Method for the neutralization of lime plant dust slurry in hydrometallurgy and use thereof

Abstract

The application belongs to the technical field of resource utilization, and particularly relates to a method for using lime plant dedusting ash slurry for neutralization in hydrometallurgy and application thereof. The method for using lime plant dedusting ash slurry for neutralization in hydrometallurgy comprises the following steps: S1, performing digestion treatment on the dedusting ash collected by the lime plant; S2, preparing dedusting ash slurry; S3, adding the prepared dedusting ash slurry into acidic ore slurry or tailings generated in the hydrometallurgy process, adjusting the pH of the ore slurry, and separating the ore slurry into solid and liquid to complete the neutralization of the acidic ore slurry or tailings. The dedusting ash of the lime plant is used as raw material, and the dedusting ash is treated through a specific method. The prepared dedusting ash slurry is used for the neutralization of the acidic ore slurry and tailings generated in the hydrometallurgy process. The method can achieve good neutralization effect, and the reaction is mild and smooth, which can reduce the risk of local high pH. The use of the dedusting ash can realize the resource utilization of the dedusting ash of the lime plant, and has good environmental protection benefits.

Description

Technical Field

[0001] This invention belongs to the field of resource utilization technology, specifically relating to a method for neutralizing lime plant dust removal slurry in wet metallurgy and its application. Background Technology

[0002] In the hydrometallurgical process of preparing nickel-cobalt hydroxide (MHP) from laterite nickel ore under high-pressure acid leaching, the leachate and tailings are usually in a strongly acidic state. It is necessary to adjust the pH of the system by adding an alkaline neutralizing agent to achieve the subsequent hydrolysis, precipitation, and separation of impurities such as iron and aluminum. Currently, lime slurry prepared from slaked quicklime is commonly used in industrial production as a neutralizing agent, which rapidly introduces OH- into the slurry system. - This increases the pH value of the slurry, thereby completing the neutralization and impurity removal process.

[0003] However, existing neutralization techniques based primarily on lime slurry have gradually revealed certain limitations during long-term industrial operation. ① The alkaline components in lime slurry dissolve and react rapidly, easily forming localized high-pH areas near the feeding point. This leads to uneven neutralization reactions, affecting the selective hydrolysis and precipitation of iron and aluminum impurities, and potentially causing the loss of valuable metals through encapsulation. ② The lime slurry neutralization reaction is quite vigorous, requiring strict control over the feeding rate, stirring conditions, and reaction time. When handling high-acidity slurries or under fluctuating operating conditions, the system's operational stability is insufficient. ③ Quicklime is obtained through high-temperature calcination of limestone, resulting in high energy consumption and carbon emissions during production. Furthermore, the large consumption in the hydrometallurgical neutralization process leads to persistently high production costs. On the other hand, during lime production, the baghouse dust collection system in lime plants generates a large amount of calcium-containing dust. This type of dust typically contains calcium oxide, calcium carbonate, and small amounts of inert minerals, exhibiting overall alkaline characteristics and possessing certain neutralization potential based on its chemical composition. However, due to its complex phase composition and the large differences in the reaction kinetics of its various alkaline components, it is mostly treated as a general solid waste and disposed of through stockpiling or landfill in the current technology. A mature and stable industrial utilization scheme has not yet been formed, which not only wastes resources but also increases environmental management and safety risks.

[0004] Therefore, there is an urgent need to develop a hydrometallurgical neutralization method that can fully utilize the multi-phase coexistence characteristics of lime plant dust, ensure the neutralization and impurity removal effects of hydrometallurgical processes, achieve a smooth and controllable neutralization reaction process, and take into account the resource utilization of industrial solid waste. Summary of the Invention

