Porous material and method for forming the same

Abstract

The invention discloses a porous material and a forming method thereof. The porous material comprises the following components in percentage by weight: 3 to 4.2 percent of Mg; from 14 wt% to 18 wt% of Ca; from 12 wt% to 15 wt% of Si; from 0.8 wt% to 1.5 wt% of Al; from 0.1 wt% to 0.3 wt% of K; from 0.4 wt% to 2 wt% of Fe; from 7 wt% to 8.5 wt% of Na; 4.8 wt% to 7.6 wt% of B; and from 48 wt% to 52 wt% of O.

Description

Technical Field

[0001] The present invention relates to porous materials, and more particularly to porous lightweight materials produced by recycling waste, and methods for forming such porous lightweight materials. Background Art

[0002] According to recent statistics in the steel industry, the amount of BOF slag (BOFS) and EAF slag (EAFS) generated by the global steel industry each year is approximately 500 million tons / year. The expected output of the derived reduced slag and waste refractories is also quite high. The reduced slag and waste refractories contain excessive free calcium oxide (f-CaO) and free magnesium oxide (f-MgO). After contacting with water, calcium hydroxide (Ca(OH)2) and magnesium hydroxide (Mg(OH) 2 ) will be produced respectively, that is, the volume expands to about one to three times of the original volume. Since the quality of the reduced slag and waste refractories is not easy to maintain stable, it is difficult to recycle. The traditional methods for treating the reduced slag and waste refractories require dehydration and addition of curing agents before landfilling, which are not only time-consuming, laborious, but also costly.

[0003] There is an urgent need for new methods to treat the reduced slag and waste refractories, and even recycle them to prepare materials that meet the requirements of construction projects. Summary of the Invention

[0004] The porous material provided by an embodiment of the present invention includes: 3 wt% to 4.2 wt% of Mg; 14 wt% to 18 wt% of Ca; 12 wt% to 15 wt% of Si; 0.8 wt% to 1.5 wt% of Al; 0.1 wt% to 0.3 wt% of K; 0.4 wt% to 2 wt% of Fe; 7 wt% to 8.5 wt% of Na; 4.8 wt% to 7.6 wt% of B; and 48 wt% to 52 wt% of O.

[0005] In some embodiments, the porous material has Na 2 MgSiO 4 , Na 2 Si(Si 2 O 7 ), CaMgSi 2 O 6 , MgO, CaSiO 3 or a combination of the above crystalline phases.

[0006] In some embodiments, the porous material has a honeycomb structure, with a porosity of 13% to 25% and a pore size of 5 microns to 450 microns.

[0007] In some embodiments, the compressive strength of the porous material is 200 kgf / cm 2 to 400 kgf / cm 2, with a density of 1.5 g / cm 3 to 1.65 g / cm 3 , and the water absorption rate is 5% to 20%.

[0008] In some embodiments, the thermal conductivity coefficient of the porous material is 0.4 W / m·k to 0.8 W / m·k, and the porous material has fire resistance and heat insulation properties against flames at 1000 °C to 1200 °C.

[0009] A method for forming a porous material provided by an embodiment of the present invention includes: mixing raw materials, an alkali activator, and a foaming agent to obtain a mixture, where the raw materials include 40 wt% to 45 wt% of reduced slag, 10 wt% to 15 wt% of waste refractory, and 40 wt% to 45 wt% of waste glass; pouring the mixture into a mold to form a green body; and calcining the green body to form the above-mentioned porous material, where the calcination temperature is 600 °C to 800 °C, and the time is 1 hour to 4 hours.

[0010] In some embodiments, the reduced slag includes: 1 wt% to 10 wt% of Mg, 30 wt% to 45 wt% of Ca, 5 wt% to 20 wt% of Si, 1 wt% to 5 wt% of Al, 0.5 wt% to 1.5 wt% of B, 40 wt% to 50 wt% of O, 0.01 wt% to 0.1 wt% of K, 0.1 wt% to 0.5 wt% of Na, and 0.1 wt% to 1 wt% of Fe.

[0011] In some embodiments, the waste refractory includes: 20 wt% to 30 wt% of Mg, 20 wt% to 30 wt% of Ca, 1 wt% to 5 wt% of Si, 3 wt% to 4 wt% of Al, 35 wt% to 45 wt% of O, 0.1 wt% to 1 wt% of B, 0.01 wt% to 1 wt% of Na, 0.01 wt% to 1 wt% of K, and 0.5 wt% to 1 wt% of Fe.

[0012] In some embodiments, the waste glass includes: 45 wt% to 55 wt% of O, 20 wt% to 30 wt% of Si, 1 wt% to 5 wt% of B, 0.1 wt% to 1 wt% of Fe, 1 wt% to 5 wt% of Al, 0.1 wt% to 1 wt% of K, 0.1 wt% to 1 wt% of Mg, 5 wt% to 10 wt% of Na, and 5 wt% to 10 wt% of Ca.

