CN105819595A - Method for recycling gold in situ from gold-containing wastewater - Google Patents

Abstract

The invention discloses a method for recycling gold in situ from gold-containing wastewater. The method is free of pollution, simple in process and convenient and rapid to implement, and intermediate consumables can be reutilized. The technological method of resin adsorption, gold-loaded resin desorption, diaphragm electrodeposition and barren resin gold adsorption is adopted, so that the process has the advantages of being high in production efficiency, low in production cost, free of wastewater transfer cost, thorough in gold recycling and the like; enrichment, elution desorption and electrolysis are carried out in situ, gold recycling is achieved, and the risk of wastewater transfer is avoided. According to the method, chelate resin is adopted to adsorb gold, an acidic thiourea system is adopted to carry out elution desorption on gold-loaded resin, barren resin obtained after desorption is returned to adsorb gold, gold in a pregnant solution obtained after desorption is extracted with a diaphragm electrodeposition method, a barren solution obtained after electrolysis is returned and used for desorbing the gold-loaded resin, and thus the technological process with the gold adsorption resin and the desorption solution reused is formed. When the method is applied to wastewater containing minor gold or trace gold, gold can be thoroughly recycled, and the gold residual in the barren solution can be reduced to 0.001 ppm and is almost zero.

Description

Method for recovering gold in situ from gold-bearing wastewater

technical field

The invention relates to a method for recovering gold from gold-containing wastewater, in particular to a method for recovering gold in situ by adopting a process of resin adsorption-gold-loaded resin desorption-diaphragm electrowinning.

Background technique

In recent years, the electronic information technology industry has developed rapidly, and the speed of upgrading electronic products is getting faster and faster. At the same time, with the improvement of people's living standards, the strong demand for gold-plated parts has led to a sharp increase in the amount of electronic waste and gold-plated parts waste. If the contained rare and precious metals are not recovered, it will not only cause serious pollution to the environment, but also cause a great waste of resources. The development of the above-mentioned industries will produce a large amount of gold-containing waste water, such as: waste plating solution produced during electroplating of circuit boards or gold-plated parts, washing water for washing plated parts and equipment, and various gold-containing waste water produced in other places where gold is used. waste water. Usually, the content of gold in these gold-containing wastewater is low, even trace amounts. On the one hand, their recovery is technically difficult, and on the other hand, it is often not cost-effective economically. Therefore, there is an urgent need for a process that not only meets environmental protection requirements, but also realizes in-situ recovery of gold.

At present, the more common enrichment and recovery technologies from gold-bearing wastewater mainly include: zinc replacement method, activated carbon/resin adsorption, ion exchange, electrodeposition method, etc., among which:

Zinc replacement method, the quality of zinc directly affects the consumption of zinc and the taste of gold mud, this method is rarely used;

Activated carbon and resin adsorption methods can recover gold more completely, but the existing technology is to extract gold by incinerating activated carbon or resin adsorbed with gold, which will cause serious secondary pollution;

Electrodeposition method is a research hotspot in recent years. It has high gold extraction efficiency and high purity gold recovery, but the ordinary electrolysis process is prone to concentration polarization.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for recovering gold in situ from gold-containing wastewater, which is pollution-free, simple in process, convenient and fast, and intermediate consumables can be reused.

In order to solve the problems of the technologies described above, the technical solution adopted in the present invention is:

The method for recovering gold in situ from gold-containing wastewater of the present invention includes washing and swelling the gold-absorbing resin, and it also includes the following steps:

1) directly pumping the gold-containing wastewater generated on-site into an ion-exchange column placed on-site and filled with the gold-absorbing resin, wherein the gold-absorbing resin absorbs gold in the gold-containing wastewater to form a gold-loaded resin;

2) Before eluting and desorbing the gold-loaded resin, wash the gold-loaded resin with pure water until the solution discharged from the ion-exchange column is in a clear state;

3) For elution of the gold-loaded resin, add the eluent of the acidic thiourea system to the ion exchange column until the gold-loaded resin is completely immersed in it and no bubbles are generated. The gold-loaded resin is eluted and desorbed, and after 1hr-3hr of eluted and desorbed, an enriched precious solution containing Au(SCH ₂ H ₄ ) ²⁺ complex cations and a gold-absorbing resin after degolding are generated, wherein the gold-absorbing resin is recovered and then use;

4) Place the enriched precious liquid in the cathode chamber of the electrolytic cell used in the diaphragm electrowinning process, place a sulfuric acid solution in the anode chamber of the electrolytic cell, use an ion exchange membrane to carry out the diaphragm electrowinning process, and undergo electrolysis The reaction generates gold with a certain purity and a barren solution containing acidic thiourea solution in a complex form, wherein the barren solution is recovered and reused.

