Process for the synergic recovery of carbon and valuable metals from carbon concentrate slags

Abstract

This invention discloses a synergistic recovery process for carbon and valuable metals from carbon concentrate slag. The process includes slurry pretreatment, flotation carbon extraction, direct tailings slurry leaching, solid-liquid separation, metal enrichment, and water recycling. By coupling flotation and wet leaching processes, this invention can simultaneously recover carbon components and valuable metals such as lead and zinc from carbon concentrate slag. Flotation tailings can be directly fed into the leaching process without dewatering and drying, and the leaching supernatant can be reused in the upstream slurry preparation stage. The overall process is simple, operates under mild conditions, and effectively reduces energy and fresh water consumption. It is suitable for the resource-based treatment of various carbon- and metal-containing solid wastes, such as coal washing tailings and carbonaceous slag from non-ferrous metal smelting.

Description

Technical Field

[0001] This invention belongs to the field of industrial solid waste resource utilization technology, specifically involving a synergistic recovery process of carbon and valuable metals from carbon concentrate slag. Background Technology

[0002] Carbon concentrate slag is a typical industrial solid waste generated in industries such as coal washing and non-ferrous metal smelting. The slag contains a certain proportion of fixed carbon components, along with various valuable metal elements such as lead, zinc, and iron. With the expansion of industrial production, the amount of carbon concentrate slag produced has been increasing year by year. Currently, most enterprises use stockpiling or landfill methods for disposal, which not only occupies a large amount of land resources but also easily causes secondary pollution of soil and groundwater, while also wasting carbon and metal resources.

[0003] Among the existing technologies for treating carbon concentrate slag, one type focuses on recovering carbon components, often using flotation processes for carbon enrichment. The resulting carbon concentrate can be used as fuel or industrial raw material, but valuable metals in the flotation tailings are not effectively recovered, resulting in resource waste. The other type focuses on recovering valuable metals, often using processes such as wet leaching and pyrometallurgical smelting to extract metals. However, the carbon components in the slag are not rationally utilized, and pyrometallurgical processes are energy-intensive and polluting, while wet processes have problems such as high reagent consumption and large wastewater discharge.

[0004] Some existing technologies attempt to recover carbon and metals simultaneously, but they generally suffer from poor process synergy: carbon recovery and metal recovery processes are independent of each other, requiring multiple dehydration, drying and transfer processes, resulting in long process flow and high energy consumption; residual reagents from the front-end flotation can adversely affect subsequent metal leaching, leading to a decrease in metal leaching efficiency; the wastewater generated from leaching cannot be directly reused in the front-end flotation process and needs to be treated separately, further increasing treatment costs and environmental pressure.

[0005] Therefore, developing a simple, highly collaborative, and low-cost process for the co-recovery of carbon and valuable metals from carbon concentrate slag is of great significance for improving the resource utilization level of this type of solid waste. Summary of the Invention

[0006] To address the aforementioned problems, the present invention aims to provide a synergistic recovery process for carbon and valuable metals from carbon concentrate slag, characterized by good metal recovery synergy, a short process, and low energy consumption and wastewater discharge.

[0007] This invention is achieved through the following technical solution: A process for the co-recovery of carbon and valuable metals from carbon concentrate slag includes the following steps: S1. Slurry pretreatment: Add water to carbon concentrate slag to prepare slurry of a set concentration, add adjuster and stir well, and adjust the pH of slurry to weakly alkaline; S2. Carbon extraction by flotation: Collector and frother are added sequentially to the pretreated slurry. After roughing, cleaning and scavenging flotation processes, carbon concentrate and flotation tailings are obtained respectively. S3. Tailings slurry leaching: The flotation tailings are directly adjusted to adjust the slurry concentration, leaching agent is added, and leaching is carried out under normal temperature and pressure to obtain leached slurry. S4. Solid-liquid separation: The leaching slurry is filtered and separated to obtain leaching solution and leaching residue respectively; S5. Metal enrichment and water circulation: Add a precipitant to the leachate to adjust the pH, and obtain valuable metal enriched slag through precipitation separation. The supernatant after separation is reused in the slurry preparation process of step S1.

