The inside of the blast furnace is divided into hearth, belly, waist, chest, throat and other parts from bottom to top, and there is a tap hole at the bottom of the hearth, and there is a slag outlet at the appropriate height above it, but the position of the two mouths is not on the same vertical line.

In the upper part of the hearth, a circle below the lower edge of the hearth is evenly connected to the pipes of the hot blast stove around a number of air vents.

The blast furnace of the Ming Dynasty is naturally not as high-end as the modern one, but it also has the rudiments of the modern blast furnace.

"You and other craftsmen are all from the mainland, and they are used to staying in Luzon." Liu Yu did not ask about the situation of iron smelting first, but asked about the lives of these artisan workers.

Liu Yu looked at the busy workers and craftsmen, all from Foshan, Guangdong, who were specially recruited by Lu Hai for the Ming Ting Iron Works at a high price.

During the Ming and Qing dynasties, Foshan's iron smelting was all over the world.

Known as one of the "four major gatherings in the world", Foshan is famous at home and abroad for its iron-smelting industry.

Naturally, it has the best blacksmith households and workers in the country.

"Back to the adult, we are all Foshan craftsmen, dissatisfied with the Qing court's harsh government and followed Lu Hai to Nanyang, and now in Luzon, the rice coupon is enough for me and a family of five to make a living, if it is not for the kindness of the adult, how can we have today's blessings." Wang Qingbi said respectfully.

"Hmm." Liu Yu nodded, the Ming court can be said to attach great importance to the craftsman, in addition to the annual salary, there is also a year's worth of rice coupons.

"Now my ironworks mostly use charcoal for smelting, right?" Liu Yu asked.

"Lord Hui, there is a lot of wood in Luzon, so I use charcoal." Wang Qing said.

"Then do you think it's better to smelt iron with charcoal, or to smelt iron with coal? If coal and iron smelting are good, I will let the four seas import coal from the mainland. Liu Yu asked.

Coal: In ancient China, there were synonyms such as coal, black gold, black gold, woodcutter, burning stone and mineral charcoal.

Liu Yu knew that later generations mostly used coking coal to make iron, and coking coal came from coal.

In the Ming and Qing dynasties, China already used coal to smelt iron on a large scale.

The "Compendium of Materia Medica" by Li Shizhen, a famous scholar of the Ming Dynasty, once said:

"There are also many places in the mountains to the north and south of the Carboniferous. In the past, people didn't use it, so there were few people who knew it, but now people use salaries to cook and exercise iron and stone, which is great for the benefit of the people. The natives all dig the mountain as a hole, and cross into the ...... of more than ten zhang to take. It can be seen that at the end of the Ming Dynasty, coal was already the main raw material for iron smelting.

"If you go back to your lordship, charcoal and coal have their own advantages and disadvantages." Wang Qing smiled and replied.

"Using coal to smelt iron, the heating is fast, the output is large, and there is more coal on the mainland, but the pig iron produced has many impurities and a brittle texture, which is not as good as charcoal smelting.

Seeing that Liu Yu was a little unconvinced, Wang Qing smiled and continued: "My lord, do you know why the Tang Dynasty has Mo Knife and Tang Knife, but they are all lost in the Song Dynasty?"

"Why?" Liu Yu was also interested.

"That's because in the Han and Tang dynasties, iron smelting was mostly made of charcoal from the Central Plains, and iron was smelted with charcoal, and the impurities of pig iron were very few and the quality was high, so the Central Plains could often make famous knives in the Han and Tang dynasties, but later the wood in the Central Plains was greatly reduced, and coal had to be used to replace charcoal, and coal could be used to smelt iron, and there were too many impurities in pig iron, so it was impossible to make a good knife in the Han and Tang dynasties."

"Adults can know that there are many large trees in Fujian and other places, so charcoal is used for iron smelting in southern Fujian, so the texture of Fujian iron is the best."

After listening to this, Liu Yu suddenly realized, and it is no wonder that Dongying's katana crushed a large number of Chinese swords in the Ming and Qing dynasties.

During the Ming and Qing dynasties, China used coal smelting, and the pig iron smelted out was more impurities, while Dongying mostly used charcoal to smelt iron, after all, Dongying has few people, high forest coverage, and even today it is the world's leading ecological power.

Therefore, there is no shortage of wood in Japan, and charcoal is naturally used to make iron, and the katana made from the iron used is naturally excellent.

Liu Yu vaguely remembers that after he first entered Laoag, the Ming Court repeatedly appointed the Four Seas Chamber of Commerce to go north thousands of miles to import pig iron from Japan, just because Dongying iron was good.

"The quality of iron smelting with charcoal is so good, why is the iron material from the iron smelting plant so scarce now, and the firearms department is not even enough to cast the iron for the cannon." Liu Yu asked with a frown when he heard Wang Qing praise the charcoal smelting.

"Charcoal as an iron smelting material, the cost is too high, the production of a ton of pig iron requires at least two tons of iron ore, 130 kilograms of limestone, seven tons of charcoal, the required wood is even more astronomical, these days the iron ore from the four seas piled up into a hill, the craftsmen are waiting for the four seas to transport large wood in order to burn into charcoal." Wang Qing said with an embarrassed face.

"It turned out to be due to a lack of charcoal." Liu Yu nodded.

The output of coal and iron smelting is high and the Central Plains is rich in coal, so coal was used in the Ming and Qing dynasties, and the continuous supply of coal, coupled with the high heat of coal, naturally made the production capacity of iron smelting high.

Although the quality of the iron smelted is high, the amount of wood and charcoal required is too amazing, and the natural output is low.

During the Ming and Qing dynasties, China had to choose to use coal to smelt iron because of the natural environment, and the quantity went up, but the quality was declining.

On the other hand, if you want to increase production, you must use coal, and if you use coal, you must import it from Chinese mainland or Southeast Asia.

Not to mention the trouble of transportation back and forth, and the source is easy to be cut off by the Qing court.

was stuck in the neck by the Tartar, Liu Yu would never do it.

Now the Ming court can only pursue the quality of iron smelting and ignore the quantity.

There is no choice but to do it, after all, Luzon has more charcoal than coal.

"Since my Mingting Iron Smelting Factory uses charcoal to smelt iron today, then presumably pig iron is much better than that of the mainland, right?" Liu Yu asked again.

"It's natural." Wang Qing smiled.

"Pig iron is brittle and not easy to forge, so it can only be used as an agricultural tool, and if you want to mature iron, you need to flow molten iron from the iron-making furnace to the iron-frying furnace and stir it with willow sticks before it can be turned into wrought iron." Wang Qing said as he pointed to the iron furnace on the side.

The so-called iron furnace is actually the Western furnace.

The only difference is that the mixing furnaces used by Westerners use wrought iron rods or steel rods to smelt and burn the carbon in the pig iron to finally obtain wrought iron.

In the process of firing, the willow sticks will gradually be burned because of the high temperature, and integrated into the pig iron, so that the pig iron is mixed with charcoal, reducing the speed of charcoal, so that the iron frying hand can control the iron content, so as to fry the steel with a charcoal content lower than the pig iron but higher than the wrought iron, which is the fried steel.

It can be said that during this period, China's iron-smelting technology was actually ahead of the West.

It's just that after the Tatars entered the Central Plains, China's iron-smelting technology stopped, and was gradually overtaken by the West.

It's a pity that during the Ming Dynasty, China's steel smelting had reached the top level, but it was still a little bit short, that is, smelting steel into molten steel.

Liu Yu leaned in and looked at the so-called iron furnace.

It was found that the fried iron was semi-solid and paste-like.