US1609759A - Clarification of bleach liquors - Google Patents
Clarification of bleach liquors Download PDFInfo
- Publication number
- US1609759A US1609759A US14576A US1457625A US1609759A US 1609759 A US1609759 A US 1609759A US 14576 A US14576 A US 14576A US 1457625 A US1457625 A US 1457625A US 1609759 A US1609759 A US 1609759A
- Authority
- US
- United States
- Prior art keywords
- lime
- bleach
- liquor
- suspended
- liquors
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000007844 bleaching agent Substances 0.000 title description 35
- 238000005352 clarification Methods 0.000 title description 5
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 29
- 235000011941 Tilia x europaea Nutrition 0.000 description 29
- 239000004571 lime Substances 0.000 description 29
- ZKQDCIXGCQPQNV-UHFFFAOYSA-N Calcium hypochlorite Chemical compound [Ca+2].Cl[O-].Cl[O-] ZKQDCIXGCQPQNV-UHFFFAOYSA-N 0.000 description 9
- 239000000725 suspension Substances 0.000 description 9
- 238000005660 chlorination reaction Methods 0.000 description 8
- 238000000034 method Methods 0.000 description 6
- 229910052500 inorganic mineral Inorganic materials 0.000 description 5
- 239000011707 mineral Substances 0.000 description 5
- 235000010755 mineral Nutrition 0.000 description 5
- 238000010908 decantation Methods 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 238000000926 separation method Methods 0.000 description 4
- 238000003860 storage Methods 0.000 description 4
- 239000011362 coarse particle Substances 0.000 description 3
- 238000001914 filtration Methods 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- 239000007900 aqueous suspension Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 239000003513 alkali Substances 0.000 description 1
- MCOQHIWZJUDQIC-UHFFFAOYSA-N barban Chemical compound ClCC#CCOC(=O)NC1=CC=CC(Cl)=C1 MCOQHIWZJUDQIC-UHFFFAOYSA-N 0.000 description 1
- 238000004061 bleaching Methods 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 239000000920 calcium hydroxide Substances 0.000 description 1
- 235000011116 calcium hydroxide Nutrition 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- SNICXCGAKADSCV-UHFFFAOYSA-N nicotine Chemical compound CN1CCCC1C1=CC=CN=C1 SNICXCGAKADSCV-UHFFFAOYSA-N 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 239000006228 supernatant Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B11/00—Oxides or oxyacids of halogens; Salts thereof
- C01B11/04—Hypochlorous acid
- C01B11/06—Hypochlorites
- C01B11/064—Hypochlorites of alkaline-earth metals
Definitions
- This invention relates'to the clarification of calcium hypochlorite liquors such as are used in the pulp and paper industries for bleaching.
- Such bleach liquors are com monly made either by dissolving bleaching powder in water or by chlorinating suspensions of lime in water.
- Commercial bleaching powder always contains some excess free lime, and, when the bleaching powder is dissolved, this free lime, excepting the small amount dissolved, is suspended in the solutionwWhen the bleach liquor is prepared by chlorinating a suspension of lime, an excess of lime is used to produce a stable liquor and to facilitate control of the chlorinating operation.
- the lime employed may also contain other associated insoluble mineral matter, and where bleaching powder is used insoluble impurities such as calcium carbonate may also be present,
- insoluble impurities such as calcium carbonate may also be present.
- the bleach liquors, as commonly prepared always contain some suspended lime 1n varymg degrees of SlllJ-CllVlSlOIl and frequently contain other insoluble impurities.
- the bleach liquor has been resorted to for effecting separation of finely divided suspended lime.
- a part of the lime present is in a. very fine state of sub-division and it is particularly this very finely divided material which will not settle out readily that causes trouble, both in removal and in subsequentuse oi the bleach liquor it it is not removed.
- bleach liquor is clarified by chlorinating the finely divided suspended eras Application filed March w, 1925. Serial No. 14,576.
- the method offthe invention is applicable to bleach liquors prepared either by solution of bleaching powder or by chlor ination of lime suspensions, but it is particularly eiiective in the clarification of chlorinated suspensions containing an ex cess of lime.
