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).
Claims28
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).
A process according to any of the preceding claims, wherein the one or more arsenic-containing compounds comprise AsF3 or a hydrolysed form of AsF3.
A process according to any of the preceding claims, wherein 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.
A process according to any of the preceding claims, wherein the removal of the precipitated arsenic-containing compounds comprises gravity-settling, filtration, anion-exchange resin or a combination thereof.
A process according to any of the preceding claims, wherein the alkali is calcium hydroxide (Ca(OH)2) or calcium oxide (CaO).
A process according to any of the preceding claims, further comprising dilution of the solution prior to the addition of the alkali solution or slurry.
A process according to any of the preceding claims, wherein the addition of the oxidising agent is carried out at a temperature of from about 0 to about 35° C.
A process according to any of the preceding claims, wherein step (i) is carried out in a time period of from about 1 to about 30 minutes.
A process according to any preceding claim, wherein in step (i) the oxidising agent is used in a stoichiometric excess relative to the quantity of oxidisable arsenic-containing compounds.
A process according to any of the preceding claims, wherein step (iii) is carried out at a temperature of from about 0 to about 35° C.
A process according to any of the preceding claims, wherein from about 50 to about 100% by weight of the arsenic-containing compounds is removed from the solution.
A process according to any of the preceding claims, wherein the treated solution contains about 5 ppm or less of arsenic-containing compounds.
A process according to any of the preceding claims, wherein the treated solution contains about 1 ppm or less of arsenic-containing compounds.
A process for the production of fluorosilicic acid comprising a process as defined in any of the preceding claims.
A process for the purification of fluorosilicic acid comprising a process as defined in any of the preceding claims.
A process for the production of HF comprising a process as defined in any of the preceding claims.
A process for the production of aluminium trifluoride (AlF3) comprising a process as defined in any of the preceding claims.
Dependencies are inferred from the claim text.