Preparation method of cementing material admixture

Abstract

The invention discloses a preparation method of a cementing material admixture, which is characterized in that the liquidity of mixed slurry is higher by controlling the liquid-solid ratio, so that the heat transfer and mass transfer effects are better; through cooperative control of heating temperature and heat preservation time, uniform and sufficient reaction of active components in slag or mill tailings and lime is facilitated, due to complete reaction of the active components, the yield is increased, the possibility of alkali-aggregate reaction of the active components and the remaining activating agent in the use stage is reduced as much as possible, and the service life of the active components is prolonged. Great influence on the strength and the service life of the material is avoided; meanwhile, due to control over the upper limit of the heating temperature, inert materials in the slag or the mill tailings exist as aggregates, the material strength can be improved, and the cost can be reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of harmless treatment and resource utilization of industrial solid waste, and specifically relates to a method for preparing a cementitious material admixture. Background Art

[0002] In the process of metal smelting, fuel combustion, coal / oil catalytic conversion, etc., components containing Si, Al, Ca, Mg, Na, K, etc. are melted or decomposed at high temperature, converted into highly active structural disordered components and discharged in the form of slag (including bottom slag and fly ash). In the presence of water, acidic components such as Si and Al in the slag can react chemically with alkaline components such as Ca, Mg, Na, K to generate cementitious products such as hydrated calcium silicate and zeolite. Therefore, slag is widely used in the preparation of alkali-activated cementitious materials.

[0003] The Chinese patent document with publication number CN116496009A discloses a method for preparing a superfine tailings filling cementitious material mainly composed of copper slag and fly ash, wherein the cementitious material comprises 30-50 parts of copper slag powder, 20-40 parts of fly ash, 15-20 parts of cement clinker, 6-13 parts of high-strength gypsum powder, 2-4 parts of alkaline activator (NaOH, Ca(OH) 2 ), the 28d compressive strength of the filling material made by mixing cementitious materials and ultrafine tailings exceeds 0.8MPa. Adding alkaline activator can fully release the activity of copper slag and improve the strength of the filling body, but in the later stage, the filling body will show surface weathering and internal cracks; reducing the proportion of NaOH and increasing Ca(OH) 2 After the proportion was adjusted, the surface weathering and internal cracks of the filling body were significantly reduced.

[0004] A Chinese patent document with publication number CN116768503A discloses a coal-based solid waste-based cementitious material, a derived high-performance concrete and a preparation method, which uses 30% calcined coal gangue, 30-40% fly ash and bottom slag, 20% coal gasification ash, and 10-20% mineral powder as precursors, 4-12% sodium silicate solution and 13-27% straw ash as alkali activators, and 0.05-0.20% shrinkage reducer and 60% water as a mixing aqueous solution. The 3d compressive strength of the prepared cementitious material exceeds 10MPa; the compressive strength of the derived high-performance concrete gradually increases with the increase of the alkali activator content in the cementitious material.

[0005] The Chinese patent document with publication number CN111978099B discloses an aerated concrete and a preparation method thereof, comprising 5 to 15 parts of lime, 10 to 30 parts of converter slag, 60 to 70 parts of fly ash, 0 to 5 parts of gypsum, 0 to 0.5 parts of aluminum powder paste, 0 to 0.5 parts of a foaming agent and other raw materials, and the apparent density of the prepared aerated concrete is less than 690 kg / m 3The average compressive strength exceeds 8.8MPa. The calcium components in lime and converter slag react with the silicon components in fly ash to form cementitious products such as hydrated calcium aluminosilicate and hydrated calcium silicate, which make the aerated concrete have a higher strength.

[0006] The Chinese patent document with publication number CN116621543A discloses a method for preparing a composite titanium tailings-based calcium silicate board, wherein titanium tailings, silicate cement, siliceous raw materials, calcareous raw materials and wood fiber are mixed in a certain ratio to prepare a wet blank, and then cured at normal pressure for 6 to 36 hours and then autoclaved at 120 to 200°C for 4 to 12 hours to obtain the calcium silicate board. Silicon and calcium components account for more than 50% of the mass percentage of titanium tailings, so the use of titanium tailings can reduce the amount of other siliceous and calcareous raw materials and reduce the production cost of calcium silicate boards. The amount of titanium tailings can reach more than 40%.

[0007] The method disclosed in the above patent document utilizes the characteristic of slag having high reactivity, and directly mixes slag with materials such as alkaline activators to prepare cementitious materials, concrete, building materials and other products. Although the alkaline activator can react with the active components in the slag to generate cementitious products such as hydrated calcium silicate and hydrated calcium aluminosilicate, the material molding time is short, resulting in a slow reaction rate between the alkaline activator and the active components of the slag, and a long curing time is required for the material to form a higher strength. If the active components in the slag have not reacted completely (the activity has not been fully released) after the material has formed strength, it will also cause alkali-aggregate reaction and destroy the later strength of the material. For example, the common cracking of concrete and building materials is a phenomenon of later strength destruction of the material caused by alkali-aggregate reaction. Summary of the invention

[0008] The invention provides a method for preparing a cementitious material admixture, which can prepare a cementitious material admixture with higher strength at a suitable cost.

[0009] The present invention provides a method for preparing a cementitious material admixture, comprising:

[0010] S1. According to a Ca / Si molar ratio of 0.1-1.0 and a liquid-to-solid ratio of 3-15 mL / g, slag, lime, activator and water are mixed to obtain a mixed slurry;

[0011] S2, injecting the mixed slurry into a sealed container, stirring evenly, and then heating to 30-120° C., keeping warm for 0.1-10 hours, to obtain a reaction product;

[0012] S3, separating the reaction product into solid and liquid, and obtaining a solid product as a cementitious material admixture.

[0013] The present invention provides a suitable liquid-solid ratio so that the mixed slurry has good fluidity and a good mass transfer effect. If the water content is low, it is easy to cause uneven reaction, local overreaction or no reaction, and low yield.

[0014] Since the present invention provides a higher liquid-to-solid ratio, the present invention can fully dissolve and convert the active components such as Si, Al, Ca, Mg, Na, K and other active components in the slag into aluminosilicate cementitious products, i.e., hydrated calcium silicate and / or zeolite products, at a lower temperature and with a lower Ca content. At the same time, since the active components in the slag react completely, the possibility of alkali-aggregate reaction between the residual activator and the active components is low. At the same time, the heating time and insulation time provided by the present invention can also retain the inert material in the slag as a skeleton, thereby improving the strength of the cementitious material admixture. If the heating temperature is too high, the inert material will dissolve and the strength will decrease significantly.

[0015] Preferably, the Ca / Si molar ratio is 0.2-0.6. At present, the most widely used cementitious materials are cement-based materials. In the process of hydration reaction of cement-based materials to form a cementitious body, free calcium will be produced. In the dry / wet alternating environment, this free calcium will alternately form calcium oxide or calcium hydroxide, which will produce a shrinkage / expansion effect in the cementitious body, thereby destroying the strength of the cementitious body. The cementitious material admixture prepared under the condition of a lower Ca / Si molar ratio of the present invention can combine the free calcium produced in the cement hydration process to form a hydration product with a higher Ca / Si molar ratio, avoid the formation of calcium oxide or calcium hydroxide in the cementitious body, and then avoid the volume shrinkage / expansion effect, thereby improving the comprehensive performance of the cementitious material such as strength and service life; but too low a Ca / Si molar ratio (Ca / Si molar ratio is less than 0.1) will lead to incomplete reaction of the active components in the slag, reduce the content of the effective components of the cementitious material admixture, and reduce the comprehensive performance of the cementitious material admixture to a certain extent. Therefore, it is recommended that the appropriate Ca / Si molar ratio is 0.2-0.6.

[0016] Preferably, the liquid-to-solid ratio is 5-10 mL / g. A liquid-to-solid ratio lower than 5 mL / g will make the mixed slurry more viscous and have poor fluidity, reduce the effect of heat and mass transfer, and then induce local reactions, reducing the comprehensive performance of the cementitious material admixture; a liquid-to-solid ratio higher than 10 mL / g can make the cementitious material admixture obtain better comprehensive performance, but it will reduce production efficiency and increase production costs.

