US3290161A - Clay bleaching - Google Patents

Clay bleaching Download PDF

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Publication number
US3290161A
US3290161A US313763A US31376363A US3290161A US 3290161 A US3290161 A US 3290161A US 313763 A US313763 A US 313763A US 31376363 A US31376363 A US 31376363A US 3290161 A US3290161 A US 3290161A
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United States
Prior art keywords
clay
bleaching
borohydride
slurry
brightness
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US313763A
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English (en)
Inventor
Fred R Sheldon
Jr William H Kibbel
James E Kressbach
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FMC Corp
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FMC Corp
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Publication date
Application filed by FMC Corp filed Critical FMC Corp
Priority to US313763A priority Critical patent/US3290161A/en
Priority to AT803464A priority patent/AT248944B/de
Priority to ES304496A priority patent/ES304496A1/es
Priority to GB40124/64A priority patent/GB1086718A/en
Application granted granted Critical
Publication of US3290161A publication Critical patent/US3290161A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F7/00—Compounds of aluminium
    • C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
    • C01F7/46—Purification of aluminium oxide, aluminium hydroxide or aluminates
    • 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
    • C04B33/04—Clay; Kaolin
    • C04B33/06—Rendering lime harmless
    • 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
    • C04B33/10—Eliminating iron or lime
    • 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
    • C04B33/30—Drying methods
    • 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
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/60—Optical properties, e.g. expressed in CIELAB-values

