Experimental Study On Processing Wide Graded Coal Slime Of New-type Double Flotation Column

The coal slime in the coal preparation plant is usually classified at 0.5 mm, more than 0.5 mm coal power to gravity separation,less than 0.5 mm coal slime to flotation process. But due to the breakage of sieves in the slime centrifuge and so on, the centrifugal liquid and magnetic separation tailings often have much coarse clean coal. And because the classification efficiency of the classification equipment(such as the hydrocyclones) is impossible to achieve 100%, there are much coarse clean coal in the feeding slime. The conventional flotation machine and flotation column can’t recycle this portion of the slime well.On the basis of cyclonic micro-bubble flotation column(FCMC), this paper use the idea of series flotation and construct a new-type double flotation column experiment system, which consists of the first section short aeration flotation column and the second section FCMC. Through factorial experiment and orthogonal experiment, the paper explore the first section aeration rate, the feeding concentration, the collector dosage and the circulation pressure influence on the separation effect. The optimum technological parameter is determined. Comparative analysis of the separating effect under the same process conditions for flotation machine, FCMC and new-type double flotation column for wide particle grade coal, the paper explore new-type double flotation column to improve the feasibility of coarse coal slime recovery.The wide graded coal sample(0.7~0 mm) was used. The new-type double flotation column experimental results show that: under the same the first section aeration rate and feeding concentration, the total yield and ash of clean coal gradually increased with the increase of circulating pressure. When the circulating pressure is 0.14 MPa, the perfect index of flotation is higher. Under the same the first section aeration rate and circulating pressure, the total yield and ash of clean coal increased with the increase of feeding concentration, the perfect index of flotation increases first and then decreases. Under the same feeding concentration and circulating pressure, the second section clean coal yield shows a decreasing trend and the section clean coal ash gradually increased with the increase of the first section aeration rate, and the total clean coal ash also increased. When the first section aeration rate is 0.05 m3/h, the perfect index of flotation is higher. The feeding concentration, collector and the first section aeration rate have a significant influence on the total clean coal yield. The feeding concentration, the first section aeration rate and collector have a significant influence on the total clean coal ash. The feeding concentration has a obvious influence on the perfect index of flotation.Under the same process conditions, graded for 0.7 ~ 0.25 mm, FCMC recovery rate is 51.85%, and the ash is 5.91%, the recovery rate of the flotation machine is higher 3.77% than FCMC, the ash higher 0.59%; the recovery rate of the new-type double flotation column is higher 4.06% than the flotation machine, the ash lower 0.43%. New-type double flotation column low density(-1.5 kg/L)content of tail coal is lower than the flotation machine and FCMC, high density(+1.5 kg/L)ash of tail coal is higher than FCMC and the flotation machine, however, new-type double flotation column high density(+1.5 kg/L)content of clean coal is slightly higher than FCMC and the flotation machine. New-type double flotation column effectively improve the coarse clean coal recovery rate by two segment flotation.Compared to the flotation machine and FCMC, the new-type double flotation column is more advantageous to coarse clean slime recycling for the more coarse content coal slime.