Method for recovering zinc in high-silicon high-calcium low-grade zinc oxide

Abstract

The invention discloses a method for recovering zinc in high-silicon high-calcium low-grade zinc oxide, and belongs to the technical field of mineral processing. After sulphide ore flotation operation is carried out on high-silicon high-calcium low-grade zinc oxide ore, zinc oxide flotation operation is carried out through a sodium sulfide-fatty amine method, then fatty acid defoaming-fine selection operation is carried out on zinc rough concentrate, and zinc oxide concentrate is obtained. Aiming at the problems of serious ore pulp argillization of the zinc ore, poor separation effect of a conventional process, low concentrate quality and the like, the method advantages of fatty amine and fatty acid are fully utilized, organic combination is carried out, the method has the advantages of simple process, high adaptability and the like, and efficient recovery of the zinc ore difficult to treat is effectively realized.

Description

Technical Field

[0001] This invention relates to a method for recovering zinc from high-silicon, high-calcium, low-grade zinc oxide, belonging to the field of mineral processing technology. Background Technology

[0002] my country has abundant zinc oxide ore reserves, but the ore composition is complex, with more lean ore than rich ore. Flotation is the main method for enriching zinc oxide ore. The main zinc oxide minerals include smithsonite, hemimorphite, and zeolite, which are characterized by strong surface hydrophilicity, high crystal stability, and severe influence from soluble salts, making the flotation recovery of these minerals very difficult.

[0003] Currently, the sodium sulfide-fatty amine method and the sodium carbonate-fatty acid method are the two main approaches to recovering zinc oxide ore. The sodium sulfide-fatty amine method has advantages such as high recovery rate and short process, but fatty amines such as dodecylamine and octadecylamine have extremely strong foaming ability. Coupled with the severe mudification commonly found in zinc oxide ore, this method suffers from severe foaming problems, ultimately leading to large amounts of foam accumulation, making middlings recycling difficult and causing separation failure. Patent application number 202411734483.8 discloses a slurry conditioning and flotation method for gypsum-containing zinc oxide ore. By adding calcium ion chelating agents, sodium carbonate, and sodium sulfide to condition the slurry, and using fatty amines for collection, it effectively alleviates the impact of soluble calcium salts on the flotation of zinc oxide ore. Furthermore, the short process design reduces middlings recycling. However, it does not fundamentally solve the foaming problem caused by the use of fatty amines, and the concentrate quality from only one roughing operation is poor. Patent application number 202310307320.0 discloses a zinc oxide mineral flotation collector and its preparation method and application. By synthesizing a collector with R-NH-C-COONa by combining fatty amines with monochloroacetic acid and emulsifiers, and using sodium carbonate and sodium silicate as modifiers, the recovery of high-silica zinc oxide ore is effectively achieved. However, due to the short process, the concentrate quality is still low. At the same time, the carboxyl groups introduced in the collector have obvious selectivity defects when processing high-calcium zinc oxide ore. Summary of the Invention

[0004] To address the challenges of foaming difficulties in the fatty amine flotation of zinc oxide ores and the significant impact of calcium ions in the fatty acid flotation process, this invention provides a method for recovering zinc from high-silicon, high-calcium, low-grade zinc oxide, effectively achieving the recovery of zinc oxide minerals through flotation.

[0005] The technical solution of this invention is as follows: This invention uses sufficient sodium sulfide to activate zinc oxide minerals, and combines appropriate amounts of calcium-containing mineral inhibitors such as starch, slurry dispersant sodium hexametaphosphate and water glass to adjust the slurry. The sodium sulfide-fatty amine method is used to ensure sufficient zinc mineral recovery rate. For the large amount of zinc-rich flotation foam generated, the foam can be defoamed by rinsing with heated sodium oleate solution. The slurry after defoaming is collected and then finely selected to improve the concentrate grade, thereby realizing the recovery of zinc minerals from high-calcium and high-silicon zinc oxide ore.

[0006] A preferred method for recovering zinc from high-silicon, high-calcium, low-grade zinc oxide comprises the following steps: (1) After crushing, grinding and classifying the low-grade zinc oxide ore, a flotation slurry with a content of 80% of -200 mesh is obtained, and then sulfide ore flotation is carried out; (2) The slurry after flotation of sulfide ore in step (1) is introduced into stirred tank I and a conditioning agent is added. Then the slurry is introduced into stirred tank II and a collector is added to condition the slurry. (3) Perform a zinc oxide flotation operation on the slurry after step (2) to obtain zinc oxide crude concentrate froth and tailings I; (4) Use sodium oleate solution to spray-defoam and collect the zinc oxide crude concentrate foam from step (3), and perform a fine cleaning operation on the collected zinc crude concentrate slurry to obtain the final zinc oxide concentrate and tailings II.

