| This thesis used residues generated from coal-water slurry pressurized gasifier as objects to investigate,comparing and discussing the generated conditions of fine slag and coarse slag.Analyzing various of basic properties of raw coal,fine slag and coarse slag,including particle size,density composition and ash content distribution,mineral composition,organic functional groups,scanning electron microscopy morphology and pore size distribution.Slag samples had lower fixed carbon content compared with that of raw coal,lattice structure defects appeared on regular crystal structure of the minerals which led to amorphous vitreous structure,different kinds of minerals arose occurrence of low temperature melting phenomenon with each other.The phase transition generated other new substances to replace the original minerals,oxidation reaction has increased the quantity and type of organic surface-COOH,-OH,-C=O and other hydrophilic functional groups,pore structure of carbon particles has be changed into medium micropore,specific surface areas of raw coal,coarse slag and fine slag were 8.2821m2/g,183.4502m2/g and 258.2878m2/g,average pore diameters of raw coal,coarse slag and fine slag were 9.4901nm,5.0214nm and 6.1767n.Positive flotation explored single factor experiments about diesel collector,sec-octyl alcohols foaming agent at first,at the conditions of diesel dosage 5000g/t,sec-octyl alcohols dosage 4500g/t could gain clean coal products with flotation refinement index of 0.74%.Dealing exploratory experiments of reagents system after using CaCl2 to adjust the pulp zeta potential from-24.1mv to-0.248mv,that would reduce reagents dosage while flotation refinement index was being improved,to produce clean coal products with flotation refinement index 0.91%under the conditions of diesel dosage 4000g/t,sec-octyl alcohols dosage 3500g/t.After those procedures,drew ultrasonic wave of ultrasonic frequency 40kHz and power 300W into pulp pretreatments,Successively explored the ultrasonic time,dosage of collector and foaming agent,pulp density as well as inflating volume.The best flotation conditions as followed ultrasonic time 4min,diesel dosage 3500g/t,sec-octyl alcohols dosage 2500g/t,pulp density 60g/L,inflating volume 0.3m3/h,products productive yield 7.15%,ash content 55.36%,flotation refinement index could reach to 2.01%.Reverse flotation embarked on separating inorganic minerals as target minerals from pulp.Single factor experiments included carbon inhibitors for β-CD and soluble starch,collectors for CTAB and DDA,foaming agent for 2#oil and sec-octyl alcohols,as well as pulp pH adjustment,reverse flotation efficiency as experimental results indicator system.The optimum reaction conditions are as follows:pulp density 60g/L,rotational speed 1900r/min,inflating volume 0.3m3/h,carbon inhibitors β-CD dosage 800g/t,collector DDA dosage 5500g/t,foaming agent 2#oil 4000g/t,pH=8.3,flotation concentrate yield 17.08%,ash content 83.62%,tail yield 82.92%,ash content 55.27%,reverse flotation efficiency 15.69%.Selected β-CD,2#oil and DDA to commence response surface methodology for optimizing the above three factors-levels conditions.In addition,used Minitab 15 software to analyze the experimental results and represent change rule among reverse flotation efficiency,β-CD,2#oil and DDA.Significance level of three factors was DDA>β-CD>2#oil.The equation has forecast the best reagent conditions:β-CD dosage 823.23g/t,DDA dosage 5587.87g/t,2#oil dosage 3945.46g/t,emerging maximal reverse flotation efficiency would rise to 16.30%.Experiment verification was carried out the practical reverse flotation efficiency was 16.23%,the error was 0.07%.With several kinds of flotation methods to separate and enrich unburned carbon in coal-water slurry pressurized residues was proved to be an effectual way to make segregation between organic burning body and inorganic minerals come true,which conformed to the claim on resource recycle. |
PDF Full Text Request