LU81602A1 - PROCESS FOR RECOVERY OF NON-FERROUS METALS CONTAINED IN A RESIDUE RICH IN IRON OXIDE AND / OR HYDROXIDE - Google Patents

Description

* -1-.

the present invention relates to a process for recovering non-ferrous metals contained in a residue rich in iron oxide and / or hydroxide, obtained during the hydrometallurgical treatment of zinc ores.

In the production of zinc by hydro-metallurgical route, the leaching of ores goes hand in hand, depending on their composition, with the dissolution of more or less significant quantities of iron. One method for separating this iron from the leaching liquor consists in precipitating it by hydrolysis in the form of an oxidizable compound which is well filterable such as goethite or hematite. This hydrolysis releases H2SQ4 which must be neutralized since it must be carried out at a well defined point.

Most often, as a neutralizing agent, toasted blende is used and the residue of this neutralizing blende is then found in the iron precipitate. This blende residue partially consists of zinc ferrites; there are also other non-ferrous metals such as Cu, In, Ge and Cd. After filtration, one obtains on the one hand a ferrous leaching liquor and on the other hand the residue rich in oxide and / or hydroxide of iron containing non-ferrous metals, targeted by the present invention.

the aim of the present invention is to provide a process making it possible to economically recover the non-ferrous metals contained in this residue and to obtain at? / f - / - 2 - both a residue rich in recoverable iron for example as a pigment or iron ore.

To this end, the residue is treated according to the invention with a sulfating agent between approximately 500 and approximately 750 ° C., thereby selectively sulfating the non-ferrous metals, and the sulfated metals are separated from the residue by leaching.

It is essential to carry out sulfation between about 500 and about 750 ° 0, because, if one operates below about 500 ° C, one produces significant quantities of iron sulfate, and, if one operates with- above about 750 ° C, the zinc sulfation rate is too low. It is advantageous to operate between approximately 550 and approximately 650 ° C., because in this range the most selective sulfation of the non-ferrous metals is obtained.

The reaction time required to obtain the desired result depends to a large extent on the possibilities of contact between the residue and the sulfating agent and, consequently, on the apparatus used to carry out the sulfation. It goes without saying that this duration can easily be determined, for each particular case, experimentally.

As a sulfating agent, H2SO4 and / or SO3 are advantageously used. This is how sulfation can be carried out with H2SO4 or with a gas containing SO3, this gas being obtained either by the decomposition of SO2SO4 or a sulfate, or in an installation / f - 3 - making H2SO4 by the contact process »We can further enrich this sulfating gas by injecting H2SO4.

The selectively sulfated residue is advantageously leached with acidulated water at a pH ranging from 1 to 5, preferably from 1 to 2, to avoid hydrolysis of the sulfates, and at a temperature between room temperature and about 90 °. C, preferably at a temperature ranging from about 20 to about 60 ° C.

It is particularly useful to carry out leaching against the current, this method making it possible to obtain concentrated solutions of non-ferrous metals.

The following examples will better understand the process of the invention and its advantages.

These examples relate to the treatment of a wet residue rich in goethite taken directly from the filter used to separate it from the bare leach liquor.

This wet residue ($ 42 by weight of water) contains in the dry state, * in $ by weight: 7.15 Zn; 41.2 Ee; 0.06 In; 0.82 or

Example 1

1 kg of residue is mixed with 10 $ by weight of 36 SO 2 H 2 SO 4 and the mixture is calcined at 600 ° C. for 2 hours. The calcination residue is leached for 2 hours at 60 ° C in 5 liters of water acidified with H2SO4 / up to a pH between 1 and 2. 'Æ ΐ - 4 -

Composition of the leaching residue, in $ by weight: 1 Zn; 60.5 Ee; 0.011 In; 0.09 Cu.

Yields in solution (or extraction), in fo: 90 Zn; 6 th; 87.5 In; 93 Cu.

Example 2

0.5 kg of residue is dried at 120 ° C. and the dried residue is ground.

„A basket containing 0.1 kg of this dry residue is placed in a tubular oven, which is heated to 650 ° C. and through which it is passed for 1 hour and at a flow rate of 0.2 μm / hour. , a gas containing 7% by volume of SO3 and coming from an installation for manufacturing H2SO4 by the contact process.

The residue thus sulfated is leached for 2 hours at 60 ° C in 1 liter of water carried by H2SO4 at a pH between 1 and 2.

Composition of the leaching residue, in $ by weight: 1.05 Zn; 58.5 le; 0.014 In; 0.1 Cu.

Solution yields, in 5 ”: 92 Zn; '1.8 Ee; 94 Cu; 86 In.

Example 3

1 kg of residue is mixed with $ 5 by weight of H2SO4 361T and the mixture is calcined at 600 ° C. for 2 hours.

The residue thus sulphated is leached at 20 ° C. in / against the current with 1 liter of water brought to pH 1 with dχΔΙ f # * * * - 5 - "H2SO4" using 3 steps each having a duration of 1 hour.

Composition of leaching residue, in%. by weight: 1.5 Zn; 62 Fe; 0.1 Gu; 0.02 In.

Composition of the solution, in g / l: 95 Zn; 20 Fe; 9 Cu; 0.5 In; 0.25 Cd.

Such a solution can be treated by known techniques for the recovery of Zn, Gu, / 'In, Cd. // V,

Claims (12)

1. Method for recovering non-ferrous metals contained in a residue rich in iron oxide and / or iron hydroxide, obtained during the hydrometallurgical treatment of zinc ores, characterized in that the residue is treated with a sulfating agent between about 500 and about 750 ° C thereby selectively sulfating the non-ferrous metals, and the sulfated metals are separated from the residue by leaching. 2. Method according to claim 1, characterized in that the sulfation is carried out between approximately 550 and approximately 650 ° C. 3. Method according to claim 1 or 2, characterized in that one uses as * sulfating agent H2SO4 and / or SO3. 4. Method according to claim 3, characterized in that the sulfation is carried out using a gas containing SO3 and obtained by decomposition of H2SO4 or a sulfate. ”5- Method according to claim 3, characterized” * in that the sulfation is carried out using a gas containing SO3 and obtained in an installation for manufacturing H2SO4 by the contact process. 6. Method according to claim 5> characterized in that enriches the gas by injecting H2SO4./ l V. , * I 7. Method according to any one of the preceding claims, characterized in that a wet residue is treated. 8. Method according to any one of claims 1 to 3 and according to claim 7, characterized in that the residue is mixed with H2SO4 and the mixture thus obtained is heated to a temperature within the range of 'aforementioned temperatures. \ 9. Process according to any one of Claims 1 to 6 and according to Claim 7, characterized in that the residue is dried at a temperature between approximately 100 and approximately 200 ° C and the residue thus dried is treated with a gas containing SO3 at a temperature within the above-mentioned temperature range. 10. Method according to any one of the preceding claims, characterized in that the leaching is carried out with acidulated water at a pH ranging from 1 to 5 and at a temperature between room temperature and about 90 ° C. 11. Method according to claim 10, characterized ".in that the pH is maintained at a fixed value by addition of H2SO4. 12. Method according to any one of the preceding claims, characterized in that the leaching is carried out against the current. Dacsir.s: ....... p ^ rchos ..... â ......... C0.r-ïZ dor: 'i ....... À .... "........ s ...... ·. ·. ........ λ. *. '·. · ivSdC ..: ....... jt'. ....- .. cc ^ ri'.Ti!, / 1