EP0553139A1 - Synthetic clays - Google Patents
Synthetic claysInfo
- Publication number
- EP0553139A1 EP0553139A1 EP91917639A EP91917639A EP0553139A1 EP 0553139 A1 EP0553139 A1 EP 0553139A1 EP 91917639 A EP91917639 A EP 91917639A EP 91917639 A EP91917639 A EP 91917639A EP 0553139 A1 EP0553139 A1 EP 0553139A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- size
- microns
- extrudates
- synthetic
- synthetic clay
- 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.)
- Ceased
Links
- 239000004927 clay Substances 0.000 claims abstract description 29
- 239000002245 particle Substances 0.000 claims abstract description 22
- 239000010457 zeolite Substances 0.000 claims abstract description 19
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 claims abstract description 14
- 229910021536 Zeolite Inorganic materials 0.000 claims abstract description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 13
- 239000000463 material Substances 0.000 claims abstract description 11
- 238000001035 drying Methods 0.000 claims abstract description 5
- 238000000034 method Methods 0.000 claims description 23
- 229910021647 smectite Inorganic materials 0.000 claims description 14
- 239000008187 granular material Substances 0.000 claims description 9
- 239000006185 dispersion Substances 0.000 claims description 8
- 238000001125 extrusion Methods 0.000 claims description 7
- 239000000203 mixture Substances 0.000 claims description 7
- 238000001914 filtration Methods 0.000 claims description 4
- 239000007787 solid Substances 0.000 claims description 4
- 230000003287 optical effect Effects 0.000 claims description 3
- 239000011236 particulate material Substances 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 claims description 2
- 238000012986 modification Methods 0.000 claims description 2
- 230000004048 modification Effects 0.000 claims description 2
- 238000005549 size reduction Methods 0.000 claims description 2
- 230000003197 catalytic effect Effects 0.000 abstract description 3
- AZJYLVAUMGUUBL-UHFFFAOYSA-A u1qj22mc8e Chemical compound [F-].[F-].[F-].[F-].[F-].[F-].[F-].[F-].[F-].[F-].[F-].[F-].[F-].[F-].[F-].[F-].[F-].[F-].[Na+].[Na+].[Na+].[Na+].[Na+].[Na+].[Na+].[Na+].[Na+].[Na+].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].O=[Si]=O.O=[Si]=O.O=[Si]=O.O1[Si](O2)([O-])O[Si]3([O-])O[Si]1([O-])O[Si]2([O-])O3.O1[Si](O2)([O-])O[Si]3([O-])O[Si]1([O-])O[Si]2([O-])O3.O1[Si](O2)([O-])O[Si]3([O-])O[Si]1([O-])O[Si]2([O-])O3.O1[Si](O2)([O-])O[Si]3([O-])O[Si]1([O-])O[Si]2([O-])O3.O1[Si](O2)([O-])O[Si]3([O-])O[Si]1([O-])O[Si]2([O-])O3.O1[Si](O2)([O-])O[Si]3([O-])O[Si]1([O-])O[Si]2([O-])O3 AZJYLVAUMGUUBL-UHFFFAOYSA-A 0.000 abstract description 3
- 235000008429 bread Nutrition 0.000 abstract 1
- 239000000047 product Substances 0.000 description 18
- 239000012065 filter cake Substances 0.000 description 8
- 230000015572 biosynthetic process Effects 0.000 description 7
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 6
- 229910052500 inorganic mineral Inorganic materials 0.000 description 4
- 239000011707 mineral Substances 0.000 description 4
- 229910052680 mordenite Inorganic materials 0.000 description 4
- 238000003786 synthesis reaction Methods 0.000 description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 238000001354 calcination Methods 0.000 description 3
- 150000001768 cations Chemical class 0.000 description 3
- 239000011521 glass Substances 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- 229940094522 laponite Drugs 0.000 description 3
- XCOBTUNSZUJCDH-UHFFFAOYSA-B lithium magnesium sodium silicate Chemical compound [Li+].[Li+].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[Na+].[Na+].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].O1[Si](O2)([O-])O[Si]3([O-])O[Si]1([O-])O[Si]2([O-])O3.O1[Si](O2)([O-])O[Si]3([O-])O[Si]1([O-])O[Si]2([O-])O3.O1[Si](O2)([O-])O[Si]3([O-])O[Si]1([O-])O[Si]2([O-])O3.O1[Si](O2)([O-])O[Si]3([O-])O[Si]1([O-])O[Si]2([O-])O3.O1[Si](O2)([O-])O[Si]3([O-])O[Si]1([O-])O[Si]2([O-])O3.O1[Si](O2)([O-])O[Si]3([O-])O[Si]1([O-])O[Si]2([O-])O3 XCOBTUNSZUJCDH-UHFFFAOYSA-B 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 239000000377 silicon dioxide Substances 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 229920000388 Polyphosphate Polymers 0.000 description 2
