Method for preparing light cement aggregate from coal gasification slag

Abstract

The invention discloses a method for preparing light cement aggregate from coal gasification slag, which comprises the following steps: step 1, dispersing the coal gasification slag with the mass fraction of 10-40% in water, adding a hydrochloric acid solution with the concentration of 1-5M, aging for 2-6 hours, and then filtering; dispersing the filtered precipitate in water according to a mass fraction of 20-50%, adding ammonia water with a concentration of 2-6 M, aging for 2-6 h, and then filtering; step 2, washing the obtained precipitate with water, then sanding to obtain fine slurry, putting the slurry into a homogenizer for continuous dispersion, and then drying to obtain powder; and 3, calcining the powder at 600-800 DEG C to obtain the light cement aggregate. The industrial waste coal gasification slag can be converted into a building material with a high additional value, the resource utilization rate of the coal gasification slag is remarkably increased, the technological process is simple, the cost of required equipment and raw materials is low, no other extra chemical additives are added except the acid liquor and the alkali liquor, and the method has a good industrial application prospect.

Description

Technical Field

[0001] The invention relates to the field of building materials, and in particular to a method for preparing lightweight cement aggregate by utilizing coal gasification slag. Background Art

[0002] With the acceleration of industrialization, coal is widely used as an important energy source around the world. However, the gasification slag produced during the coal gasification process is an industrial waste, and its disposal and resource utilization have become urgent issues to be solved. Traditionally, gasification slag is mainly disposed of by landfill or stockpiling, which not only occupies a large amount of land resources, but also may cause potential pollution to the environment. Therefore, the development of efficient technology for resource utilization of gasification slag has important economic and environmental significance.

[0003] In the field of building materials, lightweight cement aggregate, as an important component of concrete, has attracted widespread attention due to its advantages of reducing structural weight and improving thermal insulation performance. At present, commonly used lightweight cement aggregate materials include expanded perlite, expanded vermiculite, fly ash, etc. However, these materials have certain limitations. For example, the source of fly ash is limited, and its physical properties are subject to coal sources and combustion conditions, which makes it difficult to meet the demand for high-performance lightweight cement aggregate. In addition, some lightweight aggregates have high energy consumption and high preparation costs during the production process, which limits their large-scale application.

[0004] In view of the above problems, how to efficiently and cost-effectively convert coal gasification slag into lightweight cement aggregate with excellent performance has become a research hotspot. In the prior art, some methods improve the physical properties of coal gasification slag through chemical treatment, but the process is complicated and difficult to achieve industrial production. Therefore, there is an urgent need for a method for preparing lightweight cement aggregate with simple process, economic feasibility and effective improvement of the utilization rate of coal gasification slag. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing lightweight cement aggregate from coal gasification slag, which has simple steps, is easy to operate and has low cost.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention provides a method for preparing lightweight cement aggregate from coal gasification slag, comprising the following steps:

[0008] Step 1, dispersing 10-40% of coal gasification slag in water, adding 1-5M hydrochloric acid solution, the mass fraction of which is 15-30% of water, aging for 2-6 hours, and then filtering; dispersing the filtered precipitate in water at a mass fraction of 20-50%, adding 2-6M ammonia water, the mass fraction of which is 15-30% of water, aging for 2-6 hours, and then filtering;

[0009] Step 2: Wash the obtained precipitate with water, then sand grind it to obtain a fine slurry, place the slurry in a homogenizer to continue dispersing it, and then dry it to obtain a powder;

[0010] Step three, calcining the powder at 600-800° C. to obtain lightweight cement aggregate.

[0011] Preferably, in step 1, the filtration method is vacuum filtration.

[0012] Preferably, in step 2, the sand milling time is 3 to 9 hours, and the sand milling medium is ethanol.

[0013] Preferably, in step 2, the homogenizer processing time is 6 to 12 hours.

[0014] Preferably, in step 2, the drying temperature is 40-80° C., and the drying time is 6-12 hours.

[0015] Preferably, in step three, the calcination time is 6 to 18 hours.

[0016] The lightweight cement aggregate prepared by the invention has low density and can replace fly ash as cement aggregate, thereby improving the utilization efficiency of industrial resources.

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

[0018] 1. High resource utilization rate. It converts industrial waste gasification slag into high value-added building materials, significantly improving the resource utilization rate of gasification slag and reducing environmental pollution.

[0019] 2. Simple and economical process: This method has clear steps, simple process flow, low cost of equipment and raw materials, and no other additional chemical additives except acid and alkali solution, so it has good prospects for industrial application.

[0020] 3. Superior performance: The produced lightweight cement aggregate has low density and good physical and mechanical properties, can effectively replace fly ash, and meet the needs of modern construction for lightweight and high-performance materials.

[0021] 4. Significant environmental benefits: By reducing the emission of industrial waste, the burden on the environment is reduced. At the same time, the chemical treatment and heat treatment in the production process can achieve efficient recycling of resources, which meets the requirements of sustainable development. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a line graph comparing the densities of the aggregates prepared in Examples 1 to 3 and the comparative example. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] Example 1

[0025] Take 30% coal gasification slag by mass, disperse it in water, add 3M hydrochloric acid solution, the mass fraction of hydrochloric acid is 20% of water, and age it at room temperature for 4 hours. Filter the mixed solution by vacuum filtration to obtain a filtered precipitate. Disperse the filtered precipitate in water at a mass fraction of 35%, add 4M ammonia water, the mass fraction of ammonia water is 25% of water, and age it at room temperature for 5 hours. Filter it again by vacuum filtration to obtain a filtered precipitate. Wash the obtained precipitate with deionized water three times until the pH value of the washing liquid is close to neutral. Sand grind the precipitate with a sand mill for 6 hours, and use ethanol as the sand grinding medium to obtain a fine slurry. Place the fine slurry in a homogenizer for homogenization for 8 hours to further disperse the slurry. Dry the homogenized slurry at 60°C for 8 hours to obtain a dry powder. Place the dry powder in a furnace preheated to 700°C, calcine for 12 hours, and obtain lightweight cement aggregate after cooling.

