CN107777694B

CN107777694B - Method for preparing sphene from xonotlite

Info

Publication number: CN107777694B
Application number: CN201711158887.7A
Authority: CN
Inventors: 李芳菲; 郭宏刚; 薛兵; 蒋引珊; 夏茂盛; 巨昊; 霍明远; 徐远俊; 韩明磊; 任桂花
Original assignee: Jilin University
Current assignee: Jilin University
Priority date: 2017-11-20
Filing date: 2017-11-20
Publication date: 2020-09-15
Anticipated expiration: 2037-11-20
Also published as: CN107777694A

Abstract

The invention relates to a method for preparing sphene from xonotlite, belonging to the field of inorganic non-metallic material production. The method makes full use of the same calcium-silicon ratio of the sphene to the xonotlite and the chemical activity of the sphene, and introduces the excess chemical energy in the calcium-silicon raw material into the titaniferous sulfate hydrolysis product, thereby realizing the generation of the sphene at a lower calcination temperature and ensuring the purity of the sphene in the product. The method has the advantages of simple synthesis process, low raw material cost, low requirement on equipment, low energy consumption, little pollution and high titanite purity, can effectively solve the problems of easy yellowing and high cost of the glaze surface of the existing titanium opacifier, and is an ideal substitute of the zirconium silicate opacifier.

Description

Method for preparing sphene from xonotlite

Technical Field

The invention belongs to the field of production of inorganic non-metallic materials, and relates to a method for preparing a calcium silicate-TiO composite material₂The method for preparing sphene as a raw material can be used as a glaze opacifier to be applied to the ceramic industry.

Background

In recent years, with the development of the ceramic industry, the opaque glaze has wide application in various aspects such as daily ceramics, artistic ceramics, building ceramics, sanitary ware and the like. The opaque glaze, also called 'ground glaze', is transparent glaze with opacifier added to produce fine crystal, bubble, liquation, etc. to scatter lightAnd obtain opaque glaze surface, which can cover the color and defect of blank body. Opacifier is the most critical component in opacified glaze, and is subjected to tin oxide (SnO)₂) Zinc oxide (ZnO), zirconium oxide (ZrO)₂) And phosphates and the like, zirconium silicate (ZrSiO) is mainly used at present₄) As an opacifying agent. It has high refractive index (1.94), high temperature stability, and stable application technology and process through long-term use. But ZrSiO₄There are also some drawbacks: (1) the zirconium silicate raw material has large particles and high hardness, and is not easy to be made into fine powder. (2) It has high melting point and high energy consumption. (3) The raw material source limitation is large, the raw material mainly depends on import, the purchase price is high, and the influence on the ceramic cost is large. (4) The raw material contains a small amount of radioactive associated minerals and has radioactive hazards. Therefore, it is imperative to actively seek and develop a novel opacifier which can replace zirconium silicate.

TiO₂The titanium-containing compound has high refractive index and good opacifying effect, can be used as an opacifying agent in ceramic glaze, and has the characteristics of no toxicity, no harm, low price and environmental friendliness, and is expected to become a good substitute of zirconium silicate. But high refractive index rutile TiO₂Titanite (CaTiSiO) which is easily yellowed during the firing of ceramics and has stable properties₅Refractive index of 1.89-2.02) is more preferable as the titanium-based opacifier. As early as the 30 s of the 20 th century, TiO was first reported in the United states₂The rutile phase TiO is precipitated in the high-temperature sintering process as an opacifier for the research of porcelain glaze₂Due to non-stoichiometry and coarse particles, yellowing of the glaze can result from interfering rayleigh scattering. In 1961, Japan first introduced a Tiu patent by adding TiO at the same time₂CaO and SiO₂(different molar ratios) control of TiO₂All with sphene (CaTiSiO)₅) The formal precipitation of (A) is described. Xuxia Xixia et al considered that the glaze effect is best when the opacified phase is sphene, at which time CaO/TiO₂The molar ratio is about 1.5, and the problem that the traditional titanium glaze is easy to yellow is solved. The research results show that the effective measures for solving the yellowing problem of the glaze surface of the titanium opacifier are to reduce the precipitation degree of rutile phase in the ceramic firing process and increaseStrong TiO₂Reaction behavior of sphene.

