Magnesium oxychloride cement prepared from old brine of salt lake and preparation method of magnesium oxychloride cement

Abstract

The invention relates to the technical field of green building materials, in particular to magnesium oxychloride cement prepared from salt lake old brine and a preparation method of the magnesium oxychloride cement. The magnesium oxychloride cement is prepared from the following raw materials in parts by mass: 90-100.0 parts of the old brine of the salt lake, 85.9-112.8 parts of light calcined magnesia, 0-32.2 parts of steel slag micro powder, 83.8-90 parts of tap water and 1.4-2.2 parts of a composite water repellent agent. The preparation method provided by the invention is simple in process, low in raw material cost and suitable for industrial production. The magnesium oxychloride cement prepared by the preparation method disclosed by the invention is good in water resistance, and has important significance on comprehensive utilization of regional resources and industrial development of green building materials.

Description

Technical Field

[0001] This invention relates to the field of green building materials technology, and in particular to a magnesium oxychloride cement prepared using old brine from a salt lake and its preparation method. Background Technology

[0002] A certain salt lake produces 1.5 million tons of potassium sulfate annually, while the byproduct magnesium chloride produces approximately 4.5 million tons annually. However, as a primary product, magnesium chloride's annual sales volume is less than 100,000 tons. Magnesium chloride that cannot be recycled is discharged back into the salt lake as old brine. This large amount of unused magnesium chloride not only drives up the production cost of potassium sulfate fertilizer but also pollutes the environment, seriously threatening the lives and health of local residents, creating a "magnesium hazard." Therefore, its resource utilization is urgently needed.

[0003] Magnesium oxychloride cement possesses advantages such as early strength, high strength, rapid setting, wear resistance, and resistance to brine corrosion. Its main applications include decorative materials, ventilation ducts, refractory bricks, and packaging materials as a substitute for wood. Currently, the annual consumption of magnesium oxychloride cement in China exceeds 3 million tons. A certain salt lake region has abundant MgCl2, which can be used to produce magnesium oxychloride cement. However, traditional magnesium oxychloride cement suffers from poor water resistance and is prone to efflorescence, limiting its application range. Summary of the Invention

[0004] To address the shortcomings of the existing technologies, the present invention aims to provide a magnesium oxychloride cement prepared using old brine from salt lakes and its preparation method. The preparation method provided by the present invention is simple, uses low-cost raw materials, and is scalable for preparing magnesium oxychloride cement from old brine in salt lakes. The magnesium oxychloride cement prepared by the present invention has good water resistance and is of great significance for the comprehensive utilization of regional resources and the development of the green building materials industry.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A magnesium oxychloride cement prepared using old brine from a salt lake is made from the following raw materials in parts by weight: 90-100.0 parts old brine from a salt lake, 85.9-112.8 parts lightly calcined magnesium oxide, 0-32.2 parts steel slag powder, 83.8-90 parts tap water, and 1.4-2.2 parts composite water-resistant agent.

[0006] In a preferred embodiment of the present invention, the salt lake brine is a filtrate from potassium extraction waste from a salt lake, with a density of 1.331 g·cm³. -3 -1.336g·cm -3 Mg in old brine of salt lake 2+ The content is 96.0-107.4 g / L, Na + The content is 3.2g / L-3.6g / L, K +The content is 2.5g / L-2.9g / L, SO4 2- The content was 40.0 g / L-46.2 g / L, Cl - The content of [specific component] is 298.3g / L-298.0g / L, and the content of other components is 6.9g / L-7.3g / L.

[0007] In a preferred embodiment of the present invention, the preparation method of magnesium oxychloride cement prepared by using old brine from a salt lake is as follows: old brine from a salt lake, lightly calcined magnesium oxide, steel slag powder and composite water-resistant agent are dissolved in water, poured into a mold, cured and then demolded to obtain magnesium oxychloride cement.

[0008] In a preferred embodiment of the present invention, the method for preparing lightly calcined magnesium oxide includes the following steps: sieving quicklime, dissolving it to obtain a lime slurry; adding the lime slurry to salt lake brine, allowing it to stand, filtering, drying, and calcining to obtain lightly calcined magnesium oxide.

[0009] In a preferred embodiment of the present invention, the activity of the slaked lime is 75%, the particle size is 0.075 mm, and the mass fraction of slaked lime in the lime slurry is 40%.

[0010] In a preferred embodiment of the present invention, the standing time is 24 hours, the calcination temperature is 600°C, and the calcination time is 1 hour.

[0011] In a preferred embodiment of the present invention, the steel slag powder is produced by a steel company, is gray-black powder, has a particle size of 0.04mm-0.075mm, an activity of 80%-90%, and is added at a rate of 10.0wt%-30.0wt% of lightly calcined magnesia.

