Mine filling cementing material and preparation method thereof

Abstract

The invention discloses a mine filling cementing material and a preparation method thereof. The mine filling cementing material comprises the following components in percentage by mass: 3-8 wt% of high belite sulphoaluminate cement clinker; 1-3 wt% of high free calcium silicate cement clinker; 74 to 85 wt% of granulated blast furnace slag powder or granulated blast furnace slag; and 10 to 18 wt% of gypsum. Compared with other paste filling materials with the same strength, the cementing material solves the problems that in the prior art, a mine filling cementing material is poor in excitation effect and poor in mechanical property, so that the mine filling effect is affected, and the cost is high due to the fact that the using amount of the cementing material is large, and meanwhile the using proportion is reduced; and the use of mine backfill engineering is fully met.

Description

Technical Field

[0001] The invention relates to the technical field of mine filling, and in particular to a mine filling gelling material and a preparation method thereof. Background Art

[0002] Paste filling mining technology is used in metal and non-metal mining. This technology is to prepare solid waste into a paste slurry that does not require dehydration, transport it to the underground goaf through a material transportation system, and open the goaf in a timely and appropriate amount. This technology has the following advantages: first, it protects safety and improves the safety of mine mining; second, it protects resources and improves the recovery rate of mine resources; third, it protects the environment, reduces the degree of damage to the surface caused by mining, and reduces the discharge of solid waste from mines.

[0003] Cementitious materials are needed to make paste slurry. GB / T 51450-2022 "Technical Standard for Metal and Non-metal Mining Backfill Engineering" defines cementitious materials as: materials that can be transformed from slurry into solid stone-like bodies under physical and chemical effects, and can cement other materials to form composite solids with certain mechanical strength. NB / T11434.5-2023 "Coal Mine Paste Backfill Part 5: Technical Requirements for Cementitious Materials" defines cementitious materials as: mixed materials with hydraulic properties made by mixing materials with potential hydraulic properties, activated materials, and other functional auxiliary materials, including but not limited to general-purpose silicate cement (silicon cement, ordinary silicate cement, slag silicate cement, volcanic ash silicate cement, fly ash silicate cement and composite silicate cement), medium-heat silicate cement, low-heat silicate cement, masonry cement, steel slag silicate cement, magnesium slag silicate cement, alkali slag cementitious materials, gypsum slag cementitious materials, lime volcanic cementitious materials, geopolymer cementitious materials, etc. In order to reduce costs and dispose of solid waste, clinker-free or low-clinker cement is widely used.

[0004] CN 114940600 A discloses a full solid waste filling material and a preparation method thereof. The gel material includes desulfurized gypsum, fly ash, slag, steel slag, magnesium slag, carbide slag, water reducing agent, water retaining dispersant and alkaline activator; the aggregate is tailings, and the beneficial effects are: the theory of synergistic complementation of multi-source solid waste chemical components is reasonably utilized. Under the action of the alkaline activator, the silicon-rich phase and calcium-rich phase in the slag and fly ash structure react to generate AFm crystals with higher strength under the action of alkali excitation. The water retaining dispersant reasonably solves the segregation and water seepage problems of the full solid waste filling material, so that the filling material has good water retention and uniform dispersibility; an appropriate amount of fly ash is added, and the fly ash can exert a ball effect to increase the fluidity of the filling slurry. This technology uses full solid waste to make gelling materials, and uses multiple excitation technologies of alkali excitation and sulfate excitation.

[0005] CN202110267272.8 discloses a cement-based filling material containing a variety of solid wastes, and its preparation method and application. The filling material of the present invention is composed of the following raw materials in percentage by mass: 5%-14% desulfurized gypsum, 22%-35% fly ash, 24%-35% water-quenched slag, 5%-6% cement and 25wt%-35% tap water. By using three solid wastes, desulfurized gypsum, fly ash and water-quenched slag, and a small amount of cement to prepare the filling body, the environmental pollution problem caused by the storage of solid wastes is solved. At the same time, the solid waste, cement and water in the filling material undergo hydration reaction to generate a large amount of hydration products, thereby forming a filling body with high strength, which can meet the strength required for underground mining filling bodies. This technology uses desulfurized gypsum as sulfate excitation, cement is ordinary silicate cement (strength grade 42.5R or 52.5), and calcium hydroxide produced during the hydration of ordinary cement is used as alkali excitation. Overall, it has a certain excitation effect, but the excitation effect is also far lower than the existing advanced level. As a filling material, the efficiency of solid materials is very low.

