Method for preparing light self-foaming ceramsite by using steel enterprise solid waste

Abstract

The invention relates to the technical field of preparation of environment-friendly materials, in particular to a method for preparing light self-foaming ceramsite from solid waste of a steel enterprise. Comprising the following steps: 1) burdening: dry-mixing and uniformly mixing raw materials including steel enterprise solid waste, an alkali activator, citric acid and AlCl3; 2) granulation: adding a water glass aqueous solution into the uniformly mixed raw materials, uniformly stirring, and granulating to obtain a ceramsite raw material; 3) steam curing: putting the ceramsite raw material into a steam curing pot filled with ethylene glycol, and carrying out steam curing treatment; and 4) aging: carrying out drying treatment on the ceramsite subjected to steam curing, so as to obtain the light self-foaming ceramsite. The lightweight self-foaming ceramsite with multiple pores and uniform foaming is prepared by adopting an in-situ foaming method, so that the problem of stability of an air entraining agent generally existing in preparation of the unfired lightweight ceramsite at present can be solved, and positive contributions can be made to resource utilization of solid wastes in steel enterprises and ecological environment protection; and a new effective way is provided for the treatment of solid wastes in steel enterprises.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of environmental protection materials, and particularly to a method for preparing lightweight self-foaming ceramsite by using solid waste from steel enterprises. Background Art

[0002] Solid waste from iron and steel enterprises, including by-products in the processes of mining and smelting, has long been one of the important sources of environmental pollution. Therefore, how to achieve efficient treatment and resource utilization of solid waste from steel enterprises has become an urgent problem to be solved, which is related to the sustainable development of the ecological environment and the sustainability of human society.

[0003] In recent years, relatively remarkable results have been achieved in the recycling of solid waste from steel enterprises, such as using the solid waste as backfill materials for mining areas or for preparing ceramsite. Ceramsite is a lightweight and porous building material with properties such as heat preservation and environmental protection, and is widely used in fields such as construction, horticulture, and water treatment, and is an important green building material. However, although the research on preparing sintered ceramsite from solid waste of steel enterprises is very common, the research on preparing non-fired lightweight ceramsite from solid waste of steel enterprises is relatively less.

[0004] At present, aluminum powder and hydrogen peroxide are often used as foaming agents for non-fired ceramsite. For example, in the Chinese patent application with the publication number CN106007434A, "A kind of alkali-activated high-titanium slag non-fired ceramsite and its preparation method", aluminum powder or / and hydrogen peroxide is used as a pore-forming agent. However, this approach has some problems, and the most important problem is the instability and easy decomposition of the foaming agent, resulting in extremely difficult storage of raw materials and the preparation process of ceramsite.

[0005] In contrast, the present invention provides a new idea and solution to solve the above problems. Compared with the prior art, the present invention has multiple advantages: First, the foaming particle size is good, and high-quality ceramsite can be obtained; second, the foaming yield is high, and the production efficiency can be greatly improved; at the same time, the method of the present invention has no environmental pollution and meets the requirements of green production; in addition, the raw materials used in the present invention have good storage properties, and the storage conditions can be reduced; and most importantly, in an extreme environment, the self-foaming ceramsite prepared by the present invention has good use stability. Summary of the Invention

[0006] The present invention provides a method for preparing lightweight self-foaming ceramsite by using solid waste from steel enterprises. By using the in-situ foaming method, lightweight self-foaming ceramsite with many pores and uniform foaming is prepared. It can not only solve the problem of the stability of the foaming agent commonly existing in the preparation of current non-fired lightweight ceramsite, but also make a positive contribution to the resource utilization of solid waste from steel enterprises and ecological environment protection, and provides a new and effective way for the treatment of solid waste from steel enterprises.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for preparing lightweight self-foaming ceramsite using solid waste from steel enterprises, comprising the following steps:

[0009] 1) Batching: dry-mix the raw materials including steel enterprise solid waste, alkali activator, citric acid and AlCl3;

[0010] 2) Granulation: adding water glass aqueous solution to the mixed raw materials, stirring evenly and then granulating to obtain ceramsite raw material;

[0011] 3) Steaming: Place the ceramsite raw material at room temperature for 10 to 14 hours, then put it into a steaming pot filled with ethylene glycol, and steam-cure it at a temperature of 100 to 230°C and a pressure of 0.1 to 2.7 MPa;

[0012] 4) Aging: The steam-cured ceramsite is dried at a temperature of 80-110° C. to obtain lightweight self-foaming ceramsite.

