The so-called reflective furnace.

Refers to a chamber type flame furnace.

Fuel burns in its combustion chamber, and the heat generated is reflected by the furnace top to heat billets in the heating chamber.

Heat transfer inside the furnace relies not only on flame reflection, but more importantly on radiation heat transfer from the furnace top, walls, and hot gases.

Thus there are certain requirements in design specifications.

The reflective inverted arch furnace bottom Xu Yun adopted this time was brick-built, about 900 millimeters thick, layered from bottom to top as follows:

Furnace bottom cast iron plate, 20 millimeter asbestos board, 300 millimeter clay brick, 100 millimeter ramming material layer, and finally a top layer of magnesium brick inverted arch.

What?

You ask how to get magnesium bricks?

By calcining magnesite at high temperature, then crushing it to a certain size to become sintered magnesia.

After pressing, fine quality magnesium bricks can be obtained.

Considering the test preparation of Horse Iron Hoof melt ratio and depth were small, Xu Yun used a 129° arch center angle. (Shouldn't be wrong, 300 millimeters of magnesium brick, can anyone verify?)

Thus.

The furnace internal temperature could easily reach over 1600 degrees, even close to 1800.

Besides the equipment.

Xu Yun also made some improvements regarding raw materials.

For example, coking coal isolated from air, using coke instead of coal as fuel.

And using the Ingot Steel Technique for decarburization and so on.

Of course.

The more crucial step was another one:

Adding the bellows for pulling.

This step had no resource consumption, and no manpower cost, just a bit exhausting for the donkey.

After a while, Siegfried signaled to Xu Yun:

"Mr. Wang, the molten iron has turned spongy."

Xu Yun walked quickly to the spout, and as he neared, a wave of heat welled up:

"Master Qi, have all the pig iron filings been added?"

"All added."

Xu Yun nodded slightly:

"Then cut up the sponge iron and place it on the second layer, inject oxygen."

Having practiced the related procedures before, Siegfried, without much effort, transferred the molten iron with pig iron filings into the second layer of the reflective furnace.

The second layer temperature of the reflective furnace was much lower than that of the first; this stage's main purpose wasn't calcination, but...

Injecting oxygen.

Or more precisely...

Injecting pure oxygen.

Exactly.

Pure oxygen.

This was also why Xu Yun had confidence in forging steel with lower impurity content:

As everyone knows.

Producing pure oxygen is easy for anyone, surely no one doesn't know how, right?

Ahem.....

Considering the extremely high temperature of the reflective furnace, Xu Yun did not use electrolysis of water:

Electrolysis of water not only consumes a lot of energy but also tends to mix hydrogen gas.

Once hydrogen and oxygen concentrations reach a certain limit, some Deidara behaviors easily occur inside the reflective furnace.

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