Magnetic separation of slag from pyrite-based acid production plants
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Our company’s sulfuric acid production facility is capable of producing 100,000 tons per year of sulfuric acid from pyrite. The amount of slag generated each year is 60,000–70,000 tons. At present, the quality of this slag is not high; its iron content ranges from 53% to 57%, and its color is brown or black (with residues of less than 0.5%). The levels of arsenic and fluorine in it are low. Currently, the slag is subjected to magnetic separation or flotation processes to produce iron ore with an iron content of around 70%, while the remaining slag with an iron content of 15–20% is sold to cement factories. Friends at sea who have experience in this area (drawings, photos, flowcharts, documents) are invited to share it. Those whose responses are of practical value to this project will receive a reward of at least 20 wealth points!
Our factory conducted pilot tests in 2005, but the results were not good: the grade improved by 2–4%, with a yield of around 80%.
It turns out that we also had such ideas and conducted medium-scale industrial tests using magnetic separators. But the results were very unsatisfactory. Our slag characteristics: iron content: 45~51%, residual sulfur: 0.8%. However, after magnetic separation, the grade only increased by 2%, and in a few cases it didn’t change at all; magnetic separation had no effect on the grade. I gave up later. Fortunately, our company also has an electrolytic copper plant; the slag produced is now used by that plant, and it yields good results. However, the slag cannot be turned into black slag – it must be turned into red slag in order to be suitable for use in the electrolytic copper plant.