阅读说明：本技术 一种气硬性无机胶凝材料及其制备方法 (Air-hardening inorganic cementing material and preparation method thereof ) 是由 罗利明 彭同江 孙红娟 唐颂 于 2021-09-22 设计创作，主要内容包括：本发明提供了一种气硬性无机胶凝材料及其制备方法,所述制备方法包括：将含有蛇纹石矿物的原料进行干燥、破碎和粉磨处理,获得第一粉体；将含有碳酸盐的矿物进行干燥、破碎和粉磨处理,获得第二粉体；按预定质量比混合第一粉体和第二粉体,并加热煅烧,获得以活性硅酸镁为主要成分的第三粉体；将第三粉体粉磨处理后,获得气硬性无机胶凝材料。气硬性无机胶凝材料采用上述制备方法制备获得。本发明获得的气硬性无机胶凝材料硬化后具有孔隙率低、抗压强度大、耐水性强、防火性能好、耐温性能好等优点,在建筑材料工业中具有重要的用途。(The invention provides an air-hardening inorganic cementing material and a preparation method thereof, wherein the preparation method comprises the following steps: drying, crushing and grinding a raw material containing serpentine minerals to obtain first powder; drying, crushing and grinding the mineral containing carbonate to obtain second powder; mixing the first powder and the second powder according to a preset mass ratio, and heating and calcining to obtain third powder with active magnesium silicate as a main component; and grinding the third powder to obtain the air-setting inorganic cementing material. The air-setting inorganic gelled material is prepared by the preparation method. The air hardening inorganic cementing material obtained by the invention has the advantages of low porosity, high compressive strength, high water resistance, good fireproof performance, good temperature resistance and the like after being hardened, and has important application in the building material industry.)

1. A preparation method of an air-hardening inorganic cementing material is characterized by comprising the following steps:

drying, crushing and grinding a raw material containing serpentine minerals to obtain first powder;

drying, crushing and grinding the mineral containing carbonate to obtain second powder;

mixing the first powder and the second powder according to a preset mass ratio, and heating and calcining to obtain third powder with active magnesium silicate as a main component;

and grinding the third powder to obtain the air-setting inorganic cementing material.

2. The method for producing an air-hardenable inorganic cementitious material according to claim 1, characterized in that the serpentine mineral-containing raw material includes at least one of serpentine, serpentine mill tailings, serpentine gangue, chrysotile mill tailings, and ultrabasic rock type metal mineral mill tailings.

3. The method of preparing an air hardenable inorganic cementitious material according to claim 1, wherein the carbonate containing minerals comprise at least one of marble, marble solid waste, limestone solid waste, dolomite solid waste, magnesite, and magnesite solid waste.

4. The preparation method of the air-setting inorganic cementitious material of claim 1, wherein the predetermined mass ratio of the first powder to the second powder is (40-60): (40-60).

5. The method for preparing the air-hardenable inorganic cementing material according to claim 1, wherein the calcination temperature is 700 ℃ to 1100 ℃ and the calcination time is 5min to 1.5 h.

6. The method for preparing an air-hardenable inorganic cementitious material according to claim 1, wherein the drying, crushing and grinding are performed under a negative pressure environment having a pressure of 5 to 10Pa lower than the external atmospheric pressure.

7. The method for preparing the air-hardenable inorganic cement of claim 1, wherein the particle size of the first powder is 150 μm or less, the particle size of the second powder is 150 μm or less, and the particle size of the air-hardenable inorganic cement is 75 μm or less.