[0012] In a preferred embodiment of the present invention, the composite water-resistant agent is a combination of phosphate, sodium polyacrylate and corn starch with a mass ratio of 1.0-1.5:2.5-3.0:0.5-1.0, and the amount of the composite water-resistant agent added is 1.0wt%-2.5wt% of lightly calcined magnesium oxide.

[0013] Another object of the present invention is to provide a preparation method described in any of the above claims to obtain magnesium oxychloride cement prepared using old brine from a salt lake.

[0014] The present invention describes the application of magnesium oxychloride cement prepared using old brine from salt lakes in green building materials and thermal insulation materials.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. The product obtained by the formula and preparation method of magnesium oxychloride cement prepared by using old brine of salt lake provided by the present invention has the characteristics of early setting, high strength, good water resistance, durability, no energy consumption, and no pollution. The process method of preparing magnesium oxychloride cement by using old brine after potassium extraction from salt lake is simple, the raw material cost is low, and magnesium oxychloride cement can be prepared on a large scale.

[0016] 2. The magnesium oxychloride cement prepared by this invention can accelerate the construction progress, has low cost and can replace silicate cement of C42.5 and above. It can be used in green building materials and insulation materials, and can solve the local "magnesium hazard" and industrial solid waste steel slag. It provides a new way for the development and utilization of salt lake resources and promotes the local economic development. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the implementation process of the present invention. Detailed Implementation

[0018] The following detailed description, in conjunction with embodiments of the present invention and accompanying drawings, provides a clear and complete illustration of the technical solutions in these embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0019] It should be noted that all technical terms used in this invention are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of this invention can be purchased from the market or prepared by existing methods.

[0020] Example 1 A method for preparing magnesium oxychloride cement using aged brine from a salt lake includes the following steps: (1) Weigh 143.2g of lightly calcined magnesium oxide with an active content of 75.0%.

[0021] (2) Weigh 1.3g of the composite water-resistant agent and dissolve it in 83.8g of water, then mix it with 100g of old salt lake brine to obtain the liquid component.

[0022] (3) Add the lightly calcined magnesium oxide to the liquid component and stir to form a uniform slurry.

[0023] (4) Pour the slurry into the mold, cure it in the natural environment for 24 hours, and then remove the mold to obtain magnesium oxychloride cement.

[0024] Example 2 A method for preparing magnesium oxychloride cement using aged brine from a salt lake includes the following steps: (1) Weigh 128.8g of lightly calcined magnesium oxide with an active content of 75.0% and weigh 10.7g of steel slag powder with a particle size of 0.075mm, mix them together to obtain mixed powder.

[0025] (2) Weigh 1.6g of the composite water-resistant agent and dissolve it in 83.8g of water, then mix it with 100g of old salt lake brine to obtain the liquid component.

[0026] (3) Add the mixed powder to the liquid component and stir to form a uniform slurry.

[0027] (4) Pour the slurry into the mold, cure it in the natural environment for 24 hours, and then remove the mold to obtain magnesium oxychloride cement.

[0028] Example 3 A method for preparing magnesium oxychloride cement using aged brine from a salt lake includes the following steps: (1) Weigh 114.6g of lightly calcined magnesium oxide with an active content of 75.0% and weigh 21.5g of steel slag powder with a particle size of 0.075mm, mix them together to obtain mixed powder.

[0029] (2) Weigh 1.8g of the composite water-resistant agent and dissolve it in 83.8g of water, then mix it with 100g of old salt lake brine to obtain the liquid component.

[0030] (3) Add the mixed powder to the liquid component and stir to form a uniform slurry.

[0031] (4) Pour the slurry into the mold, cure it in the natural environment for 24 hours, and then remove the mold to obtain magnesium oxychloride cement.

[0032] Example 4 A method for preparing magnesium oxychloride cement using aged brine from a salt lake includes the following steps: (1) Weigh 100.2g of lightly calcined magnesium oxide with an active content of 75.0% and weigh 32.2g of steel slag powder with a particle size of 0.075mm, mix them together to obtain mixed powder.

[0033] (2) Weigh 2.0g of the composite water-resistant agent and dissolve it in 83.8g of water, then mix it with 100g of old salt lake brine to obtain the liquid component.

[0034] (3) Add the mixed powder to the liquid component and stir to form a uniform slurry.

[0035] (4) Pour the slurry into the mold, cure it in the natural environment for 24 hours, and then remove the mold to obtain magnesium oxychloride cement.

[0036] Example 5 A method for preparing magnesium oxychloride cement using aged brine from a salt lake includes the following steps: (1) Weigh 150.4g of lightly calcined magnesium oxide with an active content of 75.0% and weigh 12.5g of steel slag powder with a particle size of 0.075mm, mix them together to obtain mixed powder.

