A stone powder-based mineral admixture, a preparation method and application thereof

Abstract

The application belongs to the technical field of building material preparation, and particularly relates to a stone powder-based mineral admixture and a preparation method and application thereof. The method comprises the following steps: sequentially performing water washing, soil removal, crushing and pressure filtration on tailings stone slag to obtain stone slag particles; mixing the stone slag particles with a dissolving acid solution to perform first ball milling to obtain first activated stone powder; mixing the first activated stone powder with an aluminum-containing active mineral to perform second ball milling to obtain second activated stone powder; mixing the second activated stone powder with a hydrophilic material to perform third ball milling to obtain hydrophilic stone powder; and drying, sorting and proportionally mixing the hydrophilic stone powder to obtain the stone powder-based mineral admixture. The stone powder-based mineral admixture has an average particle size of 300-400 mesh, a hydrophilic coefficient of >1.0, a 28-day activity index of >70%, and a water content of <1%. The stone powder-based mineral admixture is used for preparing concrete, and can significantly improve the mechanical properties of the concrete.

Description

Technical Field

[0001] This invention belongs to the field of building material preparation technology, and specifically relates to a stone powder-based mineral admixture, its preparation method, and its application. Background Technology

[0002] The production of manufactured sand and crushed stone typically generates a large amount of stone slag tailings. Stone slag is a mixture of stone chips, stone powder, soil, and water, which is difficult to process and exists in massive quantities. Currently, it can only be centrally recycled and transported to landfills for disposal, negatively impacting the ecological environment and wasting land and mineral resources. If processed stone slag were used as a mineral admixture in concrete, it would not only provide the concrete industry with a wide range of mineral admixtures but also solve the environmental problems caused by stone slag accumulation.

[0003] However, the activity of stone powder, formed from simple grinding of stone slag, is far lower than that of active admixtures such as fly ash and mineral powder. The main reason for the low chemical activity of stone powder is that most of it is crystalline, with only a very small portion being glassy, ​​but the glassy portion is the primary source of chemical activity. Therefore, stone powder mainly functions as a physical filler in concrete, with low chemical activity. Furthermore, the poor hydrophilicity of stone powder surfaces leads to easy segregation and bleeding in the prepared concrete, resulting in poor homogeneity and affecting construction quality.

[0004] Therefore, it is necessary to propose a method for preparing stone powder-based mineral admixtures to improve the chemical activity and water retention of the prepared stone powder-based mineral admixtures, so that they can effectively ensure the mechanical properties and low bleeding rate of concrete when used in concrete preparation. Summary of the Invention

[0005] To address the above problems, the present invention adopts the following technical solution: a method for preparing a stone powder-based mineral admixture, the method comprising the following steps:

[0006] The tailing stone slag is sequentially washed with water to remove soil, crushed and filtered to obtain stone slag particles.

[0007] The stone slag particles were mixed with the dissolved acid solution and subjected to a first ball milling process to obtain the first activated stone powder;

[0008] The first activated stone powder is mixed with aluminum-containing active minerals and then ball-milled to obtain the second activated stone powder.

[0009] The second activated stone powder is mixed with a hydrophilic material and then ball-milled in a third process to obtain hydrophilic stone powder.

[0010] Hydrophilic stone powder is dried, sorted, and mixed in proportion to obtain stone powder-based mineral admixture.

[0011] Furthermore, the water washing and soil removal process involves screening the tailings stone slag to remove mud and organic matter; the crushing speed is 1000-1500 r / min, and the average particle size of the crushed stone slag is 0.3-0.6 mm.

[0012] The moisture content of the stone slag particles after pressure filtration is <5%.

[0013] Furthermore, the mass ratio of stone slag particles to dissolved acid is 100:5-100:2; the acid in the dissolved acid includes waste acid from etching silicon wafers and waste acid from producing titanium dioxide, which are mixed in a volume ratio of 9:1-1:9.

[0014] Furthermore, the rotation speed of the first ball mill is 22-25 r / min, and the milling time is 40-50 min.

[0015] Furthermore, aluminum-containing active minerals include clay brick powder, aluminum ash, or metakaolin powder.

[0016] Furthermore, the rotation speed of the second ball mill is 18-22 r / min, and the milling time is 10-20 min.

[0017] Furthermore, the hydrophilic material is a mixed solution of a hydrophilic coupling agent and polyethylene glycol; the hydrophilic coupling agent includes one or more of hydrophilic silane coupling agents, hydroxypropyl methylcellulose, methylcellulose, and starch ether.