8. The method for preparing air-setting inorganic cementitious material of claim 1, wherein the first powder comprises 25-40% MgO and 35-40% SiO by mass₂、2％～10％CaO、5％～15％Fe₂O₃、1％～5％Al₂O₃And 8-15% of H₂O⁺The second powder comprises 15-25% of MgO and 20-40% of SiO₂、15％～30％CaO、3％～12％Fe₂O₃、1％～5％Al₂O₃And 8% -15% of H₂O⁺。

9. An air-setting inorganic cementing material, characterized in that the air-setting inorganic cementing material is prepared by the method for preparing the air-setting inorganic cementing material according to any one of the claims 1 to 8, and the air-setting inorganic cementing material comprises 25 to 40 percent of MgO and 35 to 40 percent of SiO by mass percentage₂、2％～20％CaO、2～15％Fe₂O₃And 2-8% of Al₂O₃。

10. The air hardenable inorganic cement according to claim 9, wherein the air hardenable inorganic cement has a porosity of 10 to 30% and a specific surface area of 15m²/g～35m²/g。

Technical Field

The invention relates to the technical field of inorganic cementing materials, in particular to an air-setting inorganic cementing material and a preparation method thereof.

Background

At present, inorganic cementing materials applied in China, such as cement, lime, gypsum and the like, have good gelling property under certain conditions as main active components of calcareous cementing materials which are used as magnesium in the same family with calcium and partial magnesian materials, such as magnesium silicate, magnesium oxide and the like, and can be used for preparing the magnesian cementing materials.

Whether cement or lime, has been producedIn the process, a large amount of CO is generated₂Today, with the increasing severity of greenhouse effect, how to reduce carbon emission and realize carbon neutralization has become a significant problem to be considered at a national level.

In addition, a large amount of domestic serpentine-containing solid wastes can only be stockpiled for treatment due to lack of an effective resource approach, so that the valuable land resources are occupied, the surrounding environment is also polluted potentially, and meanwhile, the serpentine-containing solid wastes can be converted into an active gelled material without adverse effects on the environment by certain treatment means, so that the potential safety hazards of the environment are eliminated, the wastes are changed into valuables, the idle and waste of resources can be avoided, the calcium gelled material is replaced by the serpentine-containing solid wastes, the carbon emission of the calcium gelled material can be effectively reduced, and the serpentine-containing solid wastes have important economic, ecological, environmental-friendly and social benefits.

The latest research shows that the magnesian cementing material has the advantages of good compressive strength, low pH value (compared with the traditional portland cement) and the like, has the characteristic that the hydration product can form enstatite and olivine after being calcined, and has wide application and development prospects in the fields of building materials and refractory materials. However, the market price of the raw materials of the magnesium cementing material is high, and the production of the raw materials also needs a large amount of energy consumption, so that the method does not accord with the concept of environmental protection.

Disclosure of Invention

The present invention aims to address at least one of the above-mentioned deficiencies of the prior art. For example, one of the objects of the present invention is to provide a method for preparing an air-setting inorganic cementitious material using activated magnesium silicate as a main component from serpentine-containing solid waste.

In order to achieve the above object, an aspect of the present invention provides a method for preparing an air-hardenable inorganic cement, the method comprising the steps of:

drying, crushing and grinding a raw material containing serpentine minerals to obtain first powder;

drying, crushing and grinding the mineral containing carbonate to obtain second powder;

mixing the first powder and the second powder according to a preset mass ratio, and heating and calcining to obtain third powder with active magnesium silicate as a main component;

and grinding the third powder to obtain the air-setting inorganic cementing material.

In one exemplary embodiment of the method for preparing an air-hardenable inorganic cementitious material of the present invention, the serpentine mineral-containing raw material may include at least one of serpentine, serpentine mill tailings, serpentine gangue, chrysotile mill tailings, ultrabasic rock type metal mineral mill tailings.

In one exemplary embodiment of the method for preparing an air-hardenable inorganic cementitious material of the present invention, the carbonate-containing minerals may include at least one of marble, marble solid waste, limestone solid waste, dolomite solid waste, magnesite, and magnesite solid waste.

In an exemplary embodiment of the method for preparing an air-hardenable inorganic cement of the present invention, the predetermined mass ratio of the first powder to the second powder may be (40-60): (40-60).

In one exemplary embodiment of the method for preparing the air-hardenable inorganic cement of the present invention, the calcination temperature may be 700 ℃ to 1100 ℃ and the calcination time may be 5min to 1.5 h.

In an exemplary embodiment of the method for preparing an air-hardenable inorganic cement of the present invention, the drying, crushing, and pulverizing processes may be performed under a negative pressure environment having a pressure of 5 to 10Pa lower than the external atmospheric pressure.

