Method for extracting cassiterite by reselecting smelting waste slag

Abstract

The invention provides a method for extracting cassiterite through reselection of smelting waste residues, and belongs to the field of solid waste resource utilization. Tantalum-niobium wet smelting residues are subjected to water leaching pretreatment, soluble impurities are removed, and tin-grade-enriched water leaching residues are obtained; and the water leaching residues are subjected to size mixing and then centrifugal reselection, and tin concentrate is obtained. According to the method for recovering cassiterite from tantalum-niobium smelting slag, the defects in the prior art are overcome, the method is short in process, low in cost and capable of achieving ultrahigh recovery rate and high-grade enrichment at the same time, and the core of the technical scheme lies in that the synergistic effect between water leaching pretreatment and centrifugal reselection is found; according to the method, soluble impurities are removed through water leaching, the grade is preliminarily enriched, then the strong capturing capacity of a centrifugal force field on fine-fraction heavy minerals is combined, the high recovery rate and high-grade enrichment are achieved at the same time, the cassiterite recovery rate is larger than or equal to 85%, the final concentrate grade is larger than or equal to 20%, and the comprehensive enrichment ratio gt is achieved; and the index is far superior to that of the traditional reselection process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solid waste resource utilization, and particularly relates to a method for extracting cassiterite from smelting slag by gravity separation. BACKGROUND

[0002] Tantalum-niobium hydrometallurgy slag is a solid waste produced after extraction of tantalum and niobium, and usually contains cassiterite (SnO2) with a grade of about 2.5% to 4%. Effective recovery of the cassiterite has important economic value and environmental significance for improving resource utilization rate and reducing environmental risk.

[0003] However, the existing recovery technology has two major bottlenecks: first, the chemical composition of the slag is complex, and it is rich in a large amount of soluble salts and impurities such as iron. If the slag is directly subjected to gravity separation without pretreatment, the slurry environment will seriously interfere with the separation process, resulting in low efficiency; second, the cassiterite in the slag is finely disseminated, and the traditional gravity separation equipment (such as a shaking table) has limited capturing capacity for fine particles, resulting in serious loss of tin in tailings and generally less than 70% of the overall recovery rate, which is difficult to meet the economic requirements of industrial production.

[0004] Therefore, it is necessary to design a method for extracting cassiterite from smelting slag by gravity separation to solve the above problems. SUMMARY

[0005] In view of the technical problems in the background art, the present application provides a method for extracting cassiterite from smelting slag by gravity separation, which aims to solve the technical problems of low recovery rate and low concentrate grade in traditional gravity separation.

[0006] The present application provides a method for extracting cassiterite from smelting slag by gravity separation, which comprises the following steps: S1. Water immersion pretreatment is performed on the tantalum-niobium hydrometallurgy slag to remove soluble impurities, and a water immersion slag with enriched tin grade is obtained; S2. The water immersion slag is slurried and subjected to centrifugal gravity separation to obtain a tin concentrate.

[0007] As a further improvement of the present application, in step S1, the liquid-solid ratio of the water immersion pretreatment is (1-6):1.

[0008] As a further improvement of the present application, the water immersion temperature is 0-40℃, and the water immersion time is 1-2h.

[0009] As a further improvement of the present application, in step S2, the centrifugal force of the centrifugal gravity separation is 50-600G.

[0010] As a further improvement of the present application, the flow of the centrifugal gravity separation is one of once roughing, once roughing and once scavenging, once roughing and twice scavenging, and once roughing, once cleaning and once scavenging.

[0011] As a further improvement of the present application, in step S2, the pulp concentration of the water immersion slag after slurry preparation is 20-30%.

[0012] As a further improvement of the present application, the tin grade of the tin concentrate is not less than 20%, and the tin metal recovery rate is not less than 85%.