[0017] Preferably, the stirring linear speed is 100-300 m / s.

[0018] More preferably, the liquid-to-solid ratio is 8-15 mL / g, and the linear speed of the stirring is 100-200 m / s.

[0019] When the liquid-solid ratio is high, the mixed slurry is relatively thin and has better fluidity. Therefore, the stirring linear speed can be controlled at a lower level, and the transfer effect is still good and the reaction is uniform.

[0020] More preferably, under the condition that the liquid-to-solid ratio is 3 to 8 mL / g, the linear speed of stirring is 200 to 300 m / s.

[0021] When the liquid-solid ratio is low, the mixed slurry is relatively viscous and the fluidity is relatively poor. Therefore, the stirring linear speed can be controlled at a higher level to ensure better transfer effect and uniform reaction.

[0022] Preferably, the activator is a water-soluble sodium salt or potassium salt.

[0023] Further preferably, the activator includes but is not limited to any one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium sulfate, potassium sulfate, sodium silicate, and potassium silicate.

[0024] Preferably, the Na in the mixed slurry + and K + The sum of the concentrations is 0.01~1.0mol / L.

[0025] Further preferably, the Na of the mixed slurry is + and K + The sum of the concentrations is 0.1-0.5 mol / L.

[0026] Preferably, the heating temperature is 80-100° C. The present invention further controls the heating temperature, which can improve the crystallization degree of calcium silicate hydrate and / or zeolite, and can also shorten the heat preservation time to improve production efficiency and reduce costs.

[0027] The present invention discloses a method for preparing a cementitious material admixture by utilizing slag, wherein relatively active components such as Si, Al, Ca, Mg, Na, and K in the slag are stabilized by using lime to convert them into hydrated calcium silicate and / or zeolite having certain cementitious properties. The reaction product can be used as a cementitious material admixture to prepare products such as filling materials, roadbed materials, and building materials.

[0028] Preferably, the liquid product obtained by solid-liquid separation is returned to the batching process as circulating water. + and / or K + The solution can be returned to the batching process for recycling.

[0029] The present invention also provides a method for preparing a cementitious material admixture, comprising:

[0030] S1. Mixing the beneficiation tailings, lime, an activator and water according to a Ca / Si molar ratio of 0.1-0.6 and a liquid-to-solid ratio of 3-15 mL / g to obtain a mixed slurry;

[0031] S2, injecting the mixed slurry into a closed container, stirring evenly, and then heating to 90-200° C., keeping the temperature for 0.1-10 hours, to obtain a reaction product;

[0032] S3, separating the reaction product into solid and liquid, and obtaining a solid product as a cementitious material admixture.

[0033] The present invention controls the liquid-to-solid ratio to improve the fluidity of the mixed slurry and make the reaction between the ore dressing tailings and lime more uniform. Since the activities of components such as Si, Al, Ca, Mg, Na, and K in the ore dressing tailings are relatively low, a lower Ca / Si molar ratio and a higher reaction temperature are required to produce a cementitious material admixture with better performance.

[0034] Preferably, the Ca / Si molar ratio is 0.2-0.4.

[0035] Preferably, the liquid-to-solid ratio is 5-10 mL / g.

[0036] Preferably, the stirring linear speed is 100-300 m / s.

[0037] More preferably, the liquid-to-solid ratio is 8-15 mL / g, and the linear speed of the stirring is 100-200 m / s.

[0038] More preferably, under the condition that the liquid-to-solid ratio is 3 to 8 mL / g, the linear speed of stirring is 200 to 300 m / s.

[0039] Preferably, the activator is a water-soluble sodium salt or potassium salt.

[0040] Further preferably, the activator includes but is not limited to any one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium sulfate, potassium sulfate, sodium silicate, and potassium silicate.

[0041] Preferably, the Na in the mixed slurry + and K + The sum of the concentrations is 0.01~1.0mol / L.

[0042] Further preferably, the Na of the mixed slurry is + and K + The sum of the concentrations is 0.1-0.5 mol / L.

[0043] Preferably, the heating temperature is 120-180°C. The present invention further controls the heating temperature, and can selectively dissolve the more soluble aluminum silicon components in the ore dressing tailings, convert them into effective components of the cementitious material admixture, and retain the less soluble aluminum silicon components in the ore dressing tailings, so that they serve as aggregates of the cementitious material. Through the coordination of heating temperature and insulation time, the insulation time can be appropriately shortened at a higher heating temperature and appropriately extended at a lower heating temperature, so as to improve the production efficiency of the cementitious material admixture and reduce the production cost.

[0044] The components such as Si, Al, Ca, Mg, Na, and K with high activity in the beneficiation tailings need to be dissolved efficiently at a higher reaction temperature, and then the dissolved Si, Al, Ca, Mg, Na, and K components undergo chemical combination and crystallization reactions to form hydrated calcium silicate and / or zeolite products. Increasing the reaction temperature and extending the reaction time can increase the crystallization degree of hydrated calcium silicate and / or zeolite, but it will also increase the comprehensive cost of preparing cementitious material admixtures from beneficiation tailings. Therefore, as a preferred method, the insulation time can be appropriately shortened at a higher reaction temperature to improve production efficiency and reduce costs.

[0045] The method for preparing cementitious material admixture using mineral processing tailings uses lime to stabilize the relatively active components such as Si, Al, Ca, Mg, Na, K in the mineral processing tailings, so as to convert them into hydrated calcium silicate and / or zeolite with certain cementing properties. The reaction product can be used as a cementitious material admixture to prepare filling materials, roadbed materials, building materials and other products.

[0046] Preferably, the liquid product obtained by solid-liquid separation is returned to the batching process as circulating water. + and / or K + The solution can be returned to the batching process for recycling.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] The present invention controls the liquid-to-solid ratio so that the water content in the mixed slurry is higher, thereby achieving better mass transfer effect. At the same time, the heating temperature and insulation time are controlled, which is beneficial to the uniform and full reaction of the active components in the slag or the ore dressing tailings with the lime. While improving the yield, since the active components react completely, the possibility of alkali-aggregate reaction between the active components and the remaining activator during the use stage is minimized, thereby avoiding a significant impact on the strength. At the same time, due to the control of the upper limit of the heating temperature, the inert material in the slag or the ore dressing tailings exists as aggregate, thereby improving the strength of the cementitious material admixture. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1The XRD diagrams of the fly ash used in Examples 1 to 5 of the present invention and Example 3;

[0050] Figure 2 This is a SEM image of the fly ash used in Examples 1 to 5 of the present invention;

[0051] Figure 3 This is a SEM image of the cementitious material admixture prepared in Example 2 of the present invention;

[0052] Figure 4 This is a SEM image of the cementitious material admixture prepared in Example 4 of the present invention;

[0053] Figure 5 This is a SEM image of the cementitious material admixture prepared in Example 6 of the present invention;

[0054] Figure 6 This is a SEM image of the cementitious material admixture prepared in Example 11 of the present invention;

[0055] Figure 7 This is a SEM image of the cementitious material admixture prepared in Comparative Example 1 of the present invention;

[0056] Figure 8 This is a SEM image of the cementitious material admixture prepared in Comparative Example 2 of the present invention;

[0057] Fig. 9 This is a SEM image of the cementitious material admixture prepared in Comparative Example 3 of the present invention;

[0058] Fig.10 XRD diagrams of the fluorite tailings used in Examples 12 to 16 of the present invention and Example 14;

[0059] Fig.11 This is a SEM image of the fluorite tailings used in Examples 12 to 16 of the present invention;

[0060] Fig.12 This is a SEM image of the decomposition and conversion of the more active kaolinite and calcite in the fluorite tailings of the cementitious material prepared in Example 13 of the present invention into a calcium silicate hydrate composite;

[0061] Fig.13 This is a SEM image of the cementitious material admixture prepared in Example 15 of the present invention;

[0062] Fig.14 This is a SEM image of the cementitious material admixture prepared in Example 17 of the present invention;

[0063] Fig.15 This is the SEM image of the cementitious material admixture prepared in Example 23 of the present invention.