In an exemplary embodiment of the method for preparing an air-hardenable inorganic cement of the present invention, the particle size of the first powder may be 150 μm or less, the particle size of the second powder may be 150 μm or less, and the particle size of the air-hardenable inorganic cement may be 75 μm or less.

In an exemplary embodiment of the method for preparing an air-hardenable inorganic cement of the present invention, the first powder may include 25% to 40% MgO, 35% to 40% SiO, by mass₂、2％～10％CaO、5％～15％Fe₂O₃、1％～5％Al₂O₃And 8-15% of H₂O +, the second powder can comprise 15% -25% of MgO and 20% -40% of SiO₂、15％～30％CaO、3％～12％Fe₂O₃、1％～5％Al₂O₃And 8% -15% of H₂O+。

According to another aspect of the present invention, an air-setting inorganic cementing material is provided, which is prepared by the above preparation method of the air-setting inorganic cementing material, and comprises, by mass, 25% -40% of MgO and 35% -40% of SiO₂、2％～20％CaO、2～15％Fe₂O₃And 2-8% of Al₂O₃。

In an exemplary embodiment of the air hardenable inorganic cement of the present invention, the air hardenable inorganic cement may have a porosity of 10% to 30% and a specific surface area of 15m²/g～35m²/g。

Compared with the prior art, the beneficial effects of the invention comprise at least one of the following:

(1) according to the invention, the air-setting inorganic cementing material taking the active magnesium silicate as a main component is obtained by heating and calcining the dangerous solid waste containing the serpentine mineral, so that the carbon emission and the environmental pollution are reduced, the resource utilization of the solid waste containing the serpentine mineral is realized, the environment is protected, the land resource is saved, the waste is changed into the valuable, a new thought is provided for the non-toxic and harmless treatment of the dangerous waste, and the important ecological, environmental, economic and social benefits are achieved;

(2) the air-setting inorganic gelled material taking the active magnesium silicate as the main component expands the source and the range of the gelled material, is beneficial to promoting the construction of domestic infrastructure, effectively relieves the contradiction that building materials are increasingly tense in the urbanization process, simultaneously favorably promotes the application of the magnesium gelled material, and actively responds to the solid waste material recycling policy vigorously advocated and popularized by the nation;

(3) the air-hardening inorganic cementing material obtained by the invention has the advantages of low porosity (for example, the porosity is 10-30%), high compressive strength (for example, the compressive strength of a 28d hardened body can reach 25-65 MPa), high water resistance, good fireproof performance, good temperature resistance and the like after being hardened, and has important application in the building material industry.

Detailed Description

Hereinafter, the air-setting inorganic cementitious material and the method of preparing the same of the present invention will be described in detail with reference to the exemplary embodiments.

It should be noted that "first," "second," and the like are merely for convenience of description and for ease of distinction, and are not to be construed as indicating or implying relative importance. For those of ordinary skill in the art, the term "pressure" in part herein corresponds to pressure.

At present, domestic construction is in vogue, a large amount of inorganic cementing materials are needed, domestic mainstream inorganic cementing materials are mainly calcium cementing materials, the product type is single, magnesium cementing materials represented by magnesium silicate have excellent service performance, but the manufacturing raw materials are expensive. Meanwhile, the accumulation of a large amount of domestic serpentine mineral-containing solid wastes brings serious influence and harm to the environment, and the serpentine mineral is an important raw material of the magnesium silicate cementing material, so that a large amount of land resources are occupied while the accumulation of the serpentine mineral is carried out, and idle waste of resources is also caused.

Aiming at the characteristics, the invention provides the air-hardening inorganic cementing material which is prepared by taking serpentine-containing solid waste as a raw material and takes active magnesium silicate as a main component. The method not only can change waste into valuable, consume a large amount of solid waste containing serpentine, save land resources, reduce the influence and harm to the environment, but also can widen the range of the cementing material, reduce the dependence on cement cementing materials, save energy, reduce emission, reduce the excavation and exploitation of limestone and clay, thereby protecting ecology and environment and having wide market prospect, social benefit and economic benefit.

