EP0152336B1 - Process for directing and accelerating the formation of concretions in a marine environment and apparatus for carrying it out - Google Patents
Process for directing and accelerating the formation of concretions in a marine environment and apparatus for carrying it out Download PDFInfo
- Publication number
- EP0152336B1 EP0152336B1 EP85400167A EP85400167A EP0152336B1 EP 0152336 B1 EP0152336 B1 EP 0152336B1 EP 85400167 A EP85400167 A EP 85400167A EP 85400167 A EP85400167 A EP 85400167A EP 0152336 B1 EP0152336 B1 EP 0152336B1
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- EP
- European Patent Office
- Prior art keywords
- elements
- cathode
- anode
- brucite
- electrical connection
- 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
Links
- 238000000034 method Methods 0.000 title claims description 17
- 230000015572 biosynthetic process Effects 0.000 title claims description 6
- 229910052751 metal Inorganic materials 0.000 claims description 25
- 239000002184 metal Substances 0.000 claims description 25
- 229910052599 brucite Inorganic materials 0.000 claims description 20
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 claims description 13
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 6
- 229910045601 alloy Inorganic materials 0.000 claims description 6
- 239000000956 alloy Substances 0.000 claims description 6
- 230000008021 deposition Effects 0.000 claims description 6
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims description 5
- 238000004090 dissolution Methods 0.000 claims description 5
- 229910052749 magnesium Inorganic materials 0.000 claims description 5
- 239000011777 magnesium Substances 0.000 claims description 5
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 4
- 230000002269 spontaneous effect Effects 0.000 claims description 4
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 3
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 3
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 3
- 229910052782 aluminium Inorganic materials 0.000 claims description 3
- 229910052791 calcium Inorganic materials 0.000 claims description 3
- 239000011575 calcium Substances 0.000 claims description 3
- 229910052742 iron Inorganic materials 0.000 claims description 3
- 229910001092 metal group alloy Inorganic materials 0.000 claims description 3
- 239000012209 synthetic fiber Substances 0.000 claims description 3
- 229920002994 synthetic fiber Polymers 0.000 claims description 3
- 239000011701 zinc Substances 0.000 claims description 3
- 239000004020 conductor Substances 0.000 claims description 2
- 239000000835 fiber Substances 0.000 claims description 2
- 239000000945 filler Substances 0.000 claims description 2
- 239000012212 insulator Substances 0.000 claims description 2
- 239000000463 material Substances 0.000 claims description 2
- 230000002093 peripheral effect Effects 0.000 claims description 2
- 238000003466 welding Methods 0.000 claims description 2
- 229910052725 zinc Inorganic materials 0.000 claims description 2
- 239000004411 aluminium Substances 0.000 claims 1
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 11
- 239000013535 sea water Substances 0.000 description 7
- 238000004210 cathodic protection Methods 0.000 description 5
- 239000013078 crystal Substances 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 238000010276 construction Methods 0.000 description 3
- 239000003792 electrolyte Substances 0.000 description 3
- 229910000838 Al alloy Inorganic materials 0.000 description 2
- 229910000861 Mg alloy Inorganic materials 0.000 description 2
- 229910001297 Zn alloy Inorganic materials 0.000 description 2
- 229910000019 calcium carbonate Inorganic materials 0.000 description 2
- 238000002425 crystallisation Methods 0.000 description 2
- 230000008025 crystallization Effects 0.000 description 2
- ZOMNIUBKTOKEHS-UHFFFAOYSA-L dimercury dichloride Chemical class Cl[Hg][Hg]Cl ZOMNIUBKTOKEHS-UHFFFAOYSA-L 0.000 description 2
- 229910052500 inorganic mineral Inorganic materials 0.000 description 2
- 239000011707 mineral Substances 0.000 description 2
- 239000004576 sand Substances 0.000 description 2
- 230000006641 stabilisation Effects 0.000 description 2
- 238000011105 stabilization Methods 0.000 description 2
- 241001125840 Coryphaenidae Species 0.000 description 1
- 206010013647 Drowning Diseases 0.000 description 1
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005137 deposition process Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 description 1
- 239000000347 magnesium hydroxide Substances 0.000 description 1
- 229910001862 magnesium hydroxide Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000002787 reinforcement Effects 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02B—HYDRAULIC ENGINEERING
- E02B17/00—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor
- E02B17/0017—Means for protecting offshore constructions
- E02B17/0026—Means for protecting offshore constructions against corrosion
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D9/00—Electrolytic coating other than with metals
- C25D9/04—Electrolytic coating other than with metals with inorganic materials
- C25D9/08—Electrolytic coating other than with metals with inorganic materials by cathodic processes
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02B—HYDRAULIC ENGINEERING
- E02B3/00—Engineering works in connection with control or use of streams, rivers, coasts, or other marine sites; Sealings or joints for engineering works in general
- E02B3/04—Structures or apparatus for, or methods of, protecting banks, coasts, or harbours
Definitions
- the present invention relates to the formation of calcareous concretions in the marine environment and more generally in an amphoteric electrolyte such as sea water, containing at least magnesium, calcium and carbonate ions.
