Beneficiation process for refractory lean iron ore

Abstract

The invention provides a beneficiation process for refractory lean iron ore, and belongs to the technical field of beneficiation. According to the method, the spiral chute reselection operation, the flotation operation and the reduction operation are carried out on the tailings generated by the refractory lean iron ore beneficiation process, the tailings of the refractory lean iron ore have the high beneficiation efficiency and the high recovery rate, the total iron grade of the fine iron powder obtained through the reduction operation reaches 97.5% or above, efficient development and utilization of tailings resources of the refractory lean iron ore are achieved, and the economic benefit is increased. And the method has relatively high economic benefits and environmental benefits. The beneficiation process flow of the refractory lean iron ore is simple, equipment operation is stable, the automation degree is high, and industrial production is easy to achieve.

Description

Technical Field

[0001] The present invention relates to the technical field of mineral processing, and in particular to a mineral processing process for refractory and lean iron ore. Background Art

[0002] As an important metal material, steel is widely used in construction, machinery, automobiles, railways, shipbuilding, light industry, home appliances and other industries. The steel industry is a basic industry of the national economy, and its development level is an important indicator of a country's comprehensive strength. With the mining of iron ore at home and abroad, high-grade and easy-to-sort iron ore has been mined out, and there are still a large number of low-grade, complex and difficult-to-select iron ore that urgently needs to be reasonably developed. The efficient development and utilization of this part of difficult-to-select iron ore is of great strategic significance for expanding the utilization rate of iron resources and supporting the supply of iron ore.

[0003] At present, the process for separating lean iron ore usually adopts a combined beneficiation process of grinding-gravity separation-strong magnetic separation-anion reverse flotation. However, the current beneficiation process has the following disadvantages: first, the flotation amount is large, and the reagent consumption is also large; second, the flotation tailings have a high grade, resulting in the iron tailings with fine particle size and high grade (the iron grade of flotation tailings is 20-23.5%, and the iron grade of magnetic tailings is 8-1%) being buried for treatment, resulting in a large waste of resources and environmental pollution. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art, provide a beneficiation process for difficult-to-benefit lean iron ore, and realize the efficient development and utilization of tailings resources.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present disclosure is: to provide a beneficiation process for difficult-to-benefit lean iron ore, comprising the following steps:

[0006] The hard-to-select lean iron ore is subjected to the first grinding operation, the first weak magnetic and strong magnetic separation operation, the second grinding operation, the second weak magnetic and strong magnetic separation operation, the flotation operation, the spiral chute re-selection operation and the reduction operation;

[0007] The overflow product of the first grinding operation enters the first weak magnetic and strong magnetic separation operation;

[0008] The concentrate product of the first weak magnetic and strong magnetic separation operation enters the second grinding operation;

[0009] The overflow product of the second grinding operation enters the second weak magnetic and strong magnetic separation operation;

[0010] The intermediate ore products from the second weak magnetic and strong magnetic separation operation enter the flotation operation;

[0011] The tailings product of the first weak magnetic and strong magnetic separation operation, the tailings product of the second grinding operation, the tailings product of the second weak magnetic and strong magnetic separation operation and the tailings product of the flotation operation are combined as tailings and enter the spiral chute gravity separation operation;

[0012] The primary concentrate product of the spiral chute gravity separation operation enters the reduction operation; the secondary concentrate product of the spiral chute gravity separation operation returns to the flotation operation.

[0013] The present invention discloses a spiral chute re-selection operation, a flotation operation and a reduction operation for the tailings produced by the ore dressing process of the difficult-to-select lean iron ore, and has a high ore dressing efficiency and recovery rate for the tailings of the difficult-to-select lean iron ore. The iron concentrate obtained by the reduction operation has a total iron grade of more than 95.6%, thereby realizing the efficient development and utilization of the tailings resources of the difficult-to-select lean iron ore, and having high economic and environmental benefits.

[0014] In some embodiments, the first grinding operation consists of a first ball mill and a first cyclone; the difficult-to-select lean iron ore enters the first ball mill, and the product of the first ball mill enters the first cyclone; the overflow product of the first cyclone enters the first weak magnetic and strong magnetic separation operation as the overflow product of the first grinding operation, and the sand settling product of the first cyclone returns to the first ball mill for ball milling.

