A material production process to replace primary fly ash

Abstract

A material production process to replace primary fly ash is disclosed, using water-quenched slag from a zinc oxide fuming furnace, copper beneficiation tailings, and a small amount of activator as raw materials. The approximate proportions of the raw materials are 10-20 parts of water-quenched slag from a zinc oxide fuming furnace, 80-90 parts of copper beneficiation tailings, and 0.1 parts of activator. This production process fully utilizes solid waste from smelting plants, such as water-quenched slag from zinc oxide fuming furnaces and copper beneficiation tailings, turning waste into treasure through reasonable treatment and utilization, reducing environmental pollution and improving resource utilization. Simultaneously, this production process can also produce high-performance primary fly ash products, with good market prospects and economic benefits. The primary fly ash material is grayish-black in color and, after being quenched at 1200 degrees Celsius in a hot blast furnace, exhibits a glassy structure with virtually zero loss on ignition. When applying primary fly ash to concrete with special requirements or high grades, in addition to meeting requirements for fineness, water demand ratio, and loss on ignition, it can significantly reduce production costs, making it suitable for mass production and meeting market supply demands.

Description

[0001] This invention relates to the field of building materials, and more specifically, to a material production process for grade I fly ash. Background Technology

[0002] Chinese patent document CN102757193A discloses a composite admixture for concrete. This invention effectively controls chloride ion content, loss on ignition, and density by screening the raw materials of the admixture. Simultaneously, by screening water-reducing agents, it improves the fluidity of the slurry, reduces the water requirement ratio, ensures workability, and prevents shrinkage cracking. By adjusting the appropriate proportions, it significantly improves the early strength of ordinary Portland cement and ensures stable growth in later strength. In summary, the technical effects of this invention are improved construction efficiency, reduced costs, and guaranteed project quality. Fly ash, as a solid waste generated during coal-fired power generation, has always been a research hotspot for resource utilization. Traditional fly ash production processes mainly focus on improving the utilization rate and environmental performance of fly ash, but further research and improvement are needed to enhance the performance and quality of fly ash materials. Summary of the Invention

[0003] The purpose of this invention is to provide a material production process for a first-grade fly ash that is simple to operate, meets the required water ratio, has almost no loss on ignition, allows for flexible adjustment of the mortar activity index with the formula to exceed the target, and has stable overall quality, in order to solve the above-mentioned problems.

[0004] This invention provides a material production process for Grade I fly ash, which mainly includes the following steps:

[0005] Step 1: Raw material preparation. Water-quenched slag from a zinc oxide fuming furnace, tailings from copper beneficiation, and a small amount of activator are used as raw materials. The proportions are: 10-20 parts water-quenched slag from a zinc oxide fuming furnace, 80-90 parts tailings from copper beneficiation, and 0.1 parts activator. The chemical composition and content of the water-quenched slag from the zinc oxide fuming furnace are: 44.5% silicon dioxide, 5.2% aluminum oxide, 28.1% ferric oxide, 0.2% titanium dioxide, 12.3% calcium oxide, and 2.1% magnesium oxide. The chemical composition and content of the tailings from copper beneficiation are: 42.5% silicon dioxide, 9.4% aluminum oxide, 12.8% ferric oxide, 0.3% titanium dioxide, 27.7% calcium oxide, 3.1% magnesium oxide, and 0.1% loss on ignition.

[0006] Step 2: Pre-treatment. The raw materials undergo preliminary treatment in a hot air furnace to prepare for the subsequent grinding process.

[0007] Step 3: Grinding. The pretreated raw materials are fed into a vertical mill for grinding. The purpose of this process is to grind the raw materials to a certain fineness, that is, the specific surface area reaches 300㎡ / kg-500㎡ / kg, and the fineness is ≤2%. During the grinding process of the vertical mill, an activator is added. Through physical and chemical action, the cementing effect of the material is fully activated, thereby improving the strength and durability of the fly ash material.

