Defluorination Patents (Class 71/DIG3)
  • Patent number: 4423015
    Abstract: In a process for producing a defluorinated product containing calcium, sodium and phosphorus, by calcination of a mixture of phosphate rock, with caustic soda, phosphoric acid and water, an improvement comprises maintaining the amount of phosphoric acid in the mixture such that the ratio of phosphorus in percentage by weight on a dry basis in said mixture-to-the phosphorus desired in percentage by weight in the calcined product is substantially equivalent to the ratio of the calcium in percentage by weight on a dry basis in the mixture-to-the calcium in percentage by weight in the calcined product. The process is especially useful where the phosphate rock has a bone phosphate of lime analysis of about 73% or less (e.g., about 71.5%), and also where the caustic soda is added to a mixture of phosphate rock and phosphoric acid prior to the addition of water.
    Type: Grant
    Filed: February 4, 1982
    Date of Patent: December 27, 1983
    Assignee: Occidental Chemical Company
    Inventors: John W. Roy, Jr., Melvin J. Arbie, Joel P. Holmes
  • Patent number: 4405575
    Abstract: This invention comprises a method for removing fluorine from natural phosphates, superphosphate materials and wet process phosphoric acids starting materials comprising(a) admixing rock phosphate having a fluorine content above that desired with an acid mixture within the range of rock:acid mixture of about 0.8 to 1 and 1:1.4 by weight;(b) said acid mixture being substantially concentrated phosphoric acid and concentrated sulfuric acid in a range of phosphoric:sulfuric of about 1:1 to 5:1 by weight;(c) said admixing being at a temperature in the range of to F. while adding water in an amount of up to about 12% by weight of the total mixture and then subjecting the above charge;(d) in a first heating stage adding (1) recycle in an amount substantially of recycle to charge of 1:1 to 10:1 by weight (2) and water while heating to a temperature in the range of F. to F.
    Type: Grant
    Filed: April 23, 1982
    Date of Patent: September 20, 1983
    Inventor: Albert E. Henderson
  • Patent number: 4205049
    Abstract: An improved process is described for preparing defluorinated phosphate rock (DPR) granules from fluorine-containing phosphate rock.
    Type: Grant
    Filed: May 31, 1977
    Date of Patent: May 27, 1980
    Assignee: Olin Corporation
    Inventors: Ronald J. Smith, Manuel A. Gonzalez
  • Patent number: 4175944
    Abstract: The invention provides a novel process for the removal of fluorine during the production of fertilizer by precipitating the ion during the ammoniation step and recovering same by pyrolysis.To recover the fluorine the fertilizer is first separated out as a filtrate and the precipitate is heated to evolve ammonium fluoride, which heating is done in an ammonia atmosphere.
    Type: Grant
    Filed: June 26, 1978
    Date of Patent: November 27, 1979
    Assignee: Mobil Oil Corporation
    Inventor: George C. Johnson
  • Patent number: 4160657
    Abstract: Monocalcium phosphate, phosphoric acid and/or potassium phosphate containing fertilizers are produced in a process involving acidulation of phosphate rock with phophoric acid in the presence of added silicon dioxide and potassium ion whereby fluorides contained in the rock are converted to K.sub.2 SiF.sub.6, wherein monocalcium phosphate dissolved in phosphoric acid is formed during acidulation. In an important feature, the K.sub.2 SiF.sub.6 is separated and hydrolyzed to regenerate the K.sub.2 O from K.sub.2 SiF.sub.6 as recycled KH.sub.2 PO.sub.4 /H.sub.3 PO.sub.4 solution for further reaction with fluoride from fresh phosphate rock feed. A portion of the MCP/H.sub.3 PO.sub.4 solution and/or crystallized monocalcium phosphate can then be reacted with potassium sulfate, potassium bisulfate, or mixtures thereof, to form KH.sub.2 PO.sub.4, or KH.sub.2 PO.sub.4 /H.sub.3 PO.sub.4 solutions, and gypsum. In a closely related embodiment, the remaining MCP/H.sub.3 PO.sub.
