Cyclic chromium separation process

Abstract

The invention discloses a circular chromium separation process which comprises the following steps: sequentially carrying out ore washing and first-section cyclone separation on raw ore to obtain first-section cyclone overflow and first-section cyclone underflow, and carrying out low-intensity magnetic separation treatment on the first-section cyclone underflow to obtain first chromium middling; the first-section rotational flow underflow is sequentially subjected to low-intensity magnetic separation and high-intensity magnetic separation treatment, and then high-intensity magnetic separation non-magnetic substances and high-intensity magnetic separation magnetic substances are obtained; the high-intensity magnetic separation magnetic substance is sequentially subjected to spiral chute grading, multi-section table grading, low-intensity magnetic separation and spiral grading, and chromium concentrate, second chromium middling, second low-intensity magnetic separation middling and mixed light mineral aggregate are obtained; and after the mixed light mineral aggregate and the high-intensity magnetic separation non-magnetic substance are mixed, ball-milled and stirred, second-stage cyclone separation is carried out, and obtained second-stage cyclone underflow and second low-intensity magnetic separation middling are reused for the high-intensity magnetic separation procedure after ball-milling is carried out on the second-stage cyclone underflow and the second low-intensity magnetic separation middling. According to the method, the chromite in the laterite-nickel ore is separated through the combined process of multi-stage magnetic separation, the spiral chute, multi-stage table classification and multi-stage cyclone separation, so that the recovery rate and the grade of the obtained chromium concentrate are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of mineral processing, in particular to a circulating chromium processing technology. Background Art

[0002] Currently, hydrometallurgical smelting of laterite nickel ore through high-pressure acid leaching holds great promise in the new energy industry. However, high-pressure acid leaching requires expensive corrosion-resistant equipment. The presence of spinel-type chromite in laterite nickel ore can severely abrade the anti-corrosion coating of hydrometallurgical equipment, increasing equipment costs and posing safety risks. Furthermore, post-high-pressure acid leaching, impurities such as iron, aluminum, and chromium must be removed to ensure the quality of the resulting hydrometallurgical product.

[0003] To reduce the negative impact of chromite on laterite nickel ore hydrometallurgy, chromite from laterite nickel ore must be beneficiated and impurities removed. Furthermore, this beneficiation and chromium removal process can also yield a portion of qualified chromium concentrate, achieving comprehensive resource utilization. Existing technologies typically use single gravity separation or magnetic separation to separate chromium from laterite nickel ore. However, these single separation methods often result in significant chromium losses and produce a low-grade chromium concentrate.

[0004] Therefore, it is necessary to provide a circulating chromium separation process that improves the grade and recovery rate of chromium concentrate. Summary of the Invention

[0005] In view of this, the present application provides a circulating chromium separation process to solve the problem of how to improve the grade and recovery rate of chromium concentrate in the laterite nickel ore beneficiation process.

[0006] In order to achieve the above technical objectives, this application adopts the following technical solutions: The present application provides a cyclic chromium selection process, comprising: S1. The ore is sequentially subjected to a washing process and a cyclone separation to obtain a cyclone overflow and a cyclone underflow. The cyclone underflow is subjected to a weak magnetic separation to obtain the first chromium ore. The cyclone underflow is sequentially subjected to a weak magnetic separation and a strong magnetic separation to obtain a strong magnetic separation non-magnetic material and a strong magnetic separation magnetic material. S2. The strong magnetic separation magnetic material is sequentially subjected to spiral chute classification, multi-stage shaking table classification, and then weak magnetic separation and spiral classification to obtain chromium concentrate, second chromium ore, second weak magnetic separation ore and mixed light ore; S3. After mixing the mixed light ore with the strong magnetic separation non-magnetic material and stirring it by ball milling, a two-stage cyclone separation is performed. The overflow of the second cyclone is mixed with the overflow of the first cyclone and used to prepare the high-pressure leaching solution. The second cyclone underflow and the second weak magnetic separation ore are mixed and ball milled and reused in the strong magnetic separation process in step S1.

[0007] Preferably, in step S1, the magnetic field strength of the weak magnetic separation is 1000-2000 GS; the magnetic field strength of the strong magnetic separation is 10000-20000 GS.