[0015] In some embodiments, the first weak magnetic and strong magnetic separation operation is composed of a first weak magnetic machine, a first thickening and desludging machine and a first strong magnetic machine; the overflow product of the first grinding operation enters the first weak magnetic machine, the tailings product of the first weak magnetic machine enters the first thickening and desludging machine, the concentrate product of the first thickening and desludging machine enters the first strong magnetic machine, the tailings product of the first thickening and desludging machine and the tailings product of the first strong magnetic machine are combined as tailings to enter the spiral chute gravity separation operation, and the concentrate product of the first weak magnetic machine and the concentrate product of the first strong magnetic machine are combined as the concentrate product of the first weak magnetic and strong magnetic separation operation to enter the second grinding operation.

[0016] Specifically, the magnetic force of the first weak magnetic machine is 1500-2000GS; the magnetic force of the first strong magnetic machine is 5000-8000GS.

[0017] In some embodiments, the second grinding operation consists of a second cyclone and a second ball mill; the concentrate product of the first weak magnetic and strong magnetic separation operation enters the second cyclone, the sand settling product of the second cyclone enters the second ball mill, and the product of the second ball mill returns to the second cyclone; the overflow product of the second cyclone enters the second weak magnetic and strong magnetic separation operation as the overflow product of the second grinding operation.

[0018] In some embodiments, the second weak magnetic and strong magnetic separation operation is composed of a second thickener and desludging machine, a second weak magnetic machine, a magnetic gravity separator, a third thickener and desludging machine and a fourth thickener and desludging machine; the overflow product of the second grinding operation enters the second thickener and desludging machine, the concentrate product of the second thickener and desludging machine enters the second weak magnetic machine, the concentrate product of the second weak magnetic machine enters the magnetic gravity separator, and the concentrate product of the magnetic gravity separator is used as the final concentrate product; the tailings product of the second thickener and desludging machine and the tailings product of the magnetic gravity separator are combined and enter the third thickener and desludging machine, the concentrate product of the third thickener and desludging machine enters the fourth thickener and desludging machine, and the concentrate product of the fourth thickener and desludging machine enters the flotation operation as a middling product; the tailings product of the third thickener and desludging machine and the tailings product of the fourth thickener and desludging machine are combined as tailings and enter the spiral chute gravity separation operation.

[0019] Specifically, the magnetic force of the second weak magnetic machine is 1500-2000GS; the magnetic force of the magnetic gravity separator is 5000-8000GS.

[0020] In some embodiments, the flotation operation includes a first flotation, a second flotation, a first scavenging and a first magnetic screen; the intermediate ore products of the second weak magnetic and strong magnetic separation operation enter the first flotation; the concentrate product of the first flotation enters the second flotation, the tailings product of the second flotation returns to the first flotation, and the concentrate product of the first flotation enters the first scavenging; the tailings product of the first scavenging enters the first magnetic screen, the tailings product of the first scavenging and the tailings product of the first magnetic screen are combined as tailings to enter the spiral chute re-selection operation, the tailings product of the first magnetic screen returns to the first flotation, and the concentrate product of the second flotation is used as the final concentrate product.

[0021] Specifically, the magnetic force of the first magnetic screen is 1500-2000 GS.

[0022] Specifically, the present invention adopts a reverse flotation process.

[0023] In some embodiments, the spiral chute gravity separation operation consists of a first spiral chute, a second spiral chute and a third spiral chute; the tailings products of the first weak magnetic and strong magnetic separation operation, the tailings products of the second grinding operation, and the tailings products of the second weak magnetic and strong magnetic separation operation are combined into the tailings pond, the tailings products of the tailings pond enter the tailings reservoir, the tailings products of the first magnetic screen enter the tailings reservoir, the products of the tailings reservoir enter the first spiral chute, the dehydrated tailings products of the tailings pond enter the second spiral chute, the tailings products of the first scavenging enter the third spiral chute, the primary concentrate products of the first spiral chute, the second spiral chute and the third spiral chute are combined as primary concentrate products to enter the reduction operation, and the secondary concentrate products of the first spiral chute, the second spiral chute and the third spiral chute are returned to the flotation operation as secondary concentrate products.

[0024] In some embodiments, the reduction operation comprises the following steps: uniformly mixing the primary concentrate product of the spiral chute gravity separation operation, carbon powder, sodium salt, binder and water, and then forming balls; reducing the balls at 800-1200°C for 1-3h, and screening, crushing and magnetically separating the reduced products to obtain iron ore concentrate.