[0008] Step 4: Screening. The ground material is sent to a classifier for screening to further control its specific surface area and fineness, ensuring product quality.

[0009] Step 5: Testing; adjusting product performance by controlling specific surface area and fineness.

[0010] Step Six: Collection. After the dust is collected by the bag filter, the final primary fly ash material is obtained. The primary fly ash material is transported to the storage silo via the transport equipment.

[0011] Furthermore, the zinc oxide fuming furnace water-quenched slag consists of 20 parts, copper-selected tailings 79.9 parts, and activator 0.1 parts.

[0012] Furthermore, the vertical mill equipment is used to grind the crushed and screened raw materials to a specific surface area of ​​500 m² / kg and a fineness of <2%, in order to ensure the uniformity and stability of the fly ash material.

[0013] Furthermore, the negative pressure sieve residue of the water-quenched slag from the secondary zinc oxide fuming furnace after grinding is ≤2%, the specific surface area is 503㎡ / kg, the water requirement ratio is 92%, and the 28-day strength activity index is 79%.

[0014] Furthermore, the negative pressure sieve residue of the copper-selected tailings after grinding is ≤2%, the specific surface area is 512㎡ / kg, the water requirement ratio is 95%, and the 28-day strength activity index is 99%.

[0015] Furthermore, the obtained Grade I fly ash material can be used in the production of concrete, cement, and brick building materials, as well as in other products that require high-performance fly ash materials.

[0016] Furthermore, the grade I fly ash material has a 45µm square mesh sieve residue fineness ≤1%, a water requirement ratio of 95%, a loss on ignition of 1.22%, a sulfur trioxide content of 0.56%, a moisture content of 0%, a free calcium oxide content of 0.08%, and a strength activity index of 84%.

[0017] Compared with the prior art, the present invention has the following advantages and effects:

[0018] 1. This production process makes full use of solid waste from smelters, such as water-quenched slag from zinc oxide fuming furnaces and tailings from copper beneficiation. Through reasonable treatment and utilization, waste is turned into treasure, reducing environmental pollution and improving resource utilization. At the same time, this production process can also produce high-performance Grade I fly ash products, which have good market prospects and economic benefits.

[0019] 2. The first-grade fly ash material is grayish-black in color, and the glassy substance produced by smelting in a hot blast furnace at 1200 degrees Celsius and water quenching has a loss on ignition of almost zero.

[0020] 3. The water requirement meets national and European standards, which can reduce the water-cement ratio of concrete or reduce the amount of water-reducing agent, thereby increasing concrete strength and reducing costs.

[0021] 4. It has a high and stable activity index, with an activity index of around 85% after 28 days. The formula production is very stable, and the activity increases significantly over a long period of time. It can replace part of the cement or mineral powder, reducing the cost of concrete raw materials.

[0022] 5. The fineness of the product can be far lower than the standard requirements, which can improve the interface structure of the fine aggregate transition zone in concrete, enabling the concrete to obtain better workability, density, impermeability and carbonation resistance, and increase the safety factor of concrete quality.

[0023] 6. When using Class I fly ash in concrete with special requirements or high grade, in addition to meeting the requirements for fineness, water demand ratio, and loss on ignition, it can significantly reduce production costs, making it suitable for mass production and meeting market supply demands. Attached Figure Description

[0024] Figure 1 is a process flow diagram provided in a practical example of the present invention. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0027] This application provides a material production process for Grade I fly ash, effectively addressing the problem that fly ash, a powder collected from the flue gas of power plants and a byproduct of power plants, suffers from inconsistent physicochemical properties such as fineness, water demand, loss on ignition, and mortar activity due to variations in coal type and quality, combustion processes, and operations. This instability negatively impacts the product quality of downstream customers. Furthermore, Grade I fly ash is typically used in concrete with special requirements or high strengths, where not only are requirements for fineness, water demand ratio, and loss on ignition more stringent, but it also faces challenges such as supply shortages, high raw material prices, and untimely raw material supply. (Example)