[0007] The modifiers mentioned in step (2) include four types: sodium sulfide, starch, sodium hexametaphosphate and water glass. They are added by preparing a solution or turbid liquid. The dosage of sodium sulfide is 8-10 kg / t, and the dosage of the other modifiers is 300-500 g / t.

[0008] The collector mentioned in step (2) is octadecylamine acetate, and it is added by preparing a solution.

[0009] The duration of a single zinc oxide flotation operation in step (3) is 15 minutes.

[0010] The sodium oleate solution in step (4) is at a temperature of 65°C and is added at the flotation tank foam rinsing water point. The duration of one fine selection operation is 10 minutes.

[0011] Preferably, the collector in step (2) is octadecylamine acetate, which is added by preparing a solution according to the required mass and adding it at a dosage of 700-900 g / t.

[0012] Preferably, the duration of a single zinc oxide flotation operation in step (3) is 15 minutes.

[0013] Preferably, the sodium oleate solution in step (4) is at a temperature of 65°C, added at the flotation tank foam rinsing water point, and the fine selection operation lasts for 10 minutes, with a dosage of approximately 700-900 g / t.

[0014] The principle of this invention is as follows: In high-silicon, high-calcium, low-grade zinc oxide ore, a large amount of zinc oxide minerals and some siliceous gangues develop a negatively charged surface under the influence of a large amount of sodium sulfide. This surface then undergoes hydrolysis by octadecylamine to produce positively charged R-NH4. + Groups adsorb onto the surface of zinc minerals and siliceous gangues through electrostatic forces, generating stable zinc-rich foams.

[0015] Introducing heated sodium oleate solution into the above-mentioned stable foam can trigger multiple effects: (1) Sodium oleate and octadecylamine are anionic / cationic surfactants. Their coexistence will trigger antagonistic effects. Specifically, when the two are mixed, the surface activity will decrease due to electrostatic bonding molecular configuration conflicts, resulting in a decrease in the elasticity of the zinc-rich foam interface generated by octadecylamine.

[0016] (2) The hydrolyzed octadecylamine in the system forms a neutral electron pair with the free oleate ion, thereby destroying the stable foam structure generated by the octadecylamine itself.

[0017] (3) The adsorption of zinc atoms on the surface of zinc oxide by sodium oleate is a chemical adsorption behavior, which is more stable than the electrostatic adsorption of octadecylamine, thus allowing the defoamed zinc oxide minerals to retain flotation activity. This achieves the purpose of defoaming without losing the flotation activity of zinc oxide minerals.

[0018] Furthermore, the sodium oleate of this invention acts as an antifoaming agent for fatty amines at the foam rinsing water. This design is intended to prevent sodium oleate from prematurely contacting a large amount of calcium-containing minerals in the ore, which would otherwise cause calcium-containing gangue to float to the surface and deteriorate product indicators.

[0019] The hydrophobic foam layer is directly lost. The beneficial effects of this invention are: (1) Compared with the sodium sulfide-fatty amine method or modified fatty amine method, this invention utilizes heated sodium oleate spraying of zinc-rich foam, which effectively solves the problems of fatty amine foam accumulation and high circulating pressure of middlings, and achieves efficient recovery of zinc oxide minerals under the short process conditions of roughing and refining.

[0020] (2) Compared with the direct use of sodium carbonate-fatty acid method, the present invention adopts the sodium sulfide-fatty amine method to preferentially enrich zinc oxide and some siliceous gangue, which greatly reduces the contact between fatty acid collectors and calcium-containing minerals and effectively avoids the defect of poor fatty acid selectivity.

[0021] (3) The present invention provides a method for recovering zinc from high-silicon, high-calcium, and low-grade zinc oxide, which can effectively process this type of difficult-to-process zinc oxide ore. Through reasonable process design, it effectively addresses the problem of low product indicators caused by short process. Overall, it has the characteristics of simple process, high efficiency, low cost and strong applicability, and can provide a solid and reliable method for the development of this type of resource. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the process flow for Embodiments 1, 2, and 3 of the present invention; Figure 2 This is a schematic diagram of the process flow of Comparative Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the process flow of Comparative Example 2 of the present invention. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0024] Examples 1, 2, and 3: The applicability of this invention under different reagent dosage conditions was investigated based on the different zinc contents of the ore.

[0025] Mineral raw materials: The samples used in Examples 1, 2, and 3 are zinc oxide ore from a certain region in Nujiang Prefecture, Yunnan Province. The zinc grade is about 5.0-6.5%, the zinc oxidation rate is greater than 90%, the zinc mineral is mainly smithsonite, and the remainder is a small amount of sphalerite; the SiO2 content is about 22%, the main mineral is quartz; the CaO content is about 28%, the main calcium mineral is calcite.

