Project TE 118, existing example A16
Level/Categories
CL 1a, 1b, 2a, 2b3
AL 1a, 1b, 2a, 2b3
Documents (Classification is based on GB 1278886)
GB 1 278 886
FR 2 059 104 A5
DE 1 942925 A1
Short Version of the Disclosure
The process for purification of aqueous H2SiF6 solutions is disclosed. Phosphate ions are
removed from an aqueous solution of H2SiF6 by (a) adding at least sufficient Fe3+ ions to give
Fe3+ in the same molar proportion as the phosphate ions, (b) maintaining the solution at 60 to
100 degrees while adding gaseous ammonia until the pH is 2-4 and (c) removing the
precipitated iron phosphate formed. Further ammonia may be added until the pH is 8 to 9
whereby SiO2·H2O is precipitated and can be separated from the ammonium fluoride.
Invention Information
I1: Process for the purification of an aqueous H2SiF6 solution consisting of the following steps,
(a) adding at least sufficient Fe3+ ions to give Fe3+ in the same molar proportion as the
phosphate ions, (b) maintaining the solution at 60 to 100 degrees while adding gaseous
ammonia until the pH is 2-4 and (c) removing the precipitated iron phosphate formed (see
claim 1-6,8).
I2: Process for the preparation of a substantially phosphate-free solution of NH4F, including
the further following steps, (d) adding ammonia until the pH is 8 to 9 (e) separating
precipitated SiO2·H2O (see claim7).
I3: Aqueous H2SiF6 solution substantially free from phosphate, prepared by the above process
(see claim 9).
Identification of Potential Subclasses
Subject Matter
Tool
I1,I3
Catchword Index
I2
As above
Query
inorganic compounds of FLUORINE
FLUORO silicates
inorganic ACID(S)
IPC Places
C01B
C01B 33/10
C01
ammonium salts
inorganic compounds of FLUORINE
C01C
C01B
1
Analysis and Selection of Classification Symbols
Core Level
I1: No specific place for the process of the preparation of this compound is available,
therefore this invention information should be classified in the place for the compound, as
defined in paragraph 95 of the Guide.
No specific place is available for classification of the acid as such. It should be classified as a
compound containing silicon, fluorine and other elements, the fluorosilicic acid H2SiF6
containing hydrogen as another element. As this is a compound of non-metallic elements,
subclass C01B is appropriate. Main group C01B 33/00 (silicon; compounds thereof) and
C01B 7/00 (halogen; halogen acids) are candidates. Because the last place priority rule is
applied in the range of subclasses C01B-C01G and within each of these subclasses, as
indicated in Note (1) after the title of class C01, C01B 33/00 is the correct classification place.
Separation of the phosphate occurs in form of iron (III) phosphate, but the phosphate is just a
by-product to be removed and not of sufficient importance to merit a classification.
I2: No specific place for the process of the preparation of this compound is available,
therefore this invention information should be classified in the place of the compound as
defined in paragraph 95 of the Guide.
Because ammonium fluoride is one of the halides of ammonium, subclasses C01B (nonmetallic elements; compounds thereof) and C01C (ammonia; cyanogens; compounds thereof)
are candidates. The last place priority rule as applied in subclass C01 as shown in Note (1)
after C01, indicates that subclass C01C is appropriate. Additionally, as the reference in C01B
9/00, which is a classification symbol for general methods of preparing halides, states
“ particular individual halides, see the relevant groups in subclasses C01B-C01G according to
the element combined with the halogen”, subclass C01C is appropriate. C01C 1/00 is
obviously the correct classification place for ammonium fluoride.
I3: No specific place is available for classification of the acid as such. It should be classified
as a compound containing silicon, fluorine and other elements, the fluorosilicic acid H2SiF6
containing hydrogen as another element. This is a compound of non-metallic elements.
