JPH06306500A - Method for judging progress of oxidation reaction - Google Patents

Abstract

PURPOSE:To rapidly and conveniently judge the progress of an oxidation reaction at the time of recovering noble metal from noble lead. CONSTITUTION:The m.p. of a sampled metal is measured, and the noble metal content of the sampled metal is obtained from the measured m.p. and the relation between the previously obtained m.p. of the metal and the noble metal grade in the metal, and the progress of the oxidation reaction is judged therefrom. The end point of the oxidation and refining reaction is extremely easily and rapidly obtained in this way.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a precious metal-containing lead obtained by treating slime generated by electrolytic refining of copper and lead, by removing lead and other impurity elements into slag by oxidation or volatilization to remove gold and gold. It relates to a method of recovering silver.

[0002]

In the dry smelting of copper or copper concentrate, precious metals in ores and solvents are absorbed by crude copper and crude lead and finally concentrated in anode slime produced in electrolytic refining. Then, the noble metal is recovered from the noble metal-containing lead (hereinafter referred to as "noble lead") obtained from this anode slime.

In this recovery, when the raw material is copper electrolytic slime, the slime is sulphated and roasted, extracted with water to separate copper, and the resulting residue is oxidatively roasted to volatilize and remove selenium, Next, the obtained calcined product and a reducing agent are mixed, heated and dissolved to concentrate the noble metal in lead to obtain noble lead, and the noble metal is treated to recover the noble metal. When the raw material is lead electrolytic slime, the slime is directly melted to concentrate the precious metal in lead to obtain precious lead, and the precious lead is treated to recover the precious metal.
To recover the noble metal from the noble lead, the noble lead is heated and melted to form a melt, and air is blown to the melt to oxidize or volatilize lead and other impurities to remove them. Conventionally, this oxidization removal is performed using a reverberatory furnace called a weight separating furnace.

In order to achieve the further reduction in manufacturing cost required in recent years, it is not always sufficient to improve the operating method using this reverberatory furnace type centralization furnace, and therefore the upper blowing rotary furnace ( It has been attempted to further increase the oxidation efficiency by using (TBRC) or by blowing oxygen from the bottom of the melt using a special lance.

Whichever method is adopted, as a reaction, each element in the noble lead is oxidized in the order in which it is easily oxidized, volatilizes, or is separated and removed from the metal as slag.
Depending on the composition of the noble lead to be treated, the slag is discharged to the outside of the furnace to maintain the reactivity after the oxidation reaction progresses to some extent, or the noble lead is additionally charged after the slag is discharged to the outside of the furnace. To improve the treatment efficiency, or to discharge the slag out of the furnace to remove the tellurium, add an alkali metal compound or an alkaline earth metal compound into the furnace, or accelerate the removal of copper. The slag is discharged outside the furnace, and then lead is additionally charged into the furnace.

By the way, it is indispensable to accurately grasp the progress of the oxidation reaction in order to efficiently carry out each operation such as discharging the slag during the reaction to the outside of the furnace. In addition, the noble metal quality in the metal becomes extremely high at the end of the oxidation reaction, and the noble metal quality in the slag changes drastically.
Therefore, if the determination of the end point of the reaction, that is, the determination of the end point is erroneous, for example, if the oxidation is excessive, the precious metal migrates into the slag, increasing the loss of the precious metal, for example, in the case of insufficient oxidation, subsequent electrolytic refining of silver. Occasionally, slimes and the like occur frequently, which causes trouble. Therefore, how to accurately determine the end point of the reaction is a very important problem.

Conventionally, the following method has been adopted to estimate or measure the progress of this reaction. (1) The oxygen efficiency is evaluated based on the past operation results, and the progress of the reaction is estimated from the air flow rate and the expected oxygen efficiency. (2) Estimate from the generation rate of slag. This method is based on the phenomenon that when operating under constant oxidation conditions, the rate of slag formation increases or decreases depending on the type of element that is oxidized in a certain reaction stage. (3) The quality of the generated slag is estimated from properties such as fluidity and color. (4) A metal sample is taken, its color and properties are observed, and the composition is estimated. (5) A metal sample is taken and analyzed.

Among these methods, the method (1) has a problem that the end point estimated by the method does not coincide with the actual reaction end point due to variations in the oxidation efficiency.
The methods (3) and (4) have a problem that skill is required, and the method (5) has a problem that it takes too much time and is not suitable for on-site operation management.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method capable of quickly and simply determining the progress of an oxidation reaction when recovering a noble metal from noble lead.

[0010]

As a result of various studies to solve the above-mentioned problems, the present inventors have found that there is a clear relationship between the metal composition in the melt and the melting point, and the present invention has led to the present invention. It was That is, the method of the present invention for solving the above problems, in the method of recovering a noble metal from noble lead, the melting point of the sample metal obtained by sampling is measured, and the obtained melting point and the melting point of the metal obtained in advance. The ratio of the noble metal in the sample metal is obtained by using the relationship with the quality of the noble metal in the metal.

[0011]

In the method of the present invention, the melting points of metals are obtained in advance by using samples having different noble metal grades. For example, FIG. 1 shows Ag 25-32 wt%, Au 1-3 wt%, Bi
20-30% by weight, Pb10-15% by weight, Sb10-20% by weight,
350 kg of synthetic noble lead of 5 to 10% by weight of Te is charged into a reverberatory furnace, heated and melted, and air is maintained at 120 Nm ³ while maintaining the temperature at 1050 ° C
It shows the relationship between the melting point of precious metal (Au + Ag) and the melting point of the metal obtained by sampling the appropriately generated metal while spraying it on the surface of the melt at a ratio of / h, and It shows that there is a good correlation between them.