Definitions

  • This invention relates to the bleaching and refining of clays, and more particularly to a method of treating clays which increases their brightness and retains their desirable physical properties.
  • Clays particularly refined kaolins, .are employed in a variety of uses such as fillers and finishing agents for papers and paper-boards, as base ingredients and as fillers for the molding of electrical and other ceramic or plastic products, and as finishing agents for a variety of articles.
  • a clay be highly reflective, that is, that it have a high degree of brightness as measured on the basis of percent of light reflectance.
  • the clay have a low and uniform shear viscosity to permit optimum and reproducible processing in utilization; the electrical charges on the clay particles affect viscosity, and must be retained to as great an extent as possible.
  • the oxidizing bleaches for example chlorine bleaching agents such as chlorine dioxide, hypochlorites and the like, and active oxygen bleaches such as hydrogen peroxide, sodium peroxide and the organic peroxides, have been applied to this problem, as have the reducing bleaches such as the oxalates and the low oxidation state sulfur compounds.
  • the processing is carried out at a pH of about 2.5 to 5, and preferably about 3 to 3.5. Where necessary mineral acids such as sulfuric acid or other acids are employed 320,161 Patented Dec. 6, 1966 to provide this pH.
  • the operating temperature used is between about 40 and 200 F., and preferably between 70 and 180 F.
  • the bisulfite is used in the amount of about 5.6 times the amount of borohydride, within the above re-cited ranges. Use of substantially more than this amount does not improve bleaching, and use of less is apt to provide less bleaching than normally could be obtained with the given amount of borohydride.
  • This process provides a bleached clay having a higher degree of brightness than isprovided by any other method known to us.
  • the excellence of this bleach is quite unexpected; when the borohydride is employed in herein amounts alone in an attempt to bleach clay, substantially no brightness increase is obtained, and in some cases the brightness is reduced. This is despite the fact that sodium borohydride is known as a reducing bleaching agent'for some materials. Likewise, the bisulfite alone provides no brightness improvement.
  • the clay bleached by the herein process is a hydrated alumina silicate, preferably kaolin.
  • hydrated alumina silicate clays for example the bentonites, the montmorillonites and the like, can be treated by the present process, and such clays are intended to be included with-in the scope of this invention.
  • the clay is prepared for bleaching by a wash, which is carried out by dispersing the clay in water, for example with the aid of caustic or a phosphate such as sodium hexametaphosphate, and washing it to remove siliceous impurities such as sand, mica and the like.
  • a wash which is carried out by dispersing the clay in water, for example with the aid of caustic or a phosphate such as sodium hexametaphosphate, and washing it to remove siliceous impurities such as sand, mica and the like.
  • This employed in clay bleaching to reduce the amount of bleach needed and to cleanse the clay.
  • the washed clay has a color depending on its grade, and this color will range anywhere from a blue gray to tan up to a near white.
  • the clay is slurried in water to provide a slurry having a clay concentration of about 5 to and preferably about 15 to 35%, by weight of clay in the water.
  • This slurry is then treated by addition to it of an alkali bisulfite in an amount to provide about 0.7 to 5.6, and preferably 2 to 4.5, pounds of the bisulfite per'ton of the clay.
  • the bisulfite can be introduced in any physical form, although it is preferred to introduce it dry.
  • the metabis-ulfiteNa S O converts in aqueous solution by addition of water to the normal bisulfite, NaHSO
  • either of these bisulfites may be employed.
  • the bisulfite be in solution in the aqueous phase of the clay slurry, and it may be introduced in solid form, in slurry form or in solution, so long'as it dissolves in the aqueous system.
  • additional agents useful in dispersing the clay for example phosphates commonly used in clay processing, may be employed.
  • the bisulfites found to be particularly useful in this process are the alkali metal, alkaline earth metal and ammonium bisulfites, particularly the sodium, potassium, lithium, magnesium and ammonium bisulfites, and more particularly the alkali metal bisulfites.
  • the bisulfites may have associated with them substantial amounts of sulfites of ammonia or one of these metals without detriment; at the pH of the present solutions the sulfite converts to bisulfite.
  • the alkali borohydride is a solid, and normally is introduced in this form, since in aqueous solutions it tends to decompose. It is possible, however, to introduce this reagent in its aqueous solution provided the pH of the solution is maintained slightly alkaline prior to use by addition of an inert alkaline material such as sodium hydroxide, sodium carbonate and the like.
  • Preferred alkali borohydrides for use herein are the alkali metal borohydrides, particularly the sodium and potassium borohydrides, although any water soluble alkaline borohydride, for example magnesium and the like borohydrides can be used.
  • the alkali borohydride is employed in the amount of about 0.125 to 1, and preferably about 0.36 to 0.82, pound per ton of clay. Normally not more than about one part by weight of the borohydride is used for each 5.6 parts by weight of the bisulfite. It is important to note that use of these amounts of borohydride, or even more, in the absence of the bisulfite is ineffective to accomplish eifective bleaching of clays.
  • the temperature employed in the course of this process ranges from about ambient temperatures to about 200 F., and preferably from about 70 to 180 F. When elevated temperatures within this range are employed, the bleaching and refining operation proceeds rapidly, so that it is especially suited to continuous operation. Operation at lower temperatures within the above range is particularly useful, however, in instances where it is not desired to install heating equipment or for other operating reasons. Operation above about 200 F. tends to decompose the active reagents in the system and therefore is undesirable economically.
  • one of the principal advantages of the herein process is its ability to bleach and refine clay at temperatures encountered in water supplies even during the cold seasons. Thus it is possible to bleach clay by this process even with water as cold as about 40 F., water temperatures encountered in some areas.
  • the pH of the reaction system is maintained at about 2.5 to 5, and preferably at about 3 to 3.5. Operation below about pH 2.5 results in dissolution of substantial amounts of aluminum ion from the clay, whereas when the reaction is carried out above about pH 5 the brightness of the bleached clay is reduced. Where necessary, mineral acids, preferably sulfuric acid, are added to adjust the pH to the herein levels.
  • the concentration of the clay slurry during processing is not critical. It is desirable, however, to have as high a concentration of clay and bleaching agents as is possible consistent with eflicient and uniform contact of reactants, and to this end concentrations of from 5 to 70%, and preferably to 35%, by weight of clay are preferred.
  • the process of this invention operates in either a continuous or a batch fashion, in either case rapidly.
  • This speed of the reaction may be the reason for the excellent retention of physical properties of the clay, for example retention of its rheological properties. It has been found that overall the process will operate in about 30 minutes at 70 F., and in only about minutes at 120 F., whereas the operation with prior processes often takes on the order of twice as long for full bleaching.
  • the various steps of the process are carried out with mild agitation in order to assure intimate contact of the reagents with each other and with the clay.
  • the washing of the treated clay normally is carried out with water, although common aids such as soaps, detergents and the like may be added, and other washing media, for example alcohols, may be used. Separation of the clay from the Temperature, F.:
  • washing liquid is achieved by common means such as filtration, centrifugation, pressing and the like.
  • the clay following sep-aration from the aqueous or other washing may be dried, if desired, at a temperature and pressure which will remove essentially all of the water. In some cases it is desired to use the clay as a slurry, and in such cases the clay will not be dried.
  • Example 1 Preparation of clay samples for bleaching Orude kaolin as obtained from a mine was dispersed in water containing about 0.1% by weight of sodium hexametaphosphate to provide an aqueous slurry containing about 30% by weight of the crude clay. This slurry was stirred in a high speed agitator for 30 minutes, following which it was transferred to a large beaker, the slurry was diluted to provide a 20% solids slurry, and the slurry was allowed to settle for 20 minutes. The suspension which formed was decanted and saved, while the settled material was discarded. The suspension was then allowed to settle for 48 hours, and the precipitated or settled material therefrom was retained for bleaching studies. This material was dried overnight at 100 C. to provide a standard sample of so-called classified clay for use in the following experiments.
  • This classified kaolin clay had a percent reflectance brightness of 83.1% at 458 microns on the GE brightness scale.
  • the instrument employed for this measurement was a Bausch and Lomb 505 Spectronic Spectrophotometer; brightness values presented hereinafter were all determined on this instrument.
  • Example 2 One hundred grams of the classified clay from Example 1 was slurried in 400 g. of water with mild stirring. The pH of the slurry was adjusted to 3.3 with sulfuric acid, and the temperature of the slurry was raised to 120 F. This pH and temperature were maintained throughout the experiment. 0.138 g. of sodium metabisulfite (2.76 pounds per ton of clay) was added to the slurry and dissolved with stirring in a few seconds. 0.025 g. of sodium borohydride (0.50 pound per ton of clay) was then added to the slurry, and the resulting slurry of clay in a solution of the metabisulfite and borohydride was mildly stirred for 30 minutes. The clay was then separated from the bulk of the bleaching solution on a filter and washed with water at room temperature, after which it was dried at C. in an oven.
  • the brightness of the clay prior to the bleaching operation was 83.1%, whereas following bleaching it was 87.9%. This improvement was very noticeable; the naked eye can detect a difference of 0.1% in brightness, and a 0.5% difference is significant in the clay trade.
  • the clay following the bleaching operation had a uniform and low shear viscosity making it highly suitable for use as a paper filler and finishing agent, and as a molding ingredient in the preparation of electrical and other ceramic and plastic products.
  • Example 3 The procedure described in Example 2 was carried out in a series of experiments in which the temperature of the bleach was varied between 70 and 180 F. The results of these experiments are'shown in Table I which follows.
  • the brightness of the clay is dependent upon the temperature at which the bleaching operating is carried out, with optimum brightness being achieved at about 120 F. and the brightness dropping off slightly on either side of this temperature.
  • Operation at 40 F. likewise bleaches the clay to a higher brightness than it was prior to bleaching, as does bleaching at temperatures of200 F.
  • the preferred range of bleaching is about 70 to 180 F.
  • Example 4 The procedure of Example 2 was carried out employing varying concentrations of sodium bisulfite and sodium As demonstrated by this example the amounts of bisulfite and borohydride employed can be varied considerably without destroying the ability of the system to bleach clay effectively.
  • a comparative bleaching operation was carried out with sodium hydrosulfite serving as the bleaching agent. It was employed under the conditions of Example 2 above, with the exception that in place of the sodium metabisulfite and sodium borohydride employed therein, 0.136 g. (2.7 pounds per ton) of sodium hydrosulfite was dissolved in the bleaching liquor.
  • the bleached clay provided by this operation had a. brightness 1.5% below that of the bleached clay from Example 2; the clay of this Example 5 had a brightness of 86.3%. This difference was very noticeable, and was considered by a clay manufacturer to be important in the production of clay for paper finishing and filling agents.
  • Example 6 Substitution of potassium borohydride, lithium borohydride, and magnesium borohydride for the sodium borohydride employed in Example 2 results in the production of bleached clay likewise having excellent brightnesses. The same result is achieved when the sodium metabisulfite and sodium bisulfite of the above examples is replaced with any of the potassium, magnesium or ammonium bisulfites.
  • the process of this invention operates in a short time to provide an excellent brightening of clay. Furthermore, it operates with a readily observable advantage in degree of brightening over a comparative method employing sodium hydrosulfite as the bleaching agent.
  • the improvement in brightness provided by the process of this invention is i ighly significant to clay producers and users; it represents an improvement readily discernible to the eye, and one which is in the area of the best bleach results obtainable heretofore.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Organic Chemistry (AREA)
  • Dispersion Chemistry (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Inorganic Chemistry (AREA)
  • Silicates, Zeolites, And Molecular Sieves (AREA)
  • Detergent Compositions (AREA)
US313763A 1963-10-04 1963-10-04 Clay bleaching Expired - Lifetime US3290161A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US313763A US3290161A (en) 1963-10-04 1963-10-04 Clay bleaching
AT803464A AT248944B (de) 1963-10-04 1964-09-18 Verfahren zur Behandlung von Ton
ES304496A ES304496A1 (es) 1963-10-04 1964-09-29 Método para el blanqueado y refinado de las arcillas
GB40124/64A GB1086718A (en) 1963-10-04 1964-10-02 Improvements in and relating to clay

