阅读说明：本技术 一种水热氨浸从电镀污泥中选择性回收铜的方法 (Method for selectively recovering copper from electroplating sludge through hydrothermal ammonia leaching ) 是由 林璋 刘学明 冯震 吴榛 于 2021-01-09 设计创作，主要内容包括：本发明公开了一种水热氨浸从电镀污泥中选择性回收铜的方法,包括以下步骤：将电镀污泥烘干、粉碎；电镀污泥的水热氨浸,将电镀污泥、氨性浸出剂按一定固液比放入水热反应釜中,于预设温度下反应一段时间,反应后离心,过滤,水洗,得到含铜浸出液；沉淀法回收铜,调节含铜浸出液的pH,离心、过滤,水洗,回收铜,而氨性液添加一定量氨性浸出剂后回用于水热氨浸过程。本发明采用氨性浸出,选择性的分离了电镀污泥中的铜和铁,克服了传统酸浸回收工艺缺乏选择性的缺点。而且利用浸出剂的闭路循环系统,既节省了药剂,又减少了氨氮废水的排放。同时,与传统氨浸方法相比,水热提升了铜的浸出率,降低了铁的浸出率,强化了选择性分离的效果。(The invention discloses a method for selectively recovering copper from electroplating sludge by hydrothermal ammonia leaching, which comprises the following steps: drying and crushing the electroplating sludge; carrying out hydrothermal ammonia leaching on the electroplating sludge, putting the electroplating sludge and an ammonia leaching agent into a hydrothermal reaction kettle according to a certain solid-to-liquid ratio, reacting for a period of time at a preset temperature, centrifuging after reaction, filtering, and washing with water to obtain a copper-containing leaching solution; recovering copper by a precipitation method, adjusting the pH value of the copper-containing leaching solution, centrifuging, filtering, washing with water, and recovering copper, wherein a certain amount of ammoniacal leaching agent is added into the ammoniacal solution and then the ammoniacal solution is reused in the hydrothermal ammonia leaching process. The invention adopts ammoniacal leaching to selectively separate copper and iron in the electroplating sludge, and overcomes the defect of lack of selectivity of the traditional acid leaching recovery process. And a closed circulation system of the leaching agent is utilized, so that the agent is saved, and the discharge of ammonia nitrogen wastewater is reduced. Meanwhile, compared with the traditional ammonia leaching method, the leaching rate of copper is improved, the leaching rate of iron is reduced, and the selective separation effect is enhanced.)

1. A method for selective recovery of copper from electroplating sludge by hydrothermal ammonia leaching, the method comprising the steps of:

s1, drying and crushing the electroplating sludge;

s2, carrying out hydrothermal ammonia leaching on the electroplating sludge, putting the electroplating sludge and an ammonia leaching agent into a hydrothermal reaction kettle according to a certain solid-to-liquid ratio, reacting for a period of time at a preset temperature, centrifuging after reaction, filtering, and washing with water to obtain a copper-containing leaching solution;

s3, recovering copper by a precipitation method, adjusting the pH value of the copper-containing leachate, centrifuging, filtering, washing with water, and recovering copper.

2. The method for selective recovery of copper from electroplating sludge by hydrothermal ammonia leaching according to claim 1, wherein the components in the ammoniacal leaching agent comprise ammonia water, ammonium salt and water, the concentration of the total ammonia is 8mol/L to 12mol/L, and the concentration ratio of ammonia to ammonium salt is 2: 1-3: 1.

3. the method for selective recovery of copper from electroplating sludge in hydrothermal ammonia leaching according to claim 1, wherein the solid-to-liquid ratio of electroplating sludge to ammonia leaching agent is 1: 3-1: 5.

4. the method for selective recovery of copper from electroplating sludge by hydrothermal ammonia leaching according to claim 1, wherein the predetermined temperature is 160-200 ℃.

5. The method for selective recovery of copper from electroplating sludge by hydrothermal ammonia leaching according to claim 1, wherein the electroplating sludge and the ammonia leaching agent in step S2 are reacted in the hydrothermal reaction kettle for 2-4 h.

6. The method for selective recovery of copper from electroplating sludge according to claim 1, wherein the pH value of the copper-containing leachate is adjusted to 3-6 in step S3.

7. The method for selective recovery of copper from electroplating sludge by hydrothermal ammonia leaching according to claim 1, wherein the conditioning agent in step S3 is 1mol/L hydrochloric acid.

