A method of recovering iron concentrate from a floatation iron tailings

Abstract

The application belongs to the technical field of mineral processing, and specifically discloses a method for recovering iron concentrate from a flotation iron tailing, which comprises the following steps: step (1), slurry pretreatment: inputting the flotation iron tailing into a stirring barrel, adding water to adjust the mass concentration of the slurry to 25%-40%, and adding a dispersing agent and an activator into the stirring barrel in sequence, fully stirring and mixing for 15-30 min to obtain pretreated slurry; step (2), heavy dressing of the feed: uniformly feeding the pretreated slurry into a suspension cone surface concentrator for rough separation; and step (3), heavy separation: performing fine separation through a flat table concentrator to obtain iron concentrate and final tailings. The technical scheme disclosed by the application can improve the dispersibility of the slurry and the surface properties of the minerals through specific reagent pretreatment, thereby strengthening the heavy separation process and improving the recovery index of the iron concentrate.

Description

Technical Field

[0001] This invention belongs to the field of mineral processing technology, specifically relating to a method for recovering iron concentrate from flotation iron tailings, and more particularly to a method for efficiently recovering iron concentrate from flotation iron tailings by adding reagents to regulate the properties of the slurry and combining it with gravity separation equipment. Background Technology

[0002] With the continuous mining of iron ore resources, large quantities of iron ore tailings from ore dressing plants are stockpiled, not only occupying land resources but also posing potential environmental pollution risks. Furthermore, these tailings often still contain a certain amount of iron minerals, and the iron mineral composition varies greatly depending on the properties of the original ore and the beneficiation process. For example, the iron grade in magnetic separation tailings is around 8%, while the iron grade in flotation tailings often reaches 10-25%. Therefore, compared with tailings discharged from other beneficiation processes, secondary recovery of iron minerals from flotation iron tailings has high economic value.

[0003] Currently, gravity separation is one of the commonly used processes for recovering iron minerals from flotation iron tailings, with commonly used equipment such as shaking tables, spiral sluices, or vibrating separators. Iron tailings obtained after flotation are generally characterized by fine particle size and a high content of associated clay minerals (such as ferrous carbonate, kaolinite, and montmorillonite). These fine clay minerals interact with residual flotation reagents, easily covering the surface of iron minerals or forming slime agglomerates, resulting in two significant adverse effects: first, the foamy pulp has excessive adhesion, affecting the uniform distribution of pulp in subsequent re-concentration operations (especially gravity separation); second, the poor dispersion of iron minerals and clay impurities under van der Waals forces leads to their mixing, significantly reducing the efficiency of density and particle size separation during gravity separation. Directly treating such tailings using traditional gravity separation methods often results in difficulties in improving concentrate grade and low recovery rates. Summary of the Invention

[0004] The purpose of this invention is to provide a method for recovering iron concentrate from flotation iron tailings. By pretreating with specific reagents, the dispersibility of the slurry and the surface properties of the minerals are improved, thereby enhancing the gravity separation process and improving the recovery index of iron concentrate from flotation iron tailings.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for recovering iron concentrate from flotation iron tailings includes the following steps: Step (1) Slurry pretreatment: Input the flotation iron tailings into the mixing tank, add water to adjust the slurry mass concentration to 25%~40%; add dispersant and activator to the mixing tank in sequence, stir and mix for 15~30 minutes to obtain pretreated slurry; Step (2) Gravity separation feeding: The pretreated slurry is fed evenly into the gravity separation equipment for roughing; Step (3) Gravity separation: High-grade iron concentrate and final tailings are obtained by fine separation through gravity separation equipment.

[0006] Based on the above technical solution, the flotation iron tailings are tailings discharged after the main metal is extracted by the flotation process, which contain clay gangue minerals; the total iron grade of the flotation tailings is 10%~25%, and the content of particles <0.074mm is 70%~90%; the iron minerals in the flotation iron tailings are hematite, magnetite and gangue minerals, of which hematite accounts for 10%~30%, magnetite accounts for 2%~10%, and gangue minerals account for 60%~88%, based on a total mass percentage of 100%.

[0007] Based on the above technical solution, the dispersant in step (1) is sodium hexametaphosphate or water glass. The dispersant can selectively adsorb onto the surface of clay minerals and iron minerals, increase the electrostatic repulsion between mineral particles, effectively solve the problem of heterogeneous aggregation between clay minerals and iron minerals, and allow iron minerals to be released from the encapsulation of clay impurities, thereby improving the dispersibility of mineral particles.

