AU2018222897A1 - Method for production of hydromagnesite - Google Patents
Method for production of hydromagnesite Download PDFInfo
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- AU2018222897A1 AU2018222897A1 AU2018222897A AU2018222897A AU2018222897A1 AU 2018222897 A1 AU2018222897 A1 AU 2018222897A1 AU 2018222897 A AU2018222897 A AU 2018222897A AU 2018222897 A AU2018222897 A AU 2018222897A AU 2018222897 A1 AU2018222897 A1 AU 2018222897A1
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- Australia
- Prior art keywords
- water
- hydromagnesite
- hydroxide
- source
- brucite
- Prior art date
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- Abandoned
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- ZLNQQNXFFQJAID-UHFFFAOYSA-L magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 title claims abstract description 86
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 14
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 90
- 238000000034 method Methods 0.000 claims abstract description 71
- 229910052599 brucite Inorganic materials 0.000 claims abstract description 51
- 239000011777 magnesium Substances 0.000 claims abstract description 48
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims abstract description 44
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 claims abstract description 43
- 229910001425 magnesium ion Inorganic materials 0.000 claims abstract description 35
- 230000001143 conditioned effect Effects 0.000 claims abstract description 34
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 claims abstract description 29
- 239000007787 solid Substances 0.000 claims abstract description 24
- 229910001862 magnesium hydroxide Inorganic materials 0.000 claims abstract description 20
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 claims abstract description 19
- 239000000347 magnesium hydroxide Substances 0.000 claims abstract description 19
- 235000012254 magnesium hydroxide Nutrition 0.000 claims abstract description 14
- 238000011084 recovery Methods 0.000 claims abstract description 14
- 230000003750 conditioning effect Effects 0.000 claims abstract description 9
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 8
- 239000012267 brine Substances 0.000 claims description 58
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 claims description 58
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims description 30
- 229910052749 magnesium Inorganic materials 0.000 claims description 30
- 239000000243 solution Substances 0.000 claims description 30
- 239000003245 coal Substances 0.000 claims description 29
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 27
- 150000003839 salts Chemical class 0.000 claims description 14
- 230000008569 process Effects 0.000 claims description 13
- 238000001223 reverse osmosis Methods 0.000 claims description 13
- 150000004820 halides Chemical class 0.000 claims description 12
- -1 NaCI Chemical class 0.000 claims description 8
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 8
- 238000010923 batch production Methods 0.000 claims description 7
- 238000001914 filtration Methods 0.000 claims description 6
- 238000001035 drying Methods 0.000 claims description 5
- 238000005201 scrubbing Methods 0.000 claims description 5
- 238000005406 washing Methods 0.000 claims description 5
- CPELXLSAUQHCOX-UHFFFAOYSA-M Bromide Chemical compound [Br-] CPELXLSAUQHCOX-UHFFFAOYSA-M 0.000 claims description 4
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 claims description 4
- XMBWDFGMSWQBCA-UHFFFAOYSA-N hydrogen iodide Chemical compound I XMBWDFGMSWQBCA-UHFFFAOYSA-N 0.000 claims description 4
- 230000003647 oxidation Effects 0.000 claims description 4
- 238000007254 oxidation reaction Methods 0.000 claims description 4
- 230000020477 pH reduction Effects 0.000 claims description 4
- 239000000377 silicon dioxide Substances 0.000 claims description 4
- 230000000779 depleting effect Effects 0.000 claims description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 59
- 229910002092 carbon dioxide Inorganic materials 0.000 description 33
- 229940091250 magnesium supplement Drugs 0.000 description 28
- BVKZGUZCCUSVTD-UHFFFAOYSA-M Bicarbonate Chemical compound OC([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-M 0.000 description 23
- 239000001569 carbon dioxide Substances 0.000 description 20
- 239000007789 gas Substances 0.000 description 18
- 238000006243 chemical reaction Methods 0.000 description 15
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 14
- 239000011575 calcium Substances 0.000 description 14
- 229910000021 magnesium carbonate Inorganic materials 0.000 description 14
- 238000011282 treatment Methods 0.000 description 14
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 12
- 229910052791 calcium Inorganic materials 0.000 description 12
- 239000001095 magnesium carbonate Substances 0.000 description 12
- 239000008398 formation water Substances 0.000 description 9
- 241000894007 species Species 0.000 description 9
- 239000002699 waste material Substances 0.000 description 9
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L Magnesium chloride Chemical compound [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 description 8
- 235000014380 magnesium carbonate Nutrition 0.000 description 8
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 8
- 239000000047 product Substances 0.000 description 8
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 description 6
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 6
- 229910000019 calcium carbonate Inorganic materials 0.000 description 6
- 235000010216 calcium carbonate Nutrition 0.000 description 6
- 239000000395 magnesium oxide Substances 0.000 description 6
- 238000012545 processing Methods 0.000 description 6
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical class [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 5
- 239000002253 acid Substances 0.000 description 5
- 239000003518 caustics Substances 0.000 description 5
- 229910000022 magnesium bicarbonate Inorganic materials 0.000 description 5
- 238000002203 pretreatment Methods 0.000 description 5
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 4
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 4
- 238000001704 evaporation Methods 0.000 description 4
- 230000008020 evaporation Effects 0.000 description 4
- 229910052500 inorganic mineral Inorganic materials 0.000 description 4
- 230000000670 limiting effect Effects 0.000 description 4
- 229960002337 magnesium chloride Drugs 0.000 description 4
- 229910001629 magnesium chloride Inorganic materials 0.000 description 4
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 4
- 235000010755 mineral Nutrition 0.000 description 4
- 239000011707 mineral Substances 0.000 description 4
- 239000011780 sodium chloride Substances 0.000 description 4
- 150000001450 anions Chemical class 0.000 description 3
