EP0096075A1 - Conversion de fluoroanhydrite en platre - Google Patents

Conversion de fluoroanhydrite en platre

Info

Publication number
EP0096075A1
EP0096075A1 EP83900397A EP83900397A EP0096075A1 EP 0096075 A1 EP0096075 A1 EP 0096075A1 EP 83900397 A EP83900397 A EP 83900397A EP 83900397 A EP83900397 A EP 83900397A EP 0096075 A1 EP0096075 A1 EP 0096075A1
Authority
EP
European Patent Office
Prior art keywords
fluoroanhydrite
fluorogypsum
gypsum
water
calcium sulfate
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP83900397A
Other languages
German (de)
English (en)
Other versions
EP0096075A4 (fr
Inventor
Robert Byron Bruce
John C. Gaynor
Jay W. Palmer
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
United States Gypsum Co
Original Assignee
United States Gypsum Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by United States Gypsum Co filed Critical United States Gypsum Co
Publication of EP0096075A1 publication Critical patent/EP0096075A1/fr
Publication of EP0096075A4 publication Critical patent/EP0096075A4/fr
Withdrawn legal-status Critical Current

Links

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
    • C01F11/00—Compounds of calcium, strontium, or barium
    • C01F11/46—Sulfates
    • C01F11/466—Conversion of one form of calcium sulfate to another
    • 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
    • C04B11/00—Calcium sulfate cements
    • C04B11/02—Methods and apparatus for dehydrating gypsum
    • C04B11/024—Ingredients added before, or during, the calcining process, e.g. calcination modifiers
    • 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
    • C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
    • C04B14/02—Granular materials, e.g. microballoons
    • C04B14/04—Silica-rich materials; Silicates