[0013] In the step 1), the composition of the raw materials is calculated by weight as follows: 70-120 parts of steel enterprise solid waste; 0-20 parts of alkaline activator; 0-5 parts of citric acid; and 1-3 parts of AlCl3.

[0014] The alkali activator is one or more of water glass, sodium hydroxide, cement and quicklime.

[0015] The steel enterprise solid waste is one or more of iron tailings, steel tailings, and plate and frame mud; the chemical composition includes SiO2 75% to 90%, TFe 10% to 25%; and the particle size is ≤3mm.

[0016] In the step 1), the raw materials are dry mixed in a disc granulator.

[0017] In the step 2), the amount of water glass aqueous solution added is 4% to 8% of the total mass of the raw materials, and the modulus of the water glass aqueous solution is 1.9 to 3.1.

[0018] The prepared lightweight self-foaming ceramsite has a bulk density of ≤900kg / m 3 ; Cylinder pressure strength ≥4MPa; 1h water absorption ≤5%; Porosity ≥50%.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1) The present invention adopts an in-situ foaming method to prepare lightweight self-foaming ceramsite using solid waste from steel enterprises. Under stable process conditions, a lightweight self-foaming ceramsite with many pores and uniform foaming can be obtained, which is suitable for industrial large-scale production.

[0021] 2) The present invention adopts a simple steaming process to obtain lightweight porous ceramsite with a porosity greater than 30% and a compressive strength greater than 2MPa, and the preparation process is simple and efficient.

[0022] 3) The present invention can control the porosity and cylinder pressure strength of lightweight ceramsite by adjusting the concentration of the air entraining agent, and the product performance can be adjusted conveniently and flexibly.

[0023] 4) The preparation of lightweight self-foaming expanded clay adopts a low-temperature reaction foaming process, which has a wide range of applications and requires low preparation conditions. DETAILED DESCRIPTION

[0024] The method for preparing lightweight self-foaming ceramsite by using solid waste from steel enterprises described in the present invention comprises the following steps:

[0025] 1) Batching: dry-mix the raw materials including steel enterprise solid waste, alkali activator, citric acid and AlCl3;

[0026] 2) Granulation: adding water glass aqueous solution to the mixed raw materials, stirring evenly and then granulating to obtain ceramsite raw material;

[0027] 3) Steaming: Place the ceramsite raw material at room temperature for 10 to 14 hours, then put it into a steaming pot filled with ethylene glycol, and steam-cure it at a temperature of 100 to 230°C and a pressure of 0.1 to 2.7 MPa;

[0028] 4) Aging: The steam-cured ceramsite is dried at a temperature of 80-110° C. to obtain lightweight self-foaming ceramsite.

[0029] In the step 1), the composition of the raw materials is calculated by weight as follows: 70-120 parts of steel enterprise solid waste; 0-20 parts of alkaline activator; 0-5 parts of citric acid; and 1-3 parts of AlCl3.

[0030] The alkali activator is one or more of water glass, sodium hydroxide, cement and quicklime.

[0031] The steel enterprise solid waste is one or more of iron tailings, steel tailings, and plate and frame mud; the chemical composition includes SiO2 75% to 90%, TFe 10% to 25%; and the particle size is ≤3mm.

[0032] In the step 1), the raw materials are dry mixed in a disc granulator.

[0033] In the step 2), the amount of water glass aqueous solution added is 4% to 8% of the total mass of the raw materials, and the modulus of the water glass aqueous solution is 1.9 to 3.1.

[0034] The prepared lightweight self-foaming ceramsite has a bulk density of ≤900kg / m 3; cylinder compressive strength ≥ 4 MPa; 1-hour water absorption ≤ 5%; porosity ≥ 50%.