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Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3399960A (en) * 1966-06-17 1968-09-03 Georgia Kaolin Co Potentiometric control of bleaching of kaolin clays
US3661515A (en) * 1970-05-18 1972-05-09 Huber Corp J M Method of brightening kaolin clay by removing organic contaminants
US3937632A (en) * 1974-06-11 1976-02-10 Anglo-American Clays Corporation Method for brightening and whitening clays utilizing sodium borohydride
EP0027369A1 (de) * 1979-10-12 1981-04-22 Thiokol Corporation Stabile Ausgangslösung zur Herstellung von Hydrosulfit und ihre Verwendung beim Bleichen von Holzschliff, beim Aufhellen von Kaolinton und bei der Reduktion von Küpenfarbstoffen in ihre Leuko-Form
US4919755A (en) * 1987-06-24 1990-04-24 Eka Nobel Ab Process for bleaching
US4935391A (en) * 1989-03-31 1990-06-19 Fmc Corporation Process for preparing a purified mineral coating
US5342443A (en) * 1993-04-06 1994-08-30 Engelhard Corporation Method for bleaching kaolin clay
EP1146089A1 (de) * 2000-04-10 2001-10-17 Rohm And Haas Company Verfahren zum Bleichen von Kaolin Ton und anderen Mineralien und erhaltene, gebleichte Produkte
US20080052838A1 (en) * 2006-09-01 2008-03-06 Qiang Huang Method for leaching and brightening kaolin clay and other minerals
WO2010049591A1 (en) * 2008-10-31 2010-05-06 Kemira Oyj Bleaching method
US20110232904A1 (en) * 2010-03-25 2011-09-29 Montgomery Chemicals, Llc Method and composition for oil enhanced recovery
WO2013186416A2 (es) 2012-06-11 2013-12-19 Nanobiomatters Research & Development, S.L. Materiales activos basados en cerio con capacidad catalítica y procedimiento para su obtención