[0028] As shown in Figure 1, the technical solution in this application embodiment effectively solves the shortcomings of the prior art, and all indicators meet the requirements of national standards. It boasts stable quality, stable supply, and price advantages, and can completely replace other domestic and international Grade I fly ash products. The overall concept is as follows:

[0029] It includes the following six steps:

[0030] Step 1: Raw Material Preparation. The raw materials used include water-quenched slag from a zinc oxide fuming furnace, tailings from copper beneficiation, and a small amount of activator. The water-quenched slag from the zinc oxide fuming furnace is a product obtained during the production of zinc oxide by applying the water-quenching process to the slag treatment in a fuming furnace. This slag has potential hydraulic cementitious properties and can be used as a high-quality cement raw material with the help of activators such as cement clinker, lime, and gypsum. The chemical composition and content of the water-quenched slag from the zinc oxide fuming furnace are as follows: silicon dioxide 44.5%, aluminum oxide 5.2%, ferric oxide 28.1%, titanium dioxide 0.2%, calcium oxide 12.3%, and magnesium oxide 2.1%. The tailings from copper beneficiation, also known as copper tailings, are residual materials generated during the beneficiation of copper ore. These tailings typically contain some valuable but low-concentration metallic components. The chemical composition and content of the copper tailings are as follows: silicon dioxide 42.5%, aluminum oxide 9.4%, ferric oxide 12.8%, titanium dioxide 0.3%, calcium oxide 27.7%, magnesium oxide 3.1%, and loss on ignition 0.1%. The approximate proportions of the raw materials are: 20 parts of water-quenched slag from the zinc oxide fuming furnace, 79.9 parts of copper tailings, and 0.1 parts of activator.

[0031] Step Two: Pretreatment refers to the series of pretreatment steps that raw materials typically undergo before grinding begins. Pretreatment may include washing, drying, crushing, and sieving, with the aim of removing impurities and adjusting the particle size distribution or moisture content of the raw materials to better suit the subsequent grinding process. The raw materials undergo preliminary treatment in a hot blast stove to prepare for the subsequent grinding process. The hot blast stove is used to process the glassy material produced after blast furnace smelting and 1200°C water quenching, which has a near-zero loss on ignition and a grayish-black color. This glassy material typically has high hardness and brittleness, and direct grinding may encounter difficulties, such as low grinding efficiency and high energy consumption. Through the heating treatment in the hot blast stove, the glassy material undergoes a series of physical and chemical changes, thereby improving its grindability. The heating effect of the hot blast stove can promote phase transformation or decomposition of the mineral components in the glassy material, reducing its hardness and brittleness, making it easier to grind. Furthermore, heating allows moisture and gases to escape from the glass, reducing energy consumption and dust generation during grinding. The preliminary treatment in the hot blast furnace not only provides better raw material conditions for subsequent grinding but also helps improve the efficiency and product quality of the entire production process. This is also a common pretreatment method in industrial production, aiming to modify the physical and chemical properties of raw materials to better suit the requirements of subsequent production processes.

[0032] Furthermore, the hot blast stove plays a crucial role in temperature control: It provides a stable heat source: As the heat source in the primary fly ash production process, the hot blast stove provides stable and reliable thermal energy to the system. Precise temperature control can be achieved by adjusting the combustion parameters of the hot blast stove. It improves heat transfer efficiency: The hot air generated by the hot blast stove has a high temperature and flow rate, which can be quickly and evenly transferred to the primary fly ash production system. This helps improve heat transfer efficiency and reduce energy consumption. It allows for flexible temperature adjustment: The temperature of the hot blast stove can be flexibly adjusted by regulating parameters such as fuel supply and combustion air volume. During the primary fly ash production process, the temperature can be quickly adjusted according to actual needs to meet different production stages.

