A preparation method of a geological polymer precursor for fluorite tailings base

Abstract

The present invention discloses a preparation method of a geological polymer precursor for fluorite tailings base, comprising the following steps: (1) grinding the fluorite tailings; (2) uniformly mixing the ground fluorite tailings with sodium hydroxide, sodium carbonate, and lime powder in a certain proportion, and calcining the mixture in a high-temperature furnace to obtain a fluorite tailings mixed powder; (3) grinding the fluorite tailings mixed powder after calcination and natural cooling to obtain the geological polymer precursor for fluorite tailings base; (4) testing the compressive strength of the geological polymer precursor for fluorite tailings base. The present invention has the advantages of simple and easily available raw materials, low calcination temperature, and less carbon emissions, providing a new idea for the resource utilization of fluorite tailings.

Description

Technical Field

[0001] The present invention belongs to the technical field of resource utilization of solid waste, and particularly relates to a method for preparing a geological polymer precursor from fluorite tailings Background Art

[0002] Fluorite tailings are one of the bulk industrial solid wastes with the largest output, the lowest comprehensive utilization rate in China. The cumulative stockpile has reached more than 10 billion tons, the annual output is 1.2 billion tons, accounting for more than 50% of the world's tailings output. Fluorite tailings are by-products of fluorite smelting. Various fluorine-containing compounds in them react and dissolve in nature, and the generated fluoride ions will cause serious damage to the surrounding ecology. If the fluorite tailings are not properly treated, the fluoride ions in the solid will enter the surrounding water bodies along with the water flow, causing fluorine pollution. At the same time, it is the main component of industrial solid pollutants. Its large accumulation not only occupies land and damages vegetation, but also the tailings pond is a hidden danger of triggering geological disasters

[0003] The main component of fluorite tailings is silica, and its mineral composition is mainly composed of quartz, containing a small amount of feldspar and mica. At present, the utilization of fluorite tailings in building materials is limited to being used as aggregates in autoclaved lime-sand bricks and aerated concrete, and its potential activity has not been applied. If the reaction activity of fluorite tailings can be improved through activation means and a geological polymer precursor is prepared from it, its application value will be significantly improved and its resource utilization will be promoted Summary of the Invention

[0004] In order to solve the deficiencies in the prior art, the present invention provides a method for preparing a geological polymer precursor from fluorite tailings with simple process, easy operation, energy conservation and environmental protection, and low cost

[0005] To solve the above technical problems, the present invention adopts the following technical scheme: A method for preparing a geological polymer precursor from fluorite tailings, comprising the following steps

[0006] (1) Grinding the fluorite tailings

[0007] (2) Mixing the ground fluorite tailings with sodium hydroxide, sodium carbonate and lime powder in a certain proportion and mixing evenly, and calcining in a high-temperature furnace to form a fluorite tailings mixed powder

[0008] (3) Grinding the calcined and naturally cooled fluorite tailings mixed powder to obtain a geological polymer precursor from fluorite tailings

[0009] (4) Testing the compressive strength of the geological polymer precursor from fluorite tailings

[0010] In step (1), the specific surface area of the fluorite tailings after grinding is below 100 m 2 / kg

[0011] In step (2), the ratio of fluorite tailings, sodium hydroxide, sodium carbonate, and lime powder is 50 - 80 wt% of fluorite tailings, 10 - 50 wt% of sodium hydroxide, 0 - 10 wt% of sodium carbonate, and 0 - 5 wt% of limestone powder respectively.

[0012] In step (2), the calcination temperature in the high-temperature furnace is 1000°C - 1100°C.

[0013] In step (3), the specific surface area of the fluorite tailings-based geopolymer precursor obtained is below 100 m 2 / kg.

[0014] Step (4) is specifically as follows: Place the fluorite tailings-based geopolymer precursor powder in a stirring pot and mix it at a water-binder ratio of 0.3. After mixing evenly, put it into a 20 mm × 20 mm × 20 mm square mold for molding. After demolding after 24 h of film-covered curing, test its compressive strength at 7 d, 28 d, and 56 d of curing.

[0015] Adopting the above technical solution, compared with the prior art, the beneficial effects of the technical solution of the present invention are as follows: As a solid waste, fluorite tailings are ground and then added with sodium hydroxide, sodium carbonate, and lime powder for calcination, and the activity can be excited at a relatively low temperature to obtain a geopolymer precursor with certain strength after hydration. The compressive strength test of the obtained fluorite tailings-based geopolymer precursor powder shows good compressive strength. The present invention has the advantages of simple and easily available raw materials, low calcination temperature, and less carbon emission, providing a new idea for the resource utilization of fluorite tailings. Description of the Drawings

[0016] Figure 1 is the microscopic morphology of the Y15 geopolymer precursor;

[0017] Figure 2 is the microscopic morphology of the hydration products of the Y15 geopolymer precursor;

[0018] Figure 3 is the XRD diffraction pattern of fluorite tailings, Y11, and the hydration products of Y11;

[0019] Figure 4 is the XRD diffraction pattern of fluorite tailings, Y15, and the hydration products of Y15;

[0020] Figure 5 is the infrared spectrum of fluorite tailings, Y11, and the hydration products of Y11;

[0021] Figure 6 is the infrared spectrum of fluorite tailings, Y15, and the hydration products of Y15. Embodiments

[0022] The present invention will be further described in detail below in conjunction with specific embodiments.