[0008] Based on the above technical solution, the amount of dispersant used in step (1) is 500~1500g / t dry tailings.

[0009] Based on the above technical solution, the activator in step (1) is selected from at least one of ammonium bicarbonate, ammonium sulfate, and oxalic acid. The role of the activator is to clean or adjust the active sites on the surface of iron minerals, eliminate the adverse effects of residual flotation reagents (such as collectors and inhibitors) on the surface of iron minerals, increase the hydrophilicity of the surface of iron minerals or improve the hydration film structure of foam in the pulp, and reduce the mechanical inclusion of gangue minerals caused by foam or adhesion during the gravity separation process.

[0010] Based on the above technical solution, the amount of activator used in step (1) is 200~800g / t dry tailings.

[0011] Based on the above technical solution, the gravity separation equipment in steps (2) and (3) is selected from at least one of the following: a suspended cone concentrator, a spiral chute, a centrifuge, and a flat shaking table.

[0012] Based on the above technical solution, when using a suspended conical concentrator for roughing, the feed concentration is 20%~35%, which can obtain rough concentrate and tailings; then the rough concentrate is concentrated and fed into a flat shaking table for fine selection. The shaking table stroke is 8~15mm and the stroke rate is 280~350 times / minute, finally obtaining high-grade iron concentrate.

[0013] Based on the above technical solution, when using a flat shaking table for roughing and cleaning, the feed concentration is 25%~40%, the shaking table stroke is 8~15mm, and the number of strokes is 280~350 times / minute, to obtain high-grade iron concentrate.

[0014] Based on the above technical solution, the grade of the high-grade iron concentrate is 60%~65%, the iron concentrate yield is 8%~12%, the tailings grade is 10%~13%, and the iron recovery rate is 30%~40%.

[0015] The principle of this invention lies in the combined action of dispersants and activators. On the one hand, it dissociates the mechanical inclusions of fine-grained iron minerals and clay minerals, effectively utilizing the liberation degree of individual iron minerals. On the other hand, it eliminates abnormal foaming and adhesion phenomena caused by residual reagents. After this treatment, the slurry enters the gravity field equipment, where the iron minerals, due to their higher density, form clear settling trajectories, while the less dense clay particles remain suspended and are discarded, thus significantly improving the separation accuracy of gravity separation.

[0016] Beneficial effects The technical solution disclosed in this invention solves the technical problem of poor dispersion of clay minerals and iron minerals in flotation iron tailings, significantly reducing mechanical inclusions in the gravity separation process; at the same time, it eliminates the abnormal foam adhesion phenomenon caused by residual reagents, ensuring stable fluidized separation of the slurry on the gravity separation equipment bed; the technical solution has a simple process, low reagent cost, and can effectively improve the grade and recovery rate of iron concentrate, realizing the secondary utilization of tailings resources; the suspension vibrating concentrator and shaking table can be used separately or in combination according to the properties of the iron tailings raw materials, which can give full play to the advantages of the large processing capacity of the suspension vibrating concentrator and the high selection accuracy of the shaking table. Attached Figure Description

[0017] Figure 1 This is a process flow diagram of Embodiment 1 of the present invention. Detailed Implementation

[0018] To make the objectives and technical solutions of this invention clearer, the following embodiments are provided for further explanation. However, the scope of protection of this invention is not limited to these embodiments; the embodiments are merely for illustrative purposes. Those skilled in the art should understand that any changes or equivalent substitutions that do not depart from the concept of this invention are included within the scope of protection of this invention.

[0019] Unless otherwise specified, all reagents and raw materials used in this invention are obtained through purchase.

[0020] Example 1 This embodiment processes a flotation iron tailings with a total iron grade of 17.5% and a particle size <0.074mm accounting for 75%. The iron minerals in the flotation iron tailings are hematite, magnetite, and gangue minerals, with hematite accounting for 18%, magnetite accounting for 2%, and gangue minerals accounting for 80%. Among the gangue minerals, quartz accounts for 55%, clay minerals account for 32%, and the remainder is unavoidable impurities. Among the clay minerals, kaolinite accounts for 60%, illite accounts for 30%, and the remainder is unavoidable impurities.

