A zero-increment online recovery method for alkaline etching waste liquid

Abstract

The invention discloses a zero-increment online recovery method for alkaline etching waste liquid, which belongs to the technical field of circuit board alkaline etching waste liquid treatment. The method of the invention realizes zero increment of alkaline etching waste liquid, fully recovers copper resources and ammonia nitrogen resources, and the recovered product has high added value and obvious economic benefits. The present invention adopts a multi-stage fully enclosed absorption of ammonia by a combined process of low-temperature evaporation and ammonia absorption tower to ensure that ammonia is fully reused without raw material loss. The evaporation temperature of the present invention is 50-60°C, which can be completely obtained by using waste heat inside the factory. It is a low-grade heat source, which can realize the cascade utilization of energy relative to ordinary steam evaporation, and achieves the purpose of energy saving. The present invention realizes zero generation of hazardous waste of alkaline etching waste liquid, avoids the environmental risks of hazardous waste transportation process, and has obvious environmental benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit board alkaline etching waste liquid treatment, and in particular to a zero-increment online recovery method for alkaline etching waste liquid. Background Art

[0002] In the production process of printed circuit boards, etching liquid is needed to etch the required circuit patterns on the copper foil board. Depending on the etching process, the etching liquid is divided into acidic and alkaline. In the alkaline etching process, as the amount of copper etched increases, the ammonia and ammonium chloride content of the etching liquid decreases accordingly, resulting in a slower etching speed. In order to ensure the etching quality, it is necessary to reduce the copper content in the etching liquid, and add ammonia, ammonium chloride and etching additives to restore and maintain the etching ability. However, the added ammonia and ammonium chloride will cause the etching liquid to expand. This part of the expanded etching liquid cannot be reused and can only be outsourced for disposal as hazardous waste. On the one hand, there is a risk of hazardous waste polluting the environment. On the other hand, due to outsourcing, copper resources cannot realize their due value. Summary of the invention

[0003] The embodiment of the present invention provides a zero-increment online recovery method for alkaline etching waste liquid. The method combines the mature direct electrolysis or extraction electrolysis process on the market, develops a new process, and performs source resource utilization on the expanded etching waste liquid. In the process of copper extraction and reuse of the etching liquid, the waste liquid does not expand, and the copper resources and ammonia nitrogen resources are fully recovered. The waste water and waste gas are treated and discharged in compliance with the standards, and no waste residue is generated in the resource utilization process. The contents of the present invention are as follows:

[0004] The object of the present invention is to provide a zero-increment online recovery method for alkaline etching waste liquid, the technical point of which is that it comprises the following steps:

[0005] Step 1, performing a first evaporation concentration on the alkaline etching waste liquid to 30-50% of the original liquid volume to obtain concentrated alkaline etching waste liquid;

[0006] Step 2, absorbing the ammonia obtained in the evaporation and concentration process in step 1 with hydrochloric acid in an absorption tower to generate an absorption liquid, wherein the pH value of the absorption liquid is 3-6;

[0007] Step 3, monitoring the concentration of chloride ions in the absorption liquid and the specific gravity of the absorption liquid in step 2, and when the concentration of chloride ions in the absorption liquid reaches 100-160 g / L and the specific gravity of the absorption liquid reaches a preset threshold, performing a second concentration and evaporation on the absorption liquid to 35-60% of the original liquid volume to obtain an ammonium chloride concentrate;

[0008] Step 4, the ammonium chloride concentrated solution obtained in step 3 is used again to prepare an alkaline etching sub-liquid for reuse in the etching production line;

[0009] Step 5: The alkaline etching waste liquid concentrated in step 1 is directly fed into the extraction electrolysis copper extraction system for recycling.

[0010] In order to better implement the above method, the time for the first evaporation and concentration in step 1 of the zero-increment online recovery method of alkaline etching waste liquid of the present invention is 5-8 hours.

[0011] In order to better implement the above method, the temperature of the first evaporation and concentration in step 1 of the zero-increment online recovery method of alkaline etching waste liquid of the present invention is 50-60°C.

[0012] In order to better implement the above method, in step 1 of the zero-increment online recovery method of alkaline etching waste liquid of the present invention, the copper content in the alkaline etching waste liquid is 120-140 g / L, and the ammonia content is 10-15 wt%.

[0013] In order to better implement the above method, the concentration of hydrochloric acid in step 2 of the zero-increment online recovery method of alkaline etching waste liquid of the present invention is 30-32wt%.

[0014] In order to better implement the above method, the preset threshold value of the specific gravity of the absorption liquid in step 3 of the zero-increment online recovery method of alkaline etching waste liquid of the present invention is 1.0500-1.0700.

[0015] Compared with the prior art, the zero-increment online recovery method of alkaline etching waste liquid of the present invention has the following beneficial effects:

[0016] 1. The zero-increment online recovery method of alkaline etching waste liquid of the present invention realizes zero increment of alkaline etching waste liquid, fully recovers copper resources and ammonia nitrogen resources, and the recovered products have high added value and obvious economic benefits.