[0064] Fig.16This is a SEM image of the cementitious material admixture prepared in Comparative Example 4 of the present invention;

[0065] Fig.17 This is a SEM image of the cementitious material admixture prepared in Comparative Example 5 of the present invention;

[0066] Fig.18 This is a SEM image of the cementitious material admixture prepared in Comparative Example 6 of the present invention. DETAILED DESCRIPTION

[0067] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0068] Example 1

[0069] Step S1: According to the Ca / Si molar ratio of 0.1, the liquid-to-solid ratio of 3 mL / g, and the Na + The concentration is 1.0 mol / L, and fly ash is mixed with lime, sodium carbonate and water to form a mixed slurry with a certain fluidity;

[0070] Step S2: injecting the mixed slurry into a closed container with a stirring device, turning on the stirring and heating switches of the closed container, adjusting the stirring line speed to 300 m / s, and setting the predetermined temperature to 30° C.;

[0071] Step S3: After the mixed slurry is kept at a predetermined temperature of 30° C. for 10 hours, the reaction product in the sealed container is released;

[0072] Step S4: The reaction product is subjected to solid-liquid separation, the solid product is the cementitious material admixture, and the liquid product is the circulating water.

[0073] Detect the Na of the circulating water in step S4 respectively + concentration and the microstructure of cementitious admixtures. The results show that the Na + The concentration is 0.8mol / L. The physical composition of the cementitious admixture is mainly quartz, mullite, and calcium silicate hydrate. From the SEM image of the cementitious admixture, it can be observed that calcium silicate hydrate gel products are attached to the surface of spherical particles. This shows that the amorphous substances in the fly ash are dissolved in the alkaline solution and converted into calcium silicate hydrate. The undissolved quartz and mullite still maintain the spherical structure of the fly ash particles and play a skeletal support role for the calcium silicate hydrate gel. When 10wt.% of the cementitious admixture is used to replace diatomaceous earth in the preparation of calcium silicate board, the flexural strength of the calcium silicate board is increased by 3-5%.

[0074] Example 2

[0075] Step S1: According to the Ca / Si molar ratio of 0.3, the liquid-to-solid ratio of 5 mL / g, and the Na +The concentration is 0.8 mol / L, and fly ash is mixed with lime, sodium sulfate, and water to form a mixed slurry with a certain fluidity;

[0076] Step S2: injecting the mixed slurry into a closed container with a stirring device, turning on the stirring and heating switches of the closed container, adjusting the stirring line speed to 250 m / s, and setting the predetermined temperature to 60° C.;

[0077] Step S3: After the mixed slurry is kept at a predetermined temperature of 60° C. for 8 hours, the reaction product in the sealed container is released;

[0078] Step S4: The reaction product is subjected to solid-liquid separation, the solid product is the cementitious material admixture, and the liquid product is the circulating water.

[0079] Detect the Na of the circulating water in step S4 respectively + concentration and the microstructure of cementitious admixtures. The results show that the Na + The concentration is 0.6mol / L, and the physical composition of the cementitious material admixture is mainly quartz, mullite, and calcium silicate hydrate. From the SEM image of the cementitious material admixture, it can be observed that the calcium silicate hydrate gel product is attached to the surface of the spherical particles, which indicates that the amorphous substances in the fly ash are dissolved in the alkaline solution and converted into calcium silicate hydrate, and the undissolved quartz and mullite still maintain the spherical structure of the fly ash particles and play a skeletal support role for the calcium silicate hydrate gel. When 10wt.% of the cementitious material admixture is used to replace diatomaceous earth in the preparation of calcium silicate board, the flexural strength of the calcium silicate board is increased by 5-10%.

[0080] Example 3

[0081] Step S1: According to the Ca / Si molar ratio of 0.5, the liquid-to-solid ratio of 8 mL / g, and the Na + The concentration is 0.6 mol / L, and fly ash is mixed with lime, sodium silicate and water to prepare a mixed slurry with a certain fluidity;

[0082] Step S2: injecting the mixed slurry into a closed container with a stirring device, turning on the stirring and heating switches of the closed container, adjusting the stirring line speed to 200 m / s, and setting the predetermined temperature to 90° C.;

[0083] Step S3: After the mixed slurry is kept at a predetermined temperature of 90° C. for 6 hours, the reaction product in the sealed container is released;

[0084] Step S4: The reaction product is subjected to solid-liquid separation, the solid product is the cementitious material admixture, and the liquid product is the circulating water.

[0085] Detect the Na of the circulating water in step S4 respectively +concentration and the microstructure of cementitious admixtures. The results show that the Na + The concentration is 0.8mol / L, and the physical composition of the cementitious material admixture is mainly quartz, mullite, and calcium silicate hydrate. From the SEM image of the cementitious material admixture, it can be observed that the calcium silicate hydrate gel product is attached to the surface of the spherical particles, which indicates that the amorphous substances in the fly ash are dissolved in the alkaline solution and converted into calcium silicate hydrate, and the undissolved quartz and mullite still maintain the spherical structure of the fly ash particles and play a skeletal support role for the calcium silicate hydrate gel. When 10wt.% of the cementitious material admixture is used to replace diatomaceous earth in the preparation of calcium silicate board, the flexural strength of the calcium silicate board is increased by 10-20%.

[0086] Example 4

[0087] Step S1: According to the Ca / Si molar ratio of 0.7, the liquid-to-solid ratio of 12 mL / g, and the Na + The concentration is 0.4 mol / L, and fly ash is mixed with lime, sodium hydroxide and water to prepare a mixed slurry with a certain fluidity;

[0088] Step S2: injecting the mixed slurry into a closed container with a stirring device, turning on the stirring and heating switches of the closed container, adjusting the stirring linear speed to 150 m / s, and setting the predetermined temperature to 120° C.;

[0089] Step S3: After the mixed slurry is kept at a predetermined temperature of 120° C. for 3 hours, the reaction product in the sealed container is released;

[0090] Step S4: The reaction product is subjected to solid-liquid separation, the solid product is the cementitious material admixture, and the liquid product is the circulating water.

[0091] Detect the Na of the circulating water in step S4 respectively + concentration and the microstructure of cementitious admixtures. The results show that the Na + The concentration is 0.8 mol / L, and the physical composition of the cementitious material admixture is mainly quartz, mullite, calcium silicate hydrate, and hydroxylite; from the SEM image of the cementitious material admixture, it can be observed that the calcium silicate hydrate gel product is attached to the surface of the spherical particles; it means that the amorphous matter in the fly ash is dissolved in the alkaline solution and converted into calcium silicate hydrate, and the undissolved quartz and mullite still maintain the spherical structure of the fly ash particles and play a skeletal support role for the calcium silicate hydrate gel; due to the high Ca / Si molar ratio in step S1, the XRD diffraction peak of hydroxylite is detected in the obtained cementitious material admixture. When 10wt.% of the cementitious material admixture is used to replace diatomaceous earth in the preparation of calcium silicate board, the flexural strength of the calcium silicate board is increased by 15-30%.

[0092] Example 5

[0093] Step S1: According to the Ca / Si molar ratio of 0.9, the liquid-to-solid ratio of 15 mL / g, and the K + The concentration is 0.1 mol / L, and fly ash is mixed with lime, potassium carbonate and water to form a mixed slurry with a certain fluidity;

[0094] Step S2: injecting the mixed slurry into a closed container with a stirring device, turning on the stirring and heating switches of the closed container, adjusting the stirring linear speed to 100 m / s, and setting the predetermined temperature to 95° C.;

[0095] Step S3: After the mixed slurry is kept at a predetermined temperature of 95° C. for 1 hour, the reaction product in the sealed container is released;

[0096] Step S4: The reaction product is subjected to solid-liquid separation, the solid product is the cementitious material admixture, and the liquid product is the circulating water.

