CN114605121B - A kind of tungsten tailings autoclaved aerated concrete and its preparation method - Google Patents

Abstract

The invention discloses a tungsten tailings autoclaved aerated concrete and a preparation method thereof, which solves the storage of tungsten tailings in the prior art and directly uses it for the production of autoclaved aerated concrete under low _SiO2 conditions. The technical problem of low strength of autoclaved aerated concrete. It includes 50‑75% sand, 5‑25% quicklime, 10‑30% cementitious material, 0.1‑2% water reducing agent, 1‑5% dihydrate gypsum, 1.1‑5% additive, 0.1‑2% ten Potassium aluminum sulfate dihydrate and 0.1-1% aluminum powder paste, the additive is any one or both of sodium lauryl sulfate and water glass; the sand material includes tungsten tailings and quartz sand, the The mass percentage of tungsten tailings in the sand is 50-100%. The steam pressurized concrete prepared by the present invention, after the addition of tungsten tailings, will also generate a kind of aluminum detobermolite, which further improves the strength of the product, greatly reduces the production cost of steam pressurized concrete, and saves A large number of natural resources can be digested at the same time, and a large amount of tailings can be digested to reduce the environmental load.

Description

A kind of tungsten tailings autoclaved aerated concrete and its preparation method

technical field

The invention relates to the field of steam concrete manufacture, in particular to a tungsten tailings autoclaved aerated concrete and a preparation method thereof.

Background technique

The grade of tungsten ore in our country is low, and the tungsten ore produces a huge amount of tailings during the beneficiation process, with a yield of more than 95%, resulting in a great waste of resources. According to statistics, my country adds more than 1 million tons of tungsten tailings every year. The existing stockpiles of old tungsten tailings dams have exceeded 10 million tons. Tungsten tailings dams have risks such as covering a large area, polluting the ecological environment, endangering human health, and easily causing geological disasters. It is urgent to find a method that can absorb a large amount of tungsten. At the same time, the tailings contain a large number of useful minerals and have not been fully utilized, which not only seriously wastes valuable mineral resources, but also poses a huge challenge to the sustainable development of mines.

Autoclaved aerated concrete is a lightweight concrete made of siliceous materials, such as quartz sand, and calcareous materials, such as cement, gypsum, and lime, by adding aluminum powder to generate hydrogen, and curing under high temperature and high pressure under saturated water vapor. Green building wall material. Autoclaved aerated concrete has the advantages of small bulk density, sound insulation, and heat preservation. As a new type of green building material, it has been vigorously developed in many countries and is widely used in non-load-bearing floor panels and wall panels of various buildings.

At present, the siliceous materials used in the production of autoclaved aerated concrete mainly come from sand, pebbles and gravels in rivers, or sandstone aggregates mined and processed in quartz mines. Due to a large amount of mining, these resources are rapidly depleting; mining these resources not only damages the natural environment and riverbed ecology, but also poses serious challenges to the ecological environment and sustainable development of the place of origin. At the same time, with the further tightening of the state's control over mining resources, not only is the difficulty of obtaining resources increasing year by year, but the cost of raw material procurement has also risen sharply.

However, the existing autoclaved aerated concrete technology requires that the SiO ₂ content of the siliceous material must be greater than 70%, otherwise the strength of the produced product usually does not meet the standard. The _SiO2 content of tungsten tailings is usually low (less than 50% in most cases), which greatly limits the application of tungsten tailings in the production of autoclaved aerated concrete.

Contents of the invention

The object of the present invention is to provide a kind of tungsten tailings autoclaved aerated concrete and preparation method thereof, to solve the stockpiling of tungsten tailings in the prior art, directly use it for the making of autoclaved aerated concrete, low _SiO2 conditions The technical problem of low strength of autoclaved air-entrained concrete.

To achieve the above object, the present invention provides the following technical solutions:

A tungsten tailings autoclaved aerated concrete provided by the present invention comprises the following components in mass percentage: 50-75% sand material, 5-25% quicklime, 10-30% cementitious material, 0.1-2% water reducing agent, 1-5% dihydrate gypsum, 1.1-5% additive, 0.1-2% aluminum potassium sulfate dodecahydrate and 0.1-1% aluminum powder paste, the additive is sodium lauryl sulfate and water glass either or both;

The sand material includes tungsten tailings and quartz sand, the mass percentage of the tungsten tailings in the sand material is 50-100%, the _SiO2 mass fraction of the tungsten tailings is less than ₅₀ %, and the _Al2O3 mass fraction is less than 13%.

