Modified phosphogypsum material for highway under new excitation system and preparation method and device thereof

Abstract

The present invention relates to a phosphogypsum modified material for highways under a new excitation system, and a preparation method and device thereof, belonging to the technical field of highway engineering in transportation engineering. The modified material comprises the following raw materials in weight percentage: 80% to 90% phosphogypsum, 10% to 20% modifier, totaling 100%; it also comprises water, the mass of which is 15% to 18% of the total mass of the phosphogypsum and the activator; the modifier comprises the following raw materials: calcium oxide, silicon dioxide, ferric oxide, aluminum oxide, mineral powder, tricalcium silicate, calcium carbonate, sodium silicate, coupling agent, iron powder, and rubber powder. The phosphogypsum modified material of the present invention also exhibits the advantages of excellent strength growth and improved stability in terms of long-term performance development, is highly environmentally friendly, does not pollute the environment, soil, and water bodies, and is economical, does not increase the overall cost of the project, and is easy to promote and apply.

Description

Technical Field

[0001] The present invention belongs to the technical field of highway engineering in transportation engineering, and particularly relates to a phosphogypsum modified material for highways under a new excitation system and a preparation method and device thereof. Background Art

[0002] Currently, we must effectively promote the efficient and high-quality utilization of phosphorus resources and the reduction, resource utilization, harmless treatment, and comprehensive utilization of phosphogypsum. my country is one of the countries with the largest production and storage of phosphogypsum materials. According to statistics from the China Phosphate and Compound Fertilizer Industry Association, by 2023, my country's annual production of phosphogypsum materials will be approximately 81 million tons, with cumulative storage exceeding 800 million tons, primarily concentrated in Yunnan, Guizhou, Hubei, Sichuan, and Anhui provinces. A document proposes that by 2026, the comprehensive utilization rate of phosphogypsum will reach 65%, and that the comprehensive consumption volume (including comprehensive utilization and harmless treatment) will be in dynamic balance with the production volume. Improving the comprehensive utilization volume and quality of phosphogypsum through multiple channels and scenarios has become a major task and a challenge to overcome at this stage.

[0003] The main component of phosphogypsum is CaSO4·2H2O, and its main chemical components include SO3, CaO, SiO2, P2O5, Al2O3, Fe2O3, MgO, Na2O, K2O, F and crystal water. Impurities such as fluoride, free phosphoric acid, P2O5 and phosphates are prone to cause environmental pollution. Long-term exposure to phosphogypsum may have adverse effects on the human body, the environment, groundwater and soil.

[0004] In highway construction, phosphogypsum solid waste is often used in the road pavement base layer. Its widespread use can reduce environmental pollution and impact. However, currently, there is no effective treatment method for phosphogypsum. Cement-based materials are the primary method used to solidify phosphogypsum, a method that exhibits significant drawbacks, including low early strength, poor water and volume stability, and expansion cracking. Therefore, there is an urgent need to develop targeted, high-quality, comprehensive technologies for the high-dosage, high-quality application of phosphogypsum solid waste.

[0005] Currently, in highway projects, phosphogypsum solid waste is primarily used as a road base to replace cement-stabilized gravel base. This refers to the utilization of phosphogypsum solid waste, primarily through cement-based material solidification. This solidification is performed using existing cement-stabilized gravel base mixing plants, and is rolled and formed using heavy-duty rollers to a designed compaction degree. Through maintenance under specified conditions, the phosphogypsum reaches a certain strength and stability, allowing it to be used as a highway base material, replacing the cement-stabilized gravel base. This method exhibits significant drawbacks. First, the use of cement to solidify phosphogypsum materials results in low early strength, poor water stability, and poor volume stability, making it susceptible to expansion and cracking. Second, the conventional factory mixing method employed suffers from low mixing speeds, poor mixing blade crushing, and poor uniformity in mixing the phosphogypsum and added materials. Third, the compaction control method employed for rolling and forming the phosphogypsum material fails to achieve the optimal compaction and forming effect for the phosphogypsum material, resulting in low strength and poor stability in the solidified phosphogypsum material, which fails to meet the design standards and objectives of the engineering application.

[0006] Therefore, there is an urgent need to develop targeted high-dosage, high-quality comprehensive application technology for phosphogypsum solid waste. How to overcome the shortcomings of existing technologies is an urgent problem that needs to be solved in this technical field. Summary of the Invention

[0007] The purpose of the present invention is to address the deficiencies of the prior art and to provide a phosphogypsum modified material for highway use under a new excitation system and a preparation method and device thereof.

[0008] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] A phosphogypsum modified material for highways under a new excitation system, comprising the following raw materials calculated by weight: 80% to 90% of phosphogypsum, 10% to 20% of a modifier, a total of 100%;

[0010] It also includes water, the mass of which is 15% to 18% of the total mass of phosphogypsum and modifier;

[0011] The modifier includes the following raw materials in parts by weight:

[0012] 4.8-5.2 parts of calcium oxide, 5.8-6.2 parts of silicon dioxide, 3.9-4.1 parts of aluminum oxide, 9.9-10.1 parts of ferric oxide, 39-41 parts of mineral powder, 29-31 parts of tricalcium silicate, 1.9-2.1 parts of calcium carbonate, 0.9-1.1 parts of sodium silicate, 0.9-1.1 parts of coupling agent, 0.48-0.52 parts of iron powder, and 0.48-0.52 parts of rubber powder.

[0013] Furthermore, it is preferred that the coupling agent is an aluminate coupling agent; the activity index of the mineral powder is required to be no less than 75%; the iron powder is required to be no less than 500 mesh; the purity of the rubber powder is required to be no less than 99% and no less than 500 mesh.

[0014] The method for preparing the modified phosphogypsum material for highways under the above-mentioned new excitation system comprises the following steps:

[0015] Step 1, ingredients: weigh phosphogypsum, modifier and water;

[0016] Step 2, mixing: stirring the phosphogypsum, modifier and water weighed in step 1 until they are uniformly mixed to obtain a phosphogypsum modified material; wherein the stirring speed is not less than 500 r / min;

[0017] Step 3, compaction test: The compaction density control index and the moisture content control index of the phosphogypsum modified material are tested. If the compaction control index is not less than 98% of the maximum dry density and the moisture content control index is within the range of 5mm-10mm, the test is passed and the material is used in the design of the highway pavement base structure.

[0018] If the test fails, the batch of materials cannot be used in the design of highway pavement base structure and should be discarded.

[0019] Furthermore, preferably, in step 2, the stirring adopts a double S composite full-shaft densely distributed crushing rod type stirring device, and the double S composite full-shaft densely distributed crushing rod type stirring device includes a support base;

[0020] A stirring chamber is mounted on the support base; the stirring chamber can rotate relative to the support base;

[0021] The top of the stirring chamber is provided with a feed and a discharge port;

[0022] There should be fixed covers on the feed and discharge ports;

[0023] Also includes electric motors and high-speed rotating machines;

[0024] The power output end of the electric motor is connected to the power output end of the high-speed rotating machine to provide a power source for the high-speed rotating machine;

[0025] The stirring chamber is equipped with a high-speed rotating shaft, the other end of which extends out of the stirring chamber and is connected to the power output end of the high-speed rotating machine; the high-speed rotating machine is used to drive the high-speed rotating shaft to rotate;

[0026] The high-speed rotating shaft inside the mixing chamber is equipped with double S-type mixing blades and crushing rod-type mixing blades densely distributed throughout the shaft;

[0027] Furthermore, preferably, a stirring chamber is mounted on the support base via a fixture;

[0028] The double S-type stirring blades are symmetrically welded on the high-speed rotating shaft in the stirring chamber, and the full-axis dense crushing rod stirring blades are welded around the high-speed rotating shaft.

