Liu Tan is quite familiar with honeycomb coal. When he was a child, his family used to burn honeycomb coal for a period of time.

It is not true that this kind of coal is completely smokeless. Ultimately, it depends on the quality of the coal.

His family was poor at that time and used the lowest quality honeycomb coal. It was said to be made from straw and low-quality coal, which could be considered a waste recycling, so there was a little smoke.

As for the more advanced honeycomb coal, it naturally requires anthracite, yellow mud and some other auxiliary materials.

Because the lowest grade honeycomb coal is the easiest to make, and if it is made quickly, it can be used by the people of Shuofang City before winter. It is probably unlikely to be promoted throughout the northern border country. There is not enough time and even less time for transportation. I just hope that it can be fully promoted before next winter.

After Liu Tan asked someone to get some straw, he began to try to make honeycomb coal with it and the low-quality coal. The first step was to crush all of this stuff.

Because there were no machines, they had to be crushed bit by bit by hand. The coal was not a big deal, and I don't know which clever guy directly got a stone mill to grind it. Of course, before using the stone mill, the coal needed to be broken into small pieces so that it could be easily put in.

This is only possible with coal, but not with straw, which must be chopped up bit by bit with a knife.

Liu Tan saw that it would take a long time to finish this process, so he thought about it and decided to make a meat grinder that was very similar to the meat grinders of later generations. He made a round stone trough, and in the middle was a meat grinder made of three curved swords. The middle was left empty for the iron shaft, and there was a frame on top that could be used to pull a donkey or mule.

This will not only free up manpower, but also make the process much faster. As for the wear of the cutting tools, there is nothing you can do about it. Even if you use manual labor, the cutting tools will still wear out.

Liu Tan had made this thing casually and didn't think it was anything special. But when he tried it out, almost everyone in the county government came over, even Huo Guang came to join in the fun.

Liu Tan looked at them helplessly: "There's nothing special about this thing. What are you all doing? Hurry and get back to work!"

After saying the last sentence, he even laughed and felt as if he were possessed by Zhou Baopi.

Few of these people were afraid of him to begin with, and his smile made them even more presumptuous. Li Buyan even stretched his neck and said, "Your Highness, Your Highness, hurry up and make it move."

At this time, the donkeys are already in place. Because a large amount of crushing is required, the crusher is made large, and two donkeys are needed to pull it.

Liu Tan asked someone to put on the lid. For convenience, a round stone slab was used to split the lid in two. When it was put on, it could be completely covered from both sides to prevent the straw fragments inside from splashing out.

However, this method is somewhat rough and the sealing is not very good. Liu Tan estimated that the straw would be splashed out if it was broken.

Before letting anyone start, Liu Tan tried it first. When he opened the lid, he found that the effect was not particularly good.

Huo Guang, who was standing by, saw him frowning and couldn't help but comfort him, "Your Highness, don't worry. Just cut it a few more times and it will be fine."

Liu Tan shook his head: "No, even if we cut a few more times, there will always be some fish that slip through the net. Hmm, let's add another layer of cutting knife."

Fortunately, when he asked someone to make a few more reamers, he was afraid that the reamer would be damaged if something went wrong during the experiment. Now they can be used.

The stone trough itself was very deep, so adding a layer of auger was no problem. Liu Tan simply asked someone to move the lower layer of auger down a little bit, and then separate the blade of the upper auger from the lower one, trying to create a dead angle without any dead angle.

As for fixing, this is very easy. Just make a ridge and a groove on the cylinder between the two reamer blades for passing the bearing, and it can be firmly clamped.

It didn't take much time to add this.

Liu Tan estimated that this time there should be no problem, but the increase in the number of cutters also meant an increase in power. Seeing that these people were still surrounding the pulverizer and refused to leave, he simply left. Before leaving, he said, "You still have to watch, don't regret it."

Huo Guang and the others ignored him, thinking Liu Tan was joking with them. Liu Tan had no choice but to shake his head and leave. Before leaving, he said, "Just show it to me when you're done."

He is busy, how can he have time to stare at this thing?

As a result, after a while, the few people who had just gathered in front of the blender reunited in his study, each covered in straw.

Liu Tan couldn't help laughing at Huo Guang's rare embarrassed look. Huo Guang asked someone to remove the debris from his hair and said unhappily, "Your Highness, did you do this on purpose?"

