CN-117568624-B - Bismuth purification method

CN117568624BCN 117568624 BCN117568624 BCN 117568624BCN-117568624-B

Abstract

A bismuth purification method for recovering bismuth from a liquid obtained by recovering a noble metal from copper electrolysis mud, comprising six steps, 1) a neutralization treatment step of adding an alkali to an acidic solution to adjust the pH to a range of 2.0 to 3.0, and then performing solid-liquid separation to obtain a neutralized filtrate and a neutralized precipitate, 2) an alkali leaching step of adding an alkali to the neutralized precipitate obtained in the neutralization treatment step to separate the neutralized filtrate and an alkali leaching residue, 3) a sulfuric acid leaching step of adding sulfuric acid to the alkali leaching residue to separate the neutralized precipitate and the sulfuric acid leaching residue, 4) a cooling step of cooling the sulfuric acid leaching solution obtained in the sulfuric acid leaching step to obtain bismuth sulfate crystals, 5) a bismuth oxidation step of adding an alkali to the bismuth sulfate crystals obtained in the cooling step to obtain bismuth oxide, and 6) an electrolysis step of adding an acid solution to the bismuth oxide obtained in the bismuth oxidation step to dissolve the bismuth oxide, and performing electrolytic extraction of the obtained solution to obtain metallic bismuth.

Inventors

TAKEYUKI HIROSHI
Earth extension
Nagakura Junyan
TAKEDA KOJI
ASANO TAKASHI

Assignees

住友金属矿山株式会社

Dates

Publication Date: 20260505
Application Date: 20170130

Claims (2)

1. A method for purifying bismuth, characterized in that, in the step of recovering copper by electrolytic purification of blister copper obtained by smelting a mineral containing copper, a noble metal, bismuth and an impurity, and then recovering noble metal from an electrolytic mud obtained by electrolytic purification by a wet method, an acidic solution obtained by recovering noble metal is subjected to the following step, wherein the impurity is one or more of iron, lead, arsenic and tellurium, 1) A neutralization treatment step of adding a base to the acidic solution, adjusting the pH to a range of 2.0 to 3.0, distributing impurities containing iron and antimony to a neutralization filtrate, and removing the impurities, and distributing bismuth and a part of the impurities to be recovered to a neutralization precipitate; 2) An alkaline leaching step of adding 1 to 5mol/L sodium hydroxide solution to the neutralized precipitate so that the slurry concentration becomes 10 to 100g/L, setting the reaction temperature to about 60 ℃, and removing impurities containing arsenic and chloride ions by partitioning them into a leachate so that the proportion of iron, lead and arsenic in the alkaline leaching residue becomes 50% or less, the molar ratio of arsenic to bismuth in the alkaline leaching residue becomes 0.1 or less, and the grade of chloride ions becomes 0.1% or less; 3) A washing step of adding water into the alkaline leaching residue to form a slurry state, and washing until the pH value is 2.5-3.5; 4) A sulfuric acid leaching step of adding sulfuric acid to the washed alkali leaching residue, separating the alkali leaching residue into a sulfuric acid leaching solution having a copper distribution ratio of 50% or more in the sulfuric acid leaching solution and a sulfuric acid leaching residue having reduced impurities, The sulfuric acid leaching process consists of leaching treatment in two stages of primary treatment and secondary treatment, The primary treatment is carried out to lead the sulfuric acid with the pH value of 0-3.5 to contact the washed alkali leaching residues to leach the leaching residues, the leaching residues are separated into primary leaching liquid and primary leaching residues, The secondary treatment enables sulfuric acid with the pH value less than 0 to contact the primary leaching residues, and the primary leaching residues are separated into secondary leaching liquid and secondary leaching residues; 5) A cooling step of cooling the secondary leachate obtained in the sulfuric acid leaching step to obtain bismuth sulfate crystals; 6) A bismuth oxidation step of adding a base to the bismuth sulfate crystals to obtain bismuth oxide; 7) And an electrolysis step of adding an acid solution to the bismuth oxide to dissolve the bismuth oxide, and performing electrowinning of the obtained solution to obtain metallic bismuth.
2. The method for purifying bismuth as claimed in claim 1, wherein the acid solution used in the electrolytic process is a silicofluoric acid-containing solution.

