| Coal is the main energy consumption in China,coal preparation is the source technology of clean coal utilization.Coal washing in China is mainly based on wet separation,which produces a large amount of slime water.In recent years,the content of gangue in raw coal increases gradually,which leads to the increase of cement degree of coal slime,and the high content of hydrophilic fine mineral particles makes it difficult to filter and dehydrate.Without changing the large dewatering equipment of coal preparation plant,adding filter aids to slurry is beneficial to changing the dewatering condition.It not only has the advantages of fast,convenient and efficient,but also saves money and increases benefits.In this paper,hydrophobic filter aid is used to study the filtration process of coal slime,which provides theoretical and technical support for the filtration and dewatering of coal slime.The effects of two conventional filter aids(polyacrylamide,polyaluminium chloride)and three hydrophobic modifiers(dodecyl trimethyl ammonium bromide,sodium dodecylbenzene sulfonate,benzyl trimethyl ammonium chloride)on the filtration and dewatering characteristics of fine minerals and slime were studied.The investigation of dehydration characteristics of fine minerals is mainly embodied in reagent,pH value,ion composition,particle size composition,pulp concentration and so on.The optimum dehydration agent was selected to influence the dehydration characteristics of different fine minerals and coal mixtures(different mixing proportion,different minerals,etc.).The results show that:1.Compared with the traditional filter aid,the hydrophobic modified agent has better effect of filter aid and dewatering.Among them fine minerals have the best dehydration effect under benzyltrimethylammonium chloride(MTBAC).The operating conditions are as follows:dosage of the agent is 60 g/t,stirring speed is 300 rpm,stirring time is 2 minutes,filtering time is 3 minutes,moisture content of quartz cake is 26.15%,which is 7.11%lower than that of blank test group;moisture content of kaolinite cake is 16.09%,which is lower than that of blank test group.The moisture content of montmorillonite filter cake was 21.07%,which was 4.21%lower than that of blank test group,and that of slime filter cake was 28.63%.Compared with the blank test group,it decreased by 3.85%.2.The finer the particle size of fine minerals,the greater the moisture content of filter cake,which indicates that the finer the particle size composition of fine minerals,the worse the dehydration effect of hydrophobic modifiers.3.With the increase ofpH value,the water content of fine quartz particle filter cake increases and the filtration rate decreases.Kaolinite and montmorillonite particles have the same change rule.4.With the increase of pulp concentration,the water content of filter cake decreases and the filtration rate decreases gradually.When the pulp concentration reaches 150 g/L,the pulp concentration continues to increase,and the curve of water content and filtration rate of filter cake shows a gentle trend.5.For the mixed system of different fine minerals and coal,the higher the content of fine minerals,the higher the moisture content of filter cake,and the slower the filtration speed.Considering the single factor influence of mineral types,10%of fine minerals were mixed with coal,the moisture content of filter cake of mixed slurry increased by about 1%,and the dewatering efficency decreased.6.The main action mechanism of the reagent on mineral particles is to reduce the surfece tension,increase the contact angle of mineral surface,and compress the electric double layer on the surface of the particles,so as to achieve the hydrophobic effect on the surface of the particles.Figure[63]Table[10]Reference[75]... |