[0097] Detect the K of the circulating water in step S4 respectively + concentration and the microstructure of the cementitious admixture. The results show that the K + The concentration is 0.06mol / L, and the physical composition of the cementitious material admixture is mainly quartz, mullite, calcium silicate hydrate, and hydroxylite; from the SEM image of the cementitious material admixture, it can be observed that the calcium silicate hydrate gel product is attached to the surface of the spherical particles; it means that the amorphous matter in the fly ash is dissolved in the alkaline solution and converted into calcium silicate hydrate, and the undissolved quartz and mullite still maintain the spherical structure of the fly ash particles and play a skeletal support role for the calcium silicate hydrate gel; due to the high Ca / Si molar ratio in step S1, the XRD diffraction peak of hydroxylite is detected in the obtained cementitious material admixture. When 10wt.% of the cementitious material admixture is used to replace diatomaceous earth in the preparation of calcium silicate board, the flexural strength of the calcium silicate board is increased by 20-30%.

[0098] Example 6

[0099] Step S1: According to the Ca / Si molar ratio of 1.0, the liquid-to-solid ratio of 10 mL / g, and the K + The concentration is 0.01 mol / L, coal chemical gasification slag is mixed with lime, potassium sulfate and water to make a mixed slurry with a certain fluidity;

[0100] Step S2: injecting the mixed slurry into a closed container with a stirring device, turning on the stirring and heating switches of the closed container, adjusting the stirring linear speed to 150 m / s, and setting the predetermined temperature to 120° C.;

[0101] Step S3: After the mixed slurry is kept at a predetermined temperature of 120° C. for 0.1 h, the reaction product in the sealed container is released;

[0102] Step S4: The reaction product is subjected to solid-liquid separation, the solid product is the cementitious material admixture, and the liquid product is the circulating water.

[0103] Detect the K of the circulating water in step S4 respectively + concentration and the microstructure of the cementitious admixture. The results show that the K + The concentration is 0.005 mol / L, and the physical composition of the cementitious admixture is mainly quartz, calcium silicate hydrate, and hydroxylite; from the SEM image of the cementitious admixture, it can be observed that calcium silicate hydrate gel is generated; it means that the amorphous material in the coal chemical gasification slag is dissolved in the alkaline solution and converted into calcium silicate hydrate, and the undissolved quartz plays a skeleton support role for the calcium silicate hydrate gel; due to the high Ca / Si molar ratio of step S1, the XRD diffraction peak of hydroxylite is detected in the obtained cementitious admixture. When 10wt.% of the cementitious admixture is used to replace clay in the preparation of concrete base, the compressive strength of the concrete base is increased by 8-12%.

[0104] Example 7

[0105] Step S1: According to the Ca / Si molar ratio of 0.6, the liquid-to-solid ratio of 8 mL / g, and the K + The concentration is 0.3 mol / L, coal chemical gasification slag is mixed with lime, potassium hydroxide and water to prepare a mixed slurry with a certain fluidity;

[0106] Step S2: injecting the mixed slurry into a closed container with a stirring device, turning on the stirring and heating switches of the closed container, adjusting the stirring line speed to 180 m / s, and setting the predetermined temperature to 90° C.;

[0107] Step S3: After the mixed slurry is kept at a predetermined temperature of 90° C. for 0.5 h, the reaction product in the sealed container is released;

[0108] Step S4: The reaction product is subjected to solid-liquid separation, the solid product is the cementitious material admixture, and the liquid product is the circulating water.

[0109] Detect the K of the circulating water in step S4 respectively + concentration and the microstructure of the cementitious admixture. The results show that the K +The concentration is 0.15mol / L, and the phase composition of the cementitious material admixture is mainly quartz, calcium silicate hydrate, and pyroxene. From the SEM image of the cementitious material admixture, it can be observed that calcium silicate hydrate gel is generated, which indicates that the amorphous substances in the coal chemical gasification slag are dissolved in the alkaline solution and converted into calcium silicate hydrate, and the undissolved quartz and pyroxene play a skeletal support role for the calcium silicate hydrate gel. When 10wt.% of the cementitious material admixture is used to replace clay in the preparation of concrete base, the compressive strength of the concrete base is increased by 5-15%.

[0110] Example 8

[0111] Step S1: According to the Ca / Si molar ratio of 0.2, the liquid-to-solid ratio of 6 mL / g, and the Na + The concentration is 1 mol / L, coal chemical gasification slag is mixed with lime, sodium hydroxide and water to prepare a mixed slurry with a certain fluidity;

[0112] Step S2: injecting the mixed slurry into a closed container with a stirring device, turning on the stirring and heating switches of the closed container, adjusting the stirring line speed to 200 m / s, and setting the predetermined temperature to 80° C.;

[0113] Step S3: After the mixed slurry is kept at a predetermined temperature of 80° C. for 2 hours, the reaction product in the sealed container is released;

[0114] Step S4: The reaction product is subjected to solid-liquid separation, the solid product is the cementitious material admixture, and the liquid product is the circulating water.

[0115] Detect the Na of the circulating water in step S4 respectively + concentration and the microstructure of cementitious admixtures. The results show that the Na + The concentration is 0.75mol / L, and the physical composition of the cementitious material admixture is mainly quartz and calcium silicate hydrate. From the SEM image of the cementitious material admixture, it can be observed that calcium silicate hydrate gel is generated, which indicates that the amorphous substances in the coal chemical gasification slag are dissolved in the alkaline solution and converted into calcium silicate hydrate, and the undissolved quartz plays a skeletal support role for the calcium silicate hydrate gel. When 10wt.% of the cementitious material admixture is used to replace clay in the preparation of concrete base, the compressive strength of the concrete base is increased by 10-20%.

[0116] Example 9

[0117] Step S1: According to the Ca / Si molar ratio of 0.6, the liquid-to-solid ratio of 4 mL / g, and the Na + The concentration is 0.5 mol / L, and the gold smelting slag is mixed with lime, sodium silicate and water to prepare a mixed slurry with a certain fluidity;

[0118] Step S2: injecting the mixed slurry into a closed container with a stirring device, turning on the stirring and heating switches of the closed container, adjusting the stirring line speed to 200 m / s, and setting the predetermined temperature to 80° C.;

[0119] Step S3: After the mixed slurry is kept at a predetermined temperature of 80° C. for 5 hours, the reaction product in the sealed container is released;

[0120] Step S4: The reaction product is subjected to solid-liquid separation, the solid product is the cementitious material admixture, and the liquid product is the circulating water.

[0121] Detect the Na of the circulating water in step S4 respectively + concentration and the microstructure of cementitious admixtures. The results show that the Na + The concentration is 0.35mol / L, and the phase composition of the cementitious material admixture is mainly magnetite, calcite, hydrated garnet, and hydrated calcium silicate; from the SEM image of the cementitious material admixture, it can be observed that hydrated calcium silicate gel is generated; this indicates that the amorphous material in the gold smelting slag is dissolved in the alkaline solution and converted into hydrated calcium silicate and hydrated garnet, and the undissolved magnetite and calcite play a skeletal support role for the hydrated calcium silicate gel. When 10wt.% of the cementitious material admixture is used to replace the slag powder in the preparation of unfired bricks, the compressive strength of the unfired bricks is increased by 15-20%.

[0122] Example 10

[0123] Step S1: According to the Ca / Si molar ratio of 0.8, the liquid-to-solid ratio of 10 mL / g, and the Na + The concentration is 0.8 mol / L, and blast furnace slag is mixed with lime, sodium carbonate and water to form a mixed slurry with a certain fluidity;

[0124] Step S2: injecting the mixed slurry into a closed container with a stirring device, turning on the stirring and heating switches of the closed container, adjusting the stirring line speed to 150 m / s, and setting the predetermined temperature to 100° C.;

[0125] Step S3: After the mixed slurry is kept at a predetermined temperature of 100° C. for 3 hours, the reaction product in the sealed container is released;

[0126] Step S4: The reaction product is subjected to solid-liquid separation, the solid product is the cementitious material admixture, and the liquid product is the circulating water.

