Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B33/00—Silicon; Compounds thereof
  • C01B33/20—Silicates
  • C01B33/36—Silicates having base-exchange properties but not having molecular sieve properties
  • C01B33/38—Layered base-exchange silicates, e.g. clays, micas or alkali metal silicates of kenyaite or magadiite type
  • C01B33/42—Micas ; Interstratified clay-mica products
• • 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
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B28—WORKING CEMENT, CLAY, OR STONE
  • B28C—PREPARING CLAY; PRODUCING MIXTURES CONTAINING CLAY OR CEMENTITIOUS MATERIAL, e.g. PLASTER
  • B28C1/00—Apparatus or methods for obtaining or processing clay
  • B28C1/02—Apparatus or methods for obtaining or processing clay for producing or processing clay suspensions, e.g. slip
  • B28C1/06—Processing suspensions, i.e. after mixing
  • B28C1/08—Separating suspensions, e.g. for obtaining clay, for removing stones; Cleaning clay slurries
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B33/00—Silicon; Compounds thereof
  • C01B33/20—Silicates
  • C01B33/26—Aluminium-containing silicates, i.e. silico-aluminates
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B33/00—Silicon; Compounds thereof
  • C01B33/20—Silicates
  • C01B33/36—Silicates having base-exchange properties but not having molecular sieve properties
  • C01B33/38—Layered base-exchange silicates, e.g. clays, micas or alkali metal silicates of kenyaite or magadiite type
  • C01B33/40—Clays
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B33/00—Silicon; Compounds thereof
  • C01B33/20—Silicates
  • C01B33/36—Silicates having base-exchange properties but not having molecular sieve properties
  • C01B33/46—Amorphous silicates, e.g. so-called "amorphous zeolites"
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/34—Silicon-containing compounds
  • C08K3/346—Clay
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
  • C09C1/40—Compounds of aluminium
  • C09C1/42—Clays
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/60—Particles characterised by their size
  • C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/22—Rheological behaviour as dispersion, e.g. viscosity, sedimentation stability