8. The method for selective recovery of copper from electroplating sludge according to claim 1, wherein the ammoniacal liquor obtained after copper recovery by precipitation in step S3 is reused in the hydrothermal ammonia leaching process after adding a certain amount of ammoniacal leaching agent.

9. The method for selective recovery of copper from electroplating sludge by hydrothermal ammonia leaching according to claim 8, wherein the amount of the ammonia leaching agent added is 1/4-3/4 times of the primary amount.

10. The method for selective recovery of copper from electroplating sludge by hydrothermal ammonia leaching according to claim 2, wherein the ammonium salt is one of ammonium sulfate and ammonium chloride.

Technical Field

The invention relates to the technical field of environmental protection, in particular to a method for selectively recovering copper from electroplating sludge by hydrothermal ammonia leaching.

Background

With the development of metal processing industry, the demand of electroplating treatment on metal parts in China is increasing. Electroplating sludge is solid hazardous waste generated in the production process of the electroplating industry, and 7 types of hazardous waste such as HW17, HW20-23, HW26, HW31 and the like in national records of hazardous waste in China all belong to electroplating sludge. The yield of the electroplating sludge is huge, and about 1000 million tons of electroplating sludge are generated in China every year. The main components of the electroplating are various electroplating waste liquid and sludge produced by an electrolytic bath solution through a chemical precipitation method, and the components of the produced electroplating sludge are different according to different production processes and waste liquid treatment methods adopted by different electroplating enterprises, so that the components of the electroplating sludge are very complex. The electroplating sludge often contains heavy metals such as zinc, nickel, copper, chromium and the like, which are generally difficult to biodegrade, easy to accumulate in organisms and show larger toxicity at lower concentration. If the electroplating sludge is not properly treated, serious water and soil heavy metal pollution can be caused, and the health of human beings is endangered. In addition, the grade of valuable metals such as zinc, nickel, copper, chromium, iron and the like contained in the electroplating sludge is far higher than that of rich ores, the potential value is very high, and considerable economic benefit and social benefit can be generated if the valuable metals are recycled. Therefore, the extraction of metals such as copper from electroplating sludge is very essential for environmental protection and sustainable development.

At present, the acid leaching method is generally adopted in industry to extract heavy metals from solid wastes, and the method has the advantages of high leaching efficiency, simple and convenient process, maturity and the like. The acid leaching process still has many problems. For example, the selectivity is poor, and a large amount of impurity ions such as Ca, Mg, Fe and the like enter a solution along with valuable metals in the acid leaching process to influence the subsequent utilization; the consumption of reagents such as acid and alkali is large, the electroplating sludge is usually alkalescent, and a large amount of acid is consumed in the acid leaching process; the metal recovery rate is low, the impurity content of the pickle liquor is high, valuable metals are seriously carried in the impurity removal process, and a large amount of metals are lost. The ammonia leaching method is based on the fact that in the leaching process, valuable metals such as Cu, Zn, Ni and the like are combined with free ammonia to form complex ions which enter a solution, and impurity ions such as Fe, Cr, Ca and the like are left in slag, so that the valuable metals and the impurity metals are separated, and the ammonia leaching method has good selectivity. But the method has the defects that ammonia nitrogen wastewater needs to be treated, the leaching efficiency of valuable metals is not high, a small amount of impurity metals are leached, and the like.

China patent 'copper-containing electroplating sludge pressurized hydrogen reduction' (CN 101928098A) dries, grinds and sieves electroplating sludge, then ammonia leaching is carried out at room temperature by taking ammonia water and ammonium sulfate solids as leaching agents, then pH is adjusted, a leaching solution is transferred to a high-pressure reaction kettle, hydrogen is introduced, the reaction is carried out for 50-90 minutes at the temperature of 130-160 ℃, filtration and separation are carried out after the reaction is finished, washing and drying are carried out, and Cu2O powder is obtained, wherein the copper leaching rate reaches 80%, and the leaching solution recovery rate reaches 96%. The method has mild reaction conditions and low cost, but the copper leaching rate is not high, the hydrogen is dangerous, and the process is complicated. Chinese patent 'a method for realizing nickel recovery from electroplating sludge' (CN 102399991A) carries out mixed acid leaching on the electroplating sludge, then adjusts pH, adds a composite extractant to realize the separation of nickel and coexisting heavy metals and the enrichment of nickel, then adds sulfuric acid into a nickel-containing extract to carry out back extraction to recover the nickel, and realizes the recycling of the composite extractant. The method uses an organic extractant, is easy to cause pollution, and the quality of the recovered nickel is not high. Chinese patent 'a method for comprehensively recovering valuable metals from electroplating sludge' (CN 104928478A) carries out ammonia leaching on the electroplating sludge to leach copper and nickel in the electroplating sludge, then uses sodium sulfide to recover the copper, and uses sodium hydroxide to precipitate and recover the nickel. Then sulfuric acid is used for leaching chromium in the electroplating sludge, and sodium carbonate is used for precipitating and recovering the chromium. The method has the advantages of low cost, no secondary pollution, long flow, more medicament addition and low leaching efficiency. Chinese patent "a method for recovering copper and nickel from electroplating sludge" (CN 107760872A) is characterized by that the electroplating sludge is ammonia-leached at a certain temp., then the leached liquid copper and nickel are separated by solvent extraction method. The method has low leaching rate, uses organic solvent, and has high cost, pollution and low metal product quality.

