TW202308961A - Method of manufacturing inorganic binder and cured solid manufactured by the method - Google Patents

Abstract

A method of manufacturing an inorganic cementing material includes a raw material preparation step, a stirring step, a maintaining step and a drying step. The raw material preparation step is to provide a powder mixture including welding slag powder and glass powder. In the powder mixture, the welding slag powder accounts for 5wt% to 50wt%, and the glass powder accounts for 50wt% to 95wt%. The slag powder contains 18wt% to 30wt% of SiO2 and 10wt% to 20wt% of Al2O3, and the glass powder contains more than 85wt% of SiO2. The stirring step is to place the powder mixture in a mixing tank, and add an alkali activator to the mixing tank to stir and react to form mixed slurry. The alkali equivalent of the mixed slurry is 2% to 9%, and the water-binder ratio is 0.25 to 0.4. The maintaining step is to place the mixed slurry in a maintaining environment for a maintaining time to get a binder, wherein the temperature of the maintaining environment is 60 to 80 degrees Celsius, and the maintaining time is at least 16 hours. The drying step is to dry the binder.

Description

Manufacturing method of inorganic binder and cured product thereof

The invention relates to the field of waste recycling, in particular to a method for manufacturing an inorganic binder and a cured product formed therefrom.

Welding is an important method for assembling steel structure components in machinery, shipbuilding and construction industries. The current common welding technology is arc welding (Arc Welding). The arc welding method is to make the electrode and the work object contact and electrify first, and then separate to cause the arc. The heat of the arc causes the electrodes to melt and accumulate at the weld. In this method, flux needs to be added during the welding process, such as on the electrode, to avoid the direct oxidation reaction between the high-temperature molten metal and the active gas in the atmosphere. When melting at high temperature, the flux forms slag floating on the surface of the weld bead to protect the metal material to be welded. After the welding is solidified and cooled, the flux turns into glassy welding slag, which can be removed by scraping and grinding. These welding slags Become the main waste of welding industry.

According to the pollution sources listed by the Environmental Protection Agency of the Executive Yuan, Taiwan produces an average of about 750 tons of submerged arc welding slag and 220 tons of non-submerged arc welding slag every year. If it is non-submerged arc welding slag, it is mostly disposed of by landfill.

However, due to the high cost of the related technology of remanufacturing submerged arc welding slag into welding flux, its application ratio is generally limited. In addition, the way of burial is usually sealed by cement, but the chemical composition of welding slag is mainly composed of calcium oxide, magnesium oxide, silicon dioxide, aluminum oxide, sulfide and manganese oxide, among which free calcium oxide, free Magnesium oxide, manganese sulfide formed by combining with sulfide and manganese oxide, may cause volume expansion when interacting with water, causing cracking or even destruction of sealed concrete, which will cause doubts about durability and environmental compatibility.

In order to solve the problems faced by the prior art, a manufacturing method for recycling a large amount of welding slag, meeting economic benefits, and regenerating it into an inorganic cementitious material is provided here.

The manufacturing method of the inorganic bonding material comprises a raw material preparation step, a mixing step, a curing step and a drying step. The raw material preparation step is to provide a powder mixture including welding slag powder and glass powder. The welding slag powder accounts for 5wt% to 50wt% in the powder mixture, and the glass powder accounts for 50wt% to 95wt%. The welding slag powder contains 18wt% to 30wt% SiO ₂ and 10wt% to 20wt% Al ₂ O ₃ , and the glass powder contains more than 85wt% SiO ₂ .

The mixing step is to place the powder mixture in a mixing tank, and add an alkali activator in the mixing tank for mixing and reaction to form a mixing slurry, wherein the alkali equivalent of the mixing slurry is 2% to 9 %, the water-binder ratio is 0.25 to 0.4.

The curing step is to place the mixed slurry in a curing environment for curing time to obtain a cemented body, wherein the temperature of the curing environment is 60 to 80 degrees Celsius, and the curing time is at least 16 hours. The drying step is to dry the cemented body. The definition of alkali equivalent is shown in equation (1), and the definition of water-binder ratio is shown in equation (2).

。 Equation (1): Alkali equivalent =

.

。 Equation (2): Water-binder ratio =

.

In some embodiments, the base activator is NaOH.

In some embodiments, the alkali activator is added into the mixing tank at a temperature of 60 to 90 degrees Celsius, and the mixing time of the alkali activator and the powder mixture is 10 to 30 minutes. In more detail, in some embodiments, the alkali activator is added into the mixing tank at a temperature of 80 degrees Celsius, and the alkali activator is mixed with the powder mixture for 15 minutes.