[0006] In recent years, a new type of super-sulfated cement has emerged. On the basis of the original gypsum slag cement, special cement clinker high belite sulphoaluminate clinker is added as an activating material, which greatly improves the activating effect of slag, greatly improves the early and late strength of cement, and produces the standard T / CBMF 192-2022 "Slag Sulphoaluminate Cement". This cement is made of sulphoaluminate cement clinker, granulated blast furnace slag and anhydrite, and is a hydraulic cementitious material with low hydration heat and high flexural strength. Among them, the sulphoaluminate cement clinker is mainly composed of anhydrous calcium sulphoaluminate and dicalcium silicate, wherein the sum of the content of anhydrous calcium sulphoaluminate and dicalcium silicate (mass fraction) should not be less than 60%, and the content of anhydrous calcium sulphoaluminate (mass fraction) should not be less than 25wt%, and the content of dicalcium silicate (mass fraction) should not be less than 25wt%. Sulphoaluminate cement clinker 2-10wt%, anhydrite 8-25%, granulated blast furnace slag (powder) 65-90%.

[0007] In the filling project of metal and non-metal mines, according to the characteristics of the new super-sulfate cement, slag sulphoaluminate cement is considered to be used as a cementitious material, in order to achieve the purpose of low cement material dosage, simple filling process and thus reduce costs. However, in actual use, it is found that due to the small ash-sand ratio, sometimes reaching 1:11 or even lower, the water-binder ratio is also very large, usually greater than 4.7, and the small fineness of the tailings, the early and late strength of the filling paste is significantly reduced. Summary of the invention

[0008] The purpose of the present invention is to provide a mine filling cementitious material and a preparation method thereof, so as to solve the problems in the prior art of poor excitation effect of mine filling cementitious materials, poor mechanical properties affecting mine filling effect, and large amount of cementitious materials used resulting in high costs.

[0009] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0010] In one aspect, a mine filling cementitious material is provided, comprising the following components in a mass ratio:

[0011] High belite sulphoaluminate cement clinker: 3-8wt%;

[0012] High free calcium silicate cement clinker: 1-3wt%;

[0013] Granulated blast furnace slag powder or granulated blast furnace slag: 74-85wt%;

[0014] Gypsum: 10-18wt%.

[0015] Furthermore, the mineral composition of the high-belite sulphoaluminate cement clinker includes C2S, C4AF, CaSO4 and f-CaO, among which The sum of the mass fractions of C2S is ≥ 60wt%, and The mass fraction of C2S is ≥25wt%, the mass fraction of C4AF is 1-10wt%, the mass fraction of CaSO4 is 2-24wt%, and the mass fraction of f-CaO is 0-3wt%.

[0016] Furthermore, the mineral composition of the high free calcium silicate cement clinker includes f-CaO, C3S, C2S, C3A, C4AF and CaSO4, among which the mass fraction of f-CaO is 42-55wt%, The mass fraction of is 0-3wt%, the sum of the mass fractions of C3S and C2S is 22-45wt%, the sum of the mass fractions of C3A and C4AF is 5-20wt%, and the mass fraction of CaSO4 is 0-3wt%.

[0017] Furthermore, the granulated blast furnace slag powder meets the quality requirements of GB / T 18046-2017 "Granulated blast furnace slag powder for cement, mortar and concrete", and the grade is S95.

[0018] Furthermore, the granulated blast furnace slag meets the quality requirements of GB / T 203 "Granulated blast furnace slag for cement".