[0029] Furthermore, preferably, it further comprises a stirring time controller, a stirring speed controller, a start-stop controller and an emergency stop button;

[0030] The stirring time controller is used to control the stirring time;

[0031] The stirring speed controller is used to control the stirring speed;

[0032] The start-stop controller is used to control the start and stop of the motor when the motor is powered on;

[0033] The emergency stop button is used to control the power supply to the motor.

[0034] Furthermore, preferably, in step 3, the wetness control index is detected by using a phosphogypsum modified material density compaction wetness measuring device;

[0035] The device for measuring density, compaction and moisture content of phosphogypsum modified materials comprises a pressure-bearing structure 2-1, a contact pressure block and a cylindrical forming die;

[0036] The top and bottom of the cylindrical forming mold are both equipped with contact pressure blocks, and a pressure-bearing structure is installed on the side of the contact pressure blocks away from the cylindrical forming mold;

[0037] There are scale lines on the contact pressure block;

[0038] There is also a scale alarm on the contact block; when the edge of the cylindrical forming mold is flush with the scale line of 0cm, the scale alarm will sound an alarm;

[0039] Four immersion humidity test tubes are symmetrically arranged around the contact pressing block. The immersion humidity test tubes pass through the contact pressing block, with one side extending out of the contact pressing block and the other side directly contacting the phosphogypsum modified material in the cylindrical forming mold;

[0040] A filter is provided at the bottom of the immersion humidity test tube, and a water-absorbing and color-changing desiccant is provided inside;

[0041] A humidity observation line is provided on the humidity test tube.

[0042] Furthermore, preferably, the scale line on one side of the contact pressure block close to the pressure-bearing structure is 0 cm, and the scale line on the other side is 5 cm;

[0043] The 0 cm scale of the wetness observation line is flush with the side of the contact block close to the pressure-bearing structure, and a 1 cm scale range is set upward.

[0044] The present invention also provides the above-mentioned double S composite full-shaft densely distributed crushing rod type stirring device.

[0045] The present invention also provides the device for measuring the density, compaction and wettability of the phosphogypsum modified material.

[0046] Preferably, the modifier comprises the following raw materials in parts by weight:

[0047] 5 parts of calcium oxide, 6 parts of silicon dioxide, 4 parts of aluminum oxide, 10 parts of ferric oxide, 40 parts of mineral powder, 30 parts of tricalcium silicate, 2 parts of calcium carbonate, 1 part of sodium silicate, 1 part of coupling agent, 0.5 parts of iron powder, and 0.5 parts of rubber powder.

[0048] Preferably, aluminate coupling agent powder is used as the coupling agent. The activity index of the mineral powder must be no less than 75%. The activity index of the mineral powder refers to the ratio of the compressive strength of the mortar specimen after the mineral powder is mixed with cement to the compressive strength of the pure cement mortar specimen within a specified age (7 days). The iron powder must be no less than 500 mesh (particle size less than 30μm). The purity of the rubber powder must be no less than 99% and no less than 500 mesh (particle size less than 30μm).

[0049] In the present invention, the motor provides power, and the high-speed rotary machine forms a higher rotation speed through a mechanical combination of large and small gears under the power of the motor, thereby achieving uniform mixing of the phosphogypsum mixture.

[0050] In the present invention, a stirring chamber is mounted on the support base via a fixture. During the stirring process, the stirring chamber and the fixture are fixed together, and the stirring chamber itself is fixed and cannot rotate. At this time, the high-speed rotating shaft in the stirring chamber can rotate. After the stirring process is completed, the stirring chamber and the fixture are released, and it can be manually rotated. This function can only be realized after the stirring process stops.

[0051] In this invention, the double S-shaped agitator blades are in an inverted "S" shape, with two double "S"s combined forming an inverted "8" shape. The fully distributed, breaker-bar-type agitator blades are cylindrical in shape. In addition to the double S-shaped agitator blades, the high-speed rotating shaft is also equipped with fully distributed, breaker-bar-type agitator blades at other locations.

[0052] In the present invention, the cylindrical forming mold preferably has two sizes of inner diameters of 100 mm and 150 mm, and two sizes of heights of 200 mm and 250 mm. The contact block preferably has two sizes of diameters of 100 mm and 150 mm, and two sizes of heights of 50 mm.

[0053] In response to the current status and defects of phosphogypsum materials in highway base layers, the present invention proposes a new curing system for phosphogypsum materials, conducts creative research and development from three aspects: modifier materials, mixing devices, and compaction control methods, and invents phosphogypsum modified materials for highways under the new excitation system, as well as a preparation method and device thereof, thus solving the difficult problem of applying phosphogypsum materials in highway pavement base layers.

[0054] Glossary:

[0055] (1) Cement-stabilized crushed stone base: This refers to a base that uses graded crushed stone as aggregate, a certain amount of cementitious material (mainly cement clinker) and sufficient mortar to fill the gaps between the aggregates, and is spread and compacted according to the interlocking principle. Its compaction is close to its density, and its strength mainly depends on the interlocking principle between the crushed stones. At the same time, there is sufficient mortar volume to fill the gaps between the aggregates. The cement content in the cement-stabilized crushed stone base is generally 3% to 6% of the mixture. It is not muddy in rain and has a solid surface. It is one of the pavement base paving types.

[0056] (2) Unconfined compressive strength: refers to the ultimate strength of a specimen against axial pressure in the absence of lateral pressure. During the test, axial pressure is gradually applied to the specimen without lateral restraint (i.e., the surrounding pressure is zero). When the specimen breaks, clear fracture surface marks are often visible on the side of the specimen. The ultimate pressure at the time of failure is the unconfined compressive strength.

[0057] (3) Wetness: This is a new concept proposed by the present invention. It refers to a measurement indicator that uses certain technical means to test the amount of water squeezed out of the phosphogypsum mixture during the compaction process. It is used to directly evaluate the rationality of the moisture content in the phosphogypsum asphalt mixture and indirectly evaluate the compaction degree and curing degree of the phosphogypsum mixture.

[0058] In the present invention, the modifier includes the following raw materials: calcium oxide (CaO), silicon dioxide (SiO2), aluminum oxide (Al2O3), ferric oxide (Fe2O3), mineral powder, tricalcium silicate (3CaO·SiO2), calcium carbonate (CaCO3), sodium silicate (Na2O·nSiO2), coupling agent, iron powder, and rubber powder.

[0059] In the present invention, the stirring chamber can rotate, and the axis of rotation is parallel to the horizontal plane; when feeding, the stirring chamber opening is preferably facing upward; when discharging, the stirring chamber is preferably rotated about 45 degrees and the material is discharged at an angle.

[0060] In the present invention, preferably, all scales involved have a dimensional accuracy of 1 mm. In the scale ranges between 0-5 cm and 0-1 cm, the dimensional accuracy is 1 mm.

[0061] Compared with the prior art, the present invention has the following beneficial effects:

[0062] The present invention creatively proposes a new modifier for modifying phosphogypsum solid waste materials and achieving the strength and stability required by the project, avoiding the shortcomings of insufficient strength and poor stability caused by cement-based materials solidifying phosphogypsum materials. The new modifier can not only meet the project requirements within the specified growth period (generally requiring a 7-day unconfined compressive strength of not less than 4 MPa), but also exhibits excellent strength growth and stability improvement advantages in long-term performance development. It is highly environmentally friendly, has no pollution to the environment, soil, and water bodies, and has good economic efficiency without increasing the overall cost of the project.

[0063] The present invention proposes a high-speed (generally requiring a rotation speed of not less than 500r / min), efficient, crushing and uniform mixing method and device, abandoning the disadvantages of the existing conventional low stirring speed (the existing stirring speed is generally about 60r / min), poor blade crushing ability, and uneven mixing, and innovatively proposes a double S composite full-axis dense crushing rod superimposed high-speed rotation function. The method greatly increases the stirring speed and adds full-axis dense crushing rods and blades, thereby increasing the degree of crushing of the phosphogypsum material during the mixing process, reducing the agglomeration phenomenon in the phosphogypsum material, and increasing the uniformity of mixing of the phosphogypsum material with the added modifier and water, which is more conducive to the solidification and stability of the phosphogypsum material.