When washing the gold-loaded resin with pure water, the gold-absorbing resin used is an anionic resin.

The eluent is thiourea sulfate solution or thiourea hydrochloride solution, wherein the concentration of thiourea is 30g/L～150g/L, the concentration of sulfuric acid is 15g/L～120g/L, and the concentration of hydrochloric acid is 5g/L～30g/L , the elution and desorption flow rate is 60ml/min to 400ml/min, the elution and desorption temperature is 20°C to 60°C, and the eluent cycle is 10min to 90min.

The ion-exchange membrane used for electrowinning of the diaphragm is an anion-exchange membrane resistant to strong acidity.

The concentration of the sulfuric acid solution in the diaphragm electrodeposition anode chamber is 15g/L-120g/L, and the circulation flow rate is 1L/h-5L/h.

The electrowinning current density of the separator is 15A/m ² -100A/m ² .

The method for recovering gold in situ from gold-containing wastewater of the present invention adopts the process of resin adsorption + gold-loaded resin desorption + diaphragm electrodeposition + poor resin gold absorption, so that the process of recovering gold in situ from gold-containing wastewater has high production efficiency and production efficiency. Low cost, no waste water transfer costs, complete gold recovery, etc., the most important thing is that it can be enriched in situ ("in situ" means that the waste water is directly recovered at the place where the waste water is generated, on the one hand, gold extraction in situ can avoid On the other hand, the risks generated during the transfer of wastewater refer to obtaining elemental gold in situ, which is easy to operate; "enrichment" refers to the concentration of wastewater), elution, desorption, and electrolysis, so as to realize the resource utilization of gold and avoid the transfer of wastewater risks of.

The method is to absorb gold by using chelating resin, and use an acidic thiourea system to elute and desorb the gold-loaded resin. The final barren solution is returned and used to desorb the gold-loaded resin to form a process flow in which the gold-absorbed resin and the desorbed liquid are recycled, which has the characteristics of high benefit, low production cost and high purity of gold recovery.

When the present invention is applicable to waste water containing trace amounts of gold, the gold therein can be completely recovered, and the residual gold in the barren solution can be reduced to 0.001ppm, which is almost zero.

Description of drawings

Fig. 1 is the process flow block diagram of the method of the present invention.

detailed description

As shown in Figure 1, the process of the present invention is as follows:

Step 1. Preparation

Utilize the gold-containing waste water tank to collect the gold-containing waste water for use.

Step 2. Resin absorbs gold

Weigh a certain amount of resin (also known as gold-absorbing resin, anionic resin is used in the present invention) and place it in an ion exchange column, wash the resin with deionized water, swell after soaking for a period of time after washing, and then place the resin containing The gold wastewater is pumped into the ion exchange column and fully fused with the resin, and the swollen resin absorbs the gold in the gold-containing wastewater to form a gold-loaded resin. According to the concentration of gold in the gold-containing wastewater, the number of stages and the speed of the ion exchange column are set to ensure that the gold content in the wastewater after the ion exchange column has been adsorbed by gold is reduced to below 0.001ppm (reaching the level of direct discharge) Standard), to achieve complete recovery of gold.

Step 3, washing the gold-loaded resin

Before the above-mentioned gold-loaded resin is eluted and desorbed, the gold-loaded resin is washed with pure water until the viscosity of the effluent in the ion-exchange column is almost the same as that of pure water (that is, the washing process is until the ion-exchange column It can also be said that the solution discharged from the ion exchange column is in a clear state.

Step 4, eluting the gold-loaded resin

Add the eluent of the acidic thiourea system to the ion exchange column, and add the eluent until the gold-loaded resin can be completely immersed in it and no air bubbles are generated. The elution and desorption (that is, the gold on the gold-loaded resin is completely desorbed), the elution and desorption time is 1-3 hours, after that, the enriched precious solution containing Au(SCH ₂ H ₄ ) ²⁺ complex cations is generated and the gold-absorbing resin after degolding, wherein the gold-absorbing resin is recycled and reused.

