JPS58126942A - Manufacture of thallium - Google Patents

Abstract

PURPOSE:To manufacture metallic Tl of high purity by adding NaCl to a slurry obtd. by leaching of Tl-contg. substance using SO2, and after filtering, recovering Tl slag containing TlCl, filtering after making the Tl slag basic, and performing cememtation using zinc plate under an acidic condition. CONSTITUTION:Electrolytic solution of lead, and clean slag generally containing 10-20% Tl produced in refining of Cd and impurities such as Zn, Cd etc. is leached with SO2, and Tl contained is reduced from trivalent to monovalent and changed to water soluble. NaCl is then added to the leached slurry. After sufficiently agitating to change Tl to TlCl, it is filtered to separate into a filtrate containing impurities such as Mn etc. and Tl slag. Then, Tl slurry adjusted to above pH 9.0 by adding water and MaOH etc. is leached while agitating at room temperature -80 deg.C, for instance 60 deg.C. Selective leaching is performed restraining leaching of arsenic, zinc and Cd. The leach is filtered, and the filtrate is substituted using a zinc plate keeping the filtrate at pH 2-4. Metallic Tl of high purity is obtained through fine granular spongy Tl.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing high-purity metallic thallium from thallium-containing substances. 9 by wet processing including a displacement process using zinc plates.
9.999-grade high purity metal thallium manufacturing method. This method is an improvement of the thallium production method filed by the applicant on the same date, and is aimed at producing metallic thallium that is less likely to be contaminated with impurities than that obtained by the same method.

Depending on the source, thallium can be found in lead electrolytes, clean slag from cadmium smelting processes, zinc smelting smoke, and other residues and wastes from non-ferrous smelting processes, depending on their source.
Contains about 1. If thallium is left unrecovered from such thallium-containing materials, it will accumulate during circulation in the thallium Fi smelting system, and if the allowable limit is exceeded, it will have negative effects on various process steps. Not only that, but recently, special optical applications such as optical fibers and copier lenses, phototubes,
Thallium has come to be required for sealing in transistors and the like, and in this case, highly pure metallic thallium is particularly desired.

In this field, there are still few attempts to develop an industrial method for producing thallium from thallium-containing substances, and in particular, a method for producing high-purity metal talic^ has not been established. One of the proposed methods is, for example, the method disclosed in Japanese Patent Application Laid-Open No. 156941/1983. This method consists of two steps: (1) adding sodium sulfite as a reducing agent to the smelting intermediate containing pitthallium and dissolving it in a sulfuric acid solution, and (2) adding soda ash or potassium carbonate to this F solution to adjust the pH to 9 or higher. , a step of separating and removing the formed precipitate, and (c) further adding sulfuric acid to the P solution to adjust the pH to below 15, and adding zinc powder to cement it! 99.
．． High purity all-grade thallium of 9911 or higher! It has been reported that scales are produced. However, since the above method uses zinc dust as a reducing agent for cementation, there is a risk that the zinc dust may be mixed into the product, and therefore it is not necessarily suitable as a method for producing high-purity metallic thallium. There is still room for improvement in impurity removal. Furthermore, when sulfite reduction was carried out, it was observed that a large amount of reddish-brown precipitate was generated upon substitution with zinc, and that the spongthallium formed was likely to crumble into fine particles.

Therefore, in the application filed on the same day, the present inventor proposed a method for producing metallic thallium that does not exhibit the above-mentioned drawbacks. This method is as follows: (a) Thallium-containing substances tS Ox are leached and S
A step of producing an Ot leaching slurry (Sow leaching step) and (b) adding pH 1 to the SOt leaching slurry. (c) a step of filtering the alkali-added slurry (filtration step); and (d) adding sulfuric acid and peroxide to the filtrate. Add hydrogen, pH = 2 ~
a step of cementing carbon using a zinc plate in S (zinc plate replacement step); and a step of melting the resulting spongthallium using a molten sodium hydroxide bath (melting step). The main points are that the use of a zinc plate in the zinc replacement process eliminates the problem of entrainment of zinc dust, enables the removal of various impurities, and does not produce reddish-brown precipitates in the zinc replacement process. Sponge thallium could be produced, and as a result, metallic thallium with a quality of 99999% and good cohesiveness could be produced.