- 239000008364 bulk solution Substances 0.000 description 3
- 239000000920 calcium hydroxide Substances 0.000 description 3
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 3
- 150000001768 cations Chemical class 0.000 description 3
- 239000000470 constituent Substances 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 238000002425 crystallisation Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 239000012530 fluid Substances 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 230000036961 partial effect Effects 0.000 description 3
- 238000001556 precipitation Methods 0.000 description 3
- 239000011734 sodium Substances 0.000 description 3
- 229910052708 sodium Inorganic materials 0.000 description 3
- 235000017557 sodium bicarbonate Nutrition 0.000 description 3
- 229910000030 sodium bicarbonate Inorganic materials 0.000 description 3
- 159000000000 sodium salts Chemical class 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 2
- CSNNHWWHGAXBCP-UHFFFAOYSA-L Magnesium sulfate Chemical compound [Mg+2].[O-][S+2]([O-])([O-])[O-] CSNNHWWHGAXBCP-UHFFFAOYSA-L 0.000 description 2
- 229910052794 bromium Inorganic materials 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 229910000514 dolomite Inorganic materials 0.000 description 2
- 238000005187 foaming Methods 0.000 description 2
- QWDJLDTYWNBUKE-UHFFFAOYSA-L magnesium bicarbonate Chemical compound [Mg+2].OC([O-])=O.OC([O-])=O QWDJLDTYWNBUKE-UHFFFAOYSA-L 0.000 description 2
- 239000002370 magnesium bicarbonate Substances 0.000 description 2
- 235000014824 magnesium bicarbonate Nutrition 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 239000012466 permeate Substances 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 229940088417 precipitated calcium carbonate Drugs 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 239000013535 sea water Substances 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 229910000029 sodium carbonate Inorganic materials 0.000 description 2
- 241000272875 Ardeidae Species 0.000 description 1
- WKBOTKDWSSQWDR-UHFFFAOYSA-N Bromine atom Chemical compound [Br] WKBOTKDWSSQWDR-UHFFFAOYSA-N 0.000 description 1
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 1
- 239000004606 Fillers/Extenders Substances 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 235000011941 Tilia x europaea Nutrition 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- GDTBXPJZTBHREO-UHFFFAOYSA-N bromine Substances BrBr GDTBXPJZTBHREO-UHFFFAOYSA-N 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-N carbonic acid Chemical compound OC(O)=O BVKZGUZCCUSVTD-UHFFFAOYSA-N 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000010612 desalination reaction Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 150000004683 dihydrates Chemical class 0.000 description 1
- 238000009300 dissolved air flotation Methods 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 239000010459 dolomite Substances 0.000 description 1
- 238000000909 electrodialysis Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000007717 exclusion Effects 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 239000003063 flame retardant Substances 0.000 description 1
- 239000005431 greenhouse gas Substances 0.000 description 1
- UOVKYUCEFPSRIJ-UHFFFAOYSA-D hexamagnesium;tetracarbonate;dihydroxide;pentahydrate Chemical compound O.O.O.O.O.[OH-].[OH-].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[O-]C([O-])=O.[O-]C([O-])=O.[O-]C([O-])=O.[O-]C([O-])=O UOVKYUCEFPSRIJ-UHFFFAOYSA-D 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 150000004679 hydroxides Chemical class 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000011221 initial treatment Methods 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 238000012432 intermediate storage Methods 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 238000003973 irrigation Methods 0.000 description 1
- 230000002262 irrigation Effects 0.000 description 1
- 239000004571 lime Substances 0.000 description 1
- 244000144972 livestock Species 0.000 description 1
- 229940050906 magnesium chloride hexahydrate Drugs 0.000 description 1
- DHRRIBDTHFBPNG-UHFFFAOYSA-L magnesium dichloride hexahydrate Chemical compound O.O.O.O.O.O.[Mg+2].[Cl-].[Cl-] DHRRIBDTHFBPNG-UHFFFAOYSA-L 0.000 description 1
- YIXJRHPUWRPCBB-UHFFFAOYSA-N magnesium nitrate Inorganic materials [Mg+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O YIXJRHPUWRPCBB-UHFFFAOYSA-N 0.000 description 1
- 159000000003 magnesium salts Chemical class 0.000 description 1
- 229910052943 magnesium sulfate Inorganic materials 0.000 description 1
- 235000019341 magnesium sulphate Nutrition 0.000 description 1
- ZEYIGTRJOAQUPJ-UHFFFAOYSA-L magnesium;carbonate;dihydrate Chemical compound O.O.[Mg+2].[O-]C([O-])=O ZEYIGTRJOAQUPJ-UHFFFAOYSA-L 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- VUZPPFZMUPKLLV-UHFFFAOYSA-N methane;hydrate Chemical compound C.O VUZPPFZMUPKLLV-UHFFFAOYSA-N 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 150000004686 pentahydrates Chemical class 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000002829 reductive effect Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- XZPVPNZTYPUODG-UHFFFAOYSA-M sodium;chloride;dihydrate Chemical compound O.O.[Na+].[Cl-] XZPVPNZTYPUODG-UHFFFAOYSA-M 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000008719 thickening Effects 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 238000004448 titration Methods 0.000 description 1
- 150000004684 trihydrates Chemical class 0.000 description 1
- 238000001291 vacuum drying Methods 0.000 description 1
- 238000004065 wastewater treatment Methods 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W10/00—Technologies for wastewater treatment
- Y02W10/30—Wastewater or sewage treatment systems using renewable energies
- Y02W10/37—Wastewater or sewage treatment systems using renewable energies using solar energy
Landscapes
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
- Removal Of Specific Substances (AREA)
Abstract
A method for the production of hydromagnesite comprising: conditioning water having carbonate alkalinity with a source of hydroxide; adding a source of magnesium ions to the conditioned water, thereby forming an ultrafine brucite 5 (Mg(OH)2) solid in the conditioned water; continuing addition of the source of magnesium ions, thereby resolubilising the ultrafine brucite and forming hydromagnesite; and recovering the hydromagnesite. - 200 H20with carbonate alkalinity - 210 Source of - 220 Conditioned - 230 Source of Mg 2+ - 240 Ultrafine brucite formation - 250 Resolubilise brucite & form HMag - 260 Recovery of HMag
Description
METHOD FOR PRODUCTION OF HYDROMAGNESITE
FIELD OF INVENTION
The present invention relates to methods for the production of hydromagnesite, specifically the recovery of hydromagnesite from water having carbonate/bicarbonate alkalinity, and optionally salinity (i.e. sodium salts of chloride), such as, but not limited to, coal seam brine.