In order to achieve the above objects, one aspect of the present invention provides a method for preparing an air-setting inorganic cementitious material.

In one exemplary embodiment of the method for preparing an air hardenable inorganic cement of the present invention, a method for preparing an air hardenable inorganic cement may include the steps of:

(1) drying, crushing and grinding the raw material containing the serpentine mineral to obtain first powder.

The raw material containing serpentine mineral can comprise at least one of serpentine, serpentine tailings, serpentine waste rock, chrysotile tailings and super-bedrock metal mineral tailings.

The main mineral composition of the first powder is serpentine, and the first powder contains a small amount of talc, magnetite, chlorite, magnesite, olivine, pyroxene and the like.

Further, the first powder can comprise 25-40% of MgO and 35-40% of SiO by mass percentage₂、2％～10％CaO、5％～15％Fe₂O₃、1％～5％Al₂O₃And 8-15% of H₂O⁺。

Further, the particle size of the first powder may be 45 μm to 150 μm. If the particle size of the first powder is too fine (for example, the particle size is below 25 μm), although the performance of the later-stage product (namely, the air-hardening inorganic cementing material) is improved, the processing cost is too high, and the cost performance is low; if the particle size of the first powder is too coarse (for example, the particle size is below 250 μm), the activity of the prepared composite gel material is low, which is not beneficial for practical application. Therefore, the granularity of the first powder is set to be 45-150 mu m, which is an optimal range, and the first powder has better cost performance in the range. For example, the first powder may have a particle size of 45 μm, 55 μm, 75 μm, 85 μm, 105 μm, 125 μm, 150 μm, or the like.

In addition, the drying, crushing and grinding treatment is completed in a negative pressure environment with the pressure 5-10 Pa lower than the external atmospheric pressure. The negative pressure can let the fresh air of workshop outside flow in, and the dust that contains asbestos fibre in the workshop discharges fixed place through special dust extraction, can not discharge outside the workshop to reduce environmental pollution. If the negative pressure is more than 10Pa, the negative pressure environment can affect the health of staff, and meanwhile, the air flowing speed in a workshop is increased, so that dust is easy to fly, and indoor air cannot be supplemented in time, so that the negative pressure environment is in a slight vacuum state. If the negative pressure is less than 5Pa, the negative pressure effect is poor.

(2) And drying, crushing and grinding the mineral containing the carbonate to obtain second powder.

The carbonate-containing minerals may include at least one of marble, marble solid waste, limestone solid waste, dolomite solid waste, magnesite, and magnesite solid waste. It should be noted that the solid waste refers to solid waste, including tailings, mining stripping waste rock, rock processing leftover, and the like.

The carbonate-containing minerals mainly comprise calcite, dolomite, aragonite, limestone, siderite, magnesite, iron dolomite, clay and the like.

The particle size of the second powder formed after crushing the carbonate-containing mineral may be 45 μm to 150 μm. If the particle size of the second powder is too fine (for example, the particle size is below 25 μm), although the performance of the later-stage product (namely, the air-hardening inorganic cementing material) is improved, the processing cost is too high, and the cost performance is low; if the particle size of the second powder is too coarse (for example, the particle size is below 250 μm), the activity of the prepared air-hardening binding material is low, which is not favorable for practical application. Therefore, the granularity of the second powder is set to be 45-150 mu m, which is an optimal range, and the second powder has better cost performance in the range. For example, the particle size of the second powder can be 45 μm, 55 μm, 75 μm, 85 μm, 105 μm, 125 μm, 150 μm, and the like.

Further, the second powder may include 15 to 25 mass% of MgO and 20 to 40 mass% of SiO₂、15％～30％CaO、3％～12％Fe₂O₃、1％～5％Al₂O₃And 8% -15% of H₂O⁺。

(3) And mixing the first powder and the second powder according to a preset mass ratio, uniformly mixing, putting into a calcining furnace, heating, calcining and activating to obtain third powder taking the active magnesium silicate as a main component.