- cathodic protection methods by sacrificial anodes in which, to protect a metal surface, in general a ferrous metal, against corrosion of sea water, it is immersed in the water of sea or brings into contact with sea water in contact with the surface to be protected, a short distance from the latter, an anode electrode of a metal or a metal alloy having a spontaneous potential more electro-negative than the metal to be protected and for example in aluminum, zinc or magnesium alloys.
- the ratio of the surface of the anode electrode to the surface to be protected is approximately 1/50 to 1 / 500th and the cathode current densities are of the order of 10- 3 A / m 2 to 0.5 A / m 2 so that the lifespan of the anodes is long, the protection being ensured during said lifespan.
- brucite is produced in the form of large crystals with a porous structure and a low electrical resistivity while a low cathodic current density gives a deposit of small crystals with an impermeable structure and a high electrical resistivity.
- the brucite with coarse crystallization dissolves in sea water while maintaining inside its mass a high pH corresponding to a pH of active deposition of aragonite. After removal of the anodic potential, the predominantly brucite deposit is transformed under certain conditions into a predominantly aragonite concretion.
- the object of the present invention is to create, by the electrolytic deposition process known as sacrificial anodes, used in cathodic protection, a large layer of a predominantly large crystal brucite deposit giving a porous mass with a high water content capable of then transform into a concretion dominated by aragonite.
- This object is achieved, in accordance with the invention, by using a metal cathode whose shape corresponds to the skeleton of the concretion to be obtained and an anode of a metal or metal alloy more electro-negative than the metal or the alloy of the cathode, by immersing the anode and the cathode in the marine environment containing magnesium, calcium and carbonate ions and by electrically interconnecting the two electrodes, the method according to the invention being characterized in.
- the ratio of the surface of the anode to the surface of the cathode is between 1/30 and 2/1, with an anode mass sufficient to maintain this ratio inside the say limits during the period necessary for the deposition of the brucite-dominated concretion under the desired thickness.
- the density of the cathode current is greater than 0.5 A / m 2 and generally 1 A / m 2 and the pH in contact with the cathode is greater than 9, 5, which results in a predominantly brucite deposit.
- the period during which the anode, which gradually loses weight and surface area, continues to have a surface ratio greater than 1/30, depends on the resistivity and therefore in part on the salinity of the electrolyte which may be sea water, brackish water or water made artificially saline.
- Brucite depending on the conditions of the deposit and in particular the speed, dissolves more or less quickly when the pH drops as a result of the reduction in the density of the cathode current.
- the speed of dissolution of the brucite risks being so high that the slow growth of the aragonite crystals does not allow filling of the dissolution voids.
- a cathodic current density ensuring a pH below the dissolution pH of the brucite but greater than the pH of the marine environment by means of a second sacrificed anode having a surface ratio at the surface of the cathode lower than that between 1/30 and 2/1, having ensured the deposition of the brucite-dominant concretion.
- the spontaneous potential of steel in sea water at a temperature varying from 5 to 20 ° C, with a pH close to 8.20 and a salinity of 35% is between -800 and -1350 m V per relation to the reference electrode to the saturated calomel (DHW) according to the cathode current density applied.
- the metal of the anode can be either an aluminum alloy with an electro-negative potential close to -1100 m V (ECS), a zinc alloy with an electro-negative potential close to -1050 m V (ECS) or a magnesium alloy with an electro-negative potential of around -1500 m V (DHW).
- the cathode and the anode are in direct electrical contact, the elements forming the anode, for example bars or wires being inserted in a network of elements of corresponding shape forming the cathode with contacts distributed within the network.
- the conditions imposed by the process mean that, in order to obtain the necessary cathodic current density, cathode elements whose cross section is greater than a minimum must be used. Consequently, in the network, the cathode elements have a significant spacing. However, it is often advantageous to increase the volume of the predominantly brucite deposit or its mechanical strength, which cannot be ensured by cathode elements with large spacing and, in accordance with the invention, this result is achieved by incorporating into the network forming the device, inert fillers, for example sand, natural or synthetic fibers. It also falls within the framework of the process of drowning at least the cathode in a porous mass of inert elements, for example sands or fibers, this mass being impregnated by the marine environment.