Therefore, C01B is appropriate. Main group C01B 33/00 (silicon; compounds thereof) and
C01B 7/00 (halogen; halogen acids) are candidates. Because of the last place priority rule as
applied in C01 as shown in Note (1) after C01, C01B 33/00 is the correct classification.
C01B 33/10 should be listed first because the most important feature of this invention is the
specified process for preparation of aqueous H2SiF6 free from phosphate and C01B 33/10
most adequately represents this feature.
Advanced Level
I1: No specific place for the process of the preparation of this compound is available,
therefore this invention information should be classified in the place for the compound, as
defined in paragraph 95 of the Guide.
No specific place is available for classification of the acid as such. It should be classified as a
compound containing silicon, fluorine and other elements, the fluorosilicic acid H2SiF6
containing hydrogen as another element. As this is a compound of non-metallic elements,
2
subclass C01B is appropriate. Main group C01B 33/00 (silicon; compounds thereof) and
C01B 7/00 (halogen; halogen acids) are candidates. Because the last place priority rule
applies in the range of subclasses C01B-C01G and within each of these subclasses, as
indicated in Note (1) after the title of C01, C01B 33/10 covers compounds containing silicon,
fluorine and other elements. Thus C01B 33/10 is the correct classification, which is
subdivision of C01B 33/08 covering compounds containing halogen.
Separation of the phosphate occurs in form of iron (III) phosphate, but the phosphate is just a
by-product to be removed and not of sufficient importance to merit a classification.
I2: No specific place for the process of the preparation of this compound is available,
therefore this invention information should be classified in the place of the compound as
defined in paragraph 95 of the Guide.
Because ammonium fluoride is one of the halides of ammonium, subclasses C01B (nonmetallic elements; compounds thereof) and C01C (ammonia; cyanogens; compounds thereof)
are candidates. The last place priority rule as applied in C01 as shown in Note (1) after C01,
indicates that subclass C01C is appropriate. Additionally, as the reference in C01B 9/00,
which is a classification symbol for general methods of preparing halides, states “ particular
individual halides, see the relevant groups in subclasses C01B-C01G according to the element
combined with the halogen”, subclass C01C is appropriate. Ammonium fluoride is classified
within C01C according to the last place priority rule. C01C 1/16 covers all halides of
ammonium. Thus C01C 1/16 is the correct classification.
I3: No specific place is available for classification of the acid as such. It should be classified
as a compound containing silicon, fluorine and other elements, the fluorosilicic acid H2SiF6
containing hydrogen as another element. This is a compound of non-metallic elements.
Therefore, C01B is appropriate. Main group C01B 33/00 (silicon; compounds thereof) and
C01B 7/00 (halogen; halogen acids) are candidates. Because of the last place priority rule as
applied in C01 as shown in the Note (1) after C01, C01B 33/10 covers compounds containing
silicon, fluorine and other elements. Thus C01B 33/10 is the correct classification, which is a
subdivision of C01B33/08 covering compounds containing halogen. Separation of the
phosphate occurs in form of iron (III) phosphate, but the phosphate is just a by-product to be
removed and not of sufficient importance to merit a classification.
C01B 33/10 should be listed first because the most important feature of this invention is the
specified process for preparation of aqueous H2SiF6 free from phosphate and C01B 33/10
most adequately represents this feature.
Subject
Matter
Analysis of Subclass
Selection
Subclass
Analysis of Group Selection
IPC CL
IPC (2006)
IPC AL
I1,I3
Subclass title covers
subject-matter
C01B
Last place priority rule (Note (1)
after C01)
C01B 33/00
C01B 33/10
(2006.01)
I2
Subclass title covers
subject-matter
C01C
Last place priority rule (Note (1)
after C01)
C01C 1/00
C01C 1/16
(2006.01)
Complete Classification
The complete core and advanced level classification for this document based on the above
analysis is as follows:
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Core Level
Int. Cl. (2006)
C01B 33/00
C01C 1/00
Advanced Level
Int.Cl.
C01B 33/10 (2006.01)
C01C 1/16 (2006.01)
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