[0127] Detect the Na of the circulating water in step S4 respectively + concentration and the microstructure of cementitious admixtures. The results show that the Na +The concentration is 0.75mol / L. The phase composition of the cementitious admixture is mainly calcium silicate hydrate. From the SEM image of the cementitious admixture, calcium silicate hydrate fibers can be observed, indicating that blast furnace slag can be fully dissolved in alkaline solution and converted into calcium silicate hydrate. When 10wt.% of cementitious admixture is used to replace slag powder in the preparation of unfired bricks, the compressive strength of the unfired bricks is increased by 18-30%.

[0128] Embodiment 11

[0129] Step S1: According to the Ca / Si molar ratio of 0.3, the liquid-to-solid ratio of 8 mL / g, and the Na + The concentration is 0.25 mol / L, and the copper smelting slag is mixed with lime, sodium hydroxide and water to prepare a mixed slurry with a certain fluidity;

[0130] Step S2: injecting the mixed slurry into a closed container with a stirring device, turning on the stirring and heating switches of the closed container, adjusting the stirring linear speed to 180 m / s, and setting the predetermined temperature to 80° C.;

[0131] Step S3: After the mixed slurry is kept at a predetermined temperature of 80° C. for 2 hours, the reaction product in the sealed container is released;

[0132] Step S4: The reaction product is subjected to solid-liquid separation, the solid product is the cementitious material admixture, and the liquid product is the circulating water.

[0133] Detect the Na of the circulating water in step S4 respectively + concentration and the microstructure of cementitious admixtures. The results show that the Na + The concentration is 0.15mol / L. The phase composition of the cementitious material admixture is mainly fayalite and hydrated calcium silicate. From the SEM image of the cementitious material admixture, it can be observed that hydrated calcium silicate gel is generated; this indicates that the amorphous material in the copper smelting slag is dissolved in the alkaline solution and converted into hydrated calcium silicate. The undissolved fayalite plays a skeletal support role for the hydrated calcium silicate gel. When 10wt.% of the cementitious material admixture is used to replace the slag powder in the preparation of unfired bricks, the compressive strength of the unfired bricks is increased by 8-15%.

[0134] Comparative Example 1

[0135] Compared with Example 2, the liquid-to-solid ratio is 2 mL / g. The phase composition of the obtained reaction product is mainly quartz, mullite, and calcium silicate hydrate; from the SEM image of the cementitious material admixture, a small amount of calcium silicate hydrate gel product and spherical fly ash particles that did not participate in the reaction can be observed; indicating that the reaction is not sufficient and there are more local reactions. When 10wt.% of the reaction product is used to replace diatomaceous earth in the preparation of calcium silicate board, the flexural strength of the calcium silicate board is reduced by 6-15%.

[0136] Comparative Example 2

[0137] Compared with Example 6, the heating temperature is 20°C. The phase composition of the obtained reaction product is mainly quartz and calcium silicate hydrate; no calcium silicate hydrate gel can be observed from the SEM image of the cementitious material admixture; it is difficult for coal chemical gasification slag to dissolve and generate calcium silicate hydrate at a lower reaction temperature and a shorter reaction time. When 10wt.% of the cementitious material admixture is used to replace clay in the preparation of concrete base, the compressive strength of the concrete base is reduced by 5-10%.

[0138] Comparative Example 3

[0139] Compared with Example 11, the heating temperature is 180°C. The phase composition of the obtained cementitious material admixture is mainly fayalite and calcium silicate hydrate. From the SEM image of the cementitious material admixture, it can be observed that fibrous calcium silicate hydrate is generated, indicating that copper smelting slag can be fully dissolved in alkaline solution and converted into calcium silicate hydrate with high crystallinity. When 10wt.% of cementitious material admixture is used to replace slag powder in equal amounts for preparing unfired bricks, the compressive strength of the unfired bricks is reduced by 3-5%.

[0140] from Figure 1 , Figure 2 It can be seen that the main phases of fly ash are amorphous substances, quartz and mullite, etc., and its SEM morphology is glassy spherical particles of varying sizes. After being kept at a predetermined temperature for a period of time, the more active amorphous substances in the fly ash decompose and transform into hydrated calcium silicate, and part of the unreacted active calcium transforms into hydroxy calcium silicate ( Figure 1 );

[0141] from Figure 3 , Figure 4 It can be seen that the calcium silicate hydrate generated by the reaction is mainly attached to the surface of the spherical particles of fly ash. This is because the dissolution of amorphous matter and the formation of calcium silicate hydrate are carried out simultaneously, and the undissolved quartz and mullite act as the skeleton of the calcium silicate hydrate product, so that the prepared cementitious material admixture maintains a high activity, which is beneficial to improve the strength of the cementitious material.

[0142] from Figure 5 , Figure 6 It can be seen that coal chemical gasification slag and copper smelting slag can also be used to prepare cementitious material admixtures. The microstructure of the reaction product is similar to Figure 3 , Figure 4 Consistent with the above, calcium silicate hydrate has a low degree of crystallization and is gel-like.

[0143] from Figure 7It can be seen that at a too low liquid-to-solid ratio, the mixed slurry is relatively viscous (semi-dry state), which will lead to poor energy and material transfer in the reaction process and more local reactions. Therefore, there are still many spherical fly ash particles that do not participate in the reaction in the reaction products.

[0144] from Figure 8 It can be seen that the chemical reaction rate is lower at a lower temperature, and the active components of the coal chemical gasification slag are almost insoluble in a shorter insulation time, and still maintain their granular form.

[0145] from Fig. 9 It can be seen that at a higher reaction temperature, copper smelting slag fully dissolves in alkaline solution and reacts with lime to produce well-crystallized, fibrous calcium silicate hydrate. Crystalline calcium silicate hydrate has low activity and low apparent density, and its effect on improving material strength is not significant, and may even reduce material strength.

[0146] Example 12

[0147] Step S1: According to the Ca / Si molar ratio of 0.05, the liquid-to-solid ratio of 3 mL / g, and the Na + The concentration is 1.0 mol / L, and the fluorite tailings are mixed with lime, sodium carbonate and water to make a mixed slurry with a certain fluidity;

[0148] Step S2: injecting the mixed slurry into a closed container with a stirring device, turning on the stirring and heating switches of the closed container, adjusting the stirring line speed to 300 m / s, and setting the predetermined temperature to 90° C.;

[0149] Step S3: After the mixed slurry is kept at a predetermined temperature of 90° C. for 10 hours, the reaction product in the sealed container is released;

[0150] Step S4: The reaction product is subjected to solid-liquid separation, the solid product is the cementitious material admixture, and the liquid product is the circulating water.

[0151] Detect the Na of the circulating water in step S4 respectively + concentration and the microstructure of cementitious admixtures. The results show that the Na +The concentration is 0.8 mol / L, and the phase composition of the cementitious material admixture is mainly quartz, calcite, and mica; due to the low Ca / Si molar ratio in step S1, no XRD diffraction peaks of hydrated calcium silicate or zeolite are detected in the obtained cementitious material admixture, but from the SEM image of the cementitious material admixture, it can be observed that hydrated calcium silicate gel products are attached to the surface of quartz particles; this indicates that kaolinite in the fluorite tailings is dissolved in the alkaline solution and converted into hydrated calcium silicate, and the undissolved quartz, calcite, and mica play a skeletal support role for the hydrated calcium silicate gel. When quartz powder is replaced by an equal amount of 10wt.% cementitious material admixture for the preparation of calcium silicate board, the flexural strength of the calcium silicate board is increased by 3-8%.

[0152] Embodiment 13

[0153] Step S1: According to the Ca / Si molar ratio of 0.1, the liquid-to-solid ratio of 5 mL / g, and the Na + The concentration is 0.8 mol / L, and the fluorite tailings are mixed with lime, sodium sulfate and water to make a mixed slurry with a certain fluidity;

[0154] Step S2: injecting the mixed slurry into a closed container with a stirring device, turning on the stirring and heating switches of the closed container, adjusting the stirring line speed to 250 m / s, and setting the predetermined temperature to 120° C.;

[0155] Step S3: After the mixed slurry is kept at a predetermined temperature of 120° C. for 8 hours, it is cooled to reduce the pressure of the sealed container to below 0.1 MPa, and the reaction product in the sealed container is released;

[0156] Step S4: The reaction product is subjected to solid-liquid separation, the solid product is the cementitious material admixture, and the liquid product is the circulating water.