[0013] In some embodiments, the alkali activator includes sodium hydroxide, potassium hydroxide, calcium oxide, sodium carbonate, sodium silicate, or a combination of the above, and the foaming agent includes boric acid, sodium bicarbonate (NaHNO 3 ), sodium perborate (NaBO 3 ), borax, silicon carbide (SiC), or a combination of the above.

[0014] In some embodiments, the weight ratio of the raw materials to the alkali activator is from 100:1 to 100:10, and the weight ratio of the raw materials to the foaming agent is from 100:10 to 100:15.

[0015] In some embodiments, the reduced slag is a by-product of the metallurgical industry, and the waste refractory is a discarded high-temperature industrial equipment. Detailed implementation manners

[0016] A method for forming a porous material provided by an embodiment of the present invention includes: mixing raw materials, an alkali activator and a foaming agent to obtain a mixture. The raw materials include 40wt% to 45wt% of reduced slag, 10wt% to 15wt% of waste refractory, and 40wt% to 45wt% of waste glass. In some embodiments, the reduced slag is a by-product of the metallurgical industry, and the waste refractory is a discarded high-temperature industrial equipment.

[0017] In some embodiments, the reduced slag includes: 1wt% to 10wt% of Mg, 30wt% to 45wt% of Ca, 5wt% to 20wt% of Si, 1wt% to 5wt% of Al, 0.5wt% to 1.5wt% of B, 40wt% to 50wt% of O, 0.01wt% to 0.1wt% of K, 0.1wt% to 0.5wt% of Na, and 0.1wt% to 1wt% of Fe. From the above composition, it can be seen that the reduced slag contains a large amount of calcium.

[0018] In some embodiments, the reduced slag may include, for example, 2wt%, 3wt%, 5wt%, 8wt% of Mg, but not limited thereto. The reduced slag may include, for example, 32wt%, 35wt%, 38wt%, 40wt%, 42wt% of Ca, but not limited thereto. The reduced slag may include, for example, 7wt%, 10wt%, 12wt%, 15wt%, 18wt% of Si, but not limited thereto. The reduced slag may include, for example, 1.2wt%, 2wt%, 3wt%, 4.5wt% of Al, but not limited thereto. The reduced slag may include, for example, 0.75wt%, 1.0wt%, 1.25wt%, 1.45wt% of B, but not limited thereto. The reduced slag may include, for example, 42wt%, 43wt%, 45wt%, 48wt% of O, but not limited thereto. The reduced slag may include, for example, 0.02wt%, 0.05wt%, 0.075wt% of K, but not limited thereto. The reduced slag may include, for example, 0.15wt%, 0.2wt%, 0.3wt%, 0.45wt% of Na, but not limited thereto. The reduced slag may include, for example, 0.2wt%, 0.3wt%, 0.5wt%, 0.75wt%, 0.8wt% of Fe, but not limited thereto.

[0019] In some embodiments, the waste refractory material comprises: 20 wt% to 30 wt% Mg, 20 wt% to 30 wt% Ca, 1 wt% to 5 wt% Si, 3 wt% to 4 wt% Al, 35 wt% to 45 wt% O, 0.1 wt% to 1 wt% B, 0.01 wt% to 1 wt% Na, 0.01 wt% to 1 wt% K, and 0.5 wt% to 1 wt% Fe. From the above composition, it can be seen that the waste refractory material contains a large amount of calcium and magnesium.

[0020] In some embodiments, the waste refractory material may include, for example, 22 wt%, 25 wt%, 27 wt%, 29 wt% Mg, but not limited thereto. The waste refractory material may include, for example, 22.5 wt%, 25 wt%, 27.5 wt%, 29 wt% Ca, but not limited thereto. The waste refractory material may include, for example, 1.5 wt%, 1.75 wt%, 2 wt%, 3 wt%, 4.5 wt% Si, but not limited thereto. The waste refractory material may include, for example, 3.2 wt%, 3.5 wt%, 3.75 wt%, 3.9 wt% Al, but not limited thereto. The waste refractory material may include, for example, 37.5 wt%, 40 wt%, 42.5 wt%, 44 wt% O, but not limited thereto. The waste refractory material may include, for example, 0.15 wt%, 0.25 wt%, 0.5 wt%, 0.75 wt% B, but not limited thereto. The waste refractory material may include, for example, 0.05 wt%, 0.1 wt%, 0.5 wt%, 0.75 wt% Na, but not limited thereto. The waste refractory material may include, for example, 0.05 wt%, 0.1 wt%, 0.5 wt%, 0.75 wt% K, but not limited thereto. The waste refractory material may include, for example, 0.6 wt%, 0.75 wt%, 0.9 wt% Fe, but not limited thereto.