Optionally or preferably, the digestion speed of the quicklime is >10 min, the digestion temperature is >50° C., and the calcium oxide content is >60%.

Optionally or preferably, the cementitious material includes any one or both of Portland cement and sulphoaluminate cement.

Optionally or preferably, the water reducer is any one or both of naphthalene-based water reducer and polycarboxylate water reducer.

Optionally or preferably, the SiO ₂ content in the quartz sand is >70%, and the SiO ₂ particle size is 15 μm-75 μm.

Optionally or preferably, the dihydrate gypsum is any one or more of natural gypsum, desulfurized gypsum and phosphogypsum.

Optionally or preferably, the water glass is a sodium silicate solution, the modulus of the sodium silicate solution is >1, and the mass fraction of the sodium silicate solution is >20%.

Optionally or preferably, the active ingredient content in the potassium aluminum sulfate dodecahydrate is >90%, and the pH value is 2.5-6.5.

Optionally or preferably, the active substance content of the sodium lauryl sulfate is greater than 30%, the petroleum ether soluble matter is greater than 1%, and the inorganic salt content is less than 10%.

The preparation method of a kind of tungsten tailings autoclaved aerated concrete provided by the invention comprises the following preparation steps:

S1 Dehydrate and dry the tungsten tailings, grind them finely by ball milling process, and sieve them, and take the part with a particle size of <0.075mm;

S2 adds quicklime, cementitious material, dihydrate gypsum, quartz sand, water in turn, and stirs to make a slurry, and then continues to add aluminum powder paste, sodium lauryl sulfate and potassium aluminum sulfate dodecahydrate to the slurry, so that The ratio of water to material in the slurry is 0.3-0.7, adding water glass and water reducer according to the expansion of the slurry, and then injecting into the mold for pre-curing, followed by cutting, autoclaving and drying to make a finished product.

Based on the above technical solutions, the embodiments of the present invention can produce at least the following technical effects:

(1) A kind of tungsten tailings autoclaved aerated concrete and its preparation method provided by the present invention, the present invention uses tungsten tailings to replace the quartz sand used in the traditional autoclaved aerated concrete production process, and the replacement amount can be dynamically adjusted according to the production demand Adjustment, the maximum replacement amount can reach 100%, which can digest and stockpile tungsten tailings in large quantities, effectively alleviate the problem of tungsten tailings stockpiling, and at the same time ensure that the product strength is qualified, giving tungsten tailings the possibility of secondary utilization as a resource. Although the SiO ₂ content of the tungsten tailings in this application is low, the Al ₂ O ₃ content is about 10% higher than that of ordinary quartz sand. During the reaction process, the aluminum atoms will form aluminum-substituted tobermullite crystals by replacing the silicon atoms in the silicon-oxygen tetrahedral structure ( ^Q3 structure). 002 crystal form diffraction peak, sample B is the diffraction peak of tobermullite with Al ₂ O ₃ added, it can be observed that compared with the upper and lower peaks, there is a significant left shift, which is due to the substitution of aluminum atoms, silicon and oxygen tetrahedral The crystal form of the body (Q ³ structure) has become larger, which proves that in the case of high aluminum content, in addition to generating tobermullite, a kind of aluminum-derived tobermullite will also be generated, which can further improve the quality of the product. Strength of. It greatly reduces the production cost of steam pressurized concrete, and can save a lot of natural resources, and at the same time, it can digest a lot of tailings, reduce the environmental load, turn waste into treasure, and realize the sustainable development of industry and social economy.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained according to the structures shown in these drawings without creative effort.

Fig. 1 is the XRD detection figure of the product of the embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. The realization of the purpose of the present invention, functional characteristics and advantages will be further described in conjunction with the embodiments and with reference to the accompanying drawings. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

Apparently, the described embodiments are only some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other implementations obtained by persons of ordinary skill in the art without making creative efforts fall within the protection scope of the present invention.