Disclosure of Invention

The invention aims to provide a method for selectively recovering copper from electroplating sludge by hydrothermal ammonia leaching, aiming at the defects of insufficient selectivity, low leaching efficiency and the like of the existing valuable metal recovery method in the electroplating sludge. According to the method, through hydrothermal ammonia leaching, valuable metal Cu in electroplating sludge is combined with free ammonia to form complex ions which enter a solution, and impurity ions such as Fe and Ca are left in slag, so that valuable metal and impurity metal are separated. And subsequently, the pH of the copper leaching solution is adjusted to precipitate copper in the form of hydroxide for recycling. The ammonia liquid is reused for the ammonia leaching process of the electroplating sludge to form a closed circulation system of the leaching agent, thereby saving the medicament and reducing the discharge of ammonia nitrogen wastewater.

The purpose of the invention can be achieved by adopting the following technical scheme:

a method for selective recovery of copper from electroplating sludge by hydrothermal ammonia leaching, the method comprising the steps of:

s1, drying and crushing the electroplating sludge;

s2, carrying out hydrothermal ammonia leaching on the electroplating sludge, putting the electroplating sludge and an ammonia leaching agent into a hydrothermal reaction kettle according to a certain solid-to-liquid ratio, reacting for a period of time at a preset temperature, centrifuging after reaction, filtering, and washing with water to obtain a copper-containing leaching solution;

s3, recovering copper by a precipitation method, adjusting the pH value of the copper-containing leachate, centrifuging, filtering, washing with water, and recovering copper.

Further, the components in the ammoniacal leaching agent comprise ammonia water, ammonium salt and water, the concentration of total ammonia is 8-12 mol/L, and the concentration ratio of ammonia to ammonium salt is 2: 1-3: 1.

further, the solid-to-liquid ratio of the electroplating sludge to the ammoniacal leaching agent is 1: 3-1: 5.

further, the preset temperature is 160-200 ℃.

Further, in the step S2, the reaction time of the electroplating sludge and the ammoniacal leaching agent in the hydrothermal reaction kettle is 2 to 4 hours.

Further, in the step S3, the pH of the copper-containing leachate is adjusted to 3-6.

Further, the regulator in step S3 is 1mol/L hydrochloric acid.

Further, in the step S3, a certain amount of ammoniacal leaching agent is added to the ammoniacal liquor obtained after the copper is recovered by the precipitation method, and the ammoniacal liquor is reused in the hydrothermal ammonia leaching process.

Furthermore, the addition amount of the ammoniacal leaching agent is 1/4-3/4 times of the initial use amount.

Further, the ammonium salt is one of ammonium sulfate and ammonium chloride.

Compared with the prior art, the invention has the following advantages and effects:

according to the invention, copper in electroplating sludge is recovered by hydrothermal ammonia leaching, valuable metal copper and free ammonia are combined to form complex ions to enter the solution, and impurity ions such as Fe and Ca are left in slag, so that valuable metal and impurity metal are separated. The pH value of the leachate is subsequently adjusted, copper is precipitated and recovered, the selective separation of copper is realized, the ammonia leachate is reused in the hydrothermal ammonia leaching process, a closed circulation system of the ammonia leaching agent is formed, the reagent is saved, and the discharge of ammonia nitrogen wastewater is reduced. Meanwhile, compared with the traditional ammonia leaching method, the method has the advantages that the leaching rate of copper is improved, the leaching rate of iron is reduced, and the selective separation effect is enhanced.

