Comprehensive utilization method of sandstone aggregate waste powder

Abstract

The invention provides a comprehensive utilization method of sandstone aggregate waste powder, belongs to the technical field of processing and purification of non-metal ores, and solves the defect that the sandstone aggregate waste powder cannot be economically and environmentally friendly used for preparing various non-metal ore products in the prior art. The method comprises the steps that S1, sandstone aggregate waste powder is scrubbed and graded, and coarse sand and fine sand are obtained; s2, performing medium magnetic pre-selection on the fine sand to obtain pre-selected fine sand and a cement raw material; s3, the pre-selected fine sand is subjected to strong magnetic separation, and separated fine sand and cement raw materials are obtained; s4, grading the sorted fine sand to obtain primary kaolin and feldspar products; and S5, performing high-gradient strong magnetic separation on the primary kaolin to obtain a kaolin product and a cement raw material. The comprehensive utilization method of the sandstone aggregate waste powder provided by the invention has the advantage that the sandstone aggregate waste powder can be utilized economically and environmentally to prepare various non-metal mineral products.

Description

Technical Field

[0001] The present invention belongs to the technical field of building material processing, and specifically relates to a processing method for physically processing waste powder left over from sand and gravel aggregate production, especially obtaining non-metallic mineral products such as ceramic raw materials and cement raw materials, and more particularly relates to a comprehensive utilization method of sand and gravel aggregate waste powder. Background Art

[0002] Ceramics and cement are two important non-metallic mineral products used as building materials. Their raw material sources overlap somewhat (such as clay and limestone), but they also have their own specific mineral requirements, as detailed below:

[0003] 1. Source of ceramic raw materials

[0004] Ceramic raw materials are mainly divided into three categories: plastic raw materials (clay), barren raw materials (quartz), and flux raw materials (feldspar). The specific sources are as follows:

[0005] (1) Plastic raw materials (provide plasticity and facilitate molding)

[0006] -Kaolin (porcelain clay): The main component is kaolinite (Al2O3·2SiO2·2H2O), used in high-end ceramics (such as porcelain).

[0007] -Bentonite: Contains montmorillonite, which can improve the strength of the green body.

[0008] -Ball clay: contains organic matter, has good plasticity, and is used for fine ceramics.

[0009] -Ordinary clay: used for ordinary bricks, tiles, pottery, etc.

[0010] (2) Lean raw materials (reduce shrinkage and increase strength)

[0011] -Quartz (SiO2): provides silicon, enhances the hardness of the blank and reduces drying shrinkage.

[0012] -Calcined alumina (Al2O3): used in high-performance ceramics (such as electronic ceramics).

[0013] (3) Flux raw materials (to reduce firing temperature)

[0014] -Feldspar (potassium feldspar, sodium feldspar): melts at high temperatures and promotes vitrification.

[0015] -Talc (MgO·SiO2): used in magnesia ceramics.

[0016] -Calcium carbonate (CaCO3): used in some low-temperature ceramics.

[0017] (4) Other auxiliary raw materials

[0018] - Pigments (iron oxide, cobalt oxide, etc.): used for glaze coloring.

[0019] - Bone ash (calcium phosphate): used for bone china.

[0020] 2. Sources of cement raw materials

[0021] The main component of cement is silicate. Its core raw materials include: lime raw materials, clay raw materials, and correction raw materials, as follows:

[0022] (1) Main raw materials (accounting for more than 90%)

[0023] - Limestone (CaCO3): provides calcium oxide (CaO), accounting for 70%-80% of cement raw materials.

[0024] - Clay (SiO2+Al2O3): Provides silicon and aluminum components, accounting for 15%-20%.

[0025] - Iron ore (Fe2O3) or pyrite slag: adjusts the iron content and promotes clinker formation.

[0026] (2) Correction of raw materials (adjustment of ingredients)

[0027] -Silica correction material (sandstone, diatomaceous earth): supplements the lack of SiO2.

[0028] -Aluminum correction material (bauxite, coal gangue): supplement the deficiency of Al2O3.

[0029] - Iron correction material (sulfuric acid slag, iron ore powder): supplement the lack of Fe2O3.

[0030] (3) Industrial waste residue alternative raw materials (environmental protection trend)

[0031] - Fly ash (waste from thermal power plants): replaces part of the clay.

