Synthesis process for improving uniformity of basic copper chloride particles

Abstract

The invention relates to a synthesis process for improving the particle uniformity of basic copper chloride, which comprises the following steps: firstly, adding sodium citrate, EDTA-2Na or a compound solution of the sodium citrate and the EDTA-2Na into an acidic etching solution as a crystallization regulating agent to form a reversible complex with Cu < 2 + >; then, adding the pretreated acidic liquid and alkaline liquid into a reactor in a constant proportion at the same time at a constant speed in a parallel flow manner, and carrying out a precipitation reaction at a temperature interval of 60-80 DEG C and a pH value interval of 4.0-4.8; according to the method, the concentration of free copper ions is buffered through the regulating agent, explosive nucleation is inhibited, and a reaction system is kept stable in combination with parallel flow feeding, so that a uniform and controllable crystallization process is guided. The obtained copper chloride hydroxide product has the excellent characteristics of narrow particle size distribution, regular morphology, high tap density and good fluidity, and the product quality and application performance are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of industrial solid waste resource utilization technology, and in particular to a synthesis process for improving the uniformity of basic copper chloride particles. Background Technology

[0002] Basic copper chloride, as an important functional copper compound, is widely used in feed additives, wood preservatives, pigments, and catalysts. With the increasing emphasis on resource recycling, the acidic etching wastewater (rich in Cu) generated in the PCB industry is also gaining traction. 2 + Cl - ) and alkaline etching waste liquid (rich in NH3, OH) - The process of synthesizing basic copper chloride from raw materials through neutralization and precipitation has become a mainstream technical route that combines environmental protection and economic benefits. Its core reaction is: 2Cu 2+ + Cl - + 3OH - → Cu2(OH)3Cl↓.

[0003] However, this process faces a common and challenging technical bottleneck in actual industrial production: poor particle uniformity of the resulting product. Specifically, this manifests as: (1) a wide particle size distribution, ranging from several micrometers to hundreds of micrometers; (2) irregular particle morphology, such as a mixture of flaky, needle-like, and blocky particles; and (3) severe particle agglomeration. This non-uniformity directly leads to low tap density, poor flowability, and difficulty in dispersion in application systems, seriously affecting its mixing uniformity in feed, its coverage performance in coatings, and the exposure of active sites in catalytic reactions, thus restricting the high-value application of the product.

[0004] Various attempts have been made in the industry to address this problem, mainly focusing on optimizing macroscopic process parameters, such as precisely controlling the pH value at the reaction endpoint, increasing the reaction temperature, strengthening stirring to improve mixing, and increasing aging time to promote crystal growth. In addition, some studies have added various dispersants or surfactants in the later stages of the reaction or post-treatment to reduce agglomeration. However, these methods are mostly stopgap measures, primarily inhibiting secondary agglomeration of already formed particles or providing limited intervention in the later stages of crystal growth, but failing to fundamentally regulate the nucleation and growth kinetics in the early stages of crystallization.

[0005] Crystallography principles indicate that the final uniformity of particles is determined by the competitive relationship between the nucleation and growth stages. In traditional processes, high-concentration reactants are rapidly mixed, instantly generating extremely high supersaturation in localized areas, leading to "explosive" heterogeneous nucleation. After a large number of nuclei are generated instantaneously, the reactant concentration drops sharply, transitioning to a stage dominated by crystal growth. This inevitably results in crystals that nucleate earlier growing larger and those that nucleate later growing smaller, ultimately forming a wide particle size distribution. Simultaneously, uncontrolled free growth can lead to crystals preferentially growing along different crystal planes, resulting in irregular morphologies.

[0006] Therefore, developing a novel process that can intervene at the molecular level to effectively regulate the release and binding behavior of copper ions in the precipitation reaction, thereby guiding uniform and controllable crystallization, is of great significance for improving the quality of basic copper chloride products and promoting the upgrading of etching waste liquid resource utilization technology. This invention proposes a synthesis process to improve the uniformity of basic copper chloride particles, in order to solve the above-mentioned problems. Summary of the Invention

[0007] The purpose of this invention is to overcome the above-mentioned shortcomings and provide a synthesis process that improves the uniformity of basic copper chloride particles, thereby solving the inherent defects of existing processes for producing basic copper chloride from etching waste liquid, such as wide particle size distribution, irregular morphology, and poor uniformity.