[0025] The present invention reduces, screens and magnetically separates the primary concentrate product of the spiral chute gravity separation operation to obtain iron concentrate. After testing, the total iron grade of the obtained iron concentrate reaches more than 95.6%.

[0026] Specifically, the average particle size of the balls obtained by the ball making is 10-20 mm, for example, it can be but not limited to 10 mm, 12 mm, 14 mm, 16 mm, 18 mm, 20 mm.

[0027] For example, in different embodiments, the reduction temperature may be, but is not limited to, 800°C, 850°C, 900°C, 950°C, 1000°C, 1050°C, 1100°C, 1150°C, or 1200°C.

[0028] For example, in different embodiments, the reduction time is 1 h, 1.5 h, 2 h, 2.5 h, or 3 h.

[0029] In some embodiments, the sodium salt is sodium carbonate and / or sodium chloride; the binder is at least one of bentonite, starch, and bamboo fiber.

[0030] In some embodiments, based on 100 parts by weight of the primary concentrate product, the weight of the carbon powder is 40-60 parts, the weight of the sodium salt is 15-30 parts, the weight of the binder is 2-4 parts, and the weight of the water is 10-20 parts.

[0031] In the present invention, if the sodium chloride or sodium carbonate is lower than the range, the reduction process reaction will be insufficient; if too little or too much binder is added, the pelletizing effect will be poor; if too little or too much water is added, the pelletizing effect will be poor.

[0032] For example, in different embodiments, the weight of the carbon powder may be, but is not limited to, 40 parts, 42 parts, 44 parts, 46 parts, 48 ​​parts, 50 parts, 52 parts, 54 parts, 56 parts, 58 parts, and 60 parts.

[0033] For example, in different embodiments, the weight of the sodium salt can be, but is not limited to, 15 parts, 17 parts, 19 parts, 21 parts, 23 parts, 25 parts, 28 parts, or 30 parts.

[0034] For example, in different embodiments, the weight of the binder may be, but is not limited to, 2 parts, 2.5 parts, 3 parts, 3.5 parts, or 4 parts.

[0035] For example, in different embodiments, the weight of the water can be 10 parts, 12 parts, 14 parts, 16 parts, 18 parts, or 20 parts.

[0036] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention carries out spiral chute re-selection, flotation and reduction operations on the tailings produced by the beneficiation process of difficult-to-select lean iron ore, has high beneficiation efficiency and recovery rate for the tailings of difficult-to-select lean iron ore, and the total iron grade of the iron concentrate obtained by the reduction operation reaches more than 95.6%, realizing the efficient development and utilization of the tailings resources of difficult-to-select lean iron ore, with high economic and environmental benefits.

[0037] The disclosed ore dressing process for the difficult-to-select lean iron ore is simple, the equipment runs stably, the degree of automation is high, and industrial production can be easily realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a flow chart of the beneficiation process for the difficult-to-benefit lean iron ore disclosed in the present invention. DETAILED DESCRIPTION

[0039] In order to facilitate understanding of the present disclosure, the present disclosure will be described more comprehensively below. However, the present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present disclosure more thorough and comprehensive.

[0040] As used herein:

[0041] "Prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0042] The conjunction "consisting of excludes any unspecified element, step, or component. If used in a claim, this phrase renders the claim closed-ended so that it does not include materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim rather than immediately following the subject matter, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0043] When amount, concentration or other value or parameter is represented by range, preferred range or a series of upper preferred value and lower preferred value, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value and any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when disclosing range "1-5", described range should be interpreted as including range "1-4", "1-3", "1-2", "1-2 and 4-5", "1-3 and 5" etc. When numerical range is described in this article, unless otherwise stated, the range is intended to include its end value and all integers and fractions within the range.

[0044] In these examples, parts and percentages are by mass unless otherwise indicated.

[0045] "Parts by mass" refers to the basic unit of measurement for expressing the mass ratio of multiple components. 1 part can represent any unit mass, such as 1g or 2.689g. If we say that the mass of component A is a parts and the mass of component B is b parts, it means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it means that the mass of component A is aK and the mass of component B is bK (K is an arbitrary number, indicating a multiple factor). It should not be misunderstood that, unlike the mass parts, the sum of the mass of all components is not limited to 100 parts.

