What causes yellow smoke to be emitted during the quenching of slag and water in lead paste grid production using a blast furnace?/
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At my current factory, we have three oxygen-enriched side-blown furnaces (which are essentially blast furnaces) used for lead smelting. The main raw materials are lead paste and grid materials obtained from recycled lead-acid batteries, with coke being used for reduction. The lead content in the output is over 98%, while the lead content in the slag is below 1.5%. Initially, it was planned to carry out direct water quenching of the smelting slag, and then have it delivered by truck. However, since the problem of yellow smoke arising during water quenching could not be resolved, it was necessary to use a slag casting machine, which required significant additional investment. I would like to ask everyone: What is it in the slag produced from lead paste grid production using a blast furnace that reacts when exposed to water, resulting in the emission of yellow smoke?
I think your company is focusing on the wrong thing; how did you determine that the yellow smoke was caused by the lead paste? Has the composition of your slag been analyzed in detail? Where is your company located? There are still 3 blast furnaces left, which are even more powerful than ours.
Actually, the water slag from our factory also emits yellow or black smoke. It should be similar to yours
The company’s address is located in a large **-grade recycled lead circular economy base in the central region. The designed production capacity is 360 kt/a; it was put into operation at the beginning of this year, with an expected annual output of 200 kt. It’s probably a problem with the lead paste; when it contains high levels of acid, smoking occurs very severely. At the same time, detonations occur occasionally during the water quenching process, which is likely due to incomplete reactions inside the furnace resulting in unreacted material. The boss didn’t really care at first, but there are two major problems: firstly, the workers in charge of the slag discharge area are greatly affected and unable to carry out their tasks; secondly, environmental monitoring readings will also exceed the limits (they’re always above the limit anyway, but it can’t be too obvious). In the slag, there is some iron, silicon, calcium, and lead – all of which are normal. Phase analysis has never been done. Currently, a large amount of blast furnace flue ash is used in the processing of lead paste and lead grids.
Due to smoking, the last two furnaces gave up water quenching and were replaced with slag casting machines, which required significant additional investment; they also broke down frequently, and whenever a furnace stopped operating, these machines had to stop as well.
The slag casting machine shouldn’t break down frequently, right? At the several companies where I used to work, the slag casting machines could last for a long time, provided they were regularly maintained.
It’s a new factory; the workers haven’t been trained yet, management is rather chaotic, and equipment maintenance is inadequate.
Lead paste contains sulfur, which exists in the form of lead sulfate; during reduction reactions, lead sulfide or other sulfides are formed. When quenched with water, reactions occur that produce gases such as hydrogen sulfide and sulfur dioxide, and when these gases are present in large quantities, an explosion can occur – the same principle as that behind the explosion that happens when molten copper comes into contact with water.
What’s the need for a slag casting machine! I see that some factories use many small slag pots, which is quite good and cheap.
What’s the need for a slag casting machine! I see that some factories use many small slag pots, which is quite good and cheap.
It’s indeed not necessary to use a slag casting machine, but using slag bags won’t solve the problems faced by the people in question. We do use slag bags, and the roaring noise can be eliminated, but the color of the smoke cannot be changed. Our smoke still has the same color at present; we are looking for solutions and need to add wet dust removal along with alkali-based desulfurization treatment.