However, the present inventor has discovered that in the above method, SO1
After the leaching stage and before the Tl leaching/alkali neutralization stage, SO! By adding sodium chloride to the leaching slurry?
! ? ? ? - Discovered the ability to produce thallium metal in a more stable manner. Furthermore, it was confirmed that by pre-adding sodium chloride, reddish-brown precipitates did not occur during the zinc plate replacement stage even without the addition of hydrogen peroxide. In the above method, hydrogen peroxide was added at the zinc plate replacement step.
It was discovered that reddish-brown precipitate was caused by nithionic acid (stos) produced when SOl was injected excessively during the leaching stage, and this problem was solved by oxidizing nithionic acid to SOa. It was something. However, SO! By pre-adding sodium chloride to the leaching slurry and then carrying out the alkali addition and subsequent steps to the separated thallium slag, very small amounts of nithionic acid are carried into the leaching solution, and therefore no excess is added during the zinc plate replacement step. Addition of hydrogen oxide becomes unnecessary. Furthermore, the preliminary addition of sodium chloride is effective in completely removing manganese, which sometimes remains in trace amounts in the produced metal thallium. Recovery of thallium slag by preliminary addition of sodium chloride and subsequent removal of the remaining liquid may also be beneficial in that other impurities can be separated and removed at an early stage.

Thus, in the steps (a) to (e) above, the present invention adds sodium chloride to SOl and the leaching slurry between (amount) (a) and (b) to produce thallium chloride. , intervening a step of recovering thallium slag containing thallium dichloride through filtration, subjecting the thallium slag to TI leaching and alkali neutralization steps, and peroxidation in the zinc plate replacement step of (if)). It is characterized by the addition of hydrogen.

As stated in the above application, if the starting thallium-containing material contains lead, after the filtration step, the filtrate contains barium carbonate (Ba carbonate).
A deleading step can be incorporated to remove precipitates by adding cos) and sulfur.

Hereinafter, the present invention will be explained in detail with reference to drawing flow sheets.

As mentioned above, the thallium-containing substances that are the starting materials of the present invention are intermediates and residues produced in the nonferrous metal smelting process, such as lead electrolyte and clean slag produced in the cadmium smelting process. However, here we will proceed with the explanation using clean slag as an example. Clean slag refers to cadmium-containing raw materials such as cottle dust and smoke ash in cadmium smelting, which are sulfated and roasted and then leached with warm water, and the leachate is then poured into a purification tank! It refers to the residue obtained by solid-liquid separation with the addition of potassium peroxide, zinc oxide, etc. The separated liquid is called the clean liquid and is used in the cadmium ingot manufacturing process, and the clean slag is repeated in the conventional process, but here it is used as a starting material for the metal thallium manufacturing process. . Clean slag generally contains 10-20% thallium, as well as varying degrees of impurities such as zinc, cadmium, lead, arsenic, and manganese.

The clean slag is first subjected to an 80W leaching treatment.

The Sow leaching process itself is known, and ■ 51! It reduces thallium, which exists in the form of 11iK, to make it water-soluble.

The 80w leach slurry is then added with sodium chloride and stirred thoroughly. This results in thallium chloride ('l
'lcl) is generated. Sodium chloride is SO1&
Thallium in the output slurry is converted into ttX thallium.
It is added in a stoichiometric amount or slightly in winter. After sufficient reaction,
It is separated into filtrate and thallium slag by filtration. Through this treatment, impurities including manganese are transferred to the filtrate as described above, and the subsequent treatment of the thallium slag can be carried out suitably.

An important point of the present invention is to separate and remove impurities as early as possible in the process.

The photothallium slag thus produced is repulped by adding storage slag and water as needed, and then sent to the thallium leaching and alkali neutralization stage. Thallium slag slurry is
In the leaching tank, it undergoes an alkaline leaching operation above p[z'lo. The leaching operation is carried out by adding sodium hydroxide, potassium hydroxide, and sodium carbonate to a pH of 90 or higher, preferably around 11, and then cooling to room temperature to 80°C, for example 60°C, with stirring for an appropriate period of time. . In this leaching reaction, zinc and cadmium in the 80 m leaching slurry are converted into hydroxides to suppress leaching, and arsenic is adsorbed to these hydroxides, so that leaching of arsenic is effectively inhibited. In this way, it is beneficial at the alkaline point. By preliminarily removing arsenic from %, -m*
This is extremely useful in the demolition work because it prevents the generation of arsine gas ()tsAI)O during the oxidation stage. te,
Mixed alkali of sodium hydroxide and sodium carbonate (
For example, if a ratio of 1:1) is used, sedimentation and filtration properties will be extremely good.