Definitions

  • This invention relates to a process for transforming fluoroanhydrite into gypsum plaster and gypsum wallboard products.
  • Fl ⁇ ororanhydrite is a by-product in the manufacture of hydrogen fluoride from the sulfuric acid treatment of fluorite (calcium fluoride).
  • fluorite calcium fluoride
  • the fluoroanhydrite which is contaminated with sulfuric acid, is neutralized with lime or calcium carbonate additions and allowed to hydrate naturally over a several year period of time while weathering in waste heaps. It had been hoped that upon weathering such materials would then be usable in the industrial manufacture of various products. This has not proven to be the case. Description of the Prior Art
  • fluoroanhydrite contains other impurities.
  • Fluoroanhydrite or fluorogypsum can contain up to 2-3% fluoride, probably derived from unreacted calcium fluoride, together with smaller quantities of unreacted soluble and insoluble silicofluorides.
  • fluorine impurity species probably a fluoroaluminum complex anion such as [AlF-H 2 O -2 ] impede the practical commercial conversion of the stockpiled material into calcium sulfate hemihydrate.
  • these impurities inhibit the hydration
  • a part of the findings of the present invention is that while some of the fluorine and aluminum species contamination in by-product fluoroanhydrite can bo removed by careful washing during the various conversion stages, complex species are trapped in the growing calcium sulfate crystal. By including reactive silicates during various stages of the processing, the crystallized species can either be inhibited in their growth and/or removed from the calcium sulfate crystals.
  • the starting material is a residue from the process of manufacturing hydrofluoric acid from fluorospar.
  • Fluoroanhydrite fresh from the reactor may be treated by the process of this invention and then stored for gradual conversion.
  • weathered stockpile material containing fluorogypsum as well as fluoroanhydrite may be treated.
  • treatment may be carried out during calcination of the fluorogypsum to fluorostucco.
  • hot fluoroanhydrite directly from the reactor may be blended with the reactive siliceous material and passed to briquetting or pelletizing apparatus for mixing with a suitable binder while being formed into briquettes or pellets.
  • the briquettes may then be warehoused or stockpiled while the conversion to fluorogypsum occurs. Thereafter, the fluorogypsum is calcined to fluorostucco for use as plaster products or subsequent rehydration in gypsum board manufacture.
  • Suitable active siliceous materials preferably include Portland cement, finely ground expanded perlite, diatomaceous earth, reactive colloidal silica such as Cab-O-Sil® silica or Aerosil® fumed pyrogenic silica and alkaline earth metal silicates such as sodium, potassium and calcium silicate. These are all siliceous products having high surface areas (greater than about 10,000 square centimeters per gram) and having chemically reactive sites due to surface deformaties, such as chemically incomplete silicon dioxide surfaces, missing oxygen atoms in the alkali metal silicates and Portland cement, or stressed crystal configurations in expanded perlite sintered or fumed silicas and diatomaceous earth. Other reactive siliceous products suitable for use in this invention will be evident from this description.
  • siliceous material Generally inclusion of about 1-10% by weight of the active siliceous material based on the weight of calcium sulfate present in the fluoroanhydrite will produce satisfactory results. Preferred amounts of siliceous material are dependent upon the time at which the material is added in the process and the particular siliceous material.
  • the difficult contaminant species are co-crystalline or occluded, i.e., as the fluoroanhydrite is undergoing the transformation to fluorogypsum, contaminant ions in the surrounding solution crystallize on the growing gypsum phase and are occluded or co-crystallized in the gypsum matrix. It has now been found that these contaminating ions can be rendered inactive in the solution phase, and then the gypsum which re-crystallizes is relatively free of impurities and has properties similar to those of natural gypsum.
  • the preferred first step for fresh or weathered fluoroanhydrite material is a water or dilute acid wash.
  • washing the weathered material twice with water, with a light grinding in between washings drammatically increased the surface area from about 6,000 cm 2 /g to 15,900 cm 2 /g; and reduces the set time with a standard amount of accelerator from approximately 12 minutes without washing to 6.3 minutes after the double washing.
  • the light grinding and second wash released some of the impurities.
  • the same treatment steps using 32% sulfuric acid instead of water gave an even better accelerated set time response of 4 minutes.
  • neither of these treatments provided sufficient strength or the dispersion disintegration characteristics of natural gypsum.
  • active siliceous materials may be added to the mixing (gauging) water of fluorostucco.
  • the following were evaluated as slurry additives to fluorostucco obtained by calcining different weathered fluorogypsum samples without any adjustments. The samples were from different locations in the fluorogypsum pile and analysis indicated widely varying degrees of hydration and chemicals content:
  • active siliceous materials may be added to the fluorogypsum at the stage of calcination to fluorostucco.
  • the additives were mixed with weathered fluorogypsum and then kettle calcined under standard conditions. Since kettle calcination itself is a topatactic dehydration, the additives at this point should have a surface effect rather than a crystallographic effect.
  • the difficult-to-remove contaminant species are co-crystalline.
  • the fluoroanhydrite is undergoing the transformation to fluorogypsum, contaminant ions in the surrounding solution crystallize on the growing gypsum phase and are occluded in the gypsum matrix.
  • the high drag temperature of the fluorogypsum demonstrates the adverse effect of even low concentrations of the impurities in the gypsum lattice.
  • the impurity species probably a fluoroaluminum ion complex such as [A1F 5 (H 2 O)] -2 , desensitizes the calcined fluorostucco to the presence of accelerators in the mixing water.
  • Fluoroanhydrate Hydration Additive The additives listed below were mixed with fluoroanhydrite and neutralized gypsum pond water and allowed to weather hydrate over time. When the samples had hydrated to an appreciable extent above 70% gypsum they were kettle calcined without further additive addition to fluorostucco and the Vicat and temperature rise set times of the materials with and without 10 pounds per ton setting accelerator and gauging water without further additive addition were determined:

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Organic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Civil Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Inorganic Chemistry (AREA)
  • Curing Cements, Concrete, And Artificial Stone (AREA)
  • Glass Compositions (AREA)