- the present invention also relates to a device for implementing the method in order to form a concretion in the marine environment, this device comprising a structure of ferrous metal corresponding to the skeleton of the concretion to be formed, elements of a metal or alloy having a more electro-negative spontaneous potential than iron with an electrical connection between said structure and said elements, device characterized in that the electrical connection does not include a current source and the ratio of the surface of said elements to the surface of the structure being between 1/30 and 2/1.
- the elements can be in the form of wires, bars, blades or bars or in the form of plates.
- the electrical connection can be provided by an intermediate conductor electrically connected to the ferrous metal structure and to the element (s). It can also be direct, the elements being secured directly to the ferrous metal structure, for example by welding or mechanical tightening, so as to ensure said electrical connection.
- the element When the element is in the form of a blade, or a plate of almost constant thickness, it preferably has an additional thickness forming a core whose peripheral surface is less than 1 / 30th of the surface surface of the structure, the electrical connection being provided on said core.
- several types of elements are provided which have thicknesses perpendicular to their surface surfaces, which are variable, the total of the surface surfaces of the thickest elements being less than approximately one thirtieth of the surface surface of the structure. These last two characteristics are intended to leave after consumption of the thin part of the element which. ensures the predominant deposition of brucite, an anodic electro-negative element slowing down the dissolution of brucite and favoring the concretion of the mass of brucite by aragonite.
- the ferrous metal structure is mechanically secured to electrically inert materials in a porous form such as sand enclosed in a porous envelope, natural or synthetic fibers, tubes or perforated sheaths , etc.
- the ferrous metal structure having to have a low electrical resistance therefore a large section, section also necessary to allow the sinking in sandy bottoms, but a reduced surface in contact with the electrolyte to have a high density of cathode current, it is possible to sheath the structure with an insulator, reserving exposed areas according to rings, bands or braces for fixing the predominantly brucite deposit.
- the anode element can be applied in the form of pads outside the sheath with direct electrical contact through the insulation.
- the method and the device are capable of receiving numerous applications.
- a first application is the accelerated construction of artificial underwater reefs, the skeleton of the reef being made of ferrous metal, for example in wires or iron bars with plates or bars of magnesium and / or aluminum fixed by being distributed in the structure.
- a second application is the stabilization of the seabed such as the sandy bottom intended to receive constructions, this stabilization being able to be done either by sinking in the porous sandy mass, according to a network, of electrodes forming cathodes and anodes with the electrical interconnections or elongate element comprising both the cathode surfaces and the anode elements, either by forming a surface concretion in carpet by extending on the bottom a mesh or latticework welded in ferrous metal with associated anode elements.
- a third application of great interest economical is the filling of cracks and clogging of joints in marine structures such as submerged or submerged dikes, various basins, etc. by inserting into the cracks or joints of an element in the form of a ribbon, a twist or the like comprising elements of ferrous metal and elements of aluminum, zinc or their alloys.
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Mechanical Engineering (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Ocean & Marine Engineering (AREA)
- Environmental & Geological Engineering (AREA)
- Inorganic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Prevention Of Electric Corrosion (AREA)
Description
La présente invention concerne la formation de concrétions calcaires en milieu marin et plus généralement dans un électrolyte amphotère tel que l'eau de mer, contenant au moins des ions magnésium, calcium et carbonates.The present invention relates to the formation of calcareous concretions in the marine environment and more generally in an amphoteric electrolyte such as sea water, containing at least magnesium, calcium and carbonate ions.
Dans US-A-4 246 075, on a proposé de former de telles concrétions en connectant une source de courant électrique continu entre une cathode formant le noyau de la concrétion et une ou plusieurs anodes disposées au voisinage de la cathode. Ce procédé assure la formation sur la cathode d'un dépôt minéral.In US-A-4 246 075, it has been proposed to form such concretions by connecting a source of direct electric current between a cathode forming the nucleus of the concretion and one or more anodes arranged in the vicinity of the cathode. This process ensures the formation on the cathode of a mineral deposit.
Ce procédé exige toutefois une source d'alimentation en courant continu connectée aux électrodes. Il est évident que la présence obligatoire d'une alimentation en courant continu constitue une limitation importante pour l'application du procédé.However, this process requires a DC power source connected to the electrodes. It is obvious that the compulsory presence of a DC power supply constitutes an important limitation for the application of the method.
