Chapter 114: I Don’t Know If It Can Be Considered a Success
Yuan Ye set up camp with his men at the small river bay, prioritizing the extraction of black iron sand from the area. After all, it was outside his temporary territory. Even though it was still a wasteland, he figured no one would bother him for panning iron sand there, but it wasn’t his land, so he wanted to get the goods out first.
Just a few days later, this year’s plum rain season arrived, and the fine drizzle began to fall incessantly. Building houses and digging trenches was greatly affected, so he simply transferred most of the construction teams here. While panning the black iron sand that had accumulated naturally in the small river bay over the years, he also began constructing “iron fields” within his temporary territory.
Building iron fields was simple, with no technical difficulty. All that was needed was to shape a section of the river channel into a “terraced” form. When the river water carrying black iron sand flowed through this area, the continuous undulations in the water flow would slow it down, naturally causing the black iron sand to settle. Then, manpower would be used to remove the silt, and it could be panned nearby.
Of course, using large lodestones to directly attract iron sand would be faster. However, there was nowhere to find natural lodestones at the moment, so this would have to be improved upon later to increase efficiency.
For the entire plum rain season, his time was entirely spent on this black iron sand. He braved the wind and rain every day, his clothes never drying for more than half a day, wading through rain and mud. When the sun finally dispersed the clouds and he returned to work on schedule, he had worked on both sides and obtained over twenty thousand catties of black iron sand, which was a little over ten tons.
For now, this was enough. He transported this washed black iron sand back to Wanjin and spread it out to dry in the sun. After a moment of hesitation, he felt that it was difficult to completely control the smelting technology within himself, and he couldn’t guarantee that future technology wouldn’t leak. He decided to first smelt it using the ancient Japanese method, which was the “Tatara method” for smelting iron.
This was a matter of principle, and at least he had to try if it would work.
As for what the “Tatara method” was…
A tatara was a large wooden human-powered bellows, generally exceeding three meters in height. It used human pedaling as its power source to blow a large amount of oxygen-rich air into the furnace. Any smelting operation that used these large foot-operated bellows could be called the “Tatara method.”
Yuan Ye had made up his mind. He tried his best to recall the various details from the NHK documentary and reproduce them. His major in chemical machinery had some overlap with metallurgy, and at least he was very clear about the chemical reactions that would occur during smelting. Primitive mechanical devices were no challenge for him. Within two days, he had produced a set of blueprints.
With the blueprints ready, he then prepared the combustion agents, which were high-quality charcoal and limestone.
For the former, he already had a charcoal kiln, which was also prepared for the future gunpowder workshop and could produce high-quality charcoal. There was no shortage of good wood in this era. He sent people to search the mountains, specifically choosing mature trees with extremely dense wood, such as oak and Quercus trees, which in later generations would only be used for crafts. He burned several kilns of excellent charcoal, and then selected the best, which had even higher standards than the charcoal required for gunpowder.
It was truly good charcoal. The charcoal blocks had almost no visible cracks. They would only break when struck with force, and when they broke, they would shatter into pieces, with few fragments. Furthermore, the cross-sections showed a shining metallic luster, indicating absolutely excellent charcoal.
As for limestone, that was even less of a problem. Limestone was everywhere; they just had to dig it up and sort through it.
At the same time, he selected high-quality wood and, with the help of carpenters, built two “tatara” bellows, one on the left and one on the right. Then, in the open space in the middle, he laid the foundation, dug a pit three meters deep, compacted the bottom, laid a layer of fine sand and gravel, then a layer of charcoal to absorb moisture, followed by a thick layer of clay, and finally filled and leveled the pit carefully with large stones. If it wasn’t level, he filled it with lime powder.
This was to prevent ground moisture from seeping into the furnace and affecting the temperature inside.
Once the foundation was laid, he had people pile a large amount of clay on top and pound it down forcefully, shaping it into a square, tightly packed block of clay. Finally, he hollowed out the center into a funnel shape, and carved out passages for air intake and slag removal.
At this point, the furnace was considered built. He then directed people to dry-fire the furnace to thoroughly dry and set it.
Thus, with the ore, furnace, bellows, combustion agent, and fuel all ready, the smelting of iron sand could begin.
Yuan Ye was still very cautious. He repeatedly checked and thought through the process several times, and when he felt there were no omissions, he ordered his men to start filling the furnace.
A layer of charcoal, a layer of iron sand, a thin layer of lime, then another layer of charcoal, another layer of iron sand, and another thin layer of lime, until the furnace was filled to two-thirds capacity. Then, the furnace was ignited, and the bellows began to work. Two people on each bellows chanted in unison, pulling the bellows up and down like a seesaw, slowly blowing air into it.
The furnace did not hesitate. With a belly full of high-quality charcoal and no shortage of oxygen, the bright red flames immediately blazed up towards the sky, but soon slowly receded, the color began to shift to dark red, and at the same time, an astonishing amount of heat was emitted.
It was astonishing heat, at least for humans. Even though Yuan Ye was standing quite far away, he couldn’t stand his ground and retreated several more steps.
Iron smelting was a rare occurrence in this era and could even involve “family secret techniques.” A Man and the others naturally came to watch the excitement. Seeing that the fire had finally been lit, A Man immediately asked with concern, “How long will it take to see the iron material?”
This wasn’t just smelting iron; it was smelting money, so of course she had to care about it and hoped for an early success.
