Omya International Ag

Coatex

Mathieu Skrzypczak

Marc Maurer

Joe Wenk

Holger Spiegel

Patrick A C Gane

Catherine Jean Ridgway

George Saunders

Thomas Schmölzer

Wolfgang Kreuger

Thomas Schlotterbach

Michael Dalton

Robert Pirker

Aaro Salonen

Christian Jacquemet

Luis Pedroso

The present invention is directed to a process for producing precipitated calcium carbonate with improved resistance to structural breakdown, wherein the milk of lime is carbonated in the presence of at least one gas other than carbon dioxide, or the carbonation is carried out in the presence of a static gas bubble comminution unit as well as to precipitated calcium carbonate obtained by such a process.

Precipitated calcium carbonate with improved resistance to structural breakdown

The present invention relates to a process for the preparation of precipitated calcium carbonate allowing for a more sustainable and cost-efficient use of milk of lime. The obtainable products show good optical properties as well as fine particle size distributions.

Process for the production of precipitated calcium carbonate

The present invention provides a process for preparing a precipitated calcium carbonate product comprising the steps of: (a) preparing an aqueous suspension of precipitated calcium carbonate seeds by carbonating a suspension of Ca(OH)in the presence of 0.005 to 0.030 moles of Sr, in the form of Sr(OH), per mole of Ca(OH), (b) dewatering and dispersing the precipitated calcium carbonate seeds prepared in step (a) to obtain an aqueous suspension of precipitated calcium carbonate seeds having a dof less than or equal to 0.1 to 0.3 &#x3bc;m and a BET specific surface area of 10 to 30 m/g, and (c) forming an aqueous suspension of a precipitated calcium carbonate product by carbonating a slurry of Ca(OH)in the presence of 0.5 to 5% by dry weight of the precipitated calcium carbonate seeds obtained in step (b), wherein the precipitated calcium carbonate seeds have a dthat is less than the dof the precipitated calcium carbonate product and the precipitated calcium carbonate seeds have an aragonitic polymorph content greater than or equal to the precipitated calcium carbonate product obtained in step (c) characterized in that the dewatering of step (b) is carried out by the use of a tube press.

Process for obtaining precipitated calcium carbonate

The present invention is directed to a process for producing an aqueous suspension of precipitated calcium carbonate, wherein a milk of lime is prepared by mixing water, a calcium oxide containing material, at least one water-soluble polymer having a molecular weight Min the range from 200 to 6500 g/mol, and at least one slaking additive, and subsequently, the milk of lime is carbonated to form an aqueous suspension of precipitated calcium carbonate.

Production of PCC

The present invention provides a process for preparing a precipitated calcium carbonate product. The process comprises the steps of preparing slaking quick lime to obtain slaked lime; and subjecting the slaked lime, without agitation, without prior cooling in a heat exchanger, and in the absence of any additives, to carbonation with carbon dioxide gas to produce PCC. The newly prepared product develops better performance thanks to improved resistance during processing.

Process for preparing scalenohedral precipitated calcium carbonate

The present invention provides a process for preparing a precipitated calcium carbonate product. The process comprises the steps of preparing slaking quick time to obtain slaked lime; and subjecting the slaked lime, without agitation, without prior cooling in a heat exchanger, and in the absence of any additives, to carbonation with carbon dioxide as to produce PCC. The newly prepared product develops better performance thanks to improved resistance during processing.

The present invention relates to a process for the production of precipitated calcium carbonate, comprising the following steps: a) providing a reaction vessel containing an aqueous phase at an initial temperature; b) injecting a carbon dioxide generating compound into the aqueous phase until the pH of the aqueous phase is in the range of around 5 to around 7; and c) subsequently adding a calcium hydroxide slurry at an initial temperature to the reaction vessel while continuing the injection of the carbon dioxide generating compound, in order to obtain an aqueous slurry of the precipitated calcium carbonate. The addition rate of the calcium hydroxide slurry to the reaction vessel in step c) is such that an average electrical conductivity of the reaction contents in the reaction vessel during the reaction is in a range of 100 to 6,000 &#x3bc;S/cm.

Process for the production of precipitated calcium carbonate, precipitated calcium carbonate and uses thereof

The present invention relates to a process for the production of precipitated calcium carbonate, comprising the following steps: a) providing a reaction vessel containing an aqueous phase at an initial temperature; b) injecting a carbon dioxide generating compound into the aqueous phase until the pH of the aqueous phase is in the range of around 5 to around 7; and c) subsequently adding a calcium hydroxide slurry at an initial temperature to the reaction vessel while continuing the injection of the carbon dioxide generating compound, in order to obtain an aqueous slurry of the precipitated calcium carbonate. The addition rate of the calcium hydroxide slurry to the reaction vessel in step c) is such that an average electrical conductivity of the reaction contents in the reaction vessel during the reaction is in a range of 100 to 6 000 &#x3bc;S/cm.

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Terrace Park, OH, United States of America

Mathieu Skrzypczak