CN114538872B - A mine restoration ecological concrete based on phosphate rock tailings and its preparation method and application - Google Patents

Abstract

The invention discloses a mine restoration ecological concrete based on phosphorite tailings, which comprises 0.40-0.45 part of phosphogypsum and 2.0-2.2 parts of waste rock aggregate in parts by weight, and also comprises a composite special additive, wherein the composite additive comprises modified hydroxypropyl methyl cellulose ether, a gypsum protein retarder and redispersible rubber powder; the composite additive comprises 65 to 68 weight parts of modified hydroxypropyl methyl cellulose ether, 18 to 20 weight parts of gypsum protein retarder and 14 to 16 weight parts of redispersible rubber powder; the mixing amount of the phosphogypsum-waste stone aggregate is 0.02-0.04 percent of the mass of the phosphogypsum-waste stone aggregate; the mine restoration ecological concrete fully utilizes the phosphogypsum and the waste rock in the phosphate tailings, and solves the problems of poor construction performance and low porosity after molding of the phosphogypsum and the waste rock aggregate directly applied to the ecological concrete by adding the composite additive; local materials are used, so that the phosphorite tailings are treated, and the ecological environment of a mine area is restored.

Description

A mine restoration ecological concrete based on phosphate rock tailings and its preparation method and application

technical field

The invention relates to an ecological concrete, in particular to a mine restoration ecological concrete based on phosphate rock tailings and a preparation method and application thereof.

Background technique

On the one hand, as the main source of phosphate fertilizer production, phosphate rock deeply affects the development of agriculture in our country. At present, more than 90% of phosphate rock is used for the production of phosphate fertilizer, and the tailings are difficult to deal with. On the other hand, phosphate rock is an important chemical mineral raw material, widely used in national defense, manufacturing and other industries. At present, more than 4 million mu of land is occupied and damaged by phosphate mine mining, of which more than 2 million mu is occupied by mines under mining, and more than 2 million mu is occupied by historical mines. Mine restoration is imminent. During the mining process, a large amount of unusable land will be produced without treatment, also known as mining waste land, where there are various pollutions caused by production. Mine restoration refers to the restoration of the pollution of mining wasteland, the restoration of the damaged ecological environment, and the sustainable use of land resources. The problems faced in the restoration of phosphate mines mainly include (1) waste rock accumulation land formed by stripping topsoil, mining rock-type phosphate rock fragments and low-grade ore accumulation; (2) industrial tailings attached to phosphate rock The accumulation is serious, coupled with the abundant rainfall in the southern region, the toxic and harmful components in the tailings are likely to cause secondary pollution.

Phosphate rock tailings are mainly secondary tailings phosphogypsum and direct tailings waste ore. Phosphogypsum hardens rapidly, its fluidity and viscosity are worse than ordinary cement, and its construction performance as a cementitious material is poor. The gradation of the waste ore in the phosphate rock tailings is not fixed, and the natural porosity formed is not high. Layer phenomenon, resulting in unstable quality of ecological concrete, low porosity, cracking after formation of mountain slope protection and other problems.

Contents of the invention

Purpose of the invention: the present invention aims to provide a mine restoration ecological concrete based on phosphate rock tailings, and another purpose of the present invention is to provide the preparation method and application of the ecological concrete.

Technical solution: the vegetation concrete based on phosphate ore tailings of the present invention, the vegetation concrete includes 0.40-0.45 parts of phosphogypsum and 2.0-2.2 parts of waste rock aggregate in parts by weight, and also includes a compound special admixture, and the compound special Admixtures include modified hydroxypropyl methylcellulose ether, gypsum protein retarder and redispersible rubber powder.

