Dry grinding beneficiation method and system for refractory hematite

Abstract

The invention discloses a dry grinding beneficiation method and system for refractory hematite, and belongs to the technical field of beneficiation. The method comprises the following steps that iron ore is ground, hot air is supplemented for drying during grinding, and iron ore powder is obtained; performing particle size grading on the iron ore powder, and continuously grinding the iron ore powder with unqualified particle size until the particle size is qualified; performing magnetic separation on the iron ore powder with qualified particle size to obtain high-grade magnetic iron ore concentrate and non-magnetic ore, feeding the high-grade magnetic iron ore concentrate into an ore bin for storage, detecting the content of iron oxide in the non-magnetic ore, feeding the non-magnetic ore into a tailing dam for stockpiling if the non-magnetic ore has no recovery value, and performing magnetic roasting reduction if the non-magnetic ore has the recovery value; and the magnetized and roasted iron ore powder with magnetism is subjected to magnetic separation again, high-grade magnetic iron ore concentrate obtained after secondary magnetic separation is fed into the ore storage bin to be stored, and tailings without recovery value are fed into the tailings dam to be piled up.

Description

Technical Field

[0001] The invention belongs to the technical field of ore dressing, and in particular relates to a dry grinding ore dressing method and system for refractory hematite. Background Art

[0002] In the existing mineral processing technology, after the ore is crushed and screened, it enters the mill and is mixed with water, and then ground and dissociated. The ground ore is sorted by a hydrocyclone, and the ore with qualified particle size is sorted by a magnetic separator and sent to the concentrate dehydration workshop for concentration and filtration. If the iron grade of the tailings after the iron concentrate is selected by grinding and magnetic separation does not meet the required requirements, a ball mill will be added to grind the iron concentrate again and then magnetically separate it, or a flotation and reverse flotation process will be added to improve the iron grade.

[0003] The above-mentioned prior art adopts wet grinding technology, and the dehydration of hematite is difficult. In addition to conventional dehydration and filtration equipment, an additional round dryer is required to ensure that the moisture content in the iron concentrate meets the requirements of the pelletizing process. Therefore, the overall investment is large, the dehydration cost is high, and the tailings contain water. There is a risk of dam bursting when stored in the tailings dam. There are many precedents for such things. In summary, the current mineral processing technology has the problems of high equipment cost, high energy consumption and storage risk, and there is a lot of room for improvement.

[0004] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0005] The purpose of the present invention is to solve the problems of high equipment cost, high energy consumption and storage risk in the existing mineral processing technology, and to provide a dry grinding mineral processing method and system for refractory hematite.

[0006] 1. The first aspect of the present invention provides a dry grinding beneficiation method for refractory hematite, comprising the following steps:

[0007] Grinding the iron ore, adding hot air to dry it during grinding, to obtain iron ore powder;

[0008] The iron ore powder is graded into particle sizes, and the iron ore powder with unqualified particle sizes is further ground until the particle size reaches the qualified size;

[0009] The iron ore powder with qualified particle size is magnetically separated to obtain high-grade magnetic iron concentrate and non-magnetic ore. The high-grade magnetic iron concentrate is sent to the ore bin for storage, and the non-magnetic ore is tested for iron oxide content. If the non-magnetic ore has no recovery value, it is sent to the tailings dam for storage. If the non-magnetic ore has recovery value, it is magnetized and roasted for reduction. The magnetic iron ore powder after magnetization and roasting is magnetically separated again. The high-grade magnetic iron concentrate after the second magnetic separation is sent to the ore bin for storage, and the tailings without recovery value are sent to the tailings dam for storage.

[0010] In one embodiment of the present invention, the particle size classification includes using a dynamic powder classifier to classify the iron ore powder.

[0011] In one embodiment of the present invention, the particle size classification further includes: filtering the flue gas produced during the grinding process to remove dust with light density and low iron content, and the filtered solid particles are sent to the dynamic powder classifier for particle size classification.

[0012] In one embodiment of the present invention, the magnetization calcination uses hydrogen and carbon monoxide to reduce iron oxide to iron oxide.

[0013] In one embodiment of the present invention, the iron ore powder obtained after grinding is in powder form.

[0014] In one embodiment of the present invention, the moisture content of the ground iron ore powder does not exceed 0.5%.

[0015] In one embodiment of the present invention, the non-magnetic ore is deemed to have recycling value if the iron oxide content of the non-magnetic ore is greater than or equal to 15%, and is deemed to have no recycling value if the iron oxide content of the non-magnetic ore is less than 15%.

