Twilight

Shimen Mountain, the cold wind is bitter, and the fallen leaves are rustling

"Smack."

"Dog minion, grinding."

The whip of the military man was whipped on the coolies, who were stout and thick-haired, and were clearly not Han Chinese.

"My father has allocated 3,000 Hun slaves for my deployment, and the military craftsmen and iron ore are also fully prepared." Ying Yue looked at the man beside her and said.

"The blast furnace can be built today, and the result is just a few days." Li Chen said softly.

"Yo-he, yo-he, yo-he."

The slave had a thumb-thick rope on his shoulder, and a dilapidated wooden cart was tied to the back of the rope. The cart was loaded with a whole cut bluestone strip, and the slaves on the left and right were pushing and pulling.

"Squeak, squeak, squeak."

The wooden wheels crushed the fallen leaves and broken branches all over the ground, and they struggled to make their way in the direction of the stream behind the mountain.

The weapons of the Qin Dynasty were mainly bronze, and the melting point of bronze was lower than that of iron. The iron tools smelted in the shaft furnace where copper ware was smelted were brittle and the output was very small, and they were mostly used to make agricultural tools and kitchen utensils.

Under the guidance of Li Chen, the Shimenshan military camp built a blast furnace.

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

Furnace throat: It mainly plays the role of protecting the furnace lining, rationally distributing materials and limiting the gas ash from being carried out by a large amount of gas, and forms the third distribution of heat flow here.

Furnace body: It mainly plays the role of waste heat, heating, reduction and slag making of the charge. A series of physicochemical changes take place here.

Furnace waist: It plays the role of buffering the upward heat flow. The charge has been partially reduced to slag here, and the air permeability is poor, so the diameter of the furnace waist has a tendency to gradually expand. If the furnace waist is high, it is not easy to be too high, because the material erosion at the furnace waist is serious, so the furnace waist is an important part of the blast furnace.

Furnace belly: It connects the furnace cylinder to the furnace waist. It is large at the top and small at the bottom, and it is also adapting to the needs of increasing the volume of gas and reducing the volume of the charge after it becomes slag iron. The inclination of the belly of the furnace should also be suitable. In order to improve the permeability of the charge here, the belly angle of the furnace also expands, and the belly angle of large and medium-sized blast furnaces is generally between 80 and 82 degrees. In addition, the temperature of the furnace belly is very high, and a large amount of slag is formed, so the slag corrosion is serious, and it is a weak link in the blast furnace part.

Furnace cylinder and furnace bottom: mainly play the role of burning coke and storing slag iron. As the strength of ironmaking increases, so does the diameter of the furnace cylinder. The working environment of the furnace is the harshest. In particular, the temperature in the tuyere area is the highest temperature in the blast furnace, and the lining is not only subject to high temperature, but also by the chemical erosion and erosion of slag iron. The bottom of the furnace is mainly eroded by slag iron, especially molten iron.

Complete blast furnace, 8 meters high, 14 meters in diameter, thin at the top and bottom, thick in the middle. It is waist drum-shaped, there is a flue in the furnace, and the flue varies from three to five, and there is a stone ladder outside the furnace that spreads to the top of the furnace. The inner chamber of the smelting blast furnace is made of bluestone strips, coated with mud seals inside and outside, and has one or more arched door openings for feeding, ignition and slag removal, and there are multiple ventilation furnace passages at the bottom.

"Boss, it's almost enough to seal the stone, and you can start testing the furnace tomorrow." Da Niu was transferred to Shimen Mountain by Li Chen to serve as the technical guide for the construction of the blast furnace.

"The bellows must be checked well, and there must be no problems." Li Chen admonished.

The temperature at which charcoal burns fully is 1,800 degrees, while 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 to continuously blow air from the east, west, north and south.

"Keep an eye on it, it must be done today." Ying Yue instructed the officer beside her.

"Smack, smack, smack."

The soldiers who oversaw the work had their whips twitching more frequently.

Next

In front of the blast furnace, there were three sacrifices and five grains for sacrifice, and after watching the priest's god-like performance, Li Chen opened his mouth and shouted: "Test the furnace." ”

Hun slaves held a half-man basket of iron ore that had been hammered into small pieces. Under today's conditions, there is no way to crush the iron ore, so it can only be knocked into small pieces for the time being, and it will be used.

After spreading the iron ore all over the bottom of the blast furnace, the charcoal is poured over the people and the blast furnace is ignited.

"Whew, whew, whew, whew."

At the moment of ignition, the four slaves who occupied the bellows position pulled up the bellows with a snort. The bellows drive the cyclone to blow into the air duct that has been set aside in advance.

"Woo, woo, woo."

The flames in the furnace rose all at once and rushed to the top of the furnace.

"Brother, look, it's melted, it's melted." The big bull looked at the peephole intently and shouted.

The iron ore in the blast furnace has begun to crack, and the impurities contained in it can no longer withstand the high temperature, but it is still close to melting into molten iron.

"It's not enough, keep increasing the wind." Under Li Chen's command, the slave pulling the bellows twitched more rapidly.

As the temperature inside the furnace gets higher and higher, the iron ore has begun to gradually turn red, slowly melting into a magma-like substance, surging towards the tap hole.

Soon all the charcoal and iron ore in the furnace had been burned out, and all impurities except for molten iron were wiped out under the high temperature. There is no open flame in the furnace except for the extremely high temperature.

"Add quicklime and toner." Under Li Chen's orders, some slaves carried quicklime and toner prepared in advance to the blast furnace.

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

"Zi, zi, zi."

When quicklime and toner came into contact with molten iron, an open flame ignited.

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

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

The added carbon powder will be evenly distributed in the molten iron according to the flow and diffusion of the molten iron, and the molten iron with toner will be added

will be more resilient.

Legend has it that when the craftsman forged the divine weapon, he would sacrifice the furnace with a living person, which is also the reason. The essence of human beings is also a charcoal water compound, and the ashes burned by living people enter the molten iron, which will make the molten iron more resilient, and the weapons cast will be sharper.

After the molten iron has been treated with limestone and charcoal powder, the condensed iron ingots can already be regarded as wrought iron.

"Open the sluice gates and release the molten iron." With Li Chen's order, the tap hole of the blast furnace was opened, and the reddish molten iron flowed into the prepared glycoside pot, waiting to condense into iron ingots.

"The iron is out." As a princess, Ying Yue watched from a distance and whispered softly.

This is an iron ingot that has a deep meaning for Great Qin, and it is thought to be the end of the Bronze Age of Great Qin.

Iron is cheaper than bronze, and bronze is much denser than iron, which means that bronze is heavier for the same volume.

Hardness and toughness are two important factors in determining the strength of weapons, but hardness and toughness are often contradictory. At the same hardness, steel is much tougher than bronze.

This is also why the sword, the main weapon equipped by the Qin army, was too fragile to be chopped, so it could only be used for stabbing.

Compared to steel, bronze is more expensive, more fragile, and more bulky. There is nothing good about it except that it looks good.

"Open the furnace."

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

This means the progress of Great Qin from the Bronze Age to the Iron Age, which thought that the battlefield would be transformed from a sword-based stabbing battlefield to a knife-based slashing battlefield.