[0035] The method for preparing lightweight self-foaming ceramsite using steel enterprise solid waste according to the present invention has the following principle: A mixed solution of citric acid, AlCl3, and ethylene glycol is used as a foaming agent. When the three substances are mixed, an oxidation-reduction reaction occurs under alkaline environment, high temperature, and high pressure conditions: ethylene glycol reduces Al 3+ to elemental Al; citric acid reacts with Fe2O3 in the steel enterprise solid waste to reduce Fe 3 + to Fe 2+ or elemental Fe; elemental Al / Fe reacts with calcium silicate hydrate (C-S-H gel) or unreacted CaO, SiO2 in the ceramsite under humid and hot conditions to generate H2, CO2, and a small amount of CH4 gas, achieving the purpose of self-foaming and pore formation.

[0036] To more intuitively illustrate the present invention, the implementation manner of the present invention will be further described in combination with examples. The following examples are only preferred specific implementation manners of the present invention, but the protection scope of the present invention is not limited thereto. Any technical solutions that can be obviously obtained by those skilled in the art within the technical scope disclosed by the present invention, including simple changes or equivalent replacements, are within the protection scope of the present invention.

[0037]

Example 1

[0038] The process for preparing lightweight self-foaming ceramsite using steel enterprise solid waste in this example is as follows:

[0039] 1. Batching: Weigh 90 parts of steel enterprise solid waste, 10 parts of alkali activator, 2.5 parts of citric acid, and 3 parts of AlCl3 as raw materials, and add them to a disk granulator for dry mixing and homogenization. Among them, the steel enterprise solid waste is iron tailings, and the alkali activator is water glass.

[0040] 2. Granulation: Add a water glass aqueous solution with a modulus of 2.2 and accounting for 5% of the raw material mass to the homogenized raw materials, stir evenly and then granulate to obtain green ceramsite.

[0041] 3. Steam curing: Place the green ceramsite at room temperature for 12 h, then put it into a steam curing kettle filled with ethylene glycol, and carry out steam curing treatment at a temperature of 150 °C and a pressure of 0.5 MPa.

[0042] 4. Aging: Dry the steam-cured ceramsite at a temperature of 100 °C to obtain the lightweight self-foaming ceramsite.

[0043]

Example 2

[0044] The process for preparing lightweight self-foaming ceramsite using steel enterprise solid waste in this example is as follows:

[0045] 1. Ingredients: Weigh 100 parts of steel enterprise solid waste, 12 parts of alkali activator, 3 parts of citric acid, and 1 part of AlCl3 as raw materials, add them to a disc granulator, and mix them evenly by dry mixing. Among them, the steel enterprise solid waste is steel tailings, and the alkali activator is water glass.

[0046] 2. Granulation: Add an aqueous solution of water glass with a modulus of 3.1 and accounting for 7% of the raw material mass to the mixed raw materials, stir evenly and then granulate to obtain the ceramsite green stock.

[0047] 3. Steam curing: Place the ceramsite green stock at room temperature for 12 h, then put it into a steam curing kettle filled with ethylene glycol, and carry out steam curing treatment at a temperature of 180 °C and a pressure of 1.17 MPa.

[0048] 4. Aging: Dry the steam-cured ceramsite at a temperature of 100 °C to obtain the lightweight self-foaming ceramsite.

[0049]

Example 3

[0050] The process of preparing lightweight self-foaming ceramsite using steel enterprise solid waste in this example is as follows:

[0051] 1. Ingredients: Weigh 115 parts of steel enterprise solid waste, 15 parts of alkali activator, 4 parts of citric acid, and 3 parts of AlCl3 as raw materials, add them to a disc granulator, and mix them evenly by dry mixing. Among them, the steel enterprise solid waste is iron tailings, and the alkali activator is water glass.

[0052] 2. Granulation: Add an aqueous solution of water glass with a modulus of 3.1 and accounting for 8% of the raw material mass to the mixed raw materials, stir evenly and then granulate to obtain the ceramsite green stock.

[0053] 3. Steam curing: Place the ceramsite green stock at room temperature for 12 h, then put it into a steam curing kettle filled with ethylene glycol, and carry out steam curing treatment at a temperature of 230 °C and a pressure of 2.7 MPa.

