A method for manufacturing steel slag porous brick

Abstract

The application relates to a solid waste recycling and treatment technical field, and particularly discloses a steel slag porous brick manufacturing method, which comprises the following steps: step one: pouring glue material, water and water reducing agent into a stirring cylinder according to a proportioning ratio, fully stirring until a metal luster appears on a surface of cement paste; step two: adding aggregate accounting for 40%-60% of the total amount for the first time, fully stirring, adding the remaining aggregate for the second time, continuously stirring until the cement paste is uniformly wrapped on the surface of the aggregate to form a cement paste shell on the surface of the aggregate; step three: pouring the mixed slurry into a mold in multiple layers, compacting after removing the excess loose material on the surface; step four: after the mold is filled and shaped, maintaining at room temperature, covering with plastic paper to reduce water evaporation, appropriately spraying water every 5.5-6.5 hours to ensure the humidity of the brick body, and demolding after 1 day; and step five: after the mold is demolded, static maintenance at room temperature for 28 days to obtain the final porous brick. The patent aims to solve the problems of difficult steel slag solid waste treatment, easy cracking of building materials during long-term use and hidden safety hazards.

Description

Technical Field

[0001] This invention relates to the field of metallurgical solid waste recycling and treatment technology, and in particular to a method for manufacturing porous bricks from steel slag. Background Technology

[0002] Steel slag is a solid waste product of the iron and steel metallurgical industry. With the continuous development of the iron and steel industry, the amount of steel slag is also increasing. How to make effective use of it has become one of the problems that the modern iron and steel industry urgently needs to solve.

[0003] Currently, the most widespread resource utilization method for steel slag disposal is its application in the building materials field. However, due to the excessively high content of free calcium oxide (f-CaO) in steel slag, the f-CaO in the slag powder reacts with water to form hydroxides, causing it to expand in volume. During its use, with the increase in service life, its volume can expand several times over, leading to cracking of building structures. Its solid phase volume change can reach more than 100%, affecting the stability of buildings and posing significant safety hazards. Therefore, its application in the building materials field is limited. Untreated steel slag, when simply stockpiled, results in a serious waste of large areas of land. Although steel slag can be used as road filler, its high density and weight lead to high transportation costs, and the low added value of its utilization generally limits construction sites to areas near steel plants.

[0004] Existing research on steel slag solid waste treatment mainly focuses on steel slag modification, but such research is still at the laboratory level, and it is unclear whether industrial-scale production and processing can be achieved. Even if industrial-scale production and processing can be achieved, the pretreatment of steel slag modification will increase the cost of steel slag resource utilization, and will also further increase the processing steps for steel slag solid waste recycling. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the technical problem solved by this invention is to provide a method for manufacturing porous steel slag bricks, thereby solving the problems of difficult treatment of existing steel slag solid waste, easy cracking after long-term use in building materials, and potential safety hazards.

[0006] To solve the above problems, the technical solution adopted by the present invention is: a method for manufacturing porous bricks made of steel slag, comprising the following steps:

[0007] Step 1: Pour the adhesive, water, and water-reducing agent into the mixing drum according to the specified ratio, and stir thoroughly until the cement slurry surface shows a metallic luster; Step 2: Add 40%-60% of the aggregate as the first addition, and stir thoroughly. Add the remaining aggregate as the second addition, and continue stirring until the cement slurry evenly coats the aggregate surface, forming a cement slurry shell on the aggregate surface; Step 3: Pour the mixed slurry into the mold in multiple layers, remove excess loose material from the surface, and compact it; Step 4: After molding, cure at room temperature, cover with plastic film to reduce moisture loss, and spray water appropriately every 5.5-6.5 hours to maintain the humidity of the brick. Remove the mold after 1 day; Step 5: After demolding, cure at room temperature for 28 days to obtain the final porous brick.

[0008] Furthermore, the porous brick solid raw material comprises the following components by mass percentage: 6%-10% adhesive, 90%-94% aggregate, a water-to-binder ratio of 0.25-0.30, and a water-reducing agent added at 1%-2% of the amount of adhesive.

[0009] Furthermore, the adhesive material is composed of ordinary silicate cement, slag, and steel slag powder, with the mass percentage of ordinary silicate cement being 40-50%, the mass percentage of slag being 25-30%, and the mass percentage of steel slag powder being 25-30%.

[0010] Furthermore, the steel slag powder with a particle size distribution percentage of 50% or less has a particle size of 5 μm or less, and the steel slag powder with a particle size distribution percentage of 90% or more has a particle size of 15 μm or less.