[0016] The second aspect of the present invention provides a dry grinding beneficiation system for refractory hematite, comprising the following equipment:

[0017] A hot air drying furnace, the air outlet of which is connected to the feed inlet of the dry ball mill, and is used to supply hot air to the dry ball mill;

[0018] Dry ball mill is used to grind iron ore and dry it during grinding to obtain iron ore powder;

[0019] Dynamic powder concentrator, used to classify iron ore powder by particle size;

[0020] The first magnetic separator is used to magnetically separate iron ore powder with qualified particle size to obtain high-grade magnetic iron concentrate and non-magnetic ore;

[0021] Magnetic roasting furnace, used for magnetic roasting of non-magnetic ores to reduce iron elements;

[0022] The second magnetic separator is used to magnetically separate the non-magnetic ore after magnetization and roasting to obtain high-grade magnetic iron concentrate and tailings after secondary magnetic separation;

[0023] Conveying system is used for transporting materials between equipment.

[0024] In one embodiment of the present invention, a static powder classifier is also included, and the feed port of the static powder classifier is connected to the dry ball mill, which is used to filter the flue gas generated by the dry ball mill to remove dust with light density and low iron content, and the filtered solid particles are fed into the dynamic powder classifier.

[0025] In one embodiment of the present invention, hydrogen and carbon monoxide are used in the magnetization roasting furnace to reduce iron oxide to ferroferric oxide.

[0026] Compared with the prior art, the technical effects achieved by the present invention are as follows:

[0027] 1. Dry ball mill is used to dry and grind iron ore to control the moisture content of the product, eliminating the dehydration process, flotation process and reverse flotation process in traditional technology, greatly reducing the investment cost. Moreover, since there is no flotation process, there is no need to add chemicals, and there is no pollution to the natural environment.

[0028] 2. The tailings produced by this process do not contain water, so there is no risk of dam breach in the tailings dam. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a flow chart of a dry grinding beneficiation method for refractory hematite according to one embodiment of the present invention;

[0030] Figure 2 It is a schematic structural diagram of a dry grinding beneficiation system for refractory hematite according to an embodiment of the present invention.

[0031] Description of main reference numerals:

[0032] 1. Dry ball mill; 21. Dynamic powder separator; 22. Static powder separator; 3. Dust collector; 41. First magnetic separator; 42. Second magnetic separator; 5. Magnetic roasting furnace; 6. Natural gas reformer; 71. Ore bin; 72. Tailings dam; 8. Crusher. DETAILED DESCRIPTION

[0033] Unless explicitly stated otherwise, throughout the specification and claims, the term “comprise” or variations such as “include” or “comprising”, etc., will be understood to include the stated elements or components but not to exclude other elements or components.

[0034] The technical solution of the present invention is described below by specific embodiments. It should be understood that one or more steps mentioned in the present invention do not exclude the existence of other methods and steps before and after the combination step, or other methods and steps can be inserted between these explicitly mentioned steps. It should also be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. Unless otherwise specified, the numbering of each method step is only for the purpose of identifying each method step, and does not limit the order of arrangement of each method or limit the scope of implementation of the present invention. The change or adjustment of the relative relationship thereof can also be regarded as the scope of implementation of the present invention without substantial changes in the technical content.

[0035] The sources of the raw materials and instruments used in the examples are not particularly limited and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0036] like Figure 1 As shown, the dry grinding beneficiation method of refractory hematite according to a preferred embodiment of the present invention includes the following steps.

[0037] The iron ore is ground and hot air is added to dry the iron ore during grinding to obtain iron ore powder. The water content of the iron ore before grinding is usually more than 3%. After grinding and drying, a powdery iron ore powder with a water content of less than 0.5% is obtained.

[0038] The iron ore powder is graded by particle size. The particle size classification process requires the use of two types of equipment, one is the static powder classifier, and the other is the dynamic powder classifier. When the iron concentrate is produced, a large amount of flue gas will also be generated. The flue gas is transported to the static powder classifier to remove dust with light density and low iron content. The remaining solid particles are sent to the dynamic powder classifier; and the directly produced iron ore powder is also sent to the dynamic powder classifier. The dynamic powder classifier is used for particle size classification. The iron ore powder with unqualified particle size continues to be ground until the particle size is qualified. Particles with a size of more than 400 mesh can be considered qualified.

