Cleaning and liquid contact with solids – Apparatus – Sequential work treating receptacles or stations with means...
Reexamination Certificate
1999-04-26
2001-08-14
Stinson, Frankie L. (Department: 1746)
Cleaning and liquid contact with solids
Apparatus
Sequential work treating receptacles or stations with means...
C134S131000, C134S132000, C134S201000
Reexamination Certificate
active
06273106
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Filed of the Invention
The present invention relates to a particulate matter washing apparatus or method for washing contaminated particulate matter scraped up from filtering media in a filtering pond or from a bottom of a waste water pond or a sedimentation basin, etc., or surface-covering sand to remove muck on or materials covering the surface of the grains of the particulate matter.
2. Description of the Prior Art
Filtering sand used in a water purifying plant is collected from a river bottom or a river-mouth, but a quantity of the resource is limited, so that sand once used is again used after cleaning or other similar processing. In association with rapid contamination of resource water or under influence caused by contaminants flowing into a filtering pond, such phenomena have been observed as that a grain diameter of the filtering material has become larger due to deposition of sludge or that sludge is separated from the filtering media. When a grain diameter of filtering media becomes larger as described above, a space between the filtering media is reduced and the filtering efficiency becomes lower. So it is required to periodically take out the filtering media from the filtering pond and remove muck from a surface of the filtering media by means of washing.
Conventionally, in the processing for washing filtering media, generally there has been used a washing apparatus having agitation vanes to mix contaminated sand and cleaning water and agitate the mixture, but when a large quantity of contaminated sand is forcefully agitated, the sand grains are pulverized due to collision with the agitation vanes or friction between the filtering media themselves, and resultantly a portion which can not be recycled increases, and further if a quantity of cleaning water is small, the separated contaminants are again deposited on the sand grains, which makes it difficult for us to expect high efficiency in the processing for cleaning.
Also as the so-called washing apparatus for sand, there has been proposed an apparatus having a sand scrape-up section at a central position of the basic body for agitating and washing sand by making use of rotation of a screw conveyor provided in the sand scrape-up section. This sand washing apparatus is an apparatus used mainly for removing salt deposited on a surface of sea sand, and has the construction in which the screw conveyor has sand scrape-up vanes in its lower section and also agitation vanes on its upper section and blades for distribution are provided in the upper section of the sand scrape-up section.
In this type of sand washing apparatus as described above, sand put in a cleaning tank is raised due to effect by sand scrape-up vanes up to the agitation vane section, where the sand is mixed with cleaning water poured thereinto, the sand in the cleaning water is agitated, diluted, washed, and further raised upward by making use of rotation of agitation vanes, and then the sand is homogenized and forcefully moved from the sand scrape-up section to the cleaning tank. Because of this construction, it is required to inject sand into the cleaning tank up to at least a height of the blades for distribution, and further the cleaning water is supplied at a section where the agitation vanes rotate and salty water after cleaning is overflown from a water discharge pipe provided in the upper section of the cleaning tank, so that the cleaning tank is always required to be filled with the cleaning water.
As described above, generally the conventional type of sand washing apparatus has the configuration in which sea sand filling a tank is floated in and agitated with cleaning water to make salt deposited on a surface of sand grain dissolved in the cleaning water to acquire cleaned sand.
Even if filtering media is washed by using the conventional type of sand washing apparatus as described above, however, contaminants deposited on a gain surface are, different from salt, not dissolved into cleaning water, so that it has been impossible to expect a high cleaning effect. Also, when a supply rate of cleaning water is lowered to suppress floating of sand to be cleaned, as a large quantity of contaminated sand is forcefully agitated by the agitation vanes, which sometimes causes breakage pulverization of sand gains. Also as the sand scrape-up vanes and agitation vanes continue to rotate in the sand, so that friction between the agitation vanes and sand is disadvantageously large.
It is an object of the present invention to provide a sand washing apparatus which can effectively remove contaminants despited on and covering a surface of sand gain without pulverizing the injected sand and also in which wearing is generated little in the agitation member.
SUMMERY OF THE INVENTION
To solve the problems as described above, the present invention provides a method of washing contaminated particulate matter comprising:
providing a cleaning tank, for storing the contaminated particulate matter and cleaning water, in which the contaminated particulate matter and the cleaning water are contained in their respective predetermined amounts and in which a screw conveyor is disposed for rotation around a substantially vertical axis so that the lower part of the screw conveyor is positioned under the surface of the cleaning water contained in the cleaning tank and the upper part of the screw conveyor is positioned above the surface of the cleaning water in the cleaning tank;
contacting, under the surface of the water, the grains of the particulate matter with each other with sludge, which comes from the contaminated particulate matter and is present in the water, being interposed therebetween to remove at least a part of contamination substances from the surface of the grains of the particulate matter and to wash off the substances into the water, while raising the particulate matter and the water by means of the rotation of the screw conveyor under the surface of the water;
fluidizing, above the surface of the water, the particulate matter on the surface of the screw conveyor and thereby contacting the grains of the particulate matter with each other with a slight amount of the water including the sludge being interposed therebetween to remove at least a part of the remaining contamination substances from the surface of the grains of the particulate matter; and
allowing the particulate matter, which has been raised, to fall down to the lower part of the screw conveyor through a way outside the screw conveyor;
whereby the contaminated particulate matter is cleaned off by way of repeating the raising and falling.
When the particulate mater is allowed to fall down, it is preferable to drop the particulate matter onto the surface of the water in the cleaning tank in order to avoid collision of the grains of the particulate matter with each other so that the grains of the particulate matter can be prevented from breaking or smashing into pieces.
It is preferable that the cleaning water is not replaced until the washing of the particulate mater is completed, but a part of the water may be replaced with unused water during the washing of the particulate matter. The presence of the sludge in the cleaning water provides better results in washing the particulate matter.
The surface of the water in the cleaning tank is preferably maintained at a height ranging from ½ to ⅔ of the height of the screw conveyor. The weight ratio of the particulate matter to the water in the cleaning tank may be set to be between 1.0:1 and 4.5:1 if it is desired. The screw conveyor is preferably rotated at a speed such that the water can be raised to the top of the screw conveyor.
Examples of the particulate matter as used herein include sand, particles of various kinds of minerals including zeolite, ion-exchange resins, scraps or debris of plastics or metals, such as those for recycling use, fine copper particles or powder obtained from etching waste liquid, and any other particulate substances.
The present invention also provides a particulate matter washing a
Flynn ,Thiel, Boutell & Tanis, P.C.
Nihon Genryo Co., Ltd.
Stinson Frankie L.
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