BACKGROUND ART
Carbonate Alkalinity
Carbonate alkalinity in water has traditionally been dealt with through treatments using acid. In the case of coal seam gas, carbonate alkalinity which includes both carbonate and bicarbonate is high enough to make the addition of acid a costly exercise. The evolution of carbon dioxide gas during this process is an undesirable consequence of existing treatment schemes, since it is a greenhouse gas and also because it causes significant processing issues.
In common water treatment schemes, conventional thinking has been to adjust alkalinity with acid and not caustic. Addition of magnesium generates magnesium carbonate (MgCO3) with no addition of caustic. Generally, precipitants generate another waste stream that must be dealt with and this is not desirable. Furthermore, it is generally not possible to produce commercial products from such waste streams.
The coal seam gas industry has spent significant resources and several years investigating how to process brines into commercial, saleable products, primarily
2018222897 28 Aug 2018 looking at separating sodium salts of chloride and bicarbonate and carbonate. This approach was taken up by the industry and subsequently abandoned due to massive capital investment requirements and expensive ongoing operating costs.
Alkalinity and pH in the above systems have a relationship. Generally, above a pH of 10.2, constituents are hydroxide ion and carbonate ion; between a pH of 10.2 and 8.3, constituents are carbonate and bicarbonate; between a pH of 8.3 and 4.3, constituents are bicarbonate and carbon dioxide; and below 4.3 free acidity and carbon dioxide are present. Other species present in the water and io operating conditions may distort this. Graphically:
| OH- | COs2’ | |
| 10.2 | ||
| COs2’ | HCO3- | |
| 8.3 | ||
| HCO3- | CO2 | |
| 4.3 | ||
| CO2 | Acid |
Table 1: Alkalinity and pH
Magnesium Carbonate
Magnesium carbonate, MgCO3, is a white solid that occurs in nature as a mineral. Several hydrated and basic forms of magnesium carbonate also exist as minerals. In addition, MgCO3 has a variety of applications. The most common magnesium carbonate forms are the anhydrous salt called magnesite (MgCOs) and the di, tri, and pentahydrates known as barringtonite (MgCO3-2H2O),
2018222897 28 Aug 2018 nesquehonite (MgCO3-3H2O), and lansfordite (MgCO3-5H2O), respectively. Some basic forms such as artinite (MgCO3-Mg(OH)2-3H2O), hydromagnestite (4MgCO3-Mg(OH)2-4H2O), and dypingite (4MgCC>3· Mg(OH)2-5H2O) also occur as minerals.
Magnesium carbonate can be prepared in laboratory by reaction between any soluble magnesium salt and sodium bicarbonate:
MgCI2(aq) + 2NaHCO3(aq) -+ MgCO3(s) + 2NaCI(aq) + H2O(I) + CO2(g)
When the solution of magnesium chloride (or sulfate) is treated with aqueous sodium carbonate, a precipitate of basic magnesium carbonate is formed:
5MgCI2(aq) + 5Na2CO3(aq) + 5H2O(I) -+ Mg(OH)2-3MgCO3-3H2O(s) + Mg(HCO3)2(aq) + 10NaCI(aq)
High purity industrial routes include a path through magnesium bicarbonate: combining magnesium hydroxide and carbon dioxide. A slurry of magnesium hydroxide is treated with 3.5 to 5 atm of carbon dioxide below 50°C, giving the soluble bicarbonate, then vacuum drying the filtrate, which returns half of the carbon dioxide as well as water:
Mg(OH)2 + 2 CO2 Mg(HCO3)2
Mg(HCO3)2 -+ MgCOs + CO2 + H2O
Water Treatment
Brackish water is often produced as a by-product of coal seam gas extraction/exploitation in Queensland, Australia. This water is of no practical use as the salinity is too high for irrigation and not fit for livestock watering purposes.
2018222897 28 Aug 2018
At the volumes produced, this water poses an environmental threat to agricultural and native land and water courses due to the salinity of the water. Thus, the water is confined to being collected and treated. Additionally, coal seam gas operators are increasingly confined to a zero liquid discharge (ZLD) requirement, and so treating the formation water for beneficial use is compulsory. It is noted that ZLD means that, eventually, solids must be produced and disposed of. It means that the only streams ‘discharged’ are essentially ‘dry’ solids. Dry may also mean, for example, an 85 wt% slurry going to landfill.
The treatment of this water generates a significant reject or waste stream that has no useful end point. It is noted that ‘reject’ is generally a technical term defining a part of processed brine. ‘RO reject’ is also used to describe this stream. Moreover, government regulations dictate that the salt or waste stream must be treated to create useable products wherever feasible. In the case of no commercial solution, the brine must be further processed until the dissolved salts are made solid. These ‘solids’ generally have to be disposed of in a regulated waste facility.
Water produced from each well is collected in a water gathering system. The water gathering system connects all of the individual wells to a central conduit, which delivers all of the collected water to a water treatment facility.
The treatment of coal seam gas produced water is primarily focussed on recovering useable water which can be distributed to end users, such as agriculture industries and nearby communities. This reduction in volume is also desirable to the CSG operators since it is cheaper than storing the sheer volume produced in engineered dams.
2018222897 28 Aug 2018
Before the water is treated, it usually undergoes pre-treatment, which prepares the water for the treatment processes. Typical pre-treatment processes which may be employed include filtration, dissolved air flotation, ion exchange, chemical addition, and electrodialysis.
Reverse osmosis (RO) is the primary treatment process used to treat and purify CSG water. Subsequent processing may be employed, including distillation and solar evaporation. In the case of RO, the formation water is divided into a permeate stream and a reject stream. The reject stream, also known as RO reject, is generally more concentrated in dissolved solids than the formation water feedstock. Reverse osmosis plants are run at high permeate recoveries, since the object is to reduce volume of the feed water so that the problem becomes more manageable. This generates a significant volume of useable, high quality water, which is easy to offload for the operator. It also generates a lesser, but problematic volume of unusable brine.