[0039] Iron ore powder with qualified particle size is subjected to magnetic separation to obtain high-grade magnetic iron concentrate and non-magnetic ore. Magnetic separation is a method of existing technology. It is a method of screening different minerals by using the difference in magnetic permeability of minerals. Minerals with high magnetic permeability will be sucked up by the magnetic disk, while minerals with low magnetic permeability will be removed. High-grade magnetic iron concentrate is sent to the ore bin for storage. Non-magnetic ore is tested for iron oxide content. If the non-magnetic ore has no recovery value, it is sent to the tailings dam for storage. If the non-magnetic ore has recovery value, it is magnetized and roasted for reduction. After magnetized, roasted and reduced, the magnetic iron ore powder is magnetically separated again. The high-grade magnetic iron concentrate after the second magnetic separation is sent to the ore bin for storage, and the tailings without recovery value are sent to the tailings dam for storage. High-grade magnetic iron concentrate refers to minerals with a high iron content, and usually a content of more than 60% is considered high grade. The obtained high-grade magnetic iron concentrate can be directly used in the ball making process. Non-magnetic ores need to be tested for iron oxide content to determine whether they have recycling value. Non-magnetic ores with an iron oxide content greater than or equal to 15% are considered to have recycling value, and those with a content less than 15% are considered to have no recycling value. If they have recycling value, they are sent to a magnetizing roasting furnace, where hydrogen and carbon monoxide are used to reduce the iron oxide to ferroferric oxide. In this way, the valuable part of the iron ore will be used as much as possible, avoiding waste of resources.

[0040] This method is a dry method, which is different from the traditional wet method. Because the tailings do not contain water, there is no risk of dam collapse in the tailings dam. In addition, the process omits dehydration, flotation and other processes, which can also reduce equipment investment.

[0041] As an implementation of the above method, the present invention discloses an embodiment of a dry grinding beneficiation system for refractory hematite, which corresponds to the above method embodiment. Figure 2 The dry grinding beneficiation system for refractory hematite of this embodiment includes the following equipment: a hot air drying furnace, a dry ball mill 1, a static powder separator 22, a dust collector 3, a dynamic powder separator 21, a first magnetic separator 41, a second magnetic separator 42, a magnetic roasting furnace 5, a natural gas reformer 6, a ore bin 71 and a tailings dam 72.

[0042] The air outlet of the hot air drying furnace is connected to the feed port of the dry ball mill 1, and is used to supply hot air to the dry ball mill 1. The dry ball mill 1 is used to grind iron ore and dry it on the grinding stone to obtain iron ore powder with a water content of less than 0.5%. The iron ore is crushed by the crusher 8 and then transported to the dry ball mill 1. When the iron ore powder is obtained, a large amount of smoke and dust will also be generated. This part of the smoke and dust is transported to the static powder separator 22 through a pipeline for filtration to remove dust with light density and low iron content, and obtain solid particles. The dust is transported to the dust collector 3 through a pipeline for treatment. The obtained solid particles are also part of the iron ore powder. Subsequently, the solid particles are transported to the dynamic powder separator 21 by the conveying system, and the iron ore powder produced by the dry ball mill 1 is also transported to the dynamic powder separator 21 through the conveying system, and the particle size classification is performed in the dynamic powder separator 21. The iron ore powder with qualified particle size is transported to the first magnetic separator 41 through the conveying system. The iron ore powder with unqualified particle size is transported back to the dry ball mill 1 through the conveying system and ground again.

[0043] After magnetic separation in the first magnetic separator 41, high-grade magnetic iron concentrate and non-magnetic ore are obtained. The high-grade magnetic iron concentrate can be directly sent to the ore bin 71 for storage or subsequent ball making process. The non-magnetic ore is tested for iron oxide content. If it has recovery value, it is transported to the magnetic roasting furnace 5 through the conveying system; if it has no value, it is sent to the tailings dam 72 for storage through the conveying system. If the iron oxide content of the non-magnetic ore is greater than or equal to 15%, it is considered to have recovery value, and if it is less than 15%, it is considered to have no recovery value.

[0044] Hydrogen and carbon monoxide can be prepared by the natural gas reformer 6. The specific process is that methane and oxygen are incompletely burned to produce carbon monoxide and hydrogen, which belongs to the prior art. Hydrogen and carbon monoxide will be transported to the magnetic roasting furnace 5 through a pipeline to reduce iron oxide to iron oxide. Subsequently, the material output from the magnetic roasting furnace 5 is transported to the second magnetic separator 42 through a conveying system, and magnetic separation is performed again. The high-grade magnetic iron concentrate after the secondary magnetic separation is also transported to the ore bin 71 through the conveying system, and the tailings without recovery value after the secondary magnetic separation are directly sent to the tailings dam 72 through the conveying system.

