Preparation method for ultra low ash coal-water slurry

Abstract

A method for preparing ultra-low ash coal-water slurry includes: (A) grinding of coal to a size below the upper size limit and then making a proper concentration slurry; (B) screening coal by using the slurry particle separation device and separating them by density into tailings, middlings and clean coal, adjusting the fraction of clean coal production according to the ash content standard of final product and then producing the clean coal slurry and tailings slurry; (C) wet grinding of the middlings in step B; (D) reprocessing the product in step C by step B. The upper size limit can be 0.2 mm, 0.01 mm or 0.001 mm, and the ash content can be below 2%, 1% or 0.5%. This method can largely enhance the production rate of clean coal, improve the coal-water slurry fuel's particle size graduation, improve the fluidity and increase the particle concentration of the coal-water slurry fuel.

1 - 10 . (canceled) 
     
     
         11 . A method of preparing ultra-low ash coal-water slurry comprising the following steps:
 A) wet or dry grinding of coal to a size below the upper size limit and then making a proper concentration slurry;   B) screening coal made in step A by using the slurry particle separation device and separating them by density into tailings, middlings and clean coal, adjusting the fraction of clean coal production according to the ash content standard of final product and then producing the clean coal slurry and tailings slurry;   C) wet grinding of middlings in step B;   D) reprocessing the product in step C by step B.   
     
     
         12 . The method of preparing ultra-low ash coal-water slurry as recited in  claim 11 , wherein said upper size limit is below 0.2 mm. 
     
     
         13 . The method of preparing ultra-low ash coal-water slurry as recited in  claim 11 , wherein said upper size limit is below 0.01 mm. 
     
     
         14 . The method of preparing ultra-low ash coal-water slurry as recited in  claim 11 , wherein said upper size limit is below 0.001 mm. 
     
     
         15 . The method of preparing ultra-low ash coal-water slurry as recited in  claim 11 , wherein said ash content of final product is no higher than 2%. 
     
     
         16 . The method of preparing ultra-low ash coal-water slurry as recited in  claim 11 , wherein said ash content of final product is no higher than 1%. 
     
     
         17 . The method of preparing ultra-low ash coal-water slurry as recited in  claim 11 , wherein said ash content of final product is no higher than 0.5%. 
     
     
         18 . The method of preparing ultra-low ash coal-water slurry as recited in  claim 11 , wherein wet grinding is performed using a slurry particle grinding apparatus, the slurry particle grinding apparatus includes a grinding zone, the grinding zone includes an annular grinding chamber, at least one set of nozzle assembly composed of jet orifices and high pressure nozzles, and discharge outlet, the jet orifices are located on the outer wall of the grinding chamber and their center lines are either tangential or oblique to the center line of the grinding chamber, high pressure nozzles are installed in the jet orifices, the discharge outlet is located on the inner wall of the grinding chamber and is communicated with the grinding chamber, cross sectional area of the grinding chamber or the discharge outlet is much larger than the total cross sectional areas of all high pressure nozzles. 
     
     
         19 . The method of preparing ultra-low ash coal-water slurry as recited in  claim 11 , wherein said slurry particle separation device is a centrifugal jig, the centrifugal jig comprises a rotating device, at least one jig unit and a product receiver, the rotating device includes a rotor and a base, the rotor is power-driven to rotate around a vertical shaft, the jig unit includes a hutch chamber, a screen residue chamber, a screen, a feeding device, a discharging device and a pulsator, the jig unit is installed on the rotor at an inclined angle along the movement of the feed, the hutch chamber is located far away from the vertical shaft to separate particles with different density in the slurry, the product receiver is used to collect the separated materials discharged from the rotating jig unit, separated materials are discharged from an outlet of the screen residue chamber. 
     
     
         20 . A method of preparing ultra-low ash coal-water slurry comprising the following steps:
 A) wet grinding of coal to a size below the upper size limit and then making a proper concentration slurry;   B) screening coal made in step A by using the slurry particle separation device and separating them by density into tailings, middlings and clean coal, adjusting the fraction of clean coal production according to the ash content standard of final product and then producing the clean coal slurry and tailings slurry;   C) reprocessing the product in step B by step A.   
     
     
         21 . The method of preparing ultra-low ash coal-water slurry as recited in  claim 20 , wherein said upper size limit is below 0.2 mm. 
     
     
         22 . The method of preparing ultra-low ash coal-water slurry as recited in  claim 20 , wherein said upper size limit is below 0.01 mm. 
     
     
         23 . The method of preparing ultra-low ash coal-water slurry as recited in  claim 20 , wherein said upper size limit is below 0.001 mm. 
     
     
         24 . The method of preparing ultra-low ash coal-water slurry as recited in  claim 20 , wherein said ash content of final product is no higher than 2%. 
     
     
         25 . The method of preparing ultra-low ash coal-water slurry as recited in  claim 20 , wherein said ash content of final product is no higher than 1%. 
     
     
         26 . The method of preparing ultra-low ash coal-water slurry as recited in  claim 20 , wherein said ash content of final product is no higher than 0.5%. 
     
     
         27 . The method of preparing ultra-low ash coal-water slurry as recited in  claim 20 , wherein wet grinding is performed using a slurry particle grinding apparatus, the slurry particle grinding apparatus includes a grinding zone, the grinding zone includes an annular grinding chamber, at least one set of nozzle assembly composed of jet orifices and high pressure nozzles, and discharge outlet, the jet orifices are located on the outer wall of the grinding chamber and their center lines are either tangential or oblique to the center line of the grinding chamber, high pressure nozzles are installed in the jet orifices, the discharge outlet is located on the inner wall of the grinding chamber and is communicated with the grinding chamber, cross sectional area of the grinding chamber or the discharge outlet is much larger than the total cross sectional areas of all high pressure nozzles. 
     
     
         28 . The method of preparing ultra-low ash coal-water slurry as recited in  claim 20 , wherein said slurry particle separation device is a centrifugal jig, the centrifugal jig comprises a rotating device, at least one jig unit and a product receiver, the rotating device includes a rotor and a base, the rotor is power-driven to rotate around a vertical shaft, the jig unit includes a hutch chamber, a screen residue chamber, a screen, a feeding device, a discharging device and a pulsator, the jig unit is installed on the rotor at an inclined angle along the movement of the feed, the hutch chamber is located far away from the vertical shaft to separate particles with different density in the slurry, the product receiver is used to collect the separated materials discharged from the rotating jig unit, separated materials are discharged from an outlet of the screen residue chamber.