[0008] The objective of this invention is achieved as follows: A synthesis process for improving the uniformity of basic copper chloride particles, using acidic etching waste liquid and alkaline etching waste liquid as raw materials, includes the following: S1. Pretreatment with crystallization regulator: Add crystallization regulator to acidic etching waste liquid, dissolve and mix evenly at 40-70℃ with stirring to obtain pretreated acidic liquid; the crystallization regulator is sodium citrate, disodium ethylenediaminetetraacetate or a mixture of the two. S2. Controlled co-current precipitation reaction: The pretreated acidic solution obtained in step S1 and the alkaline etching waste liquid are simultaneously and uniformly added to the reactor at a constant volume flow rate ratio through an independent metering and conveying system for reaction; the reaction conditions are controlled as follows: temperature 60-80℃, pH value at the reaction endpoint 4.0-4.8, and total feeding time 1.5-4 hours. S3. Post-processing: After the reaction is completed, the slurry is aged at a temperature range of 60-80℃ for 30-90 minutes, and then undergoes solid-liquid separation, washing, and drying to obtain basic copper chloride product.

[0009] Further, in step S1, when the crystallization regulator is sodium citrate, its addition amount is 5%-20% of the total copper moles in the acid etching waste liquid; when the crystallization regulator is disodium ethylenediaminetetraacetate, its addition amount is 0.5%-3% of the total copper moles.

[0010] Further, in step S1, the crystallization regulator is a mixture of sodium citrate and disodium ethylenediaminetetraacetate, wherein the amount of sodium citrate added is 5%-15% of the total molar amount of copper, and the amount of disodium ethylenediaminetetraacetate added is 0.1%-1% of the total molar amount of copper.

[0011] Further, in step S2, the volume flow ratio of the pretreatment acidic liquid to the alkaline etching waste liquid is 1:(1.05-1.25).

[0012] Furthermore, in step S2, an online pH meter is used to monitor the pH value of the reaction slurry in real time, and the instantaneous feeding speed of the two materials is finely adjusted through feedback control to stabilize the final pH in the range of 4.0-4.8.

[0013] Furthermore, in step S3, the washing is performed using pure water or deionized water in a multi-stage countercurrent washing process until the conductivity of the washing liquid is lower than 1000 μS / cm.

[0014] Furthermore, in step S3, the drying temperature is below 100°C.

[0015] A basic copper chloride product prepared by the above-mentioned synthesis process for improving the uniformity of basic copper chloride particles, wherein the particle size distribution span of the product satisfies: (D90 - D10) / D50 ≤ 1.0, where D10, D50, and D90 are the particle sizes corresponding to a cumulative volume distribution percentage of 10%, 50%, and 90% as measured by laser particle size analysis.

[0016] Furthermore, the product has a tap density ≥1.70 g / mL and an angle of repose ≤35°.

[0017] Furthermore, the particle morphology of the product is a regular short rod shape or a spherical shape.

[0018] Compared with the prior art, the beneficial effects of the present invention are: This invention provides a synthesis process for improving the uniformity of basic copper chloride particles. Before the precipitation reaction occurs, one or more crystallization regulators are introduced into the acidic etching solution. These regulators can react with Cu... 2+ Reversible coordination occurs, forming a moderately stable complex, effectively reducing the free Cu in the solution. 2+ The instantaneous concentration is controlled to suppress the supersaturation peak at the beginning of the reaction, transforming uncontrollable explosive nucleation into controllable homogeneous nucleation. Based on this, through complementary reaction engineering enhancement methods, an ideal macroscopic environment for homogeneous crystallization is created. It possesses the following advantages: (1) The uniformity of the product is greatly improved: the crystallization path is fundamentally changed by the “slow release” effect of the crystallization regulator; the particle size distribution range ((D90-D10) / D50) of the obtained basic copper chloride product can be stably controlled below 1.0, the D50 particle size can be adjusted in the range of 10-30μm according to the process conditions, and the particle morphology is highly consistent, mostly regular short rods or spherical shapes, which is significantly better than the traditional process.

[0019] (2) Strong process controllability and high reproducibility: The type and amount of crystallization regulator, the rate of co-current feeding, reaction pH, temperature and other key parameters can be precisely quantified and controlled, which makes the production process highly repeatable and stable, which is conducive to large-scale and standardized production.