[0032] - Slag (steel plant waste): replaces part of the clinker.

[0033] -Carbide slag (chemical waste): replaces part of limestone.

[0034] As mentioned above, if the waste materials of construction materials mainly contain kaolin, quartz, feldspar, limestone, clay, iron ore, etc., you can consider using chemical or physical or a combination of both processes to separate them and make them into ceramic raw materials or cement raw materials.

[0035] At present, in the building materials manufacturing industry, granite deposit resources are basically used to produce sand and gravel aggregates. During production, some or a small amount of waste powder is often generated. These waste powders are either stored or discarded. This is not only uneconomical, but also poses the risk of environmental problems.

[0036] Therefore, there is an urgent need to provide a comprehensive utilization method for the sand and gravel aggregate waste powder generated by the building materials manufacturing industry in an economical and environmentally friendly manner. Summary of the Invention

[0037] In view of this, the present invention provides a comprehensive utilization method of sand and gravel aggregate waste powder to solve the technical problem in the existing technology that it is impossible to use sand and gravel aggregate waste powder in an economical and environmentally friendly way to prepare various non-metallic mineral products, especially ceramic raw materials and cement raw materials.

[0038] The technical solution adopted in the present invention is:

[0039] The present invention provides a comprehensive utilization method of waste sand and gravel aggregate powder, comprising: S1, scrubbing and classifying the waste sand and gravel aggregate powder to obtain coarse sand and fine sand; S2, performing medium magnetic preselection on the fine sand to obtain preselected fine sand and cement raw materials; S3, performing strong magnetic separation on the preselected fine sand to obtain sorted fine sand and cement raw materials; S4, classifying the sorted fine sand to obtain primary kaolin and feldspar products; S5, performing high-gradient strong magnetic separation on the primary kaolin to obtain kaolin products and cement raw materials.

[0040] Furthermore, in step S1, mechanical grinding and strong stirring are used to scrub the sand and gravel aggregate waste powder so that the minerals therein are fully dissociated into monomers, and then the waste powder is screened and separated by a linear single-layer vibrating screen to classify the minerals.

[0041] Furthermore, the screen of the linear single-layer vibrating screen is set to 40 mesh, the particle size of the coarse sand is +40 mesh, and the particle size of the fine sand is -40 mesh. Step S1 also includes screening and separating the coarse sand to obtain fine sand for road construction and coarse sand for construction.

[0042] Furthermore, in step S2, a medium magnetic field drum permanent magnetic separator or a vertical ring medium magnetic separator is used and the separation magnetic field is 400mT to 500mT to perform wet magnetic separation on the fine sand.

[0043] Furthermore, in step S3, two wet magnetic separations are performed on the preselected fine sand using a two-stage high-magnetic field vertical ring or flat ring high gradient magnetic separator with a separation magnetic field of 1000mT to 1500mT.

[0044] Furthermore, in step S4, a hydrocyclone or a spiral classifier is used to separate and classify the selected fine sand to obtain primary kaolin of -325 to 0 mesh and feldspar products of -40 to +325 mesh.

[0045] Furthermore, in step S5, a high gradient strong magnetic separator is used and two stages of magnetic separation are continuously performed under the condition of separation magnetic field of 1450mT to 2000mT, thereby obtaining kaolin products and cement raw materials.

[0046] Furthermore, the magnetic medium of the high gradient high intensity magnetic separator is made of 430# magnetic conductive stainless steel and the mesh size of the drawn steel mesh is set to 4×8 mm and 2×4 mm.

[0047] Furthermore, the SiO2 grade of the sand and gravel aggregate waste powder is 70%-80%, the Al2O3 grade is 10%-15%, and the Fe2O3 grade is 1%-1.5%.

