Zhu Youxiao, who decided to develop heavy industry in order to adjust the economy of the north, naturally the first thing that came to mind was mining and iron and steel smelting, and the development of iron and steel smelting in the north obviously has comparative advantages.

As a science research monk, although he is not a major in steel smelting, steel smelting is nothing more than a problem of chemical reaction and temperature. The basic blast furnace ironmaking principle is very simple, and Zhu You still understands the structure of the blast furnace.

Soon Zhu Youxiao drew the blast furnace drawings in detail, but there was no steam engine for blasting in these years, so the blast furnace could not be built too big.

In order to explore technology, Zhu Youxiao didn't think about building a big one, and planned to build a small blast furnace first, and then explore the technology first.

At the same time, there are also coking and heat storage technologies. Zhu Youxiao decided to use the soil method to make coke first, and it didn't matter if the pollution was a little bigger. It doesn't matter whether the regenerator has it temporarily, the blast furnace can also be produced with cold air, but the efficiency of using hot air is higher, and with the regenerator, it has the basis for the development of open-hearth steel, so the regenerator should also be studied.

With the blast furnace, the cost of pig iron production can completely explode the private steel plant.

The development of industry focuses on speed.

Without further ado, Zhu Youxiao immediately went to the Royal Military Factory, specially carved out a piece of land on the side, and began to personally supervise the construction of the blast furnace.

The Royal Arsenal was originally located in the suburbs, and the surrounding land was very convenient. At the same time, a number of coking furnaces were built. This kind of earthen kiln is extremely simple to build. Under the condition that the air is not isolated in the kiln, the coking coal stacked in the kiln is ignited with the help of the ignition hole on the side wall of the kiln, and the process lasts for 8~11 days, the coke is matured, and the coke is extinguished by water injection from the artificial ignition hole, cold furnace, and coke.

This is soil coking, the disadvantages are obvious, the pollution is relatively large, the cycle is relatively long, and the coal consumption is relatively high. The advantage is even more obvious, that is, the production technology is extremely simple.

The emperor suddenly wanted to make iron and coke, and lived in the military factory all day, and soon the military factory became heavily guarded.

After Zhu Youxiao worked on it for a few days, he found that it was a bit too cumbersome to develop technology on his own, after all, there were too many technologies to develop.

The idea of cultivating talent has popped up again.

So Zhu Youxiao immediately issued an order to establish the 'Royal Academy of Science and Technology', and posted recruitment notices in the northern provinces, as long as children over 15 years old and under 30 years old, they can sign up for the admission examination of the Royal Academy of Science and Technology, after admission, the college is exempted from tuition, and gives a silver tael as a subsidy every month, and recruits 300 people in the first session.

The development of heavy industry naturally requires a large number of talents, Xu Guangqi and other people who were the first to come into contact with Western mathematics and machinery are indeed talents, but theoretically they are still relatively low-level, and it is better to re-train a large number of talents. In order to cultivate talents, Zhu Youxiao began to compile mathematics, physics and chemistry textbooks.

These textbooks are definitely super weapons that surpass the world for hundreds of years, as long as they use these textbooks to cultivate a group of talents, it is very simple to make an industrial revolution.

Zhu Youxiao handed over the enrollment work to Jinyiwei to do, and the requirements for this enrollment are relatively strict, and they must be 'rooted and miaohong', and only recruit scholars from poor families, and those from wealthy families are not wanted, and those with big clan backgrounds are also not wanted. Because these groups, when faced with problems, often take the lead in considering their own interests, and even if they don't want to, they are likely to be coerced by clan and family forces, and cannot put the interests of the country first.

In terms of admissions questions, that is, some arithmetic questions, the questions are very hierarchical, some are of low difficulty, and some are of high difficulty, which can well see the level of a candidate.

Xu Guangqi heard that the emperor was studying ironmaking in a military factory, and he hurriedly came to join in the fun. The salt industry company has organized a large number of stoves to reclaim salt pans on the mudflats of Bohai Bay, and Xu Guangqi has solved the technical problems, and Lin Jusheng is in charge of management.

The same is true for the agricultural company, how to repair water conservancy and how to plant land, Xu Guangqi has made demonstrations, and the company's technical personnel have basically mastered it.

When he came to the military factory, Xu Guangqi gave the emperor a hand.

