Low-grade iron lepidolite ore flotation pre-concentration-magnetic separation upgrading method

Abstract

The present application relates to a kind of low-grade iron lepidolite ore flotation pre-concentration-magnetic separation upgrading method, belong to mineral processing technical field.The present application carries out coarse grinding, slurry conditioning to low-grade iron lepidolite ore, under the synergistic effect of combined reagent and flotation column, using two times flotation column roughing, can efficiently recover iron lepidolite in ore, then the lithium rough concentrate obtained by flotation is defoamed, and is finely ground, and it is enriched again by high gradient magnetic separation, i.e. high-quality lithium concentrate can be obtained.The flotation pre-concentration process used in the present application only includes two roughing operations, no cleaning and scavenging operations, and does not involve middlings return, which can avoid the circulation of slime in the flotation system, and using flotation column as a separation device can improve the pre-concentration effect of micro-fine particle grade iron lepidolite, greatly reducing the ore processing capacity and energy consumption of subsequent process;Using high gradient magnetic separation can effectively separate iron lepidolite ore and gangue minerals such as muscovite, which is fully dissociated by fine grinding process, to realize lithium concentrate upgrading and impurity reduction.

Description

Technical Field

[0001] This invention relates to a flotation pre-enrichment-magnetic separation upgrading method for low-grade lithium iron ore, belonging to the field of mineral processing technology. Background Technology

[0002] Lithium iron ore is an important lithium extraction raw material, often associated with gangue minerals such as muscovite, feldspar, quartz, and calcium carbonate. It is characterized by low lithium content, high impurity content, and complex intergrowth relationships. In particular, the muscovite minerals associated with the ore have essentially the same crystal lattice and surface properties as lithium iron ore, and their action mechanism is extremely similar to that of flotation reagents. It is difficult to effectively separate them using a single flotation process, resulting in poor quality lithium concentrate and difficulties in market sales.

[0003] Due to the increasing weathering and severe mudification of lepidolite beds, their mineralogical properties are complex. In production, the separation process is typically controlled by adding flotation steps or large amounts of reagents, but this results in a long flotation process, numerous reagent addition points, high investment, and complex operation. Furthermore, the large amount of slime present in lepidolite ore affects reagent selectivity, mineralization rate, froth viscosity, middlings circulation, and pulp rheological properties. The presence of slime also increases the stability and viscosity of the froth generated in the flotation machine, resulting in a thick, poorly fluid froth layer. The surge in froth volume leads to severe "cell runoff." Simultaneously, the continuous accumulation of slime in the conventional flotation process worsens the separation effect of lepidolite, making the flotation process difficult to operate.

[0004] Therefore, it is urgent to develop new process flows and equipment that match the properties of low-grade lithium iron ore, and at the same time, to develop green and efficient flotation reagents to target and regulate the solid-liquid interface, slurry environment, and foam characteristics, so as to economically and efficiently recover low-grade lithium iron ore resources and provide technical support for the green, low-carbon and efficient utilization of complex and difficult-to-process lithium ores. Summary of the Invention

[0005] To address the technical challenges of traditional processes for low-grade lepidolite mica ore, such as long process flow, numerous reagent addition points, significant impact from middlings return, unstable production, and poor recovery indicators, this invention provides a flotation pre-enrichment-magnetic separation method for upgrading low-grade lepidolite mica ore. This method involves developing a combination of modifiers to selectively inhibit gangue minerals and precisely controlling the slurry environment, as well as developing a combination of collectors to target and hydrophobize lepidolite mica in the ore. Then, a flotation column is used to pre-enrich the low-grade lepidolite mica ore, removing most of the gangue and reducing the ore throughput in subsequent processes. The resulting lithium concentrate is defoamed and then finely ground to fully liberate the lepidolite mica. High-gradient magnetic separation is then used to further enrich the lithium concentrate, effectively separating the lepidolite mica ore from gangue minerals such as muscovite, thus upgrading and reducing impurities in the lithium concentrate.

[0006] A flotation pre-enrichment-magnetic separation upgrading method for low-grade lithium iron ore, the specific steps of which are as follows:

[0007] (1) The low-grade lithium mica ore is crushed and coarsely ground, and then water is added to adjust the slurry mass percentage concentration to 28-40%;

[0008] (2) Add combined modifier and combined collector to the slurry obtained in step (1) in sequence, and carry out a first flotation column roughing operation in the flotation column to obtain the first flotation column roughing concentrate and the first flotation column roughing tailings;

[0009] (3) Add a combination modifier and a combination collector to the primary flotation column roughing tailings obtained in step (2) and perform secondary flotation column roughing operation in the flotation column to obtain secondary flotation column roughing concentrate and secondary flotation column roughing tailings; the secondary flotation column roughing tailings are flotation tailings.

