Study On The Influence Of Surface Hydrophobic Modification On Filter Characteristics Of Fine Mineral

With the improvement of mechanization degree of coal mining, the content of fine coal slime tends to increase in coal slime water. The main mineral composition of the fine coal slime is hydrophilic minerals such as quartz and kaolinite. They are very easy to slime, with characteristics of mall particles,large surface area, high surface polarity, strong surface hydration and negatively charged surface and so on,leading to the high product moisture of slime filtering dehydration, so they can bring a series of negative effects to the production and utilization. At present, filter aid are mainly from the angle of particle agglomeration assisted dehydration, without considering particle surface hydration. The paper from the slime mineral particle surface hydrophobic modification to improve slime filtration and dewatering effects and carry out related research, the study can provide theory and technology support for coal slime dewatering.The paper selects the main minerals (quartz, coal) in coal slime water as the research object, studied the effects of three different kinds of hydrophobic modified agent (1# anionic surfactant,2# cationic surfactant,3# nonionic surfactant) on quartz and low ash coal filtration characteristics.And to select the best hydrophobic modification agent, using the single factor optimization experiment,investigating two mineral best medicament filtration dehydration conditions from dosage, stirring time, stirring speed, pulp pH value, particle size and other aspects.And to explore low ash coal and quartz different mixtures (different mixing ratio and different particle size composition, different concentration) on the filtering characteristics of the impact under effecting of the optimal hydrophobic agentAnd verify the filtration conditions of fine particles and several commonly used filter aid agent filtration comparison test by using small DL-5C type vacuum filtration system.Finally, the changes of infrared spectra and the changes of surface wettability of minerals before and after the adsorption of hydrophobic agents were investgated,and combine with the results,analysis the effect of hydrophobic modification on the mineral from the mechanism.The results show that:1) The 2# reagent is best for quartz and low ash coal filtration, within a certain range, fine mineral filter cake moisture decreases with the increase of the dosage of reagents, filtration velocity increases with the increase of the dosage of reagents.Under the effect of 2# reagent, quartz optimum filtration conditions is dosage 200 g/1, stirring time 4 min, stirring speed of 300 r/min, pH value close to the quartz isoelectric point at pH= 2; Low ash coal optimum filtration conditions is dosage of 40 g/t, stirring time 4 min, stirring speed of 300 r/min, pH value at about 6-8. Grain grade 0.074 mm of low ash coal has the greatest effect in the filter,hydrophobic agent for fine granularity of fine coal particle filter to improve the effect is obvious.2) The higher content of quartz, the higher filter cake moisture of mixed system, the slower filtration velocity; The more content of grain grade<0.074 mm,the higher filter cake moisture, the slower filtration velocity; The higher slurry concentration, the less filter cake moisture, filtration velocity but more slowly.3) Using DL-5C type vacuum filter system, of quartz, low ash coal and the mixture of both minerals in without agents and 2# agent the best filter conditions, filtration test results and the suction filter filtration test results are consistent. Compared with the blank test, filter cake decreased by 5.93%,2.25%,3.09%, respectively. Compared with the effect of 2# hydrophobic modification reagent, sodium dodecyl sulfate, polyacrylamide and polymeric aluminum chloride filter aid on the filtration, the effects of the 2# hydrophobic modification agents reduce the filter cake moisture is the most obvious.4) The main filtering mechanism of surfactant is to reduce the surface tension and make the surface hydrophobic. Combined with chemical agent and without medicament two cases, fine mineral infrared spectral analysis test and contact angle test before and after the changes that the hydrophobic agent to join, some degree of adsorption on the surface of the mineral, mineral surface contact angle increases, increases the surface hydrophobicity.