[0045] The conveying system includes multiple devices for transporting materials, such as air chutes, elevators, screw conveyors, etc., which are used to transport materials between the above-mentioned equipment and are adaptively selected and matched based on usage needs.

[0046] The whole system utilizes a dry ball mill 1 to dry and grind the iron ore, thereby controlling the moisture content of the product and eliminating the dehydration process, flotation process, and reverse flotation process in the traditional process, thus greatly reducing the investment cost. In addition, since there is no flotation process, there is no need to add chemicals, and there is no pollution to the natural environment.

[0047] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. A dry grinding beneficiation method for refractory hematite, characterized in that: The following steps are involved: Grinding the iron ore, adding hot air to dry it during grinding, to obtain iron ore powder; The iron ore powder is graded into particle sizes, and the iron ore powder with unqualified particle sizes is further ground until the particle size reaches the qualified size; The iron ore powder with qualified particle size is magnetically separated to obtain high-grade magnetic iron concentrate and non-magnetic ore. The high-grade magnetic iron concentrate is sent to the ore bin for storage, and the non-magnetic ore is tested for iron oxide content. If the non-magnetic ore has no recovery value, it is sent to the tailings dam for storage. If the non-magnetic ore has recovery value, it is magnetized and roasted for reduction. The magnetic iron ore powder after magnetization and roasting is magnetically separated again. The high-grade magnetic iron concentrate after the second magnetic separation is sent to the ore bin for storage, and the tailings without recovery value are sent to the tailings dam for storage.

2. The dry grinding beneficiation method for refractory hematite according to claim 1, characterized in that: The particle size classification includes using a dynamic powder classifier to classify the iron ore powder by particle size.

3. The dry grinding beneficiation method for refractory hematite according to claim 2, characterized in that: The particle size classification also includes: filtering the flue gas produced during the grinding process to remove dust with light density and low iron content, and the filtered solid particles are sent to the dynamic powder selector for particle size classification.

4. The dry grinding beneficiation method for refractory hematite according to claim 1, characterized in that: The magnetization roasting reduces the iron oxide to ferroferric oxide using hydrogen and carbon monoxide.

5. The dry grinding beneficiation method for refractory hematite according to claim 1, characterized in that: The iron ore powder obtained after grinding is in powder form.

6. The dry grinding beneficiation method for refractory hematite according to claim 1, characterized in that: The moisture content of the iron ore powder obtained by grinding does not exceed 0.5%.

7. The dry grinding beneficiation method for refractory hematite according to claim 1, characterized in that: The non-magnetic ore is deemed to have recycling value if the iron oxide content of the non-magnetic ore is greater than or equal to 15%, and is deemed to have no recycling value if the iron oxide content of the non-magnetic ore is less than 15%.

8. A dry grinding beneficiation system for refractory hematite, characterized in that: The equipment includes: A hot air drying furnace, the air outlet of which is connected to the feed inlet of the dry ball mill, and is used to supply hot air to the dry ball mill; Dry ball mill is used to grind iron ore and dry it during grinding to obtain iron ore powder; Dynamic powder concentrator, used to classify iron ore powder by particle size; The first magnetic separator is used to magnetically separate iron ore powder with qualified particle size to obtain high-grade magnetic iron concentrate and non-magnetic ore; Magnetic roasting furnace, used for magnetic roasting of non-magnetic ores to reduce iron elements; The second magnetic separator is used to magnetically separate the non-magnetic ore after magnetization and roasting to obtain high-grade magnetic iron concentrate and tailings after secondary magnetic separation; Conveying system is used for transporting materials between equipment.

9. The dry grinding beneficiation system for refractory hematite according to claim 8, characterized in that: It also includes a static powder classifier, the feed port of which is connected to the dry ball mill and is used to filter the flue gas generated by the dry ball mill to remove dust with light density and low iron content, and the filtered solid particles are fed into the dynamic powder classifier.

10. The dry grinding beneficiation system for refractory hematite according to claim 8, characterized in that: The magnetization roasting furnace uses hydrogen and carbon monoxide to reduce iron oxide to ferroferric oxide.

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