EP2611753A1 - Procédé pour la production de compositions de liant de ciment contenant du magnésium - Google Patents

Procédé pour la production de compositions de liant de ciment contenant du magnésium

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Publication number
EP2611753A1
EP2611753A1 EP11748633.2A EP11748633A EP2611753A1 EP 2611753 A1 EP2611753 A1 EP 2611753A1 EP 11748633 A EP11748633 A EP 11748633A EP 2611753 A1 EP2611753 A1 EP 2611753A1
Authority
EP
European Patent Office
Prior art keywords
magnesium
carbonate
magnesium oxide
range
temperature
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.)
Withdrawn
Application number
EP11748633.2A
Other languages
German (de)
English (en)
Inventor
Nikolaos Vlasopoulos
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Calix Pty Ltd
Original Assignee
Calix Pty Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority claimed from GB201014577A external-priority patent/GB201014577D0/en
Priority claimed from GBGB1014990.4A external-priority patent/GB201014990D0/en
Priority claimed from PCT/EP2011/063627 external-priority patent/WO2012028418A1/fr
Application filed by Calix Pty Ltd filed Critical Calix Pty Ltd
Priority to EP11748633.2A priority Critical patent/EP2611753A1/fr
Publication of EP2611753A1 publication Critical patent/EP2611753A1/fr
Withdrawn legal-status Critical Current

