Although coal is not suitable for ironmaking, the sulfur contained in coal can cause the hot brittleness of pig iron, making it impossible to forge into shape. But coke is the best material for ironmaking.

Hundreds of years later, this is something that is well known. However, the use of coke for iron making is not an easy task. Coking is very easy, only need to put the coking coal in the ordinary clay brick kiln, under the condition that the furnace is not isolated from the air, with the help of the ignition hole on the side wall of the kiln to manually ignite, the coking coal stacked in the kiln is ignited, and the coal is heated layer by layer by relying on the combustion heat of the coking coal itself, and the hot gas flow formed by the exhaust gas generated by coal combustion and a large number of unburned coal cracking products continues to burn through the fuse channel on the side wall of the kiln chamber, and part of the heat is transferred into the kiln. This process lasts for 8~11 days, until the coke is mature, water is injected from the artificial ignition hole to quench the coke, cold the furnace, and the coke is removed. Coke is produced.

But what is the real problem with coke ironmaking?

The real problem is that coke does not burn as easily as charcoal and coal, and if you want to use coke to make iron, it is necessary to improve the blast facilities and adjust the structure of the furnace to obtain more air. In another world, Abraham Darby of England solved this problem by improving the inner diameter of the blast furnace to make it suitable for coke ironmaking, and installed a new blast facility for the blast furnace. In 1709, the blast furnace was successfully smelted from coke to pig iron.

The success of coke ironmaking was only the beginning of a revolution in the British ironmaking industry, which began to wean itself off wood. Technological innovation in the industrial field was the fundamental factor that led to the Industrial Revolution in Britain in the 18th century, and the first technological innovations that came to mind were the textile machine and the steam engine. But in the eyes of economists, the change from charcoal to coke in the 18th century was no less significant than the invention of the textile machine and the steam engine, and even more far-reaching.

The iron-smelting revolution triggered by coke ironmaking brought prosperity to the iron industry, and at the same time, the British iron-smelting industry quickly concentrated in the Midwest and South Wales coal-producing areas, and drove the British coal mining industry to further prosper. Cheap cast and wrought iron enabled the mass production and application of new power machinery, and enabled iron components to be widely used in engineering and construction instead of wood. Not only that, cheap and high-quality wrought iron has made great development of railway construction possible. The invention of coke ironmaking led to the tremendous development of the steel industry and related industries, and mankind was brought into the "steel age", so that the industrial revolution in Britain was in full swing.

It can be said that it was Darby's invention of coke ironmaking that brought Britain into the Industrial Revolution. Zhu Mingzhong, who graduated from an engineering university, is naturally very aware of this, and of course he is also very aware that the use of coke in the traditional iron-making furnace also needs to be improved.

For this reason, while entrusting the charcoal factory to use the charcoal kiln for burning wood, Zhu Mingzhong carefully studied the iron-making furnace, because there was no time to build an iron-making blast furnace that could provide a higher furnace temperature, so it could only be improved on the basis of the furnace, so that it could use coke for iron-making, which was very similar to the improvement of Abraham Darby in England, which was nothing more than increasing the blast volume of the furnace.

"The key is still the bellows, to increase the air volume ......"

Recalling seeing the piston bellows in the iron factory, the ancient Chinese piston wooden bellows are ingeniously designed, reasonable in structure, simple in production, easy to maintain, reflecting a high level of technology. After the invention of the piston bellows, after the promotion and application of the Song and Yuan dynasties, the wooden fan bellows were completely replaced in the Ming and Qing dynasties, becoming the most important blower equipment, which played a huge role in promoting the development of the ancient metallurgical industry. The piston bellows are due to the realization of a two-stroke blow. It is a leap forward in blower technology; Because of its rigidity and good sealing, it can produce large wind pressure and air volume. Compared with the leather bag and the wooden fan bellows, the work efficiency is greatly improved, and the smelting and casting efficiency is greatly promoted. The ancient Chinese piston bellows were the only double-acting bellows in ancient times, and at least until Wilkinson invented the hydraulic blower in the early 19th century, this type of bellows was the best.

When I think of the bellows in the iron factory, the big ones are pushed and pulled by four or five people at the same time, and even the small ones are pushed and pulled by two or three people at the same time. The efficiency of this kind of human air blast is naturally very average.

"Adding another bellows should be able to solve the problem of air blowing, but it is too wasteful of manpower, and it should be changed to water power, and water power push and pull ......"

In this era when there is no steam engine, water power is undoubtedly the most convenient kinetic energy, after the armory factory began to use hydraulic power to transform the pipe, Dai Cang continued to pay attention to the study of hydraulic utilization, but even so, when seeing Zhu Mingzhong's design with multiple wooden gears to transmit water power, and then borrow water power to push the design of the bellows, he was still impressed by its fine design.

“…… These gears can only be made of wood now, but in the future they can be switched to iron gears, and the waterwheel can also be switched to iron shafts, so that the service life will be longer......"

