阅读说明：本技术 利用极细钼尾矿的phc管桩用混凝土掺合料和管桩 (Concrete admixture for PHC (prestressed high-strength concrete) tubular pile by utilizing ultra-fine molybdenum tailings and tubular pile ) 是由 耿碧瑶 施士虎 吴世剑 谢盛青 朱维根 于 2021-09-07 设计创作，主要内容包括：本发明公开了一种利用极细钼尾矿的PHC管桩用混凝土掺合料和PHC管桩。所述PHC管桩用混凝土掺合料的制备包括：将极细钼尾矿经压滤或过滤脱水,烘干；将脱硫石膏烘干；将烘干的极细钼尾矿和脱硫石膏,按质量比为(9～10):1配比,并在球磨机中粉磨至物料比表面积为700m～(2)/kg～1000m～(2)/kg,得到所述混凝土掺合料。本发明通过利用极细钼尾矿制备混凝土掺合料,采用该混凝土掺合料来制备PHC管桩,可以提高PHC管桩混凝土的抗压强度,密实度和耐久性,可以降低管桩生产成本,同时可实现钼尾矿和脱硫石膏的资源化利用,具有显著的环境效益和经济效益。(The invention discloses a concrete admixture for a PHC (prestressed high-strength concrete) tubular pile and the PHC tubular pile by using ultra-fine molybdenum tailings. The preparation method of the concrete admixture for the PHC tubular pile comprises the following steps: carrying out filter pressing or filter dehydration on the ultrafine molybdenum tailings, and drying; drying the desulfurized gypsum; mixing the dried ultrafine molybdenum tailings and the desulfurized gypsum according to the mass ratio of (9-10) to 1, and grinding in a ball mill until the specific surface area of the material is 700m 2 /kg～1000m 2 And/kg, obtaining the concrete admixture. According to the invention, the concrete admixture is prepared by using the ultrafine molybdenum tailings, and the PHC tubular pile is prepared by using the concrete admixture, so that the compressive strength, compactness and durability of the PHC tubular pile concrete can be improved, the production cost of the tubular pile can be reduced, the resource utilization of the molybdenum tailings and the desulfurized gypsum can be realized, and the concrete admixture has obvious environmental benefit and economic benefitIt is beneficial to.)

1. The concrete admixture for the PHC tubular pile is characterized in that the concrete admixture for the PHC tubular pile is prepared by mixing dried ultrafine molybdenum tailings and desulfurized gypsum according to a mass ratio of (9-10) to 1, and grinding the mixture in a ball mill until the specific surface area of the material is 700m²/kg～1000m²Obtained in kg.

2. The concrete admixture for PHC tubular piles using ultra-fine molybdenum tailings as claimed in claim 1, wherein,

the dried ultrafine molybdenum tailings are obtained by carrying out filter pressing or filter dehydration on the ultrafine molybdenum tailings until the water content is not higher than 20% and then drying the ultrafine molybdenum tailings by using a dryer;

the content of silicon dioxide in the ultra-fine molybdenum tailings is more than or equal to 70 percent.

3. The concrete admixture for PHC tubular piles using ultra-fine molybdenum tailings as claimed in claim 1, wherein the sulfur trioxide content in the desulfurized gypsum is more than 35%.

4. The concrete admixture for the PHC tubular pile using the ultra-fine molybdenum tailings as recited in claim 1, wherein the concrete admixture is ground by using a co-grinding method, and the grinding time is 15-30 min.

5. The PHC pipe pile utilizing the ultra-fine molybdenum tailings as claimed in claim 1, wherein the ultra-fine molybdenum tailings are molybdenum tailings with 0.5mm screen residue of less than 10%.

6. The PHC tubular pile utilizing the ultrafine molybdenum tailings is characterized by comprising the following raw materials in parts by weight:

wherein the concrete admixture is the concrete admixture for PHC tubular piles using ultra-fine molybdenum tailings as claimed in any one of claims 1 to 5.

7. The PHC pipe pile utilizing the ultrafine molybdenum tailings as claimed in claim 6, wherein the preparation of the PHC pipe pile comprises the following steps: the PHC tubular pile is prepared by mixing the raw materials in parts by weight, uniformly stirring the raw materials by using a forced stirrer, and forming and autoclaving the mixture.

8. The PHC pipe pile utilizing the ultra-fine molybdenum tailings as claimed in claim 6, wherein the compressive strength of the PHC pipe pile is greater than 90 MPa.

Technical Field

The invention relates to the technical field of PHC tubular pile preparation, in particular to a concrete admixture for PHC tubular pile and a tubular pile by using ultra-fine molybdenum tailings.