In some embodiments, the specific surface area of the welding slag powder ranges from 1900 to 2600 cm ² /g, and the specific surface area of the glass powder ranges from 3500 to 5000 cm ² /g.

In some embodiments, the welding slag powder further includes 30wt% to 48wt% CaO and 12wt% to 18wt% MgO.

In some embodiments, the glass powder also includes 9 wt % to 15 wt % CaO.

In some embodiments, the welding slag powder comprises 25 wt% to 35 wt% of the powder mixture.

In some embodiments, the source of the glass powder is selected from the group consisting of general glass, electronic grade glass fiber, and glass substrate.

A cured inorganic binder is provided here, which is formed by the manufacturing method of the inorganic binder in the foregoing embodiments.

As shown in the previous examples, the calcium-silicate vitreous minerals in the welding slag powder and the glass powder are dissolved through the alkali activator, and the silicon-aluminum ions in the slurry are dehydrated to carry out polycondensation reaction, and the solidification of the silicon-aluminum inorganic solidification is achieved. thing. Through sufficient curing time, its volume can be stable, and it has the characteristics of cementation. It can be applied to the application of mortar preparation, and achieves the effect of low cost and large amount of recycling, which helps to reduce the problems caused by burial, and can be recycled. Reduce the impact on the environment.

FIG. 1 is a flowchart of a method for producing an inorganic binder. As shown in FIG. 1 , the manufacturing method S1 of the inorganic binder includes a raw material preparation step S10 , a mixing step S20 , a curing step S30 and a drying step S40 . The raw material preparation step S10 is to provide a powder mixture of welding slag powder and glass powder. The welding slag powder accounts for 5wt% to 50wt% in the powder mixture, and the glass powder accounts for 50wt% to 95wt%. Here, it should be noted that the weight percentage of welding slag is also called "slag replacement rate" in the industry. For example, 33wt% of welding slag powder is also called 33% welding slag replacement rate.

Here, the source of the glass powder is one or more of common glass, electronic grade glass fiber or glass substrate. The main source of general glass, electronic grade glass fiber or glass substrate is recycled glass product scrap. Weld slag comes from vitreous waste scraped off after welding. They were crushed into powder respectively.

Since the welding slag this time can be submerged arc welding slag or non-submerged arc welding slag, its components are widely distributed, and each batch of welding slag may have different components. According to the formula of general welding flux, it is estimated that the welding slag powder contains 18wt% to 30wt% SiO ₂ and 10wt% to 20wt% Al ₂ O ₃ , and the glass powder contains more than 85wt% SiO ₂ . The binder mainly makes aluminum and silicon ions undergo polycondensation reaction. Compared with the large difference in the composition of the welding slag each time, the composition of the glass powder is relatively stable. In actual operation, the composition ratio of the welding slag can be measured first, and the ratio of the glass powder can be adjusted according to the composition ratio of the welding slag. More commonly, the weld slag powder comprises 25 wt% to 35 wt%.

More specifically, the specific surface area of the pulverized welding slag powder ranges from 1900 to 2600 cm ² /g, and the specific surface area of the glass powder ranges from 3500 to 5000 cm ² /g. In this way, the surface area of the powder mixture is increased to increase the rate of reaction.

In the mixing step S20, the powder mixture is placed in a mixing tank, and an alkali activator is added in the mixing tank for mixing and reaction to form a mixing slurry. Here, the alkali activator is NaOH for cost-effectiveness, but KOH or other lyes can be used instead. In the mixing slurry, the alkali activator can be formulated according to the composition of the welding slag powder, the required strength of the cemented body of the final product, and the set alkali equivalent and water-binder ratio. In some embodiments, the alkali equivalent is 2% to 9%, and the water-binder ratio is 0.25 to 0.4. Here, the definition of alkali equivalent is shown in equation (1), and the definition of water-binder ratio is shown in equation (2).

。 Equation (1): Alkali Equivalent (AE) =

.

。 Equation (2): Water-binder ratio (W/B)=

.

The curing step S30 is to place the mixed slurry in a curing environment for a curing time to obtain a cemented body, wherein the temperature of the curing environment is 60 to 80 degrees Celsius, and the curing time is at least 16 hours. Here, a curing environment is provided, so that in the welding slag powder, CaO, MgO, MnO, MnS, etc. that may cause volume expansion react first, so that the volume of the cemented body expands first in the state of mixing the slurry, and then the mixing slurry The silicon-aluminum ion in the body is dehydrated for polycondensation reaction, and the silicon-aluminum inorganic polymer is solidified, and the volume of the cemented body can be stabilized.