[0005] This invention aims to provide a method for neutralizing lime plant dust slurry in hydrometallurgical processes and its application. The invention uses lime plant dust as raw material and processes it using a specific method. The resulting dust slurry is used to neutralize acidic slurries and tailings generated during hydrometallurgical processes. This not only achieves a good neutralization effect but also ensures a gentle and gradual reaction during the neutralization process, reducing the risk of localized high pH levels and promoting the selective precipitation of iron and aluminum impurities. Furthermore, the use of lime plant dust enables resource utilization, reducing solid waste accumulation and environmental risks, resulting in significant environmental benefits. While meeting process requirements, it also significantly reduces the overall cost of neutralizing agents, achieving substantial economic benefits.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a method for neutralizing lime plant dust removal slurry in wet metallurgy, comprising the following steps: S1. The dust collected from the lime plant is digested and treated. S2. Prepare dust removal slurry; S3. Add the prepared dust removal slurry to the acidic slurry or tailings produced in the hydrometallurgical process to adjust the pH of the slurry. When the pH of the slurry rises to the set range, the iron, aluminum and other impurity ions in the slurry undergo hydrolysis and precipitation. After solid-liquid separation, the leachate after impurity removal or the tailings after neutralization are obtained.

[0007] As one embodiment of the method for neutralizing lime plant dust removal slurry in wet metallurgy according to the present invention, the collected dust removal ash contains components such as calcium oxide, calcium carbonate, and inert minerals.

[0008] The dust collected by this invention contains both calcium oxide and calcium carbonate. Calcium oxide reacts rapidly in the initial stage of digestion and neutralization, providing initial neutralization capacity, while calcium carbonate reacts slowly in the acidic system, forming a slow-release alkali source. This constitutes a multiphase alkali source synergistic neutralization system. At the same time, by using pre-digestion and controllable slurry conditioning, calcium oxide and calcium carbonate in the dust can form a synergistic reaction system, avoiding drastic local pH fluctuations caused by the instantaneous release of a single highly active alkali source. This makes the pH rise of the slurry more gradual and controllable, which is beneficial for the selective precipitation of iron and aluminum impurities in the subsequent process.

[0009] As one embodiment of the method for neutralizing lime plant dust removal slurry in wet metallurgy as described in this invention, the inert mineral components include feldspar minerals (such as potassium feldspar and sodium feldspar), mica minerals (such as muscovite and biotite), etc.

[0010] As one embodiment of the method for neutralizing lime plant dust removal slurry in wet metallurgy according to the present invention, the digestion treatment includes the following steps: pouring the collected dust removal ash into a digestion device and adding water for digestion treatment.

[0011] As one embodiment of the method for neutralizing lime plant dust removal slurry in wet metallurgy according to the present invention, the amount of water added is 5-30% of the total mass of dust removal ash in the digestion device.

[0012] This invention adds a specific proportion of water during the digestion and treatment of dust, which can ensure that the calcium oxide in the dust undergoes a full hydration reaction, while also effectively suppressing dust from flying.

[0013] As one embodiment of the method for neutralizing lime plant dust removal slurry in wet metallurgy according to the present invention, the preparation of dust removal slurry includes the following steps: adding water to the digested dust removal ash, stirring, and obtaining dust removal slurry.

[0014] As one embodiment of the method of using lime plant dust removal slurry for wet metallurgical neutralization according to the present invention, the mass ratio of the dust removal slurry to the added water is 1:(3~6).

[0015] As one embodiment of the method for neutralizing lime plant dust removal slurry in wet metallurgy according to the present invention, the stirring rate is 300~500 r / min and the stirring time is 1~6 h.

[0016] As one embodiment of the method for neutralizing lime plant dust removal slurry in wet metallurgy according to the present invention, the solid content of the dust removal slurry is 10~30%.

[0017] In this invention, by adjusting the solid content of the dust removal slurry to 10-30%, the water-cement ratio (3-6):1, and the reaction time to 1-6 h, the neutralization capacity and reaction rate can be controlled to meet the neutralization requirements of slurries and tailings with different acidity.

[0018] This invention achieves a stable and controllable neutralized slurry with a certain solid content by precisely controlling the amount of water used for preparing the dust removal slurry, the stirring frequency, and the preparation time, and balancing the dissolution efficiency of each component. This allows different alkaline components in the dust removal ash to form a uniform dispersion in the slurry system, weakening the influence of the difference in reaction rates of each component on the neutralization process, thereby obtaining a neutralized slurry with stable and controllable reaction behavior.

