CS197821B1 - Method of preparing concentrate eluate of heavy metals,especially of uranium - Google Patents

Description

The invention relates to a process for the preparation of a concentrated heavy metal eluate, in particular uranium, starting from a primary heavy metal treatment by ion exchange sorption and pre-elution to the primary eluate.

In hydrometallurgical processing of ores, especially uranium, uranium is sorbed from clear solutions or mashes on strongly basic anion exchangers. Elution is carried out with solutions of mineral acids or salts of various concentrations. From the eluates, uranium is precipitated to a low quality chemical concentrate which is further concentrated, sedimented and filtered. The eluates that are processed to a chemical concentrate generally contain 1 to 40 grams of uranium per liter and about 1 to 2 moles of free acid or salt. The precipitation of uranium from such solutions is associated with a number of adverse effects, such as the treatment of large volumes of liquids and suspensions, high chemical consumption, poor sedimentation properties, relatively low uranium content in the concentrate.

The aforementioned drawbacks are eliminated by a process for the preparation of a concentrated heavy metal eluate, in particular uranium according to the invention, which comprises treating the primary eluate in a cation exchange sorption process with a cation exchange resin, and then treating the heavy metal cation exchange resin. in the effluent elution process with a mineral acid, the reacted cation exchanger from the effluent elution process being fed back into the cation exchanger, the waste solution of which a197 821 of the primary eluate can advantageously be adjusted to a pH of 3-4 or 6.5 to 8 prior to the cation exchange sorption process. A weakly acidic carboxylic cation exchanger made from methacrylic acid polymer 8 with divinylbenzene can be used as the cation exchanger.

The process according to the invention removes the drawbacks of the prior art processing of the eluate by precipitation and filtration with drying, in particular by achieving substantially cleaner concentrates, in the order of tens of percent while increasing the circulation of the pure metal. In addition, in the final processing, ee has a favorable effect on energy consumption and chemicals.

The process according to the invention is particularly suitable for concentrating uranium in the processing of uranium ores. However, this treatment method can also be used to concentrate other heavy metals.

The process according to the invention is based on the fact that the heavy metal leachate is treated by ion exchange sorption and pre-elution up to a primary metal eluate with a low metal content and greatly contaminated by salt additions. According to the process of the invention, this primary eluate is treated with a cation exchange resin in a cation exchange sorption process. A weakly acidic carboxylic cation exchanger made on the basis of a methacrylic acid polymer with divinylbenzene can be used as the cation exchanger. In addition, the heavy metal-not adsorbed cation exchanger is treated with a sulfuric acid mineral acid in the final elution process. The concentrated eluate obtained is fed from the final elution process to further conventional operations, namely precipitation, filtration and drying. The reacted or greenish cation exchanger is returned from the effluent elution process back to the cation exchange sorbent, the waste solution of which is returned to the preparation of the elution agent for pre-elution. Prior to the cation exchange sorption process, the primary eluate should be adjusted so that the pH of the solution is between pH 3-4 and pH 6.5 to 8, respectively.

Example 1

Nitrate eluate from strongly basic anion exchange resin in one liter of 12 g uranium and 30 g HNOg was neutralized with an aqueous ammonia solution to pH 3.5. The neutralized solution was pumped onto a laboratory column containing a weakly acidic cation exchange resin in NH ₄ ⁺ -form, at a rate of 1 volume solution per 1 volume cation exchange per hour. After the uranium cation exchanger was ^{saturated with} 15% ^H 2 ^SO 4 ^{and 0.6} ° volume per volume of cation exchanger. The concentrated concentrated eluate contained 110 g uranium and 40 g H ₂ SO ₄ per liter.

Example 2

The sulphate eluate from a strongly basic anion exchange resin containing 10 g of uranium and 10 g of Na ₂ CO ₂ per liter was neutralized with a sulfuric acid solution to pH 6.5. The neutralized ee solution was pumped onto a laboratory column containing a weakly acidic cation exchange resin in NH ₄ ⁺ -form, at a rate of 1 volume solution per 1 cation exchange volume per hour. After saturation cation uranium was eluted with 15% ^H 2 ^S0 4 ^{0.6 AEI} bj®mu ° and 1 volume of the cation exchanger. The concentrated eluate obtained contained 95 g of uranium per 28 g of H 2 per liter _. SO _d 3

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Claims (4)

SUBJECT OF THE INVENTION A process for the preparation of a concentrated heavy metal eluate, in particular uranium, starting from a primary treatment of a heavy metal leachate carried out by ion exchange sorption and pre-elution up to the primary eluate, characterized in that the primary eluate is treated with a cation exchange sorption process. the metal-absorbed cation exchanger is treated in the effluent elution process with a mineral acid, wherein the reacted cation exchanger from the effluent elution process is recycled to the cation exchange sorbent, the waste solution of which is at least partially introduced as an eluting agent into the preliminary elution process, 2. The process of claim 1 wherein the pH of the primary eluate is adjusted to a pH of 3-4 before the cation exchange sorption process. 3. The process of claim 1 wherein the pH of the primary eluate is adjusted to a pH of 6.5 to 8 prior to the cation exchange sorption process. 4. Process according to claim 1 or 2 or 3, characterized in that a weakly acidic carboxylic cation exchanger based on a methacrylic acid polymer with divinylbenzene is used as the cation exchanger.