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 239000012736 aqueous medium Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000003495 polar organic solvent Substances 0.000 description 2
- 239000001205 polyphosphate Substances 0.000 description 2
- 235000011176 polyphosphates Nutrition 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 239000001117 sulphuric acid Substances 0.000 description 2
- 235000011149 sulphuric acid Nutrition 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 1
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 1
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 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 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical compound [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- IDCBOTIENDVCBQ-UHFFFAOYSA-N TEPP Chemical compound CCOP(=O)(OCC)OP(=O)(OCC)OCC IDCBOTIENDVCBQ-UHFFFAOYSA-N 0.000 description 1
- 239000011149 active material Substances 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 150000001342 alkaline earth metals Chemical group 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- 239000004411 aluminium Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- JYIBXUUINYLWLR-UHFFFAOYSA-N aluminum;calcium;potassium;silicon;sodium;trihydrate Chemical compound O.O.O.[Na].[Al].[Si].[K].[Ca] JYIBXUUINYLWLR-UHFFFAOYSA-N 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000007900 aqueous suspension Substances 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- VNSBYDPZHCQWNB-UHFFFAOYSA-N calcium;aluminum;dioxido(oxo)silane;sodium;hydrate Chemical compound O.[Na].[Al].[Ca+2].[O-][Si]([O-])=O VNSBYDPZHCQWNB-UHFFFAOYSA-N 0.000 description 1
- 125000002091 cationic group Chemical group 0.000 description 1
- 239000002734 clay mineral Substances 0.000 description 1
- 229910001603 clinoptilolite Inorganic materials 0.000 description 1
- 230000002860 competitive effect Effects 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- GUJOJGAPFQRJSV-UHFFFAOYSA-N dialuminum;dioxosilane;oxygen(2-);hydrate Chemical compound O.[O-2].[O-2].[O-2].[Al+3].[Al+3].O=[Si]=O.O=[Si]=O.O=[Si]=O.O=[Si]=O GUJOJGAPFQRJSV-UHFFFAOYSA-N 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 150000002222 fluorine compounds Chemical class 0.000 description 1
- -1 for example Substances 0.000 description 1
- 238000005469 granulation Methods 0.000 description 1
- 230000003179 granulation Effects 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 229910000271 hectorite Inorganic materials 0.000 description 1
- KWLMIXQRALPRBC-UHFFFAOYSA-L hectorite Chemical compound [Li+].[OH-].[OH-].[Na+].[Mg+2].O1[Si]2([O-])O[Si]1([O-])O[Si]([O-])(O1)O[Si]1([O-])O2 KWLMIXQRALPRBC-UHFFFAOYSA-L 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 150000002500 ions Chemical group 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 150000002681 magnesium compounds Chemical class 0.000 description 1
- 159000000003 magnesium salts Chemical class 0.000 description 1
- 235000012054 meals Nutrition 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 229910052901 montmorillonite Inorganic materials 0.000 description 1
- 239000012452 mother liquor Substances 0.000 description 1
- 229910000273 nontronite Inorganic materials 0.000 description 1
- 238000000424 optical density measurement Methods 0.000 description 1
- 239000011368 organic material Substances 0.000 description 1
- 238000010951 particle size reduction Methods 0.000 description 1
- 229910052615 phyllosilicate Inorganic materials 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000011435 rock Substances 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 229910000275 saponite Inorganic materials 0.000 description 1
- 229910000276 sauconite Inorganic materials 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 150000003377 silicon compounds Chemical class 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 229910000269 smectite group Inorganic materials 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 150000003388 sodium compounds Chemical class 0.000 description 1
