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GB2036801A - Separation of Arsenic from Tin - Google Patents

Separation of Arsenic from Tin Download PDF

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Publication number
GB2036801A
GB2036801A GB7846485A GB7846485A GB2036801A GB 2036801 A GB2036801 A GB 2036801A GB 7846485 A GB7846485 A GB 7846485A GB 7846485 A GB7846485 A GB 7846485A GB 2036801 A GB2036801 A GB 2036801A
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GB
United Kingdom
Prior art keywords
arsenic
tin
amount
weight
alloy
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB7846485A
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GB2036801B (en
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
RYAZAN Z PROIZV I OBRABOT TSVE
SP KONSTRUKT BJURO TYAZHEL TSV
Original Assignee
RYAZAN Z PROIZV I OBRABOT TSVE
SP KONSTRUKT BJURO TYAZHEL TSV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by RYAZAN Z PROIZV I OBRABOT TSVE, SP KONSTRUKT BJURO TYAZHEL TSV filed Critical RYAZAN Z PROIZV I OBRABOT TSVE
Priority to GB7846485A priority Critical patent/GB2036801B/en
Publication of GB2036801A publication Critical patent/GB2036801A/en
Application granted granted Critical
Publication of GB2036801B publication Critical patent/GB2036801B/en
Expired legal-status Critical Current

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Classifications

    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22BPRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B9/00General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
    • C22B9/10General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals with refining or fluxing agents; Use of materials therefor, e.g. slagging or scorifying agents
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22BPRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B25/00Obtaining tin
    • C22B25/08Refining
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22BPRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B30/00Obtaining antimony, arsenic or bismuth
    • C22B30/04Obtaining arsenic

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacture And Refinement Of Metals (AREA)

Abstract

Arsenic is separated from a mixture of tin and arsenic or a mixture of tin, arsenic and other metals by adding a mixture of potassium and sodium hydroxides and separating the skim that results. From 3 to 5 parts by weight of potassium hydroxide are used for every part by weight of sodium hydroxide, and this results in a dry granular skim being produced which is free from mechanical inclusions of metal droplets. A high degree of separation can therefore be achieved.