[0019] As one embodiment of the method of using lime plant dust removal slurry for hydrometallurgical neutralization according to the present invention, the neutralization effect of the dust removal slurry on acidic slurry or tailings generated in the hydrometallurgical process is 45-55% of that of lime milk.

[0020] The present invention also claims protection for the application of the method of using the lime plant dust removal slurry for neutralization in hydrometallurgical processes in adjusting the pH value of leachate and tailings during hydrometallurgical processes.

[0021] Compared with the prior art, the present invention has the following beneficial effects: (1) Compared with the single high-activity alkali source system of quicklime, the dust removal ash phase in this invention contains both calcium oxide and calcium carbonate. Through the multiphase alkali source synergistic neutralization mechanism, the neutralization reaction process can be slowed down, reducing the risk of local high pH in the reaction process, and is more conducive to the selective precipitation of iron and aluminum impurities.

[0022] (2) The dust removal slurry prepared by the present invention can replace 45-55% of the amount of lime milk under the same endpoint pH conditions, significantly reducing the consumption of quicklime. When the dust removal slurry prepared by the specific process of the present invention is applied to the wet metallurgical process, the removal rate of iron impurity ions in the slurry can reach up to 99.96%, and the removal rate of aluminum impurity ions can reach up to 95.86%.

[0023] (3) The dust removal slurry prepared by the present invention has good fluidity and is less prone to scaling than existing neutralizing agents (quicklime). The system has high operational stability and is suitable for continuous production conditions in hydrometallurgy.

[0024] (4) The method of the present invention can realize the resource utilization of dust from lime plants, reduce the accumulation of solid waste and environmental risks, and has good environmental benefits. At the same time, under the premise of meeting the process requirements, it can significantly reduce the overall cost of neutralizing agents. Using the dust removal slurry prepared by the present invention to neutralize high-pressure acidic slurry, the actual amount of quicklime and annual dust removal slurry production can be replaced by about 25,200 tons / year, and the annual benefit is calculated to be about RMB 6.124 million to RMB 8.152 million, which has significant economic benefits. Attached Figure Description

[0025] Figure 1 This is a comparison diagram of the neutralization effect of dust and lime in the experimental examples of this invention. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] Unless otherwise specified, the experimental and operational methods used in the examples and comparative examples are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0028] Example 1

[0029] A method for neutralizing lime plant dust removal slurry in wet metallurgy includes the following steps: S1. The dust generated during the lime calcination process is collected through the bag filter dust collection system of the lime plant. The collected dust is added to the digestion device and water is added at a ratio of 20% for digestion treatment, so that the calcium oxide in it can fully undergo the hydration reaction, while suppressing dust flying. The collected dust contains calcium oxide, calcium carbonate and a small amount of inert mineral components. S2. Preparation of dust removal slurry: In the digested slurry, by precisely controlling the amount of water used for slurry preparation, the stirring frequency, and the slurry preparation time, the dissolution efficiency between each component is balanced, so that different alkaline components in the dust removal ash form a uniform dispersion in the slurry system, weakening the influence of the difference in reaction rate of each component on the neutralization process, thereby obtaining a neutralized slurry with stable and controllable reaction behavior, and producing a dust removal slurry with a certain solid content. The mass ratio of dust collector ash to added water is 1:4, the stirring rate is 500 r / min, the stirring time is 4h, and the solid content of the dust collector ash slurry is 20%. S3. Add the prepared dust removal slurry to the acidic slurry or tailings produced in the hydrometallurgical process, adjust the pH of the slurry, and when the pH of the slurry rises to the set range, the iron, aluminum and other impurity ions in the slurry undergo hydrolysis and precipitation. After solid-liquid separation, the leachate after impurity removal or the tailings after neutralization are obtained, thus completing the neutralization of the acidic slurry or tailings.

[0030] Using the method in this embodiment of the invention, the removal rate of iron impurity ions in the slurry reached 99.95%, and the removal rate of aluminum impurity ions reached 95.43%.