[0064] The present invention proposes a new compaction control standard and device, resolving the current problem of poor curing quality of phosphogypsum materials, which primarily relies on compaction density. While meeting the existing compaction density control standard (i.e., not less than the original compaction), this method adds a moisture content control standard for the modified phosphogypsum material. Specifically, after adding a modifier and water to the modified phosphogypsum material, the moisture extrusion at the water outlet is observed during indoor compaction. When the extruded moisture reaches the specified level, the compaction meets the project requirements, and the phosphogypsum material achieves optimal curing and stability. Excessive, insufficient, or no moisture outflow indicates excessive or insufficient moisture content, preventing optimal strength and stability performance after curing. Using the inventive moisture content control method proposed by the present invention during on-site compaction of phosphogypsum materials can effectively improve various performance indicators of the cured phosphogypsum material, reduce the amount of modifier material used, and save overall construction costs.

[0065] Compared to existing data, this invention demonstrates significant advantages in strength development, water stability, and volume stability for phosphogypsum road bases. Specifically, the 7-day unconfined compressive strength is consistently increased by approximately 40% compared to conventional cement, with even greater long-term strength enhancement. Furthermore, compared to existing conventional technologies, the invention exhibits even greater advantages in water stability and volume stability, demonstrating no cracking, expansion, or dispersion in long-term water immersion tests. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 Schematic diagram of a double S composite full-shaft densely distributed crushing rod stirring device;

[0067] Figure 2 Schematic diagram of the full-axis densely distributed crushing rod stirring blades;

[0068] Figure 3 This is a schematic diagram of a device for measuring density, compaction and moisture content of phosphogypsum modified materials;

[0069] Figure 4 This is a schematic diagram of the humidity test tube;

[0070] Figure 5 Schematic diagram of the bottom filter structure. DETAILED DESCRIPTION

[0071] The present invention is described in further detail below with reference to the embodiments.

[0072] Those skilled in the art will understand that the following examples are intended to illustrate the present invention only and should not be construed as limiting the scope of the present invention. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in the art or in the product specifications were used. Materials or equipment used without manufacturer identification are commercially available conventional products.

[0073] It will be understood by those skilled in the art that, unless otherwise stated, the singular forms "a", "an", "said" and "the" used herein may also include the plural forms. It should be further understood that the term "comprising" used in the specification of the present invention refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. It should be understood that when we say that an element is "connected" to another element, it can be directly connected to the other element, or there may be intermediate elements. The term "and / or" used herein includes any unit and all combinations of one or more associated listed items.

[0074] In the description of the present invention, unless otherwise specified, "plurality" means two or more. Terms such as "inner," "upper," and "lower" indicating positions or states are based on those shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They do not indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and are therefore not to be construed as limiting the present invention.

[0075] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "provided with" should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; and direct or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0076] Those skilled in the art will understand that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art in the art to which this invention belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art and, unless defined as such, will not be interpreted in an idealized or overly formal sense. Example 1

[0077] A phosphogypsum modified material for highways under a new excitation system, characterized in that it comprises the following raw materials in percentage by weight: 85% phosphogypsum, 15% modifier, and a total of 100%;

[0078] It also includes water, the mass of which is 15% of the total mass of phosphogypsum and modifier;

[0079] The modifier includes the following raw materials in parts by weight:

[0080] 5 parts of calcium oxide, 5.9 parts of silicon dioxide, 4 parts of aluminum oxide, 10 parts of ferric oxide, 40 parts of mineral powder, 30 parts of tricalcium silicate, 2 parts of calcium carbonate, 1 part of sodium silicate, 1 part of coupling agent, 0.49 parts of iron powder, and 0.51 parts of rubber powder.

[0081] The method for preparing a modified phosphogypsum material for highways under the new excitation system of this embodiment comprises the following steps:

[0082] Step 1, ingredients: weigh phosphogypsum, modifier and water;

[0083] Step 2, mixing: stirring the phosphogypsum, modifier and water weighed in step 1 until they are uniformly mixed to obtain a phosphogypsum modified material; wherein the stirring speed is not less than 500 r / min;

[0084] Step 3, compaction test: The compaction density control index and the moisture content control index of the phosphogypsum modified material are tested. If the compaction control index is not less than 98% of the maximum dry density and the moisture content control index is within the range of 5mm-10mm, the test is passed and the material is used in the design of the highway pavement base structure.

[0085] If the test fails, the batch of materials cannot be used in the design of highway pavement base structure and should be discarded. Example 2

[0086] A phosphogypsum modified material for highways under a new excitation system, characterized in that it comprises the following raw materials in percentage by weight: 80% phosphogypsum, 20% modifier, and a total of 100%;

[0087] It also includes water, the mass of which is 15% of the total mass of phosphogypsum and modifier;

[0088] The modifier includes the following raw materials in parts by weight:

[0089] 4.8 parts of calcium oxide, 5.8 parts of silicon dioxide, 3.9 parts of aluminum oxide, 9.9 parts of iron oxide, 39 parts of mineral powder, 29 parts of tricalcium silicate, 1.9 parts of calcium carbonate, 0.9 parts of sodium silicate, 0.9 parts of coupling agent, 0.48 parts of iron powder, and 0.48 parts of rubber powder.

[0090] The coupling agent used is aluminate coupling agent; the activity index of the mineral powder is required to be no less than 75%; the iron powder is required to be no less than 500 mesh; the purity of the rubber powder is required to be no less than 99% and no less than 500 mesh.

[0091] The method for preparing a modified phosphogypsum material for highways under the new excitation system of this embodiment comprises the following steps:

[0092] Step 1, ingredients: weigh phosphogypsum, modifier and water;

[0093] Step 2, mixing: stirring the phosphogypsum, modifier and water weighed in step 1 until they are uniformly mixed to obtain a phosphogypsum modified material; wherein the stirring speed is not less than 500 r / min;

[0094] Step 3, compaction test: The compaction density control index and the moisture content control index of the phosphogypsum modified material are tested. If the compaction control index is not less than 98% of the maximum dry density and the moisture content control index is within the range of 5mm-10mm, the test is passed and the material is used in the design of the highway pavement base structure.

[0095] If the test fails, the batch of materials cannot be used in the design of highway pavement base structure and should be discarded.

[0096] like Figures 1 to 5 As shown, in step 2, the stirring adopts a double S composite full-shaft densely distributed crushing rod type stirring device, and the double S composite full-shaft densely distributed crushing rod type stirring device includes a support base 1-13;

[0097] A stirring chamber 1-8 is mounted on the support base 1-13; the stirring chamber 1-8 can rotate relative to the support base 1-13;

[0098] The top of the stirring chamber 1-8 is provided with a feed and discharge port 1-6;

[0099] The feed and discharge ports 1-6 should be provided with fixed covers 1-7;

[0100] Also includes a motor 1-1 and a high-speed rotating machine 1-2;

[0101] The power output end of the motor 1-1 is connected to the power output end of the high-speed rotating machine 1-2, providing a power source for the high-speed rotating machine 1-2;

[0102] The stirring chamber 1-8 is equipped with a high-speed rotating shaft 1-3. The other end of the high-speed rotating shaft 1-3 extends out of the stirring chamber 1-8 and is connected to the power output end of the high-speed rotating machine 1-2. The high-speed rotating machine 1-2 is used to drive the high-speed rotating shaft 1-3 to rotate.

[0103] The high-speed rotating shaft 1-3 inside the stirring cavity 1-8 is equipped with double S stirring blades 1-4 and full-shaft densely distributed crushing rod stirring blades 1-5.

