MATERIAL FOR NEUTRALISING AND/OR HARDENING LIQUIDS, A METHOD FOR PRODUCING SAME, AND USES

Abstract

The invention relates to a material comprising at least 97% by weight alkaline earth metal carbonates having a calcium oxide content of 0.3% by weight or less and a particle size group of 0.1 to 1.8 mm. The invention furthermore relates to a method for the preparation thereof and also the use thereof for deacidification, filtration and/or hardening of liquids.

Claims

1-24. (canceled)

25. A method for deacidifying, filtering, or hardening a liquid comprising contacting the liquid with a material for deacidification, filtration and/or hardening liquids, comprising at least 97% by weight alkaline earth metal carbonates, wherein the free calcium oxide content of the material, determined according to the DIN EN 12485:2010-08 standard, is 0.3% by weight or less, and the particle size group of the material, determined according to the DIN EN 12902:2005-02 standard, is from 0.5 to 1.6 mm, wherein the oversized and undersized content of the particle size group of the material is 10 wt % or less, based on the total weight of the material with the particle size group, wherein the material is in the form of granules in the liquid.

26. The method of claim 25, wherein the liquid comprises impurities of iron, magnesium, or both.

27. The method of claim 26, wherein the liquid is water.

28. The method of claim 25, wherein the specific surface area of the granules is at least 3.5 m.sup.2/g as determined according to the BET method ISO 9277 standard.

29. The method of claim 25, wherein the specific surface area of the granules is 3.5-5.5 m.sup.2/g.

30. The method of claim 25, wherein the specific surface area of the granules is at least 4-5 m.sup.2/g.

31. The method of claim 25, wherein the specific surface area of the granules is 5.8 m.sup.2/g.

Description

EXAMPLE 1

Preparation of the Material According to the Invention in the Form of Granules

[0082] 60% by weight limestone powder and 40% by weight white hydrated lime are homogeneously mixed. The mixture is fed via a metering device to a granulating machine. After addition of water in proportions by mass of about 10 to 15% by weight, based on the total amount of limestone powder, white hydrated lime and water, granules are produced. The particle size can be arbitrarily selected, for example from 0.5 to 5 mm. Preference is given to a particle size of ca. 1 to 3 mm. The granulate thus prepared is placed in a drum reactor and recarbonatated by introducing gas containing carbon dioxide heated to about 180? C. having a proportion by volume of carbon dioxide >30% by volume.

[0083] The free calcium oxide present in the granulate is converted to calcium carbonate by carbon dioxide. In this case, the granulate is heated to a temperature of 110? C. after an appropriate recarbonation period. The recarbonation is continued until a calcium oxide content of about 2% by weight is present in the granulate. After completion of the reaction, the batch is fed to a filter system and sieved to a particle size group of 0.5 to 1.6 mm.

[0084] The free calcium oxide present in the granulate is converted to calcium carbonate by carbon dioxide. In this case, the granulate is heated to a temperature of 110? C. after an appropriate recarbonation period. The recarbonation is continued until a calcium oxide content of about 2% by weight is present in the granulate. After completion of the reaction, the batch is fed to a filter system and sieved to a particle size group of 0.5 to 1.6 mm.

[0085] Subsequently, the granules are heated to a temperature of 110? C. in a second recarbonation step. The recarbonation is continued for 3 hours until a calcium oxide content of only 0.3% by weight or less is present.

EXAMPLE 2

Comparison Between the Inventive Granules According to Example 1 and Granules According to DE 195 03 913 A1

[0086] In the following table characteristic parameters of the inventive granules according to Example 1 and of granules produced according to the method described on page 2, in the example of DE 195 03 913 A1 are compared.

TABLE-US-00001 Granules according to page Inventive granules 2, example of DE according to 195 03 913 A1 Example 1 Chemical Calcium oxide CaO ca. 1.0% by weight 0.3% by weight composition Calcium carbonate ca. 97.5% by ca. 98.0% by weight CaCO.sub.3 weight Magnesium ca. 0.8% by weight ca. 1.2% by weight carbonate MgCO.sub.3 Fe.sub.2O.sub.3 and Al.sub.2O.sub.3 ca. 0.3% by weight ca. 0.2% by weight Silica SiO.sub.2 ca. 0.4% by weight ca. 0.3% by weight Particle size Particle size group Particle size I: 0.5-3.15 mm 0.5-1.6 mm (DIN EN 12902) Bulk density Particle size I: ca. 1.1-1.3 t/m.sup.3 (storage density) 1.25-1.30 t/m.sup.3 Consumption per g CO.sub.2 (bound) ca. 3.5 g ca. 2.5 g (including flushing losses) Hardness per g/m.sup.3 CO.sub.2 ca. 0.128 ?dH ca. 0.128 ?dH (bound) Amounts used: empty at 20 minutes 330 kg/m.sup.3 270 kg/m.sup.3 bed contact time contact time Filter material layers with open filters 1000-2000 mm 1000-2000 mm with closed filters 1500-3000 mm 1500-3000 mm Filtration rate with open filters up to 15 m/h up to 15 m/h with closed filters up to 30 m/h up to 30 m/h Physical parameters Bulk density 1.1-1.3 g/cm.sup.3 1.1-1.2 g/cm.sup.3 Specific surface area 3.4 m.sup.2/g 5.8 m.sup.2/g (BET/ISO 9277) Apparent density 2.1 cm.sup.3/g 2.1 cm.sup.3/g Strength (weight 6.4 kg 6.4 kg loading to destruction) Turbidity NTU (DIN EN ISO 0.1-0.3 0.07-0.2 7027 (C2) 2000-4) Filtration effect water having an Fe 0.2 mg/dm.sup.3 0.01 mg/dm.sup.3 content of 0.2 mg/dm.sup.3

[0087] As can be seen in the table, the inventive granules according to Example 1 are characterized by a lower calcium oxide content and a larger specific surface area as compared with the known filter material produced according to page 2 in the example of DE 195 03 913 A1.

[0088] Using the inventive material according to Example 1, it is further shown that improved consumption values per gram of bound CO2 and at the same time reduced turbidity values can be achieved. The improved filtration effect with waters containing iron is also readily seen.

EXAMPLE 3

Use of Inventive Granules According to Example 1 for Deacidification of Water by Filtration

[0089] The material in the form of granules prepared in Example 1 as a chemically reactive filter material in open and closed fixed bed filters according to standard DIN 19 605 is used in the following application fields: [0090] deacidification and filtration of spring, well and/or surface waters [0091] deacidification and filtration in combination with deferrizing and demanganizing [0092] hardening of distillate and permeate for use thereof as drinking water

[0093] In these applications, it can be shown that even when a large quantity is introduced into the filter during the start-up phase, no over-alkalization takes place.

[0094] The inventive material according to Example 1 proves to be a highly reactive filter material with which the requirements of standard DIN EN 1018 type A of the drinking water regulation and standard DIN 2000 can be met. After complete incorporation and continuous operation, no substances are released to the water which could lead to exceeding the limits of the drinking water regulation.

[0095] Moreover, the inventive material according to Example 1 ensures a safe, low-maintenance and economically favorable operation due to its high reactivity, stable particle structure and high chemical and microbiological degree of purity.