[0013] The beneficial effects of the present application are: The present application provides a method for smelting waste slag gravity separation to extract cassiterite. The method comprises the following steps: performing water immersion pretreatment on tantalum-niobium wet smelting slag to remove soluble impurities, thereby obtaining water immersion slag with enriched tin grade; and performing centrifugal gravity separation on the water immersion slag after slurry preparation, thereby obtaining tin concentrate. The present application overcomes the defects of the prior art, and provides a method for recovering cassiterite from tantalum-niobium smelting slag, which has a short process flow, low cost, and can simultaneously achieve ultra-high recovery rate and high grade enrichment. The core of the technical scheme is to find the synergistic effect between water immersion pretreatment and centrifugal gravity separation. By removing soluble impurities through water immersion pretreatment and preliminarily enriching the grade, and combining the strong capturing ability of the centrifugal force field to fine-grained heavy minerals, the method achieves the combination of high recovery rate and high grade enrichment. The cassiterite recovery rate is greater than or equal to 85%, the final concentrate grade is greater than or equal to 20%, and the comprehensive enrichment ratio is greater than 6 times, which is much better than the traditional gravity separation process.

[0014] The method for smelting waste slag gravity separation to extract cassiterite provided by the present application has a simple process flow and low cost. The entire process only needs two main steps, does not need to add expensive reagents, has low equipment investment and operating cost, and is very suitable for industrial application. The present application converts solid waste into high-value resources, and realizes the true transformation of waste into treasure.

[0015] The above description is only a summary of the technical scheme of the present application. In order to more clearly understand the technical means of the present application, the specific embodiments of the present application can be implemented in accordance with the content of the specification, and in order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the following will specifically describe the embodiments of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical scheme of the present application, the drawings used in the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creating any creative labor on the basis of these drawings.

[0017] Figure 1 The method for smelting waste slag gravity separation to extract cassiterite provided by the present application has a simple process flow and low cost. The entire process only needs two main steps, does not need to add expensive reagents, has low equipment investment and operating cost, and is very suitable for industrial application. The present application converts solid waste into high-value resources, and realizes the true transformation of waste into treasure. DETAILED DESCRIPTION

[0018] The technical solutions of the present application will be described in detail below with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, but cannot limit the protection scope of the present application.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present application; the terms "include" and "have" and any variations thereof in the specification and claims of the present application and the above description of drawings are intended to cover non-exclusive inclusion.

[0020] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present application. The occurrence of the phrase in various places in the specification does not necessarily all refer to the same embodiment, nor is it necessarily independent or alternative embodiments to each other. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0021] In the description of the embodiments of the present application, the term "a plurality of" refers to two or more (including two), and similarly, "a plurality of groups" refers to two or more groups (including two groups), and "a plurality of pieces" refers to two or more pieces (including two pieces).

[0022] Tin stone with a grade of about 2.5% to 4% is often contained in tantalum-niobium hydrometallurgy slag, and recovering the tin stone is of great significance to improve resource comprehensive utilization rate and reduce environmental risk. At present, the main technical bottleneck for recovering tin stone from such slag is that: (1) the chemical composition of the slag is complex, containing a large amount of soluble salts and impurities such as iron, and direct gravity separation is seriously disturbed; (2) the tin stone is finely disseminated, and the traditional gravity separation equipment (such as a shaking table) has low recovery efficiency for fine-grained tin stone, resulting in large tailings loss and generally less than 70% of the overall recovery rate.

[0023] In order to solve the technical problems of high cost, long process and unable to balance high recovery rate and high concentrate grade of the traditional recovery method, the present application provides a method for gravity separation of smelting slag to extract tin stone, wherein the soluble impurities are removed by water immersion and the grade is preliminarily enriched, and the strong capture ability of centrifugal force field to fine-grained heavy minerals is combined, so that the technical effect of simultaneously improving the tin stone recovery rate and the concentrate grade under the conditions of low cost and low energy consumption can be achieved.

[0024] The present application provides a method for gravity separation of smelting slag to extract tin stone, comprising the following steps: S1. Water immersion pretreatment is performed on the tantalum-niobium hydrometallurgy slag to remove soluble impurities, and a water immersion slag with enriched tin grade is obtained; S2. The water-immersed residue is thickened and then centrifugally reselected to obtain a tin concentrate.