The invention provides a tungsten tailings autoclaved aerated concrete, which comprises the following components in mass percentage:

50-75% sand material, 5-25% quicklime, 10-30% cementitious material, 0.1-2% water reducing agent, 1-5% dihydrate gypsum, 1.1-5% additive, 0.1-2% dodecahydrate Potassium aluminum sulfate and 0.1-1% aluminum powder paste, the additive is any one or both of sodium lauryl sulfate and water glass;

The sand material includes tungsten tailings and quartz sand, the mass percentage of the tungsten tailings in the sand material is 50-100%, the _SiO2 mass fraction of the tungsten tailings is less than ₅₀ %, and the _Al2O3 mass fraction is less than 13%.

The average particle size of the tungsten tailings used in the present invention is 25 μm after ball milling, which is similar to the particle size of finely ground quartz sand, and the particles can be uniformly dispersed in the slurry. Smaller particle size particles have a larger specific surface area, which can improve the hydration reaction process between materials during the autoclaving process and greatly increase the crystallinity. At the microscopic level, ball milling can distort the crystal lattice of particles, and even cut off the Si-O bond and Al-O bond on the surface, thereby generating highly active atomic groups, increasing the instability of the structure, and increasing its reactivity. , Increase the speed of hydration reaction, so as to improve the strength of autoclaved and concrete products.

The water glass used in the present invention can stabilize the slurry, not only can fill the air-generating pores and capillary pores, but also improve the overall pore structure of the autoclaved aerated concrete, and the silicon in the water glass can be further combined with the slurry during the autoclaving process. The Ca(OH) ₂ in the reaction reacts to form a high Si/Ca hydration product, which further improves the strength of the product.

Although the SiO ₂ content of the tungsten tailings used in the present invention is low, the Al ₂ O ₃ content is about 10% higher than that of ordinary quartz sand. The XRD results show that, in the case of low silicon content and high aluminum content, in addition to the formation of tobermorite (Tobermorite) during the steaming process, a kind of aluminum generation tobermorite will be generated to further improve the quality of the product. Strength of.

The dihydrate gypsum used in the invention can participate in the hydration reaction of cement and adjust the setting time of cement. At the same time, it can inhibit the digestion reaction speed of lime, improve the stability of slurry pouring, and significantly improve the shrinkage of products in the later stage.

The potassium aluminum sulfate dodecahydrate used in the present invention can release part of the carbon dioxide gas in an alkaline environment to achieve an auxiliary gas-generating effect. At the same time, it can release AL ³⁺ metal ions in the water phase to generate AL(OH) ₃ colloids, improve the early coupling of the product embryo, and achieve the effect of stabilizing the volume change.

The sodium lauryl sulfate used in the present invention can partially replace aluminum powder in autoclaved aerated concrete as an auxiliary means of gas generation. It is easily soluble in water, has good dispersibility, and can significantly improve the concentration of gas in the slurry. of dispersion. Because the surface is negatively charged, it has an emulsifying effect so that the bubbles are not easy to annihilate and break apart, so as to stabilize the structure of the bubbles and improve the strength of the embryo body.

As an optional embodiment, the digestion rate of the quicklime is >10 min, the digestion temperature is >50° C., and the calcium oxide content is >60%.

As an optional embodiment, the cementitious material includes any one or both of Portland cement and sulphoaluminate cement.

As an optional embodiment, the water reducer is any one or both of naphthalene-based water reducer and polycarboxylate water reducer.

As an optional embodiment, the content of SiO ₂ in the quartz sand is >70%, and the particle size of SiO ₂ is 15 μm-75 μm.

As an optional embodiment, the dihydrate gypsum is any one or more of natural gypsum, desulfurized gypsum and phosphogypsum.

As an optional embodiment, the water glass is a sodium silicate solution, the modulus of the sodium silicate solution is >1, and the mass fraction of the sodium silicate solution is >20%.

As an optional embodiment, the active ingredient content in the potassium aluminum sulfate dodecahydrate is >90%, and the pH value is 2.5-6.5.

As an optional embodiment, the active matter content of the sodium lauryl sulfate is greater than 30%, the petroleum ether soluble matter is greater than 1%, and the inorganic salt content is less than 10%.

The preparation method of a kind of tungsten tailings autoclaved aerated concrete provided by the invention comprises the following preparation steps:

S1 Dehydrate and dry the tungsten tailings, grind them finely by ball milling process, and sieve them, and take the part with a particle size of <0.075mm;

S2 adds quicklime, cementitious material, dihydrate gypsum, quartz sand, water in turn, and stirs to make a slurry, and then continues to add aluminum powder paste, sodium lauryl sulfate and potassium aluminum sulfate dodecahydrate to the slurry, so that The ratio of water to material in the slurry is 0.3-0.7, adding water glass and water reducer according to the expansion of the slurry, and then injecting into the mold for pre-curing, followed by cutting, autoclaving and drying to make a finished product.

