Ultra-low-grade magnetite final powder process combining high-pressure roller mill with two-stage dry separation

Abstract

The invention belongs to the technical field of ultra-lean magnetite crushing and beneficiation, and particularly provides an ultra-lean magnetite final powdering process combining a high-pressure roller mill with two-stage dry separation, which comprises the following specific steps: ultra-fine crushing, screening, first-stage dry magnetic separation and second-stage dry magnetic separation, and the ores return to the high-pressure roller mill to be crushed, the first to fourth steps are repeated, and the waste rocks are directly thrown out. According to the process, the secondary dry type magnetic separation process is added in the follow-up process of the screening process, oversize ore is subjected to secondary dry type magnetic separation and then returns to the high-pressure roller mill, the treatment principle that throwing can be carried out early, throwing can be carried out early, and collecting can be carried out early is achieved, waste rock and part of ore reaching the monomer dissociation degree are separated in advance, and the treatment capacity of the high-pressure roller mill is reduced; therefore, the problem that the treatment effect of the high-pressure roller mill final powder process on the ultra-lean magnetite is poor due to the fact that the disseminated particle size of the magnetite is not uniform is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of ultralow-grade magnetite crushing and beneficiation, and particularly provides an ultralow-grade magnetite final powder process combining a high-pressure roller mill and secondary dry separation. Background Art

[0002] Ultralow-grade magnetite refers to iron-containing rocks with magnetic iron content lower than the general industrial index requirements of magnetite ore that needs to be beneficiated in the current specifications and can be exploited under the current technical and economic conditions.

[0003] At present, high-pressure roller mills have been widely applied in the production of ultralow-grade magnetite mines. Since the products after crushing by high-pressure roller mills have fine particle sizes and can cause cracks inside the ore, the subsequent grinding energy consumption can be greatly reduced.

[0004] In the conventional high-pressure roller mill final powder process, the content of -200 mesh in the crushed material can reach 20% - 25%. Based on this, the high-pressure roller mill final powder process has also been proposed in the industry, that is, using a high-pressure roller mill to crush the material to more than 60% -200 mesh. In this process, the oversize material is directly returned to the high-pressure roller mill to form a closed circuit. However, due to the finer product particle size requirements, the circulating load of the high-pressure roller mill will be very large, and the energy consumption and wear will increase significantly, and the economic advantage will disappear. It can be seen that the high-pressure roller mill final powder process has poor treatment effect on ultralow-grade magnetite, is not applicable to ultralow-grade magnetite, and cannot be widely applied to the treatment of ultralow-grade magnetite. Summary of the Invention

[0005] To solve the above technical problems, the technical solution adopted by the present invention is: an ultralow-grade magnetite final powder process combining a high-pressure roller mill and secondary dry separation, and the specific steps include:

[0006] Step 1: Ultra-fine crushing;

[0007] Using a high-pressure roller mill, feeding the magnetite after fine crushing into the high-pressure roller mill for a first-stage high-pressure roller grinding operation to obtain an ultra-fine crushed product;

[0008] Step 2: Screening;

[0009] Screening the ultra-fine crushed product with a powder sieve;

[0010] The undersize material then enters the subsequent beneficiation process;

[0011] The oversize material enters the first-stage dry magnetic separation;

[0012] Step 3: First-stage dry magnetic separation;

[0013] Selecting the dissociated magnetite, and the tailings thrown out enter the second-stage dry magnetic separation;

[0014] Step 4: Secondary dry magnetic separation;

[0015] Select the iron ore-containing ore and discard part of the waste rock. The ore is returned to the high-pressure roller mill for crushing. Repeat Steps 1 to 4, and the waste rock is directly discarded.

[0016] Furthermore, a suspension dry separator is used for the primary dry magnetic separation.

[0017] Furthermore, a drum dry separator is used for the secondary dry magnetic separation.

