CN100582035C - Method for preparing cristobalite by calcining quartz - Google Patents

Abstract

The invention disclose a preparing method of cristobalite through calcining quartz, which comprises the following steps: 1) mixing quartz power and phase-change activator; getting batches; compositing Y2O3,Na2CO and BaF2 as phase-change activator; making the adding quantity of Y2O3, Na2CO3 and BaF2 separately at 1 per mill -5 per mill , 5 per mill -10 per mill and 1 per mill -5 per mill against the weight of quartz power; 2) heating the batches up to 1300 deg.c with speed of 2-10 deg.c per minuet; keeping temperature at 1300 deg.c at 6 h; getting product with quartz phase bigger-than 94%.

Description

A method for preparing cristobalite by calcining quartz

technical field

The invention relates to a method for preparing cristobalite by calcining quartz.

Background technique

Cristobalite is a mineral species in the quartz group of minerals, which is divided into high-temperature cristobalite (α-cristobalite) and low-temperature cristobalite (β-cristobalite). The phase transition temperature between them is 200-270 ° C, accompanied by a large volume change. Natural cristobalite is generally produced in the bubbles formed by volcanic rocks, without natural minerals. Quartz group minerals have a phase transition process at different temperatures and pressures. When the temperature reaches 1470 ° C, quartz will transform into α-cristobalite. This property is usually used for industrial production of cristobalite. Due to its unique properties, cristobalite powder has been widely used in precision casting, high-grade electric porcelain, dental materials, electronic chips, polishing materials, special ceramic materials, special refractory materials, high-grade papermaking, high-grade coatings, shielding materials, daily chemicals, Adhesives, plastics, silicone rubber and other industries, and their import prices are very high. As the consumption increases year by year, the localization of cristobalite powder has become increasingly urgent.

There are two ways to produce cristobalite: one is to calcinate the quartz powder at 1500°C (the transformation temperature from quartz to cristobalite is 1470°C, considering the temperature imbalance in the furnace to ensure thorough calcination), heat preservation for 3 -6 hours. Another method is to directly calcine block quartz to prepare cristobalite (such as Chinese Patent No.: ZL00107107.6). The process flow is: block material → cleaning → impurity removal → kiln loading → calcination → heat preservation → kiln exit → impurity removal → Ball milling → bagging and storage.

According to domestic literature reports, there are several ways to reduce the calcination temperature of cristobalite: one is to add metal oxides, see (Wang Jinshu, etc. Research on the conversion rate of quartz to α-cristobalite [J]. Chinese Ceramics, 1992 (6): 1-5), it is reported in the paper that alumina is an ideal phase change catalyst. When the addition amount is 4%, the conversion rate is up to 42.2% at 1320°C; the second is the lime-iron catalyst widely used in current production. (CaO+FeO) or iron-lime (FeO+CaO) mineralizer, the former is more widely used, the addition amount is: CaO about 2.5%, FeO(Fe ₂ O ₃ ) 0.5-1.0%, usually the addition amount is 3-4%; the third is to use fluorine-containing compounds as mineralizers, which can greatly accelerate the conversion of quartz, and the conversion rate can reach 85% at 1400 °C. The main defect of the above method is that the amount of additive added is too large, which affects the purity of cristobalite, and the conversion rate is low.

Contents of the invention

The object of the present invention is to provide a method for preparing cristobalite by calcining quartz, which has low energy consumption, low production cost and high conversion rate.

In order to achieve the above object, the technical solution of the present invention is: a method for preparing cristobalite by calcining quartz, characterized in that it comprises the following steps:

1) Mix the quartz powder and the phase-change catalyst evenly to obtain a batch; the phase-change catalyst is a composite catalyst composed of Y ₂ O ₃ , Na ₂ CO ₃ and BaF ₂ , and the amount of Y ₂ O ₃ added 1‰-5‰ of the weight of the quartz powder, the amount of Na ₂ CO ₃ added is 5‰-10‰ of the weight of the quartz powder, and the amount of BaF ₂ added is 1‰-5‰ of the weight of the quartz powder;

2) Raise the temperature of the batch material to 1300°C at a rate of 2°C-10°C per minute, and keep it at 1300°C for 6 hours to obtain a product with a cristobalite phase greater than 94%.

The particle size of the quartz powder is less than 100 mesh (0.149mm), and the content of SiO ₂ is greater than 99.8%.

The present invention mixes quartz powder with a composite catalyst composed of Y ₂ O ₃ , Na ₂ CO ₃ and BaF ₂ , which can reduce the conversion temperature of quartz to cristobalite from 1470°C to 1300°C, and the conversion rate is greater than 94%. . Compared with the prior art, the present invention has the outstanding advantages that it can reduce energy consumption and production cost, and has high conversion rate (greater than 94%).

