Study On The Flotation Reagents Treated By Plasma To Enhance Low-rank Coal Flotation

Reducing flotation cost is the key to achieve efficient utilization of low-rank coal slurry.The compound reagent is an important part of the high-efficiency flotation of low-rank coal.It mainly adopts the preparation method of physical compounding.Since the compounded components are mostly fine chemical products,the cost of the flotation agent remains high.It is a new way to prepare low-rank coal flotation reagents by chemical modification method using conventional reagents as raw materials.In this thesis,the effect of plasma treatment on the flotation effect of single reagent and compound reagents were systematically studied by using plasma treatment flotation reagents as the technical idea and conventional flotation reagents dodecane and 2-octanol as raw materials,and the mechanism of plasma treatment flotation reagents to enhance the flotation of low rank coal was explored.The conclusions are as follows.As for dodecane before and after plasma treatment,the combustible matter recovery is only 62.36% when the dosage of untreated dodecane is 24 kg/t,and the flotation effect is poor.With the increased of plasma treatment time,the flotation effect of modified dodecane improves gradually.When the dosage of dodecane(PD)was 6kg/t for 10 min,a good index of the combustible matter recovery of 81.04% and clean coal ash content of 5.07% was obtained.The yield of clean coal increased by 40%compared with that before modification.As for 2-octanol before and after plasma treatment,the yield and the combustible matter recovery of untreated 2-octanol decreased gradually with the increased of reagent dosage,which seriously affected the flotation effect.After plasma treatment for10 min,the combustible matter recovery reached 84.01%,cleaned coal ash content is6.10% when the dosage of PO was 12 kg/t.After plasma treatment,the flotation effect of 2-octanol was improved obviously.The collection performance of combined reagent before and after plasma treatment were reseached.When the mass ratio of 2-octanol to dodecane was 30% and the dosage was 24 kg/t,the combustible matter recovery was 78.31% and the clean coal ash was5.23%.When the mass ratio of the compound reagent was 20%(PC20)and the dosage was 4 kg/t after plasma treatment for 10 min,the combustible matter recovery was88.04% and the ash content of cleaned coal was 5.42%.Comparing with the single reagent treated by plasma,the dosage of reagent can be saved by 2/3.GC-MS,interfacial tension test,laser particle size analysis,XPS test,FTIR test and contact angle test were used to systematically study the effect of plasma treatment on chemical structure modification and the mechanism of chemical and coal slime interaction.When plasma treated single component reagent,the dodecane carbon skeleton structure was broken and recombined,and various types of alkanes and oxygen-containing organic compounds were produced.After the oxidation of 2-octanol,the components are diverse,and the relative content of new alkanes and long-chain alcohols is close to 24%.On the basis of the fracture and oxidation of the carbon framework of dodecane and 2-octanol,a variety of polar long chain organic compounds were also formed by the compound of plasma treatment,in which dodecane was directly grafted with 2-octanol to obtain 2-octyl-1-dodecanol.This indicates that the chemical molecules themselves can not only be oxidized and recombined in the plasma treatment process,but also realize different degree of combination between the two chemical molecules.The proportion of polar long-chain organic compounds in PC20 is more than 10%.Quantum chemical calculation assisted to verify that part of polar longchain organic compounds in PC20 have higher activity and greater adsorption energy with coal model molecules,which effectively improve the adsorption probability and stability of agents,so as to strengthen the collection performance of agents.The interfacial tension value of PC20 in water is the lowest,the droplet size is small,and the dispersion is good,which is conducive to the drug spreading adhesion on the surface of coal particles,thus reducing the dosage of flotation agent.The polar components of PC20 mainly bonded to the hydrophobic water point on the coal surface through hydrogen bond.After acting on the surface of the coal sample,the content of C-C/C-H functional groups increased by 7.41% and the contact angle increased by 36.04°.Therefore,the combined reagent of plasma treatment can effectively improve the surface hydrophobicity of slime,strengthen the flotation effect of low-rank coal,save the flotation agent dosage,and provide theoretical basis for the industrial application of low-rank coal flotation after the modification of traditional reagent.The thesis has 29 figures,23 tables,and 127 references.