Grinding and separation process for superfine iron powder

Abstract

The invention relates to an iron ore powder grinding and separation technology, and particularly discloses a superfine iron powder grinding and separation process which mainly comprises the following steps: pre-separation and magnetic separation, first-stage grinding, roughing and magnetic separation, screening and grading, concentration and magnetic separation, second-stage grinding and refining and slag-reducing magnetic separation to obtain superfine iron powder. According to the method, fine-particle iron ore is ground to reach the standard fineness, meanwhile, narrower size fraction distribution can be achieved, the granularity of finished products is uniform, the multistage magnetic separator is arranged, the maximum mineral separation effect can be achieved, the recovery rate of magnetic iron is greatly improved, and meanwhile, the grade of fine iron powder can be remarkably improved by using the refining and slag-reducing magnetic separator.

Description

Technical Field

[0001] The present invention relates to iron ore grinding and beneficiation technology, and specifically to a grinding and beneficiation process for ultrafine iron powder. Background Art

[0002] Iron ore grinding is a complex and crucial industrial process that starts with massive iron ore.

[0003] In the existing process, equipment such as jaw crushers and cone crushers are used for crushing, reducing the iron ore from large chunks to a particle size range of a few centimeters to dozens of centimeters, initially shrinking its volume. Then, the crushed iron ore enters grinding equipment such as ball mills and rod mills. The purpose of iron ore grinding is, on the one hand, for ore dressing. Grinding can significantly increase the specific surface area of iron ore, enabling the beneficiation reagents to fully contact the ore, thereby significantly improving the beneficiation efficiency, enabling more accurate selection of high-grade iron concentrate, and increasing resource utilization rate.

[0004] In actual operation, it is found that serpentine tailings (asbestos tailings) contain iron concentrate powder and have certain extraction value. However, their initial grade is low and they need to be ground fine and beneficiated to better carry out smelting. After experiments, in some low-grade iron concentrate raw ores, the same process can also be used for grinding and beneficiation to improve the smelting efficiency. Summary of the Invention

[0005] In view of the above technical problems, the present invention provides a grinding and beneficiation process for ultrafine iron powder.

[0006] To solve the above problems, the present invention provides a grinding and beneficiation process for ultrafine iron powder, which is characterized in that: preparing materials, the materials are mineral raw materials with a particle size of about 3 mm and a magnetic iron grade of more than 24%, and the specific grinding and beneficiation steps are as follows:

[0007] S1: Pre-selecting magnetic separation for the mineral raw materials, the magnetic separator adsorbs the magnetic raw materials in the mineral raw materials to obtain material A, and the substances that cannot be adsorbed by the magnetic separator are discharged;

[0008] S2: Grinding the material A in one stage to obtain material B;

[0009] S3: Conducting rough magnetic separation on the material B, the magnetic separation adsorbs to obtain material C, and the materials that cannot be magnetically separated are discharged;

[0010] S4: Conducting screening and classification on the material C, concentrating and magnetically separating the materials with a fineness of minus 200 mesh to obtain material D, and sending the remaining materials coarser than minus 200 mesh to the S2 step for repeated grinding;

[0011] S5: Conducting two-stage grinding on the material D, grinding and screening are carried out simultaneously, screening the materials with a fineness lower than minus 400 mesh for re-magnetic separation, and obtaining ultrafine iron concentrate powder after magnetic separation.

[0012] Further, the magnetic separation in both step S1 and step S3 uses a magnetic separator.

[0013] Further, the magnetic separation in step S5 is a three-stage magnetic separation for upgrading and slag reduction.

[0014] Further, the grinding devices used in step S2 are all ball mills.

[0015] Further, a hydrocyclone is used for screening in step S4, and a magnetic separator is used for concentration magnetic separation.

[0016] Further, the grinding step in step S5 uses a ball mill, and the ball mill has the function of grinding and screening simultaneously.

[0017] Further, the ultrafine iron concentrate powder obtained in step S5 is dehydrated to make the water content lower than 10.5%.

[0018] Further, a disc filter is used for the dehydration step.