[0021] according to Figure 1 The process flow is as follows, with specific operating steps: Step (1) Slurry pretreatment: Take 1000 kg of dry iron tailings from flotation, add water to prepare a slurry with a slurry concentration of 30%, and put it into a mixing tank; add 800 g / t of sodium hexametaphosphate (based on dry ore) to the mixing tank, stir for 3 minutes, then add 500 g / t of ammonium bicarbonate, and continue stirring for 5 minutes to obtain the pretreated slurry; Step (2) Gravity separation feed: The pretreated slurry is fed into the vibrating cone concentrator for roughing through a slurry pump. The feed concentration is 32%, and a rough concentrate with a yield of 18.5% and a grade of 35.2% is obtained. Step (3) Gravity separation: After the above crude concentrate is concentrated to a mass concentration of 40%, it is fed into a flat shaking table for fine separation. The shaking table stroke is 12 mm and the stroke is 320 times / minute. Finally, an iron concentrate with a yield of 9.6% and a grade of 62.5% is obtained. The tailings grade is reduced to 12.7%, and the iron recovery rate reaches 34.3%. The indicators of this embodiment are significantly better than the process used in Comparative Example 1.

[0022] Comparative Example 1 The difference from Example 1 is that the direct gravity separation process (using only suspension and shaking table) without adding any reagents (sodium hexametaphosphate, ammonium bicarbonate) yielded a concentrate grade of only 52.1% and a recovery rate of 30.5%.

[0023] Example 2 This embodiment processes a flotation iron tailings with a high clay content, the original tailings grade being 10.8%.

[0024] The specific steps are as follows: Step (1) Slurry pretreatment: Add water to the flotation iron tailings to adjust the slurry to a mass concentration of 28%, then add 1200g / t of water glass (dispersant) and 600g / t of ammonium sulfate (activator) in sequence, and stir thoroughly for 5 minutes; Step (2) Gravity separation feeding and separation: The pretreated slurry is directly fed into a flat shaking table for a first-stage gravity separation. The shaking table stroke is 10 mm, and the stroke is 300 times / minute. In one step, the iron concentrate grade is 50.2% and the tailings grade is 7.6%. After testing, it was found that after adding reagents, the slurry on the shaking table surface was clearly zoned, the concentrate zone had no bubbling phenomenon, and the mineral flow was smooth.

[0025] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for recovering iron concentrate from flotation iron tailings, characterized in that, Includes the following steps: Step (1) Slurry pretreatment: Input the flotation iron tailings into the mixing tank, add water to adjust the slurry mass concentration to 25%~40%; add dispersant and activator to the mixing tank in sequence, stir and mix for 15~30 minutes to obtain pretreated slurry; Step (2) Gravity separation feeding: The pretreated slurry is fed evenly into the gravity separation equipment for roughing; Step (3) Gravity separation: High-grade iron concentrate and final tailings are obtained by fine separation through gravity separation equipment.

2. The method according to claim 1, characterized in that, The flotation iron tailings are tailings discharged after the main metal is extracted by the flotation process, which contain clay gangue minerals; the total iron grade of the flotation tailings is 10%~25%, and the content of particles <0.074mm is 70%~90%; the iron minerals in the flotation iron tailings are hematite, magnetite and gangue minerals, of which hematite accounts for 10%~30%, magnetite accounts for 2%~10%, and gangue minerals account for 60%~88%, based on a total mass percentage of 100%.

3. The method according to claim 1, characterized in that, The amount of dispersant used in step (1) is 500~1500g / t dry tailings.

4. The method according to claim 1, characterized in that, The amount of activator used in step (1) is 200~800g / t dry tailings.

5. The method according to claim 1, characterized in that, The gravity separation equipment in steps (2) and (3) is selected from at least one of the following: a suspended cone concentrator, a spiral chute, a centrifuge, and a flat shaking table.

6. The method according to claim 1, characterized in that, When using a suspended conical concentrator for roughing, the feed concentration is 20%~35%, which can obtain rough concentrate and tailings. The rough concentrate is then concentrated and fed into a flat shaking table for fine cleaning. The shaking table stroke is 8~15mm and the stroke rate is 280~350 times / minute, finally obtaining high-grade iron concentrate.

7. The method according to claim 1, characterized in that, When using a flat shaking table for roughing and cleaning, the feed concentration is 25%~40%, the shaking table stroke is 8~15mm, and the stroke rate is 280~350 times / minute to obtain high-grade iron concentrate.

8. The method according to claim 1, characterized in that, The high-grade iron concentrate has a grade of 60% to 65%, an iron concentrate yield of 8% to 12%, a tailings grade of 10% to 13%, and an iron recovery rate of 30% to 40%.

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