Process for recycling chromium from lateritic nickel ores

Abstract

The application provides a circulating chrome separation process of laterite nickel ore, which can separate chromite in the laterite nickel ore through the cooperation of a multi-stage cyclone separation process, a multi-stage magnetic separation process, a spiral chute, a multi-stage table grading process and a ball mill, so that the recovery rate of the obtained chromium concentrate and chromium middlings is high, the grade of the chromium concentrate is high, the pressure of removing chromium in the wet smelting process of the laterite nickel ore is reduced, the difficulty of subsequent operation is greatly reduced, and the comprehensive utilization of chromium elements is realized; wherein the Cr2O3 grade of the chromium concentrate is greater than or equal to 36%, the recovery rate is greater than or equal to 18%, the Cr2O3 grade of the first chromium middlings is greater than or equal to 15%, the recovery rate is greater than or equal to 30%, the Cr2O3 grade of the second chromium middlings is greater than or equal to 25%, and the chromium content in the high-pressure leaching raw solution is less than or equal to 0.2%.

Description

Technical Field

[0001] The invention belongs to the technical field of ore dressing and relates to a circulating chromium separation process for laterite nickel ore. 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 in laterite nickel ore hydrometallurgy, chromite from laterite nickel ore needs to be beneficiated and impurities removed. Furthermore, this beneficiation and chromium removal process can also yield qualified chromium concentrate, achieving comprehensive resource utilization. Existing technologies for separating chromium from laterite nickel ore typically use single gravity separation or magnetic separation. However, these single separation methods often result in significant chromium loss and result in a low-grade chromium concentrate.

[0004] Therefore, it is necessary to provide a circulating chromium separation process that can improve the grade and recovery rate of chromium concentrate and reduce the chromium content in the subsequent high-pressure leaching solution and the chromium removal pressure. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a circular chromium separation process for laterite nickel ore, which can separate chromium from different mineral phases and improve the grade of chromium concentrate, thereby improving the comprehensive utilization rate of laterite nickel ore.

[0006] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0007] The present invention provides a cyclic chromium selection process, which comprises the following steps:

[0008] (1) washing the laterite nickel ore and performing a cyclone separation in sequence to obtain a cyclone overflow and a cyclone underflow, and then subjecting the cyclone underflow to a first weak magnetic separation and a first strong magnetic separation in sequence to obtain a first chromium middling, a first strong magnetic separation non-magnetic material, and a first strong magnetic separation magnetic material;

[0009] (2) subjecting the first high-intensity magnetic separation magnetic material of step (1) to spiral chute classification, multi-stage shaking table classification, several weak magnetic separations and several spiral classifications in sequence to obtain chromium concentrate, second chromium middlings, weak magnetic separation middlings and mixed light ore;

[0010] (3) mixing the first strong magnetic separation non-magnetic material of step (1) and the mixed light mineral material of step (2), and sequentially subjecting them to first ball milling and second-stage cyclone separation to obtain second-stage cyclone overflow and second-stage cyclone underflow;

[0011] Post-processing the second-stage cyclone overflow and the first-stage cyclone overflow of step (1) to obtain a high-pressure leaching stock solution;

[0012] The second-stage cyclone bottom flow and the ore separated in the weak magnetic separation in step (2) are mixed, subjected to a second ball milling, and then reused in the first strong magnetic separation in step (1).

[0013] In the present invention, the purpose of the mineral processing in step (1) is to remove gravel of different particle size ranges to reduce the interference of gravel in subsequent mineral processing and improve the grade and quality of the concentrate; for example, a drum ore washer can be used to remove gravel with a particle size greater than 35 mm, and then the ore can be processed by a double-helix scrubber and a linear vibrating screen to remove gravel with a particle size greater than 2 mm to obtain a gravel-free ore.

[0014] The circulating chromium separation process provided by the present invention can separate chromite from laterite nickel ore through the coordinated process of multi-stage cyclone separation, multi-stage magnetic separation, spiral chute, multi-stage shaking table classification and ball milling followed by reuse. The obtained chromite concentrate and chromium middlings have a high recovery rate and the grade of the chromite concentrate is high. It is also beneficial to reduce the chromium removal pressure in the wet smelting process of laterite nickel ore, greatly reduce the difficulty of subsequent operations, and realize the comprehensive utilization of the chromium element.

[0015] It is worth noting that the process of first using cyclone separation and then combining weak magnetic and strong magnetic separation fully guarantees the recovery of useful minerals. It also improves the recovery rate of chromium concentrate on the basis of realizing the simple separation of weakly magnetic useful minerals and non-magnetic useful ores, and can screen out more chromium middlings, and significantly reduce the chromium content in the subsequent high-pressure leaching solution, thereby reducing the pressure of chromium removal in the high-pressure leaching solution.

[0016] It is worth noting that the combined process of spiral chute classification, multi-stage shaking table classification, several weak magnetic separations and several spiral classifications can not only obtain chromium concentrate with high Cr2O3 grade, but also further screen out more chromium middlings and separate more light ore.

[0017] It is worth noting that the inventors found that one of the reasons for the low recovery rate and grade of chromite is that the mixed light ore and the first strong magnetic separation non-magnetic material still contain a large amount of chromite embedded in the chromite. Therefore, the present application sequentially performs the first ball milling and the second stage cyclone separation on the mixed light ore and the first strong magnetic separation non-magnetic material, so that the chromite monomer is dissociated in the limonite, and the chromium-containing heavy minerals and light minerals are effectively separated again, further improving the grade of the chromite; then the obtained second stage cyclone bottom flow and the second weak magnetic separation ore are subjected to the second ball milling and reused in the strong magnetic separation process in step (1). The present application improves the monomer dissociation degree of chromite embedded in the limonite through two ball milling treatments, so that the embedded chromite is separated and then subjected to strong magnetic separation again, which is beneficial to the subsequent separation and recovery of chromium, and further improves the recovery rate of chromite concentrate.