Among them, the modified hydroxypropyl methylcellulose ether in the compound special admixture has a dispersing effect, and has a polyamino branched chain structure compared to the unmodified hydroxypropyl methylcellulose ether. A small amount of metal ions such as calcium ions form a chelate with the gypsum protein retarder to form a flocculent precipitate. In this precipitate, the metal ion is further complexed with the amino branch of the modified hydroxypropyl methylcellulose ether. In the case of polyamino branched chains, the modified hydroxypropyl methylcellulose ether-metal ion-gypsum protein retarder forms an effective comb-like network, which wraps on the surface of powdery phosphogypsum to further reduce the water content of phosphogypsum. The chemical reaction rate is increased, the viscosity of the slurry is increased, and it is convenient for the construction of the skeleton pore system in the later stage. The redundant amino branch chains are further chelated with heavy metals such as chromium and lead in phosphogypsum and a small amount of radioactive ions to play a curing role. The modified hydroxypropyl cellulose ether polymer was purchased from Xuzhou Hurong New Material Technology Co., Ltd., product model ZJ0683, product name modified cellulose. The function of redispersible rubber powder is to reduce the force between macromolecules and assist in suspension and water retention.

Preferably, the composite admixture contains 65-68 parts of modified hydroxypropyl methylcellulose ether, 18-20 parts of gypsum protein retarder and 14-16 parts of redispersible rubber powder in parts by weight; The dosage thereof is 0.02% to 0.04% of the total mass of phosphogypsum and waste rock aggregate. If the amount of compound admixture is too small, the slurry will segregate seriously, and the phosphogypsum slurry will sag and crack. If the amount is too high, the viscosity will be too high. The actual operation will lead to secondary water addition, which will seriously affect the quality.

Preferably, the gypsum protein retarder is type I collagen retarder.

Preferably, the particle size of the waste rock aggregate is 20-25 mm. Select the waste rocks from the mine restoration site and carry out preliminary rolling to make the maximum particle size 25mm, screen out aggregates with a particle size of 20-25mm as concrete aggregates, and carry out secondary rolling for the remaining aggregates below 20mm. Make the particle size less than 5mm, and mix it with the natural soil in the construction area as gravel soil for vegetation planting.

The preparation method of ecological concrete for mine restoration based on phosphate rock tailings of the present invention: after mixing phosphogypsum and compound special admixture with water, add waste rock aggregate and stir until uniform, the amount of water added is 20% to 20% of the mass of phosphogypsum 30%. Too much mixing water will lead to slurry segregation, insufficient cementing force in the early stage, cracking in the later stage, and landslide phenomenon in mine repair slope protection after forming; insufficient mixing water will lead to uneven mixing and uneven strength in the early stage, and reverse reaction in the later stage. Alkali dampness, poor growth of vegetation, and lower strength of ecological concrete in the later stage.

Application of the ecological concrete for mine restoration based on phosphate rock tailings of the present invention in mine restoration.

The application of the mine restoration ecological concrete based on phosphate rock tailings in mine restoration includes the following steps:

(1) Repair the slope surface, remove the surface layer of the slope surface and part of the strong weathered surface layer;

(2) Pave the ecological concrete, and maintain it until the gypsum in the ecological concrete is hardened after forming;

(3) Spread gravel soil, sprinkle water to infiltrate; spread the mixture of grass seeds and water retaining agent, sprinkle water to infiltrate; continue to spread gravel soil, sprinkle water to infiltrate;

(4) Cover and maintain until sprouting.

Preferably, in step (3), the gravel soil, grass seeds and water-retaining agent are in parts by weight, 0.7-0.9 part of gravel soil, 0.03-0.08 part of grass seed, and 0.0005-0.0008 part of water-retaining agent. Among them, the gravel soil is composed of waste rock and gravel with a particle size of less than 5mm and the natural soil of the construction site, with a mass ratio of 1:0.4 to 0.45; the grass seeds are coated drought-resistant grass seeds, and the coating contains the soluble substances required for the early development of the grass seeds. Nutrients; water-retaining agent has the function of locking water and preventing soil erosion.

Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) The mine restoration ecological concrete fully utilizes the phosphogypsum and waste rock in the phosphorus tailings, and solves the problem of phosphogypsum and waste rock by adding a composite admixture. Stone aggregate is directly used for the problems of poor construction performance of ecological concrete, poor quality after molding, and low porosity; (2) By adjusting the ratio and dosage of each component in the composite admixture, the ecological concrete’s compressive capacity and porosity The rate meets the requirements of mine restoration; (3) Local materials are used to treat the tailings of phosphate rock and restore the ecological environment in the mining area. The organic combination of tailings treatment and ecological governance fully mobilizes the initiative of the enterprise and reduces the tailings of the enterprise. While reducing the cost of materials, restore the original landform of the mine, so as to truly achieve the goal of "whoever repairs it, who benefits".

Detailed ways

The technical solution of the present invention will be further described below.

Example 1

The ecological concrete for mine restoration based on phosphate rock tailings of the present invention comprises 0.40 parts of phosphogypsum and 2.0 parts of waste rock aggregate in parts by weight, and the dosage of the composite admixture is 0.02% of the mass of the phosphogypsum and waste rock aggregate. Among them, the composite admixture contains 65 parts by weight of modified hydroxypropyl methylcellulose ether, 18 parts by mass fraction of type I collagen retarder and 14 parts by ethylene-vinyl acetate copolymer (redispersible rubber powder) The waste rock aggregate is from the waste rock in the mine restoration site, and the waste rock in the mine restoration site is selected for preliminary rolling, so that the maximum particle size is 25mm, and the aggregate with a particle size of 20-25mm is screened out as the concrete bone. The remaining aggregate below 20mm will be rolled twice to make the particle size less than 5mm, and mixed with the natural soil in the construction area as gravel soil for vegetation planting.

Preparation method: After mixing phosphogypsum and compound special admixture with water, add waste rock aggregate and stir until uniform, the amount of water added is 20% of the mass of phosphogypsum.

application:

(1) The laboratory directly spreads the ecological concrete in the mold, and maintains it for 27 days after forming, and the gypsum in the ecological concrete hardens;

(2) Sprinkle gravel soil with a thickness of 10mm, and infiltrate with water; spread the mixture of coated Bermudagrass seeds and ionic polyacrylamide (water-retaining agent), and infiltrate with water; continue to spread gravel soil with a thickness of 10mm, and infiltrate with water;

(3) Sprout after 60 days of film-covering maintenance;

Wherein, by weight, 0.7 part of gravel soil, 0.03 part of coating bermudagrass seed, 0.0005 part of ionic polyacrylamide (water retaining agent); The mass ratio is 1: 0.4 to mix.

Example 2

The mine restoration ecological concrete based on phosphate rock tailings of the present invention comprises 0.43 parts of phosphogypsum and 2.2 parts of waste rock aggregate in parts by weight, and the dosage of the composite admixture is 0.03% of the mass of the phosphogypsum and waste rock aggregate. Among them, the composite admixture contains 66 parts by weight of modified hydroxypropyl methylcellulose ether, 19.4 parts by mass fraction of type I collagen retarder and 14.6 parts by ethylene-vinyl acetate copolymer (redispersible rubber powder). The waste rock aggregate is from the waste rock in the mine restoration site, and the waste rock in the mine restoration site is preliminarily rolled so that the maximum particle size is 25mm, and the aggregate with a particle size of 20-25mm is screened out as the concrete bone. The remaining aggregate below 20mm will be rolled twice to make the particle size less than 5mm, and mixed with the natural soil in the construction area as gravel soil for vegetation planting.

Preparation method: After mixing phosphogypsum and compound special admixture with water, add waste rock aggregate and stir until uniform, the amount of water added is 25% of the mass of phosphogypsum.

application:

(1) The laboratory directly spreads the ecological concrete in the mold, and maintains it for 27 days after forming, and the gypsum in the ecological concrete hardens;

(2) Sprinkle gravel soil with a thickness of 10mm, sprinkle water to infiltrate; spread the mixture of Bermudagrass coated grass seeds and ionic polyacrylamide (water retaining agent), sprinkle water to infiltrate; continue to spread gravel soil, thickness 10mm, sprinkle water to infiltrate;

(3) Sprout after 60 days of film-covering maintenance;

Wherein, by weight, 0.87 parts of gravel soil, 0.05 part of bermudagrass coated grass seed, 0.0007 part of ionic polyacrylamide (water-retaining agent); gravel soil consists of waste rock gravel and construction local natural soil with a particle size less than 5mm. The mass ratio is 1:0.4 mixed.

