阅读说明：本技术 含高硅铁尾矿的混凝土掺合料及其制备方法 (Concrete admixture containing high-silicon iron tailings and preparation method thereof ) 是由 张延年 刘柏男 顾晓薇 宋岩升 于 2021-01-22 设计创作，主要内容包括：本发明公布了含高硅铁尾矿的混凝土掺合料及其制备方法,采用高硅铁尾矿、煤矸石、钢渣、化学活化剂、聚羧酸高效减水剂、抑制剂为原料。因此能够大量消耗工业废弃物。其中高硅铁尾矿、煤矸石、钢渣具备高含量的二氧化硅、氧化铝、氧化钙,具备潜在火山灰活性。本发明通过煅烧急冷,机械研磨,化学激发的手段将高硅铁尾矿、煤矸石、钢渣由非活性晶体转变为具备火山灰活性的玻璃体。其中化学活化剂中的氢氧化钠与偏硅酸钠可以激发其火山灰活性,并且参与水泥的二次水化,生成C-S-H、C-A-H凝胶,提高强度,并且本发明制备的掺合料水化热较低,适合现场浇筑与泵送。(The invention discloses a concrete admixture containing high-silicon iron tailings and a preparation method thereof. Thus, industrial waste can be consumed in large quantities. The high-silicon iron tailings, the coal gangue and the steel slag have high content of silicon dioxide, aluminum oxide and calcium oxide and have potential pozzolanic activity. The invention converts the high-silicon iron tailings, coal gangue and steel slag from inactive crystals into glass bodies with volcanic ash activity by means of calcination quenching, mechanical grinding and chemical excitation. The sodium hydroxide and the sodium metasilicate in the chemical activating agent can excite the pozzolanic activity of the admixture, participate in secondary hydration of cement to generate C-S-H, C-A-H gel and improve the strength, and the admixture prepared by the invention has low hydration heat and is suitable for cast-in-place and pumping.)

1. The concrete admixture containing the high-silicon iron tailings is characterized by comprising the following raw materials in parts by weight: 30-80 parts of high-silicon iron tailings, 10-20 parts of coal gangue, 10-20 parts of steel slag, 10-15 parts of water, 2-3 parts of chemical activating agent, 0.5-1.2 parts of water reducing agent, 0.5-1.2 parts of grinding aid and 0.1-0.2 part of inhibitor.

2. The concrete admixture containing high-silicon iron tailings as claimed in claim 1, wherein the chemical activating agent comprises the following raw materials in parts by weight: 1.5-2.5 parts of solid sodium metasilicate and 0.5 part of solid sodium hydroxide.

3. The concrete admixture containing high-silicon iron tailings as claimed in claim 1, wherein: the inhibitor is sodium citrate.

4. The concrete admixture containing high-silicon iron tailings as claimed in claim 1, wherein the grinding aid is desulfurized gypsum.

5. The admixture for concrete containing high-silicon iron tailings as claimed in claim 1, wherein the water reducing agent is a polycarboxylic acid high-efficiency water reducing agent.

6. A method for preparing the concrete admixture containing high-silicon iron tailings as claimed in any one of the claims 1 to 5, which is characterized by comprising the following steps:

(1) putting the high-silicon iron tailings, the coal gangue, the steel slag and the inhibitor into a calcining furnace, calcining for 2 hours at the temperature of 600-800 ℃, and quenching;

(2) crushing the mixture quenched in the step (1), screening, and mechanically grinding the mixture with the particle size of 0.3-0.9 mm;

(3) and (3) mixing the mixture sieved in the step (2) with the chemical activating agent, the grinding aid, the water reducing agent and water in parts by weight, putting the mixture into a ball mill for 1.5-2 hours, and milling the mixture.