[0018] As a preferred technical solution of the present invention, the particle size of the mineral particles in the cyclone bottom flow in step (1) is 74μm to 2mm, for example, it can be 74μm, 100μm, 300μm, 500μm, 800μm, 1mm, 1.2mm, 1.5mm, 1.8mm or 2mm, etc.

[0019] In the present invention, since the grades of Ni and Cr2O3 do not change synchronously with the particle size, most of the chromium-containing impurities can be separated in the first cyclone underflow by controlling the particle size of the ore particles in the underflow of the first cyclone separation within the range of 74 μm to 2 mm, thereby ensuring the full recovery of useful minerals, improving the efficiency and effect of subsequent weak magnetic separation, and further improving the grade of the chromium concentrate.

[0020] Preferably, the first weak magnetic separation in step (1) includes: subjecting a section of cyclone bottom flow to a first weak magnetic separation to obtain a first weak magnetic separation magnetic material and a first weak magnetic separation non-magnetic material.

[0021] Preferably, the first weak magnetic separation magnetic material is subjected to spiral classification to obtain a first chromium middling.

[0022] Preferably, the first weak magnetic separation non-magnetic material is subjected to a first strong magnetic separation.

[0023] As a preferred technical solution of the present invention, the magnetic field strength of the first weak magnetic separation in step (1) is 1200~1800Gs, for example, it can be 1200Gs, 1250Gs, 1300Gs, 1350Gs, 1400Gs, 1450Gs, 1500Gs, 1550Gs, 1600Gs, 1650Gs, 1600Gs, 1700Gs or 1800Gs, etc., preferably 1600~1700Gs.

[0024] Preferably, the magnetic field strength of the first strong magnetic separation in step (1) is 8000-12000 Gs, for example, it can be 8000 Gs, 8500 Gs, 9000 Gs, 9500 Gs, 10000 Gs, 10500 Gs, 11000 Gs, 11500 Gs or 12000 Gs, etc., preferably 10000-11000 Gs.

[0025] It is worth noting that by utilizing the differences in density and magnetic properties between chromite and other chromium-containing mineral phases (such as limonite, spinel, and silicate), a small amount of strongly magnetic chromium-containing minerals can be separated from a section of cyclonic underflow through a first weak magnetic separator at a specific magnetic field strength. This first chromium middlings are recovered and prevented from entering the subsequent strong magnetic separation operation, which would affect the separation efficiency and reduce the grade of the strong magnetic separation concentrate. The first strong magnetic separator, with increased magnetic field strength, then magnetically separates the more strongly magnetic chromium-containing minerals, further improving the grade of the chromium concentrate. By combining weak magnetic separation and strong magnetic separation at specific magnetic field strengths, not only can the recovery rate of chromium concentrate be improved, but more chromium middlings can also be screened out, significantly reducing the chromium content in the subsequent high-pressure leaching solution and reducing the pressure of the high-pressure leaching solution.

[0026] As a preferred technical solution of the present invention, the spiral chute classification in step (2) includes: entering the first strong magnetic separation magnetic material into the spiral chute for classification to obtain chute light ore and chute heavy ore; the chute light ore is one of the components of the mixed light ore.

[0027] In the present invention, the obtained chute heavy ore contains not only valuable metals but also chromium ore phase.

[0028] As a preferred technical solution of the present invention, the multi-stage shaking table classification includes a single-stage shaking table classification and a second-stage shaking table classification performed sequentially.

[0029] Preferably, the one-stage shaking table classification includes: the heavy ore obtained after spiral chute classification is put into the one-stage shaking table for screening to obtain the one-stage shaking table light ore and the one-stage shaking table heavy ore; the one-stage shaking table light ore is one of the components of the mixed light ore.

[0030] Preferably, the two-stage shaking table classification includes: the heavy ore obtained after the first-stage shaking table classification is put into the second-stage shaking table for re-screening to obtain the second-stage shaking table light ore, the second-stage shaking table medium ore and the second-stage shaking table heavy ore; the second-stage shaking table light ore is one of the components of the mixed light ore.

[0031] As a preferred technical solution of the present invention, the several weak magnetic separations in step (2) include a second weak magnetic separation and a third weak magnetic separation which are performed independently.

[0032] Preferably, the magnetic field strength of the second weak magnetic separation is 1250-1500 Gs, for example, it can be 1300 Gs, 1350 Gs, 1400 Gs, 1450 Gs or 1480 Gs.

[0033] In the present invention, a cyclonic underflow is subjected to a second weak magnetic separator under a specific magnetic field strength to separate out strongly magnetic chromium-containing minerals, and high-grade chromium concentrate is obtained after spiral classification.

[0034] Preferably, the magnetic field strength of the third weak magnetic separation is 1000-1200 Gs, for example, it can be 1020 Gs, 1050 Gs, 1080 Gs, 1100 Gs, 1120 Gs, 1150 Gs or 1180 Gs.

[0035] In the present invention, the ore in the second-stage shaking table is further screened by the third weak magnetic separator under a specific magnetic field strength to select chromium-containing minerals with relatively strong magnetism for recovering the second chromium middlings.

[0036] Preferably, the second weak magnetic separation comprises: subjecting the heavy ore obtained after the second-stage shaking table classification to a second weak magnetic separation to obtain a second weak magnetic separation concentrate and a second weak magnetic separation ore.

