Why is it easy for the furnace to fail (form scabs) after switching to pyrrhotite as the fuel? What is the typical temperature control for the furnace?
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Our company used to roast zinc concentrate, but it had no problems switching to roasting the ore from Yunfu, Guangdong. When burning pyrrhotite nowadays, the furnace often develops scabs and stops functioning; problems arise when the furnace temperature reaches around 980°C. Even when the temperature is kept at 920°C, the slag produced is very coarse (even though the ore fed into the furnace isn’t coarse). What causes this? I would appreciate some guidance from my colleagues!
Keep the ore size between 4-6 mm; the key to solving the problem lies in ore blending. I have also heated pyrrhotite, keeping the temperature below 1020 degrees, and removing the coarse slag regularly; there were basically no major issues.
Agree with the opinion above: increase the bottom pressure appropriately and remove coarse slag regularly.
Pyrrhotite has high hardness, a high sulfur content, and strong baking strength. The requirements for the raw material system are much higher than those for zinc concentrate; therefore, I believe that furnace temperature is just one factor – it’s also necessary to consider the furnace volume and the intensity of roasting. The crushing system needs to be improved, and the screens used before feeding materials into the furnace should be replaced with 3.5X3.5 size ones. The bottom pressure and furnace temperature need to be well controlled; if the bottom pressure becomes unstable and the furnace temperature fails to be maintained, it is necessary to remove the slag promptly or increase the air flow for a short period of time.
I have never burned pyrite, but I believe that in a furnace used for burning zinc concentrate, since the gas flow rate in such furnaces is already low, it is even more necessary to increase the gas flow rate when burning pyrite. Pyrite has a high density, which makes it easy to form cold slag, leading to furnace failure
Based on my experience, the particle size of the ore fed into the furnace should be uniform in order to maintain stable pressure at the furnace bottom. It’s also important to determine where scorching starts to occur; it usually happens near the feeding point. As long as it’s not due to high-temperature scorching, there’s no major problem. Our factory’s furnace has an area of 14.4 square meters, and it’s normal for the temperature in the boiling layer to range between 20 and 1000 degrees throughout the year, without this affecting the burning efficiency
We also burn pyrrhotite, but scabs form at the ten exits; we don’t know why