[0010] (4) Combine the primary flotation column rougher concentrate obtained in step (2) and the secondary flotation column rougher concentrate obtained in step (3) to obtain coarse-grained lithium rougher concentrate. After slurry preparation, defoaming and fine grinding are performed, and water is added to adjust the slurry mass percentage concentration to 10~20%.

[0011] (5) The slurry obtained in step (4) is subjected to a high gradient magnetic separator for a first magnetic separation operation to obtain a first magnetic concentrate and a first magnetic tailings;

[0012] (6) The tailings obtained from the primary magnetic separation in step (5) are subjected to secondary magnetic separation by a high-gradient magnetic separator to obtain secondary magnetic concentrate and secondary magnetic tailings; the secondary magnetic tailings are magnetic tailings.

[0013] (7) Combine the primary magnetic separation concentrate obtained in step (5) and the secondary magnetic separation concentrate obtained in step (6) to obtain a magnetic separation mixed concentrate, which is lithium concentrate;

[0014] The combined modifier is a mixture of sodium carbonate and sodium hexametaphosphate, and the combined collector is a mixture of dodecylamine acetate, sodium cocoyl sulfate, di(hydroxyethyl)methyldodecyl ammonium chloride, and ethoxylated alkyl sulfate.

[0015] Preferably, the mass percentage of Li2O in the low-grade lithium iron ore in step (1) is 0.29~0.63%.

[0016] Preferably, for every ton of low-grade lithium iron ore, 400-600g of combined modifier and 380-540g of combined collector are added to the slurry in the roughing operation of the first flotation column in step (2).

[0017] Preferably, for every ton of low-grade lithium iron ore, 200-300g of combined modifier and 190-270g of combined collector are added to the slurry in the roughing operation of the secondary flotation column in step (3).

[0018] Preferably, based on a mass fraction of 100% for the composite modifier, sodium carbonate accounts for 45-65% and sodium hexametaphosphate accounts for 35-55%.

[0019] Preferably, based on a mass fraction of 100% for the composite collector, the composite collector contains 35-45% dodecylamine acetate, 30-40% sodium cocoyl sulfate, 5-15% di(hydroxyethyl)methyldodecyl ammonium chloride, and 10-20% sodium ethoxylated alkyl sulfate.

[0020] Preferably, the magnetic field strength of the first magnetic separation operation in step (5) is 1.5~1.7T.

[0021] Preferably, the magnetic field strength of the secondary magnetic separation operation in step (6) is 1.6~1.8T.

[0022] The beneficial effects of this invention are:

[0023] (1) This invention is based on a combined flotation-magnetic separation secondary enrichment process. It adopts segmented grinding to optimize the particle size distribution, pre-enriches low-grade lithium iron ore through a flotation column, and then finely grinds the lithium rough concentrate obtained by flotation after defoaming treatment to fully liberate the lithium iron ore. High-gradient magnetic separation is used to further enrich the lithium rough concentrate, thereby promoting the effective separation of lithium iron ore from gangue minerals such as muscovite, and achieving the improvement of lithium concentrate quality and reduction of impurities.

[0024] (2) The combined modifier developed in this invention can not only selectively inhibit gangue minerals, but also precisely regulate the slurry environment. The combined collector can target and hydrophobically react with lithium mica in the ore. Only two flotation column roughing processes are needed to efficiently recover lithium mica from the ore, giving full play to the synergistic effect of the flotation column and the reagent, removing most of the gangue, and greatly reducing the amount of ore to be processed in subsequent processes.