Sphene belongs to monoclinic island-like structure silicate minerals, is one of the most stable mineral phases on the earth, has strong surface reflection capability, and is an ideal titanium opacifier. CN 1045963a describes a sphene-type compound emulsion and its preparation method. With CaO (CaCO)₃)、TiO₂、SiO₂(Quartz) powder as main raw material, P₂O₅(Ca₃(PO₄)₂Or calcined ashes) or other phosphates as TiO₂The sphene type composite opacifier is synthesized by calcining at the high temperature of 1000-1400 ℃. In order to ensure high rate of formation of sphene type structure, wherein TiO₂CaO and SiO₂The content ratio is preferably close to the molecular formula of sphene (CaO. TiO)₂·SiO₂) The molar ratio of (a). The composite opacifier synthesized by the invention can be directly introduced into raw glaze or made into frits to be added into the glaze, and has good opacifying effect. The research on the synthesis of titanic ore by the solid phase method of Yi Xixia and Yang Ke introduces a titanium titanic ore compound prepared by using anhydrous calcium carbonate, titanium dioxide and silicon dioxide as raw materials and respectively preserving heat for a certain time at different temperatures according to different raw material proportions by a high-temperature solid phase method. And adding the synthesized titanium sphene into the basic glaze formula according to the addition of 5%, wherein the optimal synthesis conditions of the titanium sphene with the best glaze whiteness are as follows: 42.70 percent of anhydrous calcium carbonate, 30.27 percent of titanium dioxide and 28.02 percent of silicon dioxide, the synthesis temperature is 1240 ℃, and the heat preservation time is 30 min. The high-temperature solid-phase synthesis method is the main synthesis method of sphene at present, but the high-temperature solid-phase synthesis method is excessively dependent on the high-temperature solid-phase reaction between a calcareous raw material and a siliceous raw material, and is difficult to be fully carried out due to the limitation of mass transfer conditions, so the purity of the sphene synthesized by the solid-phase method is generally not ideal, and the energy consumption is very high. Besides the solid-phase method, there are also a few reports on the synthesis of sphene with higher purity by using the liquid-phase method, but the raw materials used in the sol-gel method or the liquid-phase sintering method are generally pure chemical reagents, so that the raw material cost is high, the preparation process is complicated, the liquid-phase product also needs to be calcined at a high temperature of more than 1200 ℃ to synthesize the sphene with ideal purity, the synthesis cost is very high, and the serious limitation is also causedThe titanite opacifier is popularized and applied.

Xonotlite (Ca)₆[Si₆O₁₇](OH)₂) Belongs to monoclinic system chain silicate, is more needle-shaped or fibrous, has good thermal stability and safe use, and is generally applied to cement-based materials, heat insulation materials, flame retardant materials, reinforcing and toughening materials and adsorbing materials. The density of the product of the heat-insulating material made of xonotlite can be less than 135kg/m³The use temperature can reach 1000 ℃. The paper product toughened by the xonotlite fiber has the characteristics of heat resistance, fire resistance, safety, no toxicity and the like. The chemical components of the xonotlite are relatively stable, the calcium-silicon ratio of the xonotlite is completely consistent with that of the sphene, and the xonotlite has good chemical reaction activity under an acidic condition, so that a prerequisite condition is provided for preparing the sphene by taking the xonotlite as a raw material. Compared with the conventional reagent for synthesizing sphene in liquid phase, the xonotlite as an industrial raw material is lower in price, which is beneficial to industrial production and application. However, no studies have been reported on the preparation of sphene from xonotlite as a raw material.