[0019] The present invention has the following beneficial effects compared with the prior art:

[0020] 1. While grinding fine-grained iron ore to the standard fineness, the present invention can also achieve a relatively narrow particle size distribution, with uniform finished product particle size. A multi-stage magnetic separator is set up, which can exert the maximum beneficiation effect, greatly improving the recovery rate of magnetic iron. At the same time, a magnetic separator for upgrading and slag reduction is used, which can significantly improve the grade of iron concentrate powder.

[0021] 2. The fineness of the raw materials of the present invention is below 3 mm, which conforms to the principle of "more crushing and less grinding" in the iron ore grinding and beneficiation industry. By using magnetic separation multiple times instead of screening and grinding, the grinding cost can be effectively reduced. Specific Embodiments

[0022] The present invention and its effects will be further described below through examples.

[0023] A grinding and beneficiation process for ultrafine iron powder, preparing materials. The materials are mineral raw materials with a particle size of about 3 mm and a magnetic iron grade of more than 24%. The specific grinding and beneficiation steps are as follows:

[0024] S1: The mineral raw materials are subjected to preliminary magnetic separation. The magnetic separator adsorbs the magnetic raw materials in the mineral raw materials to obtain material A, and the substances that cannot be adsorbed by the magnetic separator are discharged. Among them, the model of the magnetic separator used for magnetic separation is CTY1545--5000GS;

[0025] S2: Material A is ground in one stage to obtain material B, and all the grinding devices are ball mills;

[0026] S3: Coarsely separate and magnetically separate Material B to magnetically adsorb and obtain Material C, and discharge the materials that cannot be magnetically separated. The model of the magnetic separator is CTB1545--4000GS.

[0027] S4: Screen and classify Material C, concentrate and magnetically separate the materials with a fineness of minus 200 mesh to obtain Material D, and send the remaining materials coarser than minus 200 mesh back to Step S2 for repeated fine grinding. A hydrocyclone is used for screening. The model of the concentrate magnetic separator is NCTB1540--4000GS.

[0028] S5: Grind Material D in the second stage. Grinding and screening are carried out simultaneously. Screen the materials with a fineness lower than minus 400 mesh for re-magnetic separation, and obtain superfine iron concentrate powder after magnetic separation. In the grinding step, a ball mill is used, and the ball mill has the function of grinding and screening on the side. The second-stage ball mill is an ASAM mill, with a model of 3900L. The models of the three-stage refining and slag-reducing magnetic separators are JCTN1540--5000GS, JCTN1240--4000GS, and JCTN1240--3000GS in sequence.

[0029] Dehydrate the obtained superfine iron concentrate powder to reduce its water content.

[0030] Example 1: Pre-magnetically separate the mineral raw materials. Add water during magnetic separation. The magnetic separator adsorbs the magnetic raw materials in the mineral raw materials, and discharges the substances that cannot be adsorbed by the magnetic separator. The magnetic iron grade of the material reaches 30%. Use a ball mill to finely grind the material in the first stage until the passing rate of -200 mesh reaches 60%. Use a coarse separation magnetic separator to coarsely separate and magnetically separate the material, and the magnetic iron grade reaches 40%. Discharge the substances that cannot be magnetically separated; use a hydrocyclone to classify the magnetically separated materials. The material at the underflow port of this hydrocyclone is coarser, and the coarser material is returned to the first-stage ball mill for re-grinding. The passing rate of the overflow port for minus 200 mesh is 80%. Conduct concentrate magnetic separation to obtain a material with a magnetic iron grade of 50% and a water content of less than 30%. Grind the material in the second stage and apply pressure when it enters the fine grinding ball mill. This ball mill is equipped with its own classification system. Grinding and screening are carried out simultaneously. Screen the materials with a passing rate of minus 400 mesh of 90% for re-magnetic separation. Pass through three series-connected refining and slag-reducing magnetic separators, and obtain superfine iron concentrate powder after magnetic separation. The final iron concentrate powder grade is 62%. Then use a disc filter for dehydration to reduce the water content to 10.5% to obtain the finished iron concentrate powder.