[0025] (3) The flotation pre-enrichment process of the present invention only includes two roughing operations, without cleaning and scavenging operations, and does not involve middlings return, thus avoiding the accumulation and circulation of slime in the flotation system, eliminating the deterioration of flotation indicators by slime, and using flotation columns as separation equipment to extend the bubble residence time, promote the stable adhesion of fine-grained lithium iron phosphate mica to bubbles, optimize the flotation foam structure and ore carrying capacity, and improve the flotation effect;

[0026] (4) The present invention adopts flotation pre-enrichment process to improve the grade of magnetic separation feed while greatly reducing the amount of ore processed in fine grinding process. It can reduce the number of magnetic separation, dewatering and other equipment and energy consumption. High-quality lithium concentrate can be obtained by using secondary magnetic separation operation. The short process can realize the efficient recovery of all-grade lithium iron ore mica. It economically and efficiently solves the technical problems of long process, many reagent addition points, large impact of middlings return, unstable production process and poor recovery index of low-grade lithium iron ore mica ore using traditional process. Attached Figure Description

[0027] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0029] In this embodiment of the invention, the combined modifier is a mixture of sodium carbonate and sodium hexametaphosphate, and the combined collector is a mixture of dodecylamine acetate, sodium cocoyl sulfate, di(hydroxyethyl)methyldodecyl ammonium chloride and ethoxylated alkyl sulfate.

[0030] Example 1: In this example, based on a mass fraction of 100% for the composite modifier, sodium carbonate accounts for 45% and sodium hexametaphosphate accounts for 55%; based on a mass fraction of 100% for the composite collector, dodecylamine acetate accounts for 35%, sodium cocoyl sulfate accounts for 40%, di(hydroxyethyl)methyldodecyl ammonium chloride accounts for 15%, and ethoxylated alkyl sulfate accounts for 10%.

[0031] like Figure 1 As shown, a flotation pre-enrichment-magnetic separation upgrading method for low-grade lithium iron ore is described, with the following specific steps:

[0032] (1) The low-grade lithium iron ore is crushed and coarsely ground, and then water is added to adjust the mass percentage concentration of the slurry to 28%; wherein the mass percentage content of Li2O in the low-grade lithium iron ore is 0.29%;

[0033] (2) Add the combined modifier and the combined collector to the slurry obtained in step (1) in sequence, and carry out a first flotation column roughing operation in the flotation column to obtain the first flotation column roughing concentrate and the first flotation column roughing tailings; 400g of combined modifier and 380g of combined collector are added to the slurry of the first flotation column roughing operation per ton of low-grade lithium iron ore.

[0034] (3) Add a combination modifier and a combination collector to the roughing tailings obtained in step (2) and perform a second flotation column roughing operation in the flotation column to obtain a second flotation column roughing concentrate and a second flotation column roughing tailings; the second flotation column roughing tailings are flotation tailings; based on each ton of low-grade lithium iron ore, add 200g of combination modifier and 190g of combination collector to the slurry of the second flotation column roughing operation;

[0035] (4) Combine the primary flotation column rougher concentrate obtained in step (2) and the secondary flotation column rougher concentrate obtained in step (3) to obtain coarse-grained lithium rougher concentrate. After slurry preparation, defoaming and fine grinding are performed, and water is added to adjust the slurry mass percentage concentration to 10%.

[0036] (5) The slurry obtained in step (4) is subjected to a high gradient magnetic separator for a first magnetic separation operation to obtain a first magnetic concentrate and a first magnetic tailings; wherein the magnetic field strength of the first magnetic separation operation is 1.5T;

[0037] (6) The tailings obtained in step (5) are subjected to secondary magnetic separation by a high gradient magnetic separator to obtain secondary magnetic concentrate and secondary magnetic tailings; the secondary magnetic tailings are magnetic tailings; the magnetic field strength of the secondary magnetic separation operation is 1.6T.

[0038] (7) Combine the primary magnetic separation concentrate obtained in step (5) and the secondary magnetic separation concentrate obtained in step (6) to obtain a magnetic separation mixed concentrate, which is lithium concentrate;

[0039] In this embodiment, the lithium flotation recovery rate was 82.8%.

[0040] Example 2: In this example, based on a 100% mass fraction of the composite modifier, sodium carbonate accounts for 55% and sodium hexametaphosphate accounts for 45%; based on a 100% mass fraction of the composite collector, dodecylamine acetate accounts for 40%, sodium cocoyl sulfate accounts for 30%, di(hydroxyethyl)methyldodecyl ammonium chloride accounts for 10%, and ethoxylated alkyl sulfate accounts for 20%.

