CS275988B6 - Filtration textile - Google Patents

Abstract

Solutions for ui— ' especially for pressure filtration for filter presses for dewatering sludge from chemical čirsnia. sewage treatment, whereas the filter fabric comprises an active fiber synthetic staple blend component fibers that are needling associated with a thermoplastic thin layer nonwoven fabric and synthetic backing. Heat exposure is generated Highly smooth film.

Description

The invention relates to a filter fabric which is part of a filter unit intended in particular for sludge presses for the dewatering of sludge from the chemical treatment of waste water in the textile industry.

At present, polyamide woven tarpaulins are predominantly used in presses. Polyamide tarpaulins have high strength in the transverse and longitudinal directions, but their permeability is low, which causes relatively fast fabric tightening.

Clogging of the fabric proportionally prolongs the filling time of the press and reduces the filtration efficiency? filter unit. Therefore, it is necessary to wash the woven tarpaulins regularly after removing the sludge cake, which is a demanding manual work. In most cases, sailing is abandoned and, if possible, exchanged for new ones.

Because the presses work batchwise, after each work cycle, the sludge cake is removed by hand, which is also a strenuous job. As the woven tarpaulins do not have a highly smooth surface, the sludge compact adheres to the surface of the tarpaulin. .

The described disadvantages are eliminated by the filter filter, the essence of which is that it consists of a needled nonwoven fabric, in particular of a profiled fabric, to which a thin layer of thermoplastic nonwoven fabric and a synthetic fabric is attached by needling. By heat treatment of this formation, a highly smooth permeable film is formed on its surface.

Very good efficiency of the filter fabric is achieved by means of the active ingredient, which consists of a (transversely formed) fibrous web formed by a mixture of synthetic staple fibers, in particular polypropylene fibers. Profiled fibers are particularly advantageous for the formation of the nonwoven layer, on the ground that they have a large specific surface area, which is also reflected in the specific surface area of the needled nonwoven layer. The advantage is the use of a mixture of fibers of different weight. This creates an internal porous structure of the nonwoven layer which is suitable for separating the coagulated solid particles from the liquid phase. The optimal porosity of the fleece layer is regulated by the number of punctures per 1 cm, for this reason there is no disproportionate damage to the fibers in the fleece due to the large number of punctures.

The dimensional stability of the filter fabric is ensured by a light synthetic fabric, which does not reduce the filtering efficiency of the fabric, as it forms its outer outer layer.

The smooth permeable film on the surface of the fabric means, on the one hand, that filtration through the textile does not cause it to become trapped by solid particles and does not reduce the filtration efficiency, and on the other hand, the sludge compact does not stick to the filter fabric. This partially eliminates the manual work of emptying the press.

The advantage of the filter fabric according to the invention is in particular its high efficiency and durability, as evidenced by the tests carried out during the dewatering of sludge in the sewage treatment plant sludge presses.

The advantages of the invention are described but not limited by the following examples:

Example no. 1

The fiber layer weighing 400 gm “ ^2, consisting of a mixture of polypropylene fibers with a weight of 2.8 dtex and 6.7 dtex, is reinforced by needling with a number of 25 needles per 1 cm. with the simultaneous penetration of the fiber bundles into a thermoplastic nonwoven fabric with a weight of 70 gm. This unit is needled in a synthetic base with the number of needles 2 per 1 cm. The thermoplastic layer is melted to form a porous surface structure.

Example no. 2 —2

The formed fiber layer, weighing 550 g.m, of polypropylene profiled fibers with a weight of 3.9 dtex and 6.7 dtex, is reinforced by needling with a number of 15 needles per 1 cm, while at the same time the bundles of fibers penetrate into the thermoplastic nonwoven fabric of

CS 275 988 86 2

-2 Λ weight 100 g.m. By needling, these layers are bonded to a synthetic backing, and a smooth permeable film is formed on the surface of the fabric by applying heat to the thermoplastic nonwoven fabric.

Example No. 3

From a mixture of polypropylene high-arc fibers with a weight of 1.3 dtex 10 and 2.8 dtex, a fibrous layer weighing 250 gm is formed, reinforced by needling with a number of needles of 50 per 1 cm. At the same time, the combined needle-e of a thermoplastic non-woven fabrics _- 2 weight of 50 gm. The layers thus joined are joined by needling with a synthetic fabric, • 2 ·· the number of needles 50 per 1 cm, while the bundles of fibers up to a height of 1 mm penetrate into the synthetic fabric. The mold is heat treated to form a High Smooth Permeable Film on its surface.

Claims (1)

PATENT CLAIMS Filtration fabrics, intended primarily for sludge presses for dewatering sludges from chemical wastewater treatment, are characterized in that the active layer consists of a needled nonwoven fabric of a mixture of synthetic staple fibers, in particular profiled staple fibers, which is needled together with a thin layer of thermoplastic nonwoven fabric and a synthetic backing, wherein a highly smooth permeable film is formed on the surface of the fabric on the thermoplastic layer by thermal exposure.