Abstract

Du plâtre de gypse et des produits de plaque de paroi en gypse peuvent être fabriqués à partir de fluoroanhydrite en mettant en contact le fluoroanhydrite avec une silice réactive sélectionnée parmi le groupe comprenant essentiellement le ciment Portland, la perlite, le calcium, le silicate de sodium ou le silicate de potassium, la silice colloïdale pyrogénée et les terres de diatomées; après conversion progressive du fluoroanhydrite en fluorogypse sensiblement pur, le gypse purifié est traité de manière conventionnelle dans la fabrication industrielle de produits en plâtre. La silice réactive peut être ajoutée au fluoroanhydrite soit pendant la conversion graduelle par vieillissement dans l'eau en fluorogypse, soit pendant l'hydrocalcination du fluorogypse en stuc, soit à l'eau de jaugeage pendant la formation de produit de plaque de paroi ou de plâtre de gypse à partir du fluorostuc.
EP19830900397 1981-12-21 1982-12-21 Conversion de fluoroanhydrite en platre. Withdrawn EP0096075A4 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US33257981A 1981-12-21 1981-12-21
US332579 1981-12-21

Publications (2)

Publication Number Publication Date
EP0096075A1 true EP0096075A1 (fr) 1983-12-21
EP0096075A4 EP0096075A4 (fr) 1984-06-13

Family

ID=23298864

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19830900397 Withdrawn EP0096075A4 (fr) 1981-12-21 1982-12-21 Conversion de fluoroanhydrite en platre.

Country Status (3)

Country Link
EP (1) EP0096075A4 (fr)
AU (1) AU1150583A (fr)
WO (1) WO1983002266A1 (fr)

Family Cites Families (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA590594A (en) * 1960-01-12 Calligaris Giuseppe Process for de-acidifying anhydrous gypsum produced from fluorspar
US1756637A (en) * 1927-04-09 1930-04-29 Rumford Chemical Works Method of preparing by-product calcium sulphate for plaster
US1969449A (en) * 1931-10-17 1934-08-07 Rumford Chemical Works Process of producing by-product calcium sulphate
US2606127A (en) * 1949-03-25 1952-08-05 Weber Herman Light-weight building materials and their manufacture from synthetic anhydrous calcium sulfate
US3042537A (en) * 1961-06-23 1962-07-03 W J Newell Gypsum plaster
GB983204A (en) * 1962-05-26 1965-02-10 Bayer Ag A process for the neutralisation of calcium sulphate containing hydrofluoric acid and sulphuric acid
AT273042B (de) * 1967-04-07 1969-07-25 Chemie Linz Ag Verfahren zur Entfernung von Fluor und Phosphat aus Phosphorsäurefällungsgips
GB1248037A (en) * 1968-01-13 1971-09-29 Fisons Ltd Calcium sulphate
US3847634A (en) * 1973-03-12 1974-11-12 R Vickery Synthetic lightweight building material
AT346223B (de) * 1974-12-11 1978-10-25 Chemie Linz Ag Verfahren zur gewinnung von fluorarmem gips als abfallprodukt aus dem nassphosphorsaeureverfahren
AT345251B (de) * 1976-05-31 1978-09-11 Chemie Linz Ag Verfahren zur herstellung von fluorarmem calciumsulfat
JPS5941938B2 (ja) * 1976-12-02 1984-10-11 日産化学工業株式会社 石膏スラリ−のフロ−値向上方法

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
No relevant documents have been disclosed *
See also references of WO8302266A1 *

Also Published As

Publication number Publication date
EP0096075A4 (fr) 1984-06-13
WO1983002266A1 (fr) 1983-07-07
AU1150583A (en) 1983-07-15

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PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

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Effective date: 19840105

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18D Application deemed to be withdrawn

Effective date: 19860701

RIN1 Information on inventor provided before grant (corrected)

Inventor name: PALMER, JAY W.

Inventor name: BRUCE, ROBERT BYRON

Inventor name: GAYNOR, JOHN C.