Wherein the predetermined mass ratio of the first powder to the second powder can be (40-60): (40-60), namely 2: 3-3: 2. for example, the predetermined mass ratio of the first powder and the second powder may be 2: 3. 1: 1. 3: 2, etc. Setting the predetermined mass ratio of the first powder to the second powder to (40-60): (40-60), can rationally utilize asbestos tailing resources. If the predetermined mass ratio of the first powder to the second powder is lower than (40-60): (40-60) (for example, the predetermined mass ratio is 20: 80), the utilization rate of tailings or tailings resources containing serpentine minerals is low, and large-scale comprehensive utilization of the tailings or tailings resources cannot be realized; and when the predetermined mass ratio of the first powder to the second powder is higher than (40-60): (40-60) (for example, the predetermined mass ratio is 90: 10), the performance of the prepared air-hardening inorganic cementing material can not be ensured to meet the application requirements.

Calciners include, but are not limited to, shaft kilns, rotary kilns, precalciners, suspension kilns, and the like. The calcining temperature can be 700-1100 ℃, and the calcining time can be 5 min-1.5 h. For example, the calcination temperature may be 700 ℃, 800 ℃, 900 ℃, 1000 ℃, 1100 ℃ or the like, and the calcination time may be 5min, 15min, 35min, 45min, 60min, 75min, 90min or the like.

The main purpose of calcination is to convert the powder mainly containing serpentine mineral raw material into an amorphous product with active magnesium silicate powder mainly containing magnesium oxide and silicon oxide, so as to improve the reactivity of the powder and contain a small amount of olivine crystal phase. If the calcination temperature is too low (e.g., below 700 ℃), the conversion rate of the amorphous product is low and the purpose of calcination cannot be achieved; if the calcination temperature is too high (e.g., above 1100 ℃), it is mainly converted into a crystalline phase, which significantly reduces the activity of the cement. The same applies to the calcination time, and too short or too long time can reduce the gelling property of the powder. Therefore, 700 ℃ to 1100 ℃ is the optimal calcining temperature range, and 5min to 1.5h is the optimal calcining time range.

(4) And grinding the third powder to obtain the air-setting inorganic cementing material with active magnesium silicate as the main component.

The air-hardening inorganic gelling material based on activated magnesium silicate finally obtained contains amorphous silicon dioxide, amorphous magnesium oxide and calcium oxide as main components, and further contains a small amount of olivine crystals.

Further, the particle size of the ground air-hardening inorganic cementing material can be 10-75 μm. If the particle size of the air-hardenable inorganic cement is too fine (e.g., less than 5 μm), the cement activity will be improved, but the raw material processing cost will be increased; if the particle size of the air-hardenable inorganic cement is too coarse (e.g., greater than 100 μm), the activity of the composite cement is significantly reduced. When the particle size is in the range of 10 μm to 75 μm, both processing cost and performance can be considered, so that there is an optimum particle size range.

In another aspect, the present invention provides an air-setting inorganic cementitious material.

In an exemplary embodiment of the air-hardenable inorganic cement of the present invention, an air-hardenable inorganic cement is prepared using the method for preparing an air-hardenable inorganic cement as described above.

The air hardening inorganic cementing material can comprise 25 to 40 percent of MgO and 35 to 40 percent of SiO by mass percent₂、2％～20％CaO、2～15％Fe₂O₃And 2-8% of Al₂O₃。

The air-setting inorganic cementing material has the gelatinization property after being uniformly mixed with water, the formed body is cured and solidified into a stone body in the air, the strength of the stone body is 5MPa to 65MPa, the initial setting volume stability is good, the stone body does not expand after absorbing water, frost return does not occur, and the durability is strong.

The air hardening inorganic gelled material has high porosity (10-30%) and large specific surface area (15 m)²/g～35m²The water-absorbing agent contains alkaline calcium oxide and magnesium oxide active components, and has strong water absorption and water retention. The workability of the mortar can be obviously improved by mixing cement mortar and preparing mixed mortar.