- 229910001415 sodium ion Inorganic materials 0.000 description 1
- 229910052938 sodium sulfate Inorganic materials 0.000 description 1
- 235000011152 sodium sulphate Nutrition 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 230000008961 swelling Effects 0.000 description 1
- 238000000870 ultraviolet spectroscopy Methods 0.000 description 1
- 230000004580 weight loss Effects 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
- B01J21/16—Clays or other mineral silicates
-
- B01J35/19—
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B33/00—Clay-wares
- C04B33/02—Preparing or treating the raw materials individually or as batches
- C04B33/20—Preparing or treating the raw materials individually or as batches for dry-pressing
Abstract
Le traitement d'argiles synthétiques, tel que l'hectorite synthétique, qui consiste à former un pain comprimé de l'argile, à l'extruder à travers des trous de diamètre restreint et à faire sécher et réduire en taille les éléments extrudés dans la plage comprise entre 200 à 2000 microns permet d'améliorer leur capacité de dispersion dans l'eau. Des particules d'un autre matériau, tel qu'un zéolithe actif de manière catalytique peuvent être comprises dans le pain comprimé et les éléments extrudés séchés peuvent être utilisés à des fins catalytiques.The treatment of synthetic clays, such as synthetic hectorite, which consists of forming a compressed loaf of clay, extruding it through holes of small diameter, and drying and reducing in size the elements extruded in the clay. range between 200 to 2000 microns improves their ability to disperse in water. Particles of another material, such as a catalytically active zeolite can be included in the compressed bread and the dried extrudates can be used for catalytic purposes.
Description
Synthetic clavs
This invention relates to synthetic clays.
The synthetic analogues of a number of clay minerals, for example the smectites, have been synthesised.
Smectite minerals may be defined as a group of minerals or phyllosilicates of the 2:1 layer type with the general formulae:
(Mm+(x+y)/-nnH20)(R3+2-yR2+y) (Si4-χAlx)O10(OH)2
(dioctahedral) (M +(X+y)/mnH20) (R2+3_.yLi+ y) (Si4_xAlx)O10(OH)2
( rioctahedral) (Mm+(x-y)/mnH2O)(R2+3_yR3+y)(si4_χAlχ)O10(OH)2
( rioctahedral)
where Mm+ represents exchangeable cations, such as Ca++, Mg++, having a valency m, necessary to satisfy the negatively charged lattice, R2+ represents magnesium or iron and R3+ represents aluminium or iron. The smectite group of minerals includes the mineral sub-groups montmorillonite, beidellite, nontronite, saponite, hectorite and sauconite.
There exist a number of processes for producing synthetic smectite clays. British Patent Specifications Nos. 1054111 and 1213122 describe forming such synthetic clays by precipitation from an alkaline solution containing
SUBSTITUTESHEET
a magnesium salt, a sodium compound and a silicon compound and treating the precipitate under hydrothermal pressure conditions until the precipitated product has crystallised. British Patent Specification No. 1432770 describes forming synthetic smectite clays by forming an aqueous suspension of a water insoluble magnesium compound containing lithium and fluorine compounds, if desired, and forming in the suspension a precipitate of silica followed by treatment under hydrothermal pressure conditions to achieve crystallisation. In each process the crystalline product may be separated from the mother liquor, washed and dried. The disclosures of British Patent Specifications Nos. 1054111, 1213122 and 142770 in relation to methods for the production of synthetic smectite clays is incorporated herein by reference. Preferably the clay utilised in the practice of the invention described hereafter is a synthetic hectorite which may be produced according to the disclosures of any of the above identified patent specifications. A suitable synthetic hectorite is available from Laporte Industries Limited under the Trade Name Laponite. Any other synthetic clay, whether or not a smectite and whether or not manufactured according to the above identified disclosures may alternatively be utilised.