Background

The prestressed high-strength concrete pipe pile is called PHC pipe pile for short, and is widely applied to engineering buildings such as buildings, traffic, water conservancy and the like, and the compressive strength of the PHC pipe pile concrete is required to be more than 80 MPa. At present, natural quartz powder and the like are generally needed to be used as siliceous raw materials when the PHC tubular pile is prepared, and the cost is high, so that the production cost of the PHC tubular pile is increased. In part of the PHC tubular pile preparation process, the use amount of the slag powder and the fly ash is also larger, and the production cost is increased to a certain extent.

With the development of mining industry, the comprehensive utilization of tailings becomes an important subject of resource utilization and environmental protection. Products using tailings as main raw materials are applied and popularized in various fields, wherein the preparation of building materials by the tailings is one of the main application directions of the tailings. However, because the solid waste generated by rare metal molybdenum has extremely fine tailing particles, the utilization difficulty of the molybdenum tailings is higher at present, and the research and application reports on the preparation of the building material from the molybdenum tailings are less at present.

At present, the compressive strength of the concrete prepared by using molybdenum tailings in the prior art at the age of 28 days is only 70 MPa. Although the resource utilization of the molybdenum tailings is realized to a certain extent, the strength of the prepared concrete cannot meet the requirements of the PHC tubular pile on compressive strength, compactness, durability and the like, and related reports that the ultrafine molybdenum tailings are applied to the production of the PHC tubular pile are not provided in the prior art.

Disclosure of Invention

Based on the above, the invention aims to provide a concrete admixture for a PHC tubular pile and the PHC tubular pile, which utilize ultra-fine molybdenum tailings. The concrete admixture for the PHC tubular pile is prepared by grinding the ultra-fine molybdenum tailings and the desulfurized gypsum, and the PHC tubular pile prepared from the concrete admixture can meet the requirements of the concrete strength and other properties of the PHC tubular pile, save the production cost of the PHC tubular pile, realize the resource utilization of the molybdenum tailings and the desulfurized gypsum, solve the problem of environmental pollution caused by the mass stockpiling of the molybdenum tailings, and have remarkable environmental benefit and economic benefit.

The above purpose of the invention is realized by the following technical scheme:

according to the first aspect of the invention, the concrete admixture for the PHC tubular pile utilizing the ultra-fine molybdenum tailings is prepared by mixing dried ultra-fine molybdenum tailings and desulfurized gypsum according to the mass ratio of (9-10) to 1, and grinding the mixture in a ball mill until the specific surface area of the material is 700m²/kg～1000m²Obtained in kg.

Optionally, the dried ultrafine molybdenum tailings are obtained by performing filter pressing or filtration dehydration on the ultrafine molybdenum tailings until the moisture content is not higher than 20%, and drying the ultrafine molybdenum tailings by using a dryer.

Optionally, the content of silicon dioxide in the ultrafine molybdenum tailings is more than or equal to 70 percent;

optionally, the sulfur trioxide content of the desulfurized gypsum is greater than 35%. The desulfurized gypsum is purchased from thermal power plants.

Optionally, the materials are ground together or ground separately and then mixed and homogenized. Preferably, the powder is ground by adopting a common grinding mode, and the grinding time is 15-30 min.

Optionally, the ultra-fine molybdenum tailings are molybdenum tailings with 0.5mm screen residue < 10%.

According to another aspect of the invention, the PHC tubular pile utilizing ultra-fine molybdenum tailings provided by the invention comprises the following raw materials in parts by weight:

the concrete admixture is the concrete admixture for the PHC tubular pile by utilizing the ultra-fine molybdenum tailings.

Optionally, the preparation of the PHC pile includes: the PHC tubular pile is prepared by mixing the raw materials in parts by weight, uniformly stirring the raw materials by using a forced stirrer, and forming and autoclaving the mixture.

Optionally, the compressive strength of the PHC pile is greater than 90 MPa.

Compared with the prior art, the concrete admixture for the PHC tubular pile with excellent performance is prepared by grinding the ultra-fine molybdenum tailings and the desulfurized gypsum, and the PHC tubular pile is prepared by adopting the concrete admixture for the PHC tubular pile, so that the performances such as concrete strength of the PHC tubular pile are improved, the use of natural quartz powder is avoided, the production cost of the PHC tubular pile is saved, the resource utilization of the molybdenum tailings and the desulfurized gypsum is realized, the problem of environmental pollution caused by the mass stockpiling of the molybdenum tailings is solved, and the concrete admixture has remarkable environmental benefit and economic benefit. In addition, the invention does not need to use fly ash.

The advantages of the invention are mainly embodied in the following aspects:

(1) the invention utilizes the characteristics of fine particles and good grindability of the molybdenum tailings and the desulfurized gypsum, and can prepare the high-performance concrete admixture for the PHC tubular pile only by grinding, thereby having lower production cost.