[0020] (3) Combining compatibility and economy: The selected sodium citrate and EDTA-2Na are compatible with common components in etching waste liquid, such as chlorates, ammonium salts, and organic additives, and do not cause harmful side reactions; sodium citrate is inexpensive and readily available, and although EDTA-2Na has a higher unit price, the amount used is very small, so the overall cost increase is limited and the economic benefits are significant.

[0021] (4) Improve the overall performance of the product: The improvement of particle uniformity directly brings benefits such as increased tap density, reduced angle of repose, enhanced flowability, and more controllable specific surface area, which greatly improves its performance in end applications.

[0022] (5) Green and environmentally friendly: This method improves product quality without introducing new environmental pollution factors, and is an optimization and upgrade of existing green resource utilization processes. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the method flow of the present invention. Detailed Implementation

[0024] To better understand the technical solution of the present invention, a detailed description will be provided below in conjunction with relevant illustrations. It should be understood that the specific embodiments described below are not intended to limit the specific implementation of the technical solution of the present invention, but are merely possible implementations of the technical solution of the present invention. It should be noted that the descriptions of the positional relationships of the components herein, such as component A being located above component B, are based on the relative positions of the components in the illustrations and are not intended to limit the actual positional relationships of the components.

[0025] See Figure 1 , Figure 1 A schematic diagram of the method flow of the present invention has been drawn. The present invention relates to a synthesis process for improving the uniformity of basic copper chloride particles, which is carried out through the following steps: S1, Pretreatment stage with crystallization regulator: The measured crystallization regulator is added to the acidic etching waste liquid, and fully dissolved and mixed under continuous stirring and a certain temperature, preferably in the range of 40-70℃, to form a pretreatment solution. The crystallization regulator is selected from those that can react with Cu. 2+ The preferred substances for forming soluble complexes are sodium citrate (C6H5Na3O7) or disodium ethylenediaminetetraacetate (EDTA-2Na, C6H5Na3O7). 10 H 14 (N2Na2O8) or a mixture of both.

[0026] Dosage of regulator: When sodium citrate is used alone, its addition amount is 5%-20% of the total molar amount of copper in the acidic etching waste liquid; when EDTA-2Na is used alone, its addition amount is 0.5%-3% of the total molar amount of copper; when the two are used in combination, the addition amount of sodium citrate is 5%-15% of the total molar amount of copper, and the addition amount of EDTA-2Na is 0.1%-1% of the total molar amount of copper. This dosage range has been verified by a large number of experiments and can achieve the best balance between economic cost and control effect.

[0027] S2, Controlled precipitation reaction stage: The pretreated acidic etching solution and alkaline etching waste solution are fed simultaneously and at a constant and matched flow ratio through two independent metering and conveying systems. The metering and conveying systems can be metering pumps. The mixture is injected at a constant and uniform speed into a reaction vessel with high-efficiency stirring and jacket temperature control. The stirring paddle of the reaction vessel is preferably a combined axial and radial flow stirring paddle. It should be noted that the "pouring method" or "semi-batch method" of adding one solution to another solution at once or rapidly is absolutely prohibited.

[0028] S2.1 Feeding speed control: The total feeding time should be controlled between 1.5 and 4 hours, depending on the size of the reactor and the amount of material fed. The goal is to maintain a low and stable supersaturation state inside the reactor.

[0029] S2.2, Precise control of reaction conditions: S2.21. Temperature: The reaction temperature is precisely controlled within the range of 60-80℃ through the jacketed circulating medium, with temperature fluctuation not exceeding ±2℃.

[0030] S2.22, pH value: The pH value of the reaction slurry is monitored in real time using an online pH meter. By fine-tuning the instantaneous flow rate ratio of the two feed streams, the pH value is stabilized within the optimal range of 4.0-4.8 throughout the entire reaction process, especially at the reaction endpoint, while maintaining a constant total volume ratio. This pH range is most conducive to the formation of the basic copper chloride single phase and can effectively inhibit the generation of other basic copper salts or copper hydroxide impurities.

[0031] S2.23. Stirring intensity: Maintain a sufficient and uniform stirring speed to ensure rapid mixing of reactants at the microscale and eliminate areas of excessively high local concentrations.