[0037] Preferably, the second weak magnetic separation concentrate is spirally classified to obtain chromium concentrate.

[0038] Preferably, the third weak magnetic separation comprises: subjecting the middlings obtained after the second-stage shaking table classification to third weak magnetic separation to obtain third weak magnetic separation concentrate and third weak magnetic separation middlings.

[0039] Preferably, the middlings obtained from the second weak magnetic separation are mixed with the concentrate obtained from the third weak magnetic separation, and the mixture is spirally classified to obtain the second chromium middlings.

[0040] As a preferred technical solution of the present invention, in step (3), the output particle size of the mineral particles after the first ball milling is -200 mesh, which accounts for more than 60%.

[0041] It is worth noting that by controlling the particle size range of the first ball mill output, the monomers of chromite encapsulated in limonite are dissociated.

[0042] Preferably, the particle size of the mineral particles in the second-stage cyclone bottom flow in step (3) is 74 to 500 μm, for example, it can be 74 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm or 500 μm.

[0043] In the present invention, by controlling the particle size of the mineral particles in the bottom flow of the second-stage cyclone separation within the range of 74 to 500 μm, most of the chromium-containing impurities can be separated in the bottom flow of the second-stage cyclone separation, thereby ensuring the full recovery of useful minerals.

[0044] As a preferred technical solution of the present invention, the post-treatment in step (3) includes: independently removing impurities from the first-stage cyclone overflow and the second-stage cyclone overflow, and then mixing the impurity-removed solution with a flocculant to perform solid-liquid separation to obtain a high-pressure leaching solution.

[0045] Preferably, in step (3), the mineral particles with a particle size of -200 mesh after the second ball milling account for more than 70%.

[0046] It is worth noting that by controlling the particle size range of the second ball mill output, the monomers of chromite encapsulated in limonite are further dissociated.

[0047] As a preferred technical solution of the present invention, the Cr2O3 content in the first chromium ore in step (1) is ≥15%, for example, it can be 15.2%, 15.5%, 15.8%, 16%, 16.2%, 16.5%, 16.8%, 17%, 17.5%, 18%, 18.5% or 19%, etc.

[0048] Preferably, the recovery rate of the first chromium middling in step (1) is ≥30%, for example, it can be 30.2%, 30.5%, 30.8%, 31%, 31.2%, 31.5%, 31.8% or 32%.

[0049] Preferably, the Cr2O3 content in the second chromium ore in step (2) is ≥25%, for example, it can be 25.2%, 25.5%, 25.8%, 26%, 26.2%, 26.5%, 26.8%, 27%, 27.5%, 28%, 28.5% or 29%, etc.

[0050] Preferably, the Cr2O3 content in the chromium concentrate in step (2) is ≥36%, for example, it can be 36.2%, 36.5%, 36.8%, 37%, 37.2%, 37.5%, 37.8%, 38%, 38.5%, 39%, 39.5% or 40%, etc.

[0051] Preferably, the recovery rate of the chromium concentrate in step (2) is ≥18%, for example, it can be 18.2%, 18.5%, 18.8%, 19%, 19.2%, 19.5%, 19.8%, 20%, 20.5%, 21% or 22%, etc.

[0052] Preferably, the chromium content in the high-pressure leaching solution in step (3) is ≤0.2%, for example, it can be 0.18%, 0.15%, 0.12%, 0.1%, 0.08%, 0.05%, 0.02%, 0.01% or 0.005%, etc., preferably ≤0.05%.

[0053] As a preferred technical solution of the present invention, the cyclic chromium selection process includes the following steps:

[0054] (1) The laterite nickel ore is sequentially subjected to ore washing and a cyclone separation to obtain a cyclone overflow and a cyclone underflow, wherein the particle size of the cyclone underflow is 74 μm to 2 mm; the cyclone underflow is then subjected to a first weak magnetic separation at a magnetic field strength of 1200 to 1800 Gs to obtain a first weak magnetic separation magnetic material and a first weak magnetic separation non-magnetic material, and the first weak magnetic separation magnetic material is then subjected to spiral classification to obtain a first chromium middling with a Cr2O3 content of ≥15% and a recovery rate of ≥30%; and the first weak magnetic separation non-magnetic material is subjected to a first strong magnetic separation at a magnetic field strength of 8000 to 12000 Gs to obtain a first strong magnetic separation non-magnetic material and a first strong magnetic separation magnetic material;

[0055] (2) subjecting the first strong magnetic separation magnetic material of step (1) to spiral chute classification to obtain chute light ore and chute heavy ore, and then subjecting the chute heavy ore to first-stage shaking table classification to obtain first-stage shaking table light ore and first-stage shaking table heavy ore, and then subjecting the first-stage shaking table heavy ore to second-stage shaking table classification to obtain second-stage shaking table light ore, second-stage shaking table medium ore and second-stage shaking table heavy ore;

[0056] The heavy ore material of the second-stage shaking table is subjected to a second weak magnetic separation at a magnetic field strength of 1250-1500 Gs to obtain a second weak magnetic separation concentrate and a second weak magnetic separation ore, and then the second weak magnetic separation concentrate is subjected to spiral classification to obtain a chromium concentrate with a Cr2O3 content of ≥36% and a recovery rate of ≥18%;

[0057] The ore from the second-stage shaking table is subjected to third weak magnetic separation at a magnetic field strength of 1000-1200 Gs to obtain third weak magnetic separation concentrate and third weak magnetic separation middling, and then the middling obtained from the second weak magnetic separation is mixed with the concentrate obtained from the third weak magnetic separation, and after spiral classification, a second chromium middling with a Cr2O3 content of ≥25% is obtained;

