MXPA00000472A - Floor absorbent granular product - Google Patents

Abstract

Granular absorbent products with low amounts of paper fiber are made from recycled paper and include less than about 10%of paper fibers having a length sufficient to be retained on a 100 mesh screen. The granular absorbents are useful for absorbing liquids spilled on the floor, and are crushable when walked on to provide greater resistance to slipping, and yet have a high resistance to attrition. Process for making granular absorbent material from wastepaper by screening (6) the wastepaper into papermaking fibers and a reject stream, dewatering (40) the reject stream to form a filter cake, breaking up (44) the filter cake to form granular material and sending the granular material which has been dried by dryer (46) to a pin mixer (48).

Description

ABSORBENT GLOBAL PRODUCT FOR FLOOR FIELD OF THE INVENTION The present invention relates to floor absorbent materials for absorbing water, oil and other liquids from a floor.

BACKGROUND OF THE INVENTION When paper such as bead paper or magazine paper is first recycled by decomposing the paper into a slurry of pulp containing its individual components, the large cellulose fibers are recovered so that they are useful for making fabric or other products of paper. The slurry also contains a significant amount of other materials including mainly kaolin clay and short cellulose fibers which are not useful for making fabrics. In an effort to make maximum use of materials in pulp slurry, several products They have been developed.

REF.:32159 One of the products that has been developed is a granular absorbent product which is made by a process that is known as the KAOFIN process and is described in the North American patent application Series No. 08 / 852,419, filed on 8 May 1997, which is incorporated herein as a reference for the description of the process for making absorbent granules. The granular product of this process is described in the co-pending applications, Series No. 08 / 857,302 filed on May 16, 1997, and Series No. 08 / 929,601 filed on September 19, 1997, which is incorporated herein by reference for a description of the granular absorbent product made by the KAOFIN process. The desirable characteristics for products. Granular absorbers include a high rate of liquid absorption, a high volumetric density, and a high resistance to friction For example, US Patent No. 4,343,751 (the? 751 patent) discloses a process for making absorbent pellets from clay that can be used as a floor absorber The '751 patent describes the use of paper sediment in quantities between ten percent and fifty percent of the total mass of agglomerated solids, however, the absorbency is less than ideal as seen in the examples which include pellets having 50% paper waste and 50% clay fibers, a volumetric density of 38 lbs / ft and only 78% absorbency (see Chapter 2, sample 008). Another example is described in U.S. Patent No. 5,019,564 (the x564 patent) which is directed to agricultural granules without clay.The granules are formed by the agglomeration agitator of an acid paste. It is a fiber of plant and looks like a clay granule in all aspects except for its chemical inactivity. Clay products, such as those described in the '751 patent, have the disadvantage of low absorbency, when mixed with paper sediment, and relatively high friction rates when the fiber content is lower, as described in the patent ? 564. When used as a floor absorbent, it is desirable that the granules retain their integrity after absorbing water or oil from the floor. Another problem encountered with granular floor absorbers is that the granules are generally spherical and tend to coil across the floor. When a worker steps on the granules, there is a danger that the granules cause the worker to slip and fall when the granules roll under their shoes.

DESCRIPTION OF THE INVENTION Therefore, it is an object of the present invention to provide an improved granular absorbent product made from recirculated waste paper and having a high absorbency, a high friction resistance, and a relatively high bulk density. It is a further object of the present invention to provide a granular absorbent product having a sufficiently high bulk density to provide an effective commercial absorbent that can be used to absorb oil and water and other liquids. It is another object of this invention to provide a granular absorbent that resists the bearing when it is stepped on by a worker after it has expanded on the floor to absorb the liquid. Another object of the present invention is to provide a process for manufacturing an improved granular absorbent product. These objects are made by the present invention which comprises a granular absorbent product that contains little fiber, made from recycled paper and containing kaolin clay and paper fiber. The paper fiber contains less than about 10% by weight of fibers having a greater length than the width of the openings in a 100 mesh screen (0.149 inches) and an absorbency for water of at least 0.90 ml / g and resistance to friction of at least 99%. An important feature of this invention is that the fibers suitable for papermaking, generally referred to as long fibers, are efficiently removed from the slurry pulp, so that the secondary stream contains a larger portion of fibers that are too much. short for making paper, generally referred to as short fibers. The procedure used to determine the length of the fiber is described in TAPPI method T233 (1995). Using this procedure, it is determined that less than 10% by weight of the fibers in the secondary stream were retained in the 100 mesh screen (North American standard), which had 0.149 mm openings. The preferred granular floor absorbent of the present invention is compressible when stepped by a worker and has a coefficient of friction greater than 0.50, but has a frictional resistance of at least 99%.