The alkali-neutralized leachate is thus sent to the filtration stage after thallium leaching is completed. Filtration is carried out by natural sedimentation or by using a filter press. It can be carried out in two stages: normal filtration and clarifying filtration. Furthermore, it has been found that performing sedimentation separation with a settling time of 1 to 2 hours and performing clarification filtration on the supernatant liquid is more beneficial for filtration of thallium slag.

If the leachate after filtration or the starting material contains lead, it is deleaded. The delead treatment is carried out by adding 2 to 51 units of barium carbonate to the leachate and adjusting the pH of the liquid to 1-5 with sulfuric acid. Deleading by adding barium carbonate utilizes the phenomenon in which lead co-precipitates when barium sulfate precipitates are formed. Therefore, sufficient contact with lead is required when barium sulfate precipitates. It is necessary to sufficiently stir the liquid to sufficiently disperse barium carbonate in the liquid.

After deleading, the filtrate obtained by filtration is subjected to a zinc plate replacement step to generate spongthallium. Sulfuric acid is added and a displacement step is carried out using a cementitious 5-f reaction using a zinc plate while maintaining the pH at 5-4. As mentioned above, in the case of the leachate obtained by leaching thallium slag, unlike the case of the leachate obtained by leaching SO1 leaching slurry, sulfur or Reddish-brown precipitates caused by sulfides do not occur. When a mackerel brown precipitate is formed, spongthallium becomes finely granular, and when it is melted in a sodium hydroxide bath and then coagulated, the agglomeration of metallic sodium is poor and its surface becomes blackish.

In the present invention, excess 080. Since the amount of nithionic acid brought in due to blowing is extremely reduced by pretreatment of 9 um chloride, such consideration reduces construction costs! It is. In addition, when hydrogen peroxide is added, the pH of the liquid at the beginning of the replacement changes.
However, in the present invention, such problems do not occur.

In the present invention, since the cement/take sintering reaction is successfully carried out using a zinc plate, there is no possibility of the problem of zinc dust entrainment seen in the prior art.

The generated sponge thallium is pressed and dehydrated! It is melt-treated by placing it in a molten hydroxide bath at 150°C.

Through this melting process, the remaining impurities of the zhζCd%pb cape are transferred into the soda slag, and metallic thallium of even higher purity is obtained. Through this treatment, metallic thallium with a grade of 999991% is obtained. In order to prevent thallium from being lost into the slag due to oxidation, it is necessary to completely cover the sponge thallium with sodium hydroxide.

Refined molten metal thallium is cast as thallium bullion, which has good cohesive properties without entrainment of zinc dust.
9.9? It has a grade of 9-, and can be suitably used for sealing applications in the field of special optical glasses, phototubes, and transistors, for which demand has been increasing recently.

In this way, the present invention overcomes the nine drawbacks recognized in connection with the prior art, and also establishes a method for industrially stably producing 99.999% high purity thallium. It is meaningful.

Next, examples of the present invention will be described.

Example: 80! by blowing SOt gas into the clean slag! A leaching slurry was prepared, sodium chloride was added thereto in a slightly smaller amount than the chemical commercial amount, and the resulting slurry was filtered to recover 60# (dry amount) of thallium slag. The composition of the thallium slag was as follows.

After adding 4 tons of water and repulping it, it was heated to 60°C, and NlOH and Nap Co1 were added at a weight ratio of 1:1.
The mixture was stirred for 1 hour at 11 H. NaOH and Net
The amount of Gos used was 111 j/l thallium slag, respectively. Thereafter, filtration was performed to obtain 41 tons of leachate. The composition of the leachate was as follows.

Leachate (4,1 t) Next, half of this leachate, 2 tons, was subjected to delead treatment. For deleading treatment, the leachate is heated to 60°C, and the Ba COH pipe 51
In addition, the pH was maintained at 3 by adding a mimic acid, and the test was carried out with sufficient stirring. The treatment time was 2 maki intervals. In addition to a decrease in the amount of lead, a decrease in the amount of arsenic was also observed.

2 cc of sulfuric acid was added to the deleaded solution after filtration, and at pH=5, a replacement step with cementation was performed using a zinc plate. The liquid temperature was kept at room temperature and the reaction was carried out for 5 hours while stirring. No reddish-brown precipitate was observed during substitution, and the spongthallium produced was of good quality. The analysis results of the obtained spongthallium are shown below.