[0019] Furthermore, the gypsum includes at least one of dihydrate gypsum, anhydrite, desulfurized gypsum and phosphogypsum.

[0020] Furthermore, the desulfurized gypsum or the phosphogypsum needs to be modified, specifically by calcining in an environment of 600-800° C. for 10-20 min.

[0021] On the other hand, a method for preparing a mine filling cementitious material is provided, wherein high belite sulphoaluminate cement clinker, high free calcium silicate cement clinker, granulated blast furnace slag powder or granulated blast furnace slag, and gypsum are ground separately, weighed according to a mass ratio, and then uniformly mixed; or high belite sulphoaluminate cement clinker, high free calcium silicate cement clinker, granulated blast furnace slag powder or granulated blast furnace slag, and gypsum are weighed according to a mass ratio, mixed uniformly, and ground to a specific surface area of ​​≥420m 2 / kg, to obtain mine filling cementitious material.

[0022] Furthermore, high-belite sulphoaluminate cement clinker, high free calcium silicate cement clinker, granulated blast furnace slag powder or granulated blast furnace slag and gypsum are ground separately, weighed according to the mass ratio and then uniformly mixed to obtain the mine filling cementitious material.

[0023] Furthermore, the specific surface area of ​​the high-belite sulphoaluminate cement clinker after grinding is ≥420m 2 / kg, the specific surface area of ​​the high free calcium silicate cement clinker after grinding is ≥380m 2 / kg, the specific surface area of ​​the granulated blast furnace slag powder or the granulated blast furnace slag powder after grinding is ≥420m 2 / kg, the specific surface area of ​​the gypsum powder after grinding is ≥420m 2 / kg.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The cement clinker used in the cementitious material of the present invention is used in a small amount. Generally, the most suitable dosage is about 7%, and the carbon emission is low.

[0026] 2. The activity of the slag used in the cementitious material of the present invention can be effectively stimulated, which is manifested in a significant increase in early and late strength. The strength can be increased by at least 50% on the basis of the existing technical level, and the amount of cementitious material used in the paste material to achieve the same filling strength is greatly reduced, which saves the amount of cementitious material used and is conducive to cost saving.

[0027] 3. The raw material components of the cementitious material of the present invention are relatively few, the sources are rich, and the production and use are relatively simple. When the cementitious material is used to prepare the paste filling material, the mixing property is good, the early strength develops quickly, and the later strength can also increase steadily. The amount of admixture used can be reduced or not used. For places with relatively poor resources around mines, such as lack of fly ash, steel slag, magnesium slag, silicon manganese slag, etc., raw materials are easy to obtain and production is more flexible.

[0028] 4. The cementitious material of the present invention is prepared by mixing granulated blast furnace slag powder or granulated blast furnace slag with cement clinker and gypsum. During the hydration reaction, due to the appropriate concentration and alkalinity of each ion in the hydration environment, the formation of ettringite is relatively rapid; at the same time, the dissolution rate of ions in the glass body of the granulated blast furnace slag powder or granulated blast furnace slag is also accelerated, and the ettringite particles formed after the dissolved ions in the glass body participate in the reaction are filled into the skeleton of the unreacted ions, wrapping and interlacing with each other to form a dense structure, so that the early strength and the later strength are much higher than the early strength of the cementitious material activated by other industrial waste slag, and the setting and hardening time is also greatly shortened. In the early stage, the f-CaO in the high-belite sulphoaluminate cement clinker and the high-free calcium silicate cement clinker is hydrated to generate calcium hydroxide to provide a suitable alkaline environment, the hydration of the high-belite sulphoaluminate cement clinker is accelerated, and the formation of calcium sulfonate is relatively rapid. The main hydration products are AFt and a small amount of CSH gel; in the later stage, the granulated blast furnace slag powder or granulated blast furnace slag continues to hydrate, and CSH, a small amount of hydrotalcite and other hydrates are filled into the early hydrates to improve the density, thereby further improving the later strength and showing excellent mechanical properties. Compared with other paste filling materials of the same strength, the use ratio of the cementitious material of the present invention is also greatly reduced, which fully meets the use of mine backfill engineering. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0030] In the implementation of the present invention, the mineral composition of high-belite sulphoaluminate cement clinker includes 28.5wt%, C2S: 46.2wt%, C4AF: 3.5wt%, CaSO4: 8.7wt%, f-CaO: 2.4wt%.