The reject stream, or RO reject, can be further reduced in volume by brine concentrators which are able to generate a distillate stream of water and a concentrated liquor stream of high temperature and high salinity, referred to as CSG brine.
Coal seam gas brine, which may generally be described as a brine having >40,000 mg/l TDS, is further treated by evaporation, thermal or mechanical separation, desalination processes or the like. The initial aim is to reduce the volume of the coal seam brine so that it is manageable. The ultimate aim is to reduce the brine to crystalline solids and then dispose of those solids according to enviro-legal obligations. This is also the subject of significant cost issues.
2018222897 28 Aug 2018
Currently operating brine concentrators use mechanical vapour recompression to operate, which means that they effectively operate at (near) atmospheric pressures.
Attempts have been made to commercially recover minerals from coal seam brine or formation water, but these have met with little, if any, success. Evaporation of the RO reject stream (i.e. CSG brine), which may have been exposed to the environment in intermediate storage ponds/dams, ultimately results in a waste mixed salt that is fated for disposal in a regulated waste facility. A large cost is usually associated with the disposal of the waste salt since it requires the construction of an engineered salt storage facility and transportation to the waste salt facility (i.e. if it is not collocated within the evaporation facility).
The method of the invention generally relies heavily on an understanding of the carbonate system in the formation water as it is processed, as well as crystallisation phenomena and aqueous chemistry. As such, these issues will be discussed briefly below.
The carbonate system involves equilibrium of carbon dioxide speciation in water. The species present and the proportioning between species are dependent on the pH of the solution, as discussed above.
Carbonate equilibria may be represented by the following equations:
CO2 fgy + Liquid Water + Pressure # CO2 (eg) + Ηζθ [HzCOalicq) [Η2^031:ος)^[Η+]ος + [Ηυθ3-](ος) 2[HCO3-](q?) # [H2CO3](Q(?) + [CO32-] (Q?) [HCO3-](Q(j)^[H*]Q(J+[CO3 z-]CQg)
2018222897 28 Aug 2018 [H+]Qg+[OH-](Qg)#H2O([)
Ultimately, carbon dioxide equilibria in aqueous environments is dictated by the partial pressure of CO2 gas, and the presence of hydroxide in the liquid.
CSG formation water (in coal seam/subterranean aquifers) is composed of predominantly sodium bicarbonate and sodium chloride in solution. As soon as the formation water leaves in the aquifer, carbon dioxide starts evolving from solution. The reason for this is that the partial pressure of carbon dioxide outside the aquifer is less than the pressure in the aquifer.
Some carbon dioxide also comes out of solution as the formation water is progressively treated. An observable effect of this is that the pH of solution generally increases as the formation water is progressively treated. The pH at equilibrium in the aquifer may be as low as 7.1. However, by the time it is rejected by RO, the pH may be around 9. If the brine is then evaporated, more CO2 will evolve. Concentrated brine may have a pH closer to 10.
Hydromagnesite
Hydromagnesite in its high quality form is a precipitated hydrated basic magnesium carbonate with the formula Mgs(CO3)4(OH)2.4H2O which has many valuable uses, such as titanium extender, replacement for precipitated calcium carbonate, fire retardants, etc.
There are several routes for production of hydromagnesite. One example is the bicarbonate route:
5MgCl2(flq? + 10NaHCO3(Qlj) — Mg5(C03)4(0H)2.4H2013) + 6CO2(j) + 10NaCl(Qq)
2018222897 28 Aug 2018
The bicarbonate route involves a reaction of sodium bicarbonate and magnesium chloride at elevated temperature. In this process, 60% of the moles of bicarbonate evolve as CO2 gas. This may create operational problems (from associated foaming), and the reaction time is excessive, since CO2 takes a long time to completely evolve from solution. The reaction forms magnesium bicarbonate, Mg(HCC>3)2, as an intermediate species, which is unstable and has to lose a carbon dioxide molecule so that it can participate in the formation of hydromagnesite chains. Endpoint control may not be possible or practical and, because of this, further concentration of the effluent is difficult. This is because carbon dioxide foaming remains a real issue. Additionally, a blunt end point leaves either an excess of remaining bicarbonate/carbonate alkalinity, or an excess of magnesium ions in solution which impacts on the subsequent recovery of a useable sodium chloride product from the effluent.
For reference only, Figure 1 illustrates a chart that examines the solution chemistry of the bicarbonate route. For the bicarbonate route, there is a lack of convergence of species at the end point of the reaction (0.5 moles MgCk). There is still carbon in solution, but there is also magnesium remaining in solution. Carbon dioxide gas is also generated throughout the reaction.
Salt Recovery
Crystallisation is a purification technique. The main factor determining the recovery of crystal from a liquor within specification is the composition of the starting liquor. In terms of NaCl crystallisation, the ratios of sodium to other cations and chloride to other anions are of critical importance. Of some concern during the development of the present invention were the ratios of CI:Br, Cl:I and Na:Mg.
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The first crystals produced by a liquor are the purest. As NaCI crystallises, the liquor becomes more concentrated with impurities, such as bromine and magnesium. This means that the critical ratios are adversely changing as the brine is processed. Since the ratios in the starting solution determine the possible salt recoverable before a specification is exceeded, altering the ratios allows significantly more salt to be recovered.
The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate exemplary technology areas where some embodiments described herein may be practiced.
Various aspects and embodiments of the invention will now be described.
SUMMARY OF INVENTION
As mentioned above, the present invention relates generally to methods for the production of hydromagnesite, specifically the recovery of hydromagnesite from water having carbonate/bicarbonate alkalinity, and optionally salinity (i.e. sodium salts of chloride), such as, but not limited to, coal seam brine.
According to one aspect of the invention there is provided a method for the production of hydromagnesite comprising:
conditioning water having carbonate alkalinity with a source of hydroxide;
adding a source of magnesium ions to the conditioned water, thereby forming an ultrafine brucite (Mg(OH)2) solid in the conditioned water and depleting hydroxide in the conditioned water;
continuing addition of the source of magnesium ions, thereby resolubilising the ultrafine brucite and forming hydromagnesite; and
2018222897 28 Aug 2018 recovering the hydromagnesite.
