CN110194485B - Low-temperature preparation of CaTiO by using sintered flue gas desulfurization ash3Method for producing powder - Google Patents

Abstract

The invention provides a method for preparing CaTiO by sintering flue gas desulfurization ash at low temperature₃A powder method belongs to the technical field of industrial solid waste comprehensive utilization and inorganic non-metallic material preparation. The invention specifically comprises the following steps: desulfurizing ash and TiO from sintering flue gas₂Mixing with carbonate-containing alkali metal salt powder, heating to above 700 deg.C, calcining, soaking the obtained product in water, filtering, cleaning, and drying to obtain CaTiO₃And (3) powder. The invention takes the cheap sintering flue gas desulfurization ash as the Ca source, the synthesis temperature is obviously reduced compared with the traditional solid phase method, and the grain size of the obtained product is smaller. The method has simple process and low cost, can realize high value-added utilization of the sintering flue gas desulfurization ash, and has remarkable social and economic benefits.

Description

Low-temperature preparation of CaTiO by using sintered flue gas desulfurization ash3Method for producing powder

Technical Field

The invention belongs to the technical field of industrial solid waste comprehensive utilization and inorganic non-metallic material preparation, and particularly relates to a method for preparing CaTiO by using sintered flue gas desulfurization ash at low temperature₃A method for preparing powder.

Background

The maturity and development of the sintering flue gas desulfurization technology effectively solve the problem of flue gas pollution, but a large amount of desulfurization ash is generated along with the flue gas pollution, so that new solid waste pollution is caused. At present, the desulfurization ash treatment technology is not mature enough, most of the desulfurization ash treatment technology can only be stockpiled, a large amount of precious land resources are occupied, and secondary pollution to the environment is possibly caused. The existing development and utilization of the desulfurized fly ash mainly focus on the aspects of cement, wall filling materials, soil modification and the like, and the added value of the product is relatively low.

Perovskite type CaTiO₃Is a basic inorganic material having excellent dielectric characteristics, temperature characteristics, mechanical characteristics and optical characteristics, and is widely used in the fields of ceramic capacitors, thermistors, microwave antennas, luminescent materials, photocatalytic materials, stainless steel welding materials and the like. At present, CaTiO₃The preparation method of the powder mainly comprises the following three methods: (1) high-temperature solid phase method: with CaCO₃Or CaO and TiO₂The mixed powder is used as a raw material to be calcined at high temperature, the process is simple, but the synthesis temperature is generally more than 1350 ℃, and the particle size of the obtained powder is larger; (2) mechanochemical method: with CaO and TiO₂The mixed powder is taken as a raw material, and the CaTiO is formed by the mixed powder through amorphization, chemical reaction, nucleation, grain growth and other processes through mechanical force generated by high-energy ball milling₃The method does not need high temperature, the grain size of the synthesized powder is small, but the synthesis time is long, and the product purity is not easy to control; (3) liquid phase method: including coprecipitation, hydrothermal, sol-gel, etc., to obtain CaTiO₃The powder has high purity and small grain diameter, but the raw material cost is high and the process is complex.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a method for preparing CaTiO by using sintered flue gas desulfurization ash at low temperature₃The powder method is designed for the consideration of process, cost and performance.

In order to achieve the technical purpose, the invention is realized by the following technical scheme.

The invention relates to a method for preparing CaTiO by sintering flue gas desulfurization ash at low temperature₃The powder preparation method specifically comprises the following steps:

(1) desulfurizing ash and TiO from sintering flue gas₂Mixing with alkali metal salt powder;

ca element and TiO in the sintering flue gas desulfurization ash₂In a molar ratio of 1: 1; the alkali metal salt is Na₂CO₃、K₂CO₃、LiCO₃、NaCl、KCl、LiCl、Na₂SO₄、K₂SO₄、Li₂SO₄And at least one carbonate; CO in the alkali metal salt₃ ^2-The molar ratio of S element in the ion and sintering flue gas desulfurization ash is 1-3: 1.

(2) putting the mixed powder obtained in the step (1) into a corundum crucible, heating and calcining, and naturally cooling;

the calcination temperature is above 700 ℃, and the heat preservation time is 1-5 h.

(3) Soaking the mixture obtained in the step (2) in water for 1-3 h, filtering, cleaning and drying to obtain CaTiO₃And (3) powder.

Further, the alkali metal salt is Na₂CO₃。

The main raw material used in the invention is semi-dry sintering flue gas desulfurization ash, and the main crystalline substance is CaSO₃.0.5H₂O and CaCO₃Typical compositions are shown in table 1. The content of Ca element in the desulfurized fly ash is up to 42.36 wt.%, and can be CaTiO₃The synthesis of (3) provides a source of Ca. In addition, the desulfurized fly ash also contains rich SO₃ ^2-Or SO₄ ^2-、Cl^-、K⁺And Na⁺And the like.