[0021] In some embodiments, the waste glass comprises: 45 wt% to 55 wt% O, 20 wt% to 30 wt% Si, 1 wt% to 5 wt% B, 0.1 wt% to 1 wt% Fe, 1 wt% to 5 wt% Al, 0.1 wt% to 1 wt% K, 0.1 wt% to 1 wt% Mg, 5 wt% to 10 wt% Na, and 5 wt% to 10 wt% Ca. From the above composition, it can be seen that the waste glass contains a large amount of silicon.

[0022] In some embodiments, the waste glass may include, for example, O in amounts of 47.5 wt%, 50 wt%, 52.5 wt%, 54 wt%, but is not limited thereto. The waste glass may include, for example, Si in amounts of 22.5 wt%, 25 wt%, 27.5 wt%, but is not limited thereto. The waste glass may include, for example, B in amounts of 1.25 wt%, 1.5 wt%, 2.5 wt%, 3.75 wt%, 4.5 wt%, but is not limited thereto. The waste glass may include, for example, Fe in amounts of 0.25 wt%, 0.5 wt%, 0.75 wt%, but is not limited thereto. The waste glass may include, for example, Al in amounts of 1.25 wt%, 1.75 wt%, 2.5 wt%, 3.75 wt%, 4.5 wt%, but is not limited thereto. The waste glass may include, for example, K in amounts of 0.25 wt%, 0.5 wt%, 0.75 wt%, but is not limited thereto. The waste glass may include, for example, Mg in amounts of 0.25 wt%, 0.5 wt%, 0.75 wt%, 0.85 wt%, but is not limited thereto. The waste glass may include, for example, Na in amounts of 5.5 wt%, 7.5 wt%, 8.5 wt%, 9.5 wt%, but is not limited thereto. The waste glass may include, for example, Ca in amounts of 5.5 wt%, 7.5 wt%, 8.5 wt%, 9.5 wt%, but is not limited thereto.

[0023] Next, the mixture is molded to form a green body, and then the green body is calcined to form a porous material. The calcination temperature is from 600 °C to 800 °C, and may be, for example, 650 °C, 675 °C, 700 °C, 750 °C, etc., but is not limited thereto. The calcination time is from 1 hour to 4 hours, and may be, for example, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, etc., but is not limited thereto. If the calcination temperature is too low or the calcination time is too short, the density of the resulting product is too high (it cannot be lightened) and the compressive strength is insufficient. If the calcination temperature is too high or the calcination time is too long, the water absorption rate of the resulting product is too high and the compressive strength is insufficient.

[0024] In some embodiments, the alkali activator includes sodium hydroxide, potassium hydroxide, calcium oxide, sodium carbonate, sodium silicate, or a combination of the above, and the foaming agent includes boric acid, sodium bicarbonate (NaHNO 3 )、sodium perborate (NaBO 3 ), borax, silicon carbide (SiC), or a combination of the above.

[0025] In some embodiments, the weight ratio of the raw material to the alkali activator is from 100:1 to 100:10, such as 100:2, 100:3, 100:5, 100:7, 100:8.5, etc., but not limited thereto. The weight ratio of the raw material to the foaming agent is from 100:10 to 100:15, such as 100:10, 100:12.5, or 100:15, etc., but not limited thereto. If the dosage of the alkali activator is too low, the raw material cannot undergo an inorganic polymerization reaction to produce a honeycomb-like pore structure. If the dosage of the alkali activator is too high, there will be a whitening phenomenon, forming too much sodium bicarbonate and possibly reducing the compressive strength. If the dosage of the foaming agent is too low, the density of the resulting product is too high (it cannot be light-weighted) and the compressive strength is insufficient. If the dosage of the foaming agent is too high, the water absorption rate of the resulting product is too high and the compressive strength is insufficient.

[0026] In some embodiments, the porous material formed by the above method comprises: 3 wt% to 4.2 wt% of Mg, 14 wt% to 18 wt% of Ca, 12 wt% to 15 wt% of Si, 0.8 wt% to 1.5 wt% of Al, 0.1 wt% to 0.3 wt% of K, 0.4 wt% to 2 wt% of Fe, 7 wt% to 8.5 wt% of Na, 4.8 wt% to 7.6 wt% of B, and 48 wt% to 52 wt% of O.

