It's time for the exciting science popularization session again.

Today I will talk to you about the metal industry, gold, silver, copper, iron, and steel.

How did the Stone Age, the Bronze Age, and the Iron Age come to be?

This mainly comes from man's pursuit of hard materials.

The Stone Age is very well understood, that is, the use of solid rock to make stone spears, stone axes, the main purpose is to hunt, but in the Stone Age, how to process a qualified stone spear, first of all, there must be a solid stone hammer and stone chisel, hammer and chisel must be harder than the spearhead, so that the spear will not be smashed out, the hammer will be broken.

On this basis, the metal was discovered.

Metal-containing ores are naturally harder than ordinary stones, so copper was discovered.

Because copper and iron are not the same, iron ore cannot be formed naturally in nature, but copper and gold can, first of all, pure copper was found and used to make hard copper hammers, copper chisels.

Then gold and silver were also discovered.

Gold, silver and copper, these three metals can form a large piece independently, such as the aforementioned dog's head gold and natural copper blocks.

These are all elemental metals.

Thus the status of gold and silver was established.

Precious metals form the most precious things.

Then learned to use fire, entered the pottery age, human beings found that clay can be turned into pottery after high temperature firing, learned the most basic smelting technology, the next step began to smelt copper ore, remove the impurities in the copper ore, smelt and cast small pieces of copper, but the hardness of copper is not enough, so tin ore and copper ore are smelted together to obtain a harder bronze.

It entered the Bronze Age.

But in the early Bronze Age, there was no iron, it was a problem of smelting technology, the melting point of copper and gold only needed about 1000 degrees Celsius, but iron needed about 1500 degrees, even if people discovered iron ore very early, but the temperature could not be improved, and it could not be refined.

Man's use of iron comes from meteorites.

Meteorites with high iron content, after passing through the atmosphere, burn rapidly, smelt pure iron in the process of falling, Egyptian pharaoh Tutankhamun's tomb, there was a meteorite dagger, because it can not be refined independently, so meteorite is the most valuable thing in the world for a period of time.

Then around 1300 AD, the Hittite Empire in the two river valleys, in the confrontation with Egypt, they were the first country in the world to use coal, coal burning must be much stronger than firewood, on this basis, and with grass ash and quartz sand to invent refractory bricks, plus blowers, finally the furnace temperature reached the demand for ironmaking, the original purpose, was to refine meteorite iron for the king, and finally succeeded.

and pioneered the smelting of iron ore, and finally got iron.

And with the help of iron tools, he built the most powerful army in the world at that time.

The use of coal helped history enter the Iron Age.

And China is a little later, about in the Spring and Autumn Period, pig iron smelting began to appear, large-scale application until the Eastern Han Dynasty, here is a key knowledge point, why does iron need to be beaten repeatedly?

Because iron has a characteristic, it does not exist as a single element on earth.

So what is elemental existence? Pure copper, pure gold, natural copper, natural gold, this kind of thing is elemental existence.

You will never find a piece of natural pure iron other than meteoric iron.

It has to be smelted.

And the ancient people to smelt a piece of iron, how difficult it is, this is a rather long process, first of all, the temperature, the craftsmen of the Spring and Autumn Period, in order to improve the temperature of combustion, first invented charcoal, the firewood and then covered with sand, smoldering, to get high-quality charcoal, and then when making the furnace is also a painstaking brain, first need to screen the most delicate soil, take it to repeatedly filter, kneading, to get the most delicate fine soil, when the fine soil makes the furnace, but also add a certain proportion of rice stalks, plant ash, after burning, so that the mud kiln has a certain air permeability, so that the furnace will not explode due to thermal expansion and contraction。

With high-quality charcoal and a high-temperature resistant furnace, it's time for the minerals.

The ore should be carefully ground into ore, and then the iron in the ore should be selected with a magnet to make a fine material, and then co-solvents such as limestone should be added and put into the furnace for calcination.

A blower is also added under the stove.

And this process usually lasts for two or three days, like burning glass with river sand, and finally burns off impurities to get a sponge-like thing, sponge iron.

But this is not pure iron, there are still a lot of impurities in it, there are many trace elements, such as carbon, sulfur, phosphorus, silicon, manganese, tungsten, vanadium, nickel and other chemical elements.

Some of them are advantageous and some are harmful, such as carbon increases the hardness of iron, nickel resists oxidation and does not rust, and tungsten increases the hardness and sharpness of swords.

Phosphorus and sulfur are two harmful elements, which can make the surface of iron uneven and form bubbles, so these impurities must be removed.

It needs to be heated and beaten repeatedly to smelt out the impurities.

This is the concept of forging.

The so-called 100 steel, 100 steel, that's what it means.

However, due to the low technology of the past, the quality of iron cannot be accurately controlled, and it happens that this batch of ores contains nickel or tungsten, and the weapons made of this batch of iron will be exceptionally good.

And it just so happens that another batch of ore, without these elements, the quality will be inferior.

So it's all a matter of luck.

In the Eastern Han Dynasty, Cao Cao made 5 hundred steel knives, used more than 300 people, spent more than three months, called 100 knives, respectively named Qinglong, White Tiger, Vermilion Bird, Xuanwu, Xiong Gang, is caused by the method of 100 steel, the quality of this batch of knives is particularly good.

And correspondingly, Liu Bei also made the eight swords of Shu, the names are called the East Pole, the West Pole, the South Pole, the North Pole, Buzhou, Fangtu, Bomu, and the horse, Liu Bei used one himself, and the others were given to King Liang, King Lu, Liu Chan, Zhuge Liang, Guan Yu, Zhao Yun, Zhang Fei, called the Eight Divine Soldiers of Shu.

Seven of the swords were lost in the war, but Zhao Yunjian was the only one that survived.

At the end of the Qing Dynasty, the dictatorship of the Empress Dowager Cixi, she was actually an iron fan of Zhao Yun, and she liked to listen to Zhao Yun's drama the most in her life.

In 1928, when the warlord Sun Dianying was digging up Dongling, he dug it up again.

Shu has eight swords, and then in Eastern Wu, Sun Quan also made Wu six swords, white rainbow, purple electricity, evil spirits, meteors, Qingying, and Baili.

However, on the same stage, Shu Bajian and Wu Liujian were all cut off by the Hundred Refining Knife.

The inability to accurately control the elements has achieved the pinnacle of 100 steelmaking in this period, and many famous weapons have been produced, such as the Yitian Sword, the Qinghong Sword, the Seven Star Treasure Knife, the Qinglong Yanyue Knife, the Fang Tian Painting Halberd, the Zhangba Snake Spear, the Gentian Bright Silver Spear, etc., are among the best.

It can also be described as full of secondary two atmosphere.

In modern times, the casting method of steel has been very systematic.

The production process has also changed a lot and become more systematic.

In the first step of the process, there are two units, the coking plant and the sintering plant.

The coking plant is responsible for smoldering coal and processing it into coke for better combustion.

The sintering plant is responsible for crushing the mined iron ore into slag to obtain iron ore, but the iron ore at this time has a very low iron content, and it needs to be further processed to add limestone, calcium carbonate and other co-solvents to the ore and burn it into pellets, or sinter, and turn the raw meal into mature material.

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