Classifying – separating – and assorting solids – Electrostatic
Reexamination Certificate
2000-01-19
2001-10-23
Nguyen, Tuan N. (Department: 3653)
Classifying, separating, and assorting solids
Electrostatic
C209S128000
Reexamination Certificate
active
06307170
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a method of separating particles dispersed in a liquid and to a device therefor.
Conventional techniques for separating particles dispersed in a liquid include sedimentation, agglomeration with an agglomerating agent and filtration. Sedimentation requires a long time for the separation. The use of an agglomerating agent has a problem because it remains in the liquid phase. Filtration causes a problem of clogging of the filter, especially when the particles have a diameter of 30 &mgr;m or less.
For measuring particle size distribution of a suspended liquid Field Flow Fractionation (FFF) method and Hydrodynamic Chromatography (HDC) are known. These methods, however, cannot separate particles from the suspended liquid.
With a view toward theoretically explaining aggregation and dispersion phenomena in a colloidal dispersion system, DLVO theory has been proposed. Further studies made to develop and modify the DLVO theory results in a method of measuring forces acted between solid particles of mica. No methods are known, however, which can measure a force required for detaching negatively or positively charged particles from an outer surface of a rotor.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a method which can easily separate fine liquid or solid particles dispersed in a liquid.
Another object of the present invention is to provide a method of the above-mentioned type which can selectively separate particles with a desired particle size range.
It is a further object of the present invention to provide a method which can measure a force required for detaching negatively or positively charged particles from an outer surface of a rotor.
It is yet a further object of the present invention to provide a simple device useful for carrying out the above methods.
In accomplishing the foregoing object, there is provided in accordance with one aspect of the present invention a method of separating negatively or positively charged particles dispersed in a liquid, comprising the steps of:
immersing a rotor having an outer surface charged in a polarity opposite to said particles in said liquid; and
rotating said rotor to capture said particles on said outer surface.
In another aspect, the present invention provides a method of separating negatively or positively charged particles dispersed in a liquid into a first class of particles having a relatively large particle size and a second class of particles having a relatively small particle size, comprising the steps of:
immersing a cylindrical rotor with a circular cross-section in said liquid, said rotor having an outer surface charged in a polarity opposite to said particles; and
rotating said rotor about its axis at a rotational speed sufficient to capture said second class of particles on said outer surface but insufficient to capture said first class of particles on said outer surface.
The present invention further provides a method of measuring a force required for detaching negatively or positively charged particles from an outer surface of a rotor with a circular cross-section, comprising the steps of:
immersing said rotor in a liquid in which said particles are dispersed, said outer surface of said rotor being charged in a polarity opposite to said particles;
rotating said rotor about its axis at a constant rotational speed sufficient to capture some of said particles on said outer surface; and
measuring the diameter of that particle which has the largest diameter among the captured particles on said outer surface.
In a further aspect, the present invention provides a device for capturing negatively or positively charged particles dispersed in a liquid, comprising:
a rotor having an outer surface charged in a polarity opposite to said particles and arranged so that said outer surface can be in contact with said liquid; and
drive means for rotating said rotor, whereby said particles are captured on said outer surface.
REFERENCES:
patent: 4251353 (1981-02-01), Knoll
patent: 4334987 (1982-06-01), Mamadzhanov et al.
patent: 4799452 (1989-01-01), Day
patent: 4923581 (1990-05-01), Day
patent: 787088 (1980-12-01), None
patent: 1331567 (1987-08-01), None
Oki Tatsuya
Yotsumoto Hiroki
Lorusso & Loud
Nguyen Tuan N.
Secretary of Agency of Industrial Science and Technology
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