Definitions

• the invention relates to a method for cleaning clay suspensions, in particular ven bentonite suspensions for the purpose of obtaining the fine fractions.
• Naturally occurring clays such as Bentonites, usually contain begloit minerals, the grain size usually exceeds that of the clay particles and which are also generally harder than the clay dividers.
• These coarse particles are, for example, quartz, Glimner feldspar, calcite, dolomite pyrite, hematite, etc.
• Clay minerals that can be cleaned according to the invention include, for example, those of the structure type of swellable Montmorins and Montmorillonoids and clay minerals with species disorder (mixed-layer silicates).
• species disorder mixed-layer silicates
• the process according to the invention is preferably carried out from a suspension of a clay of the montmorillonite-beidellite series, preferably of bentonite.
• Bentonites can contain varying amounts of alkali or alkaline earth. While the American Wyoming-type bentonites are characterized by a high alkali content, the European bentonites contain more exchangeable calcium, which is why they are sometimes subjected to an alkali treatment to increase their swelling capacity. These alkaline-activated bentonites are also suitable as starting materials according to the invention.
• the acid treatment of the raw clay is generally known and is widely used for the production of oak.
• acids for the can. practically all acids are used, in particular mineral acids, such as hydrochloric acid, heavy acid, nitric acid and phosphoric acid, or organic acids such as acetic acid.
• the acid treatment is generally carried out in a dilute, aqueous suspension. But you can also make a so-called "dry digestion" by kneading the clay with relatively concentrated acids.
• the clay can also be treated with gaseous acids, such as hydrogen chloride or sulfur dioxide.
• gaseous acids such as hydrogen chloride or sulfur dioxide.
• the acid treatment is usually carried out at elevated temperatures.
• the acid treatment is preferably carried out with a mineral acid, such as hydrochloric acid or sulfuric acid, at elevated temperatures, preferably at about 90 to 100 ° C. or also under pressure.
• a mineral acid such as hydrochloric acid or sulfuric acid
• the duration of the acid treatment depends on the type and concentration of the acid and on the temperature.
• the acid treatment of the bentonite suspension prevents the gel formation of the clay minerals with an additional crushing effect of the active substance.
• the gait (accompanying minerals) usually goes through the process without crushing effect.
• the acid treatment is carried out until a specific BET surface area of at least 150 m 2 / g is reached.
• the output tone has a specific surface area of approximately 60-80 g / m 2 .
• the acid-treated clay generally has a micropore volume of less than 800 ⁇ of at least 0.13 ml / g and less than 140 ⁇ of at least 0.10 ml / g.
• at least 18% by weight of the A1 2 0 3 and Fe 2 O 3 content should have been removed, and at least 12% by weight of hydrated silica (soluble in soda) should also be present.
• the acid-treated clay suspension can be introduced directly into the hydrocyclone.
• the acid-treated clay is freed of excess acid and soluble salts prior to treatment in the hydrocyclone. This is conveniently done through the clay suspension and then washing it out. Interfering salts are especially the iron salts, which sometimes hydrolyze when washed out with water. For this reason, it is often advisable to wash out with dilute acid until no more iron can be found in the wash water. The residues of the acid can then be washed out with water. Residual amounts of iron salts can also be removed by washing out with dilute solutions of complexing agents. The washed material for the hydrocyclone treatment is then resuspended in water.
• Hydrocyclones designed according to the desired grain size are used to separate the coarse fractions from clay suspensions.
• a particle size of 15-20 ⁇ m is generally sufficient for most purposes. Size grain diameter is understood to mean that no particles larger than 15-20 ⁇ m are present in the finely divided cyclone overflow with 100% separation effect. This is about one with a diameter of 40 mm and an inlet nozzle about 3 x 10 mm.
• the pump pressure is around 2 to 5 atm.
• the dripping effect is usually less than 100%.
• the separating effect decreases considerably due to excessive underflow quantities and that the cyclone in the underflow and at the inlet nozzle sometimes clogs when the concentration of grain contents is too high, approximately 10 times the limit grain diameter.
• the process according to the invention is therefore generally carried out in such a way that the acid-treated bentonite suspension is pumped over a plurality of cyclone stages connected in series, the required separation limit being able to be doubled for the first stage.
• Such cyclones have an inner diameter of about 80 mm and are operated with about 1.5 to 3.5 atü pump pressure. This first cleaning course separates roughly 10% of coarse parts.
• the cyclone passage has a grain size of approximately 95% less than 32 ⁇ m.
• the yield in this stage is about 55%, so that the overall yield is generally between 45 and 55%.
• the division of the process into two steps also has the advantage that the cyclone run (coarse fractions) of the second stage can optionally be obtained as an independent product, for example as rapidly filtering bleaching earth.
• an untreated clay is used instead of this acid-treated clay, e.g. a sodium bentonite of the Wyoming type, in order to obtain a fine-grain fraction with a comparable particle size, a correspondingly diluted suspension must be used, i.e. one only comes to a solids concentration of about 30 g / liter.
• the suspension of fine particles obtained from the hydrocyclone can be worked up in a conventional manner, e.g. in that the solid particles are separated from the liquid by filtering or centrifuging.
• the damp cake can then be dried at moderate temperatures.
• the product obtained from the suspension of the acid-treated bentonite is very suitable as an adsorbent and bleaching agent for the refining of oils and fats and solvents, as a filler for paper, plastic, rubber, etc., also as a paper coating agent and for the production of catalysts and support material for Catalysts.
• the product is particularly suitable because of its small grain size and homogeneity as a color developer for carbon-free copying material.
• These color developers are applied as coating compositions to paper or typewriter tapes.
• Another sheet of paper contains an oil solution of a leuco dye, enclosed in microcapsules. If the microcapsules are destroyed by the typewriter type or by the pressure of a ballpoint pen, the released leuco dye reacts with the color developer
• the acid-treated material freed from the coarse fractions, can be loaded again with alkali or alkaline earth ions. But you get here generally no longer the starting material, since the acid treatment also removed the trivalent ions or part of them and the crystal lattice has undergone a certain change as a result of this treatment.
• the particle size of the products again loaded with alkali or alkaline earth ions is comparable to that of the acid-treated products; but they also have the surprising property that they act as ion exchangers and complexing agents.
• the loading with alkali or alkaline earth ions generally takes place in that the acid-treated products are heated in solutions of alkali or alkaline earth metal salts or hydroxides. When salts are used, alkaline solutions of salts, such as sodium carbonate or sodium borate, are preferred.
• Bentonite raw clay from the Bavarian deposits in the Moosburg-Mainburg-Landshut area is mixed with about 1000 meq of hydrochloric acid, based on 100 g of dry clay, and heated to about 95 ° C. for 8 hours. The portions dissolved are separated from the solid together with the excess acid. The acid-treated clay is washed out to a pH of about 3.5 to 5.
• the still moist material is converted into a suspension with a solids content of about 200 g / liter by adding water.
• the suspension is passed through two hydrocyclone stages and order, which are usually made from the coarse fractions above 25 / quartz, mica, feldspar, pyrite and hematite, largely freed.
• the slurry with the fine particles is filtered and the filter cake obtained is dried and milled at moderate temperatures.
• a non-acid-treated bentonite suspension of the Wyoming type was subjected to a hydrocyclone treatment to enrich the fines, the solids content of the suspension being at most 30 g / liter.
• the percentage of the fines in the starting material or in the hydrocyclone fines is given below depending on the solids content of the respective suspension.
• the viscosity of suspensions of the bentoniti raw clay and of the acid-treated clay obtained by the above procedure was also determined.
• a rotary viscometer from Haake, type Roto-Visco RV 11 with a rotating body MV I, was used for the measurements. The measurements were made with a shear rate of D-63 (sec -1 ) and D 570 carried out. The results below were
• the raw clay pretreated as in Example 1 is passed as a hot acid suspension, as is obtained after the acid treatment, with 2.0 atm into an acid-resistant hydrocyclone stage and largely freed from the coarse fractions above 35 / u.
• the results show an increase in the bleaching effect of the fines content.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Dispersion Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Materials Engineering (AREA)
• Geology (AREA)
• Engineering & Computer Science (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Health & Medical Sciences (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Silicates, Zeolites, And Molecular Sieves (AREA)
• Solid-Sorbent Or Filter-Aiding Compositions (AREA)
• Catalysts (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Paper (AREA)

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Citations (7)

• 1977
  • 1977-06-15 DE DE2727052A patent/DE2727052C2/de not_active Expired
• 1978
  • 1978-06-09 EP EP78100123A patent/EP0000129A1/de not_active Withdrawn
  • 1978-06-13 IT IT49840/78A patent/IT1105215B/it active
  • 1978-06-14 ES ES470774A patent/ES470774A1/es not_active Expired
  • 1978-06-15 JP JP7159278A patent/JPS546880A/ja active Pending

Patent Citations (7)

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