As used herein, the term “ultrafine brucite” refers to a brucite (Mg(OH)2) solid that is dispersed in the solution, e.g. the conditioned brine. The ultrafine brucite 5 presents as a gelatinous mass in the solution. While not wishing to be bound, it is thought that the brucite particles have a particle size of less than 1 pm.
In a preferred embodiment, the conditioned water has a carbonate:hydroxide ratio of at least 2:1, preferably approximately 2:1.
io
The source of hydroxide is preferably NaOH. The source of hydroxide may be an aqueous source of hydroxide, or may be some other form. The source of magnesium ions is preferably MgCh, though Mg(NO3)2 or MgSO4 may also be used. The latter options may introduce economic and processing disadvantages 15 compared with MgCL The source of magnesium ion may be an aqueous source of magnesium ion, or may be some other form.
The temperature of the conditioned water is preferably above about 55°C. In preferred embodiments, the temperature is maintained throughout the method or 20 treatment.
As will be appreciated from the above discussion, in one particular embodiment the water having carbonate alkalinity is coal seam gas brine. For example, the coal seam gas brine may have a dissolved solids content of up to up to 25 saturation point, for example up to about 30 wt%. It will generally be preferred that the coal seam gas brine be pre-treated prior to conditioning with the source of hydroxide, such as with filtration of organics, scrubbing, concentration and/or reverse osmosis. In most cases, the coal seam brine is preferably pre-treated to remove unwanted components, such as silica and/or fluoride.
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In certain embodiments, the methods of the invention further comprise removing contaminating halides following formation of the hydromagnesite. The removed contaminated halides may comprise bromide and iodide, the removal preferably comprising acidification of water containing the halides, followed by oxidation.
Additional value may be realised through the recovery of other compounds using the methods of the invention. For example, in certain embodiments the methods further comprise recovering remanent salt, such as NaCI, following removal of the hydromagnesite.
Recovery of the hydromagnesite may comprise dewatering, washing and drying.
It should further be appreciated that the methods described above may be batch or semi-batch processes or may be continuous. It is envisaged that the methods of the invention will preferably be continuous, particularly in the cases where the water feed for processing is voluminous, such as in the case of waste water treatment (e.g. coal seam gas brine treatment). Batch or semi-batch processing may be advantageous if there is a need to account for variations in the feed stock.
The method may comprise maintaining pH and/or Mg ion in the conditioned water by adjusting addition of the source of hydroxide, if needed, to achieve the predetermined carbonate equilibria in the conditioned water. For example, the pH may be monitored to ensure it remains at or above 8.3 to suppress any CO2 generation. Mg ion content may be monitored as a rise in Mg ion may be accompanied by CO2 generation from the system.
According to another aspect of the invention there is provided a method for the production of hydromagnesite comprising:
2018222897 28 Aug 2018 providing water having carbonate alkalinity;
adding an ultrafine brucite solid to the water to condition the water;
adding a source of magnesium ions to the conditioned water, thereby depleting hydroxide in the conditioned water;
continuing addition of the source of magnesium ions, thereby solubilising the ultra-fine brucite and forming hydromagnesite; and recovering the hydromagnesite.
According to a further aspect of the invention there is provided a method for the production of hydromagnesite comprising:
providing water having carbonate alkalinity;
adding a solution comprising an ultrafine brucite solid and a source of magnesium ions to the water;
continuing the addition of the source of magnesium ions to the water, thereby solubilising the ultrafine brucite and forming hydromagnesite; and recovering the hydromagnesite.
The above preferred features and examples may be equally applicable to the above further aspects of the inventions and are explicitly incorporated into those aspects of the invention by reference.
In particular, according to these additional aspects of the invention the water may be conditioned to a carbonate:hydroxide ratio of at least 2:1, more preferably approximately 2:1.
The conditioning may further comprise the addition of a source of hydroxide to the water, for example an aqueous hydroxide, such as NaOH.
The source of magnesium ions is again preferably an aqueous magnesium, more preferably MgCh.
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The temperature of the water is again preferably higher than 55°C, with the temperature preferably being maintained throughout the method.
Again, in a specific example of these aspects of the invention, the water having carbonate alkalinity is coal seam gas brine. The coal seam gas brine may have a dissolved solids content of up to saturation point, for example up to about 30 wt%. The coal seam gas brine may be pre-treated prior to conditioning with the ultrafine brucite, such as with filtration of organics, scrubbing, concentration and/or reverse osmosis. For example, the coal seam brine may be pre-treated to remove unwanted components, such as silica and/or fluoride.
The method of these additional aspects of the invention may further comprise removing contaminating halides following formation of said hydromagnesite. The removed contaminated halides may comprise bromide and iodide and the removal preferably comprises acidification of water containing the halides and oxidation.
As with the first aspect of the invention, the above described methods may further comprise recovering remanent salt, such as NaCI, following removal of the hydromagnesite. Recovery of the hydromagnesite may comprise dewatering, washing and drying, as previously described.
The method may be applied in a batch process, semi-batch process, or a continuous process.
The method may comprise maintaining pH and/or Mg ion in the water by adjusting addition of hydroxide, if needed, to achieve a predetermined carbonate equilibria in the water.
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The invention also provides hydromagnesite when recovered or produced by a method as described above.
Throughout this specification, unless the context requires otherwise, the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated step or element or integer or group of steps or elements or integers, but not the exclusion of any other step or element or integer or group of steps, elements or integers. Thus, in the context of this specification, the term “comprising” is used in an inclusive sense and thus should be understood as meaning “including principally, but not necessarily solely”.
The present invention consists of features and a combination of parts hereinafter fully described and illustrated in the accompanying drawings, it being understood that various changes in the details may be made without departing from the scope of the invention or sacrificing any of the advantages of the present invention.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
To further clarify various aspects of some embodiments of the present invention, a more particular description of the invention will be rendered by references to specific embodiments thereof, which are illustrated in the appended drawings. It should be appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting on its scope. The invention will be described and explained with additional specificity and detail through the accompanying drawings in which:
FIG. 1 illustrates a chart that examines the solution chemistry of a known bicarbonate route for production of hydromagnesite.