[0008] Preferably, in step S1, the specific steps of the first-stage cyclone separation include: introducing the raw ore into a first-stage cyclone after the ore washing process for first-stage cyclone separation to obtain a first-stage cyclone overflow and a first-stage cyclone underflow, and the first-stage cyclone overflow is processed according to step S3.

[0009] Preferably, in step S1, the specific steps of weak magnetic separation are: introducing a section of cyclone underflow into a first weak magnetic separator for first weak magnetic separation to obtain weak magnetic separation magnetic material and weak magnetic separation non-magnetic material, introducing the weak magnetic separation magnetic material into a weak magnetic machine pump pool and then classifying it through a middling spiral classifier to obtain a first chromium middling ore.

[0010] Preferably, in step S1, the specific steps of high-intensity magnetic separation are: feeding the weak-magnetic non-magnetic material into the high-intensity magnetic separator for high-intensity magnetic separation to obtain high-intensity magnetic non-magnetic material and high-intensity magnetic magnetic material, and processing the high-intensity magnetic non-magnetic material according to step S3.

[0011] Preferably, in step S2, the specific steps of spiral chute classification are: collecting the strong magnetic separation magnetic materials into the spiral chute to obtain chute light ore and chute heavy ore, and post-processing the chute light ore as a component of the mixed light ore in step S3.

[0012] Preferably, in step S2, the multi-stage shaking table classification includes a single-stage shaking table classification and a two-stage shaking table classification in sequence; the step of the single-stage shaking table classification is: the heavy ore material in the chute is introduced into the single-stage shaking table for single-stage shaking table classification to obtain a single-stage shaking table light ore material and a single-stage shaking table heavy ore material; the step of the two-stage shaking table classification is: the heavy ore material in the single-stage shaking table is introduced into the second-stage shaking table for two-stage shaking table classification to obtain a second-stage shaking table light ore material, a second-stage shaking table medium ore material, and a second-stage shaking table heavy ore material; the single-stage shaking table light ore material and the second-stage shaking table light ore material are both used as components of the mixed light ore material in step S3 for post-processing.

[0013] Preferably, in step S2, the steps of weak magnetic separation and spiral classification are: the heavy ore material of the second-stage shaking table is introduced into the second weak magnetic separator for second weak magnetic separation to obtain a first weak magnetic concentrate and a first weak magnetic separated ore, and the first weak magnetic concentrate is introduced into the first spiral classifier for first spiral classification to obtain a chromium concentrate; the medium ore material of the second-stage shaking table is introduced into the third weak magnetic separator for third weak magnetic separation to obtain a second weak magnetic concentrate and a second weak magnetic separated ore, the second weak magnetic separated ore is processed according to step S3, and the second weak magnetic concentrate and the first weak magnetic separated ore are introduced into the second spiral classifier together for second spiral classification to obtain a second chromium ore.

[0014] Preferably, in step S3, the mixed light ore and the strong magnetic separation non-magnetic material are mixed and then poured into a ball mill stirring tank for ball milling and stirring, and then poured into a second-stage cyclone separator for second-stage cyclone separation to obtain a second-stage cyclone underflow and a second-stage cyclone overflow. The second-stage cyclone underflow and the second weak magnetic separation ore are poured into a ball mill for ball milling and then returned to the strong magnetic separator to continue the strong magnetic separation process.

[0015] Preferably, in step S3, the specific steps of preparing the high-pressure leaching solution are: passing the overflow of the first cyclone through a first impurity removal screen for one-stage impurity removal and then transporting it to the finished product tank and then to the raw ore slurry storage tank; passing the overflow of the second cyclone through a second impurity removal screen for two-stage impurity removal and then transporting it to the raw ore slurry storage tank; and the mixture in the raw ore slurry storage tank is poured into a thickener containing a flocculant for solid-liquid separation to obtain the high-pressure leaching solution.

[0016] The beneficial effects of the present application are as follows: the present application separates chromite from laterite nickel ore through a combined process of multi-stage magnetic separation, spiral chute, multi-stage shaking table classification, and multi-stage cyclone separation. The recovery rate of the obtained chromium concentrate and chromium middlings is high, and the grade of the chromium concentrate is high (greater than or equal to 36%), which is beneficial to reducing the chromium removal pressure in the wet smelting process of laterite nickel ore and is beneficial to the comprehensive utilization of the chromium element. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the process flow chart of this application. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0019] The embodiments and control examples of the present application all use laterite nickel ore from a tropical rainforest climate island near the equator in Indonesia. The main valuable metal elements of the ore are Ni, Fe and Co, and impurities such as Ca, Mg, Cr2O3 and SiO2 are also present. The presence of these impurities will increase the acid consumption of hydrometallurgy and form a large amount of acid leaching tailings. The purpose of the present application is to separate chromium from different mineral phases and improve the grade of chromium concentrate, so as to improve the comprehensive utilization rate of laterite nickel ore.

