DE19520367A1 - filter - Google Patents

Abstract

The description relates to a lightweight filter in which foamed glass is bonded by polyurethane binders. This provides well units for a depth of at least 80 m even without mechanical compacting. The filter is especially suitable for obtaining drinking water from the water table in open-cast mining areas.

Description

The invention relates to a filter with a Polyurethane binder bound solid layer to frame and Raising groundwater for the treatment of industrial and drinking water or for infiltration of water into the ground and for sealing off of water veins as well as their manufacture and use.

Such filters with a flow rate of 0 to 3 m³ / min · m² are known. In DE 43 10 725, a filter is made from a Polyurethane adhesive bound solid layer of quartz sand described. It is characterized in that the polyurethane bin in addition to the polyol and the polyisocyanate organotin compound with a molecular weight of more than 600 Catalyst and a mixture of finely divided silica and / or bentonites with a thickening of alumino-silicates as Contains modifiers.

In the older application DE 44 45 382 is also from a A polyurethane binder and quartz sand made a filter. By Adding water to the polyol will increase the water permeability of the Filters greatly reduced.  

In both cases, quartz sand or gravel is used as the filter material turns. No other filter materials are mentioned. The one from it Manufactured filter materials have a heavy weight, which is what especially when transporting and assembling the wells from the individual filter elements.

Based on this state of the art, the task was Filters with lower weight and still sufficient strength to provide.

The solution according to the invention can be found in the patent claims. It consists in particular in that as a solid to be bound (Filter material) foam glass is used.

Under foam glass is a solidified glass foam with airtight ge to understand closed cells that are filled with gas. The Foam glass lies in round, preferably spherical particles in front. Their grain size is in the range from 0.2 to 16 mm, in particular others in the range of 0.5 to 4 mm. For the large particles the grain density approx. 0.25 kg / dm³ and for the smaller particles it is approximately 0.75 kg / dm³. It is preferably in the range of 0.3 to 0.5 kg / dm³. The grain strength of the glass foam particles lies in the range between 2 and 20 KM according to Ghost, especially between 10 and 15. The bulk density of the foam glass particles is in the loading range between 100 and 400 kg / m³, especially in the range of 150 up to 300 kg / m³.

The glass is inorganic glasses, which above all based on the oxides of the following metals: Si, Al, Ca, Mg, Na and K.

The glass foam can be made synthetically as well be of natural origin. In the case of natural glass foams  especially tufa. Pumice sand or can also be used - gravel and expanded clay.

The ratio of foam glass: polyurethane binder is less than 5: 1, in particular less than 3: 1.

"Polyurethane binder" means an adhesive that from polyisocyanates, polyols, catalysts, modifiers and fillers and optionally water. Is preferred used a two-component polyurethane adhesive, one low molecular weight polyisocyanate and also proportionate low molecular weight polyol that contains the other additives are mixed shortly before use.

In particular, the polyurethane adhesive is used to manufacture the known polyhydroxy polyethers of molecular weight range from 60 to 10,000, preferably 70 to 6,000 with 2 to 10 Hydroxyl groups per molecule in question. Such Polyhydroxypolyethers are carried out in a manner known per se Obtain alkoxylation of suitable starter molecules, e.g. B. from Water, propylene glycol, ethylene glycol, glycerin, trimethylolpropane. Suitable alkoxylating agents are in particular propylene oxide and possibly also ethylene oxide.

The water content is in the range from 0 to 7.5% by weight, based on the polyol component. If filters with a high water permeability liquid should be produced, the water content should be below 0.3% by weight and preferably 0% by weight. If, however, the Water flow rate should be low or practically 0, then a water content of more than 0.3% by weight must be used, in particular the other 0.5 to 2.5 wt .-%.  

So the water flow rate is 3 m³ / min · m² if 2 parts by weight of foam glass with 1 part by weight of binder without water and at 0 m³ / min · m² when the binder is 1.1% Contains water.