7. The method for preparing a concrete admixture containing high-silicon iron tailings according to claim 6, wherein in the step (2): mechanically grinding the mixture with the particle size of 0.3-0.9mm to the specific surface area D90 value of 350-400m²/kg。

Technical Field

The invention relates to a concrete admixture, in particular to a concrete admixture containing high-silicon iron tailings and a preparation method thereof.

Background

At present, 20-50% of admixture is generally used in concrete to replace cement. The concrete admixture mainly comprises high-quality slag powder and fly ash, and also comprises a small amount of silica fume, limestone powder and zeolite powder. In recent years, with the rapid development of the premixed concrete industry in China, the yield of the premixed concrete in China reaches 155412.74 ten thousand cubic meters in 2014, if the content of the admixture in the concrete is 30%, the consumption of the admixture in the concrete in the year is about 2 hundred million tons, and the number also increases year by year, so that the shortage of the slag powder and the fly ash as the concrete admixture is caused, and the prices of the slag powder and the fly ash are further increased continuously. In addition, with the increasing awareness of environmental protection and the implementation of carbon emission tax, the proportion of thermal power generation in energy structures is also gradually reduced, the emission of fly ash in power plants is expected to be obviously reduced, and in contradiction, the demand of concrete is still increased at a speed of about 5%.

Aiming at the phenomenon that the fly ash and mineral powder of high-quality admixture are greatly in shortage and the problems of resources and environment caused by a large amount of waste iron tailings, the invention takes the iron tailings as a base material and takes industrial waste residue, coal gangue and steel slag as auxiliary materials to prepare the concrete composite admixture. The iron tailings are used to the maximum extent to produce the concrete which is as good as the concrete mixed with high-quality fly ash and mineral powder.

Disclosure of Invention

The invention aims to provide a concrete admixture containing high-silicon iron tailings and a preparation method thereof. The admixture mainly takes iron tailings as a base material, takes industrial waste residue, coal gangue and steel slag as auxiliary materials, combines an inhibitor, a grinding aid and a water reducing agent, and improves the performance of the admixture. The use amount of mineral admixtures such as fly ash and slag can be greatly reduced, industrial waste residues such as iron tailings are consumed, tailing accumulation is reduced, and industrialization of solid waste resources is realized.

In order to solve the problems in the prior art, the technical scheme adopted by the invention is as follows:

the concrete admixture containing the high-silicon iron tailings comprises the following raw materials in parts by weight: 30-80 parts of high-silicon iron tailings, 10-20 parts of coal gangue, 10-20 parts of steel slag, 10-15 parts of water, 2-3 parts of chemical activating agent, 0.5-1.2 parts of water reducing agent, 0.5-1.2 parts of grinding aid and 0.1-0.2 part of inhibitor.

Further, the chemical activator comprises the following raw materials in parts by weight: 1.5-2.5 parts of solid sodium metasilicate and 0.5 part of solid sodium hydroxide.

Further, the inhibitor is sodium citrate.

Further, the grinding aid is desulfurized gypsum.

Further, the water reducing agent is a polycarboxylic acid high-efficiency water reducing agent.

The method for preparing the concrete admixture containing the high-silicon iron tailings comprises the following steps:

(1) putting the high-silicon iron tailings, the coal gangue, the steel slag and the inhibitor into a calcining furnace, calcining for 2 hours at the temperature of 600-800 ℃, and quenching;

(2) crushing the mixture quenched in the step (1), screening, and mechanically grinding the mixture with the particle size of 0.3-0.9 mm;

(3) and (3) mixing the mixture sieved in the step (2) with the chemical activating agent, the grinding aid, the water reducing agent and water in parts by weight, putting the mixture into a ball mill for 1.5-2 hours, and milling the mixture.