The gelling and curing mechanism of the air-setting inorganic cementing material of the invention is as follows:

the air hardening inorganic cementing material contains active silicon oxide SiO₂And active magnesium oxide (MgO) which forms a hydration product under the action of water and has gelling property.

Active SiO in air-hardening inorganic cementing material₂Can react with calcium oxide to form sheet or needle calcium silicate hydrate; active oxidationActive MgO and active silica SiO in magnesium₂The simultaneous reaction with CaO and magnesium sulfate may form basic magnesium sulfate and deepened calcium silicate, and the like.

Therefore, the air-setting inorganic gelling material can form a stone body after hydration.

The air-setting inorganic cementing material which is prepared by the invention and takes the active magnesium silicate as the main component has air-setting property after being evenly mixed with water, and the density of a formed and cured solidified body is 1.3g/cm³～2.2g/cm³The compressive strength can reach M5-M65.

Tests prove that the air-hardening inorganic cementing material has the following characteristics:

(1) the air hardening inorganic cementing material obtained by the invention has low porosity (for example, the porosity is 10-30%) after hardening, the internal porosity of the slurry after hardening is only about 50% of that of a gypsum hardened body, and the specific surface area is 15m²/g～35m²And/g, strong water absorption and retention. The workability of the mortar can be obviously improved by mixing cement mortar and preparing mixed mortar; the product has the characteristics of medium apparent density, medium strength, wide adaptability and the like; the structural performance of the product can be obviously improved by adding a proper amount of hydraulic materials such as cement, slag and the like.

(2) The air hardening inorganic cementing material of the invention is hardened by drying and hydration, after curing, the 28d hardened body has the strength and the compressive strength of 25 MPa-65 MPa, and the hardened body can not be dissolved and dispersed when meeting water. Therefore, the hardened body of the cement material can be used in an environment where it is wet and soaked in water for a long period of time. The magnesium silicate gel material does not contain soluble salt, and the hardened body does not turn white after being rained (water) or absorbed moisture.

(3) The air-hardening inorganic cementing material has less evaporated moisture in the hardening process, does not cause obvious volume shrinkage, and is not easy to generate dry shrinkage cracks. The volume change is small when the mortar is hardened, the mortar is not obviously shrunk like lime and cement when being solidified and hardened, and the surface of the hardened body is smooth and full. The hardened body has poor hygroscopicity and strong water resistance; the water can not be obviously reduced in strength after being soaked for a long time, and the frost resistance is strong.

(4) The air-setting inorganic cementing material can be used independently, and can also be doped with materials such as cement, sand, paper ribs, hemp knives, glass fibers and the like so as to increase the mechanical strength and save the magnesium silicate cementing material.

(5) The air-setting inorganic binder of the present invention has weak alkalinity, and can react with amorphous activated silica or activated magnesium oxide under steam curing conditions to form a hydraulic product, thereby producing a cement. The magnesium silicate cementing material product does not contain chloride ions and has no corrosion to steel. Therefore, magnesium silicate cementitious materials have important uses in the building materials industry.

(6) The air hardening inorganic cementing material of the invention has slower setting and hardening at normal temperature. The initial setting time and the final setting time of the slurry are both long, the initial setting time is generally 30-300 min, the final setting time is within 5-12 h, and the slurry is completely hardened after 28 d. To meet the construction requirements, accelerators such as sodium aluminate, magnesium sulfate, water glass, sodium (bi) carbonate, high alumina cement and sulphoaluminate cement can be added as required to improve the application performance.

(7) The air-setting inorganic cementing material has good fireproof performance. When a magnesium silicate gel material product encounters a fire, the magnesium silicate gel material product has high heat absorption amount, releases certain water vapor, reduces the ignition point temperature, forms a vapor curtain and a dehydrate heat insulation layer on the surface of the product, and can effectively reduce the harm of flame to an internal structure. The article itself is not severely damaged while it is being fire protected.

(8) The air hardening inorganic cementing material has good high temperature resistance. The hardened magnesium silicate gel material has good high-temperature resistance, and the strength of the hardened magnesium silicate gel material is still kept above 95% after the hardened magnesium silicate gel material is heated for 1-3 hours at the temperature of 200-950 ℃.