On connaît, d'autre part, les procédés dits de protection cathodique par anodes sacrifiées dans lesquels, pour protéger une surface en métal, en général un métal ferreux, contre la corrosion de l'eau de mer, on immerge dans l'eau de mer ou met en contact avec l'eau de mer au contact de la surface à protéger, à faible distance de cette dernière, une électrode anodique en un métal ou un alliage métallique présentant un potentiel spontané plus électro-négatif que le métal à protéger et par exemple en alliages d'aluminium, de zinc ou de magnésium. Le rapport de la surface de l'électrode anodique à la surface à protéger est d'environ 1/50 à 1 /500ème et les densités de courant cathodique sont de l'ordre de 10-3 A/m2 à 0,5 A/m2 de sorte que la durée de vie des anodes est longue, la protection étant assurée pendant la dite durée de vie.On the other hand, so-called cathodic protection methods by sacrificial anodes are known, in which, to protect a metal surface, in general a ferrous metal, against corrosion of sea water, it is immersed in the water of sea or brings into contact with sea water in contact with the surface to be protected, a short distance from the latter, an anode electrode of a metal or a metal alloy having a spontaneous potential more electro-negative than the metal to be protected and for example in aluminum, zinc or magnesium alloys. The ratio of the surface of the anode electrode to the surface to be protected is approximately 1/50 to 1 / 500th and the cathode current densities are of the order of 10- 3 A / m 2 to 0.5 A / m 2 so that the lifespan of the anodes is long, the protection being ensured during said lifespan.
Une étude détaillée du mécanisme de la protection cathodique en milieu marin a conduit à l'explication qu'il se produit sur la surface de la cathode une couche mince constistuée principalement par de l'aragonite ou carbonate de calcium finement cristallisé ainsi que le sont aussi les autres minéraux présents, couche qui augmente la résistance électrique entre la cathode et l'eau de mer. Lorsque cette couche mince se trouve détruite mécaniquement, elle se reforme sous l'influence du couple électrolytique existant entre l'anode et la cathode. Le phénomène mis en oeuvre dans la protection cathodique semblait s'opposer à la formation de couches concrétionnées sous des épaisseurs importantes du fait notamment de la production d'une couche peu perméable à cristallisation fine.A detailed study of the mechanism of cathodic protection in the marine environment has led to the explanation that there occurs on the surface of the cathode a thin layer consisting mainly of aragonite or finely crystallized calcium carbonate as are also the other minerals present, a layer which increases the electrical resistance between the cathode and seawater. When this thin layer is destroyed mechanically, it is reformed under the influence of the electrolytic couple existing between the anode and the cathode. The phenomenon implemented in cathodic protection seemed to oppose the formation of concreted layers under significant thicknesses due in particular to the production of a thinly permeable layer with fine crystallization.
Une étude des structures des couches et une étude comparative du phénomène de concrétion en milieu marin tel que décrit dans US-A-4 246 075 et du phénomène de protection cathodique, ont conduit à l'observation que, selon la valeur du pH, il se produisait préférentiellement un dépôt de brucite (hydroxyde de magnésium) pour un pH voisin et supérieur à 9,5 alors que, pour un pH inférieur, il peut se produire un dépôt d'aragonite (carbonate de calcium). En outre l'expérience a montré qu'avec une densité de courant cathodique élevée donnant un dépôt rapide, il se produit de la brucite sous forme de grands cristaux avec une structure poreuse et une résistivité électrique faible alors qu'une densité de courant cathodique faible donne un dépôt de petits cristaux avec une structure imperméable et une résistivité électrique élevée. En outre en l'absence d'un couple galvanique, la brucite à cristallisation grossière se dissout dans l'eau de mer en maintenant à l'intérieur de sa masse un pH élevé correspondant à un pH de dépôt actif de l'aragonite. Après suppression du potentiel anodique, le dépôt à dominante brucite se transforme sous certaines conditions en une concrétion à dominante aragonite.A study of the structures of the layers and a comparative study of the phenomenon of concretion in the marine environment as described in US-A-4 246 075 and of the phenomenon of cathodic protection, led to the observation that, according to the value of the pH, it a deposit of brucite (magnesium hydroxide) preferably occurs for a pH close to and greater than 9.5 whereas, for a lower pH, there can be a deposit of aragonite (calcium carbonate). Furthermore, experience has shown that with a high cathodic current density giving a rapid deposition, brucite is produced in the form of large crystals with a porous structure and a low electrical resistivity while a low cathodic current density gives a deposit of small crystals with an impermeable structure and a high electrical resistivity. In addition, in the absence of a galvanic couple, the brucite with coarse crystallization dissolves in sea water while maintaining inside its mass a high pH corresponding to a pH of active deposition of aragonite. After removal of the anodic potential, the predominantly brucite deposit is transformed under certain conditions into a predominantly aragonite concretion.
La présente invention a pour but de créer, par le procédé de dépôt électrolytique dit par anodes sacrifiées, utilisé en protection cathodique, une couche importante d'un dépôt à prédominance de brucite à gros cristaux donnant une masse poreuse à forte teneur en eau susceptible de se transformer ensuite en une concrétion à dominante d'aragonite.The object of the present invention is to create, by the electrolytic deposition process known as sacrificial anodes, used in cathodic protection, a large layer of a predominantly large crystal brucite deposit giving a porous mass with a high water content capable of then transform into a concretion dominated by aragonite.