Synthetic clays are generally manufactured to an ultimate particle size of about 25 nanometers and supplied as a powdered product having a particle size (diameter) substantially wholly below 250 microns and generally at least 75% by weight below 75 microns in diameter. Synthetic smectite clays so manufactured can display rheological properties which are of a high order and can be relatively easy to disperse in aqueous media.
The present invention provides a method for processing synthetic clays which can lead to an improvement in certain properties. The invention also provides a form of synthetic clays which can possess said improved properties.
SUBSTITUTESHEET
The process according to the present invention comprises forming a compressed cake of particles of the synthetic clay, extruding the compressed cake through restricted diameter holes to form extrudates and drying the extrudates. The invention is preferably practised by dispersing the synthetic clay in water which may contain a proportion, preferably a minor proportion, of a polar organic solvent or other organic material, filtering the dispersion under a pressure of at least 4 bar to give a compressed filter cake having a solids content of at least 15% by weight and extruding the compressed filter cake material. The extrudates so formed may be dried and reduced preferably to a particle size of from 200 to 2000 microns to give a product dispersible in aqueous media. Alternatively, according to a further aspect of the invention, a mixture of the compressed filter cake material with particles of another material, for example of a zeolite having catalytic activity, may be extruded and the extrudates dried with or without particle size reduction and calcined to give aggregates of the other material for example catalytically active aggregates of zeolite.
The terms "synthetic smectite" or "synthetic clay" are used to include those clays which have been ion exchanged to a different cationic form, from that in which they were synthesised, for example to an alkali metal or alkaline earth metal form or to an organophilic form where the exchange cation may be an organic ammonium, phosphoniu or other onium cation.
Additives may be present in a synthetic clay product treated according to the invention. For example, a peptiser such as polyphosphate may be included to enable the synthetic clay to form a stable solution. Suitable polyphosphates are sold under the Trade Name "Tetron".
The filtration pressure is an important factor in the practice of the present invention and is preferably at least
SUBSTITUTESHEET
5 bar and particularly preferably at least 6 bar. An upper pressure limit of 10 bar or even 8 bar may suffice. The input to the filter press is preferably a dispersion of a washed crystalline synthetic clay product which may be washed but as yet undried synthesis product or which may be a redispersion of a previously washed and dried powdered product. The solids content achieved by filtration according to the invention is preferably at least 17% but maybe up to 21% or even 25% by weight or above consistant with the ability to extrude the filter cake material. The term 'filter' is used herein to encompass means of dewatering a slurry or aqueous dispersion by the application of pressure. The invention does not encompass the extrusion of a product made merely by mixing a dry synthetic clay with a quantity of water corrsponding to that in the compressed filter cake material.
The extrusion of the compressed filter cake material is preferably performed using hole diameters of from 2 to 10 mm preferably from 5 to 7 mm although a larger diameter product is required the upper limit of 10 mm may be exceeded. However, the pressure developed during extrusion is a material factor in the practice of the present invention and it is therefore preferred that the hole diameter be selected so as to cause the development of sufficient extrusion pressure to give the required product properties. In the practice of this invention a slit having a smaller dimension of 2 to 10 mm is regarded as being equivalent to a series of holes of the same diameter and the term "hole" is therefore not intended to be construed narrowly. The extrusion apparatus may include hydraulic rams as a means for developing a sufficient extrusion pressure and the extrudates may be received on a moving bed.