[0104] In step 3, during the compaction test, the wetness control index is tested using a density compaction wetness measuring device for the phosphogypsum modified material;

[0105] The device for measuring density, compaction and moisture content of phosphogypsum modified materials comprises a pressure-bearing structure 2-1, a contact pressing block 2-2 and a cylindrical forming mold 2-9;

[0106] The top and bottom of the cylindrical forming mold 2-9 are both installed with contact pressure blocks 2-2, and the side of the contact pressure blocks 2-2 away from the cylindrical forming mold 2-9 is installed with a pressure-bearing structure 2-1;

[0107] A scale line 2-3 is provided on the contact pressure block 2-2;

[0108] There is also a scale alarm 2-4 on the contact pressure block 2-2; when the edge of the cylindrical forming mold 2-9 is flush with the scale line 2-3 at 0 cm, the scale alarm 2-4 sounds an alarm;

[0109] Four immersion humidity test tubes 2-5 are symmetrically arranged around the contact block 2-2. The immersion humidity test tubes 2-5 pass through the contact block 2-2, with one side extending out of the contact block 2-2 and the other side directly contacting the phosphogypsum modified material in the cylindrical forming mold 2-9.

[0110] A filter screen 2-6 is provided at the bottom of the humidity test tube 2-5, and a water-absorbing and color-changing desiccant 2-8 is provided inside;

[0111] A wetness observation line 2-7 is provided on the wetness test tube 2-5. Example 3

[0112] A phosphogypsum modified material for highways under a new excitation system, characterized in that it comprises the following raw materials in percentage by weight: 90% phosphogypsum, 10% modifier, and a total of 100%;

[0113] It also includes water, the mass of which is 18% of the total mass of phosphogypsum and modifier;

[0114] The modifier includes the following raw materials in parts by weight:

[0115] 5.2 parts of calcium oxide, 6.2 parts of silicon dioxide, 4.1 parts of aluminum oxide, 10.1 parts of ferric oxide, 41 parts of mineral powder, 31 parts of tricalcium silicate, 2.1 parts of calcium carbonate, 1.1 parts of sodium silicate, 1.1 parts of coupling agent, 0.52 parts of iron powder, and 0.52 parts of rubber powder.

[0116] The coupling agent used is aluminate coupling agent; the activity index of the mineral powder is required to be no less than 75%; the iron powder is required to be no less than 500 mesh; the purity of the rubber powder is required to be no less than 99% and no less than 500 mesh.

[0117] The method for preparing a modified phosphogypsum material for highways under the new excitation system of this embodiment comprises the following steps:

[0118] Step 1, ingredients: weigh phosphogypsum, modifier and water;

[0119] Step 2, mixing: stirring the phosphogypsum, modifier and water weighed in step 1 until they are uniformly mixed to obtain a phosphogypsum modified material; wherein the stirring speed is not less than 500 r / min;

[0120] Step 3, compaction test: The compaction density control index and the moisture content control index of the phosphogypsum modified material are tested. If the compaction control index is not less than 98% of the maximum dry density and the moisture content control index is within the range of 5mm-10mm, the test is passed and the material is used in the design of the highway pavement base structure.

[0121] If the test fails, the batch of materials cannot be used in the design of highway pavement base structure and should be discarded.

[0122] like Figures 1 to 5 As shown, in step 2, the stirring adopts a double S composite full-shaft densely distributed crushing rod type stirring device, and the double S composite full-shaft densely distributed crushing rod type stirring device includes a support base 1-13;

[0123] A stirring chamber 1-8 is mounted on the support base 1-13; the stirring chamber 1-8 can rotate relative to the support base 1-13;

[0124] The top of the stirring chamber 1-8 is provided with a feed and discharge port 1-6;

[0125] The feed and discharge ports 1-6 should be provided with fixed covers 1-7;

[0126] Also includes a motor 1-1 and a high-speed rotating machine 1-2;

[0127] The power output end of the motor 1-1 is connected to the power output end of the high-speed rotating machine 1-2, providing a power source for the high-speed rotating machine 1-2;

[0128] The stirring chamber 1-8 is equipped with a high-speed rotating shaft 1-3. The other end of the high-speed rotating shaft 1-3 extends out of the stirring chamber 1-8 and is connected to the power output end of the high-speed rotating machine 1-2. The high-speed rotating machine 1-2 is used to drive the high-speed rotating shaft 1-3 to rotate.

[0129] The high-speed rotating shaft 1-3 inside the stirring cavity 1-8 is equipped with double S stirring blades 1-4 and full-shaft densely distributed crushing rod stirring blades 1-5.

[0130] In step 3, during the compaction test, the wetness control index is tested using a density compaction wetness measuring device for the phosphogypsum modified material;

[0131] The device for measuring density, compaction and moisture content of phosphogypsum modified materials comprises a pressure-bearing structure 2-1, a contact pressing block 2-2 and a cylindrical forming mold 2-9;

[0132] The top and bottom of the cylindrical forming mold 2-9 are both installed with contact pressure blocks 2-2, and the side of the contact pressure blocks 2-2 away from the cylindrical forming mold 2-9 is installed with a pressure-bearing structure 2-1;

[0133] A scale line 2-3 is provided on the contact pressure block 2-2;

[0134] There is also a scale alarm 2-4 on the contact pressure block 2-2; when the edge of the cylindrical forming mold 2-9 is flush with the scale line 2-3 at 0 cm, the scale alarm 2-4 sounds an alarm;

[0135] Four immersion humidity test tubes 2-5 are symmetrically arranged around the contact block 2-2. The immersion humidity test tubes 2-5 pass through the contact block 2-2, with one side extending out of the contact block 2-2 and the other side directly contacting the phosphogypsum modified material in the cylindrical forming mold 2-9.

[0136] A filter screen 2-6 is provided at the bottom of the humidity test tube 2-5, and a water-absorbing and color-changing desiccant 2-8 is provided inside;

[0137] A wetness observation line 2-7 is provided on the wetness test tube 2-5.

[0138] A stirring chamber 1-8 is mounted on the support base 1-13 via a fixture 1-14;

[0139] The double S-shaped stirring blades are symmetrically welded on the high-speed rotating shaft 1-3 in the stirring chamber 1-8, and the full-axis densely distributed crushing rod stirring blades 1-5 are welded on the high-speed rotating shaft 1-3 around the high-speed rotating shaft 1-3;

[0140] The scale line 2-3 on one side of the contact pressure block 2-2 close to the pressure-bearing structure 2-1 is 0 cm, and the scale line 2-3 on the other side is 5 cm;

[0141] The 0 cm scale of the wetness observation line 2-7 is flush with the side of the contact pressure block 2-2 close to the pressure-bearing structure 2-1, and a 1 cm scale range is set upward. Example 4

[0142] A phosphogypsum modified material for highways under a new excitation system, characterized in that it comprises the following raw materials in percentage by weight: 83% phosphogypsum, 17% modifier, and a total of 100%;

[0143] It also includes water, the mass of which is 17% of the total mass of phosphogypsum and modifier;

[0144] The modifier includes the following raw materials in parts by weight:

[0145] 5 parts of calcium oxide, 6 parts of silicon dioxide, 4 parts of aluminum oxide, 10 parts of ferric oxide, 40 parts of mineral powder, 30 parts of tricalcium silicate, 2 parts of calcium carbonate, 1 part of sodium silicate, 1 part of coupling agent, 0.5 parts of iron powder, and 0.5 parts of rubber powder.

[0146] The coupling agent used is aluminate coupling agent; the activity index of the mineral powder is required to be no less than 75%; the iron powder is required to be no less than 500 mesh; the purity of the rubber powder is required to be no less than 99% and no less than 500 mesh.