[0157] Detect the Na of the circulating water in step S4 respectively + concentration and the microstructure of cementitious admixtures. The results show that the Na + The concentration is 0.6 mol / L, and the physical composition of the cementitious material admixture is mainly quartz, calcite, and mica; due to the low Ca / Si molar ratio in step S1, no XRD diffraction peaks of hydrated calcium silicate or zeolite are detected in the obtained cementitious material admixture, but from the SEM image of the cementitious material admixture, it can be observed that hydrated calcium silicate gel products are attached to the surface of quartz particles; this indicates that kaolinite in the fluorite tailings is dissolved in the alkaline solution and converted into hydrated calcium silicate, and the undissolved quartz, calcite, and mica play a skeletal support role for the hydrated calcium silicate gel. When quartz powder is replaced by an equal amount of 10wt.% cementitious material admixture for the preparation of calcium silicate board, the flexural strength of the calcium silicate board is increased by 5-12%.

[0158] Embodiment 14

[0159] Step S1: According to the Ca / Si molar ratio of 0.2, the liquid-to-solid ratio of 8 mL / g, and the Na + The concentration is 0.6 mol / L, and the fluorite tailings are mixed with lime, sodium silicate and water to make a mixed slurry with a certain fluidity;

[0160] Step S2: injecting the mixed slurry into a closed container with a stirring device, turning on the stirring and heating switches of the closed container, adjusting the stirring line speed to 200 m / s, and setting the predetermined temperature to 150° C.;

[0161] Step S3: After the mixed slurry is kept at a predetermined temperature of 150° C. for 6 hours, it is cooled to reduce the pressure of the sealed container to below 0.1 MPa, and the reaction product in the sealed container is released;

[0162] Step S4: The reaction product is subjected to solid-liquid separation, the solid product is the cementitious material admixture, and the liquid product is the circulating water.

[0163] Detect the Na of the circulating water in step S4 respectively + concentration and the microstructure of cementitious admixtures. The results show that the Na + The concentration is 0.8 mol / L, and the physical composition of the cementitious material admixture is mainly quartz, calcite, mica, and calcium silicate hydrate; due to the low Ca / Si molar ratio in step S1, the XRD diffraction peak intensity of calcium silicate hydrate in the obtained cementitious material admixture is low, and the formation of calcium silicate hydrate gel product can be observed from the SEM image of the cementitious material admixture; it indicates that the kaolinite in the fluorite tailings is dissolved in the alkaline solution and converted into calcium silicate hydrate, and the undissolved quartz, calcite, and mica play a skeleton supporting role for the calcium silicate hydrate gel. When quartz powder is replaced by 10wt.% of the cementitious material admixture in the preparation of calcium silicate board, the flexural strength of the calcium silicate board is increased by 15-30%.

[0164] Embodiment 15

[0165] Step S1: According to the Ca / Si molar ratio of 0.4, the liquid-to-solid ratio of 12 mL / g, and the Na + The concentration is 0.4 mol / L, and the fluorite tailings are mixed with lime, sodium hydroxide and water to make a mixed slurry with a certain fluidity;

[0166] Step S2: injecting the mixed slurry into a closed container with a stirring device, turning on the stirring and heating switches of the closed container, adjusting the stirring linear speed to 150 m / s, and setting the predetermined temperature to 180° C.;

[0167] Step S3: After the mixed slurry is kept at a predetermined temperature of 180° C. for 3 hours, it is cooled to reduce the pressure of the sealed container to below 0.1 MPa, and the reaction product in the sealed container is released;

[0168] Step S4: The reaction product is subjected to solid-liquid separation, the solid product is the cementitious material admixture, and the liquid product is the circulating water.

[0169] Detect the Na of the circulating water in step S4 respectively + concentration and the microstructure of cementitious admixtures. The results show that the Na + The concentration is 0.8mol / L. The phase composition of the cementitious material admixture is mainly quartz, calcite, mica, and calcium silicate hydrate. The XRD diffraction peak intensity of calcium silicate hydrate is relatively high. From the SEM image of the cementitious material admixture, it can be observed that fibrous calcium silicate hydrate is generated; this indicates that the kaolinite in the fluorite tailings is dissolved in the alkaline solution and converted into calcium silicate hydrate. The undissolved quartz, calcite, and mica play a skeletal supporting role for the calcium silicate hydrate gel. When quartz powder is replaced by 10wt.% of the cementitious material admixture in the same amount for the preparation of calcium silicate board, the flexural strength of the calcium silicate board is increased by 20-35%.

[0170] Example 16

[0171] Step S1: According to the Ca / Si molar ratio of 0.6, the liquid-to-solid ratio of 15 mL / g, and the K + The concentration is 0.1 mol / L, and the fluorite tailings are mixed with lime, potassium carbonate and water to make a mixed slurry with a certain fluidity;

[0172] Step S2: injecting the mixed slurry into a closed container with a stirring device, turning on the stirring and heating switches of the closed container, adjusting the stirring linear speed to 100 m / s, and setting the predetermined temperature to 200° C.;

[0173] Step S3: After the mixed slurry is kept at a predetermined temperature of 200° C. for 1 hour, it is cooled to reduce the pressure of the sealed container to below 0.1 MPa, and the reaction product in the sealed container is released;

[0174] Step S4: The reaction product is subjected to solid-liquid separation, the solid product is the cementitious material admixture, and the liquid product is the circulating water.

[0175] Detect the K of the circulating water in step S4 respectively + concentration and the microstructure of the cementitious admixture. The results show that the K +The concentration is 0.06 mol / L. The physical composition of the cementitious admixture is mainly quartz, calcite, mica, calcium silicate hydrate and hydroxylite. The XRD diffraction peak intensity of calcium silicate hydrate is relatively high. From the SEM image of the cementitious admixture, it can be observed that fibrous calcium silicate hydrate is generated; this indicates that the kaolinite in the fluorite tailings is dissolved in the alkaline solution and converted into calcium silicate hydrate, and the undissolved quartz, calcite and mica play a skeletal supporting role for the calcium silicate hydrate gel; due to the high Ca / Si molar ratio in step S1, hydroxylite (Ca(OH) 2 ) XRD diffraction peak. When quartz powder is replaced by 10wt.% of cementitious material admixture in the same amount for preparing calcium silicate board, the flexural strength of the calcium silicate board is increased by 15-20%.

[0176] Embodiment 17

[0177] Step S1: According to the Ca / Si molar ratio of 0.5, the liquid-to-solid ratio of 10 mL / g, and the K + The concentration is 0.01 mol / L, and the bauxite tailings are mixed with lime, potassium sulfate, and water to form a mixed slurry with a certain fluidity;

[0178] Step S2: injecting the mixed slurry into a closed container with a stirring device, turning on the stirring and heating switches of the closed container, adjusting the stirring linear speed to 150 m / s, and setting the predetermined temperature to 180° C.;

[0179] Step S3: After the mixed slurry is kept at a predetermined temperature of 180° C. for 0.1 h, it is cooled to reduce the pressure of the sealed container to below 0.1 MPa, and the reaction product in the sealed container is released;

[0180] Step S4: The reaction product is subjected to solid-liquid separation, the solid product is the cementitious material admixture, and the liquid product is the circulating water.

[0181] Detect the K of the circulating water in step S4 respectively + concentration and the microstructure of the cementitious admixture. The results show that the K +The concentration is 0.005 mol / L, and the physical composition of the cementitious material admixture is mainly quartz, diaspore, pyrophyllite, illite, and kaolinite. Due to the short insulation time of step S3, no XRD diffraction peaks of hydrated calcium silicate or zeolite are detected in the obtained cementitious material admixture, but it can be observed from the SEM image of the cementitious material admixture that hydrated calcium silicate gel is generated; it shows that some active components in the bauxite tailings are dissolved in the alkaline solution and converted into hydrated calcium silicate, and the undissolved quartz, diaspore, pyrophyllite, illite, and kaolinite play a skeleton support role for the hydrated calcium silicate gel. 10wt.% of the cementitious material admixture is used to replace quartz powder in the preparation of calcium silicate board, and the flexural strength of the calcium silicate board is increased by 8-15%.