[0027] In some embodiments, the above-mentioned porous material may include, for example, Mg at 3.1 wt%, 3.25 wt%, 3.75 wt%, 4.0 wt%, 4.15 wt%, but not limited thereto. The above-mentioned porous material may include, for example, Ca at 14.5 wt%, 15 wt%, 15.5 wt%, 16.5 wt%, 17 wt%, 17.5 wt%, 17.75 wt%, but not limited thereto. The above-mentioned porous material may include, for example, Si at 12.5 wt%, 13 wt%, 13.5 wt%, 14 wt%, 14.5 wt%, but not limited thereto. The above-mentioned porous material may include, for example, Al at 0.85 wt%, 1.0 wt%, 1.15 wt%, 1.3 wt%, 1.45 wt%, but not limited thereto. The above-mentioned porous material may include, for example, K at 0.15 wt%, 0.2 wt%, 0.25 wt%, 0.28 wt%, but not limited thereto. The above-mentioned porous material may include, for example, Fe at 0.45 wt%, 0.5 wt%, 1.0 wt%, 1.25 wt%, 1.5 wt%, 1.75 wt%, but not limited thereto. The above-mentioned porous material may include, for example, Na at 7.25 wt%, 7.5 wt%, 7.75 wt%, 8.0 wt%, 8.25 wt%, but not limited thereto. The above-mentioned porous material may include, for example, B at 5.0 wt%, 5.5 wt%, 6.0 wt%, 6.5 wt%, 7.0 wt%, 7.5 wt%, but not limited thereto. The above-mentioned porous material may include, for example, O at 48.5 wt%, 49.0 wt%, 49.5 wt%, 50.0 wt%, 51.5 wt%, but not limited thereto. If the content of Mg / Ca is too low, it cannot be used as a sintering melting point reducing flux. If the content of Mg / Ca is too high, too much magnesium hydroxide / calcium hydroxide swelling product will be formed. If the content of Si / Al / Na is too low, silicon-aluminum ions cannot be effectively dissolved out. If the content of Si / Al / Na is too high, excessive silicon-aluminum ions cannot effectively generate a charge-balanced framework structure.

[0028] In the above-mentioned porous material, if the contents of Mg and Ca are too low, it will be insufficient as a flux for reducing the sintering melting point. If the contents of Mg and Ca are too high, it can be expected that too much magnesium hydroxide and calcium hydroxide swelling products will be formed. Also, in the above-mentioned porous material, if the contents of Si, Al, and Na are too low, a stable framework structure cannot be effectively formed. If the contents of Si, Al, and Na are too high, it is not easy to generate a charge-balanced framework structure.

[0029] In some embodiments, the porous material has Na 2 MgSiO 4 、Na 2 Si(Si 2 O 7 )、CaMgSi 2 O6 , MgO, CaSiO 3 or a crystal phase of the above combinations. These crystal phases help improve the compressive strength of the porous material.

[0030] In some embodiments, the porous material has a honeycomb structure, with a porosity of 13% to 25% and pore sizes of 5 microns to 450 microns. For example, it can be 5 microns to 10 microns, 10 microns to 15 microns, 15 microns to 25 microns, 25 microns to 150 microns, 20 microns to 100 microns, 50 microns to 200 microns, 150 microns to 450 microns, or 240 microns to 450 microns, but not limited thereto. If the porosity of the porous material is too low, the effect of material lightening cannot be achieved. If the porosity of the porous material is too high, the water absorption rate is too large, resulting in a decrease in structural strength. If the pore size of the porous material is too small, it does not have heat insulation and fire resistance properties. If the pore size of the porous material is too large, the structural strength is insufficient and it is difficult to process.

[0031] In some embodiments, the compressive strength of the porous material is 200 kgf / cm 2 to 400 kgf / cm 2 , for example, it can be 210 kgf / cm 2 , 250 kgf / cm 2 , 275 kgf / cm 2 , 300 kgf / cm 2 , 350 kgf / cm 2 , 375 kgf / cm 2 etc., but not limited thereto. The density of the porous material is 1.5 g / cm 3 to 1.65 g / cm 3 , for example, it can be 1.52 g / cm 3 , 1.55 g / cm 3 , 1.58 g / cm 3 , 1.6 g / cm 3 , 1.62 g / cm 3 etc., but not limited thereto. The water absorption rate of the porous material is 5% to 20%, for example, it can be 7.5%, 8%, 9.5%, 10%, 12.5%, 15%, 17.5%, etc., but not limited thereto. If the compressive strength of the porous material is insufficient, it cannot replace sand and gravel in the application of building materials. If the density of the porous material is too small, the strength is insufficient and it is difficult to process. If the density of the porous material is too large, the effect of lightening cannot be achieved.

[0032] In some embodiments, the thermal conductivity of the porous material is from 0.4 W / m·K to 0.8 W / m·K, and for example, it may be 0.5 W / m·K, 0.6 W / m·K, 0.7 W / m·K, etc., but not limited thereto. And the porous material has fire resistance and heat insulation against flames at 1000 °C to 1200 °C (such as 1100 °C). If the thermal conductivity of the porous material is too large, there will be no heat insulation effect.

[0033] The above honeycomb-shaped porous material can be used as a lightweight aggregate in the construction industry, which can greatly save construction costs and solve the problems of treating recycled slag, waste refractory materials, and waste glass.

