Circulating chromium separation process for laterite-nickel ore

Abstract

According to the circular chromium separation process for the laterite-nickel ore, through the matched process of multi-stage cyclone separation, multi-stage magnetic separation, the spiral chute, multi-stage table classification and reutilization after ball milling, chromite in the laterite-nickel ore can be separated, the recovery rate of the obtained chromium concentrate and chromium middling is high, the grade of the chromium concentrate is high, and the chromium concentrate can be recycled. The chromium removal pressure in the laterite-nickel ore hydrometallurgy process is reduced, the follow-up operation difficulty is greatly reduced, and comprehensive utilization of the chromium element is achieved; wherein the Cr2O3 grade of the chromium concentrate is larger than or equal to 36%, the recovery rate is larger than or equal to 18%, the Cr2O3 grade of the first chromium middling is larger than or equal to 15%, the recovery rate is larger than or equal to 30%, the Cr2O3 grade of the second chromium middling is larger than or equal to 25%, and the chromium content in the high-pressure leaching stock solution is smaller 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 dressing process for laterite nickel ore. Background Art

[0002] At present, the hydrometallurgy of laterite nickel ore through high-pressure acid leaching has a very broad prospect in the new energy industry. However, high-pressure acid leaching requires expensive corrosion-resistant equipment. The associated spinel-type chromite in laterite nickel ore has a strong abrasive effect on the anti-corrosion layer of the hydrometallurgy equipment, which not only increases the equipment cost of laterite nickel ore hydrometallurgy but also poses a safety risk. At the same time, after high-pressure acid leaching, it is also necessary to remove impurities such as iron, aluminum, and chromium to ensure the grade of the product after the hydrometallurgy of laterite nickel ore.

[0003] In order to reduce the negative impact of chromite in the hydrometallurgical smelting of laterite nickel ore, it is necessary to beneficiate and remove impurities from the chromite in the laterite nickel ore; at the same time, some qualified chromium concentrate can be obtained in the beneficiation and chromium removal steps to achieve comprehensive resource utilization. For the separation of chromium in laterite nickel ore, the existing technology generally adopts a single gravity separation or magnetic separation method, and a single separation method often loses a large part of chromium, and the grade of the obtained chromium concentrate is also low.

[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 and chromium removal pressure in the subsequent high-pressure leaching solution. Summary of the invention

[0005] In view of the shortcomings of the prior art, the object of the present invention is to provide a circulating chromium selection 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 first cyclone separation in sequence to obtain a first cyclone overflow and a first cyclone underflow, and then performing a first weak magnetic separation and a first strong magnetic separation on the first cyclone underflow 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 strong 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;

[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 the mixture to first ball milling and second-stage cyclone separation to obtain second-stage cyclone overflow and second-stage cyclone underflow;

[0011] Post-treating 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 underflow and the ore from the weak magnetic separation in step (2) are mixed, subjected to a second ball mill, 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, so as 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 a double-helix scrubber and a linear vibrating screen can be used 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 the chromite in the laterite nickel ore through the coordinated processes of multi-stage cyclone separation, multi-stage magnetic separation, spiral chute, multi-stage shaking table classification and ball milling and then reuse, and the recovery rate of the obtained chromium concentrate and chromium middlings is high, and the grade of the chromium concentrate is high. It is also beneficial to reduce the chromium removal pressure in the laterite nickel ore wet smelting process, greatly reduce the difficulty of subsequent operations, and realize the comprehensive utilization of the chromium element.

[0015] It is worth mentioning 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 mentioning 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, further screen out more chromium middlings, but also separate more light ore.

[0017] It is worth mentioning 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, thereby further improving the grade of the chromite; subsequently, the obtained second stage cyclone bottom flow and the second weak magnetic separation ore are subjected to the second ball milling and then reused in the strong magnetic separation process in step (1). The present application improves the monomer dissociation degree of chromite embedded in 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, thereby further improving the recovery rate of chromium concentrate.

