Liquid purification or separation – Filter – Material
Reexamination Certificate
1997-12-10
2001-05-01
Savage, Matthew O. (Department: 1723)
Liquid purification or separation
Filter
Material
C210S504000, C210S505000, C162S142000, C162S161000, C162S164200, C162S181500
Reexamination Certificate
active
06224768
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a paper for filtering laden liquids, with a high adsorption and absorption capacity, exhibiting a high porosity, based on natural and/or synthetic cellulose fibres additionally comprising pulverulent organic matter. It may also comprise inorganic pulverulent matter and bactericidal and/or viricidal agents.
It finds its application in the crude oil processing industries, the industries which employ lubricating oils or machining fluids, the papermaking industries, the agri-foodstuffs industries and, in general, all industries which produce suspensions or emulsions that are rich in fats or waxes. It also finds its application in the filtration of the aqueous effluents produced by households and communities.
STATE OF THE PRIOR ART
Papers based on synthetic or natural fibres, employed in numerous applications for filtering liquids, are well known. In the case of industrial applications they exhibit some disadvantages especially because of their low porosities which entail mediocre rates of filtration, expressed as volume of liquid treated per unit time and per unit area.
The papers have insignificant adsorption capacities and reactivity; they do not make it possible to bind products such as phenols even in very small quantities in the liquids which are treated.
The known papers are ineffective for filtering very stable suspensions whose stability is the result of the presence of surface-active agents, and have no deodorizing power.
In addition, they are unsuitable for the treatment of liquids at a temperature higher than 90° C.
It is also known to employ papers filled with talc or bentonite, which have a hydraulic capacity lower than that of unfilled paper.
DESCRIPTION OF THE INVENTION
The aim of the invention is precisely to remedy these disadvantages. To this end it provides a filter paper for liquids, with a high adsorption and absorption capacity and with high porosity, based on cellulose fibres additionally comprising at least one pulverulent organic matter in which at least 95% of the particles have a particle size of between 1 and 150 microns, in a proportion of between 5 and 75% of the weight of the paper including the said organic matter.
According to another characteristic of the invention the organic matter includes a micronized active carbon of particle size between 5 and 50 microns, in a proportion preferably of between 5 and 70% of the weight of the paper including the said organic matter.
According to another characteristic of the invention the active carbon consists of at least one micronized coke chosen from coal cokes, petroleum cokes and lignite cokes.
According to another characteristic of the invention the organic matter includes a micronized roasted wood of particle size between 50 and 150 microns.
According to another characteristic of the invention the organic matter includes a conifer powder.
According to another characteristic the paper of the invention additionally comprises at least one inorganic material in a proportion of 0.2 to 70% of the weight of the paper including the said organic matter and the said inorganic material.
According to another characteristic of the invention the inorganic material is a product derived from silica, in powder form.
According to another characteristic of the invention the inorganic material is a product derived from alumina, in powder form.
According to another characteristic of the invention the inorganic material is a pulverulent catalyst of particle size between 2 and 100 microns.
According to another characteristic the paper of the invention additionally comprises a pH-modifying agent.
According to another characteristic the paper of the invention additionally comprises a bactericidal agent.
According to another characteristic the paper of the invention additionally comprises a viricidal agent.
According to another characteristic the paper of the invention has undergone a treatment to make it oleophilic.
According to another characteristic the paper of the invention has undergone a treatment to make it water-repellent.
Other characteristics and advantages of the invention will be seen better on reading the detailed description and the examples which are to follow.
DETAILED DESCRIPTION OF THE INVENTION
The subject-matter of the invention is a filled filter paper produced from natural and/or artificial cellulose fibres to which organic matter in the form of powders is added to improve its hydraulic capacity without appreciably impairing the other characteristics.
This result is illustrated by the following table:
Test references
V2
V3
V1
WP = 80%
WP = 60%
Units
WP = 100%
OF = 20%
OF = 40%
Weight/unit area
g/m
2
267
276
277
Thickness
&mgr;m
373
481
528
Hydraulic
m
3
/m
2
/h
0.9
5.6
7
capacity
In which:
V1, V2, V3 are three variants of paper composition.
WP means recovered wastepaper forming the cellulose fibres.
OF means organic filler; in this example spruce powder of particle size smaller than 150 microns.
The hydraulic capacity is the water flow rate in cubic metres per hour and per square metre of paper area, measured at 25° C.
To observe the effects of various fillers in powder form, five tests were performed, the results of which are as follows:
Test references
E3
E4
E5
E1
E2
WP = 55%
WP = 55%
WP = 68.5%
WP = 100%
WP = 80%
OF = 20%
OF = 20%
OF = 20%
Units
OF = 0%
OF = 20%
Talc = 25%
Bentonite = 25%
Coke = 11.5%
Hydraulic capacity
m
3
/m
2
/h
0.9
4.5
3.7
2.1
7.5
In which:
E1, E2, E3, E4 and E5 are the references of the five tests.
WP means recovered wastepaper forming the cellulose fibres.
OF means organic filler; in this example spruce powder of particle size smaller than 150 microns.
The hydraulic capacity is the water flow rate in cubic metres per hour and per square metre of paper area, measured at 25° C.
On comparing the results of tests E1 and E2 it is found that the fact of filling the paper with an organic powder has the effect of increasing the hydraulic capacity of the paper.
The addition of talc or of bentonite, represented by tests E3 and E4, produces the opposite effect, that is to say that the hydraulic capacity decreases.
When the paper of test E2 is filled with coal coke which has a particle size smaller than 150 microns the hydraulic capacity changes from 4.5 to 7.5 m
3
/m
2
/hour. These results show that the paper of the invention is a filter material whose characteristics can be adapted to the liquid to be filtered by modifying its composition in quality and in quantity.
The paper of the invention can be employed as filter medium with known devices making use of known processes. As example there may be mentioned belt filters with paper unwinding, in which the solid matter in suspension in the liquid to be filtered is retained on the paper to form a cake, some products are adsorbed in the powder which fills the paper, and the filtrate consisting of the coalesced liquid components is collected.
The paper of the invention can also be used by means of known filters of the vacuum rotary type.
According to another characteristic of the invention the organic matter filler of the filter paper includes at least one active carbon of particle size between 5 and 50 microns.
By way of example there may be mentioned active carbons obtained in ovens from vegetable matter such as coconuts, olive stones and cork. These active carbons are micronized and preferably represent 5 to 70% of the weight of the cellulose fibres.
The small diameter of the pores of these materials, of the order of 25 Å, increases the adsorbency of the paper.
Paper filled with active carbon powder is particularly suited to the filtration of suspensions and lightly laden water. It has the advantage of retaining aromatic hydrocarbons, especially benzene, as well as the organic products of spent lyes, pesticides and detergent organochlorine products.
When a very high hydraulic capacity is required, then the organic matter employed for filling the paper fibres is mi
Bossand Bernard
Dussaud Joseph
Girard Pierre
Navarre Francois-Pierre
Elf Antar France
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Savage Matthew O.
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