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FIG. 2 illustrates a simplified flowchart of a method in accordance with an embodiment of the invention.
FIG. 3 illustrates a simplified flowchart of a method in accordance with an alternative embodiment of the invention.
FIG. 4 illustrates a simplified flowchart of a method in accordance with an alternative embodiment of the invention.
FIG. 5 illustrates a simplified flowchart of pre-treatments and post-treatments in accordance with embodiments of the invention.
FIG. 6 illustrates a graph of residual alkalinity with different sources of bases.
FIG. 7 illustrates a graph of endpoint results using various Ca:Mg ratios.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Calcium and magnesium behave very differently in bicarbonate, carbonate and hydroxide alkalinity. Also, carbonates generally tend to be very sensitive to changes in partial pressure of carbon dioxide (or dissolved carbon dioxide) and temperature. These attributes when combined with the solubility product can yield significant differences in the stability of precipitated compounds. The significant issues associated with calcium are apparent in, for example, precipitated calcium carbonate plants in paper mills which have significant scaling issues as there is enough solubility of the calcium carbonate to cause poor precipitation and scaling throughout plant equipment.
At low temperatures, for example 25°C, with the solubility product constants below, calcium carbonate is less soluble than magnesium carbonate, but at a
2018222897 28 Aug 2018 high pH where hydroxide is involved magnesium is less soluble than calcium. Therefore, from a traditional sense calcium carbonate is the preferred precipitant at a lower pH, for instance around 8. This is the reason the ocean has more magnesium in solution than calcium and exoskeletons are made of calcium 5 carbonates.
With this reasoning, increasing the temperature will favour calcium carbonate.
However, hydromagnesite is the dominant species of magnesium precipitation above a temperature of 55-65°C. Despite brucite initially being present in the 10 reaction, as magnesium becomes more available during the titration it will favour hydromagnesite due to the solubility and stability of hydromagnesite. Hydromagnesite is so favourable that magnesium will take hydroxide from solution and act as an ‘acid’ generating excessive hydrogen ions and thus carbon dioxide if not enough caustic is added. Despite this the hydromagnesite remains 15 incredibly stable in an aqueous solution evolving carbon dioxide.
| Calcium carbonate | CaCO3 | -2.8x10-9 |
| Calcium hydroxide | Ca(OH)2 | -5.5x10-6 |
| Magnesium carbonate | MgCO3 | -3.5x10-8 |
| Magnesium hydroxide | Mg(OH)2 | -1.8x10-11 |
| Dolomite | CaMg(CO3)2 | -10-17 |
| Hydromagnesite | Mg(CO3)4(OH)2.4H2O | -10-37 to 10- 40 |
Table 2: Solubility Product Constant
Consider the relation of concentration and the ksp:
2018222897 28 Aug 2018 [Solid Precipitant] = ksp x [Cation] x [Anion]
To increase the precipitation you can either increase the concentration of the precipitating cation or anion. Because the solubility of hydromagnesite is so low all of the reactants are driven down to very low levels i.e. 50 mg/L of Mg as Mg and 500mg/L of alkalinity as CaCCh.
For instance removing magnesium from solution as brucite we can add high levels of hydroxide to lower the magnesium to a very low level.
Referring to Figure 2, a preferred process is illustrated. First, conditioned brine 220 is prepared by adding sodium hydroxide 210 to an alkalinity brine 200. Before the hydroxide 210 is added, the alkalinity in the brine 200 is composed of carbonate (major) and bicarbonate (minor) alkalinity species.
Consider that there are X moles of carbonate ions, and Y moles of bicarbonate ions. The conditioned brine 220 advantageously has a molar ratio of carbonate ions to hydroxide ions of approximately 2:1. There are no bicarbonate ions present. To condition the brine, therefore, enough hydroxide should be added to convert any bicarbonate to carbonate and addition of hydroxide continued until the molar ratio of carbonate ions to hydroxide ions is 2:1.
The moles of hydroxide needed to condition the brine may be represented as follows:
Moles of NaOH required = moles of bicarbonate + 1/2*(moles of bicarbonate + moles of carbonate)
That is:
2018222897 28 Aug 2018
NaOH required = X + 1/2 *(X+Y)
When the conditioned brine 220 is achieved, a source of Mg2+ 230 is added to 5 the conditioned brine 220.
In an initial phase, all of the magnesium added reacts with any hydroxide species present in the conditioned brine 220 to form an ultrafine, gelatinous brucite solid io 240. This occurs as brucite is extremely insoluble when the solution pH is above 9.
No hydromagnesite forms until a maximum amount of brucite is present. At this point, all of the hydroxide has been consumed by the initial magnesium added. At 15 this point, the solution pH is approximately 9.5. From this point onwards, any further magnesium addition has a different effect.
It should be noted that the conditioned brine 220 has a pH above 11. Unconditioned brine 200 has a pH of around 9.8. Notwithstanding the additional 20 aspects of the invention described above and the processes of Figures 3-4 described below, adding conventional brucite to unconditioned brine or conditioned brine will not produce any hydromagnesite because the brucite is not able to dissolve (and therefore cannot react).
In the second phase of the reaction, the brucite is resolubilised 250 to form hydromagnesite. The mechanism is thought to be as follows:
Magnesium ions strip hydroxide of water molecules, which form free proton radicals:
2018222897 28 Aug 2018
Mg^ + 2HZO(O^ Mg(OH)Z(Qg) + 2H|tg)
The proton radicals convert the carbonate ions to bicarbonate ions, the affect is to lower the pH:
The solid brucite from the first phase of the overall reaction is resolubilised by the bicarbonate ions:
Mg(0H)2(s) + 2HCO3- -+ Mg(HC03)(0H>Q<?)+ CO3^+ H2O(!)
Hydromagnesite forms:
Hydromagnesite may then be recovered 260.
The overall reaction may be represented as follows:
+ (2NaOH + 4NazCO3 + xNaCl
-+ Mg5(OH)2(CO3J4.4HzO(s) + (x + 10)NaCl(o?)
This reaction is very efficient in the production of hydromagnesite. Virtually all of the carbonate (aka inorganic carbon) is converted to solid hydromagnesite at the endpoint of the reaction. There is very little or no residual magnesium ion remaining in solution. The only species remaining in solution (effectively) are sodium and chloride ions.