[0048] Furthermore, the yield of the cement raw material obtained in step S2 is 5%-6%, wherein the SiO2 grade is 55%-60% and the SiO2 distribution rate is 3%-4%, the Fe2O3 grade is 5%-6% and the Fe2O3 distribution rate is 20%-25%, the yield of the feldspar product obtained in step S4 is 25%-35%, wherein the SiO2 grade is 75%-80% and the SiO2 distribution rate is 0.01%-0.1%, the Fe2O3 grade is 15%-20% and the Fe2O3 distribution rate is 1%-1.5%, and ...5 is 25%-35%, wherein the SiO2 grade is 75%-80% and the SiO2 distribution rate is 0.01%-0.1%, the Fe2O3 grade is 15%-20% and the Fe2O3 distribution rate is 1%-1.5%, and the yield of the feldspar product obtained in step S6 is 25%-35%, wherein the SiO2 grade is 75%-80% and the SiO2 distribution rate is 0.01%-0.1%, the Fe2O3 grade is 15%-20% and the Fe2O3 distribution rate is 1%-1.5%, and the yield of the feldspar product obtained in step S7 is 25%-35%, wherein the SiO2 grade is 75%-80% and the SiO2 distribution rate is 0.01%-0.1%, the Fe2O3 grade is 15%-20 The yield of the kaolin product obtained in step S5 is 10%-20%, and the Al2O3 grade is 25%-30%, and the Al2O3 distribution rate is 20%-25%, the Fe2O3 grade is 2%-3%, and the Fe2O3 distribution rate is 15%-20%. The yield of the cement raw material obtained in step S5 is 0.05%-0.2%, and the SiO2 grade is 40%-45%, and the SiO2 distribution rate is 0.01%-0.1%, the Fe2O3 grade is 15%-20%, and the Fe2O3 distribution rate is 1%-1.5%.

[0049] In summary, the beneficial effects of the present invention are as follows:

[0050] The comprehensive utilization method of sand and gravel aggregate waste powder provided by the present invention uses a fully physical method to process sand and gravel aggregate waste powder into kaolin and feldspar mineral products that can be used as ceramic raw materials. Not only does it not use chemical treatment methods such as flotation or pickling, so that the entire production process is low-cost and there is no environmental pollution problem, but also, during the process of using this method, coarse sand can be used as road sand and construction sand, and various iron-containing sands can be used as cement raw materials for cement plants. Therefore, all products obtained during the implementation of this method are comprehensively utilized, thereby generating very high economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work, and these are all within the scope of protection of the present invention.

[0052] Figure 1This is a process flow chart of the comprehensive utilization method of sand and gravel aggregate waste powder provided by the present invention;

[0053] Figure 2 corresponds to Figure 1 A numerical quality flow chart of the technical implementation of the comprehensive utilization method provided by the present invention. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. It should be noted that, in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In the description of the present invention, it should be understood that the orientation or position relationship indicated by the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like is based on the orientation or position relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further limitations, elements defined by the phrase "comprising..." do not preclude the presence of additional identical elements in the process, method, article, or apparatus comprising the elements. The embodiments of the present invention and the features thereof may be combined with each other if there is no conflict, and all are within the scope of protection of the present invention.

[0055] refer to Figure 1 and Figure 2As an object of the present invention, a method for the comprehensive utilization of waste sand and gravel aggregate powder is provided. Sand and gravel aggregate is a general term for materials such as sand, pebbles, crushed stone, blocks, and rubble stones used in water conservancy projects. It is also the most widely used, indispensable, and irreplaceable basic material in the construction of infrastructure projects such as buildings, roads, and bridges. Specifically, sand and gravel aggregate plays a skeleton and filler role in concrete, stabilizing volume and transmitting stress. The comprehensive utilization method provided by the present invention includes the following steps: S1. Scrubbing and classifying the waste sand and gravel aggregate powder to obtain coarse sand and fine sand. As described above, the waste sand and gravel aggregate powder can be the accumulation of waste powder inevitably generated during the process of mining and utilizing primary granite, weathered granite, basalt, and other mineral deposits to prepare sand and gravel aggregate, and the waste sand and gravel aggregate powder contains minerals such as feldspar and kaolin. When granite powder obtained by mining, for example, primary granite deposits is used to produce sand and gravel aggregates for road construction, the granite powder can generally be converted into, for example, qualified sand and gravel aggregates for road construction through a four-step process of "pretreatment - bonding and forming - strengthening - grading optimization". The waste generated and accumulated during the conversion of the granite powder, i.e., the preparation of the sand and gravel aggregates, corresponds to the waste sand and gravel aggregate powder of the present invention. Among them, classification and impurity removal are required in the "pretreatment" step. During the classification and impurity removal, screening is required: using a vibrating screen or an airflow separator to remove clay with too fine a particle size (<0.075 mm), retaining coarse particles of 0.075-5 mm as the sand and gravel aggregate base material, and scrubbing: using a spiral sand washer or a hydrocyclone to remove surface clay minerals (such as kaolin) to improve the cleanliness of the aggregate. It can be seen from this that the mesh size range of the coarse particles corresponding to the sieve is roughly 3-200. Therefore, if the mesh size of the following linear single-layer vibrating screen is set to 40 mesh, the desired coarse sand and fine sand can be obtained. The waste sand and gravel aggregate powder generated in the aggregate production process contains the above-mentioned coarse particles and clay minerals such as kaolin that are removed to improve the cleanliness of the aggregate. Therefore, the waste sand and gravel aggregate powder that is regarded as waste in the prior art has resource utilization value, especially if it can be used to prepare ceramic raw materials and cement raw materials at the same time, the economic value is particularly prominent. In addition, the other steps and technical details of the above four-step method are known to those skilled in the art and will not be repeated here. S2, medium magnetic pre-selection of fine sand to obtain pre-selected fine sand and cement raw materials; S3, strong magnetic separation of pre-selected fine sand to obtain sorted fine sand and cement raw materials; S4, classification of sorted fine sand to obtain primary kaolin and feldspar products; S5, high gradient strong magnetic separation of primary kaolin to obtain kaolin products and cement raw materials.