[0058] The obtained chute light ore material, the first stage shaking table light ore material and the second stage shaking table light ore material constitute the mixed light ore material;

[0059] (3) mixing the first strong magnetic separation non-magnetic material of step (1) and the mixed light mineral material of step (2), and sequentially subjecting them to first ball milling and second-stage cyclone separation to obtain second-stage cyclone overflow and second-stage cyclone underflow;

[0060] The particle size of the ore particles after the first ball milling is -200 mesh, which accounts for more than 60%; the particle size of the ore particles in the second stage cyclone bottom flow is 74 to 500 μm;

[0061] The second-stage cyclone overflow and the first-stage cyclone overflow of step (1) are subjected to impurity removal respectively and independently, and then the impurity-removed solution is mixed with a flocculant and subjected to solid-liquid separation to obtain a high-pressure leaching stock solution with a chromium content of ≤0.2%;

[0062] The second-stage cyclone bottom flow and the ore separated in the third weak magnetic separation in step (2) are mixed, subjected to a second ball milling, and then reused in the first strong magnetic separation in step (1);

[0063] After the second ball milling, the mineral particles with a particle size of -200 mesh account for more than 70%.

[0064] The numerical range described in the present invention includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0065] Compared with the prior art, the present invention has the following beneficial effects:

[0066] The circulating chromium separation process provided by the present invention can separate chromite from laterite nickel ore through a coordinated process of multi-stage cyclone separation, multi-stage magnetic separation, spiral chute, multi-stage shaking table classification and ball milling followed by reuse. The obtained chromite concentrate and chromite middlings have high recovery rates and the chromite concentrate has high grade. This is also beneficial for reducing the chromium removal pressure during the hydrometallurgical smelting process of laterite nickel ore, greatly reducing the difficulty of subsequent operations, and realizing the comprehensive utilization of the chromium element. The chromite concentrate has a Cr2O3 grade of ≥36% and a recovery rate of ≥18%, the first chromite middlings have a Cr2O3 grade of ≥15% and a recovery rate of ≥30%, the second chromite middlings have a Cr2O3 grade of ≥25%, and the chromium content in the high-pressure leaching stock solution is ≤0.2%. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 This is a flow chart of the circulating chromium separation process for laterite nickel ore provided in Example 1. DETAILED DESCRIPTION

[0068] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0069] The raw materials in the specific embodiment of the present invention are all laterite nickel ore from a tropical rainforest climate island near the equator in Indonesia. The main valuable metal elements of the laterite nickel ore are Ni, Fe and Co, and impurities such as Ca, Mg, Cr2O3 and SiO2 are also present.

[0070] In the following examples and comparative examples, the laterite nickel ore was washed before chromium separation. The washing process was as follows: the raw laterite nickel ore was conveyed by a heavy-duty plate feeder to a drum ore washer to remove gravel with a particle size of 35 mm or greater. The ore was then processed by a double-screw scrubber and a linear vibrating screen to remove gravel with a particle size of 2 mm or greater. The ore was then fed sequentially to a mixing tank and a slurry pump to obtain a de-graveled ore material, which was then assayed for chromium content. The de-graveled ore material had a Cr2O3 grade of 3.21% and a recovery rate of 59.73%.

[0071] Example 1

[0072] This embodiment provides a recycling chromium separation process for laterite nickel ore, the flow chart of which is as follows: Figure 1 As shown, the cyclic chromium selection process includes the following steps:

[0073] (1) The ore material except gravel is introduced into a cyclone for a cyclone separation to obtain a cyclone overflow and a cyclone underflow, wherein the particle size of the cyclone underflow is 74 μm to 2 mm; then the cyclone underflow is subjected to a first weak magnetic separation at a magnetic field strength of 1500 Gs to obtain a first weak magnetic separation magnetic material and a first weak magnetic separation non-magnetic material, and then the first weak magnetic separation magnetic material is collected into a weak magnetic pump pool and spirally classified to obtain a first chromium middling; at the same time, the first weak magnetic separation non-magnetic material is subjected to a first strong magnetic separation at a magnetic field strength of 10000 Gs to obtain a first strong magnetic separation non-magnetic material and a first strong magnetic separation magnetic material;

[0074] (2) The first strong magnetic separation magnetic material of step (1) is collected into a spiral chute for spiral chute classification to obtain chute light ore and chute heavy ore, and then the chute heavy ore is subjected to a first-stage shaking table classification to obtain a first-stage shaking table light ore and a first-stage shaking table heavy ore, and then the first-stage shaking table heavy ore is subjected to a second-stage shaking table classification to obtain a second-stage shaking table light ore, a second-stage shaking table medium ore and a second-stage shaking table heavy ore;

[0075] The heavy ore material in the second-stage shaking table is subjected to a second weak magnetic separation at a magnetic field strength of 1300 Gs to obtain a second weak magnetic separation concentrate and a second weak magnetic separation ore, and then the second weak magnetic separation concentrate is subjected to spiral classification to obtain a chromium concentrate;

[0076] The ore from the second-stage shaking table is subjected to third weak magnetic separation at a magnetic field strength of 1200 Gs to obtain third weak magnetic separation concentrate and third weak magnetic separation middling, and then the middling obtained from the second weak magnetic separation is mixed with the concentrate obtained from the third weak magnetic separation, and spirally classified to obtain the second chromium middling;

[0077] The obtained chute light ore material, the first stage shaking table light ore material and the second stage shaking table light ore material constitute the mixed light ore material;