(2) The content of the ultrafine silicon dioxide in the ultrafine molybdenum tailings ground in the concrete admixture for the PHC tubular pile is high, and the concrete admixture can replace natural quartz powder and partial slag powder or partial cement under the autoclaving process condition for producing the PHC tubular pile, and reacts with calcium hydroxide which is unfavorable for strength in a cementing material to generate tobermorite which contributes to the strength, so that the compactness of the concrete is increased. The desulfurized gypsum can supplement the shortage of sulfate content in the cementing material, thereby promoting the further hydration of silicate in cement, slag and molybdenum tailings. The production cost of the tubular pile can be saved on the premise of not reducing the strength of the PHC tubular pile.

(3) The invention realizes the resource utilization of the molybdenum tailings and the desulfurized gypsum, solves the problem of environmental pollution caused by the mass stockpiling of the molybdenum tailings, and has obvious environmental benefit and economic benefit.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention provides a concrete admixture for PHC tubular piles by using ultrafine molybdenum tailings, which is prepared by mixing dried ultrafine molybdenum tailings and desulfurized gypsum according to the mass ratio of 9: 1-10: 1, and grinding the mixture in a ball mill until the specific surface area of the material is 700m²/kg～1000m²Obtained in kg. Wherein, the grinding can be carried out jointly or respectively for about 15 to 30 minutes, and then the mixture is homogenized. The content of silicon dioxide in the ultra-fine molybdenum tailings is more than or equal to 70 percent. The desulfurization gypsum is purchased from a thermal power plant, and the sulfur trioxide content in the desulfurization gypsum is more than 35%.

The concrete admixture for the PHC tubular pile can be prepared by grinding the ultra-fine molybdenum tailings and the desulfurized gypsum according to the characteristics of fine particles and good grindability. The concrete for the PHC tubular pile has the advantages of high performance and low production cost, realizes resource utilization of molybdenum tailings, and solves the problem of environmental pollution caused by large-scale stockpiling of the molybdenum tailings.

The PHC tubular pile utilizing the ultrafine molybdenum tailings is prepared by replacing natural quartz sand and the like in raw materials with concrete admixture for the PHC tubular pile utilizing the ultrafine molybdenum tailings. According to the PHC tubular pile, the natural quartz sand is replaced by the concrete admixture, so that the compressive strength and other properties of the PHC tubular pile are improved, and the production cost of the PHC tubular pile is saved.

In an alternative embodiment, the preparation of the PHC pile using the ultra-fine molybdenum tailings comprises the following steps:

1) carrying out filter pressing or filter dehydration on the ultrafine molybdenum tailings with the silicon dioxide content of more than or equal to 70 percent until the water content is not more than 20 percent, and drying by using a dryer; wherein the ultrafine molybdenum tailings are fine molybdenum tailings before grinding, namely molybdenum tailings with the screen residue of less than 10% of 0.5 mm.

2) Drying the desulfurized gypsum of the thermal power plant, wherein the content (mass percent) of sulfur trioxide in the desulfurized gypsum is more than 35%;

3) grinding the ultrafine molybdenum tailings obtained by drying in the step 1) and the desulfurized gypsum obtained by drying in the step 2) together for 15-30 minutes or respectively for 15-30 minutes in a ball mill according to the mass ratio of 9: 1-10: 1, and then mixing and homogenizing to ensure that the specific surface area of the material is 700m²/kg～1000m²Obtaining concrete admixture for the PHC pipe pile;

4) replacing natural quartz powder and partial slag powder or partial cement in the existing PHC tubular pile preparation with the concrete admixture for the PHC tubular pile prepared in the step 3), and designing a raw material composition of the PHC tubular pile concrete according to parts by weight. The PHC pipe pile comprises the following raw materials in parts by weight: P.O 42.5 cement: 220-350 parts of a binder; concrete admixture: 70-140 parts; slag powder: 30-90 parts of a solvent; fine aggregate: 650-900 parts of a binder; coarse aggregate: 1000-1300 parts; water: 110-135 parts; polycarboxylic acid water reducing agent: 4-15 parts. Wherein the fine aggregate is natural medium sand; 5-20 mm of the coarse aggregate is crushed; the slag powder is granulated blast furnace slag powder meeting the requirements of S95 level in GB/T18046-2017 granulated blast furnace slag powder for cement, mortar and concrete; the polycarboxylic acid water reducer can be, for example, a polycarboxylic acid water reducer (solid content 20%) meeting the requirement of a standard high-performance water reducer in GB 8076-2008 concrete admixture.

5) The PHC tubular pile can be obtained by uniformly stirring the raw materials by a forced stirrer, forming and autoclaving for curing.