[0041] like Figure 1 As shown, a flotation pre-enrichment-magnetic separation upgrading method for low-grade lithium iron ore is described, with the following specific steps:

[0042] (1) The low-grade lithium iron ore is crushed and coarsely ground, and then water is added to adjust the mass percentage concentration of the slurry to 34%; wherein the mass percentage content of Li2O in the low-grade lithium iron ore is 0.46%;

[0043] (2) Add the combined modifier and the combined collector to the slurry obtained in step (1) in sequence, and carry out a first flotation column roughing operation in the flotation column to obtain the first flotation column roughing concentrate and the first flotation column roughing tailings; based on each ton of low-grade lithium iron ore, add 500g of combined modifier and 460g of combined collector to the slurry of the first flotation column roughing operation.

[0044] (3) Add a combination modifier and a combination collector to the roughing tailings obtained in step (2) and carry out a second flotation column roughing operation in the flotation column to obtain a second flotation column roughing concentrate and a second flotation column roughing tailings; the second flotation column roughing tailings are flotation tailings; based on each ton of low-grade lithium iron ore, add 250g of combination modifier and 230g of combination collector to the slurry of the second flotation column roughing operation;

[0045] (4) Combine the primary flotation column rougher concentrate obtained in step (2) and the secondary flotation column rougher concentrate obtained in step (3) to obtain coarse-grained lithium rougher concentrate. After slurry preparation, defoaming and fine grinding are performed, and water is added to adjust the slurry mass percentage concentration to 15%.

[0046] (5) The slurry obtained in step (4) is subjected to a high gradient magnetic separator for a first magnetic separation operation to obtain a first magnetic concentrate and a first magnetic tailings; wherein the magnetic field strength of the first magnetic separation operation is 1.6T;

[0047] (6) The tailings obtained from the primary magnetic separation in step (5) are subjected to secondary magnetic separation by a high gradient magnetic separator to obtain secondary magnetic concentrate and secondary magnetic tailings; the secondary magnetic tailings are magnetic tailings; the magnetic field strength of the secondary magnetic separation operation is 1.7T.

[0048] (7) Combine the primary magnetic separation concentrate obtained in step (5) and the secondary magnetic separation concentrate obtained in step (6) to obtain a magnetic separation mixed concentrate, which is lithium concentrate;

[0049] In this embodiment, the lithium flotation recovery rate was 84.1%.

[0050] Example 3: In this example, based on a 100% mass fraction of the composite modifier, sodium carbonate accounts for 65% and sodium hexametaphosphate accounts for 35%; based on a 100% mass fraction of the composite collector, dodecylamine acetate accounts for 45%, sodium cocoyl sulfate accounts for 35%, di(hydroxyethyl)methyldodecyl ammonium chloride accounts for 5%, and ethoxylated alkyl sulfate accounts for 15%.

[0051] like Figure 1 As shown, a flotation pre-enrichment-magnetic separation upgrading method for low-grade lithium iron ore is described, with the following specific steps:

[0052] (1) The low-grade lithium iron ore is crushed and coarsely ground, and then water is added to adjust the mass percentage concentration of the slurry to 40%; wherein the mass percentage content of Li2O in the low-grade lithium iron ore is 0.63%;

[0053] (2) Add the combined modifier and the combined collector to the slurry obtained in step (1) in sequence, and carry out a first flotation column roughing operation in the flotation column to obtain the first flotation column roughing concentrate and the first flotation column roughing tailings; 600g of combined modifier and 540g of combined collector are added to the slurry of the first flotation column roughing operation per ton of low-grade lithium iron ore.

[0054] (3) Add a combination modifier and a combination collector to the roughing tailings obtained in step (2) and carry out a second flotation column roughing operation in the flotation column to obtain a second flotation column roughing concentrate and a second flotation column roughing tailings; the second flotation column roughing tailings are flotation tailings; based on each ton of low-grade lithium iron ore, add 300g of combination modifier and 270g of combination collector to the slurry of the second flotation column roughing operation;

[0055] (4) Combine the primary flotation column rougher concentrate obtained in step (2) and the secondary flotation column rougher concentrate obtained in step (3) to obtain coarse-grained lithium rougher concentrate. After slurry preparation, defoaming and fine grinding are performed, and water is added to adjust the slurry mass percentage concentration to 20%.

[0056] (5) The slurry obtained in step (4) is subjected to a high gradient magnetic separator for a first magnetic separation operation to obtain a first magnetic concentrate and a first magnetic tailings; wherein the magnetic field strength of the first magnetic separation operation is 1.7T;

[0057] (6) The tailings obtained from the primary magnetic separation in step (5) are subjected to secondary magnetic separation by a high gradient magnetic separator to obtain secondary magnetic concentrate and secondary magnetic tailings; the secondary magnetic tailings are magnetic tailings; the magnetic field strength of the secondary magnetic separation operation is 1.8T.