[0056] In this way, the comprehensive utilization method of sand and gravel aggregate waste powder provided by the present invention adopts a fully physical processing method to process the sand and gravel aggregate waste powder that is regarded as having no economic value in the prior art into kaolin and feldspar mineral products that can be used as ceramic raw materials. Not only does it not adopt chemical treatment methods such as flotation or pickling, so that the entire production process has low cost and no environmental pollution problems. Moreover, in the process of adopting the method, in addition to the feldspar products and kaolin products that are obtained as ceramic raw materials as the main purpose, coarse sand can be used as road sand and construction sand, and various iron-containing sands can also be used as cement raw materials for cement plants. Therefore, all non-metallic mineral products obtained during the implementation of this method are comprehensively utilized, thereby generating very high economic benefits without any environmental pollution problems.

[0057] Please refer to reference 1 and Figure 2 Specifically, in step S1, mechanical grinding is performed using, for example, a Raymond mill. The Raymond mill can process minerals with a Mohs hardness of 7 or less and is suitable for grinding high-hardness components such as quartz and feldspar. It can grind the waste sand and gravel aggregate powder into a fine powder, achieving preliminary dissociation of the minerals. Furthermore, a stirred mill or ball mill is used for strong stirring. Through the high-intensity collision and friction of the steel balls or stirring medium of the stirred mill or ball mill, combined with the stirred mill or wet ball milling process, the separation degree of the kaolin and quartz mixture in the waste sand and gravel aggregate powder can be increased, further dissociating the mineral particles. The above-mentioned mechanical grinding and strong stirring can jointly play a role in scrubbing and removing impurities. In addition, a spiral or bucket wheel stone washer can be selected to scrub and remove impurities, depending on the large-scale or small-scale processing volume of the waste sand and gravel aggregate powder. With the above-mentioned mechanical grinding, strong stirring, and scrubbing of the waste sand and gravel aggregate powder, the minerals therein can be fully dissociated into monomers, and then screened and separated by a linear single-layer vibrating screen to classify the minerals. Therefore, step S1 can be used to specifically separate the waste sand and gravel aggregate powder into two grades of coarse sand and fine sand.

[0058] Please refer to Figure 1 and Figure 2 Preferably, the screen of the linear single-layer vibrating screen is set to 40 mesh, the particle size of the coarse sand is +40 mesh, and the particle size of the fine sand is -40 mesh. Step S1 also includes screening and separating the coarse sand through a linear single-layer vibrating screen or a circular vibrating screen to obtain fine sand for road construction and coarse sand for construction. In this way, the fine sand is used as the raw material for obtaining feldspar and kaolin products in the next step, and the coarse sand is used as sand for road construction and construction, so the utilization rate of waste sand and gravel aggregate powder is high.

