CN111889697A

CN111889697A - Preparation method of high-purity gold

Info

Publication number: CN111889697A
Application number: CN202010743914.2A
Authority: CN
Inventors: 董海刚; 赵家春; 裴洪营; 崔浩; 吴跃东; 王钊; 童伟锋; 王亚雄; 吴晓峰; 戴华
Original assignee: Sino Platinum Metals Co Ltd
Current assignee: Sino Platinum Metals Co Ltd
Priority date: 2020-07-29
Filing date: 2020-07-29
Publication date: 2020-11-06

Abstract

The invention discloses a method for preparing high-purity precious metal for the electronic industry, in particular relates to a method for preparing high-purity gold, and belongs to the technical field of the electronic industry and high-purity precious metal materials. The preparation method of the invention is to carry out chlorination dissolution liquid preparation on the primary gold raw material, and adopts the process of combining neutralization precipitation, ion exchange and other impurity removal methods and selective liquid phase reduction to prepare the high-purity gold for the electronic industry. The method comprises the following steps: (1) dissolving and liquid making; (2) neutralizing, precipitating and removing impurities; (3) removing impurities by ion exchange; (4) liquid-phase reduction; (5) and (6) acid washing. The method has the advantages of simple process flow, easy implementation and mild preparation conditions, and the obtained gold has the purity of more than 99.999 percent and is suitable for being used as basic raw materials in the electronic industry, such as film materials of integrated circuits and semiconductor devices.

Description

Preparation method of high-purity gold

Technical Field

The invention relates to a method for preparing high-purity precious metal for the electronic industry, in particular to a method for preparing high-purity gold, and belongs to the technical field of the electronic industry and high-purity precious metal materials.

Background

High purity gold is an important film material in the electronics industry, such as integrated circuits, semiconductor devices, and the like. With the development of high-end integrated circuits, the purity of gold raw materials is required to be more than 99.999%.

At present, the preparation method of high-purity gold comprises an electrolytic method, a solvent extraction method, a chemical reduction method and the like.

In the literature, a pure gold starting sheet is used as a cathode, a raw material with the gold content of 95-99% is used as an anode plate, and the gold purity is over 99.997% through one-time gold electrolysis.

Yan Guo Xiang, etc. adopts electrolytic process to prepare high-purity gold, and its technological process is characterized by that the Au with grade greater than 99.9% is cast into anode plate, and is electrolyzed under a certain condition, so that the purity of the prepared high-purity gold is greater than 99.999%.

Jingtao et al developed a one-step high-purity gold production process to directly produce high-purity gold by electrolysis, and its purity is above 99.999%.

Research of Liu Wen and the like indicates that the high-purity gold is prepared by two-stage dissolution and two-stage reduction of gold-containing waste materials, and the total amount of impurity elements of the obtained high-purity gold is less than 0.001%.

In some researches, gold (Au 50-99.9%) is splashed into gold beads with the diameter less than 6mm, the gold beads are dissolved in aqua regia, an impurity removing agent S is added, and ascorbic acid or Na is used₂SO₃And reducing, washing and preparing the gold with the purity of 99.995%.

There is a document that a relatively pure chloroauric acid solution is prepared from 99.99% Au by aqua regia or electrolytic solution making method, ether is used for extraction, and after back extraction, sulfur dioxide is used for reduction to obtain high-purity Au more than or equal to 99.999%.

Chinese patent 201910119316.5 discloses a method for preparing high purity gold for electronic industry, which comprises dissolving aqua regia of gold ingot to make solution, adjusting pH, filtering with microporous membrane to obtain pure gold solution, adding reducing agent to reduce to obtain gold powder, and boiling and washing with dilute nitric acid and hydrofluoric acid to obtain high purity gold with purity of 99.999% and C, S content of less than 1 ppm.

The preparation methods of the high-purity gold generally have the problems of high production cost, environmental pollution, high requirements on raw materials and reagents, large fluctuation of impurity element content in products and the like, and the prepared high-purity gold often cannot meet the requirement of the electronic industry on the consistency of the quality stability of the products. The invention is particularly provided for solving the series of problems existing in the method.

Disclosure of Invention

The invention aims to provide a method for preparing high-purity gold for the electronic industry, which is different from the preparation method, the method has simple process, the purity of the obtained high-purity gold is more than 99.999 percent, and the method is suitable for the fields of the electronic industry, high-purity precious metal materials and the like.