[0011] Furthermore, the aggregate includes coarse aggregate, medium aggregate and fine aggregate, with the coarse aggregate having a particle size range of 15mm-20mm, the medium aggregate having a particle size range of 10mm-15mm, and the fine aggregate having a particle size range of 2mm-5mm.

[0012] Furthermore, the coarse aggregate and medium aggregate are composed of one or more of natural crushed stone, machine-made crushed stone, ceramsite, and construction waste, and the fine aggregate is steel particles.

[0013] Furthermore, the three aggregates are mixed evenly in a 1:1:1 ratio before being added.

[0014] Furthermore, the mixing time in step one is 2-5 minutes, and the mixing time after the first addition of aggregate in step two is 3-5 minutes, and the mixing time after the second addition of aggregate is 3-5 minutes.

[0015] The technical principle behind this solution is as follows: Under the corresponding particle size range and reference conditions, the free calcium oxide within the steel slag powder can fully contact water during the initial production of porous bricks, resulting in a relatively complete hydration reaction in the early stages. The volume change is essentially completed in the early stages of stable brick formation. Even if unreacted f-CaO remains in the later stages of porous brick use, the resulting volume change is minimal and will not cause any change in brick volume. Simultaneously, under the corresponding particle size range and reference conditions, when f-CaO expansion occurs subsequently, the porous and multi-cavity structure of the brick itself provides space for the volume change after the f-CaO hydration reaction, preventing other structures within the brick from being compressed and deformed, thus avoiding damage to the brick structure.

[0016] The beneficial effects of this method are as follows: using steel slag as aggregate to prepare porous bricks, due to its inherent hardness, can improve the strength of the bricks. Furthermore, through the raw material ratio and size limitations of this method, a more complete hydration reaction of free calcium oxide can be achieved during the production process of porous bricks, thereby reducing the content of undigested free calcium oxide. Simultaneously, the porous brick structure provides sufficient space to accommodate the expansion of free calcium oxide later, ensuring the overall structural stability of the bricks. After curing for 28 days, the porous bricks showed no significant expansion or cracking when boiled for 1 hour or autoclaved for 1 hour. Testing according to GB2579-2010 "Porous Bricks for Load-Bearing Concrete" showed a porosity ≥25% and a strength grade reaching MU15. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the manufacturing process of the porous steel slag bricks of this invention. Detailed Implementation

[0018] The following detailed description illustrates the specific implementation method:

[0019] Example 1 is as attached. Figure 1 As shown:

[0020] The solid raw materials for steel slag porous bricks consist of the following components by mass percentage: 6% binder, 94% aggregate, a water-to-binder ratio of 0.25, and a water-reducing agent added at 1% of the binder content. The binder is composed of ordinary Portland cement, slag, and steel slag powder, with ordinary Portland cement comprising 40% by mass, slag 30%, and steel slag powder 30%. The aggregate includes coarse, medium, and fine aggregates. The coarse aggregate has a particle size range of 15mm-20mm, the medium aggregate 10mm-15mm, and the fine aggregate 2mm-5mm, with a ratio of 1:1:1. The coarse and medium aggregates consist of natural crushed stone, machine-made crushed stone, ceramsite, and construction waste, while the fine aggregate is steel particles crushed from steel slag. In the steel slag powder, 50% of the particles have a particle size distribution of less than or equal to 5μm, and 90% have a particle size distribution of less than or equal to 15μm.

[0021] Porous bricks made from steel slag are prepared through the following steps:

[0022] Step 1: Pour the adhesive, water and water-reducing agent into the mixing drum according to the ratio, and stir thoroughly for 3 minutes until the surface of the cement paste shows a metallic luster;

[0023] Step 2: Add 50% of the total aggregate for the first time and mix thoroughly for 3 minutes. Add the remaining aggregate for the second time and continue mixing for 4 minutes until the cement slurry evenly coats the surface of the aggregate and forms a cement slurry shell on the surface of the aggregate.

[0024] Step 3: Pour the mixed slurry into the mold in multiple layers, remove excess loose material from the surface, and then compact it;

[0025] Step 4: After molding, cure at room temperature, cover with plastic sheeting to reduce moisture loss, spray with water every 6 hours to maintain the humidity of the bricks, and remove the mold after 24 hours.

[0026] Step 5: After demolding, allow the brick to cure at room temperature for 28 days to obtain the final porous brick.