[0034] To make the above content, other objects, features, and advantages of the present invention more obvious and understandable, specific embodiments are hereinafter given and described in detail as follows:

[0035] [Embodiment]

[0036] In one embodiment, the recycled slag includes 45.61 wt% of O, 0.94 wt% of B, 0.18 wt% of Fe, 1.08 wt% of Al, 10.91 wt% of Si, 0.01 wt% of K, 0.16 wt% of Na, 38.51 wt% of Ca, and 2.59 wt% of Mg. The waste refractory material includes 43.92 wt% of O, 0.51 wt% of B, 0.73 wt% of Fe, 3.66 wt% of Al, 3.17 wt% of Si, 0.04 wt% of K, 0.04 wt% of Na, 25.67 wt% of Ca, and 22.28 wt% of Mg. The waste glass includes 51.09 wt% of O, 1.32 wt% of B, 0.24 wt% of Fe, 1.18 wt% of Al, 28.79 wt% of Si, 0.53 wt% of K, 8.88 wt% of Na, 7.11 wt% of Ca, and 0.82 wt% of Mg.

[0037] In another embodiment, the reduced slag comprises 45.88 wt% O, 0.97 wt% B, 0.16 wt% Fe, 1.01 wt% Al, 10.55 wt% Si, 0.02 wt% K, 0.15 wt% Na, 38.44 wt% Ca, and 2.52 wt% Mg. The waste refractory comprises 43.88 wt% O, 0.53 wt% B, 0.76 wt% Fe, 3.45 wt% Al, 3.22 wt% Si, 0.05 wt% K, 0.06 wt% Na, 25.81 wt% Ca, and 22.33 wt% Mg. The waste glass comprises 51.12 wt% O, 1.28 wt% B, 0.29 wt% Fe, 1.22 wt% Al, 28.81 wt% Si, 0.56 wt% K, 8.97 wt% Na, 7.21 wt% Ca, and 0.88 wt% Mg.

[0038] In yet another embodiment, the reduced slag comprises 45.55 wt% O, 0.91 wt% B, 0.13 wt% Fe, 1.04 wt% Al, 10.78 wt% Si, 0.06 wt% K, 0.12 wt% Na, 38.49 wt% Ca, and 2.54 wt% Mg. The waste refractory comprises 43.87 wt% O, 0.49 wt% B, 0.68 wt% Fe, 3.68 wt% Al, 3.25 wt% Si, 0.09 wt% K, 0.07 wt% Na, 25.74 wt% Ca, and 22.35 wt% Mg. The waste glass comprises 51.12 wt% O, 1.35 wt% B, 0.26 wt% Fe, 1.19 wt% Al, 28.81 wt% Si, 0.55 wt% K, 8.89 wt% Na, 7.16 wt% Ca, and 0.85 wt% Mg.

[0039] The elemental ratios of the above-mentioned reduced slag, waste refractory, waste glass, and the products of the following examples and comparative examples are measured by X-ray fluorescence spectrometer (XRF). The density of the products of the examples and comparative examples is measured by ASTM C373, the water absorption rate is measured by ASTM C12, the compressive strength is measured by ASTM C109, the porosity is measured by ASTM C29, the pore size is measured by measuring the pore size through SEM microstructure, the thermal conductivity is measured by ASTM C109, and the fire resistance is measured by ASTM E119.

[0040] Example 1

[0041] Take 270 g of reduced slag, 90 g of waste refractory, and 258 g of waste glass as raw materials. Prepare 210 mL of 4 M NaOH solution (containing 36 g of NaOH) as an alkali activator. Mix the raw materials and the alkali activator, then add 80 g of boric acid (about 13%) as a foaming agent and stir evenly. After pouring into a mold, press and form at 3500 psi and air-dry for one day, then dry in an oven at 60 °C and calcine at 600 °C for 4 hours to obtain a porous material with a density of 1.62 g / cm 3 , a water absorption rate of 8.88%, and a compressive strength of 206 kgf / cm 2 , a porosity of 13.8%, pore sizes ranging from 5.76 microns to 10 microns, and a thermal conductivity of 0.75 W / m·K. This porous material contains 52.01 wt% of O, 7.58 wt% of B, 0.47 wt% of Fe, 0.87 wt% of Al, 13.29 wt% of Si, 0.19 wt% of K, 8.06 wt% of Na, 14.42 wt% of Ca, and 3.07 wt% of Mg. From XRD analysis, it can be seen that the porous material has CaMgSi 2 O 6 , MgO, and CaSiO 3 crystal phases.