[0026] Example 2

[0027] Take 20% coal gasification slag by mass, disperse it in water, add 2M hydrochloric acid solution with a mass fraction of 18%, and age it at room temperature for 3 hours. Filter the mixed solution by vacuum filtration to obtain a filtered precipitate. Disperse the filtered precipitate in water at a mass fraction of 25%, add 5M ammonia water with a mass fraction of 20%, and age it at room temperature for 6 hours. Filter it again by vacuum filtration to obtain a filtered precipitate. Wash the obtained precipitate with deionized water four times until the pH value of the washing liquid is close to neutral. Sand grind the precipitate with a sand mill for 5 hours, and use ethanol as the sand grinding medium to obtain a fine slurry. Place the fine slurry in a homogenizer for homogenization for 10 hours to further disperse the slurry. Dry the homogenized slurry at 70°C for 10 hours to obtain a dry powder. Place the dry powder in a furnace preheated to 750°C, calcine for 15 hours, and obtain lightweight cement aggregate after cooling.

[0028] Example 3

[0029] Take 40% coal gasification slag by mass, disperse it in water, add 1M hydrochloric acid solution, the mass fraction of hydrochloric acid is 25%, and age it at room temperature for 2 hours. Filter the mixed solution by vacuum filtration to obtain a filtered precipitate. Disperse the filtered precipitate in water at a mass fraction of 50%, add 6M ammonia water, the mass fraction of ammonia water is 30%, and age it at room temperature for 6 hours. Filter it again by vacuum filtration to obtain a filtered precipitate. Wash the obtained precipitate with deionized water five times until the pH value of the washing liquid is close to neutral. Sand grind the precipitate with a sand mill for 7 hours, and use ethanol as the sand grinding medium to obtain a fine slurry. Place the fine slurry in a homogenizer for homogenization for 12 hours to further disperse the slurry. Dry the homogenized slurry at 80°C for 12 hours to obtain a dry powder. Place the dry powder in a furnace preheated to 800°C, calcine for 18 hours, and cool to obtain a lightweight cement aggregate.

[0030] Comparative Example

[0031] Take 40% coal gasification slag by mass, disperse it in water, add 1M hydrochloric acid solution with a mass fraction of 25%, and age it at room temperature for 2 hours. Filter the mixed solution by vacuum filtration to obtain a filtered precipitate. Disperse the filtered precipitate in water at a mass fraction of 50%, add 6M ammonia water with a mass fraction of 30%, and age it at room temperature for 6 hours. Filter it again by vacuum filtration to obtain a filtered precipitate. Wash the obtained precipitate with deionized water five times until the pH value of the washing liquid is close to neutral. Sand grind the precipitate with a sand mill for 7 hours, and use ethanol as the sand grinding medium to obtain a fine slurry. Dry the sand-milled slurry at 80°C for 12 hours to obtain a dry powder. Place the dry powder in a furnace preheated to 800°C, calcine for 18 hours, and obtain lightweight cement aggregate after cooling.

[0032] Figure 1 It is a density comparison line chart of the aggregates prepared in Examples 1-3 and the comparative example. Figure 1 As shown, the aggregate powders prepared in Examples 1-3 have similar particle sizes due to the homogenization treatment. Since the aggregates are mainly composed of siliceous and carbonaceous materials, fine particles with large surface energy can be formed, so the packing density is lower, and the final density is less than 1g / cm 3 , while the comparative example did not perform homogenization of particle size, thus forming a gradation and having a higher bulk density. In summary, the material prepared by the method provided by the present invention has a low density, can replace fly ash in cement, and improve the efficiency of industrial resource utilization.

[0033] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A method for preparing lightweight cement aggregate from coal gasification slag, characterized in that: The following steps are involved: Step 1, dispersing 10-40% of coal gasification slag in water, adding 1-5M hydrochloric acid solution, the mass fraction of which is 15-30% of water, aging for 2-6 hours, and then filtering; dispersing the filtered precipitate in water at a mass fraction of 20-50%, adding 2-6M ammonia water, the mass fraction of which is 15-30% of water, aging for 2-6 hours, and then filtering; Step 2: Wash the obtained precipitate with water, then sand grind it to obtain a fine slurry, place the slurry in a homogenizer to continue dispersing it, and then dry it to obtain a powder; Step three, calcining the powder at 600-800° C. to obtain lightweight cement aggregate.

2. The method for preparing lightweight cement aggregate from coal gasification slag according to claim 1, characterized in that: In step 1, the filtration method is vacuum filtration.

3. The method for preparing lightweight cement aggregate from coal gasification slag according to claim 1, characterized in that: In step 2, the sand milling time is 3 to 9 hours, and the sand milling medium is ethanol.

4. The method for preparing lightweight cement aggregate from coal gasification slag according to claim 1, characterized in that: In step 2, the homogenizer processing time is 6 to 12 hours.

5. The method for preparing lightweight cement aggregate from coal gasification slag according to claim 1, characterized in that: In step 2, the drying temperature is 40 to 80° C., and the drying time is 6 to 12 hours.

6. The method for preparing lightweight cement aggregate from coal gasification slag according to claim 1, characterized in that: In step 3, the calcination time is 6 to 18 hours.

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