Sponge T1 Next, the sponge thallium was press-dehydrated and then placed in a molten NaOH (1o ag) bath at 550°C for 50 minutes. After 30 minutes of melting, the mixture was cooled and solidified with NaOH outside the furnace to obtain metal thallium.

What is the quality of the metal thallium obtained? House! 9! I'm vomiting
! Ivy. The analysis results are shown below.

Metal Tl In this way, there is no need to worry about entrainment of zinc dust, no reddish brown precipitate occurs during substitution, and metal thallium has good flocculation properties. ! ? ?
? -obtained with high purity.

[Brief explanation of the drawing]

The drawing is a 70-sheet of the method of the invention. Kurahashi Akira) Procedural Amendment April 12, 1980 Commissioner of the Japan Patent Office Shima 1) Indication of the Haruki Tono case 1981 Patent No. ys o s
Title of the bow invention Relationship to the case of the person amending the thallium production method Patent applicant name Name Japan Mining Co., Ltd. Agent 103 Address Oil and Fat Industry Hall, 3-13-11 Nihonbashi, Chuo-ku, Tokyo Telephone number: 273-6436; − Subject of amendment 1 −−゛− Contents of amendment As shown in the attached sheet, the specification of Patent @5.7-7505 will be amended as follows. t The scope of patent claims will be amended as follows. 1) (a) Thallium-containing substances are treated with SO2 leaching to
(b) adding sodium chloride to the S pseudo-leaching slurry to produce thallium chloride; and (c) recovering thallium slag containing thallium chloride by filtration; a step of adding an alkali to the thallium slag so that the pH becomes 9 or more; (2) a step of filtering the alkali-added thallium slag; (e) adding sulfuric acid to the casing after the filtration, A method for producing high-purity metallic thallium, comprising the steps of performing cementation using a zinc plate in steps 2 to 4, and (f) melting the produced sponge thallium using a molten sodium hydroxide bath. 2) (a) Thallium-containing substances are leached with SO□ and S
(b) adding sodium chloride to the S03 leaching slurry to produce thallium chloride, and recovering thallium slag containing thallium chloride by filtration; (c) adding to the thallium slag. (b) filtering the alkali-added thallium slag; (e) adding barium carbonate and sulfuric acid to the filtrate to remove precipitates; (f) Add sulfuric acid to the solution after removing the precipitate, and pH=! ~
4. A method for producing high-purity metallic thallium, comprising the steps of performing 7-mentesi carbonization using a zinc plate; . ” 2. Page 4, line 2, insert a “-” between “,” and “,”. 5. On page 5, correct the line ``2-3'' to read ``12-4''. 4 Page 7, line 2 “8!0＠” instead of “8!0＠
1"", and in the same line, 4th line rgoa-"J is corrected to r804'-J. -Page 1111, 7th line, insert "-" between "filter" and "press". Please correct melon page 12, line 5, ``S~4'' to ``2~4''. 7. Page 12, lines 14-15, "sodium" was changed to "thallium j", and line 17, "amount" and "chloride"
Insert "ga" between.

Claims (1)

[Claims] 1) (a) A thallium-containing substance is subjected to Soz leaching treatment to produce S
producing an Ox leaching slurry; and (b) l*s.
Adding sodium chloride to Ot leaching slurry to produce thallium chloride, and collecting thallium slag containing thallium sulfide through filtration; e→ Adding an alkali to the thallium slag so that p fl-9 or more (b) filtering the alkali-added thallium slag; and (e) adding KIR acid to the filtrate after the filtration and adjusting the pH to -2 to 5.
A method for producing high-purity metallic thallium, comprising the steps of: performing cementation using a zinc plate; and (f) melting the formed sponge thallium using a molten sodium hydroxide bath. 2)←) Thallium-containing substances are leached at 80w and SO
(b) adding sodium chloride to the SO snow leaching slurry to produce thallium chloride, and recovering thallium slag containing thallium chloride by filtration; a step of adding an alkali to the thallium slag so that the pH becomes 9 or higher; (b) a step of filtering the alkali-added thallium slag; and (e) adding barium carbonate and sulfuric acid to the filtrate to remove precipitates. (2) Adding sulfuric acid to the solution after removing the precipitate, and
A method for producing pure metallic thallium, which includes the steps of performing cementation using a zinc plate in steps 2 and 3, and (g) melting the produced sponge thallium using a molten sodium hydroxide bath.