PL196776B1 - Method of regenerating zinc containing hydrochloric acid solutions - Google Patents

Abstract

A method of regenerating hydrochloric acid solutions containing zinc, characterized in that it is into a solution Hydrochloric acid containing zinc (II) and iron ions are added in a volume ratio 3: 1-1: 3 mixture of tributyl phosphate and di (2-ethylhexyl) phosphoric acid, the components of this the mixtures are in the volume ratio in the range of 10: 1, preferably 3: 1, and then the whole is mixed, set aside for phase separation and then the lower phase is removed in a known manner.

Description

REPUBLIC

POLAND

Patent Office of the Republic of Poland (12) PATENT DESCRIPTION (19) PL (11) 196776 (13) B1 (21) Application number: 351460 (22) Application date: 31.12.2001 (51) Int.Cl.

C01G 9/00 (2006.01) C01G 49/00 (2006.01) C23G 1/36 (2006.01) C25D 21/16 (2006.01) (54) The method of regenerating hydrochloric acid solutions containing zinc (73) The patent holder:

Poznań University of Technology, Poznań, PL (43) Application was announced:

14.07.2003 BUP 14/03 (45) The following was announced about the grant of the patent:

31.01.2008 WUP 01/08 (72) Inventor (s):

Jan Szymanowski, Poznań, PL Ireneusz Miesiąc, Poznań, PL Ana M. Sastre, Barcelona, ES Magdalena Regel-Rosocka, Poznań, PL (74) Plenipotentiary:

Urbańska-Łuczak Barbara, Politechnika Poznańska ^{(57) A} method of regenerating hydrochloric acid solutions containing zinc, characterized in that to the hydrochloric acid solution containing zinc (II) and iron ions is added in a volume ratio of 3: 1-1: 3 a mixture of tributyl phosphate and di (2-ethylhexyl) phosphoric acid, the components of this mixture in a volume ratio in the range of 10: 1, preferably 3: 1, then the whole is mixed, left to stand for phase separation, and then the lower phase is removed in a known manner.

PL 196 776 B1

Description of the invention

The present invention relates to a process for the regeneration of zinc-containing hydrochloric acid solutions.

There are many methods of separating zinc from digestive solutions and regenerating these solutions. In the Ruthner method, hydrochloric acid solutions are regenerated by evaporating the solution and hydrolytic decomposition with the formation of iron oxides at a temperature of approx. 700 ° C. The implementation of this process is possible only when the content of zinc ions (Zn) in the starting solution is low, <0.5 g / dm ³ . This makes it impossible to regenerate solutions containing higher zinc contents.

It is common to neutralize digestive solutions with lime, but zinc is also largely removed when iron compounds are precipitated. However, the removal is not complete and the effluent obtained after the filtration of iron compounds still contains zinc ions in amounts (300 mg / dm ³ ) exceeding the permissible concentrations. The precipitate of iron compounds containing also zinc compounds requires their disposal in specially constructed landfills as zinc compounds are easily dissolved under the influence of atmospheric precipitation.

Zinc from aqueous solutions can be removed by extraction. A number of technological processes for this purpose are known. The most important of them are: ZINCEX - two-stage process of zinc extraction with the use of the secondary amine Amberlite LA 2, and then after re-extraction, extraction of zinc with di (2-ethylhexyl) phosphoric acid (D2EHPA), CANMET - two-stage zinc leaching; After precipitation of lead chloride (PbCl2) and copper-silver cementation with iron dust, the zinc is extracted with tributyl phosphate (TBP), after reextraction with chloride electrolyte, zinc electrolysis is carried out, CENIM-LNETI - extraction is preceded by the addition of a leaching agent in the form of anion chloride solution. Extraction of zinc with di (2-ethylhexyl) phosphoric acid is carried out only after copper extraction with extractant LIX 65 N.

The most commonly used zinc extractant is di (2-ethylhexyl) phosphoric acid, which allows for the effective separation of zinc ions from acid sulphate solutions. Therefore, the zinc cations are bound. It is also possible to use other organophosphinic acids, such as: dialkylphosphinic acids, dialkylmonothiophosphinic acids, dialkyldithiophosphinic acids and esters of alkylphosphonic acids. Similarly to dialkylphosphoric acids, phosphinic and phosphonic acids do not extract neutral and negatively charged zinc chloro complexes. Moreover, acid extractants extract iron (III) more strongly than zinc (II), not allowing for the selective release of zinc (II) in the presence of iron (III) ions.

Neutral extractants, including certain phosphoric acid esters, particularly tributyl phosphate (TBP) and trialkylphosphine oxides, can be used to isolate these chlorocomplexes.

Unfortunately, these reagents also very strongly complex iron (III) chlorocomplexes. It is therefore not possible to separate the zinc ions in the presence of iron, especially since there is always an excess of iron ions in the digestive solution.

The use of extraction forces the initial reduction of iron (III) to iron (II), which complicates the process and increases the processing costs. This does not fully solve the problem as iron (II) ions oxidize very readily to iron (III) on contact with air. Alkylamines can also be used to extract zinc chloro complexes.

However, also in this case the iron chlorocomplexes are coextracted and it is impossible to separate the zinc ions selectively.

Surprisingly, it turned out that the selectivity of the zinc ion separation in the presence of iron (III) ions can be increased by using a mixture of a solvating extractant, especially tributyl phosphate (TBP), and an acid extractant, especially di (2-ethylhexyl) phosphoric acid (D2EHPA).