BRIEF DESCRIPTION OF THE DRAWINGS A preferred embodiment of this invention is contemplated in the following description and is illustrated in the accompanying drawings, in which: Figure 1 is a schematic diagram of a preferred embodiment of the process of this invention for manufacturing a improved absorbent granular product.

DETAILED DESCRIPTION The process of this invention uses waste paper that is collected from offices or other sources containing mainly recyclable grades of paper, including magazines (with clay-based coatings) and writing classes (with laser printing, photocopying printing and other 'inks'). Referring to Figure 1, waste paper, such as waste paper from offices and magazines, is supplied to a hydropulpator 2 together with water, caustic agents, such as sodium hydroxide, and dispersants to separate the fiber from others. waste paper components and to form a waxy paste. Plastics, waste and other foreign objects are removed by conventional means. The pulp slurry of the pulp hydroformer, which contains more than 95% water, passes through a pipe 4 to a scrubber or cleaner 6 where several conventional washing steps are carried out. In the cleaner 6, the slurry flows over wire sieves where the fibers are long enough to make paper, are retained in the screens and the secondary stream containing short fibers and other solids passes through the screen. The stream of fibers useful for making paper is led from the waste through a pipe 8. The screens have slotted openings of about 100 to 300 microns wide. Fibers that are long enough to be suitable for papermaking are preferably collected on the surface of the screens, while small particles, such as kaolin clay, short cellulose fibers, fine cellulose particles and other suspended solids, pass through. through the sieves in a secondary stream. Some of the fibers suitable for making paper are also passed in the final form through the screens in the secondary stream. The fibers that are retained on the screen are subjected to further cleaning, de-inking and processing, indicated at 10, before being supplied through line 12 to a papermaking machine 14. The secondary stream of the screen cleaner of wire 6 flows through pipe 16 to a dissolved air flotation clarifier 18 in the form of a slurry that typically contains less than 1.5% solids, including fine particles of cellulose, short cellulose fibers and inorganic materials. The percentages set forth in this specification are percentages by weight unless otherwise specified. Typically about 50% solids by weight are inorganic materials such as kaolin clay, calcium carbonate and titanium dioxide. The remaining solids are organic materials, typically cellulose fibers that could pass through a 100 mesh screen, fine cellulose particles, some sugars, tannins and lignins. Prior to the introduction of the slurry-mixed paste to the flotation clarifier 18, a flocculating polymer and air are added as indicated in Figure 1. Suitable dissolved air flotation clarifiers are commercially available. A flocculating polymer, such as Dre floc® 441 or 442 from Ashland Chemical Co., or Calgon® TRP 945, and air are added to the secondary stream in line 16 before they enter the clarifier. The watery paste fills the clarifier 18, and flocculated suspended solids float in the air bubbles to the surface of the clarifier. At this point, the solids mat, which has a consistency of 3-7%, slides or is swept from the surface and removed from the clarifier through a pipe 20. Some portion of clarified water from the clarifier 18 is conducted back to pulp hydroformer 2 through line 22 to be reused. The clarifier stream 18 flows through the pipe 20, and a second flocculating polymer, such as Drewfloc® 453 from Ashland Chemical Co., is added to the slurry to promote drainage in the drain press 40. The drain press may be a belt press or a series of presses. , such as a band press followed by a pinch press or screw press to achieve the desired solids content in the filter cake produced in the dewatering press or presses. The band press 40 can be any suitable commercially available unit, such as a Belt Filter Press from Komline Sanderson. Depending on the volume of material that is processed, several band presses can be arranged in parallel to provide the desired capacity. The clean water from web process 40 is preferably conducted to the pulp hydroformer through line 42. If a series of presses is used so that the web press is followed by a clamp press or screw press, the dewatered cake can have a solids content such as 55%. As shown in Figure 1, the effluent stream includes a stream of clean water for the process 23 from the papermaking machine 14, an overflow stream 24 which could have been previously discharged to a culvert, and a stream of clean water 25. The clean water from the process is returned to the cleaner 6. The overflow current 24 is administered to a fiber recovery process 26 where the current passes through sieves separating the long fibers from a similar manner to the cleaner 6. The long fibers with water are supplied through the pipe 28 from the fiber recovery unit 26 to the cleaner 6. A slurry essentially free of papermaking fibers flows through the filter. the pipe 30 to the pipe 16 upstream of the addition of the flocculating polymer and air. The clean water stream 25 from the papermaking machine is supplied to another flotation clarifier 27 where the flocculated suspended solids are removed in the same manner as in the clarifier 18. The float product of the clarifier 27 flows through the pipeline 34 to mix with the float of the clarifier 18 to form a single concentrated stream in the pipe 20. The flocculating polymer is added to the float in the pipe 20 upstream of the band press 40. The filter cake is discharged from the press. band 40 in the form of a sheet of wet particles which easily fall away. At the outlet of the web press, the filter cake had 35-45% solids, preferably 36-40% solids. If a pinch press or screw press is used for further dewatering of the cake from the web press, the solids content of the cake can be increased up to 55%. The filter cake is transported by means of a screw conveyor 44 from the web press 40 or the secondary press, if used. The filter cake breaks when it passes through the screw conveyor 44. From the screw conveyor 44, the granulated product but still wet material (35-55% solids) is directed in a conveyor dryer 46. conveyor dryer 46 preferably includes a housing through which the granular material moves while being supported in a moving web. The band is porous and the hot air is circulated through the band to dry the granules. A preferred minimum solids content is 90% by weight, and preferably greater than 95%.