[0018] Furthermore, the rotation speed of the third ball mill is 15-18 r / min, and the milling time is 5-10 min.

[0019] Furthermore, after drying and sorting, the hydrophilic stone powder is divided into two types: stone powder with a particle size greater than 300 mesh and stone powder with a particle size less than 300 mesh. The two types of stone powder with a particle size greater than 300 mesh and stone powder with a particle size less than 300 mesh are mixed in a mass ratio of 7:3 to 5:5 to obtain stone powder-based mineral admixture.

[0020] In addition, the present invention also proposes a stone powder-based mineral admixture, which is prepared by the above-described preparation method; the average particle size of the stone powder-based mineral admixture is 300-400 mesh; the hydrophilicity coefficient of the stone powder-based mineral admixture is >1.0; the 28-day activity index of the stone powder-based mineral admixture is >70%; and the moisture content of the stone powder-based mineral admixture is <1%.

[0021] In addition, the present invention also proposes an application of the stone powder-based mineral admixture as described above, which is used to prepare concrete.

[0022] In this invention, stone slag, after being washed, crushed, and filtered, undergoes a chemical reaction with a dissolving acid solution. The stone slag is then ball-milled to form small-particle-size stone powder. The specific surface area of ​​the stone powder is much larger than that of the stone slag, increasing the number of reaction sites and improving its chemical activity. The chemical reaction with the dissolving acid solution roughens the surface of the stone powder particles, increasing the contact area between water molecules and the stone slag particle surface, reducing the contact angle of the stone slag particles, and improving their hydrophilicity. This surface roughening also results in a tighter and more reliable bond between the stone powder and cement hydration products, indirectly improving the 28-day activity index of the stone powder. Simultaneously, the activated stone powder generated by the reaction also acts as a concrete early-strength agent, promoting the early formation of cement hydration products and further improving the water retention of stone powder concrete.

[0023] This preparation method utilizes the synergistic effect of three steps: activation with dissolved mixed acid, synergistic activation with aluminum-containing active minerals, and addition of hydrophilic materials. This results in a stone powder-based mineral admixture with low moisture content, small particle size, high activity, and good water retention. Furthermore, it fully leverages the physical filling effect of stone powder. When the highly active stone powder-based mineral admixture is used in concrete, its mechanical properties can be significantly improved.

[0024] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention will be realized and obtained through the description. Detailed Implementation

[0025] To make the objectives, 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. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Common rocks used in the production of sand and gravel include limestone, dolomite, granite, sandstone, tuff, basalt, quartz, and diorite, with main components such as SiO2, NaAlSi3O8, KAlSi3O8, CaCO3, and MgCO3. The waste acid from etching silicon wafers mainly consists of hydrofluoric acid, with small amounts of nitric acid and fluorosilicic acid. The waste acid from titanium dioxide production mainly consists of dilute sulfuric acid, with sulfates such as FeSO4, Al2(SO4)3, and MgSO4. The chemical reaction mechanism is as follows:

[0027] SiO2 + HF → SiF4↑ + H2O;

[0028] KAlSi3O8+HF+H2SO4→K2SO4+Al2(SO4)3+SiF4↑+H2O;

[0029] NaAlSi3O8+HF+H2SO4→Na2SO4+Al2(SO4)3+SiF4↑+H2O;

[0030] CaCO3+H2SO4→CaSO4+H2O+CO2↑;

[0031] MgCO3+H2SO4→MgSO4+H2O+CO2↑;

[0032] When sulfuric acid and hydrofluoric acid coexist, the rate of the above chemical reaction is not high at room temperature. However, during ball milling, the internal temperature of the ball mill gradually increases, thus accelerating the chemical reaction. The K₂SO₄, Na₂SO₄, Al₂(SO₄)₃, CaSO₄, and MgSO₄ obtained from the dissolution of stone slag particles, as well as sulfates, nitric acid, and fluorosilicic acid mixed in with the waste acid, can all participate in or promote the hydration reaction of cement, generating more cement hydration products. This increases the strength and durability of concrete and also solves the problem of wastewater treatment during the production of monocrystalline silicon and titanium dioxide.

