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
  • C01F11/18—Carbonates
  • C01F11/182—Preparation of calcium carbonate by carbonation of aqueous solutions and characterised by an additive other than CaCO3-seeds
  • C01F11/183—Preparation of calcium carbonate by carbonation of aqueous solutions and characterised by an additive other than CaCO3-seeds the additive being an organic compound
• • 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
  • C01F11/18—Carbonates
  • C01F11/181—Preparation of calcium carbonate by carbonation of aqueous solutions and characterised by control of the carbonation conditions
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/01—Particle morphology depicted by an image
  • C01P2004/03—Particle morphology depicted by an image obtained by SEM
• • 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
  • C01P2004/00—Particle morphology
  • C01P2004/60—Particles characterised by their size
  • C01P2004/62—Submicrometer sized, i.e. from 0.1-1 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
  • C01P2006/12—Surface area
• • 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
  • C01P2006/80—Compositional purity

Definitions

• the present invention relates to a process and a product produced using the process.
• the product is discrete particles of calcium carbonate having an average particle size, a specific surface area and high purity.
• the method for preparing the discrete calcium carbonate particles of the present invention requires carbonating an aqueous calcium hydroxide slurry in the presence of carbohydrates, while varying the selected starting carbonation temperature, and/or the concentration of the carbohydrates.
• PCC is traditionally prepared by carbonating an aqueous calcium hydroxide slurry with a carbon dioxide gas to obtain calcium carbonate particles.
• the traditional process for the production of PCC is quite adequate for particles that do not require discreteness.
• there are problems with the traditional method for producing PCC where discreteness of the final particle is required.
• U.S. Patent No. 5,332,564 discloses a process for producing rhombic or barrel shaped PCC comprising slaking quicklime in an aqueous sugar solution to form a slaked lime slurry, carbonating the slaked lime slurry with carbon dioxide containing gas until rhombic shape calcium carbonate is precipitated.
• J.P. 9-271,313 discloses a method for using inexpensive low grade furnace gas (CO 2 ) to make a spindle shaped Precipitated Calcium Carbonate at 50°C to 65°C. The method depends on the mesh size of the lime to control particle size and no additives are used. After viewing the related art, there continues to be a need for a novel method for producing discrete calcium carbonate.
• CO 2 inexpensive low grade furnace gas
• Fig. 1 Shows the prior art scalenohedral form of calcite
• Fig. 2 Shows the prior art rhombohedral form of calcite
• Fig. 3 Shows the prior art aragonite
• Fig. 6 Represents still a further magnified view of the novel discrete calcite crystals of the present invention.
• Discrete as used herein, means that the particles are generally distinct and unconnected.
• a preferred particle is scalenhodral and has an aspect ratio, which compares length/width (1/w), averages about 2.0 or more.
• carbon dioxide containing gas is not a particularly critical aspect of the present invention. Pure carbon dioxide gas may be employed or standard mixtures of carbon dioxide in either air, or nitrogen, may also be used in the method of the present invention. Liquid carbon dioxide, as well, can be used in accordance with the product and process of the present invention, by introducing the liquid carbon dioxide in its gaseous state during the carbonation process step.
• discrete calcium carbonate particles of the present invention it was found that while maintaining the selected starting carbonation temperature, and while maintaining the level of carbohydrates constant, discrete calcium carbonate particles were produced from different limes.
• the particles were characterized as having an average particle size of from about 0J microns to about 3.0 microns and specific surface areas of from about 2 square meters per gram to about 60 square meters per gram.
• the carbonation of the aqueous lime slurry by the introduction of the carbon dioxide is continued until calcite precipitation is substantially complete.
• the carbonation process is preferably complete when the pH of the carbonated slurry is about neutral, seven(7), and the calcium carbonate particle has a purity of about ninety-eight(98) percent calcium carbonate.
• a Micromeritics FLOWSORB II 2300 which employed the BET theory with nitrogen as the adsorbing gas, can be used to determine surface area.
• Example 1 A cylindrical stainless steel reactor having a hemispherical bottom, equipped with a high-speed agitator driven by a 1/15 hp variable speed motor, and a stainless steel tube curved under the center of the bottom blade for the introduction of a carbon dioxide/air stream, was used for preparation and reaction of calcium hydroxide (slake) to make the present invention.
• a 14.2% weight percent (0J54 g/cc) aqueous calcium hydroxide slurry was prepared by adding 250g of granular Bellefonte lime; having an available calcium oxide content of 94 or greater weight percent as determined by ASTM procedure C-25-72, to 2000 ml of water in the 4-liter reactor at 50°C and stirred at 1100 RPM for ten minutes.
• the slurry was screened through a 60 mesh sieve to remove grit and heated to a starting carbonation temperature of 55°C.
• the agitator was adjusted to 1250 RPM and 0.5% Domino Sugar, manufactured by Domino Sugar Corporation, hereinafter referred to as sucrose by weight of calcium carbonate equivalent of the available lime as added to the slurry.
• the slurry was carbonated to precipitate calcium carbonate by introducing a gas mixture of 10% carbon dioxide in air at 0.45 SLM into the slurry. The carbonation was continued for 263 minutes until the pH value was less than 8.0.
• the slurry was passed through US Standard No. 325 (44 microns) sieve to remove grit.
• Example 2 Three additional samples were synthesized at different starting carbonation temperatures, i.e. 60°C, 65°C and 70°C. The data from Examples 1-4 are compared in Table 1.
• Example 5 Three additional samples were synthesized at different starting carbonation temperatures, i.e. 60°C, 65°C and 70°C. The data from Examples 1-4 are compared in Table 1.
• Example 5 Three additional samples were synthesized at different starting carbonation temperatures, i.e. 60°C, 65°C and 70°C. The data from Examples 1-4 are compared in Table 1.
• Example 5 Three additional samples were synthesized at different starting carbonation temperatures, i.e. 60°C, 65°C and 70°C. The data from Examples 1-4 are compared in Table 1.
• Example 5 Three additional samples were synthesized at different starting carbonation temperatures, i.e. 60°C, 65°C and 70°C. The data from Examples 1-4 are compared in Table 1.
• Example 5 Three additional samples were synthesized at different starting carbonation temperatures, i.
• Example 5 was prepared after the fashion of Example 1 using the same lime but with the following changes.
• the calcium hydroxide slurry concentration was 10.7% (0J 14 g/cc) instead of 14J weight percent.
• the sucrose addition was again 0.5% but the gas consisted of 18% CO,, rather than 10% CO 2 .
• the CO 2 rate was 1.75 SLM providing a reaction time of 63 minutes to a pH of 8.0.
• the initial reaction temperature was 60°C.
• the product was screened through U.S. Standard No. 325 (44 microns) sieve to remove grit.
• the product had an average particle size of 1 J0 microns and had a specific surface area (SSA) of 10.4 m 2 /g. This experiment is identified as Example 5 in Table 1.
• SSA specific surface area
• Example 1 through 4 exhibit the effect of temperature on particle size while maintaining the sucrose level constant. As the temperature rises, the particle size increases and the specific surface area declines.
• a 15.7 weight percent (0J692 g/cc) aqueous calcium hydroxide slurry was prepared by adding 3000g of Bellefonte lime to 18.0 liters of water in the above described 70 gallon mortar mixer, at 50°C and stirred for 10 minutes. The slurry was screened through a 60 mesh sieve to remove grit and heated in the reactor to a starting carbonation temperature of 45°C. The agitator was adjusted to 615 RPM and 0J5 percent sucrose by weight, based on the calcium carbonate equivalent of the available lime, was added to the slurry.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Health & Medical Sciences (AREA)
• General Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Geology (AREA)
• Inorganic Chemistry (AREA)
• Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)