According to the PHC tubular pile, the ultra-fine molybdenum tailings with the silicon dioxide content of more than or equal to 70 percent and the desulfurized gypsum of a thermal power plant are used for preparing the concrete admixture, so that on one hand, high-silicon raw materials are replaced, and the production cost of the tubular pile is reduced; on the other hand, because of the large amount of admixture doped in the gelling system, the gypsum in the cement is diluted, and the desulfurized gypsum supplements the shortage of sulfate content in the gelling system, promotes the hydration of silicate in cement, mineral powder and molybdenum tailings, and improves the strength of the pipe pile concrete.

According to the PHC tubular pile, the molybdenum tailings and the desulfurized gypsum are mixed and ground to 700-100% under low energy consumption by utilizing the good grindability and the fine particle size of the ultrafine molybdenum tailings and the desulfurized gypsum0m²The fineness of/kg can play an active effect and a filling effect in PHC pipe pile concrete, and the compactness, the strength and the durability of the concrete are improved.

The technical solution of the present invention is further described below with reference to specific examples and comparative examples:

example one

In the embodiment, the molybdenum tailings in the terrace ditch are taken, and the molybdenum tailings are subjected to chemical total analysis, wherein the specific analysis result is shown in table 1. Wherein the content of silicon dioxide in the molybdenum tailings is 77.17%.

TABLE 1 sandplateau ditch molybdenum tailings sample chemistry

The PHC tubular pile is prepared by the following steps:

1) feeding the molybdenum tailings in the tailings field into a high-pressure filter press for filter pressing, wherein the water content of a filter cake is 15% -20%, crushing the filter cake by a crusher, and then feeding the crushed filter cake into a dryer for drying;

2) testing the content (mass percentage) of sulfur trioxide in the desulfurization gypsum to be 40.2% by outsourcing thermal power plant desulfurization gypsum, and drying the desulfurization gypsum by using a dryer;

3) feeding the dried molybdenum tailings and the dried desulfurized gypsum into a ball mill according to the mass ratio of 10:1, and jointly grinding the molybdenum tailings and the dried desulfurized gypsum to the specific surface area of 750 +/-50 m²Per kg, obtaining concrete admixture;

4) the PHC tubular pile is produced by using concrete admixture instead of natural quartz powder and part of slag powder according to the concrete mixing ratio shown in the table 2.

Comparative example 1

This comparative example produced PHC piles according to the concrete mix proportions shown in table 2.

The first example and the first comparative example were molded into test blocks of 150mm × 150mm × 150mm, and the compressive strength after autoclaving was as shown in Table 2.

Table 2 comparison of concrete compressive strength of PHC tubular pile in example one and comparative example one

Example two

In the second embodiment, molybdenum tailings of Chengde is used as a raw material, and the molybdenum tailings are subjected to chemical total analysis, and the analysis results are shown in Table 3. Wherein the content of silicon dioxide in the molybdenum tailings is 74.57 percent,

TABLE 3 chemical composition of molybdenum tailings sample from Chengde

The PHC tubular pile is prepared by the following steps:

1) feeding the molybdenum tailings in the tailings field into a high-pressure filter press for filter pressing, wherein the water content of a filter cake is 13% -16%, crushing the filter cake by a crusher, and then drying the filter cake in a dryer;

2) testing the content (mass percentage) of sulfur trioxide in the desulfurization gypsum to be 38.5% by outsourcing thermal power plant desulfurization gypsum, and drying the desulfurization gypsum by using a dryer;

3) feeding the dried molybdenum tailings and the dried desulfurized gypsum into a ball mill according to the mass ratio of 9:1, and jointly grinding the molybdenum tailings and the dried desulfurized gypsum to the specific surface area of 950 +/-50 m²Per kg, obtaining concrete admixture;

4) the PHC tubular pile is produced by using concrete admixture to replace natural quartz powder and part of cement according to the concrete mixing proportion shown in the table 4,

comparative example No. two

This comparative example produced PHC piles according to the concrete mix proportions shown in table 4.

The comparative examples and the comparative examples were molded into test pieces of 150mm × 150mm × 150mm, and the compressive strength ratios after autoclaving are shown in Table 4.

TABLE 4 comparison of concrete compressive strengths of PHC tubular piles in example two and comparative example two

According to the embodiment of the invention, the molybdenum tailings and the desulfurized gypsum are mixed and ground to 700m under low energy consumption by using the good grindability and the fine particle size of the ultrafine molybdenum tailings and the desulfurized gypsum according to the mass ratio of (9-10) to 1²/kg～1000m²The fineness of/kg can play an active effect and a filling effect in the PHC tubular pile concrete, so that the compactness, the strength and the durability of the PHC concrete are improved, wherein the compressive strength reaches over 90MPa, the requirement on the compressive strength of the PHC tubular pile is met, and the PHC tubular pile can adapt to more complex terrains.

The description of the present invention has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to practitioners skilled in this art. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.