[0182] Embodiment 18

[0183] Step S1: According to the Ca / Si molar ratio of 0.3, the liquid-to-solid ratio of 8 mL / g, and the K + The concentration is 0.3 mol / L, and the bauxite tailings are mixed with lime, potassium hydroxide, and water to prepare a mixed slurry with a certain fluidity;

[0184] Step S2: injecting the mixed slurry into a closed container with a stirring device, turning on the stirring and heating switches of the closed container, adjusting the stirring line speed to 180 m / s, and setting the predetermined temperature to 150° C.;

[0185] Step S3: After the mixed slurry is kept at a predetermined temperature of 150° C. for 0.5 h, it is cooled to reduce the pressure of the sealed container to below 0.1 MPa, and the reaction product in the sealed container is released;

[0186] Step S4: The reaction product is subjected to solid-liquid separation, the solid product is the cementitious material admixture, and the liquid product is the circulating water.

[0187] Detect the K of the circulating water in step S4 respectively + concentration and the microstructure of the cementitious admixture. The results show that the K + The concentration is 0.15mol / L. The phase composition of the cementitious material admixture is mainly quartz, diaspore, pyrophyllite, illite, and calcium silicate hydrate. The XRD diffraction peak intensity of calcium silicate hydrate is weak. From the SEM image of the cementitious material admixture, it can be observed that calcium silicate hydrate gel is generated; it means that kaolinite in the bauxite tailings is dissolved in the alkaline solution and converted into calcium silicate hydrate. The undissolved quartz, diaspore, pyrophyllite, and illite play a skeletal support role for the calcium silicate hydrate gel. When quartz powder is replaced by 10wt.% of the cementitious material admixture in the same amount for the preparation of calcium silicate board, the flexural strength of the calcium silicate board is increased by 15-20%.

[0188] Embodiment 19

[0189] Step S1: According to the Ca / Si molar ratio of 0.5, the liquid-to-solid ratio of 6 mL / g, and the Na + The concentration is 1 mol / L, and the bauxite tailings are mixed with lime, sodium hydroxide and water to prepare a mixed slurry with a certain fluidity;

[0190] Step S2: injecting the mixed slurry into a closed container with a stirring device, turning on the stirring and heating switches of the closed container, adjusting the stirring line speed to 200 m / s, and setting the predetermined temperature to 150° C.;

[0191] Step S3: After the mixed slurry is kept at a predetermined temperature of 150° C. for 2 hours, it is cooled to reduce the pressure of the sealed container to below 0.1 MPa, and the reaction product in the sealed container is released;

[0192] Step S4: The reaction product is subjected to solid-liquid separation, the solid product is the cementitious material admixture, and the liquid product is the circulating water.

[0193] Detect the Na of the circulating water in step S4 respectively + concentration and the microstructure of cementitious admixtures. The results show that the Na + The concentration is 0.75mol / L. The physical composition of the cementitious material admixture is mainly quartz, diaspore, pyrophyllite, illite, calcium silicate hydrate and hydrated garnet (zeolite). From the SEM picture of the cementitious material admixture, it can be observed that calcium silicate hydrate gel and hydrated garnet are generated; it means that kaolinite in the bauxite tailings is dissolved in the alkaline solution and converted into calcium silicate hydrate and hydrated garnet, and the undissolved quartz, diaspore, pyrophyllite and illite play a skeleton supporting role for the calcium silicate hydrate gel. When quartz powder is replaced by 10wt.% of the cementitious material admixture in the same amount for the preparation of calcium silicate board, the flexural strength of the calcium silicate board is increased by 15-30%.

[0194] Embodiment 20

[0195] Step S1: According to the Ca / Si molar ratio of 0.1, the liquid-to-solid ratio of 4 mL / g, and the Na + The concentration is 0.5 mol / L, and the copper-gold tailings are mixed with lime, sodium silicate, and water to form a mixed slurry with a certain fluidity;

[0196] Step S2: injecting the mixed slurry into a closed container with a stirring device, turning on the stirring and heating switches of the closed container, adjusting the stirring line speed to 200 m / s, and setting the predetermined temperature to 180° C.;

[0197] Step S3: After the mixed slurry is kept at a predetermined temperature of 180° C. for 5 hours, it is cooled to reduce the pressure of the sealed container to below 0.1 MPa, and the reaction product in the sealed container is released;

[0198] Step S4: The reaction product is subjected to solid-liquid separation, the solid product is the cementitious material admixture, and the liquid product is the circulating water.

[0199] Detect the Na of the circulating water in step S4 respectively + concentration and the microstructure of cementitious admixtures. The results show that the Na + The concentration is 0.35mol / L. The physical composition of the cementitious material admixture is mainly mica, black mandrel, hydrated calcium silicate and sodalite (zeolite). From the SEM image of the cementitious material admixture, it can be observed that hydrated calcium silicate fiber and sodalite are generated; it shows that the active components in the copper-gold tailings are dissolved in the alkaline solution and converted into hydrated calcium silicate and sodalite, and the undissolved mica and black mandrel play a skeletal support role for the hydrated calcium silicate gel. 10wt.% cementitious material admixture is used to replace slag powder in equal amounts for the preparation of unfired bricks, and the compressive strength of the unfired bricks is increased by 8-20%.

[0200] Embodiment 21

[0201] Step S1: According to the Ca / Si molar ratio of 0.4, the liquid-to-solid ratio of 10 mL / g, and the Na + The concentration is 0.8 mol / L, and the iron ore tailings are mixed with lime, sodium carbonate and water to form a mixed slurry with a certain fluidity;

[0202] Step S2: injecting the mixed slurry into a closed container with a stirring device, turning on the stirring and heating switches of the closed container, adjusting the stirring linear speed to 150 m / s, and setting the predetermined temperature to 160° C.;

[0203] Step S3: After the mixed slurry is kept at a predetermined temperature of 160° C. for 3 hours, it is cooled to reduce the pressure of the sealed container to below 0.1 MPa, and the reaction product in the sealed container is released;

[0204] Step S4: The reaction product is subjected to solid-liquid separation, the solid product is the cementitious material admixture, and the liquid product is the circulating water.

[0205] Detect the Na of the circulating water in step S4 respectively + concentration and the microstructure of cementitious admixtures. The results show that the Na +The concentration is 0.75mol / L. The physical composition of the cementitious material admixture is mainly mica, calcium iron pyroxene, and calcium silicate hydrate. From the SEM image of the cementitious material admixture, it can be observed that calcium silicate hydrate fibers are generated; this indicates that the active components in the iron ore tailings are dissolved in the alkaline solution and converted into calcium silicate hydrate, and the undissolved mica and calcium iron pyroxene play a skeletal support role for the calcium silicate hydrate gel. When 10wt.% of the cementitious material admixture is used to replace the slag powder in the preparation of unfired bricks, the compressive strength of the unfired bricks is increased by 10-25%.

[0206] Embodiment 22

[0207] Step S1: According to the Ca / Si molar ratio of 0.3, the liquid-to-solid ratio of 8 mL / g, and the Na + The concentration is 0.25mol / L, and the lead-zinc ore tailings are mixed with lime, sodium hydroxide and water to prepare a mixed slurry with a certain fluidity;

[0208] Step S2: injecting the mixed slurry into a closed container with a stirring device, turning on the stirring and heating switches of the closed container, adjusting the stirring linear speed to 180 m / s, and setting the predetermined temperature to 180° C.;

[0209] Step S3: After the mixed slurry is kept at a predetermined temperature of 180° C. for 2 hours, it is cooled to reduce the pressure of the sealed container to below 0.1 MPa, and the reaction product in the sealed container is released;

[0210] Step S4: The reaction product is subjected to solid-liquid separation, the solid product is the cementitious material admixture, and the liquid product is the circulating water.