[0025] In the technical scheme of the embodiments of the present application, since the tantalum-niobium hydrometallurgy slag contains a large amount of Na + , K + , Cl - , SO4 2- and other soluble salts, in water, these salts will quickly dissolve to form a solution with high ionic strength. When directly subjected to reselection, the high-salinity environment will significantly increase the viscosity of the ore slurry, and the high-viscosity ore slurry will hinder the speed difference in the density settlement of mineral particles, making it more difficult to separate the fine particles with an already not obvious density difference. Water immersion removes these salts by dissolving and removing them, restores the normal viscosity of water, and creates basic conditions for free settlement of minerals according to density. In addition, part of the iron in the slag may exist in the form of soluble ferrous sulfate (FeSO4), etc., and the water immersion process can remove it, reducing the complexity of subsequent separation. Through centrifugal reselection, the centrifugal concentrator generates a strong centrifugal force field through high-speed rotation, and the cassiterite particles can quickly overcome the interference of water flow resistance, etc., to achieve rapid separation from gangue minerals. Through the organic combination of the two core technologies of water immersion purification and centrifugal intensification, the two major difficulties of chemical interference and fine particle size faced in the recovery of cassiterite from tantalum-niobium hydrometallurgy slag are accurately solved, forming an innovative process route with a short process, low cost and high efficiency, which has extremely high technical value and industrial application prospect.

[0026] Further, in some embodiments, in step S1, the liquid-solid ratio of the water immersion pretreatment is (1-6):1, the water immersion temperature is 0-40℃, and the water immersion time is 1-2h.

[0027] In the technical scheme of the embodiments of the present application, the acid left in the tantalum-niobium smelting slag is used to effectively remove soluble impurities such as iron during the water immersion process, so that the cassiterite is preliminarily enriched in the solid. Sufficient water ensures that the waste slag particles are fully surrounded and infiltrated by water. If there is too little water, the system will become very viscous, and soluble salts will be difficult to diffuse from the interior of the particles to the main solution, resulting in incomplete desalination. Although a higher liquid-solid ratio can ensure more sufficient leaching, it increases the energy consumption of pumping and solid-liquid separation. The water immersion temperature and time ensure that the chemical reaction and mass transfer processes can be fully carried out at room temperature. Through water immersion pretreatment, the Sn grade is significantly improved from 2.5-4% to more than 10%.

[0028] Further, in some embodiments, in step S2, the centrifugal force of the centrifugal reselection is 50-600G.

[0029] In the technical scheme of the embodiment of the present application, the traditional reselection (such as a shaking table) relies on the earth gravity. For fine tin stone, the gravity suffered by the fine tin stone in water and the interference force such as Brown motion and water flow drag force are in the same order of magnitude, which leads to the failure of effective sedimentation separation. The centrifugal concentrator can amplify the gravity acceleration by 50 to 600 times through high-speed rotation, so that the sedimentation speed and separation efficiency of the tin stone particles in the centrifugal field are exponentially improved, thereby obtaining high-grade concentrate. Specifically, for coarse tin stone, a lower centrifugal force can be used because the gravity of the coarse tin stone itself is relatively large, and the strong centrifugal field is not needed for effective recovery, the separation precision is high, the gangue is not easy to be mixed, and the high-grade concentrate can be directly obtained; for fine tin stone, a higher centrifugal force is needed to separate the fine particles from the ore slurry, so as to realize high recovery rate.

[0030] Further, in some embodiments, the flow of the centrifugal reselection is one of once roughing, once roughing and once scavenging, once roughing and twice scavenging, and once roughing, once cleaning and once scavenging.

[0031] In the technical scheme of the embodiment of the present application, the modular processes such as roughing, scavenging and cleaning are flexibly configured to realize fine regulation and control of the recovery rate and concentrate grade. Specifically, the centrifugal reselection process can be one of once roughing, once roughing and once scavenging, once roughing and twice scavenging, and once roughing, once cleaning and once scavenging; and the centrifugal machine includes a horizontal centrifugal machine and a vertical centrifugal machine.

