EP0178729A1
Expired / Lapsed
EP
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Method for rapid controlled coating of the inner surface of pipes with a tenacious calcite lining
Assignee: Mekorot Water Co Ltd
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Filing: 1985-10-09
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Granted: —
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Expires: 2005-10-09
Abstract
Abstract The present invention relates to a method for obtaining a tenacious in-situ coating deposition of calcite on the inner surface of water pipes at very high rates. The calcite producing ingredients are supplied to the water stream in quantities supplementing concentrations available in the natural water used, giving the required supersaturation levels by addition of suitable salts to provide an aqueous lining solution supersaturated with respect to calcium carbonate containing dissolved calcium and carbonate ions. The method consists in maintaining the suspended calcium carbonate particles concentrations in the lining solution below 300 ppm, the excess suspended particles being removed by physical means. The calcite coating deposition according to the present invention has the advantage that it occurs at the rate of above 5 microns/h and even above 50 microns/h, maintaining a completely corrosion-free system during the coating. The method is applicable to lead pipes, cement mortar linings or asbestos pipes.
Inventors
- 👤 David Hasson
- 👤 Mordechai Karmon
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 15:11
CPC Classifications
C; C23; C23F; C23F11/00; C23F11/08; C23F11/18
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
182 words
A method for obtaining an improved deposition of calcite linings of above 50 micron thickness on the inner surfaces of pipes, said lining occuring at the rate of above 5 microns/h, being tenacious with 3 bulk densities of above 1.5 gr/cm , the lining resulting by delivering through said pipes at a flow velocity of above 1 m/sec an aqueous lining solution supersaturated with respect to CaCO containing dissolved 3 calcium and carbonate ions each at a concentration level of above about 80 ppm (expressed as CaCO ), maintaining substantially stoichiometric 3 + + concentrations of the CO and Ca ions, said lining being produced by 3 dosage of calcium and carbonate ions producing ingredients supplied in amounts providing initial supersaturations, corresponding to lining solution compositions that would be maintained in the absence of CaCO +2 3 precipitations at levels above 200 ppm Ca and above 200 ppm of -2 CO , characterized by the fact that the suspended CaCO particles 3 3 concentrations in the lining solution is less than 300 ppm, the excess suspended particles being removed by physical means.
Claim 2
Independent Claim
182 words
A method for obtaining an improved deposition of calcite linings of above 50 micron thickness on the inner surfaces of pipes, said lining occuring at the rate of above 5 microns/h, being tenacious with 3 bulk densities of above 1.5 gr/cm , the lining resulting by delivering through said pipes at a flow velocity of above 1 m/sec an aqueous lining solution supersaturated with respect to CaCO containing dissolved 3 calcium and carbonate ions each at a concentration level of above about 80 ppm (expressed as CaCO ), maintaining substantially stoichiometric 3 + + concentrations of the CO and Ca ions, said lining being produced by 3 dosage of calcium and carbonate ions producing ingredients supplied in amounts providing initial supersaturations, corresponding to lining solution compositions that would be maintained in the absence of CaCO +2 3 precipitations at levels above 200 ppm Ca and above 200 ppm of -2 CO , characterized by the fact that the suspended CaCO particles 3 3 concentrations in the lining solution is less than 300 ppm, the excess suspended particles being removed by physical means.
Claim 3
Dependent Claim
22 words
A method according to Claim 1, wherein the suspended CaCO 3 particles concentrations in the lining solution is less than 150 ppm.
Claim 4
Independent Claim
19 words
A method according to Claims 1 or 2, wherein the excess of suspended particles are removed by filtration equipment.
Claim 5
Independent Claim
25 words
A method according to Claims 1 or 2, wherein the excess of suspended CaCO particles are removed by gravity sedimentation in a 3 holding vessel.
Claim 6
Independent Claim
21 words
A method according to Claims 1 or 2, wherein the excess of suspended particles are removed by clarifying or filtration centrifuges.
Claim 7
Independent Claim
94 words
A method according to Claims 1 to 5, wherein the calcium carbonate producing ingredients of the lining solution are formed from added streams of a soluble calcium salt and dissolved Ca(OH) or a mixture 2 thereof on the one hand and a soluble carbonate salt, a soluble bicarbonate salt, an alkali and CO gas or a mixture thereof on the other 2 hand, the addition aiming to provide controlled initial calcium and carbonate concentrations which are roughly equal and a controlled pH of the residual supersaturation, giving substantially equal residual calcium and carbonate concentrations.
Claim 8
Dependent Claim
18 words
A method according to Claim 6, where the streams added are composed of CaCl , 00 and NaOH.
Claim 9
Dependent Claim
28 words
2 2 8. A method according to Claim 6, where the streams added are composed of CaCl , Na CO , NaHCO and NaOH. 2 2 3 3
Claim 10
Dependent Claim
18 words
A method according to Claim 6, where the streams added are composed of CO and Ca(OH) 2 2
Claim 11
Independent Claim
15 words
A method according to Claims 6 to 9, said added streams consisting of concentrated reagents.
Claim 12
Dependent Claim
20 words
A method according to Claim 1 to 10, where the flow rate of the lining solution is above 2.0 m/sec.
Claim 13
Independent Claim
23 words
A method according to Claims 1 to 10, where the initial supersaturation conditions are above 1500 ppm calcium and above 1500 ppm carbonate.
Claim 14
Independent Claim
21 words
A method according to Claims 1 to 12, where the suspended particles in the lining solution are less than 50 ppm.
Claim 15
Independent Claim
47 words
A method according to Claims 7 or 9, where part or all of the CO is injected to the entrance of or inside a particles separation 2 device, to lower the pH at which lining solution clarification is made, the lowered pH being maintained below pH 8.5.
Claim 16
Independent Claim
21 words
A method according to Claims 1 to 14, wherein the lining is carried out at temperatures up to 80 degrees centigrade.
Claim 17
Dependent Claim
24 words
A method according to Claim 15, wherein the lining is carried at a temperature in the range of 20 degrees to 60 degrees centigrade.
Claim 18
Independent Claim
17 words
A method according to Claims 1 to 16, applied to internal surfaces of iron and steel pipes.
Claim 19
Dependent Claim
25 words
A method according to Claim 17, wherein alkali metal sulfite in amounts above 100 ppm are incorporated into the lining solution circulated during calcite lining.
Claim 20
Independent Claim
25 words
A method according to Claims 1 to 18, wherein various known additives for water treatment are incorporated in the lining solution circulated during calcite lining.
Claim 21
Dependent Claim
21 words
A method according to Claim 19, wherein said additives are selected from the group consisting of sodium phosphates and alkali polyphosphates.
Claim 22
Independent Claim
24 words
A method according to Claims 1 to 20, wherein small amounts of silicates are also incorporated into the lining solution circulated during calcite lining.
Claim 23
Independent Claim
12 words
A method according to Claims 1 to 21, applied to lead pipes.
Claim 24
Independent Claim
13 words
A method according to Claims 1 to 21, applied to cement mortar linings.
Claim 25
Dependent Claim
14 words
24 . A method according to Claims 1 to 21, applied to asbestos pipes.
References Cited (Backward Citations)
GB260233A
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US1683521A
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GB299073A
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US2299748A
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US3640759A
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EP0008211A1
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