Study On The Emulsification Of Diesel Oil And Its Effects On Floatation Efficiency

With the rapid development of China's national economy,The demand for energy is on the increase day by day.Meanwhile Coal is the main energy source in China,The effective growth of its quantity and quality,it is the basic guarantee for sustained,healthy and rapid development of the national economy.Faced with the enormous pressure of energy conservation and environmental protection,the efficient and clean utilization of coal resources is an inevitable requirement for the development of the coal industry.With the continuous development and progress of coal mining technology,the proportion of slime in raw coal is increasing.Because of this change for separating raw coal,flotation is the most important and effective method to treat coal slime and its importance is becoming more and more prominent In the coal separation process.Flotation reagent for coal is the basic factor of coal flotation,its research,development and innovation has become the forefront and hot spot of coal preparation industry technology hot spot.The collector for coal flotation as an important component of the cost,occupy most of the economic cost of flotation.At present,the industrial application of collector is mainly kerosene,diesel and other non-polar hydrocarbon oil,because the oil does not dissolve in water,and has poor dispersity in water,often exists in the form of large droplets in the pulp,causing the collector consumption to increase,selectivity of coal particles to decrease,and the collecting effect is poor.To solve these problems in this paper,using diesel and water as raw material,without adding emulsifier,emulsified diesel oil and water using colloid mill.Research on time parameters and oil ratio parameters of the emulsified process used Experimental method.Do the floatation experiments with the slime coal which were from one coal separating plant in Xing country Shanxi Province using the emulsified diesel oil and diesel oil as collector.The main contents of this paper are as follows:(1)The particle size analysis of coal sample shows that the content of each particle fraction is disproportion,the content of big particle slime is too many,and the content of +0.125mm particle size is as high as 64.82%,while the content of +0.25mm particle size is as high as 40.07%.Except the ash of less than 0.045mm particle size slime is slightly higher.the ash of other particles is similar,which indicates that there is the phenomenon of Gangue argillization.(2)The density analysis of coal sample shows that the content of intermediate density of coal sample is many,especially the content of 1.40g/cm3-1.60g/cm3 density class is up to 32.36%.The more the content of intermediate density is,the more difficult it is to separate.because this coal sample used as coking coal and the ash of cleaned coal should be controlled below 10.50%.If coal sample separated according to density,the separation density should be controlled between 1.50cm3-1.60cm3,and the yield of clean coal should be between 55.92%-71.95.(3)In order to further understand the performance of coal slime's floatation,exploratory experiments,four factors and three levels orthogonal test and floatation step release test were carried out,and finally confirmed the optimal conditions for flotation as follows:the dosage of n-dodecane is 800g/t;dosage of DL-2-Octanol is 120g/t;floatation pulp concentration is set to 80g/l;aeration rate is set to 0.20m3/(m2·min).Through the fractional release slime floatation experiment,the Primary flotation yield of clean coal is up to 76.90%,but the ash content is higher than 14.34%,and the entrainment of high ash is obvious.secondary flotation is needed in practice.(4)Through the preparation experiment of emulsified diesel oil,it is determined that the emulsification efficiency is 0.79 when the emulsified diesel is produced by colloid mill.When emulsified diesel oil is prepared at different oil-water ratios,the emulsification effect is best when oil-water ratio is between 1:4 and 1:5.The diesel emulsified oil prepared under the best conditions was observed under the microscope.The size distribution of the diesel oil was calculated.The results showed that the average size of the droplets was 3.2microns,and the distribution of the droplets was concentrated In a very small length range.(5)The Contrast flotation experiments were did using the emulsified diesel oil and diesel oil.The results of experiments show that the emulsified diesel oil as collector are better than the diesel collector in the clean coal ash,the clean coal yield,the combustible recovery and the floatation complete index.when the floatation complete index were 57.66%,The consumption of the emulsified diesel oil is 39.13%less than the consumption of diesel oil.(6)In the flotation speed experiment,emulsified diesel oil as collector,0.25min scraped clean coal yield was 27.16%,the yield of clean coal is 5.01%higher than diesel oil,good dispersion performance promote the integration of coal particles and oil droplets,accelerate the mineralization process of flotation bubble,significantly improve the flotation speed.(7)In contrast experiments of flotation at different particle sizes,emulsified diesel oil has obvious advantages for the flotation performance of particles smaller than 0.045mm particle size,and its floatation complete index is 4.96%higher than that of diesel oil as collector.Because to the same weight of the coal sample,the smaller the particle size,the greater the surface area,and the greater the consumption of the collector.Compared with diesel oil,emulsified diesel oil droplets have smaller particle size and larger surface area,thus reducing the consumption.