[0042] Example 2

[0043] Take 270 g of reduced slag, 90 g of waste refractory, and 258 g of waste glass as raw materials. Prepare 210 mL of 4 M NaOH solution (containing 36 g of NaOH) as an alkali activator. Mix the raw materials and the alkali activator, then add 80 g of boric acid (about 13%) as a foaming agent and stir evenly. After pouring into a mold, press and form at 3500 psi and air-dry for one day, then dry in an oven at 60 °C and calcine at 650 °C for 4 hours to obtain a porous material with a density of 1.6 g / cm 3 , a water absorption rate of 7.45%, and a compressive strength of 272 kgf / cm 2 , a porosity of 16.1%, pore sizes ranging from 16.36 microns to 22.73 microns, and a thermal conductivity of 0.68 W / m·K. This porous material contains 50.39 wt% of O, 4.98 wt% of B, 0.51 wt% of Fe, 1.09 wt% of Al, 14.69 wt% of Si, 0.22 wt% of K, 7.53 wt% of Na, 16.58 wt% of Ca, and 3.95 wt% of Mg. From XRD analysis, it can be seen that the porous material has Na 2 MgSiO 4 , Na 2 Si(Si 2 O 7 ), CaMgSi 2 O6 , MgO, and CaSiO 3 crystalline phases.

[0044] Example 3

[0045] Take 270 g of reduced slag, 90 g of waste refractory, and 258 g of waste glass as raw materials. Prepare 210 mL of 4 M NaOH solution (containing 36 g of NaOH) as an alkali activator. Mix the raw materials and the alkali activator, then add 80 g of boric acid (about 13%) as a foaming agent and stir evenly. After pouring into a mold, press-mold at 3500 psi and air-dry for one day, then dry in an oven at 60 °C and calcine at 700 °C for 4 hours to obtain a porous material with a density of 1.5 g / cm 3 , a water absorption rate of 9.75%, and a compressive strength of 370 kgf / cm 2 , a porosity of 19.3%, pore sizes ranging from 163 microns to 439 microns, and a thermal conductivity of 0.51 W / m·K. This porous material contains 49.62 wt% O, 5.30 wt% B, 0.49 wt% Fe, 1.13 wt% Al, 13.69 wt% Si, 0.23 wt% K, 7.67 wt% Na, 17.69 wt% Ca, and 4.14 wt% Mg. From XRD analysis, it can be seen that the porous material has Na 2 MgSiO 4 , Na 2 Si(Si 2 O 7 ), CaMgSi 2 O 6 , MgO, and CaSiO 3 crystalline phases.

[0046] Example 4

[0047] Take 270 g of reduced slag, 90 g of waste refractory, and 258 g of waste glass as raw materials. Prepare 210 mL of 4 M NaOH solution (containing 36 g of NaOH) as an alkali activator. Mix the raw materials and the alkali activator, then add 80 g of boric acid (about 13%) as a foaming agent and stir evenly. After pouring into a mold, press-mold at 3500 psi and air-dry for one day, then dry in an oven at 60 °C and calcine at 800 °C for 4 hours to obtain a porous material with a density of 1.59 g / cm 3 , a water absorption rate of 17.21%, and a compressive strength of 217 kgf / cm 2, with a porosity of 23.3%, pore sizes ranging from 249 microns to 436.36 microns, and a thermal conductivity of 0.47 W / m.k. This porous material consists of 51.07 wt% O, 5.54 wt% B, 1.66 wt% Fe, 0.92 wt% Al, 12.53 wt% Si, 0.17 wt% K, 7.75 wt% Na, 17.05 wt% Ca, and 3.27 wt% Mg. As analyzed by XRD, the porous material has Na 2 Si(Si 2 O 7 ), CaMgSi 2 O 6 , and CaSiO 3 crystal phases.

[0048] Comparative Example 1

[0049] Take 270 g of reduced slag, 90 g of waste refractory, and 258 g of waste glass as raw materials. Prepare 210 mL of 4M NaOH solution (containing 36 g of NaOH) as the alkali activator. Mix the raw materials and the alkali activator and stir evenly. After pouring into the mold, press and form at 3500 psi, then air-dry for one day, further dry in an oven at 60°C, and calcine at 600°C for 4 hours to obtain a non-porous material with a density of 1.86 g / cm 3 , a water absorption rate of 20.07%, and a compressive strength of 43 kgf / cm 2 . From Comparative Example 1, it can be seen that the non-porous material without a foaming agent has too high a density and too low a compressive strength.

[0050] Comparative Example 2

[0051] Take 270 g of reduced slag, 90 g of waste refractory, and 258 g of waste glass as raw materials. Prepare 210 mL of 4M NaOH solution (containing 36 g of NaOH) as the alkali activator. Mix the raw materials and the alkali activator, then add 18.5 g of boric acid (about 3%) as the foaming agent and stir evenly. After pouring into the mold, press and form at 3500 psi, then air-dry for one day, further dry in an oven at 60°C, and calcine at 600°C for 4 hours to obtain a porous material with a density of 1.82 g / cm 3 , a water absorption rate of 19.96%, and a compressive strength of 68 kgf / cm 2 . From Comparative Example 2, it can be seen that the porous material with too low an amount of foaming agent has too high a density and too low a compressive strength.