[0032] Further, in some embodiments, in step S2, the concentration of the ore slurry after the water immersion residue is adjusted is 20-30%.

[0033] In the technical scheme of the embodiment of the present application, at this concentration, the ore slurry is neither too dilute to waste the processing capacity, nor too thick to hinder the layering of particles, and there is enough space and suitable fluid environment between the particles to respond to the action of the centrifugal force, thereby realizing efficient separation.

[0034] Further, in some embodiments, the tin grade in the tin concentrate is not less than 20%, and the tin metal recovery rate is not less than 85%.

[0035] In the technical scheme of the embodiment of the present application, through the synergistic effect between the water immersion pretreatment and the centrifugal reselection, the high recovery rate and the high-grade enrichment are realized.

[0036] Some specific embodiments are listed below. It should be noted that the embodiments described below are exemplary and are used to explain the present application, and cannot be understood as a limitation of the present application. If the specific technology or condition is not specified in the embodiments, the technology or condition described in the literature in the art or according to the product manual is used. If the reagent or instrument is not specified by the manufacturer, it is a conventional product that can be obtained from the market.

[0037] Embodiment 1 The embodiment provides a method for extracting cassiterite from smelting waste residues, and the tin (Sn) grade of tantalum-niobium hydrometallurgy residues is 3.2%. The method comprises the following steps: S1. Take 1 ton of tantalum-niobium hydrometallurgy residues, add clean water at a liquid-solid ratio of 3:1 at 25 DEG C, stir and leach for 1 h, remove soluble impurities, and obtain about 200 kg of water leaching residues after filtration. The tin grade of the water leaching residues is enriched to 15.8% through detection. S2. The water leaching residues are adjusted into a slurry with a concentration of 25%, and are fed into a horizontal centrifugal concentrator for centrifugal gravity separation. A "one roughing and one scavenging" process is adopted, the roughing centrifugal force intensity is 80G, and roughing concentrate and roughing tailings are obtained. The roughing tailings are fed into another centrifugal concentrator for scavenging, the scavenging centrifugal force intensity is 100G, and scavenging concentrate and final tailings are obtained. The roughing concentrate and the scavenging concentrate are combined to obtain tin concentrate, the weight of which is about 130 kg, the tin grade is 22.5%, and the tin metal recovery rate is 91.41%.

[0038] Embodiment 2 The embodiment provides a method for extracting cassiterite from smelting waste residues, and the tin (Sn) grade of tantalum-niobium hydrometallurgy residues is 3.2%. The method comprises the following steps: S1. Take 1 ton of tantalum-niobium hydrometallurgy residues, add clean water at a liquid-solid ratio of 3:1 at 25 DEG C, stir and leach for 1 h, remove soluble impurities, and obtain about 200 kg of water leaching residues after filtration. The tin grade of the water leaching residues is enriched to 15.8% through detection. S2. The water leaching residues are adjusted into a slurry with a concentration of 25%, and are fed into a horizontal centrifugal concentrator for centrifugal gravity separation. A "one roughing and one scavenging" process is adopted, the roughing centrifugal force intensity is 80G, and roughing concentrate and roughing tailings are obtained. The roughing tailings are fed into another centrifugal concentrator for scavenging, the scavenging centrifugal force intensity is 100G, and scavenging concentrate and final tailings are obtained. The roughing concentrate and the scavenging concentrate are combined to obtain tin concentrate, the weight of which is about 130 kg, the tin grade is 22.5%, and the tin metal recovery rate is 91.41%.

[0039] The final tin concentrate obtained through centrifugal gravity separation has a weight of about 115 kg, a tin grade of 25.1%, and a tin metal recovery rate of 90.20%.

[0040] Embodiment 3 The embodiment provides a method for extracting cassiterite from smelting waste residues, and the tin (Sn) grade of tantalum-niobium hydrometallurgy residues is 3.2%. The method comprises the following steps:

[0041] The final tin concentrate obtained through centrifugal gravity separation has a weight of about 115 kg, a tin grade of 25.1%, and a tin metal recovery rate of 90.20%.