The chemical reactions generated in the mixing step S20 and the curing step S30 will be described in detail below. Generally speaking, _SiO2 in welding slag powder and glass powder reacts with NaOH, which will destroy the original glassy O-Si-O bond, and produce a dissociation reaction, which is called alkali excitation. The reaction formula is as follows Formula (1) shown. In fact, since the composition of the welding slag may be different each time, the alkalinity of the welding slag powder itself will be considered to adjust the added alkali activator and set the alkali equivalent for the reaction to occur.

。 Reaction formula (1):

.

及

與水持續發生反應，將生成Si(OH) ₄，如反應式(2)及反應式(3)所示。 Next, dissociated siloxane monomer anions, such as

and

Continuous reaction with water will generate Si(OH) ₄ , as shown in reaction formula (2) and reaction formula (3).

。 Reaction formula (2):

.

。 Reaction formula (3):

.

Next, Si(OH) ₄ reacts continuously with NaOH to form a silicate monomer, as shown in equation (4).

。 Reaction formula (4):

.

When the reaction continues, so that the concentration of silicate monomer in the mixing slurry continues to increase, polycondensation reaction may occur to form silicate dimer, as shown in the reaction formula (5), and continue to react with other silicic acid The salt monomer undergoes a polymerization reaction to further form a siloxane framework structure.

。 Reaction formula (5):

.

In the reaction formula, part of silicon will be replaced by aluminum to form a silicon-aluminum-oxygen framework structure. In addition, the welding slag powder also contains 30wt% to 48wt% of CaO, 12wt% to 18wt% of MgO, and a small amount of MnO and SO ₃ . The glass powder also contains 9wt% to 15wt% CaO. In the mixing stage, the alkali activator is usually added into the mixing tank at a high temperature of 60 to 90 degrees Celsius, and the alkali activator is mixed with the powder mixture for 10 to 30 minutes. In this way, in order to accelerate the reaction of these components, the volume is pre-expanded, and after the reaction forms a silicon-aluminum-oxygen framework structure, calcium, magnesium, manganese, sulfur and other ions will be fixed on the framework structure without separation. Oxide, after a sufficient curing time, a stable volume of cement is obtained.

The drying step S40 is to dry the cemented body. Here, the excess water can be removed by standing, drying, air-drying, etc., and the cured inorganic binder can be obtained. When it needs to be used in practice, water can be added to replace cement, and it can be mixed with sand to form mortar.

Hereinafter, the manufacturing method of the inorganic binder will be described with practical examples.

Firstly, a batch of welding slag was obtained from the welding factory, and after powderization, XRF was used for component analysis, and the obtained component weight percentages are shown in Table 1 below. Table 1 ingredients CaO SiO ₂ MgO Al ₂ O ₃ SO _{3 Fe2O3 _} TiO ₂ MnO Cr ₂ O ₃ Wt( %) 44.88 24.82 15.82 11.01 2.1 0.8 0.26 0.21 0.015

Here, the glass powder obtained from the waste glass recycling plant is used together. After XRF analysis, the composition of the waste glass powder is shown in Table 2 below. Table 2 ingredients CaO SiO ₂ Al ₂ O _{3 Fe2O3 _} K ₂ O Wt (%) 11.15 87.36 0.25 0.27 0.63

The powder mixture is formulated with 33wt% of welding slag powder and 67wt% of glass powder.

In Example 1, in the mixing step S20, NaOH was added under the conditions of alkali equivalent of 6% and water-binder ratio of 0.3, NaOH was added to the powder mixture at room temperature at 80 degrees Celsius, and the mixing temperature was maintained at Celsius 80 degrees, the alkali activator and the powder mixture are mixed for 15 minutes to carry out mixing and reaction.

Next, in the curing step S30 , curing is carried out at 80 degrees Celsius for 24 hours. Finally, the inorganic binder that has passed through the drying step S40 is cured. No volume expansion was confirmed after 7 days, and the compressive strength test was carried out after 7 days and 28 days. The compressive strength was 25 MPa after 7 days, and increased slightly after 28 days. In this way, it exceeds the compressive strength of ordinary cement.

Example 2 is the same as in Example 1. Adjust the alkali equivalent to 8%. After 7 days, it is confirmed that there is no volume expansion. The compressive strength test is carried out with multiple sets of test pieces. The measurement results show that the compressive strength is between 13 and 20 MPa .

Example 3 Adjust the proportion of welding slag powder to 50wt%, and the alkali equivalent to 8%. After 7 days, it is confirmed that there is no volume expansion, and the compressive strength test is carried out with multiple test pieces. The compressive strength of the measurement results is between 10 and 15 MPa. between.

