JPS5928540A - Bismuth concentration method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for concentrating bismuth. More specifically, the present invention relates to a method for efficiently concentrating bismuth from materials other than bismuth, which mainly consist of bismuth oxides, which are generated in the silver separation step for completely treating copper electrolytic anode slime or lead electrolytic anode slime.

Since precious metals are contained in the anode slime of steel heavy inn or lead electrolysis, in order to recover all of them, all precious metals are normally absorbed into the ship +0! : Noble lead is melted and oxidized in a total silvering furnace, and bismuth and other impurities containing lead f10 are removed in the form of a total oxide, so-called midda, to obtain crude silver, which is then electrolytically refined. .

When the bismuth content in the noble lead is high, the Mitsuda removed in the splitting furnace initially produces lead Mitsuda whose main component is lead due to the difference in affinity for oxygen between lead and bismuth, but it continues to oxidize. and bismuth mitsuda, whose main component is bismuth. Furthermore, when the metal from which the lead in noble lead has been removed by chlorination is processed in a silver separation furnace, bismuth Mitsuda is generally obtained because the amount of lead and metal is reduced.

In order to recover bismuth from this bismuth mitsuda,
In addition to bismuth, it also contains silver, copper, lead, tellurium, etc., so it is generally dissolved by adding a reducing agent to remove most of the impurities and recover the valuables as crude bismuth. However, the impurities contained in this crude bismuth vary widely depending on the raw materials, and have a composition as shown in Table 1, for example.

1st Table 11i Ag Pb Sb Cu Te49.3 9,
8 18.8 9.6 8.5 2.9 Weight ratio There are known dry refining methods and electrolytic refining methods for producing highly pure bismuth metal from such crude bismuth metal. In the electrolytic refining method, the metal is generally melted in advance, the antimony is oxidized and volatilized by blowing air into the molten metal, sulfur and caustic soda gold are added to decopper, and this is cast into an anode and electrolyzed. Although purification is carried out, the electrodeposited material must be remelted for further purification, and the equipment and processes, such as treatment of the electrolyte, are extremely complicated, and the amount of work-in-progress bismuth is extremely large. In addition, when applying the dry refining method, generally, in the same manner as described for the electrolytic refining method, de-andemo/decopper is first removed, then metallic zinc is added, slowly cooled with stirring, and drossed to combine the silver with the zinc. To remove it as a high melting point intermetallic compound, then raise the temperature and blow chlorine gas into the solution to remove zinc and lead as chloride dross, and further remove trace amounts of AS + Te + S b + Pb, etc. Caustic soda and powdered sulfur, and caustic soda and saltpeter are used. When carrying out all of these methods, it is necessary to change the reaction container for each step, and the pump for transferring containers is also used to prevent contamination with impurities. To prevent this, separate devices are required for each step, and temperature control in each step is complicated and requires high precision.Furthermore, when removing impurities, a large amount of bismuth is entrained, resulting in a low yield.

An object of the present invention is to provide a method for concentrating bismuth that eliminates the above-mentioned drawbacks, obtains crude bismuth metal with few impurities, and allows efficient purification.

The inventors of this application focused on the fact that bismuth is a metal with an extremely low melting point of 271°C9, and that the melting point drops even further when alloyed with lead, and as a result of various studies, the content of impurities has been reduced. By slow cooling in a large amount of crude bismuth gold container, metal impurities with a high melting point are solidified first, and bismuth with a low proportion of impurities can be concentrated in the unsolidified content, so all of this can be separated and recovered. The present invention is characterized in that the entire crude bismuth metal is heated to a temperature of 250°C from its solidification initiation temperature.
After cooling slowly at a cooling rate of 200°C/H or less, all unsolidified alloy is separated and recovered.

The present invention will be explained in detail below. The bismuth mitsuda eluted from the silver fractionating furnace is used as a reducing agent in the melting furnace.
When steel scrap is added and sulfide ore is added to recover the copper content as a glue and reduced and melted, lead and silver are produced with bismuth as the main component.

Crude bismuth metal containing antimony, kake, tellurium, etc. as impurities, sulfurized metal mainly composed of copper and lead, and slag containing antimony as an oxide are produced, and when left in the furnace, specific gravity difference occurs. The surface is more slag, dirt,
The coarse metal is separated into layers, which are then poured to discharge most of the slag and glue.Finally, the coarse metal in the furnace is discharged into a container and slowly cooled. As shown in Figures 1 and 2, it is best to use a container for slow cooling that is made of iron and has a lining on the inside to provide heat retention.The thickness of the lining can be increased as necessary. , and an auxiliary heating metal to maintain the desired cooling rate.