[0042] Comparative Example 1 Comparative Example 1 provides a method for extracting cassiterite from smelting slag by gravity separation. Compared with Example 1, the only difference is that no water immersion pretreatment is performed, and other experimental parameters and conditions are basically the same as those of Example 1, which will not be repeated here.

[0043] The final tin concentrate product obtained weighs about 250 kg, but the tin grade is only 6.80%, and the tin metal recovery rate is only 53.13%. Due to the lack of water immersion pretreatment, soluble salts and impurities seriously interfere with centrifugal separation, resulting in a sharp decrease in recovery rate and concentrate grade.

[0044] Comparative Example 2 Comparative Example 2 provides a method for extracting cassiterite from smelting slag by gravity separation. Compared with Example 1, the only difference is that a traditional shaking table is used for gravity separation, and other experimental parameters and conditions are basically the same as those of Example 1, which will not be repeated here.

[0045] The final tin concentrate obtained weighs about 30 kg, with a tin grade of 32.66% and a total tin metal recovery rate of 30.62%. Although the traditional shaking table can obtain high-grade concentrate, it has poor recovery ability for fine-grained cassiterite, low comprehensive recovery rate, and cannot achieve high recovery rate and high grade at the same time.

[0046] In summary, the method for extracting cassiterite from smelting slag provided by the present application can stably obtain tin concentrate with a grade higher than 20% and a recovery rate higher than 85% through the synergistic effect of water immersion pretreatment and centrifugal gravity separation, and by optimizing the process parameters, successfully realizing the unity of high recovery rate and high grade. Comparative Example 1 lacks the key water immersion pretreatment step, resulting in serious chemical interference, and the recovery rate and grade are greatly reduced; Comparative Example 2 uses a traditional shaking table, which has insufficient capture ability for fine-grained cassiterite, resulting in extremely low recovery rate and failing to meet the requirements of industrial production. The method proposed by the present application provides a low-cost, short-flow and efficient and reliable technical path for the resource utilization of cassiterite in tantalum-niobium hydrometallurgy slag, and has significant industrial application value and environmental protection benefits.

[0047] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and embodiments having the same technical idea and playing the same role within the scope of the technical solution of the present application are also included in the technical scope of the present application. In addition, within the scope of the main idea of the present application, various modifications of the embodiments that can be thought of by those skilled in the art, and other ways constructed by combining part of the constituent elements of the embodiments are also included in the scope of the present application.

Claims

1. A method for gravity separation extraction of cassiterite from smelting waste, characterized in that, Includes the following steps: S1. Water leaching pretreatment is performed on tantalum-niobium hydrometallurgical slag to remove soluble impurities and obtain water-leached slag enriched with tin grade; S2. The water-leached residue is slurried and then centrifuged to obtain tin concentrate.

2. The method for extracting cassiterite from smelting waste slag according to claim 1, characterized in that, In step S1, the liquid-to-solid ratio of the water immersion pretreatment is (1~6):

1.

3. The method for extracting cassiterite from smelting waste slag according to claim 2, characterized in that, The water immersion temperature is 0~40℃, and the immersion time is 1~2 hours.

4. The method for extracting cassiterite from smelting waste slag according to claim 1, characterized in that, In step S2, the centrifugal force for centrifugal reselection is 50~600G.

5. The method for extracting cassiterite from smelting waste slag according to claim 4, characterized in that, The centrifugal re-selection process can be one of the following: one coarse selection, one coarse and one scan, one coarse and two scans, or one coarse, one fine, and one scan.

6. The method for extracting cassiterite from smelting waste slag according to claim 1, characterized in that, In step S2, the slurry concentration after water leaching residue slurry preparation is 20-30%.

7. The method for extracting cassiterite from smelting waste slag according to claim 1, characterized in that, The tin concentrate has a tin grade of not less than 20% and a tin metal recovery rate of not less than 85%.

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