One effect of operating according to some or all of the indications given above is that the extrudates, on drying tend to disintegrate in such a manner that a product within the preferred size range may be achieved by using a
SUBSTITUTESHEET
relatively low energy size reduction means. Product in that size range can show improved dispersibility properties.
The extrudates may be dried in a tray drier, or other suitable drier, at a temperature preferably of from 80 to 150°C but particularly preferably of from 90 to 125°C. The dried extrudates may be reduced in size by means of a suitble mill such as a hammer mill for example a Raymond mill or a pin type mill for example an Attritor mill. The words Raymond and Attritor are Trade Names.
The reduced size extrudates are preferably in the size range of 200 to 2000 microns. Particularly preferably the extrudates are at least 212 microns for example, most suitably, at least 250 microns and particularly preferably not more than 1200 microns, for example very suitably not more than 1000 microns in size. The presence of a proportion of extrudates having sizes outside these ranges, for example 10% by weight or even up to 25% by weight or more while it may result in a reduced dispersion performance, does not depart from the spirit of this invention. The grinding time should preferably be kept to a minimum to achieve the desired particle size ranges to avoid undue fracture of the granules. Preferably a fraction of granules having the desired particle size range is removed on a sieve, and the oversize particles are recycled, on a continuous or discontinuous basis.
As foreshadowed above the synthetic clay, as extruded, may contain a proportion of a particulate active material such as a zeolite. Alternatively the particulate material may be any siliceous or metallosiliceous substance, for example a natural clay or ground rock, of which it may be desired to form aggregates.
The term "zeolite" is used broadly to include not only naturally occurring zeolites such as clinoptilolite but also both low silica and high silica families of synthetic
SUBSTITUTESHEET
zeolites such as, for example, zeolites A, X and Y, the ZSM series of zeolites and other families of zeolites competitive with, similar to or modifications of any of the above. The present invention is also particularly concerned with the zeolite mordenite which may be produced, for example, by the process described in United States Patent Specification No. 3436174 and other specifications of the Norton Company which zeolite is widely used in shaped form.
The proportion of synthetic clay in admixture with the zeolite is suitably from 5 to 30% but preferbly from 10% to 25% based on the dry weight of the clay and the zeolite. The mixture may be wetted using water or a mixture of water with a minor quantity of a polar organic solvent in a quantity to provide a weight loss on drying and calcination preferably of from 30 to 60% particularly preferably 40 to 50% by weight.
The shaping is preferably accomplished using an extruder, for example a Buss (Trade Name) extruder. Preferably only the co-kneader part of the Buss extruder is used.
The extrudates may be dried as above taught to remove free moisture at and are then preferably calcined. Synthetic clays may remain substantially stable to calcination temperatures up to about 700°C and this temperature is preferably not exceeded. Preferably the calcination is conducted at from 500 to 650°C for a time of from 30 minutes to 4 hours, particularly preferably of from 1 hour to 3 hours.
Certain features tend to augment the effect of the present invention and one or more of these are preferably used therein:
w'__τ _~; \Z* - - - '—,- » --.- _-i - ._-._-- I
i) The synthetic clay contains fluorine included during synthesis or has been washed with a dilute alkali meal fluoride solution after synthesis and after washing free of salts formed during synthesis.
ii) The synthetic clay and/or any zeolite which is used in conjunction with it and particularly mordenite if the latter is used is in the H+ form which may be attained, for example, by treating with sulphuric or hydrochloric acid for example sulphuric acid having a concentration of 5 to 10% w/w, at an elevated temperature, for example from 25 to 50°C followed by washing to remove displaced sodium ion.
iii) The required water content of the mixture of synthetic clay and of zeolite particles to be extruded is achieved by adding an aqueous solution of a base for example of sodium hydroxide which solution may have a concentration of from 0.5 to 1.5 preferably 1.0 Molar.
Calcined aggregates of zeolites produced by including a zeolite in a synthetic clay granulation process according to this invention, for example granules containing hydrogen mordenite or sodium mordenite, show excellent physical integrity, a high pore volume comparable with that of the unpelleted zeolite and possess a high degree of purity with respect to possible contaminants such as iron which could interfere with catalytic applications. Such aggregates are preferably calcined at a temperature no greater than 600°C for a satisfactory combination of properties.
The invention will now be more specifically described by reference to the following Examples which are not intended to be limitative thereon.
A synthetic smectite clay product, available from Laporte Industries Limited under the Trade Name Laponite, in
SUBSTITUTESHEET
the form of a powder of which 100% was less than 212 microns wsa dispersed in water at a concentration of 10% wt and filtered in a Hoechst filter press using a pressure of 6 bar to give a filter cake having a solids content of 21% wt. This filter cake was extruded through a steel plate having a plurality of holes of 6 mm diameter and the extrudates so formed were dried at 105°C for 100 minutes. The dried extrudates were milled under varying conditions on a Raymond Mill to give a series of 4 samples having the size ranges <212 microns, 212 to <710 microns, 710 to <1200 microns and 1200 to <2000 microns. These samples were dispersed in demineralised water at a concentration of 1% wt and the optical density of the dispersions was measured by absorption spectrophotometry at various time intervals to determine the relative ease of dispersion of the samples.
The results of the optical density measurements are given in Table I below.
Table 1 Particle Size Distribution (microns)
212-710 μm 710-1200 μm 1200-2000 μm
In a similar manner the rate of dispersion of a powder of the same synthetic smectite having a particle size 100% below 212 microns which had not been processed according to this invention was compared with that of particles of the same synthetic smectite having a particle size in the range 250-1000 microns manufactured according to the invention, each at a concentration of 2% by weight in water. The variation of the optical density with time of each of these materials was measured and expressed in graphical form in Figure I attached hereto.
It is seen from Figure I that the dispersibility of the powder was the lower.
The rate of gel formation of samples of a synthetic smectite both processed according to this invention but having different particle size ranges was compared. The apparatus was a glass cylinder having a nominal capacity of 120 cπ.3 which was arranged for end over end rotation at a rate of 90 inversions/minute. The cylinder contained a glass sphere of 5 g mass and 15 mm diameter. 95 g of demineralised water containing 1.128 g of sodium sulphate/litre was introduced into the cylinder followed by 5 g of Laponite swelling synthetic smectite extrudates which had been processed according to this invention. The test was separately performed for product having a particle size of 100% below 250 microns with at least 75% below 150 microns and product having a particle size of 250 to 1000 microns and was repeated for 25 samples of each. The test was conducted by measuring the time taken for gel formation to become sufficiently marked to prevent the glass sphere striking the end of the cylinder as a result of inversion of the cylinder in the course of rotation. The times for the samples were averaged and the average for the smaller article size product normalised to 100. The larger particle size product (250-1000 microns) was found to achieve gel formation in 85% of the normalised time.
SUBSTITUTESHEET
Claims
1. A process for the production of synthetic clay granules said process being characterised by forming a compressed cake of particles of the synthetic clay, extruding the compressed cake through restricted diameter holes to form extrudates drying the extrudates and size reducing the dried extrudates.
2. A process as claimed in claim 1 wherein the synthetic clay is dispersed in water and the dispersion is filtered under a pressure of at least 4 bar to give a compressed cake having a solids content of at least 15% by weight.
3. A process as claimed in Claim 1 or 2 wherein the dried extrudates are reduced in size to a particle size of 200 to 2000 microns.
4. A process as claimed in claim 3 wherein the dried extrudates are reduced in size to a particle size of 250 microns to 1200 microns.
5. A process as claimed in claim 2 wherein the filtration is conducted at a pressure of up to 10 bar.
6. A process as claimed in any preceding claim wherein the particles of synthetic clay used to form the compresed cake are below 250 microns in size with at least 75% by weight below 150 microns in size.
