Process for the produciton of synthetic magnesium silicate compositons
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Abstract
A method for the preparation of a synthetic magnesium silicate having a crystal structure similar to natural hectorite, includes the steps of a) forming a precursor slurry, b) subjecting the precursor slurry to a continuous hydrothermal reaction in a pipe reactor at a temperature of from 210° C. to 400° C. and under a pressure of at least 20 10 bar for 10 seconds to 4 hours, and e) washing and filtering to remove water soluble salts formed in the preparation of the precursor slurry. The precursor slurry is not washed and filtered before it is subjected to the continuous hydrothermal reaction.
95 Citations
56 Claims
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1-36. -36. (canceled)
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37. A method for preparing a synthetic magnesium silicate having a crystal structure similar to natural hectorite;
- the method comprising;
forming a precursor slurry;
subjecting the precursor slurry to a continuous hydrothermal reaction in a pipe reactor at a temperature ranging from 210°
C. to 400°
C. and under a pressure of at least 20 bar for 10 seconds to 4 hours to form the synthetic magnesium silicate, wherein the precursor slurry is not washed and filtered before it is subjected to the continuous hydrothermal reaction; and
washing and filtering the synthetic magnesium silicate to remove water soluble salts formed in the preparation of the precursor slurry. - View Dependent Claims (38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50)
- the method comprising;
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51. A synthetic magnesium silicate prepared by a method comprising:
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preparing a precursor slurry comprising a magnesium compound and silica;
subjecting the precursor slurry to a continuous hydrothermal reaction in a pipe reactor at a temperature ranging from 210°
C. to 400°
C. and at a pressure of at least 20 bar for 10 seconds to 4 hours to form the synthetic magnesium silicate, wherein the precursor slurry is not washed and filtered before it is subjected to the continuous hydrothermal reaction; and
washing and filtering the synthetic magnesium silicate to remove water soluble salts formed in the preparation of the precursor slurry. - View Dependent Claims (52, 53, 54, 55)
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56. A synthetic magnesium silicate of a general formula:
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[Si8(MgaLibHc)O20(OH)4-yFy]z−
.zM+ where a ranges from 4.9 to 5.7;
b ranges from 0 to 1.05;
c ranges from 0 to less than 2;
(a+b+c) ranges from 5 to less than 8;
y ranges from 0 to less than 4;
z=12−
2a−
b−
c; and
M is Na or Li, prepared by a method, comprising;
precipitating a magnesium silicate having the desired value of “
a”
in a slurry by combining an aqueous solution of a water soluble magnesium salt with an aqueous alkaline solution of one or more sodium compounds in the presence of dissolved silicon-delivering material, the pH of the alkaline solution being maintained at 8 to 12.5 throughout to form an aqueous slurry;
hydrothermally treating the aqueous slurry in a pipe reactor at a temperature ranging from 210°
C. to 400°
C. and under a pressure of at least 20 bar for 10 seconds to 4 hours to from synthetic magnesium silicate crystals, wherein the aqueous slurry is not washed and filtered before it is hydrothermally treated; and
washing and filtering the washing and filtering the synthetic magnesium silicate to remove water soluble salts formed in the preparation of the aqueous slurry.
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Specification