[0017] 2. The present invention adopts a combination process of low-temperature evaporation and ammonia absorption tower to adopt multi-stage fully enclosed absorption of ammonia, ensuring that the ammonia is fully recycled without raw material loss. The evaporation temperature of the present invention is 50-60°C, which can be completely obtained by using the waste heat inside the factory. It is a low-grade heat source. Compared with ordinary steam evaporation, it can realize the cascade utilization of energy and achieve the purpose of energy saving.

[0018] 3. The present invention achieves zero generation of hazardous wastes of alkaline etching waste liquid, avoids environmental risks in the process of transporting hazardous wastes, and has obvious environmental benefits. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0020] The copper recovery process currently used by a certain PCB enterprise is to extract copper for reuse by electrolysis. This process produces 50 tons of alkaline etching waste liquid per month, which can only be sold at a low price. The copper content in the alkaline etching waste liquid is 120-140g / L, and the ammonia content is 10-15wt%. The copper resources and ammonia resources are seriously lost. After the zero-increment online recovery method of alkaline etching waste liquid of the present invention is used, the alkaline etching waste liquid can be completely treated by the present invention, the copper is completely recovered by electrolysis, and the ammonia nitrogen resources are made into ammonium chloride for reuse, with obvious economic benefits.

[0021] Example 1

[0022] A zero-increment online recovery method for alkaline etching waste liquid comprises the following steps:

[0023] Step 1, the alkaline etching waste liquid is evaporated and concentrated for the first time to 40% of the original liquid volume to obtain concentrated alkaline etching waste liquid. As a preferred embodiment of the present invention, the temperature of the first evaporation and concentration is 55° C., and the time of the first evaporation and concentration is 6.5 h;

[0024] Step 2, absorbing the ammonia obtained in the evaporation and concentration process in step 1 with hydrochloric acid in an absorption tower to generate an absorption liquid, wherein the pH value of the absorption liquid is 4.5, and preferably, the concentration of the hydrochloric acid in this embodiment is 31wt%;

[0025] Step 3, monitoring the concentration of chloride ions in the absorption liquid and the specific gravity of the absorption liquid in step 2, when the concentration of chloride ions in the absorption liquid reaches 130 g / L and the specific gravity of the absorption liquid reaches a preset threshold value of 1.0600, concentrating and evaporating the absorption liquid for a second time to 47.5% of the original liquid volume to obtain an ammonium chloride concentrated solution;

[0026] Step 4, the ammonium chloride concentrated solution obtained in step 3 is used again to prepare an alkaline etching sub-liquid for reuse in the etching production line;

[0027] Step 5: The alkaline etching waste liquid concentrated in step 1 is directly fed into the extraction electrolysis copper extraction system for recycling.

[0028] Example 2

[0029] A zero-increment online recovery method for alkaline etching waste liquid comprises the following steps:

[0030] Step 1, the alkaline etching waste liquid is evaporated and concentrated for the first time to 30% of the original liquid volume to obtain concentrated alkaline etching waste liquid. As a preferred embodiment of the present invention, the temperature of the first evaporation and concentration is 50° C., and the time of the first evaporation and concentration is 5 hours;

[0031] Step 2, absorbing the ammonia obtained in the evaporation and concentration process in step 1 with hydrochloric acid in an absorption tower to generate an absorption liquid, wherein the pH value of the absorption liquid is 3. Preferably, the concentration of the hydrochloric acid in this embodiment is 30wt%;

[0032] Step 3, monitoring the concentration of chloride ions in the absorption liquid and the specific gravity of the absorption liquid in step 2, when the concentration of chloride ions in the absorption liquid reaches 100 g / L and the specific gravity of the absorption liquid reaches a preset threshold value of 1.0500, concentrating and evaporating the absorption liquid for a second time to 35% of the original liquid volume to obtain an ammonium chloride concentrated solution;

[0033] Step 4, the ammonium chloride concentrated solution obtained in step 3 is used again to prepare an alkaline etching sub-liquid for reuse in the etching production line;

[0034] Step 5: The alkaline etching waste liquid concentrated in step 1 is directly fed into the extraction electrolysis copper extraction system for recycling.

[0035] Example 3

[0036] A zero-increment online recovery method for alkaline etching waste liquid comprises the following steps:

[0037] Step 1, the alkaline etching waste liquid is evaporated and concentrated for the first time to 50% of the original liquid volume to obtain concentrated alkaline etching waste liquid. As a preferred embodiment of the present invention, the temperature of the first evaporation and concentration is 60° C., and the time of the first evaporation and concentration is 8 hours;

[0038] Step 2, absorbing the ammonia obtained in the evaporation and concentration process in step 1 with hydrochloric acid in an absorption tower to generate an absorption liquid, wherein the pH value of the absorption liquid is 6. Preferably, the concentration of the hydrochloric acid in this embodiment is 32wt%;

[0039] Step 3, monitoring the concentration of chloride ions in the absorption liquid and the specific gravity of the absorption liquid in step 2, when the concentration of chloride ions in the absorption liquid reaches 160 g / L and the specific gravity of the absorption liquid reaches a preset threshold value of 1.0700, concentrating and evaporating the absorption liquid for a second time to 60% of the original liquid volume to obtain an ammonium chloride concentrated solution;

[0040] Step 4, the ammonium chloride concentrated solution obtained in step 3 is used again to prepare an alkaline etching sub-liquid for reuse in the etching production line;

[0041] Step 5: The alkaline etching waste liquid concentrated in step 1 is directly fed into the extraction electrolysis copper extraction system for recycling.