7. A process as claimed in any preceding claim wherein the restricted diameter holes are from 2 mm to 10 mm in diameter.
8. A process as claimed in any preceding claim wherein the synthetic clay is a smectite.
SUBSTITUTESHEET
9. A process as claimed in one of claims 1-8 wherein the synthetic clay is formed into a mixture with a another material in particulate form before extrusion.
10. A process as claimed in claim 9 wherein the particulate material is a zeolite.
11. A process as claimed in claim 9 or 10 wherein the proportion of synthetic smectite in the said mixture is from 5 to 30% by weight.
12. A process as claimed in any one of claims 9 to 11 wherein the mixture of synthetic clay and other particulate material is extruded through holes hving diameters of from 1 mm to 4mm.
13. A process as claimed in claim 12 wherein the dried size reduced extrudates are calcined.
14. A modification of a process as claimed in claim 13 wherein the dried extrudates are calcined without size- reduction.
15. Granules of a synthetic clay showing a reduced optical density with respect to the original particles of the synthetic clay from which the granules are formed when dispersed in water the granules being characterised by being from 200 to 2000 microns in size.
16. Granules as claimed in claim 15 being from 250 to 1200 microns in size.
17. Granules as claimed in claim 15 or 16 produced by the process of any one of claims 1 to 14.
SUBSTITUTESHEET
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB909022474A GB9022474D0 (en) | 1990-10-17 | 1990-10-17 | Synthetic smectite clays |
| GB9022474 | 1990-10-17 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| EP0553139A1 true EP0553139A1 (en) | 1993-08-04 |
Family
ID=10683823
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP91917639A Ceased EP0553139A1 (en) | 1990-10-17 | 1991-10-07 | Synthetic clays |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0553139A1 (en) |
| JP (1) | JPH06501908A (en) |
| AU (1) | AU8638291A (en) |
| CA (1) | CA2094235A1 (en) |
| GB (1) | GB9022474D0 (en) |
| MX (1) | MX9101577A (en) |
| WO (1) | WO1992006783A1 (en) |
| ZA (1) | ZA917838B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19541481A1 (en) * | 1995-11-07 | 1997-05-15 | Erlus Baustoffwerke | Ceramic granules and process for making the same |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2952888A (en) * | 1955-07-15 | 1960-09-20 | Houdry Process Corp | Method for clay extrusion |
| NL282438A (en) * | 1961-08-26 | |||
| US4226743A (en) * | 1979-03-12 | 1980-10-07 | W. R. Grace & Co. | Silica-alumina hydrogel catalyst |
-
1990
- 1990-10-17 GB GB909022474A patent/GB9022474D0/en active Pending
-
1991
- 1991-10-01 ZA ZA917838A patent/ZA917838B/en unknown
- 1991-10-07 WO PCT/GB1991/001737 patent/WO1992006783A1/en not_active Application Discontinuation
- 1991-10-07 EP EP91917639A patent/EP0553139A1/en not_active Ceased
- 1991-10-07 JP JP3515979A patent/JPH06501908A/en active Pending
- 1991-10-07 AU AU86382/91A patent/AU8638291A/en not_active Abandoned
- 1991-10-07 CA CA002094235A patent/CA2094235A1/en not_active Abandoned
- 1991-10-14 MX MX9101577A patent/MX9101577A/en unknown
Non-Patent Citations (1)
| Title |
|---|
| See references of WO9206783A1 * |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH06501908A (en) | 1994-03-03 |
| MX9101577A (en) | 1992-06-05 |
| CA2094235A1 (en) | 1992-04-18 |
| GB9022474D0 (en) | 1990-11-28 |
| ZA917838B (en) | 1992-06-24 |
| AU8638291A (en) | 1992-05-20 |
| WO1992006783A1 (en) | 1992-04-30 |
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