The method of preparation of spent catalysts comprising a carrier containing at least one noble metal, for subsequent extraction of this metal

 

(57) Abstract:

The invention relates to low-hydrometallurgy of precious metals, in particular the removal of spent catalysts on carriers. We propose a method of preparation of spent catalysts comprising a carrier containing at least one noble metal, for subsequent extraction of this metal, including heat treatment under certain conditions. The heat treatment is performed at 450 to 650oC, followed by heat treatment at 700 - 1200oC in a reducing or oxidizing gas environment. The proposed method allows to increase the degree of extraction of precious metals, their purity. 3 C.p. f-crystals, 1 table.

The method of preparation of spent catalysts comprising a carrier containing at least one noble metal, for subsequent extraction of this metal.

The invention relates to low-hydrometallurgy of precious metals, in particular to the extraction of precious metals from spent catalysts on carriers.

There are various ways of extracting precious metals Ag, Pt, Pd and al from spent catalysts based on media type Al2

There is a method of treatment of the deactivated catalyst containing at least one noble metal (Application France N 2671104, MKI5C 22 B 11/00, 21/04, 61/00, B 01 J 38/72, 1992). The catalyst extracted from industrial installations, burn in critical conditions, then subjected to the heat treatment in the presence of an alkaline base in the molten state.

The disadvantage of this method is that the use of it in the technology of extraction of precious metals, which are based on the dissolution of the precious metal and the subsequent allocation of its solutions does not lead to full recovery of their high purity.

The closest method is a method of extraction of platinum, rhodium, palladium and gold from waste (A. S. Czechoslovakia N 255406, MKI4C 22 B 11/04 1985 ), in which the granular, crushed or powdered waste, spent catalysts, process oxidant type of ozonized oxygen, Cl2H2O, HNO3, HClO4CH3COOH in the environment of H2SO4and/or HCl at elevated temperature (up to the boiling point) and after rastitel from the group CHOH, HCOOH, glucose and other sugars. The temperature of the mixture maintained within the range of from 70oC to the boiling point. Precipitating precious metals removed by the recovery of known methods.

The disadvantage of this method is that together with noble metals in the solution passes and a portion of the carrier, thus reducing the degree of extraction of precious metals.

In many cases, the exhaust catalysts contain products of side reactions polymer resinous or coke deposits that interfere with the dissolution of noble metals and reduce their extraction into the solution. Spent catalysts are usually subjected to heat treatment in oxidizing environments. Thus, a certain proportion of the noble metal may be contacted by the media or passivated, which reduces the solubility of the metal. For example, leaching of silver from spent catalyst "silver on the pumice" solution of nitric acid in the media remains 2-15% of the contained in the catalyst metal.

The problem solved by the present invention is to develop a method of preparation of the material containing precious metals to fully extract them with you is tori, comprising a carrier containing at least one noble metal to the subsequent extraction of this metal, including heat treatment at a temperature of 450-650oC, followed by heat treatment at a temperature of 700-1200oC in a reducing or oxidizing gas environment.

Heat treatment at a temperature of 450-650oC is carried out in an inert gas environment when the oxygen content in the gas mixture is not more than 0.5 wt.%, then increase the oxygen concentration in the gas stream up to 20 wt.% and by the end of heat treatment as a gas environment of the use of atmospheric air.

After carrying out heat treatment in an oxidizing gas environment at a temperature of 700-1200oC conduct preemptive oxidizing gas environment with an inert gas, followed by an additional heat treatment at the same temperature in a reducing environment when introduced into the gas flow 5-20 wt.% gas reductant.

After treatment in a reducing environment at 700-1200oC carry out cooling in a reducing environment, then spend the displacement of the reducing gas environment with an inert gas, followed by a gradual flow of air.

To eliminate passivation or cuasialeatorios. The first stage is heated recyclable material to 450-650oC when the oxygen content in the gas mixture is not more than 0.5%, preferably in an inert gas environment).

Then the oxygen concentration in the gas stream is gradually increased up to 20%, without increasing the temperature in the layer of the processed material above 650oC. At the end stage of the oxidative heat treatment as the gas phase using atmospheric air. At this stage removes organic deposits.

In the second stage of heat treatment (temperature of 700-1200oC) when conducting it in an oxidizing atmosphere of oxidizing gas environment displace inert gas, then the gas flow is injected 5-20% of the gas reductant is hydrogen, mixtures of hydrogen with carbon monoxide, etc.

Then increase the temperature to 750-1200oC in a reducing environment. However due to a phase transformation decreases the solubility of the carrier, and restorative environment prevents the binding of the noble metal material media, favouring the diffusion of the metals on the surface of the particle carrier and eliminates the surface passivation of the metal particles.

Then produce a cooling material surface metal (usually around 100oC), and replacing the reducing gas environment with an inert gas, followed by a gradual flow of air.