[0052] Comparative Example 3

[0053] Take 270 g of reduced slag, 90 g of waste refractory, and 258 g of waste glass as raw materials. Prepare 210 mL of 4 M NaOH solution (containing 36 g of NaOH) as an alkali activator. Mix the raw materials and the alkali activator, then add 43.3 g of boric acid (about 7%) as a foaming agent and stir evenly. After pouring into a mold, press and form at 3500 psi and air-dry for one day, then dry in an oven at 60 °C, and calcine at 600 °C for 4 hours to obtain a porous material with a density of 1.68 g / cm 3 , water absorption rate of 17.22%, and compressive strength of 85 kgf / cm 2 . As can be seen from Comparative Example 3, the porous material with too low an amount of foaming agent has too high a density and too low a compressive strength.

[0054] Comparative Example 4

[0055] Take 270 g of reduced slag, 90 g of waste refractory, and 258 g of waste glass as raw materials. Prepare 210 mL of 4 M NaOH solution (containing 36 g of NaOH) as an alkali activator. Mix the raw materials and the alkali activator, then add 123.6 g of boric acid (about 20%) as a foaming agent and stir evenly. After pouring into a mold, press and form at 3500 psi and air-dry for one day, then dry in an oven at 60 °C, and calcine at 600 °C for 4 hours to obtain a porous material with a density of 1.49 g / cm 3 , water absorption rate of 28.33%, and compressive strength of 123 kgf / cm 2 . As can be seen from Comparative Example 4, the porous material with too high an amount of foaming agent has too low a density and too low a compressive strength.

[0056] Comparative Example 5

[0057] Take 270 g of reduced slag, 90 g of waste refractory, and 258 g of waste glass as raw materials. Prepare 210 mL of 4 M NaOH solution (containing 36 g of NaOH) as an alkali activator. Mix the raw materials and the alkali activator, then add 80 g of boric acid (about 13%) as a foaming agent and stir evenly. After pouring into a mold, press and form at 3500 psi and air-dry for one day, then dry in an oven at 60 °C, and place at room temperature for 7 days to obtain a material with a density of 1.81 g / cm 3 , water absorption rate of 15.11%, compressive strength of 49 kgf / cm 2, and the thermal conductivity is 1.14 W / m·K, and no obvious pores are generated in this material. This material without obvious pores (hereinafter referred to as non-porous material) includes 53.79 wt% of O, 3.14 wt% of B, 0.29 wt% of Fe, 0.95 wt% of Al, 16.7 wt% of Si, 0.21 wt% of K, 6.50 wt% of Na, 16.17 wt% of Ca, and 2.13 wt% of Mg. It can be known from XRD analysis that the non-porous material has the crystal phases of SiO 2 , MgO, and CaSiO 3 . It can be known from Comparative Example 5 that the density of the uncalcined product such as the non-porous material is relatively high and the compressive strength is relatively low.

[0058] Fire resistance and heat insulation test

[0059] The non-porous materials of Example 3 and Comparative Example 5 above were respectively sprayed with a flame at 1100 °C for 30 minutes. The temperature of the porous material of Example 3 was 158 °C and the appearance changed little, while the temperature of the non-porous material of Comparative Example 5 was 262 °C and there were obvious burning marks on the appearance. It can be seen from the above that the porous material of Example 3 has fire resistance and heat insulation against a 1100 °C flame.

[0060] Comparative Example 6

[0061] Take 270 g of reduced slag, 90 g of waste refractory, and 258 g of waste glass as raw materials. Prepare 210 mL of 4 M NaOH solution (containing 36 g of NaOH) as an alkali activator. Mix the raw materials and the alkali activator, then add 80 g of boric acid (about 13%) as a foaming agent and stir evenly. After pouring into a mold, it was pressed and formed at 3500 psi and air-dried for one day, then dried in an oven at 60 °C, and calcined at 500 °C for 4 hours to obtain a porous material with a density of 1.76 g / cm 3 , a water absorption rate of 14.88%, a compressive strength of 115 kgf / cm 2 , a porosity of 12.5%, a pore size of 2.31 to 5.01 microns, and a thermal conductivity of 1.089 W / m·K. This porous material includes 50.32 wt% of O, 4.52 wt% of B, 0.36 wt% of Fe, 0.91 wt% of Al, 16.81 wt% of Si, 0.22 wt% of K, 6.66 wt% of Na, 17.72 wt% of Ca, and 2.44 wt% of Mg. It can be known from XRD analysis that the porous material has the crystal phases of CaMgSi 2 O 6 , MgO, and CaSiO 3 . It can be known from Comparative Example 6 that the products with too low calcination temperature have relatively high density and relatively low compressive strength.