[0033] Aluminum was introduced into the stone powder by mixing it with aluminum-containing active minerals after the first activation. These active minerals react chemically with the sulfates in the first-activated stone powder during concrete mixing, forming hydration products such as calcium vanadate (AFt) and monoclinic hydrated calcium sulfoaluminate (AFm). This synergistic activation effect was demonstrated during the activation process of the stone powder-based mineral admixture in concrete, promoting the formation of hydration products and increasing the 28-day activity index of the admixture. A hydrophilic film was then attached to the stone powder surface using a hydrophilic material, reducing the interfacial tension at the stone powder-water interface and further decreasing the contact angle. Finally, the stone powder after three ball milling processes was sorted and remixed in proportion to reduce the porosity of the stone powder particles, resulting in a stone powder-based mineral admixture with a more optimized particle size.

[0034] Example 1

[0035] Example 1 of this invention proposes a method for preparing a stone powder-based mineral admixture, which includes the following steps:

[0036] (1) Quartz tailings stone slag is screened in a water-washed drum sand screen with a screen size of 0.15mm to obtain stone slag with soil and organic matter removed; the stone slag after water washing and soil removal is crushed in a double roller stone powder crusher to obtain fine stone slag particles with an average particle size of 0.5mm and a rotation speed of 1200r / min; the fine stone slag particles are filtered in a tailings sludge filter press, and the moisture content of the stone slag particles after the filter press is 4.8%.

[0037] (2) The stone slag particles obtained in step (1) are mixed with the dissolving acid solution and ball-milled at a speed of 25 r / min to obtain the first activated stone powder. The first ball milling time is 50 min. The mass ratio of stone slag particles to dissolving acid solution is 100:5. The mixed acid in the dissolving acid solution is waste acid from etching silicon wafers and waste acid from producing titanium dioxide. The mixed volume ratio of waste acid from etching silicon wafers and waste acid from producing titanium dioxide is 9:1.

[0038] (3) The first activated stone powder obtained in step (2) is mixed with metakaolin powder and ball milled at a speed of 22 r / min to obtain the second activated stone powder supplemented with aluminum. The second ball milling time is 20 min.

[0039] (4) The second activated stone powder obtained in step (3) is mixed with a mixed solution of hydrophilic silane coupling agent and polyethylene glycol. The volume ratio of hydrophilic silane coupling agent to polyethylene glycol in the mixed solution is 2:8, the concentration of the mixed solution is 10%, and the mass ratio of the mixed solution to the second activated stone powder is 5:1000. The third ball milling is carried out at a speed of 18 r / min to obtain stone powder with a hydrophilic surface. The third ball milling time is 10 min.

[0040] (5) The hydrophilic stone powder obtained in step (4) is dried by a rapid flash dryer and then sorted by a cyclone classifier. The two types of stone powder with a particle size greater than 300 mesh and less than 300 mesh are mixed in a mass ratio of 7:3 to obtain a quartz stone powder-based mineral admixture with an average particle size of 300 mesh, a moisture content of 0.8%, a hydrophilicity coefficient of 1.5 (tested according to the standard JTG F40 "Technical Specification for Construction of Highway Asphalt Pavement"), and a 28-day activity index of 73% (tested according to the standard GB / T 35164 "Limestone Powder for Cement Mortar and Concrete").

[0041] Example 2

[0042] Example 2 of this invention proposes a method for preparing a stone powder-based mineral admixture, which includes the following steps:

[0043] (1) The limestone tailings stone slag is screened by a water washing drum sand screen with a screen size of 0.15mm to obtain stone slag after removing mud and organic matter; the stone slag after water washing and soil removal is crushed in a double roller stone powder crusher to obtain fine stone slag particles with an average particle size of 0.3mm and a rotation speed of 1000r / min; the fine stone slag particles are filtered in a tailings sludge filter press, and the moisture content of the stone slag particles after the filter press is 2.8%.

[0044] (2) The stone slag particles obtained in step (1) are mixed with the dissolving acid solution and ball-milled at a speed of 22 r / min to obtain the first activated stone powder. The first ball milling time is 40 min. The mass ratio of stone slag particles to dissolving acid solution is 100:2. The mixed acid in the dissolving acid solution is waste acid from etching silicon wafers and waste acid from producing titanium dioxide. The mixed volume ratio of waste acid from etching silicon wafers and waste acid from producing titanium dioxide is 1:9.

[0045] (3) The first activated stone powder obtained in step (2) is mixed with clay brick powder and ball milled at a speed of 18 r / min to obtain the second activated stone powder supplemented with aluminum. The second ball milling time is 10 min.