Aiming at the problems encountered in the synthesis of sphene, the invention provides a method for synthesizing high-purity sphene at low temperature by using a high-activity silicocalcareous raw material (xonotlite) from a liquid-phase system. The invention makes full use of xonotlite in TiO₂The chemical reaction activity in the acid precursor introduces the surplus chemical energy into the liquid phase synthesis system of the sphene, thereby obviously reducing the calcination phase transition temperature of the sphene phase in the liquid phase synthesis product and saving the energy consumption for mass production. Moreover, the used calcium-silicon raw materials are common industrial raw materials, the cost of the synthetic raw materials is obviously lower than that of the existing liquid phase method, and the industrial production can be realized. Meanwhile, the proportion of calcium and silicon in the chemical components of the xonotlite is the same as that of the sphene, so that the sphene produced by the method has ideal purity, and the problems that the glaze surface of the existing titanium opacifier is easy to yellow and high in cost are solved.

Disclosure of Invention

The invention aims to provide a synthesis method with simple process, low production cost, low calcination temperature and high sphene product purity aiming at the problems of high calcination temperature and incomplete reaction in high-temperature solid-phase synthesis, and the technical defects of complicated liquid-phase synthesis process, high production cost and the like.

The purpose of the invention is realized by the following technical scheme:

1) preparing a 0.03-0.5 mol/L aqueous solution from titanium-containing sulfate serving as a titanium source, and magnetically stirring for 0.5-1 h to fully dissolve the titanium-containing sulfate;

2) adjusting the pH value of the solution to 2-3 by using sodium hydroxide, then adding a proper amount of xonotlite powder to ensure that the molar ratio of calcium to titanium in the solution is 0.86-1.05, and uniformly stirring;

3) dropwise adding sodium hydroxide into the mixed solution to adjust the pH value of the system to 6-8, and placing the system in a water bath kettle to heat and stir at 75-95 ℃ for 4-8 hours;

4) and centrifuging the mixed solution, washing, precipitating, drying, and calcining in a muffle furnace at 950-1150 ℃ for 2h to obtain the sphene product.

The titanium-containing sulfate is one of titanium sulfate or titanyl sulfate.

Has the advantages that: the invention provides a method for synthesizing high-purity sphene at low temperature by using xonotlite aiming at the defects of the prior art in the synthesis of sphene. Utilizes the same Ca/Si ratio of the sphene to the xonotlite and the chemical activity of the sphene to promote the chemical combination and uniform distribution between the sphene and the titanium-containing precursor in an acid environment and introduce the excessive chemical energy in the Ca-Si raw material into TiO₂And hydrolyzing the precipitated product to realize the reaction of forming the sphene at a lower calcination temperature and ensure the purity of the sphene in the product. The sphene synthesized by the method has the advantages that the required phase transition calcination temperature is reduced by about 200 ℃ compared with that of the sphene synthesized by the traditional solid phase method, the purity is very ideal, and rutile-free TiO is not generated at high temperature₂And (4) precipitating. The method has the advantages of simple synthesis process, low raw material cost, low energy consumption, little pollution and high purity of synthesized sphene, can effectively solve the problems of easy yellowing and high cost of the glaze surface of the existing titanium opacifier, and is an ideal substitute of zirconium silicate.

Drawings

FIG. 1 is an XRD diffraction pattern of calcination of the hydrolyzed precipitate product of example 1 at various temperatures.