[0026] The specific operating steps are as follows: (1) The ore sample was ground and classified to obtain a slurry with 80% of the content of -200 mesh. After the sulfide ore flotation operation, sulfide ore products and flotation tailings were obtained. (2) The flotation tailings from step (1) are introduced into the stirring tank I, and four kinds of modifiers are added, including sodium sulfide, starch, sodium hexametaphosphate and water glass, and the reaction time is 10 min. (3) Introduce the slurry from step (2) into the mixing tank II, add the collector octadecylamine acetate, and let it act for 10 minutes; (4) Perform a zinc oxide flotation operation on the slurry after completing step (3) for 15 minutes to obtain zinc oxide rough concentrate froth and tailings I; (5) Use a heated sodium oleate solution at 65°C to spray, defoam, and collect the zinc oxide crude concentrate foam from step (4); (6) Perform a fine cleaning operation on the collected zinc crude concentrate slurry. The fine cleaning operation lasts for 10 minutes to obtain zinc oxide concentrate and tailings II.

[0027] The workflow for Examples 1, 2, and 3 is as follows: Figure 1 As shown in Table 1, the pharmaceutical formulation is shown in Table 2, and the product indicators are shown in Table 2.

[0028] Table 1. Detailed Dosage of Pharmaceutical Agents in Examples 1, 2, and 3 Table 2 Product Indicators for Examples 1, 2, and 3 Table 2 shows the product indicators for Examples 1, 2, and 3, indicating that the zinc concentrate obtained by processing this type of zinc oxide ore using the method of the present invention has a zinc grade greater than 25% and a zinc recovery rate greater than 77%. The results demonstrate that the present invention provides an open-circuit method for recovering zinc minerals from high-silicon, high-calcium, low-grade zinc oxide ore, which is well-suited to this type of difficult-to-process zinc oxide ore and features simple process operation and excellent product indicators.

[0029] Comparative Example 1 Comparative Example 1 investigated the applicability of the sodium sulfide-fatty amine method to this type of zinc oxide ore. The mineral raw materials were basically the same as in Example 1, and the specific implementation method is as follows: (1) The ore sample was ground and classified to obtain a slurry with 80% of the content of -200 mesh. After the sulfide ore flotation operation, sulfide ore products and flotation tailings were obtained.

[0030] (2) The flotation tailings from step (1) are introduced into the stirring tank I. Add four types of modifiers, including sodium sulfide, starch, sodium hexametaphosphate and water glass. The amount of sodium sulfide is 8 kg / t, and the amount of the other modifiers is 300 g / t. The reaction time is 10 min.

[0031] (3) Introduce the slurry from step (2) into the mixing tank II, add 700g / t of octadecylamine acetate as a collector, and let it act for 10min.

[0032] (4) Perform a zinc oxide flotation operation on the slurry after completing step (3) for 15 minutes to obtain zinc oxide crude concentrate froth and tailings.

[0033] (5) The zinc oxide crude concentrate foam from step (4) is subjected to a fine selection operation by adding 2000g / t sodium sulfide and 200g / t octadecylamine acetate for 10 minutes to obtain zinc oxide concentrate and middlings. The middlings are returned to the zinc oxide roughing operation to form a closed loop.

[0034] Comparative Example 1 Workflow is as follows Figure 2 As shown in Table 3, the product specifications are as follows.

[0035] Table 3 Comparative Example 1 Product Indicators Table 3 shows the product index data of Comparative Example 1. After three closed-circuit cycles, the zinc grade of the zinc oxide concentrate gradually decreased from 25.69% to 8.63%, and the zinc recovery rate decreased from 62.23% to 49.97%. This phenomenon fully demonstrates the problems of severe foam accumulation and poor middlings circulation in the sodium sulfide-fatty amine process, which leads to separation failure in closed-circuit operations.

[0036] Comparative Example 2 Comparative Example 2 investigated the applicability of the sodium carbonate-fatty amine method to this type of zinc oxide ore. The mineral raw materials were basically the same as in Example 1, and the specific implementation method is as follows: (1) The ore sample was ground and classified to obtain a slurry with 80% of the content of -200 mesh. After the sulfide ore flotation operation, sulfide ore products and flotation tailings were obtained.

[0037] (2) The flotation tailings from step (1) are introduced into the stirring tank I and four kinds of modifiers are added, including sodium carbonate, starch, sodium hexametaphosphate and water glass. The amount of sodium carbonate is 15 kg / t, the amount of water glass is 3 kg / t, and the amount of starch and sodium hexametaphosphate is 300 g / t. The reaction time is 5 min.