[0018] As a preferred technical solution of the present invention, the particle size of the ore 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 underflow of a cyclone separation by controlling the particle size of the ore particles in the underflow of a cyclone separation within the range of 74μm to 2mm, 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) comprises: subjecting a section of cyclone underflow 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 1200-1800 Gs, for example, it can be 1200 Gs, 1250 Gs, 1300 Gs, 1350 Gs, 1400 Gs, 1450 Gs, 1500 Gs, 1550 Gs, 1600 Gs, 1650 Gs, 1600 Gs, 1700 Gs or 1800 Gs, etc., preferably 1600-1700 Gs.

[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 ore phases (such as limonite, spinel, and silicate), a small amount of strongly magnetic chromium-containing minerals can be separated from a section of cyclonic bottom flow through the first weak magnetic separator at a specific magnetic field strength, and the first chromium middlings are first recovered to prevent them from entering the subsequent strong magnetic separation operation, affecting the separation efficiency and reducing the grade of the strong magnetic separation concentrate. Then, the first strong magnetic separator with increased magnetic field strength is used to magnetically separate the chromium-containing minerals with stronger magnetism, further improving the grade of the chromium concentrate. By combining weak magnetic separation and strong magnetic separation at a specific magnetic field strength, not only can the recovery rate of chromium concentrate be improved, but more chromium middlings can also be screened out, so that the chromium content in the subsequent high-pressure leaching stock solution is significantly reduced, and the pressure of the high-pressure leaching stock solution is reduced.

[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 a one-stage shaking table light ore and a 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 section of cyclone bottom flow can be separated into strongly magnetic chromium-containing minerals by a second weak magnetic separator under a specific magnetic field strength, and high-grade chromium concentrate can be 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 material in the second-stage shaking table is continuously 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 middling material obtained after the second-stage shaking table classification to the third weak magnetic separation to obtain the third weak magnetic separation concentrate and the third weak magnetic separation middling.

[0039] Preferably, the middlings obtained from the second weak magnetic separation are mixed with the concentrates obtained from the third weak magnetic separation, and the second chromium middlings are obtained after spiral classification.

[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 monomer dissociation of chromite encapsulated in limonite is achieved.

[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, etc.

[0043] In the present invention, by controlling the particle size of the ore 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 stock 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, in step (1), the Cr2O3 content in the first chromium ore 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 ore 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 of 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 comprises the following steps:

[0054] (1) washing the laterite nickel ore and performing a cyclone separation in sequence to obtain a cyclone overflow and a cyclone underflow, wherein the ore particle size of the cyclone underflow is 74 μm to 2 mm; then performing a first weak magnetic separation on the cyclone underflow 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 then performing spiral classification on the first weak magnetic separation magnetic material to obtain a first chromium medium ore with a Cr2O3 content of ≥15% and a recovery rate of ≥30%; and at the same time, performing a first strong magnetic separation on the first weak magnetic separation non-magnetic material 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 in 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 by the second weak magnetic separation is mixed with the concentrate obtained by 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 the mixture 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 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 to perform solid-liquid separation to obtain a high-pressure leaching stock solution with a chromium content of ≤0.2%;

[0062] The second-stage cyclone underflow and the ore separated in the third weak magnetic separation in step (2) are mixed, subjected to a second ball mill, 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 not only includes the point values ​​listed above, but also includes 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 selection process provided by the present invention can separate the chromite in the laterite nickel ore through the coordinated processes of multi-stage cyclone separation, multi-stage magnetic separation, spiral chute, multi-stage shaking table classification and ball milling and then reuse, and the obtained chromite concentrate and chromite middlings have high recovery rates, and the chromite concentrate has high grade, which is also beneficial to reducing the chromium removal pressure in the laterite nickel ore wet smelting process, greatly reducing the difficulty of subsequent operations, and realizing the comprehensive utilization of chromium elements; wherein, the Cr2O3 grade of the chromite concentrate is ≥36% and the recovery rate is ≥18%, the Cr2O3 grade of the first chromite middlings is ≥15% and the recovery rate is ≥30%, the Cr2O3 grade of the second chromite middlings is ≥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 cyclic chromium selection process of laterite nickel ore provided in Example 1. DETAILED DESCRIPTION

[0068] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only 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 implementation mode of the present invention are all laterite nickel ore on a tropical rainforest climate island near the equator in Indonesia. The laterite nickel ore mainly contains valuable metal elements such as Ni, Fe and Co, and also contains impurities such as Ca, Mg, Cr2O3 and SiO2.