“About three days!” Yuan Ye replied softly, his gaze never leaving the furnace, afraid that this contraption would give him no face and crack open on the spot. Fortunately, the half-meter thick furnace wall was very sturdy and could withstand this small fire, which put him slightly at ease.
A Man nodded as if she understood but immediately asked, “Just keep burning it like this? Do we need to throw someone in?”
Yuan Ye’s main focus was still on observing the furnace’s performance. He didn’t react immediately to her words and asked strangely, “Why would we throw someone in?”
“With such a big commotion and such an important matter, shouldn’t we throw someone in? Just like building bridges and castles, don’t they require a human pillar?” A Man said as if it were natural, and the people around her showed no unusual expressions. It was probably common knowledge in this era.
Yuan Ye was rendered speechless. What was a human pillar? He was smelting iron, and suddenly human pillars appeared. He didn’t understand!
He looked around and saw many people gathered to watch the excitement, including Endo Chiyo, the “chief steward,” who was watching the raging fire with three little assistants, looking astonished. Not to mention others. He quickly waved his hand, signaling them to stop idling around. After satisfying their curiosity, they should return to their posts and continue contributing to the Wanjin territory.
After sending away the idle personnel and no longer worrying about losing face, he asked A Man, “What is a human pillar?”
“It’s a human sacrifice!” A Man was no longer surprised by his lack of common sense. Admiring the “spectacle” of iron smelting, she casually explained, “When building bridges or castles, or other large-scale projects, there’s a possibility of angering gods, earth spirits, or vengeful spirits, so someone needs to be buried beforehand to communicate and appease their resentment. For example, a person was buried in the pier of the Yodogawa Bridge, and that person has now become a Buddha, called… Hitobashira Jizo Bosatsu.”
She paused and added, “It’s the same for castle construction. There’s always some unlucky soul who gets buried first. Most castles in Owari have human pillars buried beneath them; otherwise, how could they be so stable?”
Yuan Ye was rendered speechless again. Every time he thought he was starting to adapt to this era, the era would slap him with a big mouth, presenting him with bizarre anecdotes that caused him psychological discomfort.
Or perhaps he had transmigrated to the wrong place. Other places were already in the 16th century; such things shouldn’t be happening, at least not as a common phenomenon.
He held back for a while, having nothing to say, and could only shake his head: “You’re not allowed to say such things in the future. We won’t do such things.”
“Alright, it’s your decision!” A Man was indifferent. After all, it was Yuan Ye’s own business. She didn’t understand iron smelting; she was just offering him advice and telling him what others would do when facing major events.
“You should go back quickly too!” Yuan Ye was starting to find her presence annoying. The furnace would need to burn for about three days, and he couldn’t let her be idle during this time.
As for himself, he naturally had to stay here. Currently, he was the only technical talent that could be found in Wanjin. At the same time, he had to keep records and improve the process, so he could only work harder.
After more than an hour, the color of the flames began to change again, gradually shifting from dark red to orange, and then gradually brightening. The temperature was likely increasing further. Yuan Ye covered his head and face and leaned in to observe. Combined with his imagination, he judged that the iron had sunk to the bottom of the furnace due to its own weight, and the impurities with lower melting points had begun to separate and float to the surface. He then ordered the bellows to stop and took a large iron ladle to quickly scoop out slag from the slag removal port in the center of the furnace.
After scooping out the slag, he ordered people to add new black iron sand, charcoal, and a small amount of lime from above, and to supply fresh air for a new round of smelting.
This was repeated continuously, and the temperature inside the furnace grew higher and higher. The flames finally turned golden yellow, faintly invisible even in daylight. It was now the third day, and the furnace finally cracked on the surface, having completed its historical mission. This primitive clay furnace was single-use; you had to reshape one after each smelting.
Yuan Ye’s eyes were now bloodshot. He quickly ordered people to stop the bellows and waited for several hours for the furnace temperature to drop. Then, he had people, heavily wrapped, rush up to break the furnace and remove the unburned charcoal.
The process was easy. The furnace wall, originally nearly half a meter thick, was only about ten centimeters thick after three days of burning. After clearing away all these miscellaneous items, only a large piece of “sponge iron” full of holes remained on the spot.
The entire smelting process, in essence, was that the carbon monoxide generated by the burning charcoal stripped oxygen from tetraphosphorus tetroxide and iron(III) oxide, turning them into carbon dioxide and releasing them into the atmosphere. Without oxygen, tetraphosphorus tetroxide and the like naturally turned into iron. However, the temperature inside the furnace was not high enough, far from reaching 1500 degrees Celsius. This iron did not completely melt into liquid and remained in a semi-solid state. Most of the impurities were burned away, and it finally became sponge-like with many holes on the surface.
Or, it became a lump of very poor quality iron-steel mixture.
Yuan Ye carefully examined this large lump of “sponge iron” and ordered people to break it while it was still hot, push it into a water pool to cool down, and then classify it by color. Most of it was inferior pig iron, which required further manual hammering to remove impurities before it could be barely used. A small portion was pure iron, and then there was a tiny bit of low-temperature carbon steel, “tamahagane,” which was accidentally produced by the reaction of pure iron with carbon monoxide.
The result was hard to say. Yuan Ye looked at the messy pile of iron and steel on the ground and didn’t know if he could consider himself successful.