[0046] (4) The second activated stone powder obtained in step (3) is mixed with a mixed solution of hydroxypropyl methylcellulose and polyethylene glycol. The volume ratio of hydroxypropyl methylcellulose to polyethylene glycol in the mixed solution is 2:8, the concentration of the mixed solution is 10%, and the mass ratio of the mixed solution to the second activated stone powder is 5:1000. A third ball milling is performed at a speed of 15 r / min to obtain a hydrophilic stone powder. The third ball milling time is 5 min. The hydrophilic coupling agent is:

[0047] (5) The hydrophilic stone powder obtained in step (4) is dried by a rapid flash dryer and then sorted by a cyclone classifier. The two types of stone powder with a particle size greater than 300 mesh and less than 300 mesh are mixed in a mass ratio of 7:3 to obtain a limestone powder-based mineral admixture with an average particle size of 400 mesh, a moisture content of 0.4%, a hydrophilicity coefficient of 1.2 (tested according to the standard JTG F40 "Technical Specification for Construction of Asphalt Pavement of Highway"), and a 28-day activity index of 83% (tested according to the standard GB / T 35164 "Limestone Powder for Cement Mortar and Concrete").

[0048] Example 3

[0049] Example 3 of this invention proposes a method for preparing a stone powder-based mineral admixture, which includes the following steps:

[0050] (1) Basalt tailings stone slag is screened by a water washing drum sand screen with a screen size of 1.5mm to obtain stone slag after removing mud and organic matter; the stone slag after water washing and soil removal is crushed in a double roller stone powder crusher to obtain fine stone slag particles with an average particle size of 0.6mm and a rotation speed of 1500r / min; the fine stone slag particles are then filtered in a tailings sludge filter press, and the moisture content of the stone slag particles after filtration is 3.3%.

[0051] (2) The stone slag particles obtained in step (1) are mixed with the dissolving acid solution and ball-milled at a speed of 24 r / min to obtain the first activated stone powder. The first ball milling time is 45 min. The mass ratio of stone slag particles to dissolving acid solution is 100:4. The mixed acid in the dissolving acid solution is waste acid from etching silicon wafers and waste acid from producing titanium dioxide. The mixed volume ratio of waste acid from etching silicon wafers and waste acid from producing titanium dioxide is 6:4.

[0052] (3) The first activated stone powder obtained in step (2) is mixed with aluminum ash and ball-milled at a speed of 20 r / min to obtain the second activated stone powder supplemented with aluminum element. The second ball-milling time is 15 min.

[0053] (4) The second activated stone powder obtained in step (3) is mixed with a mixed solution of starch ether and polyethylene glycol. The volume ratio of starch ether to polyethylene glycol in the mixed solution is 2:8, the concentration of the mixed solution is 10%, and the mass ratio of the mixed solution to the second activated stone powder is 5:1000. The third ball milling is carried out at a speed of 16 r / min to obtain stone powder with a hydrophilic surface. The third ball milling time is 8 min.

[0054] (5) The surface hydrophilic stone powder obtained in step (4) is dried by a rapid flash dryer and then sorted by a cyclone classifier. The two types of stone powder with a particle size greater than 300 mesh and less than 300 mesh are mixed in a mass ratio of 7:3 to obtain a basalt powder-based mineral admixture with an average particle size of 325 mesh, a moisture content of 0.4%, a hydrophilicity coefficient of 1.3 (tested according to the standard JTG F40 "Technical Specification for Construction of Asphalt Pavement of Highway"), and a 28-day activity index of 78% (tested according to the standard GB / T 35164 "Limestone Powder for Cement Mortar and Concrete").

[0055] Comparative Example 1

[0056] Comparative Example 1 of the present invention provides a method for preparing a stone powder-based mineral admixture. The difference between the method for preparing the stone powder-based mineral admixture and Example 1 is that the mixed acid in the dissolved acid solution in step (2) is replaced with a single hydrofluoric acid in equal volume. All other aspects are the same as in Example 1.

[0057] Comparative Example 2

[0058] Comparative Example 2 of the present invention provides a method for preparing a stone powder-based mineral admixture. The difference between the method for preparing the stone powder-based mineral admixture and Example 1 is that in step (2), no dissolving acid is added during the first ball milling, while the rest are the same as in Example 1.

[0059] Comparative Example 3

[0060] Comparative Example 3 of the present invention provides a method for preparing a stone powder-based mineral admixture. The difference between the method for preparing the stone powder-based mineral admixture and Example 1 is that aluminum-containing active minerals are not added in the second ball milling process in step (3), while the rest are the same as in Example 1.