[0033] Step 3: Grinding. The pre-treated raw materials are fed into a vertical mill for grinding. Vertical mills typically utilize the relative motion between rotating grinding wheels and fixed liners to crush the raw materials into fine particles through impact, grinding, and shearing. Vertical mills are highly efficient, energy-saving, and produce uniform particle size distribution, making them widely used in various grinding operations. After grinding, the negative pressure sieve residue of the water-quenched slag from the secondary zinc oxide fuming furnace is ≤2%, the specific surface area is 503 m² / kg, the water requirement ratio is 92%, and the 28-day strength activity index is 79%. Furthermore, the negative pressure sieve residue of the copper-selected tailings after grinding is ≤2%, meaning that when passing through a sieve of a certain size, the mass of the undersize material (i.e., particles smaller than the sieve aperture) accounts for no more than 2% of the original sample mass. This indicator reflects the fineness of the particle size of the ground product; the lower the value, the finer the particle size. A specific surface area of ​​512 m² / kg is crucial for many applications because it directly affects the contact area between the material and other substances, thus influencing its chemical activity and physical properties. A larger specific surface area generally indicates higher activity or better adsorption performance. The water requirement is 95%, and the 28-day strength activity index is 99%. The purpose of this process is to grind the raw material to a certain fineness. Due to the low alkalinity coefficient of the material, both physical and chemical activation methods are required. During the vertical mill grinding process, an activator is added to fully activate the gelation effect of the material through physical and chemical reactions, thereby improving the strength, durability, and other properties of the fly ash material. While the activator addresses the product's activity, it should also resolve the contradiction between increasing the water requirement as the material is ground finer and the specific surface area is higher.

[0034] Step Four: Screening. The ground material is sent to an air classifier for screening to further control its specific surface area and fineness, ensuring product quality. During production, the specific surface area needs to be controlled above 500 m² / kg (fineness ≤2% on a negative pressure sieve with a 0.045 mm particle size) to address issues such as low material alkalinity coefficient. The product fineness can be far lower than the standard requirements, improving the interface structure of the fine aggregate transition zone in concrete, resulting in better workability, density, impermeability, and carbonation resistance, thus increasing the safety factor of concrete quality.

[0035] Step 5: Testing. By controlling the specific surface area and fineness, the product's performance is adjusted. Water demand meets national and European standards, which can reduce the water-cement ratio or the amount of water-reducing agent, thereby increasing concrete strength and reducing costs. In the concrete production process, adjusting the product's performance by controlling the specific surface area and fineness of raw materials is a crucial step. This control not only helps ensure concrete quality but also enhances concrete strength and reduces costs by optimizing the water-cement ratio and water-reducing agent dosage. Specific Surface Area: Specific surface area is the total surface area per unit mass of material. In concrete, cement particles with a larger specific surface area react more effectively with water, forming more hydration products, thus increasing concrete strength. Furthermore, a larger specific surface area increases the contact area between cement particles and aggregates, improving the density and durability of the concrete. Fineness: Fineness refers to the particle size distribution of materials. In concrete, finer particles fill the voids between aggregates, reducing porosity and improving the density and strength of the concrete. Simultaneously, fineness also affects the flowability and workability of concrete. By controlling the specific surface area and fineness of raw materials, the properties of concrete can be adjusted to meet different engineering requirements. For example, in applications requiring high-strength concrete, the specific surface area and fineness of the raw materials can be increased; while in applications requiring high-flowability concrete, the fineness of the raw materials needs to be appropriately reduced. During concrete production, it is essential to ensure that the product complies with relevant national and European standards. These standards typically specify requirements for concrete strength, durability, flowability, and workability. By controlling the specific surface area and fineness of the raw materials, it is possible to ensure that the concrete product meets these standards and satisfies engineering requirements.