[0023] In the following examples, the fluorite tailings used were taken from a mine in Luoyang, Henan. Their initial particle size was 50 - 500 μm, the specific surface area was 22.83 m 2 / kg, and the bulk density was 1.29 g / cm 3 ; the sodium hydroxide was laboratory analytical pure sodium hydroxide; the sodium carbonate was analytical pure anhydrous sodium carbonate; the limestone powder was commercially available analytical pure calcium hydroxide in the form of fine powder.

[0024] Example 1:

[0025] A preparation method of a geological polymer precursor based on fluorite tailings includes the following steps: The fluorite tailings are dried in an oven at 105 °C for 24 h, then cooled, placed in a ball mill for grinding, and passed through an 80-μm square-hole sieve to obtain fluorite tailings powder. The fluorite tailings powder is mixed with sodium hydroxide, sodium carbonate, and lime powder in a certain proportion, placed in a high-temperature sintering furnace, heated to 1000 °C at a rate of 5 °C per minute, held at 1000 °C for 30 min, and then cooled to room temperature. The calcined product is crushed and ground in a ball mill to obtain a geological polymer precursor based on fluorite tailings. The powder of the geological polymer precursor based on fluorite tailings is placed in a stirring pot and mixed at a water-binder ratio of 0.3, and after mixing evenly, it is formed into a 20 mm × 20 mm × 20 mm square mold, demolded after film curing for 24 h, and its compressive strength at 7 d, 28 d, and 56 d of curing is tested (the raw material ratios and compressive strength tests of Example 1 are shown in Table 1).

[0026] Table 1

[0027]

[0028] Example 2:

[0029] A preparation method of a geological polymer precursor based on fluorite tailings includes the following steps: The fluorite tailings are dried in an oven at 105 °C for 24 h, then cooled, placed in a ball mill for grinding, and passed through an 80-μm square-hole sieve to obtain fluorite tailings powder. The fluorite tailings powder is mixed with sodium hydroxide, sodium carbonate, and lime powder in a certain proportion, placed in a high-temperature sintering furnace, heated to 1050 °C at a rate of 5 °C per minute, held at this temperature for 30 min, and then cooled to room temperature. The product is crushed and ground in a ball mill to obtain a geological polymer precursor based on fluorite tailings. The ground powder is placed in a stirring pot and mixed at a water-binder ratio of 0.3, and after mixing evenly, it is formed into a 20 mm × 20 mm × 20 mm square mold, demolded after film curing for 24 h, and its compressive strength at 7 d, 28 d, and 56 d of curing is tested (the raw material ratios and compressive strength tests of Example 2 are shown in Table 2).

[0030] Table 2

[0031]

[0032] Example 3:

[0033] A preparation method of a geological polymer precursor for fluorite tailings base, comprising the following steps: The fluorite tailings are dried in an oven at 105 °C for 24 h and then cooled, placed in a ball mill for grinding, and passed through an 80-μm square-hole sieve to obtain fluorite tailings powder. The fluorite tailings powder is mixed with sodium hydroxide, sodium carbonate, and lime powder in a certain proportion, placed in a high-temperature sintering furnace, heated to 1100 °C at a rate of 5 °C per minute, maintained at this temperature for 30 min, and cooled to room temperature. The product is crushed and ground in a ball mill to prepare a geological polymer precursor for fluorite tailings base. The ground powder is placed in a stirring pot and mixed at a water-binder ratio of 0.3, and after mixing evenly, it is formed into a 20 mm × 20 mm × 20 mm square mold, demolded after film curing for 24 h, and its compressive strength at 7 d, 28 d, and 56 d of curing is tested (the raw material ratios and compressive strength tests of Example 3 are shown in Table 3).

[0034] Table 3

[0035]

[0036] In the above three examples, as Figures 1-6 shown, during the calcination process, components such as feldspar in the fluorite tailings produced an amorphous glass phase under the action of alkali activation, and the reaction activity was significantly improved, which can be used as a precursor for the geological polymer base. In the compressive strength test, the geological polymer precursor for fluorite tailings base can undergo a polymerization reaction in water to generate strength phases such as hydrated sodium (calcium) silicate gel, thus showing a certain strength.

[0037] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a geological polymer precursor for fluorite tailings base, Characterized in that: It includes the following steps, (1) Grind the fluorite tailings; (2) Mix the ground fluorite tailings, sodium hydroxide, sodium carbonate, and lime powder evenly in a certain proportion, and place them in a high-temperature furnace for calcination to form a fluorite tailings mixed powder; (3) Grind the calcined and naturally cooled fluorite tailings mixed powder to obtain the geological polymer precursor for fluorite tailings base; (4) Test the compressive strength of the geological polymer precursor for fluorite tailings base; The specific surface area of the fluorite tailings after grinding in step (1) is below 100 m 2 / kg; The proportions of fluorite tailings, sodium hydroxide, sodium carbonate, and lime powder in step (2) are 50-80 wt% of fluorite tailings, 10-50 wt% of sodium hydroxide, 0-10 wt% of sodium carbonate, and 0-5 wt% of limestone powder respectively; The calcination temperature in the high-temperature furnace in step (2) is 1000 °C - 1100 °C.

2. A preparation method of a geological polymer precursor for fluorite tailings base according to claim 1, Characterized in that: The specific surface area of the fluorite tailings geopolymer precursor prepared in step (3) is below 100 m 2 / kg.

3. A preparation method of a geological polymer precursor for fluorite tailings base according to claim 1, Characterized in that: Step (4) is specifically: Place the powder of the geological polymer precursor for fluorite tailings base in a stirring pot and mix it at a water-binder ratio of 0.

3. After mixing evenly, put it into a 20mm×20mm×20mm square mold for molding. After demolding after 24h of film-covered curing, test its compressive strength at 7d, 28d, and 56d of curing.

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