Links

Definitions

  • the present invention relates to a process for the production of cement binder compositions comprising one or more magnesium carbonates from magnesite.
  • it relates to a process for preparing certain magnesium carbonates useful as a component in a range of environmentally friendly magnesium cements which are alternatives to Portland Cement) and the like.
  • Portland cement is a well-known and ubiquitous building materia! which currently is the most common type of hydraulic cement in general use. It is manufactured on an industrial scale by heating limestone and aluminosilicates together at temperatures up to 1450°C to generate 'clinker' (various calcium silicates and a!umtnates) which is then blended with other materials e.g. gypsum (calcium sulphate) and other minor additives as required for its given duty. The manufacture of Portland cement is thus a highly energy intensive process and consequently a major source of greenhouse gas emissions.
  • magnesium based cements represent one approach to solving this problem.
  • magnesium oxychloride based cements or 'Sorei' cements, have been known since the mid-nineteenth century whilst the equivalent magnesium
  • oxysulphate materials were first developed in the 1930s. Although both are able to withstand high compressive forces, they suffer from poor water resistance making them unsuitable for external applications where significant weathering occurs.
  • US2005/103235 discloses cement compositions based on magnesium oxide containing no magnesium oxychloride or oxysulphaie. Cements made from these materials however take a relatively long time to develop their ultimate compressive strength and therefore remain capable of further improvement.
  • a process for producing a cement binder composition comprising one or more magnesium carbonates having the general formula w MgC0 3 . x MgO . y g(OH) 2 - z H 2 0 in which w is a number equal to or greater than 1 , at least one of x, y and z is a number greater than 0 and w, x, y and z may be (but need not be) integers characterised in that the process comprises the steps of (a) heating magnesite to liberate carbon dioxide gas and produce a solid product comprising magnesium oxide, (b) contacting an aqueous mixture comprising the magnesium oxide produced in step (a) with a source of carbonate ions at a temperature in the range 25 to 120°C to produce at least one of the magnesium carbonates, (c) optionally heating the magnesium carbonate product(s) of step (b) at a temperature from 45 to 500°C and (d) blending the magnesium carbonate(s) produced in
  • the magnesite used in the process disclosed herein can be derived from any source and the use of both or either of naturally occurring magnesite ore and synthetically generated magnesite is contemplated.
  • Typical sources of synthetically produced magnesite include those materials produced by the carbonation of magnesium-containing silicate ores (especially olivine, serpentine or talc), those produced by treating sea water with carbon dioxide gas in the presence of an inorganic base (e.g. a Group IA metal hydroxide such as sodium hydroxide) and those obtained by reacting magnesium hydroxide or magnesium oxide with carbon dioxide.
  • an inorganic base e.g. a Group IA metal hydroxide such as sodium hydroxide
  • impurities e.g.
  • oxides of sulphur and nitrogen can be tolerated it is preferred that it is relatively pure and certainly free from noxious hydrogen sulphide or mercaptans so that the magnesite produced is as pure as possible.
  • Sources of impure carbon dioxide e.g. flue gases and the like should therefore be purified before use.
  • the magnesium carbonates produced in the process of the present invention are magnesium carbonates having the general formula w gC0 3 . x MgO . y g(OH) 2 . z H 2 0 in which w is a number equal to or greater than 1 , at least one of x, y and z is a number greater than 0, and w, x, y and z may be (but need not be) integers. Included in this definition are, for example, synthetic products corresponding stoichiometrically to the following naturally occurring hydrated magnesium carbonates: barringtonite
  • the magnesium carbonates produced are those having the general formula gCO 3 .wH 2 0 wherein w is a number in the range 0.5 to 5, preferably 0.8 to 2.7.
  • step (a) of the process magnesite feedstock is heated in a kiln or caiciner to a temperature in the range 500 to 1400°C, preferably in the range of 500 to 1000°C, most preferably in the range of 550 to 800°C and typically at a pressure of up to 1 MPa.
  • step (a) may be carried out batchwise or continuously.
  • step (b) of the process the magnesium oxide produced in step (a) is contacted with a source of carbonate ions in an aqueous medium.
  • Such carbonate ions can be added directly, for example by directly introducing a solid carbonate or bicarbonate salt (e.g. a sodium or potassium carbonate or bicarbonate) into the aqueous medium, or indirectly by contacting the mixture with carbon dioxide in which case carbonate ions are generated in situ. It is also possible to use both sources.
  • Step (b) is suitably carried out at a temperature in the range 25 to 120°C, preferably in the range 25 to 65°C if the object is to make a nesquehonite type material and 65 to 120°C if the object is to make a hydromagnesite type material.
  • step (b) involves the use of carbon dioxide
  • the partial pressure is preferably up to 1MPa, more preferably from 0.1 to 1 MPa and most preferably from 0.1 to 0.5MPa.
  • steps (a) and (b) are carried out at one and the same carbon dioxide partial pressure within the typical constraints of industrial process technology.
  • carbonate or bicarbonate salts are used as the source of carbonate ion it is preferred that the molar ratio of magnesium oxide to carbonate ions in step (b) is in the range 1 :10 to 10:1 more preferably 1:5 to 5:1 most preferably 1 :3 to 3:1.
  • step (b) may comprise only partial carbonation, for example by using less carbonate ton relative to the magnesium oxide (in molar terms) or, where carbon dioxide gas is employed, by working at lower temperature and pressures and for shorter residence times.
  • step (b) may comprise only partial carbonation, for example by using less carbonate ton relative to the magnesium oxide (in molar terms) or, where carbon dioxide gas is employed, by working at lower temperature and pressures and for shorter residence times.
  • the solid magnesium carbonate(s) produced can be separated from the aqueous medium using known methods e.g. filtration or the use of a hydrocyclone. The product so obtained may be washed to remove any residual metal salts at this stage if so desired.
  • magnesium carbonate(s) produced in step (b) can be heated in step
  • Step (d) of the process disclosed herein comprises blending the magnesium carbonate(s) produced in step (b) or optional step (c) with at least magnesium oxide to produce a cement binder composition.
  • a third component selected from one or more of the group consisting of silica, alumina, silicates, aluminates aluminosilicates, magnesite, magnesium hydroxide and pozzolans having a non-specific chemical composition is blended along with the magnesium carbonate and magnesium oxide.
  • the cement binder compositions produced by blending these three components together comprise (a) 30-80% by weight of the magnesium carbonates described above and magnesium oxide in total and (b) 20-70% by weight of the third component.
  • the cement binder composition comprises 20- 60% by weight of the third component, more preferably 25-45% and most preferably 25- 40%.
  • Exemplary preferred cement binder compositions are also those which contain 40- 60%) by weight of the magnesium carbonate(s) and magnesium oxide in total and 40 to 60% of the third component most preferably 45-55% in total of the former and 45 to 55% of the latter.
  • the relative proportions of the magnesium carbonate(s) and magnesium oxide in our cement binder compositions will depend to a certain extent on the amount of third component employed and the degree of crystallinity of the magnesium carbonate used. With this in mind it has been found that the following broad compositional ranges (% by weight of their total) produce useful cement binders: (a) 5-90% of the magnesium carbonate(s) and (b) 10-95% of magnesium oxide. Within this broad envelope the following six typical composition ranges are preferred:
  • the third component preferably comprises one or more of quartz, cristobalite, fumed silicas, corundum, beta- and gamma- alumina, aluminosilicates such as clays, zeolites, spent catalytic cracking catalysts, metal silicates including but not limited to Group IA and IIA metal silicates e.g. sodium silicate.
  • the third component may also comprise pozzolans having a variable and therefore non-specific physical or chemical composition e.g. slag, glass waste, f!y ash and the like.
  • the third component may comprise one or more of magnesite, magnesium hydroxide or magnesium silicate (e.g. olivine or serpentine).
  • step (d) is carried out by continuous or batch-wise mixing of the
  • the final formulated cement binder so produced can then be stored under dry conditions and/or bagged ready for sale to wholesale or end-users. It is especially useful in the manufacture of concretes, mortars and grouts for the building industry.
  • the magnesium carbonate(s) produced by the process of the present invention, along with magnesium oxide, can also be used as additives to Portland cement to improve the latter's carbon footprint per unit tonne of material sold. If this approach is adopted then it is preferred that the Portland cement comprises no more than 50%, preferably less than 25% by weight of the total of the magnesium oxide and the magnesium carbonate(s).
  • the cement binder compositions comprise magnesium carbonate(s) and magnesium oxide which are both derived from magnesite, preferably a common source of magnesite thereby allowing the cement binder composition to be produced in a single integrated scheme.
  • Naturally occurring magnesite ore having an average particle size of 250 microns is pre-heated before being introduced into the top of a rotary kiln operating at 700°C and 0.2MPa where it is allowed to flow downwards under the influence of gravity to an exit pipe at the bottom where magnesium oxide is withdrawn either continuously or periodically.
  • carbon dioxide gas is continuously removed overhead from the kiln. The carbon dioxide so recovered is then cooled against the incoming magnesite feed to the kiln, by means of a series of shell and tube heat exchangers to a temperature of 45°C.
  • the magnesium oxide recovered from the bottom of the kiln is likewise cooled down to 45°C for example by cooling against cold water thereby raising steam which can be used elsewhere in the process for heating and power. 20% by weight of the magnesium oxide so produced is then dispersed as a 5% by weight suspension in water before being fed to a stainless-steel stirred pressure vessel where it is contacted with the cooled carbon dioxide gas recovered from the kiln at a temperature of 45°C and 0.2 Pa.
  • the residence time of the magnesium oxide feed in the reactor is five hours. The solids removed from the reactor at the end of this period are shown by X-ray powder diffraction to be nesquehonite.
  • a mixture of 96g of MgO (surface area of 30m 2 /g), 24g of nesquehonite and 80g of glass waste powder was added to 94g of water and mixed for 5 minutes.
  • the resulting mixture was cast into 10x10x60 steel moulds and cured in water.
  • the samples achieved a compressive strength of 27 MPa after 28 days.