[0031] Example 2: The mineral raw materials are pre-selected by magnetic separation. Water is added during magnetic separation. The magnetic separator adsorbs the magnetic raw materials in the mineral raw materials, and the substances that cannot be adsorbed by the magnetic separator are discharged. The magnetic iron grade of the material reaches 33%. The material is ground in one stage using a ball mill until the passing rate of -200 mesh is 65%. The material is roughly separated by magnetic separation using a roughing magnetic separator, and the magnetic iron grade reaches 45%. The substances that cannot be magnetically separated are discharged. A hydrocyclone is used to classify the magnetically separated material. The material at the underflow port of this hydrocyclone is coarser, and the coarser material is returned to the ball mill at one end for re-grinding. The passing rate of the overflow port for -200 mesh is 75%, and then it is subjected to concentrated magnetic separation to obtain a material with a magnetic iron grade of 53% and a moisture content of less than 28%. The material is ground in the second stage. Pressure is applied when it enters the fine grinding ball mill. This ball mill is equipped with its own classification system, and grinding and screening are carried out simultaneously. The material with a screening fineness of a passing rate of 88% for -400 mesh is subjected to magnetic separation again. Through three series-connected magnetic separators for upgrading and slag reduction, ultrafine iron concentrate powder is obtained after magnetic separation. The final iron concentrate powder grade is 65%. Then a disk filter is used for dehydration to reduce the moisture content to 10%, and the finished iron concentrate powder is obtained.

[0032] Example 3: The mineral raw materials are pre-selected by magnetic separation. Water is added during magnetic separation. The magnetic separator adsorbs the magnetic raw materials in the mineral raw materials, and the substances that cannot be adsorbed by the magnetic separator are discharged. The magnetic iron grade of the material reaches 35%. The material is ground in one stage using a ball mill until the passing rate of -200 mesh is 70%. The material is roughly separated by magnetic separation using a roughing magnetic separator, and the magnetic iron grade reaches 43%. The substances that cannot be magnetically separated are discharged. A hydrocyclone is used to classify the magnetically separated material. The material at the underflow port of this hydrocyclone is coarser, and the coarser material is returned to the ball mill at one end for re-grinding. The passing rate of the overflow port for -200 mesh is 80%, and then it is subjected to concentrated magnetic separation to obtain a material with a magnetic iron grade of 55% and a moisture content of less than 25%. The material is ground in the second stage. Pressure is applied when it enters the fine grinding ball mill. This ball mill is equipped with its own classification system, and grinding and screening are carried out simultaneously. The material with a screening fineness of a passing rate of 92% for -400 mesh is subjected to magnetic separation again. Through three series-connected magnetic separators for upgrading and slag reduction, ultrafine iron concentrate powder is obtained after magnetic separation. The final iron concentrate powder grade is 67%. Then a disk filter is used for dehydration to reduce the moisture content to 9.5%, and the finished iron concentrate powder is obtained.

[0033] The following is a comparison by changing the process steps in the present invention:

[0034] Comparative Example 1. In this comparative example, the concentrated magnetic separation step is cancelled, and the specific steps are as follows: The mineral raw materials are preselected by magnetic separation. Water is added during magnetic separation, and the magnetic raw materials in the mineral raw materials are adsorbed by the magnetic separator. The substances that cannot be adsorbed by the magnetic separator are discharged. The magnetic iron grade of the material reaches 30%. The material is ground in one stage using a ball mill until the passing rate of -200 mesh reaches 60%. The material is roughly separated by magnetic separation using a roughing magnetic separator, and the magnetic iron grade reaches 40%. The substances that cannot be magnetically separated are discharged. A hydrocyclone is used to classify the magnetically separated material. The material at the underflow port of this hydrocyclone is coarser, and the coarser material is returned to one end of the ball mill for regrinding. The passing rate of the overflow port for -200 mesh is 80%. The concentrated magnetic separation is cancelled, and the material is ground in the second stage. Pressure is applied when the material enters the fine grinding ball mill. This ball mill is equipped with its own classification system, and grinding and screening are carried out simultaneously. The material with a screening fineness of a passing rate of 90% for -400 mesh is subjected to magnetic separation again. Through three series-connected refining and slag-removing magnetic separators, superfine iron concentrate powder is obtained after magnetic separation. The final iron concentrate powder grade is 58%. Then, a disc filter is used for dehydration to reduce the moisture content to 14.8%, and the finished iron concentrate powder is obtained.

