Chemistry of inorganic compounds – Treating mixture to obtain metal containing compound – Group iva metal
Patent
1991-09-25
1994-01-11
Brunsman, David
Chemistry of inorganic compounds
Treating mixture to obtain metal containing compound
Group iva metal
423 98, C01G 1700
Patent
active
052778827
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for separating germanium from a germanium-bearing aqueous sulphate solution, according to which said solution is brought into contact with an organic phase, containing a substituted 8-hydroxyquinoline and an organophosphorus compound, said contact being operated at a pH at which the organic phase is loaded with germanium.
Such a process is described in EP-A-199905. In this known process one starts for instance form a sulphate solution with 220 mg Ge/l, 110 g Zn/l and 32 g H.sub.2 SO.sub.4 /l, originating from flue dust leaching. This solution is brought into contact at 35.degree. C. with an organic phase, containing a mixture of substituted 8-hydroxyquinolines as well as tri-n-octylphosphinoxide (TOPO), for instance a solution composed of 15% in volume of a hydroxyquinoline mixture, 0.1 mol TOPO, 40% in volume of isodecanol and, for the remaining, kerosene; the hydroxyquinoline mixture itself is composed of 10% in volume of "Kelex 100" and 90% in volume of "LIX 26", Kelex 100 and LIX 26 being trade names for extracting agents containing one or more substituted 8-hydroxyquinolines as active component. At the low pH that sets up when the acid starting solution (32 g H.sub.2 SO.sub.4 /l) is brought into contact with the organic phase, the largest part of the germanium is transferred from the starting solution into the organic phase from which germanium is recovered afterwards by treatment with a NaOH solution.
This known process is especially directed to the recovery of germanium from solutions originating as an intermediate product or a by-product in the extractive metallurgy of metals such as Al, Pb, Cu and Zn. However, these solutions can contain, besides Ge, also In and/or Ga, particularly when solutions from the zinc metallurgy are concerned. To treat solutions containing besides Ge, also In and/or Ga, this known process is less suited in that sense that it does not enable to transfer in one an the same operation Ge, In and Ga into the organic phase.
The aim of the present invention is to provide a process such as defined herebefore enabling, when the germanium-bearing aqueous sulphate solution contains In and/or Ga, to transfer in one and the same operation these elements into the organic phase, together with germanium.
This invention is based on the discovery that a mixture of a substituted 8-hydroxyquinoline and an organophosphorus compound containing at least one phosphorus-bearing acid function, exhibits a strong synergy for the extraction of Ge as well as of In and Ga from a weak acid sulphate medium.
The process according to the invention is characterized in that one used an indium and/or gallium containing germanium-bearing aqueous sulphate solution as said germanium-bearing aqueous sulphate solution, one uses a compound containing at least one phosphorus-bearing acid function as said organophosphorus compound and one operates said contact at a pH of 0.5-2.5 in the presence of indium and gallium as well as in the absence of gallium and at a pH of 0.5-4 in the absence of indium, whereby the organic phase loads itself with indium and/or gallium too.
Operating said contact at a given pH, e.g. at pH 2, means here that the acidity of the aqueous solution and/or of the organic phase before and/or during their contact is adjusted in such a way that the aqueous solution has a pH of 2 at the moment the contact between both phases will be interrupted, which normally happens when the chemical equilibrium between both phases is reached or almost reached.
When the germanium-bearing starting solution contains both indium and gallium, it is necessary to operate said contact at a pH of 0.5-2.5; if one operates at a pH lower than 0.5, then indium and gallium are insufficiently extracted and at a pH exceeding 2.5 indium precipitates; one operates preferably at pH 1-2.5 and most preferably at pH 1-2, for example at pH 1.5-1.7. When the germanium-bearing starting solution contains indium but no gallium, it is also necessary to operate said contact at a pH of 0.5-2.5, since
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De Schepper Achille J.
Haesebroek Guy G.
Vliegen Jean H.
Brunsman David
Union Miniere s.a.
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