[0020] Based on this, the present invention was created.

[0021] The present application provides a cyclic chromium selection process, comprising: S1. The ore is sequentially subjected to a washing process and a cyclone separation to obtain a cyclone overflow and a cyclone underflow. The cyclone underflow is subjected to a weak magnetic separation to obtain the first chromium ore. The cyclone underflow is sequentially subjected to a weak magnetic separation and a strong magnetic separation to obtain a strong magnetic separation non-magnetic material and a strong magnetic separation magnetic material. S2. The strong magnetic separation magnetic material is sequentially subjected to spiral chute classification, multi-stage shaking table classification, and then weak magnetic separation and spiral classification to obtain chromium concentrate, second chromium ore, second weak magnetic separation ore and mixed light ore; S3. After mixing the mixed light ore with the strong magnetic separation non-magnetic material and stirring it by ball milling, a two-stage cyclone separation is performed. The overflow of the second cyclone is mixed with the overflow of the first cyclone and used to prepare the high-pressure leaching solution. The second cyclone underflow and the second weak magnetic separation ore are mixed and ball milled and then reused in the strong magnetic separation process in step S1.

[0022] The principle of the present application is that, before step S2, the present application sequentially performs weak magnetic separation and strong magnetic separation on a section of cyclone bottom flow, first uses weak magnetic separation to recover the first chromium middling, and then uses strong magnetic separation to further improve the grade of chromite. This combined process can not only improve the recovery rate of chromite concentrate, but also screen out more chromium middlings, significantly reduce the chromium content in the subsequent high-pressure leaching stock solution, and reduce the pressure of high-pressure leaching stock solution to remove chromium. In addition, the inventors found that one of the reasons for the low recovery rate and grade of chromite is that the mixed light ore and strong magnetic separation non-magnetic material still contain chromite embedded in the chromite. Therefore, the present application will obtain the second section of cyclone bottom flow and the second weak magnetic separation ore after ball milling and reuse it in the strong magnetic separation process in step S1. By ball milling, the monomer dissociation degree of chromite encapsulated in limonite is improved, so that the encapsulated chromite is separated and subjected to strong magnetic separation again, which is beneficial to the subsequent separation and recovery of chromium, further improving the recovery rate of chromite concentrate.

[0023] In some embodiments, in step S1, the specific steps of ore washing include: using a heavy-duty plate feeder to transport the laterite nickel ore to a drum ore washer to remove gravel with a particle size of 5-10 cm, and then processing it through a double-helical scrubber and a linear vibrating screen to remove gravel with a particle size of 2-5 cm to obtain gravel-free ore.

[0024] In this embodiment, gravel removal is first performed on the raw ore to reduce the interference of gravel in the subsequent mineral processing.

[0025] In some embodiments, in step S1, the magnetic field strength of the weak magnetic separation is 1000-2000 GS; the magnetic field strength of the strong magnetic separation is 10000-20000 GS.

[0026] In this embodiment, the differences in density and magnetic properties between chromite and other chromium-containing ore phases (such as limonite, spinel, and silicate) are utilized to first perform weak magnetic separation and then perform strong magnetic separation on a section of cyclonic underflow; weak magnetic separation and strong magnetic separation are achieved by setting different magnetic field intensities.

[0027] In some embodiments, in step S1, the specific steps of the first-stage cyclone separation include: introducing the raw ore into a first-stage cyclone after the ore washing process for first-stage cyclone separation, obtaining a first-stage cyclone overflow and a first-stage cyclone underflow, and processing the first-stage cyclone overflow according to step S3.

[0028] In this embodiment, the washed ore is separated into a cyclone overflow and a cyclone underflow after a cyclone separation. Since the grades of Ni and Cr2O3 do not change synchronously with the particle size, most of the chromium-containing impurities are separated in the cyclone underflow.