Further, mechanically grinding the mixture with the particle size of 0.3-0.9mm to a specific surface area D90 value of 350-400m²/kg。

The invention has the advantages and beneficial effects that:

the concrete admixture containing the high-silicon iron tailings takes the industrial wastes of the high-silicon iron tailings, the coal gangue, the steel slag, the chemical activating agent, the polycarboxylic acid high-efficiency water reducing agent and the inhibitor as production raw materials, so that a large amount of industrial wastes can be consumed. The high-silicon iron tailings, the coal gangue and the steel slag have high content of silicon dioxide, aluminum oxide and calcium oxide and have potential pozzolanic activity. The invention converts the high-silicon iron tailings, coal gangue and steel slag from inactive crystals into glass bodies with volcanic ash activity by means of calcination quenching, mechanical grinding and chemical excitation. The sodium hydroxide and the sodium metasilicate in the chemical activating agent can excite the pozzolanic activity of the admixture, participate in secondary hydration of cement to generate C-S-H, C-A-H gel and improve the strength, and the admixture prepared by the invention has low hydration heat and is suitable for cast-in-place and pumping.

Detailed Description

The present invention is described in detail below with reference to examples:

example 1:

the concrete admixture containing the high-silicon iron tailings comprises the following raw materials by weight: 30 tons of high silicon iron tailings, 20 tons of coal gangue, 20 tons of steel slag, 15 tons of water, 3 tons of chemical activating agent, 1.2 tons of water reducing agent, 1.2 tons of grinding aid and 0.2 ton of inhibitor.

The high-silicon iron tailings, the coal gangue and the steel slag are all industrial wastes. In the embodiment, the high-silicon iron tailings comprise, by mass, 50% -60% of silicon dioxide, 8% -15% of aluminum oxide, 10% -15% of ferric oxide, 8% -15% of calcium oxide, 5% -10% of magnesium oxide, and the balance impurities.

The coal gangue comprises, by mass, 45% -50% of silicon dioxide, 35% -41% of aluminum oxide, 2% -3% of ferric oxide, 1% -3% of calcium oxide, 1% -2% of magnesium oxide, 3% -5% of sulfur trioxide, and the balance of impurities.

The steel slag comprises, by mass, 60-70% of calcium oxide, 10-15% of silicon dioxide, 5-10% of magnesium oxide, 1-3% of ferric oxide, 1-2% of aluminum oxide, 10-15% of weight loss after burning, and the balance of impurities.

The chemical activator comprises the following raw materials by weight: 2.5 tons of solid sodium metasilicate and 0.5 ton of solid sodium hydroxide. The inhibitor is sodium citrate, which can obviously improve the stability of the steel slag. The grinding aid is desulfurized gypsum which can obviously have the fineness of mechanical grinding. Meanwhile, the desulfurized gypsum can also be used as a retarder to prolong the initial setting time. The water reducing agent is a polycarboxylic acid high-efficiency water reducing agent.

The method for preparing the concrete admixture containing the high-silicon iron tailings comprises the following steps:

(1) putting the high-silicon iron tailings, the coal gangue, the steel slag and the inhibitor into a calcining furnace, calcining for 2 hours at the temperature of 600 ℃, and quenching; so that the high-silicon iron tailings, the coal gangue and the steel slag are converted into vitreous bodies.

(2) Crushing the mixture quenched in the step (1), screening, and mechanically grinding the mixture with the particle size of 0.3-0.9 mm; mechanically grinding to a specific surface area D90 value of 350m²/kg。

(3) And (3) mixing the mixture sieved in the step (2) with the chemical activating agent, the grinding aid, the water reducing agent and water in parts by weight, putting the mixture into a ball mill, and milling the mixture for 1.5 hours.