Drawings

FIG. 1 is a schematic flow diagram of a process for selective recovery of copper from electroplating sludge by hydrothermal ammonia leaching as disclosed in an example of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

The embodiment discloses a hydrothermal ammonia leaching method for selectively recovering copper in electroplating sludge, and a specific flow diagram is shown in figure 1. The method comprises the following specific steps:

s1, taking 2g of electroplating sludge generated by a certain factory, drying and crushing;

s1, carrying out hydrothermal ammonia leaching on the electroplating sludge, wherein the concentration of the crushed electroplating sludge, ammonia water, ammonium sulfate and water as main components and total nitrogen is 8mol/L, and the concentration ratio of ammonia to ammonium salt is 2: 1, namely an ammoniacal leaching agent, wherein the solid-liquid ratio is 1: 5, placing the mixture into a hydrothermal reaction kettle, reacting for 4 hours at 160 ℃, centrifuging after reaction, filtering, and washing with water to obtain copper-containing leachate;

s3, recovering copper by a precipitation method, adjusting the pH value of the copper-containing leachate to 5, centrifuging, filtering, washing with water, and recovering copper, wherein the ammoniacal liquor is added with an ammoniacal leaching agent with the primary dosage of 1/2 and then is reused in the hydrothermal ammonia leaching process.

Example 2

The embodiment discloses a hydrothermal ammonia leaching method for selectively recovering copper in electroplating sludge, and a specific flow diagram is shown in figure 1. The method comprises the following specific steps:

s1, taking 2g of electroplating sludge generated by a certain factory, drying and crushing;

s2, carrying out hydrothermal ammonia leaching on the electroplating sludge, wherein the concentration of the crushed electroplating sludge, ammonia water, ammonium sulfate and water as main components and total nitrogen is 8mol/L, and the concentration ratio of ammonia to ammonium salt is 2: 1, namely an ammoniacal leaching agent, wherein the solid-liquid ratio is 1: 5, placing the mixture into a hydrothermal reaction kettle, reacting for 4 hours at 180 ℃, centrifuging after reaction, filtering, and washing with water to obtain copper-containing leachate;

s3, recovering copper by a precipitation method, adjusting the pH value of the copper-containing leachate to 5, centrifuging, filtering, washing with water, and recovering copper, wherein the ammoniacal liquor is added with an ammoniacal leaching agent with the primary dosage of 1/2 and then is reused in the hydrothermal ammonia leaching process.

Example 3

The embodiment discloses a hydrothermal ammonia leaching method for selectively recovering copper in electroplating sludge, and a specific flow diagram is shown in figure 1. The method comprises the following specific steps:

s1, taking 2g of electroplating sludge generated by a certain factory, drying and crushing;

s2, carrying out hydrothermal ammonia leaching on the electroplating sludge, wherein the concentration of the crushed electroplating sludge, ammonia water, ammonium sulfate and water as main components and total nitrogen is 8mol/L, and the concentration ratio of ammonia to ammonium salt is 2: 1, namely an ammoniacal leaching agent, wherein the solid-liquid ratio is 1: 5, placing the copper-containing leaching solution into a hydrothermal reaction kettle, reacting for 4 hours at the temperature of 200 ℃, centrifuging after reaction, filtering and washing to obtain the copper-containing leaching solution;

s3, recovering copper by a precipitation method, adjusting the pH value of the copper-containing leachate to 5, centrifuging, filtering, washing with water, and recovering copper, wherein the ammoniacal liquor is added with an ammoniacal leaching agent with the primary dosage of 1/2 and then is reused in the hydrothermal ammonia leaching process.

TABLE 1 comparison of copper recovery parameters

As can be seen from Table 1, the initial copper recovery rate is 90.2% to 93.6%, the copper recovery rate after two times of recycling is 89.4% to 92.3%, the initial iron leaching rate is 0.15% to 0.39%, and the iron leaching rate after two times of recycling is 0.18% to 0.35%.

In conclusion, the selective recovery of valuable metals from the hydrothermal ammonia leaching electroplating sludge of the embodiment can be applied to electroplating sludge containing one or more metals such as chromium, nickel, copper, iron, zinc and the like, and solves the technical problems of insufficient selectivity, low leaching efficiency, complex process, incapability of thorough non-toxic treatment and the like of the existing electroplating sludge separation and recovery method.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.