Study On Differentiated Oxidation Depression Mechanism Of Cu-Mo Sulfide Minerals

Copper-molybdenum ore has complex mineral composition,with many associated minerals and low grade,making it difficult to recover and utilize.The traditional process of"copper-molybdenum separation by depression of copper sulfide"has always used a large amount of sodium sulfide as a copper depressant,resulting in high costs and serious environmental pollution.Therefore,environmentally friendly and efficient copper depressants have always been the research focus of mineral processing workers.In this paper,chalcopyrite and molybdenite are taken as research objects,and the effects of different collectors and depressants on the flotation behavior of minerals are explored through flotation tests.The mechanism of the agents on the surface of minerals is studied by contact angle,infrared spectroscopy,X-ray photoelectron spectroscopy and Electron paramagnetic resonance spectroscopy.The main findings are as follows:The flotation tests of pure minerals show that the flotation behavior of chalcopyrite and molybdenite under different collector systems shows that kerosene has better selectivity than butyl xanthate,kerosene is more suitable to be selected as the collector of molybdenite.The research on the flotation behavior of chalcopyrite and molybdenite under different depressant systems show that the depressant S₂O₈^2-+Mⁿ⁺（persulfate and transition metal ions）has the best effect.When p H is 8,the amount of S₂O₈^2-is 200 mg/L,and the amount of Mⁿ⁺is 150 mg/L,the recovery of molybdenite obtained is 94.98%,while the recovery of chalcopyrite is only 15.83%.In the artificial mixed minerals tests,under low alkali conditions,a lower amount of S₂O₈^2-+Mⁿ⁺can achieve certain separation of the two minerals.The actual ore flotation tests show that when the depressants S₂O₈^2-+Mⁿ⁺is used in the roughing test of flotation separation of copper-molybdenum mixed concentrate,and sodium sulfide is used as the depressant in the subsequent cleaning,molybdenum concentrate with a molybdenum grade of 43.77%,including 0.45%Cu and 69.10%Mo recovery rate can be obtained.When sodium sulfide is used as depressant in the whole process of circuit,molybdenum concentrate with molybdenum grade of 48.32%,copper content of 0.92%and molybdenum recovery of 40.42%can be obtained.The depressant reduces the use of sodium sulfide in the separation of copper and molybdenum,which has certain practical significance.The contact angle test results show that the treatment of depressant S₂O₈^2–and Mⁿ⁺significantly reduces the contact angle of chalcopyrite,while the contact angle of molybdenite slightly decreases,but the addition of kerosene increases the contact angle of molybdenite.The surface wettability of minerals treated with depressant and collector has changed,which makes the difference between the two minerals in floatability obvious,providing favorable conditions for subsequent flotation separation.The results of infrared spectrum and XPS show that after the treatment of S₂O₈^2–and Mⁿ⁺,the infrared spectrum of chalcopyrite has shifted and a new peak has appeared.After the treatment of kerosene,the characteristic peak of kerosene has been detected on the surface of molybdenite,indicating that the depressant S₂O₈^2-and Mⁿ⁺has adsorbed on the surface of chalcopyrite.The treatment of S₂O₈^2-and Mⁿ⁺leads to the dissolution of Cu and S elements on the surface of chalcopyrite,while the content of Fe element on the surface increases,forming an oxide/hydroxide and iron sulfate surface rich in iron.The content of Mo and S elements on the surface of molybdenite changes slightly,and kerosene could still be adsorbed on the surface to make it hydrophobic and float.The EPR results show that·OH and SO₄-·can be detected in chalcopyrite and molybdenite systems,indicating that the addition of S₂O₈^2–and Mⁿ⁺in the two mineral solutions constitutes an advanced oxidation system.However,the reason for the more serious oxidation of chalcopyrite may be the difference in the properties of the two minerals.Chalcopyrite is easier to be oxidized and the oxidation rate is faster than molybdenite.