Ce but est atteint, conformément à l'invention, en mettant en oeuvre une cathode métallique dont la forme correspond au squelette de la concrétion à obtenir et une anode en un métal ou alliage métallique plus électro-négatif que le métal ou l'alliage de la cathode, en immergeant l'anode et la cathode dans le milieu marin contenant des ions magnésium, calcium et carbonates et en interconnectant électriquement les deux électrodes, le procédé selon l'invention étant caractérisé en ce .qu'on n'impose pas de courant entre les deux électrodes et que le rapport de la surface de l'anode à la surface de la cathode est compris entre 1/30 et 2/1, avec une masse de l'anode suffisante pour maintenir ce rapport à l'intérieur des dites limites pendant la période nécessaire au dépôt de la concrétion à dominante de brucite sous l'épaisseur recherchée.This object is achieved, in accordance with the invention, by using a metal cathode whose shape corresponds to the skeleton of the concretion to be obtained and an anode of a metal or metal alloy more electro-negative than the metal or the alloy of the cathode, by immersing the anode and the cathode in the marine environment containing magnesium, calcium and carbonate ions and by electrically interconnecting the two electrodes, the method according to the invention being characterized in. that one does not impose any current between the two electrodes and that the ratio of the surface of the anode to the surface of the cathode is between 1/30 and 2/1, with an anode mass sufficient to maintain this ratio inside the say limits during the period necessary for the deposition of the brucite-dominated concretion under the desired thickness.
Avec le rapport ci-dessus entre les surfaces anodique et cathodique, la densité du courant cathodique est supérieure à 0,5 A/m2 et en général à 1 A/m2 et le pH au contact de la cathode est supérieur à 9,5, ce qui entraîne un dépôt à dominante de brucite. La durée pendant laquelle l'anode, qui perd progressivement du poids et de la surface, continue à présenter un rapport de surface supérieur à 1 /30, dépend de la résistivité et donc en partie de la salinité de l'électrolyte qui peut être de l'eau de mer, de l'eau saumâtre ou une eau rendue artificiellement saline.With the above ratio between the anode and cathode surfaces, the density of the cathode current is greater than 0.5 A / m 2 and generally 1 A / m 2 and the pH in contact with the cathode is greater than 9, 5, which results in a predominantly brucite deposit. The period during which the anode, which gradually loses weight and surface area, continues to have a surface ratio greater than 1/30, depends on the resistivity and therefore in part on the salinity of the electrolyte which may be sea water, brackish water or water made artificially saline.
La brucite selon les conditions du dépôt et notamment de la vitesse se dissout plus ou moins rapidement lorsque le pH s'abaisse par suite de la réduction de la densité du courant cathodique. Avec un dépôt à dominante de brucite déposé rapidement, la vitesse de dissolution de la brucite risque d'être tellement élevée que la lente croissance des cristaux d'aragonite ne permet pas d'assurer le remplissage des vides de dissolution.Brucite, depending on the conditions of the deposit and in particular the speed, dissolves more or less quickly when the pH drops as a result of the reduction in the density of the cathode current. With a predominantly deposited deposit of brucite, the speed of dissolution of the brucite risks being so high that the slow growth of the aragonite crystals does not allow filling of the dissolution voids.
Pour y remédier et selon une autre caractéristique de l'invention on maintient, après formation de la couche de dépôt à dominante de brucite d'épaisseur voulue, une densité de courant cathodique assurant un pH inférieur au pH de dissolution de la brucite mais supérieur au pH du milieu marin au moyen d'une seconde anode sacrifiée ayant un rapport de surface à la surface de la cathode inférieur à celui compris entre 1/30 et 2/1, ayant assuré le dépôt de la concrétion à dominante de brucite.To remedy this and according to another characteristic of the invention, after training is maintained of the predominantly brucite deposit layer of desired thickness, a cathodic current density ensuring a pH below the dissolution pH of the brucite but greater than the pH of the marine environment by means of a second sacrificed anode having a surface ratio at the surface of the cathode lower than that between 1/30 and 2/1, having ensured the deposition of the brucite-dominant concretion.