[0042] Example 4

[0043] A zero-increment online recovery method for alkaline etching waste liquid comprises the following steps:

[0044] Step 1, the alkaline etching waste liquid is evaporated and concentrated for the first time to 35% of the original liquid volume to obtain concentrated alkaline etching waste liquid. As a preferred embodiment of the present invention, the temperature of the first evaporation and concentration is 52° C., and the time of the first evaporation and concentration is 6 hours;

[0045] Step 2, absorbing the ammonia obtained in the evaporation and concentration process in step 1 with hydrochloric acid in an absorption tower to generate an absorption liquid, wherein the pH value of the absorption liquid is 4. Preferably, the concentration of the hydrochloric acid in this embodiment is 30.5wt%;

[0046] Step 3, monitoring the concentration of chloride ions in the absorption liquid and the specific gravity of the absorption liquid in step 2, when the concentration of chloride ions in the absorption liquid reaches 110 g / L and the specific gravity of the absorption liquid reaches a preset threshold value of 1.0550, concentrating and evaporating the absorption liquid for a second time to 40% of the original liquid volume to obtain an ammonium chloride concentrated solution;

[0047] Step 4, the ammonium chloride concentrated solution obtained in step 3 is used again to prepare an alkaline etching sub-liquid for reuse in the etching production line;

[0048] Step 5: The alkaline etching waste liquid concentrated in step 1 is directly fed into the extraction electrolysis copper extraction system for recycling.

[0049] Example 5

[0050] A zero-increment online recovery method for alkaline etching waste liquid comprises the following steps:

[0051] Step 1, the alkaline etching waste liquid is evaporated and concentrated for the first time to 45% of the original liquid volume to obtain concentrated alkaline etching waste liquid. As a preferred embodiment of the present invention, the temperature of the first evaporation and concentration is 57° C., and the time of the first evaporation and concentration is 7 hours;

[0052] Step 2, absorbing the ammonia obtained in the evaporation and concentration process in step 1 with hydrochloric acid in an absorption tower to generate an absorption liquid, wherein the pH value of the absorption liquid is 5. Preferably, the concentration of the hydrochloric acid in this embodiment is 31.5wt%;

[0053] Step 3, monitoring the concentration of chloride ions in the absorption liquid and the specific gravity of the absorption liquid in step 2, and when the concentration of chloride ions in the absorption liquid reaches 150 g / L and the specific gravity of the absorption liquid reaches a preset threshold value of 1.0650, the absorption liquid is concentrated and evaporated for a second time to 50% of the original liquid volume to obtain an ammonium chloride concentrated solution;

[0054] Step 4, the ammonium chloride concentrated solution obtained in step 3 is used again to prepare an alkaline etching sub-liquid for reuse in the etching production line;

[0055] Step 5: The alkaline etching waste liquid concentrated in step 1 is directly fed into the extraction electrolysis copper extraction system for recycling.

[0056] In summary, based on the process of the present invention, zero-increment online recovery and treatment of alkaline waste liquid can be carried out, so that ammonia resources can be converted into ammonium chloride for recycling, and the copper sold at a low price in the waste liquid can all be made into electrolytic copper for high-price recovery. The process is simple and easy to control, and the economic benefits are obvious.

[0057] The above description is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A zero-increment online recovery method for alkaline etching waste liquid, characterized in that: The following steps are involved: Step 1, performing a first evaporation concentration on the alkaline etching waste liquid to 30-50% of the original liquid volume to obtain concentrated alkaline etching waste liquid; Step 2, absorbing the ammonia obtained in the evaporation and concentration process in step 1 with hydrochloric acid in an absorption tower to generate an absorption liquid, wherein the pH value of the absorption liquid is 3-6; Step 3, monitoring the concentration of chloride ions in the absorption liquid and the specific gravity of the absorption liquid in step 2, and when the concentration of chloride ions in the absorption liquid reaches 100-160 g / L and the specific gravity of the absorption liquid reaches a preset threshold, performing a second concentration and evaporation on the absorption liquid to 35-60% of the original liquid volume to obtain an ammonium chloride concentrate; Step 4, the ammonium chloride concentrated solution obtained in step 3 is used again to prepare an alkaline etching sub-liquid for reuse in the etching production line; Step 5, directly feeding the concentrated alkaline etching waste liquid in step 1 into the extraction electrolysis copper extraction system for recycling; The time for the first evaporation and concentration in step 1 is 5-8 hours; The temperature of the first evaporation and concentration in step 1 is 50-60°C; The preset threshold value of the specific gravity of the absorption liquid in step 3 is 1.0500-1.0700.

2. A zero-increment online recovery method for alkaline etching waste liquid according to claim 1, characterized in that: The concentration of hydrochloric acid in step 2 is 30-32 wt %.