[0031] Example 2

[0032] A method for neutralizing lime plant dust removal slurry in wet metallurgy includes the following steps: S1. The dust generated during the lime calcination process is collected through the bag filter dust collection system of the lime plant. The collected dust is added to a digestion device and water is added at a ratio of 5% for digestion treatment, so that the calcium oxide in it can fully undergo a hydration reaction, while suppressing dust flying. The collected dust contains calcium oxide, calcium carbonate and a small amount of inert mineral components. S2. Preparation of dust removal slurry: In the digested slurry, by precisely controlling the amount of water used for slurry preparation, the stirring frequency, and the slurry preparation time, the dissolution efficiency between each component is balanced, so that different alkaline components in the dust removal ash form a uniform dispersion in the slurry system, weakening the influence of the difference in reaction rate of each component on the neutralization process, thereby obtaining a neutralized slurry with stable and controllable reaction behavior, and producing a dust removal slurry with a certain solid content. The mass ratio of dust collector ash to added water is 1:2, the stirring rate is 500 r / min, the stirring time is 1 h, and the solid content of the dust collector ash slurry is 30%. S3. Add the prepared dust removal slurry to the acidic slurry or tailings produced in the hydrometallurgical process, adjust the pH of the slurry, and when the pH of the slurry rises to the set range, the iron, aluminum and other impurity ions in the slurry undergo hydrolysis and precipitation. After solid-liquid separation, the leachate after impurity removal or the tailings after neutralization are obtained, thus completing the neutralization of the acidic slurry or tailings.

[0033] Using the method in this embodiment of the invention, the removal rate of iron impurity ions in the slurry reached 99.96%, and the removal rate of aluminum impurity ions reached 95.01%.

[0034] Example 3

[0035] A method for neutralizing lime plant dust removal slurry in wet metallurgy includes the following steps: S1. The dust generated during the lime calcination process is collected through the bag filter dust collection system of the lime plant. The collected dust is added to a digestion device and water is added at a ratio of 30% for digestion treatment, so that the calcium oxide in it can fully undergo a hydration reaction, while suppressing dust from flying. The collected dust contains calcium oxide, calcium carbonate and a small amount of inert mineral components. S2. Preparation of dust removal slurry: In the digested slurry, by precisely controlling the amount of water used for slurry preparation, the stirring frequency, and the slurry preparation time, the dissolution efficiency between each component is balanced, so that different alkaline components in the dust removal ash form a uniform dispersion in the slurry system, weakening the influence of the difference in reaction rate of each component on the neutralization process, thereby obtaining a neutralized slurry with stable and controllable reaction behavior, and producing a dust removal slurry with a certain solid content. The mass ratio of dust collector ash to added water is 1:6, the stirring rate is 500 r / min, the stirring time is 6h, and the solid content of the dust collector ash slurry is 15%. S3. Add the prepared dust removal slurry to the acidic slurry or tailings produced in the hydrometallurgical process, adjust the pH of the slurry, and when the pH of the slurry rises to the set range, the iron, aluminum and other impurity ions in the slurry undergo hydrolysis and precipitation. After solid-liquid separation, the leachate after impurity removal or the tailings after neutralization are obtained, thus completing the neutralization of the acidic slurry or tailings.

[0036] Using the method in this embodiment of the invention, the removal rate of iron impurity ions in the slurry reached 99.87%, and the removal rate of aluminum impurity ions reached 95.86%.