2018222897 28 Aug 2018
Referring to Figure 3, an alternative process is illustrated. According to this embodiment, which will be discussed in further detail in the accompanying examples, an alkalinity brine 300 is treated with a source of ultrafine brucite 310 to form a conditioned brine 320. As with the above described process, a source of Mg2+ 330 is added to the conditioned brine 220. This depletes OH’ in the brine 240. Further addition of Mg2+ 330 resolubilises the brucite 350 to form hydromagnesite, whereby the hydromagnesite may be recovered 360.
In a further alternative, as illustrated in Figure 4, a mixture of ultrafine brucite and Mg2+ 410 is added to alkalinity brine 400 and a conditioned brine 420 obtained. A source of Mg2+ 430 is then added to deplete OH- in the brine 440 and a source of Mg2+ 430 added to resolubilise the brucite 450 to form hydromagnesite, whereby the hydromagnesite may be recovered 460.
Pre-treatment and post-treatment steps, optional to the present invention are illustrated in Figure 5. Taking a feed of coal seam gas (CSG) brine 500’, pretreatment 500” includes filtering, scrubbing, concentrating and/or reverse osmosis processes. This produces alkalinity brine 500 for further processing as described above. Post-treatment may include recovery of NaCI 590 from the solution following recovery of hydromagnesite 560. Formation of a hydromagnesite product 580 may include dewatering, washing and drying processes 570.
Hereinafter, this specification will describe the present invention according to the preferred embodiments. It is to be understood that limiting the description to the preferred embodiments of the invention is merely to facilitate discussion of the present invention and it is envisioned without departing from the scope of the appended claims. Specifically, pre-treatment and post-treatment stages discussed in the following detailed description should be understood to be
2018222897 28 Aug 2018 described as optional stages that are not limiting on the scope of the central, essential stages of the method of the invention.
EXAMPLES
The following examples are provided for exemplification only and should not be construed as limiting on the invention in any way.
Differences in performance of different bases
A key attribute to preforming brucite at the same time as completing the hydromagnesite reaction is the generation of an ultrafine, colloidal, gelatinouslike brucite which is highly interactive with the bulk fluid. Other conventional forms of brucite (i.e. precipitated, dried and milled) are semi crystalline and are sheltered from being available for hydromagnesite formation.
Results of the following experiment are graphically illustrated in Figure 6.
An experiment was conducted using a feed stock of approximately 0.3 moles per litre sodium carbonate, to which a variety of bases were added. The bases included magnesium hydroxide (dried powder), magnesium oxide (dried powder), and magnesium chloride solution with precipitated magnesium hydroxide formed by adding NaOH added to magnesium chloride.
The bases were stoichiometrically added to the carbonate solution and the solution was monitored for alkalinity and magnesium. The data indicates that the magnesium hydroxide was not fully reacted and shows that availability of the magnesium and hydroxides is critical to pushing to a very good yield.
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It is considered that this provides evidence that having the initial brucite formed or provided as a hydrated dispersed gelatinous material is important to making the brucite physically available. It is thought that other forms of brucite may be chemically bound with layers of hydromagnesite such that the brucite is ‘hidden away’ from the bulk reaction. Over time the other bases could be used to completion, but carbon dioxide may then evolve as the base is not available to keep the alkalinity aligned with carbonate.
In the 2:1 ratio brine discussed above, which is generally of relatively large volume, the addition of magnesium disperses the brucite as evidenced by the apparent thickening of the bulk fluid. Once all of the brucite is consumed the fluid returns to a watery state due to the presence of hydromagnesite. Any disperse brucite freshly made is hydrated. It is considered that commercial or powdered brucite and magnesium oxide having larger crystals in a bulk solution, form a brucite layer which may react and then produce a hydromagnesite layer, “hiding” the rest of the hydroxide and magnesium from the bulk solution. Because the magnesium has an activity of 2, double the amount of hydroxide ions are kept from the bulk solution and thus substantial amounts of carbon dioxide are evolved as observed with the pre-brucite, conditioned with MgO and Mg(OH)2 reactions.
Sources of Magnesium and Caustic
Magnesium and caustic can be derived from the same source or from different sources. Hydroxide can come from, for example, magnesium oxide, magnesium hydroxide and sodium hydroxide. Magnesium hydroxide can be prepared by adding lime to a magnesium solution, such as seawater.
Sources of magnesium available from bitterns from the sea are in the form of magnesium chloride hexahydrate, or aquatic magnesium from concentrated sea
2018222897 28 Aug 2018 water brine from water reclamation plants, or from seawater itself. Aqueous magnesium will still be required to drive the reaction.
Some examples of using other sources of hydroxide are:
Magnesium Oxide
MgO + H2O -> Mg(OH)2
Mg(OH)2 + 4MgCI2 + 4NaCO3 + 4H2O - > Mg5(CO3)4(OH)2.4H2O + 4NaCI
Magnesium Hydroxide (Brucite)
Mg(OH)2 + 4MgCI2 + 4NaCO3 + 4H2O - > Mg5(CO3)4(OH)2.4H2O + 4NaCI
Impact of Calcium on Endpoint
An experiment was conducted replacing magnesium with calcium and the total hardness and total alkalinity was measured as a result of the replacement. The results are illustrated in Figure 7.
The alkalinity observed in the high Ca case was almost entirely hydroxide. This is because of the presence of ‘lime water’ (i.e. calcium hydroxide is fairly soluble). An excess of calcium and an excess of hydroxide will result in this. If you then add magnesium, brucite (Mg(OH2)) will be generated, which is insoluble. Calcium remains in the water, which is the driver for any residual hardness in the water.
The addition of calcium detrimentally results in an increase in alkalinity and an increase in hardness (primarily calcium). The results illustrate that the ksp of hydromagnesite (10Λ-40) is many orders of magnitude lower than that of calcium precipitates and brucite (10Λ-6 to 10M1).
2018222897 28 Aug 2018
Unless the context requires otherwise or specifically stated to the contrary, integers, steps or elements of the invention recited herein as singular integers, steps or elements clearly encompass both singular and plural forms of the recited 5 integers, steps or elements.
