TWI558816B - Calcium fluoride powder or sludge granulation method - Google Patents

Description

Granulation method of calcium fluoride powder or sludge

The present invention relates to a granulation method, and more particularly to a granulation method of a calcium fluoride powder or sludge.

The wafer factory often uses a large amount of hydrofluoric acid in the process. After use, the hydrofluoric acid waste liquid will first adjust the appropriate pH value with sodium hydroxide, and then react with calcium chloride or calcium hydroxide. The calcium fluoride precipitate is finally dehydrated by pressure filtration or other methods to obtain calcium fluoride sludge (Calcium Fluoride Sludge), and the water content is often between 60% and 80%. In order to further reduce the water content, a drying step may be further performed to obtain a calcium fluoride powder.

Since calcium fluoride is the main component of fluorspar, fluorite is widely used in industrial applications such as glass, ceramics, cement, and steel. For example, when the steel is used to improve the fluidity of the melt and remove harmful impurities, the use of calcium fluoride powder or sludge as a fluorite for steelmaking can be recycled and commercialized. However, calcium fluoride powder or sludge is made into fluorite for steelmaking, which must be specially treated to ensure that the composition meets the steelmaking requirements. For example, the weight percentage of calcium fluoride is not less than 75%, and the water content is not more than 2%. And cerium oxide is not more than 18%. In addition, the structural strength of fluorite for steelmaking also has certain requirements, and it must be more than 88% by weight of 6.3 cm after passing the drum test. Referring to Figure 1, a calcium fluoride sludge resource recovery treatment method disclosed in Taiwan No. 496796 Patent Approved Announcement No., mainly uses calcium fluoride sludge and an oxygen-friendly material, a flux, a reducing agent, a heat generating agent, and a hardener. Press mixing, then cold granulation into fluorite for steelmaking. However, such a treatment method adds a relatively complicated chemical material and increases the processing cost.

As can be seen from the above description, the simple use of calcium fluoride powder or sludge as fluorite for steelmaking is a problem to be solved by those skilled in the art.

Accordingly, it is an object of the present invention to provide a method of granulating a calcium fluoride powder or sludge.

Thus, the granulation method of the calcium fluoride powder or sludge of the present invention comprises a mixing step and a granulation step.

The mixing step thoroughly mixes the calcium fluoride powder or sludge, an asphalt (Asphalt), and water into a premix.

The granulation step granulates the premix to obtain a plurality of calcium fluoride blocks.

The effect of the present invention is that the calcium fluoride powder or the sludge can be granulated by using only the asphalt as a binder, thereby making fluorite suitable for steelmaking, thereby reducing the processing cost.

As shown in FIG. 2, an embodiment of the granulation method of the calcium fluoride powder or sludge of the present invention comprises a pulverization step 11, a mixing step 12, a granulation step 13, and a dehumidification step 14 in sequence. .

The pulverizing step 11 is obtained by taking calcium fluoride sludge produced by a semiconductor factory, and dehydrating and high-temperature calcining into an agglomerate having a particle size larger than 0.5 mm and mechanically pulverized by a pulverizer. Calcium fluoride powder, the powder particle size is less than 0.5 mm.

The mixing step 12 thoroughly mixes the calcium fluoride powder or sludge, an emulsified asphalt, and water at room temperature in a five-stage bowl mixer for 30 minutes to form a premix.

It should be noted that the purpose of the pulverization step 11 is to increase the total surface area of the calcium fluoride powder, increase the contact area between the powder particles and the emulsified asphalt, and further improve the structural strength of the premix.

Asphalt is a kind of bonding material with excellent performance, which has the advantages of quick construction, simple process, resource saving and low pollution. However, the general asphalt must be melted under high temperature conditions, and it is not convenient to use. Therefore, in this case, Emulsified Asphalt (EA) is used as a binder, because the emulsified asphalt is liquid at normal temperature, so Not only can the asphalt be excellent in adhesion at the same time, but it can also be mixed at room temperature for easier operation. In detail, emulsified asphalt consists of three main substances: asphalt, water and emulsifiers. Among them, the emulsifier is used to reduce the interfacial tension between asphalt and water, the content is about 0.3-5%, and different emulsifiers are selected according to the use of different emulsified asphalt. In this embodiment, the emulsified asphalt is purchased from Yusheng Technology Co., Ltd. Preferably, the emulsified asphalt comprises from 1% to 20% by weight of the premix, and the water in the premix comprises from 10% to 80% by weight of the premix. In order to further facilitate the granulation of the premix, and the calcium fluoride content of the calcium fluoride particles prepared from the premix can meet the steelmaking standard, the water in the mixing step 12 accounts for the premix. The weight percentage ranges from 20% to 60%, and the emulsified asphalt accounts for 3% to 13% by weight of the premix.