The dried granules are transported from the transport dryer 46 to a bolt mixer 48, such as the Ferro-Tech Turbulator. The bolt mixer 48 has a cylindrical frame and a rotary shaft mounted on the central axis of the frame. The frame is stationary and supported on a frame such that the central axis of the frame is substantially horizontal. The shaft has radial bolts that are spread out from the inside wall of the frame. The dried granules of the conveyor dryer 46 are deposited in the frame at one end of the frame. The filling speed of the frame should be adjusted so that the cake material substantially fills the volume of the frame. A surfactant such as Surfonic L 24690, from Huntsman Chemical, or any other suitable wetting agent is added to the granules at a ratio of 5-10 lbs / dry granular tar. The granules are advanced through the bolt mixer by the rotation bolts. It is believed that the granules develop light cracks that allow it to be compressed under the foot, and still retain a high resistance to friction during shipping. After the bolt mixer 48, the still hot granules of the dryer 46 pass through a vibration screen sorter 50 to remove granules that are too long or too small to facilitate handling. It is advantageous to pass granules through a dust removal device 52 to remove any remaining dust particles and loose fibers. For dust removal, it is preferred to use a fluidized bed de-duster, which is manufactured by Witte, Inc. of Washington, New Jersey. The dust remover or dust extractor removes fiber balls that are formed in the conveyor drier and bolt mixer. These fiber balls are preferably returned to the pulp hydroformer for recirculation. The presence of fiber balls in the granules is unpleasant, but does not obstruct the effectiveness of the granules. The granules made in accordance with this process are easily compressible when placed on the floor and stepped on by a worker. The following table shows a comparison of the compressible granules of this invention (referred to as COMPRESSABLE WORK FORCE) with the absorbent granules made by the process of co-pending patent application Series No. 08 / 929,601 (referred to as WORK FORCE), and an absorbent clay material from the owner: The values established in the table above are an average of several samples of the granules made by the process as described above. The coefficient of friction was measured in accordance with ASTM Standard C 1028-89 using a static coefficient ASM 725 of the friction tester manufactured by American Slip Meter Co. The accepted standard for non-hazardous materials is a coefficient of friction of at least 0.50, ASTM D 2047-93. The compressed samples were made by placing a sample of granules made by the process described above, and following the samples that cause some or all of the granules to disintegrate. The compressed granules were then tested as explained above. The resistance to friction of the granules is between 95 and 100%. This percentage is based on the following test procedure. A weight of 75 grams of sample is shaken on a limiting screen (60 mesh) for ten minutes and 50 grams of the retained material is then shaken in a cauldron or crucible for ten minutes with ten steel balls (5/8 inches in diameter) ). The entire 50 gram sample was then shaken on the limitation screen (60 mesh) for ten minutes. The percentage of the original 50 grams retained in the limitation screen is the friction resistance mentioned above. The granular product of this invention is particularly useful as a floor absorbent which causes it to have a relatively high bulk density when compared to the granules of higher fiber content. However, they have a high resistance to friction. While this invention has been illustrated and described in accordance with the preferred embodiments, it is recognized that variations and changes may be made therein without departing from the invention as described in the claims.It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, the content of the following is claimed as property