[0054] 4. Aging: Dry the steam-cured ceramsite at a temperature of 110 °C to obtain the lightweight self-foaming ceramsite.

[0055]

Example 4

[0056] The process of preparing lightweight self-foaming ceramsite using steel enterprise solid waste in this example is as follows:

[0057] 1. Ingredients: Weigh 120 parts of steel enterprise solid waste, 17 parts of alkali activator, 5 parts of citric acid, and 3 parts of AlCl3 as raw materials, add them to a disc granulator, and mix them evenly by dry mixing. Among them, the steel enterprise solid waste is plate frame mud, and the alkali activator is water glass.

[0058] 2. Pelletizing: Add an aqueous sodium silicate solution with a modulus of 3.1 and accounting for 8% of the raw material mass to the mixed raw materials. After stirring evenly, pelletize to obtain the green pellets of ceramsite.

[0059] 3. Steam curing: Place the green pellets of ceramsite at room temperature for 12 h, and then put them into a steam curing kettle filled with ethylene glycol. Carry out steam curing treatment at a temperature of 180 °C and a pressure of 1.6 MPa.

[0060] 4. Aging: Dry the steam-cured ceramsite at a temperature of 110 °C to obtain the lightweight self-foaming ceramsite.

[0061] Upon inspection, the lightweight self-foaming ceramsite prepared in Examples 1-4 all meet the following performance requirements: bulk density ≤ 900 kg / m 3 ; cylinder compressive strength ≥ 4 MPa; 1 h water absorption rate ≤ 5%; porosity ≥ 50%.

[0062] As mentioned above, it is only the preferred specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A method for preparing lightweight self-foaming ceramsite using solid waste from steel enterprises, characterized in that, It includes the following steps: 1) Batching: Dry-mix and homogenize the raw materials including steel enterprise solid waste, alkali activator, citric acid and AlCl3; 2) Pelletizing: Add an aqueous sodium silicate solution to the homogenized raw materials, stir evenly and then pelletize to obtain the green pellets of ceramsite; 3) Steam curing: Place the green pellets of ceramsite at room temperature for 10 - 14 h, then put them into a steam curing kettle filled with ethylene glycol, and carry out steam curing treatment at a temperature of 100 - 230 °C and a pressure of 0.1 - 2.7 MPa; 4) Aging: Dry the steam-cured ceramsite at a temperature of 80 - 110 °C to obtain the lightweight self-foaming ceramsite.

2. The method for preparing lightweight self-foaming ceramsite using solid waste from steel enterprises according to claim 1, wherein In the step 1), the composition of the raw materials is calculated by mass fraction as follows: steel enterprise solid waste, 70 - 120 parts; alkali activator, 0 - 20 parts; citric acid, 0 - 5 parts; AlCl3, 1 - 3 parts.

3. A method for preparing lightweight self-foaming ceramsite using solid waste from steel enterprises according to claim 1 or 2, characterized in that The alkali activator is one or more of sodium silicate, sodium hydroxide, cement and quicklime.

4. A method for preparing lightweight self-foaming ceramsite using steel enterprise solid waste according to claim 1 or 2, characterized in that, The steel enterprise solid waste is one or more of iron tailings, steel tailings slag and plate frame mud; the chemical composition contains 75% - 90% of SiO2 and 10% - 25% of TFe; the particle size is ≤ 3 mm.

5. A method for preparing lightweight self-foaming ceramsite using solid waste from steel enterprises according to claim 1, characterized in that, In the step 1), the raw materials are dry-mixed in a disk pelletizer.

6. A method for preparing lightweight self-foaming ceramsite using solid waste from steel enterprises according to claim 1, characterized in that, In the step 2), the addition amount of the aqueous sodium silicate solution is 4% - 8% of the total mass of the raw materials, and the modulus of the aqueous sodium silicate solution is 1.9 - 3.

1.

7. A method for preparing lightweight self-foaming ceramsite using solid waste from steel enterprises according to claim 1, characterized in that, The bulk density of the prepared lightweight self-foaming ceramsite is ≤ 900 kg / m 3 ; the cylinder compressive strength is ≥ 4 MPa; the 1-hour water absorption rate is ≤ 5%; the porosity is ≥ 50%.