[0037] Example 4

[0038] A method for neutralizing lime plant dust removal slurry in wet metallurgy includes the following steps: S1. The dust generated during the lime calcination process is collected through the bag filter dust collection system of the lime plant. The collected dust is added to the digestion device and water is added at a ratio of 20% for digestion treatment, so that the calcium oxide in it can fully undergo the hydration reaction, while suppressing dust flying. The collected dust contains calcium oxide, calcium carbonate and a small amount of inert mineral components. S2. Preparation of dust removal slurry: In the digested slurry, by precisely controlling the amount of water used for slurry preparation, the stirring frequency, and the slurry preparation time, the dissolution efficiency between each component is balanced, so that different alkaline components in the dust removal ash form a uniform dispersion in the slurry system, weakening the influence of the difference in reaction rate of each component on the neutralization process, thereby obtaining a neutralized slurry with stable and controllable reaction behavior, and producing a dust removal slurry with a certain solid content. The mass ratio of dust collector ash to water is 1:7, the stirring frequency is 500 r / min, the stirring time is 4h, and the solid content of the dust collector ash slurry is 10%. S3. Add the prepared dust removal slurry to the acidic slurry or tailings produced in the hydrometallurgical process, adjust the pH of the slurry, and when the pH of the slurry rises to the set range, the iron, aluminum and other impurity ions in the slurry undergo hydrolysis and precipitation. After solid-liquid separation, the leachate after impurity removal or the tailings after neutralization are obtained, thus completing the neutralization of the acidic slurry or tailings.

[0039] Compared with Example 1, the only difference in this example is that the mass ratio of dust removal ash to water is 1:7 during the preparation of the dust removal slurry.

[0040] Using the method in this embodiment of the invention, the removal rate of iron impurity ions in the slurry reached 97.56%, and the removal rate of aluminum impurity ions reached 92.21%.

[0041] Experiment Example 1: Comparison of the neutralization capacity of dust and lime slurry Experimental objective: To verify the neutralization capacity of lime plant dust removal slurry in a wet metallurgical acidic system, and to compare its neutralization effect with that of conventional lime slurry, thereby evaluating its equivalent substitution ratio.

[0042] I. Experimental Methods An acidic solution with the same acidity was selected as a simulated mineral slurry. Under the same experimental conditions, neutralization experiments were conducted using lime slurry and dust removal slurry of the same concentration. The stirring conditions, reaction temperature, and feeding method were kept consistent (neutralizing 150 ml of 10% dilute sulfuric acid solution). The endpoint pH=7 was used as the neutralization endpoint criterion, and the cumulative amount of different neutralizing agents added was recorded.

[0043] II. Experimental Results Experimental results are as follows Figure 1As shown. Under the same endpoint pH conditions, multiple sets of repeated experiments showed that the cumulative addition amount of the dust-removing slurry of the present invention required to achieve the same neutralization effect as lime slurry is approximately 1.8 to 2.2 times that of lime slurry, and its neutralization capacity per unit volume is approximately 44.47% of that of lime slurry of the same concentration. By increasing the solid content of the dust-removing slurry and extending the reaction contact time, its equivalent neutralization capacity can be increased to 45% to 55% of that of lime slurry.

[0044] The dust removal slurry prepared in the embodiments of the present invention has a stable neutralization ability in the acidic system of wet metallurgy. By adjusting the slurry adjustment parameters, it can achieve an equivalent substitution of 45% to 55% of lime.

[0045] Experiment Example 2: Neutralization Reaction Kinetics and pH Change Characteristics Experimental objective: To investigate the pH change pattern of dust removal slurry during the neutralization process and to analyze its differences from lime slurry in terms of reaction rate and reaction behavior.

[0046] I. Experimental Methods: Under the same initial acidity conditions, the dust removal slurry (concentration of 20 wt%) prepared according to Example 1 of the present invention and lime milk of the same concentration were added to the reaction system in batches. The pH changes of the system within different reaction times (0-4 min) were recorded and compared with the lime milk neutralization process.

[0047] II. Experimental Results The experimental results are shown in Table 1-2.

[0048] Table 1. Test data of neutralization experiment for 20% dust removal slurry

[0049] Table 2. Test data for neutralization experiment with 20% lime slurry.

[0050] The experimental data in Tables 1 and 2 show that the pH rise rate of the dust removal slurry of this invention is lower than that of lime slurry in the initial stage of the reaction. However, as the reaction time increases, the pH rises steadily and gradually, with no obvious local high pH peaks. In contrast, when using lime slurry of the same concentration for neutralization, the pH rises faster in the initial stage of the reaction than with the dust removal slurry. Furthermore, when the amount of lime slurry added is 190-200 ml, the pH of the system shows a rapid upward trend during the reaction. This indicates poor controllability and stability during the neutralization process, increasing the operational difficulty in its practical application to the neutralization of acidic slurries and tailings produced by hydrometallurgy.