Claims (12)

1. A granular absorbent material characterized in that it comprises: a plurality of irregular generally spherical granules containing kaolin clay and cellulose fibers, less than 10% of the cellulose fibers in the granules having a size to be retained from a 100 mesh screen , the granules having a water absorption capacity of at least about 0.90 ml / g, and a volumetric density of at least 24 lbs / ft3, at least some of the cellulose fibers communicating between the surface of a granule and the Inside the granule, the granules have a lower resistance to compression and a resistance to friction of at least 95%.

2. The granular absorbent material according to claim 1, characterized in that the granules retain their integrity when they are wetted.

3. The granular absorbent material according to claim 1, characterized in that the granules have a porous external surface.

4. The granular absorbent material according to claim 1, characterized in that the granules have a distribution size in which less than 60% of the granules have a size of 16 meshes or greater.

5. The granular absorbent material according to claim 1, characterized in that the granules have a capacity for oil absorption of at least about 0.80 ml / g.

6. A granular absorbent material characterized in that it comprises: a plurality of generally irregular spherical granules containing kaolin clay and cellulose fibers, less than 10 percent of the fibers in the granules are sized to be retained in a 100 mesh screen, granules have a resistance to friction of at least 95 percent and are compressible under the foot when they extend on the floor, the granules when compressed have a coefficient of friction of about 0.59.

7. A process for manufacturing a compressible, wastepaper absorbent flooring material, characterized in that it comprises: (a) forming a pulp slurry from the waste paper containing kaolin clay and papermaking fibers; (b) sieving the slurry so as to produce an acceptable stream containing papermaking fibers and producing a reject stream that includes water and kaolin clay; (c) driving the slurry to a flotation clarifier to produce a concentrated stream having a solids content of about 3-9 percent; (d) dewatering the concentrated stream to form a filter cake having a solids content of between about 35 and 55 percent; (e) decomposing the filter cake from a dewatering step to form granular material; (f) drying the granules to produce granules having a solids content of at least 90 percent; and (g) passing the dried granules from the drying step through a pin mixer.

8. The process according to claim 7, characterized in that the dewatering step includes passing the concentrated stream through a band press.

9. The process according to claim 8, characterized in that it includes passing the concentrated stream through another press after the band press.

10. The process according to claim 7, characterized in that the drying step includes passing the granular material through a conveying dryer having a moving belt and flowing hot air through the belt.

11. The process according to claim 7, characterized in that it includes passing the dried granules from the pin mixer through a size sorter to selectively remove larger and smaller granules.

12. The process according to claim 11, characterized in that it includes passing the granules of the classifier through a dust repeller.