[0059] Please refer to Figure 1 and Figure 2Specifically, in step S2, a medium magnetic field drum permanent magnetic separator or a vertical ring medium magnetic separator is used and the separation magnetic field is 400mT to 500mT to perform wet magnetic separation on the fine sand to implement medium magnetic pre-selection, thereby achieving the purpose of removing the mechanically ferromagnetic iron entrained in the -40 mesh fine sand as a raw material and the ferromagnetic iron minerals such as ferroferric oxide (Fe3O4) in the raw material itself, so that the mechanically ferromagnetic iron and ferromagnetic iron minerals will not be wasted but can be used as cement raw materials, thereby improving resource utilization.

[0060] Please refer to Figure 1 and Figure 2 Specifically, in step S3, two sections of strong magnetic field vertical ring or flat ring high gradient magnetic separators are used and the separation magnetic field is 1000mT to 1500mT to perform two wet magnetic separations on the preselected fine sand to implement strong magnetic separation. Cement raw materials can be obtained through the two wet magnetic separations, so as to remove iron oxide (Fe2O3) and titanium minerals (TiO2) in the preselected fine sand obtained from the previous process, so as to achieve the purpose of further purifying the preselected fine sand and improving the whiteness of the product.

[0061] Please refer to Figure 1 and Figure 2 Specifically, in step S4, a hydrocyclone or a spiral classifier is used to separate and classify the fine sand used as the raw material after the treatment in the above step S3, and obtain primary kaolin of -325 to 0 mesh and feldspar products of -40 to +325 mesh. In the embodiment of the present invention, the feldspar product is specifically potassium feldspar sand, which can be used as a raw material for preparing ceramics.

[0062] Please refer to Figure 1 and Figure 2 Specifically, in step S5, a high-gradient strong magnetic separator is used and the separation magnetic field is continuously carried out in two stages under the conditions of 1450mT to 2000mT. This can achieve the purpose of removing micron-sized iron oxide and titanium coloring minerals, thereby magnetically separating and obtaining kaolin products and cement raw materials containing micron-sized iron oxide and titanium coloring minerals. Since the kaolin products are obtained through the above-mentioned multi-stage magnetic separation, they have very high purity and are particularly suitable as raw materials for preparing ceramics.

[0063] Specifically, the high-gradient magnetic separator's magnetic medium is made of 430# magnetically conductive stainless steel, and the expanded metal mesh has mesh sizes of 4×8 and 2×4. This design of the high-gradient magnetic separator's magnetic medium and expanded metal mesh is particularly suitable for the continuous two-stage removal of micron-sized iron oxide and titanium coloring minerals from sand and gravel aggregate waste powder.

[0064] To distinguish the above description, the cement raw material obtained in step S2 can be called the first cement raw material, the cement raw materials obtained by the two wet magnetic separations in step S3 can be called the second cement raw material and the third cement raw material, and the cement raw material obtained in step S5 can be called the fourth cement raw material. In comparison, the iron content of the second cement raw material and the third cement raw material is lower than that of the first cement raw material. The first cement raw material is particularly suitable as a high-iron cement raw material, and the iron content of the fourth cement raw material is higher than the iron content of any of the above-mentioned cement raw materials, and thus is particularly suitable as a cement raw material with a higher iron content.

[0065] Please refer to Figure 2 , Figure 2 A flow chart showing the data quality of a semi-industrial test conducted on waste sand and gravel aggregate powder in Guangdong using the technical solution of the present invention. Specifically, in this actual test application, the waste sand and gravel aggregate powder had a SiO2 grade of 70%-80%, an Al2O3 grade of 10%-15%, and a Fe2O3 grade of 1%-1.5%. This demonstrates that the method provided by the present invention, utilizing a fully physical processing method, can fully target the grade characteristics of the three components in the waste sand and gravel aggregate powder to produce feldspar and kaolin for use as ceramic raw materials, while also utilizing the coarse sand as sand for road and construction use, as well as various iron-containing cement raw materials.

