SU924178A1 - Method for producing metal tin from wastes - Google Patents

Description

The invention relates to the production of metallic tin from waste, in particular to receive it from waste electrolytically.

A known method for producing metallic tin from waste by the electrolytic method (1).

The closest in technical essence and the achieved result is a method of obtaining metallic tin from waste, including ¹ removing it from tin-containing raw materials by electrolysis with subsequent remelting of the tin slurry obtained at the cathode [2].

The disadvantage of this method ¹ is a strong etching of the surface of the products hanged on the anode with an aqueous solution of hydrochloric acid. This makes it impossible to reuse products. ^{4 The} electrolyte used in such a process is contaminated with ions of other metals. it

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leads to contamination by impurities of other metals produced on the cathode tin residue.

The purpose of the invention is to increase the productivity of the process, increasing the yield and quality of the metal.

This goal is achieved by the fact that in the method of obtaining metallic tin from waste, including its extraction from tin-containing raw materials by electrolysis followed by remelting of tin sludge obtained at the cathode, the slurry is recycled by repeated electrolysis at a concentration of hydrogen chloride 50-400 g / l of acid and ion concentrate divalent tin 20-200 g / l at a current density of 2-50 A / dmL.

The method is as follows

in a way.

Defects tinned products

they are hung together with hanging fixtures, on which they are prokha3 92M78 4

galvanic processing, on the anode rod of the separation bath. In this bath, the process of electrolysis is carried out in an aqueous solution of caustic soda at a concentration of the last 80 ^ 5

120 g / l and a current density of 5 "10 A / dm. The electrolyte temperature is maintained between 60 and 90 ° C. When electrolysis is carried out with the above modes, a rather intensive dissolution of the tin coating on the treated parts occurs at a current density of 10 A / dm ^g up to 2-3 µm / min. As the accumulation of the intermediate product obtained on the steel cathodes of the bath 15, which is a dense, dark <almost black / mass, is cleared, the sludge pieces removed from the cathodes of the dilution bath go y bias towards the anode baths trunking to obtain tin metal.

In turn, the products from which tin was removed are unloaded from the decontamination bath · and sent to 25 repeated electroplating ·

The perforated anode box, which is filled with an intermediate product that can be removed from the cathodes of the dilution bath, is made of a material that is resistant to aggressive influences, for example, vinyl plastic or other plastic, and has insoluble conductive anodes, for example graphite ones, along its perimeter. The anode box is installed in the bath with an aqueous solution of hydrochloric acid, the concentration of hydrogen chloride 50 "

^ ♦ 00 g / l. Conductive shields (cathodes), which are made of corrosion-resistant material, such as titanium, are hung on the cathode rods used to produce metal tin.

At a constant concentration of tin in the form of 5p ^ in the electrolyte of the bath for the production of metal equal to 100 g / l, and the concentration of hydrogen chloride in acid 260 g / l, the yield of metallic tin from 1 dm of the cathode surface for 1 min depends on the cathode current density as follows ( see table).

Cathode density current A / dm®- five ten 15 20 25 thirty 36 38 41 Metal output lyric tin, g s g dm ^g- surface for 1 min 0.23 0.3 ** 0.5 0.65 0.8 1.0 1.75 2.06 2.5

EXAMPLE 1.Poluchenie metallic tin from waste representing an intermediate product removed from the alkaline bath razluzhivaniya cathodes, ⁴⁵ formed as follows Zoom.

Obtained during the electrochemical coating of steel products tinned on the copper sublayer in the electrolyte containing 100 g / l of hydrate of oxide, sodium at ⁵⁰ cathode current density 6 A / dm®, tin slurry is electrochemically dissolved in the anode box in acid containing hydrogen chloride at the latter concentration of 260 g / l at ⁵⁵ Ka todnoy current density of 15 a / dm®-tin concentration based on 8η ® · ⁴

100 g / l. ²

The yield of metallic tin from 1 dm of the surface of a titanium cathode for 1 min at an electrolyte temperature of 30 ° C is 0.5 g. The precipitate obtained at the cathode is large shiny dendritic crystals. Spectral analysis of the tin content in the sediment is determined to be 99.9%. After washing, drying, pressing and reflowing, the loss of tin from the amount initially obtained is 5%. The yield of tin metal is thus 95%.

PRI mme R 2. Obtained with

Electrochemical coating of tinned brass tartes in electrolyte,

{containing 80 g / l of oxide hydroxide nat5 924178

At a current density of 8 A / dm1, tin sludge is electrochemically dissolved in an anode box in an acid containing hydrogen chloride at a concentration of 400 g / l, at 5 current density of 36 A / dm ^ and tin concentration in the electrolyte: in terms of 5gR " 200 g / l. The yield of metallic tin, from 1 dm ^ of the surface of the titanium cathode per minute at 38 ° C is 2.35 g. The precipitate at the cathode is large shiny columnar crystals. The spectral analysis reveals the content of tin in the sediment equal to 99. , 89% · After washing, drying, 15 pressing and pressing The loss of tin from the initial amount obtained is 5.5%. The yield of tin metal is thus 94.5%.

Example Obtained by electrochemical coating of tinned products in an electrolyte containing 120 g / l of sodium hydroxide at a current density of 10 A / dm ^, tin sludge is electrochemically dissolved in an anode box, in an acid containing hydrogen chloride at a concentration of 50 g / l at a current density of 5 A / dm ^ and the concentration of tin in the electrolyte 20 g / l (in terms of 5η ² -). The yield of tin metal with 1 dm * ^ of the surface of the titanium cathode is 0.108 g per 1 minute at an electrolyte temperature of 24 ° C. The precipitate obtained at the cathode is in the form of small shiny crystals of a granular form. The tin content during spectral analysis in the. The resulting draft is 99.88%.

After washing, drying, pressing and refining, the loss of tin from the initially obtained amount is 6.5%.

The proposed method of obtaining metallic tin from waste, in contrast to the known methods, makes it possible to obtain a metal of high purity and without damaging the surface of the processed products due to the fact that anodic dissolution during

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thirty

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Electrolysis in an acidic medium does not undergo the processed products themselves, but an intermediate product obtained at the cathodes of alkaline decontamination baths. The method of obtaining metallic tin from waste allows increasing the productivity of the process without using expensive chemicals, complex and bulky equipment for its implementation due to the use of electrolytes with a high concentration of hydrochloric acid and high current densities during electrolysis. Furthermore, when using the proposed method decreases tin losses with sludge in remelting the ingot (5 ~ 6% loss of the inventive method, 19% ^- of the known).

Used when carrying out the proposed method, the electrolyte in contrast to those that are applied by known methods, is not prone to carbonate accumulation and loss, as a result of this working capacity, is simple to adjust.

Claims (1)

Claim The method of obtaining metallic tin from waste, including its extraction from tin-containing raw materials by electrolysis with subsequent remelting of tin sludge obtained at the cathode, characterized in that, in order to improve the process performance, increase the yield and quality of metal, tin sludge is processed by repeated electrolysis at a concentration of hydrogen chloride 50 -400 g / l acid and ion concentration of divalent tin 20200 g / l at. current density 2-50 A / dm * \