[0008] Further, in step S1, the concentration of the slurry is 20%~30%; the adjusting agent is sodium carbonate, and its addition amount is 1kg / t~3kg / t of the dry weight of carbon concentrate slag; the pH of the slurry is adjusted to 7~9.

[0009] Further, in step S2, the collector is a mixture of kerosene and diesel oil, with a mass ratio of 1:1 to 2:1, and the total amount of collector added is 0.5 kg / t to 1.5 kg / t of the dry weight of carbon concentrate slag.

[0010] Further, in step S2, the foaming agent is pine oil, and its addition amount is 0.1 kg / t to 0.3 kg / t of the dry weight of carbon concentrate slag.

[0011] Furthermore, in step S2, the flotation process adopts a roughing, cleaning, and scavenging process. The roughing time is 3 to 5 minutes, the cleaning time for each stage is 2 to 4 minutes, and the scavenging time is 3 to 4 minutes. The scavenging foam is returned to the roughing inlet, and the cleaned tailings are returned to the next-level cleaning inlet.

[0012] Furthermore, in step S3, the mass concentration of the flotation tailings pulp is 15%~25%; the leaching agent is a sulfuric acid solution, and its addition amount is based on adjusting the pulp pH to 1.5~2.5.

[0013] Furthermore, in step S3, the stirring speed during leaching is 200 r / min to 300 r / min, and the leaching time is 60 min to 120 min.

[0014] Further, in step S5, the precipitant is a mixture of sodium hydroxide and sodium sulfide in a mass ratio of 3:1 to 5:1, and the pH of the slurry is adjusted to 8 to 9.

[0015] Furthermore, in step S5, the reuse ratio of the supernatant is 60% to 80% of the total water used for slurry preparation, and the remaining portion is supplemented with fresh water.

[0016] The beneficial effects of this invention are: 1. By adopting a coupled process of flotation carbon extraction and wet leaching enrichment of valuable metals, the simultaneous recovery of carbon components and valuable metals in carbon concentrate slag can be effectively achieved. 2. Flotation tailings can be directly mixed into leaching pulp without dewatering or drying, which can effectively simplify the process, reduce intermediate processing steps, and reduce energy consumption in the process. 3. By precisely controlling the pH of the upstream slurry and adapting the reagent system, the adverse effects of residual flotation reagents on the subsequent leaching process can be effectively reduced, ensuring the stability of metal leaching effect. 4. The supernatant after sedimentation and separation of the leachate can be directly reused in the upstream slurry preparation process, which can effectively reduce the consumption of fresh water and reduce the amount of wastewater discharged. 5. The entire process operates under normal temperature and pressure conditions, which is mild and can effectively reduce safety risks and equipment investment costs during operation. Detailed Implementation

[0017] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0018] The carbon concentrate slag used in this embodiment of the invention is taken from carbonaceous waste slag of a non-ferrous metal smelter. The slag has a fixed carbon content of about 28%, a lead content of about 1.2%, a zinc content of about 0.8%, and an iron content of about 6.5%. Example 1

