Effect Of Nonionic Surfactants On Adsorption And Flotation Behavior Of Oxidized Coal

In order to improve the surface hydrophobicity of fine-grained coal and improve the effect of flotation,three kinds of non ionic surfactants containing the same hydrophilic head and different hydrophobic tail chains were selected.Twelve alkyl alcohol polyoxyethylene ether(C₁₂EO₁₅),twelve alkyl amine polyoxyethylene ether?AC-1215?,and nonylphenol polyoxyethylene ether(NPEO₁₅).The effects of adsorption time,initial concentration,pH and Ca²⁺strength on the adsorption properties of three non-ionic surfactants on oxidized coal surface were investigated.Combined with adsorption kinetics simulation,FTIR,adsorption quantity measurement,Zeta potential measurement and flotation experiment,the adsorption differences between three surfaces on oxidized coal were compared.The results show that the structure of hydrophobic tail chain has an important influence on the adsorption effect of non-ionic surfactant on oxidized coal surface.The main conclusions of the study are as follows:?1?In the experimental concentration range,the adsorption of three surfactants on oxidized coal increases with time,and the adsorption processes of the three are all in agreement with pseudo-secondary adsorption kinetic models.The adsorption types on the oxidized coal are monolayer adsorption.?2?In the experimental concentration range,with the increase of the initial concentrations of the three solvents,the oxidized coal increased the adsorption amount and the clean coal yield,C₁₂EO₁₅5 could significantly enhance the hydrophobicity of the oxidized coal surface,and the flotation coal yield increased from 49.39%to 84.83%,NPEO₁₅5 second,the highest yield of clean coal up to 81.14%,AC-1215 adsorption effect in general,the highest yield of clean coal up to 58.58%.?3?There is no obvious change in the Zeta potential value of coal surface after the adsorption of C₁₂EO₁₅5 and NPEO₁₅5 on the coal surface,but the Zeta value of the coal particles will increase after the AC-1215 adsorption on the oxidized coal.This phenomenon is caused by the AC-1215 molecules in the water protonation.?4?Analyze the infrared spectra of the three kinds of non-ionic surfactants before and after the adsorption of oxidized coal,and find that the amount of hydrophobic groups on the coal surface increases with the increase of the adsorption capacity of the three on the oxidized coal.The hydrophobic properties of coal are thus enhanced.?5?The adsorption amount and surface potential of three kinds of surfactants in different solution pH were measured and the flotation experiments were performed.The results showed that at the experimental concentration?all50 mg/L?,the acid solution environment could inhibit the adsorption of C₁₂EO₁₅and AC-1215 on oxidized coal,but it has little effect on the adsorption amount of NPEO₁₅.The alkaline solution environment can promote the adsorption of the three on the oxidation of coal,especially AC-1215 adsorption maximum increase.?6?The effect of Ca²⁺ion intensity on the adsorption of three surfactants was studied.It was found that with the increase of Ca²⁺concentration,the adsorption capacity of C₁₂EO₁₅5 on oxidized coal also gradually increased.The adsorption of NPEO₁₅5 on oxidized coal did not change much with the increase of Ca²⁺concentration.The increase of Ca²⁺concentration can significantly enhance the adsorption of AC-1215 on oxidized coal.?7?The adsorption capacity of three kinds of surfactants on kaolinite,quartz and calcium carbonate was determined based on the ash content of oxidized coal after three adsorption.The results showed that the amount of adsorption of the three kinds of minerals on three minerals was:kaolinite>quartz>calcium carbonate,and the adsorption amount of NPEO₁₅5 on minerals was the most.The adsorption selectivity is the worst.C₁₂EO₁₅5 has less adsorption capacity on minerals and better adsorption selectivity.