[0147] The method for preparing a modified phosphogypsum material for highways under the new excitation system of this embodiment comprises the following steps:

[0148] Step 1, ingredients: weigh phosphogypsum, modifier and water;

[0149] Step 2, mixing: stirring the phosphogypsum, modifier and water weighed in step 1 until they are uniformly mixed to obtain a phosphogypsum modified material; wherein the stirring speed is not less than 500 r / min;

[0150] Step 3, compaction test: The compaction density control index and the moisture content control index of the phosphogypsum modified material are tested. If the compaction control index is not less than 98% of the maximum dry density and the moisture content control index is within the range of 5mm-10mm, the test is passed and the material is used in the design of the highway pavement base structure.

[0151] If the test fails, the batch of materials cannot be used in the design of highway pavement base structure and should be discarded.

[0152] like Figures 1 to 5 As shown, in step 2, the stirring adopts a double S composite full-shaft densely distributed crushing rod type stirring device, and the double S composite full-shaft densely distributed crushing rod type stirring device includes a support base 1-13;

[0153] A stirring chamber 1-8 is mounted on the support base 1-13; the stirring chamber 1-8 can rotate relative to the support base 1-13;

[0154] The top of the stirring chamber 1-8 is provided with a feed and discharge port 1-6;

[0155] The feed and discharge ports 1-6 should be provided with fixed covers 1-7;

[0156] Also includes a motor 1-1 and a high-speed rotating machine 1-2;

[0157] The power output end of the motor 1-1 is connected to the power output end of the high-speed rotating machine 1-2, providing a power source for the high-speed rotating machine 1-2;

[0158] The stirring chamber 1-8 is equipped with a high-speed rotating shaft 1-3. The other end of the high-speed rotating shaft 1-3 extends out of the stirring chamber 1-8 and is connected to the power output end of the high-speed rotating machine 1-2. The high-speed rotating machine 1-2 is used to drive the high-speed rotating shaft 1-3 to rotate.

[0159] The high-speed rotating shaft 1-3 inside the stirring cavity 1-8 is equipped with double S stirring blades 1-4 and full-shaft densely distributed crushing rod stirring blades 1-5.

[0160] In step 3, during the compaction test, the wetness control index is tested using a density compaction wetness measuring device for the phosphogypsum modified material;

[0161] The device for measuring density, compaction and moisture content of phosphogypsum modified materials comprises a pressure-bearing structure 2-1, a contact pressing block 2-2 and a cylindrical forming mold 2-9;

[0162] The top and bottom of the cylindrical forming mold 2-9 are both installed with contact pressure blocks 2-2, and the side of the contact pressure blocks 2-2 away from the cylindrical forming mold 2-9 is installed with a pressure-bearing structure 2-1;

[0163] A scale line 2-3 is provided on the contact pressure block 2-2;

[0164] There is also a scale alarm 2-4 on the contact pressure block 2-2; when the edge of the cylindrical forming mold 2-9 is flush with the scale line 2-3 at 0 cm, the scale alarm 2-4 sounds an alarm;

[0165] Four immersion humidity test tubes 2-5 are symmetrically arranged around the contact block 2-2. The immersion humidity test tubes 2-5 pass through the contact block 2-2, with one side extending out of the contact block 2-2 and the other side directly contacting the phosphogypsum modified material in the cylindrical forming mold 2-9.

[0166] A filter screen 2-6 is provided at the bottom of the humidity test tube 2-5, and a water-absorbing and color-changing desiccant 2-8 is provided inside;

[0167] A wetness observation line 2-7 is provided on the wetness test tube 2-5.

[0168] A stirring chamber 1-8 is mounted on the support base 1-13 via a fixture 1-14;

[0169] Double S-shaped stirring blades are symmetrically welded to the high-speed rotating shaft 1-3 in the stirring chamber 1-8, and the full-axis densely distributed crushing rod stirring blades 1-5 are welded to the high-speed rotating shaft 1-3 around a circle; it also includes a stirring time controller 1-9, a stirring speed controller 1-10, a start-stop controller 1-11 and an emergency stop button 1-12;

[0170] Stirring time controllers 1-9 are used to control the stirring time;

[0171] Stirring speed controller 1-10 is used to control the stirring speed;

[0172] The start-stop controller 1-11 is used to control the start and stop of the motor 1-1 when the motor 1-1 is powered on;

[0173] The emergency stop button 1-12 is used to control the power on and off of the motor 1-1.

[0174] The scale line 2-3 on one side of the contact pressure block 2-2 close to the pressure-bearing structure 2-1 is 0 cm, and the scale line 2-3 on the other side is 5 cm;

[0175] The 0 cm scale of the wetness observation line 2-7 is flush with the side of the contact pressure block 2-2 close to the pressure-bearing structure 2-1, and a 1 cm scale range is set upward. Example 5

[0176] The invention points that require key protection mainly include three major aspects: the first is the new modifier material; the second is the high-speed, high-efficiency crushing and uniform stirring method and device; and the third is the creatively proposed method and device for controlling the compaction degree by impregnation. The specific invention points are as follows:

[0177] (1) The present invention creatively proposes a new type of modifier material. The biggest difference between the present invention and cement-based curing materials is that the material has high early strength. Considering the comprehensive economic performance to meet the engineering requirements (compared with the existing highway base materials, the comprehensive engineering cost is not increased), the present invention not only meets the requirements of the seven-day unconfined compressive strength of the highway base (generally controlled at 5 MPa), but also has a large increase in strength in the later stage, strong water stability, good volume stability, no expansion and cracking, and is environmentally friendly.

[0178] The main materials of the new modifier are calcium oxide (CaO), silicon dioxide (SiO2), aluminum oxide (Al2O3), ferric oxide (Fe2O3), mineral powder, tricalcium silicate (3CaO·SiO2), calcium carbonate (CaCO3), sodium silicate (Na2O·nSiO2), coupling agent, iron powder, and rubber powder, with a fineness of not less than 1000 mesh. The new modifier uses the principle of stimulating phosphogypsum (the main component of which is calcium sulfate dihydrate (CaSO4·2H2O)) to cause it to undergo a petrification reaction, producing a basalt-like texture. Iron powder is also added to control the growth of early strength, and rubber powder is compounded to fill the pores within the phosphogypsum. Since the microscopic morphology of phosphogypsum itself presents a plate-like crystal arrangement and a large internal porosity, the use of rubber powder can fill its internal pores, enhancing the strength and stability of the phosphogypsum material. In addition, rubber powder itself has certain elastic properties. The addition of rubber powder can effectively enhance the elastic properties of the phosphogypsum-modified material, prevent the phosphogypsum-modified material from shrinking and expanding and cracking, and improve the performance of the phosphogypsum-modified material.

[0179] The production ratio of phosphogypsum curing materials generally requires that the mass ratio of the phosphogypsum material itself is not less than 80%, and its mass can be controlled between 80% and 90%. The mass of the new modifier material is controlled between 10% and 20%. The mass of water is 15% to 18% of the total amount of phosphogypsum and the new modifier. Since phosphogypsum materials are highly sensitive to water, too high a water content will lead to a decrease in the compaction degree of phosphogypsum, while too low a water content will lead to poor excitation effect of the phosphogypsum material, which is not conducive to the curing of phosphogypsum. Therefore, in actual projects, the water content should be strictly controlled. Water should not be used excessively or too little. The water content should be controlled at 15% to 18% of the total amount of phosphogypsum and modifier.

[0180] The following is the phosphogypsum curing mix ratio with better engineering application effect:

[0181] Mix ratio 1: phosphogypsum: modifier = 10:90, water content is 15% of the total amount of phosphogypsum and modifier;

[0182] Mix ratio 2: phosphogypsum: modifier = 15:85, water content is 16% of the total amount of phosphogypsum and modifier;

[0183] Mix ratio 3: phosphogypsum: modifier = 17:83, the water content is 17% of the total amount of phosphogypsum and modifier.

[0184] Mix ratio 4: phosphogypsum: modifier = 20:80, the water content is 18% of the total amount of phosphogypsum and modifier.