[0019] This embodiment provides a process for the synergistic recovery of carbon and valuable metals from carbon concentrate slag, with the following steps: S1. Slurry pretreatment: Take 1000g of dry carbon concentrate slag, add water to prepare a slurry with a mass concentration of 25%, add 2g of sodium carbonate (equivalent to 2kg / t dry slag), stir for 5min to mix evenly, and measure the pH of the slurry to be 8.1; S2. Carbon extraction by flotation: Add 1g of kerosene and 0.5g of diesel oil to the slurry (total addition amount 1.5kg / t dry residue, kerosene:diesel = 2:1), stir for 2 minutes, then add 0.2g of pine oil (equivalent to 0.2kg / t dry residue), stir for 1 minute, and then perform one roughing, two cleaning, and one scavenging flotation; the roughing time is 4 minutes, the first cleaning time is 3 minutes, the second cleaning time is 2 minutes, and the scavenging time is 3 minutes; the scavenging froth is returned to the roughing inlet, and the cleaning tailings are returned to the previous cleaning inlet; finally, carbon concentrate and flotation tailings are obtained. S3. Tailings slurry conditioning and leaching: Water is added directly to the flotation tailings to adjust the mass concentration to 20%, sulfuric acid solution is added to adjust the pH of the slurry to 2.0, and the slurry is stirred and leached for 90 minutes at a speed of 250 r / min and at normal temperature and pressure to obtain the leaching slurry; S4. Solid-liquid separation: The leaching slurry is vacuum filtered to obtain leaching solution and leaching residue respectively; S5. Metal enrichment and water recycling: Add a mixture of sodium hydroxide and sodium sulfide (mass ratio 4:1) to the leachate, adjust the pH to 8.5, stir for 10 minutes and let it stand to settle, filter to obtain valuable metal enrichment slag, and reuse the supernatant in the slurry preparation process of step S1, with a reuse ratio of 70% of the total water consumption. Example 2

[0020] The process in this embodiment differs from that in Embodiment 1 in the following ways: In step S1, the slurry concentration is 20%, the sodium carbonate addition is 1 kg / t dry residue, and the slurry pH is 7.2; In step S2, the total collector addition is 0.5 kg / t dry residue, the kerosene:diesel ratio is 1:1, and the pine oil addition is 0.1 kg / t dry residue; the roughing time is 3 min, the cleaning time is 2 min per stage, and the scavenging time is 3 min; In step S3, the slurry concentration is 15%, the leaching pH is 1.5, the leaching time is 60 min, and the stirring speed is 200 r / min; In step S5, the precipitant mass ratio is 3:1, the pH is adjusted to 8.0, and the supernatant reuse rate is 60%. Example 3

[0021] The process in this embodiment differs from that in Embodiment 1 in the following ways: In step S1, the slurry concentration is 30%, the sodium carbonate addition is 3 kg / t dry residue, and the slurry pH is 8.9; In step S2, the total collector addition is 1.0 kg / t dry residue, the kerosene:diesel ratio is 1.5:1, and the pine oil addition is 0.3 kg / t dry residue; the roughing time is 5 min, the cleaning time is 4 min per stage, and the scavenging time is 4 min; In step S3, the slurry concentration is 25%, the leaching pH is 2.5, the leaching time is 120 min, and the stirring speed is 300 r / min; In step S5, the precipitant mass ratio is 5:1, the pH is adjusted to 9.0, and the supernatant reuse rate is 80%.

[0022] Comparative Example 1 This comparative example uses a conventional separate flotation carbon extraction process, with the following steps: the carbon concentrate slag is slurry adjusted to a concentration of 25%, sodium carbonate is added to adjust the pH to 8.0, 1.5 kg / t of kerosene and 0.2 kg / t of pine oil are added, and carbon concentrate is obtained through one roughing, two cleaning and one scavenging flotation. The tailings are directly discharged.

[0023] Comparative Example 2 This comparative example uses a conventional direct acid leaching process to recover metals. The steps are as follows: the carbon concentrate slag is slurryed to a concentration of 20%, sulfuric acid is added to adjust the pH to 2.0, leaching is carried out at room temperature for 90 minutes, the leaching solution is filtered, a precipitant is added to recover the metals, the leaching residue is discharged, and the wastewater is discharged after treatment.

[0024] The processing effects of the above embodiments and comparative examples were tested, and the results are shown in Table 1 below: Table 1

[0025] As shown in the table above, the synergistic recovery process described in this invention can effectively recover valuable metals such as lead and zinc from the slag while obtaining qualified carbon concentrate products. Compared with the flotation process alone, the carbon recovery effect is better, and metal resources can be recovered simultaneously. Compared with the direct acid leaching process, the metal recovery rate is higher, and the fresh water consumption is significantly reduced. All embodiments can stably achieve synergistic recovery of carbon and metals, and the water recycling effect is good. By adjusting the process parameters, it can be adapted to the treatment needs of carbon concentrate slag with different components.