[0029] In some embodiments, in step S1, the specific steps of weak magnetic separation are: a section of cyclone bottom flow is introduced into a first weak magnetic separator for first weak magnetic separation to obtain weak magnetic separation magnetic material and weak magnetic separation non-magnetic material, the weak magnetic separation magnetic material is introduced into a weak magnetic machine pump pool and then classified by a middling spiral classifier to obtain a first chromium middling.

[0030] In some embodiments, in step S1, the specific steps of strong magnetic separation are: the weak magnetic separation non-magnetic material is fed into the strong magnetic separator for strong magnetic separation to obtain strong magnetic separation non-magnetic material and strong magnetic separation magnetic material, and the strong magnetic separation non-magnetic material is processed according to step S3.

[0031] In this embodiment, low-intensity magnetic separation is first used to recover the first chromium middlings, and then high-intensity magnetic separation is used to further improve the grade of the chromite. This combined process not only improves the recovery rate of the chromium concentrate, but also screens out more chromium middlings, significantly reducing the chromium content in the subsequent high-pressure leaching solution and reducing the pressure of the high-pressure leaching solution.

[0032] In some embodiments, in step S2, the specific steps of spiral chute classification are: collecting the strong magnetic separation magnetic material into the spiral chute to obtain chute light ore and chute heavy ore, and post-processing the chute light ore as a component of the mixed light ore in step S3.

[0033] In this embodiment, the obtained light ore material in the chute is introduced into a ball mill stirring tank and then subjected to a second-stage cyclone separation; the obtained heavy ore material in the chute contains both valuable metals and a chromium-containing ore phase.

[0034] In some embodiments, in step S2, the multi-stage shaking table grading includes a first-stage shaking table grading and a second-stage shaking table grading in sequence; the step of the first-stage shaking table grading is: the heavy ore material in the chute is introduced into the first-stage shaking table for first-stage shaking table grading to obtain a first-stage shaking table light ore material and a first-stage shaking table heavy ore material; the step of the second-stage shaking table grading is: the heavy ore material in the first-stage shaking table is introduced into the second-stage shaking table for second-stage shaking table grading to obtain a second-stage shaking table light ore material, a second-stage shaking table medium ore material, and a second-stage shaking table heavy ore material; the first-stage shaking table light ore material and the second-stage shaking table light ore material are both used as components of the mixed light ore material in step S3 for post-processing.

[0035] In some embodiments, in step S2, the steps of weak magnetic separation and spiral classification are as follows: the heavy ore material of the second-stage shaking table is introduced into the second weak magnetic separator for the second weak magnetic separation to obtain the first weak magnetic concentrate and the first weak magnetic medium, and the first weak magnetic concentrate is introduced into the first spiral classifier for the first spiral classification to obtain the chromium concentrate; the medium ore material of the second-stage shaking table is introduced into the third weak magnetic separator for the third weak magnetic separation to obtain the second weak magnetic concentrate and the second weak magnetic medium, the second weak magnetic medium is ball-milled and then reused in the strong magnetic separation process to continue the strong magnetic separation, and the second weak magnetic concentrate and the first weak magnetic medium are introduced into the second spiral classifier together for the second spiral classification to obtain the second chromium medium.

[0036] In some embodiments, in step S3, the mixed light ore and the strong magnetic separation non-magnetic material are mixed and then poured into a ball mill stirring tank for ball milling and stirring, and then poured into a two-stage cyclone separator for two-stage cyclone separation to obtain a two-stage cyclone bottom flow and a two-stage cyclone overflow. The second-stage cyclone bottom flow and the second weak magnetic separation ore are poured into a ball mill for ball milling and then returned to the strong magnetic separator to continue the strong magnetic separation process.

[0037] In some embodiments, the mixed light ore includes chute light ore, first-stage shaking table light ore, and second-stage shaking table light ore.

[0038] Preferably, in step S3, the specific steps of preparing the high-pressure leaching solution are: passing the overflow of the first cyclone through a first impurity removal screen for one-stage impurity removal and then transporting it to the finished product tank and then to the raw ore slurry storage tank; passing the overflow of the second cyclone through a second impurity removal screen for two-stage impurity removal and then transporting it to the raw ore slurry storage tank; and the mixture in the raw ore slurry storage tank is poured into a thickener containing a flocculant for solid-liquid separation to obtain the high-pressure leaching solution.

[0039] The present invention is further described below through specific examples.