Figures 2 to 4 are line graphs of actual experiments. To present the results of actual experiments of other groups of embodiments. Figure 2 is based on the composition ratio and curing conditions of Example 1, only for the adjustment of the mixing temperature to determine the impact on the compressive strength. Figure 3 is to fix the mixing conditions and curing conditions, change the alkali equivalent and composition to judge the impact on the compressive strength. Figure 4 shows the fixed components, changing the alkali equivalent and water-binder ratio to judge the impact on the compressive strength.

In this way, the water-binder ratio, alkali equivalent, or mixing temperature can be adjusted according to the compressive strength required for different purposes, so as to obtain the cured inorganic binder with the required strength. In these experiments, the reasonably estimated ranges of ingredients, water-binder ratio, alkali equivalent, mixing conditions, and curing conditions are as mentioned above.

To sum up, the calcium-silicate-aluminum vitreous minerals in the welding slag powder and glass powder are dissolved through the alkali activator, and the silicon-aluminum ions in the slurry are dehydrated for polycondensation reaction, and hardened into a silicon-aluminum inorganic cured product. Through adequate curing time, its volume can be stabilized, and it has the characteristics of cementation. It can be applied to the deployment of mortar, and achieve the effect of low cost and large amount of recycling, which helps to reduce the problems caused by burial, and can be recycled, effectively minimize the impact on the environment.

Although the technical content of the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any modification and modification made by those skilled in the art without departing from the spirit of the present invention should be covered by the present invention. Therefore, the scope of protection of the present invention should be defined by the scope of the appended patent application.

S1: Manufacturing method of inorganic binder S10: raw material preparation step S20: mixing step S30: Maintenance steps S40: drying step

FIG. 1 is a flowchart of a method for producing an inorganic binder. Figures 2 to 4 are line graphs of actual experiments.

S1: Manufacturing method of inorganic binder

S10: raw material preparation step

S20: mixing step

S30: Maintenance steps

S40: drying step

Claims (10)

A method for manufacturing an inorganic binder, comprising: a raw material preparation step, providing a powder mixture comprising welding slag powder and glass powder, wherein in the powder mixture, the welding slag powder accounts for 5wt% to 50wt%, and the glass powder accounts for 50wt% to 95wt%, wherein the slag powder contains 18wt% to 30wt% SiO ₂ and 10wt% to 20wt% Al ₂ O ₃ , the glass powder contains more than 85wt% SiO ₂ ; a mixing step, The powder mixture is placed in a mixing tank, and an alkali activator is added in the mixing tank for mixing and reaction to form a mixing slurry, wherein the alkali equivalent of the mixing slurry is 2% to 9%, the water-cement ratio is 0.25 to 0.4; a curing step, the mixed slurry is placed in a curing environment for a curing time to obtain a cemented body, wherein the temperature of the curing environment is 60 to 80 degrees Celsius, the The curing time is at least 16 hours; and a drying step to dry the cemented body; wherein the alkali equivalent is defined as equation (1), the water-binder ratio is defined as equation (2), equation (1): alkali equivalent =

; Equation (2): water-binder ratio =

. The method for producing an inorganic binder according to claim 1, wherein the alkali activator is NaOH. The manufacturing method of the inorganic binder as claimed in item 1, wherein the alkali activator is added to the mixing tank at a temperature of 60 to 90 degrees Celsius, and the alkali activator is mixed with the powder mixture for 10 to 10 degrees Celsius. 30 minutes. The manufacturing method of the inorganic binder according to claim 3, wherein the alkali activator is added into the mixing tank at a temperature of 80 degrees Celsius, and the alkali activator is mixed with the powder mixture for 15 minutes. The manufacturing method of the inorganic binder according to claim 1, wherein the specific surface area of the welding slag powder ranges from 1900 to 2600 cm ² /g, and the specific surface area of the glass powder ranges from 3500 to 5000 cm ² /g. The manufacturing method of the inorganic binder according to claim 1, wherein the welding slag powder further contains 30wt% to 48wt% of CaO and 12wt% to 18wt% of MgO. According to the manufacturing method of the inorganic binder described in Claim 1, the glass powder further contains 9wt% to 15wt% of CaO. The manufacturing method of the inorganic binder according to claim 1, wherein in the powder mixture, the welding slag powder accounts for 25wt% to 35wt%. According to the manufacturing method of the inorganic binder described in Claim 1, the source of the glass powder is selected from the group consisting of general glass, electronic grade glass fiber and glass substrate. A cured inorganic binder formed by the manufacturing method of the inorganic binder described in Claims 1 to 9.

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