[0185] (2) The present invention proposes a high-speed (generally requiring a rotation speed of not less than 500 r / min), high-efficiency, crushing-type uniform mixing method and device, which makes up for the shortcomings of the traditional mixing method of low speed, no crushing, and uneven mixing. It combines high-speed rotation with double S composite full-axis dense crushing rod-type mixing blades to solve the problem of internal agglomeration of phosphogypsum materials. In addition, under the creative mixing method of combining high-speed rotation with dense rod-type crushing mixing blades, the phosphogypsum material is mixed with the added modifier and water more evenly, which is conducive to the improvement and stabilization of various comprehensive properties of the phosphogypsum material after solidification, especially its strength and volume stability are greatly improved.

[0186] Combine Figure 1 and Figure 2 , the invention double S composite full-axis densely distributed crushing rod type stirring device is described as follows, its main parts are divided into: 1-1 electric motor, 1-2 high-speed rotating machine, 1-3 high-speed rotating shaft, 1-4 double S stirring blades, 1-5 full-axis densely distributed crushing rod type stirring blades, 1-6 feed and discharge ports, 1-7 fixed cover, 1-8 stirring chamber, 1-9 stirring time controller, 1-10 stirring speed controller, 1-11 start and stop controller, 1-12 emergency stop button, 1-13 support base, 1-14 fixer.

[0187] The motor 1-1 is used to provide a power source for the high-speed rotating machine 1-2. It is a variable frequency configuration and can control the rotation speed by adjusting the frequency as needed.

[0188] The high-speed rotating machine 1-2 is used to provide high-speed rotation function, has sufficient strength and rigidity, and can operate stably under high-speed rotation conditions. Its rotation speed is required to reach 500r / min, and the speed can be controlled by adjustment.

[0189] The high-speed rotating shaft 1-3 is used to connect the high-speed rotating machine 1-2 and the mixing blades, transmit the high-speed rotating function of the high-speed rotating machine 1-2 to the mixing blades, drive the double S mixing blades 1-4 and the full-axis densely distributed crushing rod type mixing blades 1-5 to generate high-speed rotation function, have sufficient strength and rigidity, and operate stably under high-speed rotation conditions.

[0190] The double S-type stirring blades 1-4 are used to stir the phosphogypsum material, causing the phosphogypsum material to circulate in the longitudinal direction and circulate left and right in the horizontal direction, thereby achieving uniform stirring in the horizontal direction. The double S-type stirring blades 1-4 have sufficient strength and rigidity and can operate stably under high-speed rotation conditions.

[0191] The entire shaft is densely distributed with breaker bar-type stirring blades (1-5) to stir the phosphogypsum material and break up any lumps, ensuring a more uniform mixing of the phosphogypsum. Leveraging the force of high-speed rotation, these breaker bar-type stirring blades break up any lumps in the phosphogypsum, ensuring a more uniform mixing of the phosphogypsum, modifier, and water, improving the overall performance of the phosphogypsum-modified material. The machine possesses sufficient strength and rigidity to ensure stable operation even at high speeds.

[0192] Feed and discharge ports 1-6 are used to add phosphogypsum, modifier and water into the mixing chamber, and are also used to discharge the mixed material after uniform mixing. They are generally square in structure and have reasonable size to meet the requirements of feeding and discharging.

[0193] The fixed cover 1-7 is used to seal the feed and discharge ports 1-6. The fixed cover is opened when adding materials and closed when mixing to prevent dust and accidents during mixing. It has sufficient strength and rigidity to seal the feed and discharge ports tightly.

[0194] The stirring chamber 1-8 is used to hold phosphogypsum, modifier and water, provide space for stirring the mixed materials, meet the stirring requirements of the mixed materials, have sufficient strength and rigidity, and operate stably under high-speed rotation conditions. The stirring chamber is connected to the support base during the stirring process and is fixed. When the stirring is completed, the fixed valve can be loosened and the stirring chamber can be rotated to realize the discharge of the mixed material.

[0195] The mixing time controller 1-9 is used to control the mixing time of the phosphogypsum mixture, which can achieve continuous control and is generally controlled to 90~120s.

[0196] Stirring speed controllers 1-10 are used to control the stirring speed of the phosphogypsum mixture. They can achieve stepless speed regulation, i.e., they can be adjusted from 0 to the maximum speed. During the stirring process of the phosphogypsum mixture, high-speed rotation is required, and the control speed should not be less than 500r / min.

[0197] Start-stop controller 1-11 is used to control the start and stop of the mixing device.

[0198] Emergency stop buttons 1-12 are used to stop all operations of the stirring device in an emergency.

[0199] The support base 1-13 is used to support the entire stirring device and has sufficient strength and rigidity to operate stably under high-speed rotation conditions without moving.

[0200] The fixer 1-14 is used to fix the stirring chamber 1-8 and the support base 1-13 together to ensure that the stirring chamber does not rotate during high-speed stirring and has sufficient strength and rigidity.

[0201] (3) The present invention creatively proposes a new compaction control standard and device for phosphogypsum modified materials, which solves the problem of poor solidification quality of phosphogypsum caused by the current reliance on compaction density to control compaction. On the basis of meeting the original compaction density control index (i.e. not less than the original compaction), the present invention adds a wetness control index for the phosphogypsum-modifier-water composite material. That is, after adding the modifier and water to the phosphogypsum material, the composite material is formed and its internal water is squeezed out during the indoor compaction process. When the squeezed-out water is soaked to the specified scale, it indicates that the compaction meets the engineering requirements. At this time, the solidification and stability of the phosphogypsum material can achieve the best effect. If too much water flows out, too little water flows out, or even no water flows out, it means that the wetness is too large or too small, and the best effect of the strength index and stability index after solidification of the phosphogypsum cannot be achieved. During on-site compaction of phosphogypsum-modifier-water composite materials, the inventive moisture content control method proposed in this invention achieves both the desired compaction and the required moisture content for phosphogypsum solidification. This avoids the drawback of solely using density and compaction as a control metric while ignoring the required moisture content. Instead, the dual control metric of density, compaction, and moisture content addresses both the density and hydration requirements of the phosphogypsum material, effectively improving various performance indicators of the solidified phosphogypsum. When dual control criteria are used, moisture content generally increases the overall compaction value, resulting in overpressure (exceeding the specified compaction). This beneficial effect on the phosphogypsum base layer is attributed to the heavy-duty rollers used on-site. From an overall performance perspective, the increased compaction can appropriately reduce the amount of modifier material, while still meeting the strength and stability requirements of the phosphogypsum highway base layer, thereby saving overall construction costs.

[0202] Combined with attachment Figure 3 The invention of the density compaction and moisture content measuring device for phosphogypsum modified materials is described as follows, and its main parts are divided into: 2-1 pressure-bearing structure, 2-2 contact pressure block, 2-3 scale line, 2-4 scale alarm, 2-5 moisture content test tube, 2-6 filter screen, 2-7 moisture content observation line, 2-8 water-absorbing and color-changing desiccant, and 2-9 cylindrical forming mold.

[0203] The pressure-bearing structure 2-1 is used to directly contact the pressure applied by the press, is connected to the contact pressure block 2-2, and transmits the pressure to the contact pressure block 2-2 to achieve compaction of the phosphogypsum material. Its upper part is a circular block and the lower part is a cylindrical block, forming a "T" structure. The pressure-bearing structure is higher than the contact pressure block by a certain distance, leaving enough height space for the immersion humidity test tube to operate. It has sufficient strength and rigidity and does not deform under heavy pressure.

[0204] Contact block 2-2 is connected to pressure-bearing structure 2-1 and directly contacts the uniformly mixed mixture of phosphogypsum, modifier, and water. Pressure is applied to compact the mixture to the specified density. Scale lines 2-3 are provided on the left and right sides of the contact block to control the vertical displacement of the block. Four immersion test tubes 2-5 are positioned around contact block 2-2. These test tubes extend through contact block 2-2, with one side extending a certain height from contact block 2-2 and the other side in direct contact with the phosphogypsum mixture. A filter screen 2-6 is provided at the bottom to prevent the phosphogypsum mixture from entering the test tubes.

