Research On Recleaing Technology Of Crushing In Combination With Grinding For Dense Medium Middlings Of Tunlan Coal Preparation Plant

It’s significant for solving the problem of the shortage of coking coal resources and improving the utilization of the scarce coal resources that the effective recleaning for middlings of Coking Coal Preparation Plant.The paper research on the recleaning of the middlings after crushing and grinding through the separation process of gravity separation, grinding flotation and gravity combined with flotation on the basis of innovation of crushing combined with grinding, cascade dissociation, combination of gravity concentration and flotion, classification separation. The process is put forward by "gravity separation to throw tail, coarse grinding flotation" as the characteristics of the gravity floating combined separation process.The regular of middlings washability and crush is studied by the screening test and sin-and-float test in multi-granularity. The proper particle size is to broke to-3mm, but its washability is still very difficult.The effect of cyclone gravity separation column structure and operation parameter on the middlings separation is studied by the gravity separation test of single stage cyclone gravity separation column and two-stage cyclone gravity separation column group. Results indicate that it obtains16.44%cleaned coal with ash content of10.38%by the feed pressure at0.12MPa and the overflow tube insertion depth at100mm when taking two-stage cyclone gravity separation column group for the experiment.The results of the grinding-flotation shows that middlings of dense media separation can get good dissociation after coarse grinding in2min. It can obtain the cleaned coal yield at24.19%with ash content of10.12%by the timed release analysis, which the kerosene consumption is500g/t, and DL-2-Octanol is100g/t.It can’t obtain qualified cleaned coal under the very low dosage of the kerosene consumption at30g/t and the DL-2-Octanol consumption at20g/t. The cleaned coal yield at22.55%with ash content of9.61%can be obtained by once rough and once concentrating. However, due to the middlings floatability has been changed after the coarse grinding, the cleaned coal yield at20.16%with ash content of10.18%by the once rough flotation without flotation reagents. The analysis method of FTIR, XRD has been done to tentative explore the relative mechanism.The results of the gravity separation combined with floatation shows that the "pull head" by gravity separation can be reached, but the yield of qualified cleaned coal is too low. For coking middling of Tunlan Coal Preparation Plant, it is appropriate to throw the high ash tailing directly through cyclone separation, and then the overflow was carried out grinding and flotation, which can obtain16.44%cleaned coal with ash content of10.38%under the dosage of the kerosene consumption at30g/t and the DL-2-Octanol consumption at20g/t.The advantage of the gravity separation combined with floatation lies in energy consumption and dosage of floatation reduced while the useful constituent recycling effectively. But the ash content of the tail is subnormal, the structure of the gravity separation equipments should be further optimizing to enhance the separation indices in order to carry out discarding tailing thoroughly.