Late autumn

Shimen Mountain, the cold wind is shrill, the fallen leaves are rustling

"Bang."

"Dog slave, he's slow."

The military man's whip was whipping on the coolie. These coolie were thick and thick in size, obviously not Han people.

"The father assigned three thousand Hun slaves for me to allocate, and the military craftsmen and iron ore were also prepared." Ying Yue said to the man beside him.

"Today the blast furnace can be built, but it's been in these few days." Li Chen said softly.

"Yohe, Yohe, Yohe."

The slave pulled a small rope as thick as a thumb on his shoulder, and a worn wooden cart was tied behind the small rope. The cart was loaded with a completely cut bluestone strip, and the slaves on both sides were pushing and pulling.

"Crack, creak, creak."

The wooden wheels crushed the fallen leaves and branches all over the ground, and walked hard towards the stream behind the mountain.

The Qin Dynasty weapons were mainly bronze ware, and the melting point of bronze was lower than that of iron ware. The iron ware refined with a vertical furnace that refines bronze ware is very brittle and has very little output, so it is mostly used to make agricultural tools and kitchen utensils.

Under the guidance of Li Chen, a blast furnace was built in the Shimenshan Army.

The structure of a blast furnace is mainly composed of five parts: the throat, furnace body, furnace waist, furnace belly, and furnace cylinder.

Furnace throat: mainly plays the role of protecting the furnace lining, reasonable fabric and limiting the large amount of gas ash being carried out by gas, forming three distributions of heat flow here.

Furnace body: mainly plays the role of waste heat, heating, reduction and slag production of the furnace material. A series of physical and chemical changes have occurred here.

Furnace waist: plays a role in buffering upward heat flow. The furnace material has been partially reduced to slag, and the breathability is poor, so the diameter of the furnace waist is gradually expanding. The furnace waist is not easy to be too high, because the materials at the furnace waist are severely washed, so the furnace waist is an important part of the blast furnace.

The furnace belly: connects the furnace cylinder and the furnace waist. It is large and small at the top, which is also suitable for the need for the increase in the volume of gas and the volume reduction after the furnace material becomes slag iron. The inclination of the furnace belly should also be appropriate. In order to improve the air permeability of the furnace material here, the furnace belly angle also expands. Generally, the furnace belly angle of large and medium-sized blast furnaces is between 80-82 degrees. In addition, the temperature in the furnace belly is very high and a large amount of slag is formed, so the slag corrosion is serious, which is a weak link in the blast furnace area.

Hearth cylinder and furnace bottom: mainly plays the role of burning coke and storing slag iron. As the strength of iron smelting increases, the diameter of the furnace cylinder is also expanding. The working environment of the furnace cylinder is the most harsh. In particular, the temperature in the air outlet area is the highest in the blast furnace. In addition to being affected by high temperature, the inner lining is also chemically eroded and eroded by slag iron. The furnace bottom mainly receives slag iron, especially molten iron.

The complete blast furnace is 8 meters high and 14 meters in diameter, thin at the top and bottom, thick at the middle. It is a waist drum-shaped shape. There are flues in the furnace, with three to five flues ranging from three to five. There are stone stairs outside the furnace to spread to the top of the furnace. The inner chamber of the smelting blast furnace is made of bluestone strips, and mud seals are coated on the inside and outside, and one or more arched door openings are opened for feeding, ignition, and slag cleaning. There are multiple ventilation furnace channels at the bottom.

"Boss, it's almost time to seal a stone, and the test furnace will start tomorrow." Daniu was transferred to Shimenshan by Li Chen to serve as the technical guide for the construction of the blast furnace.

"You must check the bellows and never have any problems." Li Chen reminded.

The temperature of charcoal burning is 1,800 degrees, and the melting point of iron ore is 1,500 degrees. In order to ensure that the iron ore can be fully melted into molten iron, Li Chen installed four sets of bellows on each blast furnace, and the air is continuously blown from four directions, east, west, south, and north.

"Keep it in a close eye, the construction must be completed today." Ying Yue ordered the officer beside him.

"Ba, bha, bha."

The soldiers who supervised the workers twitched more frequently.

The next day

There were three animals and five grains for sacrifice in front of the blast furnace. After watching the priest perform like a god, Li Chen shouted: "Try the furnace."

The Hun slaves were holding a half-man high basket, which contained small pieces of iron ore. Nowadays, there was no way to crush the iron ore, so they could only knock it into small pieces for the time being and use it.

After laying iron ore on the bottom of the blast furnace, pour charcoal into people and ignite the blast furnace.

"Hu, Hu, Hu, Hu, Hu."

At the moment of ignition, four slaves occupying the bellows' position huffed and pulled up the bellows. The bellows drove the whirlwind to blow into the air duct that had been left in advance.

"Woo, woo, woo."

The flames in the furnace suddenly rose up and rushed straight to the top of the furnace.

"Brother, look, it's melted, it's melted." The big bull looked at the peeping hole with his eyes fixed on it and shouted.

The iron ore in the blast furnace has begun to break, and the impurities contained in it can no longer withstand the high temperature, but it is still a little short of the time to melt into molten iron.

"It's not enough, continue to increase the wind." Under Li Chen's instructions, the slave pulling the bellows twitched more quickly.

As the temperature in the furnace gets higher and higher, the iron ore has begun to gradually turn red and slowly melt into magma-like substances, surging and leaving the iron holes.

Soon, the charcoal and iron ore in the furnace were all burned out, and under the high temperature, all impurities were wiped out. Except for the extremely high temperature, there was no open flame in the furnace.

"Add quicklime and toner." Under Li Chen's instructions, a slave brought the quicklime and toner prepared in advance to the blast furnace.

Quicklime is a high-end thing in Daqin. There are very few limestone open-pit mines, and the only production is basically used by some Taoists to refine useless pills. The limestone used to refine steel was "borrowed" by Ying Yue from the large and small temples in Xianyang.

"Si, sizzle, sizzle."

When quicklime and toner came into contact with the molten iron, another fire ignited.

The molten iron that has not been exposed to toner and quicklime just can only be regarded as pig molten iron.

Limestone can make impurities in the molten iron adhere to the limestone, forming oxidized slag, which is easy to clean and facilitates the purity of the molten iron.

The added carbon powder will spread evenly in the molten iron according to the flow of molten iron, and the iron water added with the molten iron

Will be more resilient.

The legendary craftsman will use a living person to sacrifice the furnace when casting magic weapons. This is also the reason. The essence of human beings is also a charcoal compound. The burned ashes of living people enter the molten iron, which will make the molten iron more resilient and the cast weapons will be sharper.

The iron condensed with limestone and charcoal powder can be regarded as cooked iron.

"Open the gate and release the iron." With Li Chen's order, the iron outlet of the blast furnace was opened, and the red iron flowed into the prepared glycoside pot, waiting to condense into iron ingots.

"It's out." Ying Yue, as a princess, looked from afar and whispered softly.

This is an iron ingot with profound meaning to the Qin Dynasty, which is thought to be the end of the Bronze Age of the Qin Dynasty.

Iron is cheaper than bronze, and the density of bronze is much greater than that of iron, which also means that bronze under the same volume is heavier.

Hardness and toughness are two important factors that determine the strength of a weapon, but hardness and toughness are often contradictory. Under the same hardness, the toughness of steel is much greater than that of bronze.

This is why the sword, the main weapon equipped by the Qin army, was too fragile to chop, so it could only be used to stab.

Compared with steel, bronze is more expensive, more fragile and more bulky. It has no advantages except being good-looking.

“Open the furnace.”

"Open the furnace." Li Chen's voice echoed in the valley.
Chapter completed!