[0070] In the following embodiments and comparative examples, the laterite nickel ore was washed before chromium selection, and the washing was carried out by the following method: the laterite nickel ore was transported to the drum washing machine by a heavy plate feeder to remove gravel with a particle size of ≥35 mm, and then the double spiral scrubber and linear vibrating screen were used to remove gravel with a particle size of ≥2 mm, and then the gravel was successively input into the mixing tank and the slurry pump to obtain the gravel-free ore, and the content of the gravel-free ore was measured. The Cr2O3 grade in the gravel-free ore was 3.21%, and the recovery rate was 59.73%.

[0071] Example 1

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

[0073] (1) introducing the ore material except gravel 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 subjecting the cyclone underflow 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 collecting the first weak magnetic separation magnetic material into a weak magnetic pump pool for spiral classification to obtain a first chromium middling; at the same time, subjecting the first weak magnetic separation non-magnetic material 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 introduced into a spiral chute for spiral chute classification to obtain chute light ore and chute heavy ore, and then the chute heavy ore is classified on a first-stage shaking table 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 classified on a second-stage shaking table 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 of the second-stage shaking table is subjected to second weak magnetic separation at a magnetic field strength of 1300 Gs to obtain second weak magnetic separation concentrate and second weak magnetic separation ore, and then the second weak magnetic separation concentrate is subjected to spiral classification to obtain chromium concentrate;

[0076] The ore in 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 the second chromium middling is obtained after spiral classification;

[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 the mixture 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 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 transported to the raw ore slurry storage tank after being removed by the second-stage impurity removal screen. At the same time, the overflow of the first-stage cyclone in step (1) is first transported to the finished product tank and then to the raw ore slurry storage tank after being removed by the first-stage impurity removal screen. 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.

[0081] The second-stage cyclone underflow and the ore separated in the third weak magnetic separation in step (2) are mixed, subjected to a second ball mill, 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] The present embodiment provides a cyclic chromium separation process for laterite nickel ore. The present embodiment provides a cyclic chromium separation process for laterite nickel ore, and the cyclic chromium separation process comprises the following steps:

[0085] (1) introducing the ore except gravel 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 subjecting the cyclone underflow 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 collecting the first weak magnetic separation magnetic material into a weak magnetic pump pool for spiral classification to obtain a first chromium middling; at the same time, subjecting the first weak magnetic separation non-magnetic material 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 introduced into a spiral chute for spiral chute classification to obtain chute light ore and chute heavy ore, and then the chute heavy ore is classified on a first-stage shaking table 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 classified on a second-stage shaking table 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 of the second-stage shaking table is subjected to second weak magnetic separation at a magnetic field strength of 1400 Gs to obtain second weak magnetic separation concentrate and second weak magnetic separation ore, and then the second weak magnetic separation concentrate is subjected to spiral classification to obtain chromium concentrate;

[0088] The ore in 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 by the second weak magnetic separation is mixed with the concentrate obtained by the third weak magnetic separation, and the second chromium middling is obtained after spiral classification;

[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 the mixture 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 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 transported to the raw ore slurry storage tank after being removed by the second-stage impurity removal screen. At the same time, the overflow of the first-stage cyclone in step (1) is first transported to the finished product tank and then to the raw ore slurry storage tank after being removed by the first-stage impurity removal screen. 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.