In order that the above-described exemplary embodiments of the invention may be better understood, further description thereof with reference to specific examples is provided below.

Example 1

A method for preparing air-hardening inorganic cementing material with active magnesium silicate as main component includes the following steps:

s1, drying and crushing the serpentine beneficiation tailings under the negative pressure condition that the pressure is 5Pa lower than the external atmospheric pressure to obtain first powder which mainly contains serpentine mineral raw materials and has the particle size of 120-150 mu m. Wherein, the main mineral composition of the first powder is serpentine, and simultaneously, the first powder contains a small amount of talc, magnetite, chlorite, magnesite, olivine and pyroxene.

The main chemical composition of the first powder is as follows by mass percent: 26% MgO and 40% SiO₂、10％CaO、14％Fe₂O₃、2％Al₂O₃And 8% of H₂O⁺。

S2, drying, crushing and grinding the calcite tailings to 120-150 mu m to obtain second powder.

The main chemical composition of the second powder can be as follows by mass percent: 15% MgO and 30% SiO₂、30％CaO、12％Fe₂O₃、5％Al₂O₃And 8% of H₂O⁺。

S3, mixing the first powder obtained in the step S1 and the second powder obtained in the step S2 according to the weight ratio of 3: 2, and putting the mixture into a calcining furnace for heating, calcining and activating after uniformly mixing, wherein the calcining temperature is 750 ℃, and the calcining time is 60min, so as to obtain third powder taking the active magnesium silicate as a main component.

S4, ball-milling the third powder with the active magnesium silicate as the main component obtained in the step S3 by a ball mill for 6 hours to obtain the air-setting inorganic cementing material with the particle size of 45 mu m, the passing rate of 75 mu m and the passing rate of 100 percent, wherein the air-setting inorganic cementing material with the active magnesium silicate as the main component.

Mixing the air-hardening inorganic cementing material which is finally obtained and takes the active magnesium silicate as the main component with standard sand and water, forming and curing for 28 days to obtain a cured body with the density of 1.5g/cm³The compressive strength was M25.

The air-setting inorganic gelled material hardened body can not be dissolved and dispersed when meeting water. Therefore, the air-setting inorganic cementitious material hardened body can be used in an environment where it is wet and soaked in water for a long period of time.

The air hardening cementing material has the gelatinization property after being mixed with water and cured in the air into a stone-like body, the strength of the stone-like body is 5MPa to 65MPa, the initial setting volume stability is good, the stone-like body does not expand after absorbing water, frost return does not occur, the durability is strong, and holes are formedHigh porosity (10-30%), large specific surface area (15 m)²/g～35m²The water-absorbing agent contains alkaline calcium oxide and magnesium oxide active components, and has strong water absorption and water retention. The workability of the mortar can be obviously improved by mixing cement mortar and preparing mixed mortar.

Example 2

A method for preparing air-hardening inorganic cementing material with active magnesium silicate as main component includes the following steps:

s1, drying and crushing the serpentine beneficiation tailings under the negative pressure condition that the pressure is 8Pa lower than the external atmospheric pressure to obtain first powder which mainly contains serpentine mineral raw materials and has the particle size of 45-80 microns. Wherein, the main mineral composition of the first powder is serpentine, and simultaneously, the first powder contains a small amount of talc, magnetite, chlorite, magnesite, olivine and pyroxene.

The main chemical composition of the first powder is as follows by mass percent: 40% MgO and 35% SiO₂、5％CaO、7％Fe₂O₃、3％Al₂O₃And 10% of H₂O⁺。

S2, drying, crushing and grinding the siderite tailings to 45-80 μm to obtain second powder.

The main chemical composition of the second powder can be as follows by mass percent: 20% MgO and 40% SiO₂、20％CaO、5％Fe₂O₃、1％Al₂O₃And 14% H₂O⁺。

S3, mixing the first powder obtained in the step S1 and the second powder obtained in the step S2 according to the weight ratio of 1: 1, and putting the mixture into a calcining furnace for heating, calcining and activating after uniformly mixing, wherein the calcining temperature is 1000 ℃, and the calcining time is 10min, so as to obtain third powder taking the active magnesium silicate as a main component.