In addition, it should be noted that the pulverizing step 11 described above may also be performed according to the process, in particular, the calcium fluoride powder has a particle diameter of less than 0.5 mm, or the mixing step 12 may be directly performed when the calcium fluoride sludge is used. .

It is worth mentioning that the present invention can also directly use asphalt as a binder without mixing with an emulsifier to form an emulsified asphalt. When the asphalt is directly used as a binder, the mixing step 12 is at a temperature of 130 ° C. Calcium fluoride powder or sludge, water, and asphalt can be mixed and mixed.

Next, the granulation step 13 is carried out, and the premix is subjected to granulation treatment by a stirring mixing granulation method to obtain a plurality of calcium fluoride bulks. Preferably, in order to be applied to the steelmaking industry, the calcium fluoride block size should be between 10 mm and 70 mm.

Finally, the dehumidifying step 14 is carried out, and the calcium fluoride blocks are dried, dried at a temperature of not more than 100 ° C, and the water content of the calcium fluoride blocks is adjusted to 3% or less. The calcium fluoride content of the dried calcium fluoride blocks after drying is confirmed by thermogravimetry and X-ray diffraction analysis to be 84.2%, which can meet the steelmaking demand standard (the weight percentage of calcium fluoride is not less than 75%). ). It should be noted that the drying temperature must be controlled to not more than 100 ° C to avoid boiling of water and destroy the structural strength of the block.

In order to further test the structural strength of the article of this example, the calcium fluoride block obtained in the granulation step 13 was formed into a columnar sample having a diameter of 5 cm and a height of 1.9 cm, and allowed to stand at room temperature. After the hour, the mold was released, and then dried at 95 ° C for 5 hr, and then cured at room temperature. When the test age of seven days was reached, the barrel strength test was carried out according to the Japanese Industrial Standard JIS M 8712-1971 specification. Briefly, the drum strength test measures the weight ratio of the granulated test piece to the 6.3 mm screen after 13 turns of the drum. Referring to Figure 3, when the emulsified asphalt reaches 7%, the weight ratio of the un-passed 6.3 mm screen can reach 88.2%, indicating that the strength of the calcium fluoride block produced by the present invention meets the demand standard of the refinable steel (failed 6.3) The weight ratio of the mm screen must be over 88%).

In summary, the present invention can make calcium fluoride powder or sludge into fluorite for steel making by using asphalt or emulsified asphalt as an adhesive, thereby reducing the processing cost. Therefore, the object of the present invention can be achieved.

The above is only the preferred embodiment of the present invention, and the scope of the present invention is not limited thereto, and the simple equivalent changes and modifications made by the scope of the patent application and the patent specification of the present invention are It is still within the scope of the invention patent.

11‧‧‧Smashing steps
13‧‧‧granulation step
12‧‧‧mixing step
14‧‧‧Dehumidification step

Other features and effects of the present invention will be apparent from the following description of the drawings, wherein: Figure 1 is a flow diagram illustrating a calcium fluoride sludge disclosed by Taiwan Patent No. 496796 Approved Publication No. FIG. 2 is a flow chart showing a method of granulating a calcium fluoride powder or sludge according to the present invention; and FIG. 3 is a data chart of a rotary drum test, illustrating the system of the embodiment. The structural strength of the resulting product.

11‧‧‧Smashing steps

12‧‧‧mixing step

13‧‧‧granulation step

14‧‧‧Dehumidification step

Claims (6)

The invention relates to a granulation method of calcium fluoride powder or sludge, comprising: a mixing step: mixing asphalt with an emulsifier and water to form an emulsified asphalt, and then fully mixing with calcium fluoride powder or sludge and water. Forming a premix, wherein the emulsified asphalt comprises from 1% to 20% by weight of the premix, and water comprises from 10% to 80% by weight of the premix; and a granulation step: The premix was subjected to granulation treatment to obtain a plurality of calcium fluoride blocks. The method for granulating calcium fluoride powder or sludge according to claim 1, wherein the emulsified asphalt in the mixing step accounts for 3% to 13% by weight of the premix, and the water is The weight percentage of the premix is between 20% and 60%. The method for granulating calcium fluoride powder or sludge according to claim 1, further comprising a pulverizing step performed before the mixing step, the pulverizing step is pulverizing the calcium fluoride agglomerate into A powder of calcium fluoride having a powder particle size of less than 0.5 mm. The method for granulating calcium fluoride powder or sludge according to claim 1, further comprising a dehumidifying step performed after the granulating step, wherein the dehumidifying step is to dry the calcium fluoride blocks. deal with. The method for granulating calcium fluoride powder or sludge according to claim 4, wherein the calcium fluoride content of the calcium fluoride bulk after drying in the dehumidifying step is not less than 75%. The method for granulating calcium fluoride powder or sludge according to claim 4, wherein the dehumidifying step is drying at a temperature not higher than 100 ° C, and adjusting the water content of the calcium fluoride block to Less than 3%.