[0066] Specifically, the yield of the cement raw material obtained in step S2 is 5%-6%, wherein the SiO2 grade is 55%-60% and the SiO2 distribution rate is 3%-4%, the Fe2O3 grade is 5%-6% and the Fe2O3 distribution rate is 20%-25%, the yield of the feldspar product obtained in step S4 is 25%-35%, wherein the SiO2 grade is 75%-80% and the SiO2 distribution rate is 0.01%-0.1%, the Fe2O3 grade is 15%-20% and the Fe2O3 distribution rate is 1%-1.5%, and ...5 is 25%-35%, wherein the SiO2 grade is 75%-80% and the SiO2 distribution rate is 0.01%-0.1%, the Fe2O3 grade is 15%-20% and the Fe2O3 distribution rate is 1%-1.5%, and the yield of the feldspar product obtained in step S6 is 25%-35%, wherein the SiO2 grade is 75%-80% and the SiO2 distribution rate is 0.01%-0.1%, the Fe2O3 grade is 15%-20% and the Fe2O3 distribution rate is 1%-1.5%, and the yield of the feldspar product obtained in step S7 is 25%-35%, wherein the SiO2 grade is 75%-80% and the SiO2 distribution rate is 0.01%-0.1%, the Fe2O3 grade is 15%-20 The yield of the kaolin product obtained in step S5 is 10%-20%, and the Al2O3 grade is 25%-30%, and the Al2O3 distribution rate is 20%-25%, the Fe2O3 grade is 2%-3%, and the Fe2O3 distribution rate is 15%-20%. The yield of the cement raw material obtained in step S5 is 0.05%-0.2%, and the SiO2 grade is 40%-45%, and the SiO2 distribution rate is 0.01%-0.1%, the Fe2O3 grade is 15%-20%, and the Fe2O3 distribution rate is 1%-1.5%. It can be seen that by adopting the method provided by the present invention, it is particularly possible to comprehensively utilize sand and gravel aggregate waste powder to obtain non-metallic mineral products including, in particular, ceramic raw materials and cement raw materials with a grade and distribution rate that meet the requirements. The yields of feldspar products and kaolin finished products reach 25%-35% and 10%-20%, respectively. Therefore, the sand and gravel aggregate waste powder that is conventionally discarded as waste is effectively utilized to prepare ceramic raw materials, which has high economic benefits. The Fe2O3 grade of the cement raw materials obtained in steps S2 and S5 is greater than 4%, which can especially meet the requirements for cement raw materials with specific high requirements for iron content.

[0067] In addition, when the two wet magnetic separations of step S3 are adopted, the yield of the cement raw material obtained by the first wet magnetic separation is 4%-5%, and the SiO2 grade is 55%-60%, and the SiO2 distribution rate is 3%-4%, the Fe2O3 grade is 4%-5%, and the Fe2O3 distribution rate is 15%-20%. The yield of the cement raw material obtained by the second wet magnetic separation is 2%-3%, and the SiO2 grade is 60%-65%, and the SiO2 distribution rate is 2%-3%, the Fe2O3 grade is 2%-3%, and the Fe2O3 distribution rate is 5%-6%. It can be seen that through two wet magnetic separations, the cement raw material obtained by the second wet magnetic separation has a higher SiO2 grade and a lower iron content than the cement raw material obtained by the first wet magnetic separation, so that it is more suitable for preparing cement with relatively higher strength and relatively lower durability.

[0068] from Figure 2The test data obtained in the present invention demonstrate that the method can be used to obtain non-metallic mineral products for various industrial applications, such as road construction sand, construction sand, feldspar products, and kaolin products. The remaining iron-containing materials can also be used as cement raw materials in cement plants. This allows for comprehensive utilization of all processed products without causing environmental pollution.

[0069] according to Figure 2 Based on the above description, the comprehensive utilization method provided by the present invention is applied to a specific embodiment and is summarized as follows:

[0070] 1. The waste sand and gravel aggregate powder is mechanically ground and vigorously stirred to fully dissociate the quartz, feldspar, kaolin and other minerals in the raw materials. It is then classified by sieving to obtain coarse sand and fine sand. The coarse sand can be used as building sand and construction sand, while the fine sand is used as raw material for the next step of producing feldspar and kaolin products.

[0071] 2. The fine sand obtained after scrubbing and classification is then subjected to multi-stage magnetic separation to remove iron and physically separate and purify the colored magnetic materials in the material. Subsequently, hydraulic classification is used to physically separate the products based on the particle size differences between feldspar and kaolin.

[0072] 3. Throughout the entire production process of feldspar and kaolin products, only magnetic separation equipment with different magnetic field intensities and gradients is used to remove coloring impurities such as iron and titanium from the semi-finished products of each operation, without using chemical treatment methods such as flotation or pickling. This makes the entire production process low-cost and eliminates environmental pollution issues.