    Type: Grant
    Filed: August 2, 1978
    Date of Patent: July 10, 1979
    Assignee: Pennzoil Company
    Inventor: Erhart K. Drechsel
  • Patent number: 4152398
    Abstract: An improved process is described for preparing defluorinated phosphate rock (DPR) granules useful as animal feed from fluorine-containing phosphate rock.
    Type: Grant
    Filed: June 9, 1977
    Date of Patent: May 1, 1979
    Assignee: Olin Corporation
    Inventor: Harold V. Larson
  • Patent number: 4106922
    Abstract: A process for the production of highly citrate-soluble calcined phosphate fertilizers is disclosed. The process comprises calcinating a mixture which comprises appropriate amounts of calcium phosphates, silicic acid and an alkaline decomposing agent whereby the naturally occurring mineral trona is used as an alkaline decomposing agent. The process is effected in a rotary kiln; the maximum temperature is about C.
    Type: Grant
    Filed: February 18, 1977
    Date of Patent: August 15, 1978
    Assignee: Kali-Chemie
    Inventors: Ulrich Hauschild, Heinrich Roetger
  • Patent number: 4101636
    Abstract: An improved process is described for preparing defluorinated phosphate rock from fluorine-containing phosphate rock which contains acid insoluble impurities in excess of about 6 percent by weight. The improvement is particularly useful in the fluidized bed technique for preparing defluorinated phosphate rock wherein fluorine-containing phosphate rock, a sodium compound such as sodium carbonate, phosphoric acid and water are admixed to form granules. The resulting granules are dried and heated in a fluidized bed calciner at a temperature within the range of from about to about 1, C to evolve sufficient fluorine to produce defluorinated phosphate rock graules having less than 1 part of fluorine per 100 parts of phosphorus by weight. The resulting defluorinated granules are colled and stored for use as an animal feed which contains at least 18 percent by weight of phosphorus.
    Type: Grant
    Filed: January 21, 1977
    Date of Patent: July 18, 1978
    Assignee: Olin Corporation
    Inventors: Harold V. Larson, Morris E. Clark
  • Patent number: 4043789
    Abstract: The invention relates to a process for the production of phosphoric acid containing calcium phosphates, i.e. Ca-containing phosphoric acid, by evaporating Ca-containing mother liquor from Odda process, whereby practically all the remaining nitrate and fluorine are removed in the form of HNO.sub.3, HF and SiF.sub.4, in which process the Ca-containing mother liquor is given a Ca/P weight ratio which is lower than 0.45 and is evaporated while recycling Ca-containing phosphoric acid, the recirculation being so controlled that the liquor has a phosphorus concentration during evaporation which is always adequate to prevent the liquor from forming a paste-like mass. Thus, it was discovered that the undesirable paste-like consistency experienced when calcium is present during evaporation can be avoided by controlling the phosphorus content.
    Type: Grant
    Filed: March 19, 1975
    Date of Patent: August 23, 1977
    Assignee: Norsk Hydro a.s
    Inventors: Rolf Steen Hansen, Ole Hannibal Lie, Henning Reier Nilsen, Thor Sandal
  • Patent number: T982001
    Abstract: a method for improving the storage properties of liquid fertilizers made from wet-process phosphoric acid. The wet-process acid is essentially defluorinated so that when it is processed by ammoniation to make high-analysis ammonium polyphosphate liquid fertilizers, the sometimes almost immediate precipitation of undesirable sludge compounds of magnesium does not occur in the liquid over long periods of storage. The liquids may be produced by dissolving hot ammonium polyphosphate melts directly as it is produced or by dissolving dry granular solid ammonium polyphosphate made from this type acid.Both ammonium polyphosphate and urea-ammonium polyphosphate base solutions made from defluorinated wet-process acid are highly stable and they exhibit increased tolerance for higher magnesium and lower polyphosphate levels.
    Type: Grant
    Filed: March 16, 1977
    Date of Patent: May 1, 1979
    Assignee: Tennessee Valley Authority
    Inventor: Fred D. Nix