This matter of burning clay bricks to build a city wall is actually not difficult, and the reason why people in these years can't think of it is actually because they are not so boring.

You know, the clay pots and clay bowls fired at this time are not enough, who has nothing to burn a square clay brick to play!

Zhao Hao personally demonstrated, even if Cang Wudang understood, the matter of burning pottery bricks is much simpler than firing pottery, but it just needs manpower.

This person is easy to say, the Black Stone Department has, as long as Zhao Hao packs the food, even if he pulls two thousand people to burn the clay bricks, it will be no problem, anyway, the work of burning the clay bricks does not require much strength.

After the two of them had made a plan, Cang Wu began to prepare to dig a hole in the valley with the most clay, while Zhao Hao took Ah Yun and Ah Yue to continue to wander around the mountains and forests near the Black Stone Department.

He doesn't need to worry about this matter of firing clay bricks, Cangwu will naturally take people to do it, and he doesn't have to worry about the matter of delivering meat, at this time, his mother has a magic knife in his hand, killing cows and skinning or something, and his mother is also very easy to do, and he doesn't need his help.

What he wants to do now is to find iron ore and make iron!

Iron smelting was an idea he had for a long time, but he never found iron ore and didn't have time, so the matter fell down.

At this time, he finally had some time, so naturally he took Ah Yun and Ah Yue and hurried to find iron ore.

This iron ore, how to say, if it is on the plains, it is troublesome to find, but it is relatively easy to find in the wild jungle with dense mountains, because there is a high probability that there is that kind of exposed iron ore in the mountains and forests.

Zhao Hao wanted to find it himself at first, but he led Ah Yun and Ah Yue around the mountains and forests near the Black Stone Department for a day, but he still found nothing.

There was no way, in order not to delay the time, he could only ask Cangwu.

Of course, the question he asked Cangwu was not where there was iron ore, but where there were reddish-brown stones.

This question is naturally difficult to overcome, you know, he has been wandering around the mountains and forests around the Black Stone Department with the young men of the clan for twenty or thirty years.

Soon, he took Zhao Hao to a barren mountain less than an hour's walk from the Black Stone Department, where almost all the mountains were covered with reddish-brown stones.

Zhao Hao ran over and picked up a piece at random and looked at it, and suddenly he was excited, that's right, the stones here are iron ore, mountains of iron ore!

Of course, this iron ore cannot be used as iron, and it is not easy to refine the pig iron in it.

Zhao Hao had never done this work in his previous life, but he had seen it on TV that iron smelting is probably to put iron ore and coal together and burn it hard, and when the burned iron ore melts, the pig iron inside will turn into molten iron and flow out.

Such a seemingly simple process, but there are a lot of things to prepare.

First of all, there must be a furnace, an ordinary furnace is not enough, it has to be a furnace made of clay, and this furnace must be quite strong, otherwise, hundreds of catties or even thousands of catties of coal are poured into it, and the furnace will be fractured directly.

This stove, at the current level of the Black Stone Department, is logically impossible to make, but Zhao Hao has come up with a good method.

This method is also very simple, is to dig a large pit on the hillside, then fill the pit around the pit with a thick layer of clay, and then dig a hole under the pit, and finally make a thick clay pot like a water tank and put the hole to connect the molten iron.

It's not difficult to prepare these things, digging pits, that's Zhao Hao's specialty, clay, there are near the Black Stone Department, if you want a clay pot, the old style of the Black Stone Department will also do it, but it's not very beautiful.

These things were almost prepared in a day, and then Zhao Hao stuffed a large pile of coal and burned it in the furnace overnight, and the furnace was almost pottery.

Early the next morning, Zhao Hao began to experiment with refining pig iron.

He didn't know what the ratio of coal to iron ore was, in short, just put more coal and less iron ore, anyway, he was experimenting at this time, not mass production.

He directly stuffed five or six hundred catties of coal into the furnace, and a large pile of firewood underneath, but only about 100 catties of iron ore were stuffed in.

When everything is ready, just light a fire directly in the hole under the stove, because there is a hole in the hole under the stove that leads to the furnace, after all, this molten iron must also flow out of the furnace.

Shortly after the fire in the cave was lit, the firewood in the stove was lit, and a long waiting process followed.

This time, Zhao Hao burned for most of the day.

It's a pity that until all the coal in the furnace is burned, not even a little molten iron drips from under the furnace!

What's going on?

It seems that the temperature is not enough!

So, how do you raise the temperature inside the furnace?

Zhao Hao thought about it for a long time, and finally remembered that in some costume dramas, when building weapons, there was a big bellows next to the stove, and he kept pouring wind into the stove.

This bellows can't be done at the current level of the Black Stone Department, but Zhao Hao thought of a good way.

This method is also very simple, that is, cut a large tree thicker than a waist, take a piece of the trunk, hollow out the inside with a divine sword, and then stuff a wooden plug about the size of the hole in the inside to make something similar to a needle syringe.

After the syringe made of the trunk was ready, he made a hole next to the stove and stuffed it directly into it, and then he made a small hole in the corresponding position next to the furnace, and this bellows-like thing was ready.

On the third day, he prepared a large pile of firewood and five or six hundred catties of coal, and this time, he prepared dozens of catties of iron ore.

When everything was ready, he started to light the coal again.

However, this time, he didn't stand by and wait, he kept holding on to the big stick that had been drawn out of the trunk, pushing the piston quickly, and constantly pouring air into it.

This guy, as soon as the wind poured in, the fire was really much stronger, and the flames were several meters high.

This time, the coal in the furnace burned significantly faster, and in less than two hours, the coal inside was almost burning.

Finally, when all the coal in the furnace had been burned and the fire was about to be extinguished, he threw down the stick and carefully dragged the thick clay pot under the stove out of the hole.

It worked!

Although there is not much molten iron in the thick clay pot, it is probably as much as a scoop of water, but he did refine the molten iron.

Although this molten iron doesn't look very pure, and there are even some slags of unknown composition in it, it is indeed molten iron!

Looking at the gradually cooling molten iron in the thick clay pot, Zhao Hao couldn't help but sigh, Nima, it's really not easy to make some inventions and creations, it's even more difficult than hunting strange beasts close to divine beasts!