[0058] (7) Combine the primary magnetic separation concentrate obtained in step (5) and the secondary magnetic separation concentrate obtained in step (6) to obtain a magnetic separation mixed concentrate, which is lithium concentrate;

[0059] In this embodiment, the lithium flotation recovery rate was 85.5%.

[0060] The specific embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for pre-enrichment and magnetic separation upgrading of low-grade lithium iron ore by flotation, characterized in that, The specific steps are as follows: (1) The low-grade lithium mica ore is crushed and coarsely ground, and then water is added to adjust the slurry mass percentage concentration to 28-40%; (2) Add combined modifier and combined collector to the slurry obtained in step (1) in sequence, and carry out a first flotation column roughing operation in the flotation column to obtain the first flotation column roughing concentrate and the first flotation column roughing tailings; (3) Add a combination modifier and a combination collector to the primary flotation column roughing tailings obtained in step (2) and perform secondary flotation column roughing operation in the flotation column to obtain secondary flotation column roughing concentrate and secondary flotation column roughing tailings; the secondary flotation column roughing tailings are flotation tailings. (4) Combine the primary flotation column rougher concentrate obtained in step (2) and the secondary flotation column rougher concentrate obtained in step (3) to obtain coarse-grained lithium rougher concentrate. After slurry preparation, defoaming and fine grinding are performed, and water is added to adjust the slurry mass percentage concentration to 10~20%. (5) The slurry obtained in step (4) is subjected to a high gradient magnetic separator for a first magnetic separation operation to obtain a first magnetic concentrate and a first magnetic tailings; (6) The tailings obtained from the primary magnetic separation in step (5) are subjected to secondary magnetic separation by a high-gradient magnetic separator to obtain secondary magnetic concentrate and secondary magnetic tailings; the secondary magnetic tailings are magnetic tailings. (7) The primary magnetic separation concentrate obtained in step (5) and the secondary magnetic separation concentrate obtained in step (6) are combined to obtain a magnetic separation mixed concentrate, which is lithium concentrate; The combined modifier is a mixture of sodium carbonate and sodium hexametaphosphate, and the combined collector is a mixture of dodecylamine acetate, sodium cocoyl sulfate, di(hydroxyethyl)methyldodecyl ammonium chloride, and ethoxylated alkyl sulfate.

2. The method for flotation pre-enrichment-magnetic separation upgrading of low-grade lithium iron ore according to claim 1, characterized in that: Step (1) The mass percentage of Li2O in low-grade lithium iron ore is 0.29~0.63%.

3. The method for flotation pre-enrichment-magnetic separation upgrading of low-grade lithium iron ore according to claim 1, characterized in that: For every ton of low-grade lithium iron ore, 400-600g of combined modifier and 380-540g of combined collector are added to the slurry in the roughing operation of the first flotation column in step (2).

4. The method for flotation pre-enrichment-magnetic separation upgrading of low-grade lithium iron ore according to claim 1, characterized in that: For every ton of low-grade lithium iron ore, 200-300g of combined modifier and 190-270g of combined collector are added to the slurry in the roughing operation of the secondary flotation column in step (3).

5. The method for flotation pre-enrichment-magnetic separation upgrading of low-grade lithium iron ore according to claim 1, characterized in that: Based on a mass fraction of 100% for the composite modifier, sodium carbonate accounts for 45-65% and sodium hexametaphosphate accounts for 35-55%.

6. The method for flotation pre-enrichment-magnetic separation upgrading of low-grade lithium iron ore according to claim 1, characterized in that: Based on a mass fraction of 100% for the compound collector, the compound collector contains 35-45% dodecylamine acetate, 30-40% sodium cocoyl sulfate, 5-15% di(hydroxyethyl)methyldodecyl ammonium chloride, and 10-20% ethoxylated alkyl sulfate.

7. The method for flotation pre-enrichment-magnetic separation upgrading of low-grade lithium iron ore according to claim 1, characterized in that: Step (5) The magnetic field strength of a single magnetic separation operation is 1.5~1.7T.

8. The method for flotation pre-enrichment-magnetic separation upgrading of low-grade lithium iron ore according to claim 1, characterized in that: The magnetic field strength of the secondary magnetic separation operation in step (6) is 1.6~1.8T.

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