[0040] Example 1 A cyclic chromium selection process comprises the following steps: S1. The laterite nickel ore is conveyed by a heavy-duty plate feeder to a drum ore washer to remove gravel with a particle size of 35 mm or more. The ore is then processed by a double-screw scrubber and a linear vibrating screen to remove gravel with a particle size of 2 mm or more. The ore is then fed into a mixing tank and a slurry pump to obtain a de-graveled ore (washed ore). The Cr2O3 grade in the de-graveled ore is determined to be 3.21%, with a recovery rate of 59.73%. The de-graveled ore is then introduced into a first-stage cyclone for first-stage cyclone separation, obtaining a first-stage cyclone overflow. and a cyclone underflow; the cyclone underflow is introduced into a first weak magnetic separator for first weak magnetic separation to obtain weak magnetic separation magnetic material and weak magnetic separation non-magnetic material; the weak magnetic separation magnetic material is introduced into a weak magnetic machine pump pool and then classified by a middling spiral classifier to obtain a first chromium middling; the Cr2O3 grade of the first chromium middling is determined to be 17.6% and the recovery rate is 30.2%; the weak magnetic separation non-magnetic material is introduced into a strong magnetic separator for strong magnetic separation to obtain strong magnetic separation non-magnetic material and strong magnetic separation magnetic material; wherein, the magnetic field strength of the first weak magnetic separation is 1500 GS; the magnetic field strength of the strong magnetic separation is 10000 GS; S2. The strong magnetic separation magnetic material is fed into a spiral chute to obtain light ore and heavy ore. The heavy ore is fed into a first-stage shaking table for first-stage shaking classification to obtain light ore and heavy ore. The heavy ore is fed into a second-stage shaking table for second-stage shaking classification to obtain light ore, medium ore, and heavy ore. The heavy ore is fed into a second-stage weak magnetic separator for second-stage weak magnetic separation to obtain first-stage weak magnetic separation concentrate and first-stage weak magnetic separation concentrate. The first-stage weak magnetic separation concentrate is fed into a first spiral classifier for The first spiral classification yielded a chromium concentrate, the Cr2O3 grade of which was determined to be 38.06%, with a recovery rate of 19.86%. The ore from the second-stage shaking table was fed into a third weak magnetic separator for third weak magnetic separation to yield a second weak magnetic concentrate and second weak magnetic middling. The second weak magnetic concentrate and the first weak magnetic middling were then fed together into a second spiral classifier for second spiral classification to yield a second chromium middling. The Cr2O3 grade of the second chromium middling was determined to be 26.1%, with a recovery rate of 8.3%. The magnetic field strengths for the second weak magnetic separation were 1300 GS, and 1200 GS for the third weak magnetic separation.

[0041] S3. The light ore material from the chute, the light ore material from the first shaking table and the light ore material from the second shaking table are mixed as mixed light ore material with the non-magnetic material separated by strong magnetic separation, and then introduced into a ball mill stirring tank for ball milling and stirring, and then introduced into a second cyclone separator for second cyclone separation to obtain a second cyclone underflow and a second cyclone overflow. The second cyclone underflow and the ore separated by the second weak magnetic separation are introduced into a ball mill for ball milling and then recycled into a strong magnetic separator to continue the strong magnetic separation process; the overflow of the first cyclone is passed through a first impurity removal screen for a first stage of impurity removal and then transported to a finished product tank and then to a raw ore slurry storage tank; the overflow of the second cyclone is passed through a second impurity removal screen for a second stage of impurity removal and then transported to a raw ore slurry storage tank; the mixture in the raw ore slurry storage tank is introduced into a thickener containing a flocculant for solid-liquid separation to obtain a high-pressure leaching stock solution. The chromium content of the high-pressure leaching stock solution is determined to be 0.02%.

[0042] Comparative Example 1 A circulating chromium separation process is the same as Example 1 in other contents, except that the weak magnetic separation and strong magnetic separation in step S1 are not included; and step S3 does not include ball milling the obtained second-stage cyclone underflow and the second weak magnetic separation ore and recycling them to the second-stage cyclone separation process.

[0043] It was determined that the Cr2O3 grade in the gravel ore was 3.21%, with a recovery rate of 59.73%; the Cr2O3 grade in the chromium concentrate was 35.32%, with a recovery rate of 7.51%; the Cr2O3 grade in the second chromium middling was 17.4%, with a recovery rate of 10.54%; and the chromium content in the high-pressure leaching solution was 1.9%.