- the bleach liquor may be initially prepared in the customary Way and in the concentrationscommonly used. After initial preparation of the bleach liquor, for example, either by dissolving bleaching powder in Water or by chlorinating an aqueous suspension of lime, e. g. milk of lime, it may be settled for a relatively short period and the coarse suspended matter so precipitated then separated from the liquor. While the very finely divided susupended lime requires a very long if not an indefinite period to settle, the coarse particles of suspended material settle comparatively rapidly and, only a com-.'
- the period of settling may be reduced to one-half or less of that now commonly employed.
- the partially clarified liquor is removed, as by decantetion.
- the extreme precaution hitherto required in such operations may also be relaxed here because of the subsequent chlorination operation.
- the partially clarified bleach liquor then contains in suspension the finely divided lime particles which will not settle out readily.
- the bleach liquor which is then turbid is then chlorinated until the remaining lime in suspension goes into solution.
- the present invention provides an improved method for eliminating free undissolved lime from bleach liquor, and consequently of overcoming the difficulties encountered in the application of such bleach liquors in the pulp and paper industry.
- the invention effects a substantial saving in time and also reduces the storage capacity required in any given instance.
- the invention substantially increases the capacity of any existing bleach liquor plant. The time required .and the storage capacity required may be reduced as much as 50% or more.
- the invention also enables the production of bleach liquor free from suspended free lime to a degree hitherto approached only by. filtration methods but without requiring the carrying out of such operations.
- the process of the invention moreover, may be carried out in existing bleach liquor plants without substantial modifica tion. It will be apparent that the invention is of more or less general application to the clarification of bleach liquors where the elimination of free undissolved lime is de sirable.
- An improvedmethod of clarifying calcium hypochlorite bleach liquors containing suspended mineral matter including lime which comprises separating from the bleach liquor coarse-particles of suspended mineral matter and subsequently chlorinating the separated liquor until the remaining finely divided suspended lime dissolves, without carrying the chlorinat on beyond neutrality.
- An improved method of preparing bleach liquors which comprises chlorinating an aqueous suspension containing an excess of lime, separating from the chlorinated liquor coarse particles of suspended mineral matter, and subsequently further chlorinating the separated liquor until the remaining finely divided suspended lime dissolves, Without carrying the chlorination beyond neutrality.
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Inorganic Chemistry (AREA)
- Paper (AREA)
Description
Fatenteel Dec. 7, rue.
U T 1? T d JAMES DOUGLAS MACMAHON, 0F NIAGARA FALI4S, NEW YORK, ASSIGNGR TO THE .MATHIESON ALKALI WORKS, OF NEW YORK. N. 521, A CORPORATION OF VIRGINIA.
CLIFICATIUN 0F BLEACH LIQUORS.
No Drawing.
This invention relates'to the clarification of calcium hypochlorite liquors such as are used in the pulp and paper industries for bleaching. Such bleach liquors are com monly made either by dissolving bleaching powder in water or by chlorinating suspensions of lime in water. Commercial bleaching powder always contains some excess free lime, and, when the bleaching powder is dissolved, this free lime, excepting the small amount dissolved, is suspended in the solutionwWhen the bleach liquor is prepared by chlorinating a suspension of lime, an excess of lime is used to produce a stable liquor and to facilitate control of the chlorinating operation. The lime employed may also contain other associated insoluble mineral matter, and where bleaching powder is used insoluble impurities such as calcium carbonate may also be present, The result is that the bleach liquors, as commonly prepared, always contain some suspended lime 1n varymg degrees of SlllJ-CllVlSlOIl and frequently contain other insoluble impurities.
ln the pulp and paper industry it has been found that such suspended mineral matter, and particularly free. undissolved lime, is seriously detrimental to the eliective use of the bleach liquors. To overcome this difficulty it has been customary to subject the bleach liquor, after solution of the bleaching powder or chlorination of the lime suspension, to long periods of settling, followed by decantation of the supernatant liquor lromthe precipitated residue. Not only have such methods involved large storage capacity in the bleach liquor plant but extreme precaution is necessary in the decantation operation, and, no matter how carefully the .decantation is made, or how long the period of settling, a certain per centage ol" finely divided lime always re mains in suspension in the bleach liquor. in some cases even filtration ot the bleach liquor has been resorted to for effecting separation of finely divided suspended lime. A part of the lime present is in a. very fine state of sub-division and it is particularly this very finely divided material which will not settle out readily that causes trouble, both in removal and in subsequentuse oi the bleach liquor it it is not removed. According the present invention, the
, bleach liquor is clarified by chlorinating the finely divided suspended eras Application filed March w, 1925. Serial No. 14,576.