[0078] (3) mixing the first strong magnetic separation non-magnetic material of step (1) and the mixed light mineral material of step (2), and sequentially subjecting them to first ball milling and second-stage cyclone separation to obtain second-stage cyclone overflow and second-stage cyclone underflow;

[0079] The particle size of the ore particles after the first ball milling is -200 mesh, which accounts for more than 60%; the particle size of the ore particles in the second stage cyclone bottom flow is 74 to 500 μm;

[0080] The overflow of the second-stage cyclone is passed through a second-stage impurity removal screen for second-stage impurity removal and then transported to a raw ore pulp storage tank. At the same time, the overflow of the first-stage cyclone in step (1) is passed through a first-stage impurity removal screen for first-stage impurity removal and then transported to a finished product tank and then to a raw ore pulp storage tank. The mixture in the raw ore pulp storage tank is collected into a thickener containing a flocculant for solid-liquid separation to obtain a high-pressure leaching stock solution.

[0081] The second-stage cyclone bottom flow and the ore separated in the third weak magnetic separation in step (2) are mixed, subjected to a second ball milling, and then reused in the first strong magnetic separation in step (1);

[0082] After the second ball milling, the mineral particles with a particle size of -200 mesh account for more than 70%.

[0083] Example 2

[0084] This embodiment provides a cyclic chromium separation process for laterite nickel ore. This embodiment provides a cyclic chromium separation process for laterite nickel ore, and the cyclic chromium separation process includes the following steps:

[0085] (1) The ore material except gravel is introduced into a cyclone for a cyclone separation to obtain a cyclone overflow and a cyclone underflow, wherein the particle size of the cyclone underflow is 74 μm to 2 mm; then the cyclone underflow is subjected to a first weak magnetic separation at a magnetic field strength of 1300 Gs to obtain a first weak magnetic separation magnetic material and a first weak magnetic separation non-magnetic material, and then the first weak magnetic separation magnetic material is collected into a weak magnetic pump pool and spirally classified to obtain a first chromium middling; at the same time, the first weak magnetic separation non-magnetic material is subjected to a first strong magnetic separation at a magnetic field strength of 11000 Gs to obtain a first strong magnetic separation non-magnetic material and a first strong magnetic separation magnetic material;

[0086] (2) The first strong magnetic separation magnetic material of step (1) is collected into a spiral chute for spiral chute classification to obtain chute light ore and chute heavy ore, and then the chute heavy ore is subjected to a first-stage shaking table classification to obtain a first-stage shaking table light ore and a first-stage shaking table heavy ore, and then the first-stage shaking table heavy ore is subjected to a second-stage shaking table classification to obtain a second-stage shaking table light ore, a second-stage shaking table medium ore and a second-stage shaking table heavy ore;

[0087] The heavy ore material in the second-stage shaking table is subjected to a second weak magnetic separation at a magnetic field strength of 1400Gs to obtain a second weak magnetic separation concentrate and a second weak magnetic separation ore, and then the second weak magnetic separation concentrate is subjected to spiral classification to obtain a chromium concentrate;

[0088] The ore from the second-stage shaking table is subjected to third weak magnetic separation at a magnetic field strength of 1100 Gs to obtain third weak magnetic separation concentrate and third weak magnetic separation middling, and then the middling obtained from the second weak magnetic separation is mixed with the concentrate obtained from the third weak magnetic separation, and spirally classified to obtain the second chromium middling;

[0089] The obtained chute light ore material, the first stage shaking table light ore material and the second stage shaking table light ore material constitute the mixed light ore material;

[0090] (3) mixing the first strong magnetic separation non-magnetic material of step (1) and the mixed light mineral material of step (2), and sequentially subjecting them to first ball milling and second-stage cyclone separation to obtain second-stage cyclone overflow and second-stage cyclone underflow;

[0091] The particle size of the ore particles after the first ball milling is -200 mesh, which accounts for more than 60%; the particle size of the ore particles in the second stage cyclone bottom flow is 74 to 500 μm;

[0092] The overflow of the second-stage cyclone is passed through a second-stage impurity removal screen for second-stage impurity removal and then transported to a raw ore pulp storage tank. At the same time, the overflow of the first-stage cyclone in step (1) is passed through a first-stage impurity removal screen for first-stage impurity removal and then transported to a finished product tank and then to a raw ore pulp storage tank. The mixture in the raw ore pulp storage tank is collected into a thickener containing a flocculant for solid-liquid separation to obtain a high-pressure leaching stock solution.

[0093] The second-stage cyclone bottom flow and the ore separated in the third weak magnetic separation in step (2) are mixed, subjected to a second ball milling, and then reused in the first strong magnetic separation in step (1);

[0094] After the second ball milling, the mineral particles with a particle size of -200 mesh account for more than 70%.

[0095] Example 3

[0096] This embodiment provides a cyclic chromium separation process for laterite nickel ore. Except that the magnetic field intensity of the first weak magnetic separation in step (1) is 800 Gs, other conditions are the same as those in Example 1.

[0097] Example 4

[0098] This embodiment provides a cyclic chromium separation process for laterite nickel ore. Except that the magnetic field intensity of the first weak magnetic separation in step (1) is 2200 Gs, other conditions are the same as those in Example 1.

[0099] Example 5

[0100] This embodiment provides a cyclic chromium separation process for laterite nickel ore. Except that the magnetic field intensity of the first high-intensity magnetic separation in step (1) is 7000 Gs, other conditions are the same as those in Example 1.

[0101] Example 6

[0102] This embodiment provides a cyclic chromium separation process for laterite nickel ore. Except that the magnetic field intensity of the first high-intensity magnetic separation in step (1) is 15000 Gs, other conditions are the same as those in Example 1.