Features of the present invention are mainly reflected in:

1. The amount of phase change catalyst is less (less than 2%), and the amount of mineralizer added in conventional methods is 3-4%.

2. The calcination temperature is low (1300°C), and the calcination temperature of the conventional method is above 1500°C.

3. The conversion rate of cristobalite is high (greater than 94%).

The application field of the invention is the field of refractory materials, and particularly relates to a cristobalite material. The invention can improve the existing production process, reduce energy consumption, save energy, reduce pollution, greatly reduce production cost, and make the product more competitive in the market.

Description of drawings

Figure 1 is the XRD pattern obtained in Comparative Example 1 [quartz powder without adding a phase change catalyst, calcined at 1300° C. for 6 hours].

Fig. 2 is the XRD pattern obtained in comparative example 2 [quartz powder is added with 5‰ yttrium oxide, 10‰ sodium carbonate, 5‰ barium fluoride, calcined at 1300° C. for 6 hours].

Fig. 3 is the XRD pattern obtained in Example 1 of the present invention [quartz powder is added with 2‰ yttrium oxide, 8‰ sodium carbonate, 5‰ barium fluoride, and calcined at 1300°C for 6 hours].

Fig. 4 is the XRD pattern obtained in Example 2 of the present invention [quartz powder is added with 5‰ yttrium oxide, 9‰ sodium carbonate, 3‰ barium fluoride, and calcined at 1300°C for 6 hours].

Fig. 5 is the XRD pattern obtained in Example 3 of the present invention [quartz powder is added with 4‰ yttrium oxide, 8‰ sodium carbonate, 5‰ barium fluoride, and calcined at 1300°C for 6 hours].

Fig. 6 is the XRD pattern obtained in Example 4 of the present invention [quartz powder is added with 5‰ yttrium oxide, 8‰ sodium carbonate, 5‰ barium fluoride, and calcined at 1300°C for 6 hours].

Fig. 7 is the XRD pattern obtained in Example 5 of the present invention [quartz powder is added with 3‰ yttrium oxide, 8‰ sodium carbonate, 4‰ barium fluoride, and calcined at 1300°C for 6 hours].

Fig. 8 is the XRD pattern obtained in Example 6 of the present invention [quartz powder is added with 4‰ yttrium oxide, 8‰ sodium carbonate, 4‰ barium fluoride, and calcined at 1300°C for 6 hours].

Detailed ways

In order to better understand the present invention, the content of the present invention is further illustrated below in conjunction with the examples, but the content of the present invention is not limited to the following examples.

Embodiment one:

Put 5.00g of quartz powder less than 0.149mm into a corundum crucible, add yttrium oxide with a weight of 2‰ of the quartz powder, add sodium carbonate with a weight of 8‰ of the quartz powder, and add barium fluoride with a weight of 5‰ of the quartz powder, and mix well , placed in a silicon-molybdenum rod box-type resistance furnace, heated to 1300°C at a rate of 4°C per minute, and kept at 1300°C for 6 hours to obtain a cristobalite product, which was analyzed by X powder crystal diffraction to obtain an XRD pattern 3 . It can be seen from Figure 3 that the conversion rate of cristobalite is 95.23%.

Embodiment two:

Put 5.00g of quartz powder less than 0.149mm into a corundum crucible, add yttrium oxide with a weight of 5‰ of the quartz powder, add sodium carbonate with a weight of 9‰ of the quartz powder, and add barium fluoride with a weight of 3‰ of the quartz powder, and mix well , placed in a silicon-molybdenum rod box-type resistance furnace, heated up to 1300°C at a rate of 4°C per minute, and kept at 1300°C for 6 hours to obtain a cristobalite product, which was analyzed by X powder crystal diffraction to obtain an XRD pattern 4 . It can be seen from Figure 4 that the conversion rate of cristobalite is 94.34%.

Embodiment three:

Put 5.00g of quartz powder less than 0.149mm into a corundum crucible, add yttrium oxide with a weight of 4‰ of the quartz powder, add sodium carbonate with a weight of 8‰ of the quartz powder, and add barium fluoride with a weight of 5‰ of the quartz powder, and mix well , placed in a silicon-molybdenum rod box-type resistance furnace, heated up to 1300°C at a rate of 4°C per minute, and kept at 1300°C for 6 hours to obtain a cristobalite product, which was analyzed by X powder crystal diffraction to obtain an XRD pattern 5 . It can be seen from Figure 5 that the conversion rate of cristobalite is 95.23%.