[0032] S3, Crystal ripening and post-processing stage: S3.1 After the feeding is completed, continue to maintain the reaction system at 60-80°C and age it at a moderate stirring speed for 30-90 minutes. This process allows small crystals to dissolve and large crystals to continue growing, i.e., Oswald ripening, which further homogenizes the particle size.

[0033] S3.2 After aging, the slurry undergoes solid-liquid separation. Solid-liquid separation can be performed using a vacuum belt filter. Deionized water or pure water is used for multi-stage countercurrent washing to remove ammonium salts (NH4Cl) and residual soluble impurities until the conductivity of the washing liquid meets the standard.

[0034] S3.3 The washed filter cake is dried at a low temperature of less than 100°C. Drying can be done by disc drying or fluidized bed drying to prevent the particles from sintering and agglomerating due to high temperature. The final product is a basic copper chloride powder with good flowability and uniform color.

[0035] The following are specific implementation examples: Example 1

[0036] In this embodiment 1, a synthesis process for improving the uniformity of basic copper chloride particles is described, using sodium citrate as a crystallization regulator. Acidic etching waste liquid (Liquid A): Taken from the PCB production line, analysis showed Cu content... 2+ The concentration was 1.48 mol / L (approximately 94 g / L), and the total acidity was 4.8 mol / L. Alkaline etching waste liquid (Liquid B): Taken from the PCB production line, analysis showed a copper concentration of 105 g / L, with [Cu(NH3)4] as the solvent. 2+ It exists in the form of ammonia nitrogen, with a concentration of approximately 9.8%.

[0037] The specific steps are as follows: 1. Pretreatment: Measure 500 L of solution A into a pretreatment tank and heat it to 55°C; while stirring, slowly add 8.9 kg of sodium citrate, which is equivalent to 12% of the total copper molars in solution A; Continue stirring for 40 minutes to ensure complete dissolution, resulting in a clear pretreated solution A.

[0038] 2. Co-current reaction: Turn on the stirring and jacket heating system of the 5000 L glass-lined reactor, and add 200 L of deionized water as the base liquid; set the reaction temperature to 70±1℃; Two high-precision metering pumps are used to simultaneously and uniformly pump pretreatment solution A and solution B into the reactor at a volume flow ratio of A:B = 1:1.18; the total feeding time is controlled within 3 hours. Throughout the feeding process, the pH of the reaction slurry was precisely stabilized at 4.3 by monitoring with an online pH meter and fine-tuning the pump speed through an automatic control system.

[0039] 3. Aging: After the material is added, maintain the temperature at 70℃ and continue stirring for aging for 60 minutes.

[0040] 4. Post-processing: The aged slurry is pumped into a 40㎡ fully automatic belt vacuum filter and washed with 60℃ pure water in a four-stage countercurrent process until the conductivity of the final washing liquid is less than 800μS / cm; the resulting wet filter cake with a water content of about 30% is sent to a disc dryer and dried with hot air at 85℃ until the moisture content is less than 2.5%; The dried product was sieved through an 80-mesh vibrating screen to obtain approximately 92 kg (dry basis) of blue-green basic copper chloride powder. Example 2

[0041] This Example 2 presents a synthesis process for improving the uniformity of basic copper chloride particles, using a combination of sodium citrate and EDTA-2Na as a crystallization regulator. The raw materials are the same as in Example 1. The specific steps are as follows: 1. Pretreatment: Measure 500 L of solution A into a pretreatment tank and heat it to 60℃. While stirring, first add 7.4 kg of sodium citrate, which is equivalent to 10% of the total copper moles. After it is completely dissolved, add 0.37 kg of EDTA-2Na, which is equivalent to 0.5% of the total copper moles. Continue stirring for 50 minutes until it is completely dissolved.

[0042] 2. Co-current reaction: The reactor temperature is set at 72±1℃. Pretreatment solution A and solution B are pumped in co-currently at a volume flow ratio of A:B = 1:1.20, and the total feeding time is extended to 3.5 hours to achieve milder reaction conditions; through precise control, the final pH of the reaction is stabilized at 4.5.

[0043] 3. Aging: Aging at 72℃ for 75 minutes.