Description

Bismuth purification method The application is a divisional application of application No. 201780037819.7, the application No. 2017, 01, 30 and the application of the application named as a bismuth purification method. Technical Field The present invention relates to a method for purifying (refining) bismuth. More specifically, the present invention relates to a purification method for recovering bismuth as a valuable metal from copper electrolysis mud (electrolysis slime) produced in a copper electrolysis purification step. Background As a method for recovering copper from copper-containing ores, there is generally used a method in which a beneficiation process is performed on copper-containing ores to obtain copper concentrate after copper concentration, the copper concentrate is charged into a furnace and melted under high temperature conditions, such dry smelting is performed to obtain blister copper, the blister copper is immersed in an acidic sulfuric acid solution as an anode, an electric current is caused to flow between the anode and a cathode using a stainless steel plate or a copper plate immersed so as to face the anode, copper dissolved from the anode is selectively electrodeposited on the cathode, and such electrolytic purification is performed to obtain high-purity electrolytic copper. In addition to the target copper, the copper-containing ore often contains various components such as noble metals such as gold and silver, bismuth, arsenic, antimony, selenium, lead, iron, tellurium, and other valuable substances and impurities. These components are separated from copper as slag in the above-described dry smelting or as copper electromud deposited together with noble metals in the bottom of the electrolytic cell in electrolytic purification. Since the copper electrolysis sludge contains various components as described above, it is necessary to perform a treatment for purifying the sludge and recovering valuable substances as targets. There are known various methods for purifying the sludge, in which sulfuric acid is added to the copper electrolysis sludge, copper mixed with the copper electrolysis sludge is dissolved and removed, that is, a decoppering step is performed, the decoppered sludge obtained by decoppering is then charged into a furnace and heated to a high temperature to volatilize and separate selenium and antimony, oxidation is performed to separate lead in the form of oxides, and then the noble metal and bismuth are separated. Although the above method is suitable for treating a large amount of materials, it has problems such as increased efficiency in the treatment, because it requires a large-scale facility, requires a large energy cost for the treatment, and the step of recovering the noble metal is in the latter half of the process. In view of this, in recent years, the application of new treatment processes mainly using a wet method has been gradually started. These wet treatment processes are classified into the following two methods, in which selenium separation is performed by wet reduction or by baking. The first method is a method shown in non-patent document 1, patent document 1 or patent document 2. In these processes, sulfuric acid and oxygen are added to the copper electrolysis mud, and a portion of the tellurium, as well as copper, is leached under high temperature and pressure conditions. Then adding hydrochloric acid and hydrogen peroxide or chlorine into the leached residue to leach gold, platinum group elements, selenium and tellurium. Then, bis (2-butoxyethyl) ether (hereinafter referred to as DBC) as an organic extractant is mixed in the leachate to extract gold into the extractant, and the raffinate is reduced with sulfur dioxide to recover selenium, tellurium and platinum group elements. The mixture of selenium, tellurium and platinum group elements is distilled in a metallic state, whereby selenium, tellurium and platinum group elements are separated. For chlorine leaching residues, silver is leached by treatment with ammonia water, and silver is recovered from the leaching solution in powder form. The second method is a method shown in non-patent document 2. That is, the steps of removing copper and tellurium by pressure leaching the copper electrolysis mud with sulfuric acid are the same as those of the first method, but the residue is then mixed with sulfuric acid, and the mixture is calcined to volatilize and separate selenium, and at the same time, silver in the residue is converted into silver sulfate. Then, as for the sulfuric acid roasting residue, first, silver is leached with an aqueous solution of calcium nitrate, and then the leaching solution is electrolyzed to recover silver metal. Gold, platinum group, selenium, and residual tellurium are leached from the residue after silver leaching with hydrochloric acid and chlorine. The extraction of gold by mixing DBC in the leachate is based on the same principle as in the first method. Further, by su