The invention provides the implementation steps of using tungsten tailings to prepare autoclaved aerated concrete: first, dehydrate and dry the tungsten tailings with a _SiO2 mass fraction less than 50% and _{an Al2O3} mass fraction less than 13%, and grind them by ball milling Fine, sieve, and weigh the part with a particle size of less than 0.075 mm; then use tungsten tailings to replace quartz sand in the autoclaved aerated concrete batching, the replacement rate is 0%-100% (mass fraction), and then add Cementitious material, dihydrate gypsum, quicklime, water, after high-speed stirring, add aluminum powder, stir again evenly, pour into the mold, and then move into the rest room for pre-curing at a temperature higher than 40°C.

During the pre-curing process, the added aluminum powder will undergo a chemical reaction to generate hydrogen under alkaline heating conditions, and the poured slurry will start to foam and gradually rise and expand. With the progress of the hydration reaction of the cementitious material, the slurry will The material begins to harden and maintains its embryonic state after gasification. After forming, the embryo body is removed and cut according to the requirements, and then moved into the autoclave for autoclave curing and forming.

Example 1

1.1 Raw material ratio

The weight percentage specific data of each component of described embodiment 1 is shown in the table below.

1.2 Preparation steps

The tungsten tailings, quartz sand, quicklime, Portland cement, dihydrate gypsum, and sodium lauryl sulfate dried after ball milling are weighed according to the mass ratio, and the total mass is 40kg. Fully mix after weighing, pour into the mixer, add water, the water-material ratio is 0.61, and stir at a high speed of 350r/min for 5 minutes. Then add water reducing agent, then add aluminum powder paste; then pour into the mold after stirring at high speed for 1 minute, and control the pouring temperature to about 35°C. Then move it into the pre-curing room, set the ambient temperature to 70°C, and move it into the autoclave after standing still for 8 hours. The autoclave conditions are 50°C to 65°C for 30 minutes, then heating to 200°C, holding for 5 hours, then cooling naturally, removing the mold from the kettle to complete the sample preparation. Take autoclaved aerated concrete and form three 100mm×100mm×100mm cube specimens for each group, and test its compressive strength. The compressive strength of the reference specimen without water reducing agent was 2.1MPa after drying out of the kettle; the compressive strength of the sample with tungsten tailings instead of quartz sand after using water reducing agent and sodium lauryl sulfate was 3.6MPa, compared with The compressive strength of the benchmark specimen was increased by 71.4%.

Example 2

2.1 Raw material ratio

The weight percentage specific data of each component of described embodiment 2 is shown in the table below.

2.2 Preparation steps

The tungsten tailings, quartz sand, quicklime, Portland cement, dihydrate gypsum, and aluminum potassium sulfate dodecahydrate dried after ball milling were weighed according to the mass ratio, and the total mass was 40kg. Mix well after weighing, pour into the mixer, add water, the ratio of water to material is 0.63, stir at high speed for 5 minutes. Then add water reducing agent, then add water glass, and finally add aluminum powder paste; then stir at high speed for 1 minute and pour into the mold, and control the pouring temperature to about 35°C. Then move it into the pre-curing room, set the ambient temperature to 70°C, and move it into the autoclave after standing still for 8 hours. The autoclave conditions are heating to 180°C, holding the temperature for 5 hours, then cooling naturally, and removing the mold from the kettle to complete the sample preparation. Take autoclaved aerated concrete and form three 100mm×100mm×100mm cube specimens for each group, and test its compressive strength. The compressive strength of the benchmark specimen without adding water reducing agent and water glass was 1.9MPa after drying; the compressive strength of the sample using water reducing agent and water glass instead of tungsten tailings instead of quartz sand was 3.4MPa. The compressive strength of the specimen was increased by 78.9%.

Example 3

3.1 Raw material ratio

The weight percentage specific data of each component of described embodiment 3 is shown in the table below.

3.2 Preparation steps

Concrete preparation steps are with embodiment 1,

The compressive strength of the benchmark specimen without adding water reducing agent and water glass after drying out of the kettle was 1.9MPa; the sample using water reducing agent and water glass instead of tungsten tailings instead of quartz sand had a compressive strength of 3.8MPa when it was out of the kettle, which was higher than that of the benchmark The compressive strength of the test piece was increased by 100%.

