TH73665A - Process for washing solid particles - Google Patents

Abstract

DC60 (12/11/56) In the washing process of the invention, the solid particles in the high concentration zone, which are formed in the washing tank by the gravitational deposition of the solid particles, are continuously washed in a counter-current manner against the upflow of the washing fluid fed from the bottom of the washing tank. In this process, the impurities in the solid particles are sufficiently removed by the simple apparatus. Since the washing fluid used can be recycled as a dispersion medium for the solid particles and as a washing fluid, the amount of washing fluid used to be discharged as a waste from the system is reduced. In the washing process of the invention, the solid particles in the high concentration zone, which are formed in the washing tank by the gravitational deposition of the solid particles, are continuously washed in a counter-current manner against the upflow of the washing fluid fed from the bottom of the washing tank. In this process, the impurities in the solid particles are sufficiently removed by the simple apparatus. Since the washing fluid used can be recycled as a dispersion medium for the solid particles and as a washing fluid, the amount of washing fluid used to be discharged as a waste from the system is reduced.

Claims (8)

1. The process for continuous washing of solid particles consists of: (1) feeding solid particles into the washing tanks from the top of the tanks and allowing the solid particles to settle by gravity, and creating a high concentration zone of solid particles in the washing tanks, where the concentration of solid particles in the high concentration zone is 15-50% by volume, where the high concentration zone is stirred by a stirring machine, which has disc-shaped stirring blades, where the speed of the stirring machine is controlled to be in the range of 0.48 to 5 m/s, in terms of the high concentration by the stirring machine, which consists of a stirring shaft extending in the vertical direction and a number of stirring blades fitted to the stirring shaft in the vertical direction; (2) feeding the washing liquid into the washing tanks from the bottom of the lower tanks so that the fed washing liquid flows upward; (3) bringing the solid particles into contact with the washing liquid in a counter-current to the upward flow to wash the solid particles; (4) discharging the washed solid particles as a slurry together with the remaining solid particles. Washing liquid; and (5) separation of the washed solid particles from the slurry, where the height of the high concentration zone, from the bottom of the washing tank, is 0.5 to 0.95 times the height of the washing liquid outlet from the bottom of the washing tank, after the washing liquid has been used to wash the solid particles. 2. The process under claim 1, in which solid particles are fed into a washing tank as a slurry together with a dispersing medium. 3. The process under claim 2, in which the remaining mother liqueur after separation of the washed solid particles from the discharged slurry is recycled as a dispersing medium. 4. Any of the processes under claims 1 through 3, in which the remaining mother liqueur, after separating the washed solid particles from the discharged slurry, is recycled into a washing liquid. 5. Any of the processes under claims 1 through 4, where the concentration of solid particles in the high concentration zone is 15 to 50% by volume. 6. Any of the processes under claims 1 through 5, which involve the use of a high-intensity machine to transport the substance. 7. The process pursuant to claim paragraph 6, which is performed manually to create a circular flow in a high-intensity area by a mechanical device consisting of a shaft and a number of blades fitted precisely to the shaft in its vertical direction. 8. Any of the processes under claims 1 through 7, in which the solid particles are aromatic crystalline polycarboxylic acid.