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  • Curing Cements, Concrete, And Artificial Stone (AREA)

Abstract

L'invention décrit un procédé pour la production d'une composition de liant de ciment comprenant un ou plusieurs carbonates de magnésium présentant la formule générale w MgCO3. x MgO. y Mg(OH)2.z H2O dans laquelle w représente un nombre égal ou supérieur à 1, au moins l'un parmi x, y et z représente un nombre supérieur à 0 et w, x, y et z peuvent être (mais ne doivent pas être) des entiers. Le procédé est caractérisé par les étapes de (a) chauffage de la magnésite pour libérer du dioxyde de carbone gazeux et pour produire un produit solide comprenant de l'oxyde de magnésium et (b) mise en contact d'un mélange aqueux comprenant l'oxyde de magnésium produit dans l'étape (a) avec une source d'ions carbonate à une température dans la plage de 25 à 120°C pour produire au moins un des carbonates de magnésium, (c) éventuellement chauffage du/des produit(s) de carbonate(s) de magnésium de l'étape (b) à une température de 45 à 500°C et (d) mélange du/des carbonate(s) de magnésium produit(s) dans l'étape (b) ou l'étape éventuelle (c) avec au moins un oxyde de magnésium pour produire une composition de liant de ciment. Le procédé est approprié pour le traitement soit de la magnésite naturelle soit de la magnésite produite d'une autre manière, la carbonatation minérale du silicate de magnésium, la carbonatation de l'hydroxyde de magnésium ou le traitement de l'eau de mer avec du dioxyde de carbone en présence d'une base inorganique.
EP11748633.2A 2010-09-02 2011-08-18 Procédé pour la production de compositions de liant de ciment contenant du magnésium Withdrawn EP2611753A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP11748633.2A EP2611753A1 (fr) 2010-09-02 2011-08-18 Procédé pour la production de compositions de liant de ciment contenant du magnésium

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
GB201014577A GB201014577D0 (en) 2010-09-02 2010-09-02 Binder composition
GBGB1014990.4A GB201014990D0 (en) 2010-09-09 2010-09-09 Integrated process for producing compositions containing magnesium
PCT/EP2011/063627 WO2012028418A1 (fr) 2010-09-02 2011-08-08 Procédé intégré pour la production de compositions contenant du magnésium
PCT/EP2011/063629 WO2012028419A1 (fr) 2010-09-02 2011-08-08 Composition de liant
PCT/EP2011/064248 WO2012028471A1 (fr) 2010-09-02 2011-08-18 Procédé pour la production de compositions de liant de ciment contenant du magnésium
EP11748633.2A EP2611753A1 (fr) 2010-09-02 2011-08-18 Procédé pour la production de compositions de liant de ciment contenant du magnésium

Publications (1)

Publication Number Publication Date
EP2611753A1 true EP2611753A1 (fr) 2013-07-10

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP11748633.2A Withdrawn EP2611753A1 (fr) 2010-09-02 2011-08-18 Procédé pour la production de compositions de liant de ciment contenant du magnésium

Country Status (1)

Country Link
EP (1) EP2611753A1 (fr)

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2012028471A1 *

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