Example 4

4.1 Raw material ratio

The weight percentage specific data of each component of described embodiment 4 is shown in the table below.

4.2 Preparation steps

Concrete preparation steps are with embodiment 1,

The compressive strength of the benchmark specimen without adding water reducing agent and water glass after drying out of the kettle was 1.9MPa; the sample using water reducing agent and water glass instead of tungsten tailings instead of quartz sand had a compressive strength of 3.2MPa when it was out of the kettle. The compressive strength of the specimen increased by 68.42%.

Example 5

5.1 Raw material ratio

The weight percentage specific data of each component of described embodiment 5 is shown in the table below.

5.2 Preparation steps

Concrete preparation steps are with embodiment 1,

The compressive strength of the standard test piece without adding water reducing agent and water glass after drying out of the kettle is 1.9MPa; the sample with water reducing agent and water glass instead of tungsten tailings instead of quartz sand is 3.6MPa, which is higher than the benchmark The compressive strength of the test piece was increased by 100%.

The above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Anyone skilled in the art can easily think of changes or substitutions within the technical scope disclosed in the present invention. Should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (7)

1. The tungsten tailing autoclaved aerated concrete is characterized by comprising the following components in percentage by mass: 50-75% of sand material, 5-25% of quicklime, 10-30% of cementing material, 0.1-2% of water reducing agent, 1-5% of dihydrate gypsum, 1.1-5% of additive, 0.1-2% of aluminum potassium sulfate dodecahydrate and 0.1-1% of aluminum powder paste, wherein the additive is any one or two of sodium dodecyl sulfate and water glass;

the sandThe material comprises tungsten tailings and quartz sand, wherein the mass percent of the tungsten tailings in the sand material is 50-100%, and the tungsten tailings are SiO ₂ Less than 50% by mass, al ₂ O ₃ The mass fraction is less than 13 percent; the average particle size of the tungsten tailings after ball milling is 25 mu m; the dihydrate gypsum is any one or more of natural gypsum, desulfurized gypsum and phosphogypsum; the water glass is a sodium silicate solution, the modulus of the sodium silicate solution is more than 1, and the mass fraction of the sodium silicate solution is more than 20%; the content of active ingredients in the aluminum potassium sulfate dodecahydrate is more than 90 percent, and the pH value is 2.5 to 6.5.

2. The tungsten tailing autoclaved aerated concrete according to claim 1, which is characterized in that: the slaking speed of the quicklime is more than 10min, the slaking temperature is more than 50 ℃, and the content of calcium oxide is more than 60%.

3. The tungsten tailing autoclaved aerated concrete according to claim 1, which is characterized in that: the cementing material comprises any one or two of Portland cement and sulphoaluminate cement.

4. The tungsten tailing autoclaved aerated concrete according to claim 1, which is characterized in that: the water reducing agent is one or two of a naphthalene water reducing agent and a polycarboxylic acid water reducing agent.

5. The tungsten tailing autoclaved aerated concrete according to claim 1, which is characterized in that: siO in the quartz sand ₂ Content > 70%, siO ₂ The particle size is 15-75 μm.

6. The tungsten tailing autoclaved aerated concrete according to claim 1, which is characterized in that: the content of active substances of the sodium dodecyl sulfate is more than 30 percent, the content of petroleum ether soluble substances is more than 1 percent, and the content of inorganic salts is less than 10 percent.

7. The preparation method of the tungsten tailing autoclaved aerated concrete according to claim 1, which is characterized by comprising the following preparation steps:

s1, dehydrating and drying tungsten tailings, grinding the tungsten tailings by a ball milling process, and sieving the tungsten tailings to obtain a part with a particle size of less than 0.075 mm;

s2, sequentially adding quicklime, a cementing material, dihydrate gypsum, quartz sand and water, stirring to prepare slurry, then continuously adding aluminum powder paste, sodium dodecyl sulfate and aluminum potassium sulfate dodecahydrate into the slurry, wherein the water-material ratio in the slurry is 0.3-0.7, adding water glass and a water reducing agent according to the expansion degree of the slurry, then injecting into a die, performing pre-curing, and then performing cutting, autoclaved curing and drying processes to prepare a finished product.

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