Example 3

The ecological concrete for mine restoration based on phosphate rock tailings of the present invention comprises 0.45 parts of phosphogypsum and 2.2 parts of waste rock aggregate in parts by weight, and the dosage of the composite admixture is 0.04% of the mass of the phosphogypsum and waste rock aggregate. Among them, the composite admixture contains 68 parts by weight of modified hydroxypropyl methylcellulose ether, 20 parts by mass fraction of type I collagen retarder and 16 parts by weight of ethylene-vinyl acetate copolymer (redispersible rubber powder). The waste rock aggregate is from the waste rock in the mine restoration site, and the waste rock in the mine restoration site is preliminarily rolled so that the maximum particle size is 25mm, and the aggregate with a particle size of 20-25mm is screened out as the concrete bone. The remaining aggregate below 20mm will be rolled twice to make the particle size less than 5mm, and mixed with the natural soil in the construction area as gravel soil for vegetation planting.

Preparation method: After mixing phosphogypsum and compound special admixture with water, add waste rock aggregate and stir until uniform, the amount of water added is 30% of the mass of phosphogypsum.

application:

(1) The laboratory directly spreads the ecological concrete in the mold, and maintains it for 27 days after forming, and the gypsum in the ecological concrete hardens;

(2) Sprinkle gravel soil with a thickness of 10mm, sprinkle water to infiltrate; spread the mixture of Bermudagrass coated grass seeds and ionic polyacrylamide (water retaining agent), sprinkle water to infiltrate; continue to spread gravel soil, thickness 10mm, sprinkle water to infiltrate;

(3) Sprout after 60 days of film-covering maintenance;

Wherein, by weight, 0.9 part of gravel soil, 0.08 part of bermudagrass coated grass seed, 0.0008 part of ionic polyacrylamide (water-retaining agent); gravel soil consists of waste rock gravel less than 5mm in particle size and construction local natural soil The mass ratio is 1: 0.45 mixed.

Comparative example 1

On the basis of Example 2, no compound admixture is added, and other conditions remain unchanged.

Comparative example 2

On the basis of Example 2, the added amount of the composite admixture was adjusted to be 0.01% of the mass of phosphogypsum and waste rock aggregate.

Comparative example 3

On the basis of Example 2, the added amount of the composite admixture was adjusted to be 0.06% of the mass of phosphogypsum and waste rock aggregate.

Performance Testing

(1) The compressive capacity and porosity of the ecological concrete of Examples 1-3 and Comparative Examples 1-3 were tested. The unconfined compressive strength is used to test the compressive capacity of ecological concrete, and the test instrument is a uniaxial press. The porosity of ecological concrete is tested by the drainage method. The volume of the original water body V _water and the volume of the sample after complete immersion V _total are known. The difference between the two is the sum of the volume of the skeleton concrete and the volume of the non-connected pores, divided by the volume of the specimen mold 15* 15*15, measured porosity.

The test results are shown in Table 1.

Table 1 Ecological concrete performance test results

(2) The planting test is an internode environmental test (simulating the mine restoration engineering environment in the laboratory). The planting experiment is carried out in the mine restoration ecological concrete, and the germination time is obtained. The relative value is the test result and that measured by planting in ordinary soil. The ratio of the height of the grass to the depth of the root system, and the pH and conductivity CT value of the ecological concrete leaching water were tested. The test results are shown in Table 2.

Table 2 Vegetative performance test of ecological concrete for mine restoration

It can be seen from Table 1 that the compressive capacity of the ecological concrete in Examples 1-3 meets the geological disasters caused by the disintegration and weathering of the mine surface, can stabilize the mine excavation surface, and the increase in porosity improves the soil and development space required for later vegetation development. , The connected pores allow the plant root system to spread to the bottom of the ecological concrete in the later stage, so that the slope protection of the mine repair and the excavation surface form an overall force, and the reliability of the slope protection is increased. Example 1 performed the best, with the best compression resistance and pore-forming performance. Comparative example 1 did not add composite admixture, and comparative example 2 added a small amount of composite admixture, both of which showed severe segregation, and it was difficult for the slurry to effectively suspend the gelled substance, and the compressive capacity and porosity after final molding were relatively low. Poor, cannot be applied. Comparative Example 3 Due to the high dosage, the viscosity of the slurry is too high, it is difficult to mix, and the construction applicability is not strong.

