The method for extracting slurry containing platinum group metals

 

(57) Abstract:

The method relates to the technology of extracting sludge containing metals of platinum group, with the surfaces of the parts of the apparatus in industries that use catalysts based on platinum, and can be applied for extraction of platinum group metals from siliceous materials such as silica grids. The method includes processing the silicon-containing materials with solutions of fluoride and / or hydrohloride ammonium at 50-90oWith purging the reaction mixture with the air until the dissolution of silicon materials, Department of sludge containing platinum. The solution after separation of the sludge is neutralized with ammonia, the resulting precipitate silica is separated by filtration and the mother liquor is returned to the processing of silica mesh. The method allows to almost completely remove the platinum from porous silicon-containing materials in the form of slurries containing up to 60% platinum on closed processing circuit receiving as an additional product precipitated. 1 C.p. f-crystals, 1 table.

The invention relates to the technology of extracting sludge containing metals of platinum group, with surfaces and parts of machines in platinoid slurry of silicon-containing materials.

In the contact apparatus nitric acid production using silica mesh particulate slurry containing platinum, which is separated from the catalyst (platinum mesh) in the course of their operation. In the long-term operation on silica nets accumulate significant quantities of sludge. The content of platinum group metals in waste silica grids can be up to 1-3%.

Mechanical methods of removing cuttings do not provide a sufficiently high degree of extraction of platinum from silica nets due to their high porosity.

The method for extracting sludge containing platinum, with the surfaces on which the surface treatment are aqueous solution of an absorbent-acid with subsequent treatment of these surfaces with an aqueous solution of hydrogen peroxide [JP Application 56-14424, C 01 G 55/00, 1981].

The disadvantage of this method is the low degree of extraction of platinum group metals from materials having a porous structure.

Closest to the proposed method to the technical essence and the achieved result is a method by which extract platinum from spent catalysts based oxie connections in an amount of 0.1-2% in terms of fluorine in the 70oC, the precipitate was separated, and the solution allocate platinum known methods. As percoidei use HF, NH4F, NH4FHF and others [RJ metallurgy 1978, summary GP].

The disadvantage of this method is relatively incomplete extraction of platinum from porous silicon-containing materials.

The aim of the invention is to increase the degree of extraction of platinum group metals in the form of a slurry of a porous silicon-containing materials, in particular of silica nets.

The technical result achieved by the invention, is almost complete (99.9%) extraction of platinum from silicon-containing materials in the form of slurries containing up to 60% platinum, closed processing circuit receiving as an additional product precipitated.

This provides the possibility of regeneration and multiple re-use of solutions of fluoride and hydrohloride ammonium for processing silica nets.

The technical result is achieved by a method for extracting slurry containing platinum group metals, including treatment with a solution of fluoride and / or hydrohloride ammonia at a temperature of 50-90oWith the purging of the reaction mixture is the exact solution after separation of the sludge is treated with ammonia and after separation of the precipitate formed silicon dioxide returns to the processing of silicon-containing materials.

The difference of the proposed method is the handling of silicon-containing materials at 50-90oWith purging the reaction mixture with air.

The solution after separation of the sludge is neutralized with ammonia, the resulting precipitate silica is separated by filtration and the mother liquor is returned to the processing of silicon-containing materials.

Example 1. Take 1 kg of waste silica mesh with a platinum content of 1.93%, is placed in a container with a volume of 20 l and pour 15 l 21% solution hydrohloride ammonium. In the reaction mixture serves the air. Due to the heat of the reaction mixture is heated to 62oC. the Process is carried out to dissolve the silica mesh. After that, the solution is filtered, the filtered sludge is washed with water on the filter, dried, and weighed. Get 33,18 g slurry containing platinum to 58.1%. Extraction of platinum is 99.9%. The solution is cooled to 18oC, neutralized with ammonia to excess ammonia content of 6.6 g/l, incubated under stirring for 40 min and filtered to separate the silicon dioxide. The solution used for treatment of silica mesh. Silicon dioxide is washed with water, dried, get 960,4 g of white carbon black.

Example 2. Take 1 kg of neg is RA, obtained after separation of the silicon dioxide (example 1). The mixture is heated and treated with air. The process is carried out to dissolve the silica mesh. From the solution by filtration produce sludge, washed with water on the filter and dried. The solution recovered by the method of example 1. The results are shown in the table.

Example 3. Take 1 kg of waste silica mesh with a platinum content of 2.20%, is placed in a container with a volume of 20 l and pour 15 l 27% aqueous solution of ammonium fluoride. The mixture is heated to 80oWith, the vessel serves the air. The process is carried out to dissolve the silica mesh. The solution is filtered, isolated sludge washed with water on the filter and dried. Get 36,94 g sludge with a platinum content of 59.5%. Extraction of platinum is 99.9%. The solution recovered from obtaining precipitated by the method of example 1.

Example 4. Take 1 kg of waste silica mesh with a platinum content of 2.25%, is placed in a container with a volume of 20 liters and fill in 15 l of a solution containing 15% of hydrohloride ammonium and 15% of ammonium fluoride, the vessel served in the air to keep the temperature of the reaction mixture to 70oC. the Process is carried out to dissolve the silica mesh. The solution is filtered, isolated sludge washed with water, n is the target regenerate with obtaining precipitated by the method of example 1.

The proposed method compared with the method of the prototype can almost completely remove the platinum from kremnistyiy materials and to obtain a slurry containing platinum to 60% and additional product - silicon dioxide in a closed waste-free manufacturing scheme.

The process of digestions silicon-containing material with a solution of ammonium fluoride proceeds through the intermediate formation of hydrohloride ammonium, which then interacts with the silicon. Lowering the process temperature is below the 50oWith slow reaction formation hydrohloride ammonium, which leads to a sharp increase in the duration of the process and incomplete dissolution of silicon-containing materials. Increasing the process temperature over 90oWith impractical because does not lead to an increase in the content of platinum group metals in the sludge.

Purge the reaction mixture with air is to intensify the removal of ammonia from the solution and formation of hydrohloride ammonium.

1. The method of extraction of sludge containing metals of platinum group, silicon-containing materials, including the processing of solutions of fluoride and/or hydrohloride ammonium, de-sludging, distinguishing the notable the solution after separation of the sludge is treated with ammonia, separating the precipitated silicon dioxide, and the mother liquor is returned to the processing of silicon-containing materials.

 

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