Otherwise, why would they just let them go back without reminding them that they would be buried by the straw fragments?

Liu Tan did it on purpose, but he didn't expect the effect to be so funny. If the people in Chang'an saw this, how could they believe that these people were the famous young nobles of Chang'an?

Liu Tan said with a smile, "Okay, stop picking them. Go back and take a shower. Let someone get the straw out of your hair. I'll give you half a day off."

Huo Guang stared at Liu Tan for a long time. Just when Liu Tan thought Huo Guang had finally lost his patience with him and was about to hit him, Huo Guang walked over and patted his head hard, rubbed it, and then said nonchalantly: "It seems that Your Highness also needs to go to the bath."

Liu Tan:!!!!!!

Is this human stuff?

He reached out and felt his hands full of straw fragments. He didn't even have time to get angry with Huo Guang and turned around to run to take a shower.

But no matter what, after the problems of straw fragments and coal slag are solved, the next question is how to integrate them.

The most important thing here is the ratio. The straw here plays an ignition role, but the combustion efficiency of straw is definitely not as good as coal, so the proportion of straw cannot be too high, but it must be able to ignite quickly.

Liu Tan initially tried a mixture of 90% coal and 10% straw, and found that although it could be ignited, it ignited very, very slowly.

Finally, he added 20% straw to make the ignition speed barely satisfactory to him. Later, he tried more proportions. Although it ignited quickly and the fire was very strong this time, the burning time was too short, so he still maintained the ratio at 80% coal and 20% straw.

But after he finished it, he found that he had forgotten one thing - desulfurization.

Liu Tan, who traveled through time from the future, understood the importance of protecting the environment. It would take a lot of effort to control it after it was polluted. Not to mention the current soil erosion problem in the Northern Border Country, it is unknown when it will be solved.

Liu Tan didn't have any instruments, and the only thing he knew was the chemistry knowledge he learned in school.

Desulfurization requires slaked lime. Since Liu Tan found the source of limestone, he found that this thing is really useful. He even began to doubt whether the area was enough for him. If not, he would have to keep looking.

After the desulfurization process is completed, and then the honeycomb coal is formed, the surface is treated with paraffin. It should have been treated with heavy oil, but heavy oil is the heavy oil left after gasoline and diesel are extracted from petroleum. Where is the oil these days... He knows it, but there are no conditions for mining, and the easily mined oil is in the Persian Gulf. If he wants to get it, he has to wait and see when Liu Che will get restless and conquer the Western Regions and fight all the way to the Persian Gulf.

However, Liu Tan estimated that this was just a thought and was basically impossible to achieve.

So in the end Liu Tan tried paraffin wax and tung oil, and when he found that they worked, he chose tung oil.

After the honeycomb coal was made, Liu Tan had someone test it. Basically, the burning time could cover the entire night, which was enough, at least it could keep warm.

However, after the honeycomb coal is made, a matching stove is required to divert the smoke outside.

Even though this honeycomb coal is basically smokeless, it is only invisible to the naked eye. When it burns, it will eventually produce some harmful substances. If it is in a confined space, it can easily cause poisoning, so the smoke must be drained out.

Making a honeycomb coal stove is actually not that easy, because it is not enough to just place honeycomb coal inside and let it burn, it also needs to have a certain heating function.

Liu Tan was not unfamiliar with this type of furnace. It was basically composed of the main furnace body, furnace, furnace chamber, coal inlet and chimney.

The furnace is the base for collecting ash. Liu Tan tried hard to recall the shape of the furnace in his home, drew it, and then handed it to the craftsman.

Originally, he thought the matter was over, but when Emperor Liu Che issued an imperial edict, Liu Tan jumped three feet high: "What? Father wants me to go back before the New Year? I thought it was just a casual remark!"

Huo Guang calculated the time and said, "It depends on when Your Highness wants to arrive. If it's a little later, it doesn't matter. There's still time."

Liu Tan was at a loss for words: "If I had known earlier, I would have made another kind of honeycomb briquettes!"

Huo Guang was also surprised: "There is another kind?"

Liu Tan was at a loss for words and said, "That's right. This honeycomb briquettes are made of inferior materials so that ordinary people can afford them. How can we give this stuff to our father?"

