Chemistry of inorganic compounds – Silicon or compound thereof – Oxygen containing
Patent
1998-08-26
2000-11-07
Griffin, Steven P.
Chemistry of inorganic compounds
Silicon or compound thereof
Oxygen containing
423326, 423332, 423334, C01B 3324, C01B 3332, C01B 3320
Patent
active
061432660
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method for producing crystalline inorganic silicate builders useful for ion exchangers and alkalizers.
BACKGROUND ART
Since silicate builders have alkaline buffering properties, they are highly useful for detergent builders. Particularly, since the silicate builders in crystalline forms have excellent cationic exchange capacities, they are greatly useful for detergent builders.
Among methods for producing the silicate builders, Japanese Patent Laid-Open No. 5-66888 discloses a method using water glass as a starting material. In this method, a crystalline sodium silicate having a layered structure is produced by a method comprising the steps of spray-drying a water glass solution to form amorphous sodium silicate, and heating the resulting amorphous sodium silicate in a firing zone while recirculating a portion of the product. However, this method requires drying off large amounts of the water content from the water glass, which makes it disadvantageous from an energy-saving viewpoint.
Japanese Patent Laid-Open No. 6-72008 discloses a method for directly baking the glassy product to solve the above problems. In this method, crystalline sodium silicate is produced by the steps of pulverizing a water glass product obtainable by cooling a fused mixture of sand and soda, and then heating the pulverized product. However, in this method, since the resulting product comprises a two-component system of Na.sub.2 O--SiO.sub.2, the control of the crystalline system becomes difficult, rendering its performance as an ion exchange material for detergents unsatisfactory. Also, a large amount of heat energy is consumed upon glassification, thereby making it disadvantageous from an energy-saving viewpoint.
In view of the above problems, an object of the present invention is to provide a method for easily producing a high-performance silicate builder using inexpensive silica sand as a starting material.
These and other objects of the present invention will be apparent from the following description.
DISCLOSURE OF THE INVENTION
In sum, the present invention pertains to the following: following composition in its anhydrous form: relationships: y/x is 1.0 to 4.0, z/y is not more than 1.0, M stands for Na and K, K/Na is 0.01 to 2.0, and Me stands for Ca and/or Mg, the method comprising the steps of: at least one member of Ca-containing compounds and Mg-containing compounds to silica sand, to give a mixture; following composition in its anhydrous form: y/x is 1.0 to 4.0, M stands for Na and K, and K/Na is 0.01 to 2.0, the method comprising the steps of: silica sand, to give a mixture;
BEST MODE FOR CARRYING OUT THE INVENTION
The method for producing a crystalline inorganic builder having a particular composition, comprising the steps of: and optionally at least one member of Ca-containing compounds and Mg-containing compounds to silica sand, to give a mixture;
In other words, the method is characterized by the incorporation of potassium and optionally alkaline earth metals into the above crystalline inorganic silicates using inexpensive silica sand and by specific preparation conditions of the materials for baking. The method of the present invention will be explained in detail below.
The crystalline inorganic silicates in the present invention have the following compositions: and z are numerical values satisfying the following relationships: y/x is 1.0 to 4.0, z/y is not more than 1.0, M stands for Na and K, K/Na is 0.01 to 2.0, and Me stands for Ca and/or Mg. are numerical values satisfying the following relationship: y/x is 1.0 to 4.0, M stands for Na and K, and K/Na is 0.01 to 2.0.
It is desired that the silica sand usable in the present invention has an SiO.sub.2 content of not less than 90% by weight, preferably not less than 95% by weight, more preferably not less than 97% by weight. Concrete examples of these silica sands include pearl sand and flattery sand produced in Australia; Sarawak sand produced in Indonesia; silica sand prepared by disintegrating silica
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patent: 5084262 (1992-01-01), Novotny et al.
patent: 5238668 (1993-08-01), Novotny et al.
patent: 5356607 (1994-10-01), Just
patent: 6027560 (2000-06-01), Sakaguchi et al.
Jyono Masaharu
Otsuka Kazuhiro
Sakaguchi Mikio
Sakamoto Ichiro
Griffin Steven P.
Ildebrando Christina
Kao Corporation
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