China Nonferrous Metallurgy

The increasing use of copper sulfide ore with high fluorine content as raw material for smelting has caused higher F concentration in the smelting off-gas, forming high-F sulfuric acid, which leads to process index fluctuation and equipment failure. To tackle the problem of F removal from acid-making system, a smelter carried out analysis on the F distribution in F removal process and F removal principles, and finally determined rationale solutions, which include controlling the F content in the feed concentrate below 0.05% whenever possible, strengthening the daily maintenance of the primary high-efficiency scrubber to guarantee purification efficiency, adding appropriate amount of diluted sodium silicate at an even speed, etc. By adopting the above-mentioned measures, the off-gas from the primary scrubber enters ESP for further purification, the purified off-gas can completely meet the standard with F≤0.3mg/Nm³, As≤0.05mg/ Nm³, acid mist concentration ≤5mg/Nm³ and dust content ≤2mg/Nm³. It has no effect on the equipment and operation index of the subsequent process. In later monthly repairs and cold repairs of the system, no large-area corrosion, collapse and damage of equipment are found, which proves the F in the acid-making system of the copper smelter has been controlled effectively.