[0103] Example 7

[0104] This embodiment provides a cyclic chromium separation process for laterite nickel ore. Except that the magnetic field intensity of the second weak magnetic separation in step (2) is 800 Gs, other conditions are the same as those in Example 1.

[0105] Example 8

[0106] This embodiment provides a cyclic chromium separation process for laterite nickel ore. Except that the magnetic field intensity of the second weak magnetic separation in step (1) is 2000 Gs, other conditions are the same as those in Example 1.

[0107] Example 9

[0108] This embodiment provides a recycling chromium separation process for laterite nickel ore. Except that the third weak magnetic separation is not performed in step (2), the ore from the second weak magnetic separation and the ore from the second shaking table are both used as the weak magnetic separation ore, and then mixed with the second cyclone underflow, and then reused in the first strong magnetic separation after the second ball milling. Other conditions are the same as those in Example 1.

[0109] Example 10

[0110] This embodiment provides a recycling chromium separation process for laterite nickel ore. Except that in step (3), the ore particles with a particle size of -200 mesh account for more than 40% after the first ball milling, other conditions are the same as those in Example 1.

[0111] Comparative Example 1

[0112] This comparative example provides a cyclic chromium separation process for laterite nickel ore. Except that step (1) does not perform a cyclone separation, other conditions are the same as those in Example 1.

[0113] Comparative Example 2

[0114] This comparative example provides a cyclic chromium separation process for laterite nickel ore. Except that the first weak magnetic separation is not performed in step (1), other conditions are the same as those in Example 1.

[0115] Comparative Example 3

[0116] This comparative example provides a cyclic chromium separation process for laterite nickel ore. Except that the first high-intensity magnetic separation is not performed in step (1), other conditions are the same as those in Example 1.

[0117] Comparative Example 4

[0118] This comparative example provides a cyclic chromium separation process for laterite nickel ore. Except that the first weak magnetic separation and the first high magnetic separation are not performed in step (1), other conditions are the same as those in Example 1.

[0119] Comparative Example 5

[0120] This comparative example provides a recycling chromium separation process for laterite nickel ore. Except that the first weak magnetic separation and the first strong magnetic separation are not performed in step (1), and the ore from the second cyclone underflow and the third weak magnetic separation is not reused after the second ball milling in step (3), other conditions are the same as those in Example 1.

[0121] Comparative Example 6

[0122] This comparative example provides a recycling chromium separation process for laterite nickel ore. Except that in step (3), the ore from the second-stage cyclone underflow and the third weak magnetic separation is not recycled to the first high-intensity magnetic separation after the second ball milling, other conditions are the same as those in Example 1.

[0123] The chromium contents in the chromium concentrate, the first chromium middling, the second chromium middling and the high-pressure leaching solution obtained in the above examples and comparative examples were determined by titration, and the corresponding recoveries were calculated. The specific results are shown in Table 1.

[0124] Table 1

[0125]

[0126] Among them, “ / ” means that the corresponding materials were not obtained.

[0127] From Table 1 we can see that:

[0128] (1) The cyclic chromium separation process provided in Examples 1-2 of the present invention can separate chromite from laterite nickel ore through a coordinated process of multi-stage cyclone separation, multi-stage magnetic separation, spiral chute, multi-stage shaking table classification, and ball milling followed by reuse. The obtained chromite concentrate and chromium middlings have high recovery rates and high grade. The chromium concentrate is also beneficial for reducing the chromium removal pressure during the hydrometallurgical smelting of laterite nickel ore, thereby achieving comprehensive utilization of chromium. The Cr2O3 grade of the chromium concentrate is ≥36%, and the recovery rate is ≥18%. The Cr2O3 grade of the first chromium middlings is ≥15%, and the recovery rate is ≥30%. The Cr2O3 grade of the second chromium middlings is ≥25%, and the chromium content in the high-pressure leaching solution is ≤0.05%.

[0129] (2) From the comparison between Example 1, Examples 3-4 and Comparative Example 2, it can be seen that when the magnetic field intensity of the first weak magnetic separation is low, the chromium ore enters the concentrate tank due to the low magnetic field intensity, which is not conducive to improving the grade of the chromium ore and the chromium concentrate; when the magnetic field intensity of the first weak magnetic separation is high, the chromium concentrate content in the chromium ore is high due to the high magnetic field intensity, which leads to a decrease in the recovery rate of the chromium concentrate; when the first weak magnetic separation is not performed, not only can the first chromium ore not be obtained, but the recovery rate of the chromium concentrate is also reduced, and the chromium content of the obtained high-pressure leaching solution is high;

[0130] (3) From the comparison between Example 1, Examples 5-6, and Comparative Example 3, it can be seen that when the magnetic field intensity of the first high-intensity magnetic separation is low, the chromium middlings enter the concentrate tank due to the low magnetic field intensity, which is not conducive to improving the grade and recovery rate of the chromium concentrate; when the magnetic field intensity of the first high-intensity magnetic separation is high, the recovery rate of the chromium concentrate decreases; when the first high-intensity magnetic separation is not performed, the recovery rate of the chromium concentrate decreases, the grade of the second chromium middlings also decreases, and the chromium content of the obtained high-pressure leaching solution is high;

[0131] (4) From the comparison between Example 1 and Examples 7-8, it can be seen that when the magnetic field intensity of the second weak magnetic separation is not within the preferred range, the grade and recovery rate of the chromium concentrate will also decrease;