[0051] Therefore, the dust removal slurry prepared by this invention exhibits a slow-release alkaline release characteristic during the neutralization process, which is beneficial to improving the controllability of the neutralization reaction and the stability of the system.

[0052] Experiment Example 3: Verification Experiment on the Iron and Aluminum Removal Capabilities of Dust Removal Slurry Experimental objective: To verify the ability of dust removal slurry to remove iron and aluminum impurities during the neutralization process in hydrometallurgy.

[0053] I. Experimental Methods Actual acidic mineral slurry was selected as the experimental object. It was neutralized by 20% lime milk and dust removal slurry with different equivalent ratios. After reaching the set pH, solid-liquid separation was carried out, and the content of elements such as Fe and Al in the filtrate was measured.

[0054] II. Experimental Results The experimental results are shown in Table 3.

[0055] Table 3 Test results of Fe and Al element removal capabilities

[0056] The experimental data in Table 3 show that, under the same endpoint pH conditions, the removal rate of iron and aluminum impurities by the dust removal slurry is basically equivalent to that of lime milk at the same concentration. The removal rate of Fe can reach over 99.9%, and the removal rate of Al is 95.43%, which is close to the removal rate of 95.54% of lime milk at the same concentration. This proves that the dust removal slurry prepared by this invention can meet the requirements of wet metallurgical impurity removal process.

[0057] The experimental data in Table 3 show that the dust removal slurry used in this invention has good iron and aluminum removal capabilities during the wet metallurgical neutralization process, without affecting the impurity removal effect.

[0058] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for neutralizing lime plant dust removal slurry in wet metallurgy, characterized in that, Includes the following steps: S1. The dust collected from the lime plant is digested and treated. S2. Prepare dust removal slurry; S3. Add the prepared dust removal slurry to the acidic slurry or tailings produced in the hydrometallurgical process, adjust the pH of the slurry, separate the solid and liquid components of the slurry, and complete the neutralization of the acidic slurry or tailings.

2. The method for using lime plant dust removal slurry for wet metallurgical neutralization as described in claim 1, characterized in that, The collected dust contains calcium oxide, calcium carbonate, and inert mineral components.

3. The method for neutralizing lime plant dust removal slurry in wet metallurgy as described in claim 1, characterized in that, The digestion process includes the following steps: pouring the collected dust into the digestion device and adding water for digestion.

4. The method for neutralizing lime plant dust removal slurry in wet metallurgy as described in claim 3, characterized in that, The amount of water added is 5-30% of the total mass of dust collected in the digester.

5. The method for using lime plant dust removal slurry for wet metallurgical neutralization as described in claim 1, characterized in that, The preparation of the dust removal slurry includes the following steps: adding water to the digested dust removal ash, stirring, and obtaining the dust removal slurry.

6. The method for neutralizing lime plant dust removal slurry in wet metallurgy as described in claim 5, characterized in that, The mass ratio of the dust to the added water is 1:(3~6).

7. The method for using lime plant dust removal slurry for wet metallurgical neutralization as described in claim 5, characterized in that, The stirring rate is 300~500 r / min, and the stirring time is 1~6 h.

8. The method for using lime plant dust removal slurry for wet metallurgical neutralization as described in claim 1, characterized in that, The solid content of the dust removal slurry is 10-30%.

9. The method for neutralizing lime plant dust removal slurry in wet metallurgy as described in claim 1, characterized in that, The neutralization effect of the dust removal slurry on acidic slurry or tailings generated during hydrometallurgical processes is 45-55% that of lime milk.

10. The application of a method for neutralizing lime plant dust removal slurry as described in any one of claims 1 to 9 in hydrometallurgical processes for adjusting the pH value of leachate and tailings.

Images