As can be seen from Table 2, the germination time, germination rate, relative grass height, and root system depth of Examples 1 to 3 Bermudagrass seeds all performed well; the water body pH and conductivity CT values measured by the leaching test were the same as in Example 1. ~3 pH of the water body is suitable for the growth and development of grass seeds, and the low conductivity of the reactive ion concentration means that most of the polluting ions in the phosphate rock tailings are solidified, which meets the purpose of vegetation restoration in mine restoration; the effect of Example 1 is the best . The germination time of Bermudagrass seeds in comparative examples 1 and 2 is long, and the germination rate is extremely low, the relative grass height and root system depth are all extremely low, and the planting effect is poor; Pollution ions have not been solidified, and the effect of ecological restoration has not been achieved. The ecological concrete of comparative example 3 could not be molded, and the vegetation test could not be carried out.

Claims (8)

1. A kind of mine restoration ecological concrete based on phosphate rock tailings, it is characterized in that, described ecological concrete comprises 0.40～0.45 parts of phosphogypsum and 2.0～2.2 parts of waste rock aggregates by weight, also includes composite special admixture, The composite special admixture contains 65-68 parts of modified hydroxypropyl methylcellulose ether, 18-20 parts of gypsum protein retarder and 14-16 parts of redispersible rubber powder in parts by weight; The amount is 0.02%~0.04% of the total mass of phosphogypsum and waste rock aggregate; wherein the modified hydroxypropyl methylcellulose ether has a polyamino branched chain structure; the gypsum protein retarder is type I collagen retarder coagulant. 2. The ecological concrete for mine restoration based on phosphate rock tailings according to claim 1, wherein the particle size of the waste rock aggregate is 20-25 mm. 3. A method for preparing ecological concrete for mine restoration based on phosphate rock tailings according to claim 1 or 2, characterized in that, after adding water and mixing the phosphogypsum and the composite special admixture, adding waste rock aggregate and stirring until uniform , the amount of water added is 20% to 30% of the mass of phosphogypsum. 4. An application of the mine restoration ecological concrete based on phosphate rock tailings according to claim 1 or 2 in mine restoration. 5. according to the application of the mine restoration ecological concrete based on phosphate rock tailings in mine restoration according to claim 4, it is characterized in that, comprising the steps: (1) Repair the slope surface, remove the surface layer of the slope surface and part of the strongly weathered surface layer; (2) Pave the ecological concrete, and maintain it until the gypsum in the ecological concrete hardens after forming; (3) Sprinkle gravel soil, sprinkle water to infiltrate; spread the mixture of grass seeds and water retaining agent, sprinkle water to infiltrate; continue to spread gravel soil, sprinkle water to infiltrate; (4) Cover and maintain until sprouting. 6. The application of mine restoration ecological concrete based on phosphate rock tailings in mine restoration according to claim 5, characterized in that, in step (3), gravel soil, grass seeds and water-retaining agent are by weight, gravel soil 0.7~0.9 parts, grass seeds 0.03~0.08 parts, water retaining agent 0.0005~0.0008 parts. 7. The application of mine restoration ecological concrete based on phosphate rock tailings in mine restoration according to claim 5, characterized in that, in step (3), the gravel soil is composed of waste rock gravel with a particle size of less than 5 mm It is composed of local natural soil with a mass ratio of 1:0.4~0.45. 8. The application of mine restoration ecological concrete based on phosphate rock tailings in mine restoration according to claim 5, characterized in that, in step (3), the grass seeds are coated drought-resistant grass seeds, and the coating Contains soluble nutrients needed for the early development of grass seeds.