Patent GB-1113613-A (GB)
Title: Adsorption or anti-caking agent and its preparation and use
IPC: B01J2/30
Filed: 1965-05-20
Abstract: A powdered adsorption or anti-caking agent with a bulk density below 200 g/l. comprises a mixture of an alkaline earth metal silicate and an alkaline earth metal phosphate precipitated from the same solution, the molar SiO2:P2O5 ratio in the mixture being 6:1 to 1:6 and the content of alkaline earth metal, calculated as oxide, being 10 to 50% by weight of the mixture. The agent is prepared by adding an aqueous mineral acid stronger than silicic acid (e.g. nitric or hydrochloric) to an aqueous alkali metal silicate solution (e.g. sodium silicate), with constant agitating, and if necessary heating until the solution shows a neutral to weak acid reaction, afterwards adding an excess of an aqueous solution or suspension of an alkaline earth metal salt and/or alkaline earth metal hydroxide (magnesium and calcium are exemplified) to the resultant mixture to form an alkaline earth metal silicate, precipitating the excess salt and/or hydroxide with phosphoric acid as alkaline earth metal phosphate and then filtering, washing and drying the product.  In a modified method a non-alkaline-reacting alkaline earth metal salt, e.g. magnesium chloride, is added to the silicic acid solution to form the alkaline earth metal silicate and the solution is made alkaline before the addition of the phosphoric acid with an alkaline-reacting alkali metal or ammonium salt (e.g. carbonate) or hydroxide.  In examples the agent is mixed with the following to prevent their caking: NaCl, NaHCO3, and mixtures of (1) BaSO4, (NH4)2SO4, (NH4)2HPO4, (2) NaH CO3, (NH4)2SO4, (NH4)2HPO4, NH4H2PO4; (3) NaHCO3, CaCO3; (4) MgNH4PO4.2H2O MgNH4PO4.6H2O; (5) (NH4)2SO4, NH4H2 PO4, H3BO4, Na2B4O7.10H2O.ALSO:A powdered adsorption or anti-caking agent with a bulk density below 200 g/l comprises a mixture of an alkaline earth metal silicate and an alkaline earth metal phosphate precipitated from the same solution, the molar SiO2:P2O5 ratio in the mixture being 6:1 to 1:6 and the content of alkaline earth metal, calculated as oxide being 10 to 50% by weight of the mixture.  The agent is prepared by adding an aqueous mineral acid stronger than silicic acid (e.g. HCl or HNO3) to an aqueous alkali metal silicate solution (e.g. sodium silicate), with constant agitating, and if necessary beating, until the solution shows a neutral to weak acid reaction afterwards adding an excess of an aqueous solution or suspension of an alkaline earth metal salt and/or alkaline earth metal hydroxide (Mg and Ca are exemplified) to the resultant mixture to form an alkaline earth metal silicate precipitating the excess salt and/or hydroxide with phosphonic acid as alkaline earth metal phosphate, and then filtering, washing and drying the product.  In a modified method a non-alkaline-reacting alkaline earth metal salt (e.g. MgCl2) is added to the silicic acid solution to form the alkaline earth metal silicate and the solution is made alkaline before the addition of the phosphonic acid with an alkaline-reacting alkali metal of ammonium salt (e.g. carbonate) or hydroxide.  In examples the agent is mixed with the following, to prevent their caking NaCl, NaHCO3 and mixtures of (1) BaSO4, (NH4)2SO4, (NH4)2HPO4 (2) NaHCO3 (NH4)2SO4 (NH4)2HPO4, NH4H2PO4 (3) NaHCO3, CaCO3 (4) MgNH4PO4.2H2O, MgNH4PO4.6H2O (5) (NH4)2SO4, NH4H2PO4, H3BO4, Na2B4O7.10H2O.ALSO:Fire extinguishing powders comprise powdered anti-caking agent with a bulk density below 200 g/l which agent is a mixture of an alkaline earth metal silicate and an alkaline earth metal phosphate precipitated from the same solution the water ratio SiO2 : P2O5 in the mixture being 6:1 to 1:6 and the content of alkaline earth metal calculated as oxide in the mixture being 10% to 50% by weight in admixture with any one of the following compositions (1) NaHCO3 (2) BaSO4, (NH4)2SO4 (NH4)2 HPO4 (3) NaHCO3, (NH4)2 SO4, (NH4)2, HPO4, NH4 H2 PO4 (4) NaHCO3, CaCO3 (5) MgNH4 PO4. 2H2O, MgNH4PO4. 6H2O and (6) (NH4)2 SO4, NH4 H2 PO4, H3BO4, Na2 B4O7. 10H2O.