[0044] 4. Post-processing: Same as in Example 1; approximately 91.5 kg of basic copper chloride powder was finally obtained.

[0045] The resulting product also exhibits excellent storage stability.

[0046] Comparative Example 1 (Traditional process, no regulators, rapid mixing): 1. Take equal amounts of solution A and solution B as in Example 1, without adding any crystallization regulator; 2. First, add all 500 L of solution A into the reactor at once, then start stirring and heating to 70°C; 3. Then, within 30 minutes, quickly pump all of solution B into the reactor; 4. The final pH of the reaction is approximately 4.3. Due to rapid mixing, the pH fluctuates greatly. 5. Then age at 70℃ for 60 minutes; 6. The post-processing steps are the same as in Example 1.

[0047] Comparative Example 2 (with added regulator, but using sequential feeding, not concurrent flow): Take an equal amount of solution A as in Example 1, and pretreat it by adding sodium citrate according to the same method and dosage as in Example 1; add all the pretreated solution A to the reactor and heat it to 70°C; then pump all the solution B in at a uniform rate over 2.5 hours. This is a semi-batch method, not a co-current method; the final pH is controlled at 4.3; aging and post-treatment are the same as in Example 1.

[0048] Comparative Example 3 (co-current feeding, but insufficient amount of regulator): The operating procedure of Comparative Example 3 is exactly the same as that of Example 1, the only difference being that the amount of sodium citrate added is only 2% of the total number of copper moles.

[0049] Comparative Example 4 (optimized process parameters of temperature, pH, and stirring, but without the addition of regulators): Comparative Example 4 attempts to simulate the fine control of the present invention, but without adding a regulator; using the same co-flow feeding method as Example 1, pretreatment liquid A and liquid B are pumped in co-flow at a volume flow ratio of A:B = 1:1.18, with a feeding time of 3 hours, and the temperature is strictly controlled at 70±1℃, with an endpoint pH of 4.3; aging and post-treatment are the same.

[0050] The physicochemical properties of the products obtained in the above embodiments and comparative examples were systematically characterized, and the key data are summarized in the table below:

[0051] Results analysis: 1. Comparison of core parameters: Particle size distribution span is the most critical indicator for measuring particle uniformity. The span values ​​of Examples 1 and 2 are both less than 1.0, showing excellent monodispersity; while the comparative examples are all greater than 1.6, indicating a wide distribution. This directly demonstrates the superior effect of this invention in improving uniformity.

[0052] 2. The core role of the regulator: Comparing Example 1 and Comparative Example 4, it is evident that, under the same refined process operation, the addition of a crystallization regulator (Example 1) is the decisive factor in obtaining a narrow distribution. Comparative Example 4 only optimizes macroscopic parameters and cannot overcome the fundamental problem of explosive nucleation.

[0053] 3. Importance of Feeding Method: Comparing Example 1 and Comparative Example 2, it is evident that even with the addition of sufficient regulator, the product uniformity (span 2.09) of the non-co-current sequential feeding (Comparative Example 2) is significantly worse than that of the co-current feeding (Example 1, span 0.96). "Co-current feeding" is a crucial engineering technique for ensuring the reaction system remains in a low-supersaturation stable state, complementing the role of the regulator.

[0054] 4. Effect of the dosage of the regulator: The effect of Comparative Example 3 (2% sodium citrate) is between that of the traditional process and the present invention, indicating that there is an effective threshold concentration. Only when a certain amount is reached (such as 5% or more as described in the present invention) can the "slow-release" regulating effect be fully exerted.

[0055] 5. Improved overall performance: Uniform particles result in higher tap density and better flowability, which is extremely beneficial for product packaging, transportation and downstream applications.

[0056] In summary, this invention, through the innovative combination of "pre-complexation of crystallization regulator" and "precise reaction with dual-flow parallel flow," successfully achieves multi-scale precise control of the basic copper chloride crystallization process from molecular to macroscopic levels, solving the long-standing problem of product uniformity. The technical effect is significant and it has outstanding industrial application value.