[0211] Detect the Na of the circulating water in step S4 respectively + concentration and the microstructure of cementitious admixtures. The results show that the Na + The concentration is 0.15mol / L. The physical composition of the cementitious material admixture is mainly talc, vermiculite, mica, and calcium silicate hydrate. From the SEM image of the cementitious material admixture, it can be observed that calcium silicate hydrate fibers are generated; this indicates that the active components in the lead-zinc ore tailings are dissolved in the alkaline solution and converted into calcium silicate hydrate, and the undissolved talc, vermiculite, and mica play a skeletal support role for the calcium silicate hydrate gel. When 10wt.% of the cementitious material admixture is used to replace the slag powder in the preparation of unfired bricks, the compressive strength of the unfired bricks is increased by 8-15%.

[0212] Embodiment 23

[0213] Step S1: According to the Ca / Si molar ratio of 0.6, the liquid-to-solid ratio of 12 mL / g, and the Na +The concentration is 0.75 mol / L, and the coal mine tailings are mixed with lime, sodium hydroxide and water to form a mixed slurry with a certain fluidity;

[0214] Step S2: injecting the mixed slurry into a closed container with a stirring device, turning on the stirring and heating switches of the closed container, adjusting the stirring line speed to 180 m / s, and setting the predetermined temperature to 160° C.;

[0215] Step S3: After the mixed slurry is kept at a predetermined temperature of 160° C. for 5 hours, it is cooled to reduce the pressure of the sealed container to below 0.1 MPa, and the reaction product in the sealed container is released;

[0216] Step S4: The reaction product is subjected to solid-liquid separation, the solid product is the cementitious material admixture, and the liquid product is the circulating water.

[0217] Detect the Na of the circulating water in step S4 respectively + concentration and the microstructure of cementitious admixtures. The results show that the Na + The concentration is 0.35mol / L. The phase composition of the cementitious admixture is mainly calcium silicate hydrate and sodalite. From the SEM image of the cementitious admixture, it can be observed that calcium silicate hydrate fibers and sodalite are generated, indicating that the active components in the coal tailings are fully dissolved in the alkaline solution and converted into calcium silicate hydrate and sodalite. When 10wt.% of the cementitious admixture is used to replace the slag powder in the preparation of unfired bricks, the compressive strength of the unfired bricks is increased by 12-30%.

[0218] Comparative Example 4

[0219] Compared with Example 13, the liquid-to-solid ratio is 2 mL / g. The phase composition of the obtained cementitious material admixture is mainly quartz, calcite, and mica; from the SEM image of the reaction product, it can be observed that hydrated calcium silicate gel is generated and no hydrated calcium silicate gel is attached to the surface of the unreacted quartz particles, indicating that under the condition of a lower liquid-to-solid ratio, the reaction is not sufficient and there may be local reactions. When quartz powder is replaced by 10wt.% of the cementitious material admixture in an equal amount for the preparation of calcium silicate board, the flexural strength of the calcium silicate board is increased by 2-5%.

[0220] Comparative Example 5

[0221] Compared with Example 15, the heating temperature is 60°C. The phase composition of the obtained cementitious material admixture is mainly quartz, calcite, mica, and kaolinite. No hydrated calcium silicate can be observed from the SEM image of the reaction product, indicating that the quartz, calcite, kaolinite and other components in the fluorite tailings are almost insoluble at a lower reaction temperature. When quartz powder is replaced by 10wt.% of the cementitious material admixture in the same amount for preparing calcium silicate board, the flexural strength of the calcium silicate board is reduced by 3-8%.

[0222] Comparative Example 6

[0223] Compared with Example 23, the heating temperature is 220°C. The phase composition of the obtained reaction product is mainly calcium silicate hydrate and sodalite. From the SEM image of the cementitious material admixture, it can be observed that fibrous calcium silicate hydrate and spherical zeolite (sodalite) are generated. When 10wt.% of the cementitious material admixture is used to replace the slag powder in an equal amount for preparing unfired bricks, the compressive strength of the unfired bricks is reduced by 5-10%.

[0224] from Fig.10 , Fig.11 , Fig.12 , Fig.13 It can be seen that the main phases of fluorite tailings are quartz, calcite, mica, kaolinite, etc., and their SEM morphology is in the form of particles of different sizes; after being kept at a predetermined temperature for a period of time, the more active kaolinite and part of the calcite decompose and transform into hydrated calcium silicate ( Fig.10 ); Calcium silicate hydrate with low crystallinity ( Fig.12 ) is a gel-like, highly crystalline calcium silicate hydrate ( Fig.13 ) is in fibrous form, and the undecomposed quartz and mica, i.e., inert materials, are wrapped by the formed calcium silicate hydrate. The results show that fluorite tailings can be used to prepare cementitious admixtures, and the undecomposed quartz and mica have little effect on the application performance of the product.

[0225] from Fig.14 , Fig.15 It can be seen that bauxite tailings and coal tailings can also be used to prepare cementitious admixtures, and the microstructure of the reaction products is similar to Figure 3 , Figure 4 Consistent, calcium silicate hydrate with a lower degree of crystallization is in the form of gel ( Fig.14 ), calcium silicate hydrate with a higher degree of crystallization is fibrous ( Fig.15 ).

[0226] from Fig.16 It can be seen that the mixed slurry is relatively viscous at a too low liquid-to-solid ratio, resulting in poor energy and mass transfer effects, and there are still fluorite tailings particles that have not participated in the reaction in the reaction products (there is no hydrated calcium silicate gel attached to the surface of the particles).

[0227] from Fig.17 It can be seen that at lower temperatures, quartz, calcite, kaolinite and other components in fluorite tailings are almost insoluble, and the fine particles attached to the surface of fluorite tailings particles may be calcium hydroxide or calcium hydroxide formed by lime hydration.

[0228] from Fig.18It can be seen that at a higher reaction temperature, the coal mine tailings are fully dissolved in the alkaline solution and react with lime to produce fibrous calcium silicate hydrate and spherical zeolite with a higher degree of crystallization. Due to the low activity of calcium silicate hydrate and zeolite with a higher degree of crystallization, they have almost no contribution to the strength of the material, but instead reduce the strength of the material.

Claims

1. A method for preparing a cementitious material admixture, characterized in that: include: S1. According to a Ca / Si molar ratio of 0.1-1.0 and a liquid-to-solid ratio of 3-15 mL / g, slag, lime, activator and water are mixed to obtain a mixed slurry; S2, injecting the mixed slurry into a sealed container, stirring evenly, and then heating to 30-120° C., keeping warm for 0.1-10 hours, to obtain a reaction product; S3, separating the reaction product into solid and liquid, and obtaining a solid product as a cementitious material admixture.

2. The method for preparing a cementitious admixture according to claim 1, characterized in that: The liquid-to-solid ratio is 5-10 mL / g.

3. The method for preparing a cementitious admixture according to claim 1, characterized in that: The stirring linear speed is 100-300 m / s.

4. The method for preparing a cementitious admixture according to claim 3, characterized in that: The liquid-to-solid ratio is 8-15 mL / g, and the stirring linear speed is 100-200 m / s.

5. The method for preparing a cementitious admixture according to claim 3, characterized in that: When the liquid-to-solid ratio is 3-8 mL / g, the linear speed of stirring is 200-300 m / s.

6. The method for preparing a cementitious admixture according to claim 1, characterized in that: The activator is a water-soluble sodium salt or potassium salt.

7. The method for preparing a cementitious admixture according to claim 1, characterized in that: The heating temperature is 80-100°C.

8. A method for preparing a cementitious material admixture, characterized in that: include: S1. Mixing the beneficiation tailings, lime, an activator and water according to a Ca / Si molar ratio of 0.1-0.6 and a liquid-to-solid ratio of 3-15 mL / g to obtain a mixed slurry; S2, injecting the mixed slurry into a closed container, stirring evenly, and then heating to 90-200° C., keeping the temperature for 0.1-10 hours, to obtain a reaction product; S3, separating the reaction product into solid and liquid, and obtaining a solid product as a cementitious material admixture.

9. The method for preparing a cementitious admixture according to claim 8, characterized in that: The liquid-to-solid ratio is 5-10 mL / g.

10. The method for preparing a cementitious admixture according to claim 8, characterized in that: The heating temperature is 120-180°C.

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