[0046] "And / or" is used to indicate that one or both of the stated situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0047] In order to further illustrate the present invention, the beneficiation process of the refractory lean iron ore provided by the present invention is described in detail below in conjunction with the accompanying drawings, but they should not be understood as limiting the protection scope of the present invention.

[0048] like Figure 1 As shown, the present disclosure provides a beneficiation process for difficult-to-benefit lean iron ore, comprising the following steps:

[0049] (1) jaw crushing and secondary crushing are performed on the refractory lean iron ore with a grade of 10-50% to obtain ore particles with an average particle size of 10-50 mm;

[0050] The ore particles with an average particle size of 10-50 mm are screened, the 10-20 mm product obtained by screening is finely crushed, the finely crushed product is returned to the screening, the 10-20 mm product obtained by screening enters the first ball mill for ball milling, the 21-50 mm product obtained by screening is returned to the jaw crusher for crushing, and the silicon dioxide, calcium oxide, ferric oxide and other materials with an iron grade lower than 20% obtained by screening are used as dry dumping tailings;

[0051] The product obtained from the first ball mill enters the Φ500mm cyclone for primary classification, the overflow product of the Φ500mm cyclone enters the Φ350mm cyclone for secondary classification, and the sand settling product of the Φ500mm cyclone and the sand settling product of the Φ350mm cyclone are returned to the first ball mill.

[0052] (2) the overflow product of the Φ350 mm cyclone in step (1) enters the first weak magnetic machine for magnetic separation, the tailings product of the first weak magnetic machine enters the first thickening and desludging machine, the concentrate product of the first thickening and desludging machine enters the first strong magnetic machine, the tailings product of the first thickening and desludging machine and the tailings product of the first strong magnetic machine are combined as tailings to enter the spiral chute gravity separation operation, and the concentrate product of the first weak magnetic machine and the concentrate product of the first strong magnetic machine are combined as the concentrate product of the first weak magnetic and strong magnetic separation operation to enter the second grinding operation;

[0053] (3) the concentrate product of the first weak magnetic and strong magnetic separation operation obtained in step (2) enters a Φ150 mm cyclone, the sand settling product of the Φ150 mm cyclone enters a second ball mill, and the product of the second ball mill returns to the Φ150 mm cyclone; the overflow product of the Φ150 mm cyclone enters a second weak magnetic and strong magnetic separation operation as the overflow product of the second grinding operation;

[0054] (4) the overflow product of the second grinding operation obtained in step (3) enters the second thickener and desludging machine, the concentrate product of the second thickener and desludging machine enters the second weak magnetic machine, the concentrate product of the second weak magnetic machine enters the magnetic gravity separator, and the concentrate product of the magnetic gravity separator is used as the final concentrate product; the tailings product of the second thickener and desludging machine and the tailings product of the magnetic gravity separator are combined and enter the third thickener and desludging machine, the concentrate product of the third thickener and desludging machine enters the fourth thickener and desludging machine, and the concentrate product of the fourth thickener and desludging machine enters the flotation operation as the middling product; the tailings product of the third thickener and desludging machine and the tailings product of the fourth thickener and desludging machine are combined as tailings and enter the spiral chute gravity separation operation;

[0055] (5) the intermediate ore product of the second weak magnetic and strong magnetic separation operation obtained in step (4) enters the first flotation machine for roughing, the concentrate product of the first flotation machine enters the second flotation machine for cleaning, the tailings product of the second flotation is returned to the first flotation machine, the concentrate product of the first flotation machine enters the first scavenger for scavenging; the tailings product of the first scavenger enters the first magnetic screen for magnetic screening, the tailings product of the first scavenger and the tailings product of the first magnetic screen are combined as tailings and enter the spiral chute for re-selection, the tailings product of the second flotation cleaning machine is returned to the first flotation machine, and the iron concentrate product of the second flotation machine is used as the final concentrate product;

[0056] (6) The tailings product of the first thickener and desludging machine in step (2), the tailings product of the first strong magnetic machine, the tailings product of the third thickener and desludging machine in step (4), and the tailings product of the fourth thickener and desludging machine are combined and entered into the tailings pond, and the tailings product of the first magnetic screen machine in step (5) is entered into the tailings pond; the products in the tailings pond are pumped to the spiral chute, the dehydrated tailings product enters the tailings pond, the products of the tailings pond enter the first spiral chute, the dehydrated tailings product of the tailings pond enters the second spiral chute, the tailings product of the first scavenging enters the third spiral chute, the primary concentrate product of the first spiral chute, the primary concentrate product of the second spiral chute, and the primary concentrate product of the third spiral chute are combined as the primary concentrate product to enter the reduction operation, and the secondary concentrate product of the first spiral chute, the secondary concentrate product of the second spiral chute, and the secondary concentrate product of the third spiral chute are combined as the secondary concentrate product to return to the flotation operation;