[0031] In the implementation of the present invention, the mineral composition of the high free calcium silicate cement clinker includes f-CaO: 47.2wt%, C2S+C3S: 27.2wt%, 2.1wt%, C3A+C4AF: 17.6wt%, CaSO4: 0.5wt%.

[0032] In the implementation of the present invention, the granulated blast furnace slag meets the quality requirements of GB / T 18046-2017 "Granulated blast furnace slag powder for cement, mortar and concrete".

[0033] In the implementation of the present invention, the anhydrite is commercially available anhydrite.

[0034] In the embodiment of the present invention, the specific surface area of ​​the high-belite sulphoaluminate cement clinker after grinding is ≥420m 2 / kg, the specific surface area of ​​high free calcium silicate cement clinker after grinding is ≥380m 2 / kg, the specific surface area of ​​granulated blast furnace slag powder after grinding is ≥420m 2 / kg, the specific surface area of ​​anhydrite after grinding is ≥420m 2 / kg.

[0035] Example 1

[0036] As a preferred embodiment of the present invention, the specific composition of the mine filling cementitious material of this embodiment is shown in Table 1 below:

[0037] Table 1

[0038]

[0039]

[0040] High-belite sulphoaluminate cement clinker, high free calcium silicate cement clinker, granulated blast furnace slag powder and anhydrite are ground separately, weighed according to the mass ratio shown in Table 1, and then uniformly mixed to obtain the mine filling cementitious material of this embodiment.

[0041] Example 2

[0042] As a preferred embodiment of the present invention, the specific composition of the mine filling cementitious material of this embodiment is shown in Table 2 below:

[0043] Table 2

[0044] Components Mass ratio (wt%) High Belite Sulphoaluminate Cement Clinker 3.50 High free calcium silicate cement clinker 1.50 Granulated blast furnace slag powder 80.00 Anhydrite 15.00

[0045] High-belite sulphoaluminate cement clinker, high free calcium silicate cement clinker, granulated blast furnace slag powder and anhydrite are ground separately, weighed according to the mass ratio shown in Table 2, and then uniformly mixed to obtain the mine filling cementitious material of this embodiment.

[0046] Comparative Example 1

[0047] The specific composition of the cementitious material of this comparative example is shown in Table 3, and the rest is the same as that of Example 1.

[0048] Table 3

[0049] Components Mass ratio (wt%) High Belite Sulphoaluminate Cement Clinker 2.00 High free calcium silicate cement clinker 1.50 Granulated blast furnace slag powder 81.50 Anhydrite 15.00

[0050] Comparative Example 2

[0051] The specific composition of the cementitious material of this comparative example is shown in Table 4, and the rest is the same as that of Example 1.

[0052] Table 4

[0053] Components Mass ratio (wt%) High Belite Sulphoaluminate Cement Clinker 8.50 High free calcium silicate cement clinker 1.50 Granulated blast furnace slag powder 75.00 Anhydrite 15.00

[0054] Comparative Example 3

[0055] The specific composition of the cementitious material of this comparative example is shown in Table 5, and the rest is the same as that of Example 1.

[0056] Table 5

[0057] Components Mass ratio (wt%) High Belite Sulphoaluminate Cement Clinker 3.50 High free calcium silicate cement clinker 4.50 Granulated blast furnace slag powder 77.00 Anhydrite 15.00

[0058] Comparative Example 4

[0059] The specific composition of the cementitious material of this comparative example is shown in Table 6, and the rest is the same as that of Example 1.