A titre indicatif le potentiel spontané de l'acier dans une eau de mer à température variant de 5 à 20 °C, avec un pH voisin de 8,20 et une salinité de 35% est compris entre -800 et -1350 m V par rapport à l'électrode de référence au calomel saturé (ECS) suivant la densité de courant cathodique appliquée. On peut utiliser comme métal de l'anode soit un alliage d'aluminium avec un potentiel électro-négatif voisin de -1100 m V (ECS), un alliage de zinc avec un potentiel électro-négatif voisin de -1050 m V (ECS) ou un alliage de magnésium avec un potentiel électro-né- gatifvoisin de -1500 m V (ECS).As an indication, the spontaneous potential of steel in sea water at a temperature varying from 5 to 20 ° C, with a pH close to 8.20 and a salinity of 35% is between -800 and -1350 m V per relation to the reference electrode to the saturated calomel (DHW) according to the cathode current density applied. The metal of the anode can be either an aluminum alloy with an electro-negative potential close to -1100 m V (ECS), a zinc alloy with an electro-negative potential close to -1050 m V (ECS) or a magnesium alloy with an electro-negative potential of around -1500 m V (DHW).
Selon une autre caractéristique de l'invention la cathode et l'anode sont en contact électrique direct, les élément formant l'anode, par exemple des barres ou des fils étant insérés dans un réseau d'éléments de forme correspondante formant la cathode avec des contacts répartis à l'intérieur du réseau.According to another characteristic of the invention, the cathode and the anode are in direct electrical contact, the elements forming the anode, for example bars or wires being inserted in a network of elements of corresponding shape forming the cathode with contacts distributed within the network.
Les conditions imposées par le procédé font que, pour obtenir la densité de courant cathodique nécessaire il faut mettre en oeuvre des éléments de cathode dont la section est supérieure à un minimum. En conséquence, dans le réseau, les éléments de cathode présentent un écartement notable. Or il est souvent intéressant d'augmenter le volume du dépôt à dominante brucite ou sa résistance mécanique, ce que ne peuvent assurer les éléments cathodiques à fort écartement et, conformément à l'invention, ce résultat est atteint en incorporant dans le réseau formant le dispositif, des charges inertes par exemple sables, fibres naturelles ou synthétiques. Il entre également dans le cadre du procédé de noyer au moins la cathode dans une masse poreuse d'éléments inertes, par exemple des sables ou des fibres, cette masse étant imprégnée par le milieu marin.The conditions imposed by the process mean that, in order to obtain the necessary cathodic current density, cathode elements whose cross section is greater than a minimum must be used. Consequently, in the network, the cathode elements have a significant spacing. However, it is often advantageous to increase the volume of the predominantly brucite deposit or its mechanical strength, which cannot be ensured by cathode elements with large spacing and, in accordance with the invention, this result is achieved by incorporating into the network forming the device, inert fillers, for example sand, natural or synthetic fibers. It also falls within the framework of the process of drowning at least the cathode in a porous mass of inert elements, for example sands or fibers, this mass being impregnated by the marine environment.
La présente invention a également pour objet un dispositif pour la mise en oeuvre du procédé afin de former une concrétion en milieu marin, ce dispositif comportant une structure en un métal ferreux correspondant au squelette de la concrétion à former, des éléments en un métal ou alliage présentant un potentiel spontané plus électro-négatif que le fer avec une connexion électrique entre la dite structure et les dits éléments, dispositif caractérisé en ce que la connexion électrique ne comporte pas de source de courant et le rapport de la surface des dits éléments à la surface de la structure étant compris entre 1 /30 et 2/1.The present invention also relates to a device for implementing the method in order to form a concretion in the marine environment, this device comprising a structure of ferrous metal corresponding to the skeleton of the concretion to be formed, elements of a metal or alloy having a more electro-negative spontaneous potential than iron with an electrical connection between said structure and said elements, device characterized in that the electrical connection does not include a current source and the ratio of the surface of said elements to the surface of the structure being between 1/30 and 2/1.
Les éléments peuvent être sous forme de fils, de barres, de lames ou de barreaux ou sous forme de plaquettes. La connexion électrique peut être assurée par un conducteur intermédiaire relié électriquement à la structure en métal ferreux et au ou aux éléments. Elle peut également être directe, les éléments étant solidarisés directement avec la structure en métal ferreux, par exemple par soudure ou serrage mécanique, de manière à assurer la dite connexion électrique. _The elements can be in the form of wires, bars, blades or bars or in the form of plates. The electrical connection can be provided by an intermediate conductor electrically connected to the ferrous metal structure and to the element (s). It can also be direct, the elements being secured directly to the ferrous metal structure, for example by welding or mechanical tightening, so as to ensure said electrical connection. _
Lorsque l'élément est sous forme d'une lame, ou d'une plaquette d'épaisseur quasi constante, il présente de préférence une surépaisseur formant noyau dont la surface périphérique est inférieure au 1 /30ème de la surface superficielle de la structure, la connexion électrique étant assurée sur le dit noyau. Selon une autre caractéristique plusieurs types d'éléments sont prévus qui présentent des épaisseurs perpendiculaires à leurs surfaces superficielles, variables, le total des surfaces superficielles des éléments les plus épais étant inférieur à environ le trentième de la surface superficielle de la structure. Ces deux dernières caractéristiques ont pour objet de laisser subsister après consommation de la partie mince de l'élément qui . assure le dépôt à dominante de brucite, un élément anodique électro-négatif freinant la dissolution de la brucite et favorisant la concrétion de la masse de brucite par l'aragonite.When the element is in the form of a blade, or a plate of almost constant thickness, it preferably has an additional thickness forming a core whose peripheral surface is less than 1 / 30th of the surface surface of the structure, the electrical connection being provided on said core. According to another characteristic, several types of elements are provided which have thicknesses perpendicular to their surface surfaces, which are variable, the total of the surface surfaces of the thickest elements being less than approximately one thirtieth of the surface surface of the structure. These last two characteristics are intended to leave after consumption of the thin part of the element which. ensures the predominant deposition of brucite, an anodic electro-negative element slowing down the dissolution of brucite and favoring the concretion of the mass of brucite by aragonite.