after an initial separation of the coarse suspended material without carrying the chlorination beyond neutrality. A clear stable bleach liquor, free from undissolved tree lime, can thus be produced, while the long periods of settling and large storage capacity and the extreme precaution in decantation or the filtration hitherto required are. eliminated. The method offthe invention is applicable to bleach liquors prepared either by solution of bleaching powder or by chlor ination of lime suspensions, but it is particularly eiiective in the clarification of chlorinated suspensions containing an ex cess of lime. p
In carrying out the invention, the bleach liquor may be initially prepared in the customary Way and in the concentrationscommonly used. After initial preparation of the bleach liquor, for example, either by dissolving bleaching powder in Water or by chlorinating an aqueous suspension of lime, e. g. milk of lime, it may be settled for a relatively short period and the coarse suspended matter so precipitated then separated from the liquor. While the very finely divided susupended lime requires a very long if not an indefinite period to settle, the coarse particles of suspended material settle comparatively rapidly and, only a com-.'
paratively brief period is required,.for example, the period of settling may be reduced to one-half or less of that now commonly employed. Following the separation at coarse suspended particles the partially clarified liquor is removed, as by decantetion. The extreme precaution hitherto required in such operations may also be relaxed here because of the subsequent chlorination operation. The partially clarified bleach liquor then contains in suspension the finely divided lime particles which will not settle out readily.
The bleach liquor, which is then turbid is then chlorinated until the remaining lime in suspension goes into solution. The
very finely divided lime ditficult if not impossible to remove completely by the methods hitherto employed, is thus dissolved by the chlorination operation without the necessity of prolonged settling and careful decanta due to free undissolved lime in suspension, m
effect a complete separation of the coarse material in the initial clarification is also corrected by the chlorination operation. The chlorination is not carried beyond neutrality. A clarified stable bleach liquor free from undissolved free lime is thus produced.
It will thus be seen that the present invention provides an improved method for eliminating free undissolved lime from bleach liquor, and consequently of overcoming the difficulties encountered in the application of such bleach liquors in the pulp and paper industry. The invention effects a substantial saving in time and also reduces the storage capacity required in any given instance. Conversely, the invention substantially increases the capacity of any existing bleach liquor plant. The time required .and the storage capacity required may be reduced as much as 50% or more. The invention also enables the production of bleach liquor free from suspended free lime to a degree hitherto approached only by. filtration methods but without requiring the carrying out of such operations. The process of the invention, moreover, may be carried out in existing bleach liquor plants without substantial modifica tion. It will be apparent that the invention is of more or less general application to the clarification of bleach liquors where the elimination of free undissolved lime is de sirable.
I claim: I
1. An improvedmethod of clarifying calcium hypochlorite bleach liquors containing suspended mineral matter including lime, which comprises separating from the bleach liquor coarse-particles of suspended mineral matter and subsequently chlorinating the separated liquor until the remaining finely divided suspended lime dissolves, without carrying the chlorinat on beyond neutrality.
2. An improved method of preparing bleach liquors, which comprises chlorinating an aqueous suspension containing an excess of lime, separating from the chlorinated liquor coarse particles of suspended mineral matter, and subsequently further chlorinating the separated liquor until the remaining finely divided suspended lime dissolves, Without carrying the chlorination beyond neutrality.
In testimony whereof I aflix my signature.
JAMES DOUGLAS MAQMAHON.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US14576A US1609759A (en) | 1925-03-10 | 1925-03-10 | Clarification of bleach liquors |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US14576A US1609759A (en) | 1925-03-10 | 1925-03-10 | Clarification of bleach liquors |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US1609759A true US1609759A (en) | 1926-12-07 |
Family
ID=21766324
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US14576A Expired - Lifetime US1609759A (en) | 1925-03-10 | 1925-03-10 | Clarification of bleach liquors |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | US1609759A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4175038A (en) * | 1978-07-21 | 1979-11-20 | Olin Corporation | Purification of waste streams containing available chlorine |
-
1925
- 1925-03-10 US US14576A patent/US1609759A/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4175038A (en) * | 1978-07-21 | 1979-11-20 | Olin Corporation | Purification of waste streams containing available chlorine |
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