Table 1 main chemical composition (wt.%) of sintering flue gas desulfurization ash

The main reaction process and principle of the invention are as follows:

(1) CO in added alkali metal salt₃ ^2-The ions remove CaSO in the sintering flue gas desulfurization ash in the heating process₃Conversion to CaCO₃And adding SO₃ ^2-By oxidation to SO₄ ^2-。

(2) CaCO formed by the above reaction₃And CaCO originally contained in the sintered flue gas desulfurization ash₃、 CaO、Ca(OH)₂Etc. with TiO₂Reaction ofFormation of CaTiO₃。

(3) SO in or produced by the reaction of the starting materials₄ ^2-、Cl^-、K⁺、Na⁺、Ca²⁺The plasma promotes the formation of low-melting-point substances in the calcining process, provides a liquid phase environment for reaction, promotes the diffusion and reaction of reaction substances, effectively reduces the synthesis temperature and inhibits the grain growth of product particles.

Compared with the prior art, the invention has the following technical effects:

(1) the sintering flue gas desulfurization ash is used as a Ca source, and the cost of the raw materials is low.

(2) Makes full use of a large amount of SO in the sintering flue gas desulfurization ash₃ ^2-、SO₄ ^2-、Cl^-、K⁺、Na⁺、Ca²⁺The characteristic that the plasma can promote the generation of liquid phase substances in the calcining process can ensure that the CaTiO₃The synthesis temperature of the method is reduced from 1350 ℃ of the traditional solid phase method to 700-900 ℃, the particle size of the product is small, and the ions can be removed by a simple water washing mode.

(3) The method has simple process and low cost, can realize high value-added utilization of the sintering flue gas desulfurization ash, and has remarkable social and economic benefits.

Drawings

FIG. 1 shows CaTiO prepared in example 1₃X-ray diffraction (XRD) pattern of the powder.

FIG. 2 shows CaTiO prepared in example 1₃Scanning Electron Microscope (SEM) photographs of the powder.

Detailed Description

For further understanding of the technical contents of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and examples, but the present invention is not limited to the examples.

Example 1

1.000g of sintering flue gas desulfurization ash, 0.844g of TiO₂And 1.119g Na₂CO₃Mixing the powder uniformly, placing into a corundum crucible, heating to 700 deg.C, keeping the temperature for 5h, naturally cooling, soaking the product in the corundum crucible for 2h, filtering, washing with water and ethanol respectively for multiple times,drying to obtain CaTiO₃And (3) powder.

FIG. 1 shows CaTiO prepared in this example₃The XRD pattern of the powder shows that the powder prepared in this example is crystalline CaTiO₃And no other impurity phase. FIG. 2 shows CaTiO prepared in this example₃In the SEM photograph of the powder, it was found that the particle size of the powder was about 100 nm.

Example 2

1.000g of sintering flue gas desulfurization ash, 0.844g of TiO₂And 1.459g K₂CO₃Uniformly mixing the powder, putting the mixture into a corundum crucible, heating the mixture to 700 ℃, preserving heat for 3 hours, naturally cooling the mixture, putting the product into the corundum crucible, soaking the product for 2 hours, filtering the product, respectively washing the product with water and ethanol for multiple times, and drying the product to obtain the CaTiO₃And (3) powder.

Example 3

1.000g of sintering flue gas desulfurization ash, 0.844g of TiO₂And 2.003g of Na₂CO₃Mixing the powders, placing into corundum crucible, heating to 800 deg.C, keeping the temperature for 1 hr, naturally cooling, soaking the product in the corundum crucible for 2 hr, filtering, washing with water and ethanol for several times, and drying to obtain CaTiO₃And (3) powder.

Example 4

1.000g of sintering flue gas desulfurization ash and 0.844g of TiO₂、0.425g Na₂CO₃0.647g KCl and 0.220 g Na₂SO₄Mixing the powders, placing into corundum crucible, heating to 900 deg.C, keeping the temperature for 3 hr, naturally cooling, soaking the product in water for 3 hr, filtering, washing with water and ethanol for several times, and drying to obtain CaTiO₃And (3) powder.

Claims (2)

1. Low-temperature preparation of CaTiO by using sintered flue gas desulfurization ash₃The powder preparation method is characterized by comprising the following steps:

(1) desulfurizing ash and TiO from sintering flue gas₂Mixing with alkali metal salt powder;

ca element and TiO in the sintering flue gas desulfurization ash₂In a molar ratio of 1: 1; the alkali metal salt is Na₂CO₃、K₂CO₃、LiCO₃、NaCl、KCl、LiCl、Na₂SO₄、K₂SO₄And Li₂SO₄And at least one carbonate; CO in the alkali metal salt₃ ^2-The molar ratio of S element in the ion and sintering flue gas desulfurization ash is 1-3: 1;

(2) putting the mixed powder obtained in the step (1) into a corundum crucible, heating and calcining, and naturally cooling;

the calcination temperature is above 700 ℃, and the heat preservation time is 1-5 h;

(3) soaking the mixture obtained in the step (2) in water for 1-3 h, filtering, cleaning and drying to obtain CaTiO₃And (3) powder.

2. The low-temperature preparation of CaTiO with the sintered flue gas desulfurization ash of claim 1₃A method for producing a powder, characterized in that the alkali metal salt is Na₂CO₃。

Images