[0132] (5) From the comparison between Example 1 and Example 9, it can be seen that if the third weak magnetic separation is not performed, not only can the second chromium ore not be obtained, but the difficulty of the second ball milling is increased, resulting in a higher chromium content in the high-pressure leaching solution;

[0133] (6) From the comparison between Example 1 and Example 10, it can be seen that when the proportion of the ore particles with a particle size of -200 after the first ball milling is too small, the monomers of chromite wrapped in limonite cannot be fully dissociated;

[0134] (7) From the comparison between Example 1 and Comparative Example 1, it can be seen that since a first-stage cyclone separation is not performed, most of the chromium-containing impurities cannot be separated in the first-stage cyclone underflow, and the useful minerals cannot be fully recovered;

[0135] (8) A comprehensive comparison of Example 1 and Comparative Example 6 shows that when the ore from the second-stage cyclone underflow and weak magnetic separation is not recycled to the first high-intensity magnetic separation after ball milling, the grade of the second chromium middlings decreases.

[0136] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A circulating chromium separation process for laterite nickel ore, characterized in that: The cyclic chromium selection process comprises the following steps: (1) The laterite nickel ore is sequentially subjected to ore washing and a first cyclone separation to obtain a first cyclone overflow and a first cyclone underflow, and then the first cyclone underflow is sequentially subjected to a first weak magnetic separation and a first strong magnetic separation to obtain a first chromium middling, a first strong magnetic separation non-magnetic material and a first strong magnetic separation magnetic material; (2) subjecting the first high-intensity magnetic separation magnetic material in step (1) to spiral chute classification, multi-stage shaking table classification, several weak magnetic separations and several spiral classifications in sequence to obtain chromium concentrate, second chromium middlings, weak magnetic separation middlings and mixed light ore; (3) mixing the first strong magnetic separation non-magnetic material of step (1) and the mixed light mineral material of step (2), and sequentially subjecting them to first ball milling and second-stage cyclone separation to obtain second-stage cyclone overflow and second-stage cyclone underflow; Post-processing the overflow of the second-stage cyclone and the overflow of the first-stage cyclone in step (1) to obtain a high-pressure leaching solution; The second-stage cyclone bottom flow and the ore separated in the weak magnetic separation in step (2) are mixed, subjected to a second ball milling, and then reused in the first strong magnetic separation in step (1).

2. The cyclic chromium separation process according to claim 1, characterized in that: The particle size of the ore particles in the cyclone bottom flow in step (1) is 74 μm~2 mm.

3. The cyclic chromium separation process according to claim 1, characterized in that: Step (1) The first weak magnetic separation includes: subjecting a section of cyclone bottom flow to a first weak magnetic separation to obtain a first weak magnetic separation magnetic material and a first weak magnetic separation non-magnetic material.

4. The cyclic chromium separation process according to claim 3, characterized in that: The first weak magnetic separation magnetic material is spirally classified to obtain a first chromium middling.

5. The cyclic chromium separation process according to claim 3, characterized in that: The non-magnetic material obtained by the first weak magnetic separation is subjected to the first strong magnetic separation.

6. The cyclic chromium separation process according to claim 1, characterized in that: The magnetic field strength of the first weak magnetic separation in step (1) is 1200~1800Gs.

7. The cyclic chromium separation process according to claim 6, characterized in that: The magnetic field strength of the first weak magnetic separation in step (1) is 1600~1700Gs.

8. The cyclic chromium separation process according to claim 1, characterized in that: The magnetic field strength of the first strong magnetic separation in step (1) is 8000~12000Gs.

9. The cyclic chromium separation process according to claim 8, characterized in that: The magnetic field strength of the first strong magnetic separation in step (1) is 10000~11000Gs.

10. The cyclic chromium separation process according to claim 1, characterized in that: The spiral chute classification in step (2) includes: feeding the first strong magnetic separation magnetic material into the spiral chute for classification to obtain chute light ore and chute heavy ore; the chute light ore is one of the components of the mixed light ore.

11. The cyclic chromium separation process according to claim 1, characterized in that: The multi-stage shaking table classification includes a first-stage shaking table classification and a second-stage shaking table classification performed sequentially.

12. The cyclic chromium separation process according to claim 11, characterized in that: The first-stage shaking table classification includes: the heavy ore obtained after spiral chute classification is put into the first-stage shaking table for screening to obtain the first-stage shaking table light ore and the first-stage shaking table heavy ore; the first-stage shaking table light ore is one of the components of the mixed light ore.

13. The cyclic chromium separation process according to claim 11, characterized in that: The two-stage shaking table classification includes: the heavy ore obtained after the first-stage shaking table classification is put into the second-stage shaking table for re-screening to obtain the second-stage shaking table light ore, the second-stage shaking table medium ore and the second-stage shaking table heavy ore; the second-stage shaking table light ore is one of the components of the mixed light ore.

14. The cyclic chromium separation process according to claim 1, characterized in that: The several weak magnetic separations in step (2) include a second weak magnetic separation and a third weak magnetic separation which are performed independently.

15. The cyclic chromium separation process according to claim 14, characterized in that: The magnetic field strength of the second weak magnetic separation is 1250~1500Gs.

16. The cyclic chromium separation process according to claim 14, characterized in that: The magnetic field strength of the third weak magnetic separation is 1000~1200Gs.

17. The cyclic chromium separation process according to claim 14, characterized in that: The second weak magnetic separation comprises: subjecting the heavy ore obtained after the second-stage shaking table classification to a second weak magnetic separation to obtain a second weak magnetic separation concentrate and a second weak magnetic separation ore.

18. The cyclic chromium separation process according to claim 17, characterized in that: The second weak magnetic separation concentrate is spirally classified to obtain chromium concentrate.