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB242358A (en) * 1924-08-07 1925-11-09 William Feldenheimer Improvements in or relating to processes for improving the colour of clays
US1588956A (en) * 1924-08-07 1926-06-15 Feldenheimer William Treatment of clay

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB242358A (en) * 1924-08-07 1925-11-09 William Feldenheimer Improvements in or relating to processes for improving the colour of clays
US1588956A (en) * 1924-08-07 1926-06-15 Feldenheimer William Treatment of clay

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3399960A (en) * 1966-06-17 1968-09-03 Georgia Kaolin Co Potentiometric control of bleaching of kaolin clays
US3661515A (en) * 1970-05-18 1972-05-09 Huber Corp J M Method of brightening kaolin clay by removing organic contaminants
US3937632A (en) * 1974-06-11 1976-02-10 Anglo-American Clays Corporation Method for brightening and whitening clays utilizing sodium borohydride
EP0027369A1 (de) * 1979-10-12 1981-04-22 Thiokol Corporation Stabile Ausgangslösung zur Herstellung von Hydrosulfit und ihre Verwendung beim Bleichen von Holzschliff, beim Aufhellen von Kaolinton und bei der Reduktion von Küpenfarbstoffen in ihre Leuko-Form
US4919755A (en) * 1987-06-24 1990-04-24 Eka Nobel Ab Process for bleaching
US4935391A (en) * 1989-03-31 1990-06-19 Fmc Corporation Process for preparing a purified mineral coating
US5342443A (en) * 1993-04-06 1994-08-30 Engelhard Corporation Method for bleaching kaolin clay
EP1146089A1 (de) * 2000-04-10 2001-10-17 Rohm And Haas Company Verfahren zum Bleichen von Kaolin Ton und anderen Mineralien und erhaltene, gebleichte Produkte
US20080052838A1 (en) * 2006-09-01 2008-03-06 Qiang Huang Method for leaching and brightening kaolin clay and other minerals
WO2010049591A1 (en) * 2008-10-31 2010-05-06 Kemira Oyj Bleaching method
US20110203485A1 (en) * 2008-10-31 2011-08-25 Kemira Oyj Bleaching method
EP2344695A4 (de) * 2008-10-31 2013-09-11 Kemira Oyj Bleichverfahren
US20110232904A1 (en) * 2010-03-25 2011-09-29 Montgomery Chemicals, Llc Method and composition for oil enhanced recovery
US8662171B2 (en) * 2010-03-25 2014-03-04 Montgomery Chemicals, Llc Method and composition for oil enhanced recovery
WO2013186416A2 (es) 2012-06-11 2013-12-19 Nanobiomatters Research & Development, S.L. Materiales activos basados en cerio con capacidad catalítica y procedimiento para su obtención

Also Published As

Publication number Publication date
GB1086718A (en) 1967-10-11
ES304496A1 (es) 1964-11-16
AT248944B (de) 1966-08-25

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