[0061] Comparative Example 4

[0062] Comparative Example 4 of the present invention provides a method for preparing a stone powder-based mineral admixture. The difference between the method for preparing the stone powder-based mineral admixture and Example 1 is that no hydrophilic material is added in the third ball milling process in step (4), and the rest is the same as in Example 1.

[0063] The stone powder-based mineral admixtures provided in Examples 1-3 and Comparative Examples 1-4 were used to prepare concrete according to the components and weight proportions of C30 concrete in Table 1. The resulting concrete was subjected to 28-day compressive strength tests in accordance with GB / T 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete". The results are shown in Table 2.

[0064] Table 1. Components and weight proportions of C30 concrete

[0065]

[0066] Table 2. Test results of bleeding rate and 28-day compressive strength of concrete.

[0067]

[0068] In summary, by washing, crushing, filtration, and ball milling the stone slag tailings, some of the effective chemical components in the stone slag are dissolved, forming chemical additives that promote cement hydration. Furthermore, by adding dissolving and mixing acid, activating the stone powder with aluminum-containing active minerals, and adding hydrophilic materials for hydrophilic treatment, the surface roughness of the stone powder is improved, resulting in a stronger bond with cement hydration products. The resulting stone powder-based mineral admixture has low moisture content, small particle size, and high activity. Combined with the physical filling effect of the stone powder-based mineral admixture, the prepared concrete can achieve a maximum 28-day compressive strength of 41.7 MPa, meeting the strength requirements of C30 concrete, thus realizing the resource utilization of stone slag tailings.

[0069] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a stone powder-based mineral admixture, characterized in that, The method includes the following steps: The tailing stone slag is sequentially washed with water to remove soil, crushed and filtered to obtain stone slag particles. Stone slag particles are mixed with dissolving acid solution and subjected to a first ball milling to obtain first activated stone powder; the acid in the dissolving acid solution includes waste acid from etching silicon wafers and waste acid from producing titanium dioxide, which are mixed in a volume ratio of 9:1 to 1:

9. The first activated stone powder is mixed with aluminum-containing active minerals and then ball-milled to obtain the second activated stone powder; the aluminum-containing active minerals include clay brick powder, aluminum ash or metakaolin powder. The second activated stone powder is mixed with a hydrophilic material and then ball-milled to obtain hydrophilic stone powder; the hydrophilic material is a mixed solution formed by mixing one of hydrophilic silane coupling agent, hydroxypropyl methylcellulose and starch ether with polyethylene glycol. Hydrophilic stone powder is dried, sorted, and mixed in proportion to obtain stone powder-based mineral admixture.

2. The method for preparing a stone powder-based mineral admixture according to claim 1, characterized in that, The wastewater is washed and screened to remove mud and organic matter from the tailings stone slag; the crushing speed is 1000-1500 r / min, and the average particle size of the crushed stone slag is 0.3-0.6 mm. The moisture content of the stone slag particles after pressure filtration is <5%.

3. The method for preparing a stone powder-based mineral admixture according to claim 1, characterized in that, The mass ratio of stone slag particles to dissolved acid is 100:5-100:

2.

4. The method for preparing a stone powder-based mineral admixture according to claim 3, characterized in that, The first ball milling speed is 22-25 r / min, and the first ball milling time is 40-50 min.

5. The method for preparing a stone powder-based mineral admixture according to claim 1, characterized in that, The second ball milling speed is 18-22 r / min, and the second ball milling time is 10-20 min.

6. The method for preparing a stone powder-based mineral admixture according to claim 1, characterized in that, The third ball milling speed is 15-18 r / min, and the third ball milling time is 5-10 min.

7. The method for preparing a stone powder-based mineral admixture according to claim 1, characterized in that, After drying and sorting, hydrophilic stone powder is divided into two types: stone powder with a particle size greater than 300 mesh and stone powder with a particle size less than 300 mesh. The two types of stone powder with a particle size greater than 300 mesh and stone powder with a particle size less than 300 mesh are mixed in a mass ratio of 7:3-5:5 to obtain stone powder-based mineral admixture.

8. A stone powder-based mineral admixture, characterized in that, The stone powder-based mineral admixture is prepared by the preparation method according to any one of claims 1-7; The average particle size of the stone powder-based mineral admixture is 300-400 mesh; The hydrophilicity coefficient of stone powder-based mineral admixtures is >1.0; The 28-day activity index of stone powder-based mineral admixtures is >70%; The moisture content of the stone powder-based mineral admixture is <1%.

9. An application of the stone powder-based mineral admixture as described in claim 8, characterized in that, The stone powder-based mineral admixture is used to prepare concrete.

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