FI66650B - PROCEDURE FOR THE CONSTRUCTION OF FERRATION AND CONTAINING CONDITIONING - Google Patents

Description

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5 (51) Kv.ll2 / lnc.CI.3 C 22 B 19/26 j) (21) Patent application — Patentansöknlng 762066 ^ (22) Filing date - Ansökningsdag 16.07.7 6 (23) Starting date - Giltighetsdag 16.07.76 FINLAND “ * FINLAND (41) Has become public - Blivit offentlig 19-01.77 rp | \ (44) Date of issue and of publication of publication— V * V Ansökan utlagd och utl.skriften publicerad 31 .07.84 (45) Patent granted - Patent meddelat 12.1 1 .84

Patent and Registration Office

Patent · och registerstyrelsen (32) (33) (31) Privilege claimed - Begärd prloritet 18.07.75

Hoi An, Netherlands (NL) 7508611 * (73) Duolite International, Inc., 1100 Superior Avenue, Cleveland,

Ohio 1 * 1 * 114, USA (72) Gerrit Huibert van den Berg, Amsterdam, Wiihelmus Bracelets, Haarlem,

Kees Koerts, Oriebergen, Robert Smakman, Nigtevecht, Hoilanti-Hoiland (NL) (74) Oy Kolster Ab (51 *) Method for removing ferric ions from a concentrated aqueous zinc solution - Preparation of ferric ions from a concentrated aqueous zinc solution

The invention relates to a process for removing Ferri ions from a concentrated aqueous zinc solution.

When hydrometallurgically prepared zinc from zinc ore, zinc concentrates and residues, it is obtained in the form of a concentrated aqueous solution. However, depending on the quality of the ore and its pretreatment, the resulting solution contains, in addition to zinc, a considerable amount of ferric ions as well as relatively small amounts of other metal ions such as copper, cobalt, cadmium, arsenic, and antimony ions. Iron, which is present in solution mainly in the ferric form, greatly interferes with the subsequent processing of zinc and must therefore be removed. In practice, iron has so far been removed by precipitation. However, precipitation involves a significant loss of zinc and the zinc-containing precipitate is a waste problem as it is not easy to handle further.

The process according to the invention makes it possible to remove Ferri ions from a zinc solution by using an ion exchange process in which zinc 2 66650 is practically not bound to the ion exchanger. The zinc solution obtained is practically free of Ferri ions and the zinc content hardly decreases; zinc losses are virtually non-existent. The method also has the additional advantage that the ion exchanger is able to accept Ferri ions to such an extent that in the elution step iron is obtained in pure and high concentrations.

The process according to the invention is characterized in that a solution containing ferric and zinc ions, having a pH in the range of 0 to 1.3 as measured by a pH meter with a glass electrode, is contacted with a cation exchanger containing essentially aminocarboxylic acid and / or iminodicarboxylic acid groups.

Experiments have shown that other types of cation exchangers are not suitable for separating Ferri ions from zinc ions in this way. It has further been found that although a solid cation exchanger containing substantially aminocarboxylic acid groups and / or iminodicarboxylic acid groups (hereinafter referred to as a chelating resin) is used, the use of a standard pH range of 2-5 results in a relatively high zinc binding such that the Zn: Fe ratio in the chelating resin rises to an extent detrimental to the method. It is quite surprising that in the strongly acidic medium used according to the invention, the chelating resin absorbs such a large amount of Ferri ions from the zinc solution. Because normally at such a low pH, the chelating resin has a low binding capacity for heavy metals. In general, a chelating resin is used as the cation exchanger, although it is also possible to use a liquid cation exchanger containing essentially aminocarboxylic acid and iminodicarboxylic acid groups.

It should be noted that Canadian Patent CA 906,764 describes a process for removing metal ions, such as Ferro ions, from a relatively dilute zinc solution using a chelating resin in the pH range of 2-4 and, as exemplified, in the range of 3 to 3.9. However, it is clear that iron was only taken into account in the ferrous form, partly because at said pH values Ferri ions would precipitate as ferric hydroxide, which would greatly hamper the ion exchange process. Another disadvantage of the known method is that, when said pH values are used, the chelating resin binds significant amounts of Zn ions which, during elution, enter the eluate together with other metal ions in the starting solution.

3,66650 In practice, the zinc content of an aqueous solution is more generally at least 80 g / l and the Ferri ion content is usually about 10-30 g / l.

Before the aqueous solution containing ferric and zinc ions is contacted with the chelating resin, according to the invention, the measured pH of the solution is adjusted to 0 to 1.3, preferably to 0.2 to 1.1, unless the pH of the solution is already in that range when measured. The process is best performed in a sulfate medium obtained by treating zinc ore with sulfuric acid.

The chelating resin used contains a large number of aminocarboxylic acid and / or iminodicarboxylic acid groups having 1 to 5 carbon atoms per carboxylic acid group (including a carbon atom belonging to the carboxyl group), and preferably aminoacetic acid and / or iminodiacetic acid groups. The ratio of the number of carboxyl groups to the number of nitrogen atoms of the above-mentioned nitric carboxylic acid groups in the chelating resin is generally 0.8 to 2.0, and in practice generally 1.2 to 1.7. The nitrogen carboxylic acid groups of the above-mentioned chelating resin generally have a nitrogen content of 2 to 6 and in practice generally 3 to 4 milliequivalents per dry chelating resin in acid form. In practice, the binding capacity of the chelating resin is 1000 to 25,000 meq. the above-mentioned weak acid groups.

