Liquid purification or separation – Processes – Liquid/liquid solvent or colloidal extraction or diffusing...
Reexamination Certificate
2002-07-09
2004-12-07
Walker, W. L. (Department: 1723)
Liquid purification or separation
Processes
Liquid/liquid solvent or colloidal extraction or diffusing...
C210S652000, C210S660000, C210S688000, C423S019000, C423S502000, C423S486000
Reexamination Certificate
active
06827856
ABSTRACT:
The present invention relates to a process for the recovery of copper contained in solutions from the recovery of iodine from industrial waste streams from the production of ionic and non-ionic iodinated X-ray contrast agents. The process is particularly valuable when the above mentioned waste streams derive from the recovery of iodine by mineralization with finely dispersed metal copper and copper ion solutions.
The recovery of iodine from solutions containing iodinated organic compounds, in particular ionic and non-ionic X-ray contrast agents, is the solution to a both environmental and economic problem.
Iodine has, in fact, to be recovered from the effluents and waste streams from the production of 2,4,6-triiodo-1,3-benzenedicarboxylic acid derivatives due to its high intrinsic cost as well as to the need for reducing the environmental impact deriving from its production.
Law regulations in many Countries have in fact established very strict standards, setting the presence of organic aromatic compounds in waste streams namely to some ppm.
In particular, Italian law does not allow wastes to contain above 0.4 ppm of organic aromatics: it is therefore mandatory for such molecules to undergo degradation while recovering iodine.
This problem has been known for some time, and a number of patent applications concerning the process for the recovery of iodine have been filed (see, for instance: WO 98/07661, WO 94/10083, EP 106934).
More particularly, EP 106,934 discloses a process for the mineralisation of iodine, which comprises heating the recovery solutions containing the ionic and non-ionic contrast agents for a time of 30 minutes-2 hours at a temperature of 100-150° C. in the presence of strong alkali and copper ions or finely dispersed copper in amounts ranging from 100 to 2,500 ppm, which can be a further environmental problem.
Patent application WO 00/32303 discloses a process further improving the conditions for the recovery of iodine from industrial wastes from the production of ionic and non-ionic iodinated X-ray contrast agents.
According to the cited patents, iodine can be recovered by use of oxidizing agents such as manganese dioxide, sodium chlorate, hydrogen peroxide, chlorine, sodium hypochlorite, nitrous acid.
Notwithstanding the various patents concerning processes for the mineralisation and recovery of iodine which make use of copper ions or finely dispersed copper, the problem of the recovery of copper from the mineralisation final solutions has yet to be solved.
The toxicity of metals is well-documented in literature and their presence in industrial waste streams may have potentially toxic effect on animal and aquatic life. In fact, while organic pollutants can be subjected to degradation to harmless products, metals do not undergo degradation and can therefore accumulate in the fat tissues of living organisms, reaching concentrations in excess to those which originally existed in air or water.
In order to protect the environment from such contaminants, discharge of heavy metal containing waste streams is subject to strict regulations.
Electronic and pharmaceutical industries, for example, produce high volumes of industrial wastes having a particularly high content in heavy metals and copper ions. These effluents cannot be directly discharged in the environment and have to previously undergo an expensive treatment to ensure the reduction in their metal content.
More particularly, Italian law is very strict as far as the copper residual content dumped in the environment is concerned, setting a maximum tolerance of totally 0.4 ppm of copper in the wastes from a single industrial plant.
The process disclosed in the above cited WO 00/32303 for the recovery of iodine contained in solutions from wastes from the production of ionic and non-ionic contrast agents, makes use of copper ion or finely dispersed copper as a catalyst, in amounts ranging from 100 to 2,500 ppm and this can be an environmental problem.
In literature some processes are known for removing metal ions from aqueous solutions, but not from solutions deriving from the recovery of iodine from waste streams from the production of ionic and non-ionic X-ray contrast agents.
U.S. Pat. No. 5,122,279 discloses a process for removing the copper ion from a solution, which comprises treatment with ferrous dithionate to precipitate the corresponding metal complex from the solution, thus allowing for the metal to be separated.
Furthermore (see for example: U.S. Pat. Nos. 3,640,703, 3,790,370, 5,783,057) some chemical processes for the recovery of copper are known, which involve the use of sodium sulfide or hydrogen sulfide.
However these procedures, while easy to carry out in laboratory, are hardly industrially workable in that the addition of sodium sulfide or hydrogen sulfide causes unavoidable bad smell as well as a high contamination load.
U.S. Pat. No. 4,428,773 discloses a process for the treatment and recovery of copper and copper oxide from industrial wastes, in which copper and copper oxide are precipitated from the solution in alkali medium.
U.S. Pat. No. 4,343,706 discloses a process in which copper is recovered from industrial waste streams by precipitation from the solution at basic pH and in the presence of ferric ions, used both for their reducing properties and for their coagulant and flocculant properties.
Analogously, U.S. Pat. No. 5,472,618 discloses a method for recovering copper, which makes use of the reducing properties of a metal such as iron at acid pH and allows to recover the precipitated metal copper at the end of the treatment.
Some patents concerning the galvanic and metal working industries are known, which disclose (see for example U.S. Pat. Nos. 5,200,473, H0001661, 5,198,021, 4,070,281) the use of chelating cationic resins for removing metal ions from solutions containing the metal complexed for example with cyanide ions.
U.S. Pat. No. 5,262,018 discloses a process for the recovery of metals from solutions deriving from peroxy compounds, which comprises the use of ion exchange resins.
Similarly, the use of ion exchange resins for the recovery of metals is discloses in some process patents (see e.g. U.S. Pat. Nos. 5,907,037, 4,500,396, 5,907,037).
However, the cited literature describes processes for the recovery of both metal and ion copper which are either unsatisfactory or exceedingly costly for such an industrial application.
It has now surprisingly been found, and it is the object of the present invention, a process which, in addition to completely remove copper from the solution, also makes it possible to recover it in the form of a chloride or a sulfate so as to reuse it in the mineralisation process.
The process for the recovery of copper consists of multiple steps which are carried out considering the content in inorganic ions and organic products in the solution deriving from industrial waste streams from the production of ionic and nonionic iodinated X-ray contrast agents.
The present invention relates to a process for the recovery of copper from solutions deriving from the recovery of iodine from production wastes from the production of ionic and non-ionic iodinated X-ray contrast agents.
The process is particularly suitable when the above mentioned waste streams derive from the recovery of iodine by mineralisation with finely dispersed metal copper and copper ions solutions and comprises the following steps:
1. percolating the solution from industrial waste streams on chelating resins suitable for removing copper;
2. displacing copper and regenerating the resins with a 10% hydrochloric acid or 10% sulfuric acid solution.
Step 1 is conducted by percolation on iminoacetic, aminophosphonic or carboxylic resins and it allows to selectively retain copper while discharging the metal-free solution eluted from the column, thus avoiding environmental problems. Suitable resins are selected from the group consisting of: Duolite C467®, Amberlite IRC 86® and IRC 748®, or commercial equivalents thereof capable of selectively removing copper.
In case of industrial wastes containing
Desantis Nicola
Incandela Salvatore
Bracco Imaging S.p.A.
Menon K S
Walker W. L.
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