Mechanism Of Pyrites Depression And Activation Flotation In High Alkali Environment

High consumption of agent,Severe corrosion of equipment and environmental pollution occurred in traditional pyrites flotation which uses sulfide acid as a activator.It is also very much needed to develop pyrites flotation activator and technology without pollution.In order to investigate the depression mechanism of high-alkaline AC impedance,cyclic voltammetry techniques and the thermodynamic calculation were undertaken.The results illustrated that pyrites surface potential would lead to be lower in high alkaline environment which results in producing hydrophile further;such as Fe(OH)₃,SO₄^2-.Electrochemistry experiments showed that pyrite surface Faraday reaction resistance(Rp) decreased in the high alkaline environment of the,while the hydrophile further adsorbing on pyrites surface led to surface resistance(Rs) increasing.The value of Rs in lime system was larger than in NaOH system for adsorption of calcium membrane on pyrites surfaces,which was the reason that lime had stronger depression effect on the pyrite flotation than NaOH.Single mineral flotation was adopted to study the activative effects and mechanisms of four agents including sulphuric acid,oxalic acid,copper sulfate and ferrous sulfate alone or in combination.The results showed that both sulphuric acid and oxalic acid can activate pyrrhotine and the activate effect of oxalic acid is better than sulphuric acid.It could not abtain high recovery by using copper sulfate and ferrous sulfate alone.Although,it could strengthen the activation effect by using acids and sulfate in combination.According to technical and economic factors,new active agents were combination usage of oxalic acid and ferrous sulfate.Flotation in factory proved that the combination usage of oxalic acid and ferrous sulfate could not only solve the problems,but also improve production index.The studies with using thermodynamic calculation and electrochemistry experiments indicated that the activave mechanisms of acids have two facets: the one is to elevate the own surface potential which results in preventing to produce hydrophile further;the other is to wipe off hydropile from the surface of pyrites in order to reveal the fresh surface of mineral,the Rs(surface resistance) of pyrites surface is declined by increasing the dosage of sulphuric acid and oxalic acid and the Rp(faraday resistance) is enhanced by increasing the dosage of sulphuric acid and oxalic acid.The value declining of Rs with using oxalic acid was larger than sulphuric acid for the nice complex ability between oxalic acid and Ca,Fe,which lead to stronger cleansing effect on pyrites surfaces by using oxalic acid.Cyclic voltammetry experiments show that pyrite surface recovering in the lime system with sulfuric acid and oxalic acid increasing.The results is consistent with the results of flotation experiments.