[0036] Step Six: Collection. Dust is collected via baghouse dust collection. Baghouse dust collection technology is a highly efficient dust collection method. Through a combination of aerodynamics and filtration principles, it effectively captures fine dust particles, preventing them from entering the air and causing pollution. This technology not only improves the cleanliness of the production environment but also protects worker health and makes the entire production process environmentally friendly because it significantly reduces particulate matter emissions into the atmosphere. After baghouse dust collection, the primary fly ash material is transported to a storage silo via conveyor equipment for subsequent production use. This step ensures the orderly management and use of raw materials and also guarantees the continuity and stability of the production process. By controlling the specific surface area and fineness of raw materials, adopting baghouse dust collection technology, and managing raw materials in an orderly manner, the concrete production process can achieve a dual improvement in environmental protection and economic benefits while ensuring product quality. These measures help enterprises better meet market demands, win consumer trust and support, and promote sustainable development.

[0037] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A material production process for Grade I fly ash, mainly including the following steps: Step 1: Raw material preparation. Water-quenched slag from a zinc oxide fuming furnace, copper tailings, and a small amount of activator are used as raw materials. The proportions are: 10-20 parts water-quenched slag from a zinc oxide fuming furnace, 80-90 parts copper tailings, and 0.1 parts activator. The chemical composition and content of the water-quenched slag from the zinc oxide fuming furnace are: 44.5% silicon dioxide, 5.2% aluminum oxide, 28.1% ferric oxide, 0.2% titanium dioxide, 12.3% calcium oxide, and 2.1% magnesium oxide. The chemical composition and content of the copper tailings are: 42.5% silicon dioxide, 9.4% aluminum oxide, 12.8% ferric oxide, 0.3% titanium dioxide, 27.7% calcium oxide, 3.1% magnesium oxide, and 0.1% loss on ignition. Step 2: Pretreatment. The raw materials undergo preliminary treatment in a hot blast furnace to prepare for the subsequent grinding process. Step 3: Grinding. The pretreated raw materials are fed into a vertical mill for grinding. The purpose of this process is to grind the raw materials to a certain fineness, that is, the specific surface area reaches 300㎡ / kg-500㎡ / kg, and the fineness is ≤2%. During the grinding process of the vertical mill, a chemical activator is added at the same time. Through physical and chemical action, the cementing effect of the material is fully activated, thereby improving the strength and durability of the fly ash material. Step 4: Screening. The ground material is sent to a classifier for screening to further control its specific surface area and fineness, ensuring product quality. Step 5: Testing. By controlling the specific surface area and fineness, the performance of the product can be adjusted. Step Six: Collection. After the dust is collected by bag filter, the product is collected to obtain the final grade 1 fly ash material.

2. The material production process for primary fly ash according to claim 1, characterized in that, The composition includes 20 parts of water-quenched slag from the zinc oxide fuming furnace, 79.9 parts of tailings from copper selection, and 0.1 parts of activator.

3. The material production process for primary fly ash according to claim 1, characterized in that, The vertical mill equipment described above is used to grind the crushed and screened raw materials to a specific surface area of ​​500 m² / kg and a fineness of <2%, in order to ensure the uniformity and stability of the fly ash material.

4. The material production process for primary fly ash according to claim 1, characterized in that, The negative pressure sieve residue of the pulverized zinc oxide fuming furnace water-quenched slag after grinding is ≤2%, the specific surface area is 503㎡ / kg, the water requirement ratio is 92%, and the 28-day strength activity index is 79%.

5. The material production process for primary fly ash according to claim 1, characterized in that, The negative pressure sieve residue of the copper-selected tailings after grinding is ≤2%, the specific surface area is 512㎡ / kg, the water requirement ratio is 95%, and the 28-day strength activity index is 99%.

6. The material production process for any one of the grade 1 fly ash according to claims 1 to 4, characterized in that, The resulting Grade I fly ash material can be used in the production of concrete, cement, and brick building materials, as well as in other products that require high-performance fly ash materials.

7. The material production process for primary fly ash according to claim 6, characterized in that, The grade I fly ash material has the following characteristics: 45 μm square mesh sieve residue fineness ≤1%, water requirement ratio 95%, loss on ignition 1.22%, sulfur trioxide 0.56%, moisture content 0%, free calcium oxide 0.08%, and strength activity index 84%.

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