Embodiment four:

Put 5.00g of quartz powder less than 0.149mm into a corundum crucible, add yttrium oxide with a weight of 5‰ of the quartz powder, sodium carbonate with a weight of 8‰ of the quartz powder, and barium fluoride with a weight of 5‰ of the quartz powder, mix well, and put Put it into a silicon-molybdenum rod box-type resistance furnace, raise the temperature to 1300°C at a rate of 4°C per minute, and keep it at 1300°C for 6 hours to obtain a cristobalite product. The product is subjected to X powder crystal diffraction analysis to obtain an XRD pattern 6. It can be seen from Figure 6 that the conversion rate of cristobalite is 94.34%.

Embodiment five:

Put 5.00g of quartz powder less than 0.149mm into a corundum crucible, add yttrium oxide with a weight of 3‰ of the quartz powder, add sodium carbonate with a weight of 8‰ of the quartz powder, and add barium fluoride with a weight of 4‰ of the quartz powder, and mix well , placed in a silicon-molybdenum rod box-type resistance furnace, heated to 1300°C at a rate of 4°C per minute, and kept at 1300°C for 6 hours to obtain a cristobalite product, which was analyzed by X powder crystal diffraction to obtain an XRD pattern 7 . It can be seen from Figure 7 that the conversion rate of cristobalite is 94.34%.

Embodiment six:

Put 5.00g of quartz powder less than 0.149mm into a corundum crucible, add yttrium oxide with a weight of 4‰ of the quartz powder, add sodium carbonate with a weight of 8‰ of the quartz powder, and add barium fluoride with a weight of 4‰ of the quartz powder, and mix well , placed in a silicon-molybdenum rod box-type resistance furnace, heated to 1300°C at a rate of 4°C per minute, and kept at 1300°C for 6 hours to obtain a cristobalite product, which was analyzed by X powder crystal diffraction to obtain an XRD pattern 8 . It can be seen from Figure 8 that the conversion rate of cristobalite is 96.15%.

Embodiment seven:

Put 5.00g of quartz powder less than 0.149mm into a corundum crucible, add yttrium oxide with a weight of 1‰ of the quartz powder, add sodium carbonate with a weight of 5‰ of the quartz powder, and add barium fluoride with a weight of 1‰ of the quartz powder, and mix well , placed in a silicon-molybdenum rod box-type resistance furnace, heated up to 1300°C at a rate of 10°C per minute, and kept at 1300°C for 6 hours to obtain a cristobalite product.

Embodiment eight:

Put 5.00g of quartz powder less than 0.149mm into a corundum crucible, add yttrium oxide with a weight of 5‰ of the quartz powder, add sodium carbonate with a weight of 10‰ of the quartz powder, and add barium fluoride with a weight of 5‰ of the quartz powder, and mix well , placed in a silicon-molybdenum rod box-type resistance furnace, heated up to 1300°C at a rate of 2°C per minute, and kept at 1300°C for 6 hours to obtain a cristobalite product.

Comparative Example 1:

Put 5.00g of quartz powder less than 0.149mm into a corundum crucible, put it into a silicon-molybdenum rod box-type resistance furnace without adding a phase change catalyst, and raise the temperature to 1300°C at a rate of 4°C per minute. ℃ for 6 hours to obtain a cristobalite product, which was subjected to X powder crystal diffraction analysis to obtain an XRD pattern 1. It can be seen from Figure 1 that the conversion rate of cristobalite is less than 10%.

Comparative example 2:

Put 5.00g of quartz powder less than 0.149mm into a corundum crucible, add yttrium oxide with a weight of 5‰ of the quartz powder, add sodium carbonate with a weight of 10‰ of the quartz powder, and add barium fluoride with a weight of 5‰ of the quartz powder, and mix well , placed in a silicon-molybdenum rod box-type resistance furnace, heated to 1300°C at a rate of 4°C per minute, and kept at 1300°C for 6 hours to obtain a cristobalite product, which was analyzed by X powder crystal diffraction to obtain an XRD pattern 2 . It can be seen from Figure 2 that the conversion rate of cristobalite is greater than 94%.

Claims (2)

1. the method for a preparing cristobalite by calcining quartz is characterized in that it comprises the steps:

1), quartz powder materials and phase-change catalyst are mixed, admixtion; Described phase-change catalyst is Y ₂O ₃, Na ₂CO ₃And BaF ₂The composite catalyst of being formed, Y ₂O ₃Add-on be 1 ‰ of quartz powder materials weight-5 ‰, Na ₂CO ₃Add-on be 5 ‰ of quartz powder materials weight-10 ‰, BaF ₂Add-on be 1 ‰ of quartz powder materials weight-5 ‰;

2), admixtion is warming up to 1300 ℃ with the speed of 2 ℃-10 ℃ of per minutes, 1300 ℃ of insulations 6 hours, cristobalite greater than 94% product.

2. the method for a kind of preparing cristobalite by calcining quartz according to claim 1, it is characterized in that: the particle diameter of described quartz powder materials is less than 100 orders, and SiO ₂Content greater than 99.8%.

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