[0060] Table 6

[0061] Components Mass ratio (wt%) High Belite Sulphoaluminate Cement Clinker 3.50 High free calcium silicate cement clinker 0.50 Granulated blast furnace slag powder 81.00 Anhydrite 15.00

[0062] Comparative Example 5

[0063] The cementitious material of this comparative example is commercially available P·O 42.5 cement.

[0064] Test Example 1

[0065] According to T / MMAC 005-2022 "Cementitious materials for cementing and filling whole tailings in metal mines" and GB / T 17671-2021 "Test method for strength of cement mortar (ISO method)", the cementitious materials of each embodiment and comparative example were molded into mortar specimens, and the compressive strength of the mortar was tested. The test results are shown in Table 7 below.

[0066] Table 7

[0067]

[0068] According to the test results in Table 7, it can be seen that:

[0069] (1) The early strength of the cementitious material of the embodiment of the present invention is relatively high. When the proportion of high-belite sulphoaluminate cement clinker used is relatively large (Comparative Example 2), the hydrated calcium sulfonate produced by the initial hydration is too much wrapped on the surface of the slag powder, which retards the further hydration of the slag powder; when the proportion of high-belite sulphoaluminate cement clinker used is relatively small (Comparative Example 1), the excitation effect is relatively weak, resulting in the inability to effectively excite the activity of the slag powder, resulting in low early and late strengths.

[0070] (2) Since the mortar of the paste filling material is relatively small, its tailings are usually finer and the alkalinity in the hydration environment is relatively low. Therefore, a high free calcium silicate cement clinker is used for adjustment. However, if the usage ratio is too large (Comparative Example 3), the early strength is improved, but the later strength growth is inhibited. If the usage is too small (Comparative Example 4), the early and late excitation effects will appear less than ideal.

[0071] (3) Comparative Example 5 uses the existing gel material - ordinary Portland cement P·O 42.5 cement. Its later strength development is not as good as that of the embodiment of the present invention. At the same time, its clinker usage is higher than that of the embodiment.

[0072] Test Example 2

[0073] The filling body test block was prepared according to GB / T 51450-2022 "Technical Standards for Metal and Non-metal Mining Filling Engineering": Specifically, the cementitious material (dosage 6.4wt%) of each embodiment and comparative example was mixed evenly with phosphate tailings (dosage 63.6wt%) and water (dosage 30.0wt%), and the mold was vibrated to obtain a paste filling material. The phosphate tailings are phosphate tailings, with a water content of 26wt%, and the weight percentages of the main mineral components are: dolomite: 74.2wt%, quartz: 2.1wt%, fluoroapatite: 13.3wt%, calcite: 0.7wt% and ankerite: 9.7wt%.

[0074] The compressive strength of each paste filling material was tested according to the methods in JGJ / T 70-2009 "Standard for Test Methods for Basic Properties of Building Mortar", T / MMAC 005-2022 "Metal Mine Tailings Cementitious Filling Cementitious Materials" and NB / T 51070-2017 "Test Methods for Coal Mine Paste Filling Materials". The test results are shown in Table 8 below.

[0075] Table 8

[0076]

[0077] According to the test results in Table 8:

[0078] The high-belite sulphoaluminate cement clinker added to the cementitious material in Comparative Examples 1 and 2 is too small or too large, and its performance is far inferior to that of the embodiment; the high-free calcium silicate cement clinker added to the cementitious material in Comparative Examples 3 and 4 is too large or too small, and its performance is also inferior to that of the embodiment. The excitation effect of Comparative Examples 1 to 4 is weaker than that of Examples 1 and 2, and the mechanical properties of the paste filling materials configured in Examples 1 and 2 are better than those of Comparative Examples 1 to 4. And compared with Comparative Example 5, the later mechanical properties of the paste filling materials configured in Examples 1 and 2 are also better than those of the paste filling materials prepared by the existing gel materials. At the same time, the amount of clinker used in the glue material is very small, which is conducive to cost saving. For this reason, the cementitious material provided by the present invention can improve the problem of poor early and late mechanical properties of general filling materials. At the same time, the material source is abundant, easy to prepare, and the cost saving is significant.