At this time, Zhu Youxiao happened to be revising and compiling mathematics, physics and chemistry textbooks, and taught Xu Guangqi some chemistry things by the way.

Most of the iron in nature is stored in iron ore in the oxide form of iron, and blast furnace ironmaking is to extract iron from iron ore by reducing the method.

There is a chemical formula for this reduction process. The blast furnace body is a countercurrent chemical reactor whose main function is to melt solid charges such as coke, iron ore and flux into molten iron at high temperatures. During production, iron ore (including sinter, pellet, lump ore, etc.), fuel (mainly coke) and flux (limestone, dolomite, silica, manganese ore, etc.) are loaded from the top of the blast furnace, and hot air is blown into the tuyere at the lower part of the blast furnace. At high temperatures, coke and combustible injections (such as heavy oil, pulverized coal, etc.) are burned to produce carbon monoxide, hydrogen and solid carbon, which snatch out the oxygen in the iron ore to obtain iron. This process is called the restore process. The reduced molten iron is released from the taphole. Impurities in iron ore and coke combine with the flux added to the furnace to form slag, which is removed from the slag outlet. The gas generated in the reduction process is exported from the top of the furnace, and after dust removal treatment, the heating blast furnace, converter, coke oven, heating furnace, etc. are used as fuel.

The structure of the whole blast furnace is actually very simple, and the blast furnace built by Zhu Youxiao this time is a small blast furnace, designed to be 50 cubic meters, which can be said to be very small, and the amount of work is not large. At the same time, it is equipped with three regenerators, Zhu Youxiao tried to build a very small experiment at the beginning, and the results were unexpectedly smooth, and the blast furnace was equipped with three regenerators according to the pattern, and it was used to supply air to the blast furnace in turn.

Its practical cold air can also be used, but the reaction time is longer, the production efficiency is lower, and the quality of pig iron is not so good.

Xu Guangqi plunged headlong into chemistry, as if he had discovered a treasure, and studied so hard that he almost forgot to sleep and eat.

Xu Guangqi also brought Zhu Youxiao more detailed information on folk iron and steel smelting technology.

"Almost all of the best steel in my Ming Dynasty comes from the south. Because the charcoal required for smelting in the north cannot be guaranteed, it can only be smelted with coal, but the quality of the pig iron smelted is very poor, and if the northern steel is used to make guns, it is very easy to explode. "The phenomenon Xu Guangqi said sounds extremely strange at first glance, but the reality is like this.

The use of coal to smelt steel in the north is not a technological progress, but a last resort. Because the forest resources in the north have been destroyed in large quantities, and many places have been cut down, the forest coverage rate may not be as good as that of China in the 21st century. After all, most of the people in these years used wood for cooking, cooking, and heating, and wood was also used for smelting.

There was no charcoal, so coal was used. At first glance, it seems that it is indeed a technological progress, but the influence of China's high-phosphorus and high-sulfur coal has caused a sharp deterioration in the quality of iron products. In terms of guns, iron pipes containing too much sulfur are prone to bursting, and the safety of the shooter cannot be guaranteed. This is also an important factor in the lag of Chinese artillery behind the West.

So much so that almost all the steel used in the royal military factory at this time was purchased from the south, and it was pig iron smelted from charcoal.

China's pig iron production was technologically ahead of the Europeans, who only surpassed China in the eighteenth century. However, China's iron ore resources are poor and there are many messy impurities, and there is not such a good development environment as the Europeans.

In terms of steel production, China and Europe at this time were not yet able to directly produce molten steel. At this time, China did have crucible smelting technology, but it was not used to make steel, but the 'square furnace' used to make iron used crucible technology, which was semi-open and the temperature was not high enough.

If you can't get the molten steel directly, you can't accurately grasp the proportion of various elements in the steel, and then the quality of the steel is not too stable, the efficiency is too low, and the cost is naturally high.

Technically, compared with the government-run iron and steel plants in the early Ming Dynasty, the technology of private iron and steel plants has made great progress, so as to occupy an advantage in cost, and the market price of Tongguò has been more competitive, and the government-run iron and steel plants have been replaced by private enterprises.

As long as the blast furnace ironmaking technology can be successfully tested, the government-run iron and steel plant will be able to surpass the private iron and steel plant in technology, and it will be a big advantage.