[0035] Comparative Example 2: In this comparative example, only one refining and slag-removing magnetic separation is carried out, and the specific steps are as follows: The mineral raw materials are preselected by magnetic separation. Water is added during magnetic separation, and the magnetic raw materials in the mineral raw materials are adsorbed by the magnetic separator. The substances that cannot be adsorbed by the magnetic separator are discharged. The magnetic iron grade of the material reaches 30%. The material is ground in one stage using a ball mill until the passing rate of -200 mesh reaches 60%. The material is roughly separated by magnetic separation using a roughing magnetic separator, and the magnetic iron grade reaches 40%. The substances that cannot be magnetically separated are discharged. A hydrocyclone is used to classify the magnetically separated material. The material at the underflow port of this hydrocyclone is coarser, and the coarser material is returned to one end of the ball mill for regrinding. The passing rate of the overflow port for -200 mesh is 80%. Concentrated magnetic separation is carried out to obtain a material with a magnetic iron grade of 50% and a moisture content of less than 30%. The material is ground in the second stage. Pressure is applied when the material enters the fine grinding ball mill. This ball mill is equipped with its own classification system, and grinding and screening are carried out simultaneously. The material with a screening fineness of a passing rate of 90% for -400 mesh is subjected to one refining and slag-removing magnetic separation. Superfine iron concentrate powder is obtained after magnetic separation. The final iron concentrate powder grade is 54%. Then, a disc filter is used for dehydration to reduce the moisture content to 11.3%, and the finished iron concentrate powder is obtained.

[0036] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not restrictive. Although the present invention has been described in detail with reference to the embodiments, those of ordinary skill in the art should understand that any modification or equivalent replacement of the technical solutions of the present invention does not depart from the spirit and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A grinding and separation process for ultrafine iron powder, characterized in that: Prepare the materials. The materials are mineral raw materials with a particle size of about 3 mm and a magnetic iron grade of more than 24%. The specific grinding and separation steps are as follows: S1: Conduct pre-selection magnetic separation on the mineral raw materials. The magnetic separator adsorbs the magnetic raw materials in the mineral raw materials to obtain material A, and the substances that cannot be adsorbed by the magnetic separator are discharged. S2: Grind the material A in one stage to obtain material B. S3: Conduct rough-selection magnetic separation on the material B. The magnetic separator adsorbs to obtain material C, and the materials that cannot be magnetically separated are discharged. S4: Conduct classification screening on the material C. Concentrate and magnetically separate the materials with a fineness of minus 200 mesh to obtain material D, and send the remaining materials coarser than minus 200 mesh to step S2 for repeated grinding.

2. The grinding and separation process of superfine iron powder according to claim 1, wherein: S5: Conduct two-stage grinding on the material D. Grinding and screening are carried out simultaneously. Screen the materials with a fineness lower than minus 400 mesh for re-magnetic separation, and obtain superfine iron concentrate after magnetic separation.

3. The grinding and separation process of ultrafine iron powder according to claim 1, characterized in that: The magnetic separation in step S1 and step S3 uses a magnetic separator.

4. The grinding and selection process of ultrafine iron powder according to claim 1, characterized in that: The magnetic separation in step S5 is three-stage refining and slag reduction magnetic separation.

5. The grinding and separation process of ultrafine iron powder according to claim 1, characterized in that: The grinding devices used in step S2 are all ball mills.

6. The grinding and separation process of ultrafine iron powder according to claim 1, characterized in that: The screening in step S4 uses a hydrocyclone, and the concentrate magnetic separation uses a magnetic separator.

7. The grinding and selection process of superfine iron powder according to claim 1, characterized in that: The grinding step in step S5 uses a ball mill, and the ball mill has the function of grinding and screening simultaneously.

8. The grinding and separation process of superfine iron powder according to claim 7, characterized in that: The superfine iron concentrate obtained in step S5 is dehydrated to make the water content lower than 10.5%. The disk filter is used in the dehydration step.