[0079] Finally, it should be noted that the above embodiments are only preferred embodiments of the present invention to illustrate the technical solutions of the present invention, rather than limiting them, and certainly not limiting the patent scope of the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention. In other words, any changes or modifications made to the main design concept and spirit of the present invention that have no substantive significance, and the technical problems they solve are still consistent with the present invention, should be included in the protection scope of the present invention. In addition, the direct or indirect application of the technical solutions of the present invention in other related technical fields is also included in the patent protection scope of the present invention.

Claims

1. A mine filling cementitious material, characterized in that: The following components are included in mass ratio: High belite sulphoaluminate cement clinker: 3-8wt%; High free calcium silicate cement clinker: 1-3wt%; Granulated blast furnace slag powder or granulated blast furnace slag: 74-85wt%; Gypsum: 10-18wt%.

2. A mine filling cementitious material according to claim 1, characterized in that: The mineral composition of the high-belite sulphoaluminate cement clinker includes C2S, C4AF, CaSO4 and f-CaO, among which The sum of the mass fractions of C2S is ≥ 60wt%, and The mass fraction of C2S is ≥25wt%, the mass fraction of C4AF is 1-10wt%, the mass fraction of CaSO4 is 2-24wt%, and the mass fraction of f-CaO is 0-3wt%.

3. A mine filling cementitious material according to claim 1, characterized in that: The mineral composition of the high free calcium silicate cement clinker includes f-CaO, C3S, C2S, C3A, C4AF and CaSO4, among which the mass fraction of f-CaO is 42-55wt%, The mass fraction of is 0-3wt%, the sum of the mass fractions of C3S and C2S is 22-45wt%, the sum of the mass fractions of C3A and C4AF is 5-20wt%, and the mass fraction of CaSO4 is 0-3wt%.

4. A mine filling cementitious material according to claim 1, characterized in that: The granulated blast furnace slag powder meets the quality requirements of GB / T 18046-2017 "Granulated blast furnace slag powder for cement, mortar and concrete" and is grade S95.

5. The mine filling cementitious material according to claim 1, characterized in that: The granulated blast furnace slag meets the quality requirements of GB / T 203 "Granulated blast furnace slag for cement".

6. The mine filling cementitious material according to claim 1, characterized in that: The gypsum includes at least one of dihydrate gypsum, anhydrite, desulfurized gypsum and phosphogypsum.

7. A mine filling cementitious material according to claim 6, characterized in that: The desulfurized gypsum or the phosphogypsum needs to be modified, specifically by calcining in an environment of 600-800° C. for 10-20 minutes.

8. A method for preparing a mine filling cementitious material according to any one of claims 1 to 7, characterized in that: Grind high belite sulphoaluminate cement clinker, high free calcium silicate cement clinker, granulated blast furnace slag powder or granulated blast furnace slag and gypsum separately, weigh them according to the mass ratio and mix them evenly, or weigh high belite sulphoaluminate cement clinker, high free calcium silicate cement clinker, granulated blast furnace slag powder or granulated blast furnace slag and gypsum according to the mass ratio and mix them evenly and grind them to a specific surface area of ​​≥420m 2 / kg, to obtain mine filling cementitious material.

9. The method for preparing a mine filling gelling material according to claim 8, characterized in that: High-belite sulphoaluminate cement clinker, high free calcium silicate cement clinker, granulated blast furnace slag powder or granulated blast furnace slag and gypsum are ground separately, weighed according to the mass ratio and then uniformly mixed to obtain a mine filling cementitious material.

10. The method for preparing a mine filling gelling material according to claim 9, characterized in that: The specific surface area of ​​the high-belite sulphoaluminate cement clinker after grinding is ≥420m 2 / kg, the specific surface area of ​​the high free calcium silicate cement clinker after grinding is ≥380m 2 / kg, the specific surface area of ​​the granulated blast furnace slag powder or the granulated blast furnace slag powder after grinding is ≥420m 2 / kg, the specific surface area of ​​the gypsum powder after grinding is ≥420m 2 / kg.

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