[0057] This invention provides a synthesis process for improving the uniformity of basic copper chloride particles. Before the precipitation reaction occurs, one or more crystallization regulators are introduced into a copper ion source (acidic etching solution). These regulators can react with Cu... 2+ Reversible coordination occurs, forming a moderately stable complex. This process does not prevent the final formation of basic copper chloride, but rather acts as a "buffer" or "slow-release agent," effectively reducing the amount of free Cu in the solution. 2+ The instantaneous concentration is controlled to suppress the supersaturation peak at the beginning of the reaction, transforming uncontrollable explosive nucleation into controllable homogeneous nucleation. Based on this, a suitable macroscopic environment for homogeneous crystallization is created through complementary reaction engineering enhancement techniques.

[0058] The above are merely specific application examples of the present invention and do not constitute any limitation on the scope of protection of the present invention. All technical solutions formed by equivalent transformations or substitutions fall within the scope of protection of the present invention.

Claims

1. A synthesis process for improving the uniformity of basic copper chloride particles, using acidic etching waste liquid and alkaline etching waste liquid as raw materials, characterized in that, Includes the following: S1. Pretreatment with crystallization regulator: Add crystallization regulator to acidic etching waste liquid, dissolve and mix evenly at 40-70℃ with stirring to obtain pretreated acidic liquid; The crystallization regulator is sodium citrate, disodium ethylenediaminetetraacetate, or a mixture of both. S2. Controlled co-current precipitation reaction: The pretreated acidic solution obtained in step S1 and the alkaline etching waste liquid are simultaneously and uniformly added to the reactor at a constant volume flow rate ratio through an independent metering and conveying system for reaction; the reaction conditions are controlled as follows: temperature 60-80℃, pH value at the reaction endpoint 4.0-4.8, and total feeding time 1.5-4 hours. S3. Post-processing: After the reaction is completed, the slurry is aged at a temperature range of 60-80℃ for 30-90 minutes, and then undergoes solid-liquid separation, washing, and drying to obtain basic copper chloride product.

2. The synthesis process for improving the uniformity of basic copper chloride particles according to claim 1, characterized in that: In step S1, when the crystallization regulator is sodium citrate, its addition amount is 5%-20% of the total copper moles in the acid etching waste liquid; when the crystallization regulator is disodium ethylenediaminetetraacetate, its addition amount is 0.5%-3% of the total copper moles.

3. The synthesis process for improving the uniformity of basic copper chloride particles according to claim 1, characterized in that: In step S1, the crystallization regulator is a mixture of sodium citrate and disodium ethylenediaminetetraacetate, wherein the amount of sodium citrate added is 5%-15% of the total molar amount of copper, and the amount of disodium ethylenediaminetetraacetate added is 0.1%-1% of the total molar amount of copper.

4. The synthesis process for improving the uniformity of basic copper chloride particles according to claim 1, characterized in that: In step S2, the volume flow ratio of the pretreatment acidic solution to the alkaline etching waste solution is 1:(1.05-1.25).

5. The synthesis process for improving the uniformity of basic copper chloride particles according to claim 1, characterized in that: In step S2, an online pH meter is used to monitor the pH value of the reaction slurry in real time, and the instantaneous feeding speed of the two materials is finely adjusted through feedback control to stabilize the final pH in the range of 4.0-4.

8.

6. The synthesis process for improving the uniformity of basic copper chloride particles according to claim 1, characterized in that: In step S3, the washing is performed using pure water or deionized water in a multi-stage countercurrent washing process until the conductivity of the washing liquid is lower than 1000 μS / cm.

7. The synthesis process for improving the uniformity of basic copper chloride particles according to claim 1, characterized in that: In step S3, the drying temperature is below 100°C.

8. A basic copper chloride product prepared by the synthesis process for improving the uniformity of basic copper chloride particles according to any one of claims 1-7, characterized in that: The particle size distribution span of the product satisfies: (D90 - D10) / D50≤ 1.0, where D10, D50, and D90 are the particle sizes corresponding to the cumulative volume distribution percentages measured by laser particle size analysis reaching 10%, 50%, and 90%, respectively.

9. The basic copper chloride product prepared by the synthesis process for improving the uniformity of basic copper chloride particles according to claim 8, characterized in that: The product has a tap density ≥1.70 g / mL and an angle of repose ≤35°.

10. The basic copper chloride product prepared by the synthesis process for improving the uniformity of basic copper chloride particles according to claim 8 or 9, characterized in that: The product has a regular short rod-shaped or spherical particle morphology.

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