[0062] Comparative Example 7

[0063] Take 270 g of reduced slag, 90 g of waste refractory, and 258 g of waste glass as raw materials. Prepare 210 mL of 4 M NaOH solution (containing 36 g of NaOH) as an alkali activator. Mix the raw materials and the alkali activator, then add 80 g of boric acid (about 13%) as a foaming agent and stir evenly. After pouring into a mold, press-mold at 3500 psi and air-dry for one day, then dry in an oven at 60 °C, and calcine at 900 °C for 4 hours to obtain a porous material with a density of 1.58 g / cm 3 , water absorption rate of 27.88%, and compressive strength of 109 kgf / cm 2 , porosity of 26.8%, pore size ranging from 248.48 microns to 724.24 microns, and thermal conductivity of 0.42 W / m·K. This porous material includes 47.65 wt% of O, 4.07 wt% of B, 5.35 wt% of Fe, 1.60 wt% of Al, 13.44 wt% of Si, 0.18 wt% of K, 6.09 wt% of Na, 17.87 wt% of Ca, and 3.70 wt% of Mg. It can be seen from XRD analysis that the porous material has Na 2 Si(Si 2 O 7 ), CaMgSi 2 O 6 , and CaSiO 3 crystal phases. It can be seen from Comparative Example 7 that the product with too high a calcination temperature has a high water absorption rate and a low compressive strength.

[0064] Although the present invention has been disclosed above with several embodiments, it is not intended to limit the present invention. Any person with ordinary knowledge in the technical field can make any changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the appended claims.

Claims

1. A porous material comprising: 3 to 4.2 wt% Mg; 14 to 18 wt% Ca; 12 wt % to 15 wt % Si; 0.8 wt% to 1.5 wt% Al; 0.1 wt% to 0.3 wt% K; 0.4 to 2 wt% Fe; 7 to 8.5 wt% Na; 4.8 wt% to 7.6 wt% of B; and 48wt% to 52wt% O.

2. The porous material according to claim 1, wherein the porous material has a crystalline phase of Na2MgSiO4, Na2Si(Si2O7), CaMgSi2O6, MgO, CaSiO3 or a combination thereof. 3 . The porous material according to claim 1 , wherein the porous material has a honeycomb structure, a porosity of 13% to 25%, and a pore size of 5 μm to 450 μm.

4. The porous material according to claim 1, wherein the compressive strength of the porous material is 200 kgf / cm 2 Up to 400kgf / cm 2 , density is 1.5g / cm 3 Up to 1.65g / cm 3 , and the water absorption rate is 5% to 20%. 5 . The porous material according to claim 1 , wherein the thermal conductivity of the porous material is 0.4 W / m·k to 0.8 W / m·k, and the porous material has fireproof and heat insulating properties against flames of 1000° C. to 1200° C.

6. A method for forming a porous material, comprising: Mixing a raw material, an alkali activator and a foaming agent to obtain a mixture, wherein the raw material comprises 40wt% to 45wt% of reduced slag, 10wt% to 15wt% of waste refractory materials and 40wt% to 45wt% of waste glass; casting the mixture into a mold to form a green body; and The green body is calcined to form the porous material according to claim 1, wherein the calcination temperature is 600°C to 800°C and the calcination time is 1 hour to 4 hours.

7. The method for forming a porous material according to claim 6, wherein the reduced slag comprises: 1 to 10 wt % Mg; 30 to 45 wt% Ca; 5 to 20 wt % Si; 1 to 5 wt% Al; 0.5 wt% to 1.5 wt% of B; 40 to 50 wt% O; 0.01 wt% to 0.1 wt% K; 0.1 wt% to 0.5 wt% Na; as well as 0.1 wt% to 1 wt% Fe.

8. The method for forming a porous material according to claim 6, wherein the waste refractory material comprises: 20 to 30 wt % Mg; 20 to 30 wt% Ca; 1 wt% to 5 wt% Si; 3 to 4 wt% Al; 35 to 45 wt% O; 0.1 wt% to 1 wt% of B; 0.01 wt % to 1 wt % of Na; 0.01 wt % to 1 wt % of K; as well as 0.5wt% to 1wt% Fe.

9. The method for forming a porous material according to claim 6, wherein the waste glass comprises: 45 to 55 wt% O; 20 wt % to 30 wt % Si; 1 wt% to 5 wt% of B; 0.1 wt% to 1 wt% Fe; 1 to 5 wt% Al; 0.1 wt% to 1 wt% K; 0.1 wt% to 1 wt% Mg; 5 to 10 wt % of Na; as well as 5wt% to 10wt% Ca.

10. The method for forming a porous material according to claim 6, wherein the alkaline activator comprises sodium hydroxide, potassium hydroxide, calcium oxide, sodium carbonate, sodium silicate or a combination thereof, and the foaming agent comprises boric acid, sodium bicarbonate (NaHNO3), sodium perborate (NaBO3), borax, silicon carbide (SiC) or a combination thereof. 11 . The method for forming a porous material according to claim 6 , wherein a weight ratio of the raw material to the alkali activator is 100:1 to 100:10, and a weight ratio of the raw material to the foaming agent is 100:10 to 100:

15.

12. The method for forming a porous material according to claim 6, wherein the reduced slag is a by-product of the metallurgical industry, and the waste refractory material is waste high-temperature industrial equipment.