Selon une autre caractéristique de l'invention, la structure en métal ferreux est solidarisée mécaniquement avec des matériaux électriquement inertes se trouvant sous une forme poreuse tels que du sable enfermé dans une enveloppe poreuse, des fibres naturelles ou synthétiques, des tubes ou des gaines perforés, etc.According to another characteristic of the invention, the ferrous metal structure is mechanically secured to electrically inert materials in a porous form such as sand enclosed in a porous envelope, natural or synthetic fibers, tubes or perforated sheaths , etc.
La structure en métal ferreux devant avoir une faible résistance électrique donc une section importante, section également nécessaire pour permettre le fonçage dans des fonds sableux, mais une surface au contact de l'électrolyte réduite pour avoir une forte densité de courant cathodique, il est possible de gainer la structure avec un isolant en réservant des plages à nu suivant des anneaux, des bandes ou des croisillons pour la fixation du dépôt à dominante de brucite. L'élément anodique peut être appliqué sous forme de plages à l'extérieur de la gaine avec contact électrique direct à travers l'isolant.The ferrous metal structure having to have a low electrical resistance therefore a large section, section also necessary to allow the sinking in sandy bottoms, but a reduced surface in contact with the electrolyte to have a high density of cathode current, it is possible to sheath the structure with an insulator, reserving exposed areas according to rings, bands or braces for fixing the predominantly brucite deposit. The anode element can be applied in the form of pads outside the sheath with direct electrical contact through the insulation.
Le procédé et le dispositif sont susceptibles de recevoir de nombreuses applications.The method and the device are capable of receiving numerous applications.
Une première application est la construction accélérée de récifs artificiels sous-marins, le squelette du récif étant réalisé en métal ferreux par exemple en fils ou barres de fer avec des plaquettes ou des barres de magnésium et/ou d'aluminium fixées en étant réparties dans la structure.A first application is the accelerated construction of artificial underwater reefs, the skeleton of the reef being made of ferrous metal, for example in wires or iron bars with plates or bars of magnesium and / or aluminum fixed by being distributed in the structure.
Une seconde application est la stabilisation des fonds marins tels que les fonds sableux destinés à recevoir des constructions, cette stabilisation pouvant se faire soit par fonçage dans la masse sableuse poreuse, selon un réseau, d'électrodes formant cathodes et anodes avec les interconnexions électriques ou d'élément longilignes comportant à la fois les surfaces cathodiques et les éléments anodiques, soit par formation d'une concrétion superficielle en tapis en étendant sur le fond un grillage ou treillage soudé en métal ferreux avec des éléments anodiques associés.A second application is the stabilization of the seabed such as the sandy bottom intended to receive constructions, this stabilization being able to be done either by sinking in the porous sandy mass, according to a network, of electrodes forming cathodes and anodes with the electrical interconnections or elongate element comprising both the cathode surfaces and the anode elements, either by forming a surface concretion in carpet by extending on the bottom a mesh or latticework welded in ferrous metal with associated anode elements.
Une troisième application d'un grand intérêt économique est le bouchage des fissures et le colmatage des joints dans les ouvrages marins tels que les digues immergées ou submergées, les bassins divers, etc. par insertion dans les fissures ou joints d'un élément en forme de ruban, de torsade ou analogue comportant des éléments en métal ferreux et des éléments en aluminium, zinc ou leurs alliages.A third application of great interest economical is the filling of cracks and clogging of joints in marine structures such as submerged or submerged dikes, various basins, etc. by inserting into the cracks or joints of an element in the form of a ribbon, a twist or the like comprising elements of ferrous metal and elements of aluminum, zinc or their alloys.
On peut également envisager la construction ou le renforcement par concrétion dirigée de parties immergées ou submergées d'ouvrages marins tels que ducs d'albe, pontons, etc.One can also consider the construction or reinforcement by directed concretion of submerged or submerged parts of marine structures such as dolphins, pontoons, etc.