[0205] Scale lines 2-3 are used to indicate the vertical displacement values required for contact block 2-2 to be pressed into the phosphogypsum mixture and to control the depth to which contact block 2-2 is pressed into the phosphogypsum mixture. The scale lines are 5 cm in length and are subdivided into millimeter increments. The top of contact block 2-2 (the side not directly contacting the phosphogypsum mixture) is marked as the 0 mark, the bottom of the contact block (the side directly contacting the phosphogypsum mixture) is marked as the 5 cm mark, and the intermediate marks are set from 0 to 5 cm according to a standard scale. This scale line arrangement is beneficial in that it allows for easy reading of the depth to which the contact block should be pressed into the phosphogypsum mixture and facilitates control of the vertical displacement of the contact block.

[0206] Scale alarm 2-4 is used to provide an alarm for vertical displacement. When the contact block moves to the specified scale, that is, when the edge of the cylindrical forming mold 2-9 touches the top of the scale line 2-3 (on the side not directly contacting the phosphogypsum mixture), scale alarm 2-4 sounds an alarm, indicating that the test vertical displacement has reached the specified value. Because the contact block 2-2 is divided into two parts, upper and lower, which are placed into the cylindrical forming mold at the same time and compaction is carried out simultaneously, the scale alarm 2-4 is also divided into two parts, upper and lower. The scale alarms 2-4 in the upper and lower parts are connected. If only the upper or lower alarm sounds, the compaction process can continue. When the alarms in both parts sound, it indicates that the compaction test has reached the specified vertical displacement value and the test should be stopped.

[0207] The moisture content test tube 2-5 is used to measure the moisture content of the phosphogypsum mixture during compaction, thereby determining the compaction degree and the desired moisture content for curing. It is filled with a color-changing desiccant, and a filter 2-6 is installed at the bottom (the side directly contacting the phosphogypsum mixture) to prevent the phosphogypsum mixture from entering the test tube. One side of the moisture content test tube 2-5 is in direct contact with the phosphogypsum mixture, while the other side passes through the contact block 2-2 and extends a certain height beyond the contact block 2-2. A 1cm effective observation scale is set, with the 0 mark at the bottom, flush with the top surface of the contact block 2-2 (the side not in direct contact with the phosphogypsum mixture), and the 1cm mark at the top. Intermediate marks follow a standard scale, set to the millimeter level. During the compaction process, when the color-changing desiccant in the immersion moisture test tube 2-5 absorbs the squeezed water in the phosphogypsum mixture and changes color, and reaches the 5mm scale value position of the immersion moisture test tube 2-5 scale line, it means that its immersion moisture reaches the best effect, that is, the moisture control effect in the phosphogypsum mixture is the best. When the color-changing height of the desiccant is lower than the 0 scale line of the immersion moisture test tube, it means that the moisture control in the phosphogypsum mixture is low. When the color-changing height of the desiccant is higher than the 1cm scale line of the immersion moisture test tube, it means that the moisture control in the phosphogypsum mixture is high. Both lower and higher moisture control amounts will affect the performance of the phosphogypsum mixture. In the engineering application process, the height of the desiccant absorbing the squeezed water in the phosphogypsum mixture and causing the color change is controlled within the range of 0-1cm of the immersion moisture test tube, so that the strength and stability of the compacted phosphogypsum mixture are better.

[0208] The filter 2-6, as the bottom structure of the immersion moisture test tube, is used to prevent the phosphogypsum mixture from pouring into the immersion moisture test tube, allowing moisture to flow into the immersion moisture test tube and having sufficient anti-deformation ability.

[0209] The moisture content observation line 2-7, the primary observation portion of the moisture content test tube, is used to measure the height at which the desiccant changes color upon absorbing moisture, thereby controlling the compaction degree and curing water requirement of the phosphogypsum mixture. The moisture content observation line has an effective observation length of 1 cm, with the 0 mark at the bottom, flush with the top surface of contact block 2-2 (the side not in direct contact with the phosphogypsum mixture), and the 1 cm mark at the top. Intermediate marks are set according to a standard scale, down to the millimeter level.

[0210] Water-absorbing color-changing desiccant 2-8 is used to absorb the moisture squeezed out of the phosphogypsum mixture during the compaction process. The water-absorbing color-changing desiccant is generally a silica gel desiccant, the main component of which is amorphous silicon dioxide, a highly adsorbent material. It is blue before absorbing water and red after absorbing water. The water content in the phosphogypsum mixture can be judged by the color change after water absorption, thereby judging the quality of the performance of the phosphogypsum after solidification.

[0211] Cylindrical forming mold 2-9, used for holding and compacting the phosphogypsum mixture, is hollow and uncovered. The contact block used in the phosphogypsum modified material density compaction and moisture content measurement device fits neatly into the cylindrical forming mold. The phosphogypsum mixture is filled into the cylindrical forming mold and, under a certain pressure, formed into a specimen of specified dimensions (typically a cylindrical specimen with dimensions of 100 mm φ and 100 mm height), exhibiting sufficient strength and rigidity.

[0212] The implementation of the present invention is divided into three steps: batching, mixing, and compacting. First, the batching mainly involves the mix ratio of phosphogypsum, modifier, and water. A certain mass of phosphogypsum, modifier, and water are weighed according to the designed mix ratio. A new modifier is used. These are weighed and set aside. The batching is complete.

[0213] Securely secure the double-S composite, fully-shafted, densely distributed, crushed-rod-type stirring device to the ground using support base 1-13. Use fixture 1-14 to secure stirring chamber 1-8 in a stable position to prevent rotation. Open feed and discharge ports 1-6 and sequentially add the weighed phosphogypsum, modifier, and water into stirring chamber 1-8. Seal feed and discharge ports 1-6 with fixed cap 1-7. Set the desired stirring time and speed using stirring time controller 1-9 and stirring speed controller 1-10, respectively. Press start / stop controller 1-11 to activate the double-S composite, fully-shafted, densely distributed, crushed-rod-type stirring device. The motor 1-1, high-speed rotor 1-2, and high-speed rotating shaft 1-3 drive the double-S stirring blades 1-4 and fully-shafted, densely distributed, crushed-rod-type stirring blades 1-5 to begin stirring the mixture of phosphogypsum, modifier, and water. In an emergency, press emergency stop button 1-12 to halt all device operations. Once stirring is complete, shut down the stirring device using start / stop controller 1-11.

[0214] The evenly stirred phosphogypsum mixture is taken out from the double-S composite full-shaft densely distributed crushing rod stirring device and placed in a container of a certain capacity for easy loading. According to the predetermined compaction degree, the design value of the molding sample and the volume of the cylindrical molding mold 2-9, the phosphogypsum mixture is calculated and weighed, the phosphogypsum modified material density compaction-wetness measurement device is turned upside down to a fixed surface, and the cylindrical molding mold 2-9 is placed on the contact pressure block 2-2 of the phosphogypsum modified material density compaction-wetness measurement device as the base of the cylindrical molding mold 2-9, and the phosphogypsum mixture is layered into the cylindrical molding mold 2-9, generally in three layers. The phosphogypsum mixture to be loaded into the cylindrical molding mold 2-9 is divided into three equal parts and loaded into the mold in turn. After each layer is loaded, it is gently and evenly tamped with a tamping rod; during the loading process, the tamping rod is used manually to tamp clockwise. After tamping, the contact pressure block 2-2 is placed above the cylindrical molding mold 2-9 and placed on the press as a whole. The total vertical displacement of the upper and lower contact pressure blocks 2-2 that need to be pressed in is read through the scale line 2-3 and used as the preset displacement of the press. Compaction of the phosphogypsum mixture begins using the pressure-bearing structure 2-1 and contact block 2-2. When either of the upper and lower scale alarms 2-4 sounds, observe the compaction process and continue compacting. When both alarms sound simultaneously, contact block 2-2 has reached its preset displacement value, and compaction should cease. The position of the water-absorbing, color-changing desiccant 2-8 is observed through the moisture observation line 2-7 of the moisture-absorbing test tube 2-5, indicating the amount of moisture expelled from the phosphogypsum mixture. Because a bottom filter 2-6 is located at the bottom of the moisture-absorbing test tube (the portion directly in contact with the phosphogypsum mixture), preventing the phosphogypsum mixture from entering the moisture-absorbing test tube 2-5, the water-absorbing, color-changing desiccant 2-8 indicates the amount of moisture expelled, thereby determining whether the appropriate amount of moisture has been added to the phosphogypsum mixture. This achieves the dual control of density, compaction, and moisture-absorbing properties for the compaction and curing quality of the phosphogypsum mixture. After compaction is completed, the cylindrical forming mold 2-9, the contact pressing block 2-2, and the pressure-bearing structure 2-1 are placed at room temperature for 6 hours, and then demoulded and subjected to standard curing.