The concrete admixture containing the high-silicon iron tailings fully utilizes the following equation:

xCa(OH)2+SiO2+mH2O＝xCaO.SiO2.mH2O (C-S-H)

yCa(OH)2+Al2O3+nH2O＝yCaO.Al2O3.nH2O (C-A-H)

Na₂SiO₃.9H₂O+Ca(OH)2+nH₂O＝CaO.SiO2.(n+9)H2O+2NaOHCaSO4+2H2O

4CaO.Al2O3.13H2O+CaSO4.2H2O+14H2O＝3CaO.Al2O3.3CaSO4.32H2O+Ca(OH)2。

the concrete admixture prepared in the embodiment replaces cement by 25 percent, and the prepared common C40 concrete is cured for 7d and 28d at the temperature of 20 +/-1 ℃ and the relative humidity of 90 +/-1, and the compressive strength and the flexural strength are as follows:

example 1	Compressive strength	Flexural strength
			7d	32MPa	4.1MPa
28d	43MPa	5.3MPa

Example 2:

this example differs from example 1 in that: the concrete admixture for preparing the high-silicon iron tailings has different raw material contents.

The concrete admixture containing the high-silicon iron tailings comprises the following raw materials by weight: 80 tons of high-silicon iron tailings, 10 tons of coal gangue, 10 tons of steel slag, 10 tons of water, 2 tons of chemical activating agents, 0.5 ton of water reducing agents, 0.5 ton of grinding aids and 0.1 ton of inhibitors.

The chemical activator comprises the following raw materials by weight: 1.5 tons of solid sodium metasilicate and 0.5 ton of solid sodium hydroxide. The rest is the same as example 1.

The difference between the method for preparing the concrete admixture containing the high-silicon iron tailings and the example 1 is that:

in the step (1), the high-silicon iron tailings, the coal gangue, the steel slag and the inhibitor are placed into a calcining furnace to be calcined at the temperature of 800 ℃.

Mechanically grinding the sieved mixture with the particle size of 0.3-0.9mm in the step (2) until the specific surface area D90 value is 400m²/kg。

And (4) grinding time in the step (3) is 2 h. The rest is the same as example 1.

The embodiment improves the proportion of the high-silicon iron tailings. The concrete admixture prepared in the embodiment replaces cement by 35 percent, and the prepared common C40 concrete is cured for 7 days and 28 days at the temperature of 20 +/-1 ℃ and the relative humidity of 90 +/-1, and the compressive strength and the flexural strength of the concrete admixture are slightly lower than those of the concrete admixture prepared in the embodiment 1, but all meet the national standard.

Example 2	Compressive strength	Flexural strength
			7d	31MPa	4.0MPa
28d	40MPa	5.2MPa

Example 3:

this example differs from example 1 in that: the concrete admixture for preparing the high-silicon iron tailings has different raw material contents.

The concrete admixture containing the high-silicon iron tailings comprises the following raw materials by weight: 50 tons of high-silicon iron tailings, 15 tons of coal gangue, 15 tons of steel slag, 12 tons of water, 2.5 tons of chemical activating agents, 1 ton of water reducing agents, 1 ton of grinding aids and 0.15 ton of inhibitors.

The chemical activator comprises the following raw materials by weight: 2 tons of solid sodium metasilicate and 0.5 ton of solid sodium hydroxide. The rest is the same as example 1.

The difference between the method for preparing the concrete admixture containing the high-silicon iron tailings and the example 1 is that:

in the step (1): the high-silicon iron tailings, the coal gangue, the steel slag and the inhibitor are placed into a calcining furnace to be calcined at the temperature of 700 ℃.

Mechanically grinding the screened mixture with the particle size of 0.3-0.9mm in the step (2) until the specific surface area D90 value is 380m²/kg。

The grinding time in the step (3) is 1.7 h. The rest is the same as example 1.

The concrete admixture prepared in the embodiment replaces cement by 28 percent, and the prepared common C40 concrete is cured for 7 days and 28 days at the temperature of 20 +/-1 ℃ and the relative humidity of 90 +/-1, and the compressive strength and the flexural strength of the concrete admixture are slightly higher than those of the concrete admixture prepared in the embodiment 1. The compression strength and the breaking strength are as follows:

example 3	Compressive strength	Flexural strength
			7d	34MPa	4.3MPa
28d	46MPa	5.4MPa