19. The cyclic chromium separation process according to claim 14, characterized in that: The third weak magnetic separation comprises: performing third weak magnetic separation on the middling material obtained after the second-stage shaking table classification to obtain third weak magnetic separation concentrate and third weak magnetic separation middling.

20. The cyclic chromium separation process according to claim 14, characterized in that: The middlings obtained from the second weak magnetic separation are mixed with the concentrate obtained from the third weak magnetic separation, and the second chromium middlings are obtained after spiral classification.

21. The cyclic chromium separation process according to claim 1, characterized in that: In step (3), the output particle size of the first ball milling is -200 mesh, which accounts for more than 60%.

22. The cyclic chromium separation process according to claim 1, characterized in that: The particle size of the mineral particles in the second-stage cyclone bottom flow in step (3) is 74~500μm.

23. The cyclic chromium separation process according to claim 1, characterized in that: The post-treatment in step (3) includes: removing impurities from the first-stage cyclone overflow and the second-stage cyclone overflow independently, and then mixing the impurity-removed solution with a flocculant to perform solid-liquid separation to obtain a high-pressure leaching stock solution.

24. The cyclic chromium separation process according to claim 1, characterized in that: In step (3), the output particle size of the second ball milling is -200 mesh, accounting for more than 70%.

25. The cyclic chromium separation process according to claim 1, characterized in that: Step (1) The Cr2O3 content in the first chromium ore is ≥15%.

26. The cyclic chromium separation process according to claim 1, characterized in that: The recovery rate of the first chromium middling in step (1) is ≥30%.

27. The cyclic chromium separation process according to claim 1, characterized in that: In step (2), the Cr2O3 content in the second chromium ore is ≥25%.

28. The cyclic chromium separation process according to claim 1, characterized in that: The Cr2O3 content in the chromium concentrate in step (2) is ≥36%.

29. The cyclic chromium separation process according to claim 1, characterized in that: The recovery rate of the chromium concentrate in step (2) is ≥18%.

30. The cyclic chromium separation process according to claim 1, characterized in that: The chromium content in the high-pressure leaching solution in step (3) is ≤0.2%.

31. The cyclic chromium separation process according to claim 30, characterized in that: The chromium content in the high-pressure leaching solution in step (3) is ≤0.05%.

32. The cyclic chromium separation process according to claim 1, characterized in that: The cyclic chromium selection process comprises the following steps: (1) The laterite nickel ore is sequentially subjected to ore washing and a cyclone separation to obtain a cyclone overflow and a cyclone underflow, wherein the particle size of the cyclone underflow is 74 μm to 2 mm; the cyclone underflow is then subjected to a first weak magnetic separation at a magnetic field strength of 1200 to 1800 Gs to obtain a first weak magnetic separation magnetic material and a first weak magnetic separation non-magnetic material, and the first weak magnetic separation magnetic material is then subjected to spiral classification to obtain a first chromium middling with a Cr2O3 content of ≥15% and a recovery rate of ≥30%; at the same time, the first weak magnetic separation non-magnetic material is subjected to a first strong magnetic separation at a magnetic field strength of 8000 to 12000 Gs to obtain a first strong magnetic separation non-magnetic material and a first strong magnetic separation magnetic material; (2) The first strong magnetic separation magnetic material of step (1) is subjected to spiral chute classification to obtain chute light ore and chute heavy ore, and then the chute heavy ore is subjected to a first-stage shaking table classification to obtain a first-stage shaking table light ore and a first-stage shaking table heavy ore, and then the first-stage shaking table heavy ore is subjected to a second-stage shaking table classification to obtain a second-stage shaking table light ore, a second-stage shaking table medium ore and a second-stage shaking table heavy ore; The heavy ore material in the second-stage shaking table is subjected to a second weak magnetic separation at a magnetic field strength of 1250-1500 Gs to obtain a second weak magnetic separation concentrate and a second weak magnetic separation ore, and then the second weak magnetic separation concentrate is subjected to spiral classification to obtain a chromium concentrate with a Cr2O3 content of ≥36% and a recovery rate of ≥18%; The ore from the second-stage shaking table is subjected to third weak magnetic separation at a magnetic field strength of 1000-1200 Gs to obtain third weak magnetic separation concentrate and third weak magnetic separation middling, and then the middling obtained from the second weak magnetic separation is mixed with the concentrate obtained from the third weak magnetic separation, and after spiral classification, a second chromium middling with a Cr2O3 content of ≥25% is obtained; The obtained chute light ore material, the first stage shaking table light ore material and the second stage shaking table light ore material constitute the mixed light ore material; (3) mixing the first strong magnetic separation non-magnetic material of step (1) and the mixed light mineral material of step (2), and sequentially subjecting them to first ball milling and second-stage cyclone separation to obtain second-stage cyclone overflow and second-stage cyclone underflow; The output particle size of the first ball mill is -200 mesh mineral particles, which accounts for more than 60%; the particle size of the mineral particles in the second stage cyclone bottom flow is 74-500 μm; The second-stage cyclone overflow and the first-stage cyclone overflow of step (1) are subjected to impurity removal respectively and independently, and then the impurity-removed solution is mixed with a flocculant and solid-liquid separation is performed to obtain a high-pressure leaching stock solution with a chromium content of ≤0.2%; The second-stage cyclone bottom flow and the ore separated in the third weak magnetic separation in step (2) are mixed, subjected to a second ball milling, and then reused in the first strong magnetic separation in step (1); After the second ball milling, the mineral particles with a particle size of -200 mesh account for more than 70%.

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