I took out some charcoal. We usually smoke and grill food with firewood, but today we have to have a real barbecue.

Only food grilled over pure charcoal can be considered true barbecue. No matter how you grill with firewood, it will always have a smoky smell, but charcoal doesn't have this problem.

Today's only fresh ingredients were fish, and I chose a large one to grill over charcoal. As for the rest of the wild vegetables, I put them in a bamboo pot and cooked them together with some dried fish.

Soon, the fragrant grilled fish was ready. Eating fish grilled with pure charcoal, besides the absence of smoke, evoked a feeling that can only be experienced in civilized society.

That's the smell of money. Although I didn't buy the charcoal or the fish, the charcoal was indeed more precious than the firewood.

Sometimes people are like that. The same dish, prepared the same way, but with a few different variations and a little more money, will make you feel that it tastes much better than before.

After dinner, I took out all the charcoal. I roughly estimated that there were about twenty or thirty pounds of charcoal, which should be enough for one copper smelting operation tomorrow.

I need to go to bed early tonight. The thought of smelting copper tomorrow, and maybe even forging a copper knife from it, fills me with excitement.

The next morning, I got up early and went to the shed. There were still some things to do today, and I couldn't waste this pile of good charcoal.

Adhering to the principle of squeezing the raw materials to their limit, I mixed the clay with some sand and calcined clam shell powder to make some crooked bowls and cups.

I plan to place these on the top layer of the ore for firing. This way, it won't affect the ore refining process, it won't waste firepower, and it will also allow me to fire a few pieces of pottery for use.

I had already roughly burned those ores once with a fire beforehand, which made the stones more brittle and easier for me to crush them into powder.

By now, the stones had turned into relatively fine stone powder, which I put into a large basket. I estimate the weight to be around three or four hundred pounds.

The finer the stone powder, the larger the contact area between it and the charcoal in the fire, and the easier the reaction will be.

I feel very confident that I will succeed today.

With excitement, I began to lay coarse charcoal on the first layer of the stove bridge, and then put some dry thatch inside as a layer.

The advantage of doing this is that it prevents fine stone powder from falling directly into the firebox below.

Next, a layer of finer charcoal is laid down to increase the contact area between the charcoal and the stone powder, and finally, a layer of stone powder is laid down.

I repeated this process countless times until there was almost no stone powder left in the basket, at which point I poured the rest onto the charcoal.

After spreading the stone powder, there was still some space left, so I started putting those hand-molded things into it, and then covered them with another thick layer of charcoal.

After going through the whole process, almost all of the charcoal from yesterday's batch was used up. But I don't mind wasting the charcoal; as long as copper can be extracted, it's all worth it.

I lit the fire in the firebox as before. But this time, unlike when I was making charcoal, I didn't put the lid on.

This time, the fire below and the charcoal fire in the kiln need to be lit together to achieve a higher temperature in the specific space. I even made a fan for this purpose.

As the charcoal at the bottom was lit, a thick plume of smoke began to rise from the kiln, and soon wisps of blue smoke could be seen rising from between the charcoal pieces.

Seeing this, I increased the speed of my fanning. The fire in the furnace roared and blazed brightly as I fanned it.

But I soon discovered a huge problem.

I've been burning this fire for almost three hours, but all I see is smoke. The temperature of the flames is only at the bottom layer; the areas above are only slightly warm.

My heart skipped a beat. Could it be that things are going to go wrong today?

There must be a reason for this. After three hours of firing, the fire still hasn't come up. Something must be wrong.

I started analyzing the problem, and suddenly a possibility occurred to me. Could it be that too much was added, and the stone dust was blocking the flames from rising, causing the problem?

After much thought, this was the only plausible explanation. Fortunately, the charcoal above hadn't caught fire yet, so I still had a chance to salvage the situation!

I immediately brought the fire out, and then took out the charcoal layer, the clay bowl, and the stone powder inside.

When I removed the stone powder to the last layer, I found that, just as I had thought, the stone powder was so fine that it directly blocked the charcoal fire from rising further, and the flames only burned on the bottom layer.

This won't do. After thinking it over carefully, I decided to change the way the stone powder was laid. But before that, I realized a fatal problem: the kiln was too long, and the charcoal in the middle might not get enough oxygen to burn.

I'm a bit confused right now. If that's the case, then the overall temperature won't rise to a suitable level at all. How can we smelt copper?

I paced back and forth in the shed, biting my fingers, determined to come up with a suitable structure to solve this problem.

After walking back and forth for several dozen steps, I focused my attention on that inconspicuous flue return pipe.

After a moment's thought, I realized that I might be able to mimic this structure to create a ventilation duct.

If...that's the case...

I think I've come up with a better idea. Perhaps I won't even need to fan the fire myself. This furnace can pump in a lot of air on its own!

With this in mind, I no longer hesitated and quickly started working on the ventilation duct system connecting the bottom and top of the furnace bridge according to my ideas.

My idea is simple: since that's the case, let's just do it like making a flue gas collection pipe, inserting a vertical pipe from the center straight to the bottom of the furnace bridge.

Then, branching pipes like tree branches are made along this main pipe. Each layer is filled with a mixture of charcoal and stone powder, sandwiching these branch and main pipes within it, extending all the way to the top.

Following the plan, I began weaving a cylindrical structure from bamboo strips, and after finishing, I covered it with mud. To increase its ventilation, I also poked many holes in it with my fingers.

In this way, I essentially have an indirect chimney. Not only can water be siphoned, but fire can too.

When the hot airflow increases unilaterally, a thermal negative pressure zone will be formed inside, so that the airflow will continuously flow into the hot interior of the furnace through the fuel inlet where the atmospheric pressure is greater.

I just need to block the fuel inlet a little smaller with mud, and the incoming air speed will become even faster, which is no different from a fire-powered negative pressure blower.