Process for reducing the concentration of arsenic in an aqueous solution comprising a fluoroacid
AssigneeMexichem Fluor S.A. De C.V.
InventorsJuan Alberto Juarez Garcia, Iris Samantha Duran Castillo, Nilo Martinez Robles
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Abstract
A process for reducing the concentration of one or more arsenic-containing compounds in an aqueous solution comprising at least one fluoroacid, which process comprises: (i) contacting the aqueous solution with an oxidising agent to produce one or more Asv-containing compounds; and (ii) removal of precipitated arsenic-containing compounds; wherein the process comprises a step (iii) the addition of an aqueous alkali solution or slurry, which may take place after step (i) and before step (ii) or after step (ii).
Claims24
A process for reducing the concentration of one or more arsenic-containing compounds in an aqueous solution comprising at least one fluoroacid to form a treated aqueous solution comprising the fluoroacid, which process comprises:
- (i) contacting the aqueous solution with an oxidising agent to produce one or more precipitated AsV-containing compounds;
- and
- (ii) removal of precipitated arsenic-containing compounds;
- and
- (iii) the addition of an aqueous alkali solution or slurry, which may take place after step (i) and before step (ii) or after step (ii);
- wherein if the step (iii) takes place after step (ii) the process comprises a subsequent step (iv) of the removal of the precipitate resulting from step (iii);
- wherein the fluoroacid is present in an amount of from about 1 to about 50% by weight based on the total weight of the aqueous solution;
- wherein the addition of the oxidising agent is carried out at a temperature of from 0 to 30° C.;
- wherein step (iii) is carried out at a temperature of from about 0° C. to about 30° C.;
- and
- wherein in step (i) is carried out at an acidic pH and the oxidising agent is used in a stoichiometric excess of 20 or more times the quantity of oxidizable arsenic-containing compounds.
A process for reducing the concentration of one or more arsenic-containing compounds in an aqueous solution comprising at least one fluoroacid to form a treated aqueous solution comprising the fluoroacid, which process comprises:
- (i) contacting the aqueous solution with an oxidising agent to produce one or more precipitated AsV-containing compounds;
- and
- (ii) removal of precipitated arsenic-containing compounds;
- and
- (iii) the addition of an aqueous alkali solution or slurry, which may take place after step (i) and before step (ii) or after step (ii);
- wherein if the step (iii) takes place after step (ii) the process comprises a subsequent step (iv) of the removal of the precipitate resulting from step (iii);
- wherein the fluoroacid comprises fluorosilicic acid;
- wherein the addition of the oxidising agent is carried out at a temperature of from 0° C. to 30° C.;
- wherein step (iii) is carried out at a temperature of from about 0° C. to about 30° C.;
- wherein in step (i) the oxidising agent is used in a stoichiometric excess of 20 or more times the quantity of oxidizable arsenic-containing compounds, and the oxidising agent is selected from chlorine (Cl2), hypochlorite salts (M+ClO−), hypochlorous acid (HClO), hydrogen peroxide (H2O2) and permanganate salts (M+MnO4−) and mixtures thereof;
- and
- wherein the alkali is calcium hydroxide (Ca(OH)2) or calcium oxide (CaO).
Dependencies are inferred from the claim text.