[0037] (2) Weigh 2.2g of the composite water-resistant agent and dissolve it in 83.8g of water, then mix it with 100g of old salt lake brine to obtain the liquid component.

[0038] (3) Add the mixed powder to the liquid component and stir to form a uniform slurry.

[0039] (4) Pour the slurry into the mold, cure it in the natural environment for 24 hours, and then remove the mold to obtain magnesium oxychloride cement.

[0040] Results Analysis The component proportions in the preparation methods of magnesium oxychloride cement prepared using old brine from salt lakes in Examples 1-5 are shown in Table 1. Steel slag powder was not included in Example 1, while it was included in Examples 2-5.

[0041] Table 1. Proportions of each component The mechanical properties of magnesium oxychloride cement prepared using old brine from salt lake in Example 1 are shown in Table 2. Its 28-day compressive strength is 52.6 MPa, which exceeds 42.5 MPa, and it can replace C42.5 silicate cement.

[0042] The mechanical properties of the magnesium oxychloride cement prepared using old brine from a salt lake in Example 2 are shown in Table 2. Its 28-day compressive strength is 55.9 MPa, exceeding 52.5 MPa, and it can replace C52.5 silicate cement. The mechanical properties of the magnesium oxychloride cement prepared using old brine from a salt lake in Example 3 are shown in Table 2. Its 28-day compressive strength is 59.0 MPa, exceeding 52.5 MPa, and it can replace C52.5 silicate cement.

[0043] The mechanical properties of magnesium oxychloride cement prepared using old brine from salt lake in Example 4 are shown in Table 2. Its 28-day compressive strength is 53.2 MPa, which exceeds 52.5 MPa, and it can replace C52.5 silicate cement.

[0044] The mechanical properties of magnesium oxychloride cement prepared using old brine from salt lake in Example 5 are shown in Table 2. Its 28-day compressive strength is 65.5 MPa, which exceeds 62.5 MPa, and it can replace C62.5 silicate cement.

[0045] Therefore, the magnesium oxychloride cement prepared by the present invention using old brine from salt lakes can replace silicate cement of grade C42.5 and above, and can be used in fields such as green building materials and thermal insulation materials. It can solve the problem of "magnesium hazard" and industrial solid waste steel slag in the local area, provide a new way for the development and utilization of salt lake resources, and promote the development of the local economy.

[0046] Table 2 Compressive strength and flexural strength It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described here to avoid redundancy. Although preferred embodiments of the invention have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this invention.

[0047] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A magnesium oxychloride cement prepared using aged brine from a salt lake, characterized in that, It is made from the following raw materials in parts by weight: 90-100.0 parts of old brine from salt lake, 85.9-112.8 parts of lightly calcined magnesium oxide, 0-32.2 parts of steel slag powder, 83.8-90 parts of tap water, and 1.4-2.2 parts of composite water-resistant agent.

2. The magnesium oxychloride cement prepared using old brine from a salt lake according to claim 1, characterized in that, Salt lake brine is the filtrate from potassium extraction waste, with a density of 1.331 g·cm³. -3 -1.336g·cm -3 Mg in old brine of salt lake 2+ The content is 96.0 g / L-107.4 g / L, Na + The content is 3.2-3.6 g / L, K + The content is 2.5-2.9 g / L, SO4 2- The content was 40.0-46.2 g / L, Cl - The content of [specific component] is 298.3-298.0 g / L, and the content of other components is 6.9-7.3 g / L.

3. The magnesium oxychloride cement prepared using old brine from a salt lake according to claim 1, characterized in that, The method for preparing magnesium oxychloride cement using old brine from a salt lake is as follows: old brine from a salt lake, lightly calcined magnesium oxide, steel slag powder, and a composite water-resistant agent are dissolved in water to obtain magnesium oxychloride cement.

4. The magnesium oxychloride cement prepared using old brine from a salt lake according to claim 3, wherein the particle size of the steel slag powder is 0.04mm-0.075mm, the activity is 80%-90%, and the amount of steel slag powder added is 10.0wt%-30.0wt% of lightly calcined magnesium oxide.

5. The method for preparing magnesium oxychloride cement using old brine from a salt lake according to claim 3, characterized in that, The composite water-resistant agent is a combination of phosphate, sodium polyacrylate and corn starch with a mass ratio of 1.0-1.5: 2.5-3.0: 0.5-1.

0. The amount of composite water-resistant agent added is 1.0wt%-2.5wt% of lightly calcined magnesium oxide.

6. A method according to any one of claims 1-5 yields magnesium oxychloride cement prepared using old brine from a salt lake.

7. The application of magnesium oxychloride cement prepared using old brine from salt lakes as described in claim 6 in green building materials and thermal insulation materials.

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