It will be appreciated that the foregoing description has been given by way of illustrative example of the invention and that all such modifications and variations thereto as would be apparent to persons of skill in the art are deemed to fall io within the broad scope and ambit of the invention as herein set forth.
Claims (15)
1. A method for the production of hydromagnesite comprising:
conditioning water having carbonate alkalinity with a source of hydroxide; adding a source of magnesium ions to the conditioned water, thereby forming an ultrafine brucite (Mg(OH)2) solid in the conditioned water;
continuing addition of the source of magnesium ions, thereby resolubilising the ultrafine brucite and forming hydromagnesite; and recovering the hydromagnesite.
2. A method according to claim 1, wherein the conditioned water has a carbonate:hydroxide ratio of at least 2:1, preferably approximately 2:1.
3. A method according to claim 1, wherein said source of hydroxide is an aqueous hydroxide, such as NaOH.
4. A method according to claim 1, wherein said source of magnesium ions is an aqueous magnesium, preferably MgCb
5. A method according to any one of the preceding claims, wherein the temperature of the conditioned water is higher than 55°C, preferably the temperature being maintained throughout the method.
6. A method according to any one of the preceding claims, wherein said water having carbonate alkalinity is coal seam gas brine.
7. A method according to claim 6, wherein said coal seam gas brine has a dissolved solids content of up to saturation point, for example up to about 30 wt%.
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8. A method according to claim 6 or 7, wherein said coal seam gas brine has been pre-treated prior to conditioning with said source of hydroxide, such as with filtration of organics, scrubbing, concentration and/or reverse osmosis.
9. A method according to claim 8, wherein said coal seam brine has been pre-treated to remove unwanted components, such as silica and/or fluoride.
10. A method according to any one of claims 6 to 9, further comprising removing contaminating halides following formation of said hydromagnesite.
11. A method according to claim 10, wherein said removed contaminated halides comprise bromide and iodide and said removal preferably comprises acidification of water containing said halides and oxidation.
12. A method according to any one of claims 6 to 11, further comprising recovering remanent salt, such as NaCI, following removal of said hydromagnesite.
13. A method according to any one of the preceding claims, wherein recovery of said hydromagnesite comprises dewatering, washing and drying.
14. A method according to any one of the preceding claims, wherein said process is a batch process, semi-batch process, or is continuous.
15. A method according to any one of the preceding claims, comprising maintaining pH and/or Mg ion in the conditioned water by adjusting addition of hydroxide, if needed, to achieve a predetermined carbonate equilibria in the conditioned water.
2018222897 28 Aug 2018
16. A method for the production of hydromagnesite comprising:
providing water having carbonate alkalinity;
adding an ultrafine brucite solid to the water to condition the water;
adding a source of magnesium ions to the conditioned water, thereby depleting hydroxide in the conditioned water;
continuing addition of the source of magnesium ions, thereby solubilising the ultra-fine brucite and forming hydromagnesite; and recovering the hydromagnesite.
17. A method for the production of hydromagnesite comprising:
providing water having carbonate alkalinity;
adding a solution comprising an ultrafine brucite solid and a source of magnesium ions to the water;
continuing the addition of the source of magnesium ions to the water, thereby solubilising the ultrafine brucite and forming hydromagnesite; and recovering the hydromagnesite.
18. A method according to claim 16 or 17, wherein the water is conditioned to a carbonate:hydroxide ratio of at least 2:1, preferably approximately 2:1.
19. A method according to claim 16 or 17, wherein conditioning further comprises addition of a source of hydroxide to the water, for example an aqueous hydroxide, such as NaOH.
20. A method according to claim 16 or 17, wherein said source of magnesium ions is an aqueous magnesium, preferably MgCL.
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21. A method according to any one of claims 16 to 20, wherein the temperature of the water is higher than 55°C, preferably the temperature being maintained throughout the method.
22. A method according to any one of claims 16 to 21, wherein said water having carbonate alkalinity is coal seam gas brine.
23. A method according to claim 22, wherein said coal seam gas brine has a dissolved solids content of up to saturation point, for example up to about 30 wt%.
24. A method according to claim 22 or 23, wherein said coal seam gas brine has been pre-treated prior to conditioning with said ultrafine brucite, such as with filtration of organics, scrubbing, concentration and/or reverse osmosis.
25. A method according to claim 24, wherein said coal seam brine has been pre-treated to remove unwanted components, such as silica and/or fluoride.
26. A method according to any one of claims 22 to 25, further comprising removing contaminating halides following formation of said hydromagnesite.
27. A method according to claim 26, wherein said removed contaminated halides comprise bromide and iodide and said removal preferably comprises acidification of water containing said halides and oxidation.
2018222897 28 Aug 2018
28. A method according to any one of claims 22 to 27, further comprising recovering remanent salt, such as NaCI, following removal of said hydromagnesite.
5
29. A method according to any one of claims 16 to 28, wherein recovery of said hydromagnesite comprises dewatering, washing and drying.
30. A method according to any one of claims 16 to 29, wherein said process is a batch process, semi-batch process, or is continuous.
31. A method according to any one claims 16 to 30, comprising maintaining pH and/or Mg ion in the water by adjusting addition of hydroxide, if needed, to achieve a predetermined carbonate equilibria in the water.
15 32. Hydromagnesite when produced by a method according to any one of claims 1 to 31.
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| GR1010709B (en) * | 2023-05-12 | 2024-06-19 | Εθνικο Κεντρο Ερευνας Και Τεχνολογικης Αναπτυξης (Ε.Κ.Ε.Τ.Α.), | One-step hydromagnesite nanoparticles production method performed in an intensified rotating bed arrangement furnished with filler |
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| GR1010709B (en) * | 2023-05-12 | 2024-06-19 | Εθνικο Κεντρο Ερευνας Και Τεχνολογικης Αναπτυξης (Ε.Κ.Ε.Τ.Α.), | One-step hydromagnesite nanoparticles production method performed in an intensified rotating bed arrangement furnished with filler |
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| AU2024204987A1 (en) | 2024-08-08 |
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