[0018] Furthermore, the primary dry magnetic separation has two magnetic field strength schemes, one is a low-intensity magnetic field and the other is a medium-intensity magnetic field.

[0019] Furthermore, the low-intensity magnetic field strength of the primary dry magnetic separation is 500 - 1000 Oersteds, and the medium-intensity magnetic field strength of the primary dry magnetic separation is 1000 - 1500 Oersteds.

[0020] Furthermore, the magnetic field strength of the secondary dry magnetic separation is 1800 - 2000 Oersteds.

[0021] The beneficial effects of using the present invention are as follows:

[0022] In this process, a secondary dry magnetic separation process is added after the screening process. The screened ore is returned to the high-pressure roller mill after secondary dry magnetic separation. Adhering to the principle of discarding early and collecting early, waste rock and part of the ore that has reached the monomer dissociation degree are separated in advance, reducing the amount of ore to be processed by the high-pressure roller mill. Utilizing the characteristics of uneven dissemination size of ultra-poor magnetite, the process is optimized, thus resolving the problem of poor treatment effect caused by the high cycle load in the final powder process.

[0023] The high-pressure roller mill final powder process after process optimization and improvement can be applied to the treatment of ultra-poor magnetite, replacing the single-stage ball mill, saving 40 - 50% of the grinding energy consumption, and reducing the cycle load of the high-pressure roller mill by 100% - 160%. Description of the Drawings

[0024] Figure 1 It is the process flow chart of the present invention. Detailed Embodiments

[0025] The present invention will be described in detail below with reference to the drawings.

[0026] Refer to Figure 1 , an ultra-poor magnetite final powder process combining a high-pressure roller mill and secondary dry separation, the specific steps include:

[0027] Step 1: Ultra-fine grinding;

[0028] Use a high-pressure roller mill to feed the finely crushed magnetite into the high-pressure roller mill for a first-stage high-pressure roller grinding operation to obtain an ultrafine grinding product.

[0029] Step 2: Screening;

[0030] Screen the ultrafine grinding product using a powder sieve;

[0031] The undersize material then enters the subsequent ore dressing process;

[0032] The oversize material enters the first-stage dry magnetic separation.

[0033] Step 3: First-stage dry magnetic separation;

[0034] Use a suspension dry separator to select the dissociated magnetite, and the tailings thrown out enter the second-stage dry magnetic separation;

[0035] Specifically, the first-stage dry magnetic separation has two magnetic field intensity schemes, one is a low-intensity magnetic field and the other is a medium-intensity magnetic field;

[0036] Among them, the low-intensity magnetic field scheme is used to select high-grade iron concentrate powder, which is the concentrate and will not be subjected to any further separation;

[0037] The medium-intensity magnetic field scheme is used to select the middlings, and the middlings are returned to the high-pressure roller mill for secondary grinding.

[0038] Preferably, the low-intensity magnetic field intensity is 500 - 1000 oersteds, and the medium-intensity magnetic field intensity is 1000 - 1500 oersteds.

[0039] Step 4: Second-stage dry magnetic separation;

[0040] Use a drum dry separator to select the iron-bearing ore and throw out part of the waste rock. The ore is returned to the high-pressure roller mill for crushing, and steps 1 to 4 are repeated. The waste rock is directly thrown out.

[0041] Preferably, the magnetic field intensity is 1800 - 2000 oersteds.

[0042] Example 1

[0043] The parameters of the ore processed in this example are: iron grade TFe = 15.62%, magnetic iron grade mFe = 10.28%, and magnetic ratio = 62.31%;

[0044] After the ore is processed by the conventional crushing process, the particle size is 10 - 12 mm;

[0045] The parameters of the high-pressure roller mill used in this example are: working pressure is 4.5 MPa, linear velocity is 1.1 m / s, and roll spacing is 7 mm;

[0046] The specific steps are as follows:

[0047] Step 1: Ultrafine grinding;

[0048] Feed magnetite into a high-pressure roller mill for a one-stage high-pressure roller grinding operation to obtain an ultrafine grinding product.