Depending on the chemical nature of the carrier and a noble metal, the quantity of polymer-coke deposits in the catalyst suggest ways of preparing exhaust catalysts for the recovery of precious metals. So, in the absence of polymer-coke deposits heat treatment at a temperature of 700-1200oC is only in a reducing environment, in certain cases, the heat treatment at 700-1200oC is only performed in an oxidizing atmosphere.

Thus, the proposed set of features leads to the achievement of this goal and is new.

The following examples illustrate the proposed solution.

Example 1

Exhaust 2% palladium - alumina catalyst containing no polymer-coke depositions, prior to leaching of palladium subjected to heat treatment at 450-650oC in an inert environment. Then at a temperature of 700 - 900oC in a reducing gas environment (N2+ H2).

Example 2

Similar to example 1, except that as the recovery is ve reducing gas environment of the use of N2+NH3.

Example 4

Similar to example 1, except that as the reducing gas environment of the use of N2+CH3OH.

Example 5 (comparative)

Extraction of palladium carried out without preliminary heat treatment, the degree of oxidation of the palladium is less than 50%.

Example 6 (comparative)

Analogous to example 5, only the degree of oxidation of palladium is greater than 50%.

Example 7 (prototype)

From spent catalyst "silver on the pumice of the process of obtaining formalin containing 38.5% of silver, the latter vasilakopoulos 25% solution of nitric acid, followed by repeated rinsing with water. The degree of extraction of silver in a solution of 95%.

Example 8

Remove the silver analogously to example 7, only carried out in order to remove coke deposits heat treatment at a temperature of 650oC in an oxidizing environment. Then raise the temperature to 700oC and carry out the treatment in an oxidizing atmosphere.

Example 9

Similar to example 8, only after treatment in an oxidizing atmosphere spend processing in a reducing gas environment (N2+10% H2) at a temperature of 700oC and then cooled in the regenerative what odaca air.

Example 10

Similar to example 9, only as a restorative environment of the use of N2+10% CH3OH, and conducting heat treatment at a temperature of 900oC.

Example 11 (comparative)

Platinum recovery from spent aluminium oxide-platinum catalyst reforming of gasoline fractions. The content of platinum in the material of 0.45%, samaccount 18%.

The solvent is 20% aqueous solution of hydrochloric acid containing 2-3 g/DM3free chlorine.

Without prior heat treatment of the source material is poorly wetted by the solution and the leaching of platinum is hardly taking place.

Example 12 (comparative)

Analogous to example 11, only performed a preliminary heat treatment at temperatures up to 650oC in an oxidizing atmosphere to remove the coke deposits. After such heat treatment in the solution passes 60-70% of platinum and up to 80% of the material medium.

Example 13

Similar to example 12, only after removal of the coke material is additionally calcined at a temperature of 1000oC in air. Removing platinum 70-75%, the solubility of the material of the carrier of ~ 5%.

Example 14

Similar to example 13, only after removing cockaday in the same atmosphere to 100oC.

Extraction of platinum in the solution was 98-99,2%.

Analyzing the results for the recovery of precious materials from spent catalysts with preliminary preparation of the material and without conducting such training (see table.1), it was found that all of these materials need some pre-processing to remove the adsorbed substances. Such pre-treatment is of great importance as it strongly influences the degree of extraction of precious metals, the purity.

Thus, the essential distinguishing features of the invention are:

the heat treatment is carried out at a temperature of 450-650oC;

- this is followed by a heat treatment at a temperature of 700-1200oC in a reducing or oxidizing gas environment.

When processing in the proposed terms of the noble metal becomes more soluble, and dissolved solid solutions with the material of the carrier and transport of noble metals on the surface of the material medium.

1. The method of preparation of spent catalysts comprising a carrier containing at least one noble metal, subsequent to which moorebank carried out at 450 - 650oWith, then conduct the heat treatment at 700 - 1200oWith in a reducing or oxidizing gas environment.

2. The method according to p. 1, characterized in that the heat treatment at 450 - 650oWith carried out in an inert gas environment when the oxygen content in the gas mixture is not more than 0.5 wt.%, then increase the oxygen concentration in the gas stream up to 20 wt. % and by the end of heat treatment as a gas environment of the use of atmospheric air.

3. The method according to p. 1 or 2, characterized in that after the heat treatment in an oxidizing gas environment at 700 - 1200oTo carry out the displacement of the oxidizing gas environment with an inert gas, followed by an additional heat treatment at the same temperature in a reducing environment when introduced into the gas stream 5 to 20 wt.% gas reductant.

4. The method according to p. 1, characterized in that after heat treatment in a reducing environment at 700 - 1200oTo carry out cooling in a reducing environment, then spend the displacement of the reducing gas environment with an inert gas, followed by a gradual flow of air.

 

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