Les applications ci-dessus ne sont données qu'à titre d'exemples illustratifs.The above applications are only given as illustrative examples.
Claims (15)
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR8401697 | 1984-02-03 | ||
| FR8401697A FR2559178B1 (en) | 1984-02-03 | 1984-02-03 | METHOD FOR ORIENTING AND ACCELERATING THE FORMATION OF CONCRETIONS IN A MARINE ENVIRONMENT AND DEVICE FOR IMPLEMENTING SAME |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0152336A1 EP0152336A1 (en) | 1985-08-21 |
| EP0152336B1 true EP0152336B1 (en) | 1988-04-20 |
Family
ID=9300750
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP85400167A Expired EP0152336B1 (en) | 1984-02-03 | 1985-02-01 | Process for directing and accelerating the formation of concretions in a marine environment and apparatus for carrying it out |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US4623433A (en) |
| EP (1) | EP0152336B1 (en) |
| CA (1) | CA1249977A (en) |
| DE (1) | DE3562279D1 (en) |
| FR (1) | FR2559178B1 (en) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3930741C1 (en) * | 1989-09-14 | 1990-12-13 | Lemfoerder Metallwaren Ag, 2844 Lemfoerde, De | |
| FR2762861B1 (en) * | 1997-04-30 | 1999-07-16 | Ifremer | METHOD FOR FORMING A NATURALLY REINFORCED CONCRETE IN AN ELECTROLYTIC MEDIUM AND THREE-DIMENSIONAL CATHODE |
| AU2065599A (en) * | 1998-01-13 | 1999-08-02 | Anthony Maxwell | Marine stock enhancement process |
| FR2862057B1 (en) * | 2003-11-07 | 2008-02-15 | Bernard Vedrenne | METHOD FOR CONTROLLING THE FORMATION OF GEO-CEMENT / NATURAL GEO-BETON |
| WO2008103675A1 (en) * | 2007-02-20 | 2008-08-28 | Brandon Nichols | Apparatus, system and method of sea water fertilization |
| CN104487458B (en) * | 2012-03-29 | 2017-09-12 | 卡勒拉公司 | Use the method and system of calcium carbide lime |
| RU2558442C1 (en) * | 2013-11-19 | 2015-08-10 | Общество с ограниченной ответственностью "Газпром добыча шельф Южно-Сахалинск" (ООО "Газпром добыча шельф Южно-Сахалинск") | Method of consolidation of soil base of hydraulic engineering structure |
| US9902652B2 (en) | 2014-04-23 | 2018-02-27 | Calera Corporation | Methods and systems for utilizing carbide lime or slag |
| FR3093735B1 (en) * | 2019-03-15 | 2023-05-19 | Geocorail | DEVICE FOR FORMING CONCRETIONS WITH REGULATED AUTONOMOUS SOURCE |
| JP2023514456A (en) | 2020-02-25 | 2023-04-05 | アレラク， インコーポレイテッド | Method and system for processing lime to form vaterite |
| CN116018195A (en) | 2020-06-30 | 2023-04-25 | 艾瑞莱克公司 | Method and system for forming vaterite from calcined limestone using an electric kiln |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB540487A (en) * | 1940-03-27 | 1941-10-20 | George Chandler Cox | Improvements relating to the protection of metallic surfaces in contact with sea water and similar liquids |
| FR1321837A (en) * | 1962-05-08 | 1963-03-22 | Thomson Houston Comp Francaise | Process for coating iron alloys |
| US4246075A (en) * | 1979-03-19 | 1981-01-20 | Marine Resources Company | Mineral accretion of large surface structures, building components and elements |
| ZA837802B (en) * | 1982-10-29 | 1985-06-26 | British Petroleum Co Plc | Method of stabilisation of particulate material |
| CA1201608A (en) * | 1982-11-22 | 1986-03-11 | Yoshiteru Sonoda | Precision pressure gauge |
-
1984
- 1984-02-03 FR FR8401697A patent/FR2559178B1/en not_active Expired
-
1985
- 1985-02-01 DE DE8585400167T patent/DE3562279D1/en not_active Expired
- 1985-02-01 EP EP85400167A patent/EP0152336B1/en not_active Expired
- 1985-02-01 CA CA000473445A patent/CA1249977A/en not_active Expired
- 1985-02-04 US US06/697,763 patent/US4623433A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| US4623433A (en) | 1986-11-18 |
| CA1249977A (en) | 1989-02-14 |
| FR2559178A1 (en) | 1985-08-09 |
| EP0152336A1 (en) | 1985-08-21 |
| DE3562279D1 (en) | 1988-05-26 |
| FR2559178B1 (en) | 1986-05-30 |
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