[0215] The technical solution of the present invention is adopted, that is, phosphogypsum and the modifier are mixed under the action of water, and the stirring method and device provided by the present invention are used for mixing. At the same time, the compaction is carried out using the compaction control method proposed in the present invention, and the compaction is controlled by soaking moisture, which achieves good results. The specific test data are shown in Table 1.

[0216] However, the conventional solution, i.e. mixing phosphogypsum with cement-stabilized materials, using ordinary mixing equipment for mixing, and the compaction degree using a mass ratio method generally controlled to the maximum dry density, achieves an effect inferior to that of the solution of the present invention.

[0217] Table 1

[0218]

[0219] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a modified phosphogypsum material for highways under a new excitation system, characterized in that: The modified phosphogypsum material for highways under the new excitation system comprises the following raw materials in percentage by weight: 80% to 90% phosphogypsum, 10% to 20% modifier, totaling 100%; It also includes water, the mass of which is 15% to 18% of the total mass of phosphogypsum and modifier; The modifier includes the following raw materials in parts by weight: 4.8-5.2 parts of calcium oxide, 5.8-6.2 parts of silicon dioxide, 3.9-4.1 parts of aluminum oxide, 9.9-10.1 parts of ferric oxide, 39-41 parts of mineral powder, 29-31 parts of tricalcium silicate, 1.9-2.1 parts of calcium carbonate, 0.9-1.1 parts of sodium silicate, 0.9-1.1 parts of coupling agent, 0.48-0.52 parts of iron powder, and 0.48-0.52 parts of rubber powder; The method for preparing the modified phosphogypsum material for highways under the new excitation system comprises the following steps: Step (1), ingredients: weigh phosphogypsum, modifier and water; Step (2), mixing: stirring the phosphogypsum, modifier and water weighed in step (1) until they are uniformly mixed to obtain a phosphogypsum modified material; wherein the stirring speed is not less than 500 r / min; Step (3), compaction test: the compaction density control index and the wetness control index of the phosphogypsum modified material are tested. If the compaction control index requirement is not less than 98% of the maximum dry density, and the wetness control index is within the range of 5mm~10mm, the test is passed and the material is used in the design of the highway pavement base structure; If the test fails, the batch of materials cannot be used in the design of highway pavement base structure and should be discarded; Step (2), stirring using a double S composite full-shaft densely distributed crushing rod type stirring device, the double S composite full-shaft densely distributed crushing rod type stirring device comprising a support base (1-13); A stirring chamber (1-8) is mounted on the supporting base (1-13); the stirring chamber (1-8) is rotatable relative to the supporting base (1-13); The top of the stirring chamber (1-8) is provided with a feed port and a discharge port (1-6); The feed and discharge ports (1-6) are provided with fixed covers (1-7); It also includes an electric motor (1-1) and a high-speed rotating machine (1-2); The power output end of the electric motor (1-1) is connected to the power input end of the high-speed rotating machine (1-2), providing a power source for the high-speed rotating machine (1-2); The stirring chamber (1-8) is equipped with a high-speed rotating shaft (1-3), the other end of which extends out of the stirring chamber (1-8) and is connected to the power output end of the high-speed rotating machine (1-2); the high-speed rotating machine (1-2) is used to drive the high-speed rotating shaft (1-3) to rotate; A double S-type stirring blade (1-4) and a full-shaft densely distributed crushing rod type stirring blade (1-5) are installed on the high-speed rotating shaft (1-3) inside the stirring chamber (1-8).

2. The method for preparing a modified phosphogypsum material for highways under a new excitation system according to claim 1, characterized in that: The coupling agent used is aluminate coupling agent; the activity index of the mineral powder is required to be no less than 75%; the iron powder is required to be no less than 500 mesh; the purity of the rubber powder is required to be no less than 99% and no less than 500 mesh.

3. The method for preparing a modified phosphogypsum material for highways under a new excitation system according to claim 1, characterized in that: A stirring chamber (1-8) is mounted on the support base (1-13) via a fixture (1-14); The double S-type stirring blades are symmetrically welded on the high-speed rotating shaft (1-3) in the stirring chamber (1-8), and the full-axis densely distributed crushing rod type stirring blades (1-5) are welded on the high-speed rotating shaft (1-3) around the high-speed rotating shaft (1-3).

4. The method for preparing a modified phosphogypsum material for highways under a new excitation system according to claim 1, characterized in that: It also includes a stirring time controller (1-9), a stirring speed controller (1-10), a start-stop controller (1-11) and an emergency stop button (1-12); The stirring time controller (1-9) is used to control the stirring time; The stirring speed controller (1-10) is used to control the stirring speed; The start-stop controller (1-11) is used to control the start and stop of the motor (1-1) when the motor (1-1) is powered on; The emergency stop button (1-12) is used to control the power supply of the motor (1-1).

5. The method for preparing a modified phosphogypsum material for highways under a new excitation system according to claim 1, characterized in that: In step (3) of the compaction test, the wetness control index is tested using a phosphogypsum modified material density compaction wetness measuring device; The device for measuring density, compaction and moisture content of phosphogypsum modified materials comprises a pressure-bearing structure (2-1), a contact pressure block (2-2) and a cylindrical forming die (2-9); The top and bottom of the cylindrical forming mold (2-9) are both installed with contact pressure blocks (2-2), and a pressure-bearing structure (2-1) is installed on the side of the contact pressure blocks (2-2) away from the cylindrical forming mold (2-9); A scale line (2-3) is provided on the contact pressure block (2-2); The contact pressing block (2-2) is also provided with a scale alarm (2-4); when the edge of the cylindrical forming mold (2-9) is flush with the scale line (2-3) at 0 cm, the scale alarm (2-4) will sound an alarm; Four immersion humidity test tubes (2-5) are centrally symmetrically arranged around the contact pressing block (2-2). The immersion humidity test tubes (2-5) penetrate the contact pressing block (2-2), with one side extending out of the contact pressing block (2-2) and the other side directly contacting the phosphogypsum modified material in the cylindrical forming mold (2-9); A filter screen (2-6) is provided at the bottom of the humidity test tube (2-5), and a water-absorbing and color-changing desiccant (2-8) is provided inside. A humidity observation line (2-7) is provided on the humidity test tube (2-5).

6. The method for preparing a modified phosphogypsum material for highways under a new excitation system according to claim 5, characterized in that: The scale line (2-3) on one side of the contact pressure block (2-2) close to the pressure-bearing structure (2-1) is 0 cm, and the scale line (2-3) on the other side is 5 cm; The 0 cm scale of the wetness observation line (2-7) is flush with the side of the contact pressure block (2-2) close to the pressure-bearing structure (2-1), and a 1 cm scale range is set upward.

7. The device for measuring density and compaction wetness of the phosphogypsum modified material according to any one of claims 5 to 6.

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