The method of regenerating hydrochloric acid solutions containing zinc consists in adding a mixture of tributyl phosphate and di (2-ethylhexyl) phosphoric acid in a volume ratio of 3: 1-1: 3 to the hydrochloric acid solution containing zinc (II) and iron ions, the components of this mixture are in a ratio by volume in the range of 10: 1, preferably 3: 1, after which the whole is mixed, left to stand for phase separation and then the lower phase is removed in a known manner.

The di (2-ethylhexyl) phosphoric acid (D2EHPA) used in the invention does not extract zinc chlorocomplexes from digestive solutions, but it affects the extraction capacity of zinc and iron complexes from tributyl phosphate (TBP) by shifting the extraction equilibrium in a favorable direction, i.e. improving the selectivity of extraction zinc in the presence of iron (III).

Tributyl phosphate (TBP) co-extracts both zinc and iron ions and does not allow for their separation. Di (2-ethylhexyl) phosphoric acid (D2EHPA) does not transfer ions to the organic phase

In contrast, it carries large amounts of iron (III) ions (96.4%). On the other hand, extraction with mixtures of these extractants shows an equilibrium shift towards zinc extraction. Although the extraction of zinc ions decreases from 63% to 33%, the selectivity of extraction increases significantly as only 4.3-5.6% of iron is transferred to the organic phase, compared to 60.9% when using tributyl phosphate (TBP) alone. .

The following examples illustrate the essence of the invention:

P r z x l a d I.

To 0.01 dm ^{3 of a} 10% solution of hydrochloric acid (HCl) containing 0.485 g / dm ^{3 of} zinc (II) and 35.52 g / dm ^{3 of} iron (III), 0.01 dm ^{3 of} 100% tributyl phosphate (TBP) was added, after which it was shaken for about 15 minutes, and then it was left to stand for about 25, for phase separation. The resulting two layers were separated by removing the lower phase.

P r z x l a d II.

To 0.01 dm ^{3 of a} 10% solution of hydrochloric acid (HCl) containing 0.568 g / dm ^{3 of} zinc (II) and 30.72 g / dm ^{3 of} iron (III) was added 0.01 dm ^{3 of a} 30% solution of di (2- ethylhexyl) phosphorus (D2EHPA), then shaken for approx. 15 min., and then set aside for approx. 25, for phase separation. The resulting two layers were separated by removing the lower phase.

P r x l a d III.

To 0.01 dm ^{3 of a} 10% solution of hydrochloric acid (HCl) containing 0.485 g / dm ^{3 of} zinc (II) and 35.52 g / dm ^{3 of} iron (III), 0.005 dm ³ of tributyl phosphate (TBP) and 0.005 dm ^{3 were added.} % solution of di (2-ethylhexyl) phosphoric acid (D2EHPA), then shaken for approx. 15 min., and then set aside for approx. 25, for phase separation. The resulting two layers were separated by removing the lower phase.

P r x l a d IV.

To 0.01 dm ^{3 of a} 10% hydrochloric acid (HCl) solution containing 0.485 g / dm ^{3 of} zinc (II) and 35.52 g / dm ^{3 of} iron (III) was added 0.0065 dm ³ of tributyl phosphate (TBP) and 0, 0035 dm ^{3 of} a 30% solution of di (2-ethylhexyl) phosphoric acid (D2EHPA) and shaken for approx. 15 min., and then allowed to stand for approx. 25 for phase separation. The resulting two layers were separated by removing the lower phase.

P r z k ł a d V.

To 0.01 dm ^{3 of a} 10% solution of hydrochloric acid (HCl) containing 0.485 g / dm ^{3 of} zinc (II) and 35.52 g / dm ^{3 of} iron (III), 0.0075 dm ³ of tributyl phosphate (TBP) and 0, 0025 dm ^{3 of a} 30% solution of di (2-ethylhexyl) phosphoric acid (D2EHPA), then shaken for approx. 15 min., And then set aside for approx. 25, for phase separation. The resulting two layers were separated by removing the lower phase.

The results of the extractions carried out as in Examples 1-5 are shown in Table 1.

T a b e l a 1.

Percentage of zinc and iron (III) extraction from 10% HCl solution using mixtures of TBP and D2EHPA. (The composition of the feed phase in 10% HCl is given in columns 2 - 4).

Reagent Feed-in phase Extracted metal, % ^Z n ('' 3 g / dm ³ Fe (III) g / dm ³ Cl ^- M Zn (II) Fe (III) TBP 0.485 35.52 5.37 63.0 60.9 D2EHPA 0.568 30.72 5.06 0.00 96.4 TBP: D2EHPA = 1: 1 vol / Vol 0.485 35.52 5.37 33.5 4.3 TBP: D2EHPA = 2: 1 vol / vol 0.485 35.52 5.37 33.8 5.1 TBP: D2EHPA = 3: 1 vol / vol 0.485 35.52 5.37 44.3 5.6

Patent claim

Claims (2)

A method of regenerating hydrochloric acid solutions containing zinc, characterized in that to the hydrochloric acid solution containing zinc (II) and iron ions is added in a volume ratio 3: 1-1: 3 mixture of tributyl phosphate and di (2-ethylhexyl) phosphoric acid, the components of this mixture being in the volume ratio in the range of 10: 1, preferably 3: 1, then the whole is mixed and left for phase separation and then the lower phase is removed in a known manner.