By using the correlation shown in FIG. 1 as a calibration curve, it is possible to determine the Au + Ag quality in the metal by determining the melting point of the metal. The amount of other noble metals in the noble lead, such as Pt and Pd, is smaller than that of Au and Ag, and its proportion to Au and Ag is less changed, and the amount of noble metal in the noble lead is increased by the method of the present invention. Has almost no effect on the quantification result of.

When the correlation between the melting point of the metal and the quality of the noble metal is obtained in advance, it is preferable that the melting point measuring method adopted is the same as the method of measuring the actual melting point of the sample.

[0014]

EXAMPLES Next, examples of the present invention will be described. (Example 1) Au, Ag, Pd, and Pt as the noble metals were 28.1% in total, Bi was 20.0%, Cu was 9.0%, and Te was 6.2.
%, Pb 12.0%, Sb 17.0% noble lead 2t
Was charged into a reverberatory furnace with a volume of 0.25 m ³ and a surface area of molten metal of 1.69 m ² .
It was melted by heating using a heavy oil burner. Two hours after the start of heating (start of operation), the noble lead was completely melted. At this time, the melting point of the metal was measured using a composite combination manufactured by Yamazato Electronite Co., and an analysis sample was collected. As a result, the melting point of the metal was 411 ° C, the total quality of the precious metals was 30.5%, and the S
b is 18.6%, Pb is 12.6%, Bi is 9.8%, Te is 6.2.
%, Cu was 9.8%. The value of this noble metal grade was almost the same as 30% obtained from FIG.

After that, the air is blown from the top blowing lance at 15 Nm ³ / min.
The oxidative purification was started by spraying on the surface of the melt at a ratio of. Rubbing the floating debris generated by oxidation refining outside the furnace at any time,
200-400 kg of noble lead was additionally charged every hour, and the produced Bi dense material was discharged out of the furnace. The volatile matter generated by the reaction was collected using a bag filter.

Generation of volatiles decreased after 15 hours from the start of the operation. Therefore, the melting point was measured and an analytical sample was taken in the same manner as above. At this point, the melting point of the metal is 235 ° C, the total quality of precious metals is 46.7%, Sb is 0.5%, Pb is 2.5%.
%, Bi was 10.1%, Te was 6.4%, Cu was 10.1%, and it was judged that Sb and Pb were almost removed. By the way, when the removal rates of Sb and Pb were calculated, each was 95%.
It was above 85%. The value of this noble metal grade was almost the same as 45% obtained from FIG.

Thereafter, the same operation was continued, and the melting point of the metal 31 hours after the start of operation was measured in the same manner as above. At this point, the melting point of the metal is 802 ° C, the total quality of precious metals is 75.6%, Sb is <0.1%, Pb is 0.5%, Bi is
The content was 6.3%, Te was 9.9%, and Cu was 6.3%. The value of this noble metal quality was almost the same as 76% obtained from FIG.

After 39 hours from the start of operation, the amount of dense metal produced per unit time decreased, and it became impossible to additionally charge precious lead. The amount of precious lead additionally charged up to this point is 5.4t.
It was. The melting point of the metal at this point was measured in the same manner as above. As a result, the melting point of the metal is 850 ° C, the total quality of precious metals is 85.7%, Sb is <0.1%, Pb is 0.
2%, Bi 0.8%, Te 9.0%, Cu 4.0%,
It was found that Bi was almost removed at this point.
The value of this noble metal grade was almost the same as 84% obtained from FIG.

Next, to remove Te, 20 kg of soda ash
Each time, it was charged 10 times into the furnace, and the oxidation was continued while removing the generated soda lice outside the furnace each time. After the start of operation
The melting point of the metal was measured at 54 hours in the same manner as above. As a result, the melting point of the metal was 938 ° C, the total grade of precious metals was 97.0%, Sb <0.1%, Pb 0.14%, Bi 0.8.
%, Te was 0.6%, Cu was 2.0%, and the color of the sample was red. The value of the noble metal quality was almost the same as 96% obtained from FIG.

Finally, in order to remove Cu remaining in the metal, the temperature of the melt was set to 1030 ° C., 300 kg of Pb was charged into the furnace, and the slag produced was removed outside the furnace to continue the oxidative refining. . The melting point of the metal was measured 62 hours after the start of operation in the same manner as above. As a result, the melting point of the metal was 958 ° C, the total quality of precious metals was 99.2%, Sb was <0.1%, Pb was
<0.1%, Bi: 0.3%, Te: <0.1%, Cu: 0.5%, which means that Cu removal is completed. In addition,
The value of this noble metal grade was almost the same as 99% obtained from FIG.

As can be seen from the above results, according to the method of the present invention, the end point of the reaction can be easily obtained by measuring the melting point of the metal.

[0022]

According to the method of the present invention, the end point of the oxidative purification reaction can be determined extremely easily and quickly. Then, by using this method, it becomes easy to optimize the operation.

[Brief description of drawings]

1] Melting point and Au + A of metal obtained by using synthetic noble lead
It is a relationship diagram with g quality.

Claims (1)

[Claims] 1. A method for recovering precious metal from precious lead, comprising:
Measure the melting point of the sample metal obtained by sampling,
A method for judging the degree of progress of an oxidation reaction, characterized in that a ratio of a noble metal in a sample metal is obtained by using the obtained melting point and a previously obtained relation between the melting point of the metal and the quality of the noble metal in the metal.