All polyvalent aromatic and aliphatic isocyanates. They preferably contain in Medium 2 to a maximum of 4 NCO groups. Aromatic isocyanates preferred, especially diphenylmethane diisocyanate. The Polyisocyanate is mixed with an up to 30% excess of isocyanate, based on the polyol used, preferably with a 10 to 25% excess.

The polyurethane binder contains one Polyol / water mixture and a polyisocyanate an organotin Compound with a molecular weight of more than 600 as a catalyst and a highly disperse silica and / or bentonite.

An organotin compound is used as the catalyst. An "organotin compound" means a compound with one or more Sn-C bonds. Specific compounds are: dibutyl and dioctyltin dilaurate, dioctyltin di-2-ethylhexoate, dibutyl and dioctyltin distearate, dibutyl and dioctyltin didodecylthiolate, butyl and octyltinhexyltolate () 2-thiobutyl acid (thio) - and dioctyl tin bis (thio glycolic acid 2-ethylhexoate), tributyl and trioctyl tin (thio glycolic acid 2-ethylhexoate) as well as tributyl and trioctyl tin tris (thioethylene glycol 2-ethylhexoate), tributyl and trioctyl tin bis (thioethylene glycol 2-ethylhexoate), tributyl and trioctyl tin (thioethylene glycol 2-ethylhexoate) with the general formula R _n Sn (S-CH₂CH₂OCOC₈H₁₇) _4-n , where R is an alkyl group with 4 to 8 C atoms, Bis (β-methoxycarbonyl-ethyl) tin-bis (thioethylene glycol 2-ethylhexoate, tin bis (thioglycolic acid 2-ethylhexoate), tin dilaurate, tin-didodecyl thiolate and bis (β-acetyl-ethyl) tin bis (thio ethylene glycol -2-ethylhexoate), tin bis (thioglycolic acid 2-ethylhexoate), tin dilaurate and tin didodecyl thiolate.

The organotin compounds can be used individually or in a mixture be used, in an amount of 0.001 to 0.5, before preferably 0.01 to 0.25% by weight, based on the polyol.

Under "finely divided silica" is a silica with over 99.8 wt .-% SiO₂ understood by hydrolysis of Silicon tetrachloride was produced in an oxyhydrogen flame. she is z. B. commercially available under the trademark "Aerosil".

"Bentonite" means contaminated clays that are caused by Weathering of volcanic tuffs has arisen. Especially who the products with the trademark "Bentone".

To produce filters with a high water flow rate, a "Thickening of alumino-silicates" used. The is preferred Absorber paste, especially based on castor oil. In order to moisture in the PUR components should be made harmless the. The alumino-silicate concentration depends on the he waiting moisture and is generally 1 to 12, ins particularly 2 to 8% by weight, based on the polyol.

The polyol can also 0 to 70, in particular 10 to 60 wt .-% min contain at least one filler. It’s not just for that To increase weight and volume, but also to increase the tech improve usability. These are particularly suitable Kaolin, feldspar, mica, quartz powder, barium sulfate, aluminum oxides,  Aluminum oxide hydrates and aluminum hydroxides as well as calcium carbonate both as limestone and as limestone, which can be coated. The grain size of the filler is up to 0.05 mm.

Depending on the specific applications, it may be appropriate that Stabilize polyurethane against degradation. Suitable as antioxidants up to 1.5% by weight of Irganox 1010, 1076, 3114 and 1425 from Ciba Geigy, Topanol 0 from ICI, and Goodrite 3114 from Goodrich.

Up to 1.5% by weight are particularly suitable as UV absorbers Tinuvin P, 328 and 144 (Ciba Geigy), Sanduvor VSU and 3035 (Sandoz), Chimassorb 81 from Chimosa.

Up to 1.5% by weight arrive as stabilizers of the HALS type Tinuvin 865 and 770 from Ciba Geigy, Sanduvor 3050, 3051 and 3052 from Sandoz and Chimassorb 119 from Chimosa as well Mark LA 62, 63, 67 and 68 from Argus Chemical Corporation in Question.

The composition and quantity of the binder must be high the grain size of the foam glass, especially its dust content and on the specific conditions of use, especially the strength and the water flow rate can be adjusted. So she demands Grain reduction increasingly requires a special modification of the binder.

Under specific operating conditions, the Screen lines of the geological material of an aquifer Roger that. By grading the grain classifications accordingly, as described above, this is usually done using a Gravel fill between aquifer and filter a laminar Groundwater flow reached in the well. It works  Wall of the filter described as a second gravel fill and ver strengthens the effect of laminar flow.

The weight ratio of foam glass: polyurethane binder is preferably less than 5: 1, in particular equal to or less than 3: 1.

The filter material generally consists of 60 to 75% by weight Foam glass and 25 to 40% by weight of polyurethane adhesive. Of the Polyurethane adhesive generally consists of 50 to 99% by weight on isocyanate / polyol reaction resin, which may be water contains 0.001 to 0.5% by weight of organotin compounds, 0.03 to 2.5% by weight of silica and / or bentonite, 1 to 12% by weight of alumino silicates and 0 to 70% by weight of fillers, wherein the polyol can contain 0 to 7.5 wt .-% water on the polyol.

The filter is preferably free of additional elements Increase in mechanical strength. So it consists of the Foam glass with its glass dust content and the polyurethane Binder system.

The geometric shape of the filter is in principle arbitrary and rich depends on the specific application. The filters can ins represent special plates or pipes. It is preferably circular cylindrical tubes with a manageable Length. Diameter and thickness depend on the size and length of the well made from it.

The filters are made by using a foam glass the amount of glass dust added to the polyurethane binder system puts. Preferably, the two polyurethane components that  Contain catalysts and modifiers, initially common sam mixed and then added to the foam glass. Now the Ge quantity intimately mixed and put into a mold. After that, click on a Temperature of over 120 ° C, in particular to a temperature between between 125 and 150 ° C for a maximum of 10 minutes. Without cooling is removed from the mold. The filters obtained in this way can cool down Room temperature can be used immediately, d. H. they can drink water without further treatment be used.

The curing process according to the invention is therefore very economical economical, because conventional polyurethane adhesives take a long time to harden times at temperatures above 100 ° C, if that Filtrate should have drinking water quality.

The filters according to the invention are suitable for the extraction of industrial and Drinking water from groundwater or for infiltration of water into the ground. Due to the freely adjustable water penetration rates can be built that connect different Exclude aquifers by adding aquifers with un desired water through impermeable pipes, the so-called Solid pipes with a water permeability of 0 m³ / min · m² be built. Layers of earth with the water to be drained expanded with water-permeable filters.

However, it is also possible to irrigate the soil with the filters sern, e.g. B. by making infiltration wells. By installation of pipes with water flow rates close to 0 m³ / min · m² is here infiltration is only possible in selected soil layers.

The use of the filter according to the invention using Foam glass with a fine grain fraction of less than 0.25 mm in diameter  allowed - particularly advantageous in combination with Polyol / water mixtures - the manufacture of filters with under different water penetration rates, and at relatively low Costs due to the low consumption of polyurethane bin determine.

Use foam glass instead of sand or gravel increases the weight of the filter by a factor of up to approx. 5. The Fe Stability in the wet state is reduced by only one factor from approx. 2.  

The invention will now be explained in detail by means of examples tert:

example 1 Production of a filter tube with foamed glass particles

The resin component consists of
53 parts of a difunctional polypropylene glycol with an OH number of approx. 280,
8 parts of a trifunctional polypropylene glycol with an OH number of approx. 380,
29.17 parts of a kaolin,
8.00 parts of sodium aluminum silicate in castor oil (1: 1 mixture),
0.03 parts of dibutyltin dilaurate and
1.8 parts Bentone 34.

(The details are parts by weight.)
The hardener component consists of diphenylmethane-4,4-diisocyanate. 100 parts by weight of the resin are mixed with 55 parts by weight of the hardener at about 20 ° C. using a dynamic mixer and then mixed in a screw mixer with twice the amount of foamed glass particles with a particle size between 1 and 4 mm.

These are glass particles with the trade name Poraver (manufacturer: Dennert Poraver GmbH 96130 Schlüsselfeld, Federal Republic of Germany Germany). It becomes a 1: 1 mixture of these particles with a Grain size distribution 1 to 2 mm (grain density 0.40 ± 0.07 kg / dm³) and 2 to 4 mm (grain density 0.34 ± 0.06 kg / dm³) used.

This batch is put into a tube shape with a length of 1 m brought and cured at 135 ° C for 9 minutes. After that time leaves  the filter tube can be removed from the mold practically without cooling, without sticking to the mold wall.

After the filter tube has cooled down to room temperature, it is instant term use at a defined water flow rate according to the selected Grain classification possible. According to the example described the water flow rate is approx. 3 m³ / min · m².

The filter tube weighs 18 kg. A corresponding filter pipe with sand as filter material weighs 70 kg.

Claims (13)

1. Filter made of a layer of solid material bound with a polyurethane binder to hold and raise groundwater for the preparation of industrial and drinking water or for infiltration of water into the ground as well as for sealing off water veins, as characterized in that the bound solid ( Filter material) is a foam glass. 2. Filter according to claim 1, characterized in that the Foam glass has a spherical shape with a grain size of 0.25 to 16 mm, in particular from 0.5 to 4 mm. 3. Filter according to claim 1 or 2, characterized by a grain apparent density of the foam glass particles from 0.2 to 0.7, in particular from 0.3 to 0.5 kg / dm³. 4. Filter according to claim 1, 2 or 3, characterized in that the foam glass is an inorganic glass, which in particular contains the following metal oxides: Si, Al, Ca, Mg, Na and K. 5. Filter according to at least one of claims 1 to 4, characterized characterized in that the polyurethane binder in addition to the Polyol / water mixture and the polyisocyanate an organotin Compound with a molecular weight of more than 600 as a catalyst and a mixture of finely divided silica and / or Contains bentonite. 6. Filter according to at least one of claims 1 to 5, characterized characterized by Aerosil as highly disperse silica and by Bentone as bentonite.   7. Filter according to at least one of claims 1 to 6, characterized characterized by the quantity ratio of foam glass Polyurethane binders of less than 5: 1, in particular equal to or less than 3: 1. 8. Filter according to at least one of the claims, characterized records that the foam glass with a grain size up to 6 mm, in particular up to 4 mm, a dusty portion under 0.25, in particular between 0.06 and 0.2 mm in diameter holds. 9. Filter according to at least one of claims 1 to 8, characterized characterized in that for the production of filters with low Water flow rate the water content in the polyol 0.3 to 7.5, is in particular 0.5 to 2.5% by weight. 10. Filter according to at least one of claims 1 to 8, characterized characterized in that for the production of filters with high What water flow rate in the polyol below 0.3% by weight lies, which is preferably by adding a thickening of Alumino silicates is achieved. 11. Cylindrical filter according to at least one of claims 1 to 10, characterized by a circular cross section and the lack of additional elements to increase mechanical strength.   12. Production of the filter according to at least one of claims 1 to 11, characterized

• a) by mixing the components of foam glass with a defined fine dust fraction and polyurethane binding system,
• b) by subsequently filling molds with this mixture and
• c) by curing at temperatures of more than 120 ° C, preferably at temperatures between 125 to 150 ° C and
• d) by demolding without cooling.

13. Use of the filter according to at least one of claims 1 to 12 for the production of wells for drainage in opencast mines offer, for the production of wells for drinking water, for the drainage of construction pits and for the infiltration of water for irrigation and for sealing off water veins.