Now Dai Cang has adapted to some of Zhu Mingzhong's whimsical ideas, although he has a very high talent in mechanics, but almost every time, the strategy can always bring him some inspiration, especially the application of hydraulic power.

"After a little effort, since you can use hydraulic blasting, then this wrought iron stirring furnace can also use hydraulic ......."

Of course, Zhu Mingzhong will not object to Dai Cang's suggestion, he will even take the initiative to put forward some suggestions, and even compared with weapon manufacturing, he hopes that Dai Cang can apply his energy to machinery manufacturing, not just weapons, after all, weapons are only tools, and machinery is fundamental.

Dai Cang's talent in machinery has been fully reflected in the establishment of the weapons factory, especially in the process of introducing water power, and the current weapons factory almost completely relies on water power to build weapons, not only that, but even the grinding of gunpowder in the weapons factory has also been changed to water power. As for making guns and casting cannons, there will be other people in charge. For example, Shi Si and his entourage, who will soon come to Qinghe, and Xu Youzheng can also participate in cannon casting. Thinking of casting cannons, Zhu Mingzhong said naturally.

"Jia Mei, now that the Weapons Factory has begun to manufacture grenades in Qinghe, is the iron shell of this grenade still cast with iron fan?"

Iron mold casting, in this era is not an advanced process, after all, as early as the Qin and Han dynasties have been widely used iron fan casting, in the folk casting farm tools is a large number of iron fan casting, casting grenade shells, natural use of this process, after all, iron mold can be reused thousands of times.

However, although the process of iron mold casting is mature, Zhu Mingzhong, as an engineering student, knows very well that the iron mold is not suitable for casting cannons, and the miraculous iron mold casting cannon that has been blown by some articles, the biggest advantage of the iron mold casting cannon is that the iron mold does not need to be dry, and there is no water vapor, so there is no need to worry about the honeycomb structure when casting, and only need to make a clay core when casting, no matter what the weather is, the cannon can be cast immediately, and a cannon can be made in two or three days.

The iron mold cannon greatly improves the efficiency of the cast cannon, and improves the quality of the cannon compared to the clay mold cannon. But the defects of the iron mold cannon are also very serious. Due to the fast heat conduction of the iron mold and the rapid condensation of the casting, it is easy to obtain white iron. White iron is brittle, and it is impossible to use mechanical boring, and it is not even possible to drill a fire door directly into the gun body. Guns made of white iron will crack during firing, and repeated use will even cause the gun to burst.

Later metallurgical experts conducted metallographic tests on the iron mold guns left over from the Opium War, and the results proved that they were all white cast iron. Although the performance of the iron mold cannon is better than that of most local clay mold guns, it is still far inferior to the sand mold cast guns of the British era.

In this case, Zhu Mingzhong naturally did not choose an iron mold casting cannon with many advantages but more disadvantages, but chose a sand mold casting cannon, he is no stranger to sand mold casting, but in the selection of sand molds, some tests are still needed.

"Last time, I asked you to test the sand mold casting, how is it going now?"

Although he is an engineering student, Zhu Mingzhong almost returned the proportion of casting sand to the teacher, but he only roughly remembered some proportions, so he ordered Dai Cang to conduct experiments in the weapons factory.

"After a little, the factory has used river sand, sawdust, and has carried out many sand fan trial casting, although this sand model is not as convenient as the iron fan, but it is better to make a simple model, and now it has been given several formulas according to the strategy, and the trial production, the effect is very good, and the Qinghe River is close to the Yellow River, the Yellow River sand is very suitable for making sand molds, and the sand used in the mold is almost ......" When Dai Cang said the progress of sand mold casting, Zhu Mingzhong pondered for a moment, and then asked rhetorically.

"Jia Mei, in that case, I don't know if you can use a sand mold to cast the Hongyi cannon!"

This is the fundamental reason why Zhu Mingzhong ordered him to study sand mold casting.

"Casting cannons with sand?"

Looking at the envoy in surprise, although he has applied the sand fan to a variety of weapon casting, and even feels that it has the potential to replace the iron fan casting, but Dai Cang has never thought of using it for casting the Hongyi cannon, at least in his opinion, the casting of the Hongyi cannon itself should use the mud fan, this fixed thought, has always limited his thinking with the people of this era, and now the reminder of the envoy made him suddenly realize.

Since you can cast grenades with an iron fan, and you can also use a sand fan, you can naturally use a clay fan. Then why can't you turn it over and change the Hongyi cannon that can only be cast with clay fan in the past to sand fan and iron fan?

"What Jingluo said is that since this sand fan can be used to cast grenades and axles, it can naturally also be used to cast cannons, and the shell of the grenade cast by Xiaguan Guan Shafan is quite smooth, and there is no need to take months to dry like the mud fan, and there is no worry about water vapor when casting, maybe you can give it a try now......."

Zhu Mingzhong was naturally very clear about the various advantages of the sand fan that Dai Cang talked about, and he deliberately added that he thought of some of the knowledge he had learned about cannon casting.

"Jia Mei, this cannon is not only a sand mold, we can also ......"