Described eluent selects thiourea sulfate solution for use, wherein thiourea concentration is 30g/L～150g/L (preferred 60g/L), sulfuric acid concentration is 15g/L～120g/L (preferred 45g/L), hydrochloric acid concentration is 5g/L～30g/L, the elution and desorption flow rate is 60ml/min～400ml/min (preferably 200mL/h), the elution and desorption temperature is 20℃～60℃ (preferably room temperature), and the eluent circulation period is 10min ~90min.

Step 5. Gold withdrawal by diaphragm electrodeposition

Transfer the enriched precious liquid to the cathode chamber in the electrolytic cell, and place a sulfuric acid solution with a weight ratio of 15g/L to 120g/L and a weight of 500mL in the anode chamber of the electrolytic cell, and use an ion exchange membrane to carry out In the electrolysis of the diaphragm electrowinning process, since the two pole solutions are strongly acidic solutions, the ion exchange membrane must use an anion exchange membrane resistant to strong acid. After the electrolysis reaction, a certain purity of gold and a poor solution containing only acidic thiourea solution in a complex form are generated, wherein the purity of gold can reach more than 99.5%, and the poor solution can be recycled and reused.

The anode of described electrolyzer is made of titanium material, and cathode adopts stainless steel plate, and electrode size is 6cm * 4.5cm, and the distance between electrodes is 2cm～5cm (preferably 2cm), and eluent (being sulfuric acid solution) flow velocity is 1L/ h ~ 5L/h (preferably 2L/h), the current density is 15A/m ² ~ 100A/m ² (preferably 18.5A/m ² ).

Step 6. The desorbed resin is used again to adsorb gold-containing waste water for recycling.

Step 7, continue to treat the barren solution produced in the above step 5 with the thiourea system until the solution no longer contains gold.

Step 8, collecting the electrolyzed gold.

Claims (6)

1. from containing gold waste water situ reclaim gold a method, including to inhale gold resin wash, swelling, it is characterised in that: also comprise the steps:

1) waste water containing gold produced at scene is pumped directly into the scene of being positioned over and is contained with in the described ion exchange column inhaling gold resin, wherein, inhales gold resin absorption and forms gold loaded resin containing after the gold in gold waste water；

2) before to described gold loaded resin eluting desorbing, with pure water, this gold loaded resin is washed, until the solution discharged by described ion exchange column is clear state；

3) to gold loaded resin eluting, the eluent of acid thiourea system is added until being totally submerged wherein by gold loaded resin and bubble-free generation in described ion exchange column, afterwards, employing circulates mode and described gold loaded resin carries out under air-tight state eluting desorbing, generates containing Au (SCH after eluting desorbing 1hr-3hr₂H₄)²⁺Suction gold resin after your liquid of enrichment of complex cation and Tuo Jin, wherein, inhales gold resin recycling；

4) expensive for described enrichment liquid is placed in the cathode chamber in the electrolysis bath used used by diaphragm electrodeposition technique, sulfuric acid solution is held in the anode chamber of this electrolysis bath, ion exchange membrane is used to carry out diaphragm electrodeposition technique, generate the gold of certain purity through cell reaction and contain the lean solution that acid thiourea solution is complex pattern, wherein, lean solution recycling.

Method the most according to claim 1, it is characterised in that: when washing described gold loaded resin with pure water, suction gold resin used is anionic resin.

Method the most according to claim 1, it is characterized in that: described eluent is Sulfuric Thiourea solution or hydrochloric acid thiourea solution, wherein thiourea concentration is 30g/L～150g/L, sulfuric acid concentration is 15g/L～120g/L, concentration of hydrochloric acid is 5g/L～30g/L, eluting desorbing flow velocity is 60ml/min～400ml/min, and eluting desorption temperature is 20 DEG C～60 DEG C, and eluent cycle period is 10min～90min.

Method the most according to claim 1, it is characterised in that: the ion exchange membrane of described diaphragm electrodeposition is resistance to highly acid anion exchange membrane.

Method the most according to claim 1, it is characterised in that: the concentration of described diaphragm electrodeposition anode chamber sulfuric acid solution is 15g/L～120g/L, and rate of circulating flow is 1L/h～5L/h.

Method the most according to claim 1, it is characterised in that: described diaphragm electrodeposition electric current density is 15A/m²～100A/m²。