The technical scheme for realizing the purpose is as follows:

a preparation method of high-purity gold comprises the following steps:

(1) dissolving and liquid making: dissolving crude gold (Au > 99.95%) in 3mol/L hydrochloric acid by introducing chlorine gas, heating, dissolving, and making a solution to obtain a gold solution A;

(2) neutralizing, precipitating and removing impurities: adjusting the pH value of the gold solution A obtained in the step (1) to 2-4, heating, keeping the temperature of the solution at 50-70 ℃, stirring at a constant temperature for 2-5 hours, and carrying out a neutralization precipitation reaction to separate impurities; after the reaction is finished, 1mg of flocculating agent is added into 1L of gold solution, and the mixture is continuously stirred for 0.5 to 1 hour; then standing for 12-24 h, and filtering and separating to obtain a gold solution B;

(3) removing impurities by ion exchange: further removing impurities from the gold solution B obtained in the step (2) through an ion exchange column filled with 001 x 7 type cation resin to obtain a gold solution C;

(4) liquid-phase reduction: adjusting the Au concentration of the gold solution C obtained in the step (3) to be not less than 5g/L, keeping the pH value of the solution to be 2-4 in the reaction process, stirring, and slowly adding superior pure hydrogen peroxide solutionLiquid, holding Au and H₂O₂Reducing at the temperature of 25-90 ℃ at the molar ratio of 1: 2-4, filtering, and washing to obtain sponge gold;

(5) acid washing: and (4) boiling and washing the sponge gold obtained in the step (4) for 0.5-1 h by respectively adopting nitric acid with the mass concentration of 20% and hydrochloric acid with the mass concentration of 10%, fully washing the sponge gold to be neutral by using deionized water, and drying the sponge gold in vacuum to obtain high-purity gold.

The principle of the preparation method of the invention is as follows:

after dissolving the crude gold, adjusting the pH value of the gold solution A to neutralize, precipitate and separate impurities, keeping the gold in the solution, adding a flocculating agent to facilitate the aggregation of fine impurity precipitates, solving the problem of penetration of fine impurities during filtering, realizing the separation of impurity elements and obtaining a gold solution B; removing impurities such as sodium ions from the gold solution by an ion exchange column to obtain a gold solution C; adding a reducing agent hydrogen peroxide solution into the gold solution C to selectively reduce gold, wherein the reducing agent does not bring impurities into the gold solution C, and other impurities are not reduced, so that the impurities are further separated; and removing the wrapped impurity elements from the reduced sponge through acid washing and deionized water washing to obtain the high-purity gold.

The preparation method of the invention has the following beneficial effects:

the method has the advantages of simple process flow, easy implementation and mild preparation conditions, and the obtained gold has the purity of more than 99.999 percent and is suitable for being used as basic raw materials in the electronic industry, such as important film materials of integrated circuits, semiconductor devices and the like.

Detailed Description

The examples used the following main raw materials, reagents and sources:

gold: from the precious platinum industries, Inc.;

hydrogen peroxide solution: premium grade, purchased from chemical corporation of west longland;

polyacrylamide: tianjin, Dingshengxin chemical Co., Ltd;

hydrochloric acid: the high-grade pure water is 36-38% in concentration and purchased from Xiong chemical corporation;

nitric acid: the high-grade pure water is 65-68% in concentration and purchased from Xiong chemical corporation;

sodium hydroxide: premium grade, purchased from chemical corporation of west longland;

chlorine gas: purchased from Kunming Meissel gas products, Inc.;

001 × 7 type cationic resin: purchased from gallery sendust chemical ltd;

and (3) gold purity determination: impurity content was analyzed using a uk NuAstrum Glow Discharge Mass Spectrometer (GDMS).

Example (b):

1) heating and dissolving gold (Au 99.95%) by using 3mol/L high-grade pure hydrochloric acid through chlorine to obtain a gold solution A;

2) adding sodium hydroxide solution of superior purity into the gold solution A until the pH value of the solution system is 3, heating to 70 ℃, stirring for reaction for 2h, adding the prepared polyacrylamide solution, continuously stirring for 0.5h, standing for 12h, filtering and separating to obtain gold solution B

3) Further removing impurities from the gold solution B through an ion exchange column filled with pretreated strong-acid 001 x 7 type cation resin to obtain a gold solution C;

4) adjusting the mass concentration of Au in the solution C to be 10g/L, keeping the pH value to be 4 in the reaction process, and reacting Au with H₂O₂Slowly adding a superior pure hydrogen peroxide solution with a molar ratio of 1:3, heating to 80 ℃, stirring, and fully reacting until the solution is colorless to obtain sponge gold;

5) and (3) boiling and washing the sponge gold for 1 hour by respectively adopting dilute nitric acid with the mass concentration of 20% and dilute hydrochloric acid with the mass concentration of 15%, then boiling and washing the sponge gold to be neutral by using deionized water, filtering, and drying in vacuum to obtain the high-purity gold.

The GDMS analysis of the high purity gold impurities prepared in this example is shown in table 1.

TABLE 1 GDMS analysis/ppm of high purity gold impurity elements

Na	0.82	Ni	0.005
				Ag	0.66	Pb	0.005
Cu	0.005	Pd	0.005
				Fe	0.29	Pt	0.03
Sb	0.005	Rh	0.005
				Al	0.03	Sn	0.005
As	0.01	Zn	0.002
				Be	0.005	Ir	0.005
Bi	0.13	Ti	0.02
				Cr	0.005	Cd	0.02
Ca	0.02	Mg	0.009
				Mn	0.05	Si	0.06

As can be seen from Table 1, the obtained high purity gold has an impurity content of less than 5ppm and a purity of more than 99.999%.

Claims

1. A preparation method of high-purity gold is characterized by comprising the following steps:

step (1), dissolving and liquid making: dissolving crude gold with more than 99.95% of Au in 3mol/L hydrochloric acid by introducing chlorine gas, heating and dissolving to prepare a solution, and obtaining a gold solution A;

and (2) neutralizing, precipitating and removing impurities: adjusting the pH value of the gold solution A obtained in the step (1) to 2-4, heating, keeping the temperature of the solution at 50-70 ℃, stirring at a constant temperature for 2-5 hours, and carrying out a neutralization precipitation reaction to separate impurities; after the reaction is finished, 1mg of flocculating agent is added into 1L of gold solution, and the mixture is continuously stirred for 0.5 to 1 hour; then standing for 12-24 h, and filtering and separating to obtain a gold solution B;

step (3), ion exchange impurity removal: further removing impurities from the gold solution B obtained in the step (2) through an ion exchange column filled with cation resin to obtain a gold solution C;

step (4), liquid phase reduction: adjusting the Au concentration of the gold solution C obtained in the step (3) to be not less than 5g/L, keeping the pH value of the solution to be 2-4 in the reaction process, stirring, slowly adding a superior pure hydrogen peroxide solution, and keeping Au and H₂O₂Reducing at the temperature of 25-90 ℃ at the molar ratio of 1: 2-4, filtering, and washing to obtain sponge gold;

step (5), acid washing: and (4) boiling and washing the sponge gold obtained in the step (4) for 0.5-1 h by respectively adopting nitric acid with the mass concentration of 20-30% and hydrochloric acid with the mass concentration of 10-15%, fully washing the sponge gold to be neutral by using deionized water, and drying the sponge gold in vacuum to obtain high-purity gold.

2. The method for producing high-purity gold according to claim 1, characterized in that:

in the step (2), the pH value of the gold solution A is 3, the reaction temperature is 70 ℃, and the reaction time is 2 hours; the flocculant is a prepared polyacrylamide solution, and the stirring time is 0.5 h; the standing time is 12 h.

3. The method for producing high purity gold according to claim 2, characterized in that:

in the step (3), the ion exchange resin pretreatment process is to place the cation resin in an exchange column, soak the cation resin in deionized water for 20 hours to make the cation resin in a swelling state, and then soak the cation resin in 5% of high-grade pure hydrochloric acid for 15 hours.

4. The method for producing high-purity gold according to claim 3, characterized in that:

in the step (4), the Au concentration of the gold solution C is not lower than 10/L, and the pH value of the solution is kept to be 4 in the reaction process; the reducing agent is a superior pure hydrogen peroxide solution, Au and H₂O₂The molar ratio is 1:3, and the reduction temperature is 80 ℃.

5. The method for producing high-purity gold according to claim 4, characterized in that:

in the step (5), the sponge gold obtained in the step (4) is boiled and washed for 1h by using nitric acid with the mass concentration of 20% and hydrochloric acid with the mass concentration of 10%.

6. Use of high purity gold produced by the production method of high purity gold according to any one of claims 1 to 5, characterized in that:

the high-purity gold is used as a film material of an integrated circuit and a semiconductor device.