Description

SPECIFICATION Separation of Arsenic and Tin The present invention relates to a method of removing arsenic from tin alloys.
Arsenic has been removed from tin alloys by treatment with sodium hydroxide, but this does not work very well. We have now discovered a method of separation which is much more effective.
The present invention consists in a method of separating arsenic and tin, which comprises: agitating a molten mixture comprising arsenic and tin, together with sodium and potassium hydroxide, preferably in the ratio from 3 to 5 parts by weight of potassium to 1 part by weight of sodium; and skimming.
By means of this method it is possible to separate arsenic not only from alloys consisting solely of arsenic and tin, but also from more complicated alloys.
Very high degrees of purification can be achieved by this method; the amount of arsenic in the refined tin can easily be as low as from 0.01 to 0.04%. Also, the amount of tin lost during the separation can be reduced by from 9 to 10% by use of the method of the invention. The skim that is produced by this method is dry and granular and free from mechanical inclusions of metal droplets. Such skims are easily conveyed elsewhere for subsequent treatment.
The method of the invention may be carried out in the following way. A mixture of potassium and sodium hydroxide, preferably in a weight ratio of from 3 to 5 parts of potassium hydroxide to 1 part of sodium hydroxide is introduced into a molten alloy of tin and arsenic. Other metals, more usually non-ferrous metals, may of course be present in the alloy. This liquid is then agitated, for example by stirring, and preferably at a temperature of from 400 to 56O0C.
The arsenic in the melt reacts with the alkalies, and the product passes into the skim. The skim may change from liquid to solid, possibly in the form of granules, and this depends on the relative amount of potassium and sodium hydroxides. The preferred relative amount of potassium and sodium hydroxides (3:1 to 5:1) leads to a skim that is strong, dry and contains no mechanical inclusions of melt droplets.
These dry granular skims are then removed from the surface of the liquid.
The amount of hydroxides consumed during the method of the invention will depend on the amount of arsenic present in the original mixture.
The invention is further illustrated by the following examples Example 1 A tin and lead alloy containing 0.45% by weight of arsenic was treated by stirring it at a temperature of 500 C in the presence of a mixture of 4 parts by weight of potassium hydroxide and 1 part by weight of sodium hydroxide.
The amount of arsenic in the refined alloy was 0.1% by weight. The skim, which amounted to 6.5% by weight of the total amount of material, was obtained in the form of solid granules.
The amount of tin in the alloy was 93.5%.
Example 2 This was carried out as in example 1, but the relative weight of potassium hydroxide and sodium hydroxide was 5:1.
The amount of arsenic in the refined alloy was 0.02%, and the amount of dry granular skims was 9%.
The amount of tin in the alloy was 90%.
Example 3 The method of example 1 was again repeated, except that the relative weight of potassium hydroxide and sodium hydroxide was 3:1.
The amount of arsenic in the refined alloy was 0.01% by weight, and 9% of solid granular skim was obtained.
The amount of tin in the alloy was 90%.
Comparative Example Here, a tin and lead alloy having a composition similar to the alloy used in example 1 was melted and treated with sodium hydroxide.
The-amount of arsenic in the alloy after treatment was 0.2% by weight, and the amount of skim was 22%.
The amount of tin in the alloy was 72% The skim was produced in the form of a thickened melt.
Claims
1. A method of separating arsenic and tin, which comprises: agitating a molten mixture comprising arsenic and tin, together with sodium and potassium hydroxides; and skimming.
2. A method according to Claim 1, in which from 3 to 5 parts by weight of potassium are present to each part by weight of sodium.
3. A method according to Claim 1 or Claim 2, in which agitation is carried out at a temperature of from 400 to 5600C.
4. A method according to Claim 1, substantially as herein described with reference to any one of the foregoing examples.
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Separation of Arsenic and Tin The present invention relates to a method of removing arsenic from tin alloys. Arsenic has been removed from tin alloys by treatment with sodium hydroxide, but this does not work very well. We have now discovered a method of separation which is much more effective. The present invention consists in a method of separating arsenic and tin, which comprises: agitating a molten mixture comprising arsenic and tin, together with sodium and potassium hydroxide, preferably in the ratio from 3 to 5 parts by weight of potassium to 1 part by weight of sodium; and skimming. By means of this method it is possible to separate arsenic not only from alloys consisting solely of arsenic and tin, but also from more complicated alloys. Very high degrees of purification can be achieved by this method; the amount of arsenic in the refined tin can easily be as low as from 0.01 to 0.04%. Also, the amount of tin lost during the separation can be reduced by from 9 to 10% by use of the method of the invention. The skim that is produced by this method is dry and granular and free from mechanical inclusions of metal droplets. Such skims are easily conveyed elsewhere for subsequent treatment. The method of the invention may be carried out in the following way. A mixture of potassium and sodium hydroxide, preferably in a weight ratio of from 3 to 5 parts of potassium hydroxide to 1 part of sodium hydroxide is introduced into a molten alloy of tin and arsenic. Other metals, more usually non-ferrous metals, may of course be present in the alloy. This liquid is then agitated, for example by stirring, and preferably at a temperature of from 400 to 56O0C. The arsenic in the melt reacts with the alkalies, and the product passes into the skim. The skim may change from liquid to solid, possibly in the form of granules, and this depends on the relative amount of potassium and sodium hydroxides. The preferred relative amount of potassium and sodium hydroxides (3:1 to 5:1) leads to a skim that is strong, dry and contains no mechanical inclusions of melt droplets. These dry granular skims are then removed from the surface of the liquid. The amount of hydroxides consumed during the method of the invention will depend on the amount of arsenic present in the original mixture. The invention is further illustrated by the following examples Example 1 A tin and lead alloy containing 0.45% by weight of arsenic was treated by stirring it at a temperature of 500 C in the presence of a mixture of 4 parts by weight of potassium hydroxide and 1 part by weight of sodium hydroxide. The amount of arsenic in the refined alloy was 0.1% by weight. The skim, which amounted to 6.5% by weight of the total amount of material, was obtained in the form of solid granules. The amount of tin in the alloy was 93.5%. Example 2 This was carried out as in example 1, but the relative weight of potassium hydroxide and sodium hydroxide was 5:1. The amount of arsenic in the refined alloy was 0.02%, and the amount of dry granular skims was 9%. The amount of tin in the alloy was 90%. Example 3 The method of example 1 was again repeated, except that the relative weight of potassium hydroxide and sodium hydroxide was 3:1. The amount of arsenic in the refined alloy was 0.01% by weight, and 9% of solid granular skim was obtained. The amount of tin in the alloy was 90%. Comparative Example Here, a tin and lead alloy having a composition similar to the alloy used in example 1 was melted and treated with sodium hydroxide. The-amount of arsenic in the alloy after treatment was 0.2% by weight, and the amount of skim was 22%. The amount of tin in the alloy was 72% The skim was produced in the form of a thickened melt. Claims
1. A method of separating arsenic and tin, which comprises: agitating a molten mixture comprising arsenic and tin, together with sodium and potassium hydroxides; and skimming.
2. A method according to Claim 1, in which from 3 to 5 parts by weight of potassium are present to each part by weight of sodium.
3. A method according to Claim 1 or Claim 2, in which agitation is carried out at a temperature of from 400 to 5600C.
4. A method according to Claim 1, substantially as herein described with reference to any one of the foregoing examples.
GB7846485A 1978-11-29 1978-11-29 Separation of arsenic from tin Expired GB2036801B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB7846485A GB2036801B (en) 1978-11-29 1978-11-29 Separation of arsenic from tin

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB7846485A GB2036801B (en) 1978-11-29 1978-11-29 Separation of arsenic from tin

Publications (2)

Publication Number Publication Date
GB2036801A true GB2036801A (en) 1980-07-02
GB2036801B GB2036801B (en) 1983-05-11

Family

ID=10501395

Family Applications (1)

Application Number Title Priority Date Filing Date
GB7846485A Expired GB2036801B (en) 1978-11-29 1978-11-29 Separation of arsenic from tin

Country Status (1)

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GB (1) GB2036801B (en)

Also Published As

Publication number Publication date
GB2036801B (en) 1983-05-11

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