After the crude metal is transferred to an annealing container, it hardly solidifies at a temperature close to 600℃, and as shown in the figure, clay 5 is placed on an iron rod 4 with a teno ξ- attached to the diagonal part 3 of an annealing container 1. The thinly lined tube was inserted so that the entire upper end was exposed to the outside of the molten metal, and then slowly cooled to about 250°C at a cooling rate of 00°C/11 or less. The slow cooling may be performed substantially from the solidification start temperature of the crude metal, and it differs slightly depending on the composition of the crude metal. When slowly cooled, it solidifies from the periphery and surface of the container, leaving an unsolidified portion 6 inside, so when it reaches 250°C, pull out the iron rod 4 completely, and a cavity with the same shape as the iron rod will be created in the solidified portion, and the hole in the hole will be the unsolidified portion. 6, the bismuth-concentrated metal can be easily recovered by tilting the slow cooling capacity aX- and letting the unsolidified metal flow out. Cooling rate during slow cooling is set to 2.
The reason for setting the temperature to 00° C. 711 or less is that if the speed is higher than this, the distribution rate of bismuth to the unsolidified portion will be poor, and the overall bismuth recovery efficiency will be poor.

The parts that solidified during slow cooling were bismuth, lead, and silver.

When copper, antimony, and tellurium have a high total distribution ratio and repeat the reduction and melting process of bismuth Mitsuda again, silver mainly enters coarse silver, antimony enters slag, and copper and tellurium enter glue, so bismuth becomes easy. The concentrated portion of unsolidified bismuth can be purified according to the conventional dry refining method to obtain high-purity bismuth, but if it is processed according to the method of the present invention, the content of impurities during dry refining will be lower than that of the conventional method. The amount of bismuth is much smaller than that of the conventional method), making it easy to purify, and the amount of bismuth lost along with it is small, making it possible to recover bismuth efficiently.

Examples will be described below.

Example 1 Crude bismuth metal obtained by reducing and melting bismuth Mitsuda was discharged from the furnace at 1000°C and placed in a slow cooling container at 1000°C.
I accepted ky. The analytical values for crude metals are shown in Table 1. Even when this rough metal was cooled to 600°C, the surface was still hardly solidified. At this point, insert an iron rod to remove unsolidified material, and then heat the temperature at 100°C until 250°C.
When the steel bar was slowly cooled at a ratio of /II, the iron bar was completely pulled out, and the unsolidified portion was discharged, a metal of 400 ky was obtained. The analysis values for unsolidified metal and solidified metal are shown in Table 2, and the distribution ratio is shown in Table 3.

Table 2 Analysis weight Bi Ag Pb Sb Ou T
eUnsolidified metal 74.3 4,4 19.6 1
．． 0 0.4 0.2 Solidified metal 32,6 13.
1 18,2 15,2 13.9 4.7 Table 3 Distribution ratio Bi Ag T'b Sb Cu Te Unsolidified metal 60.31 18.30 4179 4.
20 188 2.76 solidified metal 39.6981
．． 7058.2195.8098.1297.24 As is clear from the results in the table above, the distribution of impurities other than Pb in the unsolidified metal is much smaller than in the solidified metal, and bismuth is concentrated.

Example 2 Crude bismuth metal was obtained by melting substantially the same raw material as in Example 1 under reduced pressure, and the mixture was slowly cooled in a slow cooling container. In this example, the distribution ratio of I31 to unsolidified metal and solidified metal was completely investigated by changing the cooling rate, and the results shown in Table 4 were 14I.

Table 4: As the cooling rate increases, the BiO content in the unsolidified metal decreases, and the efficiency decreases due to fewer vehicles being distributed, so the cooling rate is 200℃.
/II or less is desirable.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a slow cooling container used in the method of the invention. FIG. 2 is a plan view thereof. DESCRIPTION OF SYMBOLS 1... Iron container, 2... Lining, 3... Inclined part, 4... Iron bar, 5... Clay lining, 6...
Unsolidified portion. #/figure

Claims (1)

[Claims] To separate and recover all of the unsolidified alloy from the solidification start temperature to 250'C, which contains bismuth as the main component obtained by total reduction melting of bismuth misoda, and which contains all metals having a melting point higher than bismuth. A method for concentrating bismuth, characterized by: