METHOD FOR PRODUCING FUNCTIONALLY IMPROVED CARBOLIME

Abstract

The present invention relates to a method for producing functionally improved carbolime from carbolime, and also functionally improved carbolime, which can be produced according to the inventive method, and the use of functionally improved carbolime as filtering aid, as filler, as lime fertilizer or as adsorbent for the adsorption of dyes.

Claims

1-13. (canceled)

14. A method for producing functionally improved carbolime from carbolime, comprising the following method steps: a) providing a carbolime having an average particle size of no more than 20 m, containing at least 85% by weight CaCO.sub.3 and no more than 1% by weight organic non-sugar substances (each DS (dry substance), based on the DS of the carbolime); b) carbonatating the carbolime; c) removing a dye-containing liquid phase from the carbonatated carbolime to obtain a precursor of functionally improved carbolime; and d) obtaining the functionally improved carbolime.

15. The method according to claim 14, wherein a dilution of the carbolime is carried out between method steps a) and b), between method step b) and c) or between method steps a) and b) as well as b) and c).

16. The method according to claim 14, wherein the functionally improved carbolime obtained in method step d) is obtained from the precursor of functionally improved carbolime obtained in method step c) by means of at least one membrane filter press.

17. The method according to claim 14, wherein the functionally improved carbolime obtained in method step d) has a CaCO.sub.3 content of at least 90% by weight (DS, based on the functionally improved carbolime).

18. The method according to claim 14, wherein, subsequent to method step c), Ca(OH).sub.2 is added to the precursor of functionally improved carbolime obtained in method step c).

19. The method according to claim 14, wherein the carbolime provided in method step a) has a dry substance content of 55 to 80% by weight (based on the total weight of the carbolime).

20. The method according to claim 14, wherein the carbolime used for the carbonatation in method step b) has a dry substance content of 25 to 40% by weight (based on the total weight of the carbolime to be carbonatated).

21. The method according to claim 14, wherein the carbonated carbolime, which is fed to the removal in method step c), has a dry substance content of 15 to 30% by weight (based on the total weight of the carbonatated carbolime).

22. The method according to claim 14, wherein the functionally improved carbolime obtained in method step d) has a dry substance content of 85 to 95% by weight (based on the total weight of the functionally improved carbolime).

23. The method according to claim 14, wherein the carbolime used in method step a) is a colloid-reduced carbolime.

24. Functionally improved carbolime, producible by a method according to claim 1.

25. Use of the functionally improved carbolime according to claim 24 as a filtering aid, as a filler, as a lime fertilizer or as an adsorbent for the adsorption of dyes.

26. Use of the functionally improved carbolime according to claim 14 for juice purification.

Description

[0069] The present invention is illustrated based on the following examples and figures.

[0070] FIG. 1 schematically shows a method for producing carbolime suitable for use in the method according to the invention; and

[0071] FIG. 2 schematically shows the method steps carried out for the production of functionally improved carbolime from carbolime.

EXAMPLE 1

1. Production of Functionally Improved Carbolime

1.1 Production of Carbolime Suitable for Use in the Method According to the Invention

[0072] a) Preliming

[0073] 30 kg of sugar beet raw juice are added to a heatable container having a volume of 50 1, which comprises a stirrer, a CO.sub.2 inlet tube and a pH electrode, and the mixture is heated to 55 C. Over a period of 20 minutes, milk of lime is gradually added to the raw juice, up to the pH value of the optimum flocculation point of the preliming step (approximately 0.1 to 0.3 g CaO/100 ml of juice). To increase the settling rate, a polyanionic flocculation aid (AN 945) is subsequently added. The formed clear supernatant (clarified juice) is drawn off into a storage container. The preliming coagulate formed is drained and fed to a membrane filter press or decanter centrifuge.

[0074] b) Main Liming

[0075] 25 g of clarified juice are added to the cleaned, heatable container and mixed with milk of lime, up to an alkalinity of 0.6 g of CaO/100 ml of juice. The juice temperature is then raised to 85 C. This temperature is maintained for 20 minutes.

[0076] c) First Carbonatation

[0077] By introducing CO.sub.2, the pH value is lowered to 11.2 over a period of 15 min

[0078] d) First Filtration

[0079] The carbonatated juice is transferred to a 30-liter pressure filter and filtered. The filtration coefficient of the first carbonation juice obtained is less than 0.5 s/cm.sup.2.

[0080] e) Second Carbonatation

[0081] The filtered juice is transferred into the cleaned, heatable container and heated to 95 C. By introducing CO.sub.2, the pH is lowered to 9.2.

[0082] f) Second Filtration

[0083] The carbonatated juice is transferred to a 30-liter pressure filter and filtered. A second carbonation juice and thin juice are obtained.

[0084] g) Separation of Carbolime

[0085] The carbonation juices (steps d) and f)) obtained from the first and second carbonation steps (steps c) and e)) by means of filtration are combined and pressed by means of membrane filter presses to obtain carbolime. The carbolime obtained has a CaCO.sub.3 content of 86%, a particle size of the CaCO.sub.3 crystals of <20 m and an amount of organic non-sugar substances of approximately 1% (DS, based on DS of the carbolime).

[0086] 1.2 Production of Functionally Improved Carbolime from Carbolime

[0087] First, the colliod-free carbolime according to section 1.1, having a CaCO.sub.3 content of 86%, a particle size of the CaCO.sub.3 crystals of <20 m and a quantity of organic non-sugars of approx. 1%, is suspended with condensate (the use of water is also possible) to obtain a carbolime suspension having a solids content of approximately 30 to 35% dry substance. The resulting suspension was heated to approximately 80 C. and then gassed (carbonatated) with carbon dioxide to reduce the pH value of the suspension. The pH value endpoint was 8.5 after gassing with carbon dioxide. The resulting suspension was then diluted with condensate (the use of water is also possible) to a dry substance content of 25%, and the solids fraction is removed from the dye-containing liquid phase by decantation (other suitable separation methods, such as filtration or centrifugation are also possible). The obtained precursor of functionally improved carbolime had a CaCO.sub.3 content of 93%.

[0088] The obtained precursor of functionally improved carbolime can subsequently be pressed either directly by means of membrane filter presses to obtain functionally improved carbolime or be used to produce activated functionally improved carbolime according to Example 2.

EXAMPLE 2

[0089] Production of Activated Functionally Improved Carbolime

[0090] In order to activate the functionally improved carbolime (CaCO.sub.3 content of 93%) from Example 1, fresh milk of lime (Ca(OH).sub.2) was added to the precursor obtained from functionally improved carbolime having a dry substance content of approx. 35%, to set a pH value of approx. 11 and then pressed by means of membrane filter presses.