[0073] Therefore, the comprehensive utilization method of sand and gravel aggregate waste powder provided by the present invention can not only use sand and gravel aggregate waste powder to prepare ceramic raw materials in an economical and environmentally friendly manner, but also obtain sand for road construction, construction sand and cement raw materials, so that all processed products are comprehensively utilized, thereby achieving high resource utilization.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A comprehensive utilization method of sand and gravel aggregate waste powder, characterized in that: The steps include: S1. Scrub and classify waste sand and gravel aggregate powder to obtain coarse sand and fine sand; S2. performing medium magnetic preselection on the fine sand to obtain preselected fine sand and cement raw materials; S3. Performing strong magnetic separation on the pre-selected fine sand to obtain selected fine sand and cement raw materials; S4, classifying the sorted fine sand to obtain primary kaolin and feldspar products; S5. Performing high-gradient strong magnetic separation on the primary kaolin to obtain kaolin products and cement raw materials.

2. The comprehensive utilization method according to claim 1, characterized in that: In step S1, mechanical grinding and strong stirring are used to scrub the sand and gravel aggregate waste powder so that the minerals therein are fully dissociated into monomers, and then the waste powder is screened and separated by a linear single-layer vibrating screen to classify the minerals.

3. The comprehensive utilization method according to claim 2, characterized in that: The screen of the linear single-layer vibrating screen is set to 40 mesh, the particle size of the coarse sand is +40 mesh, and the particle size of the fine sand is -40 mesh. The step S1 also includes screening and separating the coarse sand to obtain fine sand for road construction and coarse sand for construction.

4. The comprehensive utilization method according to claim 1, characterized in that: In step S2, a medium magnetic field drum permanent magnetic separator or a vertical ring medium magnetic separator is used to perform wet magnetic separation on the fine sand under the condition that the separation magnetic field is 400mT to 500mT.

5. The comprehensive utilization method according to claim 1, characterized in that: In step S3, the preselected fine sand is subjected to two wet magnetic separations using a two-stage high-magnetic field vertical ring or flat ring high gradient magnetic separator with a separation magnetic field of 1000mT to 1500mT.

6. The comprehensive utilization method according to claim 1, characterized in that: In step S4, a hydrocyclone or a spiral classifier is used to separate and classify the selected fine sand to obtain primary kaolin with a mesh size of -325 to 0 and feldspar products with a mesh size of -40 to +325.

7. The comprehensive utilization method according to claim 1, characterized in that: In step S5, a high gradient strong magnetic separator is used and two stages of magnetic separation are continuously performed under the condition of separation magnetic field of 1450mT to 2000mT, thereby obtaining kaolin products and cement raw materials.

8. The comprehensive utilization method according to claim 7, characterized in that: The magnetic medium of the high gradient strong magnetic separator is made of 430# magnetic conductive stainless steel and the mesh size of the drawn steel mesh is set to 4×8 mm and 2×4 mm.

9. The comprehensive utilization method according to claim 1, characterized in that: The SiO2 grade of the sand and gravel aggregate waste powder is 70%-80%, the Al2O3 grade is 10%-15%, and the Fe2O3 grade is 1%-1.5%.

10. The comprehensive utilization method according to claim 1, characterized in that: The yield of the cement raw material obtained in step S2 is 5%-6%, wherein the SiO2 grade is 55%-60% and the SiO2 distribution rate is 3%-4%, the Fe2O3 grade is 5%-6% and the Fe2O3 distribution rate is 20%-25%, the yield of the feldspar product obtained in step S4 is 25%-35%, wherein the SiO2 grade is 75%-80% and the SiO2 distribution rate is 0.01%-0.1%, the Fe2O3 grade is 15%-20% and the Fe2O3 distribution rate is 1%-1.5%, and the step S4 is The yield of the kaolin product obtained in step S5 is 10%-20%, and the Al2O3 grade is 25%-30%, and the Al2O3 distribution rate is 20%-25%, the Fe2O3 grade is 2%-3%, and the Fe2O3 distribution rate is 15%-20%. The yield of the cement raw material obtained in step S5 is 0.05%-0.2%, and the SiO2 grade is 40%-45%, and the SiO2 distribution rate is 0.01%-0.1%, the Fe2O3 grade is 15%-20%, and the Fe2O3 distribution rate is 1%-1.5%.

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