The chelate resin is known per se and can be prepared, e.g. must be hydrolysed. The chelating resin can also be prepared by reacting a halocarboxylic acid or a derivative thereof having 1 to 5 carbon atoms (including a carbon atom belonging to a carboxyl group) with a haloalkylated and then an aminated medium. The amination can be carried out using e.g. ammonia, ethylenediamine or polyamines such as tetraethylenepentamine. The binder is obtained by suspension polymerization of one or more non-generally unsaturated compounds, usually in the range of 10 to 160 ° C and in the presence of a starting radical such as azobisisobutyronitrile, benzoyl peroxide, lauryl peroxide and / or cumene hydroperoxide.

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To obtain a porous material, the polymerization may, if desired, be carried out in the presence of one or more compounds capable of precipitating or solvating the polymer to be prepared, e.g. hexane, heptane, cyclohexane, amyl alcohol, cyclohexanol, benzene, toluene and / or chlorobenzene. A linear polymer can be dissolved in the monomeric compound (s).

Suitable monomers for the preparation of the base polymer include, for example, aromatic monovinyl compounds such as styrene, vinyltoluene, vinylethylbenzene, vinylnaphthalene and vinylanisole, or mixtures of these compounds. It is preferred to use styrene. In the polymerization, said aromatic monovinyl compound (s) is (are) generally used in the presence of a crosslinking monomer in an amount not exceeding 50% by weight and preferably 3 to 18% by weight, based on the total amount of monomers. However, the use of a crosslinking monomer is optional. As the crosslinking monomer, a compound having at least two ethylenically unsaturated groups can be used, e.g. ethylene glycol dimethacrylate or vinyl methacrylate, but preferably aromatic di- or polyvinyl compounds such as divinyl-ethylbenzene, trivinylbenzene and especially technical. The preparation and composition of the chelating resin used in the invention are well known to those skilled in the art.

The chelating resin used according to the invention may be in either partially or completely salt form, e.g. as an alkali metal salt, a zinc salt or an ammonium salt. The resin can also be used in acid form. The chelating resin is generally used at 5-95 ° C, preferably at 20-90 ° C. The binding can be performed from the bottom up or from the top down using a commonly known ion exchange technique, e.g. one or more columns connected in series. The resin mattress can be either fully or partially fluidized. In order to achieve the best possible ion exchange and to make the zinc solution obtained as pure as possible, several statues connected to each other by the so-called carousel method or the rotation method are used. Regeneration can take place in the same or opposite direction as ion exchange, and can be performed, for example, using any of the above techniques. The prior art can be further used to reduce product and / or eluate dilution, such as by using systems in which a fluidized or non-fluidized resin and a liquid are fed countercurrent to each other.

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Once the chelate resin has bound the desired amount of Ferri ions, it is eluted. This can be done, for example, with a solution of hydrochloric acid or sulfuric acid or with another suitable eluent. The elution is generally carried out at a temperature between 10 ° C and the boiling point of the aqueous medium, preferably at 10-30 ° C. Elution of the chelate resin gives a solution containing mainly ferric salt, which can be further processed in a simple manner. It is particularly preferred that the chelating resin is eluted with hydrochloric acid, so that the Ferri chloride solution obtained can be easily converted back into usable hydrochloric acid as well as iron oxide.

Example

1 L of chelating resin with a loading capacity of 2000 meq / L of weakly acidic groups was applied to the statue; this resin was obtained by chloromethylating a porous copolymer containing 92% by weight of styrene and 8% by weight of divinylbenzene and then reacting it with the diethyl ester of iminodiacetic acid and hydrolyzing the product obtained. The nitrogen content of the dry chelating resin was about 3.5 meq / g. Next, an aqueous solution containing 2 l of 310 g / l of zinc sulphate, 90 g / l of ferrous sulphate and 20 g / l of sulfuric acid, pH 0.7, as measured by a pH meter with a glass electrode, was passed through the column at 80 ° C for one hour. After washing the statue with demineralized water at 80 ° C until zinc could no longer be detected in the effluent, the chelating resin was eluted with 2 liters of 10% hydrochloric acid at 20 ° C over one hour. It was found that the resin had bound 1470 meq / l Ferri ions and only 1 meq / l zinc ions.

When the above process was repeated using a strongly acidic cation exchanger with sulfonic acid groups (H + form, available under the trademark Imac C 12) and a weakly acidic cation exchanger with carboxyl groups (acid form, available under the trademark Imac Z5) that the ion exchanger had bound 145 meq / l Ferri ions and 1385 meq / l zinc ions and 188 meq / l Ferri ions and 34 meq / l zinc ions, respectively.

Claims (5)

6 66650 A method for removing ferric ions from a concentrated aqueous zinc solution, characterized in that a solution containing ferric and zinc ions having a pH in the range of 0 to 1.3 as measured by a pH meter with a glass electrode is contacted with a substantially aminocarboxylic acid and / or or with a cation exchanger containing iminodicarboxylic acid groups. Process according to Claim 1, characterized in that the measured pH of the aqueous solution is in the range from 0.2 to 1.1. Process according to Claim 1 or 2, characterized in that the cation exchanger contains aminocarboxylic acid and / or iminocarboxylic acid groups having 1 to 5 carbon atoms per carboxylic acid group, including a carbon atom belonging to the carboxylic acid group * Process according to one of Claims 1 to 3, characterized in that a solid cation exchanger is used which contains essentially aminocarboxylic acid and / or iminodicarboxylic acid groups. Process according to one of Claims 1 to 4, characterized in that the cation exchanger contains an aminoacetic acid and / or iminodiacetic acid group.