[0044] Comparative Example 2 A cyclic chromium separation process is the same as that of Example 1 except that the weak magnetic separation and strong magnetic separation in step S1 are not included.

[0045] It was determined that the Cr2O3 grade in the gravel ore was 3.21%, with a recovery rate of 59.73%; the Cr2O3 grade in the chromium concentrate was 35.43%, with a recovery rate of 7.35%; the Cr2O3 grade in the second chromium middling was 17.1%, with a recovery rate of 10.33%; and the chromium content in the high-pressure leaching solution was 0.7%.

[0046] Comparative Example 3 A cyclic chromium separation process, the other contents of which are the same as those of Example 1, except that the weak magnetic separation in step S1 is not included.

[0047] It was determined that the Cr2O3 grade in the gravel ore was 3.21%, with a recovery rate of 59.73%; the Cr2O3 grade in the chromium concentrate was 36.05%, with a recovery rate of 8.64%; the Cr2O3 grade in the second chromium middling was 19.4%, with a recovery rate of 12.54%; and the chromium content in the high-pressure leaching solution was 0.38%.

[0048] Comparative Example 4 A cyclic chromium separation process is the same as that of Example 1 except that the high-intensity magnetic separation in step S1 is not included.

[0049] It was determined that the Cr2O3 grade in the gravel ore was 3.21%, with a recovery rate of 59.73%; the Cr2O3 grade in the first chromium middlings was 17.5%, with a recovery rate of 30.5%; the Cr2O3 grade in the chromium concentrate was 36.44%, with a recovery rate of 8.09%; the Cr2O3 grade in the second chromium middlings was 21.34%, with a recovery rate of 13.31%; and the chromium content in the high-pressure leaching solution was 0.41%.

[0050] Comparative Example 5 A recycling chromium separation process is the same as that of Example 1 except that step S3 does not include ball milling the obtained second-stage cyclone underflow and the second weak magnetic separation ore and then recycling them to the second-stage cyclone separation process.

[0051] It was determined that the Cr2O3 grade in the gravel ore was 3.21%, with a recovery rate of 59.73%; the Cr2O3 grade in the first chromium middlings was 17.5%, with a recovery rate of 30.4%; the Cr2O3 grade in the chromium concentrate was 38.22%, with a recovery rate of 19.14%; the Cr2O3 grade in the second chromium middlings was 26.8%, with a recovery rate of 7.9%; and the chromium content in the high-pressure leaching solution was 1.4%.

[0052] The above embodiments and comparative examples illustrate that the present application separates chromite from laterite nickel ore through a combined process of multi-stage magnetic separation, spiral chute, multi-stage shaking table classification, and multi-stage cyclone separation. The recovery rates of the obtained chromite concentrate and chromium middlings are high, the chromite concentrate recovery rate reaches 14-20%, and the grade of the chromite concentrate is high (greater than or equal to 36%). This solution is beneficial to reducing the chromium removal pressure during the hydrometallurgical smelting process of laterite nickel ore and is beneficial to the comprehensive utilization of the chromium element.

[0053] The above are only preferred specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or replacements that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A cyclic chromium selection process, characterized in that: include: S1. The ore is sequentially subjected to a washing process and a cyclone separation to obtain a cyclone overflow and a cyclone underflow. The cyclone underflow is subjected to a weak magnetic separation to obtain a first chromium middling. The cyclone underflow is sequentially subjected to a weak magnetic separation and a strong magnetic separation to obtain a strong magnetic separation non-magnetic material and a strong magnetic separation magnetic material. S2. The strong magnetic separation magnetic material is sequentially subjected to spiral chute classification, multi-stage shaking table classification, and then weak magnetic separation and spiral classification to obtain chromium concentrate, second chromium ore, second weak magnetic separation ore and mixed light ore; S3. After mixing the mixed light ore with the strong magnetic separation non-magnetic material and stirring by ball milling, perform two-stage cyclone separation, mix the overflow of the second stage cyclone with the overflow of the first stage cyclone and use it to prepare high-pressure leaching stock solution, and mix the second stage cyclone underflow and the second weak magnetic separation ore and then reuse them in the strong magnetic separation process in step S1 after mixing and ball milling.

