Study On The Modification And Adhesion Behavior Of Oily-bubble In Low Rank Coal Flotation

Low rank coal occupies more than 55% of proven coal reserves in China.The combustion of coal has result in heavy environment pollution.With the adjustment of economic structure and improvement of environmental protection requirements,it is an important task to increase the washing ratio of low rank coal and develop efficient separation and quality improvement technology.But the low rank coal flotation technology failed to achieve industrial application because of its high hydrophilicity which could cause high consumption of collectors.Base on existing research results,three kinds of polar regents were used to modify diesel oil and lignite modified oilybubble flotation was conducted.The collision and adhesion process were observed to explain the mineralization difference before and after oily-bubble modification.Various methods were employed to evaluate the performance of modified oily-bubble.And the interaction mechanism of modification regent was analyzed.This paper could provide some references for low rank coal flotation.2-Ethylhexanol,2-octanone and methyl phenylacetate were used as modification regents.In laboratory flotation test,the combustible matter recovery of 20 wt% of 2-ethylhexanol and 2-octanone modified oily-bubble is respectively 41.98% and 41.95%,which increased more than 60% compared with diesel oily-bubble flotation.However,the promotion of methyl phenylacetate is not obvious.The induction time test result showed that the lowest induction time of 2-Ethylhexanol and 2-octanone modified oilybubble is 40 ms,which greatly reduced the time for bubble spread and adhesion.The collision and adhesion process under static conditions between single particle and bubble/oily-bubble was tracked and measured.It was found that the average slide speed of particle on 2-ethylhexanol,2-octanone and methyl phenylacetate modified oily-bubble surface is respectively 5.67、5.53、5.51 mm/s at 12 wt%,which are higher than that of bubble and diesel oily-bubble.The latter is respectively 3.66 and 4.69 mm/s.The average slide angle of particle on 2-ethylhexanol,2-octanone and methyl phenylacetate modified oily-bubble surface is respectively 167°,170.5° and 169°,higher than 148° of particle on bubble surface.The result show that modification regent could increase the adhesion capacity of oily-bubble to course particle.The FT-IR fitting data revealed that polar regent could reduce infrared absorption intensity of O-H and C-O on lignite surface.The O-H absorption peak area of 2-ethylhexanol and 2-octanone modified oily-bubble flotation concentrate is respectively reduced 33% and 16%.Combined with group electronegativity calculation results and the interaction pattern,it can be concluded that modified oily-bubble is better in adhesion velocity and adhesion force.And hydrogen bonding plays a key role in improving the capability of oily-bubble.