Detailed Description

The invention is explained in more detail below with reference to the figures and examples:

example 1

1.2g of titanium sulfate solid particles are weighed and dissolved in 50mL of distilled water to prepare 0.1mol/L titanium sulfate solution, the titanium sulfate solution is magnetically stirred for 30min to be fully dissolved, and 2mol/L sodium hydroxide solution is dripped to adjust the pH value to be 2. 0.6g of xonotlite is weighed and added into the solution, the solution is stirred evenly, then sodium hydroxide solution is added into the mixed solution dropwise to adjust the pH value of the system to be 8, and the mixed solution is placed in a water bath kettle to be heated and stirred for 6 hours at 95 ℃. And cooling the sample, centrifuging and washing the sample for 10 times by using distilled water, sufficiently washing away sulfate ions (detecting barium chloride until no precipitate is generated), drying the centrifuged solid in an oven at 80 ℃, grinding the dried solid, and calcining the ground solid in a muffle furnace at 1000 ℃ for 2 hours to obtain a pure-phase sphene product, wherein the rutile-free phase is detected by XRD (detailed in figure 1).

Example 2

170mL of 0.03mol/L titanyl sulfate solution was added dropwise to adjust the pH to 2 with 2mol/L sodium hydroxide solution. 0.63g of xonotlite is weighed and added into the solution, the solution is stirred evenly, then sodium hydroxide solution is added into the mixed solution dropwise to adjust the pH value of the system to be 6, and the mixed solution is placed in a water bath kettle to be heated and stirred for 8 hours at 90 ℃. And cooling the sample, centrifuging and washing the sample for 10 times by using distilled water, sufficiently washing away sulfate ions (detecting barium chloride until no precipitate is generated), drying the centrifuged solid in an oven at 80 ℃, grinding the dried solid, and calcining the ground solid in a muffle furnace at 1050 ℃ for 2 hours to obtain a pure phase sphene product.

Example 3

10mL of 0.5mol/L titanyl sulfate solution was added dropwise to adjust the pH to 3 with 2mol/L sodium hydroxide solution. 0.52g of xonotlite is weighed and added into the solution, the solution is stirred evenly, then sodium hydroxide solution is added into the mixed solution dropwise to adjust the pH value of the system to 7, and the mixed solution is placed in a water bath kettle to be heated and stirred for 8 hours at 80 ℃. Cooling, washing with distilled water for 10 times, washing to remove sulfate ion (barium chloride detection is performed until no precipitate is generated), oven drying the centrifuged solid in oven at 80 deg.C, grinding, calcining in muffle furnace at 950 deg.CSintering for 2h to obtain sphene product without rutile phase TiO₂。

Example 4

1.2g of titanium sulfate solid particles are weighed and dissolved in 50mL of distilled water to prepare 0.1mol/L titanium sulfate solution, the titanium sulfate solution is magnetically stirred for 30min to be fully dissolved, and 2mol/L sodium hydroxide solution is dripped to adjust the pH value to be 3. 0.55g of xonotlite is weighed and added into the solution, the solution is stirred evenly, then sodium hydroxide solution is added into the mixed solution dropwise to adjust the pH value of the system to be 6.5, and the mixed solution is placed in a water bath kettle to be heated and stirred for 4 hours at 75 ℃. And cooling the sample, then centrifugally washing the sample for 10 times by using distilled water, fully washing away sulfate ions (detecting barium chloride until no precipitate is generated), drying the centrifuged solid in an oven at 80 ℃, grinding the dried solid, then placing the ground solid in a muffle furnace, and calcining the ground solid at 1150 ℃ for 2 hours to obtain a pure phase sphene product.

Claims

1. A method for preparing sphene from xonotlite is characterized by comprising the following steps: preparing 0.03-0.5 mol/L aqueous solution of titanium sulfate or titanyl sulfate, and adding sodium hydroxide solution to adjust the pH of the system to 2-3; then adding a proper amount of xonotlite powder to ensure that the molar ratio of calcium to titanium in the mixed solution is 0.86-1.05, dropwise adding a sodium hydroxide solution after uniformly stirring to adjust the pH value of the system to 6-8, placing the system in a water bath kettle, heating and stirring at 75-95 ℃ for a certain time, cooling, centrifuging, washing and drying; and calcining the obtained powder in a muffle furnace at 950-1150 ℃ for a certain time to obtain a high-purity sphene product.