2. The cyclic chromium separation process according to claim 1, characterized in that: In step S1, the magnetic field strength of the weak magnetic separation is 1000-2000 GS; the magnetic field strength of the strong magnetic separation is 10000-20000 GS.

3. The cyclic chromium selection process according to claim 1, characterized in that: In step S1, the specific steps of the first stage cyclone separation include: introducing the raw ore into a first stage cyclone after the ore washing process for first stage cyclone separation to obtain a first stage cyclone overflow and a first stage cyclone underflow, and the first stage cyclone overflow is processed according to step S3.

4. The cyclic chromium selection process according to claim 3, characterized in that: In step S1, the specific steps of weak magnetic separation are: a section of cyclone bottom flow is introduced into a first weak magnetic separator for first weak magnetic separation to obtain weak magnetic separation magnetic material and weak magnetic separation non-magnetic material, the weak magnetic separation magnetic material is introduced into a weak magnetic machine pump pool and then classified by a middling spiral classifier to obtain a first chromium middling ore.

5. The cyclic chromium selection process according to claim 4, characterized in that: In step S1, the specific steps of high-intensity magnetic separation are: the weak-magnetic non-magnetic material is introduced into the high-intensity magnetic separator for high-intensity magnetic separation to obtain high-intensity magnetic non-magnetic material and high-intensity magnetic magnetic material, and the high-intensity magnetic non-magnetic material is processed according to step S3.

6. The cyclic chromium selection process according to claim 1, characterized in that: In step S2, the specific steps of the spiral chute classification are: the strong magnetic separation magnetic material is collected into the spiral chute to obtain chute light ore and chute heavy ore, and the chute light ore is used as a component of the mixed light ore in step S3 for post-processing.

7. The cyclic chromium selection process according to claim 6, characterized in that: In step S2, the multi-stage shaking table classification includes a first-stage shaking table classification and a second-stage shaking table classification; The first stage shaking table classification step is: the heavy ore material in the chute is collected into the first stage shaking table for first stage shaking table classification to obtain the first stage shaking table light ore material and the first stage shaking table heavy ore material; The two-stage shaking table classification step comprises: transferring the heavy ore from the first-stage shaking table to the second-stage shaking table for second-stage shaking table classification to obtain light ore from the second-stage shaking table, medium ore from the second-stage shaking table, and heavy ore from the second-stage shaking table; The light ore material from the first-stage shaking table and the light ore material from the second-stage shaking table are both used as components of the mixed light ore material in step S3 for post-processing.

8. The cyclic chromium selection process according to claim 7, characterized in that: In step S2, the steps of weak magnetic separation and spiral classification are as follows: the heavy ore material of the second-stage shaking table is introduced into the second weak magnetic separator for the second weak magnetic separation to obtain the first weak magnetic concentrate and the first weak magnetic separated ore, and the first weak magnetic concentrate is introduced into the first spiral classifier for the first spiral classification to obtain chromium concentrate; the medium ore material of the second-stage shaking table is introduced into the third weak magnetic separator for the third weak magnetic separation to obtain the second weak magnetic concentrate and the second weak magnetic separated ore, and the second weak magnetic separated ore is processed according to step S3; the second weak magnetic concentrate and the first weak magnetic separated ore are introduced into the second spiral classifier together for the second spiral classification to obtain the second chromium ore.

9. The cyclic chromium selection process according to claim 1, characterized in that: Step S3 specifically includes: mixing the mixed light ore with the strong magnetic separation non-magnetic material and then merging it into a ball mill stirring tank for ball milling and stirring, and then merging it into a second-stage cyclone separator for second-stage cyclone separation to obtain a second-stage cyclone underflow and a second-stage cyclone overflow, and merging the second-stage cyclone underflow and the second weak magnetic separation ore into a ball mill for ball milling and then returning it to the strong magnetic separator to continue the strong magnetic separation process.

10. The cyclic chromium selection process according to claim 9, characterized in that: In step S3, the specific steps of preparing the high-pressure leaching solution are as follows: the overflow of the first cyclone is passed through a first impurity removal screen for a first stage of impurity removal and then transported to the finished product tank and then to the raw ore slurry storage tank; the overflow of the second cyclone is passed through a second impurity removal screen for a second stage of impurity removal and then transported to the raw ore slurry storage tank; the mixture in the raw ore slurry storage tank is collected into a thickener containing a flocculant for solid-liquid separation to obtain the high-pressure leaching solution.

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