[0057] (7) uniformly mixing the primary concentrate product obtained in step (6), carbon powder, sodium salt, bentonite and water, and then forming balls to obtain balls with an average particle size of 10-20 mm. After drying the balls with an average particle size of 10-20 mm, the balls are placed in a crucible, and then the crucible containing the balls is placed in a heating furnace, heated to 1000° C. at a heating rate of 10° C. / min, kept warm for 2 hours, and then cooled to room temperature with the furnace to obtain a reduction product; wherein, based on 100 parts by weight of the primary concentrate product, the weight of the carbon powder is 50 parts, the weight of the sodium salt is 20 parts, the weight of the bentonite is 3 parts, and the weight of the water is 15 parts;

[0058] The reduction products are screened, the sieve-surface products are reduction balls, and the sieve-surface products are non-magnetic powders such as mineral powder and coal powder;

[0059] The reducing balls are crushed to obtain reducing powder with an average particle size of 150-200 meshes;

[0060] The reduced powder with an average particle size of 150-200 mesh is subjected to wet magnetic separation to obtain iron concentrate;

[0061] After testing, the total iron grade of the obtained iron ore concentrate reached more than 97.5%, and the recovery rate was more than 94%.

[0062] In order to prevent the iron ore concentrate from oxidation, the obtained iron ore concentrate needs to be dried and sealed.

[0063] By using the beneficiation process for difficult-to-select lean iron ore of the present invention, the concentrate product of the magnetic gravity separator in step (4) and the iron concentrate product of the second flotation machine in step (5) are used as the final concentrate product, and the iron grade of the final concentrate product is 61%, the yield is 85%, and the recovery rate is 85%.

[0064] Finally, it should be noted that the above embodiments are used to illustrate the technical solution of the present disclosure rather than to limit the protection scope of the present disclosure. Although the present disclosure has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present disclosure can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present disclosure.

Claims

1. A beneficiation process for difficult-to-benefit lean iron ore, characterized in that: The following steps are involved: The hard-to-select lean iron ore is subjected to the first grinding operation, the first weak magnetic and strong magnetic separation operation, the second grinding operation, the second weak magnetic and strong magnetic separation operation, the flotation operation, the spiral chute re-selection operation and the reduction operation; The overflow product of the first grinding operation enters the first weak magnetic and strong magnetic separation operation; The concentrate product of the first weak magnetic and strong magnetic separation operation enters the second grinding operation; The overflow product of the second grinding operation enters the second weak magnetic and strong magnetic separation operation; The intermediate ore products from the second weak magnetic and strong magnetic separation operation enter the flotation operation; The tailings product of the first weak magnetic and strong magnetic separation operation, the tailings product of the second grinding operation, the tailings product of the second weak magnetic and strong magnetic separation operation and the tailings product of the flotation operation are combined as tailings and enter the spiral chute gravity separation operation; The primary concentrate product of the spiral chute gravity separation operation enters the reduction operation; the secondary concentrate product of the spiral chute gravity separation operation returns to the flotation operation.

2. The ore dressing process for refractory lean iron ore according to claim 1, characterized in that: The first grinding operation consists of a first ball mill and a first cyclone; the difficult-to-select lean iron ore enters the first ball mill, and the product of the first ball mill enters the first cyclone; the overflow product of the first cyclone enters the first weak magnetic and strong magnetic separation operation as the overflow product of the first grinding operation, and the sand settling product of the first cyclone returns to the first ball mill for ball milling.

3. The ore dressing process for refractory lean iron ore according to claim 1, characterized in that: The first weak magnetic and strong magnetic separation operation consists of a first weak magnetic machine, a first thickening and desludging machine and a first strong magnetic machine; the overflow product of the first grinding operation enters the first weak magnetic machine, the tailings product of the first weak magnetic machine enters the first thickening and desludging machine, the concentrate product of the first thickening and desludging machine enters the first strong magnetic machine, the tailings product of the first thickening and desludging machine and the tailings product of the first strong magnetic machine are combined as tailings to enter the spiral chute gravity separation operation, and the concentrate product of the first weak magnetic machine and the concentrate product of the first strong magnetic machine are combined as the concentrate product of the first weak magnetic and strong magnetic separation operation to enter the second grinding operation.