[0038] (3) Introduce the slurry from step (2) into the mixing tank II, add 800g / t of sodium oleate as a collector, and let it act for 5 minutes.

[0039] (4) The slurry from step (3) is subjected to one roughing, three cleaning and two scavenging operations. The roughing operation lasts for 10 minutes and the remaining operations last for 6 minutes. The intermediate mineral products are returned in the order of operations to form a closed loop, and finally zinc oxide concentrate and tailings are obtained.

[0040] (5) For the rough concentrate after the roughing operation, the type and amount of the modifier added for the fine beneficiation operation I are: 5 kg / t of sodium carbonate and 1 kg / t of water glass. No reagents are added for fine beneficiation operations II and III.

[0041] (6) For tailings after roughing operation, the types and amounts of modifiers and collectors added for scavenging operation I are: sodium carbonate 2kg / t, water glass 500g / t, sodium oleate 300g / t; the types and amounts of modifiers and collectors added for scavenging operation I are: sodium carbonate 1kg / t, water glass 300g / t, sodium oleate 200g / t.

[0042] Comparative Example 2 Workflow is as follows Figure 3As shown in Table 4, the product specifications are as follows.

[0043] Table 4 Comparative Example 2 Product Indicators Table 4, comparing the product indicators of Example 2, shows that when this type of zinc oxide ore was treated using the sodium carbonate-fatty acid method, the zinc oxide concentrate obtained had a zinc grade of only 11.63% and a zinc recovery rate of 64.65%. The results indicate that the abundant calcium-containing minerals in this type of zinc oxide ore exhibit severe competitive adsorption behavior towards fatty acids, thus requiring a large amount of modifier for slurry preparation. Furthermore, when highly soluble gypsum minerals are present, the amount of modifier required increases further. Moreover, even with the aforementioned slurry preparation method to reduce the influence of calcium-containing minerals on the fatty acid collection of zinc oxide minerals, the product indicators remain far from ideal.

[0044] The product indicators of both the examples and comparative examples demonstrate that this invention fully combines the advantages of high recovery rate and good selectivity of the sodium sulfide-fatty amine method. Firstly, it fully recovers zinc oxide minerals through a single open-circuit process. Then, addressing the large amount of difficult-to-eliminate zinc-rich foam generated by fatty amines, it cleverly employs a heated fatty acid spray defoaming-refinement method, effectively avoiding the shortcomings of poor ore recycling and poor fatty acid selectivity in the sodium sulfide-fatty amine method. Overall, it features a simple process, high efficiency, low operating cost, and strong applicability, providing a solid and reliable method for the development of this type of resource.

[0045] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for recovering zinc from high-silicon, high-calcium, low-grade zinc oxide, characterized in that, The specific steps are as follows: (1) After crushing, grinding and classifying low-grade zinc oxide ore, flotation slurry with a content of 80-85% of -200 mesh is obtained. Then, sulfide ore flotation is carried out to obtain sulfide ore products and flotation tailings. (2) Introduce the flotation tailings after lead mineral flotation in step (1) into stirred tank I and add conditioning agent, and then introduce the slurry into stirred tank II and add collector to condition the slurry; (3) Perform a zinc oxide flotation operation on the slurry after step (2) to obtain zinc oxide crude concentrate froth and tailings I; (4) Use sodium oleate solution to spray-defoam and collect the zinc oxide crude concentrate foam from step (3), and perform a fine cleaning operation on the collected zinc crude concentrate slurry to obtain the final zinc oxide concentrate and tailings II.

2. The method for recovering zinc from high-silicon, high-calcium, low-grade zinc oxide according to claim 1, characterized in that: The modifiers mentioned in step (2) include four types: sodium sulfide, starch, sodium hexametaphosphate and water glass. They are added by preparing a solution or turbid liquid. The dosage of sodium sulfide is 8-10 kg / t, and the dosage of the other modifiers is 300-500 g / t.

3. The method for recovering zinc from high-silicon, high-calcium, low-grade zinc oxide according to claim 1, characterized in that: The collector mentioned in step (2) is octadecylamine acetate, which is added by preparing a solution and the dosage is 700-900g / t.

4. The method for recovering zinc from high-silicon, high-calcium, low-grade zinc oxide according to claim 1, characterized in that: The duration of a single zinc oxide flotation operation in step (3) is 15 minutes.

5. The method for recovering zinc from high-silicon, high-calcium, low-grade zinc oxide according to claim 1, characterized in that: The sodium oleate solution in step (4) is at a temperature of 65°C and is added at the flotation tank foam rinsing water point. The duration of one fine selection operation is 10 minutes, and the dosage is approximately 700-900 g / t.

Images