[0093] The second-stage cyclone underflow and the ore separated in the third weak magnetic separation in step (2) are mixed, subjected to a second ball mill, 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 embodiment 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] The present embodiment provides a recycling chromium separation process for laterite nickel ore, except that the third weak magnetic separation is not performed in step (2), that is, the ore from the second weak magnetic separation and the ore from the second shaking table are both used as the ore from the weak magnetic separation, and then mixed with the second cyclone underflow, and reused in the first strong magnetic separation after the second ball milling, and 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 after the first ball milling account for more than 40%, other conditions are the same as those in embodiment 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 strong 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 recycled after the second ball milling in step (3), the 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 second-stage cyclone underflow and the ore from the third weak magnetic separation are not recycled to the first strong magnetic separation after the second ball milling, the 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 stock solution obtained in the above embodiments and comparative examples were determined by titration, and the corresponding recovery rates were calculated. The specific results are shown in Table 1.

[0124] Table 1

[0125]

[0126] Among them, “ / ” means that the corresponding material was 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 and then reuse, and the obtained chromium concentrate and chromium middlings have high recovery rates and high grade of chromium concentrate, which is also beneficial to reducing the chromium removal pressure in the hydrometallurgical process of laterite nickel ore, thereby realizing the comprehensive utilization of chromium element; wherein, 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 stock solution is ≤0.05%;

[0129] (2) By comparing Example 1 with 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 also the recovery rate of the chromium concentrate is reduced, and the chromium content of the obtained high-pressure leaching solution is high;

[0130] (3) By comparing Example 1 with Examples 5-6 and Comparative Example 3, it can be seen that when the magnetic field strength of the first high-intensity magnetic separation is low, the chromium ore enters the concentrate tank due to the low magnetic field strength, which is not conducive to improving the grade and recovery rate of the chromium concentrate; when the magnetic field strength 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 ore also decreases, and the chromium content of the obtained high-pressure leaching solution is high;

[0131] (4) By comparing Example 1 with 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 chrome concentrate will also decrease;

[0132] (5) It can be seen from the comparison between Example 1 and Example 9 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 transported 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 ore encapsulated in limonite cannot be fully dissociated;

[0134] (7) By comparing Example 1 with 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 a first-stage cyclone underflow, and the useful minerals cannot be fully recovered;

[0135] (8) By comparing Example 1 with Comparative Example 6, it can be seen that when the ore from the second-stage cyclone underflow and the weak magnetic separation is not recycled to the first strong magnetic separation after ball milling, the grade of the second chromium ore decreases.

[0136] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope 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 shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A cyclic chromium separation process for laterite nickel ore, characterized in that: The cyclic chromium selection process comprises the following steps: (1) washing the laterite nickel ore and performing a first cyclone separation in sequence to obtain a first cyclone overflow and a first cyclone underflow, and then performing a first weak magnetic separation and a first strong magnetic separation on the first cyclone underflow in sequence 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 strong 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 the mixture to first ball milling and second-stage cyclone separation to obtain second-stage cyclone overflow and second-stage cyclone underflow; Post-treating the second-stage cyclone overflow and the first-stage cyclone overflow of step (1) to obtain a high-pressure leaching stock solution; The second-stage cyclone underflow and the ore from the weak magnetic separation in step (2) are mixed, subjected to a second ball mill, and then reused in the first strong magnetic separation in step (1).

2. The cyclic chromium selection 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 to 2 mm; Preferably, the first weak magnetic separation in step (1) comprises: subjecting a section of cyclone underflow to a first weak magnetic separation to obtain a first weak magnetic separation magnetic material and a first weak magnetic separation non-magnetic material; Preferably, the first weak magnetic separation magnetic material is subjected to spiral classification to obtain a first chromium middling; Preferably, the first weak magnetic separation non-magnetic material is subjected to a first strong magnetic separation.