[0026] The scope of protection of this invention is not limited to the technical solutions disclosed in the specific embodiments. Any modifications, equivalent substitutions, improvements, etc., made to the above embodiments based on the technical essence of this invention shall fall within the scope of protection of this invention.

Claims

1. A process for the synergistic recovery of carbon and valuable metals from carbon concentrate slag, characterized in that: Includes the following steps: S1. Slurry pretreatment: Add water to carbon concentrate slag to prepare slurry of a set concentration, add adjuster and stir well, and adjust the pH of slurry to weakly alkaline; S2. Carbon extraction by flotation: Collector and frother are added sequentially to the pretreated slurry. After roughing, cleaning and scavenging flotation processes, carbon concentrate and flotation tailings are obtained respectively. S3. Tailings slurry leaching: The flotation tailings are directly adjusted to adjust the slurry concentration, leaching agent is added, and leaching is carried out under normal temperature and pressure to obtain leached slurry. S4. Solid-liquid separation: The leaching slurry is filtered and separated to obtain leaching solution and leaching residue respectively; S5. Metal enrichment and water circulation: Add a precipitant to the leachate to adjust the pH, and obtain valuable metal enriched slag through precipitation separation. The supernatant after separation is reused in the slurry preparation process of step S1.

2. The co-recovery process of carbon and valuable metals from carbon concentrate slag according to claim 1, characterized in that: In step S1, the concentration of the slurry is 20%~30%; the adjuster is sodium carbonate, and its addition amount is 1kg / t~3kg / t of the dry weight of carbon concentrate slag; the pH of the slurry is adjusted to 7~9.

3. The co-recovery process of carbon and valuable metals from carbon concentrate slag according to claim 1, characterized in that: In step S2, the collector is a mixture of kerosene and diesel oil, with a mass ratio of 1:1 to 2:1, and the total amount of collector added is 0.5 kg / t to 1.5 kg / t of the dry weight of carbon concentrate slag.

4. The co-recovery process of carbon and valuable metals from carbon concentrate slag according to claim 1, characterized in that: In step S2, the foaming agent is pine oil, and its addition amount is 0.1 kg / t to 0.3 kg / t of the dry weight of carbon concentrate slag.

5. The co-recovery process of carbon and valuable metals from carbon concentrate slag according to claim 1, characterized in that: In step S2, the flotation process adopts a roughing, cleaning, and scavenging process. The roughing time is 3 to 5 minutes, the cleaning time for each stage is 2 to 4 minutes, and the scavenging time is 3 to 4 minutes. The scavenging froth is returned to the roughing inlet, and the cleaned tailings are returned to the next-level cleaning inlet.

6. The co-recovery process of carbon and valuable metals from carbon concentrate slag according to claim 1, characterized in that: In step S3, the mass concentration of the flotation tailings pulp is 15%~25%; the leaching agent is a sulfuric acid solution, and its addition amount is based on adjusting the pulp pH to 1.5~2.

5.

7. The co-recovery process of carbon and valuable metals from carbon concentrate slag according to claim 1, characterized in that: In step S3, the stirring speed during leaching is 200 r / min to 300 r / min, and the leaching time is 60 min to 120 min.

8. The co-recovery process of carbon and valuable metals from carbon concentrate slag according to claim 1, characterized in that: In step S5, the precipitant is a mixture of sodium hydroxide and sodium sulfide in a mass ratio of 3:1 to 5:1, and the pH of the slurry is adjusted to 8 to 9.

9. The co-recovery process of carbon and valuable metals from carbon concentrate slag according to claim 1, characterized in that: In step S5, the supernatant is reused at a rate of 60% to 80% of the total water used for slurry preparation, with the remainder being replenished with fresh water.

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