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• 1999
  • 1999-03-31 KR KR1020017012199A patent/KR20020023213A/ko active IP Right Grant
  • 1999-03-31 AU AU33697/99A patent/AU3369799A/en not_active Abandoned
  • 1999-03-31 WO PCT/US1999/006853 patent/WO2000058217A1/en active IP Right Grant
  • 1999-03-31 PL PL350921A patent/PL192346B1/pl not_active IP Right Cessation
  • 1999-03-31 RU RU2001129290/12A patent/RU2215692C2/ru active
  • 1999-03-31 CA CA002368174A patent/CA2368174C/en not_active Expired - Fee Related
  • 1999-03-31 SK SK1351-2001A patent/SK13512001A3/sk not_active Application Discontinuation
  • 1999-03-31 JP JP2000607929A patent/JP2002540056A/ja active Pending
  • 1999-03-31 CN CN99816536A patent/CN1348428A/zh active Pending
  • 1999-03-31 IL IL14512699A patent/IL145126A/xx not_active IP Right Cessation
  • 1999-03-31 BR BR9917234-8A patent/BR9917234A/pt not_active Application Discontinuation
  • 1999-03-31 EP EP99915098A patent/EP1165441A1/en not_active Withdrawn
• 2001
  • 2001-09-25 ZA ZA200107865A patent/ZA200107865B/xx unknown
  • 2001-09-25 NO NO20014652A patent/NO20014652D0/no not_active Application Discontinuation
• 2002
  • 2002-09-26 HK HK02107051.9A patent/HK1045493A1/zh unknown

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