It would be fine if Liu Che didn’t know, but if he did know... I’m afraid he would break his legs!

Huo Guang was also a little nervous: "Is it still too late?"

Liu Tan said helplessly: "Let's hurry up and choose a place for processing first, and then we can move forward together."

Originally, he had no plans to go back in his first year in the Northern Border Kingdom, but in order to get him to go back, Emperor Liu Che did not write a letter but directly issued an imperial edict. How could he not go back?

When Huo Guang heard that he wanted to choose a place, he immediately asked someone to get a map. This map was drawn by someone he personally selected. It must be said that Huo Guang had a good eye and the person he selected was quite talented.

However, drawing maps does not require them to have excellent painting skills, as long as they can draw according to the regulations.

Liu Tan looked at the map and found Huo Guang standing next to him, staring at him. He pondered for a while and turned to look at Huo Guang: "What do you think...should I choose a few more places?"

Huo Guang couldn't help but laugh, then quickly suppressed his smile and said, "Your Highness, there's no need to be so deliberate. Just do whatever you want to do."

Huo Guang had analyzed it before. He asked Liu Tan to select more than a dozen places but no mines were found. So he thought that Liu Tan's ability probably could not be sought deliberately.

Liu Tan thought about it and carefully selected three places. He then threw the pen to Huo Guang and said, "One of these three places specializes in honeycomb coal, and one is a paper workshop. I don't believe that all three have mines!"

Huo Guang took the pen and hesitated for a moment before saying, "Your Highness... I don't know whether I should advise you not to say this."

He always felt that what Liu Tan said might come true. If they really did have mines, it would obviously be good news, but their prince would probably cry.

Liu Tan was silent for a while and then said, "Well...what if both of them are true?"

Huo Guang suppressed a smile and said, "Didn't Your Highness choose more than a dozen places before? Just choose one from there."

Liu Tan couldn't help but slap his forehead. "How could I have forgotten those places? No, why didn't you remind me? If I had known, I wouldn't have chosen them!"

Huo Guang decisively put the map away and said, "Your Highness, please choose more places."

After saying this, he turned around and left without giving Liu Tan a chance to leave the map.

Liu Tan looked at his back helplessly, feeling that his skill points seemed a little off.

Others rely on their talents to make a fortune through time travel, but he relies on metaphysics. How come? Damn!

It was also because of this that Liu Tan didn't know whether he should hope for mines in these three places or not.

Huo Guang sent people to investigate the three locations. This time he was smart and sent out craftsmen who were good at identifying raw ores, so as to avoid being overlooked if they failed to recognize them.

The news arrived three days later. At that time, the county government was holding a court meeting. Wei Buyi came in happily and said, "Your Highness, minerals have been discovered in two places!"

I don’t know why, but at that moment Liu Tan was actually relieved - fortunately there was still one piece left that could be used, which was pretty good.

By now he could calmly ask, "What kind of mines are these?"

In fact, he was not the only one who was calm. Everyone else was almost used to it. The only one who was more interested in the type of minerals.

Wei Buyi said, "One is iron ore, and the other is cinnabar!"

After Wei Buyi finished speaking, everyone felt a little regretful for a moment. After being accustomed to very precious minerals such as copper and agate, as well as undiscovered minerals such as coal, iron ore and cinnabar seemed less eye-catching.

Liu Tan looked at everyone who seemed to be reluctant to leave and couldn't help but laugh and cry for a moment. What were those expressions on their faces? Iron ore and cinnabar are both very useful.

In fact, these mines are more useful than agate. After all, agate is a toy for the rich.

"Are you sure there is no mine in the remaining place? If not, let them start construction. There is no time to delay." Liu Tan coughed lightly and changed the subject.

Wei Buyi scratched his head and said, "There aren't any mines, but there are some beautiful stones. I chose one and had it polished and brought it to Your Highness. Doesn't Your Highness like these stones?"

He still remembered that Liu Tan had given stones to Liu Che, and thought that Liu Tan liked them. Little did he know that Liu Tan had no idea what to give him.

Liu Tan originally wanted to explain, but when he saw the dark green and transparent stone handed to him by Wei Buyi, he almost fainted - isn't this a fucking tourmaline?