3. The cyclic chromium selection process according to claim 1 or 2, characterized in that: Step (1) The magnetic field strength of the first weak magnetic separation is 1200 to 1800 Gs, preferably 1600 to 1700 Gs; Preferably, the magnetic field strength of the first strong magnetic separation in step (1) is 8000-12000 Gs, preferably 10000-11000 Gs.

4. The cyclic chromium separation process according to any one of claims 1 to 3, 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.

5. The cyclic chromium separation process according to any one of claims 1 to 4, 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; Preferably, the one-stage shaking table classification comprises: 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; 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.

6. The cyclic chromium separation process according to any one of claims 1 to 5, characterized in that: The plurality of weak magnetic separations in step (2) include a second weak magnetic separation and a third weak magnetic separation which are performed independently; Preferably, the magnetic field strength of the second weak magnetic separation is 1250-1500 Gs; Preferably, the magnetic field strength of the third weak magnetic separation is 1000-1200 Gs; 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; Preferably, the second weak magnetic separation concentrate is subjected to spiral classification to obtain chromium concentrate; Preferably, the third weak magnetic separation comprises: subjecting the middling material obtained after the second-stage shaking table classification to the third weak magnetic separation to obtain the third weak magnetic separation concentrate and the third weak magnetic separation ore; Preferably, the middlings obtained from the second weak magnetic separation are mixed with the concentrates obtained from the third weak magnetic separation, and the second chromium middlings are obtained after spiral classification.

7. The cyclic chromium separation process according to any one of claims 1 to 6, characterized in that: Step (3) after the first ball milling, the mineral particles with a particle size of -200 mesh account for more than 60%; Preferably, the particle size of the mineral particles in the second-stage cyclone bottom flow in step (3) is 74 to 500 μm.

8. The cyclic chromium separation process according to any one of claims 1 to 7, characterized in that: The post-treatment in step (3) comprises: removing impurities from the first-stage cyclone overflow and the second-stage cyclone overflow respectively, and then mixing the solution after the impurities removal with a flocculant, performing solid-liquid separation, and obtaining a high-pressure leaching stock solution; Preferably, in step (3), the mineral particles with a particle size of -200 mesh after the second ball milling account for more than 70%.

9. The cyclic chromium separation process according to any one of claims 1 to 8, characterized in that: Step (1) the Cr2O3 content in the first chromium ore is ≥ 15%; Preferably, the recovery rate of the first chromium ore in step (1) is ≥30%; Preferably, in step (2), the Cr2O3 content in the second chromium ore is ≥ 25%; Preferably, the Cr2O3 content in the chromium concentrate in step (2) is ≥36%; Preferably, the recovery rate of the chromium concentrate in step (2) is ≥18%; Preferably, the chromium content in the high-pressure leaching solution in step (3) is ≤0.2%, preferably ≤0.05%.

10. The cyclic chromium separation process according to any one of claims 1 to 9, characterized in that: The cyclic chromium selection process comprises the following steps: (1) washing the laterite nickel ore and performing a cyclone separation in sequence to obtain a cyclone overflow and a cyclone underflow, wherein the ore particle size of the cyclone underflow is 74 μm to 2 mm; then performing a first weak magnetic separation on the cyclone underflow 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 then performing spiral classification on the first weak magnetic separation magnetic material to obtain a first chromium medium ore with a Cr2O3 content of ≥15% and a recovery rate of ≥30%; and at the same time, performing a first strong magnetic separation on the first weak magnetic separation non-magnetic material 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) 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; 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%; The ore in 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 by the second weak magnetic separation is mixed with the concentrate obtained by 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 the mixture to first ball milling and second-stage cyclone separation to obtain second-stage cyclone overflow and second-stage cyclone underflow; The particle size of the ore particles after the first ball milling is -200 mesh accounts for more than 60%; the particle size of the ore 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 to perform solid-liquid separation to obtain a high-pressure leaching stock solution with a chromium content of ≤0.2%; The second-stage cyclone underflow and the ore separated in the third weak magnetic separation in step (2) are mixed, subjected to a second ball mill, 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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