[0027] The parts of Example 2 that are the same as those in Example 1 will not be repeated. The difference is that the solid raw material for the steel slag porous brick includes the following components by mass percentage: 10% binder, 90% aggregate, water-binder ratio of 0.30, and water-reducing agent added at 2% of the binder content. The binder consists of ordinary silicate cement, slag, and steel slag powder, with ordinary silicate cement accounting for 50% by mass, slag for 25% by mass, and steel slag powder for 25% by mass. The aggregate includes coarse aggregate, medium aggregate, and fine aggregate. The coarse aggregate has a particle size range of 15mm-20mm, the medium aggregate has a particle size range of 10mm-15mm, and the fine aggregate has a particle size range of 2mm-5mm. The ratio of the three aggregates is 1:1:1. The coarse and medium aggregates consist of natural crushed stone, machine-made crushed stone, ceramsite, and construction waste, while the fine aggregate is steel pellets. In steel slag powder, the particle size distribution percentage of 50% is less than or equal to 5μm, and the particle size distribution percentage of 90% is less than or equal to 15μm.

[0028] Comparative Example 1: The difference from Example 1 is that the ratio of coarse aggregate, medium aggregate and fine aggregate is 1:1:2;

[0029] Comparative Example 2: The difference from Example 1 is that the particle size of the fine aggregate is in the range of 5mm-10mm;

[0030] Comparative Example 3: The difference from Example 1 is that the coarse aggregate has a particle size range of 10mm-15mm and the medium aggregate has a particle size range of 5mm-10mm.

[0031] Comparative Example 4: The difference from Example 1 is that the steel slag powder with a particle size distribution percentage of 50% is less than or equal to 20 μm, and the steel slag powder with a particle size distribution percentage of 90% is less than or equal to 100 μm.

[0032] The porous bricks prepared in Examples 1, 2, and Comparative Examples 1-4 were subjected to a 1-hour pressure boiling test. The test results are shown in the table below:

[0033]

[0034] Based on the experimental results in the table above, in Examples 1 and 2 of this scheme, the bricks did not crack or deform after steaming and remained in normal condition; while the bricks in Comparative Examples 1-3 cracked significantly, and the bricks in Comparative Example 4 deformed significantly.

[0035] The bricks of Examples 1 and 2 were tested according to GB25779-2010 "Porous Bricks for Load-Bearing Concrete". The porosity of the porous bricks produced in Examples 1 and 2 was ≥25%, and the strength grade reached MU15, which met the national standard requirements for porous bricks for load-bearing concrete.

[0036] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for manufacturing porous bricks from steel slag, characterized in that: Includes the following steps: Step 1: Pour the adhesive, water, and water-reducing agent into the mixing drum according to the specified ratio, and stir thoroughly until the surface of the cement slurry shows a metallic luster; the adhesive is composed of ordinary Portland cement, slag, and steel slag powder, with the mass percentage of ordinary Portland cement being 40-50%, the mass percentage of slag being 25-30%, and the mass percentage of steel slag powder being 25-30%; the steel slag powder with a particle size distribution percentage of 50% or more has a particle size of less than or equal to 5μm, and the steel slag powder with a particle size distribution percentage of 90% or more has a particle size of less than or equal to 15μm; Step 2: Add 40%-60% of the total aggregate for the first time and mix thoroughly. Add the remaining aggregate for the second time and continue mixing until the cement slurry evenly coats the surface of the aggregate and forms a cement slurry shell on the surface of the aggregate. The aggregates include coarse aggregates, medium aggregates, and fine aggregates. The coarse aggregates have a particle size range of 15mm-20mm, the medium aggregates have a particle size range of 10mm-15mm, and the fine aggregates have a particle size range of 2mm-5mm. The three types of aggregates are mixed evenly in a mass ratio of 1:1:1 before being added to the aggregates. The coarse and medium aggregates are composed of one or more of the following: natural crushed stone, machine-made crushed stone, ceramsite, and construction waste. The fine aggregates are steel particles made from crushed steel slag. Step 3: Pour the mixed slurry into the mold in multiple layers, remove excess loose material from the surface, and then compact it; Step 4: After molding, cure at room temperature, cover with plastic sheeting to reduce moisture loss, spray water appropriately every 5.5-6.5 hours to maintain the humidity of the bricks, and remove the mold after 24-26 hours of curing. Step 5: After demolding, allow the brick to cure at room temperature for 28-30 days to obtain the final porous brick.

2. The method for manufacturing porous steel slag bricks according to claim 1, characterized in that: The solid raw materials of porous bricks consist of the following components by mass percentage: 6%-10% adhesive, 90%-94% aggregate, water-to-binder ratio of 0.25-0.30, and water-reducing agent added at 1%-2% of the amount of adhesive.

3. The method for manufacturing porous steel slag bricks according to claim 1, characterized in that: The mixing time in step one is 2-5 minutes. In step two, the mixing time is 3-5 minutes after the first addition of aggregate and 3-5 minutes after the second addition of aggregate.

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