S4, ball-milling the third powder which is obtained in the step S3 and takes the active magnesium silicate as the main component for 10 hours by adopting a ball mill to obtain the air-setting inorganic gelled material which has the grain diameter of 10-75 mu m and the 45 mu m sieve passing rate of more than or equal to 55 percent and takes the active magnesium silicate as the main component.

The finally obtained magnesium silicate with activity is used as the main componentThe air-hardening inorganic gelled material of the components is mixed with standard sand and water, and after molding and curing for 28 days, the density of the obtained cured body is 2.0g/cm³The compressive strength was M55.

Example 3

A method for preparing air-hardening inorganic cementing material with active magnesium silicate as main component includes the following steps:

s1, drying and crushing the serpentine beneficiation tailings under the negative pressure condition that the pressure is 10Pa lower than the external atmospheric pressure to obtain first powder which mainly contains serpentine mineral raw materials and has the particle size of 80-120 mu m. Wherein, the main mineral composition of the first powder is serpentine, and simultaneously, the first powder contains a small amount of talc, magnetite, chlorite, magnesite, olivine and pyroxene.

The main chemical composition of the first powder is as follows by mass percent: 30% MgO and 38% SiO₂、8％CaO、10％Fe₂O₃、5％Al₂O₃And 9% of H₂O⁺。

S2, drying, crushing and grinding the limestone tailings to 80-120 mu m to obtain second powder.

The main chemical composition of the second powder can be as follows by mass percent: 25% MgO and 20% SiO₂、25％CaO、10％Fe₂O₃、5％Al₂O₃And 15% of H₂O⁺。

S3, mixing the first powder obtained in the step S1 and the second powder obtained in the step S2 according to the weight ratio of 2: 3, and putting the mixture into a calcining furnace for heating, calcining and activating after uniformly mixing, wherein the calcining temperature is 850 ℃, and the calcining time is 30min, so as to obtain third powder taking the active magnesium silicate as a main component.

S4, ball-milling the third powder which is obtained in the step S3 and takes the active magnesium silicate as the main component for 10 hours by adopting a ball mill to obtain the air-setting inorganic gelled material which has the grain diameter of 10-75 mu m and the 45 mu m sieve passing rate of more than or equal to 65 percent and takes the active magnesium silicate as the main component.

Mixing the air-hardening inorganic cementing material which is finally obtained and takes the active magnesium silicate as the main component with standard sand and water, and after molding and curing for 28 days, obtaining the productCured body density 1.8g/cm³The compressive strength was M40.

In summary, the beneficial effects of the invention include at least one of the following:

(1) according to the invention, the air-hardening inorganic cementing material taking the active magnesium silicate as a main component is obtained by heating and calcining the dangerous solid waste containing the serpentine mineral, so that the method is beneficial to reducing carbon emission and environmental pollution, realizes resource utilization of the solid waste containing the serpentine mineral, is beneficial to protecting the environment, saving land resources and changing waste into valuable, provides a new thought for nontoxic and harmless treatment of the dangerous waste, and has important ecological, environmental, economic and social benefits.

(2) The air-hardening inorganic cementing material taking the active magnesium silicate as the main component expands the source and the range of the cementing material, is beneficial to promoting the construction of domestic infrastructure, effectively relieves the contradiction of increasingly tense building materials in the urbanization process, simultaneously favorably promotes the application of the magnesium cementing material, and actively responds to the solid waste material recycling policy vigorously advocated and popularized by the nation.

(3) The air-hardening inorganic cementing material obtained by the invention has the advantages of low porosity (for example, the porosity is 10-30%), high compressive strength (for example, the compressive strength of a 28d hardened body can reach 25-65 MPa), high water resistance, good fireproof performance, good temperature resistance and the like after being hardened, and has important application in the building material industry.

While the present invention has been described above in connection with exemplary embodiments, it will be apparent to those of ordinary skill in the art that various modifications may be made to the above-described embodiments without departing from the spirit and scope of the claims.