Due to certain factors, the flotation process undergoes drastic changes, leading to abnormal froth layer thickness and froth scraping volume. This can manifest in two extremes: one is a slurry level drop with no froth scraped out; the other is a large amount of slurry and froth overflowing, a phenomenon known as “flood overflow.” The former is caused by excessively coarse grinding, a sudden increase in throughput, excessive flotation concentration, insufficient frother dosage, or changes in the properties of the raw ore. Remedies include adjusting grinding and classification operations, reducing the amount of ore (or adding water), appropriately increasing the amount of frother, and adjusting the reagent formulation. The latter is caused by reduced throughput, decreased flotation concentration, excessive water addition, increased circulation, excessive flotation reagents, increased slime in the raw ore, or leakage of lubricating oil into the slurry. Remedies include reducing the amount of feed water, reducing the amount of middlings, reducing or stopping reagent use.
When such an emergency occurs, a significant temporary adjustment can be made by regulating the gate. Subsequently, the true cause of the anomaly should be analyzed immediately, and the problem should be addressed fundamentally.