4. The ore dressing process for refractory lean iron ore according to claim 1, characterized in that: The second grinding operation consists of a second cyclone and a second ball mill; the concentrate product of the first weak magnetic and strong magnetic separation operation enters the second cyclone, the sand settling product of the second cyclone enters the second ball mill, and the product of the second ball mill returns to the second cyclone; the overflow product of the second cyclone enters the second weak magnetic and strong magnetic separation operation as the overflow product of the second grinding operation.

5. The ore dressing process for refractory lean iron ore according to claim 1, characterized in that: The second weak magnetic and strong magnetic separation operation consists of a second thickener and desludging machine, a second weak magnetic machine, a magnetic gravity separator, a third thickener and desludging machine and a fourth thickener and desludging machine; the overflow product of the second grinding operation enters the second thickener and desludging machine, the concentrate product of the second thickener and desludging machine enters the second weak magnetic machine, the concentrate product of the second weak magnetic machine enters the magnetic gravity separator, and the concentrate product of the magnetic gravity separator is used as the final concentrate product; the tailings product of the second thickener and desludging machine and the tailings product of the magnetic gravity separator are combined and enter the third thickener and desludging machine, the concentrate product of the third thickener and desludging machine enters the fourth thickener and desludging machine, and the concentrate product of the fourth thickener and desludging machine enters the flotation operation as a middling product; the tailings product of the third thickener and desludging machine and the tailings product of the fourth thickener and desludging machine are combined as tailings and enter the spiral chute gravity separation operation.

6. The ore dressing process for refractory lean iron ore according to claim 1, characterized in that: The flotation operation includes the first flotation, the second flotation, the first scavenging and the first magnetic screen; the intermediate ore products of the second weak magnetic and strong magnetic separation operation enter the first flotation; the concentrate products of the first flotation enter the second flotation, the tailing products of the second flotation return to the first flotation, and the concentrate products of the first flotation enter the first scavenging; the tailing products of the first scavenging enter the first magnetic screen, the tailing products of the first scavenging and the tailings products of the first magnetic screen are combined as tailings to enter the spiral chute re-selection operation, the tailings products of the first magnetic screen return to the first flotation, and the concentrate products of the second flotation are used as the final concentrate products.

7. The ore dressing process for refractory lean iron ore according to claim 6, characterized in that: The spiral chute gravity separation operation consists of a first spiral chute, a second spiral chute and a third spiral chute; the tailings products of the first weak magnetic and strong magnetic separation operation, the tailings products of the second grinding operation, and the tailings products of the second weak magnetic and strong magnetic separation operation are combined into the tailings pond, the tailings products of the tailings pond enter the tailings reservoir, the tailings products of the first magnetic screen enter the tailings reservoir, the products of the tailings reservoir enter the first spiral chute, the dehydrated tailings products of the tailings pond enter the second spiral chute, the tailings products of the first scavenging selection enter the third spiral chute, the primary concentrate products of the first spiral chute, the second spiral chute and the third spiral chute are combined as primary concentrate products to enter the reduction operation, and the secondary concentrate products of the first spiral chute, the second spiral chute and the third spiral chute are returned to the flotation operation as secondary concentrate products.

8. The ore dressing process for refractory lean iron ore according to claim 1, characterized in that: The reduction operation comprises the following steps: uniformly mixing the primary concentrate product of the spiral chute gravity separation operation, carbon powder, sodium salt, binder and water, and then forming balls; reducing the balls at 800-1200° C. for 1-3 hours, and screening, crushing and magnetically separating the obtained reduction products to obtain iron concentrate.

9. The ore dressing process for refractory lean iron ore according to claim 8, characterized in that: The sodium salt is sodium carbonate and / or sodium chloride; the binder is at least one of bentonite, starch and bamboo fiber.

10. The ore dressing process for refractory lean iron ore according to claim 8, characterized in that: Based on 100 parts by weight of the primary concentrate product, the weight of the carbon powder is 40-60 parts, the weight of the sodium salt is 15-30 parts, the weight of the binder is 2-4 parts, and the weight of the water is 10-20 parts.

Images