[0049] Step 2: Screening;

[0050] Use a powder sieve to screen the ultrafine grinding product;

[0051] The particle size of the material passing through the sieve with -200 mesh accounts for 80%, and then it enters the subsequent ore dressing process;

[0052] The oversize material enters the first-stage dry magnetic separation.

[0053] Step 3: First-stage dry magnetic separation;

[0054] Use a suspension dry separator to select the dissociated magnetite, and the tailings thrown out enter the second-stage dry magnetic separation;

[0055] The two magnetic field intensity schemes of the suspension dry separator are respectively, one magnetic field intensity is 800 Oe, and the other magnetic field intensity is 1000 Oe;

[0056] A smaller magnetic field intensity can ensure the grade of the iron concentrate powder, directly select the final iron concentrate powder, and no further separation is required subsequently. 10% - 15% of the iron concentrate powder can be selected;

[0057] The medium-intensity magnetic field scheme is used to select the middlings and ensure the recovery rate of the middlings. 20% - 25% of the middlings can be selected, and this part of the middlings needs to enter the second-stage grinding treatment.

[0058] Step 4: Second-stage dry magnetic separation;

[0059] Set the magnetic field intensity of the drum dry separator to 2000 Oe, select the iron-containing ore and throw out part of the waste rock. The ore returns to the high-pressure roller mill for crushing, repeating Steps 1 to 4, and the waste rock is directly thrown out. About 20% of the waste rock can be thrown out.

[0060] The above content is only the preferred embodiment of the present invention. For those of ordinary skill in the art, many changes can be made in the specific implementation manners and application scopes according to the idea of the present invention. As long as these changes do not depart from the concept of the present invention, they all belong to the protection scope of the present invention.

Claims

1. A process for the final powder of ultra-poor magnetite by combining a high-pressure roller mill and secondary dry separation, characterized in that: The specific steps include: Step 1: Ultrafine grinding; Using a high-pressure roller mill, feed the magnetite that has been finely crushed into the high-pressure roller mill for a first-stage high-pressure roller grinding operation to obtain an ultrafine grinding product; Step 2: Screening; Use a powder sieve to screen the ultrafine grinding product; The material passing through the sieve then enters the subsequent ore dressing process; The material retained on the sieve enters the first-stage dry magnetic separation; Step 3: First-stage dry magnetic separation; Select the dissociated magnetite, and the tailings thrown out enter the second-stage dry magnetic separation; Step 4: Second-stage dry magnetic separation; Select the iron-containing ore and throw out some waste rock. The ore is returned to the high-pressure roller mill for crushing, and steps 1 to 4 are repeated. The waste rock is directly thrown out.

2. The ultra-poor magnetite final powder process of high-pressure roll mill combined with secondary dry separation according to claim 1, characterized in that: The first-stage dry magnetic separation uses a suspension dry separator.

3. The ultra-poor magnetite final powder process combining a high-pressure roller mill with secondary dry separation according to claim 1, wherein: The second-stage dry magnetic separation uses a drum dry separator.

4. The ultra-poor magnetite final powder process combining a high-pressure roller mill with secondary dry separation according to claim 1, characterized in that: The first-stage dry magnetic separation has two magnetic field intensity schemes, one is a low-intensity magnetic field and the other is a medium-intensity magnetic field.

5. A process for producing ultrapoor magnetite final powder by combining a high-pressure roller mill with secondary dry separation according to claim 1, characterized in that: The low-intensity magnetic field intensity of the first-stage dry magnetic separation is 500 - 1000 Oersteds, and the medium-intensity magnetic field intensity of the first-stage dry magnetic separation is 1000 - 1500 Oersteds.

6. The ultra-poor magnetite final powder process combining a high-pressure roller mill with secondary dry separation according to claim 1, characterized in that: The magnetic field intensity of the second-stage dry magnetic separation is 1800 - 2000 Oersteds.

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